query: Less than 10% of patients exposed to radiation have activated markers of mesenchymal stem cells.

title: KLF4-dependent phenotypic modulation of smooth muscle cells has a key role in atherosclerotic plaque pathogenesis

text: Previous studies investigating the role of smooth muscle cells (SMCs) and macrophages in the pathogenesis of atherosclerosis have provided controversial results owing to the use of unreliable methods for clearly identifying each of these cell types. Here, using Myh11-CreERT2 ROSA floxed STOP eYFP Apoe−/− mice to perform SMC lineage tracing, we find that traditional methods for detecting SMCs based on immunostaining for SMC markers fail to detect >80% of SMC-derived cells within advanced atherosclerotic lesions. These unidentified SMC-derived cells exhibit phenotypes of other cell lineages, including macrophages and mesenchymal stem cells (MSCs). SMC-specific conditional knockout of Krüppel-like factor 4 (Klf4) resulted in reduced numbers of SMC-derived MSC- and macrophage-like cells, a marked reduction in lesion size, and increases in multiple indices of plaque stability, including an increase in fibrous cap thickness as compared to wild-type controls. On the basis of in vivo KLF4 chromatin immunoprecipitation–sequencing (ChIP-seq) analyses and studies of cholesterol-treated cultured SMCs, we identified >800 KLF4 target genes, including many that regulate pro-inflammatory responses of SMCs. Our findings indicate that the contribution of SMCs to atherosclerotic plaques has been greatly underestimated, and that KLF4-dependent transitions in SMC phenotype are critical in lesion pathogenesis.

title: FGF-2 enhances intestinal stem cell survival and its expression is induced after radiation injury.

text: Fibroblast growth factors (FGFs) have mitogenic activity toward a wide variety of cells of mesenchymal, neuronal, and epithelial origin and regulate events in normal embryonic development, angiogenesis, wound repair, and neoplasia. FGF-2 is expressed in many normal adult tissues and can regulate migration and replication of intestinal epithelial cells in culture. However, little is known about the effects of FGF-2 on intestinal epithelial stem cells during either normal epithelial renewal or regeneration of a functional epithelium after injury. In this study, we investigated the expression of FGF-2 in the mouse small intestine after irradiation and determined the effect of exogenous FGF-2 on crypt stem cell survival after radiation injury. Expression of FGF-2 mRNA and protein began to increase at 12 h after gamma-irradiation, and peak levels were observed from 48 to 120 h after irradiation. At all times after irradiation, the higher molecular mass isoform ( approximately 24 kDa) of FGF-2 was the predominant form expressed in the small intestine. Immunohistochemical analysis of FGF-2 expression after radiation injury demonstrated that FGF-2 was predominantly found in the mesenchyme surrounding regenerating crypts. Exogenous recombinant human FGF-2 (rhFGF-2) markedly enhanced crypt stem cell survival when given before irradiation. We conclude that expression of FGF-2 is induced by radiation injury and that rhFGF-2 can enhance crypt stem cell survival after subsequent injury.

title: Comparison of allogeneic vs autologous bone marrow–derived mesenchymal stem cells delivered by transendocardial injection in patients with ischemic cardiomyopathy: the POSEIDON randomized trial.

text:
CONTEXT Mesenchymal stem cells (MSCs) are under evaluation as a therapy for ischemic cardiomyopathy (ICM). Both autologous and allogeneic MSC therapies are possible; however, their safety and efficacy have not been compared.
 OBJECTIVE To test whether allogeneic MSCs are as safe and effective as autologous MSCs in patients with left ventricular (LV) dysfunction due to ICM.
 DESIGN, SETTING, AND PATIENTS A phase 1/2 randomized comparison (POSEIDON study) in a US tertiary-care referral hospital of allogeneic and autologous MSCs in 30 patients with LV dysfunction due to ICM between April 2, 2010, and September 14, 2011, with 13-month follow-up.
 INTERVENTION Twenty million, 100 million, or 200 million cells (5 patients in each cell type per dose level) were delivered by transendocardial stem cell injection into 10 LV sites.
 MAIN OUTCOME MEASURES Thirty-day postcatheterization incidence of predefined treatment-emergent serious adverse events (SAEs). Efficacy assessments included 6-minute walk test, exercise peak VO2, Minnesota Living with Heart Failure Questionnaire (MLHFQ), New York Heart Association class, LV volumes, ejection fraction (EF), early enhancement defect (EED; infarct size), and sphericity index.
 RESULTS Within 30 days, 1 patient in each group (treatment-emergent SAE rate, 6.7%) was hospitalized for heart failure, less than the prespecified stopping event rate of 25%. The 1-year incidence of SAEs was 33.3% (n = 5) in the allogeneic group and 53.3% (n = 8) in the autologous group (P = .46). At 1 year, there were no ventricular arrhythmia SAEs observed among allogeneic recipients compared with 4 patients (26.7%) in the autologous group (P = .10). Relative to baseline, autologous but not allogeneic MSC therapy was associated with an improvement in the 6-minute walk test and the MLHFQ score, but neither improved exercise VO2 max. Allogeneic and autologous MSCs reduced mean EED by −33.21% (95% CI, −43.61% to −22.81%; P < .001) and sphericity index but did not increase EF. Allogeneic MSCs reduced LV end-diastolic volumes. Low-dose concentration MSCs (20 million cells) produced greatest reductions in LV volumes and increased EF. Allogeneic MSCs did not stimulate significant donor-specific alloimmune reactions.
 CONCLUSIONS In this early-stage study of patients with ICM, transendocardial injection of allogeneic and autologous MSCs without a placebo control were both associated with low rates of treatment-emergent SAEs, including immunologic reactions. In aggregate, MSC injection favorably affected patient functional capacity, quality of life, and ventricular remodeling.
 TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT01087996.

title: The Epithelial-Mesenchymal Transition Generates Cells with Properties of Stem Cells

text: The epithelial-mesenchymal transition (EMT) is a key developmental program that is often activated during cancer invasion and metastasis. We here report that the induction of an EMT in immortalized human mammary epithelial cells (HMLEs) results in the acquisition of mesenchymal traits and in the expression of stem-cell markers. Furthermore, we show that those cells have an increased ability to form mammospheres, a property associated with mammary epithelial stem cells. Independent of this, stem cell-like cells isolated from HMLE cultures form mammospheres and express markers similar to those of HMLEs that have undergone an EMT. Moreover, stem-like cells isolated either from mouse or human mammary glands or mammary carcinomas express EMT markers. Finally, transformed human mammary epithelial cells that have undergone an EMT form mammospheres, soft agar colonies, and tumors more efficiently. These findings illustrate a direct link between the EMT and the gain of epithelial stem cell properties.

title: Embryonic-like stem cell derived from adult bone marrow: immature morphology, cell surface markers, ultramicrostructure and differentiation into multinucleated fibers in vitro.

text: Embryonic-like stem cell (ELSC), expressing part of surface markers of human embryonic stem cells, may be a better candidate for cell therapy of degenerative muscular disease than mesenchymal stem cell (MSC). We isolated ELSC and MSC from bone marrow, respectively, and compared their differences in the characteristics and the capacity of myogenic differentiation. Results showed that ELSC could be isolated successfully from 3 adult bone marrow samples by using serum-free medium with 10ng/ml basic fibroblast growth factor (bFGF). At the same cell density, MSC could also be isolated from the same samples by using DMEM/F12 medium containing 10% new cattle serum. However, ELSC appeared as small, morphologically slenderer, upregulated expression of SSEA-4 and ultramicroscopically more immature than MSC derived from the same samples. Immunofluorescent staining and RT-PCR analysis showed ELSC weakly expressed Oct-4, Nanog-3 and Sox-2. Moreover, ELSC and MSC could be induced into long, multinucleated fibers expressing myogenin and myosin heavy chain (MHC) in myogenic differentiation medium, but by day 10, proportion of multinucleated fibers positive for MHC was respectively 25.0%+/-6.9% and 13.8%+/-7.6% in ELSC and MSC culture. These data suggest that bone marrow derived ELSC represent an ideal candidate for cell therapy of degenerative muscular disease.

title: Haematopoietic stem cells do not asymmetrically segregate chromosomes or retain BrdU

text: Stem cells are proposed to segregate chromosomes asymmetrically during self-renewing divisions so that older (‘immortal’) DNA strands are retained in daughter stem cells whereas newly synthesized strands segregate to differentiating cells. Stem cells are also proposed to retain DNA labels, such as 5-bromo-2-deoxyuridine (BrdU), either because they segregate chromosomes asymmetrically or because they divide slowly. However, the purity of stem cells among BrdU-label-retaining cells has not been documented in any tissue, and the ‘immortal strand hypothesis’ has not been tested in a system with definitive stem cell markers. Here we tested these hypotheses in haematopoietic stem cells (HSCs), which can be highly purified using well characterized markers. We administered BrdU to newborn mice, mice treated with cyclophosphamide and granulocyte colony-stimulating factor, and normal adult mice for 4 to 10 days, followed by 70 days without BrdU. In each case, less than 6% of HSCs retained BrdU and less than 0.5% of all BrdU-retaining haematopoietic cells were HSCs, revealing that BrdU has poor specificity and poor sensitivity as an HSC marker. Sequential administration of 5-chloro-2-deoxyuridine and 5-iodo-2-deoxyuridine indicated that all HSCs segregate their chromosomes randomly. Division of individual HSCs in culture revealed no asymmetric segregation of the label. Thus, HSCs cannot be identified on the basis of BrdU-label retention and do not retain older DNA strands during division, indicating that these are not general properties of stem cells.

title: Epithelial to Mesenchymal Transition by TGFβ-1 Induction Increases Stemness Characteristics in Primary Non Small Cell Lung Cancer Cell Line

text:
BACKGROUND Cancer Stem Cells (CSCs) hypothesis asserts that only a small subset of cells within a tumour is capable of both tumour initiation and sustainment. The Epithelial-Mesenchymal Transition (EMT) is an embryonic developmental program that is often activated during cancer invasion and metastasis. The aim of this study is to shed light on the relationship between EMT and CSCs by using LC31 lung cancer primary cell line.    MATERIALS AND METHODS A549 and LC31 cell lines were treated with 2 ng/ml TGFβ-1 for 30 days, and 80 days, respectively. To evaluate EMT, morphological changes were assessed by light microscopy, immunofluorescence and cytometry for following markers: cytokeratins, e-cadherin, CD326 (epithelial markers) and CD90, and vimentin (mesenchymal markers). Moreover, RT-PCR for Slug, Twist and β-catenin genes were performed. On TGFβ-1 treated and untreated LC31 cell lines, we performed stemness tests such as pneumospheres growth and stem markers expression such as Oct4, Nanog, Sox2, c-kit and CD133. Western Blot for CD133 and tumorigenicity assays using NOD/SCID mice were performed.
 RESULTS TGFβ-1 treated LC31 cell line lost its epithelial morphology assuming a fibroblast-like appearance. The same results were obtained for the A549 cell line (as control). Immunofluorescence and cytometry showed up-regulation of vimentin and CD90 and down-regulation of cytocheratin, e-cadherin and CD326 in TGFβ-1 treated LC31 and A549 cell lines. Slug, Twist and β-catenin m-RNA transcripts were up-regulated in TGFβ-1 treated LC31 cell line confirming EMT. This cell line showed also over-expression of Oct4, Nanog, Sox2 and CD133, all genes of stemness. In addition, in TGFβ-1 treated LC31 cell line, an increased pneumosphere-forming capacity and tumours-forming ability in NOD/SCID mice were detectable.
 CONCLUSIONS The induction of EMT by TGFβ-1 exposure, in primary lung cancer cell line results in the acquisition of mesenchymal profile and in the expression of stem cell markers.

title: The antidiabetic effect of mesenchymal stem cells is unrelated to their transdifferentiation potential but to their capability to restore Th1/Th2 balance and to modify the pancreatic microenvironment.

text: Type 1 diabetes mellitus (T1DM) is a chronic metabolic disease that results from cell-mediated autoimmune destruction of insulin-producing cells. In T1DM animal models, it has been shown that the systemic administration of multipotent mesenchymal stromal cells, also referred as to mesenchymal stem cells (MSCs), results in the regeneration of pancreatic islets. Mechanisms underlying this effect are still poorly understood. Our aims were to assess whether donor MSCs (a) differentiate into pancreatic β-cells and (b) modify systemic and pancreatic pathophysiologic markers of T1DM. After the intravenous administration of 5 × 10(5) syngeneic MSCs, we observed that mice with T1DM reverted their hyperglycemia and presented no donor-derived insulin-producing cells. In contrast, 7 and 65 days post-transplantation, MSCs were engrafted into secondary lymphoid organs. This correlated with a systemic and local reduction in the abundance of autoaggressive T cells together with an increase in regulatory T cells. Additionally, in the pancreas of mice with T1DM treated with MSCs, we observed a cytokine profile shift from proinflammatory to antinflammatory. MSC transplantation did not reduce pancreatic cell apoptosis but recovered local expression and increased the circulating levels of epidermal growth factor, a pancreatic trophic factor. Therefore, the antidiabetic effect of MSCs intravenously administered is unrelated to their transdifferentiation potential but to their capability to restore the balance between Th1 and Th2 immunological responses along with the modification of the pancreatic microenvironment. Our data should be taken into account when designing clinical trials aimed to evaluate MSC transplantation in patients with T1DM since the presence of endogenous precursors seems to be critical in order to restore glycemic control.

title: Stereotactic radiosurgery plus whole-brain radiation therapy vs stereotactic radiosurgery alone for treatment of brain metastases: a randomized controlled trial.

text:
CONTEXT In patients with brain metastases, it is unclear whether adding up-front whole-brain radiation therapy (WBRT) to stereotactic radiosurgery (SRS) has beneficial effects on mortality or neurologic function compared with SRS alone.
 OBJECTIVE To determine if WBRT combined with SRS results in improvements in survival, brain tumor control, functional preservation rate, and frequency of neurologic death.
 DESIGN, SETTING, AND PATIENTS Randomized controlled trial of 132 patients with 1 to 4 brain metastases, each less than 3 cm in diameter, enrolled at 11 hospitals in Japan between October 1999 and December 2003.
 INTERVENTIONS Patients were randomly assigned to receive WBRT plus SRS (65 patients) or SRS alone (67 patients).
 MAIN OUTCOME MEASURES The primary end point was overall survival; secondary end points were brain tumor recurrence, salvage brain treatment, functional preservation, toxic effects of radiation, and cause of death.
 RESULTS The median survival time and the 1-year actuarial survival rate were 7.5 months and 38.5% (95% confidence interval, 26.7%-50.3%) in the WBRT + SRS group and 8.0 months and 28.4% (95% confidence interval, 17.6%-39.2%) for SRS alone (P = .42). The 12-month brain tumor recurrence rate was 46.8% in the WBRT + SRS group and 76.4% for SRS alone group (P<.001). Salvage brain treatment was less frequently required in the WBRT + SRS group (n = 10) than with SRS alone (n = 29) (P<.001). Death was attributed to neurologic causes in 22.8% of patients in the WBRT + SRS group and in 19.3% of those treated with SRS alone (P = .64). There were no significant differences in systemic and neurologic functional preservation and toxic effects of radiation.
 CONCLUSIONS Compared with SRS alone, the use of WBRT plus SRS did not improve survival for patients with 1 to 4 brain metastases, but intracranial relapse occurred considerably more frequently in those who did not receive WBRT. Consequently, salvage treatment is frequently required when up-front WBRT is not used.
 TRIAL REGISTRATION umin.ac.jp/ctr Identifier: C000000412.

title: Geometric cues for directing the differentiation of mesenchymal stem cells.

text: Significant efforts have been directed to understanding the factors that influence the lineage commitment of stem cells. This paper demonstrates that cell shape, independent of soluble factors, has a strong influence on the differentiation of human mesenchymal stem cells (MSCs) from bone marrow. When exposed to competing soluble differentiation signals, cells cultured in rectangles with increasing aspect ratio and in shapes with pentagonal symmetry but with different subcellular curvature-and with each occupying the same area-display different adipogenesis and osteogenesis profiles. The results reveal that geometric features that increase actomyosin contractility promote osteogenesis and are consistent with in vivo characteristics of the microenvironment of the differentiated cells. Cytoskeletal-disrupting pharmacological agents modulate shape-based trends in lineage commitment verifying the critical role of focal adhesion and myosin-generated contractility during differentiation. Microarray analysis and pathway inhibition studies suggest that contractile cells promote osteogenesis by enhancing c-Jun N-terminal kinase (JNK) and extracellular related kinase (ERK1/2) activation in conjunction with elevated wingless-type (Wnt) signaling. Taken together, this work points to the role that geometric shape cues can play in orchestrating the mechanochemical signals and paracrine/autocrine factors that can direct MSCs to appropriate fates.

title: Screening for Lung Cancer: U.S. Preventive Services Task Force Recommendation Statement

text: The U.S. Preventive Services Task Force (USPSTF) makes recommendations about the effectiveness of specific preventive care services for patients without related signs or symptoms. It bases its recommendations on the evidence of both the benefits and harms of the service and an assessment of the balance. The USPSTF does not consider the costs of providing a service in this assessment. The USPSTF recognizes that clinical decisions involve more considerations than evidence alone. Clinicians should understand the evidence but individualize decision making to the specific patient or situation. Similarly, the USPSTF notes that policy and coverage decisions involve considerations in addition to the evidence of clinical benefits and harms. Summary of Recommendation and Evidence The USPSTF recommends annual screening for lung cancer with low-dose computed tomography (LDCT) in adults aged 55 to 80 years who have a 30 pack-year smoking history and currently smoke or have quit within the past 15 years. Screening should be discontinued once a person has not smoked for 15 years or develops a health problem that substantially limits life expectancy or the ability or willingness to have curative lung surgery. (B recommendation) See the Clinical Considerations section for suggestions for implementation in practice. See the Figure for a summary of the recommendation and suggestions for clinical practice. Figure. Screening for lung cancer: clinical summary of U.S. Preventive Services Task Force recommendation. Appendix Table 1 describes the USPSTF grades, and Appendix Table 2 describes the USPSTF classification of levels of certainty about net benefit. Appendix Table 1. What the USPSTF Grades Mean and Suggestions for Practice Appendix Table 2. USPSTF Levels of Certainty Regarding Net Benefit Supplement. Consumer Fact Sheet. Rationale Importance Lung cancer is the third most common cancer and the leading cause of cancer-related death in the United States (1). The most important risk factor for lung cancer is smoking, which results in approximately 85% of all U.S. lung cancer cases (2). Although the prevalence of smoking has decreased, approximately 37% of U.S. adults are current or former smokers (2). The incidence of lung cancer increases with age and occurs most commonly in persons aged 55 years or older. Increasing age and cumulative exposure to tobacco smoke are the 2 most common risk factors for lung cancer. Lung cancer has a poor prognosis, and nearly 90% of persons with lung cancer die of the disease. However, early-stage nonsmall cell lung cancer (NSCLC) has a better prognosis and can be treated with surgical resection. Detection Most lung cancer cases are NSCLC, and most screening programs focus on the detection and treatment of early-stage NSCLC. Although chest radiography and sputum cytologic evaluation have been used to screen for lung cancer, LDCT has greater sensitivity for detecting early-stage cancer (3). Benefits of Detection and Early Treatment Although lung cancer screening is not an alternative to smoking cessation, the USPSTF found adequate evidence that annual screening for lung cancer with LDCT in a defined population of high-risk persons can prevent a substantial number of lung cancerrelated deaths. Direct evidence from a large, well-conducted, randomized, controlled trial (RCT) provides moderate certainty of the benefit of lung cancer screening with LDCT in this population (4). The magnitude of benefit to the person depends on that person's risk for lung cancer because those who are at highest risk are most likely to benefit. Screening cannot prevent most lung cancerrelated deaths, and smoking cessation remains essential. Harms of Detection and Early Intervention and Treatment The harms associated with LDCT screening include false-negative and false-positive results, incidental findings, overdiagnosis, and radiation exposure. False-positive LDCT results occur in a substantial proportion of screened persons; 95% of all positive results do not lead to a diagnosis of cancer. In a high-quality screening program, further imaging can resolve most false-positive results; however, some patients may require invasive procedures. The USPSTF found insufficient evidence on the harms associated with incidental findings. Overdiagnosis of lung cancer occurs, but its precise magnitude is uncertain. A modeling study performed for the USPSTF estimated that 10% to 12% of screen-detected cancer cases are overdiagnosedthat is, they would not have been detected in the patient's lifetime without screening. Radiation harms, including cancer resulting from cumulative exposure to radiation, vary depending on the age at the start of screening; the number of scans received; and the person's exposure to other sources of radiation, particularly other medical imaging. USPSTF Assessment The USPSTF concludes with moderate certainty that annual screening for lung cancer with LDCT is of moderate net benefit in asymptomatic persons who are at high risk for lung cancer based on age, total cumulative exposure to tobacco smoke, and years since quitting smoking. The moderate net benefit of screening depends on limiting screening to persons who are at high risk, the accuracy of image interpretation being similar to that found in the NLST (National Lung Screening Trial), and the resolution of most false-positive results without invasive procedures (4). Clinical Considerations Patient Population Under Consideration The risk for lung cancer increases with age and cumulative exposure to tobacco smoke and decreases with time since quitting smoking. The best evidence for the benefit of screening comes from the NLST, which enrolled adults aged 55 to 74 years who had at least a 30 pack-year smoking history and were current smokers or had quit within the past 15 years. As with all screening trials, the NLST tested a specific intervention over a finite period. Because initial eligibility extended through age 74 years and participants received 3 annual screening computed tomographic scans, the oldest participants in the trial were aged 77 years. The USPSTF used modeling studies to predict the benefits and harms of screening programs that use different screening intervals, age ranges, smoking histories, and times since quitting. A program that annually screens adults aged 55 to 80 years who have a 30 pack-year smoking history and currently smoke or have quit within the past 15 years is projected to have a reasonable balance of benefits and harms. The model assumes that persons who achieve 15 years of smoking cessation during the screening program discontinue screening. This model predicts the outcomes of continuing the screening program used in the NLST through age 80 years. Screening may not be appropriate for patients with substantial comorbid conditions, particularly those at the upper end of the screening age range. The NLST excluded persons who were unlikely to complete curative lung cancer surgery and those with medical conditions that posed a substantial risk for death during the 8-year trial. The baseline characteristics of the NLST showed a relatively healthy sample, and fewer than 10% of enrolled participants were older than 70 years (5). Persons with serious comorbid conditions may experience net harm, no net benefit, or at least substantially less net benefit. Similarly, persons who are unwilling to have curative lung surgery are unlikely to benefit from a screening program. Assessment of Risk Age, total exposure to tobacco smoke, and years since quitting smoking are important risk factors for lung cancer and were used to determine eligibility in the NLST. Other risk factors include specific occupational exposures, radon exposure, family history, and history of pulmonary fibrosis or chronic obstructive lung disease. The incidence of lung cancer is relatively low in persons younger than 50 years but increases with age, especially after age 60 years. In current and former smokers, age-specific incidence rates increase with age and cumulative exposure to tobacco smoke. Smoking cessation substantially reduces a person's risk for developing and dying of lung cancer. Among persons enrolled in the NLST, those who were at highest risk because of additional risk factors or a greater cumulative exposure to tobacco smoke experienced most of the benefit (6). A validated multivariate model showed that persons in the highest 60% of risk accounted for 88% of all deaths preventable by screening. Screening Tests Low-dose computed tomography has shown high sensitivity and acceptable specificity for the detection of lung cancer in high-risk persons. Chest radiography and sputum cytologic evaluation have not shown adequate sensitivity or specificity as screening tests. Therefore, LDCT is currently the only recommended screening test for lung cancer. Treatment Surgical resection is the current standard of care for localized NSCLC. This type of cancer is treated with surgical resection when possible and also with radiation and chemotherapy. Annual LDCT screening may not be useful for patients with life-limiting comorbid conditions or poor functional status who may not be candidates for surgery. Other Approaches to Prevention Smoking cessation is the most important intervention to prevent NSCLC. Advising smokers to stop smoking and preventing nonsmokers from being exposed to tobacco smoke are the most effective ways to decrease the morbidity and mortality associated with lung cancer. Current smokers should be informed of their continuing risk for lung cancer and offered cessation treatments. Screening with LDCT should be viewed as an adjunct to tobacco cessation interventions. Useful Resources Clinicians have many resources to help patients stop smoking. The Centers for Disease Control and Prevention has developed a Web site with many such resources, including information on tobacco quit lines, available in several languages (www.cdc.gov/tobacco/campaign/tips). Quit l

title: Conversion of vascular endothelial cells into multipotent stem-like cells

text: Mesenchymal stem cells can give rise to several cell types, but varying results depending on isolation methods and tissue source have led to controversies about their usefulness in clinical medicine. Here we show that vascular endothelial cells can transform into multipotent stem-like cells by an activin-like kinase-2 (ALK2) receptor–dependent mechanism. In lesions from individuals with fibrodysplasia ossificans progressiva (FOP), a disease in which heterotopic ossification occurs as a result of activating ALK2 mutations, or from transgenic mice expressing constitutively active ALK2, chondrocytes and osteoblasts expressed endothelial markers. Lineage tracing of heterotopic ossification in mice using a Tie2-Cre construct also suggested an endothelial origin of these cell types. Expression of constitutively active ALK2 in endothelial cells caused endothelial-to-mesenchymal transition and acquisition of a stem cell–like phenotype. Similar results were obtained by treatment of untransfected endothelial cells with the ligands transforming growth factor-β2 (TGF-β2) or bone morphogenetic protein-4 (BMP4) in an ALK2-dependent manner. These stem-like cells could be triggered to differentiate into osteoblasts, chondrocytes or adipocytes. We suggest that conversion of endothelial cells to stem-like cells may provide a new approach to tissue engineering.

title: Surgical Resection for Patients with Solid Brain Metastases: Current Status

text: Brain metastases occur in up to 40% of patients with cancer. Their management has been revolutionized in the last decade by three developments: improved imaging and detection of metastases, better treatment of systemic disease with the result that metastases occur more often; and improved surgical techniques including image-guided surgery to treat metastatic lesions. Class 1 data suggest that surgery is a better treatment for metastases than whole brain radiation. Other data suggest that metastases even in eloquent cortex can be removed safely. The complication rate is low and the recurrence rate is less than 10%. In general, indications for surgery include a mass with an unknown primary; a symptomatic mass including one in eloquent areas; a mass with considerable edema requiring high dose steroids; a mass greater than 3 cm; or patient preference when radiosurgery may also be an option. The question of radiosurgery or whole brain radiation as adjunct to surgical removal requires further evaluation.

title: CD200R/CD200 Inhibits Osteoclastogenesis: New Mechanism of Osteoclast Control by Mesenchymal Stem Cells in Human

text: Bone homeostasis is maintained by the balance between bone-forming osteoblasts and bone-degrading osteoclasts. Osteoblasts have a mesenchymal origin whereas osteoclasts belong to the myeloid lineage. Osteoclast and osteoblast communication occurs through soluble factors secretion, cell-bone interaction and cell-cell contact, which modulate their activities. CD200 is an immunoglobulin superfamilly member expressed on various types of cells including mesenchymal stem cells (MSCs). CD200 receptor (CD200R) is expressed on myeloid cells such as monocytes/macrophages. We assume that CD200 could be a new molecule involved in the control of osteoclastogenesis and could play a role in MSC-osteoclast communication in humans. In this study, we demonstrated that soluble CD200 inhibited the differentiation of osteoclast precursors as well as their maturation in bone-resorbing cells in vitro. Soluble CD200 did not modify the monocyte phenotype but inhibited the receptor activator of nuclear factor kappa-B ligand (RANKL) signaling pathway as well as the gene expression of osteoclast markers such as osteoclast-associated receptor (OSCAR) and nuclear factor of activated T cells cytoplasmic 1 (NFATc1). Moreover, MSCs inhibited osteoclast formation, which depended on cell-cell contact and was associated with CD200 expression on the MSC surface. Our results clearly demonstrate that MSCs, through the expression of CD200, play a major role in the regulation of bone resorption and bone physiology and that the CD200-CD200R couple could be a new target to control bone diseases.

title: Induction therapy with autologous mesenchymal stem cells in living-related kidney transplants: a randomized controlled trial.

text:
CONTEXT Antibody-based induction therapy plus calcineurin inhibitors (CNIs) reduce acute rejection rates in kidney recipients; however, opportunistic infections and toxic CNI effects remain challenging. Reportedly, mesenchymal stem cells (MSCs) have successfully treated graft-vs-host disease.
 OBJECTIVE To assess autologous MSCs as replacement of antibody induction for patients with end-stage renal disease who undergo ABO-compatible, cross-match-negative kidney transplants from a living-related donor.
 DESIGN, SETTING, AND PATIENTS One hundred fifty-nine patients were enrolled in this single-site, prospective, open-label, randomized study from February 2008-May 2009, when recruitment was completed.
 INTERVENTION Patients were inoculated with marrow-derived autologous MSC (1-2 x 10(6)/kg) at kidney reperfusion and two weeks later. Fifty-three patients received standard-dose and 52 patients received low-dose CNIs (80% of standard); 51 patients in the control group received anti-IL-2 receptor antibody plus standard-dose CNIs.
 MAIN OUTCOME MEASURES The primary measure was 1-year incidence of acute rejection and renal function (estimated glomerular filtration rate [eGFR]); the secondary measure was patient and graft survival and incidence of adverse events.
 RESULTS Patient and graft survival at 13 to 30 months was similar in all groups. After 6 months, 4 of 53 patients (7.5%) in the autologous MSC plus standard-dose CNI group (95% CI, 0.4%-14.7%; P = .04) and 4 of 52 patients (7.7%) in the low-dose group (95% CI, 0.5%-14.9%; P = .046) compared with 11 of 51 controls (21.6%; 95% CI, 10.5%-32.6%) had biopsy-confirmed acute rejection. None of the patients in either autologous MSC group had glucorticoid-resistant rejection, whereas 4 patients (7.8%) in the control group did (95% CI, 0.6%-15.1%; overall P = .02). Renal function recovered faster among both MSC groups showing increased eGFR levels during the first month after surgery than the control group. Patients receiving standard-dose CNI had a mean difference of 6.2 mL/min per 1.73 m(2) (95% CI, 0.4-11.9; P=.04) and those in the low-dose CNI of 10.0 mL/min per 1.73 m(2) (95% CI, 3.8-16.2; P=.002). Also, during the 1-year follow-up, combined analysis of MSC-treated groups revealed significantly decreased risk of opportunistic infections than the control group (hazard ratio, 0.42; 95% CI, 0.20-0.85, P=.02)   CONCLUSION Among patients undergoing renal transplant, the use of autologous MSCs compared with anti-IL-2 receptor antibody induction therapy resulted in lower incidence of acute rejection, decreased risk of opportunistic infection, and better estimated renal function at 1 year.
 TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT00658073.

title: Parathyroid Hormone Directs Bone Marrow Mesenchymal Cell Fate.

text: Intermittent PTH administration builds bone mass and prevents fractures, but its mechanism of action is unclear. We genetically deleted the PTH/PTHrP receptor (PTH1R) in mesenchymal stem cells using Prx1Cre and found low bone formation, increased bone resorption, and high bone marrow adipose tissue (BMAT). Bone marrow adipocytes traced to Prx1 and expressed classic adipogenic markers and high receptor activator of nuclear factor kappa B ligand (Rankl) expression. RANKL levels were also elevated in bone marrow supernatant and serum, but undetectable in other adipose depots. By cell sorting, Pref1+RANKL+ marrow progenitors were twice as great in mutant versus control marrow. Intermittent PTH administration to control mice reduced BMAT significantly. A similar finding was noted in male osteoporotic patients. Thus, marrow adipocytes exhibit osteogenic and adipogenic characteristics, are uniquely responsive to PTH, and secrete RANKL. These studies reveal an important mechanism for PTH's therapeutic action through its ability to direct mesenchymal cell fate.

title: Induction of stem-like cells with malignant properties by chronic exposure of human lung epithelial cells to single-walled carbon nanotubes

text:
BACKGROUND Carbon nanotubes (CNT) hold great promise to create new and better products for commercial and biomedical applications, but their long-term adverse health effects are a major concern. The objective of this study was to address human lung cancer risks associated with chronic pulmonary exposure to single-walled (SW) CNT through the fundamental understanding of cellular and molecular processes leading to carcinogenesis. We hypothesized that the acquisition of cancer stem cells (CSC), a subpopulation that drive tumor initiation and progression, may contribute to CNT carcinogenesis.
 METHODS Non-tumorigenic human lung epithelial cells were chronically exposed to well-dispersed SWCNT for a period of 6 months at the physiologically relevant concentration of 0.02 μg/cm2 surface area dose. Chronic SWCNT-exposed cells were evaluated for the presence of CSC-like cells under CSC-selective conditions of tumor spheres and side population (SP). CSC-like cells were isolated using fluorescence-activated cell sorting and were assessed for aggressive behaviors, including acquired apoptosis resistance and increased cell migration and invasion in vitro, and tumor-initiating capability in vivo. Non-small cell lung cancer cells served as a positive control.
 RESULTS We demonstrated for the first time the existence of CSC-like cells in all clones of chronic SWCNT-exposed lung epithelial cells. These CSC-like cells, in contrary to their non-CSC counterpart, possessed all biological features of lung CSC that are central to irreversible malignant transformation, self-renewal, aggressive cancer behaviors, and in vivo tumorigenesis. These cells also displayed aberrant stem cell markers, notably Nanog, SOX-2, SOX-17 and E-cadherin. Restored expression of tumor suppressor p53 abrogated CSC properties of CSC-like cells. Furthermore, we identified specific stem cell surface markers CD24low and CD133high that are associated with SWCNT-induced CSC formation and tumorigenesis.
 CONCLUSIONS Our findings provide new and compelling evidence for the acquisition of CSC-like cells induced by chronic SWCNT exposure, which are likely to be a major driving force for SWCNT tumorigenesis. Thus, our study supports prudent adoption of prevention strategies and implementation of exposure control for SWCNT. We also suggest that the detection of CSC and associated surface markers may provide an effective screening tool for prediction of the carcinogenic potential of SWCNT and related nanoparticles.

title: Markers of myocardial damage and inflammation in relation to long-term mortality in unstable coronary artery disease. FRISC Study Group. Fragmin during Instability in Coronary Artery Disease.

text:
BACKGROUND In patients with unstable coronary artery disease, there is a relation between the short-term risk of death and blood levels of troponin T (a marker of myocardial damage) and C-reactive protein and fibrinogen (markers of inflammation). Using information obtained during an extension of the follow-up period in the Fragmin during Instability in Coronary Artery Disease trial, we evaluated the usefulness of troponin T, C-reactive protein, and fibrinogen levels and other indicators of risk as predictors of the long-term risk of death from cardiac causes.
 METHODS Levels of C-reactive protein and fibrinogen at enrollment and the maximal level of troponin T during the first 24 hours after enrollment were analyzed in 917 patients included in a clinical trial of low-molecular-weight heparin in unstable coronary artery disease. The patients were followed for a mean of 37.0 months (range, 1.6 to 50.6).
 RESULTS During follow-up, 1.2 percent of the 173 patients with maximal blood troponin T levels of less than 0.06 microg per liter died of cardiac causes, as compared with 8.7 percent of the 367 patients with levels of 0.06 to 0.59 microg per liter and 15.4 percent of the 377 patients with levels of at least 0.60 microg per liter (P=0.007 and P=0.001, respectively). The rates of death from cardiac causes were 5.7 percent among the 314 patients with blood C-reactive protein levels of less than 2 mg per liter, 7.8 percent among the 294 with levels of 2 to 10 mg per liter, and 16.5 percent among the 309 with levels of more than 10 mg per liter (P=0.29 and P=0.001, respectively). The rates of death from cardiac causes were 5.4 percent among the 314 patients with blood fibrinogen levels of less than 3.4 g per liter, 12.0 percent among the 300 with levels of 3.4 to 3.9 g per liter, and 12.9 percent among the 303 with levels of at least 4.0 g per liter (P=0.004 and P=0.69, respectively). In a multivariate analysis, levels of troponin T and C-reactive protein were independent predictors of the risk of death from cardiac causes.
 CONCLUSIONS In unstable coronary artery disease, elevated levels of troponin T and C-reactive protein are strongly related to the long-term risk of death from cardiac causes. These markers are independent risk factors, and their effects are additive with respect to each other and other clinical indicators of risk.

title: Influence of smoking and plasma factors on patency of femoropopliteal vein grafts.

text:
OBJECTIVE To determine the effects of smoking, plasma lipids, lipoproteins, apolipoproteins, and fibrinogen on the patency of saphenous vein femoropopliteal bypass grafts at one year.
 DESIGN Prospective study of patients with saphenous vein femoropopliteal bypass grafts entered into a multicentre trial.
 SETTING Surgical wards, outpatient clinics, and home visits coordinated by two tertiary referral centres in London and Birmingham.
 PATIENTS 157 Patients (mean age 66.6 (SD 8.2) years), 113 with patent grafts and 44 with occluded grafts one year after bypass.
 MAIN OUTCOME MEASURE Cumulative percentage patency at one year.
 RESULTS Markers for smoking (blood carboxyhaemoglobin concentration (p less than 0.05) and plasma thiocyanate concentration (p less than 0.01) and plasma concentrations of fibrinogen (p less than 0.001) and apolipoproteins AI (p less than 0.04) and (a) (p less than 0.05) were significantly higher in patients with occluded grafts. Serum cholesterol concentrations were significantly higher in patients with grafts that remained patent one year after bypass (p less than 0.005). Analysis of the smoking markers indicated that a quarter of patients (40) were untruthful in their claims to have stopped smoking. Based on smoking markers, patency of grafts in smokers was significantly lower at one year by life table analysis than in non-smokers (63% v 84%, p less than 0.02). Patency was significantly higher by life table analysis in patients with a plasma fibrinogen concentration below the median than in those with a concentration above (90% v 57%, p less than 0.0002). Surprisingly, increased plasma low density lipoprotein cholesterol concentration was significantly associated with improved patency at one year (85%) at values above the median compared with patency (only 68%) at values in the lower half of the range (p less than 0.02).
 CONCLUSIONS Plasma fibrinogen concentration was the most important variable predicting graft occlusion, followed by smoking markers. A more forceful approach is needed to stop patients smoking; therapeutic measures to improve patency of vein grafts should focus on decreasing plasma fibrinogen concentration rather than serum cholesterol concentration.

title: Leptin-receptor-expressing mesenchymal stromal cells represent the main source of bone formed by adult bone marrow.

text: Studies of the identity and physiological function of mesenchymal stromal cells (MSCs) have been hampered by a lack of markers that permit both prospective identification and fate mapping in vivo. We found that Leptin Receptor (LepR) is a marker that highly enriches bone marrow MSCs. Approximately 0.3% of bone marrow cells were LepR(+) , 10% of which were CFU-Fs, accounting for 94% of bone marrow CFU-Fs. LepR(+) cells formed bone, cartilage, and adipocytes in culture and upon transplantation in vivo. LepR(+) cells were Scf-GFP(+), Cxcl12-DsRed(high), and Nestin-GFP(low), markers which also highly enriched CFU-Fs, but negative for Nestin-CreER and NG2-CreER, markers which were unlikely to be found in CFU-Fs. Fate-mapping showed that LepR(+) cells arose postnatally and gave rise to most bone and adipocytes formed in adult bone marrow, including bone regenerated after irradiation or fracture. LepR(+) cells were quiescent, but they proliferated after injury. Therefore, LepR(+) cells are the major source of bone and adipocytes in adult bone marrow.

title: Detection, characterization, and spontaneous differentiation in vitro of very small embryonic-like putative stem cells in adult mammalian ovary.

text: The present study was undertaken to detect, characterize, and study differentiation potential of stem cells in adult rabbit, sheep, monkey, and menopausal human ovarian surface epithelium (OSE). Two distinct populations of putative stem cells (PSCs) of variable size were detected in scraped OSE, one being smaller and other similar in size to the surrounding red blood cells in the scraped OSE. The smaller 1-3 μm very small embryonic-like PSCs were pluripotent in nature with nuclear Oct-4 and cell surface SSEA-4, whereas the bigger 4-7 μm cells with cytoplasmic localization of Oct-4 and minimal expression of SSEA-4 were possibly the tissue committed progenitor stem cells. Pluripotent gene transcripts of Oct-4, Oct-4A, Nanog, Sox-2, TERT, and Stat-3 in human and sheep OSE were detected by reverse transcriptase-polymerase chain reaction. The PSCs underwent spontaneous differentiation into oocyte-like structures, parthenote-like structures, embryoid body-like structures, cells with neuronal-like phenotype, and embryonic stem cell-like colonies, whereas the epithelial cells transformed into mesenchymal phenotype by epithelial-mesenchymal transition in 3 weeks of OSE culture. Germ cell markers like c-Kit, DAZL, GDF-9, VASA, and ZP4 were immuno-localized in oocyte-like structures. In conclusion, as opposed to the existing view of OSE being a bipotent source of oocytes and granulosa cells, mammalian ovaries harbor distinct very small embryonic-like PSCs and tissue committed progenitor stem cells population that have the potential to develop into oocyte-like structures in vitro, whereas mesenchymal fibroblasts appear to form supporting granulosa-like somatic cells. Research at the single-cell level, including complete gene expression profiling, is required to further confirm whether postnatal oogenesis is a conserved phenomenon in adult mammals.


query: Lice attenuated SIV vaccines induce a stronger antigen-specific T cell response in lymph node cells.

title: Lymph node T cell responses predict the efficacy of live attenuated SIV vaccines

text: Live attenuated simian immunodeficiency virus (SIV) vaccines (LAVs) remain the most efficacious of all vaccines in nonhuman primate models of HIV and AIDS, yet the basis of their robust protection remains poorly understood. Here we show that the degree of LAV-mediated protection against intravenous wild-type SIVmac239 challenge strongly correlates with the magnitude and function of SIV-specific, effector-differentiated T cells in the lymph node but not with the responses of such T cells in the blood or with other cellular, humoral and innate immune parameters. We found that maintenance of protective T cell responses is associated with persistent LAV replication in the lymph node, which occurs almost exclusively in follicular helper T cells. Thus, effective LAVs maintain lymphoid tissue-based, effector-differentiated, SIV-specific T cells that intercept and suppress early wild-type SIV amplification and, if present in sufficient frequencies, can completely control and perhaps clear infection, an observation that provides a rationale for the development of safe, persistent vectors that can elicit and maintain such responses.

title: Nanoparticle conjugation of CpG enhances adjuvancy for cellular immunity and memory recall at low dose.

text: In subunit vaccines, strong CD8(+) T-cell responses are desired, yet they are elusive at reasonable adjuvant doses. We show that targeting adjuvant to the lymph node (LN) via ultrasmall polymeric nanoparticles (NPs), which rapidly drain to the LN after intradermal injection, greatly enhances adjuvant efficacy at low doses. Coupling CpG-B or CpG-C oligonucleotides to NPs led to better dual-targeting of adjuvant and antigen (codelivered on separate NPs) in cross-presenting dendritic cells compared with free adjuvant. This led to enhanced dendritic cell maturation and T helper 1 (Th1)-cytokine secretion, in turn driving stronger effector CD8(+) T-cell activation with enhanced cytolytic profiles and, importantly, more powerful memory recall. With only 4 μg CpG, NP-CpG-B could substantially protect mice from syngeneic tumor challenge, even after 4 mo of vaccination, compared with free CpG-B. Together, these results show that nanocarriers can enhance vaccine efficacy at a low adjuvant dose for inducing potent and long-lived cellular immunity.

title: Apoptosis occurs predominantly in bystander cells and not in productively infected cells of HIV- and SIV-infected lymph nodes

text: Although 13 years have passed since identification of human immunodeficiency virus-1 (HIV-1) as the cause of AIDS, we do not yet know how HIV kills its primary target, the T cell that carries the CD4 antigen. We and others have shown an increase in the percentage of apoptotic cells among circulating CD4+ (and CD8+) T cells of HIV-seropositive individuals and an increase in frequency of apoptosis with disease progression. However, it is not known if this apoptosis occurs in infected or uninfected T cells. We show here, using in situ labelling of lymph nodes from HIV-infected children and SIV-infected macaques, that apoptosis occurs predominantly in bystander cells and not in the productively infected cells themselves. These data have implications for pathogenesis and therapy, namely, arguing that rational drug therapy may involve combination agents targeting viral replication in infected cells and apoptosis of uninfected cells.

title: Fusion proteins for versatile antigen targeting to cell surface receptors reveal differential capacity to prime immune responses.

text: Targeting of proteins to APCs is an attractive strategy for eliciting adaptive immune responses. However, the relationship between the choice of the targeted receptor and the quality and quantity of responses remains poorly understood. We describe a strategy for expression of Ags including hydrophobic proteins as soluble fusion proteins that are optimized for proteasome-dependent MHC class I-restricted cross-presentation and form stable complexes with a wide variety of targeting Abs. Upon s.c. immunization, these complexes were initially taken up by CD169+ lymph node subcapsular sinus macrophages. In the OVA model system, receptor-targeted antigenic complexes primed specific T and B cell responses in vitro and in vivo at least 100-fold more efficiently than Ag alone. Comparison of 10 targeting receptors allowed us to establish a ranking with respect to priming of CD8+ T cell responses and demonstrated striking differences with respect to the relative efficacy of CD8+ and CD4+ T cell subset and B cell priming. The described fusion proteins should help in developing optimized strategies for targeted delivery of protein Ags in the context of tolerization or vaccination.

title: CD169-positive macrophages dominate antitumor immunity by crosspresenting dead cell-associated antigens.

text: The generation of tumor-directed cytotoxic T lymphocytes is considered crucial for the induction of antitumor immunity. To activate these CD8(+) T cells, antigen-presenting cells (APCs) must initially acquire tumor cell-associated antigens. The major source of tumor antigens is dead tumor cells, but little is known about how APCs in draining lymph nodes acquire and crosspresent these antigens. Here we show that CD169(+) macrophages phagocytose dead tumor cells transported via lymphatic flow and subsequently crosspresent tumor antigens to CD8(+) T cells. Subcutaneous immunization with irradiated tumor cells protects mice from syngenic tumor. However, tumor antigen-specific CD8(+) T cell activation and subsequent antitumor immunity are severely impaired in mice depleted with CD169(+) macrophages. Neither migratory dendritic cells (DCs) nor lymph node-resident conventional DCs are essential for the crosspresentation of tumor antigens. Thus, we have identified CD169(+) macrophages as lymph node-resident APCs dominating early activation of tumor antigen-specific CD8(+) T cells.

title: Exploiting lymphatic transport and complement activation in nanoparticle vaccines

text: Antigen targeting and adjuvancy schemes that respectively facilitate delivery of antigen to dendritic cells and elicit their activation have been explored in vaccine development. Here we investigate whether nanoparticles can be used as a vaccine platform by targeting lymph node–residing dendritic cells via interstitial flow and activating these cells by in situ complement activation. After intradermal injection, interstitial flow transported ultra-small nanoparticles (25 nm) highly efficiently into lymphatic capillaries and their draining lymph nodes, targeting half of the lymph node–residing dendritic cells, whereas 100-nm nanoparticles were only 10% as efficient. The surface chemistry of these nanoparticles activated the complement cascade, generating a danger signal in situ and potently activating dendritic cells. Using nanoparticles conjugated to the model antigen ovalbumin, we demonstrate generation of humoral and cellular immunity in mice in a size- and complement-dependent manner.

title: Maternal alloantigens promote the development of tolerogenic fetal regulatory T cells in utero.

text: As the immune system develops, T cells are selected or regulated to become tolerant of self antigens and reactive against foreign antigens. In mice, the induction of such tolerance is thought to be attributable to the deletion of self-reactive cells. Here, we show that the human fetal immune system takes advantage of an additional mechanism: the generation of regulatory T cells (Tregs) that suppress fetal immune responses. We find that substantial numbers of maternal cells cross the placenta to reside in fetal lymph nodes, inducing the development of CD4+CD25highFoxP3+ Tregs that suppress fetal antimaternal immunity and persist at least until early adulthood. These findings reveal a form of antigen-specific tolerance in humans, induced in utero and probably active in regulating immune responses after birth.

title: Chimeric Antigen Receptor-Redirected Regulatory T Cells Suppress Experimental Allergic Airway Inflammation, a Model of Asthma

text: Cellular therapy with chimeric antigen receptor (CAR)-redirected cytotoxic T cells has shown impressive efficacy in the treatment of hematologic malignancies. We explored a regulatory T cell (Treg)-based therapy in the treatment of allergic airway inflammation, a model for asthma, which is characterized by an airway hyper-reactivity (AHR) and a chronic, T helper-2 (Th2) cell-dominated immune response to allergen. To restore the immune balance in the lung, we redirected Tregs by a CAR toward lung epithelia in mice upon experimentally induced allergic asthma, closely mimicking the clinical situation. Adoptively transferred CAR Tregs accumulated in the lung and in tracheobronchial lymph nodes, reduced AHR and diminished eosinophilic airway inflammation, indicated by lower cell numbers in the bronchoalveolar lavage fluid and decreased cell infiltrates in the lung. CAR Treg cells furthermore prevented excessive pulmonary mucus production as well as increase in allergen-specific IgE and Th2 cytokine levels in exposed animals. CAR Tregs were more efficient in controlling asthma than non-modified Tregs, indicating the pivotal role of specific Treg cell activation in the affected organ. Data demonstrate that lung targeting CAR Treg cells ameliorate key features of experimental airway inflammation, paving the way for cell therapy of severe allergic asthma.

title: CD169+ MACROPHAGES PRESENT LIPID ANTIGENS TO MEDIATE EARLY ACTIVATION OF INVARIANT NKT CELLS IN LYMPH NODES

text: Invariant natural killer T cells (iNKT cells) are involved in the host defense against microbial infection. Although it is known that iNKT cells recognize glycolipids presented by CD1d, how and where they encounter antigen in vivo remains unclear. Here we used multiphoton microscopy to visualize the dynamics and activation of iNKT cells in lymph nodes. After antigen administration, iNKT cells became confined in a CD1d-dependent manner in close proximity to subcapsular sinus CD169(+) macrophages. These macrophages retained, internalized and presented lipid antigen and were required for iNKT cell activation, cytokine production and population expansion. Thus, CD169(+) macrophages can act as true antigen-presenting cells controlling early iNKT cell activation and favoring the fast initiation of immune responses.

title: Conventional and monocyte-derived CD11b(+) dendritic cells initiate and maintain T helper 2 cell-mediated immunity to house dust mite allergen.

text: Dendritic cells (DCs) are crucial for mounting allergic airway inflammation, but it is unclear which subset of DCs performs this task. By using CD64 and MAR-1 staining, we reliably separated CD11b(+) monocyte-derived DCs (moDCs) from conventional DCs (cDCs) and studied antigen uptake, migration, and presentation assays of lung and lymph node (LN) DCs in response to inhaled house dust mite (HDM). Mainly CD11b(+) cDCs but not CD103(+) cDCs induced T helper 2 (Th2) cell immunity in HDM-specific T cells in vitro and asthma in vivo. Studies in Flt3l(-/-) mice, lacking all cDCs, revealed that moDCs were also sufficient to induce Th2 cell-mediated immunity but only when high-dose HDM was given. The main function of moDCs was the production of proinflammatory chemokines and allergen presentation in the lung during challenge. Thus, we have identified migratory CD11b(+) cDCs as the principal subset inducing Th2 cell-mediated immunity in the LN, whereas moDCs orchestrate allergic inflammation in the lung.

title: Migratory dendritic cells transfer antigen to a lymph node-resident dendritic cell population for efficient CTL priming.

text: Skin dendritic cells (DCs) are thought to act as key initiators of local T cell immunity. Here we show that after skin infection with herpes simplex virus (HSV), cytotoxic T lymphocyte (CTL) activation required MHC class I-restricted presentation by nonmigratory CD8(+) DCs rather than skin-derived DCs. Despite a lack of direct presentation by migratory DCs, blocking their egress from infected skin substantially inhibited class I-restricted presentation and HSV-specific CTL responses. These results support the argument for initial transport of antigen by migrating DCs, followed by its transfer to the lymphoid-resident DCs for presentation and CTL priming. Given that relatively robust CTL responses were seen with small numbers of skin-emigrant DCs, we propose that this inter-DC antigen transfer functions to amplify presentation across a larger network of lymphoid-resident DCs for efficient T cell activation.

title: Interleukin 6 plays a key role in the development of antigen-induced arthritis.

text: To investigate the direct role of interleukin (IL) 6 in the development of rheumatoid arthritis, IL-6-deficient (IL-6 -/-) mice were backcrossed for eight generations into C57BL/6 mice, a strain of mice with a genetic background of susceptibility for antigen-induced arthritis (AIA). Both histological and immunological comparisons were made between IL-6-deficient (IL-6 -/-) mice and wild-type (IL-6 +/+) littermates after the induction of AIA. Although all IL-6 +/+ mice developed severe arthritis, only mild arthritis was observed in IL-6 -/- mice. Safranin O staining demonstrated that articular cartilage was well preserved in IL-6 -/- mice, whereas it was destroyed completely in IL-6 +/+ mice. In addition, comparable mRNA expression for both IL-1beta and tumor necrosis factor alpha, but not for IL-6, was detected in the inflamed joints of IL-6 -/- mice, suggesting that IL-6 may play a more crucial role in cartilage destruction than either IL-1beta or tumor necrosis factor alpha. In immunological comparisons, both antigen-specific in vitro proliferative response in lymph node cells and in vivo antibody production were elicited in IL-6 -/- mice, but they were reduced to less than half of that found in IL-6 +/+ mice. Lymph node cells of IL-6 -/- mice produced many more Th2 cytokines than did IL-6 +/+ mice with either antigen-specific or nonspecific stimulation in in vitro culture. Taken together, these results indicate that IL-6 may play a key role in the development of AIA at the inductive as well as the effector phase, and the blockade of IL-6 is possibly beneficial in the treatment of rheumatoid arthritis.

title: Subcapsular encounter and complement-dependent transport of immune complexes by lymph node B cells

text: The mechanism of B cell–antigen encounter in lymphoid tissues is incompletely understood. It is also unclear how immune complexes are transported to follicular dendritic cells. Here, using real-time two-photon microscopy we noted rapid delivery of immune complexes through the lymph to macrophages in the lymph node subcapsular sinus. B cells captured immune complexes by a complement receptor–dependent mechanism from macrophage processes that penetrated the follicle and transported the complexes to follicular dendritic cells. Furthermore, cognate B cells captured antigen-containing immune complexes from macrophage processes and migrated to the T zone. Our findings identify macrophages lining the subcapsular sinus as an important site of B cell encounter with immune complexes and show that intrafollicular B cell migration facilitates the transport of immune complexes as well as encounters with cognate antigen.

title: Cell-mediated immunity and antibody responses elicited by attenuated Salmonella enterica Serovar Typhi strains used as live oral vaccines in humans.

text: The development of improved typhoid vaccines is a high global public health priority. However, their development has been hampered by a lack of information regarding the specific determinants of protective immunity to Salmonella enterica serovar Typhi (S. Typhi) infection in humans. Although antibodies to S. Typhi O, H, and Vi appear to be involved in protection against S. Typhi infection, it is unknown whether such antibodies mediate protection, act in conjunction with other adaptive responses, or serve as a surrogate for the presence of other, more dominant protective immune responses (e.g., cell-mediated immunity [CMI]). CMI responses elicited by immunization of subjects with attenuated S. Typhi oral vaccines include lymphoproliferation; production of type 1 cytokines (e.g., interferon- gamma and tumor necrosis factor- alpha ); and classical major histocompatibility complex (MHC) class Ia-restricted and novel, nonclassical MHC class Ib (human leukocyte antigen [HLA]-E)-restricted CD8(+) cytotoxic T cell responses. In sum, human immunity to S. Typhi elicited by immunization is unexpectedly broad and complex. However, the immunologic correlates of protection remain largely undefined.

title: Human Cytomegalovirus-Encoded Interleukin-10 Homolog Inhibits Maturation of Dendritic Cells and Alters Their Functionality

text: Interleukin-10 (IL-10) suppresses the maturation and cytokine production of dendritic cells (DCs), key regulators of adaptive immunity, and prevents the activation and polarization of naïve T cells towards protective gamma interferon-producing effectors. We hypothesized that human cytomegalovirus (HCMV) utilizes its viral IL-10 homolog (cmvIL-10) to attenuate DC functionality, thereby subverting the efficient induction of antiviral immune responses. RNA and protein analyses demonstrated that the cmvIL-10 gene was expressed with late gene kinetics. Treatment of immature DCs (iDCs) with supernatant from HCMV-infected cultures inhibited both the lipopolysaccharide-induced DC maturation and proinflammatory cytokine production. These inhibitory effects were specifically mediated through the IL-10 receptor and were not observed when DCs were treated with supernatant of cells infected with a cmvIL-10-knockout mutant. Incubation of iDCs with recombinant cmvIL-10 recapitulated the inhibition of maturation. Furthermore, cmvIL-10 had pronounced long-term effects on those DCs that could overcome this inhibition of maturation. It enhanced the migration of mature DCs (mDCs) towards the lymph node homing chemokine but greatly reduced their cytokine production. The inability of mDCs to secrete IL-12 was maintained, even when they were restimulated by the activated T-cell signal CD40 ligand in the absence of cmvIL-10. Importantly, cmvIL-10 potentiates these anti-inflammatory effects, at least partially, by inducing endogenous cellular IL-10 expression in DCs. Collectively, we show that cmvIL-10 causes long-term functional alterations at all stages of DC activation.

title: Antigen availability determines CD8⁺ T cell-dendritic cell interaction kinetics and memory fate decisions.

text: T cells are activated by antigen (Ag)-bearing dendritic cells (DCs) in lymph nodes in three phases. The duration of the initial phase of transient, serial DC-T cell interactions is inversely correlated with Ag dose. The second phase, characterized by stable DC-T cell contacts, is believed to be necessary for full-fledged T cell activation. Here we have shown that this is not the case. CD8⁺ T cells interacting with DCs presenting low-dose, short-lived Ag did not transition to phase 2, whereas higher Ag dose yielded phase 2 transition. Both antigenic constellations promoted T cell proliferation and effector differentiation but yielded different transcriptome signatures at 12 hr and 24 hr. T cells that experienced phase 2 developed long-lived memory, whereas conditions without stable contacts yielded immunological amnesia. Thus, T cells make fate decisions within hours after Ag exposure, resulting in long-term memory or abortive effector responses, correlating with T cell-DCs interaction kinetics.

title: Distinct memory CD4+ T cells with commitment to T follicular helper- and T helper 1-cell lineages are generated after acute viral infection.

text: CD4(+) T follicular helper (Tfh) cells provide the required signals to B cells for germinal center reactions that are necessary for long-lived antibody responses. However, it remains unclear whether there are CD4(+) memory T cells committed to the Tfh cell lineage after antigen clearance. By using adoptive transfer of antigen-specific memory CD4(+) T cell subpopulations in the lymphocytic choriomeningitis virus infection model, we found that there are distinct memory CD4(+) T cell populations with commitment to either Tfh- or Th1-cell lineages. Our conclusions are based on gene expression profiles, epigenetic studies, and phenotypic and functional analyses. Our findings indicate that CD4(+) memory T cells "remember" their previous effector lineage after antigen clearance, being poised to reacquire their lineage-specific effector functions upon antigen reencounter. These findings have important implications for rational vaccine design, where improving the generation and engagement of memory Tfh cells could be used to enhance vaccine-induced protective immunity.

title: Cytokine production patterns and lymphoproliferative responses in volunteers orally immunized with attenuated vaccine strains of Salmonella typhi.

text: New recombinant strains of attenuated Salmonella typhi used as live oral vaccines elicit potent immune responses. This study examined the patterns of cytokine production and proliferation to specific S. typhi antigens in subjects orally immunized with attenuated S. typhi vaccines CVD 906, CVD 908, and CVD 908 expressing the circumsporozoite protein of Plasmodium falciparum. After immunization, sensitized lymphocytes were found in subjects' blood that exhibited significantly increased proliferative responses and interferon-gamma production to purified S. typhi flagella when compared with preimmunization levels. Significant negative correlations were observed between interleukin-4 production and both interferon-gamma production and proliferation to S. typhi flagella. These results demonstrate that oral immunization with attenuated S. typhi strains alone or with those carrying a foreign gene elicits strong systemic cell-mediated immunity to purified S. typhi antigens, including the production of cytokines compatible with T1-type responses.

title: The Immune Response to Melanoma Is Limited by Thymic Selection of Self-Antigens

text: The expression of melanoma-associated antigens (MAA) being limited to normal melanocytes and melanomas, MAAs are ideal targets for immunotherapy and melanoma vaccines. As MAAs are derived from self, immune responses to these may be limited by thymic tolerance. The extent to which self-tolerance prevents efficient immune responses to MAAs remains unknown. The autoimmune regulator (AIRE) controls the expression of tissue-specific self-antigens in thymic epithelial cells (TECs). The level of antigens expressed in the TECs determines the fate of auto-reactive thymocytes. Deficiency in AIRE leads in both humans (APECED patients) and mice to enlarged autoreactive immune repertoires. Here we show increased IgG levels to melanoma cells in APECED patients correlating with autoimmune skin features. Similarly, the enlarged T cell repertoire in AIRE(-/-) mice enables them to mount anti-MAA and anti-melanoma responses as shown by increased anti-melanoma antibodies, and enhanced CD4(+) and MAA-specific CD8(+) T cell responses after melanoma challenge. We show that thymic expression of gp100 is under the control of AIRE, leading to increased gp100-specific CD8(+) T cell frequencies in AIRE(-/-) mice. TRP-2 (tyrosinase-related protein), on the other hand, is absent from TECs and consequently TRP-2 specific CD8(+) T cells were found in both AIRE(-/-) and AIRE(+/+) mice. This study emphasizes the importance of investigating thymic expression of self-antigens prior to their inclusion in vaccination and immunotherapy strategies.

title: CD64 expression distinguishes monocyte-derived and conventional dendritic cells and reveals their distinct role during intramuscular immunization.

text: Although most vaccines are administered i.m., little is known about the dendritic cells (DCs) that are present within skeletal muscles. In this article, we show that expression of CD64, the high-affinity IgG receptor FcγRI, distinguishes conventional DCs from monocyte-derived DCs (Mo-DCs). By using such a discriminatory marker, we defined the distinct DC subsets that reside in skeletal muscles and identified their migratory counterparts in draining lymph nodes (LNs). We further used this capability to analyze the functional specialization that exists among muscle DCs. After i.m. administration of Ag adsorbed to alum, we showed that alum-injected muscles contained large numbers of conventional DCs that belong to the CD8α(+)- and CD11b(+)-type DCs. Both conventional DC types were capable of capturing Ag and of migrating to draining LNs, where they efficiently activated naive T cells. In alum-injected muscles, Mo-DCs were as numerous as conventional DCs, but only a small fraction migrated to draining LNs. Therefore, alum by itself poorly induces Mo-DCs to migrate to draining LNs. We showed that addition of small amounts of LPS to alum enhanced Mo-DC migration. Considering that migratory Mo-DCs had, on a per cell basis, a higher capacity to induce IFN-γ-producing T cells than conventional DCs, the addition of LPS to alum enhanced the overall immunogenicity of Ags presented by muscle-derived DCs. Therefore, a full understanding of the role of adjuvants during i.m. vaccination needs to take into account the heterogeneous migratory and functional behavior of muscle DCs and Mo-DCs revealed in this study.