bluuebunny/crossref_metadata_2025 huggingface dataset:
Detection and Long-Term In Vivo Monitoring of Individual Tumor-Specific T Cell Clones in Patients with Metastatic Melanoma
Authors: Michalek Jaroslav , Kocak Ivo , Fait Vuk , Zaloudik Jan , Hajek Roman
Published: April 2014

We investigated the presence of individual melanoma-specific T cell clones in patients with metastatic melanoma. Ten patients were examined for the presence of melanoma-reactive T cells using dendritic cells loaded with autologous tumor cells. Their specificity was tested using nonradioactive cytotoxicity test. Individual immunodominant T cell clones were identified by the clonotypic assay that combines in vitro cell culture, immunomagnetic sorting of activated IFN-γ+ T cells, TCRβ locus-anchored RT-PCR, and clonotypic quantitative PCR. All patients had detectable melanoma-reactive T cells in vitro. Expanded melanoma-reactive T cells demonstrated specific cytotoxic effect against autologous tumor cells in vitro. Three patients experienced objective responses, and their clinical responses were closely associated with the in vivo expansion and long-term persistence of individual CD8+ T cell clones with frequencies of 10−6 to 10−3 of all circulating CD8+ T cells. Five patients with progressive disease experienced no or temporary presence of circulating melanoma-reactive T cell clones. Thus, circulating immunodominant CD8+ T cell clones closely correlate with clinical outcome in patients with metastatic melanoma.
Redundant Role for Early Growth Response Transcriptional Regulators in Thymocyte Differentiation and Survival
Authors: Carter John H. , Lefebvre Juliet M. , Wiest David L. , Tourtellotte Warren G.
Published: April 2014

The early growth response (Egr) family of transcriptional regulators consists of four proteins that share highly conserved DNA-binding domains. In many cell types, they are coexpressed and appear to have cooperative roles in regulating gene expression during growth and differentiation. Three Egr proteins, Egr1, Egr2, and Egr3, are induced during thymocyte differentiation in response to pre-TCR signaling, suggesting they may be critical for some aspects of pre-TCR-mediated differentiation. Indeed, enforced expression of Egr proteins in developing thymocytes can recapitulate some aspects of pre-TCR signaling, but the mechanisms by which they contribute to β-selection are still poorly understood. Egr3 stimulates proliferation of β-selected thymocytes, and Egr3-deficient mice have hypocellular thymuses, defects in proliferation, and impaired progression from double-negative 3 to double-negative 4. Surprisingly, Egr1-deficient mice exhibit normal β-selection, indicating that the functions of Egr1 during β-selection are likely compensated by other Egr proteins. In this study, we show that mice lacking both Egr1 and Egr3 exhibit a more severe thymic atrophy and impairment of thymocyte differentiation than mice lacking either Egr1 or Egr3. This is due to a proliferation defect and cell-autonomous increase in apoptosis, indicating that Egr1 and Egr3 cooperate to promote thymocyte survival. Microarray analysis of deregulated gene expression in immature thymocytes lacking both Egr1 and Egr3 revealed a previously unknown role for Egr proteins in the maintenance of cellular metabolism, providing new insight into the function of these molecules during T cell development.
CD4+CD25+ T Regulatory Cells Dominate Multiple Immune Evasion Mechanisms in Early but Not Late Phases of Tumor Development in a B Cell Lymphoma Model
Authors: Elpek Kutlu G. , Lacelle Chantale , Singh Narendra P. , Yolcu Esma S. , Shirwan Haval
Published: April 2014

Tumors use a complex set of direct and indirect mechanisms to evade the immune system. Naturally arising CD4+CD25+FoxP3+ T regulatory (Treg) cells have been implicated recently in tumor immune escape mechanism, but the relative contribution of these cells to overall tumor progression compared with other immune evasion mechanisms remains to be elucidated. Using the A20 B cell lymphoma as a transplantable tumor model, we demonstrate that this tumor employs multiple direct (expression of immunoinhibitory molecule PD-L1, IDO, and IL-10, and lack of expression of CD80 costimulatory molecule) and indirect (down-regulation of APC function and induction of Treg cells) immune evasion mechanisms. Importantly, Treg cells served as the dominant immune escape mechanism early in tumor progression because the physical elimination of these cells before tumor challenge resulted in tumor-free survival in 70% of mice, whereas their depletion in animals with established tumors had no therapeutic effect. Therefore, our data suggest that Treg cells may serve as an important therapeutic target for patients with early stages of cancer and that more vigorous combinatorial approaches simultaneously targeting multiple immune evasion as well as immunosurveillance mechanisms for the generation of a productive immune response against tumor may be required for effective immunotherapy in patients with advanced disease.
CD103− and CD103+ Bronchial Lymph Node Dendritic Cells Are Specialized in Presenting and Cross-Presenting Innocuous Antigen to CD4+ and CD8+ T Cells
Authors: del Rio Maria-Luisa , Rodriguez-Barbosa Jose-Ignacio , Kremmer Elisabeth , Förster Reinhold
Published: April 2014

Dendritic cells (DC) are able to capture, process, and present exogenous Ag to CD8+ T lymphocytes through MHC class I, a process referred to as cross-presentation. In this study, we demonstrate that CD103+ (CD11chighCD11blow) and CD103− (CD11cintCD11bhigh) DC residing in the lung-draining bronchial lymph node (brLN) have evolved to acquire opposing functions in presenting innocuous inhaled Ag. Thus, under tolerogenic conditions, CD103− DC are specialized in presenting innocuous Ag to CD4+ T cells, whereas CD103+ DC, which do not express CD8α, are specialized in presenting Ag exclusively to CD8+ T cells. In CCR7-deficient but not in plt/plt mice, Ag-carrying CD103+ DC are largely absent in the brLN, although CD103+ DC are present in the lung of CCR7-deficient mice. As a consequence, adoptively transferred CD8+ T cells can be activated under tolerizing conditions in plt/plt but not in CCR7-deficient mice. These data reveal that CD103+ brLN DC are specialized in cross-presenting innocuous inhaled Ag in vivo. Because these cells are largely absent in CCR7−/− mice, our findings strongly suggest that brLN CD103+ DC are lung-derived and that expression of CCR7 is required for their migration from the lung into its draining lymph node.
Murine Dendritic Cell Type I IFN Production Induced by Human IgG-RNA Immune Complexes Is IFN Regulatory Factor (IRF)5 and IRF7 Dependent and Is Required for IL-6 Production
Authors: Yasuda Kei , Richez Christophe , Maciaszek Joseph W. , Agrawal Neerja , Akira Shizuo , Marshak-Rothstein Ann , Rifkin Ian R.
Published: April 2014

Dendritic cell (DC) activation by nucleic acid-containing IgG complexes is implicated in systemic lupus erythematosus (SLE) pathogenesis. However, it has been difficult to definitively examine the receptors and signaling pathways by which this activation is mediated. Because mouse FcγRs recognize human IgG, we hypothesized that IgG from lupus patients might stimulate mouse DCs, thereby facilitating this analysis. In this study, we show that sera and purified IgG from lupus patients activate mouse DCs to produce IFN-α, IFN-β, and IL-6 and up-regulate costimulatory molecules in a FcγR-dependent manner. This activation is only seen in sera with reactivity against ribonucleoproteins and is completely dependent on TLR7 and the presence of RNA. As anticipated, IFN regulatory factor (IRF)7 is required for IFN-α and IFN-β production. Unexpectedly, however, IRF5 plays a critical role in IFN-α and IFN-β production induced not only by RNA-containing immune complexes but also by conventional TLR7 and TLR9 ligands. Moreover, DC production of IL-6 induced by these stimuli is dependent on a functional type I IFNR, indicating the need for a type I IFN-dependent feedback loop in the production of inflammatory cytokines. This system may also prove useful for the study of receptors and signaling pathways used by immune complexes in other human diseases.
The CD28/CTLA-4-B7 Signaling Pathway Is Involved in Both Allergic Sensitization and Tolerance Induction to Orally Administered Peanut Proteins
Authors: van Wijk Femke , Nierkens Stefan , de Jong Wilco , Wehrens Ellen J. M. , Boon Louis , van Kooten Peter , Knippels Léon M. J. , Pieters Raymond
Published: April 2014

Dendritic cells are believed to play an essential role in regulating the balance between immunogenic and tolerogenic responses to mucosal Ags by controlling T cell differentiation and activation via costimulatory and coinhibitory signals. The CD28/CTLA-4-CD80/CD86 signaling pathway appears to be one of the most important regulators of T cell responses but its exact role in responses to orally administered proteins remains to be elucidated. In the present study, the involvement of the CD28/CTLA-4-CD80/CD86 costimulatory pathway in the induction of allergic sensitization and oral tolerance to peanut proteins was investigated. In both an established C3H/HeOuJ mouse model of peanut hypersensitivity and an oral tolerance model to peanut, CD28/CTLA-4-CD80/CD86 interactions were blocked using the fusion protein CTLA-4Ig. To examine the relative contribution of CD80- and CD86-mediated costimulation in these models, anti-CD80 and anti-CD86 blocking Abs were used. In the hypersensitivity model, CTLA-4Ig treatment prevented the development of peanut extract-induced cytokine responses, peanut extract-specific IgG1, IgG2a, and IgE production and peanut extract-induced challenge responses. Blocking of CD80 reduced, whereas anti-CD86 treatment completely inhibited, the induction of peanut extract-specific IgE. Normal tolerance induction to peanut extract was found following CTLA-4Ig, anti-CD86, or anti-CD80 plus anti-CD86 treatment, whereas blockade of CD80 impaired the induction of oral tolerance. We show that CD28/CTLA-4-CD80/CD86 signaling is essential for the development of allergic responses to peanut and that CD86 interaction is most important in inducing peanut extract-specific IgE responses. Additionally, our data suggest that CD80 but not CD86 interaction with CTLA-4 is crucial for the induction of low dose tolerance to peanut.
Functional Gap Junctions Facilitate Melanoma Antigen Transfer and Cross-Presentation between Human Dendritic Cells
Authors: Mendoza-Naranjo Ariadna , Saéz Pablo J. , Johansson C. Christian , Ramírez Marcos , Mandaković Dinka , Pereda Cristian , López Mercedes N. , Kiessling Rolf , Sáez Juan C. , Salazar-Onfray Flavio
Published: April 2014

Previously, we found that human dendritic cells (hDCs) pulsed with a melanoma cell lysate (MCL) and stimulated with TNF-α (MCL/TNF) acquire a mature phenotype in vitro and are able to trigger tumor-specific immune responses when they are used in melanoma immunotherapy in patients. In this study, we describe that MCL/TNF induces gap junction (GJ)-mediated intercellular communications and promotes melanoma Ag transfer between ex vivo produced hDCs from melanoma patients. hDCs also exhibit increased expression of the GJ-related protein connexin 43, which contributes to GJ plaque formation after MCL/TNF stimulation. The addition of GJ inhibitors suppresses intercellular tumor Ag transfer between hDCs, thus reducing melanoma-specific T cell activation. In summary, we demonstrate that MCL/TNF-stimulated hDCs can establish functional GJ channels that participate in melanoma Ag transfer, facilitating Ag cross-presentation and an effective dendritic cell-mediated melanoma-specific T cell response. These results suggest that GJs formed between hDCs used in cancer vaccination protocols could be essentials for the establishment of a more efficient antitumor response.
Parallel Loss of Myeloid and Plasmacytoid Dendritic Cells from Blood and Lymphoid Tissue in Simian AIDS
Authors: Brown Kevin N. , Trichel Anita , Barratt-Boyes Simon M.
Published: April 2014

The loss of myeloid (mDC) and plasmacytoid dendritic cells (pDC) from the blood of HIV-infected individuals is associated with progressive disease. It has been proposed that DC loss is due to increased recruitment to lymph nodes, although this has not been directly tested. Similarly as in HIV-infected humans, we found that lineage-negative (Lin−) HLA-DR+CD11c+CD123− mDC and Lin−HLA-DR+CD11c−CD123+ pDC were lost from the blood of SIV-infected rhesus macaques with AIDS. In the peripheral lymph nodes of SIV-naive monkeys the majority of mDC were mature cells derived from skin that expressed high levels of HLA-DR, CD83, costimulatory molecules, and the Langerhans cell marker CD1a, whereas pDC expressed low levels of HLA-DR and CD40 and lacked costimulatory molecules, similar to pDC in blood. Surprisingly, both DC subsets were depleted from peripheral and mesenteric lymph nodes and spleens in monkeys with AIDS, although the activation status of the remaining DC subsets was similar to that of DC in health. In peripheral and mesenteric lymph nodes from animals with AIDS there was an accumulation of Lin−HLA-DRmoderateCD11c−CD123− cells that resembled monocytoid cells but failed to acquire a DC phenotype upon culture, suggesting they were not DC precursors. mDC and pDC from the lymphoid tissues of monkeys with AIDS were prone to spontaneous death in culture, indicating that apoptosis may be a mechanism for their loss in disease. These findings demonstrate that DC are lost from rather than recruited to lymphoid tissue in advanced SIV infection, suggesting that systemic DC depletion plays a direct role in the pathophysiology of AIDS.
Role for CD21 in the Establishment of an Extracellular HIV Reservoir in Lymphoid Tissues
Authors: Ho Jason , Moir Susan , Kulik Liudmila , Malaspina Angela , Donoghue Eileen T. , Miller Natalie J. , Wang Wei , Chun Tae-Wook , Fauci Anthony S. , Holers V. Michael
Published: April 2014

Follicular dendritic cells (FDC) represent a major extracellular reservoir for HIV. A better understanding of the mechanisms of virion attachment to FDC may offer new avenues for reducing viral burdens in infected individuals. We used a murine model to investigate the establishment of extracellular HIV reservoirs in lymph nodes (LN). Consistent with findings in human tissues, CD21 was required for trapping of HIV to LN cells, as evidenced by significantly reduced virion binding when mice were pretreated with a C3 ligand-blocking anti-CD21 mAb and absence of virion trapping in CD21 knockout mice. Also consistent with findings in human tissues, the majority of HIV virions were associated with the FDC-enriched fraction of LN cell preparations. Somewhat surprisingly, HIV-specific Abs were not essential for HIV binding to LN cells, indicating that seeding of the FDC reservoir may begin shortly after infection and before the development of HIV-specific Abs. Finally, the virion-displacing potential for anti-CD21 mAbs was investigated. Treatment of mice with anti-CD21 mAbs several days after injection of HIV significantly reduced HIV bound to LN cells. Our findings demonstrate a critical role for CD21 in HIV trapping by LN cells and suggest a new therapeutic avenue for reducing HIV reservoirs.
Cytopiloyne, a Polyacetylenic Glucoside, Prevents Type 1 Diabetes in Nonobese Diabetic Mice
Authors: Chang Cicero Lee-Tian , Chang Shu-Lin , Lee Yi-Mei , Chiang Yi-Ming , Chuang Da-Yung , Kuo Hui-Kai , Yang Wen-Chin
Published: April 2014

Some polyacetylenes from the plant Bidens pilosa have been reported to treat diabetes. In this study, we report that the cytopiloyne from B. pilosa, which is structurally different from the above-mentioned polyacetylenes and inhibits CD4+ T cell proliferation, effectively prevents the development of diabetes in nonobese diabetic mice as evidenced by a normal level of blood glucose and insulin and normal pancreatic islet architecture. Cytopiloyne also suppresses the differentiation of type 1 Th cells but promotes that of type 2 Th cells, which is consistent with it enhancing GATA-3 transcription. Also, long-term application of cytopiloyne significantly decreases the level of CD4+ T cells inside pancreatic lymph nodes and spleens but does not compromise total Ab responses mediated by T cells. Coculture assays imply that this decrease in CD4+ T cells involves the Fas ligand/Fas pathway. Overall, our results suggest that cytopiloyne prevents type 1 diabetes mainly via T cell regulation.
In Vivo Signaling through the Neurokinin 1 Receptor Favors Transgene Expression by Langerhans Cells and Promotes the Generation of Th1- and Tc1-Biased Immune Responses
Authors: Mathers Alicia R. , Tckacheva Olga A. , Janelsins Brian M. , Shufesky William J. , Morelli Adrian E. , Larregina Adriana T.
Published: April 2014

The proinflammatory capacities of the skin and the presence of high numbers of resident dendritic cells (DCs) constitute an ideal microenvironment for successful immunizations. Regardless of the ability of DCs to respond to local inflammatory signals in an immunostimulatory fashion, the immune functions of skin-resident DCs remain controversial, and epidermal Langerhans cells (LCs) have been referred to recently as anti-inflammatory/protolerogenic APCs. Substance P (SP), released by skin nerve fibers, is a potent proinflammatory neuropeptide that favors development of skin-associated cellular immunity. SP exerts its proinflammatory functions by binding with high affinity to the neurokinin 1 receptor (NK1R). In this study, we tested whether signaling skin cells via the NK1R promotes humoral and cellular immunity during skin genetic immunizations. We used the gene gun to deliver transgenic (tg) Ag to the skin of C57BL/6 mice and the selective NK1R agonist [Sar9Met (O2) 11]-SP as a potential proinflammatory Th1-biasing adjuvant. Our strategy expressed tg Ag exclusively in the epidermis and induced a preferential migration of activated LCs to skin-draining lymph nodes. Local administration of the NK1R agonist during skin genetic immunizations increased significantly the expression of tg Ag by a mechanism involving the translocation of NF-κB into the nuclei of cutaneous DCs homing to skin-draining lymph nodes. Importantly, our immunization approach resulted in Th1 and T cytotoxic (CTL)-1 bias of effector T cells that supported cellular and Ab-mediated immune responses. We demonstrate that signaling skin cells via the NK1R provides the adjuvant effect which favors the immunostimulatory functions of LCs.
Rapamycin-Conditioned Dendritic Cells Are Poor Stimulators of Allogeneic CD4+ T Cells, but Enrich for Antigen-Specific Foxp3+ T Regulatory Cells and Promote Organ Transplant Tolerance
Authors: Turnquist Hēth R. , Raimondi Giorgio , Zahorchak Alan F. , Fischer Ryan T. , Wang Zhiliang , Thomson Angus W.
Published: April 2014

The ability of dendritic cells (DC) to regulate Ag-specific immune responses via their influence on T regulatory cells (Treg) may be key to their potential as therapeutic tools or targets for the promotion/restoration of tolerance. In this report, we describe the ability of maturation-resistant, rapamycin (RAPA)-conditioned DC, which are markedly impaired in Foxp3− T cell allostimulatory capacity, to favor the stimulation of murine alloantigen-specific CD4+CD25+Foxp3+ Treg. This was distinct from control DC, especially following CD40 ligation, which potently expanded non-Treg. RAPA-DC-stimulated Treg were superior alloantigen-specific suppressors of T effector responses compared with those stimulated by control DC. Supporting the ability of RAPA to target effector T and B cells, but permit the proliferation and suppressive function of Treg, an infusion of recipient-derived alloantigen-pulsed RAPA-DC followed by a short postoperative course of low-dose RAPA promoted indefinite (>100 day) heart graft survival. This was associated with graft infiltration by CD4+Foxp3+ Treg and the absence of transplant vasculopathy. The adoptive transfer of CD4+ T cells from animals with long-surviving grafts conferred resistance to rejection. These novel findings demonstrate that, whereas maturation resistance does not impair the capacity of RAPA-DC to modulate Treg, it profoundly impairs their ability to expand T effector cells. A demonstration of this mechanism endorses their potential as tolerance-promoting cellular vaccines.
Plasmodium berghei-Infected Primary Hepatocytes Process and Present the Circumsporozoite Protein to Specific CD8+ T Cells In Vitro
Authors: Bongfen Silayuv E. , Torgler Ralph , Romero Jackeline F. , Renia Laurent , Corradin Giampietro
Published: April 2014

A substantial and protective response against malaria liver stages is directed against the circumsporozoite protein (CSP) and involves induction of CD8+ T cells and production of IFN-γ. CSP-derived peptides have been shown to be presented on the surface of infected hepatocytes in the context of MHC class I molecules. However, little is known about how the CSP and other sporozoite Ags are processed and presented to CD8+ T cells. We investigated how primary hepatocytes from BALB/c mice process the CSP of Plasmodium berghei after live sporozoite infection and present CSP-derived peptides to specific H-2Kd-restricted CD8+ T cells in vitro. Using both wild-type and spect−/− P. berghei sporozoites, we show that both infected and traversed primary hepatocytes process and present the CSP. The processing and presentation pathway was found to involve the proteasome, Ag transport through a postendoplasmic reticulum compartment, and aspartic proteases. Thus, it can be hypothesized that infected hepatocytes can contribute in vivo to the elicitation and expansion of a T cell response.
Genome-Wide Analysis of Gene Expression in T Cells to Identify Targets of the NF-κB Transcription Factor c-Rel
Authors: Bunting Karen , Rao Sudha , Hardy Kristine , Woltring Donna , Denyer Gareth S. , Wang Jun , Gerondakis Steve , Shannon M. Frances
Published: April 2014

It is well established that the NF-κB family of transcription factors serves a major role in controlling gene expression in response to T cell activation, but the genome-wide roles of individual family members remain to be determined. c-Rel, a member of the NF-κB family, appears to play a specific role in T cell function because T cells from c-Rel−/− animals are defective in their response to immune signals. We have used expression profiling to identify sets of genes that are affected by either deletion or overexpression of c-Rel in T cells. Very few of these genes exhibit a strong requirement for c-Rel; rather, c-Rel appears to modulate the expression of a large number of genes in these cells. The sets of c-Rel-affected genes are significantly enriched for genes containing consensus NF-κB/Rel sites in their proximal promoter regions. In addition, their promoters contain a higher average density of NF-κB/Rel sites compared with all genes represented on the microarrays. A transcriptional module comprised of two closely spaced c-Rel consensus sites is found with higher frequency in the c-Rel-affected gene sets and may represent an important control module for genes regulated by c-Rel or other NF-κB family members. We confirmed the importance of these findings on a subgroup of genes by using quantitative PCR to monitor gene expression as well as in vitro c-Rel/DNA binding assays and luciferase reporter assays. The c-Rel-regulated genes identified here support a role for c-Rel in inflammatory responses as well as in the promotion of cell growth and survival.
The Autoimmune Regulator Directly Controls the Expression of Genes Critical for Thymic Epithelial Function
Authors: Ruan Qing-Guo , Tung Kenneth , Eisenman Daniel , Setiady Yulius , Eckenrode Sarah , Yi Bing , Purohit Sharad , Zheng Wei-Peng , Zhang Yan , Peltonen Leena , She Jin-Xiong
Published: April 2014

The autoimmune regulator (Aire) gene plays an essential role in negative selection of T cells and deletion of autoreactive T cells in the thymus. The defect in thymic selection in Aire−/− mice was attributed to the repressed expression of tissue-specific Ags in the thymic epithelial cells and defective Ag presentation; however, the molecular mechanism underlying these functions has been elusive. Using the chromatin immunoprecipitation technique, we demonstrate here that Aire binds in vivo to specific DNA sequence motifs and directly regulates thymic expression of genes important for thymic functions including expression of autoantigens, cytokines, transcription factors, and posttranslational modifiers. These results unambiguously established Aire as a key transcriptional regulator of the immune system.
Tubulation of Class II MHC Compartments Is Microtubule Dependent and Involves Multiple Endolysosomal Membrane Proteins in Primary Dendritic Cells
Authors: Vyas Jatin M. , Kim You-Me , Artavanis-Tsakonas Katerina , Love J. Christopher , Van der Veen Annemarthe G. , Ploegh Hidde L.
Published: April 2014

Immature dendritic cells (DCs) capture exogenous Ags in the periphery for eventual processing in endolysosomes. Upon maturation by TLR agonists, DCs deliver peptide-loaded class II MHC molecules from these compartments to the cell surface via long tubular structures (endolysosomal tubules). The nature and rules that govern the movement of these DC compartments are unknown. In this study, we demonstrate that the tubules contain multiple proteins including the class II MHC molecules and LAMP1, a lysosomal resident protein, as well as CD63 and CD82, members of the tetraspanin family. Endolysosomal tubules can be stained with acidotropic dyes, indicating that they are extensions of lysosomes. However, the proper trafficking of class II MHC molecules themselves is not necessary for endolysosomal tubule formation. DCs lacking MyD88 can also form endolysosomal tubules, demonstrating that MyD88-dependent TLR activation is not necessary for the formation of this compartment. Endolysosomal tubules in DCs exhibit dynamic and saltatory movement, including bidirectional travel. Measured velocities are consistent with motor-based movement along microtubules. Indeed, nocodazole causes the collapse of endolysosomal tubules. In addition to its association with microtubules, endolysosomal tubules follow the plus ends of microtubules as visualized in primary DCs expressing end binding protein 1 (EB1)-enhanced GFP.
B Cells Moderate Inflammatory Progression and Enhance Bacterial Containment upon Pulmonary Challenge withMycobacterium tuberculosis
Authors: Maglione Paul J. , Xu Jiayong , Chan John
Published: April 2014

Though much is known about the function of T lymphocytes in the adaptive immune response against Mycobacterium tuberculosis, comparably little is understood regarding the corresponding role of B lymphocytes. Indicating B cells as components of lymphoid neogenesis during pulmonary tuberculosis, we have identified ectopic germinal centers (GCs) in the lungs of infected mice. B cells in these pulmonary lymphoid aggregates express peanut agglutinin and GL7, two markers of GC B cells, as well as CXCR5, and migrate in response to the lymphoid-associated chemokine CXCL13 ex vivo. CXCL13 is negatively regulated by the presence of B cells, as its production is elevated in lungs of B cell-deficient (B cell−/−) mice. Upon aerosol with 100 CFU of M. tuberculosis Erdman, B cell−/− mice have exacerbated immunopathology corresponding with elevated pulmonary recruitment of neutrophils. Infected B cell−/− mice show increased production of IL-10 in the lungs, whereas IFN-γ, TNF-α, and IL-10R remain unchanged from wild type. B cell−/− mice have enhanced susceptibility to infection when aerogenically challenged with 300 CFU of M. tuberculosis corresponding with elevated bacterial burden in the lungs but not in the spleen or liver. Adoptive transfer of B cells complements the phenotypes of B cell−/− mice, confirming a role for B cells in both modulation of the host response and optimal containment of the tubercle bacillus. As components of ectopic GCs, moderators of inflammatory progression, and enhancers of local immunity against bacterial challenge, B cells may have a greater role in the host defense against M. tuberculosis than previously thought.
Biphasic Effect of Gingipains from Porphyromonas gingivalis on the Human Complement System
Authors: Popadiak Katarzyna , Potempa Jan , Riesbeck Kristian , Blom Anna M.
Published: April 2014

Periodontitis is an inflammatory disease of the supporting structures of the teeth and is caused by, among other agents, Porphyromonas gingivalis. P. gingivalis is very resistant to killing by human complement, which is present in a gingival fluid at 70% of the serum concentration. We found that the incubation of human serum with purified cysteine proteases of P. gingivalis (gingipains) or P. gingivalis wild-type strains W83 and W50 resulted in a drastic decrease of the bactericidal activity of the serum. In contrast, serum treated with P. gingivalis mutants lacking gingipains (particularly strains without HRgpA) maintained significant bactericidal activity. To understand in detail the mechanism by which gingipains destroy the serum bactericidal activity, we investigated the effects of gingipains on the human complement system. We found that all three proteases degraded multiple complement components, with arginine-specific gingipains (HRgpA and RgpB) being more efficient than lysine-specific gingipain (Kgp). Interestingly, all three proteases at certain concentrations were able to activate the C1 complex in serum, which resulted in the deposition of C1q on inert surfaces and on bacteria themselves. It is therefore plausible that P. gingivalis activates complement when present at low numbers, resulting in a local inflammatory reaction and providing the bacteria with a colonization opportunity and nutrients. At later stages of infection the concentration of proteases is high enough to destroy complement factors and thus render the bacteria resistant to the bactericidal activity of complement.
Dendritic Cell-Derived IL-12p40 Homodimer Contributes to Susceptibility in Cutaneous Leishmaniasis in BALB/c Mice
Authors: Nigg Axel P. , Zahn Sabine , Rückerl Dominik , Hölscher Christoph , Yoshimoto Takayuki , Ehrchen Jan M. , Wölbing Florian , Udey Mark C. , von Stebut Esther
Published: April 2014

Protection against Leishmania major in resistant C57BL/6 mice is mediated by Th1 cells, whereas susceptibility in BALB/c mice is the result of Th2 development. IL-12 release by L. major-infected dendritic cells (DC) is critically involved in differentiation of Th1 cells. Previously, we reported that strain differences in the production of DC-derived factors, e.g., IL-1αβ, are in part responsible for disparate disease outcome. In the present study, we analyzed the release of IL-12 from DC in more detail. Stimulated DC from C57BL/6 and BALB/c mice released comparable amounts of IL-12p40 and p70. In the absence of IL-4, BALB/c DC produced significantly more IL-12p40 than C57BL/6 DC. Detailed analyses by Western blot and ELISA revealed that one-tenth of IL-12p40 detected in DC supernatants was released as the IL-12 antagonist IL-12p40 homodimer (IL-12p80). BALB/c DC released ∼2-fold more IL-12p80 than C57BL/6 DC both in vitro and in vivo. Local injection of IL-12p80 during the first 3 days after infection resulted in increased lesion volumes for several weeks in both L. major-infected BALB/c or C57BL/6 mice, in higher lesional parasite burdens, and decreased Th1-cytokine production. Finally, IL-12p40-transgenic C57BL/6 mice characterized by overexpression of p40 showed increased levels of serum IL-12p80 and enhanced disease susceptibility. Thus, in addition to IL-1αβ, strain-dependent differences in the release of other DC-derived factors such as IL-12p80 may influence genetically determined disease outcome.
C-Reactive Protein Enhances Immunity to Streptococcus pneumoniae by Targeting Uptake to FcγR on Dendritic Cells
Authors: Thomas-Rudolph Deirdre , Du Clos Terry W. , Snapper Clifford M. , Mold Carolyn
Published: April 2014

C-reactive protein (CRP) is an acute phase reactant with roles in innate host defense, clearance of damaged cells, and regulation of the inflammatory response. These activities of CRP depend on ligand recognition, complement activation, and binding to FcγR. CRP binds to phosphocholine in the Streptococcus pneumoniae cell wall and provides innate defense against pneumococcal infection. These studies examine the effect of this early innate defense molecule on the development of Abs and protective immunity to S. pneumoniae. Dendritic cells (DC) initiate and direct the adaptive immune response by integrating innate stimuli with cytokine synthesis and Ag presentation. We hypothesized that CRP would direct uptake of S. pneumoniae to FcγR on DC and enhance Ag presentation. CRP opsonization of the R36a strain of S. pneumoniae increased the uptake of bacteria by DC. DC pulsed with untreated or CRP-opsonized R36a were transferred into recipient mice, and Ab responses were measured. In mice challenged with free R36a, CRP opsonization resulted in higher secondary and memory IgG responses to both phosphocholine and pneumococcal surface protein A. Furthermore, mice immunized with DC that had been pulsed with CRP-opsonized R36a showed increased resistance to intranasal infection with virulent S. pneumoniae. The effects of CRP on Ag uptake, Ab responses, and protection from infection all required FcR γ-chain expression on DC. The results indicate that innate recognition by CRP enhances effective uptake and presentation of bacterial Ags through FcγR on DC and stimulates protective adaptive immunity.
A Novel RBP-Jκ-Dependent Switch from C/EBPβ to C/EBPζ at the C/EBP Binding Site on the C-Reactive Protein Promoter
Authors: Singh Prem Prakash , Voleti Bhavya , Agrawal Alok
Published: April 2014

Regulation of basal and cytokine (IL-6 and IL-1β)-induced expression of C-reactive protein (CRP) in human hepatoma Hep3B cells occurs during transcription. A critical transcriptional regulatory element on the CRP promoter is a C/EBP binding site overlapping a NF-κB p50 binding site. In response to IL-6, C/EBPβ and p50 occupy the C/EBP-p50 site on the CRP promoter. The aim of this study was to identify the transcription factors occupying the C/EBP-p50 site in the absence of C/EBPβ. Accordingly, we treated Hep3B nuclear extract with a C/EBP-binding consensus oligonucleotide to generate an extract lacking active C/EBPβ. Such treated nuclei contain only C/EBPζ (also known as CHOP10 and GADD153) because the C/EBP-binding consensus oligonucleotide binds to all C/EBP family proteins except C/EBPζ. EMSA using this extract revealed formation of a C/EBPζ-containing complex at the C/EBP-p50 site on the CRP promoter. This complex also contained RBP-Jκ, a transcription factor known to interact with κB sites. RBP-Jκ was required for the formation of C/EBPζ-containing complex. The RBP-Jκ-dependent C/EBPζ-containing complexes were formed at the C/EBP-p50 site on the CRP promoter in the nuclei of primary human hepatocytes also. In luciferase transactivation assays, overexpressed C/EBPζ abolished both C/EBPβ-induced and (IL-6 + IL-1β)-induced CRP promoter-driven luciferase expression. These results indicate that under basal conditions, C/EBPζ occupies the C/EBP site, an action that requires RBP-Jκ. Under induced conditions, C/EBPζ is replaced by C/EBPβ and p50. We conclude that the switch between C/EBPβ and C/EBPζ participates in regulating CRP transcription. This process uses a novel phenomenon, that is, the incorporation of RBP-Jκ into C/EBPζ complexes solely to support the binding of C/EBPζ to the C/EBP site.
A Peroxynitrite-Dependent Pathway Is Responsible for Blood-Brain Barrier Permeability Changes during a Central Nervous System Inflammatory Response: TNF-α Is Neither Necessary nor Sufficient
Authors: Phares Timothy W. , Fabis Marzena J. , Brimer Christine M. , Kean Rhonda B. , Hooper D. Craig
Published: April 2014

Elevated blood-brain barrier (BBB) permeability is associated with both the protective and pathological invasion of immune and inflammatory cells into CNS tissues. Although a variety of processes have been implicated in the changes at the BBB that result in the loss of integrity, there has been no consensus as to their induction. TNF-α has often been proposed to be responsible for increased BBB permeability but there is accumulating evidence that peroxynitrite (ONOO−)-dependent radicals may be the direct trigger. We demonstrate here that enhanced BBB permeability in mice, whether associated with rabies virus (RV) clearance or CNS autoimmunity, is unaltered in the absence of TNF-α. Moreover, the induction of TNF-α expression in CNS tissues by RV infection has no impact on BBB integrity in the absence of T cells. CD4 T cells are required to enhance BBB permeability in response to the CNS infection whereas CD8 T cells and B cells are not. Like CNS autoimmunity, elevated BBB permeability in response to RV infection is evidently mediated by ONOO−. However, as opposed to the invading cells producing ONOO− that have been implicated in the pathogenesis of CNS inflammation, during virus clearance ONOO− is produced without pathological sequelae by IFN-γ-stimulated neurovascular endothelial cells.
Proinflammatory Proteases Liberate a Discrete High-Affinity Functional FPRL1 (CCR12) Ligand from CCL23
Authors: Miao Zhenhua , Premack Brett A. , Wei Zheng , Wang Yu , Gerard Craig , Showell Henry , Howard Maureen , Schall Thomas J. , Berahovich Robert
Published: April 2014

Most chemokines have been found to bind to and signal through single or highly related chemokine receptors. However, a single chemokine protein, a processed form of the alternatively spliced CCL23 (CKβ8/MPIF-1) gene product, potently engages both the “classical” chemokine receptor CCR1, as well as FPRL1, a type of pattern recognition receptor on innate immune cells. However, the mechanism by which the alternative form of CCL23 is processed is unknown. In this study, we show that proteases associated with inflammation cleave CCL23 immediately N-terminal to the 18-residue domain encoded by the alternatively spliced nucleotides, resulting in potent CCR1 and FPRL1 activity. The proteases also cleave CCL23 immediately C-terminal to the inserted domain, producing a typical CC chemokine “body” containing even further-increased CCR1 potency and a released ∼18-aa peptide with full FPRL1 activity but no activity for CCR1. This peptide, which we term SHAAGtide, is by itself an attractant of monocytes and neutrophils in vitro, recruits leukocytes in vivo, and is 50- to 100-fold more potent than all other natural agents posited to act on FPRL1. The appearance of SHAAGtide appears to be transient, however, as the proinflammatory proteases subsequently cleave within the peptide, abolishing its activity for FPRL1. The sequential activation of a transient FPRL1 ligand and a longer-lived CCR1 ligand within a single chemokine may have important consequences for the development of inflammation or the link between innate and adaptive immunity.
Tubulin Is a Neuronal Target of Autoantibodies in Sydenham’s Chorea
Authors: Kirvan Christine A. , Cox Carol J. , Swedo Susan E. , Cunningham Madeleine W.
Published: April 2014

Sydenham’s chorea is a CNS disorder and sequela of group A streptococcal infection where deposition of Abs in brain may result in movement and neuropsychiatric abnormalities. We studied human mAbs 24.3.1, 31.1.1, and 37.2.1 derived from chorea and selected for cross-reactivity with group A streptococci and brain Ags. Our novel findings reveal that Sydenham’s chorea mAbs target a 55-kDa brain protein with an N-terminal amino acid sequence of MREIVHLQ corresponding to β-tubulin. Chorea mAb specificity for purified brain tubulin was confirmed in ELISA and Western immunoblot, and significant levels of anti-tubulin IgG were found in acute chorea sera and cerebrospinal fluid. Lysoganglioside GM1 inhibited binding of chorea mAbs to tubulin and mAb reactivity with human caudate and putamen brain sections was blocked by anti-tubulin mAb. The chorea mAbs labeled both intra- and extracellular Ags of a neuronal cell line providing evidence suggesting mimicry between intracellular brain protein tubulin and extracellular lysoganglioside. In addition, chorea mAb 24.3.1 and acute chorea sera induced calcium/calmodulin-dependent protein kinase II activity in human neuronal cells. Nucleotide sequence analysis of the chorea mAb VH genes revealed that mAb 24.3.1 VH gene was encoded by the VH1 germline gene family which encodes other anti-ganglioside VH genes associated with motor neuropathies. mAb recognition of tubulin and the neuronal cell surface with initiation of cell signaling and dopamine release supports an emerging theme in autoimmunity whereby cross-reactive or polyreactive autoantibodies against intracellular Ags recognize cell surface epitopes potentially leading to disease.
Abrogation of Lupus Nephritis in Activation-Induced Deaminase-Deficient MRL/lpr Mice
Authors: Jiang Chuancang , Foley Julie , Clayton Natasha , Kissling Grace , Jokinen Micheal , Herbert Ronald , Diaz Marilyn
Published: April 2014

We generated MRL/lpr mice deficient in activation-induced deaminase (AID). Because AID is required for Ig hypermutation and class switch recombination, these mice lack hypermutated IgG Abs. Unlike their AID wild-type littermates, AID-deficient MRL/lpr mice not only lacked autoreactive IgG Abs but also experienced a dramatic increase in the levels of autoreactive IgM. This phenotype in AID-deficient mice translated into a significant reduction in glomerulonephritis, minimal mononuclear cell infiltration in the kidney, and a dramatic increase in survival to levels comparable to those previously reported for MRL/lpr mice completely lacking B cells and well below those of mice lacking secreted Abs. Therefore, this study wherein littermates with either high levels of autoreactive IgM or autoreactive IgG were directly examined proves that autoreactive IgM Abs alone are not sufficient to promote kidney disease in MRL/lpr mice. In addition, the substantial decrease in mortality combined with a dramatic increase in autoreactive IgM Abs in AID-deficient MRL/lpr mice suggest that autoreactive IgM Abs might not only fail to promote nephritis but may also provide a protective role in MRL/lpr mice. This novel mouse model containing high levels of autoreactive, unmutated IgM Abs will help delineate the contribution of autoreactive IgM to autoimmunity.
Immunization of HLA Class I Transgenic Mice Identifies Autoantigenic Epitopes Eliciting Dominant Responses in Type 1 Diabetes Patients
Authors: Blancou Philippe , Mallone Roberto , Martinuzzi Emanuela , Sévère Sabine , Pogu Sylvie , Novelli Giulia , Bruno Graziella , Charbonnel Bernard , Dolz Manuel , Chaillous Lucy , van Endert Peter , Bach Jean-Marie
Published: April 2014

Type 1 diabetes (T1D) results from the autoimmune destruction of pancreatic β cells. CD8+ T cells have recently been assigned a major role in β cell injury. Consequently, the identification of autoreactive CD8+ T cells in humans remains essential for development of therapeutic strategies and of assays to identify aggressive cells. However, this identification is laborious and limited by quantities of human blood samples available. We propose a rapid and reliable method to identify autoantigen-derived epitopes recognized by human CD8+ T lymphocytes in T1D patients. Human histocompatibility leukocyte Ags-A*0201 (HLA-A*0201) transgenic mice were immunized with plasmids encoding the T1D-associated autoantigens: 65 kDa glutamic acid decarboxylase (GAD) or insulinoma-associated protein 2 (IA-2). Candidate epitopes for T1D were selected from peptide libraries by testing the CD8+ reactivity of vaccinated mice. All of the nine-candidate epitopes (five for GAD and four for IA-2) identified by our experimental approach were specifically recognized by CD8+ T cells from newly diagnosed T1D patients (n = 19) but not from CD8+ T cells of healthy controls (n = 20). Among these, GAD114–123, GAD536–545 and IA-2805–813 were recognized by 53%, 25%, and 42% of T1D patients, respectively.
Comparing ELISA and Surface Plasmon Resonance for Assessing Clinical Immunogenicity of Panitumumab
Authors: Lofgren James A. , Dhandapani Sripriya , Pennucci Jason J. , Abbott Christina M. , Mytych Daniel T. , Kaliyaperumal Arunan , Swanson Steven J. , Mullenix Michael C.
Published: April 2014

Evaluation of the immunogenicity of panitumumab, a fully human anti-epidermal growth factor receptor mAb approved for use in colorectal cancer patients, led to the development of two separate immunoassays for the detection of anti-panitumumab Abs. The first immunoassay used a bridging ELISA capable of detecting 10 ng/ml positive control anti-panitumumab Ab. The ELISA incorporated an acid dissociation step to reduce drug interference and tolerated the presence of ∼100-fold molar excess of drug. During eight clinical trials, the ELISA detected developing Ab responses in 2 of 612 (0.3%) subjects. In one of the ELISA positive subjects, neutralizing Abs were detected using an epidermal growth factor receptor phosphorylation bioassay. The second immunoassay used a Biacore biosensor immunoassay format capable of detecting 1 μg/ml positive control Ab while tolerating the presence of equal molar amounts of drug. Although less sensitive and less tolerant to competing drug in the assay, the Biacore assay detected developing Ab responses in 25 of the 604 (4.1%) subjects. Additionally, the Biacore assay identified eight subjects who developed neutralizing Abs. Mouse mAbs with affinities ranging from 1.1 × 10−6 to 8.4 × 10−10 M were used to characterize both assay types. The ELISA was more sensitive for the detection of higher affinity mAbs and detected high-affinity mAbs in the presence of higher molar ratio of drug to mAb. The Biacore assay was more sensitive for detection of lower affinity mAbs and detected low affinity Abs in the presence of higher molar ratios of drug to mAb.
Enhanced Immune Reconstitution by Sex Steroid Ablation following Allogeneic Hemopoietic Stem Cell Transplantation
Authors: Goldberg Gabrielle L. , Alpdogan Önder , Muriglan Stephanie J. , Hammett Maree V. , Milton Morag K. , Eng Jeffrey M. , Hubbard Vanessa M. , Kochman Adam , Willis Lucy M. , Greenberg Andrew S. , Tjoe Kartono H. , Sutherland Jayne S. , Chidgey Ann , van den Brink Marcel R. M. , Boyd Richard L.
Published: April 2014

Delayed immune reconstitution in adult recipients of allogeneic hemopoietic stem cell transplantations (HSCT) is related to age-induced thymic atrophy. Overcoming this paucity of T cell function is a major goal of clinical research but in the context of allogeneic transplants, any strategy must not exacerbate graft-vs-host disease (GVHD) yet ideally retain graft-vs-tumor (GVT) effects. We have shown sex steroid ablation reverses thymic atrophy and enhances T cell recovery in aged animals and in congenic bone marrow (BM) transplant but the latter does not have the complications of allogeneic T cell reactivity. We have examined whether sex steroid ablation promoted hemopoietic and T cell recovery following allogeneic HSCT and whether this benefit was negated by enhanced GVHD. BM and thymic cell numbers were significantly increased at 14 and 28 days after HSCT in castrated mice compared with sham-castrated controls. In the thymus, the numbers of donor-derived thymocytes and dendritic cells were significantly increased after HSCT and castration; donor-derived BM precursors and developing B cells were also significantly increased. Importantly, despite restoring T cell function, sex steroid inhibition did not exacerbate the development of GVHD or ameliorate GVT activity. Finally, IL-7 treatment in combination with castration had an additive effect on thymic cellularity following HSCT. These results indicate that sex steroid ablation can profoundly enhance thymic and hemopoietic recovery following allogeneic HSCT without increasing GVHD and maintaining GVT.