bluuebunny/crossref_metadata_2025 huggingface dataset:
A Critical Role for Type I IFN in Arthritis Development followingBorrelia burgdorferiInfection of Mice
Authors: Miller Jennifer C. , Ma Ying , Bian Jiantao , Sheehan Kathleen C. F. , Zachary James F. , Weis John H. , Schreiber Robert D. , Weis Janis J.
Published: April 2014

Gene expression analysis previously revealed a robust IFN-responsive gene induction profile that was selectively up-regulated in Borrelia burgdorferi-infected C3H mice at 1 wk postinfection. This profile was correlated with arthritis development, as it was absent from infected, mildly arthritic C57BL/6 mice. In this report we now demonstrate that profile induction in infected C3H scid mice occurs independently of B or T lymphocyte infiltration in the joint tissue. Additionally, type I IFN receptor-blocking Abs, but not anti-IFN-γ Abs, dramatically reduced arthritis, revealing a critical but previously unappreciated role for type I IFN in Lyme arthritis development. Certain examined IFN-inducible transcripts were also significantly diminished within joint tissue of mice treated with anti-IFNAR1, whereas expression of other IFN-responsive genes was more markedly altered by anti-IFN-γ treatment. These data indicate that induction of the entire IFN profile is not necessary for arthritis development. These findings further tie early type I IFN induction to Lyme arthritis development, a connection not previously made. Bone marrow-derived macrophages readily induced IFN-responsive genes following B. burgdorferi stimulation, and this expression required a functional type I IFN receptor. Strikingly, induction of these genes was independent of TLRs 2,4, and 9 and of the adapter molecule MyD88. These data demonstrate that the extracellular pathogen B. burgdorferi uses a previously unidentified receptor and a pathway traditionally associated with viruses and intracellular bacteria to initiate transcription of type I IFN and IFN-responsive genes and to initiate arthritis development.
Dendritic Cell IL-23 and IL-1 Production in Response to Schistosome Eggs Induces Th17 Cells in a Mouse Strain Prone to Severe Immunopathology
Authors: Shainheit Mara G. , Smith Patrick M. , Bazzone Lindsey E. , Wang Andrew C. , Rutitzky Laura I. , Stadecker Miguel J.
Published: April 2014

Infection with schistosomes results in a CD4 T cell-mediated inflammatory reaction against parasite eggs that varies greatly in magnitude both in humans as well as in mice. In the murine disease, the severe form of immunopathology correlates with high levels of IL-17. We now report that live schistosome eggs stimulate dendritic cells from high pathology-prone CBA mice to produce IL-12p40, IL-6, and TGF-β, whereas those from low pathology-prone BL/6 mice only make TGF-β. Moreover, egg-stimulated dendritic cells plus naive CD4 T cells from CBA mice resulted in increased levels of IL-6, IL-23, IL-1β, as well as IL-17 and the chemokines CXCL1, CXCL2, and CCL2, whereas similarly treated BL/6 cell cocultures instead expressed higher IL-4, IL-5, IL-10, and the transcription factor Foxp3. Neutralization of IL-23 and IL-1, but not of IL-6 or IL-21, profoundly inhibited egg-induced IL-17 production in the CBA cocultures. Conversely, stimulation with schistosome eggs in the presence of exogenous IL-23 and IL-1β induced BL/6 cells to make IL-17. These findings identify IL-23 and IL-1 as critical host factors that drive IL-17 production, and suggest that parasite recognition followed by a genetically determined innate proinflammatory response induces the development of Th17 cells and thus controls the outcome of immunopathology in schistosomiasis.
Activation of the Acquired Immune Response Reduces Coupled Bone Formation in Response to a Periodontal Pathogen
Authors: Behl Yugal , Siqueira Michelle , Ortiz Javier , Li Jingchao , Desta Tesfahun , Faibish Dan , Graves Dana T.
Published: April 2014

Osteoimmunolgy involves the interaction of the immune system with skeletal elements. This interaction can lead to the formation of osseous lesions. To investigate how the acquired immune response could contribute to osteolytic lesions, we injected the periodontal pathogen Porphyromonas gingivalis adjacent to calvarial bone with or without prior immunization against the bacterium. Activation of the acquired immune response increased osteoclastogenesis and decreased coupled bone formation. The latter was accompanied by an increase in nuclear translocation of the transcription factor FOXO1 in vivo, increased apoptosis of bone-lining cells measured by the TUNEL assay and number of activated caspase-3 positive cells and a decrease in bone lining cell density. Further studies were conducted with MC3T3 osteoblastic cells. Apoptosis and increased FOXO1 DNA binding activity were induced when a combination of cytokines was tested, IL-β, TNF-α, and IFN-γ. Knockdown of FOXO1 by small interfering RNA significantly reduced cytokine stimulated apoptosis, cleaved caspase-3/7 activity and decreased mRNA levels of the proapoptotic genes, TNF-α, FADD, and caspase-3, -8, and -9. These results indicate that activation of the acquired immunity by a periodontal pathogen reduces the coupling of bone formation and resorption. This may occur by enhancing bone lining cell apoptosis through a mechanism that involves increased FOXO1 activation. These studies give insight into inflammatory bone diseases such as periodontal disease and arthritis were the formation of lytic lesions occurs in conjunction with deficient bone formation and activation of an acquired immune response.
The Complement Factor C5a Contributes to Pathology in a Rat Model of Amyotrophic Lateral Sclerosis
Authors: Woodruff Trent M. , Costantini Kerina J. , Crane James W. , Atkin Julie D. , Monk Peter N. , Taylor Stephen M. , Noakes Peter G.
Published: April 2014

Complement activation products are elevated in the cerebrospinal fluid and spinal cord of patients with amyotrophic lateral sclerosis (ALS). In this study, we demonstrate complement system involvement in a rodent model of ALS (human SOD1G93A transgenic rats). With end-stage disease, SOD1G93A rats displayed marked deposition of C3/C3b, and a significant up-regulation of the C5aR in the lumbar spinal cord. This was associated with increased numbers of C5aR-positive astrocytes. However, expression of C5L2, the alternative receptor for C5a, was highest on motor neurons early in the disease process. To determine the contribution of C5a to the pathology displayed by this model of ALS, rats were administered an orally active, selective C5aR antagonist (PMX205; 1 mg/kg/day, oral). Animals treated with PMX205 displayed a significant extension of survival time and a reduction in end-stage motor scores, as compared with vehicle-treated rats. PMX205-treated animals also displayed reduced levels of astroglial proliferation in the lumbar spinal cord. This study provides the first demonstration of an involvement of C5a in an ALS model and suggests that inhibitors of complement activation could be beneficial in the treatment of this neurodegenerative disease.
Outgrowth of CD4low/negCD25+ T Cells with Suppressor Function in CD4+CD25+ T Cell Cultures upon Polyclonal Stimulation Ex Vivo
Authors: Vogtenhuber Christine , O'Shaughnessy Matthew J. , Vignali Dario A. A. , Blazar Bruce R.
Published: April 2014

CD4+CD25+ regulatory T cells (Tregs) play an essential role in controlling autoimmunity and allograft rejection. Several ex vivo activation and expansion protocols have been developed to amplify cell numbers and suppressor function of murine and human Tregs. We demonstrate in this study that ex vivo activation and expansion of murine Tregs resulted in an enrichment of a CD4low/negCD25+ T cell population that was more than 20-fold more potent than expanded conventional Tregs in suppressing an in vitro CD4+CD25− T cell response to allo-Ag. The generation of CD4low/negCD25+ T cells was independent of the presence of Tregs in the culture, and suppressor function was acquired only after activation and expansion. CD4low/negCD25+ T cells expressed either an αβ or γδ TCR, had an activated phenotype, and did not express the transcription factor FoxP3. Despite expressing the cell surface Ags lymphocyte activation gene-3 (CD223) and CD103, neither was essential for suppressor cell function. Suppression by CD4low/negCD25+ T cells was prevented by a semipermeable membrane and was independent of IL-10 and TGF-β. In summary, we describe in this study CD4low/negCD25+ FoxP3neg T cells with highly potent suppressor cell function derived from cultures of an enriched population of CD4+CD25+ T cells that may contribute to the suppressor activity of ex vivo expanded bone fide Tregs.
Contribution of Regulatory T Cells and Effector T Cell Deletion in Tolerance Induction by Costimulation Blockadel
Authors: Verbinnen Bert , Billiau An D. , Vermeiren Jan , Galicia Georgina , Bullens Dominique M. A. , Boon Louis , Cadot Pascal , Hens Greet , Dewolf-Peeters Christiane , Van Gool Stefaan W. , Ceuppens Jan L.
Published: April 2014

Blocking of costimulatory signals for T cell activation leads to tolerance in several transplantation models, but the underlying mechanisms are incompletely understood. We analyzed the involvement of regulatory T cells (Treg) and deletion of alloreactive cells in the induction and maintenance of tolerance after costimulation blockade in a mouse model of graft-vs-host reaction. Injection of splenocytes from the C57BL/6 parent strain into a sublethally irradiated F1 offspring (C57BL/6 × C3H) induced a GVHR characterized by severe pancytopenia. Treatment with anti-CD40L mAb and CTLA4-Ig every 3 days during 3 wk after splenocyte injection prevented disease development and induced a long-lasting state of stable mixed chimerism (>120 days). In parallel, host-specific tolerance was achieved as demonstrated by lack of host-directed alloreactivity of donor-type T cells in vitro and in vivo. Chimerism and tolerance were also obtained after CD25+ cell-depleted splenocyte transfer, showing that CD25+ natural Treg are not essential for tolerance induction. We further show that costimulation blockade results in enhanced Treg cell activity at early time points (days 6–30) after splenocyte transfer. This was demonstrated by the presence of a high percentage of Foxp3+ cells among donor CD4+ cells in the spleen of treated animals, and our finding that isolated donor-type T cells at an early time point (day 30) after splenocyte transfer displayed suppressive capacity in vitro. At later time points (>30 days after splenocyte transfer), clonal deletion of host-reactive T cells was found to be a major mechanism responsible for tolerance.
Recruitment and Endo-Lysosomal Activation of TLR9 in Dendritic Cells Infected withTrypanosoma cruzi
Authors: Bartholomeu Daniella C. , Ropert Catherine , Melo Mariane B. , Parroche Peggy , Junqueira Caroline F. , Teixeira Santuza M. R. , Sirois Cherilyn , Kasperkovitz Pia , Knetter Cathrine F. , Lien Egil , Latz Eicke , Golenbock Douglas T. , Gazzinelli Ricardo T.
Published: April 2014

TLR9 is critical in parasite recognition and host resistance to experimental infection with Trypanosoma cruzi. However, no information is available regarding nucleotide sequences and cellular events involved on T. cruzi recognition by TLR9. In silico wide analysis associated with in vitro screening of synthetic oligonucleotides demonstrates that the retrotransposon VIPER elements and mucin-like glycoprotein (TcMUC) genes in the T. cruzi genome are highly enriched for CpG motifs that are immunostimulatory for mouse and human TLR9, respectively. Importantly, infection with T. cruzi triggers high levels of luciferase activity under NF-κB-dependent transcription in HEK cells cotransfected with human TLR9, but not in control (cotransfected with human MD2/TLR4) HEK cells. Further, we observed translocation of TLR9 to the lysosomes during invasion/uptake of T. cruzi parasites by dendritic cells. Consistently, potent proinflammatory activity was observed when highly unmethylated T. cruzi genomic DNA was delivered to the endo-lysosomal compartment of host cells expressing TLR9. Thus, together our results indicate that the unmethylated CpG motifs found in the T. cruzi genome are likely to be main parasite targets and probably become available to TLR9 when parasites are destroyed in the lysosome-fused vacuoles during parasite invasion/uptake by phagocytes.
Chemotactic Activity of S100A7 (Psoriasin) Is Mediated by the Receptor for Advanced Glycation End Products and Potentiates Inflammation with Highly Homologous but Functionally Distinct S100A15
Authors: Wolf Ronald , Howard O. M. Zack , Dong Hui-Fang , Voscopoulos Christopher , Boeshans Karen , Winston Jason , Divi Rao , Gunsior Michele , Goldsmith Paul , Ahvazi Bijan , Chavakis Triantafyllos , Oppenheim Joost J. , Yuspa Stuart H.
Published: April 2014

Human S100A7 (psoriasin) is overexpressed in inflammatory diseases. The recently discovered, co-evolved hS100A15 is almost identical in sequence and up-regulated with hS100A7 during cutaneous inflammation. The functional role of these closely related proteins for inflammation remains undefined. By generating specific Abs, we demonstrate that hS100A7 and hS100A15 proteins are differentially expressed by specific cell types in the skin. Although highly homologous, both proteins are chemoattractants with distinct chemotactic activity for leukocyte subsets. We define RAGE (receptor for advanced glycation end products) as the hS100A7 receptor, whereas hS100A15 functions through a Gi protein-coupled receptor. hS100A7-RAGE binding, signaling, and chemotaxis are zinc-dependent in vitro, reflecting the previously reported zinc-mediated changes in the hS100A7 dimer structure. When combined, hS100A7 and hS100A15 potentiate inflammation in vivo. Thus, proinflammatory synergism in disease may be driven by the diverse biology of these almost identical proteins that have just recently evolved. The identified S100A7 interaction with RAGE may provide a novel therapeutic target for inflammation.
The Memory T Cell Response to West Nile Virus in Symptomatic Humans following Natural Infection Is Not Influenced by Age and Is Dominated by a Restricted Set of CD8+ T Cell Epitopes
Authors: Parsons Robin , Lelic Alina , Hayes Lisa , Carter Alexandra , Marshall Laura , Evelegh Carole , Drebot Michael , Andonova Maya , McMurtrey Curtis , Hildebrand William , Loeb Mark B. , Bramson Jonathan L.
Published: April 2014

We examined the West Nile virus (WNV)-specific T cell response in a cohort of 52 patients with symptomatic WNV infections, including neuroinvasive and non-invasive disease. Although all virus proteins were shown to contain T cell epitopes, certain proteins, such as E, were more commonly targeted by the T cell response. Most patients exhibited reactivity toward 3–4 individual WNV peptides; however, several patients exhibited reactivity toward >10 individual peptides. The relative hierarchy of T cell reactivities in all patients showed a fixed pattern that was sustained throughout the 12-mo period of the current study. Surprisingly, we did not observe any relationship between age and either the breadth or magnitude of the T cell response following infection. We also did not observe a relationship between disease severity and either the breadth or magnitude of the T cell response. The T cell epitopes were distributed in a non-random fashion across the viral polyprotein and a limited number of epitopes appeared to dominate the CD8+ T cell response within our cohort. These data provide important new insight into the T cell response against WNV in humans.
Restoration of the CD4 T Cell Compartment after Long-Term Highly Active Antiretroviral Therapy without Phenotypical Signs of Accelerated Immunological Aging
Authors: Vrisekoop Nienke , van Gent Rogier , de Boer Anne Bregje , Otto Sigrid A. , Borleffs Jan C. C. , Steingrover Radjin , Prins Jan M. , Kuijpers Taco W. , Wolfs Tom F. W. , Geelen Sibyl P. M. , Vulto Irma , Lansdorp Peter , Tesselaar Kiki , Borghans José A. M. , Miedema Frank
Published: April 2014

It remains uncertain whether full T cell reconstitution can be established in HIV-infected children and adults with long-term sustained virological control by highly active antiretroviral therapy (HAART). In this study, we comprehensively analyzed various phenotypical markers of CD4 T cell recovery. In addition to measuring T cell activation and proliferation markers, CD4 T cell generation and aging of the CD4 T cell compartment were assessed by measuring TCR excision circles and the fraction of CD31-expressing naive CD4 T cells. In all children and in adults with relatively high CD4 T cell counts at start of therapy (>200 cells/μl), total CD4 T cell numbers normalized within 1 year of therapy. After long-term HAART (4.4–9.6 years), naive CD4 T cell counts had normalized in both groups. Although in adults with low baseline CD4 T cell counts (<200 cells/μl) total CD4 T cell numbers normalized eventually after at least 7 years of HAART, naive CD4 T cell counts had still not recovered. TCR excision circle data showed that thymic T cell production contributed to naive T cell recovery at all ages. The fraction of CD31-expressing naive CD4 T cells was found to be normal, suggesting that the CD4 T cell repertoire was diverse after long-term HAART. Hence, under sustained viral suppression during long-term HAART, the T cell compartment has the potential to fully recover by generating new naive T cells both in children and in adults with high baseline CD4 T cells counts. Irrespective of baseline CD4 T cell counts, reconstitution occurred without a significant effect on T cell aging as reflected by markers for replicative history.
Deficient TACI Expression on B Lymphocytes of Newborn Mice Leads to Defective Ig Secretion in Response to BAFF or APRIL
Authors: Kanswal Sunita , Katsenelson Nora , Selvapandiyan Angamuthu , Bram Richard J. , Akkoyunlu Mustafa
Published: April 2014

Capsular polysaccharides of encapsulated bacteria do not induce immune response in newborns and the mechanism for this unresponsiveness is not clear. In adults, transmembrane activator and calcium-modulator and cytophilin ligand interactor (TACI) is a TNFR family member molecule with a pivotal role in Ab responses against polysaccharide vaccines. We investigated the expression and the functions of the TNF family cytokines, B cell-activating factor of the TNF family (BAFF) and a proliferation-inducing ligand (APRIL), and their receptors in newborn mice and found that TACI expression on B lymphocytes was dramatically reduced (p < 0.0001) in newborns as compared with adults. More importantly, TACI ligands BAFF or APRIL were unable to induce IgA/IgG/IgM secretion from newborn B lymphocytes. Additionally, TACI expression seems to be important in plasma cell development. Indeed, in contrast to adults, stimulation of newborn B lymphocytes with BAFF or APRIL did not result in up-regulation of CD138 expression. In vitro or in vivo exposure of newborn B lymphocytes to oligodeoxynucleotides (CpG ODN) led to up-regulation of TACI expression on newly formed, follicular, and marginal zone as well as B1 B lymphocyte populations, and rendered them responsive to BAFF- or APRIL-mediated CD138 expression and IgA/IgG secretion. Finally, immunization of newborn BALB/c mice but not TACI knockout mice with CpG ODN containing (4-hydroxy-3-nitrophenyl)acetyl-Ficoll led to development of IgG Abs against (4-hydroxy-3-nitrophenyl)acetyl. These findings demonstrate that low TACI expression may be a critical factor that determines the susceptibility of newborns to infections with encapsulated bacteria and the impaired immunogenicity of polysaccharide vaccines. Finally, CpG ODNs may correct deficient newborn response to polysaccharide vaccines by up-regulating TACI.
Cutting Edge: The Transmembrane E3 Ligase GRAIL Ubiquitinates the Costimulatory Molecule CD40 Ligand during the Induction of T Cell Anergy
Authors: Lineberry Neil B. , Su Leon L. , Lin Jack T. , Coffey Greg P. , Seroogy Christine M. , Fathman C. Garrison
Published: April 2014

Activation of naive T lymphocytes is regulated through a series of discrete checkpoints that maintain unresponsiveness to self. During this multistep process, costimulatory interactions act as inducible signals that allow APCs to selectively mobilize T cells against foreign Ags. In this study, we provide evidence that the anergy-associated E3 ubiquitin ligase GRAIL (gene related to anergy in lymphocytes) regulates expression of the costimulatory molecule CD40L on CD4 T cells. Using its luminal protease-associated domain, GRAIL binds to the luminal/extracellular portion of CD40L and facilitates transfer of ubiquitin molecules from the intracellular GRAIL RING (really interesting new gene) finger to the small cytosolic portion of CD40L. Down-regulation of CD40L occurred following ectopic expression of GRAIL in naive T cells from CD40−/− mice, and expression of GRAIL in bone marrow chimeric mice was associated with diminished lymphoid follicle formation. These data provide a model for intrinsic T cell regulation of costimulatory molecules and a molecular framework for the initiation of clonal T cell anergy.
IFN Regulatory Factor-1 Negatively Regulates CD4+CD25+ Regulatory T Cell Differentiation by Repressing Foxp3 Expression
Authors: Fragale Alessandra , Gabriele Lucia , Stellacci Emilia , Borghi Paola , Perrotti Edvige , Ilari Ramona , Lanciotti Angela , Remoli Anna Lisa , Venditti Massimo , Belardelli Filippo , Battistini Angela
Published: April 2014

Regulatory T (Treg) cells are critical in inducing and maintaining tolerance. Despite progress in understanding the basis of immune tolerance, mechanisms and molecules involved in the generation of Treg cells remain poorly understood. IFN regulatory factor (IRF)-1 is a pleiotropic transcription factor implicated in the regulation of various immune processes. In this study, we report that IRF-1 negatively regulates CD4+CD25+ Treg cell development and function by specifically repressing Foxp3 expression. IRF-1-deficient (IRF-1−/−) mice showed a selective and marked increase of highly activated and differentiated CD4+CD25+Foxp3+ Treg cells in thymus and in all peripheral lymphoid organs. Furthermore, IRF-1−/− CD4+CD25− T cells showed extremely high bent to differentiate into CD4+CD25+Foxp3+ Treg cells, whereas restoring IRF-1 expression in IRF-1−/− CD4+CD25− T cells impaired their differentiation into CD25+Foxp3+ cells. Functionally, both isolated and TGF-β-induced CD4+CD25+ Treg cells from IRF-1−/− mice exhibited more increased suppressive activity than wild-type Treg cells. Such phenotype and functional characteristics were explained at a mechanistic level by the finding that IRF-1 binds a highly conserved IRF consensus element sequence (IRF-E) in the foxp3 gene promoter in vivo and negatively regulates its transcriptional activity. We conclude that IRF-1 is a key negative regulator of CD4+CD25+ Treg cells through direct repression of Foxp3 expression.
Low- versus High-Baseline Epinephrine Output Shapes Opposite Innate Cytokine Profiles: Presence of Lewis- and Fischer-Like Neurohormonal Immune Phenotypes in Humans?
Authors: Elenkov Ilia J. , Kvetnansky Richard , Hashiramoto Akira , Bakalov Vladimir K. , Link Amrey A. , Zachman Keith , Crane Marianna , Jezova Daniela , Rovensky Jozef , Dimitrov Mariana A. , Gold Philip W. , Bonini Sergio , Fleisher Thomas , Chrousos George P. , Wilder Ronald L.
Published: April 2014

Immunogenetic mechanisms operating within the immune system are known to influence cytokine profiles and disease susceptibility. Yet the role of the individual’s neurohormonal background in these processes remains undefined. Hormonal imbalances are documented in immune-related diseases, but it is unclear whether this represents a secondary phenomenon or a primary “defect” related to specific neurohormonal immune phenotype(s). We report that in a large subpopulation of healthy humans the baseline epinephrine output (but not cortisol and sex steroid hormones) correlated inversely with proinflammatory and positively with anti-inflammatory cytokine production. Thus, low vs high epinephrine excretors had a 2- to 5-fold higher TNF-α and IL-12 production but 2-fold lower IL-10 production induced by LPS ex vivo. In alternative settings, we found low baseline levels and profoundly blunted stress-induced epinephrine responses but high TNF-α levels in Lewis vs Fischer inbred rats. Additionally, isoproterenol, a β adrenoreceptor agonist suppressed LPS-induced TNF-α production, with more pronounced effect in Lewis than in Fischer rats. In human monocytes, epinephrine and the β2 adrenoreceptor agonist fenoterol potently inhibited LPS-induced TNF-α and IL-12, but stimulated IL-10 production. The order of potency for hormones able to inhibit IL-12 production ex vivo was: epinephrine > norepinephrine > = 1,25-(OH)2 vitamin D3 > hydrocortisone. This indicates that baseline epinephrine conditions cytokine responsiveness and through this mechanism intrinsic hypo- or hyperactive adrenal medullas in some individuals may shape opposite cytokine profiles. Since Lewis and Fischer rats have opposite susceptibility to experimental immunological diseases, this suggests that the parallel human phenotypes could be linked to differing responsiveness and susceptibility to infections and immune/inflammatory-related conditions.
Functional Regulatory T Cells Accumulate in Aged Hosts and Promote Chronic Infectious Disease Reactivation
Authors: Lages Celine S. , Suffia Isabelle , Velilla Paula A. , Huang Bin , Warshaw Gregg , Hildeman David A. , Belkaid Yasmin , Chougnet Claire
Published: April 2014

Declines in immune function are well described in the elderly and are considered to contribute significantly to the disease burden in this population. Regulatory T cells (Tregs), a CD4+ T cell subset usually characterized by high CD25 expression, control the intensity of immune responses both in rodents and humans. However, because CD25 expression does not define all Tregs, especially in aged hosts, we characterized Tregs by the expression of FOXP3, a transcription factor crucial for Treg differentiation and function. The proportion of FOXP3+CD4+ Tregs increased in the blood of the elderly and the lymphoid tissues of aged mice. The expression of functional markers, such as CTLA-4 and GITR, was either preserved or increased on FOXP3+ Tregs from aged hosts, depending on the tissue analyzed. In vitro depletion of peripheral Tregs from elderly humans improves effector T cell responses in most subjects. Importantly, Tregs from old FoxP3-GFP knock-in mice were suppressive, exhibiting a higher level of suppression per cell than young Tregs. The increased proportion of Tregs in aged mice was associated with the spontaneous reactivation of chronic Leishmania major infection in old mice, likely because old Tregs efficiently suppressed the production of IFN-γ by effector T cells. Finally, in vivo depletion of Tregs in old mice attenuated disease severity. Accumulation of functional Tregs in aged hosts could therefore play an important role in the frequent reactivation of chronic infections that occurs in aging. Manipulation of Treg numbers and/or activity may be envisioned to enhance the control of infectious diseases in this fragile population.
Excessive Production of IFN-γ in Patients with Systemic Lupus Erythematosus and Its Contribution to Induction of B Lymphocyte Stimulator/B Cell-Activating Factor/TNF Ligand Superfamily-13B
Authors: Harigai Masayoshi , Kawamoto Manabu , Hara Masako , Kubota Tetsuo , Kamatani Naoyuki , Miyasaka Nobuyuki
Published: April 2014

Expression and immunological significance of IFN-γ, a pivotal cytokine in murine lupus, have not been clearly demonstrated in human systemic lupus erythematosus (SLE). In the present study we investigated the expression of IFN-γ in peripheral blood T cells from patients with SLE and its role in the production of the soluble B lymphocyte stimulator (sBLyS). Peripheral blood T cells from patients with SLE expressed significantly larger amounts of IFN-γ in response to stimulation with anti-CD3 mAb plus anti-CD28 mAb than those from normal controls as shown by three analytical methods, including ELISA, flow cytometry, and quantitative RT-PCR. The ratio of IFN-γ-producing T cells to effector memory T cells in CD3+CD4+ and CD3+CD8+ populations in patients with SLE was significantly higher than that of normal controls. The T-box expressed in T cells (T-bet) mRNA/GATA-binding protein-3 (GATA-3) mRNA ratio was significantly higher in patients with SLE than in normal controls. T cell culture supernatants from patients with SLE contained significantly higher sBLyS-inducing activity than normal controls; this was almost completely inhibited by the addition of anti-human IFN-γ mAb. Percentages of BLyS-expressing peripheral blood monocytes in patients with SLE were significantly higher than those of normal controls. Monocytes from patients with SLE produced significantly larger amounts of sBLyS in response to IFN-γ than those from normal controls. Taken together, these data strongly indicate that the overexpression of IFN-γ in peripheral blood T cells contributes to the immunopathogenesis of SLE via the induction of sBLyS by monocytes/macrophages, which would promote B cell activation and maturation.
TGF-β Promotes Thyroid Epithelial Cell Hyperplasia and Fibrosis in IFN-γ-Deficient NOD.H-2h4 Mice
Authors: Yu Shiguang , Sharp Gordon C. , Braley-Mullen Helen
Published: April 2014

IFN-γ−/−NOD.H-2h4 mice given 0.05% NaI in their water develop severe thyroid epithelial cell (thyrocyte) hyperplasia and proliferation (TEC H/P) and fibrosis. Proliferating thyrocytes of IFN-γ−/− mice with TEC H/P produce TGF-β as demonstrated by immunohistochemical staining and in situ hybridization. Strong expression of activating phosphorylated Smad-2/3 and weak expression of inhibitory Smad-7 by proliferating thyrocytes correlate with the severity of TEC H/P. Splenocytes from IFN-γ−/− mice with severe TEC H/P transfer severe TEC H/P to IFN-γ−/−NOD.H-2h4.SCID mice. Mice given anti-TGF-β had markedly reduced thyrocyte proliferation and decreased fibrosis compared with mouse Ig-treated controls, suggesting that TGF-β plays an important role in development of TEC H/P induced by activated splenocytes. Moreover, transgenic IFN-γ−/−NOD.H-2h4 mice expressing TGF-β on thyrocytes all develop fibrosis and moderate to severe TEC H/P with accelerated kinetics, directly demonstrating a role for TGF-β in severe TEC H/P and fibrosis.
Cells That Produce Deleterious Autoreactive Antibodies Are Vulnerable to Suicide
Authors: Niu Haitao , Leung Danny T. M. , Ma Chun Hung , Law Eric C. Y. , Tam Frankie C. H. , Lim Pak-Leong
Published: April 2014

It is puzzling how autoreactive B cells that escape self-tolerance mechanisms manage to produce Abs that target vital cellular processes without succumbing themselves to the potentially deleterious effects of these proteins. We report that censorship indeed exists at this level: when the Ab synthesis in the cell is up-regulated in IL-6-enriched environments (e.g., adjuvant-primed mouse peritoneum), the cell dies of the increased intracellular binding between the Ab and the cellular autoantigen. In the case in which telomerase is the autoantigen, mouse hybridoma cells synthesizing such an autoantibody, which appeared to grow well in culture, could not grow in syngeneic BALB/c mice to form ascites, but grew nevertheless in athymic siblings. Culture experiments demonstrated that peritoneal cell-derived IL-6 (and accessory factors) affected the growth and functions of the hybridoma cells, including the induction of mitochondria-based apoptosis. Electron microscopy revealed an abundance of Abs in the nuclear chromatin of IL-6-stimulated cells, presumably piggy-backed there by telomerase from the cytosol. This nuclear presence was confirmed by light microscopy analysis of isolated nuclei. In two other cases, hybridoma cells synthesizing an autoantibody to GTP or osteopontin also showed similar growth inhibition in vivo. In all cases, Ab function was crucial to the demise of the cells. Thus, autoreactive cells, which synthesize autoantibodies to certain intracellular Ags, live delicately between life and death depending on the cytokine microenvironment. Paradoxically, IL-6, which is normally growth-potentiating for B cells, is proapoptotic for these cells. The findings reveal potential strategies and targets for immunotherapy.
Thymic Emigration: When and How T Cells Leave Home
Authors: Weinreich Michael A. , Hogquist Kristin A.
Published: April 2014

The thymus supports the differentiation of multiple distinct T cell subsets that play unique roles in the immune system. CD4 and CD8 α/β T cells, γ/δ T cells, NKT cells, regulatory T cells, and intraepithelial lymphocytes all develop in the thymus and must leave it to provide their functions elsewhere in the body. This article will review recent research indicating differences in the time and migration patterns of T cell subsets found in the thymus. Additionally, we review current understanding of the molecules involved in thymocyte emigration, including the sphingolipid receptor S1P1 and its regulation by the Krüppel-like transcription factor KLF2.
Rapid NKT Cell Responses Are Self-Terminating during the Course of Microbial Infection
Authors: Chiba Asako , Dascher Christopher C. , Besra Gurdal S. , Brenner Michael B.
Published: April 2014

NKT cells play a protective role in immune responses against infectious pathogens. However, when the NKT cell response to infection is initiated and terminated is unknown. In this study, we demonstrate that NKT cells become activated, proliferate, and exert their effector function before MHC-restricted T cells during infection with Mycobacterium bovis bacillus Calmette-Guérin in mice. After a cell expansion phase, NKT cells underwent cell death, which contracts their numbers back to baseline. Surprisingly, despite ongoing infection, the remaining NKT cells were profoundly unresponsive to TCR stimulation, while MHC-restricted T cells were vigorously proliferating and producing IFN-γ. Similarly, we show that NKT cells became unresponsive in uninfected mice after receiving a single exposure to a TLR agonist LPS, suggesting that NKT cell unresponsiveness may be a major mechanism of terminating their response in many infectious conditions. This characterization of the NKT cell response in antimicrobial immunity indicates that rapid NKT cell activation contributes to the innate phase of the response to the infectious pathogen, but then, the NKT cell response is shut down by two mechanisms; apoptotic contraction and marked unresponsiveness to TCR stimulation, as a synchronized hand off to MHC-restricted T cells occurs.
Differential Requirement for the SAP-Fyn Interaction during NK T Cell Development and Function
Authors: Nunez-Cruz Selene , Yeo W. C. Janice , Rothman Jennifer , Ojha Priti , Bassiri Hamid , Juntilla Marisa , Davidson Dominique , Veillette André , Koretzky Gary A. , Nichols Kim E.
Published: April 2014

The adaptor molecule SAP (signaling lymphocytic activation molecule-associated protein) plays a critical role during NK T (NKT) cell development in humans and mice. In CD4+ T cells, SAP interacts with the tyrosine kinase Fyn to deliver signals required for TCR-induced Th2-type cytokine production. To determine whether the SAP-dependent signals controlling NKT cell ontogeny rely on its binding to Fyn, we used the OP9-DL1 system to initiate structure function studies of SAP in murine NKT cell development. In cultures containing wild-type (WT) hematopoietic progenitors, we noted the transient emergence of cells that reacted with the NKT cell-specific agonist α-galactosyl ceramide and its analog PBS57. Sap−/− cells failed to give rise to NKT cells in vitro; however, their development could be rescued by re-expression of WT SAP. Emergence of NKT cells was also restored by a mutant version of SAP (SAP R78A) that cannot bind to Fyn, but with less efficiency than WT SAP. This finding was accentuated in vivo in SapR78A knock-in mice as well as SapR78A competitive bone marrow chimeras, which retained NKT cells but at significantly reduced numbers compared with controls. Unlike SapR78A CD4+ T cells, which produce reduced levels of IL-4 following TCR ligation, α-galactosyl ceramide-stimulated NKT cells from the livers and spleens of SapR78A mice produced Th2 cytokines and activated NK cells in a manner mimicking WT cells. Thus, SAP appears to use differential signaling mechanisms in NKT cells, with optimal ontogeny requiring Fyn binding, while functional responses occur independently of this interaction.
Immunosuppressive Effect of Isopropanol: Down-Regulation of Cytokine Production Results from the Alteration of Discrete Transcriptional Pathways in Activated Lymphocytes
Authors: Désy Olivier , Carignan Damien , Caruso Manuel , de Campos-Lima Pedro O.
Published: April 2014

Isopropanol (IPA) is widely used in household applications and constitutes a leading cause of acute alcohol intoxication second only to ethanol. Although the effects of ethanol on the immune system have been extensively studied, far fewer data are available on IPA. Given the structural similarity between the two molecules, we hypothesized that IPA could as well have immunomodulatory properties. We report here that acute IPA exposure is detrimental to human T lymphocyte and NK cell activity in vitro in concentrations as low as 0.08–0.16% (13–26 mM). IPA treatment did not affect receptor-mediated early signaling but had a reproducible and dose-dependent effect on the nuclear translocation of NFAT and AP-1. Furthermore, we show in a model of acute IPA intoxication that animals became immunosuppressed as judged by their reduced ability to release IL-2 and IFN-γ in the serum in response to staphylococcal enterotoxin B. This effect was also associated to the down-regulation of TNF-α production and was sufficiently strong to rescue susceptible animals from enterotoxin-induced toxic shock. Our results suggest that IPA is potentially immunosuppressive to the adaptive and innate immune system and have broad significance given the exposure of the general population to this ubiquitous chemical.
Functional Characterization and Gene Expression Analysis of CD4+CD25+ Regulatory T Cells Generated in Mice Treated with 2,3,7,8-Tetrachlorodibenzo-p-Dioxin
Authors: Marshall Nikki B. , Vorachek William R. , Steppan Linda B. , Mourich Dan V. , Kerkvliet Nancy I.
Published: April 2014

Although the effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) are mediated through binding and activation of the aryl hydrocarbon receptor (AhR), the subsequent biochemical and molecular changes that confer immune suppression are not well understood. Mice exposed to TCDD during an acute B6-into-B6D2F1 graft-vs-host response do not develop disease, and recently this has been shown to correlate with the generation of CD4+ T cells that express CD25 and demonstrate in vitro suppressive function. The purpose of this study was to further characterize these CD4+ cells (TCDD-CD4+ cells) by comparing and contrasting them with both natural regulatory CD4+ T cells (T-regs) and vehicle-treated cells. Cellular anergy, suppressive functions, and cytokine production were examined. We found that TCDD-CD4+ cells actively proliferate in response to various stimuli but suppress IL-2 production and the proliferation of effector T cells. Like natural T-regs, TCDD-CD4+ cells do not produce IL-2 and their suppressive function is contact dependent but abrogated by costimulation through glucocorticoid-induced TNFR (GITR). TCDD-CD4+ cells also secrete significant amounts of IL-10 in response to both polyclonal and alloantigen stimuli. Several genes were significantly up-regulated in TCDD-CD4+ cells including TGF-β3, Blimp-1, and granzyme B, as well as genes associated with the IL12-Rb2 signaling pathway. TCDD-CD4+ cells demonstrated an increased responsiveness to IL-12 as indicated by the phosphorylation levels of STAT4. Only 2% of TCDD-CD4+ cells express Foxp3, suggesting that the AhR does not rely on Foxp3 for suppressive activity. The generation of CD4+ cells with regulatory function mediated through activation of the AhR by TCDD may represent a novel pathway for the induction of T-regs.
Activation of γδ T Cells by Borrelia burgdorferi Is Indirect via a TLR- and Caspase-Dependent Pathway
Authors: Collins Cheryl , Shi Cuixia , Russell Jennifer Q. , Fortner Karen A. , Budd Ralph C.
Published: April 2014

Activation of the innate immune system typically precedes engagement of adaptive immunity. Cells at the interface between these two arms of the immune response are thus critical to provide full engagement of host defense. Among the innate T cells at this interface are γδ T cells. γδ T cells contribute to the defense from a variety of infectious organisms, yet little is understood regarding how they are activated. We have previously observed that human γδ T cells of the Vδ1 subset accumulate in inflamed joints in Lyme arthritis and proliferate in response to stimulation with the causative spirochete, Borrelia burgdorferi. We now observe that murine γδ T cells are also activated by B. burgdorferi and that in both cases the activation is indirect via TLR stimulation on dendritic cells or monocytes. Furthermore, B. burgdorferi stimulation of monocytes via TLR, and secondary activation of γδ T cells, are both caspase-dependent.
Homeostatic Proliferation in the Mice with Germline FoxP3 Mutation and its Contribution to Fatal Autoimmunity
Authors: Chang Xing , Zheng Pan , Liu Yang
Published: April 2014

FoxP3 has emerged as a critical regulator for the development and function of regulatory T cells. Recent studies by several groups have demonstrated that FoxP3 is expressed outside T cell lineages. In this context, we have reported that germline mutation of FoxP3 caused defective thymopoiesis, although its potential contribution to autoimmune diseases has not been analyzed. In this study, we report that, during perinatal period, germline mutation of FoxP3 in scurfy mice caused lymphopenia in the spleen and massive homeostatic proliferation, characterized by the independence from cognate Ags and expression of bona fide markers for homeostatic proliferation. The homeostatic proliferation is suppressed by increases in T cell numbers but not by adoptive transfer of regulatory T cells (Treg). Adoptive transfer of Treg-containing bulk T cells was dramatically more effective than transfer of either Treg alone or Treg-depleted CD4 T cells in curing the scurfy mice. Our data demonstrated that FoxP3 mutation not only ablates Treg, but also dramatically increased homeostatic proliferation during the perinatal period. Homeostatic proliferation acts in concert with Treg defects in causing acute and fatal autoimmune diseases in the FoxP3 mutant mice. These results demonstrated that germline mutation of FoxP3 caused two defects that work in concert to cause lethal autoimmunity.
Colonization with Heligmosomoides polygyrus Suppresses Mucosal IL-17 Production
Authors: Elliott David E. , Metwali Ahmed , Leung John , Setiawan Tommy , Blum Arthur M. , Ince M. Nedim , Bazzone Lindsey E. , Stadecker Miguel J. , Urban Joseph F. , Weinstock Joel V.
Published: April 2014

Helminth exposure appears to protect hosts from inappropriate inflammatory responses, such as those causing inflammatory bowel disease. A recently identified, strongly proinflammatory limb of the immune response is characterized by T cell IL-17 production. Many autoimmune type inflammatory diseases are associated with IL-17 release. Because helminths protect from these diseases, we examined IL-17 production in helminth-colonized mice. We colonized mice with Heligmosomoides polygyrus, an intestinal helminth, and analyzed IL-17 production by lamina propria mononuclear cells (LPMC) and mesenteric lymph node (MLN) cells. Colonization with H. polygyrus reduces IL-17A mRNA by MLN cells and inhibits IL-17 production by cultured LPMC and MLN cells. Helminth exposure augments IL-4 and IL-10 production. Blocking both IL-4 and IL-10, but not IL-10 alone, restores IL-17 production in vitro. Colonization of colitic IL-10-deficient mice with H. polygyrus suppresses LPMC IL-17 production and improves colitis. Ab-mediated blockade of IL-17 improves colitis in IL-10-deficient mice. Thus, helminth-associated inhibition of IL-17 production is most likely an important mechanism mediating protection from inappropriate intestinal inflammation.
CD11c+CD11b+ Dendritic Cells Play an Important Role in Intravenous Tolerance and the Suppression of Experimental Autoimmune Encephalomyelitis
Authors: Li Hongmei , Zhang Guang-Xian , Chen Youhai , Xu Hui , Fitzgerald Denise C. , Zhao Zhao , Rostami Abdolmohamad
Published: April 2014

The central role of T cells in the induction of immunological tolerance against i.v. Ags has been well documented. However, the role of dendritic cells (DCs), the most potent APCs, in this process is not clear. In the present study, we addressed this issue by examining the involvement of two different DC subsets, CD11c+CD11b+ and CD11c+CD8+ DCs, in the induction of i.v. tolerance. We found that mice injected i.v. with an autoantigen peptide of myelin oligodendrocyte glycoprotein (MOG) developed less severe experimental autoimmune encephalomyelitis (EAE) following immunization with MOG peptide but presented with more CD11c+CD11b+ DCs in the CNS and spleen. Upon coculturing with T cells or LPS, these DCs exhibited immunoregulatory characteristics, including increased production of IL-10 and TGF-β but reduced IL-12 and NO; they were also capable of inhibiting the proliferation of MOG-specific T cells and enhancing the generation of Th2 cells and CD4+CD25+Foxp3+ regulatory T cells. Furthermore, these DCs significantly suppressed ongoing EAE upon adoptive transfer. These results indicate that CD11c+CD11b+ DCs, which are abundant in the CNS of tolerized animals, play a crucial role in i.v. tolerance and EAE and may be a candidate cell population for immunotherapy of autoimmune diseases.
CD46-Induced Immunomodulatory CD4+ T Cells Express the Adhesion Molecule and Chemokine Receptor Pattern of Intestinal T Cells
Authors: Alford Shannon K. , Longmore Gregory D. , Stenson William F. , Kemper Claudia
Published: April 2014

Tissue homing of activated T cells is typically mediated through their specific integrin and chemokine receptor repertoire. Activation of human primary CD4+ T cells in the presence of CD46 cross-linking induces the development of a distinct immunomodulatory T cell population characterized by high IL-10/granzyme B production. How these regulatory T cells (Tregs) migrate/home to specific tissue sites is not understood. In this study, we determined the adhesion protein and chemokine receptor expression pattern on human CD3/CD46-activated peripheral blood CD4+ T cells. CD3/CD46-activated, but not CD3/CD28-activated, T cells up-regulate the integrin α4β7. The interaction of α4β7 with its ligand mucosal addressin cell adhesion molecule 1 (MAdCAM-1) mediates homing or retention of T cells to the intestine. CD3/CD46-activated Tregs adhere to/roll on MAdCAM-1-expressing HeLa cells, similar to T cells isolated from the human lamina propria (LP). This interaction is inhibited by silencing MAdCAM-1 expression in HeLa cells or by the addition of blocking Abs to β7. CD46 activation of T cells also induced the expression of the surface-bound cytokine LIGHT and the chemokine receptor CCR9, both marker constitutively expressed by gut LP-resident T cells. In addition, we found that ∼10% of the CD4+ T lymphocytes isolated from the LP of patients undergoing bariatric surgery contain T cells that spontaneously secrete a cytokine pattern consistent with that from CD46-activated T cells. These data suggest that CD46-induced Tregs might play a role in intestinal immune homeostasis where they could dampen unwanted effector T cell responses through local IL-10/granzyme B production.