Promotes IL-10 Production Research Articles

Role of IL‐10‐producing regulatory B cells in control of cerebral malaria in Plasmodium berghei infected mice

Cerebral malaria (CM) is a neurological syndrome often occurring in severe malaria. Although CM is known as an immunopathology in brain tissue mediated by excessive proinflammatory cytokines, the immunoregulatory mechanism is poorly understood. Here, we investigated the role of IL-10-producing regulatory B (Breg) cells in modulating CM development in a murine model of Plasmodium berghei ANKA infection. We observed that blood-stage P. berghei induced expansion of IL-10-producing Breg cells in C57BL/6 mice. Adoptive transfer of IL-10(+) Breg cells to P. berghei infected mice significantly reduced the accumulation of NK and CD8(+) T cells and hemorrhage in brain tissue, and improved the survival of the mice compared with control groups, although parasitemia levels were not altered. Treatment of Breg-cell recipient mice with anti-IL-10 receptor mAb blocked the protective effect of Breg cells. Adoptive transfer of CD4(+) CD25(+) Treg cells failed to prevent CM in infected mice. Spleen cells from Breg-cell recipient mice produced increased levels of IL-10 in vitro. Cell co-culture showed that purified IL-10(+) B cells, but not IL-10(-) B cells, promoted IL-10 production by CD4(+) T cells. These results demonstrate that IL-10-producing Breg cells may represent an important mechanism for controlling the immunopathology and prevention of CM associated with P. berghei infection.

TPL-2–ERK1/2 Signaling Promotes Host Resistance against Intracellular Bacterial Infection by Negative Regulation of Type I IFN Production

Tuberculosis, caused by Mycobacterium tuberculosis, remains a leading cause of mortality and morbidity worldwide, causing ≈ 1.4 million deaths per year. Key immune components for host protection during tuberculosis include the cytokines IL-12, IL-1, and TNF-α, as well as IFN-γ and CD4(+) Th1 cells. However, immune factors determining whether individuals control infection or progress to active tuberculosis are incompletely understood. Excess amounts of type I IFN have been linked to exacerbated disease during tuberculosis in mouse models and to active disease in patients, suggesting tight regulation of this family of cytokines is critical to host resistance. In addition, the immunosuppressive cytokine IL-10 is known to inhibit the immune response to M. tuberculosis in murine models through the negative regulation of key proinflammatory cytokines and the subsequent Th1 response. We show in this study, using a combination of transcriptomic analysis, genetics, and pharmacological inhibitors, that the TPL-2-ERK1/2 signaling pathway is important in mediating host resistance to tuberculosis through negative regulation of type I IFN production. The TPL-2-ERK1/2 signaling pathway regulated production by macrophages of several cytokines important in the immune response to M. tuberculosis as well as regulating induction of a large number of additional genes, many in a type I IFN-dependent manner. In the absence of TPL-2 in vivo, excess type I IFN promoted IL-10 production and exacerbated disease. These findings describe an important regulatory mechanism for controlling tuberculosis and reveal mechanisms by which type I IFN may promote susceptibility to this important disease.

Interleukin (IL)-32β-mediated CCAAT/Enhancer-binding Protein α (C/EBPα) Phosphorylation by Protein Kinase Cδ (PKCδ) Abrogates the Inhibitory Effect of C/EBPα on IL-10 Production

We previously reported that IL-32β promotes IL-10 production in myeloid cells. However, the underlying mechanism remains elusive. In this study, we demonstrated that IL-32β abrogated the inhibitory effect of CCAAT/enhancer-binding protein α (C/EBPα) on IL-10 expression in U937 cells. We observed that the phosphorylation of C/EBPα Ser-21 was inhibited by a PKCδ-specific inhibitor, rottlerin, or IL-32β knockdown by siRNA and that IL-32β shifted to the membrane from the cytosol upon phorbol 12-myristate 13-acetate treatment. We revealed that IL-32β suppressed the binding of C/EBPα to IL-10 promoter by using ChIP assay. These data suggest that PKCδ and IL-32β may modulate the effect of C/EBPα on IL-10 expression. We next demonstrated by immunoprecipitation that IL-32β interacted with PKCδ and C/EBPα, thereby mediating C/EBPα Ser-21 phosphorylation by PKCδ. We showed that IL-32β suppressed the inhibitory effect of C/EBPα on IL-10 promoter activity. However, the IL-10 promoter activity was reduced to the basal level by rottlerin treatment. When C/EBPα serine 21 was mutated to glycine (S21G), the inhibitory effect of C/EBPα S21G on IL-10 promoter activity was not modulated by IL-32β. Taken together, our results show that IL-32β-mediated C/EBPα Ser-21 phosphorylation by PKCδ suppressed C/EBPα binding to IL-10 promoter, which promoted IL-10 production in U937 cells.

A Single Strain of Clostridium butyricum Induces Intestinal IL-10-Producing Macrophages to Suppress Acute Experimental Colitis in Mice

Imbalance in gut bacterial composition provokes host proinflammatory responses causing diseases such as colitis. Colonization with a mixture of Clostridium species from clusters IV and XIVa was shown to suppress colitis through the induction of IL-10-producing regulatory T (Treg) cells. We demonstrate that a distinct Clostridium strain from cluster I, Clostridium butyricum (CB), prevents acute experimental colitis in mice through induction of IL-10, ananti-inflammatory cytokine. However, while CBtreatmenthad no effect on IL-10 production byTcells,IL-10-producing F4/80(+)CD11b(+)CD11c(int) macrophages accumulated in the inflamed mucosa after CB treatment. CB directly triggered IL-10 production by intestinal macrophages in inflamed mucosa via the TLR2/MyD88 pathway. The colitis-preventing effect of CB was negated in macrophage-specific IL-10-deficient mice, suggesting that induction of IL-10 by intestinal macrophages is crucial for the probiotic action of CB. Collectively, CB promotes IL-10 production by intestinal macrophages in inflamed mucosa, thereby preventing experimental colitis in mice.

ATF4 is induced by ROS and regulates Th1 and Th17 cells (P6219)

Abstract Reactive oxygen species (ROS) play a major role in the pathogenesis of chronic inflammatory and autoimmune diseases. It is well established that ROS modulate T cell-mediated immune responses. However, little is known about underlying molecular mechanisms of how ROS regulate T cell immune responses and how T cells adapt to high levels of ROS. We demonstrated that ROS induced ATF4 in activated T cells. ATF4 is a basic leucine-zipper (bZip) transcription factor, which regulates cellular redox state and amino acid metabolism. We found that, in the high ROS condition, ATF4-/- Th1 cells failed to produce IFN-γ whereas WT Th1 cells still made large amounts of IFN-γ. Inhibition of ROS by addition of antioxidants recovered the IFN-γ production by ATF4-/- Th1 cells, suggesting ATF4 is critically required for the function of Th1 cells in the presence of high levels of ROS. ATF4-/- antigen presenting cells (APC) promoted IL-17 production, suggesting ATF4 plays an important role in APCs in suppressing Th17-driving cytokines. In addition, we demonstrated that experimental allergic encephalomyelitis (EAE) was exacerbated in ATF4 deficient mice compared with wild type (WT) mice. The number of autoreactive Th1 cells was decreased whereas that of autoreactive Th17 cells was elevated in ATF4-/- mice compared with WT mice. Our study establishes that ATF4 promotes Th1 and suppresses Th17 immune responses and likely plays an important role in autoimmunity and cancer immunology.

CD4+Foxp3+CD25+ regulatory T cells differentiate into IL-17-producing cells and promote immunopathology during Chlamydia genital tract infection (P3211)

Abstract CD4+FoxP3+CD25+ regulatory T cells (Tregs) have been shown to promote de novo Th17 differentiation and to themselves convert into IL-17-producing cells in certain inflammatory settings. However, whether Tregs can potentiate IL-17/Th17 responses to intracellular bacterial infection has not been established. Using a murine model of Chlamydia, we found that Tregs produced IL-17 upon Chlamydia infection and promoted IL-17 production by conventional CD4+ T cells in vitro. Correspondingly, in vivo depletion of Tregs by anti-CD25 antibody dramatically reduced the induction of IL-17-producing CD4+ T cells during Chlamydia genital tract infection. Consistent with reduced IL-17 responses, Treg-depleted mice displayed striking amelioration of neutrophil infiltration and pathology in genital tract tissue relative to control mice, despite comparable bacterial burden throughout the course of infection. Collectively, our data demonstrate an important role for Tregs in promoting IL-17/Th17 responses during intracellular bacterial infection.

Self dsDNA induces IL-1β production from human monocytes by activating NLRP3 inflammasome in the presence of anti-dsDNA antibodies (P4083)

Abstract The pathogenic hallmark of systemic lupus erythematosus (SLE or lupus) is the autoimmune response against self nuclear antigens, including dsDNA. The increased expression of the pro-inflammatory cytokine IL-1β has been found in the cutaneous lesion and peripheral blood mononuclear cells from lupus patients, suggesting a potential involvement of this cytokine in the pathogenesis of lupus. IL-1β is produced primarily by innate immune cells like monocytes and can promote Th17 cell response, which is increased in lupus. IL-1β production requires cleaving pro-IL-β into IL-1β by the caspase-1-associated multiprotein complex called inflammasomes. Here we show that self dsDNA induces IL-1β production from human monocytes dependently of serum or purified IgG containing anti-dsDNA antibodies by activating the NLRP3 inflammasome. Reactive oxygen species (ROS) and K+ efflux were involved in this activation. Knocking down the NLRP3 or inhibiting caspase-1, ROS and K+ efflux decreased IL-1β production. Supernatants from monocytes treated with a combination of self dsDNA and anti-dsDNA antibody-positive serum promoted IL-17 production from CD4+ T cells in an IL-1β dependent manner. These findings provide new insights in lupus pathogenesis by demonstrating that self dsDNA together with its autoantibodies induces IL-1β production from human monocytes by activating the NLRP3 inflammasome through inducing ROS synthesis and K+ efflux, leading to the increased Th17 cell response.

T Follicular Helper Cells Mediate Expansion of Regulatory B Cells via IL-21 in Lupus-Prone MRL/lpr Mice

T follicular helper (Tfh) cells can mediate humoral immune responses and augment autoimmunity, whereas the role of Tfh cells on regulatory B (B10) cells in autoimmunity diseases is not clear. Here, we investigated the percentages of Tfh cells and B10 cells in lupus-prone MRL/Mp-lpr/lpr (MRL/lpr) mice and examined the effects and mechanism of Tfh cell-derived interleukin-21 (IL-21) on IL-10 production during the differentiation of B10 cells. Both Tfh cells and B10 cells were expanded in spleens of MRL/lpr mice. In addition, a positive correlation between the proportions of Tfh cells and B10 cells was observed. Tfh cell-derived IL-21 from MRL/lpr mice could promote IL-10 production during the differentiation of B10 cells. Importantly, neutralization of IL-21 inhibited IL-10 production and expansion of B10 cells both in vitro and in vivo. IL-21 induced IL-10 production via activation of phosphorylated signal transduction and activator of transcription 3 (p-STAT3). Inhibition of p-STAT3 effectively blocked IL-10 production during the differentiation of B10 cells. Moreover, IL-21-induced IL-10 exerted a regulatory function by inhibiting the proliferation of T cells. These data suggest that Tfh cells not only mediate humoral immune responses and augment autoimmunity but also play a broader role in immune regulatory actions via the induction of IL-10 production.

Ephedrine hydrochloride inhibits PGN-induced inflammatory responses by promoting IL-10 production and decreasing proinflammatory cytokine secretion via the PI3K/Akt/GSK3β pathway

Approaches for controlling inflammatory responses and reducing the mortality rate of septic patients remain clinically ineffective; new drugs need to be identified that can induce anti-inflammatory responses. Ephedrine hydrochloride (EH) is a compound that is widely used in cardiovascular diseases, especially to treat hypotension caused by either anesthesia or overdose of antihypertensive drugs. In this study, we reported that EH also plays an important role in the control of the inflammatory response. EH increased IL-10 and decreased proinflammatory cytokine (IL-6, tumor-necrosis factor (TNF)-α, IL-12 and IL-1β) expression in primary peritoneal macrophages and Raw264.7 cells treated with peptidoglycan (PGN), a Gram-positive cell wall component. The anti-inflammatory role of EH was also demonstrated in an experimental mouse model of peritonitis induced by intraperitoneal PGN injection. The phosphatidylinositol 3-kinase (PI3K)/Akt pathway was found to be responsible for the EH-mediated increase in IL-10 production and decrease in IL-6 expression. Therefore, our results illustrated that EH can help maintain immune equilibrium and diminish host damage by balancing the production of pro- and anti-inflammatory cytokines after PGN challenge. EH may be a new potential anti-inflammatory drug that can be useful for treating severe invasive Gram-positive bacterial infection.

The role of inflammasome-derived IL-1 in driving IL-17 responses

NLRs are members of the PRR family that sense microbial pathogens and mediate host innate immune responses to infection. Certain NLRs can assemble into a multiprotein complex called the inflammasome, which activates casapse-1 required for the cleavage of immature forms of IL-1β and IL-18 into active, mature cytokines. The inflammasome is activated by conserved, exogenous molecules from microbes and nonmicrobial molecules, such as asbestos, alum, or silica, as well as by endogenous danger signals, such as ATP, amyloid-β, and sodium urate crystals. Activation of the inflammasome is a critical event triggering IL-1-driven inflammation and is central to the pathology of autoinflammatory diseases, such as gout and MWS. Recent studies have also shown IL-1 or IL-18, in synergy with IL-23, can promote IL-17-prduction from Th17 cells and γδ T cells, and this process can be regulated by autophagy. IL-1-driven IL-17 production plays a critical role in host protective immunity to infection with fungi, bacteria, and certain viruses. However, Th17 cells and IL-17-seceting γδ T cells, activated by inflammasome-derived IL-1 or IL-18, have major pathogenic roles in many autoimmune diseases. Consequently, inflammasomes are now major drug targets for many autoimmune and chronic inflammatory diseases, as well as autoinflammatory diseases.

Self Double-Stranded (ds)DNA Induces IL-1β Production from Human Monocytes by Activating NLRP3 Inflammasome in the Presence of Anti–dsDNA Antibodies

The pathogenic hallmark of systemic lupus erythematosus is the autoimmune response against self nuclear Ags, including dsDNA. The increased expression of the proinflammatory cytokine IL-1β has been found in the cutaneous lesion and PBMCs from lupus patients, suggesting a potential involvement of this cytokine in the pathogenesis of lupus. IL-1β is produced primarily by innate immune cells such as monocytes and can promote a Th17 cell response, which is increased in lupus. IL-1β production requires cleaving pro-IL-β into IL-1β by the caspase-1-associated multiprotein complex called inflammasomes. In this study we show that self dsDNA induces IL-1β production from human monocytes dependent on serum or purified IgG containing anti-dsDNA Abs by activating the nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome. Reactive oxygen species (ROS) and K(+) efflux were involved in this activation. Knocking down the NLRP3 or inhibiting caspase-1, ROS, and K(+) efflux decreased IL-1β production. Supernatants from monocytes treated with a combination of self dsDNA and anti-dsDNA Ab(+) serum promoted IL-17 production from CD4(+) T cells in an IL-1β-dependent manner. These findings provide new insights in lupus pathogenesis by demonstrating that self dsDNA together with its autoantibodies induces IL-1β production from human monocytes by activating the NLRP3 inflammasome through inducing ROS synthesis and K(+) efflux, leading to the increased Th17 cell response.

Transcription factor T-bet regulates intestinal inflammation mediated by innate lymphoid cells with the interleukin-7 receptor

Interactions between the innate immune system and the intestinal microbiota have an important role in the maintenance of mucosal homoeostasis. Indeed, impaired regulation of innate immune pathways are now considered to be a key driver of gut inflammation and may lead to the emergence of inflammatory bowel disease, such as ulcerative colitis or Crohn's disease. Mice lacking the transcription factor T-bet in the innate immune system develop microbiota-dependent colitis that resembles ulcerative colitis. Here, we show that inflammatory bowel disease in this model is mediated by a newly discovered population of innate immune cells termed innate lymphoid cells (ILCs) that selectively produce the inflammatory cytokine interleukin (IL) 17A. Depletion of intestinal ILCs, or blockade of the IL23/IL17 axis significantly attenuated chronic inflammatory bowel disease in these mice.We also show that elevated colonic production of tumour necrosis factor α (TNFα), a key cytokine involved in the pathogenesis of inflammatory bowel disease, was produced by CD103– CD11b+ intestinal dendritic cells (DCs). TNFα synergised with IL23 to drive IL-17A production by ILCs, demonstrating a previously unrecognised layer of cellular crosstalk between DCs and ILCs.Other cytokines implicated in pathogenesis of inflammatory bowel disease, such as TL1A and IL6, also promoted IL-17 production by ILCs, indicating that this novel intestinal innate immune cell population is responsive to other recognised inflammatory signals to drive gut inflammation. By sequencing bacterial rRNA genes we also identify a particular component of the intestinal microbiota of TRUC mice that drives excess TNF-α production and triggers colitis. Lastly, we show that T-bet is a transcriptional repressor of IL-7R expression, a key molecule involved in controlling intestinal ILC homoeostasis. The importance of IL-7R signalling in TRUC disease was highlighted by the dramatic reduction in intestinal ILCs and attenuated colitis following IL-7R blockade.Taken together, these data demonstrate the mechanism by which T-bet regulates the complex interplay between mucosal DCs, ILCs, and the intestinal microbiota. FundingWellcome Trust.

Self-Glycolipids Modulate Dendritic Cells Changing the Cytokine Profiles of Committed Autoreactive T Cells

The impact of glycolipids of non-mammalian origin on autoimmune inflammation has become widely recognized. Here we report that the naturally occurring mammalian glycolipids, sulfatide and β-GalCer, affect the differentiation and the quality of antigen presentation by monocyte-derived dendritic cells (DCs). In response to sulfatide and β-GalCer, monocytes develop into immature DCs with higher expression of HLA-DR and CD86 but lower expression of CD80, CD40 and CD1a and lower production of IL-12 compared to non-modulated DCs. Self-glycolipid-modulated DCs responded to lipopolysaccharide (LPS) by changing phenotype but preserved low IL-12 production. Sulfatide, in particular, reduced the capacity of DCs to stimulate autoreactive Glutamic Acid Decarboxylase (GAD65) - specific T cell response and promoted IL-10 production by the GAD65-specific clone. Since sulfatide and β-GalCer induced toll-like receptor (TLR)-mediated signaling, we hypothesize that self-glycolipids deliver a (tolerogenic) polarizing signal to differentiating DCs, facilitating the maintenance of self-tolerance under proinflammatory conditions.

Human eosinophils release IL‐1ß and increase expression of IL‐17A in activated CD4+ T lymphocytes

Differentiation and activation of CD4(+) T cells is controlled by various cytokines produced by innate immune cells. We have shown that eosinophils (EOS) have the potential to influence Th1 and Th2 cytokine generation by CD4(+) cells, but their influence on IL-17A (IL-17) has not been established. The purpose of this study is to determine the effect of EOS on IL-17 production by lymphocytes. Pre-activated CD4(+) T cells were cultured in the presence of either autologous EOS or EOS culture supernatants. Expression of IL-17 was determined by real-time quantitative PCR (qPCR) after 5 h and protein level was measured after 48 h. To determine the effect of allergen-induced airway EOS on IL-17, subjects with mild allergic asthma underwent bronchoscopic segmental bronchoprovocation with allergen (SBP-Ag) after a treatment with an anti-IL-5 neutralizing antibody (mepolizumab) to reduce airway eosinophilia. IL-17 mRNA was measured in bronchoalveolar lavage (BAL) cells by qPCR. In vitro, EOS significantly increased IL-17 production by CD4(+) T cells. Addition of exogenous IL-1ß increased expression of IL-17 mRNA by CD4(+) T cells. EOS expressed and released IL-1ß. Furthermore, levels of IL-1ß in EOS supernatants highly correlated with their ability to increase IL-17 expression by CD4(+) T cells, and neutralizing antibody to IL-1ß reduced expression of IL-17 mRNA. In vivo, reduction of EOS in the airway using mepolizumab was associated with diminished IL-17 expression after SBP-Ag. Our data demonstrate that EOS can promote IL-17 production through the release of IL-1ß. Enhanced IL-17 cytokine production is another mechanism by which EOS may participate in pathogenesis of allergic airway inflammation in asthma.

Differential effects of LPS from Escherichia coli and Porphyromonas gingivalis on IL-6 production in human periodontal ligament cells

Objective. Periodontal ligament (PDL) cells produce IL-6 upon stimulation with inflammation promoters, but the signaling pathways involved have not been characterized. This study investigates underlying mechanisms behind regulation of PDL cell IL-6 production by E. coli and P. gingivalis LPS. Materials and methods: Human PDL cells, endothelial cells and monocytes were stimulated with E. coli or P. gingivalis LPS in the presence or absence of pharmacological agents in order to disclose pathways involved in LPS signaling. Gene expression and cellular protein levels were assessed by quantitative real-time PCR and ELISA, respectively. Results. Stimulation with LPS from E. coli (1 µg/ml) for 24 h enhanced PDL cell IL-6 expression several fold, demonstrated both on transcript and protein levels, but P. gingivalis LPS (1–5 µg/ml) had no effect. TLR2 mRNA was more highly expressed than TLR4 transcript in PDL cells. Treatment with the non-selective nitric oxide synthase inhibitor L-NAME (100 µM) reduced E. coli LPS-induced PDL cell IL-6 by 30%, while neither aminoguanidine (10 µM), an inhibitor of inducible nitric oxide synthase, nor estrogen (17β-estradiol, 100 nM) influenced IL-6. Treatment with the glucocorticoid dexamethasone (1 µM) totally prevented the E. coli LPS-induced PDL cell IL-6. In endothelial cells, neither E. coli LPS nor P. gingivalis LPS promoted IL-6 production. In monocytes, serving as positive control, both E. coli and P. gingivalis LPS stimulated IL-6. Conclusions. E. coli LPS but not P. gingivalis LPS stimulates PDL cell IL-6 production through a glucocorticoid-sensitive mechanism involving nitric oxide formation, probably via endothelial nitric oxide synthase.

Immunological effect of high mobility group box-1 protein on regulatory dendritic cells and corresponding mechanism

Objective To observe the effects of high mobility group box-1 protein ( HMGB1 ) on function of murine spleen IL-10-producing dendritic cells (DCs) subset CD11clowCD45RBhighDCs.Methods Splenic CD11clowCD45RBhighDCs and CD4 +T cells in Balb/c mice were purified by magnetic beads sorting.CD11clowCD45RBhighDCs were treated with various doses of HMGB1 (0,20,100,500ng/ml).Flow cytometry was used to determine expressions of CD11clowCD45RBhighDC surface molecules including CD40,CD80,CD86,Ⅰ-a/e and Toll-like receptor (TLR) 4.IL-10 level in CD11clow CD45RBhighDC culture supernatants was determined by ELISA method.The CD4+ T cells were divided into four groups: control group (without only treatment),untreated group (HMGB1-untreated CD11clow CD45RBhigh DCs plus CD4+T cells),high-dose HMGB1-treated group (500 ng/ml HMGB1-treated CD11clowCD45RBhigh DCs plus CD4 +T cells),high-dose HMGB1-treated + antibody 1 group (500 ng/ml HMGB1-treated CD11clowCD45RBhigh DCs plus IL-10 antibody and CD4+T cells),high-dose HMGB1-treated + antibody 2 group (500 ng/ml HMGB1-treated CD11clow CD45RBhigh DCs plus homotype IL-10 antibody and CD4 +T cells).IL-4 as well as interferon( IFN-γ) contents in CD4 + T cell culture supernatants were determined by flow cytometry.Results HMGB1 could markedly enhance the expressions of CD40,CD86 and TLR4 on CD11clowCD45RBhigh DC surface as well as level of IL-10 secreted by CD11clow CD45RBhigh DCs as compared with the non-HMGB1 treatment.Meantime,the secretion of IL-10 was HMGB1 concentration dependent.IFN-γ level in high-dose HMGB1-treated group was (279 ± 17) pg/ml,which was markedly lower than that in the untreated group [ (963 ± 11 ) pg/ml,P ＜ 0.05 ].IL-4 level in high-dose HMGB1-treated group was (372 ± 14) pg/ml,which was significantly higher than that in the untreated group [ (213 ± 10) pg/ml,P ＜0.05) \].Conclusions HMGB1 promotes IL-10 production in CD11clowCD45RBhighDCs,induces the differentiation of CD4 +T cells to Th2 cells and downregulates the immune response via activating CD11clowCD45RBhigh DCs. Key words: High mobility group proteins; T-lymphocytes, regulatory; Immunity

Epicutaneous Exposure to Staphylococcal Superantigen Enterotoxin B Enhances Allergic Lung Inflammation via an IL-17A Dependent Mechanism

Atopic dermatitis (AD) is the initial step of the atopic march: the progression from AD to allergic rhinitis and asthma. There is a close association between skin barrier abnormalities and the development of AD and the atopic march. One of cardinal features of AD is that the lesional skin of the majority of AD patients is chronically colonized with Staphylococcus aureus with half isolates producing superantigen enterotoxin B (SEB). Although diverse roles of SEB in the pathogenesis and severity of AD have been recognized, whether SEB contributes to the dermal inflammation that drives lung inflammation and airway hyperresponsiveness (AHR) has not been examined. Here we show a novel role of S. aureus superantigen SEB in augmenting allergen ovalbumin (Ova) induced atopic march through an IL-17A dependent mechanism. When mice epicutaneously (EC) sensitized with allergen Ova, addition of topical SEB led to not only augmented systemic Th2 responses but also a markedly exaggerated systemic Th17/IL-17 immune environment. The ability of SEB in enhancing Th17/IL-17 was mediated through stimulating lymphocytes in spleen and draining lymph nodes to promote IL-6 production. Epicutaneous sensitization of mice with a combination of Ova and SEB significantly enhanced Ova-induced AHR and granulocytic lung inflammation than Ova allergen alone. When IL-17A was deleted genetically, the effects of SEB on augmenting lung inflammation and AHR were markedly diminished. These findings suggest that chronic heavy colonization of enterotoxin producing S. aureus in the skin of patients with atopic dermatitis may have an important role in the development of atopic march via an IL-17A dependent mechanism.

TWEAK promotes the production of Interleukin-17 in rheumatoid arthritis

Tumor necrosis factor (TNF)-like weak inducer of apoptosis (TWEAK) is an inflammatory cytokine that modulates several biological responses by inducing chemokines and proinflammatory cytokines. We hypothesized that TWEAK could promote secretion of IL-17, an amplifier of inflammatory arthritis. To test this, we investigated the capacity of TWEAK to induce IL-17 production in T cells via the fibroblast growth factor-inducible gene 14 (Fn14, also known as TWEAK receptor) signal pathway in rheumatoid arthritis (RA). Fn14 and IL-17 were highly expressed in arthritic tissues of collagen-induced arthritis (CIA) mice. TWEAK induced production of IL-17 alone and synergistically with lipopolysaccharide. In naïve murine T cells, TWEAK promoted Th17 differentiation. The expression of Fn14 was predominant in Th17 cells. TWEAK and IL-17 concentrations were significantly higher in synovial fluid and serum in RA patients than OA patients. In addition, we identified CD4+IL-17+Fn14+ cells in synovium from RA patients. TWEAK promoted IL-17 production synergistically with IL-23 or IL-21 and blockade of Fn14 with Fn14-Fc suppressed Th17 differentiation. Conversely, this treatment enhanced Treg differentiation. These results suggest that TWEAK induces IL-17 production and may be a therapeutic target in the treatment of RA.

STAT4 isoforms are biomarkers in patients with inflammatory bowel disease (51.2)

Abstract Crohn’s disease (CD) and ulcerative colitis (UC), the major forms of inflammatory bowel disease (IBD) in humans are characterized by chronic relapsing inflammation of the gastrointestinal tract (GI). Th1 and Th17 cells have been implicated as important mediators of IBD. Signal transducer and activator of transcription (STAT4) is critical for the development of Th1 cells and promotes IL-17 production from Th17 cells. STAT4 is expressed as two isoforms, a full-length STAT4α, and STAT4β that lacks the C-terminal transactivation domain. In a previous study we found that although both isoforms mediate inflammation in a mouse model of colitis, STAT4β seems more potent in generating tissue inflammation. With this we hypothesized that if STAT4β is more pro-inflammatory, ratios of the isoforms might change in disease. Compared to healthy controls, we observed increased STAT4β/STAT4α ratios in the peripheral blood mononuclear cells of UC and CD patients, correlating with the disease and ratios were normalized after patient treatment. Increased STAT4β/STAT4α ratios in GI biopsies of CD patients further confirmed that ratios correlate with the location and grade of inflammation. In contrast, we did not observe changes in STAT4β/STAT4α ratios in biopsy specimens from eosinophilic esophagitis (EE) patients. Collectively, these data indicate that STAT4 isoforms could be an important non-invasive biomarker in the diagnosis and treatment of IBD, and potentially other inflammatory diseases.

Type I IFN promotes IL-10 production from Th17 cells to suppress autoimmune inflammation (123.17)

Abstract Recent studies reveal a considerable degree of heterogeneity and flexibility in T-cell lineage differentiation, particularly in the development of Th17 cells. However, how the immune system regulates the plasticity of CD4 T cells in vivo during pathogen infection or autoimmunity is poorly defined. In this study, we investigated the direct effects of type I IFN (IFNα/β) on Th17 cell differentiation and plasticity. In this study, we demonstrate that the plasticity of Th17 cells could be influenced by IFNα/β. Our data show that IFNβ treatment of T cells cultured under Th17 polarizing conditions resulted in reduced production of IL-17, but increased production of IL-10. Furthermore, type I IFN induced IL-10 production by antigen specific T cells derived from immunized mice. We also found that IFNβ treatment leads to shift from Th17 phenotype to Th1 phenotypes with upregulation of IFN-gamma in antigen-specific T cells in vivo. IFN-treated Th17 cells were able to inhibit EAE in vivo via adaptive transfer models. Together, our current findings demonstrate the direct effects of type I IFN on Th17 cells and reveal that Th cell plasticity is influenced by type I IFN during immune response.