Antitumor necrosis factor-α (TNF-α) is used for treatment of severe cases of inflammatory bowel diseases (IBD), including Crohn's disease (CD) and ulcerative colitis (UC). However, one-third of the patients do not respond to the treatment. Genetic markers may predict individual response to anti-TNF therapy. Using a candidate gene approach, 39 mainly functional single nucleotide polymorphisms (SNPs) in 26 genes regulating inflammation were assessed in 738 prior anti-TNF-naive Danish patients with IBD. The results were analyzed using logistic regression (crude and adjusted for age, gender and smoking status). Nineteen functional polymorphisms that alter the NFκB-mediated inflammatory response (TLR2 (rs3804099, rs11938228, rs1816702, rs4696480), TLR4 (rs5030728, rs1554973), TLR9 (rs187084, rs352139), LY96 (MD-2) (rs11465996), CD14 (rs2569190), MAP3K14 (NIK) (rs7222094)), TNF-α signaling (TNFA (TNF-α) (rs361525), TNFRSF1A (TNFR1) (rs4149570), TNFAIP3(A20) (rs6927172)) and other cytokines regulated by NFκB (IL1B (rs4848306), IL1RN (rs4251961), IL6 (rs10499563), IL17A (rs2275913), IFNG (rs2430561)) were associated with response to anti-TNF therapy among patients with CD, UC or both CD and UC (P ⩽ 0.05). In conclusion, the results suggest that polymorphisms in genes involved in activating NFκB through the Toll-like receptor (TLR) pathways, genes regulating TNF-α signaling and cytokines regulated by NFκB are important predictors for the response to anti-TNF therapy among patients with IBD. Genetically strong TNF-mediated inflammatory response was associated with beneficial response. In addition, the cytokines IL-1β, IL-6 and IFN-γ may be potential targets for treating patients with IBD who do not respond to anti-TNF therapy. These findings should be examined in independent cohorts before these results are applied in a clinical setting.

OBJECTIVE

In recent years, there has been an increasing understanding of the importance of the TH17 lineage of T cells and related cytokines, including interleukin (IL)17 and IL23, not only in the biology of innate host defense but also in the pathogenesis of inflammatory/autoimmune diseases. These diseases include psoriasis, psoriatic arthritis, the broader category of spondyloarthritides including ankylosing spondylitis and rheumatoid arthritis. It is postulated that in genetically predisposed individuals, external or internal stimuli such as microbial antigens, alterations in the intestinal microbiome, biomechanical stress and/or immunologic dysregulation may lead to an increased expression of cytokines such as IL23, which in turn stimulate the differentiation and activation of TH17 and other immune cells, which are a part of the innate immune system that trigger adaptive immune processes and chronic inflammatory diseases. Herein, we explore the effect of targeting this pathway therapeutically.

RESULTS

New drugs that are designed to inhibit steps in this pathway, the IL12/IL23 inhibitor, ustekinumab, the IL17A inhibitors secukinumab and ixekizumab, the IL17A receptor inhibitor, brodalumab, and the IL23 inhibitors guselkumab and tildrakizumab, have demonstrated significant effectiveness in treating these diseases, particularly psoriasis, psoriatic arthritis and ankylosing spondylitis.

CONCLUSIONS

This article reviews the relevant biology, efficacy and safety of new medications targeting the TH17 pathway, including inhibition of IL17 and IL23, particularly in psoriasis and psoriatic arthritis. Especially for patients who have not gained benefit from, lost effectiveness to or could not use antitumour necrosis factor (TNF) medications for safety or tolerability reasons, having effective medicines with an alternative mechanism of action will improve our ability to diminish disease activity impact on patient lives.

BACKGROUND

The IL23/IL17 pathway is pivotal in the development of chronic mucosal inflammation seen in Crohn's disease (CD). Genetic variants in the IL23R and IL12B have been associated with CD susceptibility. We investigated 10 genes within the IL23/IL17 pathway in a case-control study of 763 CD cases and 254 healthy controls.

METHODS

We identified a novel association in haplotypes in IL17A (empirical P = 0.02), IL17RA (P = 0.001), IL17RD (P = 0.001), IL12RB1 (P = 0.003), and IL12RB2 (P = 0.001) as well as confirming the association with IL12B variants (P = 0.003).

RESULTS

The cumulative risk for carrying an increased number of CD risk haplotypes from genes in this pathway rises to an odds ratio of 4.3 for carrying 5 risk haplotypes. We have previously demonstrated an association between this cohort and IL23R haplotypes. Pairwise analyses suggest that there is statistical interaction between variants in IL17A and IL23R (P = 0.047) and between variants in IL17RA and IL23R (P = 0.036). Furthermore, a significant association between CD and the widely replicated IL23R variants is only seen in the presence of IL17A or IL17RA variants.

CONCLUSIONS

These data support the investigation of pathways implicated in CD pathogenesis in order to identify further susceptibility genes and also suggest that important gene-gene interaction is present in CD susceptibility.(Inflamm Bowel Dis 2009).

Interleukin (IL) 12 and IL23 are two related heterodimeric cytokines produced by antigen-presenting cells. The balance between these two cytokines plays a crucial role in the control of Th1/Th17 responses and autoimmune inflammation. Most studies focused on their transcriptional regulation. Herein, we explored the role of the adenine and uridine-rich element (ARE)-binding protein tristetraprolin (TTP) in influencing mRNA stability of IL12p35, IL12/23p40, and IL23p19 subunits. LPS-stimulated bone marrow-derived dendritic cells (BMDCs) from TTP(-/-) mice produced normal levels of IL12/23p40. Production of IL12p70 was modestly increased in these conditions. In contrast, we observed a strong impact of TTP on IL23 production and IL23p19 mRNA stability through several AREs in the 3' untranslated region. TTP(-/-) mice spontaneously develop an inflammatory syndrome characterized by cachexia, myeloid hyperplasia, dermatitis, and erosive arthritis. We observed IL23p19 expression within skin lesions associated with exacerbated IL17A and IL22 production by infiltrating γδ T cells and draining lymph node CD4 T cells. We demonstrate that the clinical and immunological parameters associated with TTP deficiency were completely dependent on the IL23-IL17A axis. We conclude that tight control of IL23 mRNA stability by TTP is critical to avoid severe inflammation.

G-CSF, its receptor, and IL-17 receptor A (IL-17RA) are all required to maintain baseline neutrophil counts in mice. In this study, we tested whether IL-17F could compensate and maintain baseline neutrophil counts in the absence of IL-17A. Unlike the reduced neutrophil counts found in IL-17RA-deficient mice, neutrophil counts were mildly increased in IL-17A-deficient (Il17a(-/-)) animals. There was no evidence for infection or altered neutrophil function. Plasma G-CSF and IL-17F levels were elevated in Il17a(-/-) compared with wild-type mice. IL-17F was mainly produced in the spleen and mesenteric lymph nodes, but IL-23 was unaltered in Il17a(-/-) mice. Instead, Il17a(-/-) splenocytes differentiated with IL-6, TGF-beta, and IL-23 ex vivo produced significantly more IL-17F in response to IL-23 than wild-type cells. Adding rIL-17A to Il17a(-/-) splenocyte cultures reduced IL-17F mRNA and protein secretion. These effects were also observed in wild-type but not IL-17RA-deficient cells. We conclude that IL-17A mediated suppression of IL-17F production and secretion requires IL-17RA and is relevant to maintain the normal set point of blood neutrophil counts in vivo.

We recently characterized Winnie mice carrying a missense mutation in Muc2, leading to severe endoplasmic reticulum stress in intestinal goblet cells and spontaneous colitis. In this study, we characterized the immune responses due to this intestinal epithelial dysfunction. In Winnie, there was a fourfold increase in activated dendritic cells (DCs; CD11c(+) major histocompatibility complex (MHC) class II(hi)) in the colonic lamina propria accompanied by decreased colonic secretion of an inhibitor of DC activation, thymic stromal lymphopoietin (TSLP). Winnie also displayed a significant increase in mRNA expression of the mucosal T(H)17 signature genes Il17a, IL17f, Tgfb, and Ccr6, particularly in the distal colon. Winnie mesenteric lymph node leukocytes secreted multiple T(H)1, T(H)2, and T(H)17 cytokines on activation, with a large increase in interleukin-17A (IL-17A) progressively with age. A major source of mucosal IL-17A in Winnie was CD4(+) T lymphocytes. Loss of T and B lymphocytes in Rag1(-/-) × Winnie (RaW) crosses did not prevent spontaneous inflammation but did prevent progression with age in the colon but not the cecum. Adoptive transfer of naive T cells into RaW mice caused more rapid and severe colitis than in Rag1(-/-), indicating that the epithelial defect results in an intestinal microenvironment conducive to T-cell activation. Thus, the Winnie primary epithelial defect results in complex multicytokine-mediated colitis involving both innate and adaptive immune components with a prominent IL-23/T(H)17 response, similar to that of human ulcerative colitis.

Sjögren's syndrome (SS) involves a chronic, progressive inflammation primarily of the salivary and lacrimal glands leading to decreased levels of saliva and tears that eventually result in dry mouth and dry eye diseases. T(H)17 cell populations secreting IL17A have been shown to have an important function in an increasing number of autoimmune diseases, including SS. In this study, we investigated the function of IL17A on SS development and onset. Adenovirus-5 vectors expressing either IL17R:fragment of crystallization (Fc) fusion protein or LacZ were injected through retrograde cannulation into the salivary glands of SS-susceptible (SS(S)) C57BL/6.NOD-Aec1Aec2 mice between 6 and 8 weeks of age (a pre-disease stage) or 15 and 17 weeks of age (a diseased stage). The mice were subsequently characterized for their SS phenotypes. Mice cannulated with the Ad5-IL17R:Fc viral vector at either 7 or 16 weeks of age exhibited a rapid temporal, yet persistent, decrease in the levels of serum IL17 as well as the overall numbers of CD4+IL17+T cells present in their spleens. Disease profiling indicated that these mice showed decreased lymphocytic infiltrations of their salivary glands, normalization of their antinuclear antibodies repertoire, and increased saliva secretion. In contrast, mice cannulated with the control Ad5-LacZ viral vector did not exhibit similar changes and progressed to the overt disease stage. The capacity of the Ad5-IL17R:Fc-blocking factor to reduce SS pathology in SS(S) mice strongly suggests that IL17 is an important inflammatory cytokine in salivary gland dysfunction. Thus, therapeutic approach targeting IL17 may be effective in preventing glandular dysfunction.

BACKGROUND

End-stage chronic obstructive pulmonary disease (COPD) is associated with an accumulation of pulmonary lymphoid follicles. IL-17A is implicated in COPD and pulmonary lymphoid neogenesis in response to microbial stimuli. We hypothesized that IL-17A is increased in peripheral lung tissue during end-stage COPD and also directly contributes to cigarette smoke-induced lymphoid neogenesis.

OBJECTIVE

To characterize the tissue expression and functional role of IL-17A in end-stage COPD.

METHODS

Automated immune detection of IL-17A and IL-17F was performed in lung tissue specimens collected from patients with Global Initiative for Chronic Obstructive Lung Disease stage I-IV COPD, and smoking and never-smoking control subjects. In parallel, Il17a(-/-) mice and wild-type control animals were exposed to cigarette smoke for 24 weeks, and pulmonary lymphoid neogenesis was assessed.

RESULTS

Tissue expression of IL-17A and IL-17F was increased in COPD and correlated with lung function decline. IL-17A was significantly elevated in severe to very severe COPD (Global Initiative for Chronic Obstructive Lung Disease III/IV) compared with both smokers and never-smokers without COPD. Although CD3(+) T cells expressed IL-17A in very severe COPD, most IL-17A(+) cells were identified as tryptase-positive mast cells. Attenuated lymphoid neogenesis and reduced expression of the B-cell attracting chemokine C-X-C motif ligand (CXCL) 12 was observed in cigarette smoke-exposed Il17a(-/-) mice. CXCL12 was also highly expressed in lymphoid follicles in COPD lungs, and the pulmonary expression was significantly elevated in end-stage COPD.

CONCLUSIONS

IL-17A in the peripheral lung of patients with severe to very severe COPD may contribute to disease progression and development of lymphoid follicles via activation of CXCL12.

Transforming growth factor-β (TGF-β) has been shown to be required for Th17 cell differentiation via Smad-independent mechanisms. The molecular mechanism underlying this pathway remains to be clarified, however. We searched for genes regulated by TGF-β through the Smad-independent pathway by using Smad2 and Smad3 double-deficient T cells and identified the transcription factor Eomesodermin (Eomes), whose expression was suppressed by TGF-β via the c-Jun N-terminal kinase (JNK)-c-Jun signaling pathway. Inhibition of JNK strongly suppressed disease in an in vivo EAE model as well as in vitro Th17 cell induction. Overexpression of Eomes substantially suppressed Th17 cell differentiation, whereas ablation of Eomes expression could substitute for TGF-β in Th17 cell induction in primary T cells. Eomes suppressed Rorc and Il17a promoters by directly binding to the proximal region of these promoters. In conclusion, the suppression of Eomes by TGF-β via the JNK pathway is an important mechanism for Smad-independent Th17 cell differentiation.

Appropriate expression of IL-2 plays a central role during the priming and differentiation of T cells. A tight balance between IL-2 and the effector cytokine IL-17A is essential for immune homeostasis. Epigenetic mechanisms have been documented as a key component of cytokine regulation during lineage commitment. The molecular mechanisms that induce chromatin remodeling are less well understood. We investigated epigenetic regulators that mediate the diametric expression of IL-2 and IL-17A in naive, central memory, and effector memory CD4(+) T cells. We demonstrate that cAMP response modulator (CREM)α contributes to epigenetic remodeling of IL2 in effector memory T cells through the recruitment of DNMT3a. CREMα also reduces CpG-DNA methylation of the IL17A promoter. CREMα expression is regulated at the epigenetic level by CpG-DNA methylation, which allows increased CREMα expression in effector memory CD4(+) T cells. T cells from patients with systemic lupus erythematosus (SLE) express increased levels of CREMα and exhibit a phenotype that is similar to effector memory CD4(+) T cells with epigenetically predetermined expression patterns of IL-2 and IL-17A. We conclude that CREMα mediates epigenetic remodeling of the IL2 and IL17A gene during T-cell differentiation in favor of effector memory T cells in health and disease.

The aggressiveness of invasive ductal carcinoma (IDC) of the breast is associated with increased IL17 levels. Studying the role of IL17 in invasive breast tumor pathogenesis, we found that metastatic primary tumor-infiltrating T lymphocytes produced elevated levels of IL17, whereas IL17 neutralization inhibited tumor growth and prevented the migration of neutrophils and tumor cells to secondary disease sites. Tumorigenic neutrophils promote disease progression, producing CXCL1, MMP9, VEGF, and TNFα, and their depletion suppressed tumor growth. IL17A also induced IL6 and CCL20 production in metastatic tumor cells, favoring the recruitment and differentiation of Th17. In addition, IL17A changed the gene-expression profile and the behavior of nonmetastatic tumor cells, causing tumor growth in vivo, confirming the protumor role of IL17. Furthermore, high IL17 expression was associated with lower disease-free survival and worse prognosis in IDC patients. Thus, IL17 blockade represents an attractive approach for the control of invasive breast tumors.

CD44 is expressed by a variety of cells, including glial and T cells. Furthermore, in the demyelinating lesions of multiple sclerosis, CD44 expression is chronically elevated. In this study, we demonstrate that targeted deletion of CD44 attenuated myelin oligodendrocyte glycoprotein peptide-induced experimental autoimmune encephalitomyelitis (EAE) through novel regulatory mechanisms affecting Th differentiation. Specifically, by developing chimeras and using adoptive transfer experiments, we noted that CD44 deficiency on CD4(+) T cells, but not other cells, conferred protection against EAE induction. CD44 expression played a crucial role in Th differentiation, inasmuch as deletion of CD44 inhibited Th1/Th17 differentiation while simultaneously enhancing Th2/regulatory T cell differentiation. In contrast, expression of CD44 promoted Th1/Th17 differentiation. When osteopontin and hyaluronic acid, the two major ligands of CD44, were tested for their role in Th differentiation, osteopontin, but not hyaluronic acid, promoted Th1/Th17 differentiation. Furthermore, activation of CD44(+) encephalitogenic T cells with myelin oligodendrocyte glycoprotein peptide led to demethylation at the ifnγ/il17a promoter region while displaying hypermethylation at the il4/foxp3 gene promoter. Interestingly, similar activation of CD44-deficient encephalitogenic T cells led to increased hypermethylation of ifnγ/il17a gene and marked demethylation of il4/foxp3 gene promoter. Together, these data suggested that signaling through CD44, in encephalitogenic T cells, plays a crucial role in the differentiation of Th cells through epigenetic regulation, specifically DNA methylation of Th1/Th17 and Th2 cytokine genes. The current study also suggests that molecular targeting of CD44 receptor to promote a switch from Th1/Th17 to Th2/regulatory T cell differentiation may provide a novel treatment modality against EAE.

Interleukin 10 receptor (IL10R)-deficient mice develop spontaneous colitis and, similarly, patients with loss-of-function mutations in IL10R develop severe infant-onset inflammatory bowel disease. Loss of IL10R signaling in mouse and human macrophages is associated with increased production of interleukin 1β. We demonstrated that innate immune production of IL1β mediates colitis in IL10R-deficient mice. Transfer of Il1r1-/- CD4+ T cells into Rag1-/-/Il10rb-/- mice reduced the severity of their colitis (compared to mice that received CD4+ T cells that express IL1R), accompanied by decreased production of interferon gamma, tumor necrosis factor-α, and IL17A. In macrophages from mice without disruption of IL10R signaling or from healthy humans (controls), incubation with IL10 reduced canonical activation of the inflammasome and production of IL1β through transcriptional and post-translational regulation of NLRP3. Lipopolysaccharide and adenosine triphosphate stimulation of macrophages from Il10rb-/- mice or IL10R-deficient patients resulted in increased production of IL1β. Moreover, in human IL10R-deficient macrophages, lipopolysaccharide stimulation alone triggered IL1β secretion via non-canonical, caspase 8-dependent activation of the inflammasome. We treated 2 IL10R-deficient patients with severe and treatment-refractory infant-onset inflammatory bowel disease with the IL1-receptor antagonist anakinra. Both patients had marked clinical, endoscopic, and histologic responses after 4-7 weeks. This treatment served as successful bridge to allogeneic hematopoietic stem cell transplantation in 1 patient. Our findings indicate that loss of IL10 signaling leads to intestinal inflammation, at least in part, through increased production of IL1 by innate immune cells, leading to activation of CD4+ T cells. Agents that block IL1 signaling might be used to treat patients with inflammatory bowel disease resulting from IL10R deficiency.

The epidermis, the outer layer of the skin, forms a physical and antimicrobial shield to protect the body from environmental threats. Skin injury severely compromises the epidermal barrier and requires immediate repair. Dendritic epidermal T cells (DETC) reside in the murine epidermis where they sense skin injury and serve as regulators and orchestrators of immune responses. Here, we determined that TCR stimulation and skin injury induces IL-17A production by a subset of DETC. This subset of IL-17A-producing DETC was distinct from IFN-γ producers, despite similar surface marker profiles. Functionally, blocking IL-17A or genetic deletion of IL-17A resulted in delayed wound closure in animals. Skin organ cultures from Tcrd-/-, which lack DETC, and Il17a-/- mice both exhibited wound-healing defects. Wound healing was fully restored by the addition of WT DETC, but only partially restored by IL-17A-deficient DETC, demonstrating the importance of IL-17A to wound healing. Following skin injury, DETC-derived IL-17A induced expression of multiple host-defense molecules in epidermal keratinocytes to promote healing. Together, these data provide a mechanistic link between IL-17A production by DETC, host-defense, and wound-healing responses in the skin. These findings establish a critical and unique role of IL-17A-producing DETC in epidermal barrier function and wound healing.

IL-17-producing CD4(+)Th17 cells, CD8(+)Tc17 cells, and γδ T cells play critical roles in the pathogenesis of autoimmune psoriasis. RORγt is required for the differentiation of Th17 cells and expression of IL-17. In this article, we describe a novel, potent, and selective RORγt inverse agonist (TMP778), and its inactive diastereomer (TMP776). This chemistry, for the first time to our knowledge, provides a unique and powerful set of tools to probe RORγt-dependent functions. TMP778, but not TMP776, blocked human Th17 and Tc17 cell differentiation and also acutely modulated IL-17A production and inflammatory Th17-signature gene expression (Il17a, Il17f, Il22, Il26, Ccr6, and Il23) in mature human Th17 effector/memory T cells. In addition, TMP778, but not TMP776, inhibited IL-17A production in both human and mouse γδ T cells. IL-23-induced IL-17A production was also blocked by TMP778 treatment. In vivo targeting of RORγt in mice via TMP778 administration reduced imiquimod-induced psoriasis-like cutaneous inflammation. Further, TMP778 selectively regulated Th17-signature gene expression in mononuclear cells isolated from both the blood and affected skin of psoriasis patients. In summary, to our knowledge, we are the first to demonstrate that RORγt inverse agonists: 1) inhibit Tc17 cell differentiation, as well as IL-17 production by γδ T cells and CD8(+) Tc17 cells; 2) block imiquimod-induced cutaneous inflammation; 3) inhibit Th17 signature gene expression by cells isolated from psoriatic patient samples; and 4) block IL-23-induced IL-17A expression. Thus, RORγt is a tractable drug target for the treatment of cutaneous inflammatory disorders, which may afford additional therapeutic benefit over existing modalities that target only IL-17A.

Staphylococcus aureus is a prolific mastitis-causing bacterium that resides naturally in the environment of the dairy cow. The aim of this study was to profile immune gene expression in tissue from the alveolar, ductal, gland cistern and teat canal regions of the bovine mammary gland following intramammary infection with S. aureus. Quantitative real-time PCR (qPCR) was used to profile expression of innate immune genes including pattern recognition receptors (PRRs), cytokines, antimicrobial peptides (AMPs) and acute phase proteins (APPs). Consistent expression of Toll-like receptors (TLRs) 1-10 and NOD-like receptors (NODs) 1-2 was detected in all four tissue regions. Pro-inflammatory cytokines (IL6, IL17A and IL8) and anti-inflammatory cytokine (IL10) were induced in all 4 tissues. APP (SAA3 and HP) and AMP (DEFB4 and DEFB5) genes showed the greatest induction throughout the mammary gland in response to S. aureus, with particularly high expression in alveolar tissue (SAA3 and HP >133- and >80-fold respectively, P<0.05; DEFB4 and DEFB5 >9- and >27-fold respectively, P<0.05). Collectively, our data show both sentinel and effector immune functions throughout the mammary gland in response to S. aureus challenge.

OBJECTIVE

Most asthmatic patients have well controlled symptoms with regular treatment, but some require much higher doses of inhaled and oral corticosteroids, or in rare cases fail to respond; these patients may present Th-17 cell infiltration and associated cytokines (IL-17A and -F) in the airways, sputum and peripheral blood. Because glucocorticoid receptor-beta (GR-beta) is associated with corticosteroid resistance, we investigated whether Th-17 associated cytokines induce steroid insensitivity in PBMCs via GR-beta up-regulation.

METHODS

GR-alpha, GR-beta, GILZ and IL-6 expression were analyzed in PBMCs stimulated with IL-2/IL-4, IL-17A/IL-17F and IL-23 cytokines by quantitative RT-PCR. Dexamethasone-inhibition of PHA-induced proliferation and Dexamethasone-induced apoptosis were determined by either (3)H-thymidine or CFSE-labelled cells and by Annexin-V staining and flow cytometry.

RESULTS

IL-17 and IL-23 cytokines significantly increased GR-beta expression. IL-2/IL-4 significantly decreased GR-alpha expression without affecting GR-beta. IL17, IL-23 and IL2 + 4 stimulations significantly hampered Dexamethasone-inhibition of proliferation (Dex EC(50) for: IL-17A + F = 251 nM; IL-23 = 435 nM; IL2 + 4 = 950 nM; Medium = 90 nM). IL2 + 4 and IL17A + F but not IL-23, significantly hampered Dexamethasone-induced apoptosis (1400 and 320 nM Dex, respectively). Dexamethasone's trans-activation of GILZ and trans-repression of NF-kB-driven IL-6 expression were both inhibited by IL2 + 4; IL17 + IL23 antagonized Dex trans-repression in PBMC from asthmatics.

CONCLUSIONS

GR-beta up-regulation by IL-17/IL-23 cytokines is associated with induced steroid insensitivity in PBMCs, observed as diminished Dexamethasone's effects on cell proliferation, apoptosis and gene regulation. Steroid resistance induced by IL-2/IL-4 was associated with decreased GR-alpha expression. This study supports the possibility that Th-17 lymphocytes and associated cytokines play a role in the mechanism of steroid hypo-responsiveness in severe asthmatics.

OBJECTIVE

Emerging data on the gut microbiome in autism spectrum disorder (ASD) suggest that altered host-microbe interactions may contribute to disease symptoms. Although gut microbial communities in children with ASD are reported to differ from individuals with neurotypical development, it is not known whether these bacteria induce pathogenic neuroimmune signals.

METHODS

Because commensal clostridia interactions with the intestinal mucosa can regulate disease-associated cytokine and serotonergic pathways in animal models, we evaluated whether microbiome-neuroimmune profiles (from rectal biopsy specimens and blood) differed in ASD children with functional gastrointestinal disorders (ASD-FGID, n = 14) compared with neurotypical (NT) children with FGID (NT-FGID, n = 15) and without abdominal pain (NT, n = 6). Microbial 16S ribosomal DNA community signatures, cytokines, and serotonergic metabolites were quantified and correlated with gastrointestinal symptoms.

RESULTS

A significant increase in several mucosa-associated Clostridiales was observed in ASD-FGID, whereas marked decreases in Dorea and Blautia, as well as Sutterella, were evident. Stratification by abdominal pain showed multiple organisms in ASD-FGID that correlated significantly with cytokines (interleukin [IL]6, IL1, IL17A, and interferon-γ). Group comparisons showed that IL6 and tryptophan release by mucosal biopsy specimens was highest in ASD children with abdominal pain, whereas serotonergic metabolites generally were increased in children with FGIDs. Furthermore, proinflammatory cytokines correlated significantly with several Clostridiales previously reported to associate with ASD, as did tryptophan and serotonin.

CONCLUSIONS

Our findings identify distinctive mucosal microbial signatures in ASD children with FGID that correlate with cytokine and tryptophan homeostasis. Future studies are needed to establish whether these disease-associated Clostridiales species confer early pathogenic signals in children with ASD and FGID.

Study of the development of distinct CD4(+) T-cell subsets from naive precursors continues to provide excellent opportunities for dissection of mechanisms that control lineage-specific gene expression or repression. Whereas it had been thought that the induction of transcription networks that control T-lineage commitment were highly stable, reinforced by epigenetic processes that confer heritability of functional phenotypes by the progeny of mature T cells, recent findings support a more dynamic view of T-lineage commitment. Here, we highlight advances in the mapping and functional characterization of cis elements in the Ifng locus that have provided new insights into the control of the chromatin structure and transcriptional activity of this signature T-helper 1 cell gene. We also examine epigenetic features of the Ifng locus that have evolved to enable its reprogramming for expression by other T-cell subsets, particularly T-helper 17 cells, and contrast features of the Ifng locus with those of the Il17a-Il17f locus, which appears less promiscuous.

Systemic lupus erythematosus (SLE) is an autoimmune disease accompanied by disturbed T-cell homeostasis. Dysbalance of T-helper-cell (Th) subsets (Th1/Th2/Th17) and regulatory T-cells (T(regs)) is suggested to contribute to the pathogenesis of SLE. Recent reports suggest functional deviation of T(regs) in terms of producing IL-17A, a process that may be aberrant in SLE. Therefore, we analyzed these T-cell subsets in SLE to test the hypothesis that aberrant T-cell subset skewing is present in SLE-patients. We investigated simultaneously the intracellular cytokines IFN-γ, IL-4 and IL-17A in CD4(+)T-cells as well as in T(regs). Skewing of T-cell subsets towards Th17 cells was observed in SLE-patients. Although the proportion of T(regs) was similar between SLE-patients and healthy controls, the ability of T(regs) to express IFN-γ and IL17A was impaired in SLE-patients. Even in quiescent SLE-patients T-cell homeostasis is aberrant in terms of skewing towards IL-17 producing T-cells.

BACKGROUND

Nontypeable Haemophilus influenzae (NTHi) causes acute exacerbation of chronic obstructive pulmonary disease (AECOPD). IL-17A is central for neutrophilic inflammation and has been linked to COPD pathogenesis.

OBJECTIVE

We investigated whether IL-17A is elevated in NTHi-associated AECOPD and required for NTHi-exacerbated pulmonary neutrophilia induced by cigarette smoke.

METHODS

Experimental studies with cigarette smoke and NTHi infection were pursued in gene-targeted mice and using antibody intervention. IL-17A was measured in sputum collected from patients with COPD at baseline, during, and after AECOPD.

RESULTS

Exacerbated airway neutrophilia in cigarette smoke-exposed mice infected with NTHi was associated with an induction of IL-17A. In agreement, elevated IL-17A was observed in sputum collected during NTHi-associated AECOPD, compared with samples collected before or after the event. NTHi-exacerbated neutrophilia and induction of neutrophil chemoattractants over the background of cigarette smoke, as observed in wild-type mice, was absent in Il17a(-/-) mice and in mice treated with a neutralizing anti-IL-17A antibody. Further studies revealed that IL-1 receptor (R)1 signaling was required for IL-17A-dependent neutrophilia. Moreover, deficiency or therapeutic neutralization of IL-17A did not increase bacterial burden or delay bacterial clearance.

CONCLUSIONS

IL-17A is induced during NTHi-associated AECOPD. Functionally, IL-1R1-dependent IL-17A is required for NTHi-exacerbated pulmonary neutrophilia induced by cigarette smoke. Targeting IL-17A in AECOPD may thus be beneficial to reduce neutrophil recruitment to the airways.

We recently found that activation of IL17A signaling promotes the development and progression of acute and chronic pulmonary fibrosis, and that the blockade of IL17A activity attenuates pulmonary fibrosis by promoting the resolution of inflammation and the activation of autophagy. Although the induction of autophagy stimulating the collagen degradation in the fibrotic lung tissue has been identified as a mechanism responsible for the antifibrotic role of targeting IL17A, it remains to be clarified how IL17A signaling suppresses autophagy. Here we report that the phosphorylation of B-cell CLL/lymphoma 2 (BCL2), an apoptosis regulatory protein, was inhibited in the presence of IL17A in lung epithelial cells, and this reduction suppressed the ubiquitination degradation of BCL2, which subsequently attenuated autophagy by promoting the interaction of BCL2 and BECN1. We found that IL17A regulated the phosphorylation of BCL2 through activating the phosphoinositide 3-kinase (PI3K)-glycogen synthase kinase 3 β (GSK3B) signaling cascade. In response to IL17A stimulation, PI3K was activated and resulted in phosphorylation of GSK3B at Ser9, which subsequently attenuated the interaction of GSK3B with BCL2. Interrupting the GSK3B and BCL2 interaction precluded the phosphorylation of BCL2 at Ser70, which could trigger the ubiquitination degradation, and restrained the ubiquitination degradation of BCL2. Consequently, a decrease in the BCL2 degradation induced by IL17A resulted in a suppressed autophagy in lung epithelial cells. These findings indicate that the IL17A-PI3K-GSK3B-BCL2 signaling pathway participates in the attenuation of autophagic activity in lung epithelial cells, which is attributed to be primarily responsible for the development and progression of IL17A-induced pulmonary fibrosis.

Interleukin-17 (IL-17) is a proinflammatory cytokine that is associated with inflammation, autoimmune disorders, and even tumors. Previous studies revealed that a large group of human malignant tumors have abnormally high IL-17 expression. In the present study, we analyzed two single-nucleotide polymorphisms (SNPs) in the IL17A (rs2275913) and IL17F (rs763780) in 311 cervical cancer patients and 463 controls using TaqMan assays. Our results indicated that the frequencies of AA genotype and A allele of rs2275913 were significantly different between the cervical cancer patients and controls (P = 0.008, OR = 1.32, 95% CI, 1.07-1.62). Stratified analyses revealed that the polymorphism of rs2275913 was also associated with positive peritumor intravascular cancer emboli and high clinical stage. The genotype and allele frequencies of rs763780 did not show any difference between patients and controls or relate to patient clinical characteristics. Collectively, these findings suggested that IL17 gene polymorphism rs2275913 was associated with the susceptibility as well as positive peritumor intravascular cancer emboli and high clinical stage of cervical cancer in Chinese women.

High mobility group box 1 (HMGB1)-Toll-like receptor 4 (TLR4) signaling has been recently found to induce interleukin (IL)-17A secretion in drug-induced hepatitis and myocardial I/R injury. The purpose of this study is to evaluate whether HMGB1-TLR4 signaling could induce IL-17A secretion and lead to brain I/R injury. We also sought to investigate whether glycyrrhizin elucidated its neuroprotective effects through HMGB1-TLR4-IL-17A signaling pathway. Various biochemical estimations, neurological status, and assessment of cerebral infarct size were carried out 72h after middle cerebral artery occlusion (MCAO) stroke. Apoptotic cells were assessed using a terminal deoxynucleotidyl transferase, dUTP nick and labeling (TUNEL) kit. The expression of HMGB1, IL-17A, bcl-2, bax and cleaved caspase-3, were determined by Western blot assay. In the present study we found that glycyrrhizin significantly decreased HMGB1 protein expression. Glycyrrhizin markedly reduced whereas recombinant HMGB1 (rHMGB1) increased IL-17A expression. HMGB1 induced increase of IL-17A was significantly diminished in TLR4-mutant C3H/HeJ mice. Brain injury and neurological deficits were largely abrogated by glycyrrhizin or IL-17A knockout. In contrast, rHMGB1 or recombinant mouse IL-17A markedly increased I/R injury. However, rHMGB1 had no effects on infarct size and neurological deficits in Il17a(-/-) mice following brain I/R injury. In addition, IL-17A knockout mice significantly increased bcl-2 protein expression and had fewer apoptotic cells, whereas recombinant IL-17A-treated mice significantly increased bax and cleaved caspase-3 protein expression and had more apoptotic cells. Together these results indicate that glycyrrhizin has neuroprotective efficacy in the postischemic brain through HMGB1-TLR4-IL-17A signaling pathway.