Th17 cytokines in inflammatory bowel diseases: discerning the good from the bad

Immune-mediated inflammatory diseases: Common and different pathogenic and clinical features

The term "immune-mediated inflammatory diseases (IMIDs)" refers to several inflammatory pathologies of multifactorial etiology and involving either simultaneously or sequentially more organs. IMIDs share some common pathogenic mechanisms, which account for some similarities in the clinical course and the impact that these diseases may have on other organs and systems of the body. However, there are some differences in the IMID-associated pathological process, including the synthesis and function of multiple inflammatory cytokines, which are supposed to perpetuate the tissue-damaging inflammation. This justifies the different indications and responsiveness to corticosteroids, immunosuppressors, small molecules, and biologics. Many individuals with IMIDs are, however, intolerant, or unresponsive to the current drugs, thus suggesting the necessity of novel therapeutic approaches, such as the combination of compounds that either inhibit more immuno-inflammatory networks selectively or simultaneously suppress inflammatory signals and activate counter-regulatory pathways. In this article, we highlight the most relevant features of IMIDs and discuss how clinicians can combat the detrimental immune response in such disorders.

Interleukin-34 Mediates Cross-Talk Between Stromal Cells and Immune Cells in the Gut

Initially known as a cytokine produced by and regulating the function of monocytes and macrophages, interleukin-34 (IL-34) can be synthesized by many cell types and interacts with receptors expressed by multiple immune and non-immune cells. IL-34 is constitutively expressed in the healthy human small intestine and colon and its production is markedly increased in damaged gut of patients with Crohn’s disease and patients with ulcerative colitis, the main forms of chronic inflammatory bowel diseases (IBD) in human beings. Circumstantial evidence suggests that, in these pathologies, IL-34 plays a crucial role in mediating cross-talk between immune cells and stromal cells, thereby promoting activation of signalling pathways, which amplify the ongoing mucosal inflammation as well as production of fibrogenic molecules. In this article, we summarize the available data supporting the multiple effects of IL-34 in human IBD with particular attention to the role of the cytokine in immune and stromal cell interactions.

Novel Therapeutic Options for People with Ulcerative Colitis: An Update on Recent Developments with Janus Kinase (JAK) Inhibitors

Crohn’s disease (CD) and ulcerative colitis (UC), the main forms of inflammatory bowel disease (IBD) in human beings, are chronic relapsing-remitting disorders of the gastrointestinal tract, which usually require lifelong therapies. For many years, IBD have been managed with corticosteroids, aminosalicylates and immunosuppressants (ie, thiopurines). The advent of biologic therapies (anti-TNF-α agents) has significantly improved the outcome of IBD patients in terms of prolonged clinical remission, corticosteroid sparing, achievement of mucosal healing and prevention of disease-related complications. Nevertheless, primary failure or loss of response to biologics occur in about 50% of patients treated with these drugs. Therefore, the need for new effective treatments for such patients has critically emerged as an urgent priority. With this regard, several small-molecule drugs (SMDs) targeting lymphocyte trafficking (ie, sphingosine-1-phosphate receptor modulators) and the JAK/STAT pathway (eg, tofacitinib) have been recently developed and tested in IBD. In particular, JAK inhibitors are oral compounds characterized by short half-life, low antigenicity and the ability to dampen several pro-inflammatory pathways simultaneously. Tofacitinib, a pan-JAK inhibitor, has shown good efficacy and safety in UC clinical trials and has been recently approved for the treatment of UC patients. In this review, we analyze the main evidence supporting the use of JAK inhibitors in UC and explore the unanswered questions about the use of this class of drug in UC.

Type 3 cytokines in liver fibrosis and liver cancer

The type 3 cytokines IL-17 and IL-22 play a crucial, well synchronized physiological role in wound healing and repairing tissue damage due to infections or injury at barrier surfaces. These cytokines act on epithelial cells to induce secretion of early immune mediators, recruitment of inflammatory cells to the site of injury, and to trigger tissue repair mechanisms. However, if the damage persists or if these cytokines are dysregulated, then they contribute to a number of inflammatory pathologies, autoimmune conditions and cancer. The liver is a multifunctional organ that plays an essential role in metabolism, detoxification, and immune surveillance. It is also exposed to a variety of pathogens, toxins and injuries. Over the past decade, IL-17 and IL-22 have been implicated in various aspects of liver inflammation. IL-17 is upregulated in chronic liver injury and associated with liver disease progression. In contrast, IL-22 was shown to be hepatoprotective during acute liver injury but exhibited inflammatory effects in other models. Furthermore, IL-22 and IL-17 are both associated with poor prognosis in liver cancer. Finally, the regulatory mechanisms governing the physiological versus the pathological role of these two cytokines during acute and chronic liver injury remain poorly understood. In this review, we will summarize the current state of knowledge about IL-17 and IL-22 in wound healing during acute and chronic liver injury, their contribution to pathogenesis, their regulation, and their role in the transition from advanced liver disease to liver cancer.

Paradoxical role of Breg-inducing cytokines in autoimmune diseases

Regulatory B cells (Breg) are crucial immunoregulators that maintain peripheral tolerance and suppress inflammatory autoimmune responses. In recent years, our understanding on the nature and mechanism of action of Bregs has revealed the important role of cytokines in promoting the regulatory properties of this unique B cell subset, both in animal and human models. In this review, we compiled the cytokines that have been reported by multiple studies to induce the expansion of Breg. The Breg-inducing cytokines which are currently known include IL-21, IL-6, IL1β, IFNα, IL-33, IL-35, BAFF and APRIL. As cytokines are also known to play a pivotal role in the pathogenesis of autoimmune diseases, in parallel we reviewed the pattern of expression of the Breg-inducing cytokines in Systemic Lupus Erythematosus (SLE), Rheumatoid Arthritis (RA), Inflammatory Bowel Diseases (IBD) and Multiple Sclerosis (MS). We show here that Breg-inducing cytokines are commonly implicated in these inflammatory diseases where they typically have a higher expression than in healthy individuals, suggesting their paradoxical nature. Interestingly, despite the general overexpression of Breg-inducing cytokines, it is known that Breg cells are often numerically or functionally impaired in various autoimmune conditions. Considering these alterations, we explored the possible parameters that may influence the function of Breg-inducing cytokines in exhibiting either their regulatory or pro-inflammatory properties in the context of autoimmune conditions.

The Effect of IL-26 on TNF-α-Induced CXCL8 Responses by Colonic Epithelial Cell Lines

Th17 cells of the intestine and colon can produce several important cytokines during mucosal inflammation. However, few studies have focused on the role of IL-26 in intestinal inflammations. Colonic epithelial cells express receptors for IL-26, and this cytokine has been shown to induce the HT-29 colonic epithelial cell line to produce the chemokine CXCL8. However, epithelial cells would function in a cytokine network environment during mucosal inflammation and any effect of IL-26 on colonic epithelial cell chemokine responses could be affected by the presence of other potent pro-inflammatory cytokines like TNF-α and IL-1. Therefore, we investigated the effect of IL-26 with TNF-α or IL-1 on colonic epithelial cell line secretion of CXCL8. IL-26 alone had no effect on HT-29 or DLD1 cell line CXCL8 secretion. Yet, IL-26 was found to significantly enhance TNF-α-induced, but not IL-1-induced, CXCL8 secretion, but only at high levels of TNF-α. Similar results were seen with DLD1 cells. IL-26 did not enhance TNF-α-induced CXCL8 mRNA levels and did not affect TNF-α-induced IκBα phosphorylation or degradation. However, signaling through ERK and p38 MAPK were determined to be involved in the enhancing effect of IL-26 on the TNF-α-induced CXCL8 secretion, perhaps through known post-translational effects. These results suggest that the role of IL-26 in intestinal inflammation may be limited to enhancing CXCL8 secretion in the presence high levels of TNF-α, such as may occur in inflammatory bowel disease. Abbreviations: DMEM, Dulbecco's Modified Eagle's Medium; GAPDH, glyceraldehyde-3-phosphate dehydrogenase; IBD, inflammatory bowel disease; IL, interleukin; ITS, insulin, transferrin, selenium; TBS, Tris buffered saline; TNF, tumor necrosis factor.

T-cell Composition in Ileal and Colonic Creeping Fat - Separating Ileal from Colonic Crohn's Disease

BACKGROUND AND AIMS

Creeping fat [CF] is a hyperplasia of adipose tissue adjacent to inflamed intestine in Crohn's disease [CD]. Data from genome-wide association studies [GWAS] distinguished Crohn's colitis from ileal CD and ulcerative colitis [UC]. This study analysed the T-cell compartments of ileal and colonic mesenteric fat and corresponding mucosa to provide cellular proof for the suggested GWAS classification.

METHODS

Samples were obtained from 34 CD or UC patients. Cells were analysed by immunohistochemistry and flow cytometry, and tissue cytokine release was assessed by cytometric bead array.

RESULTS

Only ileal CF revealed the distinct adipocyte hyperplasia combined with dense T-cell infiltration and fibrosis; colonic fat from CD and UC patients lacked these findings. T-cell subpopulations differed between mesenteric fat in ileal CD, colonic CD and UC: ileal CF had nearly 10 times more T-cells than colonic fat. The proportions of regulatory and central memory T-cells were significantly higher in ileal CF compared with colonic fat in CD and UC. In all groups, the mucosal T-cell compartment was distinct from the mesenteric fat. Remarkably, correlation between disease activity and proportion of pro- and anti-inflammatory T-cell subpopulations was inverse, comparing ileal and colonic fat in CD.

CONCLUSIONS

This first in-depth analysis of the T-cell compartment in ileal and colonic mesenteric adipose tissue in CD and UC identifies a unique T-cell niche in the ileal mesenteric fat tissue in CD. From a clinical point of view, our findings underscore the novel concept of colonic and ileal CD as distinct IBD entities.

MicroRNA‑146a inhibits the inflammatory responses induced by interleukin‑17A during the infection of Helicobacter pylori

Helicobacter pylori (H. pylori) infection is the major cause of chronic active gastritis and peptic ulcer disease. Upregulation of IL‑17A is associated with H. pylori infection in the gastric mucosa; however, the factors involved in the regulation of interleukin (IL)‑17A‑induced inflammatory responses in H. pylori‑associated gastritis remain unknown. MicroRNAs (miRNAs) serve as key post‑transcriptional regulators of gene expression and are associated with the H. pylori infection. The present study aimed to analyze the effects of IL‑17A on the expression of miR‑146a upon infection with H. pylori, as well as to identify the possible impact of miR‑146a dysregulation on the inflammatory response in vivo and in vitro. Reverse transcription‑quantitative polymerase chain reaction analysis was used to determine the expression levels of miR‑146a in gastric epithelial cells upon IL‑17A stimulation. The effects of miR‑146a mimics on IL‑17A‑induced inflammatory responses in SGC‑7901 cells were evaluated. The effects of miR‑146a mimics on the expression levels of IL‑1 receptor‑associated kinase 1 (IRAK1) and tumor necrosis factor receptor‑associated factor 6 (TRAF6) upon IL‑17A treatment were analyzed, and the IL‑17A‑stimulated inflammation following the silencing of IRAK1 and TRAF6 was observed. In addition, the correlation between miR‑146a and IL‑17A in human gastric mucosa with H. pylori was examined. The results indicated that IL‑17A‑induced miR‑146a may regulate the inflammatory response during the infection of H. pylori in a nuclear factor‑κB‑dependent manner. Furthermore, the expression of miR‑146a and IL‑17A are positively correlated in human gastric mucosa infected with H. pylori. These data suggested that miR‑146a may serve as a biomarker or therapeutic target in gastritis therapy.

MiRNAs and inflammatory bowel disease: An interesting new story

Inflammatory bowel disease (IBD), as a chronic and recurrent inflammatory disorder, is caused by a dysregulated and aberrant immune response to exposed environmental factors in genetically susceptible individuals. Despite huge efforts in determining the molecular pathogenesis of IBD, an increasing worldwide incidence of IBD has been reported. MicroRNAs (miRNAs) are a set of noncoding RNA molecules that are about 22 nucleotides long, and these molecules are involved in the regulation of the gene expression. By clarifying the important role of miRNAs in a number of diseases, their role was also considered in IBD; numerous studies have been performed on this topic. In this review, we attempt to summarize a number of studies and discuss some of the recent developments in the roles of miRNAs in the pathophysiology, diagnosis, and treatment of IBD.

Evaluating IL-21 as a Potential Therapeutic Target in Crohn's Disease

Background and Aim

Interleukin-21 (IL-21) is primarily a T cell-derived cytokine; it is upregulated in patients with Crohn's Disease (CD) and could be a potential new therapeutic target in CD.

Methods

In human material, IL-21 and IL-21R expression was investigated by in situ hybridization (ISH) and immunohistochemistry (IHC) in noninflammatory bowel disease (non-IBD) controls and patients with CD. The pathologic role of IL-21 was examined in murine models of T cell-dependent and T cell-independent colitis, either with a neutralizing monoclonal antibody against IL-21 or with the transfer of CD4⁺CD45RB^highIL-21R^-/- T cells. Colonic pathology was examined by endoscopy, histopathology, IHC, ELISA, and Luminex.

Results

In the human intestine, IL-21 and IL-21R mRNA and protein-expressing cells were observed in the mucosa, in lymphoid aggregates of submucosa in non-IBD controls, and in lymphoid aggregates of muscularis externa in patients with CD. IL-21 expression was most abundant in germinal centers (GCs) of the lymphoid aggregates, and IL-21R expression assessed semiquantitatively, was significantly higher in patients with CD compared to non-IBD controls. Following prophylactic and interventive anti-IL-21 mAb treatment in the adoptive transfer (AdTr) model, clinical and pathological parameters were significantly reduced. The most persistent finding was a reduction in colonic infiltrating neutrophils. As well, Rag2^-/- mice receiving CD4⁺CD45RB^highIL-21R^-/- T cells developed less severe colitis compared to Rag2^-/- mice receiving CD4⁺CD45RB^highIL-21R^+/+ T cells. No effect of reduced IL-21 signalling was observed in T cell-independent colitis.

Conclusion

Our study shows that patients with CD have significant expression of IL-21 and IL-21R in the gut. As well, we show that neutralization of IL-21 in experimental T cell-driven colitis is associated with a reduction in clinical and pathological findings. This amelioration seems to be associated with a reduction in colon-infiltrating neutrophils.

Retinoic Acid Improves Incidence and Severity of Necrotizing Enterocolitis by Lymphocyte Balance Restitution and Repopulation of LGR5+ Intestinal Stem Cells

Necrotizing enterocolitis (NEC) is the most devastating gastrointestinal disease of the premature infant. We have recently shown that NEC development occurs after an increase in proinflammatory CD4Th17 (Th17) cells and reduced anti-inflammatory forkhead box P3 regulatory T cells (Tregs) to the premature small intestine of mice and humans, which can be experimentally reversed in mice by administration of all-trans retinoic acid (ATRA). We have also shown that NEC is characterized by apoptosis of Lgr5-positive intestinal stem cells (ISCs-Lgr5 cells) within the crypts of Lieberkühn, which are subsequently essential for intestinal homeostasis. We now hypothesize that the normal lymphocyte balance within the lamina propria of the intestine can be achieved via administration of ATRA which restores mucosal integrity by preventing the loss of ISCs. Using both in vivo and in vitro strategies, we now demonstrate that Th17 recruitment and Treg depletion lead to increased apoptosis within ISC niches, significantly impairing proliferative capacity and mucosal healing. ATRA exerted its protective effects by preventing T cell imbalance, ultimately leading to the protection of the ISC pool preventing the development of NEC in mice. These findings raise the exciting possibility that dietary manipulations could prevent and treat NEC by modulating lymphocyte balance and the ISC pool within the newborn small intestine.

The Intricate Link among Gut "Immunological Niche," Microbiota, and Xenobiotics in Intestinal Pathology

Inflammatory bowel diseases (IBDs) are diseases characterized by various degrees of inflammation involving the gastrointestinal tract. Ulcerative colitis and Crohn's disease are characterized by a dysregulated immune response leading to structural gut alterations in genetically predisposed individuals. Diverticular disease is characterized by abnormal immune response to normal gut microbiota. IBDs are linked to a lack of physiological tolerance of the mucosal immune system to resident gut microbiota and pathogens. The disruption of immune tolerance involves inflammatory pathways characterized by an unbalance between the anti-inflammatory regulatory T cells and the proinflammatory Th1/Th17 cells. The interaction among T cell subpopulations and their related cytokines, mediators of inflammation, gut microbiota, and the intestinal mucosa constitute the gut “immunological niche.” Several evidences have shown that xenobiotics, such as rifaximin, can positively modulate the inflammatory pathways at the site of gut immunological niche, acting as anti-inflammatory agents. Xenobiotics may interfere with components of the immunological niche, leading to activation of anti-inflammatory pathways and inhibition of several mediators of inflammation. In summary, xenobiotics may reduce disease-related gut mucosal alterations and clinical symptoms. Studying the complex interplay between gut immunological niche and xenobiotics will certainly open new horizons in the knowledge and therapy of intestinal pathologies.

Analysis of murine and human Treg subsets in inflammatory bowel disease

Previous studies have indicated that regulatory T cells serve essential roles in maintaining intestinal homeostasis, however, the role of different Treg subsets in modulating inflammatory bowel disease has still not been addressed clearly. In the present study, the authors measured the percentage of Foxp3+ IL‑10+ TGF‑β+ natural Tregs, Foxp3‑ IL‑10+ TGF‑β‑ induced Tregs, CD127‑ induced Tregs and CD8+ Tregs at different time points in DSS‑induced experimental colitis model in murine lamina propria lymphocytes, mesenteric lymph node and peripheral blood. In addition, the authors compared the frequency of four Treg subsets in patients diagnosed of ulcerative colitis at different stages with enrolled healthy controls. The percentage of Foxp3+ IL‑10+ TGF‑β+ natural Tregs decreased in acute stage of both human and mice was observed, but proliferated significantly during remittent stage. Foxp3‑ IL‑10+ TGF‑β‑ inducible (i) Treg and CD127‑ iTreg was observed as being significantly decreased percentage in LPL at 4 and 7 days, the frequency of Foxp3‑ IL‑10+ TGF‑β‑ iTreg cells became decreased and CD127‑ iTreg only slightly increased at the chronic stage following DSS induction. However, the proportion of both Foxp3‑ IL‑10+ TGF‑β‑ iTreg and CD127‑ iTreg was nearly unchanged in human IBD. Although intestinal inflammation decreased the percentage of CD8+ Tregs, it remained lower in the remittent stage of human IBD. Only enhanced proliferation of lamina propria lymphocytes‑derived CD8+ Treg was reported at 7 days in dextran sodium sulfate‑induced murine colitis. The results demonstrated that Foxp3+ IL‑10+ TGF‑β+ natural Tregs may serve an essential role in exhibiting suppressive and protecting from immune‑related mucosal injury during chronic stage in inflammatory bowel disease.

Transforming growth factor β: a master regulator of the gut microbiota and immune cell interactions

The relationship between host organisms and their microbiota has co-evolved towards an inter-dependent network of mutualistic interactions. This interplay is particularly well studied in the gastrointestinal tract, where microbiota and host immune cells can modulate each other directly, as well as indirectly, through the production and release of chemical molecules and signals. In this review, we define the functional impact of transforming growth factor-beta (TGF-β) on this complex interplay, especially through its modulation of the activity of local regulatory T cells (Tregs), type 17 helper (Th17) cells, innate lymphoid cells (ILCs) and B cells.

Inflammasome Activation by ATP Enhances Citrobacter rodentium Clearance through ROS Generation

BACKGROUND

Nod-like receptor family, pyrin domain containing 3 (NLRP3) is an important cytosolic sensor of cellular stress and infection. Once activated, NLRP3 forms a multiprotein complex (inflammasome) that triggers the maturation and secretion of interleukin (IL)-1β and IL-18. We aimed to define the consequences of NLRP3 induction, utilizing exogenous adenosine triphosphate (ATP) as an inflammasome activator, to determine if inflammasome activation increases macrophage killing of Citrobacter rodentium and define mechanisms.

METHODS

Bacterial survival was measured using a gentamicin protection assay. Inflammasome activation or inhibition in mouse J774A.1 macrophages were assessed by measuring IL-1β; cytokines and reactive oxygen species (ROS) were measured by ELISA and DCFDA, respectively.

RESULTS

Activation of the inflammasome increased bacterial killing by macrophages and its inhibition attenuated this effect with no impact on phagocytosis or cell death. Furthermore, inflammasome activation suppressed pro-inflammatory cytokines during infection, possibly due to more effective bacterial killing. While the infection increased ROS production, this effect was reduced by inflammasome inhibitors, indicating that ROS is inflammasome-dependent. ROS inhibitors increased bacterial survival in the presence of ATP, suggesting that inflammasome-induced bacterial killing is mediated, at least in part, by ROS activity.

CONCLUSION

Improving inflammasome activity during infection may increase bacterial clearance by macrophages and reduce subsequent microbe-induced inflammation.

Toll-like receptor 4-mediated lymphocyte influx induces neonatal necrotizing enterocolitis

The nature and role of the intestinal leukocytes in necrotizing enterocolitis (NEC), a severe disease affecting premature infants, remain unknown. We now show that the intestine in mouse and human NEC is rich in lymphocytes that are required for NEC development, as recombination activating gene 1–deficient (Rag1–/–) mice were protected from NEC and transfer of intestinal lymphocytes from NEC mice into naive mice induced intestinal inflammation. The intestinal expression of the lipopolysaccharide receptor TLR4, which is higher in the premature compared with full-term human and mouse intestine, is required for lymphocyte influx through TLR4-mediated upregulation of CCR9/CCL25 signaling. TLR4 also mediates a STAT3-dependent polarization toward increased proinflammatory CD3+CD4+IL-17+ and reduced tolerogenic Foxp3+ Treg lymphocytes (Tregs). Th17 lymphocytes were required for NEC development, as inhibition of STAT3 or IL-17 receptor signaling attenuated NEC in mice, while IL-17 release impaired enterocyte tight junctions, increased enterocyte apoptosis, and reduced enterocyte proliferation, leading to NEC. Importantly, TLR4-dependent Th17 polarization could be reversed by the enteral administration of retinoic acid, which induced Tregs and decreased NEC severity. These findings identify an important role for proinflammatory lymphocytes in NEC development via intestinal epithelial TLR4 that could be reversed through dietary modification.

The Effects of IL-22 on the Inflammatory Mediator Production, Proliferation, and Barrier Function of HUVECs

The aim of this study was to investigate the effects of interleukin (IL)-22 on proliferation function and inflammatory mediator production and barrier function of human umbilical vein endothelial cells (HUVECs). The expression of mRNA was detected by RT-PCR. The proliferation ability of cells was evaluated using a cell counting kit assay. Real-time quantitative PCR and Western blot were used to detect the expression of inflammatory mediators. The endothelial barrier permeability was assessed by measuring permeability to FITC-labeled dextran. The distribution of occludin was detected by immunofluorescence. IL-22R1 mRNA expression was noted in HUVECs. IL-22 could enhance the proliferation ability of HUVECs and suppress lipopolysaccharide (LPS)-induced proliferation inhibition in these cells. IL-22 also enhanced the production of CCL2 and CCL20 by HUVECs. Besides, IL-22 could improve barrier function and decrease LPS-induced increased cellular permeability and inhibit the LPS-induced destruction of occludin in HUVECs. IL-22 may play a protective role in the development of vasculitis.

Comorbidity between depression and inflammatory bowel disease explained by immune-inflammatory, oxidative, and nitrosative stress; tryptophan catabolite; and gut-brain pathways

The nature of depression has recently been reconceptualized, being conceived as the clinical expression of activated immune-inflammatory, oxidative, and nitrosative stress (IO&NS) pathways, including tryptophan catabolite (TRYCAT), autoimmune, and gut-brain pathways. IO&NS pathways are similarly integral to the pathogenesis of inflammatory bowel disease (IBD). The increased depression prevalence in IBD associates with a lower quality of life and increased morbidity in IBD, highlighting the role of depression in modulating the pathophysiology of IBD.This review covers data within such a wider conceptualization that better explains the heightened co-occurrence of IBD and depression. Common IO&NS underpinning between both disorders is evidenced by increased pro-inflammatory cytokine levels, eg, interleukin-1 (IL-1) and tumor necrosis factor-α, IL-6 trans-signalling; Th-1- and Th-17-like responses; neopterin and soluble IL-2 receptor levels; positive acute phase reactants (haptoglobin and C-reactive protein); lowered levels of negative acute phase reactants (albumin, transferrin, zinc) and anti-inflammatory cytokines (IL-10 and transforming growth factor-β); increased O&NS with damage to lipids, proteinsm and DNA; increased production of nitric oxide (NO) and inducible NO synthase; lowered plasma tryptophan but increased TRYCAT levels; autoimmune responses; and increased bacterial translocation. As such, heightened IO&NS processes in depression overlap with the biological underpinnings of IBD, potentially explaining their increased co-occurrence. This supports the perspective that there is a spectrum of IO&NS disorders that includes depression, both as an emergent comorbidity and as a contributor to IO&NS processes. Such a frame of reference has treatment implications for IBD when "comorbid" with depression.

Vaginal Mucosal Homeostatic Response May Determine Pregnancy Outcome in Women With Bacterial Vaginosis: A Pilot Study

Bacterial vaginosis (BV) is considered as a trigger for an inflammatory response that could promote adverse pregnancy outcome (APO). We hypothesized that BV-related inflammation could be counterbalanced by anti-inflammatory and mucosal homeostatic responses that could participate in pregnancy outcomes.A total of 402 vaginal self-samples from pregnant women in their first trimester were screened by Nugent score. In this population, we enrolled 23 pregnant women with BV but without APO, 5 pregnant women with BV and developing APO, 21 pregnant women with intermediate flora, and 28 random control samples from pregnant women without BV or APO.BV without APO in pregnant women was associated with 28-fold interleukin-8, 5-fold interleukin-10, and 40-fold interleukin-22 increases in expression compared to controls. BV associated with APO in pregnant women shared 4-fold increase in tumor necrosis factor, 100-fold decrease in interleukin-10, and no variation in interleukin-22 expressions compared to controls. Next-generation sequencing of vaginal microbiota revealed a shift from obligate anaerobic bacteria dominance in BV without APO pregnant women to Lactobacillus dominance microbiota in BV with APO.Our results show that the anti-inflammatory and mucosal homeostatic responses to BV may determine outcome of pregnancy in the setting of BV possibly through effects on the vaginal microbiota.

Berberine ameliorates TNBS induced colitis by inhibiting inflammatory responses and Th1/Th17 differentiation

Th1 and Th17 cells, and their associated cytokines, have been associated with the pathogenesis of Crohn's disease. Berberine (BBR), a compound long used in traditional Chinese medicines, has been reported to have therapeutic effects in treating experimental colitis. In this study, we show that BBR had a protective effect on mice with TNBS-induced colitis. BBR inhibited levels of IFN-γ, IL-17, IL-6, IL-1β and TNF-α both in the local colon and sera, and transiently increased levels of IL-22. BBR also markedly increased sIgA expression in the colon. BBR had pronounced effects on macrophage populations. Treatment with BBR adjusted the M2/M1 ratio. In addition, BBR exerted effects on adaptive immunity by suppressing numbers of Th1 and Th17 cells, as well as expression levels of their associated cytokines and transcriptional factors. BBR downregulated STAT3 and STAT1 phosphorylation, and inhibited phosphorylation of NF-kB. In vitro experiments showed that BBR inhibited the differentiation of Th17 and, to a lesser degree, Th1 cells, without affecting regulatory T cells. Therefore, we conclude that BBR plays a regulatory role in modulating the balance of immune responses in TNBS-induced colitis. Our study will help us understand the regulatory mechanisms exerted by BBR in the treatment of IBD.

Expression of T helper type 17 (Th17)-associated cytokines and toll-like receptor 4 and their correlation with Foxp3 positive cells in rectal biopsies of horses with clinical signs of inflammatory bowel disease

Inflammatory bowel disease (IBD) in horses is an idiopathic disorder, encompassing different types of chronic intestinal inflammation. The pathogenesis of the disease remains to be established, but it has been suggested that an imbalance between regulatory T cells (Tregs) and T helper 17 (Th17)-associated cytokines and altered toll-like receptor 4 (TLR4) expression is associated with intestinal inflammation in other species. The aim of the present study was to quantify Tregs in rectal biopsies from horses affected with IBD by immunohistochemistry and to evaluate expression of genes encoding interleukin (IL)-12p40, IL-17A, IL-23p19 and TLR4 by real-time quantitative PCR. Rectal biopsies from 11 healthy horses and 11 horses with clinical signs of IBD, showing inflammation classified as chronic simple proctitis (CSP) or chronic active simple proctitis (CASP), were evaluated. Expression of IL-17A mRNA was greater in horses affected with CASP compared with horses with CSP or healthy horses. In contrast, expression of IL-12p40 was lower in horses with CSP compared with horses with CASP or healthy horses. TLR4 expression was greater in horses with CASP compared with healthy horses. A positive correlation was seen between the numbers of Tregs and expression of IL-17A and IL-23p19. An association was demonstrated between the histopathological pattern of inflammation, cytokine profile and number of infiltrating Tregs. The research findings suggest that Th17 cells are involved in active IBD, possibly through recruitment of neutrophils via IL-17A, in combination with inadequate suppression of the inflammatory response by Tregs.

Fibrosis Related Inflammatory Mediators: Role of the IL-10 Cytokine Family

Importance of chronic fibroproliferative diseases (FDs) including pulmonary fibrosis, chronic kidney diseases, inflammatory bowel disease, and cardiovascular or liver fibrosis is rapidly increasing and they have become a major public health problem. According to some estimates about 45% of all deaths are attributed to FDs in the developed world. Independently of their etiology the common hallmark of FDs is chronic inflammation. Infiltrating immune cells, endothelial, epithelial, and other resident cells of the injured organ release an orchestra of inflammatory mediators, which stimulate the proliferation and excessive extracellular matrix (ECM) production of myofibroblasts, the effector cells of organ fibrosis. Abnormal amount of ECM disturbs the original organ architecture leading to the decline of function. Although our knowledge is rapidly expanding, we still have neither a diagnostic tool to detect nor a drug to specifically target fibrosis. Therefore, there is an urgent need for the more comprehensive understanding of the pathomechanism of fibrosis and development of novel diagnostic and therapeutic strategies. In the present review we provide an overview of the common key mediators of organ fibrosis highlighting the role of interleukin-10 (IL-10) cytokine family members (IL-10, IL-19, IL-20, IL-22, IL-24, and IL-26), which recently came into focus as tissue remodeling-related inflammatory cytokines.

1,25-dihydroxyvitamin D3 regulates the development of chronic colitis by modulating both T helper (Th)1 and Th17 activation

T helper (Th)1 and Th17 cells play a critical role in inflammatory bowel disease (IBD). 1,25-dihydroxyvitamin D3 (1,25(OH)2 D3 ) has emerged as a direct regulator of immune system function. Mice were grouped as follows: Control group (received PBS, n = 10), DSS group (received 2% DSS and PBS, n = 10), and DSS+VD group (received 2% DSS and 1,25(OH)2 D3 , n = 10). The disease activity index (DAI), colon length, and damage store of the mice were observed; the spleen length, weight, spleen index, and mononuclear cells of spleen were measured; mononuclear cells from mesenteric lymph nodes (MLN) were measured, and the levels of Th 1 and Th17 cytokines in the colon mucosa and spleen were measured. Mice in the DSS group developed severe diarrhea, rectal bleeding, and marked BW loss. Histological examination revealed extensive ulceration and inflammatory cell infiltration in the colon, and the structure of the spleen was disordered, infiltrated with inflammatory cytokines in red pulp. In the DSS group, mononuclear cell numbers from MLN and spleen were increased, and enhanced proteins and mRNA levels of Th 1 and Th17 cytokines were detected. In the DSS+VD group, 1,25(OH)2 D3 ameliorated the inflammation of the colon and spleen. In addition, 1,25(OH)2 D3 down-regulated the levels of Th 1 and Th17 cytokines. 1,25(OH)2 D3 represents a novel therapeutic drug for UC, which may correlate to inhibit the activation of Th1 and Th17 cells.

Lactobacillus acidophilus suppresses colitis-associated activation of the IL-23/Th17 axis

The aim of this paper is to determine the modulatory effects of Lactobacillus acidophilus on the IL-23/Th17 immune axis in experimental colitis. DSS-induced mouse models of UC were to be saline, hormones, and different concentrations of Lactobacillus acidophilus intervention. The expression of interleukin- (IL-) 17, tumor necrosis factor α (TNFα), IL-23, transforming growth factor β1 (TGFβ1), signal transducer and activator of transcription 3 (STAT3), and phosphorylated (p)-STAT3 was examined by RT-PCR, Western blotting, and immunohistochemical analysis. And the results showed that administration of L. acidophilus suppressed Th17 cell-mediated secretion of proinflammatory cytokine IL-17 through downregulation of IL-23 and TGFβ1 expression and downstream phosphorylation of p-STAT3.

MicroRNAs: new players in IBD

MicroRNAs (miRNAs) are small non-coding RNAs, 18-23 nucleotides long, which act as post-transcriptional regulators of gene expression. miRNAs are strongly implicated in the pathogenesis of many common diseases, including IBDs. This review aims to outline the history, biogenesis and regulation of miRNAs. The role of miRNAs in the development and regulation of the innate and adaptive immune system is discussed, with a particular focus on mechanisms pertinent to IBD and the potential translational applications.

Th17 cells in autoimmune diseases

Th17 cells are a new subset of CD4(+) T cells involved in the clearance of extracellular pathogens and fungi. Accumulating evidence suggests that Th17 cells and their signature cytokines have a pivotal role in the pathogenesis of multiple autoimmune-mediated inflammatory diseases. Here, we summarize recent research progress on Th17 function in the development and pathogenesis of autoimmune diseases. We also propose to identify new small molecule compounds to manipulate Th17 function for potential therapeutic application to treat human autoimmune diseases, including rheumatoid arthritis, systemic lupus erythematosus, Sjögren's syndrome, inflammatory bowel disease, and multiple sclerosis.