Chong He

miR-10a inhibits dendritic cell activation and Th1/Th17 cell immune responses in IBD

Objective Although both innate and adaptive responses to microbiota have been implicated in the pathogenesis of IBD, it is still largely unknown how they are regulated during intestinal inflammation. In this report, we investigated the role of microRNA (miR)-10a, a small, non-coding RNA, in the regulation of innate and adaptive responses to microbiota in IBD. Methods miR-10a expression was analysed in the inflamed mucosa of IBD patients treated with or without antitumour necrosis factor (anti-TNF) monoclonal antibodies (mAb) (infliximab) by qRT-PCR. Human monocyte-derived dendritic cells (DC) and IBD CD4+ T cells were transfected with miR-10a precursor to define their effect on the function of DC and CD4+ T cells. Results The expression of miR-10a was markedly decreased, while NOD2 and interleukin (IL)-12/IL-23p40 were significantly increased, in the inflamed mucosa of IBD patients compared with those in healthy controls. Commensal bacteria, TNF and interferon-γ inhibited human DC miR-10a expression in vitro. Anti-TNF mAb treatment significantly promoted miR-10a expression, whereas it markedly inhibited NOD2 and IL-12/IL-23p40 in the inflamed mucosa. We further identified NOD2, in addition to IL-12/IL-23p40, as a target of miR-10a. The ectopic expression of the miR-10a precursor inhibited IL-12/IL-23p40 and NOD2 in DC. Moreover, miR-10a was found to markedly suppress IBD T helper (Th)1 and Th17 cell responses. Conclusions Our data indicate that miR-10a is decreased in the inflamed mucosa of IBD and downregulates mucosal inflammatory response through inhibition of IL-12/IL-23p40 and NOD2 expression, and blockade of Th1/Th17 cell immune responses. Thus, miR-10a could play a role in the pathogenesis and progression of IBD.

miR-301a promotes intestinal mucosal inflammation through induction of IL-17A and TNF-α in IBD

Objective MicroRNA (miR)-301a is known to be involved in the tumourigenesis and pathogenesis of several autoimmune diseases, but it remains unclear whether miR-301a is associated with the pathogenesis of IBD. Methods miR-301a expression was assessed in peripheral blood mononuclear cells (PBMC) and inflamed mucosa of patients with IBD by quantitative real-time-PCR. Peripheral blood CD4+ T cells were transduced with lentivirus-encoding pre-miR-301a (LV-miR-301a) or a reverse complementary sequence of miR-301a (LV-anti-miR-301a), and their differentiation and activation were investigated in vitro. Antisense miR-301a was administered into mice during trinitrobenzene sulphonic acid (TNBS)-induced colitis to determine its role in colitis. Results miR-301a expression was significantly upregulated in PBMC and inflamed mucosa of patients with IBD compared with healthy controls. Stimulation with tumour necrosis factor-α (TNF-α) significantly enhanced miR-301a expression in IBD CD4+ T cells, which was markedly reversed by anti-TNF-α mAb (Infliximab) treatment. Transduction of LV-miR-301a into CD4+ T cells from patients with IBD promoted the Th17 cell differentiation and TNF-α production compared with the cells with expression of LV-anti-miR-301a. SNIP1 as a functional target of miR-301a was reduced in miR-301a expression but increased in LV-anti-miR-301a expression. Knockdown of SNIP1 could enhance Th17 cell differentiation. Furthermore, intracolonical administration of antisense miR-301a in TNBS-induced mouse colitis model significantly decreased numbers of interleukin (IL)-17A+ cells and amounts of pro-inflammatory cytokines (eg, IL-17A, TNF-α) in inflamed colon. Conclusions Our data reveal a novel mechanism in which the elevated miR-301a in PBMC and inflamed mucosa of IBD promotes Th17 cell differentiation through downregulation of SNIP1. Blockade of miR-301a in vivo may serve as a novel therapeutic approach in the treatment of IBD.

Serum Levels of Lipopolysaccharide and 1,3-β-D-Glucan Refer to the Severity in Patients with Crohn’s Disease

Objectives. Interactions between the host and gut microbial community contribute to the pathogenesis of Crohns disease (CD). In this study, we aimed to detect lipopolysaccharide (LPS) and 1,3-β-D-glucan (BG) in the sera of CD patients and clarify the potential role in the diagnosis and therapeutic approaches. Materials and Methods. Serum samples were collected from 46 patients with active CD (A-CD), 22 CD patients at remission stage (R-CD), and 20 healthy controls, and the levels of LPS, BG, and TNF in sera were determined by ELISA. Moreover, sixteen patients with A-CD received anti-TNF monoclonal antibody therapy (infliximab, IFX) at a dose of 5 mg/kg body weight at weeks 0, 2, and 6, and the levels of LPS and BG were also tested at week 12 after the first intravenous infusion. Results. Serum levels of LPS and BG were found to be markedly increased in A-CD patients compared with R-CD patients and healthy controls (P < 0.05). They were also observed to be positively correlated with CDAI, ESR, and SES-CD, respectively (P < 0.05). Furthermore, the levels of TNF in sera had a significant correlation with LPS and BG, respectively. The concentrations of LPS and BG were demonstrated to be significantly downregulated in the sera of A-CD patients 12 weeks after IFX treatment (P < 0.05), suggesting that blockade of TNF could inhibit bacterial endotoxin absorption, partially through improving intestinal mucosal barrier. Conclusions. Serum levels of LPS and BG are significantly increased in A-CD patients and positively correlated with the severity of the disease. Blockade of intestinal mucosal inflammation with IFX could reduce the levels of LPS and BG in sera. Therefore, this study has shed some light on measurement of serum LPS and BG in the diagnosis and treatment of CD patients.

Unexpected Regulatory Role of CCR9 in Regulatory T Cell Development.

T cells reactive to microbiota regulate the pathogenesis of inflammatory bowel disease (IBD). As T cell trafficking to intestines is regulated through interactions between highly specific chemokine-chemokine receptors, efforts have been made to develop intestine-specific immunosuppression based on blocking these key processes. CCR9, a gut-trophic chemokine receptor expressed by lymphocytes and dendritic cells, has been implicated in the regulation of IBD through mediating recruitment of T cells to inflamed sites. However, the role of CCR9 in inducing and sustaining inflammation in the context of IBD is poorly understood. In this study, we demonstrate that CCR9 deficiency in effector T cells and Tregs does not affect the development of colitis in a microbiota antigen-specific, T cell-mediated model. However, Treg cells express higher levels of CCR9 compared to those in effector T cells. Interestingly, CCR9 inhibits Treg cell development, in that CCR9-/- mice demonstrate a high level of Foxp3+ Tregs, and ligation of CCR9 by its ligand CCL25 inhibits Treg cell differentiation in vitro. Collectively, our data indicate that in addition to acting as a gut-homing molecule, CCR9 signaling shapes immune responses by inhibiting Treg cell development.

Hypoxia inducible factor-1α-induced interleukin-33 expression in intestinal epithelia contributes to mucosal homeostasis in inflammatory bowel disease

Intestinal epithelial cells (IECs), an important barrier to gut microbiota, are subject to low oxygen tension, particularly during intestinal inflammation. Hypoxia inducible factor‐1α (HIF‐1α) is expressed highly in the inflamed mucosa of inflammatory bowel disease (IBD) and functions as a key regulator in maintenance of intestinal homeostasis. However, how IEC‐derived HIF‐1α regulates intestinal immune responses in IBD is still not understood completely. We report here that the expression of HIF‐1α and IL‐33 was increased significantly in the inflamed mucosa of IBD patients as well as mice with colitis induced by dextran sulphate sodium (DSS). The levels of interleukin (IL)−33 were correlated positively with that of HIF‐1α. A HIF‐1α‐interacting element was identified in the promoter region of IL‐33, indicating that HIF‐1α activity regulates IL‐33 expression. Furthermore, tumour necrosis factor (TNF) facilitated the HIF‐1α‐dependent IL‐33 expression in IEC. Our data thus demonstrate that HIF‐1α‐dependent IL‐33 in IEC functions as a regulatory cytokine in inflamed mucosa of IBD, thereby regulating the intestinal inflammation and maintaining mucosal homeostasis.

Serum bacterial toxins are related to the progression of inflammatory bowel disease

Abstract Objectives. Inflammatory bowel disease (IBD), including Crohn’s disease (CD) and ulcerative colitis (UC), is an autoimmune disease. Disorder of intestinal microbes is thought to play a critical role in the pathogenesis of IBD. Detection of bacterial toxins could become a new approach to judge the situation of this disease. Materials and methods. Serum samples were collected from 142 IBD patients and 40 healthy donors as well as 15 CD patients with anti-tumor necrosis factor (TNF) monoclonal antibody (infliximab [IFX]). Enzyme-linked immunosorbent assay kits for Clostridium difficile, Escherichia coli O157, salmonella, and Staphylococcus aureus were used to analyze these bacterial toxins in sera. Results. The positive rates of bacterial toxins from C. difficile, E. coli O157, salmonella, and S. aureus in the IBD patients were found in low incidences and associated with disease duration, colonic involvement, and treatment with prednisone and immunomodulators. The active CD and UC patients had significant higher positive rates of these bacterial toxins than those in remission or healthy controls. Blockage of TNF with IFX in CD patients resulted in significant decreases of the levels of toxins of C. difficile, E. coli O157, salmonella, and S. aureus in sera. Conclusions. Some bacterial toxins are present in the sera of active IBD patients, and patients with long disease duration, colonic involvement, or treatment with prednisone and immunomodulators are more susceptible to bacterial infection. Inhibition of inflammation with IFX would reduce the bacterial toxins via improvement of intestinal inflammation. Detecting bacteria-derived toxins in sera can be used to predict the progression of IBD.

Hypoxia inducible factor-1α-induced IL-33expression in intestinal epithelia contributes to mucosal homeostasis ininflammatory bowel disease

Intestinal epithelial cells (IECs), an important barrier to gut microbiota, are subject to low oxygen tension, particularly during intestinal inflammation. Hypoxia inducible factor‐1α (HIF‐1α) is expressed highly in the inflamed mucosa of inflammatory bowel disease (IBD) and functions as a key regulator in maintenance of intestinal homeostasis. However, how IEC‐derived HIF‐1α regulates intestinal immune responses in IBD is still not understood completely. We report here that the expression of HIF‐1α and IL‐33 was increased significantly in the inflamed mucosa of IBD patients as well as mice with colitis induced by dextran sulphate sodium (DSS). The levels of interleukin (IL)−33 were correlated positively with that of HIF‐1α. A HIF‐1α‐interacting element was identified in the promoter region of IL‐33, indicating that HIF‐1α activity regulates IL‐33 expression. Furthermore, tumour necrosis factor (TNF) facilitated the HIF‐1α‐dependent IL‐33 expression in IEC. Our data thus demonstrate that HIF‐1α‐dependent IL‐33 in IEC functions as a regulatory cytokine in inflamed mucosa of IBD, thereby regulating the intestinal inflammation and maintaining mucosal homeostasis.

Severe Henoch-Schönlein purpura with infliximab for ulcerative colitis

Infliximab (IFX) is an anti-tumor necrosis factor chimeric antibody that is effective for treatment of autoimmune disorders such as Crohns disease and ulcerative colitis (UC). IFX is well tolerated with a low incidence of adverse effects such as infections, skin reactions, autoimmunity, and malignancy. Dermatological manifestations can appear as infusion reaction, vasculitis, cutaneous infections, psoriasis, eczema, and skin cancer. Here, we present an unusual case of extensive and sporadic subcutaneous ecchymosis in a 69-year-old woman with severe UC, partial colectomy and cecostomy, following her initial dose of IFX. The reaction occurred during infliximab infusion, and withdrawal of IFX led to gradual alleviation of her symptoms. We concluded that Henoch-Schönlein purpura, a kind of leukocytoclastic vasculitis, might have contributed to the development of the bruising. Although the precise mechanisms of the vasculitis are still controversial, such a case highlights the importance of subcutaneous adverse effects in the management of UC with IFX.

Intestinal wall thickness detected by multidetector spiral computed tomography enterography predicts the disease severity of Crohn's disease

Abstract Objective. Multidetector spiral computed tomography enterography (MSCTE) and ileocolonoscopy are used in evaluating inflammatory situation of Crohns disease (CD) patients. The purpose of this study was to determine the disease severity of CD patients by combining the intestinal wall thickness by MSCTE with ileocolonoscopy. Material and methods. This retrospective study included 50 patients with terminal ileal CD. Diagnosis was confirmed based on clinical features, endoscopy, and pathology. Patients underwent both MSCTE and ileocolonoscopy. Ileal wall thickness was measured and the disease severity was evaluated by CD activity index (CDAI). Intestinal mucosal lesions were scored by the simple endoscopic score for CD (SES-CD). Results. Of the 50 patients with active terminal ileal CD, the comparison of scores between SES-CD and CDAI showed significant association with Spearmans rank correlation coefficient (p < 0.01). There were statistically significant correlation between the wall thickness and the SES-CD (p < 0.0001) as well as CDAI (p < 0.001), respectively, but no significant correlation between the wall thickness and the C-reactive protein (CRP) was found (p = 0.43). Moreover, we found that the wall thickness was preferential to predict the disease severity in the terminal ileal CD. Conclusion. MSCTE, in combination with ileocolonoscopy, is reliable to identify disease severity in CD patients and provides more accurate information in the diagnosis and treatment.

Smad nuclear interacting protein 1 (SNIP1) inhibits intestinal inflammation through regulation of epithelial barrier function

Smad nuclear interacting protein 1 (SNIP1) has been implicated in the pathogenesis of inflammatory bowel disease (IBD). However, the mechanisms involved are still largely unknown. Our results demonstrated that SNIP1 was markedly decreased in intestinal epithelial cells (IEC) from IBD patients compared with healthy controls. Impaired expression of SNIP1 caused a significant decrease of transepithelial electrical resistance but an increase of fluorescein isothiocyanate-dextran flux in Caco-2 monolayers, whereas overexpression of SNIP1 reversed such effects. Overexpression of SNIP1 also inhibited the activity of NF-κB p65 and proinflammatory cytokine production (e.g., TNF-α, IL-1β, and IL-8) by IEC. Importantly, supplementation of exogenous SNIP1 significantly ameliorated intestinal mucosal inflammation in experimental colitis, characterized by less-severe intestinal epithelial barrier damage and decreased proinflammatory cytokine production. Our data thus demonstrated a novel mechanism whereby SNIP1 regulates intestinal inflammation through modulating intestinal epithelial barrier function. Targeting SNIP1 may provide a therapeutic approach for the treatment of IBD.