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Background and AimsMany inflammatory bowel disease (IBD) patients do not respond to medical therapy. Tofacitinib is a first-in-class, partially selective inhibitor of Janus kinase, recently approved for treating patients with ulcerative colitis (UC). We describe our experience with the use of tofacitinib for treatment of patients with moderate-to-severe IBD.MethodsThis is a retrospective, observational study of the use of tofacitinib in IBD. Patients with medically resistant IBD were treated orally with 5 mg or 10 mg twice daily. Clinical response and adverse events were assessed at 8, 26, and 52 weeks. Objective response was assessed endoscopically, radiologically, and biochemically.Results58 patients (53 UC, 4 Crohn’s, 1 pouchitis) completed at least 8 weeks of treatment with tofacitinib. 93% of the patients previously failed treatment with anti-TNF. At 8 weeks of treatment, 21 patients (36%) achieved a clinical response, and 19 (33%) achieved clinical remission. Steroid-free remission at 8 weeks was achieved in 15 patients (26%). Of the 48 patients followed for 26 weeks, 21% had clinical, steroid-free remission. Of the 26 patients followed for 12 months, 27% were in clinical, steroid-free remission. Twelve episodes of systemic infections were noted, mostly while on concomitant steroids. One episode of herpes zoster infection was noted during follow-up.ConclusionsIn this cohort of patients with moderate-to-severe, anti-TNF resistant IBD, tofacitinib induced clinical response in 69% of the patients. 27% were in clinical, steroid-free remission by 1 year of treatment. Tofacitinib is an effective therapeutic option for this challenging patient population.

Inflammatory bowel disease (IBD) is an important etiologic factor in the development of colorectal cancer. However, the mechanism underlying carcinogenesis through chronic inflammation is still unknown. Activation-induced cytidine deaminase (AID) is induced by the inflammation and involved in various human carcinogenesis via its mutagenic activity. In the current study, we investigated whether the inflammation/AID axis plays an integral role in the development of colitis-associated cancers. Inflammation in the cecum was more severe than that in other colonic regions, and endogenous AID expression was enhanced most prominently in the inflamed cecal mucosa of interleukin (IL)-10 −/− mice. Blockade of tumor necrosis factor (TNF)-α and IL-12 significantly suppressed AID expression. Although proinflammatory cytokine expression was comparable between IL-10 −/− AID +/+ and IL-10 −/− AID −/− mice, sequencing analyses revealed a significantly lower incidence of somatic mutations in Trp53 gene in the colonic mucosa of IL-10 −/− AID −/− than IL-10 −/− AID +/+ mice. Colon cancers spontaneously developed in the cecum in 6 of 22 (27.2%) IL-10 −/− AID +/+ mice. In contrast, none of the IL-10 −/− AID −/− mice developed cancers except only one case of neoplasia in the distal colon. These findings suggest that the proinflammatory cytokine-induced aberrant production of AID links colonic inflammation to an enhanced genetic susceptibility to oncogenic mutagenesis. Targeting AID could be a novel strategy to prevent colitis-associated colon carcinogenesis irrespective of ongoing colonic inflammation.

Matrix metalloproteinases play an important role in extracellular matrix remodelling. It has been proposed that matrix metalloproteinase-9 (MMP-9) is involved in epithelial damage in ulcerative colitis (UC). However, to our knowledge, no data are available in terms of MMP-9 expression in microscopic colitis. Determination of mucosal protein expression levels of MMP-9 in lymphocytic colitis (LC), collagenous colitis (CC) and UC. MMP-9 immunohistochemical expressions were analyzed in paraffin-embedded tissue samples by immunohistochemistry including patients with LC, CC, UC, active diverticulitis, inactive diverticular disease and healthy control subjects. UC was also subgrouped according to the severity of inflammation. Immunostaining was determined semiquantitatively. Independent colonic biopsies from healthy and severe UC cases were used for gene expression analyses. For further comparison MMP-9 serum antigen levels were also determined in patients with UC and control patients without macroscopic or microscopic changes during colonoscopy. MMP-9 mucosal expression was significantly higher in UC (26.7 ± 19.5%) compared to LC (6.6 ± 9.3%), CC (6.4 ± 7.6%), active diverticulitis (5.33 ± 2.4%), inactive diverticular disease (5.0 ± 2.2%) and controls (6.3 ± 2.6%) ( P  < 0.001). The immunohistochemical expression of MMP-9 in LC and CC was similar as compared to controls. MMP-9 expression was significantly higher in each inflammatory group of UC compared to controls (mild: 11.0 ± 2.8%, moderate: 23.9 ± 3.7%, severe UC: 52.6 ± 3.9% and 6.3 ± 2.6%, respectively, P  < 0.005). The gene expression microarray data and RT-PCR results demonstrated a significantly higher expression of MMP-9 in severely active UC compared to healthy controls ( P  < 0.001). Significantly higher MMP-9 serum antigen concentrations were observed in UC patients compared with the control group ( P  < 0.05). MMP-9 seems to play no role in the inflammatory process of LC and CC. In contrast, the mucosal up-regulation of MMP-9 correlated with the severity of inflammation in UC. The increased MMP-9 expression could contribute to the severity of mucosal damage in active UC.

Abstract Background Phosphatase and tensin homolog (Pten) is capable of mediating microbe-induced immune responses in the gut. Thus, Pten deficiency in the intestine accelerates colitis development in Il10-/- mice. As some ambient pollutants inhibit Pten function and exposure to ambient pollutants may increase inflammatory bowel disease (IBD) incidence, it is of interest to examine how Pten inhibition could affect colitis development in genetically susceptible hosts. Methods With human colonic mucosa biopsies from pediatric ulcerative colitis and non-IBD control subjects, we assessed the mRNA levels of the PTEN gene and the gene involved in IL10 responses. The data from the human tissues were corroborated by treating Il10-/-, Il10rb-/-, and wild-type C57BL/6 mice with Pten-specific inhibitor VO-OHpic. We evaluated the severity of mouse colitis by investigating the tissue histology and cytokine production. The gut microbiome was investigated by analyzing the 16S ribosomal RNA gene sequence with mouse fecal samples. Results PTEN and IL10RB mRNA levels were reduced in the human colonic mucosa of pediatric ulcerative colitis compared with non-IBD subjects. Intracolonic treatment of the Pten inhibitor induced colitis in Il10-/- mice, characterized by reduced body weight, marked colonic damage, and increased production of inflammatory cytokines, whereas Il10rb-/- and wild-type C57BL/6 mice treated with the inhibitor did not develop colitis. Pten inhibitor treatment changed the fecal microbiome, with increased abundance of colitogenic bacteria Bacteroides and Akkermansia in Il10-/- mice. Conclusions Loss of Pten function increases the levels of colitogenic bacteria in the gut, thereby inducing deleterious colitis in an Il10-deficient condition.

Background/Aim: In previous studies, we described the beneficial effects of bifidobacteria-fermented milk in patients with ulcerative colitis (UC). Here, we examined the effects of a live Bifidobacterium breve strain Yakult, a probiotic contained in bifidobacteria-fermented milk, and galacto-oligosaccharide (GOS) as synbiotics in UC patients. Methods: Forty-one patients with mild to moderate UC were assigned to two groups; one group was treated with the synbiotics and the other was not (control). The treatment group ingested 1 g of the probiotic powder (10 9 CFU/g) three times a day, and 5.5 g of GOS once a day for one year. At the start and the end of this study, colonoscopic index and the amount of myeloperoxidase in a lavage solution were used as disease activity indices. Bacterial counts in the feces at the start and the end of this study were also examined. Results: After a one-year treatment with the synbiotics, the clinical status of the UC patients as assessed by colonoscopy, significantly improved. Furthermore, the amount of myeloperoxidase in the lavage also decreased in these patients after the synbiotic treatment. The synbiotics significantly reduced the fecal counts of Bacteroidaceae and fecal pH. Conclusion: Administration of live B. breve strain Yakult and GOS can improve the clinical condition of patients with UC. These results encouraged us to perform a large-scale randomized, placebo-controlled trial.

Emerging research supports that triclosan (TCS), an antimicrobial agent found in thousands of consumer products, exacerbates colitis and colitis-associated colorectal tumorigenesis in animal models. While the intestinal toxicities of TCS require the presence of gut microbiota, the molecular mechanisms involved have not been defined. Here we show that intestinal commensal microbes mediate metabolic activation of TCS in the colon and drive its gut toxicology. Using a range of in vitro, ex vivo, and in vivo approaches, we identify specific microbial β-glucuronidase (GUS) enzymes involved and pinpoint molecular motifs required to metabolically activate TCS in the gut. Finally, we show that targeted inhibition of bacterial GUS enzymes abolishes the colitis-promoting effects of TCS, supporting an essential role of specific microbial proteins in TCS toxicity. Together, our results define a mechanism by which intestinal microbes contribute to the metabolic activation and gut toxicity of TCS, and highlight the importance of considering the contributions of the gut microbiota in evaluating the toxic potential of environmental chemicals. Triclosan (TCS), an antimicrobial agent commonly found in consumer products, has been reported to exacerbates colitis in animal models. Here, using in vitro and in vivo approaches, the authors show that gut bacterial enzymes can drive the metabolic activation and gut toxicity of TCS, highlighting an important role of intestinal microbial factors in the complex etiology of colitis.

Heparanase is an endo-β-D-glucuronidase capable of cleaving heparan sulfate (HS) side chains at a limited number of sites, yielding HS fragments of still appreciable size (∼5–7 kDa). Heparanase activity has long been detected in a number of cell types and tissues. Importantly, heparanase activity correlated with the metastatic potential of tumor-derived cells, attributed to enhanced cell dissemination as a consequence of HS cleavage and remodeling of the extracellular matrix barrier. Similarly, heparanase activity was implicated in neovascularization, inflammation and autoimmunity, involving migration of vascular endothelial cells and activated cells of the immune system. The involvement of heparanase in inflammatory processes of the gastrointestinal tract has not been examined. Here, we utilized immunohistochemical analysis to investigate heparanase expression in acute and chronic inflammatory conditions. Heparanase expression was not detected in specimens derived from normal colon tissue. In contrast, strong heparanase staining was observed in Crohn’s disease and ulcerative colitis, but not in infectious colitis. Interestingly, heparanase staining was primarily observed in epithelial rather than immune cells. Importantly, un-fractionated as well as low molecular weight heparin (enoxaparin), which exhibit a strong inhibitory activity towards heparanase, have proven efficacious in ulcerative colitis and Crohn’s disease patients, suggesting that heparanase is actively involved in these pathologies and thus may be considered as a target for the development of anti-inflammatory therapies.

The Tet2 enzyme, which catalyses de novo hydroxymethylation of DNA, is shown here to act as a transcriptional repressor by recruiting the histone deacetylase Hdac2 to the Il6 promoter in the course of resolution of the LPS-induced inflammatory response. Anti-inflammatory action of Tet2 The regulation of immunity and inflammation by Tet proteins independent of their epigenetic role in modulating DNA methylation remains largely unknown. The Tet2 enzyme, which is known to catalyse de novo hydroxymethylation of DNA, is shown here to have a novel role in regulating inflammation. Specifically Tet2 acts as a transcriptional repressor by recruiting the histone deacetylase inhibitor Hdac2 to the interleukin-6 promoter in the course of resolution of the lipopolysaccharide (LPS)-induced inflammatory response. Epigenetic modifiers have fundamental roles in defining unique cellular identity through the establishment and maintenance of lineage-specific chromatin and methylation status 1 . Several DNA modifications such as 5-hydroxymethylcytosine (5hmC) are catalysed by the ten eleven translocation (Tet) methylcytosine dioxygenase family members 2 , and the roles of Tet proteins in regulating chromatin architecture and gene transcription independently of DNA methylation have been gradually uncovered 3 . However, the regulation of immunity and inflammation by Tet proteins independent of their role in modulating DNA methylation remains largely unknown. Here we show that Tet2 selectively mediates active repression of interleukin-6 (IL-6) transcription during inflammation resolution in innate myeloid cells, including dendritic cells and macrophages. Loss of Tet2 resulted in the upregulation of several inflammatory mediators, including IL-6, at late phase during the response to lipopolysaccharide challenge. Tet2-deficient mice were more susceptible to endotoxin shock and dextran-sulfate-sodium-induced colitis, displaying a more severe inflammatory phenotype and increased IL-6 production compared to wild-type mice. IκBζ, an IL-6-specific transcription factor, mediated specific targeting of Tet2 to the Il6 promoter, further indicating opposite regulatory roles of IκBζ at initial and resolution phases of inflammation. For the repression mechanism, independent of DNA methylation and hydroxymethylation, Tet2 recruited Hdac2 and repressed transcription of Il6 via histone deacetylation. We provide mechanistic evidence for the gene-specific transcription repression activity of Tet2 via histone deacetylation and for the prevention of constant transcription activation at the chromatin level for resolving inflammation.

Epithelial cell death in intestinal inflammatory disease Two groups identify the regulation of death-receptor-induced necroptosis as an epithelial intrinsic mechanism that is important for the maintenance of immune homeostasis and the prevention of intestinal inflammation in mice. Welz et al . describe an unexpected physiological function for FADD (Fas-associated protein with death domain), an adaptor protein required for death-receptor-induced apoptosis. Mice with intestinal epithelial specific knockout of FADD develop severe colon inflammation due to increased death of FADD-deficient colonic epithelial cells. Günther et al . report a novel and unexpected function of caspase-8 in maintaining immune homeostasis in the gut. Caspase-8 expression by gut epithelial cells is shown to protect mice from TNF-mediated Paneth cell death and intestinal inflammation. Increased expression of the protein RIP3 was associated with the TNF-induced pathology, and elevated RIP3 expression was also found in intestinal Paneth cells of patients with Crohn's disease. Dysfunction of the intestinal epithelium is believed to result in the excessive translocation of commensal bacteria into the bowel wall that drives chronic mucosal inflammation in Crohn’s disease, an incurable inflammatory bowel disease in humans characterized by inflammation of the terminal ileum 1 . In healthy individuals, the intestinal epithelium maintains a physical barrier, established by the tight contact of cells. Moreover, specialized epithelial cells such as Paneth cells and goblet cells provide innate immune defence functions by secreting mucus and antimicrobial peptides, which hamper access and survival of bacteria adjacent to the epithelium 2 . Epithelial cell death is a hallmark of intestinal inflammation and has been discussed as a possible pathogenic mechanism driving Crohn’s disease in humans 3 . However, the regulation of epithelial cell death and its role in intestinal homeostasis remain poorly understood. Here we demonstrate a critical role for caspase-8 in regulating necroptosis of intestinal epithelial cells (IECs) and terminal ileitis. Mice with a conditional deletion of caspase-8 in the intestinal epithelium ( Casp8 ΔIEC ) spontaneously developed inflammatory lesions in the terminal ileum and were highly susceptible to colitis. Casp8 ΔIEC mice lacked Paneth cells and showed reduced numbers of goblet cells, indicating dysregulated antimicrobial immune cell functions of the intestinal epithelium. Casp8 ΔIEC mice showed increased cell death in the Paneth cell area of small intestinal crypts. Epithelial cell death was induced by tumour necrosis factor (TNF)-α, was associated with increased expression of receptor-interacting protein 3 ( Rip3 ; also known as Ripk3 ) and could be inhibited on blockade of necroptosis. Lastly, we identified high levels of RIP3 in human Paneth cells and increased necroptosis in the terminal ileum of patients with Crohn’s disease, suggesting a potential role of necroptosis in the pathogenesis of this disease. Together, our data demonstrate a critical function of caspase-8 in regulating intestinal homeostasis and in protecting IECs from TNF-α-induced necroptotic cell death.

Several enteric pathogens can gain specific metabolic advantages over other members of the microbiota by inducing host pathology and inflammation. The pathogen Clostridium difficile is responsible for a toxin-mediated colitis that causes 450,000 infections and 15,000 deaths in the United States each year 1 ; however, the molecular mechanisms by which C. difficile benefits from this pathology remain unclear. To understand how the metabolism of C. difficile adapts to the inflammatory conditions that its toxins induce, here we use RNA sequencing to define, in a mouse model, the metabolic states of wild-type C. difficile and of an isogenic mutant that lacks toxins. By combining bacterial and mouse genetics, we demonstrate that C. difficile uses sorbitol derived from both diet and host. Host-derived sorbitol is produced by the enzyme aldose reductase, which is expressed by diverse immune cells and is upregulated during inflammation—including during toxin-mediated disease induced by C. difficile . This work highlights a mechanism by which C. difficile can use a host-derived nutrient that is generated during toxin-induced disease by an enzyme that has not previously been associated with infection. RNA-sequencing experiments determine that sorbitol, a metabolite produced by the host enzyme aldose reductase, is exploited by Clostridium difficile in its adaptation to inflammatory conditions in the gut.