Circulating and Tissue-Resident CD4+ T Cells With Reactivity to Intestinal Microbiota Are Abundant in Healthy Individuals and Function Is Altered During Inflammation.

BACKGROUND & AIMS: Interactions between commensal microbes and the immune system are tightly regulated and maintain intestinal homeostasis, but little is known about these interactions in humans. We investigated responses of human CD4+ T cells to the intestinal microbiota. We measured the abundance of T cells in circulation and intestinal tissues that respond to intestinal microbes and determined their clonal diversity. We also assessed their functional phenotypes and effects on intestinal resident cell populations, and studied alterations in microbe-reactive T cells in patients with chronic intestinal inflammation. METHODS: We collected samples of peripheral blood mononuclear cells and intestinal tissues from healthy individuals (controls, n = 13-30) and patients with inflammatory bowel diseases (n = 119; 59 with ulcerative colitis and 60 with Crohn's disease). We used 2 independent assays (CD154 detection and carboxy-fluorescein succinimidyl ester dilution assays) and 9 intestinal bacterial species (Escherichia coli, Lactobacillus acidophilus, Bifidobacterium animalis subsp lactis, Faecalibacterium prausnitzii, Bacteroides vulgatus, Roseburia intestinalis, Ruminococcus obeum, Salmonella typhimurium, and Clostridium difficile) to quantify, expand, and characterize microbe-reactive CD4+ T cells. We sequenced T-cell receptor Vβ genes in expanded microbe-reactive T-cell lines to determine their clonal diversity. We examined the effects of microbe-reactive CD4+ T cells on intestinal stromal and epithelial cell lines. Cytokines, chemokines, and gene expression patterns were measured by flow cytometry and quantitative polymerase chain reaction. RESULTS: Circulating and gut-resident CD4+ T cells from controls responded to bacteria at frequencies of 40-4000 per million for each bacterial species tested. Microbiota-reactive CD4+ T cells were mainly of a memory phenotype, present in peripheral blood mononuclear cells and intestinal tissue, and had a diverse T-cell receptor Vβ repertoire. These cells were functionally heterogeneous, produced barrier-protective cytokines, and stimulated intestinal stromal and epithelial cells via interleukin 17A, interferon gamma, and tumor necrosis factor. In patients with inflammatory bowel diseases, microbiota-reactive CD4+ T cells were reduced in the blood compared with intestine; T-cell responses that we detected had an increased frequency of interleukin 17A production compared with responses of T cells from blood or intestinal tissues of controls. CONCLUSIONS: In an analysis of peripheral blood mononuclear cells and intestinal tissues from patients with inflammatory bowel diseases vs controls, we found that reactivity to intestinal bacteria is a normal property of the human CD4+ T-cell repertoire, and does not necessarily indicate disrupted interactions between immune cells and the commensal microbiota. T-cell responses to commensals might support intestinal homeostasis, by producing barrier-protective cytokines and providing a large pool of T cells that react to pathogens

Oncostatin M drives intestinal inflammation and predicts response to tumor necrosis factor–neutralizing therapy in patients with inflammatory bowel disease

Inflammatory bowel diseases (IBD), including Crohn's disease (CD) and ulcerative colitis (UC), are complex chronic inflammatory conditions of the gastrointestinal tract that are driven by perturbed cytokine pathways. Anti-tumor necrosis factor-α (TNF) antibodies are mainstay therapies for IBD. However, up to 40% of patients are nonresponsive to anti-TNF agents, which makes the identification of alternative therapeutic targets a priority. Here we show that, relative to healthy controls, inflamed intestinal tissues from patients with IBD express high amounts of the cytokine oncostatin M (OSM) and its receptor (OSMR), which correlate closely with histopathological disease severity. The OSMR is expressed in nonhematopoietic, nonepithelial intestinal stromal cells, which respond to OSM by producing various proinflammatory molecules, including interleukin (IL)-6, the leukocyte adhesion factor ICAM1, and chemokines that attract neutrophils, monocytes, and T cells. In an animal model of anti-TNF-resistant intestinal inflammation, genetic deletion or pharmacological blockade of OSM significantly attenuates colitis. Furthermore, according to an analysis of more than 200 patients with IBD, including two cohorts from phase 3 clinical trials of infliximab and golimumab, high pretreatment expression of OSM is strongly associated with failure of anti-TNF therapy. OSM is thus a potential biomarker and therapeutic target for IBD, and has particular relevance for anti-TNF-resistant patients

NOX1 loss-of-function genetic variants in patients with inflammatory bowel disease.

Genetic defects that affect intestinal epithelial barrier function can present with very early-onset inflammatory bowel disease (VEOIBD). Using whole-genome sequencing, a novel hemizygous defect in NOX1 encoding NAPDH oxidase 1 was identified in a patient with ulcerative colitis-like VEOIBD. Exome screening of 1,878 pediatric patients identified further seven male inflammatory bowel disease (IBD) patients with rare NOX1 mutations. Loss-of-function was validated in p.N122H and p.T497A, and to a lesser degree in p.Y470H, p.R287Q, p.I67M, p.Q293R as well as the previously described p.P330S, and the common NOX1 SNP p.D360N (rs34688635) variant. The missense mutation p.N122H abrogated reactive oxygen species (ROS) production in cell lines, ex vivo colonic explants, and patient-derived colonic organoid cultures. Within colonic crypts, NOX1 constitutively generates a high level of ROS in the crypt lumen. Analysis of 9,513 controls and 11,140 IBD patients of non-Jewish European ancestry did not reveal an association between p.D360N and IBD. Our data suggest that loss-of-function variants in NOX1 do not cause a Mendelian disorder of high penetrance but are a context-specific modifier. Our results implicate that variants in NOX1 change brush border ROS within colonic crypts at the interface between the epithelium and luminal microbes

Th1 and innate lymphoid cells accumulate in primary sclerosing cholangitis-associated inflammatory bowel disease

Background and Aims Primary sclerosing cholangitis [PSC] is an idiopathic chronic disorder of the hepatobiliary system associated with inflammatory bowel disease [IBD], mainly ulcerative colitis [UC]. Colitis in patients with PSC and UC [PSC-UC] exhibits characteristic features and is linked to increased colon cancer risk. Genetic studies have identified immune-related susceptibility genes that only partially overlap with those involved in IBD. These observations suggest that PSC-UC may represent a distinct form of IBD. It remains to be elucidated whether different immune mechanisms are involved in colitis in these patients. We aimed to evaluate systemic and intestinal T cell and innate lymphoid cell [ILC] responses, previously associated with IBD, in patients with PSC-UC compared with patients with UC and healthy controls. Methods Blood samples and colorectal biopsies were collected from patients with PSC-UC, patients with UC, and healthy controls. T cell and ILC phenotypes were analysed by multicolour flow cytometry. Results Chemokine receptor [CCR] profiling of circulating T cells showed decreased CCR6-CXCR3+ Th1 cells in PSC-UC, but increased CCR6-CCR4+ Th2 cells only in UC, whereas increased CCR6+CCR4+ Th17 cells were found in both patient groups compared with healthy controls. Increased frequencies of IFN-γ secreting T cells were found in the colon of patients with PSC-UC compared with UC. Interestingly, we observed accumulation of ILC in the colon in PSC-UC. Conclusions Our study suggests that PSC-UC represents a different immunological disorder from UC, characterised by increased intestinal Th1 and ILC responses. These results provide further evidence that PSC-UC may represent a distinct form of IBD

Th1 and innate lymphoid cells accumulate in primary sclerosing cholangitis-associated inflammatory bowel disease

Background and Aims Primary sclerosing cholangitis [PSC] is an idiopathic chronic disorder of the hepatobiliary system associated with inflammatory bowel disease [IBD], mainly ulcerative colitis [UC]. Colitis in patients with PSC and UC [PSC-UC] exhibits characteristic features and is linked to increased colon cancer risk. Genetic studies have identified immune-related susceptibility genes that only partially overlap with those involved in IBD. These observations suggest that PSC-UC may represent a distinct form of IBD. It remains to be elucidated whether different immune mechanisms are involved in colitis in these patients. We aimed to evaluate systemic and intestinal T cell and innate lymphoid cell [ILC] responses, previously associated with IBD, in patients with PSC-UC compared with patients with UC and healthy controls. Methods Blood samples and colorectal biopsies were collected from patients with PSC-UC, patients with UC, and healthy controls. T cell and ILC phenotypes were analysed by multicolour flow cytometry. Results Chemokine receptor [CCR] profiling of circulating T cells showed decreased CCR6-CXCR3+ Th1 cells in PSC-UC, but increased CCR6-CCR4+ Th2 cells only in UC, whereas increased CCR6+CCR4+ Th17 cells were found in both patient groups compared with healthy controls. Increased frequencies of IFN-γ secreting T cells were found in the colon of patients with PSC-UC compared with UC. Interestingly, we observed accumulation of ILC in the colon in PSC-UC. Conclusions Our study suggests that PSC-UC represents a different immunological disorder from UC, characterised by increased intestinal Th1 and ILC responses. These results provide further evidence that PSC-UC may represent a distinct form of IBD

Multicentre derivation and validation of a colitis-associated colorectal cancer risk prediction web tool.

OBJECTIVE: Patients with ulcerative colitis (UC) diagnosed with low-grade dysplasia (LGD) have increased risk of developing advanced neoplasia (AN: high-grade dysplasia or colorectal cancer). We aimed to develop and validate a predictor of AN risk in patients with UC with LGD and create a visual web tool to effectively communicate the risk. DESIGN: In our retrospective multicentre validated cohort study, adult patients with UC with an index diagnosis of LGD, identified from four UK centres between 2001 and 2019, were followed until progression to AN. In the discovery cohort (n=246), a multivariate risk prediction model was derived from clinicopathological features using Cox regression. Validation used data from three external centres (n=198). The validated model was embedded in a web tool to calculate patient-specific risk. RESULTS: Four clinicopathological variables were significantly associated with AN progression in the discovery cohort: endoscopically visible LGD >1 cm (HR 2.7; 95% CI 1.2 to 5.9), unresectable or incomplete endoscopic resection (HR 3.4; 95% CI 1.6 to 7.4), moderate/severe histological inflammation within 5 years of LGD diagnosis (HR 3.1; 95% CI 1.5 to 6.7) and multifocality (HR 2.9; 95% CI 1.3 to 6.2). In the validation cohort, this four-variable model accurately predicted future AN cases with overall calibration Observed/Expected=1.01 (95% CI 0.64 to 1.52), and achieved 100% specificity for the lowest risk group over 13 years of available follow-up. CONCLUSION: Multicohort validation confirms that patients with large, unresected, multifocal LGD and recent moderate/severe inflammation are at highest risk of developing AN. Personalised risk prediction provided via the Ulcerative Colitis-Cancer Risk Estimator (www.UC-CaRE.uk) can support treatment decision-making