Hypo-osmotic stress induces the epithelial alarmin IL-33 in the colonic barrier of ulcerative colitis

Epithelial alarmins are gaining interest as therapeutic targets for chronic infammation. The nuclear alarmin interleukin-33 (IL-33) is upregulated in the colonic mucosa of acute ulcerative colitis (UC) and may represent an early instigator of the infammatory cascade. However, it is not clear what signals drive the expression of IL-33 in the colonic mucosa, nor is the exact role of IL-33 elucidated. We established an ex vivo model using endoscopic colonic biopsies from healthy controls and UC patients. Colonic biopsies exposed to hypo-osmotic medium induced a strong nuclear IL-33 expression in colonic crypts in both healthy controls and UC biopsies. Mucosal IL33 mRNA was also signifcantly increased following hypo-osmotic stress in healthy controls compared to non-stimulated biopsies (fold change 3.9, p-value < 0.02). We observed a modest induction of IL-33 in response to TGF-beta-1 stimulation, whereas responsiveness to infammatory cytokines TNF and IFN-gamma was negligible. In conclusion our fndings indicate that epithelial IL-33 is induced by hypo-osmotic stress, rather than prototypic proinfammatory cytokines in colonic ex vivo biopsies. This is a novel fnding, linking a potent cytokine and alarmin of the innate immune system with cellular stress mechanisms and mucosal infammation

Prediction of long-term remission in patients following discontinuation of anti-TNF therapy in ulcerative colitis: a 10 year follow up study

Background - The long-term outcomes of Ulcerative colitis (UC) after discontinuation of biological therapy are largely unknown. There is also a lack of accurate and validated markers that can predict outcome after withdrawal accurately. The aims of this study were to describe the long-term outcomes in UC patients following cessation of anti-TNF therapy and explore potential biomarkers as an approach towards precision medicine. Methods - Seventy-five patients with moderate to severe UC treated to remission with anti-tumor necrosis factor (TNF) were included in the study. This is a follow-up of previously reported UC outcomes. The patients were categorized as either “Remission” or “Relapse”. The “Relapse” group was divided into subgroups determined by the highest treatment level needed to obtain remission the last 3 years of observation: non-biological therapy, biological therapy or colectomy. Remission were divided in long term remission (LTR), those using immunomodulating drugs (LTR + imids) and those using only 5-amino-salicylate (5-ASA) treatment (LTR) for the past 3 years. Analyses of mucosal gene expression by real-time PCR were performed. Results - The median (IQR) observation time of all patients included was 121 (111–137) months. Of the 75 patients, 46 (61%) did not receive biological therapy, including 23 (31%) in LTR ± imids. Of these 23 patients, 16 (21%) were defined as LTR with a median observation time of (IQR) 95 (77–113) months. In total 14 patients (19%) underwent colectomy during the 10 years after first remission. Mucosal TNF copies/µg mRNA  Conclusion - In this 10-year follow-up of UC of patients with moderate to severe disease, 61% of patients experience an altered phenotype to a milder disease course without need of biological therapy. Twenty-one percent of the patients were LTR without any medication except of 5-ASA. Mucosal TNF gene expression and IL1RL1- transcripts may be of clinical utility for long term prognosis in development of precision medicine in UC

Pharmacodynamic mechanisms behind a refractory state in inflammatory bowel disease

Background and aims - Biological therapy for inflammatory bowel disease is efficient in many cases but not all. The underlying molecular mechanisms behind non-response to biological therapy in inflammatory bowel disease are poorly described. Therefore, we aimed to characterize the mucosal cytokine transcript profile in non-immunogenic, non-responder patients with adequate trough level. Material and methods - Patients with ulcerative colitis (UC) (n = 21) and Crohn’s disease (CD) (n = 12) with non-response to biological therapy (anti-tumor necrosis factor (TNF) or vedolizumab) were included. Reference groups were A: untreated patients with UC or CD at debut of disease who had severe 1-year outcome, B: patients with UC or CD treated to endoscopic remission with biological agents, and C: healthy normal controls. Mucosal transcripts of TNF, interleukin (IL)17 and IL23 were measured by reverse transcription real-time quantitative polymerase chain reaction. Results Of the non-responders, 2 out of 12 CD and 1 out of 21 UC patients needed surgery during follow-up. Of the remaining non-responding patients, 8 out of 10 CD and 12 out of 20 UC patients switched biologic treatment. The remaining 2 CD and 8 UC patients continued treatment with the same biological agent with the addition of steroids, immunomodulators (AZA/MTX) and /or local steroids/5ASA. Twelve (8 UC/4 CD) out of 20 IBD patients were still non-responders after changing biological therapy to either anti-TNF (2), vedolizumab (9) or ustekinumab (1). The transcripts of IL17, IL23 and TNF were significantly upregulated in the non-response group compared to normal controls and patients in remission. In UC, 24% of the non-responders had normal mucosal TNF transcript indicating a non-TNF mediated inflammation. No obvious differences in gene expression were observed between primary and secondary non-responders, nor between anti-TNF and vedolizumab non-responders. Conclusions - Mucosal transcripts of IL17 and IL23 are highly associated with non-response to biological therapy, whereas some UC patients may also have a non-TNF mediated inflammatory pathway

Interleukin 33: a locally induced alarmin in the colonic mucosa of ulcerative colitis

Ulcerative colitis (UC) is a chronic inflammatory bowel disease involving the mucosal lining of the large bowel (colon and rectum). Common symptoms include bouts of diarrhoea, rectal bleeding and abdominal pain. The pathogenesis of UC is complex and multifactorial. This thesis investigated interleukin 33 (IL-33), an alarmin of the innate immune system. IL-33 is of interest as it is found to be upregulated in UC during active disease. IL-33 is also found to accumulate beneath mucosal ulcerations in UC suggesting a role in mucosal healing. We aimed to explore mediators associated with IL-33, inflammation and fibrosis in colonic biopsies from patients with acute and quiescent UC disease. We found mucosal mRNA IL33 to be raised in biopsies with UC compared to healthy controls. Immunostaining revealed IL-33 to be present in the epithelial barrier during active UC, but not in quiescent disease or healthy controls. Furthermore, a significant number of gene transcripts associated with fibrosis were found to be dysregulated in the UC mucosa and of interest for future research. To investigate IL-33 expression in the colonic epithelium, a human ex vivo model based on endoscopic biopsies was developed. Stimulation with hypo-osmotic stress induced a strong IL-33 signal in epithelial cells, linking IL-33 to a cellular stress response. In conclusion, IL-33 is an inducible nuclear factor in the colonic epithelium. In our studies we found epithelial IL-33 to be associated with active UC disease and hypo-osmotic stress. The use of a human explant model shows promise for further studies of inflammatory mediators in the colon

Mucosal gene transcription of ulcerative colitis in endoscopic remission

Aim/Objective: Ulcerative colitis (UC) is a chronic inflammatory bowel disease. In UC, a wide range of criteria are used for disease remission, with few studies investigating the differences between disease remission and normal control groups. This paper compares known inflammatory and healing mediators in the mucosa of UC in clinical remission and normal controls, in order to better describe the remission state. Method: Mucosal biopsies from 72 study participants (48 UC and 24 normal controls) were included from the Advanced Study of Inflammatory Bowel Disease (ASIB Study), Arctic University of Norway, Norway. Clinical remission was defined as Mayo clinical score ≤ 2, with endoscopic subscores of ≤ 1. Targeted gene transcription analyses were performed using hydrolysis probes and SYBR-green. Results: Among the mucosal transcripts examined, 10 genes were regulated in remission versus normal controls, 8 upregulated pro-inflammatory transcripts (IL1B, IL33, TNF, TRAF1, CLDN2, STAT1, STAT3 and IL13Ra2) and 2 downregulated (pro-inflammatory TBX21 and anti-inflammatory TGFB1). In total, 14 transcripts were regulated between the investigated groups. Several master transcription factors for T-cell development were upregulated in patients with Mayo endoscopic score of 1 in comparison to 0. Conclusions: The mucosa of UC in clinical and endoscopic remission differs from normal mucosa, suggesting a remaining dysregulation of inflammatory and wound healing mechanisms

Dynamics of the IL-33/ST2 network in the progression of human colorectal adenoma to sporadic colorectal cancer

Most sporadic colorectal cancers (CRCs) develop from preformed adenomas. Cytokines are involved in the transition from adenoma to CRC. Interleukin-33 (IL-33) is a newly discovered proinflammatory cytokine belonging to the IL-1 cytokine family and involved in the development of chronic inflammation and cancer. The aim of this study was to evaluate the dynamics of the IL-33/ST2 axis during the sequence of progression from normal colorectum to adenoma to carcinoma and to investigate the association of IL-33 and ST2 expression with clinicopathological parameters and prognosis. The results demonstrated that the levels of IL-33 and ST2 in adenomas (n = 50), determined by real-time PCR, were significantly higher than those of normal controls (n = 30); the levels of both IL-33/ST mRNA in CRCs (n = 50) were higher than in normal controls but lower than in adenomas. Further analysis revealed that the expression level of ST2 in CRCs was associated with tumor/node/metastasis (TNM) stage. The log-rank test showed that neither the IL-33 nor the ST2 expression level was correlated with overall survival in patients with CRC. The increased expression of IL-33/ST2 in adenomas and CRC tissues was confirmed by immunohistochemistry and was observed in both the tumor stromal cells and adenomatous/cancerous cells. Notably, increased densities of IL-33-positive and ST2-positive microvessels were found in the stroma of adenomas and CRCs. In conclusion, increased expression of the IL-33/ST2 axis along the colorectal adenoma–carcinoma sequence might be involved in the neoplastic transformation via the participation of this axis in the regulation of angiogenesis

Loss of interleukin 33 expression in colonic crypts- a potential marker for disease remission in ulcerative colitis

Interleukin 33 (IL-33) is a cytokine preferentially elevated in acute ulcerative colitis (UC), inferring a role in its pathogenesis. The role of IL-33 in intestinal inflammation is incompletely understood, with both pro-inflammatory and regulatory properties described. There are also conflicting reports on cellular sources and subcellular location of IL-33 in the colonic mucosa, justifying a closer look at IL-33 expression in well-defined clinical stages of UC. A total of 50 study participants (29 UC patients and 21 healthy controls) were included from a prospective cohort of inflammatory bowel disease patients treated to disease remission with infliximab, a tumour necrosis factor alpha (TNF) inhibitor. To our knowledge this is the first study examining mucosal IL-33 expression before and after anti-TNF therapy. In colonic mucosal biopsies we found a 3-fold increase in IL-33 gene expression comparing acute UC to healthy controls (p < 0.01). A significant reduction of IL33 between acute UC and disease remission was observed when TNF normalised in the mucosa (p = 0.02). Immunostaining revealed IL-33 in the nuclei of epithelial cells of scattered colonic crypts in acute disease, while at disease remission, IL-33 was undetectable, a novel finding suggesting that enterocyte-derived IL-33 is induced and maintained by inflammatory mediators

Discovery and validation of mucosal TNF expression combined with histological score-a biomarker for personalized treatment in ulcerative colitis

Background - There are no accurate markers that can predict clinical outcome in ulcerative colitis at time of diagnosis. The aim of this study was to explore a comprehensive data set to identify and validate predictors of clinical outcome in the first year following diagnosis. Methods - Treatment naive-patients with ulcerative colitis were included at time of initial diagnosis from 2004 to 2014, followed by a validation study from 2014 to 2018. Patients were treated according to clinical guidelines following a standard step-up regime. Patients were categorized according to the treatment level necessary to achieve clinical remission: mild, moderate and severe. The biopsies were assessed by Robarts histopathology index (RHI) and TNF gene transcripts. Results - We included 66 patients in the calibration cohort and 89 patients in the validation. Mucosal TNF transcripts showed high test reliability for predicting severe outcome in UC. When combined with histological activity (RHI) scores the test improved its diagnostic reliability. Based on the cut-off values of mucosal TNF and RHI scores from the calibration cohort, the combined test had still high reliability in the validation cohort (specificity 0.99, sensitivity 0.44, PPV 0.89, NPV 0.87) and a diagnostic odds-ratio (DOR) of 54. Conclusions - The combined test using TNF transcript and histological score at debut of UC can predict severe outcome and the need for anti-TNF therapy with a high level of precision. These validated data may be of great clinical utility and contribute to a personalized medical approach with the possibility of top-down treatment for selected patients