Inflammatory Bowel Diseases (IBD), represented by Crohn’s Disease (CD) and Ulcerative Colitis (UC), are associated with significant morbidity in western countries and with increasing incidence in the developing world. While analysis of the genome of IBD patients, especially through genome-wide association studies, has unraveled multiple pathways involved in IBD pathogenesis only part of IBD heritability has been explained by genetic studies. This has demonstrated that environmental factors also play a significant role in promoting intestinal inflammation, mostly through their effects in the composition of the microbiome. However, in order for microbial dysbiosis to result in uncontrolled intestinal inflammation, the intestinal barrier formed by intestinal epithelial cells and the innate immune system should also be compromised. Finally, activation of the immune system depends on the working balance between effector and regulatory cells present in the intestinal mucosa, which have also been shown to be dysregulated in this patient population. Therefore, IBD pathogenesis is a result of the interplay of genetic susceptibility, environmental impact on the microbiome that through a weakened intestinal barrier will lead to inappropriate intestinal immune activation. In this review, we will approach the mechanisms proposed to cause IBD from the genetic, environmental, intestinal barrier and the immunologic perspectives.

In a retrospective study of patients with pancreaticobiliary IgG4-RD, we found rituximab maintenance therapy prolongs remission. Relapses are uncommon among patients receiving maintenance therapy, but maintenance therapy may increase risk of infection. Patients with factors that predict relapse could be candidates for rituximab maintenance therapy.

Our cohort showed a low rate of immunogenicity to VDZ and an association between VTLs and CRP in CD but not in UC patients. No relationship between VTLs and MH was detected. Vedolizumab trough level measurements altered management in approximately three fourths of patients.

Climatic conditions are another factor that may interfere with the IR of Pseudomonas aeruginosa.

We described a case series of patients developing de-novo IBD after bariatric surgery. There appears to be a numerically higher incidence of Crohn's disease in this population. Confirmation of causality is required in larger patient cohorts.

Background An association between inflammatory bowel disease (IBD) and obesity has been observed. Little is known about the effect of weight loss on IBD course. Our aim was to determine the impact of bariatric surgery on long-term clinical course of obese patients with IBD, either Crohn's disease (CD) or ulcerative colitis (UC). Methods Patients with IBD who underwent bariatric surgery subsequent to IBD diagnosis were identified from 2 tertiary IBD centers. Complications after bariatric surgery were recorded. Patients were matched 1:1 for age, sex, IBD subtype, phenotype, and location to patients with IBD who did not undergo bariatric surgery. Controls started follow-up at a time point in their disease similar to the disease duration in the matched case at the time of bariatric surgery. Inflammatory bowel disease medication usage and disease-related complications (need for corticosteroids, hospitalizations, and surgeries) among cases and controls were compared. Results Forty-seven patients met inclusion criteria. Appropriate matches were found for 25 cases. Median follow-up among cases (after bariatric surgery) and controls was 7.69 and 7.89 years, respectively. Median decrease in body mass index after bariatric surgery was 12.2. Rescue corticosteroid usage and IBD-related surgeries were numerically less common in cases than controls (24% vs 52%; odds ratio [OR], 0.36; 95% confidence interval [CI], 0.08–1.23; 12% vs 28%; OR, 0.2; 95% CI, 0.004–1.79). Two cases and 1 control were able to discontinue biologics during follow-up. Conclusions Inflammatory bowel disease patients with weight loss after bariatric surgery had fewer IBD-related complications compared with matched controls. This observation requires validation in a prospective study design.

Background Pivotal trials have shown that ustekinumab (UST) is effective in ulcerative colitis (UC). However, the population included in these trials do not always represent the cohort of patients treated in the “real world”. In this study, we aimed to describe the effectiveness and safety of UST in a clinical cohort of patients with UC Methods We performed a multi-center cohort study and included patients with active UC starting UST. Variables collected included demographics, previous and current UC medications, disease activity (measured using partial and endoscopic Mayo score [PMS and EMS]) at 8 weeks, 6 months and end of follow-up. We also abstracted UST drug level and anti-UST antibodies (AUA), albumin and C-reactive protein levels. Primary outcomes were clinical response at week 8 defined as a reduction of 3 points in the PMS or PMS<2. Secondary outcomes were clinical remission defined as a PMS <2 and endoscopic remission defined as a MES ≤1, and the development of an adverse event (AE) attributed to UST. Results Ninety-five patients were included with a median age of 42 years (IQR:32-57) and 53 (56%) were female. Median follow-up was 5 months (IQR:2.2-7.4). Only 4 (4.3%) were naïve to biologics or tofacitinib and 62 (66%) had previous exposure to at least 2 other biologics. No variables were found to be associated with response at week 8 (Figure 2). Those patients who responded at week 8 had higher median albumin levels vs those who did not (median of 4.4 [IQR: 4.1-4.6] vs 4.1 g/dL [IQR:3.8-4.3]; p=0.02). There were no differences in baseline CRP levels (1mg/dL [IQR:0.6-2.8] vs 0.6 mg/dL [0.3-1.5]; p=0.06). Among the 33 patients who had follow-up endoscopic assessment, 7 (21.2%) had achieved endoscopic remission and 4 (12%) achieved histologic remission. Median UST level was 4.1 mcg/ml (IQR:2.5-5.1) and no patients had detectable AUA. Five patients underwent colectomy (5.3%). Only 6 patients (6.6%) presented with an AE (all minor that included, rash, headaches, arthralgias and infection). Conclusion In a population enriched with refractory UC, UST was well tolerated and induce response and remission in a significant number of patients. The rate of response was lower in obese patients and those with extensive colitis but was not associated with previous exposure to biologics and/or tofacitinib. Larger studies with a longer follow-up are warranted. Figure 1: Rates of clinical response and remission in patients with UC receiving ustekinumab Figure 2: Association between several baseline characteristics and response to ustekinumab in UC

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