Predictors of irritable bowel syndrome-like symptoms in quiescent inflammatory bowel disease.

BACKGROUND: Many patients with quiescent inflammatory bowel disease (IBD) suffer from irritable bowel syndrome (IBS)-like symptoms. Although these symptoms cause significant reductions in quality of life, evidence-based treatments are lacking as risk factors and pathophysiology of these symptoms are not clearly defined. We aimed to identify risk factors for development of IBS-like symptoms in IBD patients with quiescent disease. METHODS: We performed a single-center retrospective cohort study of adults with IBD from 2015 to 2021. Quiescent IBD was defined by a fecal calprotectin level <250 µg/g of stool or endoscopic evidence of quiescent disease. Cox regression was performed to identify variables that were independently associated with the incident development of IBS-like symptoms in IBD patients. KEY RESULTS: A total of 368 IBD patients were included for analysis, including 278 patients with UC and 88 with Crohn's disease. 15.5% of quiescent IBD patients developed IBS symptoms, with an incidence rate of (95% CI 48.0-82.0) 63.3 per 1000 person-years. In the multivariate model, mood disorders (including anxiety and depression) and Crohn's disease were associated with increased risk for developing IBS symptoms. Male sex and higher iron levels conferred lower risk for developing IBS symptoms. Results from the multivariable model were similar in sensitivity analysis with quiescent IBD defined by fecal calprotectin level <150 mcg/g. CONCLUSIONS & INFERENCES: Mood disorder and Crohn's disease were positively associated with IBS-like symptoms in quiescent IBD, whereas male sex and iron levels were protective. Our results were robust to different fecal calprotectin levels, arguing against inflammation as a mechanism for IBS-like symptoms. This data suggests noninflammatory mechanisms may be important in the pathogenesis of IBS-like symptoms in quiescent IBD. Future work may address whether modifying these risk factors may alter disease course.

Mechanism of the switch from NO to H2O2 in endothelium-dependent vasodilation in diabetes.

Coronary microvascular dysfunction is prevalent among people with diabetes and is correlated with cardiac mortality. Compromised endothelial-dependent dilation (EDD) is an early event in the progression of diabetes, but its mechanisms remain incompletely understood. Nitric oxide (NO) is the major endothelium-dependent vasodilatory metabolite in the healthy coronary circulation, but this switches to hydrogen peroxide (H2O2) in coronary artery disease (CAD) patients. Because diabetes is a significant risk factor for CAD, we hypothesized that a similar NO-to-H2O2 switch would occur in diabetes. Vasodilation was measured ex vivo in isolated coronary arteries from wild type (WT) and microRNA-21 (miR-21) null mice on a chow or high-fat/high-sugar diet, and B6.BKS(D)-Leprdb/J (db/db) mice using myography. Myocardial blood flow (MBF), blood pressure, and heart rate were measured in vivo using contrast echocardiography and a solid-state pressure sensor catheter. RNA from coronary arteries, endothelial cells, and cardiac tissues was analyzed via quantitative real-time PCR for gene expression, and cardiac protein expression was assessed via western blot analyses. Superoxide was detected via electron paramagnetic resonance. (1) Ex vivo coronary EDD and in vivo MBF were impaired in diabetic mice. (2) Nω-Nitro-L-arginine methyl ester, an NO synthase inhibitor (L-NAME), inhibited ex vivo coronary EDD and in vivo MBF in WT. In contrast, polyethylene glycol-catalase, an H2O2 scavenger (Peg-Cat), inhibited diabetic mouse EDD ex vivo and MBF in vivo. (3) miR-21 was upregulated in diabetic mouse endothelial cells, and the deficiency of miR-21 prevented the NO-to-H2O2 switch and ameliorated diabetic mouse vasodilation impairments. (4) Diabetic mice displayed increased serum NO and H2O2, upregulated mRNA expression of Sod1, Sod2, iNos, and Cav1, and downregulated Pgc-1α in coronary arteries, but the deficiency of miR-21 reversed these changes. (5) miR-21-deficient mice exhibited increased cardiac PGC-1α, PPARα and eNOS protein and reduced endothelial superoxide. (6) Inhibition of PGC-1α changed the mRNA expression of genes regulated by miR-21, and overexpression of PGC-1α decreased the expression of miR-21 in high (25.5 mM) glucose treated coronary endothelial cells. Diabetic mice exhibit a NO-to-H2O2 switch in the mediator of coronary EDD, which contributes to microvascular dysfunction and is mediated by miR-21. This study represents the first mouse model recapitulating the NO-to-H2O2 switch seen in CAD patients in diabetes.