miR-24 is elevated in ulcerative colitis patients and regulates intestinal epithelial barrier function

Inflammatory bowel disease is characterized by high levels of inflammation and loss of barrier integrity in the colon. The intestinal barrier is a dynamic network of proteins that encircle intestinal epithelial cells. miRNAs regulate protein-coding genes. In this study, miR-24 was found to be elevated in colonic biopsies and blood samples from ulcerative colitis (UC) patients compared with healthy controls. In the colon of UC patients, miR-24 is localized to intestinal epithelial cells, which prompted an investigation of intestinal epithelial barrier function. Two intestinal epithelial cell lines were used to study the effect of miR-24 overexpression on barrier integrity. Overexpression of miR-24 in both cell lines led to diminished transepithelial electrical resistance and increased dextran flux, suggesting an effect on barrier integrity. Overexpression of miR-24 did not induce apoptosis or affect cell proliferation, suggesting that the effect of miR-24 on barrier function was due to an effect on cell–cell junctions. Although the tight junctions in cells overexpressing miR-24 appeared normal, miR-24 overexpression led to a decrease in the tight junction–associated protein cingulin. Loss of cingulin compromised barrier formation; cingulin levels negatively correlated with disease severity in UC patients. Together, these data suggest that miR-24 is a significant regulator of intestinal barrier that may be important in the pathogenesis of UC

MicroRNA-24 and Ulcerative Colitis: Expression, Functionality, and Therapeutic Potential

Ulcerative Colitis is a chronic inflammatory disease of the gastrointestinal tract that affects over 1 million people in the United States resulting in $2.7 billion in healthcare costs each year. Ulcerative Colitis is characterized by chronic, uncontrolled inflammation localized to the colon and rectum which leads to debilitating symptoms and significant complications. This disease has limited treatment options, with 20-25% of patients needing surgical intervention to alleviate symptoms. Many researchers are focused on finding new therapeutic targets for Ulcerative Colitis to aid those patients for whom the current treatments are not effective. One potential target, microRNAs, are small, single-stranded RNAs with the ability to repress gene expression. Many microRNAs are implicated in the pathophysiology of different diseases, including Ulcerative Colitis. MicroRNA-24 is a specific microRNA that is associated with multiple cancers, cardiovascular disease, and inflammatory activity. Here, we describe the expression, function, and therapeutic potential for microRNA-24 in Ulcerative Colitis. Our data reveal that microRNA-24 is elevated in Ulcerative Colitis and disrupts intestinal barrier function by targeting the tight junction protein cingulin. Furthermore, microRNA-24 inhibition in mouse models of colitis impaired epithelial restitution during the recovery period. We discovered that microRNA-24 robustly regulates apoptosis in the intestinal epithelium. Consequently, microRNA-24 inhibition promoted cell death which hindered mucosal repair. Taken together, this work highlights microRNA-24 as a relevant factor in the pathogenesis of Ulcerative Colitis that deserves further study to unlock its utility as a therapeutic target

MicroRNA-24 and Ulcerative Colitis: Expression, Functionality, and Therapeutic Potential

Ulcerative Colitis is a chronic inflammatory disease of the gastrointestinal tract that affects over 1 million people in the United States resulting in $2.7 billion in healthcare costs each year. Ulcerative Colitis is characterized by chronic, uncontrolled inflammation localized to the colon and rectum which leads to debilitating symptoms and significant complications. This disease has limited treatment options, with 20-25% of patients needing surgical intervention to alleviate symptoms. Many researchers are focused on finding new therapeutic targets for Ulcerative Colitis to aid those patients for whom the current treatments are not effective. One potential target, microRNAs, are small, single-stranded RNAs with the ability to repress gene expression. Many microRNAs are implicated in the pathophysiology of different diseases, including Ulcerative Colitis. MicroRNA-24 is a specific microRNA that is associated with multiple cancers, cardiovascular disease, and inflammatory activity. Here, we describe the expression, function, and therapeutic potential for microRNA-24 in Ulcerative Colitis. Our data reveal that microRNA-24 is elevated in Ulcerative Colitis and disrupts intestinal barrier function by targeting the tight junction protein cingulin. Furthermore, microRNA-24 inhibition in mouse models of colitis impaired epithelial restitution during the recovery period. We discovered that microRNA-24 robustly regulates apoptosis in the intestinal epithelium. Consequently, microRNA-24 inhibition promoted cell death which hindered mucosal repair. Taken together, this work highlights microRNA-24 as a relevant factor in the pathogenesis of Ulcerative Colitis that deserves further study to unlock its utility as a therapeutic target

Hyaluronan’s Role in Fibrosis: A Pathogenic Factor or a Passive Player?

Fibrosis is a debilitating condition that can lead to impairment of the affected organ’s function. Excessive deposition of extracellular matrix (ECM) molecules is characteristic of most fibrotic tissues. Fibroblasts activated by cytokines or growth factors differentiate into myofibroblasts that drive fibrosis by depositing ECM molecules, such as collagen, fibronectin, and connective tissue growth factor. Transforming growth factor-β (TGF-β) is one of the major profibrotic cytokines which promotes fibrosis by signaling abnormal ECM regulation. Hyaluronan (HA) is a major ECM glycosaminoglycan that is regulated by TGF-β and whose role in fibrosis is emerging. Aside from its role as a hydrating, space filling polymer, HA regulates different cellular functions and is known to have a role in wound healing and inflammation. Importantly, HA deposition is increased in multiple fibrotic diseases. In this review we highlight studies that link HA to fibrosis and discuss what is known about the role of HA, its receptors, and its anabolic and catabolic enzymes in different fibrotic diseases

Crohnâs Disease Fibroblasts Overproduce the Novel Protein KIAA1199 to Create Proinflammatory Hyaluronan FragmentsSummary

Background & Aims: Crohnâs Disease (CD) is a chronic inflammatory disease of the gastrointestinal tract. Fibrosis, a serious complication of CD, occurs when activated intestinal fibroblasts deposit excessive amounts of extracellular matrix (ECM) in affected areas. A major component of the ECM is high-molecular-weight hyaluronan (HA) that, when depolymerized to low-molecular-weight fragments, becomes proinflammatory and profibrotic. Mechanisms for HA degradation are incompletely understood, but the novel protein KIAA1199 recently was discovered to degrade HA. We hypothesized that KIAA1199 protein is increased in CD colon fibroblasts and generates HA fragments that foster inflammation and fibrosis. Methods: Fibroblasts were isolated from explants of surgically resected colon tissue from CD and nonâinflammatory bowel disease control (ND) patients. Protein levels and tissue distribution of KIAA1199 were assessed by immunoblot and immunostaining, and functional HA degradation was measured biochemically. Results: Increased levels of KIAA1199 protein were produced and deposited in the ECM by cultured CD fibroblasts compared with controls. Treatment of fibroblasts with the proinflammatory cytokine interleukin (IL) 6 increased deposition of KIAA1199 in the ECM. CD fibroblasts also produce significantly higher levels of IL6 compared with controls, and antibody blockade of IL6 receptors in CD colon fibroblasts decreased the level of KIAA1199 protein in the ECM. Colon fibroblasts degrade HA, however, small interfering RNA silencing of KIAA1199 abrogated that ability. Conclusions: CD fibroblasts produce increased levels of KIAA1199 primarily through an IL6-driven autocrine mechanism. This leads to excessive degradation of HA and the generation of proinflammatory HA fragments, which contributes to maintenance of gut inflammation and fibrosis. Keywords: Crohnâs Disease, Fibrosis, Hyaluronan, KIAA119

The Colonic Mucosal MicroRNAs, MicroRNA-219a-5p, and MicroRNA-338-3p Are Downregulated in Irritable Bowel Syndrome and Are Associated With Barrier Function and MAPK Signaling

Background & aimsAlterations in microRNA (miRNA) and in the intestinal barrier are putative risk factors for irritable bowel syndrome (IBS). We aimed to identify differentially expressed colonic mucosal miRNAs, their targets in IBS compared to healthy controls (HCs), and putative downstream pathways.MethodsTwenty-nine IBS patients (15 IBS with constipation [IBS-C], 14 IBS with diarrhea [IBS-D]), and 15 age-matched HCs underwent sigmoidoscopy with biopsies. A nCounter array was used to assess biopsy specimen-associated miRNA levels. A false discovery rate (FDR) < 10% was considered significant. Real-time polymerase chain reaction (PCR) was used to validate differentially expressed genes. To assess barrier function, trans-epithelial electrical resistance (TEER) and dextran flux assays were performed on Caco-2 intestinal epithelial cells that were transfected with miRNA-inhibitors or control inhibitors. Protein expression of barrier function associated genes was confirmed using western blots.ResultsFour out of 247 miRNAs tested were differentially expressed in IBS compared to HCs (FDR < 10%). Real-time PCR validation suggested decreased levels of miR-219a-5p and miR-338-3p in IBS (P = .026 and P = .004), and IBS-C (P = .02 and P = .06) vs. HCs as the strongest associations. Inhibition of miR-219a-5p resulted in altered expression of proteasome/barrier function genes. Functionally, miR-219a-5p inhibition enhanced the permeability of intestinal epithelial cells as TEER was reduced (25-50%, P < .05) and dextran flux was increased (P < .01). Additionally, inhibition of miR-338-3p in cells caused alterations in the mitogen-activated protein kinase (MAPK) signaling pathway genes.ConclusionTwo microRNAs that potentially affect permeability and visceral nociception were identified to be altered in IBS patients. MiR-219a-5p and miR-338-3p potentially alter barrier function and visceral hypersensitivity via neuronal and MAPK signaling and could be therapeutic targets in IBS