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Background: Phosphatase and tensin homolog (Pten) is capable of mediating microbe-induced immune responses in the gut. Thus, Pten deficiency in the intestine accelerates colitis development in Il10-/- mice. As some ambient pollutants inhibit Pten function and exposure to ambient pollutants may increase inflammatory bowel disease (IBD) incidence, it is of interest to examine how Pten inhibition could affect colitis development in genetically susceptible hosts., Methods: With human colonic mucosa biopsies from pediatric ulcerative colitis and non-IBD control subjects, we assessed the mRNA levels of the PTEN gene and the gene involved in IL10 responses. The data from the human tissues were corroborated by treating Il10-/-, Il10rb-/-, and wild-type C57BL/6 mice with Pten-specific inhibitor VO-OHpic. We evaluated the severity of mouse colitis by investigating the tissue histology and cytokine production. The gut microbiome was investigated by analyzing the 16S ribosomal RNA gene sequence with mouse fecal samples., Results: PTEN and IL10RB mRNA levels were reduced in the human colonic mucosa of pediatric ulcerative colitis compared with non-IBD subjects. Intracolonic treatment of the Pten inhibitor induced colitis in Il10-/- mice, characterized by reduced body weight, marked colonic damage, and increased production of inflammatory cytokines, whereas Il10rb-/- and wild-type C57BL/6 mice treated with the inhibitor did not develop colitis. Pten inhibitor treatment changed the fecal microbiome, with increased abundance of colitogenic bacteria Bacteroides and Akkermansia in Il10-/- mice., Conclusions: Loss of Pten function increases the levels of colitogenic bacteria in the gut, thereby inducing deleterious colitis in an Il10-deficient condition.

Objective: Chronic HIV-1 infection leads to widespread inflammation and immune dysregulation. The gastrointestinal mucosa, a primary site for HIV-1 replication, is thought to play a significant role in this response. MicroRNAs (miRs) are small noncoding RNAs that regulate gene expression, including immune activation and inflammation. Here we investigate miR expression and function in the colonic mucosa during HIV-1 infection., Design and Methods: Using miR profiling, we examined miR expression in the colonic mucosa of HIV-infected patients. These miRs were further parsed to identify those that most likely function in HIV-related inflammation. Using bioinformatics tools, we identified potential target genes which were confirmed using in-vitro functional testing., Results: We identified 12 miRs that were differentially expressed in the colonic mucosa of HIV-infected patients with high versus undetectable plasma viral concentrations. Of these, both miR-26a and miR-29a were downregulated in untreated HIV-1 infection, yet not in the colonic mucosa from inflammatory bowel disease. This downregulation occurs within the first hours after infection. These miRs were further shown to directly target IL-6 and STAT3, respectively, with similar changes confirmed in an ex-vivo explant infection model., Conclusion: miR-26a and miR-29a levels are decreased in the colonic mucosa during chronic HIV-1 infection, and this change may be initiated during acute infection. Both miRs de-repress the IL-6/STAT3 signaling pathway, which could contribute to increased inflammation during infection. These miRs may represent novel therapeutic targets for HIV-1-associated inflammation in the colonic mucosa.

Background & Aims: Persistent activation of the inflammatory response contributes to the development of inflammatory bowel diseases, which increase the risk of colorectal cancer. We aimed to identify microRNAs that regulate inflammation during the development of ulcerative colitis (UC) and progression to colitis-associated colon cancer (CAC)., Methods: We performed a quantitative polymerase chain reaction analysis to measure microRNAs in 401 colon specimens from patients with UC, Crohn's disease, irritable bowel syndrome, sporadic colorectal cancer, or CAC, as well as subjects without these disorders (controls); levels were correlated with clinical features and disease activity of patients. Colitis was induced in mice by administration of dextran sodium sulfate (DSS), and carcinogenesis was induced by addition of azoxymethane; some mice also were given an inhibitor of microRNA214 (miR214)., Results: A high-throughput functional screen of the human microRNAome found that miR214 regulated the activity of nuclear factor-κB. Higher levels of miR214 were detected in colon tissues from patients with active UC or CAC than from patients with other disorders or controls and correlated with disease progression. Bioinformatic and genome-wide profile analyses showed that miR214 activates an inflammatory response and is amplified through a feedback loop circuit mediated by phosphatase and tensin homolog (PTEN) and PDZ and LIM domain 2 (PDLIM2). Interleukin-6 induced signal transducer and activator of transcription 3 (STAT3)-mediated transcription of miR214. A miR214 chemical inhibitor blocked this circuit and reduced the severity of DSS-induced colitis in mice, as well as the number and size of tumors that formed in mice given azoxymethane and DSS. In fresh colonic biopsy specimens from patients with active UC, the miR214 inhibitor reduced inflammation by increasing levels of PDLIM2 and PTEN., Conclusions: Interleukin-6 up-regulates STAT3-mediated transcription of miR214 in colon tissues, which reduces levels of PDLIM2 and PTEN, increases phosphorylation of AKT, and activates nuclear factor-κB. The activity of this circuit correlates with disease activity in patients with UC and progression to colorectal cancer., (Copyright © 2015 AGA Institute. Published by Elsevier Inc. All rights reserved.)

Background & Aims: Altered levels and functions of microRNAs (miRs) have been associated with inflammatory bowel diseases (IBDs), although little is known about their roles in pediatric IBD. We investigated whether colonic mucosal miRs are altered in children with ulcerative colitis (UC)., Methods: We used a library of 316 miRs to identify those that regulate phosphorylation of signal transducer and activator of transcription 3 (STAT3) in NCM460 human colonocytes incubated with interleukin-6. Levels of miR-124 were measured by real-time polymerase chain reaction analysis of colon biopsies from pediatric and adult patients with UC and patients without IBD (controls), and of HCT-116 colonocytes incubated with 5-aza-2'-deoxycytidine (5-AZA). Methylation of the MIR124 promoter was measured by quantitative methylation-specific polymerase chain reaction., Results: Levels of phosphorylated STAT3 and the genes it regulates (encoding vascular endothelial growth factor (VEGF), BCL2, BCLXL, and matrix metallopeptidase 9 [MMP9]) were increased in pediatric patients with UC compared with control tissues. Overexpression of miR-124, let-7, miR-125, miR-26, or miR-101 reduced STAT3 phosphorylation by ≥ 75% in NCM460 cells; miR-124 had the greatest effect. miR-124 was down-regulated specifically in colon tissues from pediatric patients with UC and directly targeted STAT3 messenger RNA (mRNA). Levels of miR-124 were decreased, whereas levels of STAT3 phosphorylation increased in colon tissues from pediatric patients with active UC compared with those with inactive disease. In addition, levels of miR-124 and STAT3 were inversely correlated in mice with experimental colitis. Down-regulation of miR-124 in tissues from children with UC was attributed to hypermethylation of its promoter region. Incubation of HCT-116 colonocytes with 5-AZA up-regulated miR-124 and reduced levels of STAT3 mRNA., Conclusions: miR-124 appears to regulate the expression of STAT3. Reduced levels of miR-124 in colon tissues of children with active UC appear to increase expression and activity of STAT3, which could promote inflammation and the pathogenesis of UC in children., (Copyright © 2013 AGA Institute. Published by Elsevier Inc. All rights reserved.)