Abnormal levels of microRNA (miR)-155, which regulate inflammation and immune responses, have been demonstrated in the colonic mucosa of patients with inflammatory bowel diseases (IBD), although its role in disease pathophysiology is unknown. We investigated the role of miR-155 in the acquisition and maintenance of an activated phenotype by intestinal myofibroblasts (IMF), a key cell population contributing to mucosal damage in IBD. IMF were isolated from colonic biopsies of healthy controls, ulcerative colitis (UC) and Crohn's disease (CD) patients. MiR-155 in IMF was quantified by quantitative reverse transcription-PCR in basal condition and following exposure to TNF-alpha, interleukin (IL)-1beta, lipopolysaccharide (LPS) or TGF-beta1. The effects of miR-155 mimic or inhibitor transfection on cytokine release and suppressor of cytokine signaling 1 (SOCS1) expression were assessed by enzyme-linked immunosorbent assay and western blot, respectively. Regulation of the target gene SOCS1 expression by miR-155 was assessed using luciferase reporter construct. We found that miR-155 was significantly upregulated in UC as compared with control- and CD-derived IMF. Moreover, TNF-alpha and LPS, but not TGF-beta1 and IL-1beta, significantly increased miR-155 expression in IMF. Ectopic expression of miR-155 in control IMF augmented cytokines release, whereas it downregulated SOCS1 expression. MiR-155 knockdown in UC-IMF reduced cytokine production and enhanced SOCS1 expression. Luciferase reporter assay demonstrated that miR-155 directly targets SOCS1. Moreover, silencing of SOCS1 in control IMF significantly increased IL-6 and IL-8 release. In all, our data suggest that inflammatory mediators induce miR-155 expression in IMF of patients with UC. By downregulating the expression of SOCS1, miR-155 wires IMF inflammatory phenotype.
Adult ; Aged ; Cells, Cultured ; Colitis, Ulcerative/*genetics/immunology/*pathology ; Cytokines/immunology ; Female ; *Gene Expression Regulation ; Humans ; Intestinal Mucosa/immunology/metabolism/pathology ; Male ; MicroRNAs/*genetics ; Middle Aged ; Myofibroblasts/immunology/metabolism/*pathology ; Suppressor of Cytokine Signaling Proteins/*genetics ; Tumor Necrosis Factor-alpha/immunology ; Up-Regulation ; Young Adult

Abnormal levels of microRNA (miR)-155, which regulate inflammation and immune responses, have been demonstrated in the colonic mucosa of patients with inflammatory bowel diseases (IBD), although its role in disease pathophysiology is unknown. We investigated the role of miR-155 in the acquisition and maintenance of an activated phenotype by intestinal myofibroblasts (IMF), a key cell population contributing to mucosal damage in IBD. IMF were isolated from colonic biopsies of healthy controls, ulcerative colitis (UC) and Crohn's disease (CD) patients. MiR-155 in IMF was quantified by quantitative reverse transcription-PCR in basal condition and following exposure to TNF-alpha, interleukin (IL)-1beta, lipopolysaccharide (LPS) or TGF-beta1. The effects of miR-155 mimic or inhibitor transfection on cytokine release and suppressor of cytokine signaling 1 (SOCS1) expression were assessed by enzyme-linked immunosorbent assay and western blot, respectively. Regulation of the target gene SOCS1 expression by miR-155 was assessed using luciferase reporter construct. We found that miR-155 was significantly upregulated in UC as compared with control- and CD-derived IMF. Moreover, TNF-alpha and LPS, but not TGF-beta1 and IL-1beta, significantly increased miR-155 expression in IMF. Ectopic expression of miR-155 in control IMF augmented cytokines release, whereas it downregulated SOCS1 expression. MiR-155 knockdown in UC-IMF reduced cytokine production and enhanced SOCS1 expression. Luciferase reporter assay demonstrated that miR-155 directly targets SOCS1. Moreover, silencing of SOCS1 in control IMF significantly increased IL-6 and IL-8 release. In all, our data suggest that inflammatory mediators induce miR-155 expression in IMF of patients with UC. By downregulating the expression of SOCS1, miR-155 wires IMF inflammatory phenotype.
Adult ; Aged ; Cells, Cultured ; Colitis, Ulcerative/*genetics/immunology/*pathology ; Cytokines/immunology ; Female ; *Gene Expression Regulation ; Humans ; Intestinal Mucosa/immunology/metabolism/pathology ; Male ; MicroRNAs/*genetics ; Middle Aged ; Myofibroblasts/immunology/metabolism/*pathology ; Suppressor of Cytokine Signaling Proteins/*genetics ; Tumor Necrosis Factor-alpha/immunology ; Up-Regulation ; Young Adult

BACKGROUNDUlcerative colitis (UC) is associated with differential expression of genes involved in inflammation and tissue remodeling, including FOXO3a, which encodes a transcription factor known to promote inflammation in several tissues. However, FOXO3a expression in tissues affected by UC has not been examined. This study investigated the effects of FOXO3a on UC pathogenesis.

METHODSFOXO3a expression, in 23 patients with UC and in HT29 cells treated with tumor necrosis factor-α (TNF-α) for various durations, was detected by quantitative real-time polymerase chain reaction and Western blotting analysis. Enzyme-linked immunosorbent assay was used to quantify interleukin (IL)-8 expression in FOXO3a-silenced HT29 cells treated with TNF-α for various durations.

RESULTSThe messenger RNA and protein expression of FOXO3a were significantly lower in UC tissues than those in normal subjects (P < 0.01). TNF-α treatment for 0, 0.5, 1, 6, and 24 h induced FOXO3 degradation in HT29 cells. FOXO3a silencing increased IL-8 levels in HT29 cells treated with TNF-α for 6 h (P < 0.05).

CONCLUSIONFOXO3a may play an important role in the intestinal inflammation of patients with UC.

Adult ; Blotting, Western ; Colitis, Ulcerative ; immunology ; metabolism ; pathology ; Enzyme-Linked Immunosorbent Assay ; Female ; Forkhead Box Protein O3 ; genetics ; metabolism ; HT29 Cells ; Humans ; Inflammation ; immunology ; metabolism ; pathology ; Interleukin-8 ; metabolism ; Intestines ; immunology ; metabolism ; pathology ; Male ; Middle Aged ; Real-Time Polymerase Chain Reaction ; Tumor Necrosis Factor-alpha ; metabolism