MicroRNA-19b alleviates lipopolysaccharide-induced inflammatory injury in human intestinal cells by up-regulation of Runx3.

Objective: Ulcerative colitis (UC) is an unexplained inflammatory disease in bowel. Some studies reported that microRNA-19b (miR-19b) was closely related to cell inflammatory response. We aimed to explore the molecular mechanism of miR-19b on lipopolysaccharide (LPS)-induced human intestinal cell inflammatory injury. Materials and

Methods: Caco2 cells were treated with 10 ng/ml LPS to induce inflammatory injury. The expression of miR-19b and runt-related transcription factor 3 (Runx3) was changed in Caco2 cells by cell transfection. Then, the viability, apoptosis and pro-inflammatory factors expressions of transfected cells were assessed using trypan blue exclusion assay, flow cytometry, qRT-PCR, Western blotting and enzyme-linked immunosorbent assay (ELISA), respectively, after LPS treatment. At last, the expressions of key factors involved in nuclear factor kappa B (NF-κB) and phosphatidylinositol 3-kinase/protein kinase 3 (PI3K/AKT) pathways were evaluated using Western blotting.

Results: LPS significantly induced Caco2 cell inflammatory injury, down-regulated miR-19b expression and activated NF-κB and PI3K/AKT pathways. Suppression of miR-19b enhanced the LPS-induced Caco2 cell inflammatory injury, as well as NF-κB and PI3K/AKT pathways activation. Overexpression of miR-19b had opposite effects. In addition, miR-19b regulated the expression of Runx3 in Caco2 cells. Overexpression of Runx3 reversed the miR-19b knockdown-induced Caco2 cell viability inhibition, apoptosis enhancement, inflammatory factors expressions and NF-κB and PI3K/AKT signaling pathways activation.

Conclusions: Our study demonstrated that miR-19b alleviated LPS-induced Caco2 cell inflammatory injury via up-regulation of Runx3 and deactivation of NF-κB and PI3K/AKT signaling pathways.