LncRNA PFAL suppresses TNF-α-induced inflammation by upregulating miR-18a in WI-38 cells

Purpose: Pneumonia is a serious respiratory disease among children with high mortality and morbidity all over the world. Long non-coding RNAs have been proven to play a vital role in many inflammatory diseases including pneumonia. In the present study, the protective impact of lncRNA PFAL on cell viability, cell apoptosis and secretion of inflammatory cytokines, as well as the underlying molecular mechanism in TNF-α-induced inflammatory injury model of pneumonia were investigated.Methods: WI-38 cell line was treated with 20 ng/ml TNF-α to establish an inflammatory injury model of pneumonia. LncRNA PFAL or miR-18a was up- or down-regulated in the WI-38 cells by transfection procedure. Cell viability was assessed using CCK-8 assay, while the rate of cell apoptosis was measured by utilizing flow cytometry. The mRNA expression levels of lncRNA PFAL, miR-18a, apoptosis-related and JNK pathway genes were determined with RT-qPCR. Moreover, the production of inflammatory cytokines such as IL-6 and MCP-1 were detected by using Western blot analysis.Results: The results indicated that cell viability was significantly (P<0.05) reduced, while the rate of cell apoptosis was increased in the TNF-α-induced WI-38 cells. Also, TNF-α treatment enhanced the expression of inflammatory cytokines that included IL-6 and MCP-1 in WI-38 cells. Overexpression of PFAL suppressed the injury induced by TNF-α and miR-18a was positively regulated by PFAL. Moreover, the inhibition of miR-18a weakens the effect of PFAL overexpression in TNF-α-induced cell injury. Furthermore, PFAL and miR-18a were involved in the regulation of JNK pathway.Conclusion: Overexpression of PFAL suppresses TNF-α-induced WI-38 cell injury by up-regulating miR-18a via the inactivation of JNK signaling pathway. Keywords: Inflammation, JNK pathway, miR-18a, PFAL, Pneumonia, TNF-α