Rho-kinase inhibitor Y-27632 downregulates LPS-induced IL-6 and IL-8 production via blocking p38 MAPK and NF-κB pathways in human gingival fibroblasts.

Abstract

Porphyromonas gingivalis lipopolysaccharide (LPS) plays a major role in the initiation and progression of chronic periodontitis. Human gingival fibroblasts (HGFs) interact with bacteria or bacterial products and trigger inflammatory signaling pathways that destroy periodontal tissues. RhoA regulates cytokine production in various cell types. This study investigated the role of Rho-kinase inhibitor Y-27632 in LPS-induced nuclear factor-kappa B (NF-κB) and p-38 mitogen-activated protein kinase (MAPK) activation, and inflammatory cytokine production in HGFs. Effects of Y-27632, SB203580 (p38 MAPK inhibitor), and BAY11-7082 (NF-κB inhibitor) were assessed in lipopolysaccharide (LPS)-treated HGFs. Cytotoxicity assays were used to determine the effect of the drugs on HGF viability. Enzyme-linked immunosorbent assays and quantitative real-time polymerase chain reaction were applied to evaluate the levels of interleukin (IL)-6, IL-8, and Toll-like receptors (TLRs). NF-κB and p38 MAPK pathway activation was detected by western blot and immunocytochemistry. P. gingivalis LPS at 5μg/mL, 10μM Y-27632, 10μM SB203580, and 5μM BAY11-7082 exhibited no toxicity in HGFs. LPS activated NF-κB and p38 MAPK by increasing degradation of IκBα and phosphorylation of IκBα, p65, and p38, and facilitating p65 translocation from the cytoplasm to nuclei. The activation of NF-κB and p38 MAPK induced overproduction of IL-6 and IL-8 at both mRNA and protein levels. However, Y-27632 attenuated LPS-induced NF-κB and p38 MAPK activation and inflammatory cytokine production. Rho-kinase inhibitor Y-27632 downregulates LPS-induced IL-6 and IL-8 production by blocking NF-κB and p38 MAPK activation in HGFs.