Lipopolysaccharide-induced inflammation in human peritoneal mesothelial cells is controlled by ERK1/2-CDK5-PPARγ axis

摘要

Background: Peritonitis is a common complication in which the peritoneum becomes inflamed. Peroxisome proliferator-activated receptor (PPAR)gamma agonists and extracellular signal-regulated kinases 1/2 (ERK1/2) inactivation have been found to restore damage caused by lipopolysaccharide-induced (LPS) inflammation. This study aimed to investigate the association between PPAR gamma and ERK1/2 in LPS-induced inflammation in peritonitis. @@@ Methods: Human peritoneal mesothelial cells were maintained in Dulbecco's Modified Eagle Medium and treated with LPS under a series of different concentrations and treatment times. Cellular interleukins-1 beta eta (IL-1 beta), cellular interleukins-6 (IL-6), cellular interleukins-12 (IL-12) were measured by enzyme-linked immunosorbent assay (ELISA) assay. Expression or activation of cyclin-dependent kinase (CDK)5, ERK1/2, and PPAR gamma was detected using quantitative real-time PCR and/or western blot. @@@ Results: LPS induced dose- and time-dependent increments in the cellular IL-1 beta, IL-6, and IL-12 contents, cyclin-dependent kinase 5 (CDK5) expression, and PPAR gamma(Ser273) phosphorylation. Treatment with 1 mu g/mL LPS for 12 hours was the optimal experimental design for inflammation stimulation. The concentration of LPS over 1 mu g/mL or treatment more than 12 hours reduced the inflammatory status. LPS stimulation also activated ERK1/2 and increased its interaction with CDK5. Further, ERK1/2 inhibition by AZD0364 prevented IL-1 beta, IL-6, IL-12, and CDK5 expression, as well as activation of ERK1/2 and phosphorylation of PPAR gamma, induced by LPS. Knockdown of CDK5 using its siRNA caused similar changes as AZD0364, minus ERK1/2 inactivation. @@@ Conclusions: Our results suggested that LPS-induced inflammation in human peritoneal mesothelial cells can be partly suppressed by inhibiting the ERK1/2/CDK5/PPAR gamma axis.

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