Lutein inhibits IL-6 expression by inducing PPAR-γ activation and SOCS3 expression in cerulein-stimulated pancreatic acinar cells

Acute pancreatitis is a severe inflammatory disease of the pancreas. In experimental acute pancreatitis, cerulein induces the expression of interleukin-6 (IL-6) by activating Janus kinase (JAK) 2/signal transducer and activator of transcription (STAT) 3 in pancreatic acinar cells. Ligands of peroxisome proliferator activated receptor-γ (PPAR-γ) and suppressor of cytokine signaling (SOCS) 3 inhibit IL-6 expression by suppressing JAK2/STAT3 in cerulein-stimulated pancreatic acinar AR42J cells. Lutein, an oxygenated carotenoid, upregulates and activates PPAR-γ to regulate inflammation in a renal injury model. The present study aimed to determine whether lutein activated PPAR-γ and induced SOCS3 expression in unstimulated AR42J cells, and whether lutein inhibited activation of JAK2/STAT3 and IL-6 expression via activation of PPAR-γ and SOCS3 expression in cerulein-stimulated AR42J cells. The anti-inflammatory mechanism of lutein was determined using reverse transcription-quantitative PCR, western blot analysis and enzyme-linked immunosorbent assay in AR42J cells stimulated with or without cerulein. In another experiment, cells were treated with lutein and the PPAR-γ antagonist GW9662 or the PPAR-γ agonist troglitazone prior to cerulein stimulation to determine the involvement of PPAR-γ activation. The results indicated that lutein increased PPAR-γ and SOCS3 levels in unstimulated cells. Cerulein increased phospho-specific forms of JAK2 and STAT3, and mRNA and protein expression of IL-6, but decreased SOCS3 levels in AR42J cells. Cerulein-induced alterations were suppressed by lutein or troglitazone. GW9662 alleviated the inhibitory effect of lutein on JAK2/STAT3 activation and IL-6 expression in cerulein-stimulated cells. In conclusion, lutein inhibited the activation of JAK2/STAT3 and reduced IL-6 levels via PPAR-γ-mediated SOCS3 expression in pancreatic acinar cells stimulated with cerulein.