Interleukin-6 participates in human pancreatic stellate cell activation and collagen I production via TGF-ß1/Smad pathway.

Pancreatic stellate cells (PSCs) play a key role in fibrogenesis during alcoholic chronic pancreatitis (ACP). Transforming growth factor-ß1 (TGF-ß1) is a major regulator of PSC activation and extracellular matrix production. Interleukin-6 (IL-6) has shown to participate in TGF-ß1 production and rat PSC activation. This study aimed to investigate whether IL-6 promotes human PSC activation and collagen 1(Col1) production through the TGF-ß1/Smad pathway. Our results showed that the expression of IL-6 and IL-6R in activated PSCs and macrophages (Mφs) were enhanced in the pancreas of ACP compared to healthy controls and that the mRNA expression of IL-6, IL-6R, TGF-ß1, α-SMA or Col1a1 were significantly increased in the pancreas of ACP, showing positive correlations between elevated IL-6 levels and either TGF-ß1 or α-SMA or Col1a1 levels and between elevated TGF-ß1 levels and α-SMA or Col1a1 levels. In in vitro studies, we identified that IL-6R expression or IL-6 and TGF-ß1 secretions were significantly increased in, respectively, Mφs and PSCs by ethanol (EtOH) or lipopolysaccharide (LPS) stimulation while EtOH- or LPS-induced α-SMA or Col1a1 mRNA and protein production in PSCs were partially blocked by IL-6 antibody. IL-6-induced TGF-ß1 production in PSCs was antagonized by si-IL-6R RNA or by an inhibitor of STAT3. Additionally, IL-6-promoted α-SMA or Col1a1 protein production was blocked by TGF-ß1 antibody and IL-6-induced phosphorylation of Smad2/3 and transcription of α-SMA and Col1a1 mRNA were antagonized by si-TGF-ß1 RNA. Our findings indicate that IL-6 contributes to PSC activation and Col1 production through up-regulation of TGF-ß1/Smad2/3 pathway.