Lipoxin A inhibited the activation of hepatic stellate cells -T6 cells by modulating profibrotic cytokines and NF-κB signaling pathway.

Background: The deposition of extracellular matrix (ECM) during hepatic fibrosis is an intermediate process in the progression of multiple chronic liver diseases to cirrhosis. Because activated hepatic stellate cells (HSCs) are the main source of ECM, HSCs activation is the central link in the formation of liver fibrosis. It was reported that the analogs of lipoxin A (LXA) had anti-fibrotic effects, but the mechanisms are still not clear. This study was conducted to explore the possible mechanisms involved in the process of LXA-mediated inhibition of HSCs activation.

Methods: Rat HSC-T6 cells were activated by LPS and treated with LXA and/or BOC-2. The levels of ECM were assessed by hydroxyproline (Hyp) kit. The protein levels of α-SMA, Collagen I and III, MMP-2, MMP-9, TGF-β1, PDGF A and B, NF-κB P65, phosphorylated NF-κB P65 (P-P65) and NF-κB inhibitor α (I-κBα) were measured via western blot. The mRNA levels of MMP-2 and MMP-9 were observed by real-time PCR. The contents of TGF-β1 and PDGF were assessed by ELISA kits. Nuclear transfer assay kit was used to assess the activation and translation of NF-κB P65.

Results: (1) LPS activated HSC-T6 cells and up-regulated α-SMA, but LXA decreased LPS-induced α-SMA in HSC-T6 cells. (2) LXA inhibited LPS-induced Hyp production, meanwhile down-regulated LPS-induced Collagen I, Collagen III, MMP-2, and MMP-9 in HSC-T6 cells. (3) LXA decreased LPS-induced TGF-β1 and PDGF in HSC-T6 cells. (4) LXA repressed LPS-activated NF-κB signaling pathway, causing a reduction of I-κBα degradation, NF-κB phosphorylation, and NF-κB p65 transposition in HSC-T6 cells. (4) BOC-2, the blocker of LXA receptor, inhibited all the effects of LXA.

Conclusion: LXA inhibited HSCs activation through down-regulation TGF-β1/PDGF, and repression NF-κB signal pathway.