Grape seed proanthocyanidin inhibits inflammatory responses in hepatic stellate cells by modulating the MAPK, Akt and NF-κB signaling pathways

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Abstract
In the present study, we aimed to investigate the molecular mechanisms and prophylactic effects of grape seed proanthocyanidin (GSP) on lipopolysaccharide (LPS)-stimulated human hepatic stellate cells (HSCs). Cell counting and MTT assays were used to assess cell viability in the absence or presence of GSP. Reverse transcription-quantitative PCR (RT-qPCR) was performed for several inflammation-related genes (NOD1, NOD2, TLR2, TLR4, IL-1 β, IL-6, IL-8, iNOS and COX-2). The expression of anti-inflammatory cell signaling molecules, including c-Jun N-terminal kinase (JNK), p38, extracellular signal regulated kinase (ERK), Akt, nuclear factor-κB (NF-κB), inhibitory-κBα (IκBα), iNOS and COX-2, was evaluated by western blot analysis. Finally, IL-8 levels in the culture supernatant of HSCs were measured by ELISA. Pretreatment with GSP before LPS treatment significantly suppressed the mRNA expression of pro-inflammatory cytokines such as IL-1β, IL-6 and IL-8. GSP inhibited mRNA expression of LPS-induced TLR4, NOD2 and COX-2, in addition to inhibiting the expression of iNOS. GSP also inhibited LPS-induced NF-κB activation and IκBα phosphorylation. Concomitantly, GSP dose-dependently suppressed the activation of MAP kinases (JNK, ERK and p38) and Akt in LPS-stimulated HSCs. These data suggest that GSP inhibits inflammatory responses in HSCs by inactivating the NF-κB signaling pathway via MAP kinases. Thus, GSP may be considered as a novel drug for the treatment of hepatic inflammation, infectious diseases and fibrosis.

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