SLP65/SLP76 Csk-interacting membrane protein promotes hepatic ischemia-reperfusion injury by activating TLR4/Erk1/2-mediated macrophages M1 polarization.

BACKGROUND

SLP65/SLP76, Csk-interacting membrane protein (SCIMP), is a membrane protein plays a crucial role in the regulation of macrophage polarization. This study aimed to investigate the mechanism of SCIMP-mediated M1 polarization in liver macrophages and ischemia-reperfusion injury (IRI) in liver transplantation.

METHODS

Mice underwent orthotopic liver transplantation. In in vivo experiments, mice were divided into the Sham group, LT group, LT+Scramble group, LT+SCIMP (-) group, and LT+ERK1/2 (-) group, and SCIMP or ERK1/2 knockdown was performed using AAV-Erk1/2-RNAi-F4/80-EGFP and AAV-SCIMP-RNAi-F4/80-EGFP. In the subsequent in vitro experiments with primary cells, macrophages were divided into the Ctrl group, H/R group, H/R+Scramble group, H/R+SCIMP (-) group, and H/R+ERK1/2 (-) group, with SCIMP knockdown achieved using siRNA. Immunoprecipitation (IP) was used to detect the interaction between TLR4 and Erk1/2. Liver damage was detected by Hematoxylin and eosin (HE) staining. Polarization was detected by western blot (WB), RT-PCR, immunohistochemistry (IHC), immunofluorescence technique (IF), enzyme-linked immunosorbent assay (ELISA) and flow cytometry (FC).

RESULTS

Knockdown of SCIMP ameliorated hepatic IRI and liver macrophages M1 polarization. Mechanically, SCIMP promoted the interaction between Erk1/2 and TLR4 in hypoxia/reoxygenation (H/R)-induced liver macrophages, while the inhibition of Erk1/2 reduced liver macrophages M1 polarization and liver IRI.

CONCLUSION

SCIMP promotes hepatic ischemia-reperfusion injury by activating TLR4/Erk1/2-mediated liver macrophages M1 polarization, which might become a potential therapeutic target in clinic.