MicroRNA-155 Deficiency in Kupffer Cells Ameliorates Liver Ischemia-Reperfusion Injury in Mice.

Background: MicroRNA-155 (miR-155) is known to be involved in autoimmune diseases, inflammation, and transplantation. However, its role in a warm hepatic ischemia-reperfusion (IR) model has not been fully elucidated. Methods: Partial hepatic IR was performed in wild-type and miR-155-deficient mice treated with or without GdCl3, and then the serum transaminase concentration and histology were analyzed. Kupffer cells (KCs) were isolated from the liver after IR, and immunohistochemistry was used to evaluate activation and polarization. In addition, the mRNA concentrations of various inflammatory cytokines were measured. Macrophages were obtained from the abdominal cavity and challenged with or without lipopolysaccharide to determine the influence of miR-155 deficiency on macrophage polarization in vitro. Furthermore, we used in vitro coculture assays to determine the effect of miR-155 deficiency on hepatocyte apoptosis induced directly by KCs. Results: miR-155 deficiency ameliorated liver ischemia-reperfusion injury, and inhibition of KCs by GdCl3 abolished this protective effect. miR-155 deficiency decreased CD80, CD86, and MHC-II expression in KCs following IR and tipped the M1/M2 balance toward an anti-inflammatory profile, where proinflammatory cytokine secretion was suppressed and interleukin-10 (IL-10) was enhanced. In addition, hepatocyte apoptosis was reduced in coculture with miR-155-deficient KCs in vitro. Conclusion: miR-155 deficiency plays an effective role in attenuating liver IRI likely by regulating the activation and inflammatory response, as well as modifying the polarization of KCs. Copyright (C) 2017 Wolters Kluwer Health, Inc. All rights reserved.

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