Fractalkine Aggravates LPS-induced Macrophage Activation and Acute Kidney Injury via Wnt/β-catenin Signaling Pathway

Abstract

Background: Fractalkine（CX3CL1, FKN），a CX3C gene sequence inflammatory chemokine, has been found to have pro-inflammatory and pro-adhesion effects. Macrophages are immune cells with a critical role in regulate inflammatory response. The imbalance of M1/M2 macrophage polarization can lead to aggravated inflammation. This study takes an attempt to investigate the mechanisms through which FKN regulates the macrophage activation and the acute kidney injury (AKI) involved in the inflammatory response induced by lipopolysaccharide (LPS) by using FKN-knockout (FKN-KO) mice and cultured macrophages.Results: In this study, we found that FKN and Wnt/β-catenin signaling have a positive interaction in macrophages. FKN-overexpression inhibited LPS-induced macrophage apoptosis. However, it enhanced the cell viability and transformed them into M2 type. The effects of FKN-overexpression were accelerated by activation of Wnt/β-catenin signaling. In the in vivo experiments, FKN deficiency suppressed the macrophage activation and reduced AKI induced by LPS. Inhibition of Wnt/β-catenin signaling and FKN deficiency further mitigated the pathologic process of AKI. Conclusions: We provide a novel mechanism underlying activation of macrophage in LPS-induced AKI. The positive interaction between FKN and Wnt/β-catenin signaling pathway may be the therapeutic target in kidney injury.