Effects of autophagy on macrophage adhesion and migration in diabetic nephropathy

Abstract

Objective: Macrophage infiltration in kidney is a major pathological feature of diabetic nephropathy (DN), which has been demonstrated associate with macrophages autophagy homeostasis. However, the relationships between autophagy and the infiltration response related of macrophages adhesion and migration are unknown. This study aims to investigate the impact of macrophages adhesion and migration by modulating autophagy.Methods: In vivo, rats were randomly distributed into control (NC) and DN groups. The pathological changes in renal tissue were assessed, and expression of CD68, LC3, P62 were analyzed. In vitro, RAW264.7 cells were divided into NC and high glucose (HG) groups. The capacity of macrophages adhesion migration and the expression of autophagy markers were observed with and without autophagy modulators (rapamycin, 3-methyladenine, chloroquine, and bafilomycin A1 for RAPA, 3-MA, CQ, BAFA). The macrophages autophagosome and the process of degradation and fusion of autophagosome-lysosome were observed by electron microscopy.Results: In vivo, renal injury is aggravated in diabetic rat compared with NC group. The autophagy level is inhibited in renal tissues of DN group with the increasing expression of CD68 and P62, while expression level of LC3 decreased (p < .05). In vitro, HG and 3-MA reduce the numbers of autophagosome of macrophages to inhibit autophagy level with decrease expression of LC3 and Beclin-1, but increase expression of P62, which promote the adhesion and migration capacity of macrophages (p < .05). Moreover, CQ and BAFA suppress autophagy level by inhibiting the process of autophagosome-lysosome degradation and fusion of macrophages, as well as the expression of LC3 and Beclin-1. We notice an increase expression of P62 by CQ and BAFA stimulation (p < .05). CQ and BAFA further facilitate the adhesion and migration capacity of macrophages. However, RAPA increases the numbers of macrophages autophagosome that inhibited by HG, resulting in a recovery of autophagy level with increase expression of LC3 and Beclin-1, whereas a reduction expression of P62, which lead to inhibition of adhesion and migration of macrophages induced by HG (p < .05)Conclusions: High glucose efficiently reduced the level of macrophage autophagy, following macrophages adhesion and migration enhanced when autophagy is suppressed. Activation of autophagosome improve the level of autophagy, but leading to a reduction of the macrophages adhesion and migration. While, inhibiting the process of degradation and fusion of autophagosome-lysosome suppress the level of autophagy and promote the macrophages adhesion and migration. These results indicate that high glucose may play an important role in macrophages adhesion and migration through modulating autophagy activities in diabetic nephropathy.