Oxidized LDL Promotes Apoptosis and Expression of Pro-Inflammatory Mediators in Alternatively Activated Macrophages

Abstract

Accumulation of lipid within non-adipose tissues can induce inflammation by promoting macrophage infiltration and activation. Oxidized lipoproteins (oxLDL) have been known to induce cellular dysfunction in resident macrophages through pro-inflammatory and pro-apoptotic properties. However research into the pro-inflammatory and pro-apoptotic effects of oxLDL in alternatively activated (M2) macrophages has been relatively sparse. In this study, the proinflammatory and pro-apoptotic effects of oxLDL (at concentrations of 1 and 40μg/ml) were investigated in M2 macrophages. Incubation of M2 macrophage for 24 hours with 1 or 40μg/ml oxLDL induced pro-inflammatory molecules (MCP-1 and IL-6) production. Induction of cell death via apoptosis was observed after 24 hours incubation with 1 or 40μg/ml, but statistical significant induction was only observed with 40μg/ml oxLDL. Taking into consideration that M2 macrophages have been proposed as an appropriate target for type 2 diabetes, these findings may be of use in enhancing our knowledge of the adverse effects of oxLDL, particularly in the context of obesity, type 2 diabetes and the metabolic syndrome.