Statin-regulated phagocytosis and efferocytosis in physiological and pathological conditions

Efferocytosis (clearance of apoptotic cells by phagocytosis without inducing inflammation and autoimmunity) is an important mechanism in the resolution of inflammatory processes. Efficient efferocytosis inhibits the accumulation of apoptotic cells/debris and maintains homeostasis before the onset of necrosis (secondary necrosis), which promotes inflammation or injury. Moreover, the detection and clearance of apoptotic cells can promote anti-inflammatory responses. Defective efferocytosis is involved in the pathogenesis of several diseases, such as atherosclerosis, chronic inflammation, autoimmunity and cancer. Statins are 3-hydroxy-3-methylglutaryl coenzyme A-reductase inhibitors which exert cholesterol-lowering effects plus multiple pleiotropic properties, such as inhibition of inflammation and macrophage proliferation. Statins exhibit anti-inflammatory properties by reducing both the prenylation of signaling molecules with downregulation of gene expression and the expression of adhesion molecules, as well as the levels of cytokines and chemokines. Additionally, statins suppress the prenylation of GTPases, such as Rac-1, as a positive regulator of efferocytosis, and RhoA, as a negative regulator of efferocytosis. However, statins alter the membrane balance of Rho GTPases in efferocytosis toward Rac-1. Efferocytosis has modifiable targets, which can be exploited for the treatment of several diseases, although limited attention has been given to the mechanisms by which statins regulate efferocytosis and the resulting therapeutic implications. In this review, we will elaborate on the mechanisms underlying the modulation of apoptotic cell clearance by statins, which, in turn, inhibits uncontrolled inflammation and ensuing diseases.