Role of PPAR-gamma in the modulation of CD36 and FcgammaRII induced by LDL with low and high degrees of oxidation during the differentiation of the monocytic THP-1 cell line

Scavenger or Fcγ receptors are important for capture and clearance of modified LDL particles by monocytes/macrophages. Uptake via scavenger receptors is not regulated by intracellular levels of cholesterol and in consequence, macrophages develop into foam cells in the arterial intima. The levels of scavenger receptor CD36 are increased in atherosclerotic lesions and there is evidence that some components of oxLDL auto-regulate the expression of this receptor. Fcγ receptor expression is increased in cardiovascular diseases but it is not known weather their expression is regulated by oxLDL. The biological properties of oxLDLs vary depending on the degree of oxidation. In the present study we investigated the effect of LDL particles showing extensive or low oxidation (HoxLDL and LoxLDL) on the expression of CD36 and FcγRII in a human monocytic cell line (THP-1), differentiated or not to macrophage, and the involvement of PPARγ. It was found that both forms of oxLDL are able to increase the expression of CD36 and FcγRII and that this effect is dependent on the degree of oxidation and of the stage of cell differentiation (monocyte or macrophage). We also showed that the increased expression of FcγRII is dependent on PPARγ whereas that of the CD36 is independent of PPARγ.