Recently we found that multi-walled carbon nanotube(MWCNT)exposure alters the mRNA levels of endoplasmic reticulum(ER)stress/autophagic genes,but the impact of biological molecules on this response is unclear.Herein,we compared the different actions of carboxylated MWCNTs(c-MWCNTs)pre-incubated with bovine serum albumin(BSA)or BSA-complexed free fatty acid(denoted as FFA)on macrophages derived from THP-1 monocytes(denoted as THP-1 macrophages).C-MWCNTs exhibited increased diameter and hydrodynamic size as well as decreased absolute zeta potential value after preincubation with BSA or FFA,which suggested a coating effect.Cytotoxicity or oxidative stress were not significantly induced after exposure to BSA-or FFA-coated c-MWCNTs.BSA-pre-incubated c-MWCNTs significantly enhanced the expression of the ER stress gene,DDIT3 and the autophagic genes,ATG5,BECN1,and PLIN2,but the mRNA levels of these genes was significantly decreased by FFA-pre-incubated c-MWCNTs.FFA-pre-incubated c-MWCNTs induced significantly higher lipid accumulation and interleukin-6(IL-6)protein level compared with BSA-p re-incubated c-MWCNTs,which suggested that FFA-p re-incubated c-MWCNTs may more effectively induce the formation of macrophage foam cells.Collectively,our data indicated that pre-incubation with FFA may influence c-MWCNT-induced ER stress/autophagic gene expression and foam cell formation in THP-1 macrophages.
