Evidence for the link between defective autophagy and inflammation in peripheral blood mononuclear cells of type 2 diabetic patients

Autophagy was shown to modulate inflammation in immune cells. This study was designed to evaluate the association between autophagy and inflammation in peripheral blood mononuclear cells (PBMCs) of type 2 diabetic (T2D) and non-diabetic (ND) subjects. The autophagy markers were measured by real-time PCR and western blot. The gene expression of pro- and anti-inflammatory cytokines was assessed by real-time PCR. Reduced transcription of BECN1 and LAMP2 and unchanged expression of MAP1LC3B and ATG5 were observed in PBMCs of T2D patients. Decreased LC3B-II and increased p62/SQSTM1 levels were found in PBMCs of diabetic patients. The p-mTOR level was higher in PBMCs of diabetic patients. An increase in both IL-1β and TNF-α gene expression, along with a decrease in the expression of IL-10, was observed in PBMCs of T2D patients. TNF-α mRNA expression was inversely correlated with the mRNA expression of BECN1 and LAMP2. TNF-α and IL-1β expression were negatively correlated with the protein levels of LC3B-II. TNF-α and IL-1β expression had also a positive correlation with protein level of p62. IL-10 mRNA expression was positively correlated with the mRNA expression of BECN1 and LAMP2 and protein levels of LC3B-II and negatively correlated with protein level of p62. In addition, p-mTOR level was positively correlated with IL-1β and TNF-α mRNA expression. The results revealed a reduced autophagy in PBMCs of T2D patients that is liked with an enhanced inflammation. The suppression of autophagy in PBMCs of diabetic patients may be associated with the activation of the mTOR signaling.