Abstract 637: Hyperhomocysteinemia-mediated sCD40L induction and CD16+CD40+ Monocyte Differentiation in Chronic Kidney Disease
Chronic kidney disease (CKD) with uremia is associated with high mortality of cardiovascular disease (CVD) and Hyperhomocysteinemia (HHcy) is highly prevalent in uremic CKD patients. Elevated inflammatory monocyte (MC) is a cellular hallmark of chronic inflammation and CVD. Here we investigated mechanism in uremia-associated HHcy on MC differentiation in CKD-associated CVD. Data base mining revealed that CD40 is induced in MC from CKD subjects and associated with CVD, inflammatory disease and MC activation. Blood samples were obtained from 28 vascular disease patients with or without CKD.
By flow cytometric analysis using CD14+ as a MC marker, we observed inflammatory CD16+ MC is increased in CVD, whereas CD40+ MC and CD16+CD40+ MC are increased in CKD-associated CVD. CD40+ MC expresses T cell activation markers CD86, HLA-DR, adhesion receptor CD62L, and chemokine receptor Ccr2. Plasma CD40L levels are increased in CVD, positively correlated with CD16+ MC. Interestingly, plasma Hcy levels are increased in CKD-associated CVD, positively correlated with cellular Hcy, plasma creatinine, CD16+CD40+ MC, and negatively correlated with S-adenosylmethionine/S-adenosylhomocysteine (SAM/SAH), an indicator of methylation. In addition, MC and T cell inflammatory cytokines TNFα, IL-6, and IFN[[Unable to Display Character: ɤ]] are induced in CKD-associated CVD subjects.
Next, we examined mechanism of CD16+CD40+ MC differentiation using cultured human peripheral blood mononuclear cells (hPBMC). CKD serum, Hcy, and CD40L induced CD16+CD40+ MC differentiation, which were prevented by folic acid and CD40L antibody. IFN[[Unable to Display Character: ϫ]], TNFα, and IL-6 synergistically induced CD16+CD40+ MC differentiation, which was blocked by neutralizing antibodies to TNFα and IL-6.
Hcy inhibited DNA methyltransferase 1 activity in isolated human blood MC. Finally, by gene analysis and pyrosequencing, we identified that the core promoter of CD40 gene is located at sole CpG island and hypomethylated at p65 consensus element in WBC from CKD-associated CVD subjects with low SAM/SAH ratio.
In conclusion, we identified CD16+CD40+ MC as a novel inflammatory MC subset which is increased in uremic HHcy-associated CVD. CD16+CD40+ MC differentiation may be due to CD40 promoter DNA hypomethylation.
Author Disclosures: J. Yang: None. E.T. Choi: None. S.P. Kunapuli: None. X. Yang: None. H. Wang: None.
- © 2015 by American Heart Association, Inc.