Loss of CXCR4 on non-classical monocytes in participants of the Women's Interagency HIV Study (WIHS) with subclinical atherosclerosis.

Abstract

To test whether human immunodeficiency virus (HIV) infection and subclinical cardiovascular disease (sCVD) are associated with expression of CXCR4 and other surface markers on classical, intermediate, and non-classical monocytes in women. sCVD was defined as presence of atherosclerotic lesions in the carotid artery in 92 participants of the Women's Interagency HIV Study (WIHS). Participants were stratified into four sets (n = 23 each) by HIV and sCVD status (HIV-/sCVD-, HIV-/sCVD+, HIV+/sCVD-, and HIV+/sCVD+) matched by age, race/ethnicity, and smoking status. Three subsets of monocytes were determined from archived peripheral blood mononuclear cells. Flow cytometry was used to count and phenotype surface markers. We tested for differences by HIV and sCVD status accounting for multiple comparisons. We found no differences in monocyte subset size among the four groups. Expression of seven surface markers differed significantly across the three monocyte subsets. CXCR4 expression [median fluorescence intensity (MFI)] in non-classical monocytes was highest among HIV-/CVD- [628, interquartile range (IQR) (295-1389)], followed by HIV+/CVD- [486, IQR (248-699)], HIV-/CVD+ (398, IQR (89-901)), and lowest in HIV+/CVD+ women [226, IQR (73-519)), P = 0.006 in ANOVA. After accounting for multiple comparison (Tukey) the difference between HIV-/CVD- vs. HIV+/CVD+ remained significant with P = 0.005 (HIV-/CVD- vs. HIV+/CVD- P = 0.04, HIV-/CVD- vs. HIV-/CVD+ P = 0.06, HIV+/CVD+ vs. HIV+/CVD- P = 0.88, HIV+/CVD+ vs. HIV-/CVD+ P = 0.81, HIV+/CVD- vs. HIV-/CVD+, P = 0.99). All pairwise comparisons with HIV-/CVD- were individually significant (P = 0.050 vs. HIV-/CVD+, P = 0.028 vs. HIV+/CVD-, P = 0.009 vs. HIV+/CVD+). CXCR4 expression on non-classical monocytes was significantly higher in CVD- (501.5, IQR (249.5-887.3)) vs. CVD+ (297, IQR (81.75-626.8) individuals (P = 0.028, n = 46 per group). CXCR4 expression on non-classical monocytes significantly correlated with cardiovascular and HIV-related risk factors including systolic blood pressure, platelet and T cell counts along with duration of antiretroviral therapy (P < 0.05). In regression analyses, adjusted for education level, study site, and injection drug use, presence of HIV infection and sCVD remained significantly associated with lower CXCR4 expression on non-classical monocytes (P = 0.003), but did not differ in classical or intermediate monocytes. CXCR4 expression in non-classical monocytes was significantly lower among women with both HIV infection and sCVD, suggesting a potential atheroprotective role of CXCR4 in non-classical monocytes.