Alterations in Th17 Cells and Non-Classical Monocytes as a Signature of Subclinical Coronary Artery Atherosclerosis during ART-Treated HIV-1 Infection

Abstract

Cardiovascular disease (CVD) remains an important comorbidity in people living with HIV-1 (PLWH) receiving antiretroviral therapy (ART). Our previous studies performed in the Canadian HIV/Aging Cohort Study (CHACS) (>40 years-old; Framingham Risk Score (FRS) > 5%) revealed a 2-3-fold increase in non-calcified coronary artery atherosclerosis (CAA) plaque burden, measured by computed tomography angiography scan (CTAScan) as the total (TPV) and low attenuated plaque volume (LAPV), in ART-treated PLWH (HIV+) versus uninfected controls (HIV-). In an effort to identify novel correlates of subclinical CAA, markers of intestinal damage (sCD14, LBP, FABP2); cell trafficking/inflammation (CCL20, CX3CL1, MIF, CCL25); subsets of Th17-polarized and regulatory (Tregs) CD4⁺ T-cells, classical/intermediate/non-classical monocytes, and myeloid/plasmacytoid dendritic cells were studied in relationship with HIV and TPV/LAPV status. The TPV detection/values coincided with higher plasma sCD14, FABP2, CCL20, MIF, CX3CL1, and triglyceride levels; lower Th17/Treg ratios; and classical monocyte expansion. Among HIV⁺, TPV⁺ versus TPV^- exhibited lower Th17 frequencies, reduced Th17/Treg ratios, higher frequencies of non-classical CCR9^lowHLADR^high monocytes, and increased plasma fibrinogen levels. Finally, Th17/Treg ratios and non-classical CCR9^lowHLADR^high monocyte frequencies remained associated with TPV/LAPV after adjusting for FRS and HIV/ART duration in a logistic regression model. These findings point to Th17 paucity and non-classical monocyte abundance as novel immunological correlates of subclinical CAA that may fuel the CVD risk in ART-treated PLWH.

Keywords: HIV-1; Th17/Treg cells; antiretroviral therapy (ART); cardiovascular disease (CVD); myeloid/plasmacytoid dendritic cells; non-classical monocytes.

Figure 1

Decreased Th17 frequencies and Th17/Treg ratios coincide with subclinical CAA in ART-treated PLWH. The frequencies of regulatory CD4⁺ T-cells (Tregs; CD25⁺FOXP3⁺CD127⁻CD4⁺) (A), as well as Th17-polarized CD4⁺ T-cells (CCR6⁺CD26⁺CD161⁺) with memory (CD45RA⁻), effector memory (EM) (CD45RA⁻CCR7⁻), and central memory (CM) (CD45RA⁻CCR7⁺) phenotypes (B), were compared between TPV⁺ (n = 39) and TPV⁻ (n = 22) HIV⁺ participants. (C) Shown are the Th17/Treg ratios within the memory, EM, and CM Th17 subsets among TPV⁺ versus TPV⁻ HIV⁺ participants. Median and IQ range are indicated in red as horizontal lines. Differences among study groups were determined by Mann–Whitney rank test. p-values and statistical significance are indicated in the figures (*, p < 0.05; **, p < 0.01).

Figure 2

Non-classical CCR9^lowHLA-DR^high and M-DC8⁺HLA-DR^high monocytes are expanded in ART-treated PLWH with subclinical CAA. Total monocytes (Mo) were identified as cells lacking the T-cell lineage markers CD3 and CD4 and the DC marker CD1c, and expressing HLA-DR (Supplemental Figure S7). Shown is the expression of CCR2, CX3CR1, CCR9, HLA-DR, and M-DC8 on classical (CD14⁺⁺CD16⁻) (A), intermediate (CD14⁺⁺CD16⁺) (B), and non-classical (CD14⁺CD16⁺⁺) Mo (C), as well as the expression of CCR2, CX3CR1, and HLA-DR on M-DC8+ Mo (D), in PBMCs of TPV⁺ (n = 39) versus TPV⁻ (n = 22) HIV⁺ participants. Median and IQ range are indicated in red as horizontal lines. Differences among study groups were determined by Mann–Whitney rank test. p-values and statistical significance are indicated in the figures (**, p < 0.01).