T-cell phenotypes, apoptosis and inflammation in HIV+ patients on virologically effective cART with early atherosclerosis

Abstract

Objective: We investigated the potential relationship between T-cell phenotype, inflammation, endotoxemia, and atherosclerosis evaluated by carotid intima-media thickness (IMT) in a cohort of HIV-positive patients undergoing long-term virologically suppressive combination antiretroviral therapy (cART).

Design: We studied 163 patients receiving virologically suppressive cART.

Methods: We measured IMT (carotid ultrasound); CD4+/CD8+ T-cell activation (CD38, CD45R0), differentiation (CD127), apoptosis (CD95), and senescence (CD28, CD57) (flow cytometry); plasma sCD14, IL-6, TNF- α, sVCAM-1, hs-CRP, anti-CMV IgG (ELISA); LPS (LAL). The results were compared by Mann-Whitney, Kruskal-Wallis or Chi-square tests, and factors associated with IMT were evaluated by multivariable logistic regression.

Results: Of 163 patients, 112 demonstrated normal IMT (nIMT), whereas 51 (31.3%) had pathological IMT (pIMT: ≥1 mm). Of the patients with pIMT, 22 demonstrated an increased IMT (iIMT), and 29 were shown to have plaques. These patient groups had comparable nadir and current CD4+, VLs and total length of time on cART. Despite similar proportions of CD38-expressing CD8+ cells (p = .95), pIMT patients exhibited higher activated memory CD8+CD38+CD45R0+ cells (p = .038) and apoptotic CD4+CD95+ (p = .01) and CD8+CD95+ cells (p = .003). In comparison to nIMT patients, iIMT patients tended to have lower numbers of early differentiated CD28+CD57- memory CD4+ (p = .048) and CD28-CD57-CD8+ cells (p = .006), both of which are associated with a higher proliferative potential. Despite no differences in plasma LPS levels, pIMT patients showed significantly higher circulating levels of sCD14 than did nIMT patients (p = .046). No differences in anti-CMV IgG was shown. Although circulating levels of sCD14 seemed to be associated with a risk of ATS in an unadjusted analysis, this effect was lost after adjusting for classical cardiovascular predictors.

Conclusions: Despite the provision of full viral suppression by cART, a hyperactivated, pro-apoptotic T-cell profile characterizes HIV-infected patients with early vascular damage, for whom the potential contribution of subclinical endotoxemia and anti-CMV immunity should be investigated further.

Figure 1. Different peripheral T-cell immune phenotypes according to the degree of carotid intima-media thickness.

A–B. Activated CD8+ T-cells were defined by the expression of CD38, whereas memory activated CD8+ T-cells were defined by the co-expression of CD45R0 and CD38. A. nIMT and pIMT HIV+ patients exhibited similar number of CD8+CD38+ T-cells. B. pIMT patients had significantly higher memory activated CD8+CD38+CD45R0+ T-cells in comparison to nIMT patients (p = .038). C–D. Apoptotic T-cells were defined by the expression of CD95 on CD4+ and CD8+ cells. As compared to nIMT, pIMT patients exhibited a significantly higher number of CD4+CD95+ cells (p = .01) (C), and CD8+CD95+ T-cells (p = .003) (D). E. CD127 expression on CD4+ T-cells was similar between the nIMT and pIMT groups. F. A non-significant trend towards greater number of CD8+CD127+ cells was observed among pIMT patients as compared to nIMT patients (p = .08).

Figure 2. T-cell immunosenescence according to the degree of intima-media thickness.

A. A non-significant tendency towards reduced early differentiated memory (CD28+CD57−) CD4+ T-cell numbers was observed for pIMT patients in comparison to nIMT patients (p = .09). B. No differences were observed in early differentiated memory CD8+ CD28+CD57− T-cells between the two study groups. C–D. The number of late-differentiated memory (CD28–CD57+) CD4+ (C) and CD8+ (D) T-cells was comparable between nIMT and pIMT groups. E–F. We observed no difference in CD4+CD28+CD57+ (E) and CD8+CD28+CD57+ (F) T-cells between the nIMT and pIMT groups. G. No major difference in CD4+CD28–CD57− T-cells were observed between nIMT and pIMT patients. H. Compared to nIMT patients, pIMT patients tended to have lower number of CD8+CD28–CD57− cells (p = .06).

Figure 3. Markers of Inflammation, endothelial cell activation, microbial translocation and anti-CMV IgG according to the degree of intima-media thickness.

A. IL-6 plasma levels were increased in pIMT patients in comparison to nIMT patients, albeit not-reaching significance (p = .08). B–F. When nIMT patients were compared to pIMT patients, no differences in TNF-α (B), s-VCAM-1 (C) hs-C-reactive protein (hs-CRP) (D) plasma levels were detected. E. nIMT and pIMT patients exhibited similar plasma levels of lipopolysaccharide (LPS). F. pIMT patients showed significantly higher circulating levels of sCD14 in comparison to nIMT patients (p = .046). G. nIMT and pIMT patients displayed comparable levels of anti-CMV IgG.