Abstract
Background: Cardiovascular disease (CVD) is more common in people living with HIV (PLWH) and may be related to abnormal immune activation. With aging, the expansion of mutated hematopoietic clones or clonal hematopoiesis (CH) has been associated with CVD events in the general population and is hypothesized to be driven by systemic inflammation. We investigated whether CH was more common in PLWH compared to those without HIV, whether the distribution of CH mutations differed by HIV status, and whether CH was associated with subclinical coronary atherosclerosis in PLWH.
Methods: Study participants were selected from men in the Baltimore -Washington DC center of the Multicenter AIDS Cohort Study (MACS) who had had coronary CT angiography (CTA) as part of the MACS Cardiovascular Study 2. The MACS is a prospective study of the natural history of HIV infection in men who have sex with men, and includes both PLWH and HIV-uninfected men. Since the prevalence of CH increases with age, the oldest participants were preferentially included in this study. To detect CH, DNA extracted from viably frozen peripheral blood mononuclear cells or cell pellets was subjected to targeted, error-corrected, ultra-deep next generation sequencing (NGS) which included 70 genes frequently mutated in hematologic malignancies. CTA results and inflammatory biomarker levels were already available from MACS data.
Results: The current analysis was a cross-sectional study involving 118 participants: 86 (72.9%) PLWH and 32 (27.1%) HIV-uninfected men (HIV-). The groups were well-balanced in terms of known major risk factors for CH such as age and smoking. The median age was 53 and 54 years for PLWH and HIV- men, respectively (p=0.147). Caucasians represented 37 (43.0%) of PLWH and 21 (65.6%) of HIV- men. Out of 86 PLWH, 72 (83.7%) were on antiretroviral therapy (ART) at the time of the assessment; 41 (47.7%) on a PI-containing regimen and 31 (36.0%) on an NNRTI-containing regimen. The HIV viral load was under 400 copies/mL in 77 (89.5%) of PLWH, and the median (IQR) CD4+ count was 585 (397, 745)/mL. The prevalence of coronary artery stenosis of 50% or more was 12 (14.3%) in PLWH and 5 (16.1%) in HIV- men (p = 0.774).
Since the minimum size of the biologically relevant CH is unknown, we applied variant allele frequency (VAF) cut-offs of > 0.5% and > 1%. For both cutoffs, CH was significantly more frequent in PLWH than in HIV- men (p=0.012 and p=0.036, respectively) (Figure 1A). Mutations in epigenetic modifiers (DNMT3A, TET2) were the most common mutations among both PLWH and HIV- men. Interestingly, DNMT3A mutations were more frequent in PLWH (Figure 1B). For both VAF cut-offs, PLWH had significantly more somatic mutations than HIV-uninfected men (p = 0.043 and 0.033, respectively) (Figure 1C).
Since inflammation-mediated complications of CH become more apparent in people with larger clones, we focused on CH with VAF > 1% in order to determine the clinical consequences of CH in PLWH. As CH is known to be a risk factor for accelerated CVD in the general population, we asked whether CH was also associated with subclinical atherosclerosis in PLWH. Coronary artery stenosis > 50% (moderate/severe) was significantly more frequent in PLWH with CH compared to PLWH without CH (p = 0.032) (Figure 1 D). This difference remained significant in multivariable logistic regression models that adjusted for the Framingham coronary heart disease 10-year risk (p=0.017) and for the Framingham hard coronary heart disease 10-year risk (p<0.01).
Additionally, we examined the association of serum concentrations of several inflammatory markers such as CRP, IL-1b, IL-6, as well as white blood cell count, with the presence of CH in PLWH, but we found no significant associations.
Conclusions: CH was more common in PLWH compared to HIV-uninfected men, and PLWH had more somatic mutations. Moreover, the presence of CH was significantly associated with the presence of coronary artery stenosis > 50% (moderate/severe) in PLWH, even after adjusting for known CVD risk factors. The results from our exploratory analysis may provide a potential explanation for increased CVD in PLWH. Larger studies are warranted to further delineate the etiology of increased CH in PLWH and its impact on accelerated CVD.
No relevant conflicts of interest to declare.
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