The molecules associated with HIV that promote inflammation and may lead to immune dysfunction are considered below.
High-sensitivity CRP, one of the most common markers of inflammation, is a well-known risk factor for CVD and a predictor of all-cause mortality [
125]. Higher concentrations of hs-CRP in PLWH in comparison to the general population have been demonstrated. Increased levels of D-dimer, a marker of deterioration of CV condition and endothelial dysfunction, are also associated with increased HIV viral load, microbial translocation, immune activation, and mortality risk [
126].
Interleukin-6 belongs to the interleukin-6 family, a group of cytokines that includes IL-6, IL-11, IL-27, ciliary neurotrophic factor, leukemia inhibitory factor, oncostatin M, cardiotrophin 1, and cardiotrophin-like cytokine [
127]. IL-6 is a pro-inflammatory cytokine in which higher circulating levels are associated with HIV replication [
128]. Increased levels of IL-6 are related to the development of CVD and can predict mortality due to CVD or CV events [
71]. In HIV infection, IL-1β induces TNF-α and IL-6 expression, leading to sustained proinflammatory responses. HIV is also a factor in the production of IL‐1β via transforming pro-IL-1β into bioactive IL-1β, a cytokine that is associated both with the progression to AIDS and higher CVD risk [
129]. A detectable HIV viral load induces a higher TNF-α serum concentration that can initiate and accelerate apoptosis, atherogenesis, thrombosis, vascular remodeling, and oxidative stress and therefore increase cardiovascular risk [
130,
131]. TGF-β is related to atherosclerosis-associated vascular inflammation, and the overexpression of TGF-β in PLWH promotes viral replication and plays an important role in the progression of HIV infection and associated diseases [
132]. Chronic increase in osteopontin level, reported in PLWH, is another risk factor for CVD, since osteopontin plays a role in the secretion of multiple proinflammatory molecules, including IL-10, IL-12, IL-3, IFN-γ, and can also be used to predict major adverse cardiovascular events [
133]. Elevated levels of sCD14 observed in PLWH have been associated with microbial translocation, increased immune activation, and a greater risk of mortality and morbidity due to CVD [
134].
The expression of the adhesion molecules VCAM-1 and ICAM-1, which mediate inflammation and promote leukocyte migration, is stimulated by HIV-Tat-1 protein and pro-inflammatory cytokines such as TNF-α and IL-1β [
135]. Toll-like receptors activate the expression of VCAM-1 and ICAM-1 in the endothelium, a response that is strongly associated with increased intimal leukocyte accumulation, an important factor in the pathogenesis of human atherosclerosis [
136]. VCAM-1 is a diagnostic biomarker of endothelial dysfunction and vascular injury; together with ICAM-1, it has been used in many clinical studies to estimate the risk of CVD [
137]. It has been reported that the expression of adhesion molecules in PLWH is significantly higher than in the general population [
138].