BackgroundSystemic inflammation is a characteristic of both HIV-1 infection and aging (“inflammaging”). Intestinal epithelial barrier damage (IEBD) and microbial translocation (MT) contribute to HIV-associated inflammation, but their impact on inflammaging remains unclear.MethodsPlasma biomarkers for IEBD (iFABP), MT (LPS, sCD14), T-cell activation (sCD27), and inflammation (hsCRP, IL-6) were measured in 88 HIV-1 uninfected (HIVneg) and 83 treated, HIV-1-infected (HIVpos) adults from 20–100 years old.ResultsAge positively correlated with iFABP (r = 0.284, p = 0.008), sCD14 (r = 0.646, p = <0.0001) and LPS (r = 0.421, p = 0.0002) levels in HIVneg but not HIVpos subjects. Age also correlated with sCD27, hsCRP, and IL-6 levels regardless of HIV status. Middle-aged HIVpos subjects had elevated plasma biomarker levels similar to or greater than those of elderly HIVneg subjects with the exception of sCD14. Clustering analysis described an inflammaging phenotype (IP) based on iFABP, sCD14, sCD27, and hsCRP levels in HIVneg subjects over 60 years of age. The IP in HIVneg subjects was used to develop a classification model that was applied to HIVpos subjects to determine whether HIVpos subjects under 60 years of age were IP+. HIVpos IP+ subjects were similar in age to IP- subjects but had a greater risk of cardiovascular disease (CVD) based on Framingham risk score (p =  0.01).ConclusionsWe describe a novel IP that incorporates biomarkers of IEBD, MT, immune activation as well as inflammation. Application of this novel IP in HIV-infected subjects identified a group at higher risk of CVD.

The viral infectivity factor gene (vif) of HIV-1 increases the infectivity of viral particles by inactivation of cellular anti-viral factors, and supports productive viral replication in primary human CD4 T cells and in certain non-permissive T cell lines. Here, we demonstrate that Vif also contributes to the arrest of HIV-1 infected cells in the G(2) phase of the cell cycle. Viruses deleted in Vif or Vpr induce less cell cycle arrest than wild-type virus, while cells infected with HIV-1 deleted in both Vif and Vpr have a cell cycle profile equivalent to that of uninfected cells. Furthermore, expression of Vif alone induces accumulation of cells in the G(2) phase of the cell cycle. These data demonstrate a novel role for Vif in cell cycle regulation and suggest that Vif and Vpr independently drive G(2) arrest in HIV-1 infected cells. Our results may have implications for the actions and interactions of key HIV-1 accessory proteins in AIDS pathogenesis.

Apoptosis of CD4+ and CD8+ T cells has been shown in peripheral blood mononuclear cells (PBMCs) from HIV-infected adults analyzed after overnight culture. Because cell death may be an artifact of in vitro culture, and because there is little information on apoptosis in pediatric HIV disease, we undertook a cross-sectional analysis of apoptosis in PBMCs analyzed immediately ex vivo in HIV-infected children and adults. PBMCs from 22 children, four adolescents, and nine adults and seronegative age-matched control subjects were stained for CD4 and CD8 surface markers. Apoptotic cells were detected in a newly characterized flow cytometric assay by diminished forward and increased side scatter. Children with the most advanced disease had 9.9% (SEM 1.8) apoptotic CD4+ T cells above control, significantly higher than in asymptomatic patients [0.4% (SEM 2.3)], those with mild disease [2.2% (SEM 1.83)], and those with moderate disease [2.5 (SEM 3.6)] (p = 0.015). The percentages of both CD4+ and CD8+ T cell apoptosis were directly related to CD4+ T cell depletion (R2 = 0.23; p = 0.006; n = 32 and R2 = 0.2; p = 0.012; n = 30, respectively). Patients who responded to antiretroviral therapy with the greatest increase in CD4+ T cell percentage had the least CD4+ T cell apoptosis (R2 = 0.15; p = 0.1; n = 19). These findings show that the rate or extent of T cell death by apoptosis percentage of T cell apoptosis is significantly increased in HIV-infected children. The observed correlation of both CD4+ and CD8+ T cell apoptosis with CD4+ T cell depletion suggests that apoptosis plays a role in HIV pathogenesis and may be a useful marker of disease activity.

A panel of retinoid compounds (tretinoin, isotretinoin, acitretin, and R013-1470) were tested for inhibitory activity against Kaposi's sarcoma cell (KSC) cultures in vitro. Tretinoin was found to be the most effective retinoid tested, inhibiting the growth of KSC in vitro while having no effect on the expression of interleukin-6 and basic fibroblast growth factor, two important cytokines involved in KSC growth. Tretinoin also did not appear to downregulate the expression of receptors for these two cytokines. At low concentrations (10-9 M), acitretin and tretinoin selectively inhibited growth of early passage KSC. At higher concentrations (10'-10-' M), retinoid treatment induced a pattern of DNA degradation and morphological changes in KSC characteristic of apoptosis (programmed cell death). The inhibitory activity of tretinoin on KSC growth was decreased if human serum (but not fetal calf serum) was present in the growth medium, and partially restored by removal of serum lipids. These data suggest that retinoids possess potential as therapeutic agents in Kaposi's sarcoma. (J. Clin. Invest.

Cytomegalovirus (CMV) is associated with poor outcomes, including physical function impairment, in older HIV-uninfected adults. Whether CMV is associated with physical functional impairment in HIV-infected adults is unknown. The primary objective of this study was to determine the relationship between CMV-specific humoral and cell-mediated immune responses with functional impairment in well-controlled HIV infection. In a case-control study, low-function cases were matched by age, gender, and time from HIV diagnosis to highfunction controls. Quantitative CMV IgG and %CMV-specific CD8 + and CD4 + T cells (interferon-c expression following CMV pp65 stimulation) were used to estimate physical function. Among 30 low-function cases and 48 high-function matched controls, CMV IgG ranged from <10 to 8,830 EU/ml, including four controls with results <10 EU/ml. Each log 10 increase in CMV IgG was associated with 5-fold greater odds of low function ( p = 0.01); these findings were robust to adjustment for concomitant CD4 + count, tobacco use, and age; to exclusion of subjects with CMV IgG <10 EU/ml; and to adjustment for hepatitis C viremia. %CMV-specific CD4 + or CD8 + T cells were not associated with low function. In bivariable models, the relationship between CMV IgG and physical function was attenuated and was no longer significant when including IL-6, CD4/CD8 ratio, or the Veterans Aging Cohort Study Index score. High levels of CMV-specific IgG were associated with impaired physical function. Attenuation of the strength of this association in bivariable models suggests an indirect relationship mediated by systemic inflammation and immune suppression.

The importance of the Fas death pathway in human immunodeficiency virus (HIV) infection has been the subject of many studies. Missing from these studies is direct measurement of infected cell susceptibility to Fas-induced death. To address this question, we investigated whether T cells infected with HIV are more susceptible to Fas-induced death. We found that Fas cross-linking caused a decrease in the number of HIV-infected Jurkat T cells and CD4+peripheral blood leukocytes (PBLs). We confirmed this finding by demonstrating that there were more apoptotic infected than uninfected cells after Fas ligation. The increase in sensitivity of HIV-infected cells to Fas killing mapped to vpu, whilenef, vif, vpr, and second exon oftat did not appear to contribute. Furthermore, expression of Vpu in Jurkat T cells rendered them more susceptible to Fas-induced death. These results show that HIV-infected cells are more sensitive to Fas-induced death and that the Vpu protein of HIV contributes to this sensitivity. The increased sensitivity of HIV-infected cells to Fas-induced death might help explain why these cells have such a short in vivo half-life.

Background We investigated whether higher intensity exercise provided greater overall decrease in key markers of inflammation, and whether responses to exercise intensity differed by HIV serostatus. Methods People with HIV (PWH; n=32) and controls (n=37) aged 50-75 completed 12 weeks of moderate-intensity combined exercise then were randomized to moderate- or high-intensity exercise for 12 additional weeks (n=27 and 29, respectively). Inflammation biomarkers were measured at 0, 12, 24 weeks. Mixed and multiple regression models were adjusted for baseline inflammation, age and BMI. Results Baseline TNF-α, sTNFR2, and sCD14 were significantly higher among PWH than controls (p&lt;0.04). From week 0-12, changes in IL-6, TNF-α, sTNFR1 were not significantly different by HIV serostatus. We found no significant interaction between HIV serostatus/exercise intensity on week 12-24 changes in IL-6, TNF-α, sTNFR1. Among high-intensity exercisers, both PWH and controls had significant increases in sCD14 (p≤0.003), controls had significant increases in IL-10 (p=0.01), PWH had a non-significant decrease in hsCRP (p=0.07). Other markers were not significantly different by serostatus and exercise intensity. Discussion Moderate and high-intensity exercise elicited similar effects on inflammation among PWH and controls, with additional beneficial effects seen only among the high-intensity exercisers. Increase in sCD14 and attenuated IL-10 increase (PWH only) merit further study.

In these chronically infected viremic subjects, circulating IFNgamma-secreting CD4 T-cell responses were directed against epitope sequences found in the predominant strain of endogenous circulating plasma HIV-1, suggesting that escape from CD4 T-cell responses is not a common process in vivo.