Alejandro Vallejo

Altered metabolism of gut microbiota contributes to chronic immune activation in HIV-infected individuals.

Altered interplay between gut mucosa and microbiota during treated HIV infection may possibly contribute to increased bacterial translocation and chronic immune activation, both of which are predictors of morbidity and mortality. Although a dysbiotic gut microbiota has recently been reported in HIV+ individuals, the metagenome gene pool associated with HIV infection remains unknown. The aim of this study is to characterize the functional gene content of gut microbiota in HIV+ patients and to define the metabolic pathways of this bacterial community, which is potentially associated with immune dysfunction. We determined systemic markers of innate and adaptive immunity in a cohort of HIV-infected individuals on successful antiretroviral therapy without comorbidities and in healthy non-HIV-infected subjects. Metagenome sequencing revealed an altered functional profile, with enrichment of the genes involved in various pathogenic processes, lipopolysaccharide biosynthesis, bacterial translocation, and other inflammatory pathways. In contrast, we observed depletion of genes involved in amino acid metabolism and energy processes. Bayesian networks showed significant interactions between the bacterial community, their altered metabolic pathways, and systemic markers of immune dysfunction. This study reveals altered metabolic activity of microbiota and provides novel insight into the potential host–microbiota interactions driving the sustained inflammatory state in successfully treated HIV-infected patients.

The CD4/CD8 ratio in HIV-infected subjects is independently associated with T-cell activation despite long-term viral suppression

OBJECTIVES HIV-infected subjects on antiretroviral therapy often fail to normalize the CD4/CD8 ratio despite CD4 count normalization. We aimed to analyze the biological significance of this finding. METHODS Cross-sectional analysis in 20 HIV-infected subjects on stable triple-ART, plasma HIV RNA <40 copies/mL for at least 2 years and CD4 count >350 cells/mm(3). Laboratory measurements included T-cell activation (HLADR(+), CD38(+)) and senescence (CD57(+)), lipopolysaccharide (LPS), sCD14 and the HIV latent reservoir (number of latently infected memory CD4 cells carrying replication-competent virus). RESULTS CD4/CD8 ratio was positively correlated with CD4 nadir (r = 0.468, p = 0.038) and accumulated ART exposure (r = 0.554, p = 0.0011), and negatively with viral load before ART initiation (r = -0.547, p = 0.013), CD4(+)HLADR(+)CD38(+) T-cells (r = -0.428, p = 0.086) and CD8(+)CD57(+) T-cells (r = -0.431, p = 0.084). No associations with LPS, sCD14 or HIV latent reservoir were found. After the multivariate analyses, the CD4/CD8 ratio remained independently associated with CD4(+)HLADR(+)CD38(+) T-cells and CD8(+)HLADR(+) T-cells. CONCLUSIONS In our study in subjects on suppressive ART the CD4/CD8 ratio was independently associated with T-cell activation. Our results must be confirmed in larger studies, as this parameter might be a useful clinical tool to identify subjects with ongoing immune activation despite long-term viral suppression.

Intensification of Antiretroviral Therapy with a CCR5 Antagonist in Patients with Chronic HIV-1 Infection: Effect on T Cells Latently Infected

Objective The primary objective was to assess the effect of MVC intensification on latently infected CD4+ T cells in chronically HIV-1-infected patients receiving antiretroviral therapy. Methods We performed an open-label pilot phase II clinical trial involving chronically HIV-1-infected patients receiving stable antiretroviral therapy whose regimen was intensified with 48 weeks of maraviroc therapy. We analyzed the latent reservoir, the residual viremia and episomal 2LTR DNA to examine the relationship between these measures and the HIV-1 latent reservoir, immune activation, lymphocyte subsets (including effector and central memory T cells), and markers associated with bacterial translocation. Results Overall a non significant reduction in the size of the latent reservoir was found (p = 0.068). A mean reduction of 1.82 IUPM was observed in 4 patients with detectable latent reservoir at baseline after 48 weeks of intensification. No effect on plasma residual viremia was observed. Unexpectedly, all the patients had detectable 2LTR DNA circles at week 24, while none of them showed those circles at the end of the study. No changes were detected in CD4+ or CD8+ counts, although a significant decrease was found in the proportion of HLA-DR+/CD38+ CD4+ and CD8+ T-cells. LPS and sCD14 levels increased. Conclusions Intensification with MVC was associated with a trend to a decrease in the size of the latent HIV-1 reservoir in memory T cells. No impact on residual viremia was detected. Additional studies with larger samples are needed to confirm the results. Trial Registration ClinicalTrials.gov NCT00795444

The effect of intensification with raltegravir on the HIV-1 reservoir of latently infected memory CD4 T cells in suppressed patients.

Objectives:The stability of the reservoir of latently infected memory CD4+ T-cells may be associated with continuous replenishment from residual HIV-1, not completely eliminated by otherwise successful antiretroviral therapy (ART). Treatment intensification could help to control residual virus and to modify the latent reservoir. The objective of this work is to assess the effect of intensifying therapy with raltegravir on the HIV-1 cell reservoir. Design:A pilot open-label phase-II clinical trial was performed to analyze ART intensification with raltegravir after 48 weeks in chronically HIV-1-infected patients on stable ART. Methods:We measured the number of latently infected memory CD4+ T cells, residual viremia, 2-long terminal repeat circles, CD4+/CD8+ T-cell activation, lymphocyte subpopulations, gut homing receptor, and bacterial translocation. Results:A significant decay of HIV-1 latent reservoir was observed after intensification in the nine patients included (P = 0.021). No variation was found in either residual viremia or 2-long terminal repeat circles, whereas CD8+ T-cell activation decreased at week 36 (P = 0.028). No differences were found in naive T-cell or effector memory cell counts, and the frequencies of gut homing receptor on activated or effector memory CD8+ T cells. Bacterial translocation was stable, with the exception of a late decrease in lipopolysaccharide levels. Conclusions:In this pilot noncomparative trial, treatment intensification with raltegravir significantly decreased the latent cellular HIV-1 reservoir and CD8+ T-cell activation. Despite the limitations inherent to trial design, our results suggest that ART intensification should be considered as an adjuvant strategy to eradicate HIV-1 infection.

Influence of the Toll-Like Receptor 9 1635A/G Polymorphism on the CD4 Count, HIV Viral Load, and Clinical Progression

Objective:To analyze the influence of single-nucleotide polymorphisms (SNPs) in TLR2 (1892A/C and 2258G/A), TLR4 (896A/G and 1196C/T), and TLR9 (1635A/G) genes on CD4 count, HIV viral load, and clinical progression in a cohort of naive HIV-infected patients. Methods:TLR2, TLR4, and TLR9 SNPs were analyzed in 369 naive HIV-infected patients by real-time polymerase chain reaction and melting curve technology. TLR2 1892C/A and TLR9 1635A/G SNPs were also analyzed in a non-HIV-infected population. Multivariate multiple regression analysis and Cox regression analyses were performed to assess the potential association between the SNPs and the end points. Results:TLR2 and TLR4 SNPs were not associated with the end points of the study. Regarding TLR9 1635A/G SNP, patients with the AA genotype showed statistically lower CD4 count (P = 0.003) and higher HIV viral load (P = 0.0018) compared with AG+GG genotypes at cohort entry. The multivariate analysis showed a significant association between the 1635AA genotype and both end points. Cox regression analysis showed that HIV clinical progression to clinical stage C and death due to AIDS-related events under antiretroviral therapy was earlier in patients with the 1635AA genotype (P = 0.035, P = 0.017, respectively). Conclusions:TLR9 1635A/G SNP might have a role in HIV clinical disease progression.

Premature immunosenescence in HIV-infected patients on highly active antiretroviral therapy with low-level CD4 T cell repopulation

OBJECTIVES To analyse the role of thymic function and its association with cellular immunosenescence markers in patients with low-level CD4 T cell repopulation, despite complete HIV RNA replication control on highly active antiretroviral therapy (HAART). METHODS Cellular immunosenescence markers comparing patients with CD4 T cell counts <or=250 cells/mm(3) for >or=48 weeks (n = 11) and patients with a CD4 T cell count >or=500 cells/mm(3) (n = 11) were investigated. Both groups were also compared with 11 healthy volunteers of similar age. Naive CD4 T cell counts, beta- and delta-T cell rearrangement excision circles, recent thymic emigrants, replicative senescence marker, cell activation, and rate of apoptosis were analysed. The Mann-Whitney U-test was used to compare parameters between both low-level and high-level CD4 T cell repopulation groups, and healthy volunteers. RESULTS Our results showed a lower thymic activity in patients with low-level CD4 T cell repopulation, leading to a decline in CD4 T cell production. On the other hand, a higher activation along with a higher replicative senescence of CD4 T cells contributed to a higher rate of apoptotic CD4 T cells in this group of patients. CONCLUSIONS We propose a model with several different related mechanisms involved in premature immune senescence in HIV-infected patients with low-level CD4 repopulation on HAART. The understanding of such different mechanisms could help find effective strategies to prevent immune decay.

Thymic volume is associated independently with the magnitude of short- and long-term repopulation of CD4+ T cells in HIV-infected adults after highly active antiretroviral therapy (HAART)1

Age is one of the main factors involved in the rapidity and the magnitude of CD4+ T cell repopulation in human immunodeficiency virus (HIV)‐infected patients on highly active antiretroviral treatment (HAART). Improved thymic function has been suggested as the main factor associated with CD4+ T cell restoration after HAART. This work was undertaken to determine, among host factors, the predictor variable at baseline involved in the magnitude of short‐ and long‐term recovery of CD4+ T cells after HAART. HIV‐RNA levels and CD4+ T cell numbers were determined in 54 HIV‐infected adults at baseline and at weeks 4, 12, 48 and 96 after HAART. T cell subpopulations were determined by flow cytometry, thymic volume by computed tomography, T cell receptor excision circle (TREC)‐bearing cells by quantitative polymerase chian reaction (PCR) and interleukin (IL)‐7 levels by enzyme linked immunosorbent assay at baseline. The phenotype of patients’ isolates was determined by infecting GHOST cells expressing CCR5 and CXCR4. The possible interference of phenotype with thymic function was also analysed. Baseline thymic volume was associated independently with the magnitude of short‐ and long‐term recovery of CD4+ T cells after HAART, despite the patients’ viral phenotype. The measurement of thymic volume before therapy may predict the magnitude of T cell increase. This result could have important clinical implications not only in HIV‐infected patients, but also in other scenarios of T cell depletion such as bone marrow transplantation and chemotherapy.

Correlation between different methods to measure microbial translocation and its association with immune activation in long-term suppressed HIV-1-infected individuals.

Introduction:Microbial translocation (MT) has been proposed as one of the triggering mechanisms of persistent immune activation associated to HIV-1 infection. Our objectives were to determine the correlation between different measurements of MT in suppressed HIV-1–infected individuals and to evaluate its correlation with immune activation. Methods:Eighteen suppressed HIV-1–infected patients with CD4+ T-cell count above 350 cells per cubic millimeter and undetectable plasma viral load, included in antiretroviral treatment intensification clinical trials, were evaluated. Samples obtained at baseline and at established time points during the trials were analyzed. Lipopolysaccharide (LPS), lipopolysaccharide binding protein (LBP), soluble CD14 (sCD14), and bacterial 16S ribosomal DNA (16S rDNA), and markers of immune activation were determined. Results:We analyzed 126 plasma samples from the 18 patients. LPS significantly correlated with sCD14 (P < 0.001, r = 0.407) and LBP (P = 0.042, r = 0.260). Also, a significant correlation was found between sCD14 and LBP (P = 0.009, r = 0.325) but not between bacterial 16S rDNA and LPS, sCD14, or LBP (P = 0.346, P = 0.405, and P = 0.644). On the other hand, no significant correlation was found between LPS, sCD14, or LBP and CD4+ (P = 0.418, P = 0.619, and P = 0.728) or CD8+ T-cell activation (P = 0.352, P = 0.275, and P = 0.124). Bacterial 16S rDNA correlated with activated CD4+ T cells (P = 0.005, r = 0.104) but not with activated CD8+ T cells (P = 0.171). Conclusions:There is a good correlation in the quantification of LPS, sCD14, and LBP levels, but not with bacterial 16S rDNA, as measurements of MT. We are unable to ensure that MT directly triggers T-cell immune activation at least among these patients with relatively good immune recovery and under treatment intensification.

Infecciones por VIH-2 y HTLV-I/II en España

Hasta diciembre de 2002, se han identificado en Espana un total de 56, 566 y 109 casos de infeccion por los virus de la leucemia humana T tipos I y II (HTLV-I, HTLV-II) y de la inmunodeficiencia humana tipo 2 (VIH-2), respectivamente. La mayor parte de los sujetos infectados por VIH-2 y HTLV-I corresponden a inmigrantes procedentes de zonas endemicas, o espanoles que han viajado a aquellas regiones o que han mantenido relaciones sexuales con oriundos de ellas. Por el contrario, la infeccion por el HTLV-II predomina entre espanoles adictos a drogas por via parenteral (ADVP) que con frecuencia estan coinfectados por el VIH-1. Entre los sujetos infectados por el HTLV-I, 12 pacientes han desarrollado mielopatia subaguda y cuatro leucemia de celulas T del adulto. Tan solo 20 (18,3%) de los pacientes infectados por el VIH-2 han desarrollado sida. No se ha observado un incremento en la incidencia de la infeccion por el VIH-2 y el HTLV-I en estos anos. Por el contrario, la infeccion por el HTLV-II se ha extendido rapidamente en el colectivo de pacientes infectados por el VIH-1 adictos a drogas por via parenteral (ADVP) en prisiones con una prevalencia del 18% en determinadas carceles espanolas. No obstante, la prevalencia de dicha infeccion sigue siendo baja fuera del ambito carcelario entre los pacientes infectados por el VIH-1 ADVP (4,7%).

Thymic function-related markers within the thymus and peripheral blood: Are they comparable?

The thymus involutes with age and its functionality has traditionally been assumed to be limited early in life. However, some studies have demonstrated that thymic function persists in adults. In humans, since it is difficult to obtain thymic samples from healthy individuals, indirect parameters have been used to study the thymic function. The aim of this study was to compare thymic function parameters within both the thymus and peripheral blood mononuclear cells from thirty-three patients who underwent cardiac surgery, as well as to relate these parameters with aging. The proportion of peripheral naïve T cells and intrathymic T cell differentiation stages, as well as peripheral and intrathymic TREC levels were analysed. We demonstrated that thymopoyesis persists in the healthy elderly since all T cell differentiation stages were found within the thymus. Among the studied parameters, peripheral TREC levels are found to be a good thymic function marker since they correlated with age. In healthy individuals, peripheral TREC levels are a good reflect of thymic function as demonstrated by their correlation with intrathymic TREC values.