Natalia Soriano-Sarabia

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.

The TLR4 ASP299GLY polymorphism is a risk factor for active tuberculosis in Caucasian HIV-infected patients.

INTRODUCTION Tuberculosis (TB) is a pandemic infectious disease especially frequent in HIV-infected patients. Toll-like receptor (TLR) 4 has been described to play a main role in the innate immunity against TB. In fact, single nucleotide polymorphisms (SNPs) in TLRs may influence AIDS disease progression. The association between two particular SNPs in human TLR4 (Asp299Gly and Thr399Ile) and active TB has been studied in non-HIV Africans with contradictory results. However, studies focusing on the effect of these TLR4 SNPs in active TB within a Caucasian HIV population are lacking. OBJECTIVES To analyze the association between TLR4 Asp299Gly and Thr399Ile SNPs and active TB, in Caucasian Mediterranean HIV-infected individuals. METHODS 468 HIV-infected patients were analyzed. TLR4 genotyping was performed by real-time PCR and melting curve technology. RESULTS TB was diagnosed in 59 (12,6%) patients. In a bivariate analysis several variables resulted significantly associated with active TB; intravenous drugs use (OR= 2.2; 95% CI [1.2-3.8]), hepatitis C virus (HCV) co-infection (OR= 3.4; 95% CI [1.6-7.1]), CD4 count (p<0.001), HIV viral load (p=0.003), latent TB prophylaxis (OR= 0.3; 95% CI [0.1-0.5]), and TLR4 Asp299Gly (OR= 2.0; 95% CI [1.1-4.2]). No statistical association was found for the TLR4 Thr399Ile. After a multivariate analysis, HCV co-infection (OR= 3.8; 95% CI [2.2-6.5]), baseline CD4 count (OR= 0.996; 95% CI [0.994-0.998]), TLR4 Asp299Gly (OR= 2.57; 95% CI [1.18-5.61]) were independently associated with active TB and inversely with latent TB prophylaxis (OR= 0.24; 95% CI [0.01-0.60]). CONCLUSIONS We describe an independent association between TLR4 Asp299Gly SNP and active TB in Caucasian Mediterranean HIV-infected patients.

HCV RNA in peripheral blood cell subsets in HCV–HIV coinfected patients at the end of PegIFN/RBV treatment is associated with virologic relapse

Summary.  Extrahepatic replication may have important implications for the treatment of hepatitis C virus (HCV). Our aim was to analyse the association between the presence of positive/negative strand HCV RNA in different peripheral blood cell subsets at the end of PegIFN/RBV treatment, and treatment response in HIV‐coinfected patients. Thirty‐four HCV–HIV coinfected patients who concluded 48 weeks of PegIFN/RBV treatment were included in the present study. Positive/negative strand HCV RNA was detected by amplification of the 5′ untranslated region (5′ UTR) using high‐temperature RT‐PCR in immunomagnetic‐isolated cell subsets. Twenty‐three patients (67.6%) had sustained virologic response (SVR) while 11 patients (32.4%) relapsed. The frequency of positive/negative strand HCV RNA in any cell subsets was significantly lower in patients with SVR (8.6%) compared to relapsers (63.6%) (P = 0.002). Baseline HCV viral load was statistically higher among patients who relapsed (P = 0.008), while patients with SVR had very early virologic response more frequently (P = 0.003). Multivariate analysis showed, among these three variables, that only the presence of positive/negative strand HCV RNA was independently associated with relapse [P = 0.024; OR 14 (14–137)]. In conclusion, the presence of positive/negative strand HCV RNA at the end of treatment is associated with relapse among HCV–HIV coinfected patients and might have important implications in the clinical practice.

Thymic volume predicts CD4 T-cell decline in HIV-infected adults under prolonged treatment interruption.

Objective: To analyze the predictive capacity of thymic volume in CD4 T-cell loss after treatment interruption in HIV-infected patients with high nadir CD4 count. Methods: Thirty-nine HIV-infected patients with CD4 counts greater than or equal to 500 cells/&mgr;L, nadir CD4 counts greater than or equal to 250 cells/&mgr;L, and plasma viral loads less than 50 copies/mL for at least the past 12 months began a treatment interruption program. The event of interest for this study was the decrease of CD4 count below 350 cells/&mgr;L. Kaplan-Meier curves were used for all time-to-event analyses, and log-rank tests were used for comparison between groups in the univariate analysis. All variables with statistical association with CD4 T-cell loss were analyzed using multivariate Cox proportional hazards regression models. Results: Twenty-three percent of the patients had a decrease in CD4 count to less than 350 cells/&mgr;L. In the univariate analysis, only thymic volume was statistically significant with this event (P = 0.02). Nadir CD4 count nearly reached statistical significance. However, age, sex, HCV coinfection, CD4 count, T-cell receptor excision circle-bearing cells, and early viral load rebound did not show statistical differences. Thymic volume and CD4 T-cell loss were independently associated using Cox proportional hazards regression model (P = 0.04; relative risk, 0.76; 95% confidence interval, 0.59-0.99). Conclusions: In this study, we demonstrate for the first time that thymic volume predicts CD4 T-cell loss in patients with nadir CD4 count greater than or equal to 250 cells/&mgr;L under treatment interruption.

Effect of Hepatitis C Virus Coinfection on Humoral Immune Alterations in Naïve HIV-Infected Adults on HAART: A Three Year Follow-Up Study

Whether HAART allows complete recovery of humoral immune function in HIV-infected individuals is still controversial. Our objective was to study the effect of HAART on both B cell repopulation and hypergammaglobulinemia in 72 naïve patients, including 35 HCV-coinfected individuals, during 156 weeks on HAART. The possible role of HCV coinfection on the recovery of the humoral immune system was also investigated. At baseline, HCV-coinfected patients had greater circulant IgG levels than HIV-only-infected patients, while B cell count and CD21low B cell subpopulation were similar in both groups. During HAART, HIV-only-infected patients reached normal B cell counts and circulant IgG levels, while HCV-coinfected individuals did not. CD21low B cell subpopulation significantly decreased in both groups of patients at week 48 after the initiation of HAART compared to baseline. Thus, B cells remained continuously stimulated in HCV-coinfected patients and this stimulation seemed to be through a CD21-independent pathway.

Effect of the substitution of one nucleoside analogue by one non-nucleoside reverse transcriptase inhibitor over mitochondrial DNA levels.

Background:Long-term antiretroviral therapy is associated with several side effects, like mitochondrial toxicity related to nucleoside reverse transcriptase inhibitors (NRTIs). Our objective was to analyze the effect of the substitution of one NRTI by one non-nucleoside reverse transcriptase inhibitor (NNRTI) in the antiretroviral regime of HIV-1-infected patients who were on a regime containing either two NRTIs and one NNRTI, or one NRTI, one NNRTI and one protease inhibitor (PI), over mtDNA level. Decreasing NRTIs could increase mtDNA level.Methods:Fifteen HIV-1-infected patients were included in the study. As controls, 17 healthy individuals and 15 HIV-1-infected patients naïve for antiretroviral treatment were also analyzed. mtDNA level was quantified at baseline and after 48 weeks of treatment.Results:Control groups showed higher levels of mtDNA than the study group (p < 0.001). Among this latter group, no statistical differences between baseline and after 48 weeks were found. Naïve HIV-infected patients had lower mtDNA than healthy volunteers (p < 0.001). Two patients had two consecutive blips (low viral load increases) but they did not show NNRTI-related resistance mutations.Conclusions:This study shows that although this treatment was immunovirologically effective, mtDNA level did not increase at least after 48 weeks.