Laura Díaz

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.

Differential effects of phorbol-13-monoesters on human immunodeficiency virus reactivation

The persistence of latent reservoirs of HIV-1 represents a major barrier to virus eradication in patients treated with antiretrovirals. Prostratin is a non-tumor promoting 12-deoxyphorbol monoester capable of up-regulating viral expression from latent provirus and therefore is potentially useful for HIV adjuvant therapy and similar properties might be elicited by related non-tumor promoting phorboids. We have therefore investigated a series of phorbol 13-monoesters for their capacity to reactivate HIV latency. Using a Jurkat T cell line containing latent HIV proviruses, we found that prostratin and phorbol-13-stearate effectively activate HIV-1 gene expression in these latently infected cells, with phorbol-13-stearate being at least 10-fold more potent than prostratin, and its activity rapidly decreasing with a shortening of the acyl side chain. We further demonstrated that phorbol-13-stearate and prostratin stimulate IKK-dependent phosphorylation and degradation of IkappaBalpha, leading to activation of NF-kappaB. Moreover, prostratin, phorbol-13-hexanoate and phorbol-13-stearate also activate the JNK and ERK pathways. Studies with isoform-specific PKC inhibitors suggest that the classical PKCs play a prominent role in the responses elicited by phorbol-13-stearate. Nevertheless, this compound induces a translocation pattern of the PKC isotypes alpha and delta to cellular compartments distinctly different from that elicited by prostratin and PMA.

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.

Gene Therapy in HIV‐Infected Cells to Decrease Viral Impact by Using an Alternative Delivery Method

The ability of dendrimer 2G‐[Si{O(CH2)2N(Me)2+(CH2)2NMe3+(I−)2}]8 (NN16) to transfect a wide range of cell types, as well as the possible biomedical application in direct or indirect inhibition of HIV replication, was investigated. Cells implicated in HIV infection such as primary peripheral blood mononuclear cells (PBMC) and immortalized suspension cells (lymphocytes), primary macrophages and dendritic cells, and immortalized adherent cells (astrocytes and trophoblasts) were analyzed. Dendrimer toxicity was evaluated by mitochondrial activity, cell membrane rupture, release of lactate dehydrogenase, erythrocyte hemolysis, and the effect on global gene expression profiles using whole‐genome human microarrays. Cellular uptake of genetic material was determined using flow cytometry and confocal microscopy. Transfection efficiency and gene knockdown was investigated using dendrimer‐delivered antisense oligonucleotides and small interfering RNA (siRNA). Very little cytotoxicity was detected in a variety of cells relevant to HIV infection and erythrocytes after NN16 dendrimer treatment. Imaging of cellular uptake showed high transfection efficiency of genetic material in all cells tested. Interestingly, NN16 further enhanced the reduction of HIV protein 24 antigen release by antisense oligonucleotides due to improved transfection efficiency. Finally, the dendrimer complexed with siRNA exhibited therapeutic potential by specifically inhibiting cyclooxygenase‐2 gene expression in HIV‐infected nervous system cells. NN16 dendrimers demonstrated the ability to transfect genetic material into a vast array of cells relevant to HIV pathology, combining high efficacy with low toxicity. These results suggest that NN16 dendrimers have the potential to be used as a versatile non‐viral vector for gene therapy against HIV infection.

Bryostatin activates HIV-1 latent expression in human astrocytes through a PKC and NF-ĸB-dependent mechanism.

Multiple studies have shown that HIV-1 patients may develop virus reservoirs that impede eradication; these reservoirs include the central nervous system (CNS). Despite an undetectable viral load in patients treated with potent antiretrovirals, current therapy is unable to purge the virus from these latent reservoirs. To broaden the inhibitory range and effectiveness of current antiretrovirals, the potential of bryostatin was investigated as a latent HIV-1 activator. We used primary astrocytes, NHA cells, and astrocytoma cells U-87. Infected cells with HIV-1NL4.3 were treated with bryostatin alone or in combination with different inhibitors. HIV-1 production was quantified by using ELISA. Transcriptional activity was measured using luciferase reporter gene assays by using lipofectin. We performed cotransfection experiments of the LTR promoter with the active NF-κB member p65/relA. To confirm the NF-κB role, Western blot and confocal microscopy were performed. Bryostatin reactivates latent viral infection in the NHA and U87 cells via activation of protein kinase C (PKC)-alpha and -delta, because the PKC inhibitors rottlerin and GF109203X abrogated the bryostatin effect. No alteration in cell proliferation was found. Moreover, bryostatin strongly stimulated LTR transcription by activating the transcription factor NF-κB. Bryostatin could be a beneficial adjunct to the treatment of HIV-1 brain infection.

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.

Fluorescent benzofurazan-cholic acid conjugates for in vitro assessment of bile acid uptake and its modulation by drugs.

Fluorescent synthetic 7‐nitrobenzo‐2‐oxa‐1,3‐diazole (NBD) conjugates of cholic acid were prepared and characterized. Their photophysical properties make them suitable for monitoring uptake in freshly isolated rat hepatocytes using flow cytometry. This technique makes it possible to screen drug candidates for cholestatic (and thus hepatotoxic) liability.

Specific patterns of CD4‐associated immunosenescence in vertically HIV‐infected subjects

Vertical transmission of human immunodeficiency virus (HIV) represents an important world-wide health problem although the incidence in developed countries has been drastically reduced by the extensive use of highly active antiretroviral therapy. Vertically HIV-infected subjects have been exposed to the virus during the maturation of their immune systems and have suffered a persistent chronic activation throughout their lifetime; the consequences of this situation for their immune system are not fully understood. The objective of this study was to analyse immunosenescence-related parameters in different CD4 T-cell subsets. Fifty-seven vertically HIV-infected subjects and 32 age-matched healthy subjects were studied. Activation (HLA(-) DR(+) ), senescence (CD28(-) CD57(+) ) and proliferation (Ki67(+) ) were analysed on different CD4 T-cell subsets: naive (CD45RA(+) CD27(+) ), memory (CD45RO(+) CD27(+) ), effector memory (CD45RO(+) CD27(-) ) and effector memory RA (CD45RA(+) CD27(-) ). Compared with healthy subjects, vertically HIV-infected subjects showed increased naive and memory CD4 T-cell frequencies (p 0.035 and p 0.010, respectively) but similar frequencies of both effector subsets. Whereas naive CD4 T cells were not further altered, memory CD4 T cells presented increased levels of senescence and proliferation markers (p <0.001), effector memory CD4 T cells presented increased levels of activation, senescence and proliferation markers (p <0.001) and effector memory RA CD4 T cells presented increased levels of activation and senescence (p <0.001) compared with healthy subjects. Despite long periods of infection, vertically HIV-infected subjects show specific patterns of immunosenescence, revealing a preserved CD4 T-cell homeostasis for subset differentiation and distribution. Nevertheless, excepting the naive subpopulation, all subsets experienced some immunosenescence, pointing to uncertain consequences of the future aging process in these subjects.