T-cell phenotype and function following a first cART regimen containing either a protease inhibitor or a non-nucleoside reverse transcriptase inhibitor in HIV-infected late presenters: results from a retrospective, ex vivo study.

BACKGROUND: We aimed to comparatively assess darunavir/ritonavir (DRV/r) and efavirenz (EFV)-based first-line cART regimens in the reconstitution of T-cell phenotype and function in HIV-infected, late presenter subjects. METHODS: Retrospective, ex vivo study on stored peripheral blood mononuclear cell samples of cART-naive, HIV-infected individuals with CD4(+) T-cell counts <50>250/µl upon cART initiation with either DRV/r or EFV as third drugs of standard antiretroviral regimens. CD4(+) and CD8(+) T-cell maturation (CCR7/CD45RA) and proliferation (Ki67), CD8(+) T-cell activation (CD38/HLA-DR) as well as HIV- and cytomegalovirus (CMV)-specific responses (CD4/CD8/IL-2/IFN-γ) were studied by flow cytometry at baseline (T0), T3, T6 and T12 months. Soluble inflammatory markers (IL-6 and sCD14) were measured in plasma at T0 and T12. Wilcoxon and Mann-Whitney tests were used for statistics. RESULTS: A total of 19 patients started DRV/r and 15 EFV. Both regimens accounted for suppression of the HIV RNA load (<40 copies/ml), reconstitution of absolute CD4(+) T-cells and CD4(+)/CD8(+) T-cell ratio. All study participants displayed a significant decrease of activated HLA-DR(+)CD38(+) CD8(+) T-cells at all study time points, yet no differences were found between study groups in T-cell activation and maturation phenotype. From a functional standpoint, only individuals receiving DRV/r displayed transitory recovery of HIV-specific IL-2(+)IFN-γ(-) CD4(+) T-cells (T3: P=0.006) and IL-2(-)IFN-γ(+) CD8(+) T-cells (T3: P=0.032). CONCLUSIONS: DRV/r- and EFV-based regimens have an equal effect on T-cell phenotype and function in HIV late presenters. A temporary restoration of HIV-specific T-cell immunity early in the course of therapy with DRV/r possibly implies a more effective control over HIV in the first months following a PI/r-based regimen, even at late stage of disease.

Role of in vitro stimulation with lipopolysaccharide on T-cell activation in HIV-infected antiretroviral-treated patients.

We investigated the effect of LPS in vitro stimulation on T-cell activation in HIV-infected patients with different CD4+ recovery on HAART. PBMCs from 30 HIV-positive, HAART-treated, aviremic individuals with different CD4+ reconstitution (Low Responders: CD4+ < 350/µL; Intermediate Responders: CD4+ 350-599/µL; High Responders: CD4+ ≥ 600/µL) were cultured with LPS and the proportion of HLA-DR/CD38- and Ki67-expressing CD4+/CD8+ T-cells was measured (flow cytometry). Upon LPS stimulation, significantly higher CD4+ and CD8+HLA-DR+ cells were shown in LR and IR versus HIV-negative controls. While no differences in the proportion of LPS-stimulated CD4+CD38+ cells were recorded amongst HIV-positive subgroups, CD8+CD38+ cells were more elevated in patients with lower CD4+ recovery on HAART (i.e., LR and IR). Upon in vitro LPS stimulation, HLA-DR and CD38 expression on T-cells are differentially regulated. While HLA-DR induction reflects impaired CD4+ reconstitution on HAART, cell-surface CD38 expression is increased only on CD8+ T-cells, allowing to speculate that the sole induction of CD38 on CD4+ cells may not be sufficient to depict LPS-driven immune activation in HIV.

Sequencing of bacterial microflora in peripheral blood: our experience with HIV-infected patients.

The healthy gastrointestinal tract is physiologically colonized by a large variety of commensal microbes that influence the development of the humoral and cellular mucosal immune system. Microbiota is shielded from the immune system via a strong mucosal barrier. Infections and antibiotics are known to alter both the normal gastrointestinal tract barrier and the composition of resident bacteria, which may result in possible immune abnormalities. HIV causes a breach in the gastrointestinal barrier with progressive failure of mucosal immunity and leakage into the systemic circulation of bacterial bioproducts, such as lipopolysaccharide and bacterial DNA fragments, which contribute to systemic immune activation. Microbial translocation is implicated in HIV/AIDS immunopathogenesis and response to therapy. We aimed to characterise the composition of bacteria translocating in peripheral blood of HIV-infected patients. To pursue our aim we set up a PCR reaction for the panbacteric 16S ribosomial gene followed by a sequencing analysis. Briefly, whole blood from both HIV-infected and healthy subjects is used. Given that healthy individuals present normal intestinal homeostasis no translocation of microflora is expected in these patients. Following whole blood collection by venipuncture and plasma separation, DNA is extracted from plasma and used to perform a broad range PCR reaction for the panbacteric 16S ribosomial gene. Following PCR product purification, cloning and sequencing analyses are performed.

Microbial translocation predicts disease progression of HIV-infected antiretroviral-naive patients with high CD4+ cell count.

OBJECTIVES: We investigated the significance of microbial translocation measured on average 3 years after HIV seroconversion in driving disease progression in HIV untreated patients with high CD4(+) cell count. DESIGN: We included ICONA patients with documented last HIV-negative and first HIV-positive test, at least one plasma sample stored while antiretroviral therapy (ART)-naive and CD4(+) cell count greater than 200 cells/µl. METHODS: Microbial translocation [lipopolysaccharide (LPS), sCD14 and EndoCAb] and immune activation (IL-6 and TNF-α) were measured. Correlation between immune activation, microbial translocation, CD4(+) and plasma HIV-RNA was evaluated by linear regression and nonparametric Spearman's rho. The independent predictive value of these markers on time to progression to the combined endpoint of AIDS, death, CD4(+) cell count less than 200 cells/µl or start of antiretroviral therapy (ART) was assessed using survival analysis. RESULTS: We analysed 1488 biomarker measures from 379 patients. A median of 3.1 years after the estimated seroconversion date [interquartile range (IQR) 1.6-5.4], median (IQR) markers values were LPS, 110 pg/ml (IQR 75-215), sCD14, 3.3 µg/ml (2.2-4.8), IL-6, 1.1 pg/ml (0.6-1.9) and TNF-α, 2.4 pg/ml (1.8-3.4). Two hundred and sixty progression events were recorded over a median of 1.6 years from the first sample (2% AIDS, 84% ART initiation, 12% CD4(+) cell count less than 200 cells/µl and 2% death). LPS was the only biomarker associated with this primary composite outcome independently of age, HIV-RNA and CD4(+) (relative hazard = 1.40 per loge higher, 95% confidence interval 1.18-1.66, P < 0.001). CONCLUSION: Circulating LPS in the first years of chronic HIV infection is a strong predictor of disease progression independent of CD4(+) cell count and HIV viraemia and may be considered a candidate biomarker for HIV monitoring and evaluation in clinical trials.

Reduced CD127 expression on peripheral CD4+ T cells impairs immunological recovery in course of suppressive highly active antiretroviral therapy.

Inefficient immune recovery under highly active antiretroviral therapy (HAART) represents a clinical issue. Twenty-seven of 121 HIV+ naïve patients became immunological nonresponders (INRs) and 55 introduced therapy late [very late treated (VLT)]. INR displayed older age, lower CD4(+) cell counts, down-regulation of CD127(+)CD4(+) and higher apoptotic CD95(+)CD8(+). VLT also showed higher activated CD38(+)CD8(+)%. The only factor associated with INR status was CD127(+)CD4(+)%. INR showed lower baseline interleukin (IL)-7 levels and a reduced expression of IL-7R (CD127(+)) on naïve and memory T-cells, reaching significance in memory CD127(+)CD45(+)R0(+)CD4(+). These results suggest a possible role for the IL-7/IL-7R system in the pathogenesis of poor immunological recovery during HAART.

Sudden cardiac death in a young HIV-positive man on effective antiretroviral therapy.

We describe the case of a young HIV-positive man on effective HAART with excellent viro-immunological control who presented a massive cardiac infarction. Despite the presence of clinical risk factors for cardiovascular disease, the patient had normal arterial carotid IMT values, known to be strong predictors of atherosclerosis and stroke. Interestingly, parameters of T-cell activation (CD8+CD38+) were shown to increase just before the onset of myocardial infarction. As T-cell activation is known to mediate atherosclerosis, the authors suggest that surrogate immunologic markers should be identified to better assess cardiovascular risk in the setting of HIV infection.

Microbial translocation is associated with sustained failure in CD4+ T-cell reconstitution in HIV-infected patients on long-term highly active antiretroviral therapy.

Patients with inefficient CD4+ T-cell recovery on virogically suppressive highly active antiretroviral therapy constitute a major clinical hurdle given the threat of HIV/AIDS disease progression. We show heightened circulating lipopolysaccharide associated with plasma enterobacterial DNA and highly activated Ki67+CD4+CD8+ in 24 immunologic-nonresponders (CD4+ T-cell < or = 200; HIV-RNA < or = 50) compared with 11 full responders (CD4+ T-cell > or= 400; HIV-RNA < or = 50). These data provide novel insight into INRs pathogenesis, since they correlate augmented systemic translocation of microbial bioproducts with T-cell hyperactivation.