Discordant responses to HAART in HIV-1 patients: the need to focus on intervention

High T-cell immune activation and immune exhaustion among individuals with suboptimal CD4 recovery after 4 years of antiretroviral therapy in an African cohort

BACKGROUND

Antiretroviral therapy (ART) partially corrects immune dysfunction associated with HIV infection. The levels of T-cell immune activation and exhaustion after long-term, suppressive ART and their correlation with CD4 T-cell count reconstitution among ART-treated patients in African cohorts have not been extensively evaluated.

METHODS

T-cell activation (CD38+HLA-DR+) and immune exhaustion (PD-1+) were measured in a prospective cohort of patients initiated on ART; 128 patient samples were evaluated and subcategorized by CD4 reconstitution after long-term suppressive treatment: Suboptimal [median CD4 count increase 129 (-43-199) cells/μl], N = 34 ], optimal [282 (200-415) cells/μl, N = 64] and super-optimal [528 (416-878) cells/μl, N = 30].

RESULTS

Both CD4+ and CD8 T-cell activation was significantly higher among suboptimal CD4 T-cell responders compared to super-optimal responders. In a multivariate model, CD4+CD38+HLADR+ T-cells were associated with suboptimal CD4 reconstitution [AOR, 5.7 (95% CI, 1.4-23, P = 0.014)]. T-cell exhaustion (CD4+PD1+ and CD8+PD1+) was higher among suboptimal relative to optimal (P < 0.001) and super-optimal responders (P < 0.001). T-cell exhaustion was significantly associated with suboptimal responders [AOR, 1.5 (95%CI, 1.1-2.1), P = 0.022].

CONCLUSION

T-cell activation and exhaustion persist among HIV-infected patients despite long-term, sustained HIV-RNA viral suppression. These immune abnormalities were associated with suboptimal CD4 reconstitution and their regulation may modify immune recovery among suboptimal responders to ART.

Conserved T cell and natural killer cell function in treatment-experienced adults receiving tenofovir plus didanosine as nucleoside reverse transcription inhibitor backbone

Anti-retroviral treatment (ART) usually results in efficient control of virus replication and in immune reconstitution. Among potential adverse effects, impairment of immune responses in terms of CD4(+) T cell counts has been attributed to some ART regimens, as with didanosine-tenofovir. We studied the functional integrity of adaptive and innate immunity during didanosine-tenofovir-containing ART. Two groups of extensively pretreated patients completing at least 48 weeks of ART containing either lamivudine-didanosine (n = 21) or tenofovir-didanosine (n = 25) were identified. In addition to standard clinical immune and virological parameters, we performed a flow cytometric analysis of natural killer (NK) cells, of memory and naive CD4(+) T cells and of T cell receptor alphabeta(+) T cells co-expressing inhibitory NK receptors. Functional analysis consisted in specific and total interferon-gamma production by NK cells and of recall antigen proliferation of peripheral blood mononuclear cells. Comparable clinical immunological reconstitution and virological control were confirmed in the two groups of patients in the absence of clinically relevant adverse effects. The proportion of CD4(+)CD45RA(+) T cells and of functionally inhibited killer immunoglobulin-like receptor T cell receptor alphabeta(+) cells, the proliferation to recall antigens as well as NK cell phenotype and function as determined by interferon-gamma production in patients treated with tenofovir-didanosine were comparable to those treated with a different regimen. Thus, no differences in functional innate or adaptive immune reconstitution are detected in drug-experienced human immunodeficiency virus-infected patients on tenofovir-didanosine nucleoside reverse transcription inhibitor regimens.

The absence of CD4+ T cell count recovery despite receipt of virologically suppressive highly active antiretroviral therapy: clinical risk, immunological gaps, and therapeutic options

Up to 30% of human immunodeficiency virus (HIV)-infected patients who are receiving long-term highly active antiretroviral therapy do not exhibit a marked increase in the CD4(+) T cell count, despite achieving complete suppression of the HIV load. These patients are referred to as "immunological nonresponders." When treating immunological nonresponders, the practicing clinician has several questions, including questions about the clinical risk associated with persistent immunodeficiency and about possible approaches to treatment that would provide clinical and immunological benefits. However, tentative answers to these questions require investigations of the mechanisms that underlie the lack of immune recovery, because only the deepest comprehension of the immunological gaps underlying functional defects will allow administration of highly targeted and efficacious treatment strategies. The aim of our review is to provide a thorough assessment of the clinical implications of a lack of increase in the CD4(+) T cell count in immunological nonresponders, to examine the immunological gaps limiting recovery of the CD4(+) T cell count, and to note possible therapeutic avenues, which may offer clinicians guidance regarding how to most efficaciously treat these critical patients.