Decreased CD4 and increased CD8 counts with T cell activation is associated with chronic helminth infection

We have previously reported the presence of marked immune dysregulation with a dominant Th2 profile, in a population of Ethiopian immigrants (ETH) in Israel heavily infected with helminths. In order to characterize better this immune dysregulation we studied by flow cytometry the expression of several activation markers on peripheral T cell populations, and lymphocyte apoptosis, in blood samples obtained from 63 ‘new’ ETH (recently arrived), 18 ‘old’ ETH (> 5 years since immigration) and 34 non-Ethiopian Israelis. The main findings in the ‘new’ ETH group in comparison with the non-Ethiopian controls were: (i) decreased CD4 and increased CD8 lymphocyte counts; (ii) elevated levels of activated T cells (CD3, CD4 and CD8) expressing HLA-DR; (iii) decreased levels of ‘naive’ CD4⁺ cells (CD45RA⁺), with increased levels of ‘memory’ CD4⁺ cells (CD45RO⁺); (iv) decreased numbers of CD28⁺ CD8⁺ lymphocytes; (v) marked increase in lymphocyte apoptosis. These T cell alterations and activation profile remained unchanged in 10 ‘new’ ETH in whom the helminth infections persisted for 6–11 months. In contrast, in 18 ‘old’ ETH, without helminth infections, the T cell activation profile was within the normal range. These findings suggest that chronic helminth infections may have a profound effect on the immune system of the host that disappears after eradication of these infections and adjustment to the new environment. It should therefore be taken into consideration for every immunomodulation therapy and especially in vaccine design and trials, in regions endemic for helminth infections.     

Persistent apoptosis in HIV-1-infected individuals receiving potent antiretroviral therapy is associated with poor recovery of CD4 T lymphocytes

CD4 T-cell depletion in HIV-1 infection is partly the result of T-cell apoptosis. Spontaneous apoptosis (SA) and apoptosis markers Fas-associated death-domain-like IL-1 beta converting enzyme (FLICE)-like inhibitory protein (FLIP), Bcl-2, TRAIL (tumor necrosis factor-related apoptosis-inducing ligand), TRAIL receptor 1, and Fas were determined in 55 HIV-1 infected persons treated with highly active antiretroviral therapy (HAART) for 48 months. Despite suppressive HAART, SA remained elevated. Increased SA of peripheral blood mononuclear cells (PBMCs) and CD8 T lymphocytes and increased TRAIL receptor 1 expression strongly predicted a poorer recovery of CD4 T-cell count. HAART did not significantly alter anti-or proapoptotic markers in cultured PBMCs and T lymphocytes. The significant relationship between residual T-lymphocyte apoptosis and CD4 T-cell recovery suggests that persistent apoptosis may impede immune restoration.     

Response to highly active antiretroviral therapy at 6 months and long-term disease progression in HIV-1 infection

OBJECTIVE: To compare the long-term prognostic significance of different definitions of immunologic and virologic responses to highly active antiretroviral therapy (HAART) at 6 months. METHODS: This was a prospective study conducted in 68 French hospitals. HAART was initiated in 2236 protease inhibitor-naive patients included in the French Hospital Database on HIV. Multivariate Cox proportional hazard models measuring time from 6 months after starting HAART were used to compare the strength of the association between different definitions of immunologic and virologic responses at 6 months and subsequent progression to AIDS or death. The Akaike's Information Criteria were used to identify the most appropriate model. RESULTS: During a median follow-up of 58 months, 325 patients experienced an AIDS-defining event or died. The model that fitted best was the model in which the CD4 cell count and plasma HIV-1 RNA values attained at 6 months were considered. The risk of clinical progression at 5 years ranged from 7% (95% confidence interval [CI]: 4-10) in patients whose CD4 cell count at 6 months was >or=350 cells/microL and whose HIV-1 RNA concentration was <3 log10 copies/mL to 63% (95% CI: 52-75) in patients whose CD4 cell count at 6 months was <100 cells/microL and whose HIV-1 RNA concentration was >or=5 log10. CONCLUSIONS: Plasma HIV-1 RNA concentration and CD4 cell count should be taken into account independently when evaluating early response to treatment. The persistent impact of early response on clinical progression at 5 years emphasizes the major importance of the success of first-line HAART.     

Reconstitution of CD4+ T cell responses in HIV-1 infected individuals initiating highly active antiretroviral therapy (HAART) is associated with renewed interleukin-2 production and responsiveness

Reconstitution of functional CD4(+) T cell responsiveness to in vitro stimuli is associated with continuous highly active antiretroviral therapy (HAART). Thirty-six antiretroviral naive patients received HAART over 16 weeks. Antigen-specific, mitogen and interleukin (IL)-2 induced lymphocyte proliferative responses and specific IL-2 and IL-4 production were assessed at each time-point, together with quantification of HIV-1 RNA load and lymphocyte populations. Reconstitution of recall responses was limited largely to persistent antigens such as Herpes simplex virus and Candida, rather than to HIV-1 or neo-antigens. Recall antigens, mitogens and IL-2-induced renewed responses were associated with in-vitro production of IL-2, but not IL-4. Differential responsiveness to low versus high concentration IL-2 stimulus increases in a stepwise manner, suggesting normalization of IL-2 receptor expression and improved functionality. These increases in in-vitro proliferative responses thus probably reflect short lived effector clones, driven by ongoing antigenic stimulus associated with persisting long-term organisms. In this context non-responsiveness to HIV-1 antigens suggests ongoing HIV-1 specific clonal T cell anergy.     

Immune restoration after treatment of HIV-1 infection with highly active antiretroviral therapy (HAART)

The availability of combination antiretroviral therapy (HAART) has been associated with dramatic decreases in HIV-related morbidity and mortality. These clinical benefits are probably mediated by a decrease in HIV-1 replication and an increase in the number and function of peripheral blood CD4+ lymphocytes. Despite many years of maintaining plasma HIV-1 RNA levels below the limits of detection, many patients do not achieve normal CD4+ lymphocyte counts. A larger proportion of patients who delay HAART for longer have incomplete numerical CD4+ restoration compared to patients who start therapy earlier. Even in patients who normalize their CD4+ lymphocytes insert counts, immune function remains impaired among those who delay HAART for longer periods. Whether subclinical immune deficiency will be associated over longer periods of follow-up with adverse clinical outcomes such as an increased number of infections and malignancies remains to be determined. If prolonged subclinical immunodeficiency is associated with adverse outcomes, the use of immune-based therapies may benefits patients while helping us ascertain the residual deficits responsible for incomplete immune restoration.     

Increased lipodystrophy is associated with increased exposure to highly active antiretroviral therapy in HIV-infected children

OBJECTIVE: To assess body composition changes in HIV-infected children receiving highly active antiretroviral therapy (HAART). METHODS: Thirty-seven HIV-positive children were enrolled. Dual-energy X-ray absorptiometry (DXA) scans were performed in all HIV-infected children at baseline and after an additional 12 months of HAART and in 54 matched (for sex, age, body mass index [BMI], and pubertal stage) healthy controls. Abdominal MRI was performed in 14 of 37 HIV-positive children at baseline and in 28 of 37 HIV-positive children after additional 12 months of HAART. RESULTS: During the study period, mean HAART exposure increased from 39.3 to 50.9 months and the number of HIV-infected children with clinical lipodystrophy (LD) increased from 6 to 8, whereas mean BMI, CD4 percentage, and percentage of HIV-infected children with HIV RNA <50 copies/mL did not change. DXA scans showed an increase in lean mass, peripheral fat loss, and central fat accumulation in all HIV-infected children. As compared with controls, 70% and 84% of HIV-infected children showed DXA-detectable LD at baseline and at 12 months of follow-up, respectively. Mixed LD and central fat accumulation were the most common LD phenotype. At baseline and at 12 months of follow-up, intra-abdominal adipose tissue (IAT) was greater than in controls in 33% and 35% of HIV-infected children, and it was greater in those with LD than in those without. Peripheral fat loss and IAT content were associated with duration of HAART and were independent of immunologic stage of disease and immunologic response. CONCLUSIONS: Changes in body composition related to LD in HAART-treated children are frequent, precocious, and progressive. Duration of HAART negatively influences visceral adiposity and peripheral fat loss.     

Decreased T cell apoptosis and T cell recovery during highly active antiretroviral therapy (HAART)

T cell apoptosis represents a common mechanism of T cell depletion in HIV-1-infected individuals reflecting maturational and functional T cell abnormalities either directly or indirectly induced by the virus. In the present study, the effects of highly active antiretroviral therapy (HAART) on the spontaneous apoptosis of distinct T cell subsets were investigated during a 6-month follow-up in a cohort of HIV-1-infected individuals with CD4(+) cell counts between 100 and 500 cells/microliter and plasma HIV-1 RNA levels >/=10, 000 copies/ml. We determined that the rapid and sustained increase of both naive (CD45RA(+)CD62L(+)) and memory (CD45R0(+) and CD45RA(+)/CD62L(-)) CD4(+) and, to as lesser extent, CD8(+) T cells in peripheral blood was associated with a significant decrease of apoptotic CD4(+) and CD8(+) as well as CD3(+)CD4(-)CD8(-) T cells. Among CD4(+) lymphocytes, at enrollment, the highest frequency of apoptotic cells was observed within the memory compartment, as defined by CD45R0 expression. During HAART, however, the frequency of CD4(+)CD45R0(+) apoptotic T cells progressively decreased in association with a significant downregulation of surface activation markers that indicated decreased levels of systemic immune stimulation. These results indicate that effective viral suppression can contribute to progressive normalization of maturational and functional T cell abnormalities responsible for the high levels of T cell apoptosis in HIV-1-infected individuals. This, in turn, may contribute to a reduced rate of T cell loss and immune reconstitution during HAART.     

CD4+ T-lymphocyte nadir and the effect of highly active antiretroviral therapy on phenotypic and functional immune restoration in HIV-1 infection

To evaluate the effects of the timing of highly active antiretroviral therapy (HAART) on immune reconstitution, we compared lymphocyte subpopulations and lymphocyte proliferation (LP) in response to Candida albicans, cytomegalovirus, HIV p24, Mycobacterium avium complex, pokeweed mitogen, streptokinase, and tetanus toxoid in 43 patients with pretherapy advanced, moderately advanced, and early chronic HIV-1 infection. All patients had recent CD4⁺ T-cell counts >450/μl and HIV RNA <400 copies/ml for >12 months. CD4⁺ nadirs were positively correlated with recent numbers of CD4⁺ T-cells (P < 0.001), memory cells (P < 0.001), and na??ve CD4⁺ T-cells (P < 0.05) and CD4⁺ CD28⁺ T-lymphocytes (P < 0.05) and were negatively correlated with recent CD8⁺ T-lymphocyte counts (P < 0.05). Only CD4⁺ na??ve T-cells normalized when HAART was initiated at lower CD4⁺ T-cell levels. Fifty-three percent of patients had LP responses to HIV p24 antigen. While LP responses to prevalent antigens were usually present, responses to tetanus toxoid were more common with higher CD4⁺ T-lymphocyte nadirs (P < 0.05). Delaying HAART may limit phenotypic and functional immune restoration in HIV-1 infection.     

CCR5 and CXCR4 expression on memory and naive T cells in HIV-1 infection and response to highly active antiretroviral therapy

OBJECTIVE: To measure CCR5 and CXCR4 chemokine receptor expression on CD4 and CD8 T cells in HIV-1 infection and to relate levels to the distribution of CD45RO memory and CD45RA-naive subsets, measures of disease activity, and response to highly active antiretroviral therapy (HAART). DESIGN: Fourteen untreated HIV-1-infected patients, 18 patients at 3-to 4-weeks after beginning HAART, and 35 uninfected control subjects were studied. METHODS: Four-color cytofluorometry with appropriate conjugated monoclonal antibodies (mAbs) was performed to define CD45RA and CD45RO subsets of CD4 and CD8 T cells and measure their expression of CCR5, CXCR4, and CD38. RESULTS: HIV-1-infected patients had higher CCR5 levels and lower CXCR4 levels on CD4 and CD8 T cells and their CD45RO/CD45RA subsets than control subjects did. However, CCR5 elevation was statistically significant only for CD4 T cells and their subsets, and CXCR4 depression was significant for CD8 T cells and their subsets (and for CD4:CD45RO cells). The elevation of CCR5 and depression of CXCR4 were not due to shifts in CD45RO/CD45RA subset proportions but to upregulation or downregulation within the subsets. CCR5 elevation on CD4 T cells was significantly restored toward normal by HAART, but the CXCR4 depression was not. CCR5 expression but not CXCR4 expression correlated with other measures of immunodeficiency (CD4 T-cell levels), active infection (viral load), and cellular activation (CD38). CONCLUSIONS: CCR5 elevation is a concomitant of immune activation and viral replication that occurs in HIV-1 infection, but the relation of CXCR4 depression to severity of infection, disease progression, and response to therapy remains undefined.     

Increases in T cell telomere length in HIV infection after antiretroviral combination therapy for HIV-1 infection implicate distinct population dynamics in CD4+ and CD8+ T cells.

Changes in mean telomeric terminal restriction fragment (TRF) length were examined as a marker for cellular replicative history in HIV-1-infected individuals after institution of anti-retroviral therapy (ART). Increases in mean T cell TRF lengths were observed in most patients following therapy; however, the contribution of individual T cell subsets was complex. An elongation of CD8+ T cell TRF was nearly uniformly observed while changes in mean TRF length in CD4+ T cells were heterogeneous as, despite potent suppression of viral replication, CD4 cell telomeres recovered in some patients, yet continued to decline in others. Increases in CD8 cell TRF correlated with decreased memory cells, suggesting a negative selection in the periphery for CD8 cells with extensive replicative history. In contrast, increases in CD4+ T cell TRF length correlated with increases in naive cell subsets, suggesting that the CD4+ T cell TRF increase may reflect a thymic contribution in some patients. These are the first increases in somatic cell telomere length in a population of cells observed in vivo, and the findings are compatible with therapy-induced reconstitution of the lymphoid compartment with cells having a more extensive replicative potential. These findings further distinguish lymphocytes from other somatic cell populations where only decreases in TRF over time have been noted. Thus, institution of ART in persons with moderately advanced HIV-1 disease reveals distinct population dynamics of CD4 and CD8 T cell subsets and also shows that the lymphocyte replicative history is dynamic.     

Modifications of HIV-1 DNA and provirus-infected cells during 24 months of intermittent highly active antiretroviral therapy

BACKGROUND: Few data have been reported on the dynamics of HIV-1 DNA during intermittent highly active antiretroviral therapy (HAART). In this study, we measured cell-associated HIV-1 DNA and provirus-infected cells during the Istituto Superiore di Sanità-Pulsed Antiretroviral Therapy (ISS-PART) clinical trial. METHODS: HIV-1 DNA was measured by real-time polymerase chain reaction (PCR) in the peripheral blood mononuclear cells (PBMCs) of 37 subjects enrolled in the ISS-PART, a randomized clinical trial comparing 24 months of intermittent (arm B) versus continuous (arm A) HAART in chronic HIV infection. In 14 subjects, the number of provirus-infected cells was also measured at baseline and at month 24. RESULTS: At baseline, the number of HIV-1 DNA copies/10(6) PBMCs was similar in arm B (mean +/- SD: 121 +/- 172, median = 35) and arm A (mean +/- SD: 107 +/- 153, median = 10) (P = not significant [n.s.]). No significant variations occurred over time; at 24 months, the HIV-1 DNA level was 77 +/- 28 (median = 30) copies/10(6) PBMCs in arm B and 166 +/- 321 copies/10(6) PBMCs (median = 10) in arm A (P = n.s.). At baseline, the provirus-infected cell counts were 85 +/- 98 (median = 50) cells/10(6) PBMCs in arm B and 92 +/- 113 (median = 50) cells/10(6) PBMCs in arm A (P = n.s.), with no variations at 24 months. CONCLUSIONS: These findings suggest that the intermittent schedule of the ISS-PART has no major impact on viral reservoirs, at least in a midterm follow-up.     

T cell proliferation and apoptosis in HIV-1-infected lymphoid tissue: impact of highly active antiretroviral therapy.

T cell turnover was studied in situ in tonsillar lymphoid tissue (LT) from HIV-1-infected individuals during 48 weeks of highly active antiretroviral therapy (HAART) and compared to that of HIV-1-negative controls. Prior to therapy, CD4 cell proliferation (%CD4+ Ki67+) and apoptosis (%CD4+ TUNEL+) were increased in HIV-1-infected LT and both parameters correlated with tonsillar viral load. CD8 cell proliferation (%CD8+ Ki67+) was increased 4- to 10-fold, mainly in the germinal centers. Apoptotic CD8+ T cell levels (%CD8+ TUNEL+) were raised preferentially in the tonsillar T cell zone. The frequency of CD8+ Ki67+ and CD8+ TUNEL+ T cells correlated with tonsillar viral load and with the fraction of CD8(+) T cells expressing activation markers. During HAART, CD4 cell turnover normalized while CD8 cell turnover was dramatically reduced. However, low level viral replication concomitant with slightly elevated levels of CD8 cell turnover indicated a persistent cellular immune response in LT. In conclusion, enhanced T cell turnover may reflect effector cells related to HIV-1 infection.     

Correlation between CD4 T-cell counts and HIV-1 RNA plasma levels in HIV-1 patients receiving highly active antiretroviral therapy (HAART)

The prognostic value of plasma HIV-1 RNA baseline levels in patients who are going to receive HAART has been recently questioned. In the present study the authors correlated the baseline counts of viremy and CD4 with the viral suppression induced by HAART in an ongoing cohort of HIV-1 positive patients. Data resulting from the study suggest that the HAART effect on CD4 T-cells depends both on the immunological status before starting therapy and on the degree of viral suppression. After briefly discussing about the possible causes of disconnection between CD4 T-cells count and plasma HIV-1 RNA levels, authors conclude that the viral suppression is the desired goal of antiretroviral treatment and that the maximum effect of HAART can be achieved by carefully clinically evaluating patients and individuating the best therapy.     

Functional restoration of human immunodeficiency virus and Epstein-Barr virus-specific CD8(+) T cells during highly active antiretroviral therapy is associated with an increase in CD4(+) T cells

To investigate the effect of highly active antiretroviral therapy (HAART) on HIV- and Epstein-Barr virus (EBV)-specific CD8(+) T cells, total number and function of these cells was determined in 16 HIV-infected individuals using tetrameric HLA-peptide complexes and IFN-gamma ELISPOT assays after peptide stimulation, respectively. HAART induced a significant decrease in HIV-specific tetramer(+) T cells, whereas EBV-specific tetramer(+) T cells did not change. In addition, individuals who temporarily failed on therapy showed a temporary increase in the number of HIV-specific T cells, suggesting that differences in the pool size of antigen-specific T cells was determined by the presence of antigen. Interestingly, there was an increase in the ratio of IFN-gamma-producing T cells per total number of both HIV- and EBV-specific T cells in the majority of individuals, suggesting that the function of virus-specific T cells is improved in individuals successfully treated with HAART. Despite this relative functional improvement of EBV-specific T cells, no significant changes were observed in EBV load. In four subjects who temporarily failed on HAART, the percentage of IFN-gamma-producing T cells, both for HIV and EBV, paralleled CD4(+) T cell kinetics, suggesting that function seems to be related to differences in CD4(+) T cell numbers. Overall, these data indicate that HAART improves the antigen responsiveness of both HIV- and EBV-specific T cells, which is associated with an increase in CD4(+) T cells.