Positive effects of combined antiretroviral therapy on CD4+ T cell homeostasis and function in advanced HIV disease

Changes in human immunodeficiency virus type 1 virus load during mobilization and harvesting of hemopoietic progenitor cells

Genetic modification of hemopoietic progenitor cells ex vivo, followed by the infusion of the genetically modified cells into the human immunodeficiency virus-1 (HIV-1) infected donor, has been proposed as a treatment for HIV-1 infection. The current study was undertaken to evaluate the effect of hemopoietic stem cell mobilization and harvesting on HIV-1 replication in persons with HIV-1 infection. Eighteen HIV-1–infected persons received recombinant granulocyte colony-stimulating factor (G-CSF; Filgrastim) 10 μg/kg per day, for 7 days. On days 4 and 5, peripheral blood mononuclear cells were harvested by leukapheresis. The CD4+ lymphocyte count at entry was >500/μL for 6 subjects, 200 to 500/μL for 6 subjects, and <200/μL for 6 subjects. For 9 of 18 subjects, plasma HIV-1 RNA levels increased 4- to 100-fold (>0.6 log10) above baseline between days 4 and 7 and returned to baseline by day 27. Significant increases of plasma HIV-1 RNA levels occurred in 5 subjects despite 3-drug antiretroviral therapy. Changes in CD4+ and CD34+ cells during mobilization and harvesting were similar in all subjects whether they had or did not have increased plasma HIV-1 RNA levels. Thus, mobilization and harvesting of bone marrow progenitor cells from persons infected with HIV-1 induced a transient increase in viral replication in some patients but was not associated with adverse effects. (Blood. 2000;95: 48-55)

T-cell division in human immunodeficiency virus (HIV)-1 infection is mainly due to immune activation: a longitudinal analysis in patients before and during highly active antiretroviral therapy (HAART)

In human immunodeficiency virus (HIV)-1 infection, highly increased T-cell turnover was proposed to cause exhaustion of lymphocyte production and consequently development of AIDS. Here, we investigated cell proliferation, as measured by expression of the Ki-67 nuclear antigen, in peripheral blood CD4+ and CD8+ lymphocyte subpopulations before and during highly active antiretroviral therapy (HAART). In untreated HIV-1 infection, both the percentage and number of Ki-67+CD4+ and CD8+ lymphocytes were significantly increased, compared with values obtained from healthy individuals. A more than 10-fold increase in the percentage of dividing naive CD4+ T cells in the blood was found when the number of these cells were below 100 per μL.. HAART induced an immediate decline in Ki-67 antigen expression, despite often very low CD4+ T-cell numbers, arguing against increased proliferation being a homeostatic response. After approximately 24 weeks of HAART treatment, a transient increase in the number of proliferating cells was seen, but only in the CD4+CD27+ memory pool. In the CD8+ T-cell compartment, the number of dividing cells was elevated 20- to 25-fold. This increase was most notable in the CD27+ CD 45RO+ and CD27−CD45RO+ memory CD8+ T-cell pool, corresponding with the degree of expansion of these subsets. Reduction of plasma HIV-RNA load by HAART was accompanied by a decrease in numbers and percentages of dividing cells in all CD8+T-cell subsets. Taken together, our results indicate that peripheral T-cell proliferation is a consequence of generalized immune activation. (Blood. 2000;95:249-255)

Immune reconstitution in the HAART era, Part 1: Immune abnormalities in HIV/AIDS

Highly active antiretroviral therapy (HAART) has dramatically altered the course of HIV infection. HAART has been associated with a substantial decrease in HIV-related morbidity and mortality and an improved quality of life for many persons living with HIV/AIDS. This improvement is due to suppression of viral replication and subsequent repletion of CD4+ T lymphocytes. However, it is not known if HAART can restore the deficits in immune function that are induced by HIV infection, such as anergy and disturbances in cellular phenotypes. In this first part of a two-part series, the immune abnormalities associated with HIV infection will be reviewed, and the concept of immune reconstitution will be introduced. In Part 2, the clinical significance of immune reconstitution will be discussed.

Adrenaline-induced mobilization of T cells in HIV-infected patients

The present study aimed to investigate lymphocyte mobilization from peripheral cell reservoirs in HIV-infected patients. Nine HIV-infected patients on stable highly active anti-retroviral therapy (HAART), eight treatment-naive HIV-infected patients and eight HIV- controls received a 1-h adrenaline infusion. The adrenaline infusion induced a three-fold increase in the concentration of lymphocytes in all three groups. All HIV-infected patients mobilized significantly higher numbers of CD8+ cells but less CD4+ cells. All subjects mobilized CD45RA+CD62L+ and CD8+CD28+ cells to a lesser extent than CD45RO+CD45RA- and CD8+CD28-cells. Furthermore, high numbers of CD8+CD38+ cells were mobilized only in the HIV-infected patients. It was therefore predominantly T cells with an activated phenotype which were mobilized after adrenaline stimulation. It is concluded that the HIV-associated immune defect induced an impaired ability to mobilize immune-competent cells in response to stress stimuli. Furthermore, the study does not support the idea that CD4+ T cells are trapped in lymph nodes by HIV antigens, because untreated and HAART-treated HIV-infected patients mobilized similar numbers of CD4+ T cells. Finally, no evidence was found for the existence of a HAART-induced non-circulating pool of CD4+ T cells.

Cytopathology or immunopathology? The puzzle of cytomegalovirus pneumonitis revisited

Various hypotheses have been proposed to explain why cytomegalovirus pneumonitis (CMV-P) is frequent and severe in bone marrow transplant patients while remaining rare and mild in HIV infected patients. One hypothesis suggests that CMV-P is an immunopathological condition that is common in bone marrow transplantation (BMT) under the effects of an abnormally regenerating immune system that reacts against CMV infected lung tissue. Such a hypothesis implicates CD4 T lymphocytes as one of the critical cell populations involved in immunopathology and also suggests that this process would be aborted by CD4 T cell deficiency in HIV infection. However, studies correlating the onset of CMV-P with lymphocyte reconstitution following BMT have revealed that CD4 cells are present at very low frequencies in the blood during the early period after transplantation when most cases of CMV-P occur. Furthermore, studies directly investigating bronchoalveolar lavage cell types during episodes of CMV-P in BMT patients have also failed to demonstrate significant CD4 involvement and, instead, have emphasized a predominance of natural killer (NK) cells and CD8 cells. These findings serve as the basis for questioning the validity of a CD4-driven immunopathological model of CMV-P in BMT. On the other hand, a variety of experimental and clinical observations support the protective role of CMV-specific CD3+ CD8 T lymphocytes against CMV in both immunocompetent individuals and BMT patients. In a murine BMT model, adoptive transfer of syngeneic BM cells was associated with massive increases in lung CD8 cells which resulted in the resolution rather than the exacerbation of existing CMV-P. In the light of these findings a more plausible hypothesis for CMV-P in BMT is that during the early period after transplantation adequate protective CD8 responses are absent and an uncontrolled CMV proliferation is allowed to develop. Once a critical viral load is reached a cytokine 'storm' may be triggered in the lung tissue that aggravates direct CMV-associated cytopathic effects. Likely candidates for this process would include the release of tumour necrosis factor-alpha (TNF-alpha) from alveolar macrophages stimulated by interferon-gamma (IFN-gamma) released from NK cells that are reconstituted early after BMT.

Immunologic and virologic responses to HAART in severely immunocompromised HIV-1-infected children

OBJECTIVE

To determine the long-term immunologic and virologic effects of highly active antiretroviral therapy (HAART) in children with AIDS.

DESIGN

A prospective observational study.

SETTING

Two pediatric HIV clinics.

PARTICIPANTS

Twenty-five protease-inhibitor naive HIV-infected children (aged 2-18 years) with advanced disease (CD4 < or =6%).

INTERVENTION

HAART (one protease inhibitor and one or more nucleoside analogs). Diphtheria and tetanus immunization in six patients after 18 months of therapy.

MAIN OUTCOME MEASURES

Changes in percentage of CD4 cells and plasma HIV-1 RNA levels; post-treatment assays of lymphoproliferative responses to recall antigens; CD4 cell memory phenotype.

RESULTS

Median duration of follow-up was 18.8 months (range, 7.5-28 months). At baseline the CD4 cell percentage was 2% (range, 0-6%), this increased significantly to 16% (range, 3-48%) above baseline at 12 months (P = 0.002). The mean maximum CD4 cell increase was 20.7% (range 4-48%) which corresponds to 657x10(6) cells/l (range, 30-2240x10(6) cells/l) above baseline. By contrast, the median viral load was not significantly lower at 12 months than at baseline (P = 0.34), and only 25% of the patients had sustained undetectable viral load. Of the reconstituted CD4 cells 70% were naive, and none of the subjects had lymphoproliferative responses to tetanus and diphtheria although 40% did develop responses to Candida, an environmental antigen. A single immunization with diphtheria and tetanus toxoid produced lymphoproliferative responses to tetanus in three out of six patients.

CONCLUSIONS

HAART was associated with sustained increases in CD4 cell counts, despite a high incidence of 'virologic failure'. CD4 counts and the proportion of naive cells were higher than have been reported in adults, which may be a reflection of greater thymic activity in children. Memory cell clones for antigens encountered in the past which are not prevalent before therapy could not be expanded without additional antigenic exposure.

In vivo and in vitro comparison of the short-term hematopoietic toxicity between hydroxyurea and trimidox or didox, novel ribonucleotide reductase inhibitors with potential anti-HIV-1 activity

Inhibitors of the cellular enzyme ribonucleotide reductase (hydroxyurea, [HU]) have been proposed as a new therapeutic strategy for the treatment of HIV type-1 (HIV-1) infection. However, HU use may be limited by the frequent development of hematopoietic toxicity. We report here short-term hematopoietic toxicity in mice receiving HU when compared to either of two more potent enzyme inhibitors, didox (DX) and trimidox (TX). High dose HU, DX, and TX monotherapy (500, 460, and 220 mg/kg/day respectively) was administered by daily i.p. injection (Monday-Friday) to C57BL/6 mice for 10 weeks. Effects on hematopoiesis were established by quantitating peripheral blood indices (hematocrit, hemoglobin, mean corpuscular volume, mean cell hemoglobin, mean corpuscular hemoglobin concentration, RBC, and WBC) and numbers of colony-forming units-granulocyte-macrophage (CFU-GM) and BFU-E from bone marrow and spleen. HU produced rapid induction of a macrocytic hypochromic anemia and altered white blood cell kinetics associated with myelosuppression defined as reduced marrow organ cellularity and induction of splenic extramedullary hematopoiesis. Compared to HU, TX and DX induced fewer changes in peripheral blood indices and CFU-GM and BFU-E per hematopoietic organ. In vitro human and murine marrow CFU-GM and BFU-E colony formations were assayed in the presence of dose escalation HU, DX, or TX (0, 1, 10, 50, 100, and 200 microM). HU inhibited colony formation more than either DX or TX. These in vivo and in vitro studies suggest that novel ribonucleotide reductase inhibitors TX and DX may provide an effective alternative to HU in HIV-1 therapy because they demonstrate reduced hematopoietic toxicity.

Antigen-driven CD4+ T cell and HIV-1 dynamics: residual viral replication under highly active antiretroviral therapy

Antigen-induced stimulation of the immune system can generate heterogeneity in CD4+ T cell division rates capable of explaining the temporal patterns seen in the decay of HIV-1 plasma RNA levels during highly active antiretroviral therapy. Posttreatment increases in peripheral CD4+ T cell counts are consistent with a mathematical model in which host cell redistribution between lymph nodes and peripheral blood is a function of viral burden. Model fits to patient data suggest that, although therapy reduces HIV replication below replacement levels, substantial residual replication continues. This residual replication has important consequences for long-term therapy and the evolution of drug resistance and represents a challenge for future treatment strategies.

HIV-1 and T cell dynamics after interruption of highly active antiretroviral therapy (HAART) in patients with a history of sustained viral suppression

Identifying the immunologic and virologic consequences of discontinuing antiretroviral therapy in HIV-infected patients is of major importance in developing long-term treatment strategies for patients with HIV-1 infection. We designed a trial to characterize these parameters after interruption of highly active antiretroviral therapy (HAART) in patients who had maintained prolonged viral suppression on antiretroviral drugs. Eighteen patients with CD4(+) T cell counts >/= 350 cells/microliter and viral load below the limits of detection for >/=1 year while on HAART were enrolled prospectively in a trial in which HAART was discontinued. Twelve of these patients had received prior IL-2 therapy and had low frequencies of resting, latently infected CD4 cells. Viral load relapse to >50 copies/ml occurred in all 18 patients independent of prior IL-2 treatment, beginning most commonly during weeks 2-3 after cessation of HAART. The mean relapse rate constant was 0.45 (0.20 log(10) copies) day(-1), which was very similar to the mean viral clearance rate constant after drug resumption of 0.35 (0.15 log(10) copies) day(-1) (P = 0.28). One patient experienced a relapse delay to week 7. All patients except one experienced a relapse burden to >5,000 RNA copies/ml. Ex vivo labeling with BrdUrd showed that CD4 and CD8 cell turnover increased after withdrawal of HAART and correlated with viral load whereas lymphocyte turnover decreased after reinitiation of drug treatment. Virologic relapse occurs rapidly in patients who discontinue suppressive drug therapy, even in patients with a markedly diminished pool of resting, latently infected CD4(+) T cells.

Intravenous drug use, relationship with providers, and stage of HIV disease influence the prescription rates of protease inhibitors

OBJECTIVE

To assess rates of prescriptions of protease inhibitors (PI) and determinants of not being prescribed PIs in a cohort of HIV-infected people eligible (according to published guidelines) for highly active antiretroviral therapy (HAART).

DESIGN

Cross-sectional survey.

METHODS

A total of 684 patients with CD4+ counts <500 cells/microl were enrolled from seven Italian HIV treatment centers from October 1997 to April 1998. A questionnaire on health-related quality of life (MOS-HIV) and patient ratings of the quality of care was administered. Sociodemographic variables, HIV disease-related factors, and prescribed antiretroviral therapy were also recorded.

RESULTS

61% of those enrolled were prescribed PI (median, 7.5 months). In addition, 75% of patients had previously received antiretroviral therapy. Fewer than 1% were prescribed nonnucleoside reverse transcriptase inhibitors (NNRTIs). Using multivariable logistic regression considering those with CD4+ counts <500 cells/microl, patients reporting the least information received (odds ratio [OR], 1.78; 95% confidence interval [CI], 1.23-2.58), injecting drug users (IDUs; OR, 1.73; 95% CI, 1.18-2.54), people with CD4+ counts >200 cells/microl (OR, 1.76; 95% CI, 1.19-2.61), and patients with early stage disease (OR, 2.24; 95% CI, 1.73-2.90) were less likely to have be prescribed PIs.

CONCLUSIONS

Of patients eligible for HAART, only 61% were prescribed PIs. People who wanted more information, IDUs, and patients in earlier disease stages are significantly less likely to be prescribed PIs. Access to HAART remains a critical issue in the management of HIV disease.

HIV-1 genotypic resistance patterns predict response to saquinavir-ritonavir therapy in patients in whom previous protease inhibitor therapy had failed

BACKGROUND

Tests for resistance to HIV drugs are available for clinical use; however, their predictive value has not been fully assessed.

OBJECTIVES

To determine HIV-1 genotypic predictors of a virologic response to saquinavir-ritonavir therapy in patients in whom at least one previous protease inhibitor-containing regimen had failed and to compare the predictive value of baseline genotype with that of standard clinical evaluation.

DESIGN

Retrospective clinical cohort study.

SETTING

University-based HIV clinic.

PATIENTS

54 HIV-1-infected adults treated with saquinavir-ritonavir who had experienced virologic failure while receiving a protease inhibitor-containing regimen for at least 3 months.

MEASUREMENTS

HIV-1 reverse transcriptase and protease gene sequences, CD4 cell counts, clinical characteristics, detailed antiretroviral treatment history, and plasma HIV-1 RNA levels at baseline and at three follow-up time points (median, 4, 12, and 26 weeks). Virologic failure was defined as a plasma HIV RNA level greater than 1000 copies/mL.

RESULTS

In 22 patients (41%), a plasma HIV-1 RNA level less than 500 copies/mL was achieved by week 12; in 15 patients (28%), this response was maintained through week 26. Clinical characteristics predicting a poorer response included a diagnosis of AIDS, lower CD4 cell count, and higher plasma HIV RNA level (P<0.03). Number of previous nucleoside reverse transcriptase inhibitors, previous protease inhibitor therapy, and duration of previous protease inhibitor therapy were predictors of poorer response (P<0.01). Multivariate regression models revealed that protease mutations present at the initiation of saquinavir-ritonavir therapy were the strongest predictors of virologic response. A model of clinical features explained up to 45% of the variation in virologic outcomes by week 12, whereas the explained variance was 71% when genotypic predictors were included.

CONCLUSIONS

In patients in whom protease inhibitor-containing antiretroviral therapy fails, HIV-1 genotype is predictive of virologic response to subsequent therapy. This predictive capacity adds to that of standard clinical evaluation.

Activation of CD8 T cells normalizes and correlates with the level of infectious provirus in tonsils during highly active antiretroviral therapy in early HIV-1 infection

OBJECTIVES

To study the effects of antiretroviral therapy on T cell activation in blood and tonsils from HIV-1 infected individuals in relation to CD4 cell count, plasma viremia, and infectious HIV-1 provirus.

DESIGN

A 48-week study of viral load and T cell subsets in blood and tonsils from 12 HIV-1-positive individuals with a mean CD4 cell number of 400 x 10(6) cells/l treated with a combination of zidovudine, lamivudine, and indinavir.

METHODS

Tonsil biopsies and blood samples were collected at regular intervals. Lymphocytes were phenotyped and quantified by three-color flow cytometry; infectious provirus was quantified by a limiting dilution assay. HIV-1-negative individuals were included as controls.

RESULTS

The fraction of tonsillar CD8 T cells expressing CD69, CD38, or HLA-DR in the patients with suppressed virus replication declined to levels comparable with that in controls by 48 weeks and showed a strong positive correlation with tonsillar infectious provirus and plasma viremia. The level of CD4 T cell activation was within normal range in tonsils throughout the study. The fraction of HLA-DR+ cells within CD4 and CD8 T cells in blood declined rapidly in parallel with plasma viremia but remained slightly higher compared with that in uninfected individuals.

CONCLUSION

Antiretroviral therapy normalizes tonsillar CD8 T cell activation in HIV-1-positive individuals in parallel with suppression of viral replication, indicating reduced CD8 cell turnover. Normal tonsillar CD4 T cell activation suggests limited CD4 cell turnover in early HIV infection. Activated CD8 T cells in lymphoid tissue is superior to that in blood as an immunological marker for the virological response to antiretroviral therapy.

A randomized study comparing triple versus double antiretroviral therapy or no treatment in HIV-1-infected patients in very early stage disease: the Spanish Earth-1 study

BACKGROUND

Most current guidelines state that antiretroviral therapy should be considered for HIV-infected patients with plasma HIV RNA > 5000-10000 copies/ml and CD4 cells > 500 x 10(6) cells/l. However, there is increasing concern about whether this is the optimal point to begin treatment or whether it is better to delay the initiation to more advanced stages.

OBJECTIVE

To study the immunological and virological benefits of starting antiretroviral therapy at these early stages.

METHODS

A total of 161 HIV-infected asymptomatic patients with CD4 cell count > 500 x 10(6) cells/l and viral load > 10000 copies/ml were randomly assigned to one of five treatment groups: no treatment, twice daily zidovudine and thrice daily zalcitabine (ZDV-ddC), twice daily zidovudine and didanosine (ZDV-ddI), twice daily stavudine and didanosine (D4T-ddI), or a twice daily three-drug regimen with stavudine and lamivudine and ritonavir. The endpoints were progression to < 350 x 10(6) cells/l CD4 cells, to < 500 x 10(6) cells/l with either two Centers for Disease Control class B symptoms or an increase of viral load > 0.5 log10 copies/ml above baseline, or to AIDS or death. In various substudies, the lymphoid tissue and cerebrospinal fluid viral load, development of genotypic resistance, proliferative responses to mitogens and cytomegalovirus, and HIV-1 specific antigens and other immunophenotypic markers were also analysed.

RESULTS

Progression rates to study endpoints within 1 year were greater in the control group (31%) than in all groups receiving antiretroviral therapy pooled together (5%; estimated hazard ratio 7.41; 95% confidence interval 5.72-74.55; P < 0.001). The peak mean viral load decrease was greater in the three-drug group when compared with any of the three groups with a two-drug regimen (2.32, 1.65, 1.72 and 1.84, respectively; P < or = 0.001). At 1 year, viral load remained below 20 copies/ml in 30 out of 33 patients in the three-drug group (91%) and in only eight out of 94 patients (9%) in two-drug groups (P = 0.001). The peak mean increase in CD4 cells was also greater in the three-drug group than in the double treatment arms (259 versus 85, 144 and 145 x 10(6) cells/l, respectively; P = 0.001). By comparison, 36% of patients in the three-drug group regimen had to change the therapy as a result of adverse events. Substudies were performed in 60 patients recruited at two sites. Tonsillar tissue HIV RNA was measured in seven patients (two in the two-drug groups and five in the three-drug group) in whom plasma HIV RNA was < 20 copies/ml at 1 year. It was 15151 and 133333 copies/mg tissue in the two patients from the two-drug group, < 40 copies/mg tissue in four patients in the three-drug group, and 485 copies/mg in one patient in the three-drug group. At 1 year there was a mean increase of 4.21+/-2.94% in CD8+CD38+ cells in the control group and a decrease of 9.48+/-3.36% in the two-drug groups (P = 0.01), and 19.87+/-3.64 in the three-drug group (P = 0.001 and P = 0.05, for comparisons with control group and two-drug groups, respectively). Although proliferative responses to cytomegalovirus antigens were significantly greater in those receiving antiretroviral therapy, response to HIV-1 p24 antigen was not detected in any patient in either treatment group.

CONCLUSIONS

This study supports the recommendation to start antiretroviral therapy with a three-drug combination during very early stages of HIV-1 disease, at least if viral load is above a cut-off point (10000 copies/ml in our study). The risk of progression was sevenfold higher in non-treated patients at 8 months of follow-up. Some immune system parameters improved toward normal values after 1 year of antiretroviral therapy, but the proliferative response of CD4 T lymphocytes against the p24 HIV-1 antigen was not recovered. Therapeutic approaches with more potent, better-tolerated and more convenient regimens will increasingly favour early intervention with antiretroviral t

Consistent viral evolutionary changes associated with the progression of human immunodeficiency virus type 1 infection

To understand the high variability of the asymptomatic interval between primary human immunodeficiency virus type 1 (HIV-1) infection and the development of AIDS, we studied the evolution of the C2-V5 region of the HIV-1 env gene and of T-cell subsets in nine men with a moderate or slow rate of disease progression. They were monitored from the time of seroconversion for a period of 6 to 12 years until the development of advanced disease in seven men. Based on the analysis of viral divergence from the founder strain, viral population diversity within sequential time points, and the outgrowth of viruses capable of utilizing the CXCR4 receptor (X4 viruses), the existence of three distinct phases within the asymptomatic interval is suggested: an early phase of variable duration during which linear increases ( approximately 1% per year) in both divergence and diversity were observed; an intermediate phase lasting an average of 1.8 years, characterized by a continued increase in divergence but with stabilization or decline in diversity; and a late phase characterized by a slowdown or stabilization of divergence and continued stability or decline in diversity. X4 variants emerged around the time of the early- to intermediate-phase transition and then achieved peak representation and began a decline around the transition between the intermediate and late phases. The late-phase transition was also associated with failure of T-cell homeostasis (defined by a downward inflection in CD3(+) T cells) and decline of CD4(+) T cells to Collapse

Key Words Collapse

MESH Headings

• Base Sequence
• DNA, Viral
• Disease Progression
• Evolution, Molecular
• Gene Products, env/genetics
• HIV Infections/immunology
• HIV Infections/physiopathology
• HIV Infections/virology
• HIV-1/classification
• HIV-1/genetics
• Humans
• Male
• Molecular Sequence Data
• Prospective Studies

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Grants

• U01 AI035042 NIAID NIH HHS
• AI34783 NIAID NIH HHS
• U01 AI037984 NIAID NIH HHS
• AI37984 NIAID NIH HHS
• U01 AI035041 NIAID NIH HHS
• P30 AI027757 NIAID NIH HHS
• AI32885 NIAID NIH HHS
• U01 AI035040 NIAID NIH HHS
• U01 AI035039 NIAID NIH HHS

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Affiliation(s)

R Shankarappa Department of Microbiology, University of Washington School of Medicine, Seattle, Washington 98195-7740, USA
J B Margolick
S J Gange
A G Rodrigo
D Upchurch
H Farzadegan
P Gupta
C R Rinaldo
G H Learn
X He
X L Huang
J I Mullins

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Collaborators Collapse

Clinical and immuno-virologic characterization of the efficacy of stavudine, lamivudine, and indinavir in human immunodeficiency virus infection

Clinical, virologic, and immunologic outcomes were analyzed in children with vertically transmitted human immunodeficiency virus (HIV) infection (n = 25) and clinical symptoms and evidence of immunosuppression to establish the efficacy of 18 months' treatment with stavudine, lamivudine, and indinavir. Children were naive for treatment with protease inhibitors and lamivudine and had minimal exposure to stavudine. At 1, 6, 12, and 18 months, the proportions of patients with HIV-RNA <400 copies/mL were 79%, 100%, 94%, 87% in Centers for Disease Control and Prevention (CDC) immunologic class 2 and 50%, 67%, 67%, 72% in CDC immunologic class 3. At 12 months, the median CD4(+) count and percent increased significantly in both CDC immunologic class groups, but to a greater extent in the class 3 group. In the 12- to 18-month period, there were no significant changes within the groups. In both groups there was a steady increase in the proportion and number of children with positive skin test responses. Children in class 2 were more likely to have a positive delayed-type hypersensitivity response and a greater number of positive responses. Lymphocyte proliferative response to recall antigens improved significantly in all patients. The rate of increase in positive test results was faster in children in class 2 than in those in class 3. Only minor clinical events occurred during 18 months of therapy. Potent antiretroviral therapy achieves a sustained benefit in HIV-infected children, but immune reconstitution is more likely achieved in children with less advanced disease.

CMV retinitis in the era of HAART

Since 1996, major advances in the treatment of AIDS have markedly changed the incidence and the prognosis of CMV retinitis. Highly active antiretroviral therapy (HAART) is a combination of nucleoside reverse transcriptase inhibitors and protease inhibitors. This new therapeutic strategy is highly efficient in reducing the HIV viral load and increasing CD(4)+ T-lymphocyte count. These biological effects are associated with an improvement of immune functions. Clinically, the completely quiescent CMV retinitis and the unusual prolonged relapse-free interval suggest a certain restoration of immune functions, making possible the discontinuation of maintenance therapy. For most authors, the decision to stop anti-CMV maintenance therapy is based on a CD4+ cell count >100 cells/microl with a low HIV viral load for at least four months. The improvement of CMV retinitis on HAART may also be associated with an intraocular inflammation called immune recovery vitritis. For some patients, this vitritis may be associated cystoid macular edema and an epiretinal membrane responsible for visual loss.

Clinical and immunologic response without decrease in virus load in patients with AIDS after 24 months of highly active antiretroviral therapy

This study reports an analysis of clinical, virological, and immunologic outcomes in a cohort of 77 multidrug-experienced AIDS patients during 24 months of highly active antiretroviral therapy (HAART). Our results have shown a reduced risk of AIDS complications, prolonged survival, and immunologic benefit even in the absence of sustained virus suppression. The degree of immunodepression, the risk factors for HIV-1 infection, the use of 2 drugs instead of 3, and a change in protease inhibitor were independently correlated with virological failure. In the majority of studied patients, an increase in CD4+ T cells was observed after HAART. However, the increase was more pronounced in patients who showed a decrease in virus load than in those who did not. Moreover, we observed an absence of relapses among patients who permanently discontinued prophylaxis for Cytomegalovirus retinitis and atypical mycobacterial infections. Peripheral lipodystrophy developed in the majority of patients, regardless of treatment used and virological outcome.

Regression of AIDS-related Kaposi's sarcoma following antiretroviral therapy with protease inhibitors: biological correlates of clinical outcome

The clinical response of AIDS-related Kaposi's sarcoma (KS) to highly active antiretroviral therapy (HAART), a combination of human immunodeficiency virus type 1 (HIV-1) protease and reverse transcriptase inhibitors, was studied in 11 patients, all but one with progressive KS. CD4+ cell counts, plasma HIV-1 RNA levels, and antibody titres to lytic ORF65 and latency-associated human herpes virus type 8 (HHV-8) proteins were determined in sequential samples. Six complete and three partial clinical responses were achieved in a median time of 6 and 3 months, respectively, and confirmed after a median time of 16 months on HAART. 2 patients showed disease progression. A consistent decrease in HIV-1 RNA levels, paralleled by an increase in CD4+ cell counts, was observed in all patients who showed complete or partial clinical response; HIV-1 RNA levels remained persistently high in the two patients who progressed, despite a change in HAART. HHV-8 antibody titres were generally higher in patients with mucosal/visceral involvement compared with patients with limited disease; a decrease in ORF65 antibody titre was significantly associated with a clinical response. These results indicate that HAART is effective for AIDS-related KS; the clinical response correlates with a decrease in plasma HIV-1 RNA levels, an increase in CD4+ lymphocytes, and a decrease in antibodies to ORF65 HHV-8 protein.

Effects of the human CD38 glycoprotein on the early stages of the HIV-1 replication cycle

CD38 displays lateral association with the HIV-1 receptor CD4. This association is potentiated by the HIV-1 envelope glycoprotein gp120. The aim of this work was to evaluate the CD38 role in T cell susceptibility to HIV-1 infection. Using laboratory X4 HIV-1 strains and X4 and X4/R5 primary isolates, we found that CD38 expression was negatively correlated to cell susceptibility to infection, evaluated as percentage of infected cells, release of HIV p24 in the supernatants, and cytopathogenicity. This correlation was at first suggested by results obtained in a panel of human CD4(+) T cell lines expressing different CD38 levels (MT-4, MT-2, C8166, CEMx174, Supt-1, and H9) and then demonstrated using CD38 transfectants of MT-4 cells (the line with the lowest CD38 expression). To address whether CD38 affected viral binding, we used mouse T cells that are non-permissive for productive infection. Gene transfection in mouse SR.D10.CD4(-).F1 T cells produced four lines expressing human CD4 and/or CD38. Ability of CD4(+)CD38(+)cells to bind HIV-1 or purified recombinant gp120 was significantly lower than that of CD4(+)CD38(-) cells. These data suggest that CD38 expression inhibits lymphocyte susceptibility to HIV infection, probably by inhibiting gp120/CD4-dependent viral binding to target cells.-Savarino, A., Bottarel, F., Calosso, L., Feito, M. J., Bensi, T., Bragardo, M., Rojo, J. M., Pugliese, A., Abbate, I., Capobianchi, M. R., Dianzani, F., Malavasi, F., and Dianzani, U. Effects of the human CD38 glycoprotein on the early stages of theHIV-1 replication cycle.

Epidemiological considerations about retinal opportunistic infections in HIV-infected patients in France

PURPOSE

To evaluate the evolution of the epidemiology of retinal opportunistic infections in HIV-infected patients from 1994 to 1997 and to assess the effect of HAART initiated in 1996.

MATERIALS AND METHODS

Epidemiological prospective study using the data collected during ocular examinations of HIV-infected patients conducted in a single referral center specialized in HIV infection.

RESULTS

From 1995 to 1997, the total number of examined HIV-infected patients and the incidence of retinitis related to CMV, VZV, tuberculosis, and toxoplasmosis decreased. The incidence of CMV retinitis, which was by far the most frequent ocular infection, fell from 6.2% to 1.2%.

COMMENTS

The dramatic decrease in retinal opportunistic infections since 1996 may be related to the use of HAART. However, a close follow-up is still justified due to the increasing occurrence of resistance to protease inhibitors.

Transfer of human CD4(+) T lymphocytes producing beta interferon in Hu-PBL-SCID mice controls human immunodeficiency virus infection

Beta interferon (IFN-beta) exerts pleiotropic antiretroviral activities and affects many different stages of the human immunodeficiency virus (HIV) infectious cycle in IFN-treated cells. To explore whether transfer of genetically engineered human CD4(+) T cells producing constitutively low amounts of IFN-beta can eradicate HIV in vivo, we developed a new Hu-PBL-SCID mouse model supporting a persistent, replicative HIV infection maintained by periodic reinoculations of activated human CD4(+) T cells. Transferring human CD4(+) T cells containing the IFN-beta retroviral vector drastically reduced the preexisting HIV infection and enhanced CD4(+) T-cell survival and Th1 cytokine expression. Furthermore, in 40% of the Hu-PBL-SCID mice engrafted with IFN-beta-transduced CD4(+) T cells, HIV-1 was undetectable in vivo as well as after cocultivation of mouse tissues with human phytohemagglutinin-stimulated lymphoblasts. These results indicate that a therapeutic strategy based upon IFN-beta transduction of CD4(+) T cells may be an approach to controlling a preexisting HIV infection and allowing immune restoration.

Effect of long-term infection with nef-defective attenuated HIV type 1 on CD4+ and CD8+ T lymphocytes: increased CD45RO+CD4+ T lymphocytes and limited activation of CD8+ T lymphocytes

Members of the Sydney Blood Bank Cohort (SBBC) have been infected with an attenuated strain of HIV-1 with a natural nef/LTR mutation and have maintained relatively stable CD4+ T lymphocyte counts for 14-18 years. Flow cytometric analysis was used to examine the phenotype of CD4+ and CD8+ T lymphocytes in these subjects, including the immunologically important naive (CD45RA+CD62L+), primed (CD45RO+), and activated (CD38+HLA-DR+ and CD28-) subsets. The median values were compared between the SBBC and control groups, comprising age-, sex-, and transfusion-matched HIV-1-uninfected subjects; transfusion-acquired HIV-1-positive LTNPs; and sexually acquired HIV-1-positive LTNPs. Members of the SBBC not only had normal levels of naive CD4+ and CD8+ T lymphocytes, but had primed CD45RO+ CD4+ T lymphocytes at or above normal levels. Furthermore, these primed cells expressed markers suggesting recent exposure to specific antigen. SBBC members exhibited variable activation of CD8+ T lymphocytes. In particular, SBBC members with undetectable plasma HIV-1 RNA had normal levels of activated CD8+ T lymphocytes. Therefore, the result of long-term infection with natural nef/LTR mutant HIV-1 in these subjects suggests a decreased cytopathic effect of attenuated HIV-1 on susceptible activated CD4+ T lymphocyte subsets in vivo, and minimal activation of CD8+ T lymphocytes.

Assessment of type 1 and type 2 cytokines in HIV type 1-infected individuals: impact of highly active antiretroviral therapy

Although the effect of highly active antiretroviral therapy (HAART) on HIV-1 replication has been established, the mechanisms involved in restoration of immune responses and reconstitution remain unknown. This study provides evidence of changes in expression of type 1 and type 2 cytokine-specific mRNA occurring during HIV-1 infection, before and after initiation of HAART. Unstimulated PBMCs from nine HIV-1-infected individuals obtained at different time intervals before and after the initiation of HAART were assessed for specific IFN-gamma, IL-2, IL-4, and IL-10 mRNA expression, using RT-PCR. Correlation with CD4+ T cell counts and viral load was also carried out. Before initiation of HAART, in all patients, little expression of specific IFN-gamma and IL-2 (type 1 cytokine) mRNA was noted. In contrast, expression of specific IL-4 and/or IL-10 (type 2) mRNA was readily detectable in the majority of patients. After initiation of HAART there was a continuous increase in IFN-gamma and IL-2 mRNA expression, although the latter occurred in lower amounts. This paralleled a dramatic reduction in viral load and increase in CD4+ T cell counts. Type 2 cytokine-specific mRNA expression fell to undetectable levels and in some cases reappeared later in the course of HAART. Predominant expression of type 2 cytokine mRNA, before initiation of HAART, concurs with previous findings of a dominant antiproliferative, type 2 cytokine profile during HIV-1 infection. Reversion of the cytokine profile, after HAART, to a strong type 1 profile suggests that in addition to suppressing virus replication directly the immune system may be given a chance to recover.

Primary isolate neutralization by HIV type 1-infected patient sera in the era of highly active antiretroviral therapy

Sera from highly selected HIV-1-positive patients are known to have the ability to neutralize a diverse array of primary isolates of HIV-1. The human osteosarcoma cell line that expresses CD4 and chemokine receptors (GHOST cells) was adapted to study HIV-1 neutralization in 37 HIV-1-infected individuals who were selected because of slow disease progression or nonprogression. Many of these individuals were receiving combination drug therapy. Molecularly cloned HIV-1 JR-FL and NL4-3 viruses were used as prototypes to define assay conditions. Sera were then tested at a 1:40 dilution against six additional primary isolates, three of which utilized CCR5 and three of which used both CCR5 and CXCR4. The assay was highly reproducible and independent of viral input titer, with a readout at 48 hr equivalent to that at later time points. As previously reported, neutralization sensitivity was entirely independent of coreceptor usage. Only a few sera from slow progressors were able to neutralize a broad array of primary isolates at a 1:40 dilution, and the best clinical predictor of broadly neutralizing antibody for primary isolates was the present use of antiretroviral agents. In further studies it was found that purified antibody accounted for the majority of the measured neutralization. However, experiments with exogenous addition of antiviral agents showed that the use of nucleosides also greatly contributed to the measured neutralization in some patients. Measurement of neutralization of HIV-1 primary isolates by sera from patients receiving antiretroviral therapy must be carried out with some caution.

Activation-induced CD4+ T cell death in HIV-positive individuals correlates with Fas susceptibility, CD4+ T cell count, and HIV plasma viral copy number

The relevance of activation-induced cell death (AICD) of CD4+ T cells to AIDS pathogenesis is unknown. The present study investigates the relationship of AICD to a defined molecular mechanism regulating peripheral T cell homeostasis, Fas-mediated apoptosis, and clinical correlates of the pathogenesis of AIDS. Increased pokeweed mitogen (PWM)-induced AICD (22.8 versus 4.4%, p = 0.006) and Fas-mediated apoptosis (27.7 versus 12.0%, p = 0.002) of CD4+ T cells were observed in HIV+ versus HIV- individuals. Similarly, increased PWM-mediated AICD (16.2 versus 2.2%, p < 0.001) and Fas-mediated apoptosis (25.8 versus 7.6%, p = 0.005) were noted in CD8+ T cells from HIV+ versus HIV- individuals. PWM-induced AICD of CD4+ T cells was blocked (83% median specific inhibition) by Fas-blocking antibodies, whereas PWM-induced AICD of CD8+ T cells was Fas independent. Comparison between PWM- and anti-CD3-mediated AICD of CD4+ T cells indicated that PWM- and not CD3-induced AICD is Fas dependent. HIV+ individuals with an HIV RNA copy number of <30,000 copies/ml had lower PWM-induced AICD of CD4+ T cells than did those with an HIV RNA copy number of >30,000 copies/ml (5.7 versus 22.1%, p = 0.034), and PWM-induced AICD inversely correlated with CD4+ T cell count (R = -0.567, p = 0.043). Initiation of HAART decreased PWM-induced CD4+ T cell AICD from 24.4 to 9.4% posttreatment (p = 0.035). These results demonstrate that PWM-induced AICD of CD4+ T cells from HIV+ individuals is mediated by Fas/FasL, parallels the in vivo susceptibility of the CD4+ T cell to Fas-mediated apoptosis, and correlates with clinical markers of AIDS pathogenesis and response to HAART.

Sexual transmission and propagation of SIV and HIV in resting and activated CD4+ T cells

In sexual transmission of simian immunodeficiency virus, and early and later stages of human immunodeficiency virus-type 1 (HIV-1) infection, both viruses were found to replicate predominantly in CD4(+) T cells at the portal of entry and in lymphoid tissues. Infection was propagated not only in activated and proliferating T cells but also, surprisingly, in resting T cells. The infected proliferating cells correspond to the short-lived population that produces the bulk of HIV-1. Most of the HIV-1-infected resting T cells persisted after antiretroviral therapy. Latently and chronically infected cells that may be derived from this population pose challenges to eradicating infection and developing an effective vaccine.

Synthesis and anti-HIV activity of arylpiperazinyl fluoroquinolones: a new class of anti-HIV agents

Synthesis and anti-HIV activity of a series of novel arylpiperazinyl fluoroquinolones are reported. In the SAR study, the aryl substituents on the piperazine nitrogen were found to play an important role for the anti-HIV-1 activity. A few of the compounds exhibited potent anti-HIV activity: IC50=0.06 microM in chronically infected cells.

Dual role of TNF-alpha in NK/LAK cell-mediated lysis of chronically HIV-infected U1 cells. Concomitant enhancement of HIV expression and sensitization of cell-mediated lysis

The U937-derived chronically HIV-infected U1 cell line and uninfected U937 cell clones were efficiently lysed by both unstimulated (NK) and IL-2-stimulated (lymphokine-activated killer; LAK) peripheral blood mononuclear cells (PBMC) of healthy HIV-seronegative donors. Pretreatment of target cells with IFN-gamma down-modulated killing of both U1 cells and two U937 cell clones, and up-regulated MHC class I expression. In contrast, TNF-alpha enhanced the sensitivity of infected U1 cells, but not of U937 cell clones to NK / LAK cell lysis. Co-cultivation of IL-2-stimulated PBMC with U1 cells triggered expression and replication of HIV by cell-cell contact, and this effect was inhibited by anti-TNF-alpha antibodies (Ab); virus production was partially inhibited by zidovudine. Of interest, anti-TNF-alpha Ab protected U1 cells from LAK cell activity. Thus, TNF-alpha can induce HIV expression from chronically infected U1 cells, but also plays an important role in sensitizing these cells to lysis.

Kinetics of antiviral activity and intracellular pharmacokinetics of human immunodeficiency virus type 1 protease inhibitors in tissue culture

We have examined the kinetics of the inhibition of human immunodeficiency virus type 1 (HIV-1) particle infectivity by protease inhibitors (PIs) in cell culture, using either transfected HeLa cells or infected peripheral blood mononuclear cells (PBMCs) as producers of infectious virions. Both the kinetics of the initiation of antiviral activity after addition of the PIs to these cultures and the kinetics of restoration of virion infectivity after removal of the PIs from the treated cultures were examined. We found that the kinetics of initiation of particle infectivity inhibition produced by a high extracellular concentration (5 microM) of the inhibitors were similar for all five inhibitors tested: loss of particle infectivity was perceptible as early as 1 h after the initiation of PI treatment and increased gradually thereafter. By contrast, the durability of this antiviral effect following removal of the drug from the culture varied dramatically according to the drug studied. In transfected HeLa cells, saquinavir and nelfinavir exerted the most prolonged inhibition, with the half-lives of their antiviral activities being greater than 24 h, while ritonavir exerted an intermediate length of inhibition (18 h) and indinavir and amprenavir exerted a reproducibly shorter length of inhibition (5 h). For all five tested PIs, these kinetics were significantly faster in PBMCs than in HeLa cells. The striking differences in antiviral kinetics observed among the different PIs appear mostly due to differences in their intracellular concentrations and/or rates of cellular clearance. Our observations, although limited to tissue culture conditions, may help delineate the cellular parameters of the antiviral activities of HIV-1 PIs and further optimize the efficiencies of these antiretrovirals in vivo.

Cytomegalovirus retinitis in advanced HIV-infected patients treated with protease inhibitors: incidence and outcome over 2 years

We prospectively studied the incidence of cytomegalovirus (CMV) retinitis in 93 patients treated with highly active antiretroviral therapy (HAART) containing a protease inhibitor (PI), during a median follow-up period of 24 months. The median initial CD4+ count was 22 cells/microl (range, 1-311 cells/microl), and the median plasma HIV viral load was 5.1 log10 copies/ml (range, 2.4-6.4 log10 copies/ml). The fundus was examined monthly in patients with a history of CMV retinitis or an initial CD4+ count <50 cells/microl and every 3 months in the other patients. Of patients with previously controlled CMV retinitis, 1 of 7 relapsed. In addition, 6 of 59 patients with a CD4+ count <50 cells/microl and no history of CMV retinitis before starting PI therapy developed CMV retinitis. Of them, 3 had at least one relapse during follow-up. CD4+ counts were <40 cells/microl at the time of primary or recurrent CMV retinitis, except in two cases (147 cells/microl and 203 cells/microl). In conclusion, the incidence of CMV retinitis was 0.091 per patient-year among study subjects with advanced HIV infection who were receiving HAART (95% confidence interval [CI], 0.037-0.145). The time to progression of CMV retinitis (mean, 215 days; 95% CI, 113-317 days) was longer than reported before widespread use of PIs.

Strategies of antiretroviral therapy in adults

Recent progress in antiretroviral treatment has led to dramatic improvements in HIV-related morbidity and mortality. These improvements have been fostered by advances in our understanding of HIV-related pathogenesis, the use of plasma HIV RNA levels to monitor patients, and the availability of 13 licensed antiretroviral drugs. Numerous drug combinations, especially those containing three or more agents, can suppress plasma HIV RNA levels below the lower limit of detection in the majority of treated patients. Urologists should be familiar with the limitations of this therapeutic response: patient adherence, drug resistance, a residual burden of chronically infected cells which are refractory to treatment, an unknown impact on HIV in genital secretions, and potential transmissibility through sexual contact.

Highly active anti-retroviral therapy (HAART) prolongs time to treatment failure in Kaposi's sarcoma

OBJECTIVE

To evaluate the impact of highly active antiretroviral therapy (HAART) on Kaposi's sarcoma.

DESIGN

Retrospective study of patients who had received systemic or local treatment for AIDS-related Kaposi's sarcoma who subsequently commenced HAART.

METHODS

Case note review to determine time to treatment failure for Kaposi's sarcoma before and after starting HAART. Time to treatment failure was calculated from the end of last therapy to the start of the next new treatment for Kaposi's sarcoma.

RESULTS

The cohort contained 78 patients. Only 38% had good risk Kaposi's sarcoma (stage T0I0) at presentation. The median time to treatment failure before starting HAART was 0.5 years. Initial HAART therapy was three or more drugs including a protease inhibitor for 38 (49%), three or more drugs without a protease inhibitor for 27 (35%) and a two-drug protease combination for 13 (16%). The median follow-up after starting HAART was 12 months (range, 0.5-52 months) and anti-Kaposi's sarcoma treatment has been required for 24 (31%) patients. The median time to treatment failure for Kaposi's sarcoma from the start of HAART is 1.7 years. This is statistically longer than the time to treatment failure for the same cohort of patients before they started HAART (log rank chi2 = 16.5, P < 0.0001). The serum HIV RNA viral load (VL) at the time of Kaposi's sarcoma progression revealed virological failure of HAART (defined as VL > 5000 copies/ml) in 14 of 24 (58%) and good control (VL < 200 copies/ml) in five of 24 (21%).

CONCLUSION

HAART is associated with prolonged time to treatment failure in Kaposi's sarcoma. Progression of Kaposi's sarcoma while on HAART is not necessarily associated with virological failure as determined by rising viral RNA titre.

Analysis of HIV cross-resistance to protease inhibitors using a rapid single-cycle recombinant virus assay for patients failing on combination therapies

OBJECTIVE

To assess the patterns of HIV phenotypic cross-resistance to protease inhibitors (PI) in patients experiencing viral load rebound on combination therapy including a PI.

METHODS

Phenotypic analysis of sensitivity to indinavir, nelfinavir, saquinavir, ritonavir and amprenavir was carried out using a single-cycle recombinant virus assay. Viral protease was sequenced by automated dideoxynucleotide chain termination.

RESULTS

Of the 108 patients studied, 68 had received indinavir, 50 ritonavir, 25 saquinavir and eight nelfinavir. The majority (71%) had received only one PI. The incidence of cross-resistance between indinavir, nelfinavir, ritonavir and saquinavir was high (60-90%). Cross-resistance to amprenavir was less frequent (37-40%). However there was some correlation between levels of sensitivity to amprenavir and indinavir (r2 = 0.34; P < 0.01). Conversely, the correlation between levels of sensitivity to indinavir and saquinavir was poor (r2 = 0.25), particularly for patients who had not received saquinavir. The degree of cross-resistance correlated with the level of resistance and with the total number of mutations in the protease gene (P < 0.05, chi square test) but could not be significantly correlated to any one particular mutation or combination of mutations. Mutation 184V was significantly associated with cross-resistance to amprenavir, with no mutations at codon 50 observed, while mutations associated with cross-resistance to saquinavir differed according to the treatment received.

CONCLUSIONS

These results suggest that, although the total number of protease mutations correlates with the degree of cross-resistance, the specific mechanisms accounting for primary resistance and for cross-resistance may be different.

Hydroxyurea and didanosine long-term treatment prevents HIV breakthrough and normalizes immune parameters

Hydroxyurea and didanosine treatment suppressed HIV replication for more than 2 years, in the absence of viral breakthrough, in chronically infected patients. The profile of viral load reduction was unusual for a two-drug combination, since a continuous gradual decrease in viremia persisted despite residual viral replication. The increase in CD4+ T cell counts was not robust. However, unlike those of patients treated by other therapies, CD4+ T lymphocytes were functionally competent against HIV, mediating a vigorous HIV-specific helper T cell response in half of these patients. In addition, the percentages of naive CD4+ and CD8+ T lymphocytes were not different from those in uninfected individuals. These results demonstrate that prolonged antiretroviral therapy with a simple, well-tolerated combination of two affordable drugs can lead to sustained control of HIV, normalization of immune parameters, and specific anti-HIV immune response.

Induction of HIV-1-specific T cell responses by administration of cytokines in late-stage patients receiving highly active anti-retroviral therapy

Highly active anti-retroviral therapy (HAART) is associated with reduction in the morbidity and mortality of patients with advanced HIV-1 disease. The ability of such treatment to improve immune responses against HIV-1 and opportunistic pathogens is variable and limited. Addition of cytokine immunotherapy to this treatment may improve immune responses. IL-2 with or without granulocyte-macrophage colony-stimulating factor (GM-CSF) was administered to HIV-1+ individuals receiving HAART with undetectable viral loads, and CD4 counts < 100 cells/microl. In one patient presenting with Mycobacterium avium complex (MAC) infection, we evaluated the effect of cytokine immunotherapy on lymphocyte phenotype; plasma viral load; proliferative responses to mitogens, recall and HIV-1 antigens; cytokine production and message in response to non-specific and specific stimuli; and natural killer (NK) cell activity. Proliferation assays were performed in two similar patients. Before cytokine immunotherapy the predominant CD8+ population was mainly CD28-. No proliferation or IL-2 production was seen in response to mitogens, recall or HIV-1 antigens; and no HIV-1 peptide-specific interferon-gamma (IFN-gamma)-secreting cells were present. Low levels of IL-4 were detected in response to antigens to which patients had been exposed, associated with up-regulated expression of costimulatory molecules influenced by IL-4. Following IL-2 administration, loss of IL-4 was associated with increased NK cell activity and HIV-1 peptide-specific and non-specific IFN-gamma-producing cells. Proliferative responses associated with IL-2 production and responsiveness were only seen after subsequent concomitant administration of GM-CSF with IL-2. These changes mirrored clinical improvement. An imbalance of lymphocyte subsets may account for immune unresponsiveness when receiving HAART. Restoration of responses following immunotherapy suggests a shift towards a lymphocyte profile with anti-pathogen activity.

The potential importance of HIV-induction of lymphocyte homing to lymph nodes

The mechanism by which HIV causes depletion of CD4 lymphocytes remains unknown. Recent studies have demonstrated that HIV binding to resting CD4 lymphocytes causes them to home from the blood into lymph node, and during the homing process, they are induced into apoptosis only to secondary signals through the homing receptors. If this is the principal mechanism of CD4 cell depletion, it can explain many of the events known to occur in HIV-infected individual.

Reduction in T cell apoptosis in patients with HIV disease following antiretroviral therapy

Patients with HIV infection manifest increased T lymphocyte apoptosis. This study investigated the influence of antiretroviral therapy (ART) upon lymphocyte apoptosis in 23 HIV-infected adults naive to protease inhibitors. Patients were enrolled in a treatment trial consisting of Nelfinavir (NFV), d4T, or NFV + d4T for 24 weeks, followed by triple therapy (NFV + reverse transcriptase inhibitors) for an additional 24 weeks. Spontaneous T cell apoptosis in cultured PBMC decreased by 23.67 +/- 18.2% (P < 0.006) at 48 weeks and plasma HIV RNA decreased by 1.79 +/- 0.59 log(10) RNA copies/ml (P < 0.001). The absolute decrease and slope of T cell apoptosis correlated with plasma virus load and with activated CD8 T cells and was inversely correlated with CD4 T cells. We conclude that reduction in chronic antigenic stimulation and the absence of cellular signals elicited by viral products contribute to the rescue of T lymphocytes from apoptosis, which facilitates immunologic recovery in ART-treated patients.

Natural history of HIV infection in the era of combination antiretroviral therapy

BACKGROUND

The use of protease inhibitor-containing (PI) combination antiretroviral therapy has led to a reduction in the incidence of opportunistic illness and mortality (events) in HIV infection. We wished to quantify the changing incidence of these events in our clinical practice and delineate the relationship between CD4, HIV-1 RNA, and development of events in patients receiving PI combination therapy.

METHODS

We assessed HIV-infected patients with CD4 counts < or =500 cells x10(6)/l. We calculated the incidence of events from 1994 through 1998 and analyzed the association of temporal changes in event incidence and use of antiretroviral therapy. In patients on PI combination therapy, we determined the probability of achieving and maintaining an undetectable HIV-1 RNA response and determined the association of CD4, HIV-1 RNA, and developing an event.

RESULTS

The incidence of opportunistic illness declined from 23.7 events/100 person-years in 1994 to 14.0 events/100 person-years in 1998 (P<0.001). Mortality declined from 20.2 deaths/100 person-years in 1994 to 8.4 deaths/ 100 person-years in 1998 (P<0.001). Use of PI combination therapy was associated with a relative rate of opportunistic illness or death of 0.66 [95% confidence interval (CI), 0.51-0.85; P<0.001]. The relative incidence of each of 16 opportunistic illnesses was approximately the same in 1998 as in 1994 except for lymphoma, cervical cancer and wasting syndrome which do not appeared to have declined in incidence. Approximately 60% of patients who received PI therapy achieved an undetectable HIV-1 RNA, and 65% of these patients maintained durable suppression of HIV-1 RNA. Achieving an undetectable HIV-1 RNA was associated with a decreased risk of an event, and was the variable most strongly associated with an increase in CD4 level. By multivariate analysis, the concurrent CD4 level was most strongly associated with developing an event.

CONCLUSIONS

We observed a significant decline in the incidence of opportunistic illness and death from 1994 through 1998 associated with combination antiretroviral therapy. Patients who develop events while being treated with PI combination therapy were not likely to have achieved an undetectable HIV-1 RNA and are likely to have a low concurrent CD4 level.

CCR5 and CXCR4 chemokine receptor expression and beta-chemokine production during early T cell repopulation induced by highly active anti-retroviral therapy

Expression of chemokine receptors and beta-chemokine production by peripheral blood mononuclear cells (PBMC) were determined in HIV-1-infected individuals before and after highly active anti-retroviral therapy (HAART) and their relationship to viral load, T cell phenotype and the expression of immunological activation markers was examined. We found that the expression of CCR5 is up-regulated in HIV-1-infected individuals while CXCR4 appears down-regulated on both CD4 and CD8 T cells compared with normal controls. These alterations are associated with the high levels of viral load. In addition, a relationship was observed between the degree of immune activation and chemokine receptor expression on T cells. However, after 3 months of combined anti-retroviral regimen, expression of CXCR4 significantly increased while CCR5 decreased when compared with pretherapy determinations. This was seen in strict association with a dramatic decrease of viral load and an increase of both CD45RA+/CD62L+ (naive) and CD45RA-/CD62L+ or CD45RA+/CD62L- (memory) T cells accompanied by a significant decrease of the expression of immune activation markers such as HLA-DR and CD38. At enrolment, both spontaneous and lectin-induced RANTES, macrophage inflammatory protein-1alpha (MIP-1alpha) and MIP-1beta production by PBMC were higher in HIV-1-infected individuals compared with normal controls, although differences for MIP-1beta were not statistically significant. However, RANTES and MIP-1alpha production decreased during HAART at levels closer to that determined with normal controls, while MIP-1beta production was less consistently modified. These data indicate that the expression of chemokine receptors CCR5 and CXCR4 and the production of beta-chemokines are altered in HIV-infected individuals, and suggest that their early modifications during HAART reflect both the peripheral redistribution of naive/memory T cell compartments and the decrease in levels of T cell activation. Such modifications in the expression of host determinants of viral tropism and the production of anti-viral molecules may play a role in the emergence of virus variants when a failure of HAART occurs.