Disease progression and survival following specific AIDS-defining conditions: a retrospective cohort study of 2048 HIV-infected persons in London

HIV-Infected Patients as a Model of Aging

We appraised the relationship between the biological and the chronological age and estimated the rate of biological aging in HIV-infected patients. Two independent biomarkers, the relative telomere length and iron metabolism parameters, were analyzed in younger (<35) and older (>50) HIV-infected and uninfected patients (control group). In our control group, telomeres of younger patients were significantly longer than telomeres of older ones. However, in HIV-infected participants, the difference in the length of telomeres was lost. By combining the length of telomeres with serum iron, ferritin, and transferrin iron-binding capacity, a new formula for determination of the aging process was developed. The life expectancy of the healthy population was related to their biological age, and HIV-infected patients were biologically older. The effect of antiretroviral HIV drug therapies varied with respect to the biological aging process. IMPORTANCE This article is focused on the dynamics of human aging. Moreover, its interdisciplinary approach is applicable to various systems that are aging.

Impact of HIV Infection on the Clinical Presentation and Survival of Non-Hodgkin Lymphoma: A Prospective Observational Study From Botswana

PURPOSE

Botswana has a high prevalence of HIV infection. Currently, there are few data regarding the sociodemographic factors, clinical characteristics, and outcomes of non-Hodgkin lymphoma (NHL)-an AIDS-defining cancer-in the country.

PATIENTS AND METHODS

This study used a prospective cancer registry to identify patients with a new diagnosis of NHL reporting for specialty cancer care at three hospitals in Botswana between October 2010 and August 2016. Treatment patterns and clinical outcomes were analyzed.

RESULTS

One hundred four patients with a new diagnosis of NHL were enrolled in this study, 72% of whom had HIV infection. Compared with patients not infected with HIV, patients infected with HIV were younger (median age, 53.9 v 39.1 years; P = .001) and more likely to present with an aggressive subtype of NHL (65.5% v 84.0%; P = .008). All patients infected with HIV received combined antiretroviral therapy throughout the course of the study, and similar chemotherapeutic regimens were recommended for all patients, regardless of subtype or HIV status (six to eight cycles of cyclophosphamide, doxorubicin, vincristine, and prednisone; or cyclophosphamide, doxorubicin, vincristine, and prednisone plus rituximab). There was no difference in 1-year mortality among patients not infected with HIV and patients infected with HIV (unadjusted analysis, 52.9% v 37.1%; hazard ratio [HR], 0.73; P = .33; adjusted analysis, HR, 0.57; P = .14). However, when compared with a cohort of patients in the United States matched by subtype, stage, age, sex, and race, patients in Botswana fared worse (1-year mortality, 22.8% v 46.3%; HR, 1.89; P = .001).

CONCLUSION

Among patients with NHL reporting for specialty cancer care in Botswana, there is no association between HIV status and 1-year survival.

HIV Infection Is Associated with Shortened Telomere Length in Ugandans with Suspected Tuberculosis

Introduction

HIV infection is a risk factor for opportunistic pneumonias such as tuberculosis (TB) and for age-associated health complications. Short telomeres, markers of biological aging, are also associated with an increased risk of age-associated diseases and mortality. Our goals were to use a single cohort of HIV-infected and HIV-uninfected individuals hospitalized with pneumonia to assess whether shortened telomere length was associated with HIV infection, TB diagnosis, and 2-month mortality.

Methods

This was a sub-study of the IHOP Study, a prospective observational study. Participants consisted of 184 adults admitted to Mulago Hospital in Kampala, Uganda who underwent evaluation for suspected TB and were followed for 2 months. Standardized questionnaires were administered to collect demographic and clinical data. PBMCs were isolated and analyzed using quantitative PCR to determine telomere length. The association between HIV infection, demographic and clinical characteristics, and telomere length was assessed, as were the associations between telomere length, TB diagnosis and 2-month mortality. Variables with a P≤0.2 in bivariate analysis were included in multivariate models.

Results

No significant demographic or clinical differences were observed between the HIV-infected and HIV-uninfected subjects. Older age (P<0.0001), male gender (P = 0.04), total pack-years smoked (P<0.001), alcohol consumption in the past year (P = 0.12), and asthma (P = 0.08) were all associated (P≤0.2) with shorter telomere length in bivariate analysis. In multivariate analysis adjusting for these five variables, HIV-positive participants had significantly shorter telomeres than HIV-negative participants (β = -0.0621, 95% CI -0.113 to -0.011, P = 0.02). Shortened telomeres were not associated with TB or short-term mortality.

Conclusions

The association between HIV infection and shorter telomeres suggests that HIV may play a role in cellular senescence and biological aging and that shorter telomeres may be involved in age-associated health complications seen in this population. The findings indicate a need to further research the impact of HIV on aging.

Premature aging and immune senescence in HIV-infected children

Supplemental Digital Content is available in the text

Several pieces of evidence indicate that HIV-infected adults undergo premature aging. The effect of HIV and antiretroviral therapy (ART) exposure on the aging process of HIV-infected children may be more deleterious since their immune system coevolves from birth with HIV.

HIV infection induces age-related changes to monocytes and innate immune activation in young men that persist despite combination antiretroviral therapy

OBJECTIVES

To compare the impact of HIV infection and healthy ageing on monocyte phenotype and function and determine whether age-related changes induced by HIV are reversed in antiretroviral treated individuals.

DESIGN

A cross sectional study of monocyte ageing markers in viremic and virologically suppressed HIV-positive males aged 45 years or less and age-matched and elderly (≥65 years) HIV-uninfected individuals.

METHODS

Age-related changes to monocyte phenotype and function were measured in whole blood assays ex vivo on both CD14(++)CD16(-) (CD14(+)) and CD14(variable)CD16(+) (CD16(+)) subsets. Plasma markers relevant to innate immune activation were measured by ELISA.

RESULTS

Monocytes from young viremic HIV-positive males resemble those from elderly controls, and show increased expression of CD11b (P < 0.0001 on CD14(+) and CD16(+)subsets) and decreased expression of CD62L and CD115 (P = 0.04 and 0.001, respectively, on CD14(+) monocytes) when compared with young uninfected controls. These changes were also present in young virologically suppressed HIV-positive males. Innate immune activation markers neopterin, soluble CD163 and CXCL10 were elevated in both young viremic (P < 0.0001 for all) and virologically suppressed (P = 0.0005, 0.003 and 0.002, respectively) HIV-positive males with levels in suppressed individuals resembling those observed in elderly controls. Like the elderly, CD14(+) monocytes from young HIV-positive males exhibited impaired phagocytic function (P = 0.007) and telomere-shortening (P = 0.03) as compared with young uninfected controls.

CONCLUSION

HIV infection induces changes to monocyte phenotype and function in young HIV-positive males that mimic those observed in elderly uninfected individuals, suggesting HIV may accelerate age-related changes to monocytes. Importantly, these defects persist in virologically suppressed HIV-positive individuals.

HIV infection and aging of the innate immune system

The increased life expectancy of HIV-infected individuals due to improved treatment has revealed an unexpected increase in non-AIDS comorbidities that are typically associated with older age including cardiovascular disease, dementia and frailty. The majority of these diseases arise as the result of dysregulated systemic inflammation, and both the aged and HIV-infected individuals exhibit elevated basal levels of inflammation. In the elderly, increased inflammation and age-related diseases are associated with a state of impaired immunity called immunosenescence, which is thought to result from a lifetime of immune stimulation. It is now apparent that HIV induces premature immunosenescence within T-cells; however, the impact of HIV on aging of cells of the innate arm of the immune system is unknown. Innate immune cells play a central role in inflammation and are thus critical for the pathogenesis of inflammatory diseases. Limited evidence suggests HIV infection mimics age-related changes to innate immune cells; however, the extent of this effect and the mechanism underlying these changes remain to be defined. This review focuses on the impact of HIV infection on the function and aging of innate immune cells and discusses potential drivers of premature immunosenescence including chronic endotoxaemia, residual viraemia, telomere attrition and altered cellular signalling.

The dual impact of HIV-1 infection and aging on naïve CD4 T-cells: additive and distinct patterns of impairment

HIV-1-infected adults over the age of 50 years progress to AIDS more rapidly than adults in their twenties or thirties. In addition, HIV-1-infected individuals receiving antiretroviral therapy (ART) present with clinical diseases, such as various cancers and liver disease, more commonly seen in older uninfected adults. These observations suggest that HIV-1 infection in older persons can have detrimental immunological effects that are not completely reversed by ART. As naïve T-cells are critically important in responses to neoantigens, we first analyzed two subsets (CD45RA⁺CD31⁺ and CD45RA⁺CD31^-) within the naïve CD4⁺ T-cell compartment in young (20–32 years old) and older (39–58 years old), ART-naïve, HIV-1 seropositive individuals within 1–3 years of infection and in age-matched seronegative controls. HIV-1 infection in the young cohort was associated with lower absolute numbers of, and shorter telomere lengths within, both CD45RA⁺CD31⁺CD4⁺ and CD45RA⁺CD31^-CD4⁺ T-cell subsets in comparison to age-matched seronegative controls, changes that resembled seronegative individuals who were decades older. Longitudinal analysis provided evidence of thymic emigration and reconstitution of CD45RA⁺CD31⁺CD4⁺ T-cells two years post-ART, but minimal reconstitution of the CD45RA⁺CD31^-CD4⁺ subset, which could impair de novo immune responses. For both ART-naïve and ART-treated HIV-1-infected adults, a renewable pool of thymic emigrants is necessary to maintain CD4⁺ T-cell homeostasis. Overall, these results offer a partial explanation both for the faster disease progression of older adults and the observation that viral responders to ART present with clinical diseases associated with older adults.

Premature onset of cardiovascular disease in HIV-infected individuals: the drugs and the virus

Life expectancy in HIV-infected individuals has been greatly enhanced through immunologic restoration and virologic suppression resulting from antiretroviral therapy. Current clinical HIV care in Western countries focuses on treatment of drug toxicities and prevention of comorbidities. These non-AIDS HIV-related comorbidities, such as cardiovascular disease, occur even in individuals with virologic suppression and manifest at an earlier age than when normally presenting in the general population. While traditional risk factors are present in many HIV-infected individuals who develop cardiovascular disease, the additional roles of HIV-related chronic inflammation and immune activation as well as chronic HIV viremia may be significant. This review provides current evidence for the contributions of the virus, in terms of both chronic viremia and its contribution via chronic low-level inflammation, immune activation, premature immune senescence and dyslipidemia, to the pathogenesis of HIV-related cardiovascular disease, and balances this against the propensity of specific antiretroviral therapies to cause cardiovascular disease, in particular through altered cholesterol metabolism.

Activation and coagulation biomarkers are independent predictors of the development of opportunistic disease in patients with HIV infection

BACKGROUND

Activation and coagulation biomarkers were measured within the Strategies for Management of Antiretroviral Therapy (SMART) trial. Their associations with opportunistic disease (OD) in human immunodeficiency virus (HIV)-positive patients were examined.

METHODS

Inflammatory (high-sensitivity C-reactive protein [hsCRP], interleukin-6 [IL-6], amyloid-A, and amyloid-P) and coagulation (D-dimer and prothrombin-fragment 1+2) markers were determined. Conditional logistic regression analyses were used to assess associations between these biomarkers and risk of OD.

RESULTS

The 91 patients who developed an OD were matched to 182 control subjects. Patients with an hsCRP level > or =5 microg/mL at baseline had a 3.5 higher odds of OD (95% confidence interval [CI], 1.5-8.1) than did those with an hsCRP level <1 microg/mL (P=.003, by test for trend) and patients with an IL-6 level > or =3 pg/mL at baseline had a 2.4 higher odds of OD (95% CI, 1.0-5.4) than did those with an IL-6 level <1.5 pg/mL (P=.02, by test for trend). No other baseline biomarkers predicted development of an OD. Latest follow-up hsCRP level for those with an hsCRP level > or =5 microg/mL (compared with a level <1 microg/mL; odds ratio [OR], 7.6; 95% CI, 2.0-28.5; [P=.002, by test for trend), latest amyloid-A level for those with an amyloid-A level > or =6 mg/L (compared with a level <2 mg/L; OR, 3.8; 95% CI, 1.1-13.4; P=.03, by test for trend), and latest IL-6 level for those with an IL-6 level > or =3 pg/mL (compared with a level <1.5 pg/mL; OR 2.4; 95% CI, 0.7-8.8; P=.04, by test for trend) were also associated with development of an OD.

CONCLUSIONS

Higher IL-6 and hsCRP levels independently predicted development of OD. These biomarkers could provide additional prognostic information for predicting the risk of OD.

Effect of tuberculosis on the survival of HIV-infected men in a country with low tuberculosis incidence

Evidence regarding the effect of tuberculosis (TB) on HIV disease progression at the population level remains inconclusive. We estimated the effect of incident TB on time to AIDS-related death, using a marginal structural Cox model. Between 1984 and 2005, 2882 HIV-infected men in the Multicenter AIDS Cohort Study contributed 21 914 person-years while followed for a median of 5.4 years. At study entry, the median CD4 cell count and HIV-1 RNA viral load were 533 cells/microl (interquartile range: 365-737) and 12, 953 copies/ml (interquartile range: 2453-48 540), respectively. This study was performed in a setting with a modest exposure to HAART; 8295 of 23 801 (35%) person-years were followed during the HAART era. Fifteen men incurred incident TB, yielding a TB incidence of 7 (95% confidence interval: 4-14) per 10 000 person-years and 1072 died of AIDS-related causes. Accounting for potential confounders, including CD4 cell count and viral load, the hazard of AIDS-related death was 2.4 times more for the person-time with TB compared to the person-time without TB (95% confidence interval: 1.2-4.7). Results underscore the importance of avoiding TB by using preventive interventions such as treatment of latent TB infection, particularly in populations with a large prevalence of HIV/TB co-infected individuals.

Telomerase activity, hTERT expression, and phosphorylation are downregulated in CD4(+) T lymphocytes infected with human immunodeficiency virus type 1 (HIV-1)

Human immunodeficiency virus type 1 (HIV-1) infection is characterized by a progressive decrease of CD4(+) T cells accompanied by other immune dysfunctions. Telomerase is transiently activated in lymphocytes during activation and is able to compensate for the progressive telomeric loss that occurs at each cell division, contributing to ensure the telomere length necessary for multiple proliferative events. The effect of HIV-1 infection on telomerase activity and on the expression of some of the factors involved in its regulation in CD4(+) T cells was investigated. Telomerase was found to be downregulated in both nuclear and cytoplasmic compartments, together with an impairment of human telomerase reverse transcriptase (hTERT) expression and of the cell machinery involved in hTERT phosporylation.

Tumor necrosis factor-alpha inhibits hTERT gene expression in human myeloid normal and leukemic cells

Telomerase catalytic subunit (hTERT) has been shown to play a critical role not only in telomere homeostasis but also in cellular survival, DNA repair, and genetic stability. In a previous study, we described that tumor necrosis factor-xalpha (TNFxalpha) induced in the leukemic KG1 cells a senescence state characterized by decreased hTERT activity followed by prolonged growth arrest, increasedx beta-galactosidase activity, telomere shortening, and major chromosomal instability. Interestingly, granulocyte-macrophage colony-stimulating factor (GM-CSF) abrogated all these events. In the present study, we show for the first time that TNFxalpha acts by inhibiting the hTERT gene in both normal CD34x+ cells and fresh leukemic cells. Using KG1 cells as a representative cellular model, we show that TNFxalpha induced sphingomyelin hydrolysis, ceramide production, and c-Jun N-terminal kinase (JNK) activation, all of which are critical components of TNFxalpha signaling, resulting in hTERT gene inhibition. Moreover, we provide evidence that the protective effect of GM-CSF is related to its capacity to interfere with both ceramide generation and ceramide signaling. Negative regulation of the hTERT gene may represent one mechanism by which TNFxalpha interferes with normal hemopoiesis.

The fusion of IGF I with stromal cell-derived factor I or alpha1 proteinase inhibitor alters their mitogenic or chemotactic activities while keeping their ability to inhibit HIV-1-gp120 binding

It has been previously reported that insulin-like growth factor I (IGF I) decreases in AIDS patients with wasting, a condition that is partially prevented by combined IGF I growth hormone therapy. By generating bifunctional proteins of IGF I and stromal cell-derived factor 1alpha (SDF-1alpha) or alpha1 proteinase inhibitor (API), two proteins known to prevent HIV infection, it may be possible to improve the therapeutic effectiveness of these compounds for the treatment of AIDS-mediated wasting. SDF-1alpha or the M351E-M358L mutant of API were attached at the C-terminal end of IGF I and synthesized by a stable insect cell expression technique. The IGF I-SDF-1alpha chimera reduced the enhancement of thymidine incorporation into bovine fetal erythroid cells observed in the presence of insect cell produced IGF I alone. It also decreased the SDF-1 and IGF I-stimulated hematopoietic cell migration, without losing the capacity to compete with the binding of HIV-1 (IIIB)-surface glycoprotein gp120. The IGF I-API chimera displayed the same mitogenic activity and a similar, but lower chemotactic activity than IGF I in the assays mentioned above. It had a comparable anti-elastase activity to that observed with a previously described IGF II-API fusion protein with the single mutation M351E. The binding of gp120 to a murine hematopoietic cell line was stimulated by human neutrophil elastase (25-100 nM) and inhibited by IGF I-API. In conclusion, the linkage of IGF I with SDF-1 or API can alter some biological functions of the single components of the chimera while keeping their ability to compete with HIV-1-gp120 binding.

Natural history of human immunodeficiency virus disease in southern India

There are few reports of the natural history of human immunodeficiency virus (HIV) infection from Asia. In a retrospective analysis of 594 patients (72.9% male; baseline CD4 cell count, 216 cells/microL) receiving care at YRG Center for AIDS Research and Education, a tertiary HIV referral center in southern India, the mean duration of survival from serodiagnosis was 92 months. Ninety-three percent of the patients acquired infection through heterosexual contact. The most common acquired immune deficiency syndrome-defining illnesses were pulmonary tuberculosis (49%; median duration of survival, 45 months), Pneumocystis carinii pneumonia (6%; median duration of survival, 24 months), cryptococcal meningitis (5%; median duration of survival, 22 months), and central nervous system toxoplasmosis (3%; median duration of survival, 28 months). Persons with a CD4 lymphocyte count of <200 cells/microL were 19 times (95% confidence interval [CI], 5.56-64.77) more likely to die than were those with CD4 cell count of >350 cells/microL. Patients who had > or =1 opportunistic infection were 2.6 times more likely to die (95% CI, 0.95-7.09) than were those who did not have an opportunistic infection. Antiretroviral therapy for patients with low CD4 lymphocyte counts improved the odds of survival (odds ratio, 5.37; 95% CI, 1.82-15.83).

Comparison of AIDS progression and survival in persons with pulmonary versus extrapulmonary tuberculosis in Los Angeles

The objective of this research was to compare the demographics, acquired immune deficiency syndrome (AIDS) progression, and survival in persons with AIDS with pulmonary tuberculosis (PTB) versus extrapulmonary tuberculosis (EPTB), because there are limited population-based data on this topic. A population-based longitudinal study with 3 years of follow-up was performed. Data were collected every 6 months from medical records of persons with AIDS and TB treated at private and public medical facilities throughout Los Angeles County (LAC). Participants included a population-based sample of 216 persons with AIDS and PTB and 166 persons with AIDS and EPTB (including 113 persons with both PTB and EPTB), with an AIDS diagnosis reported in 1993. Compared to persons with AIDS with PTB, persons with AIDS and EPTB were 2.2 times more likely to be Latino than white (95% confidence intervals [CIs]: 1.2, 4.0) and 1.7 times more likely to be foreign-born (95% CIs: 1.1, 2.5). Compared to persons with AIDS with PTB, persons with AIDS and EPTB had similar antiretroviral and PCP prophylaxis use; lower CD4 counts at time of AIDS diagnosis (p = 0.0004); no differences in CD4 counts over the total follow-up period (p = 0.4); higher rates of total opportunistic infections (OIs) (incidence density ratio [IDR] = 2.0; 95% CIs: 1.6, 2.4); and comparable survival curves (p = 0.07). Persons with AIDS and EPTB had a more complicated medical course with lower CD4 counts at time of AIDS diagnosis and more OIs over the follow-up period than persons with AIDS and PTB, however the survival profiles for the two groups were comparable.

Regulation of telomerase during human placental differentiation: a role for TGFbeta1

The transient tumor-like attributes of the first-trimester placenta anchor the developing embryo to the uterine wall thus establishing a vital link between the mother and the fetus. Dysregulation of this invasive behavior and/or controlled proliferation of the placenta is associated with abnormal pregnancies. Several of these diseased states also exhibit aberrant telomerase activity, among other pathophysiological manifestations. Considering the strong correlation between telomerase activity and tumorigenesis, it was of interest to see whether the crucial processes of trophoblast proliferation and differentiation were brought about through the modulation of telomerase. Using two in vitro model systems of trophoblast differentiation, we demonstrate here that telomerase activity is negatively regulated during placental differentiation. We further show that this modulation is at the level of transcription of hTERT. We also propose a role for TGF beta1 in regulating telomerase activity in differentiating trophoblasts by down-regulating the expression of hTERT at the transcriptional level.

Saquinavir up-regulates telomerase activity in lymphocytes activated with monoclonal antibodies against CD3/CD28

The present study describes the effect of the HIV protease inhibitor saquinavir on telomerase activity and interferon-gamma (IFN-gamma) production of nonadherent mononuclear cells (NA-MNC). Cells obtained from peripheral blood of healthy donors were exposed in vitro to a mixture of monoclonal antibodies against CD3 and CD28 membrane antigens in order to activate prevalently T cell subsets. Treatment with saquinavir was performed at the time of cell stimulation. Thereafter, NA-MNC were tested for telomerase activity (TRAP assay) and interferon-gamma production up to 7 days later. The results show that saquinavir up-regulates telomerase activity and IFN-gamma release in activated NA-MNC. These observations suggest that the anti-HIV effects of saquinavir could be accompanied by other immunopharmacological properties, influencing some aspects of the functional activity of immunocompetent cells. These include possible antagonistic effects against lymphocyte senescence, through telomerase activation, and a potentiating activity on the production of IFN-gamma following T cell activation.

Long-term effect of preventive therapy for tuberculosis in a cohort of HIV-infected Zambian adults

OBJECTIVE

To determine the long-term effect of preventive therapy (PT) for tuberculosis on the rates of tuberculosis, mortality and HIV progression.

METHODS

In a randomized controlled trial, 1053 HIV-positive Zambian adults received isoniazid (H) for 6 months, rifampicin plus pyrazinamide (RZ) for 3 months, or a placebo. CD4 percentage, neopterin, absolute lymphocyte count and haemoglobin were measured from enrolment (absolute CD4 cell counts from 12 months after enrolment). Because PT reduced the incidence of tuberculosis, eligible placebo subjects were offered H. Here, tuberculosis and mortality rates are compared in the three original arms (intention to treat) using data beyond the end of the trial (average follow-up 3 years; maximum 7 years).

RESULTS

There were 102 cases of tuberculosis and 281 deaths (rates 3.6 and 9.0/100 person-years, respectively). There was no significant difference between the tuberculosis rates in the H and RZ groups at any time. The effect of H/RZ on tuberculosis diminished over time (P = 0.011) but the cumulative risk of tuberculosis in the first 2.5 years was significantly lower in the H/RZ group than the placebo group (rate ratio 0.55; 95% confidence interval 0.32-0.93; P = 0.028). There was no significant effect of PT on mortality or progression markers. Tuberculosis was associated with an increased mortality (adjusted rate ratio 1.96; 95% confidence interval 1.21-3.18; P = 0.006).

CONCLUSIONS

Both PT regimens protect against tuberculosis for at least 2.5 years but appear to have no effect on HIV progression or mortality. These results may be used in cost-effectiveness models of PT.

AIDS related systemic non-Hodgkin's lymphoma

OBJECTIVE

To review the current literature on HIV associated non-Hodgkin's lymphoma.

METHODS

A comprehensive Medline/Pubmed search of articles pertaining to HIV associated non-Hodgkin's lymphoma as well as personal experience from the treatment of over 200 patients at the Chelsea and Westminster Hospital, one of the largest centres for the management of HIV disease in Europe.

CONCLUSION

High grade B cell non-Hogdkin's lymphoma is the second commonest tumour affecting people with HIV. The incidence of this tumour is not declining following the introduction of highly active antiretroviral therapy. Chemotherapy has been employed with modest success in this group of patients; however, the prognosis remains worse than for immunocompetent patients. Advances in molecular genetics and virology have led to a greater understanding of the biology of these tumours. However, these advances have yet to be translated into improvements in the clinical management of patients with AIDS associated non-Hodgkin's lymphoma.

Survival by AIDS defining condition in rural Uganda

OBJECTIVES

To report the initial AIDS defining conditions, CD4 lymphocyte counts around the time of AIDS diagnosis, and survival by AIDS defining condition in a population based cohort in rural Uganda.

METHODS

Participants in an HIV natural history cohort in rural Uganda were reviewed every 3 months at routine visits and at other times when they were ill. The date and nature of the first AIDS defining condition in participants developing AIDS during follow up between the start of the cohort in 1990 and the end of 1998 were noted. The CD4 count at, or within, 3 months of this time was recorded for those participants who developed AIDS (WHO stage 4) after 1993.

RESULTS

The median survival from developing AIDS to death was 9.3 months and the median CD4 lymphocyte count around the time of developing AIDS was 150 cells x 10(6)/l. The most frequent AIDS defining conditions were wasting syndrome, oesophageal candidiasis, and mucocutaneous herpes simplex virus infection (HSV) for more than 1 month. The median survival with wasting syndrome, Kaposi's sarcoma, and oesophageal candidiasis was less than 3.5 months; however, survival with cryptosporidial diarrhoea, chronic HSV, and extrapulmonary tuberculosis was greater than 20 months. There was little relation between CD4 count around the time of development of the AIDS defining condition and the median survival with that condition.

CONCLUSIONS

The survival for most AIDS defining conditions was generally shorter and the median CD4 lymphocyte count higher than studies reported from developed countries. However, the conditions with the longest survival (cryptosporidial diarrhoea, chronic HSV, and extrapulmonary tuberculosis) had a similar survival to that in developed countries and these conditions have a high background level in this population.

Pathogenesis of HIV-1 infection within bone marrow cells

Mononuclear phagocytic cells and CD4+ T lymphocytes represent the major targets for infection by HIV-1 in vivo. The most severe pathogenic features associated with HIV-1 infection can be attributed to malfunction or premature death of these cells that are of hematopoietic origin. Patients with acquired immunodeficiency syndrome (AIDS), suffer from many hematologic disorders, particularly those persons with long-term infection of HIV-1. These disorders include anemia, lymphocytopenia, thrombocytopenia and neutropenia. The mechanisms that lead to the induction of these disorders are multi-factorial. However, sufficient evidence has accumulated which suggests that HIV-1 infection of cells within the microenvironment of the bone marrow can lead to the induction of hematopoietic deficits. Most studies indicate that marrow-derived hematopoietic stem cells cannot be infected by HIV-1 until they undergo modest differentiation in order to express the appropriate receptors to enable virus entry and subsequent replication. Some cells within the mixed environment of the marrow stroma appear to support HIV-1 replication however. These cells include marrow microvascular endothelial cells, sometimes referred to as blanket cells, stromal fibroblasts, as well as mononuclear phagocytes. Our recent experiments suggest that the HIV-1 accessory protein, Vpr, plays some role in the activation of marrow-derived mononuclear phagocytes which appears to result in premature phagocytosis of non-adherent marrow cells present in the in vitro cultures. This phenomenon could account, in part, for the induction of cytopenias that are typical of individuals infected by HIV-1.

Telomeres and HIV disease

Telomere measurement, envisioned as a novel approach to elucidate T-cell dynamics in HIV disease, failed to reveal any consistent pattern in CD4+ T cells. By contrast, significant telomere shortening, as well as other hallmarks suggestive of replicative senescence, was observed within the CD8+ T-cell subset. Telomere studies have thus provided unanticipated insight into a novel facet of memory CD8+ T lymphocyte dynamics that may explain the exhaustion of the protective antiviral immune response. Strategies aimed at manipulating replicative senescence, therefore, offer unique approaches to immune reconstitution.