3'-Azido-3'-deoxythymidine (AZT) inhibits proliferation in vitro of human haematopoietic progenitor cells

Neurodevelopment among children exposed to HIV and uninfected in sub-Saharan Africa

INTRODUCTION

The population of 16 million children exposed to HIV and uninfected (CHEU) under 15 years of age continues to expand rapidly, and the estimated prevalence of CHEU exceeds 20% in several countries in sub-Saharan Africa with high HIV prevalence. Some evidence suggests that CHEU experience suboptimal neurodevelopmental outcomes compared to children born to women without HIV. In this commentary, we discuss the latest research on biologic and socio-behavioural factors associated with neurodevelopmental outcomes among CHEU.

DISCUSSION

Some but not all studies have noted that CHEU are at risk of poorer neurodevelopment across multiple cognitive domains, most notably in language and motor skills, in diverse settings, ages and using varied assessment tools. Foetal HIV exposure can adversely influence infant immune function, structural brain integrity and growth trajectories. Foetal exposure to antiretrovirals may also influence outcomes. Moreover, general, non-CHEU-specific risk factors for poor neurodevelopment, such as preterm birth, food insecurity, growth faltering and household violence, are amplified among CHEU; addressing these factors will require multi-factorial solutions. There is a need for rigorous harmonised approaches to identify children at the highest risk of delay. In high-burden HIV settings, existing maternal child health programmes serving the general population could adopt structured early child development programmes that educate healthcare workers on CHEU-specific risk factors and train them to conduct rapid neurodevelopmental screening tests. Community-based interventions targeting parent knowledge of optimal caregiving practices have shown to be successful in improving neurodevelopmental outcomes in children and should be adapted for CHEU.

CONCLUSIONS

CHEU in sub-Saharan Africa have biologic and socio-behavioural factors that may influence their neurodevelopment, brain maturation, immune system and overall health and wellbeing. Multidisciplinary research is needed to disentangle complex interactions between contributing factors. Common environmental and social risk factors for suboptimal neurodevelopment in the general population are disproportionately magnified within the CHEU population, and it is, therefore, important to draw on existing knowledge when considering the socio-behavioural pathways through which HIV exposure could impact CHEU neurodevelopment. Approaches to identify children at greatest risk for poor outcomes and multisectoral interventions are needed to ensure optimal outcomes for CHEU in sub-Saharan Africa.

Innate Immune Responses and Gut Microbiomes Distinguish HIV-Exposed from HIV-Unexposed Children in a Population-Specific Manner

In both high- and low-income countries, HIV-negative children born to HIV-positive mothers (HIV exposed, uninfected [HEU]) are more susceptible to severe infection than HIV-unexposed, uninfected (HUU) children, with altered innate immunity hypothesized to be a cause. Both the gut microbiome and systemic innate immunity differ across biogeographically distinct settings, and the two are known to influence each other. And although the gut microbiome is influenced by HIV infection and may contribute to altered immunity, the biogeography of immune-microbiome correlations among HEU children have not been investigated. To address this, we compared the innate response and the stool microbiome of 2-y-old HEU and HUU children from Belgium, Canada, and South Africa to test the hypothesis that region-specific immune alterations directly correlate to differences in their stool microbiomes. We did not detect a universal immune or microbiome signature underlying differences between HEU versus HUU that was applicable to all children. But as hypothesized, population-specific differences in stool microbiomes were readily detected and included reduced abundances of short-chain fatty acid-producing bacteria in Canadian HEU children. Furthermore, we did not identify innate immune-microbiome associations that distinguished HEU from HUU children in any population. These findings suggest that maternal HIV infection is independently associated with differences in both innate immunity and the stool microbiome in a biogeographical population-specific way.

Profile of hematological abnormalities and its correlation with absolute CD4 count and human immunodeficiency virus viral load in human immunodeficiency virus-infected patients in a tertiary care hospital

Background

A variety of hematological manifestations are seen at every stage of human immunodeficiency virus (HIV) infection, and they often pose a great challenge in the comprehensive management of acquired immunodeficiency syndrome. Anemia is the most common hematological abnormality associated with HIV infection. The severity and the incidence of cytopenia are usually correlated with the stage of the disease and underlying immune status if interpreted cautiously, especially if the patient is on regular follow-up. The primary objective of the present study was to understand the spectrum of hematological abnormalities in HIV-infected patients, whereas the secondary objective was to evaluate the correlation of hematological abnormalities with absolute CD4 count and HIV viral load.

Materials and Methods

The present cross-sectional descriptive study was conducted on 100 patients, aged 18 years and above, diagnosed with HIV infection and confirmed by Western blot or ELISA method. Both inpatients and outpatients at our tertiary care hospital were included in the study.

Results

Individuals with high viral load and low CD4 count had a higher prevalence of anemia. There was a statistically significant and directly proportionate decrease in the absolute CD4 count as the hemoglobin levels decreased (P = 0.004). In the present study, normocytic normochromic blood picture and anemia of chronic disease blood picture were more prevalent among the study participants. Individuals with high viral load and CD4 count <200 cells/mm³ had a higher rate of occurrence of coinfections. The correlation of absolute neutrophil count and thrombocytopenia with absolute CD4 count and HIV viral load was not statistically significant.

Conclusions

Complete blood counts and peripheral smear observations were significantly correlated with high HIV viral load and lower absolute CD4 cell counts and therefore can be suggested as economical alternatives for the evaluation of the status of HIV disease stage and its progression.

Determinants of anemia among pregnant mothers attending antenatal care in Dessie town health facilities, northern central Ethiopia, unmatched case -control study

INTRODUCTION

Anemia affects around 38.2% and 22% of pregnant women at a global and national level respectively. In developing countries, women start pregnancy with already depleted body stores of iron and other vitamins with significant variation of anemia within and between regions.

OBJECTIVE

To identify the determinants of anemia among pregnant mothers attending antenatal care in Dessie town health facilities, northern central Ethiopia.

METHODS

A health facility based unmatched case control study was conducted among 112 cases and 336 controls from January to March 2016 G.C. The sample size was determined by using Epi Info version 7.1.5.2. Study subjects were selected using consecutive sampling technique. Data were collected using a structured questionnaire, entered using Epi Data version 3.1 and analyzed using SPSS version 20. Bivariable and multivariable logistic regression model was used to see the determinants of anemia. Adjusted odds ratio (AOR) with 95% confidence interval (CI) and p-value<0.05 were used to see the significant association.

RESULTS

Failure to take dark green leafy vegetables per two weeks (AOR = 5.02, 95% CI: 2.16, 11.71), didn't take chicken per two weeks (AOR = 2.68, 95% CI: 1.22, 5.86), 1st trimester (AOR = 2.07, 95% CI: 1.12, 3.84), 3rd trimester (AOR = 2.96, 95% CI: 1.53, 5.72), HIV infection (AOR = 6.78, 95% CI: 2.28, 20.18) and medication (AOR = 3.57 95% CI: 1.60, 7.98) were positively associated with anemia.

CONCLUSIONS

Inadequate intake of dark green leafy vegetables, inadequate consumption of chicken, trimester of the current pregnancy, HIV infection and medication were the determinants of anemia among pregnant women. Therefore, anemia prevention strategy should include promotion of adequate intake of dark green leafy vegetables and chicken, increase meal pattern during the entire pregnancy and strengthen the prevention of mother to child HIV transmission/antenatal care programs.

Association Between the Occurrence of Adverse Drug Events and Modification of First-Line Highly Active Antiretroviral Therapy in Ghanaian HIV Patients

INTRODUCTION

Patients initiated on highly active antiretroviral therapy (HAART) generally remain on medication indefinitely. A modification in the HAART regimen may become necessary because of possible acute or chronic toxicities, concomitant clinical conditions, development of virological failure or the advent of adverse drug events. The study documents adverse drug events of HIV-positive Ghanaian patients with HAART modifications. It also investigates the association between documented adverse drug events and HAART modification using an unmatched case-control study design.

METHOD

The study was conducted in the Fevers Unit of the Korle Bu Teaching Hospital and involved patients who attended the HIV Care Clinic between January 2004 and December 2009. Data from 298 modified therapy patients (cases) were compared with 298 continuing therapy patients (controls) who had been on treatment for at least 1 month before the end of study. Controls were sampled from the same database of a cohort of HIV-positive patients on HAART, at the time a case occurred, in terms of treatment initiation ±1 month. Data were obtained from patients' clinical folders and the HIV clinic database linked to the pharmacy database. The nature of the documented adverse drug events of the cases was described and the association between the documented adverse drug events and HAART modification was determined by logistic regression with reported odds ratios (ORs) and their 95 % confidence interval (CI).

RESULTS

Among the 298 modified therapy patients sampled in this study, 52.7 % of them had at least one documented adverse drug event. The most documented adverse drug event was anaemia, recorded in 18.5 % of modified therapy patients, all of whom were on a zidovudine-based regimen. The presence of documented adverse drug events was significantly associated with HAART modification [adjusted OR = 2.71 (95 % CI 2.11-3.48), p < 0.001].

CONCLUSION

Among HIV patients on HAART, adverse drug events play a major role in treatment modification. Occurrence of adverse drug events may be used as a predictor for possible therapy modification. We recommend the institution of active pharmacovigilance in HIV treatment programmes as it permits the proper identification and characterisation of drug-related adverse events. This can help develop approaches towards their management and also justify therapy modifications.

The Immune System of HIV-Exposed Uninfected Infants

Infants born to human immunodeficiency virus (HIV) infected women are HIV-exposed but the majority remains uninfected [i.e., HIV-exposed uninfected (HEU)]. HEU infants suffer greater morbidity and mortality from infections compared to HIV-unexposed (HU) peers. The reason(s) for these worse outcomes are uncertain, but could be related to an altered immune system state. This review comprehensively summarizes the current literature investigating the adaptive and innate immune system of HEU infants. HEU infants have altered cell-mediated immunity, including impaired T-cell maturation with documented hypo- as well as hyper-responsiveness to T-cell activation. And although prevaccination vaccine-specific antibody levels are often lower in HEU than HU, most HEU infants mount adequate humoral immune response following primary vaccination with diphtheria toxoid, haemophilus influenzae type b, whole cell pertussis, measles, hepatitis B, tetanus toxoid, and pneumococcal conjugate vaccines. However, HEU infants are often found to have lower absolute neutrophil counts as compared to HU infants. On the other hand, an increase of innate immune cytokine production and expression of co-stimulatory markers has been noted in HEU infants, but this increase appears to be restricted to the first few weeks of life. The immune system of HEU children beyond infancy remains largely unexplored.

Influence of new antiretrovirals on hematological toxicity in HIV-exposed uninfected infants

Maternal combined antiretroviral therapy (cART) successfully prevents HIV mother-to-child transmission but also causes hematological toxicity in the HIV-exposed uninfected (HEU) infant. We performed a single-center prospective observational study. Hematological toxicity during the first year of life (at 3 and 6 weeks, and 3, 6, and 12 months) was compared between HEU infants born in two different time periods: P1 (2000-2001) and P2 (2007-2013). Mother-infant pairs in P1 (n = 55) and P2 (n = 48) mainly differed in maternal ethnic origin, HIV route of transmission, and cART regimens. Anemia and neutropenia were both less common in P2 than P1, albeit not significantly. Earlier normalization of red blood cell mean corpuscular volume levels in P2 infants suggests that current cART maternal regimens and shorter neonatal prophylaxis are less toxic. Leukocyte, lymphocyte, and platelet counts remained within normal values during follow-up, without differences between groups.

CONCLUSION

New cART regimens have had very little impact on the hematological toxicity in HEU infants.

WHAT IS KNOWN

• Antiretroviral drugs during pregnancy and the neonatal period very effectively prevent mother-to-child transmission of HIV infection. • Hematological toxicity has been widely reported among HIV-exposed uninfected children. What is New: • In HIV-exposed uninfected children, hematological toxicity is still mainly caused by exposure to zidovudine. • New antiretroviral drugs have very little impact on hematological toxicity among HIV-exposed uninfected children.

Effect of G-CSF and M-CSF on the in vitro Toxicity Associated with Zidovudine in Normal Human Bone Marrow Haematopoietic Progenitor Stem Cells

Zidovudine, the antiviral drug used in the treatment of acquired immunodeficiency syndrome (AIDS), causes toxicity to the haematopoietic system. Although use of the haematopoietic growth factors, GM-CSF and erythropoietin have been investigated in clinical trials to modulate antiviral toxicity, there is scant data which supports their ability to ameliorate zidovudine induced toxicity on haematopoietic progenitor cells when combined in vitro. We describe here the results of studies designed to evaluate the capacity of additional haematopoietic factors such as granulocyte-colony stimulating factor (G-CSF) and macrophage-colony stimulating factor (M-CSF) to modulate zidovudine-induced toxicity on G-CSF and M-CSF dependent-colony formation in the presence or absence of zidovudine in vitro. These factors were also studied combined with erythropoietin in culture for the early erythroid progenitor BFU-E using adherent, T-cell, depleted normal human bone marrow cells in the presence or absence of zidovudine. In the presence of zidovudine at the concentration producing 50% inhibition of G- and M-CSF dependent colony formation, (5 × 10−5M), dose-escalation of either G-CSF or M-CSF failed to ameliorate zidovudine toxicity. However, in the presence of zidovudine at the concentration that produces 50% inhibition of BFU-E (5 × 10−9M), and optimal erythropoietin (1 unit ml−1), G-CSF ameliorated zidovudine inhibition of BFU-E, which was not observed with M-CSF. In the presence of erythropoietin, G-CSF increased significantly normal BFU-E. These studies indicate that G-CSF may be useful in ameliorating zidovudine-induced anaemia and suggest G-CSF may act as a synergistic factor to enhance erythropoietin to support the growth of erythroid progenitors in conditions where erythropoitin is ineffective.

Effect of IL-1, IL-6, GM-CSF and Erythropoietin on the in vitro Toxicity Associated with AZT on Human Bone Marrow Haematopoietic Progenitor Stem Cells: CFU-GM and BFU-E

The drug azidothymidine (AZT), a synthetic thymidine analogue, has been used in the treatment of acquired immunodeficiency syndrome (AIDS). Clinical use of AZT has induced haematopoietic toxicity manifested by anaemia, neutropenia, and overall bone marrow suppression. Cytokines/growth factors, such as erythropoietin (EPO), granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin-1 (IL-1), interleukin-6 (IL-6), are agents responsible for the growth and regulation of normal haematopoiesis by influencing various classes of haematopoietic progenitors. We report the results of studies designed to investigate the capacity of these factors to influence the toxicity of AZT. Low density, ≤ 1.077 g/cm3, adherent and/or T-cell depleted normal human marrow cells were co-cultured in the presence or absence of AZT and the appropriate growth factor, i.e. EPO for the early erythroid haematopoietic colony-forming progenitor stem cell (BFU-E) and GM-CSF for the granulocyte–macrophage haematopoietic colony-forming progenitor stem cell (CFU-GM), in dose escalation studies. Additional experiments measured the effect of increasing doses of the cytokines IL-1 and IL-6, alone or in combination in the presence of increasing doses of either EPO or GM-CSF. When comparing the rate of AZT-induced inhibition of BFU-E in vitro, EPO alone (from 2 to 10 U/ml) did not reduce the magnitude of AZT toxicity on BFU-E. GM-CSF alone (up to 1000 U/ml) was ineffective in reversing AZT toxicity on CFU-GM; however, in the presence of either IL-1 and IL-6, AZT toxicity was decreased. These results indicate that certain cytokines/growth factors such as IL-1 or IL-6 in combination with EPO or GM-CSF, but not EPO or GM-CSF alone, may be effective in ameliorating AZT bone marrow toxicity; therefore the use of specific cytokines may be warranted as adjuvant therapy in AIDS.

Maternal Lopinavir/Ritonavir Is Associated with Fewer Adverse Events in Infants than Nelfinavir or Atazanavir

Combination antiretroviral therapy (cART) is successfully used for prevention of perinatal HIV transmission. To investigate safety, we compared adverse events (AE) among infants exposed to different maternal cART regimens. We reviewed 158 HIV-uninfected infants born between 1997 and 2009, using logistic regression to model grade ≥1 AE and grade ≥3 AE as a function of maternal cART and confounding variables (preterm, C-section, illicit drug use, race, ethnicity, infant antiretrovirals, and maternal viremia). Frequently used cART regimens included zidovudine (63%), lamivudine (80%), ritonavir-boosted lopinavir (37%), nelfinavir (26%), and atazanavir (10%). At birth, anemia occurred in 13/140 infants (9%), neutropenia in 27/107 (25%), thrombocytopenia in 5/133 (4%), and liver enzyme elevation in 21/130 (16%). Corresponding rates of AE at 4 weeks were 59/141 (42%), 54/130 (42%), 3/137 (2%), and 3/104 (3%), respectively. Serious AE (grade ≥ 3) exceeded 2% only for neutropenia (13% at birth; 9% at 4 weeks). Compared with infants exposed to maternal lopinavir/ritonavir, infants exposed to nelfinavir and atazanavir had a 5-fold and 4-fold higher incidence of AE at birth, respectively. In conclusion, hematologic and hepatic AE were frequent, but rarely serious. In this predominantly protease inhibitor-treated population, lopinavir/ritonavir was associated with the lowest rate of infant AE.

Hematological Indices at Birth of Infants of HIV-Positive Mothers Participating in a Prevention of Mother-to-Child Transmission Program

BACKGROUND

The mother-to-child transmission of HIV, which accounts for 90% of infections in children, has been reduced markedly through the use of antiretroviral drugs by pregnant women and their newborns. Changes to the World Health Organization guidelines support further extension of the prevention of mother-to-child transmission programs with increased risk of toxicity on the fetuses.

AIM

To determine the hematological indices at birth of infants exposed in utero to maternal antiretroviral drugs.

METHOD

A comparative analytical study of 126 neonates whose blood samples were analyzed to determine their hematological indices.

RESULT

The hemoglobin, hematocrit, the total white blood cell (WBC) count and absolute neutrophil count (ANC) were significantly lower in infants of HIV-positive mothers. The total WBC and ANC were also significantly lower in the highly active antiretroviral therapy. HAART group and those exposed to maternal drugs for <1 year.

CONCLUSION

There are significant changes in the hematological indices of infants of HIV-positive mothers at birth.

Determinants of Anemia Among Human Immunodeficiency Virus-Positive Adults at Care and Treatment Clinics in Dar es Salaam, Tanzania

Anemia is often a comorbidity of human immunodeficiency virus (HIV) infection. Many cross-sectional studies have been conducted on anemia and HIV, but few, if any, have addressed incidence of anemia prospectively. A longitudinal analysis was conducted in 48,068 nonpregnant HIV-infected adults in Dar es Salaam, Tanzania, seen at Management and Development for Health-U.S. President's Emergency Plan for AIDS Relief HIV care and treatment programs between 2004 and 2011. Almost 56% (N = 27,184) of study participants had anemia (hemoglobin < 11 g/dL) at the time of enrollment at the clinic. Female gender, low body mass index (BMI), low CD4 T-cell count, high levels of liver enzyme alanine aminotransferase, antiretroviral treatment (ART) regimens, and concurrent tuberculosis treatment were all independently significantly associated with an increased risk of anemia. Low BMI and low CD4 T-cell count were independently significantly associated with an increased risk for iron deficiency anemia (IDA). Higher BMI status and ART use were associated with recovery from anemia. Anemia, including IDA, is a comorbidity that is associated with other adverse consequences (e.g., low BMI and CD4 T-cell count) among individuals with HIV infection, including those on ART. Interventions to prevent anemia and its complications need to be examined in the context of future studies.

HIV-exposed uninfected children: a growing population with a vulnerable immune system?

Through the successful implementation of policies to prevent mother-to-child-transmission (PMTCT) of HIV-1 infection, children born to HIV-1-infected mothers are now much less likely to acquire HIV-1 infection than previously. Nevertheless, HIV-1-exposed uninfected (HEU) children have substantially increased morbidity and mortality compared with children born to uninfected mothers (unexposed uninfected, UU), predominantly from infectious causes. Moreover, a range of phenotypical and functional immunological differences between HEU and UU children has been reported. As the number of HEU children continues to increase worldwide, two questions with clear public health importance need to be addressed: first, does exposure to HIV-1 and/or ART in utero or during infancy have direct immunological consequences, or are these poor outcomes simply attributable to the obvious disadvantages of being born into an HIV-affected household? Secondly, can we expect improved maternal care and ART regimens during and after pregnancy, together with optimized infant immunization schedules, to reduce the excess morbidity and mortality of HEU children?

A review of the use of blood and blood products in HIV-infected patients

Despite numerous publications on the appropriate use of blood and blood products, few specifically consider the role of transfusion in the management of HIV. This review is a synthesis of conditions encountered in the management of HIV-infected patients where the transfusion of blood or blood products may be indicated. A consistent message emerging from the review is that the principles of transfusion medicine do not differ between HIV-negative and -positive patients. The aim of the review is to provide clinicians with a practical and succinct overview of the haematological abnormalities and clinical circumstances most commonly encountered in the HIV setting, while focusing on the rational and appropriate use of blood and blood products for HIV patients. Important ethical considerations in dealing with both the collection and transfusion blood and blood products in the HIV era have also been addressed.

Lower respiratory tract infections among human immunodeficiency virus-exposed, uninfected infants

OBJECTIVES

To evaluate whether maternal HIV disease severity during pregnancy is associated with an increased likelihood of lower respiratory tract infections (LRTIs) in HIV-exposed, uninfected infants.

METHODS

HIV-exposed, uninfected, singleton, term infants enrolled in the NISDI Perinatal Study, with birth weight >2500g were followed from birth until 6 months of age. LRTI diagnoses, hospitalizations, and associated factors were assessed.

RESULTS

Of 547 infants, 103 (18.8%) experienced 116 episodes of LRTI (incidence=0.84 LRTIs/100 child-weeks). Most (81%) episodes were bronchiolitis. Forty-nine (9.0%) infants were hospitalized at least once with an LRTI. There were 53 hospitalizations (45.7%) for 116 LRTI episodes. None of these infants were breastfed. The odds of LRTI in infants whose mothers had CD4% <14 at enrollment were 4.4 times those of infants whose mothers had CD4% ≥29 (p=0.003). The odds of LRTI in infants with a CD4+ count (cells/mm(3)) <750 at hospital discharge were 16.0 times those of infants with CD4+ ≥750 (p=0.002). Maternal CD4+ decline and infant hemoglobin at the 6-12 week visit were associated with infant LRTIs after 6-12 weeks and before 6 months of age.

CONCLUSIONS

Acute bronchiolitis is common and frequently severe among HIV-exposed, uninfected infants aged 6 months or less. Lower maternal and infant CD4+ values were associated with a higher risk of infant LRTIs. Further understanding of the immunological mechanisms of severe LRTIs is needed.

Antiretroviral-related hematologic short-term toxicity in healthy infants: implications of the new neonatal 4-week zidovudine regimen

Recent updates of the guidelines on the prevention of human immunodeficiency virus mother-to-child transmission have shortened the neonatal zidovudine prophylactic regimens from 6 to 4 weeks. We present a prospective observational study in a large cohort of mother-infant pairs and report that the 4-week regimen allows an earlier recovery of the anemia in these otherwise healthy infants.

Stem cells in myelotoxicity

Myelotoxicity describes bone marrow failure due to adverse effect of xenobiotic on hematopoiesis. Hematopoiesis is a complex system in which pluripotent hematopoietic stem cells (PHSCs) differentiate into many highly specialized circulating blood cells involving the interaction of many cell types as well as the interaction of local and systemic growth factors. With respect to blood cell formation, two functional systems must be considered: the hematopoietic stem cells (PHSCs) and the progenitor cells, on one hand, and the stromal cells, which constitute the hematopoietic environment niche, on the other hand. There are three types of assays for hematopoietic progenitor clonogenic assays useable in myelotoxicology: CFU-GM assay for Colony Forming Unit Granulocyte and Macrophage, BFU-E assay for Burst Forming Unit Erythroid, and CFU-MK assay for Colony Forming Unit Megakaryocyte from several species as well as from murine as from mammalian and human. Clonogenic assays have been used to detect myelotoxicity induced by chemicals, drug, food and environmental contaminants. Designs and applications are described in this review.

Trimethoprim-sulfamethoxazole exposure alters ex vivo function of B lymphocytes isolated from human immunodeficiency virus-infected patients receiving Zidovudine

STUDY OBJECTIVE

To determine if exposure to trimethoprim-sulfamethoxazole (TMP-SMX) causes a defect in peripheral B-cell function among patients with the human immunodeficiency virus (HIV) who are receiving zidovudine antiretroviral therapy.

DESIGN

Prospective, single-center, single-group, case-crossover design with a 4-week exposure period.

SETTING

University-affiliated infectious diseases outpatient clinic.

PATIENTS

Fourteen HIV-infected adult men receiving zidovudine, who had CD4(+) cell counts above 350 cells/mm(3) and undetectable viral loads.

INTERVENTION

Patients were administered a 28-day course of TMP 160 mg-SMX 800 mg/day (one double-strength tablet/day). Peripheral blood mononuclear cells (PBMCs) were obtained and isolated before and after exposure to TMP-SMX. Cells were cultured ex vivo with three mitogens of differing immunologic properties: pokeweed mitogen ([PWM] T-cell-dependent B-cell mitogen), Staphylococcus aureus Cowan ([SAC] T-cell-independent B-cell mitogen), and phytohemagglutinin A ([PHA] T-cell mitogen). Functionality of the B and T lymphocytes was then assessed.

MEASUREMENTS AND MAIN RESULTS

Proliferative capacity, cytokine secretion, and antibody production were measured and compared before and after TMP-SMX exposure. Reduced proliferative capacities of both PBMC and B cells stimulated with mitogens were observed at the 3-day culture time point in response to PWM, PHA, and SAC (p=0.029, 0.028, and 0.026, respectively). Proliferative capacity at day 7 of culture was not significantly different for any condition examined. Cytokine production was not altered by combination drug exposure after 10 days of culture when cells were stimulated with either PWM or PHA. Although antibody responses to PWM and PHA were similar, total immunoglobulin G concentration was lower in cells stimulated with SAC in samples obtained after TMP-SMX regimen completion compared with those obtained before exposure (p=0.005).

CONCLUSION

Although these data were affected by limitations in power and study design, they suggest that peripheral B-lymphocyte function is altered as a result of TMP-SMX exposure in HIV-infected patients concurrently receiving zidovudine. Further study of this effect is warranted.

[Anaemia and neutropenia in a cohort of non-infected children of HIV-positive mothers]

INTRODUCTION

Mother-to-child HIV transmission is currently around 1% in western countries, due to prevention measures. Antiretroviral drugs do have adverse effects, anaemia and myelosupression caused by AZT being the most observed effects. In the present study, we analyse the prevalence of anaemia and neutropenia in an uninfected children cohort born to HIV-infected women.

MATERIAL AND METHODS

We followed up 623 uninfected children belonging to the FIPSE cohort according to standardised protocols. This cohort groups 8 hospitals from Madrid and follows up HIV infected pregnant women and their children. Anaemia and neutropenia were defined according to the ACTG (AIDS Clinical Trails Group) toxicity tables. Children were classified according to prematurity, ethnic origin, birth weight, withdrawal syndrome, in-utero treatment and neonatal prophylaxis. Categorical variables were compared with the chi2 or the Fisher tests.

RESULTS

Anaemia was observed in 188 (30.1%) children during follow-up and 161 (25.8%) had anaemia grade 2 or higher. Prematurity (p < 0.001), low birth weight (p = 0.005) and Highly Active Antiretroviral Treatment (HAART) with Protease Inhibitors (p = 0.016) were associated with higher percentages of anaemia in children. Nadir haemoglobin values were reached by 6 weeks of life and anaemia was transient and disappeared by six months of age. Neutropenia was present in 41.9% (261 children) and 22.7% of the children had moderate-severe neutropenia. Prematurity was again associated with neutropenia (p = 0.01) and low birth weigh was associated only with moderate-severe neutropenia (p = 0.023). African infants had a higher percentage of neutropenia than the rest of the children (50% vs. 44%), although the differences were not significant. The type of in-utero treatment did not appear to influence the neutropenia. Neutropenia was still present in 12.5% of infants at 18 months of age. The type of neonatal prophylaxis to prevent mother-to-child transmission (monotherapy, dual therapy or triple therapy) did not influence either cytopenia.

CONCLUSION

In our series, the proportion of children with anaemia is high: 30.1% Prematurity, low birth weight and HAART with IP were associated with a higher proportion of anaemia, which was transient and had little clinical relevance. The proportion of children with neutropenia was higher (41.9%) and was associated with prematurity, low birth weight and African origin. The type of neonatal prophylaxis does not seem to influence the development of cytopenias. Persistence of neutropenia (without clinical significance) was observed in a small percentage of the children 12.5%, at 18 months of age.

Maternal antiretrovirals and hepatic enzyme, hematologic abnormalities among human immunodeficiency virus type 1-uninfected infants: the NISDI perinatal study

OBJECTIVES

To assess hepatic enzyme (HE) and hematologic abnormalities among human immunodeficiency virus-1-uninfected infants according to maternal antiretroviral regimen during pregnancy.

STUDY DESIGN

In a prospective cohort, HE and hematologic values of human immunodeficiency virus-1-uninfected, term infants with hospital discharge (HD) within 6 days after birth were evaluated. Maternal antiretroviral regimens were categorized as: 1 or 2 nucleoside reverse transcription inhibitors (NRTIs), highly active antiretroviral therapy (HAART)/protease inhibitor (PI), or HAART/non-NRTI.

RESULTS

Among 503 infants, 63% and 24% had HE and hemoglobin abnormalities, respectively, at HD. Most or all HE and hemoglobin abnormalities (96-100%) were grade 1 or 2. At HD, infants with maternal HAART/PI or HAART/non-NRTI were more likely to have elevated HE [adjusted odds ratio (AOR): 1.9, 2.4, respectively] compared with infants whose mothers received 1 or 2 NRTIs. Infants with maternal HAART/PI were less likely to have abnormal hemoglobin values at HD (AOR, 0.5) when compared with those whose mothers received 1 or 2 NRTIs. Persistently abnormal hemoglobin and HE values decreased with time, such that <10% of infants had abnormalities at 6 months of age.

CONCLUSIONS

Maternal receipt of HAART regimens was associated with an increased risk of HE abnormalities, and maternal HAART/PI was associated with a lower risk of abnormal hemoglobin values, at HD. Abnormalities of HE and hemoglobin were generally mild and transient.

Mitochondrial disease in the offspring as a result of antiretroviral therapy

Nucleoside analogue reverse transcriptase inhibitors (NRTIs) have substantially lowered the risk of the mother-to-child transmission of HIV. Evidence of mitochondrial toxicity in vitro, in animal models and in adult HIV-infected patients, has raised concern about the perinatal safety of these antiretrovirals. In zidovudine-exposed, but HIV-uninfected infants, transient anaemia and additional long-term blood abnormalities (neutropenia, thrombopenia and lymphopenia) and hyperlactatemia have been documented. The overall risk of mortality and congenital abnormalities does not appear to be increased, but rare mitochondrial events cannot be excluded for lack of statistical power. French data suggest an above background incidence of mitochondrial symptomatology. Preclinical data demonstrate zidovudine also to be a carcinogen. Long-term systematic follow-up of exposed babies in large cohorts is needed, as are randomised trials with NRTIs carrying a lower risk of mitochondrial toxicity.

Pattern expression of glycan residues in AZT-treated K562 cells analyzed by lectin cytochemistry

The present paper shows that human chronic myeloid (K562) cells exposed 3 h to 20 microM 3'-azido-3'-deoxythymidine (AZT) exhibit marked variations of the oligosaccharide moiety of glycoconjugates. These changes were analyzed by confocal fluorescence microscopy, upon incubation of control and AZT-treated cells with biotin-lectin conjugates to visualize cell surface glycans or total glycans after cells permeabilization. In addition, cell fluorescence distribution of the biotinylated lectins, localized with streptavidin conjugates labeled with Alexa Fluor 488, was analyzed by flow cytometry. The results obtained show significant variations on the expression/distribution of membrane surface glycans as detected by both WGA and SNA, two lectins that recognize primarily cellular internal membrane glycolipids. A further interesting result was the significant increase of N-acetylglucosamine linked glycans localized either at the cell surface or intracellularly but only in K562 cells exposed to AZT. On the whole, our data demonstrate that AZT alters both lipid and N-linked glycosylations thus confirming previous observations, from our laboratory and from other Authors, that the drug impair the nucleotide-sugar import in the Golgi's lumen. AZT does also alter the O-linked glycosylations that occur in the Golgi complex since these reactions require the incorporation of sialic acid, GlcNAc and GalNAc all of which are sensitive to the drug.

Zidovudine use but not weight-based ribavirin dosing impacts anaemia during HCV treatment in HIV-infected persons

Anaemia during peginterferon (PEG-IFN) and ribavirin (RBV) therapy is common in human immunodeficiency virus/hepatitis C virus (HIV/HCV)-coinfected patients despite the use of lower doses of RBV than are recommended for HIV-seronegative persons. In addition, concurrent zidovudine (ZDV) may exacerbate the anaemia caused by PEG-IFN and RBV. We retrospectively analysed the incidence of anaemia, RBV dose reduction and epoetin-alpha (EPO) use among coinfected patients treated with PEG-IFN and weight-based RBV (800-1400 mg/day) who enrolled in two clinical trials and had haemoglobin (Hb) levels assessed at baseline and after 4 and/or 12 weeks of HCV treatment. Overall, 217 patients were included; pre-treatment Hb levels (mean 14.7 g/dL) were similar in all patients, including ZDV users (29% of patients). After 4 weeks of therapy, the mean Hb decline was greater among ZDV recipients (3.13 g/dL) compared with those on other anti-retroviral treatment (ART) (2.13 g/dL) or on no ART (1.47 g/dL) (P < 0.0001). RBV dose reduction and EPO use were more common in patients taking ZDV compared with those not taking ZDV (P < 0.0001). RBV dose was not associated with Hb reduction, RBV dose reduction or EPO use. Virologic response after 12 weeks of therapy and the treatment discontinuation rate did not differ by ZDV use. The use of ZDV but not weight-based RBV dosing was associated with an increased risk of anaemia, RBV dose reduction or EPO use in coinfected patients treated with PEG-IFN/RBV. However, ZDV use was not associated with higher rates of treatment discontinuation or lower early virologic response rates. HIV and hepatitis C care providers should be cognizant of these data.

Combination exposure to zidovudine plus sulfamethoxazole-trimethoprim diminishes B-lymphocyte immune responses to Pneumocystis murina infection in healthy mice

We have previously shown that zidovudine plus sulfamethoxazole-trimethoprim exposure decreases immune cell populations in the bone marrow of healthy mice by inducing apoptosis. The hypothesis of the current work was that this toxicity would have an adverse impact on the immune response. To determine this, BALB/c mice were treated with zidovudine, sulfamethoxazole-trimethoprim, the combination of both drugs, or vehicle only (control) via oral gavage for 21 days. On day 4 after dosing completion, the mice were infected intratracheally with 1x10(7) Pneumocystis murina organisms. Immune cell populations (in lung digest, bronchoalveolar lavage fluid, tracheobronchial lymph node, and bone marrow samples), the lung Pneumocystis burden, and serum Pneumocystis-specific antibody titers were determined at days 6, 10, and 20 postinfection. While total bone marrow cellularity was recovered by day 6 postinfection in the combination exposure group, B-cell numbers did not recover until 10 days postinfection, primarily due to the persistent depletion of the late pre-B-cell phenotype. The numbers of CD4+ and CD8+ T cells, as well as the numbers of total B cells and activated B cells in tracheobronchial lymph nodes, were decreased at days 10 and 20 as a result of zidovudine plus sulfamethoxazole-trimethoprim exposure compared to the numbers in the control group. No significant differences in lung lavage or lung digest cell populations were observed. There was a trend of a delay in Pneumocystis clearance in the combination treatment group, and Pneumocystis-specific serum immunoglobulin G titers were reduced at day 20 postinfection. Together, these data indicate that the combination of zidovudine and sulfamethoxazole-trimethoprim adversely affects the humoral immune response to Pneumocystis.

Zidovudine plus sulfamethoxazole–trimethoprim adversely affects B lymphocyte maturation in bone marrow of normal mice

Sulfamethoxazole-trimethoprim and zidovudine (AZT), drugs used often in combination in patients infected with HIV, were investigated for their effects on B cell development in a mouse model. BALB/c mice were randomized to receive oral doses of AZT, sulfamethoxazole-trimethoprim, or the combination via oral gavage for up to 28 days. Immune cell populations in the spleen, lung, and peripheral blood were examined, and toxicity to B lineage subtypes in the bone marrow was investigated by phenotypic analysis via flow cytometry. Pre-pro-B, pro-B, early pre-B, and late pre-B cells were assayed for apoptosis and analyzed for cell cycle profile. Total as well as B cell splenic and bone marrow cellularities were significantly decreased by using the drugs concomitantly, while B cell populations in the lungs and percentage in the peripheral blood were not affected. Combination therapy caused significant increases in apoptosis in B cells and granulocytes in the bone marrow, with the late pre-B cell population being the most depleted. The proliferative expansion and differentiation of early pre-B cells (B220+/CD43+/BP-1+/HSA+) to the late pre-B cell (B220+/CD43-/IgM-) stage was blocked, with early pre-B cells accumulating in the proliferative phases of the cell cycle. This apoptosis increase is likely due to elevated blood sulfamethoxazole concentrations that were observed in mice also receiving AZT. Concurrent sub-chronic administration of AZT and sulfamethoxazole-trimethoprim adversely affected B lymphocyte development in mouse bone marrow.

Haematological parameters of HIV-1-uninfected infants born to HIV-1-infected mothers

AIM

To investigate haematological parameters in infants born to HIV-1-infected mothers and exposed to combination antiretroviral therapy (ART) used to prevent mother-to-child transmission (MTCT).

METHODS

A 2-y single-centre follow-up study performed in 109 infants born to HIV-1-positive mothers. Exclusion criteria for the infants were HIV-1 infection, perinatal death, or insufficient information. Haematological parameters of the remainder of 92 infants born to HIV-1-infected mothers and exposed to ART in utero and neonatally were compared with 75 matched non-ART-exposed children.

RESULTS

Transmission rate of HIV-1 was 1.8% and occurred when the mother was not compliant with the treatment. In the HIV-1/ART-exposed children there was a long-lasting reduction in absolute neutrophil counts (ANC) until at least 8 mo of age. According to PACTG toxicity scores, 16 infants were suffering from grade II or more (moderate-to-severe) toxicity of ART on ANC. In a multivariable analysis of maternal and neonatal risk factors, pregnancy duration was correlated with moderate-to-severe toxicity on ANC. There were no clinical implications detected, e.g. increased infections or antibiotic treatment.

CONCLUSION

ART is successful in preventing MTCT, but alterations in haematological parameters may persist for a long period. The clinical implications remain uncertain. This suggestion increases the importance to continue prospective follow-up on the haematological parameters in ART/HIV-exposed children.

Maternal and infant factors and lymphocyte, CD4 and CD8 cell counts in uninfected children of HIV-1-infected mothers

OBJECTIVE

To evaluate the effects of antiretroviral treatment (ART) for mother-to-child transmission of HIV and infant/maternal characteristics on total lymphocytes (TLC) and lymphocyte subsets in uninfected children of HIV-1-infected mothers.

DESIGN

The European Collaborative Study followed 1663 uninfected children from birth until at least 8 years of age using a standard protocol.

METHODS

Smoothers (running medians) illustrated patterns of immune markers over age by ART exposure and race. Associations between lymphocyte parameters and maternal/infant characteristics were quantified in linear regression analyses using z-scores obtained after modelling log10-transformed TLC, CD4 and CD8 cell counts using the LMS method. Cox proportional hazard models assessed time to TLC, CD4 and CD8 cell counts below the defined cut-off. Covariates included prematurity, gender, race, drug withdrawal and ART exposure.

RESULTS

Overall, black children had lower TLC, CD4 and CD8 cell counts than white children, and an increased risk of TLC, CD4 and CD8 cell counts below the cut-off. ART exposure was associated with TLC levels (but not with TLC below the cut-off for lymphopenia), with reduced CD4 cell counts in the first year of life, and with reduced CD8 cell counts until at least 8 years of age. Duration and intensity of ART exposure was associated with TLC levels.

CONCLUSION

The effect of ART exposure in fetal and early life on TLC and CD8 cell counts was prolonged until at least 8 years. These results add to the growing list of adverse effects associated with ART used as prevention of mother-to-child transmission of HIV.

Ex vivo zidovudine (AZT) treatment of CD34+ bone marrow progenitors causes decreased steady state mitochondrial DNA (mtDNA) and increased lactate production

Haematopoietic suppression is one of the dose-limiting side effects of chronic zidovudine (AZT) therapy. We tested the hypothesis that AZT would reduce mitochondrial DNA (mtDNA) content in haematopoietic progenitors causing impaired haematopoiesis and mitochondrial dysfunction. We studied the effects of AZT 0-50 microM in vitro, on normal human CD34+ haematopoietic progenitor cells cultured ex vivo for up to 12 days. The mean AZT IC50 for granulocyte (phenotype CD15+/CD14-) and erythroid (phenotype glycophorin+/CD45-) cell proliferation was 2.5 microM (SD+/-0.7) and 0.023 microM (SD+/-0.005), respectively. In myeloid-rich cell cultures, the mean lactate content of the media, compared to untreated controls, increased by 86% (SD+/-23) at 10 microM AZT and in erythroid-rich cultures it increased by 134% (SD+/-24) in the presence of 0.5 microM AZT. In myeloid-rich cultures the AZT IC50 for the reduction in the mitochondrial/nuclear DNA content ratio was 5.6 microM, whereas in erythroid rich cultures this AZT IC50 was < 0.0005 microM. AZT produced concentration-dependent inhibition of CD34+ progenitor proliferation into both myeloid and erythroid lineages; erythropoiesis was more sensitive than myelopoiesis. Concurrently, AZT reduced steady state mtDNA content, while increasing lactate production. These findings support the hypothesis that mtDNA is one of the intracellular targets involved in the pathogenesis of AZT-associated bone marrow progenitor cell toxicity.

Levels and patterns of neutrophil cell counts over the first 8 years of life in children of HIV-1-infected mothers

BACKGROUND

Antiretroviral drugs (ARV) as prophylaxis to prevent mother-to-child transmission of HIV results in decreased haematological parameters during and shortly after exposure, with recent data suggesting a more prolonged inhibition of haematopoiesis until at least 18 months.

DESIGN

Data on 156 HIV-infected and 1533 uninfected children in the European Collaborative Study followed from birth until at least 8 years of age.

METHODS

Smoothers and splines were used to elucidate patterns over age; linear mixed effects allowed for repeated measurements. Covariates included the child's HIV-1 infection status, prematurity, gender, race, drug withdrawal symptoms at birth and ARV exposure; effects on neutrophil count were quantified in regression analyses using z-scores (SD from mean) of neutrophil counts obtained after modelling untransformed values using the LMS method. For HIV-infected children, progression to AIDS and ARV therapy were also included.

RESULTS

After approximately 4 months of age, neutrophil counts were consistently and substantially lower in HIV-infected children than in uninfected children; in both groups, black children had significantly lower counts than white children across the whole age range. In uninfected children, male gender and ARV exposure were associated with reduced neutrophil count until at least 8 years of age. In HIV-infected children, advanced disease and ARV treatment were significantly associated with neutrophil count.

CONCLUSION

A considerably longer effect of exposure to ARV was shown in uninfected children than previously thought and significant associations were shown between race and gender and neutrophil count, as previously observed for lymphocyte counts. The clinical relevance of these reduced levels of neutrophils requires further investigation.

Azidothymidine promotes free radical generation by activated macrophages and hydrogen peroxide-iron-mediated oxidation in a cell-free system

Azidothymidine (AZT) and AZT monophosphate (AZT-MP) in concentrations as low as 10 and 50 microM, respectively, promote oxidation of chemically deacetylated 2',7'-dichlorodihydrofluorescein (DCDHF) to 2',7'-dichlorofluorescein (DCF) by rat peritoneal macrophages activated with latex. Cells were incubated with AZT and AZT-MP for 18 h, washed out from residual AZT or AZT-MP and activated with latex for 30 or 60 min in the presence of DCDHF. Latex-activated cells oxidize DCDHF extracellularly due to release of hydrogen peroxide and low-molecular iron complexes, which is verified using catalase, desferal and the peroxidase inhibitor sodium azide. AZT and AZT-MP increase DCDHF oxidation due to additional release of hydrogen peroxide as demonstrated by catalase inhibition of DCDHF oxidation and direct H(2)O(2) measurement. Thymidine and thymidine phosphates did not show any effect on macrophage activation. In separate experiments we evaluated the in vitro prooxidant activity of AZT, AZT-MP, AZT triphosphate (AZT-TP), AZT glucuronide (GAZT) and 3'-amino-3'-deoxythymidine (AMT) in a cell-free system using the hydrogen peroxide-iron-mediated oxidation of DCDHF. Under these conditions, AZT and AZT phosphates exhibit a prooxidant effect in concentrations as low as 100 microM. Furthermore, GAZT is a less effective prooxidant and AMT acts like an antioxidant. Thymidine did not show any effect.

Anemia in HIV infection: clinical impact and evidence-based management strategies

Anemia in human immunodeficiency virus (HIV)-infected patients can have serious implications, which vary from functional and quality-of-life decrements to an association with disease progression and decreased survival. In 2002, 16 members of the Anemia in HIV Working Group, an expert panel of physicians involved in the care of HIV-infected patients that met first in 1998, reconvened to assess new data and to translate these data into evidence-based treatment guidelines. The group reached consensus on the prevalence of anemia in the highly active antiretroviral therapy era; the risk factors that are independently associated with the development of anemia; the impact of anemia on quality of life, physical functioning, and survival; the impact of the treatment of hepatitis C virus coinfection on anemia in HIV-infected patients; evidence-based guidelines for treatment of anemia in HIV-infected patients, including the therapeutic role of epoetin alfa; and directions for future research.

Human Immunodeficiency Virus Hematology

The advent of potent antiretroviral therapy has altered the expected natural history of human immunodeficiency virus (HIV) infection and of many previously associated opportunistic complications, including malignancies. At the same time, HIV suppression hasn’t affected all of these complications equally and the longer expected survival of infected patients may allow the development of newer complications. Additionally, the use of potent antiretroviral combination therapy may itself lead to hematological toxicities. Together these changes affect the consultation role of the hematology-oncology specialist in comprehensive HIV care and demand ongoing education.

In Section I, Dr. Paul Volberding reviews the biology of antiretroviral drug development and the progression in discovering new agents as the viral life cycle is further elucidated. He briefly summarizes the process of combining agents to achieve the degree of viral suppression required for long-term clinical benefit.

In Section II, Dr. Kelty Baker reviews the effects of HIV and its therapy on hematologic dyscrasia and clotting disorders. She summarizes how therapy may decrease certain previously common manifestations of HIV disease while adding new problems likely to result in referral to the hematologist. In addition, she addresses the role of secondary infections, such as parvovirus, in this spectrum of disorders.

In Section III, Dr. Alexandra Levine discusses the still challenging aspects of HIV associated non-Hodgkin’s lymphoma and the association between HIV infection and Hodgkin’s disease. She addresses current controversies in the pathogenesis of HIV related lymphomas and summarizes a number of recent trials of combination chemotherapy, with or without monoclonal antibodies, in their management. Additionally, she reviews the complex relationship of HIV disease with multicentric Castleman’s disease and recent attempts to manage this disorder.

Potassium oxonate modulation of 5-fluorouracil-induced myelotoxicity in murine and human colony forming assays of hematopoietic precursor cells

Potassium oxonate (Oxo) is one of three components of S-1, an anticancer drug developed to improve the selective toxicity of 5-fluorouracil (5-FU). Oxo has been shown to reduce gastrointestinal toxicity. In this study, using murine and human granulocyte/macrophage colony forming (mCFU-GM, hCFU-GM) assays, we investigated whether Oxo can reduce 5-FU-induced myelotoxicity. The respective concentrations of 5-FU for 50% reduction (IC(50)) in mCFU-GM and hCFU-GM assays were 1.1 and 0.76 microM. The concentration-response curve was substantially steeper in the mCFU-GM assay than in the hCFU-GM assay. In the mCFU-GM assay, Oxo prevented growth suppression by 1 and 2 microM 5-FU, and at greater than 1 microM, it prevented suppression by 1 microM 5-FU almost completely. In the hCFU-GM assay, in contrast, Oxo prevented 5-FU suppression only slightly, and without a dose-response relationship. The difference between the mCFU-GM and hCFU-GM results may have stemmed from the spontaneous decomposition of Oxo during the longer culture period and Oxo's toxicity for human cells. Considering the human pharmacokinetic data, we concluded that Oxo has the potential to reduce 5-FU-induced myelotoxicity in human.

Tenofovir exhibits low cytotoxicity in various human cell types: comparison with other nucleoside reverse transcriptase inhibitors

Clinical studies with tenofovir disoproxil fumarate, an oral prodrug of the nucleotide analog tenofovir, recently approved for the treatment of HIV, have demonstrated antiviral activity and good tolerability in HIV-infected patients. In order to better understand the cytotoxicity profile of tenofovir relative to the other nucleoside reverse transcriptase inhibitors (NRTIs), the in vitro effects of these agents were evaluated in various human cell types. Tenofovir inhibited the proliferation of liver-derived HepG2 cells and normal skeletal muscle cells with CC(50) values of 398 and 870 microM, respectively. In comparison, ZDV, ddC, ddI, d4T, and abacavir all showed lower CC(50) values in these two cell types. Evaluation of hematopoietic toxicity revealed that tenofovir was less cytotoxic towards erythroid progenitor cells (CC(50)>200 microM) than ZDV, d4T, and ddC (CC(50)=0.06-5 microM). Despite some degree of donor-to-donor variability, the inhibitory activity of the tested NRTIs against myeloid cell lineage, in the order of decreasing severity, was consistently ddC>ZDV>d4T>tenofovir>3TC. Finally, tenofovir showed substantially weaker effects on proliferation and viability of renal proximal tubule epithelial cells than cidofovir, a related nucleotide analog with the potential to induce renal tubular dysfunction. In conclusion, tenofovir exhibited weak cytotoxic effects in all cell types tested with less in vitro cytotoxicity than the majority of NRTIs currently used for the treatment of HIV disease.

Comparison of in vitro drug-sensitivity of human granulocyte-macrophage progenitors from two different origins: umbilical cord blood and bone marrow

Predictive in vitro hematotoxicity assays using human cells will provide estimation of tolerable level and aid considerably the development of agents with greater therapeutic activity and less toxicity. Human hematopoietic cells can be derived from three sources: human bone marrow by sternal or femoral aspiration, mobilized peripheral blood, or umbilical cord blood samples collected from placentas after deliveries. Because of the difficulties to have a continuous supply of bone marrow cells from normal human donors and the related ethical problems, we performed a study to compare the sensitivity of human bone marrow cells (h-BMC) and human cord blood cells (h-CBC) to chemicals in order to confirm if h-CBC can readily replace bone marrow cells in checking the sensitivity of GM-CFU progenitors to drugs as preliminarily reported in literature. Our results showed that the prediction of IC50 values in human model is quite similar by using h-BMC or h-CBC. On the contrary, the type of medium influenced in a significant way the ICs determination of some drugs.

Diversity analysis of 14 156 molecules tested by the National Cancer Institute for anti-HIV activity using the quantitative structure-activity relational expert system MCASE

Using the MCASE program, a procedure to analyze the diversity of the large amount of available HIV-1 antiviral data was proposed. A subset of 1 819 chemicals was logically selected from the original 14 156 chemicals tested by NCI. This subset of chemicals was shown to contain most of the structural and the functional information of the original database. A full analysis of the 1 819 chemicals by the MCASE program produced a correlation between chemical structures and HIV antiviral activity. In our model, 74 fragments were identified as being responsible for all the chemical's HIV antiviral activity. These fragments may be related to different inhibiting mechanisms, some known and some probably still unknown. The expert system resulting from this analysis can be used to predict the activity of new chemicals and to design new agents that can target multiple enzymes. This was shown to be the case by using the model to predict the activity of 10 diverse chemicals whose activities were not known at the time of model development. Of these, 8 were predicted in agreement with experimental observations. As far as we can tell, this is probably the first project ever to attempt to create a quantitative model of activity for such a massive database of diverse chemicals.

Alternative testing systems for evaluating noncarcinogenic, hematologic toxicity

Hematopoietic tissues are the targets of numerous xenobiotics. Clinical hematotoxicity is either a decrease or an increase in peripheral blood cell counts in one or more cell lineages--a cytopenia or a cytosis, respectively--that carries a risk of an adverse clinical event. The purpose of in vitro hematotoxicology is the prediction of these adverse hematologic effects from the effects of the toxicants on human hematopoietic targets under controlled experimental conditions in the laboratory. Building on its important foundations in experimental hematology and the wealth of hematotoxicology data found in experimental oncology, this field of alternative toxicology has developed rapidly during the past decade. Although the colony-forming unit-granulocyte/monocyte neutrophil progenitor is most frequently evaluated, other defined progenitors and stem cells as well as cell types found in the marrow stroma can be evaluated in vitro. End points have been proposed for predicting toxicant exposure levels at the maximum tolerated dose and the no observable adverse effect level for the neutrophil lineage, and several clinical prediction models for neutropenia have developed to the point that they are ready for prospective evaluation and validation in both preclinical species and humans. Known predictive end points are the key to successful comparisons across species or across chemical structures when in vitro dose-response curves are nonparallel. Analytical chemistry support is critical for accurate interpretation of in vitro data and for relating the in vitro pharmacodynamics to the in vivo pharmacokinetics. In contrast to acute neutropenia, anemia and acute thrombocytopenia, as well as adverse effects from chronic toxicant exposure, are much more difficult to predict from in vitro data. Pharmacologic principles critical for clinical predictions from in vitro data very likely will apply to toxicities to other proliferative tissues, such as mucositis.

The human immunodeficiency virus type 1 Tat protein potentiates zidovudine-induced cellular toxicity in transgenic mice

3'-Azido-2',3'-dideoxythymidine (AZT, zidovudine) is the principal antiretroviral agent in the treatment of AIDS. Although beneficial, AZT remains restricted for human usage because of its severe toxic effects. We examined the AZT sensitivity in transgenic mice expressing HIV-1 one-exon-encoded 72 amino acid Tat (Tat72) and full-length 86 amino acid Tat (Tat86) proteins. Administration of AZT (1 mg/ml) in drinking water for 1 week resulted in a three- to fourfold decrease in hematopoietic progenitors from bone marrow in Tat mice compared to AZT-treated nontransgenic controls as determined by erythroid and granulocyte/macrophage colony-forming unit assays. In liver and thymus, two of the tissues examined, AZT treatment of Tat mice resulted in as much as 80-90% suppression of Mn-superoxide dismutase (Mn-SOD) activity. Other parameters associated with loss of Mn-SOD such as increase in carbonyl proteins and decrease of sulfhydryl content were also significantly enhanced by AZT in Tat mice. Our in vivo study suggests that AZT therapy is associated with oxidative damage affecting cellular functions in several tissues and that Tat is one of the contributory factors in AZT-induced toxicities. The findings of AZT-induced oxidative damage may help to improve the therapeutic index of AZT and other related drugs in AIDS patients.

Hematologic complications of human immunodeficiency virus infection and the acquired immunodeficiency syndrome

The hematologic manifestations of HIV infection and AIDS are common and may cause symptoms that are life-threatening and impair the quality of life of these patients. The most important of these manifestations are cytopenias. Anemia and neutropenia are generally caused by inadequate production because of suppression of the bone marrow by the HIV infection through abnormal cytokine expression and alteration of the bone marrow microenvironment. Thrombocytopenia is caused by immune-mediated destruction of the platelets, in addition to inadequate platelet production. The incidence and severity of cytopenia are generally correlated to the stage of the HIV infection. Other causes of cytopenia in these patients include adverse effects of drug therapy, the secondary effects of opportunistic infections or malignancies, or other preexisting or coexisting medical problems that may be prevalent in the HIV-infected population. Diagnosis of the mechanism and cause of the cytopenia may allow for specific management. Optimal management of the underlying HIV infection is essential, and mild cytopenia in asymptomatic patients may need no specific management. Supportive care for anemia includes the use of erythropoietin in addition to the judicious use of red blood cell transfusions. Therapy for neutropenia includes the use of the myeloid growth factors G-CSF and GM-CSF. Immune-mediated thrombocytopenia may be treated with a combination of zidovudine, corticosteroids, IVGG, and splenectomy. Platelet transfusions are sometimes needed for the treatment of thrombocytopenia caused by decreased production. Other hematologic manifestations such as hypergammaglobulinemia and lupus anticoagulants are commonly asymptomatic and usually require no specific therapy, but they can rarely cause morbidity and require specific interventions.

Selective protection of toxicity of 2',3'-dideoxypyrimidine nucleoside analogs by beta-D-uridine in human granulocyte-macrophage progenitor cells

beta-D-Uridine protected human granulocyte-macrophage lineage cells in both semi-solid (granulocyte-macrophage colony-forming units, CFU-GM) and liquid cultures against the toxic effects of 3'-azido-3'-deoxythymidine (AZT), 3'-fluoro-3'-deoxythymidine (FLT) and a combination of AZT and FLT, without impairment of the activities of these respective drugs against human immunodeficiency virus (HIV) replication. In addition, beta-D-uridine also protected human CFU-GM against toxicity of the in vivo AZT metabolite, 3'-amino-3'-deoxythymidine (AMT). Beta-L-uridine and alpha-D-uridine, two stereoisomers of the natural form, and the base uracil, were unable to protect cells against either AZT or FLT toxicity, whereas beta-D-uridine-5'-bis(SATE)phosphotriester, a prodrug of beta-D-uridine-5'-monophosphate, successfully protected cells against AZT toxic effects, suggesting that beta-D-uridine needs to be metabolized to its nucleotides to exert a pharmacological effect. These data suggest in addition that AZT, FLT and AMT share a common target site(s) of toxicity involved in myelosuppression.

Comparative pharmacokinetics of zidovudine and its toxic catabolite 3'-amino-3'-deoxythymidine in HIV-infected patients

The plasma pharmacokinetics of zidovudine (ZDV, 3'-azido-3'-deoxythymidine) and its toxic catabolite 3'-amino-3'-deoxythymidine (AMT) was investigated in six HIV-infected patients receiving 100 or 500 mg of ZDV by oral administration. Zidovudine plasma pharmacokinetic parameters were in good agreement with previously reported data with a total plasma clearance (Cl) of 2.33 and 2.49 liters/hr/kg and an apparent elimination t1/2 of 1.14 and 1.20 hr at 100- and 500-mg doses, respectively. 3'-Amino-3'-deoxythymidine was detectable in the plasma of all patients, with maximum plasma levels (Cmax) being reached within 2 hr post-dosing. No dose relationship in the formation of AMT expressed as the area under the plasma level-time curve (AUC) was established within the studied dose range of ZDV. The AUCAMT was 145.4 and 92.4 ng/ml.hr after administration of 100 and 500 mg of ZDV, respectively. These results reflect an unexpectedly large interindividual variation in the formation of AMT. The lack of linearity in AMT pharmacokinetics prevents the prediction of its plasma levels based only on the administered oral dose of ZDV.

A cellular model for drug interactions on hematopoiesis: the use of human umbilical cord blood progenitors as a model for the study of drug-related myelosuppression of normal hematopoiesis

A cellular model of hematopoiesis which would be more convenient than bone marrow (BM) progenitors and directly relevant to human pathology is needed in order to investigate xenobiotic toxicity. Human umbilical cord blood (HCB), previously shown to be able to repopulate BM, provides a powerful in vitro model of normal human hematopoiesis. In order to validate the use of normal HCB progenitors as targets for dose-related myelosuppression, we used clonogenic assays and expansion in a liquid culture of progenitor-enriched cell suspensions from HCB. A series of 8 reference molecules, doxorubicin, cytosine-arabinoside, 5-fluorouracil, 3'-azido-3'-deoxythymidine, acetylsalicylic acid, sodium valproate and two cephalosporin antibiotics, were tested. In vitro 50% inhibition concentrations (IC50) were compared to those observed or reported with BM progenitors, and to the values of plasma concentrations from treated patients. HCB progenitors as in vitro targets for cytotoxic molecules were easy to access and handle, and their use was sensitive, specific and reproducible. They gave results similar to BM progenitors and allowed a qualitative approach to cellular metabolism and toxicity using morphological, flow cytometric and chromatographic methods.

Effect of combination interleukin-3 (IL-3) and granulocyte-macrophage colony stimulating factor (GM-CSF) on hematopoiesis administered to retrovirus-infected immunodeficient mice receiving dose-escalation zidovudine (AZT)

We have previously demonstrated that continuous administration of dose-escalation zidovudine (AZT) in either normal or LP-BM5 MuLV immunodeficient virus-infected mice (MAIDS) was associated with the development of anemia, neutropenia, and thrombocytopenia. Hematopoietic growth factors/cytokines are being evaluated to determine their efficacy in ameliorating the hematopoietic toxicity associated with AZT. In normal mice receiving AZT, an increase in only plasma erythropoietin and not GM-CSF, Meg-CSF or TNF-alpha has been reported. This article describes studies that investigated the effect of combination interleukin-3 (IL-3) and granulocyte-macrophage colony stimulating factor (GM-CSF) administered in normal non-viral, viral-infected, and viral-infected C57BL6 mice receiving dose-escalation AZT, i.e. 0.1 mg/ml, 1.0 mg/ml, and 2.5 mg/ml placed in the drinking water. Non-viral control mice responded to IL-3/GM-CSF by increasing erythropoiesis, myelopoiesis and platelet production measured by increased bone marrow and spleen derived erythroid, myeloid and platelet precursor stem cells cultured in semi-solid media. Virus-infected control mice not receiving IL-3/GM-CSF developed pancytopenia. Administration of IL-3/GM-CSF to virus-infected mice receiving dose-escalation AZT did not ameliorate the peripheral pancytopenia associated with immunodeficiency disease and AZT treatment, even though erythroid, myeloid and platelet precursor progenitor cells were increased at certain times when compared to either normal or viral-infected mice receiving IL-3/GM-CSF. These results indicate that the combination use of IL-3 and GM-CSF in vivo is only a partially effective growth factor/cytokine treatment to ameliorate the hematopoietic toxicity associated with the use of the anti-viral drug zidovudine.

The CD4 receptor plays essential but distinct roles in HIV-1 infection and induction of apoptosis in primary bone marrow GPIIb/IIIa+ megakaryocytes and the HEL cell line

We investigated whether cells belonging to the megakaryocytic lineage could be infected in vitro with human immunodeficiency virus type-1 (HIV-1). Primary GPIIb/IIIa+ bone marrow (BM) cells and HEL continuous cell line were first phenotypically characterized for the presence of megakaryocytic markers and CD4 antigen, then challenged in vitro with the laboratory strain IIIB of HIV-1. Both GPIIb/IIIa+ BM and HEL cells expressed significant levels of CD4 receptor (> 50%) and were efficiently infected with HIV-1, as judged by the presence of proviral DNA after polymerase chain reaction analysis and by quantitative evaluation of gag p24 antigen in the culture supernatants. Of note, infection with HIV-1 in both primary BM megakaryocytes and HEL cells was specifically blocked by soluble recombinant CD4. To ascertain whether the CD4 receptor was essential for infection of megakaryocytic cells, HEL were subcloned into CD4+ and CD4- cells. Although unfractionated and CD4+ HEL cells were productively infected with HIV-1, CD4- HEL cells could not be infected. Infection of HEL cells did not induce gross cytotoxic effects or a significant increase of apoptosis. On the other hand, treatment of unfractionated or CD4+ HEL cells with cross-linked recombinant env gp120 or Leu3a anti-CD4 monoclonal antibody markedly (P < 0.01) increased the degree of apoptosis with respect to HEL cells infected with HIV-1 or treated with cross-linked gag p24 or anti-GPIIb/IIIa antibody. Taken together, these data indicate that the CD4 receptor represents the main route of infection in cells belonging to the megakaryocytic lineage. Moreover, an inappropriate engagement of CD4 by either free env gp120 or anti-CD4 monoclonal antibody could be more relevant than a direct infection with HIV-1 in the induction of the frequent BM megakaryocyte abnormalities found in HIV-1 seropositive thrombocytopenic patients.

Modified antisense oligodeoxynucleotides against the splice acceptor site of tat do not inhibit in vitro hematopoietic colony growth in HIV-positive patients

The hematopoietic failure in the majority of patients with progressive HIV infection is further aggravated by virustatic agents like azidothymidine. As an alternative therapeutic attempt, three derivatives of an antisense oligodeoxynucleotide (ODN) against the splice acceptor site of the tat gene have been shown to inhibit HIV replication in vitro. This study was aimed at examining whether these agents are toxic to the hematopoietic progenitor cells. To this end, bone marrow cells from HIV-positive and healthy persons were depleted from adherent cells to eliminate fibroblasts. In further experiments, the cells were additionally enriched for CD34-positive hematopoietic progenitor cells or were depleted from delta TCS-1-positive T lymphocytes. At concentrations of 1.25-10 microM, the three antisense ODN did not inhibit any erythrocyte or granulocyte-monocyte colony growth from CD34-positive cells, either from the HIV-positive or from the HIV-negative cohort. In contrast to azidothymidine, which served as inhibitory control, a significant increase of colony growth was seen after depletion of fibroblasts, of delta TCS-1-positive cells, or without cell separation. In conclusion, the three oligodeoxynucleotides do not exert any hematotoxic effect but do increase colony formation from low-density bone marrow cells in vitro and could therefore be useful in future clinical studies.