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

Advanced in immunological monitoring of HIV infection: profile of immune cells and cytokines in people living with HIV-1 in Benin

BACKGROUND

Immune cells and cytokines have been linked to viremia dynamic and immune status during HIV infection. They may serve as useful biomarkers in the monitoring of people living with HIV-1 (PLHIV-1). The present work was aimed to assess whether cytokines and immune cell profiles may help in the therapeutic follow-up of PLHIV-1.

METHODS

Forty PLHIV-1 in treatment success (PLHIV-1s) and fifty PLHIV-1 in treatment failure (PLHIV-1f) followed at the University Hospital of Abomey-Calavi/Sô-Ava in Benin were enrolled. Twenty healthy persons were also recruited as control group. Circulating cytokines and immune cells were quantified respectively by ELISA and flow cytometry.

RESULTS

PLHIV-1 exhibited low proportions of CD4 + T cells, NK, NKT, granulocytes, classical and non-classical monocytes, and high proportions of CD8 + T cells, particularly in the PLHIV-1f group, compared to control subjects. Eosinophils, neutrophils and B cell frequencies did not change between the study groups. Circulating IFN-γ decreased whereas IL-4 significantly increased in PLHIV-1s compared to PLHIV-1f and control subjects even though the HIV infection in PLHIV-1s downregulated the high Th1 phenotype observed in control subjects. However, Th1/Th2 ratio remained biased to a Th1 phenotype in PLHIV-1f, suggesting that high viral load may have maintained a potential pro-inflammatory status in these patients. Data on inflammatory cytokines showed that IL-6 and TNF-α concentrations were significantly higher in PLHIV-1s and PLHIV-1f groups than in control subjects. Significant high levels of IL-5 and IL-7 were observed in PLHIV-1f compared to controls whereas PLHIV-1s presented only a high level of IL-5. No change was observed in IL-13 levels between the study groups.

CONCLUSION

Our study shows that, in addition to CD4/CD8 T cell ratio, NK and NKT cells along with IL-6, TNF-α, IL-5 and IL-7 cytokines could serve as valuable immunological biomarkers in the therapeutic monitoring of PLHIV-1 although a larger number of patients would be necessary to confirm these results.

The stage-specific impairment of granulopoiesis in people living with HIV/AIDS (PLWHA) with neutropenia

Neutropenia and impaired functions were common manifestation in antiretroviral therapy (ART) in both naïve and experienced PLWHA. Granulopoiesis can be divided into two phases: lineage determination and committed granulopoiesis. However, stage-specific impairment of granulopoiesis in PLWHA with neutropenia remains unclear. A total of 48 ART-naïve and 49 ART-experienced PLWHA from 2016 to 2018 were recruited and divided into non-, mild-, and moderate-to-severe-neutropenia groups according to their neutrophil counts. The bone marrow aspirates and peripheral blood were collected and analyzed by multicolor flow cytometry for granulocyte subsets, hematopoietic stem/progenitor cells (HSPC), apoptosis, and emigration and retention of different subsets. Compared with healthy donors, the percentages of circulating segmented neutrophils were significantly decreased along with an increase of immature neutrophils in both groups. ART-naïve patients with moderate to severe neutropenia exhibited decreased proportion and accelerated apoptosis of relative mature segmented neutrophils. In contrast, ART-experienced patients with neutropenia displayed decreased proportion of granulocyte macrophage progenitors, indicating a defect at a stage of lineage determination. Meanwhile, ART-experienced patients with neutropenia also the expression of CXCR4 segmented neutrophils, suggesting an increased retention of segmented neutrophils inn the bone marrow. ART-naïve patients with neutropenia is caused by increased apoptosis of relatively differentiated neutrophils at committed granulopoiesis, whereas impaired lineage determination and enhanced retention of segmented neutrophils contribute to in ART-experienced patients.

Safety of tenofovir during pregnancy: early growth outcomes and hematologic side effects in HIV-exposed uninfected infants

Intrauterine exposure to zidovudine-based combination antiretroviral therapy (cART) can cause severe anemia within the first weeks of life. Tenofovir disoproxil fumarate (TDF)-based regimens may have less hematologic side effects but may affect growth parameters. This study aimed to assess the safety of TDF for prevention of mother-to-child transmission (PMTCT) in HIV-exposed uninfected infants regarding early growth outcomes and hematologic side effects. Our retrospective observational cohort study included children born (n = 232) to HIV-infected mothers (n = 228) on cART. Blood counts were compared at birth, 4-6 weeks, and 3, 12 and 18 months of age. Growth parameters were measured at birth and 12 and 18 months of age. Data were analyzed according to treatment group (TDF and non-TDF cART regimes). The median hemoglobin (Hgb) was significantly lower in the non-TDF-based group at birth (15.4 g/dl vs. 16.9 g/dl; **p = 0.002) and at 4-6 weeks of age (9.9 g/dl vs. 10.4 g/dl; **p = 0.004). The mean corpuscular volume was higher in the non-TDF-based group (109 fl vs. 105 fl; ***p < 0.001) as well at 4-6 weeks (102 fl vs. 95 fl; ***p < 0.001). In the TDF-based group, a higher proportion of neutropenia (grade 2 and higher) compared to the non-TDF-group (21.4% vs. 11%; *p = 0.015) was observed at three months of age. This effect was transient. There was no difference in growth.Conclusions: TDF appears to have no major side effects in our cohort. Transient anemia was observed more commonly with non-TDF regimens. However, our research suggests a potential delayed effect of TDF on neutrophils at 3 months of age.What is Known:• TDF is suspected to affect the growth of HIV-exposed uninfected infants.• Non-TDF-based cART regimes for prevention of mother-to-child transmission of HIV often result in transient anemia in the infant.What is New:• TDF appears to have no major side effects regarding the growth of HIV-exposed uninfected infants.• Our research suggests a potential delayed effect of TDF on neutrophils at 3 months of age in these infants.

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.

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.

Neurotoxic effects of AZT on developing and adult neurogenesis

Azidothymidine (AZT) is a synthetic, chain-terminating nucleoside analog used to treat HIV-1 infection. While AZT is not actively transported across the blood brain barrier, it does accumulate at high levels in cerebrospinal fluid, and subsequently diffuses into the overlying parenchyma. Due to the close anatomical proximity of the neurogenic niches to the ventricular system, we hypothesize that diffusion from CSF exposes neural stem/progenitor cells and their progeny to biologically relevant levels of AZT sufficient to perturb normal cell functions. We employed in vitro and in vivo models of mouse neurogenesis in order to assess the effects of AZT on developing and adult neurogenesis. Using in vitro assays we show that AZT reduces the population expansion potential of neural stem/progenitor cells by inducing senescence. Additionally, in a model of in vitro neurogenesis AZT severely attenuates neuroblast production. These effects are mirrored in vivo by clinically-relevant animal models. We show that in utero AZT exposure perturbs both population expansion and neurogenesis among neural stem/progenitor cells. Additionally, a short-term AZT regimen in adult mice suppresses subependymal zone neurogenesis. These data reveal novel negative effects of AZT on neural stem cell biology. Given that the sequelae of HIV infection often include neurologic deficits—subsumed under AIDS Dementia Complex (Brew, 1999)—it is important to determine to what extent AZT negatively affects neurological function in ways that contribute to, or exacerbate, ADC in order to avoid attributing iatrogenic drug effects to the underlying disease process, and thereby skewing the risk/benefit analysis of AZT therapy.

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?

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.

HIV and malaria co-infection: interactions and consequences of chemotherapy

The global epidemiology of HIV/AIDS and malaria overlap because a significant number of HIV-infected individuals live in regions with different levels of malaria transmission. Although the consequences of co-infection with HIV and malaria parasites are not fully understood, available evidence suggests that the infections act synergistically and together result in worse outcomes. The importance of understanding chemotherapeutic interactions during malaria and HIV co-infection is now being recognized. We know that some antimalarial drugs have weak antiretroviral effects; however, recent studies have also demonstrated that certain antiretroviral agents can inhibit malaria-parasite growth. Here, we discuss recent findings on the impact of HIV/AIDS and malaria co-infection and the possible roles of chemotherapy in improving the treatment of these diseases.

Vitamins C and E prevent AZT-induced leukopenia and loss of cellularity in bone marrow. Studies in mice

A major limitation in the use of AZT for AIDS treatment is the occurrence of side effects, such as leukopenia. The effects of antioxidant vitamins C and E on AZT-induced leukopenia were investigated in mice. Mice were divided into four groups: (1) controls; (2) AZT-treated; (3) treated with AZT plus vitamins C and E; and (4) pre-treated with vitamins and then treated with AZT plus vitamins. Our results demonstrate that AZT causes leukopenia in mice, which was abrogated by administration of vitamins C and E in the pre-treated group. These vitamins prevented the decrease in cellular content induced by AZT in bone marrow and diminished peroxide levels in myeloid precursors in bone marrow. AZT also caused an increase in plasma malondialdehyde and blood oxidized glutathione levels, which was prevented by the administration of antioxidant vitamins. In conclusion, oxidative stress is involved in AZT-induced leukopenia which may be prevented by antioxidant treatment.

Oxazolidinones inhibit cellular proliferation via inhibition of mitochondrial protein synthesis

The oxazolidinones are a relatively new structural class of antibacterial agents that act by inhibiting bacterial protein synthesis. The oxazolidinones inhibit mitochondrial protein synthesis, as shown by [35S]methionine incorporation into intact rat heart mitochondria. Treatment of K562 human erythroleukemia cells with the oxazolidinone eperezolid resulted in a time- and concentration-dependent inhibition of cell proliferation. The cells remained viable, but an increase in doubling time was observed with eperezolid treatment. Inhibition was reversible, since washing and refeeding of cells in the absence of compound resulted in a resumption of growth. The growth-inhibitory effect of the oxazolidinones did not appear to be cell type specific, and inhibition of CHO and HEK cells also was demonstrated. Treatment of cells resulted in a decrease in mitochondrial cytochrome oxidase subunit I levels, consistent with an inhibition of mitochondrial protein synthesis. Eperezolid caused no growth inhibition of rho zero (rho0) cells, which contain no mitochondrial DNA; however, the growth of the parent 143B cells was inhibited. These results provide a direct demonstration that the inhibitory effect of eperezolid in mammalian cells is the result of mitochondrial protein synthesis inhibition.