3'-Azido-3'-deoxythymidine inhibits erythroid-specific transcription factors in human erythroid K562 leukemia cells

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.

Pharmacology of current and promising nucleosides for the treatment of human immunodeficiency viruses

Nucleoside antiretroviral agents are chiral small molecules that have distinct advantages compared to other classes including long intracellular half-lives, low protein binding, sustained antiviral response when a dose is missed, and ease of chemical manufacture. They mimic natural nucleosides and target a unique but complex viral polymerase that is essential for viral replication. They remain the cornerstone of highly active antiretroviral therapy (HAART) and are usually combined with non-nucleoside reverse [corrected] transcriptase and protease inhibitors to provide powerful antiviral responses to prevent or delay the emergence of drug-resistant human immunodeficiency virus (HIV). The pharmacological and virological properties of a selected group of nucleoside analogs are described. Some of the newer nucleoside analogs have a high genetic barrier to resistance development. The lessons learned are that each nucleoside analog should be treated as a unique molecule since any structural modification, including a change in the enantiomeric form, can affect metabolism, pharmacokinetics, efficacy, toxicity and resistance profile.

Proteins pattern alteration in AZT-treated K562 cells detected by two-dimensional gel electrophoresis and peptide mass fingerprinting

In this study we report the effect of AZT on the whole protein expression profile both in the control and the AZT-treated K562 cells, evidenced by two-dimensional gel electrophoresis and peptide mass fingerprinting analysis. Two-dimensional gels computer digital image analysis showed two spots that appeared up-regulated in AZT-treated cells and one spot present only in the drug exposed samples. Upon extraction and analysis by peptide mass fingerprinting, the first two spots were identified as PDI-A3 and stathmin, while the third one was proved to be NDPK-A. Conversely, two protein spots were present only in the untreated K562 cells, and were identified as SOD1 and HSP-60, respectively.

[Mitochondrial cytopathies associated with HIV infection]

The tremendous progress achieved during the last few years with the use of highly active antiretroviral therapy in suppressing HIV replication together with improvements in immunity have been tempered by a growing number of new adverse effects. Mitochondrial toxicity is one aspect of these long-term toxicities of antiretroviral drugs, with the role of nucleoside analogs particularly underlined. Some cases of impaired mitochondrial function have been clearly identified, such as pancreatitis due to didanosine, neuropathy due to zalcitabine, myopathy due to zidovudine, and lactic acidosis due to stavudine. These mitochondrial toxicities can affect several organs, presenting different patterns of symptoms: from asymptomatic to states with few symptoms despite huge metabolic abnormalities whose prognosis is immediately life-threatening. Beyond the inhibition of DNA polymerase gamma using nucleoside analogs, responsible for decreasing mitochondrial DNA in certain targeted organs, it appears that several physiopathologic mechanisms interact to explain this observed toxicity, HIV itself plays a role, and the underlying genetic pool needs to be better identified. Such cases mean that, it is imperative to avoid cumulated toxicities caused by associated treatments. With serious cases, or persistent symptoms despite discontinuing the nucleoside analogs responsible for such toxicity, one must propose vitamins, mitochondrial co-factors, or anti-oxidants. However, the future lies in the use of potent, less toxic nucleoside analogs, and in developing compounds belonging to other classes of antiretrovirals.

Inhibition of beta-globin gene expression by 3'-azido-3'-deoxythymidine in human erythroid progenitor cells

3'-Azido-3'-deoxythymidine (AZT) treatment in HIV-infected patients is limited by bone marrow suppression including neutropenia and anemia. Previous studies had shown a direct effect of high concentrations of this drug on globin gene expression in K-562 erythroleukemia cells. To better define the mechanism(s) of AZT-induced bone marrow toxicity, the present study evaluates these effects in more relevant human erythroid progenitor liquid cultures, because AZT is 100 times more toxic to human bone marrow cells than K-562 cells. At a clinically relevant concentration of 1 microM, AZT inhibited specifically erythroid cell growth by approximately 58% as compared with untreated cells. The percentage of cells synthesizing hemoglobin was decreased also by 47% in AZT-treated cells with beta-globin mRNA levels accounting for 0.27 pmol in treated cells as compared with 1.44 under control conditions while beta-actin levels remained unchanged. Under the same conditions, AZT inhibited the beta-globin chain synthesis by approximately 60% as compared with the control. Consistent with the data described above was the finding that a concentration as low as 0.1 microM of AZT decreased by almost 40% the binding level of the erythroid-specific transcription factor GATA-1. These findings demonstrate that AZT, at clinical relevant concentrations, specifically inhibits beta-globin gene expression in human erythroid progenitor liquid cell culture.