Relevance of experimental models for investigation of genotoxicity induced by antiretroviral therapy during human pregnancy

Risk of cancer in children exposed to antiretroviral nucleoside analogues in utero: The french experience

All nucleoside analogues for treating HIV infection, due to their capacity to integrate into and alter human DNA, are experimentally genotoxic to some extent. The long-term oncogenic risk after in utero exposure remains to be determined. Cancer incidence in uninfected children exposed to nucleos(t)ide reverse transcriptase inhibitors (NRTIs) was evaluated, by cross-checking against the National Cancer Registry, in the French perinatal study of children born to HIV⁺ mothers. Twenty-one cancers were identified in 15,163 children (median age: 9.9 years [interquartile range (IQR): 5.8-14.2]) exposed to at least one NRTI in utero between 1990 and 2014. Five of these children were exposed to zidovudine monotherapy, and 15 to various combinations, seven of which included didanosine. Overall, the total number of cases was not significantly different from that expected for the general population (SIR = 0.8[0.47-1.24]), but the number of cases after didanosine exposure was twice that expected (SIR = 2.5 [1.01-5.19]). Didanosine accounted for only 10% of prescriptions but was associated with one-third of cancers. In multivariate analysis, didanosine exposure was significantly associated with higher risk (HR = 3.0 [0.9-9.8]). This risk was specifically linked to first-trimester exposure (HR = 5.5 [2.1-14.4]). Three cases of pineoblastoma, a very rare cancer, were observed, whereas 0.03 were expected. Two were associated with didanosine exposure. Despite reassuring data overall, there is strong evidence to suggest that didanosine displays transplacental oncogenicity. These findings cannot be extrapolated to other NRTIs, but they highlight the need for comprehensive evaluations of the transplacental genotoxicity of this antiretroviral class. Environ. Mol. Mutagen., 60:404-409, 2019. © 2017 Wiley Periodicals, Inc.

Persistent metabolic changes in HIV-infected patients during the first year of combination antiretroviral therapy

The HIV-human metabolic relationship is a complex interaction convoluted even more by antiretroviral therapy (cART) and comorbidities. The ability of cART to undo the HIV induced metabolic dysregulation is unclear and under-investigated. Using targeted metabolomics and multiplex immune biomarker analysis, we characterized plasma samples obtained from 18 untreated HIV-1-infected adult patients and compared these to a non-HIV infected (n = 23) control population. The biogenic amine perturbations during an untreated HIV infection implicated altered tryptophan- nitrogen- and muscle metabolism. Furthermore, the lipid profiles of untreated patients were also significantly altered compared to controls. In untreated HIV infection, the sphingomyelins and phospholipids correlated negatively to markers of infection IP-10 and sIL-2R whereas a strong association was found between triglycerides and MCP-1. In a second cohort, we characterized plasma samples obtained from 28 HIV-1-infected adult patients before and 12 months after the start of cART, to investigate the immune-metabolic changes associated with cART. The identified altered immune-metabolic pathways of an untreated HIV infection showed minimal change after 12 months of cART. In conclusion, 12 months of cART impacts only mildly on the metabolic dysregulation underlying an untreated HIV infection and provide insights into the comorbidities present in virally suppressed HIV patients.

Associations of human gene EPB41L3 DNA methylation and cervical intraepithelial neoplasia in women living with HIV-1 in Africa

OBJECTIVES

To evaluate associations of DNA methylation of the human tumour suppressor gene EPB41L3 with high-grade cervical intraepithelial neoplasia (CIN2+) and HIV-related factors among women living with HIV-1 (WLHIV) in Burkina Faso and South Africa.

DESIGN

Case-control study of WLHIV aged 25-50 with histology-determined CIN2+ (cases, N = 152) and ≤CIN1 (controls, N = 210).

METHODS

EPB41L3 methylation was measured by pyrosequencing of bisulphite converted DNA from exfoliated cervical specimens at baseline and 16 months later. Median methylation levels were compared across CIN grades using the Mann-Whitney test and Cuzick test for trend. EPB41L3 methylation levels were dichotomized into 'high' and 'low' using the 66.7 percentile point of the distribution in the controls. Associations of EPB41L3 methylation with HIV-related factors were estimated by logistic regression.

RESULTS

Among 94 WLHIV in Burkina Faso and 268 in South Africa, median methylation levels at baseline for EPB41L3 increased with increasing CIN grade in both countries (P-trend <0.001).'High' methylation was more frequent among women with a longer time since HIV diagnosis in Burkina Faso [>5 years vs. ≤5 years; adjusted odds ratio (aOR) = 4.15, 95% CI 1.09-15.83, adjusted for age, CD4 count, high-risk HPV and CIN status], with low CD4 count in both countries (CD4 ≤200 vs. ≥350 cells/μl: aOR = 7.14, 95% CI 1.44-35.37 in Burkina Faso; aOR = 2.55, 95% CI 1.07-6.07 in South Africa), and with prolonged ART use in South Africa (ART >2 years vs. ART-naïve: aOR = 2.40, 95% CI: 1.23-4.69).

CONCLUSION

Methylation of EPB41L3 DNA is elevated among WLHIV with CIN2+ and independently associated with lower CD4 count and ART use.

Risk of cancer in children exposed to didanosine in utero

BACKGROUND

Evaluation of long-term tolerance to antiretroviral exposure during pregnancy is required. An increased risk of cancer has been suggested in children exposed in utero to didanosine.

METHODS

Updated evaluation of cancer incidence in uninfected children exposed to nucleos(t)ide reverse transcriptase inhibitors (NRTIs) in the French perinatal study of children born to HIV+ mothers, by cross-checking with the National Cancer Registry. Associations between cancer risk and exposure to NRTIs were evaluated by univariate survival analysis and Cox proportional hazard models. Standardized incidence ratios (SIR) were used for comparison with the general population.

RESULTS

A total of 21 cancers were identified in 15 163 children (median age: 9.9 years [interquartile range (IQR): 5.8-14.2]) exposed to at least one NRTI in utero, between 1990 and 2014. Five children were exposed to zidovudine monotherapy, and 16 to various combinations, seven including didanosine. Didanosine accounted for only 10% of prescriptions but was associated with one-third of cancers. In a multivariate analysis, didanosine exposure was significantly associated with higher risk [hazard ratio = 3.0 (0.9-9.8)]. The risk was specifically linked with first-trimester exposure [hazard ratio = 5.5 (2.1-14.4)]. Overall, the total number of cases was not significantly different from that expected for the general population [SIR = 0.8 (0.47-1.24)], but was twice that expected after didanosine exposure [SIR = 2.5 (1.01-5.19)].

CONCLUSION

There are strong arguments to suggest that didanosine displays transplacental oncogenicity. Although not extrapolable to other NRTIs, they stress the need for comprehensive evaluation of the transplacental genotoxicity of this antiretroviral class.

Population approach to analyze the pharmacokinetics of free and total lopinavir in HIV-infected pregnant women and consequences for dose adjustment

The aims of this study were to describe the unbound and total lopinavir (LPV) pharmacokinetics in pregnant women in order to evaluate if a dosing adjustment is necessary during pregnancy. Lopinavir placental transfer is described, and several genetic covariates were tested to explain its variability. A total of 400 maternal, 79 cord blood, and 48 amniotic fluid samples were collected from 208 women for LPV concentration determinations and pharmacokinetics analysis. Among the maternal LPV concentrations, 79 samples were also used to measure the unbound LPV concentrations. Population pharmacokinetics models were developed by using NONMEM software. Two models were developed to describe (i) unbound and total LPV pharmacokinetics and (ii) LPV placental transfer. The pharmacokinetics was best described by a one-compartment model with first-order absorption and elimination. A pregnancy effect was found on maternal clearance (39% increase), whereas the treatment group (monotherapy versus triple therapy) or the genetic polymorphisms did not explain the pharmacokinetics or placental transfer of LPV. Efficient unbound LPV concentrations in nonpregnant women were similar to those measured during the third trimester of pregnancy. Our study showed a 39% increase of maternal total LPV clearance during pregnancy, whereas unbound LPV concentrations were similar to those simulated in nonpregnant women. The genetic polymorphisms selected did not influence the LPV pharmacokinetics or placental transfer. Thus, we suggest that the LPV dosage should not be increased during pregnancy.

Adverse drug reactions associated with antiretroviral therapy during pregnancy

INTRODUCTION

Antiretroviral (ARV) drug use during pregnancy significantly reduces mother-to-child HIV transmission, delays disease progression in the women and reduces the risk of HIV transmission to HIV-serodiscordant partners. Pregnant women are susceptible to the same adverse reactions to ARVs as nonpregnant adults as well as to specific pregnancy-related reactions. In addition, we should consider adverse pregnancy outcomes and adverse reactions in children exposed to ARVs during intrauterine life. However, studies designed to assess the safety of ARV in pregnant women are rare, usually with few participants and short follow-up periods.

AREAS COVERED

In this review, we discuss studies reporting adverse reactions to ARV drugs, including maternal toxicity, adverse pregnancy outcomes and the consequences of exposure to ARV in infants. We included results of observational studies, both prospective and retrospective, as well as randomized clinical trials, systematic reviews and meta-analyses.

EXPERT OPINION

The benefits of ARV use during pregnancy outweigh the risks of adverse reactions identified to date. More studies are needed to assess the adverse effects in the medium- and long term in children exposed to ARVs during pregnancy, as well as pregnant women using lifelong antiretroviral therapy and more recently available drugs.

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?

Nutritional status and metabolic disorders in HIV-exposed uninfected prepubertal children

OBJECTIVE

The objective of the study was to assess the nutritional status and metabolic alterations in HIV-exposed uninfected (HIVe) children compared with HIV-unexposed (HIVn) children.

METHODS

A cross-sectional study was carried out with 76 children distributed into two groups: HIVe (n = 31) and HIVn (n = 45). Biochemical data (hematologic test, lipid profile, insulin resistance, hepatic profile, and C-reactive protein) were evaluated. Anthropometric parameters and body composition analyses were performed.

RESULTS

The groups were similar regarding body mass index-for-age z-scores (P = 0.297) and height-for-age z-scores (P = 0.666). HIVe had a higher dyslipidemia prevalence (38.7% versus 11.1%; P = 0.010), altered total cholesterol (TC) values (19.4% versus 2.2%; P = 0.016) higher LDL-C mean levels (97.8 mg/dl versus 86 mg/dl; P = 0.028), borderline low-density lipoprotein cholesterol (LDL-C) (40% versus 14%; P = 0.011) and TC (41.9% versus 20%; P = 0.038) compared with HIVn.

CONCLUSION

Despite the similar nutritional status between groups, our data clearly demonstrated a higher prevalence of dyslipidemia, altered TC, higher LDL-C levels and also LDL-C and TC borderline values in HIVe children.

Safety of protease inhibitors in HIV-infected pregnant women

The dire conditions of the human immunodeficiency virus/acquired immune deficiency syndrome epidemic and the immense benefits of antiretroviral prophylaxis in prevention of mother-to-child transmission far outweigh the potential for adverse effects and undeniably justify the rapid and widespread use of this therapy, despite incomplete safety data. Highly active antiretroviral therapy has now become standard care, and more than half the validated regimens include protease inhibitors. This paper reviews current knowledge of the safety of these drugs during pregnancy, in terms of maternal and fetal outcomes. Transfer of protease inhibitors across the placenta is known to be minimal, and current data about birth defects and fetal malignancies are reassuring. Maternal liver function and glucose metabolism should be monitored in women treated with protease inhibitor-based regimens, but concerns about the development of maternal resistance, should treatment be discontinued, have been shown to be groundless. Neonates should be screened for hematologic abnormalities, although these are rarely severe or permanent and are not usually related to the protease inhibitor component of the antiretroviral combination. Current findings concerning pre-eclampsia and growth restriction are discordant, and further research is needed to address the question of placental vascular complications. The increased risk of preterm birth attributed to protease inhibitors should be interpreted with caution considering the discrepant results and the multitude of confounding factors often overlooked. Although data are thus far reassuring, further research is needed to shed light on unresolved controversies about the safety of protease inhibitors during pregnancy.

Genotoxicity profile of azidothymidine in vitro

Azidothymidine (Zidovudine, AZT) is part of the standard care of treatment for acquired immunodeficiency syndrome since many years. A great number of studies on the genotoxic potential of AZT have been published, but no comprehensive hypothesis yet explains all observations. We investigated a multitude of genotoxic endpoints, both in vitro and in vivo, with the goal to complete the picture. The mutagenic potential of AZT in bacteria was found to be restricted to strains with an "ochre" target sequence and could be abrogated both by thymidine supplementation and rat liver S9 mix. Single-strand breaks in mammalian cells were detected in the comet assay after short-term treatment (3h) with AZT, which did not induce micronuclei. The latter were mainly seen after prolonged exposure (24 and 48h) and are probably not directly related to AZT incorporation into DNA. Our data demonstrate that short-term exposure to low AZT concentrations does not induce biologically relevant micronucleation. Only treatment with high concentrations of AZT for prolonged time periods manifests in substantial micronucleus induction. Furthermore, we found that high concentrations of thymidine have no effect in the comet assay but increase micronucleus frequency in a manner very similar to AZT. These results lead us to the following hypothesis: AZT is triphosphorylated and then incorporated into DNA strands, leading to mutations and cytotoxicity. Cellular attempts to repair these DNA lesions as well as stalled replication forks due to chain termination are detectable with the comet assay. Increased micronucleus frequency is likely related to nucleotide pool imbalance.

Leukocyte telomere length in HIV-infected pregnant women treated with antiretroviral drugs during pregnancy and their uninfected infants

OBJECTIVES

HIV disease can lead to accelerated telomere attrition, although certain drugs used as part of antiretroviral therapy (ART) can inhibit telomerase reverse transcriptase activity. This could in turn lead to shorter telomeres. We hypothesized that HIV and ART exposure would be associated with shorter leukocyte telomere length (TL) in exposed mother/infant pairs compared with controls.

METHODS

In these retrospective and prospective observational cohort studies, TL was evaluated in peripheral blood leukocytes obtained from HIV-infected pregnant women treated with ART and their uninfected infants, and compared with HIV untreated (retrospective cohort) or HIV mothers and their infants (prospective cohort).

RESULTS

In HIV-infected ART-exposed mothers, leukocyte TL was not significantly shorter than that in HIV untreated mothers or HIV controls, nor was their infants' TL significantly different. Cord blood of ART-exposed infants exhibited TL shorter than that from infants born to HIV-negative mothers. Placenta also showed evidence of shorter TL after adjustment for relevant covariates. Factors associated with shorter maternal and infant TL included smoking and the use of drugs of addiction in pregnancy.

CONCLUSIONS

These results suggest that maternal HIV infection or exposure to ART has minimal effect on infant leukocyte TL, a reassuring finding. In contrast, tissues that express higher telomerase activity such as umbilical cord blood and placenta appear comparatively more affected by ART. Smoking and the use of drugs of addiction have a negative impact on maternal and infant leukocyte TL, possibly through oxidative telomere damage.

Transplacental genotoxicity evaluation of cypermethrin using alkaline comet assay

Transplacental genotoxic effect of cypermethrin technical was investigated. Three doses (25, 50 and 75 mg/kg body weight) were administered to groups of pregnant Wistar rats during 6-15 days of gestation. Animals were killed on gestation day 20. Fetal blood and liver samples were evaluated for DNA damage using alkaline comet assay. A marginal increase in the mean percentage of DNA damage was recorded in both blood and liver samples of fetuses from cypermethrin-treated dams, but the values were not statistically significant. No skeletal or visceral fetal abnormalities were recorded in treated groups. Nevertheless, the results lead to an understanding that transplacental exposure to cypermethrin can induce low levels of DNA damage in fetuses. This observation could be an explanation for the teratogenic effect exhibited by this chemical in many other studies. The results indicate that cypermethrin may be transplacentally genotoxic. The authors propose more detailed investigations for validating the current findings.

Impact of EMS outreach: successful developments in Latin America

This collection of articles was inspired by the long-standing relationship between the Environmental Mutagen Society and Latin American scientists, and by the program for the 39th Environmental Mutagen Society meeting in Puerto Rico in 2008, which included a symposium featuring "South of the border" scientists. This collection, compiled by Graciela Spivak and Ofelia Olivero, both originally from Argentina, highlights scientists who work in or were trained in Latin American countries and in Puerto Rico in a variety of scientific specialties related to DNA repair and cancer susceptibility, genomic organization and stability, genetic diversity, and environmental contaminants.

Long-term exposure to AZT, but not d4T, increases endothelial cell oxidative stress and mitochondrial dysfunction

Nucleoside reverse transcriptase inhibitors (NRTIs), such as zidovudine (AZT) and stavudine (d4T), cause toxicities to numerous tissues, including the liver and vasculature. While much is known about hepatic NRTI toxicity, the mechanism of toxicity in endothelial cells is incompletely understood. Human aortic endothelial and HepG2 liver cells were exposed to 1 muM AZT or d4T for up to 5 weeks. Markers of oxidative stress, mitochondrial function, NRTI phosphorylation, mitochondrial DNA (mtDNA) levels, and cytotoxicity were monitored over time. In endothelial cells, AZT significantly oxidized glutathione redox potential, increased total cellular and mitochondrial-specific superoxide, decreased mitochondrial membrane potential, increased lactate release, and caused cell death from weeks 3 through 5. Toxicity occurred in the absence of di- and tri-phosphorylated AZT and mtDNA depletion. These data show that oxidative stress and mitochondrial dysfunction in endothelial cells occur with a physiologically relevant concentration of AZT, and require long-term exposure to develop. In contrast, d4T did not induce endothelial oxidative stress, mitochondrial dysfunction, or cytotoxicity despite the presence of d4T-triphosphate. Both drugs depleted mtDNA in HepG2 cells without causing cell death. Endothelial cells are more susceptible to AZT-induced toxicity than HepG2 cells, and AZT caused greater endothelial dysfunction than d4T because of its pro-oxidative effects.