Effect of antiretroviral drugs on the DNA damage in mice

Oral Administration of Efavirenz Dysregulates the Tph2 Gene in Brain Serotonergic Areas and Alters Weight and Mood in Mice

Most HIV-antiretroviral drugs have adverse effects. Efavirenz (EFV) is an example of a drug with neuropsychiatric effects, such as anxiety, depression, and suicidal thoughts, in people living with HIV (PLWH). The mechanisms by which EFV causes neuropsychiatric alterations in PLWH are complex, multifactorial, and not fully understood, although several studies in animals have reported changes in brain energy metabolism, alterations in monoamine turnover, GABA, and glutamate levels, and changes in 5-HT receptors. In this report, we studied the effects of EFV on the serotonergic system in healthy mice, specifically, whether EFV results in alterations in the levels of the tryptophan hydroxylase 2 (Tph2) gene in the brain. EFV (10 mg/kg) and distilled water (1.5 µL/kg) (control group) were orally administered to the mice for 36 days. At the end of the treatment, Tph2 expression levels in mouse brains were measured, and mood was evaluated by three trials: the forced swim test, elevated plus maze, and open field test. Our results revealed dysregulation of Tph2 expression in the brainstem, amygdala, and hypothalamus in the EFV group, and 5-HT levels increased in the amygdala in the EFV group. In the behavioral tests, mice given EFV exhibited a passive avoidance response in the forced swim test and anxiety-like behavior in the elevated plus maze, and they lost weight. Herein, for the first time, we showed that EFV triggered dysregulation of the Tph2 gene in the three serotonergic areas studied; and 5-HT levels increased in the amygdala using the ELISA method. However, further studies will be necessary to clarify the increase of 5-HT in the amygdala as well as understand the paradoxical decrease in body weight with the simultaneous increase in food consumption. It will also be necessary to measure 5-HT by other techniques different from ELISA, such as HPLC.

Effects of combination antiretroviral drugs (cART) on hippocampal neuroplasticity in female mice

The incidence of HIV-associated neurocognitive disorder (HAND) continues despite the introduction of combination antiretroviral drugs (cART). Several studies have reported the neurotoxicity of individual antiretroviral drugs (monotherapy), while the common approach for HIV treatment is through cART. Hence, the current study investigated the effects of long-term exposure to cART on cognitive function, oxidative damage, autophagy, and neuroplasticity in the hippocampus of mice. Female Balb/c mice received a once-a-day oral dose of cART composed of emtricitabine + tenofovir disoproxil fumarate or vehicle for 8 weeks. On week 7 of drug administration, all mice were assessed for spatial learning in the Morris water maze (MWM), and then on week 8, mice were sacrificed, and hippocampal tissue dissected from the brain. For biochemical analyses, we measured the concentration of 4-hydroxynonenal, and the expression of autophagic marker LC3B, synaptophysin, and brain-derived neurotrophic factor (BDNF) in the hippocampus. Our results showed that cART exposure increased escape latency in the MWM test. The cART-treated mice also showed increased 4-hydroxynonenal concentration and expression of LC3B. Furthermore, cART treatment decreased the expression of synaptophysin and BDNF. These findings further support the evidence that cART may be neurotoxic and therefore may play a role in the neuropathogenesis of HAND.

Anti-HIV drugs promote β-amyloid deposition and impair learning and memory in BALB/c mice

OBJECTIVES

Growing evidence suggested that antiretroviral (ARV) drugs may promote amyloid beta (Aβ) accumulation in HIV-1-infected brain and the persistence of HIV-associated neurocognitive disorders (HANDs). It has also been shown that lipid peroxidation upregulates β-site amyloid precursor protein (APP) cleaving enzyme 1 (BACE1) expression and subsequently promotes Aβ peptide production. In the present study, we examined whether chronic exposure to the anti-HIV drugs tenofovir disoproxil fumarate (TDF) and nevirapine induces lipid peroxidation thereby promoting BACE1 and Aβ generation and consequently impair cognitive function in mice.

METHODS

TDF or nevirapine was orally administered to female BALB/c mice once a day for 8 weeks. On the 7th week of treatment, spatial learning and memory were assessed using the Morris water maze test. The levels of lipid peroxidation, BACE1, amyloid β 1-42 (Aβ1-42) and Aβ deposits were measured in the hippocampal tissue upon completion of treatment.

RESULTS

Chronic administration of nevirapine induced spatial learning and memory impairment in the Morris water maze test, whereas TDF did not have an effect. TDF and nevirapine administration increased hippocampal lipid peroxidation and Aβ1-42 concentration. Nevirapine further upregulated BACE1 expression and Aβ deposits.

CONCLUSION

Our results suggest that chronic exposure to TDF and nevirapine contributes to hippocampal lipid peroxidation and Aβ accumulation, respectively, as well as spatial learning and memory deficits in mice even in the absence of HIV infection. These findings further support a possible link between ARV drug toxicity, Aβ accumulation and the persistence of HANDs.

Antiretroviral Therapy Initiation Alters the Redox System of Asymptomatic HIV-Infected Individuals: A Longitudinal Study

Background. The combination antiretroviral therapy (cART) increases the oxidative stress in HIV-infected people, which in turn favors the onset and aggravation of non-AIDS comorbidities, a common situation affecting these individuals. We aimed to evaluate the influence of cART initiation on oxidative stress parameters. This is a longitudinal study including 30 asymptomatic patients divided according to their CD4+ T cell count (G1: <500 cell/mL; G2: >500 cell/mL) before (M0) and after (M1) cART initiation. We analyzed total antioxidant capacity (TAC), fat-soluble vitamins, malondialdehyde, 8-isoprostane, and DNA damage. Results. Results showed a decrease in TAC, retinol, α-tocopherol, and some carotenoids, in addition to a significant increase in DNA damage at M1. These changes were more evident in G2 subjects. Moreover, there was a significant 8-isoprostane increase at M1 in individuals belonging to G1. Conclusion. The results indicate that cART interfered in the redox system, mainly by reducing the antioxidant defenses. In addition, patients who had CD4+ T counts higher than 500 cells/mm³ showed more susceptibility to genotoxicity, while patients with less CD4+ T counts displayed more damage triggered by lipoperoxidation. Considering the early beginning of cART, its chronic use, and its capacity to alter the redox status, further long-term studies on larger cohorts are needed to define the best time to initiate therapy and to investigate new strategies to delay the development of non-AIDS diseases.

Genotoxic and Cytotoxic Effects of Antiretroviral Combinations in Mice Bone Marrow

Commonly used guidelines for the management of human immunodeficiency virus (HIV) infection (highly active antiretroviral therapy, HAART) include drug combinations such as tenofovir disoproxil fumarate (TDF) + lamivudine (3TC) and combivir [zidovudine (AZT) + 3TC] + efavirenz (EFV). These combinations may enhance the genotoxic effects induced by such drugs individually, since the therapy requires lifelong adherence and the drugs have unknown effects during treatment. Thus, the evaluation of the benefits and risks of HAART is of great importance. In order to assess the cytotoxic and genotoxic potential of three concentrations of each of the antiretroviral combinations TDF + 3TC (800 + 400, 1600 + 800, and 3200 + 1600 mg/kg body weight, BW) and combivir + EFV (200 + 100 + 400, 400 + 200 + 800, and 800 + 400 + 1600 mg/kg BW) after two exposure periods (24 h and 48 h), in the present study the in vivo comet assay (single-cell gel electrophoresis) and the mouse bone marrow micronucleus test were used. Neither TDF + 3TC nor combivir + EFV induced DNA damage at any concentrations tested after 24 h or 48 h using the comet assay. After 24 h, both combinations increased the micronucleus frequency at all concentrations tested. After 48 h, combivir + EFV increased the micronucleated polychromatic erythrocyte (MNPCE) frequency at the two highest concentrations tested. Polychromatic erythrocytes (PCE)/normochromatic erythrocytes (NCE) ratio was high for both combinations, suggesting that they can be mitogenic. Since genotoxicity may be related to carcinogenesis, it is necessary to conduct further studies to verify the long-term mutagenic effects of these drugs.

Efavirenz biotransformation as an up-stream event of mood changes in HIV-infected patients

Efavirenz is a drug of choice for adults and children infected with the human immunodeficiency virus. Notably, up to 35% of patients on efavirenz suffer from mood changes. This work aimed to investigate efavirenz biotransformation into 8-hydroxy-efavirenz as an up-stream event of mood changes and to evaluate the suitability of 8-hydroxy-efavirenz biomonitoring for the minimization of these manifestations. A case-control study with two age-matched groups of HIV-infected male patients was performed in a group without adverse central nervous system complaints (28 patients) and a group presenting mood changes (14 patients). The plasma concentration of non-conjugated 8-hydroxy-efavirenz was higher in patients with mood changes (p=0.020). An association between efavirenz and 8-hydroxy-efavirenz-glucuronide was found (Spearman r=0.414, p<0.010), only within therapeutic efavirenz concentrations. This correlation was not observed in patients with toxic (>4mg/L) plasma concentrations of the parent drug. We conclude that metabolism to 8-hydroxy-efavirenz is associated with efavirenz-related mood changes, which suggests that the concentration of this metabolite is a suitable parameter for therapeutic drug monitoring aimed at controlling these manifestations. Moreover, our data suggest that 8-hydroxy-efavirenz is able to cross the blood-brain barrier and that the peripheral detoxification of 8-hydroxy-efavirenz by glucuronidation may be inhibited by toxic efavirenz concentrations.

Nevirapine induces apoptosis in liver (HepG2) cells

OBJECTIVE

To generate insights into the mechanism of NVP induced hepatotoxicity.

METHODS

Liver (HepG2) cells were cultured with various concentrations of NVP. This cell line was chosen because it has low expression of cytochrome P450, allowing evaluation of the effects of NVP rather than specific metabolites. Cytotoxicity was determined using a proliferation assay and cell numbers were monitored using trypan blue exclusion assay for long term culture experiments and apoptosis induction was determined by morphological and biochemical investigation.

RESULTS

HepG2 cells treated with the highest concentration of NVP tested (819 μM) initially showed a rounded morphology and all cells had died by week three of exposure. Nuclear condensation and fragmentation, increased Annexin V/propidium iodide staining and caspase 9 activation all supported the induction of apoptosis in HepG2 cells in response to NVP treatment.

CONCLUSIONS

There is a clear induction of apoptosis in response to NVP which suggests that NVP has significant cytotoxicity, over and above any cytotoxicity of metabolites and may contribute directly to patient hepatotoxicity.