Micronuclei induced by reverse transcriptase inhibitors in mononucleated and binucleated cells as assessed by the cytokinesis-block micronucleus assay

HIV infection and frequency of micronucleus in human peripheral blood cells

Purpose

People living with HIV have higher rates of malignancies than the general population in the era of active antiretroviral therapy (ART). Genotoxic effects of HIV infection and/or ART that can induce neoplastic development are not yet well known. A prospective cohort study to investigate DNA damage measured through the micronuclei (MN) frequency in HIV-patients has been performed.

Methods

Peripheral blood mononuclear cells (PBMC) were isolated from 52 HIV-patients treated with ART and 55 healthy controls.

Results

By the comparison of MN frequency, a significant difference between HIV-patients (15.5 ± 9.8) and controls (6.0 ± 3.6) (p < 0.001) has been revealed. In univariate linear regression analysis, HCV infection (r = 0.31; p < 0.001), HIV-RNA (r = 0.29; p < 0.03) and duration of infection (r = – 0.16; p < 0.25) were associated with MN frequency; while only viral load (VL) significantly correlates (r = 0.29; p < 0.05) in a multiple regression model.

Conclusions

The association of VL with MN frequency supports a genotoxic effect of HIV infection.

Quantification of micronuclei in exfoliated cells of human immunodeficiency virus/AIDS-infected female patients

Background

Micronucleus (MN) is a biomarker for cytotoxicity, which is formed during cell division. Increased MN scoring has been successfully used to recognize population groups at risk for cancers of oral cavity, cervix, urinary bladder and esophagus. Incorporating MN score along with cytological smear testing gives a better and cost-effective screening for high-risk patients.

Objective

This study evaluated the effectiveness of using MN score assessed from Papanicolaou (PAP) smears, as a biomarker for chromosomal damage in human immunodeficiency virus (HIV) patients.

Materials and Methods

Oral smears of 25 female HIV/AIDS patients, without habits such as chewing or smoking tobacco, and taking antiretroviral therapy (ART) at ART center, were recruited for the study. After careful oral examination and oral rinsing with normal saline, smears were prepared on slides by scraping the buccal mucosa with a wooden spatula. All the slides were fixed in 95% ethyl alcohol and stained with PAP stain, and 1000 cells were counted per patient. Based on Tolbert et al.'s criteria, MNs were identified, and quantitative scoring of MN was done on the basis of morphological assay.

Results

Mean ± standard deviation values of frequency of MNs in HIV-infected females were 73.40 ± 19.70 and in normal females were 38.08 ± 8.56.

Conclusion

MN scoring on the epithelial cells of buccal mucosa can be used as a biomarker in screening procedures for HIV patients.

Assessment of complex genomic alterations induced by AZT, 3TC, and the combination AZT +3TC

Highly active antiretroviral therapy (HAART) regimens are based on the use of nucleoside reverse transcriptase inhibitors (NRTIs), which are the main drugs used by patients infected with the human immunodeficiency virus (HIV). The use of NRTIs combinations has afforded clear clinical benefits to patients undergoing HAART. However, the combination of two NRTIs may increase the risk of genomic instability in comparison with the drugs administered individually. We analyzed the ability of zidovudine (AZT) and lamivudine (3TC), and the combination AZT +3TC to induce complex genomic alterations using the cytokinesis-block micronucleus (CBMN) assay in Chinese hamster ovary (CHO)-K1 cells. The 24-h cell treatment with individual NRTIs showed that AZT increased micronucleus frequencies and nucleoplasmic bridges (NPBs). No significant differences were observed for any parameters investigated after exposure of CHO-K1 cells to 3TC. The combination AZT +3TC significantly increased micronucleus frequencies. Analysis of interaction between these drugs suggested that antagonism occurs in all AZT +3TC concentrations. These results highlight the importance to investigate the genotoxic profile of NRTIs to develop safer intervention strategies in antiretroviral treatment protocols.

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.