Biomarkers and histopathologic changes in rats with monocrotaline-induced pulmonary hypertension following administration of antiretroviral medications.

Abstract

Pulmonary hypertension (PH) is a progressive life-threatening vasculopathy characterized by dysregulated pulmonary vascular remodelling that results in an increased pulmonary vascular resistance, right ventricular hypertrophy, right heart failure and untimely death. Human Immunodeficiency Virus (HIV) is a recognized cause of PH with a relatively stable prevalence of HIV associated PH of 0.5% in most developed countries. One of the animal models of PH is comprises a once off monocrotaline (MCT) in rats, which leads to PH that mimics typical PH presentation observed in humans. Early administration of antiretroviral medication has been shown to prevent the development of PH in human subjects, however, in advanced cases no significant improvement was reported. The impact of antiretroviral medications is controversial; however, nucleoside reverse transcriptase inhibitors (NRTI) and protease inhibitors (PI) have been shown to improve outcome in PH animal models. A potential connection between combination antiretroviral and PH in human subjects has been established which was contrary the protective effects of solely administer NRTI. The study was conducted to test the hypothesis that antiretroviral medications could ameliorate MCT induced PH in rat models and identify potential biomarker for PH. An approval was given by the Animal Research Ethics Committee of the institution (AREC/066/018M) of University of KwaZulu-Natal, Durban, South Africa, to conduct the study. Forty adult male Sprague-Dawley rats (body weight: 200-250 g) were randomly divided into five groups (n=8 per group). The treatment groups received a single intraperitoneal injection of MCT (60 mg kg-1) while the control group received an equivalent volume of intraperitoneal saline injection. Zidovudine (100 mg kg-1), ritonavir (30 mg kg-1), or combination of both drugs (zidovudine 100 mg kg-1 and ritonavir 30 mg kg-1) were administrated daily for the study period of 28 days to the rats in three of the four groups with MCT for 28 days respectively. On the twenty-eighth day of the study, rats were sacrificed, and the harvested lungs and hearts organ were analyzed. Gene expression was conducted using RT-PCR for the antioxidant’s enzymes, ASK-1 and a laboratory assay for lipid peroxidation was performed. A significantly higher mRNA gene expression of catalase, superoxide dismutase, and glutathione peroxidase in the heart tissue of the antiretroviral treated rats was observed and compared to the untreated groups. There was an increase in malondialdehyde (MDA) in the heart tissues of untreated rats (37.01±1.16 nmol/g, p<0.0001) compared to the control group (3.46±0.97 nmol/g) with an associated reduction in MDA by the antiretrovirals. Furthermore, an increase in the total antioxidant capacity (TAC) in AZT (0.85±0.02 nmol/g, p<0.0001), RTV (0.63±0.03 nmol/g, p<0.0001) and combination of AZT/RTV (0.77±0.06 nmol/g, p<0.0001) compared to untreated (0.28±0.025) rats. Furthermore, lower relative mRNA gene expression of ASK-1 was observed in the heart of the treated rats with zidovudine (2.67 ± 0.09, p < 0.0001), ritonavir (2.57 ±0.11, p < 0.0001) and a combination of both (2.75 ± 0.06, p < 0.0001) when compared to rats in the untreated group. An overexpressed mRNA gene of ASK-1 in the untreated rats (12.0 ± 0.90, p < 0.0001) when compared to the control. This study shows evidence that zidovudine and ritonavir ameliorate MCT-induced PH in rats by suppressing oxidative stress. Also, ASK-1 is a potential biomarker for anti-apoptotic characteristics of PH. Our findings indicate the antioxidative role of antiretroviral medications in PH and the role of biomarkers in PH.