Mitochondrial pathway of apoptosis and necrosis contribute to tenofovir disoproxil fumarate-induced renal damage in rats

Moringa oleifera Lam Leaf Extract Stimulates NRF2 and Attenuates ARV-Induced Toxicity in Human Liver Cells (HepG2)

The World Health Organization (WHO) reported that there are 37 million individuals living with the human immunodeficiency virus (HIV) worldwide, with the majority in South Africa. This chronic disease is managed by the effective use of antiretroviral (ARV) drugs. However, with prolonged use, ARV drug-induced toxicity remains a clinically complex problem. This study investigated the toxicity of ARV drugs on mitochondria and the NRF2 antioxidant pathway and its possible amelioration using Moringa oleifera Lam (MO) leaf extracts. This medicinal plant has a range of functional bioactive compounds. Liver (HepG2) cells were treated with individual ARV drugs: Tenofovir disoproxil fumarate (TDF), Emtricitabine (FTC), and Lamivudine (3TC) for 96 h, followed by MO leaf extracts for 24 h. Intracellular ROS, cytotoxicity, lipid peroxidation, total and reduced glutathione (GSH), ATP, and mitochondrial polarisation were determined. Finally, protein (pNRF2, NRF2, SOD2, CAT, and Sirt3) and mRNA (NRF2, CAT, NQO1 SOD2, Sirt3, and PGC1α) expression were measured using Western blot and qPCR, respectively. TDF, FTC, and 3TC significantly increased intracellular ROS and extracellular levels of both MDA and LDH. ARVs also reduced the GSH and ATP levels and altered the mitochondrial polarization. Further, ARVs reduced the expression of NRF2 SOD2, Sirt3, CAT, NQO1, UCP2 and PGC1α mRNA and consequently pNRF2, NRF2, SOD2, Sirt3 and CAT protein. In contrast, there was a significant reduction in the extracellular MDA and LDH levels post-MO treatment. MO significantly reduced intracellular ROS while significantly increasing GSH, ATP, and mitochondrial membrane polarization. The addition of MO to ARV-treated cells significantly upregulated the expression of NRF2, SOD2, Sirt3, CAT, UCP2, PGC1α, and NQO1 mRNA and pNRF2, NRF2, SOD2, Sirt3 proteins. Thus, MO ameliorates ARV-induced hepatotoxicity by scavenging oxidants by inducing the NRF2 antioxidant pathway. MO shows great therapeutic potential and may be considered a potential supplement to ameliorate ARV drug toxicity.

Tenofovir-induced osteopenia and hyperparathyroidism: A case report and literature review

Tenofovir disoproxil fumarate is the first-line antiviral therapy for chronic viral hepatitis B, but long-term use is associated with renal failure and hypophosphatemic osteomalacia. Tenofovir disoproxil fumarate-induced osteoporosis and secondary hyperparathyroidism are less commonly reported. Herein, we describe the case of a patient with bone and multijoint pain who was initially misdiagnosed as having normocalcemic primary hyperparathyroidism associated with prolonged exposure to tenofovir disoproxil fumarate. The patient's 24-h urinary calcium and phosphorus excretion levels and serum calcium levels were at the lower end of the normal range. After reviewing these findings, the diagnosis was amended to osteoporosis and secondary hyperparathyroidism caused by tenofovir disoproxil fumarate. In this report, we describe the differences in clinical and laboratory manifestations of hyperparathyroidism induced by tenofovir disoproxil fumarate and normocalcemic primary hyperparathyroidism. We also discuss relevant pathophysiological mechanisms and propose a feasible treatment strategy.

Mitochondria and ageing with HIV

PURPOSE OF REVIEW

Some older people living with HIV (PLWH) exhibit features of unsuccessful ageing, such as frailty. Mitochondrial dysfunction is one of the best characterized ageing mechanisms. There has been recent interest in whether some people ageing with HIV may have an excess of mitochondrial dysfunction. This review aims to address this question through: analogy with ageing and chronic disease; discussion of the key unknowns; suggested ways that measures of mitochondrial dysfunction might be incorporated into HIV research studies.

RECENT FINDINGS

Recent data suggest that mitochondrial dysfunction in PLWH may not be wholly a legacy effect of historical nucleoside analog reverse transcriptase inhibitor exposures. Research in the non-HIV setting has altered our understanding of the important mediators of mitochondrial dysfunction in ageing.

SUMMARY

Mitochondrial dysfunction is a very plausible driver of adverse ageing phenotypes in some older PLWH. As such it may be a target for therapeutic interventions. Currently, however, there remain considerable uncertainties around the extent of this phenomenon, and its relative importance. Current studies are likely to clarify these questions over the next few years.

Diverse Roles of Mitochondria in Renal Injury from Environmental Toxicants and Therapeutic Drugs

Mitochondria are well-known to function as the primary sites of ATP synthesis in most mammalian cells, including the renal proximal tubule. Other functions have also been associated with different mitochondrial activities, including the regulation of redox status and the initiation of mitophagy and apoptosis. Mechanisms for the membrane transport of glutathione (GSH) and various GSH-derived metabolites across the mitochondrial inner membrane of renal proximal tubular cells are critical determinants of these functions and may serve as pharmacological targets for potential therapeutic approaches. Specific interactions of reactive intermediates, derived from drug metabolism, with molecular components in mitochondria have been identified as early steps in diverse forms of chemically-induced nephrotoxicity. Applying this key observation, we developed a novel hypothesis regarding the identification of early, sensitive, and specific biomarkers of exposure to nephrotoxicants. The underlying concept is that upon exposure to a diverse array of environmental contaminants, as well as therapeutic drugs whose efficacy is limited by nephrotoxicity, renal mitochondria will release both high- and low-molecular-weight components into the urine or the extracellular medium in an in vitro model. The detection of these components may then serve as indicators of exposure before irreversible renal injury has occurred.

TUNEL Assay: A Powerful Tool for Kidney Injury Evaluation

Terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assay is a long-established assay used to detect cell death-associated DNA fragmentation (3'-OH DNA termini) by endonucleases. Because these enzymes are particularly active in the kidney, TUNEL is widely used to identify and quantify DNA fragmentation and cell death in cultured kidney cells and animal and human kidneys resulting from toxic or hypoxic injury. The early characterization of TUNEL as an apoptotic assay has led to numerous misinterpretations of the mechanisms of kidney cell injury. Nevertheless, TUNEL is becoming increasingly popular for kidney injury assessment because it can be used universally in cultured and tissue cells and for all mechanisms of cell death. Furthermore, it is sensitive, accurate, quantitative, easily linked to particular cells or tissue compartments, and can be combined with immunohistochemistry to allow reliable identification of cell types or likely mechanisms of cell death. Traditionally, TUNEL analysis has been limited to the presence or absence of a TUNEL signal. However, additional information on the mechanism of cell death can be obtained from the analysis of TUNEL patterns.

Melatonin protects against tenofovir-induced nephrotoxicity in rats by targeting multiple cellular pathways

Nephrotoxicity is a dose-limiting side effect of long-term use of tenofovir, a reverse transcriptase inhibitor that is used for the treatment of HIV infection and chronic hepatitis B infection. Identifying an agent that prevents tenofovir disoproxil fumarate (TDF)-induced renal injury can lead to its better tolerance, and a more effective treatment can be achieved. The present study is aimed at investigating whether melatonin, a potent antioxidant and anti-inflammatory agent, protects against TDF nephrotoxicity in rats and to determine its cellular targets. Rats were divided into groups and treated as follows. Group I (control): Rats in this group (n = 6) received sterile water only by gavage for 35 days. Group II: Rats (n = 6) in this group received 600 mg/kg body weight TDF in sterile water by gavage for 35 days. Group III: Rats (n = 6) in this group received once daily 20 mg/kg bodyweight melatonin i.p. 2 h before the administration of 600 mg/kg body weight TDF in sterile water by gavage for 35 days. Group IV: Rats were pretreated daily with 20 mg/kg body weight melatonin i.p. 2 h before the administration of sterile water by gavage. All the rats were sacrificed on the 36th day, after overnight fast. Melatonin pretreatment protected the rats against TDF nephrotoxicity both histologically and biochemically. Biochemically, melatonin pretreatment attenuated TDF-induced, oxidative stress, nitrosative stress, mitochondrial pathway of apoptosis, PARP overactivation and preserved proximal tubular function (p < 0.01). This suggests that melatonin may be useful in ameliorating TDF nephrotoxicity.