Depletion of the cellular antioxidant system contributes to tenofovir disoproxil fumarate - induced mitochondrial damage and increased oxido-nitrosative stress in the kidney

Mitotherapy inhibits against tenofovir induced nephrotoxicity on rat renal proximal tubular cells

Tenofovir, as nucleotide reverse transcriptase inhibitors (NRTIs), is used to prevent and cure HIV/AIDS. Ample evidence confirmed that the nephrotoxicity of tenofovir has been linked to mitochondrial dysfunction. It seems that transplantation with healthy mitochondria instead of damaged mitochondria may be a beneficial approach to therapy. Therefore, it decided to investigate the impact of mitotherapy on tenofovir against renal proximal tubular cells (RPTCs) toxicity by measurement of oxidative stress and cytotoxicity biomarkers and restoring of mitochondrial function on isolated mitochondria. EC50 of tenofovir was achieved at 40 μM following 2 h incubation in Earle's solution (pH = 7.4; 37 °C). Freshly isolated mitochondria (80 μg/ml) were added to damage RPTCs affected by tenofovir in treated groups. One Way ANOVA analysis showed that healthy mitochondrial transplantation decreased oxidative stress biomarkers following tenofovir toxicity in RPTCs. Our data revealed that mitotherapy makes cell survival possible in RPTCs affected by tenofovir. In addition, it supposed that a novel and ideal strategy for the treatment of chemicals-induced nephrotoxicity.

Molecular mechanisms of nano-sized polystyrene plastics induced cytotoxicity and immunotoxicity in Eisenia fetida

Nanoplastics (NPs) are currently everywhere and environmental pollution by NPs is a pressing global problem. Nevertheless, until now, few studies have concentrated on the mechanisms and pathways of cytotoxic effects and immune dysfunction of NPs on soil organisms employing a multidimensional strategy. Hence, earthworm immune cells and immunity protein lysozyme (LZM) were selected as specific receptors to uncover the underlying mechanisms of cytotoxicity, genotoxicity, and immunotoxicity resulting from exposure to polystyrene nanoplastics (PS-NPs), and the binding mechanisms of PS-NPs-LZM interaction. Results on cells indicated that when earthworm immune cells were exposed to high-dose PS-NPs, it caused a notable rise in the release of reactive oxygen species (ROS), resulting in oxidative stress. PS-NPs exposure significantly decreased the cell viability of earthworm immune cells, inducing cytotoxicity through ROS-mediated oxidative stress pathway, and oxidative injury effects, including reduced antioxidant defenses, lipid peroxidation, DNA damage, and protein oxidation. Moreover, PS-NPs stress inhibited the intracellular LZM activity in immune cells, resulting in impaired immune function and immunotoxicity by activating the oxidative stress pathway mediated by ROS. The results from molecular studies revealed that PS-NPs binding destroyed the LZM structure and conformation, including secondary structure changes, protein skeleton unfolding/loosening, fluorescence sensitization, microenvironment changes, and particle size changes. Molecular docking suggested that PS-NPs combined with active center of LZM easier and inhibited the protein function more, and formed a hydrophobic interaction with TRP 62, a crucial amino acid residue closely associated with the function and conformation of LZM. This is also responsible for LZM conformational changes and functional inhibition /inactivation. These results of this research offer a fresh outlook on evaluating the detriment of NPs to the immune function of soil organisms using cellular and molecular strategies.

Protective and Ameliorative Effects of Hydroethanolic Extract of Piper nigrum (L.) Stem against Antiretroviral Therapy-Induced Hepatotoxicity and Dyslipidemia in Wistar Rats

Antiretroviral therapy (ART) has revolutionized the lives of people living with HIV/AIDS by overall improving their quality of life and increasing life expectancy. However, ART-associated hepatotoxicity and metabolic disorders in HIV/AIDS patients are growing concerns to clinicians, especially due to the long-term use of the drugs. This study reported on the phytochemical and pharmacological profile of hydroethanolic extracts of Piper nigrum stem (PNS) and evaluated its protective effect against tenofovir/lamivudine/efavirenz (TLE)-induced hepatotoxicity and dyslipidemia in Wistar rats. Cytotoxic, antioxidant, and anti-inflammatory assays were performed on PNS. Thirty-six rats divided into 6 groups of 6 animals/group were administered: distilled water, 17 mg/kg TLE, 17 mg/kg TLE and 100 mg/kg silymarin, 17 mg/kg TLE, and Piper extract (200 mg/kg, 400 mg/kg, or 800 mg/kg) orally for 28 days. The body weight of animals was recorded every 7 days. On Day 29, the rats were sacrificed, and blood samples were collected for hematological and biochemical tests. Portions of the liver and kidneys were collected for histological evaluation, while liver homogenates were prepared from the rest to measure antioxidant enzymes. PNS possessed in vitro cytotoxic, antioxidant, and anti-inflammatory activities. A significant decrease (p < 0.05) in the body weight of rats treated with PNS was observed. A significant high platelet count (p < 0.05) was observed in the PNS800 mg/kg group. A considerable decrease in alkaline phosphatase and triglycerides was observed in the silymarin and PNS group compared to the TLE-only group. The findings also show a significant increase in catalase and glutathione in the TLE-only group compared to the normal group, while SOD decreased. Histological observations revealed normal hepatic and renal tissues in the silymarin, and PNS-treated groups compared to the normal control, while leucocyte infiltration was observed in the TLE-only group. These results suggest that PNS extract possessed antioxidant activity that alleviated TLE-induced toxicity. Further studies are necessary to understand the pharmacokinetic interactions between ART and PNS.

Effects of Tenofovir Disoproxil Fumarate on Bone Quality beyond Bone Density-A Scoping Review of the Literature

Tenofovir disoproxil fumarate (TDF) is a widely used pharmacological agent for the treatment of human immunodeficiency virus infection. While prolonged exposure to TDF has been associated with a decrease in bone mineral density (BMD) and increased fracture risk, limited discussion exists on its effects on various aspects of bone quality. This scoping review aims to provide a comprehensive overview of the impact of TDF on bone quality beyond BMD. A literature search was conducted using the PubMed and Scopus databases to identify studies investigating the effects of TDF on bone quality. Original research articles written in English, irrespective of study type or publication year, were included in the review. Seven articles met the inclusion criteria. Findings indicate that prolonged exposure to TDF adversely affects bone microarchitecture and strength, impeding fracture healing and skeletal microdamage repair. The observed effects suggest a complex interplay involving bone cell signalling, cytokines and bone remodelling processes as potential mechanisms underlying TDF's impact on bone quality. As a conclusion, TDF impairs bone remodelling and microarchitecture by influencing dynamic bone cell behaviour and signalling pathways. Future studies should delve deeper into understanding the intricate negative effects of TDF on bone and explore strategies for reversing these effects.

Altered methionine-sulfone levels are associated with impaired growth in HIV-exposed-uninfected children

OBJECTIVE

To determine immune-metabolic dysregulation in children born to women living with HIV.

METHODS

Longitudinal immune-metabolomic analyses of plasma of 32 pregnant women with HIV (WHIV) and 12 uninfected women and their children up to 1.5 years of age were performed.

RESULTS

Using liquid chromatography-mass spectrometry and a multiplex bead assay, 280 metabolites (57 amino acids, 116 positive lipids, 107 signalling lipids) and 24 immune mediators (e.g. cytokines) were quantified. combinational antiretroviral therapy (cART) exposure was categorized as cART initiation preconception (long), cART initiation postconception up to 4 weeks before birth (medium) and cART initiation within 3 weeks of birth (short). Plasma metabolite profiles differed between HIV-exposed-uninfected (HEU)-children with long cART exposure compared to HIV-unexposed-children (HUU). Specifically, higher levels of methionine-sulfone, which is associated with oxidative stress, were detected in HEU-children with long cART exposure compared to HUU-children. High infant methionine-sulfone levels were reflected by high prenatal plasma levels in the mother. Increased methionine-sulfone levels in the children were associated with decreased growth, including both weight and length.

CONCLUSION

These findings based on longitudinal data demonstrate that dysregulation of metabolite networks associated with oxidative stress in children born to WHIV is associated with restricted infant growth.

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.

Integration of High-Throughput Imaging and Multiparametric Metabolic Profiling Reveals a Mitochondrial Mechanism of Tenofovir Toxicity

Nephrotoxicity is a major cause of kidney disease and failure in drug development, but understanding of cellular mechanisms is limited, highlighting the need for better experimental models and methodological approaches. Most nephrotoxins damage the proximal tubule (PT), causing functional impairment of solute reabsorption and systemic metabolic complications. The antiviral drug tenofovir disoproxil fumarate (TDF) is an archetypal nephrotoxin, inducing mitochondrial abnormalities and urinary solute wasting, for reasons that were previously unclear. Here, we developed an automated, high-throughput imaging pipeline to screen the effects of TDF on solute transport and mitochondrial morphology in human-derived RPTEC/TERT1 cells, and leveraged this to generate realistic models of functional toxicity. By applying multiparametric metabolic profiling-including oxygen consumption measurements, metabolomics, and transcriptomics-we elucidated a highly robust molecular fingerprint of TDF exposure. Crucially, we identified that the active metabolite inhibits complex V (ATP synthase), and that TDF treatment causes rapid, dose-dependent loss of complex V activity and expression. Moreover, we found evidence of complex V suppression in kidney biopsies from humans with TDF toxicity. Thus, we demonstrate an effective and convenient experimental approach to screen for disease relevant functional defects in kidney cells in vitro, and reveal a new paradigm for understanding the pathogenesis of a substantial cause of nephrotoxicity.

Evaluation of tenofovir disoproxil fumarate loaded silver nanoparticle on testicular morphology in experimental type-2 diabetic rats

Reproductive derangement and metabolic disorders in human immunodeficiency virus (HIV) infected persons require a nanoparticle delivery system to convey antiretroviral drugs to the anatomical sanctuary such as testis. This study investigated the effects of tenofovir disoproxil fumarate (TDF) loaded silver nanoparticles (AgNPs) on the testicular oxidative stress, inflammatory cytokines and histology in male diabetic rats. Thirty-six Sprague-Dawley rats weighing 230 ± 20 g were randomly divided into diabetic and non-diabetic groups (n = 18). Diabetes was induced using the fructose-streptozotocin (Frt-STZ) rat model. Both groups were further divided into three (n = 6) and administered distilled water, TDF, or TDF-AgNP. Results obtained with the TDF-AgNP administration showed a significant increase (p < .05) in the reduced glutathione and catalase levels. Tumour necrosis factor-alpha and interleukin 6 were reduced in diabetic rats administered TDF-AgNP. More so, administration of TDF-AgNP to diabetic rats improved testicular histoarchitecture in diabetic rats. In addition, diabetic rats administered TDF-AgNP showed a significant reduction (p < .05) in blood glucose levels. TDF-AgNP to diabetic rats enhanced testicular antioxidant enzyme, reduced testicular inflammation, and alleviated structural derangements in the testis. Thus, the application of AgNP to deliver TDF may alleviate testicular toxicity and subsequently cater for neglected reproductive dysfunction during the management of HIV infection.

The Potential of Moringa oleifera to Ameliorate HAART-Induced Pathophysiological Complications

Highly active antiretroviral therapy (HAART) comprises a combination of two or three antiretroviral (ARV) drugs that are administered together in a single tablet. These drugs target different steps within the human immunodeficiency virus (HIV) life cycle, providing either a synergistic or additive antiviral effect; this enhances the efficiency in which viral replication is suppressed. HIV cannot be completely eliminated, making HAART a lifetime treatment. With long-term HAART usage, an increasing number of patients experience a broadening array of complications, and this significantly affects their quality of life, despite cautious use. The mechanism through which ARV drugs induce toxicity is associated with metabolic complications such as mitochondrial dysfunction, oxidative stress, and inflammation. To address this, it is necessary to improve ARV drug formulation without compromising its efficacy; alternatively, safe supplementary medicine may be a suitable solution. The medicinal plant Moringa oleifera (MO) is considered one of the most important sources of novel nutritionally and pharmacologically active compounds that have been shown to prevent and treat various diseases. MO leaves are rich in polyphenols, vitamins, minerals, and tannins; studies have confirmed the therapeutic properties of MO. MO leaves provide powerful antioxidants, scavenge free radicals, promote carbohydrate metabolism, and repair DNA. MO also induces anti-inflammatory, hepatoprotective, anti-proliferative, and anti-mutagenic effects. Therefore, MO can be a source of affordable and safe supplement therapy for HAART-induced toxicity. This review highlights the potential of MO leaves to protect against HAART-induced toxicity in HIV patients.

Changes in alanine aminotransferase levels after switching from tenofovir disoproxil fumarate (TDF) to tenofovir alafenamide (TAF) in HIV-positive people without viral hepatitis in the Swiss HIV Cohort Study

OBJECTIVES

We previously demonstrated an association between tenofovir disoproxil fumarate (TDF) and chronic liver enzyme elevation in the D:A:D study. The objective of the study was to assess changes in alanine aminotransferase (ALT) levels after switching from TDF to tenofovir alafenamide (TAF).

METHODS

We included Swiss HIV Cohort Study participants who switched from TDF to TAF with two or more ALT values in the 24 months before and two or more values in the 24 months after replacing TDF with TAF. Individuals with replicating viral hepatitis were excluded. Uni- and multivariable linear mixed models were used to explore changes in ALT values associated with switching from TDF to TAF, and to assess potential modifying effects.

RESULTS

A total of 1712 participants were included, contributing 6169 ALT values before and 5482 after switching. Median (interquartile range, IQR) age was 50 (42-57) years, and 75% were male. Median (IQR) ALT was 28 (22-38) U/L before and 24 (19-32) U/L after replacing TDF with TAF. ALT values decreased by 3.7 U/L (95% confidence interval: 3.2-4.2) after the switch. The median drop was larger in patients with chronic ALT elevation (defined as two or more elevated values for ≥ 6 months) compared with patients with normal ALT values (17.8 vs. 3.3 U/L, P < 0.001). We did not identify any major effect modifications of the ALT change with any of the potential variables studied.

CONCLUSIONS

Replacing TDF with TAF in HIV-monoinfected people led to a significant decrease in ALT values. Findings were not significantly affected by known risk factors for hepatotoxicity.

Analysis of long-term safety and efficacy of nucleos(t)ide analogue therapy for chronic hepatitis B throughout pregnancy

BACKGROUND

Limited data exist regarding the efficacy and long-term safety of nucleos(t)ide analogue therapy throughout pregnancy for women with chronic hepatitis B and their children.

METHODS

This retrospective cohort study included 165 women in total: 91 women received telbivudine (LDT) and 74 women received tenofovir (TDF) throughout pregnancy. The virological response and safety in women were recorded, and the physical development and bone mineral density in children were evaluated up to 5 years of age.

RESULTS

The rate of virological breakthrough in women was 4.24% overall (7.70% in LDT group and 0% in TDF group; P < 0.05). No cases of renal injury or other obstetric adverse events occurred in either group of women. Among the children, only one child had a significantly low Z score for weight for age (<-2), and no children had a significantly low Z score for height for age or bone mineral density. No significant difference was found between the children in the two groups.

CONCLUSIONS

Nucleos(t)ide analogue therapy with TDF or LDT throughout pregnancy had no effect on the long-term physical development and bone development of children. In addition, the use of TDF throughout pregnancy had better long-term antiviral efficacy than LDT in women, with no evidence of renal toxicity.

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.

Pre-treatment with Beta Carotene Gives Protection Against Nephrotoxicity Induced by Bromobenzene via Modulation of Antioxidant System, Pro-inflammatory Cytokines and Pro-apoptotic Factors

Bromobenzene is an environmental toxin which causes hepatotoxicity, and the secondary metabolites on biotransformation cause nephrotoxicity. The objective of this study was to assess the alleviation of the nephrotoxic effect of bromobenzene by beta carotene in female Wistar albino rats. Beta carotene (10 mg/kg b.w.p.o.) was delivered orally to the rats for 9 days before bromobenzene (10 mM/kg b.w.p.o.) was intragastrically intubated. Kidney markers, antioxidant status and lipid peroxidation were evaluated. In addition, the levels of TNF-α, IL-6 and IL-1β were measured in serum and in kidney tissue homogenate using ELISA. Caspase, COX-2 and NF-κB were measured with the help of Western blotting. Histopathological analysis of the kidney was done for the control and experimental rats. Bromobenzene induction caused elevation in levels of creatinine, urea, uric acid, cytokines and lipid per oxidation along with deterioration in histological observations and antioxidant status. Pre-treatment with beta carotene significantly (*p < 0.05) normalised the levels of kidney markers and pro-inflammatory cytokines. It also reduced oxidative stress and lipid peroxidation, as shown by improved antioxidant status. The anti-apoptotic activity was evidenced by inhibition of protein expression of caspase, COX-2 and NF-κB. This significant reversal (*p < 0.05) of the above variations in comparison with the control group as noticed in the bromobenzene-administered rats demonstrates that beta carotene possesses promising nephroprotective effect through its antioxidant, anti-inflammatory and anti-apoptotic activity and therefore suggests its use as a potential therapeutic agent for protection from bromobenzene and hence environmental pollutant toxicity.

The footprints of mitochondrial impairment and cellular energy crisis in the pathogenesis of xenobiotics-induced nephrotoxicity, serum electrolytes imbalance, and Fanconi's syndrome: A comprehensive review

Fanconi's Syndrome (FS) is a disorder characterized by impaired renal proximal tubule function. FS is associated with a vast defect in the renal reabsorption of several chemicals. Inherited and/or acquired conditions seem to be connected with FS. Several xenobiotics including many pharmaceuticals are capable of inducing FS and nephrotoxicity. Although the pathological state of FS is well described, the exact underlying etiology and cellular mechanism(s) of xenobiotics-induced nephrotoxicity, serum electrolytes imbalance, and FS are not elucidated. Constant and high dependence of the renal reabsorption process to energy (ATP) makes mitochondrial dysfunction as a pivotal mechanism which could be involved in the pathogenesis of FS. The current review focuses on the footprints of mitochondrial impairment in the etiology of xenobiotics-induced FS. Moreover, the importance of mitochondria protecting agents and their preventive/therapeutic capability against FS is highlighted. The information collected in this review may provide significant clues to new therapeutic interventions aimed at minimizing xenobiotics-induced renal injury, serum electrolytes imbalance, and FS.

The Changing Face of Human Immunodeficiency Virus-Mediated Kidney Disease

In nearly 40 years since human immunodeficiency virus (HIV) first emerged, much has changed. Our understanding of the pathogenesis of HIV infection and its effect on the cells within each kidney compartment has progressed, and the natural history of the disease has been transformed. What was once an acutely fatal illness is now a chronic disease managed with oral medications. This change is largely due to the advent of antiretroviral drugs, which have dramatically altered the prognosis and progression of HIV infection. However, the success of antiretroviral therapy has brought with it new challenges for the nephrologist caring for patients with HIV/acquired immune deficiency syndrome, including antiretroviral therapy-induced nephrotoxicity, development of non-HIV chronic kidney disease, and rising incidence of immune-mediated kidney injury. In this review, we discuss the pathogenesis of HIV infection and how it causes pathologic changes in the kidney, review the nephrotoxic effects of select antiretroviral medications, and touch upon other causes of kidney injury in HIV cases, including mechanisms of acute kidney injury, HIV-related immune complex glomerular disease, and thrombotic microangiopathy.

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

Tenofovir disoproxil fumarate (TDF) is currently the only nucleotide analogue reverse-transcriptase inhibitor that is approved by the Food and Drug administration (FDA), USA, for the treatment of human immunodeficiency virus (HIV) infection. In recent days, renal toxicity is becoming common i HIV patients treated with TDF. However, the mechanism of tenofovir nephrotoxicity is not clear. We hypothesized that mitochondrial pathway of apoptosis, poly [ADP-ribose] polymerase (PARP) overactivation and neutrophil infiltration may contribute to tenofovir-induced renal damage. Renal damage was induced in adult male Wistar rats by the oral administration of 600 mg/kg body weight daily for five consecutive weeks. Kidneys were removed and used for histological and biochemical analyses. Apoptosis was detected by terminal deoxynucleotidyl transferase biotin-deoxyuridine triphosphate nick end-labelling (TUNEL) assay and caspase 3 activity and protein expression; mitochondrial pathway of apoptosis by cyt c release; and PARP activation by immunofluorescence, immunohistochemistry and Western blot techniques. Myeloperoxidase (MPO) activity was measured as a marker of neutrophil infiltration. TDF administration resulted in increased number of TUNEL-positive cells, activation of caspase 3 and release of cyt c from mitochondria into the cytosol in the kidneys. There was increased nuclear localization of PARP as well as increase in its protein level in the TDF-treated rat kidneys. In addition, renal MPO activity was increased ninefold as compared to controls. The results of the present study show that mitochondrial apoptotic pathway, PARP overactivation and neutrophil infiltration contribute to tenofovir-induced renal damage in rats.

Combination ART-Induced Oxidative/Nitrosative Stress, Neurogenic Inflammation and Cardiac Dysfunction in HIV-1 Transgenic (Tg) Rats: Protection by Mg

Chronic effects of a combination antiretroviral therapy (cART = tenofovir/emtricitatine + atazanavir/ritonavir) on systemic and cardiac oxidative stress/injury in HIV-1 transgenic (Tg) rats and protection by Mg-supplementation were assessed. cART (low doses) elicited no significant effects in normal rats, but induced time-dependent oxidative/nitrosative stresses: 2.64-fold increased plasma 8-isoprostane, 2.0-fold higher RBC oxidized glutathione (GSSG), 3.2-fold increased plasma 3-nitrotyrosine (NT), and 3-fold elevated basal neutrophil superoxide activity in Tg rats. Increased NT staining occurred within cART-treated HIV-Tg hearts, and significant decreases in cardiac systolic and diastolic contractile function occurred at 12 and 18 weeks. HIV-1 expression alone caused modest levels of oxidative stress and cardiac dysfunction. Significantly, cART caused up to 24% decreases in circulating Mg in HIV-1-Tg rats, associated with elevated renal NT staining, increased creatinine and urea levels, and elevated plasma substance P levels. Strikingly, Mg-supplementation (6-fold) suppressed all oxidative/nitrosative stress indices in the blood, heart and kidney and substantially attenuated contractile dysfunction (>75%) of cART-treated Tg rats. In conclusion, cART caused significant renal and cardiac oxidative/nitrosative stress/injury in Tg-rats, leading to renal Mg wasting and hypomagnesemia, triggering substance P-dependent neurogenic inflammation and cardiac dysfunction. These events were effectively attenuated by Mg-supplementation likely due to its substance P-suppressing and Mg’s intrinsic anti-peroxidative/anti-calcium properties.

Klotho ameliorates hydrogen peroxide-induced oxidative injury in TCMK-1 cells

PURPOSE

Defects in Klotho gene expression in mice result in a vulnerability to oxidative injuries. We aimed to identify the expression of Klotho in a mouse tubular epithelial (TCMK-1) cell line, and also to investigate changes in Klotho expression induced by oxidative stress and the potential role of intra- and extracellular Klotho protein.

METHODS

During exposure to hydrogen peroxide (H₂O₂), an overexpression of the Klotho gene was induced and exogenous Klotho protein was added in TCMK-1 cells. The generation of reactive oxidative species (ROS) was examined by flow cytometry, and cell viability was assessed by Cell Counting Kit-8. Cellular apoptosis was determined by flow cytometry and Hoechst 33258 staining followed by Western blotting to evaluate the expression of Klotho, antioxidant enzymes, and apoptosis-associated proteins.

RESULTS

While H₂O₂ significantly suppressed Klotho expression, cell viability, and the expression of antioxidant enzymes in a concentration-dependent manner, cellular apoptosis was increased and p38/MAPK and JNK/MAPK were activated. Intra- and extracellular Klotho remarkably ameliorated viability inhibition, ROS generation, and cellular apoptosis induced by H₂O₂. Intra- and extracellular Klotho also reversed the loss of antioxidant enzymes, the elevation of cleaved Caspase-3 and Bax/Bcl-2, and the phosphorylation of JNK/MAPK and p38/MAPK.

CONCLUSIONS

Klotho has posed antioxidant and anti-apoptotic effects on oxidative injuries in TCMK-1 cells, which might be partially related to its inhibition of JNK/MAPK and p38/MAPK phosphorylation and subsequent elevation of antioxidant enzymes. Increasing Klotho expression has played a protective role against oxidative stress in tubular epithelial cells.

Changes in Kidney Function and in the Rate of Tubular Dysfunction After Tenofovir Withdrawal or Continuation in HIV-Infected Patients

INTRODUCTION

Longitudinal data on the changes in kidney function and tubular abnormalities in case of tenofovir disoproxil fumarate (TDF) withdrawal or continuation are scarce.

METHODS

Prospective study of 228 patients receiving TDF, with 3 sequential determinations of serum creatinine, estimated glomerular filtration rate (eGFR), phosphatemia, and different urinary parameters (protein, albumin, phosphaturia, uricosuria, and glycosuria). Changes were analyzed in patients who interrupted TDF as compared to those who continued the same regimen. Proximal renal tubular dysfunction (PRTD) was defined as ≥2 tubular abnormalities.

RESULTS

After a median follow-up of 59.5 months, 78 patients (34%) had PRTD, mainly proteinuria (40%) and phosphaturia (61%), and time on TDF explains the severity of tubular alterations and eGFR slopes. In 35 switching patients, there was a rapid and significant eGFR improvement (median +4.1 ml/min per 1.73 m; P = 0.02), leading to a 39%-83% reduction in the prevalence of tubular abnormalities and of PRTD in less than 1 year (66%-39%). In comparison, 193 patients continuing the same regimen for 21.2 months had a small but significant and progressive eGFR decrease (-2.9 mL·min·1.73 m; P < 0.01), and a progressive rise in the prevalence of phosphaturia, uricosuria, and glycosuria (+9%-56%). In linear mixed-effect model, subsequent eGFR impairment was associated with proteinuria and time on TDF, and eGFR improvement with TDF discontinuation.

CONCLUSIONS

Our data support the role of use and time on TDF in eGFR decline and tubular dysfunction. In contrast, TDF withdrawal is followed by a rapid and significant, although partial, recovery of eGFR and tubular abnormalities.

Tenofovir-induced toxicity in renal proximal tubular epithelial cells: involvement of mitochondria

OBJECTIVE

In-vivo studies suggest that mitochondria is involved in tenofovir (TFV)-induced renal toxicity, but the underlying mechanisms are still unclear. The aim of the present study was to assess the effects of TFV and its prodrug, TFV disoproxil fumarate, on mitochondrial function and cell survival/viability in a renal proximal tubular cell line.

DESIGN AND METHODS

We evaluated parameters of cellular proliferation/survival (cell count, cell cycle, viability) and mitochondrial function (oxygen consumption, mitochondrial membrane potential, reactive oxygen species production) in NRK-52E cells. Intracellular TFV was measured by HPLC and expression of antioxidant genes was analysed by real-time PCR.

RESULTS

Similar intracellular levels of TFV were reached with lower concentrations of the prodrug than of the drug, and correlated directly with a decrease in cell number. Both compounds inhibited proliferation and compromised mitochondrial function by decreasing mitochondrial membrane potential and increasing oxygen consumption and mitochondrial superoxide production. Altered oxidative status was confirmed by the overexpression of antioxidant genes.

CONCLUSIONS

Intracellular accumulation of TFV induces mitochondrial toxicity in an in-vitro renal model and alters cell proliferation and viability. Our findings call for caution regarding the use of this nucleotide analogue reverse transcriptase inhibitor in patients with other risk factors that compromise mitochondrial function in the kidney.

Tenofovir and adefovir down-regulate mitochondrial chaperone TRAP1 and succinate dehydrogenase subunit B to metabolically reprogram glucose metabolism and induce nephrotoxicity

Despite the therapeutic success of tenofovir (TFV) for treatment of HIV-1 infection, numerous cases of nephrotoxicity have been reported. Mitochondrial toxicity has been purported as the major target of TFV-associated renal tubulopathy but the underlying molecular mechanism remains unclear. In this report, we use metabolomics and proteomics with HK-2 cells and animal models to dissect the molecular pathways underlying nephropathy caused by TFV and its more toxic analog, adefovir (ADV). Proteomic analysis shows that mitochondrial chaperone TRAP1 and mtDNA replicating protein SSBP1 were significantly down-regulated in TFV and ADV treated HK-2 cells compared with controls. Transmission electron microscopy (TEM) revealed that TFV and ADV-treated HK-2 cells had accumulated glycogen, a phenotype that was also observed in mice treated with TFV and ADV. Analysis of the proteins in TCA cycle showed succinate dehydrogenase subunit B (SDHB) was nearly depleted in glucose oxidative phosphorylation pathway however certain enzymes in the glycolysis and glycogen synthesis pathway had elevated expression in TFV and ADV-treated HK-2 cells. These results suggest that TFV and ADV may cause mitochondrial dysfunction in renal tubular cells and reprogramming of glucose metabolism. The resulting glycogen accumulation may partially contribute to TFV and ADV induced renal dysfunction.

Evaluation of abrin induced nephrotoxicity by using novel renal injury markers

Abrin is a potent plant toxin analogous to ricin that is derived from the seeds of Abrus precatorius plant. It belongs to the family of type II ribosome-inactivating proteins and causes cell death by irreversibly inactivating ribosomes through site-specific depurination. In this study we examined the in vivo nephrotoxicity potential of abrin toxin in terms of oxidative stress, inflammation, histopathological changes and biomarkers of kidney injury. Animals were exposed to 0.5 and 1.0 LD50 dose of abrin by intraperitoneal route and observed for 1, 3, and 7 day post-toxin exposure. Depletion of reduced glutathione and increased lipid peroxidation levels were observed in abrin treated mice. In addition, abrin also induced inflammation in the kidneys as observed through expression of MMP-9 and MMP-9/NGAL complex in abrin treated groups by using zymography method. Nephrotoxicity was also evaluated by western blot analysis of kidney injury biomarkers including Clusterin, Cystatin C and NGAL, and their results indicate severity of kidney injury in abrin treated groups. Kidney histology confirmed inflammatory changes due to abrin. The data generated in the present study clearly prove the nephrotoxicity potential of abrin.

Establishment of HK-2 Cells as a Relevant Model to Study Tenofovir-Induced Cytotoxicity

Tenofovir (TFV) is an antiviral drug approved for treating Human Immunodeficiency Virus (HIV) and Hepatitis B. TFV is administered orally as the prodrug tenofovir disoproxil fumarate (TDF) which then is deesterified to the active drug TFV. TFV induces nephrotoxicity characterized by renal failure and Fanconi Syndrome. The mechanism of this toxicity remains unknown due to limited experimental models. This study investigated the cellular mechanism of cytotoxicity using a human renal proximal tubular epithelial cell line (HK-2). HK-2 cells were grown for 48 h followed by 24 to 72 h exposure to 0–28.8 μM TFV or vehicle, phosphate buffered saline (PBS). MTT (MTT, 3-(4,5-dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide) and Trypan blue indicated that TFV diminished cell viability at 24–72 h. TFV decreased ATP levels at 72 h when compared to vehicle, reflecting mitochondrial dysfunction. TFV increased the oxidative stress biomarkers of protein carbonylation and 4-hydroxynonenol (4-HNE) adduct formation. Tumor necrosis factor alpha (TNFα) was released into the media following exposure to 14.5 and 28.8 μM TFV. Caspase 3 and 9 cleavage was induced by TFV compared to vehicle at 72 h. These studies show that HK-2 cells are a sensitive model for TFV cytotoxicity and suggest that mitochondrial stress and apoptosis occur in HK-2 cells treated with TFV.

The efficacy and safety of tenofovir alafenamide versus tenofovir disoproxil fumarate in antiretroviral regimens for HIV-1 therapy: Meta-analysis

BACKGROUND

To date, a definite conclusion about efficiency and safety of tenofovir alafenamide for patients with HIV-1 is not available. The aim of the study was to investigate the efficacy and safety of TAF versus TDF in antiretroviral regimens for patients with HIV-1.

METHODS

PUBMED, MEDLINE, and EMBASE database were searched in March 2016, with no language restriction, for randomized controlled trials (RCTs).

RESULTS

Six RCTs (n = 5888) met entry criteria. At week 48, viral suppression rates were similar between TAF and TDF group (90.2% vs 89.5%) for the naive patients. Interestingly, the rate was higher in patients who switched to TAF regimens compared with patients who continued previous TDF regimens (96.4% vs 93.1%). Both groups were generally well tolerated with high barrier to resistance. As compared to TDF, TAF had significantly smaller reductions in eGFR-CG, smaller changes in RBP/Cr and urineβ-2 M/Cr ratio, and less reduction in spine and hip BMD for the treatment-naive patients. Moreover, the switched group had significant efficacy advantages of improving renal function and BMD, including significant decreases in urine albumin/Cr, urine protein/Cr, urine RBP/Cr, and urine β-2 M/Cr ratios, and increases in hip and spine BMD by 1.47% and 1.56%,respectively, as compared with continued TDF regimens.

CONCLUSIONS

TAF has a similar tolerability, safety, and effectiveness to TDF and probably less adverse events related to renal and bone density outcomes in the treatment of naive and experienced patients with HIV-1.

Higher tenofovir exposure is associated with longitudinal declines in kidney function in women living with HIV

OBJECTIVE

Tenofovir disoproxil fumarate is a commonly used antiretroviral drug, but risk factors for tenofovir (TFV)-associated kidney disease are not fully understood. We used intensive pharmacokinetic studies in a cohort of HIV-infected women on TFV-based therapy to study the relationship between TFV exposure and subsequent kidney function.

DESIGN

This is a nested study within the Women's Interagency HIV Study, a multicenter, prospective cohort of HIV-infected women. Participants on TFV-based therapy underwent 24-h intensive pharmacokinetic sampling after witnessed dose. Kidney function was measured over the succeeding 7 years by serum creatinine [estimated glomerular filtration rate calculated by serum creatinine (eGFRcr)].

METHODS

Multivariable linear mixed models evaluated the relationship of baseline TFV area under the-time concentration curves (AUCs) with subsequent changes in kidney function. Covariates included age, diabetes, hypertension, race, BMI, ritonavir use, duration of TFV exposure, current CD4 cell count, and HIV viral load.

RESULTS

Of the 105 participants, persons within the highest baseline TFV AUC tertile had significantly lower eGFRcr compared with those in the lowest tertile (mean ± standard error: 80 ± 4.3 vs. 104 ± 2.5 ml/min per 1.73 m, P < 0.0001). By year 7, this difference widened (72 ± 4.9 vs. 105 ± 2.9, P < 0.0001). After multivariable adjustment, TFV AUC in the highest tertile remained associated with lower eGFRcr relative to values in the lowest tertile at both baseline (-15 ml/min per 1.73 m, P = 0.0047) and year 7 (-23 ml/min per 1.73 m, P = 0.0002).

CONCLUSION

Through intensive TFV pharmacokinetic sampling, we found a strong association between greater TFV exposure and subsequent decline in kidney function. Variations in TFV drug exposure may partially account for subsequent nephrotoxicity in persons infected with HIV.

Is Abnormal Urine Protein/Osmolality Ratio Associated with Abnormal Renal Function in Patients Receiving Tenofovir Disoproxil Fumarate?

BACKGROUND

Risk factors for and optimal surveillance of renal dysfunction in patients on tenofovir disoproxil fumarate (TDF) remain unclear. We investigated whether a urine protein-osmolality (P/O) ratio would be associated with renal dysfunction in HIV-infected persons on TDF.

METHODS

This retrospective, single-center study investigated the relationship between parameters of renal function (estimated glomerular filtration rate (eGFR) and P/O-ratio) and risk factors for development of kidney dysfunction. Subjects were HIV-infected adults receiving TDF with at least one urinalysis and serum creatinine performed between 2010 and 2013. Regression analyses were used to analyze risk factors associated with abnormal P/O-ratio and abnormal eGFR during TDF therapy.

RESULTS

Patients were predominately male (81%); (65%) were Caucasian. Mean age was 45.1(±11.8) years; median [IQR] TDF duration was 3.3 years. [1.5-7.6]. Median CD4+ T cell count and HIV viral load were 451 cells/μL [267.5-721.5] and 62 copies/mL [0-40,150], respectively. Abnormal P/O-ratio was not associated with low eGFR. 68% of subjects had an abnormal P/O-ratio and 9% had low eGFR. Duration of TDF use, age, diabetes and hypertension were associated with renal dysfunction in this study. After adjustment for age, subjects on TDF > 5 years had almost a four-fold increased likelihood of having an abnormal P/O-ratio than subjects on TDF for < 1yr (OR 3.9; 95% CI 1.2-14.0; p = 0.024).

CONCLUSION

Abnormal P/O-ratio is common in HIV-infected patients on TDF but was not significantly associated with low eGFR, suggesting that abnormal P/O-ratio may be a very early biomarker of decreased renal function in HIV infected patients.

Effects of antipsychotic drug administration on antioxidative defense enzymes in male rat kidney

The use of atypical antipsychotic drugs (APD) was reported to be associated with adverse effects on the kidneys. Thus, the aim of this study was to examine whether APD exerted their adverse effects by interfering with the renal antioxidant defense system. Male 3-mo-old Wistar rats were treated for 28 d with ziprasidone (ZIP), clozapine (CLO), or sertindole (SER) using a daily dose recommended for antipsychotic drug therapy. The expression and activities of antioxidant enzymes superoxide dismutase (SOD) type 1 and type 2, catalase (CAT), glutathione reductase (GR), and glutathione S-transferases (GSTs) activity were measured in the kidneys. Changes in the kidneys were also evaluated histologically. Ziprasidone, CLO, and SER reduced renal SOD type 1 and type 2 activities. Decreased CAT activity was observed only in SER-treated rats. An inhibition in GR activity and increased activity of GST was found only after treatment with CLO. Histological analysis showed dilatation of proximal tubules in kidneys with all three drugs. In conclusion, data indicate that redox disturbances may contribute to renal morphologic alterations in proximal tubules in rats treated with all APD.

Drug-induced Fanconi syndrome associated with fumaric acid esters treatment for psoriasis: a case series

BACKGROUND

Fumaric acid esters (FAEs), an oral immunomodulating treatment for psoriasis and multiple sclerosis, have been anecdotally associated with proximal renal tubular dysfunction due to a drug-induced Fanconi syndrome. Few data are available on clinical outcomes of FAE-induced Fanconi syndrome.

METHODS

Descriptive case series with two cases of Fanconi syndrome associated with FAE treatment diagnosed at two Dutch university nephrology departments, three cases reported at the Dutch and German national pharmacovigilance databases and six previously reported cases.

RESULTS

All 11 cases involved female patients with psoriasis. The median age at the time of onset was 38 years [interquartile range (IQR) 37-46]. Patients received long-term FAEs treatment with a median treatment duration of 60 months (IQR 28-111). Laboratory tests were typically significant for low serum levels of phosphate and uric acid, while urinalysis showed glycosuria and proteinuria. Eight (73%) patients had developed a hypophosphataemic osteomalacia and three (27%) had pathological bone fractures. All patients discontinued FAEs, while four (36%) patients were treated with supplementation of phosphate and/or vitamin D. Five (45%) patients had persisting symptoms despite FAEs discontinuation.

CONCLUSIONS

FAEs treatment can cause drug-induced Fanconi syndrome, but the association has been reported infrequently. Female patients with psoriasis treated long term with FAEs seem to be particularly at risk. Physicians treating patients with FAEs should be vigilant and monitor for the potential occurrence of Fanconi syndrome. Measurement of the urinary albumin:total protein ratio is a suggested screening tool for tubular proteinuria in Fanconi syndrome.

Tenofovir disoproxil fumarate: toxicity, toxicokinetics, and toxicogenomics analysis after 13 weeks of oral administration in mice

Tenofovir disoproxil fumarate (TDF) is a prodrug of tenofovir that exhibits activity against HIV and hepatitis B. The goals of this study were to evaluate the molecular mechanism of TDF-induced toxicity in mice after 13 weeks of daily oral administration (50-1000 mg/kg) by correlating transcriptional changes with plasma drug levels and traditional toxicology end points. Plasma levels and systemic exposure of tenofovir increased less than dose proportionally and were similar on days 1 and 91. No overt toxicity was observed following the completion of TDF administration. The kidneys of TDF-treated mice were histopathologically normal. This result is consistent with the genomic microarray results, which showed no significant differences in kidney transcriptional levels between TDF-treated animals and controls. In liver, after 4 and 13 weeks, cytomegaly was observed in mice treated with 1000 mg/kg of TDF, but mice recovered from this effect following cessation of administration. Analysis of liver transcripts on day 91 reported elevated levels of Cdkn1a in TDF-treated animals compared with controls, which may have contributed to the inhibition of liver cell cycle progression.

Overexpression of mitochondrial antioxidant manganese superoxide dismutase (MnSOD) provides protection against AZT- or 3TC-induced endothelial dysfunction

Nucleoside reverse transcriptase inhibitors (NRTIs) are considered the backbone of current combination therapies for HIV. These therapies have significantly decreased mortality and morbidity in HIV-infected patients, but some are associated with cardiovascular complications, including endothelial dysfunction, an early marker for atherosclerosis. Our prior studies demonstrated that co-treatment of cells with an antioxidant therapy reversed NRTI-induced endothelial injury. Thus, as a proof of concept that mitochondrially-targeted antioxidants may be useful in preventing NRTI toxicity, in the current study, mice overexpressing a mitochondrial antioxidant, manganese superoxide dismutase (MnSOD), were compared with wild-type (WT) mice. Mice were treated chronically with either zidovudine (AZT), lamivudine (3TC), or tenofovir (TDF) to determine whether overexpression of MnSOD protected them from endothelial dysfunction. Endothelial function was assessed using vessel reactivity experiments on thoracic aortas as well as measures of endothelium derived factors nitric oxide (NO), endothelin-1 (ET-1), and prostacyclin. Oxidative stress was evaluated as levels of plasma 8-isoprostane. Alterations in vessel reactivity, NO, and ET-1 in WT mice treated with AZT or 3TC were noted. Overexpression of MnSOD offered protection from decreases in vessel reactivity and increases in ET-1. These findings indicate that mitochondrial oxidative stress induced by AZT or 3TC plays a major role in mediating NRTI-induced endothelial dysfunction, and suggest that the use of targeted antioxidants administered in conjunction with NRTIs may attenuate these effects.

Mitochondria-targeted therapies for acute kidney injury

Acute kidney injury (AKI) is a serious clinical condition with no effective treatment. Tubular cells are key targets in AKI. Tubular cells and, specifically, proximal tubular cells are extremely rich in mitochondria and mitochondrial changes had long been known to be a feature of AKI. However, only recent advances in understanding the molecules involved in mitochondria biogenesis and dynamics and the availability of mitochondria-targeted drugs has allowed the exploration of the specific role of mitochondria in AKI. We now review the morphological and functional mitochondrial changes during AKI, as well as changes in the expression of mitochondrial genes and proteins. Finally, we summarise the current status of novel therapeutic strategies specifically targeting mitochondria such as mitochondrial permeability transition pore (MPTP) opening inhibitors (cyclosporine A (CsA)), quinone analogues (MitoQ, SkQ1 and SkQR1), superoxide dismutase (SOD) mimetics (Mito-CP), Szeto-Schiller (SS) peptides (Bendavia) and mitochondrial division inhibitors (mdivi-1). MitoQ, SkQ1, SkQR1, Mito-CP, Bendavia and mdivi-1 have improved the course of diverse experimental models of AKI. Evidence for a beneficial effect of CsA on human cardiac ischaemia-reperfusion injury derives from a clinical trial; however, CsA is nephrotoxic. MitoQ and Bendavia have been shown to be safe for humans. Ongoing clinical trials are testing the efficacy of Bendavia in AKI prevention following renal artery percutaneous transluminal angioplasty.

Sex hormones regulate tenofovir-diphosphate in female reproductive tract cells in culture

The conflicting results of recent pre-exposure prophylaxis (PrEP) trials utilizing tenofovir (TFV) to prevent HIV infection in women led us to evaluate the accumulation of intracellular TFV-diphosphate (TFV-DP) in cells from the female reproductive tract (FRT) and whether sex hormones influence the presence of TFV-DP in these cells. Following incubation with TFV, isolated epithelial cells, fibroblasts, CD4+ T cells and CD14+ cells from the FRT as well as blood CD4+ T cells and monocyte-derived macrophages convert TFV to TFV-DP. Unexpectedly, we found that TFV-DP concentrations (fmol/million cells) vary significantly with the cell type analyzed and the site within the FRT. Epithelial cells had 5-fold higher TFV-DP concentrations than fibroblasts; endometrial epithelial cells had higher TFV-DP concentrations than cells from the ectocervix. Epithelial cells had 125-fold higher TFV-DP concentrations than FRT CD4+ T cells, which were comparable to that measured in peripheral blood CD4+ T cells. These findings suggest the existence of a TFV-DP gradient in the FRT where epithelial cells > fibroblasts > CD4+ T cells and macrophages. In other studies, estradiol increased TFV-DP concentrations in endometrial and endocervical/ectocervical epithelial cells, but had no effect on fibroblasts or CD4+ T cells from FRT tissues. In contrast, progesterone alone and in combination with estradiol decreased TFV-DP concentrations in FRT CD4+ T cells. Our results suggest that epithelial cells and fibroblasts are a repository of TFV-DP that is under hormonal control. These cells might act either as a sink to decrease TFV availability to CD4+ T cells and macrophages in the FRT, or upon conversion of TFV-DP to TFV increase TFV availability to HIV-target cells. In summary, these results indicate that intracellular TFV-DP varies with cell type and location in the FRT and demonstrate that estradiol and/or progesterone regulate the intracellular concentrations of TFV-DP in FRT epithelial cells and CD4+ T cells.

Tenofovir-induced nephrotoxicity: incidence, mechanism, risk factors, prognosis and proposed agents for prevention

OBJECTIVE

In this study, data regarding epidemiology, risk factors, pathogenesis and outcome of tenofovir-induced nephrotoxicity will be reviewed, and current and future approaches for prevention will be discussed.

METHOD

The data were collected by searching Scopus, PubMed, Medline, Science direct, Clinical trials and Cochrane database systematic reviews. The keywords used as search terms were "Tenofovir", "TDF", "NRTI", "Nephrotoxicity", "Renal failure", "Kidney damage", "HIV" and "AIDS".

RESULTS AND CONCLUSION

Several predisposing factors including elevated baseline SCr, concomitant nephrotoxic medications, low body weight, advanced age, tenofovir disoproxil fumarate (TDF) dose and duration of treatment and lower CD4 cell count were identified as risk factors for development of TDF-induced nephrotoxicity. Cellular accumulation through increased entry from the human organic anion transporters and decreased efflux into tubular lumen is main mechanism of nucleotide analogue antiviral induced nephrotoxicity. Renal function assessment and monitoring at baseline and during TDF treatment are the main approach of prevention of TDF-induced nephrotoxicity. Rosiglitazone may be helpful in patients presenting with TDF-induced nephrotoxicity. Pretreatment with melatonin prevented all known histological changes in proximal tubular mitochondira induced by TDF. Use of antioxidants with mitochondria-targeted properties such as MitoQ or Mito-CP may prevent proximal tubular mitochondrial against TDF damage. Vitamin E, ebselen, lipoic acid, plastoquinone, nitroxides, SOD enzyme mimetics, Szeto-Schiller (SS) peptides, and quercetin are other potential agents for prevention of TDF-induced nephrotoxicity. However, data regarding effectiveness of nephroprotective agents against TDF-induced nephrotoxicity are not conclusive. Before extrapolation of the preclinical evidence to clinical practice, these evidence should be confirmed in future human studies.

Nonclinical Safety Profile of BMS-986001, a Nucleoside Transcriptase Inhibitor for Combination Retroviral Therapy

Nucleoside reverse transcriptase inhibitors (NRTIs)/nucleotide reverse transcriptase inhibitors are key components of combination antiretroviral therapy for HIV infection. First-generation NRTIs are associated with mitochondrial toxicity in patients, mainly due to inhibition of human DNA polymerase γ (hDNA polγ) that manifests as adverse events such as lipodystrophy, lactic acidosis, myopathy, cardiomyopathy, or nephropathy in patients. In chronic nonclinical studies in rodents and nonrodents, eukaryotic (host) mitochondrial toxicity manifests as some drug-specific toxicities similar to human toxicity. BMS-986001, a novel thymidine analog with minimal hDNA polγ inhibition, has demonstrated antiretroviral activity in early clinical studies. The primary toxicity of BMS-986001 in rats and monkeys is bone marrow dyserythropoiesis with associated decreases in red blood cell mass. Additionally, at high doses, severe platelet reductions accompanied by cutaneous petechiae began during weeks 8 and 11 in 3 of 60 monkeys in chronic toxicity studies. In a 6-month study, platelet reductions required euthanasia of the 2 affected monkeys (300 mg/kg/d) at week 14, but with dose reduction (200 mg/kg/d) remaining monkeys had no platelet changes. One affected monkey (200 mg/kg/d) in a 9-month study completed dosing and its platelet counts recovered during a 1-month recovery. Formation of platelet-bound immunoglobulin in the presence of BMS-986001, together with rapid and complete platelet recovery in the absence of BMS-986001, suggested that platelet decreases in monkeys may be immune mediated. No findings indicative of mitochondrial toxicity were observed in rats or monkeys given BMS-986001, suggesting an improved safety profile compared to marketed NRTI or tenofovir disoproxil fumarate.