Molecular-targeted approaches to reduce renal accumulation of nephrotoxic drugs

Ceratonia siliqua pods (Carob) methanol extract alleviates doxorubicin-induced nephrotoxicity via antioxidant, anti-inflammatory and anti-apoptotic pathways in rats

Doxorubicin (DOX) is an anti-neoplastic therapy, but its use is limited by its deleterious toxic effects including nephrotoxicity and cardiotoxicity. This work aimed at assessing the potential protective effect of Ceratonia siliqua methanol extract (CME) on DOX-induced nephrotoxicity in 5 groups of Wistar rats. Nephrotoxicity was induced experimentally by intraperitoneal (IP) injection of DOX (15 mg/kg). DOX increased serum creatinine, urea, sodium, and potassium levels. It elevated MDA levels in the renal tissue but decreased the concentration of GSH and the activity of GST, CAT, and SOD. Meanwhile, it decreased the level of immunomodulatory anti-inflammatory mediators: IL-10 and TGF-β, as well as the activity of MPO but increased the level of IL-6, TNF-α, and caspase-3 in the renal tissue. DOX has upregulated COX-2, caspase-9, and Bax gene expression and downregulated the Bcl-2 gene expression. Immunolabeling of renal tubular epithelium in DOX-intoxicated rats was moderate to strong against Bax, COX-2, and NF-kβ and weak against Bcl-2. Treatment with CME significantly restored the levels of kidney function parameters and the levels of oxidative stress markers. It stimulated the production of IL-10 and TGF-β and decreased the level of IL-6 and TNF-α. CME reverted the gene expression of COX-2, caspase-9, and Bax. Microscopically, CME alleviated the DOX-induced renal damage. Phytochemical analysis revealed the presence of 26 compounds in the CME. No signs of acute toxicity were recorded by CME up to 4000 mg/kg b. wt. orally into mice. Finally, CME could effectively alleviate the deleterious effects of DOX on the kidney. The safety of carob extract encourages its use in the preparation of valuable therapeutic agents.

Flavonoids of Haloxylon salicornicum (Rimth) prevent cisplatin-induced acute kidney injury by modulating oxidative stress, inflammation, Nrf2, and SIRT1

Cisplatin (CIS) is an effective chemotherapeutic drug used for the treatment of many types of cancers, but its use is associated with adverse effects. Nephrotoxicity is a serious side effect of CIS and limits its therapeutic utility. Haloxylon salicornicum is a desert shrub used traditionally in the treatment of inflammatory disorders, but neither its flavonoid content nor its protective efficacy against CIS nephrotoxicity has been investigated. In this study, seven flavonoids were isolated from H. salicornicum methanolic extract (HSE) and showed in silico binding affinity with NF-κB, Keap1, and SIRT1. The protective effect of HSE against CIS nephrotoxicity was investigated. Rats received HSE (100, 200, and 400 mg/kg) for 14 days followed by a single injection of CIS. The drug increased Kim-1, BUN, and creatinine and caused multiple histopathological changes. CIS-administered rats showed an increase in renal ROS, MDA, NO, TNF-α, IL-1β, and NF-κB p65. HSE prevented tissue injury, and diminished ROS, NF-κB, and inflammatory mediators. HSE enhanced antioxidants and Bcl-2 and downregulated pro-apoptosis markers. These effects were associated with downregulation of Keap1 and microRNA-34a, and upregulation of SIRT1 and Nrf2/HO-1 signaling. In conclusion, H. salicornicum is rich in flavonoids, and its extract prevented oxidative stress, inflammation, and kidney injury, and modulated Nrf2/HO-1 and SIRT1 signaling in CIS-treated rats.

7-hydroxycoumarin modulates Nrf2/HO-1 and microRNA-34a/SIRT1 signaling and prevents cisplatin-induced oxidative stress, inflammation, and kidney injury in rats

The kidneys are vulnerable to toxicity and acute kidney injury (AKI) is the main adverse effect associated with the clinical use of the chemotherapeutic agent cisplatin (CIS). Oxidative stress and inflammation are implicated in CIS nephrotoxicity. In this study, the effect of the antioxidant 7-hydroxycoumarin (7-HC) against CIS-induced renal intoxication was evaluated. Rats received 7-HC (25, 50, and 100 mg/kg) orally for 14 days and CIS (7 mg/kg) at day 15, and samples were collected 3 days after CIS administration. CIS increased serum urea, creatinine and kidney injury molecule (Kim)-1, caused multiple histopathological changes and increased renal reactive oxygen species (ROS), malondialdehyde (MDA), nitric oxide (NO), NF-κB p65, iNOS, and pro-inflammatory cytokines. 7-HC dose-dependently prevented kidney dysfunction and tissue injury and suppressed ROS and inflammatory mediators. 7-HC boosted renal antioxidants and Bcl-2 while decreased Bax and caspase-3 expression in CIS-administered rats. In addition, 7-HC downregulated Keap-1 and microRNA-34a and upregulated Nrf2, NQO-1, HO-1, and SIRT1. Molecular docking revealed the binding affinity of 7-HC towards NF-κB, Keap-1, and SIRT1. In Conclusion, 7-HC prevented CIS nephrotoxicity by attenuating tissue injury, oxidative stress, inflammation, and apoptotic cell death. The protective efficacy of 7-HC was associated with inhibiting NF-κB and Keap-1, and modulating Nrf2/HO-1 and microRNA34a/Sirt1 signaling.

Reducing the Kidney Uptake of High Contrast CXCR4 PET Imaging Agents via Linker Modifications

Purpose: The C-X-C chemokine receptor 4 (CXCR4) is highly expressed in many subtypes of cancers, notably in several kidney-based malignancies. We synthesized, labeled, and assessed a series of radiotracers based on a previous high contrast PET imaging radiopharmaceutical [68Ga]Ga-BL02, with modifications to its linker and metal chelator, in order to improve its tumor-to-kidney contrast ratio. Methods: Based on the design of BL02, a piperidine-based cationic linker (BL06) and several anionic linkers (tri-Aad (BL17); tri-D-Glu (BL20); tri-Asp (BL25); and tri-cysteic acid (BL31)) were substituted for the triglutamate linker. Additionally, the DOTA chelator was swapped for a DOTAGA chelator (BL30). Each radiotracer was labeled with 68Ga and evaluated in CXCR4-expressing Daudi xenograft mice with biodistribution and/or PET imaging studies. Results: Of all the evaluated radiotracers, [68Ga]Ga-BL31 showed the most promising biodistribution profile, with a lower kidney uptake compared to [68Ga]Ga-BL02, while retaining the high imaging contrast capabilities of [68Ga]Ga-BL02. [68Ga]Ga-BL31 also compared favorably to [68Ga]Ga-Pentixafor, with superior imaging contrast in all non-target organs. The other anionic linker-based radiotracers showed either equivocal or worse contrast ratios compared to [68Ga]Ga-BL02; however, [68Ga]Ga-BL25 also showed lower kidney uptake, as compared to that of [68Ga]Ga-BL02. Meanwhile, [68Ga]Ga-BL06 had high non-target organ uptake and relatively lower tumor uptake, while [68Ga]Ga-BL30 showed significantly increased kidney uptake and similar tumor uptake values. Conclusions: [68Ga]Ga-BL31 is an optimized CXCR4-targeting radiopharmaceutical with lower kidney retention that has clinical potential for PET imaging and radioligand therapy.

Drug toxicity in the proximal tubule: new models, methods and mechanisms

The proximal tubule (PT) reabsorbs most of the glomerular filtrate and plays an important role in the uptake, metabolism and excretion of xenobiotics. Some therapeutic drugs are harmful to the PT, and resulting nephrotoxicity is thought to be responsible for approximately 1 in 6 of cases of children hospitalized with acute kidney injury (AKI). Clinically, PT dysfunction leads to urinary wasting of important solutes normally reabsorbed by this nephron segment, leading to systemic complications such as bone demineralization and a clinical scenario known as the renal Fanconi syndrome (RFS). While PT defects can be diagnosed using a combination of blood and urine markers, including urinary excretion of low molecular weight proteins (LMWP), standardized definitions of what constitutes clinically significant toxicity are lacking, and identifying which patients will go on to develop progressive loss of kidney function remains a major challenge. In addition, much of our understanding of cellular mechanisms of drug toxicity is still limited, partly due to the constraints of available cell and animal models. However, advances in new and more sophisticated in vitro models of the PT, along with the application of high-content analytical methods that can provide readouts more relevant to the clinical manifestations of nephrotoxicity, are beginning to extend our knowledge. Such technical progress should help in discovering new biomarkers that can better detect nephrotoxicity earlier and predict its long-term consequences, and herald a new era of more personalized medicine.

Role of rivaroxaban in sunitinib-induced renal injuries via inhibition of oxidative stress-induced apoptosis and inflammation through the tissue nacrosis factor-α induced nuclear factor-κappa B signaling pathway in rats

Rivaroxaban (RIVA) inhibits factor Xa and exhibits antithrombotic and anti-inflammatory activities by inhibiting several cellular signaling molecules. Sunitinib (SUN) is FDA approved first-line drug for metastatic renal cancers and advanced cancerous states of gastrointestinal tract. Present hypothesis was aimed to examine the nephroprotective potential of RIVA in SUN-induced nephrotoxicity, mediated through the inhibition of oxidative stress-induced apoptosis and inflammation, via the TNF-α/NFk-B signaling pathways. Wistar rats 200-250 g were selected and divided randomely in 5 groups (n = 6): Group 1 kept as normal control; Group 2 as disease control and exposed to SUN 50 mg/kg thrice-weekly upto 21 days; Groups 3 and 4, were treatment groups and administered SUN 50 mg/kg thrice-weekly as of group 2 and treated with RIVA 5 and 10 mg/kg/daily for 21 days, respectively; and Group 5 fed with RIVA alone (10 mg/kg/daily for 21 days). Serum was separated from blood to estimate serum biochemical parameters and kidney tissues were collected to estimate antioxidant enzyme, mRNA and protein expression. SUN exposure significantly elevated levels of creatinine, urea, uric acid, blood urea nitrogen, albumin, and bilirubin, and decreased serum magnesium and iron levels. Malondialdehyde and catalase levels were significantly increased and glutathione and glutathione reductase levels were significantly decreased. Intracellular levels of caspase-3 and TNF-α were significantly increased; RIVA treatment restored the altered levels. In SUN-exposed animals, western blotting revealed significantly elevated NFk-B, IL-17, and MCP-1 expression, and IKBα levels were significantly downregulated; RIVA restored these levels to normal values.RIVA treatment significantly restored the apoptotic and inflammatory parameters in SUN-damaged renal tissues.

Rebamipide potentially mitigates methotrexate-induced nephrotoxicity via inhibition of oxidative stress and inflammation: A molecular and histochemical study

Methotrexate (MTX) is a widely used chemotherapeutic agent; nevertheless, the nephrotoxicity associated with its use has limited its clinical use. Rebamipide (REB) is a gastro-protective agent with diverse promising biological activities. Here, we investigated the renoprotective effects of REB against MTX-induced nephrotoxicity in rats. Male Wistar rats were allocated into four groups: the normal control group, the REB group (100 mg kg^-1 day^-1 , PO, for 12 days), the MTX group (which received a single injection of 20 mg/kg, ip), and the REB + MTX group (which received 100 mg kg^-1 day^-1 REB for 7 days before and 5 days after being injected with 20 mg/kg MTX). Interestingly, MTX triggered kidney injury, characterized by renal dysfunction along with histopathological alterations. Moreover, increased reactive oxygen species level and inflammatory response were detected in the kidney of MTX-treated rats. However, REB prevented MTX-induced oxidative kidney injury and boosted an antioxidant balance. Mechanistically, REB markedly activated the NRF-2 protein and upregulated the expression of both SIRT-1 and FOXO-3 genes. Additionally, REB administration strongly inhibited the inflammatory response by downregulating both NF-κB-p65 and TLR-4. Finally, the coadministration of REB and MTX activated the mTOR/PI3K/AKT signaling pathway. Simultaneously, REB treatment attenuated the reduction in glomerular size, the widening of the capsular spaces, and the tubular cell damage due to MTX administration. Taken together, these results indicate the potential of REB as adjuvant therapy to prevent nephrotoxicity in patients receiving MTX treatment.

Nephroprotective Effect of Cilastatin against Gentamicin-Induced Renal Injury In Vitro and In Vivo without Altering Its Bactericidal Efficiency

Gentamicin is a used antibiotic that causes nephrotoxicity in 10-20% of treatment periods, which limits its use considerably. Our results have shown that cilastatin may be a promising therapeutic alternative in toxin-induced acute kidney injury (AKI). Here, we investigated its potential use as a nephroprotector against gentamicin-induced AKI in vitro and in vivo. Porcine renal cells and rats were treated with gentamicin and/or cilastatin. In vivo nephrotoxicity was analyzed by measuring biochemical markers and renal morphology. Different apoptotic, oxidative and inflammatory parameters were studied at cellular and systemic levels. Megalin, mainly responsible for the entry of gentamicin into the cells, was also analyzed. Results show that cilastatin protects cells from gentamicin-induced AKI. Cilastatin decreased creatinine, BUN, kidney injury molecule-1 (KIM-1) and severe morphological changes previously increased by gentamicin in rats. The interference of cilastatin with lipid rafts cycling leads to decreased expression of megalin, and therefore gentamicin uptake and myeloid bodies, resulting in a decrease of apoptotic, oxidative and inflammatory events. Moreover, cilastatin did not prevent bacterial death by gentamicin. Cilastatin reduced gentamicin-induced AKI by preventing key steps in the amplification of the damage, which is associated to the disruption of megalin-gentamicin endocytosis. Therefore, cilastatin might represent a novel therapeutic tool in the prevention and treatment of gentamicin-induced AKI in the clinical setting.

Sinapic acid attenuates cisplatin-induced nephrotoxicity through peroxisome proliferator-activated receptor gamma agonism in rats

AIM

The aim of this study was to investigate the involvement of peroxisome proliferator-activated receptor gamma (PPAR-γ) in renal protection offered by sinapic acid in cisplatin-induced nephrotoxicity in male rats.

MATERIALS AND METHODS

Nephrotoxicity was induced by single dose of cisplatin (5 mg/kg, intraperitoneal [i.p.]) in rats. Cisplatin-induced nephrotoxicity was assessed by measuring serum creatinine, creatinine clearance, urea, uric acid, potassium, magnesium levels, fractional excretion of sodium, and microproteinuria in rats. Superoxide anion generation, thiobarbituric acid reactive substances, myeloperoxidase activity, and reduced glutathione levels were measured to assess oxidative stress in renal tissues. Hematoxylin and eosin stain showed renal histological changes.

RESULTS

The significant changes in serum and urinary parameters, elevated oxidative stress, and renal histological changes established the induction of nephrotoxicity. Sinapic acid treatment (20 and 40 mg/kg, orally [p.o.]) provides dose-dependent and significant (P < 0.05) nephroprotection against cisplatin-mediated nephrotoxicity in rats. Nephroprotective effect of sinapic acid was abolished by PPAR-γ inhibitor, bisphenol A diglycidyl ether (30 mg/kg, i.p.) in rats.

CONCLUSION

It is concluded that PPAR-γ agonism serves as one of the mechanisms in sinapic acid-mediated renoprotection.

The Predictive Role of the Biomarker Kidney Molecule-1 (KIM-1) in Acute Kidney Injury (AKI) Cisplatin-Induced Nephrotoxicity

Acute kidney injury (AKI) following platinum-based chemotherapeutics is a frequently reported serious side-effect. However, there are no approved biomarkers that can properly identify proximal tubular injury while routine assessments such as serum creatinine lack sensitivity. Kidney-injury-molecule 1 (KIM-1) is showing promise in identifying cisplatin-induced renal injury both in vitro and in vivo studies. In this review, we focus on describing the mechanisms of renal tubular cells cisplatin-induced apoptosis, the associated inflammatory response and oxidative stress and the role of KIM-1 as a possible biomarker used to predict cisplatin associated AKI.

Early investigational drugs for hearing loss

INTRODUCTION

Sensorineural hearing loss (HL) is becoming a global phenomenon at an alarming rate. Nearly 600 million people have been estimated to have significant HL in at least one ear. There are several different causes of sensorineural HL included in this review of new investigational drugs for HL. They are noise-induced, drug-induced, sudden sensorineural HL, presbycusis and HL due to cytomegalovirus infections.

AREAS COVERED

This review presents trends in research for new investigational drugs encompassing a variety of causes of HL. The studies presented here are the latest developments either in the research laboratories or in preclinical, Phase 0, Phase I or Phase II clinical trials for drugs targeting HL.

EXPERT OPINION

While it is important that prophylactic measures are developed, it is extremely crucial that rescue strategies for unexpected or unavoidable cochlear insult be established. To achieve this goal for the development of drugs for HL, innovative strategies and extensive testing are required for progress from the bench to bedside. However, although a great deal of research needs to be done to achieve the ultimate goal of protecting the ear against acquired sensorineural HL, we are likely to see exciting breakthroughs in the near future.

Drug-induced nephrotoxicity and its biomarkers

Nephrotoxicity occurs when kidney-specific detoxification and excretion do not work properly due to the damage or destruction of kidney function by exogenous or endogenous toxicants. Exposure to drugs often results in toxicity in kidney which represents the major control system maintaining homeostasis of body and thus is especially susceptible to xenobiotics. Understanding the toxic mechanisms for nephrotoxicity provides useful information on the development of drugs with therapeutic benefi ts with reduced side effects. Mechanisms for drug-induced nephrotoxicity include changes in glomerular hemodynamics, tubular cell toxicity, inflammation, crystal nephropathy, rhabdomyolysis, and thrombotic microangiopathy. Biomarkers have been identifi ed for the assessment of nephrotoxicity. The discovery and development of novel biomarkers that can diagnose kidney damage earlier and more accurately are needed for effective prevention of drug-induced nephrotoxicity. Although some of them fail to confer specificity and sensitivity, several promising candidates of biomarkers were recently proved for assessment of nephrotoxicity. In this review, we summarize mechanisms of drug-induced nephrotoxicity and present the list of drugs that cause nephrotoxicity and biomarkers that can be used for early assessment of nephrotoxicity.

Megalin in acute kidney injury: foe and friend

The kidney proximal tubule is a key target in many forms of acute kidney injury (AKI). The multiligand receptor megalin is responsible for the normal proximal tubule uptake of filtered molecules, including nephrotoxins, cytokines, and markers of AKI. By mediating the uptake of nephrotoxins, megalin plays an essential role in the development of some types of AKI. However, megalin also mediates the tubular uptake of molecules implicated in the protection against AKI, and changes in megalin expression have been demonstrated in AKI in animal models. Thus, modulation of megalin expression in response to AKI may be an important part of the tubule cell adaption to cellular protection and regeneration and should be further investigated as a potential target of intervention. This review explores current evidence linking megalin expression and function to the development, diagnosis, and progression of AKI as well as renal protection against AKI.

Influence of aminoglycoside antibiotics on chicken cystatin binding to renal brush-border membranes

Objectives

Drug-induced kidney injury is a serious adverse event which needs to be monitored during aminoglycoside therapy. Urine cystatin C is considered an early and sensitive marker of nephrotoxicity. Cystatin C, a low-molecular-weight serum protein, and basic drugs have a common transport system expressed in the apical membrane of renal proximal tubular cells. The aim of this study was to investigate whether aminoglycoside antibiotics influenced cystatin C binding to the renal brush-border membrane.

Methods

The binding study was performed using a rapid filtration technique and affinity column displacement method.

Key findings

Concentration-dependent inhibition of chicken cystatin binding to brush-border membranes by gentamicin was observed. The gentamicin interaction with brush-border membranes was of relatively low affinity (Ki = 32 μm) in comparison with the chicken cystatin affinity to the binding sites (Kd = 3.6 μm). Amikacin and gentamicin were only able to displace chicken cystatin from the chromatographic affinity column in concentrations several times higher than normally found in the tubular fluid during standard aminoglycoside therapy.

Conclusion

Cystatin reabsorption in the proximal tubule cannot be significantly affected by aminoglycoside antibiotics because of their relatively low affinity to common binding sites on the brush-border membrane.

Effect of protamine on the accumulation of gentamicin in opossum kidney epithelial cells

Objectives

The purpose of this study was to examine whether or not protamine, an arginine-rich basic protein mixture, inhibits the accumulation of gentamicin, a nephrotoxic drug, in cultured opossum kidney (OK) epithelial cells.

Methods

The effect of protamine from salmon on accumulation and binding of [3H]gentamicin was investigated in OK cells.

Key findings

Protamine inhibited the binding and accumulation of [3H]gentamicin in a concentration-dependent manner. The accumulation of [14C]inulin, a marker of fluid-phase endocytosis, was not affected by protamine at concentrations up to 1 mm. l-Arginine at concentrations up to 10 mm had no significant effect on the accumulation of [3H]gentamicin. On the other hand, preincubation with 100 μm protamine for 5 min decreased the accumulation of [3H]gentamicin to almost the same extent as coincubation with 100 μm protamine for 60 min.

Conclusions

Our results indicate that protamine decreases the accumulation of gentamicin in OK cells. These findings suggest that protamine or its derivatives might be useful in preventing the nephrotoxicity of aminoglycoside antibiotics including gentamicin.

Cryptic parasite revealed improved prospects for treatment and control of human cryptosporidiosis through advanced technologies

Cryptosporidium is an important genus of parasitic protozoa of humans and other vertebrates and is a major cause of intestinal disease globally. Unlike many common causes of infectious enteritis, there are no widely available, effective vaccine or drug-based intervention strategies for Cryptosporidium, and control is focused mainly on prevention. This approach is particularly deficient for infections of severely immunocompromised and/or suppressed, the elderly or malnourished people. However, cryptosporidiosis also presents a significant burden on immunocompetent individuals, and can, for example have lasting effects on the physical and mental development of children infected at an early age. In the last few decades, our understanding of Cryptosporidium has expanded significantly in numerous areas, including the parasite life-cycle, the processes of excystation, cellular invasion and reproduction, and the interplay between parasite and host. Nonetheless, despite extensive research, many aspects of the biology of Cryptosporidium remain unknown, and treatment and control are challenging. Here, we review the current state of knowledge of Cryptosporidium, with a focus on major advances arising from the recently completed genome sequences of the two species of greatest relevance in humans, namely Cryptosporidium hominis and Cryptosporidium parvum. In addition, we discuss the potential of next-generation sequencing technologies, new advances in in silico analyses and progress in in vitro culturing systems to bridge these gaps and to lead toward effective treatment and control of cryptosporidiosis.