The effect of aryl hydrocarbon receptor ligands on gentamicin-induced nephrotoxicity in rats

An in silico study on human carcinogenicity mechanism of polybrominated biphenyls exposure

Polybrominated biphenyls (PBBs) are associated with an increased risk of thyroid cancer; however, relevant mechanistic studies are lacking. In this study, we investigated the mechanisms underlying PBB-induced human thyroid cancer. Molecular docking and molecular dynamics methods were employed to investigate the metabolism of PBBs by the cytochrome P450 enzyme under aryl hydrocarbon receptor mediation into mono- and di-hydroxylated metabolites. This was taken as the molecular initiation event. Subsequently, considering the interactions of PBBs and their metabolites with the thyroxine-binding globulin protein as key events, an adverse outcome pathway for thyroid cancer caused by PBBs exposure was constructed. Based on 2D quantitative structure activity relationship (2D-QSAR) models, the contribution of amino acid residues and binding energy were analyzed to understand the mechanism underlying human carcinogenicity (adverse effect) of PBBs. Hydrogen bond and van der Waals interactions were identified as key factors influencing the carcinogenic adverse outcome pathway of PBBs. Analysis of non-bonding forces revealed that PBBs and their hydroxylation products were predominantly bound to the thyroxine-binding globulin protein through hydrophobic and hydrogen bond interactions. The key amino acids involved in hydrophobic interactions were alanine 330, arginine 381 and lysine 270, and the key amino acids involved in hydrogen bond interactions were arginine 381 and lysine 270. This study provides valuable insights into the mechanisms underlying human health risk associated with PBBs exposure.

Megalin, a multi-ligand endocytic receptor, and its participation in renal function and diseases: A review

The endocytosis mechanism is a complicated system that is essential for cell signaling and survival. Megalin, a membrane-associated endocytic receptor, and its related proteins such as cubilin, the neonatal Fc receptor for IgG, and NaPi-IIa are important in receptors-mediated endocytosis. Physiologically, megalin uptakes plasma vitamins and proteins from primary urine, preventing their loss. It also facilitates tubular retrieval of solutes and endogenous components that may be involved in modulation and recovery from kidney injuries. Moreover, megalin is responsible for endocytosis of xenobiotics and drugs in renal tubules, increasing their half-life and/or their toxicity. Fluctuations in megalin expression and/or functionality due to changes in its regulatory mechanisms are associated with some sort of kidney injury. Also, it's an important component of several pathological conditions, including diabetic nephropathy and Dent disease. Thus, exploring the fundamental role of megalin in the kidney might help in the protection and/or treatment of multiple kidney-related diseases. Hence, this review aimed to explore the physiological roles of megalin in the kidney and their implications for kidney-related injuries.

Pharmacological blockage of the AHR-CYP1A1 axis: a call for in vivo evidence

The aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor that can be activated by structurally diverse compounds arising from the environment and the microbiota and host metabolism. Expanding evidence has been shown that the modulation of the canonical pathway of AHR occurs during several chronic diseases and that its abrogation might be of clinical interest for metabolic and inflammatory pathological processes. However, most of the evidence on the pharmacological abrogation of the AHR-CYP1A1 axis has been reported in vitro, and therefore, guidance for in vivo studies is needed. In this review, we cover the state-of-the-art of the pharmacodynamic and pharmacokinetic properties of AHR antagonists and CYP1A1 inhibitors in different in vivo rodent (mouse or rat) models of disease. This review will serve as a road map for those researchers embracing this emerging therapeutic area targeting the AHR. Moreover, it is a timely opportunity as the first AHR antagonists have recently entered the clinical stage of drug development.

Lycopene Preventing DEHP-Induced Renal Cell Damage Is Targeted by Aryl Hydrocarbon Receptor

Di (2-ethylhexyl) phthalate (DEHP) is an environmentally persistent and bioaccumulative plasticizer. Accumulation of DEHP in the body can eventually cause kidney damage. As a type of natural carotenoid, lycopene (LYC) has a potential protective effect on renal cells, but the protective mechanism has not yet been elucidated. The major goal of this study was to see how effective LYC was at treating DEHP-induced nephrotoxicity in mice. ICR mice were treated with DEHP (500 mg/kg BW/day or 1000 mg/kg BW/day) or LYC (5 mg/kg BW/day) for 28 days. Through histopathology and ultrastructure, we found that LYC attenuated DEHP-induced renal tubular cell and glomerular damage. LYC relieved DEHP-induced kidney injury evidenced by lower levels of blood urea nitrogen (Bun), creatinine (Cre), and uric acid (Uric). Meanwhile, the reduced expression of kidney injury molecule-1 (Kim-1) also supported it. Notably, LYC can alleviate the activity or content of cytochrome P450 system (CYP450s) interfered with by DEHP. In addition, LYC treatment reduced nuclear accumulation of DEHP-induced aromatic hydrocarbon receptor (AhR) and AhR nuclear transporter (Arnt), and its downstream target genes such as cytochrome P450-dependent monooxygenase (CYP) 1A1, 1A2, and 1B1 expression significantly decreased to normal in the LYC treatment group. In summary, LYC can mediate the AhR/Arnt signaling system to prevent kidney toxicity in mice caused by DEHP exposure.

Adverse Impact of Environmental Chemicals on Developmental Origins of Kidney Disease and Hypertension

Chronic kidney disease (CKD) and hypertension are becoming a global health challenge, despite developments in pharmacotherapy. Both diseases can begin in early life by so-called "developmental origins of health and disease" (DOHaD). Environmental chemical exposure during pregnancy can affect kidney development, resulting in renal programming. Here, we focus on environmental chemicals that pregnant mothers are likely to be exposed, including dioxins, bisphenol A (BPA), phthalates, per- and polyfluoroalkyl substances (PFAS), polycyclic aromatic hydrocarbons (PAH), heavy metals, and air pollution. We summarize current human evidence and animal models that supports the link between prenatal exposure to environmental chemicals and developmental origins of kidney disease and hypertension, with an emphasis on common mechanisms. These include oxidative stress, renin-angiotensin system, reduced nephron numbers, and aryl hydrocarbon receptor signaling pathway. Urgent action is required to identify toxic chemicals in the environment, avoid harmful chemicals exposure during pregnancy and lactation, and continue to discover other potentially harmful chemicals. Innovation is also needed to identify kidney disease and hypertension in the earliest stage, as well as translating effective reprogramming interventions from animal studies into clinical practice. Toward DOHaD approach, prohibiting toxic chemical exposure and better understanding of underlying mechanisms, we have the potential to reduce global burden of kidney disease and hypertension.

MicroRNA-567 inhibits cell proliferation and induces cell apoptosis in A549 NSCLC cells by regulating cyclin-dependent kinase 8

MicroRNA-567 (miR-567) plays a decisive role in cancers whereas its role in non-small cell lung cancer (NSCLC) is still unexplored. This study was therefore planned to explore the regulatory function of miR-567 in A549 NSCLC cells and investigate its possible molecular mechanism that may help in NSCLC treatment. In the current study, miR-567 expression was examined by quantitative real time-polymerase chain reaction (qRT-PCR) in different NSCLC cell lines in addition to normal cell line. A549 NSCLC cells were transfected by miR-567 mimic, miR-567 inhibitor, and negative control siRNA. Cell proliferation was evaluated by MTT and 5-bromo-2'deoxyuridine assays. Cell cycle distribution and apoptosis were studied by flow cytometry. Bioinformatics analysis programs were used to expect the putative target of miR-567. The expression of cyclin-dependent kinase 8 (CDK8) gene at mRNA and protein levels were evaluated by using qRT-PCR and western blotting. Our results found that miR-567 expressions decreased in all the studied NSCLC cells as compared to the normal cell line. A549 cell proliferation was suppressed by miR-567 upregulation while cell apoptosis was promoted. Also, miR-567 upregulation induced cell cycle arrest at sub-G1 and S phases. CDK8 was expected as a target gene of miR-567. MiR-567 upregulation decreased CDK8 mRNA and protein expression while the downregulation of miR-567 increased CDK8 gene expression. These findings revealed that miR-567 may be a tumor suppressor in A549 NSCLC cells through regulating CDK8 gene expression and may serve as a novel therapeutic target for NSCLC treatment.

Royal Jelly and Aliskiren mutually annul their protective effects against gentamicin-induced nephrotoxicity in rats

Background and Aim

Gentamicin (GM) is one of the most effective antibiotics for severe, life-threatening Gram-negative infections. Nevertheless, its clinical use has been restrained because of its nephrotoxic potential. Royal jelly (RJ) and aliskiren (ALK) can individually prevent such toxic effects. The aim of this study was to explore the protective effects of a combination treatment of RJ and ALK on GM-mediated nephrotoxicity.

Materials and Methods

Thirty-two adult female. Wistar rats were divided equally into four groups: (I) Receiving normal saline; (II) GM (100 mg/kg, intraperitoneal [i.p.] injection); GM (100 mg/kg, i.p. injection) plus ALK (50 mg/kg, i.p. injection); and (IV) GM (100 mg/kg, i.p. injection) plus ALK (50 mg/kg, i.p. injection) in combination with RJ (150 mg/kg, orally). All treatments were administered daily for 10 days. The blood levels of creatinine, urea, uric acid, albumin, and total protein were measured. Then, the animals were sacrificed, and the kidneys were taken for histopathology.

Results

Compared to normal control rats, GM-injected rats showed significantly (p<0.001) higher serum concentrations of uric acid, urea, and creatinine as well as evidently (p<0.001) lower blood levels of albumin and total protein. Moreover, GM administration was associated with significant renal histopathological changes. All these alterations were considerably (p<0.05) improved in GM-injected rats receiving ALK compared to rats receiving GM alone. However, when RJ was given in combination with ALK to GM-injected rats, it lessened the beneficial nephroprotective effects of both agents.

Conclusion

The combination treatment of RJ and ALK is not desirable for GM-induced nephrotoxicity. Further studies are crucial to accurately explore the precise mechanism of RJ antagonistic interaction with ALK.

Androgen/androgen receptor affects gentamicin-induced nephrotoxicity through regulation of megalin expression

AIM

Investigation whether androgen/androgen receptor (AR) might regulate megalin expression and/or functionality and thus affecting Gentamicin-induced nephrotoxicity (GIN).

MAIN METHODS

Male Wistar rats were treated with gentamicin with/out AR ligands (testosterone as agonist and flutamide as antagonist). Megalin expression in the kidney tissues was determined by real-time RT-PCR and western blot. Besides, megalin functionality was assessed using immunofluorescence imaging of fluorescein isothiocyanate (FITC) conjugated bovine serum albumin (BSA) (FITC-BSA). The effects of different treatments on the kidney were assessed at the structural level by histopathological evaluation and the biochemical level by colorimetric assay of blood urea nitrogen (BUN), serum creatinine (SCr) and urinary albumin/creatinine (A/C) ratio, besides, kidney expression of neutrophil gelatinase-associated lipocalin (NGAL) by immunoblotting.

KEY FINDINGS

Our results revealed that treatment with testosterone either alone or combined with gentamicin increased megalin expression at mRNA and protein levels as well as at the functional level. These effects were paralleled by increased GIN as manifested by increased SCr, BUN, A/C ratio, renal expression of NGAL or histopathological changes. On the other hand, treatment with flutamide ameliorated GIN and megalin expression and functionality. Computational analysis of megalin promotor revealed the presence of multiple response elements that mediate androgen response.

SIGNIFICANCE

Androgen/AR regulates megalin expression at the transcriptional level and consequently GIN. This may explain the sexual dimorphism in GIN and might represent a druggable target for treatment or prevention of GIN.