The preventive and therapeutic effects of α-lipoic acid on ethylene glycol-induced calcium oxalate deposition in rats

Antistress and Antiaging Potentials of Alpha-Lipoic Acid: Insights from Cell Culture-Based Experiments

Chronic stress has been linked to a large number of pathologies, including cancer, premature aging, and neurodegenerative diseases. The accumulation of molecular waste resulting from oxidative and heavy metal-induced stress has been ascribed as a major factor contributing to these diseases. With this in mind, we started by screening 13 small molecules to determine their antistress potential in heavy metal stress-exposed C6 glioblastoma and found that alpha-lipoic acid (ALA) (a natural antioxidant abundantly present in yeast, spinach, broccoli, and meat) was the most effective candidate. We then conducted molecular analyses to validate its mechanism of action. Dose-dependent toxicity assays of cells treated with two ALA enantiomers, R-ALA and S-ALA, showed that they are nontoxic and can be tolerated at relatively high doses. Cells exposed to heavy metal, heat, and oxidative stress showed better recovery when cultured in R-ALA-/S-ALA-supplemented medium, supported by reduction of reactive oxygen species (ROS), aggregated proteins, and mitochondrial and deoxyribonucleic acid (DNA) damage. Molecular analyses revealed protection against stress-induced apoptosis and induction of autophagy in R-ALA- and S-ALA-treated C6/U2OS cells. Consistent with these findings, normal human fibroblasts showed lifespan extension. Taken together, this study demonstrates that lipoic acid has antiaging and antistress potential and warrants further attention in laboratory and clinical studies.

Myricetin Attenuates Ethylene Glycol-Induced Nephrolithiasis in Rats via Mitigating Oxidative Stress and Inflammatory Markers

Urolithiasis or nephrolithiasis is a condition of kidney stone formation and is considered a painful disease of the urinary tract system. In this work, we planned to discover the therapeutic roles of myricetin on the ethylene glycol (EG)-induced nephrolithiasis in rats. The experimental rats were treated with 0.75% of EG through drinking water for 4 weeks to initiate the nephrolithiasis and subsequently treated with 25 and 50 mg/kg of myricetin. The body weight and urine volume were measured regularly. After the sacrification of rats, the samples were collected, and serum and urinary biomarkers such as creatinine, urea, Ca2 + ion, and BUN, OPN, oxalate, and citrate levels were determined using assay kits. These biomarkers, the MDA level and CAT, SOD, and GPx activities, were assessed in the kidney tissue homogenates. The IL-6, IL-1β, and TNF-α levels were also quantified using respective kits. The histopathological analysis was done on the kidney tissues. Myricetin treatment did not show major changes in the body weight and kidney weight in the EG-induced rats. The treatment with 25 and 50 mg/kg of myricetin considerably reduced the urea, creatinine, BUN, Ca2 + ion, and oxalate and increased the citrate content in serum and urine samples of EG-induced rats. Further, myricetin depleted the inflammatory cytokines and MDA levels and elevated the CAT, SOD, and GPx activities in the renal tissues. The activities of ALT, AST, ALP, GGT, and LDH were also reduced by the myricetin. Furthermore, the myricetin upheld the histoarchitecture of the kidneys. The outcomes of this investigation propose that myricetin is effective in EG-induced urolithiasis probably because of its antioxidant, anti-inflammatory, and renoprotective activities. In addition, further studies are still required to verify the precise therapeutic mechanism of myricetin.

Oxidized forms of uromodulin promote calcium oxalate crystallization and growth, but not aggregation

Roles of an abundant human urinary protein, uromodulin (UMOD), in kidney stone disease were previously controversial. Recently, we have demonstrated that oxidative modification reverses overall modulatory activity of whole urinary proteins, from inhibition to promotion of calcium oxalate (CaOx) stone-forming processes. We thus hypothesized that oxidation is one of the factors causing those previously controversial UMOD data on stone modulation. Herein, we addressed effects of performic-induced oxidation on CaOx crystal modulatory activity of UMOD. Sequence analyses revealed two EGF-like calcium-binding domains (65th-107th and 108th-149th), two other calcium-binding motifs (65th-92nd and 108th-135th), and three oxalate-binding motifs (199th-207th, 361st-368th and 601st-609th) in UMOD molecule. Analysis of tandem mass spectrometric dataset of whole urinary proteins confirmed marked increases in oxidation, dioxidation and trioxidation of UMOD in the performic-modified urine samples. UMOD was then purified from the normal urine and underwent performic-induced oxidative modification, which was confirmed by Oxyblotting. The oxidized UMOD significantly promoted CaOx crystallization and crystal growth, whereas the unmodified native UMOD inhibited CaOx crystal growth. However, the oxidized UMOD did not affect CaOx crystal aggregation. Therefore, our data indicate that oxidized forms of UMOD promote CaOx crystallization and crystal growth, which are the important processes for CaOx kidney stone formation.

Ample dietary fat reduced the risk of primary vesical calculi by inducing macrophages to engulf budding crystals in mice

Although primary vesical calculi is an ancient disease, the mechanism of calculi formation remains unclear. In this study, we established a novel primary vesical calculi model with d,l-choline tartrate in mice. Compared with commonly used melamine and ethylene glycol models, our model was the only approach that induced vesical calculi without causing kidney injury. Previous studies suggest that proteins in the daily diet are the main contributors to the prevention of vesical calculi, yet the effect of fat is overlooked. To assay the relationship of dietary fat with the formation of primary vesical calculi, d,l-choline tartrate-treated mice were fed a high-fat, low-fat, or normal-fat diet. Genetic changes in the mouse bladder were detected with transcriptome analysis. A high-fat diet remarkably reduced the morbidity of primary vesical calculi. Higher fatty acid levels in serum and urine were observed in the high-fat diet group, and more intact epithelia in bladder were observed in the same group compared with the normal- and low-fat diet groups, suggesting the protective effect of fatty acids on bladder epithelia to maintain its normal histological structure. Transcriptome analysis revealed that the macrophage differentiation-related gene C–X–C motif chemokine ligand 14 (Cxcl14) was upregulated in the bladders of high-fat diet-fed mice compared with those of normal- or low-fat diet-fed mice, which was consistent with histological observations. The expression of CXCL14 significantly increased in the bladder in the high-fat diet group. CXCL14 enhanced the recruitment of macrophages to the crystal nucleus and induced the transformation of M2 macrophages, which led to phagocytosis of budding crystals and prevented accumulation of calculi. In human bladder epithelia (HCV-29) cells, high fatty acid supplementation significantly increased the expression of CXCL14. Dietary fat is essential for the maintenance of physiological functions of the bladder and for the prevention of primary vesical calculi, which provides new ideas for the reduction of morbidity of primary vesical calculi.

Hydroxycitrate prevents calcium oxalate crystallization and kidney injury in a nephrolithiasis rat model

Hydroxycitrate (HCA) is a derivative of citric acid, and previous studies of HCA have revealed its ability to inhibit the formation of calcium oxalate crystals in vitro. To date, there has been little evidence proving that HCA has the same effectiveness in vivo. The present study was designed to investigate the ameliorating effect of HCA on calcium oxalate deposition and renal impairment in a male rat model. Male Sprague-Dawley rats were randomly divided into four groups: a control group, a model group (glyoxalic acid), a CA group (glyoxalic acid + CA), and an HCA group (glyoxalic acid + HCA). Kidney stone formation was induced by injection of glyoxalic acid (60 mg/kg). The results showed that serum and urinary parameters were significantly improved by HCA treatment. In addition, differences in the formation of calcium oxalate crystals between groups were observed, and HCA was superior to CA in inhibiting crystal accumulation. The ultrastructure of renal tubules and glomeruli occurred in the model group, and the above lesions were significantly reduced in the HCA group. Both OPN and SOD expression levels were promoted by HCA, while CA only promoted OPN. In this article, we provided data on whether HCA affected kidney stones and the expression levels of OPN and SOD in a male rat model.

Outcomes of dissolution therapy and monitoring for stone disease: should we do better?

PURPOSE OF REVIEW

Surgical management is the cornerstone of urolithiasis treatment, but high recurrence rates and associated complications necessitate the existence of medical treatment options, aiming at dissolution of kidney stones and prevention of recurrence. The purpose of this review is to present the most recent knowledge existing in scientific literature, regarding dissolution therapy and ways of monitoring nephrolithiasis patients.

RECENT FINDINGS

A number of laboratory studies have been performed testing experimental treatments (tolvaptan, chlorthalidone, atorvastatin, a-lipoic acid, glucosaminoglycans, plant extracts), to reduce kidney stone formation and cellular damage and showed encouraging results. Uric acid stones is the main target of dissolution therapy, but until last years, existing level of evidence was low. A number of prospective and randomized studies, proved the efficacy and safety of oral chemolysis for radiolucent stones and associated prognostic features of success. Tolvaptan and a-Lipoic acid were also tested in patients with cystinuria and resulted in reduction of recurrence. Finally, some new diagnostic markers are suggested as tests for the monitoring of urolithiasis patients, with satisfying accuracy and discriminative ability.

SUMMARY

Medical dissolution therapy for nephrolithiasis is an effective option, especially for patients with radiolucent/uric acid stones. In the future, we need clinical trials to confirm the encouraging results of pilot studies testing several agents for patients with cystinuria.