Animal models of kidney stone formation: an analysis

Plant-based therapies for urolithiasis: a systematic review of clinical and preclinical studies

PURPOSE

Urolithiasis, the formation of kidney stones, is a common and severe condition. Despite advances in understanding its pathophysiology, affordable treatment options are needed worldwide. Hence, the interest is in herbal medicines as alternative or supplementary therapy for urinary stone disease. This review explores the use of plant extracts and phytochemicals in preventing and treating urolithiasis.

METHODS

Following PRISMA standards, we systematically reviewed the literature on PubMed/Medline, focusing on herbal items evaluated in in vivo models, in vitro studies, and clinical trials related to nephrolithiasis/urolithiasis. We searched English language publications from January 2021 to December 2023. Studies assessing plant extracts and phytochemicals' therapeutic potential in urolithiasis were included. Data extracted included study design, stone type, plant type, part of plant used, solvent type, main findings, and study references.

RESULTS

A total of 64 studies were included. Most studies used ethylene glycol to induce hyperoxaluria and nephrolithiasis in rat models. Various extraction methods were used to extract bioactive compounds from different plant parts. Several plants and phytochemicals, including Alhagi maurorum, Aerva lanata, Dolichos biflorus, Cucumis melo, and quercetin, demonstrated potential effectiveness in reducing stone formation, size, and number.

CONCLUSIONS

Natural substances offer an alternative or supplementary approach to current treatments, potentially reducing pain and improving the quality of life for urolithiasis patients. However, further research is needed to clarify their mechanisms of action and optimize their therapeutic use. The potential of plant-based therapies in treating urolithiasis is promising, and ongoing research is expected to lead to treatment advancements benefiting patients globally.

Antiurolithiatic effects of Cassia fistula Lin. fruit extracts on ethylene glycol-induced nephrolithiasis in rats

Urinary stones are a growing disease that results from pathological biomineralization. Cassia fistula Lin. is traditionally used to treat urinary stones. However, no scientific evidence is available to prove its antilithiatic effect. This study evaluates the antilithiatic potential of aqueous and ethanolic extract of Cassia fistula Lin. fruit (Cff) against calcium oxalate kidney stones. Forty-two male Wistar rats were divided into seven groups (n = 6/group): Group I (control), Group II (rats treated with ethylene glycol and ammonium chloride developed nephrolithiasis after 28 days), Group III (lithiatic rats receiving distilled water for 30 days), Group IV and V (lithiatic rats receiving aqueous extract of Cff at doses of 1 and 100 mg/kg body weight for 30 days, respectively) and Group VI and VII (lithiatic rats receiving ethanolic extract of Cff at doses of 1 and 100 mg/kg body weight for 30 days, respectively). Some parameters of urine and serum, and also renal oxidative stress and histopathology were used to determine the antilithiatic effect of aqueous and ethanolic extract of Cff. Therefore, the types of extracts of Cff improved abnormal levels of urine, serum, and renal oxidative stress and histopathology parameters. This antilithiatic effect of aqueous and ethanolic extracts of Cff, can be attributed to the anti-crystallization and antioxidant properties of the extracts and the ability to improve urine and serum biochemistry. RESEARCH HIGHLIGHTS: Ethylene glycol and ammonium chloride-induced urolithiasis, aggregation of calcium oxalate deposits, increase of some urinary and serum parameters, relative kidney weight, kidney size and MDA activity, decrease of some urinary parameters, relative body weight and SOD activity. Aqueous and ethanolic extracts of Cassia fistula Lin. lead to the treatment of urolithic rats by decreasing levels of urinary oxalate, phosphate, urea, serum urea, uric acid, creatinine, calcium, phosphate, MDA, kidney weight and kidney size, increasing levels of urinary calcium, creatinine, magnesium, citrate, body weight and SOD activity in the kidney, eliminating CaOx deposition (esp. ethanolic extract).

Protective Role of Rosmarinic Acid in Experimental Urolithiasis: Understanding Its Impact on Renal Parameters

This study aimed to assess the ability of rosmarinic acid (RA) to prevent kidney stone formation in an ethylene glycol and ammonium chloride (EG/AC) model. There was an increase in diuresis in the normotensive (NTRs) and hypertensive rats (SHRs) treated with hydrochlorothiazide (HCTZ) and exposed to EG/AC, while RA restored urine volume in NTRs. The EG/AC groups exhibited lower urine pH and electrolyte imbalance; these parameters were not affected by any of the treatments. Both HCTZ+EG/AC and RA+EG/AC reduced calcium oxalate crystal formation in NTR and SHR urine. Kidney tissue analysis revealed alterations in oxidative stress and inflammation parameters in all EG/AC-receiving groups, with RA enhancing antioxidant defenses in SHRs. Additionally, crystals were found in the kidney histology of all EG/AC-exposed groups, with reduced Bowman's capsule areas in NTRs and SHRs. The NTR VEH+EG/AC group showed intense renal damage, while the others maintained their structures, where treatments with HCTZ and RA were fundamental for kidney protection in the NTRs. Docking analysis showed that RA exhibited good binding affinity with matrix metalloproteinase-9, phosphoethanolamine cytidylyltransferase, and human glycolate oxidase enzymes. The data disclosed herein underscore the importance of further research to understand the underlying mechanisms better and validate the potential of RA for clinical use.

Ethanolic extract of cotinuscoggygria leaves attenuates crystalluria and kidney damage in ethylene glycol-induced urolithiasis in rats

OBJECTIVE

Nephrolithiasis is a common cause of kidney insufficiency. Nephrolithiasis is proven to be the result of various biochemical and inflammatory processes that result in crystal formation and subsequent aggregation. Cotinuscoggygria L. (CCog) is a plant extract which has been used as a Turkish remedy for kidney stones. With this study, we planned to evaluate the effects of CCog extract in ethylene glycol (EG)-induced nephrolithiasis model in rats.

METHODS

The study group comprised 32 Wistar albino rats which were divided into Control (C), EG, CCog Prophylaxis (CC+EG+CC), and CCog Treatment (EG+CC) groups. Stone formation was induced by adding EG (0.75%) into rat's drinking water. Normal drinking water was given to Control group for 8 weeks. Throughout the study period of 8 weeks, EG group was given only EG (0.75%) and CC+EG+CC group was given both EG and CCog. In EG+CC group, EG (0.75%) was given for 8 weeks whereas CCog was given for the past 4 weeks. After the 8th week, 24-h urine samples were collected. Rats were then sacrificed and kidney tissue samples were harvested.

RESULTS

Metabolites (calcium, citrate) and creatinine in 24 h urine samples were decreased in CC+EG+CC and EG+CC groups. While hyperoxaluria was observed in the EG group, oxalate levels were similar to control levels in the P-CCog and C-CCog groups. The N-acetyl-β-glucosaminidase and myeloperoxidase activities were both increased in EG group and these parameters were significantly decreased on CCog treatment.

CONCLUSION

We can conclude that C. coggygria extract can have beneficial effect on lowering concentration of stone-forming metabolites in urine and consequently protect renal tissues from damage due to nephrolithiasis. C. coggygria extract can be considered as a potential prophylactic and therapeutic option in high-risk stone formers. Furthermore, our data confirm ethnobotanical use of CC against nephrolithiasis.

Nephroprotective effect of PHYMIN-22 on ethylene glycol induced urolithiasis rat model

The present study was designed to evaluate the antiurolithiatic effect of PHYMIN-22 against ethylene glycol-induced urolithiasis in rats. Healthy Albino male rats with 200-230 g body weight were randomly divided into five groups, each with 5 animals, control group, EG group (0.75%), PHYMIN-22 treatment group (0.75% EG 14 days and 100 mg/kg PHYMIN-22 next 14 days), PHYMIN-22 drug control group (100 mg/kg) and cystone treatment group (0.75% EG 14 days and 750 mg/kg cystone next 14 days). Biochemical testing was adopted for measuring the blood and urine parameters, as well as the level of antioxidants including superoxide dismutase (SOD), Catalase (Cat), Glutathione peroxidase (GPx) and glutathione (GSH) in kidney tissues. Hematoxylin and eosin (HE) staining was utilized to observe the histopathological changes in the kidney tissue. End of the experiment the PHYMIN-22 treatment reduced the urine and serum calcium (p < 0.01; p < 0.01), oxalate (p < 0.01; p < 0.01), phosphate (p < 0.01; p < 0.01), uric acid (p < 0.001; p < 0.001), protein (p < 0.001; p < 0.001), and creatinine (p < 0.001; p < 0.001) respectively, serum indicators ALT (p < 0.001) and AST (p < 0.001) level and non-enzymic antioxidant GSH (p < 0.001) compared to EG induced urolithiasis animals (Diseased control group). PHYMIN-22 treatment significantly increased urine volume, pH, and body weight, and antioxidants include CAT (p < 0.001; p < 0.001), SOD (p ˃ 0.05; p < 0.05), and GPX (p < 0.01; p < 0.001) compared to Diseased control group animals. The effect of PHYMIN-22 on EG-induced urolithiasis animals could be by improving kidney function, normalizing the urine and serum parameters, maintaining the kidney antioxidants, eliminating crystal deposition, and excretion of unwanted ions from the kidney and urinary tract.

Proposal for pathogenesis-based treatment options to reduce calcium oxalate stone recurrence

Objective

Prevalence of kidney stone disease continues to increase globally with recurrence rates between 30% and 50% despite technological and scientific advances. Reduction in recurrence would improve patient outcomes and reduce cost and stone morbidities. Our objective was to review results of experimental studies performed to determine the efficacy of readily available compounds that can be used to prevent recurrence.

Methods

All relevant literature up to October 2020, listed in PubMed is reviewed.

Results

Clinical guidelines endorse the use of evidence-based medications, such as alkaline agents and thiazides, to reduce urinary mineral supersaturation and recurrence. However, there may be additional steps during stone pathogenesis where medications could moderate stone risk. Idiopathic calcium oxalate stones grow attached to Randall's plaques or plugs. Results of clinical and experimental studies suggest involvement of reactive oxygen species and oxidative stress in the formation of both the plaques and plugs. The renin-angiotensin-aldosterone system (RAAS), nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, mitochondria, and NOD-like receptor pyrin domain containing-3 (NLRP3) inflammasome have all been implicated at specific steps during stone pathogenesis in animal models.

Conclusion

In addition to supersaturation-reducing therapies, the use of anti-oxidants, free radical scavengers, and inhibitors of NADPH oxidase, NLRP3 inflammasome, and RAAS may prove beneficial for stone prevention. Compounds such as statins and angiotensin converting enzyme inhibitors are already in use as therapeutics for hypertension and cardio-vascular disease and have previously shown to reduce calcium oxalate nephrolithiasis in rats. Although clinical evidence for their use in stone prevention in humans is limited, experimental data support they be considered along with standard evidence-based medications and clinical expertise when patients are being counselled for stone prevention.

Anti-urolithiatic effect of Cucumis melo L. var inodorous in male rats with kidney stones

Melon seed extracts have high antioxidant activities and are effective against a variety of diseases, including kidney stones. In kidney stone model rats, the anti-urolithiatic effects of the hydro-ethanolic extract of melon seed and potassium citrate were studied and compared. After urolithiasis induction by ethylene glycol, the extract and potassium citrate were treated orally for 38 days concurrent with ethylene glycol. Then, urine and kidney sampling were done, and the urinary parameter levels were measured. The melon and potassium citrate treatments reduced the kidney index, the levels of urinary calcium and oxalate, calcium oxalate deposit numbers, the score of crystal deposits, histo-pathological damages, and the score of inflammation in the kidney sections, while elevating the urinary pH, magnesium, and citrate levels, and also the expression of the UMOD, spp1, and reg1 genes in the kidney of treated animals. The effect of potassium citrate is the same as the effect of melon in treated animals. So, their effects could be by normalizing urinary parameters, reducing crystal deposits, excreting small deposits from the kidney, reducing the chance of them being retained in the urinary tract, and elevating the expression of the UMOD, spp1, and reg1 genes, which are involved in kidney stone formation.

An insight investigation to the antiurolithic activity of Trachyspermum ammi using the in vitro and in vivo experiments

The crude extract of Trachyspermum ammi seeds (Ta.Cr) was studied for its antiurolithic activity using the in vivo and in vitro experiments. In the in vivo experiments, Ta.Cr treatment showed a diuretic activity at the dose of 30 and 100 mg/kg and exhibited curative effect in male hyperoxaluric Wistar rats, which received 0.75% ethylene glycol (EG) in drinking water given for 3 weeks, with 1% ammonium chloride (AC) for initial three days. In the in vitro experiments, Ta.Cr delayed the slopes of nucleation and inhibited the calcium oxalate (CaOx) crystal aggregation in a concentration-dependent manner like that of potassium citrate. Ta.Cr also inhibited DPPH free radicals like standard antioxidant drug butylated hydroxytoluene (BHT), and significantly reduced cell toxicity and LDH release in Madin-Darby canine kidney (MDCK) cells, exposed to oxalate (0.5 mM) and COM (66 µg/cm²) crystals. In isolated rabbit urinary bladder strips, Ta.Cr relaxed high K⁺ (80 mM) and CCh (1 µM)-induced contractions, showing antispasmodic activity. The findings of this study suggest that the antiurolithic activity of crude extract of Trachyspermum ammi seeds may be mediated by a number of mechanisms, including a diuretic, an inhibitor of CaOx crystal aggregation, an antioxidant, renal epithelial cell protection, and an antispasmodic, thus, showing the therapeutic potential in urolithiasis, for which there is no viable non-invasive option in modern medicine.

Cucumis callosus (Rottl.) Cogn. fruit extract ameliorates calcium oxalate urolithiasis in ethylene glycol induced hyperoxaluric Rat model

Cucumis callosus dry fruits are traditionally used as folk remedy to treat conditions like urethral irritations, urine stoppage or dribbling and other urinary ailments of man in north-west India. But no study is reported to validate this ethnic practice of using Cucumis fruit in urolithiasis. To evaluate anti-urolithiatic potential of Cucumis, hyperoxaluria was induced in rats by supplying 0.75% ethylene glycol (EG) + 1% ammonium chloride (AC) in drinking water for 14 days. Anti-urolithiatic activity of Cucumis callosus hydro-ethanolic extract (CCHEE) was assessed by measuring blood and urine biochemical parameters, oxidative stress indices, histopathology and osteopontin (OPN) expression. Administration of EG-AC to rats caused hyperoxaluria, crystalluria, azotaemia, oxidant/antioxidant imbalance (increase in lipid peroxidation (LPO), and decrease in glutathione (GSH) and catalase (CAT)), up-regulation of OPN and calcium oxalate (CaOx) crystal deposition in kidney. Treatment of afflicted rats with Cucumis fruits extract restored renal function to a great extent (CCHEE group), testified by improvement of stated parameters. Findings demonstrate curative efficacy of Cucumis fruit extract in EG induced urolithiasis of rats. The restoration of renal function was possibly by regulating renal stone formation via reducing urinary oxalate excretion, correcting oxidant/antioxidant imbalances, and reduced expression of OPN. Hence, results of this study validate the ethnic practice of using Cucumis fruit and conclude that fruit extracts have beneficial effects on CaOx urolithiasis and renal function.

Hyperoside Ameliorates Renal Tubular Oxidative Damage and Calcium Oxalate Deposition in Rats through AMPK/Nrf2 Signaling Axis

Background

Nephrolithiasis is a common disease that seriously affects the health and life quality of patients. Despite the reported effect of hyperoside (Hyp) against nephrolithiasis, the specific mechanism has not been clarified. Therefore, this study is aimed at investigating the effect and potential mechanism of Hyp on renal injury and calcium oxalate (CaOx) crystal deposition.

Methods

Rat and cell models of renal calculi were constructed by ethylene glycol (EG) and CaOx induction, respectively. The renal histopathological damage, CaOx crystal deposition, and renal function damage of rats were assessed by HE staining, Pizzolato staining, and biochemical detection of blood and urine parameters. MTT and crystal-cell adhesion assays were utilized to determine the activity of HK-2 cells and crystal adhesion ability, biochemical detection and enzyme-linked immunosorbent assay (ELISA) to measure the levels of oxidative stress-related substances and inflammatory factors, and western blot to test the expression levels of proteins related to the AMPK/Nrf2 signaling pathway.

Results

Briefly speaking, Hyp could improve the renal histopathological injury and impaired renal function, reduce the deposition of CaOx crystals in the renal tissue of rats with renal calculi, and decrease the adhesion of crystals to CaOx-treated HK-2 cells. Besides, Hyp also significantly inhibited oxidative stress response. Furthermore, Hyp was associated with the downregulation of malondialdehyde, lactate dehydrogenase, and reactive oxygen species and upregulation of superoxide dismutase activity. Additionally, Hyp treatment also suppressed inflammatory response and had a correlation with declined levels of interleukin (IL)-1β, IL-6, IL-8, and tumor necrosis factor. Further exploration of mechanism manifested that Hyp might play a protective role through promoting AMPK phosphorylation and nuclear translation of Nrf2 to activate the AMPK/Nrf2 signaling pathway.

Conclusion

Hyp can improve renal pathological and functional damage, decrease CaOx crystal deposition, and inhibit oxidative stress and inflammatory response. Such effects may be achieved by activating the AMPK/Nrf2 signaling pathway.

Comparison of cat and human calcium oxalate monohydrate kidney stone matrix proteomes

Despite its critical nature, the role of matrix in calcium oxalate stone formation is poorly understood. The wide diversity of proteins comprising matrix has contributed to the ambiguity. This study compares the protein distributions measured by mass spectrometry in human calcium oxalate stone matrix to that observed in cat stone matrix, because cats share many clinical characteristics of their stone disease with humans. The observed protein distributions were analyzed in the context of a recent model based on the aggregation of strongly anionic and strongly cationic proteins which includes selective adsorption of other proteins based on total charge. Matrix protein distributions shared many common features between species, including enrichment of both strongly anionic and strongly cationic proteins, increased total charge in matrix proteins compared to urine proteins, and a high degree of similarity of prominent strongly anionic proteins in the matrix of both species. However, there was weaker overlap of the specific dominant proteins in other regions of the net charge distribution. Collectively, these observations support the conceptual model where the strongly anionic proteins associate most strongly with the calcium oxalate crystal surfaces, while the other proteins associate with the strongly anionic proteins through non-specific, charge interactions with each other to create stones. Also, cats appear to be the best animal model of human stone disease identified to date based on these similarities.

Hyperoxaluria Induces Endothelial Dysfunction in Preglomerular Arteries: Involvement of Oxidative Stress

Urolithiasis is a worldwide problem and a risk factor for kidney injury. Oxidative stress-associated renal endothelial dysfunction secondary to urolithiasis could be a key pathogenic factor, similar to obesity and diabetes-related nephropathy. The aim of the present study was to characterize urolithiasis-related endothelial dysfunction in a hyperoxaluria rat model of renal lithiasis. Experimental approach: Endothelial dysfunction was assessed in preglomerular arteries isolated from control rats and in which 0.75% ethylene glycol was administered in drinking water. Renal interlobar arteries were mounted in microvascular myographs for functional studies; superoxide generation was measured by chemiluminescence and mRNA and protein expression by RT-PCR and immunofluorescence, respectively. Selective inhibitors were used to study the influence of the different ROS sources, xanthine oxidase, COX-2, Nox1, Nox2 and Nox4. Inflammatory vascular response was also studied by measuring the RNAm expression of NF-κB, MCP-1 and TNFα by RT-PCR. Results: Endothelium-dependent vasodilator responses were impaired in the preglomerular arteries of the hyperoxaluric group along with higher superoxide generation in the renal cortex and vascular inflammation developed by MCP-1 and promoted by NF-κB. The xanthine oxidase inhibitor allopurinol restored the endothelial relaxations and returned superoxide generation to basal values. Nox1 and Nox2 mRNA were up-regulated in arteries from the hyperoxaluric group, and Nox1 and Nox2 selective inhibitors also restored the impaired vasodilator responses and normalized NADPH oxidase-dependent higher superoxide values of renal cortex from the hyperoxaluric group. Conclusions: The current data support that hyperoxaluria induces oxidative stress-mediated endothelial dysfunction and inflammatory response in renal preglomerular arteries which is promoted by the xanthine oxidase, Nox1 and Nox2 pathways.

Pharmacological Evaluation of Mentha piperita Against Urolithiasis: An In Vitro and In Vivo Study

Background: Mentha piperita L. (peppermint) is one of the most widely consumed medicinal herbs that has gained attention from food and pharmaceutical industries due to its distinct aroma and taste. Purpose: Present study was aimed to rationalize the traditional use of peppermint in urolithiasis and to explore its possible underlying mechanism. Research Design: The aqueous methanolic crude extract of Mentha piperita (Mp.Cr) was assessed for phytochemical constituents and antioxidant activity. In vitro crystallization assays were performed to determine the inhibitory effects of Mp.Cr against crystal nucleation, aggregation and growth. In vivo urolithiasis model was developed in rats by the administration of ammonium chloride and ethylene glycol in drinking water. The antiurolithic effects of Mp.Cr were evaluated by analyzing kidney homogenate, biochemical and histological parameters. Results: HPLC analysis showed the presence of epicatechin, quercetin, gallic acid, syringic acid, kaempferol, caffeic acid and coumaric acid. The maximum quantity of quercetin equivalent flavonoid and gallic acid equivalent phenolic content was found to be 63.73 ± .24 mg QE/g and 43.76 ± .6 mg GAE/g of Mp.Cr, respectively. Mp.Cr significantly normalized urinary and serum biochemistry, similar to the standard cystone treatment. Conclusions: The current study validated the preventive and curative potential of Mp.Cr against urolithiasis and justified its traditional use in kidney stone disease.

Relationship Between Serum Testosterone Levels and Kidney Stones Prevalence in Men

BACKGROUND

The role of serum testosterone levels in male renal stone formation remains controversial. This study aimed to evaluate the relationship between serum testosterone levels and kidney stone prevalence in males.

METHODS

We conducted a cross-sectional study based on the data from the National Health and Nutrition Examination Survey 2011-2016, which included 6,633 male participants, to investigate the association between testosterone levels and the prevalence of kidney stones.

RESULTS

In this study, using the highest quartile of serum testosterone as a reference, a logistic regression model adjusted for confounders in all participants showed that the first quartile (OR: 1.375, p = 0.016), the second quartile (OR: 1.348, p = 0.021), and the third quartile (OR: 1.472, p = 0.003) of testosterone significantly increased kidney stone risks. In the 41-60 age group, the ORs of kidney stone risk in the first, second, and third of serum testosterone were 1.904 (P = 0.005), 1.599 (P = 0.040), and 1.734 (P = 0.015), respectively. This trend can also be found in the 61-80-year group, except in the first quartile of serum testosterone (OR: 1.169, P = 0.436). Adjusted smoothed curves suggest a non-linear relationship between the 8 quantiles of serum testosterone and the risk of kidney stones in all participants and the 61-80 age group and a significant negative relationship in the 41-60 age group (OR: 0.921, P = 0.0193). But no correlation was seen in the 20-40 group.

CONCLUSIONS

Serum testosterone levels were significantly inversely associated with the prevalence of kidney stones in men over 40 years of age, but no correlation was seen in the 20-40 group. The role of testosterone in stone formation should be redefined, and its effect should be further verified.

Prediction of the occurrence of calcium oxalate kidney stones based on clinical and gut microbiota characteristics

Purpose

To predict the occurrence of calcium oxalate kidney stones based on clinical and gut microbiota characteristics.

Methods

Gut microbiota and clinical data from 180 subjects (120 for training set and 60 for validation) attending the West China Hospital (WCH) were collected between June 2018 and January 2021. Based on the gut microbiota and clinical data from 120 subjects (66 non-kidney stone individuals and 54 kidney stone patients), we evaluated eight machine learning methods to predict the occurrence of calcium oxalate kidney stones.

Results

With fivefold cross-validation, the random forest method produced the best area under the curve (AUC) of 0.94. We further applied random forest to an independent validation dataset with 60 samples (34 non-kidney stone individuals and 26 kidney stone patients), which yielded an AUC of 0.88.

Conclusion

Our results demonstrated that clinical data combined with gut microbiota characteristics may help predict the occurrence of kidney stones.

6-Shogaol attenuated ethylene glycol and aluminium chloride induced urolithiasis and renal injuries in rodents

The 6-shogaol, is a flavanone type flavonoid that is abundant in citrus fruit and has a wide range of pharmacological effects. The present study attempted to evaluate the antiurolithic effect of 6-shogaol on ethylene glycol (EG) and ammonium chloride (AC)-induced experimental urolithiasis in rats. The efficacy of 6-shogaol 50 mg/kg and 100 mg/kg was studied in EG 0.75% (V/V) and AC 1% (W/V) experimentally induced urolithiasis in rats for 21 days. The weight difference, urine volume, the levels of calcium, phosphate, magnesium, oxalate and uric acid in urine was observed. The blood urea nitrogen, creatinine, uric acid in serum and levels of malondialdehyde (MDA) and glutathione (GSH) were also measured. Histopathological analyses in kidneys were also performed. The rats weights were higher in the 6-shogaol groups than the urolithiasis group. EG caused a significant increase in serum creatinine (p < 0.05), BUN (P < 0.001), and uric acid (p < 0.01) while treatment with Cystone (750 mg/kg), and 6-shogaol (50 and 100 mg/kg) showed the significant reduction in increased serum levels of creatinine (p < 0.001), uric acid (p < 0.01) and BUN (p < 0.001). Administration of EG and AC showed statistically significant (p < 0.001) elevated levels of MDA and reduction in GSH levels. Treatment of Cystone (750 mg/kg), and 6-shogaol (50 and 100 mg/kg) significantly (p < 0.001) reduced MDA levels and an increase GSH levels as compared to EG and AC-treated group. The histological findings further attested antiurolithiatic properties of 6-shogaol. The present study attributed clinical shreds of evidence first time that claiming the significant antiurolithic effect of 6-shogaol and could be a cost-effective candidate for the prevention and treatment of urolithiasis.

Effects of high-sodium diet on lithogenesis in a rat experimental model of calcium oxalate stones

Background

This study aimed to investigate the effects of a high- and low-sodium diets on lithogenesis in a rat experimental model of calcium oxalate stones.

Methods

Twenty male Wistar rats were randomly divided into four groups; group A: 4% NaCl+1% ethylene glycol (EG); group B: 8% NaCl+1% EG; group C: 8% NaCl+normal drinking-water; group D: 1% EG +normal diet. All rats were sacrificed 4 weeks later, and blood samples were collected from the heart. The kidneys were collected for Von Kossa staining to evaluate the formation of calcium-containing crystals. The last 24-h urine samples were also gathered for metabolic analysis.

Results

Von Kossa staining demonstrated that the rats in both group A and group B had significantly more renal calcium crystals than those in group D. However, 24-h urinary volume increased significantly (142.26±20.91 mL) in group B compared with group A (100.52±28.23 mL), group C (107.36±14.24 mL), group D (40.79±8.71 mL) (P=0.004, 0.012, and 0.000 respectively). Level of urine sodium (Na), potassium (K), chlorine (Cl), and calcium (Ca), urea nitrogen were significantly higher in group B compared with group D. The urine phosphorus, oxalate, and creatinine levels; urine specific gravity; and urine PH were similar between group B and group D. The level of serum sodium was higher in group B (151.26±4.06 mmol/L) compared with group D (145.56±1.12 mmol/L) (P=0.002).

Conclusions

A high sodium intake might increase the risk of lithogenesis in susceptible individuals (given by EG) or in individuals with water restriction.

Antiurolithic effects of medicinal plants: results of in vivo studies in rat models of calcium oxalate nephrolithiasis-a systematic review

Urolithiasis is one of the oldest diseases affecting humans, while plants are one of our oldest companions providing food, shelter, and medicine. In spite of substantial progress in understanding the pathophysiological mechanisms, treatment options are still limited, often expensive for common people in most parts of the world. As a result, there is a great interest in herbal remedies for the treatment of urinary stone disease as an alternative or adjunct therapy. Numerous in vivo and in vitro studies have been carried out to understand the efficacy of herbs in reducing stone formation. We adopted PRISMA guidelines and systematically reviewed PubMed/Medline for the literature, reporting results of various herbal products on in vivo models of nephrolithiasis/urolithiasis. The Medical Subject Heading Terms (Mesh term) "Urolithiasis" was used with Boolean operator "AND" and other related Mesh Unique terms to search all the available records (July 2019). A total of 163 original articles on in vivo experiments were retrieved from PubMed indexed with the (MeshTerm) "Urolithiasis" AND "Complementary Therapies/Alternative Medicine, "Urolithiasis" AND "Plant Extracts" and "Urolithiasis" AND "Traditional Medicine". Most of the studies used ethylene glycol (EG) to induce hyperoxaluria and nephrolithiasis in rats. A variety of extraction methods including aqueous, alcoholic, hydro-alcoholic of various plant parts ranging from root bark to fruits and seeds, or a combination thereof, were utilized. All the investigations did not study all aspects of nephrolithiasis making it difficult to compare the efficacy of various treatments. Changes in the lithogenic factors and a reduction in calcium oxalate (CaOx) crystal deposition in the kidneys were, however, considered favorable outcomes of the various treatments. Less than 10% of the studies examined antioxidant and diuretic activities of the herbal treatments and concluded that their antiurolithic activities were a result of antioxidant, anti-inflammatory, and/or diuretic effects of the treatments.

Nephroprotective Effect of Pleurotus ostreatus and Agaricus bisporus Extracts and Carvedilol on Ethylene Glycol-Induced Urolithiasis: Roles of NF-κB, p53, Bcl-2, Bax and Bak

This study was designed to assess the nephroprotective effects of Pleurotus ostreatus and Agaricus bisporus aqueous extracts and carvedilol on hyperoxaluria-induced urolithiasis and to scrutinize the possible roles of NF-κB, p53, Bcl-2, Bax and Bak. Phytochemical screening and GC-MS analysis of mushrooms’ aqueous extracts were also performed and revealed the presence of multiple antioxidant and anti-inflammatory components. Hyperoxaluria was induced in Wistar rats through the addition of 0.75% (v/v) ethylene glycol in drinking water for nine weeks. The ethylene glycol-administered rats were orally treated with Pleurotus ostreatus and Agaricus bisporus aqueous extracts (100 mg/kg) and carvedilol (30 mg/kg) daily during the last seven weeks. The study showed that Pleurotus ostreatus, Agaricus bisporus and carvedilol all successfully inhibited ethylene glycol-induced histological perturbations and the elevation of serum creatinine, serum urea, serum and urinary uric acid, serum, urinary and kidney oxalate, urine specific gravity, kidney calcium, kidney NF-κB, NF-κB p65, NF-κB p50, p53, Bax and Bak expressions as well as serum TNF-α and IL-1β levels. Moreover, the treatment decreased the reduction in urinary creatinine, urinary urea, ratios of urinary creatinine to serum creatinine and urinary urea to serum urea, Fex Urea and Bcl-2 expression in kidney. In conclusion, although Pleurotus ostreatus and Agaricus bisporus extracts and carvedilol all significantly inhibited the progression of nephrolithiasis and showed nephroprotective effects against ethylene glycol-induced kidney dysfunction, Pleurotus ostreatus and Agaricus bisporus seemed to be more effective than carvedilol. Moreover, the nephroprotective effects may be mediated via affecting NF-κB activation, extrinsic apoptosis and intrinsic apoptosis pathways.

Effect of Macrotyloma uniflorum in ethylene glycol induced urolithiasis in rats

Macrotyloma uniflorum Linn. (Fabaceae) seeds are widely used for their diuretic and urolithiatic effects in India. The present study investigated the effect of aqueous extract of Macrotyloma uniflorum seeds (AEMU) on ethylene glycol induced urolithiasis in rats. To induce urolithiasis, 0.75% v/v ethylene glycol was administered orally for 14 days. The curative doses of 400 and 800 mg/kg were administered from 15^th to 28^th day. On the 28th day, 24 h urine, serum was collected and various biochemical parameters were estimated in urine, serum and kidney homogenate along with histology of kidney. Co-administration of AEMU with ethylene glycol has significantly (p < 0.001) increased the urine volume and the level of calculus inhibitors like magnesium, citrate and decreased the level of calculus promoters like calcium, oxalate, uric acid and urea also decreased in crystalluria in urine. AEMU supplement also prevented the pathological changes in the kidney and increased the glomerulus activity of the kidney. These results indicate that AEMU showed significant activity in urolithiasis which might be due to its diuretic, calcium oxalate crystal formation inhibitory effects and its ability to increase the levels of inhibitors and decrease the level of promoters of urolithiasis.

Hexametaphosphate as a potential therapy for the dissolution and prevention of kidney stones

The incidence of kidney stones is increasing worldwide, and recurrence is common (50% within 5 years). Citrate, the current gold standard therapy, which is usually given as potassium or sodium salts, is used because it raises urine pH and chelates calcium, the primary component of up to 94% of stones. In this study hexametaphosphate (HMP), a potent calcium chelator, was found to be 12 times more effective at dissolving calcium oxalate, the primary component of kidney stones, than citrate. HMP was also observed to be effective against other common kidney stone components, namely calcium phosphate and struvite (magnesium ammonium phosphate). Interestingly, HMP was capable of raising the zeta potential of calcium oxalate particles from -15.4 to -34.6 mV, which may prevent stone growth by aggregation, the most rapid growth mechanism, and thus avert occlusion. Notably, HMP was shown to be up to 16 times as effective as citrate at dissolving human kidney stones under simulated physiological conditions. It may thus be concluded that HMP is a promising potential therapy for calcium and struvite kidney stones.

Effect of endoplasmic reticulum stress-mediated excessive autophagy on apoptosis and formation of kidney stones

AIMS

This study was designed to reveal the role and underlying mechanism of excessive autophagy mediated by ERS via the PERK-eIF2α pathway in the apoptosis and formation of CaOx kidney stones.

MAIN METHODS

Ethylene glycol (EG) was used to establish a rat model of CaOx kidney stones, and 100 mg/kg of ERS inhibitor 4-phenylbutyric acid (4-PBA) or 60 mg/kg of autophagy inhibitor chloroquine (CQ) was administered daily to the rats. Four weeks after administration, we collected blood and kidney tissues to analyze the occurrence of ERS and autophagy, apoptosis, renal function, renal tubular crystal deposition, and kidney damage, respectively.

KEY FINDINGS

We observed that both 4-PBA and CQ treatment significantly inhibited the excessive autophagy and reduced apoptosis as well as decreasing p-PERK and p-eIF2α expressions. Meanwhile, the proportion of kidney weight, contents of creatinine and blood urea nitrogen, excretion of neutrophil gelatinase-associated lipocalin and kidney injury molecule 1, and renal tubular deposition were markedly down-regulated.

SIGNIFICANCE

The findings in this study suggested that ERS induced excessive autophagy via the PERK-eIF2α pathway, regulating cell damage and apoptosis. ERS-mediated inhibition of excessive autophagy effectively protected kidney function and prevented the apoptosis and formation of kidney stones.

Anticalcifying effect of Daucus carota in experimental urolithiasis in Wistar rats

Background

Urolithiasis is a burgeoning disease that results from pathological biomineralization. Daucus carota L. is a widely consumed food crop with reported nephroprotective and diuretic activity. Its potential for Ashmari bhedan (destruction of stone/calculi) or treatment of urinary calculi has been explored traditionally. However, no scientific evidence is available to prove its antiurolithiatic efficacy. Moreover, establishing the antiurolithiatic effects of D. carota, an extensively consumed commodity with numerous health benefits, would provide a beneficial dietary measure for the prevention and cure of urolithiasis.

Objective

The study aimed at investigating in vivo antiurolithiatic potential of hydroethanolic extract of D. carota roots against calcium oxalate urolithiasis.

Materials and methods

Ethylene glycol and ammonium chloride induced hyperoxaluria model of urolithiasis in male Wistar rats was used for the study. Urine and serum parameters and, kidney histopathology was used to determine the antilithic efficacy of D. carota root extract.

Results

D. carota extract significantly ameliorated abnormal urinary levels of calcium, oxalate, phosphate, magnesium, citrate, protein and uric acid in lithogenic rats. Serum BUN, creatinine and uric acid levels; and calcium, phosphate and oxalate deposition in kidney tissue were also rendered normal following D. carota treatment. D. carota extract also prevented oxidative stress mediated renal tissue degeneration both prophylactically and curatively.

Conclusion

This study suggests antiurolithiatic effect of D. carota roots, which can be attributed to its anticrystallization property, ability to ameliorate urine and serum biochemistry and renal cellularity.

Oxalate induces type II epithelial to mesenchymal transition (EMT) in inner medullary collecting duct cells (IMCD) in vitro and stimulate the expression of osteogenic and fibrotic markers in kidney medulla in vivo

EMT occurs in response to a number of stresses conditions as mechanical stretch, cancer, hypoxia, oxidative stress (ROS), among others. EMT describes a phenotypical change induced in epithelial cells. It is characterized by increases in motility, extracellular matrix synthesis, proliferation, and invasiveness. The present study analyzed if oxalate ions (Ox) could induce EMT in IMCD cells. Ox (0.5 mM) and transforming growth factor beta (TGF-β1 20 ng/mL) exposition during 48 hours increased migration and invasiveness, increased mesenchymal marker expression (Vimentin, alpha-smooth muscle actin: α-SMA, TGF-β1) and decreased epithelial marker expression (E-cadherin). IMCD stimulated with Ox and TGF-β1 and then exposed to the osteogenic medium during 15 days significantly increased early osteogenic markers (RUNX-2 and Alkaline Phosphatase) expression. Hyperoxaluric mice fed with trans-4-hydroxy-L-proline (HPL) presented calcium oxalate crystal excretion, increased in TGF-β1 expression and collagen fibers deposition and increased early osteogenic markers (RUNX-2 and Alkaline Phosphatase) at 60 days. Our in vitro and in vivo results suggest that oxalate induces EMT in inner medulla collecting duct cells and it may be involved in fibrotic tissue development, osteogenic differentiation and calcium crystal production both implicated in nephrolithiasis.

Protective potential of Angelica sinensis polysaccharide extract against ethylene glycol-induced calcium oxalate urolithiasis

Purpose: To evaluate a Angelica sinensis polysaccharide aqueous extract as a preventive agent in experimentally induced urolithiasis using in- vitro and vivo models.

Material and methods:Angelica sinensis polysaccharide was investigated in vitro to determine its antilithiatic effects on the formation and morphology of calcium oxalate (CaOx) crystals and was analyzed in vivo to determine its ability to prevent CaOx urolithiasis in rats subjected to ethylene glycol-induced urolithiasis. Potassium citrate administration was used in the positive control group. The urolithiasis-related biochemical parameters were evaluated in the rats urine, serum and kidney homogenates. Kidney sections were subjected to histopathological and immunohistochemical analyses, and urolithiasis-related phospho-c-Jun NH2-terminal protein kinase and kidney injury molecule-1proteins were evaluated by Western blot analyses.

Results:Angelica sinensis polysaccharide exhibited concentration-dependent inhibition of CaOx crystal formation. The in vitro assay revealed significant inhibition of crystal formation (6.99 ± 1.07) in the group treated with 4.0 mg/mL Angelica sinensis polysaccharide extract compared with the control group (58.38 ± 5.63; p < .05). In vivo, after treatment with ethylene glycol for 28 days, urinary oxidative stress, oxalate, creatinine, urea and urolithiasis-related protein were significantly increased (p < .05), except for serum oxidative stress (p > .05). The rats administered the extract of Angelica sinensis polysaccharide showed significantly decreased pathological change and CaOx deposition (p < .05) compared with the urolithiatic rats. Significantly reduced levels of urinary oxidative stress, oxalate, creatinine, urea and urolithiasis-related protein were observed in the Angelica sinensis polysaccharide treatment groups (p < .05) compared with the nephrolithic rats.

Conclusion: The results presented here suggest that Angelica sinensis polysaccharide has the potential to inhibit CaOx crystallization in vitro and may present anti-urolithiatic effects in vivo.

Drosophila melanogaster as a function-based high-throughput screening model for antinephrolithiasis agents in kidney stone patients

Kidney stone disease involves the aggregation of stone-forming salts consequent to solute supersaturation in urine. The development of novel therapeutic agents for this predominantly metabolic and biochemical disorder have been hampered by the lack of a practical pre-clinical model amenable to drug screening. Here, Drosophila melanogaster, an emerging model for kidney stone disease research, was adapted as a high-throughput functional drug screening platform independent of the multifactorial nature of mammalian nephrolithiasis. Through functional screening, the therapeutic potential of a novel compound commonly known as arbutin that specifically binds to oxalate, a key component of kidney calculi, was identified. Through isothermal titration calorimetry, high-performance liquid chromatography and atomic force microscopy, arbutin was determined to interact with calcium and oxalate in both free and bound states, disrupting crystal lattice structure, growth and crystallization. When used to treat patient urine samples, arbutin significantly abrogated calculus formation in vivo and outperformed potassium citrate in low pH urine conditions, owing to its oxalate-centric mode of action. The discovery of this novel antilithogenic compound via D. melanogaster, independent of a mammalian model, brings greater recognition to this platform, for which metabolic features are primary outcomes, underscoring the power of D. melanogaster as a high-throughput drug screening platform in similar disorders. This is the first description of the use of D. melanogaster as the model system for a high-throughput chemical library screen. This article has an associated First Person interview with the first authors of the paper.

Downregulated Expression of Solute Carrier Family 26 Member 6 in NRK-52E Cells Attenuates Oxalate-Induced Intracellular Oxidative Stress

Solute carrier family 26 member 6 (Slc26a6), which is mainly expressed in the intestines and kidneys, is a multifunctional anion transporter that is crucial in the transport of oxalate anions. This study is aimed at investigating the effect of Slc26a6 expression on oxalate-induced cell oxidation and crystal formation. Lentivirus transfection was used to upregulate or downregulate Slc26a6 expression in NRK cells. Cell viability and apoptosis, reactive oxygen species (ROS) and malondialdehyde (MDA) generation, and superoxide dismutase (SOD) activity were measured. Crystal adhesion and the cell ultrastructure were observed using light and transmission electron microscopy (TEM). Three groups of rats, normal control, lentivirus-vector, and lentivirus-small interfering RNA (lv-siRNA) groups, were used, and after lentivirus transfection, they were fed 1% ethylene glycol (EG) and 0.5% ammonium chloride (NH₄Cl) for 2 weeks. Dihydroethidium (DHE), terminal deoxynucleotidyl transferase (TdT) deoxyuridine dUTP nick-end labeling (TUNEL), and von Kossa staining were performed, and nuclear factor κB (NFκB) and osteopontin (OPN) expression were measured. In the vitro study, compared to the control group, downregulated Slc26a6 NRK cells showed alleviation of the cell viability decrease, cell apoptosis rate, ROS generation, and SOD activity decrease after oxalate treatment. Crystal adhesion and vesicles were significantly less after oxalate exposure than in the untreated controls. Rats infected with lentivirus-siRNA exhibited attenuated SOD generation, cell apoptosis, and crystal formation in the kidneys. Increased phosphorylation of NFκB and OPN was involved in the pathological process. In conclusion, the results of the present study indicate that reducing the expression of Slc26a6 in the kidney may be a potential strategy for preventing stone formation.

Crystal growth, a research-driven laboratory course

The research-driven laboratory experiment described herein has at its core the individual development of students, combining core subject matter with the opportunity to explore, in a research environment, areas outside of traditional curricula; however, it maintains the pedagogical training for an undergraduate major degree in chemistry and sciences in general. The laboratory can feasibly be implemented in high schools to expose students to an engaging and intellectually fulfilling aspect of chemistry early in their career. This seven-week project is based on the growth and study of crystals and encourages students, from the outset, to conceive, propose, design, plan and carry out their own research on chemicals and conditions of their own choosing. The wide array of laboratory equipment, analytical instrumentation and techniques that the students are potentially exposed to, from micropipettes and optical microscopes to scanning electron microscopy and powder X-ray diffraction, puts these projects on a par with senior capstone research projects. The feedback from the students for the seven years this project has been in operation is almost unanimous in enthusiasm and praise.

Effect of Piper cubeba L. fruit on ethylene glycol and ammonium chloride induced urolithiasis in male Sprague Dawley rats

Background

To investigate the antilithiatic effect of hydroalcoholic extract of Kabab Chini (Piper cubeba L.) fruit in male Sprague Dawley rats.

Methods

Rats were divided into six groups of six each. Group I received regular rat food and drinking water ad libitum. Groups II to VI were administered with ethylene glycol (EG) 0.75% (V/V) and ammonium chloride (AC) 1% (W/V) in drinking water for 7 days to induce urolithiasis. From 8th day Group I received 1 mL of 5% gum acacia. Group IV was treated with Cystone; V and VI groups with the hydro-alcoholic extract of Piper cubeba L. Treatment was continued for further 14 days, thereafter animals sacrificed. While Group II animals were sacrificed just after 7 days treatment with EG and AC. Group III was left untreated until 14 days and sacrificed on 22nd day. Crystalluria was analyzed on 8th and 22nd day while, urinary calcium, phosphorus, creatinine, sodium and magnesium on 22nd day. Biochemistry and histopathological studies of kidney were also carried out.

Results

Test groups showed significant reduction (p < 0.001) of crystals in urine. Serum creatinine and urea (p < 0.01) were also decreased significantly. Urine analysis showed significant increase in magnesium while calcium, sodium, chloride and phosphorus significantly decreased along with histopathological improvement in kidney tissue in treated groups.

Conclusion

From the above results it can be concluded that hydroalcoholic extract of P. cubeba L. fruit has significant inhibitory effect in calcium oxalate urolithiasis.

In vitro and in vivo models for the study of urolithiasis

Preclinical animal research has greatly contributed and will continue to contribute in our understanding of various disease states and provided methods for more understanding of disease states and designs to test novel pharmaco-therapeutic interventions against these diseases. For urolithiasis, scientists have developed numerous in vitro and in vivo models that attempt to replicate human urolithiasis. In this review, I have explained in vitro and in vivo models that are more common, affordable, and easy to replicate. In the in vitro models, I have focused on the CaOx crystallization models and in the in vivo models, hyperoxaluric rat model has been explained along with other available option such as Knockout (KO) mice and fly models. Each model has been explained stepwise along with its pros and cons.

Changes of Klotho protein and Klotho mRNA expression in a hydroxy-L-proline induced hyperoxaluric rat model

Klotho protein is recognized as having a renoprotective effect and is used as a biomarker for kidney injury. We investigated the level of Klotho protein in hyperoxaluria-induced kidney injury and the effects of vitamin E (Vit E) and vitamin C (Vit C) supplementation. Hyperoxaluria was induced by feeding 2% (w/v) Hydroxy-L-proline (HLP) in the drinking water for 21 days. Rats were divided into 5 groups; control (Group 1, n=7), HLP treated rats that received nothing else (Group 2, n=7), Vit E (Group 3, n=6), Vit C (Group 4, n=6) and both Vit E and Vit C (Group 5, n=7). Vit E (200 mg/kg) was injected on days 1, 6, 11 and 16, while Vit C (500 mg/kg) was given intravenously on days 1 and 11. The Klotho protein levels and oxidative status were measured. The expression level of kidney Klotho protein expression was significantly reduced by HLP-treatment, while the mRNA expression was higher (P<0.05), the plasma and kidney malondialdehyde and kidney superoxide dismutase activities were increased, and the kidney reduced glutathione and urinary total antioxidant status were decreased (P<0.05). All of these changes were ameliorated by administration of Vit E, Vit C or especially the co-administration of both. In conclusion, HLP-induced hyperoxaluria reduced the kidney Klotho protein level, which could be restored by Vit E and/or Vit C.

Transcriptional study of hyperoxaluria and calcium oxalate nephrolithiasis in male rats: Inflammatory changes are mainly associated with crystal deposition

Hyperoxaluria associated with renal deposition of calcium oxalate (CaOx) crystals causes renal injury and inflammation leading to number of diseases including chronic kidney disease (CKD). It is however, not been possible to separate the renal consequences of hyperoxaluria from that of CaOx crystal deposition. We decided to utilize ethylene glycol (EG) model where hyperoxaluria and CaOx crystal deposition can be separated in time. To test our hypothesis, male rats were made hyperoxaluric by administering EG, rats were euthanized and kidneys were extracted on day 14, when occasional crystal is seen in the kidneys and day 28, when all animals have developed renal CaOx crystal deposits. Total RNA was extracted for microarray analysis and genome wide analysis of differentially expressed genes was performed to investigate differences between hyperoxaluria and crystal induced alterations in the kidneys. Immunohistochemical and Hematoxylin and Eosin (H&E) staining was also done for macromolecules with significant role in stone formation. All EG fed rats became hyperoxaluric by day 7, showed a few crystal deposits on day 14, and had heavy crystal deposition by day 28. There were significant changes in the expression of genes encoding for NADPH Oxidases; macromolecular crystallization modulators; genes involved in inflammasome activation; and osteogenic marker genes. Results demonstrate major differences between hyperoxaluria and CaOx crystal induced changes in the kidneys. Injury and inflammation are mainly associated with crystal deposition indicating significant role played by crystal retention.

Metabolic syndrome contributes to renal injury mediated by hyperoxaluria in a murine model of nephrolithiasis

Metabolic syndrome (MS) individuals have a higher risk of developing chronic kidney disease through unclear pathogenic mechanisms. MS has been also related with higher nephrolithiasis prevalence. To establish the influence of MS on renal function, we designed a murine model of combined metabolic syndrome and hyperoxaluria. Four groups of male Sprague-Dawley rats were established: (1) control group (n = 10) fed with standard chow; (2) stone former group (SF) (n = 10) fed with standard chow plus 0.75% ethylene glycol administered in the drinking water; (3) metabolic syndrome group (MS) (n = 10), fed with 60% fructose diet; (4) metabolic syndrome + stone former group (MS + SF) (n = 10), 60% fructose diet and 0.75% EG in the drinking water. MS group showed a significant injury to renal function when hyperoxaluria was induced. It was demonstrated by a significant decrease of creatinine clearance (p < 0.001), with higher tubular damage (34.3%, CI 95% 23.9-44.7, p < 0.001), produced by deposition of crystals, and increased tubular synthesis of osteopontin as a response to tubular damage. Induction of hyperoxaluria in rats with MS causes severe morphological alterations with a significant impairment of renal function. This impairment is not produced in rats without MS. Therefore, this model can be useful for the study of the influence of MS in stone formation.

Inhibitory effect of an aqueous extract of Radix Paeoniae Alba on calcium oxalate nephrolithiasis in a rat model

Objective: To examine the effect of an aqueous extract of Radix Paeoniae Alba (RPA) on the formation of calcium oxalate (CaOx) stones and the potential mechanism underlying the effect.

Materials and methods: An in vitro assay was used to determine whether the RPA extract prevents the formation of CaOx or promotes CaOx dissolution. We also investigated the efficacy of the extract in vivo as a preventive and therapeutic agent for experimentally induced CaOx nephrolithiasis in rats. Various biochemical, molecular, and histological parameters were assessed in kidney tissue and urine at the end of the in vivo experiment.

Results: Significant dissolution of formed crystals (8.99 ± 1.43) and inhibition of crystal formation (2.55 ± 0.21) were observed in vitro after treatment with 64 mg/mL of the RPA extract compared with a control treatment (55.10 ± 4.98 and 54.57 ± 5.84, respectively) (p < .05). In preventive protocols, the RPA extract significantly reduced urinary and renal oxalate levels and increased urinary calcium and citrate levels compared to the control. In addition, the RPA preventive protocol significantly decreased osteopontin expression, renal crystallization, and pathological changes compared to the control. These changes were not observed in rats on the therapeutic protocol.

Conclusions: RPA is a useful agent that prevents the formation of CaOx kidney stones.

Antilithiatic effect of Peucedanum grande C. B. Clarke in chemically induced urolithiasis in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Duqu (Peucedanum grande C. B. Clarke) has been used by Unani physicians since ancient times in retention of urine, renal and bladder calculi, nephritis and other associated disorders in different dosage forms.

AIM OF THE STUDY

The aim of the study was to evaluate the antiurolithiatic activity of Peucedanum grande C. B. Clarke in experimental model.

MATERIALS AND METHODS

The experiment was carried out in male Sprague Dawley rats divided into 5 groups of 8 animals each. Animals of negative control received 1ml of 5% Gum acacia throughout the study. Remaining four groups received Ethylene glycol 0.75% and Ammonium chloride 1% by adding in their drinking water for first seven days to induce urolithiasis. From 8th day, positive control received 1ml of 5% Gum acacia, standard control received Cystone in the dose of 750mg/kg while test groups A and B were treated with hydroalcoholic extract of test drug in the dose of 56mg/kg and 97mg/kg respectively up to 21 days, thereafter the animals were sacrificed. Number of CaOx crystals in urine, levels of serum calcium, phosphorus, creatinine, urea, urinary calcium and sodium were observed. Kidney homogenate analysis and histopathology were also carried out.

RESULTS

Test drug reduced number of CaOx crystals in urine (p<0.001); levels of serum calcium, phosphorus, creatinine, (p<0.001) urea, (p<0.05); urinary calcium (p<0.001) and sodium decreased significantly in standard and test groups. The urine volume increased significantly (p<0.05, 0.01) in both the test groups. Histopathology of kidney showed no CaOx crystal deposition in both the test groups.

CONCLUSION

On the basis of above findings, it can be concluded that the test drug possesses significant antiurolithiatic activity.

Alteration in Oxidative/nitrosative imbalance, histochemical expression of osteopontin and antiurolithiatic efficacy of Xanthium strumarium (L.) in ethylene glycol induced urolithiasis

Xanthium strumarium has traditionally been used in the treatment of urolitiasis especially by the rural people in India, but its antiurolithiatic efficacy was not explored scientifically till now. Therefore, the present study was designed to validate the ethnic practice scientifically, and explore the possible antiurolithiatic effect to rationalize its medicinal use. Urolitiasis was induced in hyperoxaluric rat model by giving 0.75% ethylene glycol (EG) for 28days along with 1% ammonium chloride (AC) for first 14days. Antiurolithiatic effect of aqueous-ethanol extract of Xanthium strumarium bur (xanthium) was evaluated based on urine and serum biochemistry, oxidative/nitrosative stress indices, histopathology, kidney calcium and calcium oxalate content and immunohistochemical expression of matrix glycoprotein, osteopontin (OPN). Administration of EG and AC resulted in hyperoxaluria, crystalluria, hypocalciuria, polyurea, raised serum urea, creatinine, erythrocytic lipid peroxidise and nitric oxide, kidney calcium content as well as crystal deposition in kidney section in lithiatic group rats. However, xanthium treatment significantly restored the impairment in above kidney function test as that of standard treatment, cystone. The up-regulation of OPN was also significantly decreased after xanthium treatment. The present findings demonstrate the curative efficacy of xanthium in ethylene glycol induced urolithiasis, possibly mediated through inhibition of various pathways involved in renal calcium oxalate formation, antioxidant property and down regulation of matrix glycoprotein, OPN. Therefore, future studies may be established to evaluate its efficacy and safety for clinical use.

An Explanation of the Underlying Mechanisms for the In Vitro and In Vivo Antiurolithic Activity of Glechoma longituba

Purpose. To use in vitro and in vivo models to evaluate Glechoma longituba extract to provide scientific evidence for this extract's antiurolithic activity. Materials and Methods. Potassium citrate was used as a positive control group. Oxidative stress (OS) markers and the expression of osteopontin (OPN) and kidney injury molecule-1 (KIM-1) were measured to assess the protective effects of Glechoma longituba. Multiple urolithiasis-related biochemical parameters were evaluated in urine and serum. Kidneys were harvested for histological examination and the assessment of crystal deposits. Results. In vitro and in vivo experiments demonstrated that treatment with Glechoma longituba extract significantly decreased calcium oxalate- (CaOx-) induced OPN expression, KIM-1 expression, and OS compared with the positive control group (P < 0.05). Additionally, in vivo rats that received Glechoma longituba extract exhibited significantly decreased CaOx deposits and pathological alterations (P < 0.05) compared with urolithic rats. Significantly lower levels of oxalate, creatinine, and urea and increased citrate levels were observed among rats that received Glechoma longituba (P < 0.05) compared with urolithic rats. Conclusion. Glechoma longituba has antiurolithic effects due to its possible combined effects of increasing antioxidant levels, decreasing urinary stone-forming constituents and urolithiasis-related protein expression, and elevating urinary citrate levels.

Translocation of mineralo-organic nanoparticles from blood to urine: a new mechanism for the formation of kidney stones?

Recent studies indicate that mineralo-organic nanoparticles form in various human body fluids, including blood and urine. These nanoparticles may form within renal tubules and increase in size in supersaturated urine, eventually leading to the formation of kidney stones. Here, we present observations suggesting that mineralo-organic nanoparticles found in blood may induce kidney stone formation via an alternative mechanism in which the particles translocate through endothelial and renal epithelial cells to reach urine. We propose that this alternative mechanism of kidney stone formation and the study of mineralo-organic nanoparticles in general may provide novel strategies for the early detection and treatment of ectopic calcifications and kidney stones.

Metabolomics analysis for hydroxy-L-proline-induced calcium oxalate nephrolithiasis in rats based on ultra-high performance liquid chromatography quadrupole time-of-flight mass spectrometry

About 80% of kidney stones are composed of calcium oxalate (CaOx) with variable amounts of calcium phosphate, and hyperoxaluria is considered as an important factor of CaOx nephrolithiasis. However, the underlying metabolic mechanisms of CaOx nephrolithiasis remain undefined. In this study, we successfully developed a rat model with hydroxy-L-proline (HLP) -induced CaOx nephrolithiasis. Rats were continuously orally administrated with HLP for 28 days. Urine and blood samples were collected from the rats treated with or without HLP at four different time points. UPLC-Q-TOF/MS was applied to profile the abundances of metabolites. To obtain more comprehensive analysis of metabolic profiling spectrum, combination of RP-LC and HILIC were applied. We identify 42 significant differential metabolites in the urine, and 13 significant differential metabolites in the blood. Pathway analysis revealed that the pathways involved in amino acid metabolism, taurine metabolism, bile acid synthesis, energy metabolism, TCA cycle, purine metabolism, vitamin metabolism, nicotinic acid and nicotinamide metabolism have been modulated by HLP treatment. This study suggested that a number of metabolic pathways are dysfunctional in the HLP induced crystal kidney injury, and further studies on those pathways are warranted to better understand the metabolic mechanism of CaOx nephrolithiasis.

Polyacrylic acid attenuates ethylene glycol induced hyperoxaluric damage and prevents crystal aggregation in vitro and in vivo

The study explores calcium oxalate crystal inhibiting characteristic of polyacrylic acid (pAA), an anionic polymer in in vitro and in vivo. Animals were divided into 5 groups where group 1 served as control, group 2 were made hyperoxaluric by supplementing with Ethylene glycol (EG) 0.75% (v/v) for 30 days. Group 3, 4 & 5 were also given with EG and treated simultaneously with 2.5, 5 & 10 mg of pAA/kg of body weight, respectively. Urine, serum and tissue analyses along with histological studies were performed at the end of the 30 days study. In vitro crystallization was significantly inhibited by pAA and further it was supported by particle size analyses, XRD and FT-IR studies. Toxicological analyses showed that pAA was safe to use in animals at concentrations below 100 mg/kg BW. In vivo anti-urolithic study showed significant improvement in urinary lithogenic factors (calcium, oxalate, phosphate, citrate & magnesium) and renal function parameters (creatinine, urea and protein). Tissue analyses on anti-oxidant enzyme activity and lipid peroxides showed maintenance of tissue antioxidant status in the pAA supplemented rats and histological studies demonstrated the nephroprotection offered by pAA and were concurrent to the biochemical analyses. Supplementation of pAA not only reduces the crystal aggregation but also regulates the expression and localization of crystal inhibiting proteins and gene expression of inflammatory cytokines in experimental animals. In summary, pAA is a potent anti-urolithic agent in rats and we can propose that 10 mg/kg body weight is the effective dosage of pAA and this concentration can be used for further studies.

Antiurolithiatic activity of Abelmoschus moschatus seed extracts against zinc disc implantation-induced urolithiasis in rats

Background:

The commonly used techniques for removing renal calculi are associated with the risk of acute renal injury and increase in stone recurrence which indicates an urgent need for alternate therapy.

Objectives:

The aim was to evaluate the antiurolithiatic activity of Abelmoschus moschatus seed extracts in rats.

Materials and Methods:

Urolithiasis was induced by surgical implantations of zinc disc in the urinary bladders of rats. Upon postsurgical recovery, different doses of chloroform (CAM) and methanolic (MAM) extracts of A. moschatus seeds (viz., 100, 200 and 400 mg/kg body weight) were administered to disc implanted rats for the period of 7 days by the oral route. Antiurolithiatic activity was evaluated by measuring various dimensions of stones and estimating levels of various biomarkers in serum and urine samples.

Results:

A significant decrease in urinary output was observed in disc implanted animals, which was prevented by the treatment with extracts. Supplementation with extracts caused significant improvement in glomerular filtration rate and urinary total protein excretion. The elevated levels of serum creatinine, uric acid, and blood urea nitrogen were also prevented by the extracts. The extracts significantly reduced deposition of calculi deposition around the implanted disc. This antiurolithiatic potential is observed at all doses (100, 200, and 400 mg/kg) of MAM, whereas only higher dose (400 mg/kg) of CAM showed significant antiurolithiatic potential.

Conclusion:

The extracts of A. moschatus seeds possessed significant antiurolithiatic activity. The possible mechanism underlying this effect is mediated collectively through diuretic, antioxidant, and free-radical scavenging effects of the plant.

Renal tubular injury induced by ischemia promotes the formation of calcium oxalate crystals in rats with hyperoxaluria

Hyperoxaluria and cell injury are key factors in urolithiasis. Oxalate metabolism may be altered by renal dysfunction and therefore, impact the deposition of calcium oxalate (CaOx) crystals. We investigated the relationship of renal function, oxalate metabolism and CaOx crystal deposition in renal ischemia. One hundred male Sprague-Dawley rats were randomly divided into four groups. Hyperoxaluria model (Group A and B) was established by feeding rats with 0.75 % ethylene glycol (EG). The left renal pedicle was clamped for 30 min to establish renal ischemia Groups (B and C), while Groups A and D underwent sham operation. Then, serum and urine oxalate (Ox), creatinine (Cr) and urea nitrogen (UN) levels were evaluated by liquid chromatography mass spectrometry (LCMS) and ion mass spectrum (IMS) at days 0, 2, 4, 7, and 14. CaOx crystallization was assessed by transmission electron microscope (TEM). A temporal and significant increase of serum Cr and UN levels was observed in Groups B and C compared to values obtained for Groups A and D (P < 0.05). Ox levels in serum and urine were significantly higher in Groups A and B than in the other two groups from day 7 (P < 0.05). In addition, CaOx crystallization was observed in both Groups A and B, but Group B showed earlier and more pronounced crystal deposition in the renal tissue. Our results indicated that renal tubular injury induced by renal ischemia might not affect Ox levels but could promote CaOx crystal retention under hyperoxaluria.

Oxalate-degrading microorganisms or oxalate-degrading enzymes: which is the future therapy for enzymatic dissolution of calcium-oxalate uroliths in recurrent stone disease?

Renal urolithiasis is a pathological condition common to a multitude of genetic, physiological and nutritional disorders, ranging from general hyperoxaluria to obesity. The concept of quickly dissolving renal uroliths via chemolysis, especially calcium-oxalate kidney stones, has long been a clinical goal, but yet to be achieved. Over the past 25 years, there has been a serious effort to examine the prospects of using plant and microbial oxalate-degrading enzymes known to catabolize oxalic acid and oxalate salts. While evidence is emerging that bacterial probiotics can reduce recurrent calcium-oxalate kidney stone disease by lowering systemic hyperoxaluria, the possible use of free oxalate-degrading enzyme therapy remains a challenge with several hurdles to overcome before reaching clinical practice.