Vitexin exerts protective effects against calcium oxalate crystal-induced kidney pyroptosis in vivo and in vitro.

BACKGROUND: Nephrolithiasis is a common urinary disease with a high recurrence rate of secondary stone formation. Several mechanisms are involved in the onset and recurrence of nephrolithiasis, e.g., oxidative stress, inflammation, apoptosis, and epithelial-mesenchymal transition (EMT). Vitexin, a flavonoid monomer derived from medicinal plants that exert many biological effects including anti-inflammatory and anticancer effects, has not been investigated in nephrolithiasis studies. Moreover, pyroptosis, a form of programmed cell death resulting from inflammasome-associated caspase activation, has not been studied in mice with nephrolithiasis. PURPOSE: We aimed to investigate the protective effect and underlying mechanisms of vitexin in nephrolithiasis, and the related role of pyroptosis in vivo and in vitro. METHODS: Mouse models of nephrolithiasis were established via intraperitoneal injection of glyoxylate, and cell models of tubular epithelial cells and macrophages were established using calcium oxalate monohydrate (COM). Crystal deposition and kidney tissue injury were evaluated by hematoxylin and eosin, and von Kossa staining. Renal oxidative stress indexes including malondialdehyde (MDA), superoxide dismutase (SOD), glutathione (GSH), and catalase (CAT), were analyzed. The renal expression of interleukin-1 beta (IL-1ß), gasdermin D (GSDMD), osteopontin (OPN), CD44, and monocyte chemotactic protein 1 (MCP-1), and EMT-related proteins in renal tubular epithelial cells was assessed. Cell viability and the apoptosis ratio were evaluated. RESULTS: In vivo, vitexin alleviated crystal deposition and kidney tissue injury, and decreased the level of MDA, and increased the levels of SOD, GSH, and CAT. Vitexin also reduced the levels of the pyroptosis-related proteins GSDMD, NLRP3, cleaved caspase-1, and mature IL-1ß, which were elevated in mice with nephrolithiasis, and repressed apoptosis and the expression of OPN and CD44. Moreover, vitexin mitigated F4/80-positive macrophage infiltration and MCP-1 expression in the kidneys. Furthermore, an in vitro study showed that vitexin increased the viability of HK-2 cells and THP-1-derived macrophages, which was impaired by treatment with COM crystals, decreased the medium lactate dehydrogenase (LDH) level, and inhibited the expression of pyroptosis-related proteins in HK-2 cells and macrophages. Vitexin repressed EMT of HK-2 cells, with increased expression of pan-cytokeratin (Pan-ck) and decreased expression of Vimentin and alpha-smooth muscle actin (α-SMA), and downregulated the Wnt/ß-catenin pathway. Moreover, vitexin suppressed tumor necrosis factor-α (TNF-α) and IL-1ß mRNA expression, which was upregulated by COM in macrophages. CONCLUSION: Vitexin exerts protective effects against nephrolithiasis by inhibiting pyroptosis activation, apoptosis, EMT, and macrophage infiltration. In addition, GSDMD-related pyroptosis mediates nephrolithiasis.

Kaempferol alleviates calcium oxalate crystal-induced renal injury and crystal deposition via regulation of the AR/NOX2 signaling pathway.

BACKGROUND: Calcium oxalate (CaOx) crystal deposition and crystal-induced renal tubular epithelial cell injury have been found to fundamentally contribute to the formation of CaOx nephrolithiasis. PURPOSE: In the current work, we aim to study the role and mechanism of kaempferol in CaOx crystal kidney deposition and crystal-induced renal injury. STUDY DESIGN: Mice models and HK-2 cells were used to investigate the effect of kaempferol in CaOx crystal-induced renal injury and crystal deposition in the kidney and its underlying mechanism by a series of experiments. METHODS: CaOx crystal deposition in mice renal tubulars and tubular damage were evaluated. And crystal adhesion to HK-2 cells, as well as cellular injury were identified. Furthermore, the effect of kaempferol on the expression of androgen receptor (AR) in renal tubular epithelial cells was assessed. The interaction between AR and nicotinamide adenine dinucleotide phosphate oxidase 2 (NOX2), and the intrinsic molecular mechanism of how AR regulated NOX2 in HK-2 cells were dissected. Additionally, several different assays were applied to analyze the expression levels of various related genes in this study. RESULTS: It was revealed that kaempferol reduced CaOx crystal deposition in renal tubulars and crystal adhesion to HK-2 cells. Meanwhile, the results of in vivo and in vitro experiments corroborated that crystal-associated cellular injury, oxidative stress, inflammation and over-expression of OPN and CD44 in the kidney were ameliorated by kaempferol. Moreover, kaempferol functioned on inhibiting the expression of AR in renal tubular epithelial cells, and AR was able to up-regulate the expression of NOX2 at the transcriptional level by directly binding to the promoter of NOX2. Kaempferol decreased crystal deposition and crystal-induced renal oxidative and inflammatory injury by the down-regulation of AR/NOX2 signaling pathway. CONCLUSION: Taken together, our study findings suggest that kaempferol has a suppressive effect on renal AR expression, which can attenuate CaOx crystal deposition and crystal-induced kidney injury through repressing oxidative stress and inflammation in the kidney by modulating the AR/NOX2 signaling pathway. It demonstrates that kaempferol may have preventive and therapeutic potential for CaOx nephrolithiasis.

Theaflavin protects against oxalate calcium-induced kidney oxidative stress injury via upregulation of SIRT1.

Renal tubular cell injury induced by calcium oxalate (CaOx) is a critical initial stage of kidney stone formation. Theaflavin (TF) has been known for its strong antioxidative capacity; however, the effect and molecular mechanism of TF against oxidative stress and injury caused by CaOx crystal exposure in kidneys remains unknown. To explore the potential function of TF on renal crystal deposition and its underlying mechanisms, experiments were conducted using a CaOx nephrocalcinosis mouse model established by glyoxylate intraperitoneal injection, and HK-2 cells were subjected to calcium oxalate monohydrate (COM) crystals, with or without the treatment of TF. We discovered that TF treatment remarkably protected against CaOx-induced kidney oxidative stress injury and reduced crystal deposition. Additionally, miR-128-3p expression was decreased and negatively correlated with SIRT1 level in mouse CaOx nephrocalcinosis model following TF treatment. Moreover, TF suppressed miR-128-3p expression and further abolished its inhibition on SIRT1 to attenuate oxidative stress in vitro. Mechanistically, TF interacted with miR-128-3p and suppressed its expression. In addition, miR-128-3p inhibited SIRT1 expression by directly binding its 3'-untranslated region (UTR). Furthermore, miR-128-3p activation partially reversed the acceerative effect of TF on SIRT1 expression. Taken together, TF exhibits a strong nephroprotective ability to suppress CaOx-induced kidney damage through the recovery of the antioxidant defense system regulated by miR-128-3p/SIRT1 axis. These findings provide novel insights for the prevention and treatment of renal calculus.

Nephroprotective and antilithiatic activities of Costus spicatus (Jacq.) Sw.: Ethnopharmacological investigation of a species from the Dourados region, Mato Grosso do Sul State, Brazil.

ETHNOPHARMACOLOGICAL RELEVANCE: Costus spicatus (Jacq.) Sw., also known as "cana-do-brejo," is a species that is widely used in Brazilian traditional medicine for the treatment of kidney diseases. However, no studies have evaluated its nephroprotective and antilithiatic effects. AIM: To investigate nephroprotective and antilithiatic effects of C. spicatus in a preclinical model of acute kidney injury (AKI) and in vitro nephrolithiasis. MATERIALS AND METHODS: C. spicatus leaves were collected directly from the natural environment in the Dourados region, Mato Grosso do Sul State, Brazil. The ethanol-soluble fraction of C. spicatus (ESCS) was obtained by infusion. Phytochemical characterization was performed by liquid chromatography coupled to diode array detector and mass spectrometer (LC-DAD-MS). We assessed whether ESCS has acute or prolonged diuretic activity. The nephroprotective effects of ESCS were evaluated in a model of AKI that was induced by glycerol (10 ml/kg, intramuscularly) in Wistar rats. Different doses of ESCS (30, 100, and 300 mg/kg) were administered orally for 5 days before the induction of AKI. Urinary parameters were measured on days 1, 3, 5, and 7. Twenty-four hours after the last urine collection, blood samples were obtained for the biochemical analysis. Blood pressure levels, renal vascular reactivity, renal tissue redox status, and histopathological changes were measured. Antilithiatic effects were evaluated by in vitro crystallization. Calcium oxalate precipitation was induced by sodium oxalate in urine samples with ESCS at 0.05, 0.5, and 5 mg/ml. RESULTS: From LC-DAD-MS analyses, flavonoids, saponins and other phenolic compounds were determined in the composition of ESCS. Significant reductions of the excretion of urinary total protein, creatinine, sodium, and potassium were observed in the AKI group, with significant histopathological damage (swelling, vacuolization, necrosis, and inflammatory infiltration) in the proximal convoluted tubule. Treatment with ESCS exerted a significant nephroprotective effect by increasing the urinary excretion of total protein, urea, creatinine, sodium, potassium, calcium, and chloride. All of the groups that were treated with ESCS exhibited a reduction of histopathological lesions and significant modulation of the tissue redox state. We also observed a concentration-dependent effect of ESCS on the crystallization of urinary crystals, with reductions of the size and proportion of monohydrated crystals. CONCLUSION: The data suggest that C. spicatus has nephroprotective and antilithiatic effects, suggesting possible effectiveness in its traditional use.

Fu-Fang-Jin-Qian-Cao herbal granules protect against the calcium oxalate-induced renal EMT by inhibiting the TGF-ß/smad pathway.

CONTEXT: Nephrolithiasis is a major public health problem worldwide and Fu-Fang-Jin-Qian-Cao granules (FFJQC) is a traditional Chinese herbal formula that is used to treat nephrolithiasis. The main component of nephrolithiasis is calcium oxalate (CaOx) and the epithelial-mesenchymal transition (EMT) shown to play a crucial role in CaOx-induced kidney injury. However, the mechanism underlying the therapeutic effect of FFJQC on the CaOx-induced renal EMT is unknown. OBJECTIVE: This study explores the therapeutic benefits and mechanism of FFJQC in oxalate-induced kidney injury. MATERIALS AND METHODS: 60 male C57BL/6 mice were used in this experiment and divided into 6 groups. A mouse kidney stone model was created by intraperitoneal injection of glyoxylate at a dose of 100 mg/kg for 6 days. The standardized FFJQC was used to treat mouse crystal kidney injury by gavage at 1.35 and 2.7 g/kg, respectively. Western blotting and immunostaining for E-cadherin, cytokeratin 18 (CK18), vimentin, smooth muscle α-actin (α-SMA) and transforming growth factor ß (TGF-ß)/Smad pathway were conducted on renal tissues. RESULTS: Following CaOx-induced kidney injury, the levels of E-cadherin and CK18 in kidney decreased, while vimentin and α-SMA levels increased. The FFJQC treatment increased the levels of E-cadherin and CK18 and decreased vimentin and α-SMA levels in varying degrees. What's more, the FFJQC reduced the expression of CaOx-induced fibrosis marker collagen II. CONCLUSION: FFJQC alleviated the CaOx-induced renal EMT and fibrosis by regulating TGF-ß/smad pathway. Therefore, the FFJQC is an important traditional Chinese medicine for the treatment of CaOx-induced renal injury and fibrosis.

Dietary and lifestyle factors for primary prevention of nephrolithiasis: a systematic review and meta-analysis.

BACKGROUND: Dietary and lifestyle factors may play an important role in the increasing prevalence of nephrolithiasis. We aimed to review and quantify the associations between lifestyle factors and incident nephrolithiasis and suggest lifestyle changes for the primary prevention of nephrolithiasis. METHODS: PubMed, EMBASE, and Cochrane Library were searched up to May 2019, for observational studies and randomized controlled trials (RCTs) that assessed modifiable lifestyle factors and risk of nephrolithiasis in adults. Pooled relative risks (RRs) and 95% confidence intervals (CIs) were computed using a random effects model. The I2 statistic was employed to evaluate heterogeneity. Subgroup analysis, sensitivity analysis and meta-regression were also conducted whenever possible. RESULTS: Fifty relevant articles with 1,322,133 participants and 21,030 cases in total were identified. Prominent risk factors for incident stones were body mass index (1.39,1.27-1.52), dietary sodium (1.38, 1.21-1.56), fructose, meat, animal protein, and soda. In contrast, protective factors included fluid intake (0.55, 0.51-0.60), a Dietary Approaches to Stop Hypertension (DASH) style diet (0.69, 0.64-0.75), alcohol (0.69, 0.56-0.85), water, coffee, tea, vegetables, fruits, dietary fiber, dietary calcium (0.83, 0.76-0.90), and potassium. Vitamin D (1.22, 1.01-1.49) and calcium (1.16, 1.00-1.35) supplementation alone increased the risk of stones in meta-analyses of observational studies, but not in RCTs, where the cosupplementation conferred significant risk. CONCLUSIONS: Several modifiable factors, notably fluid intake, dietary patterns, and obesity, were significantly associated with nephrolithiasis. Long-term RCTs are required to investigate the cost-effectiveness of dietary patterns for stone prevention. The independent and combined effects of vitamin D and calcium supplementation on nephrolithiasis need further elucidation.

MOnitored supplementation of VItamin D in preterm infants (MOSVID trial): study protocol for a randomised controlled trial.

BACKGROUND: The pivotal role of vitamin D (vit D) in skeletal health is well known. Neonatal vit D storage at birth is dependent on maternal levels, and newborns receive 50-70% of their mother's 25-hydroxyvitamin D [25(OH)D]. Deficiency of vit D can lead to prematurity bone disease, with an incidence of up to 55% in infants weighing < 1000 g. The aim of this study is to assess the effectiveness of monitored supplementation of vit D in a population of preterm infants. METHODS/DESIGN: Preterm infants born at 24-32 weeks of gestation will be recruited within the first 7 days of life. Depending on the type of feeding, and after reaching partial enteral feeding or at 7 days of life, vit D supplementation will consist of 500 IU and an additional 150-300 IU/kg included in human milk fortifiers (if fed exclusively with breast milk) or 190 IU/kg in milk formulas. Subjects will be randomised to either monitored (with an option of dose modification based on 25(OH)D levels as per protocol) or standard therapy up to 52 weeks of post-conceptional age (PCA). The primary outcome measure will be the number of neonates with deficiency or excess levels of 25(OH)D at 40 ±2 weeks of PCA. Additional 25(OH)D levels will be measured at birth, at 4 and 8 weeks of age, and/or at 35 and 52 ±2 weeks of PCA. Secondary objectives will include the incidence of osteopenia, nephrocalcinosis and nephrolithiasis. Serum parameters of calcium phosphorus metabolism will also be measured. DISCUSSION: Despite multiple years of research and numerous publications, there is still a lack of consensus in regard to how much vit D infants should receive and how long they should receive it. Because 80% of calcium and phosphorus placental transfer occurs between 24 and 40 weeks of gestation, preterm infants are especially prone to adverse effects of vit D insufficiency. However, both inadequate and excessive amounts of vit D may be unsafe and lead to serious health issues. The results of our study may shed new light on these concerns and contribute to optimising vit D supplementation. TRIAL REGISTRATION: ClinicalTrials.gov, NCT03087149 . Registered on 15 March 2017.

Role of gut microbiota against calcium oxalate.

Nephrolithiasis is a condition marked by the presence or formation of stones in kidneys. Several factors contribute to kidney stones development such as environmental conditions, type of dietary intake, gender and gastrointestinal flora. Most of the kidney stones are composed of calcium phosphate and calcium oxalate, which enter in to the body through diet. Both sources of oxalates become dangerous when normal flora of gastrointestinal tract is disturbed. Oxalobacter and Lactobacillus species exist symbiotically in the human gut and prevent stone formation by altering some biochemical pathways through production of specific enzymes which help in the degradation of oxalate salts. Both Oxalobacter and Lactobacillus have potential probiotic characteristics for the prevention of kidney stone formation and this avenue should be further explored.

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.

Effect of potassium citrate supplement on stone recurrence before or after lithotripsy: systematic review and meta-analysis.

This meta-analysis summarizes the available evidence on the effectiveness of citrate supplement for preventing the recurrence of nephrolithiasis in patients undergoing extracorporeal shock wave lithotripsy (SWL). Electronic searches were conducted using Medline-PubMed, Web of Science, Embase, BVS (Scielo, Lilacs), and Google Scholar literature databases. The authors worked in pairs to select studies that met the following criteria: randomized controlled trials that were conducted in adults and assessed the effect of potassium citrate supplement before or after SWL therapy for urolithiasis. Our primary aim was to asses the stone-free rate among the groups included in the studies. Fixed effect was used in the meta-analysis with 95% confidence interval (95% CI). Heterogeneity was analyzed by the I 2 value. A total of 2505 references were initially selected. Of those, four were subjected to meta-analysis contributing five samples. These four studies included 374 participants who were followed for a period of 12 months after SWL. Mean potassium citrate dosage was approximately 55 mEq/day (18 mmol). The results showed that citrate supplement significantly protected against the recurrence of nephrolithiasis during 1 year after SWL [RR; 95% CI 0.21 (0.13, 0.31)]. The heterogeneity was not significant across the analyzed studies (p = 0.224). The quality of the analyzed studies was generally low. The available evidence shows that citrate supplement effectively reduces the recurrence of nephrolithiasis in patients undergoing SWL. However, statistical analysis of a larger trial conducted with methodological rigor is warranted.

Metabolic diagnosis and medical prevention of calcium nephrolithiasis and its systemic manifestations: a consensus statement.

BACKGROUND: Recently published guidelines on the medical management of renal stone disease did not address relevant topics in the field of idiopathic calcium nephrolithiasis, which are important also for clinical research. DESIGN: A steering committee identified 27 questions, which were proposed to a faculty of 44 experts in nephrolithiasis and allied fields. A systematic review of the literature was conducted and 5216 potentially relevant articles were selected; from these, 407 articles were deemed to provide useful scientific information. The Faculty, divided into working groups, analysed the relevant literature. Preliminary statements developed by each group were exhaustively discussed in plenary sessions and approved. RESULTS: Statements were developed to inform clinicians on the identification of secondary forms of calcium nephrolithiasis and systemic complications; on the definition of idiopathic calcium nephrolithiasis; on the use of urinary tests of crystallization and of surgical observations during stone treatment in the management of these patients; on the identification of patients warranting preventive measures; on the role of fluid and nutritional measures and of drugs to prevent recurrent episodes of stones; and finally, on the cooperation between the urologist and nephrologist in the renal stone patients. CONCLUSIONS: This document has addressed idiopathic calcium nephrolithiasis from the perspective of a disease that can associate with systemic disorders, emphasizing the interplay needed between urologists and nephrologists. It is complementary to the American Urological Association and European Association of Urology guidelines. Future areas for research are identified.

Do teas rich in antioxidants reduce the physicochemical and peroxidative risk factors for calcium oxalate nephrolithiasis in humans? Pilot studies with Rooibos herbal tea and Japanese green tea.

Several experimental and animal studies have demonstrated that substances rich in antioxidants can reduce the physicochemical and peroxidative risk factors for calcium oxalate (CaOx) renal stone formation in urine and blood. However, there are very few such investigations in humans. In the present pilot study, two varieties of tea, a green one from Japan (JGT) and a herbal one from South Africa (Rooibos) (RT), both rich in antioxidants, were administered to a group of CaOx stone formers (SF) (n = 8) for 30 days. Both teas were analysed for polyphenols by high-performance liquid chromatography and for minerals by plasma atomic and optical emission spectroscopy. 24 h urines (baseline and day 30) were analysed for lithogenic factors. CaOx metastable limits and crystal nucleation and growth kinetics were also determined in each urine sample. Deposited crystals were inspected by scanning electron microscopy. Blood samples were collected (baseline and day 30). Biomarkers of oxidative stress including plasma and urinary thiobarbituric acid reactive substances (TBARS) and urinary N-acetyl-ß-D-glucosaminidase (NAG) were also determined. Urinary physicochemical risk factors were also investigated after ingestion of RT for 30 days in two control groups (CG1 and CG2), the latter one of which consisted of habitual JGT drinkers. Statistical analyses were performed using Wilcoxon signed rank tests and Mann-Whitney tests for paired and independent measurements, respectively. Several flavonoids and catechins were quantified in RT and JGT, respectively, confirming that both teas are rich sources of antioxidants. Mineral content was found to be far below dietary reference intakes. There were no significant changes in any of the urinary physicochemical or peroxidative risk factors in the control groups or in SF, except for the supersaturation (SS) of brushite (Bru) which decreased in the latter group after ingestion of JGT. Crystal morphology showed a tendency to change from mixed CaOx mono- and di-hydrate to monohydrate after ingestion of each tea. Since the latter form has a stronger binding affinity for epithelial cells, this effect is not protective. Analysis of the physicochemical and peroxidative risk factors in CG1 and CG2 did not reveal any evidence of a synergistic effect between the two teas. Paradoxically, baseline risk factors in the habitual JGT control group were significantly raised relative to those in CG1. Our preliminary results suggest that ingestion of RT and JGT does not reduce the risk factors for CaOx stone formation in humans, but these findings need to be tested in further studies involving much larger sample sizes.

[Antiurolithiasic effect of a plant mixture of Herniaria glabra, Agropyron repens, Equisetum arvense and Sambucus nigra (Herbensurina®) in the prevention of experimentally induced nephrolithiasis in rats]. / EFECTO ANTIUROLITIÁSICO DE UNA FORMULACIÓN DE LAS PLANTAS HERNIARA GLABRA, AGROPYRON REPENS, EQUISETUM ARVENSE, Y SAMBUCUS NIGRA (HERBENSURINA®) EN UN MODELO EXPERIMENTAL DE NEFROLITIASIS EN RATAS.

OBJECTIVE: To determine the effect of a botanical formulation of Herniaria glabra, Agropyron repens, Equisetum arvense, and Sambucus nigra as a preventive agent in an experimentally induced nefrolithiasis model in rats. METHODS: Six groups of six Wistar male rats each were induced for nefrolithiasis by treatment with 0.75% ethylene glycol (EG) and 1% ammonium chloride for three days and then EG only for 15 days. One group was treated with placebo (control group) and the other groups (treated groups) were treated with 30 mg/Kg, 60 mg/Kg, 125 mg/Kg, 250 mg/Kg and 500 mg/Kg of the plant extract formulation (PEF). 24-h urine and water samples were collected one day before EG administration and at 7, 13 and 18 days to determine diuresis, crystalluria and urine biochemistry. The kidneys were removed for histological analysis. The phytochemical characterization of PEF and each of its component plant extracts was performed using gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry. RESULTS: Animals treated with 125 mg/Kg of the PEF had statistically significantly lower calcium oxalate crystals deposits content compared to the control group. All PEF doses statistically significantly decreased the number of microcalcifications compared to the control group. Furthermore, the number of kidneys affected by subcapsular fibrosis was statistically significantly higher in control group than in treated groups with the PEF. The diuresis of the 125 mg/Kg and 500 mg/Kg PEF-treated groups was statistically significantly higher than that of the control group. A phytochemical analysis demonstrated the presence of flavonoids, dicarboxylic acids and saponins. CONCLUSION: Treatment with PEF prevents deposits of calcium oxalate crystals formation and of microcalcifications in the kidney, and reduces the risk of fibrosis subcapsular. 125 mg/Kg of PEF is the dose that has a greater effect on the studied parameters.

Effect of mitochondrial potassium channel on the renal protection mediated by sodium thiosulfate against ethylene glycol induced nephrolithiasis in rat model

Purpose: Sodium thiosulfate (STS) is clinically reported to be a promising drug in preventing nephrolithiasis. However, its mechanism of action remains unclear. In the present study, we investigated the role of mitochondrial KATP channel in the renal protection mediated by STS. Materials and Methods: Nephrolithiasis was induced in Wistar rats by administrating 0.4% ethylene glycol (EG) along with 1% ammonium chloride for one week in drinking water followed by only 0.75% EG for two weeks. Treatment groups received STS, mitochondrial KATP channel opener and closer exclusively or in combination with STS for two weeks. Results: Animals treated with STS showed normal renal tissue architecture, supported by near normal serum creatinine, urea and ALP activity. Diazoxide (mitochondria KATP channel opening) treatment to the animal also showed normal renal tissue histology and improved serum chemistry. However, an opposite result was shown by glibenclamide (mitochondria KATP channel closer) treated rats. STS administered along with diazoxide negated the renal protection rendered by diazoxide alone, while it imparted protection to the glibenclamide treated rats, formulating a mitochondria modulated STS action. Conclusion: The present study confirmed that STS render renal protection not only through chelation and antioxidant effect but also by modulating the mitochondrial KATP channel for preventing urolithiasis.

Prevention and treatment of nephrolithiasis: a review on the role of spa therapy.

The prevalence and incidence of nephrolithiasis is reported to be increasing across the world. It is a disease of increased urinary concentration of stone-forming salts. The physicochemical mechanism of stone formation includes precipitation, homogenous/heterogeneous nucleation, growth, aggregation and concretion of various modulators in urine. Necessary condition to develop stones is urinary supersaturation, due to reduced urinary volume or to an excesses solutes. Fluid intake is the main determinant of urine volume. Urine dilution can significantly decrease both the crystallization rate of the urinary salts and the aggregation of the crystals. A correct fluid intake can act on different effects: urinary tract washing, urinary volume increasing and dilution of solutes. In addition mineral waters have other particular features: greater diuretic effect, more important urinary dilution with solutes and microbial concentration reduction, urinary pH changes, superior washout effect due to mechanical effects and ureteral contractions. Adequate water intake is the most important conservative strategy in urolithiasis prevention; particularly hydropinotherapy with oligomineral water should be considered as an important instrument to prevent stones in subjects predisposed to the disease (family members of people suffering from kidney stones), to reduce relapses, and can help to eliminate residual fragments also after extracorporeal shock wave lithotripsy. It is recommended a management with increased mineral water intake to promote urine volume of at least 2.5L each day to prevent stone formation. Obviously water intake shall be varied in relation to the presence of contraindications or any diseases.

Inhalation of hydrogen gas ameliorates glyoxylate-induced calcium oxalate deposition and renal oxidative stress in mice.

The aim of this study is to evaluate the protective effect and underlying mechanism of hydrogen gas (H2) to glyoxylate induced renal calcium oxalate (CaOx) crystal deposition in mice. In present work, rodent renal CaOx crystal deposition model was introduced by intra-abdominal injection of glyoxylate (100 mg/kg/d) for 5 days. Two days before administration of glyoxylate, inhalation of H2 for 30 min per day was initiated and continued for 7 days. By the end of the study, the samples of 24 hours urine, serum and renal tissue were collected for biochemical and pathological assay. According to levels of urine calcium excretion, renal calcium deposition, a serum excretion of kidney injury molecule-1 (KIM-1) assay and a TUNEL assay, inhalation of H2 could successfully decrease the CaOx crystallizations and protect against renal injury. Crystal deposition in the kidneys is associated with oxidative stress, which was indicated by increased levels of renal malondialdehyde (MDA) and 8-hydroxydeoxyguanosine (8-OHdG) and decreased activities of superoxide dismutase (SOD), glutathione (GSH) and catalase (CAT). These effects were reversed by a high-dose H2 pretreatment. The renal expressions of osteopontin (OPN), CD44, monocyte chemoattractant protein-1 (MCP-1) and interleukin-10 (IL-10) were markedly increased in glyoxylate-treated mice, and H2 significantly attenuated the increase of OPN, CD44 and MCP-1 but upregulated the expression of IL-10. Our findings demonstrate that inhalation of H2 reduces renal crystallization, renal oxidative injury and inflammation and it may be a candidate agent with few adverse effects for prevention of nephrolithiasis.

Preventive treatment of calcium oxalate crystal deposition with immortal flowers.

ETHNOPHARMACOLOGICAL RELEVANCE: A number of medicinal plants are used for their diuretic, urolithiatic and anti-inflammatory effects on urinary system problems in Turkey and the most common traditional remedy for kidney stones is the tea of immortal flowers. The aim of this study is to evaluate the preventive effect of infusions prepared from capitulums of Helichrysum graveolens (M.Bieb.) Sweet (HG) and Helichrysum stoechas ssp. barellieri (Ten.) Nyman (HS) on formation of kidney stones. MATERIALS AND METHOD: Sodium oxalate (Ox-70mg/kg intraperitoneally) was used to induce kidney stones on Wistar albino rats. At the same time, two different doses of the plant extracts (HG: 62.5 and 125mg/kg; HS: 78 and 156mg/kg) were dissolved in the drinking water and administered to animals for 5 days. Potassium citrate was used as positive control in the experiments. During the experiment, water intake, urine volume and body weights of the animals were recorded. At the end of the experiments, liver, kidney and body weights of the animals were determined; biochemical analysis were conducted on urine, blood and plasma samples. Histopathological changes in kidney tissues were examined and statistical analysis were evaluated. RESULTS: HS extract showed the highest preventive effect at 156mg/kg dose (stone formation score: 1.16), whereas a number of kidney stones were maximum in sodium oxalate group (stone formation score: 2.66). Helichrysum extracts decreased urine oxalate and uric acid levels and increased citrate levels significantly. In addition, Helichrysum extracts regulated the negative changes in biochemical and hematological parameters occurred after Ox injection. CONCLUSIONS: We conclude that Helichrysum extracts could reduce the formation and growth of kidney stones in Ox-induced urolithiasis and can be beneficial for patients with recurrent stones. In addition, this is the first study on the preventive effect of immortal flowers.

In vitro anti-lithogenic activity of lime powder regimen (LPR) and the effect of LPR on urinary risk factors for kidney stone formation in healthy volunteers.

Hypocitraturia, hypokaliuria, and increased oxidative stress are common lithogenic risk factors found in nephrolithiasis patients, especially in Thailand. We previously developed lime powder regimen (LPR), and demonstrated that LPR delivered citraturic, alkalinizing, and antioxidative effects in kidney stone patients. In this study, in vitro anti-lithogenic activity, in vivo acute toxicity, and crossover-designed phase 1 trial (in 13 healthy volunteers) of LPR were investigated. LPR inhibited the growth of calcium oxalate monohydrate (COM) crystals in dose-dependent manner, and inhibited the intracellular production of reactive oxygen species (ROS) in COM-treated HK-2 cells. LPR did not significantly alter viability of HK-2 cells. No acute toxicity was detected in mice orally fed with LPR (10 g/kg). No adverse effect and complaint of LPR ingestion (5 g/dose) were observed in the tested volunteers. Plasma citrate was elevated at 30 min after LPR load, which was higher than the water load control. Plasma potassium was significantly elevated at 30 min after LPR load and remained high for 2 h, and at 2 h, it was significantly higher than the water load. Urinary citrate was significantly increased at 1 h after LPR load and remained high for 2 h, and at 2 h, it was significantly higher than the water load. Urinary potassium was significantly increased at 1 h after LPR load and remained high for 3 h, and its levels at 1, 2, and 3 h were significantly higher than the water load. Urinary total antioxidant status was significantly increased at 2 h after LPR load. In conclusion, LPR had an inhibitory effect on COM growth and exerted as antioxidant to attenuate ROS production in the COM-treated renal tubular cells. LPR provided citraturic, kaliuric, and antioxidative responses in healthy individuals without any adverse events. This suggests that LPR is well tolerated and safe for daily consumption.

Antilithiatic effects of crocin on ethylene glycol-induced lithiasis in rats.

In this study, the antilithiatic potential of crocin, a pharmacologically active constituent of Crocus sativus L. (saffron), was evaluated against ethylene glycol (EG)-induced nephrolithiasis in rats. Negative control rats were provided with EG (1 %) in drinking water for 30 days. crocin (10, 20 and 40 mg/kg, i.p.) was administered simultaneously once daily for 30 days (prophylactic regimen) or 14 days after stone induction (therapeutic study). For biochemical analysis, 24-h urine was collected from all experimental animals at the beginning (day 0) and end of the experiment (day 30). The urine output was evaluated during the first 24 h (day 1). Ethylene glycol feeding resulted in decreased hyperoxaluria (P < 0.01) and total protein loss (P < 0.001), along with decreased excretion of citrate and magnesium (P < 0.01) compared with the intact animals. Treatment with prophylactic regimen of crocin (20 and 40 mg/kg) significantly reduced the elevated oxalate, and increased the citrate and magnesium levels of urine. The attenuation of protein loss was only seen with a high dose of crocin in a prophylactic study. Urine volume was not significantly altered after EG or crocin administration. The increased number of calcium deposits in the kidney tissue of lithiatic rats was decreased after prophylactic treatment with 20 and 40 mg/kg of crocin. The urinary ionic parameters and crystal count were not significantly altered after the therapeutic study. A marked increase in malondialdehyde (MDA, a lipid peroxidation product) level was observed in the EG-given group. Treatment with crocin (20 and 40 mg/kg) reduced the elevated levels of MDA. Results indicate that crocin can be effective in preventing urine calculi formation and recurrence of the disease. The mechanism underlying this effect is mediated possibly through balancing promoter and inhibitor factors and an antioxidant effect.

Oxidative stress and nephrolithiasis: a comparative pilot study evaluating the effect of pomegranate extract on stone risk factors and elevated oxidative stress levels of recurrent stone formers and controls.

Previous studies have linked oxidative stress and nephrolithiasis. Animal studies have demonstrated that pomegranate juice may play a role in preventing stone formation. We examined differences between recurrent stone formers (RSFs) and non-stone formers (NSFs) regarding oxidative stress and the effect of pomegranate administration on risk factors for nephrolithiasis. RSFs were recruited prospectively and matched to a group of NSFs. Subjects submitted urine and blood samples prior to and after receiving pomegranate polyphenol extract (1,000 mg) for 90 days. Serum and urine samples were analyzed for stone risk and oxidative stress. Thirty subjects completed the study. RSFs had significantly higher levels of oxidative stress at baseline as measured by urinary 8-hydroxy-deoxyguanosine (p < 0.0001), 2.2'-azobis (2-amidinopropane) hydrochloride-induced serum lipid peroxidation [increased levels of lipid peroxides (p = 0.0002), and thiobarbituric acid reactive substances (p = 0.002)], but not by serum paraoxonase1 (PON1) arylesterase activity (p > 0.99), or by highly sensitive C-reactive protein (p > 0.99). Following pomegranate supplementation, there was a 10 % increase in PON1 activity in RSFs (p = 0.007), which correlated with a trend toward decreasing values of supersaturation of calcium oxalate (SSCaOx; p = 0.05). RSFs have markedly higher levels of oxidative stress than NSFs. While the ability to prevent stone formation through supplementation cannot be determined in this pilot study, supplementation with pomegranate extract does not increase the risk of stones and may confer some benefit in lowering SSCaOX in those patients with increased PON-1 levels following supplementation, confirming findings of previous animal models.