Calcium Oxalate Stone Research Articles

Bidirectional Impact of Varying Severity of Acute Kidney Injury on Calcium Oxalate Stone Formation.

Acute Kidney Injury (AKI) is a prevalent renal disorder. The occurrence of AKI may promote the formation of renal calcium oxalate stones by exerting continuous effects on renal tubular epithelial cells. We aimed to delineate the molecular interplay between AKI and nephrolithiasis. A mild (20 min) and severe (30 min) renal ischemia-reperfusion injury model was established in mice. Seven days after injury, calcium oxalate stones were induced using glyoxylate (Gly) to evaluate the impact of AKI on the formation of kidney stones. Transcriptome sequencing was performed on tubular epithelial cells (TECs) to elucidate the relationship between AKI severity and kidney stones. Key transcription factors (TF) regulating differential gene transcription levels were identified using motif analysis, and pioglitazone, ginkgetin, and fludarabine were used for targeted therapy to validate key transcription factors as potential targets for kidney stone treatment. Severe AKI led to increased deposition of calcium oxalate crystals in renal, impaired kidney function, and upregulation of kidney stone-related gene expression. In contrast, mild AKI was associated with decreased crystal deposition, preserved kidney function, and downregulation of similar gene expression. Transcriptomic analysis revealed that genes associated with inflammation and cell adhesion pathways were significantly upregulated after severe AKI, while genes related to energy metabolism pathways were significantly upregulated after mild AKI. An integrative bioinformatic analysis uncovered a TF regulatory network within TECs, pinpointing that PKNOX1 was involved in the upregulation of inflammation-related genes after severe AKI, and inhibiting PKNOX1 function with Pioglitazone could simultaneously reduce the increase of calcium oxalate crystals after severe AKI in kidney. On the other hand, motif analysis also revealed the protective role of STAT1 in the kidneys after mild AKI, enhancing the function of STAT1 with Ginkgetin could reduce kidney stone formation, while the specific inhibitor of STAT1, Fludarabine, could eliminate the therapeutic effects of mild AKI on kidney stones. Inadequate repair of tubular epithelial cells after severe AKI increases the risk of kidney stone formation, with the upregulation of inflammation-related genes regulated by PKNOX1 playing a role in this process. Inhibiting PKNOX1 function can reduce kidney stone formation. Conversely, after mild AKI, effective cell repair through upregulation of STAT1 expression can protect TEC function, reduce stone formation, and activating STAT1 function can also achieve the goal of treating kidney stones.

Pharmacotherapy for patients with calcium oxalate stones and abnormal urine chemistry: A systematic review and meta-analysis for the Japanese Clinical Practice Guidelines for the Management of Urinary Stones, Third Edition.

We performed a systematic review and meta-analysis to evaluate the benefits and harms of pharmacotherapies for patients with calcium oxalate stones and abnormal urine chemistry. This article is a modified and detailed version of the commentary on Clinical Question 10 described in the Japanese Clinical Practice Guidelines for the Management of Urinary Stones, Third Edition. PubMed and Ichushi Web were searched through August 2020 for articles on pharmacotherapies for calcium oxalate stones (thiazides, citrate preparations, uric acid production inhibitors, and magnesium preparations). Two reviewers independently selected randomized controlled trials reporting reduction of stone recurrence and adverse drug reactions as outcomes and performed data extraction and quality assessment. Meta-analyses with random effects models and rating of the strength of evidence were performed. Pharmacotherapies were shown to significantly reduce stone recurrence (risk ratio 0.47, 95% confidence interval 0.35-0.63). Meanwhile, the pharmacotherapies increased adverse drug reactions leading to study dropout (risk ratio 2.51, 95% confidence interval 1.09-5.75) and adverse drug reactions/adverse events (risk ratio 1.95, 95% confidence interval 1.07-3.56). The reported adverse drug reactions were, however, mainly minor and did not frequently require discontinuation of medication (2%-16%). The strengths of evidence for both outcomes were rated as moderate, because the risk of bias, indirectness, inconsistency, imprecision, and publication bias were all serious except for one item. The overall strength of evidence across outcomes was therefore determined to be moderate. These results support the conditional recommendation to initiate pharmacotherapies for patients with calcium oxalate stones and abnormal urine chemistry.

Optimizing antigen preparation for oxalyl-CoA decarboxylase enzyme diagnostic kit and ELISA system cutoff determination.

The prevalence of kidney stone disease is increasing globally, with calcium oxalate stones being the most common type. Oxalyl-CoA decarboxylase (OXC), an enzyme produced by the gut bacterium Oxalobacter formigenes, plays a crucial role in oxalate metabolism. Deficiencies in OXC activity can lead to the accumulation of oxalate, contributing to kidney stone formation. This study aimed to develop a reliable diagnostic assay for OXC by optimizing antigen production and establishing a cutoff value for an enzyme-linked immunosorbent assay (ELISA). We cloned, expressed, and purified recombinant OXC protein in Escherichia coli BL21(DE3), and generated specific polyclonal antibodies in rabbits. The ELISA system was optimized and validated using serum samples from 40 healthy individuals and 6 patients with oxalate-related disorders. The cutoff value was determined using the formula (M + 2SD), where (M) is the mean and (SD) is the standard deviation of the healthy sample results. The calculated cutoff value of 0.656750 effectively distinguished between healthy and affected individuals, with a sensitivity of 97.5% and a specificity of 83.3%. These findings provide a valuable tool for the early detection and management of oxalate-related disorders, with significant implications for clinical practice.

SGLT2 Inhibitors and Their Effect on Urolithiasis: Current Evidence and Future Directions.

Urolithiasis (UL) is increasingly prevalent due to rising cardiorenometabolic diseases, posing significant management challenges despite advances in urological techniques. Sodium-glucose cotransporter-2 (SGLT2) inhibitors, primarily used for type 2 diabetes mellitus, chronic kidney disease, and heart failure, have emerged as a potential novel approach for UL treatment. These inhibitors may help reduce the risk of urolithiasis, particularly in patients with diabetes, by improving glycemic control and altering urinary chemistry, which are crucial factors in stone formation. However, the changes in urinary composition induced by SGLT2 inhibitors might also increase the risk of uric acid stone formation. This review evaluates the potential of SGLT2 inhibitors in managing UL, highlighting both the benefits and the risks. While these inhibitors show promise in reducing new and recurrent urinary stones in patients with diabetes, data on their effects in patients without diabetes who form stones are limited. Current human evidence largely comes from post hoc analyses of randomized controlled trials (RCTs) and large-scale database studies, with only one study providing detailed stone composition data. Experimental studies in animal models and cell lines have focused on calcium oxalate (CaOx) stones, showing that SGLT2 inhibitors specifically target CaOx stone formation and related renal inflammation. Although primarily studied for CaOx stones, their potential impact on other calcium-containing stones, such as calcium phosphate, remains promising. Further research is needed to explore their therapeutic potential and optimize treatment strategies.

SMYD2 Promotes Calcium Oxalate-Induced Glycolysis in Renal Tubular Epithelial Cells via PTEN Methylation.

Background/Objectives: Damage to renal tubular cells (RTCs) represents a critical pathological manifestation in calcium oxalate (CaOx) stone disease, but the underlying mechanism remains elusive. Energy metabolism reprogramming is a vital influencer of RTC survival, and SMYD2 is a histone methylation transferase that has been extensively implicated in various metabolic disorders. Hence, this research aimed to identify whether SMYD2 induces the reprogramming of energy metabolism in RTCs exposed to CaOx nephrolithiasis. Methods: Kidney samples were obtained from patients who underwent laparoscopic nephrectomy for non-functioning kidneys caused by nephrolithiasis. The glyoxylate-induced CaOx stone mice model was established and treated with AZ505. The SMYD2-knockout HK-2 cell line was constructed. Histological changes were evaluated by HE, VK, Tunel, Masson stainings. The molecular mechanism was explored through co-immunoprecipitation and western blotting. Results: The results found that SMYD2 upregulation led to energy reprogramming to glycolysis in human kidney tissue samples and in mice with CaOx nephrolithiasis. We also identified the substantial involvement of glycolysis in the induction of apoptosis, inflammation, and epithelial-mesenchymal transition (EMT) in HK-2 cells caused by calcium oxalate monohydrate (COM). In vivo and in vitro results demonstrated that SMYD2 inhibition reduces glycolysis, kidney injury, and fibrosis. Mechanistically, SMYD2 was found to promote metabolic reprogramming of RTCs toward glycolysis by activating the AKT/mTOR pathway via methylated PTEN, which mediates CaOx-induced renal injury and fibrosis. Conclusions: Our findings reveal an epigenetic regulatory role of SMYD2 in metabolic reprogramming in CaOx nephrolithiasis and associated kidney injury, suggesting that targeting SMYD2 and glycolysis may represent a potential therapeutic strategy for CaOx-induced kidney injury and fibrosis.

Expression profiles of urine exosomal tRNA-derived small RNAs and their potential roles in calcium oxalate stone disease

Background and objective: Exosomes have been confirmed to be implicated in the pathogenesis of calcium oxalate (CaOx) stones. tRNA-derived small RNAs (tsRNAs) are among the oldest small RNAs involved in exosome-mediated intercellular communication, yet their role in kidney stones remains unexplored. This pilot study aimed to identify differentially expressed tsRNAs (DEtsRNAs) in urine exosomes between CaOx stone patients and healthy controls and explore their potential roles in nephrolithiasis. Method: First-morning urine samples were collected from three CaOx stone patients and three healthy controls. Urinary exosomes were isolated and analyzed by high-throughput sequencing to generate the expression profiles of tsRNAs and detect DEtsRNAs. Predicted target genes of DEtsRNAs were subjected to functional enrichment analysis. The authors also combined the public dataset GSE73680 to investigate how DEtsRNAs were related to stone formation. Results: Four DEtsRNAs were significantly upregulated in CaOx stone patients compared to healthy controls. tRF-Lys-TTT-5005c was the most elevated, followed by tRF-Lys-CTT-5006c, tRF-Ala-AGC-5017b, and tRF-Gly-CCC-5004b. Bioinformatics analysis indicated that these four types of DEtsRNAs might serve distinct biological functions. Combined with data mining from the public dataset GSE73680, the authors assumed that exosomes carrying tRF-Lys-TTT-5005c and tRF-Lys-CTT-5006c could inhibit the expression of SMAD6, FBN1, and FZD1, thereby activating the BMP signaling pathway, which might induce an osteogenic-like transformation in target cells, resulting in the formation of Randall’s plaques and CaOx stones. Conclusion: The authors’ findings shed light on the potential roles of tsRNAs in the pathogenesis of CaOx stone disease, highlighting exosomal DEtsRNAs as promising diagnostic biomarkers and therapeutic targets in nephrolithiasis.

Kukoamine A alleviates nephrolithiasis by inhibiting endogenous oxalate synthesis via the IL-6/JAK/STAT3/DAO signaling pathway

BackgroundThe recurrent nature and socioeconomic burden of nephrolithiasis demand effective treatments. Delineating the crosstalk between inflammatory processes and the endogenous oxalate metabolism pathway, which underpins nephrolithiasis pathogenesis, is essential for advancing treatment strategies. PurposeWe aim to screen therapeutic Chinese herbal remedies and their bioactive constituents for kidney stone treatment using a fruit fly model, followed by efficacy and mechanism validation in a rodent nephrolithiasis model as well as in vitro human cell culture model. Study design and methodsWe developed a fruit fly model to screen for efficient traditional Chinese medicine herbs and their active compounds for kidney stone treatment. Candidate active compounds from efficient herbs were separated and identified by solid-phase chromatography coupled with LC-MS analysis. Fruit fly genetic tools were employed to manipulate the expression of related genes to explore the therapeutic mechanisms of the Lycii Cortex and kukoamine A (KuA). To confirm the therapeutic effects and mechanisms of KuA for mammalian nephrolithiasis, mouse model of glyoxylate-induced kidney stone and human renal tubular cells were used. The therapeutic role of kukoamine A in nephrolithiasis was evaluated by assessing tubular injury, crystal deposition, and adhesion. The level of expression and phosphorylation in cells and mice was assessed using RT-qPCR and western blot. ResultsOur findings indicate that Lycii Cortex potently inhibits calcium oxalate stone formation via activation of the JNK/Upd3/JAK/STAT signaling cascade, resulting in diminished endogenous oxalate synthesis by downregulating D-amino acid oxidase (DAO) gene expression, predominantly in fruit fly Malpighian tube stellate cells. KuA was identified as the principal bioactive constituent mediating these effects. Both mouse models and human cell assays confirmed KuA's efficacy in preventing calcium oxalate nephrolithiasis in mammals, through hepatic JAK/STAT3 pathway activation and upregulation of IL-6, culminating in reduced urinary crystal deposition. ConclusionOur research underscores the potential of kukoamine A as a lead compound in treating nephrolithiasis and reveals the interplay between the IL-6/JAK/STAT3 inflammatory pathway and endogenous oxalate metabolism in nephrolithiasis pathogenesis. Additionally, it highlights the utility of the fruit fly model as a powerful tool for deciphering the therapeutic mechanisms of traditional Chinese herbs.

S100A9 promotes renal calcium oxalate stone formation via activating the TLR4-p38/MAPK-LCN2 signaling pathway

ObjectivesTo explore the role of S100A9 protein in renal calcium oxalate (CaOx) stone formation. MethodsCaOx nephrocalcinosis mice were established via intraperitoneal injection of glyoxylate. They were treated with S100A9 deficiency, Paquinimod, or p38 MAPK-IN-1. Vonkossa staining was conducted to observe the deposition of CaOx crystals. Renal expression of inflammation, macrophage polarization, and injury markers was detected using immunohistochemistry and qPCR. Effects of S100A9 on renal tubular epithelial cells (HK−2) were explored by transcriptome sequencing. The mechanism of how S100A9 regulated lipocalin 2 (LCN2) was studied through Western Blot. Flow cytometry was performed to detect the influence of LCN2 on macrophages polarization. ResultsS100A9 deficiency inhibited the renal deposition of CaOx crystals in nephrocalcinosis mice. S100A9 upregulated the expression of LCN2 in HK-2 cells via activating the TLR4-p38/MAPK pathway. LCN2 promoted the migration and M1 polarization of macrophages. S100A9 deficiency downregulated the renal expression of LCN2, IL1-β, Kim-1, F4/80, and CD80 in nephrocalcinosis mice. Paquinimod and p38 MAPK-IN-1 both inhibited the renal deposition of CaOx crystals and downregulated the expression of LCN2, IL1-β, Kim-1, F4/80, iNOS, and CD68 in nephrocalcinosis mice. ConclusionsS100A9 promotes renal inflammatory injury by activating the TLR4-p38/MAPK-LCN2 pathway and then contributes to CaOx stone formation.

Two distinct phenotypes of calcium oxalate stone formers could imply different long-term risks for renal function.

Endoscopic and biopsy findings have identified two distinct phenotypes among individuals with calcium oxalate (CaOx) kidney stones. The first type has normal renal papillae but shows interstitial mineral deposition, known as Randall's plaque. The other phenotype presents with collecting duct plugging and a higher incidence of loss of papilla tissue mass. With Randall's plaque, renal papilla injury involves the loss of small patches of calcified tissue (Randall's plaque detaching with the stone), which likely results in damage to only a few nephrons. In contrast, collecting duct mineral plugs are very large, causing obstruction to tubular flow. Since each terminal collecting duct drains thousands of nephrons, ductal plugs could lead to the degeneration of many nephrons and a significant loss of renal glomeruli. New visualization techniques for immune cells in papillary biopsies have revealed that the Randall's plaque phenotype is marked by the accumulation of macrophages around the plaque regions. In contrast, preliminary data on the plugging phenotype shows collecting duct damage with mineral plugsand increased T-lymphocytes throughout the papilla. These regions also show tubulitis, i.e., T-cell infiltration into nearby collecting duct epithelium. This suggests that while some CaOx stone formers may have some papillary inflammation but with minimal damage to nephrons, others suffer from obstruction to flow for many nephrons that may also include destructive inflammation in the renal tissue. We propose that CaOx stone formers with the plugging phenotype will have a higher long-term risk for loss of renal function.

Unraveling the role of gut microbiota by fecal microbiota transplantation in rat model of kidney stone disease

Emerging research on the microbiome highlights the significant role of gut health in the development of kidney stones, indicating that an imbalance in gut bacteria or dysbiosis can influence the formation of stones by altering oxalate metabolism and urinary metabolite profiles. In particular, the overabundance of specific bacteria such as Enterococcus and Oxalobacter spp., which are known to affect oxalate absorption, is observed in patients with urolithiasis. This study investigates the effects of gut dysbiosis on urolithiasis through fecal microbiota transplantation (FMT) from patients to rats and its impact on urinary mineral excretion and stone formation. Fecal samples from eight patients with calcium oxalate stones and ten healthy volunteers were collected to assess the gut microbiome. These samples were then transplanted to antibiotic-pretreated Wistar rats for a duration of four weeks. After transplantation, we evaluated changes in the fecal gut microbiome profile, urinary mineral excretion rates, and expression levels of intestinal zonula occluden-1 (ZO-1), SLC26A6 and renal NF-κB. In humans, patients with urolithiasis exhibited increased urinary calcium and oxalate levels, along with decreased citrate excretion and increased urinary supersaturation index. The fecal microbiota showed a notable abundance of Bacteroidota. In rodents, urolithiasis-FMT rats showed urinary disturbances similar to patients, including elevated pH, oxalate level, and supersaturation index, despite negative renal pathology. In addition, a slight elevation in the expression of renal NF-κB, a significant intestinal SLC26A6, and a reduction in ZO-1 expression were observed. The gut microbiome of urolithiasis-FMT rats showed an increased abundance of Bacteroidota, particularly Muribaculaceae, compared to their healthy FMT counterparts. In conclusion, the consistent overabundance of Bacteroidota in both urolithiasis patients and urolithiasis-FMT rats is related to altered intestinal barrier function, hyperoxaluria, and renal inflammation. These findings suggest that gut dysbiosis, characterized by an overgrowth of Bacteroidota, plays a crucial role in the pathogenesis of calcium oxalate urolithiasis, underscoring the potential of targeting the gut microbiota as a therapeutic strategy.

The direct inhibitory effects of Lactobacillus acidophilus, a commensal urinary bacterium, on calcium oxalate stone development

BackgroundLactobacillus acidophilus is a commensal urinary bacterium found more abundantly in healthy individuals than in stone patients. Hence, it has been proposed to play an inhibitory role in kidney stone disease (KSD) but with unclear mechanisms. We therefore investigated the direct effects of L. acidophilus on calcium oxalate (CaOx) stone development compared with Escherichia coli, which is known to promote CaOx stone formation.ResultsL. acidophilus at 1 × 103 CFU/ml significantly reduced the abundance of newly formed crystals, enlargement and aggregation of seeded crystals, and crystal adhesion on renal cell membranes. By contrast, E. coli at 1 × 103 CFU/ml significantly enhanced crystal growth and aggregation but did not affect crystallization and crystal-cell adhesion. Oxalate consumption assay showed that neither L. acidophilus nor E. coli significantly reduced the remaining oxalate level after 1 − 3 h incubation. However, both of them adhered to CaOx crystals. Surface component detection revealed that only L. acidophilus expressed S-layer protein, whereas only E. coli exhibited flagella on their surfaces. Removal of L. acidophilus S-layer protein and E. coli flagella completely abolished the inhibitory and promoting effects of L. acidophilus and E. coli, respectively.ConclusionsL. acidophilus inhibits CaOx stone development by hampering crystallization, growth, aggregation and cell-adhesive ability of CaOx. By contrast, E. coli enhances CaOx stone development by promoting CaOx growth and aggregation. Their contradictory effects are most likely from differential surface components (i.e., S-layer protein on L. acidophilus and flagella on E. coli) not from oxalate-degrading ability.D_jrSVq7xgjsSvuNUfqm6AVideo

Comparison of cat stone matrix and cat urine proteomes to human calcium oxalate stone matrix and urine proteomes.

Cat calcium oxalate monohydrate kidney stone matrix proteome showed great similarity to human calcium oxalate monohydrate stone matrix proteome, but inference of mechanistic similarity was limited by the absence of cat urine proteomic data. In this study, urine proteome distributions were measured by the same methods in 7 healthy cats for comparison to both the published human urine and cat calcium oxalate stone matrix proteomes to assess for similar enrichment patterns in both species. Furthermore, proteomic distributions were determined in cat struvite stone matrix to test for similarity to calcium oxalate monohydrate stone matrix and urine proteomes. Cat urine proteins demonstrated a similar distribution of abundance as a function of isoelectric points or net charge to human urine samples, and consequently the similarly altered patterns of protein distributions seen in calcium oxalate monohydrate stone matrix seen from both cat and human stones likely derives from the same preferential adsorption mechanism. Furthermore, the fact that protein abundance patterns seen in cat struvite stone matrix samples differ from both urine and calcium oxalate monohydrate stone matrix proteomes in systematic ways suggests that a combination of protein-protein and protein crystal interactions underly the formation of the crystal aggregates that comprise stones.

Two distinct phenotypes of calcium oxalate stone formers could imply different long-term risks for renal function.

Endoscopic and biopsy findings have identified two distinct phenotypes among individuals with calcium oxalate (CaOx) kidney stones. One phenotype exhibits normal renal papillae but shows interstitial mineral deposition, known as Randall's plaque. The other phenotype presents with collecting duct plugging and a higher incidence of loss of papilla tissue mass. With Randall's plaque, renal papilla injury involves the loss of small patches of calcified tissue (Randall's plaque detaching with the stone), which likely results in damage to only a few nephrons. In contrast, collecting duct mineral plugs are very large, causing obstruction to tubular flow. Since each terminal collecting duct drains thousands of nephrons, ductal plugs could lead to the degeneration of many nephrons and a significant loss of renal glomeruli. New visualization techniques for immune cells in papillary biopsies have revealed that the Randall's plaque phenotype is marked by the accumulation of macrophages around the plaque regions. In contrast, preliminary data on the plugging phenotype shows collecting duct damage with mineral plugs, increased T-lymphocytes throughout the papilla, and tubulitis, characterized by T-cell infiltration into nearby collecting duct epithelium. This suggests that while some CaOx stone formers may have some papillary inflammation but with minimal damage to nephrons, others suffer from obstruction to flow for many nephrons that may also include destructive inflammation in the renal tissue. We propose that the long-term risks for loss of renal function will be greater for CaOx stone formers with the plugging phenotype.

Defining physicochemical properties of urinary proteins that determine their inhibitory activities against calcium oxalate kidney stone formation

We have recently reported a set of urinary proteins that inhibited calcium oxalate (CaOx) stone development. However, physicochemical properties that determine their inhibitory activities remained unknown. Herein, human urinary proteins were chromatographically fractionated into 15 fractions and subjected to various CaOx crystal assays and identification by nanoLC-ESI-Qq-TOF MS/MS. Their physicochemical properties and crystal inhibitory activities were subjected to Pearson correlation analysis. The data showed that almost all urinary protein fractions had crystal inhibitory activities. Up to 128 proteins were identified from each fraction. Crystallization inhibitory activity correlated with percentages of Ca2+-binding proteins, stable proteins, polar amino acids, alpha helix, beta turn, and random coil, but inversely correlated with number of Ox2−-binding motifs/protein and percentage of unstable proteins. Crystal aggregation inhibitory activity correlated with percentage of stable proteins but inversely correlated with percentage of unstable proteins. Crystal adhesion inhibitory activity correlated with percentage of stable proteins and GRAVY, but inversely correlated with pI, instability index and percentages of unstable proteins and positively charged amino acids. However, there was no correlation between crystal growth inhibitory activity and any physicochemical properties. In summary, some physicochemical properties of urinary proteins can determine and may be able to predict their CaOx stone inhibitory activities.

A high-calcium environment induced ectopic calcification ofrenal interstitial fibroblasts via TFPI-2-DCHS1-ALP/ENPP1 axis to participate inRandall's plaque formation.

Randall's plaques (RP) serve as anchoring sites for calcium oxalate (CaOx) stones, but the underlying mechanism remains unclear. Renal interstitium with a high-calcium environment is identified as pathogenesis of RP formation where the role of human renal interstitial fibroblasts (hRIFs) was highlighted. Our study aims to elucidate the potential mechanism by which a high-calcium environment drives ectopic calcification of hRIFs to participate in RP formation. Alizarin Red staining demonstrated calcium nodules in hRIFs treated with high-calcium medium. Utilizing transcriptome sequencing, tissue factor pathway inhibitor-2 (TFPI-2) was found to be upregulated in high-calcium-induced hRIFs and RP tissues, and TFPI-2 promoted high-calcium-induced calcification of hRIFs. Subsequently, the downstream regulator of TFPI2 was screened by transcriptome sequencing analysis of hRIFs with TFPI-2 knockdown or overexpressed. Dachsous Cadherin Related 1 (DCHS1) knockdown was identified to suppress the calcification of hRIFs enhanced by TFPI-2. Further investigation revealed that TFPI-2/DCHS1 axis promoted high-calcium-induced calcification of hRIFs via disturbing the balance of ENPP1/ALP activities, but without effect on the canonical osteogenic markers, such as osteopontin (OPN), osteogenic factors runt-related transcription factor 2 (RUNX2), bone morphogenetic protein 2 (BMP2). In summary, our study mimicked the high-calcium environment observed in CaOx stone patients with hypercalciuria, and discovered that the high-calcium drove ectopic calcification of hRIFs via a novel TFPI-2-DCHS1-ALP/ENPP1 pathway rather than adaption of osteogenic phenotypes to participate in RP formation.

A review: evaluating methods for analyzing kidney stones and investigating the influence of major and trace elements on their formation

Abstract Kidney stone disease is a global concern, and its prevalence is increasing. The objective of this review is to provide a thorough analysis of the many analytical techniques used in the study of kidney stones and to investigate the significance of major and trace components in the development of kidney stone formation. The samples included organic (uric acid) and inorganic (calcium oxalate and carbonate apatite). To study kidney stone analysis methods like XRD, FTIR, SEM, and ICP-MS, a systematic literature review was conducted. The quantities and effects of main (calcium, oxalate, phosphate) and trace (magnesium, zinc, copper) elements in kidney stone development were also examined. The review shows that XRD and FTIR are best for evaluating kidney stone crystalline structure and content, whereas SEM gives rich morphological insights. Its trace element detection sensitivity makes ICP-MS unique. Calcium oxalate and calcium phosphate, the most common components, affect kidney stone development. Trace elements like magnesium prevent stone formation, whereas zinc and copper may encourage crystallisation. Results revealed significantly higher calcium levels in inorganic components compared to organic ones. Uric acid stones exhibited lower element content except for copper and selenium, likely originating from the liver. Carbonate apatite stones showed higher element concentrations, particularly magnesium, compared to calcium oxalate stones. Principal component analysis (PCA) identified three principal components, explaining 91.91 % of the variance. These components reflected specific co-precipitation processes of elements, with distinct distributions among different stone types. This variability in element content among stone types could serve as valuable guidance for patient dietary considerations.

Long-Term Follow-up Results of Children with Urolithiasis Followed in Our Clinic

Title and Objective: Urolithiasis is a prevalent condition frequently observed in childhood within the Turkish population. The aim of this study was to evaluate the metabolic, radiological, and clinical features of pediatric patients with urolithiasis. Materials and Methods: Records of 158 children referred to the Pediatric Nephrology Department of Celal Bayar University between 2010 and 2020 with suspected urolithiasis and microlithiasis were retrospectively reviewed. The complaints and ages of the cases during hospital admission, their medical histories, and the location of the stones were determined. All patients underwent complete urine analysis, spot urine electrolytes, urine culture, serum electrolytes, kidney function tests, uric acid, albumin measurements, and urinary ultrasonography. 24-hour urine electrolytes were studied in patients capable of urine collection. Stone analysis using X-ray diffraction was performed on patients from whom stones were obtained. Results: Out of the individuals, 88 (55.7%) were male, and 70 (44.3%) were female, resulting in a male-to-female ratio of 1.25:1. The average age at the time of diagnosis was determined to be 89.82 ± 57.35 months. A family history of urolithiasis was reported in 108 (68.3%) patients, and 46 individuals (29%) were born from consanguineous marriages. At the time of diagnosis, 32 patients (20%) had a urinary tract infection. Stones were predominantly situated in the upper urinary system in 129 patients (81.6%), with 123 (77.8%) having unilateral stones and 35 (22.2%) having bilateral stones. Calcium oxalate stones were the most commonly observed (80%) in patients who underwent stone analysis. Hypercalciuria emerged as the most frequently identified urinary metabolic risk factor. At the end of the follow-up period, 14 patients experienced a recurrence, while 67 patients remained free of stones. Conclusion: Urolithiasis continues to be a significant concern among children in our nation. Due to the higher recurrence rate and more frequent underlying metabolic disorders in children with stone diseases compared to adults, metabolic assessment and stone analysis are recommended procedures, emphasizing the need for lifelong monitoring in these cases.

Metabolic Profile of Calcium Oxalate Stone Patients with Enteric Hyperoxaluria and Impact of Dietary Intervention.

This study investigated the risk profile and the impact of dietary intervention in calcium oxalate stone formers with enteric hyperoxaluria under controlled, standardized conditions. Thirty-seven patients were included in the study. Dietary and 24-h urinary parameters were obtained on the self-selected diet and a balanced, standardized diet. Tests for [13C2]oxalate absorption, calcium- and ammonium chloride-loading were performed. Mean [13C2]oxalate absorption was 18.8%. A significant positive association was observed between urinary oxalate excretion and intestinal oxalate absorption. In addition, urinary oxalate excretion was significantly correlated with dietary oxalate intake. Mean urinary oxalate excretion decreased from 0.841 mmol/24 h on the usual diet to 0.662 mmol/24 h on the balanced diet, corresponding to a reduction of 21.3%. Besides hyperoxaluria, hypocitraturia and hypomagnesuria were the most common urinary abnormalities at baseline, being present in 83.8% and 81.1% of patients, respectively. Urinary citrate increased by 50.9% and magnesium excretion increased by 25.2% on the balanced diet. As a result, the relative supersaturation of calcium oxalate declined significantly (by 36.2%) on the balanced diet. Since 41% of patients on the balanced diet still had a urine volume of less than 2.0 L/24 h, efforts should be made to increase urine volume by increasing fluid intake and reducing intestinal fluid losses. Dietary intervention proved to be effective in reducing urinary oxalate excretion and should be a cornerstone of the treatment of patients with enteric hyperoxaluria.

Determination of the kidney stone composition using infrared spectroscopy in Iran at a national referral center during 2019–2023

ObjectiveThe national lifetime prevalence of urolithiasis is estimated at 6.6% in Iran. However, reports on the composition of kidney stones have been based on imprecise methods like chemical analysis. No prior large-scale study has reported the composition of kidney stones based on the gold-standard methods (X-ray diffraction or infrared spectroscopy) in Iran. This study aimed to provide the composition of kidney stones based on Fourier transform infrared. MethodsThis is a cross-sectional study assessing urinary stone composition from various cities in Iran at a referral center using infrared spectroscopy from February 2019 to March 2023. ResultsThis study determined the stone composition of 1092 samples from 10 cities or provinces in Iran. Overall, the majority of stones were composed of calcium (n=522; 47.8%), uric acid (UA, n=488; 44.7%) followed by cystine (n=49; 4.5%), and struvite (n=28; 2.6%). Stone composition in Shiraz and Isfahan was roughly similar with a higher percentage of UA stones (53.4% and 53.6%, respectively) while the capital city of Iran (Tehran) had less frequent UA stones (39.9%) with a higher percentage of calcium oxalate stones. The percentage of UA stones increased with age as it was 11.1% in children, 42.7% in adults, and 83.3% in geriatric patients (p<0.001). About 29.6% of cystine stones were observed in children. ConclusionThe most frequent stone composition among kidney stones in Iran were calcium oxalate and UA stones. This relative frequency of UA stones is considerably higher than many international reports from neighboring as well as distant countries. More cystine stones were observed in children and women. Geriatric patients’ stones were mostly composed of UA.

Comparison of two methods for treatment of 1-2cm kidney stones in pediatric patients: mini PCNL and RIRS.

This study aimed to compare the results of retrograde intrarenal surgery (RIRS) and mini-percutaneous nephrolithotomy (mini-PCNL) for the treatment of 1-2cm kidney stones in pediatric patients. The records of patients under the age of 18 years who were diagnosed with unilateral 1-2cm kidney stones for the first time and underwent endoscopic surgery between February 2008 and April 2022 were retrospectively examined. The patients were divided into two groups: mini-PCNL and RIRS surgery. Parameters such as age, gender, number of stones, side, size and localization were examined. The main endpoint of the study was to compare stone-free rates (SFR) one month after both surgeries. Surgery and fluoroscopy times, postoperative hospital stay, hemoglobin decrease and complication rates were compared between the groups. SFR was evaluated one month after surgery by direct urinary system radiography and USG or CT. A total of 58 patients were included in the study. There were 35 patients in the mini-PCNL group and 23 patients in the RIRS group. Table1 shows the demographic and clinical characteristics of both groups. There was no significant difference between the groups in terms of age, gender, stone size, location, side and density. Calcium oxalate stones were observed at a higher rate in both groups. Mean fluoroscopy time was higher in the mini-PCNL group (p = 0.001). The mean surgery time was lower in the mini-PCNL group (p = 0.024). The mean hemoglobin decrease was greater in the percutaneous group (p = 0.039). There were no differences between the groups in terms of postoperative hospital stay, complication rates, and SFR one month after surgery. Although mini-PCNL seems to be more advantageous in terms of operation time compared to RIRS, it is disadvantageous in terms of average fluoroscopy time, radiation received and average hemoglobin decrease.