Inflammation and kidney stones: cause and effect?

Cross ethnic Mendelian randomization analysis reveals causal relationship between air pollution and risk of kidney stones

Accumulating evidence has indicated that exposures to air pollution increase the odds of kidney stones. However, the previous research methods were limited. To address this gap, we employed genome-wide association studies (GWAS) datasets and Mendelian randomization (MR) to verify the causation. Applying publicly accessible summary datasets from UK Biobank, FinnGen consortium and Biobank Japan, a two-sample MR, and further multivariate MR were carried out to calculate the causality between air pollution [particulate matter 2.5 (PM2.5), PM2.5 absorbance, PM2.5-10, PM10, nitrogen dioxide, and nitrogen oxides] and kidney stone risk in three different populations (European, East Asian, and South Asian). The inverse variance weighted (IVW) was utilized for its first-step assessment, supplemented with MR-Egger, weighted median, Cochran's Q test, MR-Egger intercept and leave-one-out analysis to ensure the robustness. Employing IVW, we discovered in the European population that PM2.5 absorbance was statistically correlated with kidney stone risk (odds ratio (OR) = 1.40; 95% confidence interval (CI), 1.01-1.94; P = 0.04), with no heterogeneity, pleiotropy, or sensitivity observed. Additionally, the MVMR result revealed the directly causative connection between a single PM2.5 absorbance and the increase in kidney stone risk (OR = 1.77, 95%CI: 1.06-2.98, p = 0.03). Our investigation proposed the correlation between PM2.5 absorbance and an increased risk of kidney stones in European populations. The control of air pollution, especially PM2.5, may have crucial implications for the prevention of kidney stones.

Effect of the plasma metabolites, biomarkers, and inflammatory proteins on urolithiasis: insights from Mendelian randomization and mediation analysis

Urolithiasis represents a systemic disorder characterized by metabolic circulation issues and ongoing inflammation. The purpose of this research is to explore the relationships of causation among plasma metabolites, biomarkers, inflammatory proteins, and stones within the urinary system. We initially carried out a two-sample Mendelian randomization (MR) analysis to evaluate possible causal connections between 233 plasma metabolites and 35 biomarkers related to urolithiasis. The genetic association study (GWAS) data concerning plasma metabolites were derived from a 2024 publication in Nature, while data for biomarkers were collected from the UK Biobank. To determine causal relationships, we utilized several analytical techniques, including inverse variance weighting (IVW), MR-Egger, weighted median, and weighted mode. Furthermore, we conducted analyses for pleiotropy and heterogeneity to ensure the findings' robustness. A Steiger analysis was used to explore the presence of any reverse causal relationships. Lastly, we conducted mediation analysis to elucidate how inflammatory proteins mediate the associations between plasma metabolites, biomarkers, and stones in the urinary system. Our research demonstrates causal connections between six plasma metabolites and six biomarkers related to upper urinary tract stones. Furthermore, we identified causal associations between ten plasma metabolites and four biomarkers linked to lower urinary tract stones. Most of these metabolites belong to lipid and lipoprotein classes, indicating that changes in blood lipid levels may influence stone formation. Finally, mediation analysis revealed 13 mediating relationships, including the mediating effects of six inflammatory proteins. Our results provide evidence for the causal links among plasma metabolites, biomarkers, and inflammatory proteins associated with urolithiasis. This provides new insights into the potential mechanisms underlying urinary system stone formation, contributing to their prevention, diagnosis, and treatment.

Neutrophils as mediators of the association between lipid accumulation product and kidney stones, but not for recurrent kidney stones in US adults

Kidney stones (KS) are prevalent and often recur, with obesity, metabolic disorders, and inflammation significantly impacting their pathophysiology. The traditional body mass index (BMI) has limitations, as it cannot effectively differentiate between fat and lean body mass or provide information about fat distribution. In contrast, the lipid accumulation product (LAP), which combines waist circumference and triglyceride levels, serves as a crucial indicator of visceral fat. This study examines the relationship between LAP and KS, including recurrent kidney stones (RKS), using data from the National Health and Nutrition Examination Survey (NHANES). It also investigates whether neutrophils mediate the connection between LAP and KS/RKS, comparing the predictive accuracy of LAP and BMI. Data from 2007 to 2014 covered 9910 KS participants and 880 RKS participants. Weighted logistic regression assessed the LAP-KS/RKS relationship, while mediation analysis explored the role of neutrophils. Receiver Operating Characteristic (ROC) curves evaluated the predictive capabilities of LAP and BMI. Results showed LAP was significantly associated with KS (OR = 1.629; 95% CI 1.296-2.047) and RKS (OR = 1.561; 95% CI 1.145-2.128). Neutrophils partially mediated the LAP-KS relationship (7.6%, p = 0.018), with no effect found for RKS. Moreover, LAP outperformed BMI in diagnostic accuracy. These findings suggest that LAP is an effective marker for assessing KS and RKS, aiding in the early identification of potential patients to reduce the incidence and recurrence of kidney stones.

The influence and relationship of dysbiosis in the urinary microbiota on patients with urolithiasis

Urolithiasis is a disease with high prevalence and recurrence rate. There are various risk factors impacting on stone formation including intestinal micorbiota. This study aims to investigate the relationship between urine microbiota with urolithiasis. We collected mid-stream voided urine samples from urolithiasis patients and control participants and stored them in a freezer at - 80 °C. All enrolled participants were requested to provide information about their clinical characteristics. The procedure included the extraction of the genomic DNA from the urine samples; the amplification by polymerase chain reaction (PCR); PCR product quantification, mixing, and purification; DNA library preparation; and sequencing was performed with quality control (QC) measures. Alpha diversity was indicative of the species complexity within individual urine samples, and beta diversity analysis was used to evaluate the differences among the samples in terms of species complexity. We enrolled 28 urolithiasis patients and 59 control participants who reported no recent antibiotic usage. In the beta diversity analysis, there was a significant difference between the microbiota in the samples of the urolithiasis and control groups according to ANOSIM statistical analysis. (P = 0.004). On comparing the groups, it showed Alcaligenes, Bacteroides, Blautia, Ruminococcaceae_UCG, Cutibacterium, Alistipes, Lachnoclostridium present more significant in control group than urolithiasis patients. In conclusion, our current study shows that dysbiosis of urine microbiota may be related to the development of urolithiasis. Further research targeting specific microbes to identify their role in the development of diseases is necessary and might provide novel diagnostic biomarkers and therapeutic options.

Associations between cardiometabolic index with kidney stones: evidence from NHANES 2007-2018

Background

Kidney stones are a prevalent disorder that is linked to a range of metabolic variables. The cardiometabolic index (CMI) is a newly developed combined measure used to evaluate the state of cardiometabolic health. Nevertheless, the association between CMI and kidney stone remains little investigated.

Methods

In this study, cross-sectional analysis was done on NHANES data from 2007 to 2018. The association between the prevalence of kidney stones and the CMI was investigated using a logistic regression analysis. To look into the nonlinear link between them, we used restricted cubic spline (RCS) analysis. The study was made more reliable and accurate by using sensitivity analysis and subgroup analysis to look for factors that may have contributed to the different results.

Results

A significant association was seen between increased CMI and the prevalence of kidney stones (OR = 1.19, 95% CI: 1.06-1.32). The RCS analysis revealed crucial CMI values that exhibited a robust association within a certain range. Subgroup studies revealed that this link was particularly prominent among those below the age of 50, females, obese, CKD and diabetes patients. The dependability of the study's conclusions was further established using sensitivity analysis.

Conclusion

This study established a notable association between CMI and a higher prevalence of kidney stones, emphasizing the significance of CMI as a comprehensive measure for evaluating metabolic risk. Furthermore, it suggests that monitoring CMI levels could be beneficial in identifying populations with a high prevalence of kidney stones.

Characterization of the gut microbiota in urinary calculi patients with preoperative urinary tract infection

Background

Urinary tract infection is one of the most common comorbidities of urinary stones. Disorders of gut microbiota can affect various infectious diseases and the formation of the stones. Therefore, alterations in the gut bacteria profile may be a potential risk factor for the development of infections in patients with urinary tract stones.

Methods

We conducted a retrospective study to analyze the association of urinary tract infections with gut microbiota and serum metabolism in patients with stones.

Results

Patients with urolithiasis were predominantly in combination with diabetes mellitus (11.4% vs. 20%) and hypertension (36.4% vs. 50%). There were no statistically significant differences in hematological and urinary parameters. Compared to negative patients, IL-17A was significantly higher in the positive group (25.0 vs 21.1 pg/ml p = 0.038). The majority of pathogens detected in urine cultures were urease-negative bacteria, and urease-positive bacteria accounted for 15% of the total number of patients. We analyzed the community composition of the two groups of patients and found a significant difference in their β-diversity (p = 0.025), suggesting that dysbiosis of the gut bacteria may be associated with the combination of urinary tract infections in urolithiasis. For identification of crucial bacteria, we found changes in the abundance of both Intestinibacter (p = 0.036) and Dialister (p = 0.039), and abundance of Intestinibacter was positively correlated with IFN-α, IL-12P70 (p<0.05), and especially IL-17A (p<0.01), which may result from differences in translational, ribosomal structural and biosynthetic functions in stone patients (p < 0.05).

Conclusion

Urolithiasis with gut dysbiosis developed a higher incidence of urinary tract infections, which may be associated with the increasing of Intestinibacter and affect the expression of IL-17A by translational, ribosomal structural and biosynthetic function.

Microarchitecture and Crystalline Composition: A Comprehensive Exploration of Salivary Gland Stones

OBJECTIVE

To investigate the microarchitecture and crystalline composition of sialoliths and to explore their formation mechanisms.

METHODS

Sixty-six sialolith samples (51 from the submandibular glands and 15 from the parotid glands) were retrospectively collected. Their diameter and quality were measured. Micro-computed tomography, scanning electron microscopy, and polycrystalline X-ray diffractometer (XRD) were utilized to determine their microstructure and crystalline composition.

RESULTS

Stone diameter and weight averaged at 9.6 mm and 0.31 g, respectively. Submandibular stones showed larger size and weight than parotid stones. Microstructurally, the main stones were concentric (n = 51) or mixed (n = 15). Most concentric stones occurred at submandibular glands, while 80% of the mixed stones were parotid stones. Stone surface exhibited three microscopic structures: lamellar, grape-like, and porous, indicating their differences in mineralization process and composition. XRD revealed that all stones contained hydroxyapatite, with 57 containing whitlockite. Concentration of hydroxyapatite in concentric stones was significantly higher than that in mixed stones (p = 0.036) and correlated positively with stone diameter (p = 0.001). The microstructure and crystalline composition of multiple and recurrent stones were similar to that of single stones.

CONCLUSION

Sialoliths display pronounced diversity in microarchitecture and crystalline composition, reflecting the differences in mineralization process and local microenvironments among stones.

N-acetyltransferase 10 regulates UNC-51-like kinase 1 to reduce tubular cell injury and kidney stone formation

Objective

Among the most common chronic kidney diseases, kidney stones are second only to hypertension. Kidney stones pose a public health threat due to their increased incidence, high recurrence rate, and heavy economic burden. In this work, we investigated the potential mechanism of N-acetyltransferase 10 (NAT10) in oxidative stress and pyroptosis of renal tubular epithelial cells (RTECs).

Material and Methods

A kidney-stone cell model was simulated using calcium oxalate monohydrate (COM) in vitro. Western blot analysis of NAT10 expression and N4-acetylcytidine RNA immunoprecipitation verified the regulatory efficacy of NAT10 in Unc-51 like autophagy activating kinase 1 (ULK1) ac4C modification. The luciferase reporter gene assay further verified the interaction between NAT10 and ULK1. A kidney stone model was established using BALB/c mice injected with glyoxylic acid.

Results

COM can dose-dependently suppressed the cell viability and superoxide dismutase activity of HK-2 cells and promoted the release of lactate dehydrogenase and malondialdehyde levels (P < 0.05). COM also promoted apoptosis in HK-2 cells, upregulated the protein levels of caspase-1 and gasdermin D-N, and simultaneously enhanced the HK-2 cell secretion of interleukin-1b (IL-1b) and IL-18 (P < 0.05). The overexpression of NAT10 in HK-2 cells reversed the aforementioned effects, and that of NAT10 upregulated the messenger RNA (mRNA) levels of ULK1 and increased ac4C modification (P < 0.01). Furthermore, only the luciferase activity of the wild-type ULK1 containing NAT10 binding sites was enhanced with the upregulation of NAT10 (P < 0.001). Actinomycin D treatment showed that NAT10 overexpression extended the half-life of ULK1 mRNA (P < 0.01). Silencing of ULK1 neutralized the effects of NAT10 overexpression on COM-induced cell injury (P < 0.05). In addition, the increased expression of NAT10 inhibited crystal deposition, oxidative stress, and apoptosis in vivo (P < 0.05).

Conclusion

This study confirmed that NAT10 inhibits RTECs oxidative stress and cell pyrodeath through the enhanced ac4C modification of ULK1 and impedes kidney stone progression.

Suppression of renal crystal formation, inflammation, and fibrosis by blocking oncostatin M receptor β signaling

Oncostatin M (OSM) has pleiotropic effects on various inflammatory diseases, including kidney stone disease. The prevalence of kidney stones has increased worldwide, despite recent therapeutic advances, due to its high recurrence rate, suggesting the importance of prevention of repeated recurrence in the treatment of kidney stone disease. Using a mouse model of renal crystal formation, we investigated the preventive effects of blockade of OSM receptor β (OSMRβ) signaling on the development of kidney stone disease by treatment with a monoclonal anti-OSMRβ antibody that we generated. The anti-OSMRβ antibody abrogated OSM-induced phosphorylation of STAT3 and expression of crystal-binding molecules (Opn, Anxa1, Anxa2) and inflammation/fibrosis-associated molecules (Tnfa, Tgfb, Col1a2) in renal tubular epithelial cells and fibroblasts. In glyoxylate-injected mice, a mouse model of renal crystal formation, there was significant suppression of crystal deposits and expression of crystal-binding molecules (Opn, Anxa1, Anxa2), a tubular injury marker (Kim-1), and inflammation/fibrosis-associated molecules (Tnfa, Il1b, Mcp-1, Tgfb, Col1a2) in the kidneys of the anti-OSMRβ antibody-treated mice, compared with those in vehicle- or isotype control antibody-treated mice. In addition, treatment with the anti-OSMRβ antibody significantly decreased infiltrating macrophages and fibrosis in the kidneys. These findings suggest that anti-OSMRβ antibody-treatment may be effective in preventing kidney stone disease.

Relation between Urine Cytological Findings and Renal Function in Patients with Kidney Stones in Taif, Saudi Arabia

Background and Objectives: Urine serves as a vital diagnostic fluid, and urine cytology analysis plays a crucial role in identifying urinary system illnesses such as bladder cancer and kidney stones. The Paris System for Reporting Urinary Cytology establishes a uniform method for diagnosing urinary tract cancer. This study aimed to provide valuable insights that can inform diagnostic strategies related to kidney stones and ultimately improve patient outcomes via the early detection of the cellular changes associated with kidney stones and their relation to kidney function tests. Materials and Methods: A comparative study was conducted and comprised two groups: group 1, consisting of 50 patients diagnosed with kidney stones, and group 2, comprising 50 patients diagnosed with other kidney diseases. Renal function tests and urinalysis (via the PAP staining of urine cellular deposits to detect nuclear changes) were performed, and the results were analyzed. Results: There was a statistically significant increase in urinary red blood cells, white blood cells, and nuclear reactive atypical changes in urinary sediments of kidney stone patients compared to the patients without stones, while there was a decrease in the estimated glomerular filtration rate (eGFR). eGFR showed a 96.7% specificity in detecting cases with nuclear reactive atypia. Conclusions: eGFR emerges as a reliable diagnostic marker for the comprehensive assessment of kidney stones, particularly when associated with nuclear atypia. The significant correlation between the indicators of chronic kidney disease, such as decreased eGFR, and the presence of kidney stones emphasizes the urgent need for efficient diagnostic practices.

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 plugs and 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.

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.

High composite dietary antioxidant index is associated with reduced risk of kidney stones: a cross-sectional analysis of NHANES 2007-2020

The composite dietary antioxidant index (CDAI) is commonly utilized to assess antioxidant intake across diseases, but its association with kidney stones is unclear. We hypothesized that higher CDAI is associated with reduced kidney stone risk. Using National Health and Nutrition Examination Survey 2007-2020 data, we calculated CDAI based on vitamins A, C, E, selenium, zinc, and carotenoids intake in 29,280 adults. Stone formers had lower CDAI, with significant gender differences. Restricted cubic spline showed an L-shaped curve, with the steepest decline before CDAI of 1.449. In multivariate logistic regression, moderate and high CDAI tertiles were associated with reduced kidney stone odds compared to the lowest tertile (odds ratio [95% CI]): 0.85 [0.73, 0.99], P = .035 and 0.80 [0.66, 0.95], P = .014, respectively). Vitamin C had the highest negative correlation weight with kidney stones. Significant interactions were found for age and diabetes subgroups. In conclusion, higher CDAI may reduce kidney stone risk, especially with adequate vitamin C intake. Further cohort studies are warranted to confirm the causal association.

Understanding formation processes of calcareous nephrolithiasis in renal interstitium and tubule lumen

Kidney stone, one of the oldest known diseases, has plagued humans for centuries, consistently imposing a heavy burden on patients and healthcare systems worldwide due to their high incidence and recurrence rates. Advancements in endoscopy, imaging, genetics, molecular biology and bioinformatics have led to a deeper and more comprehensive understanding of the mechanism behind nephrolithiasis. Kidney stone formation is a complex, multi-step and long-term process involving the transformation of stone-forming salts from free ions into asymptomatic or symptomatic stones influenced by physical, chemical and biological factors. Among the various types of kidney stones observed in clinical practice, calcareous nephrolithiasis is currently the most common and exhibits the most intricate formation mechanism. Extensive research suggests that calcareous nephrolithiasis primarily originates from interstitial subepithelial calcified plaques and/or calcified blockages in the openings of collecting ducts. These calcified plaques and blockages eventually come into contact with urine in the renal pelvis, serving as a nidus for crystal formation and subsequent stone growth. Both pathways of stone formation share similar mechanisms, such as the drive of abnormal urine composition, involvement of oxidative stress and inflammation, and an imbalance of stone inhibitors and promoters. However, they also possess unique characteristics. Hence, this review aims to provide detailed description and present recent discoveries regarding the formation processes of calcareous nephrolithiasis from two distinct birthplaces: renal interstitium and tubule lumen.

Prevalence and associated factors for asymptomatic microscopic hematuria in adults in the PERSIAN Guilan cohort study (PGCS)

Although hematuria is not life-threatening, some could be the result of a more severe condition. Our objectives are to report on the prevalence and risk factors of asymptomatic microscopic hematuria (AMH) in the prospective epidemiological research studies of the Iranian adults (PERSIAN) Guilan cohort study (PGCS) population. This cross-sectional study was conducted from 2014 to 2017 and consisted of 10,520 individuals aged 35-70. Data collection was conducted using a questionnaire during a face-to-face interview. The urine analyses (UA) were done up to 2 h after sample collection. Based on a urine microscopy evaluation, AMH is defined as 3 or more red blood cells per high power field (HPF). Simple and multiple logistic regression analysis was conducted to explore factors associated with AMH. The prevalence of AMH in this study was 34.1% and was more prevalent in participants of older ages and female gender as well as those with low educational level, underweight-body mass index (BMI), high physical activity, smoking, alcohol consumption, and kidney stone disease. On the other hand, obesity, opium, and diabetes decreased the likelihood of AMH. The results of the present study shed light on the prevalence and risk factors of AMH and suggested that a significant portion of the study population is affected by AMH. Considering the lack of consensus on a definite clinical guideline for AMH in our country, the results of the present study could be used to design a unit algorithm for screening and therapy of AMH.

Downregulating miR-184 relieves calcium oxalate crystal-mediated renal cell damage via activating the Rap1 signaling pathway

BACKGROUND

Renal calculi are a very prevalent disease with a high incidence. Calcium oxalate (CaOx) is a primary constituent of kidney stones. Our paper probes the regulatory function and mechanism of miR-184 in CaOx-mediated renal cell damage.

METHODS

CaOx was used to treat HK2 cells and human podocytes (HPCs) to simulate kidney cell damage. The qRT-PCR technique checked the profiles of miR-184 and IGF1R. The examination of cell proliferation was conducted employing CCK8. TUNEL staining was used to monitor cell apoptosis. Western blot analysis was used to determine the protein profiles of apoptosis-concerned related proteins (including Mcl1, Bcl-XL, and Caspase-3), the NF-κB, Nrf2/HO-1, and Rap1 signaling pathways. ELISA confirmed the levels of the inflammatory factors IL-6, TNF-α, MCP1, and ICAM1. The targeting relationship between miR-184 and IGF1R was validated by dual luciferase assay and RNA immunoprecipitation assay.

RESULTS

Glyoxylate-induced rat kidney stones model and HK2 and HPC cells treated with CaOx demonstrated an increase in the miR-184 profile. Inhibiting miR-184 relieved CaOx-mediated renal cell inflammation, apoptosis and oxidative stress and activated the Rap1 pathway. IGF1R was targeted by miR-184. IGF1R activation by IGF1 attenuated the effects of miR-184 on renal cell damage, and Hippo pathway suppression reversed the inhibitory effect of miR-184 knockdown on renal cell impairment.

CONCLUSIONS

miR-184 downregulation activates the Rap1 signaling pathway to ameliorate renal cell damage mediated by CaOx.

Quercetin inhibits calcium oxalate crystallization and growth but promotes crystal aggregation and invasion

Recent evidence has shown an association between kidney stone pathogenesis and oxidative stress. Many anti-oxidants have been studied with an aim for stone prevention. Quercetin, a natural flavonol, is one among those eminent anti-oxidants with satisfactory anti-inflammatory property to cope with renal tissue injury in kidney stone disease. Nevertheless, its direct effect (if any) on calcium oxalate (CaOx) crystals and the stone formation mechanism had not been previously explored. This study has addressed the ability of quercetin at various concentrations (2.5, 5, 10, 20, 40, 80 and 160 μM) to directly modulate CaOx crystallization, growth, aggregation, adhesion on kidney cells, and invasion through the matrix. The data have shown that quercetin significantly inhibits CaOx crystallization and crystal growth but promotes crystal aggregation in concentration-dependent manner. However, quercetin at all these concentrations do not affect CaOx adhesion on kidney cells. For the invasion, quercetin at all concentrations constantly promotes CaOx invasion through the matrix without concentration-dependent pattern. These discoveries have demonstrated for the first time that quercetin has direct but dual modulatory effects on CaOx crystals. While quercetin inhibits CaOx crystallization and growth, on the other hand, it promotes CaOx crystal aggregation and invasion through the matrix. These data highlight the role for quercetin in direct modulation of the CaOx crystals that may intervene the stone pathogenesis.

Metabolomic profiles and pathogenesis of nephrolithiasis

PURPOSE OF REVIEW

Kidney stone disease is caused by supersaturation of urine with certain metabolites and minerals. The urine composition of stone formers has been measured to prevent stone recurrence, specifically calcium, uric acid, oxalate, ammonia, citrate. However, these minerals and metabolites have proven to be unreliable in predicting stone recurrence. Metabolomics using high throughput technologies in well defined patient cohorts can identify metabolites that may provide insight into the pathogenesis of stones as well as offer possibilities in therapeutics.

RECENT FINDINGS

Techniques including 1H-NMR, and liquid chromatography paired with tandem mass spectroscopy have identified multiple possible metabolites involved in stone formation. Compared to formers of calcium oxalate stones, healthy controls had higher levels of hippuric acid as well as metabolites involved in caffeine metabolism. Both the gut and urine microbiome may contribute to the altered metabolome of stone formers.

SUMMARY

Although metabolomics has offered several potential metabolites that may be protective against or promote stone formation, the mechanisms behind these metabolomic profiles and their clinical significance requires further investigation.

Causal relationship in gut microbiota and upper urinary urolithiasis using Mendelian randomization

Background

Several reports in recent years have found an association between gut microbiota and upper urinary urolithiasis. However, the causal relationship between them remains to be clarified.

Methods

Genetic variation is used as a tool in Mendelian randomization for inference of whether exposure factors have a causal effect on disease outcomes. We selected summary statistics from a large genome-wide association study of the gut microbiome published by the MiBioGen consortium with a sample size of 18,340 as an exposure factor and upper urinary urolithiasis data from FinnGen GWAS with 4,969 calculi cases and 213,445 controls as a disease outcome. Then, a two-sample Mendelian randomization analysis was performed by applying inverse variance-weighted, MR-Egger, maximum likelihood, and weighted median. In addition, heterogeneity and horizontal pleiotropy were excluded by sensitivity analysis.

Results

IVW results confirmed that class Deltaproteobacteria (OR = 0.814, 95% CI: 0.666-0.995, P = 0.045), order NB1n (OR = 0.833, 95% CI: 0.737-0.940, P = 3.15 × 10^-3), family Clostridiaceae1 (OR = 0.729, 95% CI: 0.581-0.916, P = 6.61 × 10^-3), genus Barnesiella (OR = 0.695, 95% CI: 0.551-0.877, P = 2.20 × 10^-3), genus Clostridium sensu_stricto_1 (OR = 0.777, 95% CI: 0.612-0.986, P = 0.0380), genus Flavonifractor (OR = 0.711, 95% CI: 0.536-0.944, P = 0.0181), genus Hungatella (OR = 0.829, 95% CI: 0.690-0.995, P = 0.0444), and genus Oscillospira (OR = 0.758, 95% CI: 0.577-0.996, P = 0.0464) had a protective effect on upper urinary urolithiasis, while Eubacterium xylanophilum (OR =1.26, 95% CI: 1.010-1.566, P = 0.0423) had the opposite effect. Sensitivity analysis did not find outlier SNPs.

Conclusion

In summary, a causal relationship was found between several genera and upper urinary urolithiasis. However, we still need further randomized controlled trials to validate.

Renal Artery Thrombosis Leading to Renal Infarct in a Patient With Recurrent Nephrolithiasis

Renal infarction is a rare entity that presents similarly to other common renal conditions such as nephrolithiasis, which can often result in a missed or delayed diagnosis. As a result, a high degree of suspicion for this diagnosis is warranted in patients presenting with flank pain. We present a patient with recurrent nephrolithiasis who presented with flank pain. A subsequent workup revealed a renal infarct due to underlying renal artery thrombosis. We also explore if there was a possible mechanism between this event and his history of recurrent nephrolithiasis.