M1/M2-macrophage phenotypes regulate renal calcium oxalate crystal development

An Ultrasmall Self-Assembled Gallic-Acid-Based Natural Multifunctional Defense Networks for Therapeutic Application in Calcium Oxalate Nephropathies

Kidney stones, which have high prevalence and recurrence rates, often cause severe oxidative damage and inflammation. The ultrasmall hydrodynamic diameter of nanoparticles is crucial for their enrichment in the kidneys to exert biological activity. However, integrating crystallization inhibition and therapeutic functions into a single ultrasmall nanoparticle is challenging. A novel ultrasmall iron (Fe)-gallic acid (Ga) metal-phenolic networks (Fe-Ga MPNs) is developed for treating calcium oxalate (CaOx) nephropathies. These MPNs can specifically adsorb on the high-energy (1 ¯ 01 $\bar{1}01$ ) crystal face to inhibit the growth of CaOx monohydrate (COM), promoting the phase transition from highly toxic COM to low-risk CaOx dihydrate. Fe-Ga MPNs have broad-spectrum free radical scavenging abilities, reducing oxidative damage and inhibiting cell apoptosis. They exhibit sensitivity toward kidney damage, accumulating in injured renal tissue, reducing tubule injury and inflammation, improving tubule function, and inhibiting crystal formation. Fe-Ga MPNs also inhibit pro-inflammatory macrophage polarization and upregulate anti-inflammatory and highly phagocytic macrophage polarization. RNA sequencing analysis shows that Fe-Ga MPNs induce transcriptomic changes mainly involving immune regulation and citrate homeostasis pathways. In conclusion, the multifunctional nanonetwork Fe-Ga MPNs, with crystallization inhibition, antioxidant, and immune regulation properties, show great potential in treating CaOx nephropathies.

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.

The role of osteopontin in modulating macrophage phagocytosis of calcium oxalate crystals

In inflammation, osteopontin (OPN) acts as both a stone matrix component for calcium oxalate (CaOx) crystal formation and an inflammatory mediator. While previous studies have demonstrated the individual roles of OPN and macrophages (Mφ) in renal CaOx stone formation during inflammation, their interaction remains poorly understood. This study aimed to elucidate the role of OPN in modulating Mφ function during crystal formation, using an ex vivo model. Bone marrow-derived macrophages (BMDM) were isolated from eight-week-old male C57BL/6J wild-type and OPN knockout mice. BMDMs from OPN-positive (BMDMOPN+) and OPN-negative (BMDMOPN-) mice were co-cultured with fluorescently labeled CaOx monohydrate (COM) crystals for phagocytosis assays and analyzed using the IN Cell Analyzer 6000. We further performed real-time quantitative reverse transcription PCR and RNA sequencing to identify gene expression profiles and clarify the role of OPN in Mφ function. The assay analysis demonstrated that phagocytosis rates were significantly higher in BMDMOPN- than in BMDMOPN+. Inflammatory markers, such as IL-6, TNF, CD44, were upregulated following COM exposure, and IL-6 expression was significantly lower in BMDMOPN- than in BMDMOPN+. RNA sequencing revealed that BMDMOPN- exhibited a less pro-inflammatory and more anti-inflammatory phenotype (Csf2low, Irf5low, Itgaxlow, Csf1high, Cd163high), resembling M2-like Mφs. Further functional analysis indicated that OPN knockdown in Mφs increased the S100 family and CREB signaling, which enhanced the M2-like phenotype shift and phagosome formation. In conclusion, OPN plays a critical role in enhancing pro-inflammatory Mφ function, potentially limiting COM phagocytosis. Modulating OPN expression in circulating Mφs may represent a therapeutic approach for kidney stone disease.

Recent developments in the study of cellular inflammation in the papillae of stone formers

Kidney stone disease has long been thought to involve tissue inflammation, but direct evidence linking inflammation as a causative factor in human stone formation remains limited. This review focuses on studies in human stone formers, highlighting variation in stone former phenotypes. Histological and molecular studies of kidney tissues reveal increased immune cell density and gene expression changes in stone formers, with notable differences between calcium oxalate and brushite stone pathologies. Phenotyping stone formers by tissue mineralization patterns-such as Randall's plaque or ductal plugging-shows significant heterogeneity in tissue damage, and thus presumably also inflammation. Systemic markers, such as elevated serum C-reactive protein, suggest a link between active stone disease and inflammation, although relationships vary with age, gender, and comorbidities. Such systemic markers have not been studied well in stone formers separated by phenotype. These insights underline the importance of stratifying patients by stone type and tissue pathology to identify inflammation pathways specific to each phenotype. Such an approach may pave the way for targeted anti-inflammatory therapies to reduce recurrence in this heterogeneous disease.

Association between dietary niacin intake and kidney stones in American adults

The evidence regarding the relationship between dietary niacin intake and kidney stones is limited. This study aims to investigate the association of dietary niacin intake with the prevalence of kidney stones among adults in the United States. The present cross-sectional study used data from the National Health and Nutrition Examination Survey (NHANES) 2007-2018. Dietary niacin intake was obtained from the first 24-h dietary recalls. The history of kidney stones was assessed by a questionnaire. Weighted logistic regression, restricted cubic splines (RCS) and stratified analysis were used to evaluate the relationship between dietary niacin intake and the risk of kidney stones. A total of 28,508 participants were included. In the full adjusted model, an inverse relationship between dietary niacin intake and kidney stones was observed. Compared to individuals in the lowest dietary niacin intake group, those in the highest group had lower odds of developing kidney stones (OR = 0.78, 95% CI = 0.63-0.97). RCS analysis showed a L-shaped relationship between niacin intake and kidney stones (P for non-linearity = 0.047). Stratified analysis indicated that this inverse associations appeared to be stronger among participants aged blew 60 years (P for interaction < 0.05). This cross-sectional study indicated that dietary niacin intake was associated with a decreased risk of kidney stones in US adults, especially in individuals under 60 years of age. Our findings suggest that appropriate doses of niacin intake may reduce the risk of kidney stones. Further research is required to confirm our findings and clarify the casual relationship.

UHRF1 promotes calcium oxalate-induced renal fibrosis by renal lipid deposition via bridging AMPK dephosphorylation

BACKGROUND

Nephrolithiasis, a common urinary system disorder, exhibits high morbidity and recurrence rates, correlating with renal dysfunction and the increased risk of chronic kidney disease. Nonetheless, the precise role of disrupted cellular metabolism in renal injury induced by calcium oxalate (CaOx) crystal deposition is unclear. The purpose of this study is to investigate the involvement of the ubiquitin-like protein containing PHD and RING finger structural domain 1 (UHRF1) in CaOx-induced renal fibrosis and its impacts on cellular lipid metabolism.

METHODS

Various approaches, including snRNA-seq, transcriptome RNA-seq, immunohistochemistry, and western blot analyses, were employed to assess UHRF1 expression in kidneys of nephrolithiasis patients, hyperoxaluric mice, and CaOx-induced renal tubular epithelial cells. Subsequently, knockdown of UHRF1 in mice and cells corroborated its effect of UHRF1 on fibrosis, ectopic lipid deposition (ELD) and fatty acid oxidation (FAO). Rescue experiments using AICAR, ND-630 and Compound-C were performed in UHRF1-knockdown cells to explore the involvement of the AMPK pathway. Then we confirmed the bridging molecule and its regulatory pathway in vitro. Experimental results were finally confirmed using AICAR and chemically modified si-UHRF1 in vivo of hyperoxaluria mice model.

RESULTS

Mechanistically, UHRF1 was found to hinder the activation of the AMPK/ACC1 pathway during CaOx-induced renal fibrosis, which was mitigated by employing AICAR, an AMPK agonist. As a nuclear protein, UHRF1 facilitates nuclear translocation of AMPK and act as a molecular link targeting the protein phosphatase PP2A to dephosphorylate AMPK and inhibit its activity.

CONCLUSION

This study revealed that UHRF1 promotes CaOx -induced renal fibrosis by enhancing lipid accumulation and suppressing FAO via inhibiting the AMPK pathway. These findings underscore the feasible therapeutic implications of targeting UHRF1 to prevent renal fibrosis due to stones.

Metabolic Insights into Urinary Stone Formation: Evidence from Mendelian Randomization, Clinical, and in vivo Studies

Introduction

The global rise in urinary stone prevalence has become a significant health and economic challenge. Linked to metabolic disorders such as obesity and diabetes, urinary stones represent a complex systemic condition that requires a comprehensive understanding of metabolic profiles for effective management.

Methods

The methodological quality of this study was evaluated in accordance with the STROBE-MR checklist. Using genome-wide association study (GWAS) data for 1,091 blood and 1,172 urine metabolites, we conducted a two-sample Mendelian randomization (MR) analysis, validated by meta-analysis, to explore metabolic influences on stone formation. Multivariable and mediation MR analyses were performed to identify independent metabolite influences and their interaction with gut microbiota and metabolism-related genes. Clinical metabolomic analysis and further animal experiments substantiated our findings.

Results

Univariable MR identified 119 blood and 63 urine metabolites associated with urinary stones, with 16 blood and 2 urine metabolites showing robust associations post-correction. Notably, mannose and 3-aminoisobutyrate emerged as independent influencers of stone formation. Mediation MR suggested these metabolites as potential mediators in the gut microbiota's influence on stone formation. Clinical urine sample analysis indicates higher mannose levels in normal renal sides than stone sides. Animal studies confirmed mannose's protective role by reducing renal calcium oxalate crystal deposition.

Conclusion

Our study establishes causal links between specific metabolites and urinary stones, shedding light on the intricate biological mechanisms of stone formation. The discovery of mannose as a protective factor opens avenues for future research and clinical applications, offering promising directions for the prevention and treatment of stones.

Bioinformatics identifies key genes and potential therapeutic targets in the pathological mechanism of oxidative stress in Randall's plaque

Randall's plaque (RP) is recognized as a precursor lesion for kidney stones, with its formation and progression potentially linked to oxidative stress. Previous studies have provided limited insights into the underlying mechanisms of RP, failing to fully elucidate its molecular pathways. To investigate the relationship between oxidative stress and RP, we employed bioinformatics approaches to identify key genes, predict associated pathways and drug molecules, analyze variations in immune cell populations, and construct diagnostic models. We initially identified three differentially expressed genes related to oxidative stress: BFSP1, LONF1, and TAF1D. These genes and their co-expressed counterparts are enriched in pathways related to oxidative phosphorylation, cellular adhesion processes, steroid hormone biosynthesis, and autophagy. Furthermore, we observed significant differences in two types of immune cells across the study groups. Ultimately, predictions from drug molecular docking suggest that BFSP1 may serve as a promising therapeutic target for RP. We propose that the formation of RP mediated by oxidative stress could be associated with BFSP1, LONF1, TAF1D along with CD56dim natural killer cells and memory B cells. Thus far, BFSP1 emerges as a pivotal therapeutic target for RP development. These findings offer new perspectives on the mechanisms underlying the pathogenesis of RP.

Prolyl hydroxylase domain inhibitors prevent kidney crystal formation by suppressing inflammation

The early stages of kidney crystal formation involve inflammation and hypoxia-induced cell injury; however, the role of the hypoxic response in kidney crystal formation remains unclear. This study investigated the effects of a prolyl hydroxylase domain inhibitor (roxadustat) on renal calcium oxalate (CaOx) crystal formation through in vitro and in vivo approaches. In the in vitro experiment, murine renal tubular cells (RTCs) were exposed to varying roxadustat concentrations and CaOx crystals. CaOx monohydrate (COM) crystal adhesion was evaluated using fluorescent labels, whereas western blotting was used to examine protein expression. Quantitative real-time polymerase chain reaction was used to analyze gene expression changes. Macrophage responses were investigated by co-culturing them with RTCs treated with COM. In the in vivo experiment, C57BL/6J mice were injected with roxadustat or saline for 2 days, followed by glyoxylate for 6 days to induce renal crystal deposition. Biochemical measurements recorded plasma erythropoietin, urinary data, and pH levels. Roxadustat suppressed the adhesion of COM crystals to RTCs and the expression of proinflammatory genes, such as chemokine (C-C motif) ligand 2 (Ccl2) and secreted phosphoprotein 1 (Spp1). Roxadustat decreased the expression levels of Ccl2, tumor necrosis factor (Tnf), and interleukin 6 (Il6) in co-cultured macrophages. In the in vivo experiment, the amount of renal CaOx crystal deposits was significantly lower in the roxadustat-treated group than in the vehicle group. Roxadustat treatment decreased Ccl2, Tnf, and adheision G protein-coupled receptor E1 (Adgre1) expression in the kidneys. Roxadustat reduced kidney inflammation and CaOx crystal deposition, suggesting its potential as a therapeutic option for kidney stone prevention.

Exploring the molecular interactions between nephrolithiasis and carotid atherosclerosis: asporin as a potential biomarker

Increasing evidence suggested nephrolithiasis has a close linkage with carotid atherosclerosis (CAS), with Randall's plaque (RP) being a precursor to kidney stones. Our study aimed to examine the crosstalk genes and potential molecular mechanisms between RP and CAS. We obtained microarray data for RP and CAS from the Gene Expression Omnibus (GEO) and used weighted gene co-expression network analysis (WGCNA) and differential gene expression (DEG) analysis to identify shared genes. By integrating WGCNA and DEG analysis, Asporin (ASPN) was identified as the key gene connecting RP and CAS, with its diagnostic potential assessed via a receiver operating characteristic (ROC) curve. Immune infiltration studies showed a significant correlation between ASPN and various immune cells in RP and CAS. ASPN was found to be less expressed in RP and CAS tissues compared to normal tissues, as confirmed by immunohistochemistry (IHC) and quantitative reverse-transcription PCR (qRT-PCR). The rat model confirmed the human tissue findings. ASPN can elucidate the shared pathogenic mechanisms underlying the two conditions, including immune response and osteoblast differentiation.

Association between the systemic inflammation response index and kidney stones in US adults: a cross-sectional study based on NHANES 2007-2018

This study examined the relationship between the systemic inflammation response index (SIRI) and kidney stone occurrence in adults in the United States. It also evaluated its potential as a predictor of kidney stones. A total of 24,833 adult participants were included in the study using cross-sectional data from the 2007-2018 National Health and Nutrition Examination Survey (NHANES) database. A history of kidney stones was ascertained through the administration of a questionnaire, and SIRI values (calculated based on neutrophil, monocyte, and lymphocyte counts) were determined for each participant. Logistic regression models were employed to examine the relationship between SIRI and kidney stones while accounting for potential confounding variables such as gender, age, race, lifestyle, and history of chronic disease. Subgroup analyses were also conducted. A significant positive correlation was observed between SIRI and kidney stones. In the unadjusted model, elevated SIRI was significantly and positively associated with an increased risk of kidney stones (OR = 1.17). Analysis of SIRI quartiles demonstrated a gradual increase in the risk ratio of kidney stones with increasing SIRI levels, indicating a clear dose-response relationship. In particular, in the model adjusted for multiple confounding variables, the risk of developing kidney stones in the highest SIRI quartile was increased by 20% compared to the lowest SIRI quartile (OR = 1.20, P = 0.007). There is a significant positive correlation between SIRI and kidney stones. SIRI may predict kidney stone risk and highlight the systemic inflammatory state's substantial contribution to kidney stones' pathogenesis.

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.

The Role of the Gut Microbiome in Kidney Stone Disease

Microbiome dysbiosis is closely related to the etiology of kidney stone disease (KSD) and influences a multitude of pathways. Due to our knowledge gaps on this topic, it is still unclear if microbiome interventions can be translated to demonstrate clinical efficacy. Current evidence suggests that the enhancement of butyrate-producing pathways should be the next step for KSD research. While we are not yet at a point where we can make clinical recommendations for KSD, there are many simple dietary or supplement-based approaches that could be applied in the future for prophylaxis or treatment of KSD.

Mitochondrial dysfunction and NLRP3 inflammasome: key players in kidney stone formation

The mitochondrion serves as a critical intracellular organelle, engaging in essential roles in the regulation of energy production, oxidative stress management, calcium homeostasis, and apoptosis. One such disease that has been particularly associated with these functions is kidney stone disease (KSD), specifically calcium oxalate (CaOx). It is underpinned by oxidative stress and tissue inflammation. Recent studies have shed light on the vital involvement of mitochondrial dysfunction, the nucleotide-binding domain and leucine-rich repeat containing protein 3 (NLRP3) inflammasome, endoplasmic reticulum stress and subsequent cell death in CaOx crystal retention and aggregation. These processes are pivotal in the pathogenesis of kidney stone formation. This review focuses on the pivotal roles of mitochondria in renal cell functions and provides an overview of the intricate interconnectedness between mitochondrial dysfunction and NLRP3 inflammasome activation in the context of KSD. It is essential to recognise the utmost significance of gaining a comprehensive understanding of the mechanisms that safeguard mitochondrial function and regulate the NLRP3 inflammasome. Such knowledge carries significant scientific implications and opens up promising avenues for the development of innovative strategies to prevent the formation of kidney stones.

Potential safety implications of fatty acid-binding protein inhibition

Fatty acid-binding proteins (FABPs) are small intracellular proteins that regulate fatty acid metabolism, transport, and signalling. There are ten known human isoforms, many of which are upregulated and involved in clinical pathologies. As such, FABP inhibition may be beneficial in disease states such as cancer, and those involving the cardiovascular system, metabolism, immunity, and cognition. Recently, a potent, selective FABP5 inhibitor (ART26.12), with 90-fold selectivity to FABP3 and 20-fold selectivity to FABP7, was found to be remarkably benign, with a no-observed-adverse-effect level of 1000 mg/kg in rats and dogs, showing no genotoxicity, cardiovascular, central, or respiratory toxicity. To understand the potential implication of FABP inhibition more fully, this review systematically assessed literature investigating genetic knockout, knockdown, and pharmacological inhibition of FABP3, FABP4, FABP5, or FABP7. Analysis of the literature revealed that animals bred not to express FABPs showed the most biological effects, suggesting key roles of these proteins during development. FABP ablation sometimes exacerbated symptoms of disease models, particularly those linked to metabolism, inflammatory and immune responses, cardiac contractility, neurogenesis, and cognition. However, FABP inhibition (genetic silencing or pharmacological) had a positive effect in many more disease conditions. Several polymorphisms of each FABP gene have also been linked to pathological conditions, but it was unclear how several polymorphisms affected protein function. Overall, analysis of the literature to date suggests that pharmacological inhibition of FABPs in adults is of low risk.

Macrophage polarization regulation shed lights on immunotherapy for CaOx kidney stone disease

Kidney stone disease (KSD) is a major public health concern associated with high morbidity and recurrence, places a significant burden on the health care system worldwide. Calcium oxalate (CaOx) alone or a mixture of CaOx and calcium phosphate stones accounting for more than 80 % of cases. However, beyond surgical removal, the prevention and reduction of recurrence of CaOx kidney stones have always been a challenge. Given that macrophages are traditional innate immune cells that play critical roles in the clearance of pathogens and the maintenance of tissue homeostasis, which have gained more and more interests in nephrolithiasis. Several studies recently clearly demonstrated that M2-macrophage could reduce the renal calcium oxalate (CaOx) crystal acumination, and provide premise insights and therapeutic options for KSD by modulating the macrophage phenotypes. However, the mechanism of macrophage-polarization regulation and that effects on kidney stone prevention and treatments are far from clear. Here, we comprehensively reviewed the literatures related to cytokines, epigenetic modifications and metabolic reprograming of macrophage in CaOx kidney stone disease, aimed to provide better understandings on macrophage polarization regulation as well as its potential clinical applications in CaOx kidney stone disease treatments and prevention.

The identification of key molecules and pathways in the crosstalk of calcium oxalate-treated TCMK-1 cells and macrophage via exosomes

The interplay between crystals and epithelial cells forms the cornerstone of kidney stone development, communication between epithelial cells and macrophages emerging as a pivotal role in this process. We conducted next-generation sequencing on the secreted exosomes of TCMK-1 cells treated with calcium oxalate monohydrate (OX_EXO) or controls (NC_EXO), and on the macrophage cell line RAW264.7 stimulated with OX_EXO or NC_EXO, followed by validation of differentially expressed target proteins and miRNAs through Western blot and PCR. UPSET plots were employed to identify genes co-targeted by exosomal miRNAs. Various bioinformatic analyses were employed to predict potential mechanisms of the dysregulated genes. We integrated sequencing data from the GEO database, and validated findings using clinical patient urine and kidney tissues. We identified 665 differentially expressed exosomal miRNAs between OX_EXO and NC_EXO. Among the top 10 down-regulated miRNAs, the most targeted genes were AAK1 and NUFIP2, whereas PLCB1 was significantly targeted among the top 10 up-regulated miRNAs. In clinical specimens, we confirmed the differential expressions of five homologous miRNAs, as well as CNOT3, CNCNA1C, APEX1, and TMEM199. In conclusion, treatment of TCMK-1 cells with calcium oxalate significantly alerted the expression profile of exosomal miRNAs, subsequently influencing gene expression in macrophages, thereby modulating the processes of kidney stone formation.

Expression Profiles of Claudin Gene Family Members in Patients With Recurrent Calcium Oxalate Kidney Stones

INTRODUCTION

In this study, we aimed to evaluate and compare the expression profiles of CLDN gene family members responsible for the mechanism of stone formation in patients with recurrent calcium oxalate stones and in a control group without a history of renal stones.

METHODS

Nineteen patients with recurrent calcium oxalate renal calculi who underwent percutaneous nephrolithotomy and 21 control patients without renal calculi who underwent surgery for other reasons were included in the study. The urinary calcium, oxalate, and citrate levels of the patients included in the study, as well as those in the control group, were within normal ranges. They did not have proteinuria in their urine. The biochemical parameters were also within normal limits. Biopsy samples taken from the intact renal cortex parenchymal tissue were consistent. Total RNA was isolated from biopsy samples and expression profiles of target genes (Claudin 1-4, 7, 8, 10, 14, 16, 18, 19) were determined by real-time polymerase chain reaction (PCR).

RESULTS

It was determined that CLDN1 gene expression in patients with recurrent calcium oxalate kidney stones was approximately four times higher than in the control group; this difference was statistically significant (p<0.050). CLDN1 expression was also strongly positively correlated with CLDN4 (r=0.642), CLDN7 (r=0.753) and CLDN14 (r=0.651) Conclusions: We thought that CLDN1 overexpression might play a role in the pathogenesis of recurrent calcium oxalate stone formation. CLDN1 together with CLDN2, CLDN4, CLDN7, and CLDN14 are also probably responsible for this pathogenesis.

Immune-inflammatory process in nephrolithiasis: A bibliometric analysis (2000-2023)

The research on the mechanism of nephrolithiasis formation is of great importance due to the fact that the high incidence and recurrence rate of nephrolithiasis bring considerable economic burdens to patients and society. As an important component in the nephrolithiasis formation process, the immune-inflammatory process has been gradually valued by researchers in recent years. In this study, articles related to the immune-inflammatory process of nephrolithiasis published since 2000 were retrieved based on the Web of Science (WoS) database. Eventually, a total of 370 articles were selected for subsequent analyses. Besides, VOSviewer, CiteSpace, and Bibliometrix were employed to quantitatively analyze and visualize the data. The number of articles related to the immune-inflammatory process of nephrolithiasis has increased rapidly in the last five years. From the country level, most articles were contributed by China (n = 140) and the United States (n = 99) contributed the most documents. From the institution level, University of Florida (n = 36) and Nagoya City University (n = 21) had the most articles. From the journal level, Journal of Urology and Urolithiasis published the most articles in this field. Keywords mainly included inflammation, oxidative stress, calcium oxalate, osteopontin, and hyperoxaluria, which represented the research directions in this field. The most productive author was Khan SR (n = 33), whose articles obtained the highest number of citations (2086 times). These efforts may help researchers understand the current progress and status of research on the immune-inflammatory process of nephrolithiasis and identify future research hotspots and directions.

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.

The immune factors have complex causal regulation effects on kidney stone disease: a mendelian randomization study

PURPOSE

Previous studies have reported the potential impact of immune cells on kidney stone disease (KSD), but definitive causal relationships have yet to be established. The purpose of this paper is to elucidate the potential causal association between immune cells and KSD by Mendelian randomization (MR) analysis.

METHODS

In our study, a thorough two-sample Mendelian randomization (MR) analysis was performed by us to determine the potential causal relationship between immune cell traits and kidney stone disease. We included a total of four immune traits (median fluorescence intensity (MFI), relative cellular (RC), absolute cellular (AC), and morphological parameters (MP)), which are publicly available data. GWAS summary data related to KSD (9713 cases and 366,693 controls) were obtained from the FinnGen consortium. The primary MR analysis method was Inverse variance weighted. Cochran's Q test, MR Egger, and MR-Pleiotropy RESidual Sum and Outlier (MR-PRESSO) were used to assess the stability of the results.

RESULTS

After FDR correction, the CD8 on HLA DR + CD8br (OR = 0.95, 95% CI = 0.93-0.98, p-value = 7.20 × 10- 4, q-value = 0.088) was determined to be distinctly associated with KSD, and we also found other 25 suggestive associations between immune cells and KSD, of which 13 associations were suggested as protective factors and 12 associations were suggested as risk factors. There was no horizontal pleiotropy or significant heterogeneity in our MR analysis, as determined by the p-value results of our Cochrane Q-test, MR Egger's intercept test, and MR-PRESSO, which were all > 0.05.

CONCLUSIONS

Our study has explored the potential causal connection between immune cells and KSD by Mendelian randomization analysis, thus providing some insights for future clinical studies.

CCR2 antagonist attenuates calcium oxalate-induced kidney oxidative stress and inflammation by regulating macrophage activation

C-C chemokine receptor type 2 (CCR2) is a monocyte chemokine associated with oxidative stress and inflammation. Kidney stones (KS) are composed of calcium oxalate (CaOx), which trigger renal oxidative stress and inflammatory. This study aims to evaluate the effects of CCR2 on KS in vivo and in vitro. Eight-week-old male C57BL/6J mice were intraperitoneally injected with glyoxylate (GOX) daily to establish a KS model, and along with CCR2 antagonist (INCB3344) treatment on days 2, 4, and 6. The results showed that CCR2 antagonist reduced renal injury markers (blood urea nitrogen and serum creatinine), alleviated renal tubular injury and CaOx crystal deposition. CCR2 antagonist also decreased CCR2 expression induced by GOX treatment and increased Nrf2 expression. GOX treatment promoted malondialdehyde (MDA) production, decreased glutathione (GSH) content, and inhibited catalase (CAT) and superoxide dismutase (SOD) activity, however, CCR2 antagonist attenuated the above effects of GOX. CCR2 antagonist had inhibitory effects on GOX-induced inflammatory cytokine expression (IL1B, IL6 and MCP1), and inhibited apoptosis by increasing Bcl-2 expression and decreasing Bax and cleaved-caspase 3 expression. In vitro experiments were performed by co-culture model of CaOx-induced damaged HK-2 cells and macrophage-like THP-1 cells. CCR2 antagonist inhibited CaOx-induced THP-1 cell M1 polarization by decreasing the TNF-α, IL6 and iNOS levels, and further alleviated CaOx-induced oxidative stress damage, inflammatory response and apoptosis of HK-2 cells. The study suggests that CCR2 antagonist may be resistant to CaOx crystals-induced oxidative stress and inflammation by inhibiting macrophage M1 polarization.

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.

Associations between the platelet/high-density lipoprotein cholesterol ratio and likelihood of nephrolithiasis: a cross-sectional analysis in United States adults

Aims

The primary objective of this study was to investigate the relationship between the platelet/high-density lipoprotein cholesterol ratio (PHR) and the prevalence of nephrolithiasis within the adult population of the United States.

Methods

The data used in this study were obtained from the National Health and Nutrition Examination Survey (NHANES) conducted between 2007 and 2018. The analysis included a non-pregnant population aged 20 years or older, providing proper PHR index and nephrolithiasis data. The research utilized subgroup analyses and weighted univariate and multivariable logistic regression to evaluate the independent association between the PHR and the susceptibility to nephrolithiasis.

Results

The study comprised 30,899 participants with an average PHR value of 19.30 ± 0.11. The overall prevalence rate of nephrolithiasis was estimated at 9.98% with an increase in the higher PHR tertiles (T1, 8.49%; T2, 10.11%; T3, 11.38%, P < 0.0001). An elevated PHR level was closely linked with a higher susceptibility to nephrolithiasis. Compared with patients in T1, and after adjusting for potential confounders in model 2, the corresponding odds ratio for nephrolithiasis in T3 was 1.48 (95% CI: 1.06 to 2.08), with a P-value = 0.02. The results of the interaction tests revealed a significant impact of chronic kidney disease on the relationship between PHR and nephrolithiasis. Furthermore, the restricted cubic spline analyses exhibited a positive, non-linear correlation between PHR and the risk of nephrolithiasis.

Conclusion

A convenient biomarker, the PHR, was independently associated with nephrolithiasis and could be a novel biomarker in predicting occurrence in clinical decision.

Mrc1+ macrophage-derived IGF1 mitigates crystal nephropathy by promoting renal tubule cell proliferation via the AKT/Rb signaling pathway

Rationale: The present understanding of the cellular characteristics and communications in crystal nephropathy is limited. Here, molecular and cellular studies combined with single-cell RNA sequencing (scRNA-seq) were performed to investigate the changes in cell components and their interactions in glyoxylate-induced crystallized kidneys to provide promising treatments for crystal nephropathy. Methods: The transcriptomes of single cells from mouse kidneys treated with glyoxylate for 0, 1, 4, or 7 days were analyzed via 10× Genomics, and the single cells were clustered and characterized by the Seurat pipeline. The potential cellular interactions between specific cell types were explored by CellChat. Molecular and cellular findings related to macrophage-to-epithelium crosstalk were validated in sodium oxalate (NaOx)-induced renal tubular epithelial cell injury in vitro and in glyoxylate-induced crystal nephropathy in vivo. Results: Our established scRNA atlas of glyoxylate-induced crystalline nephropathy contained 15 cell populations with more than 40000 single cells, including relatively stable tubular cells of different segments, proliferating and injured proximal tubular cells, T cells, B cells, and myeloid and mesenchymal cells. In this study, we found that Mrc1+ macrophages, as a subtype of myeloid cells, increased in both the number and percentage within the myeloid population as crystal-induced injury progresses, and distinctly express IGF1, which induces the activation of a signal pathway to dominate a significant information flow towards injured and proliferating tubule cells. IGF1 promoted the repair of damaged tubular epithelial cells induced by NaOx in vitro, as well as the repair of damaged tubular epithelial cells and the recovery of disease outcomes in glyoxylate-induced nephrolithic mice in vivo. Conclusion: After constructing a cellular atlas of glyoxylate-induced crystal nephropathy, we found that IGF1 derived from Mrc1+ macrophages attenuated crystal nephropathy through promoting renal tubule cell proliferation via the AKT/Rb signaling pathway. These findings could lead to the identification of potential therapeutic targets for the treatment of crystal nephropathy.

The association between C-reactive protein levels and the risk of kidney stones: a population-based study

OBJECTIVES

The relationship between C-reactive protein (CRP) and the risk of developing kidney stones is unclear, and we aimed to assess the association between CRP and kidney stones in US adults.

METHODS

We used data from NHANES 2007-2010, and we excluded participants who were under 18 years of age and lacked data on CRP and kidney stones. Finally, we included a total of 11,033 participants and performed weighted multivariate regression analysis and subgroup analysis to assess the independent relationship between CRP and kidney stones.

RESULTS

The mean prevalence of kidney stones among the participants was 9.8%. Notably, as CRP levels increased, the prevalence of kidney stones exhibited a corresponding rise across quartiles (Kidney stones: Quartile 1: 7.59%; Quartile 2: 8.77%; Quartile 3: 9.64%; Quartile 4: 10.89%). CRP was positively associated with the risk of kidney stones (Model 1: OR = 1.09, 95% CI: 1.01-1.18, p = 0.03; Model 2: OR = 1.09, 95% CI: 1.00-1.18, p = 0.03, Model 3: OR = 1.14, 95%CI: 1.02-1.26, p = 0.04). Participants in the highest CRP quartile experienced a 69% increased risk of kidney stones compared to those in the lowest quartile (OR = 1.64, 95% CI: 1.04-2.59, p = 0.03). Notably, interaction tests revealed that gender, BMI, diabetes, hypertension, CKD and smoking or alcohol consumption status did not significantly influence the association between CRP and kidney stones.

CONCLUSIONS

Our findings reveal a significant association between higher CRP levels and an increased risk of kidney stones. In clinical practice, heightened awareness of CRP as a potential biomarker could aid in risk assessment and management strategies for kidney stone patients.

Sirtuin1 inhibits calcium oxalate crystal-induced kidney injury by regulating TLR4 signaling and macrophage-mediated inflammatory activation

Sirtuin1 (Sirt1) activation significantly attenuated calcium oxalate (CaOx) crystal deposition and renal inflammatory injury by regulating renal immune microenvironment. Here, to elucidate the molecular mechanism underlying the therapeutic effects of Sirt1 on macrophage related inflammation and tubular epithelial cells (TECs) necrosis, we constructed a macrophage and CaOx monohydrate (COM)-stimulated tubular cell co-culture system to mimic immune microenvironment in kidney and established a mouse model of CaOx nephrocalcinosis in wild-type and myeloid-specific Sirt1 knockout mice. Target prediction analyses of Gene Expression Omnibus Datasets showed that only miR-34b-5p is regulated by lipopolysaccharides and upregulated by SRT1720 and targets the TLR4 3'-untranslated region. In vitro, SRT1720 suppressed TLR4 expression and M1 macrophage polarization and decreased reactive oxygen species (ROS) production and mitochondrial damage in COM-stimulated TECs by targeting miR-34b-5p. Mechanically, Sirt1 promoted miR-34b-5p expression by suppressing the tri-methylation of H3K27, which directly bound to the miR-34b-5p promoter and abolished the miR-34b-5p transcription. Furthermore, loss of Sirt1 aggravated CaOx nephrocalcinosis-induced inflammatory and oxidative kidney injury, while AgomiR-34b reversed these effects. Therefore, our data suggested that Sirt1 inhibited TLR4 signaling and M1 macrophage polarization and decreased inflammatory and oxidative injury of TECs in vitro and in vivo.

Inflammation-associated ectopic mineralization

Ectopic mineralization refers to the deposition of mineralized complexes in the extracellular matrix of soft tissues. Calcific aortic valve disease, vascular calcification, gallstones, kidney stones, and abnormal mineralization in arthritis are common examples of ectopic mineralization. They are debilitating diseases and exhibit excess mortality, disability, and morbidity, which impose on patients with limited social or financial resources. Recent recognition that inflammation plays an important role in ectopic mineralization has attracted the attention of scientists from different research fields. In the present review, we summarize the origin of inflammation in ectopic mineralization and different channels whereby inflammation drives the initiation and progression of ectopic mineralization. The current knowledge of inflammatory milieu in pathological mineralization is reviewed, including how immune cells, pro-inflammatory mediators, and osteogenic signaling pathways induce the osteogenic transition of connective tissue cells, providing nucleating sites and assembly of aberrant minerals. Advances in the understanding of the underlying mechanisms involved in inflammatory-mediated ectopic mineralization enable novel strategies to be developed that may lead to the resolution of these enervating conditions.

Oxalate disrupts monocyte and macrophage cellular function via Interleukin-10 and mitochondrial reactive oxygen species (ROS) signaling

Oxalate is a small compound found in certain plant-derived foods and is a major component of calcium oxalate (CaOx) kidney stones. Individuals that consume oxalate enriched meals have an increased risk of forming urinary crystals, which are precursors to CaOx kidney stones. We previously reported that a single dietary oxalate load induces nanocrystalluria and reduces monocyte cellular bioenergetics in healthy adults. The purpose of this study was to extend these investigations to identify specific oxalate-mediated mechanisms in monocytes and macrophages. We performed RNA-Sequencing analysis on monocytes isolated from healthy subjects exposed to a high oxalate (8 mmol) dietary load. RNA-sequencing revealed 1,198 genes were altered and Ingenuity Pathway Analysis demonstrated modifications in several pathways including Interleukin-10 (IL-10) anti-inflammatory cytokine signaling, mitochondrial metabolism and function, oxalic acid downstream signaling, and autophagy. Based on these findings, we hypothesized that oxalate induces mitochondrial and lysosomal dysfunction in monocytes and macrophages via IL-10 and reactive oxygen species (ROS) signaling which can be reversed with exogenous IL-10 or Mitoquinone (MitoQ; a mitochondrial targeted antioxidant). We exposed monocytes and macrophages to oxalate in an in-vitro setting which caused oxidative stress, a decline in IL-10 cytokine levels, mitochondrial and lysosomal dysfunction, and impaired autophagy in both cell types. Administration of exogenous IL-10 and MitoQ attenuated these responses. These findings suggest that oxalate impairs metabolism and immune response via IL-10 signaling and mitochondrial ROS generation in both monocytes and macrophages which can be potentially limited or reversed. Future studies will examine the benefits of these therapies on CaOx crystal formation and growth in vivo.

The genetics of urinary microbiome, an exploration of the trigger in calcium oxalate stone

Background: Kidney stone disease is a global disease; however, it has not been totally understood. Calcium oxalate (CaOx) stone is the dominant type of kidney stone, and the potential factors involved in its formation are yet to be explored. Clinically, we found that the CaOx stones in patients were mainly unilateral; therefore, systemic factors cannot explain them, although some local factors must be involved. Urinary microbiota is involved in stone formation. Therefore, this study aimed to explore the association between the urinary microbiota and CaOx stones and provide insight into the medical treatment and prevention of CaOx stones. Methods: Sixteen pelvic urine samples were collected from the stone and non-stone sides of patients with unilateral CaOx stones following strict criteria. The 16S rRNA gene sequencing was performed on each pair of pelvic urine samples at the species level. Many bioinformatic analyses were conducted to explore the potential factors affecting CaOx stone formation. Results: Although no statistically significant difference was found between the overall microbiota of the pelvis urine from the two sides. Many biologically distinct taxa were observed, including many bacteria found in previous studies, like Proteobacteria, Actinobacteria, Firmicute and Enterobacter cloacae and so on. What's more, despite these common bacteria, our current study added to these bacterial communities with additional identification of Deinococcus-Thermus, Coriobacteriia, Porphyromonas and Ralstonia. To predict the functions of these microbiota, Kyoto Encyclopedia for Genes and Genomes and MetaCyc analysis were conducted and immunometabolism might be an important pathway. Moreover, a random forest predictor was constructed to distinguish the stone side from the non-stone side, with an accuracy of 62.5%. Conclusion: Our research profiled the microbiome in the pelvis urine from both the stone and non-stone sides of patients with unilateral CaOx stones, provided insight into the dominant role of urinary dysbiosis in CaOx stones formation. Furthermore, this study also predicted the potential crosstalk among urinary microbiota, immunometabolism, and CaOx stones.

A spatially anchored transcriptomic atlas of the human kidney papilla identifies significant immune injury in patients with stone disease

Kidney stone disease causes significant morbidity and increases health care utilization. In this work, we decipher the cellular and molecular niche of the human renal papilla in patients with calcium oxalate (CaOx) stone disease and healthy subjects. In addition to identifying cell types important in papillary physiology, we characterize collecting duct cell subtypes and an undifferentiated epithelial cell type that was more prevalent in stone patients. Despite the focal nature of mineral deposition in nephrolithiasis, we uncover a global injury signature characterized by immune activation, oxidative stress and extracellular matrix remodeling. We also identify the association of MMP7 and MMP9 expression with stone disease and mineral deposition, respectively. MMP7 and MMP9 are significantly increased in the urine of patients with CaOx stone disease, and their levels correlate with disease activity. Our results define the spatial molecular landscape and specific pathways contributing to stone-mediated injury in the human papilla and identify associated urinary biomarkers.

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

Objective

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

Methods

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

Results

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

Conclusion

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

Metabolic changes in kidney stone disease

Kidney stone disease (KSD) is one of the earliest medical diseases known, but the mechanism of its formation and metabolic changes remain unclear. The formation of kidney stones is a extensive and complicated process, which is regulated by metabolic changes in various substances. In this manuscript, we summarized the progress of research on metabolic changes in kidney stone disease and discuss the valuable role of some new potential targets. We reviewed the influence of metabolism of some common substances on stone formation, such as the regulation of oxalate, the release of reactive oxygen species (ROS), macrophage polarization, the levels of hormones, and the alternation of other substances. New insights into changes in substance metabolism changes in kidney stone disease, as well as emerging research techniques, will provide new directions in the treatment of stones. Reviewing the great progress that has been made in this field will help to improve the understanding by urologists, nephrologists, and health care providers of the metabolic changes in kidney stone disease, and contribute to explore new metabolic targets for clinical therapy.

Bioinformatics analysis reveals the potential role of matrix metalloproteinases in immunity and urolithiasis

Background

The pathogenesis of urolithiasis remains unclear, making the development of medications for treatment and prevention stagnant. Randall’s plaques (RPs) begin as interstitial calcium phosphate crystal deposits, grow outward and breach the renal papillary surface, acting as attachment for CaOx stones. Since matrix metalloproteinases (MMPs) can degrade all components of extracellular matrix (ECM), they might participate in the breach of RPs. Besides, MMPs can modulate the immune response and inflammation, which were confirmed to be involved in urolithiasis. We aimed to investigate the role of MMPs in the development of RPs and stone formation.

Methods

The public dataset GSE73680 was mined to identify differentially expressed MMPs (DEMMPs) between normal tissues and RPs. WGCNA and three machine learning algorithms were performed to screen the hub DEMMPs. In vitro experiments were conducted for validation. Afterwards, RPs samples were classified into clusters based on the hub DEMMPs expression. Differentially expressed genes (DEGs) between clusters were identified and functional enrichment analysis and GSEA were applied to explore the biological role of DEGs. Moreover, the immune infiltration levels between clusters were evaluated by CIBERSORT and ssGSEA.

Results

Five DEMMPs, including MMP1, MMP3, MMP9, MMP10, and MMP12, were identified between normal tissues and RPs, and all of them were elevated in RPs. Based on WGCNA and three machine learning algorithms, all of five DEMMPs were regarded as hub DEMMPs. In vitro validation found the expression of hub DEMMPs also increased in renal tubular epithelial cells under lithogenic environment. RPs samples were divided into two clusters and cluster A exhibited higher expression of hub DEMMPs compared to cluster B. Functional enrichment analysis and GSEA found DEGs were enriched in immune-related functions and pathways. Moreover, increased infiltration of M1 macrophages and enhanced levels of inflammation were observed in cluster A by immune infiltration analysis.

Conclusion

We assumed that MMPs might participate in RPs and stone formation through ECM degradation and macrophages-mediated immune response and inflammation. Our findings offer a novel perspective on the role of MMPs in immunity and urolithiasis for the first time, and provide potential biomarkers to develop targets for treatment and prevention.

Identification of the core genes in Randall's plaque of kidney stone and immune infiltration with WGCNA network

Background: Randall's plaque is regarded as the precursor lesion of lithiasis. However, traditional bioinformatic analysis is limited and ignores the relationship with immune response. To investigate the underlying calculi formation mechanism, we introduced innovative algorithms to expand our understanding of kidney stone disease. Methods: We downloaded the GSE73680 series matrix from the Gene Expression Omnibus (GEO) related to CaOx formation and excluded one patient, GSE116860. In the RStudio (R version 4.1.1) platform, the differentially expressed genes (DEGs) were identified with the limma package for GO/KEGG/GSEA analysis in the clusterProfiler package. Furthermore, high-correlated gene co-expression modules were confirmed by the WGCNA package to establish a protein-protein interaction (PPI) network. Finally, the CaOx samples were processed by the CIBERSORT algorithm to anchor the key immune cells group and verified in the validation series matrix GSE117518. Results: The study identified 840 upregulated and 1065 downregulated genes. The GO/KEGG results revealed fiber-related or adhesion-related terms and several pathways in addition to various diseases identified from the DO analysis. Moreover, WGCNA selected highly correlated modules to construct a PPI network. Finally, 16 types of immune cells are thought to participate in urolithiasis pathology and are related to hub genes in the PPI network that are proven significant in the validation series matrix GSE117518. Conclusion: Randall's plaque may relate to genes DCN, LUM, and P4HA2 and M2 macrophages and resting mast immune cells. These findings could serve as potential biomarkers and provide new research directions.

Renal tubular epithelial cells treated with calcium oxalate up-regulate S100A8 and S100A9 expression in M1-polarized macrophages via interleukin 6

Objectives

Calgranulins S100A8 and S100A9 are common in renal stones and they are up-regulated in both urinary exosomes and kidneys of stone patients. Renal sources and important regulators for S100A8 and S100A9 in nephrolithiasis were explored in this study.

Materials and Methods

We identified S100A8 and S100A9 abundance in various renal cells by searching the Single Cell Type Atlas. Macrophages were polarized from human myeloid leukemia mononuclear cells. Human proximal renal tubular epithelial cells (HK-2) were stimulated with calcium oxalate monohydrate (COM). Coculture experiments involving HK-2 cells and macrophages were conducted. qPCR, Western blotting, ELISA, and immunofluorescence were used for detecting interleukin 6 (IL6), S100A8, and S100A9.

Results

The Single Cell Type Atlas showed that S100A8 and S100A9 in human kidneys primarily originated from macrophages. M1 was the predominant macrophage type expressing S100A8 and S100A9. Direct culture with COM did not affect the expression of these two calgranulins in M1 macrophages but coculture with COM-treated HK-2 cells did. COM could promote HK-2 cells to secrete IL6. IL6 could up-regulate S100A8 and S100A9 expression in macrophages of M1 type. In addition, 0.5 μM SC144 (a kind of IL6 inhibitor) significantly prevented COM-treated HK-2 cells from up-regulating S100A8 and S100A9 expression in macrophages of M1 type.

Conclusion

M1-polarized macrophages were the predominant cell type expressing S100A8 and S100A9 in the kidneys of nephrolithiasis patients. CaOx crystals can promote renal tubular epithelial cells to secrete IL6 to up-regulate S100A8 and S100A9 expression in macrophages of M1 type.

Association between the systemic immune-inflammation index and kidney stone: A cross-sectional study of NHANES 2007-2018

Background

The incidence rate of kidney stones increased over the past decades globally, which brought medical expenditure and social burden. The systemic immune-inflammatory index (SII) was initially identified as a prognosis of multiple diseases. We performed an updated analysis on the impact of SII on kidney stones.

Methods

This compensatory cross-sectional study enrolled participants from the National Health and Nutrition Examination Survey 2007-2018. Univariate and multivariate logistic regression analyses were performed to investigate the association between SII and kidney stones.

Results

Of the 22220 participants, the mean (SD) age was 49.45 ± 17.36 years old, with a 9.87% incidence rate of kidney stones. A fully adjusted model showed that SII higher than 330 x 10⁹/L was parallel associated with kidney stones (Odds ratio [OR] = 1.282, 95% Confidence interval [CI] = 1.023 to 1.608, P = 0.034) in adults aged 20-50. However, no difference was found in the elderly subgroup. Multiple imputation analyses confirmed the robustness of our results.

Conclusions

Our findings suggested SII was positively associated with a high risk of kidney stones in US adults aged less than 50. The outcome compensated for previous studies that still needed more large-scale prospective cohorts for validation.

Development of Cell Therapies for Renal Disease and Regenerative Medicine

The incidence of renal disease is gradually increasing worldwide, and this condition has become a major public health problem because it is a trigger for many other chronic diseases. Cell therapies using multipotent mesenchymal stromal cells, hematopoietic stem cells, macrophages, and other cell types have been used to induce regeneration and provide a cure for acute and chronic kidney disease in experimental models. This review describes the advances in cell therapy protocols applied to acute and chronic kidney injuries and the attempts to apply these treatments in a clinical setting.

Osteopontin: An important protein in the formation of kidney stones

The incidence of kidney stones averages 10%, and the recurrence rate of kidney stones is approximately 10% at 1 year, 35% at 5 years, 50% at 10 years, and 75% at 20 years. However, there is currently a lack of good medicines for the prevention and treatment of kidney stones. Osteopontin (OPN) is an important protein in kidney stone formation, but its role is controversial, with some studies suggesting that it inhibits stone formation, while other studies suggest that it can promote stone formation. OPN is a highly phosphorylated protein, and with the deepening of research, there is growing evidence that it promotes stone formation, and the phosphorylated protein is believed to have adhesion effect, promote stone aggregation and nucleation. In addition, OPN is closely related to immune cell infiltration, such as OPN as a pro-inflammatory factor, which can activate mast cells (degranulate to release various inflammatory factors), macrophages (differentiated into M1 macrophages), and T cells (differentiated into T1 cells) etc., and these inflammatory cells play a role in kidney damage and stone formation. In short, OPN mainly exists in the phosphorylated form in kidney stones, plays an important role in the formation of stones, and may be an important target for drug therapy of kidney stones.

Risks of Carotid Artery Stenosis and Atherosclerotic Cardiovascular Disease in Patients with Calcium Kidney Stone: Assessment of Systemic Inflammatory Biomarkers

(1) Background: To assess the clinical significance of preoperative inflammatory biomarkers combined with atherosclerotic cardiovascular disease (ASCVD) risk score to evaluate carotid artery stenosis in patients with calcium kidney stones; (2) Methods: We conducted a prospective observational case-control study, enrolling 74 patients with calcium kidney stones and 66 age- and sex-matched healthy controls. We calculated the inflammatory biomarkers including the neutrophil-lymphocyte ratio (NLR), monocyte-lymphocyte ratio (MLR), and systemic inflammation response index (SIRI). An ultrasound of the carotid arteries was performed on all participants to identify the severity of the stenosis; (3) Results: All inflammatory biomarkers and the severity of carotid artery stenosis were higher in the calcium kidney stone group than in controls. After stratification of ASCVD, inflammatory biomarkers and carotid artery stenosis severity were still significantly higher in the calcium kidney stone group. Multivariate analyses showed that calcium kidney stones significantly increased the risk of ASCVD and carotid artery stenosis. In multivariate linear logistic regression analyses, calcium kidney stone and ASCVD score had a significant association with carotid artery occlusion, but SIRI did not; (4) Conclusions: Calcium kidney stone is associated with higher levels of inflammatory biomarkers and carotid artery stenosis. Calcium kidney stone is associated with higher levels of inflammatory biomarkers and carotid artery stenosis.

Critical Role of Osteopontin in Maintaining Urinary Phosphate Solubility in CKD

Background

Nephron loss dramatically increases tubular phosphate to concentrations that exceed supersaturation. Osteopontin (OPN) is a matricellular protein that enhances mineral solubility in solution; however, the role of OPN in maintaining urinary phosphate solubility in CKD remains undefined.

Methods

Here, we examined (1) the expression patterns and timing of kidney/urine OPN changes in CKD mice, (2) if tubular injury is necessary for kidney OPN expression in CKD, (3) how OPN deletion alters kidney mineral deposition in CKD mice, (4) how neutralization of the mineral-binding (ASARM) motif of OPN alters kidney mineral deposition in phosphaturic mice, and (5) the in vitro effect of phosphate-based nanocrystals on tubular epithelial cell OPN expression.

Results

Tubular OPN expression was dramatically increased in all studied CKD murine models. Kidney OPN gene expression and urinary OPN/Cr ratios increased before changes in traditional biochemical markers of kidney function. Moreover, a reduction of nephron numbers alone (by unilateral nephrectomy) was sufficient to induce OPN expression in residual nephrons and induction of CKD in OPN-null mice fed excess phosphate resulted in severe nephrocalcinosis. Neutralization of the ASARM motif of OPN in phosphaturic mice resulted in severe nephrocalcinosis that mimicked OPN-null CKD mice. Lastly, in vitro experiments revealed calcium-phosphate nanocrystals to induce OPN expression by tubular epithelial cells directly.

Conclusions

Kidney OPN expression increases in early CKD and serves a critical role in maintaining tubular mineral solubility when tubular phosphate concentrations are exceedingly high, as in late-stage CKD. Calcium-phosphate nanocrystals may be a proximal stimulus for tubular OPN production.

Hydroxyproline stimulates inflammation and reprograms macrophage signaling in a rat kidney stone model

Meals rich in oxalate are associated with calcium oxalate (CaOx) kidney stone disease. Hydroxy-L-proline (HLP) is an oxalate precursor found in milk and collagen-containing foods. HLP has been shown to induce CaOx crystal formation in rodents. The purpose of this study was to evaluate the effect of HLP induced oxalate levels on inflammation and renal leukocytes during crystal formation. Male Sprague-Dawley rats (6-8 weeks old) were fed a control diet containing no oxalate for 3 days before being randomized to continue the control diet or 5% HLP for up to 28 days. Blood, 24 h urine, and kidneys were collected on Days 0, 7, 14, or 28. Urinary oxalate levels, crystal deposition, and renal macrophage markers were evaluated using ion chromatography-mass spectrometry, immunohistochemistry, and qRT-PCR. Renal leukocytes were assessed using flow cytometry and RNA-sequencing. HLP feeding increased urinary oxalate levels and renal crystal formation in animals within 7 days. HLP also increased renal macrophage populations on Days 14 and 28. Transcriptome analysis revealed that renal macrophages from animals fed HLP for 7 days were involved in inflammatory response and disease, stress response to LPS, oxidative stress, and immune cell trafficking. Renal macrophages isolated on Day 14 were involved in cell-mediated immunological pathways, ion homeostasis, and inflammatory response. Collectively, these findings suggest that HLP-mediated oxalate levels induce markers of inflammation, leukocyte populations, and reprograms signaling pathways in macrophages in a time-dependent manner. Additional studies investigating the significance of oxalate on renal macrophages could aid in our understanding of kidney stone formation.

Mechanism of ketotifen fumarate inhibiting renal calcium oxalate stone formation in SD rats

OBJECTIVES

To investigate the inhibitory effect of ketotifen fumarate (KFA), a mast cell membrane stabilizer, on renal calcium oxalate stone (CaOx) formation and its possible molecular mechanism.

METHODS

We used the Gene Ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) database for functional and pathway enrichment analyses of osteopontin (OPN), CD44 and fibronectin (FN). Blood biochemistry, reactive oxygen species ratio (ROS), mast cells, proteins (CD44, OPN and FN) and OPN receptor integrin family genes were detected by ELISA, flow cytometry, immunohistochemistry and RT-QPCR, respectively.

RESULTS

The crystal area of CaOx in the KFA and Control group was significantly smaller than that in the Model group. The number of activated mast cells, the expression levels of OPN and CD44 in the Control and KFA groups were significantly lower than those in the Model group, and the percentage of ROS in the KFA group was also significantly lower than that in the Model group. The mRNA expression levels of ITGB1, ITGA9, ITGAV and ITGA4 genes in the prominent OPN receptor integrin family increased significantly in the Model group.

CONCLUSIONS

Ketotifen can effectively inhibit the crystal formation of CaOx and reduce the inflammatory response of tissue in SD rats. The mechanism may be to reduce the infiltration and activation of mast cells in renal tissue and down-regulate the expression of OPN, CD44 and FN in renal tubules and renal interstitium. And affect the synthesis of integrins (ITGA9, ITGA4, ITGAV, ITGB1, ITGB3 and ITGB5) and ROS.

Atorvastatin Decreases Renal Calcium Oxalate Stone Deposits by Enhancing Renal Osteopontin Expression in Hyperoxaluric Stone-Forming Rats Fed a High-Fat Diet

Calcium oxalate (CaOx) is the major constituent of kidney stones. Growing evidence shows a close connection between hyperlipidemia, cardiovascular disease (CVD), and the formation of kidney stones. Owing to their antioxidant properties, statins control hyperlipidemia and may ameliorate CaOx stone formation. The present study was designed to investigate the suppressive effects of statins on CaOx urolithiasis and their potential mechanism. We used rats fed a high-fat diet (HFD) to achieve hyperlipidemia (HL) and hydroxyproline (HP) water to establish a hyperoxaluric CaOx nephrolithiasis model; the animals were administered statins (A) for 28 days. The rats were divided into eight groups treated or not with A, i.e., Control, HP, HL, HL + HP. HL aggravated urinary calcium crystallization compared to the control. Due to increased expression of renal osteopontin (OPN), a key anti-lithic protein, and reduced free radical production, the calcium crystals in the urinary bladder increased as renal calcium deposition decreased. The levels of the ion activity product of CaOx (AP(CaOx)) decreased after statins administration, and AP(Calcium phosphate) (CaP) increased, which suggested the dominant calcium crystal composition changed from CaOx to CaP after statin administration. In conclusion, atorvastatin decreases renal CaOx stone deposits by restoring OPN expression in hyperoxaluric rats fed a HFD.

Inflammatory Cells in Nephrectomy Tissue from Patients without and with a History of Urinary Stone Disease

BACKGROUND AND OBJECTIVES

Urinary stone disease has been associated with inflammation, but the specific cell interactions that mediate events remain poorly defined. This study compared calcification and inflammatory cell patterns in kidney tissue from radical nephrectomy specimens of patients without and with a history of urinary stone disease.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Nontumor parenchyma of biobanked radical nephrectomy specimens from age- and sex-matched stone formers (n=44) and nonstone formers (n=82) were compared. Calcification was detected by Yasue staining and inflammatory cell populations by immunohistochemistry for CD68 (proinflammatory M1 macrophages), CD163 and CD206 (anti-inflammatory M2 macrophages), CD3 (T lymphocytes), and tryptase (mast cells). Calcifications and inflammatory cells were quantified in cortex and medulla using Image-Pro analysis software.

RESULTS

Calcification in the medulla of stone formers was higher than in nonstone formers (P<0.001). M1 macrophages in the cortex and medulla of stone formers were greater than in nonstone formers (P<0.001), and greater in stone former medulla than stone former cortex (P=0.02). There were no differences in age, sex, body mass index, tumor characteristics (size, stage, or thrombus), vascular disease status, or eGFR between the groups. M2 macrophages, T lymphocytes, and mast cells did not differ by stone former status. There was a correlation between M1 macrophages and calcification in the medulla of stone formers (rho=0.48; P=0.001) and between M2 macrophages and calcification in the medulla of nonstone formers (rho=0.35; P=0.001). T lymphocytes were correlated with calcification in the cortex of both nonstone formers (rho=0.27; P=0.01) and stone formers (rho=0.42; P=0.004), whereas mast cells and calcification were correlated only in the cortex of stone formers (rho=0.35; P=0.02).

CONCLUSIONS

Higher medullary calcification stimulated accumulation of proinflammatory rather than anti-inflammatory macrophages in stone formers.

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

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