Coronary Artery Calcium Score and Association with Recurrent Nephrolithiasis: The Multi-Ethnic Study of Atherosclerosis

Vascular calcification in kidney stone formers: the impact of age and stone composition

An increased prevalence of vascular calcification (VC) has been reported in kidney stone formers (KSFs), along with an elevated cardiovascular risk. The aim of the current study is to assess whether VC in these patients develops at a younger age and is influenced by stone composition. This single-center, matched case-control study included KSFs with uric acid or calcium oxalate stones (diagnosed based on stone analysis) and age- and sex-matched controls without a history of nephrolithiasis. The prevalence and severity of abdominal aortic calcification (AAC) and bone mineral density (BMD) were compared between KSFs and non-KSFs. In total, 335 patients were investigated: 134 with calcium oxalate stones, 67 with uric acid stones, and 134 controls. Overall, the prevalence of AAC was significantly higher among calcium stone formers than among the controls (67.9% vs. 47%, p = 0.002). In patients under 60 years of age, those with calcium oxalate stones exhibited both a significantly elevated AAC prevalence (61.9% vs. 31.3%, p = 0.016) and severity (94.8 ± 15.4 vs. 30.3 ± 15.95, p = 0.001) compared to the controls. Within the age group of 40-49, osteoporosis was identified only in the KSFs. Multivariate analysis identified age, smoking, and the presence of calcium stones as independent predictors of AAC. This study highlights that VC and osteoporosis occur in KSFs at a younger age than in non-stone-formers, suggesting potential premature VC. Its pathogenesis is intriguing and needs to be elucidated. Early evaluation and intervention may be crucial for mitigating the cardiovascular risk in this population.

Association Between Physical Activity and the Prevalence of Kidney Stones in American Adults: Results From a Multiyear National Survey

OBJECTIVE

To investigate the association between physical activity (PA) and the prevalence of kidney stones.

METHODS

A cross-section study was conducted using data from National Health and Nutrition Examination Survey 2007-2018. PA was evaluated based on the Global Physical Activity Questionnaire. Multivariable logistic regression was performed to elucidate the association between PA (patterns, intensity, duration, and frequency of moderate and vigorous PA) and the prevalence of kidney stones after adjusting for potential confounders. Stratified and interaction analyses were conducted to detect potential effect modifiers. In addition, PA was assessed using metabolic equivalent and physical volume, and followed the regression above. Water intake was obtained from the day 2 dietary recall and was included in the sensitivity analysis.

RESULTS

A total of 34,390 participants were included in the analysis. The multivariable logistic regression revealed that individuals who engaged in moderate PA for 30-60 minutes per day had a significant inverse association with the prevalence of kidney stones in the fully adjusted model (odds ratio=0.804, 95% confidence interval 0.700 to 0.923), while no more significant finding was observed for other PA parameters. Interaction and stratified analyses indicated no covariate modifying the association. The results above were robust in the sensitivity analysis.

CONCLUSION

The duration of moderate PA (30-60 min/d) is inversely associated with the prevalence of kidney stones, while no more significant association was observed between other PA parameters (including patterns, intensity, duration, and frequency of vigorous PA, frequency of moderate PA) and kidney stones.

Vascular calcification on the risk of kidney stone: a meta-analysis

BACKGROUND

The association between vascular calcification (VC) and kidney stone is still inconclusive. Therefore, we conducted a meta-analysis to estimate the risk of kidney stone disease in subjects with VC.

METHODS

To identify publications from related clinical studies, we performed a search on PubMed, Web of Science, Embase, and Cochrane Library databases from their inceptions until 1 September 2022. According to obvious heterogeneity, a random-effects model was used to calculate the odds ratios (ORs) and corresponding 95% confidence intervals (CIs). Subgroup analysis was conducted trying to dissect the effects of VC in different segments and population regions in predicting kidney stone risk.

RESULTS

Seven articles were included with a total number of 69,135 patients, of which 10,052 have vascular calcifications and 4728 have kidney stones. There was a significantly higher risk of kidney stone disease in participants with VC versus control (OR = 1.54, 95% CI: 1.13-2.10). Sensitivity analysis confirmed the stability of the results. VC can be separated into abdominal, coronary, carotid, and splenic aortic calcification while pooled analysis of abdominal aorta calcification did not indicate a significant higher kidney stone risk. An obvious higher risk of kidney stone was observed in Asian VC patients (OR = 1.68, 95% CI: 1.07-2.61).

CONCLUSION

Combined evidence of observational studies suggested patients with VC may be associated with an increased risk of kidney stone disease. Despite the predictive value was relatively low, it is still worth noting that patients with VC are under the threat of kidney stone disease.

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.

Nephrolithiasis is associated with the severity of coronary artery calcification, but not with coronary artery stenosis

PURPOSE

Emerging data have indicated that nephrolithiasis is possibly associated with subclinical coronary artery disease (CAD). Considering that a significant proportion of obstructive CAD in non-elderly individuals occurs in those without detectable calcium score (CACS), this study aimed to investigate whether nephrolithiasis is still associated with CAD as assessed by coronary computed tomography (CT)-derived luminal stenosis [using Gensini score (GS)].

METHODS

A total of 1170 asymptomatic adults without known CAD who underwent health examinations were recruited. Nephrolithiasis was assessed using abdominal ultrasonography (US). Individuals with a self-reported stone history, but no evidence of nephrolithiasis were excluded. The CACS and GS were measured using 256-slice coronary CT.

RESULTS

Nearly half of these patients had a CACS > 0 (48.1%), and a higher prevalence of nephrolithiasis was observed than in those who had zero CACS (13.1% vs. 9.7%). However, no significant intergroup difference in GS was detected. A greater proportion of stone formers than non-stone formers had a higher risk category, whereas no significant difference was noted in Gensini category. Multiple linear regression analyses showed that the CACS independently predicted the presence of nephrolithiasis after adjustment. Importantly, we found that stone formers had a nearly threefold higher risk than non-stone formers of developing severe coronary calcification (CAC > 400).

CONCLUSIONS

Nephrolithiasis was significantly associated with coronary artery calcification presence and severity, but not coronary luminal stenosis in patients without known CAD. Accordingly, the relationship between stone disease and CAD remains controversial, and additional studies are imperative to validate these findings.

Increased renal uptake and urine excretion of oxidized LDL is possibly associated with formation of large calcium oxalate nephrolithiasis: a preliminary study

PURPOSE

Growing evidence have suggested an association between nephrolithiasis and cardiovascular disease (CVD) with unclear mechanism. Oxidized low-density lipoproteins (oxLDL) induces atherosclerosis and was found to be the possible link between these two diseases. Our study aimed to examine the serum, urine and kidney expression of oxLDL in relation to large calcium oxalate (CaOx) renal stone disease.

METHODS

A total of 67 large CaOx dominant renal stone patients and 31 stone-free controls were enrolled in the prospective case-control study. All participants were without known CVD history. Serum, urine, and kidney biopsy were collected before and during percutaneous nephrolithotomy, respectively. Enzyme-linked immunosorbent assays were used to assess serum and urine oxLDL, lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1), and high-sensitivity C-reactive protein (hsCRP).

RESULTS

There was no significantly difference in circulating oxLDL, but serum hsCRP was significantly near two-fold higher in nephrolithiasis patients. Serum hsCRP was also correlated with stone maximal length. Urine oxLDL was significantly higher in the nephrolithiasis group and correlated with serum hsCRP and stone maximal length. Increased oxLDL uptake in kidney was found in nephrolithiasis patients, whereas no significantly renal expression of oxLDL was observed in controls.

CONCLUSIONS

The renal uptake of oxLDL with increased oxLDL excretion from large CaOx renal stone formers, independent of increased circulating oxLDL, is a novel pathological finding in kidney stone disease and brings attention to the possible involvement of renal steatosis in the process of urolithiasis formation.

Epidemiology of Kidney Stones

In the past two decades, major breakthroughs that improve our understanding of the pathophysiology and therapy of kidney stones (KS) have been lacking. The disease continues to be challenging for patients, physicians, and healthcare systems alike. In this context, epidemiological studies are striving to elucidate the worldwide changes in the patterns and the burden of the disease and identify modifiable risk factors that contribute to the development of kidney stones. Our expanding knowledge of the epidemiology of kidney stones is of paramount importance and largely upgrades the modern management of the disease. In this paper, we review the variables affecting prevalence and incidence, including age, gender, race, ethnicity, occupation, climate, geography, systemic diseases, diabetes, vascular disease, chronic kidney disease, and dietary risk factors relevant to kidney stones.

Unravelling the Complex Relationship between Diet and Nephrolithiasis: The Role of Nutrigenomics and Nutrigenetics

Nephrolithiasis is an increasingly prevalent condition, especially in high income countries, and is associated with high morbidity. Extraordinary progress in genetics made the identification of genetic forms of nephrolithiasis possible. These genetic diseases are usually rare and do not account for the most common forms of nephrolithiasis that are the result of several factors such as environment, dietary habits, and predisposing genes. This knowledge has shaped what we classify as nephrolithiasis, a condition that is now recognized as systemic. How and to what extent all these factors interact with one another and end in kidney stone formation, growth, and recurrence is not completely understood. Two new research fields have recently been trying to give some answers: nutrigenomics and nutrigenetics. These fields have the aim of understanding the intricate diet/genome interface that influences gene expression regulation mainly through epigenetic mechanisms and results in specific medical conditions such as cancer, metabolic syndrome, and cardiovascular diseases. Epigenetics seems to play a crucial role and could represent the link between environmental factors, that we are constantly exposed to, and risk factors for nephrolithiasis. In this systematic review, we summarize all the available evidence of proven or hypothesized epigenetic mechanisms related to nephrolithiasis.

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.

The Association between Aortic Calcification Index and Urinary Stones: A Cross-Sectional Study

Background: It is believed that vascular calcification and urinary stones may possibly have a shared mechanism. However, the association between vascular calcification and urinary stones is largely unexplored. Using the aortic calcification index (ACI) as a clinical indicator of vascular calcification, the present study aimed to examine the association between the ACI and urinary stones. Methods: This cross-sectional study included 282 patients hospitalized for either urinary stones or other urological diseases from January 2020 to December 2021 at the Department of Urology and Lithotripsy in Peking University People’s Hospital. Among them, 137 and 145 patients were divided into the stone group and the non-stone group. Multivariable logistic regression analysis was performed to examine the association between the ACI and urinary stones. The restricted cubic splines model was used to further explore the dose−response relationship between the ACI and urinary stones. Results: The median (Q1−Q3) age of the study population was 59.0 (47.0−67.0) years. After adjusting coronary heart disease, triglycerides, glucose, serum creatinine, uric acid, urea, calcium, and eGFR, the ACI was independently associated with urinary stones (odds ratio [OR], 1.07; 95% confidence interval [CI], 1.03−1.11) in a linear dose−response pattern (p for non-linearity =0.153). Age was found to interact with the effect of the ACI on urinary stones (p for interaction <0.001). Conclusions: This study found that the ACI was independently associated with urinary stones in a linear dose−response manner. Our results indicate that the ACI might be a helpful indicator for identifying populations at risk for urinary stones.

Vascular Calcification Is Associated with Fetuin-A and Cortical Bone Porosity in Stone Formers

Background: Nephrolithiasis has been associated with bone loss and vascular calcification (VC), reflecting abnormal extraosseous calcium deposition. Fetuin-A (Fet-A) acts as a potent inhibitor of ectopic mineralization. The aim of the present study was to evaluate the prevalence of VC in stone formers (SF) and non-stone formers (NSF) and to investigate potential determinants of VC among SF, including circulating levels of Fet-A and bone microarchitecture parameters. Methods: Abdominal aortic calcification (AAC) was assessed using available computed tomography in SF and in age-, sex-, and BMI-matched NSF (potential living kidney donors). Serum Fet-A was measured in stored blood samples from SF. Bone microarchitecture parameters were obtained as a post hoc analysis of a cross-sectional cohort from young SF evaluated by high-resolution peripheral quantitative computed tomography (HR-pQCT). Results: A total of 62 SF (38.0 [28.0−45.3] years old) and 80 NSF (40.0 [37.0−45.8] years old) were included. There was no significant difference in AAC scores between SF and NSF. However, when dividing SF according to mean AAC score, below <5.8% (n = 33) or above ≥5.8% (n = 29), SF with higher AAC presented significantly higher BMI and tibial cortical porosity (Ct.Po) and significantly lower serum HDL, klotho, Fet-A, and eGFR. Urinary calcium did not differ between groups, but fractional excretion of phosphate was higher in the former. Upon multivariate regression, BMI, serum Fet-A, and tibial Ct.Po remained independently associated with AAC. Conclusions: This study suggests an association between reduced circulating Fet-A levels and increased bone Ct.Po with VC in SF.

Kidney stone disease and cardiovascular events: a study on bidirectional causality based on mendelian randomization

Background

Kidney stone disease (KSD) has been reported to be associated with several cardiovascular diseases. However, the causality between the conditions remains unknown. In the study, we performed a study on bidirectional causality by two-sample Mendelian randomization (MR) to investigate the causality between KSD and cardiovascular diseases including coronary atherosclerosis, hypertension, and cardiomyopathy.

Methods

In the recent study, we performed a bidirectional two-sample MR study using available genome-wide association summary data from the online database MRBASE. We identified genetic variants associated with KSD in one European population from UK Biobank (version 2, n=462,933). Two phenotypes of samples were chosen from the population to define our genetic instrumental variables: (I) samples with the phenotype of kidney stone/ureter stone/bladder stone (ukb-b-8297), and (II) samples with the phenotype of kidney stone surgery/lithotripsy (ukb-b-13537). For cardiovascular diseases, we picked up another independent European population from FinnGen Biobank (n=93,421). We selected the exposure and outcome SNPs and then performed the two-sample MR using R package.

Results

After bidirectional causality by two-sample MR, we verified that genetic predisposition to KSD could increase the risk of coronary atherosclerosis (OR: 4.45×1037; SE=±7.80×10¹⁴, P for MR-Egger =0.024) and cardiomyopathy (OR: 5.35×10¹³; SE=±7.18×10⁶, P for IVW=0.045 for finn-a-I9_CARDMYO, and OR: 3.60×10²⁵; SE=±3.26×10¹², P for IVW=0.041 for finn-a-I9_CARDMYOOTH) when we used ukb-b-13537 as exposure group. Furthermore, hypertension could increase the risk of KSD (OR: 1.001; SE=±1.00, P for IVW=0.003) when we used ukb-b-8297 as exposure group, without detected pleiotropy bias (P>0.05).

Conclusions

We confirmed KSD may trigger causal pathological processes including coronary atherosclerosis and cardiomyopathy. Furthermore, hypertension may causally affect KSD.

An Immune Atlas of Nephrolithiasis: Single-Cell Mass Cytometry on SIRT3 Knockout and Calcium Oxalate-Induced Renal Injury

Background

As a common urological disease with a high recurrence rate, nephrolithiasis caused by CaOx may elicit a strong immunologic response. We present a CyTOF-based atlas of the immune landscape in nephrolithiasis models to understand how the immune system contributes to, and is affected by, the underlying response caused by SIRT3 knockout and CaOx inducement.

Materials and Methods

We performed a large-scale CyTOF analysis of immune cell abundance profiles in nephrolithiasis. The immunophenotyping data were collected from four different mouse models, including the SIRT3 wild-type or knockout, including and excluding CaOx inducement. Unsupervised analysis strategies, such as SPADE and viSNE, revealed the intrarenal resident immune components and the immune alterations caused by SIRT3 knockout and CaOx-induced renal injury.

Results

An overview analysis of the immune landscape identified T cells and macrophages as the main immune cell population in nephrolithiasis models. Highly similar phenotypes were observed among CD4⁺ and CD8⁺ T cell subsets, including cells expressing Ki67, Ly6C, Siglec-F, and TCRβ. Macrophages expressed a characteristic panel of markers with varied expression levels including MHC II, SIRPα, CD11c, Siglec-F, F4/80, CD64, and CD11b, indicating more subtle differences in marker expression than T cells. The SIRT3^KO/CaOx and SIRT3^WT/CaOx groups exhibited global differences in the intrarenal immune landscape, whereas only small differences existed between the SIRT3^KO/CaOx and SIRT3^KO/Ctrl groups. Among the major immune lineages, the response of CD4⁺ T cells, NK cells, monocytes, and M1 to CaOx inducement was regulated by SIRT3 expression in contrast to the expression changes of B cells, DCs, and granulocytes caused by CaOx inducement. The panel of immune markers influenced by CaOx inducement significantly varied with and without SIRT3 knockout.

Conclusion

In a CaOx-induced nephrolithiasis model, SIRT3 has a critical role in regulating the immune system, especially in reducing inflammatory injury. The characteristic panel of altered immune clusters and markers provides novel insights leading to improved prediction and management of nephrolithiasis.

Association between aortic calcification and the presence of kidney stones: calcium oxalate calculi in focus

PURPOSE

The current research is aimed at analyzing the relationship between kidney stone (KS) and abdominal aortic calcification (AAC) and the relationship between KS components and AAC.

METHODS

This is a retrospective, case-control study. Kidney stone formers (KSFs) were treated at the Department of Urology, West China Hospital, Sichuan University for urological calculus disease from January 2014 to January 2020. Matched non-stone formers (non-SFs) were drawn from the same hospital for routine health examination from January 2018 to February 2019. Research-related information was collected and reviewed retrospectively from the hospital's computerized records. AAC were evaluated using available results of computed tomography imaging and abdominal vascular ultrasound. The relationships of AAC between KSFs and non-SFs were compared. The composition of renal calculi was analyzed by Fourier-transform infrared spectrophotometer. KSFs were divided into AAC groups and non-AAC based on AAC. The relationship of the composition of renal calculi between AAC and non-AAC were compared. The independent-sample t test, the chi-squared test and binary logistics regression were performed.

RESULTS

Altogether, 4516 people were included, with 1027 KSFs and 3489 non-SFs. There were no significant differences in the laboratory parameters between KSFs and non-SFs. The association between the presence of AAC and KS was significant in multivariable model 2 [adjusting hypertension, diabetes mellitus, fasting blood glucose, uric acid, serum triglyceride (TG), serum calcium, and urine pH] (OR 5.756, 95% CI 4.616-7.177, p < 0.001). The result of KSFs showed that calcium oxalate calculi (CaOx) was significantly associated with AAC in multivariable model 3 (adjusting age, hypertension, diabetes mellitus, drinking history, smoking history, and TG) (OR 1.351, 95% CI 1.002-1.822, p = 0.048).

CONCLUSIONS

The current study pioneered the revelation of the relationship between CaOx and AAC. Through an elimination of the confounding factors, the study demonstrated that KS and AAC were connected.

Disparities in Kidney Stone Disease: A Scoping Review

PURPOSE

We reviewed the available evidence regarding health disparities in kidney stone disease to identify knowledge gaps in this area.

MATERIALS AND METHODS

A literature search was conducted using PubMed®, Embase® and Scopus® limited to articles published in English from 1971 to 2020. Articles were selected based on their relevance to disparities in kidney stone disease among adults in the United States.

RESULTS

Several large epidemiological studies suggest disproportionate increases in incidence and prevalence of kidney stone disease among women as well as Black and Hispanic individuals in the United States, whereas other studies of comparable size do not report racial and ethnic demographics. Numerous articles describe disparities in imaging utilization, metabolic workup completion, analgesia, surgical intervention, stone burden at presentation, surgical complications, followup, and quality of life based on race, ethnicity, socioeconomic status and place of residence. Differences in urinary parameters based on race, ethnicity and socioeconomic status may be explained by both dietary and physiological factors. All articles assessed had substantial risk of selection bias and confounding.

CONCLUSIONS

Health disparities are present in many aspects of kidney stone disease. Further research should focus not only on characterization of these disparities but also on interventions to reduce or eliminate them.

Randall's plaque and calcium oxalate stone formation: role for immunity and inflammation

Idiopathic calcium oxalate (CaOx) stones often develop attached to Randall's plaque present on kidney papillary surfaces. Similar to the plaques formed during vascular calcification, Randall's plaques consist of calcium phosphate crystals mixed with an organic matrix that is rich in proteins, such as inter-α-trypsin inhibitor, as well as lipids, and includes membrane-bound vesicles or exosomes, collagen fibres and other components of the extracellular matrix. Kidney tissue surrounding Randall's plaques is associated with the presence of classically activated, pro-inflammatory macrophages (also termed M1) and downregulation of alternatively activated, anti-inflammatory macrophages (also termed M2). In animal models, crystal deposition in the kidneys has been associated with the production of reactive oxygen species, inflammasome activation and increased expression of molecules implicated in the inflammatory cascade, including osteopontin, matrix Gla protein and fetuin A (also known as α2-HS-glycoprotein). Many of these molecules, including osteopontin and matrix Gla protein, are well known inhibitors of vascular calcification. We propose that conditions of urine supersaturation promote kidney damage by inducing the production of reactive oxygen species and oxidative stress, and that the ensuing inflammatory immune response promotes Randall's plaque initiation and calcium stone formation.

The relationship between vascular calcifications and urolithiasis in a large, multiethnic patient population

Several studies have reported associations between vascular calcifications and urinary stone disease (USD). However, results have been inconsistent and the majority of studies did not report on race/ethnicity. We examined the association between vascular calcifications and USD in a large, racially/ethnically diverse patient population. We identified 672 USD cases and 672 controls (i.e., patients without a history of USD) from patients who underwent non-contrast CT imaging at Montefiore Medical Center in Bronx, New York between 2004 and 2013. Controls were matched to cases on age, sex and race/ethnicity. The non-contrast CT imaging was used to measure abdominal aortic calcification (AAC) and calculate the AAC severity score. Logistic regression models were used to examine associations of AAC presence and severity score with risks of USD and stone types. Cases and controls had similar AAC prevalence (45.2% vs. 44.8%, p = 0.87), and AAC severity score (median 10 vs. 9.3, p = 0.47). The presence of AAC (OR = 0.98, 95% CI 0.78-1.23; p = 0.86) or AAC severity score were not associated with risk of USD: ORs of 0.96, 0.87, 1.07 and 1.03 for increasing AAC quartiles (p-trend = 0.54). There were also no associations in the stratified analyses by race/ethnicity or by sex. However, when USD patients were stratified by stone type, brushite/apatite stone formers had an inverse association with the lowest quartile of AAC severity score (OR = 0.35, 95% CI 0.11-0.84, p = 0.04) in comparison to patients without AAC. Overall, we found no association between vascular calcifications and risk of urinary stone disease in this large, hospital-based, case-control study.

Crosstalk between Renal and Vascular Calcium Signaling: The Link between Nephrolithiasis and Vascular Calcification

Calcium (Ca²⁺) is an important mediator of multicellular homeostasis and is involved in several diseases. The interplay among the kidney, bone, intestine, and parathyroid gland in Ca²⁺ homeostasis is strictly modulated by numerous hormones and signaling pathways. The calcium-sensing receptor (CaSR) is a G protein–coupled receptor, that is expressed in calcitropic tissues such as the parathyroid gland and the kidney, plays a pivotal role in Ca²⁺ regulation. CaSR is important for renal Ca²⁺, as a mutation in this receptor leads to hypercalciuria and calcium nephrolithiasis. In addition, CaSR is also widely expressed in the vascular system, including vascular endothelial cells (VECs) and vascular smooth muscle cells (VSMCs) and participates in the process of vascular calcification. Aberrant Ca²⁺ sensing by the kidney and VSMCs, owing to altered CaSR expression or function, is associated with the formation of nephrolithiasis and vascular calcification. Based on emerging epidemiological evidence, patients with nephrolithiasis have a higher risk of vascular calcification, but the exact mechanism linking the two conditions is unclear. However, a dysregulation in Ca²⁺ homeostasis and dysfunction in CaSR might be the connection between the two. This review summarizes renal calcium handling and calcium signaling in the vascular system, with a special focus on the link between nephrolithiasis and vascular calcification.

Urolithiasis, Independent of Uric Acid, Increased Risk of Coronary Artery and Carotid Atherosclerosis: A Meta-Analysis of Observational Studies

Background and Aims

Recent epidemiological evidence indicates an association between urolithiasis and atherosclerosis; however, results are incongruous. Our aim is to summarize the association between urolithiasis and arteriosclerosis risk through a detailed meta-analysis.

Methods

Relevant studies published before April 2019 were identified by searching OVID, EMBASE, PubMed, Web of Science database, and Cochrane Library. The relationship between urolithiasis and the risk of atherosclerosis was assessed by using odds ratio (OR) values and the corresponding 95% confidence intervals (CIs), and the selection of fixed- or random-effects model based on heterogeneity.

Results

The meta-analysis includes 8 observational studies that contained 70,716 samples. Pooled results showed that urolithiasis was associated with an increased adjusted and unadjusted risk estimated for atherosclerosis (P=0.017 and P=0.017 and n = 65,751/70,716) with serum uric acid levels less than 6.0 mg/dl, it still showed that urolithiasis was associated with a higher risk of atherosclerosis (P=0.017 and I² = 0.0%, P=0.017 and P=0.017 and P=0.017 and

Conclusions

Urolithiasis is associated with an increased risk for atherosclerosis, especially in coronary artery and carotid atherosclerosis. Urolithiasis may be another potential risk factor of atherosclerosis, which is independent of serum uric acid levels.

Ectopic biomineralization in kidney stone formers compared to non-stone formers

Background

Kidney stone formers (SFs) are at increased risk of stroke, myocardial infarction, and atherosclerosis of the carotid and coronary arteries. These cardiovascular and urologic pathologies can result from ectopic biomineral deposition. The objectives of this study are: (I) to evaluate risk factors for ectopic biomineralization, and (II) to characterize the overall burden of ectopic minerals in known SFs compared to non-stone formers (NSFs) matched for these risk factors.

Methods

Presence and quantity of biominerals at eight anatomic locations (abdominal aorta, common iliac arteries, pelvic veins, prostate or uterus, mesentery, pancreas, and spleen) were determined in a case control study by retrospective analysis of clinical non-contrast computed tomography scans obtained from 190 SFs and 190 gender- and age-matched NSFs (renal transplant donors). Predictors of biomineralization were determined using negative binomial regression. A subgroup of 140 SFs and 140 NSFs were matched for risk factors for systemic biomineralization, and mineralization was compared between these matched SFs and NSFs using ordinal logistic regression.

Results

Hypertension, hyperlipidemia, diabetes mellitus, and smoking were more common amongst SFs. Risk factors for increased systemic biomineralization included history of nephrolithiasis, male gender, older age, and history of hyperlipidemia. When controlling for these comorbidities, SFs had significantly increased biomineralization systemically and at the abdominal aorta, iliac arteries, prostate, mesentery, pancreas, and spleen compared to NSFs.

Conclusions

The current study provides evidence that SFs are at increased risk of biomineralization systemically, independent of common risk factors of atherosclerosis.

Calcium Kidney Stones are Associated with Increased Risk of Carotid Atherosclerosis: The Link between Urinary Stone Risks, Carotid Intima-Media Thickness, and Oxidative Stress Markers

Previous studies have suggested that kidney stone formers are associated with a higher risk of cardiovascular events. To our knowledge, there have been no previous examinations of the relationship between carotid intima-media thickness (IMT) and urinary stone risk factors. This study was aimed toward an investigation of the association between dyslipidemia, IMT, and 24-hour urinalysis in patients with calcium oxalate (CaOx) or calcium phosphate (CaP) stones. We prospectively enrolled 114 patients with kidney stones and 33 controls between January 2016 and August 2016. All patients were divided into four groups, according to the stone compositions—CaOx ≥ 50% group, CaP group, struvite group, and uric acid stones group. Carotid IMT and the carotid score (CS) were evaluated using extracranial carotid artery doppler ultrasonography. The results of a multivariate analysis indicated that a higher serum total cholesterol (TC) and low-density lipoprotein (LDL) were all associated with lower urinary citrate and higher CS in both the CaOx ≥ 50% and CaP groups. Higher serum TC and LDL were also associated with increased serum 8-OHdG levels in both groups. The levels of carotid IMT and CS in the CaOx ≥ 50% and CaP groups were all significantly higher than in the controls. These findings suggest a strong link between dyslipidemia, carotid atherosclerosis, and calcium kidney stone disease.

Kidney Stone History and Adverse Outcomes After Percutaneous Coronary Intervention

OBJECTIVE

To determine whether kidney stone history is associated with adverse outcomes after percutaneous coronary intervention (PCI). Kidney stone formers have an increased risk of developing coronary artery disease; however, whether these patients have worse cardiac outcomes is unknown.

MATERIALS AND METHODS

We identified adult patients who underwent first-time PCI in Vanderbilt University Medical Center (VUMC) Synthetic Derivative from 2008 to 2016 (n = 11,289) and in a nationwide database of Taiwan (NHIRD) from 2005 to 2012 (n = 155,762). Odds ratios (ORs) of 30-day in-hospital mortality and hazard ratios (HRs) of 1-year and 3-year adverse outcomes associated with kidney stone history were estimated using a propensity score approach.

RESULTS

Overall, 294 and 12,286 stone formers undergoing PCI were identified in the VUMC and NHIRD, respectively. After matching, stone formers at VUMC were at higher risks of 30-day in-hospital mortality (OR 2.79, 95% CI 1.15-6.69) and 1-year (HR 1.59, 95% CI 1.13-2.24) and 3-year (HR 1.36, 95% CI 1.02-1.81) myocardial infarction. In the NHIRD, kidney stone history was associated with 1-year (HR 1.12, 95% CI 1.03-1.21) and 3-year (HR 1.14, 95% CI 1.06-1.22) myocardial infarction. In a sensitivity analysis, stone formers undergoing kidney stone surgery were marginally associated with 30-day in-hospital mortality (OR 1.21, 95% CI 0.99-1.48) and were associated with 3-year myocardial infarction (HR 1.13, 95% CI 1.02-1.25).

CONCLUSION

Kidney stone history is associated with poorer cardiac outcomes after PCI. Improving secondary cardiac prevention strategies after PCI may be necessary for patients with a history of kidney stone disease.

Evidence for disordered acid-base handling in calcium stone-forming patients

In stone formers (SFs) with idiopathic hypercalciuria, urine pH governs the mineral phase of stones. Calcium phosphate (CaP) SFs have higher urine pH than calcium oxalate (CaOx) SFs. Normal women have higher urine pH than men on fixed diets, accompanied by greater absorption of food alkali. Female CaP and male CaOx SFs have similar urine pH as same sex normal individuals, but male CaP and female CaOx SFs may have abnormal acid-base handling. We studied 25 normal individuals (13 men and 12 women), 17 CaOx SFs (11 men and 6 women), and 15 CaP SFs (8 men and 7 women) on fixed diets. Urine and blood samples were collected under fasting and fed conditions. Female CaOx SFs had lower urine pH and lower alkali absorption, fed, compared with normal women; their urine NH₄ was higher and urine citrate excretion lower than in normal women, consistent with their higher net acid excretion. Male CaOx SFs had higher urine citrate excretion and higher serum ultrafilterable citrate levels than normal men. Both male and female CaP SFs had higher urine pH fasting than same sex normal individuals, but only men were higher in the fed period, and there were no differences from normal in gut alkali absorption. CaP SFs of both sexes had higher urine NH₄ and lower urine citrate than same sex normal individuals. The lower urine pH of female CaOx SFs seems related to decreased gut alkali absorption, while the higher pH of CaP SFs, accompanied by higher urine NH₄ and lower urine citrate, suggests a proximal tubule disorder.

[Modifiable and non-modifiable risk factors for urolithiasis]

Knowledge of the risk factors for urolithiasis is the key for sufficient metaphylaxis and reduction of recurrence events. Modifiable risk factors include diet, drink quantity, occupation, environmental factors, number of pregnancies and the intestinal microbiome. The treatment of associated diseases, such as the various manifestations of metabolic syndrome can reduce the risk for urolithiasis and recurrences. Knowledge of non-modifiable risk factors, such as gender, ethnicity, positive family history as well as specific genetic defects and polymorphisms of the calcium and phosphate balance enables personalized counselling and follow-up of affected patients.

Nonrenal Systemic Arterial Calcification Predicts the Formation of Kidney Stones

Background: Recent data indicate that kidney stone formers (KSFs) may have increased biomineralization at anatomic sites throughout the body compared with nonstone formers (NSFs). The objective of this study is to compare the volume of nonrenal systemic calcifications between KSF and NSF by using a standardized system to analyze calcifications in the abdominal aorta (AA) and splenic artery (SA). Methods: The NSF cohort was obtained from a kidney donor's prospectively maintained database. One hundred ninety-seven NSF were matched to 197 KSF based on age, gender, and body mass index. Noncontrast CT scans were evaluated and semiautomated CT software was utilized to provide an AA and SA calcification Agatston score. Wilcoxon rank-sum test was used on continuous variables and chi-squared test or Fisher's exact test on categorical variables. Odds ratios (ORs) were given for a variable's influence on the formation of stones or calcifications. Results: AA and SA calcifications were more prevalent in the KSF group (p = 0.011 and p = 0.027, respectively). KSFs were 1.9 times more likely to have intermediate or severe AA calcification than NSFs (OR = 1.9, p = 0.004). Severe AA calcifications had even a greater association (OR = 3.1, p = 0.019). KSFs were also more likely to have SA, but this did not reach statistical significance (OR = 3.7, p = 0.103). Conclusion: Patients with increased systemic calcifications, specifically aortic or splenic calcifications, may be at an increased risk for future kidney stone formation. Patients with these imaging findings and additional risk factors for stone disease may be counseled on the future risk of stones.

Helper T-cell signaling and inflammatory pathway lead to formation of calcium phosphate but not calcium oxalate stones on Randall's plaques

OBJECTIVES

To elucidate the difference in the lithogenesis of calcium oxalate and calcium phosphate stones.

METHODS

Renal papillary tissues were obtained from 23 idiopathic calcium oxalate and seven calcium phosphate stone patients who had undergone endoscopic lithotripsy. Samples were individually collected from two different regions in each patient: the papillary mucosa containing Randall's plaque and mucosa not containing Randall's plaque. A microarray analysis was carried out on those tissues to compare their gene expression patterns. Furthermore, a causal pathway analysis comparing their differences was carried out.

RESULTS

Cluster analysis showed that gene expression profiles of calcium phosphate stone patients markedly differed from those of calcium oxalate stone patients. Disease and function analysis showed that Randall's plaque-containing tissues of calcium phosphate stone-forming patients had significantly higher movement and migration of mononuclear leukocytes, and lower tendency toward infection and lymph node formation than Randall's plaque-containing tissues of calcium oxalate stone formers. Additional pathway analysis showed increased immune cell signaling in calcium phosphate formers, such as the helper T cell 1 and 2 pathways, which was confirmed by their messenger ribonucleic acid expression.

CONCLUSIONS

The present results show the upregulation of helper T-cell signaling pathways in Randall's plaque-containing papillae in calcium phosphate, but not in calcium oxalate stone formers. Thus, helper T-cell immune responses and the related inflammatory processes seem to lead to the formation of calcium phosphate stones on Randall's plaques.

Cross-talk between renal lithogenesis and atherosclerosis: an unveiled link between kidney stone formation and cardiovascular diseases

The prevalence of kidney stones and cardiovascular diseases (CVDs) are increasing throughout the world. Both diseases are chronic and characterized by accumulation of oxidized proteins and lipids in the renal tissue and arterial wall, respectively. Emerging studies have revealed a positive association between nephrolithiasis and CVDs. Based on preclinical and clinical evidences, this review discusses: (i) stone forming risk factors, crystal nucleation, aggregation, injury-induced crystal retention, and stone formation, (ii) CVD risk factors such as dyslipidemia, perturbation of gut microbiome, obesity, free radical-induced lipoprotein oxidation, and retention in the arterial wall, subsequent foam cell formation, and atherosclerosis, (iii) mechanism by which stone forming risk factors such as oxalate, calcium, uric acid, and infection contribute toward CVDs, and (iv) how CVD risk factors, such as cholesterol, phospholipids, and uric acid, contribute to kidney stone formation are described.

Impact of Statin Intake on Kidney Stone Formation

OBJECTIVE

To determine whether statin intake affects nephrolithiasis risk, and whether higher lipid levels correlate with stone risk. Dyslipidemia is a known independent risk factor for urolithiasis, and emerging evidence suggests common biological pathways. Previous work has suggested that statins protect against new stone formation, but these findings have not been verified by other investigators.

METHODS

We queried our Institution's Electronic Data Warehouse for all patients who were newly diagnosed with hyperlipidemia between 2009 and 2011, and had never taken a statin drug. These patients' clinical outcomes were followed until 2015, to assess whether they had been newly prescribed statins and whether they had developed symptomatic urolithiasis. Patient demographics, stone risk factors, prescription data, and serum lipid values were collected.

RESULTS

A total of 101,259 patients met inclusion criteria, 47.8% of whom received a statin prescription during the study period. Patients prescribed statins were significantly older, had a greater likelihood of osteoporosis, hemiplegia, immobility, and more likely to take a thiazide diuretic. Patients without a history of urolithiasis who were started on statin therapy were significantly less likely to develop new stones than patients not taking statins. This protective effect was even greater in patients with a history of stone disease. Lipid parameters (low-density lipoprotein, triglyceride, cholesterol) were lower in the statin-treated group, suggesting overall compliance with these medications.

CONCLUSION

Our data confirm previous work that statins protect against urinary stone formation; however, the underlying mechanism seems to be distinct from statins' lipid-lowering effect.

Hypothesis: Potential Utility of Serum and Urine Uromodulin Measurement in Kidney Transplant Recipients?

Seventy years after its discovery, studies of the myriad properties, and potential disease associations of uromodulin are now burgeoning. Although normative ranges for serum/plasma uromodulin concentrations were established over 30 years ago, their external validation occurred only in very recent, larger studies. As tubular function indices, serum and urinary uromodulin may be more sensitive indicators of kidney graft dysfunction undetected by glomerular filtration markers, or proteinuria. Moreover, 2 sizable, just published longitudinal reports revealed that lower serum uromodulin levels were associated with cardiovascular disease (CVD) outcomes, total mortality, and infectious disease deaths, in patients with known or suspected coronary heart disease. Preliminary longitudinal studies have reported that reduced levels of plasma or serum uromodulin were linked to progression to end-stage renal disease in chronic kidney disease patients, and graft failure in kidney transplant recipients (KTRs). Conflicting data on the associations, or lack thereof, between lower urinary uromodulin concentrations and accelerated loss of renal function, or renal failure, in nontransplant chronic kidney disease patients, are perhaps due, in part, to analytical limitations in determining urine uromodulin. Potential longitudinal associations between serum and urinary uromodulin concentrations, and CVD outcomes, graft failure, and all-cause mortality, await validation in large, diverse cohorts of chronic KTRs. Taking advantage of an efficient case-cohort design scheme, we demonstrate how the completed FAVORIT clinical trial cohort might be ideally suited to evaluate these associations. Using available case-cohort sample data, statistical power simulations are provided to detect relative risk estimates of 1.50 for CVD (n = 309 events), 1.56 for graft failure (n = 223 events) or 1.50 for death from any cause (n = 320 events), comparing values below the median, to values equal to or above the median for serum uromodulin values. Edifying data such as these would advance our understanding of the hypothetical utility of uromodulin measurement in KTRs considerably.

Vascular Disease and Kidney Stones: Abdominal Aortic Calcifications Are Associated with Low Urine pH and Hypocitraturia

OBJECTIVE

Vascular calcifications are associated with nephrolithiasis. Although studies have demonstrated correlations with vascular disease and calcium stones in kidney stone formers (KSF), an etiologic link has remained elusive. As a noncontrast CT (NCCT) scan is typically part of a stone evaluation, our objective was to evaluate the association of NCCT-based assessment of abdominal aortic calcifications (AACs) with 24-hour urine parameters and stone composition.

MATERIALS AND METHODS

Ninety-seven KSF were included with CT imaging and 24-hour urine studies. For each patient, semi-automated CT software was utilized to provide an AAC Agatston score from the celiac axis to the aortic bifurcation. Univariate analysis was performed to compare patients with or without AAC. Multivariate logistic regression was performed to assess for variables associated with 24-hour urine parameters and stone composition.

RESULTS

The presence of AAC was associated with hypertension, diabetes, peripheral vascular disease, and coronary artery disease. Patients with any AAC showed lower 24-hour urine citrate (399 vs 593 mg/day, p < 0.001) and lower 24-hour urine pH (5.862 vs 6.328, p = 0.003). When controlling for age, system comorbidities, the presence of AAC was associated with low urine pH <6 (odds ratio [OR] 2.86, p = 0.032) and hypocitraturia <320 mg/day (OR 4.37, p = 0.005). The receiver operating characteristic curve showed that increasing AAC was associated with low urine pH (area under the curve [AUC] 0.683, p = 0.002) and uric acid stone formation (AUC 0.698, p = 0.045).

CONCLUSIONS

NCCT-based diagnosis of AAC is associated with low urine pH, hypocitraturia, and uric acid stone formation. The presence of AAC could be considered an additional prognosticator for the utility of alkalinization therapy.

Urinary Stone Disease and Cardiovascular Disease Risk in a Rural Chinese Population

Introduction

Urinary stone disease (USD) is associated with cardiovascular disease (CVD) in Western populations. However, the prevalence and relationship between USD and CVD risk have not been fully examined in the Chinese population.

Methods

We performed a cross-sectional study of 10,281 participants in rural China. All subjects underwent renal ultrasound to detect USD, brachial−ankle pulsewave velocity (baPWV) measurement to estimate arterial stiffness, and ankle−brachial index (ABI) examination to detect peripheral arterial disease (PAD) (defined as ABI <0.9 on at least 1 side of the body).

Results

Mean age of the study population was 55.4 ± 10.0 years; 47.1% were men. Among all participants, 5.7% (n = 582) had USD, mean baPWV was 15.6 ± 3.2 m/s, and 4.0% had PAD. The prevalence of USD increased in parallel with mean arterial pressure, albuminuria, Framingham risk score, and baPWV. In multivariate analyses after adjustment for demographic characteristics, USD was significantly associated with an increased risk of hypertension (odds ratio [OR]: 1.32; 95% confidence interval [CI]: 1.08−1.62), albuminuria (OR: 2.17; 95% CI: 1.74−2.69), chronic kidney disease (OR: 2.11; 95% CI: 1.70−2.62), increased arterial stiffness (OR: 1.24; 95% CI: 1.01−1.52), and PAD (OR: 1.50; 95% CI: 1.04−2.16).

Discussion

In rural China, USD was associated with a high prevalence of traditional CVD risk factors, increased arterial stiffness, and PAD. The presence of USD should increase physician awareness of the concomitant presence of CVD risk factors.

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

In our previous report, M2-macrophage (Mφs) deficient mice showed increased renal calcium oxalate (CaOx) crystal formation; however, the role of Mφs-related-cytokines and chemokines that affect kidney stone formation remains unknown. Here, we investigated the role of M1/M2s in crystal development by using in vitro and in vivo approaches. The crystal phagocytic rate of bone marrow-derived M2Mφs was higher than that of bone marrow-derived Mφs and M1Mφs and increased on co-culture with renal tubular cells (RTCs). However, the amount of crystal attachment on RTCs reduced on co-culture with M2Mφs. In six hyperoxaluric C57BL/6J mice, M1Mφ transfusion and induction by LPS and IFN-γ facilitated renal crystal formation, whereas M2Mφ transfusion and induction by IL-4 and IL-13 suppressed renal crystal formation compared with the control. These M2Mφ treatments reduced the expression of crystal-related genes, such as osteopontin and CD44, whereas M1Mφ treatment increased the expression of pro-inflammatory and adhesion-related genes such as IL-6, inducible NOS, TNF-α, C3, and VCAM-1. The expression of M2Mφ-related genes was lower whereas that of M1Mφ-related genes was higher in papillary tissue of CaOx stone formers. Overall, our results suggest that renal crystal development is facilitated by M1Mφs, but suppressed by M2Mφs.