Klotho gene polymorphism of rs3752472 is associated with the risk of urinary calculi in the population of Han nationality in Eastern China

Effects of Klotho protein, vitamin D, and oxidative stress parameters on urinary stone formation and recurrence

PURPOSE

The present study aimed to investigate the effects of α-Klotho and oxidative stress markers on urinary stone disease (USD) and demonstrate their use as biochemical markers in USD.

METHODS

Among the 90 individuals included, 30 individuals were healthy controls (Group 1), 30 individuals presented with USD for the first time (Group 2), and 30 individuals demonstrated recurrent USD (Group 3). Serum levels of α-Klotho, vitamin D, malondialdehyde (MDA), total oxidant status, and total antioxidant status were determined using spectrophotometry analysis. Serum calcium and parathormone levels and 24-h urine calcium levels were measured via biochemical analysis.

RESULTS

No significant intergroup difference was noted in terms of age and sex. The groups had significant differences regarding α-Klotho, oxidative stress index (OSI), MDA, and 24-h urine calcium levels. α-Klotho was a determinant of 24-h urine calcium level and OSI. An increase of 1 pg/mL in α-Klotho level appeared to result in a decrease of 8.55 mg in 24-h urine calcium level and a decrease of 0.04 Arbitrary Unit in OSI. In patients experiencing USD for the first time, α-Klotho values were < 21.83 pg/mL and showed 66% sensitivity and 64% specificity. In individuals with recurrent stone formation, α-Klotho values below 19.41 pg/mL had 60% sensitivity and 77% specificity.

CONCLUSIONS

The biochemical markers investigated herein, i.e., α-Klotho, OSI, and MDA, were involved in the pathogenesis of stone formation and can be used in day-to-day clinical practices of urology clinics to identify patients at risk for both first time and recurrent USD.

Association of serum soluble α‑klotho with risk of kidney stone disease: a population-based cross-sectional study

BACKGROUND

The aim of the study was to explore the association of serum soluble klotho with kidney stone disease (KSD) in the general population over the age of 40 years in the United States.

METHODS

We integrated the data in National Health and Nutrition Examination Survey from 2007 to 2016 years. The relationship between serum soluble α‑klotho and prevalence of KSD was analyzed by constructing weighted multivariable logistic regression model, restricted cubic spline (RCS) curve, and subgroup analyses.

RESULTS

In the study, a total of 13,722 individuals were included in our study. A U-shaped association between serum soluble klotho and the risk of KSD was shown by the RCS curve (P value for nonlinear < 0.05). In the full adjusted model, compared with the lowest quartile of serum soluble α‑klotho, the adjusted odd ratios (95% confidence intervals) for KSD across the quartiles were (0.999 (0.859, 1.164), 1.005 (0.858, 1.176), and 1.061 (0.911, 1.235)). Subgroup analyses also showed that the U-shaped association of serum soluble α‑klotho with KSD was found among subjects who were age < 60 years, female or male, with or without hypertension, and BMI ≥ 30 kg/m2.

CONCLUSIONS

Our findings suggested that serum klotho levels had a U-shaped correlation with risk of KSD. When the Klotho level is at 818.66 pg/mL, prevalence of KSD is lowest. Therefore, maintaining a certain level of serum soluble α‑klotho could prevent the occurrence of KSD.

Predictive value of single-nucleotide polymorphism signature for nephrolithiasis recurrence: a 5-year prospective study

Background

Genetic variations are linked to kidney stone formation. However, the association of single nucleotide polymorphism (SNPs) and stone recurrence has not been well studied. This study aims to identify genetic variants associated with kidney stone recurrences and to construct a predictive nomogram model using SNPs and clinical features to predict the recurrence risk of kidney stones.

Methods

We genotyped 49 SNPs in 1001 patients who received surgical stone removal between Jan 1 and Dec 31 of 2012. All patients were confirmed stone-free by CT scan and then received follow-up at least 5 years. SNP associations with stone recurrence were analyzed by Cox proportion hazard model. A predictive nomogram model using SNPs and clinical features to predict the recurrence risk of kidney stones was developed by use of LASSO Cox regression.

Results

The recurrence rate at 3, 5, 7 years were 46.8%, 71.2%, and 78.4%, respectively. 5 SNPs were identified that had association with kidney stone recurrence risk. We used computer-generated random numbers to assign 500 of these patients to the training cohort and 501 patients to the validation cohort. A nomogram that combined the 14-SNPs-based classifier with the clinical risk factors was constructed. The areas under the curve (AUCs) at 3, 5 and 7 years of this nomogram was 0.645, 0.723, and 0.75 in training cohort, and was 0.631, 0.708, and 0.727 in validation cohort, respectively. Results show that the nomogram presented a higher predictive accuracy than those of the SNP classifier or clinical factors alone.

Conclusion

SNPs are significantly associated with kidney stone recurrence and should add prognostic value to the traditional clinical risk factors used to assess the kidney stone recurrence. A nomogram using clinical and genetic variables to predict kidney stone recurrence has revealed its potential in the future as an assessment tool during the follow-up of kidney stone patients.

Genetic Polymorphisms and Kidney Stones Around the Globe: A Systematic Review and Meta-Analysis

Objective: This study explores associations between recurrent kidney stones and genetic polymorphisms.

Methods: Meta-analysis of polymorphisms in renal stone cases versus control groups. Four electronic databases (PubMed, SCOPUS, EMBASE, and Web of Science) were searched up to 30 May 2021, using the keywords: “kidney stone” or “kidney calculi,” or “urolithiasis” or “nephrolithiasis” or “urinary calculi” and “genome” or “genetic” or “mutation” or “single nucleotide polymorphism.” Forrest plots, ORs, 95% CI, Chi-square (χ2)-test, and index of heterogeneity (I2) were calculated. Only studies with Newcastle–Ottawa scale (NOS) ≥ 6 were included for quality control, and Funnel, Begg’s, and Eager’s plots assessed publication bias. PROSPERO: CRD42022250427.

Results: Among 7,671 searched articles, 72 were included. Polymorphisms in VDR (OR: 1.20; 95% CI: 1.06–1.36), CASR (OR = 1.24; 95% CI: 1.01–1.52), Osteopontin (OR = 1.38; 95% CI: 1.09–1.74), and Urokinase genes (OR = 1.52; 95% CI: 1.02–2.28) showed a significant association with risk of urinary stone formation, while Klotho gene showed a protective effect (OR = 0.75; 95% CI: 0.57–0.99). The VDR gene polymorphism was frequent in Asians, whereas CASR polymorphism was frequent in European and North American populations.

Conclusion: Multifactorial nature of the stone formation, emphasizing the role of environmental factors, might explain contradictory results in the literature. While polymorphisms in VDR, CASR, Osteopontin, and Urokinase genes were associated with urinary stone formation, the Klotho gene showed a protective effect.

Mutation of Klotho rs3752472 protect the kidney from the renal epithelial cell injury caused by CaOx crystals through the Wnt/β-catenin signaling pathway

Calcium oxalate (CaOx) is a major contributor to urolithiasis, one of the most common urological diseases. Our previous study has shown that Klotho rs3752472 polymorphism correlates with an increased risk of CaOx-related urolithiasis in human cohorts. This study aims to identify the effect of Klotho rs3752472 polymorphism on the renal epithelium injury caused by CaOx. A rat urolithiasis model was established and validated. Renal function was assessed, and histological examination was performed. The distribution and expression of Klotho in the rat model were detected by immunohistochemical staining and western blotting analysis. A renal epithelial cell line (HK2) was used and intervened by COM crystals with several concentrations and time points. Expression of Klotho and key mediators in Wnt/β-catenin pathway were assessed by Western blotting analysis. Wide-type and mutated plasmids of Klotho rs3752472 were added in the cell culture, and the activation of Wnt/β-catenin signaling was tested. Finally, Wide-type and mutated plasmids of Klotho rs3752472 were adoptively transferred to the rat model, and the expression of Klotho was verified. In the rat model, Klotho was mainly distributed in the renal tubular area, which significantly declined in the urolithiasis group. In vitro, COM crystals significantly inhibited the expression of Klotho and induced remarkable renal epithelial cell injury. The mutation of Klotho rs3752472 can notably enhance the expression of Klotho, as well as the protection from renal epithelial cell injury and the inhibition of Wnt/β-catenin signaling pathway. After adoptively transferred to the rat urolithiasis model, similar results were observed for the mutation of Klotho rs3752472. Klotho was significantly correlated with the renal epithelial cell injury induced by CaOx crystals. Furthermore, the mutation of Klotho rs3752472 can remarkably enhance the expression of Klotho in renal tissues and cells, and subsequently protect the renal epithelial cell from the formation of CaOx crystals through the inhibition of Wnt/β-catenin signaling pathway.

Klotho gene polymorphism in renal stone formers from Northwestern India

Klotho gene is an important gene involved in calcium homeostasis, and polymorphisms of this gene may render the individual prone to renal stone formation. We evaluated G395A single nucleotide polymorphisms (SNPs) of Klotho gene at rs1207568 in renal stone patients of North India. This was a prospective study involving 150 patients of renal stone disease (aged 15-60 years) and 100 age- and sex-matched controls. The DNA was isolated and subjected to polymerase chain reaction (PCR) for identifying the G395A Klotho SNPs at rs1207568. Confronting two pair primers were used, and gel electrophoresis showing two bands at 175,252 bp was considered as GG genotype, three bands at 121,175 and 252 bp as GA and two bands at 121 and 252 bp as AA genotype. The association between genotype and cases was evaluated by using Chi-square test and logistic regression analysis. Cases and controls were well matched for age (40.65 vs 42.06, p = 0.063) and sex (p = 0.420). Significantly high proportion of patients with renal stones had GG genotype as compared to controls (odds ratio (OR) 2.37(1.39,4.03), p = 0.001). None of the participants (cases and controls) had homozygous recessive AA genotype. The risk of stone formation was significantly higher in the population carrying G allele {OR 1.94 (1.225-3.073), p 0.004}. Mean serum calcium was higher in stone formers with GG genotype as compared to those with GA genotype (9.16 mg/dl vs 8.91 mg/dl; p = 0.06). GG genotype of G396A Klotho gene SNPs is associated with renal stone formation. The G allele carrier is twice at risk of renal stone formation. The absence of AA genotype in north-western Indian population remains a curiosity.

Genetic factors of polygenic urolithiasis

The article summarizes the findings of Russian and international studies of the genetic aspects of polygenic urolithiasis associated with impairment of calcium metabolism. The article analyzes the genetic risk factors of polygenic nephrolithiasis that show significant association with the disease in case-control studies and Genome-Wide Association Studies (16 genes). We described the gene functions involved in concrement formation in polygenic nephrolithiasis. The modern molecular and genetic technologies (DNA microarray, high-throughput DNA sequencing, etc.) enable identification of the genetic predisposition to a specific disease, realization of the individualized treatment of the patient, and carrying out timely preventive measures among the proband's relatives.

The rs1256328 (ALPL) and rs12654812 (RGS14) Polymorphisms are Associated with Susceptibility to Calcium Nephrolithiasis in a Taiwanese population

Nephrolithiasis is a common disease affecting almost all populations, with an increasing prevalence over the past decades. Previous studies revealed several functional polymorphisms associated with the pathogenesis of nephrolithiasis. However, data on Asian populations are limited. In this study, three candidate polymorphisms were selected from previous studies to investigate the correlations with nephrolithiasis in a Taiwanese population. In total, 454 nephrolithiasis patients were recruited from Kaohsiung Medical University Hospital, with SNP frequency for 1513 subjects of general population from the Taiwan Biobank (TWB) as a genotypic reference. Results revealed that subjects with minor TT genotype at rs1256328 (alkaline phosphatase, liver/bone/kidney (ALPL)) have higher susceptibility to nephrolithiasis (odds ratio (OR) = 2.03, p = 0.0013). In addition, subjects carrying the minor AA genotype at rs12654812 (regulator of G protein signaling 14 (RGS14)) have higher susceptibility to nephrolithiasis (OR = 1.91, p = 0.0017). Among nephrolithiasis patients, subjects with GG at rs7627468 (calcium-sensing receptor (CASR)) have lower pH level in urine (p = 0.0088). Importantly, rs7627468 is associated with the expressions of IQCB1 and EAF2. rs12654812 could influence the expression of RGS14 itself, MXD3, and FGFR4. In summary, this study successfully validated the genetic roles of rs1256328 and rs12654812 in human nephrolithiasis.

FGF23-αKlotho as a paradigm for a kidney-bone network

The vertebrate endoskeleton is not a mere frame for muscle attachment to facilitate locomotion, but is a massive organ integrated with many physiologic functions including mineral and energy metabolism. Mineral balance is maintained by tightly controlled ion fluxes that are external (intestine and kidney) and internal (between bone and other organs), and are regulated and coordinated by many endocrine signals between these organs. The endocrine fibroblast growth factors (FGFs) and Klotho gene families are complex systems that co-evolved with the endoskeleton. In particular, FGF23 and αKlotho which are primarily derived from bone and kidney respectively, are critical in maintaining mineral metabolism where each of these proteins serving highly diverse roles; abound with many unanswered questions regarding their upstream regulation and downstream functions. Genetic lesions of components of this network produce discreet disturbances in many facets of mineral metabolism. One acquired condition with colossal elevations of FGF23 and suppression of αKlotho is chronic kidney disease where multiple organ dysfunction contributes to the morbidity and mortality. However, the single most important group of derangements that encompasses the largest breadth of complications is mineral metabolism disorders. Mineral metabolic disorders in CKD impact negatively and significantly on the progression of renal disease as well as extra-renal complications. Knowledge of the origin, nature, and impact of phosphate, FGF23, and αKlotho derangements is pivotal to understanding the pathophysiology and treatment of CKD.

Genetic Risk Factors for Idiopathic Urolithiasis: A Systematic Review of the Literature and Causal Network Analysis

CONTEXT

Urolithiasis has a high prevalence and recurrence rate. Prevention is key to patient management, but risk stratification is challenging. In particular, genetic predisposition for urinary stones is not fully understood.

OBJECTIVE

To review current evidence of potential causative genes for idiopathic urolithiasis and map their relationships to one another. This evidence is essential for future establishment of molecular targeted therapy.

EVIDENCE ACQUISITION

A systematic literature review from 2007 to 2017 was performed in accordance with the Preferred Reporting Items for Systematic Review and Meta-analyses guidelines. The search was restricted to human studies conducted as either case-control or genome-wide association studies, and published in English. We also performed a causal network analysis of candidate genes gained from the systematic review using Ingenuity Pathway Analysis (IPA).

EVIDENCE SYNTHESIS

During the systematic screening of literature, 30 papers were selected for the review. A total of 20 genes with 42 polymorphisms/variants were found to be associated with urolithiasis risk. Their functional roles were mainly categorized as stone matrix, calcium and phosphate regulation, urinary concentration and constitution, and inflammation/oxidative stress. IPA network analysis revealed that these genes connected via signaling pathways and a proinflammatory/oxidative environment.

CONCLUSIONS

This systematic review provides an updated gene list and novel causal networks for idiopathic urolithiasis risk. Although some genes such as SPP1, CASR, VDR, CLDN14, and SLC34A1 were identified by several studies and recognized by prior reviews, further investigation elucidating their roles in stone formation will be essential for future studies.

PATIENT SUMMARY

In this review, we summarized recent literature regarding genes responsible for kidney stone risk. Based on a detailed review of 30 articles and computational network analysis, we concluded that disorder of mineral regulation with local inflammation in the kidney may cause kidney stone disease.

The impact of klotho gene polymorphisms on urinary tract stone disease

OBJECTIVES

To investigate the effect of klotho gene and β-glucuronidase activity on stone formation in patients with urinary tract stone disease (UTSD).

METHODS

A total of 103 patients with UTSD and 102 controls with no specific urolithiasis history were enrolled into the study. G395A and C1818T polymorphisms of klotho gene were analyzed with PCR method. Serum levels of calcium and phosphorus and 24-h urine levels of β-glucuronidase activity, calcium and phosphorus levels were measured biochemically.

RESULTS

A total of 103 of patients were male (50.2 %) and 102 were female (49.8 %) (p 0.945). Twenty-four-hour urine levels of calcium were significantly higher in UTSD group, whereas no difference was observed in phosphorus levels (p < 0.001, p 0.074, respectively). As for the G395A polymorphism, type of GG was significantly higher in the patient group compared to the controls (p = 0.02), while GA genotype was significantly higher in the controls (p = 0.001). There was no significant difference in F352V and C1818T polymorphism between the patient and control groups. β-glucuronidase activity was slightly lower in the patient group without significance (p 0.932).When patients with GG genotype and the rest were compared, there were no significant difference in all parameters.

CONCLUSIONS

Any polymorphism altering the function of klotho gene may result with stone formation. We found that there are more GG sequences of G395A gene in patients with UTSD. That may be a polymorphism of klotho gene which results with stone formation. Further studies with more patients should be accomplished which are combining the genetic and epigenetic factors associated with urolithiasis and klotho gene to enlighten the etiology of this disease.

The association between KL polymorphism and prostate cancer risk in Korean patients

The Klotho (KL) gene is a classical "aging suppressor" gene. Although recent studies have shown that KL participates in the progression of several types of human cancers, the relationship between KL polymorphism and prostate cancer was unknown. The present study aimed to investigate the association between KL genetic polymorphisms and prostate cancer. Twenty-five common single nucleotide polymorphisms (SNPs) in KL gene (including KL gene polymorphism C1818T in exon 4) were assessed in 272 prostate cancer cases and 173 controls. Single-locus analyses were conducted using unconditional logistic regression. In addition, we did a haplotype analysis for the 25 KL SNPs tested. CC genotype of C1548T KL polymorphism had approximately twofold increased prostate cancer risk compared with the homozygous genotype TT and heterozygote CT (odds ratio 1.85 [95% CI, 1.09-3.12], P = 0.02). We also found that non-T allele carriers had significantly higher prostate cancer risk associated with the prostate cancer clinical characteristics (tumor stage or Gleason score). Our findings suggested that the C1548T polymorphism of KL gene is associated with the prostate cancer and may act as a risk factor for the development of prostate cancer.

Rosiglitazone increases cerebral klotho expression to reverse baroreflex in type 1-like diabetic rats

Reduced baroreflex sensitivity (BRS) is widely observed in diabetic human and animals. Rosiglitazone is one of the clinically used thiazolidinediones (TZD) known as PPARγ agonist. Additionally, the klotho protein produced from choroid plexus in the central nervous system is regulated by PPARγ. In an attempt to develop the new therapeutic strategy, we treated streptozotocin-induced diabetic rats (STZ) with rosiglitazone (STZ + TZD) orally at 10 mg/kg for 7 days. Also, STZ rats were subjected to intracerebroventricular (ICV) infusion of recombinant klotho at a dose of 3 μg/2.5 μL via syringe pump (8 μg/hr) daily for 7 days. The BRS and heart rate variability were then estimated under challenge with a depressor dose of sodium nitroprusside (50 μg/kg) or a pressor dose of phenylephrine (8 μg/kg) through an intravenous injection. Lower expression of klotho in medulla oblongata of diabetic rats was identified. Cerebral infusion of recombinant klotho or oral administration of rosiglitazone reversed BRS in diabetic rats. In conclusion, recovery of the decreased klotho in brain induced by rosiglitazone may restore the impaired BRS in diabetic rats. Thus, rosiglitazone is useful to reverse the reduced BRS through increasing cerebral klotho in diabetic disorders.