Association between Soluble Klotho and Change in Kidney Function: The Health Aging and Body Composition Study

Protective factors as biomarkers and targets for prevention and treatment of diabetic nephropathy: From current human evidence to future possibilities

Although hyperglycemia, high blood pressure and aging increase the risk of developing kidney complications, some diabetes patients exposed to these risk factors do not develop kidney disease, suggesting the presence of endogenous protective factors. There is a growing need to understand these factors determining protection of the kidney in order to improve the design of preventive strategies and to enhance the processes responsible for renoprotection. The aim of this review was to present the existing molecular and epidemiological data on factors showing protective effects in diabetic kidney disease, and to summarize the evidence regarding their potential in the area of future clinical diagnostics, therapeutics and early preventive strategies. These include transcriptomic and proteomic studies regarding the anti-inflammatory, anti-fibrotic and regenerative factors that were associated with slower progression of renal function loss. Another focus is the new evidence regarding the evaluation of alterations in the regulatory epigenome and its involvement in the risk of diabetic kidney disease. Further effort is required to validate and extend these findings, and to define their potential for clinical implementation in the future.

Is multiple tract percutaneous nephrolithotomy a safe approach for staghorn calculi?

PURPOSE

To explore the safety of multiple tract percutaneous nephrolithotomy (PNL) in terms of complication and draw a nomogram to predict the possibility of significant renal function decline (SRFD).

MATERIALS AND METHODS

Patients with complex renal calculi appropriate for PNL at our institution between August 2016 and February 2018 were included in the study. The outcome of single and multiple tract PNL was analyzed retrospectively. A nomogram was created to predict the probability of SRFD.

RESULTS

793 (88.4%) patients were treated with single tract PNL (Group 1) and 104 patients (11.6%) treated with multiple tract PNL (Group 2). Group 2 had a significantly greater hemoglobin reduction (16.0 ± 12.5 vs. 11.4 ± 11.8 g/L, p < 0.001), higher rate of postoperative fever (19.2% vs. 11.9%, p = 0.034) and longer duration of the operation (110.6 ± 39.6 vs. 97.8 ± 34.5 min, p < 0.001). A nomogram for predicting the probability of SRFD was constructed based on identified risk factors: patients' age, positive urine culture (UC +), hemoglobin reduction and embolization. The area of receiver operating characteristic (ROC) curve was 70%. Bootstrapping technique utilized to make the calibration plot showed a high reliability of the nomogram.

CONCLUSIONS

Multiple tract PNL had a higher risk of hemoglobin reduction and postoperative fever than single tract PNL. Multiple tracts had no effect on SRFD, but old age, UC + , hemoglobin reduction and embolization were risk factors for SRFD. A nomogram with the aim of predicting the probability of SRFD based on these parameters demonstrated good uniformity in internal validation.

Soluble Klotho Improves Hepatic Glucose and Lipid Homeostasis in Type 2 Diabetes

Type 2 diabetes (T2D) is one of the most escalating global metabolic diseases, which is highly associated with insulin resistance (IR) and risk of combination with nonalcoholic fatty liver disease (NAFLD). Previous studies suggest that soluble klotho (sKL) could serve as a circulating hormone to mediate energy metabolism, but the detailed mechanism is poorly understood. In this study, we generated T2D models of wild-type (WT), sKL heterozygous (KL ^+/-), and sKL transgenic (TgKL) mice continuously fed a high-fat diet (HFD) and constructed L02 cell lines that stably overexpress sKL to investigate the effect of sKL on hepatic glucose and lipid metabolism. Surprisingly, we discovered that sKL deficiency resulted in exacerbated diabetic phenotypes and hepatic glucolipid metabolism disorders in HFD-fed KL ^+/- diabetic mice (KL ^+/- DM), whereas TgKL diabetic mice (TgKL DM) exhibited ameliorated diabetic phenotypes and decreased IR. Mechanistic studies in vitro and in vivo demonstrated that sKL could inhibit the PI3K/AKT/mTORC1 signaling to upregulate peroxisome proliferator-activated receptor α (PPARα) expression by directly interacting with type 1 insulin-like growth factor receptor (IGF1R) in HFD-fed T2D mice. Thus, sKL could improve hepatic glucolipid homeostasis to ameliorate diabetic phenotypes and lipid accumulation and may function as a potential therapeutic target for the treatment of T2D and reduce the risk of NAFLD.

The prognostic value of soluble Klotho in patients with haemodialysis: a systematic review and meta-analysis

Aim:

The correlation between soluble Klotho (sKlotho) levels and clinical outcomes remains inconclusive for patients undergoing maintenance haemodialysis (MHD). We aimed to evaluate the potential predictive significance of sKlotho in this population by conducting a meta-analysis.

Methods:

PubMed, Embase, Web of Science and Cochrane Library were comprehensively searched for studies concerning the association between sKlotho level and clinical outcomes including cardiovascular (CV) events and all-cause mortality. The pooled hazard ratios (HR) and 95% confidence intervals (CI) were generated using either random or fixed effects models. Sensitivity and subgroup analyses were used to explore heterogeneity sources.

Results:

Eight prospective studies with 992 MHD participants were included and reduced sKlotho levels predicted more adverse outcomes in this meta-analysis. The pooled HRs and 95% CIs related to CV events, mortality, or composite outcomes were 1.73 (95% CI 1.08–2.76, p = 0.02), 2.34 (95% CI 1.34–2.07, p = 0.003) or 1.75 (95% CI 1.19–2.57, p = 0.005). Moderate heterogeneity was observed in the composite adverse outcomes (I² = 57%, p = 0.05). Age and sKlotho level were the main sources of heterogeneities in the subgroup analysis.

Conclusion:

Lower sKlotho levels were associated with more CV events and all-cause mortality, suggesting that sKlotho may have predictive value in CKD patients receiving haemodialysis.

Soluble Klotho, a biomarker and therapeutic strategy to reduce bronchopulmonary dysplasia and pulmonary hypertension in preterm infants

Preterm infants with bronchopulmonary dysplasia (BPD) and pulmonary hypertension (PH) have accelerated lung aging and poor long-term outcomes. Klotho is an antiaging protein that modulates oxidative stress, angiogenesis and fibrosis. Here we test the hypothesis that decreased cord Klotho levels in preterm infants predict increased BPD-PH risk and early Klotho supplementation prevents BPD-like phenotype and PH in rodents exposed to neonatal hyperoxia. In experiment 1, Klotho levels were measured in cord blood of preterm infants who were enrolled in a longitudinal cohort study. In experiment 2, using an experimental BPD-PH model, rat pups exposed to room air or hyperoxia (85% O₂) were randomly assigned to receive every other day injections of recombinant Klotho or placebo. The effect of Klotho on lung structure, PH and cardiac function was assessed. As compared to controls, preterm infants with BPD or BPD-PH had decreased cord Klotho levels. Early Klotho supplementation in neonatal hyperoxia-exposed rodents preserved lung alveolar and vascular structure, attenuated PH, reduced pulmonary vascular remodeling and improved cardiac function. Together, these findings have important implications as they suggest that perinatal Klotho deficiency contributes to BPD-PH risk and strategies that preserve Klotho levels, may improve long-term cardiopulmonary outcomes in preterm infants.

Astaxanthin as a Putative Geroprotector: Molecular Basis and Focus on Brain Aging

In recent years, the scientific interest in natural compounds with geroprotective activities has grown exponentially. Among the various naturally derived molecules, astaxanthin (ASX) represents a highly promising candidate geroprotector. By virtue of the central polyene chain, ASX acts as a scavenger of free radicals in the internal membrane layer and simultaneously controls oxidation on the membrane surface. Moreover, several studies have highlighted ASX’s ability to modulate numerous biological mechanisms at the cellular level, including the modulation of transcription factors and genes directly linked to longevity-related pathways. One of the main relevant evolutionarily-conserved transcription factors modulated by astaxanthin is the forkhead box O3 gene (FOXO3), which has been recognized as a critical controller of cell fate and function. Moreover, FOXO3 is one of only two genes shown to robustly affect human longevity. Due to its tropism in the brain, ASX has recently been studied as a putative neuroprotective molecule capable of delaying or preventing brain aging in different experimental models of brain damage or neurodegenerative diseases. Astaxanthin has been observed to slow down brain aging by increasing brain-derived neurotrophic factor (BDNF) levels in the brain, attenuating oxidative damage to lipids, protein, and DNA and protecting mitochondrial functions. Emerging data now suggest that ASX can modulate Nrf2, FOXO3, Sirt1, and Klotho proteins that are linked to longevity. Together, these mechanisms provide support for a role of ASX as a potential geroneuroprotector.

PTSD and the klotho longevity gene: Evaluation of longitudinal effects on inflammation via DNA methylation

BACKGROUND

Longevity gene klotho (KL) is associated with age-related phenotypes including lifespan, cardiometabolic disorders, cognition, and brain morphology, in part, by conferring protection against inflammation. We hypothesized that the KL/inflammation association might be altered in the presence of psychiatric stress and operate via epigenetic pathways. We examined KL polymorphisms, and their interaction with posttraumatic stress disorder (PTSD) symptoms, in association with KL DNA methylation in blood. We further examined KL DNA methylation as a predictor of longitudinal changes in a peripheral biomarker of inflammation (C-reactive protein; CRP).

METHODS

The sample comprised 309 white non-Hispanic military veterans (93.5 % male; mean age: 32 years, range: 19-65; 30 % PTSD per structured diagnostic interview); 111 were reassessed approximately two years later.

RESULTS

Analyses revealed a methylation quantitative trait locus at rs9527025 (C370S, previously implicated in numerous studies of aging) in association with a Cytosine-phosphate-Guanine site (cg00129557; B = -.65, p =  1.29 X 10^-20), located within a DNase hypersensitivity site in the body of KL. There was also a rs9527025 x PTSD severity interaction (B = .004, p = .035) on methylation at this locus such that the minor allele was associated with reduced cg00129557 methylation in individuals with few or no PTSD symptoms while this effect was attenuated in those with elevated levels of PTSD. Path models revealed that methylation at cg00129557 was inversely associated with CRP over time (B = -.14, p = .005), controlling for baseline CRP. There was also an indirect effect of rs9527025 X PTSD on subsequent CRP via cg00129557 methylation (indirect B = -.002, p = .033).

CONCLUSIONS

Results contribute to our understanding of the epigenetic correlates of inflammation in PTSD and suggest that KL methylation may be a mechanism by which KL genotype confers risk vs. resilience to accelerated aging in those experiencing traumatic stress.

Micturition defects and altered bladder function in the klotho mutant mouse model of aging

INTRODUCTION AND OBJECTIVES

Symptoms associated with detrusor underactivity (DU) or underactive bladder (UAB) can severely impact a person's quality of life, and growing old is the main etiological factor of DU and UAB. The gene Klotho has been associated with suppression of several aging phenotypes, and there is moderate klotho expression in the bladder. Given this, we hypothesized that the klotho gene is involved in regulation of bladder function. Thus, we examined a premature aging rodent genetic model with hypomorphic klotho expression for alterations in bladder function.

METHODS

Klotho mutant mice are established as a preclinical model of aging. Male and female klotho mice had micturition measured at weeks 4, 6, and 8 through metabolic cage and void spot assays. Histology was assessed at 4, 6, and 8 weeks. Lastly, bladder contraction was assessed using bladder strip tissue bath. All animals were gender- and age-matched with wild-type littermates for analysis.

RESULTS

Void spot and bladder contraction assays revealed that klotho mutant mice, similar to other aging models, have increased voiding frequency and decreased voiding volume per micturition event. The in vitro contractile response to electrical stimulation was weaker and muscarinic receptor subtype expression was reduced in the in klotho mutant mouse bladders. These data suggest that klotho mutant mouse bladders had impaired bladder function.

CONCLUSIONS

Klotho mutant mice recapitulate many characteristics of an older dysfunctional bladder, including altered bladder function. Given the short time frame to bladder dysfunction and robustness of the model, this model will provide new insights to drive aging bladder research.

Plasma Soluble αKlotho, Serum Fibroblast Growth Factor 23, and Mobility Disability in Community-Dwelling Older Adults

CONTEXT

αKlotho is a hormone and co-receptor for fibroblast growth factor 23 (FGF23), a hormone that downregulates active vitamin D synthesis and promotes phosphate excretion. Low αKlotho and high FGF23 occur in chronic kidney disease (CKD).

OBJECTIVE

We aimed to assess the relationships of αKlotho and FGF23 with mobility disability in community-dwelling older adults.

DESIGN AND SETTING

We estimated associations of plasma-soluble αKlotho and serum FGF23 concentrations with mobility disability over 6 years. Additional analyses was stratified by CKD.

PARTICIPANTS

Participants included 2751 adults (25.0% with CKD), aged 71 to 80 years, from the 1998 to 1999 Health, Aging, and Body Composition Study visit.

MAIN OUTCOME MEASURES

Walking disability and stair climb disability were defined as self-reported "a lot of difficulty" or an inability to walk a quarter mile and climb 10 stairs, respectively.

RESULTS

Median (interquartile range [IQR]) serum FGF23 and plasma soluble αKlotho concentrations were 46.6 (36.7, 60.2) pg/mL and 630.4 (478.4, 816.0) pg/mL, respectively. After adjustment, higher αKlotho concentrations were associated with lower walking disability rates (Rate Ratio [RR] highest vs. lowest tertile = 0.74; 95% confidence interval l [CI] = 0.62, 0.89; P = 0.003). Higher FGF23 concentrations were associated with higher walking disability rates (RR highest vs. lowest tertile = 1.24; 95%CI = 1.03, 1.50; P = 0.005). Overall, higher αKlotho combined with lower FGF23 was associated with the lowest walking disability rates (P for interaction = 0.023). Stair climb disability findings were inconsistent. No interactions with CKD were statistically significant (P for interaction > 0.10).

CONCLUSIONS

Higher plasma soluble αKlotho and lower serum FGF23 concentrations were associated with lower walking disability rates in community-dwelling older adults, particularly those without CKD.

Positive correlation of serum fibroblast growth factor 23 with peripheral arterial stiffness in kidney transplantation patients

BACKGROUND

Fibroblast growth factor 23 (FGF-23) has a role in arterial stiffness (AS) apart from regulating mineral metabolism. We investigated the association between FGF-23 concentration and peripheral AS in renal transplantation (RT) recipients.

METHODS

The fasting blood samples of RT recipients (n = 66) were collected and analyzed.

RESULTS

A total of 29 (43.9%) RT recipients were classified under the peripheral AS group. The RT recipients in this group had a higher prevalence of diabetes (P < 0.001), hypertension (P = 0.001), and metabolic syndrome (P = 0.023); longer post-RT duration (P = 0.006); higher systolic blood pressure (P < 0.001) and diastolic blood pressure (P = 0.024); and higher fasting glucose (P = 0.002), total cholesterol (P = 0.049), blood urea nitrogen (P = 0.027), phosphorus (P = 0.047), and FGF-23 concentrations (P = 0.003) and FGF-23/α-klotho ratio (P < 0.001) but lower klotho concentrations (P = 0.025) than those in the control group. Moreover, FGF-23 concentration (adjusted odds ratio: 1.057, 95% confidence interval: 1.011-1.105, P = 0.015) was found to be an independent predictor of peripheral AS in RT recipients.

CONCLUSIONS

Serum FGF-23 concentration was a significant predictor of peripheral AS in RT recipients.

Waiting List and Kidney Transplant Vascular Risk: An Ongoing Unmet Concern

BACKGROUND

Chronic kidney disease (CKD) is an important independent risk factor for adverse cardiovascular events in patients waitlisted for kidney transplantation (KT). Although KT reduces cardiovascular risk, these patients still have a higher all-cause and cardiovascular mortality than the general population. This concerning situation is due to a high burden of traditional and nontraditional risk factors as well as uremia-related factors and transplant-specific factors, leading to 2 differentiated processes under the framework of CKD, atherosclerosis and arteriosclerosis. These can be initiated by insults to the vascular endothelial endothelium, leading to vascular calcification (VC) of the tunica media or the tunica intima, which may coexist. Several pathogenic mechanisms such as inflammation-related endothelial dysfunction, mineral metabolism disorders, activation of the renin-angiotensin system, reduction of nitric oxide, lipid disorders, and the fibroblast growth factor 23-klotho axis are involved in the pathogenesis of atherosclerosis and arteriosclerosis, including VC.

SUMMARY

This review focuses on the current understanding of atherosclerosis and arteriosclerosis, both in patients on the waiting list as well as in kidney transplant recipients, emphasizing the cardiovascular risk factors in both populations and the inflammation-related pathogenic mechanisms. Key Message: The importance of cardiovascular risk factors and the pathogenic mechanisms related to inflammation in patients waitlisted for KT and kidney transplant recipients.

The Signaling of Cellular Senescence in Diabetic Nephropathy

Diabetic nephropathy is the leading cause of chronic kidney disease (CKD) in western countries. Notably, it has a rapidly rising prevalence in China. The patients, commonly complicated with cardiovascular diseases and neurologic disorders, are at high risk to progress into end-stage renal disease (ESRD) and death. However, the pathogenic mechanisms of diabetic nephropathy have not been determined. Cellular senescence, which recently has gained broad attention, is thought to be an important player in the onset and development of diabetic nephropathy. In this issue, we generally review the mechanisms of cellular senescence in diabetic nephropathy, which involve telomere attrition, DNA damage, epigenetic alterations, mitochondrial dysfunction, loss of Klotho, Wnt/β-catenin signaling activation, persistent inflammation, and accumulation of uremic toxins. Moreover, we highlight the potential therapeutic targets of cellular senescence in diabetic nephropathy and provide important clues for clinical strategies.

Klotho: A Major Shareholder in Vascular Aging Enterprises

Accelerated vascular aging is a condition that occurs as a complication of several highly prevalent inflammatory conditions such as chronic kidney disease, cancer, HIV infection and diabetes. Age-associated vascular alterations underlie a continuum of expression toward clinically overt cardiovascular disease. This has contributed to the striking epidemiologic transition whereby such noncommunicable diseases have taken center stage as modern-day global epidemics and public health problems. The identification of α-Klotho, a remarkable protein that confers powerful anti-aging properties has stimulated significant interest. In fact, emerging data have provided fundamental rationale for Klotho-based therapeutic intervention for vascular diseases and multiple other potential indications. However, the application of such discoveries in Klotho research remains fragmented due to significant gaps in our molecular understanding of Klotho biology, as well as hurdles in clinical research and experimental barriers that must first be overcome. These advances will be critical to establish the scientific platform from which future Klotho-based interventional trials and therapeutic enterprises can be successfully launched.

The Role of Fibroblast Growth Factor 23 in Inflammation and Anemia

In patients with chronic kidney disease (CKD), adverse outcomes such as systemic inflammation and anemia are contributing pathologies which increase the risks for cardiovascular mortality. Amongst these complications, abnormalities in mineral metabolism and the metabolic milieu are associated with chronic inflammation and iron dysregulation, and fibroblast growth factor 23 (FGF23) is a risk factor in this context. FGF23 is a bone-derived hormone that is essential for regulating vitamin D and phosphate homeostasis. In the early stages of CKD, serum FGF23 levels rise 1000-fold above normal values in an attempt to maintain normal phosphate levels. Despite this compensatory action, clinical CKD studies have demonstrated powerful and dose-dependent associations between FGF23 levels and higher risks for mortality. A prospective pathomechanism coupling elevated serum FGF23 levels with CKD-associated anemia and cardiovascular injury is its strong association with chronic inflammation. In this review, we will examine the current experimental and clinical evidence regarding the role of FGF23 in renal physiology as well as in the pathophysiology of CKD with an emphasis on chronic inflammation and anemia.

The Organ Handling of Soluble Klotho in Humans

BACKGROUND

Chronic kidney disease (CKD) reduces both Klotho expression and its shedding into circulation, an effect that accelerates progression and cardiovascular complications. However, the mechanisms that regulate Klotho release by the human kidney are still unknown.

METHODS

We measured plasma Klotho across the kidney, splanchnic organs and lung in 22 patients (71 ± 2 years, estimated glomerular filtration rate [eGFR] 60 ± 5.4 mL/min 1.73 m2) during elective diagnostic cardiac catheterizations.

RESULTS

Although the Klotho average renal vein concentrations were remarkably higher (by ∼9%) than arterial values, the kidney removed Klotho (or was at zero balance) in 7 subjects, indicating that the kidney contribution to systemic Klotho is not constant. Klotho fractional enrichment across the kidney was inversely related to plasma sodium (r = 0.43, p = 0.045) and acid uric acid levels (r = 0.38, p = 0.084) and directly, to renal oxygen extraction (r = 0.56, p = 0.006). In multivariate analysis, renal oxygen extraction was the only predictor of the enrichment of Klotho across the kidney, suggesting the dependence of renal Klotho release on tubular hypoxia or oxidative metabolism. Klotho balance was neutral across the lung. In patients with eGFR <60 mL/min, Klotho was also removed by splanchnic organs (single pass fractional extraction ∼11%).

CONCLUSIONS

The present study identifies kidney oxygen uptake as a predictor of Klotho release, and splanchnic organs as a site for Klotho removal. This study provides new understanding of kidney Klotho release and suggests that modulating kidney oxygen metabolism could increase Klotho delivery, as an option to slow disease progression and blunt organ damage.

The goddess who spins the thread of life: Klotho, psychiatric stress, and accelerated aging

BACKGROUND

Longevity gene klotho (KL) is associated with age-related phenotypes but has not been evaluated against a direct human biomarker of cellular aging. We examined KL and psychiatric stress, including posttraumatic stress disorder (PTSD), which is thought to potentiate accelerated aging, in association with biomarkers of cellular aging.

METHODS

The sample comprised 309 white, non-Hispanic genotyped veterans with measures of epigenetic age (DNA methylation age), telomere length (n = 252), inflammation (C-reactive protein), psychiatric symptoms, metabolic function, and white matter neural integrity (diffusion tensor imaging; n = 185). Genotyping and DNA methylation were obtained on epi/genome-wide beadchips.

RESULTS

In gene by environment analyses, two KL variants (rs9315202 and rs9563121) interacted with PTSD severity (peak corrected p = 0.044) and sleep disturbance (peak corrected p = 0.034) to predict advanced epigenetic age. KL variant, rs398655, interacted with self-reported pain in association with slowed epigenetic age (corrected p = 0.048). A well-studied protective variant, rs9527025, was associated with slowed epigenetic age (p = 0.046). The peak PTSD interaction term (with rs9315202) also predicted C-reactive protein (p = 0.049), and white matter microstructural integrity in two tracts (corrected ps = 0.005 - 0.035). This SNP evidenced a main effect with an index of metabolic syndrome severity (p = 0.015). Effects were generally accentuated in older subjects.

CONCLUSIONS

Rs9315202 predicted multiple biomarkers of cellular aging such that psychiatric stress was more strongly associated with cellular aging in those with the minor allele. KL genotype may contribute to a synchronized pathological aging response to stress and could be a therapeutic target to alter the pace of cellular aging.

Performance of soluble Klotho assays in clinical samples of kidney disease

Background

Soluble Klotho has multiple systemic salutary effects. In animals, both acute and chronic kidney disease models display systemic Klotho deficiency. As such, there is considerable interest in investigating soluble Klotho as a biomarker in patients with different types and severity of kidney diseases. Unfortunately, there remains uncertainty regarding the best method to measure soluble Klotho in human serum samples.

Methods

Using human serum samples obtained from several clinical cohorts with a wide range of kidney function, we measured soluble Klotho using a commercial enzyme-linked immunosorbent assay (ELISA) as well as with an immunoprecipitation-immunoblot (IP-IB) assay utilizing a synthetic antibody with high affinity and specificity for Klotho. Recovery of spiking with a known amount of exogenous Klotho was tested. A subset of samples was analyzed with and without the addition of a protease inhibitor cocktail at the time of collection or after the first freeze-thaw cycle to determine if these maneuvers influenced performance.

Results

The IP-IB assay was superior to the ELISA at recovery of exogenous Klotho (81-115% versus 60-81%) across the spectrum of kidney function. Klotho measurements by IP-IB were highly correlated with estimated glomerular filtration rate (eGFR) (R = 0.80, P < 0.001) in comparison with the commercial ELISA, which exhibited minimal correlation with eGFR (R = 0.18, P = 0.12). Use of a protease inhibitor cocktail neither improved nor impaired performance of the IP-IB assay; however, subsequent freeze-thaw cycle resulted in a significant reduction in Klotho recovery and dissipated the correlation between Klotho levels and eGFR. With the ELISA, the use of protease inhibitor cocktail resulted in an increase in intrasubject variability.

Conclusions

The IP-IB assay is preferable to the commercial ELISA to measure soluble Klotho concentrations in never-thawed serum samples of humans with varying severity of kidney disease. However, due to the labor-intensive nature of the IP-IB assay, further research is needed to secure an assay suitable for high-throughput work.

The Prognostic Role of Klotho in Patients with Chronic Kidney Disease: A Systematic Review and Meta-analysis

Objective

The prognostic role of Klotho in patients with chronic kidney disease is still controversial. Therefore, we performed this meta-analysis to assess the relationship between the low sKlotho level and the risk of adverse kidney outcomes.

Materials and Methods

We systematically searched medical databases, such as PubMed, Embase, and the Cochrane Library, for eligible publications regarding the relationship between the low sKlotho level and risk of adverse kidney outcomes. The quality of included studies was assessed by using the Newcastle–Ottawa Scale. Combined hazard ratios (HRs) and its 95% confidence intervals (CIs) were calculated using a random- or fixed-effect model. Subgroup analysis was conducted with stratification by age, estimated glomerular filtration rate (eGFR), follow-up interval, region, and study quality. All data was analyzed by RevMan 5.3 analysis software.

Results

Eight cohort studies with 3586 participants from 3818 studies were included in our final analysis. Levels of sKlotho were significantly correlated with the eGFR, with a summary correlation coefficient r and 95% CI of 0.469 (0.226, 0.658). Additionally, low sKlotho levels were strongly associated with increased adverse kidney outcomes, and the pooled HR and its 95% CI were 1.64 (1.19, 2.26; P = 0.002), despite publication bias and statistical heterogeneity (I² = 52%, P = 0.07). Furthermore, this positive correlation was still observed in all of the subgroup analyses. However, heterogeneity was present in subgroup analyses stratified by the eGFR and follow-up interval.

Conclusion

Levels of sKlotho are positively correlated with the eGFR, and low sKlotho levels are significantly associated with an increased risk of poor kidney outcomes. Therefore, sKlotho could be used as a novel biomarker for early diagnosis and prognostic assessment for patients with chronic kidney disease. Studies with a larger sample size and longer follow-up period are warranted to validate our results.

Plasmatic Klotho and FGF23 Levels as Biomarkers of CKD-Associated Cardiac Disease in Type 2 Diabetic Patients

BACKGROUND

Research over the past decade has focused on the role of Klotho as a cardio protective agent that prevents the effects of aging on the heart and reduces the burden of cardiovascular disease CVD. The role of the interaction between fibroblast growth factor 23-(FGF-23)/Klotho in Klotho-mediated actions is still under debate. The main objective was to ascertain the potential use of plasmatic Klotho and FGF23 as markers for CKD-associated cardiac disease and mortality.

METHODS

This was a prospective analysis conducted in an outpatient diabetic nephropathy clinic, enrolling 107 diabetic patients with stage 2⁻3 CKD. Patients were divided into three groups according to their left ventricular mass index and relative wall thickness.

RESULTS

Multinomial regression analysis demonstrated that low Klotho and higher FGF-23 levels were linked to a greater risk of concentric hypertrophy. In the generalized linear model (GLM), Klotho, FGF-23 and cardiac geometry groups were statistically significant as independent variables of cardiovascular hospitalization (p = 0.007). According to the Cox regression model, fatal cardiovascular events were associated with the following cardiac geometric classifications; eccentric hypertrophy (p = 0.050); concentric hypertrophy (p = 0.041), and serum phosphate ≥ 3.6 mg/dL (p = 0.025), FGF-23 ≥ 168 (p = 0.0149), α-klotho < 313 (p = 0.044).

CONCLUSIONS

In our population, Klotho and FGF23 are associated with cardiovascular risk in the early stages of CKD.

Klotho recovery by genistein via promoter histone acetylation and DNA demethylation mitigates renal fibrosis in mice

Renal fibrosis is a common histomorphological feature of renal aging and chronic kidney diseases of all etiologies, and its initiation and progression are substantially influenced by aberrant epigenetic modifications of fibrosis-susceptible genes, yet without effective therapy. "Epigenetic diets" exhibit tissue-protective and epigenetic-modulating properties; however, their anti-renal fibrosis functions and the underlying mechanisms are less understood. In this study, we show that genistein, a phytoestrogenic isoflavone enriched in dietary soy products, exhibits impressive anti-renal fibrosis activities by recovering epigenetic loss of Klotho, a kidney-enriched anti-aging and fibrosis-suppressing protein. Mouse fibrotic kidneys induced by UUO (unilateral ureteral occlusion) displayed severer Klotho suppression and adverse expression of renal fibrosis-associated proteins, but genistein administration markedly recovered the Klotho loss and attenuated renal fibrosis and the protein expression abnormalities. The examination of possible causes of the Klotho recovery revealed that genistein simultaneously inhibited histone 3 deacetylation of Klotho promoter and normalized the promoter DNA hypermethylation by suppressing elevated DNA methyltransferase DNMT1 and DNMT3a. More importantly, genistein's anti-renal fibrosis effects on the renal fibrotic lesions and the abnormal expressions of fibrosis-associated proteins were abrogated when Klotho is knockdown by RNA interferences in UUO mice. Thus, our results identify Klotho restoration via epigenetic histone acetylation and DNA demethylation as a critical mechanism of genistein's anti-fibrosis function and shed new lights on the potentials of epigenetic diets in preventing or treating aging or renal fibrosis-associated kidney diseases. KEY MESSAGES: Genistein prevents renal fibrosis and the associated Klotho suppression in UUO mice. Genistein upregulates Klotho in part by reversing the promoter histone 3 hypoacetylation. Genistein also preserves Klotho via relieving Klotho promoter hypermethylation. Genistein demethylates Klotho promoter by inhibiting aberrant DNMT1/3a expression. Genistein restoration of Klotho is essential for its anti-renal fibrosis function.

Baseline chronic kidney disease does not predict long-term renal functional decline after percutaneous nephrolithotomy

To compare renal functional outcomes in patients with and without chronic kidney disease (CKD) to identify predictors of change in renal function after percutaneous nephrolithotomy (PCNL). We reviewed patients who underwent PCNL by a single surgeon over 3.5 years. Patients' pre- and post-operative Glomerular Filtration Rate (GFR) was calculated. Baseline GFR < 60 ml/min/1.73 m² (stage ≥ 3 CKD) defined our CKD cohort. Patients' baseline renal function, comorbidities, stone parameters, and intra-operative variables were analyzed to determine the relationship with post-operative renal function after PCNL by multivariate analysis. 202 patients were analyzed. Mean follow-up time was 16 months. At baseline, 163 (80.7%) patients were free of CKD and 39 (19.3%) had CKD. Patients without CKD had an overall decrease in GFR from 105.6 to 103.3 ml/min/1.73 m² (p = 0.494). 14/163 (8.6%) non-CKD patients experienced a significant decline in renal function after PCNL; 7/163 (4.3%) developed de novo CKD and 7 had a ≥ 30% decline in GFR. Patients with CKD had an overall increase in mean GFR post-operatively, from 47.3 to 54.0 ml/min/m² (p = 0.067). Two in this cohort (5.1%) experienced a > 30% decline in renal function post-operatively. Age, gender, African American race, presence of comorbidities and pre-operative CKD were not significant predictors of renal function post-operatively on multivariate analysis. PCNL in this cohort appears GFR neutral in the setting of baseline CKD. CKD was not predictive of renal functional decline after PCNL. Given that stone disease carries a high recurrence rate and that CKD is associated with stone formers, further investigation into predictors of renal function change after PCNL is warranted.

Aldosterone induces renal fibrosis by promoting HDAC1 expression, deacetylating H3K9 and inhibiting klotho transcription

Aldosterone has an important role in the progression of renal fibrosis. In the present study, the concentration of aldosterone and klotho (KL) in the serum of patients with chronic kidney disease (CKD) were analyzed. A negative correlation was observed between aldosterone and KL, suggesting that KL may serve a protective role in CKD. Subsequently, an aldosterone‑induced CKD mouse model was established using a single nephrectomy and subcutaneous osmotic pump with aldosterone and 1% high‑salt drinking water. It was demonstrated that fibronectin 1 (Fn1) expression levels were higher in high aldosterone mice, whereas KL expression levels were low. In addition, the results demonstrated that histone deacetylase 1 (HDAC1) protein expression levels were upregulated in the renal distal convoluted tubules of high aldosterone mice, whereas acetylated H3K9 (H3K9Ac) was significantly downregulated. To determine the transcriptional activation status, chromatin immunoprecipitation polymerase chain reaction (PCR) was used to validate binding of H3K9Ac to the KL gene promoter site. It was revealed that the binding product of the KL promoter could be PCR‑amplified at the H3K9Ac site from wild‑type and low aldosterone mice; however, amplification of the binding product was not observed in high aldosterone mice. In conclusion, aldosterone significantly inhibited H3K9 acetylation by upregulating HDAC1 protein expression levels in the renal distal convoluted tubule cells, resulting in its inability to bind to the KL promoter, loss of transcription of the KL gene and increased expression of the renal fibrosis gene, Fn1.

The Biological Role of Klotho Protein in the Development of Cardiovascular Diseases

Klotho is a membrane-bound or soluble antiaging protein, whose protective activity is essential for a proper function of many organs. In 1997, an accidental insertion of a transgene led to creation of transgenic mice with several age-related disorders. In Klotho-deficient mice, the inherited phenotypes closely resemble human aging, while in an animal model of Klotho overexpression, the lifespan is extended. Klotho protein is detected mainly in the kidneys and brain. It is a coreceptor for fibroblast growth factor and hence is involved in maintaining endocrine system homeostasis. Furthermore, an inhibition of insulin/insulin-like growth factor-1 signaling pathway by Klotho regulates oxidative stress and reduces cell death. The association between serum Klotho and the classic risk factors, as well as the clinical history of cardiovascular disease, was also shown. There are a lot of evidences that Klotho deficiency correlates with the occurrence and development of coronary artery disease, atherosclerosis, myocardial infarction, and left ventricular hypertrophy. Therefore, an involvement of Klotho in the signaling pathways and in regulation of a proper cell metabolism could be a crucial factor in the cardiac and vascular protection. It is also well established that Klotho protein enhances the antioxidative response via augmented production of superoxide dismutase and reduced generation of reactive oxygen species. Recent studies have proven an expression of Klotho in cardiomyocytes and its increased expression in stress-related heart injury. Thus, the antioxidative and antiapoptotic activity of Klotho could be considered as the novel protective factor in cardiovascular disease and heart injury.

Distinct patterns of transcriptional and epigenetic alterations characterize acute and chronic kidney injury

Acute kidney injury (AKI) and chronic kidney disease (CKD) are considered early and late phases of a pathologic continuum of interconnected disease states. Although changes in gene expression patterns have recently been elucidated for the transition of AKI to CKD, the epigenetic regulation of key kidney injury related genes remains poorly understood. We used multiplex RT-qPCR, ChIP-qPCR and integrative analysis to compare transcriptional and epigenetic changes at renal disease-associated genes across mouse AKI and CKD models. These studies showed that: (i) there are subsets of genes with distinct transcriptional and epigenetically profiles shared by AKI and CKD but also subsets that are specific to either the early or late stages of renal injury; (ii) differences in expression of a small number of genes is sufficient to distinguish AKI from CKD; (iii) transcription plays a key role in the upregulation of both AKI and CKD genes while post-transcriptional regulation appears to play a more significant role in decreased expression of both AKI and CKD genes; and (iv) subsets of transcriptionally upregulated genes share epigenetic similarities while downregulated genes do not. Collectively, our study suggests that identified common transcriptional and epigenetic profiles of kidney injury loci could be exploited for therapeutic targeting in AKI and CKD.

The Value of Older Donors' Klotho Level in Predicting Recipients' Short-Term Renal Function

BACKGROUND The present organ shortage has led to increased use of kidneys from expanded-criteria donors, but the prognosis is disappointing due to poor graft quality. As a promising kidney protector, the Klotho gene's role in predicting short-term prognosis has not been assessed. MATERIAL AND METHODS We retrospectively analyzed data from 41 recipients and 25 donors. Multiple clinical variables were compared between different subgroups of donors or their corresponding recipients. The area under the receiver operating characteristic curve (AUROC) was used to evaluate the distinguishing ability. Dynamic changes in serum Klotho, FGF-23, and urinary NGAL were assessed. RESULTS Serum Klotho level was significantly lower in donors age ≥50 years (p=0.017), and there was a moderate negative correlation between serum Klotho expression and age (r=-0.464, p=0.019). Moreover, detection of Klotho mRNA and immunohistochemical analysis in kidneys revealed the same trend as in serum. Furthermore, for older donors (age ≥50 years), serum Klotho level had a strong negative correlation with recipient eGFR 1 month post-transplant (r=-0.686, p=0.007), which was proved to be a good predictor for estimating graft function by ROC analysis. Additionally, during the post-transplant follow-up, serum Klotho levels increased slightly after a temporary decline, while serum FGF-23 and urinary NGAL decreased significantly and then stayed low thereafter. CONCLUSIONS Klotho level, which decreases with age, may be a potential predictor of short-term renal function, especially for grafts from older donors.

Rapid decline of kidney function in diabetic kidney disease is associated with high soluble Klotho levels

BACKGROUND

Klotho is found in two forms: a transmembrane form and a soluble form (s-Klotho). In order to be excreted, s-Klotho, that is too large to be filtered, will probably reach the proximal convoluted tubule by a transcytosis process. The aim of our study was to show the relationship between the levels of s-Klotho and tubular injury in patients with diabetic kidney disease (DKD), using as tubular injury marker the kidney injury molecule-1 (KIM-1).

METHODS

Our study included 63 DKD patients (stages 1-5, mean eGFR 65.15±32.45ml/min) with a mean age 58.13±12 years. In all patients we determined serum levels of: KIM-1 and s-Klotho using ELISA, urinary albumin/creatinine ratio (UACR) and reduction in the estimated glomerular filtration rate (eGFR) per year.

RESULTS

We found a strong statistically significant correlation of s-Klotho with the rate of reduction of eGFR/year (r=0.714, p=0.0004) and with the tubular injury marker KIM-1 (r=0.758, p=0.005) and strong correlations of UACR with the rate of reduction of eGFR/year (r=0.53, p<0.01), KIM-1 (r=0.49, p<0.05) and s-Klotho (r=0.52, p<0.01).

CONCLUSION

Despite previous published data, that shows a decrease of s-Klotho in chronic kidney disease, in our study the rapid annual decline of kidney function but not the level of eGFR was associated with increased s-Klotho. A possible explanation could be a more severe proximal tubule injury that could lead to a reduction of tubular excretion of s-Klotho as suggested by the correlation of s-Klotho levels with the serum levels of KIM-1.

Correlation between Soluble α-Klotho and Renal Function in Patients with Chronic Kidney Disease: A Review and Meta-Analysis

Objective

Over decades, numerous inconsistent studies are reported on the relationship between soluble α-Klotho and renal function in patients with chronic kidney disease (CKD). This study aims to perform a meta-analysis to figure out the correlations between soluble α-Klotho and renal function in patients with CKD.

Materials and Methods

We searched medical and scientific literature databases, PubMed and EMBASE (from the inception to October 2017), for publications that reported studies on associations between soluble α-Klotho and renal function in patients with CKD. Only publications in English were extracted. Summary correlation coefficient (r) values were extracted from each study, and 95% confidence intervals (CIs) were calculated. Publication bias was tested, and sensitivity and subgroup analyses were performed to investigate potential heterogeneity.

Results

Of 611 studies, 9 publications with 1457 patients were included into the analysis. The following data were extracted from the literature: first author, year of publication, research region, research index, sample size, average age and Pearson or Spearman correlation coefficient, study design, the αKlotho/FGF23 assays utilized, full length, or the C-terminal fragment of FGF23. The pooled r between α-Klotho and estimated glomerular filtration rate (eGFR), FGF-23 were 0.35 (95%CI, 0.23~0.46, and P<0.05), -0.10 (95%CI, -0.19~-0.01, and P<0.05) with remarkable significance, indicating moderate heterogeneity. There was no significant heterogeneity between subgroups in analyses of α-Klotho and eGFR stratified by research region, mean age, and eGFR, but heterogeneity exists in analyses of α-Klotho and FGF-23 stratified by research region. There was no significant correlation between a-klotho and Ca and PTH and PHOS. There was no evidence of publication bias with Egger's test (p=0.360) or with Begg's test (p=0.902) and the distribution of funnel plots was symmetrical in all of our analysis.

Conclusions

There exists a significant positive correlation between soluble α-Klotho and eGFR in patients with CKD. Also, a significant negative correlation between α-Klotho and FGF23 levels is proven. This raises hope to employ αKlotho and FGF23 as early biomarkers of CKD. However, further large prospective follow-up researches are needed to validate this hypothesis and to explore whether maintaining or elevating the Klotho level could improve renal function and complications in CKD patients.

Klotho and PPAR Gamma Activation Mediate the Renoprotective Effect of Losartan in the 5/6 Nephrectomy Model

Renin angiotensin system (RAS) blockade reduces the progression of chronic kidney disease (CKD) independently of its antihypertensive effect. Ang II-induced fibrosis can be mediated by molecules such as klotho, peroxisome proliferator-activate receptor γ (PPAR-γ), and the Wnt/β-catenin pathway; however, the interaction among these molecules and RAS activation is not completely known. The aim of this study was to investigate a possible link between RAS, PPAR-γ, and Klotho in the 5/6 nephrectomy (NX) animals. NX rats presented hypertension that was blunted by both losartan and propranolol, however, only losartan was able to reduce the expression levels of fibronectin FSP1 and TGF-β in the remnant kidney. The anti-fibrotic Klotho and PPAR-γ were reduced in the remnant kidney, and losartan, but not propranolol, restored their levels. In contrast, the profibrotic Wnt 7a and Wnt 3 were upregulated and losartan prevented the increase in Wnts. In vitro, Ang II induced a decrease in both klotho and in PPAR-γ in Madin-Darby canine kidney (MDCK) cells, and this effect was blunted by losartan. However, klotho expression was increased by pioglitazone, an agonist of PPAR-γ, and suppressed by BADGE, an antagonist of PPAR-γ, suggesting that the effect of Ang II downregulating klotho is mediated by PPAR-γ. These data suggest that activation of the Wnt pathway together with downregulation of PPAR-γ that in turn suppresses klotho contribute to potentiating the profibrotic effect of Ang II.

Association between Urinary Calcium Excretion and Estimated Glomerular Filtration Rate Decline in Patients with Type 2 Diabetes Mellitus: A Retrospective Single-center Observational Study

Urinary calcium excretion is not known to predict progression of renal dysfunction in patients with type 2 diabetes mellitus. This study aimed to investigate associations between urinary calcium excretion and progression of estimated glomerular filtration rate (eGFR) in type 2 diabetic patients. This study was a retrospective, single-center, observational cohort study. We enrolled a total of 89 patients with type 2 diabetes mellitus and the average follow-up period was 7.2 ± 1.0 years. We divided patients into two groups based on the median of annual decline in the slope of eGFR, then defined the over-median population as the progressed group and under-median population as the non-progressed group. Median of annual decline in the slope of eGFR was &minus;1.1 mL/min/1.73 m²/year. Correlation coefficient analysis showed positive correlation of urinary calcium excretion with eGFR (r = 0.39, p < 0.001). Multivariate logistic analysis showed that baseline eGFR and urinary calcium excretion were independent variables for progression of eGFR decline. Urinary calcium excretion could be a useful metabolic parameter for predicting decline in slope of eGFR in patients with type 2 diabetes mellitus.

Reduced Levels of Anti-Ageing Hormone Klotho Predict Renal Function Decline in Type 2 Diabetes

CONTEXT AND OBJECTIVE

Soluble Klotho (sKlotho) is a circulating hormone with cardiovascular-renal protective effects. Whether sKlotho predicts estimated glomerular filtration rate (eGFR) decline in patients with type 2 diabetes mellitus (T2DM) with relatively preserved renal function is unknown.

DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS

Single-center observational follow-up study of 101 patients with T2DM and eGFR >45 mL/min [91% on renin angiotensin system (RAS) blockade] followed for a median of 9 years (range, 2 to 13 years).

MAIN OUTCOME

Primary outcome was a >50% decline in eGFR. sKlotho, serum phosphorus, serum calcium, and fibroblast growth factor-23 levels were measured from stored samples collected at baseline. Patients were followed up with standardized clinical and biochemical measurements.

RESULTS

Patients with residual microalbuminuria (MA) despite RAS blockade (n = 53) had significantly lower levels of sKlotho [median, 184.7 pg/mL; interquartile range (IQR), 130.5 to 271.8 pg/mL) compared with patients without MA (n = 39; median, 235.2 pg/mL; IQR, 172.0 to 289.4 pg/mL; P = 0.03). Of the cohort, 21% reached the primary outcome. In a competing risk analysis, a 10% higher sKlotho level reduced the incidence of the primary outcome by 12% (hazard ratio, 0.27; 95% confidence interval, 0.15 to 0.52; P < 0.001] independent of traditional risk factors. Patients with sKlotho below the median of 204.4 pg/mL had nearly a fourfold higher cumulative incidence of the primary outcome compared with those above the median (24% vs 6.2%; P = 0.01).

CONCLUSIONS

In patients with T2DM with relatively preserved eGFR, reduced levels of sKlotho predict renal function decline independent of traditional risk markers. sKlotho is a biomarker of renal dysfunction and a potential treatment target for renoprotection in T2DM.

The impact of preserved Klotho gene expression on antioxidative stress activity in healthy kidney

Klotho, which was originally identified as an antiaging gene, forms a complex with fibroblast growth factor 23 receptor in the kidney, with subsequent signaling that regulates mineral metabolism. Other biological activities of Klotho, including antiaging effects such as protection from various types of cellular stress, have been shown; however, the precise mechanism of these effects of Klotho gene in the healthy human kidney is not well understood. In this study, we examined the relationships of Klotho and antioxidative stress gene expression levels in zero-hour biopsy specimens from 44 donors in kidney transplantation and verified them in animal models whose Klotho gene expression levels were varied. The nitrotyrosine expression level in the kidney was evaluated in these animal models. Expression levels of Klotho gene were positively correlated with the p53 gene and antioxidant enzyme genes such as catalase, superoxide dismutase 1 (SOD1), SOD2, peroxiredoxin 3 (PRDX3), and glutathione peroxidase 1 (GPX1) but not clinical parameters such as age and renal function or pathological features such as glomerulosclerosis and interstitial fibrosis tubular atrophy. The expression levels of all genes were significantly higher in mice with Klotho overexpression than in wild-type mice, and those except for catalase, PRDX3, and GPX1 were significantly lower in Klotho-deficient mice than in wild-type littermate mice. Nitrotyrosine-positive bands of various sizes were observed in kidney from Klotho-deficient mice only. The preservation of Klotho gene expression might induce the antioxidative stress mechanism for homeostasis of healthy human kidney independently of its general condition, including age, renal function, and histological findings.

Tubular Cell Senescence in the Donated Kidney Predicts Allograft Function, but Not Donor Remnant Kidney Function, in Living Donor Kidney Transplantation

BACKGROUND

It is uncertain whether kidneys from marginal donors are suitable for live kidney transplantation. In deceased donor kidneys, tubular cell senescence affects allograft function. However, the degree of cell senescence in a living donor kidney with marginal factors has not been reported. In this study, we assessed the association of tubular cell senescence with allograft and remnant kidney function by a prospective observational clinical study.

METHODS

Thirty-eight living donor kidney transplantations were analyzed prospectively. Tissue sections obtained from preimplantation kidney biopsies were immunostained for p16INK4a to indicate cell senescence. Various kidney biomarkers were analyzed in urine and blood samples.

RESULTS

Of the 38 donors, 21 had marginal factors. Severe tubular senescence was found in living donors with overlapping marginal criteria. Tubular senescence in living donor kidneys was significantly related to donor age and lower recipient kidney function at 1 year after transplantation independently of donor age (β = -0.281; p = 0.050) but did not affect remnant kidney function after donation. Pretransplantation donor pre-estimated glomerular filtration rate and hypertension did not show a significant area under the curve (AUC) for prediction of high tubular senescence. High plasma levels of soluble αKlotho were associated with a higher predictive value for low tubular cell senescence with an AUC of 0.78 (95% CI 0.62-0.93; p < 0.01).

CONCLUSIONS

The nuclear p16-staining rate in donated kidney tubules is a predictor for allograft kidney function but not donor remnant kidney function. Detection of tubular cell senescence may facilitate selection of appropriate living donor candidates.

Anti-aging factor, serum alpha-Klotho, as a marker of acute physiological stress, and a predictor of ICU mortality, in patients with septic shock

PURPOSE

Genetic deletions decreasing serum alpha-Klotho (alpha-KL) have been associated with rapid aging, multi-organ failure and increased mortality in experimental sepsis. We hypothesized that lower alpha-KL obtained at the onset of septic shock correlates with higher mortality.

MATERIALS AND METHODS

Prospective cohort of 104 adult patients with septic shock. Alpha-KL was measured via ELISA on serum collected on the day of enrollment (within 72h from the onset of shock). Relationship between alpha-KL and clinical outcome measures was evaluated in uni- and multi-variable models.

RESULTS

Median (IQR) alpha-KL was 816 (1020.4) pg/mL and demonstrated a bimodal distribution with two distinct populations, Cohort A [n=97, median alpha-KL 789.3 (767.1)] and Cohort B [n=7, median alpha-KL 4365.1(1374.4), >1.5 IQR greater than Cohort A]. Within Cohort A, ICU non-survivors had significantly higher serum alpha-KL compared to survivors as well as significantly higher APACHE II and SOFA scores, rates of mechanical ventilation, and serum BUN, creatinine, calcium, phosphorus and lactate (all p≤0.05). Serum alpha-KL≥1005, the highest tertile, was an independent predictor of ICU mortality when controlling for co-variates (p=0.028, 95% CI 1.143-11.136).

CONCLUSIONS

Elevated serum alpha-KL in patients with septic shock is independently associated with higher mortality. Further studies are needed to corroborate these findings.

Plasma s-Klotho is related to kidney function and predicts adverse renal outcomes in patients with advanced chronic kidney disease

To investigate whether the soluble Klotho (s-Klotho) level in patients with chronic kidney disease (CKD) is related to kidney function and whether a low s-Klotho level can predict adverse renal outcomes or CKD progression in patients with advanced CKD. 112 patients with CKD stages 3-5 and 30 healthy volunteers were enrolled. Blood samples were collected to measure serum creatinine, calcium, phosphorus, intact parathyroid hormone, and hemoglobin. s-Klotho and fibroblast growth factor 23 (FGF23) were determined by ELISA. We first conducted a cross-sectional study to investigate correlations between s-Klotho and estimated glomerular filtration rate (eGFR) and other parameters. Patients were then followed prospectively for 20.1±10.1 months according to s-Klotho median level until serum creatinine doubled, or initiation of renal replacement therapy, or death. s-Klotho levels inpatients with CKD were significantly lower than that in the control group. For patients with CKD, there were no differences in age distribution among subgroups. However, s-Klotho level differed significantly across CKD stages, and it was lower in the advanced CKD group compared with the moderate CKD group. Correlation analysis revealed that s-Klotho was positively associated with eGFR, but inversely associated with FGF23. During the follow-up of 20.1±10.1 months, patients with higher s-Klotho levels showed a reduced risk of kidney adverse outcomes, including serum creatinine doubling and initiation of renal replacement therapy. Cox regression analysis revealed that low s-Klotho was an independent risk factor for CKD progression. s-Klotho level was closely correlated with kidney function, further, low s-Klotho level could predict adverse kidney disease outcomes in patients with progressive CKD.

Circulating Klotho Associates With Cardiovascular Morbidity and Mortality During Hemodialysis

BACKGROUND

Klotho gene was identified as an aging suppressor. In animals, klotho overexpression extends life span, and defective klotho results in rapid aging and early death. The kidney is the main contributor to circulating klotho levels, and, during chronic kidney disease, renal klotho gene expression is drastically reduced in animals and humans as well.

OBJECTIVE

We aimed to determine the consequences of a serum klotho (seKL) defect on cardiovascular morbidity and mortality during chronic dialysis.

DESIGN

The ARNOGENE study was designed to prospectively follow a cohort of hemodialysis patients for 2 years without specific intervention. A total of 769 patients was recruited and followed from the end of 2008 until January 2011. A total of 238 patients was analyzed due to a technical sample conservation issue with other samples.

RESULTS

The median seKL was markedly reduced, 360.4 ng/L (interquartile range 176.5) as compared with nondialysis chronic kidney disease patients or healthy volunteers. Patients with a seKL above the first quartile (≥280 ng/L) had a significantly reduced occurrence of outcome combining cardiovascular events and cardiovascular death [odds ratio (OR) = 0.39; 0.19 to 0.78, P = 0.008] compared with patient with klotho <280 ng/L. This effect persisted (OR = 0.86; 0.76 to 0.99, P = 0.03) after adjustment on age, sex, diabetes, cardiac insufficiency, dialysis vintage, and serum hemoglobin, albumin, fibroblast growth factor-23, phosphate, and calcium.

CONCLUSIONS

These results suggest that, during chronic hemodialysis, conservation of seKL >280 ng/L is associated with a better 2-year cardiovascular protection. Thus, a preserved klotho function supports cardiovascular protection and may represent a prognostic tool and therapeutic target for cardiovascular disease.