The Klotho proteins in health and disease

The role of endothelin receptor antagonists in kidney disease

Kidney diseases are among the most prevalent conditions worldwide, impacting over 850 million individuals. They are categorized into acute kidney injury and chronic kidney disease. Current preclinical and clinical trials have demonstrated that endothelin (ET) is linked to the onset and progression of kidney disease. In kidney diseases, pathological conditions such as hyperglycemia, acidosis, insulin resistance, and elevated angiotensin II levels lead to an increase in ET. This elevation activates endothelin receptor type A, resulting in harmful effects like proteinuria and a reduced glomerular filtration rate (GFR). Therefore, to slow the progression of kidney disease, endothelin receptor antagonists (ERAs) have been proposed as promising new therapies. Numerous studies have demonstrated the efficacy of ERAs in significantly reducing proteinuria and improving GFR, thereby slowing the progression of kidney diseases. This review discusses the mechanisms of action of ERAs in treating kidney disease, their efficacy and safety in preclinical and clinical studies, and explores future prospects for ERAs.

Nanoparticle-mediated Klotho gene therapy prevents acute kidney injury to chronic kidney disease transition through regulating PPARα signaling in renal tubular epithelial cells

Klotho is an anti-aging protein produced primarily by tubular epithelial cells (TECs). Down-regulated expression of Klotho in injured TECs plays a key pathogenic role in promoting acute kidney injury (AKI) to chronic kidney disease (CKD) transition, yet therapeutic approaches targeting the restoration of renal Klotho levels remain challenging for clinical application. Here, we synthesize polydopamine-polyethylenimine-l-serine-Klotho plasmid nanoparticles (PPSK NPs), which can safely and selectively deliver the Klotho gene to the injured TECs through binding kidney injury molecule-1 and maintain the expression of Klotho protein. In vitro, PPSK NPs effectively reduce the hypoxia-reoxygenation-induced reactive oxygen species production and fibrotic gene expression. In the unilateral ischemia-reperfusion injury- and folic acid-induced AKI-CKD transition mouse models, a single low-dose injection of PPSK NPs is sufficient to preserve the normal kidney architecture and prevent renal fibrosis. Mechanismly, the protective effect of PPSK NPs relies on upregulating a key molecule peroxisome proliferator-activated receptor alpha (PPARα) via the inhibition of p38 and JNK phosphorylation, which in turn improves tubular fatty acid beta-oxidation and reduces renal lipid accumulation, thereby protecting against kidney fibrosis. In conclusion, our results highlight the translational potential of nanoparticle-based Klotho gene therapy in preventing the AKI-CKD transition.

Soluble average Klotho level as a prognostic marker for acute kidney injury outcomes: a 90-day follow-up study

BACKGROUND

Klotho is highly expressed in the kidney and confers pleiotropic kidney protective effects. This study aimed to assess the soluble average Klotho level and its relationship to renal function and outcomes in participants with acute kidney injury (AKI).

METHODS

We recruited 102 participants with AKI and 30 healthy controls (HCs). For patients with AKI, serum soluble (sKlotho) levels upon admission to and discharge from hospital were measured to assess the relationship between sKlotho level and kidney function. Individuals with AKI were followed up for 90 days to determine the association between their average sKlotho level and short-term AKI outcomes.

RESULTS

The baseline sKlotho level in individuals with AKI at admission was significantly lower than that in HCs. For individuals with AKI, the sKlotho level was significantly lower in stage 3 than in stage 1 or 2. The sKlotho level was restored along with renal function improvement at discharge. During follow-up, a lower average, but not baseline, sKlotho level, or average sKlotho/creatinine ration predicted more AKI clinical outcomes.

CONCLUSION

The sKlotho level decreased significantly with kidney injury and represented severity. The average sKlotho level inversely correlated with detrimental kidney outcomes and may have potential diagnostic and predictive roles in AKI.

Klotho in age-related cardiovascular diseases: Insights into mitochondrial dysfunction and cell death

Aging is a major risk factor for the development of cardiovascular diseases (CVD), leading to specific alterations in the heart and vasculature. Besides, the mechanisms and intracellular pathways of aging and the factors affecting it are still not completely clear. Age-related complications such as oxidative stress, decreased autophagy, mitochondrial dysfunction, inflammatory responses, and cardiac dysfunction are associated with relative Klotho deficiency. Klotho, an anti-aging protein, with anti-oxidative and anti-inflammatory properties, has been shown to modulate calcium regulation and autophagy. It also protects against endothelial dysfunction by increasing nitric oxide production. Furthermore, emerging research has revealed that klotho significantly impacts vascular smooth muscle cells (VSMC) energetics and survival. This article has focused on recent advances in using Klotho in age-related CVD and summarizes the pre-clinical evidence supporting this approach. Based on the research, Klotho could provide more therapeutic options for ameliorating aging-related CVD.

Dynamic single cell transcriptomics defines kidney FGF23/KL bioactivity and novel segment-specific inflammatory targets

Fibroblast growth factor 23 (FGF23) via its coreceptor αKlotho (KL) provides critical control of phosphate metabolism, which is altered in both rare and very common syndromes. However, the spatial-temporal mechanisms dictating kidney FGF23 functions remain poorly understood. Thus, developing approaches to modify specific FGF23-dictated pathways has proven problematic. Herein, wild type mice were injected with rFGF23 for one, four and 12h and kidney FGF23 bioactivity was determined at single cell resolution. Computational analysis identified distinct epithelial, endothelial, stromal, and immune cell clusters, with differential expressional analysis uniquely tracking FGF23 bioactivity at each time point. FGF23 actions were sex independent but critically relied upon constitutive KL expression mapped within proximal tubule (segments S1-S3) and distal convoluted tub/connecting tubule cell sub-populations. Temporal KL-dependent FGF23 responses drove unique and transient cellular identities, including genes in key MAPK-signaling and vitamin D-metabolic pathways via early- (transcription factor AP-1-related) and late-phase (initiation factor EIF2 signaling) transcriptional regulons. Combining ATACseq/RNAseq data from a cell line stably expressing KL with the in vivo scRNAseq pinpointed genomic accessibility changes in MAPK-dependent genes, including the identification of FGF23-dependent early growth factor-1 distal enhancers. Finally, we identified unexpected crosstalk between FGF23-mediated MAPK signaling and pro inflammatory TNF receptor activation via transcription factor NF-κB, which blocked FGF23 bioactivity in vitro and in vivo. Collectively, our findings have uncovered novel pathways at the single cell level that likely influence FGF23-dependent disease mechanisms.

Serum Klotho protein level in patients with thyroid dysfunction

OBJECTIVES

This study focused on determining the new marker Klotho and its correlation with other parameters in thyroid dysfunction.

METHODS

Seventy-seven thyroid dysfunction patients were recruited during the period (from Aug 2024 to Dec 2024) with an age range (33-56) years. The patient group was subdivided into two groups: group I (21) Patients with Hyperthyroidism and group II (56) Patients with Hypothyroidism, for comparison, 30 healthy individuals were included as a control. The protein level Klotho was estimated using ELISA. Biochemical parameters; blood urea, creatinine, and lipid profile were measured spectrophotometrically. T3, T4 and TSH were determined using ELFA kit.

RESULTS

Serum levels of Klotho protein were significantly lower (p-value < 0.001) in group I compared to the control group. There was a significant difference (p < 0.001) in the Klotho protein levels in group II compared with the control group. Klotho protein was negatively correlated to TSH, creatinine concentrations, and age. The AUC was excellent with high diagnostic accuracy in differentiating newly diagnosed thyroid dysfunction from the healthy subject group.

CONCLUSIONS

Serum Klotho levels in patients with thyroid dysfunction significantly decreased, particularly in hypothyroidism patients. These levels are inversely correlated with thyroid-stimulating hormone levels and age.

Klotho antiaging protein: molecular mechanisms and therapeutic potential in diseases

Klotho, initially introduced as an anti-aging protein, is expressed in the brain, pancreas, and most prominently in the kidney. The two forms of Klotho (membrane-bound and soluble form) have diverse pharmacological functions such as anti-inflammatory, anti-oxidative, anti-fibrotic, tumour-suppressive etc. The membrane-bound form plays a pivotal role in maintaining kidney homeostasis by regulating fibroblast growth factor 23 (FGF 23) signalling, vitamin D metabolism and phosphate balance. Klotho deficiency has been linked with significantly reduced protection against various kidney pathological phenotypes, including diabetic kidney disease (DKD), which is a major cause of chronic kidney disease leading to end-stage kidney disease. Owing to the pleiotropic actions of klotho, it has shown beneficial effects in DKD by tackling the complex pathophysiology and reducing kidney inflammation, oxidative stress, as well as fibrosis. Moreover, the protective effect of klotho extends beyond DKD in other pathological conditions, including cardiovascular diseases, alzheimer's disease, cancer, inflammatory bowel disease, and liver disease. Therefore, this review summarizes the relationship between Klotho expression and various diseases with a special emphasis on DKD, the distinct mechanisms and the potential of exogenous Klotho supplementation as a therapeutic strategy. Future research into exogenous Klotho could unravel novel treatment avenues for DKD and other diseases.

Klotho senses mechanical stimuli and modulates tension-induced osteogenesis

Delicate external mechanosensing, efficient intracellular mechanotransduction and effective alveolar bone remodeling lay the foundation of orthodontic tooth movement (OTM). Periodontal ligament stem cells (PDLSCs) are thought to be the primary cells that withstand mechanical stimuli and respond to biomechanical signals during orthodontic treatment. Nevertheless, the cellular and molecular mechanisms of orthodontic force-induced mechanosignaling and osteogenesis in PDLSCs still remain unclear. In the present study, we hypothesize that the ageing suppressor, Klotho, is correlated with orthodontic force-triggered mechanical signaling cascades, further contributing to alveolar bone remodeling. This study reveals that Klotho expression is notably upregulated via cytoskeletal-nuclei-mediated epigenetic modifications, consistent with osteogenic differentiation on the tension side during OTM. Additionally, Klotho deficiency undermines tensile force-induced new bone formation in NFκB- and PI3K/Akt-dependent manners. Notably, RNA sequencing (RNA-seq) results and targeted force application experiments unveil that Klotho not only functions as a downstream effector of external stress but also acts as an upstream regulator in mechanical signaling for the first time. In summary, we identify the indispensable role of Klotho in mechanotransduction and alveolar bone formation, which provide a latent target of linking cell senescence to mechanical force in future studies and offer novel insights into orthodontic force-induced tooth movement and bone remodeling.

Fibroblast growth factor receptor signaling in metabolic dysfunction-associated fatty liver disease: Pathogenesis and therapeutic targets

Metabolic dysfunction-associated fatty liver disease (MAFLD) has emerged as a significant hepatic manifestation of metabolic syndrome, with its prevalence increasing globally alongside the epidemics of obesity and diabetes. MAFLD represents a continuum of liver damage, spanning from uncomplicated steatosis to metabolic dysfunction-associated steatohepatitis (MASH). This condition can advance to more severe outcomes, including fibrosis and cirrhosis. Fibroblast growth factor receptors (FGFRs) are a family of four receptor tyrosine kinases (FGFR1-4) that interact with both paracrine and endocrine fibroblast growth factors (FGFs). This interaction activates the phosphorylation of tyrosine kinase residues, thereby triggering downstream signaling pathways, including RAS-MAPK, JAK-STAT, PI3K-AKT, and PLCγ. In the context of MAFLD, paracrine FGF-FGFR signaling is predominantly biased toward the development of liver fibrosis and carcinogenesis. In contrast, endocrine FGF-FGFR signaling is primarily biased toward regulating the metabolism of bile acids, carbohydrates, lipids, and phosphate, as well as maintaining the overall balance of energy metabolism in the body. The interplay between these biased signaling pathways significantly influences the progression of MAFLD. This review explores the critical functions of FGFR signaling in MAFLD from three perspectives: first, it examines the primary roles of FGFRs relative to their structure; second, it summarizes FGFR signaling in hepatic lipid metabolism, elucidating mechanisms underlying the occurrence and progression of MAFLD; finally, it highlights recent advancements in drug development aimed at targeting FGFR signaling for the treatment of MAFLD and its associated diseases.

Dysregulation of Circadian Markers, HAT1 and Associated Epigenetic Proteins, and the Anti-Aging Protein KLOTHO in Placenta of Pregnant Women with Chronic Venous Disease

Background: Chronic venous disease (CVD) is a vascular disorder common among pregnant women, due to the impairment in the venous function associated with the mechanical, hemodynamical, and hormonal changes that occur during pregnancy. CVD is linked to venous hypertension, inflammation, oxidative stress, and hypoxia, which alter placental structure and function, as demonstrated in previous works. The placenta fulfills several roles in fetal development and maternal well-being by mediating nutrient exchange; acting as a mechanical, chemical, and immunological shield; and producing essential hormones, making it crucial to investigate the effects of CVD in this organ. Patients and methods: This work specifically analyzes the gene expression of circadian markers (CLOCK, BMAL1, PER1, and PER2), epigenetic regulators (HAT1 and associated molecules like histones H3, H4, RBBP7, and ASF1), and the anti-aging protein KLOTHO in placental tissue of pregnant women with CVD (CVD-PW, N = 98) compared to healthy pregnant controls (HC-PW, N = 82), using RT-qPCR and immunohistochemistry (IHC) to determine protein expression. Results: Our study demonstrates that the placentas of CVD-PW exhibit the reduced gene and protein levels of circadian regulators (clock, bmal1, per1, and per2), increased expression of hat1 and related proteins (h3, h4, rbbp7, and asf1), and decreased klotho expression, indicative of accelerated aging. Conclusions: These findings highlight profound molecular disturbances in the placentas of women with CVD, offering insights into the disease's pathophysiology and potential implications for maternofetal well-being. While this study deepens our understanding of the relationship between CVD and placental dysfunction, further research is required to fully elucidate these mechanisms and their long-term effects.

Recombinant Klotho administration after myocardial infarction reduces ischaemic injury and arrhythmias by blocking intracellular calcium mishandling and CaMKII activation

Ischaemic heart disease (IHD) remains a major cause of death and morbidity. Klotho is a well-known anti-ageing factor with relevant cardioprotective actions, at least when renal dysfunction is present, but its actions are much less known when renal function is preserved. This study investigated Klotho as a biomarker and potential novel treatment of IHD-associated complications after myocardial infarction (MI) under preserved renal function. Association between circulating Klotho levels and cardiac injury was investigated in patients after ST-elevation MI (STEMI). Biochemical, in vivo and in vitro cardiac function and histological and molecular studies were performed to determine the effect of recombinant Klotho in the failing hearts of mice after MI. We demonstrated that STEMI patients showed lower systemic Klotho levels, with the lowest Klotho tertile in those patients with higher N-terminal pro B-type natriuretic peptide (NT-proBNP) levels. Mice also showed a decrease in systemic Klotho levels after MI induction. Furthermore, recombinant Klotho administration in mice reduced infarct area and attenuated cardiac hypertrophy and fibrosis. We also demonstrated that Klotho treatment prevented reduction in ejection fraction and MI-related ECG changes, including prolonged QRS, JT, QTc, and TpeakTend intervals and premature ventricular contractions. In adult mouse cardiomyocytes, Klotho treatment restricted systolic calcium (Ca2+) release and cell shortening disturbances after MI. Klotho prevented increased diastolic Ca2+ leak and pro-arrhythmogenic events in PMI mice by blocking activation of the Ca2+/calmodulin-dependent kinase type II (CaMKII) pathway, preventing ryanodine receptor type 2 (RyR2) hyperphosphorylation. In conclusion, Klotho supplementation protected against functional and structural cardiac remodelling and ameliorated ventricular arrhythmic events by preventing intracardiomyocyte Ca2+ mishandling in mice following MI. These data uncover a new cardioprotective role of Klotho, emerging as a biomarker of ventricular injury and potential treatment for patients after MI. © 2025 The Author(s). The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Klotho protein: A key modulator of aging and COVID-19 severity

The COVID-19 pandemic has drawn significant attention to factors affecting disease severity, especially in older adults. This study explores the relationship between Klotho, an anti-aging protein, and COVID-19 severity. Conducted at Tehran's Firouzgar Hospital, this case-control study involved 279 participants, assessing serum levels of Klotho, inflammatory markers (C-reactive protein (CRP), Interleukin 6 (IL-6)), and Vitamin D. The findings indicate significantly lower Klotho levels in COVID-19 patients, especially those in the ICU, which correlate with elevated inflammatory markers and reduced Vitamin D levels. This inverse relationship between Klotho levels and disease severity underscores the protein's potential modulatory role in the inflammatory response to COVID-19. The study not only highlights the importance of Klotho as a biomarker for aging and disease severity but also suggests its potential therapeutic value in managing COVID-19, offering a novel perspective on targeting aging-related pathways to mitigate the impact of the disease. These insights open new avenues for research and intervention strategies to leverage anti-aging mechanisms to combat COVID-19 and potentially other age-related diseases.

Association between magnesium depletion score and Klotho levels among U.S. adults: Findings from NHANES 2007-2016

Background

Magnesium is a vital mineral that plays a crucial role in various physiological processes, and its imbalance has been associated with many chronic aging-related diseases. Traditional assessment methods are insufficient, and the Magnesium Depletion Score (MDS) has been proposed as a significant indicator. Klotho, a transmembrane protein, is involved in aging regulation and oxidative stress modulation. Despite the shared relevance of MDS and Klotho to aging, their relationship remains unclear.

Aims

This study aims to investigate the relationship between MDS and Klotho levels in U.S. adults.

Methods

We performed a cross-sectional analysis utilizing information from the NHANES database (2007-2016), including 8285 participants. MDS was computed according to specific criteria, encompassing alcohol intake, proton pump inhibitor utilization, diuretic utilization, and renal function. Participants were categorized into groups according to MDS score: none to low (score = 0 or 1), medium (score = 2), and high (score >2). The association between MDS and Klotho levels was assessed using weighted multivariable linear regression models and subgroup analysis.

Results

The analysis revealed a negative association between MDS and serum Klotho levels after comprehensive adjustment. Participants with the highest MDS showed decreased Klotho concentrations compared to those with the lowest level. This association remained robust even after excluding outliers. Subgroup analysis indicated a stronger correlation between MDS and serum Klotho concentration in individuals aged 40-60 years, women, and those with normal weight.

Conclusion

The findings suggest a negative association between MDS and Klotho levels, indicating that magnesium metabolism may influence Klotho expression. These results underscore the potential significance of magnesium in aging processes and age-related diseases, highlighting the potential benefit of increasing serum Klotho concentration through magnesium supplementation.

Role of Peripheral NLRP3 Inflammasome in Cognitive Impairments: Insights of Non-central Factors

Cognitive impairments are common clinical manifestation of Alzheimer's disease, vascular dementia, type 2 diabetes mellitus, and autoimmune diseases. Emerging evidence has suggested a strong correlation between peripheral chronic inflammation and cognitive impairments. For example, nearly 40% of individuals with inflammatory bowel disease also suffer from cognitive impairments. In this condition, NLRP3 inflammasome (NLRP3-I) generating pro-inflammatory cytokines like IL-1β serves as a significant effector, and its persistence exerts adverse effects to both periphery and the brain. Moreover, investigations on serum biomarkers of mild cognitive impairments have shown NLRP3-I components' upregulation, suggesting the involvement of peripheral inflammasome pathway in this disorder. Here, we systematically reviewed the current knowledge of NLRP3-I in inflammatory disease to uncover its potential role in bridging peripheral chronic inflammation and cognitive impairments. This review summarizes the molecular features and ignition process of NLRP3-I in inflammatory response. Meanwhile, various effects of NLRP3-I involved in peripheral inflammation-associated disease are also reviewed, especially its chronic disturbances to brain homeostasis and cognitive function through routes including gut-brain, liver-brain, and kidney-brain axes. In addition, current promising compounds and their targets relative to NLRP3-I are discussed in the context of cognitive impairments. Through the detailed investigation, this review highlights the critical role of peripheral NLRP3-I in the pathogenesis of cognitive disorders, and offers novel perspectives for developing effective therapeutic interventions for diseases associated with cognitive impairments. The present review outlines the current knowledge on the ignition of NLRP3-I in inflammatory disease and more importantly, emphasizes the role of peripheral NLRP3-I as a causal pathway in the development of cognitive disorders. Although major efforts to restrain cognitive decline are mainly focused on the central nervous system, it has become clear that disturbances from peripheral immune are closely associated with the dysfunctional brain. Therefore, attenuation of these inflammatory changes through inhibiting the NLRP3-I pathway in early inflammatory disease may reduce future risk of cognitive impairments, and in the meantime, considerations on such pathogenesis for combined drug therapy will be required in the clinical evaluation of cognitive disorders.

Association between adult body shape index and serum levels of the anti-aging protein Klotho in adults: a population-based cross-sectional study of the NHANES from 2007 to 2016

Purpose

Adult body shape index (ABSI) is widely recognized as a reliable indicator for evaluating body fat distribution and dysfunction. However, the relationship between ABSI and Klotho protein, known for its anti-aging biological function, has not yet been investigated. Therefore, the aim of this study was to assess the correlation between ABSI and serum Klotho levels in adults residing in the United States.

Methods

A cross-sectional study of participants was conducted based on the 2007-2016 National Health and Nutrition Examination Survey. Visceral adiposity was determined using the ABSI score, and Klotho protein concentration was measured using an enzyme-linked immunosorbent assay kit. Multiple regression models were used to estimate the association between ABSI and Klotho protein after adjusting for several potential confounding variables. Subgroup analysis of ABSI and Klotho was performed using restricted cubic splines.

Result

A total of 11,070 adults were eligible for participation, with a mean ABSI of 8.28 ± 0.45 and a mean Klotho protein concentration of 853.33 ± 309.80 pg/mL. Multivariate regression analysis showed that participants with high ABSI scores had lower serum Klotho protein concentrations. When ABSI was divided into quartiles, after full adjustment, Klotho protein levels were lower in participants in the fourth fully adjusted ABSI quartile (Q4: -0.352 pg/ml) than in those in the lowest quartile (Q1) (P<0.0001).

Conclusion

There was a negative linear correlation between ABSI score and serum Klotho concentration. Higher ABSI was associated with lower serum Klotho concentrations; however, this association did not seem to be significant in subjects with BMI ≥30 kg/m2.Further study is needed to verify the causality of this association and elucidate the underlying mechanisms.

Sex differences in the association between serum α-Klotho levels and hyperlipidemia: a cross-sectional study from NHANES 2013-2016

This study assessed the association between serum α-Klotho levels and hyperlipidemia. The aim was to ascertain the potential of serum α-Klotho levels as a predictive biomarker for hyperlipidemia. The research employed data from the National Health and Nutrition Examination Survey (NHANES) between 2013 and 2016. Weighted logistic regression analyses were employed to investigate the association between serum α-Klotho levels and hyperlipidemia. Restricted cubic spline (RCS) analyses were executed for males and females to scrutinize the non-linear correlation between α-Klotho levels and hyperlipidemia. Subsequently, piecewise logistic regression analysis was carried out based on the RCS findings. In females, the levels of α-Klotho were notably lower in those with hyperlipidemia in comparison to those without this condition (P < 0.05), No significant variation was demonstrated in α-Klotho levels between males with and without hyperlipidemia (P > 0.05). The participants were stratified by sex and subjected to analysis by logistic regression model. When α-Klotho was log2-transformed, it was significantly negatively associated with the risk of hyperlipidemia in females, even after adjusting for all of the covariates (OR 0.45, 95% CI 0.24-0.82), which was not observed in males (OR 1.14, 95% CI 0.63-2.06). The same results were observed in the third tertile of α-Klotho. Moreover, RCS analysis suggested a nonlinear correlation between serum α-Klotho levels and hyperlipidemia in females (P < 0.01). The inflection point of α-Klotho was found to be 1106.87 pg/mL. The piecewise logistic regression model revealed that when α-Klotho levels exceeded 1106.87 pg/mL, the link between α-Klotho and hyperlipidemia was no longer significant (P > 0.05). This investigation highlights the sex-based variation in the link between serum α-Klotho levels and hyperlipidemia. In females, α-Klotho exhibited negative association with hyperlipidemia, displaying a saturation effect. Serum α-Klotho emerges as a promising biological marker for the risk of hyperlipidemia among females.

Current cigarette smoking and decreased serum levels of α-Klotho, an anti-aging hormone, among US adult participants

BACKGROUND AND AIMS

Cigarette smoking is a well-established risk factor for cardiovascular disease and other aging-related disorders; yet the pathogenesis of these diseases induced by smoking remains relatively underexplored. This study was to assess the association between cigarette smoking and serum α-Klotho levels, an anti-aging protein, in US adults.

METHODS AND RESULTS

Data on 4196 participants aged 40-79 years from the 2013-2016 National Health and Nutrition Examination Survey was analyzed for the association using multiple general linear models. Smoking was assessed using both questionnaire data and serum cotinine measurements. Both past and current smokers exhibited significantly lower levels of α-Klotho, with the light smokers exhibiting the lowest levels [geometric mean: 720.85 pg/mL; 95% CI: 662.53, 784.31], compared with non-smokers [806.75 (790.69, 823.13)]. A significantly inverse association between current smoking and α-Klotho levels was revealed. This relationship extended across smoking intensities, with even light smokers displaying the strongest association. After adjusting for potential confounders, light (smoked <5 pack-years), moderate (5-19 pack-years), and heavy smoking (≥20 pack-years) were associated with reductions of 10.81% (-16.91, -4.28), 6.43% (-10.24, -2.47), and 3.38% (-6.83, 0.19) of Klotho levels, respectively, when compared to non-smoking. Active smoking, defined as serum cotinine levels ≥10 ng/mL, was associated with a 4.59% decrease (-6.91, -2.23) in α-Klotho levels.

CONCLUSION

The study demonstrates an inverse relationship between current smoking and serum α-Klotho levels among middle-aged and older adults. Our findings suggest that Klotho may play an important role in smoking-induced diseases. Further investigations are warranted to explore these interactions.

Interaction Effect of Estimated Pulse Wave Velocity and Serum Klotho Level on Chronic Kidney Disease

Objectives

Older individuals usually have greater arterial stiffness, lower serum Klotho levels and a greater incidence of chronic kidney disease (CKD). The current study aimed to evaluate the interaction effect of estimated pulse wave velocity (ePWV) and serum Klotho levels on CKD in Americans.

Methods

Data from the National Health and Nutrition Examination Survey database from 2007 to 2016 were used. Participants with data for the assessment of ePWV and serum Klotho and for the assessment of CKD were enrolled. The associations between ePWV and serum Klotho levels were analyzed via restricted cubic spline analysis and a linear regression model. The associations between exposure factors and CKD prevalence were assessed via a logistic regression model. Subgroup analysis was performed for each confounding factor to assess the robustness of the results.

Results

This study enrolled 13,273 participants, 3859 of whom were CKD patients. CKD patients had higher ePWV (9.66 ± 1.75 m/s vs. 8.48 ± 1.64 m/s, p < 0.001) and lower levels of serum Klotho (816.35 ± 290.47 pg/mL vs. 869.87 ± 315.87 pg/mL, p < 0.001). A significant negative linear association was found between ePWV and serum Klotho. According to the fully adjusted model, a significant interaction effect between ePWV and serum Klotho was observed on the risk of CKD (p < 0.001). Compared with individuals with a lower ePWV and higher serum Klotho, individuals with an increased ePWV and lower serum Klotho had a significantly elevated risk of CKD (OR: 1.847, 95% confidence interval: 1.467-2.325; p < 0.001). The subgroup analysis revealed that the results were robust.

Conclusions

The study demonstrated significant interaction effect of ePWV and serum Klotho on the prevalence of CKD. Individuals with increased ePWV and decreased serum Klotho levels had the highest risk of CKD. The assessment of the combination of ePWV and serum Klotho for CKD management should be considered routine in clinical practice.

Rejuvenation Modulation of Nucleus Pulposus Progenitor Cells Reverses Senescence-Associated Intervertebral Disc Degeneration

The decreased regeneration potential of aging nucleus pulposus resident progenitor cells (NPPCs) fails to resist intervertebral disc degeneration (IVDD), and strategies to remodel the regeneration capacity of senescent NPPC are urgently needed. A decrease in Klotho gene expression in NPPCs of both old mice and humans exacerbates the impaired regenerative functionality of NPPC. Here, an NPPC-targeted lipid thymine nanoparticle (NT-LNP) is reported for the in situ manipulation of the regenerative repair potential of NPPCs, restoration of degenerated nucleus pulposus tissue, and mitigation of IVDD. Specifically, the results showed that the in-house customized lipid nanoparticles efficiently introduced Klotho circular ribonucleic acid (circRNA) into NPPCs to engender a renascent phenotype and tuned the balance of extracellular matrix synthesis/catabolism in vitro and in vivo. Moreover, an intradiscal injectable hydrogel system that scavenges chemokines (MCP1 and IL8) in tandem with NPPCs rejuvenated NT-LNPs in the IVD, modulating the inflammatory environment and synergistically promoting the regeneration of degenerated intervertebral discs. In summary, the findings establish that NPPCs can be re-engineered to be youthful and pluripotent to maintain homeostasis and rejuvenation, thereby providing a reversible treatment strategy for IVDD with broad application in other senescence-related diseases.

Site-specific analysis and functional characterization of N-linked glycosylation for β-Klotho protein

β-Klotho (KLB), a type I transmembrane protein, serves as an obligate co-receptor determining the tissue-specific actions of endocrine fibroblast growth factors (FGFs). Despite accumulative evidence suggesting the occurrence of N-glycosylation in the KLB protein, the precise N-glycosites, glycoforms, and the impacts of N-glycosylation on the expression and function of the KLB protein remain unexplored. Employing a mass spectrometry-based approach, a total of 12 N-glycosites displaying heterogeneous site occupancy and glycoforms were identified within the extracellular region of the recombinant human KLB protein. Molecular simulation revealed negligible impact of these N-glycans on the overall structure of the KLB protein. However, both pharmacological inhibition of N-glycosylation and mutagenesis targeting N-glycosites reduced mature KLB protein content without impacting KLB mRNA synthesis in cells, underscoring the critical role of N-glycosylation in maintaining the stability of the KLB protein. Further studies revealed that the underglycosylated KLB mutant underwent rapid degradation via both lysosomal and proteasomal pathways and was unable to be efficiently trafficked to the plasma membrane, leading to impaired FGF21 signaling transduction. Collectively, multisite N-glycosylation is essential for the stability and cell surface localization of the KLB protein, representing a novel modulatory mechanism of endocrine FGF signaling.

Pathophysiology of vascular ageing and the effect of novel cardio-renal protective medications in preventing progression of chronic kidney disease in people living with diabetes

AIM

Among people with diabetes those with chronic kidney disease (CKD) have a reduced life expectancy with increased risk of cardiovascular disease (CVD) a major contributor to morbidity and mortality. CKD related to diabetes is growing worldwide and is one of the leading causes of kidney failure globally. Diabetes is associated with accelerated vascular ageing and the related mechanisms and mediators that drive the progression of CKD and CVD disease in people with diabetes may help provide insights into the pathophysiology of cardio-renal complications and guide treatment interventions in people with diabetes.

METHODS

We conducted a narrative review of the literature using PubMed for English language articles that contained keywords that related to diabetes, chronic or diabetic kidney disease, ageing, cellular senescence, arterial stiffness, Klotho and sirtuins, sodium-glucose co-transporter-2 (SGLT-2) inhibitors, renin angiotensin aldosterone system (RAAS) and glucagon-like peptide-1 (GLP-1) receptor agonists.

RESULTS

Progressive kidney disease in diabetes is associated with accelerated ageing driven in part by multiple processes such as cellular senescence, inflammation, oxidative stress and circulating uremic toxins. This accelerated ageing phenotype contributes to increased arterial stiffness, endothelial dysfunction, cognitive decline and muscle wasting, thereby elevating morbidity and mortality in individuals with diabetes and CKD. Deficiency of the kidney-derived anti-ageing hormone Klotho and reduced sirtuin levels play pivotal roles in these ageing pathways. Dietary, lifestyle and pharmacological interventions targeting vascular ageing may help reduce the progression of CKD and associated CVD in people with diabetes. The current standard of care and pillars of treatment for kidney disease such as RAAS inhibitors, SGLT-2 inhibitors and GLP-1 receptor agonists all influence pathways involved in vascular ageing.

CONCLUSIONS

A multifactorial intervention to prevent the development of CKD by targeting traditional risk factors as well as treatment with novel agents with cardio-renal beneficial effects can prevent accelerated ageing and extend lifespan in people with diabetes.

Klotho Is Cardioprotective in the mdx Mouse Model of Duchenne Muscular Dystrophy

Duchenne muscular dystrophy (DMD) is a lethal, progressive skeletal and cardiac myopathy. Cardiomyopathy is the leading cause of death in patients with DMD, but the molecular basis for heart failure is incompletely understood. As with humans, in the mdx mouse model of DMD, cardiac function is impaired after the onset of skeletal muscle pathology. Dysregulation of Klotho gene regulation in dystrophic skeletal muscles occurs at disease onset, affecting pathogenesis. Whether Klotho is protective against dystrophin-deficient cardiomyopathy is unknown. This study found that expression of a Klotho transgene prevented deficits in left ventricular ejection fraction and fractional shortening in mdx mice. Improvements in cardiac performance were associated with reductions in adverse cardiac remodeling, cardiac myocyte hypertrophy, and fibrosis. In addition, mdx mice expressed high concentrations of plasma fibroblast growth factor 23 (FGF23), and expression was increased locally in hearts. The cardioprotective effects of Klotho were not associated with differences in renal function or serum biochemistries, but transgene expression prevented increased expression of plasma FGF23 and cardiac Fgf23 mRNA expression. Cardiac reactive oxygen species, oxidative damage, mitochondrial damage, and apoptosis were reduced in transgenic hearts. Our findings also showed that FGF23 stimulates hypertrophic growth in dystrophic neonatal mouse ventricular myocytes in vitro, which was inhibited by co-stimulation with soluble Klotho. Taken together, these results show that Klotho prevented dystrophic cardiac remodeling and improved function.

The Impact of Klotho in Cancer: From Development and Progression to Therapeutic Potential

Klotho, initially identified as an anti-aging gene, has been shown to play significant roles in cancer biology. Alongside α-Klotho, the β-Klotho and γ-Klotho isoforms have also been studied; these studies showed that Klotho functions as a potential tumor suppressor in many different cancers by inhibiting cancer cell proliferation, inducing apoptosis and modulating critical signaling pathways such as the Wnt/β-catenin and PI3K/Akt pathways. In cancers such as breast cancer, colorectal cancer, hepatocellular carcinoma, ovarian cancer, and renal cell carcinoma, reduced Klotho expression often correlates with a poor prognosis. In addition, Klotho's role in enhancing chemotherapy sensitivity and its epigenetic regulation further underscores its potential as a target for cancer treatments. This review details Klotho's multifaceted contributions to cancer suppression and its potential as a therapeutic target, enhancing the understanding of its significance in cancer treatment and prognoses.

Predictive value of circulating fibroblast growth factor-23 and Klotho on protein-energy wasting in patients undergoing hemodialysis

Background

As a state of metabolic and nutritional derangements, protein-energy wasting (PEW) is highly prevalent and associated with increased morbidity and mortality in hemodialysis patients. Fibroblast growth factor-23 (FGF-23) and Klotho have been proven to contribute to chronic kidney disease-mineral and bone disorder (CKD-MBD) in patients undergoing hemodialysis. Previous evidence suggested that FGF-23 and Klotho may also contribute to the malnutritional status among these patients; however, the inter-relationship between the FGF-23-Klotho axis and PEW remains unclear. Therefore, we conducted this cross-sectional study to evaluate the association between plasma FGF-23 and Klotho levels and PEW in hemodialysis patients and to explore whether these markers could predict the presence of PEW.

Methods

Plasma concentrations of FGF-23 and Klotho were measured, and their associations with PEW were assessed. PEW was evaluated based on body weight, muscle mass, biochemical data, and protein and energy intake, according to the 2008 criteria from the International Society of Renal Nutrition and Metabolism (ISRNM).

Results

In this study, 147 hemodialysis patients (mean age 61.05 ± 13.32 years) were enrolled, of whom 66 (44.90%) had PEW. PEW was significant positively correlated with FGF-23 (r = 0.403, p < 0.001), age (r = 0.225, p = 0.006), C-reactive protein (r = 0.236, p = 0.004), intact parathyroid hormone (r = 0.237, p = 0.004), and single-pool Kt/V (r = 0.170, p = 0.040), while it was negatively correlated with Klotho (r = -0.361, p < 0.001), hemoglobin (r = -0.215, p = 0.009), and serum creatinine (r = -0.278, p = 0.001). Logistic regression analyses showed that plasma FGF-23 and Klotho were independently associated with PEW, even after adjusting for covariables. The area under the ROC curve (AUC) of FGF-23 and Klotho in predicting PEW was 0.734 and 0.710 (p < 0.001), respectively. When the combination of FGF-23 and Klotho was used to predict PEW, its sensitivity was 81.8%, specificity was 60.5%, and the AUC was 0.746.

Conclusion

Plasma levels of FGF-23 and Klotho are associated with PEW in hemodialysis patients. Higher plasma FGF-23 levels and lower Klotho levels may serve as valuable predictors of PEW in these patients.

Serum protein α-klotho mediates the association between lead, mercury, and kidney function in middle-aged and elderly populations

BACKGROUND

Heavy metals are significant risk factors for kidney function. Numerous studies have shown that exposure to heavy metals negatively correlates with kidney function through oxidative stress pathways, and serum α-klotho is linked to oxidative stress. However, the role of α-klotho in the relationship between blood lead, mercury, and kidney function remains unclear.

METHOD

This study evaluated the mediating role of alpha-klotho in the relationship between lead, mercury and renal function, using data from the 2007-2016 National Health and Nutrition Examination Survey (NHANES) in U.S. adults aged 40-79. The sample included 11,032 participants, with blood lead, mercury, α-klotho, and other relevant covariates measured. Inductively coupled plasma mass spectrometry was used to assess blood lead and mercury levels, and enzyme-linked immunosorbent assay (ELISA) was employed to measure serum α-klotho. Kidney function was evaluated using estimated glomerular filtration rate (eGFR) based on creatinine levels. Multivariable linear regression was conducted to analyze the relationships between blood lead, mercury, α-klotho, and eGFR. A mediation analysis model was used to assess whether α-klotho influenced these associations.

RESULTS

We observed a significant association between blood lead and eGFR. Mediation analysis revealed that α-klotho accounted for 12.76% of the relationship between serum lead and eGFR in the NHANES population. Subgroup analysis showed that α-klotho mediated 12.43%, 6.87%, 21.50% and 5.44% of the relationship between blood lead and eGFR in women, middle-aged adults (40-59 years old), without cardiovascular disease and hypertension, respectively. However, α-klotho did not mediate the relationship between blood mercury and eGFR in terms of gender or age. This newly identified pathway may provide valuable insights for the prevention and treatment mechanisms related to kidney function impairment.

CONCLUSION

We found that blood lead was associated with renal function. According to the results of subgroup analysis, for blood lead, serum α-klotho mediated the association in females, middle aged 60-79 years. The relationship between blood mercury and renal function was not clinically significant, and serum α-Klotho mediated the relationship between blood mercury and renal function without significant clinical significance.

Unveiling the Emerging Role of Klotho: A Comprehensive Narrative Review of an Anti-aging Factor in Human Fertility

Klotho, an anti-aging protein, plays a vital role in diverse biological functions, such as regulating calcium and vitamin D levels, preventing chronic fibrosis, acting as an antioxidant and anti-inflammatory agent, safeguarding against cardiovascular and neurodegenerative conditions, as well as exerting anti-apoptotic, anti-senescence effects. Additionally, it contributes to metabolic processes associated with diabetes and exhibits anti-cancer properties. This protein is commonly expressed in organs, such as kidneys, brain, pancreas, parathyroid glands, ovaries, and testes. Recent research has highlighted its significance in human fertility. This narrative review provides insight into the involvement of Klotho protein in male and female fertility, as well as its potential role in managing human infertility in the future. In this study, a search was conducted on literature spanning from November 1997 to June 2024 across multiple databases, including PUBMED, SCOPUS, and Google Scholar, focusing on Klotho proteins. The search utilized keywords, such as "discovery of Klotho proteins," "Biological functions of Klotho," "Klotho in female fertility," "Klotho and PCOS," "Klotho and cryopreservation," and "Klotho in male infertility." Inclusion criteria comprised full-length original or review articles, as well as abstracts, discussing the role of Klotho protein in human fertility, published in English in various peer-reviewed journals. Exclusion criteria involved articles published in languages other than English. Hence, due to its anti-aging characteristics, Klotho protein presents potential roles in male and female fertility and holds promising prospects for reproductive medicine. Further, it holds the potential to become a valuable asset in addressing infertility concerns for both males and females.

GLP-1 Receptor Agonists Alleviate Diabetic Kidney Injury via β-Klotho-Mediated Ferroptosis Inhibition

Semaglutide (Smg), a GLP-1 receptor agonist (GLP-1RA), shows renal protective effects in patients with diabetic kidney disease (DKD). However, the exact underlying mechanism remains elusive. This study employs transcriptome sequencing and identifies β-Klotho (KLB) as the critical target responsible for the role of Smg in kidney protection. Smg treatment alleviates diabetic kidney injury by inhibiting ferroptosis in patients, animal models, and HK-2 cells. Notably, Smg treatment significantly increases the mRNA expression of KLB through the activation of the cyclic adenosine monophosphate (cAMP) signaling pathway, specifically through the phosphorylation of protein kinase A (PKA) and cAMP-response element-binding protein (CREB). Subsequently, the adenosine monophosphate-activated protein kinase (AMPK) signaling pathway is activated, reprograming the key metabolic processes of ferroptosis such as iron metabolism, fatty acid synthesis, and the antioxidant response against lipid peroxidation. Suppression of ferroptosis by Smg further attenuates renal inflammation and fibrosis. This work highlights the potential of GLP-1RAs and KLB targeting as promising therapeutic approaches for DKD management.

Estimated Proximal Tubule Fluid Phosphate Concentration and Renal Tubular Damage Biomarkers in Early Stages of Chronic Kidney Disease

OBJECTIVE

An increase in proximal tubule fluid phosphate concentration is caused by increased serum fibroblast growth factor-23 (FGF23) levels, which resulted in renal tubular damage in a mouse model of chronic kidney disease (CKD). However, few human studies have supported this concept. This study aimed to explore the association among estimated proximal tubule fluid phosphate concentration (ePTFp), serum FGF23 levels, and renal tubular damage biomarkers in middle-aged and older populations with mild decline in renal function.

METHODS

This cross-sectional study included 218 participants aged ≥45 with CKD stages G2-G4. Anthropometric measurements, blood tests, spot urine biomarkers, renal ultrasonography, cardiovascular assessment, smoking status, and medication usage were obtained in the morning in fasted states. The ePTFp was calculated using serum creatinine, urine phosphate, and creatinine concentrations. Urinary β2-microglobulin (β2-MG) and liver-type fatty acid-binding protein (L-FABP) levels were evaluated to assess renal tubular damage.

RESULTS

PTFp, serum FGF23, urinary β2-MG, and urinary L-FABP levels increased with CKD stage progression (stages G2, G3, and G4). However, serum and urine phosphate concentrations were comparable across the CKD stages. Univariate analysis revealed a stronger correlation of ePTFp with serum FGF23, urinary β2-MG, and urinary L-FABP levels than with the corresponding serum and urine phosphate concentrations. Multivariate analyses demonstrated that increased ePTFp was independently associated with elevated serum FGF23 and urinary β2-MG levels, even after adjusting for potential covariates, including the estimated glomerular filtration rate and urinary albumin-to-creatinine ratio.

CONCLUSIONS

Our results are consistent with the concept in mouse model and suggest that increased ePTFp are associated with increased serum FGF23 levels and renal tubular damage during the early stages of CKD.

Clemastine mitigates sepsis-induced acute kidney injury in rats; the role of α-Klotho/TLR-4/MYD-88/NF-κB/ Caspase-3/ p-P38 MAPK signaling pathways

Sepsis is a fatal condition, with an annual incidence of more than 48 million cases as well as 11 million deaths resulting from it. Moreover, sepsis continues to rank as the fifth most prevalent cause of mortality globally. The objective of this study is to investigate if Clemastine (CLM) pretreatment protects against acute kidney injury (AKI) caused by cecal ligation and puncture (CLP) via modulating Toll-like receptor-4 (TLR-4), Myeloid differentiation primary response 88 (MYD-88), nuclear factor kappa B (NF-κB), Bcl-2-associated X (Bax), B-cell lymphoma-2 (Bcl-2), and caspase-3 signaling pathways. CLM markedly attenuated sepsis-caused molecular, biochemical, and histopathological alterations. CLM downregulated the levels of the proinflammatory markers, suppressed the expression of cleaved caspase-3, TLR-4 and MYD-88 as well as inactivating NF-κB p-P65 and p-P38 proteins, inhibited Bax, NF-κB, and caspase-3 genes expression, and augmented α-Klotho protein expression as well as Bcl-2 gene expression. Finally, CLM pretreatment protected against acute kidney injury by preventing TLR-4/p-P38 pathway-mediated apoptotic cell death in rats.

The Complexity and Significance of Fibroblast Growth Factor (FGF) Signaling for FGF-Targeted Cancer Therapies

Fibroblast growth factors (FGFs) have diverse functions in the regulation of cell proliferation and differentiation in development, tissue maintenance, wound repair, and angiogenesis. The goal of this review paper is to (i) deliberate on the role of FGFs and FGF receptors (FGFRs) in different cancers, (ii) present advances in FGF-targeted cancer therapies, and (iii) explore cell signaling mechanisms that explain how FGF expression becomes dysregulated during cancer development. FGF is often mutated and overexpressed in cancer and the different FGF and FGFR isoforms have unique expression patterns and distinct roles in different cancers. Among the FGF members, the FGF 15/19 subfamily is particularly interesting because of its unique protein structure and role in endocrine function. The abnormal expression of FGFs in different cancer types (breast, colorectal, hepatobiliary, bronchogenic, and others) is examined and correlated with patient prognosis. The classification of FGF ligands based on their mode of action, whether autocrine, paracrine, endocrine, or intracrine, is illustrated, and an analysis of the binding specificity of FGFs to FGFRs is also provided. Moreover, the latest advances in cancer therapeutic strategies involving small molecules, ligand traps, and monoclonal antibody-based FGF inhibitors are presented. Lastly, we discuss how the dysregulation of FGF and FGFR expression affects FGF signaling and its role in cancer development.

Molecular and Cellular Mechanisms of Immunosenescence: Modulation Through Interventions and Lifestyle Changes

Immunosenescence, the age-related decline in immune function, is a complex biological process with profound implications for health and longevity. This phenomenon, characterized by alterations in both innate and adaptive immunity, increases susceptibility to infections, reduces vaccine efficacy, and contributes to the development of age-related diseases. At the cellular level, immunosenescence manifests as decreased production of naive T and B cells, accumulation of memory and senescent cells, thymic involution, and dysregulated cytokine production. Recent advances in molecular biology have shed light on the underlying mechanisms of immunosenescence, including telomere attrition, epigenetic alterations, mitochondrial dysfunction, and changes in key signaling pathways such as NF-κB and mTOR. These molecular changes lead to functional impairments in various immune cell types, altering their proliferative capacity, differentiation, and effector functions. Emerging research suggests that lifestyle factors may modulate the rate and extent of immunosenescence at both cellular and molecular levels. Physical activity, nutrition, stress management, and sleep patterns have been shown to influence immune cell function, inflammatory markers, and oxidative stress in older adults. This review provides a comprehensive analysis of the molecular and cellular mechanisms underlying immunosenescence and explores how lifestyle interventions may impact these processes. We will examine the current understanding of immunosenescence at the genomic, epigenomic, and proteomic levels, and discuss how various lifestyle factors can potentially mitigate or partially reverse aspects of immune aging. By integrating recent findings from immunology, gerontology, and molecular biology, we aim to elucidate the intricate interplay between lifestyle and immune aging at the molecular level, potentially informing future strategies for maintaining immune competence in aging populations.

Nonlinear relationship between serum Klotho and chronic kidney disease in US adults with metabolic syndrome

Background

Current evidence regarding the effects of serum Klotho among patients with metabolic syndrome (MetS) is scarce. This study explored the relationship between serum Klotho levels and the odds of chronic kidney disease (CKD) in middle-aged and older populations with MetS.

Materials and methods

This cross-sectional study analyzed data from 4870 adults aged 40-79 years who participated in the National Health and Nutrition Survey (NHANES) from 2007 to 2016. CKD was identified at urinary albumin to creatinine ratio (UACR) of 30 mg/g or higher and/or an estimated glomerular filtration rate (eGFR) below 60 mL/min/1.73 m2. Measurement of serum Klotho concentration was determined via enzyme-linked immunosorbent assay (ELISA) and subsequently divided into four quartiles (Q1-Q4). The NHANES criteria were followed in calculating the sampling weights. Multivariable logistic regression models were employed to assess the correlation between Klotho and CKD, while generalized linear models with cubic spline functions and smooth curve fitting were utilized to detect any nonlinear relationship. Additionally, subgroup analysis and a range of sensitivity analyzes were conducted.

Results

Results showed that a nonlinear L-shaped relationship existed between serum Klotho levels and CKD risk, with the lowest prevalence observed at 9.63-9.94 pg/mL Klotho concentrations. With a two-segment linear regression model, an inflection point of 9.88 pg/mL was noted. Hypertension status was identified as an interaction mediator (P interaction = 0.006). Sensitivity analysis showed stable results.

Conclusions

A nonlinear L-shaped relationship exists between serum Klotho levels and risks of CKD among middle-aged and older adults with MetS, with the lowest prevalence observed at 9.63 to 9.94 pg/mL Klotho concentrations. Our findings, if replicated, underscore the need to estimate the optimal serum Klotho concentrations and the consequential inverse relationship, thus implying the potential of Klotho as both a serum biomarker and a possible preventive or therapeutic intervention.

Fasting recovers age-related hypertension in the rats: reset of renal renin-angiotensin system components and klotho

BACKGROUND

The renal renin-angiotensin system (RAS) plays a vital part in the control of blood pressure and is known to be affected by aging. This study aimed to investigate the effects of intermittent fasting on age-related hypertension and the expression of local renal RAS components.

METHODS

The Wistar rats were categorized into three main age groups (young, middle aged, and elderly) and three dietary treatment models, including ad libitum feeding (AL), every other day fasting (EOD), and one day per week of fasting (FW). After three months, blood pressure (BP) was assessed. Some genes and proteins of the renal RAS system were measured by using Real time PCR and Western blot. α-klotho and Ang II proteins were assessed by ELISA method.

RESULTS

Old rats exhibited significantly increase in BP and Ang II (P < 0.001 vs. young rats) and a significant reduction in circulating levels of α-klotho and kidney AT2R protein (P < 0.001, P < 0.01, vs. young rats, respectively). Additionally, they respond to aging by increasing the AT1aR/AT2R proteins ratio (P < 0.05). Two model of feeding reduced BP in old rats and circulating Ang II in middle-aged and older rats. Moreover, by fasting, ACE2 protein expression was elevated in old rats. EOD fasting also significantly elevated the AT2 receptor protein and reduced the AT1aR/AT2R proteins ratio in the older rats (P < 0.001, P < 0.01, respectively).

CONCLUSION

Our findings suggest that fasting, particularly EOD, can attenuate age-related hypertension, partly through reset of the local renal RAS and increase of klotho protein expression.

The possible antioxidative effects of ketogenic diet by modifying brain klotho expression: a rat model study

Objectives: The ketogenic diet (KD) has long been used as an alternative nonpharmacological therapy to manage pharmacoresistant epilepsy. The anticonvulsant mechanisms of KD have yet to be fully elucidated. The present study explored whether a KD could exert antioxidative effects by altering brain Klotho (Kl) gene expression.Methods: Thirty male rats were divided into three groups: the normal diet (ND) group received standard rat chow; the calorie-restricted diet (CRD) group was maintained at 90% of the calculated energy need; and the KD group received a diet composed of 8% protein, 2% carbohydrates, and 90% fat (per calorie macronutrient). The levels of β-hydroxybutyrate (BHB) in the serum, Kl gene expression in the brain, and Kl protein, malondialdehyde (MDA), and protein carbonyl (PC) levels in the serum and brain were evaluated by standard methods.Results: The serum BHB levels in the KD group were significantly greater than those in the ND and CRD groups (p < 0.001). The Kl expression in the brain was significantly greater in the KD group than in the ND group (p = 0.028). The brain MDA levels in the KD group were significantly lower than those in the ND group (p = 0.006). Elevated BHB was positively correlated with brain Kl expression (r = 0.668, p < 0.001). The brain MDA levels were negatively correlated with brain Kl expression (r = -0.531, p = 0.003) and serum BHB levels (r = 0.472, p = 0.020).Discussion: KD might exert antioxidative effects by increasing BHB and upregulating Kl in the brain. This could be considered a possible anticonvulsant mechanism of KD.

Phosphorous intake in foods and phosphorus status markers in circulation in the Boston Puerto Rican Health Study

Phosphorus (P) additives may be deleterious for health. We measured the P content of key foods, and associations of P intake with biomarkers in the Boston Puerto Rican Health Study (BPRHS). Direct chemical analysis of 92 foods was done with the molybdenum blue spectrophotometric method and inductively coupled plasma mass spectrometry (ICP-MS). A novel algorithm was used to determine bioavailable, natural, and added P. We estimated P intakes from foods in 1323 participants, aged 45-75 y, and associations of these with serum P, fibroblast growth factor 23 (FGF23), parathyroid hormone (PTH), and Klotho. Relationships between intakes and status markers were assessed with Pearson's correlations and t-tests. Our food analyses generally support P values in the USDA nutrient database, with the exceptions of American and cheddar cheese, which had more P than in the database. Women had higher added P intake than men, and younger participants had higher added P than those older. Total P intake tended to be positively associated with serum P and klotho, and inversely associated with PTH, but relationships were not strong. Puerto Rican adults have high intake of additive P. Culturally sensitive interventions that highlight dietary quality are needed.

Podocyte senescence: from molecular mechanisms to therapeutics

As an important component of the glomerular filtration membrane, the state of the podocytes is closely related to kidney function, they are also key cells involved in aging and play a central role in the damage caused by renal aging. Therefore, understanding the aging process of podocytes will allow us to understand their susceptibility to injury and identify targeted protective mechanisms. In fact, the process of physiological aging itself can induce podocyte senescence. Pathological stresses, such as oxidative stress, mitochondrial damage, secretion of senescence-associated secretory phenotype, reduced autophagy, oncogene activation, altered transcription factors, DNA damage response, and other factors, play a crucial role in inducing premature senescence and accelerating aging. Senescence-associated-β-galactosidase (SA-β-gal) is a marker of aging, and β-hydroxybutyric acid treatment can reduce SA-β-gal activity to alleviate cellular senescence and damage. In addition, CCAAT/enhancer-binding protein-α, transforming growth factor-β signaling, glycogen synthase kinase-3β, cycle-dependent kinase, programmed cell death protein 1, and plasminogen activator inhibitor-1 are closely related to aging. The absence or elevation of these factors can affect aging through different mechanisms. Podocyte injury is not an independent process, and injured podocytes interact with the surrounding epithelial cells or other kidney cells to mediate the injury or loss of podocytes. In this review, we discuss the manifestations, molecular mechanisms, biomarkers, and therapeutic drugs for podocyte senescence. We included elamipretide, lithium, calorie restriction, rapamycin; and emerging treatment strategies, such as gene and immune therapies. More importantly, we summarize how podocyte interact with other kidney cells.

Systemic immunoinflammatory indexes in albuminuric adults are negatively associated with α-klotho: evidence from NHANES 2007-2016

BACKGROUND

Systemic Immune-Inflammation Index (SII) is a novel inflammatory biomarker closely associated with the inflammatory response and chronic kidney disease. Klotho is implicated as a pathogenic factor in the progression of kidney disease, and supplementation of Klotho may delay the progression of chronic kidney disease by inhibiting the inflammatory response. Our aim is to investigate the potential relationship between SII and Klotho in adult patients in the United States and explore the differences in the populations with and without albuminuria.

METHODS

We conducted a cross-sectional study recruiting adult participants with complete data on SII, Klotho, and urine albumin-to-creatinine ratio (ACR) from the National Health and Nutrition Examination Survey from 2007 to 2016. SII was calculated as platelet count × neutrophil count/lymphocyte count, with abnormal elevation defined as values exceeding 330 × 10^9/L. Albuminuria was defined as ACR >30 mg/g. Weighted multivariable regression analysis and subgroup analysis were employed to explore the independent relationship between SII and Klotho.

RESULTS

Our study included a total of 10,592 individuals. In all populations, non-albuminuria population, and proteinuria population with ACR ≥ 30, participants with abnormally elevated SII levels, as compared to those with SII less than 330 × 10^9/L, showed a negative correlation between elevated SII levels and increased Klotho, which persisted after adjusting for covariates.

CONCLUSIONS

There is a negative correlation between SII and Klotho in adult patients in the United States. This finding complements previous research but requires further analysis through large prospective studies.

Impact of 24-week supervised concurrent exercise on S-Klotho and vitamin D levels: A randomized controlled trial

This study aimed to investigate the effects 24 weeks of supervised exercise training at different intensities on S-Klotho and 25-hydroxyvitamin D plasma levels in young adults. This report was based on a secondary analysis from the ACTIBATE single-center unblinded randomized controlled trial (ClinicalTrials.gov ID: NCT02365129). A total of 144 young adults (~34% men and ~66% women) aged between 18 and 25 years took part in the study. The participants were randomly assigned to 3 different groups: (i) concurrent exercise training program based on the international physical activity recommendations at vigorous intensity (Ex-Vigorous group), (ii) at moderate intensity (Ex-Moderate group), and (iii) control group (no exercise). S-Klotho and 25-hydroxyvitamin D plasma levels were determined before and after the 24-week intervention programme. A significant decrease of 25-hydroxyvitamin D plasma levels were identified across time in all groups (p < 0.001), whereas no significant differences across time were observed in S-Klotho plasma levels (p = 0.497). There was no time x group interaction neither in S-Klotho nor in 25-hydroxyvitamin D plasma levels (all p > 0.7). In summary, our results showed that 24 weeks of supervised concurrent exercise training does not induce significant changes on S-Klotho and 25-hydroxyvitamin D independently of the exercise intensity in young adults.

The role of FGF15/FGF19 in the development of the central nervous system, eyes and inner ears in vertebrates

Fibroblast growth factor 19 (FGF19), and its rodent ortholog FGF15, is a member of a FGF subfamily directly involved in metabolism, acting in an endocrine way. During embryonic development, FGF15/FGF19 also functions as a paracrine or autocrine factor, regulating key events in a large number of organs. In this sense, the Fgf15/Fgf19 genes control the correct development of the brain, eye, inner ear, heart, pharyngeal pouches, tail bud and limbs, among other organs, as well as muscle growth in adulthood. These growth factors show relevant differences according to molecular structures, signalling pathway and function. Moreover, their expression patterns are highly dynamic at different stages of development, in particular in the central nervous system. The difficulty in understanding the action of these genes increases when comparing their expression patterns and regulatory mechanisms between different groups of vertebrates. The present review will address the expression patterns and functions of the Fgf15/Fgf19 genes at different stages of vertebrate embryonic development, with special attention to the regulation of the early specification, cell differentiation, and morphogenesis of the central nervous system and some sensory organs such as eye and inner ear. The most relevant anatomical aspects related to the structures analysed have also been considered in detail to provide an understandable context for the molecular and cellular studies shown.

Developmental regulation of endothelial-to-hematopoietic transition from induced pluripotent stem cells

Hematopoietic stem cells (HSCs) arise in embryogenesis from a specialized hemogenic endothelium (HE). In this process, HE cells undergo a unique fate change termed endothelial-to-hematopoietic transition, or EHT. While induced pluripotent stem cells (iPSCs) give rise to HE with robust hemogenic potential, the generation of bona fide HSCs from iPSCs remains a challenge. Here, we map single cell dynamics of EHT during embryoid body differentiation from iPSCs and integrate it with human embryo datasets to identify key transcriptional differences between in vitro and in vivo cell states. We further map ligand-receptor interactions associated with differential expression of developmental programs in the iPSC system. We found that the expression of endothelial genes was incompletely repressed during iPSC EHT. Elevated FGF signaling by FGF23, an endothelial pathway ligand, was associated with differential gene expression between in vitro and in vivo EHT. Chemical inhibition of FGF signaling during EHT increased HSPC generation in the zebrafish, while an FGF agonist had the opposite effect. Consistently, chemical inhibition of FGF signaling increased hematopoietic output from iPSCs. In summary, we map the dynamics of EHT from iPSCs at single cell resolution and identify ligand-receptor interactions that can be modulated to improve iPSC differentiation protocols. We show, as proof of principle, that chemical inhibition of FGF signaling during EHT improves hematopoietic output in zebrafish and the iPSC system.

The relationship between serum alpha-klotho levels and urinary incontinence in middle-aged and older females: insights from NHANES

Urinary incontinence (UI) in females is a prevailing condition that affects individuals across various age groups and is not limited to older females. The presence of serum alpha-Klotho (α-klotho) serves as a reliable biomarker to indicate the effects of antiaging. Nevertheless, the scientific research on the association between α-klotho and UI remains limited. Therefore, the purpose of this study is to investigate and evaluate the connection between α-klotho levels and the UI among females in the US. We utilized data from the National Health and Nutrition Examination Survey 2007-2016 to investigate the potential connection between α-klotho levels and the UI among females aged 40 to 79. Weighted linear regression models and sensitivity tests were conducted to explore the correlation. 2628 females were involved in this study, representing 22,492,348 non-institutionalized residents in the US. The mean age was 53.9 ± 0.2 years and the mean level of α-klotho was 873.0 ± 8.9 pg/mL. After adjusting for relevant covariables, weighted linear regression models revealed that individuals with severe UI exhibited significantly lower serum α-klotho levels (β =  - 100.66; 95% CI: - 156.31, - 45.01; P < 0.001) than those without UI. Furthermore, in stratified analyses, the correlation was not significant in individuals with normal weight, cardiovascular disease, or chronic kidney disease. We did not find a significant association between the type of UI and α-klotho levels. In the NHANES data from 2007 to 2016, a noteworthy inverse relationship was noted between α-klotho levels and the severity of UI among females aged 40 to 79.

Associations Between Urinary Phthalate Metabolites and Decreased Serum α-Klotho Level: A Cross-Sectional Study Among US Adults in Middle and Old Age

Phthalates are widely used chemicals with ubiquitous human exposure. Evidence indicated that phthalate exposure was associated with an increased risk of aging-related diseases. Klotho is a transmembrane protein with anti-aging functions, and its association with phthalates remains unknown. To find the association between phthalate exposure and serum α-Klotho, a cross-sectional study was performed in 4482 adults (40-79 years old) who completed the National Health and Nutrition Examination Survey (NHANES) (2007-2016). As shown in the results of multivariable linear regression analyses, mono(carboxynonyl) phthalate (MCNP) and mono-n-butyl phthalate (MBP) were inversely associated with α-Klotho, and the regression coefficients of MCNP and MBP were -1.14 (95% confidence interval (CI): -2.00, -0.27) and -0.08 (95% CI: -0.14, -0.02). Subgroup analyses based on the quartiles of each phthalate metabolite showed that both MCNP and MBP were only inversely associated with α-Klotho in the subgroups of the highest levels. For mono-isobutyl phthalate (MIBP), the inverse association with α-Klotho was only statistically significant in the subgroup of the lowest level, and the regression coefficient was -26.87 (95% CI: -52.53, -1.21). Our findings suggest that α-Klotho might be involved in the association of phthalate exposure with aging-related diseases. Future research investigating the causality between phthalates and α-Klotho and its underlying mechanisms is encouraged.

Systemic immune-inflammation mediates the association between Klotho protein and metabolic syndrome: findings from a large-scale population-based study

BACKGROUND

This study utilized large-scale population data from the National Health and Nutrition Examination Survey (NHANES) to elucidate the relationship between the Klotho protein and metabolic syndrome along with its components. We further investigated the possible mediating effect of inflammation on these relationships. Our objective was to identify biomarkers for risk stratification and potential therapeutic targets for metabolic syndrome.

METHODS

This study enrolled 13,119 participants aged 40-79 years, spanning five NHANES cycles from 2007 to 2016, with complete information on metabolic syndrome and the Klotho protein. The definition of metabolic syndrome followed the criteria of the National Cholesterol Education Program-Adult Treatment Panel III. Survey-weighted logistic regression and subgroup analysis were used to explore the associations between serum Klotho protein levels and metabolic syndrome, along with its components. Mediation analysis was performed to investigate the mediating effects of inflammation-related markers, including white blood cells, neutrophils, lymphocytes, monocytes, the neutrophil-to-lymphocyte ratio (NLR), the platelet-to-lymphocyte ratio (PLR), the systemic immune-inflammation index (SII) and the monocyte-to-HDL ratio (MHR), with the aim of elucidating how the Klotho protein influences the onset and progression of metabolic syndrome.

RESULTS

The study participants had an average age of 56.06 years (95% CI: 55.76-56.37), with a Klotho protein concentration of 798.10 pg/ml (95% CI: 656.50-980.50) and a 43.77% prevalence of metabolic syndrome (n = 5742). In the crude model, Klotho was negatively correlated with metabolic syndrome and its components, including central obesity, hypertension, and hypertriglyceridemia. After adjusting for all confounding factors, Klotho was demonstrated to be negatively associated only with metabolic syndrome (OR: 0.82, 95% CI: 0.70-0.97), hypertension (OR: 0.83, 95% CI: 0.70-0.98), and hypertriglyceridemia (OR: 0.78, 95% CI: 0.67-0.91). Subgroup and interaction analyses revealed significant interactions between age, sex, race/ethnicity, body mass index, and Klotho. Additionally, mediation analysis demonstrated that leukocytes, neutrophils and monocytes accounted for 34.78%, 31.91% and 7.13%, respectively, of the associations between Klotho and metabolic syndrome.

CONCLUSION

The serum concentration of Klotho protein was negatively associated with metabolic syndrome, with the relationship being partly mediated by systemic immune inflammation. The findings of this research revealed that the Klotho protein may be a valuable biomarker for risk stratification and a potential therapeutic target for metabolic syndrome.

Prostaglandin E2 signaling through prostaglandin E receptor subtype 2 and Nurr1 induces fibroblast growth factor 23 production

Bone cells produce fibroblast growth factor 23 (FGF23), a hormone regulating renal phosphate and vitamin D homeostasis, and a paracrine factor produced in further tissues. Chronic kidney disease and cardiovascular disorders are associated with early elevations of plasma FGF23 levels associated with clinical outcomes. FGF23 production is dependent on many conditions including inflammation. Prostaglandin E2 (PGE2) is a major eicosanoid with a broad role in pain, inflammation, and fever. Moreover, it regulates renal blood flow, renin secretion, natriuresis as well as bone formation through prostaglandin E receptor 2 (EP2). Here, we studied the role of PGE2 and its signaling for the production of FGF23. Osteoblast-like UMR-106 cells were exposed to EP receptor agonists, antagonists or RNAi. Wild type and EP2 knockout mice were treated with stable EP2 agonist misoprostol. Fgf23 or Nurr1 gene expression was determined by quantitative real-time PCR, hormone and further blood parameters by enzyme-linked immunosorbent assay and colorimetric methods. PGE2 and EP2 agonists misoprostol and butaprost enhanced FGF23 production in UMR-106 cells, effects mediated by EP2 and transcription factor Nurr1. A single dose of misoprostol up-regulated bone Fgf23 expression and FGF23 serum levels in wild type mice with subtle effects on parameters of mineral metabolism only. Compared to wild type mice, the FGF23 effect of misoprostol was significantly lower in EP2-deficient mice. To conclude, PGE2 signaling through EP2 and Nurr1 induces FGF23 production. Given the broad physiological and pathophysiological implications of PGE2 signaling, this effect is likely of clinical relevance.

The association between the triglyceride-glucose index and serum anti-aging protein α- Klotho: a population-based study

BACKGROUND

Both anti-aging protein α-Klotho and the triglyceride-glucose (TyG) index hold predictive value for the incidence, progression, and outcomes of cardiovascular disease, diabetes and many other diseases. However, their relationship remains unclear.

METHODS

We conducted a cross-sectional analysis using data from the National Health and Nutrition Examination Survey (NHANES) 2007-2016. Weighted multivariate linear regression models and subgroup analysis were constructed to assess the association between TyG index and α-Klotho levels. Nonlinear correlations were explored using restricted cubic splines (RCS), generalized additive models (GAM) and smooth curve fitting. Segmented regression model was conducted to explore potential threshold effects and identify the inflection point.

RESULTS

A total of 2568 participants satisfied the predetermined criteria were enrolled in the final analysis. After fully adjusting for covariates, TyG index was shown to be markedly negatively correlated with α-Klotho [β=-74.07, 95%CI (-100.29,-47.85), p < 0.001]. Gender was significantly correlated with this negative connection according to subgroup analysis and interaction testing (p for interaction < 0.05).Additionally, we discovered a linear association between TyG index and α-Klotho in all participants (p for nonlinear = 0.761), while non-linear association in female (p for nonlinear = 0.016).The analysis of threshold effect in the female participants found that the inflection point of TyG index was 8.01, exceed which the level of α-Klotho decreased significantly with increasing TyG index[β=-151.72, 95%CI (-201.93, -101.50), p < 0.001].

CONCLUSION

Our findings demonstrate a negative association between TyG index and α-Klotho levels, with the effect being more pronounced in females. TyG index may serve as an early indicator of individuals with low α-Klotho levels, especially among females. These findings highlight the need for gender-specific considerations in clinical interventions to improve public health. Further research is needed to clarify the causal direction of this association.

Inverted U-shaped relationship between serum vitamin B12 and α-Klotho levels in US adults: a cross-sectional study

Background

Serum vitamin B12 and α-Klotho are important markers associated with aging. Limited studies have been conducted on the relationship between vitamin B12 and α-Klotho.

Objectives

This study investigated the relationship between circulating α-Klotho and vitamin B12.

Methods

A total of 4,502 American adults with circulating vitamin B12 levels and α-Klotho levels from the National Health and Nutrition Examination Survey (2011-2014) were included. A weighted multiple linear regression model was used to evaluate the correlation between vitamin B12 and α-Klotho levels. To clarify potential non-linearities, smoothed curve fitting and threshold effects analysis were employed.

Results

A statistically significant non-linear relationship was found between vitamin B12 levels and circulating α-Klotho levels after adjusting for potential confounders. We observed an inverted U-shaped relationship between serum vitamin B12 levels and circulating α-Klotho levels. Notably, serum vitamin B12 levels below the threshold (1,020 pg/mL) exhibited a positive correlation with circulating α-Klotho levels (β = 0.14, 95% confidence interval (CI): 0.09-0.18, p < 0.0001). Conversely, serum vitamin B12 levels above the threshold (1,020 pg/mL) exhibited a negative correlation with circulating α-Klotho levels (β = -0.12,95% CI: -0.17--0.06, p < 0.0001). Sensitivity analyses were performed and consistent results were obtained.

Conclusion

This study demonstrated an inverted U-shaped relationship between circulating vitamin B12 and α-Klotho in American adults. The optimal concentration of serum vitamin B12 in American adults was found.

Association between serum Klotho and major depression: Results from the NHANES 2007-2016 and Mendelian randomization studies

BACKGROUND

Major depression is a public health problem facing the world. This study aimed to identify the risk factors for major depression and clarify their causal effects.

METHODS

Data from the National Health and Nutrition Examination Survey (NHANES). Multifactorial logistic regression analysis was used to calculate the effect of each variable on major depression. Subgroup analyses and interaction tests were conducted to observe the stability of the association between them. Nonlinear correlations were explored using restricted cubic spline plots. The causal effects of serum Klotho on major depression were assessed using Mendelian randomization (MR) analysis.

RESULTS

A total of 8359 participated in the study. After adjusting for all covariates, the risk of having major depression was 1.47 times higher for each unit rise in serum Klotho (OR = 1.47, 95 % CI = 1.07-2.02; P = 0.0183). MR analysis showed no causal relationship between serum Klotho levels and risk of major depression (OR = 1.09, 95 % CI = 0.91-1.30; P = 0.4120). Sensitivity analysis verified the reliability of the results.

CONCLUSIONS

Serum Klotho is positively associated with an increased risk of major depression in the U.S. population, but MR analyses did not show genetic causality between Klotho and major depression in individuals of European ancestry. Based on the results of the current study, no indication maintaining high levels of Klotho may increase the risk of major depression.

LIMITATIONS

The main limitation of this study is the inconsistency of the cross-sectional study and the MR population.

High Protein Diets and Glomerular Hyperfiltration in Athletes and Bodybuilders: Is Chronic Kidney Disease the Real Finish Line?

Several observational and experimental studies in humans have suggested that high protein intake (PI) causes intraglomerular hypertension leading to hyperfiltration. This phenomenon results in progressive loss of renal function with long-term exposure to high-protein diets (HPDs), even in healthy people. The recommended daily allowance for PI is 0.83 g/kg per day, which meets the protein requirement for approximately 98% of the population. A HPD is defined as a protein consumption > 1.5 g/kg per day. Athletes and bodybuilders are encouraged to follow HPDs to optimize muscle protein balance, increase lean body mass, and enhance performance. A series of studies in resistance-trained athletes looking at HPD has been published concluding that there are no harmful effects of HPD on renal health. However, the aim of these studies was to evaluate body composition changes and they were not designed to assess safety or kidney outcomes. Here we review the effects of HPD on kidney health in athletes and healthy individuals with normal kidney function.

Correlation of neutrophil-to-lymphocyte ratio and platelet-to-lymphocyte ratio with serum α-klotho levels in US middle-aged and older individuals: Results from NHANES 2007-2016

Background

The α-klotho (αKl) is widely accepted as an anti-aging and anti-inflammatory protein. However, it is rarely reported on the function and mechanism of αKl in the overall population (including healthy people and those with history of chronic disease). The neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) are established as predictors of systemic inflammation. This study aims to investigate the relationship between NLR, PLR, and αKl levels in the overall population.

Methods

Data from 10,124 adults aged 40 years old and above, collected from NHANES 2007-2016, were analyzed. Associations between NLR, PLR, and αKl levels were assessed by weighted multivariate linear regression analyses, adjusting for potential confounders. Subgroup analysis was conducted by gender, age, diabetes, cardiovascular disease, and chronic kidney disease.

Results

Weighted linear regression models showed that a significant negative correlation was observed between both NLR and PLR with αKl levels. Subgroup analysis revealed that the negative correlation between NLR and serum αKl levels was not significant in individuals aged 40-59 years and males, while this relationship remained stable across most other subgroups. The negative correlation between PLR and serum αKl levels was consistent across most subgroups but not significant in individuals with cardiovascular disease.

Conclusion

Our study revealed a significant negative relationship between inflammatory markers (NLR and PLR) and serum αKl levels, suggesting systemic inflammation may be linked to reduced αKl expression. Subgroup analyses showed that the relationship varies across different demographic and health-related factors. We provided insight into the significance of managing inflammation and preserving αKl levels.

Endocrine fibroblast growth factors in domestic animals

Fibroblast growth factors (FGFs) are a group of structurally homologous yet functionally pleiotropic proteins. Canonical and intracellular FGFs have primarily autocrine or paracrine effects. However, the FGF19 subfamily, composed of FGF15/19, FGF21, and FGF23, act as endocrine hormones that regulate bile acid, metabolic, and phosphorus homeostasis, respectively. Current research in human and rodent models demonstrates the potential of these endocrine FGFs to target various diseases, including disorders of inherited hypophosphatemia, chronic liver disease, obesity, and insulin resistance. Many diseases targeted for therapeutic use in humans have pathophysiological overlaps in domestic animals. Despite the potential clinical and economic impact, little is known about endocrine FGFs and their signaling pathways in major domestic animal species compared with humans and laboratory animals. This review aims to describe the physiology of these endocrine FGFs, discuss their current therapeutic use, and summarize the contemporary literature regarding endocrine FGFs in domestic animals, focusing on potential future directions.