Inhibition of EZH2 Reduces Aging-Related Decline in Interstitial Cells of Cajal of the Mouse Stomach.

BACKGROUND & AIMS: Restricted gastric motor functions contribute to aging-associated under-nutrition, sarcopenia, and frailty. We previously identified a decline in interstitial cells of Cajal (ICC, gastrointestinal pacemaker and neuromodulator cells) and their stem cells (ICC-SC) as a key factor of gastric aging. Altered functionality of the histone methyltransferase enhancer of zeste homolog 2 (EZH2) is central to organismal aging. Here, we investigated the role of EZH2 in the aging-related loss of ICC/ICC-SC. METHODS: klotho mice, a model of accelerated aging, were treated with the most clinically advanced EZH2 inhibitor, EPZ6438 (tazemetostat; 160 mg/kg i.p. BID for 3 weeks). Gastric ICC were analyzed by western blotting (WB) and immunohistochemistry. ICC and ICC-SC were quantified by flow cytometry. Gastric slow wave activity was assessed by intracellular electrophysiology. Ezh2 was deactivated in ICC by treating KitcreERT2/+;Ezh2fl/fl mice with tamoxifen. TRP53, a key mediator of aging-related ICC loss, was induced with nutlin 3a in gastric muscle organotypic cultures and an ICC-SC line. RESULTS: In klotho mice, EPZ6438 treatment mitigated the decline in the ICC growth factor KIT ligand/stem cell factor and gastric ICC. EPZ6438 also improved gastric slow wave activity and mitigated the reduced food intake and impaired body weight gain characteristic of this strain. Conditional genomic deletion of Ezh2 in Kit-expressing cells also prevented ICC loss. In organotypic cultures and ICC-SC, EZH2 inhibition prevented the aging-like effects of TRP53 stabilization on ICC/ICC-SC. CONCLUSIONS: Inhibition of EZH2 with EPZ6438 mitigates aging-related ICC/ICC-SC loss and gastric motor dysfunction, improving slow wave activity and food intake in klotho mice.

Association of elevated cerebrospinal fluid levels of the longevity protein α-Klotho with a delayed onset of cognitive impairment in Parkinson's disease patients.

BACKGROUND AND PURPOSE: Parkinson's disease (PD) is an age-related condition characterized by substantial phenotypic variability. Consequently, pathways and proteins involved in biological aging, such as the central aging pathway comprising insulin-like growth factor 1-α-Klotho-sirtuin 1-forkhead box O3-peroxisome proliferator-activated receptor γ, may potentially influence disease progression. METHODS: Cerebrospinal fluid (CSF) levels of α-Klotho in 471 PD patients were examined. Of the 471 patients, 96 carried a GBA1 variant (PD GBA1), whilst the 375 non-carriers were classified as PD wild-type (PD WT). Each patient was stratified into a CSF α-Klotho tertile group based on the individual level. Kaplan-Meier survival curves and Cox regression analysis stratified by tertile groups were conducted. These longitudinal data were available for 255 patients. Follow-up times reached from 8.4 to 12.4 years. The stratification into PD WT and PD GBA1 was undertaken to evaluate potential continuum patterns, particularly in relation to CSF levels. RESULTS: Higher CSF levels of α-Klotho were associated with a significant later onset of cognitive impairment. Elevated levels of α-Klotho in CSF were linked to higher Montreal Cognitive Assessment scores in male PD patients with GBA1 mutations. CONCLUSIONS: Our results indicate that higher CSF levels of α-Klotho are associated with a delayed cognitive decline in PD. Notably, this correlation is more prominently observed in PD patients with GBA1 mutations, potentially reflecting the accelerated biological aging profile characteristic of individuals harboring GBA1 variants.

Klotho enhances diastolic function in aged hearts through Sirt1-mediated pathways.

Aging leads to a progressive decline in cardiac function, increasing the risk of heart failure with preserved ejection fraction (HFpEF). This study elucidates the impact of α-Klotho, an anti-aging hormone, on cardiac diastolic dysfunction and explore its downstream mechanisms. Aged wild-type and heterozygous Klotho-deficient mice received daily injection of soluble α-Klotho (sKL) for 10 weeks, followed by a comprehensive assessment of heart function by echocardiography, intracardiac pressure catheter, exercise tolerance, and cardiac pathology. Our findings show that klotho deficiency accentuated cardiac hypertrophy, diastolic dysfunction, and exercise intolerance, while sKL treatment ameliorates these abnormalities and improves cardiac capillary densities. Downstream of klotho, we focused on the Sirtuin1 (Sirt1) signaling pathway to elucidate the potential underlying mechanism by which Klotho improves diastolic function. We found that decreased Klotho levels were linked with Sirt1 deficiency, whereas sKL treatment restored Sirt1 expression in aged hearts and mitigated the DNA damage response pathway activation. Through tandem mass tag proteomics and unbiased acetylomics analysis, we identified 220 significantly hyperacetylated lysine sites in critical cardiac proteins of aged hearts. We found that sKL supplementation attenuated age-dependent DNA damage and cardiac diastolic dysfunction. In contrast, Klotho deficiency significantly increased hyperacetylation of several crucial cardiac contractile proteins, potentially impairing ventricular relaxation and diastolic function, thus predisposing to HFpEF. These results suggest the potential benefit of sKL supplementation as a promising therapeutic strategy for combating HFpEF in aging.

U-shaped association between serum Klotho and all-cause mortality in US cardiovascular patients: a prospective cohort study.

Background: Increased levels of serum Klotho have been associated with a reduced risk of several cardiovascular diseases (CVD). However, limited studies exist on the association between serum Klotho and mortality in patients with CVD. Methods: We collected data from CVD patients in the National Health and Nutrition Examination Survey (NHANES) spanning 2007 to 2016. We linked NHANES data with the National Death Index to determine the survival status of participants. Univariate and multivariable Cox regression models were used to investigate the relationship between serum Klotho levels and mortality in CVD patients. The relationship between serum Klotho quartiles and mortality in CVD patients was visualized using Kaplan-Meier (KM) curves and restricted cubic spine. Finally, subgroup analyses were used to examine the association between serum Klotho and all-cause mortality in different populations. Results: 1905 patients with CVD were finally enrolled in our study with a mean follow-up of 7.1 years. The average age of the participants was 63.4 years, with 58.40% being male. KM showed that lower Klotho levels were associated with lower survival rates. After adjusting for potential confounders, patients with higher serum Klotho levels had lower all-cause mortality (Q1: 1.00, Q2: 0.58 (0.42-0.80), Q3: 0.69 (0.47-1.01), and Q4:0.64 (0.45-0.92). However, the relationship between serum Klotho levels and cardiovascular mortality was not statistically significant. Dose-response analysis shows a U-shaped relationship between serum Klotho levels and all-cause mortality in patients with CVD (P nonlinear=0.002). Subgroup analysis indicated that participants with a history of hypertension had a higher risk of all-cause mortality in serum Klotho Q4 compared to Q1 (P trend <0.05). Conclusion: The relationship between serum Klotho levels and all-cause mortality in CVD patients exhibits a U-shaped association. The underlying mechanisms of this association need further investigation.

BACH1 inhibits senescence, obesity, and short lifespan by ferroptotic FGF21 secretion.

Ferroptosis is a type of regulated cell death characterized by iron-dependent lipid peroxidation. A model cell system is constructed to induce ferroptosis by re-expressing the transcription factor BACH1, a potent ferroptosis inducer, in immortalized mouse embryonic fibroblasts (iMEFs). The transfer of the culture supernatant from ferroptotic iMEFs activates the proliferation of hepatoma cells and other fibroblasts and suppresses cellular senescence-like features. The BACH1-dependent secretion of the longevity factor FGF21 is increased in ferroptotic iMEFs. The anti-senescent effects of the culture supernatant from these iMEFs are abrogated by Fgf21 knockout. BACH1 activates the transcription of Fgf21 by promoting ferroptotic stress and increases FGF21 protein expression by suppressing its autophagic degradation through transcriptional Sqstm1 and Lamp2 repression. The BACH1-induced ferroptotic FGF21 secretion suppresses obesity in high-fat diet-fed mice and the short lifespan of progeria mice. The inhibition of these aging-related phenotypes can be physiologically significant regarding ferroptosis.

Associations between the TyG index and the ɑ-Klotho protein in middle-aged and older population relevant to diabetes mellitus in NHANES 2007-2016.

BACKGROUND: The anti-aging protein Klotho has diverse functions in antioxidative stress and energy metabolism through several pathways. While it has been reported that α-Klotho is downregulated in patients with insulin resistance (IR), the association between Klotho and IR is complex and controversial. The triglyceride-glucose (TyG) index has provided a practical method for assessing IR. With this in mind, our study aimed to investigate the relationship between the TyG index and soluble α-Klotho protein levels in US populations, both with and without diabetes mellitus. METHODS: This cross-sectional study analyzed data from middle-aged and older participants in the National Health and Nutrition Examination Survey (NHANES) conducted between 2007 and 2016. The participants were divided into two groups based on their diabetes mellitus status: those with diabetes and those without diabetes. To evaluate the relationship between the TyG index and the concentration of the α-Klotho protein in each group, a series of survey-weighted multivariable linear regression models were employed. Furthermore, to examine the association between these two variables, multivariable-adjusted restricted cubic spline curves and subgroup analysis were generated. RESULTS: The study involved 6,439 adults aged 40 years or older, with a mean age of 57.8 ± 10.9 years. Among them, 1577 (24.5%) had diabetes mellitus. A subgroup analysis indicated that the presence of diabetes significantly affected the relationship between the TyG index and the α-Klotho level. After considering all covariables, regression analysis of the participants without diabetes revealed that the α-Klotho concentration decreased by 32.35 pg/ml (95% CI: -50.07, -14.64) with each one unit increase in TyG (p < 0.001). The decline in α-Klotho levels with elevated TyG was more pronounced in the female population. In patients with diabetes mellitus, a non-linear association between the TyG index and α-Klotho was observed. There was no significant correlation observed between the two when TyG index were below 9.7. However, there was an increase in klotho levels of 106.44 pg/ml for each unit increase in TyG index above 9.7 (95% CI: 28.13, 184.74) (p = 0.008). CONCLUSION: Our findings suggested that the presence of diabetes may influence the relationship between the TyG index and soluble α-Klotho. Furthermore, there seem to be sex differences in individuals without diabetes. Further studies are necessary to validate these findings.

Attenuation of osteoarthritis progression via locoregional delivery of Klotho-expressing plasmid DNA and Tanshinon IIA through a stem cell-homing hydrogel.

BACKGROUND: Osteoarthritis (OA) is an aging-related degenerative joint disorder marked by joint discomfort and rigidity. Senescent chondrocytes release pro-inflammatory cytokines and extracellular matrix-degrading proteins, creating an inflammatory microenvironment that hinders chondrogenesis and accelerates matrix degradation. Targeting of senescent chondrocytes may be a promising approach for the treatment of OA. Herein, we describe the engineering of an injectable peptide-hydrogel conjugating a stem cell-homing peptide PFSSTKT for carrying plasmid DNA-laden nanoparticles and Tanshinon IIA (pPNP + TIIA@PFS) that was designed to attenuate OA progression by improving the senescent microenvironment and fostering cartilage regeneration. RESULTS: Specifically, pPNP + TIIA@PFS elevates the concentration of the anti-aging protein Klotho and blocks the transmission of senescence signals to adjacent healthy chondrocytes, significantly mitigating chondrocyte senescence and enhancing cartilage integrity. Additionally, pPNP + TIIA@PFS recruit bone mesenchymal stem cells and directs their subsequent differentiation into chondrocytes, achieving satisfactory chondrogenesis. In surgically induced OA model rats, the application of pPNP + TIIA@PFS results in reduced osteophyte formation and attenuation of articular cartilage degeneration. CONCLUSIONS: Overall, this study introduces a novel approach for the alleviation of OA progression, offering a foundation for potential clinical translation in OA therapy.

L-shaped association of systemic immune-inflammation index (SII) with serum soluble α-Klotho in the prospective cohort study from the NHANES database.

The systemic immune-inflammation index (SII), an integrated and ground-breaking inflammatory measure, has been widely used in various fields. We aimed to assess the association between the systemic immune-inflammation index (SII) and α-Klotho (a new anti-aging biomarker). In this cross-sectional investigation, people with complete information on SII and α-Klotho from the National Health and Nutrition Examination Survey (NHANES) between 2007 and 2016 were the study's subject population. SII was calculated by platelet count × neutrophil count/lymphocyte count. The association between SII and α-Klotho was investigated using multivariable linear regression and a generalized additive model. In order to explore the non-linear connection, we employed smoothed curve fitting. Subgroup analysis were also performed. A total of 13,701 participants with an average age of 57.73 ± 10.86 years were enrolled, of whom 51.53% were female. After fully adjustment, SII was negatively associated with serum soluble α-Klotho [ß(95% CI) = - 0.07 (- 0.08, - 0.05)]. Furthermore, we found L-shaped association between SII and klotho protein level, with the inflection point at 255 pg/ml. Subgroup analysis and interaction test revealed that there was no discernible dependence on gender, age, race, smoking, alcohol, diabetes and hypertension (all p for interaction > 0.05). SII level was negatively associated with serum klotho protein concentration in American adults. To verify our findings, more large-scale prospective investigations are still required.

High serum klotho levels are inversely associated with the risk of low muscle mass in middle-aged adults: results from a cross-sectional study.

Objective: Muscle mass gradually declines with advancing age, and as an anti-aging protein, klotho may be associated with muscle mass. This study aims to explore the relationship between klotho levels and muscle mass in the middle-aged population. Methods: Utilizing data from the National Health and Nutrition Examination Survey (NHANES) spanning 2011 to 2018, we conducted a cross-sectional analysis on a cohort of individuals aged 40-59. Weighted multivariable analysis was employed to assess the correlation between klotho and low muscle mass, with stratified and Restricted Cubic Spline (RCS) analyses. Results: The cross-sectional investigation revealed a significant negative correlation between klotho levels and the risk of low muscle mass (Model 3: OR = 0.807, 95% CI: 0.712-0.915). A notable interaction between klotho and sex was observed, with a significant interaction effect (P for interaction = 0.01). The risk association was notably higher in females. The risk association was notably higher in females. Additionally, RCS analysis unveiled a significant linear relationship between klotho and low muscle mass (P for nonlinear = 0.9495, P for overall<0.0001). Conclusion: Our observational analysis revealed a noteworthy inverse relationship between klotho and low muscle mass, particularly prominent among female participants. This discovery provides crucial insights for the development of more effective intervention strategies and offers a new direction for enhancing muscle quality in the middle-aged population.

Decreased Alpha Klotho Expression in Placentas Exposed to Severe Maternal Vascular Malperfusion.

BACKGROUND: Placental maternal vascular malperfusion (MVM) is characterized by accelerated villous maturation and has been associated with a decrease in the antiaging protein, alpha-klotho (AK). Our aim was to characterize AK protein and gene expression in the placenta and fetal organs. METHODS: We utilized 2 cohorts. First, we characterized AK protein expression in an autopsy cohort where cases were defined as MVM as the cause of fetal death compared to a stillborn control population. Second, we characterized placental and umbilical cord blood AK gene expression in a liveborn population with and without MVM. RESULTS: We found decreased protein expression in the villous trophoblastic cells of placentas exposed to severe MVM and decreased AK gene expression in placental tissue exposed to MVM. We did not see any statistically significant differences in fetal organ or umbilical cord blood AK expression based on the presence or absence of MVM. Furthermore, in liveborn infants, we also found increased odds of preterm birth with lower placental AK expression. CONCLUSIONS: Decreased AK gene and protein expression in the placenta in the setting of MVM is consistent with the theory of placental aging in MVM and is associated with increased odds of preterm birth.

The interaction between klotho protein and epigenetic alteration in diabetes and treatment options.

Introduction: Klotho is a membrane protein predominantly expressed in the kidneys, and its discovery was serendipitously made through gene-targeting experiments conducted on mice. Klotho has a favorable role in the regulation of multiple cellular processes, such as aging, oxidative stress, inflammation, and apoptosis. This regulation occurs through the targeting of diverse signaling molecules, cell membrane receptors, and ion channels, achieved by physical contacts or enzymatic activities of Klotho. This review examines the role of Klotho in the epigenetic regulation of molecules associated with diabetes. Methods: Authors conducted a thorough literature search using the PubMed®, Web of Science™, and Scopus®. Relevant articles up to September 2023, published in the English language were considered. We reviewed research databases searching for studies that included keywords klotho, epigenetic, and diabetes. Results: 14 related papers about epigenetic modification of proteins involved in diabetes pathogenesis were selected to be included in this narrative review. In the studies, the kidney was the most investigated organ regarding this correlation. Also, phosphorylation and methylation were the common epigenetic modifications of proteins by Klotho. Conclusion: Klotho has a significant role in the maturation of adipocytes and the regulation of systemic glucose metabolism, exhibiting a strong association with the pathogenesis of diabetes. Both epigenetic alterations and the modulation of protein phosphorylation by Klotho play significant roles in the regulation of Klotho expression and the modulation of other molecules implicated in the etiology of diabetes.

Elevated Serum Copper, Zinc, Selenium, and Lowered α-Klotho Associations: Findings from NHANES 2011-2016 Dataset.

The α-Klotho is crucial for human health and longevity. However, the relationship between trace elements and α-Klotho levels needs further investigation. We aimed to explore the relationship between serum levels of selenium (Se), copper (Cu), and zinc (Zn), and serum α-Klotho levels. We analyzed 2138 samples from the 2011-2016 National Health and Nutrition Examination Survey, and the weighted linear regression, WQS, and qgcomp models were utilized to evaluate the effects of these elements on serum α-Klotho levels, individually and combined. A negative correlation was observed between serum Cu concentration and serum α-Klotho levels (ß = - 0.128, 95% CI - 0.196, - 0.059), with each increase in Cu concentration grade showing a gradual decrease in serum α-Klotho levels (Ptrend = 0.002). The WQS model exhibited a negative correlation between the combined effect of Se, Cu, and Zn and serum α-Klotho levels (ß = - 0.035, 95%CI - 0.060, - 0.010), consistently in males (ß = - 0.038 (- 0.059, - 0.017)) and in the 40-49 age group (ß = - 0.059, 95% CI - 0.119, - 0.012). The qgcomp model mirrored these findings, showing a negative correlation in the combined effect index of Se, Cu, and Zn with serum α-Klotho levels (ß = - 0.027, 95% CI - 0.047, - 0.006), consistent in females (ß = - 0.032, 95% CI - 0.061, - 0.004) and in individuals with BMI ≥ 25 (ß = - 0.030, 95% CI - 0.054, - 0.006), and in the 40-49 age group (ß = - 0.047, 95% CI - 0.088, - 0.006). Elevated serum Cu levels may be associated with lower serum α-Klotho levels. The combined effect of serum Se, Cu, and Zn shows a negative correlation with serum α-Klotho levels, with Cu contributing the most. Our findings provide significant insights into assessing the role of trace nutrients in maintaining human health.

Klotho accelerates the progression of polycystic ovary syndrome through promoting granulosa cell apoptosis and inflammation.

The morbidity of polycystic ovary syndrome (PCOS) is in highly increasing rate nowadays. PCOS not only affects the fertility in women, but also threatens the health of whole life. Hence, to find the prognostic risk factors is of great value. However, the effective predictors in clinical practice of PCOS are still in blackness. In this study, we found Klotho was increased in FF (Follicular Fluid) and primary luteinized granulosa cells (GCs) from PCOS patients with hyperandrogenism. Furthermore, we found follicular Klotho was negatively correlated with numbers of mature oocytes, and positively correlated with serum testosterone, LH, and LH/FSH levels menstrual cycle and number of total antral follicles in PCOS patients. In primary luteinized GCs, the increased Klotho was accompanied with upregulation of cell apoptosis and inflammation-related genes. In ovaries of PCOS mice and cultured human KGN cell line, Klotho was up-regulated and accompanied by apoptosis, inflammation and mitochondrial dysfunction. Therefore, our findings suggest new mechanisms for granulosa cell injury and revealed to target inhibit Klotho maybe a new therapeutic strategy for treatment of PCOS.

The role of fibroblast growth factor 23 in regulation of phosphate balance.

Phosphate is essential for numerous biological processes, and serum levels are tightly regulated to accomplish these functions. The regulation of serum phosphate in a narrow physiological range is a well-orchestrated process and involves the gastrointestinal (GI) tract, bone, kidneys, and several hormones, namely, parathyroid hormone, fibroblast growth factor 23 (FGF23), and 1,25-dihydroxyvitamin D (1,25 Vitamin D). Although primarily synthesized in the bone, FGF23, an endocrine FGF, acts on the kidney to regulate phosphate and Vitamin D homeostasis by causing phosphaturia and reduced levels of 1,25 Vitamin D. Recent studies have highlighted the complex regulation of FGF23 including transcriptional and post-translational modification and kidney-bone cross talk. Understanding FGF23 biology has led to the identification of novel therapeutic agents to treat diseases that disrupt phosphate metabolism secondary to FGF23. The focus of this review is to provide an overview of phosphate homeostasis, FGF23 biology, and the role of FGF23 in phosphate balance.

Positive association of the anti-aging protein α-Klotho with insulin resistance and its inverse L-shaped relationship with glycaemic control in the middle-aged and elderly population.

PURPOSE: α-Klotho has been linked to insulin resistance (IR) in basic research. However, experimental evidence is inconsistent, and there is a lack of data from human research. This study seeks to elucidate the association of α-Klotho with IR in a nationwide, multiracial population. METHODS: A total of 5289 participants aged 40-79 years were included in the National Health and Nutrition Examination Survey (NHANES) spanning 2007-2016. Serum α-Klotho was measured using enzyme-linked immunosorbent assays (ELISA), and IR was evaluated by the homeostatic model assessment of insulin resistance (HOMA-IR). Weighted multivariate logistic and linear regression analysis, subgroup analysis stratified by demographic characteristics, medical condition or obesity status, and sensitivity analysis using propensity score matching (PSM) were performed. Restricted cubic splines (RCS) were performed to explore the nonlinear relationship. RESULTS: In the fully adjusted logistic regression model, a significant positive association was observed between log-transformed α-Klotho and IR (OR = 3.63, 95% CI: 1.56, 8.45), particularly in males or nonobese individuals (Pinteraction < 0.05). In the linear regression model, log10(α-Klotho) was associated with fasting blood glucose (FBG, ß = 1.25, 95% CI: 0.74, 1.76) and glycosylated hemoglobin (HbA1c, ß = 0.49, 95% CI: 0.20, 0.77). RCS revealed an inverse L-shaped dose-response relationship of α-Klotho with FBG and HbA1c (Pnonlinear <0.05). Beyond the inflection point of log10(α-Klotho) at 2.79, ß coefficients sharply rose for these glycaemic control indicators. CONCLUSION: The study provides clinical evidence supporting a positive association between α-Klotho and IR. Moreover, the inverse L-shaped relationship suggests that α-Klotho should reach a certain level to predict glycaemic changes effectively.

Enhanced Therapeutic Effects of Human Mesenchymal stem Cells Transduced with Secreted Klotho in a Murine Experimental Autoimmune Encephalomyelitis Model.

Treatment of multiple sclerosis (MS) remains a major challenge. The aim of this study was to evaluate the therapeutic potential of mesenchymal stem cells (MSCs) engineered with secreted Klotho (SKL) in an experimental autoimmune encephalomyelitis (EAE) mouse model of MS. EAE was induced in mice. MSCs or MSCs engineered with SKL (SKL-MSCs) were administered to EAE mice at the onset of disease. Hematoxylin-eosin and luxol fast blue staining were performed to evaluate histopathological changes. Expression of pro-inflammatory (TNF-α, IFN-γ, and IL-17) and anti-inflammatory (IL-10) cytokines was determined in the spinal cord using real-time PCR. Spinal cords were then processed for immunohistochemistry of the aforementioned cytokines. The frequencies of Th1, Th17, and regulatory T (Treg) cells were evaluated by flow cytometry of the spleen. The results showed that SKL-MSCs decreased clinical scores and reduced demyelination and inflammatory infiltration in the spinal cord more significantly than MSCs. Compared to MSCs, SKL-MSCs also exhibited a more profound capability of decreasing expression of TNF-α, IFN-γ, and IL-17 and increasing expression of IL-10 in the spinal cord with an enhanced homing to the inflamed tissue. Moreover, SKL-MSCs decreased the frequencies of Th1 and Th17 cells and increased the frequency of Treg cells in the spleen more potently than MSCs. Taken together, these findings demonstrate that SKL overexpression enhances the therapeutic potential of MSCs, as evidenced by significantly improved disease severity, decreased inflammation and tissue damage in the spinal cord, and a promoted shift in the Th17/Treg balance towards the anti-inflammatory Treg side in the EAE mice.

Recombinant Klotho protein protects pulmonary alveolar epithelial cells against sepsis-induced apoptosis by inhibiting the Bcl-2/Bax/caspase-3 pathway.

BACKGROUND: Inflammation-induced apoptosis of alveolar type II epithelial cells is a primary contributor to sepsis-induced acute respiratory distress syndrome (ARDS). Klotho is a single-pass transmembrane protein with anti-inflammatory and anti-apoptotic effects. However, the role and mechanism of Klotho in the development of ARDS remains unknown. OBJECTIVES: This study aimed to investigate the effect of Klotho on sepsis-induced apoptosis in human pulmonary alveolar epithelial cells (HPAEpiCs) together with the potential mechanism. MATERIAL AND METHODS: Cecal ligation and puncture (CLP) were performed to generate an in vivo sepsis model, and HPAEpiCs were treated with lipopolysaccharide (LPS) to mimic sepsis in vitro. Both models were administered recombinant Klotho protein. The morphology of the lung tissue was observed, and apoptotic cells and cell viability were detected. Interleukin (IL)-1ß, IL-6, and tumor necrosis factor alpha (TNF-α) levels were detected using enzyme-linked immunosorbent assay (ELISA), while the expression of Bcl-2, Bax and cleaved caspase-3 was detected with western blotting. RESULTS: Klotho reversed the CLP-induced decrease in mouse survival in vivo (p < 0.001) and increased inflammatory cell infiltration and inflammatory substance exudation in the lung tissue of mice with sepsis (both p < 0.001). Klotho also suppressed apoptosis (p < 0.001) as demonstrated by IL-1ß, IL-6 and TNF-α expression (all p < 0.001), and Bcl-2/Bax/caspase-3 pathway activation (p < 0.001). Klotho pretreatment significantly prevented LPS-induced apoptosis in vitro (p < 0.001), as demonstrated by IL-1ß, IL-6 and TNF-α upregulation (all p < 0.001); and Bcl-2/Bax/caspase-3 pathway activation in HPAEpiCs (p < 0.001). CONCLUSIONS: This study demonstrated that Klotho can ameliorate acute lung injury (ALI) induced by sepsis by inhibiting inflammatory responses and exerting anti-apoptotic effects by suppressing Bcl-2/Bax/caspase-3 pathway activation.

Skeletal Muscle Injury in Chronic Kidney Disease-From Histologic Changes to Molecular Mechanisms and to Novel Therapies.

Chronic kidney disease (CKD) is associated with significant reductions in lean body mass and in the mass of various tissues, including skeletal muscle, which causes fatigue and contributes to high mortality rates. In CKD, the cellular protein turnover is imbalanced, with protein degradation outweighing protein synthesis, leading to a loss of protein and cell mass, which impairs tissue function. As CKD itself, skeletal muscle wasting, or sarcopenia, can have various origins and causes, and both CKD and sarcopenia share common risk factors, such as diabetes, obesity, and age. While these pathologies together with reduced physical performance and malnutrition contribute to muscle loss, they cannot explain all features of CKD-associated sarcopenia. Metabolic acidosis, systemic inflammation, insulin resistance and the accumulation of uremic toxins have been identified as additional factors that occur in CKD and that can contribute to sarcopenia. Here, we discuss the elevation of systemic phosphate levels, also called hyperphosphatemia, and the imbalance in the endocrine regulators of phosphate metabolism as another CKD-associated pathology that can directly and indirectly harm skeletal muscle tissue. To identify causes, affected cell types, and the mechanisms of sarcopenia and thereby novel targets for therapeutic interventions, it is important to first characterize the precise pathologic changes on molecular, cellular, and histologic levels, and to do so in CKD patients as well as in animal models of CKD, which we describe here in detail. We also discuss the currently known pathomechanisms and therapeutic approaches of CKD-associated sarcopenia, as well as the effects of hyperphosphatemia and the novel drug targets it could provide to protect skeletal muscle in CKD.

Involvement of α-klotho in growth hormone (GH) signaling.

Growth hormone (GH) exerts multiple effects on different organs directly or via its main mediator, insulin-like growth factor1 (IGF1). In this study, we focused on the novel relationship between GH action and the antiaging hormone α-klotho. Immunofluorescent staining of α-klotho was observed in the renal distal tubules and pituitary glands of somatostatin- and GH-positive cells in wild-type (WT) mice. Treatment of 4-week-old WT mice with GH increased IGF1 mRNA expression in the pituitary gland, liver, heart, kidney, and bone but increased α-klotho mRNA expression only in the pituitary gland, kidney, and bone. Increased α-klotho protein levels were observed in the kidney but not in the pituitary gland. No induction of α-klotho RNA expression by GH was observed in juvenile mice with kidney disease, indicating GH resistance. Furthermore, GH and α-klotho supplementation in HEK293 cells transfected with GHR increased Janus kinase 2 mRNA (a GH downstream signal) expression compared to supplementation with GH alone. In conclusion, we suggest that 1) the kidney is the main source of secreted α-klotho, which is detected in blood by the downstream action of GH, 2) α-klotho induction by GH is resistant in kidney disease, and 3) α-klotho might be an enhanced regulator of GH signaling.

The association between testosterone and serum soluble klotho in the females: evidence from the NHANES database.

Objective: This research aimed to elucidate the relationship between testosterone levels and serum soluble klotho (S-klotho) concentrations in females aged 40-79 years using the National Health and Nutrition Examination Survey (NHANES) dataset. Design: Associations between testosterone and S-klotho were assessed through multivariable linear regression methodologies, spanning nonadjusted, minimally adjusted, and fully adjusted models. Settings: The investigation was conducted as a cross-sectional analysis utilizing the NHANES database. Participants: From 20,146 NHANES participants between 2013 and 2016, 2,444 females met the stipulated inclusion and exclusion criteria. Results: Free androgen index (FAI) showcased a negative correlation with S-klotho levels across all regression models (nonadjusted: ß -7.08, 95% CI -13.39- -0.76; minimally adjusted: ß -9.73, 95% CI -16.6- -2.84; fully adjusted: ß -7.63, 95% CI -14.75-0.51). Conversely, total testosterone did not exhibit significant associations with S-klotho across the models. In the nonadjusted model, estradiol was positively associated with S-klotho concentrations (ß 0.14, 95% CI 0.05-0.23), but this significance was not retained in subsequent regression models. Conclusion: Findings suggest that in U.S. females aged 40-79 years, FAI negatively correlates with S-klotho concentrations, while there is the lack of significant associations for total testosterone and estradiol.