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.

Molecular Interaction of Soluble Klotho with FGF23 in the Pathobiology of Aortic Valve Lesions Induced by Chronic Kidney Disease.

Chronic kidney disease (CKD) is linked to greater prevalence and rapid progression of calcific aortic valve disease (CAVD) characterized by valvular leaflet fibrosis and calcification. Fibroblast growth factor 23 (FGF23) level is elevated, and anti-aging protein Klotho is reduced in CKD patients. However, the roles of FGF23 and Klotho in the mechanism of aortic valve fibrosis and calcification remain unclear. We hypothesized that FGF23 mediates CKD-induced CAVD by enhancing aortic valve interstitial cell (AVIC) fibrosis and calcification, while soluble Klotho inhibits FGF23 effect. Methods and Results: In an old mouse model of CKD, kidney damages were accompanied by aortic valve thickening and calcification. FGF23 levels in plasma and aortic valve were increased, while Klotho levels were decreased. Recombinant FGF23 elevated the inflammatory, fibrogenic, and osteogenic activities in AVICs. Neutralizing antibody or shRNA targeting FGF23 suppressed the pathobiological activities in AVICs from valves affected by CAVD. FGF23 exerts its effects on AVICs via FGF receptor (FGFR)/Yes-associated protein (YAP) signaling, and inhibition of FGFR/YAP reduced FGF23's potency in AVICs. Recombinant Klotho downregulated the pathobiological activities in AVICs exposed to FGF23. Incubation of FGF23 with Klotho formed complexes and decreased FGF23's potency. Further, treatment of CKD mice with recombinant Klotho attenuated aortic valve lesions. Conclusion: This study demonstrates that CKD induces FGF23 accumulation, Klotho insufficiency and aortic valve lesions in old mice. FGF23 upregulates the inflammatory, fibrogenic and osteogenic activities in AVICs via the FGFR/YAP signaling pathway. Soluble Klotho suppresses FGF23 effect through molecular interaction and is capable of mitigating CKD-induced CAVD.

Human HPSE2 gene transfer ameliorates bladder pathophysiology in a mutant mouse model of urofacial syndrome.

Rare early-onset lower urinary tract disorders include defects of functional maturation of the bladder. Current treatments do not target the primary pathobiology of these diseases. Some have a monogenic basis, such as urofacial, or Ochoa, syndrome (UFS). Here, the bladder does not empty fully because of incomplete relaxation of its outflow tract, and subsequent urosepsis can cause kidney failure. UFS is associated with biallelic variants of HPSE2, encoding heparanase-2. This protein is detected in pelvic ganglia, autonomic relay stations that innervate the bladder and control voiding. Bladder outflow tracts of Hpse2 mutant mice display impaired neurogenic relaxation. We hypothesized that HPSE2 gene transfer soon after birth would ameliorate this defect and explored an adeno-associated viral (AAV) vector-based approach. AAV9/HPSE2, carrying human HPSE2 driven by CAG, was administered intravenously into neonatal mice. In the third postnatal week, transgene transduction and expression were sought, and ex vivo myography was undertaken to measure bladder function. In mice administered AAV9/HPSE2, the viral genome was detected in pelvic ganglia. Human HPSE2 was expressed and heparanase-2 became detectable in pelvic ganglia of treated mutant mice. On autopsy, wild-type mice had empty bladders, whereas bladders were uniformly distended in mutant mice, a defect ameliorated by AAV9/HPSE2 treatment. Therapeutically, AAV9/HPSE2 significantly ameliorated impaired neurogenic relaxation of Hpse2 mutant bladder outflow tracts. Impaired neurogenic contractility of mutant detrusor smooth muscle was also significantly improved. These results constitute first steps towards curing UFS, a clinically devastating genetic disease featuring a bladder autonomic neuropathy.

Association of Α-Klotho with regulation of Keap1/Nrf2/Interleukin-1 pathway and AMPA receptor trafficking in the brain of suicide victims.

Suicide is a significant public health challenge worldwide. Statistical data confirm a strong relationship between suicidal behavior and depressive disorders (DDs), but the molecular mechanisms of these diseases are still poorly understood. A growing body of research suggests that the Klotho-mediated pathway may be a novel intracellular target for the development of suicide-related disorders (including DDs). To verify this hypothesis, the link between α-Klotho levels, Nrf2-related inflammatory status (IL-1α, IL-1ß, Keap1, NFκB p65), AMPA (GluA1, GluA2, p-S831-GluA1, p-S845-GluA1) receptor subunit trafficking and AMPK (AMPKα1/2; pT172-AMPKα1) signalling pathways in the brain of suicide victims as compared to controls were investigated. Commercially available enzyme-linked immunoassay (ELISA) and Western blot analysis were performed in the hippocampus (HP) and frontal cortex (FCx) of suicide victims and matched controls. Group differences were assessed using an unpaired Student's t-test. A statistically significant decrease in the level of α-Klotho (HP: p=0.001; FCx: p=0.012) with an increase in IL-1ß (HP: p=0.0108) and IL-1α (FCx: p=0.009) concentrations were shown. These alterations were associated with increased Keap1 (FCx: p=0.023) and NF-κB-p65 (HP: p=0.039; FCx: p=0.013 nuclear fraction) protein levels. Furthermore, a significant reduction in p-S831-GluA1 (HP: p=0.029; FCx=0.002) and p-S845-GluA1 (HP: p=0.0012) proteins was observed. Similarly, the level of GluA2 (HP: p=0.011; FCx: p=0.002) and in p-T172-AMPKα1 (HP: p=0.0288; FCx: p=0.0338) protein were statistically decreased. Our findings demonstrate that a reduction in α-Klotho levels in brain structures related to mood disorders (HP, FCx) correlates with suicidal behavior. Moreover, our study provides novel insights into the molecular mechanisms underlying suicide-related disorders, highlighting the role of α-Klotho, Nrf2-related inflammatory status, AMPA receptor trafficking, and AMPK signaling pathways in the pathophysiology of suicidal behavior. These results may have implications for the development of targeted interventions for individuals at risk of suicide.

Deciphering molecular mechanisms underlying the inhibition of ß-glucuronidase by xanthones from Centaurium spicatum.

Herein, we scrutinized the inhibitory potential of five xanthones and a flavonoid, sourced from Centaurium spicatum, against ß-glucuronidase activity. The results showed that gentisin and azaleatin emerged as the most potent inhibitors, with significantly lower IC50 values of 0.96 ± 0.10 and 0.57 ± 0.04 µM, respectively. The evaluation of enzyme kinetics unveiled that the isolated xanthones manifested inhibition of ß-glucuronidase through a mixed inhibition mode, whereas azaleatin exhibited a noncompetitive inhibition mechanism. The findings from molecular docking analysis unveiled that the compounds under investigation, particularly azaleatin, displayed comparatively diminished binding affinities towards ß-glucuronidase. Furthermore, the tested drugs were shown to occupy a common binding site as the employed reference drug. Our comprehensive Molecular Dynamics (MD) simulations analysis revealed consistent trajectories for the investigated drugs, wherein azaleatin and gentisin demonstrated notable stabilization of energy levels. Analysis of various MD parameters revealed that drugs with the lowest IC50 values maintained relatively stable interactions with ß-glucuronidase. These drugs were shown to exert notable alterations in their conformation or flexibility upon complexation with the target enzyme. Conversely, the flexibility and accessibility of ß-glucuronidase was reduced upon drug binding, particularly with azaleatin and gentisin, underscoring the stability of the drug-enzyme complexes. Analysis of Coul-SR and LJ-SR interaction energies unveiled consistent and stable interactions between certain isolated drugs and ß-glucuronidase. Azaleatin notably displayed the lowest average Coul-SR interaction energy, suggesting strong electrostatic interactions with the enzyme's active site and significant conformational variability during simulation. Remarkably, LJ-SR interaction energies across different xanthones complexes were more negative than their Coul-SR counterparts, emphasizing the predominant role of van der Waals interactions, encompassing attractive dispersion and repulsive forces, in stabilizing the drug-enzyme complexes rather than electrostatic interactions.

Molecular cloning and characterisation of root-specific SlREO promoter of the Indian tomato (Solanum lycopersicum L.) cultivar.

Genetic transformation is helpful in enhancing crops, utilising promoters that can be constitutive, inducible, or tissue-specific. However, the use of constitutive promoters may hinder plant growth due to energy consumption during cellular processes. To optimise transgene effects, tissue-specific promoters like root-specific ones prove valuable in addressing root-related issues and enhancing productivity. Yet, identified root-specific promoters in crop are limited. To address this gap, the expression pattern of the root-specific SlREO promoter was examined across various crops. Sequencing confirmed its identity and high homology (99%) with the NCBI database, distinct from other plants tested. Using the PLACE database, six motifs associated with root expression were identified, along with several other important elements. The 2.4kb SlREO promoter was linked to a ß-glucuronidase (GUS) reporter gene alongside the CaMV35S promoter in pRI 201-AN-GUS vectors to study its expression. Histochemistry revealed strong root-specific expression in tomato (Solanum lycopersicum ) root tissues and limited expression in stems. However, the SlREO promoter did not consistently maintain its root-specific expression in other plants. Conversely, the CaMV35S promoter exhibited constitutive expression across all tissues in various plants. This study underscores the potential of the SlREO promoter as a root-specific regulatory element, offering avenues for improving crops, particularly against environmental stresses.

Gut microbial ß-Glucuronidase: A key regulator of endobiotic homeostasis.

Previous studies have explored the role of the gut microbiota in regulating endobiotic homeostasis, but the precise mechanisms remain unclear. In this issue of Cell Host & Microbe, Simpson et al. identified two predominant subtypes of gut microbial ß-Glucuronidase (gmGUS) that can reactivate hormones and neurotransmitters to regulate endobiotic homeostasis.

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.

Knockout of the longevity gene Klotho perturbs aging and Alzheimer's disease-linked brain microRNAs and tRNA fragments.

Overexpression of the longevity gene Klotho prolongs lifespan, while its knockout shortens lifespan and impairs cognition via perturbation of myelination and synapse formation. However, comprehensive analysis of Klotho knockout effects on mammalian brain transcriptomics is lacking. Here, we report that Klotho knockout alters the levels of aging- and cognition related mRNAs, long non-coding RNAs, microRNAs and tRNA fragments. These include altered neuronal and glial regulators in murine models of aging and Alzheimer's disease and in human Alzheimer's disease post-mortem brains. We further demonstrate interaction of the knockout-elevated tRNA fragments with the spliceosome, possibly affecting RNA processing. Last, we present cell type-specific short RNA-seq datasets from FACS-sorted neurons and microglia of live human brain tissue demonstrating in-depth cell-type association of Klotho knockout-perturbed microRNAs. Together, our findings reveal multiple RNA transcripts in both neurons and glia from murine and human brain that are perturbed in Klotho deficiency and are aging- and neurodegeneration-related.

Hypoxia-induced activation of HIF-1alpha/IL-1beta axis in microglia promotes glioma progression via NF-κB-mediated upregulation of heparanase expression.

BACKGROUND: Glioma is a common tumor that occurs in the brain and spinal cord. Hypoxia is a crucial feature of the tumor microenvironment. Tumor-associated macrophages/microglia play a crucial role in the advancement of glioma. This study aims to illuminate the detailed mechanisms by which hypoxia regulates microglia and, consequently, influences the progression of glioma. METHODS: The glioma cell viability and proliferation were analyzed by cell counting kit-8 assay and 5-ethynyl-2'-deoxyuridine assay. Wound healing assay and transwell assay were implemented to detect glioma cell migration and invasion, respectively. Enzyme-linked immunosorbent assay was conducted to detect protein levels in cell culture medium. The protein levels in glioma cells and tumor tissues were evaluated using western blot analysis. The histological morphology of tumor tissue was determined by hematoxylin-eosin staining. The protein expression in tumor tissues was determined using immunohistochemistry. Human glioma xenograft in nude mice was employed to test the influence of hypoxic microglia-derived interleukin-1beta (IL-1ß) and heparanase (HPSE) on glioma growth in vivo. RESULTS: Hypoxic HMC3 cells promoted proliferation, migration, and invasion abilities of U251 and U87 cells by secreting IL-1ß, which was upregulated by hypoxia-induced activation of hypoxia inducible factor-1alpha (HIF-1α). Besides, IL-1ß from HMC3 cells promoted glioma progression and caused activation of nuclear factor-κB (NF-κB) and upregulation of HPSE in vivo. We also confirmed that IL-1ß facilitated HPSE expression in U251 and U87 cells by activating NF-κB. Hypoxic HMC3 cells-secreted IL-1ß facilitated the proliferation, migration, and invasion of U251 and U87 cells via NF-κB-mediated upregulation of HPSE expression. Finally, we revealed that silencing HPSE curbed the proliferation and metastasis of glioma in mice. CONCLUSION: Hypoxia-induced activation of HIF-1α/IL-1ß axis in microglia promoted glioma progression via NF-κB-mediated upregulation of HPSE expression.

Glycooligomer-Functionalized Catalytic Nanocompartments Co-Loaded with Enzymes Support Parallel Reactions and Promote Cell Internalization.

A major shortcoming associated with the application of enzymes in drug synergism originates from the lack of site-specific, multifunctional nanomedicine. This study introduces catalytic nanocompartments (CNCs) made of a mixture of PDMS-b-PMOXA diblock copolymers, decorated with glycooligomer tethers comprising eight mannose-containing repeating units and coencapsulating two enzymes, providing multifunctionality by their in situ parallel reactions. Beta-glucuronidase (GUS) serves for local reactivation of the drug hymecromone, while glucose oxidase (GOx) induces cell starvation through glucose depletion and generation of the cytotoxic H2O2. The insertion of the pore-forming peptide, melittin, facilitates diffusion of substrates and products through the membranes. Increased cell-specific internalization of the CNCs results in a substantial decrease in HepG2 cell viability after 24 h, attributed to simultaneous production of hymecromone and H2O2. Such parallel enzymatic reactions taking place in nanocompartments pave the way to achieve efficient combinatorial cancer therapy by enabling localized drug production along with reactive oxygen species (ROS) elevation.

The Uptake of Heparanase into Mast Cells Is Regulated by Its Enzymatic Activity to Degrade Heparan Sulfate.

Mast cells take up extracellular latent heparanase and store it in secretory granules. The present study examined whether the enzymatic activity of heparanase regulates its uptake efficiency. Recombinant mouse heparanase mimicking both the latent and mature forms (L-Hpse and M-Hpse, respectively) was internalized into mastocytoma MST cells, peritoneal cell-derived mast cells, and bone marrow-derived mast cells. The internalized amount of L-Hpse was significantly higher than that of M-Hpse. In MST cells, L-Hpse was continuously internalized for up to 8 h, while the uptake of M-Hpse was saturated after 2 h of incubation. L-Hpse and M-Hpse are similarly bound to the MST cell surface. The expression level of cell surface heparan sulfate was reduced in MST cells incubated with M-Hpse. The internalized amount of M-Hpse into mast cells was significantly increased in the presence of heparastatin (SF4), a small molecule heparanase inhibitor that does not affect the binding of heparanase to immobilized heparin. Enzymatically quiescent M-Hpse was prepared with a point mutation at Glu335. The internalized amount of mutated M-Hpse was significantly higher than that of wild-type M-Hpse but similar to that of wild-type and mutated L-Hpse. These results suggest that the enzymatic activity of heparanase negatively regulates the mast cell-mediated uptake of heparanase, possibly via the downregulation of cell surface heparan sulfate expression.

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.

Gut microbiota biotransformation of drug glucuronides leading to gastrointestinal toxicity: Therapeutic potential of bacterial ß-glucuronidase inhibition in mycophenolate-induced enteropathy.

AIMS: Drug-induced enteropathy is often associated with the therapeutic use of certain glucuronidated drugs. One such drug is mycophenolic acid (MPA), a well-established immunosuppressant of which gastrointestinal adverse effects are a major concern. The role of bacterial ß-glucuronidase (ß-G) from the gut microbiota in MPA-induced enteropathy has recently been discovered. Bacterial ß-G hydrolyzes MPAG, the glucuronide metabolite of MPA excreted in the bile, leading to the digestive accumulation of MPA that would favor in turn these adverse events. We therefore hypothesized that taming bacterial ß-G activity might reduce MPA digestive exposure and prevent its toxicity. MAIN METHODS: By using a multiscale approach, we evaluated the effect of increasing concentrations of MPA on intestinal epithelial cells (Caco-2 cell line) viability, proliferation, and migration. Then, we investigated the inhibitory properties of amoxapine, a previously described bacterial ß-G inhibitor, by using molecular dynamics simulations, and evaluated its efficiency in blocking MPAG hydrolysis in an Escherichia coli-based ß-G activity assay. The pharmacological effect of amoxapine was evaluated in a mouse model. KEY FINDINGS: We observed that MPA impairs intestinal epithelial cell homeostasis. Amoxapine efficiently blocks the hydrolysis of MPAG to MPA and significantly reduces digestive exposure to MPA in mice. As a result, administration of amoxapine in MPA-treated mice significantly attenuated gastrointestinal lesions. SIGNIFICANCE: Collectively, these results suggest that the digestive accumulation of MPA is involved in the pathophysiology of MPA-gastrointestinal adverse effects. This study provides a proof-of-concept of the therapeutic potential of bacterial ß-G inhibitors in glucuronidated drug-induced enteropathy.

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.

Serum klotho associated with thyroid hormone in adults: A population-based cross-sectional research.

BACKGROUND AND STUDY AIM: The klotho protein, a multifunctional protein, has been shown to be associated with a wide range of endocrine diseases and has been linked to thyroid tumourigenesis. However, the relationship between serum klotho levels and thyroid hormones remains poorly understood. This study aimed to explore the correlation between serum klotho levels and thyroid hormones. METHODS: Data was obtained from the NHANES cycles 2007-2008, 2009-2010, and 2011-2012. A total of 4674 participants were recruited for this study. Statistical analysis was using multiple linear regression analyses, and restricted cubic spline plots (RCS) to investigate the association between serum klotho levels and serum levels of thyroid hormones. RESULTS: In the unadjusted covariate model, ln(klotho) significantly positively correlated with tT3, tT4, fT3, tT4/fT4, and tT3/fT3 (all P<0.01) and negatively correlated with TSH, tT4/tT3, and fT4/fT3 (all P<0.05). Furthermore, tT3, tT4, fT3and tT3/fT3 (P < 0.05) were still significant in the adjusted model. And it is worth noting that there is an approximately L-shaped nonlinear relationship between ln(klotho) and fT3,tT3 with a cut-off point of 6.697 (P-non-linear < 0.05). The stratification analysis showed gender and iodine level differences in the relationship between serum Klotho levels and thyroid hormones. CONCLUSION: There is an L-shaped nonlinear relationship between ln(klotho) and fT3, tT3, suggesting that klotho could be involved in the physiological regulation of thyroid function.

Association Between the Serum α-Klotho Level and Insulin Resistance in Adults: NHANES 2007-2016.

OBJECTIVE: This study aimed to investigate the relationship between serum α-Klotho levels and insulin resistance (IR), a precursor to type 2 diabetes. METHODS: The study analyzed data from 4,758 adult participants in the National Health and Nutrition Examination Survey (NHANES) spanning from 2007 to 2016. The relationship between α-Klotho concentration and IR was assessed using the Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) and odds ratios (OR) derived from logistic regression models. RESULTS: Results showed that every 1-ln increase in α-Klotho concentration raised the HOMA-IR value by 0.55 (95% confidence interval 0.35-0.74) and the odds of IR by 64% (odds ratio 1.64; 95% confidence interval 1.28-2.1). The odds of IR was 40% greater in highest tertile than in the lowest tertile. CONCLUSION: The findings of this study underscore a significant correlation between increased serum α-Klotho levels and the prevalence of IR.

ADAM10 as a major activator of reactive oxygen species production and klotho shedding in podocytes under diabetic conditions.

Early stages of diabetes are characterized by elevations of insulin and glucose concentrations. Both factors stimulate reactive oxygen species (ROS) production, leading to impairments in podocyte function and disruption of the glomerular filtration barrier. Podocytes were recently shown to be an important source of αKlotho (αKL) expression. Low blood Klotho concentrations are also associated with an increase in albuminuria, especially in patients with diabetes. We investigated whether ADAM10, which is known to cleave αKL, is activated in glomeruli and podocytes under diabetic conditions and the potential mechanisms by which ADAM10 mediates ROS production and disturbances of the glomerular filtration barrier. In cultured human podocytes, high glucose increased ADAM10 expression, shedding, and activity, NADPH oxidase activity, ROS production, and albumin permeability. These effects of glucose were inhibited when cells were pretreated with an ADAM10 inhibitor or transfected with short-hairpin ADAM10 (shADAM10) or after the addition soluble Klotho. We also observed increases in ADAM10 activity, NOX4 expression, NADPH oxidase activity, and ROS production in αKL-depleted podocytes. This was accompanied by an increase in albumin permeability in shKL-expressing podocytes. The protein expression and activity of ADAM10 also increased in isolated glomeruli and urine samples from diabetic rats. Altogether, these results reveal a new mechanism by which hyperglycemia in diabetes increases albumin permeability through ADAM10 activation and an increase in oxidative stress via NOX4 enzyme activation. Moreover, αKlotho downregulates ADAM10 activity and supports redox balance, consequently protecting the slit diaphragm of podocyteσ under hyperglycemic conditions.

Triiodothyronine enhances various forms of kidney-specific Klotho protein and suppresses the Wnt/ß-catenin pathway: Insights from in-vitro, in-vivo and in-silico investigations.

Age-related diseases are intricately linked to the molecular processes underlying aging, with the decline of the antiaging protein Klotho being a key factor. Investigating these processes is crucial for developing therapeutic strategies. The age-associated reduction in Klotho expression, coupled with a decline in the endocrine hormone triiodothyronine (T3), prompted a detailed exploration of their potential interplay. Our research, conducted through both in-vitro and in-vivo studies on BALB/c mice, unveiled a significant capacity of T3 to upregulate various forms of Klotho via ATF-3/p-c-Jun transcription factor. This effect was particularly noteworthy in aged individuals, where Klotho expression had waned compared to their younger counterparts. Importantly, T3 demonstrated a promising therapeutic impact in rejuvenating Klotho expression in this context. Further investigations elucidated the molecular mechanisms underlying T3's impact on aging-related pathways. In-vitro and in-vivo experiments established T3's ability to downregulate the Wnt/ß-Catenin pathway by enhancing Klotho expression. In-silico analyses provided insights into Klotho's intricate role, showing its capacity to inhibit Wnt ligands such as Wnt3 and Wnt8a, consequently disrupting their interaction with the Wnt receptor. Additionally, T3 was found to downregulate kidney-specific GSK-3ß expression through the augmentation of Klotho expression. The study also highlighted T3's role in maintaining calcium and phosphate homeostasis via Klotho. This comprehensive investigation not only sheds light on the intricate mechanisms governing aging processes but also presents promising avenues for therapeutic interventions targeting the Wnt/ß-Catenin pathway implicated in various age-associated diseases.