New insights into the role of Klotho in inflammation and fibrosis: molecular and cellular mechanisms

Klotho protein: a multifaceted regulator in aging and cancer dynamics

Klotho, named after the youngest of the three Fates in Greek mythology daughters of Zeus and Nyx, who together spin the thread of life, allot destiny, and determine the time of passing for both mortals and immortals, is an important regulatory factor in aging and cancer dynamics. Initially described as an aging-suppressing protein, Klotho is now recognized for its more diverse role in modulating key signaling pathways like Wnt/β-catenin, IGF-1, PI3K/AKT, and TGF-β. Essentially, its various pro-cellular health functions, such as antioxidant, anti-inflammatory, and tumor-suppressive activities, are, in fact, considered that ensures the maintenance of cellular health and reduce complications related to aging. Klotho deficiency is associated with accelerated aging, chronic kidney disease, cardiovascular disorders, neurodegeneration, and various cancers. This review thus covers the twin roles of Klotho as an antiaging and tumor-suppressor protein, on their therapeutic potential, as well as advances in delivery systems and development of biomarkers and challenges for clinical translation.. Moreover, natural strategies like exercise and dietary interventions are explored that could help overcome Klotho deficiency. Further research with Klotho may offer a paradigm shift in the treatment of aging and cancer and add yet another avenue to increase survival of the patients.

Associations Between Inflammatory and Bone Turnover Markers and Mortality in Hemodialysis Patients

Background/Objectives: Chronic kidney disease-mineral and bone disorder (CKD-MBD) and systemic inflammation contribute to mortality in hemodialysis (HD) patients. The primary aim of this study was to determine whether specific CKD-MBD markers and inflammatory biomarkers are associated with increased mortality risk in HD patients. Methods: We conducted a retrospective cohort study on 63 stage 5D CKD patients undergoing maintenance HD. Serum intact parathyroid hormone (iPTH), soluble Klotho, calcium, phosphorus, 25(OH)D (25-hydroxyvitamin D), transforming growth factor-beta (TGF-β), vascular endothelial growth factor (VEGF), C-reactive protein (CRP), and interleukin-6 (IL-6) were analyzed. A Cox regression analysis assessed mortality predictors, and linear regression analysis evaluated CKD-MBD-inflammation correlations. Results: Lower iPTH (<329.3 pg/mL) levels were the only significant mortality predictor (p = 0.042). Other CKD-MBD markers (calcium, phosphorus, 25(OH)D, VEGF, TGF-β) did not impact survival. Soluble Klotho correlated positively with IL-6 (r = 0.57, p < 0.001), suggesting a compensatory inflammatory response. Conclusions: Our findings demonstrate that low iPTH levels and advanced age are independent predictors of mortality in hemodialysis patients. The positive association between soluble Klotho and IL-6 suggests a potential compensatory inflammatory response. These results highlight the need for further research to clarify underlying mechanisms and to explore novel therapeutic strategies.

In vitro and in-vivo exploration of physostigmine analogues to understand the mechanistic crosstalk between Klotho and targets for epilepsy

Background

Epilepsy and seizures are characterized by neuronal hyperexcitability and damage, influenced by metabolic dysregulation, neuroinflammation, and oxidative stress. Despite available treatments, many patients remain resistant to therapy, necessitating novel therapeutic strategies. Klotho, a neuroprotective, anti-inflammatory, and antioxidative protein has emerged as a potential modulator of epilepsy-related pathways.

Objective

This study investigates the therapeutic potential of novel physostigmine analogues in regulating Klotho expression and its downstream targets in epilepsy.

Methods

An integrative in vitro and in vivo approach was employed in PTZ-induced kindled mice. Behavioral assessments, including the Morris Water Maze (MWM), Rota Rod, Black and White Box, and Tail Suspension tests were conducted. Biochemical analyses quantified serum glucose, lipid profiles, pro-inflammatory cytokines (TNF-α, FOXO1), and apoptotic proteins (caspase-3). Quantitative real-time PCR (qRT-PCR) was performed to assess Klotho and epilepsy-associated gene expression (STAT3, Bax, Bcl2).

Results

The synthesized physostigmine analogues exhibited varying inhibitory effects on Klotho transcriptional activators, with Compound C (1,8-bis(phenylsulfonyl)-1,8-dihydropyrrolo [2,3-b] indole) showing the weakest inhibition (IC50 = 1.31 µM). In vivo, Compound C demonstrated anticonvulsant (p < 0.05), neuroprotective (5 mg/kg, p < 0.05, 10 mg/kg, p < 0.01, 20 mg/kg p < 0.0001), antidepressant (p < 0.05), and anti-inflammatory (p < 0.05) effects in PTZ-induced seizure models, improving motor function (p < 0.001), cognitive performance (p < 0.01), and reducing neuroinflammatory/metabolic markers (p < 0.05), while modulating STAT3 (p < 0.001), BAX (p < 0.001), Bcl2 (p < 0.05), and Klotho (p < 0.05) gene expression.

Conclusion

The therapeutic potential of 1,8-bis(phenylsulfonyl)-1,8-dihydropyrrolo [2,3-b] indole in epilepsy via Klotho modulation was observed. Targeting metabolic, inflammatory, and apoptotic pathways presents a promising strategy for epilepsy management. Further research is required to optimize clinical translation and ensure long-term efficacy and safety.

Macrophage Depletion Alleviates Immunosenescence in Diabetic Kidney by Modulating GDF-15 and Klotho

Cellular senescence is a hallmark of aging and contributes to age-related diseases, including diabetic nephropathy (DN). Additionally, macrophage-mediated inflammation has been linked with DKD. Therefore, we investigated the effect of macrophage depletion on kidney cell senescence in DN, focusing on the relationship between the GDF-15 and Klotho signaling pathways. Wistar albino rats (n = 24) were divided into four groups: healthy control, liposomal clodronate (LC)-treated healthy, diabetic, and LC-treated diabetic groups. Rats in the LC-treated healthy, diabetic, and LC-treated diabetic groups were intravenously administered LC once a week for 4 weeks. Rat models of type 2 diabetes were successfully established via the administration of streptozotocin and a high-fat diet, as evidenced by increased blood glucose levels, kidney weight to body weight (KW/BW) ratio, serum albumin, creatinine, and urea levels, kidney damage, and oxidative stress. However, LC-mediated macrophage depletion reduced the KW/BW ratio, improved serum and oxidative parameters, decreased inflammatory markers (IL-6 and TNF-α), and ameliorated oxidative stress. Additionally, LC treatment promoted macrophage polarization towards the anti-inflammatory phenotype, downregulated GDF-15 expression, upregulated Klotho expression, and ameliorated kidney damage. In conclusion, macrophage depletion combats kidney senescence by modulating Klotho and GDF-15, indicating their potential as novel targets in DN treatment.

Natural products in traditional Chinese medicine for renal fibrosis: a comprehensive review

Renal fibrosis represents the terminal pathological manifestation of most chronic kidney diseases, driving progressive loss of renal function. Natural products have emerged as promising therapeutic agents for preventing and ameliorating renal fibrosis due to their multi-target efficacy and favorable safety profiles. In this review, we conducted a comprehensive literature search on PubMed using the keywords "natural product" and "renal fibrosis" from 2004 to 2025, identifying 704 relevant articles. We systematically categorize and discuss the biological effects of key natural products and formulations with antifibrotic potential, focusing on five major classes: glycosides, flavonoids, phenolic compounds, anthraquinones, and terpenoids. Representative compounds from each category are highlighted for their mechanisms of action, including modulation of oxidative stress, inflammation, autophagy, and fibrosis signaling pathways. This review aims to provide a theoretical foundation for the development of natural product-based therapies to combat renal fibrosis, offering insights into their therapeutic potential and future research directions.

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 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.

Suyin Detoxification Prescription Regulates the Klotho and ERK/NF-κB Signaling Pathways to Alleviate Renal Injury

Chronic Kidney Disease (CKD) is an irreversible pathological condition resulting from the gradual accumulation of nephrotoxic substances. The application of the "Kidney Toxicity" theory in CKD treatment holds significant research potential and promising clinical prospects. We established a murine model of unilateral ureteral obstruction (UUO) and administered the traditional Chinese medicine prescription Suyin detoxification prescription (SDP). The efficacy of SDP was assessed by comparing the expression levels of Klotho, NF-κB, pNF-κB, VEGF, α-SMA, pERK1/2, and ERK1/2 proteins with those in the Sham operation group using immunohistochemistry, RT-qPCR, and Western Blot techniques. The study revealed a significant reduction in the expression of Klotho and VEGF proteins during the progression of renal fibrosis in mice, while there was a marked increase in the levels of pNF-κB, α-SMA, and pERK1/2 proteins, demonstrating statistical significance (p < 0.05). In UUO mice treated with a high dose of SDP, these proteins exhibited an opposite expression trend compared to that observed in pure operated model mice, with statistically significant differences (p < 0.05). Subsequently, we investigated the relationship between Klotho protein and the ERK/NF-κB signaling pathway-related proteins in human umbilical vein endothelial cells (HUVECs). Knockdown of Klotho protein in HUVECs confirmed its potential as a target for SDP's renal protective effects in vivo by regulating ERK/NF-κB signaling pathway-related proteins to some extent. The renoprotective effect of SDP is mediated through modulation of Klotho protein expression in renal tissues, thereby influencing the ERK/NF-κB signaling pathway and ameliorating the inflammatory processes associated with renal fibrosis. The present study has significantly contributed to the advancement and refinement of the pathogenesis of "Kidney Toxicity" as well as the therapeutic approach of "Kidney Detoxification".

A comparative genomic study across 396 liver biopsies provides deep insight into FGF21 mode of action as a therapeutic agent in metabolic dysfunction-associated steatotic liver disease

BACKGROUND

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a systemic disease with insulin resistance at its core. It affects one-third of the world population. Fibroblast growth factor (FGF21)-based therapies are effective in lowering hepatic fat content and fibrosis resolution; yet, its molecular functions remain uncertain. To gain insight into FGF21 mode of action (MoA), we investigated the transcriptomes of MASLD liver biopsies in relation to FGF21 expression.

METHODS

We compared N = 66 healthy controls with 396 MASLD patients and considered clinical characteristics relative to NAS disease activity scores (steatosis, lobular inflammation and ballooning), fibrosis grades and sex. We performed comparative genomics to identify FGF21-responsive DEGs, utilised information from FGF21-transgenic and FGF21-knockout mice and evaluated DEGs following FGF21 treatment of MASLD animal models. Eventually, we explored 188 validated FGF21 targets, and for ≥10 patients showing the same changes, we constructed MASLD-associated networks to determine the effects of FGF21 in reverting metabolic dysfunction.

RESULTS

We identified patients with increased 30% (N = 117), decreased 40% (N = 159) or unchanged 30% (N = 120) FGF21 expression, and the differences are caused by changes in FGF21 transcriptional control with ATF4 functioning as a key regulator. Based on comparative genomics, we discovered molecular circuitries of FGF21 in MASLD, notably FGF21-dependent induction of autophagy and oxidative phosphorylation/mitochondrial respiration. Conversely, FGF21 repressed hepatic glycogen-storage, its glucose release and gluconeogenesis, and therefore reduced glucose flux in conditions of insulin resistance. Furthermore, FGF21 repressed lipid transporters, and acetyl-CoA carboxylase-β to attenuate hepatic lipid overload and lipogenesis. Strikingly, FGF21 dampened immune response by repressing complement factors, MARCO, CD163, MRC1/CD206, CD4, CD45 and pro-inflammatory cytokine receptors. It also reverted procoagulant imbalance in MASLD, stimulated extracellular matrix degradation, repressed TGFβ- and integrin-signalling and lessened liver sinusoidal endothelial cell defenestration in support of fibrosis resolution.

CONCLUSIONS

We gained deep insight into FGF21-MoA in MASLD. However, heterogeneity in FGF21 expression calls for molecular stratifications as to identify patients which likely benefit from FGF21-based therapies.

KEY POINTS

Performed comprehensive genomics across liver biopsies of 396 MASLD patients and identified patients with increased, decreased and unchanged FGF21 expression. Used genomic data from FGF21 transgenic, knock-out and animal MASLD models treated with synthetic FGF21 analogues to identify FGF21-mode-of-action and metabolic networks in human MASLD. Given the significant heterogeneity in FGF21 expression, not all patients will benefit from FGF21-based therapies.

The role of serum α-Klotho levels in preventing hearing impairment among middle-aged and older adults: insights from a nationally representative sample

Background

The Klotho gene is implicated in suppressing aging phenotypes and influencing age-related diseases. Previous studies have delved into its connection with different diseases, yet the association between Klotho and hearing loss has rarely been examined. A recent population study explored the relationship between serum Klotho and hearing loss, but it had certain limitations. This study aims to analyze the link between serum α-Klotho levels and hearing thresholds, as well as the risk of hearing loss.

Methods

A total of 1,762 adults aged 40-69 years were selected from the 2011-2012 National Health and Nutrition Examination Survey (NHANES). Data on audiometry, serum α-Klotho levels, and relevant covariates were gathered. Statistical analyses, including linear and logistic regression, assessed the relationships of serum α-Klotho levels with hearing outcomes.

Results

Increased serum α-Klotho levels were correlated with diminished hearing thresholds and a lower risk of hearing loss. Quartile analysis revealed a significant trend, where elevated α-Klotho levels were linked to better auditory outcomes. Adjusted models controlled for various covariates, affirming the robustness of the findings. Non-linear associations were not observed.

Conclusion

This study provided novel evidence of a negative association between serum α-Klotho and hearing impairment in adults aged 40-69. Our results suggested a protective role of serum α-Klotho on adults with hearing loss.