Klotho upregulation contributes to the neuroprotection of ligustilide in an Alzheimer's disease mouse model

Lessons from Klotho mouse models to understand mineral homeostasis

AIM

Klotho, a key component of the endocrine fibroblast growth factor receptor-fibroblast growth factor axis, is a multi-functional protein that impacts renal electrolyte handling. The physiological significance of Klotho will be highlighted in the regulation of calcium, phosphate, and potassium metabolism.

METHODS

In this review, we compare several murine models with different renal targeted deletions of Klotho and the insights into the molecular and physiological function that these models offer.

RESULTS

In vivo, Klotho deficiency is associated with severely impaired mineral metabolism, with consequences on growth, longevity and disease development. Additionally, we explore the perspectives of Klotho in renal pathology and vascular events, as well as potential Klotho treatment options.

CONCLUSION

This comprehensive review emphasizes the use of Klotho to shed light on deciphering the renal molecular in vivo mechanisms in electrolyte handling, as well as novel therapeutic interventions.

Comparing Western and traditional Chinese medicine for male sexual dysfunction: can Klotho represent a silk road?

Traditional Chinese medicine (TCM) and Western Medicine both have shown efficacy in treating male sexual dysfunction (MSD). The aim of this perspective paper is to discuss a possible link between Western medicine and TCM in the MSD field as represented by the entity of Klotho. Klotho is a recently discovered protein, mainly expressed in the kidney, encoded by the anti-aging gene klotho. Not only is Klotho significantly correlated with the development and progression of kidney diseases and their complications, but increasing evidence indicates that it is also closely related to MSD. A comprehensive search within PubMed database was performed to retrieve available evidence on Klotho's roles, particularly in kidney and in MSD. Indeed, in the TCM theory, the concept of the "kidney" is entirely different from the Western medicine: it is closely related to metabolism and to the reproductive, nervous, endocrine systems, being more than just a urinary organ. According to the "Kidney storing essence (jīng) and governing reproduction" (KSEGR) theory, a cornerstone in TCM, the treatment of MSD mainly consists of restoring the kidney's function. Signs of decreasing kidney essence show a consistent similarity to deficiencies of Klotho, also for what regards the male sexual function. Based on the current evidence, Klotho may represent a potential biological indicator for sexual desire and sexual function and a kind of new scientific Silk Road between TCM and Western medicine for MSD; nevertheless, there is a need to conduct further high-quality research to prove this hypothesis.

Klotho: molecular mechanisms and emerging therapeutics in central nervous system diseases

Klotho is recognized as an aging-suppressor protein that is implicated in a variety of processes and signaling pathways. The anti-inflammatory, anti-apoptotic, anti-oxidant, and anti-tumor bioactivities of klotho have extended its application in neurosciences and made the protein popular for its lifespan-extending capacity. Furthermore, it has been demonstrated that klotho levels would reduce with aging and numerous pathologies, particularly those related to the central nervous system (CNS). Evidence supports the idea that klotho can be a key therapeutic target in CNS diseases such as amyotrophic lateral sclerosis, Parkinson's disease, stroke, and Alzheimer's disease. Reviewing the literature suggests that the upregulation of klotho expression regulates various signaling pathways related to autophagy, oxidative stress, inflammation, cognition, and ferroptosis in neurological disorders. Therefore, it has been of great interest to develop drugs or agents that boost or restore klotho levels. In this regard, the present review was designed and aimed to gather the delegated documents regarding the therapeutic potential of Klotho in CNS diseases focusing on the molecular and cellular mechanisms.

KLOTHO KL-VS heterozygosity is associated with diminished age-related neuroinflammation, neurodegeneration, and synaptic dysfunction in older cognitively unimpaired adults

INTRODUCTION

We examined whether the aging suppressor KLOTHO gene's functionally advantageous KL-VS variant (KL-VS heterozygosity [KL-VSHET]) confers resilience against deleterious effects of aging indexed by cerebrospinal fluid (CSF) biomarkers of neuroinflammation (interleukin-6 [IL-6], S100 calcium-binding protein B [S100B], triggering receptor expressed on myeloid cells [sTREM2], chitinase-3-like protein 1 [YKL-40], glial fibrillary acidic protein [GFAP]), neurodegeneration (total α-synuclein [α-Syn], neurofilament light chain protein), and synaptic dysfunction (neurogranin [Ng]).

METHODS

This Alzheimer disease risk-enriched cohort consisted of 454 cognitively unimpaired adults (Mage = 61.5 ± 7.75). Covariate-adjusted multivariate regression examined relationships between age (mean-split[age ≥ 62]) and CSF biomarkers (Roche/NeuroToolKit), and whether they differed between KL-VSHET (N = 122) and non-carriers (KL-VSNC; N = 332).

RESULTS

Older age was associated with a poorer biomarker profile across all analytes (Ps ≤ 0.03). In age-stratified analyses, KL-VSNC exhibited this same pattern (Ps ≤ 0.05) which was not significant for IL-6, S100B, Ng, and α-Syn (Ps ≥ 0.13) in KL-VSHET. Although age-related differences in GFAP, sTREM2, and YKL-40 were evident for both groups (Ps ≤ 0.01), the effect magnitude was markedly stronger for KL-VSNC.

DISCUSSION

Higher levels of neuroinflammation, neurodegeneration, and synaptic dysfunction in older adults were attenuated in KL-VSHET.

HIGHLIGHTS

Older age was associated with poorer profiles across all cerebrospinal fluid biomarkers of neuroinflammation, neurodegeneration, and synaptic dysfunction. KLOTHO KL-VS non-carriers exhibit this same pattern, which is does not significantly differ between younger and older KL-VS heterozygotes for interleukin-6, S100 calcium-binding protein B, neurogranin, and total α-synuclein. Although age-related differences in glial fibrillary acidic protein, triggering receptor expressed on myeloid cells, and chitinase-3-like protein 1 are evident for both KL-VS groups, the magnitude of the effect is markedly stronger for KL-VS non-carriers. Higher levels of neuroinflammation, neurodegeneration, and synaptic dysfunction in older adults are attenuated in KL-VS heterozygotes.

The current and emerging Klotho-enhancement strategies

Klotho is well known as a gene with antiaging properties. It has membrane and soluble forms, providing a unique system that controls various metabolic processes essential to health and disease. Klotho deficiency has been revealed to be associated with various aging-related disorders. Based on its various known and unknown protective properties, upregulating the Klotho gene may be a possible therapeutic and/or preventive approach in aging-related complications. Some agents, such as hormonal compounds, renin-angiotensin system inhibitors, antioxidants, peroxisome proliferator-activated receptor gamma (PPAR-γ) agonists, statins, vitamin D receptor agonists, antioxidants, anti-inflammatory agents, mammalian target of rapamycin (mTOR) signaling inhibitors, and receptor-interacting serine/threonine-protein kinase 1 (RIPK1) inhibitors, can possibly lead to the upregulation and elevation of Klotho levels. Demethylation and deacetylation of the Klotho gene can also be considered other possible Klotho-enhancement methods. Some emerging techniques, such as RNA modifications, gene therapy, gene editing, and exosome therapy, probably have the potential to be applied for increasing Klotho. In the present study, these current and emerging Klotho-enhancement strategies and their underlying mechanisms were comprehensively reviewed, which could highlight some potential avenues for future research.

Novel ligustilide derivatives target quorum sensing system LasR/LasB and relieve inflammatory response against Pseudomonas aeruginosa infection

The increasing antibiotic resistance driven by Pseudomonas aeruginosa typically leads to uncontrolled and persistent inflammatory damage, which is primarily attributed to the virulence and biofilms produced by the bacteria. Herein, we present a novel anti-infective drug strategy designed to inhibit the bacterial quorum sensing system, thereby attenuating P. aeruginosa virulence, and modulating inflammation from drug-resistant bacterial infections. We discovered new quorum sensing LasR/LasB inhibitors derived from the structural modification of a ligustilide derivative library. Of these compounds, 5f demonstrated significant inhibitory activity against LasB (LasB-gfp, IC50 = 8.7 μM) and a moderate inhibitory effect on P. aeruginosa biofilms (IC50 = 7.4 μM). Through live image analysis in a fluorescent protein-labeled zebrafish larva model, we observed that compound 5f significantly inhibited the migration of macrophages. Moreover, compound 5f effectively attenuated quorum sensing-mediated virulence factors and biofilm formation by P. aeruginosa. It also alleviated the inflammatory response by P. aeruginosa-infected macrophages through the downregulation of mitogen-activated protein kinase and NF-κB signal-transduction pathways. Notably, in vivo experiments, this compound demonstrated marked therapeutic effects in acute lung injury models induced by lipopolysaccharides from P. aeruginosa. These results indicate that compound 5f has the potential to be a novel anti-infective candidate against drug-resistant infections caused by P. aeruginosa.

Approaches for Increasing Cerebral Efflux of Amyloid-β in Experimental Systems

Amyloid protein-β (Aβ) concentrations are increased in the brain in both early onset and late onset Alzheimer's disease (AD). In early onset AD, cerebral Aβ production is increased and its clearance is decreased, while increased Aβ burden in late onset AD is due to impaired clearance. Aβ has been the focus of AD therapeutics since development of the amyloid hypothesis, but efforts to slow AD progression by lowering brain Aβ failed until phase 3 trials with the monoclonal antibodies lecanemab and donanemab. In addition to promoting phagocytic clearance of Aβ, antibodies lower cerebral Aβ by efflux of Aβ-antibody complexes across the capillary endothelia, dissolving Aβ aggregates, and a "peripheral sink" mechanism. Although the blood-brain barrier is the main route by which soluble Aβ leaves the brain (facilitated by low-density lipoprotein receptor-related protein-1 and ATP-binding cassette sub-family B member 1), Aβ can also be removed via the blood-cerebrospinal fluid barrier, glymphatic drainage, and intramural periarterial drainage. This review discusses experimental approaches to increase cerebral Aβ efflux via these mechanisms, clinical applications of these approaches, and findings in clinical trials with these approaches in patients with AD or mild cognitive impairment. Based on negative findings in clinical trials with previous approaches targeting monomeric Aβ, increasing the cerebral efflux of soluble Aβ is unlikely to slow AD progression if used as monotherapy. But if used as an adjunct to treatment with lecanemab or donanemab, this approach might allow greater slowing of AD progression than treatment with either antibody alone.

The Extract of Angelica sinensis Inhibits Hypoxia-Reoxygenation and Copper-Induced Oxidative Lesions and Apoptosis in Branchiae and Red Blood Corpuscles of Fish

The study explored the effects of Angelica sinensis extract (AsE) on oxidative lesions and apoptosis in branchiae and red blood corpuscles in hypoxia-reoxygenation (HR) and Cu-treated carp (Cyprinus carpio var. Jian). After feeding trial for 30 days, the carp were exposed to HR and CuSO4. The results indicated that dietary AsE increased the durative time, decreased the oxygen consumption rate, suppressed ROS generation and cellular component oxidation, decreased enzymatic antioxidant activity and reduced glutathione (GSH) levels in red blood corpuscles and branchiae in carp under hypoxia. Moreover, dietary AsE avoided the loss of Na+,K+-ATPase, metabolic and antioxidant enzyme activities, ROS generation and cellular component oxidation, as well as the increase in caspase-8, 9, and 3 activities in the branchiae of the carp and inhibited ROS generation. It furthermore avoided the loss of Na+,K+-ATPase and metabolic enzyme activities, the decrease in GSH levels and hemoglobin content, the increase in the activities of caspase-8, 9, and 3 and the increase in the levels of cytochrome c and phosphatidylserine exposure in the red blood corpuscles of Cu-exposed carp. The present results suggested that dietary AsE improved hypoxia tolerance and inhibited HR or Cu-triggered oxidative lesions and apoptosis. Therefore, AsE can be utilized as a natural inhibitor of Cu and HR stress in fish.

The possible anti-seizure properties of Klotho

Recurrent seizures in epilepsy may lead to progressive neuronal damage, which can diminish health-related quality of life. Evaluation and control of pathological processes in the brain is valuable. It seems imperative that new markers and approaches for seizure alleviation be discovered. Klotho (Kl), an antiaging protein, has protective effects in the brain against neurological disorders. It may also have antiseizure effects by improving creatine transfer to the brain, upregulating excitatory amino acid transporters, and inhibiting insulin/insulin-like growth factor-1 (IGF-1), Wingless (Wnt), transforming growth factor-beta (TGF-β), and retinoic-acid-inducible gene-I (RIG-I)/nuclear translocation of nuclear factor-κB (NF-κB) pathways. Stimulation and activation of the nuclear factor erythroid 2-related factor 2 (Nrf2) and apoptosis signal-regulating kinase 1 (ASK1)/p38 mitogen‑activated protein kinase (MAPK) signaling pathways could also be considered other possible antiseizure mechanisms of Kl. In the present review, the roles of Kl in the central nervous system as well as its possible anti-seizure properties are discussed for the first time.

Klotho inhibits IGF1R/PI3K/AKT signalling pathway and protects the heart from oxidative stress during ischemia/reperfusion injury

Ischemia/reperfusion injury (IRI) of the heart involves the activation of oxidative and proapoptotic pathways. Simultaneously Klotho protein presents anti-aging, antiapoptotic and antioxidative properties. Therefore, this study aimed to evaluate the effect of Klotho protein on oxidative stress in hearts subjected to IRI. Isolated rat hearts perfused with the Langendorff method were subjected to ischemia, followed by reperfusion, in the presence or absence of recombinant rat Klotho protein. The factors involved in the activation of insulin-like growth factor receptor (IGF1R)/phosphoinositide-3-kinase (PI3K)/protein kinase B (AKT) signalling pathway were evaluated. IRI caused activation of the IGF1R (p = 0.0122)/PI3K (p = 0.0022) signalling, as compared to the aerobic control group. Infusion supply of Klotho protein during IRI significantly reduced the level of phospho-IGF1R (p = 0.0436), PI3K (p = 0.0218) and phospho-AKT (p = 0.0020). Transcriptional activity of forkhead box protein O3 (FOXO3) was reduced (p = 0.0207) in hearts subjected to IRI, compared to aerobic control. Administration of Klotho decreased phosphorylation of FOXO3 (p = 0.0355), and enhanced activity of glutathione peroxidase (p = 0.0452) and superoxide dismutase (p = 0.0060) in IRI + Klotho group. The levels of reactive oxygen/nitrogen species (ROS/RNS) (p = 0.0480) and hydrogen peroxide (H2O2) (p = 0.0460), and heart injury (p = 0.0005) were significantly increased in hearts from the IRI group in comparison to the aerobic group. Klotho reduced NADPH oxidase 2 (NOX2) (p = 0.0390), ROS/RNS (p = 0.0435) and H2O2 (p = 0.0392) levels, and heart damage (p = 0.0286) in the hearts subjected to IRI. In conclusion, Klotho contributed to the protection of the heart against IRI and oxidative stress via inhibition of the IGF1R/PI3K/AKT pathway, thus can be recognized as a novel cardiopreventive/cardioprotective agent.

Therapeutic Potential of P110 Peptide: New Insights into Treatment of Alzheimer's Disease

Mitochondrial degeneration in various neurodegenerative diseases, specifically in Alzheimer's disease, involves excessive mitochondrial fission and reduced fusion, leading to cell damage. P110 is a seven-amino acid peptide that restores mitochondrial dynamics by acting as an inhibitor of mitochondrial fission. However, the role of P110 as a neuroprotective agent in AD remains unclear. Therefore, we performed cell culture studies to evaluate the neuroprotective effect of P110 on amyloid-β accumulation and mitochondrial functioning. Human SH-SY5Y neuronal cells were incubated with 1 µM and 10 µM of P110, and Real-Time PCR and Western blot analysis were done to quantify the expression of genes pertaining to AD and neuronal health. Exposure of SH-SY5Y cells to P110 significantly increased APP mRNA levels at 1 µM, while BACE1 mRNA levels were increased at both 1 µM and 10 µM. However, protein levels of both APP and BACE1 were significantly reduced at 10 µM of P110. Further, P110 treatment significantly increased ADAM10 and Klotho protein levels at 10 µM. In addition, P110 exposure significantly increased active mitochondria and reduced ROS in live SH-SY5Y cells at both 1 µM and 10 µM concentrations. Taken together, our results indicate that P110 might be useful in attenuating amyloid-β generation and improving neuronal health by maintaining mitochondrial function in neurons.

FoxO1 as a tissue-specific therapeutic target for type 2 diabetes

Forkhead box O (FoxO) proteins are transcription factors that mediate many aspects of physiology and thus have been targeted as therapeutics for several diseases including metabolic disorders such as type 2 diabetes mellitus (T2D). The role of FoxO1 in metabolism has been well studied, but recently FoxO1's potential for diabetes prevention and therapy has been debated. For example, studies have shown that increased FoxO1 activity in certain tissue types contributes to T2D pathology, symptoms, and comorbidities, yet in other tissue types elevated FoxO1 has been reported to alleviate symptoms associated with diabetes. Furthermore, studies have reported opposite effects of active FoxO1 in the same tissue type. For example, in the liver, FoxO1 contributes to T2D by increasing hepatic glucose production. However, FoxO1 has been shown to either increase or decrease hepatic lipogenesis as well as adipogenesis in white adipose tissue. In skeletal muscle, FoxO1 reduces glucose uptake and oxidation, promotes lipid uptake and oxidation, and increases muscle atrophy. While many studies show that FoxO1 lowers pancreatic insulin production and secretion, others show the opposite, especially in response to oxidative stress and inflammation. Elevated FoxO1 in the hypothalamus increases the risk of developing T2D. However, increased FoxO1 may mitigate Alzheimer's disease, a neurodegenerative disease strongly associated with T2D. Conversely, accumulating evidence implicates increased FoxO1 with Parkinson's disease pathogenesis. Here we review FoxO1's actions in T2D conditions in metabolic tissues that abundantly express FoxO1 and highlight some of the current studies targeting FoxO1 for T2D treatment.

Differential regulation of hippocampal transcriptome by circulating estrogen

Estrogen (E2) modulates the synaptic structure and plasticity in the hippocampus. Previous studies showed that E2 fluctuations during various phases of the menstrual cycle produce subtle neurosynaptic changes that impact women's behavior, emotion, and cognitive functions. In this study, we explored the transcriptome of the hippocampus via RNA-seq (RNA-sequencing) between proestrus (PE) and diestrus (DE) stages in young female rats to determine the effect of E2 of PE and DE stages on hippocampal gene expression. We identified 238 genes (at 1.5-fold-change selection criteria, FDR adjusted p-value < 0.05) as differentially expressed genes (DEGs) that responded to E2 between PE and DE stages. Functional analysis based on Gene Ontology (GO) revealed that a higher E2 level corresponded to an increase in gene transcription among most of the DEGs, suggesting biological mechanisms operating differentially in the hippocampus of female rats between PE and DE stages in the estrus cycle; while analysis with Kyoto Encyclopedia of Genes and Genomes database (KEGG) found that the DEGs involving neuroactive ligand-receptor interaction, antigen processing, cell adhesion molecules, and presentation were upregulated in PE stage, whereas DEGs in pathways relating to bile secretion, coagulation cascades, osteoclast differentiation, cysteine and methionine metabolism were upregulated in DE stage of the estrus cycle. The high-fold expression of DEGs was confirmed by a follow-up quantitative real-time PCR. Our findings in this current study have provided fundamental information for further dissection of neuro-molecular mechanisms in the hippocampus in response to E2 fluctuation and its relationship with disorders.

Relationships between serum Klotho concentrations and cognitive performance among older chronic kidney disease patients with albuminuria in NHANES 2011-2014

Background

The potential relationship between Klotho and cognitive function is limited and controversial. This study aimed to quantify the association of Klotho and cognitive impairment in chronic kidney disease (CKD) patients with albuminuria.

Methods

Serum Klotho was measured by enzyme-linked immunosorbent assay. Patients with urine albumin to creatinine ratio (UACR) > 30mg/g from the National Health and Nutrition Survey (NHANES) 2011-2014 were divided into 4 groups according to the quartile of Klotho. Cognitive function was examined using the Consortium to Establish a Registry for Alzheimer's Disease (CERAD), Digit Symbol Substitution Test (DSST), and Animal Fluency Test. The relationship between Klotho and cognitive function was analyzed by multivariable regression and subgroup analysis.

Results

Among 368 CKD patients with albuminuria, we found that Klotho was negatively associated with creatinine, and positively associated with hemoglobin, and estimated glomerular filtration rate. No significant linear relationship was showed between Klotho (as a continuous variable) and cognitive function. When regarded Klotho as a category variable, patients in the quartile 3 group were at a better cognitive performance for CEARD-word learning subset and DSST, especially in the CKD patients with 30 mg/g < UACR <300 mg/g, but not in participants with UACR > 300 mg/g.

Conclusions

The increased Klotho was associated with an increased cognitive function in CKD patients with microalbuminuria. Further studies are needed to demonstrate whether Klotho may be a beneficial biomarker of cognitive health and neurodegeneration.

Neuroprotective Role of Klotho on Dementia

Klotho, a gene found on chromosome 13q12, is involved in a variety of processes and signaling pathways in the human body related to vitamin D metabolism; cardiovascular, renal, musculoskeletal, and skin diseases; and cancer biology. However, more importantly, it has been linked to beneficial effects related to anti-aging. The levels of soluble Klotho in the blood have been found to decline with age, increasing the risk of age-related diseases. When the Klotho gene was silenced or defective, it caused a shorter lifespan. However, when the gene was overexpressed, it resulted in a longer lifespan. Klotho has positive benefits on the neurological system by causing a higher representation of useful longevity genes, preventing further neuronal damage, and offering neuroprotection. Thus, it has the potential to become a new treatment for many age-related diseases that cause dementia, including multiple sclerosis, Alzheimer's disease, and Parkinson's disease. In this review, we discuss the mechanisms of Klotho's benefits and roles on various organ systems, specifically on nervous system disorders that lead to dementia.

Novel approaches to increase synaptic resilience as potential treatments for Alzheimer's disease

A significant proportion of brains with Alzheimer's disease pathology are obtained from patients that were cognitively normal, suggesting that differences within the brains of these individuals made them resilient to the disease. Here, we describe recent approaches that specifically increase synaptic resilience, as loss of synapses is considered to be the first change in the brains of Alzheimer's patients. We start by discussing studies showing benefit from increased expression of neurotrophic factors and protective genes. Methods that effectively make dendritic spines stronger, specifically by acting through actin network proteins, scaffolding proteins and inhibition of phosphatases are described next. Importantly, the therapeutic strategies presented in this review tackle Alzheimer's disease not by targeting plaques and tangles, but instead by making synapses resilient to the pathology associated with Alzheimer's disease, which has tremendous potential.

Klotho Upregulation via PPARγ Contributes to the Induction of Brain Ischemic Tolerance by Cerebral Ischemic Preconditioning in Rats

Cerebral ischemic preconditioning (CIP)-induced brain ischemic tolerance protects neurons from subsequent lethal ischemic insult. However, the specific mechanisms underlying CIP remain unclear. In the present study, we explored the hypothesis that peroxisome proliferator-activated receptor gamma (PPARγ) participates in the upregulation of Klotho during the induction of brain ischemic tolerance by CIP. First we investigated the expression of Klotho during the brain ischemic tolerance induced by CIP. Lethal ischemia significantly decreased Klotho expression from 6 h to 7 days, while CIP significantly increased Klotho expression from 12 h to 7 days in the hippocampal CA1 region. Inhibition of Klotho expression by its shRNA blocked the neuroprotection induced by CIP. These results indicate that Klotho participates in brain ischemic tolerance by CIP. Furthermore, we tested the role of PPARγ in regulating Klotho expression after CIP. CIP caused PPARγ protein translocation to the nucleus in neurons in the CA1 region of the hippocampus. Pretreatment with GW9962, a PPARγ inhibitor, significantly attenuated the upregulation of Klotho protein and blocked the brain ischemic tolerance induced by CIP. Taken together, it can be concluded that Klotho upregulation via PPARγ contributes to the induction of brain ischemic tolerance by CIP.

The relationship between serum klotho and cognitive performance in a nationally representative sample of US adults

Purpose

Aging is the primary risk factor for cognitive decline. Serum klotho, as an anti-aging protein, may be involved in cognitive decline. Thus, we aim to explorer the correlation between serum klotho and cognitive performance among an older adult population in the United States.

Methods

We performed a cross-sectional study using data from NHANES 2011-2014. Serum klotho was analyzed by ELISA. Cognitive function was measured by Establish a Registry for Alzheimer's Disease (CERAD) test, Animal Fluency test and Digit Symbol Substitution Test (DSST) score. The relationship between serum klotho and cognition was analyzed by a multivariable regression model.

Results

A total of 2,171 participants aged 60-79 years were included. Median serum klotho concentration was 851.52 pg./ml (SD = 294.07). We also categorized serum klotho concentrates into quartiles. After fully adjusting pertinent variables, compared to those with lowest klotho levels (206.3-658.4 pg./ml), individuals with highest klotho concentrates (983.3-3,456 pg./ml) had a higher CERAD score [β (95%CI): 0.97 (0.25, 1.69) p = 0.008] and DSST score [β (95%CI): 1.86 (0.25, 3.47), p = 0.024].

Conclusion

Our findings indicated that, among the general population of American older adults, serum klotho concentrates may serve as a marker of cognitive health. The benefits of klotho on aging process and neurodegenerative disorders should be paid more attention.

Klotho, Oxidative Stress, and Mitochondrial Damage in Kidney Disease

Reducing oxidative stress stands at the center of a prevention and control strategy for mitigating cellular senescence and aging. Kidney disease is characterized by a premature aging syndrome, and to find a modulator targeting against oxidative stress, mitochondrial dysfunction, and cellular senescence in kidney cells could be of great significance to prevent and control the progression of this disease. This review focuses on the pathogenic mechanisms related to the appearance of oxidative stress damage and mitochondrial dysfunction in kidney disease. In this scenario, the anti-aging Klotho protein plays a crucial role by modulating signaling pathways involving the manganese-containing superoxide dismutase (Mn-SOD) and the transcription factors FoxO and Nrf2, known antioxidant systems, and other known mitochondrial function regulators, such as mitochondrial uncoupling protein 1 (UCP1), B-cell lymphoma-2 (BCL-2), Wnt/β-catenin, peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1 alpha), transcription factor EB, (TFEB), and peroxisome proliferator-activated receptor gamma (PPAR-gamma). Therefore, Klotho is postulated as a very promising new target for future therapeutic strategies against oxidative stress, mitochondria abnormalities, and cellular senescence in kidney disease patients.

AD-associated CSF biomolecular changes are attenuated in KL-VS heterozygotes

Introduction

Dementia as an inevitable aging consequence has been challenged and underscores the need for investigations of the factors that confer resilience. We examine whether the functionally advantageous KL-VS variant of the putative aging suppressor KLOTHO gene attenuates age-related cognitive decline and deleterious biomolecular changes.

Methods

Trajectories of change in memory and executive function (N = 360; 2-12 visits) and cerebrospinal fluid (CSF) Alzheimer's disease (AD) biomarkers-amyloid beta (Aβ)42, total tau (t-tau), phosphorylated tau (p-tau) (N = 112; 2-4 samplings)-were compared between KL-VS non-carriers and heterozygotes in middle-aged and older adults from the Wisconsin Registry for Alzheimer's Prevention and the Wisconsin Alzheimer's Disease Research Center studies.

Results

Memory and executive function declined (p's≤ 0.001) and CSF t-tau, p-tau, t-tau/Aβ42, and p-tau/Aβ42 levels increased (all p's≤ 0.004) with age. The rate of p-tau accumulation was attenuated for KL-VS heterozygotes (p = 0.03).

Discussion

KL-VS heterozygosity may confer resilience to AD-associated biomolecular changes.

Artichoke (Cynara Scolymus) Methanolic Leaf Extract Alleviates Diethylnitrosamine-Induced Toxicity in BALB/c Mouse Brain: Involvement of Oxidative Stress and Apoptotically Related Klotho/PPARγ Signaling

(1) Background: Various epidemiological studies suggest that oxidative stress and disrupted neuronal function are mechanistically linked to neurodegenerative diseases (NDs), including Parkinson's disease (PD) and Alzheimer's disease (AD). DNA damage, oxidative stress, lipid peroxidation, and eventually, cell death such as NDs can be induced by nitrosamine-related compounds, leading to neurodegeneration. A limited number of studies have reported that exposure to diethylnitrosamine (DEN), which is commonly found in processed/preserved foods, causes biochemical abnormalities in the brain. Artichoke leaves have been used in traditional medicine as a beneficial source of bioactive components such as hydroxycinnamic acids, cynarine, chlorogenic acid, and flavonoids (luteolin and apigenin). The aim of this study is to investigate the favorable effects of exogenous artichoke (Cynara scolymus) methanolic leaf extract supplementation in ameliorating DEN-induced deleterious effects in BALB/c mouse brains. (2) Methods: This study was designed to evaluate DEN (toxicity induction by 100 mg/kg) and artichoke (protective effects of 0.8 and 1.6 g/kg treatment) for 14 days. All groups underwent a locomotor activity test to evaluate motor activity. In brain tissue, oxidative stress indicators (TAC, TOS, and MDA), Klotho and PPARγ levels, and apoptotic markers (Bax, Bcl-2, and caspase-3) were measured. Brain slices were also examined histopathologically. (3) Results: Artichoke effectively ameliorated DEN-induced toxicity with increasing artichoke dose. Impaired motor function and elevated oxidative stress markers (decreasing MDA and TOS levels and increasing TAC level) induced by DEN intoxication were markedly restored by high-dose artichoke treatment. Artichoke significantly improved the levels of Klotho and PPARγ, which are neuroprotective factors, in mouse brain tissue exposed to DEN. In addition, caspase-3 and Bax levels were reduced, whereas the Bcl-2 level was elevated with artichoke treatment. Furthermore, recovery was confirmed by histopathological analysis. (4) Conclusions: Artichoke exerted neuroprotective effects against DEN-induced brain toxicity by mitigating oxidant parameters and exerting antioxidant and antiapoptotic effects. Further research is needed to fully identify the favorable impact of artichoke supplementation on all aspects of DEN brain intoxication.

KL-FGF23-VD Axis in Improving Late-Onset Alzheimer's Disease by Modulating IKK/NF-κB Signal Pathway

Materials and Methods

LOAD rats and Aβ microglia were constructed by using Aβ 1-40 and IBO mixture. The effect of KL-FGF23-VD axis on LOAD was investigated by transfecting overexpressing and interfering with KL gene adenovirus, and IKK-16 was added to Aβ microglia to explore the effect of KL-FGF23-VD axis on regulation of IKK/NF-κB signaling pathway.

Results

The results showed that, in KL-OE group, FGF23 was decreased in the hippocampus of LOAD rats compared with control and KL-si, and the trend was opposite in the KL-si group. The KL-FGF23-VD axis can alleviate inflammatory response, reduce the deposition of Aβ, and inhibit activation of the NF-κB pathway and neuron apoptosis in brain tissue of LOAD rats. In Aβ microglia, the expression of KL-FGF23-VD axis was consistent with animal experiments. The KL-FGF23-VD axis can inhibit the expression of Aβ microglia inflammatory factors and the activation of microglia and NF-κB pathway. Meanwhile, IKK expression was decreased in KL-OE group compared with KL-si and Control. In the IKK-16 addition group, the ability of KL-FGF23-VD axis to inhibit the activation of microglia and NF-κB pathway was enhanced.

Conclusions

These findings suggest a potential role of the KL-FGF23-VD axis in AD treatment by regulating the IKK/NF-κB pathway.

Medicine-food herb: Angelica sinensis, a potential therapeutic hope for Alzheimer's disease and related complications

Alzheimer's disease (AD) is a progressive neurodegenerative disease, which has brought a huge burden to the world. The current therapeutic approach of one-molecule-one-target strategy fails to address the issues of AD because of multiple pathological features of AD. Traditionally, the herb of Angelica sinensis (AS) comes from the root of an umbrella plant Angelica sinensis (Oliv.) Diels. As a typical medicine-food herb, studies have shown that AS can alleviate AD and AD-complications by multiple targets through the various foundations of pharmaceutical material and dietary supply basis. Therefore, this review summarizes the pharmacological effects of AS for the treatment of AD and AD-complications for the first time. AS contains many effective components, such as ligustilide, z-ligustilide, n-butylidenephthalide, α-pinene, p-cymene, myrcene, ferulic acid, vanillic acid and coniferyl ferulate. It is found that AS, AS-active compounds and AS-compound recipes mainly treat AD through neuroprotective, anti-inflammation, and anti-oxidant effects, improving mitochondrial dysfunction, anti-neuronal apoptosis, regulating autophagy, regulating intestinal flora and enhancing the central cholinergic system, which shows the multi-component and multi-target effect of AS. The role of dietary supplement components in AS for AD intervention is summarized, including vitamin B₁₂, folic acid, arginine, and oleic acid, which can improve the symptoms of AD. Besides, this review focuses on the safety and toxicity evaluation of AS, which provides a basis for its application. This review will provide further support for the research on AD and the application of medicine-food herb AS in a healthy lifestyle in the future.

Pathobiology of the Klotho Antiaging Protein and Therapeutic Considerations

The α-Klotho protein (henceforth denoted Klotho) has antiaging properties, as first observed in mice homozygous for a hypomorphic Klotho gene (kl/kl). These mice have a shortened lifespan, stunted growth, renal disease, hyperphosphatemia, hypercalcemia, vascular calcification, cardiac hypertrophy, hypertension, pulmonary disease, cognitive impairment, multi-organ atrophy and fibrosis. Overexpression of Klotho has opposite effects, extending lifespan. In humans, Klotho levels decline with age, chronic kidney disease, diabetes, Alzheimer’s disease and other conditions. Low Klotho levels correlate with an increase in the death rate from all causes. Klotho acts either as an obligate coreceptor for fibroblast growth factor 23 (FGF23), or as a soluble pleiotropic endocrine hormone (s-Klotho). It is mainly produced in the kidneys, but also in the brain, pancreas and other tissues. On renal tubular-cell membranes, it associates with FGF receptors to bind FGF23. Produced in bones, FGF23 regulates renal excretion of phosphate (phosphaturic effect) and vitamin D metabolism. Lack of Klotho or FGF23 results in hyperphosphatemia and hypervitaminosis D. With age, human renal function often deteriorates, lowering Klotho levels. This appears to promote age-related pathology. Remarkably, Klotho inhibits four pathways that have been linked to aging in various ways: Transforming growth factor β (TGF-β), insulin-like growth factor 1 (IGF-1), Wnt and NF-κB. These can induce cellular senescence, apoptosis, inflammation, immune dysfunction, fibrosis and neoplasia. Furthermore, Klotho increases cell-protective antioxidant enzymes through Nrf2 and FoxO. In accord, preclinical Klotho therapy ameliorated renal, cardiovascular, diabetes-related and neurodegenerative diseases, as well as cancer. s-Klotho protein injection was effective, but requires further investigation. Several drugs enhance circulating Klotho levels, and some cross the blood-brain barrier to potentially act in the brain. In clinical trials, increased Klotho was noted with renin-angiotensin system inhibitors (losartan, valsartan), a statin (fluvastatin), mTOR inhibitors (rapamycin, everolimus), vitamin D and pentoxifylline. In preclinical work, antidiabetic drugs (metformin, GLP-1-based, GABA, PPAR-γ agonists) also enhanced Klotho. Several traditional medicines and/or nutraceuticals increased Klotho in rodents, including astaxanthin, curcumin, ginseng, ligustilide and resveratrol. Notably, exercise and sport activity increased Klotho. This review addresses molecular, physiological and therapeutic aspects of Klotho.

A Review of Traditional Chinese Medicine, Buyang Huanwu Decoction for the Treatment of Cerebral Small Vessel Disease

Cerebral small vessel disease (CSVD) is often referred to as “collaterals disease” in traditional Chinese medicine (TCM), and commonly includes ischemic and hemorrhagic CSVD. TCM has a long history of treating CSVD and has demonstrated unique efficacy. Buyang Huanwu Decoction (BHD) is a classical TCM formula that has been used for the prevention and treatment of stroke for hundreds of years. BHD exerts its therapeutic effects on CSVD through a variety of mechanisms. In this review, the clinical and animal studies on BHD and CSVD were systematically introduced. In addition, the pharmacological mechanisms, active components, and clinical applications of BHD in the treatment of CSVD were reviewed. We believe that an in-depth understanding of BHD, its pharmacological mechanism, disease-drug interaction, and other aspects will help in laying the foundation for its development as a new therapeutic strategy for the treatment of CSVD.

Circadian disruption of hippocampus in an early senescence male mouse model

Age-related cognitive decline and disruptions in circadian rhythms are growing problems as the average human life span increases. Multiple strains of the senescence-accelerated mouse (SAM) show reduced life span, and the SAMP8 strain in particular has been well documented to show cognitive deficits in behavior as well as a bimodal pattern of circadian locomotor activity. However, little is known about circadian regulation within the hippocampus of these strains of mice. Here we test the hypothesis that in this early senescence model, disruption of the molecular circadian clock in SAMP8 animals drives disrupted behavior and physiology. We found normal rhythms in PER2 protein expression in the SCN of SAMP8 animals at 4 months, despite the presence of disrupted wheel-running activity rhythms at this age. Interestingly, a significant rhythm in PER2 expression was not observed in the hippocampus of SAMP8 animals, despite a significant 24-h rhythm in SAMR1 controls. We also examined time-restricted feeding as a potential strategy to rescue disrupted hippocampal plasticity. Time-restricted feeding increased long-term potentiation at Schaffer collateral-CA1 synapses in SAMP8 mice (compared to SAMR1 controls). Overall, we confirm disrupted circadian locomotor rhythms in this early senescence model (as early as 4 months) and discovered that this disruption is not due to arrhythmic PER2 levels in the SCN; however, other extra-SCN circadian oscillators (i.e., hippocampus) are likely impaired with accelerated aging.

Trimethylamine N-Oxide (TMAO) drives insulin resistance and cognitive deficiencies in a senescence accelerated mouse model

It has been established that ageing is the major risk factor for cognitive deficiency and it is becoming increasingly evident that insulin resistance is another factor. Biological plausibility for a link between insulin resistance and dementia is relevant for understanding disease etiology, and to form bases for prevention efforts to decrease disease burden. In the present study, peripheral and central insulin resistance was found in SAMP8 mice (aging mouse model) accompanied by cognitive deficiencies. Furthermore, a marked peripheral inflammatory state was observed in SAMP8 mice, followed by neuroinflammation that could be due to a higher cytokine leaking into the brain across an aging-disrupted blood brain barrier. Moreover, aging-induced gut dysbiosis produces higher TMAO that could also contribute to the peripheral and central inflammatory tone as well as to the cognitive deficiencies observed in SAMP8 mice. All those alterations were reversed by DMB, a treatment that decreases TMAO levels. Data obtained from this project suggest that microbial dysbiosis and increased TMAO secretion could be a key link between aging, insulin resistance and dementia. Thus, pharmacological intervention that leads to decreased TMAO levels, such as DMB, could open a new avenue for the future treatment of neurodegenerative diseases.

Klotho an Autophagy Stimulator as a Potential Therapeutic Target for Alzheimer’s Disease: A Review

Alzheimer’s disease (AD) is an age-associated neurodegenerative disease; it is the most common cause of senile dementia. Klotho, a single-pass transmembrane protein primarily generated in the brain and kidney, is active in a variety of metabolic pathways involved in controlling neurodegeneration and ageing. Recently, many studies have found that the upregulation of Klotho can improve pathological cognitive deficits in an AD mice model and have demonstrated that Klotho plays a role in the induction of autophagy, a major contributing factor for AD. Despite the close association between Klotho and neurodegenerative diseases, such as AD, the underlying mechanism by which Klotho contributes to AD remains poorly understood. In this paper, we will introduce the expression, location and structure of Klotho and its biological functions. Specifically, this review is devoted to the correlation of Klotho protein and the AD phenotype, such as the effect of Klotho in upregulating the amyloid-beta clearance and in inducing autophagy for the clearance of toxic proteins, by regulating the autophagy lysosomal pathway (ALP). In summary, the results of multiple studies point out that targeting Klotho would be a potential therapeutic strategy in AD treatment.

Selective Secretase Targeting for Alzheimer's Disease Therapy

Alzheimer's disease (AD) is associated with marked atrophy of the cerebral cortex and accumulation of amyloid plaques and neurofibrillary tangles. Amyloid plaques are formed by oligomers of amyloid-β (Aβ) in the brain, with a length of 42 and 40 amino acids. α-secretase cleaves amyloid-β protein precursor (AβPP) producing the membrane-bound fragment CTFα and the soluble fragment sAβPPα with neuroprotective activity; β-secretase produces membrane-bound fragment CTFβ and a soluble fragment sAβPPβ. After α-secretase cleavage of AβPP, γ-secretase cleaves CTFα to produce the cytoplasmic fragment AICD and P3 in the non-amyloidogenic pathway. CTFβ is cleaved by γ-secretase producing AICD as well as Aβ in amyloidogenic pathways. In the last years, the study of natural products and synthetic compounds, such as α-secretase activity enhancers, β-secretase inhibitors (BACE-1), and γ-secretase activity modulators, have been the focus of pharmaceuticals and researchers. Drugs were improved regarding solubility, blood-brain barrier penetration, selectivity, and potency decreasing Aβ42. In this regard, BACE-1 inhibitors, such as Atabecestat, NB-360, Umibecestat, PF-06751979 Verubecestat, LY2886721, Lanabecestat, LY2811376 and Elenbecestat, were submitted to phase I-III clinical trials. However, inhibition of Aβ production did not recover cognitive functions or reverse disease progress. Novel strategies are being developed, aiming at a partial reduction of Aβ production, such as the development of γ-secretase modulators or α-secretase activity enhancers. Such therapeutic tools shall focus on slowing down or minimizing the progression of neuronal damage. Here, we summarize structures and activities of the latest compounds designed for AD treatment, with remarkable in vitro, in vivo, and clinical phase activities.

KL-VS heterozygosity is associated with lower amyloid-dependent tau accumulation and memory impairment in Alzheimer's disease

Klotho-VS heterozygosity (KL-VS^het) is associated with reduced risk of Alzheimer’s disease (AD). However, whether KL-VS^het is associated with lower levels of pathologic tau, i.e., the key AD pathology driving neurodegeneration and cognitive decline, is unknown. Here, we assessed the interaction between KL-VS^het and levels of beta-amyloid, a key driver of tau pathology, on the levels of PET-assessed neurofibrillary tau in 551 controls and patients across the AD continuum. KL-VS^het showed lower cross-sectional and longitudinal increase in tau-PET per unit increase in amyloid-PET when compared to that of non-carriers. This association of KL-VS^het on tau-PET was stronger in Klotho mRNA-expressing brain regions mapped onto a gene expression atlas. KL-VS^het was related to better memory functions in amyloid-positive participants and this association was mediated by lower tau-PET. Amyloid-PET levels did not differ between KL-VS^het carriers versus non-carriers. Together, our findings provide evidence to suggest a protective role of KL-VS^het against amyloid-related tau pathology and tau-related memory impairments in elderly humans at risk of AD dementia.

The KL-VS haplotype of the Klotho gene has been associated with reduced risk of Alzheimer’s disease and dementia. Here the authors show an association between the KL-VS haplotype and amyloid-dependent tau accumulation using PET data.

Exploiting the neuroprotective effects of α-klotho to tackle ageing- and neurodegeneration-related cognitive dysfunction

Cognitive dysfunction is a key symptom of ageing and neurodegenerative disorders, such as Alzheimer's disease (AD). Strategies to enhance cognition would impact the quality of life for a significant proportion of the ageing population. The α-klotho protein may protect against cognitive decline through multiple mechanisms: such as promoting optimal synaptic function via activation of N-methyl-d-aspartate (NMDA) receptor signalling; stimulating the antioxidant defence system; reducing inflammation; promoting autophagy and enhancing clearance of amyloid-β. However, the molecular and cellular pathways by which α-klotho mediates these neuroprotective functions have yet to be fully elucidated. Key questions remain unanswered: which form of α-klotho (transmembrane, soluble or secreted) mediates its cognitive enhancing properties; what is the neuronal receptor for α-klotho and which signalling pathways are activated by α-klotho in the brain to enhance cognition; how does peripherally administered α-klotho mediate neuroprotection; and what is the molecular basis for the beneficial effect of the VS variant of α-klotho? In this review, we summarise the recent research on neuronal α-klotho and discuss how the neuroprotective properties of α-klotho could be exploited to tackle age- and neurodegeneration-associated cognitive dysfunction.

SAMP8 Mice as a Model of Age-Related Cognition Decline with Underlying Mechanisms in Alzheimer's Disease

Alzheimer's disease (AD) is a highly age-related cognitive decline frequently attacking the elderly. Senescence-accelerated mouse-prone 8 (SAMP8) is an ideal model to study AD, displaying age-related learning and memory disorders. SAMP8 mice exhibit most features of pathogenesis of AD, including an abnormal expression of anti-aging factors, oxidative stress, inflammation, amyloid-β (Aβ) deposits, tau hyperphosphorylation, endoplasmic reticulum stress, abnormal autophagy activity, and disruption of intestinal flora. SAMP8 mice, therefore, have visualized the understanding of AD, and also provided effective ways to find new therapeutic targets. This review focused on the age-related pathogenesis in SAMP8 mice, to advance the understanding of age-related learning and memory decline and clarify the mechanisms. Furthermore, this review will provide extensive foundations for SAMP8 mice used in therapeutics for AD.

Klotho, PTSD, and advanced epigenetic age in cortical tissue

This study examined the klotho (KL) longevity gene polymorphism rs9315202 and psychopathology, including posttraumatic stress disorder (PTSD), depression, and alcohol-use disorders, in association with advanced epigenetic age in three postmortem cortical tissue regions: dorsolateral and ventromedial prefrontal cortices and motor cortex. Using data from the VA National PTSD Brain Bank (n = 117), we found that rs9315202 interacted with PTSD to predict advanced epigenetic age in motor cortex among the subset of relatively older (>=45 years), white non-Hispanic decedents (corrected p = 0.014, n = 42). An evaluation of 211 additional common KL variants revealed that only variants in linkage disequilibrium with rs9315202 showed similarly high levels of significance. Alcohol abuse was nominally associated with advanced epigenetic age in motor cortex (p = 0.039, n = 114). The rs9315202 SNP interacted with PTSD to predict decreased KL expression via DNAm age residuals in motor cortex among older white non-Hispanics decedents (indirect β = -0.198, p = 0.027). Finally, in dual-luciferase enhancer reporter system experiments, we found that inserting the minor allele of rs9315202 in a human kidney cell line HK-2 genomic DNA resulted in a change in KL transcriptional activities, likely operating via long noncoding RNA in this region. This was the first study to examine multiple forms of psychopathology in association with advanced DNA methylation age across several brain regions, to extend work concerning the association between rs9315202 and advanced epigenetic to brain tissue, and to identify the effects of rs9315202 on KL gene expression. KL augmentation holds promise as a therapeutic intervention to slow the pace of cellular aging, disease onset, and neuropathology, particularly in older, stressed populations.

Age-related cognitive decline is associated with microbiota-gut-brain axis disorders and neuroinflammation in mice

Age-related cognitive decline is associated with chronic low grade neuroinflammation that may result from a complex interplay among many factors, such as bidirectional communication between the central nervous system (CNS) and gut microbiota. The present study used 2-month-old (young group) and 15-month-old (aged group) male C57BL/6 mice to explore the potential association between age-related cognitive decline and the microbiota-gut-brain axis disorder. We observed that aged mice exhibited significant deficits in learning and memory, neuronal and synaptic function compared with young mice. Aged mice also exhibited significant dysbiosis of the gut microbiota. Disruptions of the intestinal barrier and blood-brain barrier were also observed, including increases in intestinal, low-grade systemic and cerebral inflammation. Furthermore, plasma and brain levels of lipopolysaccharide (LPS) were significantly higher in aged mice compared with young mice, with increasing expression of Toll-like receptor 4 (TLR4) and myeloid differential protein-88 (MyD88) and the nuclear translocation of nuclear factor κB (NF-κB) in intestinal and brain tissues. These findings showed that microbiota-gut-brain axis dysfunction that occurs through LPS-induced activation of the TLR4/NF-κB signaling pathway is implicated in age-related neuroinflammation and cognitive decline.

Neuroprotective effects of vildagliptin on drug induced Alzheimer's disease in rats with metabolic syndrome: Role of hippocampal klotho and AKT signaling pathways

Growing evidences suggest the presence of several similarities in the molecular mechanisms underlying the neurodegenerative diseases and metabolic abnormalities. Adults who develop Metabolic Syndrome (MS) are at a higher risk of developing Alzheimer's disease (AD). Pharmacological agents, like dipeptidyl peptidase-4 (DPP-4) inhibitors that increase the levels of glucagon like peptide 1 (GLP-1) and ameliorate symptoms of MS, have become an auspicious candidate as disease modifying agents in the treatment of AD. The present study investigates the beneficial effects of Vildagliptin, a DPP-4 inhibitor in counteracting cognitive decline in different models of dementia targeting the AKT, JAK/STAT signaling pathways and hippocampal Klotho expression, to judge the neuroprotective, anti-apoptotic and anti-inflammatory effects of the drug. Cognitive decline was induced by either administration of high fat high sugar (HFHS) diet for 45 days alone, or with oral administration of AlCl₃ (100 mg/kg/day) for 60 days. Rats were orally administered Vildagliptin (10 mg/kg) for 60 days along with AlCl₃ administration. Vildagliptin treatment improved spatial memory and activities in morris water maze (MWM) test and open field test respectively. Results revealed an increase of both hippocampal klotho and Bcl-2 expressions along with an increase in both AKT and ERK1/2 phosphorylation. In contrast, Vildagliptin treatment decreased hippocampal contents of inflammatory, apoptotic and oxidative stress biomarkers as TNF-α, caspase-3 and FOXO1 along with restoring metabolic abnormalities. A significant decrease in BAX expressions with JAK2/STAT3 inhibition was observed. These findings demonstrate that the neuroprotective role of vildagliptin is possibly via modulating Klotho protein together with AKT pathway.

Metabolic profiling of ligustilide and identification of the metabolite in rat and human hepatocytes by liquid chromatography combined with high-resolution mass spectrometry

Ligustilide is one of the most abundant bioactive ingredients in Rhizoma Chuanxiong that has been widely prescribed for medicinal purposes in China. To better understand the disposition and action of ligustilide, it is necessary to investigate the metabolic profiles. The in vitro metabolism was elucidated through incubating ligustilide with human and rat hepatocytes at 37°C. The incubation samples were collected at predefined time points to determine the metabolic stability. Upon metabolite identification and profiling, the incubation samples were analyzed by ultra-high-performance liquid chromatography combined with diode array detector and high-resolution mass spectrometry. The structures of the metabolites were characterized based on their mass spectrometry spectra, tandem mass spectrometry spectra, and fragmentation patterns. Ligustilide showed fast metabolism with high intrinsic clearance both in rat and human hepatocyte incubations. The half-lives of ligustilide in rat and human hepatocyte incubations were 8.0 and 15.0 min, respectively. Most of the parent (>90%) was biotransformed into the metabolites. Among these metabolites, M1 (senkyunolide I) was the major metabolite both in rat and human hepatocytes with the percentage of 42 and 70%, respectively. The metabolic pathways of ligustilide included epoxidation, epoxide hydrolysis, aromatization, hydroxylation, and glutathionylation. This work provided an overview of the metabolic profiles of ligustilide, which would be helpful for us to understand the action of this compound.

Role of Forkhead Transcription Factors of the O Class (FoxO) in Development and Progression of Alzheimer's Disease

In the Central Nervous System (CNS), a specific loss of focal neurons leads to mental and neurological disorders like dementia, Alzheimer's Disease (AD), Huntington's disease, Parkinson's disease, etc. AD is a neurological degenerative disorder, which is progressive and irreversible in nature and is the widely recognized reason for dementia in the geriatric populace. It affects 10% of people above the age of 65 and is the fourth driving reason for death in the United States. Numerous evidence suggests that the neuronal compartment is not the only genesis of AD, but transcription factors also hold significant importance in the occurrence and advancement of the disease. It is the need of the time to find the novel molecular targets and new techniques for treating or slowing down the progression of neurological disorders, especially AD. In this article, we summarised a conceivable association between transcriptional factors and their defensive measures against neurodegeneration and AD. The mammalian forkhead transcription factors of the class O (FoxO) illustrate one of the potential objectives for the development of new methodologies against AD and other neurocognitive disorders. The presence of FoxO is easily noticeable in the "cognitive centers" of the brain, specifically in the amygdala, hippocampus, and the nucleus accumbens. FoxO proteins are the prominent and necessary factors in memory formation and cognitive functions. FoxO also assumes a pertinent role in the protection of multiple cells in the brain by controlling the involving mechanism of autophagy and apoptosis and also modulates the process of phosphorylation of the targeted protein, thus FoxO must be a putative target in the mitigation of AD. This review features the role of FoxO as an important biomarker and potential new targets for the treatment of AD.

Integrated biomarker parameters response to the toxic effects of high stocking density, CuSO4, and trichlorfon on fish and protective role mediated by Angelica sinensis extract

The present study explored the protective role of dietary the extract of Angelica sinensis (EAs) on high density, CuSO₄, or trichlorfon-treated Crucian carp (Carassius auratus auratus). Firstly, the study showed that the optimum density for growth and growth inhibition was 0.49 and 0.98 fish L^-1 water, respectively. Dietary EAs relieved the high density-induced growth inhibition in Crucian carp. The appropriate concentration of EAs for recovery of growth was estimated to be 4.30 g kg^-1 diet in high-density fish. Moreover, high density decreased both digestive and absorptive enzyme activities and increased lipid oxidation in digestive organs, suggesting the ability of high density to induce oxidative damage. However, dietary EAs inhibited the oxidative damage through elevating ROS scavenging ability and enzymatic antioxidant activity in digestive organs. Secondly, our data demonstrated that the appropriate concentration of CuSO₄ to induce the decrease in feed intake (FI) was 0.8 mg Cu L^-1 water. Dietary EAs returned to FI of Crucian carp treated with CuSO₄. The appropriate concentration of EAs for recovery of FI was estimated to be 4.25 g kg^-1 diet. Moreover, dietary EAs suppressed the CuSO₄-induced decrease in digestion and absorption capacity and increase in protein metabolism in digestive organs of Crucian carp. Finally, the present results suggested that dietary EAs inhibited the trichlorfon-induced rollover (loss of equilibrium) in Crucian carp. The appropriate concentration of EAs for inhibition of rollover was estimated to be 4.18 g kg^-1 diet. Moreover, trichlorfon stimulated not only the decrease in energy metabolism but also lipid and protein oxidation, suggesting that trichlorfon caused loss of function and oxidative damage in muscles of fish. However, dietary EAs improved muscular function and inhibited oxidative damage via quenching ROS and elevating non-enzymatic and enzymatic antioxidant activity in muscles of trichlorfon-induced fish. So, EAs could be used as an inhibitor of high density, CuSO₄, and trichlorfon stress in fish.

Association between chronic kidney disease and Alzheimer's disease: an update

It has been accepted that kidney function is connected with brain activity. In clinical studies, chronic kidney disease (CKD) patients have been found to be prone to suffering cognitive decline and Alzheimer's disease (AD). The cognitive function of CKD patients may improve after kidney transplantation. All these indicators show a possible link between kidney function and dementia. However, little is known about the mechanism behind the relation of CKD and AD. This review discusses the associations between CKD and AD from the perspective of the pathophysiology of the kidney and complications and/or concomitants of CKD that may lead to cognitive decline in the progression of CKD and AD. Potential preventive and therapeutic strategies for AD are also presented. Further studies are warranted in order to confirm whether the setting of CKD is a possible new determinant for cognitive impairment in AD.

Phthalide derivative CD21 ameliorates ischemic brain injury in a mouse model of global cerebral ischemia: involvement of inhibition of NLRP3

The activation of NLRP3 inflammasome is closely related to ischemic brain injury and inhibition of NLRP3 inflammasome activation may be a new therapeutic strategy for ischemic stroke. Our previous studies showed that ligustilide (LIG) had a dose-dependent neuroprotective effect on various models of cerebral ischemia and dementia in vivo and in vitro. CD21, a kind of phthalide derivative, was modified from LIG. In this study, we established a global cerebral ischemia-reperfusion model in mice by bilateral common carotid artery ligation (2VO), and explored the neuroprotective effect of CD21 and its anti-inflammatory mechanism on cerebral ischemia mice. CD21 significantly improved weight loss, neurobehavioral deficits and neurons loss in hippocampal CA1 and caudate putamen (CPu) subregions, which were induced by 2VO in mice. CD21 significantly inhibited the overactivation of astrocyte and microglia, and decreased the mRNA level of IL-6, TNF-α and IL-1β. Moreover, CD21 significantly inhibited the activation of TLR4/NF-κB signaling pathway mediated by HMGB1 and NLRP3/ASC/Caspase-1 signaling pathway mediated by Cathepsin B, thus inhibiting the activation of NLRP3 inflammasome. Our results demonstrated that CD21 may exert a neuroprotection by inhibiting NLRP3 inflammasome activation after cerebral ischemia. These findings provide a new strategy for the treatment of ischemic stroke.

Dendrobium nobile Lindl alkaloid and metformin ameliorate cognitive dysfunction in senescence-accelerated mice via suppression of endoplasmic reticulum stress

The senescence-accelerated mouse prone 8 (SAMP8) mice have many pathological features of Alzheimer's disease (AD) with aging. We previously reported that Dendrobium nobile Lindl alkaloid (DNLA) effectively improved cognitive deficits in multiple Alzheimer's disease (AD) models. This study further used SAMP8 mice to study the anti-aging effects of DNLA, focusing on endoplasmic reticulum (ER) stress. DNLA and metformin were orally administered to SAMP8 mice starting at 4-month of age for 6 months. Behavioral tests were performed in 10-month-old SAMP8 mice and age-matched SAMR1 control mice. At the end of experiment, neuron damage was evaluated by histology and transmission electron microscopy. ER stress-related proteins were analyzed with Western-blot. DNLA improved learning and memory impairments, reduced the loss of neurons and Nissl bodies in the hippocampus and cortex. DNLA ameliorated ER dilation and swelling in the hippocampal neurons. DNLA down-regulated the protein kinase RNA-like endoplasmic reticulum kinase (PERK) signaling pathway, decreased calpain 1, GSK-3β and Cdk5 activities and the Tau hyper-phosphorylation. The effects of DNLA were comparable to metformin. In summary, DNLA was effective in improving cognitive deficits in aged SAMP8 mice, possibly via suppression of ER stress-related PERK signaling pathway, sequential inhibition of calpain 1, GSK-3β and Cdk5 activities, and eventually reducing the hyper-phosphorylation of Tau.

The Association Between Circulating Klotho and Dipeptidyl Peptidase-4 Activity and Inflammatory Cytokines in Elderly Patients With Alzheimer Disease

Introduction:

Klotho and Dipeptidyl Peptidase-4 (DPP4) are two proteins that modulate inflammatory pathways. We investigated the association between circulating klotho and DPP4 activity and their relationship with inflammatory cytokines, miR-29a, and miR-195 in Alzheimer Disease (AD).

Methods:

This study was conducted on 16 AD patients and 16 healthy age-matched controls. Plasma levels of tumor necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β, interleukin-6 (IL-6), klotho, and DPP4 were measured by enzyme-linked immunosorbent assay. Plasma expression of miR-29a and miR-195 were also measured and compared by a real-time polymerase chain reaction.

Results:

There was a significant increase in TNF-α (p=0.006), IL-1β (p=0.012), and IL-6 (p=0.012) levels in the AD subjects compared with controls. Also, we found a decrease in plasma levels of klotho and an increase in plasma levels of DPP4 in the AD group that was not significant compared with the controls. Lower expression of miR-29a (P=0.009) and higher expression of miR-195 (P=0.003) were observed in the AD group that was significant than controls. Further analysis showed a negative correlation between klotho and plasma levels of IL-6 (r=−0.58, p=0.01). Also, there was a positive correlation between plasma DPP4 activity and TNF-α levels (r=0.50, P=0.04) and IL-1β (r=0.62, P=0.01). Likewise, plasma klotho concentration showed a negative correlation with the age of AD subjects (r=−0.56, P=0.02).

Conclusion:

TNF-α, IL-1β, and IL-6 are involved in AD pathophysiology, and dysregulation of DPP4 and klotho may be associated with the inflammatory response of AD. Down-regulation of miR-29a and up-regulation of miR-195 indicated the role of miRNAs in the AD process.

Neuroprotective Effect of Phthalide Derivative CD21 against Ischemic Brain Injury:Involvement of MSR1 Mediated DAMP peroxiredoxin1 Clearance and TLR4 Signaling Inhibition

The macrophage scavenger receptor 1 (MSR1)-induced resolution of neuroinflammation may be a novel therapeutic strategy for ischemic stroke. Our previous study showed that the neuroprotective and anti-inflammatory effects of phthalide are associated with the inhibition of the post-ischemic damage-associated molecular pattern (DAMP)/Toll-like receptor 4 (TLR4) pathway. This study investigated the effects of the phthalide derivative CD21 on ischemic brain injury and the mechanism underlying MSR1-induced resolution of neuroinflammation. Using a rat model of 2 h transient middle cerebral artery occlusion (MCAO), MSR1-induced peroxiredoxin1 (PRX1) clearance in RAW264.7 macrophages were investigated. We show here that CD21 significantly ameliorated infarct volumes and neurological deficits in a dose-dependent manner with a ≥ 12 h therapeutic time window. Moreover, administration of 5 mg/kg/day CD21 over 24 h significantly reduced pathological damages, with associated inhibition of PRX1 expression, reduced TLR4/nuclear factor-κB activation and the suppression of the inflammatory response in MCAO rats. Furthermore, the expression of MAFB/MSR1 in the ischemic brain was elevated and the phagocytosis of PRX1 in CD68-positive macrophages isolated from the ischemic brain was enhanced. Further in vitro studies show that CD21 (20 μM) strongly enhanced the Msr1 mRNA and MSR1 protein levers in RAW264.7 cells and PRX1 internalization in cellular lysosomes, which were significantly reversed by N-acetylcysteine treatment. These results suggest that CD21 may exert neuroprotective and anti-inflammatory effects with a wide time window for the treatment of ischemic stroke. The anti-stroke effects of CD21 appear to be mediated partially via the induction of MSR1-promoted DAMP (PRX1) clearance, TLR4/nuclear factor-κB pathway inhibition, and the resolution of inflammation. Graphical Abstract The neuroprotective action of CD21 was associated with the resolution of neuroinflammation through enhancement of the MAFB-MSR1 pathway that leads to DAMP (PRX1) phagocytosis and TLR4 pathway inhibition. Red solid arrows represent promotion, red dotted arrow represents the positive correlation, green arrows represent inhibition.

Antiaging Factor Klotho Retards the Progress of Intervertebral Disc Degeneration through the Toll-Like Receptor 4-NF-κB Pathway

Antiaging protein Klotho exhibits impressive properties of anti-inflammation, however is declined early after intervertebral disc injury, making Klotho restoration an attractive strategy of treating intervertebral disc inflammatory disorders. Here, we have found that Klotho is enriched in nucleus pulposus (NP) cells and Klotho overexpression attenuates H₂O₂-induced acute inflammation essentially via suppressing Toll-like receptor 4 (TLR4). The proinflammatory NF-κB signaling and cytokine expressions paralleled with Klotho repression and TLR4 elevation in both NP cells (H₂O₂ treatment) and rat intervertebral disc (needle puncture treatment). Overexpression of TLR4 downregulated expression of Klotho, whereas interfering TLR4 expression diminished the inhibitory effects of H₂O₂ on Klotho in NP cells. Consistently, Klotho knockdown by RNA interferences largely diminished the anti-inflammatory and intervertebral disc protective effects in an Intervertebral Disc Degeneration (IDD) model. Thus, our study indicates that TLR4-NF-κB signaling and Klotho form a negative-feedback loop in NP cells. Also, we demonstrate that the expression of Klotho is regulated by the balance between upregulation and downregulation of TLR4-NF-κB signaling.

Probiotics modulate the microbiota-gut-brain axis and improve memory deficits in aged SAMP8 mice

ProBiotic-4 is a probiotic preparation composed of Bifidobacterium lactis, Lactobacillus casei, Bifidobacterium bifidum, and Lactobacillus acidophilus. This study aims to investigate the effects of ProBiotic-4 on the microbiota–gut–brain axis and cognitive deficits, and to explore the underlying molecular mechanism using senescence-accelerated mouse prone 8 (SAMP8) mice. ProBiotic-4 was orally administered to 9-month-old SAMP8 mice for 12 weeks. We observed that ProBiotic-4 significantly improved the memory deficits, cerebral neuronal and synaptic injuries, glial activation, and microbiota composition in the feces and brains of aged SAMP8 mice. ProBiotic-4 substantially attenuated aging-related disruption of the intestinal barrier and blood–brain barrier, decreased interleukin-6 and tumor necrosis factor-α at both mRNA and protein levels, reduced plasma and cerebral lipopolysaccharide (LPS) concentration, toll-like receptor 4 (TLR4) expression, and nuclear factor-κB (NF-κB) nuclear translocation in the brain. In addition, not only did ProBiotic-4 significantly decreased the levels of γ-H2AX, 8-hydroxydesoxyguanosine, and retinoic-acid-inducible gene-I (RIG-I), it also abrogated RIG-I multimerization in the brain. These findings suggest that targeting gut microbiota with probiotics may have a therapeutic potential for the deficits of the microbiota–gut–brain axis and cognitive function in aging, and that its mechanism is associated with inhibition of both TLR4-and RIG-I-mediated NF-κB signaling pathway and inflammatory responses.

Activity-dependent neuronal Klotho enhances astrocytic aerobic glycolysis

Mutations of the β-glucuronidase protein α-Klotho have been associated with premature aging, and altered cognitive function. Although highly expressed in specific areas of the brain, Klotho functions in the central nervous system remain unknown. Here, we show that cultured hippocampal neurons respond to insulin and glutamate stimulation by elevating Klotho protein levels. Conversely, AMPA and NMDA antagonism suppress neuronal Klotho expression. We also provide evidence that soluble Klotho enhances astrocytic aerobic glycolysis by hindering pyruvate metabolism through the mitochondria, and stimulating its processing by lactate dehydrogenase. Pharmacological inhibition of FGFR1, Erk phosphorylation, and monocarboxylic acid transporters prevents Klotho-induced lactate release from astrocytes. Taken together, these data suggest Klotho is a potential new player in the metabolic coupling between neurons and astrocytes. Neuronal glutamatergic activity and insulin modulation elicit Klotho release, which in turn stimulates astrocytic lactate formation and release. Lactate can then be used by neurons and other cells types as a metabolic substrate.