Small-molecule Klotho enhancers as novel treatment of neurodegeneration

The majority of neurodegenerative diseases have an important age component, and thus, understanding the molecular changes that occur during normal aging of the brain is of utmost relevance. In search for the basis of the age-related cognitive decline found in humans, monkeys and rodents, we study the rhesus monkey. Surprisingly, there is no loss of neurons in aged monkey brains. However, we reported white matter and myelin abnormalities in aged monkeys, similar to those observed in Alzheimer’s disease and multiple sclerosis patients. In a microarray analysis comparing young and old monkey white matter, we discovered that Klotho is downregulated in the aged brain. We then asked whether there is a connection between the age-related cognitive decline, myelin abnormalities and Klotho downregulation. If such a connection is found, compounds that upregulate Klotho expression could become of therapeutic interest for the treatment of multiple sclerosis, and perhaps even Alzheimer’s disease

PLXNA4 is associated with Alzheimer disease and modulates tau phosphorylation

OBJECTIVE: Much of the genetic basis for Alzheimer disease (AD) is unexplained. We sought to identify novel AD loci using a unique family-based approach that can detect robust associations with infrequent variants (minor allele frequency < 0.10). METHODS: We conducted a genome-wide association study in the Framingham Heart Study (discovery) and NIA-LOAD (National Institute on Aging-Late-Onset Alzheimer Disease) Study (replication) family-based cohorts using an approach that accounts for family structure and calculates a risk score for AD as the outcome. Links between the most promising gene candidate and AD pathogenesis were explored in silico as well as experimentally in cell-based models and in human brain. RESULTS: Genome-wide significant association was identified with a PLXNA4 single nucleotide polymorphism (rs277470) located in a region encoding the semaphorin-3A (SEMA3A) binding domain (meta-analysis p value [meta-P] = 4.1 × 10(-8) ). A test for association with the entire region was also significant (meta-P = 3.2 × 10(-4) ). Transfection of SH-SY5Y cells or primary rat neurons with full-length PLXNA4 (TS1) increased tau phosphorylation with stimulated by SEMA3A. The opposite effect was observed when cells were transfected with shorter isoforms (TS2 and TS3). However, transfection of any isoform into HEK293 cells stably expressing amyloid β (Aβ) precursor protein (APP) did not result in differential effects on APP processing or Aβ production. Late stage AD cases (n = 9) compared to controls (n = 5) had 1.9-fold increased expression of TS1 in cortical brain tissue (p = 1.6 × 10(-4) ). Expression of TS1 was significantly correlated with the Clinical Dementia Rating score (ρ = 0.75, p = 2.2 × 10(-4) ), plaque density (ρ = 0.56, p = 0.01), and Braak stage (ρ = 0.54, p = 0.02). INTERPRETATION: Our results indicate that PLXNA4 has a role in AD pathogenesis through isoform-specific effects on tau phosphorylation

Neurovascular Complications of Acute Aortic Syndrome

Acute aortic syndromes (AAS) such as aortic dissection, intramural hematoma, and penetrating aortic ulcer pose significant neurovascular risks, affecting patient outcomes. This review examines the incidence, clinical presentation, and outcomes of neurovascular complications in AAS patients. Common complications include stroke, spinal cord ischemia, and transient ischemic attacks, with stroke being the most prevalent. Managing aortic dissection necessitates careful blood pressure control to prevent dissection progression while avoiding compromised cerebral and spinal perfusion. Carotid involvement, particularly dissection, increases stroke and transient ischemic attack risks. Emergency surgical interventions, though essential to prevent rupture or repair dissection, carry risks of perioperative neurovascular complications. The use of electroencephalography and transcranial Doppler can aid in the early detection and monitoring of neurovascular events. We discuss the pros and cons of certain blood pressure medications in the acute treatment of aortic dissection. A multidisciplinary approach involving cardiovascular surgeons, neurologists, and critical care specialists is vital for optimizing outcomes and mitigating risks. Early recognition and management of neurovascular complications are crucial, and further research is needed to develop targeted prevention and treatment strategies

Neurovascular Complications of Acute Aortic Syndrome

Acute aortic syndromes (AAS) such as aortic dissection, intramural hematoma, and penetrating aortic ulcer pose significant neurovascular risks, affecting patient outcomes. This review examines the incidence, clinical presentation, and outcomes of neurovascular complications in AAS patients. Common complications include stroke, spinal cord ischemia, and transient ischemic attacks, with stroke being the most prevalent. Managing aortic dissection necessitates careful blood pressure control to prevent dissection progression while avoiding compromised cerebral and spinal perfusion. Carotid involvement, particularly dissection, increases stroke and transient ischemic attack risks. Emergency surgical interventions, though essential to prevent rupture or repair dissection, carry risks of perioperative neurovascular complications. The use of electroencephalography and transcranial Doppler can aid in the early detection and monitoring of neurovascular events. We discuss the pros and cons of certain blood pressure medications in the acute treatment of aortic dissection. A multidisciplinary approach involving cardiovascular surgeons, neurologists, and critical care specialists is vital for optimizing outcomes and mitigating risks. Early recognition and management of neurovascular complications are crucial, and further research is needed to develop targeted prevention and treatment strategies

Lowering of amyloid beta peptide production with a small molecule inhibitor of amyloid-? precursor protein dimerization

The amyloid ? precursor protein (APP) is a single-pass transmembrane glycoprotein that is ubiquitously expressed in many cell types, including neurons. Amyloidogenic processing of APP by ?- and ?-secretases leads to the production of amyloid-? (A?) peptides that can oligomerize and aggregate into amyloid plaques, a characteristic hallmark of Alzheimer’s disease (AD) brains. Multiple reports suggest that dimerization of APP may play a role in A? production; however, it is not yet clear whether APP dimers increase or decrease A? and the mechanism is not fully understood. To better understand the relationship between APP dimerization and production of A?, a high throughput screen for small molecule modulators of APP dimerization was conducted using APP-Firefly luciferase enzyme complementation to detect APP dimerization. Selected modulators identified from a compound library of 77,440 compounds were tested for their effects on A? generation. Two molecules that inhibited APP dimerization produced a reduction in A? levels as measured by ELISA. The inhibitors did not change sAPP? or ?-CTF levels, but lowered sAPP? levels, suggesting that blocking the dimerization is preventing the cleavage by ?-secretase in the amyloidogenic processing of APP. To our knowledge, this is the first High Throughput Screen (HTS) effort to identify small molecule modulators of APP dimerization. Inhibition of APP dimerization has previously been suggested as a therapeutic target in AD. The findings reported here further support that modulation of APP dimerization may be a viable means of reducing the production of A?

NADPH oxidases: key modulators in aging and age-related cardiovascular diseases?

Reactive oxygen species (ROS) and oxidative stress have long been linked to aging and diseases prominent in the elderly such as hypertension, atherosclerosis, diabetes and atrial fibrillation (AF). NADPH oxidases (Nox) are a major source of ROS in the vasculature and are key players in mediating redox signalling under physiological and pathophysiological conditions. In this review, we focus on the Nox-mediated ROS signalling pathways involved in the regulation of 'longevity genes' and recapitulate their role in age-associated vascular changes and in the development of age-related cardiovascular diseases (CVDs). This review is predicated on burgeoning knowledge that Nox-derived ROS propagate tightly regulated yet varied signalling pathways, which, at the cellular level, may lead to diminished repair, the aging process and predisposition to CVDs. In addition, we briefly describe emerging Nox therapies and their potential in improving the health of the elderly population

Identification of novel small molecules that elevate Klotho expression

The absence of Klotho (KL) from mice causes the development of disorders associated with human aging and decreased longevity, whereas increased expression prolongs lifespan. With age, KL protein levels decrease, and keeping levels consistent may promote healthier aging and be disease-modifying. Using the KL promoter to drive expression of luciferase, we conducted a high-throughput screen to identify compounds that activate KL transcription. Hits were identified as compounds that elevated luciferase expression at least 30%. Following validation for dose-dependent activation and lack of cytotoxicity, hit compounds were evaluated further in vitro by incubation with opossum kidney and Z310 rat choroid plexus cells, which express KL endogenously. All compounds elevated KL protein compared with control. To determine whether increased protein resulted in an in vitro functional change, we assayed FGF23 (fibroblast growth factor 23) signalling. Compounds G–I augmented ERK (extracellular-signal-regulated kinase) phosphorylation in FGFR (fibroblast growth factor receptor)-transfected cells, whereas co-transfection with KL siRNA (small interfering RNA) blocked the effect. These compounds will be useful tools to allow insight into the mechanisms of KL regulation. Further optimization will provide pharmacological tools for in vivo studies of KL

Small molecule amyloid-beta protein precursor processing modulators lower amyloid-beta peptide levels via cKit signaling

Alzheimer’s disease (AD) is characterized by the accumulation of neurotoxic amyloid-β (Aβ) peptides consisting of 39-43 amino acids, proteolytically derived fragments of the amyloid-β protein precursor (AβPP), and the accumulation of the hyperphosphorylated microtubule-associated protein tau. Inhibiting Aβ production may reduce neurodegeneration and cognitive dysfunction associated with AD. We have previously used an AβPP-firefly luciferase enzyme complementation assay to conduct a high throughput screen of a compound library for inhibitors of AβPP dimerization, and identified a compound that reduces Aβ levels. In the present study, we have identified an analog, compound Y10, which also reduced Aβ. Initial kinase profiling assays identified the receptor tyrosine kinase cKit as a putative Y10 target. To elucidate the precise mechanism involved, AβPP phosphorylation was examined by IP-western blotting. We found that Y10 inhibits cKit phosphorylation and increases AβPP phosphorylation mainly on tyrosine residue Y743, according to AβPP751 numbering. A known cKit inhibitor and siRNA specific to cKit were also found to increase AβPP phosphorylation and lower Aβ levels. We also investigated a cKit downstream signaling molecule, the Shp2 phosphatase, and found that known Shp2 inhibitors and siRNA specific to Shp2 also increase AβPP phosphorylation, suggesting that the cKit signaling pathway is also involved in AβPP phosphorylation and Aβ production. We further found that inhibitors of both cKit and Shp2 enhance AβPP surface localization. Thus, regulation of AβPP phosphorylation by small molecules should be considered as a novel therapeutic intervention for AD.This work was supported by grants from the Alzheimer's Association, the Cure Alzheimer's Fund and the Boston University Alzheimer's Disease Center. Work at the BU-CMD is supported by R24-GM111625. (Alzheimer's Association; Cure Alzheimer's Fund; R24-GM111625 - Boston University Alzheimer's Disease Center)Accepted manuscrip

Gingival crevicular fluid can degrade Emdogain and inhibit Emdogain-induced proliferation of periodontal ligament fibroblasts

Laaksonen M, Salo T, Vardar-Sengul S, Atilla G, Han Saygan B, Simmer JP, Baylas H, Sorsa T. Gingival crevicular fluid can degrade Emdogain and inhibit Emdogain-induced proliferation of periodontal ligament fibroblasts. J Periodont Res 2010; 45: 353–360. © 2009 The Authors. Journal compilation © 2009 Blackwell Munksgaard Emdogain ® (EMD), consisting mostly of amelogenin, is used in periodontal therapy to regenerate lost connective tissue. Emdogain is applied onto periodontally affected root surfaces, where it becomes exposed to proteolytic enzymes. In this study, we aimed to find out whether gingival crevicular fluid or matrix metalloproteinases (MMPs) could degrade EMD, and whether this degradation has consequences for in vitro cell proliferation . We studied the effects of 156 gingival crevicular fluid samples collected from subjects with different stages of periodontal disease and from healthy control subjects and the effects of MMP-1, -2, -8, -9, -13 and -14 on the degradation of EMD using EMD-embedded zymography. The effects of gingival crevicular fluid with or without EMD and the effects of amelogenin on the proliferation of cultured periodontal ligament fibroblasts were studied by cell proliferation enzyme-linked immunosorbent assay kit.Degradation of Emdogain induced by gingival crevicular fluid was greater in samples from all stages of periodontal diseases compared with healthy control samples. Of the MMPs studied, only MMP-2 and MMP-8 showed limited EMD-degrading activities. One hundred micrograms per millilitre of EMD increased proliferation of periodontal ligament fibroblasts on average by 24% (confidence interval 0.60–0.64) and at 200 μg/mL by 30% (confidence interval 0.62–0.68) compared with control fibroblasts (confidence interval 0.48–0.52). However, gingival crevicular fluid (10 μg/mL) together with 100 μg/mL EMD induced the proliferation only by 6% (confidence interval 0.51–0.55) and with 200 μg/mL EMD by 12% (confidence interval 0.54–0.58). Amelogenin at 200 μg/mL decreased the proliferation of periodontal ligament fibroblasts by 54% (confidence interval 0.22–0.25).We suggest that diseased gingival crevicular fluid containing various proteases leads to degradation of EMD and decreased proliferation of periodontal ligament fibroblasts.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/78583/1/j.1600-0765.2009.01244.x.pd