Extracellular matrix (ECM) is a network of macromolecules which has two forms-perineuronal nets (PNNs) and a diffuse ECM (dECM)-both influence brain development, synapse formation, neuroplasticity, CNS injury and progression of neurodegenerative diseases. ECM remodeling can influence extrasynaptic transmission, mediated by diffusion of neuroactive substances in the extracellular space (ECS). In this study we analyzed how disrupted PNNs and dECM influence brain diffusibility. Two months after oral treatment of rats with 4-methylumbelliferone (4-MU), an inhibitor of hyaluronan (HA) synthesis, we found downregulated staining for PNNs, HA, chondroitin sulfate proteoglycans, and glial fibrillary acidic protein. These changes were enhanced after 4 and 6 months and were reversible after a normal diet. Morphometric analysis further indicated atrophy of astrocytes. Using real-time iontophoretic method dysregulation of ECM resulted in increased ECS volume fraction α in the somatosensory cortex by 35%, from α = 0.20 in control rats to α = 0.27 after the 4-MU diet. Diffusion-weighted magnetic resonance imaging revealed a decrease of mean diffusivity and fractional anisotropy (FA) in the cortex, hippocampus, thalamus, pallidum, and spinal cord. This study shows the increase in ECS volume, a loss of FA, and changes in astrocytes due to modulation of PNNs and dECM that could affect extrasynaptic transmission, cell-to-cell communication, and neural plasticity.

• Klíčová slova
• extracellular diffusion, extracellular matrix, extracellular transmission, hyaluronan synthase, perineuronal nets, plasticity,
• MeSH
• astrocyty metabolismus   MeSH
• chondroitinsulfát proteoglykany metabolismus   MeSH
• extracelulární matrix * metabolismus   MeSH
• extracelulární prostor * metabolismus   MeSH
• gliový fibrilární kyselý protein metabolismus   MeSH
• hymekromon farmakologie   MeSH
• krysa rodu Rattus MeSH
• kyselina hyaluronová MeSH
• mozek metabolismus   MeSH
• nervová síť účinky léků   diagnostické zobrazování   MeSH
• potkani Sprague-Dawley MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• chondroitinsulfát proteoglykany MeSH
• gliový fibrilární kyselý protein MeSH
• hymekromon MeSH
• kyselina hyaluronová MeSH

INTRODUCTION: Alzheimer's disease (AD) is marked by the accumulation of fibrillary aggregates composed of pathological tau protein. Although neuroinflammation is frequently observed in conjunction with tau pathology, current preclinical evidence does not sufficiently establish a direct causal role in tau tangle formation. This study aimed to evaluate whether chronic Toll-like receptor 4 (TLR4) stimulation, induced by a high dose of lipopolysaccharide (LPS, 5 mg/kg), exacerbates neurofibrillary tangle (NFT) pathology in a transgenic mouse model of tauopathy that expresses human truncated 151-391/3R tau, an early feature of sporadic AD. METHODS: We utilized a transgenic mouse model of tauopathy subjected to chronic TLR4 stimulation via weekly intraperitoneal injections of LPS over nine consecutive weeks. Neurofibrillary tangle formation, microglial activation, and tau hyperphosphorylation in the brainstem and hippocampus were assessed through immunohistochemistry, immunofluorescence, and detailed morphometric analysis of microglia. RESULTS: Chronic LPS treatment led to a significant increase in the number of Iba-1+ microglia in the LPS-treated group compared to the sham group (p < 0.0001). Notably, there was a 1.5- to 1.7-fold increase in microglia per tangle-bearing neuron in the LPS-treated group. These microglia exhibited a reactive yet exhausted phenotype, characterized by a significant reduction in cell area (p < 0.0001) without significant changes in other morphometric parameters, such as perimeter, circumference, solidity, aspect ratio, or arborization degree. Despite extensive microglial activation, there was no observed reduction in tau hyperphosphorylation or a decrease in tangle formation in the brainstem, where pathology predominantly develops in this model. DISCUSSION: These findings suggest that chronic TLR4 stimulation in tau-transgenic mice results in significant microglial activation but does not influence tau tangle formation. This underscores the complexity of the relationship between neuroinflammation and tau pathology, indicating that additional mechanisms may be required for neuroinflammation to directly contribute to tau tangle formation.

• Klíčová slova
• lipopolysaccharide, microglia, neuroinflammation, phosphorylation, tau,
• Publikační typ
• časopisecké články MeSH

The transcellular propagation of the aberrantly modified protein tau along the functional brain network is a key hallmark of Alzheimer's disease and related tauopathies. Inoculation-based tau propagation models can recapitulate the stereotypical spread of tau and reproduce various types of tau inclusions linked to specific tauopathy, albeit with varying degrees of fidelity. With this systematic review, we underscore the significance of judicious selection and meticulous functional, biochemical, and biophysical characterization of various tau inocula. Furthermore, we highlight the necessity of choosing suitable animal models and inoculation sites, along with the critical need for validation of fibrillary pathology using confirmatory staining, to accurately recapitulate disease-specific inclusions. As a practical guide, we put forth a framework for establishing a benchmark of inoculation-based tau propagation models that holds promise for use in preclinical testing of disease-modifying drugs.

• Klíčová slova
• Aggregation, Animal models, Neurofibrillary tangles, Propagation, Spreading, Tau protein,
• MeSH
• Alzheimerova nemoc * patologie   MeSH
• modely nemocí na zvířatech MeSH
• mozek patologie   MeSH
• neurofibrilární klubka patologie   MeSH
• proteiny tau metabolismus   MeSH
• tauopatie * patologie   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH
• systematický přehled MeSH
• Názvy látek
• proteiny tau MeSH

INTRODUCTION: The typical symptoms of Alzheimer's disease (AD) are cognitive impairment, disrupted spatial orientation, behavioral and psychiatric abnormalities, and later motor deficits. Neuropathologically, AD is characterized by deposits of pathological forms of endogenous proteins - amyloid-β, and neurofibrillary tau protein pathology. The latter closely correlates with brain atrophy and clinical impairment. Pharmacological therapies for these pathologies are largely absent, raising the question whether non-pharmacological interventions could be efficacious. Environmental factors can play a role in the manifestation of AD. It is unknown whether enriched environment (EE) can ameliorate the propagation of protein aggregates or their toxic components. METHODS: We injected insoluble tau extracts from human brains with AD (600 or 900 ng per animal) into hippocampi of SHR72 transgenic rats that express non-mutated truncated human tau 151-391/4R, but usually do not develop hippocampal tangles. The rats had either standard housing, or could access an EE 5×/week for 3 months. Behavioral analysis included the Morris Water Maze (MWM). Histological analysis was used to assess the propagation of tau pathology. RESULTS: Animals exposed to EE performed better in the MWM (spatial acquisition duration and total distance, probe test); unexposed animals improved over the course of acquisition trials, but their mean performance remained below that of the EE group. Enriched environment abrogated tau propagation and hippocampal tangle formation in the 600 ng group; in the 900 ng group, tangle formation was ∼10-fold of the 600 ng group, and unaffected by EE. CONCLUSION: Even a small difference in the amount of injected human AD tau can cause a pronounced difference in the number of resulting tangles. EE leads to a noticeably better spatial navigation performance of tau-injected animals. Furthermore, EE seems to be able to slow down tau pathology progression, indicating the possible utility of similar interventions in early stages of AD where tangle loads are still low.

• Klíčová slova
• behavioral, enriched environment, histology, propagation, seeding, tangle, tau,
• Publikační typ
• časopisecké články MeSH

BACKGROUND: The emergence of new SARS-CoV-2 variants of concern B.1.1.7 (Alpha), B.1.351 (Beta), P.1 (Gamma) and B.1.617.2 (Delta) that harbor mutations in the viral S protein raised concern about activity of current vaccines and therapeutic antibodies. Independent studies have shown that mutant variants are partially or completely resistant against some of the therapeutic antibodies authorized for emergency use. METHODS: We employed hybridoma technology, ELISA-based and cell-based S-ACE2 interaction assays combined with authentic virus neutralization assays to develop second-generation antibodies, which were specifically selected for their ability to neutralize the new variants of SARS-CoV-2. FINDINGS: AX290 and AX677, two monoclonal antibodies with non-overlapping epitopes, exhibit subnanomolar or nanomolar affinities to the receptor binding domain of the viral Spike protein carrying amino acid substitutions N501Y, N439K, E484K, K417N, and a combination N501Y/E484K/K417N found in the circulating virus variants. The antibodies showed excellent neutralization of an authentic SARS-CoV-2 virus representing strains circulating in Europe in spring 2020 and also the variants of concern B.1.1.7 (Alpha), B.1.351 (Beta) and B.1.617.2 (Delta). In addition, AX677 is able to bind Omicron Spike protein just like the wild type Spike. The combination of the two antibodies prevented the appearance of escape mutations of the authentic SARS-CoV-2 virus. Prophylactic administration of AX290 and AX677, either individually or in combination, effectively reduced viral burden and inflammation in the lungs, and prevented disease in a mouse model of SARS-CoV-2 infection. INTERPRETATION: The virus-neutralizing properties were fully reproduced in chimeric mouse-human versions of the antibodies, which may represent a promising tool for COVID-19 therapy. FUNDING: The study was funded by AXON Neuroscience SE and AXON COVIDAX a.s.

• Klíčová slova
• COVID-19, Escape mutation, Neutralizing antibodies, SARS-CoV-2, Variants of concern,
• MeSH
• angiotensin-konvertující enzym 2 chemie   genetika   metabolismus   MeSH
• antigenní drift a shift MeSH
• COVID-19 virologie   MeSH
• farmakoterapie COVID-19 MeSH
• glykoprotein S, koronavirus genetika   imunologie   metabolismus   MeSH
• imunodominantní epitopy imunologie   MeSH
• kinetika MeSH
• lidé MeSH
• modely nemocí na zvířatech MeSH
• monoklonální protilátky imunologie   terapeutické užití   MeSH
• mutace MeSH
• myši MeSH
• neutralizační testy MeSH
• plíce patologie   MeSH
• protinádorové látky imunologicky aktivní imunologie   terapeutické užití   MeSH
• SARS-CoV-2 genetika   imunologie   izolace a purifikace   MeSH
• vazba proteinů MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• ACE2 protein, human MeSH Prohlížeč
• angiotensin-konvertující enzym 2 MeSH
• glykoprotein S, koronavirus MeSH
• imunodominantní epitopy MeSH
• monoklonální protilátky MeSH
• protinádorové látky imunologicky aktivní MeSH
• spike protein, SARS-CoV-2 MeSH Prohlížeč

Vertebrate primary cilium is a Hedgehog signaling center but the extent of its involvement in other signaling systems is less well understood. This report delineates a mechanism by which fibroblast growth factor (FGF) controls primary cilia. Employing proteomic approaches to characterize proteins associated with the FGF-receptor, FGFR3, we identified the serine/threonine kinase intestinal cell kinase (ICK) as an FGFR interactor. ICK is involved in ciliogenesis and participates in control of ciliary length. FGF signaling partially abolished ICK's kinase activity, through FGFR-mediated ICK phosphorylation at conserved residue Tyr15, which interfered with optimal ATP binding. Activation of the FGF signaling pathway affected both primary cilia length and function in a manner consistent with cilia effects caused by inhibition of ICK activity. Moreover, knockdown and knockout of ICK rescued the FGF-mediated effect on cilia. We provide conclusive evidence that FGF signaling controls cilia via interaction with ICK.

• Klíčová slova
• FGFR, ICK, cilia length, fibroblast growth factor, intestinal cell kinase,
• MeSH
• buňky NIH 3T3 MeSH
• cilie metabolismus   MeSH
• CRISPR-Cas systémy MeSH
• fibroblastové růstové faktory metabolismus   MeSH
• fosforylace MeSH
• HEK293 buňky MeSH
• interakční proteinové domény a motivy MeSH
• lidé MeSH
• modely u zvířat MeSH
• myši knockoutované MeSH
• myši MeSH
• protein-serin-threoninkinasy genetika   metabolismus   MeSH
• proteiny hedgehog metabolismus   MeSH
• proteomika MeSH
• receptor fibroblastových růstových faktorů, typ 1 metabolismus   MeSH
• receptor fibroblastových růstových faktorů, typ 3 genetika   metabolismus   MeSH
• receptor fibroblastových růstových faktorů, typ 4 metabolismus   MeSH
• receptory fibroblastových růstových faktorů genetika   metabolismus   MeSH
• signální transdukce MeSH
• simulace molekulového dockingu MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH
• Názvy látek
• CILK1 protein, human MeSH Prohlížeč
• Cilk1 protein, mouse MeSH Prohlížeč
• FGFR1 protein, human MeSH Prohlížeč
• FGFR3 protein, human MeSH Prohlížeč
• FGFR4 protein, human MeSH Prohlížeč
• fibroblastové růstové faktory MeSH
• protein-serin-threoninkinasy MeSH
• proteiny hedgehog MeSH
• receptor fibroblastových růstových faktorů, typ 1 MeSH
• receptor fibroblastových růstových faktorů, typ 3 MeSH
• receptor fibroblastových růstových faktorů, typ 4 MeSH
• receptory fibroblastových růstových faktorů MeSH