Changes in lipid metabolism track with the progression of neurofibrillary pathology in tauopathies.

BACKGROUND: Accumulation of tau leads to neuroinflammation and neuronal cell death in tauopathies, including Alzheimer's disease. As the disease progresses, there is a decline in brain energy metabolism. However, the role of tau protein in regulating lipid metabolism remains less characterized and poorly understood. METHODS: We used a transgenic rat model for tauopathy to reveal metabolic alterations induced by neurofibrillary pathology. Transgenic rats express a tau fragment truncated at the N- and C-terminals. For phenotypic profiling, we performed targeted metabolomic and lipidomic analysis of brain tissue, CSF, and plasma, based on the LC-MS platform. To monitor disease progression, we employed samples from transgenic and control rats aged 4, 6, 8, 10, 12, and 14 months. To study neuron-glia interplay in lipidome changes induced by pathological tau we used well well-established multicomponent cell model system. Univariate and multivariate statistical approaches were used for data evaluation. RESULTS: We showed that tau has an important role in the deregulation of lipid metabolism. In the lipidomic study, pathological tau was associated with higher production of lipids participating in protein fibrillization, membrane reorganization, and inflammation. Interestingly, significant changes have been found in the early stages of tauopathy before the formation of high-molecular-weight tau aggregates and neurofibrillary pathology. Increased secretion of pathological tau protein in vivo and in vitro induced upregulated production of phospholipids and sphingolipids and accumulation of lipid droplets in microglia. We also found that this process depended on the amount of extracellular tau. During the later stages of tauopathy, we found a connection between the transition of tau into an insoluble fraction and changes in brain metabolism. CONCLUSION: Our results revealed that lipid metabolism is significantly affected during different stages of tau pathology. Thus, our results demonstrate that the dysregulation of lipid composition by pathological tau disrupts the microenvironment, further contributing to the propagation of pathology.

CHORDC1, the novel interacting partner of tau protein.

Alzheimer's disease is currently not curable. Almost all attempts to identify disease-modifying drugs failed and the causes of disease etiology are not well understood. Neurofibrillary tangles composed of pathological tau protein belong to the main hallmarks of this disease. Identification of novel physiological and pathological tau interacting proteins may lead to a better understanding of Alzheimer's disease pathology and tau physiology and therefore we performed a screening of the brain library by a yeast two-hybrid system intending to identify new tau interaction partners. We identified CHORDC1 (cysteine and histidine-rich domain-containing protein 1) as a novel tau interaction partner by this approach. The CHORDC1-tau interaction was validated by co-immunoprecipitation from rat brain tissues and by in vitro co-localization in the cellular model expressing full-length human tau protein. We believe that our results can be useful for researchers studying tau protein in health and disease.

Annual Plasma Neurofilament Dynamics Is a Sensitive Biomarker of Disease Activity in Patients with Multiple Sclerosis.

Background and Objectives: Neurofilament light chain (NfL) is a sensitive biomarker of neuroaxonal damage. This study aimed to assess the relationship between the annual change in plasma NfL (pNfL) and disease activity in the past year, as defined by the concept no evidence of disease activity (NEDA) in a cohort of multiple sclerosis (MS) patients. Materials and Methods: Levels of pNfL (SIMOA) were examined in 141 MS patients and analyzed in relationship to the NEDA-3 status (absence of relapse, disability worsening, and MRI activity) and NEDA-4 (NEDA-3 extended by brain volume loss ≤ 0.4%) during the last 12 months. Patients were divided into two groups: annual pNfL change with an increase of less than 10% (group 1), and pNfL increases of more than 10% (group 2). Results: The mean age of the study participants (n = 141, 61% females) was 42.33 years (SD, 10.17), and the median disability score was 4.0 (3.5-5.0). The ROC analysis showed that a pNfL annual change ≥ 10% correlates with the absence of the NEDA-3 status (p < 0.001; AUC: 0.92), and the absence of the NEDA-4 status (p < 0.001; AUC: 0.839). Conclusions: Annual plasma NfL increases of more than 10% appear to be a useful tool for assessing disease activity in treated MS patients.

Neurofilament Light Chain Levels Are Associated with Disease Activity Determined by No Evident Disease Activity in Multiple Sclerosis Patients.

INTRODUCTION: There is a need for blood biomarkers of disease activity in multiple sclerosis (MS). The aim of the study was to assess the relationship between plasma neurofilament light chain (pNfL) and disease activity as defined by the concept three-domain no evident disease activity (NEDA-3). METHODS: Levels of pNfL (SIMOA) were examined in 159 MS patients and analyzed in relationship to NEDA-3 status (absence of relapse, disability score worsening, and brain magnetic resonance activity) during the last 12 months. The accuracy of the proposed model was evaluated by calculating the area under the receiver operating characteristics (ROC) curve. From the pNfL cutoff, we evaluated the NEDA-NfL status (no relapse, no Expanded Disability Status Scale [EDSS] worsening, and pNfL below the cutoff value). RESULTS: Levels of pNfL were significantly higher in MS patients than in healthy controls (p <  0.001). From a total of 159 patients, 80 (50.3%) achieved NEDA-3 status, while 79 (49.7%) patients showed evident disease activity (EDA) status. pNfL were significantly lower in the NEDA-3 group than in the EDA group (pNfL mean 7.06 pg/mL [standard deviation (SD) 2.37] vs. pNfL mean 13.04 pg/mL [SD 7.07]) (p < 0.001). ROC analysis showed that pNfL predicts NEDA-3 status (sensitivity and specificity were 80.5 and 72.7%, respectively, p < 0.001), and NEDA-NfL predicts NEDA-3 status (sensitivity and specificity were 97.1 and 82.9%, respectively, p < 0.001). CONCLUSION: The results show that pNfL levels are a useful biomarker of disease activity determined by NEDA status in patients with MS and could be an alternative to brain magnetic resonance investigation.

Technologies for the identification and validation of protein-protein interactions.

Proteins are large molecules that play essential roles in all living organisms. In most molecular processes in each cell, proteins usually do not function alone but through physiological interactions with various ligands. The most common interacting molecules for proteins are other proteins, and they act together by protein-protein interactions (PPIs) to create larger protein complexes. The impairment of physiological PPIs or establishing PPIs with pathological proteins often leads to the development of diseases. To bring insights on the knowledge about the physiological functions of proteins in biological processes, and to understand the development and pathogenesis of diseases, numerous qualitative and quantitative methods have been developed. In this review, we summarize the most commonly used methods for studying PPIs, and discuss their advantages and drawbacks.

Tau Protein Interaction Partners and Their Roles in Alzheimer's Disease and Other Tauopathies.

Tau protein plays a critical role in the assembly, stabilization, and modulation of microtubules, which are important for the normal function of neurons and the brain. In diseased conditions, several pathological modifications of tau protein manifest. These changes lead to tau protein aggregation and the formation of paired helical filaments (PHF) and neurofibrillary tangles (NFT), which are common hallmarks of Alzheimer's disease and other tauopathies. The accumulation of PHFs and NFTs results in impairment of physiological functions, apoptosis, and neuronal loss, which is reflected as cognitive impairment, and in the late stages of the disease, leads to death. The causes of this pathological transformation of tau protein haven't been fully understood yet. In both physiological and pathological conditions, tau interacts with several proteins which maintain their proper function or can participate in their pathological modifications. Interaction partners of tau protein and associated molecular pathways can either initiate and drive the tau pathology or can act neuroprotective, by reducing pathological tau proteins or inflammation. In this review, we focus on the tau as a multifunctional protein and its known interacting partners active in regulations of different processes and the roles of these proteins in Alzheimer's disease and tauopathies.

Physiological Tau Interactome in Brain and Its Link to Tauopathies.

Alzheimer's disease (AD) and most of the other tauopathies are incurable neurodegenerative diseases with unpleasant symptoms and consequences. The common hallmark of all of these diseases is tau pathology, but its connection with disease progress has not been completely understood so far. Therefore, uncovering novel tau-interacting partners and pathology affected molecular pathways can reveal the causes of diseases as well as potential targets for the development of AD treatment. Despite the large number of known tau-interacting partners, a limited number of studies focused on in vivo tau interactions in disease or healthy conditions are available. Here, we applied an in vivo cross-linking approach, capable of capturing weak and transient protein-protein interactions, to a unique transgenic rat model of progressive tau pathology similar to human AD. We have identified 175 potential novel and known tau-interacting proteins by MALDI-TOF mass spectrometry. Several of the most promising candidates for possible drug development were selected for validation by coimmunoprecipitation and colocalization experiments in animal and cellular models. Three proteins, Baiap2, Gpr37l1, and Nptx1, were confirmed as novel tau-interacting partners, and on the basis of their known functions and implications in neurodegenerative or psychiatric disorders, we proposed their potential role in tau pathology.

Neurofilament light and tau in serum after head-impact exposure in soccer.

Introduction: Blood-based biomarkers can provide valuable information on the effects of repetitive head impacts in sports. This study investigated if repetitive headers or accidental head impacts in soccer could cause structural brain injury, detected as an increase in serum neurofilament light (NfL) or tau.Methods: NfL and tau were measured in professional soccer players in pre-season. Then, the effect of three short-term exposures on biomarker levels was assessed: (1) high-intensity exercise, (2) repetitive headers, and (3) head impacts in a match.Results: We analyzed 354 samples and observed no effects on NfL from any of the three short-term exposures. Tau levels rose significantly from baseline to 1 h after (1) high-intensity exercise (Δ0.50 pg/mL, 95% CI 0.19-0.81, p < .01); the same was observed after (2) repetitive headers (Δ0.29 pg/mL, 95% CI 0.10-0.48, p < .01), but not after (3) accidental head-impact incidents (Δ0.36 pg/mL, 95% CI -0.02-0.74, p = .06). The highest absolute values were seen 1 h after high-intensity exercise (mean±SD, 1.92 ± 0.83 pg/mL).Conclusion: NfL and tau in serum were unaffected by head impacts in soccer. Importantly, tau levels seem to rise in response to exercise, emphasizing the need for control groups. Our findings highlight important characteristics and limitations when using these biomarkers in sports.

Novel Blood-Brain Barrier Shuttle Peptides Discovered through the Phage Display Method.

Delivery of therapeutic agents into the brain is a major challenge in central nervous system drug development. The blood-brain barrier (BBB) prevents access of biotherapeutics to their targets in the central nervous system and, therefore, prohibits the effective treatment of many neurological disorders. To find blood-brain barrier shuttle peptides that could target therapeutics to the brain, we applied a phage display technology on a primary endothelial rat cellular model. Two identified peptides from a 12 mer phage library, GLHTSATNLYLH and VAARTGEIYVPW, were selected and their permeability was validated using the in vitro BBB model. The permeability of peptides through the BBB was measured by ultra-performance liquid chromatography-tandem mass spectrometry coupled to a triple-quadrupole mass spectrometer (UHPLC-MS/MS). We showed higher permeability for both peptides compared to N-C reversed-sequence peptides through in vitro BBB: for peptide GLHTSATNLYLH 3.3 × 10-7 cm/s and for peptide VAARTGEIYVPW 1.5 × 10-6 cm/s. The results indicate that the peptides identified by the in vitro phage display technology could serve as transporters for the administration of biopharmaceuticals into the brain. Our results also demonstrated the importance of proper BBB model for the discovery of shuttle peptides through phage display libraries.

Dendritic Cells as an Alternate Approach for Treatment of Neurodegenerative Disorders.

Despite years of research, Alzheimer's disease (AD) remains incurable and thus poses a major health challenge in coming years. This neurodegenerative disease belongs to a heterogeneous group of human tauopathies, characterized by the extracellular deposition of beta amyloid-Aß and intracellular accumulation of tau protein in neuronal and glial cells, whereby tau pathology best correlates with disease progression. For decades, several disease-modifying agents were brought to clinical studies with promising efficacy in preclinical trials; however, all of the subsequent clinical trials failed. Therefore, the pursuit for therapeutic agents for the treatment of AD and other tauopathies still continue. Recent evidences show previously unidentified role of peripheral immune system in regulating the inflammatory status of the brain, mainly the dendritic cells. A decrease in functionality and count of dendritic cells has been observed in Alzheimer's disease. Here, we discuss a potential role of dendritic cell-based vaccines as therapeutic approach in ameliorating disease pathogenesis in AD and other tauopathies.

Intraneuronal accumulation of misfolded tau protein induces overexpression of Hsp27 in activated astrocytes.

Accumulation of misfolded forms of microtubule associated, neuronal protein tau causes neurofibrillary degeneration typical of Alzheimer's disease and other tauopathies. This process is accompanied by elevated cellular stress and concomitant deregulation of heat-shock proteins. We used a transgenic rat model of tauopathy to study involvement of heat shock protein 27 (Hsp27) in the process of neurofibrillary degeneration, its cell type specific expression and correlation with the amount of insoluble tau protein aggregates. The expression of Hsp27-mRNA is more than doubled and levels of Hsp27 protein tripled in aged transgenic animals with tau pathology. The data revealed a strong positive and highly significant correlation between Hsp27-mRNA and amount of sarkosyl insoluble tau. Interestingly, intracellular accumulation of insoluble misfolded tau protein in neurons was associated with overexpression of Hsp27 almost exclusively in reactive astrocytes, not in neurons. The topological dissociation of neuronally expressed pathological tau and the induction of astrocytic Hsp27, GFAP, and Vimentin along with up-regulation of microglia specific markers such as CD18, CD68 and C3 point to cooperation of astrocytes, microglia and neurons in response to intra-neuronal accumulation of insoluble tau. Our data suggest that over expression of Hsp27 represents a part of microglia-mediated astrocytic response mechanism in the process of neurofibrillary degeneration, which is not necessarily associated with neuroprotection and which in contrary may accelerate neurodegeneration in late stage of the disease. This phenomenon should be considered during development of disease modifying strategies for treatment of tauopathies and AD via regulation of activity of Hsp27.

Efficacy assessment of an active tau immunotherapy in Alzheimer's disease patients with amyloid and tau pathology: a post hoc analysis of the "ADAMANT" randomised, placebo-controlled, double-blind, multi-centre, phase 2 clinical trial.

BACKGROUND: Tau pathology correlates with and predicts clinical decline in Alzheimer's disease. Approved tau-targeted therapies are not available. METHODS: ADAMANT, a 24-month randomised, placebo-controlled, parallel-group, double-blinded, multicenter, Phase 2 clinical trial (EudraCT2015-000630-30, NCT02579252) enrolled 196 participants with Alzheimer's disease; 119 are included in this post-hoc subgroup analysis. AADvac1, active immunotherapy against pathological tau protein. A machine learning model predicted likely Amyloid+Tau+ participants from baseline MRI. STATISTICAL METHODS: MMRM for change from baseline in cognition, function, and neurodegeneration; linear regression for associations between antibody response and endpoints. RESULTS: The prediction model achieved PPV of 97.7% for amyloid, 96.2% for tau. 119 participants in the full analysis set (70 treatment and 49 placebo) were classified as A+T+. A trend for CDR-SB 104-week change (estimated marginal means [emm] = -0.99 points, 95% CI [-2.13, 0.13], p = 0.0825]) and ADCS-MCI-ADL (emm = 3.82 points, CI [-0.29, 7.92], p = 0.0679) in favour of the treatment group was seen. Reduction was seen in plasma NF-L (emm = -0.15 log pg/mL, CI [-0.27, -0.03], p = 0.0139). Higher antibody response to AADvac1 was related to slowing of decline on CDR-SB (rho = -0.10, CI [-0.21, 0.01], p = 0.0376) and ADL (rho = 0.15, CI [0.03, 0.27], p = 0.0201), and related to slower brain atrophy (rho = 0.18-0.35, p < 0.05 for temporal volume, whole cortex, and right and left hippocampus). CONCLUSIONS: In the subgroup of ML imputed or CSF identified A+T+, AADvac1 slowed AD-related decline in an antibody-dependent manner. Larger anti-tau trials are warranted. FUNDING: AXON Neuroscience SE.

Association of Nonconcussive Repetitive Head Impacts and Intense Physical Activity With Levels of Phosphorylated Tau181 and Total Tau in Plasma of Young Elite Soccer Players.

Importance: Head impacts resulting in traumatic brain injury (TBI) lead to the elevation of phosphorylated tau protein (p-tau181) in plasma. To our knowledge, this study is the first to investigate dynamics of p-tau181 levels and the ratio of p-tau181 to total tau in individuals after nonconcussive head impacts. Objective: To determine the association of repetitive low-intensity head impacts on p-tau181 and total tau protein levels in the plasma of young adult elite soccer players and assess the possible association of head impacts with focused attention and cognitive flexibility. Design, Setting, and Participants: In this cohort study, young elite soccer players performed intense physical activity with and without heading the ball. The study was conducted at a university facility in Slovakia from October 1, 2021, to May 31, 2022. Eligible participants were selected based on similarities in demographic variables, excluding those with a history of TBI. Main Outcomes and Measures: The primary study outcomes were the levels of total tau protein and p-tau181 in plasma samples and the cognitive status of the study participants. Results: A total of 37 male athletes participated in the study (mean [SD] age: exercise group, 21.6 [1.6] years; heading group, 21.2 [1.5] years). We found significantly elevated levels of total tau and p-tau181 in the plasma of soccer players 1 hour after physical exercise (tau, 1.4-fold; 95% CI, 1.2-1.5; P < .001; p-tau181, 1.4-fold; 95% CI, 1.3-1.5, P < .001) and repetitive head impacts (tau, 1.3-fold; 95% CI, 1.2-1.4; P < .001; p-tau181, 1.5-fold; 95% CI, 1.4-1.7 P < .001). The ratio of p-tau181 to tau was significantly higher 1 hour after exercise and heading training, and remained elevated specifically in the heading group even after 24 hours (1.2-fold; 95% CI, 1.1-1.3; P = .002). Performance in cognitive tests revealed a significant decline in focused attention and cognitive flexibility after physical exercise and heading training; physical exercise of higher intensity without heading training was associated with a greater negative cognitive performance than heading only. Conclusions and Relevance: In this cohort study of young elite soccer players, the elevation of p-tau181 and tau was observed after acute intense physical activity and nonconcussive repetitive head impacts. The increase of p-tau181 levels relative to tau after 24 hours indicated an acute enrichment of phosphorylated tau fraction in the periphery when compared with preimpact levels; an imbalance of tau proteins may have long-lasting consequences in the brain of head-impacted individuals.

Analog of kynurenic acid decreases tau pathology by modulating astrogliosis in rat model for tauopathy.

Kynurenines have immunomodulatory and neuroactive properties and can influence the central nervous system. Previous studies showed the involvement of the kynurenines in the pathogenesis and progression of neurodegenerative disease. In neurodegenerative disorders, including tauopathies, the tryptophan metabolism is shifted toward neurotoxic agents and the reduction of neuroprotectant products. Astrocyte-derived kynurenic acid serves as a neuroprotectant. However, systemic administration of kynurenic acid is not effective because of low permeability across the blood-brain barrier (BBB). We used a kynurenic acid analog with similar biological activity but higher brain permeability to overcome BBB limitations. In the present study, we used amide derivate of kynurenic acid N-(2-N, N-dimethylaminoethyl)- 4-oxo-1 H-quinoline-2-carboxamid (KYNA-1). We administered KYNA-1 for three months to tau transgenic rats SHR-24 and analyzed the effect on tau pathology and activation of glial cells. Primary glial cell cultures were applied to identify the mechanism of the KYNA-1 effect. KYNA-1 was not toxic to rats after chronic three-month administration. When chronically administered, KYNA-1 reduced hyperphosphorylation of insoluble tau in the brain of transgenic rats. Noteworthily, the plasma total tau was also reduced. We determined that the effect of KYNA-1 on tau pathology was induced through the modulation of glial activation. KYNA-1 inhibited LPS induced activation of astrocytes and induced transformation of microglia to M2 phenotype. We identified that the administration of KYNA-1 reduced tau hyperphosphorylation and neuroinflammation. KYNA-1 may serve as a promising treatment for tauopathies.

Associations between neurofilament light chain levels, disease activity and brain atrophy in progressive multiple sclerosis.

BACKGROUND: Neurofilament light chain is a promising biomarker of disease activity and treatment response in relapsing-remitting multiple sclerosis (MS). Its role in progressive MS is less clear. AIM: The aim of the study was to assess the relationship between plasma neurofilament light chain (pNfL) and disease activity as defined by the concept NEDA-3 (No Evident Disease Activity), and brain volumetry, in a cohort of patients with the progressive disease form (PMS). METHODS: Levels of pNfL (SIMOA technology) were examined in 52 PMS patients and analysed in relationship to NEDA-3 status and annual brain volume loss (BVL) during the last 12 months. The statistical model was developed using logistic regression analysis, including demographic, clinical and magnetic resonance imaging (MRI) data as independent variables. Dependent variables were NEDA-3 status and BVL. RESULTS: The mean age of the study participants (n=52, 50% females) was 45.85 (SD, 9.82) and the median disability score was 5.0 (IQR: 5.0-5.5). ROC analysis showed that pNfL predicts NEDA-3 (the sensitivity and specificity of the model were 77.8% and 87.6%, respectively, P<0.001) and abnormal BVL (the sensitivity and specificity were 96.6% and 68.2%, respectively, P<0.001). CONCLUSIONS: The results show that pNfL levels are a useful biomarker of disease activity determined by NEDA-3 status, including brain MRI-volumetry, in patients with the progressive form of MS.

Monoclonal antibodies targeting two immunodominant epitopes on the Spike protein neutralize emerging SARS-CoV-2 variants of concern.

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.

ADAMANT: a placebo-controlled randomized phase 2 study of AADvac1, an active immunotherapy against pathological tau in Alzheimer's disease.

Alzheimer's disease (AD) pathology is partly characterized by accumulation of aberrant forms of tau protein. Here we report the results of ADAMANT, a 24-month double-blinded, parallel-arm, randomized phase 2 multicenter placebo-controlled trial of AADvac1, an active peptide vaccine designed to target pathological tau in AD (EudraCT 2015-000630-30). Eleven doses of AADvac1 were administered to patients with mild AD dementia at 40 µg per dose over the course of the trial. The primary objective was to evaluate the safety and tolerability of long-term AADvac1 treatment. The secondary objectives were to evaluate immunogenicity and efficacy of AADvac1 treatment in slowing cognitive and functional decline. A total of 196 patients were randomized 3:2 between AADvac1 and placebo. AADvac1 was safe and well tolerated (AADvac1 n = 117, placebo n = 79; serious adverse events observed in 17.1% of AADvac1-treated individuals and 24.1% of placebo-treated individuals; adverse events observed in 84.6% of AADvac1-treated individuals and 81.0% of placebo-treated individuals). The vaccine induced high levels of IgG antibodies. No significant effects were found in cognitive and functional tests on the whole study sample (Clinical Dementia Rating-Sum of the Boxes scale adjusted mean point difference -0.360 (95% CI -1.306, 0.589)), custom cognitive battery adjusted mean z-score difference of 0.0008 (95% CI -0.169, 0.172). We also present results from exploratory and post hoc analyses looking at relevant biomarkers and clinical outcomes in specific subgroups. Our results show that AADvac1 is safe and immunogenic, but larger stratified studies are needed to better evaluate its potential clinical efficacy and impact on disease biomarkers.

Brain Drug Delivery: Overcoming the Blood-brain Barrier to Treat Tauopathies.

Tauopathies are neurodegenerative disorders characterized by the deposition of abnormal tau protein in the brain. The application of potentially effective therapeutics for their successful treatment is hampered by the presence of a naturally occurring brain protection layer called the blood-brain barrier (BBB). BBB represents one of the biggest challenges in the development of therapeutics for central nervous system (CNS) disorders, where sufficient BBB penetration is inevitable. BBB is a heavily restricting barrier regulating the movement of molecules, ions, and cells between the blood and the CNS to secure proper neuronal function and protect the CNS from dangerous substances and processes. Yet, these natural functions possessed by BBB represent a great hurdle for brain drug delivery. This review is concentrated on summarizing the available methods and approaches for effective therapeutics' delivery through the BBB to treat neurodegenerative disorders with a focus on tauopathies. It describes the traditional approaches but also new nanotechnology strategies emerging with advanced medical techniques. Their limitations and benefits are discussed.

Novel Diagnostic Tools for Identifying Cognitive Impairment in Dogs: Behavior, Biomarkers, and Pathology.

Canine cognitive dysfunction syndrome (CCDS) is a progressive neurodegenerative disorder in senior dogs that is mainly associated with decreased ability to learn and respond to stimuli. It is commonly under-diagnosed because behavioral changes are often attributed to the natural process of aging. In the present study, we used for the first time a comprehensive approach enabling early diagnosis of canine patients with mild cognitive disorders (MiCI). We included CAnine DEmentia Scale (CADES) questionnaires, biochemical parameters, and biomarkers in blood serum, and correlated them with post-mortem histopathological changes. The CADES questionnaires enabled us to identify MiCI dogs developing changes mainly in domains corresponding to social interaction and spatial orientation, which seems to be crucial for delineating early cognitive disorders. Biochemical analyses in these dogs showed slightly elevated liver enzyme parameters (AST and ALT) and significantly decreased sodium and chloride levels in blood serum. Furthermore, we describe for the first time a significant increase of neurofilament light chain (NFL) in blood serum of MiCI dogs, compared to normal aging seniors and young controls, but no changes in TAU protein and amyloid-ß (Aß42) peptide levels. In canine brains with cognitive impairment, amyloid plaques of mainly diffuse and dense types were detected. Furthermore, activated microglia with amoeboid body and dystrophic processes occurred, in some cases with spheroidal and bulbous swellings. On the other hand, no TAU pathology or neurofibrillary tangles were detected. These results suggest that a combination of CADES questionnaire mainly with CNS injury biomarker (NFL) and with biochemical parameters (ALT, AST, Na, and Cl) in blood serum may predict CCDS in senior dogs.

Neurofilament light chain and MRI volume parameters as markers of neurodegeneration in multiple sclerosis.

BACKGROUND: Neurofilament light chain (NfL) is considered a major marker of neurodegeneration and disease activity. Higher levels of NfL are associated with worse clinical outcomes and increased brain atrophy. In treated patients with Relapsing-Remitting Multiple Sclerosis (RRMS), we aimed to determine the level of NfL, an association between NfL and demographic, clinical and magnetic resonance imaging (MRI) characteristics as well as brain volume parameters. We wanted to confirm that level of NfL is clinically useful as biomarker of neurodegeneration and disease activity. METHODS: 56 treated RRMS patients were enrolled. Plasmatic levels of NfL (pNfL) were measured by SIMOA® technique. Clinical severity of MS was expressed by Expanded Disability Status Scale (EDSS), and volumetric analysis of MRI data was performed using Icobrain software. RESULTS: The mean pNfL level was significantly higher in MS patients than in healthy controls (14.73 ± 6.38 versus 6.67 ± 3.9, p<0.001). In patients, we did not find association between pNfL and MRI activity, number of new T2 lesions, and number of enhancing lesions. Levels of pNfL correlated significantly with atrophy of whole brain volume (Wbv), atrophy of grey matter volume (Gmv), and negatively with Wbv. We found significantly positive correlation between pNfL levels and EDSS. CONCLUSION: Study shows association of pNfL with Wbv, presence of brain atrophy and EDSS, and strong correlation of EDSS with multiple MRI volume parameters. We did not confirm association pNfL with disease activity. Our data suggest that pNfL and MRI volume parameters could be considered as biomarkers of neurodegeneration in MS.