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Discovering novel diagnostic biomarkers and signatures for traumatic brain injury (TBI) represents a major challenge in the brain trauma research. Detailed analysis of post-concussive molecular pathways based on experimental data could provide a new insight into the pathophysiological sequelae and mapping of recovery mechanisms involved in TBI. MicroRNAs (miRNAs) detectable in peripheral body fluids after TBI are promising carriers of this missing knowledge. In order to define the signature of peripheral miRNAs signaling associated with mild TBI (mTBI), we performed a comprehensive meta-analysis of miRNA profiles in mTBI patients using multiple curated pathway databases. Using a bioinformatic pipeline with integrated data analysis we identified a set of genes that are connected to deregulated circulating miRNAs following the mTBI. Identified genes belong to specific pathways of MAPK, TGF-β, WNT, TLR2/4, PI3K/AKT, insulin, and growth factor signaling. Since the enriched pathways markedly overlap among the various biological fluids, signaling associated with mTBI that is concomitantly reflected in serum, plasma and saliva is robust and unique. Furthermore, we identified a network of 33 validated interacting proteins and their regulatory miRNAs that link the post-mTBI signaling in peripheral fluids with neurodegeneration-associated interaction pathways. Presented data provide a comprehensive insight into molecular events following mTBI, and the top predicted genes represent a group of novel candidate targets to be validated in connection with mTBI.

Traumatic brain injury in contact sports can lead to serious health consequences either immediately or later in the life of injured subjects. The objective of this study was to estimate the incidence of head impacts in the Under 18 (U18) and Under 20 (U20) junior ice-hockey leagues in Slovakia over the seasons 2013/2014-2016/2017 using data from official game statistics. Incidence risks (IR) per 1000 athlete exposures were calculated for the season and stratified by a period of the game, by month, round, and part of the season. IR of head impacts ranged from 2.09 (95%CI: 2.07-2.12) to 2.89 (95%CI: 2.87-2.92) in the U18 league and from 2.14 (95%CI: 2.12-2.17) to 4.06 (95%CI: 4.02-4.09) in the U20. Higher IR was observed in the latter periods of games. This study brings first data on the incidence of concussions in youth ice-hockey leagues in Slovakia and calls for immediate implementation of measures to prevent these injuries.

Neurodegeneration is associated with hypertension and disturbance in fat metabolism. The complex interaction of neurodegenerative processes with both metabolic changes and blood pressure is still not fully elucidated. Here we demonstrate that the experimentally induced tauopathy in hypertensive transgenic animals causes significant downregulation of plasma leptin (53% of control), reduction of body weight by 11%, a 1.2-fold drop of adiposity index, and decrease in HDL cholesterol level, while the fasting glucose and insulin concentration remain unchanged. Despite of these alterations we found the leptin projection circuit including the arcuate nucleus, paraventricular nucleus in hypothalamus, and nucleus tractus solitarius in the brainstem not affected by neurofibrillary pathology. Furthermore, hypertension does not alter disturbances in leptin signalling. The presented data provide further insight into neurodegeneration-induced metabolic alterations relevant for human tauopathies.

Spreading of tau pathology to anatomical distinct regions in Alzheimer's disease (AD) is associated with progression of the disease. Studies in recent decade have strived to understand the processes involved in this characteristic spread. We recently showed that AD-derived insoluble tau seeds are able to initiate neurofibrillary pathology in transgenic rodent model of tauopathy. In the present study, we pursued to identify the molecular changes that govern the induction and propagation of tau pathology on the transcriptomic level. We first show that microglia in vicinity to AD-Tau-induced pathology has phagocytic morphology when compared to PBS-injected group. On transcriptomic level, we observed deregulation of 15 genes 3-month post AD-Tau seeds inoculation. Integrated bioinformatic analysis identified 31 significantly enriched pathways. Amongst these, the inflammatory signalling pathway mediated by cytokine and chemokine networks, along with, toll-like receptor and JAK-STAT signalling were the most dominant. Furthermore, the enriched signalling also involved the regulation of autophagy, mitophagy and endoplasmic reticulum stress pathways. To our best of knowledge, the study is the first to investigate the transcriptomic profile of AD-Tau seed-induced pathology in hippocampus of transgenic model of tauopathy.

The close relationship between Alzheimer's disease (AD) and obesity was recognized many years ago. However, complete understanding of the pathological mechanisms underlying the interactions between degeneration of CNS and fat metabolism is still missing. The leptin a key adipokine of white adipose tissue has been suggested as one of the major mediators linking the obesity and AD. Here we investigated the association between peripheral levels of leptin, general metabolic status and stage of the pathogenesis in rat transgenic model of AD. We demonstrate significantly decreased levels of plasma leptin in animals with experimentally induced progressive neurofibrillary pathology, which represents only 62.3% (P = 0.0015) of those observed in normal wild type control animals. More detailed analysis showed a strong and statistically significant inverse correlation between the load of neurofibrillary pathology and peripheral levels of leptin (r = - 0.7248, P = 0.0177). We also observed a loss of body weight during development of neurodegeneration (about 14% less than control animals, P = 0.0004) and decrease in several metabolic parameters such as glucose, insulin, triglycerides and VLDL in plasma of the transgenic animals. Our data suggest that plasma leptin could serve as a convenient peripheral biomarker for tauopathies and Alzheimer's disease. Decrease in gene expression of leptin in fat tissue and its plasma level was found as one of the consequences of experimentally induced neurodegeneration. Our data may help to design rational diagnostic and therapeutic strategies for patients suffering from Alzheimer's disease or other forms of tauopathy.

ImportanceHead 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.ObjectiveTo 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 ParticipantsIn 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 MeasuresThe primary study outcomes were the levels of total tau protein and p-tau181 in plasma samples and the cognitive status of the study participants.ResultsA 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 181, 1.4-fold; 95% CI, 1.3-1.5, P P 181, 1.5-fold; 95% CI, 1.4-1.7 P 181 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 RelevanceIn 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.

To explore the short-term effects of accidental head impacts and repetitive headers on circulating microRNAs, accounting for the effects of high-intensity exercise alone. Blood samples were collected from professional soccer players at rest. Repeat samples were drawn 1 h and 12 h after three conditions: (1) accidental head impacts in a match, (2) repetitive headers during training, and (3) high-intensity exercise. 89 samples were screened to detect microRNAs expressed after each exposure. Identified microRNAs were then validated in 98 samples to determine consistently deregulated microRNAs. Deregulated microRNAs were further explored using bioinformatics to identify target genes and characterize their involvement in biological pathways. Accidental head impacts led to deregulation of eight microRNAs that were unaffected by high-intensity exercise; target genes were linked to 12 specific signaling pathways, primarily regulating chromatin organization, Hedgehog and Wnt signaling. Repetitive headers led to deregulation of six microRNAs that were unaffected by high-intensity exercise; target genes were linked to one specific signaling pathway (TGF-β). High-intensity exercise led to deregulation of seven microRNAs; target genes were linked to 31 specific signaling pathways. We identified microRNAs specific to accidental head impacts and repetitive headers in soccer, potentially being useful as brain injury biomarkers.

History of traumatic brain injury (TBI) represents a significant risk factor for development of dementia and neurodegenerative disorders in later life. While histopathological sequelae and neurological diagnostics of TBI are well defined, the molecular events linking the post-TBI signaling and neurodegenerative cascades remain unknown. It is not only due to the brain's inaccessibility to direct molecular analysis but also due to the lack of well-defined and highly informative peripheral biomarkers. MicroRNAs (miRNAs) in blood are promising candidates to address this gap. Using integrative bioinformatics pipeline including miRNA:target identification, pathway enrichment, and protein-protein interactions analysis we identified set of genes, interacting proteins, and pathways that are connected to previously reported peripheral miRNAs, deregulated following severe traumatic brain injury (sTBI) in humans. This meta-analysis revealed a spectrum of genes closely related to critical biological processes, such as neuroregeneration including axon guidance and neurite outgrowth, neurotransmission, inflammation, proliferation, apoptosis, cell adhesion, and response to DNA damage. More importantly, we have identified molecular pathways associated with neurodegenerative conditions, including Alzheimer's and Parkinson's diseases, based on purely peripheral markers. The pathway signature after acute sTBI is similar to the one observed in chronic neurodegenerative conditions, which implicates a link between the post-sTBI signaling and neurodegeneration. Identified key hub interacting proteins represent a group of novel candidates for potential therapeutic targets or biomarkers.

Recently emerged SARS-CoV-2 variants show resistance to some antibodies that were authorized for emergency use. We employed hybridoma technology combined with authentic virus assays to develop second-generation antibodies, which were specifically selected for their ability to neutralize new variants of SARS-CoV-2. 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 and B.1.351. Finally, the combination of the two antibodies prevented the appearance of escape mutations of the authentic SARS-CoV-2 virus. The neutralizing properties were fully reproduced in chimeric mouse-human versions, which may represent a promising tool for COVID-19 therapy.

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. The authors present the results of a 24-month phase 2 study of AADvac1, a tau vaccine against Alzheimer’s disease. AADvac1 was safe and induced high levels of antibodies. In the whole study sample, there were no significant changes on clinical outcomes.

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.

International audience; Adult stem cells have become prominent candidates for treating various diseases in veterinary practice. The main goal of our study was therefore to provide a comprehensive study of canine bone marrow-derived mesenchymal stem cells (BMMSC) and conditioned media, isolated from healthy adult dogs of different breeds. Under well-defined standardized isolation protocols, the multipotent differentiation and specific surface markers of BMMSC were supplemented with their gene expression, proteomic profile, and their biological function. The presented data confirm that canine BMMSC express important genes for differentiation toward osteo-, chondro-, and tendo-genic directions, but also genes associated with angiogenic, neurotrophic, and immunomodulatory properties. Furthermore, using proteome profiling, we identify for the first time the dynamic release of various bioactive molecules, such as transcription and translation factors and osteogenic, growth, angiogenic, and neurotrophic factors from canine BMMSC conditioned medium. Importantly, the relevant genes were linked to their proteins as detected in the conditioned medium and further associated with angiogenic activity in chorioallantoic membrane (CAM) assay. In this way, we show that the canine BMMSC release a variety of bioactive molecules, revealing a strong paracrine component that may possess therapeutic potential in various pathologies. However, extensive experimental or preclinical trials testing canine sources need to be performed in order to better understand their paracrine action, which may lead to novel therapeutic strategies in veterinary medicine.

After many decades of research in the field of neurodegeneration, we have no effective cure for Alzheimer's disease (AD), a major form of dementia. It is mainly due to the lack of early, reliable and sensitive biomarkers and incomplete understanding of disease mechanisms at molecular level. Several recently employed biomarkers, especially their combinations, can discriminate advanced stages of AD from other forms of dementia or neuropathy. They do not provide much information on molecular mechanisms of disease rather they reflect the amount of key histopathological markers in the diseased brain. This review is focussed on novel class of potentially very promising AD biomarkers: extracellular miRNAs in body liquids, such as cerebrospinal fluid and blood. They have a great potential not only to indicate the presence of AD, but more importantly, to reflect the molecular mechanisms playing a role early at the beginning of the pathogenic pathways consequently leading to AD. We believe this comprehensive review on deregulated miRNAs in AD can be a good source of information for thorough in silico analyses aiming to identification, development and validation of miRNAs as "diseases mechanism engaged" candidate biomarkers. Having such molecules could bring us closer to the goal - successful treatment of AD.

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.

Alzheimer's disease (AD) is a multifactorial disorder; neurofibrillary pathology composed of tau protein is found side by side with amyloid-β deposits and extensive neuroinflammation. The immune system of the brain is considered as one of the factors that could influence the speed of the progression of AD neuropathology as a potential mediator of the damage induced by AD protein deposits. Alzheimer's disease pathology can be impacted by psychological stress; however, signalling pathways in background are not well known. We have explored possible avenues of how stress could influence the brain's immune system in a rat model of AD. Animals were subjected either to a single or multiple instances of immobilization stress. The analysis of a panel of immunity-related genes was used to evaluate the impact of stress on the immune response in the brain. We have identified 19 stress-responsive genes that are involved in neuroinflammation accompanying tau pathology: Nos2, Ptgs2, IL-8rb, C5, Mmp9, Cx3cr1, CD40lg, Adrb2, IL-6, IL-6r, IL-1r2, Ccl2, Ccl3, Ccl4, Ccl12, TNF-α, IL-1α, IL-1β, IL-10. Most of them are deregulated under the stress conditions also in control animals; however, the magnitude of the response to either acute or chronic stress differs. This can lead to serious influence, most probably to acceleration of neurodegenerative phenotype in diseased animals. Several of the genes (IL-1β, Casp1, Cx3cr1 and C5) are deregulated solely in tauopathic animals. The stress-induced changes in the inflammatory picture of the brain highlight the fact that the brain's immune response is highly responsive to environmental stimuli. The pattern of changes is indicative of an attempt to protect the brain in the short term, while being potentially detrimental to the response against a long-term pathological process such as neurofibrillary degeneration.

Neuroinflammation plays a key role in the pathogenesis of Alzheimer’s disease and related tauopathies. We have previously shown that expression of nonmutated human truncated τ (151-391, 4R), derived from sporadic Alzheimer's disease, induced neurofibrillary degeneration accompanied by microglial and astroglial activation in the brain of transgenic rats. The aim of the current study was to determine the molecular mechanism underlying innate immune response induced by misfolded truncated τ. We found that purified recombinant truncated τ induced morphological transformation of microglia from resting into the reactive phenotype. Simultaneously, truncated τ caused the release of NO, proinflammatory cytokines (IL-1β, IL-6, TNF-α), and tissue inhibitor of metalloproteinase-1 from the mixed glial cultures. Notably, when the pure microglial culture was activated with truncated τ, it displayed significantly higher levels of the proinflammatory cytokines, suggesting a key role of microglia in the τ-mediated inflammatory response. Molecular analysis showed that truncated τ increased the mRNA levels of three MAPKs (JNK, ERK1, p38β) and transcription factors AP-1 and NF-κB that ultimately resulted in enhanced mRNA expression of IL-1β, IL-6, TNF-α, and NO. Our results showed for the first time, to our knowledge, that misfolded truncated protein τ is able to induce innate immune response via a MAPK pathway. Consequently, we suggest that misfolded truncated protein τ represents a viable target for immunotherapy of Alzheimer’s disease.

Transition of protein tau from physiologically unfolded to misfolded state represent enigmatic step in the pathogenesis of tauopathies including Alzheimer’s disease (AD). Major molecular events playing role in this process involve truncation and hyperphosphorylation of tau protein, which are accompanied by redox imbalance followed by functional deterioration of neuronal network. Recently we have developed transgenic rat model showing that expression of truncated tau causes neurofibrillary degeneration similar to that observed in brain of AD sufferers. Consequently we tested cortical and hippocampal neuronal cultures extracted from this model as a convenient tool for development of molecules able to target the mechanisms leading to and/or enhancing the process of neurodegeneration. Here we document three major pathological features typical for tauopathies and AD in cortical and hippocampal neurons from transgenic rat in vitro. First, an increased accumulation of human truncated tau in neurons; second, the hyperphosphorylation of truncated tau on the epitopes characteristic of AD (Ser202/Thr205 and Thr231); and third, increased vulnerability of the neurons to nitrative and oxidative stress. Our results show that primary neurons expressing human truncated tau could represent a cellular model for targeting tau related pathological events, namely, aberrant tau protein accumulation, tau hyperphosphorylation, and oxidative/nitrative damage. These characteristics make the model particularly suitable for detailed study of molecular mechanisms of tau induced neurodegeneration and easily applicable for drug screening.

We have previously shown that human misfolded tau proteins strongly perturb mitochondrial transport and induce accumulation of free radicals in neurons. This interference is underlying cause of increased susceptibility to oxidative stress and could be linked to excitotoxic pathways. In order to understand integral mechanisms of misfolded tau driven neurodegeneration, we have investigated the role of human truncated tau protein, derived from Alzheimer’s disease, in rat cortical neurons under the conditions of excitotoxic stress induced by glutamate. We found that primary neurons expressing truncated tau protein are highly susceptible to glutamate-induced cell death. Pre-treatment with memantine (N-methyl-d-aspartate receptor antagonist) significantly improved survival of rat neurons exposed to glutamate and its effect was associated with overall decrease of reactive oxygen species (ROS) in both transgenic and nontransgenic neurons. Interestingly, despite of this overall effect, memantine was not able to decrease misfolded tau-induced ROS level specifically in transgenic cells. Our data suggest that memantine does not interfere with specific pathological pathways induced by misfolded tau protein nevertheless is able to attenuate oxidative stress in neurons.