Protective Effects of Flavonoids Against Mitochondriopathies and Associated Pathologies: Focus on the Predictive Approach and Personalized Prevention.

Multi-factorial mitochondrial damage exhibits a "vicious circle" that leads to a progression of mitochondrial dysfunction and multi-organ adverse effects. Mitochondrial impairments (mitochondriopathies) are associated with severe pathologies including but not restricted to cancers, cardiovascular diseases, and neurodegeneration. However, the type and level of cascading pathologies are highly individual. Consequently, patient stratification, risk assessment, and mitigating measures are instrumental for cost-effective individualized protection. Therefore, the paradigm shift from reactive to predictive, preventive, and personalized medicine (3PM) is unavoidable in advanced healthcare. Flavonoids demonstrate evident antioxidant and scavenging activity are of great therapeutic utility against mitochondrial damage and cascading pathologies. In the context of 3PM, this review focuses on preclinical and clinical research data evaluating the efficacy of flavonoids as a potent protector against mitochondriopathies and associated pathologies.

Who fans the flames of Alzheimer's disease brains? Misfolded tau on the crossroad of neurodegenerative and inflammatory pathways.

Neurodegeneration, induced by misfolded tau protein, and neuroinflammation, driven by glial cells, represent the salient features of Alzheimer's disease (AD) and related human tauopathies. While tau neurodegeneration significantly correlates with disease progression, brain inflammation seems to be an important factor in regulating the resistance or susceptibility to AD neurodegeneration. Previously, it has been shown that there is a reciprocal relationship between the local inflammatory response and neurofibrillary lesions. Numerous independent studies have reported that inflammatory responses may contribute to the development of tau pathology and thus accelerate the course of disease. It has been shown that various cytokines can significantly affect the functional and structural properties of intracellular tau. Notwithstanding, anti-inflammatory approaches have not unequivocally demonstrated that inhibition of the brain immune response can lead to reduction of neurofibrillary lesions. On the other hand, our recent data show that misfolded tau could represent a trigger for microglial activation, suggesting the dual role of misfolded tau in the Alzheimer's disease inflammatory cascade. On the basis of current knowledge, we can conclude that misfolded tau is located at the crossroad of the neurodegenerative and neuroinflammatory pathways. Thus disease-modified tau represents an important target for potential therapeutic strategies for patients with Alzheimer's disease.

Antithrombotic and antiplatelet effects of plant-derived compounds: a great utility potential for primary, secondary, and tertiary care in the framework of 3P medicine.

Thromboembolism is the third leading vascular disease, with a high annual incidence of 1 to 2 cases per 1000 individuals within the general population. The broader term venous thromboembolism generally refers to deep vein thrombosis, pulmonary embolism, and/or a combination of both. Therefore, thromboembolism can affect both - the central and peripheral veins. Arterial thromboembolism causes systemic ischemia by disturbing blood flow and oxygen supply to organs, tissues, and cells causing, therefore, apoptosis and/or necrosis in the affected tissues. Currently applied antithrombotic drugs used, e.g. to protect affected individuals against ischemic stroke, demonstrate significant limitations. For example, platelet inhibitors possess only moderate efficacy. On the other hand, thrombolytics and anticoagulants significantly increase hemorrhage. Contextually, new approaches are extensively under consideration to develop next-generation antithrombotics with improved efficacy and more personalized and targeted application. To this end, phytochemicals show potent antithrombotic efficacy demonstrated in numerous in vitro, ex vivo, and in vivo models as well as in clinical evaluations conducted on healthy individuals and persons at high risk of thrombotic events, such as pregnant women (primary care), cancer, and COVID-19-affected patients (secondary and tertiary care). Here, we hypothesized that specific antithrombotic and antiplatelet effects of plant-derived compounds might be of great clinical utility in primary, secondary, and tertiary care. To increase the efficacy, precise patient stratification based on predictive diagnostics is essential for targeted protection and treatments tailored to the person in the framework of 3P medicine. Contextually, this paper aims at critical review toward the involvement of specific classes of phytochemicals in antiplatelet and anticoagulation adapted to clinical needs. The paper exemplifies selected plant-derived drugs, plant extracts, and whole plant foods/herbs demonstrating their specific antithrombotic, antiplatelet, and fibrinolytic activities relevant for primary, secondary, and tertiary care. One of the examples considered is antithrombotic and antiplatelet protection specifically relevant for COVID-19-affected patient groups.

Genetic background modifies neurodegeneration and neuroinflammation driven by misfolded human tau protein in rat model of tauopathy: implication for immunomodulatory approach to Alzheimer's disease.

BACKGROUND: Numerous epidemiological studies demonstrate that genetic background modifies the onset and the progression of Alzheimer's disease and related neurodegenerative disorders. The efficacious influence of genetic background on the disease pathway of amyloid beta has been meticulously described in rodent models. Since the impact of genetic modifiers on the neurodegenerative and neuroinflammatory cascade induced by misfolded tau protein is yet to be elucidated, we have addressed the issue by using transgenic lines expressing the same human truncated tau protein in either spontaneously hypertensive rat (SHR) or Wistar-Kyoto (WKY) genetic background. METHODS: Brains of WKY and SHR transgenic rats in the terminal stage of phenotype and their age-matched non-transgenic littermates were examined by means of immunohistochemistry and unbiased stereology. Basic measures of tau-induced neurodegeneration (load of neurofibrillary tangles) and neuroinflammation (number of Iba1-positive microglia, their activated morphology, and numbers of microglia immunoreactive for MHCII and astrocytes immunoreactive for GFAP) were quantified with an optical fractionator in brain areas affected by neurofibrillary pathology (pons, medulla oblongata). The stereological data were evaluated using two-way ANOVA and Student's t-test. RESULTS: Tau neurodegeneration (neurofibrillary tangles (NFTs), axonopathy) and neuroinflammation (microgliosis, astrocytosis) appeared in both WKY and SHR transgenic rats. Although identical levels of transgene expression in both lines were present, terminally-staged WKY transgenic rats displayed significantly lower final NFT loads than their SHR transgenic counterparts. Interestingly, microglial responses showed a striking difference between transgenic lines. Only 1.6% of microglia in SHR transgenic rats expressed MHCII in spite of having a robust phagocytic phenotype, whereas in WKY transgenic rats, 23.2% of microglia expressed MHCII despite displaying a considerably lower extent of transformation into phagocytic phenotype. CONCLUSIONS: These results show that the immune response represents a pivotal and genetically variable modifying factor that is able to influence vulnerability to neurodegeneration. Therefore, targeted immunomodulation could represent a prospective therapeutic approach to Alzheimer's disease.

Carotenoids in Cancer Metastasis-Status Quo and Outlook.

Metastasis represents a major obstacle in cancer treatment and the leading cause of cancer-related deaths. Therefore, the identification of compounds targeting the multi-step and complex process of metastasis could improve outcomes in the management of cancer patients. Carotenoids are naturally occurring pigments with a plethora of biological activities. Carotenoids exert a potent anti-cancer capacity in various cancer models in vitro and in vivo, mediated by the modulation of signaling pathways involved in the migration and invasion of cancer cells and metastatic progression, including key regulators of the epithelial-mesenchymal transition and regulatory molecules, such as matrix metalloproteinases (MMPs), tissue inhibitors of metalloproteinases (TIMPs), urokinase plasminogen activator (uPA) and its receptor (uPAR), hypoxia-inducible factor-1α (HIF-1α), and others. Moreover, carotenoids modulate the expression of genes associated with cancer progression and inflammatory processes as key mediators of the complex process involved in metastasis. Nevertheless, due to the predominantly preclinical nature of the known anti-tumor effects of carotenoids, and unclear results from certain carotenoids in specific cancer types and/or specific parts of the population, a precise analysis of the anti-cancer effects of carotenoids is essential. The identification of carotenoids as effective compounds targeting the complex process of cancer progression could improve the outcomes of advanced cancer patients.

Implications of flavonoids as potential modulators of cancer neovascularity.

PURPOSE: The formation of new blood vessels from previous ones, angiogenesis, is critical in tissue repair, expansion or remodeling in physiological processes and in various pathologies including cancer. Despite that, the development of anti-angiogenic drugs has great potential as the treatment of cancer faces many problems such as development of the resistance to treatment or an improperly selected therapy approach. An evaluation of predictive markers in personalized medicine could significantly improve treatment outcomes in many patients. METHODS: This comprehensive review emphasizes the anticancer potential of flavonoids mediated by their anti-angiogenic efficacy evaluated in current preclinical and clinical cancer research. RESULTS AND CONCLUSION: Flavonoids are important groups of phytochemicals present in common diet. Flavonoids show significant anticancer effects. The anti-angiogenic effects of flavonoids are currently a widely discussed topic of preclinical cancer research. Flavonoids are able to regulate the process of tumor angiogenesis through modulation of signaling molecules such as VEGF, MMPs, ILs, HIF or others. However, the evaluation of the anti-angiogenic potential of flavonoids within the clinical studies is not frequently discussed and is still of significant scientific interest.

Beyond the rat models of human neurodegenerative disorders.

The rat is a model of choice in biomedical research for over a century. Currently, the rat presents the best "functionally" characterized mammalian model system. Despite this fact, the transgenic rats have lagged behind the transgenic mice as an experimental model of human neurodegenerative disorders. The number of transgenic rat models recapitulating key pathological hallmarks of Alzheimer's disease, Huntington's disease, amyotrophic lateral sclerosis, or human tauopathies is still limited. The reason is that the transgenic rats remain more difficult to produce than transgenic mice. The gene targeting technology is not yet established in rats due to the lack of truly totipotent embryonic stem cells and cloning technology. This extremely powerful technique has given the mouse a clear advantage over the rat in generation of new transgenic models. Despite these limitations, transgenic rats have greatly expanded the range of potential experimental approaches. The large size of rats permits intrathecal administration of drugs, stem cell transplantation, serial sampling of the cerebrospinal fluid, microsurgical techniques, in vivo nerve recordings, and neuroimaging procedures. Moreover, the rat is routinely employed to demonstrate therapeutic efficacy and to assess toxicity of novel therapeutic compounds in drug development. Here we suggest that the rat constitutes a slightly underestimated but perspective animal model well-suited for understanding the mechanisms and pathways underlying the human neurodegenerative disorders.

NeuroScale, the battery of behavioral tests with novel scoring system for phenotyping of transgenic rat model of tauopathy.

We have previously shown that transgenic rats expressing misfolded tau protein developed neurofibrillary tangles and axonal degeneration in the brain and spinal cord, which led to impairment of sensorimotor and neuromuscular functions. To quantify neurobehavioral phenotype of the transgenic rats we have designed a testing protocol and a novel scoring system - NeuroScale - that reliably reflects progression of functional impairment of transgenic rats. NeuroScale consists of three variants of beam walking test with different sensitivity and a rapid neuromuscular and neurological examination, where animal performance is evaluated and scored according to a pre-defined rating scale. The range of the rating scale was developed to increase homogeneity of the collected behavioral data without lowering sensitivity of the testing methods. Finally, all awarded points were summed up to obtain a complete quantitative behavioral readout, the NeuroScale score, from animals under investigation. Increase in the NeuroScale score faithfully mirrored disease progression and allowed statistically significant discrimination (p<0.001) between behavioral responses of transgenic and control animals during the whole disease process. The method was suitable for a high-throughput test whereby an experienced operator can examine up to 60 rats per day. We show that this multi-test battery with novel sensitive scoring system - NeuroScale - represents a rapid, simple to perform, high throughput method for quantitative evaluation of behavioral phenotype of transgenic rats that could serve as a valuable primary read-out for in vivo validation of therapeutic agents.

DNA Methylation Status in Cancer Disease: Modulations by Plant-Derived Natural Compounds and Dietary Interventions.

The modulation of the activity of DNA methyltransferases (DNMTs) represents a crucial epigenetic mechanism affecting gene expressions or DNA repair mechanisms in the cells. Aberrant modifications in the function of DNMTs are a fundamental event and part of the pathogenesis of human cancer. Phytochemicals, which are biosynthesized in plants in the form of secondary metabolites, represent an important source of biomolecules with pleiotropic effects and thus provide a wide range of possible clinical applications. It is well documented that phytochemicals demonstrate significant anticancer properties, and in this regard, rapid development within preclinical research is encouraging. Phytochemicals affect several epigenetic molecular mechanisms, including DNA methylation patterns such as the hypermethylation of tumor-suppressor genes and the global hypomethylation of oncogenes, that are specific cellular signs of cancer development and progression. This review will focus on the latest achievements in using plant-derived compounds and plant-based diets targeting epigenetic regulators and modulators of gene transcription in preclinical and clinical research in order to generate novel anticancer drugs as sensitizers for conventional therapy or compounds suitable for the chemoprevention clinical setting in at-risk individuals. In conclusion, indisputable anticancer activities of dietary phytochemicals linked with proper regulation of DNA methylation status have been described. However, precisely designed and well-controlled clinical studies are needed to confirm their beneficial epigenetic effects after long-term consumption in humans.

A comparative study on pathological features of transgenic rat lines expressing either three or four repeat misfolded tau.

Human tauopathies represent a heterogeneous group of neurodegenerative disorders characterized by distinct clinical features, typical histopathological structures, and defined ratio(s) of three-repeat and four-repeat tau isoforms within pathological aggregates. How the optional microtubule-binding repeat of tau influences this differentiation of pathologies is understudied. We have previously generated and characterized transgenic rodent models expressing human truncated tau aa151-391 with either three (SHR24) or four microtubule-binding repeats (SHR72). Here, we compare the behavioral and neuropathological hallmarks of these two transgenic lines using a battery of tests for sensorimotor, cognitive, and neurological functions over the age range of 3.5-15 months. Progression of sensorimotor and neurological deficits was similar in both transgenic lines; however, the lifespan of transgenic line SHR72 expressing truncated four-repeat tau was markedly shorter than SHR24. Moreover, the expression of three or four-repeat tau induced distinct neurofibrillary pathology in these lines. Transgenic lines displayed different distribution of tau pathology and different type of neurofibrillary tangles. Our results suggest that three- and four-repeat isoforms of tau may display different modes of action in the diseased brain.

First transgenic rat model developing progressive cortical neurofibrillary tangles.

Neurofibrillary degeneration induced by misfolded protein tau is considered to be one of the key pathological hallmarks of Alzheimer's disease (AD). In the present study, we have introduced a novel transgenic rat model expressing a human truncated tau that encompasses 3 microtubule binding domains (3R) and a proline-rich region (3R tau151-391). The transgenic rats developed progressive age-dependent neurofibrillary degeneration in the cortical brain areas. Neurofibrillary tangles (NFTs) satisfied several key histological criteria used to identify neurofibrillary degeneration in human Alzheimer's disease including argyrophilia, Congo red birefringence, and Thioflavin S reactivity. Neurofibrillary tangles were also identified with antibodies used to detect pathologic tau in the human brain, including DC11, recognizing an abnormal tau conformation and antibodies that are specific for hyperphosphorylated forms of tau protein. Moreover, neurofibrillary degeneration was characterized by extensive formation of sarkosyl insoluble tau protein complexes consisting of rat endogenous and truncated tau species. Interestingly, the transgenic rats did not show neuronal loss either in the cortex or in the hippocampus. We suggest that novel transgenic rat model for human tauopathy represents a valuable tool in preclinical drug discovery targeting neurofibrillary degeneration of Alzheimer's type.

Human misfolded truncated tau protein promotes activation of microglia and leukocyte infiltration in the transgenic rat model of tauopathy.

It has been hypothesized that misfolded tau protein could be a mediator of the inflammatory response in human tauopathies. Here we show that neurodegenerative lesions caused by human truncated tau promote inflammatory response manifested by upregulation of immune-molecules (CD11a,b, CD18, CD4, CD45 and CD68) and morphological activation of microglial cells in a rat model of tauopathy. In parallel, the innate immune brain response promotes activation of MHC class II positive blood-borne leukocytes and their influx into the brain parenchyma. These findings have important consequences for the rationale drug development of effective inflammation-based therapeutic strategies for human tauopathies.