Combined induction of mTOR-dependent and mTOR-independent pathways of autophagy activation as an experimental therapy for Alzheimer's disease-like pathology in a mouse model.

Alzheimer's disease (AD) is associated with amyloid-ß (Aß) accumulation that might be hindered by autophagy. There are two ways to induce autophagy: through mTOR-dependent and mTOR-independent pathways (here, by means of rapamycin and trehalose, respectively). The aim of this study was to evaluate the contribution of these pathways and their combination to the treatment of experimental AD. Mice were injected bilaterally intracerebroventricularly with an Aß fragment (25-35) to set up an AD model. Treatment with rapamycin (10 mg/kg, every other day), trehalose consumption with drinking water (2 mg/mL, ad libitum), or their combination started 2 days after the surgery and lasted for 2 weeks. Open-field, plus-maze, and passive avoidance tests were used for behavioral phenotyping. Neuronal density, Aß accumulation, and the expression of autophagy marker LC3-II and neuroinflammatory marker IBA1 were measured in the frontal cortex and hippocampus. mRNA levels of autophagy genes (Atg8, Becn1, and Park2) were assessed in the hippocampus. Trehalose but not rapamycin caused pronounced prolonged autophagy induction and transcriptional activation of autophagy genes. Both drugs effectively prevented Aß deposition and microglia activation. Autophagy inhibitor 3-methyladenine significantly attenuated autophagy activation and disturbed the effect of the inducers on Aß load. The inducers substantially reversed behavioral and neuronal deficits in Aß-injected mice. In many cases, the best outcomes were achieved with the combined treatment. Thus, trehalose alone or combined autophagy activation by the two inducers may be a promising treatment approach to AD-like neurodegeneration. Some aspects of interaction between mTOR-dependent and mTOR-independent pathways of autophagy are discussed.

Trehalose Activates Hepatic and Myocardial Autophagy and Has Anti-Inflammatory Effects in db/db Diabetic Mice.

Db/db mice (carrying a mutation in the gene encoding leptin receptor) show autophagy suppression. Our aim was to evaluate the effect of autophagy inducer trehalose on liver and heart autophagy in db/db mice and to study inflammation dysregulation and the suitability of chitinases' expression levels as diabetes markers. Thirty-eight male db/db mice and C57/BL mice (control) were used. The db/db model manifested inflammation symptoms: overexpression of TNF-α in the spleen and underexpression of IL-10 in the liver and spleen (cytokine imbalance). Simultaneously, we revealed decreased expression of chitotriosidase (CHIT1) and acid mammalian chitinase (CHIA) in the liver of db/db mice. CHIA expression in db/db mice is significantly lower only in the spleen. Trehalose treatment significantly reduced blood glucose concentration and glycated hemoglobin. Treatment of db/db mice by trehalose was followed by increased autophagy induction in the heart and liver (increased autolysosomes volume density studied by morphometric electron-microscopic method). Trehalose exerted beneficial cardiac effects possibly via increased lipophagy (uptake of lipid droplets). The autophagy activation by trehalose had several positive effects on the heart and liver of db/db mice; therefore, lipophagy activation seems to be a promising therapy for diabetes.

Cystatin C and cystatin SN as possible soluble tumor markers in malignant uveal melanoma.

BACKGROUND: The aim of the study was to determine the concentration of endogenous cystatin C and cystatin SN, as potential tumor biomarkers, in the serum and biological fluids of the eye in both healthy controls and patients with uveal melanoma. PATIENTS AND METHODS: The concentration of both cystatins was determined in the intraocular fluid (IOF), tear fluid, and serum of patients with uveal melanoma and compared to baseline measurements in IOF, tears, serum, cerebral spinal fluid, saliva and urine of healthy controls. RESULTS: The concentration of cystatin C in all the biological matrices obtained from healthy controls significantly exceeded the concentration of cystatin SN and was independent of gender. Cystatin C concentrations in the tear fluid of patients with uveal melanoma (both the eye with the malignancy, as well as the contralateral, non-affected eye), were significantly greater than cystatin C concentrations in the tear fluid of healthy controls and was independent of tumor size. The concentration of cystatin SN in IOF of patients with uveal melanoma was significantly less than the corresponding concentration of cystatin SN in healthy controls. CONCLUSIONS: The ratio of cystatins (CysC:CysSN) in both the serum and tear fluid, as well as the concentration of cystatin SN in IOF, would appear to strongly suggest the presence of uveal melanoma. It is further suggested that multiple diagnostic criteria be utilized if a patient is suspected of having uveal melanoma, such as determination of the cystatin C and cystatin SN concentrations in serum, tears, and IOF, ocular fundus and ultrasound imaging, and biopsy with histopathological evaluation.

Treatment with Autophagy Inducer Trehalose Alleviates Memory and Behavioral Impairments and Neuroinflammatory Brain Processes in db/db Mice.

Autophagy attenuation has been found in neurodegenerative diseases, aging, diabetes mellitus, and atherosclerosis. In experimental models of neurodegenerative diseases, the correction of autophagy in the brain reverses neuronal and behavioral deficits and hence seems to be a promising therapy for neuropathologies. Our aim was to study the effect of an autophagy inducer, trehalose, on brain autophagy and behavior in a genetic model of diabetes with signs of neuronal damage (db/db mice). A 2% trehalose solution was administered as drinking water during 24 days of the experiment. Expressions of markers of autophagy (LC3-II), neuroinflammation (IBA1), redox state (NOS), and neuronal density (NeuN) in the brain were assessed by immunohistochemical analysis. For behavioral phenotyping, the open field, elevated plus-maze, tail suspension, pre-pulse inhibition, and passive avoidance tests were used. Trehalose caused a slight reduction in increased blood glucose concentration, considerable autophagy activation, and a decrease in the neuroinflammatory response in the brain along with improvements of exploration, locomotor activity, anxiety, depressive-like behavior, and fear learning and memory in db/db mice. Trehalose exerted some beneficial peripheral and systemic effects and partially reversed behavioral alterations in db/db mice. Thus, trehalose as an inducer of mTOR-independent autophagy is effective at alleviating neuronal and behavioral disturbances accompanying experimental diabetes.

Effects of Medicinal Fungi-Derived ß-Glucan on Tumor Progression.

ß-Glucans have been studied in animal species, from earthworms to humans. They form a heterogenous group of glucose polymers found in fungi, plants, bacteria, and seaweed. ß-Glucans have slowly emerged as an important target for the recognition of pathogens. In the current review, we highlight the major roles of mushroom-derived ß-glucans on cancer progression.

Lysosomotropic Features and Autophagy Modulators among Medical Drugs: Evaluation of Their Role in Pathologies.

The concept of lysosomotropic agents significantly changed numerous aspects of cellular biochemistry, biochemical pharmacology, and clinical medicine. In the present review, we focused on numerous low-molecular and high-molecular lipophilic basic compounds and on the role of lipophagy and autophagy in experimental and clinical medicine. Attention was primarily focused on the most promising agents acting as autophagy inducers, which offer a new window for treatment and/or prophylaxis of various diseases, including type 2 diabetes mellitus, Parkinson's disease, and atherosclerosis. The present review summarizes current knowledge on the lysosomotropic features of medical drugs, as well as autophagy inducers, and their role in pathological processes.

The Pluripotency Factor Nanog Protects against Neuronal Amyloid ß-Induced Toxicity and Oxidative Stress through Insulin Sensitivity Restoration.

Amyloid ß (Aß) is a peptide fragment of the amyloid precursor protein that triggers the progression of Alzheimer's Disease (AD). It is believed that Aß contributes to neurodegeneration in several ways, including mitochondria dysfunction, oxidative stress and brain insulin resistance. Therefore, protecting neurons from Aß-induced neurotoxicity is an effective strategy for attenuating AD pathogenesis. Recently, applications of stem cell-based therapies have demonstrated the ability to reduce the progression and outcome of neurodegenerative diseases. Particularly, Nanog is recognized as a stem cell-related pluripotency factor that enhances self-renewing capacities and helps reduce the senescent phenotypes of aged neuronal cells. However, whether the upregulation of Nanog can be an effective approach to alleviate Aß-induced neurotoxicity and senescence is not yet understood. In the present study, we transiently overexpressed Nanog-both in vitro and in vivo-and investigated the protective effects and underlying mechanisms against Aß. We found that overexpression of Nanog is responsible for attenuating Aß-triggered neuronal insulin resistance, which restores cell survival through reducing intracellular mitochondrial superoxide accumulation and cellular senescence. In addition, upregulation of Nanog expression appears to increase secretion of neurotrophic factors through activation of the Nrf2 antioxidant defense pathway. Furthermore, improvement of memory and learning were also observed in rat model of Aß neurotoxicity mediated by upregulation of Nanog in the brain. Taken together, our study suggests a potential role for Nanog in attenuating the neurotoxic effects of Aß, which in turn, suggests that strategies to enhance Nanog expression may be used as a novel intervention for reducing Aß neurotoxicity in the AD brain.

Hypolipidemic Effects of ß-Glucans, Mannans, and Fucoidans: Mechanism of Action and Their Prospects for Clinical Application.

The search for lipid-lowering drugs is important for clinical medicine. This review summarizes our research findings regarding the hypolipidemic activity of polysaccharides. There are several validated agents altering lipid levels which reduce the risk of atherosclerotic cardiovascular events. Nonetheless, for many people, the risk of such an event remains unacceptably high despite treatment with these agents. This situation has prompted the search for new therapies to reduce the residual cardiovascular risk. The lipid-lowering effect of ß-glucans consumed with food was demonstrated in patients with atherosclerosis. The mechanism of the protective effect of ß-glucans is poorly studied. The effects of ß-glucans are mediated by Toll-like receptors, by dectin-1, and possibly by other receptors. Nevertheless, the mechanism of the protective action of ß-glucan in lipemic mice has been studied insufficiently. This review will present up-to-date information regarding experimental hypolipidemic polysaccharide compounds that hold promise for medicine. Phagocyte-specific chitotriosidase in humans contributes to innate immune responses against chitin-containing fungi. This enzyme has been first described in patients with Gaucher disease and serves as an important diagnostic biomarker. It has been reported that, in mice, chitin particles of certain size are recognized by macrophages through Toll-like receptors, dectin-1, and to a lesser extent through mannose receptor.

Glucan and Mannan-Two Peas in a Pod.

In recent decades, various polysaccharides isolated from algae, mushrooms, yeast, and higher plants have attracted serious attention in the area of nutrition and medicine. The reasons include their low toxicity, rare negative side effects, relatively low price, and broad spectrum of therapeutic actions. The two most and best-studied polysaccharides are mannan and glucan. This review focused on their biological properties.

GLP-1 Analogue Liraglutide Attenuates Mutant Huntingtin-Induced Neurotoxicity by Restoration of Neuronal Insulin Signaling.

Huntington's disease (HD) is a progressive and fatal neurodegenerative disease caused by CAG repeat expansion in the coding region of huntingtin (HTT) protein. The accumulation of mutant HTT (mHTT) contributes to neurotoxicity by causing autophagy defects and oxidative stress that ultimately lead to neuronal death. Interestingly, epidemiologic studies have demonstrated that the prevalence of type-2 diabetes, a metabolic disease mainly caused by defective insulin signaling, is higher in patients with HD than in healthy controls. Although the precise mechanisms of mHTT-mediated toxicity remain unclear, the blockade of brain insulin signaling may initiate or exacerbate mHTT-induced neurodegeneration. In this study, we used an in vitro HD model to investigate whether neuronal insulin signaling is involved in mHTT-mediated neurotoxicity. Our results demonstrated that mHTT overexpression significantly impairs insulin signaling and causes apoptosis in neuronal cells. However, treatment with liraglutide, a GLP-1 analogue, markedly restores insulin sensitivity and enhances cell viability. This neuroprotective effect may be attributed to the contribution of the upregulated expression of genes associated with endogenous antioxidant pathways to oxidative stress reduction. In addition, liraglutide stimulates autophagy through AMPK activation, which attenuates the accumulation of HTT aggregates within neuronal cells. Our findings collectively suggest that liraglutide can rescue impaired insulin signaling caused by mHTT and that GLP-1 may potentially reduce mHTT-induced neurotoxicity in the pathogenesis of HD.

Suppression of autophagy in the brain of transgenic mice with overexpression of А53Т-mutant α-synuclein as an early event at synucleinopathy progression.

Transgenic overexpression of α-synuclein is a common model of Parkinson's disease (PD). Accumulation of А53Т-mutant α-synuclein induces three autophagy cell responses: the inhibition of autophagy caused by the accumulation of α-synuclein, compensatory activation of macroautophagy in response to inhibition of the chaperone-mediated autophagy, and toxic effects of mutant α-synuclein accompanied by the activation of autophagy. The overall effect of long-term overexpression of mutant α-synuclein in vivo remains unclear. Here we evaluated the activity of autophagy in the frontal cortex, striatum and s.nigra of transgenic mice with overexpression of А53Т-mutant α-synuclein. We revealed low autophagic activity in the dopaminergic structures of 5 mo. transgenic B6.Cg-Tg(Prnp-SNCA*A53T)23Mkle/J mice as compared to controls C57Bl/6J mice. The results were further supported by the data on tyrosine hydroxylase immunostaining that indicated its significant decrease in the striatum but not in s.nigra of transgenic mice and might be more related to earlier damage of dopaminergic neurites than to the somas due to disturbed formation of autophagosomes at the neuron periphery. The results provide evidence of a possible contribution of suppressed autophagy to the development of PD-like condition as an early event at synucleinopathy progression. Activation of autophagy at early stages of PD seems to be a promising therapeutic tool while B6.Cg-Tg(Prnp-SNCA*A53T)23Mkle/J mice are suggested as a suitable and adequate model for studying the neuroprotective potential and value of this approach.