Pharmacological inhibition of the CB1 cannabinoid receptor restores abnormal brain mitochondrial CB1 receptor expression and rescues bioenergetic and cognitive defects in a female mouse model of Rett syndrome.

BACKGROUND: Defective mitochondria and aberrant brain mitochondrial bioenergetics are consistent features in syndromic intellectual disability disorders, such as Rett syndrome (RTT), a rare neurologic disorder that severely affects mainly females carrying mutations in the X-linked MECP2 gene. A pool of CB1 cannabinoid receptors (CB1R), the primary receptor subtype of the endocannabinoid system in the brain, is located on brain mitochondrial membranes (mtCB1R), where it can locally regulate energy production, synaptic transmission and memory abilities through the inhibition of the intra-mitochondrial protein kinase A (mtPKA). In the present study, we asked whether an overactive mtCB1R-mtPKA signaling might underlie the brain mitochondrial alterations in RTT and whether its modulation by systemic administration of the CB1R inverse agonist rimonabant might improve bioenergetics and cognitive defects in mice modeling RTT. METHODS: Rimonabant (0.3 mg/kg/day, intraperitoneal injections) was administered daily to symptomatic female mice carrying a truncating mutation of the Mecp2 gene and its effects on brain mitochondria functionality, systemic oxidative status, and memory function were assessed. RESULTS: mtCB1R is overexpressed in the RTT mouse brain. Subchronic treatment with rimonabant normalizes mtCB1R expression in RTT mouse brains, boosts mtPKA signaling, and restores the defective brain mitochondrial bioenergetics, abnormal peripheral redox homeostasis, and impaired cognitive abilities in RTT mice. LIMITATIONS: The lack of selectivity of the rimonabant treatment towards mtCB1R does not allow us to exclude that the beneficial effects exerted by the treatment in the RTT mouse model may be ascribed more broadly to the modulation of CB1R activity and distribution among intracellular compartments, rather than to a selective effect on mtCB1R-mediated signaling. The low sample size of few experiments is a further limitation that has been addressed replicating the main findings under different experimental conditions. CONCLUSIONS: The present data identify mtCB1R overexpression as a novel molecular alteration in the RTT mouse brain that may underlie defective brain mitochondrial bioenergetics and cognitive dysfunction.

Brain Mitochondrial Bioenergetics in Genetic Neurodevelopmental Disorders: Focus on Down, Rett and Fragile X Syndromes.

Mitochondria, far beyond their prominent role as cellular powerhouses, are complex cellular organelles active as central metabolic hubs that are capable of integrating and controlling several signaling pathways essential for neurological processes, including neurogenesis and neuroplasticity. On the other hand, mitochondria are themselves regulated from a series of signaling proteins to achieve the best efficiency in producing energy, in establishing a network and in performing their own de novo synthesis or clearance. Dysfunctions in signaling processes that control mitochondrial biogenesis, dynamics and bioenergetics are increasingly associated with impairment in brain development and involved in a wide variety of neurodevelopmental disorders. Here, we review recent evidence proving the emerging role of mitochondria as master regulators of brain bioenergetics, highlighting their control skills in brain neurodevelopment and cognition. We analyze, from a mechanistic point of view, mitochondrial bioenergetic dysfunction as causally interrelated to the origins of typical genetic intellectual disability-related neurodevelopmental disorders, such as Down, Rett and Fragile X syndromes. Finally, we discuss whether mitochondria can become therapeutic targets to improve brain development and function from a holistic perspective.

Serious Games in the new era of digital-health interventions: A narrative review of their therapeutic applications to manage neurobehavior in neurodevelopmental disorders.

Children and adolescents with neurodevelopmental disorders generally show adaptive, cognitive and motor skills impairments associated with behavioral problems, i.e., alterations in attention, anxiety and stress regulation, emotional and social relationships, which strongly limit their quality of life. This narrative review aims at providing a critical overview of the current knowledge in the field of serious games (SGs), known as digital instructional interactive videogames, applied to neurodevelopmental disorders. Indeed, a growing number of studies is drawing attention to SGs as innovative and promising interventions in managing neurobehavioral and cognitive disturbs in children with neurodevelopmental disorders. Accordingly, we provide a literature overview of the current evidence regarding the actions and the effects of SGs. In addition, we describe neurobehavioral alterations occurring in some specific neurodevelopmental disorders for which a possible therapeutic use of SGs has been suggested. Finally, we discuss findings obtained in clinical trials using SGs as digital therapeutics in neurodevelopment disorders and suggest new directions and hypotheses for future studies to bridge the gaps between clinical research and clinical practice.

Chronic treatment with the anti-diabetic drug metformin rescues impaired brain mitochondrial activity and selectively ameliorates defective cognitive flexibility in a female mouse model of Rett syndrome.

Metformin is the most common anti-diabetic drug and a promising therapy for disorders beyond diabetes, including Rett syndrome (RTT), a rare neurologic disease characterized by severe intellectual disability. A 10-day-long treatment rescued aberrant mitochondrial activity and restrained oxidative stress in a female RTT mouse model. However, this treatment regimen did not improve the phenotype of RTT mice. In the present study, we demonstrate that a 4-month-long treatment with metformin (150 mg/Kg/day, delivered in drinking bottles) provides a selective normalization of cognitive flexibility defects in RTT female mice at an advanced stage of disease, but it does not affect their impaired general health status and abnormal motor skills. The 4-month-long treatment also rescues the reduced activity of mitochondrial respiratory chain complex activities, the defective brain ATP production and levels as well as the increased production of reactive oxidizing species in the whole blood of RTT mice. A significant boost of PGC-1α-dependent pathways related to mitochondrial biogenesis and antioxidant defense occurs in the brain of RTT mice that received the metformin treatment. Further studies will have to verify whether these effects may underlie its long-lasting beneficial effects on brain energy metabolism.

The Underestimated Role of the p53 Pathway in Renal Cancer.

The TP53 tumor suppressor gene is known as the guardian of the genome, playing a pivotal role in controlling genome integrity, and its functions are lost in more than 50% of human tumors due to somatic mutations. This percentage rises to 90% if mutations and alterations in the genes that code for regulators of p53 stability and activity are taken into account. Renal cell carcinoma (RCC) is a clear example of cancer that despite having a wild-type p53 shows poor prognosis because of the high rate of resistance to radiotherapy or chemotherapy, which leads to recurrence, metastasis and death. Remarkably, the fact that p53 is poorly mutated does not mean that it is functionally active, and increasing experimental evidences have demonstrated this. Therefore, RCC represents an extraordinary example of the importance of p53 pathway alterations in therapy resistance. The search for novel molecular biomarkers involved in the pathways that regulate altered p53 in RCC is mandatory for improving early diagnosis, evaluating the prognosis and developing novel potential therapeutic targets for better RCC treatment.

Primary and Secondary Mitochondrial Diseases: Etiologies and Therapeutic Strategies.

Mitochondria are complex and multifaceted organelles that constitute a dynamic network of signaling platforms playing a pivotal role in cellular energy-generating processes [...].

Mitochondria Can Cross Cell Boundaries: An Overview of the Biological Relevance, Pathophysiological Implications and Therapeutic Perspectives of Intercellular Mitochondrial Transfer.

Mitochondria are complex intracellular organelles traditionally identified as the powerhouses of eukaryotic cells due to their central role in bioenergetic metabolism. In recent decades, the growing interest in mitochondria research has revealed that these multifunctional organelles are more than just the cell powerhouses, playing many other key roles as signaling platforms that regulate cell metabolism, proliferation, death and immunological response. As key regulators, mitochondria, when dysfunctional, are involved in the pathogenesis of a wide range of metabolic, neurodegenerative, immune and neoplastic disorders. Far more recently, mitochondria attracted renewed attention from the scientific community for their ability of intercellular translocation that can involve whole mitochondria, mitochondrial genome or other mitochondrial components. The intercellular transport of mitochondria, defined as horizontal mitochondrial transfer, can occur in mammalian cells both in vitro and in vivo, and in physiological and pathological conditions. Mitochondrial transfer can provide an exogenous mitochondrial source, replenishing dysfunctional mitochondria, thereby improving mitochondrial faults or, as in in the case of tumor cells, changing their functional skills and response to chemotherapy. In this review, we will provide an overview of the state of the art of the up-to-date knowledge on intercellular trafficking of mitochondria by discussing its biological relevance, mode and mechanisms underlying the process and its involvement in different pathophysiological contexts, highlighting its therapeutic potential for diseases with mitochondrial dysfunction primarily involved in their pathogenesis.

Treatment with the Bacterial Toxin CNF1 Selectively Rescues Cognitive and Brain Mitochondrial Deficits in a Female Mouse Model of Rett Syndrome Carrying a MeCP2-Null Mutation.

Rett syndrome (RTT) is a rare neurological disorder caused by mutations in the X-linked MECP2 gene and a major cause of intellectual disability in females. No cure exists for RTT. We previously reported that the behavioural phenotype and brain mitochondria dysfunction are widely rescued by a single intracerebroventricular injection of the bacterial toxin CNF1 in a RTT mouse model carrying a truncating mutation of the MeCP2 gene (MeCP2-308 mice). Given the heterogeneity of MECP2 mutations in RTT patients, we tested the CNF1 therapeutic efficacy in a mouse model carrying a null mutation (MeCP2-Bird mice). CNF1 selectively rescued cognitive defects, without improving other RTT-related behavioural alterations, and restored brain mitochondrial respiratory chain complex activity in MeCP2-Bird mice. To shed light on the molecular mechanisms underlying the differential CNF1 effects on the behavioural phenotype, we compared treatment effects on relevant signalling cascades in the brain of the two RTT models. CNF1 provided a significant boost of the mTOR activation in MeCP2-308 hippocampus, which was not observed in the MeCP2-Bird model, possibly explaining the differential effects of CNF1. These results demonstrate that CNF1 efficacy depends on the mutation beared by MeCP2-mutated mice, stressing the need of testing potential therapeutic approaches across RTT models.

Epigallocatechin-3-Gallate Plus Omega-3 Restores the Mitochondrial Complex I and F0F1-ATP Synthase Activities in PBMCs of Young Children with Down Syndrome: A Pilot Study of Safety and Efficacy.

Down syndrome (DS) is a major genetic cause of intellectual disability. DS pathogenesis has not been fully elucidated, and no specific pharmacological therapy is available. DYRK1A overexpression, oxidative stress and mitochondrial dysfunction were described in trisomy 21. Epigallocatechin-3-gallate (EGCG) is a multimodal nutraceutical with antioxidant properties. EGCG inhibits DYRK1A overexpression and corrects DS mitochondrial dysfunction in vitro. The present study explores safety profiles in DS children aged 1-8 years treated with EGCG (10 mg/kg/die, suspended in omega-3, per os, in fasting conditions, for 6 months) and EGCG efficacy in restoring mitochondrial complex I and F0F1-ATP synthase (complex V) deficiency, assessed on PBMCs. The Griffiths Mental Developmental Scales-Extended Revised (GMDS-ER) was used for developmental profiling. Results show that decaffeinated EGCG (>90%) plus omega-3 is safe in DS children and effective in reverting the deficit of mitochondrial complex I and V activities. Decline of plasma folates was observed in 21% of EGCG-treated patients and should be carefully monitored. GMDS-ER scores did not show differences between the treated group compared to the DS control group. In conclusion, EGCG plus omega-3 can be safely administered under medical supervision in DS children aged 1-8 years to normalize mitochondria respiratory chain complex activities, while results on the improvement of developmental performance are still inconclusive.

Autism Spectrum Disorder from the Womb to Adulthood: Suggestions for a Paradigm Shift.

The wide spectrum of unique needs and strengths of Autism Spectrum Disorders (ASD) is a challenge for the worldwide healthcare system. With the plethora of information from research, a common thread is required to conceptualize an exhaustive pathogenetic paradigm. The epidemiological and clinical findings in ASD cannot be explained by the traditional linear genetic model, hence the need to move towards a more fluid conception, integrating genetics, environment, and epigenetics as a whole. The embryo-fetal period and the first two years of life (the so-called 'First 1000 Days') are the crucial time window for neurodevelopment. In particular, the interplay and the vicious loop between immune activation, gut dysbiosis, and mitochondrial impairment/oxidative stress significantly affects neurodevelopment during pregnancy and undermines the health of ASD people throughout life. Consequently, the most effective intervention in ASD is expected by primary prevention aimed at pregnancy and at early control of the main effector molecular pathways. We will reason here on a comprehensive and exhaustive pathogenetic paradigm in ASD, viewed not just as a theoretical issue, but as a tool to provide suggestions for effective preventive strategies and personalized, dynamic (from womb to adulthood), systemic, and interdisciplinary healthcare approach.

Impaired Brain Mitochondrial Bioenergetics in the Ts65Dn Mouse Model of Down Syndrome Is Restored by Neonatal Treatment with the Polyphenol 7,8-Dihydroxyflavone.

Down syndrome (DS), a major genetic cause of intellectual disability, is characterized by numerous neurodevelopmental defects. Previous in vitro studies highlighted a relationship between bioenergetic dysfunction and reduced neurogenesis in progenitor cells from the Ts65Dn mouse model of DS, suggesting a critical role of mitochondrial dysfunction in neurodevelopmental alterations in DS. Recent in vivo studies in Ts65Dn mice showed that neonatal supplementation (Days P3-P15) with the polyphenol 7,8-dihydroxyflavone (7,8-DHF) fully restored hippocampal neurogenesis. The current study was aimed to establish whether brain mitochondrial bioenergetic defects are already present in Ts65Dn pups and whether early treatment with 7,8-DHF positively impacts on mitochondrial function. In the brain and cerebellum of P3 and P15 Ts65Dn pups we found a strong impairment in the oxidative phosphorylation apparatus, resulting in a deficit in mitochondrial ATP production and ATP content. Administration of 7,8-DHF (dose: 5 mg/kg/day) during Days P3-P15 fully restored bioenergetic dysfunction in Ts65Dn mice, reduced the levels of oxygen radicals and reinstated the hippocampal levels of PGC-1α. No pharmacotherapy is available for DS. From current findings, 7,8-DHF emerges as a treatment with a good translational potential for improving mitochondrial bioenergetics and, thus, mitochondria-linked neurodevelopmental alterations in DS.

Targeting epigenetics in cancer: therapeutic potential of flavonoids.

Irrespective of sex and age, cancer is the leading cause of mortality around the globe. Therapeutic incompliance, unwanted effects, and economic burdens imparted by cancer treatments, are primary health challenges. The heritable features in gene expression that are propagated through cell division and contribute to cellular identity without a change in DNA sequence are considered epigenetic characteristics and agents that could interfere with these features and are regarded as potential therapeutic targets. The genetic modification accounts for the recurrence and uncontrolled changes in the physiology of cancer cells. This review focuses on plant-derived flavonoids as a therapeutic tool for cancer, attributed to their ability for epigenetic regulation of cancer pathogenesis. The epigenetic mechanisms of various classes of flavonoids including flavonols, flavones, isoflavones, flavanones, flavan-3-ols, and anthocyanidins, such as cyanidin, delphinidin, and pelargonidin, are discussed. The outstanding results of preclinical studies encourage researchers to design several clinical trials on various flavonoids to ascertain their clinical strength in the treatment of different cancers. The results of such studies will define the clinical fate of these agents in future.

Natural products, PGC-1 α , and Duchenne muscular dystrophy.

Peroxisome proliferator-activated receptor γ (PPARγ) is a transcriptional coactivator that binds to a diverse range of transcription factors. PPARγ coactivator 1 (PGC-1) coactivators possess an extensive range of biological effects in different tissues, and play a key part in the regulation of the oxidative metabolism, consequently modulating the production of reactive oxygen species, autophagy, and mitochondrial biogenesis. Owing to these findings, a large body of studies, aiming to establish the role of PGC-1 in the neuromuscular system, has shown that PGC-1 could be a promising target for therapies targeting neuromuscular diseases. Among these, some evidence has shown that various signaling pathways linked to PGC-1α are deregulated in muscular dystrophy, leading to a reduced capacity for mitochondrial oxidative phosphorylation and increased reactive oxygen species (ROS) production. In the light of these results, any intervention aimed at activating PGC-1 could contribute towards ameliorating the progression of muscular dystrophies. PGC-1α is influenced by different patho-physiological/pharmacological stimuli. Natural products have been reported to display modulatory effects on PPARγ activation with fewer side effects in comparison to synthetic drugs. Taken together, this review summarizes the current knowledge on Duchenne muscular dystrophy, focusing on the potential effects of natural compounds, acting as regulators of PGC-1α.

The Anti-Diabetic Drug Metformin Rescues Aberrant Mitochondrial Activity and Restrains Oxidative Stress in a Female Mouse Model of Rett Syndrome.

Metformin is the first-line therapy for diabetes, even in children, and a promising attractive candidate for drug repurposing. Mitochondria are emerging as crucial targets of metformin action both in the periphery and in the brain. The present study evaluated whether treatment with metformin may rescue brain mitochondrial alterations and contrast the increased oxidative stress in a validated mouse model of Rett syndrome (RTT), a rare neurologic disorder of monogenic origin characterized by severe behavioral and physiological symptoms. No cure for RTT is available. In fully symptomatic RTT mice (12 months old MeCP2-308 heterozygous female mice), systemic treatment with metformin (100 mg/kg ip for 10 days) normalized the reduced mitochondrial ATP production and ATP levels in the whole-brain, reduced brain oxidative damage, and rescued the increased production of reactive oxidizing species in blood. A 10-day long treatment with metformin also boosted pathways related to mitochondrial biogenesis and antioxidant defense in the brain of metformin-treated RTT mice. This treatment regimen did not improve general health status and motor dysfunction in RTT mice at an advanced stage of the disease. Present results provide evidence that systemic treatment with metformin may represent a novel, repurposable therapeutic strategy for RTT.

Aberrant mitochondrial bioenergetics in the cerebral cortex of the Fmr1 knockout mouse model of fragile X syndrome.

Impaired energy metabolism may play a role in the pathogenesis of neurodevelopmental disorders including fragile X syndrome (FXS). We checked brain energy status and some aspects of cell bioenergetics, namely the activity of key glycolytic enzymes, glycerol-3-phosphate shuttle and mitochondrial respiratory chain (MRC) complexes, in the cerebral cortex of the Fmr1 knockout (KO) mouse model of FXS. We found that, despite a hyperactivation of MRC complexes, adenosine triphosphate (ATP) production via mitochondrial oxidative phosphorylation (OXPHOS) is compromised, resulting in brain energy impairment in juvenile and late-adult Fmr1 KO mice. Thus, an altered mitochondrial energy metabolism may contribute to neurological impairment in FXS.

Brain-Immune Alterations and Mitochondrial Dysfunctions in a Mouse Model of Paediatric Autoimmune Disorder Associated with Streptococcus: Exacerbation by Chronic Psychosocial Stress.

Adverse psychosocial experiences have been shown to modulate individual responses to immune challenges and affect mitochondrial functions. The aim of this study was to investigate inflammation and immune responses as well as mitochondrial bioenergetics in an experimental model of Paediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcus (PANDAS). Starting in adolescence (postnatal day 28), male SJL/J mice were exposed to five injections (interspaced by two weeks) with Group-A beta-haemolytic streptococcus (GAS) homogenate. Mice were exposed to chronic psychosocial stress, in the form of protracted visual exposure to an aggressive conspecific, for four weeks. Our results indicate that psychosocial stress exacerbated individual response to GAS administrations whereby mice exposed to both treatments exhibited altered cytokine and immune-related enzyme expression in the hippocampus and hypothalamus. Additionally, they showed impaired mitochondrial respiratory chain complexes IV and V, and reduced adenosine triphosphate (ATP) production by mitochondria and ATP content. These brain abnormalities, observed in GAS-Stress mice, were associated with blunted titers of plasma corticosterone. Present data support the hypothesis that challenging environmental conditions, in terms of chronic psychosocial stress, may exacerbate the long-term consequences of exposure to GAS processes through the promotion of central immunomodulatory and oxidative stress.

Targeting BDNF signaling by natural products: Novel synaptic repair therapeutics for neurodegeneration and behavior disorders.

Neurodegenerative disorders like Alzheimer's disease, Huntington's disease, Parkinson's disease, spinocerebellar ataxias, amyotrophic lateral sclerosis, frontotemporal dementia to prion diseases, Friedreich's ataxia, hereditary spastic paraplegia and optic atrophy type 1, and behavior disorders like neuropsychiatric, hyperactivity and autism spectrum disorders are closely associated with neurobiological deficits. Brain derived neurotrophic factor (BDNF) is an extensively studied neurotrophin. BDNF is essential for neuronal genesis, differentiation, survival, growth, plasticity, synaptic viability and transmission. BDNF has emerged as a promising target for regulating synaptic activity and plasticity. An overview of effects and mechanisms of the natural products targeting BDNF is described. This review is an attempt to enumerate the effects of various natural products on BDNF as a novel therapeutic approach for neurodegenerative and neuropsychiatric disorders.

Novel therapeutic strategies for stroke: The role of autophagy.

Autophagy is an important biological mechanism involved in the regulation of numerous fundamental cellular processes that are mainly associated with cellular growth and differentiation. Autophagic pathways are vital for maintaining cellular homeostasis by enhancing the turnover of nonfunctional proteins and organelles. Neuronal cells, like other eukaryotic cells, are dependent on autophagy for neuroprotection in response to stress, but can also induce cell death in cerebral ischemia. Recent studies have demonstrated that autophagy may induce neuroprotection following acute brain injury, including ischemic stroke. However in some special circumstances, activation of autophagy can induce cell death, playing a deleterious role in the etiology and progression of ischemic stroke. Currently, there are no therapeutic options against stroke that demonstrate efficient neuroprotective abilities. In the present work, we will review the significance of autophagy in the context of ischemic stroke by first outlining its role in ischemic neuronal death. We will also highlight the potential therapeutic applications of pharmacological modulators of autophagy, including some naturally occurring polyphenolic compounds that can target this catabolic process. Our findings provide renewed insight on the mechanism of action of autophagy in stroke together with potential neuroprotective compounds, which may partially exert their function through enhancing mitochondrial function and attenuating damaging autophagic processes.

Down syndrome: Neurobiological alterations and therapeutic targets.

Down syndrome (DS) is a genetic disease that occurs due to an aneuploidy of human chromosome 21. Trisomy of chromosome 21 is a primary genetic cause of developmental abnormalities leading to cognitive and learning deficits. Impairments in GABAergic transmission, noradrenergic neuronal loss, anomalous glutamatergic transmission and N-methyl-d-aspartate receptor signalling, mitochondrial dysfunction, increased oxidative stress and inflammation, differentially expressed microRNAs, increased expression of crucial chromosome 21 genes, and DNA hyper-methylation and hyperactive homocysteine trans-sulfuration pathway, are common incongruities that have been reported in DS and might contribute to cognitive impairment and intellectual disability. This review provides an update on metabolic and neurobiological alterations in DS. It also provides an overview of the currently available pharmacological therapies that may influence and/or reverse these alterations in DS.