Most cited article - PubMed ID 32225126
Emerging Roles of Blood-Borne Intact and Respiring Mitochondria as Bidirectional Mediators of Pro- and Anti-Inflammatory Processes
The bacterial origin of mitochondria has been a widely accepted as an event that occurred about 1.45 billion years ago and endowed cells with internal energy producing organelle. Thus, mitochondria have traditionally been viewed as subcellular organelle as any other - fully functionally dependent on the cell it is a part of. However, recent studies have given us evidence that mitochondria are more functionally independent than other organelles, as they can function outside the cells, engage in complex "social" interactions, and communicate with each other as well as other cellular components, bacteria and viruses. Furthermore, mitochondria move, assemble and organize upon sensing different environmental cues, using a process akin to bacterial quorum sensing. Therefore, taking all these lines of evidence into account we hypothesize that mitochondria need to be viewed and studied from a perspective of a more functionally independent entity. This view of mitochondria may lead to new insights into their biological function, and inform new strategies for treatment of disease associated with mitochondrial dysfunction.
- Keywords
- SARS-CoV-2, exosomes, independent mitochondria, mitochondria, sensory mitochondria, sentinel mitochondria, tunneling nanotubes, virus,
- MeSH
- Genes, Bacterial * MeSH
- Humans MeSH
- Mitochondria * MeSH
- Quorum Sensing MeSH
- Virion MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Review MeSH
The incidence of infections from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the etiologic agent for coronavirus disease 2019 (COVID-19), has dramatically escalated following the initial outbreak in China, in late 2019, resulting in a global pandemic with millions of deaths. Although the majority of infected patients survive, and the rapid advent and deployment of vaccines have afforded increased immunity against SARS-CoV-2, long-term sequelae of SARS-CoV-2 infection have become increasingly recognized. These include, but are not limited to, chronic pulmonary disease, cardiovascular disorders, and proinflammatory-associated neurological dysfunction that may lead to psychological and neurocognitive impairment. A major component of cognitive dysfunction is operationally categorized as "brain fog" which comprises difficulty concentrating, forgetfulness, confusion, depression, and fatigue. Multiple parameters associated with long-term neuropsychiatric sequelae of SARS-CoV-2 infection have been detailed in clinical studies. Empirically elucidated mechanisms associated with the neuropsychiatric manifestations of COVID-19 are by nature complex, but broad-based working models have focused on mitochondrial dysregulation, leading to systemic reductions of metabolic activity and cellular bioenergetics within the CNS structures. Multiple factors underlying the expression of brain fog may facilitate future pathogenic insults, leading to repetitive cycles of viral and bacterial propagation. Interestingly, diverse neurocognitive sequelae associated with COVID-19 are not dissimilar from those observed in other historical pandemics, thereby providing a broad and integrative perspective on potential common mechanisms of CNS dysfunction subsequent to viral infection. Poor mental health status may be reciprocally linked to compromised immune processes and enhanced susceptibility to infection by diverse pathogens. By extrapolation, we contend that COVID-19 may potentiate the severity of neurological/neurocognitive deficits in patients afflicted by well-studied neurodegenerative disorders, such as Alzheimer's disease and Parkinson's disease. Accordingly, the prevention, diagnosis, and management of sustained neuropsychiatric manifestations of COVID-19 are pivotal health care directives and provide a compelling rationale for careful monitoring of infected patients, as early mitigation efforts may reduce short- and long-term complications.
- Keywords
- COVID-19, Central nervous system, SARS-CoV-2, anxiety, brain fog, cognitive impairment, depression, long COVID, microglia, mitochondria, neuroinflammation, neuropsychiatric disease,
- MeSH
- Central Nervous System MeSH
- COVID-19 * complications MeSH
- Humans MeSH
- Neurodegenerative Diseases * MeSH
- Pandemics MeSH
- Disease Progression MeSH
- SARS-CoV-2 MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
Background: Mind-body medicine (MBM) focuses on improving our understanding of how the interactions between the brain, mind, body, and behavior can be used to promote health. In this narrative review, we present the basic principles of MBM, including the introduction of a rational framework for the implementation of MBM-based interventions. We also discuss the contributions of MBM to motivation and reward systems in the brain including those that may specifically involve the mitochondria. Results: MBM can be used to promote health in patients with chronic diseases, especially conditions identified as lifestyle-related. MBM builds on salutogenesis, which is a paradigm that focuses on health (as opposed to disease) determinants and the development of individual resilience and coherence factors as a means to reduce stress, decrease the burden of disease, and improve the quality of life. This approach involves several well-known principles of self-healing and self-care. MBM interventions typically include behavioral modification techniques in conjunction with cognitive work focused on stress regulation, exercise, relaxation, meditation, and nutrition. We suggest the use of the acronym "BERN" (Behavior, Exercise, Relaxation, and Nutrition) to summarize the operational framework of this approach. Discussion: Different BERN techniques act via shared autoregulatory central nervous system (CNS) reward and motivation circuitries. These systems rely on numerous neurobiological signaling pathways with overlapping effector molecules that converge, e.g., on nitric oxide (NO) as a common effector molecule. NO is critically coupled to reward physiology, stress reduction, and self-regulation as it modulates the responses of various mitochondrial, nuclear, and chromosomal processes within brain cells. NO has also been implicated in relevant outcomes (e.g., the placebo response). Conclusions: MBM interventions typically follow the BERN model and aim to strengthen health and resilience, and reduce stress. The mechanisms of action of these processes involve the CNS reward systems and correlate with placebo and self-healing pathways.
- Keywords
- behavioral medicine, integrative medicine, meditation, mitochondria, placebo, salutogenesis, self-healing, stress management,
- Publication type
- Journal Article MeSH
- Review MeSH
Mitochondria are complex endosymbionts that evolved from primordial purple nonsulfur bacteria. The incorporation of bacteria-derived mitochondria facilitates a more efficient and effective production of energy than what could be achieved based on previous processes alone. In this case, endosymbiosis has resulted in the seamless coupling of cytochrome c oxidase and F-ATPase to maximize energy production. However, this mechanism also results in the generation of reactive oxygen species (ROS), a phenomenon that can have both positive and negative ramifications on the host. Recent studies have revealed that neuropsychiatric disorders have a pro-inflammatory component in which ROS is capable of initiating damage and cognitive malfunction. Our current understanding of cognition suggests that it is the product of a neuronal network that consumes a substantial amount of energy. Thus, alterations or perturbations of mitochondrial function may alter not only brain energy supply and metabolite generation, but also thought processes and behavior. Mitochondrial abnormalities and oxidative stress have been implicated in several well-known psychiatric disorders, including schizophrenia (SCZ) and bipolar disorder (BPD). As cognition is highly energy-dependent, we propose that the neuronal pathways underlying maladaptive cognitive processing and psychiatric symptoms are most likely dependent on mitochondrial function, and thus involve brain energy translocation and the accumulation of the byproducts of oxidative stress. We also hypothesize that neuropsychiatric symptoms (e.g., disrupted emotional processing) may represent the vestiges of an ancient masked evolutionary response that can be used by both hosts and pathogens to promote self-repair and proliferation via parasitic and/or symbiotic pathways.
- Keywords
- HIV-1, SARS-CoV-2, bipolar disorder, depression, mitochondria, reactive nitrogen species, reactive oxygen species, schizophrenia,
- Publication type
- Journal Article MeSH
- Review MeSH
Mitochondrial DNA (mtDNA) heteroplasmy is the dynamically determined co-expression of wild type (WT) inherited polymorphisms and collective time-dependent somatic mutations within individual mtDNA genomes. The temporal expression and distribution of cell-specific and tissue-specific mtDNA heteroplasmy in healthy individuals may be functionally associated with intracellular mitochondrial signaling pathways and nuclear DNA gene expression. The maintenance of endogenously regulated tissue-specific copy numbers of heteroplasmic mtDNA may represent a sensitive biomarker of homeostasis of mitochondrial dynamics, metabolic integrity, and immune competence. Myeloid cells, monocytes, macrophages, and antigen-presenting dendritic cells undergo programmed changes in mitochondrial metabolism according to innate and adaptive immunological processes. In the central nervous system (CNS), the polarization of activated microglial cells is dependent on strategically programmed changes in mitochondrial function. Therefore, variations in heteroplasmic mtDNA copy numbers may have functional consequences in metabolically competent mitochondria in innate and adaptive immune processes involving the CNS. Recently, altered mitochondrial function has been demonstrated in the progression of coronavirus disease 2019 (COVID-19) due to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Accordingly, our review is organized to present convergent lines of empirical evidence that potentially link expression of mtDNA heteroplasmy by functionally interactive CNS cell types to the extent and severity of acute and chronic post-COVID-19 neurological disorders.
- Keywords
- COVID-19, Central nervous system, Gut microbiome, Immune response, Mitochondrial DNA, SARS-CoV-2,
- MeSH
- COVID-19 complications genetics immunology metabolism MeSH
- Heteroplasmy genetics MeSH
- Immunity MeSH
- Humans MeSH
- DNA, Mitochondrial genetics MeSH
- Mitochondria metabolism MeSH
- Nervous System Diseases complications genetics immunology metabolism MeSH
- Animals MeSH
- Check Tag
- Humans MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Review MeSH
- Names of Substances
- DNA, Mitochondrial MeSH
Persistent comorbidities occur in patients who initially recover from acute coronavirus disease 2019 (COVID-19) due to infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). 'Long COVID' involves the central nervous system (CNS), resulting in neuropsychiatric symptoms and signs, including cognitive impairment or 'brain fog' and chronic fatigue syndrome. There are similarities in these persistent complications between SARS-CoV-2 and the Ebola, Zika, and influenza A viruses. Normal CNS neuronal mitochondrial function requires high oxygen levels for oxidative phosphorylation and ATP production. Recent studies have shown that the SARS-CoV-2 virus can hijack mitochondrial function. Persistent changes in cognitive functioning have also been reported with other viral infections. SARS-CoV-2 infection may result in long-term effects on immune processes within the CNS by causing microglial dysfunction. This short opinion aims to discuss the hypothesis that the pathogenesis of long-term neuropsychiatric COVID-19 involves microglia, mitochondria, and persistent neuroinflammation.
- MeSH
- Central Nervous System pathology MeSH
- COVID-19 complications pathology MeSH
- Cognitive Dysfunction etiology pathology MeSH
- Humans MeSH
- Microglia pathology MeSH
- Mitochondria pathology MeSH
- Neurons pathology MeSH
- SARS-CoV-2 MeSH
- Inflammation pathology MeSH
- Check Tag
- Humans MeSH
- Publication type
- Editorial MeSH
Alterations in brain functioning, especially in regions associated with cognition, can result from infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and are predicted to result in various psychiatric diseases. Recent studies have shown that SARS-CoV-2 infection and coronavirus disease 2019 (COVID-19) can directly or indirectly affect the central nervous system (CNS). Therefore, diseases associated with sequelae of COVID-19, or 'long COVID', also include serious long-term mental and cognitive changes, including the condition recently termed 'brain fog'. Hypoxia in the microenvironment of select brain areas may benefit the reproductive capacity of the virus. It is possible that in areas of cerebral hypoxia, neuronal cell energy metabolism may become compromised after integration of the viral genome, resulting in mitochondrial dysfunction. Because of their need for constant high metabolism, cerebral tissues require an immediate and constant supply of oxygen. In hypoxic conditions, neurons with the highest oxygen demand become dysfunctional. The resulting cognitive impairment benefits viral spread, as infected individuals exhibit behaviors that reduce protection against infection. The effects of compromised mitochondrial function may also be an evolutionary advantage for SARS-CoV-2 in terms of host interaction. A high viral load in patients with COVID-19 that involves the CNS results in the compromise of neurons with high-level energy metabolism. Therefore, we propose that selective neuronal mitochondrial targeting in SARS-CoV-2 infection affects cognitive processes to induce 'brain fog' and results in behavioral changes that favor viral propagation. Cognitive changes associated with COVID-19 will have increasing significance for patient diagnosis, prognosis, and long-term care.
- MeSH
- COVID-19 complications metabolism physiopathology psychology transmission MeSH
- Energy Metabolism MeSH
- Cognitive Dysfunction metabolism physiopathology psychology MeSH
- Humans MeSH
- Microbial Viability MeSH
- Mitochondria metabolism MeSH
- Hypoxia, Brain metabolism physiopathology psychology MeSH
- Neurons metabolism MeSH
- Post-Acute COVID-19 Syndrome MeSH
- Virus Replication MeSH
- SARS-CoV-2 physiology MeSH
- Viral Load MeSH
- Health Behavior * MeSH
- Check Tag
- Humans MeSH
- Publication type
- Editorial MeSH