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1.
Int J Mol Sci ; 22(15)2021 Aug 02.
Article in English | MEDLINE | ID: covidwho-1736939

ABSTRACT

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.


Subject(s)
Metabolic Diseases/physiopathology , Mitochondria/physiology , Mitochondrial Dynamics , Neoplasms/physiopathology , Neurodegenerative Diseases/physiopathology , Animals , Humans , Metabolic Diseases/therapy , Neoplasms/therapy
2.
Brain Behav Immun ; 87: 34-39, 2020 07.
Article in English | MEDLINE | ID: covidwho-1719335

ABSTRACT

The coronavirus disease 19 (COVID-19) pandemic is a significant psychological stressor in addition to its tremendous impact on every facet of individuals' lives and organizations in virtually all social and economic sectors worldwide. Fear of illness and uncertainty about the future precipitate anxiety- and stress-related disorders, and several groups have rightfully called for the creation and dissemination of robust mental health screening and treatment programs for the general public and front-line healthcare workers. However, in addition to pandemic-associated psychological distress, the direct effects of the virus itself (several acute respiratory syndrome coronavirus; SARS-CoV-2), and the subsequent host immunologic response, on the human central nervous system (CNS) and related outcomes are unknown. We discuss currently available evidence of COVID-19 related neuropsychiatric sequelae while drawing parallels to past viral pandemic-related outcomes. Past pandemics have demonstrated that diverse types of neuropsychiatric symptoms, such as encephalopathy, mood changes, psychosis, neuromuscular dysfunction, or demyelinating processes, may accompany acute viral infection, or may follow infection by weeks, months, or longer in recovered patients. The potential mechanisms are also discussed, including viral and immunological underpinnings. Therefore, prospective neuropsychiatric monitoring of individuals exposed to SARS-CoV-2 at various points in the life course, as well as their neuroimmune status, are needed to fully understand the long-term impact of COVID-19, and to establish a framework for integrating psychoneuroimmunology into epidemiologic studies of pandemics.


Subject(s)
Coronavirus Infections/psychology , Cytokine Release Syndrome/psychology , Mental Disorders/psychology , Nervous System Diseases/psychology , Pneumonia, Viral/psychology , Acute Disease , Anxiety/etiology , Anxiety/immunology , Anxiety/psychology , Bacterial Translocation , Betacoronavirus , COVID-19 , Chronic Disease , Coronavirus Infections/complications , Coronavirus Infections/immunology , Coronavirus Infections/therapy , Cytokine Release Syndrome/immunology , Cytokine Release Syndrome/therapy , Demyelinating Diseases/etiology , Demyelinating Diseases/immunology , Demyelinating Diseases/physiopathology , Demyelinating Diseases/psychology , Depression/etiology , Depression/immunology , Depression/psychology , Humans , Immunologic Factors/adverse effects , Mental Disorders/etiology , Mental Disorders/immunology , Mental Health , Nervous System Diseases/etiology , Nervous System Diseases/immunology , Nervous System Diseases/physiopathology , Neurodegenerative Diseases/etiology , Neurodegenerative Diseases/immunology , Neurodegenerative Diseases/physiopathology , Neurodegenerative Diseases/psychology , Pandemics , Pneumonia, Viral/complications , Pneumonia, Viral/immunology , Pneumonia, Viral/therapy , Psychoneuroimmunology , Psychotic Disorders/etiology , Psychotic Disorders/immunology , Psychotic Disorders/psychology , Public Health , SARS-CoV-2 , Stress Disorders, Post-Traumatic/etiology , Stress Disorders, Post-Traumatic/immunology , Stress Disorders, Post-Traumatic/psychology
3.
Lancet Neurol ; 20(9): 753-761, 2021 09.
Article in English | MEDLINE | ID: covidwho-1599333

ABSTRACT

BACKGROUND: The mechanisms by which any upper respiratory virus, including SARS-CoV-2, impairs chemosensory function are not known. COVID-19 is frequently associated with olfactory dysfunction after viral infection, which provides a research opportunity to evaluate the natural course of this neurological finding. Clinical trials and prospective and histological studies of new-onset post-viral olfactory dysfunction have been limited by small sample sizes and a paucity of advanced neuroimaging data and neuropathological samples. Although data from neuropathological specimens are now available, neuroimaging of the olfactory system during the acute phase of infection is still rare due to infection control concerns and critical illness and represents a substantial gap in knowledge. RECENT DEVELOPMENTS: The active replication of SARS-CoV-2 within the brain parenchyma (ie, in neurons and glia) has not been proven. Nevertheless, post-viral olfactory dysfunction can be viewed as a focal neurological deficit in patients with COVID-19. Evidence is also sparse for a direct causal relation between SARS-CoV-2 infection and abnormal brain findings at autopsy, and for trans-synaptic spread of the virus from the olfactory epithelium to the olfactory bulb. Taken together, clinical, radiological, histological, ultrastructural, and molecular data implicate inflammation, with or without infection, in either the olfactory epithelium, the olfactory bulb, or both. This inflammation leads to persistent olfactory deficits in a subset of people who have recovered from COVID-19. Neuroimaging has revealed localised inflammation in intracranial olfactory structures. To date, histopathological, ultrastructural, and molecular evidence does not suggest that SARS-CoV-2 is an obligate neuropathogen. WHERE NEXT?: The prevalence of CNS and olfactory bulb pathosis in patients with COVID-19 is not known. We postulate that, in people who have recovered from COVID-19, a chronic, recrudescent, or permanent olfactory deficit could be prognostic for an increased likelihood of neurological sequelae or neurodegenerative disorders in the long term. An inflammatory stimulus from the nasal olfactory epithelium to the olfactory bulbs and connected brain regions might accelerate pathological processes and symptomatic progression of neurodegenerative disease. Persistent olfactory impairment with or without perceptual distortions (ie, parosmias or phantosmias) after SARS-CoV-2 infection could, therefore, serve as a marker to identify people with an increased long-term risk of neurological disease.


Subject(s)
COVID-19/complications , COVID-19/diagnostic imaging , Olfaction Disorders/diagnostic imaging , Olfaction Disorders/etiology , Olfactory Mucosa/diagnostic imaging , Brain/diagnostic imaging , Brain/physiopathology , Brain/virology , COVID-19/physiopathology , Humans , Neurodegenerative Diseases/diagnostic imaging , Neurodegenerative Diseases/etiology , Neurodegenerative Diseases/physiopathology , Olfaction Disorders/physiopathology , Olfaction Disorders/virology , Olfactory Mucosa/physiopathology , Olfactory Mucosa/virology , Prospective Studies , Smell/physiology
4.
J Clin Invest ; 131(19)2021 10 01.
Article in English | MEDLINE | ID: covidwho-1488299

ABSTRACT

Circadian disruption is pervasive and can occur at multiple organizational levels, contributing to poor health outcomes at individual and population levels. Evidence points to a bidirectional relationship, in that circadian disruption increases disease severity and many diseases can disrupt circadian rhythms. Importantly, circadian disruption can increase the risk for the expression and development of neurologic, psychiatric, cardiometabolic, and immune disorders. Thus, harnessing the rich findings from preclinical and translational research in circadian biology to enhance health via circadian-based approaches represents a unique opportunity for personalized/precision medicine and overall societal well-being. In this Review, we discuss the implications of circadian disruption for human health using a bench-to-bedside approach. Evidence from preclinical and translational science is applied to a clinical and population-based approach. Given the broad implications of circadian regulation for human health, this Review focuses its discussion on selected examples in neurologic, psychiatric, metabolic, cardiovascular, allergic, and immunologic disorders that highlight the interrelatedness between circadian disruption and human disease and the potential of circadian-based interventions, such as bright light therapy and exogenous melatonin, as well as chronotherapy to improve and/or modify disease outcomes.


Subject(s)
Circadian Rhythm/physiology , Biomarkers , Cardiovascular Diseases/physiopathology , Humans , Mental Disorders/physiopathology , Mental Disorders/therapy , Metabolic Diseases/physiopathology , Neurodegenerative Diseases/physiopathology , Neurodevelopmental Disorders/physiopathology , Public Health
5.
CNS Neurosci Ther ; 27(12): 1433-1436, 2021 12.
Article in English | MEDLINE | ID: covidwho-1462759

ABSTRACT

After almost a year of COVID-19, the chronic long-COVID syndrome has been recognized as an entity in 2021. The patients with the long-COVID are presenting with ominous neurological deficits that with time are becoming persistent and are causing disabilities in the affected individuals. The mechanisms underlying the neurological syndrome in long-COVID have remained obscure and need to be actively researched to find a resolution for the patients with long-COVID. Here, the factors like site of viral load, the differential immune response, neurodegenerative changes, and inflammation as possible causative factors are debated to understand and investigate the pathogenesis of neuro-COVID in long-COVID syndrome.


Subject(s)
COVID-19/complications , Nervous System Diseases/physiopathology , COVID-19/physiopathology , COVID-19/virology , Humans , Inflammation/etiology , Inflammation/physiopathology , Nervous System Diseases/etiology , Neurodegenerative Diseases/etiology , Neurodegenerative Diseases/physiopathology , Viral Load
6.
Brain Behav Immun ; 91: 740-755, 2021 01.
Article in English | MEDLINE | ID: covidwho-1064860

ABSTRACT

Central nervous system (CNS) innate immunity plays essential roles in infections, neurodegenerative diseases, and brain or spinal cord injuries. Astrocytes and microglia are the principal cells that mediate innate immunity in the CNS. Pattern recognition receptors (PRRs), expressed by astrocytes and microglia, sense pathogen-derived or endogenous ligands released by damaged cells and initiate the innate immune response. Toll-like receptors (TLRs) are a well-characterized family of PRRs. The contribution of microglial TLR signaling to CNS pathology has been extensively investigated. Even though astrocytes assume a wide variety of key functions, information about the role of astroglial TLRs in CNS disease and injuries is limited. Because astrocytes display heterogeneity and exhibit phenotypic plasticity depending on the effectors present in the local milieu, they can exert both detrimental and beneficial effects. TLRs are modulators of these paradoxical astroglial properties. The goal of the current review is to highlight the essential roles played by astroglial TLRs in CNS infections, injuries and diseases. We discuss the contribution of astroglial TLRs to host defense as well as the dissemination of viral and bacterial infections in the CNS. We examine the link between astroglial TLRs and the pathogenesis of neurodegenerative diseases and present evidence showing the pivotal influence of astroglial TLR signaling on sterile inflammation in CNS injury. Finally, we define the research questions and areas that warrant further investigations in the context of astrocytes, TLRs, and CNS dysfunction.


Subject(s)
Astrocytes/metabolism , Neurodegenerative Diseases/physiopathology , Toll-Like Receptors/physiology , Animals , Astrocytes/physiology , Brain/metabolism , Central Nervous System/immunology , Central Nervous System/metabolism , Central Nervous System Diseases/immunology , Central Nervous System Infections/pathology , Encephalitis/immunology , Humans , Immunity, Innate/physiology , Microglia/metabolism , Neurodegenerative Diseases/metabolism , Neurons/metabolism , Receptors, Pattern Recognition/immunology , Signal Transduction , Spinal Cord/pathology , Spinal Cord Injuries/pathology , Toll-Like Receptors/metabolism
7.
J Alzheimers Dis ; 79(3): 931-948, 2021.
Article in English | MEDLINE | ID: covidwho-1033235

ABSTRACT

Proinflammatory cytokines such as tumor necrosis factor (TNF), with its now appreciated key roles in neurophysiology as well as neuropathophysiology, are sufficiently well-documented to be useful tools for enquiry into the natural history of neurodegenerative diseases. We review the broader literature on TNF to rationalize why abruptly-acquired neurodegenerative states do not exhibit the remorseless clinical progression seen in those states with gradual onsets. We propose that the three typically non-worsening neurodegenerative syndromes, post-stroke, post-traumatic brain injury (TBI), and post cardiac arrest, usually become and remain static because of excess cerebral TNF induced by the initial dramatic peak keeping microglia chronically activated through an autocrine loop of microglial activation through excess cerebral TNF. The existence of this autocrine loop rationalizes post-damage repair with perispinal etanercept and proposes a treatment for cerebral aspects of COVID-19 chronicity. Another insufficiently considered aspect of cerebral proinflammatory cytokines is the fitness of the endogenous cerebral anti-TNF system provided by norepinephrine (NE), generated and distributed throughout the brain from the locus coeruleus (LC). We propose that an intact LC, and therefore an intact NE-mediated endogenous anti-cerebral TNF system, plus the DAMP (damage or danger-associated molecular pattern) input having diminished, is what allows post-stroke, post-TBI, and post cardiac arrest patients a strong long-term survival advantage over Alzheimer's disease and Parkinson's disease sufferers. In contrast, Alzheimer's disease and Parkinson's disease patients remorselessly worsen, being handicapped by sustained, accumulating, DAMP and PAMP (pathogen-associated molecular patterns) input, as well as loss of the LC-origin, NE-mediated, endogenous anti-cerebral TNF system. Adrenergic receptor agonists may counter this.


Subject(s)
Brain Injuries/physiopathology , Neurodegenerative Diseases/physiopathology , Stroke/physiopathology , Tumor Necrosis Factor-alpha/physiology , Alzheimer Disease/diagnosis , Alzheimer Disease/physiopathology , Alzheimer Disease/therapy , Anti-Inflammatory Agents, Non-Steroidal/therapeutic use , Brain/physiopathology , Brain Injuries/diagnosis , Brain Injuries/therapy , COVID-19/diagnosis , COVID-19/physiopathology , COVID-19/therapy , Disease Progression , Etanercept/therapeutic use , Heart Arrest/diagnosis , Heart Arrest/physiopathology , Heart Arrest/therapy , Humans , Locus Coeruleus/physiopathology , Neurodegenerative Diseases/diagnosis , Neurodegenerative Diseases/therapy , Norepinephrine/physiology , Parkinson Disease/diagnosis , Parkinson Disease/physiopathology , Parkinson Disease/therapy , Risk Factors , SARS-CoV-2 , Stroke/diagnosis , Stroke/therapy , Survivors , Tumor Necrosis Factor-alpha/antagonists & inhibitors
8.
Prog Neuropsychopharmacol Biol Psychiatry ; 109: 110230, 2021 07 13.
Article in English | MEDLINE | ID: covidwho-989032

ABSTRACT

Exacerbation of cognitive, motor and nonmotor symptoms have been described in critically ill COVID-19 patients, indicating that, like prior pandemics, neurodegenerative sequelae may mark the aftermath of this viral infection. Moreover, SARS-CoV-2, the causative agent of COVID-19 disease, was associated with hyperferritinemia and unfavorable prognosis in older individuals, suggesting virus-induced ferrosenescence. We have previously defined ferrosenescence as an iron-associated disruption of both the human genome and its repair mechanisms, leading to premature cellular senescence and neurodegeneration. As viruses replicate more efficiently in iron-rich senescent cells, they may have developed the ability to induce this phenotype in host tissues, predisposing to both immune dysfunction and neurodegenerative disorders. In this mini-review, we summarize what is known about the SARS-CoV-2-induced cellular senescence and iron dysmetabolism. We also take a closer look at immunotherapy with natural killer cells, angiotensin II receptor blockers ("sartans"), iron chelators and dipeptidyl peptidase 4 inhibitors ("gliptins") as adjunct treatments for both COVID-19 and its neurodegenerative complications.


Subject(s)
COVID-19/complications , COVID-19/physiopathology , Cellular Senescence , Iron Metabolism Disorders/etiology , Iron Metabolism Disorders/physiopathology , Neurodegenerative Diseases/etiology , Neurodegenerative Diseases/physiopathology , Humans , Iron/metabolism , Iron/physiology
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