Implication of Aging Related Chronic Neuroinflammation on COVID-19 Pandemic

Targeting of neuroinflammation by glibenclamide in Covid-19: old weapon from arsenal

In coronavirus disease 2019 (Covid-19) era, neuroinflammation may develop due to neuronal tropism of severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) and/or associated immune activation, cytokine storm, and psychological stress. SARS-CoV-2 infection and linked cytokine storm may cause blood-brain barrier (BBB) injury through which activated immune cells and SARS-CoV-2 can pass into the brain causing activation of glial cells with subsequent neuroinflammation. Different therapeutic regimens were suggested to alleviate Covid-19-induced neuroinflammation. Since glibenclamide has anti-inflammatory and neuroprotective effects, it could be effective in mitigation of SARS-CoV-2 infection-induced neuroinflammation. Glibenclamide is a second-generation drug from the sulfonylurea family, which acts by inhibiting the adenosine triphosphate (ATP)-sensitive K channel in the regulatory subunit of type 1 sulfonylurea receptor (SUR-1) in pancreatic β cells. Glibenclamide reduces neuroinflammation and associated BBB injury by inhibiting the nod-like receptor pyrin 3 (NLRP3) inflammasome, oxidative stress, and microglial activation. Therefore, glibenclamide through inhibition of NLRP3 inflammasome, microglial activation, and oxidative stress may attenuate SARS-CoV-2-mediated neuroinflammation.

Immunosenescence and Aging: Neuroinflammation Is a Prominent Feature of Alzheimer's Disease and Is a Likely Contributor to Neurodegenerative Disease Pathogenesis

Alzheimer's disease (AD) is a chronic multifactorial and complex neuro-degenerative disorder characterized by memory impairment and the loss of cognitive ability, which is a problem affecting the elderly. The pathological intracellular accumulation of abnormally phosphorylated Tau proteins, forming neurofibrillary tangles, and extracellular amyloid-beta (Aβ) deposition, forming senile plaques, as well as neural disconnection, neural death and synaptic dysfunction in the brain, are hallmark pathologies that characterize AD. The prevalence of the disease continues to increase globally due to the increase in longevity, quality of life, and medical treatment for chronic diseases that decreases the mortality and enhance the survival of elderly. Medical awareness and the accurate diagnosis of the disease also contribute to the high prevalence observed globally. Unfortunately, no definitive treatment exists that can be used to modify the course of AD, and no available treatment is capable of mitigating the cognitive decline or reversing the pathology of the disease as of yet. A plethora of hypotheses, ranging from the cholinergic theory and dominant Aβ cascade hypothesis to the abnormally excessive phosphorylated Tau protein hypothesis, have been reported. Various explanations for the pathogenesis of AD, such as the abnormal excitation of the glutamate system and mitochondrial dysfunction, have also been suggested. Despite the continuous efforts to deliver significant benefits and an effective treatment for this distressing, globally attested aging illness, multipronged approaches and strategies for ameliorating the disease course based on knowledge of the underpinnings of the pathogenesis of AD are urgently needed. Immunosenescence is an immune deficit process that appears with age (inflammaging process) and encompasses the remodeling of the lymphoid organs, leading to alterations in the immune function and neuroinflammation during advanced aging, which is closely linked to the outgrowth of infections, autoimmune diseases, and malignant cancers. It is well known that long-standing inflammation negatively influences the brain over the course of a lifetime due to the senescence of the immune system. Herein, we aim to trace the role of the immune system in the pathogenesis of AD. Thus, we explore alternative avenues, such as neuroimmune involvement in the pathogenesis of AD. We determine the initial triggers of neuroinflammation, which is an early episode in the pre-symptomatic stages of AD and contributes to the advancement of the disease, and the underlying key mechanisms of brain damage that might aid in the development of therapeutic strategies that can be used to combat this devastating disease. In addition, we aim to outline the ways in which different aspects of the immune system, both in the brain and peripherally, behave and thus to contribute to AD.

Exploring the Paradox of COVID-19 in Neurological Complications with Emphasis on Parkinson’s and Alzheimer’s Disease

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a human coronavirus (HCoV) that has created a pandemic situation worldwide as COVID-19. This virus can invade human cells via angiotensin-converting enzyme 2 (ACE2) receptor-based mechanisms, affecting the human respiratory tract. However, several reports of neurological symptoms suggest a neuroinvasive development of coronavirus. SARS-CoV-2 can damage the brain via several routes, along with direct neural cell infection with the coronavirus. The chronic inflammatory reactions surge the brain with proinflammatory elements, damaging the neural cells, causing brain ischemia associated with other health issues. SARS-CoV-2 exhibited neuropsychiatric and neurological manifestations, including cognitive impairment, depression, dizziness, delirium, and disturbed sleep. These symptoms show nervous tissue damage that enhances the occurrence of neurodegenerative disorders and aids dementia. SARS-CoV-2 has been seen in brain necropsy and isolated from the cerebrospinal fluid of COVID-19 patients. The associated inflammatory reaction in some COVID-19 patients has increased proinflammatory cytokines, which have been investigated as a prognostic factor. Therefore, the immunogenic changes observed in Parkinson's and Alzheimer's patients include their pathogenetic role. Inflammatory events have been an important pathophysiological feature of neurodegenerative diseases (NDs) such as Parkinson's and Alzheimer's. The neuroinflammation observed in AD has exacerbated the Aβ burden and tau hyperphosphorylation. The resident microglia and other immune cells are responsible for the enhanced burden of Aβ and subsequently mediate tau phosphorylation and ultimately disease progression. Similarly, neuroinflammation also plays a key role in the progression of PD. Several studies have demonstrated an interplay between neuroinflammation and pathogenic mechanisms of PD. The dynamic proinflammation stage guides the accumulation of α-synuclein and neurodegenerative progression. Besides, few viruses may have a role as stimulators and generate a cross-autoimmune response for α-synuclein. Hence, neurological complications in patients suffering from COVID-19 cannot be ruled out. In this review article, our primary focus is on discussing the neuroinvasive effect of the SARS-CoV-2 virus, its impact on the blood-brain barrier, and ultimately its impact on the people affected with neurodegenerative disorders such as Parkinson's and Alzheimer's.

SARS-CoV-2 consequences for mental health: Neuroinflammatory pathways linking COVID-19 to anxiety and depression

The coronavirus disease 2019 (COVID-19) pandemic has been linked to an increased prevalence of mental health disorders, particularly anxiety and depression. Moreover, the COVID-19 pandemic has caused stress in people worldwide due to several factors, including fear of infection; social isolation; difficulty in adapting to new routines; lack of coping methods; high exposure to social media, misinformation, and fake reports; economic impact of the measures implemented to slow the contagion and concerns regarding the disease pathogenesis. COVID-19 patients have elevated levels of pro-inflammatory cytokines, such as interleukin (IL)-1β, IL-6, and tumor necrosis factor-α, and other inflammation-related factors. Furthermore, invasion of the central nervous system by the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) may potentially contribute to neuroinflammatory alterations in infected individuals. Neuroinflammation, a consequence of psychological stress due to the COVID-19 pandemic, may also play a role in the development of anxiety and depressive symptoms in the general population. Considering that neuroinflammation plays a significant role in the pathophysiology of depression and anxiety, this study investigated the effects of SARS-CoV-2 on mental health and focused on the impact of the COVID-19 pandemic on the neuroinflammatory pathways.

COVCOG 1: Factors Predicting Physical, Neurological and Cognitive Symptoms in Long COVID in a Community Sample. A First Publication From the COVID and Cognition Study

Since its first emergence in December 2019, coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has evolved into a global pandemic. Whilst often considered a respiratory disease, a large proportion of COVID-19 patients report neurological symptoms, and there is accumulating evidence for neural damage in some individuals, with recent studies suggesting loss of gray matter in multiple regions, particularly in the left hemisphere. There are a number of mechanisms by which COVID-19 infection may lead to neurological symptoms and structural and functional changes in the brain, and it is reasonable to expect that many of these may translate into cognitive problems. Indeed, cognitive problems are one of the most commonly reported symptoms in those experiencing "Long COVID"-the chronic illness following COVID-19 infection that affects between 10 and 25% of patients. The COVID and Cognition Study is a part cross-sectional, part longitudinal, study documenting and aiming to understand the cognitive problems in Long COVID. In this first paper from the study, we document the characteristics of our sample of 181 individuals who had experienced COVID-19 infection, and 185 who had not. We explore which factors may be predictive of ongoing symptoms and their severity, as well as conducting an in-depth analysis of symptom profiles. Finally, we explore which factors predict the presence and severity of cognitive symptoms, both throughout the ongoing illness and at the time of testing. The main finding from this first analysis is that that severity of initial illness is a significant predictor of the presence and severity of ongoing symptoms, and that some symptoms during the initial illness-particularly limb weakness-may be more common in those that have more severe ongoing symptoms. Symptom profiles can be well described in terms of 5 or 6 factors, reflecting the variety of this highly heterogenous condition experienced by the individual. Specifically, we found that neurological/psychiatric and fatigue/mixed symptoms during the initial illness, and that neurological, gastrointestinal, and cardiopulmonary/fatigue symptoms during the ongoing illness, predicted experience of cognitive symptoms.

SARS-CoV-2-Mediated Neuropathogenesis, Deterioration of Hippocampal Neurogenesis and Dementia

A significant portion of COVID-19 patients and survivors display marked clinical signs of neurocognitive impairments. SARS-CoV-2-mediated peripheral cytokine storm and its neurotropism appear to elicit the activation of glial cells in the brain proceeding to neuroinflammation. While adult neurogenesis has been identified as a key cellular basis of cognitive functions, neuroinflammation-induced aberrant neuroregenerative plasticity in the hippocampus has been implicated in progressive memory loss in ageing and brain disorders. Notably, recent histological studies of post-mortem human and experimental animal brains indicate that SARS-CoV-2 infection impairs neurogenic process in the hippocampus of the brain due to neuroinflammation. Considering the facts, this article describes the prominent neuropathogenic characteristics and neurocognitive impairments in COVID-19 and emphasizes a viewpoint that neuroinflammation-mediated deterioration of hippocampal neurogenesis could contribute to the onset and progression of dementia in COVID-19. Thus, it necessitates the unmet need for regenerative medicine for the effective management of neurocognitive deficits in COVID-19.

The microvascular hypothesis underlying neurologic manifestations of long COVID-19 and possible therapeutic strategies

With the ongoing distribution of the coronavirus disease (COVID) vaccines, the pandemic of our age is ending, leaving the world to deal with its well-documented aftereffects. Long COVID comprises a variety of symptoms, of which the neurological component prevails. The most permeating theory on the genesis of these symptoms builds upon the development of microvascular dysfunction similar to that seen in numerous vascular diseases such as diabetes. This can occur through the peripheral activation of angiotensin-converting enzyme 2 receptors, or through exacerbations of pro-inflammatory cytokines that can remain in circulation even after the infection diminishes. Several drugs have been identified to act on the neurovascular unit to promote repair, such as gliptins, and others. They also succeeded in improving neurologic outcome in diabetic patients. The repurposing of such drugs for treatment of long COVID-19 can possibly shorten the time to recovery of long COVID-19 syndrome.

Network Meta-analysis on the Changes of Amyloid Precursor Protein Expression Following SARS-CoV-2 Infection

SARS-CoV-2 infection begins with the attachment of its spike (S) protein to angiotensin-converting enzyme-2 (ACE2) followed by complex host immune responses with cardiovascular and neurological implications. Our meta-analyses used QIAGEN Ingenuity Pathway Analysis (IPA) and Knowledge Base (QKB) to investigate how the expression of amyloid precursor protein (APP) was modulated by attachment of SARS-CoV-2 S protein in the brain microvascular endothelial cells (BMVECs) and during COVID-19 in progress. Published 80 host response genes reported to be modulated in BMVECs following SARS-CoV-2 S protein binding were used to identify key canonical pathways and intermediate molecules mediating the regulation of APP production following the attachment of S protein to endothelial cells. This revealed that the attachment of SARS-CoV-2 S protein may inhibit APP expression in the BMVECs. Our results shed light on the molecular mechanisms by which SARS-CoV-2 infection may potentiate the incidence of stroke by inhibiting the production of APP in the BMVECs. We also analyzed molecules associated with COVID-19, which revealed six upstream regulators, TNF, IFNG, STAT1, IL1β, IL6, and STAT3. The upstream regulators mediate the increased production of APP via intermediators, with eleven regulated by all six upstream regulators. These COVID-19 upstream regulators increased APP expression with a statistically significant Z-score of 3.705 (p value = 0.000211). These findings have revealed molecular mechanisms by which COVID-19 disease may lead to long-term neurological manifestations resulting from the elevated APP expression in line with immune response in the host. Altogether, our study revealed two distinct scenarios which may have differential impact on APP expression.

The Anti-SARS-CoV-2 Antibody Response in a Centenarian Woman: A Case of Long-Term Memory?

SARS-CoV-2 is the virus responsible for the COVID-19 pandemic, causing respiratory syndrome and other manifestations. The clinical consequences of the SARS-CoV-2 infection are highly heterogeneous, ranging from asymptomatic and mild to severe and fatal conditions, with the highest mortality rate reached among elderly people. Such heterogeneity appears strongly influenced by the host immune response, which in turn is profoundly affected by aging. In fact, the occurrence of a low-grade inflammation and a decline in specific immune defense is generally reported in older people. Although the low ability of B cells to provide primary and secondary specific responses with a consequent increase in susceptibility to and severity of virus infections is generally described in elderly people, we would like to present here the particular case of a 100-year-old woman, who recovered well from COVID-19 and developed a long-term memory against SARS-CoV-2. Following the infection, the patient's blood was tested with both a classical ELISA and a specific Cell-ELISA addressed to measure the anti-spike S1 specific IgG released in plasma or produced in vitro by memory B cells, respectively. While showing negative on classical serological testing, the patient's blood was positive in Cell-ELISA up to 1 year after the infection. Our observation highlights a potential mechanism of B cell-dependent, long-term protection in response to SARS-CoV-2 infection, suggesting that in a case of successful aging, the absence of specific antibodies in serum does not necessarily mean the absence of immune memory.

COVID-19: a new emerging respiratory disease from the neurological perspective

Coronavirus disease 2019 (COVID-19) has become a challenging public health catastrophe worldwide. The newly emerged disease spread in almost all countries and infected 100 million persons worldwide. The infection is not limited to the respiratory system but involves various body systems and may lead to multiple organ failure. Tissue degenerative changes result from direct viral invasion, indirect consequences, or through an uncontrolled immune response. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spreads to the brain via hematogenous and neural routes accompanied with dysfunction of the blood-brain barrier. The involvement of the central nervous system is now suspected to be among the main causes of death. The present review discusses the historical background of coronaviruses, their role in previous and ongoing pandemics, the way they escape the immune system, why they are able to spread despite all undertaken measures, in addition to the neurological manifestations, long-term consequences of the disease, and various routes of viral introduction to the CNS.

Clinical Predictors of COVID-19 Mortality Among Patients in Intensive Care Units: A Retrospective Study

Objective

The ongoing pandemic of the coronavirus disease 2019 (COVID-19), which originated from Wuhan, China, has been identified to be caused by the novel beta coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). COVID-19 has been spreading rapidly worldwide within just a few months. Our aims were to analyze clinical and laboratory abnormalities in ICU patients with COVID-19, in order to define which predictors can distinguish between those who are at higher risk of developing fatal versus non-fatal forms of the disease.

Methods

A descriptive cross-sectional survey was used; demographics, comorbidities, symptoms, laboratory parameters at ICU admission, and clinical outcomes for the adult patients admitted to ICU were collected from five hospitals in Saudi Arabia.

Results

A total of 86 patients with COVID-19 admitted in ICU, 50 patients died, 23 recovered, and 13 were still admitted, with a mortality rate of 58.1%. Septic shock (OR (95% CI): 58.1 (5.97–7812.8), p < 0.001) and acute kidney injury (AKI) (OR (95% CI): 7.279 (1.191–65.43), p = 0.032) had a significant impact on mortality. Cox proportional-hazards regression analysis revealed that septic shock (HR (95% CI): 9.502 (2.958–30.524), p < 0.001) and neutrophil count (HR (95% CI): 1.053 (1.023–1.085), p < 0.001) were significant predictors for mortality.

Conclusion

Septic shock, AKI, and high neutrophil count were found to be predictive of death in these patients. Further studies are needed to aid efficient recognition and management of severe COVID-19 patients in our population. 

Neuroinflammation: A Signature or a Cause of Epilepsy?

Epilepsy can be both a primary pathology and a secondary effect of many neurological conditions. Many papers show that neuroinflammation is a product of epilepsy, and that in pathological conditions characterized by neuroinflammation, there is a higher probability to develop epilepsy. However, the bidirectional mechanism of the reciprocal interaction between epilepsy and neuroinflammation remains to be fully understood. Here, we attempt to explore and discuss the relationship between epilepsy and inflammation in some paradigmatic neurological and systemic disorders associated with epilepsy. In particular, we have chosen one representative form of epilepsy for each one of its actual known etiologies. A better understanding of the mechanistic link between neuroinflammation and epilepsy would be important to improve subject-based therapies, both for prophylaxis and for the treatment of epilepsy.

The impact of COVID-19 on diagnostic biomarkers in neuropsychiatric and neuroimmunological diseases: a review

Coronavirus disease 2019 (COVID-19) is an infectious respiratory disease, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Evidence-based emerging reports of neurological manifestations show that SARS-CoV-2 can attack the nervous system. However, little is known about the biomarkers in disease in neuropsychiatric and neuroimmunological disorders. One of the important keys in the management of COVID-19 is an accurate diagnosis. Biomarkers could provide valuable information in the early detection of disease etiology, diagnosis, further treatment, and prognosis. Moreover, ongoing investigations on hematologic, biochemical, and immunologic biomarkers in nonsevere, severe, or fatal forms of COVID-19 patients provide an urgent need for the identification of clinical and laboratory predictors. In addition, several cytokines acting through mechanisms to emerge immune response against SARS-CoV-2 infection are known to play a major role in neuroinflammation. Considering the neuroinvasive potential of SARS-CoV-2, which can be capable of triggering a cytokine storm, the current evidence on inflammation in psychiatry and neurodegenerative by emerging neuroinflammation is discussed in this review. We also highlighted the hematologic, biochemical, and immunologic biomarkers in COVID-19 diagnosis. COVID-19 prognostic biomarkers in patients with neuropsychiatric and neuroimmunological diseases are also explained.

Involvement of Interleukin-1 Receptor-Associated Kinase 4 and Interferon Regulatory Factor 5 in the Immunopathogenesis of SARS-CoV-2 Infection: Implications for the Treatment of COVID-19

Interleukin-1 receptor-associated kinase 4 (IRAK4) and interferon regulatory factor 5 (IRF5) lie sequentially on a signaling pathway activated by ligands of the IL-1 receptor and/or multiple TLRs located either on plasma or endosomal membranes. Activated IRF5, in conjunction with other synergistic transcription factors, notably NF-κB, is crucially required for the production of proinflammatory cytokines in the innate immune response to microbial infection. The IRAK4-IRF5 axis could therefore have a major role in the induction of the signature cytokines and chemokines of the hyperinflammatory state associated with severe morbidity and mortality in COVID-19. Here a case is made for considering IRAK4 or IRF5 inhibitors as potential therapies for the "cytokine storm" of COVID-19.

Neurologic and Neuroscientific Evidence in Aged COVID-19 Patients

The COVID-19 pandemic continues to prevail as a catastrophic wave infecting over 111 million people globally, claiming 2. 4 million lives to date. Aged individuals are particularly vulnerable to this disease due to their fraility, immune dysfunction, and higher rates of medical comorbidities, among other causes. Apart from the primary respiratory illness, this virus is known to cause multi-organ dysfunction including renal, cardiac, and neurologic injuries, particularly in the critically-ill cohorts. Elderly patients 65 years of age or older are known to have more severe systemic disease and higher rates of neurologic complications. Morbidity and mortality is very high in the elderly population with 6–930 times higher likelihood of death compared to younger cohorts, with the highest risk in elderly patients ≥85 years and especially those with medical comorbidities such as hypertension, diabetes, heart disease, and underlying respiratory illness. Commonly reported neurologic dysfunctions of COVID-19 include headache, fatigue, dizziness, and confusion. Elderly patients may manifest atypical presentations like fall or postural instability. Other important neurologic dysfunctions in the elderly include cerebrovascular diseases, cognitive impairment, and neuropsychiatric illnesses. Elderly patients with preexisting neurologic diseases are susceptibility to severe COVID-19 infection and higher rates of mortality. Treatment of neurologic dysfunction of COVID-19 is based on existing practice standards of specific neurologic condition in conjunction with systemic treatment of the viral illness. The physical, emotional, psychologic, and financial implications of COVID-19 pandemic have been severe. Long-term data are still needed to understand the lasting effects of this devastating pandemic.

A vicious circle between oxidative stress and cytokine storm in acute respiratory distress syndrome pathogenesis at COVID-19 infection

In early December 2019, the pandemic of coronavirus disease 2019 (COVID-19) began in Wuhan City, Hubei Province, China. Since then, it has propagated rapidly and turned into a major global crisis due to the high virus spreading. Acute respiratory distress syndrome (ARDS) is considered as a defining cause of the death cases. Cytokine storm and oxidative stress are the main players of ARDS development during respiratory virus infections. In this review, we discussed molecular mechanisms of a fatal vicious circle between oxidative stress and cytokine storm during COVID-19 infection. We also described how aging can inflame the vicious circle. Keywords: acute respiratory distress syndrome (ARDS), COVID-19, cytokine storm, oxidative stress

Antioxidant Properties of Second-Generation Antipsychotics: Focus on Microglia

Recent studies suggest a primary role of oxidative stress in an early phase of the pathogenesis of schizophrenia and a strong neurobiological link has been found between dopaminergic system dysfunction, microglia overactivation, and oxidative stress. Different risk factors for schizophrenia increase oxidative stress phenomena raising the risk of developing psychosis. Oxidative stress induced by first-generation antipsychotics such as haloperidol significantly contributes to the development of extrapyramidal side effects. Haloperidol also exerts neurotoxic effects by decreasing antioxidant enzyme levels then worsening pro-oxidant events. Opposite to haloperidol, second-generation antipsychotics (or atypical antipsychotics) such as risperidone, clozapine, and olanzapine exert a strong antioxidant activity in experimental models of schizophrenia by rescuing the antioxidant system, with an increase in superoxide dismutase and glutathione (GSH) serum levels. Second-generation antipsychotics also improve the antioxidant status and reduce lipid peroxidation in schizophrenic patients. Interestingly, second-generation antipsychotics, such as risperidone, paliperidone, and in particular clozapine, reduce oxidative stress induced by microglia overactivation, decreasing the production of microglia-derived free radicals, finally protecting neurons against microglia-induced oxidative stress. Further, long-term clinical studies are needed to better understand the link between oxidative stress and the clinical response to antipsychotic drugs and the therapeutic potential of antioxidants to increase the response to antipsychotics.