The hidden role of NLRP3 inflammasome in obesity-related COVID-19 exacerbations: Lessons for drug repurposing

Neuro-inflammatory pathways in COVID-19-induced central nervous system injury: Implications for prevention and treatment strategies

This review explores the neuroinflammatory pathways underlying COVID-19-induced central nervous system (CNS) injury, with a focus on mechanisms of brain damage and strategies for prevention. A comprehensive literature review was conducted to summarize current knowledge on the pathways by which SARS-CoV-2 reaches the brain, the neuroinflammatory responses triggered by viral infection, neurological symptoms and long COVID. Results: We discuss the mechanisms of neuroinflammation in COVID-19, including blood-brain barrier disruption, cytokine storm, microglial activation, and peripheral immune cell infiltration. Additionally, we highlight potential strategies for preventing CNS injury, including pharmacological interventions, immunomodulatory therapies, and lifestyle modifications. Conclusively, Understanding the neuroinflammatory pathways in COVID-19-induced CNS injury is crucial for developing effective prevention and treatment strategies to protect brain health during and after viral infection.

Drug repositioning in the COVID-19 pandemic: fundamentals, synthetic routes, and overview of clinical studies

INTRODUCTION

Drug repositioning is a strategy to identify a new therapeutic indication for molecules that have been approved for other conditions, aiming to speed up the traditional drug development process and reduce its costs. The high prevalence and incidence of coronavirus disease 2019 (COVID-19) underline the importance of searching for a safe and effective treatment for the disease, and drug repositioning is the most rational strategy to achieve this goal in a short period of time. Another advantage of repositioning is the fact that these compounds already have established synthetic routes, which facilitates their production at the industrial level. However, the hope for treatment cannot allow the indiscriminate use of medicines without a scientific basis.

RESULTS

The main small molecules in clinical trials being studied to be potentially repositioned to treat COVID-19 are chloroquine, hydroxychloroquine, ivermectin, favipiravir, colchicine, remdesivir, dexamethasone, nitazoxanide, azithromycin, camostat, methylprednisolone, and baricitinib. In the context of clinical tests, in general, they were carried out under the supervision of large consortiums with a methodology based on and recognized in the scientific community, factors that ensure the reliability of the data collected. From the synthetic perspective, compounds with less structural complexity have more simplified synthetic routes. Stereochemical complexity still represents the major challenge in the preparation of dexamethasone, ivermectin, and azithromycin, for instance.

CONCLUSION

Remdesivir and baricitinib were approved for the treatment of hospitalized patients with severe COVID-19. Dexamethasone and methylprednisolone should be used with caution. Hydroxychloroquine, chloroquine, ivermectin, and azithromycin are ineffective for the treatment of the disease, and the other compounds presented uncertain results. Preclinical and clinical studies should not be analyzed alone, and their methodology's accuracy should also be considered. Regulatory agencies are responsible for analyzing the efficacy and safety of a treatment and must be respected as the competent authorities for this decision, avoiding the indiscriminate use of medicines.

Alcohol use disorder as a potential risk factor for COVID-19 severity: A narrative review

In Dec. 2019-January 2020, a pneumonia illness originating in Wuhan, China, designated as coronavirus disease 2019 (COVID-19) was shown to be caused by a novel RNA coronavirus designated as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). People with advanced age, male sex, and/or underlying health conditions (obesity, type 2 diabetes, cardiovascular disease, hypertension, chronic kidney disease, and chronic lung disease) are especially vulnerable to severe COVID-19 symptoms and death. These risk factors impact the immune system and are also associated with poor health, chronic illness, and shortened longevity. However, a large percent of patients without these known risk factors also develops severe COVID-19 disease that can result in death. Thus, there must exist risk factors that promote exaggerated inflammatory and immune response to the SARS-CoV-2 virus leading to death. One such risk factor may be alcohol misuse and alcohol use disorder because these can exacerbate viral lung infections like SARS, influenza, and pneumonia. Thus, it is highly plausible that alcohol misuse is a risk factor for either increased infection rate when individuals are exposed to SARS-CoV-2 virus and/or more severe COVID-19 in infected patients. Alcohol use is a well-known risk factor for lung diseases and ARDS in SARS patients. We propose that alcohol has three key pathogenic elements in common with other COVID-19 severity risk factors: namely, inflammatory microbiota dysbiosis, leaky gut, and systemic activation of the NLRP3 inflammasome. We also propose that these three elements represent targets for therapy for severe COVID-19.

Innate Immune Response and Inflammasome Activation During SARS-CoV-2 Infection

The novel coronavirus SARS-CoV-2, responsible for the COVID-19 outbreak, has become a pandemic threatening millions of lives worldwide. Recently, several vaccine candidates and drugs have shown promising effects in preventing or treating COVID-19, but due to the development of mutant strains through rapid viral evolution, urgent investigations are warranted in order to develop preventive measures and further improve current vaccine candidates. Positive-sense-single-stranded RNA viruses comprise many (re)emerging human pathogens that pose a public health problem. Our innate immune system and, in particular, the interferon response form an important first line of defense against these viruses. Flexibility in the genome aids the virus to develop multiple strategies to evade the innate immune response and efficiently promotes their replication and infective capacity. This review will focus on the innate immune response to SARS-CoV-2 infection and the virus' evasion of the innate immune system by escaping recognition or inhibiting the production of an antiviral state. Since interferons have been implicated in inflammatory diseases and immunopathology along with their protective role in infection, antagonizing the immune response may have an ambiguous effect on the clinical outcome of the viral disease. This pathology is characterized by intense, rapid stimulation of the innate immune response that triggers activation of the Nod-like receptor family, pyrin-domain-containing 3 (NLRP3) inflammasome pathway, and release of its products including the pro-inflammatory cytokines IL-6, IL-18, and IL-1β. This predictive view may aid in designing an immune intervention or preventive vaccine for COVID-19 in the near future.

Obesity and Coronavirus Disease 2019

The coronavirus disease 2019 (COVID-19) pandemic has brought severe challenges to global public health. Many studies have shown that obesity plays a vital role in the occurrence and development of COVID-19. Obesity exacerbates COVID-19, leading to increased intensive care unit hospitalization rate, high demand for invasive mechanical ventilation, and high mortality. The mechanisms of interaction between obesity and COVID-19 involve inflammation, immune response, changes in pulmonary dynamics, disruptions of receptor ligands, and dysfunction of endothelial cells. Therefore, for obese patients with COVID-19, the degree of obesity and related comorbidities should be evaluated. Treatment methods such as administration of anticoagulants and anti-inflammatory drugs like glucocorticoids and airway management should be actively initiated. We should also pay attention to long-term prognosis and vaccine immunity and actively address the physical and psychological problems caused by longterm staying-at-home during the pandemic. The present study summarized the research to investigate the role of obesity in the incidence and progression of COVID-19 and the psychosocial impact and treatment options for obese patients with COVID-19, to guide the understanding and management of the disease.

Targeting autophagy regulation in NLRP3 inflammasome-mediated lung inflammation in COVID-19

Coronavirus disease 2019 (COVID-19) is an infectious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Emerging evidence indicates that the NOD-, LRR- and pyrin domain-containing protein 3 (NLRP3) inflammasome is activated, which results in a cytokine storm at the late stage of COVID-19. Autophagy regulation is involved in the infection and replication of SARS-CoV-2 at the early stage and the inhibition of NLRP3 inflammasome-mediated lung inflammation at the late stage of COVID-19. Here, we discuss the autophagy regulation at different stages of COVID-19. Specifically, we highlight the therapeutic potential of autophagy activators in COVID-19 by inhibiting the NLRP3 inflammasome, thereby avoiding the cytokine storm. We hope this review provides enlightenment for the use of autophagy activators targeting the inhibition of the NLRP3 inflammasome, specifically the combinational therapy of autophagy modulators with the inhibitors of the NLRP3 inflammasome, antiviral drugs, or anti-inflammatory drugs in the fight against COVID-19.

Molecular Mimicry, Hyperactive Immune System, And SARS-COV-2 Are Three Prerequisites of the Autoimmune Disease Triangle Following COVID-19 Infection

SARS-CoV-2 infection can produce a variety of clinical manifestations, which are either directly related to viral tissue damage or indirectly induced by the antiviral immune response. Molecular mimicry enables this virus to undermine self-tolerance in a host's immune system also immune system's attempts to eliminate SARS-COV-2 may trigger autoimmunity by hyper-activating the innate and adaptive immune systems. Auto immune diseases include Systemic lupus erythematosus, autoimmune thyroid diseases, Guillain‐Barre syndrome, Immune thrombocytopenic purpura, and the detection of autoantibodies are the cues to the discovery of the potential of COVID‐19 in inducing autoimmunity. As COVID-19 and autoimmune diseases share a common pathogenesis, autoimmune drugs may be an effective treatment option. Susceptible patients must be monitored for autoimmune symptoms after contracting CVID-19. In light of the SARS-COV-2 virus' ability to induce autoimmunity in susceptible patients, will the various COVID-19 vaccines that are the only way to end the pandemic induce autoimmunity?

Shared Inflammatory Pathology of Stroke and COVID-19

Though COVID-19 is primarily characterized by symptoms in the periphery, it can also affect the central nervous system (CNS). This has been established by the association between stroke and COVID-19. However, the molecular mechanisms that cause stroke related to a COVID-19 infection have not been fully explored. More specifically, stroke and COVID-19 exhibit an overlap of molecular mechanisms. These similarities provide a way to better understand COVID-19 related stroke. We propose here that peripheral macrophages upregulate inflammatory proteins such as matrix metalloproteinases (MMPs) in response to SARS-CoV-2 infection. These inflammatory molecules and the SARS-CoV-2 virus have multiple negative effects related to endothelial dysfunction that results in the disruption of the blood-brain barrier (BBB). Finally, we discuss how the endothelial blood-brain barrier injury alters central nervous system function by leading to astrocyte dysfunction and inflammasome activation. Our goal is to elucidate such inflammatory pathways, which could provide insight into therapies to combat the negative neurological effects of COVID-19.

PM2.5 exposure inducing ATP alteration links with NLRP3 inflammasome activation

Fine particulate matter (PM_2.5) has been the primary air pollutant and the fourth leading risk factor for disease and death in the world. Exposure to PM_2.5 is related to activation of the NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome, but the mechanism of PM_2.5 affecting the NLRP3 inflammasome is still unclear. Previous studies have shown that PM_2.5 can cause alterations in adenosine triphosphate (ATP), and an increase in extracellular ATP and a decrease in intracellular ATP can trigger the activation process of the NLRP3 inflammasome. Therefore, we emphasize that ATP changes may be the central link and key mechanism of PM_2.5 exposure that activates the NLRP3 inflammasome. This review briefly elucidates and summarizes how PM_2.5 acts on ATP and subsequently further impacts the NLRP3 inflammasome. Investigation of ATP changes due to exposure to PM_2.5 may be essential to regulate NLRP3 inflammasome activation and treat inflammation-related diseases such as coronavirus disease 2019 (COVID-19).

COVID-19-induced immune thrombocytopenic purpura; Immunopathogenesis and clinical implications

Following the outbreak of the COVID-19 pandemic, millions of people around the world have been affected with SARS-CoV-2 infection. In addition to the typical symptoms, thrombotic events, lymphopenia, and thrombocytopenia have been reported in COVID-19 patients. Immune thrombocytopenic purpura (ITP) is one of the thrombotic events that occur in some COVID-19 patients. Hyperinflammation, cytokine storms, and immune dysregulation in some patients are the cause to the main COVID-19 complications such as ALI (acute lung injury), acute respiratory distress syndrome (ARDS), and multiple organ failure. Disruption in the differentiation of T-cells, enhanced differentiation of Th17 and Th1, cell death (pyroptosis), hyper-inflammation and dysfunction of inflammatory neutrophils and macrophages, and hyperactivity of NLRP3-inflammasome are among the important factors that may be the cause to COVID-19-induced ITP. This study aimed to give an overview of the findings on the immunopathogenesis of ITP and COVID-19-induced ITP. Further studies are required to better understand the exact immunopathogenesis and effective treatments for ITP, especially in inflammatory disorders.

Tranilast as an Adjunctive Therapy in Hospitalized Patients with Severe COVID- 19: A Randomized Controlled Trial

Background

Tranilast is a potential NLRP3 inflammasome inhibitor that may relieve progressive inflammation due to COVID-19.

Aim of the study

To evaluate the therapeutic effects of Tranilast in combination with antiviral drugs in non-ICU-admitted hospitalized patients with COVID-19.

Methods

This study was an open-label clinical trial that included 72 hospitals admitted patients with severe COVID-19 at Razi Hospital, Ahvaz, Iran, from July 2020–August 2020. These patients were randomly assigned in a 1:1 ratio to control (30) and intervention groups (30). Patients in the control group received antiviral therapy, while patients in the intervention group received Tranilast (300 mg daily) in addition to the antiviral drugs for Seven days. The collected data, including the expression of inflammatory cytokine, laboratory tests, and clinical findings, was used for intragroup comparisons.

Results

The intervention group showed significantly lower levels of NLR (p = 0.001), q-CRP (p = 0.002), IL-1 (p = 0.001), TNF (p = 0.001), and LDH (p = 0.046) in comparison with the control group. The effect of intervention was significant in increasing the o2 saturation (F = 7.72, p = 0.007). Long hospitalization (four days or above) was 36.6% in the Tranilast and 66.6% in the control group (RR = 0.58; 95% CI: 0.38–1.06, p = 0.045). In the Tranilst and control groups, one and four deaths or hospitalization in ICU were observed respectively (RR = 0.31; 95% CI: 0.03–2.88, p = 0.20).

Conclusions

Tranilast might be used as an effective and safe adjuvant therapy and enhance the antiviral therapy's efficacy for managing patients with COVID-19.

The effect of colchicine on mortality outcome and duration of hospital stay in patients with COVID-19: A meta-analysis of randomized trials

BACKGROUND

Overactivation of the NLR family pyrin domain containing 3 (NLRP3) inflammasome can lead to severe illness in patients with coronavirus disease-2019 (COVID-19). The NLRP3 inhibitor, colchicine, therefore, appears to be promising for the treatment of COVID-19.

AIMS

We aimed to perform a meta-analysis of randomized trials investigating the effect of colchicine in patients with COVID-19.

MATERIALS & METHODS

We systematically searched electronic databases and clinical trial registries (up to October 17, 2021) for eligible studies. The outcomes of interest were all-cause mortality and duration of hospital stay. Meta-analysis with the random-effects model was used to estimate the pooled odds ratio (OR) of mortality and 95% confidence interval (CI). The pooled standardized mean difference of duration of hospital stay with 95% CI between colchicine users and non-colchicine users was estimated using Cohen's d index.

RESULTS

The meta-analyses revealed no significant difference in the odds of mortality (pooled OR = 0.76; 95% CI: 0.53-1.07), but a significant reduction in the duration of hospital stay with the use of colchicine (pooled standardized mean difference = -0.59; 95% CI: -1.06 to -0.13).

DISCUSSION AND CONCLUSION

The ability of colchicine to reduce the length of stay in hospitalized patients with COVID-19 is consistent with its potential to prevent clinical deterioration via inhibition of NLRP3 inflammasome. Nevertheless, such beneficial effects of colchicine did not translate into mortality benefits in patients with COVID-19.

Causal Biological Network Model for Inflammasome Signaling Applied for Interpreting Transcriptomic Changes in Various Inflammatory States

Virtually any stressor that alters the cellular homeostatic state may result in an inflammatory response. As a critical component of innate immunity, inflammasomes play a prominent role in the inflammatory response. The information on inflammasome biology is rapidly growing, thus creating the need for structuring it into a model that can help visualize and enhance the understanding of underlying biological processes. Causal biological network (CBN) models provide predictive power for novel disease mechanisms and treatment outcomes. We assembled the available literature information on inflammasome activation into the CBN model and scored it with publicly available transcriptomic datasets that address viral infection of the lungs, osteo- and rheumatoid arthritis, psoriasis, and aging. The scoring inferred pathway activation leading to NLRP3 inflammasome activation in these diverse conditions, demonstrating that the CBN model provides a platform for interpreting transcriptomic data in the context of inflammasome activation.

Obesity and Its Impact on Adverse In-Hospital Outcomes in Hospitalized Patients With COVID-19

BACKGROUND

An increasing level of evidence suggests that obesity not only is a major risk factor for cardiovascular diseases (CVDs) but also has adverse outcomes during COVID-19 infection.

METHODS

We used the German nationwide inpatient sample to analyze all hospitalized patients with confirmed COVID-19 diagnosis in Germany from January to December 2020 and stratified them for diagnosed obesity. Obesity was defined as body mass index ≥30 kg/m² according to the WHO. The impact of obesity on in-hospital case fatality and adverse in-hospital events comprising major adverse cardiovascular and cerebrovascular events (MACCE), acute respiratory distress syndrome (ARDS), venous thromboembolism (VTE), and others was analyzed.

RESULTS

We analyzed data of 176,137 hospitalizations of patients with confirmed COVID-19 infection; among them, 9,383 (5.3%) had an additional obesity diagnosis. Although COVID-19 patients without obesity were older (72.0 [interquartile range (IQR) 56.0/82.0] vs. 66.0 [54.0/76.0] years, p < 0.001), the CVD profile was less favorable in obese COVID-19 patients (Charlson comorbidity index 4.44 ± 3.01 vs. 4.08 ± 2.92, p < 0.001). Obesity was independently associated with increased in-hospital case fatality (OR 1.203 [95% CI 1.131-1.279], p < 0.001) and MACCE (OR 1.168 [95% CI 1.101-1.239], p < 0.001), ARDS (OR 2.605 [95% CI 2.449-2.772], p < 0.001), and VTE (OR 1.780 [95% CI 1.605-1.973], p < 0.001) and also associated with increased necessity of treatment on intensive care unit (OR 2.201 [95% CI 2.097-2.310], p < 0.001), mechanical ventilation (OR 2.277 [95% CI 2.140-2.422], p < 0.001), and extracorporeal membrane oxygenation (OR 3.485 [95% CI 3.023-4.017], p < 0.001).

CONCLUSIONS

Obesity independently affected case fatality, MACCE, ARDS development, VTE, and other adverse in-hospital events in patients with COVID-19 infection. Obesity should be taken into account regarding COVID-19 prevention strategies, risk stratification, and adequate healthcare planning. Maintaining a healthy weight is important not only to prevent cardiometabolic diseases but also for better individual outcomes during COVID-19 infection.

Specific inhibition of the NLRP3 inflammasome suppresses immune overactivation and alleviates COVID-19 like pathology in mice

Background

The Coronavirus Disease 2019 (COVID-19) pandemic has been a great threat to global public health since 2020. Although the advance on vaccine development has been largely achieved, a strategy to alleviate immune overactivation in severe COVID-19 patients is still needed. The NLRP3 inflammasome is activated upon SARS-CoV-2 infection and associated with COVID-19 severity. However, the processes by which the NLRP3 inflammasome is involved in COVID-19 disease remain unclear.

Methods

We infected THP-1 derived macrophages, NLRP3 knockout mice, and human ACE2 transgenic mice with live SARS-CoV-2 in Biosafety Level 3 (BSL-3) laboratory. We performed quantitative real-time PCR for targeted viral or host genes from SARS-CoV-2 infected mouse tissues, conducted histological or immunofluorescence analysis in SARS-CoV-2 infected mouse tissues. We also injected intranasally AAV-hACE2 or intraperitoneally NLRP3 inflammasome inhibitor MCC950 before SARS-CoV-2 infection in mice as indicated.

Findings

We have provided multiple lines of evidence that the NLRP3 inflammasome plays an important role in the host immune response to SARS-CoV-2 invasion of the lungs. Inhibition of the NLRP3 inflammasome attenuated the release of COVID-19 related pro-inflammatory cytokines in cell cultures and mice. The severe pathology induced by SARS-CoV-2 in lung tissues was reduced in Nlrp3^−/− mice compared to wild-type C57BL/6 mice. Finally, specific inhibition of the NLRP3 inflammasome by MCC950 alleviated excessive lung inflammation and thus COVID-19 like pathology in human ACE2 transgenic mice.

Interpretation

Inflammatory activation induced by SARS-CoV-2 is an important stimulator of COVID-19 related immunopathology. Targeting the NLRP3 inflammasome is a promising immune intervention against severe COVID-19 disease.

Funding

This work was supported by grants from the Bureau of Frontier Sciences and Education, CAS (grant no. QYZDJ-SSW-SMC005 to Y.G.Y.), the key project of the CAS “Light of West China” Program (to D.Y.) and Yunnan Province (202001AS070023 to D.Y.).

NLRP3 inflammasome activation and its inhibitory drugs in connection with COVID-19 infection

SARS-CoV-2 virus belongs to the beta coronavirus family that cause the inflammatory condition, acute pneumonia, and acute respiratory distress syndrome (ARDS). ARDS is the most important reason of mortality in patients, characterized as a highly increased levels of pro-inflammatory cytokine secretion. Inflammasome is a complex, which has an essential role in inflammatory situation, and NOD, LRR- and pyrin domain-containing protein 3 (NLRP3) is the most studied inflammasome that is considered to play vital roles in the virus infection and its pathogenesis. Our search language was limited to English and the search was performed in Web of Science, PubMed and Embase. Based on published articles, our current narrative review first explains the structure of the SARS-Cov2 virus and then describes the function of the NLRP3 inflammasome in relation to COVID-19 and drugs effective in controlling it. The NLRP3 inflammasome activation related to the initiation of inflammatory cascade including important cytokines production and releases such as IL-6, TNF-α and IL-1β. Thus, targeting the NLRP3 as a member of the innate immune system may be helpful for the reduction of ARDS clinical symptoms in COVID-19 patients.

COVID-19 infection and body weight: A deleterious liaison in a J-curve relationship

During the course of the COVID-19 pandemic, obesity has been shown to be an independent risk factor for high morbidity and mortality. Obesity confers poor outcomes in younger (<60 years) patients, an age-group considered low-risk for complications, a privilege that is negated by obesity. Findings are consistent, the higher the body mass index (BMI) the worse the outcomes. Ectopic (visceral) obesity also promotes proinflammatory, prothrombotic, and vasoconstrictive states, thus enhancing the deleterious effects of COVID-19 disease. Less, albeit robust, evidence also exists for a higher risk of COVID-19 infection incurred with underweight. Thus, the relationship of COVID-19 and BMI has a J-curve pattern, where patients with both overweight/obesity and underweight are more susceptible to the ailments of COVID-19. The pathophysiology underlying this link is multifactorial, mostly relating to the inflammatory state characterizing obesity, the impaired immune response to infectious agents coupled with increased viral load, the overexpression in adipose tissue of the receptors and proteases for viral entry, an increased sympathetic activity, limited cardiorespiratory reserve, a prothrombotic milieu, and the associated comorbidities. All these issues are herein reviewed, the results of large studies and meta-analyses are tabulated and the pathogenetic mechanisms and the BMI relationship with COVID-19 are pictorially illustrated.

Drug delivery systems as immunomodulators for therapy of infectious disease: Relevance to COVID-19

The emergence of SARS-CoV-2, and the ensuing global pandemic, has resulted in an unprecedented response to identify therapies that can limit uncontrolled inflammation observed in patients with moderate to severe COVID-19. The immune pathology behind COVID-19 is complex and involves the activation and interaction of multiple systems including, but not limited to, complement, inflammasomes, endothelial as well as innate and adaptive immune cells to bring about a convoluted profile of inflammation, coagulation and tissue damage. To date, therapeutic approaches have focussed on inhibition of coagulation, untargeted immune suppression and/or cytokine-directed blocking agents. Regardless of recently achieved improvements in individual patient outcomes and survival rates, improved and focussed approaches targeting individual systems involved is needed to further improve prognosis and wellbeing. This review summarizes the current understanding of molecular and cellular systems involved in the pathophysiology of COVID-19, and their contribution to pathogen clearance and damage to then discuss possible therapeutic options involving immunomodulatory drug delivery systems as well as summarising the complex interplay between them.

Adverse Cardiovascular Effects of Anti-COVID-19 Drugs

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) or COVID-19 infection is the cause of the ongoing global pandemic. Mortality from COVID-19 infection is particularly high in patients with cardiovascular diseases. In addition, COVID-19 patients with preexisting cardiovascular comorbidities have a higher risk of death. Main cardiovascular complications of COVID-19 are myocardial infarction, myocarditis, acute myocardial injury, arrhythmias, heart failure, stroke, and venous thromboembolism. Therapeutic interventions in terms of drugs for COVID-19 have many cardiac adverse effects. Here, we review the relative therapeutic efficacy and adverse effects of anti-COVID-19 drugs.

Possible mechanisms of cholesterol elevation aggravating COVID-19

Importance: Despite the availability of a vaccine against the severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2), humans will have to live with this virus and the after-effects of the coronavirus disease 2019 (COVID-19) infection for a long time. Cholesterol plays an important role in the infection and prognosis of SARS-CoV-2, and the study of its mechanism is of great significance not only for the treatment of COVID-19 but also for research on generic antiviral drugs. Observations: Cholesterol promotes the development of atherosclerosis by activating NLR family pyrin domain containing 3 (NLRP3), and the resulting inflammatory environment indirectly contributes to COVID-19 infection and subsequent deterioration. In in vitro studies, membrane cholesterol increased the number of viral entry sites on the host cell membrane and the number of angiotensin-converting enzyme 2 (ACE2) receptors in the membrane fusion site. Previous studies have shown that the fusion protein of the virus interacts with cholesterol, and the spike protein of SARS-CoV-2 also requires cholesterol to enter the host cells. Cholesterol in blood interacts with the spike protein to promote the entry of spike cells, wherein the scavenger receptor class B type 1 (SR-B1) plays an important role. Because of the cardiovascular protective effects of lipid-lowering therapy and the additional anti-inflammatory effects of lipid-lowering drugs, it is currently recommended to continue lipid-lowering therapy for patients with COVID-19, but the safety of extremely low LDL-C is questionable. Conclusions and Relevance: Cholesterol can indirectly increase the susceptibility of patients to SARS-CoV-2 and increase the risk of death from COVID-19, which are mediated by NLRP3 and atherosclerotic plaques, respectively. Cholesterol present in the host cell membrane, virus, and blood may also directly participate in the virus cell entry process, but the specific mechanism still needs further study. Patients with COVID-19 are recommended to continue lipid-lowering therapy.

Tranilast: a potential anti-Inflammatory and NLRP3 inflammasome inhibitor drug for COVID-19

SARS-CoV-2 is a type of beta-CoV that develops acute pneumonia, which is an inflammatory condition. A cytokine storm has been recognized as one of the leading causes of death in patients with COVID-19. ALI and ARDS along with multiple organ failure have also been presented as the consequences of acute inflammation and cytokine storm. It has been previously confirmed that SARS-CoV, as another member of the beta-CoV family, activates NLRP3 inflammasome and consequently develops acute inflammation in a variety of ways through having complex interactions with the host immune system using structural and nonstructural proteins. Numerous studies conducted on Tranilast have further demonstrated that the given drug can act as an effective anti-chemotactic factor on controlling inflammation, and thus, it can possibly help the improvement of the acute form of COVID-19 by inhibiting some key inflammation-associated transcription factors such as NF-κB and impeding NLRP3 inflammasome. Several studies have comparably revealed the direct effect of this drug on the prevention of inappropriate tissue's remodeling; inhibition of neutrophils, IL-5, and eosinophils; repression of inflammatory cell infiltration into inflammation site; restriction of factors involved in acute airway inflammation like IL-33; and suppression of cytokine IL-13, which increase mucosal secretions. Therefore, Tranilast may be considered as a potential treatment for patients with the acute form of COVID-19 along with other drugs.

Remdesivir Alleviates Acute Kidney Injury by Inhibiting the Activation of NLRP3 Inflammasome

Acute kidney injury (AKI) is a frequent clinical complication in critically ill patients, and it rapidly develops into renal failure with high morbidity and mortality. However, other than dialysis, no effective therapeutic interventions can offer reliable treatment to limit renal injury and improve survival. Here, we firstly reported that remdesivir (RDV, GS-5734), a broad-spectrum antiviral nucleotide prodrug, alleviated AKI by specifically inhibiting NOD-, LRR-, and pyrin domain-containing protein 3 (NLRP3) inflammasome activation in macrophages. Mechanically, RDV effectively suppressed the activities of nuclear transcription factor (NF)-κB, mitogen-activated protein kinase (MAPK), which further led to the reduction of the inflammasome genes of NLRP3 transcription, limiting the activation of NLRP3 inflammasome in vivo and in vitro. RDV also inhibited other pro-inflammatory genes including tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), IL-12, IL-1β, and interferon–β (IFN-β), leading to the reduction of inflammatory factors release. Thus, RDV can ameliorate AKI via modulating macrophage inflammasome activation and inflammatory immune responses and may have a therapeutic potential for patients with AKI in clinical application.

Drug repurposing of dermatologic medications to treat coronavirus disease 2019: Science or fiction?

No pharmaceutical products have been demonstrated to be safe and effective to specifically treat coronavirus disease 2019 (COVID-19); therefore, the therapy administered to infected patients remains symptomatic and empiric. Alongside the development of new, often high-cost drugs, a different tactic is being applied in parallel, investigating long-established, inexpensive medications originally designed for a variety of diseases to study their potential in treating COVID-19. The skin is the largest organ of the human body. With more than 3,000 skin conditions identified, the specialty of dermatology offers a rich armamentarium of systemic therapeutic agents aimed to treat the various chronic immunologically mediated, metabolic, infectious, occupational, inherited, or paraneoplastic dermatoses. Dermatologists have extensive experience with many drugs that have demonstrated promising in vitro antiviral action (directly targeting the viral replication). Many of these drugs have been used as nonspecific immunosuppressive strategies, such as glucocorticoids, synthetic antimalarials, colchicine, or other immunomodulators, and a number of targeted therapeutics have been directed at controlling hyperinflammatory processes similar to the "cytokine storm" associated with COVID-19 infection. We discuss several dermatologic drugs that have already been used or may have a promising role in the treatment of COVID-19.

Vaccines and drugs under clinical trials for prevention and treatment of COVID-19

The uncertainty related to prevention and treatment of Coronavirus disease 2019 due to lack of effective vaccine candidates or drug molecules has resulted in extensive spread of infection and mortality worldwide. Although the asymptomatic or mild patients are becoming healthy with regular over-the-counter medicines and proper rest and care, for the severe patients, in the absence of definite cure, different drug combinations are being used to treat on trial basis without the assurance of efficacy and safety. This scenario has however changed now with some medicines including antiviral Remdesivir and Favipiravir and anti-inflammatory drugs like dexamethasone and tocilizumab which have shown some positive results in trials such as decreasing need of mechanical or non-invasive ventilation or mortality. Further, a number of vaccine candidates are currently in pipeline and in advance stages of clinical trials, which will enhance their prospects in determining how the disease will be controlled in the times to come. In this article, an account of the under-trial potential drugs and vaccine candidates has been provided, and their future prospects have been discussed.

COVID-19 Pathophysiology Predicts That Ischemic Stroke Occurrence Is an Expectation, Not an Exception-A Systematic Review

Clinical reports of neurological manifestations associated with severe coronavirus disease 2019 (COVID-19), such as acute ischemic stroke (AIS), encephalopathy, seizures, headaches, acute necrotizing encephalitis, cerebral microbleeds, posterior reversible leukoencephalopathy syndrome, hemophagocytic lymphohistiocytosis, peripheral neuropathy, cranial nerve palsies, transverse myelitis, and demyelinating disorders, are increasing rapidly. However, there are comparatively few studies investigating the potential impact of immunological responses secondary to hypoxia, oxidative stress, and excessive platelet-induced aggregation on the brain. This scoping review has focused on the pathophysiological mechanisms associated with peripheral and consequential neural (central) inflammation leading to COVID-19-related ischemic strokes. It also highlights the common biological processes shared between AIS and COVID-19 infection and the importance of the recognition that severe respiratory dysfunction and neurological impairments associated with COVID and chronic inflammation [post-COVID-19 neurological syndrome (PCNS)] may significantly impact recovery and ability to benefit from neurorehabilitation. This study provides a comprehensive review of the pathobiology of COVID-19 and ischemic stroke. It also affirms that the immunological contribution to the pathophysiology of COVID-19 is predictive of the neurological sequelae particularly ischemic stroke, which makes it the expectation rather than the exception. This work is of fundamental significance to the neurorehabilitation community given the increasing number of COVID-related ischemic strokes, the current limited knowledge regarding the risk of reinfection, and recent reports of a PCNS. It further highlights the need for global collaboration and research into new pathobiology-based neurorehabilitation treatment strategies and more integrated evidence-based care.

The hidden role of NLRP3 inflammasome in obesity-related COVID-19 exacerbations: Lessons for drug repurposing

COVID-19, the illness caused by SARS-CoV-2, has a wide-ranging clinical spectrum that, in the worst-case scenario, involves a rapid progression to severe acute respiratory syndrome and death. Epidemiological data show that obesity and diabetes are among the main risk factors associated with high morbidity and mortality. The increased susceptibility to SARS-CoV-2 infection documented in obesity-related metabolic derangements argues for initial defects in defence mechanisms, most likely due to an elevated systemic metabolic inflammation ("metaflammation"). The NLRP3 inflammasome is a master regulator of metaflammation and has a pivotal role in the pathophysiology of either obesity or diabetes. Here, we discuss the most recent findings suggesting contribution of NLRP3 inflammasome to the increase in complications in COVID-19 patients with diabesity. We also review current pharmacological strategies for COVID-19, focusing on treatments whose efficacy could be due, at least in part, to interference with the activation of the NLRP3 inflammasome. LINKED ARTICLES: This article is part of a themed issue on The Pharmacology of COVID-19. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v177.21/issuetoc.