NLRP3 inflammasome and interleukin-1 contributions to COVID-19-associated coagulopathy and immunothrombosis.

Immunothrombosis - immune-mediated activation of coagulation - is protective against pathogens, but excessive immunothrombosis can result in pathological thrombosis and multiorgan damage, as in severe Coronavirus Disease 2019 (COVID-19). The NACHT-, LRR- and pyrin domain-containing protein 3 (NLRP3) inflammasome produces major proinflammatory cytokines of the interleukin (IL)-1 family, IL-1ß and IL-18, and induces pyroptotic cell death. Activation of the NLRP3 inflammasome pathway also promotes immunothrombotic programs including release of neutrophil extracellular traps and tissue factor by leukocytes, and prothrombotic responses by platelets and the vascular endothelium. NLRP3 inflammasome activation occurs in patients with COVID-19 pneumonia. In preclinical models, NLRP3 inflammasome pathway blockade restrains COVID-19-like hyperinflammation and pathology. Anakinra, recombinant human IL-1 receptor antagonist, showed safety and efficacy, and is approved for the treatment of hypoxemic COVID-19 patients with early signs of hyperinflammation. The non-selective NLRP3 inhibitor colchicine reduced hospitalization and death in a subgroup of COVID-19 outpatients, but is not approved for the treatment of COVID-19. Additional COVID-19 trials testing NLRP3 inflammasome pathway blockers are inconclusive or ongoing. We herein outline the contribution of immunothrombosis to COVID-19-associated coagulopathy, and review preclinical and clinical evidence suggesting an engagement of the NLRP3 inflammasome pathway in the immunothrombotic pathogenesis of COVID-19. We also summarize current efforts to target the NLRP3 inflammasome pathway in COVID-19, and discuss challenges, unmet gaps and the therapeutic potential that inflammasome-targeted strategies may provide for inflammation-driven thrombotic disorders including COVID-19.

Inflammasome pathways

Inflammasomes are cytosolic multiprotein complexes. They are an important component of the innate immune system, and their activation is a process for inflammation. Their pathologies cause for many autoinflammatory diseases such as familial Mediterranean fever (FMF), cryopyrin associated periodic fever syndrome (CAPS), and autoimmune disorders. The NLRP3 inflammasome is the most famous one. Inflammasome activation pathways are canonical, non-canonical, and alternative. There is a two-step model in which signal 1 is for priming and signal 2 is for activation. Inflammasome formation is triggered by sensors of danger or damage associated molecular patterns (DAMPs) or pathogen-associated molecular patterns (PAMPs). In response to these stimuli, the caspase-1 enzyme is activated. And it converts the proactive form of interleukin (IL)-1 beta to active IL-1beta and the same procedure for IL-18 which are pro-inflammatory cytokines. According to recent studies, COVID-19 infection also has the potential to activate inflammasomes to induce hyperinflammation which may be related to disease severity. © 2023 Nova Science Publishers, Inc. All rights reserved.

Senotherapeutics: An emerging approach to the treatment of viral infectious diseases in the elderly.

In the context of the global COVID-19 pandemic, the phenomenon that the elderly have higher morbidity and mortality is of great concern. Existing evidence suggests that senescence and viral infection interact with each other. Viral infection can lead to the aggravation of senescence through multiple pathways, while virus-induced senescence combined with existing senescence in the elderly aggravates the severity of viral infections and promotes excessive age-related inflammation and multiple organ damage or dysfunction, ultimately resulting in higher mortality. The underlying mechanisms may involve mitochondrial dysfunction, abnormal activation of the cGAS-STING pathway and NLRP3 inflammasome, the role of pre-activated macrophages and over-recruited immune cells, and accumulation of immune cells with trained immunity. Thus, senescence-targeted drugs were shown to have positive effects on the treatment of viral infectious diseases in the elderly, which has received great attention and extensive research. Therefore, this review focused on the relationship between senescence and viral infection, as well as the significance of senotherapeutics for the treatment of viral infectious diseases.

NLRP3 Inflammasome: A key contributor to the inflammation formation.

Inflammation is an important part of the development of various organ diseases. The inflammasome, as an innate immune receptor, plays an important role in the formation of inflammation. Among various inflammasomes, the NLRP3 inflammasome is the most well studied. The NLRP3 inflammasome is composed of skeletal protein NLRP3, apoptosis-associated speck-like protein (ASC) and pro-caspase-1. There are three types of activation pathways: (1) "classical" activation pathway; (2) "non-canonical" activation pathway; (3) "alternative" activation pathway. The activation of NLRP3 inflammasome is involved in many inflammatory diseases. A variety of factors (such as genetic factors, environmental factors, chemical factors, viral infection, etc.) have been proved to activate NLRP3 inflammasome and promote the inflammatory response of the lung, heart, liver, kidney and other organs in the body. Especially, the mechanism of NLRP3 inflammation and its related molecules in its associated diseases remains not to be summarized, namely they may promote or delay inflammatory diseases in different cells and tissues. This article reviews the structure and function of the NLRP3 inflammasome and its role in various inflammations, including inflammations caused by chemically toxic substances.

Heat-killed Lactobacillus murinus confers neuroprotection against dopamine neuronal loss by targeting NLRP3 inflammasome.

The intestinal flora has become very active in studies related to Parkinson's disease (PD) in recent years. The microbe-gut-brain axis is closely related to the maintenance of brain homeostasis as well as PD pathogenesis. Alterations in gut bacteria can contribute to neuroinflammation and dopamine (DA) neurodegeneration. Lactobacillus murinus, a gram-positive bacterium, is a commensal gut bacteria present in the mammalian gut and considered as a potential probiotic due to its beneficial effects, including anti-inflammatory and antibacterial actions. In this study, the effects of live L. murinus and heat-killed L. murinus on DA neuronal damage in rats and the underlying mechanisms were investigated. Data showed that heat-killed L. murinus ameliorated 6-hydroxydopamine-induced motor dysfunctions and loss of substantia nigra DA neurons, while no protection was shown in live L. murinus treatment. At the same time, heat-killed L. murinus reduced the activation of NLRP3 inflammasome in microglia and the secretion of pro-inflammatory factors, thus inhibiting the development of neuroinflammation. Furthermore, heat-killed L. murinus failed to display its original neuroprotective properties in NLRP3 inflammasome knockout mice. Together, heat-killed L. murinus conferred neuroprotection against DA neuronal loss via the inhibition of microglial NLRP3 inflammasome activation. These findings provide a promising potential for future applications of L. murinus, and also beneficial strategy for PD treatment.

SARS-COV-2 viroporins activate the NLRP3-inflammasome by the mitochondrial permeability transition pore.

Background: Compared to healthy controls, severe COVID19 patients display increased levels of activated NLRP3-inflammasome (NLRP3-I) and interleukin (IL)-1ß. SARS-CoV-2 encodes viroporin proteins E and Orf3a(2-E+2-3a) with homologs to SARS-CoV-1, 1-E+1-3a, which elevate NLRP3-I activation; by an unknown mechanism. Thus, we investigated how 2-E+2-3a activates the NLRP3-I to better understand the pathophysiology of severe COVID-19. Methods: We generated a polycistronic expression-vector co-expressing 2-E+2-3a from a single transcript. To elucidate how 2-E+2-3a activates the NLRP3-I, we reconstituted the NLRP3-I in 293T cells and used THP1-derived macrophages to monitor the secretion of mature IL-1ß. Mitochondrial physiology was assessed using fluorescent microscopy and plate reader assays, and the release of mitochondrial DNA (mtDNA) was detected from cytosolic-enriched fractions using Real-Time PCR. Results: Expression of 2-E+2-3a in 293T cells increased cytosolic Ca++ and elevated mitochondrial Ca++, taken up through the MCUi11-sensitive mitochondrial calcium uniporter. Increased mitochondrial Ca++ stimulated NADH, mitochondrial reactive oxygen species (mROS) production and the release of mtDNA into the cytosol. Expression of 2-E+2-3a in NLRP3-I reconstituted 293T cells and THP1-derived macrophages displayed increased secretion of IL-1ß. Increasing mitochondrial antioxidant defenses via treatment with MnTBAP or genetic expression of mCAT abolished 2-E+2-3a elevation of mROS, cytosolic mtDNA levels, and secretion of NLRP3-activated-IL-1ß. The 2-E+2-3a-induced release of mtDNA and the secretion of NLRP3-activated-IL-1ß were absent in cells lacking mtDNA and blocked in cells treated with the mitochondrial-permeability-pore(mtPTP)-specific inhibitor NIM811. Conclusion: Our findings revealed that mROS activates the release of mitochondrial DNA via the NIM811-sensitive mitochondrial-permeability-pore(mtPTP), activating the inflammasome. Hence, interventions targeting mROS and the mtPTP may mitigate the severity of COVID-19 cytokine storms.

The Potential Effect of Dapsone on the Inflammatory Reactions in Covid-19: Staggering view.

Severe SARS-CoV-2 infection is linked with an overstated immune response with the succeeding release of pro-inflammatory cytokines and progression of the cytokine storm. In addition, severe SARS-CoV-2 infection is associated with the development of oxidative stress and coagulopathy. Dapsone (DPS) is a bacteriostatic antibiotic that has a potent anti-inflammatory effect. Thus, this mini-review aimed to elucidate the potential role of DPS in mitigating inflammatory disorders in Covid-19 patients. DPS inhibits neutrophil myeloperoxidase, inflammation, and neutrophil chemotaxis. Therefore, DPS could be effective against neutrophilia-induced complications in Covid-19. In addition, DPS could be effective in mitigating inflammatory and oxidative stress disorders by suppressing the expression of inflammatory signaling pathways and the generation of reactive oxygen species (ROS) correspondingly. In conclusion, DPS might be effective in the management of Covid-19 through the attenuation of inflammatory disorders. Therefore, preclinical and clinical studies are reasonable in this regard.

New insights into the regulatory roles of glutathione in NLRP3-inflammasome-mediated immune and inflammatory responses.

Glutathione (GSH) is the most abundant non-protein thiol (-SH) in mammalian cells. Its synthesis and metabolism serve to maintain cellular reduction-oxidation (redox) homeostasis, which is important for multiple cellular processes including proliferation, differentiation and death. An accumulating body of evidence suggests that the essential roles of GSH extended far beyond its oxidant and electrophile scavenger activities and regulatory role in the lifespan of cells. Recent findings revealed that altered GSH levels are closely associated with a wide range of pathologies including bacterial and viral infections, neurodegenerative diseases and autoimmune disorders, all of which are also characterized by aberrant activation of the NLR family pyrin domain containing 3 (NLRP3) inflammasome. As a result of these findings, GSH was assigned a central role in influencing the activation of the NLRP3 inflammasome. To expand on our recent advances in understanding this process, we discuss here the emerging roles of GSH in activation of the NLRP3 inflammasome, and the therapeutic potential of GSH in its associated pathologies.

Panax ginseng as a potential therapeutic for neurological disorders associated with COVID-19; Toward targeting inflammasome.

Coronavirus disease 2019 (COVID-19) is a highly infectious respiratory disease caused by a severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2). SARS-CoV-2 infection may cause clinical manifestations of multiple organ damage, including various neurological syndromes. There are currently two oral antiviral drugs-Paxlovid and molnupiravir-that are recognized to treat COVID-19, but there are still no drugs that can specifically fight the challenges of SARS-CoV-2 variants. Nucleotide-binding oligomerization domain-like receptor pyrin domain-containing-3 (NLRP3) inflammasome is a multimolecular complex that can sense heterogeneous pathogen-associated molecular patterns associated with neurological disorders. The NLRP3 activation stimulates the production of caspase-1-mediated interleukin (IL)-1ß, IL-18, and other cytokines in immune cells. Panax (P.) ginseng is a medicinal plant that has traditionally been widely used to boost immunity and treat various pathological conditions in the nervous system due to its safety and anti-inflammatory/oxidant/viral activities. Several recent reports have indicated that P. ginseng and its active ingredients may regulate NLRP3 inflammasome activation in the nervous system. Therefore, this review article discusses the current knowledge regarding the pathogenesis of neurological disorders related to COVID-19 and NLRP3 inflammasome activation and the possibility of using P. ginseng in a strategy targeting this pathway to treat neurological disorders.

A protective erythropoietin evolutionary landscape, NLRP3 inflammasome regulation, and multisystem inflammatory syndrome in children.

The low incidence of pediatric severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection and the associated multisystem inflammatory syndrome (MIS-C) lack a unifying pathophysiological explanation, impeding effective prevention and therapy. Activation of the NACHT, LRR, and PYD domains-containing protein (NLRP) 3 inflammasome in SARS-CoV-2 with perturbed regulation in MIS-C, has been reported. We posit that, early age physiological states and genetic determinants, such as certain polymorphisms of renin-angiotensin aldosterone system (RAAS) molecules, promote a controlled RAAS hyperactive state, and form an evolutionary landscape involving an age-dependent erythropoietin (EPO) elevation, mediating ancestral innate immune defenses that, through appropriate NLRP3 regulation, mitigate tissue injury and pathogen invasion. SARS-CoV-2-induced downregulation of angiotensin-converting enzyme (ACE)2 expression in endothelial cells (EC), impairment of endothelial nitric oxide (NO) synthase (eNOS) activity and downstream NO bioavailability, may promote a hyperactive RAAS with elevated angiotensin II and aldosterone that, can trigger, and accelerate NLRP3 inflammasome activation, while EPO-eNOS/NO abrogate it. Young age and a protective EPO evolutionary landscape may successfully inhibit SARS-CoV-2 and contain NLRP3 inflammasome activation. By contrast, increasing age and falling EPO levels, in genetically susceptible children with adverse genetic variants and co-morbidities, may lead to unopposed RAAS hyperactivity, NLRP3 inflammasome dysregulation, severe endotheliitis with pyroptotic cytokine storm, and development of autoantibodies, as already described in MIS-C. Our haplotype estimates, predicted from allele frequencies in population databases, are in concordance with MIS-C incidence reports in Europeans but indicate lower risks for Asians and African Americans. Targeted Mendelian approaches dissecting the influence of relevant genetic variants are needed.

Luteolin-rich fraction from Perilla frutescens seed meal inhibits spike glycoprotein S1 of SARS-CoV-2-induced NLRP3 inflammasome lung cell inflammation via regulation of JAK1/STAT3 pathway: A potential anti-inflammatory compound against inflammation-induced long-COVID.

Objective: The multi-systemic inflammation as a result of COVID-19 can persevere long after the initial symptoms of the illness have subsided. These effects are referred to as Long-COVID. Our research focused on the contribution of the Spike protein S1 subunit of SARS-CoV-2 (Spike S1) on the lung inflammation mediated by NLRP3 inflammasome machinery and the cytokine releases, interleukin 6 (IL-6), IL-1beta, and IL-18, in lung epithelial cells. This study has attempted to identify the naturally- occurring agents that act against inflammation-related long-COVID. The seed meal of Perilla frutescens (P. frutescens), which contains two major dietary polyphenols (rosmarinic acid and luteolin), has been reported to exhibit anti-inflammation activities. Therefore, we have established the ethyl acetate fraction of P. frutescens seed meal (PFEA) and determined its anti-inflammatory effects on Spike S1 exposure in A549 lung cells. Methods: PFEA was established using solvent-partitioned extraction. Rosmarinic acid (Ra) and luteolin (Lu) in PFEA were identified using the HPLC technique. The inhibitory effects of PFEA and its active compounds against Spike S1-induced inflammatory response in A549 cells were determined by RT-PCR and ELISA. The mechanistic study of anti-inflammatory properties of PFEA and Lu were determined using western blot technique. Results: PFEA was found to contain Ra (388.70 ± 11.12 mg/g extract) and Lu (248.82 ± 12.34 mg/g extract) as its major polyphenols. Accordingly, A549 lung cells were pre-treated with PFEA (12.5-100 µg/mL) and its two major compounds (2.5-20 µg/mL) prior to the Spike S1 exposure at 100 ng/mL. PFEA dose-dependently exhibited anti-inflammatory properties upon Spike S1-exposed A549 cells through IL-6, IL-1ß, IL-18, and NLRP3 gene suppressions, as well as IL-6, IL-1ß, and IL-18 cytokine releases with statistical significance (p < 0.05). Importantly, Lu possesses superior anti-inflammatory properties when compared with Ra (p < 0.01). Mechanistically, PFEA and Lu effectively attenuated a Spike S1-induced inflammatory response through downregulation of the JAK1/STAT3-inflammasome-dependent inflammatory pathway as evidenced by the downregulation of NLRP3, ASC, and cleaved-caspase-1 of the NLRP3 inflammasome components and by modulating the phosphorylation of JAK1 and STAT3 proteins (p < 0.05). Conclusion: The findings suggested that luteolin and PFEA can modulate the signaling cascades that regulate Spike S1-induced lung inflammation during the incidence of Long-COVID. Consequently, luteolin and P. frutescens may be introduced as potential candidates in the preventive therapeutic strategy for inflammation-related post-acute sequelae of COVID-19.

Eugenol Alleviates TGEV-Induced Intestinal Injury via Suppressing ROS/NLRP3/GSDMD-Dependent Pyroptosis.

Transmissible gastroenteritis virus (TGEV), a coronavirus, is one of the main causative agents of diarrhea in piglets and significantly impacts the global swine industry. Pyroptosis is involved in the pathogenesis of coronavirus, but its role in TGEV-induced intestinal injury has yet to be fully elucidated. Eugenol, an essential plant oil, plays a vital role in antiviral innate immune responses. We demonstrate the preventive effect of eugenol on TGEV infection. Eugenol alleviates TGEV-induced intestinal epithelial cell pyroptosis and reduces intestinal injury in TGEV-infected piglets. Mechanistically, eugenol reduces the activation of NLRP3 inflammasome, thereby inhibiting TGEV-induced intestinal epithelial cell pyroptosis. In addition, eugenol scavenges TGEV-induced reactive oxygen species (ROS) increase, which in turn prevents TGEV-induced NLRP3 inflammasome activation and pyroptosis. Overall, eugenol protects the intestine by reducing TGEV-induced pyroptosis through inhibition of NLRP3 inflammasome activation, which may be mediated through intracellular ROS levels. These findings propose that eugenol may be an effective strategy to prevent TGEV infection.

A bibliometric analysis of NLRP3 inflammasome in acute lung injury/acute respiratory distress syndrome from 2010 to 2021.

Background: Nod-like receptor family pyrin domain containing 3 (NLRP3) inflammasome is essential in the pathogenesis of acute respiratory distress syndrome (ARDS), a fatal clinical syndrome that deteriorated from acute lung injury (ALI). This bibliometric study aims to offer a thorough insight into the scientific output about NLRP3 inflammasome in ALI/ARDS and explore the intellectual base, developing trajectory and emerging trends. Methods: We retrieved the literature from 2010 to 2021 from Science Citation Index Expanded (SCIE) database. Bibliometrix (3.1.4) R package and CiteSpace (5.8.R3) were used for further analysis and visualization. Results: A total of 508 English articles and reviews published from 2010 to 2021 were identified. The annual number of publications presented a rapidly developing trend especially in recent years. Among all the 42 countries, China was the most productive and most cited country, while the USA had the greatest impact. Peter A. Ward from the USA was the most productive corresponding author, and 4 of these top 10 corresponding authors were from China. The most cited reference was written by Ahmed (2017) of Zhejiang University in China. The Journal of Immunology had highest citation count and G-index. Furthermore, the major disciplines of research front have drifted from "Medicine, Medical, Clinical" to "Molecular, Biology, Immunology" over the past 12 years. In the co-occurring network, the terms "acute lung injury," "NLRP3 inflammasome," "interleukin-1ß," "NF-κB," and "NLRP3 activation" occurred most frequently, while in burst detection, "oxidative stress" had the highest burst strength. Co-citation network revealed that Cluster 2 "virus infection" was the most active area, including the most citation bursts. Cluster 0 "severe COVID-19" and Cluster 1 "dual inhibitor PTUPB" were emerging themes in recent years, and they involved the largest number of publications. Conclusions: This bibliometric analysis revealed a rapid growth trend of the relatively novel topic: NLRP3 inflammasome in ALI/ARDS. China was the largest contributor, while the USA offered the most landmark papers. The major disciplines of research front drifted from "Medicine, Medical, Clinical" to "Molecular, Biology, Immunology." In recent years, studies about the role of NLRP3 in COVID-19-associated ALI/ARDS and oxidative stress became hot spots.

Complete, Rapid Resolution of Severe Bilateral Pneumonia and Acute Respiratory Distress Syndrome in a COVID-19 Patient: Role for a Unique Therapeutic Combination of Inhalations With Bromhexine, Higher Doses of Colchicine, and Hymecromone.

An otherwise healthy, 35-year-old man was hospitalized for the management of acute respiratory failure due to coronavirus disease 2019 (COVID-19)-related severe bilateral pneumonia and acute respiratory distress syndrome (ARDS). The patient therapeutic regimen included the widely accepted standard combination of oxygen, anticoagulation therapy; corticosteroids, non-steroidal anti-inflammatory drugs (NSAIDs), and antibiotics. A novel combination of colchicine, hymecromone, and bromhexine inhalations was added to the therapeutic regimen as part of our unique COVID-19 management institutional protocol. COVID-19-related severe bilateral pneumonia and acute respiratory distress syndrome (ARDS). The patient therapeutic regimen included the widely accepted standard combination of oxygen, anticoagulation therapy, corticosteroids, NSAIDs, and antibiotics. A novel combination of colchicine, hymecromone, and bromhexine inhalations was added to the therapeutic regimen as part of our unique COVID-19 management institutional protocol. Rapid clinical response on day 2, with a significant improvement of radiographic pulmonary changes on day 5, and improvement of laboratory results on days 5-7 were observed. The administration of inhalatory bromhexine in combination with high-dose colchicine and hymecromone was crucial for the positive outcome of the disease. This treatment regimen resulted in a four to five-fold decrease in the mortality of hospitalized patients.

Xuanfei Baidu formula alleviates impaired mitochondrial dynamics and activated NLRP3 inflammasome by repressing NF-κB and MAPK pathways in LPS-induced ALI and inflammation models.

BACKGROUND: Xuanfei Baidu Formula (XBF) is an effective traditional Chinese medicine (TCM) remedy for treating coronavirus disease 2019 (COVID-19) in China. This herbal medicine has shown effects in reducing clinical symptoms and shortening the average length of hospital stay for COVID-19 patients. Previous studies have demonstrated that XBF alleviates acute lung injury (ALI) by regulating macrophage-mediated immune inflammation, but the mechanisms of action remain elusive. PURPOSE: This study aimed to evaluate the lung-protective and anti-inflammatory effects of XBF and its underlying mechanisms. METHODS: Here, XBF's effects were investigated in an ALI mouse model induced by inhalation of atomized lipopolysaccharide (LPS). Besides, the LPS-induced inflammation model in RAW264.7 cells was used to clarify the underlying mechanisms of XBF against ALI. RESULTS: Our results showed that XBF treatment alleviated LPS-induced lung injury, as evidenced by reduced histopathological changes, pulmonary alveoli permeability, fibrosis, and apoptosis in the lung tissues. In addition, inflammation was alleviated as shown by decreased levels of tumor necrosis factor (TNF)-α, interleukin (IL)-6, IL-1ß in serum and bronchoalveolar lavage fluid (BALF), and reduced white blood cell (WBC) count in BALF. Furthermore, consistent with the in vivo assay, XBF inhibited LPS-induced inflammatory cytokines release and pro-inflammatory polarization in RAW264.7 cells. Mechanistically, XBF increased mitochondrial fusion by upregulating Mfn1 and attenuated NLRP3 inflammasome activation by repressing Casp11, respectively, to inhibit NF-κB and MAPK pathways, thus repressing pro-inflammatory macrophage polarization. CONCLUSION: In this study, we demonstrate that XBF exerts anti-ALI and -inflammatory effects by recovering mitochondrial dynamics and reducing inflammasome activation, providing a biological illustration of the clinical efficacy of XBF in treating COVID-19 patients.

Interleukin-1 and the NLRP3 inflammasome in COVID-19: Pathogenetic and therapeutic implications.

A hyperinflammatory response during severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection crucially worsens clinical evolution of coronavirus disease 2019 (COVID-19). The interaction between SARS-CoV-2 and angiotensin-converting enzyme 2 (ACE2) triggers the activation of the NACHT, leucine-rich repeat, and pyrin domain-containing protein 3 (NLRP3) inflammasome. Enhanced inflammasome activity has been associated with increased disease severity and poor prognosis. Evidence suggests that inflammasome activation and interleukin-1ß (IL-1ß) release aggravate pulmonary injury and induce hypercoagulability, favoring progression to respiratory failure and widespread thrombosis eventually leading to multiorgan failure and death. Observational studies with the IL-1 blockers anakinra and canakinumab provided promising results. In the SAVE-MORE trial, early treatment with anakinra significantly shortened hospital stay and improved survival in patients with moderate-to-severe COVID-19. In this review, we summarize current evidence supporting the pathogenetic role of the NLRP3 inflammasome and IL-1ß in COVID-19, and discuss clinical trials testing IL-1 inhibition in COVID-19.

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.

Assessing the suitability of long non-coding RNAs as therapeutic targets and biomarkers in SARS-CoV-2 infection.

Long non-coding RNAs (lncRNAs) are RNA transcripts that are over 200 nucleotides and rarely encode proteins or peptides. They regulate gene expression and protein activities and are heavily involved in many cellular processes such as cytokine secretion in respond to viral infection. In severe COVID-19 cases, hyperactivation of the immune system may cause an abnormally sharp increase in pro-inflammatory cytokines, known as cytokine release syndrome (CRS), which leads to severe tissue damage or even organ failure, raising COVID-19 mortality rate. In this review, we assessed the correlation between lncRNAs expression and cytokine release syndrome by comparing lncRNA profiles between COVID-19 patients and health controls, as well as between severe and non-severe cases. We also discussed the role of lncRNAs in CRS contributors and showed that the lncRNA profiles display consistency with patients' clinic symptoms, thus suggesting the potential of lncRNAs as drug targets or biomarkers in COVID-19 treatment.

Hesperetin from Root Extract of Clerodendrum petasites S. Moore Inhibits SARS-CoV-2 Spike Protein S1 Subunit-Induced NLRP3 Inflammasome in A549 Lung Cells via Modulation of the Akt/MAPK/AP-1 Pathway.

Inhibition of inflammatory responses from the spike glycoprotein of SARS-CoV-2 (Spike) by targeting NLRP3 inflammasome has recently been developed as an alternative form of supportive therapy besides the traditional anti-viral approaches. Clerodendrum petasites S. Moore (C. petasites) is a Thai traditional medicinal plant possessing antipyretic and anti-inflammatory activities. In this study, C. petasites ethanolic root extract (CpEE) underwent solvent-partitioned extraction to obtain the ethyl acetate fraction of C. petasites (CpEA). Subsequently, C. petasites extracts were determined for the flavonoid contents and anti-inflammatory properties against spike induction in the A549 lung cells. According to the HPLC results, CpEA significantly contained higher amounts of hesperidin and hesperetin flavonoids than CpEE (p < 0.05). A549 cells were then pre-treated with either C. petasites extracts or its active flavonoids and were primed with 100 ng/mL of spike S1 subunit (Spike S1) and determined for the anti-inflammatory properties. The results indicate that CpEA (compared with CpEE) and hesperetin (compared with hesperidin) exhibited greater anti-inflammatory properties upon Spike S1 induction through a significant reduction in IL-6, IL-1ß, and IL-18 cytokine releases in A549 cells culture supernatant (p < 0.05). Additionally, CpEA and hesperetin significantly inhibited the Spike S1-induced inflammatory gene expressions (NLRP3, IL-1ß, and IL-18, p < 0.05). Mechanistically, CpEA and hesperetin attenuated inflammasome machinery protein expressions (NLRP3, ASC, and Caspase-1), as well as inactivated the Akt/MAPK/AP-1 pathway. Overall, our findings could provide scientific-based evidence to support the use of C. petasites and hesperetin in the development of supportive therapies for the prevention of COVID-19-related chronic inflammation.