Inflammasomes: a rising star on the horizon of COVID-19 pathophysiology.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a contagious respiratory virus that is the cause of the coronavirus disease 2019 (COVID-19) pandemic which has posed a serious threat to public health. COVID-19 is characterized by a wide spectrum of clinical manifestations, ranging from asymptomatic infection to mild cold-like symptoms, severe pneumonia or even death. Inflammasomes are supramolecular signaling platforms that assemble in response to danger or microbial signals. Upon activation, inflammasomes mediate innate immune defense by favoring the release of proinflammatory cytokines and triggering pyroptotic cell death. Nevertheless, abnormalities in inflammasome functioning can result in a variety of human diseases such as autoimmune disorders and cancer. A growing body of evidence has showed that SARS-CoV-2 infection can induce inflammasome assembly. Dysregulated inflammasome activation and consequent cytokine burst have been associated with COVID-19 severity, alluding to the implication of inflammasomes in COVID-19 pathophysiology. Accordingly, an improved understanding of inflammasome-mediated inflammatory cascades in COVID-19 is essential to uncover the immunological mechanisms of COVID-19 pathology and identify effective therapeutic approaches for this devastating disease. In this review, we summarize the most recent findings on the interplay between SARS-CoV-2 and inflammasomes and the contribution of activated inflammasomes to COVID-19 progression. We dissect the mechanisms involving the inflammasome machinery in COVID-19 immunopathogenesis. In addition, we provide an overview of inflammasome-targeted therapies or antagonists that have potential clinical utility in COVID-19 treatment.

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.

Recent advances in ZBP1-derived PANoptosis against viral infections.

Innate immunity is an important first line of defense against pathogens, including viruses. These pathogen- and damage-associated molecular patterns (PAMPs and DAMPs, respectively), resulting in the induction of inflammatory cell death, are detected by specific innate immune sensors. Recently, Z-DNA binding protein 1 (ZBP1), also called the DNA-dependent activator of IFN regulatory factor (DAI) or DLM1, is reported to regulate inflammatory cell death as a central mediator during viral infection. ZBP1 is an interferon (IFN)-inducible gene that contains two Z-form nucleic acid-binding domains (Zα1 and Zα2) in the N-terminus and two receptor-interacting protein homotypic interaction motifs (RHIM1 and RHIM2) in the middle, which interact with other proteins with the RHIM domain. By sensing the entry of viral RNA, ZBP1 induces PANoptosis, which protects host cells against viral infections, such as influenza A virus (IAV) and herpes simplex virus (HSV1). However, some viruses, particularly coronaviruses (CoVs), induce PANoptosis to hyperactivate the immune system, leading to cytokine storm, organ failure, tissue damage, and even death. In this review, we discuss the molecular mechanism of ZBP1-derived PANoptosis and pro-inflammatory cytokines that influence the double-edged sword of results in the host cell. Understanding the ZBP1-derived PANoptosis mechanism may be critical for improving therapeutic strategies.

Gasdermin D-mediated pyroptosis: mechanisms, diseases, and inhibitors.

Gasdermin D (GSDMD)-mediated pyroptosis and downstream inflammation are important self-protection mechanisms against stimuli and infections. Hosts can defend against intracellular bacterial infections by inducing cell pyroptosis, which triggers the clearance of pathogens. However, pyroptosis is a double-edged sword. Numerous studies have revealed the relationship between abnormal GSDMD activation and various inflammatory diseases, including sepsis, coronavirus disease 2019 (COVID-19), neurodegenerative diseases, nonalcoholic steatohepatitis (NASH), inflammatory bowel disease (IBD), and malignant tumors. GSDMD, a key pyroptosis-executing protein, is linked to inflammatory signal transduction, activation of various inflammasomes, and the release of downstream inflammatory cytokines. Thus, inhibiting GSDMD activation is considered an effective strategy for treating related inflammatory diseases. The study of the mechanism of GSDMD activation, the formation of GSDMD membrane pores, and the regulatory strategy of GSDMD-mediated pyroptosis is currently a hot topic. Moreover, studies of the structure of caspase-GSDMD complexes and more in-depth molecular mechanisms provide multiple strategies for the development of GSDMD inhibitors. This review will mainly discuss the structures of GSDMD and GSDMD pores, activation pathways, GSDMD-mediated diseases, and the development of GSDMD inhibitors.

A 360° view of the inflammasome: Mechanisms of activation, cell death, and diseases.

Inflammasomes are critical sentinels of the innate immune system that respond to threats to the host through recognition of distinct molecules, known as pathogen- or damage-associated molecular patterns (PAMPs/DAMPs), or disruptions of cellular homeostasis, referred to as homeostasis-altering molecular processes (HAMPs) or effector-triggered immunity (ETI). Several distinct proteins nucleate inflammasomes, including NLRP1, CARD8, NLRP3, NLRP6, NLRC4/NAIP, AIM2, pyrin, and caspases-4/-5/-11. This diverse array of sensors strengthens the inflammasome response through redundancy and plasticity. Here, we present an overview of these pathways, outlining the mechanisms of inflammasome formation, subcellular regulation, and pyroptosis, and discuss the wide-reaching effects of inflammasomes in human disease.

Activation of Inflammasome complex in nasopharyngeal epithelial cells from patients with Coronavirus disease 2019 contributes to inflammatory state and worse disease outcomes.

Pathogenesis of Coronavirus disease 2019 (COVID-19) has been associated with dysregulation of both adaptive and innate immune systems. Hence, we determined the contribution of inflammasome in the nasopharyngeal epithelial cells isolated from COVID-19 subjects to disease pathogenesis and outcomes. Epithelial cells from 150 COVID-19 patients and 150 healthy controls were yielded through nasopharyngeal swab sampling. Patients were categorized into three groups of those with clinical presentations/need hospitalization, with clinical presentations/no need hospitalization and cases without clinical symptoms/no need hospitalization. Finally, the transcriptional amount of inflammasome related genes were assessed in the nasopharyngeal epithelial cells using qPCR. There was a significant upregulation of nod-like receptor (NLR) family pyrin domain containing 1 (NLRP1), nod-like receptor (NLR) family pyrin domain containing 3 (NLRP3), Apoptosis-associated speck-like protein containing a CARD (ASC) and Caspase-1 mRNA expressions in patients compared to controls. NLRP1, NLRP3, ASC and Caspase-1 were upregulated in epithelial cells of patients with clinical symptoms/need hospitalization and cases with clinical symptoms/no need hospitalization when compared to controls. There was a correlation between expression of inflammasome-related genes and clinicopathological features. Abnormal expression of inflammasome-related genes in the nasopharyngeal epithelial cells obtained from COVID-19 patients may be of prognostic value to determine the intensity of the disease's outcomes and requirement for alternative supports in hospitals.

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.

SARS-CoV-2 VARIANTS-DEPENDENT INFLAMMASOME ACTIVATION

Background: Innate immunity is the first line of defense in response to pathogens, which acts locally and also leads the stimulation of adaptive immunity through at least with IL-1beta secretion. It has been shown that SARSCoV- 2 infection triggered the NLRP-3 inflammasome activation and the IL-1beta secretion. The aim of this study was to analyze and compare the level of IL-1beta secretion that is one of the most important innate immunity cytokines, in monocyte-like cells infected with 6 different variants of the SARS-CoV-2. Method(s): Six SARS-CoV-2 variants (historical (B.1, D614G), Alpha, Beta, Gamma, Delta and Omicron BA.1) were isolated from COVID-19 hospitalized patients. Viral stocks were obtained by inoculation in Vero and Vero-TRMPSS2 cells. THP-1 monocyte-like cells were cultured with RPMI-hepes 10% FBS-0.05 mM 2-mercaptoethanol. A total of 5 x 104 of THP-1 cells was plated per well in 96-wells plate and differentiated with 10nM of PMA for 24h. Differenciated- THP-1 were first primed with LPS 1mug/ml for 2h and infected with different SARS-CoV-2 variants with a MOI 0.1. IL-1beta was measured by luminescence in the supernatant after 24 h of infection. Result(s): We analyzed and compared IL-1beta secretion between SARS-CoV-2 virus 6 sublineages after infection of monocytes like THP-1. We observed that THP-1 cells infected with SARS-CoV-2 variants presented a significantly higher IL-1beta secretion than non-infected cells. Moreover, some SARS-CoV-2 variants led to a stronger IL-1beta secretion, and particularly we observed a significantly higher level of IL-1beta cells infected with Omicron BA.1 sublineage compared to other variants. Indeed, Omicron BA.1 infected cells presented the higher IL-1beta secretion (median 385.7 pg/ml IQR[302.6-426.3]) follows by the Delta variants and the historical variants (median 303.6 [266.3-391.9] and 281.9 [207.2-410], respectively). Alpha, Beta and Gamma variants presented the lowest IL-1beta secretion (median 228.1 [192.5-276.4], 219.1 [185.1-354.2] and 211 [149.8- 228.8]). Conclusion(s): We observed the inflammasome activation for the 6 SARS-CoV-2 sublineages with a variation in level of IL-1beta secretion. Indeed, our results suggested that Omicron BA.1 was more recognized by the innate immune cells than other SARS-CoV-2, which could in part, with its upper respiratory tract tropism, possibly explain its less clinical virulence. Taking together, these results suggest that the innate immunity response and precisely, IL-1beta secretion pathways were activated in a SARS-CoV-2 variants-dependent manner.

Thyroid Eye Disease Following COVID-19 Infection in a Patient with a History of Graves' Disease

Introduction: Autoimmune and inflammatory thyroid diseases have been reported following SARS-CoV-2 infection or vaccination, but thyroid eye disease (TED) post-COVID-19 infection is less common. We describe a case of TED following SAR-CoV-2 infection in a patient with a history of Graves' disease. Case Description: A 59-year-old female with history of Graves' disease status post radioiodine ablation therapy in 2002. She developed post-ablative hypothyroidism which has been stable on levothyroxine 88 mcg daily. In January 2021, the patient's husband and daughter were diagnosed with COVID-19 infection. A few days later, the patient developed an upper respiratory tract infection associated with loss of sense of smell and taste consistent with COVID-19 infection. Three days later, she developed bilateral watery eyes which progressed to eye redness, eyelid fullness, retraction, and pain with eye movement over 1-month duration. Her eye examination was significant for severe periocular soft tissue swelling, lagophthalmos and bilateral exophthalmos. The laboratory workup was consistent with normal TSH 0.388 mIU/L (0.358-3.740 mIU/L) and positive TSI 1.01 (0.0-0.55). The patient was referred to an Ophthalmologist for evaluation of TED. He noted bilateral exophthalmos, no restrictive ocular dysmotility or compressive optic neuropathy (clinical activity score 4/7 points). CT scan of orbit showed findings compatible with thyroid orbitopathy. Based on clinical activity score of 4, treatment with Teprotumumab was recommended pending insurance approval. Discussion(s): Many cases of new-onset Graves' hyperthyroidism have been reported after COVID-19, with only a few associated with TED. Our patient has been in remission for 20 years before she developed COVID-19 infection with occurence of TED.This suggests that COVID-19 infection may have played a role. SARS-CoV-2 may act through several mechanisms, including breakdown of central and peripheral tolerance, molecular mimicry between viral and self-antigens, stimulation of inflammasome with release of type I interferon. In our patient, treatment with Teprotumumab was indicated due to Graves' orbitopathy clinical activity score greater than or equal to 3. In conclusion, it is very uncommon for TED to present after COVID-19 infection. Our case reinforces the speculative hypothesis that SARS-CoV-2 virus could have triggered an autoimmune response against eye antigens. There is a need for increased awareness about the link between COVID-19 and autoimmunity to help better define the management of patients.Copyright © 2023

Inflammasome but Not Ifn-I/Iii Response Is Altered in Children with Long Covid

Background: Severe COVID-19 is less common in children than in adults. Increasing evidence show that distinct immune-pathological changes can persist weeks or months after SARS-CoV2 infection, leading to Long COVID (LC). We investigated the systemic type I/III interferon (IFN-I/III) and inflammation response in peripheral blood mononuclear cells (PBMCs) of children with and without LC symptoms. Method(s): Blood samples were collected from children attending Umberto I hospital of Rome, within 3-6 months after a SARS-CoV-2 positive test and from control children. RNA was extracted from PBMCs for determining the levels of IFN-I (IFN-Alpha2, -Beta, -Epsilon and -Omega), IFN-III (IFN-Lambda1-3), NLRP3 and IL-1beta genes, and miR-141 expression by quantitative RealTime-PCR assays, normalized to housekeeping GUS gene and RNU6B, respectively. Result(s): 28 participants (M 12.5y SD 3.0) with LC symptoms, 28 participants (M 11.8y SD 3.0) without LC symptoms and 18 children who've never had SARS-CoV- 2 infection (M 10.5y SD 3.1) were enrolled. Comparing the three study groups, we found reduced levels of IFN-Lambda1, IFN-Lambda2 and IFN-Lambda3 (p=0.006, p< 0.001, p=0.012, respectively;Kruskal-Wallis (KW) test) mRNA in patients who have had SARS-CoV-2 infection as opposed to control group, whereas transcript levels of IFN-Epsilon (p= 0.019;KW test) were increased in the former with respect to the latter group;as well, remaining IFN-I genes analyzed showed a tendency to be up-regulated. As far as NLRP3 and IL-1beta levels was concerned, these genes were increased in LC patients (p< 0.001 for both genes;KW test). Additionally, miR-141, which has been reported to regulate inflammasome response, was overexpressed in LC patients (p< 0.001;Mann-Whitney test). Conclusion(s): These results showed a decreased levels of IFN-III mRNAs and an overexpression of IFN-Epsilon in children after 3-6 months of SARS-CoV-2 infection regardless of development of LC symptoms, suggesting that SARSCoV- 2 could have caused dysregulation of IFN response through unknown mechanisms (e.g. epigenetic modifications). Also, we found an overexpression of miR-141, NLRP3 and IL-1beta mRNAs in LC patients, indicating that a prolonged activation of inflammasome pathways could be associated with the development of LC symptoms.

Bat ASC2 suppresses inflammasomes and ameliorates inflammatory diseases.

Bats are special in their ability to live long and host many emerging viruses. Our previous studies showed that bats have altered inflammasomes, which are central players in aging and infection. However, the role of inflammasome signaling in combating inflammatory diseases remains poorly understood. Here, we report bat ASC2 as a potent negative regulator of inflammasomes. Bat ASC2 is highly expressed at both the mRNA and protein levels and is highly potent in inhibiting human and mouse inflammasomes. Transgenic expression of bat ASC2 in mice reduced the severity of peritonitis induced by gout crystals and ASC particles. Bat ASC2 also dampened inflammation induced by multiple viruses and reduced mortality of influenza A virus infection. Importantly, it also suppressed SARS-CoV-2-immune-complex-induced inflammasome activation. Four key residues were identified for the gain of function of bat ASC2. Our results demonstrate that bat ASC2 is an important negative regulator of inflammasomes with therapeutic potential in inflammatory diseases.

Inflammasome signaling proteins as biomarkers of COVID-19.

Introduction: One of the main characteristics of COVID-19 is an exacerbated inflammatory response that results in cardiometabolic complications and dysfunction in the nervous system. Moreover, these complications may extend beyond the period of active SARS-CoV2 infection and even extend over a year. Thus, it is important to better understand the contribution of the inflammatory responses in COVID-19 patients, not just in the acute phase but also after the infection has subsided. Methods: We measured the protein levels of inflammasome signaling proteins using Simple Plex microfluidics technology in patients with an active SARS-CoV2 infection and in recovered patients to determine their potential use as biomarkers of COVID-19. We carried out statistical analyses to identify which proteins were increased in COVID-19 patients with active infection and in recovered patients. The receiver operating characteristics (ROC) were calculated for each analyte to determine their potential fit as biomarkers. Results: The inflammasome proteins caspase-1, apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC), interleukin (IL)-1ß and IL-18 were elevated in the plasma of patients with active infection and remained elevated after the infection was resolved for approximately 2 months after. Levels of caspase-1 and ASC continued to increase long after patients had recovered from the infection. Furthermore, when measuring biomarkers of inflammation during active infection, analyses with area under the curve (AUC) values above 0.75 indicated that caspase-1, ASC, IL-1ß and IL-18 are reliable biomarkers of the inflammatory response during active COVID-19 infection. Moreover, when measuring biomarkers of inflammation after recovery from active infection, caspase-1 and ASC presented AUC values above 0.9. Discussion: These findings indicate that inflammasome signaling proteins can be used to reliably monitor the inflammatory innate immune response in COVID-19 patients.

Neutrophils in Health and Disease: From Receptor Sensing to Inflammasome Activation.

Neutrophils-polymorphonuclear cells (PMNs) are the cells of the initial immune response and make up the majority of leukocytes in the peripheral blood. After activation, these cells modify their functional status to meet the needs at the site of action or according to the agent causing injury. They receive signals from their surroundings and "plan" the course of the response in both temporal and spatial contexts. PMNs dispose of intracellular signaling pathways that allow them to perform a wide range of functions associated with the development of inflammatory processes. In addition to these cells, some protein complexes, known as inflammasomes, also have a special role in the development and maintenance of inflammation. These complexes participate in the proteolytic activation of key pro-inflammatory cytokines, such as IL-1ß and IL-18. In recent years, there has been significant progress in the understanding of the structure and molecular mechanisms behind the activation of inflammasomes and their participation in the pathogenesis of numerous diseases. The available reports focus primarily on macrophages and dendritic cells. According to the literature, the activation of inflammasomes in neutrophils and the associated death type-pyroptosis-is regulated in a different manner than in other cells. The present work is a review of the latest reports concerning the course of inflammasome activation and inflammatory cytokine secretion in response to pathogens in neutrophils, as well as the role of these mechanisms in the pathogenesis of selected diseases.

Novel Translational Animal Model Of Pediatric Viral Myocarditis

Myocarditis is a heart condition characterized by inflammation of cardiac myocytes. This inflammation is instigated by the activation of both the innate and acquired immune responses and is most often caused by viruses (flu, hand foot and mouth and COVID-19). Myocarditis may progress to dilated cardiomyopathy (DCM), a chronic heart condition in which fibrosis and remodeling weakens the ability of the heart to effectively pump. Myocarditis is a leading cause of sudden death in children and young adults. In this study, we investigated the progression and severity of myocarditis within the pediatric population as compared to an adult population. Prior to this study there were no mouse models for pediatric myocarditis but a large percent of patients with myocarditis are children. We utilized our knowledge from our adult mouse model of coxsackievirus B3 (CVB3) myocarditis to create a pediatric CVB3 myocarditis model in order to better understand the development of myocarditis in children. We hypothesized that myocarditis would have sex-specific differences in the manifestation and severity similar to the adult model but the mechanisms of disease would very between ages. We utilized 4-week-old male and female BALB/c mice to model pediatric myocarditis as compared to 8-week-old mice. Mice were be infected with heart-passaged CVB3 intraperitoneally (ip) on day (d) 0. Disease severity and progression was evaluated during acute myocarditis (d8-12 pi) and during DCM (d35pi). After anesthesia, body weight, heart weight and tibia length, blood, hearts, pancreas and spleens were harvested. Echocardiography was conducted on mice at the chronic DCM timepoint. We found that adult male and female mice develop myocarditis with male mice have more severe disease and progress to DCM as compared to female mice. The main immune cells and pathways involved in myocarditis severity were macrophages, complement and the inflammasome in male adult mice. This increase in disease was driven by testosterone and reduced by estrogen as seen utilizing gonadectomies. In the pediatric population we did not see as drastic of differences in sex hormone levels as the mice are pre-pubescent, this led to less dramatic sex differences in disease and altered immune mechanisms leading to disease in the pediatric population compared to the adults. We do see induction of myocarditis in both male and female pediatric mice compared to uninfected controls but severity in the pediatric population is less than adult population. Successful development of a pediatric translational mouse model of viral myocarditis will significantly impact the myocarditis field by allowing the ability to assess differences between pediatric and adult populations and develop targeted diagnostics and treatments.Copyright © 2022

Spirulina for Protection Against COVID-19 via Regulating ACE2, FNDC5, and NLRP3: A Triple-Blind Randomized Placebo-Controlled Trial in Obese Adults

Background: Spirulina may protect individuals against viral infections and promote health in obese subjects. This study is designed to investigate the impacts of spirulina on obesity to find a hope to protect this population against COVID-19. Material(s) and Method(s): In a double-blinded randomized placebo-controlled trial, 24 obese subjects (Mean age: 44.83+/-3.04 years;mean weight: 111.95+/-22.55kg;body mass index (BMI): 40.31+/-6.03kg/m2) were randomly allocated to spirulina (n=12) or control (Co, n=12) groups. Spirulina was administered 2 gr/day for 8 weeks and the Co group received a placebo for a similar period. Before and after the administration of spirulina, the anthropometric measurements were calculated for each subject. Furthermore, ACE2, NLRP3, and FNDC5 gene expression were examined in adults with obesity. Result(s): Our findings demonstrated that spirulina could not effective in normalizing body weight (BW), BMI, and waist-hip ratio (WHR). Spirulina administration significantly upregulated the gene expression of FNDC5 and significantly reduced NLRP3 and ACE2 gene expression in obese subjects compared with the Co-group. Furthermore, by increasing FNDC5 the gene expression of NLRP3 and ACE2 was significantly reduced. Conclusion(s): While administration of spirulina for eight weeks could not affect the anthropometric measurements, it showed the greatest impact on the gene expression of NLRP3, ACE2, and FNDC5, emplacing its potential in the protection of obese cases against COVID-19.Copyright © 2023 Journal of Cellular & Molecular Anesthesia. All rights reserved.

Identifying key genes related to inflammasome in severe COVID-19 patients based on a joint model with random forest and artificial neural network.

Background: The coronavirus disease 2019 (COVID-19) has been spreading astonishingly and caused catastrophic losses worldwide. The high mortality of severe COVID-19 patients is an serious problem that needs to be solved urgently. However, the biomarkers and fundamental pathological mechanisms of severe COVID-19 are poorly understood. The aims of this study was to explore key genes related to inflammasome in severe COVID-19 and their potential molecular mechanisms using random forest and artificial neural network modeling. Methods: Differentially expressed genes (DEGs) in severe COVID-19 were screened from GSE151764 and GSE183533 via comprehensive transcriptome Meta-analysis. Protein-protein interaction (PPI) networks and functional analyses were conducted to identify molecular mechanisms related to DEGs or DEGs associated with inflammasome (IADEGs), respectively. Five the most important IADEGs in severe COVID-19 were explored using random forest. Then, we put these five IADEGs into an artificial neural network to construct a novel diagnostic model for severe COVID-19 and verified its diagnostic efficacy in GSE205099. Results: Using combining P value < 0.05, we obtained 192 DEGs, 40 of which are IADEGs. The GO enrichment analysis results indicated that 192 DEGs were mainly involved in T cell activation, MHC protein complex and immune receptor activity. The KEGG enrichment analysis results indicated that 192 GEGs were mainly involved in Th17 cell differentiation, IL-17 signaling pathway, mTOR signaling pathway and NOD-like receptor signaling pathway. In addition, the top GO terms of 40 IADEGs were involved in T cell activation, immune response-activating signal transduction, external side of plasma membrane and phosphatase binding. The KEGG enrichment analysis results indicated that IADEGs were mainly involved in FoxO signaling pathway, Toll-like receptor, JAK-STAT signaling pathway and Apoptosis. Then, five important IADEGs (AXL, MKI67, CDKN3, BCL2 and PTGS2) for severe COVID-19 were screened by random forest analysis. By building an artificial neural network model, we found that the AUC values of 5 important IADEGs were 0.972 and 0.844 in the train group (GSE151764 and GSE183533) and test group (GSE205099), respectively. Conclusion: The five genes related to inflammasome, including AXL, MKI67, CDKN3, BCL2 and PTGS2, are important for severe COVID-19 patients, and these molecules are related to the activation of NLRP3 inflammasome. Furthermore, AXL, MKI67, CDKN3, BCL2 and PTGS2 as a marker combination could be used as potential markers to identify severe COVID-19 patients.

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.

A Preliminary Study of Mild Heat Stress on Inflammasome Activation in Murine Macrophages.

Inflammation and mitochondrial-dependent oxidative stress are interrelated processes implicated in multiple neuroinflammatory disorders, including Alzheimer's disease (AD) and depression. Exposure to elevated temperature (hyperthermia) is proposed as a non-pharmacological, anti-inflammatory treatment for these disorders; however, the underlying mechanisms are not fully understood. Here we asked if the inflammasome, a protein complex essential for orchestrating the inflammatory response and linked to mitochondrial stress, might be modulated by elevated temperatures. To test this, in preliminary studies, immortalized bone-marrow-derived murine macrophages (iBMM) were primed with inflammatory stimuli, exposed to a range of temperatures (37-41.5 °C), and examined for markers of inflammasome and mitochondrial activity. We found that exposure to mild heat stress (39 °C for 15 min) rapidly inhibited iBMM inflammasome activity. Furthermore, heat exposure led to decreased ASC speck formation and increased numbers of polarized mitochondria. These results suggest that mild hyperthermia inhibits inflammasome activity in the iBMM, limiting potentially harmful inflammation and mitigating mitochondrial stress. Our findings suggest an additional potential mechanism by which hyperthermia may exert its beneficial effects on inflammatory diseases.

ADULT STILL'S DISEASE: NEW HORIZONS.

Still's disease in children (systemic juvenile idiopathic arthritis - JIA) and adult Still's disease (ASD) are considered as systemic autoinflammatory diseases of unknown etiology, which are based on similar immunopathogenetic mechanisms associated with genetically determined disorders of the mechanisms of innate immunity. ASD was first described 50 years ago by the English rheumatologist Eric George Lapthorne Bywaters. The molecular basis of ASD immunopathogenesis is the activation of innate immunity associated with NLRP3 inflammasome-dependent mechanisms of inflammation, characterized by the overproduction of "pro-inflammatory" cytokines - interleukin (IL) 1 and IL-18, inducing the synthesis of other proinflammatory inflammatory mediators. A review of new data concerning the mechanisms of immunopathology, clinical polymorphism, laboratory biomarkers and the possibilities of ASD pharmacotherapy is presented. Particular attention is paid to the prospects for the use of monoclonal antibodies to IL-1beta - canakinumab. The problems associated with the generality of clinical and laboratory disorders, pathogenetic mechanisms and pharmacotherapy of ASD and coronavirus disease 2019 (COVID-19) are considered.Copyright © 2021 Authors. All rights reserved.

ADULT STILL'S DISEASE: NEW HORIZONS.

Still's disease in children (systemic juvenile idiopathic arthritis - JIA) and adult Still's disease (ASD) are considered as systemic autoinflammatory diseases of unknown etiology, which are based on similar immunopathogenetic mechanisms associated with genetically determined disorders of the mechanisms of innate immunity. ASD was first described 50 years ago by the English rheumatologist Eric George Lapthorne Bywaters. The molecular basis of ASD immunopathogenesis is the activation of innate immunity associated with NLRP3 inflammasome-dependent mechanisms of inflammation, characterized by the overproduction of "pro-inflammatory" cytokines - interleukin (IL) 1 and IL-18, inducing the synthesis of other proinflammatory inflammatory mediators. A review of new data concerning the mechanisms of immunopathology, clinical polymorphism, laboratory biomarkers and the possibilities of ASD pharmacotherapy is presented. Particular attention is paid to the prospects for the use of monoclonal antibodies to IL-1beta - canakinumab. The problems associated with the generality of clinical and laboratory disorders, pathogenetic mechanisms and pharmacotherapy of ASD and coronavirus disease 2019 (COVID-19) are considered.Copyright © 2021 Authors. All rights reserved.