Severe COVID-19: NLRP3 Inflammasome Dysregulated

Illuminating the pathogenic role of SARS-CoV-2: Insights into competing endogenous RNAs (ceRNAs) regulatory networks

The appearance of SARS-CoV-2 in 2019 triggered a significant economic and health crisis worldwide, with heterogeneous molecular mechanisms that contribute to its development are not yet fully understood. Although substantial progress has been made in elucidating the mechanisms behind SARS-CoV-2 infection and therapy, it continues to rank among the top three global causes of mortality due to infectious illnesses. Non-coding RNAs (ncRNAs), being integral components across nearly all biological processes, demonstrate effective importance in viral pathogenesis. Regarding viral infections, ncRNAs have demonstrated their ability to modulate host reactions, viral replication, and host-pathogen interactions. However, the complex interactions of different types of ncRNAs in the progression of COVID-19 remains understudied. In recent years, a novel mechanism of post-transcriptional gene regulation known as "competing endogenous RNA (ceRNA)" has been proposed. Long non-coding RNAs (lncRNAs), circular RNAs (circRNAs), and viral ncRNAs function as ceRNAs, influencing the expression of associated genes by sequestering shared microRNAs. Recent research on SARS-CoV-2 has revealed that disruptions in specific ceRNA regulatory networks (ceRNETs) contribute to the abnormal expression of key infection-related genes and the establishment of distinctive infection characteristics. These findings present new opportunities to delve deeper into the underlying mechanisms of SARS-CoV-2 pathogenesis, offering potential biomarkers and therapeutic targets. This progress paves the way for a more comprehensive understanding of ceRNETs, shedding light on the intricate mechanisms involved. Further exploration of these mechanisms holds promise for enhancing our ability to prevent viral infections and develop effective antiviral treatments.

Immune responses in COVID-19 patients: Insights into cytokine storms and adaptive immunity kinetics

SARS-CoV-2 infection can trigger cytokine storm in some patients, which characterized by an excessive production of cytokines and chemical mediators. This hyperactive immune response may cause significant tissue damage and multiple organ failure (MOF). The severity of COVID-19 correlates with the intensity of cytokine storm, involving elements such as IFN, NF-κB, IL-6, HMGB1, etc. It is imperative to rapidly engage adaptive immunity to effectively control the disease progression. CD4+ T cells facilitate an immune response by improving B cells in the production of neutralizing antibodies and activating CD8+ T cells, which are instrumental in eradicating virus-infected cells. Meanwhile, antibodies from B cells can neutralize virus, obstructing further infection of host cells. In individuals who have recovered from the disease, virus-specific antibodies and memory T cells were observed, which could confer a level of protection, reducing the likelihood of re-infection or attenuating severity. This paper discussed the roles of macrophages, IFN, IL-6 and HMGB1 in cytokine release syndrome (CRS), the intricacies of adaptive immunity, and the persistence of immune memory, all of which are critical for the prevention and therapeutic strategies against COVID-19.

Taming the storm: potential anti-inflammatory compounds targeting SARS-CoV-2 MPro

In severe COVID-19 cases, an exacerbated inflammatory response triggers a cytokine storm that can worsen the prognosis. Compounds with both antiviral and anti-inflammatory activities show promise as candidates for COVID-19 therapy, as they potentially act against the SARS-CoV-2 infection regardless of the disease stage. One of the most attractive drug targets among coronaviruses is the main protease (MPro). This enzyme is crucial for cleaving polyproteins into non-structural proteins required for viral replication. The aim of this review was to identify SARS-CoV-2 MPro inhibitors with both antiviral and anti-inflammatory properties. The interactions of the compounds within the SARS-CoV-2 MPro binding site were analyzed through molecular docking when data from crystallographic structures were unavailable. 18 compounds were selected and classified into five different superclasses. Five of them exhibit high potency against MPro: GC-376, baicalein, naringenin, heparin, and carmofur, with IC50 values below 0.2 μM. The MPro inhibitors selected have the potential to alleviate lung edema and decrease cytokine release. These molecules mainly target three critical inflammatory pathways: NF-κB, JAK/STAT, and MAPK, all previously associated with COVID-19 pathogenesis. The structures of the compounds occupy the S1/S2 substrate binding subsite of the MPro. They interact with residues from the catalytic dyad (His41 and Cys145) and/or with the oxyanion hole (Gly143, Ser144, and Cys145), which are pivotal for substrate recognition. The MPro SARS-CoV-2 inhibitors with potential anti-inflammatory activities present here could be optimized for maximum efficacy and safety and be explored as potential treatment of both mild and severe COVID-19.

The Role of the Nrf2 Pathway in Airway Tissue Damage Due to Viral Respiratory Infections

Respiratory viruses constitute a significant cause of illness and death worldwide. Respiratory virus-associated injuries include oxidative stress, ferroptosis, inflammation, pyroptosis, apoptosis, fibrosis, autoimmunity, and vascular injury. Several studies have demonstrated the involvement of the nuclear factor erythroid 2-related factor 2 (Nrf2) in the pathophysiology of viral infection and associated complications. It has thus emerged as a pivotal player in cellular defense mechanisms against such damage. Here, we discuss the impact of Nrf2 activation on airway injuries induced by respiratory viruses, including viruses, coronaviruses, rhinoviruses, and respiratory syncytial viruses. The inhibition or deregulation of Nrf2 pathway activation induces airway tissue damage in the presence of viral respiratory infections. In contrast, Nrf2 pathway activation demonstrates protection against tissue and organ injuries. Clinical trials involving Nrf2 agonists are needed to define the effect of Nrf2 therapeutics on airway tissues and organs damaged by viral respiratory infections.

Post-COVID-19 condition: a sex-based analysis of clinical and laboratory trends

Background and aim

Post-COVID-19 condition (PCC) encompasses long-lasting symptoms in individuals with COVID-19 and is estimated to affect between 31-67% of patients, with women being more commonly affected. No definitive biomarkers have emerged in the acute stage that can help predict the onset of PCC, therefore we aimed at describing sex-disaggregated data of PCC patients from a local cohort and explore potential acute predictors of PCC and neurologic PCC.

Methods

A local cohort of consecutive patients admitted with COVID-19 diagnosis between June 2020 and July 2021 were registered, and clinical and laboratory data were recorded. Only those <65 years, discharged alive and followed up at 6 and 12 months after admission were considered in these analyses. Multivariable logistic regression analysis was performed to explore variables associated with PCC (STATA v 18.0).

Results

From 130 patients in the cohort, 104 were contacted: 30% were women, median age of 42 years. At 6 months, 71 (68%) reported PCC symptoms. Women exhibited a higher prevalence of any PCC symptom (87 vs. 60%, p = 0.007), lower ferritin (p = 0.001) and procalcitonin (p = 0.021) and higher TNF levels (p = 0.042) in the acute phase compared to men. Being women was independently associated to 7.60 (95% CI 1.27-45.18, p = 0.026) higher risk for PCC. Moreover, women had lower return to normal activities 6 and 12 months.

Conclusion

Our findings highlight the lasting impact of COVID-19, particularly in young women, emphasising the need for tailored post-COVID care. The lower ferritin levels in women are an intriguing observation, warranting further research. The study argues for comprehensive strategies that address sex-specific challenges in recovery from COVID-19.

Effect and mechanism of quercetin or quercetin-containing formulas against COVID-19: From bench to bedside

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused the global coronavirus disease 2019 (COVID-19) pandemic since 2019. Immunopathogenesis and thromboembolic events are central to its pathogenesis. Quercetin exhibits several beneficial activities against COVID-19, including antiviral, anti-inflammatory, immunomodulatory, antioxidative, and antithrombotic effects. Although several reviews have been published, these reviews are incomplete from the viewpoint of translational medicine. The authors comprehensively evaluated the evidence of quercetin against COVID-19, both basically and clinically, to apply quercetin and/or its derivatives in the future. The authors searched the PubMed, Embase, and the Cochrane Library databases without any restrictions. The search terms included COVID-19, SARS-CoV-2, quercetin, antiviral, anti-inflammatory, immunomodulatory, thrombosis, embolism, oxidative, and microbiota. The references of relevant articles were also reviewed. All authors independently screened and reviewed the quality of each included manuscript. The Cochrane Risk of Bias Tool, version 2 (RoB 2) was used to assess the quality of the included randomized controlled trials (RCTs). All selected studies were discussed monthly. The effectiveness of quercetin against COVID-19 is not solid due to methodological flaws in the clinical trials. High-quality studies are also required for quercetin-containing traditional Chinese medicines. The low bioavailability and highly variable pharmacokinetics of quercetin hinder its clinical applications. Its positive impact on immunomodulation through reverting dysbiosis of gut microbiota still lacks robust evidence. Quercetin against COVID-19 does not have tough clinical evidence. Strategies to improve its bioavailability and/or to develop its effective derivatives are needed. Well-designed RCTs are also crucial to confirm their effectiveness in the future.

NLRP inflammasomes in health and disease

NLRP inflammasomes are a group of cytosolic multiprotein oligomer pattern recognition receptors (PRRs) involved in the recognition of pathogen-associated molecular patterns (PAMPs) and danger-associated molecular patterns (DAMPs) produced by infected cells. They regulate innate immunity by triggering a protective inflammatory response. However, despite their protective role, aberrant NLPR inflammasome activation and gain-of-function mutations in NLRP sensor proteins are involved in occurrence and enhancement of non-communicating autoimmune, auto-inflammatory, and neurodegenerative diseases. In the last few years, significant advances have been achieved in the understanding of the NLRP inflammasome physiological functions and their molecular mechanisms of activation, as well as therapeutics that target NLRP inflammasome activity in inflammatory diseases. Here, we provide the latest research progress on NLRP inflammasomes, including NLRP1, CARD8, NLRP3, NLRP6, NLRP7, NLRP2, NLRP9, NLRP10, and NLRP12 regarding their structural and assembling features, signaling transduction and molecular activation mechanisms. Importantly, we highlight the mechanisms associated with NLRP inflammasome dysregulation involved in numerous human auto-inflammatory, autoimmune, and neurodegenerative diseases. Overall, we summarize the latest discoveries in NLRP biology, their forming inflammasomes, and their role in health and diseases, and provide therapeutic strategies and perspectives for future studies about NLRP inflammasomes.

The association between high mobility group box 1 (HMGB1) and Interleukin-18 (IL-18) serum concentrations in COVID-19 inpatients

Background

High mobility group box 1 (HMGB1) and interleukin-18 (IL-18) are involved in various non-coronavirus disease pathogenesis and are reported as potential biomarkers for coronavirus disease (COVID-19). However, their association with COVID-19 pathogenesis has not yet been explored.

Aim

This study aimed to investigate the association between HMGB1 and IL-18 concentrations in the sera of COVID-19 patients versus non-COVID-19 patients.

Material and methods

We used stored serum samples obtained from 30 COVID-19 patients and 30 non-COVID-19 patients. We collected data on age, gender, treatment status, principal diagnosis, and comorbidity from patient medical records. HMGB1 and IL-18 concentrations were analyzed in the serum by enzyme-linked immunosorbent assay (ELISA). The swab samples' RT-PCR cycle threshold (CT) values were obtained from the laboratory database.

Results

HMGB1 concentrations were increased in the COVID-19 inpatients and non-COVID-19 inpatients compared to non-COVID-19 outpatients (COVID-19 inpatients vs. non-COVID-19 outpatients: 151.33 (90.27-192.38) vs. 80.75 (54.16-128.72) ng/ml; p = 0.0316; non-COVID-19 inpatients vs. non-COVID-19 outpatients: 152.66 (104.04-288.51) vs. 80.75 (54.16-128.72) ng/ml; p = 0.0199). IL-18 concentrations were also higher in the COVID-19 inpatients and non-COVID-19 inpatients compared to non-COVID-19 outpatients (COVID-19 inpatients vs. non-COVID-19 outpatients: 620.00 (461.50-849.6) vs. 403.10 (372.70-556.90) pg/ml; p = 0.0376; non-COVID-19 inpatients vs. non-COVID-19 outpatients: 835.70 (558.30-1602.00) vs. 403.10 (372.70-556.90) pg/ml; p = 0.0026). Moreover, HMGB1 was associated with IL-18 concentrations in the sera of COVID-19 inpatients (p = 0.0337; r = 0.5500).

Conclusion

The association of HMGB1 and IL-18 in COVID-19 might indicate the potential for a dangerous cycle leading to a cytokine storm to occur.

Self-DNA driven inflammation in COVID-19 and after mRNA-based vaccination: lessons for non-COVID-19 pathologies

The coronavirus disease 2019 (COVID-19) pandemic triggered an unprecedented concentration of economic and research efforts to generate knowledge at unequalled speed on deregulated interferon type I signalling and nuclear factor kappa light chain enhancer in B-cells (NF-κB)-driven interleukin (IL)-1β, IL-6, IL-18 secretion causing cytokine storms. The translation of the knowledge on how the resulting systemic inflammation can lead to life-threatening complications into novel treatments and vaccine technologies is underway. Nevertheless, previously existing knowledge on the role of cytoplasmatic or circulating self-DNA as a pro-inflammatory damage-associated molecular pattern (DAMP) was largely ignored. Pathologies reported 'de novo' for patients infected with Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV)-2 to be outcomes of self-DNA-driven inflammation in fact had been linked earlier to self-DNA in different contexts, e.g., the infection with Human Immunodeficiency Virus (HIV)-1, sterile inflammation, and autoimmune diseases. I highlight particularly how synergies with other DAMPs can render immunogenic properties to normally non-immunogenic extracellular self-DNA, and I discuss the shared features of the gp41 unit of the HIV-1 envelope protein and the SARS-CoV 2 Spike protein that enable HIV-1 and SARS-CoV-2 to interact with cell or nuclear membranes, trigger syncytia formation, inflict damage to their host's DNA, and trigger inflammation - likely for their own benefit. These similarities motivate speculations that similar mechanisms to those driven by gp41 can explain how inflammatory self-DNA contributes to some of most frequent adverse events after vaccination with the BNT162b2 mRNA (Pfizer/BioNTech) or the mRNA-1273 (Moderna) vaccine, i.e., myocarditis, herpes zoster, rheumatoid arthritis, autoimmune nephritis or hepatitis, new-onset systemic lupus erythematosus, and flare-ups of psoriasis or lupus. The hope is to motivate a wider application of the lessons learned from the experiences with COVID-19 and the new mRNA vaccines to combat future non-COVID-19 diseases.

Protective effects of IL18-105G > A and IL18-137C > Ggenetic variants on severity of COVID-19

OBJECTIVE AND DESIGN

A cross-sectional study evaluated the IL18-105G > A (rs360717) and IL18-137C > G (rs187238) variants on Coronavírus Disease 2019 (COVID-19) severity.

SUBJECTS AND METHODS

528 patients with COVID-19 classifed with mild (n = 157), moderate (n = 63) and critical (n = 308) disease were genotpyed for the IL18-105G > A and IL18-137C > G variants.

RESULTS

We observed associations between severe + critical COVID-19 groups (reference group was mild COVID-19) and the IL18-105G > A (p = 0.008) and IL18-137C > G (p = 0.01) variants, which remained significant after adjusting for sex, ethnicity and age. Consequently, we have examined the associations between moderate + critical COVID-19 and the genotypes of both variants using different genetic models. The IL18-105G > A was associated with severe disease (moderate + critical), with effects of the GA genotype in the codominant [Odds ratio (OR), (95 % confidence interval) 0.55, 0.34-0.89, p = 0.015], overdominant (0.56, 0.35-0.89, p = 0.014) and dominant (0.60, 0.38-0.96, p = 0.031) models. IL18-105 GA coupled with age, chest computed tomograhy scan anormalities, body mass index, heart diseases, type 2 diabetes mellitus, hypertension, and inflammation may be used to predict the patients who develop severe disease with an accuracy of 84.3 % (sensitivity: 83.3 % and specificity: 86.5 %). Therefore, the presence of the IL18-105 A allele in homozygosis or heterozygosis conferred about 44.0 % of protection in the development of moderate and severe COVID-19. The IL18-137C > G variant was also associated with protective effects in the codominant (0.55, 0.34-0.89, p = 0.015), overdominant (0.57, 0.36-0.91, p = 0.018), and dominant models (0.59, 0.37-0.93, p = 0.025). Therefore, the IL18-137 G allele showed a protective effect against COVID-19 severity.

CONCLUSION

The IL18-105G > A and IL18-137C > Gvariants may contribute with protective effects for COVID-19 severity and the effects of IL18-137C > G may be modulating IL-18 production and Th1-mediated immune responses.

Investigating the Nexus of NLRP3 Inflammasomes and COVID-19 Pathogenesis: Unraveling Molecular Triggers and Therapeutic Strategies

The coronavirus disease 2019 (COVID-19) global pandemic, caused by severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2), has been marked by severe cases demonstrating a "cytokine storm", an upsurge of pro-inflammatory cytokines in the bloodstream. NLRP3 inflammasomes, integral to the innate immune system, are speculated to be activated by SARS-CoV-2 within host cells. This review investigates the potential correlation between NLRP3 inflammasomes and COVID-19, exploring the cellular and molecular mechanisms through which SARS-CoV-2 triggers their activation. Furthermore, promising strategies targeting NLRP3 inflammasomes are proposed to mitigate the excessive inflammatory response provoked by SARS-CoV-2 infection. By synthesizing existing studies, this paper offers insights into NLRP3 as a therapeutic target, elucidating the interplay between COVID-19 and its pathophysiology. It serves as a valuable reference for future clinical approaches in addressing COVID-19 by targeting NLRP3, thus providing potential avenues for therapeutic intervention.

SARS-CoV-2 S protein activates NLRP3 inflammasome and deregulates coagulation factors in endothelial and immune cells

BACKGROUND

Hyperinflammation, hypercoagulation and endothelial injury are major findings in acute and post-COVID-19. The SARS-CoV-2 S protein has been detected as an isolated element in human tissues reservoirs and is the main product of mRNA COVID-19 vaccines. We investigated whether the S protein alone triggers pro-inflammatory and pro-coagulant responses in primary cultures of two cell types deeply affected by SARS-CoV-2, such are monocytes and endothelial cells.

METHODS

In human umbilical vein endothelial cells (HUVEC) and monocytes, the components of NF-κB and the NLRP3 inflammasome system, as well as coagulation regulators, were assessed by qRT-PCR, Western blot, flow cytometry, or indirect immunofluorescence.

RESULTS

S protein activated NF-κB, promoted pro-inflammatory cytokines release, and triggered the priming and activation of the NLRP3 inflammasome system resulting in mature IL-1β formation in both cell types. This was paralleled by enhanced production of coagulation factors such as von Willebrand factor (vWF), factor VIII or tissue factor, that was mediated, at least in part, by IL-1β. Additionally, S protein failed to enhance ADAMTS-13 levels to counteract the pro-coagulant activity of vWF multimers. Monocytes and HUVEC barely expressed angiotensin-converting enzyme-2. Pharmacological approaches and gene silencing showed that TLR4 receptors mediated the effects of S protein in monocytes, but not in HUVEC.

CONCLUSION

S protein behaves both as a pro-inflammatory and pro-coagulant stimulus in human monocytes and endothelial cells. Interfering with the receptors or signaling pathways evoked by the S protein may help preventing immune and vascular complications driven by such an isolated viral element. Video Abstract.

SARS-CoV-2 ORF3a Protein as a Therapeutic Target against COVID-19 and Long-Term Post-Infection Effects

The COVID-19 pandemic caused by SARS-CoV-2 has posed unparalleled challenges due to its rapid transmission, ability to mutate, high mortality and morbidity, and enduring health complications. Vaccines have exhibited effectiveness, but their efficacy diminishes over time while new variants continue to emerge. Antiviral medications offer a viable alternative, but their success has been inconsistent. Therefore, there remains an ongoing need to identify innovative antiviral drugs for treating COVID-19 and its post-infection complications. The ORF3a (open reading frame 3a) protein found in SARS-CoV-2, represents a promising target for antiviral treatment due to its multifaceted role in viral pathogenesis, cytokine storms, disease severity, and mortality. ORF3a contributes significantly to viral pathogenesis by facilitating viral assembly and release, essential processes in the viral life cycle, while also suppressing the body's antiviral responses, thus aiding viral replication. ORF3a also has been implicated in triggering excessive inflammation, characterized by NF-κB-mediated cytokine production, ultimately leading to apoptotic cell death and tissue damage in the lungs, kidneys, and the central nervous system. Additionally, ORF3a triggers the activation of the NLRP3 inflammasome, inciting a cytokine storm, which is a major contributor to the severity of the disease and subsequent mortality. As with the spike protein, ORF3a also undergoes mutations, and certain mutant variants correlate with heightened disease severity in COVID-19. These mutations may influence viral replication and host cellular inflammatory responses. While establishing a direct link between ORF3a and mortality is difficult, its involvement in promoting inflammation and exacerbating disease severity likely contributes to higher mortality rates in severe COVID-19 cases. This review offers a comprehensive and detailed exploration of ORF3a's potential as an innovative antiviral drug target. Additionally, we outline potential strategies for discovering and developing ORF3a inhibitor drugs to counteract its harmful effects, alleviate tissue damage, and reduce the severity of COVID-19 and its lingering complications.

Macrophage Activation Syndrome in Coinciding Pandemics of Obesity and COVID-19: Worse than Bad

Epigenetic changes have long-lasting impacts, which influence the epigenome and are maintained during cell division. Thus, human genome changes have required a very long timescale to become a major contributor to the current obesity pandemic. Whereas bidirectional effects of coronavirus disease 2019 (COVID-19) and obesity pandemics have given the opportunity to explore, how the viral microribonucleic acids (miRNAs) use the human's transcriptional machinery that regulate gene expression at a posttranscriptional level. Obesity and its related comorbidity, type 2 diabetes (T2D), and new-onset diabetes due to severe acute respiratory syndrome-related coronavirus 2 (SARS-CoV-2) are additional risk factors, which increase the severity of COVID-19 and its related mortality. The higher mortality rate of these patients is dependent on severe cytokine storm, which is the sum of the additional cytokine production by concomitant comorbidities and own cytokine synthesis of COVID-19. Patients with obesity facilitate the SARS-CoV-2 entry to host cell via increasing the host's cell receptor expression and modifying the host cell proteases. After entering the host cells, the SARS-CoV-2 genome directly functions as a messenger ribonucleic acid (mRNA) and encodes a set of nonstructural proteins via processing by the own proteases, main protease (Mpro), and papain-like protease (PLpro) to initiate viral genome replication and transcription. Following viral invasion, SARS-CoV-2 infection reduces insulin secretion via either inducing β-cell apoptosis or reducing intensity of angiotensin-converting enzyme 2 (ACE2) receptors and leads to new-onset diabetes. Since both T2D and severity of COVID-19 are associated with the increased serum levels of pro-inflammatory cytokines, high glucose levels in T2D aggravate SARS-CoV-2 infection. Elevated neopterin (NPT) value due to persistent interferon gamma (IFN-γ)-mediated monocyte-macrophage activation is an indicator of hyperactivated pro-inflammatory phenotype M1 macrophages. Thus, NPT could be a reliable biomarker for the simultaneously occurring COVID-19-, obesity- and T2D-induced cytokine storm. While host miRNAs attack viral RNAs, viral miRNAs target host transcripts. Eventually, the expression rate and type of miRNAs also are different in COVID-19 patients with different viral loads. It is concluded that specific miRNA signatures in macrophage activation phase may provide an opportunity to become aware of the severity of COVID-19 in patients with obesity and obesity-related T2D.

The purinergic receptor P2X7 and the NLRP3 inflammasome are druggable host factors required for SARS-CoV-2 infection

Purinergic receptors and NOD-like receptor protein 3 (NLRP3) inflammasome regulate inflammation and viral infection, but their effects on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection remain poorly understood. Here, we report that the purinergic receptor P2X7 and NLRP3 inflammasome are cellular host factors required for SARS-CoV-2 infection. Lung autopsies from patients with severe coronavirus disease 2019 (COVID-19) reveal that NLRP3 expression is increased in host cellular targets of SARS-CoV-2 including alveolar macrophages, type II pneumocytes and syncytia arising from the fusion of infected macrophages, thus suggesting a potential role of NLRP3 and associated signaling pathways to both inflammation and viral replication. In vitro studies demonstrate that NLRP3-dependent inflammasome activation is detected upon macrophage abortive infection. More importantly, a weak activation of NLRP3 inflammasome is also detected during the early steps of SARS-CoV-2 infection of epithelial cells and promotes the viral replication in these cells. Interestingly, the purinergic receptor P2X7, which is known to control NLRP3 inflammasome activation, also favors the replication of D614G and alpha SARS-CoV-2 variants. Altogether, our results reveal an unexpected relationship between the purinergic receptor P2X7, the NLRP3 inflammasome and the permissiveness to SARS-CoV-2 infection that offers novel opportunities for COVID-19 treatment.

Cathepsins and SARS-CoV-2 infection: From pathogenic factors to potential therapeutic targets

Coronavirus disease-19 (COVID-19) is caused by severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) infection. The COVID-19 pandemic began in March 2020 and has wrought havoc on health and economic systems worldwide. Efficacious treatment for COVID-19 is lacking: Only preventive measures as well as symptomatic and supportive care are available. Preclinical and clinical studies have indicated that lysosomal cathepsins might contribute to the pathogenesis and disease outcome of COVID-19. Here, we discuss cutting-edge evidence on the pathological roles of cathepsins in SARS-CoV-2 infection, host immune dysregulations, and the possible underlying mechanisms. Cathepsins are attractive drug targets because of their defined substrate-binding pockets, which can be exploited as binding sites for pharmaceutical enzyme inhibitors. Accordingly, the potential modulatory strategies of cathepsin activity are discussed. These insights could shed light on the development of cathepsin-based interventions for COVID-19.

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.

Evaluation of the relationship between serum interleukin-1β levels and expression of inflammasome-related genes in patients with COVID-19

BACKGROUND

Inflammasomes are a group of molecules that are strongly involved in causing inflammation. This study aimed to evaluate the expression of NLR family pyrin domain containing 1 (NLRP1), NLRP3, and Apoptosis-associated speck-like protein containing a CARD (ASC) as well as their association with serum level of interleukin (IL)-1β in patients with coronavirus disease 2019 (COVID-19).

METHODS

Thirty COVID-19 patients and 30 healthy subjects (HS) were recruited. Peripheral blood specimens were collected from subjects to assess NLRP1, NLRP3, and ASC gene expression by Real time-PCR technique. Serum levels of IL-1β were also measured via the enzyme-linked immunosorbent assay (ELISA).

RESULTS

The findings showed no significant differences in serum IL-1β level between COVID-19 patients and the HS group. mRNA expression of ASC (P = 0.008) and NLRP1 (P = 0.03) gene had a significant increase in COVID-19 patients compared to HS, while there was no significant increase in the expression of NLRP3 between the studied group. There were significant correlations between patient's data and expression levels of NLRP1, NLRP3, IL-1β, and ACS.

CONCLUSIONS

NLRP1 and ASC may have a more critical role in the generation of the active form of IL-1β in COVID-19 patients compared to NLRP3. However, serum levels of IL-1β in patients did not show a significant increase, which may be due to the patient's condition and the application of virus escape mechanisms through impaired NLRP3 expression and its malfunction.

Protective Effects of Proanthocyanidin-Rich Fraction from Red Rice Germ and Bran on Lung Cell Inflammation via Inhibition of NF-κB/NLRP3 Inflammasome Pathway

The activation of the NLRP3 inflammasome pathway during infectious pathogen-induced immunopathology can lead to chronic inflammation and various adverse health outcomes. Identification of functional foods with anti-inflammatory properties is crucial for preventing inflammation triggered by NLRP3 inflammasome activation. This study aimed to investigate the anti-inflammatory properties of a proanthocyanidin-rich fraction obtained from red rice germ and bran against lipopolysaccharide (LPS) and adenosine triphosphate (ATP)-induced condition in A549 lung cells. The proanthocyanidin-rich fraction from Yamuechaebia 3 red rice extract (YM3-PRF) was obtained using column chromatography with Sephadex LH20, and its total proanthocyanidin content was determined to be 351.43 ± 1.18 mg/g extract using the vanillin assay. A549 lung cells were pretreated with YM3-PRF at concentrations of 5-20 μg/mL prior to exposure to LPS (1 μg/mL) and ATP (5 nM). The results showed that YM3-PRF significantly inhibited the expression of inflammatory mRNAs (NLRP3, IL-6, IL-1β, and IL-18) and the secretion of cytokines (IL-6, IL-1β, and IL-18) in a dose-dependent manner (p < 0.05). Mechanistically, YM3-PRF exerted its anti-inflammatory effects by inhibiting NF-κB translocation and downregulating proteins associated with the NLRP3 inflammasome pathway (NLRP3, ASC, pro-caspase-1, and cleaved-caspase-1). These findings suggest that the proanthocyanidin-rich fraction from red rice germ and bran has protective effects and may serve as a potential therapeutic option for chronic inflammatory diseases associated with NLRP3 inflammasome activation.

Molecular mechanisms of COVID-19-induced pulmonary fibrosis and epithelial-mesenchymal transition

As the outbreak of COVID-19 caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) first broke out in Hubei Province, China, at the end of 2019. It has brought great challenges and harms to global public health. SARS-CoV-2 mainly affects the lungs and is mainly manifested as pulmonary disease. However, one of the biggest crises arises from the emergence of COVID-19-induced fibrosis. At present, there are still many questions about how COVID-19 induced pulmonary fibrosis (PF) occurs and how to treat and regulate its long-term effects. In addition, as an important process of fibrosis, the effect of COVID-19 on epithelial-mesenchymal transition (EMT) may be an important factor driving PF. This review summarizes the main pathogenesis and treatment mechanisms of COVID-19 related to PF. Starting with the basic mechanisms of PF, such as EMT, transforming growth factor-β (TGF-β), fibroblasts and myofibroblasts, inflammation, macrophages, innate lymphoid cells, matrix metalloproteinases and tissue inhibitors of metalloproteinases, hedgehog pathway as well as Notch signaling. Further, we highlight the importance of COVID-19-induced EMT in the process of PF and provide an overview of the related molecular mechanisms, which will facilitate future research to propose new clinical therapeutic solutions for the treatment of COVID-19-induced PF.

Vincamine as an agonist of G protein-coupled receptor 40 effectively ameliorates pulmonary fibrosis in mice

BACKGROUND

Pulmonary fibrosis (PF) is an irreversible and fatal lung disease with limited therapeutic options. G protein-coupled receptor 40 (GPR40) has been developed as a promising therapeutic target for metabolic disorders and functions potently in varied pathological and physiological processes. Vincamine (Vin) is a monoterpenoid indole alkaloid originated from Madagascar periwinkle and was reported as a GPR40 agonist in our previous work.

PURPOSE

Here, we aimed to clarify the role of GPR40 in PF pathogenesis by using the determined GPR40 agonist Vin as a probe and explore the potential of Vin in ameliorating PF in mice.

METHODS

Pulmonary GPR40 expression alterations were assessed in both PF patients and bleomycin-induced PF mice (PF mice). Vin was used to evaluate the therapeutic potential of GPR40 activation for PF and the underlying mechanism was intensively investigated by assays against GPR40 knockout (Ffar1^-/-) mice and the cells transfected with si-GPR40 in vitro.

RESULTS

Pulmonary GPR40 expression level was highly downregulated in PF patients and PF mice. Pulmonary GPR40 deletion (Ffar1^-/-) exacerbated pulmonary fibrosis as evidenced by the increases in mortality, dysfunctional lung index, activated myofibroblasts and extracellular matrix (ECM) deposition in PF mice. Vin-mediated pulmonary GPR40 activation ameliorated PF-like pathology in mice. Mechanistically, Vin suppressed ECM deposition by GPR40/β-arrestin2/SMAD3 pathway, repressed inflammatory response by GPR40/NF-κB/NLRP3 pathway and inhibited angiogenesis by decreasing GPR40-mediated vascular endothelial growth factor (VEGF) expression in the region of interface to normal parenchyma in pulmonary fibrotic tissues of mice.

CONCLUSION

Pulmonary GPR40 activation shows promise as a therapeutic strategy for PF and Vin exhibits high potential in treating this disease.

The role of HMGB1 in COVID-19-induced cytokine storm and its potential therapeutic targets: A review

Hyperinflammation characterized by elevated proinflammatory cytokines known as 'cytokine storms' is the major cause of high severity and mortality seen in COVID-19 patients. The pathology behind the cytokine storms is currently unknown. Increased HMGB1 levels in serum/plasma of COVID-19 patients were reported by many studies, which positively correlated with the level of proinflammatory cytokines. Dead cells following SARS-CoV-2 infection might release a large amount of HMGB1 and RNA of SARS-CoV-2 into extracellular space. HMGB1 is a well-known inflammatory mediator. Additionally, extracellular HMGB1 might interact with SARS-CoV-2 RNA because of its high capability to bind with a wide variety of molecules including nucleic acids and could trigger massive proinflammatory immune responses. This review aimed to critically explore the many possible pathways by which HMGB1-SARS-CoV-2 RNA complexes mediate proinflammatory responses in COVID-19. The contribution of these pathways to impair host immune responses against SARS-CoV-2 infection leading to a cytokine storm was also evaluated. Moreover, since blocking the HMGB1-SARS-CoV-2 RNA interaction might have therapeutic value, some of the HMGB1 antagonists have been reviewed. The HMGB1- SARS-CoV-2 RNA complexes might trigger endocytosis via RAGE which is linked to lysosomal rupture, PRRs activation, and pyroptotic death. High levels of the proinflammatory cytokines produced might suppress many immune cells leading to uncontrolled viral infection and cell damage with more HMGB1 released. Altogether these mechanisms might initiate a proinflammatory cycle leading to a cytokine storm. HMGB1 antagonists could be considered to give benefit in alleviating cytokine storms and serve as a potential candidate for COVID-19 therapy.

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.

Rescuing fertility during COVID-19 infection: exploring potential pharmacological and natural therapeutic approaches for comorbidity, by focusing on NLRP3 inflammasome mechanism

The respiratory system was primarily considered the only organ affected by Coronavirus disease 2019 (COVID-19). As the pandemic continues, there is an increasing concern from the scientific community about the future effects of the virus on male and female reproductive organs, infertility, and, most significantly, its impact on the future generation. The general presumption is that if the primary clinical symptoms of COVID-19 are not controlled, we will face several challenges, including compromised infertility, infection-exposed cryopreserved germ cells or embryos, and health complications in future generations, likely connected to the COVID-19 infections of parents and ancestors. In this review article, we dedicatedly studied severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) virology, its receptors, and the effect of the virus to induce the activation of inflammasome as the main arm of the innate immune response. Among inflammasomes, nucleotide oligomerization domain-like receptor protein, pyrin domain containing 3 (NLRP3) inflammasome pathway activation is partly responsible for the inflicted damages in both COVID-19 infection and some reproductive disorders, so the main focus of the discussion is on NLRP3 inflammasome in the pathogenesis of COVID-19 infection alongside in the reproductive biology. In addition, the potential effects of the virus on male and female gonad functions were discussed, and we further explored the potential natural and pharmacological therapeutic approaches for comorbidity via NLRP3 inflammasome neutralization to develop a hypothesis for averting the long-term repercussions of COVID-19. Since activation of the NLRP3 inflammasome pathway contributes to the damage caused by COVID-19 infection and some reproductive disorders, NLRP3 inflammasome inhibitors have a great potential to be considered candidates for alleviating the pathological effects of the COVID-19 infection on the germ cells and reproductive tissues. This would impede the subsequent massive wave of infertility that may threaten the patients.

COVID-19 Associated Vasculitis Confirmed by the Tissues RT-PCR: A Case Series Report

Background: Several cases of skin and central nervous system vasculopathy associated with COVID-19 in children have been published, but the information is rather limited. Our study aimed to describe these cases of vasculitis associated with COVID-19 in children. Methods: In the retrospective-prospective case series study we included information regarding four children with COVID-19-associated vasculitis. In every case, we had a morphological description and the etiology was confirmed via real-time polymerase chain reaction during a tissue biopsy. Results: The most involved systems were skin (4/4), respiratory (3/4), cardiovascular (2/4), nervous (1/4), eye (1/4), kidney (1/4), and inner year (1/4). All patients had increased inflammatory markers and thrombotic parameters (D-dimer). No patient met the criteria for multisystem inflammatory syndrome in children. Two patients met polyarteritis nodosa criteria, one met Henoch–Schonlein purpura criteria, and one met unclassified vasculitis criteria. All patients were treated with systemic glucocorticosteroids (two-pulse therapy). Non-biologic DMARDs were prescribed in all cases; 1/4 patients (25%) was treated with intravenous immunoglobuline, and 3/4 (75%) were treated with biologics (etanercept, tocilizumab, and adalimumab). Conclusions: Vasculitis associated with COVID-19 could be a life-threatening condition; SARS-CoV-2 might be a new trigger or etiological agent for vasculitis and other immune-mediated diseases. Further research and collection of similar cases are required.

SARS-CoV-2 spike protein induces IL-18-mediated cardiopulmonary inflammation via reduced mitophagy

Cardiopulmonary complications are major drivers of mortality caused by the SARS-CoV-2 virus. Interleukin-18, an inflammasome-induced cytokine, has emerged as a novel mediator of cardiopulmonary pathologies but its regulation via SARS-CoV-2 signaling remains unknown. Based on a screening panel, IL-18 was identified amongst 19 cytokines to stratify mortality and hospitalization burden in patients hospitalized with COVID-19. Supporting clinical data, administration of SARS-CoV-2 Spike 1 (S1) glycoprotein or receptor-binding domain (RBD) proteins into human angiotensin-converting enzyme 2 (hACE2) transgenic mice induced cardiac fibrosis and dysfunction associated with higher NF-κB phosphorylation (pNF-κB) and cardiopulmonary-derived IL-18 and NLRP3 expression. IL-18 inhibition via IL-18BP resulted in decreased cardiac pNF-κB and improved cardiac fibrosis and dysfunction in S1- or RBD-exposed hACE2 mice. Through in vivo and in vitro work, both S1 and RBD proteins induced NLRP3 inflammasome and IL-18 expression by inhibiting mitophagy and increasing mitochondrial reactive oxygenation species. Enhancing mitophagy prevented Spike protein-mediated IL-18 expression. Moreover, IL-18 inhibition reduced Spike protein-mediated pNF-κB and EC permeability. Overall, the link between reduced mitophagy and inflammasome activation represents a novel mechanism during COVID-19 pathogenesis and suggests IL-18 and mitophagy as potential therapeutic targets.

SARS-CoV-2 viral protein ORF3A injures renal tubules by interacting with TRIM59 to induce STAT3 activation

Acute kidney injury occurs frequently in COVID-19 patients infected by the coronavirus SARS-CoV-2, and infection of kidney cells by this virus has been reported. However, little is known about the direct impact of the SARS-CoV-2 infection upon the renal tubular cells. We report that SARS-CoV-2 activated signal transducer and activator of transcription 3 (STAT3) signaling and caused cellular injury in the human renal tubular cell line. Mechanistically, the viral protein ORF3A of SARS-CoV-2 augmented both NF-κB and STAT3 signaling and increased the expression of kidney injury molecule 1. SARS-CoV-2 infection or expression of ORF3A alone elevated the protein level of tripartite motif-containing protein 59 (TRIM59), an E3 ubiquitin ligase, which interacts with both ORF3A and STAT3. The excessive TRIM59 in turn dissociated the phosphatase TCPTP from binding to STAT3 and hence inhibited the dephosphorylation of STAT3, leading to persistent STAT3 activation. Consistently, ORF3A induced renal injury in zebrafish and mice. In addition, expression of TRIM59 was elevated in the kidney autopsies of COVID-19 patients with acute kidney injury. Thus, the aberrant activation of STAT3 signaling by TRIM59 plays a significant role in the renal tubular cell injury caused by SARS-CoV-2, which suggests a potential targeted therapy for the renal complications of COVID-19.

Colchicine - Renaissance of an "ancient" drug

Colchicine, which was already used by the ancient Egyptians, has recently experienced a renaissance in various medical disciplines, including dermatology. However, due to the potentially significant side effects of systemic use, many clinicians are cautious in their use of colchicine. This review provides a practical overview of the data on the established and emerging use of systemic and topical colchicine in dermatologic diseases.

The effects of lipoic acid on respiratory diseases

Respiratory diseases, including lung cancer, pulmonary fibrosis, asthma, and the recently emerging fatal coronavirus disease-19 (COVID-19), are the leading causes of illness and death worldwide. The increasing incidence and mortality rates have attracted much attention to the prevention and treatment of these conditions. Lipoic acid (LA), a naturally occurring organosulfur compound, is not only essential for mitochondrial aerobic metabolism but also shows therapeutic potential via certain pharmacological effects (e.g., antioxidative and anti-inflammatory effects). In recent years, accumulating evidence (animal experiments and in vitro studies) has suggested a role of LA in ameliorating many respiratory diseases (e.g., lung cancer, fibrosis, asthma, acute lung injury and smoking-induced lung injury). Therefore, this review will provide an overview of the present investigational evidence on the therapeutic effect of LA against respiratory diseases in vitro and in vivo. We also summarize the corresponding mechanisms of action to inspire further basic studies and clinical trials to confirm the health benefits of LA in the context of respiratory diseases.

Dantrolene and ryanodine receptors in COVID-19: The daunting task and neglected warden

Dantrolene (DTN) is a ryanodine receptor (RyR) antagonist that inhibits Ca²⁺ release from stores in the sarcoplasmic reticulum. DTN is mainly used in the management of malignant hyperthermia. RyRs are highly expressed in immune cells and are involved in different viral infections, including severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2), because Ca²⁺ is necessary for viral replication, maturation and release. DTN can inhibit the proliferation of SARS-CoV-2, indicating its potential role in reducing entry and pathogenesis of SARS-CoV-2. DTN may increase clearance of SARS-CoV-2 and promote coronavirus disease 2019 (COVID-19) recovery by shortening the period of infection. DTN inhibits N-methyl-D-aspartate (NMDA) mediated platelets aggregations and thrombosis. Therefore, DTN may inhibit thrombosis and coagulopathy in COVID-19 through suppression of platelet NMDA receptors. Moreover, DTN has a neuroprotective effect against SARS-CoV-2 infection-induced brain injury through modulation of NMDA receptors, which are involved in excitotoxicity, neuronal injury and the development of neuropsychiatric disorders. In conclusion, DTN by inhibiting RyRs may attenuate inflammatory disorders in SARS-CoV-2 infection and associated cardio-pulmonary complications. Therefore, DNT could be a promising drug therapy against COVID-19. Preclinical and clinical studies are warranted in this regards.

Exploring the Role of Immune System and Inflammatory Cytokines in SARS-CoV-2 Induced Lung Disease: A Narrative Review

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative pathogen of coronavirus disease 19 (COVID-19). COVID-19 can manifest with a heterogenous spectrum of disease severity, from mild upper airways infection to severe interstitial pneumonia and devastating acute respiratory distress syndrome (ARDS). SARS-CoV-2 infection may induce an over activation of the immune system and the release of high concentrations of pro-inflammatory cytokines, leading to a "cytokine storm", a recognized pathogenetic mechanism in the genesis of SARS-CoV-2-induced lung disease. This overproduction of inflammatory cytokines has been recognized as a poor prognostic factor, since it can lead to disease progression, organ failure, ARDS and death. Moreover, the immune system shows dysregulated activity, particularly through activated macrophages and T-helper cells and in the co-occurrent exhaustion of lymphocytes. We carried out a non-systematic literature review aimed at providing an overview of the current knowledge on the pathologic mechanisms played by the immune system and the inflammation in the genesis of SARS-CoV-2-induced lung disease. An overview on potential treatments for this harmful condition and for contrasting the "cytokine storm" has also been presented. Finally, a look at the experimented experimental vaccines against SARS-CoV-2 has been included.

Involvement of NLRP3 Inflammasome in SARS-Cov-2-Induced Multiorgan Dysfunction in Patients with COVID-19: A Review of Molecular Mechanisms

Nucleotide-binding domain and leucine-rich repeat protein- 3 (NLRP3) inflammasome is a critical component of the innate immune system. The inflammasome activation is correlated with the COVID- 19 severity. Furthermore, the underlying conditions are accompanied by hyperactivation of NLRP3 inflammasome and poor outcomes. Herein, we presented the involvement of NLRP3 inflammasome in the pathogenies of SARS-CoV-2-induced multiorgan dysfunction and potential therapeutics. Overexpression of NLRP3 inflammasome components and subsequently increased levels of cytokines following viral infection leads to the cytokine storm and indirectly affects the organ functions. Besides, invading host cells via SARS-CoV-2 further activates the NLRP3 inflammasome and induces pyroptosis in immune cells, resulting in the secretion of higher levels of proinflammatory cytokines into the extracellular matrix. These events continued by induction of fibrosis and organ dysfunction following infection with SARS-CoV-2 in critically ill patients. This condition can be observed in individuals with comorbidities (e.g., diabetes, obesity, etc.) due to a primed state of immunity, which can cause severe disease or death in this population. Therefore, understanding the mechanisms underlying host-SARS-CoV-2 interaction may help to clarify the pathophysiology of SARS-CoV-2- induced multiorgan dysfunction and introduce potential therapeutic strategies.

Multifactorial Causation of Alzheimer's Disease Due to COVID-19

There are several implications of the surge in the incidence of pandemics and epidemics in the last decades. COVID-19 being the most remarkable one, showed the vulnerability of patients with neurodegenerative diseases like Alzheimer's disease (AD). This review studies the pathological interlinks and triggering factors between the two illnesses and proposes a multifactorial pathway of AD causation due to COVID-19. The article evaluates and describes all the postulated hypotheses which explain the etiology and possible pathogenesis of the disease in four domains: Inflammation & Neurobiochemical interactions, Oxidative Stress, Genetic Factors, and Social Isolation. We believe that a probable hypothesis of an underlying cause of AD after COVID-19 infection could be the interplay of all these factors.

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.

Associations between Periodontitis, COVID-19, and Cardiometabolic Complications: Molecular Mechanisms and Clinical Evidence

Periodontitis is a microbially driven, host-mediated disease that leads to loss of periodontal attachment and resorption of bone. It is associated with the elevation of systemic inflammatory markers and with the presence of systemic comorbidities. Coronavirus disease 2019 (COVID-19) is a contagious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Although the majority of patients have mild symptoms, others experience important complications that can lead to death. After the spread of the COVID-19 pandemic, several investigations demonstrating the possible relationship between periodontitis and COVID-19 have been reported. In addition, both periodontal disease and COVID-19 seem to provoke and/or impair several cardiometabolic complications such as cardiovascular disease, type 2 diabetes, metabolic syndrome, dyslipidemia, insulin resistance, obesity, non-alcoholic fatty liver disease, and neurological and neuropsychiatric complications. Therefore, due to the increasing number of investigations focusing on the periodontitis-COVID-19 relationship and considering the severe complications that such an association might cause, this review aims to summarize all existing emerging evidence regarding the link between the periodontitis-COVID-19 axis and consequent cardiometabolic impairments.

Small molecules in the treatment of COVID-19

The outbreak of COVID-19 has become a global crisis, and brought severe disruptions to societies and economies. Until now, effective therapeutics against COVID-19 are in high demand. Along with our improved understanding of the structure, function, and pathogenic process of SARS-CoV-2, many small molecules with potential anti-COVID-19 effects have been developed. So far, several antiviral strategies were explored. Besides directly inhibition of viral proteins such as RdRp and Mpro, interference of host enzymes including ACE2 and proteases, and blocking relevant immunoregulatory pathways represented by JAK/STAT, BTK, NF-κB, and NLRP3 pathways, are regarded feasible in drug development. The development of small molecules to treat COVID-19 has been achieved by several strategies, including computer-aided lead compound design and screening, natural product discovery, drug repurposing, and combination therapy. Several small molecules representative by remdesivir and paxlovid have been proved or authorized emergency use in many countries. And many candidates have entered clinical-trial stage. Nevertheless, due to the epidemiological features and variability issues of SARS-CoV-2, it is necessary to continue exploring novel strategies against COVID-19. This review discusses the current findings in the development of small molecules for COVID-19 treatment. Moreover, their detailed mechanism of action, chemical structures, and preclinical and clinical efficacies are discussed.

The potential link between Covid-19 and multiple myeloma: A new saga

BACKGROUND

Covid-19 is considered a primary respiratory disease-causing viral pneumonia and, in severe cases, leads to acute lung injury and acute respiratory distress syndrome (ARDS). In addition, though, extra-pulmonary manifestations of Covid-19 have been shown. Furthermore, severe acute respiratory distress syndrome coronavirus type 2 (SARS-CoV-2) infection may coexist with several malignancies, including multiple myeloma (MM).

METHODS

This critical literature review aimed to find the potential association between SARS-CoV-2 infection and MM in Covid-19 patients with underlying MM. Narrative literature and databases search revealed that ARDS is developed in both MM and Covid-19 due to hypercalcemia and proteasome dysfunction.

RESULTS

Notably, the expression of angiogenic factors and glutamine deficiency could link Covid-19 severity and MM in the pathogenesis of cardiovascular complications. MM and Covid-19 share thrombosis as a typical complication; unlike thrombosis in Covid-19, which reflects disease severity, thrombosis does not reflect disease severity in MM. In both conditions, thromboprophylaxis is essential to prevent pulmonary thrombosis and other thromboembolic disorders. Moreover, Covid-19 may exacerbate the development of acute kidney injury and neurological complications in MM patients.

CONCLUSION

These findings highlighted that MM patients might be a risk group for Covid-19 severity due to underlying immunosuppression and most of those patients need specific management in the Covid-19 era.

COVID-19 and the risk of Alzheimer's disease, amyotrophic lateral sclerosis, and multiple sclerosis

BACKGROUND

The coronavirus disease 2019 (COVID-19) pandemic has had an unprecedented impact on the healthcare system, economy, and society. Studies have reported that COVID-19 may cause various neurologic symptoms, including cognitive impairment. We aimed to assess the causal effect of COVID-19 on neurodegenerative diseases using two-sample Mendelian randomization (MR) study.

METHODS

Genetic variants were obtained from genome-wide association studies (GWAS) summary-level data and meta-analyses. We used the inverse variance-weighted (IVW) method as the primary analysis to estimate causal effects. Sensitivity analyses were performed to make the conclusions more robust and reliable.

RESULTS

We found that the COVID-19 infection phenotype was associated with a higher risk of AD and inverse associated with the risk of ALS and MS. The hospitalized COVID-19 phenotype was associated with the risk of AD and wasn't associated with ALS and MS. We also found that the severe COVID-19 (main analysis) phenotype was associated with the AD outcome from UK biobank datasets but was not associated with other outcomes. The severe COVID-19 infection phenotype, the severe COVID-19 (subtype analysis) phenotype and the hospitalization risk of COVID-19 were not associated with each outcome.

CONCLUSION

This MR study suggests a potential association between genetically predicted COVID-19 and a higher risk of AD and a reduced risk of ALS and MS. Further elucidations of this association and underlying mechanisms may inform public health messages to prevent COVID-19 and AD.

Infection and chronic disease activate a brain-muscle signaling axis that regulates muscle performance

Infections and neurodegenerative diseases induce neuroinflammation, but affected individuals often show a number of non-neural symptoms including muscle pain and muscle fatigue. The molecular pathways by which neuroinflammation causes pathologies outside the central nervous system (CNS) are poorly understood, so we developed three models to investigate the impact of neuroinflammation on muscle performance. We found that bacterial infection, COVID-like viral infection, and expression of a neurotoxic protein associated with Alzheimer' s disease promoted the accumulation of reactive oxygen species (ROS) in the brain. Excessive ROS induces the expression of the cytokine Unpaired 3 (Upd3) in insects, or its orthologue IL-6 in mammals, and CNS-derived Upd3/IL-6 activates the JAK/Stat pathway in skeletal muscle. In response to JAK/Stat signaling, mitochondrial function is impaired and muscle performance is reduced. Our work uncovers a brain-muscle signaling axis in which infections and chronic diseases induce cytokine-dependent changes in muscle performance, suggesting IL-6 could be a therapeutic target to treat muscle weakness caused by neuroinflammation.

Circular RNAs as emerging regulators in COVID-19 pathogenesis and progression

Coronavirus disease 2019 (COVID-19), an infectious acute respiratory disease caused by a newly emerging RNA virus, is a still-growing pandemic that has caused more than 6 million deaths globally and has seriously threatened the lives and health of people across the world. Currently, several drugs have been used in the clinical treatment of COVID-19, such as small molecules, neutralizing antibodies, and monoclonal antibodies. In addition, several vaccines have been used to prevent the spread of the pandemic, such as adenovirus vector vaccines, inactivated vaccines, recombinant subunit vaccines, and nucleic acid vaccines. However, the efficacy of vaccines and the onset of adverse reactions vary among individuals. Accumulating evidence has demonstrated that circular RNAs (circRNAs) are crucial regulators of viral infections and antiviral immune responses and are heavily involved in COVID-19 pathologies. During novel coronavirus infection, circRNAs not only directly affect the transcription process and interfere with viral replication but also indirectly regulate biological processes, including virus-host receptor binding and the immune response. Consequently, understanding the expression and function of circRNAs during severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection will provide novel insights into the development of circRNA-based methods. In this review, we summarize recent progress on the roles and underlying mechanisms of circRNAs that regulate the inflammatory response, viral replication, immune evasion, and cytokines induced by SARS-CoV-2 infection, and thus highlighting the diagnostic and therapeutic challenges in the treatment of COVID-19 and future research directions.

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.

Genetic variants determine intrafamilial variability of SARS-CoV-2 clinical outcomes in 19 Italian families

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection results in a wide range of outcomes characterized by a high heterogeneity in both symptomatology and susceptibility to the disease. In such a perspective, COVID-19 may be considered as a multifactorial disease featured by the interaction between the environment, which is the virus itself, and the genetic profile of the host. Our analysis aimed at investigating the transmission dynamics of SARS-CoV-2 within families whose members responded in different ways to the infection, although the exposure was common to the entire group and occurred before the availability of any vaccine. The goal was to understand how the genetic background of each subject can influence the viral infection outcome and hence the above-mentioned clinical variability. We performed a segregation analysis in 19 Italian families with a designed custom panel of 42 genes involved in immunity and virus entry and which have also been shown to be related to SARS-CoV-2 host response. We carried out both a familial segregation analysis and a global statistical analysis. In the former we identified eighteen risk variants co-segregating with a COVID-positive status and six variants with a possible protective effect. In addition, sixteen variants showed a trend of association to a severe phenotype. Together with common SNPs, we detected private rare variants that may also provide insight into the observed clinical COVID-19 heterogeneity. The global statistical analysis confirmed statistically significant positive associations between SARS-CoV-2 individual response and some specific gene variants identified in familial analysis. In conclusion our data confirm that the clinical expression of COVID-19 is markedly influenced by the host genetic profile both with a mendelian transmission pattern and a polygenic architecture.

Ursolic acid and SARS-CoV-2 infection: a new horizon and perspective

SARS-CoV-2 (severe acute respiratory syndrome coronavirus type 2) has been identified as the source of a world coronavirus pandemic in 2019. Covid-19 is considered a main respiratory disease-causing viral pneumonia and, in severe cases, leads to acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). Although, extrapulmonary manifestations of Covid-19 like neurological, cardiovascular, and gastrointestinal have been confirmed. Exaggerated immune response and release of a high amount of pro-inflammatory cytokines may progress, causing a cytokine storm. Consequently, direct and indirect effects of SARS-CoV-2 infection can evolve into systemic complications due to the progression of hyper inflammation, oxidative stress and dysregulation of the renin-angiotensin system (RAS). Therefore, anti-inflammatory and antioxidant agents could be efficient in alleviating these disorders. Ursolic acid has anti-inflammatory, antioxidant, and antiviral effects; it reduces the release of pro-inflammatory cytokines, improves anti-inflammatory cytokines, and inhibits the production of reactive oxygen species (ROS). In virtue of its anti-inflammatory and antioxidant effects, ursolic acid may minimize SARS-CoV-2 infection-induced complications. Also, by regulating RAS and inflammatory signaling pathways, ursolic acid might effectively reduce the development of ALI in ARDS in Covid-19. In this state, this perspective discusses how ursolic acid can mitigate hyper inflammation and oxidative stress in 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.

Are Nutraceuticals Effective in COVID-19 and Post-COVID Prevention and Treatment?

The beginning of the end or the end of the beginning? After two years mastered by coronavirus disease 19 (COVID-19) pandemic, we are now witnessing a turnaround. The reduction of severe cases and deaths from COVID-19 led to increasing importance of a new disease called post-COVID syndrome. The term post-COVID is used to indicate permanency of symptoms in patients who have recovered from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Immune, antiviral, antimicrobial therapies, as well as ozone therapy have been used to treat COVID-19 disease. Vaccines have then become available and administered worldwide to prevent the insurgence of the disease. However, the pandemic is not over yet at all given the emergence of new omicron variants. New therapeutic strategies are urgently needed. In this view, great interest was found in nutraceutical products, including vitamins (C, D, and E), minerals (zinc), melatonin, probiotics, flavonoids (quercetin), and curcumin. This review summarizes the role of nutraceuticals in the prevention and/or treatment of COVID-19 disease and post-COVID syndrome.

Developing dendritic cell for SARS-CoV-2 vaccine: Breakthrough in the pandemic

Finding a vaccine that can last a long time and effective against viruses with high mutation rates such as SARS-CoV-2 is still a challenge today. The various vaccines that have been available have decreased in effectiveness and require booster administration. As the professional antigen presenting cell, Dendritic Cells can also activate the immune system, especially T cells. This ability makes dendritic cells have been developed as vaccines for some types of diseases. In SARS-CoV-2 infection, T cells play a vital role in eliminating the virus, and their presence can be detected in the long term. Hence, this condition shows that the formation of T cell immunity is essential to prevent and control the course of the disease. The construction of vaccines oriented to induce strong T cells response can be formed by utilizing dendritic cells. In this article, we discuss and illustrate the role of dendritic cells and T cells in the pathogenesis of SARS-CoV-2 infection and summarizing the crucial role of dendritic cells in the formation of T cell immunity. We arrange the basis concept of developing dendritic cells for SARS-CoV-2 vaccines. A dendritic cell-based vaccine for SARS-CoV-2 has the potential to be an effective vaccine that solves existing problems.

Inflammasome Genetic Variants Are Associated with Protection to Clinical Severity of COVID-19 among Patients from Rio de Janeiro, Brazil

COVID-19 has a broad spectrum of clinical manifestations, from asymptomatic or mild/moderate symptoms to severe symptoms and death. The mechanisms underlying its clinical evolution are still unclear. Upon SARS-CoV-2 infection, host factors, such as the inflammasome system, are activated by the presence of the virus inside host cells. The search for COVID-19 risk factors is of relevance for clinical management. In this study, we investigated the impact of inflammasome single-nucleotide polymorphisms (SNPs) in SARS-CoV-2-infected individuals with distinct severity profiles at clinical presentation. Patients were divided into two groups according to disease severity at clinical presentation based on the WHO Clinical Progression Scale. Group 1 included patients with mild/moderate disease (WHO < 6; n = 76), and group 2 included patients with severe/critical COVID-19 (WHO ≥ 6; n = 357). Inpatients with moderate to severe/critical profiles were recruited and followed-up at Hospital Center for COVID-19 Pandemic – National Institute of Infectology (INI)/FIOCRUZ, RJ, Brazil, from June 2020 to March 2021. Patients with mild disease were recruited at Oswaldo Cruz Institute (IOC)/FIOCRUZ, RJ, Brazil, in August 2020. Genotyping of 11 inflammasome SNPs was determined by real-time PCR. Protection and risk estimation were performed using unconditional logistic regression models. Significant differences in NLRP3 rs1539019 and CARD8 rs2043211 were observed between the two groups. Protection against disease severity was associated with the A/A genotype (OR_adj = 0.36; P = 0.032), allele A (OR_adj = 0.93; P = 0.010), or carrier-A (OR_adj = 0.45; P = 0.027) in the NLRP3 rs1539019 polymorphism; A/T genotype (OR_adj = 0.5; P = 0.045), allele T (OR_adj = 0.93; P = 0.018), or carrier-T (OR_adj = 0.48; P = 0.029) in the CARD8 rs2043211 polymorphism; and the A-C-G-C-C (OR_adj = 0.11; P = 0.018), A-C-G-C-G (OR_adj = 0.23; P = 0.003), C-C-G-C-C (OR_adj = 0.37; P = 0.021), and C-T-G-A-C (OR_adj = 0.04; P = 0.0473) in NLRP3 genetic haplotype variants. No significant associations were observed for the other polymorphisms. To the best of our knowledge, this is the first study demonstrating an association between CARD8 and NLRP3 inflammasome genetic variants and protection against COVID-19 severity, contributing to the discussion of the impact of inflammasomes on COVID-19 outcomes.

Inflammatory pathways in COVID-19: Mechanism and therapeutic interventions

The 2019 coronavirus disease (COVID-19) pandemic has become a global crisis. In the immunopathogenesis of COVID-19, SARS-CoV-2 infection induces an excessive inflammatory response in patients, causing an inflammatory cytokine storm in severe cases. Cytokine storm leads to acute respiratory distress syndrome, pulmonary and other multiorgan failure, which is an important cause of COVID-19 progression and even death. Among them, activation of inflammatory pathways is a major factor in generating cytokine storms and causing dysregulated immune responses, which is closely related to the severity of viral infection. Therefore, elucidation of the inflammatory signaling pathway of SARS-CoV-2 is important in providing otential therapeutic targets and treatment strategies against COVID-19. Here, we discuss the major inflammatory pathways in the pathogenesis of COVID-19, including induction, function, and downstream signaling, as well as existing and potential interventions targeting these cytokines or related signaling pathways. We believe that a comprehensive understanding of the regulatory pathways of COVID-19 immune dysregulation and inflammation will help develop better clinical therapy strategies to effectively control inflammatory diseases, such as COVID-19.

Symptomatology and microbiology of the gastrointestinal tract in post-COVID conditions

Post-COVID conditions, also known as post-acute sequelae of SARS-CoV-2 (PASC), refer to the persistence of symptoms in COVID-19 long-haulers. Various manifestations of post-COVID conditions are general symptoms and/or manifestations of damage in multiple organs. Besides, SARS-CoV-2 can involve the gastrointestinal tract, resulting in sequelae such as diarrhea, abdominal pain, nausea, anorexia, vomiting, constipation, abdominal distension, acid reflux, and/or gastrointestinal bleeding. Previous investigations point to SARS-CoV-2 entry into enterocytes enhances by the angiotensin-converting enzyme 2 (ACE2) receptors. Interestingly, ACE2 receptors are abundantly expressed in the gut, implying infection with SARS-CoV-2 might occur through this route as well as in the respiratory tract. According to mounting evidence, SARS-CoV-2 RNA has been identified in fecal specimens of patients with COVID-19 during and beyond the acute phase. In addition, studies have shown gut microbiome composition is altered in patients with PASC, hence, another putative mechanism linked to gastrointestinal symptoms is gut dysbiosis. The presence of the gut-lung axis in COVID-19 might have major implications for disease pathogenesis and treatment. This review discussed the prevalence of gastrointestinal symptoms and pathophysiology underlying possible infection of the gut in patients with PASC. Also, SARS-COV-2 induced NLRP3 inflammasome-dependent inflammatory pathways are briefly addressed.