Cytokine Storm Syndrome in SARS-CoV-2 Infections: A Functional Role of Mast Cells

The critical impacts of cytokine storms in respiratory disorders

Cytokine storm (CS) refers to the spontaneous dysregulated and hyper-activated inflammatory reaction occurring in various clinical conditions, ranging from microbial infection to end-stage organ failure. Recently the novel coronavirus involved in COVID-19 (Coronavirus disease-19) caused by SARS-CoV-2 (Severe Acute Respiratory Syndrome Coronavirus 2) has been associated with the pathological phenomenon of CS in critically ill patients. Furthermore, critically ill patients suffering from CS are likely to have a grave prognosis and a higher case fatality rate. Pathologically CS is manifested as hyper-immune activation and is clinically manifested as multiple organ failure. An in-depth understanding of the etiology of CS will enable the discovery of not just disease risk factors of CS but also therapeutic approaches to modulate the immune response and improve outcomes in patients with respiratory diseases having CS in the pathogenic pathway. Owing to the grave consequences of CS in various diseases, this phenomenon has attracted the attention of researchers and clinicians throughout the globe. So in the present manuscript, we have attempted to discuss CS and its ramifications in COVID-19 and other respiratory diseases, as well as prospective treatment approaches and biomarkers of the cytokine storm. Furthermore, we have attempted to provide in-depth insight into CS from both a prophylactic and therapeutic point of view. In addition, we have included recent findings of CS in respiratory diseases reported from different parts of the world, which are based on expert opinion, clinical case-control research, experimental research, and a case-controlled cohort approach.

Highlight of 2023: Advances in mast cells

In this article for the Highlights of 2023 Series, we consider the growing understanding of mast cell heterogeneity and interactions that has developed from single cell RNA sequencing studies. We also discuss novel concepts concerning mast cell interactions with the central nervous system and evidence for their role in host defense against SARS-CoV-2 infection.

Unraveling antiviral efficacy of multifunctional immunomodulatory triterpenoids against SARS-COV-2 targeting main protease and papain-like protease

The coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) may be over, but its variants continue to emerge, and patients with mild symptoms having long COVID is still under investigation. SARS-CoV-2 infection leading to elevated cytokine levels and suppressed immune responses set off cytokine storm, fatal systemic inflammation, tissue damage, and multi-organ failure. Thus, drug molecules targeting the SARS-CoV-2 virus-specific proteins or capable of suppressing the host inflammatory responses to viral infection would provide an effective antiviral therapy against emerging variants of concern. Evolutionarily conserved papain-like protease (PLpro) and main protease (Mpro) play an indispensable role in the virus life cycle and immune evasion. Direct-acting antivirals targeting both these viral proteases represent an attractive antiviral strategy that is also expected to reduce viral inflammation. The present study has evaluated the antiviral and anti-inflammatory potential of natural triterpenoids: azadirachtin, withanolide_A, and isoginkgetin. These molecules inhibit the Mpro and PLpro proteolytic activities with half-maximal inhibitory concentrations (IC50) values ranging from 1.42 to 32.7 μM. Isothermal titration calorimetry (ITC) analysis validated the binding of these compounds to Mpro and PLpro. As expected, the two compounds, withanolide_A and azadirachtin, exhibit potent anti-SARS-CoV-2 activity in cell-based assays, with half-maximum effective concentration (EC50) values of 21.73 and 31.19 μM, respectively. The anti-inflammatory roles of azadirachtin and withanolide_A when assessed using HEK293T cells, were found to significantly reduce the levels of CXCL10, TNFα, IL6, and IL8 cytokines, which are elevated in severe cases of COVID-19. Interestingly, azadirachtin and withanolide_A were also found to rescue the decreased type-I interferon response (IFN-α1). The results of this study clearly highlight the role of triterpenoids as effective antiviral molecules that target SARS-CoV-2-specific enzymes and also host immune pathways involved in virus-mediated inflammation.

Modulating effect of Eunkyo-san on expression of inflammatory cytokines and angiotensin-converting enzyme 2 in human mast cells

Eunkyo-san is widely used in the treatment of severe respiratory infections. Mast cells not only serve as host cells for the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), but also they also exacerbate Coronavirus disease in 2019 (COVID-19) by causing a cytokine storm. Here we investigated whether Eunkyo-san and its active compound naringenin regulate the expression of inflammatory cytokines and factors connected to viral infection in activated human mast cell line, HMC-1 cells. Eunkyo-san and naringenin significantly reduced levels of inflammatory cytokines including interleukin (IL)-1β, IL-6, IL-8, thymic stromal lymphopoietin, and tumor necrosis factor-α without impacting cytotoxicity. Eunkyo-san and naringenin reduced levels of factors connected to SARS-CoV-2 infection such as angiotensin-converting enzyme 2 (ACE2, SARS-CoV-2 receptor), transmembrane protease/serine subfamily member 2, and tryptase in activated HMC-1 cells. Treatment with Eunkyo-san and naringenin considerably reduced expression levels of ACE2 transcription factor, AP-1 (C-JUN and C-FOS) by blocking phosphatidylinositide-3-kinase and c-Jun NH2-terminal kinases signaling pathways. In addition, Eunkyo-san and naringenin effectively suppressed activation of signal transducer and activator of transcription 3, nuclear translocation of nuclear factor-κB, and activation of caspase-1 in activated HMC-1 cells. Furthermore, Eunkyo-san and naringenin reduced expression of ACE2 mRNA in two activated mast cell lines, RBL-2H3 and IC-2 cells. The overall study findings showed that Eunkyo-san diminished the expression levels of inflammatory cytokines and ACE2, and these findings imply that Eunkyo-san is able to effectively mitigating the cytokine storm brought on by SARS-CoV-2 infection.

SARS-CoV-2 ORF8 as a Modulator of Cytokine Induction: Evidence and Search for Molecular Mechanisms

Severe cases of SARS-CoV-2 infection are characterized by an immune response that leads to the overproduction of pro-inflammatory cytokines, resulting in lung damage, cardiovascular symptoms, hematologic symptoms, acute kidney injury and multiple organ failure that can lead to death. This remarkable increase in cytokines and other inflammatory molecules is primarily caused by viral proteins, and particular interest has been given to ORF8, a unique accessory protein specific to SARS-CoV-2. Despite plenty of research, the precise mechanisms by which ORF8 induces proinflammatory cytokines are not clear. Our investigations demonstrated that ORF8 augments production of IL-6 induced by Poly(I:C) in human embryonic kidney (HEK)-293 and monocyte-derived dendritic cells (mono-DCs). We discuss our findings and the multifaceted roles of ORF8 as a modulator of cytokine response, focusing on type I interferon and IL-6, a key component of the immune response to SARS-CoV-2. In addition, we explore the hypothesis that ORF8 may act through pattern recognition receptors of dsRNA such as TLRs.

Radiological features of COVID-19-associated mucormycosis: A report of 36 cases along with a literature review

The pandemic of COVID-19 along with high use of corticosteroids resulted in the emergence of invasive fungal infection. Here, we reported the radiologic feature of mucormycosis in COVID-19-infected cases and reviewed with available literature.

Two synthetic steroid analogs reduce human respiratory syncytial virus replication and the immune response to infection both in vitro and in vivo

HRSV is responsible for many acute lower airway infections and hospitalizations in infants, the elderly and those with weakened immune systems around the world. The strong inflammatory response that mediates viral clearance contributes to pathogenesis, and is positively correlated with disease severity. There is no specific effective therapy on hand. Antiviral synthetic stigmastanes (22S, 23S)-22,23-dihydroxystigmast-4-en-3-one (Compound 1) and 22,23-dihydroxystigmasta-1,4-dien-3-one (Compound 2) have shown to be active inhibiting unrelated virus like Herpes Simplex type 1 virus (HSV-1) and Adenovirus, without cytotoxicity. We have also shown that Compound 1 modulates the activation of cell signaling pathways and cytokine secretion in infected epithelial cells as well as in inflammatory cells activated by nonviral stimuli. In the present work, we investigated the inhibitory effect of both compounds on HRSV replication and their modulatory effect on infected epithelial and inflammatory cells. We show that compounds 1 and 2 inhibit in vitro HRSV replication and propagation and reduce cytokine secretion triggered by HRSV infection in epithelial and inflammatory cells. The compounds reduce viral loads and inflammatory infiltration in the lungs of mice infected with HRSV.

The Impact of Co-Infections for Human Gammaherpesvirus Infection and Associated Pathologies

The two oncogenic human gammaherpesviruses Epstein-Barr virus (EBV) and Kaposi's sarcoma-associated herpesvirus (KSHV) cause significant disease burden, particularly in immunosuppressed individuals. Both viruses display latent and lytic phases of their life cycle with different outcomes for their associated pathologies. The high prevalence of infectious diseases in Sub-Saharan Africa (SSA), particularly HIV/AIDS, tuberculosis, malaria, and more recently, COVID-19, as well as their associated inflammatory responses, could potentially impact either virus' infectious course. However, acute or lytically active EBV and/or KSHV infections often present with symptoms mimicking these predominant diseases leading to misdiagnosis or underdiagnosis of oncogenic herpesvirus-associated pathologies. EBV and/or KSHV infections are generally acquired early in life and remain latent until lytic reactivation is triggered by various stimuli. This review summarizes known associations between infectious agents prevalent in SSA and underlying EBV and/or KSHV infection. While presenting an overview of both viruses' biphasic life cycles, this review aims to highlight the importance of co-infections in the correct identification of risk factors for and diagnoses of EBV- and/or KSHV-associated pathologies, particularly in SSA, where both oncogenic herpesviruses as well as other infectious agents are highly pervasive and can lead to substantial morbidity and mortality.

Identification of biomarkers associated with diagnosis of acute lung injury based on bioinformatics and machine learning

BACKGROUND

Acute lung injury (ALI) is an acute inflammatory disease characterized by excess production of inflammatory factors in lung tissue and has a high mortality. This research was designed for the identification of novel diagnostic biomarkers for ALI and analyzing the possible association between critical genes and infiltrated immune cells.

METHODS

The study used 2 datasets (GSE2411 and GSE18341) to identify differentially expressed genes (DEGs) between 2 groups. Then we performed Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses to identify the functions of these DEGs. The study also used SVM-recursive feature elimination analysis and least absolute shrinkage and selection operator regression model to screen possible markers. The study further analyzed immune cell infiltration via CIBERSORT. Gene Set Enrichment Analysis was used to explore the molecular mechanism of the critical genes.

RESULTS

DEGs were identified between 2 groups. In total, 690 DEGs were obtained: 527 genes were upregulated and 163 genes were downregulated. We identified PDZK1IP1, CCKAR, and CXCL2 as critical genes. And we then found that these critical genes correlated with Mast Cells, Neutrophil Cells, M1 Macrophage, dendritic cell Actived, Eosinophil Cells, B Cells Naive, Mast Cells, and dendritic cell Immature. Furthermore, we investigated the specific signaling pathways involved in key genes and derived some potential molecular mechanisms by which key genes affect disease progression by use of Gene Set Enrichment Analysis. Moreover, we predict transcription factors. Also, we obtained critical gene-related microRNAs through the targetscan database, and visualized the microRNA network of the genes.

CONCLUSION

Our findings might provide some novel clue for the exploration of novel markers for ALI diagnosis. The critical genes and their associations with immune infiltration may offer new insight into understanding ALI developments.

Impact of age and sex on neuroinflammation following SARS-CoV-2 infection in a murine model

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), the etiological agent for the worldwide COVID-19 pandemic, is known to infect people of all ages and both sexes. Senior populations have the greatest risk of severe disease, and sexual dimorphism in clinical outcomes has been reported in COVID-19. SARS-CoV-2 infection in humans can cause damage to multiple organ systems, including the brain. Neurological symptoms are widely observed in patients with COVID-19, with many survivors suffering from persistent neurological and cognitive impairment, potentially accelerating Alzheimer's disease. The present study aims to investigate the impact of age and sex on the neuroinflammatory response to SARS-CoV-2 infection using a mouse model. Wild-type C57BL/6 mice were inoculated, by intranasal route, with SARS-CoV-2 lineage B.1.351 variant known to infect mice. Older animals and in particular males exhibited a significantly greater weight loss starting at 4 dpi. In addition, male animals exhibited higher viral RNA loads and higher titers of infectious virus in the lung, which was particularly evident in males at 16 months of age. Notably, no viral RNA was detected in the brains of infected mice, regardless of age or sex. Nevertheless, expression of IL-6, TNF-α, and CCL-2 in the lung and brain was increased with viral infection. An unbiased brain RNA-seq/transcriptomic analysis showed that SARS-CoV-2 infection caused significant changes in gene expression profiles in the brain, with innate immunity, defense response to virus, cerebravascular and neuronal functions, as the major molecular networks affected. The data presented in this study show that SARS-CoV-2 infection triggers a neuroinflammatory response despite the lack of detectable virus in the brain. Age and sex have a modifying effect on this pathogenic process. Aberrant activation of innate immune response, disruption of blood-brain barrier and endothelial cell integrity, and supression of neuronal activity and axonogenesis underlie the impact of SARS-CoV-2 infection on the brain. Understanding the role of these affected pathways in SARS-CoV-2 pathogenesis helps identify appropriate points of therapeutic interventions to alleviate neurological dysfunction observed during COVID-19.

Interleukin 18 and IL-18 BP response to Sars-CoV-2 virus infection

The immune response to the SARS-CoV-2 infection is crucial to the patient outcome. IL-18 is involved in the lymphocyte response to the disease and it is well established its important role in the complex developing of the host response to viral infection. This study aims at the analysis of the concentrations of IL-18, IL-18BP, INF-γ at the onset of the SARS-CoV-2 infection. The serum levels of measured interleukins were obtained through enzyme-linked immunosorbent assay. Furthermore, the free fraction of IL-18 was numerically evaluated. The enrolled patients were divided in two severity groups according to a threshold value of 300 for the ratio of arterial partial pressure of oxygen and fraction of inspired oxygen fraction and according to the parenchymal involvement as evaluated by computerized tomography at the admittance. In the group of patients with a more severe disease, a significant increase of the IL-18, INF-γ and IL-18BP levels have been observed, whereas the free IL-18 component values were almost constant. The results confirm that, at the onset of the disease, the host response keep the inflammatory cytokines in an equilibrium and support the hypothesis to adopt the IL-18BP modulation as a possible and effective therapeutic approach.

Antihistamines improve cardiovascular manifestations and other symptoms of long-COVID attributed to mast cell activation

Introduction

Long-COVID is a broadly defined condition and there are no effective therapies. Cardiovascular manifestations of long-COVID include high heart rate, postural tachycardia, and palpitations. Previous studies have suggested that mast cell activation (MCA) may play a role in the pathophysiology of long-COVID, including in the mechanisms of its cardiovascular manifestations. The present study aimed to evaluate the effectiveness of a treatment with blockers of histamine receptors in patients with long-COVID who did not respond to other therapies.

Methods

In all, 14 patients (F/M = 9/5; 49.5 ± 11.5 years) and 13 controls (F/M = 8/5; 47.3 ± 8.0 years) with long-COVID symptoms attributed to MCA were evaluated. Patients were treated with fexofenadine (180 mg/day) and famotidine (40 mg/day). Fatigue, brain fog, abdominal disorders, and increased heart rate were evaluated in treated and untreated patients at baseline and 20 days later.

Results

Long-COVID symptoms disappeared completely in 29% of treated patients. There was a significant improvement in each of the considered symptoms (improved or disappeared) in all treated patients, and the improvement grade was significantly greater in treated patients compared to controls. No significant differences in the outcomes were observed in the controls.

Conclusions

Our data confirm that histamine receptors blockade may be an effective target to successfully treat long-COVID. Our finding supports the underlying role of MCA in the pathophysiology of long-COVID.

Activation of the NLRP1 Inflammasome and Its Role in Transmissible Gastroenteritis Coronavirus Infection

The inflammasome pathway is a critical early response mechanism of the host that detects pathogens, initiates the production of inflammatory cytokines, and recruits effector cells to the infection site. Nonetheless, the mechanism of inflammasome activation in coronavirus infection and its biological functions in host defense remain unclear. Transmissible gastroenteritis virus (TGEV), a member of the genus Alphacoronavirus, is a significant pathogen that mainly infects piglets and causes intestinal inflammation and inflammatory cell infiltration. Here, we investigated the mechanism of inflammasome activation in intestinal epithelial cells (IECs) infected with TGEV. We observed a substantial increase in interleukin 1β (IL-1β) and IL-18 levels in both IECs and TGEV-infected porcine intestinal tissues. Furthermore, TGEV infection resulted in increased activation of caspase-1 and the NLRP1 (NOD-like receptor [NLR]-containing pyrin domain [PYD]) inflammasome. Our findings revealed that TGEV infection impeded the interaction between porcine NLRP1 (pNLRP1) and porcine dipeptidyl peptidases 9 (pDPP9), yet it did not reduce the expression of pDPP9. Importantly, the ZU5 domain, not the function-to-find domain (FIIND) reported in human NLRP1, was identified as the minimal domain of pNLRP1 for pDPP9 binding. In addition, the robust type I IFN expression induced by TGEV infection also upregulated pNLRP1 expression and pNLRP1 itself acts as an interferon-stimulated gene to counteract TGEV infection. Our data demonstrate that pNLRP1 has antiviral capabilities against coronavirus infection, which highlights its potential as a novel therapeutic target for coronavirus antiviral therapy. IMPORTANCE Coronavirus primarily targets the epithelial cells of the respiratory and gastrointestinal tracts, leading to damage in both humans and animals. NLRP1 is a direct sensor for RNA virus infection which is highly expressed in epithelial barrier tissues. However, until recently, the precise molecular mechanisms underlying its activation in coronavirus infection and subsequent downstream events remained unclear. In this study, we demonstrate that the alphacoronavirus TGEV induces the production of IL-1β and IL-18 and upregulates the expression of pNLRP1. Furthermore, we found that pNLRP1 can serve as an interferon-stimulated gene (ISG) to inhibit the infection of enterovirus TGEV. Our research highlights the crucial role of NLRP1 as a regulator of innate immunity in TGEV infection and shows that it may serve as a potential therapeutic target for the treatment of coronavirus infection.

Recombinant SARS-CoV-2 Spike Protein Stimulates Secretion of Chymase, Tryptase, and IL-1β from Human Mast Cells, Augmented by IL-33

SARS-CoV-2 infects cells via its spike (S) protein binding to its surface receptor angiotensin-converting enzyme 2 (ACE2) and results in the production of multiple proinflammatory cytokines, especially in the lungs, leading to what is known as COVID-19. However, the cell source and the mechanism of secretion of such cytokines have not been adequately characterized. In this study, we used human cultured mast cells that are plentiful in the lungs and showed that recombinant SARS-CoV-2 full-length S protein (1-10 ng/mL), but not its receptor-binding domain (RBD), stimulates the secretion of the proinflammatory cytokine interleukin-1β (IL-1β) as well as the proteolytic enzymes chymase and tryptase. The secretion of IL-1β, chymase, and tryptase is augmented by the co-administration of interleukin-33 (IL-33) (30 ng/mL). This effect is mediated via toll-like receptor 4 (TLR4) for IL-1β and via ACE2 for chymase and tryptase. These results provide evidence that the SARS-CoV-2 S protein contributes to inflammation by stimulating mast cells through different receptors and could lead to new targeted treatment approaches.

Carvacrol-A Natural Phenolic Compound with Antimicrobial Properties

The main purpose of this article is to present the latest research related to selected biological properties of carvacrol, such as antimicrobial, anti-inflammatory, and antioxidant activity. As a monoterpenoid phenol, carvacrol is a component of many essential oils and is usually found in plants together with its isomer, thymol. Carvacrol, either alone or in combination with other compounds, has a strong antimicrobial effect on many different strains of bacteria and fungi that are dangerous to humans or can cause significant losses in the economy. Carvacrol also exerts strong anti-inflammatory properties by preventing the peroxidation of polyunsaturated fatty acids by inducing SOD, GPx, GR, and CAT, as well as reducing the level of pro-inflammatory cytokines in the body. It also affects the body's immune response generated by LPS. Carvacrol is considered a safe compound despite the limited amount of data on its metabolism in humans. This review also discusses the biotransformations of carvacrol, because the knowledge of the possible degradation pathways of this compound may help to minimize the risk of environmental contamination with phenolic compounds.

Mechanisms of COVID-19 Associated Pulmonary Thrombosis: A Narrative Review

COVID-19, the infectious disease caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), is frequently associated with pulmonary thrombotic events, especially in hospitalized patients. Severe SARS-CoV-2 infection is characterized by a proinflammatory state and an associated disbalance in hemostasis. Immune pathology analysis supports the inflammatory nature of pulmonary arterial thrombi composed of white blood cells, especially neutrophils, CD3+ and CD20+ lymphocytes, fibrin, red blood cells, and platelets. Immune cells, cytokines, chemokines, and the complement system are key drivers of immunothrombosis, as they induce the damage of endothelial cells and initiate proinflammatory and procoagulant positive feedback loops. Neutrophil extracellular traps induced by COVID-19-associated “cytokine storm”, platelets, red blood cells, and coagulation pathways close the inflammation–endotheliopathy–thrombosis axis, contributing to SARS-CoV-2-associated pulmonary thrombotic events. The hypothesis of immunothrombosis is also supported by the minor role of venous thromboembolism with chest CT imaging data showing peripheral blood clots associated with inflammatory lesions and the high incidence of thrombotic events despite routine thromboprophylaxis. Understanding the complex mechanisms behind COVID-19-induced pulmonary thrombosis will lead to future combination therapies for hospitalized patients with severe disease that would target the crossroads of inflammatory and coagulation pathways.

Role of SARS-CoV-2 Spike-Protein-Induced Activation of Microglia and Mast Cells in the Pathogenesis of Neuro-COVID

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes coronavirus disease 2019 (COVID-19). About 45% of COVID-19 patients experience several symptoms a few months after the initial infection and develop post-acute sequelae of SARS-CoV-2 (PASC), referred to as "Long-COVID," characterized by persistent physical and mental fatigue. However, the exact pathogenetic mechanisms affecting the brain are still not well-understood. There is increasing evidence of neurovascular inflammation in the brain. However, the precise role of the neuroinflammatory response that contributes to the disease severity of COVID-19 and long COVID pathogenesis is not clearly understood. Here, we review the reports that the SARS-CoV-2 spike protein can cause blood-brain barrier (BBB) dysfunction and damage neurons either directly, or via activation of brain mast cells and microglia and the release of various neuroinflammatory molecules. Moreover, we provide recent evidence that the novel flavanol eriodictyol is particularly suited for development as an effective treatment alone or together with oleuropein and sulforaphane (ViralProtek®), all of which have potent anti-viral and anti-inflammatory actions.

Heat stress increases immune cell function in Hexacorallia

Climate change induced heat stress has increased coral bleaching events worldwide. Differentially regulated immune genes are one of the primary responses to heat stress suggesting that immune activation is critical. However, the cellular immune mechanisms of coral bleaching is currently unknown, and it is still not known if the immune response documented during heat stress is a consequence of bleaching or is directly caused by the heat stress itself. To address this question, we have used two model system sea anemones (Order: Actiniaria): Exaiptasia diaphana and Nematostella vectensis. E. diaphana is an established sea anemone model for algal symbiont interaction, while N. vectensis is an established sea anemone model that lacks the algal symbiont. Here, we examined the effect of increased temperature on phagocytic activity, as an indication of immune function. Our data shows that immune cell activity increases during heat stress, while small molecule pinocytosis remains unaffected. We observed an increase in cellular production of reactive oxygen species with increasing temperatures. We also found that the cellular immune activity was not affected by the presence of the Symbiodiniaceae. Our results suggest that the immune activity observed in heat-stress induced bleaching in corals is a fundamental and basic response independent of the bleaching effect. These results establish a foundation for improving our understanding of hexacorallian immune cell biology, and its potential role in coral bleaching.

Mast Cell's Role in Cytokine Release Syndrome and Related Manifestations of COVID-19 Disease

In this narrative review, firstly, we describe the characteristics of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the pathogenesis of its infection in humans. Later, the importance of mast cells in SARS-CoV-2 infection and their role in Coronavirus Disease 2019 (COVID-19) will be discussed. SARS-CoV-2 is a transmissible agent frequently detected in some mammalian species and also in humans. Literature data published in PubMed that covered mast cells' role in cytokine release syndrome and related manifestations of COVID-19 disease were reviewed by the authors independently and collectively. Recommendations for the management of cytokine release syndrome and related manifestations were made by the authors. Mast cells are concentrated in environments where they encounter viruses, bacteria, and toxins, especially in the skin, nasal mucosa, lungs, airways, gastrointestinal tract, and meninges, to prevent their entry into the human body. Once SARS-CoV-2 enters the host, it stimulates one of the mast cells, together with pre-existing innate immune cells that form a defensive barrier in the submucosa of the respiratory tract and nasal cavities against pathogenic microorganisms. The roles of mast cells in SARS-CoV-2-induced hyperinflammation and cytokine storms have recently been one of the hot topics in the literature. Physicians should keep in mind the mast cells' role in cytokine release syndrome and related manifestations of COVID-19 disease. Mast cell-targeting therapies (e.g., H1 and H2 receptor antagonists) can reduce the severity and course of the disease when used after complications associated with COVID-19 are suspected or seen.

Autophagy in SARS-CoV-2 infection

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) orchestrates host factors to remodel endomembrane compartments for various steps of the infection cycle. SARS-CoV-2 also intimately intersects with the catabolic autophagy pathway during infection. In response to virus infection, autophagy acts as an innate defensive system by delivering viral components/particles to lysosomes for degradation. Autophagy also elicits antiviral immune responses. SARS-CoV-2, like other positive-stranded RNA viruses, has evolved various mechanisms to escape autophagic destruction and to hijack the autophagic machinery for its own benefit. In this review, we will focus on how the interplay between SARS-CoV-2 viral proteins and autophagy promotes viral replication and transmission. We will also discuss the pathogenic effects of SARS-CoV-2-elicited autophagy dysregulation and pharmacological interventions targeting autophagy for COVID-19 treatment.

Time evolution of cytokine profiles associated with mortality in COVID-19 hospitalized patients

Background

High cytokine levels have been associated with severe COVID-19 disease. Although many cytokine studies have been performed, not many of them include combinatorial analysis of cytokine profiles through time. In this study we investigate the association of certain cytokine profiles and its evolution, and mortality in SARS-CoV2 infection in hospitalized patients.

Methods

Serum concentration of 45 cytokines was determined in 28 controls at day of admission and in 108 patients with COVID-19 disease at first, third and sixth day of admission. A principal component analysis (PCA) was performed to characterize cytokine profiles through time associated with mortality and survival in hospitalized patients.

Results

At day of admission non-survivors present significantly higher levels of IL-1α and VEGFA (PC3) but not through follow up. However, the combination of HGF, MCP-1, IL-18, eotaxine, and SCF (PC2) are significantly higher in non-survivors at all three time-points presenting an increased trend in this group through time. On the other hand, BDNF, IL-12 and IL-15 (PC1) are significantly reduced in non-survivors at all time points with a decreasing trend through time, though a protective factor. The combined mortality prediction accuracy of PC3 at day 1 and PC1 and PC2 at day 6 is 89.00% (p<0.001).

Conclusions

Hypercytokinemia is a hallmark of COVID-19 but relevant differences between survivors and non-survivors can be early observed. Combinatorial analysis of serum cytokines and chemokines can contribute to mortality risk assessment and optimize therapeutic strategies. Three clusters of cytokines have been identified as independent markers or risk factors of COVID mortality.

Relapse or worsening of chronic spontaneous urticaria during SARS-CoV-2 infection and vaccination in children: A telemedicine follow-up

BACKGROUND

Chronic urticaria (CU), characterized by daily wheals and/or angioedema lasting more than 6 weeks, is a common skin disease. CU is classified as spontaneous or inducible. Because of Coronavirus Disease-19 (COVID-19) pandemic, face-to-face visits were reduced, and many centers started remote consultations to minimize hospital admissions and risk for viral diffusion. Telemedicine became a valuable tool for evaluating and monitoring patients with chronic diseases, such as CU. This study aims to evaluate the effectiveness of telemedicine as a means for the follow-up of patients with chronic spontaneous urticaria (CSU) during the COVID-19 pandemic. In particular, we collected data related to CSU evolution and treatment by remote consultation. Moreover, we specifically investigated the impact of SARS-CoV-2 infection or vaccination on CSU in relapsing or worsening of such a disease.

METHODS

The electronic charts were reviewed for patients diagnosed with CSU, who were referred to the allergy unit of Meyer Children's Hospital, Florence. For each patient, a review of demographic characteristics, diagnostic workup, efficacy, and tolerability of the treatment was performed. Patients with a physical agent triggering CU were excluded from the study. Disease activity was monitored using the Urticaria Activity Score (UAS7). In addition, when the COVID-19 pandemic started, follow-up continued through telemedicine after an initial face-to-face visit when possible. Approximately 1 year after the diagnosis of CSU, patients were recontacted to investigate whether they had experienced a relapse or worsening of urticaria during a possible COVID-19 or immediately after receiving a COVID-19 vaccine.

RESULTS

From January 2020 to March 2021, 84 cases of CSU were identified, with 71 (84.5%) of these being evaluated via televisit (remote consultation). During the remote follow-up period, 38/71 (53.5%) patients who were evaluated via televisit recovered completely from CSU, while 24 (33.8%) made therapy adjustments, and 9 (12.7%) had to discontinue follow-up through remote visits and return to face-to-face visits. In February 2022, we recontacted the 71 patients with CSU, and 50 (70.4%) of them answered by phone call interview. Four (19.2%) of the 26 patients who had COVID-19 showed CSU relapse, while 1 (3.8%) had a CSU worsening. Instead, 1 (3.8%) patient of the 26 who were vaccinated had a relapse of CSU, and 1 (3.8%) had a worsening of CSU, both after the first dose.

CONCLUSION

Our data showed that telemedicine can be an effective tool for the follow-up of patients with CSU. Moreover, COVID-19, as well as COVID-19 vaccination, may trigger CSU relapse or worsening, but both are unspecific triggers, and urticaria shows a very short duration in most cases.

Prophylactic Effects of Purple Shoot Green Tea on Cytokine Immunomodulation through Scavenging Free Radicals and NO in LPS-Stimulated Macrophages

Polyphenols and flavonoids from non-fermented green tea and fully-fermented black tea exhibit antioxidant abilities that function as natural health foods for daily consumption. Nonetheless, evidence regarding prophylactic effects of purple shoot tea on immunomodulation remains scarce. We compared the immunomodulatory effects of different tea processes on oxidative stress and cytokine expressions in lipopolysaccharide (LPS)-stimulated macrophages. Major constituents of four tea products, Taiwan Tea Experiment Station No.12 (TTES No. 12) black and green tea and purple shoot black and purple shoot green tea (TB, TG, PB and PG, respectively), were analyzed to explore the prophylactic effects on expressions of free radicals, nitric oxide (NO), monocyte chemoattractant protein-1 (MCP-1), interleukin 6 (IL-6) and tumor necrosis factor α (TNF-α) in LPS-activated RAW264.7 cell models. PG contained abundant levels of total polyphenols, flavonoids, condensed tannins and proanthocyanidins (371.28 ± 3.83; 86.37 ± 1.46; 234.67 ± 10.1; and 24.81 ± 0.75 mg/g, respectively) contributing to excellent free radical scavenging potency. In both the LPS-activated inflammation model and the prophylactic model, all tea extracts suppressed NO secretion in a dose-dependent manner, especially for PG. Intriguingly, most tea extracts enhanced expressions of IL-6 in LPS-stimulated macrophages, except PG. However, all teas disrupted downstream transduction of chemoattractant MCP-1 for immune cell trafficking. In the prophylactic model, all teas inhibited inflammatory responses by attenuating expressions of IL-6 and TNF-α in a dose-dependent manner, especially for TG and PG. Our prophylactic model demonstrated PG exerts robust effects on modulating LPS-induced cytokine expressions of MCP-1, IL-6 and TNF-α through scavenging free radicals and NO. In light of the prophylactic effects on LPS-related inflammation, PG effectively scavenges free radicals to modulate cytokine cascades that could serve as a functional beverage for immunomodulation.

COVID-19 infection rate after urgent versus elective total hip replacement among unvaccinated individuals: A multicenter prospective cohort amid the COVID-19 pandemic

Background

Due to the COVID-19 pandemic, hospitals have become unsafe for patients as potential sources of virus transmission. This study aims to determine the COVID-19 infection rate after primary total hip arthroplasty (THA) among unvaccinated patients. THA patients undergoing elective or traumatic (urgent) THA were compared regarding COVID-19 contraction.

Methods

Primary THA patients were prospectively followed from three hospitals in *two great cities* of the country between April 2020 to August 2021. If the patient had suspected COVID-19 symptoms, had a SARS-CoV-2 PCR test from nasopharyngeal and oropharyngeal swabs and/or chest CT scan.

Results

Finally, information was received from 436 patients, including 345 (79.1%) elective and 91 (20.9%) traumatic THAs. Eight patients (1.8%) contracted COVID-19 within a month after THA discharge, and two died due to COVID-19. There was no statistical difference between COVID-19 disease and type of surgery (elective 1.4% versus traumatic 3.3%, P = 0.24). Women (Odds ratio (95% CI) = 8.5 (2.1–35.2), P = 0.01) and those who have heart disease (Odds ratio with Haldane-Anscombe correction ≈ 14.0, P = 0.01) were more likely to contract COVID-19 postoperatively.

Conclusion

In both elective and urgent cases of THA, researchers found that there is not a high risk of contracting the virus during the peri-surgery period. Urgent THA surgeries are comparable to elective THA-with those strict pre-elective surgery protocols-in terms of COVID-19 risk of infection from the hospital stay if appropriate health protocols are followed.

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The COVID-19 pandemic has made hospitals unsafe for elective surgeries.

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Eight patients (from 491, 1.8%) were infected with COVID-19 within a month of THA.

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Four were hospitalized due to severe symptoms.

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Three of 91 traumatic (3.3%) and five among 345 elective cases (1.4%) were infected.

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COVID-19 incidence is two-fold higher in urgent THA patients, but insignificant.

Connecting the Dots in Emerging Mast Cell Research: Do Factors Affecting Mast Cell Activation Provide a Missing Link between Adverse COVID-19 Outcomes and the Social Determinants of Health?

Evidence continues to emerge that the social determinants of health play a role in adverse outcomes related to COVID-19, including increased morbidity and mortality, increased risk of long COVID, and vaccine adverse effects. Therefore, a more nuanced understanding of the biochemical and cellular pathways of illnesses commonly associated with adverse social determinants of health is urgently needed. We contend that a commitment to understanding adverse outcomes in historically marginalized communities will increase community-level confidence in public health measures. Here, we synthesize emerging literature on mast cell disease, and the role of mast cells in chronic illness, alongside emerging research on mechanisms of COVID illness and vaccines. We propose that a focus on aberrant and/or hyperactive mast cell behavior associated with chronic underlying health conditions can elucidate adverse COVID-related outcomes and contribute to the pandemic recovery. Standards of care for mast cell activation syndrome (MCAS), as well as clinical reviews, experimental research, and case reports, suggest that effective and cost-efficient remedies are available, including antihistamines, vitamin C, and quercetin, among others. Primary care physicians, specialists, and public health workers should consider new and emerging evidence from the biomedical literature in tackling COVID-19. Specialists and researchers note that MCAS is likely grossly under-diagnosed; therefore, public health agencies and policy makers should urgently attend to community-based experiences of adverse COVID outcomes. It is essential that we extract and examine experiential evidence of marginalized communities from the broader political–ideological discourse.

Post-COVID Syndrome: The Research Progress in the Treatment of Pulmonary sequelae after COVID-19 Infection

Post-COVID syndrome or long COVID is defined as the persistence of symptoms after confirmed SARS-CoV-2 infection, the pathogen responsible for coronavirus disease. The content herein presented reviews the reported long-term consequences and aftereffects of COVID-19 infection and the potential strategies to adopt for their management. Recent studies have shown that severe forms of COVID-19 can progress into acute respiratory distress syndrome (ARDS), a predisposing factor of pulmonary fibrosis that can irreversibly compromise respiratory function. Considering that the most serious complications are observed in the airways, the inhalation delivery of drugs directly to the lungs should be preferred, since it allows to lower the dose and systemic side effects. Although further studies are needed to optimize these techniques, recent studies have also shown the importance of in vitro models to recreate the SARS-CoV-2 infection and study its sequelae. The information reported suggests the necessity to develop new inhalation therapies in order to improve the quality of life of patients who suffer from this condition.

COVID-19 Vaccination in Patients With Malignancy; A Systematic Review and Meta-Analysis of the Efficacy and Safety

Background

Data on the efficacy and safety of COVID-19 vaccines in patients with malignancy are immature. In this paper, we assessed the literature involving the use of COVID-19 vaccines in cancer patients and reported the seroconversion rates as the main outcome and severity of COVID-19 infection and side effects following COVID-19 vaccination as the secondary outcomes.

Methods

A systematic review with meta-analysis was performed. Searches were conducted in electronic websites, databases, and journals, including Scopus, PubMed, Embase, and Web of Science from January 01, 2019, to November 30, 2021. Studies reporting data on the safety and efficacy of COVID vaccine in cancer patients using any human samples were included. The risk of bias was assessed using the NEWCASTLE-OTTAWA scale in the included studies.

Results

A total of 724 articles were identified from databases, out of which 201 articles were duplicates and were discarded. Subsequently, 454 articles were excluded through initial screening of the titles and abstracts. Moreover, 41 studies did not report the precise seroconversion rate either based on the type of cancer or after injection of a second dose of COVID vaccine. Finally, 28 articles met all the inclusion criteria and were included in this systematic review. The overall seroconversion rates after receiving a second dose of COVID-19 vaccine, based on type of cancer were 88% (95% CI, 81%-92%) and 70% (95% CI, 60%-79%) in patients with solid tumors and hematologic malignancies, respectively.

Conclusion

Overall, we conclude that vaccination against COVID-19 in patients with active malignancies using activated and inactivated vaccines is a safe and tolerable procedure that is also accompanied by a high efficacy.

Hyper/neuroinflammation in COVID-19 and suicide etiopathogenesis: Hypothesis for a nefarious collision?

Accumulating scientific and clinical evidence highlighted pathological hyperinflammation as a cardinal feature of SARS-CoV-2 infection and acute COVID-19 disease. With the emergence of long COVID-19 syndrome, several chronic health consequences, including neuropsychiatric sequelae, have gained attention from the public and medical communities. Since inflammatory mediators have also been accredited as putative biomarkers of suicidal ideations and behaviors, hyper- and neuroinflammation might share some colliding points, overlapping and being interconnected in the context of COVID-19. This review aims to provide a summary of current knowledge on the molecular and cellular mechanisms of COVID-19-associated hyper/neuroinflammation with focus on their relevance to the inflammatory hypothesis of suicide development. Subsequently, strategies to alleviate COVID-19 hyper/neuroinflammation by immunomodulatory agents (many of which at experimental stages) as well as psychopharmacologic/psychotherapeutic approaches are also mentioned. While suicide risk in COVID-19 survivors - until now little known - needs further analysis through longitudinal studies, current observations and mechanistic postulates warrant additional attention to this possibly emerging mental health concern.

Neutrophil Functional Heterogeneity and Implications for Viral Infections and Treatments

Evidence suggests that neutrophils exert specialized effector functions during infection and inflammation, and that these cells can affect the duration, severity, and outcome of the infection. These functions are related to variations in phenotypes that have implications in immunoregulation during viral infections. Although the complexity of the heterogeneity of neutrophils is still in the process of being uncovered, evidence indicates that they display phenotypes and functions that can assist in viral clearance or augment and amplify the immunopathology of viruses. Therefore, deciphering and understanding neutrophil subsets and their polarization in viral infections is of importance. In this review, the different phenotypes of neutrophils and the roles they play in viral infections are discussed. We also examine the possible ways to target neutrophil subsets during viral infections as potential anti-viral treatments.

The Utility of Laboratory Parameters for Cardiac Inflammation in Heart Failure Patients Hospitalized with SARS-CoV-2 Infection

COVID-19 has been associated with cardiovascular consequences, including myocardial infarction, thromboembolic events, arrhythmia, and heart failure. Numerous overlapping mechanisms, such as the IL-6 dependent cytokine storm and unopposed angiotensin II stimulation, could be responsible for these consequences. Cardiac damage is hypothesized to be a consequence of the direct viral infection of cardiomyocytes, resulting in increased metabolic demand, immunological activation, and microvascular dysfunction. Patients with pre-existing chronic heart failure are therefore at increased risk of decompensation, further heart damage, and significant health deterioration. Based on the aforementioned assumptions, we developed a study aiming to provide a detailed description of changes in biological parameters and cardiac injury markers of patients with heart failure and SARS-CoV-2 infection by correlating them with the clinical presentation and COVID-19 vaccination status, to predict the probability of ICU admission based on their initial hospital presentation. A two-year retrospective study was performed on heart failure patients with a history of SARS-CoV-2 infection and detailed records of biological biomarkers; a total of 124 eligible patients with COVID-19 and 236 without COVID-19 were recruited. Patients with heart failure and SARS-CoV-2 infection had significantly elevated baseline biological parameters and cardiac markers compared to those without COVID-19. Several cardiac injury markers were identified as significant independent risk factors for ICU admission: CK-MB (HR = 4.1, CI[2.2–6.9]), myoglobin (HR = 5.0, CI[2.3–7.8]), troponin-I (HR = 7.1[4.4–9.6]) troponin-T (HR = 4.9, CI[1.7–7.4]). The elevation of a basic panel of acute inflammation markers (CRP, IL-6, fibrinogen), D-dimers, and BNP was also a significant risk factor. The follow-up of survivors at four weeks after viral clearance determined a worsened clinical picture by NYHA classification, worsened cardiac ultrasound findings, and a mild improvement in cardiac and inflammatory markers. Increased levels of myocardial damage parameters in association with cardiac ultrasound findings and basic inflammatory markers may enable early risk assessment and triage in hospitalized heart failure patients infected with SARS-CoV-2.

Post-mortem Findings of Inflammatory Cells and the Association of 4-Hydroxynonenal with Systemic Vascular and Oxidative Stress in Lethal COVID-19

A recent comparison of clinical and inflammatory parameters, together with biomarkers of oxidative stress, in patients who died from aggressive COVID-19 and survivors suggested that the lipid peroxidation product 4-hydroxynonenal (4-HNE) might be detrimental in lethal SARS-CoV-2 infection. The current study further explores the involvement of inflammatory cells, systemic vascular stress, and 4-HNE in lethal COVID-19 using specific immunohistochemical analyses of the inflammatory cells within the vital organs obtained by autopsy of nine patients who died from aggressive SAR-CoV-2 infection. Besides 4-HNE, myeloperoxidase (MPO) and mitochondrial superoxide dismutase (SOD2) were analyzed alongside standard leukocyte biomarkers (CDs). All the immunohistochemical slides were simultaneously prepared for each analyzed biomarker. The results revealed abundant 4-HNE in the vital organs, but the primary origin of 4-HNE was sepsis-like vascular stress, not an oxidative burst of the inflammatory cells. In particular, inflammatory cells were often negative for 4-HNE, while blood vessels were always very strongly immunopositive, as was edematous tissue even in the absence of inflammatory cells. The most affected organs were the lungs with diffuse alveolar damage and the brain with edema and reactive astrocytes, whereas despite acute tubular necrosis, 4-HNE was not abundant in the kidneys, which had prominent SOD2. Although SOD2 in most cases gave strong immunohistochemical positivity similar to 4-HNE, unlike 4-HNE, it was always limited to the cells, as was MPO. Due to their differential expressions in blood vessels, inflammatory cells, and the kidneys, we think that SOD2 could, together with 4-HNE, be a potential link between a malfunctioning immune system, oxidative stress, and vascular stress in lethal COVID-19.

Cellular Immunology and COVID-19

In "Cellular Immunology and COVID-19" (a Special Issue of Cells), a panel of leading scientists provides an exhaustive overview of the different aspects of the immune mechanisms underlying COVID-19 [...].

Hypersensitivity may be involved in severe COVID-19

Background

Deaths attributed to Coronavirus Disease 2019 (COVID‐19) are mainly due to severe hypoxemic respiratory failure. Although the inflammatory storm has been considered the main pathogenesis of severe COVID‐19, hypersensitivity may be another important mechanism involved in severe cases, which have a perfect response to corticosteroids (CS).

Method

We detected the serum level of anti‐SARS‐CoV‐2–spike S1 protein‐specific IgE (SP‐IgE) and anti‐SARS‐CoV‐2 nucleocapsid protein‐specific IgE (NP‐IgE) in COVID‐19. Correlation of levels of specific IgE and clinical severity were analysed. Pulmonary function test and bronchial provocation test were conducted in early convalescence of COVID‐19. We also obtained histological samples via endoscopy to detect the evidence of mast cell activation.

Result

The levels of serum SP‐IgE and NP‐IgE were significantly higher in severe cases, and were correlated with the total lung severity scores (TLSS) and the PaO₂/FiO₂ ratio. Nucleocapsid protein could be detected in both airway and intestinal tissues, which was stained positive together with activated mast cells, binded with IgE. Airway hyperresponsiveness (AHR) exists in the early convalescence of COVID‐19. After the application of CS in severe COVID‐19, SP‐IgE and NP‐IgE decreased, but maintained at a high level.

Conclusion

Hypersensitivity may be involved in severe COVID‐19.