Hypercytokinemia and Pathogen-Host Interaction in COVID-19

The anaphylatoxin C5a: Structure, function, signaling, physiology, disease, and therapeutics

The complement system is one of the oldest known tightly regulated host defense systems evolved for efficiently functioning cell-based immune systems and antibodies. Essentially, the complement system acts as a pivot between the innate and adaptive arms of the immune system. The complement system collectively represents a cocktail of ∼50 cell-bound/soluble glycoproteins directly involved in controlling infection and inflammation. Activation of the complement cascade generates complement fragments like C3a, C4a, and C5a as anaphylatoxins. C5a is the most potent proinflammatory anaphylatoxin, which is involved in inflammatory signaling in a myriad of tissues. This review provides a comprehensive overview of human C5a in the context of its structure and signaling under several pathophysiological conditions, including the current and future therapeutic applications targeting C5a.

Puerarin: A Potential Therapeutic for Colon Adenocarcinoma (COAD) Patients Suffering From SARS-CoV-2 Infection

Patients with colonic adenocarcinoma (COAD) are at relatively high risk of SARS-CoV-2 infection. However, there is a lack of medical strategies to treat COVID-19/COAD comorbidity. Puerarin, a natural product, is a known antiviral, antitumor, and immunomodulatory effect. Therefore, we hypothesised that puerarin could be used to treat COVID-19/COAD patients. Based on network pharmacology and bioinformatics analysis, the potential targets and pharmacological mechanisms of puerarin in COVID-19/COAD were identified. By intersecting therapeutic target genes for puerarin, COVID-19-related genes and COAD-related genes, 42 target genes of puerarin that could potentially treat COVID-19/COAD comorbidity were obtained. By using the 42 potential target genes to construct the protein-protein interaction (PPI) network, we obtained five core target genes, namely RELA, BCL2, JUN, FOS, and MAPK1. The results of bioinformatics analysis revealed that puerarin could be able to treat COVID-19/COAD comorbidity through apoptosis, antiviral, antioxidant, NF-κB signaling pathway, MAPK signaling pathway, IL-17 signaling pathway, TNF signaling pathway, and HIF-1 signaling pathway etc. This study found that puerarin has the potential to treat COVID-19/COAD patients and that the therapeutic target genes obtained in the study may provide clues for the treatment of COVID19/COAD comorbidity.

The role of angiotensin-converting enzyme 2 (ACE2) genetic variations in COVID-19 infection: a literature review

Background

The angiotensin-converting enzyme-2 (ACE2) is recognized to be the fundamental receptor of severe acute respiratory syndrome coronavirus-2 (SARS-CoV2), responsible for the worldwide Coronavirus Disease-2019 (COVID-19) epidemic. However, genetic differences between people besides racial considerations and their relation to disease susceptibility are still not fully elucidated.

Main body

To uncover the role of ACE2 in COVID-19 infection, we reviewed the published studies that explore the association of COVID-19 with the functional characteristics of ACE2 and its genetic variations. Notably, emerging studies tried to determine whether the ACE2 variants and/or expression could be associated with SARS-CoV/SARS-CoV2 have conflicting results. Some researchers investigated the potential of "population-specific" ACE2 genetic variations to impact the SARS-CoV2 vulnerability and suggested no ethnicity enrichment for ACE2 polymorphisms that could influence SARS-CoV2 S-protein binding. At the same time, some studies use data mining to predict several ACE2 variants that could enhance or decline susceptibility to SARS-CoV. On the other hand, fewer studies revealed an association of ACE2 expression with COVID-19 outcome reporting higher expression levels of ACE2 in East Asians.

Conclusions

ACE2 gene variants and expression may modify the deleterious consequences of SARS-CoV2 to the host cells. It is worth noting that apart from the differences in gene expression and the genetic variations of ACE2, many other environmental and/or genetic factors could modify the disease outcome, including the genes for the innate and the adaptive immune response.

COVID-19: The question of genetic diversity and therapeutic intervention approaches

Coronavirus disease 2019 (COVID-19), caused by the Severe Acute Respiratory Syndrome Coronavirus type 2 (SARS-CoV-2), is the largest pandemic in modern history with very high infection rates and considerable mortality. The disease, which emerged in China's Wuhan province, had its first reported case on December 29, 2019, and spread rapidly worldwide. On March 11, 2020, the World Health Organization (WHO) declared the COVID-19 outbreak a pandemic and global health emergency. Since the outbreak, efforts to develop COVID-19 vaccines, engineer new drugs, and evaluate existing ones for drug repurposing have been intensively undertaken to find ways to control this pandemic. COVID-19 therapeutic strategies aim to impair molecular pathways involved in the virus entrance and replication or interfere in the patients' overreaction and immunopathology. Moreover, nanotechnology could be an approach to boost the activity of new drugs. Several COVID-19 vaccine candidates have received emergency-use or full authorization in one or more countries, and others are being developed and tested. This review assesses the different strategies currently proposed to control COVID-19 and the issues or limitations imposed on some approaches by the human and viral genetic variability.

ACE2 and TMPRSS2 SNPs as Determinants of Susceptibility to, and Severity of, a COVID-19 Infection

Background: Genetic risk factors may be related to the infectivity and severity of SARS-CoV-2 infection. Angiotensin-converting enzyme 2 (ACE2) and host transmembrane serine protease (TMPRSS2) have key role in viral cell entrance and priming.

Methods: This case-control study on 147 healthy controls and 299 COVID-19 patients identified potential determinants and risk factors, including gene polymorphism involved in the severity (mild, moderate, severe) of COVID-19 disease defined by CORAD radiological criteria.

Results: The ACE2 s2285666 and TMPRSS2 rs12329760 SNPs were significantly linked with COVID-19 disease severity, as were certain co-morbidities (hypertension, heart disease) and laboratory parameters. Both SNPs were amongst the highest predictors of disease severity: TMPRSS2 rs12329760 CT + TT [odds ratio (95% CI) 17.6 (5.1–61.10), ACE2 rs2285666 CT + TT 9.9 (3.2–30.9), both p < 0.001]. There was an increase in the expression of genotype frequencies of ACE2 rs2285666 and TMPRSS2 rs1232976 (TT), (CT + TT), and (T) allele in severe COVID-19 group compared to control and mild groups. Disease severity was also linked to elevated CRP, ferritin and D-dimer, and lower lymphocytes and platelet count (all p < 0.001).

Conclusion: ACE2 rs2285666 and TMPRSS2 rs12329760 SNPs, in addition to lymphocyte count, CRP, D-dimers, ferritin, and hypertension, are predictors of COVID-19 disease severity.

Determination role of some biomarkers tests for severe SARS-COV-2 infections in babylon province/IRAQ

In a series of 30 SARS-COV-2 infected patients whom clinically proven as severe pulmonary infection form. These were found with male/female ratio of 1:1. The age range of below 50 years old account for 60% and those of above 50 years old constitute the remaining 40%. They were the residents of Merjan Teaching Hospital/ Babylon Province/Iraq, to the period of March to April 2021 and primary screen by PCR for Sars-cov-2 RNA genes, in public health central laboratory found to be positive. The over- all laboratory investigation were; D –dimer, Ferritin, LDH, acute phase reactant C, and IL6. LDH was tempted to probe the immune mediated pulmonary tissue injury (367.48 U/L.), ferritin response may indicate hemolytic and acute phase reactant expressed as hyper-inflammation (331.1 ng/L.). |The D-dimer shed a light on the fibrino-lytic responses (6049 ng/L.) post to the immune-thrombotic overreactions, where IL6 levels give a clue to the state of hyper-cytokinemia (171.92 pg/L.). The overall immune status of these patients was as; Hyper-inflammatory and immune overreaction. The inflammatory and immune herd plots were of skewed distribution types.

Immunity Profiling of COVID-19 Infection, Dynamic Variations of Lymphocyte Subsets, a Comparative Analysis on Four Different Groups

Background: A novel coronavirus (SARS-CoV-2)-induced pneumonia (COVID-19) emerged in December 2019 in China, spreading worldwide. The aim of the present investigation was to evaluate the immunological response and the clinical subset of peripheral lymphocyte subset alteration in COVID-19 infection. Methods: the study was conducted on four different clinical groups (n = 4; total n = 138). Each individual was assigned to different groups based on specific criteria evaluated at the admission such as fever, dyspnea, arterial blood gas analysis (ABG), oral-nasopharyngeal swab/RT-PCR, and thoracic CT-scan. Treatment was performed only after blood samples were collected from each patient (PP and PP) at day 1. The blood samples were analyzed and tested the same day (CBC and Flowcytometry). The positive–positive group (PP n = 45; F = 18/ M = 27; median age = 62.33), comprised individuals affected by COVID-19 who showed fever, dyspnea (ABG = pO2 < 60), confirmed positive by oral-nasopharyngeal swab/RT-PCR and with CT-scan showing ground-glass opacities. The negative–positive (NP; n = 37; F = 11/M = 26; median age = 75.94) or “COVID-like” group comprised individuals with fever and dyspnea (ABG = pO2 < 60), who tested negative to nasopharyngeal swab/RT-PCR, with CT-scans showing ground-glass opacities in the lungs. The negative–affected group (NA; n = 40; F = 14/M = 26; median age = 58.5) included individuals negative to COVID-19 (RT-PCR) but affected by different chronic respiratory diseases (the CT-scans didn’t show ground-glass opacities). Finally, the negative–negative group (NN; n = 16; F = 14/M = 2) included healthy patients (NN; n = 16; median age = 42.62). Data and findings were collected and compared. Results: Lymphocytes (%) cells showed a decline in COVID-19 patients. The subsets showed a significant association with the inflammatory status in COVID-19, especially with regard to increased neutrophils, T-killer, T-active, T-suppressor, and T-CD8+CD38+ in individuals belong to the either COVID-19 and Covid-like NP group. Conclusions: Peripheral lymphocyte subset alteration was associated with the clinical characteristics and progression of COVID-19. The level of sub-set cells T-lymphocytes (either high or low) and B-lymphocytes could be used as an independent predictor for COVID-19 severity and treatment efficacy.

IFN-γ Drives TNF-α Hyperproduction and Lethal Lung Inflammation during Antibiotic Treatment of Postinfluenza Staphylococcus aureus Pneumonia

Inflammatory cytokine storm is a known cause for acute respiratory distress syndrome. In this study, we have investigated the role of IFN-γ in lethal lung inflammation using a mouse model of postinfluenza methicillin-resistant Staphylococcus aureus (MRSA) pneumonia. To mimic the clinical scenario, animals were treated with antibiotics for effective bacterial control following MRSA superinfection. However, antibiotic therapy alone is not sufficient to improve survival of wild-type animals in this lethal acute respiratory distress syndrome model. In contrast, antibiotics induce effective protection in mice deficient in IFN-γ response. Mechanistically, we show that rather than inhibiting bacterial clearance, IFN-γ promotes proinflammatory cytokine response to cause lethal lung damage. Neutralization of IFN-γ after influenza prevents hyperproduction of TNF-α, and thereby protects against inflammatory lung damage and animal mortality. Taken together, the current study demonstrates that influenza-induced IFN-γ drives a stepwise propagation of inflammatory cytokine response, which ultimately results in fatal lung damage during secondary MRSA pneumonia, despite of antibiotic therapy.

The role of human C5a as a non-genomic target in corticosteroid therapy for management of severe COVID19

Complement system plays a dual role; physiological as well as pathophysiological. While physiological role protects the host, pathophysiological role can substantially harm the host, by triggering several hyper-inflammatory pathways, referred as "hypercytokinaemia". Emerging clinical evidence suggests that exposure to severe acute respiratory syndrome coronavirus-2 (SARS-CoV2), tricks the complement to aberrantly activate the "hypercytokinaemia" loop, which significantly contributes to the severity of the COVID19. The pathophysiological response of the complement is usually amplified by the over production of potent chemoattractants and inflammatory modulators, like C3a and C5a. Therefore, it is logical that neutralizing the harmful effects of the inflammatory modulators of the complement system can be beneficial for the management of COVID19. While the hunt for safe and efficacious vaccines were underway, polypharmacology based combination therapies were fairly successful in reducing both the morbidity and mortality of COVID19 across the globe. Repurposing of small molecule drugs as "neutraligands" of C5a appears to be an alternative for modulating the hyper-inflammatory signals, triggered by the C5a-C5aR signaling axes. Thus, in the current study, few specific and non-specific immunomodulators (azithromycin, colchicine, famotidine, fluvoxamine, dexamethasone and prednisone) generally prescribed for prophylactic usage for management of COVID19 were subjected to computational and biophysical studies to probe whether any of the above drugs can act as "neutraligands", by selectively binding to C5a over C3a. The data presented in this study indicates that corticosteroids, like prednisone can have potentially better selectively (Kd ∼ 0.38 μM) toward C5a than C3a, suggesting the positive modulatory role of C5a in the general success of the corticosteroid therapy in moderate to severe COVID19.

Is butyrate a natural alternative to dexamethasone in the management of CoVID-19?

Coronavirus disease 2019 (CoVID-19) caused by Severe Acute Respiratory Syndrome Coronavirus 2 has affected more than 100 million lives. Severe CoVID-19 infection may lead to acute respiratory distress syndrome and death of the patient, and is associated with hyperinflammation and cytokine storm. The broad spectrum immunosuppressant corticosteroid, dexamethasone, is being used to manage the cytokine storm and hyperinflammation in CoVID-19 patients. However, the extensive use of corticosteroids leads to serious adverse events and disruption of the gut-lung axis. Various micronutrients and probiotic supplementations are known to aid in the reduction of hyperinflammation and restoration of gut microbiota. The attenuation of the deleterious immune response and hyperinflammation could be mediated by short chain fatty acids produced by the gut microbiota. Butyric acid, the most extensively studied short chain fatty acid, is known for its anti-inflammatory properties. Additionally, butyric acid has been shown to ameliorate hyperinflammation and reduce oxidative stress in various pathologies, including respiratory viral infections. In this review, the potential anti-inflammatory effects of butyric acid that aid in cytokine storm depletion, and its usefulness in effective management of critical illness related to CoVID-19 have been discussed.

Comparative profile for COVID-19 cases from China and North America: Clinical symptoms, comorbidities and disease biomarkers

BACKGROUND

Large inter-individual and inter-population differences in the susceptibility to and outcome of severe acute respiratory syndrome coronavirus 2 or coronavirus disease 2019 (COVID-19) have been noted. Understanding these differences and how they influence vulnerability to infection and disease severity is critical to public health intervention.

AIM

To analyze and compare the profile of COVID-19 cases between China and North America as two regions that differ in many environmental, host and healthcare factors related to disease risk.

METHODS

We conducted a meta-analysis to examine and compare demographic information, clinical symptoms, comorbidities, disease severity and levels of disease biomarkers of COVID-19 cases from clinical studies and data from China (105 studies) and North America (19 studies).

RESULTS

COVID-19 patients from North America were older than their Chinese counterparts and with higher male: Female ratio. Fever, cough, fatigue and dyspnea were the most common clinical symptoms in both study regions (present in about 30% to 75% of the cases in both regions). Meta-analysis for the prevalence of comorbidities (such as obesity, hypertension, diabetes, cardiovascular diseases, chronic obstructive pulmonary disease, cancer, and chronic kidney diseases) in COVID-19 patients were all significantly more prevalent in North America compared to China. Comorbidities were positively correlated with age but at a significantly younger age range in China compared to North American. The most prevalent infection outcome was acute respiratory distress syndrome which was 2-fold more frequent in North America than in China. Levels of C-reactive protein were 4.5-fold higher in the North American cases than in cases from China.

CONCLUSION

The differences in the profile of COVID-19 cases from China and North America may relate to differences in environmental-, host- and healthcare-related factors between the two regions. Such inter-population differences-together with intra-population variability-underline the need to characterize the effect of health inequities and inequalities on public health response to COVID-19 and can assist in preparing for the re-emergence of the epidemic.

Inflammatory Cytokine: IL-17A Signaling Pathway in Patients Present with COVID-19 and Current Treatment Strategy

Coronavirus disease 2019 (COVID-19) is a globally communicable public health disease caused by severe acute respiratory syndrome coronavirus 2 (SARS‐CoV-2). Eradication of COVID-19 appears practically impossible but, therefore, more effective pharmacotherapy is needed. The deteriorated clinical presentation of patients with COVID-19 is mainly associated with hypercytokinemia due to notoriously elevated pro-inflammatory cytokines such as interleukin (IL)-1B, IL-6, IL-8, IL-17, granulocyte-macrophage colony-stimulating factor (GM-CSF), granulocyte colony-stimulating factor (G-CSF), interferon-γ-inducible protein (IP10), monocyte chemoattractant protein (MCP1), and tumor necrosis factor-α (TNFα), and is usually responsible for cytokine release syndrome. In the cytokine storm, up-regulation of T-helper 17 cell cytokine IL-17A, and maybe also IL-17F, is mostly responsible for the immunopathology of COVID-19 and acute respiratory distress syndrome. Herein, I meticulously review the exuberant polarization mechanism of naïve CD4⁺ T cells toward Th17 cells in response to SARS-CoV-2 infection and its associated immunopathological sequelae. I also, propose, for clinical benefit, targeting IL-17A signaling and the synergic inflammatory cytokine IL-6 to manage COVID-19 patients, particularly those presenting with cytokine storm syndrome.

COVID-19 susceptibility: potential of ACE2 polymorphisms

Background

Angiotensin-converting enzyme 2 (ACE2) is a metallopeptidase that primarily functions as a negative regulator of renin angiotensin system (RAS) by converting angiotensin II (Ang II) to angiotensin 1-7. Contrary to this, another RAS component, angiotensin-converting enzyme (ACE) catalyzes synthesis of Ang II from angiotensin I (Ang I) that functions as active compound in blood pressure regulation. This indicates importance of ACE/ACE2 level in regulating blood pressure by targeting Ang II. An outbreak of severe acute respiratory syndrome (SARS) highlighted the additional role of ACE2 as a receptor for SARS coronavirus (SARS-CoV) infection.

Main body of the abstract

ACE2 is a functional receptor for SARS-CoV and SARS-CoV-2. Activation of spike (S)-protein by either type II transmembrane serine proteases (TTSPs) or cathepsin-mediated cleavage initiates receptor binding and viral entry. In addition to TTSPs, ACE2 can also be trimmed by ADAM 17 (a disintegrin and metalloproteinase 17) that competes for the same receptor. Cleavage by TTSPs activates ACE2 receptor for binding, whereas ADAM17 releases extracellular fragment called soluble ACE2 (sACE2). Structural studies of both ACE2 and S-protein have found critical sites involved in binding mechanism. In addition to studies on structural motifs, few single-nucleotide polymorphism (SNPs) studies have been done to find an association between genetic variants and SARS susceptibility. Though no association was found in those reports, but seeing the non-reproducibility of SNP studies among different ethnic groups, screening of ACE2 SNPs in individual population can be undertaken.

Short conclusion

Thus, screening for novel SNPs focussing on recently identified critical regions of ACE2 can be targeted to monitor susceptibility towards coronavirus disease 2019 (COVID-19).