Association between mannose-binding lectin gene polymorphisms and susceptibility to severe acute respiratory syndrome coronavirus infection

Complement activity and autophagy are dysregulated in the lungs of patients with nonresolvable COVID-19 requiring lung transplantation

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-induced coronavirus disease 2019 (COVID-19) pandemic has challenged the current understanding of the complement cascade mechanisms of host immune responses during infection-induced nonresolvable lung disease. While the complement system is involved in opsonization and phagocytosis of the invading pathogens, uncontrolled complement activation also leads to aberrant autophagic response and tissue damage. Our recent study revealed unique pathologic and fibrotic signature genes associated with epithelial bronchiolization in the lung tissues of patients with nonresolvable COVID-19 (NR-COVID-19) requiring lung transplantation. However, there is a knowledge gap if complement components are modulated to contribute to tissue damage and the fibrotic phenotype during NR-COVID-19. We, therefore, aimed to study the role of the complement factors and their corresponding regulatory proteins in the pathogenesis of NR-COVID-19. We further examined the association of complement components with mediators of the host autophagic response. We observed significant upregulation of the expression of the classical pathway factor C1qrs and alternative complement factors C3 and C5a, as well as the anaphylatoxin receptor C5aR1, in NR-COVID-19 lung tissues. Of note, complement regulatory protein, decay accelerating factor (DAF; CD55) was significantly downregulated at both transcript and protein levels in the NR-COVID-19 lungs, indicating a dampened host protective response. Furthermore, we observed significantly decreased levels of the autophagy mediators PPARγ and LC3a/b, which was corroborated by decreased expression of factor P and the C3b receptor CR1, indicating impaired clearance of damaged cells that may contribute to the fibrotic phenotype in NR-COVID-19 patients. Thus, our study revealed previously unrecognized complement dysregulation associated with impaired cell death and clearance of damaged cells, which may promote NR-COVID-19 in patients, ultimately necessitating lung transplantation. The identified network of dysregulated complement cascade activity indicates the interplay of regulatory factors and the receptor-mediated modulation of host immune and autophagic responses as potential therapeutic targets for treating NR-COVID-19.

Differential Immunoregulation by Human Surfactant Protein A Variants Determines Severity of SARS-CoV-2-induced Lung Disease

COVID-19 remains a significant threat to public health globally. Infection in some susceptible individuals causes life-threatening acute lung injury (ALI/ARDS) and/or death. Human surfactant protein A (SP-A) is a C-type lectin expressed in the lung and other mucosal tissues, and it plays a critical role in host defense against various pathogens. The human SP-A genes ( SFTPA1 and SFTPA2 ) are highly polymorphic and comprise several common genetic variants, i.e., SP-A1 (variants 6A 2 , 6A 4 ) and SP-A2 (variants 1A 0 , 1A 3 ). Here, we elucidated the differential antiviral and immunoregulatory roles of SP-A variants in response to SARS-CoV-2 infection in vivo . Six genetically-modified mouse lines, expressing both hACE2 (SARS-CoV-2 receptor) and individual SP-A variants: (hACE2/6A 2 (6A 2 ), hACE2/6A 4 (6A 4 ), hACE2/1A 0 (1A 0 ), and hACE2/1A 3 (1A 3 ), one SP-A knockout (hACE2/SP-A KO (KO) and one hACE2/mouse SP-A (K18) mice, were challenged intranasally with 10 3 PFU SARS-CoV-2 or saline (Sham). Infected KO and 1A 0 mice had more weight loss and mortality compared to other mouse lines. Relative to other infected mouse lines, a more severe ALI was observed in KO, 1A 0 , and 6A 2 mice. Reduced viral titers were generally observed in the lungs of infected SP-A mice relative to KO mice. Transcriptomic analysis revealed an upregulation in genes that play central roles in immune responses such as MyD88 , Stat3 , IL-18 , and Jak2 in the lungs of KO and 1A 0 mice. However, Mapk1 was significantly downregulated in 6A 2 versus 1A 0 mice. Analysis of biological pathways identified those involved in lung host defense and innate immunity, including pathogen-induced cytokine, NOD1/2, and Trem1 signaling pathways. Consistent with the transcriptomic data, levels of cytokines and chemokines such as G-CSF, IL-6 and IL-1β were comparatively higher in the lungs and sera of KO and 1A 0 mice with the highest mortality rate. These findings demonstrate that human SP-A variants differentially modulate SARS-CoV-2-induced lung injury and disease severity by differentially inhibiting viral infectivity and regulating immune-related gene expressions.

The effect of the MBL2 gene rs1800450 variant on COVID-19 development in Turkish patients

The coronavirus disease 2019 (COVID-19) is a recent pandemic occurring worldwide due to the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus, spreading mainly through large respiratory droplets or maybe through other transmission routes. The human genome has the most varied immune response genes correlated with infectious diseases. Genetic variants of mannose-binding lectin 2 (MBL2), an immunomodulatory gene, were associated with the risk, severity, and frequency of viral infections. In the present study, we hypothesized that the MBL2 gene rs1800450 variant could be associated with the development of COVID-19 disease in a Turkish population. Ninety-eight COVID-19 patients and 98 healthy, ethnically matched controls were studied. We isolated genomic DNA from whole blood and analyzed the MBL2 rs1800450 using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. Associations were analyzed with the SPSS 20 statistical software. We found that MBL2 rs1800450 genotype distribution was significantly different between patients and controls. The patients had a higher MBL2 rs1800450 AA genotype than the controls had (4.94% in patients vs. 3.12% in controls, p = 0.006). The subjects carrying AA genotype had a 10.83-fold increased risk for COVID-19 disease (OR = 10.83, %95 CI = 1.359-86.349). We could not detect any significant difference between the COVID-19 patients and healthy controls in allele frequencies. Our findings demonstrated that the MBL2 rs1800450 BB genotype might increase the susceptibility to COVID-19 disease in the Turkish population. We suggest further studies with a larger sample size and other ethnic populations.

High production MBL2 polymorphisms protect against COVID-19 complications in critically ill patients: A retrospective cohort study

Mannose-binding lectin (MBL) binds to SARS-CoV-2, inhibits infection of susceptible cells, and activates the complement system via the lectin pathway. In this study, we investigated the association of MBL2 polymorphisms with the risk of hospitalization and clinical worsening in patients with COVID-19. A total of 550 patients with COVID-19 were included (94 non-hospitalized and 456 hospitalized). Polymorphisms in MBL2 exon 1 (codons 52, 54 and 57) and promoter region (-550, -221, and +4) were determined by real-time PCR. MBL and complement proteins were measured by Luminex. A higher frequency of the H/H genotype and the HYPA haplotype was observed in non-hospitalized patients when compared to hospitalized. In addition, critically ill patients carrying haplotypes associated with high MBL levels (HYPA/HYPA + HYPA/LYPA + HYPA/LYQA + LYPA/LYQA + LYPA/LYPA + LYQA/LYQA + LXPA/HYPA + LXPA/LYQA + LXPA/LYPA) were protected against lower oxygen saturation levels (P = 0.02), use of invasive ventilation use (P = 0.02, OR 0.38), and shock (P = 0.01, OR 0.40), independent of other potential confounders adjusted by multivariate analysis. Our results suggest that variants in MBL2 associated with high MBL levels may play a protective role in the clinical course of COVID-19.

COVID-19 host genetic risk study conducted at community pharmacies: Implications for public health, research and pharmacists' scope of practice

Community pharmacists serve a large, diverse population of patients, resulting in the potential to utilize community pharmacies as recruitment sites for clinical research. Beyond traditional roles as one of the most accessible health care professionals in the US healthcare system, pharmacists have played a major role in the response to the COVID-19 pandemic, administering hundreds of thousands of vaccines and tests. However, less emphasis is placed on the ability to leverage community pharmacies as research-focused partners for clinical studies. In this study, we demonstrate the feasibility and workflow of recruiting study participants from community pharmacies and confirm genetic markers of COVID-19 susceptibility. Specific genetic markers include those associated with COVID-19 infection risk (ACE2, TMEM27, and RAVER1), difficulty breathing (NOTCH4), and hospitalization (OAS3). In addition, collaboration with a clinical laboratory allowed for a more seamless consenting process without substantial training needs or workflow disruption at the community pharmacy site. The COVID-19 pandemic has demonstrated that the expansion of pharmacists' scope of practice is a key factor in managing the population health crisis; this study demonstrates that pharmacies can also advance clinical research studies by serving as sites for patient recruitment from a large, diverse, and ambulatory study population.

Mannose-binding lectin gene 2 variant DD (rs 5030737) is associated with susceptibility to COVID-19 infection in the urban population of Patna City (India)

The study aimed to measure plasma levels of Mannose-Binding Lectin (MBL) and MBL-associated serine protease-2 (MASP-2) and their polymorphisms in COVID-19 patients and controls to detect association. As MBL is a protein of immunological importance, it may contribute to the first-line host defence against SARS-CoV-2. MBL initiates the lectin pathway of complement activation with help of MASP-1 and MASP-2. Hence, appropriate serum levels of MBL and MASPs are crucial in getting protection from the disease. The polymorphisms of MBL and MASP genes affect their plasma levels, impacting their protective function and thus may manifest susceptibility, extreme variability in the clinical symptoms and progression of COVID-19 disease. The present study was conducted to find plasma levels and genetic variations in MBL and MASP-2 in COVID-19 patients and controls using PCR-RFLP and ELISA, respectively.The present study was conducted to find plasma levels and genetic variations in MBL and MASP-2 in COVID-19 patients and controls using PCR-RFLP and ELISA, respectively. Our results indicate that median serum levels of MBL and MASP-2 were significantly low in diseased cases but attained normal levels on recovery. Only genotype DD was found to be associated with COVID-19 cases in the urban population of Patna city.

A likely association between low mannan-binding lectin level and brain fog onset in long COVID patients

Brain fog can be described as a constellation of new-onset neuropsychiatric sequelae in the post-acute phase of COVID-19 (long COVID). The symptoms include inattention, short-term memory loss, and reduced mental acuity, which may undermine cognition, concentration, and sleep. This cognitive impairment, persisting for weeks or months after the acute phase of SARS-CoV-2 infection, can significantly impact on daily activities and the quality of life. An important role for the complement system (C) in the pathogenesis of COVID-19 has emerged since the beginning of pandemic outbreak. A number of pathophysiological characteristics including microangiopathy and myocarditis have been attributed to dysregulated C activation due to SARS-CoV-2 infection. Mannan-binding lectin (MBL), the first recognition subcomponent of the C lectin pathway, has been shown to bind to glycosylated SARS-CoV-2 spike protein, genetic variants of MBL2 are suggested to have an association with severe COVID-19 manifestations requiring hospitalization. In the present study, we evaluated MBL activity (lectin pathway activation) and levels in the sera of a cohort of COVID-19 patients, presenting brain fog or only hyposmia/hypogeusia as persistent symptoms, and compared them with healthy volunteers. We found significantly lower levels of MBL and lectin pathway activity in the sera of patients experiencing brain fog as compared to recovered COVID-19 patients without brain fog. Our data indicate that long COVID-associated brain fog can be listed among the variegate manifestations of increased susceptibility to infections and diseases contributed by MBL deficiency.

Association between mannose binding lectin gene polymorphisms and clinical severity of COVID-19 in children

BACKGROUND

Mannose-binding lectin (MBL) is a member of innate immunity and acts with MASP (MBL-associated serine protease) to activate the lectin pathway of the complement system. MBL gene polymorphisms are associated with susceptibility to infectious diseases. This study investigated whether MBL2 genotype, serum MBL levels, and serum MASP-2 levels affect the course of SARS-CoV-2 infection.

METHODS AND RESULTS

Pediatric patients diagnosed with COVID-19 by positive real-time polymerase chain reaction (PCR) were included in the study. Single nucleotide polymorphisms in the promoter and exon 1 in the MBL2 gene (rs11003125, rs7096206, rs1800450, rs1800451, rs5030737) were identified by a PCR and restriction fragment length polymorphisms analysis. Serum MBL and MASP-2 levels were measured by ELISA. COVID-19 patients were divided into asymptomatic and symptomatic. Variables were compared between these two groups. A total of 100 children were included in the study. The mean age of the patients was 130 ± 67.2 months. Of the patients, 68 (68%) were symptomatic, and 32 (32%) were asymptomatic. The polymorphisms in the - 221nt and - 550nt promoter regions did not differ between groups (p > 0.05). All codon 52 and codon 57 genotypes were determined as wild-type AA. AB genotypes were found 45.6% in symptomatic patients while 23.5% in asymptomatics. Moreover, BB genotype was detected 9.4% in symptomatic and 6.3% in asymptomatic patients (p < 0.001). B allele was more frequent in symptomatic patients (46.3%) compared to asymptomatic patients (10.9%). (p < 0.001). Serum MBL and MASP-2 levels did not differ statistically between the groups (p = 0.295, p = 0.073).

CONCLUSION

These findings suggest that codon 54 polymorphism in the MBL2 gene exon-1 region can be associated with the symptomatic course of COVID-19.

Complement lectin pathway activation is associated with COVID-19 disease severity, independent of MBL2 genotype subgroups

Introduction

While complement is a contributor to disease severity in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections, all three complement pathways might be activated by the virus. Lectin pathway activation occurs through different pattern recognition molecules, including mannan binding lectin (MBL), a protein shown to interact with SARS-CoV-2 proteins. However, the exact role of lectin pathway activation and its key pattern recognition molecule MBL in COVID-19 is still not fully understood.

Methods

We therefore investigated activation of the lectin pathway in two independent cohorts of SARS-CoV-2 infected patients, while also analysing MBL protein levels and potential effects of the six major single nucleotide polymorphisms (SNPs) found in the MBL2 gene on COVID-19 severity and outcome.

Results

We show that the lectin pathway is activated in acute COVID-19, indicated by the correlation between complement activation product levels of the MASP-1/C1-INH complex (p=0.0011) and C4d (p&lt;0.0001) and COVID-19 severity. Despite this, genetic variations in MBL2 are not associated with susceptibility to SARS-CoV-2 infection or disease outcomes such as mortality and the development of Long COVID.

Conclusion

In conclusion, activation of the MBL-LP only plays a minor role in COVID-19 pathogenesis, since no clinically meaningful, consistent associations with disease outcomes were noted.

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.

The COVID-19 Pandemic and Explaining Outcomes in Africa: Could Genomic Variation Add to the Debate?

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the etiological agent of COVID-19, emanated from the Wuhan Province in China and rapidly spread across the globe causing extensive morbidity and mortality rate, and affecting the global economy and livelihoods. Contrary to early predictions of "body bags" across Africa, the African COVID-19 pandemic was marked by apparent low case numbers and an overall mortality rate when compared with the other geographical regions. Factors used to describe this unexpected pattern included a younger population, a swifter and more effective national health policy, limited testing capacities, and the possibility of inadequate reporting of the cases, among others. However, despite genomics contributing to interindividual variations in many diseases across the world, there are inadequate genomic and multiomics data on COVID-19 in Africa that prevent richer transdisciplinary discussions on the contribution of genomics to the spread of COVID-19 pandemic. To invite future debates on comparative studies of COVID-19 genomics and the pandemic spread around the world regions, this expert review evaluates the reported frequency distribution of genetic variants in candidate genes that are likely to affect COVID-19 infection dynamics/disease outcomes. We propose here that genomic variation should be considered among the many factors determining the COVID-19 infection and its outcomes in African populations and across the world.

Serum peptidome profiles immune response of COVID-19 Vaccine administration

Background

Coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused significant loss of life and property. In response to the serious pandemic, recently developed vaccines against SARS-CoV-2 have been administrated to the public. Nevertheless, the research on human immunization response against COVID-19 vaccines is insufficient. Although much information associated with vaccine efficacy, safety and immunogenicity has been reported by pharmaceutical companies based on laboratory studies and clinical trials, vaccine evaluation needs to be extended further to better understand the effect of COVID-19 vaccines on human beings.

Methods

We performed a comparative peptidome analysis on serum samples from 95 participants collected at four time points before and after receiving CoronaVac. The collected serum samples were analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) to profile the serum peptides, and also subjected to humoral and cellular immune response analyses to obtain typical immunogenicity information.

Results

Significant difference in serum peptidome profiles by MALDI-TOF MS was observed after vaccination. By supervised statistical analysis, a total of 13 serum MALDI-TOF MS feature peaks were obtained on day 28 and day 42 of vaccination. The feature peaks were identified as component C1q receptor, CD59 glycoprotein, mannose-binding protein C, platelet basic protein, CD99 antigen, Leucine-rich alpha-2-glycoprotein, integral membrane protein 2B, platelet factor 4 and hemoglobin subunits. Combining with immunogenicity analysis, the study provided evidence for the humoral and cellular immune responses activated by CoronaVac. Furthermore, we found that it is possible to distinguish neutralizing antibody (NAbs)-positive from NAbs-negative individuals after complete vaccination using the serum peptidome profiles by MALDI-TOF MS together with machine learning methods, including random forest (RF), partial least squares-discriminant analysis (PLS-DA), linear support vector machine (SVM) and logistic regression (LR).

Conclusions

The study shows the promise of MALDI-TOF MS-based serum peptidome analysis for the assessment of immune responses activated by COVID-19 vaccination, and discovered a panel of serum peptides biomarkers for COVID-19 vaccination and for NAbs generation. The method developed in this study can help not only in the development of new vaccines, but also in the post-marketing evaluation of developed vaccines.

Clinical implications of host genetic variation and susceptibility to severe or critical COVID-19

Since the start of the coronavirus disease 2019 (COVID-19) pandemic, important insights have been gained into virus biology and the host factors that modulate the human immune response against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). COVID-19 displays a highly variable clinical picture that ranges from asymptomatic disease to lethal pneumonia. Apart from well-established general risk factors such as advanced age, male sex and chronic comorbidities, differences in host genetics have been shown to influence the individual predisposition to develop severe manifestations of COVID-19. These differences range from common susceptibility loci to rare genetic variants with strongly predisposing effects, or proven pathogenic variants that lead to known or novel inborn errors of immunity (IEI), which constitute a growing group of heterogeneous Mendelian disorders with increased susceptibility to infectious disease, auto-inflammation, auto-immunity, allergy or malignancies. The current genetic findings point towards a convergence of common and rare genetic variants that impact the interferon signalling pathways in patients with severe or critical COVID-19. Monogenic risk factors that impact IFN-I signalling have an expected prevalence between 1 and 5% in young, previously healthy individuals (<60 years of age) with critical COVID-19. The identification of these IEI such as X-linked TLR7 deficiency indicates a possibility for targeted genetic screening and personalized clinical management. This review aims to provide an overview of our current understanding of the host genetic factors that predispose to severe manifestations of COVID-19 and focuses on rare variants in IFN-I signalling genes and their potential clinical implications.

Ethnobotanical Uses, Phytochemistry, Toxicology, and Pharmacological Properties of Euphorbia neriifolia Linn. against Infectious Diseases: A Comprehensive Review

Medicinal plants have considerable potential as antimicrobial agents due to the presence of secondary metabolites. This comprehensive overview aims to summarize the classification, morphology, and ethnobotanical uses of Euphorbia neriifolia L. and its derived phytochemicals with the recent updates on the pharmacological properties against emerging infectious diseases, mainly focusing on bacterial, viral, fungal, and parasitic infections. The data were collected from electronic databases, including Google Scholar, PubMed, Semantic Scholar, ScienceDirect, and SpringerLink by utilizing several keywords like 'Euphorbia neriifolia', 'phytoconstituents', 'traditional uses', 'ethnopharmacological uses', 'infectious diseases', 'molecular mechanisms', 'COVID-19', 'bacterial infection', 'viral infection', etc. The results related to the antimicrobial actions of these plant extracts and their derived phytochemicals were carefully reviewed and summarized. Euphol, monohydroxy triterpene, nerifoliol, taraxerol, β-amyrin, glut-5-(10)-en-1-one, neriifolione, and cycloartenol are the leading secondary metabolites reported in phytochemical investigations. These chemicals have been shown to possess a wide spectrum of biological functions. Different extracts of E. neriifolia exerted antimicrobial activities against various pathogens to different extents. Moreover, major phytoconstituents present in this plant, such as quercetin, rutin, friedelin, taraxerol, epitaraxerol, taraxeryl acetate, 3β-friedelanol, 3β-acetoxy friedelane, 3β-simiarenol, afzelin, 24-methylene cycloarenol, ingenol triacetate, and β-amyrin, showed significant antimicrobial activities against various pathogens that are responsible for emerging infectious diseases. This plant and the phytoconstituents, such as flavonoids, monoterpenoids, diterpenoids, triterpenoids, and alkaloids, have been found to have significant antimicrobial properties. The current evidence suggests that they might be used as leads in the development of more effective drugs to treat emerging infectious diseases, including the 2019 coronavirus disease (COVID-19).

Recognition of Cell Wall Mannosylated Components as a Conserved Feature for Fungal Entrance, Adaptation and Survival Within Trophozoites of Acanthamoeba castellanii and Murine Macrophages

Acanthamoeba castellanii (Ac) is a species of free-living amoebae (FLAs) that has been widely applied as a model for the study of host-parasite interactions and characterization of environmental symbionts. The sharing of niches between Ac and potential pathogens, such as fungi, favors associations between these organisms. Through predatory behavior, Ac enhances fungal survival, dissemination, and virulence in their intracellular milieu, training these pathogens and granting subsequent success in events of infections to more evolved hosts. In recent studies, our group characterized the amoeboid mannose binding proteins (MBPs) as one of the main fungal recognition pathways. Similarly, mannose-binding lectins play a key role in activating antifungal responses by immune cells. Even in the face of similarities, the distinct impacts and degrees of affinity of fungal recognition for mannose receptors in amoeboid and animal hosts are poorly understood. In this work, we have identified high-affinity ligands for mannosylated fungal cell wall residues expressed on the surface of amoebas and macrophages and determined the relative importance of these pathways in the antifungal responses comparing both phagocytic models. Mannose-purified surface proteins (MPPs) from both phagocytes showed binding to isolated mannose/mannans and mannosylated fungal cell wall targets. Although macrophage MPPs had more intense binding when compared to the amoeba receptors, the inhibition of this pathway affects fungal internalization and survival in both phagocytes. Mass spectrometry identified several MPPs in both models, and in silico alignment showed highly conserved regions between spotted amoeboid receptors (MBP and MBP1) and immune receptors (Mrc1 and Mrc2) and potential molecular mimicry, pointing to a possible convergent evolution of pathogen recognition mechanisms.

Mannose-Binding Lectin 2 Gene Polymorphism during Pandemic: COVID-19 Family

Mannose-binding lectin 2 (MBL2) is a serine protease which is believed to be an important factor in the inherited immune system. In this article, we present a coronavirus disease 2019 (COVID-19) family of five patients: a 56-year-old father, a 51-year-old mother, two sons aged 23 and 21 years, and a 15-year-old daughter. According to the results of MBL2rs1800450 variant analysis performed, the father had homozygous mutant, the mother had homozygous normal, and the three children had heterozygous mutant genotype. When we compared the clinical parameters and genotypes, MBL2 gene polymorphism plays a very important role in COVID-19 susceptibility and severe disease. The family, which makes up our study, is the proof of this situation, and it contains important implications for host factors and COVID-19.

New Insights into the Role of the Complement System in Human Viral Diseases

The complement system (CS) is part of the human immune system, consisting of more than 30 proteins that play a vital role in the protection against various pathogens and diseases, including viral diseases. Activated via three pathways, the classical pathway (CP), the lectin pathway (LP), and the alternative pathway (AP), the complement system leads to the formation of a membrane attack complex (MAC) that disrupts the membrane of target cells, leading to cell lysis and death. Due to the increasing number of reports on its role in viral diseases, which may have implications for research on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), this review aims to highlight significant progress in understanding and defining the role of the complement system in four groups of diseases of viral etiology: (1) respiratory diseases; (2) acute liver failure (ALF); (3) disseminated intravascular coagulation (DIC); and (4) vector-borne diseases (VBDs). Some of these diseases already present a serious global health problem, while others are a matter of concern and require the collaboration of relevant national services and scientists with the World Health Organization (WHO) to avoid their spread.

Immune response to SARS-CoV-2 Variants: A focus on severity, susceptibility, and preexisting immunity

The heterogeneous phenotypes among patients with coronavirus disease 2019 (COVID-19) has drawn worldwide attention, especially those with severe symptoms without comorbid conditions. Immune responses to severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the causative virus of COVID-19, occur mainly by the innate immune response via the interferon (IFN)-mediated pathways, and the adaptive immunity via the T lymphocyte and the antibody mediated pathways. The ability of the original Wuhan SARS-CoV-2 strain, and possibly more so with new emerging variants, to antagonize IFN-mediated antiviral responses can be behind the higher early viral load, higher transmissibility, and milder symptoms compared to SARS-CoV and are part of the continued clinical evolution of COVID-19. Since it first emerged, several variants of SARS-CoV-2 have been circulating worldwide. Variants that have the potential to elude natural or vaccine-mediated immunity are variants of concern. This review focuses on the main host factors that may explain the immune responses to SARS-CoV-2 and its variants in the context of susceptibility, severity, and preexisting immunity.

Host factors: Implications in immunopathogenesis of COVID-19

Coronavirus disease 2019 (COVID-19) is a viral disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). COVID-19 is more serious in people with underlying diseases, but the cause of healthy people with progressive disease is largely unknown. Host genetic factors such as ACE2 variants, IFITM-3, HLA, TMRSS2, and furin polymorphisms appear to be one of the agents involved in the progression of the COVID-19 and outcome of the disease. This review discusses the general characteristics of SARS-CoV-2, including viral features, receptors, cell entry, clinical findings, and the main human genetic factors that may contribute to the pathogenesis of COVID-19 and get the patients' situation more complex. Further knowledge in this context may help to find a way to prevent and treat this viral pneumonia.

Functional Activity of the Complement System in Hospitalized COVID-19 Patients: A Prospective Cohort Study

Aims

Although the exact factors promoting disease progression in COVID-19 are not fully elucidated, unregulated activation of the complement system (CS) seems to play a crucial role in the pathogenesis of acute lung injury (ALI) induced by SARS-CoV-2. In particular, the lectin pathway (LP) has been implicated in previous autopsy studies. The primary purpose of our study is to investigate the role of the CS in hospitalized COVID-19 patients with varying degrees of disease severity.

Methods

In a single-center prospective observational study, 154 hospitalized patients with PCR-confirmed SARS-CoV-2 infection were included. Serum samples on admission to the COVID-19 ward were collected for analysis of CS pathway activities and concentrations of LP proteins [mannose-binding lectin (MBL) and ficolin-3 (FCN-3)] & C1 esterase inhibitor (C1IHN). The primary outcome was mechanical ventilation or in-hospital death.

Results

The patients were predominately male and had multiple comorbidities. ICU admission was required in 16% of the patients and death (3%) or mechanical ventilation occurred in 23 patients (15%). There was no significant difference in LP activity, MBL and FCN-3 concentrations according to different peak disease severities. The median alternative pathway (AP) activity was significantly lower (65%, IQR 50-94) in patients with death/invasive ventilation compared to patients without (87%, IQR 68-102, p=0.026). An optimal threshold of <65.5% for AP activity was derived from a ROC curve resulting in increased odds for death or mechanical ventilation (OR 4,93; 95% CI 1.70-14.33, p=0.003) even after adjustment for confounding factors. Classical pathway (CP) activity was slightly lower in patients with more severe disease (median 101% for death/mechanical ventilation vs 109%, p=0.014). C1INH concentration correlated positively with length of stay, inflammatory markers and disease severity on admission but not during follow-up.

Conclusion

Our results point to an overactivated AP in critically ill COVID-19 patients in vivo leading to complement consumption and consequently to a significantly reduced AP activity in vitro. The LP does not seem to play a role in the progression to severe COVID-19. Apart from its acute phase reaction the significance of C1INH in COVID-19 requires further studies.

Interindividual immunogenic variants: Susceptibility to coronavirus, respiratory syncytial virus and influenza virus

The coronavirus disease (Covid-19) pandemic is the most serious event of the year 2020, causing considerable global morbidity and mortality. The goal of this review is to provide a comprehensive summary of reported associations between inter-individual immunogenic variants and disease susceptibility or symptoms caused by the coronavirus strains severe acute respiratory syndrome-associated coronavirus, severe acute respiratory syndrome-associated coronavirus-2, and two of the main respiratory viruses, respiratory syncytial virus and influenza virus. The results suggest that the genetic background of the host could affect the levels of proinflammatory and anti-inflammatory cytokines and might modulate the progression of Covid-19 in affected patients. Notably, genetic variations in innate immune components such as toll-like receptors and mannose-binding lectin 2 play critical roles in the ability of the immune system to recognize coronavirus and initiate an early immune response to clear the virus and prevent the development of severe symptoms. This review provides promising clues related to the potential benefits of using immunotherapy and immune modulation for respiratory infectious disease treatment in a personalized manner.

Investigation of MBL2 and NOS3 functional gene variants in suspected COVID-19 PCR (-) patients

For COVID-19 (Coronavirus Disease-2019) cases, detecting host-based factors that predispose to infection is a very important research area. In this study, the aim is to investigate the MBL2 and NOS3 gene polymorphisms in COVID-19 patients with lung involvement, whose first nasopharyngeal PCR results were negative. Seventy-nine patients diagnosed with COVID-19 between April-June 2020 who were admitted to a university hospital, and 100 healthy controls were included. In the first statistical analysis performed between PCR-positive, CT-negative and PCR-negative, CT-positive patients; the AB of MBL2 genotype was significantly higher in the first group (p = 0.049). The B allele was also significantly higher in the same subgroup (p = 0.001). The absence of the AB genotype was found to increase the risk of CT positivity by 6.9 times. The AB genotype of MBL2 was higher in healthy controls (p = 0.006). The absence of the AB genotype was found to increase the risk of CT positivity; also, it can be used for early detection and isolation of patients with typical lung involvement who had enough viral loads, but whose initial PCR results were negative.

MBL deficiency-causing B allele (rs1800450) as a risk factor for severe COVID-19

The COVID-19 pandemic represents one of the greatest challenges in modern medicine. The disease is characterized by a variable clinical phenotype, ranging from asymptomatic carriage to severe and/or critical disease, which bears poor prognosis and outcome because of the development of severe acute respiratory distress syndrome (SARS) requiring ICU hospitalization, multi-organ failure and death. Therefore, the determination of risk factors predisposing to disease phenotype is of outmost importance. The aim of our study was to evaluate which predisposing factors, including MBL2 genotyping, affected clinical phenotype in 264 COVID-19 patients. We demonstrated that older age along with underlying comorbidities, primarily obesity, chronic inflammatory disorders and diabetes mellitus, represent the most important risk factors related to hospitalization, the development of pneumonia and SARS. Moreover, we found that the presence of the MBL deficiency-causing B allele (rs1800450) was significantly associated with almost 2-fold increased risk for developing pneumonia and requiring hospitalization, suggesting its usage as a molecular predictor of severe disease in SARS-CoV-2 infected individuals.

Genetic polymorphisms as multi-biomarkers in severe acute respiratory syndrome (SARS) by coronavirus infection: A systematic review of candidate gene association studies

The Severe acute respiratory syndrome may be caused by coronavirus disease which has resulted in a global pandemic. Polymorphisms in the population play a role in susceptibility to severity. We aimed to perform a systematic review related to the effect of single nucleotide polymorphisms in the development of severe acute respiratory syndrome (SARS). Twenty-eight eligible articles published were identified in PubMed, ScienceDirect, Web of Science, PMC Central and Portal BVS and additional records, with 20 studies performed in China. Information on study characteristics, genetic polymorphisms, and comorbidities was extracted. Study quality was assessed by the STrengthening the REporting of Genetic Association (STREGA) guideline. Few studies investigated the presence of polymorphisms in HLA, ACE1, OAS-1, MxA, PKR, MBL, E-CR1, FcγRIIA, MBL2, L-SIGN (CLEC4M), IFNG, CD14, ICAM3, RANTES, IL-12 RB1, TNFA, CXCL10/IP-10, CD209 (DC-SIGN), AHSG, CYP4F3 and CCL2 with the susceptibility or protection to SARS-Cov. This review provides comprehensive evidence of the association between genetic polymorphisms and susceptibility or protection to severity SARS-CoV. The literature about coronavirus infection, susceptibility to severe acute respiratory syndrome (SARS) and genetic variations is scarce. Further studies are necessary to provide more concrete evidence, mainly related to Covid-19.

The immune response to SARS-CoV-2 and COVID-19 immunopathology - Current perspectives

SARS-CoV-2 is a new beta coronavirus, similar to SARS-CoV-1, that emerged at the end of 2019 in the Hubei province of China. It is responsible for coronavirus disease 2019 (COVID-19), which was declared a pandemic by the World Health Organization on March 11, 2020. The ability to gain quick control of the pandemic has been hampered by a lack of detailed knowledge about SARS-CoV-2-host interactions, mainly in relation to viral biology and host immune response. The rapid clinical course seen in COVID-19 indicates that infection control in asymptomatic patients or patients with mild disease is probably due to the innate immune response, as, considering that SARS-CoV-2 is new to humans, an effective adaptive response would not be expected to occur until approximately 2-3 weeks after contact with the virus. Antiviral innate immunity has humoral components (complement and coagulation-fibrinolysis systems, soluble proteins that recognize glycans on cell surface, interferons, chemokines, and naturally occurring antibodies) and cellular components (natural killer cells and other innate lymphocytes). Failure of this system would pave the way for uncontrolled viral replication in the airways and the mounting of an adaptive immune response, potentially amplified by an inflammatory cascade. Severe COVID-19 appears to be due not only to viral infection but also to a dysregulated immune and inflammatory response. In this paper, the authors review the most recent publications on the immunobiology of SARS-CoV-2, virus interactions with target cells, and host immune responses, and highlight possible associations between deficient innate and acquired immune responses and disease progression and mortality. Immunotherapeutic strategies targeting both the virus and dysfunctional immune responses are also addressed.

Genome-wide association study of COVID-19 severity among the Chinese population

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection causes a broad clinical spectrum of coronavirus disease 2019 (COVID-19). The development of COVID-19 may be the result of a complex interaction between the microbial, environmental, and host genetic components. To reveal genetic determinants of susceptibility to COVID-19 severity in the Chinese population, we performed a genome-wide association study on 885 severe or critical COVID-19 patients (cases) and 546 mild or moderate patients (controls) from two hospitals, Huoshenshan and Union hospitals at Wuhan city in China. We identified two loci on chromosome 11q23.3 and 11q14.2, which are significantly associated with the COVID-19 severity in the meta-analyses of the two cohorts (index rs1712779: odds ratio [OR] = 0.49; 95% confidence interval [CI], 0.38-0.63 for T allele; P = 1.38 × 10^-8; and index rs10831496: OR = 1.66; 95% CI, 1.38-1.98 for A allele; P = 4.04 × 10^-8, respectively). The results for rs1712779 were validated in other two small COVID-19 cohorts in the Asian populations (P = 0.029 and 0.031, respectively). Furthermore, we identified significant eQTL associations for REXO2, C11orf71, NNMT, and CADM1 at 11q23.3, and CTSC at 11q14.2, respectively. In conclusion, our findings highlight two loci at 11q23.3 and 11q14.2 conferring susceptibility to the severity of COVID-19, which might provide novel insights into the pathogenesis and clinical treatment of this disease.

Genetic Risk Factors for the Development of COVID-19 Coronavirus Infection

The COVID-19 coronavirus pandemic has spread to 215 countries around the world and caused tens of millions of infections and more than a million deaths worldwide. In the midst of COVID-19 infection, it is extremely important to identify new protein and gene targets that may be highly sensitive diagnostic and prognostic markers of the severity and outcome of the disease for combating this pandemic. Identification of individual genetic predisposition allows personalizing programs of medical rehabilitation and therapy. It has now been shown that the transmissibility and severity of COVID-19 infection can be affected by gene variants in both the human body (ACE2, HLA-B*4601, FcγRIIA, MBL, TMPRSS2, TNFA, IL6, blood group A antigen, etc.) and the virus itself (ORF8 in RNA polymerase, ORF6 in RNA primase, S, N, E proteins). The presence of mutations in the proteins of the virus can change the affinity and specificity for the binding of targeted drugs to them, being the molecular basis of individual differences in the response of the human body to antiviral drugs and/or vaccines. The review summarizes the data on the variants of the genomes of the coronavirus and humans associated with an individual predisposition to an increased or decreased risk of transmission, severity, and outcome of COVID-19 infection. Targeted drugs and vaccines being developed for the therapy of COVID-19 infection are briefly reviewed.

An immunogenetic view of COVID-19

Meeting the challenges brought by the COVID-19 pandemic requires an interdisciplinary approach. In this context, integrating knowledge of immune function with an understanding of how genetic variation influences the nature of immunity is a key challenge. Immunogenetics can help explain the heterogeneity of susceptibility and protection to the viral infection and disease progression. Here, we review the knowledge developed so far, discussing fundamental genes for triggering the innate and adaptive immune responses associated with a viral infection, especially with the SARS-CoV-2 mechanisms. We emphasize the role of the HLA and KIR genes, discussing what has been uncovered about their role in COVID-19 and addressing methodological challenges of studying these genes. Finally, we comment on questions that arise when studying admixed populations, highlighting the case of Brazil. We argue that the interplay between immunology and an understanding of genetic associations can provide an important contribution to our knowledge of COVID-19.

Neuropathophysiology of coronavirus disease 2019: neuroinflammation and blood brain barrier disruption are critical pathophysiological processes that contribute to the clinical symptoms of SARS-CoV-2 infection

Coronavirus disease 2019 (COVID-19) is caused by the novel SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) first discovered in Wuhan, Hubei province, China in December 2019. SARS-CoV-2 has infected several millions of people, resulting in a huge socioeconomic cost and over 2.5 million deaths worldwide. Though the pathogenesis of COVID-19 is not fully understood, data have consistently shown that SARS-CoV-2 mainly affects the respiratory and gastrointestinal tracts. Nevertheless, accumulating evidence has implicated the central nervous system in the pathogenesis of SARS-CoV-2 infection. Unfortunately, however, the mechanisms of SARS-CoV-2 induced impairment of the central nervous system are not completely known. Here, we review the literature on possible neuropathogenic mechanisms of SARS-CoV-2 induced cerebral damage. The results suggest that downregulation of angiotensin converting enzyme 2 (ACE2) with increased activity of the transmembrane protease serine 2 (TMPRSS2) and cathepsin L in SARS-CoV-2 neuroinvasion may result in upregulation of proinflammatory mediators and reactive species that trigger neuroinflammatory response and blood brain barrier disruption. Furthermore, dysregulation of hormone and neurotransmitter signalling may constitute a fundamental mechanism involved in the neuropathogenic sequelae of SARS-CoV-2 infection. The viral RNA or antigenic peptides also activate or interact with molecular signalling pathways mediated by pattern recognition receptors (e.g., toll-like receptors), nuclear factor kappa B, Janus kinase/signal transducer and activator of transcription, complement cascades, and cell suicide molecules. Potential molecular targets and therapeutics of SARS-CoV-2 induced neurologic damage are also discussed.

Status of mannose-binding lectin (MBL) and complement system in COVID-19 patients and therapeutic applications of antiviral plant MBLs

Coronavirus disease 2019 (COVID-19) is an infectious disease caused by a virus called "Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2)." In the majority of patients, infection with COVID-19 may be asymptomatic or may cause only mild symptoms. However, in some patients, there can also be immunological problems, such as macrophage activation syndrome (CSS) that results in cytokine storm syndrome (CSS) and acute respiratory distress syndrome (ARDS). Comprehension of host-microbe communications is the critical aspect in the advancement of new therapeutics against infectious illnesses. Endogenous animal lectins, a class of proteins, may perceive non-self glycans found on microorganisms. Serum mannose-binding lectin (sMBL), as a part of the innate immune framework, recognizes a wide range of microbial microorganisms and activates complement cascade via an antibody-independent pathway. Although the molecular basis for the intensity of SARS-CoV-2 infection is not generally understood, scientific literature indicates that COVID-19 is correlated with unregulated activation of the complement in terms of disease severity. Disseminated intravascular coagulation (DIC), inflammation, and immune paralysis contribute to unregulated complement activation. Pre-existing genetic defects in MBL and their association with complement play a major role in immune response dysregulation caused by SARS-CoV-2. In order to generate anti-complement-based therapies in Covid-19, an understanding of sMBL in immune response to SARS-CoV-2 and complement is therefore essential. This review highlights the role of endogenous sMBL and complement activation during SARS-CoV-2 infection and their therapeutic management by various agents, mainly plant lectins, since antiviral mannose-binding plant lectins (pMBLs) offer potential applications in the prevention and control of viral infections.

Coronavirus: Pure Infectious Disease or Genetic Predisposition

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which causes novel coronavirus disease (COVID-19), is the seventh pathogenic coronavirus recently discovered in December 2019 in Wuhan, China. To date, our knowledge about its effect on the human host remains limited. It is well known that host genetic factors account for the individual differences in the susceptibility to infectious diseases. The genetic susceptibility factors to COVID-19 and its severity are associated with several unanswered questions. However, the experience gained from an earlier strain of coronavirus, SARS-CoV-1, which shows 78% genetic similarity to SARS-CoV-2 and uses the same receptor to bind to host cells, could provide some clues. It, therefore, seems possible to assemble new evidence in order to solve a potential genetic predisposition puzzle for COVID-19. In this chapter, the puzzle pieces, including virus entry receptors, immune response, and inflammation-related genes, as well as the probable genetic predisposition models to COVID-19, are discussed.

Mannose-binding lectin and risk of infections in type 2 diabetes: A Danish cohort study

AIMS

In individuals at increased risk of infections, e.g., patients with type 2 diabetes, low MBL may have detrimental effects. We used the Mendelian randomization principle to examine whether genetically low MBL is a risk factor for developing infections in patients with type 2 diabetes.

METHODS

Serum MBL (n = 7305) and MBL genotype (n = 3043) were determined in a nationwide cohort of patients with new type 2 diabetes and up to 8 years follow-up for hospital-treated infections and community-based antimicrobial prescriptions. The associations were examined in spline and Cox regression analyses.

RESULTS

1140 patients (16%) were hospitalized with an infection and 5077 patients (70%) redeemed an antimicrobial prescription. For low (≤100 μg/L) versus intermediate (101-1000 μg/L) serum MBL concentration, the adjusted hazard ratios (aHRs) were 1.13(95% confidence interval, 0.96-1.33) for any hospital-treated infections and 1.19(1.01-1.41) for bacterial infections. Low MBL expression genotype was not associated with risk of any hospital-treated infections except for diarrheal diseases (aHR 2.23[1.04-4.80]). Low MBL expression genotype, but not low serum MBL, was associated with increased risk for antimicrobial prescriptions (aHR 1.18[1.04-2.34] and antibacterial prescriptions 1.20[1.05-1.36]).

CONCLUSIONS

Low MBL is a weak causal risk factor for developing infections in patients with type 2 diabetes.

Why does SARS-CoV-2 hit in different ways? Host genetic factors can influence the acquisition or the course of COVID-19

The identification of high-risk factors for the infection by SARS-CoV-2 and the negative outcome of COVID-19 is crucial. The genetic background of the host might account for individual responses to SARS-CoV-2 infection besides age and comorbidities. A list of candidate polymorphisms is needed to drive targeted screens, given the existence of frequent polymorphisms in the general population. We carried out text mining in the scientific literature to draw up a list of genes referable to the term "SARS-CoV*". We looked for frequent mutations that are likely to affect protein function in these genes. Ten genes, mostly involved in innate immunity, and thirteen common variants were identified, for some of these the involvement in COVID-19 is supported by publicly available epidemiological data. We looked for available data on the population distribution of these variants and we demonstrated that the prevalence of five of them, Arg52Cys (rs5030737), Gly54Asp (rs1800450) and Gly57Glu (rs1800451) in MBL2, Ala59Thr (rs25680) in CD27, and Val197Met (rs12329760) in TMPRSS2, correlates with the number of cases and/or deaths of COVID-19 observed in different countries. The association of the TMPRSS2 variant provides epidemiological evidence of the usefulness of transmembrane protease serine 2 inhibitors for the cure of COVID-19. The identified genetic variants represent a basis for the design of a cost-effective assay for population screening of genetic risk factors in the COVID-19 pandemic.

The central role of the nasal microenvironment in the transmission, modulation, and clinical progression of SARS-CoV-2 infection

The novel coronavirus SARS-CoV-2 enters into the human body mainly through the ACE2 + TMPRSS2+ nasal epithelial cells. The initial host response to this pathogen occurs in a peculiar immune microenvironment that, starting from the Nasopharynx-Associated Lymphoid Tissue (NALT) system, is the product of a long evolutionary process that is aimed to first recognize exogenous airborne agents. In the present work, we want to critically review the latest molecular and cellular findings on the mucosal response to SARS-CoV-2 in the nasal cavity and in NALT, and to analyze its impact in the subsequent course of COVID-19. Finally, we want to explore the possibility that the regulation of the systemic inflammatory network against the virus can be modulated starting from the initial phases of the nasal and nasopharyngeal response and this may have several clinical and epidemiological implications starting from a mucosal vaccine development.

Mannose binding lectin gene 2 (rs1800450) missense variant may contribute to development and severity of COVID-19 infection

Background/objectives

COVID-19 followed a mortal course in some young patients without any underlying factors, however, it followed a very benign course in some very older individuals with multiple comorbidities. These observations question if some genetic factors may be related to the vulnerability and poor prognosis of the disease. In this study, we aimed to investigate whether MBL2 gene B variant at codon 54 (rs1800450) were related to the variabilities in clinical course of this infection.

Methods

284 PCR-confirmed COVID-19 patients and 100 healthy controls were included in the study. COVID-19 patients were subdivided according to the clinical features and clinical characteristics were analyzed. DNAs of all patients and controls were examined for the codon 54 A/B (gly54asp: rs1800450) variation in exon 1 of the MBL2 gene.

Results

In univariate analysis, BB genotype of MBL2 gene was more common among COVID-19 cases compared with controls (10.9% vs 1.0%, respectively; OR = 12.1, 95%CI = 1.6–90.1, p = 0.001). Multivariate analyses, adjusted for age, sex and MBL genetic variants, revealed that when compared with the COVID-19 patients that had AA genotype (reference), the patients that had BB or AB genotypes suffered from a higher risk for severe disease (for BB genotype, odds ratio (OR) = 5.3, p < 0.001; for AB genotype, OR = 2.9, p = 0.001) and for ICU need (for BB genotype, OR = 19.6, p < 0.001; for AB genotype, OR = 6.9, p = 0.001). On the other hand, there was not any significant difference between the genotype variants in terms of mortality at 28 days or development of secondary bacterial infection.

Conclusion

The B variants of MBL2 gene at codon 54, which were associated with lower MBL2 levels, were related to a higher risk for a more severe clinical course of COVID-19 infection in some respects. Our findings may have potential future implications, e.g. for use of MBL protein as potential therapeutics or prioritize the individuals with B variants during vaccination strategies.

How glycobiology can help us treat and beat the COVID-19 pandemic

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged during the last months of 2019, spreading throughout the world as a highly transmissible infectious illness designated as COVID-19. Vaccines have now appeared, but the challenges in producing sufficient material and distributing them around the world means that effective treatments to limit infection and improve recovery are still urgently needed. This review focuses on the relevance of different glycobiological molecules that could potentially serve as or inspire therapeutic tools during SARS-CoV-2 infection. As such, we highlight the glycobiology of the SARS-CoV-2 infection process, where glycans on viral proteins and on host glycosaminoglycans have critical roles in efficient infection. We also take notice of the glycan-binding proteins involved in the infective capacity of virus and in human defense. In addition, we critically evaluate the glycobiological contribution of candidate drugs for COVID-19 therapy such as glycans for vaccines, anti-glycan antibodies, recombinant lectins, lectin inhibitors, glycosidase inhibitors, polysaccharides, and numerous glycosides, emphasizing some opportunities to repurpose FDA-approved drugs. For the next-generation drugs suggested here, biotechnological engineering of new probes to block the SARS-CoV-2 infection might be based on the essential glycobiological insight on glycosyltransferases, glycans, glycan-binding proteins, and glycosidases related to this pathology.

Threading the Pieces Together: Integrative Perspective on SARS-CoV-2

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has challenged the research community globally to innovate, interact, and integrate findings across hierarchies. Research on SARS-CoV-2 has produced an abundance of data spanning multiple parallels, including clinical data, SARS-CoV-2 genome architecture, host response captured through transcriptome and genetic variants, microbial co-infections (metagenome), and comorbidities. Disease phenotypes in the case of COVID-19 present an intriguing complexity that includes a broad range of symptomatic to asymptomatic individuals, further compounded by a vast heterogeneity within the spectrum of clinical symptoms displayed by the symptomatic individuals. The clinical outcome is further modulated by the presence of comorbid conditions at the point of infection. The COVID-19 pandemic has produced an expansive wealth of literature touching many aspects of SARS-CoV-2 ranging from causal to outcome, predisposition to protective (possible), co-infection to comorbidity, and differential mortality globally. As challenges provide opportunities, the current pandemic's challenge has underscored the need and opportunity to work for an integrative approach that may be able to thread together the multiple variables. Through this review, we have made an effort towards bringing together information spanning across different domains to facilitate researchers globally in pursuit of their response to SARS-CoV-2.

Immunological basis of virus-host interaction in COVID-19

COVID-19 is a complex new viral disease, in which a strict balance between anti-viral immune response and the ensuing organ inflammation has a critical role in determining the clinical course. In adults, compelling evidence exists indicating that an uncontrolled inflammatory response ("cytokine storm") is pivotal in determining disease progression and mortality. Children may rarely present with severe disease. Modulating factors related to the host's genetic factors, age-related susceptibility, and the capability to mount appropriate immune responses might play a role in control virus load at an early stage and regulating the inflammatory reaction. Elucidating these mechanisms seems crucial in developing target therapies according to patient's age, immunologic status, and disease evolution in COVID-19.

Targeting complement cascade: an alternative strategy for COVID-19

The complement system is a stakeholder of the innate and adaptive immune system and has evolved as a crucial player of defense with multifaceted biological effects. Activation of three complement pathways leads to consecutive enzyme reactions resulting in complement components (C3 and C5), activation of mast cells and neutrophils by anaphylatoxins (C3a and C5a), the formation of membrane attack complex (MAC) and end up with opsonization. However, the dysregulation of complement cascade leads to unsolicited cytokine storm, inflammation, deterioration of alveolar lining cells, culminating in acquired respiratory destructive syndrome (ARDS). Similar pathogenesis is observed with the middle east respiratory syndrome (MERS), severe acquired respiratory syndrome (SARS), and SARS-CoV-2. Activation of the lectin pathway via mannose-binding lectin associated serine protease 2 (MASP2) is witnessed under discrete viral infections including COVID-19. Consequently, the spontaneous activation and deposits of complement components were traced in animal models and autopsy of COVID-19 patients. Pre-clinical and clinical studies evidence that the inhibition of complement components results in reduced complement deposits on target and non-target tissues, and aid in recovery from the pathological conditions of ARDS. Complement inhibitors (monoclonal antibody, protein, peptide, small molecules, etc.) exhibit great promise in blocking the activity of complement components and its downstream effects under various pathological conditions including SARS-CoV. Therefore, we hypothesize that targeting the potential complement inhibitors and complement cascade to counteract lung inflammation would be a better strategy to treat COVID-19.

The role of host genetics in susceptibility to severe viral infections in humans and insights into host genetics of severe COVID-19: A systematic review

BACKGROUND

Susceptibility to severe viral infections was reported to be associated with genetic variants in immune response genes using case reports and GWAS studies. SARS-CoV-2 is an emergent viral disease that caused millions of COVID-19 cases all over the world. Around 15 % of cases are severe and some of them are accompanied by dysregulated immune system and cytokine storm. There is increasing evidence that severe manifestations of COVID-19 might be attributed to human genetic variants in genes related to immune deficiency and or inflammasome activation (cytokine storm).

OBJECTIVE

Identify the candidate genes that are likely to aid in explaining severe COVID-19 and provide insights to understand the pathogenesis of severe COVID-19.

METHODS

In this article, we systematically reviewed genes related to viral susceptibility that were reported in human genetic studies (Case-reports and GWAS) to understand the role of host viral interactions and to provide insights into the pathogenesis of severe COVID-19.

RESULTS

We found 40 genes associated with viral susceptibility and 21 of them were associated with severe SARS-CoV disease and severe COVID-19. Some of those genes were implicated in TLR pathways, others in C-lectin pathways, and others were related to inflammasome activation (cytokine storm).

CONCLUSION

This compilation represents a list of candidate genes that are likely to aid in explaining severe COVID-19 which are worthy of inclusion in gene panels and during meta-analysis of different variants in host genetics studies of COVID-19. In addition, we provide several hypotheses for severe COVID-19 and possible therapeutic targets.

Innate Immunity and Influenza A Virus Pathogenesis: Lessons for COVID-19

There is abundant evidence that the innate immune response to influenza A virus (IAV) is highly complex and plays a key role in protection against IAV induced infection and illness. Unfortunately it also clear that aspects of innate immunity can lead to severe morbidity or mortality from IAV, including inflammatory lung injury, bacterial superinfection, and exacerbation of reactive airways disease. We review broadly the virus and host factors that result in adverse outcomes from IAV and show evidence that inflammatory responses can become damaging even apart from changes in viral replication per se, with special focus on the positive and adverse effects of neutrophils and monocytes. We then evaluate in detail the role of soluble innate inhibitors including surfactant protein D and antimicrobial peptides that have a potential dual capacity for down-regulating viral replication and also inhibiting excessive inflammatory responses and how these innate host factors could possibly be harnessed to treat IAV infection. Where appropriate we draw comparisons and contrasts the SARS-CoV viruses and IAV in an effort to point out where the extensive knowledge existing regarding severe IAV infection could help guide research into severe COVID 19 illness or vice versa.

The Influence of the Lectin Pathway of Complement Activation on Infections of the Respiratory System

Lung diseases are among the leading causes of morbidity and mortality. Complement activation may prevent a variety of respiratory infections, but on the other hand, could exacerbate tissue damage or contribute to adverse side effects. In this review, the associations of factors specific for complement activation via the lectin pathway (LP) with infections of the respiratory system, from birth to adulthood, are discussed. The most extensive data concern mannose-binding lectin (MBL) which together with other collectins (collectin-10, collectin-11) and the ficolins (ficolin-1, ficolin-2, ficolin-3) belong to pattern-recognition molecules (PRM) specific for the LP. Those PRM form complexes with MBL-associated serine proteases (MASP-1, MASP-2, MASP-3) and related non-enzymatic factors (MAp19, MAp44). Beside diseases affecting humanity for centuries like tuberculosis or neonatal pneumonia, some recently published data concerning COVID-19 are summarized.

Exploring Host Genetic Polymorphisms Involved in SARS-CoV Infection Outcomes: Implications for Personalized Medicine in COVID-19

Objective

To systematically explore genetic polymorphisms associated with the clinical outcomes in SARS-CoV infection in humans.

Methods

This comprehensive literature search comprised available English papers published in PubMed/Medline and SCOPUS databases following the PRISMA-P guidelines and PICO/AXIS criteria.

Results

Twenty-nine polymorphisms located in 21 genes were identified as associated with SARS-CoV susceptibility/resistance, disease severity, and clinical outcomes predominantly in Asian populations. Thus, genes implicated in key pathophysiological processes such as the mechanisms related to the entry of the virus into the cell and the antiviral immune/inflammatory responses were identified.

Conclusions

Although caution must be taken, the results of this systematic review suggest that multiple genetic polymorphisms are associated with SARS-CoV infection features by affecting virus pathogenesis and host immune response, which could have important applications for the study and understanding of genetics in SARS-CoV-2/COVID-19 and for personalized translational clinical practice depending on the population studied and associated environments.

Coronaviruses and Nature's Pharmacy for the Relief of Coronavirus Disease 2019

Current challenges to the treatment of coronavirus disease 2019 should open new prospects in the search for novel drugs from medicinal plants and other natural products. This paper provides details of natural agents that inhibit human coronavirus entry into cells, general replication, and specific chymotrypsin-like protease (3CL^pro)-mediated replication. Medicinal plants, fungi, and marine organisms as remedies for human coronaviruses in China, Lebanon, Malaysia, Singapore, and South Africa are described. Common species include Alnus japonica (Thunb.) Steud., Artemisia annua L., Artemisia apiacea Hance, Astragalus membranaceus (Fisch.) Bunge, Cinnamomum cassia (L.) J.Presl, edible brown algae Ecklonia cava Kjellman, Euphorbia neriifolia L., Glycyrrhiza glabra L., Lonicera japonica Thunb., Pelargonium sidoides DC., Polygonum cuspidatum Siebold & Zucc., Sanguisorba officinalis L., Scutellaria baicalensis Georgi, Toona sinensis (Juss.) M.Roem., and Torreya nucifera (L.) Siebold & Zucc. At least fifty natural compounds, including alkaloids, flavonoids, glycosides, anthraquinones, lignins, and tannins, which inhibit various strains of human coronaviruses, are presented. Given the scarcity of efficacious and safe vaccines or drugs for coronavirus disease 2019, natural products are low-hanging fruits that should be harnessed as the new global frontier against severe acute respiratory syndrome coronavirus 2.

SARS-CoV-2 and COVID-19: A genetic, epidemiological, and evolutionary perspective

In less than five months, COVID-19 has spread from a small focus in Wuhan, China, to more than 5 million people in almost every country in the world, dominating the concern of most governments and public health systems. The social and political distresses caused by this epidemic will certainly impact our world for a long time to come. Here, we synthesize lessons from a range of scientific perspectives rooted in epidemiology, virology, genetics, ecology and evolutionary biology so as to provide perspective on how this pandemic started, how it is developing, and how best we can stop it.

Coronavirus disease 2019 (COVID-19) and obesity. Impact of obesity and its main comorbidities in the evolution of the disease

The COVID-19 pandemic is posing a great challenge worldwide. Its rapid progression has caused thousands of deaths worldwide. Although multiple aspects remain to be clarified, some risk factors associated with a worse prognosis have been identified. These include obesity and some of its main complications, such as diabetes and high blood pressure. Furthermore, although the possible long-term complications and psychological effects that may appear in survivors of COVID-19 are not well known yet, there is a concern that those complications may be greater in obese patients. In this manuscript, we review some of the data published so far and the main points that remain to be elucidated are emphasized.

Genetic variants of the human host influencing the coronavirus-associated phenotypes (SARS, MERS and COVID-19): rapid systematic review and field synopsis

The COVID-19 pandemic has strengthened the interest in the biological mechanisms underlying the complex interplay between infectious agents and the human host. The spectrum of phenotypes associated with the SARS-CoV-2 infection, ranging from the absence of symptoms to severe systemic complications, raised the question as to what extent the variable response to coronaviruses (CoVs) is influenced by the variability of the hosts' genetic background.To explore the current knowledge about this question, we designed a systematic review encompassing the scientific literature published from Jan. 2003 to June 2020, to include studies on the contemporary outbreaks caused by SARS-CoV-1, MERS-CoV and SARS-CoV-2 (namely SARS, MERS and COVID-19 diseases). Studies were eligible if human genetic variants were tested as predictors of clinical phenotypes.An ad hoc protocol for the rapid review process was designed according to the PRISMA paradigm and registered at the PROSPERO database (ID: CRD42020180860). The systematic workflow provided 32 articles eligible for data abstraction (28 on SARS, 1 on MERS, 3 on COVID-19) reporting data on 26 discovery cohorts. Most studies considered the definite clinical diagnosis as the primary outcome, variably coupled with other outcomes (severity was the most frequently analysed). Ten studies analysed HLA haplotypes (1 in patients with COVID-19) and did not provide consistent signals of association with disease-associated phenotypes. Out of 22 eligible articles that investigated candidate genes (2 as associated with COVID-19), the top-ranked genes in the number of studies were ACE2, CLEC4M (L-SIGN), MBL, MxA (n = 3), ACE, CD209, FCER2, OAS-1, TLR4, TNF-α (n = 2). Only variants in MBL and MxA were found as possibly implicated in CoV-associated phenotypes in at least two studies. The number of studies for each predictor was insufficient to conduct meta-analyses.Studies collecting large cohorts from different ancestries are needed to further elucidate the role of host genetic variants in determining the response to CoVs infection. Rigorous design and robust statistical methods are warranted.

Rationale for targeting complement in COVID-19

A novel coronavirus, SARS-CoV-2, has recently emerged in China and spread internationally, posing a health emergency to the global community. COVID-19 caused by SARS-CoV-2 is associated with an acute respiratory illness that varies from mild to the life-threatening acute respiratory distress syndrome (ARDS). The complement system is part of the innate immune arsenal against pathogens, in which many viruses can evade or employ to mediate cell entry. The immunopathology and acute lung injury orchestrated through the influx of pro-inflammatory macrophages and neutrophils can be directly activated by complement components to prime an overzealous cytokine storm. The manifestations of severe COVID-19 such as the ARDS, sepsis and multiorgan failure have an established relationship with activation of the complement cascade. We have collected evidence from all the current studies we are aware of on SARS-CoV-2 immunopathogenesis and the preceding literature on SARS-CoV-1 and MERS-CoV infection linking severe COVID-19 disease directly with dysfunction of the complement pathways. This information lends support for a therapeutic anti-inflammatory strategy against complement, where a number of clinically ready potential therapeutic agents are available.

Racial and Gender-Based Differences in COVID-19

The novel coronavirus disease (COVID-19) has become a global health crisis since its first appearance in Wuhan, China. Current epidemiological studies suggest that COVID-19 affects older patients with multiple comorbidities, such as hypertension, obesity, and chronic lung diseases. The differences in the incidence and severity of COVID-19 are likely to be multifaceted, depending on various biological, social, and economical factors. Specifically, the socioeconomic differences and psychological impact of COVID-19 affecting males and females are essential in pandemic mitigation and preparedness. Previous clinical studies have shown that females are less susceptible to acquire viral infections and reduced cytokine production. Female patients have a higher macrophage and neutrophil activity as well as antibody production and response. Furthermore, in-vivo studies of the angiotensin-converting enzyme 2 (ACE2) showed higher expression in the kidneys of male than female patients, which may explain the differences in susceptibility and progression of COVID-19 between male and female patients. However, it remains unknown whether the expression of ACE2 differs in the lungs of male or female patients. Disparities in healthcare access and socioeconomic status between ethnic groups may influence COVID-19 rates. Ethnic groups often have higher levels of medical comorbidities and lower socioeconomic status, which may increase their risk of contracting COVID-19 through weak cell-mediated immunity. In this article, we examine the current literature on the gender and racial differences among COVID-19 patients and further examine the possible biological mechanisms underlying these differences.