A review on the immune responses against novel emerging coronavirus (SARS-CoV-2)

Association study between killer immunoglobulin-like receptor polymorphisms and susceptibility to COVID-19 disease: a systematic review and meta-analysis

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a known virus that leads to a respiratory disease called coronavirus disease 19 (COVID-19). Natural killer (NK) cells, as members of innate immunity, possess crucial roles in restricting viral infections, including COVID-19. Their functions and development depend on receiving signals through various receptors, of which killer cell immunoglobulin-like receptors (KIRs) belong to the most effective ones. Different studies investigated the association between KIR gene content and susceptibility to COVID-19. Since previous studies have yielded contradictory results, we designed this meta-analysis study to draw comprehensive conclusions about COVID-19 risk and KIR gene association. According to PRISMA guidelines, a systematic search was performed in the electronic databases to find all studies investigating KIR gene contents in COVID-19 patients before March 2023. Any association between KIR genes and COVID-19 risk was determined by calculating pooled odds ratio (OR) and 95% confidence interval (CI). After applying the inclusion and exclusion criteria, 1673 COVID-19 patients and 1526 healthy controls from eight studies were included in this meta-analysis. As the main results, we observed a positive association between the 2DL3 (OR = 1.48, 95% CI = 1.17-1.88, P < 0.001) and susceptibility to COVID-19 and a negative association between the 2DP1 and the risk for COVID-19 (OR = 0.48, 95% CI = 0.23-0.99, P = 0.049). This meta-analysis demonstrated that KIR2DL3, as a member of iKIRs, might be associated with an increased risk of COVID-19 disease.

Epidemiological survey of elderly patients diagnosed with COVID-19 at mobile field hospitals

BACKGROUND

During the COVID-19 pandemic, the mobile field hospital, a rapidly deployable healthcare facility for emergency care, was effective in ensuring rapid diagnosis and treatment of patients with mild or asymptomatic SARS-CoV2 infections, effectively preventing the spread of COVID-19.

OBJECTIVE

We conducted a survey to gain a thorough understanding of the epidemiological traits among the elderly who contracted the Omicron variant of the SARS-CoV-2 virus at a mobile field hospital set up at the National Exhibition and Convention Center (Shanghai).

METHODS

A cross-sectional study approach was employed to examine various factors such as demographic characteristics, clinical features, vaccination status, and nucleic acid testing. We utilized the DezhenTech Integrated Electronic Medical Record Platform (Municipal Isolation Hospital) to collect data and focused on elderly individuals infected with COVID-19 in the fifth isolation zone of the mobile field hospital set up at the National Exhibition and Convention Center (Shanghai). The patients were categorized into different age groups for analysis.

RESULTS

Among the 3,183 elderly patients, 54.7% were males and 45.3% were females, with an average age of 65.32 ± 4.41 years. Among them, 47.8% (1523/3183) were 60-64 years old, 34.0% (1082/3183) were 65-69 years old, 14.0% (444/3183) were 70-74 years old, 3.2% (103/3183) were 75-79 years old, and 1.0% (31/3183) were ⩾ 80 years old. The majority (95.7%) of the elderly patients with chronic conditions had hypertension, diabetes, and coronary heart disease. The first viral nucleic acid screening showed a higher positive rate in the community and hospital fever clinics. The cumulative positive rate of the nucleic acid test in the mobile field hospital was 38.7%. The average CT value of the COVID-19 ORF1ab gene was 34.56 ± 5.98, while the average CT value of the N gene was 33.10 ± 6.50. The patients took an average of 3.40 ± 0.45 days to test negative, with a positive rate of 15.4% and an average hospital stay of 7.45 ± 0.53 days. The overall rate of COVID-19 vaccine coverage was 68.0%, with an enhanced coverage rate of 40% and a non-coverage rate of 29.3%.

CONCLUSIONS

The overall prognosis for elderly patients who experienced a mild or asymptomatic SARS-CoV-2 Omicron infection at the mobile field hospital was favorable, although the vaccination rate in general was not high. By effectively managing underlying health conditions, the duration of their hospital stay in the mobile field hospital was reduced.

Assessing the gene expression of the adenosine 5'-monophosphate-activated protein kinase (AMPK) and its relation with the IL-6 and IL-10 plasma levels in COVID-19 patients

BACKGROUND

Metabolic dysregulation and excessive inflammation are implicated in the pathogenesis of the highly infectious disease of coronavirus disease 2019 (COVID-19), which is caused by a newly emerging coronavirus (i.e., severe acute respiratory syndrome-coronavirus 2; SARS-CoV-2). The adenosine 5'-monophosphate-activated protein kinase (AMPK), an energy sensor regulating the metabolic pathways in diverse cells, exerts a regulatory role in the immune system. This study aims to examine the mRNA expression level of AMPK and the plasma levels of interleukin-6 (IL-6) and IL-10 cytokines in patients with different grades of COVID-19.

METHODS

Peripheral blood was collected from 60 patients with COVID-19 (Moderate, severe, and critical). The plasma levels of IL-6 and IL-10 were quantified by enzyme-linked immunosorbent assay (ELISA), and the mRNA expression level of AMPK was determined using real-time PCR.

RESULTS

The results showed that the plasma levels of IL-6 increased significantly in critical and severe patients compared to moderate cases of COVID-19 (P < 0.001). Moreover, IL-10 plasma concentrations were significantly higher in critical and severe cases than in moderate cases of COVID-19 (P < 0.01 and P < 0.05, respectively). Also, the gene expression of AMPK was meaningfully enhanced in critical patients relative to moderate and severe cases of COVID-19, in order (P < 0.001 and P < 0.01, respectively). There was a positive association between AMPK gene expression and plasma levels of IL-6 and IL-10 (P = 0.006, r = 0.348, P = 0.028, r = 0.283, respectively).

CONCLUSION

Increasing AMPK gene expression is likely a necessary effort of the immune system to inhibit inflammation in critical COVID-19. However, this effort seems to be inadequate, probably due to factors that induce inflammation, like erythrocyte sedimentation rate (ESR) and IL-6.

Catalase Activity of IgGs of Patients Infected with SARS-CoV-2

Coronavirus disease (COVID-19), caused by the SARS-CoV-2 coronavirus, leads to various manifestations of the post-COVID syndrome, including diabetes, heart and kidney disease, thrombosis, neurological and autoimmune diseases and, therefore, remains, so far, a significant public health problem. In addition, SARS-CoV-2 infection can lead to the hyperproduction of reactive oxygen species (ROS), causing adverse effects on oxygen transfer efficiency, iron homeostasis, and erythrocytes deformation, contributing to thrombus formation. In this work, the relative catalase activity of the serum IgGs of patients recovered from COVID-19, healthy volunteers vaccinated with Sputnik V, vaccinated with Sputnik V after recovering from COVID-19, and conditionally healthy donors were analyzed for the first time. Previous reports show that along with canonical antioxidant enzymes, the antibodies of mammals with superoxide dismutase, peroxidase, and catalase activities are involved in controlling reactive oxygen species levels. We here show that the IgGs from patients who recovered from COVID-19 had the highest catalase activity, and this was statistically significantly higher each compared to the healthy donors (1.9-fold), healthy volunteers vaccinated with Sputnik V (1.4-fold), and patients vaccinated after recovering from COVID-19 (2.1-fold). These data indicate that COVID-19 infection may stimulate the production of antibodies that degrade hydrogen peroxide, which is harmful at elevated concentrations.

Localized delivery of nanomedicine and antibodies for combating COVID-19

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has been a major health burden in the world. So far, many strategies have been investigated to control the spread of COVID-19, including social distancing, disinfection protocols, vaccines, and antiviral treatments. Despite the significant achievement, due to the constantly emerging new variants, COVID-19 is still a great challenge to the global healthcare system. It is an urgent demand for the development of new therapeutics and technologies for containing the wild spread of SARS-CoV-2. Inhaled administration is useful for the treatment of lung and respiratory diseases, and enables the drugs to reach the site of action directly with benefits of decreased dose, improved safety, and enhanced patient compliance. Nanotechnology has been extensively applied in the prevention and treatment of COVID-19. In this review, the inhaled nanomedicines and antibodies, as well as intranasal nanodrugs, for the prevention and treatment of COVID-19 are summarized.

The influence of COVID-19 infection-associated immune response on the female reproductive system†

Coronavirus disease 2019 (COVID-19) is a multi-system disease that has led to a pandemic with unprecedented ramifications. The pandemic has challenged scientists for the past 2 years and brought back previously abandoned research topics. COVID-19 infection causes a myriad of symptoms ranging from mild flu-like symptoms to severe illness requiring hospitalization. Case reports showed multiple systemic effects of COVID-19 infection, including acute respiratory distress syndrome, fibrosis, colitis, thyroiditis, demyelinating syndromes, and mania, indicating that COVID-19 can affect most human body systems. Unsurprisingly, a major concern for women all over the globe is whether a COVID-19 infection has any long-term effects on their menstrual cycle, fertility, or pregnancy. Published data have suggested an effect on the reproductive health, and we hypothesize that the reported reproductive adverse effects are due to the robust immune reaction against COVID-19 and the associated cytokine storm. While the COVID-19 receptor (angiotensin converting enzyme, ACE2) is expressed in the ovaries, uterus, vagina, and placenta, we hypothesize that it plays a less important role in the adverse effects on the reproductive system. Cytokines and glucocorticoids act on the hypothalamo-pituitary gonadal axis, arachidonic acid pathways, and the uterus, which leads to menstrual disturbances and pregnancy-related adverse events such as preterm labor and miscarriages. This hypothesis is further supported by the apparent lack of long-term effects on the reproductive health in females, indicating that when the cytokine storm and its effects are dampened, the reproductive health of women is no longer affected.

Age and Cytokine Gene Variants Modulate the Immunogenicity and Protective Effect of SARS-CoV-2 mRNA-Based Vaccination

The introduction of anti-SARS-CoV-2 vaccines in late 2020 substantially changed the pandemic picture, inducing effective protection in the population. However, individual variability was observed with different levels of cellular response and neutralizing antibodies. We report data on the impact of age, gender, and 16 single nucleotide polymorphisms (SNPs) of cytokine genes on the anti-SARS-CoV-2 IgG titers measured 31 and 105 days after administration of the second dose of BNT162b2 vaccine to 122 healthy subjects from the health care staff of the Palermo University Hospital, Italy. The higher titers at 31 days were measured in the younger subjects and in subjects bearing T-positive genotypes of IL-1R1 rs2234650 or the GG homozygous genotype of IL-6 rs1800795 SNP. T-positive genotypes are also significantly more common in subjects with higher titers at day 105. In addition, in this group of subjects, the frequency of the CT genotype of IL-4 rs2243250 is higher among those vaccinated with higher titers. Moreover, these SNPs and TNFA rs1800629 are differently distributed in a group of subjects that were found infected by SARS-CoV-2 at day 105 of evaluation. Finally, subjects that were found to be infected by SARS-CoV-2 at day 105 were significantly older than the uninfected subjects. Taken together, these data seem to suggest that age and polymorphisms of key cytokines, which regulate inflammation and humoral immune response, might influence the magnitude of the antibody response to vaccination with BNT162B2, prompting speculation about the possible benefit of a genetic background-based assessment of a personalized approach to the anti-COVID vaccination schedule.

Blood leukocyte transcriptional modules and differentially expressed genes associated with disease severity and age in COVID-19 patients

Since the molecular mechanisms determining COVID-19 severity are not yet well understood, there is a demand for biomarkers derived from comparative transcriptome analyses of mild and severe cases, combined with patients' clinico-demographic and laboratory data. Here the transcriptomic response of human leukocytes to SARS-CoV-2 infection was investigated by focusing on the differences between mild and severe cases and between age subgroups (younger and older adults). Three transcriptional modules correlated with these traits were functionally characterized, as well as 23 differentially expressed genes (DEGs) associated to disease severity. One module, correlated with severe cases and older patients, had an overrepresentation of genes involved in innate immune response and in neutrophil activation, whereas two other modules, correlated with disease severity and younger patients, harbored genes involved in the innate immune response to viral infections, and in the regulation of this response. This transcriptomic mechanism could be related to the better outcome observed in younger COVID-19 patients. The DEGs, all hyper-expressed in the group of severe cases, were mostly involved in neutrophil activation and in the p53 pathway, therefore related to inflammation and lymphopenia. These biomarkers may be useful for getting a better stratification of risk factors in COVID-19.

Impact of gender-affirming hormone therapy on the development of COVID-19 infections and associated complications: A systematic review

BACKGROUND

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can produce a wide range of clinical manifestations from asymptomatic to life-threatening. Various researchers have worked to elucidate the pathogenic mechanisms underlying these variable presentations. Differences in individual responses to systemic inflammation and coagulopathy appear to be modulated by several factors, including sex steroid hormones. Transgender men or non-binary individuals who undergo gender-affirming hormone therapy (GAHT) are a unique population of interest for exploring the androgen-mediated coronavirus disease 2019 (COVID-19) hypothesis. As the search for reliable and effective COVID-19 treatments continues, understanding the risks and benefits of GAHT may mitigate COVID-19 related morbidity and mortality in this patient population.

AIM

To investigate the potential role of GAHT in the development of COVID-19 infections and complications.

METHODS

This systematic review implemented an algorithmic approach using PRISMA guidelines. PubMed, Scopus, Google Scholar top 100 results, and archives of Plastic and Reconstructive Surgery was on January 12, 2022 using the key words "gender" AND "hormone" AND "therapy" AND "COVID-19" as well as associated terms. Non-English articles, articles published prior to 2019 (prior to COVID-19), and manuscripts in the form of reviews, commentaries, or letters were excluded. References of the selected publications were screened as well.

RESULTS

The database search resulted in the final inclusion of 14 studies related to GAHT COVID-19. Of the included studies, only two studies directly involved and reported on COVID-19 in transgender patients. Several clinical trials looked at the relationship between testosterone, estrogen, and progesterone in COVID-19 infected cis-gender men and women. It has been proposed that androgens may facilitate initial COVID-19 infection, however, once this occurs, testosterone may have a protective effect. Multiple clinical studies have shown that low baseline testosterone levels in men with COVID-19 are associated with worsening outcomes. The role of female sex hormones, including estrogen and progesterone have also been proposed as potential protective factors in COVID-19 infection. This was exemplified in multiple studies investigating different outcomes in pre- and post-menopausal women as well as those taking hormone replacement therapy. Two studies related specifically to transgender patients and GAHT found that estrogen and progesterone could help protect men against COVID-19, and that testosterone hormone therapy may increase the risk of contracting COVID-19.

CONCLUSION

Few studies were found related to the role of GAHT in COVID-19 infections. Additional research is necessary to enhance our understanding of this relationship and provide better care for transgender patients.

Humoral and cellular immune response after severe acute respiratory syndrome coronavirus 2 messenger ribonucleic acid vaccination in heart transplant recipients: An observational study in France

INTRODUCTION

Heart transplant (HT) recipients have a high risk of developing severe COVID-19. Immunoglobulin G antibodies are considered to provide protective immunity and T-cell activity is thought to confer protection from severe disease. However, data on T-cell response to mRNA vaccination in a context of HT remains limited.

METHODS

In 96 HT patients, a IFN-γ release assay and an anti-Spike antibody test were used to evaluate the ability of SARS-CoV-2 mRNA vaccines to generate cellular and humoral immune response. Blood samples were collected few weeks to 7 months after vaccination. Multiple fractional polynomial and LASSO regression models were used to define predictors of T-cell response.

RESULTS

Three to five months after vaccination, three doses of vaccine induced a positive SARS-CoV-2 T-cell response in 47% of recipients and a positive humoral response in 83% of recipients, 11.1% of patients remained negative for both T and B cell responses. Three doses were necessary to reach high IgG response levels (>590 BAU/mL), which were obtained in a third of patients. Immunity was greatly amplified in the group who had three vaccine doses plus COVID-19 infection.

CONCLUSION

Our study revealed that T and B immunity decreases over time, leading us to suggest the interest of a booster vaccination at 5 months after the third dose. Moreover, a close follow-up of immune response following vaccination is needed to ensure ongoing immune protection. We also found that significant predictors of higher cellular response were infection and active smoking, regardless of immunosuppressive treatment with mycophenolate mofetil (MMF).

Adaptive immunity to SARS-CoV-2 infection: A systematic review

Background

There is evidence that the adaptive or acquired immune system is one of the crucial variables in differentiating the course of coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This work aimed to analyze the immunopathological aspects of adaptive immunity that are involved in the progression of this disease.

Methods

This is a systematic review based on articles that included experimental evidence from in vitro assays, cohort studies, reviews, cross-sectional and case-control studies from PubMed, SciELO, MEDLINE, and Lilacs databases in English, Portuguese, or Spanish between January 2020 and July 2022.

Results

Fifty-six articles were finalized for this review. CD4+ T cells were the most resolutive in the health-disease process compared with B cells and CD8+ T lymphocytes. The predominant subpopulations of T helper lymphocytes (Th) in critically ill patients are Th1, Th2, Th17 (without their main characteristics) and regulatory T cells (Treg), while in mild cases there is an influx of Th1, Th2, Th17 and follicular T helper cells (Tfh). These cells are responsible for the secretion of cytokines, including interleukin (IL) - 6, IL-4, IL-10, IL-7, IL-22, IL-21, IL-15, IL-1α, IL-23, IL-5, IL-13, IL-2, IL-17, tumor necrosis factor alpha (TNF-α), CXC motivating ligand (CXCL) 8, CXCL9 and tumor growth factor beta (TGF-β), with the abovementioned first 8 inflammatory mediators related to clinical benefits, while the others to a poor prognosis. Some CD8+ T lymphocyte markers are associated with the severity of the disease, such as human leukocyte antigen (HLA-DR) and programmed cell death protein 1 (PD-1). Among the antibodies produced by SARS-CoV-2, Immunoglobulin (Ig) A stood out due to its potent release associated with a more severe clinical form.

Conclusions

It is concluded that through this study it is possible to have a brief overview of the main immunological biomarkers and their function during SARS-CoV-2 infection in particular cell types. In critically ill individuals, adaptive immunity is varied, aberrantly compromised, and late. In particular, the T-cell response is also an essential and necessary component in immunological memory and therefore should be addressed in vaccine formulation strategies.

SARS-CoV-2 and HIV-1: So Different yet so Alike. Immune Response at the Cellular and Molecular Level

In the past half century, humanity has experienced two devastating pandemics; the HIV-1 pandemic and the recent pandemic caused by SARS-CoV-2. Both emerged as zoonotic pathogens. Interestingly, SARS-CoV-2 has rapidly migrated all over the world in less than two years, much as HIV-1 did almost 40 years ago. Despite these two RNA viruses being different in their mode of transmission as well as the symptoms they generate, recent evidence suggests that they cause similar immune responses. In this mini review, we compare the molecular basis for CD4+ T cell lymphopenia and other effects on the immune system induced by SARS-CoV-2 and HIV-1 infections. We considered features of the host immune response that are shared with HIV-1 and could account for the lymphopenia and other immune effects observed in COVID-19. The information provided herein, may cast the virus-induced lymphopenia and cytokine storm associated with the acute SARS-CoV-2 infection and pathogenesis in a different light for further research on host immune responses. It can also provide opportunities for the identification of novel therapeutic targets for COVID-19. Furthermore, we provide some basic information to enable a comparative framework for considering the overlapping sets of immune responses caused by HIV-1 and SARS-CoV-2.

COVID-19 pandemic: A multidisciplinary perspective on the pathogenesis of a novel coronavirus from infection, immunity and pathological responses

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus2 (SARS-CoV-2), has spread to more than 200 countries and regions, having a huge impact on human health, hygiene, and economic activities. The epidemiological and clinical phenotypes of COVID-19 have increased since the onset of the epidemic era, and studies into its pathogenic mechanisms have played an essential role in clinical treatment, drug development, and prognosis prevention. This paper reviews the research progress on the pathogenesis of the novel coronavirus (SARS-CoV-2), focusing on the pathogenic characteristics, loci of action, and pathogenic mechanisms leading to immune response malfunction of SARS-CoV-2, as well as summarizing the pathological damage and pathological manifestations it causes. This will update researchers on the latest SARS-CoV-2 research and provide directions for future therapeutic drug development.

Publication trends of research on COVID-19 and host immune response: A bibliometric analysis

Introduction

As the first bibliometric analysis of COVID-19 and immune responses, this study will provide a comprehensive overview of the latest research advances. We attempt to summarize the scientific productivity and cooperation across countries and institutions using the bibliometric methodology. Meanwhile, using clustering analysis of keywords, we revealed the evolution of research hotspots and predicted future research focuses, thereby providing valuable information for the follow-up studies.

Methods

We selected publications on COVID-19 and immune response using our pre-designed search strategy. Web of Science was applied to screen the eligible publications for subsequent bibliometric analyses. GraphPad Prism 8.0, VOSviewer, and CiteSpace were applied to analyze the research trends and compared the contributions of countries, authors, institutions, and journals to the global publications in this field.

Results

We identified 2,200 publications on COVID-19 and immune response published between December 1, 2019, and April 25, 2022, with a total of 3,154 citations. The United States (611), China (353), and Germany (209) ranked the top three in terms of the number of publications, accounting for 53.3% of the total articles. Among the top 15 institutions publishing articles in this area, four were from France, four were from the United States, and three were from China. The journal Frontiers in Immunology published the most articles (178) related to COVID-19 and immune response. Alessandro Sette (31 publications) from the United States were the most productive and influential scholar in this field, whose publications with the most citation frequency (3,633). Furthermore, the development and evaluation of vaccines might become a hotspot in relevant scope.

Conclusions

The United States makes the most indispensable contribution in this field in terms of publication numbers, total citations, and H-index. Although publications from China also take the lead regarding quality and quantity, their international cooperation and preclinical research need to be further strengthened. Regarding the citation frequency and the total number of published articles, the latest research progress might be tracked in the top-ranking journals in this field. By analyzing the chronological order of the appearance of retrieved keywords, we speculated that vaccine-related research might be the novel focus in this field.

Antibodies to the Spike Protein Receptor-Binding Domain of SARS-CoV-2 at 4-13 Months after COVID-19

Identification of factors behind the level and duration of persistence of the SARS-CoV-2 antibodies in the blood is assumed to set the direction for studying humoral immunity mechanisms against COVID-19, optimizing the strategy for vaccine use, antibody-based drugs, and epidemiological control of COVID-19. Objective: This study aimed to study the relationship between clinical and demographic characteristics and the level of IgG antibodies to the RBD of SARS-CoV-2 spike protein after COVID-19 in the long term. Residents of the Altai Region of Western Siberia of Russia, Caucasians, aged from 27 to 93 years (median 53.0 years), who recovered from COVID-19 between May 2020 and February 2021 (n = 44) took part in this prospective observational study. The titer of IgG antibodies to the RBD of SARS-CoV-2 spike protein was measured repeatedly in the blood at 4-13 months from the beginning of the clinical manifestation of COVID-19 via the method of enzyme-linked immunosorbent assay. The antibody titer positively correlated with age (p = 0.013) and COVID-19 pneumonia (p = 0.002) at 20-40 and 20-24 weeks from the onset of COVID-19 symptoms, respectively. Age was positively associated with antibody titer regardless of history of COVID-19 pneumonia (beta regression coefficient p = 0.009). The antibody titer decreased in 15 (34.1%) patients, increased in 10 (22.7%) patients, and did not change in 19 (43.2%) patients from the baseline to 48-49 weeks from the onset of COVID-19 symptoms, with seropositivity persisting in all patients. Age and COVID-19 pneumonia are possibly associated with higher IgG antibodies to the spike protein RBD of SARS-CoV-2 following COVID-19 in the long term. Divergent trends of anti-RBD IgG levels in adults illustrate inter-individual differences at 4-13 months from the onset of COVID-19 symptoms.

SCD14-ST and New Generation Inflammatory Biomarkers in the Prediction of COVID-19 Outcome

Since no definitive cure for COVID-19 is available so far, one of the challenges against the disease is understanding the clinical features and the laboratory inflammatory markers that can differentiate among different severity grades of the disease. The aim of the present study is a comprehensive and longitudinal evaluation of SCD14-ST and other new inflammatory markers, as well as cytokine storm molecules and current inflammatory parameters, in order to define a panel of biomarkers that could be useful for a better prognostic prediction of COVID-19 mortality. SCD14-ST, as well as the inflammatory markers IL-6, IL-10, SuPAR and sRAGE, were measured in plasma-EDTA of ICU COVID-19 positive patients. In this longitudinal study, SCD14-ST resulted significantly higher in patients who eventually died compared to those who were discharged from the ICU. The results suggest that the new infection biomarker SCD14-ST, in addition to new generation inflammatory biomarkers, such as SuPAR, sRAGE and the cytokines IL-6 and IL-10, can be a useful prognostic tool associated with canonical inflammatory parameters, such as CRP, to predict SARS-CoV-2 outcome in ICU patients.

The enemy is the virus, not the vaccine

If we remember very superficially a little about the complex human immune system, a part of this immune system is made up of leukocytes (especially phagocytes and lymphocytes) that are responsible for detecting invaders and sending them defensive markers that adhere to them (the antibodies) and also to destroy the invaders identified by the system; In addition to the already mentioned leukocytes, our immune system is made up of various other elements such as cells, proteins, tissues and organs, which defend us against germs and microorganisms. 1, 2 Speaking specifically about the immune system and COVID-19, the events mainly involved in the immunopathogenesis of COVID-19 and the dysregulation of the immune response include lymphopenia and increased neutrophil-to-lymphocyte ratio, cytokines, lymphocyte depletion and dysfunction, antibody-dependent enhancement, and monocyte and granulocyte abnormalities. It must be emphasized that lymphopenia is an essential finding in most patients with COVID-19, particularly in those with a severe phenotype.3 It has been shown that multiple viral proteins induce T cells after infection and that T cells that have antiviral signatures related to safety and protection can be achieved by vaccination.4

The mechanism underlying extrapulmonary complications of the coronavirus disease 2019 and its therapeutic implication

The coronavirus disease 2019 (COVID-19) is a highly transmissible disease caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that poses a major threat to global public health. Although COVID-19 primarily affects the respiratory system, causing severe pneumonia and acute respiratory distress syndrome in severe cases, it can also result in multiple extrapulmonary complications. The pathogenesis of extrapulmonary damage in patients with COVID-19 is probably multifactorial, involving both the direct effects of SARS-CoV-2 and the indirect mechanisms associated with the host inflammatory response. Recognition of features and pathogenesis of extrapulmonary complications has clinical implications for identifying disease progression and designing therapeutic strategies. This review provides an overview of the extrapulmonary complications of COVID-19 from immunological and pathophysiologic perspectives and focuses on the pathogenesis and potential therapeutic targets for the management of COVID-19.

Complement inhibition: A possible therapeutic approach in the fight against Covid-19

The complement system, as a vital part of innate immunity, has an important role in the clearance of pathogens; however, unregulated activation of this system probably has a key role in the pathogenesis of acute lung injury, which is induced by highly pathogenic viruses (i.e. influenza A viruses and severe acute respiratory syndrome [SARS] coronavirus). The novel coronavirus SARS-CoV-2, which is the causal agent for the ongoing global pandemic of the coronavirus disease 2019 (Covid-19), has recently been spread to almost all countries around the world. Although most people are immunocompetent to SARS-CoV-2, a small group develops hyper-inflammation that leads to complications like acute respiratory distress syndrome, disseminated intravascular coagulation, and multi-organ failure. Emerging evidence demonstrates that the complement system exerts a crucial role in this inflammatory reaction. Additionally, patients with the severe form of Covid-19 show over-activation of the complement in their skin, sera, and lungs. This study aims to summarise current knowledge concerning the interaction of SARS-CoV-2 with the complement system and to critically appraise complement inhibition as a potential new approach for Covid-19 treatment.

SARS-CoV-2 variants in severely symptomatic and deceased persons who had been vaccinated against COVID-19 in São Paulo, Brazil

COVID-19 vaccination began in São Paulo, Brazil in January 2021, first targeting healthcare workers (HCWs) and the elderly, using the CoronaVac vaccine (Sinovac/Butantan) and subsequently the Oxford/AstraZeneca (ChAdOx1) vaccine (AstraZeneca/FIOCRUZ-RJ). Studies on such vaccines have shown efficacy in preventing severe cases and deaths, but there is a lack of information regarding their effectiveness. This manuscript presents data from the Instituto Adolfo Lutz (IAL), a public health laboratory located in São Paulo City that receives samples from 17 Regional Health Departments under the Secretary of Health of São Paulo, for SARS-CoV-2 genomic surveillance. Through May 15, 2021 IAL received 20 samples for analysis from COVID-19 vaccinated individuals who needed hospitalization and/or died from COVID-19. Next-generation sequencing was performed on an Ion Torrent S5 platform using the AmpliSeq™ SARS-CoV-2 kit. Almost all cases were vaccinated with CoronaVac and presented the gamma variant of concern (VOC). Cases of death were observed mostly in the elderly in nursing homes, and severe cases in younger frontline HCWs. This data confirmed that the SARS-CoV-2 gamma variant is highly transmissible, severe, and lethal for COVID-19 in these groups of individuals, thereby highlighting the importance of continuous vaccination and non-pharmacological prevention measures to avoid virus dissemination and the emergence of new VOCs.

Factors Affecting the Antibody Immunogenicity of Vaccines against SARS-CoV-2: A Focused Review

Vaccines are a crucial part of the global anti-pandemic effort against COVID-19. The effects of vaccines, as well as their common influencing factors, are the most important issues that we should focus on at this time. To this end, we review statistics on immunogenicity after vaccination, using neutralizing antibodies as the main reference index. Age, infection history, and virus variants are compared, and vaccination program recommendations are made accordingly. Suggestions are made to address concerns raised by the vaccines' shortened development cycle, as well as the emergence of immunity escape of viral variants. Finally, a brief description and future prospects are provided based on the principle of the ADE effect and previous experience with similar viruses.

Expression of innate immune response genes in upper airway samples of SARS-CoV-2 infected patients: A preliminary study

Background & objectives

Upper respiratory mucosa is the entryway for SARS-CoV-2, and cells at this site form the first line of resistance against the pathogens. Innate immune response at this point is crucial for managing the replication and early stage symptoms of virus infection. This study was aimed to evaluate the expression of pattern recognition receptors and cytokines in upper airway cells of SARS-CoV-2 infected patients.

Methods

Forty seven nasopharyngeal swab (NPS) specimens from 25 SARS-CoV-2 infected patients and 22 SARS-CoV-2 negative individuals were investigated for expression of toll-like receptors (TLRs), melanoma differentiation-associated protein 5 (MDA5), NOD-like receptors family pyrin domain containing 3 (NLRP3), angiotensin-converting enzyme 2 (ACE2), interleukin (IL) - 6, tumour necrosis factor alpha (TNFα) and type-1 interferons (IFNs) by real time reverse transcription polymerase chain reaction.

Results

Increased expression of TLR2, MDA5 and ACE2 was detected in SARS-CoV-2 infected patients in comparison with controls. MDA5 expression was significantly higher in asymptomatic and mildly symptomatic SARS-CoV-2 positive patients than the patients with severe symptoms. The asymptomatic group showed significant induction of type 1 IFNs than the symptomatic group. Non-specific induction of TLR7 could be observed in nasopharyngeal (NP) cells irrespective of symptoms and SARS-CoV-2 positivity.

Interpretation & conclusions

The findings suggest that increased MDA5 in NP cells of asymptomatic SARS-CoV-2 positive patients may subsequently induce type 1 IFNs to protect the individuals from further clinical severity of SARS-CoV-2 infection. A future prospective study in NPS of larger cohort needs to be performed to confirm our findings.