Expression of lymphocytes and lymphocyte subsets in patients with severe acute respiratory syndrome

Tuberculosis Trends in the Post-COVID-19 Era: Is It Going to be a Global Concern?

Background and Aims

Tuberculosis (TB), a leading cause of death from infectious diseases, faced considerable challenges during the coronavirus disease 2019 (COVID-19) pandemic. This review examines the impact of pandemic-related disruptions, including the diversion of healthcare resources, reduced access to TB diagnostics and treatment, and declining BCG vaccination rates, on TB trends. The aim is to forecast the post-COVID-19 TB burden, identify risk factors that exacerbate transmission, and propose strategies to prevent a global resurgence.

Methods

This narrative review incorporates epidemiological data, modeling research, and reports from the World Health Organization and national health systems. It examines TB trends before and after COVID-19, the outcomes of coinfection, and the pandemic's impact on immunology, socioeconomic factors, and health systems. The review also compares trends in India and South Africa-two countries facing significant challenges-to those observed during the COVID-19 pandemic.

Results

COVID-19 disruptions in healthcare led to an 18% decrease in TB notifications in 2020, resulting in delayed diagnoses, increased household transmission, and higher mortality. Immune dysregulation, including T-cell depletion and cytokine storms, contributed to a 12.3% mortality rate in COVID-19-TB coinfections. Models predict a 5%-15% rise in TB incidence and an additional 1.4 million deaths by 2025. Individuals with HIV, diabetes, and malnutrition were particularly vulnerable. Factors such as overcrowding, air pollution, and reduced Bacillus Calmette-Guérin (BCG) coverage in endemic regions have further heightened susceptibility to TB.

Conclusion

COVID-19 has undone years of progress in TB control, highlighting the need for a unified health strategy. Early diagnosis, treatment of latent TB, and BCG catch-up initiatives are crucial. Strengthening health systems, addressing socioeconomic factors such as poverty and hunger, and utilizing pandemic advancements like telemedicine and vaccine research will be key to preventing a resurgence of TB. Continued financial support and international cooperation are essential to eliminating TB by 2030.

Verbenalin protects against coronavirus pneumonia by promoting host immune homeostasis: Evidences for its mechanism of action

BACKGROUND

Coronavirus has caused high-mortality viral pneumonia worldwide. The pathogenesis is characterized by hyperinflammatory reactions resulting from immune homeostasis dysregulation. Verbenalin, an iridoid glucoside derived from Verbena officinalis L., is widely used in Traditional Chinese Medicine (TCM) clinical practice for its antioxidant, anti-inflammatory and antiviral properties.

PURPOSE

This study aimed to investigate the pharmacological effects and underlying mechanisms of verbenalin on coronavirus pneumonia both in vivo and in vitro.

METHODS

A coronavirus pneumonia mouse model and macrophage injury models, including mouse alveolar macrophage cell line (MH-S) cells and primary macrophages, were established to initially confirm the antiviral effects of verbenalin. Time-resolved proteomic were then employed to uncover proteomic changes and identify potential therapeutic targets for coronavirus treatment. Subsequently, flow cytometry and Western blot were employed to investigate verbenalin's effects on NOD-, LRR- and pyrin domain-containing protein 3 (NLRP3) inflammasome pathway. Additionally, the targeting regulation of phosphatase and tensin homolog-induced putative kinase 1 (PINK1) / E3 ubiquitin ligase Parkin (Parkin) pathway by verbenalin was validated through molecular docking, surface plasmon resonance (SPR), immunofluorescent staining, RNA interference (RNAi), and mitophagy inhibition both in vivo and in vitro.

RESULTS

Verbenalin reduced cell injury and inflammation in Human coronavirus 229E (HCoV-229E)-infected macrophages and improved lung inflammation in mice. Proteomics analysis highlighted the roles of nucleotide-binding oligomerization domain (NOD)-like receptor signaling and mitophagy pathways in coronavirus pneumonia. Verbenalin bound strongly to PINK1 and Parkin proteins, increased mitochondrial membrane potential (MMP), decreased mitochondrial reactive oxygen species (mtROS) levels, reduced the opening of mitochondrial permeability transition pore (MPTP), maintained mitochondrial mass, promoted mitophagy flux, upregulated the expression of PINK1, Parkin, and microtubule-associated protein 1A/1B-light chain 3BII (LC3BII). Additionally, verbenalin inhibited the activation of the NLRP3 inflammasome and downregulated the expression of Interleukin-1 beta (IL-1β), cysteine aspartate-specific protease 1 (caspase-1), and gasdermin D (GSDMD) both in vivo and in vitro. Furthermore, treatment with a mitophagy inhibitor and RNAi attenuated the inhibitory effects of verbenalin on NLRP3 activation, confirming the involvement of the PINK1/Parkin/NLRP3 pathway in verbenalin's protective effects.

CONCLUSION

Verbenalin enhances PINK1/Parkin-mediated mitophagy to suppress NLRP3 activation, thereby promoting immune homeostasis and mitigating HCoV-229E-induced inflammation.

NK cells modulate in vivo control of SARS-CoV-2 replication and suppression of lung damage

Natural killer (NK) cells play a critical role in virus control. However, it has remained largely unclear whether NK cell mobilization in SARS-CoV-2 infections is beneficial or pathologic. To address this deficit, we employed a validated experimental NK cell depletion non-human primate (NHP) model with SARS-CoV-2 Delta variant B.1.617.2 challenge. Viral loads (VL), NK cell numbers, activation, proliferation, and functional measures were evaluated in blood and tissues. In non-depleted (control) animals, infection rapidly induced NK cell expansion, activation, and increased tissue trafficking associated with VL. Strikingly, we report that experimental NK cell depletion leads to higher VL, longer duration of viral shedding, significantly increased levels of pro-inflammatory cytokines in the lungs, and overt lung damage. Overall, we find the first significant and conclusive evidence for NK cell-mediated control of SARS-CoV-2 virus replication and disease pathology. These data indicate that adjunct therapies for infection could largely benefit from NK cell-targeted approaches.

Association of KIR Genes with Middle East Respiratory Syndrome Coronavirus Infection in South Koreans

BACKGROUND

Middle East respiratory syndrome (MERS) is a lower respiratory tract disease caused by a beta coronavirus (CoV) called MERS-CoV, characterized by a high mortality rate. We aimed to evaluate the association between genetic variation in killer cell immunoglobulin-like receptors (KIRs) and the risk of MERS in South Koreans.

METHODS

KIR genes were genotyped by multiplex polymerase chain reaction with sequence-specific primers (PCR-SSP). A case-control study was performed to identify the odds ratios (OR) of KIR genes for MERS and the association of KIR genes and their ligands, human leukocyte antigens (HLA) genes.

RESULTS

KIR2DS4D and KIR3DP1F showed higher frequencies in the group of all patients infected with MERS-CoV than in the control group (p = 0.023, OR = 2.4; p = 0.039, OR = 2.7). KIR2DL1, KIR2DP1, and KIR3DP1D were significantly associated with moderate/mild (Mo/Mi) cases. KIR2DL2, KIR2DS1, and KIR3DP1F were affected in severe cases. When we investigated the association between KIR genes and their ligands in MERS patient and control groups, KIR3DL1+/Bw4(80I)+, KIR3DL1+/Bw6+, KIR3DL1+/Bw6-, KIR2DS1+/C2+, and KIR3DS+/Bw4(80I)+ were associated with MERS. KIR3DL1+/Bw6- was found in Mo/Mi cases. KIR2DS1+/C2+ and KIR2DS2+/C1+ were found in severe cases.

CONCLUSION

Further investigations are needed to prove the various immune responses of MERS-CoV-infected cells according to variations in the KIR gene and ligand gene. A treatment strategy based on current research on the KIR gene and MERS-CoV will suggest potential treatment targets.

Incompetent memory immune response in severe COVID-19 patients under treatment

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) associated coronavirus disease 2019 (COVID-19) pandemic has affected millions of people worldwide and declared a Public Health Emergency by the World Health Organization (WHO) on January 30, 2020. Albeit, unprecedented efforts have been made from the scientific community to understand the pathophysiology of COVID-19 disease, the host immune and inflammatory responses are not explored well in the Indian population. Continuous arrival of new variants fascinated the scientists to understand the host immune processes and to eradicate this deadly virus. The aim of this study was to see the helper and cellular host immune responses including memory and activated cell subsets of COVID-19 patients admitted to the intensive care unit (ICU) at different time intervals during the treatment. PBMCs separated from nine patients with SARS-CoV-2 infection were incubated with fluorescent conjugated antibodies and acquired on flow cytometer machine to analyze the T and B cell subsets. The results in COVID-19 patients versus healthy volunteers were as follows: elevated helper T cells (57.4% vs 44.9%); low cytotoxic T cells (42.8% vs 55.6%), and activated T (17.7% vs 21.2%) subsets. Both, TREG (40.15% vs 51.7%) and TH17 (13.2% vs 24.6%) responses were substantially decreased and high expression of TREG markers was observed in these patients compared with controls.

Immunometabolic interference between cancer and COVID-19

Even though cancer patients are generally considered more susceptible to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, the mechanisms driving their predisposition to severe forms of coronavirus disease 2019 (COVID-19) have not yet been deciphered. Since metabolic disorders are associated with homeostatic frailty, which increases the risk of infection and cancer, we asked whether we could identify immunometabolic pathways intersecting with cancer and SARS-CoV-2 infection. Thanks to a combined flow cytometry and multiomics approach, here we show that the immunometabolic traits of COVID-19 cancer patients encompass alterations in the frequency and activation status of circulating myeloid and lymphoid subsets, and that these changes are associated with i) depletion of tryptophan and its related neuromediator tryptamine, ii) accumulation of immunosuppressive tryptophan metabolites (i.e., kynurenines), and iii) low nicotinamide adenine dinucleotide (NAD+) availability. This metabolic imbalance is accompanied by altered expression of inflammatory cytokines in peripheral blood mononuclear cells (PBMCs), with a distinctive downregulation of IL-6 and upregulation of IFNγ mRNA expression levels. Altogether, our findings indicate that cancer not only attenuates the inflammatory state in COVID-19 patients but also contributes to weakening their precarious metabolic state by interfering with NAD+-dependent immune homeostasis.

T-cell lymphocytopenia: an omnipresent predictor of morbidity and mortality in consequence of SARS-CoV disease and influenza A infections

We proposed T-cell lymphocytopenia as a strategic predictor of serious coronavirus and influenza infections. Our preeminent goal was to determine whether a degree of T-cell lymphopenia would identify a distinct threshold cell count to differentiate between severe and non-severe infections. We codified an Index Severity Score to exploit an association between T-cell cytopenia and the grade of disease activity.

Principal result

A T-cell count of 560 cells/uL or below signified a trend towards advanced disease.

Key findings and conclusions

The T-cell threshold >560 cells/uL discriminated 85.7% specificity of the lesser viral infections and <=560 cells/uL identified 100% sensitivity of severe infections or death. The positive predictive value of this threshold test was 92.9%.•

T-cell apoptosis and sequestration are two of the primary mechanisms of T-cell lymphodepletion.

•

There is potential for the T-cell threshold at <=560 cells/uL to become a standard to differentiate disease severity.

•

Future research should explore correlations between the T-cell threshold, medical outcomes of treatment, Cytokine Release Syndromes, cytokine levels, inflammatory and coagulation markers.

Natural killer cells in COVID-19: from infection, to vaccination and therapy

Natural killer (NK) cells are among the most important innate immunity members, which are the first cells that fight against infected cells. The function of these cells is impaired in patients with COVID-19 and they are not able to prevent the spread of the disease or destroy the infected cells. Few studies have evaluated the effects of COVID-19 vaccines on NK cells, though it has been demonstrated that DNA vaccines and BNT162b2 can affect NK cell response. In the present paper, the effects of SARS-CoV-2 on the NK cells during infection, the effect of vaccination on NK cells, and the NK cell-based therapies were reviewed.

Characteristics of lymphocyte subset alterations in COVID-19 patients with different levels of disease severity

Background

Coronavirus disease 2019 (COVID-19) is a respiratory disorder caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which had rapidly spread all over the world and caused public health emergencies in the past two years. Although the diagnosis and treatment for COVID-19 have been well defined, the immune cell characteristics and the key lymphocytes subset alterations in COVID-19 patients have not been thoroughly investigated.

Methods

The levels of immune cells including T cells, B cells, and natural killer (NK) cells in 548 hospitalized COVID-19 patients, and 30 types of lymphocyte subsets in 125 hospitalized COVID-19 patients admitted to Wuhan Huoshenshan Hospital of China were measured using flow cytometry. The relationship between lymphocytes subsets with the cytokine interleukin-6 (IL-6) and the characteristics of lymphocyte subsets in single-cell RNA sequencing (scRNA-seq) data obtained from peripheral blood mononuclear cells (PBMCs) were also analysed in COVID-19 patients.

Results

In this study, we found that patients with critical COVID-19 infection exhibited an overall decline in lymphocytes including CD4+ T cells, CD8+ T cells, total T cells, B cells, and NK cells compared to mild and severe patients. However, the number of lymphocyte subsets, such as CD21low CD38low B cells, effector T4 cells, and PD1+ depleted T8 cells, was moderately increased in critical COVID-19 patients compared to mild cases. Notably, except for effector memory T4 cells, plasma blasts and Tregs, the number of all lymphocyte subsets was markedly decreased in COVID-19 patients with IL-6 levels over 30-fold higher than those in healthy cases. Moreover, scRNA-seq data showed obvious differences in the distribution and numbers of lymphocyte subsets between COVID-19 patients and healthy persons, and subsets-specific marker genes of lymphocyte subsets including CD4, CD19, CCR7, and IL7R, were markedly decreased in COVID-19 patients compared with those in healthy cases.

Conclusion

A comprehensive decrease in immune cell and lymphocyte subsets in critical COVID-19 patients, and peripheral lymphocyte subset alterations showed a clear association with clinical characteristics.

Plant Molecular Pharming and Plant-Derived Compounds towards Generation of Vaccines and Therapeutics against Coronaviruses

The current century has witnessed infections of pandemic proportions caused by Coronaviruses (CoV) including severe acute respiratory syndrome-related CoV (SARS-CoV), Middle East respiratory syndrome-related CoV (MERS-CoV) and the recently identified SARS-CoV2. Significantly, the SARS-CoV2 outbreak, declared a pandemic in early 2020, has wreaked devastation and imposed intense pressure on medical establishments world-wide in a short time period by spreading at a rapid pace, resulting in high morbidity and mortality. Therefore, there is a compelling need to combat and contain the CoV infections. The current review addresses the unique features of the molecular virology of major Coronaviruses that may be tractable towards antiviral targeting and design of novel preventative and therapeutic intervention strategies. Plant-derived vaccines, in particular oral vaccines, afford safer, effectual and low-cost avenues to develop antivirals and fast response vaccines, requiring minimal infrastructure and trained personnel for vaccine administration in developing countries. This review article discusses recent developments in the generation of plant-based vaccines, therapeutic/drug molecules, monoclonal antibodies and phytochemicals to preclude and combat infections caused by SARS-CoV, MERS-CoV and SARS-CoV-2 viruses. Efficacious plant-derived antivirals could contribute significantly to combating emerging and re-emerging pathogenic CoV infections and help stem the tide of any future pandemics.

Fiber-enriched botanicals: A therapeutic tool against certain metabolic ailments

Plant-based foods are natural sources including vegetables, fruits, cereals and legumes. These foods consist of various types of nutrients in which carbohydrate is the basic component. However, some plant-based diets contain carbohydrates in the form of fiber. The fiber is usually a nondigestible polysaccharide that is not digested in the human body. It is present in the form of soluble or insoluble in different part of foods like peel, bran, pulp and grain. Pectin, beta-glucan, mucilage, psyllium, resistant starch and inulin are soluble fiber, and cellulose, hemicellulose and lignin are insoluble fiber attained from plant foods. The major function enhances immunity by creating gastrointestinal barrier, mucus production, immune cell activity and IgA level. Previous evidences showed that peoples with strong immunity have fewer chances of viral disease. A recent viral disease named COVID-19 spread in the world and millions of peoples died due to this viral disease. Coronavirus mostly attacks humans that suffer with weak immune system. It is due chronic diseases like diabetes and CVD (cardiovascular disease). The current review shows that fiber-containing plant-based foods boost immunity and aid human against COVID-19. The therapeutic role of fiber in the human body is to control the risk of hypertension and diabetes because a high-fiber diet has the ability to lower cholesterol, blood pressure and blood sugar. Fibers aid in GIT (gastrointestinal tract) and prevent constipation because it absorbs water and adds bulk to stool.

Immune features of COVID-19 convalescent individuals revealed by a single-cell RNA sequencing

It remains unclear whether immune responses following natural infection can be sustained or potentially prove critical for long-term immune protection against SARS-CoV-2 reinfection. Here, we systematically mapped the phenotypic landscape of SARS-CoV-2-specific immune responses in peripheral blood samples of convalescent patients with COVID-19 by single-cell RNA sequencing. The relative percentage of the CD8 + effector memory subset was increased in both convalescent moderate and severe cases, but NKT-CD160 and marginal zone B clusters were decreased. Innate immune responses were attenuated reflected by decreased expression of genes involved in interferon-gamma, leukocyte migration and neutrophil mediated immune response in convalescent COVID-19 patients. Functions of T cell were strengthened in convalescent COVID-19 patients by clear endorsement of increased expression of genes involved in biological processes of regulation of T cell activation, differentiation and cell-cell adhesion. In addition, T cell mediated immune responses were enhanced with remarkable clonal expansions of TCR and increased transition of CD4 + effector memory and CD8 + effector-GNLY in severe subjects. B cell immune responses displayed complicated and dualfunctions during convalescence of COVID-19, providing a novel mechanism that B cell activation was observed especially in moderate while humoral immune response was weakened. Interestingly, HLA class I genes displayed downregulation while HLA class II genes upregulation in both T and B cell subsets in convalescent individuals. Our results showed that innate immunity was declined but SARS-CoV-2-specific T cell responses were retained even strengthened whereas complicated and dualfunctions of B cells, including declined humoral immunity were presented at several months following infections.

Conceptual Framework for SARS-CoV-2-Related Lymphopenia

The emerging of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) outbreak is associated with high morbidity and mortality rates globally. One of the most prominent characteristics of coronavirus disease-19 (COVID-19) is lymphopenia, which is in contrast to other viral infections. This controversy might be explained by the evaluation of impaired innate and adaptive immune responses, during the SARS-CoV-2 infection. During the innate immune response, poly-ADP-ribose polymerase hyperactivated due to virus entry and extensive DNA damage sequentially, leading to nicotinamide adenine dinucleotide (NAD)+ depletion, adenosine triphosphate depletion, and finally cell death. In contrast to the immune response against viral infections, cytotoxic T lymphocytes decline sharply in SARS-CoV-2 infection which might be due to infiltration and trapping in the lower respiratory tract. In addition, there are more factors proposed to involve in lymphopenia in COVID-19 infection such as the role of CD38, which functions as NADase and intensifies NAD depletion, which in turn affects NAD+–dependent Sirtuin proteins, as the regulators of cell death and viability. Lung tissue sequestration following cytokine storm supposed to be another reason for lymphopenia in COVID-19 patients. Protein 7a, as one of the virus-encoded proteins, induces apoptosis in various organ-derived cell lines. These mechanisms proposed to induce lymphopenia, although there are still more studies needed to clarify the underlying mechanisms for lymphopenia in COVID-19 patients.

SARS-CoV-2 may affect the immune response via direct inhibition of T cell receptor: Mechanistic hypothesis and rationale

During co-evolution with their hosts, many viruses have evolved a membrane fusion mechanism to facilitate host cell entry. Examples are human immunodeficiency virus type 1 (HIV-1) and severe acute respiratory syndrome coronaviruses 1 and 2 (SARS-CoV-1 and SARS-CoV-2). These viruses can also infect immune cells (e.g., T cells), providing one of the possible mechanisms for the T cell lymphopenia observed in patients with these infections. Previously, we hypothesized and confirmed in vivo that like HIV-1, SARS-CoV-1 can use its fusion domain not only to enter the T cell but also to directly inhibit T cell receptor signaling. Here, based on the analysis of available structural and clinical data, we hypothesize that SARS-CoV-2 may use a similar "disarm the alarm" strategy to suppress immune responses. We also discuss the implications of this hypothesis for better understanding coronavirus disease 2019 (COVID-19) pathology, developing effective COVID-19 vaccines and improving clinical outcomes for COVID-19 patients.

β-Glucans Could Be Adjuvants for SARS-CoV-2 Virus Vaccines (COVID-19)

Waiting for an effective treatment against the SARS-CoV-2 virus (the cause of COVID-19), the current alternatives include prevention and the use of vaccines. At the moment, vaccination is the most effective strategy in the fight against pandemic. Vaccines can be administered with different natural biological products (adjuvants) with immunomodulating properties. Adjuvants can be taken orally, complementing vaccine action. Adjuvant compounds could play a key role in alleviating the symptoms of the disease, as well as in enhancing vaccine action. Adjuvants also contribute to an effective immune response and can enhance the protective effect of vaccines in immunocompromised individuals such as the elderly. Adjuvants must not produce adverse effects, toxicity, or any other symptoms that could alter immune system function. Vaccine adjuvants are substances of wide varying chemical structure that are used to boost the immune response against a simultaneously administered antigen. Glucans could work as adjuvants due to their immunomodulatory biological activity. In this respect, β-(1,3)-(1,6) glucans are considered the most effective and safe according to the list issued by the European Commission. Only glucans with a β-(1,3) bond linked to a β-(1,6) are considered modulators of certain biological responses. The aim of this review is to present the possible effects of β-glucans as adjuvants in the efficacy of vaccines against SARS-CoV-2 virus.

Lymphocyte count predicts the severity of COVID-19: Evidence from a meta-analysis

BACKGROUND

In December 2019, coronavirus disease 2019 (COVID-19) was reported firstly in Wuhan, China. COVID-19 is currently a global pandemic.

AIM

To assess the suitability of lymphocyte count as a biomarker of COVID-19 severity.

METHODS

Five literature databases (PubMed/MEDLINE, Web of Science, Google Scholar, Embase, and Scopus) were searched to identify eligible articles. A meta-analysis was performed to calculate the standard mean difference (SMD) and 95% confidence interval (CI) of lymphocyte counts in coronaviral pneumonia cases.

RESULTS

Eight studies, including 1057 patients, were integrated in the meta-analysis. Lymphocyte counts were associated with severe coronavirus (CoV) infection (SMD = 1.35, 95%CI: 1.97 to 0.37, P < 0.001, I² = 92.6%). In the subgroup analysis stratified by prognosis, lymphocytes were associated with CoV infection mortality (n = 2, SMD = 0.42, 95%CI: 0.66 to 0.19, P < 0.001, I² = 0.0%), severity (n = 2, SMD = 0.93, 95%CI: 1.20 to 0.67, P < 0.001, I² = 0.0%), and diagnostic rate (n = 4, SMD = 2.32, 95%CI: 3.60 to 1.04, P < 0.001, I² = 91.2%).

CONCLUSION

Lymphocyte count may represent a simple, rapid, and commonly available laboratory index with which to diagnosis infection and predict the severity of CoV infections, including COVID-19.

A Single Dose of SARS-CoV-2 Vaccine Primes a Strong Humoral Immune Response in COVID-19-Recovered Patients

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection causes coronavirus disease 2019 (COVID-19), which has affected hundreds of millions of people globally. The development of safe and effective vaccines represents an urgent demand. A total of 136 participants were recruited in this study, including 75 men and 61 women. The participants were divided into two groups: those who were virus naïve (never infected) and those who had recovered from COVID-19. Each group included individuals who received either the Pfizer-BioNTech BNT162b2 mRNA or the Oxford-AstraZeneca ChAdOx1 COVID-19 vaccine. Enzyme-linked immunosorbent assay (ELISA) was used to measure anti-S IgG antibody concentrations in sequential serum samples obtained before vaccine administration, after the first vaccine dose, and after the second vaccine dose. We compared the antibody responses of individuals with confirmed prior COVID-19 infection with those of individuals without prior evidence of infection. All participants who were previously infected with SARS-CoV-2 who received one dose of either the Pfizer-BioNTech BNT162b2 mRNA or the Oxford-AstraZeneca ChAdOx1 COVID-19 vaccine showed significant anti-S IgG antibody levels. No sex-related differences were observed when we compared antibody levels between men and women. In infection-naïve participants ≥60 years, a second vaccine dose was necessary to achieve higher levels of antibody when comparing the IgG antibody levels after receiving the first and second dose.

An association between immune status and chest CT scores in COVID-19 patients

BACKGROUND

The characteristic features of the immune responses of COVID-19 patients and how they reflect lung involvement have not been clearly elucidated.

AIM

The aim of this study was to examine the immune status and the correlations thereof with chest CT scores and lung involvement of patients with COVID-19.

METHODS

In this retrospective and single-center study, 72 patients with laboratory-confirmed COVID-19 were recruited. The counts of peripheral lymphocyte subsets (CD3⁺ T cells, CD4⁺ T cells, CD8⁺ T cells, CD19⁺ B cells and CD16⁺ 56⁺ NK cells) and those of serum immunoglobulins (IgA, IgG, IgM) were measured and their associations with chest CT scores analysed.

RESULTS

The proportions of lymphopenia in patients with extensive lung involvement were twice that in the general study population. In the severe disease group, the levels of total lymphocytes, T cells, B cells, NK cells; and serum IgA levels, were significantly lower than in the mild disease group (all P < .05). We found that the numbers of lymphocyte subsets and the IgA level negatively correlated with the chest CT scores. On multivariate regression analysis, pretreatment decreases in total lymphocytes, CD3⁺ T cells, CD4⁺ T cells, and CD19⁺ B cells, and serum IgA levels, were independent predictors of severe lung involvement.

CONCLUSIONS

The cell numbers of peripheral lymphocyte subsets and the serum IgA level were negatively correlated with the chest CT scores in COVID-19 patients. These parameters tended to independently predict severe lung involvement in such patients.

Molecular Insights into the Crosstalk Between Immune Inflammation Nexus and SARS-CoV-2 Virus

COVID-19, a type of viral pneumonia caused by severe acute respiratory syndrome coronavirus 2 has challenged the world as global pandemic. It has marked the identification of third generation of extremely pathogenic zoonotic coronaviruses of twenty-first century posing threat to humans and mainly targeting the lower respiratory tract. In this review, we focused on not only the structure and virology of SARS-COV-2 but have discussed in detail the molecular immunopathogenesis of this novel virus highlighting its interaction with immune system and the role of compromised or dysregulated immune response towards disease severity. We attempted to correlate the crosstalk between unregulated inflammatory outcomes with disrupted host immunity which may play a potential role towards fatal acute respiratory distress syndrome that claims to be life-threatening in COVID-19. Exploration and investigation of molecular host-virus interactions will provide a better understanding on the mechanism of fatal COVID-19 infection and also enlighten the escape routes from the same.

Vitamin D and COVID-19: An Overview of Recent Evidence

The novel coronavirus severe acute respiratory syndrome (SARS-CoV-2) has progressed rapidly from an outbreak to a global pandemic, with new variants rapidly emerging. Coronavirus disease 2019 (COVID-19), the disease resulting from SARS-CoV-2 infection, can lead to multiorgan damage. Due to the extremely contagious and fatal nature of the virus, it has been a priority of medical research to find effective means of treatment. Amid this search, the role of vitamin D in modulating various aspects of the innate and adaptive immune system has been discussed. This review aims to consolidate the research surrounding the role of vitamin D in the treatment and prevention of COVID-19. While there are some conflicting results reported, the consensus is that vitamin D has a host of immunomodulatory effects which may be beneficial in the context of COVID-19 and that low levels of vitamin D can result in dysfunction of crucial antimicrobial effects, potentially contributing to poor prognosis. Studies also show that the effects of low vitamin D can be mitigated via supplementation, although the benefits of vitamin D supplementation in the treatment of COVID-19 remain controversial.

Clinical and laboratory findings of COVID-19: A systematic review and meta-analysis

BACKGROUND/PURPOSE

The aim of this study was to systematically review all COVID-19 publications to summarize the clinical features, assess comorbidities, prevalence, and disease outcomes.

METHODS

Included were all COVID-19 published studies between January 1 to July 20, 2020. The random effect model was used to calculate the pooled prevalence and corresponding 95% confidence interval (CI). Publication bias was assessed using the funnel plot for the standard error by logit event.

RESULTS

The mean age of the patients was 46.8 years (95% CI, 41.0-52.6) and males comprised 54.0% (95% CI, 51.3-56.7). Total co-morbidities prevalence was 29.5% (95% CI, 19.0-36.6), with diabetes mellitus being the most prevalent 13.8% (95% CI, 8.7-21.1), followed by hypertension 11.7% (95% CI, 5.7-22.6), and cardiovascular disease 9.7% (95% CI, 6.5-14.2). The most common clinical manifestations were fever, 82.0% (95% CI, 67.7-90.8), cough 54.3% (95% CI, 45.5-62.9), fatigue 30.2% (95% CI, 23.3-38.1), sputum 28.5% (95% CI, 21.2-37.2), sore throat 21.7% (95% CI, 14.6-31.0), and headache 11.0% (95% CI, 7.9-15.2). The most common COVID-19 serious complications were RNA Anemia 98.2% (95% CI, 96.2-99.2), hospitalization 83.7% (95% CI, 76.0-89.3), bilateral pneumonia 70.9% (95% CI, 58.2-81.0); of those hospitalized 43.5% (95% CI, 24.9-64.2) were discharged. Fatality accounted for 10.5% (95% CI 6.8-16.1).

CONCLUSION

Patients infected with COVID-19 coronavirus showed a wide range of clinical presentation with non-specific symptoms.

Key Considerations for the Development of Safe and Effective SARS-CoV-2 Subunit Vaccine: A Peptide-Based Vaccine Alternative

COVID-19 is disastrous to global health and the economy. SARS-CoV-2 infection exhibits similar clinical symptoms and immunopathological sequelae to SARS-CoV infection. Therefore, much of the developmental progress on SARS-CoV vaccines can be utilized for the development of SARS-CoV-2 vaccines. Careful antigen selection during development is always of utmost importance for the production of effective vaccines that do not compromise recipient safety. This holds especially true for SARS-CoV vaccines, as several immunopathological disorders are associated with the activity of structural and nonstructural proteins encoded in the virus's genetic material. Whole viral protein and RNA-encoding full-length proteins contain both protective and "dangerous" sequences, unless pathological fragments are deleted. In light of recent advances, peptide vaccines may present a very safe and effective alternative. Peptide vaccines can avoid immunopathological pro-inflammatory sequences, focus immune responses on neutralizing immunogenic epitopes, avoid off-target antigen loss, combine antigens with different protective roles or mechanisms, even from different viral proteins, and avoid mutant escape by employing highly conserved cryptic epitopes. In this review, an attempt is made to exploit the similarities between SARS-CoV and SARS-CoV-2 in vaccine antigen screening, with particular attention to the pathological and immunogenic properties of SARS proteins.

Clinical-Pathological Correlation of the Pathophysiology and Mechanism of Action of COVID-19 - a Primer for Clinicians

PURPOSE OF REVIEW

Increasing knowledge of the pathogenesis of the SARS-CoV-2 infection and the complex interaction between host and viral factors have allowed clinicians to stratify the severity of COVID-19 infection. Epidemiological data has also helped to model viral carriage and infectivity. This review presents a comprehensive summary of the pathophysiology of COVID-19, the mechanisms of action of the SARS-CoV-2 virus, and the correlation with the clinical and biochemical characteristics of the disease.

RECENT FINDINGS

ACE2 and TMPRSS2 receptors have emerged as a key player in the mechanism of infection of SARS-CoV-2. Their distribution throughout the body has been shown to impact the organ-specific manifestations of COVID-19. The immune-evasive and subsequently immunoregulative properties of SARS-CoV-2 are also shown to be implicated in disease proliferation and progression. Information gleaned from the virological properties of SARS-CoV-2 is consistent with and reflects the clinical behavior of the COVID-19 infection. Further study of specific clinical phenotypes and severity classes of COVID-19 may assist in the development of targeted therapeutics to halt progression of disease from mild to moderate-severe. As the understanding of the pathophysiology and mechanism of action of SARS-CoV-2 continues to grow, it is our hope that better and more effective treatment options continue to emerge.

Dynamic changes of functional fitness, antibodies to SARS-CoV-2 and immunological indicators within 1 year after discharge in Chinese health care workers with severe COVID-19: a cohort study

BACKGROUND

Few studies had described the health consequences of patients with coronavirus disease 2019 (COVID-19) especially in those with severe infections after discharge from hospital. Moreover, no research had reported the health consequences in health care workers (HCWs) with COVID-19 after discharge. We aimed to investigate the health consequences in HCWs with severe COVID-19 after discharge from hospital in Hubei Province, China.

METHODS

We conducted an ambidirectional cohort study in "Rehabilitation Care Project for Medical Staff Infected with COVID-19" in China. The participants were asked to complete three physical examinations (including the tests of functional fitness, antibodies to SARS-CoV-2 and immunological indicators) at 153.4 (143.3, 164.8), 244.3 (232.4, 259.1), and 329.4 (319.4, 339.3) days after discharge, respectively. Mann-Whitney U test, Kruskal-Wallis test, t test, one-way ANOVA, χ², and Fisher's exact test were used to assess the variance between two or more groups where appropriate.

RESULTS

Of 333 HCWs with severe COVID-19, the HCWs' median age was 36.0 (31.0, 43.0) years, 257 (77%) were female, and 191 (57%) were nurses. Our research found that 70.4% (114/162), 48.9% (67/137), and 29.6% (37/125) of the HCWs with severe COVID-19 were considered to have not recovered their functional fitness in the first, second, and third functional fitness tests, respectively. The HCWs showed improvement in muscle strength, flexibility, and agility/dynamic balance after discharge in follow-up visits. The seropositivity of IgM (17.0% vs. 6.6%) and median titres of IgM (3.0 vs. 1.4) and IgG (60.3 vs. 45.3) in the third physical examination was higher than that in the first physical examination. In the third physical examination, there still were 42.1% and 45.9% of the HCWs had elevated levels of IL-6 and TNF-α, and 11.9% and 6.3% of the HCWs had decreased relative numbers of CD3⁺ T cells and CD4⁺ T cells.

CONCLUSION

The HCWs with severe COVID-19 showed improvement in functional fitness within 1 year after discharge, active intervention should be applied to help their recovery if necessary. It is of vital significance to continue monitoring the functional fitness, antibodies to SARS-CoV-2 and immunological indicators after 1 year of discharge from hospital in HCWs with severe COVID-19.

Lymphocytes screening on admission is essential for predicting in-hospital clinical outcome in COVID-19 patients: A retrospective cohort study

Introduction

We aimed to identify the associations between the lymphocytes (LYM) absolute count on admission and clinical outcomes in COVID‐19 patients.

Methods

In this retrospective study, 224 COVID‐19 patients who were admitted to General Hospital of Central Theater Command of the PLA from January 22 to April 4, 2020, were consecutively included. These patients were divided into the lymphopenia group and the nonlymphopenia group according to whether the LYM count on admission was below the normal range.

Results

During hospitalization, patients in the lymphopenia group have a much higher all‐cause mortality (14.5% vs 0.0%; P < .001) and an evidently longer length of hospital stay (24.0 vs 17.5 days; P < .001) than patients in the nonlymphopenia group. The correlation analysis results indicated that the LYM count was negatively correlated with the values of NEU (R = −.2886, P < .001), PT (R = −.2312, P < .001), FIB (R = −.2954, P < .001), D‐D (R = −.3554, P < .001), CRP (R = −.4899, P < .001), IL‐6 (R = −.5459, P < .001), AST (R = −.2044, P < .01), Cr (R = −.1350, P < .05), CPK (R = −.2119, P < .01), CK‐Mb (R = −.1760, P < .01), and LDH (R = −.4330, P < .001), and was positively correlated with the count of PLT (R = .2679, P < .001). In addition, LYM as a continuous variable was associated with 97% decreased risk of in‐hospital mortality in the fully adjusted models (OR = 0.03, 95%CI, 0.00‐0.37, P < .001).

Discussion

LYM screening on admission is a critical predictor for assessment of disease severity and clinical outcomes in patients with COVID‐19, and lymphopenia substantially correlates with poor clinical outcomes.

Glycophosphopeptical AM3 Food Supplement: A Potential Adjuvant in the Treatment and Vaccination of SARS-CoV-2

The world is currently experiencing the coronavirus disease 2019 (COVID-19) pandemic caused by Severe Acute Respiratory Syndrome-2 (SARS-CoV-2). Its global spread has resulted in millions of confirmed infections and deaths. While the global pandemic continues to grow, the availability of drugs to treat COVID-19 infections remains limited to supportive treatments. Moreover, the current speed of vaccination campaigns in many countries has been slow. Natural substrates with biological immunomodulatory activity, such as glucans, may represent an adjuvant therapeutic agent to treat SARS-CoV-2. AM3, a natural glycophosphopeptical, has previously been shown to effectively slow, with no side effects, the progression of infectious respiratory diseases by regulating effects on innate and adaptive immunity in experimental models. No clinical studies, however, exist on the use of AM3 in SARS-CoV-2 infected patients. This review aims to summarize the beneficial effects of AM3 on respiratory diseases, the inflammatory response, modulation of immune response, and attenuation of muscle. It will also discuss its potential effects as an immune system adjuvant for the treatment of COVID-19 infections and adjuvant for SARS-CoV-2 vaccination.

Clinical and Hematological Characteristics of Patients with COVID-19 Co-infected with Bacteria

Background: The pandemic caused by the new coronavirus is overwhelming the world. Bacteria and fungi were detected in some cases, which suggested the associations between COVID-19 and bacterial and fungal infections. Objectives: To provide suggestions and treatment opinions by analyzing laboratory data of COVID-19 patients co-infected with bacteria. Methods: We analyzed 63 patients with COVID-19 admitted to the isolation ward of the First Affiliated Hospital of Wenzhou Medical University. COVID-19 was detected using PCR, and bacteria were identified using culture. Patients were divided into two groups, including those with and those without bacterial infections, and differences in hematologic indices between the groups were analyzed. Results: There were 63 patients with median age of 55.82 years. The average hospital stay was 22.56 days. Seven patients (11.11%) had coincident bacterial infections. Detection rates in sputum/alveolar lavage and blood were the highest, 60.52% and 21.05%, respectively. Klebsiella pneumoniae, Acinetobacter, and Stenotrophomonas maltophilia were the most common found in 31.58%, 18.42%, and 15.79%, respectively. Interleukin 6 (IL-6) levels were elevated in 84.13% of patients, while IL-10 levels were elevated in 69.84%, blood ammonia levels were elevated in 82.05%, lactate levels were elevated in 75.41%, and LDH levels were elevated in 69.84%. There were significant differences between the groups in terms of expression levels of IgG, C4, AST, LDH, IL-6, IL-10, percentage of neutrophils, percentage of lymphocytes, and platelets. Conclusions: For patients with COVID-19 suspected of having bacterial infections, empiric antibiotics should be given to cover K. pneumoniae, Acinetobacter, and S. maltophilia.

Mathematical Model of Antiviral Immune Response against the COVID-19 Virus

This work presents a mathematical model to investigate the current outbreak of the coronavirus disease 2019 (COVID-19) worldwide. The model presents the infection dynamics and emphasizes the role of the immune system: both the humoral response as well as the adaptive immune response. We built a mathematical model of delay differential equations describing a simplified view of the mechanism between the COVID-19 virus infection and the immune system. We conduct an analysis of the model exploring different scenarios, and our numerical results indicate that some theoretical immunotherapies are successful in eradicating the COVID-19 virus.

Insight into the LFA-1/SARS-CoV-2 Orf7a Complex by Protein-Protein Docking, Molecular Dynamics, and MM-GBSA Calculations

In the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) genome, open reading frames (ORFs) encode for viral accessory proteins. Among these, Orf7a structurally resembles the members of the immunoglobulin (Ig) superfamily and intracellular adhesion molecules (ICAMs), in particular. ICAMs are involved in integrin binding through lymphocyte function-associated antigen 1 (LFA-1). Based on such considerations and on previous findings on SARS-CoV, it has been postulated that the formation of the LFA-1/Orf7a complex could contribute to SARS-CoV-2 infectivity and pathogenicity. With the current work, we aim at providing insight into this macromolecular assembly, taking advantage of the recently reported SARS-CoV-2 Orf7a structure. Protein-protein docking, molecular dynamics (MD) simulations, and a Molecular Mechanical-Generalized Born Surface Area (MM-GBSA)-based stage were enrolled to provide refined models.

Severe acute respiratory syndrome coronavirus 2 for physicians: Molecular characteristics and host immunity (Review)

Recently, severe acute respiratory syndrome (SARS) coronavirus (CoV) 2 (SARS‑CoV‑2)‑causing CoV disease 2019 (COVID‑19) emerged in China and has become a global pandemic. SARS‑CoV‑2 is a novel CoV originating from β‑CoVs. Major distinctions in the gene sequences between SARS‑CoV and SARS‑CoV‑2 include the spike gene, open reading frame (ORF) 3b and ORF 8. SARS‑CoV‑2 infection is initiated when the virus interacts with angiotensin‑converting enzyme 2 (ACE2) receptors on host cells. Through this mechanism, the virus infects the alveolar, esophageal epithelial, ileum, colon and other cells on which ACE2 is highly expressed, causing damage to target organs. To date, host innate immunity may be the only identified direct factor associated with viral replication. However, increased ACE2 expression may upregulate the viral load indirectly by increasing the baseline level of infectious virus particles. The peak viral load of SARS‑CoV‑2 is estimated to occur ~10 days following fever onset, causing patients in the acute stage to be the primary infection source. However, patients in the recovery stage or with occult infections can also be contagious. The host immune response in patients with COVID‑19 remains to be elucidated. By studying other SARS and Middle East respiratory syndrome coronaviruses, it is hypothesized that patients with COVID‑19 may lack sufficient antiviral T‑cell responses, which consequently present with innate immune response disorders. This may to a certain degree explain why this type of CoV triggers severe inflammatory responses and immune damage and its associated complications.

COVID-19: Immunology, Immunopathogenesis and Potential Therapies

The Coronavirus Disease-2019 (COVID-19) imposed public health emergency and affected millions of people around the globe. As of January 2021, 100 million confirmed cases of COVID-19 along with more than 2 million deaths were reported worldwide. SARS-CoV-2 infection causes excessive production of pro-inflammatory cytokines thereby leading to the development of "Cytokine Storm Syndrome." This condition results in uncontrollable inflammation that further imposes multiple-organ-failure eventually leading to death. SARS-CoV-2 induces unrestrained innate immune response and impairs adaptive immune responses thereby causing tissue damage. Thus, understanding the foremost features and evolution of innate and adaptive immunity to SARS-CoV-2 is crucial in anticipating COVID-19 outcomes and in developing effective strategies to control the viral spread. In the present review, we exhaustively discuss the sequential key immunological events that occur during SARS-CoV-2 infection and are involved in the immunopathogenesis of COVID-19. In addition to this, we also highlight various therapeutic options already in use such as immunosuppressive drugs, plasma therapy and intravenous immunoglobulins along with various novel potent therapeutic options that should be considered in managing COVID-19 infection such as traditional medicines and probiotics.

Immunopathological Changes in SARS-CoV-2 Critical and Non-critical Pneumonia Patients: A Systematic Review to Determine the Cause of Co-infection

The ongoing COVID-19 pandemic originating from Wuhan, China is causing major fatalities across the world. Viral pneumonia is commonly observed in COVID-19 pandemic. The number of deaths caused by viral pneumonia is mainly due to secondary bacterial or fungal infection. The immunopathology of SARS-CoV-2 viral pneumonia is poorly understood with reference to human clinical data collected from patients infected by virus and secondary bacterial or fungal infection occurring simultaneously. The co-infection inside the lungs caused by pneumonia has direct impact on the changing lymphocyte and neutrophil counts. Understanding the attribution of these two immunological cells triggered by cytokines level change is of great importance to identify the progression of pneumonia from non-severe to severe state in hospitalized patients. This review elaborates the cytokines imbalance observed in SARS-CoV-1 (2003 epidemic), SARS-CoV-2 (2019 pandemic) viral pneumonia and community acquired pneumonia (CAP), respectively, in patients to determine the potential reason of co-infection. In this review the epidemiology, virology, clinical symptoms, and immunopathology of SARS-CoV-2 pneumonia are narrated. The immune activation during SARS-CoV-1 pneumonia, bacterial, and fungal pneumonia is discussed. Here it is further analyzed with the available literatures to predict the potential internal medicines, prognosis and monitoring suggesting better treatment strategy for SARS-CoV-2 pneumonia patients.

Clinical features and risk factors for severe-critically ill COVID-19 adult patients in Jiangsu, China: A multiple-centered, retrospective study

Coronavirus disease 2019 (COVID-19) becomes a global pandemic in 2020. Early identification of severe ill patients is a top priority for clinicians. We aimed to describe clinical features and risk factors of severe-critically ill patients with COVID-19 in Jiangsu Province.This multi-centered retrospective study collected the information of 631 laboratory-confirmed COVID-19 patients hospitalized at 28 authorized hospitals in Jiangsu province from January 23, 2019 to March 13, 2020.A total of 583 adult patients with laboratory-confirmed COVID-19 were enrolled for final analysis, including 84 severe-critically ill patients and 499 mild-moderate patients. Median age of the severe-critically ill patients was 57.0 years old (interquartile range, 49.0-65.8), and 50 (59.5%) were males. Multisystemic laboratory abnormalities were observed on admission for severe-critically ill patients. These patients showed more noticeable radiologic abnormalities and more coexisting health issues as compared to the mild-moderate patients. Most of the severe-critically ill COVID-19 patients became deteriorated in 2 weeks after diagnosis. Age, D-dimer, and lymphocytes were independently associated with the progression of severe-critically illness.Older age, higher D-dimer levels and less lymphocyte counts on admission are potential risk factors for COVID-19 patients to develop into severe and critically illness.

Is lymphopenia different between SARS and COVID-19 patients?

Lymphopenia is commonly observed in SARS and COVID-19 patients although the lymphocyte count is not always below 0.8 × 109 /L in all the patients. It is suggested that lymphopenia serves as a useful predictor for prognosis in the patients. It is also hypothesized that lymphopenia is related to glucocorticoids and apoptosis. However, the ordering between lymphopenia and apoptosis appears different between SARS and COVID-19 patients, ie, lymphopenia is prior to apoptosis in SARS patients whereas apoptosis is prior to lymphopenia in COVID-19 patients. This paper attempts to figure out this contradiction through three players, lymphopenia, glucocorticoids, and apoptosis. Although the literature does not provide a solid explanation, the level of glucocorticoids could determine the ordering between lymphopenia and apoptosis because the administration of high doses of glucocorticoids could lead to lymphopenia whereas low doses of glucocorticoids could benefit patients. In the meantime, this paper raises several questions, which need to be answered in order to better understand the whole course of COVID-19.

Deregulated cellular circuits driving immunoglobulins and complement consumption associate with the severity of COVID-19 patients

SARS‐CoV‐2 infection causes an abrupt response by the host immune system, which is largely responsible for the outcome of COVID‐19. We investigated whether the specific immune responses in the peripheral blood of 276 patients were associated with the severity and progression of COVID‐19. At admission, dramatic lymphopenia of T, B, and NK cells is associated with severity. Conversely, the proportion of B cells, plasmablasts, circulating follicular helper T cells (cTfh) and CD56^–CD16⁺ NK‐cells increased. Regarding humoral immunity, levels of IgM, IgA, and IgG were unaffected, but when degrees of severity were considered, IgG was lower in severe patients. Compared to healthy donors, complement C3 and C4 protein levels were higher in mild and moderate, but not in severe patients, while the activation peptide of C5 (C5a) increased from the admission in every patient, regardless of their severity. Moreover, total IgG, the IgG1 and IgG3 isotypes, and C4 decreased from day 0 to day 10 in patients who were hospitalized for more than two weeks, but not in patients who were discharged earlier. Our study provides important clues to understand the immune response observed in COVID‐19 patients, associating severity with an imbalanced humoral response, and identifying new targets for therapeutic intervention.

COVID-19 Vaccine: Critical Questions with Complicated Answers

COVID-19 has caused extensive human casualties with significant economic impacts around the globe, and has imposed new challenges on health systems worldwide. Over the past decade, SARS, Ebola, and Zika also led to significant concerns among the scientific community. Interestingly, the SARS and Zika epidemics ended before vaccine development; however, the scholarly community and the pharmaceutical companies responded very quickly at that time. Similarly, when the genetic sequence of SARSCoV-2 was revealed, global vaccine companies and scientists have stepped forward to develop a vaccine, triggering a race toward vaccine development that the whole world is relying on. Similarly, an effective and safe vaccine could play a pivotal role in eradicating COVID-19. However, few important questions regarding SARS-CoV-2 vaccine development are explored in this review.

The role of NK cells in fighting the virus infection and sepsis

Natural killer cells, one of the important types of innate immune cells, play a pivotal role in the antiviral process in vivo. It has been shown that increasing NK cell activity may promote the alleviation of viral infections, even severe infection-induced sepsis. Given the current state of the novel coronavirus (SARS-CoV-2) global pandemic, clarifying the anti-viral function of NK cells would be helpful for revealing the mechanism of host immune responses and decipher the progression of COVID-19 and providing important clues for combating this pandemic. In this review, we summarize the roles of NK cells in viral infection and sepsis as well as the potential possibilities of NK cell-based immunotherapy for treating COVID-19.

Serum-soluble ST2 as a novel biomarker reflecting inflammatory status and illness severity in patients with COVID-19

Aim: The authors studied the role of soluble ST2 (sST2) in COVID-19 and its relationship with inflammatory status and disease severity. Materials & methods: Serum levels of sST2 and interleukin (IL)-33, C-reactive protein (CRP), serum amyloid protein (SAA), IL-6 and procalcitonin (PCT), and T lymphocyte subsets from 80 subjects diagnosed with COVID-19 including 36 mild, 41 severe and three asymptomatic cases were tested. Results: Serum sST2 levels were significantly increased in COVID-19 patients, which were positively correlated with CRP, but negatively correlated with CD4⁺ and CD8⁺ T lymphocyte counts. Serum sST2 levels in nonsurviving severe cases were persistently high during disease progression. Conclusion: Serum sST2 level test is helpful for reflecting inflammatory status and illness severity of COVID-19.

The clinical value of two combination regimens in the Management of Patients Suffering from Covid-19 pneumonia: a single centered, retrospective, observational study

BACKGROUND

There is no identified pharmacological therapy for COVID-19 patients, where potential therapeutic strategies are underway to determine effective therapy under such unprecedented pandemic. Therefore, combination therapies may have the potential of alleviating the patient's outcome. This study aimed at comparing the efficacy of two different combination regimens in improving outcomes of patients infected by novel coronavirus (COVID-19).

METHODS

This is a single centered, retrospective, observational study of 60 laboratory-confirmed COVID-19 positive inpatients (≥18 years old) at two wards of the Baqiyatallah Hospital, Tehran, Iran. Patient's data including clinical and laboratory parameters were recorded. According to the drug regimen, the patients were divided into two groups; group I who received regimen I consisting azithromycin, prednisolone, naproxen, and lopinavir/ritonavir and group II who received regimen II including meropenem, levofloxacin, vancomycin, hydroxychloroquine, and oseltamivir.

RESULTS

The oxygen saturation (SpO2) and temperature were positively changed in patients receiving regimen I compared to regimen II (P = 0.013 and P = 0.012, respectively). The serum level of C-reactive protein (CRP) changed positively in group I (P < 0.001). Although there was a significant difference in platelets between both groups (75.44 vs 51.62, P < 0.001), their change did not clinically differ between two groups. The findings indicated a significant difference of the average length of stay in hospitals (ALOS) between two groups, where the patients under regimen I showed a shorter ALOS (6.97 vs 9.93, P = 0.001).

CONCLUSION

This study revealed the beneficial effect of the short-term use of low-dose prednisolone in combination with azithromycin, naproxen and lopinavir/ritonavir (regimen I), in decreasing ALOS compared to regimen II. Since there is still lack of evidence for safety of this regimen, further investigation in our ongoing follow-up to deal with COVID-19 pneumonia is underway. Graphical abstract.

Assessing SARS-CoV-2 RNA levels and lymphocyte/T cell counts in COVID-19 patients revealed initial immune status as a major determinant of disease severity

The magnitude of SARS-CoV-2 infection, the dynamic changes of immune parameters in patients with the novel coronavirus disease (COVID-19) and their correlation with the disease severity remain unclear. The clinical and laboratory results from 154 confirmed COVID-19 patients were collected. The SARS-CoV-2 RNA levels in patients were estimated using the Ct values of specific RT-PCR tests. The lymphocyte subsets and cytokine profiles in the peripheral blood were analyzed by flow cytometry and specific immunoassays. 154 confirmed COVID-19 patients were clinically examined up to 4 weeks after admission. The initial SARS-CoV-2 RNA Ct values at admission varied, but were comparable in the patient groups classified according to the age, gender, underlying diseases, and disease severity. Three days after admission, significant higher Ct values were found in severe cases. Significantly reduced counts of T cells and T cell subsets were found in patients with old age and underlying diseases at admission and were characteristic for the development of severe COVID-19. Severe COVID-19 developed preferentially in patients with underlying compromised immunity and was not associated with initial virus levels. Higher SARS-CoV-2 RNA levels in severe cases were apparently a result of impaired immune control associated with dysregulation of inflammation.

Transcriptomic characteristics of bronchoalveolar lavage fluid and peripheral blood mononuclear cells in COVID-19 patients

Circulating in China and 158 other countries and areas, the ongoing COVID-19 outbreak has caused devastating mortality and posed a great threat to public health. However, efforts to identify effectively supportive therapeutic drugs and treatments has been hampered by our limited understanding of host immune response for this fatal disease. To characterize the transcriptional signatures of host inflammatory response to SARS-CoV-2 (HCoV-19) infection, we carried out transcriptome sequencing of the RNAs isolated from the bronchoalveolar lavage fluid (BALF) and peripheral blood mononuclear cells (PBMC) specimens of COVID-19 patients. Our results reveal distinct host inflammatory cytokine profiles to SARS-CoV-2 infection in patients, and highlight the association between COVID-19 pathogenesis and excessive cytokine release such as CCL2/MCP-1, CXCL10/IP-10, CCL3/MIP-1A, and CCL4/MIP1B. Furthermore, SARS-CoV-2 induced activation of apoptosis and P53 signalling pathway in lymphocytes may be the cause of patients' lymphopenia. The transcriptome dataset of COVID-19 patients would be a valuable resource for clinical guidance on anti-inflammatory medication and understanding the molecular mechansims of host response.

Neurotropism of SARS-CoV-2 and its neuropathological alterations: Similarities with other coronaviruses

A novel coronavirus (SARS-CoV-2) emerged from Wuhan, China, and spread quickly around the world. In addition to fever, cough and shortness of breath, it was confirmed that the patients also have manifestations towards the central nervous system (CNS), especially those critically ill ones. In this review, we will discuss how SARS-CoV-2 gain access to the CNS and the possible consequences. Both SARS-CoV-2 and SARS-CoV-1 in 2002 share the same receptor angiotensin-converting enzyme 2 (ACE2), which can be found in the brain and mediate the disease process. Both direct attack of SARS-CoV-2 and the abnormal immune response in the CNS would contribute to the disease. Also, there is a relationship between SARS-CoV-2 and the occurrence of acute cerebrovascular diseases.

Estimating the release of inflammatory factors and use of glucocorticoid therapy for COVID-19 patients with comorbidities

COVID-19 exhibits both variability and rapid progression, particularly in patients with comorbidities such as diabetes, hypertension or cancer. To determine how these underlying disorders exacerbate pneumonia in COVID-19, we evaluated 79 patients with severe COVID-19 and grouped them according to whether or not they had comorbidities. Clinical information, laboratory examinations, immunological function, and treatment outcomes were retrospectively analyzed. Our study revealed that severe COVID-19 patients with comorbidities had higher levels of inflammatory indices, including blood interferon-γ, interleukin (IL)-6 and c-reactive protein levels as well as the erythrocyte sedimentation rate. These were accompanied by lymphopenia, hypokalemia, hypoalbuminemia, a decrease in either CD4+ T cells or lymphocyte count, and coagulation disorders, which were closely related to poor prognosis. Patients with comorbidities also had longer disease remission times (27 ± 6.7 days) than those without comorbidities (20 ± 6.5 days). Cox multivariate analysis indicated that glucocorticoid therapy and IL-6 were independent prognostic factors. Our findings suggest that coexisting comorbidities aggravate COVID-19 through the excessive release of inflammatory factors and that glucocorticoid therapy may be beneficial.

Physical Exercise as a Multimodal Tool for COVID-19: Could It Be Used as a Preventive Strategy?

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) or coronavirus disease 2019 (COVID-19) is a novel coronavirus not previously recognized in humans until late 2019. On 31 December 2019, a cluster of cases of pneumonia of unspecified etiology was reported to the World Health Organization in China. The availability of adequate SARS-CoV-2 drugs is also limited, and the efficacy and safety of these drugs for COVID-2019 pneumonia patients need to be assessed by further clinical trials. For these reasons, there is a need for other strategies against COVID-19 that are capable of prevention and treatment. Physical exercise has proven to be an effective therapy for most chronic diseases and microbial infections with preventive/therapeutic benefits, considering that exercise involves primary immunological mediators and/or anti-inflammatory properties. This review aimed to provide an insight into how the implementation of a physical exercise program against COVID-19 may be a useful complementary tool for prevention, which can also enhance recovery, improve quality of life, and provide immune protection against SARS-CoV-2 virus infection in the long term. In summary, physical exercise training exerts immunomodulatory effects, controls the viral gateway, modulates inflammation, stimulates nitric oxide synthesis pathways, and establishes control over oxidative stress.

Primer on the Pathogenesis of Severe COVID-19: Part One

In Part One of this exploration of the pathogenesis of coronavirus disease (COVID-19), the author will evaluate the viral and cellular immunological basis for the condition. The virus demonstrates a remarkable capability not just to evade, but to exploit host immune characteristics to perpetuate viral replication. In this regard, severe acute respiratory syndrome (SARS)/severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) disables most antiviral mechanisms, including the early interferon response, and avoids detection to permit unimpeded viral multiplication. Consequently, antigen-presenting cells fail to adequately stimulate the T-cell receptor. As a consequence, T-cell p53 remains highly expressed, which in turn disables an adequate effector T-cell response. Replicating SARS-CoV-2 double-strand RNA robustly activates protein kinase R (PKR)/PKR-like endoplasmic reticulum kinase (PERK). While the virus is grossly invulnerable to its antiviral effects, PKR is crucial for effecting the cytokine milieu in COVID-19. PERK is a component of the unfolded protein response, which eventuates in autophagy. SARS virions use double-membrane vesicles and adapt PERK signalling not only to avoid autophagy, but to facilitate replication. Viral activation of PKR/PERK is mutually exclusive to NLRP3 stimulation. The NLRP3 pathway elaborates IL-1β. This is chiefly a feature of paediatric SARS/SARS-CoV-2 cases. The difficulties encountered in predicting outcome and forging effective therapeutics speaks to the breadth of complexity of the immunopathogenesis of this virus.

Biochemical and immunological aspects of COVID-19 infection and therapeutical intervention of oral low dose cytokine therapy: a systematic review

The novel coronavirus (SARS-CoV-2) pandemic has now spread to all corners of the world. It causes severe respiratory syndromes which is one of the leading causes of death. Evidence shows that the novel SARS-CoV-2 has close similarities with other coronaviruses, SARS and MERS. So, SARS-CoV-2 might use the similar mechanisms of these viruses to attack the host cells. The severity of COVID-19 is associated with various factors, one of the major reasons is immune dysregulation or immune suppression. Immunity plays a significant role in maintaining the body in a healthy condition. In order to induce a timely immune response against the invaded pathogens, both innate and adaptive immunity must be in an active state. During the viral infection, there will be an excessive generation of pro-inflammatory cytokines known as cytokine storm and also, the antiviral agents in the body gets inhibited or inactivated through viral mechanisms. Thus, this might be the reason for the transition from mild symptoms to more severe medical conditions which leads to an immediate need for the invention of a new medicine.This review aims to show the host-viral interaction along with immune response, antiviral mechanism and effectiveness of oral low dose cytokines against the virus as a therapeutic approach.

Immunomodulation for Severe COVID-19 Pneumonia: The State of the Art

COVID-19 has become a worldwide pandemic caused by the novel coronavirus named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Severe cases of COVID-19 have accounted for 10-20% of all infections, leading to more than 500,000 deaths. Increasing evidence has suggested that the inflammatory cytokine storm originating from the anti-SARS-CoV-2 immune response plays an important role in the pathogenesis of critically ill patients with COVID-19, which leads to mixed antagonistic response syndrome (MARS). In the early stage of severe COVID-19, systemic inflammatory response syndrome causes acute respiratory distress syndrome, multiple organ dysfunction syndrome, and even multiple organ failure. In the late stage of severe disease, increased production of anti-inflammatory cytokines drives the immune response to become dominated by compensatory anti-inflammatory response syndrome, which leads to immune exhaustion and susceptibility to secondary infections. Therefore, precise immunomodulation will be beneficial for patients with severe COVID-19, and immunosuppressive or immune enhancement therapy will depend on the disease course and immune status. This review summarizes the current understanding of the immunopathogenesis of severe COVID-19, especially the role of the inflammatory cytokine storm in disease progression. Immune indicators and immunotherapy strategies for severe COVID-19 are reviewed and the potential implications discussed.

Recent advances in vaccine and immunotherapy for COVID-19

The COVID-19 pandemic caused by SARS-CoV-2 has resulted in millions of cases and hundreds of thousands of deaths. Beyond there being no available antiviral therapy, stimulating protective immunity by vaccines is the best option for managing future infections. Development of a vaccine for a novel virus is a challenging effort that may take several years to accomplish. This mini-review summarizes the immunopathological responses to SARS-CoV-2 infection and discusses advances in the development of vaccines and immunotherapeutics for COVID-19.

Immune response in COVID-19: What do we currently know?

In 2002/2003 there was a pandemic denominate SARS (severe acute respiratory syndrome), caused by the SARS-CoV virus that belongs to the genera Betacoranavirus and the family Coronaviridae, generally responsible for influenza infections. In mid of 2019, a new disease by the coronavirus named by COVID-19 (SARS-CoV-2) emerged, both infections have flu symptoms, however they are infections that variable intensity, being medium to severe. In medium infections individuals have the virus and exhibit symptoms, however hospitalization is not necessary, in severe infections, individuals are hospitalized, have high pathology and in some cases progress to death. The virus is formed by simple positive RNA, enveloped, non-segmented, and presenting the largest genome of viruses constituting 32 Kb, consisting of envelope proteins, membrane, nucleocapsid and spike protein, which is essential in the interaction with the host cells. As for the origin of this virus, research has been intensified to determine this paradox and although the similarity with SARS-CoV, this virus did not has necessarily the same place of origin. As for the immune system, it is currently unknown how this new virus interacts. In this brief review, we demonstrate important considerations about the responses to this infection.