Controversial role of neutrophilic granulocytes in the immunopathogenesis of COVID-19: correlation with imbalance of pro-inflammatory neutrophil-associated cytokines and interferon alpha deficiency.

Neutrophilic granulocytes (NG) are the main drivers of pathological inflammation in COVID-19. Objective. To specify the mechanisms of immunopathogenesis of COVID-19 based on a comparative immunological study of the number and phenotype of CD16+SD62L+CD11b+CD63- and CD16+SD62L+CD11b+CD63+ subsets with an assessment of their effector functions against changing profile of NG-associated cytokines IL-8, IL-18, IL-17A, VEGF-A, IFNalpha, and IFNgamma. Patients and methods. In patients with moderate-to-severe and severe COVID-19, we determined IL-1beta, TNFalpha, IL-6, IL-8, IL-18, IL-17A, VEGF-A, IFNalpha, and IFNgamma (ELISA), the phenotype of CD16+SD62L+CD11b+CD63- and CD16+SD62L+CD11b+CD63+ subsets, NF-kappaB-NG (CYTOMICS FC500), phagocytically active NG (%), neutrophil extracellular traps (NETs), NG in apoptosis, and the activity of NADPH oxidase. Results. In COVID-19 against the background of IFNalpha and IFNgamma production blockade and high levels of NG-associated IL-8, IL-18, IL-17A, VEGF-A, a reduction in the number of mature and functionally active CD16brightSD62LbrightCD11bbrightCD63-NG subsets was revealed, as well as an increase in the number of CD16dimSD62LdimSD11bbrightCD63-NG subsets with an immunosuppressive phenotype and CD16brightSD62LbrightSD11bbrightCD63bright-NG subsets with high cytotoxic activity and ability to form NETs, a decrease in the percentage of phagocytically active NG and an increase in the activity of NADPH oxidase, NETs, and NG in apoptosis. Conclusion. IFNalpha deficiency provokes a hyperergic response of NG-associated cytokines, which leads to the formation of uncontrolled immune inflammation involving NG subsets with an immunosuppressive and cytotoxic phenotype, exacerbating the course of COVID-19. The use of recombinant IFNalpha-2b with antioxidants (Viferon) in the early stages of the disease can help to restore immune homeostasis, normalize the level of NG-associated cytokines, reduce NERTs, and achieve good clinical efficacy.Copyright © 2022, Dynasty Publishing House. All rights reserved.

CD40.SARS.CoV2 VACCINE, BUT NOT mRNA, INDUCES SPECIFIC CD8+ T MEMORY STEM CELLS

Background: Vaccination plays a major role in controlling SARS-CoV2 infection but faces the issue of short-term protection. Beyond the generation of Abs, induction of memory CD8+T cells with stem cell-like (Tscm) properties is essential for long-term immunity to viruses. We have designed a sub-unit CD40.CoV-2 vaccine which targets Spike (S) and nucleocapsid (N) regions from SARS-CoV-2 to antigen presenting cells with comparable immunogenicity and protective effect than mRNA BNT162b2 (Pfizer-BioNTech) in preclinical models (Coleon S. EBioMed 2022). We hypothesized that CD40.CoV2 vaccine will elicit CD8+ Tscm cells. Method(s): CD40.CoV2 vaccine is a fully humanized mAb fused to RBD (aa 318-541) and N (aa 276-411). Humanized (hu) NSG mice (HIS-mice) (n=6/ group) received: i) CD40.CoV2 (10 mug equal to 1.3 mug of RBD, i.p.) +/- poly-ICLC (TLR3 agonist;50mug) or ii) BNT162b2 (1mug, i.m.);iii) IgG4.CoV2 (10mug, i.p.) as non-CD40-targeting control. Phenotype and function of splenic S and N-specific T cells were assessed at W5. Result(s): The CD40.CoV2 vaccine +/- poly-CLC induced significant S and N-specific Th1 huCD4+, cytokines-secreting huCD8+ T cells and RBD-specific IgG-switched huB cells as compared to mock injections and non-targeted IgG4.CoV2. CD40.CoV-2 vaccine +/- adjuvant induced higher frequencies of huCD8+ Tscm (CD95+ CD45RA+ CD62L+ ;median, (IQR) 22.4% (12.3-27.4) and 23% (20.7-29.1) +/- adjuvant, respectively) and central memory (TCM;CD45RA- CD62L+) CD8+ T cells (2.7% (2.3-6.2) and 5.1% (3.8-7.8) +/- adjuvant, respectively). In contrast, BNT162b2 induced predominantly effector memory (TEM, CD45RA- CD62L- ;median, (IQR) 63.1% (47.3-72.3)) but not Tscm (1.6% (0.9-6.6)) (figure). CD40.CoV-2 induced huCD8+ Tscm cells exhibit ;i) a higher proliferation index than TCM and TEM;ii) a functional profile secreting TNF and IFNgamma after restimulation with RBD or N peptides;cardinal features of Tscm cells. Conclusion(s): The CD40.SARS.CoV2, but not BNT162b2 vaccine, stimulates selective enrichment in S-and N-specific CD8+ Tscm cells that support longlasting anti-viral immunity. CD40.CoV2 sub-unit is under clinical development as a booster vaccine aimed to maintain durable anti-viral T and humoral responses. (Figure Presented).

IMMUNE SYSTEM PROFILE and CYTOKINE LEVELS of SARS-CoV-2 in PREGNANCY and NEWBORNS

Background: Knowledge about SARS-CoV2 infection in pregnancy and exposed newborns is deficient. We performed a longitudinal analysis of innate immune system status and determined soluble cytokines of women infected with SARS-CoV2 during pregnancy and their newborns Methods: Women with confirmed SARS-CoV2 infection (RT-PCR+ or SARS-CoV2 anti-IgM/IgG+) (COVID MOTHER group, CM n=29, median age of 31 years) and their SARS-CoV2 exposed uninfected newborns were recruited from Hospital Gregorio Marañón, Spain. Peripheral blood mononuclear cells (PBMCs), cord cells and plasma were collected at birth and 6 months later (n=15). The immunophenotyping of innate components (natural killer cells [NK] and monocytes) was studied on cryopreserved PBMCs and cord cells by multiparametric flow cytometry. Up to 4 soluble pro/anti-inflammatory cytokines were assessed in plasma and cord plasma by ELISA assay. CM was compared to a healthy non-SARS-CoV2 infected mothers' group matched by age (SARS-CoV2 PCR-and SARS-CoV2 anti-IgM/IgG-)(Uninfected Mothers, UM n=16) and their newborns (n=16) Results: On NK cell assays, CM show at baseline lower percentage of CD16++ subset, higher NKG2D and lower NKG2A expression on CD16++ and CD56++ subsets and reduced CD57 expression compared to UM;proportion of CD16++ subset and percentage of NKG2D reverted after 6 months(A). Regarding monocytes, CM show increased levels of CD62L and decreased CD49d expression on classical subset, elevated intermediate monocytes proportion and decreased CD40 expression on patrolling subset(B). No differences were found 6 months later. No newborn was infected by SARS-CoV2 and the phenotype analyzed on cord cells shows lower frequency of NK subsets compared with unexposed children and increased CD16++ subset after 6 months(C). In monocytes distribution, exposed children present lower frequency of total monocytes and its subsets than unexposed. Classical monocytes show significant changes at follow-up time-point(D). Increased TNFα and IL10 levels were found on CM compared to UM. Strong and direct correlations were observed between the age and IL6(E). No differences were observed in soluble cytokine levels comparing both groups of newborns Conclusion: SARS-CoV2 infection during pregnancy shows differences in activation, maturation and endothelial markers on innate immune system that could lead newborns clinical implications at birth. However, altered cell proportions and phenotypes found at SARS-CoV2 at birth time and on their exposed newborns is later reverted.

Immune Responses to IAV Infection and the Roles of L-Selectin and ADAM17 in Lymphocyte Homing.

Influenza A virus (IAV) infection is a global public health burden causing up to 650,000 deaths per year. Yearly vaccination programmes and anti-viral drugs currently have limited benefits; therefore, research into IAV is fundamental. Leukocyte trafficking is a crucial process which orchestrates the immune response to infection to protect the host. It involves several homing molecules and receptors on both blood vessels and leukocytes. A key mediator of this process is the transmembrane glycoprotein L-selectin, which binds to vascular addressins on blood vessel endothelial cells. L-selectin classically mediates homing of naïve and central memory lymphocytes to lymph nodes via high endothelial venules (HEVs). Recent studies have found that L-selectin is essential for homing of activated CD8+ T cells to influenza-infected lungs and reduction in virus load. A disintegrin and metalloproteinase 17 (ADAM17) is the primary regulator of cell surface levels of L-selectin. Understanding the mechanisms that regulate these two proteins are central to comprehending recruitment of T cells to sites of IAV infection. This review summarises the immune response to IAV infection in humans and mice and discusses the roles of L-selectin and ADAM17 in T lymphocyte homing during IAV infection.

Immunological insights of selectins in human disease mechanism.

Selectin enzymes are glycoproteins and are an important adhesion molecule in the mammalian immune system, especially in the inflammatory response and the healing process of tissues. Selectins play an important role in a variety of biological processes, including the rolling of leukocytes in endothelial cells, a process known as the adhesion cascade. It has recently been discovered and reported that the selectin mechanism plays a role in cancer and thrombosis disease. This process begins with non-covalent interactions-based selectin-ligand binding and the glycans play a role as a connector between cancer cells and the endothelium in this process. The selectin mechanism is critical for the immune system, but it is also involved in disease mechanisms, earning the selectins the nickname "Selectins-The Two Dr. Jekyll and Mr. Hyde Faces". As a result, the drug for selectins should have a multifaceted role and be a dynamic molecule that targets the disease mechanism specifically. This chapter explores the role of selectins in the disease mechanism at the mechanism level that provides the impact for identifying the selectin inhibitors. Overall, this chapter provides the molecular level insights on selectins, their ligands, involvement in normal and disease mechanisms.

Evaluation of admission levels of P, E and L selectins as predictors for thrombosis in hospitalized COVID-19 patients.

Thromboembolic complications are the most reported cause of death in coronavirus disease-2019 (COVID-19). Hypercoagulability, platelets activation and endotheliopathy are well-recognized features in COVID-19 patients. The aim of this work was to evaluate circulating soluble selectins P, E and L at the time of hospital admission as predictors for upcoming thrombosis. This retrospective study included 103 hospitalized COVID-19 patients and 50 healthy volunteer controls. COVID-19 patients were categorized into two groups; group 1 who developed thrombosis during hospitalization and group 2 who did not. Soluble selectins were quantitated using ELISA technique. Higher levels of sP-selectin, sE-selectin and sL-selectin were detected in COVID-19 patients compared to controls. Furthermore, significantly higher levels were found in group 1 compared to group 2. Their means were [5.86 ± 1.72 ng/mL vs. 2.51 ± 0.81 ng/mL]; [50 ± 8.57 ng/mL vs. 23.96 ± 6.31 ng/mL] and [4.66 ± 0.83 ng/mL vs. 2.95 ± 0.66 ng/mL] for sP-selectin, sE-selectin and sL-selectin respectively. The elevated selectins correlated with the currently used laboratory biomarkers of disease severity. After adjustment of other factors, sP-selectin, sE-selectin and sL-selectin were independent predictors for thrombosis. At sP-selectin ≥ 3.2 ng/mL, sE-selectin ≥ 32.5 ng/mL and sL-selectin ≥ 3.6 ng/mL thrombosis could be predicted with 97.1%, 97.6% and 96.5% sensitivity. A panel of the three selectins provided 100% clinical sensitivity. Admission levels of circulating soluble selectins P, E and L can predict thrombosis in COVID-19 patients and could be used to identify patients who need prophylactic anticoagulants. E-selectin showed a superior clinical performance, as thrombo-inflammation biomarker, to the most commonly studied P-selectin.

An increase in CD62Ldim neutrophils precedes the development of pulmonary embolisms in COVID-19 patients.

OBJECTIVES: A high incidence of pulmonary embolism (PE) is reported in patients with critical coronavirus disease 2019 (COVID-19). Neutrophils may contribute to this through a process referred to as immunothrombosis. The aim of this study was to investigate the occurrence of neutrophil subpopulations in blood preceding the development of COVID-19 associated PE. METHODS: We studied COVID-19 patients admitted to the ICU of our tertiary hospital between 19-03-2020 and 17-05-2020. Point-of-care fully automated flow cytometry was performed prior to ICU admission, measuring the neutrophil activation/maturation markers CD10, CD11b, CD16 and CD62L. Neutrophil receptor expression was compared between patients who did or did not develop PE (as diagnosed on CT angiography) during or after their ICU stay. RESULTS: Among 25 eligible ICU patients, 22 subjects were included for analysis, of whom nine developed PE. The median (IQR) time between neutrophil phenotyping and PE occurrence was 9 (7-12) days. A significant increase in the immune-suppressive neutrophil phenotype CD16bright /CD62Ldim was observed on the day of ICU admission (P = 0.014) in patients developing PE compared to patients who did not. CONCLUSION: The increase in this neutrophil phenotype indicates that the increased number of CD16bright /CD62Ldim neutrophils might be used as prognostic marker to predict those patients that will develop PE in critical COVID-19 patients.