Correlation of alpha-1 antitrypsin levels and exosome associated neutrophil elastase endothelial injury in subjects with SARS-CoV2 infection.

BACKGROUND: Severe acute respiratory syndrome caused by a novel coronavirus 2 (SARS-CoV-2) has infected more than 18 million people worldwide. The activation of endothelial cells is a hallmark of signs of SARS-CoV-2 infection that includes altered integrity of vessel barrier and endothelial inflammation. OBJECTIVES: Pulmonary endothelial activation is suggested to be related to the profound neutrophil elastase (NE) activity, which is necessary for sterilization of phagocytosed bacterial pathogens. However, unopposed activity of NE increases alveolocapillary permeability and extracellular matrix degradation. The uncontrolled protease activity of NE during the inflammatory phase of lung diseases might be due to the resistance of exosome associated NE to inhibition by alpha-1 antitrypsin. METHOD: 31 subjects with a diagnosis of SARS-CoV2 infection were recruited in the disease group and samples from 30 voluntaries matched for age and sex were also collected for control. RESULTS: We measured the plasma levels of exosome-associated NE in SARS-CoV-2 patients which, were positively correlated with sign of endothelial damage in those patients as determined by plasma levels of LDH. Notably, we also found strong correlation with plasma levels of alpha-1 antitrypsin and exosome-associated NE in SARS-CoV-2 patients. Using macrovascular endothelial cells, we also observed that purified NE activity is inhibited by purified alpha-1 antitrypsin while, NE associated with exosomes are resistant to inhibition and show less sensitivity to alpha-1 antitrypsin inhibitory activity, in vitro. CONCLUSIONS: Our results point out the role of exosome-associated NE in exacerbation of endothelial injury in SARS-CoV-2 infection. We have demonstrated that exosome-associated NE could be served as a new potential therapeutic target of severe systemic manifestations of SARS-CoV-2 infection.

A Review of Alpha-1 Antitrypsin Binding Partners for Immune Regulation and Potential Therapeutic Application.

Alpha-1 antitrypsin (AAT) is the canonical serine protease inhibitor of neutrophil-derived proteases and can modulate innate immune mechanisms through its anti-inflammatory activities mediated by a broad spectrum of protein, cytokine, and cell surface interactions. AAT contains a reactive methionine residue that is critical for its protease-specific binding capacity, whereby AAT entraps the protease on cleavage of its reactive centre loop, neutralises its activity by key changes in its tertiary structure, and permits removal of the AAT-protease complex from the circulation. Recently, however, the immunomodulatory role of AAT has come increasingly to the fore with several prominent studies focused on lipid or protein-protein interactions that are predominantly mediated through electrostatic, glycan, or hydrophobic potential binding sites. The aim of this review was to investigate the spectrum of AAT molecular interactions, with newer studies supporting a potential therapeutic paradigm for AAT augmentation therapy in disorders in which a chronic immune response is strongly linked.

d-Galactose treatment increases ACE2, TMPRSS2, and FURIN and reduces SERPINA1 mRNA expression in A549 human lung epithelial cells.

Several comorbidities including diabetes, immune deficiency, and chronic respiratory disorders increase the risk of severe Covid-19 and fatalities among SARS-CoV-2 infected individuals. Severe Covid-19 risk among diabetes patients may reflect reduced immune response to viral infections. SARS-CoV-2 initially infects respiratory tract epithelial cells by binding to the host cell membrane ACE2, followed by proteolytic priming for cell entry by the host cell membrane serine protease TMPRSS2. Additionally, the protease FURIN facilitates cell exit of mature SARS-CoV-2 virions. Alpha-1 antitrypsin (AAT), the major plasma serine protease inhibitor, encoded by SERPINA1, is known to promote immune response to viral infections. AAT inhibits neutrophil elastase, a key inflammatory serine protease implicated in alveolar cell damage during respiratory infections, and AAT deficiency is associated with susceptibility to lung infections. AAT is implicated in Covid-19 as it inhibits TMPRSS2, a protease essential for SARS-CoV-2 cell entry. Here we show that treatment of A549 human lung epithelial cells for 7 days with 25 mM d-galactose, an inducer of diabetic-like and oxidative stress cellular phenotypes, leads to increased mRNA levels of ACE2, TMPRSS2, and FURIN, along with reduced SERPINA1 mRNA. Together, the dysregulated transcription of these genes following d-galactose treatment suggests that chronic diabetic-like conditions may facilitate SARS-CoV-2 infection of lung epithelial cells. Our findings may in part explain the higher severe Covid-19 risk in diabetes, and highlight the need to develop special treatment protocols for diabetic patients.

Ethnic differences in alpha-1 antitrypsin deficiency allele frequencies may partially explain national differences in COVID-19 fatality rates.

Infection rates, severity, and fatalities due to COVID-19, the pandemic mediated by SARS-CoV-2, vary greatly between countries. With few exceptions, these are lower in East and Southeast Asian and Sub-Saharan African countries compared with other regions. Epidemiological differences may reflect differences in border closures, lockdowns, and social distancing measures taken by each county, and by cultural differences, such as common use of face masks in East and Southeast Asian countries. The plasma serine protease inhibitor alpha-1 antitrypsin was suggested to protect from COVID-19 by inhibiting TMPRSS2, a cell surface serine protease essential for the SARS-CoV-2 cell entry. Here, we present evidence that population differences in alpha-1 antitrypsin deficiency allele frequencies may partially explain national differences in the COVID-19 epidemiology. Our study compared reported national estimates for the major alpha-1 antitrypsin deficiency alleles PiZ and PiS (SERPINA1 rs28929474 and rs17580, respectively) with the Johns Hopkins University Coronavirus Resource Center dataset. We found a significant positive correlation (R = .54, P = 1.98e-6) between the combined frequencies of the alpha-1 antitrypsin PiZ and PiS deficiency alleles in 67 countries and their reported COVID-19 mortality rates. Our observations suggest that alpha-1 antitrypsin deficiency alleles may contribute to national differences in COVID-19 infection, severity, and mortality rates. Population-wide screening for carriers of alpha-1 antitrypsin deficiency alleles should be considered for prioritizing individuals for stricter social distancing measures and for receiving a SARS-CoV-2 vaccine once it becomes available.

Alpha-1-antitrypsin: A possible host protective factor against Covid-19.

Understanding Covid-19 pathophysiology is crucial for a better understanding of the disease and development of more effective treatments. Alpha-1-antitrypsin (A1AT) is a constitutive tissue protector with antiviral and anti-inflammatory properties. A1AT inhibits SARS-CoV-2 infection and two of the most important proteases in the pathophysiology of Covid-19: the transmembrane serine protease 2 (TMPRSS2) and the disintegrin and metalloproteinase 17 (ADAM17). It also inhibits the activity of inflammatory molecules, such as IL-8, TNF-α, and neutrophil elastase (NE). TMPRSS2 is essential for SARS-CoV-2-S protein priming and viral infection. ADAM17 mediates ACE2, IL-6R, and TNF-α shedding. ACE2 is the SARS-CoV-2 entry receptor and a key component for the balance of the renin-angiotensin system, inflammation, vascular permeability, and pulmonary homeostasis. In addition, clinical findings indicate that A1AT levels might be important in defining Covid-19 outcomes, potentially partially explaining associations with air pollution and with diabetes. In this review, we focused on the interplay between A1AT with TMPRSS2, ADAM17 and immune molecules, and the role of A1AT in the pathophysiology of Covid-19, opening new avenues for investigating effective treatments.

Characterization of the Inflammatory Response to Severe COVID-19 Illness.

Rationale: Coronavirus disease (COVID-19) is a global threat to health. Its inflammatory characteristics are incompletely understood.Objectives: To define the cytokine profile of COVID-19 and to identify evidence of immunometabolic alterations in those with severe illness.Methods: Levels of IL-1ß, IL-6, IL-8, IL-10, and sTNFR1 (soluble tumor necrosis factor receptor 1) were assessed in plasma from healthy volunteers, hospitalized but stable patients with COVID-19 (COVIDstable patients), patients with COVID-19 requiring ICU admission (COVIDICU patients), and patients with severe community-acquired pneumonia requiring ICU support (CAPICU patients). Immunometabolic markers were measured in circulating neutrophils from patients with severe COVID-19. The acute phase response of AAT (alpha-1 antitrypsin) to COVID-19 was also evaluated.Measurements and Main Results: IL-1ß, IL-6, IL-8, and sTNFR1 were all increased in patients with COVID-19. COVIDICU patients could be clearly differentiated from COVIDstable patients, and demonstrated higher levels of IL-1ß, IL-6, and sTNFR1 but lower IL-10 than CAPICU patients. COVID-19 neutrophils displayed altered immunometabolism, with increased cytosolic PKM2 (pyruvate kinase M2), phosphorylated PKM2, HIF-1α (hypoxia-inducible factor-1α), and lactate. The production and sialylation of AAT increased in COVID-19, but this antiinflammatory response was overwhelmed in severe illness, with the IL-6:AAT ratio markedly higher in patients requiring ICU admission (P < 0.0001). In critically unwell patients with COVID-19, increases in IL-6:AAT predicted prolonged ICU stay and mortality, whereas improvement in IL-6:AAT was associated with clinical resolution (P < 0.0001).Conclusions: The COVID-19 cytokinemia is distinct from that of other types of pneumonia, leading to organ failure and ICU need. Neutrophils undergo immunometabolic reprogramming in severe COVID-19 illness. Cytokine ratios may predict outcomes in this population.