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1.
Mediators Inflamm ; 2021: 8874339, 2021.
Article in English | MEDLINE | ID: covidwho-1045644

ABSTRACT

Causes of mortality from COVID-19 include respiratory failure, heart failure, and sepsis/multiorgan failure. TLR4 is an innate immune receptor on the cell surface that recognizes pathogen-associated molecular patterns (PAMPs) including viral proteins and triggers the production of type I interferons and proinflammatory cytokines to combat infection. It is expressed on both immune cells and tissue-resident cells. ACE2, the reported entry receptor for SARS-CoV-2, is only present on ~1-2% of the cells in the lungs or has a low pulmonary expression, and recently, the spike protein has been proposed to have the strongest protein-protein interaction with TLR4. Here, we review and connect evidence for SARS-CoV-1 and SARS-CoV-2 having direct and indirect binding to TLR4, together with other viral precedents, which when combined shed light on the COVID-19 pathophysiological puzzle. We propose a model in which the SARS-CoV-2 spike glycoprotein binds TLR4 and activates TLR4 signalling to increase cell surface expression of ACE2 facilitating entry. SARS-CoV-2 also destroys the type II alveolar cells that secrete pulmonary surfactants, which normally decrease the air/tissue surface tension and block TLR4 in the lungs thus promoting ARDS and inflammation. Furthermore, SARS-CoV-2-induced myocarditis and multiple-organ injury may be due to TLR4 activation, aberrant TLR4 signalling, and hyperinflammation in COVID-19 patients. Therefore, TLR4 contributes significantly to the pathogenesis of SARS-CoV-2, and its overactivation causes a prolonged or excessive innate immune response. TLR4 appears to be a promising therapeutic target in COVID-19, and since TLR4 antagonists have been previously trialled in sepsis and in other antiviral contexts, we propose the clinical trial testing of TLR4 antagonists in the treatment of severe COVID-19. Also, ongoing clinical trials of pulmonary surfactants in COVID-19 hold promise since they also block TLR4.


Subject(s)
Angiotensin-Converting Enzyme 2/metabolism , COVID-19/immunology , Gene Expression Regulation , SARS-CoV-2 , Toll-Like Receptor 4/metabolism , Antiviral Agents/therapeutic use , Cell Proliferation , Humans , Immunity, Innate , Inflammation , Interferon Type I/metabolism , Lung/metabolism , Myocardium/metabolism , Protein Binding , Signal Transduction , Spike Glycoprotein, Coronavirus/metabolism , Surface-Active Agents
2.
J Biol Regul Homeost Agents ; 35(1): 1-4, 2021.
Article in English | MEDLINE | ID: covidwho-1034287

ABSTRACT

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is a highly contagious virus that infects humans and a number of animal species causing coronavirus disease-19 (COVID-19), a respiratory distress syndrome which has provoked a global pandemic and a serious health crisis in most countries across our planet. COVID-19 inflammation is mediated by IL-1, a disease that can cause symptoms such as fever, cough, lung inflammation, thrombosis, stroke, renal failure and headache, to name a few. Strategies that inhibit IL-1 are certainly helpful in COVID-19 and can represent one of the therapeutic options. However, until now, COVID-19 therapy has been scarce and, in many cases, ineffective, since there are no specific drugs other than the vaccine that can solve this serious health problem. Messenger RNA (mRNA) vaccines which are the newest approach, are already available and will certainly meet the many expectations that the population is waiting for. mRNA vaccines, coated with protected soft fatty lipids, use genetic mRNA (plus various inactive excipients) to make a piece of the coronavirus spike protein, which will instruct the immune system to produce specific antibodies. The soft fatty lipids allow the entry of mRNA into cells where it is absorbed into the cytoplasm and initiates the synthesis of the spike protein. In addition, vaccination also activates T cells that help the immune system respond to further exposure to the coronavirus. mRNA induces the synthesis of antigens of SARS-CoV-2 virus which stimulate the antibody response of the vaccinated person with the production of neutralizing antibodies. The new variant of the coronavirus-19 has been detected in the UK where, at the moment, the London government has imposed a lockdown with restrictions on international movements. The virus variant had already infected 1/4 of the total cases and in December 2020, it reached 2/3 of those infected in the UK. It has been noted that the spreading rate of the British variant could be greater than 70% of cases compared to the normal SARS-CoV-2 virus, with an R index growth of 0.4. Recent studies suggest that coronavirus-19 variation occurs at the level N501Y of the spike protein and involves 23 separate mutations on the spike, 17 of which are linked to the virus proteins, thus giving specific characteristics to the virus. In general, coronaviruses undergo many mutations that are often not decisive for their biological behavior and does not significantly alter the structure and the components of the virus. This phenomenon also occurs in SARS-CoV-2. It is highly probable that the variants recently described in the UK will not hinder vaccine-induced immunity. In fact, the variant will not break the vaccine although it may have some chance of making it a little less effective. Therefore, it is pertinent to think that the vaccine will work against the SARS-CoV-2 variant as well. In today's pandemic, the D614G mutation of the amino acid of corronavirus-19, which emerged in Europe in February 2020 is the most frequent form and causes high viral growth. The previously infrequent D614G mutation is now globally dominant. This variant, which is being tested by many international laboratories, is rapidly spreading across the countries and a series of vaccinated subjects are testing to see if their antibodies can neutralize the new variant of SARS-CoV-2. This variant has a very high viral growth and is less detectable with the RT-PCR technique in the laboratory. It has been reported that the British variant that increases viral load does not cause more severe effects in the respiratory tract and lung disease, therefore, it is certain that the variant is growing rapidly and must be kept under control; for this reason, laboratory data is expected impatiently. The study on the many variants that coronavirus-19 presents is very interesting and complete and clearer data on this topic will be ready in the near future. In addition, it is still unclear whether the different variants discovered in many countries, including Africa, share the same spike protein mutation and therefore, this is another study to elaborate on. In order to be certain and to not have unexpected surprises, we need to reduce the spread and the transmission speed of viral variants that could appear around the world, creating new pandemics. For this reason, the scientific community is on the alert since laboratory tests on serum antibodies from COVID-19 survivors have been reported to be less effective in attacking the variant. In light of the above, the scientific community must be on the alert as larger variants of the spike protein could escape vaccine-induced antibodies, which for now are of great help to the community and can save millions of lives. Deepening the study of spike protein mutations will help to better understand how to combat coronavirus-19 and its variants.


Subject(s)
COVID-19 , Animals , COVID-19/genetics , COVID-19/prevention & control , COVID-19 Vaccines , Communicable Disease Control , Europe , Humans , SARS-CoV-2
3.
Viruses ; 13(1)2020 12 29.
Article in English | MEDLINE | ID: covidwho-1004759

ABSTRACT

Due to the COVID-19 pandemic and multiple devastating forest fires, the 2020 meeting of the Rocky Mountain Virology Association was held virtually. The three-day gathering featured talks describing recent advances in virology and prion research. The keynote presentation described the measles virus paradox of immune suppression and life-long immunity. Special invited speakers presented information concerning visualizing antiviral effector cell biology in mucosal tissues, uncovering the T-cell tropism of Epstein-Barr virus type 2, a history and current survey of coronavirus spike proteins, a summary of Zika virus vaccination and immunity, the innate immune response to flavivirus infections, a discussion concerning prion disease as it relates to multiple system atrophy, and clues for discussing virology with the non-virologist. On behalf of the Rocky Mountain Virology Association, this report summarizes selected presentations.


Subject(s)
Societies, Scientific , Virology , Animals , Anniversaries and Special Events , Antiviral Agents , COVID-19 , Flavivirus Infections/immunology , Herpesvirus 4, Human , Humans , Immunity , Pandemics , Prions , SARS-CoV-2 , Spike Glycoprotein, Coronavirus , Vaccination , Zika Virus
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