I am interested in this and there is growing research looking at differences in the surfactant system in patients with differing COVID-19 lung injury. This is important, because the type II respiratory epithelilal cell synthesizes and secretes surfactant and the surfactant proteins (SP). Sars-cov-2 attacks the lung via the ACE-2 receptor on these type 2 respiratory epithelial cells.
Surfactant are complex amphiphilic molecules. Meaning it has a hydrophilic glycoprotein head and a long fatty acid hyrophobic tail. Phosphatydilcholine (found in lecithin) is common surfactant. They organize together to form micelles which adsorb at interfaces between oil and water in the small alveolar sacs where gas exchange occurs. The micelles coat the alveolar sacs at the terminus of the bronchial tree. This has the effect of lowering surface tension of alveoli at low lung volumes and prevents micro-collapse of the alveoli. It is crucial in counter acting alveolar collapse especially in condition of lung injury such as ARDS. Alveolar collapse has the effect of exacerbating inflammation and further lung injury.
Surfactant production, instillation and clearance is governed by 4 proteins synthesized by the type 2 cells. They include the hydrophilic SP-A and SP-D, and the hydrophobic SP-B and SP-C. SP-A and SP-D are involved in innate local lung immunity, including viral clearance thru macropha*ge p*hago*cytosis (TexAgs wouldn't accept the terms? so had to put asterisks). SP-B and SP-C are more intimately involved in surfactant production and synthesis. Absence of and mutations in SP-B and SP-C are associated with neonatal ARDS, and as well as pulmonary fibrosis (SP-C).
SP-D interacts with sars-cov-2 S spike protein and is thought to be crucial in immunity and clearance of the virus from infected lungs. Research is ongoing looking at differences in SP activity, especially SP-D, in COVID-19. Also, surfactant deficiency is theorized to play a large role in heterogeneity in lung injury patterns in COVID-19.
Surfactant replacement therapy has been used effectively in ARDS in children for years. It has had variable results in adult ARDS. However, several trials of surfactant replacement are ongoing in COVID-19 related ARDS currently.
Probably TLDR I know but I wanted to share thoughts about this because I haven't seen it mentioned in these discussions.
Too many articles to link but there's many to read for those interested.
https://www.frontiersin.org/articles/10.3389/fimmu.2012.00131/full
Surfactant are complex amphiphilic molecules. Meaning it has a hydrophilic glycoprotein head and a long fatty acid hyrophobic tail. Phosphatydilcholine (found in lecithin) is common surfactant. They organize together to form micelles which adsorb at interfaces between oil and water in the small alveolar sacs where gas exchange occurs. The micelles coat the alveolar sacs at the terminus of the bronchial tree. This has the effect of lowering surface tension of alveoli at low lung volumes and prevents micro-collapse of the alveoli. It is crucial in counter acting alveolar collapse especially in condition of lung injury such as ARDS. Alveolar collapse has the effect of exacerbating inflammation and further lung injury.
Surfactant production, instillation and clearance is governed by 4 proteins synthesized by the type 2 cells. They include the hydrophilic SP-A and SP-D, and the hydrophobic SP-B and SP-C. SP-A and SP-D are involved in innate local lung immunity, including viral clearance thru macropha*ge p*hago*cytosis (TexAgs wouldn't accept the terms? so had to put asterisks). SP-B and SP-C are more intimately involved in surfactant production and synthesis. Absence of and mutations in SP-B and SP-C are associated with neonatal ARDS, and as well as pulmonary fibrosis (SP-C).
SP-D interacts with sars-cov-2 S spike protein and is thought to be crucial in immunity and clearance of the virus from infected lungs. Research is ongoing looking at differences in SP activity, especially SP-D, in COVID-19. Also, surfactant deficiency is theorized to play a large role in heterogeneity in lung injury patterns in COVID-19.
Surfactant replacement therapy has been used effectively in ARDS in children for years. It has had variable results in adult ARDS. However, several trials of surfactant replacement are ongoing in COVID-19 related ARDS currently.
Probably TLDR I know but I wanted to share thoughts about this because I haven't seen it mentioned in these discussions.
Too many articles to link but there's many to read for those interested.
https://www.frontiersin.org/articles/10.3389/fimmu.2012.00131/full
