Is there a role of TNFR1 in acute lung injury cases associated with extracorporeal circulation?

Broussonin E against acute respiratory distress syndrome: the potential roles of anti-inflammatory

We applied network pharmacology and molecular docking analyses to study the efficacy of Broussonin E (BRE) in acute respiratory distress syndrome (ARDS) treatment and to determine the core components, potential targets, and mechanism of action of BRE. The SwissTargetprediction and SEA databases were used to predict BRE targets, and the GeneCards and OMIM databases were used to predict ARDS-related genes. The drug targets and disease targets were mapped to obtain an intersecting drug target gene network, which was then uploaded into the String database for protein-protein interaction network analysis. The intersecting gene was also uploaded into the DAVID database for gene ontology enrichment analysis and Kyoto encyclopedia of genes and genomes pathway analysis. Molecular docking analysis was performed to verify the interaction of BRE with the key targets. Finally, to validate the experiment in vivo, we established an oleic acid-induced ARDS rat model and evaluated the protective effect of BRE on ARDS by histological evaluation and enzyme-linked immunosorbent assay. Overall, 79 targets of BRE and 3974 targets of ARDS were predicted, and 79 targets were obtained after intersection. Key genes such as HSP90AA1, JUN, ESR1, MTOR, and PIK3CA play important roles in the nucleus and cytoplasm by regulating the tumor necrosis factor, nuclear factor-κB, and PI3K-Akt signaling pathways. Molecular docking results showed that small molecules of BRE could freely bind to the active site of the target proteins. In vivo experiments showed that BRE could reduce ARDS-related histopathological changes, release of inflammatory factors, and infiltration of macrophages and oxidative stress reaction. BRE exerts its therapeutic effect on ARDS through target and multiple pathways. This study also predicted the potential mechanism of BRE on ARDS, which provides the theoretical basis for in-depth and comprehensive studies of BRE treatment on ARDS.

Dichotomous Role of Tumor Necrosis Factor in Pulmonary Barrier Function and Alveolar Fluid Clearance

Alveolar-capillary leak is a hallmark of the acute respiratory distress syndrome (ARDS), a potentially lethal complication of severe sepsis, trauma and pneumonia, including COVID-19. Apart from barrier dysfunction, ARDS is characterized by hyper-inflammation and impaired alveolar fluid clearance (AFC), which foster the development of pulmonary permeability edema and hamper gas exchange. Tumor Necrosis Factor (TNF) is an evolutionarily conserved pleiotropic cytokine, involved in host immune defense against pathogens and cancer. TNF exists in both membrane-bound and soluble form and its mainly -but not exclusively- pro-inflammatory and cytolytic actions are mediated by partially overlapping TNFR1 and TNFR2 binding sites situated at the interface between neighboring subunits in the homo-trimer. Whereas TNFR1 signaling can mediate hyper-inflammation and impaired barrier function and AFC in the lungs, ligand stimulation of TNFR2 can protect from ventilation-induced lung injury. Spatially distinct from the TNFR binding sites, TNF harbors within its structure a lectin-like domain that rather protects lung function in ARDS. The lectin-like domain of TNF -mimicked by the 17 residue TIP peptide- represents a physiological mediator of alveolar-capillary barrier protection. and increases AFC in both hydrostatic and permeability pulmonary edema animal models. The TIP peptide directly activates the epithelial sodium channel (ENaC) -a key mediator of fluid and blood pressure control- upon binding to its α subunit, which is also a part of the non-selective cation channel (NSC). Activity of the lectin-like domain of TNF is preserved in complexes between TNF and its soluble TNFRs and can be physiologically relevant in pneumonia. Antibody- and soluble TNFR-based therapeutic strategies show considerable success in diseases such as rheumatoid arthritis, psoriasis and inflammatory bowel disease, but their chronic use can increase susceptibility to infection. Since the lectin-like domain of TNF does not interfere with TNF's anti-bacterial actions, while exerting protective actions in the alveolar-capillary compartments, it is currently evaluated in clinical trials in ARDS and COVID-19. A more comprehensive knowledge of the precise role of the TNFR binding sites versus the lectin-like domain of TNF in lung injury, tissue hypoxia, repair and remodeling may foster the development of novel therapeutics for ARDS.