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A7538 - Knockdown of TFPI-Anchored Endothelial Cells Exacerbates LPS-Induced Acute Lung Injury Via NF-κB Signaling Pathway
Author Block: M. Shi; Department of Cardiothoracic Surgery, Huashan Hospital, Fudan University, Shanghai, China, ShangHai, China.
Background: As activation of the coagulation system is both a consequence and contributor to acute lung injury (ALI), pulmonary coagulopathy has become a potential target for therapeutic intervention in ALI patients. We investigated the effects and possible mechanisms of endothelial cell (EC)-anchored tissue factor pathway inhibitor (TFPI) on lipopolysaccharide (LPS)-induced ALI in mice. Methods: To assess the effect of endothelial cell-anchored TFPI deletion on ALI indices, TFPI knockout mice (cKO) mice were generated. Mice were instilled by direct intra-tracheal injection LPS for the preparation of an ALI model. Evans Blue Dye (EBD) was injected intravenously 2 h prior to animal sacrifice (48 h post-LPS). Lungs were fixed for histopathology and the prepared tissue was homogenized or used to extract bronchoalveolar lavage fluid (BALF) or detect EBD concentration. TFPIfl/fl and Tek mice with ALI were compared to wild-type (WT) mice with ALI to assess the effect of TFPI on endothelial barrier function and inflammation and assess its effects on the angiotensin-converting enzyme II (ACE2) protein and activation of the NF-kB pathways. Results: The deletion of endothelial TFPI markedly exacerbated LPS-induced histopathologic changes in lung, protein, and EBD extravasation into BALF, and promoted the secretion of the pro-inflammatory cytokines TNFα, IL-1β, and IL6. The number and infiltration of white blood cells (WBCs) from BALF and lung tissue of TFPI cKO mice with LPS-challenged ALI was increased compared to WT mice with LPS-challenged ALI. We also found further increased NF-κB activation and additional expression of VCAM-1 and reduction of ACE2 expression in TFPI cKO+LPS mice compared with WT+LPS mice. These results support that LPS-induced lung injury can enhance inflammatory and vascular permeability responses in TFPI cKO mice. Therefore, LPS via endotracheal instillation can induce more serious ALI in TFPI cKO mice. Conclusion: Endothelial-specific TFPI deficiency promoted LPS-induced pulmonary inflammation and endothelial barrier permeability, and also caused NF-κB signaling pathway activation in an LPS-induced ALI mouse model.