Abstract Body (Do not enter title and authors here): Introduction: Acute lung injury results in endothelial dysfunction in systemic blood vessels, cardiac output, and an elevated risk of cardiovascular events. To date, no specific pharmacological interventions have been demonstrated to improve outcomes in acute lung injury. Long non-coding RNAs significantly influence the expression of various genes, impacting numerous physiological and pathological conditions. Previously, our team found that a lncRNA, named “long non-coding RNA, embryonic stem cells expressed 1” (Lncenc1), is strikingly upregulated in murine lungs following bacterial infection. CD59 is known to be highly expressed on vascular endothelial cells, where it blocks the complement system activation and membrane attack complex (MAC) deposition on the cell surface. However, the mechanism of Lncenc1 to CD59 on endothelial dysfunction and vascular permeability is currently unknown.
Hypothesis: Lncenc1 modulates MAC deposition through CD59 during bacteria-induced endothelial dysfunction.
Methods: Lncenc1 knockout (Lncenc1^-/-) mouse model was generated for this study. Hematoxylin-eosin (H&E) staining and lung wet-to-dry ratio measurement were confirmed to evaluate the severity of pulmonary edema. Pulmonary vascular permeability was induced by Klebsiella pneumoniae or Lipopolysaccharide and measured with Evans blue and fluorescein dye by tail-vein injection. Primary murine endothelial cells were isolated from mice for experimental use. Immunofluorescence staining and Western Blot were used to determine the MAC C5b-9 expression under infected conditions.
Results: Our result indicates that Lncenc1^-/- mice exhibit improved outcomes in terms of survival, pulmonary edema, and vascular leakage. Furthermore, microarray analysis revealed that CD59 is the most significantly upregulated in the lungs of Lncenc1^-/- mice compared to wild-type controls. We also found that Lncenc1 deficiency attenuates bacteria-induced MAC deposition in primary murine endothelial cells. Consistently, treatment with extracellular vesicle-carried CD59 was found to reduce bacteria-induced endothelial barrier leakage.
Conclusion: Our results demonstrate that Lncenc1 participates in the pathogenesis of bacteria-induced pulmonary edema and vascular leakage. Lncenc1 deficiency protects mice from bacteria-induced lung injury and endothelial barrier. Thus, Lncenc1 and its downstream modulator CD59 could be potential targets for the treatment of ALI-induced vascular dysfunction.