Main Article Content
CTRP6, Extracellular Signal-regulated Kinase, Inflammation, Lipopolysaccharide, Lung Injury, Neutrophil Extracellular Traps, Sepsis
Background: Septic lung injury is associated with excessive neutrophil activation, while neutrophil extracellular traps formation contributes to inflammatory lung injury in sepsis. C1q/tumor necrosis factor–related protein-6 (CTRP6) is a paralog of adiponectin and exerts anti-inflammatory and antioxidant properties. The role of CTRP6 in sepsis-associated inflammatory lung injury was investigated in this study.
Methods: Mice were injected with lipopolysaccharides (LPS) intraperitoneally to establish the mouse sepsis model. They were first tail-vein injected with adenovirus-mediated overexpression CTRP6 (Ad-CTRP6) and then subjected to the LPS injection. Pathological changes in lungs were detected by hematoxylin and eosin staining. Inflammation cytokine levels in bronchoalveolar lavage fluid were assessed by qRT-PCR and ELISA. Flow cytometry was used to detect the number of neutrophils in bronchoalveolar lavage fluid, and immunofluorescence was performed to assess neutrophil extracellular traps.
Results: Lipopolysaccharides induced pulmonary congestion, interstitial edema, and alveolar wall thickening in the lungs, as well as upregulated lung histology score and wet/dry weight ratio. CTRP6 was reduced in lung tissues of septic mice. Injection with Ad-CTRP6 ameliorated extensive histopathological changes in LPS-induced mice and decreased lung histology score and wet/dry weight ratio. Overexpression of CTRP6 reduced the levels of TNF-α, IL-6, and IL-1β in septic mice. Injection with Ad-CTRP6 also decreased the number of neutrophils and downregulated Cit-H3 and myeloperoxidase polymers in septic mice. Protein expression of p-ERK in septic mice was reduced by overexpression of CTRP6.
Conclusion: CTRP6 attenuated septic lung injury, exerted anti-inflammatory effect, and suppressed neutrophil extracellular traps formation against sepsis through inactivation of extracellular signal-regulated kinase signaling.
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