Chick early amniotic fluid attenuates lipopolysaccharide-induced acute lung injury

Acute lung injury (ALI) and acute respiratory distress syndrome are major causes of acute respiratory failure and even death. Acute pneumonia can be accompanied by damage to the alveolar epithelium. <i>In vitro</i> functional experiments were performed by constructing inflammatory models in human alveolar epithelial cells. It was found that the chick early amniotic fluid (ceAF) extracted from SPF-grade early chicken embryos could significantly reduce the inflammation of human lung epithelial cells (Calu-3) induced by lipopolysaccharide (LPS) and COVID-19 protein pseudovirus, and reduce the gene expression of inflammatory factors. Pneumonia is one of the most common risk factors for causing ALI. An acute pneumonia model was constructed by LPS inhalation. Tail vein injection of ceAF significantly improved inspiratory and expiratory resistance, enhanced lung compliance, and reduced death rate due to acute pneumonia in mice. Neutrophil recruitment is an important feature of both acute inflammation and ALI. HE staining and immunohistochemical staining showed that ceAF treatment significantly reduced lung inflammatory edema and neutrophil cell aggregation, and promoted the resolution of inflammation in ALI, while reducing the inflammatory response in the blood. Further mass spectrometry experiments revealed that nicotinamide adenine dinucleotide (NAD⁺), guanosine and deoxyinosine were the primary components of ceAF. While each compound partially alleviated LPS-induced acute pneumonia, their effects were slightly weaker than those of ceAF, suggesting that ceAF's anti-inflammatory properties may arise from the synergistic action of these molecules.