Regulatory role of CCN1 in lipopolysaccharide-induced mouse acute lung injury

AIM: To observe the cellular location and expression change of cysteine-rich protein 61 (CYR61/CCN1) in lung tissues of the mice with lipopolysaccharide (LPS) intratracheal instillation, and to clarify the regulatory role of CCN1 expression in mediating inflammatory response. METHODS: The expression change of CCN1 in the lung tissues in vivo was observed by the method of immunohistochemistry, and immunofluorescence was employed to certify the cellular location of CCN1 in bronchial epithelial cells. Bronchial epithelial 16HBE cells were cultured in vitro, and the expression of CCN1 under the condition of LPS stimulation was quantified by RT-qPCR and Western blot with or without specific inhi-bitors of ERK1/2, JNK, P38 and PI3K signaling pathways. The mRNA expression levels of interleukin-6 (IL-6), IL-8, transformrg growth factor-β (TGF-β) and vascular endothlial growth factor (VEGF) were measured by RT-qPCR under the condition of recombinant CCN1 exposure or transfection with CCN1-siRNA. RESULTS: The results of immunohistochemistry indicated that CCN1 was primarily located in bronchial epithelium. The results of immunofluorescence revealed that CCN1 was localized in the cytoplasm. The specific inhibitors of ERK1/2, JNK, P38 and PI3K signaling pathways reversed the up-regulation of CCN1 upon LPS stimulation. Exposure to recombinant CCN1 resulted in the up-regulation of IL-6, IL-8, TGF-β and VEGF, while LPS-related up-regulation of IL-6, IL-8, TGF-β and VEGF was blocked by silencing of CCN1. CONCLUSION: Airway epithelium-derived CCN1 is up-regulated under the condition of lung injury and the regulatory mechanism involves ERK1/2, JNK, P38 and PI3K signal transduction pathways. CCN1 acts as an inflammatory mediator in amplification of inflammatory response, laying theoretical basis for the potential molecular therapeutic target of acute lung injury.