Abstract:

Objective To investigate the effect of miR⁃143⁃3p on lipopolysaccharide（LPS）⁃induced alveolar epithelial cell injury by regulating the Chemokine（C⁃x3⁃C unit）ligand 1/Chemokine（C⁃x3⁃C unit）receptor 1（CX3CL1/CX3CR1）signaling pathway. Methods Peripheral blood serum were collected from patients with acute lung injury/acute respiratory distress syndrome （ALI/ARDS）and healthy individuals. The samples were classified into ALI/ARDS group and normal group. Dual luciferase experiment was performed to confirm the targeting relationship between miR⁃143⁃3p and CX3CL1. Human alveolar epithelial cells A549 were cultured in vitro，and the cells were separated into normal control group，LPS group，LPS+NC mimic group（transfected with NC mimic）， LPS+miR⁃143⁃3p mimic group（transfected with miR⁃143⁃3p mimic），LPS+miR⁃143⁃3p mimic+pcDNA group （co⁃transfected with miR⁃143⁃3p mimic and pcDNA），and LPS+miR⁃143⁃3p mimic+pc⁃CX3CL1 group（co⁃trans⁃ fected with miR⁃143⁃3p mimic and pc⁃CX3CL1）. QRT⁃PCR was performed to measure the expression levels of miR⁃143⁃3p，CX3CL1 and CX3CR1 mRNAs. Western blot was performed to measure CX3CL1 and CX3CR1 proteinexpression. The viability and apoptosis of alveolar epithelial cells were detected by MTT and flow cytometry. ELISA was performed to analyze the levels of tumor necrosis factor⁃α（TNF⁃α），interleukin⁃1β（IL⁃1β），interleukin⁃6 （IL⁃6），vascular endothelial growth factor（VEGF）and procalcitonin（PCT）. Results Compared with the Normal group，the expression of miR ⁃143⁃3p（0.52 ± 0.05）in the peripheral blood of the ALI/ARDS group decreased， and the mRNA（1.79 ± 0.08），（1.65 ± 0.06）and protein（1.03 ± 0.15），（0.98 ± 0.12）expression of CX3CL1 and CX3CR1 increased（P < 0.05）. Compared with the Control group，the expression of miR⁃143⁃3p in the A549 cells of the LPS group decreased，the cell viability decreased，and the apoptosis rate［（23.56 ± 0.85）%］and the contents of TNF⁃α，IL⁃1β，IL⁃6，VEGF，and PCT increased（P < 0.05）. After miR⁃143⁃3p was overexpressed， cell viability was obviously increased，and the apoptosis rate［（13.74 ± 0.69）%］and the contents of TNF⁃α，IL⁃ 1β，IL⁃6，VEGF，and PCT were obviously reduced（P < 0.05）. The results of dual luciferase assay showed that miR⁃143⁃3p directly negatively regulated the expression of CX3CL1. CX3CL1 overexpression significantly reversed the effect of miR⁃143⁃3p overexpression on LPS⁃induced A549 cell damage and the inhibitory effect on CX3CR1 mRNA and protein expression（P < 0.05）. Conclusion MiR⁃143⁃3p can reduce the injury of alveolar epithelial cells induced by LPS by inhibiting the CX3CL1/CX3CR1 signaling pathway.

Key words:

MiR?143?3p, chemokine（C?x3?C unit）ligand 1, hemokine（C?x3?C unit）receptor 1, lipopolysaccharide, alveolar epithelial cells