Wei Fang1, Jingyu Huang1, Jun Wang1, Tengyi Huang1, Dajia Lin1, Jun Yin1. 1. Department of Clinical Laboratory Medicine, Second Affiliated Hospital of Shantou University Medical College Shantou, Guangdong Province, People's Republic of China.
Abstract
OBJECTIVE: To investigate the effect of silencing the interleukin (IL)-6 gene on the induction of inflammation, oxidative stress and apoptosis in Mycoplasma pneumoniae (MP) infected A549 cells and its mechanism of action. METHODS: IL-6 small interfering RNA (siRNA) was synthesized and transfected into A549 cells, which were divided into a blank control group, a negative control group, and an IL-6 siRNA group. The mRNA and protein expression of IL-6 and the protein expression of CyclinD1, Cleaved caspase-3, Bax, B-cell lymphoma 2 (Bcl-2), signal transducer and activator of transcription 3 (STAT3), phosphorylated STAT3 (p-STAT3), matrix metalloproteinase (MMP)-2 and MMP-9 were measured. Besides, cell viability and apoptosis were determined. Additionally, the levels of malondialdehyde (MDA), superoxide dismutase (SOD), glutathione peroxidase (GSH-PX), IL-1β, IL-8 and tumor necrosis factor (TNF)-α were measured. RESULTS: The mRNA and protein levels of IL-6 in the IL-6 siRNA group were lower than those in the blank and negative control groups (P < 0.05). The IL-6 siRNA group had higher viability but lower apoptosis rate of A549 cells at 24 h, 48 h and 72 h than the blank and negative control groups (P < 0.05). The IL-6 siRNA group had lower protein expression levels of Cleaved caspase-3 and Bax, but higher protein expression levels of CyclinD1 and Bcl-2 than the blank and negative control groups (P < 0.05). The IL-6 siRNA group had lower levels of IL-6, IL-8, TNF-α and MDA, but higher levels of SOD and GSH-PX than the blank and negative control groups (P < 0.05). CONCLUSION: Silencing the IL-6 gene can reduce the MP-induced inflammatory response and oxidative stress of A549 cells, enhance cell viability and inhibit apoptosis. Meanwhile, it was also found that STAT3 expression was inhibited after silencing IL-6 gene expression. Therefore, it is speculated that IL-6 may play a role by regulating STAT3, but its exact molecular biological mechanism still needs to be further explored. AJTR
OBJECTIVE: To investigate the effect of silencing the interleukin (IL)-6 gene on the induction of inflammation, oxidative stress and apoptosis in Mycoplasma pneumoniae (MP) infected A549 cells and its mechanism of action. METHODS: IL-6 small interfering RNA (siRNA) was synthesized and transfected into A549 cells, which were divided into a blank control group, a negative control group, and an IL-6 siRNA group. The mRNA and protein expression of IL-6 and the protein expression of CyclinD1, Cleaved caspase-3, Bax, B-cell lymphoma 2 (Bcl-2), signal transducer and activator of transcription 3 (STAT3), phosphorylated STAT3 (p-STAT3), matrix metalloproteinase (MMP)-2 and MMP-9 were measured. Besides, cell viability and apoptosis were determined. Additionally, the levels of malondialdehyde (MDA), superoxide dismutase (SOD), glutathione peroxidase (GSH-PX), IL-1β, IL-8 and tumor necrosis factor (TNF)-α were measured. RESULTS: The mRNA and protein levels of IL-6 in the IL-6 siRNA group were lower than those in the blank and negative control groups (P < 0.05). The IL-6 siRNA group had higher viability but lower apoptosis rate of A549 cells at 24 h, 48 h and 72 h than the blank and negative control groups (P < 0.05). The IL-6 siRNA group had lower protein expression levels of Cleaved caspase-3 and Bax, but higher protein expression levels of CyclinD1 and Bcl-2 than the blank and negative control groups (P < 0.05). The IL-6 siRNA group had lower levels of IL-6, IL-8, TNF-α and MDA, but higher levels of SOD and GSH-PX than the blank and negative control groups (P < 0.05). CONCLUSION: Silencing the IL-6 gene can reduce the MP-induced inflammatory response and oxidative stress of A549 cells, enhance cell viability and inhibit apoptosis. Meanwhile, it was also found that STAT3 expression was inhibited after silencing IL-6 gene expression. Therefore, it is speculated that IL-6 may play a role by regulating STAT3, but its exact molecular biological mechanism still needs to be further explored. AJTR