Objective: To investigate the effect of crude antigens of Ascaris lumbricoides on the secretion of IL-6 and TGF-β of human lung adenocarcinoma cells (A549 cells), and the apoptosis of A549 cells.
Methods: Crude antigens of A. lumbricoides were prepared. A549 cells were co-cultured with 25, 125, and 500 µg/ml crude antigens of A. lumbricoides for 1, 18, and 24 h, named as low concentration group, medium concentration group, and high concentration group, respectively. Meanwhile, A549 cells were co-cultured with culture medium (negative control) and 12.5 µg/ml adriamycin (positive control). The apoptosis rate was detected by using Annexin V-FITC apoptosis detection kit. The cell changes were determined by flow cytometry. The levels of mRNA expression of IL-6 and TGF-β were detected by ELISA and real time PCR, respectively.
Results: The apoptosis rate of A549 cells induced by crude antigens for 1, 18, and 24 h was significantly higher than that of negative control (P < 0.01). The apoptosis rate in medium concentration group (treated for 18 h) was highest [(47.10 ± 3.68)%]. After co-culture with 125 µg/ml crude antigens for 18 h, the proportion of G0/G1 phase cells increased and that of S phase cells decreased, and there was a significant difference between medium concentration group and negative control group. At the same time, the level of IL-6 increased with the increasing concentration of crude antigens. However, no significant difference was found in the level of TGF-β among the groups. In the medium concentration group, mRNA expression levels of IL-6 (5.95 ± 0.31) and TGF-β (3.43 ± 0.35) of A549 cells reached peak on the 18th hour, and were significantly higher than that of the control (P < 0.01).
Conclusion: The cell cycle of A549 cells is blocked in G0/G1 phase induced by crude antigens of A. lumbricoides. And the apoptosis may be related to the changes in the level of TGF-β and IL-6.