Doxycycline Induces Mitophagy and Suppresses Production of Interferon-ß in IPEC-J2 Cells

Xing, Yang; Liqi, Zhu; Jian, Lin; Qinghua, Yu; Qian, Yang

To investigate the sensitivity of IPEC-J2 cells to DOX, we determined the cytotoxic effect by testing cell viability. No inhibitory effect of DOX at therapeutic levels used in animal feed were detected in IPEC-J2 cells after a 24-h incubation (Figures 1A,B) . As DOX could induce apoptosis in different type cells (Fife et al., 1997; Wu et al., 2006; Lai et al., 2007; Mouratidis et al., 2007; Yeh et al., 2007) , we evaluated whether the growth inhibitory effect of DOX was associated with apoptosis or necrosis, we used a doublestaining method with fluorescein isothiocyanate-conjugated AnnexinV and propidium iodide to examine apoptosis in IPEC-J2 cells. The flow cytometric analysis did not reveal any distinct apoptotic changes in DOX-treated IPEC-J2 cells after 24 h of treatment ( Figures 1C,D) , or in 50 µg/ml DOXtreated IPEC-J2 cells for 24, 48, and 72 h ( Figure 1E ). Taken together, these results verify that DOX as food additives have little effect on IPEC-J2 cells viability, and would not induce apoptosis.