Knockdown of annexin A2 enhances the host cell apoptosis induced by Eimeria tenella

Annexin A2 (ANXA2) is a multifunctional protein involved in host-pathogen interactions during viral and parasitic infections. To investigate the role of ANXA2 in host cell apoptosis induced by <i>Eimeria tenella</i>, RNA interference (RNAi) was employed to specifically downregulate ANXA2 expression. Primary cultures of chicken embryonic cecal epithelial cells were established and subjected to <i>E. tenella</i> sporozoite infection. A comprehensive analytical approach integrating hematoxylin-eosin staining, Hoechst-Annexin V-PI triple-staining, and caspase-3 activity quantification was used. Western-blot and RT-qPCR were performed to assess transcriptional and translational changes in key apoptosis-related factors, including B-cell lymphoma (Bcl-2) and Bcl-2-associated X protein (Bax). Additionally, the dynamic expression of ANXA2 was analyzed to clarify its function in the parasite-host interaction. The results showed that the ANXA2 expression in the <i>E. tenella</i> group increased at 4 h after inoculation but decreased at 24 to 96 h compared to the control group (<i>P</i> < 0.01). Following ANXA2 knockdown, the cell apoptosis rate, caspase-3 activity, and Bax expression levels were significantly increased (<i>P</i> < 0.01), whereas the infection rate and Bcl-2 expression levels were significantly decreased (<i>P</i> < 0.01) compared to the group infected with <i>E. tenella</i> alone. In conclusion, ANXA2 serves as a critical regulator of host cell responses during <i>E. tenella</i> infection. RNAi-mediated suppression of ANXA2 expression significantly enhances apoptosis induced by <i>E. tenella</i>. This study establishes a foundation for further exploration of therapeutic targets to reduce host tissue damage, indicating that targeting ANXA2 may be a viable approach for controlling coccidiosis.