Relationship between Eimeria tenella development and host cell apoptosis in chickens

Abstract

Coccidiosis causes considerable economic losses in the poultry industry. At present, the pathology of coccidiosis is preventable with anticoccidials and vaccination, although at considerable cost to the international poultry industry. The purpose of the present study was to elucidate the relationship between Eimeria tenella development and host cell apoptosis in chickens, which provides a theoretical basis for further study of the injury mechanism of E. tenella and the prevention and treatment of coccidiosis. Cecal epithelial cells from chick embryo were used as host cells in vitro. In addition, flow cytometry, terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate (dUTP) nick-end labeling, and histopathological assays were used to detect the dynamic changes in E. tenella infection rates, DNA injury rates, and apoptosis rates in groups treated with and without the caspase-9 inhibitor Z-LEHD-FMK. Following E. tenella infection, we demonstrated that untreated cells had less apoptosis at 4 h and, inversely, more apoptosis at 24 to 120 h compared with control cells. Furthermore, after the application of Z-LEHD-FMK, terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling assays, and translation of phosphatidyl serines to the host cell plasma membrane surface, the treated group chick embryo cecal epithelial cells exhibited decreased apoptosis and DNA injuries (P<0.01) at 24 to 120 h. However, light microscopy showed that E. tenella infection rates of treated cells were higher (P<0.01) than untreated cells during the whole experimental period. Together, these observations suggest that E. tenella can protect host cells from apoptosis at early stages of development but can promote apoptosis during the middle to late stages. In addition, the inhibition of host cell apoptosis can be beneficial to the intracellular growth and development of E. tenella.

A modified method for purification of Eimeria tenella sporozoites

“…An earlier version of this protocol has been successfully implemented in in vitro studies (Zhang et al unpublished data, Rentería-Solís et al unpublished data). Purification of E. tenella sporozoites can also successfully be performed by other protocols such as DE-52 anion exchange chromatography (Schmarz et al 1984), Percoll gradients (Dulski an Turner 1988, Thabet et al 2015 or with a 1400-mesh filter (Zhang et al 2015). The protocol described in this report uses a plastic disposable 5-μm filter that perfectly fits to a 50-mL falcon tube.…”

“…Research on chicken Eimeria spp. brings insights into coccidian metabolism, genetics, epidemiology and hostparasite interaction (Györke et al 2013, Blake et al 2015, Zhang et al 2015. These developments could translate into improved therapies or preventive measurements.…”

“…As ethically responsible study designs, in vitro models are pivotal to fulfil the goals of the 3R principle in animal research (Russell and Burch 1959). Eimeria sporozoites are commonly used in in vitro studies (Zhou et al 2013, Thabet et al 2015, Zhang et al 2015, Bussière et al 2018, Zhang et al 2018. Sporozoites are the first cell invasive stage during eimeriosis.…”

“…Purification of Eimeria sporozoites is an important step before cell culture infection. There are currently some purification methods available (Schmatz et al 1984, Dulski and Turner 1988, Zhang et al 2015. Purification of E. tenella sporozoites by DE-52 anion exchange chromatography is a method regularly used during in vitro studies (Schmatz et al 1984).…”

Effect of ATP and Bax on the apoptosis of Eimeria tenella host cells

“…The apoptosis rate of duodenal mucosal cells infected with Eimeria acervulina reaches the highest at 0.5 and 5 days [ 5 ]. E. tenella -infected embryo caecal epithelial cells have shown decreased apoptosis at early developmental stages (24 h or less) but have conversely shown increased apoptosis at the middle and late developmental stages (24–120 h) [ 6 ]. The degree to which the mitochondrial membrane KATP channel opens has been shown to decrease the apoptosis rate of cells infected with E. tenella and promote the development of E. tenella in chicken caecum epithelial cells [ 7 ].…”