Eimeria acervulina Microneme Protein 3 Inhibits Apoptosis of the Chicken Duodenal Epithelial Cell by Targeting the Casitas B-Lineage Lymphoma Protein

Abstract

Eimeria acervulina (E. acervulina) causes coccidiosis in poultry which persists as economic pain worldwide. Most damage to the intestinal mucosa results from apoptosis of the infected intestinal epithelial cells. The Microneme protein 3 (MIC3) protein is a key virulence factor in some parasites involved in host cell apoptosis inhibition. Here, we studied whether and how MIC3 affects the apoptosis in E. acervulina infected chicken duodenal epithelial cells. Through flow cytometry (FCM), we found that the presence of merozoites and the overexpression of MIC3 significantly decreased apoptosis and the activity of caspase-3 in chicken duodenal epithelial cells at 4, 6, and 8 h post merozoite infection (P < 0.01). Silencing the Casitas B-lineage lymphoma (CBL) protein, a host receptor for MIC3 with shRNA was shown to promote apoptosis in the chicken duodenal epithelial cells. The early apoptotic rate of host cells in the lentiviral-MIC3 group was significantly lower than that in the lentiviral-MIC3 + shRNA CBL group at 4 h after MIC3 expression (P < 0.01), and it was moderately decreased in the lentiviral-MIC3 + shRNA CBL group compared with that in the shRNA CBL group. Our data indicated that MIC3 inhibited early apoptosis of E. acervulina infected chicken duodenal epithelial cells by targeting host receptor-CBL protein. These findings unveiled one of the mechanisms of how intracellular parasites affect the apoptosis of infected host cells, which provided a deeper understanding of their pathogenesis.

What Do We Know about Surface Proteins of Chicken Parasites Eimeria?

“…E. maxima and E. acervulina are species causing malabsorption, also widely studied since they are found with high frequency in the field. In this sense, several immunogenic antigens have been studied in these two species: lactate dehydrogenase [ 121 ], MIF [ 87 ], cSZ-JN1 [ 122 ], cSZ2 [ 122 ], EaMIC3 [ 74 ], EaMIC5 [ 75 ] in addition to EaMIC2, 3-1E, and SAG1 [ 77 ] ( Table 1 ). In the case of E. mitis , only one immunogenic protein, EmiMIC3, has been characterised so far [ 86 ].…”

“…Few mic genes of E. acervulina (EaMIC2, EaMIC3, identified and their function has been investigated. EaM vival since it inhibited cell apoptosis [74]. They all we sporozoites, but EaMIC2 and EaMIC5 are located diffu was suggested that MICs might be translocated to the in contact with the host cell [75].…”

“…Few mic genes of E. acervulina (EaMIC2, EaMIC3, and EaMIC5) [ 56 , 74 , 75 , 76 ] have been identified and their function has been investigated. EaMIC3 has a key role in parasite survival since it inhibited cell apoptosis [ 74 ].…”

“…Few mic genes of E. acervulina (EaMIC2, EaMIC3, and EaMIC5) [ 56 , 74 , 75 , 76 ] have been identified and their function has been investigated. EaMIC3 has a key role in parasite survival since it inhibited cell apoptosis [ 74 ]. They all were found in the apical complex in sporozoites, but EaMIC2 and EaMIC5 are located diffused at both poles of merozoites.…”

Anatomical, histochemical, and immunohistochemical observations on the gastrointestinal tract of Gallinula chloropus (Aves: Rallidae)

“…Altered apoptosis and proliferation rates are frequently seen in disease conditions affecting the avian digestive tract [ 25 , 26 ]. Thus, mapping the normal distribution of apoptotic and/or proliferative cells within the avian digestive tract is a prerequisite for the proper diagnosis and treatment of such diseases [ 27 ].…”