Liver response of rabbits to Eimeria coecicola infections

Intestinal coccidiosis of rabbits induced by E. coecicola causes enormous economic losses in rabbit farms. Here, we investigate the effect of E. coecicola on the liver of the rabbit Oryctolagus cuniculus. On day 7 p.i., fecal expulsion of E. coecicola oocysts is maximal and rabbits have lost approximately 25% of their weight. The liver, though not targeted by parasites, exhibits several signs of moderate inflammations, i.e., inflammatory cellular infiltrations around the central vein, dilatated blood sinusoids, increase in vacuolated hepatocytes, hypertrophic Kupffer cells, and lipid peroxidation as well as decreases in catalase and superoxide dismutase activities. Liver injuries are also indicated by an increase in blood plasma, by an increase in liver enzymes such as alanine transaminase, aspartate transaminase, alkaline phosphatase, and gamma glutamyl transferase, and a decrease in total protein and albumin. Circulating neutrophils have increased from 61% on day 0 p.i. to 71.3% on day 7 p.i., while lymphocytes are decreased from 37% to 26%. Agilent two-color oligo microarray technology, in combination with quantitative PCR, reveals that the expressions of 56 genes are upregulated and that of 22 genes are downregulated in the liver. The genes are largely involved in metabolism, calcium homeostasis, transport, and diverse signaling processes in the liver. In addition, numerous genes encoding for different regions of T-cell receptor as well as IgM, IgG, and IgA antibodies are both up- and downregulated in the liver by E. coecicola infections. The latter data suggest that the liver is not only 'passively' inflamed by intestinal infections with E. coecicola but rather is actively involved in the host defense against the intestinal Eimeria parasites.