Vaccine-induced modulation of gene expression in turbot peritoneal cells: A microarray approach

We used a microarray approach to examine changes in gene expression in turbot peritoneal cells after injection of the fish with vaccines containing the ciliate parasite Philasterides dicentrarchi as antigen and one of the following adjuvants: chitosan-PVMMA microspheres, Freund´s complete adjuvant, aluminium hydroxide gel, and Matrix-Q (Isconova, Sweden). We identified 374 genes that were differentially expressed in all groups of fish. Forty-two genes related to tight junctions and focal adhesions and/or actin cytoskeleton were differentially expressed in free peritoneal cells. The profound changes in gene expression related to cell adherence and cytoskeleton may be associated with cell migration and also with the formation of cell-vaccine masses and their attachment to the peritoneal wall. Thirty-five genes related to apoptosis were differentially expressed. Although most of the proteins coded for by these genes have a proapoptotic effect, others are antiapoptotic, indicating that both types of signal occur in peritoneal leukocytes of vaccinated fish. Interestingly, many of the genes related to lymphocytes and lymphocyte activity were downregulated in the groups injected with vaccine. We also observed decreased expression of genes related to antigen presentation, suggesting that macrophages (which were abundant in the peritoneal cavity after vaccination) did not express these genes during the early inflammatory response in the peritoneal cavity. Finally, several genes that participate in the inflammatory response were differentially expressed, and most participated in resolution of inflammation, indicating that an M2 macrophage response is generated in the peritoneal cavity of fish one day post vaccination. The early cell response in the peritoneal cavity after vaccination was measured at 1, 3 and 5 days after injection with antigen in PBS, with microespheres containing covalently linked antigen to their surface in PBS or with a mixture of antigen and the following adjuvants: Montanide Isa 763 A, aluminium hydroxide gel or Matrix-Q. The control group was injected intraperitoneally with phosphate-buffered saline.