Paralichthys olivaceus Raw sequence reads

Interferon gamma, the member of type II interferons, is a major driver and effector cytokine for Th1 cells and plays broad roles in regulating the function of immune cells. Teleost fish represents the oldest living bony vertebrates containing T-lymphocyte subsets. However, whether or how the regulatory mechanisms of IFN-gamma on Th1 cells occur in teleost fish remain unknown. Therefore, in this study, full-length transcriptome sequencing was performed to analyze the differentially expressed genes (DEGs) and signaling pathways in the IFN-gamma stimulated lymphocytes of flounder (Paralichthys olivaceus). Meanwhile, the expression of Th1 cell-specific transcription factor T-bet and the proliferation of CD4+ T cells were further investigated, respectively. The results showed that, after IFN-gamma stimulation, 811 genes were upregulated and 1107 genes were downregulated in the lymphocytes. Th1 and Th2 cell differentiation pathway was enriched from DEGs, and eight genes, especially IFN-gamma, in the Th1 cell differentiation pathway were shown to be upregulated. In addition, CD4-1+ T and CD4-2+ T lymphocytes proliferated significantly after IFN-gamma stimulation, accompanied by increased T-bet expression in lymphocytes. Collectively, these results suggested that IFN-gammacan induce a Th1-type immune response in flounder, thus providing novel perspectives into the differentiation of CD4+ T lymphocytes in teleost.