Transcriptome Profiling of Porcine Naïve, Intermediate and Terminally Differentiated CD8+ T Cells
Emil Lagumdzic, Clara P. S. Pernold, Marta Viano, Simone Olgiati, Michael Schmitt, Kerstin H. Mair, Armin Saalmüller
Abstract
The pig has the potential to become a leading research model for human diseases, pharmacological and transplantation studies. Since there are many similarities between humans and pigs, especially concerning anatomy, physiology and metabolism, there is necessity for a better understanding of the porcine immune system. In adaptive immunity, cytotoxic T lymphocytes (CTLs) are essential for host defense. However, most data on CTLs come from studies in mice, non-human primates and humans, while detailed information about porcine CD8 + CTLs is still sparse. Aim of this study was to analyze transcriptomes of three subsets of porcine CD8β + T-cell subsets by using next-generation sequencing technology. Specifically, we described transcriptional profiles of subsets defined by their CD11a/CD27 expression pattern, postulated as naïve (CD8β + CD27 + CD11a low ), intermediate differentiated (CD8β + CD27 dim CD11a + ), and terminally differentiated cells (CD8β + CD27 - CD11a high ). Cells were analyzed in ex vivo condition as well as upon in vitro stimulation with concanavalin A (ConA) and PMA/ionomycin. Our analyses show that the highest number of differentially expressed genes was identified between naïve and terminally differentiated CD8 + T-cell subsets, underlining their difference in gene expression signature and respective differentiation stages. Moreover, genes related to early ( IL7-R , CCR7 , SELL , TCF7, LEF1 , BACH2 , SATB1 , ZEB1 and BCL2 ) and late ( KLRG1 , TBX21 , PRDM1 , CX3CR1, ZEB2 , ZNF683 , BATF , EZH2 and ID2 ) stages of CD8 + T-cell differentiation were highly expressed in the naïve and terminally differentiated CD8 + T-cell subsets, respectively. Intermediate differentiated CD8 + T-cell subsets shared a more comparable gene expression profile associated with later stages of T-cell differentiation. Genes associated with cytolytic activity ( GNLY , PRF1 , GZMB , FASL , IFNG and TNF ) were highly expressed in terminally and intermediate differentiated CD8 + T-cell subsets, while naïve CD8 + T cells lacked expression even after in vitro stimulation. Overall, PMA/ionomycin stimulation induced much stronger upregulation of genes compared to stimulation with ConA. Taken together, we provided comprehensive results showing transcriptional profiles of three differentiation stages of porcine CD8 + T-cell subsets. In addition, our study provides a powerful toolbox for the identification of candidate markers to characterize porcine immune cell subsets in more detail.