A novel lineage transcription factor based analysis reveals differences in T helper cell subpopulation development in infected and intrauterine growth restricted (IUGR) piglets

Research in mouse and human clearly identified subsets of T helper (Th) cells based on nuclear expression of specific lineage transcription factors. In swine, however, transcription factor based detection of functional subpopulations of porcine Th cells by flow cytometry is so far limited to regulatory T cells via Foxp3.T-bet and GATA-3 are the transcription factors that regulate commitment to Th1 or Th2 cells, respectively. In this study we prove GATA-3 and T-bet expression in porcine CD4⁺ cells polarized in vitro. Importantly, GATA-3 and T-bet expressing cells were detectable in pigs infected with pathogens associated with Th2 and Th1 immune responses. Increased frequencies of GATA-3 positive CD4⁺ cells are found in vivo in pigs experimentally infected with the nematode Trichuris suis, whereas porcine reproductive and respiratory syndrome virus (PRRSV) infection elicited T-bet positive CD4⁺ T cells. Analysing the immune status of pre-weaning piglets with intrauterine growth restriction (IUGR) we found an increased expression of Foxp3, T-bet and GATA-3 in CD4⁺ and CD4⁺CD8⁺ double-positive T cells in systemic and intestinal compartments of IUGR piglets. Hence, we established the detection of porcine Th1 and Th2 cells via T-bet and GATA-3 and show that the porcine lineage transcription factors are differentially regulated very early in life depending on the developmental status.