Phenotypic and functional characterization of intestinal γδ T cell subsets in chicken

International audience

English. Gamma delta T cells (γδ T cells) are immune cells present in higher proportion in chickens compared to most other animal species. In the intestine, these cells are highly responsive to stimuli and possess functional plasticity under different inflammatory conditions. These cells are not well characterized in the gut mucosa of chickens. The objective of our study was therefore to identify subsets of γδ T cells along the intestinal tract. Intestinal cells were purified and based on the expression of CD4, CD8α and CD8β surface markers, we have defined 4 subsets of γδ T cells: Double Negative (DN), CD4+, CD8αα+, CD8αβ+. The diversity of γδ T cell subsets increases with age along the intestine, except in the caeca where high diversity is already present in early life. To characterize these subsets, caecal γδ T cells from 3-week-old chickens were sorted and gene expression analysis was performed using Fluidigm BioMarkTM Multiplex Quantitative PCR System. Interestingly, the analysis shows that CD4+ γδ T cells express genes associated with an immunoregulatory profile while the CD8+ γδ T cell present expression of genes related to a cytotoxic profile. Moreover, among CD8+ γδ T cells, the transcriptomic analysis of CD8αα+ subset clearly reveals a Th17-like polarization. However, the transcriptomic profile of CD8αβ+ γδ T cell is still unclear and appears to be a heterogeneous population. DN γδ T cell subset seems to be undifferentiated and also appears to be heterogeneous. The use of others markers would be usefull to separate successfully these populations based on their large expression profile. Overall, our data highlight two new subsets of chicken caecal γδ T cells with distinct functional activities. These results contribute to a better understanding of gut γδ T cells in the immune responses required to develop host-targeted therapies.