Dendritic-cell diversity in equine blood revealed by single-cell transcriptomics
Ambre Baillou, Marius Botos, Simone Oberhaensli, Iva Cvitas, Sigridur Jonsdottir, Anja Ziegler, Francisco Brito, Artur Summerfield, Eliane Marti, Stephanie C TalkerAbstract
Introduction
Detailed classification of equine dendritic cells (DC) is necessary to address various research questions such as the role of DC subsets in immune-mediated diseases of horses.
Methods
We applied single-cell RNA sequencing (scRNA-seq) on DC enriched from the blood of two horses. All main DC subsets were detected by key gene expression, including conventional DC type 1 (cDC1; XCR1) and type 2 (cDC2; FCER1A, CD1E) as well as plasmacytoid DC (pDC; TCF4). In addition, we detected a small cluster of hematopoietic progenitors, as well as transitional DC (tDC; FCER1A, TCF4) and putative DC type 3 (DC3; FLT3, CD163).
Results
Our data confirms the previously reported phenotype of equine pDC (Flt3+MHC-IIlowCADM1lowCD172aint), cDC1 (Flt3+MHC-IIhighCADM1highCD172alow-int) and cDC2 (Flt3+MHC-IIhighCADM1intCD172ahigh), while also highlighting considerable CD14 expression for cDC2. Two subclusters of equine cDC2 were found to be enriched in FCER1A or CX3CR1 transcripts (cDC2.1 and cDC2.2, respectively), with suggested enhanced extravasation and T-cell stimulatory capacities of the latter. Conservation of DC subsets across species (horse, pig, human, mouse) was illustrated by enrichment analyses with subset-specific gene signatures and by cross-species data integration with publicly available scRNA-seq datasets.
Conclusion
Our atlas of equine blood DC is a valuable resource for comparative analyses, and it forms the foundation for understanding the involvement of distinct DC subsets in infections and immune-mediated pathologies.