New insight into Intestinal Mast Cells revealed by Single-Cell RNAseq

Mast cells are tissue-resident immune cells distributed in all tissues and strategically located close to blood and lymphatic vessels and nerves. Thanks to the expression of a wide array of receptors, mast cells act as tissue sentinels, able to detect the presence of bacteria and parasites and to respond to different environmental stimuli. Mast cells originate from bone marrow progenitors that enter the circulation and mature in peripheral organs under the influence of microenvironment factors, thus differentiating in heterogeneous tissue-specific subsets. Even though mast cell activation has been traditionally linked to IgE-mediated allergic reactions, a role for these cells in other pathological conditions including tumor progression has recently emerged. However, several aspects of mast cell biology remain to be clarified. The advent of single-cell RNA sequencing platforms has provided the opportunity to understand mast cell origin and differentiation as well as the phenotype and functions within different tissues, including the gut. This review recapitulates how single cell transcriptomic studies provided insight into mast cell development as well as into the functional role of intestinal MC subsets in health and disease.