Mast cell tissue heterogeneity and specificity of immune cell recruitment

Abstract

Mast cells occupy a unique niche within tissues as long lived perpetrators of IgE mediated hypersensitivity and anaphylaxis, as well as other immune responses. However, mast cells are not identical in different tissues and the impact of this tissue heterogeneity on the interaction with other immune cells and on defined immune responses is still unclear. In this review, we synthesize the characteristics of mast cell heterogeneity in the gut and the skin. Furthermore, we attempt to connect mast cell heterogeneity with functional diversity by exploring differences in mast cell-induced immune cell recruitment in these two model organs. The differential expression of certain receptors on mast cells of different tissues, notably tissue-specific expression patterns of integrins, complement receptors and MRGPRX2, could indicate that tissue environment-dependent factors skew mast cell-immune cell interactions, for example by regulating the expression of these receptors.

Keywords: MRGPRX2; Mast cells; cell heterogeneity; chemokines; chemotaxis; cytokines.

Figure 1

Heterogeneity in immune cell recrutiment. Exemplary differences between mucosal gut mast cells and connective tissue skin mast cells are shown. Differences in receptor expression include TLR4, P2X7, L1CAM, C5aR1, MRGPRX2 as well as integrin expression. Different mast cell mediators have been shown to be released with altered down stream consequences for immune cell recruitment in infection or inflammation.