Non‐IgE mediated mast cell activation

Abstract

Mast cells (MCs) are innate immune cells that are scattered in tissues throughout the organism being particularly abundant at sites exposed to the environment such as the skin and mucosal surfaces. Generally known for their role in IgE-mediated allergies, they have also important functions in the maintenance of tissue integrity by constantly sensing their microenvironment for signals by inflammatory triggers that can comprise infectious agents, toxins, hormones, alarmins, metabolic states, etc. When triggered their main function is to release a whole set of inflammatory mediators, cytokines, chemokines, and lipid products. This allows them to organize the ensuing innate immune and inflammatory response in tight coordination with resident tissue cells, other rapidly recruited immune effector cells as well as the endocrine and exocrine systems of the body. To complete these tasks, MCs are endowed with a large repertoire of receptors allowing them to respond to multiple stimuli or directly interact with other cells. Here we review some of the receptors expressed on MCs (ie, receptors for Immunoglobulins, pattern recognition receptors, nuclear receptors, receptors for alarmins, and a variety of other receptors) and discuss their functional implication in the immune and inflammatory response focusing on non-IgE-mediated activation mechanisms.

The Theranostics Role of Mast Cells in the Pathophysiology of Rosacea

“…MCs express high-affinity IgE receptor (Fc epsilon RI or FcεRI), which can cross-link IgE with specific antigens and form IgE/FcεRI complexes, resulting in MC activation (22,23). Other pathways also stimulate MCs (24). For example, stimulation via the IgG and Ig-free light chains (FLC) can induce MC activation as can the combination of pathogen and pattern recognition receptors (PRRs) on MCs.…”

“…Once activated, the MCs can promote the release of different mediators and have a considerable effect on the pathophysiology of diverse inflammatory diseases (24). First, MCs can release histamine, tryptase, and chymase, which are preformed mediators stored in granules (degranulation) that initiate the allergic cascade.…”

What we know (and don't know) about the biology and functions of mast cells and basophils

“…Halova and coworkers have summarized what we have recently learned about the role and mechanisms of priming and modulating mast cells and their responses to different activators . Non‐IgE‐mediated mast cell activation is the topic of the contribution by Redegeld et al . They focus on the role and relevance of pattern recognition receptors, nuclear receptors, and receptors for alarmins in IgE‐independent activation and subsequent immunological and inflammatory responses.…”

“…learned about the role and mechanisms of priming and modulating mast cells and their responses to different activators. 5 Non-IgE-mediated mast cell activation is the topic of the contribution by Redegeld et al 6 They focus on the role and relevance of pattern recognition receptors, DOI: 10.1111/imr.12645…”

The Role of Mast Cells in IgE-Independent Lung Diseases

“…Expression of integrins, mainly α4β7 and α4β1, on MCps helps them traffic from the circulation into the lung by binding to vascular cell adhesion molecule-1 (VCAM-1) expressed on the endothelium [2]. MCps complete their final stage of differentiation to functional MCs under the influence of growth factors particularly stem cell factor (SCF) [3]. In addition to SCF, there are other cytokines that contribute to the growth and differentiation of MCps to functional mature MCs including transforming growth factor (TGF)β, nerve growth factor (NGF), interleukin (IL)-3, IL-4, IL-9, and IL-33 [2].…”