Mast cell activation and degranulation pathways

Mast cell activation and degranulation pathways encompass the intracellular signaling networks that regulate the release of inflammatory mediators from mast cells in response to various stimuli [1.2.1, 1.3.2]. These pathways are primarily initiated through the high-affinity IgE receptor (FcεRI) upon allergen cross-linking, or through IgE-independent receptors such as MRGPRX2, KIT (CD117), and complement receptors [1.2.1, 1.3.3]. Activation leads to the rapid release of preformed mediators (e.g., histamine, tryptase) via degranulation, followed by the de novo synthesis of lipid mediators (e.g., leukotrienes, prostaglandins) and cytokines [1.4.3, 1.4.4]. These processes are central to the pathophysiology of allergic diseases, asthma, anaphylaxis, and mast cell activation syndrome (MCAS) [1.1.2, 1.2.2]. Therapeutic intervention targets various nodes within these pathways, including the neutralization of IgE, inhibition of signaling kinases like KIT and Syk, and the use of mast cell stabilizers to prevent mediator release [1.2.2, 1.3.1]. Drugs like omalizumab target the IgE-dependent pathway, while tyrosine kinase inhibitors like avapritinib target the KIT-mediated pathway [1.2.1, 1.2.3]. Mast cell stabilizers such as cromolyn sodium provide a broader, though less specific, inhibition of the degranulation process [1.1.1, 1.1.3]. Monitoring these pathways often involves measuring specific biomarkers like serum tryptase or urinary histamine metabolites [1.4.1, 1.4.3].

Other names

Mast cell activationMast cell degranulationIgE-mediated mast cell activationIgE-independent mast cell activationMast cell signaling pathways

Drugs targeting these pathways work by several distinct mechanisms: 1) neutralizing free IgE to prevent FcεRI-mediated activation (e.g., omalizumab); 2) inhibiting key intracellular signaling kinases such as KIT, Syk, or BTK (e.g., avapritinib, fostamatinib); 3) stabilizing the mast cell membrane to prevent the physical process of degranulation (e.g., cromolyn sodium); and 4) activating inhibitory receptors like Siglec-8 to suppress mast cell activity (e.g., lirentelimab) [1.2.1, 1.2.2, 1.3.1].