Pathophysiological Drivers of Mast Cell Activation Syndrome and Implications for Treatment

Mast Cell Activation Syndrome (MCAS) is an underrecognized multisystem disorder causing nonspecific and diverse symptoms, making it difficult for clinicians to diagnose and treat. This comprehensive review provides an overview of the signs and symptoms of MCAS while investigating the known pathophysiological signaling pathways and mediators that contribute to mast cell (MC) dysregulation. Unraveling the mechanisms of MC activation is essential for elucidating the underlying disease and exploring techniques to improve quality of life. Immunoglobulin E (IgE)- and non-IgE-mediated pathways are emphasized in addition to the various intracellular signaling like PI3K/Akt/mTOR, RAS/MAPK, and JAK/STAT that play pivotal roles in the amplification of MC activation and dysregulation. After activation of intracellular pathways, MC degranulation releases mediators, notably histamine, tryptase, heparin, leukotrienes, prostaglandins, and cytokines, thus facilitating further aberrant regulation. Finally, with a thorough understanding of these advanced molecular processes, there are numerous opportunities to be able to apply specialized inhibitors and novel therapies for treating MCAS. With antihistamines remaining the most well-established first-line treatment, the goal is to continue strengthening research in the field through education on the immunology of MCAS and to encourage discoveries that improve diagnostic biomarkers and therapeutic strategies.