Monday, June 2, 2014
Mechanisms underlying the neuronal based symptoms of allergy
People with allergies often present with symptoms that are the result of alterations in the nervous system in the organ in which the reaction occurs. Common neuronal symptoms include itchy eyes, sneezing, nasal congestion, rhinorrhea, cough, bronchoconstriction, airway mucus secretion, dysphagia, altered gastrointestinal motility, and itchy swollen skin. Mediators released during an allergic reaction interact with sensory nerves, altering the transmission of signals in the sympathetic and parasympathetic autonomic nerves. Undem and Taylor-Clark describe how the nervous system itself is altered in allergic disease either due to events occurring during critical periods of neuronal development or to persistent nerve stimulation (J Allergy Clin Immunol 2014; 133(6): 1521-1534).
Those that suffer from allergic rhinitis for example, more often react strongly by sneezing when stimulants are applied to the nasal mucosa compared to healthy controls. Considering sneezing is a parasympathetic reflex, it is not surprising that these allergic individuals are often more likely to have nasal allergic symptoms when exposed to smoke, irritants, and cold air. Similarly, in response to food allergy, immunological activation of mast cells in the gut is associated with alterations in neurotransmission. The authors detail the basic mechanisms of allergen-induced neuromodulation, highlighting the molecular interactions and phenotypic changes that occur.