Background: Local hyperthermia reduces mast cell degranulation, the severity of acute lung injury, and exercise-induced asthma and decreases symptoms of rhinitis. We have investigated the effect of local hyperthermia on mast cell degranulation and symptom generation in allergic rhinitis to assess its effect and mechanism of action within the nose.
Methods: In a randomized, double-blind, placebo-controlled, crossover study, 10 subjects with rhinitis were treated for 30 minutes with local hyperthermia or placebo, which was followed 30 minutes later by nasal allergen challenge. During the first two visits nasal lavages were performed to assess vascular leakage and mediator release. During the last two visits nasal airway resistance, the number of sneezes, and mucus secretion were monitored.
Results: Local hyperthermia significantly reduced both nasal airway resistance (p < 0.05) and vascular leakage (p < 0.02) but had no significant effect on the number of sneezes, on mucus secretion, or on tryptase release.
Conclusion: Local hyperthermia reduces allergen-provoked nasal blockage and vascular leakage but has no effect on sneezing, rhinorrhea, or tryptase release. Nasal blockage occurs predominantly via newly formed lipid mediators and kinins, whereas sneezing and rhinorrhea occur predominantly via preformed mediators. We propose that local hyperthermia inhibits newly formed mediator production or release or reduces the sensitivity of the vasculature to inflammatory mediators in general. Further investigation into the mechanisms and potential uses of local hyperthermia is warranted.