The effect of topical sodium cromoglycate on intranasal histamine challenge in allergic rhinitis

Role of allergy in rhinosinusitis

PURPOSE OF REVIEW

Allergic rhinitis and rhinosinusitis are common diseases occurring in both children and adults that consume enormous amounts of health care dollars. In addition to its own costs, allergic rhinitis is considered a major predisposing factor for the development of rhinosinusitis. Whereas many authors suggest a clinical association between these two diseases, the mechanism of how allergic rhinitis predisposes to rhinosinusitis or affects the course of rhinosinusitis remains unclear.

RECENT FINDINGS

Limited progress has been made in understanding the pathophysiologic mechanism involved in the interaction. Progress in immunologic technique emphasizes the importance of inflammatory cells, especially eosinophils, mast cells, and T lymphocytes, and their mediators. Some authors have proposed a role for neurogenic pathways, whereas others have focused on systemic involvement. Little progress has been made in intervention studies that support the importance of allergic rhinitis in altering the course of acute or chronic rhinosinusitis.

SUMMARY

This paper reviews the limited new literature available to update knowledge that supports the association of allergic rhinitis with rhinosinusitis, mechanisms potentially underlying the association, and implications of this knowledge for therapy.

Effect of topical nasal pharmaceuticals on sodium and chloride transport by human airway epithelia

The human airway epithelium lines the respiratory tract from the nasal mucosa to the bronchioles. Electrolyte transport by these epithelia is crucial in maintaining the appropriate volume and salt composition of the airway surface fluid. When this epithelium becomes functionally impaired, the airways are more prone to respiratory infections. We studied the effect of six common topical agents that are commonly used to treat rhinorrhea and nasal inflammation on the transepithelial resistance, sodium, and chloride transport of primary cultures of human airway epithelia grown at the air-liquid interface. The pharmaceuticals fluticasone propionate, cromolyn sodium, ipratropium bromide, azelastine, oxymetazoline, and normal saline were used and the electrical function of the epithelia was studied in Ussing chambers. Azelastin and ipratropium bromide-treated epithelia were found to have a significant decrease in transepithelial resistance. Both normal saline and fluticasone propionate resulted in significant increases in amiloride-sensitive short circuit currents that reflect sodium transport. Finally, normal saline resulted in a significant increase in bumetanide-sensitive short circuit current that reflects chloride transport across the epithelia. The data presented may explain a mechanism by which some topical pharmaceuticals help reduce rhinorrhea, and may point to some unwanted side effects of some pharmaceuticals on the electrolyte transport of the airway epithelia. In summary, several of the common topical nasal agents alter the electrolyte transport of the nasal airway epithelia. The in vivo significance of these findings is to be determined.

Nonspecific nasal mucosal reactivity, expressed as changes in nasal airway resistance after bilateral saline provocation

When using intranasal provocation tests in diagnosing nasal allergy or other hyperreactivity, it is essential to know which part of the reaction is caused by some nonspecific stimulus. The purpose of this study is to evaluate nonspecific nasal reactions of patients with chronic nonallergic perennial rhinitis as well as normal controls. The provocations were made bilaterally with normal saline solution (0.9% sodium chloride), and the changes in the nasal resistance were recorded by active anterior rhinomanometry. There was no significant difference between the chronic rhinitis patients and the normal controls. However, the individual variations were large. We conclude that a change of +/- 100-150% in the unilateral nasal resistance can be caused by a nonspecific reactivity.