The effects of physical exercise and smoking habits on the expression of SPLUNC1 in nasal lavage fluids from allergic rhinitis subjects.

Objective: Palate lung nasal epithelial clone (PLUNC) is a family of proteins, which are proposed to participate in the innate immune defense against infections in the upper aero-digestive tract. The aim of this study was to investigate the expression of SPLUNC1 in allergic rhinitis subjects with considerations taken to the mucosal function and smoking habits.

Methods: The participants, recruited from a cohort followed from infancy, were re-examined at the age of 18 years regarding allergy development. Based on medical histories and skin prick tests the participants were classified into groups with persistent allergic rhinitis (n=18), intermittent allergic rhinitis (n = 8) and healthy controls (n = 13). Seven subjects (3, 2 and 2 in each group, respectively) reported smoking habits. The SPLUNC1 levels in nasal lavage fluids were analyzed by Western blot. Changes in the volume of the proper nasal cavity before and after physical exercise (Vol2(increase)) were analyzed by acoustic rhinometry.

Results: Compared to the control group the SPLUNC1 level was significantly lower in the persistent allergy group (3.8 ± 3.4 OD vs. 1.3 ± 1.5 OD; p = 0.02), but not in the intermittent allergy group without current exposure to allergens (3.6 ± 4.7 OD). No differences were found in Vol2(increase) between any of the allergy groups and controls. In smokers Vol2(increase) was significantly reduced (p < 0.01) and the SPLUNC1 levels were lower compared to non-smokers. A significant correlation was found between SPLUNC1 and Vol2(increase) (p < 0.01; r = 0.53) in non-smokers.

Conclusions: Current allergen exposure has an impact on SPLUNC1 expression in nasal lavage fluid, why allergy ought to be considered in study populations where analyses of SPLUNC1 levels are included in the reports. The normal nasal decongestion after exercise was not affected by allergy in contrast to smoking habits. The correlation between SPLUNC1 levels and Vol2(increase) in non-smokers may indicate involvement of SPLUNC1in the regulation of the normal function of the nasal mucosa. Complementary studies are needed to confirm the smoke-related reduction of SPLUNC1 expression and to analyze the possible participation of SPLUNC1 in the nasal mucosa regulation.