 To study the impact of LCPUFA n-3 on MUC5B expression mRNA level by RT-PCR collected in airway epithelial cells obtained by nasal brushing. The secondary aim is to assess : MUC1, MUC2, MUC4, MUC5AC, MUC7 expression mRNA level in airway epithelial cells obtained by nasal brushing; Lund-Kennedy score; TNK-alpha, IL-6, IL-8 in blood plasma. This study is a double parallel, controlled double blind, randomized clinical trial : LCPUFA n-3 1 gday vs placebo for 6 weeks. 30 subjects will be included in this study. Primary and secondary study end point will be assessed two times: before randomization and after 60 days of treatment. 