MUC5AC and lung disorder: To address this hypothesis, we examined the expression of multiple host genes: inflammatory cytokines (IL-6, IL-17, TNF-alpha, IL-4 and IL-13), a mucin production gene (muc5AC), indoleamine 2,3-dioxytenase (IDO1; associated with impaired mucosal immunity and increased microbial translocation), and matrix metalloproteinase-9 (MMP9; abundant in lung diseases and involved in the breakdown of extracellular matrix).