Neisseria lactamica attenuates TLR-1/2-induced cytokine responses in nasopharyngeal epithelial cells using PPAR-γ

P>The upper respiratory tract commensal Neisseria lactamica (Nlac) induces protective humoral immunity against pathogenic Nmen serogoup B (Nmen), but whether it also affords anti-inflammatory mucosal protection, as reported for several gut commensals, has not been investigated. Here we demonstrate for the first time that Nlac weakly induces inflammatory responses compared with Nmen in the nasopharyngeal epithelial cell line, Detroit 562, and that Nlac achieves this by attenuation of secretory cytokine (TNF-alpha and IL-6) and to a lesser extent chemokine (IL-8 and RANTES) responses. Culture of Detroit cells with Nlac inhibited the induction of cytokine-chemokine mRNA by Nmen, reduced Nmen-induced NF-kappa beta activity and increased constitutive PPAR-gamma protein expression. Pretreatment of Detroit cells with a PPAR-gamma antagonist abrogated the attenuation of inflammatory IL-6 by Nlac, as did heat-killing of the organisms and preventing their invasion with cytochalasin D. Inflammatory responses from Detroit cells were readily attenuated by Nlac following stimulation with pathogenic Nmen but more specifically following stimulation with the TLR-1/2 agonist Pam3Cys and pro-inflammatory cytokines (IL-1 beta, TNF-alpha) but not LTA or LPS. These results indicate that Nlac plays an important role in suppressing pathogen-induced inflammation in the nasopharyngeal mucosa, mediated through TLR-1/2 stimulation, by activating PPAR-gamma and inhibiting NF-kappa beta activity.