Acrolein Stimulates Overexpression Of MUC5AC And MUC2 In Rat Airways Through The Activation Of NF-κB

Objective The purpose of this study was to investigate the mechanism of airways mucus hypersecretion after acrolein inhalation and NF- κ B inhibitor intervention: 1.To explore the role of NF— κ B in the expression of MUC5AC and MUC2 in rat airways ; 2. To explore the correlation of IL-8 and TNF- α with overexpression of MUC5AC and MUC2 by detecting IL-8 and TNF- α in BAL fluid.Methods The rat airways mucus hypersecretion model was established by aerosol acrolein inhalation. Rats were exposed to acrolein alone (3.0 parts/million, 6h/day, together 12days), or simultaneously intraperitonealy injected with CAPE (caffeic acid phenethyl ester) (30mg/kg ,qod). The expression of MUC5AC mRNA 和 MUC2 mRNA in trachea and lung samples was detected by RT-PCR, and PCR products were photographed by agarose gel electrophoresis, and quantitated by densitometry ; The proteins expression of MUC5AC, MUC2, NF- κ B and I k B were detected by immunohistochemical staining. The average optical density of positive staining MUC5AC, MUC2, NF- κ B and IκB was determined by image analysis technique and gray scale scanning; Cells counting and classification were carried out, and the concentrations of IL-8and TNF- a in BALF were detected by ELISA .Results At 12 days of stimulation with acrolein ,the expression of MUC5AC mRNA fP MUC2 mRNA were obviously up-regulated in tracheal and lung samples in a time-dependent manner comparing with that in control group (P.< 0.05 or P < 0.01) .The expression of MUC5AC mRNA fP MUC2 mRNA were decreased after the treatment with CAPE(P < 0.05 or P < 0.01). Immunocytochemical staining showed that positive MUC5AC and MUC2 staining was identified in acrolein-induced mucus hypersecretion rats, comparing with a weak positive staining of MUC5AC and MUC2 in control rats (P < 0.05 or P < 0.01) .The inhibitor of NF-k B CAPE significantly reduced MUC5AC and MUC2 staining (P < 0.05 or P < 0.01). Moreover the positive staining rate of NF-k B increased (P < 0.05 or P < 0.01) , meanwhile Ik B occurred degradation in the cytoplasm (P < 0.05 or P < 0.01) in acrolein group, which were positively correlated with the increased expression of MUC5AC and MUC2( tracheal MUC5AC r=0.778> lung MUC5AC r=0.84K lung MUC2 r=0.798; P<0.01).The treatment with CAPE reduced the positive staining of NF- k B (P < 0.05 or P < 0.01) , increased I k B staining (P < 0.05 or P < 0.01) .Acrolein inhalation increased IL-8 and TNF- a release in BALF compared with control group (P < 0.05 or P < 0.01) , whereas releasing weaken after Inhibition (P < 0.05 or P < 0.01) .CAPE decreased the release of IL-8 and TNF- a in BALF.Conclusion NF-kB, MUC5AC and MUC2 show overexpression in acrolein-induced rat airways mucus hypersecretion. The over- expression of MUC5AC and MUC2 in rat airways epithelia may be though the activation of NF- k B .The inhibitor of NF- k B CAPE may reduce airways mucussecretion in rat airways stimulated with acrolein. IL-8 and TNF- a had participated ,at least in part, the hypersecretion of MUC5AC and MUC2.