Effects of matrix metalloproteinase inhibitor on LPS-induced goblet cell metaplasia

Abstract

Bacterial infections of the lung are known to induce inflammatory responses, which lead to mucus hypersecretion. Moreover, mucin synthesis in the airways has been reported to be regulated by neutrophilic inflammation-induced epidermal growth factor receptor (EGFR) expression and its activation. Furthermore, matrix metalloproteinases (MMPs), especially MMP-9, have been reported to promote the transmigration of activated neutrophils. In this study, we investigated the associations between lipopolysaccharide (LPS)-induced goblet cell (GC) metaplasia and EGFR expression and the effects of MMP inhibitor (MMPI). Various concentrations of LPS were instilled into the tracheas of pathogen-free Sprague-Dawley rats, and airways were examined at different times after LPS instillation. To examine the role of MMP-9, we treated rats 3 days before LPS instillation and daily thereafter with MMPI. Neutrophilic infiltration, Alcian blue/periodic acid-Schiff (AB/PAS) staining, and immunohistochemical staining for MUC5AC, EGFR, and MMP-9 were performed. The instillation of LPS increased AB/PAS and MUC5AC staining in time- and dose-dependent manners, and treatment with MMPI significantly prevented GC metaplasia. The instillation of LPS into the trachea also induced neutrophilic infiltration and EGFR and MMP-9 expression in the airway epithelium, and MMPI was found to significantly prevent neutrophil recruitment, GC metaplasia, and EGFR and MMP-9 expression. This study demonstrates that the MMP-9 and EGFR cascades are associated with LPS-induced mucus hypersecretion.

Macrophages are related to goblet cell hyperplasia and induce MUC5B but not MUC5AC in human bronchus epithelial cells

“…Single intra-tracheal administration of LPS from P. aeroginosa or E. coli in rat and mouse has been extensively used to induce mucus production. 35,[40][41][42] In the present study, rats treated with a single intra-tracheal dose of LPS from E. coli show increased number of goblet cells only in bronchiolar areas proximal and distal to the FAE, but not in terminal bronchioles. We did not investigate if increased number of goblet cells was associated with mucin changes in bronchoalveolar lavage, because airway mucin secretion was out of the scope of this study.…”

“…Of note, augmented epithelial cell proliferation equivalent to the number of goblet cells in terminal bronchioles confirmed the presence of GCH and not metaplasia, as proposed by others. 35 A differential distribution of goblet cells and proliferative epithelial cells indicate the relevance of studying specific anatomical compartments. It is also important to highlight that mucin induction by a single intra-tracheal administration of LPS in mouse and rat is different, because the upregulation of mucin markers in mouse occurs at day 7, 42 and not 48 h after treatment like in rats.…”

“…Moreover, we did not have bronchoalveolar fluids to examine luminal inflammatory cells as performed in other studies. 35,36 An interaction between the apical pole of the airway epithelium and luminal microbial antigens may induce the release of cytokines that trigger GCH via local stimulation or recruitment of additional inflammatory cells. 38 However, the close vicinity detected in our LPS model between bronchiole goblet cells and interstitial macrophages allow us to hypothesize that-beside any direct cell-cell interaction-soluble factors released by those macrophages may contribute also to modulate via a basolateral pathway the phenotype of bronchiolar goblet cells.…”

“…We used PAS, MUC5AC, and the lectin Ulex Europaeus Agglutinin I (UEA-1) as mucin markers, which have been extensively used to study airway goblet cells in rat. 35,36 Immune markers were assessed in inflamed and non-inflamed areas from bronchioles. Goblet cells and proliferating Ki-67 þ epithelial cells were quantified by counting stained cells per 50 epithelial nuclei in three different fields of  400 magnification, excluding unspecific reactions and structures lacking a nucleus, whereas CD68 quantification was performed by percentage of stained area per  400 field due to the patchy pattern of this marker and difficulties identifying single CD68 þ cells.…”

Matrix metalloproteinases in COPD

“…Other workers have shown that mucin production induced by acrolein-fog or LPS inflammatory stimuli appears to be related to MMP-9 activity [129][130][131], but the relationship of such models to smoke-induced lesions is uncertain.…”