Evaluation of epithelial mesenchymal transition in patients with chronic obstructive pulmonary disease

Abstract

BackgroundThe reticular basement membrane (Rbm) in smokers and especially smokers with COPD is fragmented with "clefts" containing cells staining for the collagenase matrix-metalloproteinase-9 (MMP-9) and fibroblast protein, S100A4. These cells are also present in the basal epithelium. Such changes are likely hallmarks of epithelial mesenchymal transition (EMT). We aimed to confirm the epithelial origin of these Rbm cells, and to exclude potential confounding by infiltrating inflammatory cells.MethodsEndobronchial biopsy sections from 17 COPD current smokers, with documented Rbm splitting and cellularity were stained for neutrophil elastase (neutrophil marker), CD68 (macrophage/mature fibroblasts), CD4+/CD8+ T lymphocytes, CD19 (B-cells), CD11c (dendritic cells/inflammatory cells), and S100 (Langerhans cells). The number of cells in the Rbm and epithelium staining for these "inflammatory" cell markers were then compared to numbers staining for S100A4, "a documented EMT epitope". Slides were double stained for S100A4 and cytokeratin(s).ResultsIn the basal epithelium significantly more cells stained for S100A4 compared to infiltrating macrophages, fibroblasts or immune cells: median, 26 (21.3 - 37.3) versus 0 (0 - 9.6) per mm, p < 0.003. Markedly more S100A4 staining cells were also observed in the Rbm compared to infiltrating macrophages, neutrophils, fibroblasts or immune cells or any sub-type: 58 (37.3 - 92.6) versus 0 (0 - 4.8) cells/mm Rbm, p < 0.003. Cells in the basal epithelium 26 (21.3 - 37.3) per mm) and Rbm (5.9 (2.3 - 13.8) per mm) frequently double stained for both cytokeratin and S100A4.ConclusionsThese data provide additional support for active EMT in COPD airways.

Imprinting of the COPD airway epithelium for dedifferentiation and mesenchymal transition

“…EMT in conducting airways was shown in post-transplant bronchiolitis [25], as well as in chronic rhino-sinusitis [26]. In COPD, SOHAL and colleagues [12,13] observed in large airways from COPD patients the presence of clefts within the RBM containing S100A4/vimentin/ matrix metallopeptidase (MMP)-9 positive epithelial cells, presumably migrating from the surface epithelium to the lamina propria. MILARA et al [14] recently reported EMT features in small airways of smokers and COPD patients and in undifferentiated (submerged) primary broncho-epithelial cells from COPD patients.…”

“…EMT participates in normal lung biology during development (airway branching) and repair, but is also observed during cancer progression and metastasis [10]. While alveolar EMT has been reported in lung fibrosis [11], three recent studies suggest that EMT also occurs in COPD airways [12][13][14]. However, the underlying mechanisms and the functional consequences of EMT in the conducting airways from COPD patients remain unclear.…”

Epithelial to mesenchymal transition is increased in patients with COPD and induced by cigarette smoke

“…In addition, evidence for EMT in the large airways of smokers and patients with COPD has been suggested by Sohal and colleagues, since cells included in the reticular basement membrane of large airways showed EMT markers 13. However, whether EMT is present in the small airways of smokers and patients with COPD and whether cigarette smoke directly induces EMT in differentiated HBECs remains to be elucidated.…”

Epithelial mesenchymal transition (EMT) in small airways of COPD patients

“…In a follow-up paper3 we excluded such confounding. Further, our study illustrated that cells in the basal epithelium, and reticular basement membrane (Rbm) in smokers/COPD double-stain for cytokeratin-(s) and the ‘EMT marker’ S100A4, confirming a likely epithelial origin of these cells.…”