Relation of epidermal growth factor receptor expression to mucus hypersecretion in diffuse panbronchiolitis.
OBJECTIVE
Diffuse panbronchiolitis (DPB) is a hypersecretory airway disease, and the mechanism of mucus hypersecretion in DPB is poorly understood. Moreover, mucin synthesis in the airways has been reported to be regulated by neutrophilic inflammation-induced epidermal growth factor receptor (EGFR) expression, and the degranulation of goblet cells is known to be mediated by neutrophilic elastase. In this study, we examined the relationship between EGFR expression in the bronchiolar epithelium with neutrophilic inflammation and mucus hypersecretion in the tissues of DPB patients.


METHODS
The tissue specimens of 13 DPB patients and 6 healthy control subjects were examined by alcian blue/periodic acid-Schiff (AB/PAS) staining for mucous glycoconjugates, and by immunohistochemical staining for MUC5AC, EGFR, tumor necrosis factor-alpha, and CD16 on neutrophils.


RESULTS
Neutrophilic inflammation was significantly higher in the tissue of DPB patients than in that of control subjects (p = 0.002). In the bronchiolar epithelium, goblet cell metaplasia, by AB/PAS staining and mucin MUC5AC expression, was significantly higher than that in control subjects (p = 0.001 and p = 0.002, respectively). In addition, the morphometric quantification of intraluminal mucus secretion showed that the areas of the bronchiolar lumen occupied by mucus secretion were significantly increased in the tissue of DPB patients (p = 0.001), suggesting goblet cell degranulation. EGFR expression was observed in the bronchiolar epithelium of DPB patients, but not in that of control subjects.


CONCLUSIONS
In DPB, we suggest that mucus hypersecretion due to goblet cell metaplasia is closely associated with neutrophilic inflammation and the expression of EGFR. The study also shows that intraluminal secretion due to the degranulation of goblet cells degranulation is related to neutrophilic inflammation.
Kim
Je-Hyeong
JH
Pulmonary Division, Department of Internal Medicine, Korea University Guro Hospital, 97 Gurodong-gil, Guro-gu, Seoul, Korea.
Jung
Ki-Hwan
KH
Han
Joung-Ho
JH
Shim
Jae-Jeong
JJ
In
Kwang-Ho
KH
Kang
Kyung-Ho
KH
Yoo
Se-Hwa
SH
D000328:Adult; D001989:Bronchiolitis Obliterans / Q000473:pathology / Q000503:physiopathology*; D066246:ErbB Receptors / Q000502:physiology*; D005260:Female; D020397:Goblet Cells / Q000473:pathology / Q000502:physiology; D006801:Humans; D018836:Inflammation Mediators / Q000378:metabolism; D007958:Leukocyte Count; D008297:Male; D008679:Metaplasia; D008875:Middle Aged; D055271:Mucin 5AC; D009077:Mucins / Q000378:metabolism; D009093:Mucus / Q000378:metabolism*; D009504:Neutrophils / Q000502:physiology; D020545:Respiratory Mucosa / Q000473:pathology / Q000503:physiopathology; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
D018836:Inflammation Mediators; C524678:MUC5AC protein, human; D055271:Mucin 5AC; D009077:Mucins; D014409:Tumor Necrosis Factor-alpha; D066246:ErbB Receptors