Cigarette
smoke is the principal risk factor for
chronic obstructive pulmonary disease (
COPD).
Multidrug resistance proteins, such as multidrug resistance-associated protein-1 (
MRP1),
P-glycoprotein (P-gp), and lung resistance-related
protein (LRP), may protect against oxidative stress and toxic compounds generated by cigarette smoking. Expression of
MRP1, P-gp, and LRP was evaluated in bronchial epithelium of two study groups of
COPD patients and their controls and was associated with disease status and smoking history. In study group 1,
MRP1, but not P-gp and LRP expression, was lower (p=0.029) in normal bronchial epithelium of
COPD patients (n=11) compared to healthy controls (n=8).
MRP1 expression was high in squamous metaplastic epithelium. When including expression in squamous metaplastic cells,
MRP1 was still lower in total bronchial epithelium in the
COPD group (p=0.038). In study group 2, expression of
MRP1, but not of P-gp and LRP, was lower (p=0.047) in lung tissue of (very) severe
COPD (n=10) vs mild to moderate
COPD (n=9) patients. In conclusion,
MRP1 expression was lower in bronchial biopsies of
COPD patients than of healthy controls and was also lower in patients with severe
COPD than with mild/moderate
COPD. Our findings indicate that diminished
MRP1 expression in normal bronchial epithelium is associated with
COPD. The exact role in
COPD pathogenesis is to be revealed by further functional studies.