気道の粘液線毛クリアランスにおける遺伝と喫煙の影響

抄録

It has been reported that nonsmoking monozygotic twins have fairly similar bronchial mucociliary clearance. It is not clear, however, whether this similarity is affected by smoking. The author attempted to ascertain the genetic contribution to variation of smoking effect on bronchial mucociliary clearance and to demonstrate the regional difference of smoking effect within the lungs.
Forty-five healthy persons and 24 pairs of monozygotic twins were studied. Albumin aerosols (MMAD 4.2μ) labelled with ^99mTc (20mCi/2ml) were inhaled during rapid, shallow breathing (panting) with tidal volumes of approximately 100ml to enhance bronchial deposition. Clearance of deposited aerosols was quantified as a function of time (1.5 hours) using a gamma camera and computer system. The results were analyzed both for the whole right lung and for 3 concentric areas representing central, mid, and peripheral regions of the right lung.
Analysis of the intra-pair variances for total and peripheral clearance showed that the discordant smoking twins of 6 pairs differed from the concordant nonsmokers (5 pairs) and the concordant smokers (8 pairs), and that the intra-pair variances of the concordant nonsmokers and concordant smokers did not differ. In non-concordant smoking twins, smokers had a significantly faster clearance for the total lung and the peripheral region than the co-twin nonsmokers (p<0.01). Seven male heavy smokers (Brinkman index 664±176) had a significantly lower clearance in the central region than 8 male nonsmokers (p<0.05), while smokers had a significantly faster clearance in the peripheral region than nonsmokers (p<0.02). The ratios of activity within lung regions of the smokers and nonsmokers were compared using the linitial gamma camera image. There was no significant difference in indices of deposition pattern.
These results suggest that genetic factors play some roles in determining bronchial susceptibility to cigarette smoke with regard to bronchial mucociliary clearance and that smoking per se or factor (s) associated with smoking habits decelerates central mucociliary clearance while peripheral clearance is accelerated.