二氧化钛粉尘致犬肺的病理组织学改变

PATHOGENIC EFFECTS OF TITANIUM DIOXIDE DUST ON THE LUNG OF DOGS——A HISTOPATHOLOGICAL AND ULTRASTRUCTURAL STUDY

作者对家犬进行气管二氧化钛染尘,9～15个月后,光镜观察:粉尘主要沉积在呼吸细支气管及其周围肺泡腔、肺池壁内,粉尘灶周成纤维细胞增生明显。电镜观察:尘灶周正常肺泡结构破坏,Ⅰ型肺泡上皮细胞消失,代之以增生的Ⅱ型肺泡上皮细胞;上皮下基底膜显著增厚,间质内成纤维细胞增生及成束胶原纤维产生。结果表明二氧化钛粉尘对犬肺具有轻度致纤维化作用。

Titanium dioxide (TiO_2) dust has gen-erally been regarded as a 'nuisance dust' inexperimental animals and men. In this ex-periment, 16 dogs were exposed intratrache-ally to TiO_2 dust for 9-15 months. Thescanning electron microscopy with energydispersive analysis of X-ray (SEM-EDAX),performed to identify the elemental compo-sition of dust particles used in the studyand in the focal lesions of the lungs, show-ed that dust particles were nearly puretitanium. Dust in the lung deposited main-ly in the respiratory bronchioles and adja-cent alveoli, with many alveoli filled bycompacted dust particles. The pulmonaryresponses consisted of slight alveolitis, cen-trilobular emphysema, focal collapse ofalveoli, and fibroblast hyperplasia with afew collagen fibres surrounding some of theTiO_2-dust foci. Electron microscopically, manyalveolar macrophages with intact nuclei con-rained a great amount of dust particles intheir lysosomes, and in the dust foci, mostof type Ⅰ pneumocytes disappeared and typeⅡ pneumocytes showed hyperplasia. Thealveolar subepithelial basement membranewere markedly thickened and bundles ofcollagen fibres were formed in the inter-stice. These findings suggest that TiO_2 dustis one of the sorts which probably inducemild lung fibrosis in case a large amount isdeposited in the lung tissue.