Pathology and Mechanism of Lung Toxicity Following Inhalation of Hair Spray in Rats

Abstract

In order to elucidate the pathology and mechanism of lung toxicity induced by chronic hairspray inhalation, male Wister rats 9 wk of age were exposed to a uniform concentration ofhair spray for up to 12 wk using a jet nebulizer. The aerosol concentration to which the ratswere exposed was about 7 g/m3. Differential cell counts in bronchoalveolar lavage fluid (BALF),the expression of several cytokines from alveolar macrophage using the reverse-transcriptionpolymerase chain reaction (RT-PCR) method, and histopathologic evaluation using a computeraidedgraphic analyzer (IBAS) were conducted 1, 4, 8, and 12wkafter exposure.Over the passageof time, neutrophils and macrophages increased in BALF, and neutrophils infiltrated in the lunginterstitium from the peribronchial interstitium to the alveolar septum. Alveolar macrophagesshowed increased expression of both the mRNA of tumor necrosis factor (TNF)-α and themRNA of the chemokines macrophage inflammatory protein 2 (MIP2) and cytokine-inducedneutrophil attractant (CINC). Fromthese findings, chronic inhalation of hair spray is consideredto induce at first intra-alveolar accumulation and activation of alveolar macrophages, followedby recruitment of neutrophils in the lung through the expression of proinflammatory cytokine,CINC, and MIP2, which cause predominantly neutrophilic inflammation in the lung.