Various techniques have been utilized historically to generate acute
pulmonary inflammation in the murine system. Crystalline
silica exposure results in acute
inflammation followed by
pulmonary fibrosis. Methods of exposure are varied in their techniques, as well as types of
anesthesia. Therefore, the current study sought to compare the effects of two major
anesthesia (
isoflurane and
ketamine) and three routes of instillation, intranasal (IN), intratracheal (IT), and trans-oral (TO), on markers of
inflammation. Mice were anesthetized with
isoflurane or
ketamine and instilled IN with
silica or
phosphate-buffered saline (PBS). Mice were sacrificed and lavaged after 3 days. To assess
inflammation, alveolar cells were assessed by cytospin and lavage fluid was analyzed for inflammatory
cytokines and total
protein. While all parameters were increased in
silica-exposed groups, regardless of
anesthesia type, there were significant increases in neutrophils and total
protein in mice anesthetized with
ketamine, compared to
isoflurane. In comparing instillation techniques, mice were anesthetized with
isoflurane and instilled IN, IT, or TO with
silica. Increases were observed in all parameters, except
tumor necrosis factor-alpha, following IT
silica instillation as compared to the IN and TO instillation groups. In addition, fluorescent
microsphere uptake by alveolar macrophages supported the notion that all methods of instillation were uniform, but IT had significantly greater dispersion. Taken together, these data show that each method of exposure tested generated significant
inflammation among the
silica groups, and any differences in parameters or techniques should be taken into consideration when developing an animal model to study
pulmonary diseases.