Figure 4.

GM-CSF is produced by lung epithelial cells in a MyD88 dependent manner. (a) C57BL/6 mice were intranasally treated with CRA. Two hours later, lung tissue was collected and mRNA expression of GM-CSF was determined by qPCR. Expression values are relative to PBS control samples and normalized to the housekeeping gene GAPDH. BAL fluid was also collected and GM-CSF protein level was measured by ELISA. Data represent combined data of two independent experiments, mean ± SEM (n = 7–15 mice per group). (b) SPC-Cre/Myd88^fl/fl and Myd88^fl/fl mice were intranasally treated with CRA. Two hours later, lung tissue was collected and mRNA expression of GM-CSF was determined by qPCR. Data represent combined data of two independent experiments, mean ± SEM (n = 4–10 mice per group). (c) Tracheas from C57BL/6 and Myd88−/− mice were harvested and primary epithelial cells were cultured at air-liquid interface. Cells were exposed to 15 μg of CRA or PBS for 24 hours and medium from the basal compartment was collected. GM-CSF levels were measured by ELISA. Data represent mean ± SEM of one experiment and are representative of two independent experiments. Comparisons were made using unpaired Student’s t test. * p < 0.05, ** p < 0.01, *** p < 0.001.