A consistent body of research has linked
cystic fibrosis (CF) with variations in the tissue and fluid content in a number of
lipid molecules. However, little is known about the spatial localization of those variations. We have recently applied TOF-SIMS mass spectrometry imaging to detect differential
lipid signatures at the colon epithelium between normal and cftr-/- mice. In the present work we have used this technology to investigate potential differences in the spatial distribution of
lipids due to Pseudomonas aeruginosa (P.a.)
infection in mouse lung expressing or not cftr. Wild-type and exon 10 cftr knockout mice were subjected to intranasal
infection with a clinical strain of P.a. Lung cryosections from infected and non-infected mice were subjected to cluster TOF-SIMS analysis in the negative ion mode. We observed a highly specific localization of a phosphoinositol fragment ion at m/z 299.1 in bronchial epithelium. Using this ion to delineate a region of interest, we studied the relative abundance of
ions below m/z 1500. We found a significant increase in m/z 465.4 (identified as
cholesteryl sulfate) in cftr-/- epithelium and in response to
bacterial infection, as well as a decrease in most carboxylic
ions. In conclusion, the m/z 299.1 ion can be used as a marker of bronchial epithelium, where P.a.
infection leads to increased presence of
cholesteryl sulfate in this tissue. TOF-SIMS imaging reveals as a valuable tool for the study of respiratory epithelium.