Cm. Castro et al., Attenuation of pulmonary neuroendocrine differentiation in mice lacking Clara cell secretory protein, LAB INV, 80(10), 2000, pp. 1533-1540
During development and injury, pulmonary neuroendocrine (NE) cells may tran
siently express Clara cell 10 kD protein (CC10), a major product of the non
ciliated progenitor cells for normal and neoplastic airway epithelia sugges
ting a close relationship between the cells. To assess the role of CC10 dur
ing NE differentiation, we studied CC10-deficient mouse lungs by immunohist
ochemistry and digital imaging. The knockout model revealed a lack of the d
isrupted gene product in the lung. Because NE cells, which occur as solitar
y cells or in neuroepithelial bodies (NEBS), comprise less than 1% of airwa
y epithelia, we counted foci positive for each of the three NE markers-syna
ptophysin, calcitonin gene-related peptide (CGRP), and protein gene product
(PGP) 9.5-and developed a method to analyze numerous airways in serial sec
tions. Digitized images of slides were segmented with Photoshop imaging sof
tware. The length of airway epithelium and total section areas were then me
asured using MetaMorph image analysis software. A comparable range of NE fo
ci was observed regardless of CC10 expression patterns with all three marke
rs, suggesting that CC10 is not critical for NE ontogenesis. However, discr
imination according to size revealed that wild-type lungs harbored 30% to 4
0% greater synaptophysin- and CGRP-containing NEBs relative to CC10 deficie
nt lungs. We posit that an attenuation of pulmonary NE differentiation affl
icts the CC10-deficient state. Our imaging application greatly facilitates
the acquisition and analysis of complex structures such as the lung and pro
mises to be a widely applicable technique for assessments of tissue section
s.