COMBINING HISTOLOGY AND BIOCHEMICAL MEASUREMENTS OF CONNECTIVE TISSUE COMPONENTS IN SMALL SAMPLES OF LUNG: APPLICATION TO BLEOMYCIN-INDUCED FIBROSIS IN THE MOUSE

Abstract

Bleomycin-induced lung injury in mice was used to illustrate the plausibility of quantitating changes in elastin or protein concentration in histologically defined regions of mouse lungs. Mice were instilled by either the intranasal or intratracheal route with varying levels of bleomycin and the lungs were removed and fixed under pressure for histology and analysis. Histological sections that bracketed a defined volume of tissue was used for biochemical analysis and was limited to the alveolar region of the lung. Our studies showed that the intranasal method of instillation was as effective as the intratracheal method for inducing fibrosis. Even though distribution to the 4 major lobes of the lung was fairly uniform, there was no consistency in the degree of fibrosis between the various lobes of the same animal. The most dramatic change in biochemical parameters was protein concentration, which increased over 10-fold in some fibrotic lungs compared to normal lungs, whereas desmosine concentration increased up to 5-fold. Fibrosis scores agreed well with desmosine concentration, except with moderate desmosine increases where histologically defined fibrosis was not observed. The experiments illustrate the feasibility and desirability of comparing histology and biochemical analysis on the same fixed lung sample. elastin desmosine lung fibrosis