Alterations in nonhuman primate (M. nemestrina) lung proteoglycans during normal development and acute hyaline membrane disease.

Proteoglycans (PGs) and lung hyaluronan (HA) are important components of the lung matrix both during normal development and in response to injury. We combined morphologic and biochemical techniques to study changes in PG and HA in a developmental series of Macaca nemestrina lungs ranging from 62% gestation to 3 mo post-term (n = 16), in adult lungs (n = 6), and from prematurely delivered, mechanically ventilated monkeys with hyaline membrane disease (HMD) (n = 7). Three groups of cuprolinic blue-positive (CuB) precipitates, identified by size, location, and susceptibility to enzyme digestion were found in lungs from all animals. Immature alveolar interstitium is characterized by loosely woven collagen bundles and an abundance of large (100 to 200 nm) stained filaments representing chondroitin sulfate proteoglycans (CSPGs). As maturation proceeds, the interstitial matrix appears increasingly organized, with large collagen bundles associated with 20 nm CuB-stained deposits (dermatan sulfate proteoglycans, DSPGs), and fewer large CSPGs. Fetal alveolar basement membrane contains CuB-stained heparin sulfate proteoglycans (HSPGs) (10 nm) scattered throughout. Lung matrix from animals with HMD appeared to have a disruption of the collagen-DSPG relationship, in addition to an enrichment in large CSPG. Complementary biochemical analysis of lung PGs and HA was done. Minced lung parenchyma was cultured with [3H]-glucosamine and [35S]-sulfate for 24 h; PGs and HA were extracted and analyzed. While PG synthesis during development tended to be highest at 80% gestation, animals with HMD showed greatly increased synthesis, approximately 2.5-fold higher than comparable fetal animals. In the developmental series, [3H]-glucosamine incorporation into HA was maximal at term, falling abruptly thereafter. HMD animals, however, showed a 2.3-fold increase over controls in net HA synthesis. Extracted PGs were separated according to buoyant density by dissociative cesium chloride density gradient ultracentrifugation. Two peaks of 35S-labeled PGs were separated from each density gradient fraction by chromatography on Sepharose CL-4B. A large CSPG was the principal PG eluting in the voiding volume, while the second broad peak (K(av) = 0.42) contained a mixed population of CSPG, DSPG, and HSPGs, the proportions of which varied with age. Both ultrastructural and biochemical analyses indicate that production of a large, high buoyant density CSPG predominates in fetal lung tissue, and diminishes with developmental age. Synthesis of large CSPG is greatly increased in lung explants from prematurely delivered animals with HMD.(ABSTRACT TRUNCATED AT 400 WORDS)