A new look at the pathogenesis of the meconium aspiration syndrome: a role for fetal pancreatic proteolytic enzymes in epithelial cell detachment.
We hypothesized that fetal pancreatic digestive enzymes play a role in the lung damage after meconium aspiration. We studied the effect of meconium on the A549 alveolar epithelial cell line. The exposure of the cells to 0.5 to 5% meconium resulted in significant disruption of connections between A549 cells and caused dose-dependent cell detachment, without signs of cell death. A protease inhibitor cocktail prevented the A549 cell detachment induced by meconium. After the exposure to 2.5% meconium, a protective effect was quantified by measuring light absorbance by gentian violet stain of still attached cells. The protease inhibitor cocktail and chymostatin showed significant protective effects, increasing the number of attached cells by 135 and 123%, respectively (p < 0.05). Other individual protease inhibitors tested in the detachment assay (AEBSF, leupeptin, E-64, aprotinin, benzamidine, phosphamidon, and aminohexanoic acid) did not offer statistically significant protection. These results afford a new perspective on the pathophysiology of meconium aspiration syndrome (MAS). We speculate that disruption of intercellular connections and cell detachment from the basement membrane are key events in the pathology associated with MAS. The observed protective effects of protease inhibitors suggest that they may be useful in the treatment and/or prophylaxis of MAS.
Ivanov
Vadim A
VA
Departments of Pediatrics/Neonatology, Michigan State University, East Lansing, MI 48823, USA. vadim2@earthlink.net
Gewolb
Ira H
IH
Uhal
Bruce D
BD
D000704:Analysis of Variance; D002448:Cell Adhesion / Q000187:drug effects / Q000502:physiology*; D002460:Cell Line; D004847:Epithelial Cells / Q000187:drug effects / Q000502:physiology*; D005840:Gentian Violet; D006801:Humans; D066298:In Vitro Techniques; D007231:Infant, Newborn; D008470:Meconium / Q000201:enzymology*; D008471:Meconium Aspiration Syndrome / Q000209:etiology* / Q000503:physiopathology*; D008858:Microscopy, Phase-Contrast; D009842:Oligopeptides / Q000494:pharmacology; D010447:Peptide Hydrolases / Q000494:pharmacology*; D011480:Protease Inhibitors / Q000494:pharmacology
D009842:Oligopeptides; D011480:Protease Inhibitors; C002101:chymostatin; D010447:Peptide Hydrolases; D005840:Gentian Violet