Meconium proteases and antiproteases as a potential source of biomarkers for the assessment of the intrauterine environment of the fetus.

BACKGROUND A protease-antiprotease balance is required to maintain the homeostasis of the intrauterine environment in which the fetus develops. Proteases and antiproteases accumulate in meconium exclusively during intrauterine life and are excreted after birth. METHODS Proteomic analysis was used to investigate the protein composition in pooled 50 serial meconium portions from 10 neonates. The UniProt, BRENDA and MEROPS databases were the sources of information used to classify the meconium proteases and antiproteases among 946 proteins identified in meconium. RESULTS A total of 265 enzymatic proteins and 33 protein inhibitors were identified in the meconium. The six main enzyme groups represented in the meconium were oxidoreductases (n = 44), transferases (n = 62), hydrolases (n = 137), lyases (n = 10), isomerases (n = 7) and ligases (n = 5). Six protease families were distinguished: serine (n = 28, 41.2% of all proteases), metallo (n = 23, 33.8%), cysteine (n = 10, 14.7%), aspartic (n = 4, 5.9%), theorine (n = 2, 2.9%) and mixed (n = 1, 1.5%) proteases. CONCLUSIONS The well-characterized meconium-based biomarker panel of proteases and their inhibitors may be a source of important information for use in diagnosing fetal disorders and predicting postnatal health and development. The differences in the composition and function between individual meconium proteases and antiproteases confirm their association with numerous metabolic processes characteristic of the intrauterine environment.