The autophagy reaction in the human umbilical cord: a potential marker for estimating fetal nutrition and neonatal growth

Objective: To assess the induction of autophagy in the human umbilical cord for physiological adaptation against starvation. Methods: The expression of autophagy-related proteins (LC3-II, p62) in umbilical cord tissues from 40 neonates was assessed by Western blotting. The correlation between the expression of autophagy-related proteins and maternal findings (height, weight, body mass index [BMI]), placental weight, neonatal findings (gestational age, height, weight, Apgar score at 1 min and 5 min), and the pH of the umbilical arterial blood were analyzed using Spearman's rank correlation coefficient test (p values of <.05 were considered significant). Venous blood findings (pH, pCO(2), glucose, total protein, albumin, and lactic acid) were also evaluated in 16 neonates admitted to the NICU. Results: The expression of LC3-II was positively correlated with serum total protein (rho = 0.564, p = .023). The p62 level was also correlated with maternal BMI (rho = 0.376, p = .017), the neonatal Apgar score at 1 min (rho = 0.331 p = .037), total protein (rho = 0.588, p = .017), and albumin (rho = 0.552, p = .027) positively. A multiple linear regression analysis that included clinical parameters related to fetal nutrition and neonatal growth revealed that serum total protein was significantly associated with both LC3-II (p = .024) and p62 (p = .034) in the umbilical cord. Conclusion: The LC3-II or p62 expression in the umbilical cord may suggest the autophagy reaction for the homeostasis of protein or amino acid metabolism in the perinatal period.