Question: Write a study description for the study titled 'The bile acid metabolome in umbilical cord blood and meconium of healthy newborns: Distinct characteristics and implications (Meconium analysis)'.
Answer: OBJECTIVE: To characterize the bile acid (BA) metabolomic profile of umbilical cord blood (UCB) and meconium in healthy newborns.METHODS: Fifteen healthy newborns, which born in the Obstetrics Department of the Affiliated Hospital of Southwest Medical University between July 1 and August 31, 2023, were selected as study subjects. UCB and meconium samples were collected, and BA metabolomics were analyzed using ultra-high performance liquid chromatography-tandem mass spectrometry.RESULTS: UCB predominantly contained primary bile acids (PBAs), whereas meconium was rich in secondary bile acids (SBAs). The PBAs/SBAs ratio in UCB was significantly higher than in meconium [2.64 (2.49, 5.70) vs 0.99 (0.37, 1.58), P < 0.001]. Both UCB and meconium were primarily composed of conjugated BAs. However, the ratio of unconjugated to conjugated BAs was notably higher in UCB than in meconium [0.14 (0.07, 0.18) vs 0.01 (0.01, 0.04), P < 0.001]. In terms of individual metabolite, UCB was dominated by taurochenodeoxycholic acid (TCDCA), taurocholic acid (TCA), and glycochenodeoxycholic acid (GCDCA), while meconium was abundant in TCA, taurohyocholic acid, and TCDCA. Conjugated PBAs in UCB primarily originated from chenodeoxycholic acid (CDCA), whereas those in meconium were mainly derived from cholic acid (CA). The CA/CDCA ratio in conjugated PBAs was significantly lower in UCB than in meconium [0.59 (0.19, 0.75) vs 2.21 (1.34, 3.04), P < 0.001]. SBAs in both UCB and meconium were primarily derived from CDCA, but the CA/CDCA ratio was significantly higher in UCB than in meconium [0.42 (0.21, 0.63), vs 0.03 (0.01, 0.05), P < 0.001]. No PBAs in UCB correlated with their counterparts in meconium, and only three PBAs (TCDCA, GCDCA, and glycochenodeoxycholic acid 3-glucoside in UCB) were correlated with their downstream metabolites in meconium [with hyodesoxycholic acid (HDCA) (r = -0.66, P = 0.01), Tauro-ω-muricholic acid (TωMCA) (r = 0.52, P = 0.048) and ursodeoxycholic acid-7S (r = -0.53, P = 0.04), respectively]. In meconium, most of PBAs were correlated with their downstream metabolites (P all < 0.05): CA was positively correlated with 3-dehydrocholic acid (3-DHCA), TCA was positively correlated with TDCA and 3-DHCA, GCA was positively correlated with 3-DHCA, CDCA was positively correlated with GUDCA, taurolithocholic acid (TLCA), and 7-keto Lithocholic acid (7-KetoLCA) and negatively correlated with isolithocholic acid (isoLCA). TCDCA was positively correlated with THDCA, TUDCA, GUDCA, TLCA, TωMCA, and GHDCA, while GCDCA was positively correlated with TUDCA, GUDCA, TLCA, and GHDCA, and negatively correlated with isoLCA.CONCLUSION: The BA metabolites in UCB and meconium differ significantly, and the downstream BA metabolites in meconium are predominantly correlated with their upstream BAs in meconium, but not those BAs in UCB. These findings contribute to a better understanding of BA metabolism in utero and lay the foundation for future research in this topic.Meconium analysis is reported in the current study MTBLS10267.Umbilical cord blood analysis is reported in MTBLS10266.