Serum indoxyl sulphate and its relation to albumin and α1-acid glycoprotein as a potential biomarkers of maternal intestinal metabolism during pregnancy and postpartum.

Maria Karlińska,Hanna Zborowska,Ewa Tomaszewska,Radosław Jaźwiec,Barbara Lisowska-Myjak,Ewa Skarżyńska

doi:10.1371/journal.pone.0259501

Abstract

BackgroundSerum indoxyl sulfate (IS) levels depend on the production of indole in the gut. The biological effects of IS in the vascular bed could be confirmed by changes in the levels of individual serum proteins during normal pregnancy and in the postpartum period as compared with non-pregnant controls. Albumin (Alb) and α1-acid glycoprotein (AGP, orosomucoid) are the most abundant serum carrier proteins with potential interrelationships with serum levels of IS.MethodsSerum levels of IS, Alb and AGP were measured in 84 pregnant women in the first, second and third trimester of pregnancy and in the postpartum period, as well as in non-pregnant controls (n = 20), using ultra-performance liquid chromatography (UPLC) coupled to mass spectrometry (IS), colorimetric assay (Alb) and immunoturbidimetric assay (AGP).ResultsThe postpartum serum levels [mg/L] of IS were lower (p = 0.027) than in the second trimester (mean±SD: 0.85±0.39 vs 0.58±0.32). There were no differences in the IS to ALB ratio calculated in the three trimesters of pregnancy, the postpartum period, and in the non-pregnant controls. The IS/AGP ratio increased from the first to the second trimester (p = 0.039), and decreased in the postpartum period (p<0.05), when it was lower than in the second and third trimester.ConclusionsThe variability of the serum IS/AGP ratio during pregnancy and in the postpartum period may reflect shared involvement in the regulation of their intravascular relationships. The link between serum levels of IS derived from the gut and AGP could serve a potential biomarkers of maternal intestinal metabolism during pregnancy and postpartum.

Highlights

Gut-specific serum markers measured in pregnancy and the postpartum period may be a source of information about the biological role of the gut in maintaining homeostasis of the materno-fetal complex.Indoxyl sulfate (IS) is a small-molecular-weight endogenous metabolite (213 Da) of dietary L-tryptophan and its synthesis and serum levels depend on gut, liver and kidney function [1,2,3,4,5,6]
Serum levels of IS, Alb and AGP were measured in 84 pregnant women in the first, second and third trimester of pregnancy and in the postpartum period, as well as in non-pregnant controls (n = 20), using ultra-performance liquid chromatography (UPLC) coupled to mass spectrometry (IS), colorimetric assay (Alb) and immunoturbidimetric assay (AGP)
There were no differences in the IS to ALB ratio calculated in the three trimesters of pregnancy, the postpartum period, and in the non-pregnant controls

Summary

Introduction

Indoxyl sulfate (IS) is a small-molecular-weight endogenous metabolite (213 Da) of dietary L-tryptophan and its synthesis and serum levels depend on gut, liver and kidney function [1,2,3,4,5,6]. Albumin (Alb) and α1-acid glycoprotein (AGP, orosomucoid), produced in the liver, are the most important serum carrier proteins that play a role in transporting endogenous and exogenous ligands [13, 14]. The biological effects of IS in the vascular bed could be confirmed by changes in the levels of individual serum proteins during normal pregnancy and in the postpartum period as compared with non-pregnant controls. Albumin (Alb) and α1-acid glycoprotein (AGP, orosomucoid) are the most abundant serum carrier proteins with potential interrelationships with serum levels of IS.

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