An exploratory study on the metagenomic and proteomic characterization of hypothyroidism in the first half of pregnancy and correlation with Th1/Th2 balance.

Objective: To explore the gut microbiota and proteomic characteristics of hypothyroidism in the first half of pregnancy (referred to as hypothyroidism in the first half of pregnancy) and its association with Th (T helper cells, Th)1/Th2 balance using metagenomics combined with proteomics.

Methods: Stool and blood samples were collected from 20 hypothyroid (hypothyroidism group) and normal pregnant women (normal group) in the first half of pregnancy. Flora and proteomic characteristics were analyzed using metagenomics sequencing and 4D-DIA proteomics. Th1 and Th2 cells were quantified, and cytokine levels were measured using cellular micro-bead arra. The enzyme-linked immunosorbent test (ELISA) was utilized to assess differential proteins.

Results: (1) Metagenomic sequencing revealed distinct microbial profiles: The β-diversity of gut microbiota was diminished in the hypothyroidism group (p < 0.05). LEfSe analysis identified Phocaeicola vulgatus and Bacteroides fragilis enriched in the hypothyroidism group (p<0.05), and Kyoto Encyclopedia of Genes and Genomes(KEGG) analysis showed significant enrichment in pathways related to peptidoglycan biosynthesis and glycerol ester metabolism.(2) Proteomic analysis demonstrated downregulation of Diacylglycerol Kinase Kappa (DGKK) and P05109|S10A8(S10A8) proteins in the hypothyroidism group, with marked enrichment in the KEGG pathways for vascular smooth muscle contraction and phosphatidylinositol signaling. (3) ELISA validation confirmed that the proteins DGKK and S10A8 were downregulated in pregnant women in the hypothyroidism group.

Conclusion: Increased P. vulgatus and B. fragilis, decreased DGKK and S10A8 proteins, and a left shift in the Th1/Th2 balance in patients with hypothyroidism in the first half of pregnancy may be associated with the development of the disease.