Plasma gamma-glutamylglycine predicts the seroconversion of hepatitis B e antigen in patients with chronic hepatitis...

The seroconversion of hepatitis B e antigen (HBeAg) remains difficult to be completely obtained in the treatment of hepatitis B. This study aimed to characterize the metabolic signatures of HBeAg-positive patients and identify key metabolites associated with HBeAg seroconversion.

Untargeted metabolomic analysis was conducted to investigate the plasma metabolic profiles of HBeAg-positive (n=54) and negative (n=33) patients. Subgroup analyses were performed in patients with persistent HBeAg<20IU/ml level (n=33) versus those with HBeAg-negative (n=33) and patients with immune tolerant (n=8) versus immune active phases (n=7). Targeted metabolomic analysis was used to validate specific amino acids in an external cohort (n=90). The biological effects of gamma-glutamylglycine were examined by in vitro experiments.

Compared with patients who achieved HBeAg seroconversion, HBeAg-positive patients exhibited distinct metabolic profiles, with 227 differential metabolites (133 downregulated and 94 upregulated, P<0.05). KEGG pathway enrichment analysis revealed downregulated tryptophan, pyruvate, glycine, serine, and threonine metabolism, and glycerophospholipid metabolism and upregulated arginine biosynthesis, and cysteine and methionine metabolism in HBeAg-positive patients (P<0.01). Gamma-glutamylglycine and Na-L-glutamyl-aspartic acid were significantly upregulated in HBeAg-positive patients by both untargeted and targeted metabolomic analysis (P<0.05). Furthermore, a predictive model integrating plasma gamma-glutamylglycine accurately identified HBeAg seroconversion in both developing (AUC = 0.857, 95% CI: 0.765-0.923) and external (AUC = 0.780, 95% CI: 0.680-0.861) cohorts. In vitro assays showed that gamma-glutamylglycine contributed to the production of HBeAg in HBV-replicating cells.

Altered amino acid metabolism is a predominant metabolic feature of HBeAg-positive patients and plasma levels of gamma-glutamylglycine are negatively associated with HBeAg seroconversion.