Characterization of Periplaneta americana glycoproteins' structures and their potential to treat immunological liver fibrosis

In clinical practice, for patients with autoimmune hepatitis (AIH), appropriate therapeutic measures focus on addressing the progression of liver fibrosis (LF) and promptly assessing its severity. This study aims to identify and characterize Periplaneta americana glycoproteins (PAG) and explore their potential mechanisms of action in the treatment of immune liver fibrosis (ILF). PAG was confirmed to be a glycoprotein through Periodic acid-Schiff and Coomassie brilliant blue staining, with protein and total sugar contents of 68.35 0.01% and 17.66 0.22%, respectively. PAG was analyzed using amino acid analysis, monosaccharide analysis, Fourier transform infrared spectroscopy, and ultraviolet spectroscopy. It was found to be composed of 21 amino acids and seven monosaccharides linked via O-glycosidic bonds. In vivo, evaluation of the anti-ILF effects of PAG demonstrated that PAG alleviated Concanavalin A-induced pathological liver damage, restored liver function, alleviated LF, and reduced macrophage infiltration in mice. In addition, PAG regulated the balance between M1/M2 macrophages in the liver and Th1/Th2 cells in the spleen of mice. In the formation of ILF in mice and treatment with PAG, the differentially expressed genes in the mouse liver were mainly enriched in the peroxisome proliferator-activated receptor (Ppar) signaling pathway. This indicates that PAG exerts therapeutic ILF effects by regulating the Ppar signaling pathway. Therefore, this study suggests that PAG has the potential to be developed as a therapeutic drug for improving AIH and provides a new option for the treatment of ILF.