Human β-Defensin 2 in Primary Sclerosing Cholangitis

Area of Science:

• Immunology
• Gastroenterology
• Hepatology

Background:

• Primary sclerosing cholangitis (PSC) is a chronic bile duct inflammatory disease often linked to inflammatory bowel disease (IBD).
• The gut-liver axis plays a crucial role in PSC pathogenesis.
• Defensins, like human beta-defensin 2 (HBD2), are antimicrobial peptides vital for innate immunity at mucosal surfaces and implicated in IBD.

Purpose of the Study:

• To investigate the gene copy number variation of DEFB4, which encodes HBD2.
• To assess the protein expression of HBD2 in patients with PSC.
• To explore the role of HBD2 in the etiopathogenesis of PSC.

Main Methods:

• Quantitative real-time PCR and paralog ratio test were used to determine HBD2 gene copy number in US and Italian PSC patients and controls.
• Serum HBD2 levels were quantified using enzyme-linked immunosorbent assay.
• Liver tissue expression of HBD2 was analyzed via immunohistochemistry.

Main Results:

• Mean serum HBD2 levels were significantly elevated in PSC patients compared to those with primary biliary cholangitis, ulcerative colitis, and healthy controls (P=0.02).
• No significant differences in high DEFB4 gene copy number frequencies (>4 copies) were found between PSC patients and controls across cohorts.
• Immunohistochemistry revealed a higher prevalence of HBD2-positive biliary ducts in PSC samples compared to controls.

Conclusions:

• Elevated serum levels and tissue expression of HBD2 are evident in individuals with PSC.
• These findings highlight the potential involvement of HBD2 within the innate immune system in the development of PSC.
• HBD2 may represent a significant factor in the gut-liver axis's role in PSC etiopathogenesis.