P169 Copy number variation of alpha defensin 1-3 is a predictive marker of therapeutic response in ulcerative colitis

Abstract

Abstract Background Alpha-defensin 1-3 (DEFA1A3) is an antimicrobial peptide found in phagocytic cells such as neutrophils, functioning as an effector factor in innate immunity. Reports suggest that copy number variation (CNV) of the DEFA1A3 gene is associated with the severity of ulcerative colitis (UC). However, the impact of DEFA1A3 on the pathogenesis of UC, and treatment response has not been fully investigated. Therefore, we aimed to evaluate the relationship between DEFA1A3-CNV and UC treatment response. Methods This was a retrospective and two medical centers study. The study included UC patients with DEFA1A3-CNV measurements, who attended our department and related facilities between 2020 and 2022. Clinical background and white blood cell count and serological marker were collected from the medical records of included patients. DEFA1A3-CNV was measured using droplet digital PCR after DNA extraction from peripheral blood mononuclear cells. Mayo score was used to determine the response to treatment and severity of UC. Results In total, 197 UC patients were included in the study. The median DEFA1A3 copy number was 7.36, and there was a significant correlation between DEFA1A3 copy number and Mayo score. The high DEFA1A3 copy number group had a significantly higher severity of UC during the observation period, compared with the low copy number group. In the analysis of the relationship between prednisolone/immunosuppressive therapy and DEFA1A3-CNV, the DEFA1A3 copy number was significantly higher in the non-remission group than in the remission group following prednisolone treatment. However, there was no correlation between other immunosuppressive therapies and DEFA1A3 copy number. Conclusion DEFA1A3 copy number is a predictive marker of disease severity and prednisolone treatment response.