P501 - NEUTROPHILS AS A CRITICAL MEDIATOR IN THE RELATIONSHIP BETWEEN 25-HYDROXYVITAMIN D AND LUNG FUNCTION IN PARTICIPANTS WITH INFLAMMATORY BOWEL DISEASE FROM THE UK BIOBANK

P501

NEUTROPHILS AS A CRITICAL MEDIATOR IN THE RELATIONSHIP BETWEEN 25-HYDROXYVITAMIN D AND LUNG FUNCTION IN PARTICIPANTS WITH INFLAMMATORY BOWEL DISEASE FROM THE UK BIOBANK

Y.-P. Hao^1,*, C.-J. Lai², H.-Y. Fan¹, C. L. Yeh¹

¹School of Nutrition and Health Sciences, Taipei Medical University, ²Department of Anesthesiology, National Taiwan University Hospital, Taipei, Taiwan, Province of China

Rationale: The typical range of serum 25-hydroxyvitamin D (25-OHD) was associated with lower inflammatory markers and better lung function. However, the relationship between these factors in inflammatory bowel disease (IBD) patients remains unclear. This study aimed to identify the inflammatory markers that correlate with serum 25-OHD levels and lung function in IBD patients.

Methods: Participants were from the UK Biobank; 4088 participants with IBD were selected. After excluding unqualified participants, a total of 4,028 participants were included. Serum 25-OHD levels were measured and categorized into quintiles as follows: Q1 (10–28 ng/mL), Q2 (28–40 ng/mL), Q3 (40–51 ng/mL), Q4 (51–65 ng/mL), and Q5 (65–100 ng/mL). Q1 was used as the reference group. Linear regression was performed to assess differences in inflammatory-biomarkers and lung function parameters between Q1 and Q2–Q5. Additionally, counterfactual analysis was conducted to identify which inflammatory-biomarkers mediated the relationship between serum 25-OHD levels and lung function in participants with IBD.

Results: Participants in Q2 to Q5 showed better lung function and lower inflammatory markers than those in Q1, especially in Q3. A one standard deviation increase in serum 25-OHD concentration was associated with a reduction in neutrophil counts (β = -80.4 × 10⁹ cells/mL, p = 0.012) and mediated the relationship between serum 25-OHD and lung function (10% mediation proportion, p = 0.01). This increase in serum 25-OHD associated with a 30 mL rise in both FEV1 and FVC.

Conclusion: Neutrophil count may serve as a crucial biomarker linking serum 25-OHD levels to lung function in individuals with IBD.

Disclosure of Interest: None declared