P458 The microbiota in Crohn's disease and health is it the same in the East and West? The effects of geography, ethnicity and disease on microbiota

Abstract

Background: Crohn's disease (CD) mucosa-associated microbiota (MAM) differs from health and drives the inflammatory process. With CD increasing rapidly in the East, including Hong Kong (HK), understanding the nature of the MAM in an established and disease-emerging population, both in health and disease, offers the possibility of discovering key aetiological microbial factors. Methods: Mucosal biopsies were taken from the ileum of 7 Australian CD Caucasians undergoing resection (A-CDC-res). Colonoscopic ileal biopsies were taken from: 6 Australian healthy Caucasians (A-HC), 7 Australian CD Caucasians 6 months after surgery (A-CDC-6m), 6 Australian healthy Asians (A-HA), 6 HK healthy Asians (HK-HA), and 5 HK CD Asians (HK-CDA). Pyrosequencing characterised the bacterial 16s rRNA regions V1-V2. Amplicons were analysed using MOTHUR, providing more than 500,000 high-quality chimera-free reads. Results: Geography alone did not affect MAM diversity, with no difference (OTU number 97% similarity and Inverse Simpson Diversity Measurement (SDM)) between Australian healthy Caucasian, Australian healthy Asian or HK healthy subjects (figures 1, 2). Healthy versus CD: CD was associated with altered MAM. Bacterial diversity (OTU number per sample and SDM) was significantly lower for CD patients compared to healthy subjects in both Australia and HK. CD in East versus West: CD MAM may differ geographically. HK CD patients tended to have a lower OTU number than Australian Caucasian CD patients (ACDC) (p = 0.058) (figures 1, 2). (Figure presented) Conclusions: This is the first study examining the contribution of geography, ethnicity and disease on MAM. Disease, but not healthy, MAM differs geographically. These data provide potential central insights into causes of CD, geographical differences in disease, and the causes of CD emergence in the East.