AB0155 INTESTINAL MICROBIAL SIGNATURE IN ANKYLOSING SPONDYLITIS

Abstract

Background: Intestinal microbiota analysis is a current subject because of its important role in the pathogenesis of various autoimmune diseases such as intestinal inflammatory diseases or spondyloarthritis. Objectives: The objective of this paper was to perform a quantitative determination of the intestinal microbiota in patients with ankylosing spondylitis (AS) and to highlight the main characteristics of intestinal dysbiosis in these cases. Methods: We conducted a case-control prospective study that included 28 patients with AS and 32 control cases (healthy individuals). Intestinal microbiota analysis was performed by real-time PCR (polymerase chain reaction) in faeces. Intestinal microbiota analysis focused on the following bacterial species: Bacteroides, Bifidobacterium, Clostridium coccoides (XIVa) (C. Coccoides), Clostridium leptum (IV) (C. Leptum), Faecalibacterium prausnitzii (F. Prausnitzii), Lactobacillus, Escherichia coli (E. coli). Results: Intestinal disbiosis in AS patients was characterized by a significant bacterial decrease compared to the control arm. Some bacterial species showed a numerical growth: Bacteroides, C. coccoides and C. leptum, F. prausnitzii. In other bacterial groups there was a significant decrease: Bifidobacterium, Lactobacillus and E. coli. Statistically significant correlations were observed only for Bifidobacterium, significantly increased in the axial form of AS compared to the peripheral form (p = 0.035). Other bacterial groups were numerically elevated in the axial form of AS (except Bacteroides), without statistically significant differences. In all AS cases, a moderate disease activity was evidenced (mean BASDAI = 4.83, mean BASFI = 9.11). BASDAI score inversely correlated with the total bacteria group (p = 0.010, r = -0.606) - intestinal dysbiosis worsens as disease activity increases. Also, direct proportional correlations were highlighted between BASDAI and F. prausnitzii (p = 0.000, r = 0.764), respectively Lactobacillus (p = 0.047, r = 0.488). An increase in AS activity is associated with an increase in proinflammatory bacteria. BASFI score statistically correlated with the total bacterial count (p = 0.000, r = -0.764), F. prausnitzii (p = 0.010, r = 0.606), Bifidobacterium (p = 0.016, r = 0.843) and E. coli (p = 0.016, r = 0.575). An important decrease in the functionality of these patients correlates with a decrease in total bacterial diversity. Improvement of intestinal dysbiosis has been observed in patients on synthetic and biological immunosuppressive therapy compared to the control arm. Conclusion: The study highlightes the characteristics of intestinal dysbiosis in AS patients. There is a direct relationship between the composition of intestinal microbiota and the AS activity scores. Specific treatment for AS leads to a decrease in proinflammatory bacteria, improving gut dysbiosis.