Multiple studies have confirmed dysbiosis in ankylosing spondylitis (AS) and inflammatory bowel disease (IBD); however, due to methodological differences across studies, it has not been possible to determine if these diseases have similar or different gut microbiomes. In this study, faecal and intestinal biopsies were obtained from 33 Australian AS patients (including 5 with concomitant IBD, ‘AS-IBD’), 59 IBD patients and 105 healthy controls. Stool samples were also obtained from 16 Italian AS patients and 136 Swedish AS patients. Focusing on the Australian cohort, AS, AS-IBD and IBD patients differed from one another and from healthy controls in both alpha and beta diversity. AS patients with and without clinical IBD could be distinguished from one another with moderate accuracy using stool microbiome (AUC=0.754). Stool microbiome also accurately distinguished IBD patients from healthy controls (AUC=0.757). Microbiome composition was correlated with disease activity measured by BASDAI and faecal calprotectin (FCP) levels. Enrichment of potentially pathogenic Streptococcus was noted in AS, AS-IBD and IBD patients. Furthermore, enrichment of another potentially pathogenic genus, Haemophilus, was observed in AS, AS-IBD, IBD, AS patients with increased BASDAI, and IBD patients with faecal calprotectin >100 μg/mg. Apart from these genera, no other taxa were shared between AS and IBD patients. In conclusion, the distinct gut microbiome of AS and AS-IBD patients compared to IBD patients and healthy controls is consistent with immunological and genetic evidence suggesting that the gut plays a different role in driving AS compared with IBD. However, enrichment of two potentially pathogenic genera in both diseases suggests that the presence of a shared/common microbial trigger of disease cannot be discounted.

中文翻译：

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强直性脊柱炎和炎症性肠病患者独特的肠道微生物组表明其在发病机制中的不同作用并与疾病活动相关

多项研究证实了强直性脊柱炎 (AS) 和炎症性肠病 (IBD) 的生态失调；然而，由于研究之间的方法学差异，无法确定这些疾病是否具有相似或不同的肠道微生物组。在这项研究中，来自 33 名澳大利亚 AS 患者（包括 5 名伴有 IBD，“AS-IBD”）、59 名 IBD 患者和 105 名健康对照者的粪便和肠道活检。粪便样本也来自 16 名意大利 AS 患者和 136 名瑞典 AS 患者。关注澳大利亚队列，AS、AS-IBD 和 IBD 患者在 α 和 β 多样性方面彼此不同，并且与健康对照组不同。使用粪便微生物组（AUC=0.754）可以以中等准确度区分患有和不患有临床 IBD 的 AS 患者。粪便微生物组还可以准确地区分 IBD 患者和健康对照组（AUC=0.757）。微生物组组成与通过 BASDAI 和粪便钙卫蛋白 (FCP) 水平测量的疾病活动相关。在 AS、AS-IBD 和 IBD 患者中发现了潜在致病性链球菌的富集。此外，在 AS、AS-IBD、IBD、BASDAI 增加的 AS 患者和粪便钙卫蛋白 >100 μg/mg 的 IBD 患者中观察到另一种潜在致病菌属嗜血杆菌的富集。除了这些属之外，AS 和 IBD 患者之间没有共享其他分类群。总之，与 IBD 患者和健康对照相比，AS 和 AS-IBD 患者的不同肠道微生物组与免疫学和遗传证据一致，表明与 IBD 相比，肠道在驱动 AS 中发挥不同的作用。然而，