The Intestinal Microbiome in Spondyloarthritis

Tejpal Gill; Mark Asquith; James T. Rosenbaum; Robert A. Colbert


Curr Opin Rheumatol. 2015;27(4):319-325. 

In This Article

The Gut Microbiota

The gut microbiota is the vast microbial community that inhabits our intestine. Microbial cells outnumber host cells by a factor of 10, and collectively harbor 100-fold more genes than the human genome.[5] Staggeringly, an estimated 10% of all the metabolites in humans are thought to have microbial origins.[6] This mutually beneficial relationship offers host nutrients to intestinal commensal bacteria, in return for metabolic and physiological capabilities. Cohabitation with microbes seems to be an ever-evolving process with host microbe crosstalk normally involving regulation of immune activation and inflammation.[7] Although the microbiome varies between individuals, familial, and functional similarities are found in the bacterial species represented.[8] Gut microbiome analysis in healthy human populations revealed around 1150 species of bacteria, the majority of which (50–75%) are represented by Firmicutes, followed by Bacteroidetes (10–50%), and Actinobacteria (1–10%), with less than 1% being Proteobacteria.[9] Environmental factors and host genome have both been implicated as contributing to this similarity. The advent of high throughput genome sequencing techniques such as next-generation 16S rRNA sequencing has led to crucial insights into the intestinal metagenome, as more than 70% of the bacterial population including many anaerobes cannot be readily cultured.[9] The ability to routinely obtain an unbiased assessment of gut microbiota has resulted in a more comprehensive view of the gut dysbiosis in SpA patients as well as HLA-B27-driven disease in an animal model. Table 1 [10–16,17,18–22] refers to studies implicating gut bacteria in human diseases and animal models of spondyloarthropathies.