Abstract
IntroductionPrior studies have established altered microbiota and immunologic reactivity to enteric commensal organisms in inflammatory bowel disease (IBD). Since intestinal inflammation is present in a subset of patients with both pediatric and adult spondyloarthritis (SpA), we hypothesized that SpA patients may also have altered microbiota and immune responsiveness to enteric organisms.MethodsStool and blood specimens were collected from children with enthesitis-related arthritis (ERA) and non-inflammatory controls. DNA purified from stool was subject to PCR amplification and sequencing of the variable IV region from the 16S rDNA gene. IgA and IgG Enzyme-linked Immunosorbent Assays (ELISAs) were performed on select species of bacteria in most subjects.ResultsTwenty-five children with ERA and 13 controls were included. The ERA patients had less Faecalibacterium prausnitzii (3.8% versus 10%, P = 0.008) and lachnospiraceae family (12 versus 7.0%, P = 0.020), a statistically significant increase in bifidobacterium (1.8% versus 0%, P = 0.032) and a non-statistically significant increase in Bacteroides (21% versus 11%, P = 0.150). Akkermansia muciniphila was abundant (>2%) in 7/27 ERA patients but none of the controls (P = 0.072.) Cluster analysis revealed two clusters of ERA patients: Cluster one (n = 8) was characterized by high levels of Bacteroides genus, while a second (n = 15) cluster had similar levels as the controls. Seven of 17 (41%) of the ERA subjects in Cluster 2 compared to 0/8 of the subjects in Cluster 1 had abundant Akkermansia muciniphila (P = 0.057). Serum IgA and IgG antibody levels against F. prausnitzii and B. fragilis were similar between patients and controls, whereas the two groups showed divergent responses when the fecal relative abundances of F. prausnitzii and Bacteroides were compared individually against IgA antibody levels recognizing F. prausnitzii and B. fragilis, respectively.ConclusionThe abundance of F. prausnitzii in the stool among patients with ERA is reduced compared to controls, and Bacteroides and A. muciniphila are identified as associative agents in subsets of ERA patients. Differences in the humoral responses to these bacteria may contribute to disease.Electronic supplementary materialThe online version of this article (doi:10.1186/s13075-014-0486-0) contains supplementary material, which is available to authorized users.
Highlights
Prior studies have established altered microbiota and immunologic reactivity to enteric commensal organisms in inflammatory bowel disease (IBD)
Analysis at the species level revealed that 84% of the Faecalibacterium sequences represented a single species: Faecalibacterium prausnitzii, which constituted 10% of the microbiota of control patients versus 3.8% in the enthesitis-related arthritis (ERA) group (P = 0.008.) A basic local alignment search tool (BLAST) search of the operational taxonomic unit (OTU) representing the majority of the unspecified Lachnospiraceae family members revealed two matches at 100% identified: Fusicatenibacter saccharivorans and Clostridium clostridioforme
There were no significant associations between the body mass index of the subjects and presence of any of these bacteria (Additional file 1: Table S1.) Among subjects with ERA, HLA-B27 status was not associated with significant differences in the levels of these bacteria (Additional file 1: Table S2)
Summary
Prior studies have established altered microbiota and immunologic reactivity to enteric commensal organisms in inflammatory bowel disease (IBD). Since intestinal inflammation is present in a subset of patients with both pediatric and adult spondyloarthritis (SpA), we hypothesized that SpA patients may have altered microbiota and immune responsiveness to enteric organisms. Recent genetic advances have shed some light on pathogenesis and have shown important overlap with inflammatory bowel disease (IBD) [2,3]; there still remain important environmental. Studies have shown altered microbiota in a variety of inflammatory conditions, including IBD, rheumatoid arthritis (RA), type I diabetes, and celiac disease [7]. As this study did not use generation sequencing technology, the nature of the microbiota in SpA patients has yet to be fully assessed
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