Objective. To identify a gene expression signature in axial spondyloarthritis/ankylosing spondylitis (SpA/AS) and genomic pathways likely to be involved in pathogenesis of SpA/AS patients. Methods. Four publicly accessible microarray studies from SpA/AS patients were integrated, and a transcriptomic and network-based meta-analysis was performed. This meta-analysis was compared with a published microarray study in whole blood of AS patients. Results. According to our meta-analysis, 1,798 genes were differentially expressed in the whole blood of SpA/AS patients compared to healthy controls, while 674 genes were differentially expressed in the synovium of SpA/AS patients compared to healthy controls. When the whole blood meta-analysis data was compared with a published microarray study that also analyzed whole blood in SpA/AS patients, pathways involved in Toll-like receptor signaling, osteoclast differentiation, T cell receptor signaling and janus kinase–signal transducer and activator of transcription (Jak-STAT) signaling were often enriched in SpA/AS. On the other hand, eomesodermin, RUNX3, and interleukin-7 receptor (IL7R) were usually decreased in SpA/AS patients, suggesting that deficiency of these genes contributes to increased IL-17 production in AS. Conclusion. Several common enrichment pathways including Toll-like receptor signaling pathway, osteoclast differentiation, T cell receptor signaling pathway and Jak-STAT signaling pathway were identified in the differentially expressed genes of whole blood and synovium from SpA/AS patients, suggesting that these pathways are involved in the pathogenesis of SpA/AS.

Keywords: Axial spondyloarthritis, Ankylosing spondylitis, Microarray, Network analysis