Search

Objective To identify a molecular signature that could be predictive of the clinical response to rituximab (RTX) and elucidate the transcriptomic changes after RTX therapy in patients with rheumatoid arthritis (RA), with the use of whole-blood transcriptomic profiling. Methods A microarray assay of the whole human genome was performed using RNA from peripheral blood samples obtained before the first cycle of RTX from 68 patients with RA in the SMART study. The transcriptomic profile was also assessed 24 weeks after the first administration of RTX (among 24 nonresponders and 44 responders, according to the European League Against Rheumatism response criteria at week 24). Ingenuity Interactive Pathways Analysis was used to identify molecular pathways that were modified by RTX therapy according to the clinical response. Quantitative polymerase chain reaction was performed to confirm the microarray results. Results In total, 198 genes showed significant baseline differential expression between patient groups according to their subsequent response to RTX (good or moderate responder versus nonresponder). This molecular signature could be reduced to 143 genes, which allowed for correctly classifying 89% of the patients by their EULAR response status at week 24, with 93% identification of responders and 100% identification of nonresponders. The signature for response featured up-regulation of inflammatory genes centered on NF-κB, including IL33 and STAT5A, and down-regulation of the interferon pathway. As expected, at week 24 post–RTX therapy, genes involved in the development and functions of B cells were the genes most strongly down-regulated, without any difference between the 2 groups. Conclusion Whole-blood transcriptomic analyses may accurately identify patients with RA who will not respond to RTX therapy. These findings could open new perspectives on the clinical management of RA.

Objective In HLA–B27–transgenic rats, the development of a disorder that mimics spondyloarthritis (SpA) is highly correlated with dendritic cell (DC) dysfunction. The present study was undertaken to analyze the underlying mechanisms of this via transcriptome analysis. Methods Transcriptome analysis of ex vivo–purified splenic CD103+CD4+ DCs from B27-transgenic rats and control rats was performed. Transcriptional changes in selected genes were confirmed by quantitative reverse transcriptase–polymerase chain reaction. A meta-analysis of our rat data and published data on gene expression in macrophages from ankylosing spondylitis (AS) patients was further performed. Results Interferon (IFN) signaling was the most significantly affected pathway in DCs from B27-transgenic rats; the majority of genes connected to IFN were underexpressed in B27-transgenic rats as compared to controls. This pattern was already present at disease onset, persisted over time, and was conserved in 2 disease-prone B27-transgenic rat lines. In DCs from B27-transgenic rats, we further found an up-regulation of suppressor of cytokine signaling 3 (which may account for reverse IFN signaling) and a down-regulation of interleukin-27 (a cytokine that opposes Th17 differentiation and promotes Treg cells). The meta-analysis of data on conventional DCs from rats and data on monocyte-derived macrophages from humans revealed 7 IFN-regulated genes that were negatively regulated in both human and rat SpA (i.e., IRF1, STAT1, CXCL9, CXCL10, IFIT3, DDX60, and EPSTI1). Conclusion Our results suggest that expression of HLA–B27 leads to a defect in IFNγ signaling in antigen-presenting cells in both B27-transgenic rats and SpA patients, which may result in Th17 expansion and Treg cell alteration (as shown in B27-transgenic rats) and contribute to disease pathogenesis.