Tumor Necrosis Factor-alpha Gene Signature Is Absent in Peripheral Blood Mononuclear Cells of Patients with Granulomatosis Polyangiitis

ABSTRACT

OBJECTIVE: Granulomatosis with polyangiitis (GPA), formally known as Wegener's granulomatosis, is a systemic vasculitis with necrotizing granulomatous inflammation. As treatment directed against tumor necrosis factor (TNF)-alpha failed in GPA, we investigated whether "TNF-alpha signature" (i.e. gene expression profile of TNF-alpha activation) was present in peripheral blood mononuclear cells (PBMCs) of patients with GPA. METHODS: Gene expression profiling was performed using total RNA from PBMCs of 41 patients with GPA and 23 healthy control subjects using the Illumina microarray technique. Gene set enrichment analysis (GSEA) was performed to detect the presence of TNF-alpha signature using the curated list C2-V3.0 by the Broad Institute. False discovery rate or =1). In addition, an unsupervised hierarchical clustering of those genes failed to cluster the samples into healthy control subjects and GPA in remission or with active disease. B cell activation signature was enriched in GPA patients. CONCLUSION: Absence of a TNF-alpha signature in PBMCs may suggest that TNF-alpha plays a less important role in the pathogenesis of GPA than previously accepted.