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Objective To determine whether disease processes related to granulomatosis with polyangiitis (Wegener's) (GPA) are reflected in gene expression profiles of the nasal mucosa. Methods Nasal brushings of the inferior turbinate were obtained from 32 patients with GPA (10 with active nasal disease, 13 with prior nasal disease, and 9 with no history of nasal disease) and a composite comparator group with and without inflammatory nasal disease (12 healthy people, 15 with sarcoidosis, and 8 with allergic rhinitis). Differential gene expression was assessed between subgroups of GPA and comparators. Results A total of 339 genes were differentially expressed between the GPA and comparator groups (absolute fold change >1.5; false discovery rate <0.05). Top canonical pathways up-regulated in nasal brushings from patients with GPA included granulocyte adhesion and diapedesis ( P = 8.6−22), agranulocyte adhesion and diapedesis ( P = 1.3−14), IL10 signaling ( P = 3.0−11), LXR/RXR activation ( P = 4.3−11), and TREM1 signaling ( P = 9.0−11). A set of genes differentially expressed in GPA independently of nasal disease activity status included genes related to epithelial barrier integrity (fibronectin 1, desmosomal proteins) and several matricellular proteins (e.g., osteonectin, osteopontin). Significant overlap of differentially expressed genes was observed between active and prior nasal disease GPA subgroups. Peripheral blood neutrophil and mononuclear gene expression levels associated with GPA were similarly altered in the nasal gene expression profiles of patients with active or prior nasal disease. Conclusion Profiling the nasal transcriptome in GPA reveals gene expression signatures related to innate immunity, inflammatory cell chemotaxis, extracellular matrix composition, and epithelial barrier integrity. Thus, airway-based expression profiling is feasible and informative in GPA. [ABSTRACT FROM AUTHOR]

Objective To discover biomarkers involved in the pathophysiology of antineutrophil cytoplasmic antibody-associated vasculitis (AAV) and to determine whether low-density granulocytes (LDGs) contribute to gene expression signatures in AAV. Methods The source of clinical data and linked biologic specimens was a randomized controlled treatment trial in AAV. RNA sequencing of whole blood from patients with AAV was performed during active disease at the baseline visit and during remission 6 months later. Gene expression was compared between patients who met versus those who did not meet the primary trial outcome of clinical remission at 6 months (responders versus nonresponders). Measurement of neutrophil-related gene expression was confirmed in peripheral blood mononuclear cells (PBMCs) to validate the findings in whole blood. A negative-selection strategy isolated LDGs from PBMC fractions. Results Differential expression between responders (n = 77) and nonresponders (n = 35) was detected in 2,346 transcripts at the baseline visit ( P < 0.05). Unsupervised hierarchical clustering demonstrated a cluster of granulocyte-related genes, including myeloperoxidase (MPO) and proteinase 3 (PR3). A granulocyte multigene composite score was significantly higher in nonresponders than in responders ( P < 0.01) and during active disease than during remission ( P < 0.01). This signature strongly overlapped an LDG signature identified previously in lupus (false discovery rate by gene set enrichment analysis <0.01). Transcription of PR3 measured in PBMCs was associated with active disease and treatment response ( P < 0.01). LDGs isolated from patients with AAV spontaneously formed neutrophil extracellular traps containing PR3 and MPO. Conclusion In AAV, increased expression of a granulocyte gene signature is associated with disease activity and decreased response to treatment. The source of this signature is likely LDGs, a potentially pathogenic cell type in AAV. [ABSTRACT FROM AUTHOR]