A multidimensional blood stimulation assay reveals immune alterations underlying systemic juvenile idiopathic arthritis [RNA-Seq]

Despite great scientific and technological advances, immune alterations predisposing to sporadic human inflammatory diseases remain mostly unknown. To fill this gap, we developed a strategy to evaluate blood leukocyte responses to innate stimuli, simultaneously at the transcriptional, cellular and secreted protein levels. The data were integrated using weighted gene co-expression network analysis. When applied to systemic juvenile idiopathic arthritis (sJIA), an autoinflammatory disease of unknown etiology, this approach identified gene sets associated with specific cytokine environments and activated leukocyte subsets. During the remission phase of disease and off treatment, sJIA patients displayed dysregulated responses to TLR4, TLR8 and TLR7 stimulation in blood. Isolated sJIA monocytes accumulated higher levels of intracellular IL-1ß after stimulation, and underexpressed the IL-1 inhibitor AHR at baseline. In line with the recent demonstration that AHR downregulation in monocytes is linked to macrophage differentiation, we show that the differentiation of sJIA monocytes in vitro was skewed towards macrophages, away from dendritic cell phenotype. This might contribute to the increased incidence of macrophage activation syndrome in these patients. The integrated analysis of these high-dimensional data can thus help unravel underlying immune alterations predisposing to complex inflammatory diseases. Overall design: 32 total samples, 4 control healthy in vitro, 6 control systemic JIA in vitro, 4 LPS healthy in vitro, 6 LPS systemic JIA in vitro, 5 healthy ex vivo, 7 systemic JIA ex vivo