Dysregulation of proinflammatory versus anti-inflammatory human T_H17 cell functionalities in the autoinflammatory Schnitzler syndrome.

Abstract

T_H17 cells have so far been considered to be crucial mediators of autoimmune inflammation. Two distinct types of T_H17 cells have been described recently, which differed in their polarization requirement for IL-1β and in their cytokine repertoire. Whether these distinct T_H17 phenotypes translate into distinct T_H17 cell functions with implications for human health or disease has not been addressed yet. We hypothesized the existence of proinflammatory and anti-inflammatory human T_H17 cell functions based on the differential expression of IL-10, which is regulated by IL-1β. Considering the crucial role of IL-1β in the pathogenesis of autoinflammatory syndromes, we hypothesized that IL-1β mediates the loss of anti-inflammatory T_H17 cell functionalities in patients with Schnitzler syndrome, an autoinflammatory disease. To assess proinflammatory versus anti-inflammatory T_H17 cell functions, we performed suppression assays and tested the effects of IL-1β dependent and independent T_H17 subsets on modulating proinflammatory cytokine secretion by monocytes. Patients with Schnitzler syndrome were analyzed for changes in T_H17 cell functions before and during therapy with IL-1β-blocking drugs. Both T_H17 cell subsets differ in their ability to suppress T-cell proliferation and their ability to modulate proinflammatory cytokine production by antigen-presenting cells because of their differential IL-10 expression properties. In patients with Schnitzler syndrome, systemic overproduction of IL-1β translates into a profound loss of anti-inflammatory T_H17 cell functionalities, which can be reversed by anti-IL-1β treatment. IL-1β signaling determines the differential expression pattern of IL-10, which is necessary and sufficient to induce proinflammatory versus anti-inflammatory T_H17 cell functions. Our data introduce T_H17 cell subsets as novel players in autoinflammation and thus novel therapeutic targets in autoinflammatory syndromes including other IL-1β mediated diseases. This demonstrates for the first time alterations in the adaptive immune system in patients with autoinflammatory syndromes.