Dendritic cells play an important role in the initiation of immune reactions. Due to their high capacity to prime T-cell responses, the activation of dendritic cells must be tightly controlled. Because Interleukin-1β (IL-1β) is a key player in autoinflammatory diseases, we compared the ability of IL-1β to activate human dendritic cells and induce immune-regulatory molecules versus the effects induced by pathogen-derived stimuli. Upon activation with either IL-1β or microbial stimuli, monocyte-derived dendritic cells showed enhanced expression of costimulatory molecules, increased secretion of chemokines and cytokines, and the ability to activate T cells. In contrast, immune-feedback molecules, including PD-L1, IL-1RA, IL-10 and SOCS1, were exclusively upregulated in response to microbial stimuli, whereas IL-1β treatment had no inducing effect on them. Thus, the limited capacity of IL-1β to induce potential feedback inhibitors may support its key etiologic role in chronic inflammation and autoinflammatory responses.
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