Possible mechanisms of neutrophil activation in Behçet's disease

• BD is probably an immune-mediated inflammatory disorder with PMN hyperactivity.
• IL-17 axis may have important role in BD pathogenesis.
• Natural killer and gamma–delta T cells are natural candidates for IL-17 sources in BD.
• Bacterial triggers for BD may act on monocytes and endothelial cells by TLR.
• Type-I interferon may be a regulator of PMN activity in BD.

Behçet's disease (BD) is a systemic inflammatory disorder characterized by recurrent episodes of acute inflammation consisting mainly of neutrophil infiltration around blood vessels in affected tissues. BD probably occurs due to neutrophil-based innate immune responses orchestrated by a complex interplay among gamma–delta T lymphocytes, natural killer T cells, monocytes and Th17 lymphocytes in which type-I interferon is possibly a key element for inflammatory downregulation. However, strong evidence is still scarce. This article compiles the literature in an attempt to summarize the possible mechanisms by which neutrophils are activated in BD and suggests directions for future research.

An overview about possible mechanisms of polymorphonuclear (PMN) neutrophil activity regulation in Behçet's disease (BD). All mechanisms are hypotheses based mostly on basic experimental evidence and need further research for confirmation. New inferences are the weakest points and are marked with “?”. PAMPS, pathogen associated molecular patterns; LTA, lipoteichoic acid; TLR, toll-like receptor; IFN, interferon; IL, interleukin.Figure optionsDownload as PowerPoint slide