Christina Bergqvist, Rémi Safi, George El Hasbani, Ossama Abbas, Abdulghani Kibbi, Dany Nassar
DOI: 10.2340/00015555-3363

Formation of neutrophil extracellular traps has been implicated in autoimmunity. However, the presence and clinical relevance of neutrophil extracellular traps in immune-complex-mediated cutaneous small and medium vessel vasculitides has not been investigated. This study retrospectively analysed 72 patients with histology-proven hypersensitivity vasculitis (n = 21), IgA vasculitis (n = 22), urticarial vasculitis (n = 22), erythema elevatum diutinum (n = 3) and polyarteritis nodosa (n = 4). Neutrophil extracellular traps were detected in hypersensitivity vasculitis, IgA vasculitis, urticarial vasculitis and erythema elevatum diutinum, but not in polyarteritis nodosa lesions. Neutrophil extracellular traps were found around inflamed vessels, and their formation was highest early after the onset of vasculitis and decreased progressively thereafter. Neutrophil extracellular traps were strongly correlated with the histological severity of vasculitis and the production of reactive oxygen species. Both hypersensitivity vasculitis and IgA vasculitis showed significantly more neutrophil extracellular traps than did urticarial vasculitis, independent of the histological severity and duration of vasculitis. These results provide evidence on the implication of neutrophil extracellular traps in the early phases of immune-complex-mediated small vessel vasculitis.

Neutrophils fight microbes by releasing neutrophil extracellular traps, which are DNA tracts studded with antimicrobial peptides. Neutrophil extracellular traps are implicated in autoimmunity. However, their presence and relevance in immune-complex-mediated cutaneous vasculitis is unknown. This study showed that neutrophil extracellular traps are found in the various immune-complex-mediated vasculitides: hypersensitivity vasculitis, IgA vasculitis, urticarial vasculitis, and erythema elevatum diutinum; and their level of production correlates with the severity of vasculitis and the amount of reactive oxygen species produced. Drugs targeting neutrophil extracellular traps are currently under development and might eventually be useful for treatment of difficult-to-treat chronic recurrent small vasculitis, IgA vasculitis relapses, and the notoriously chronic and disfiguring erythema elevatum diutinum.

Figure S1
Table SI