Citrullinated histone H3 expression in anti-neutrophil cytoplasmic antibody-associated vasculitis in older Japanese autopsy patients

Aim Neutrophil extracellular traps play key roles in the necrotizing vasculitis associated with anti-neutrophil cytoplasmic antibody-associated vasculitis (AAV). However, the relationships between neutrophil extracellular traps formation and the distribution and phase of vasculitis are not well understood. In the present study, we clarified the clinicopathological characteristics of older AAV patients, as well as the expression of citrullinated histone H3 (citH3), a marker of neutrophil extracellular traps, in autopsied AAV patients. Methods We reviewed autopsy cases that were carried out at Tokyo Metropolitan Geriatric Hospital, Tokyo, Japan, from 2001 to 2018. The expression of citH3 was determined by immunostaining. Results AAV patients (six cases) were elderly (aged 73-94 years; three men and three women; myeloperoxidase anti-neutrophil cytoplasmic antibody-positive, five cases; proteinase-3 anti-neutrophil cytoplasmic antibody-positive, one case; disease duration was 1.5-5.5 months; and patients were treated with steroids. All patients had necrotizing vasculitis in the medium-to-small-sized vessels in various organs, and also severe vasculitis-associated lesions including brain hemorrhage, alveolar bleeding, interstitial pneumonia, crescentic nephritis, acute pancreatitis and gastrointestinal bleeding. Expression of citH3 was associated with the activity of inflammation. Conclusions We report severe clinicopathological characteristics of AAV in older patients. Expression of citH3 was a useful marker to evaluate vasculitis severity. Identification of these features might aid in the diagnosis of AAV. Geriatr Gerontol Int 2019; 19: 259-264.