Neutrophil cannibalism triggers transforming growth factor β1 production and self regulation of neutrophil inflammatory function in monosodium urate monohydrate crystal-induced inflammation in mice.

Stefanie Steiger, Jacquie L Harper

Malaghan Institute of Medical Research, Wellington, New Zealand.

Arthritis and rheumatism 2013 Mar

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To identify macrophage-independent sources of transforming growth factor β1 (TGFβ1) production during monosodium urate monohydrate (MSU) crystal-induced inflammation and to determine how TGFβ1 alters MSU crystal-recruited neutrophil functions. C57BL/6J mice were injected intraperitoneally with MSU crystals with or without TGFβ1-neutralizing antibody. MSU crystal-recruited peritoneal and blood neutrophils were purified and cultured ex vivo. Peritoneal neutrophils were treated with the caspase inhibitor Q-VD-OPh, anti-TGFβ1 antibody, or fluorochrome-labeled apoptotic neutrophils. Neutrophils were analyzed for expression of annexin V, caspase 3, and TGFβ1 by flow cytometry or fluorescence microscopy, for superoxide production using the redox-sensitive dye water-soluble tetrazolium 1, and for TGFβ1 and interleukin-1β (IL-1β) production by enzyme-linked immunosorbent assay. Eighteen hours after MSU crystal administration in vivo, TGFβ1 levels were elevated in peritoneal lavage fluids, and a significant number of peritoneal neutrophils were TGFβ1+. Purified blood or peritoneal neutrophils cultured ex vivo showed TGFβ1+ neutrophils coexpressing the apoptosis marker caspase 3 and increased TGFβ1 production, both of which dropped following inhibition of apoptosis. Live neutrophils that had phagocytosed apoptotic neutrophils showed greatest TGFβ1 expression. Superoxide production by purified MSU crystal-recruited neutrophils ex vivo was enhanced by anti-TGFβ1 antibody treatment. Neutrophils purified from the peritoneum of MSU crystal-challenged mice treated with anti-TGFβ1 antibody produced elevated levels of superoxide, but neutrophil IL-1β production was unaffected. Neutrophil cannibalism and TGFβ1 production have the potential to make a significant contribution to the controlled resolution of neutrophil-driven inflammatory diseases such as gout. Copyright © 2013 by the American College of Rheumatology.

Citation

Stefanie Steiger, Jacquie L Harper. Neutrophil cannibalism triggers transforming growth factor β1 production and self regulation of neutrophil inflammatory function in monosodium urate monohydrate crystal-induced inflammation in mice. Arthritis and rheumatism. 2013 Mar;65(3):815-23