S100A11 (calgizzarin) is released via NETosis in rheumatoid arthritis (RA) and stimulates IL-6 and TNF secretion by neutrophils

Adéla Navrátilová,Karel Pavelka,Claus Henrik Nielsen,Dres Damgaard,Viktor Bečvář,Lucie Andrés Cerezo,Jiří Baloun,Jiří Vencovský,Ladislav Šenolt,David Veigl

doi:10.1038/s41598-021-85561-3

Abstract

S100A11 (calgizzarin), a member of S100 family, is associated with several autoimmune diseases, including rheumatoid arthritis (RA). Neutrophil extracellular traps (NETs) are implicated in the pathogenesis of RA and in the externalization of some S100 family members. Therefore, we aimed to determine the association between S100A11 and NETs in RA. For this purpose, the levels of S100A11 and NETosis markers were detected in the RA synovial fluid by immunoassays. The expression of S100A11 by neutrophils in the RA synovial tissue was assessed. Neutrophils isolated from peripheral blood were exposed to S100A11 or stimulated to release NETs. The levels of NETosis- and inflammation-associated proteins were analysed by immunoassays. NETs were visualized by immunofluorescence. We showed that S100A11 was expressed by the neutrophils in the RA synovial tissue. Moreover, S100A11 in the RA synovial fluid correlated with several NETosis markers. In vitro, S100A11 was abundantly released by neutrophils undergoing NETosis compared to untreated cells (p < 0.001). Extracellular S100A11 increased the secretion of IL-6 (p < 0.05) and TNF (p < 0.05) by neutrophils but did not induce NETosis. This study demonstrates, for the first time, that the release of S100A11 is dependent on NETosis and that extracellular S100A11 augments the inflammatory response by inducing pro-inflammatory cytokines in neutrophils.

Highlights

We demonstrated that myeloperoxidase (MPO) -positive neutrophils infiltrating the Rheumatoid arthritis (RA) synovial tissue expressed S100A11 (Fig. 1)
In order to determine if S100A11 was released from neutrophils into the extracellular space we analysed the levels of S100A11 in the supernatants from neutrophils isolated from peripheral blood transefered into in vitro conditions
Synovial fluid S100A11 is associated with the anti‐CCP positivity and with the markers of NETosis in RA patients

Summary

Introduction

Rheumatoid arthritis (RA) is a chronic, immune-mediated, systemic disease characterized by persistent synovial inflammation that leads to irreversible structural damage and joint failure. Both genetic and environmental factors contribute to an increased risk for RA development. Recent studies indicate that the components of NETs, such as nuclear material and granular and cytoplasmic proteins, serve as mechanism of pathogen clearance and can act as damage-associated molecular patterns (DAMPs)[10,11], thereby augmenting inflammation or inducing further NETosis in a positive-feedback loop[11,12].

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