Nrf2 downregulates zymosan-induced neutrophil activation and modulates migration

Doumet Georges Helou,Vanessa Granger,Sarah Braham,Marc Pallardy,Saadia Kerdine-Römer,Sylvie Chollet-Martin,Luc De Chaisemartin,Marie-Hélène Damien

doi:10.1371/journal.pone.0216465

Abstract

Polymorphonuclear neutrophils (PMNs) are the first line of defense against pathogens and their activation needs to be tightly regulated in order to limit deleterious effects. Nrf2 (Nuclear factor (erythroïd-derived 2)-like 2) transcription factor regulates oxidative stress and/or represses inflammation in various cells such as dendritic cells or macrophages. However, its involvement in PMN biology is still unclear. Using Nrf2 KO mice, we thus aimed to investigate the protective role of Nrf2 in various PMN functions such as oxidative burst, netosis, migration, cytokine production and phagocytosis, mainly in response to zymosan. We found that zymosan induced Nrf2 accumulation in PMNs leading to the upregulation of some target genes including Hmox-1, Nqo1 and Cat. Nrf2 was able to decrease zymosan-induced PMN oxidative burst; sulforaphane-induced Nrf2 hyperexpression confirmed its implication. Tnfα, Ccl3 and Cxcl2 gene transcription was decreased in zymosan-stimulated Nrf2 KO PMNs, suggesting a role for Nrf2 in the regulation of proinflammatory cytokine production. However, Nrf2 was not involved in phagocytosis. Finally, spontaneous migration of Nrf2 KO PMNs was lower than that of WT PMNs. Moreover, in response to low concentrations of CXCL2 or CXCL12, Nrf2 KO PMN migration was decreased despite similar CXCR2 and CXCR4 expression and ATP levels in PMNs from both genotypes. Nrf2 thus seems to be required for an optimal migration. Altogether these results suggest that Nrf2 has a protective role in several PMN functions. In particular, it downregulates their activation in response to zymosan and is required for an adequate migration.

Highlights

Polymorphonuclear neutrophils (PMNs) are the first cells to be mobilized against pathogens present in both blood and tissues
As nuclear factor (erythroïd-derived 2)-like 2 (Nrf2) was highly expressed in wild type (WT) PMNs, we evaluated its accumulation in response to SFN used as a positive control stimulus, or to zymosan a strong PMN stimulus
In this study, using an in vitro model, we found that Nrf2 participates in the regulation of murine bone marrow (BM)-derived PMN response to the fungal stimulus zymosan, via the activation of cytoprotective genes and the downregulation of pro-inflammatory genes

Summary

Introduction

Polymorphonuclear neutrophils (PMNs) are the first cells to be mobilized against pathogens present in both blood and tissues The role of Nrf transcription factor in neutrophil biology oxygenase-1; IL-, Interleukin; KEAP 1, Kelch-like ECH-associated protein 1; MPO, Myeloperoxidase; NET, Neutrophil extracellular traps; NOX2, NADPH oxidase 2; NQO1, NAD(P)H quinone oxidoreductase 1; NRF2, Nuclear factor (erythroïdderived 2)-like 2; PMNs, Polymorphonuclear neutrophils; ROS, Reactive oxygen species; SFN, Sulforaphane; TLR, Toll-like receptor; TNFα, Tumor necrosis factor α. Among the recently described mechanisms, one can emphasize the following: i) myeloperoxidase (MPO), a key PMN enzyme, can decrease mortality in a sepsis model and regulate inflammation [5,6], ii) our group and others have described PMN-induced dendritic cell modulation in particular via NETs [7,8], iii) NADPH oxidase 2 (NOX2) can limit inflammation in some situations [9] iiii) several inhibitory receptors and mediators have been described such as immunoglobulin-like transcript 4 or Glucocorticoïd- Induced Leucine Zipper (GILZ) [10,11]

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