Neutrophil extracellular traps activate NLRP3 in mycoplasma pneumoniae pneumonia

Abstract

Abstract The aim of this study was to investigate the role of neutrophil extracellular traps (NETs) in the pathogenesis of Mycoplasma pneumoniae (MP) pneumonia.The sera of 60 MP pneumonia patients and 20 healthy controls were used to detect the level of cell-free DNA, and citrullinated histone H3(Cit-H3)and compared with the clinical characteristics of MP pneumonia patients. Additionally, community-acquired respiratory distress syndrome (CARDS) induced NETs formation and activation of NLRP3 inflammasomes in vitro and in vivo was analyzed. The levels of cell-free DNA and Cit-H3 were significantly increased in the patients with MP pneumonia. Furthermore, cell-free DNA strongly correlated with Cit-H3 and lactate dehydrogenase (LDH). Importantly, both cell-free DNA and LDH were higher in hospitalized patients with severity than those without severity. In addition, CARDS toxin could induce the NETs formation in vitro and in vivo. Finally, we found that Dnase I insignificantly attenuated the higher levels of Cit-H3, and up-regulation of interleukin-1β (IL-1β) and interleukin-18 (IL-18). At the same time, it can down-regulated the expression of NLRP3 and Caspase1(p20) in the lung tissues.These findings illustrate a new mechanism by which NETs contributed to the activation of NLRP3 inflammasome in MP pneumonia.