Exosomal miR-30d-5p of neutrophils induces M1 macrophage polarization and primes macrophage pyroptosis in sepsis-related acute lung injury

Crit Care. 2021 Oct 12;25(1):356. doi: 10.1186/s13054-021-03775-3.

Abstract

Background: Polymorphonuclear neutrophils (PMNs) play an important role in sepsis-related acute lung injury (ALI). Accumulating evidence suggests PMN-derived exosomes as a new subcellular entity acting as a fundamental link between PMN-driven inflammation and tissue damage. However, the role of PMN-derived exosomes in sepsis-related ALI and the underlying mechanisms remains unclear.

Methods: Tumor necrosis factor-α (TNF-α), a key regulator of innate immunity in sepsis-related ALI, was used to stimulate PMNs from healthy C57BL/6J mice in vitro. Exosomes isolated from the supernatant were injected to C57BL/6J wild-type mice intraperitoneally (i.p.) and then examined for lung inflammation, macrophage (Mϕ) polarization and pyroptosis. In vitro co-culture system was applied where the mouse Raw264.7 macrophages or bone marrow-derived macrophages (BMDMs) were co-cultured with PMN-derived exosomes to further confirm the results of in vivo animal study and explore the potential mechanisms involved.

Results: Exosomes released by TNF-α-stimulated PMNs (TNF-Exo) promoted M1 macrophage activation after in vivo i.p. injection or in vitro co-culture. In addition, TNF-Exo primed macrophage for pyroptosis by upregulating NOD-like receptor 3 (NLRP3) inflammasome expression through nuclear factor κB (NF-κB) signaling pathway. Mechanistic studies demonstrated that miR-30d-5p mediated the function of TNF-Exo by targeting suppressor of cytokine signaling (SOCS-1) and sirtuin 1 (SIRT1) in macrophages. Furthermore, intravenous administration of miR-30d-5p inhibitors significantly decreased TNF-Exo or cecal ligation and puncture (CLP)-induced M1 macrophage activation and macrophage death in the lung, as well as the histological lesions.

Conclusions: The present study demonstrated that exosomal miR-30d-5p from PMNs contributed to sepsis-related ALI by inducing M1 macrophage polarization and priming macrophage pyroptosis through activating NF-κB signaling. These findings suggest a novel mechanism of PMN-Mϕ interaction in sepsis-related ALI, which may provide new therapeutic strategies in sepsis patients.

Keywords: Exosomes; Macrophage; Neutrophil; Pyroptosis; Sepsis-related acute lung injury; miR-30d-5p.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acute Lung Injury* / etiology
  • Animals
  • Humans
  • Macrophage Activation
  • Macrophages
  • Mice
  • Mice, Inbred C57BL
  • MicroRNAs*
  • NF-kappa B
  • Neutrophils
  • Pyroptosis
  • Sepsis* / complications
  • Tumor Necrosis Factor-alpha

Substances

  • MicroRNAs
  • NF-kappa B
  • Tumor Necrosis Factor-alpha