Plasmin and plasminogen prevent sepsis severity by reducing neutrophil extracellular traps and systemic inflammation
Juliana P. Vago, Isabella Zaidan, Luiza O. Perucci, Larissa Froede Brito, Lívia C.R. Teixeira, Camila Meirelles Souza Silva, Thaís C. Miranda, Eliza M. Melo, Alexandre S. Bruno, Celso Martins Queiroz-Junior, Michelle A. Sugimoto, Luciana P. Tavares, Laís C. Grossi, Isabela N. Borges, Ayda Henriques Schneider, Nagyung Baik, Ayda H. Schneider, André Talvani, Raphael G. Ferreira, José C. Alves-Filho, Vandack Nobre, Mauro M. Teixeira, Robert J. Parmer, Lindsey A. Miles, Lirlândia P. Sousa
Juliana P. Vago, Isabella Zaidan, Luiza O. Perucci, Larissa Froede Brito, Lívia C.R. Teixeira, Camila Meirelles Souza Silva, Thaís C. Miranda, Eliza M. Melo, Alexandre S. Bruno, Celso Martins Queiroz-Junior, Michelle A. Sugimoto, Luciana P. Tavares, Laís C. Grossi, Isabela N. Borges, Ayda Henriques Schneider, Nagyung Baik, Ayda H. Schneider, André Talvani, Raphael G. Ferreira, José C. Alves-Filho, Vandack Nobre, Mauro M. Teixeira, Robert J. Parmer, Lindsey A. Miles, Lirlândia P. Sousa
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Research Article Infectious disease

Plasmin and plasminogen prevent sepsis severity by reducing neutrophil extracellular traps and systemic inflammation

Abstract

Sepsis is a lethal syndrome characterized by systemic inflammation and abnormal coagulation. Despite therapeutic advances, sepsis mortality remains substantially high. Herein, we investigated the role of the plasminogen/plasmin (Plg/Pla) system during sepsis. Plasma levels of Plg were significantly lower in mice subjected to severe compared with nonsevere sepsis, whereas systemic levels of IL-6, a marker of sepsis severity, were higher in severe sepsis. Plg levels correlated negatively with IL-6 in both septic mice and patients, whereas plasminogen activator inhibitor-1 levels correlated positively with IL-6. Plg deficiency render mice susceptible to nonsevere sepsis induced by cecal ligation and puncture (CLP), resulting in greater numbers of neutrophils and M1 macrophages, liver fibrin(ogen) deposition, lower efferocytosis, and increased IL-6 and neutrophil extracellular trap (NET) release associated with organ damage. Conversely, inflammatory features, fibrin(ogen), and organ damage were substantially reduced, and efferocytosis was increased by exogenous Pla given during CLP- and LPS-induced endotoxemia. Plg or Pla protected mice from sepsis-induced lethality and enhanced the protective effect of antibiotics. Mechanistically, Plg/Pla–afforded protection was associated with regulation of NET release, requiring Pla-protease activity and lysine binding sites. Plg/Pla are important host-protective players during sepsis, controlling local and systemic inflammation and collateral organ damage.

Authors

Juliana P. Vago, Isabella Zaidan, Luiza O. Perucci, Larissa Froede Brito, Lívia C.R. Teixeira, Camila Meirelles Souza Silva, Thaís C. Miranda, Eliza M. Melo, Alexandre S. Bruno, Celso Martins Queiroz-Junior, Michelle A. Sugimoto, Luciana P. Tavares, Laís C. Grossi, Isabela N. Borges, Ayda Henriques Schneider, Nagyung Baik, Ayda H. Schneider, André Talvani, Raphael G. Ferreira, José C. Alves-Filho, Vandack Nobre, Mauro M. Teixeira, Robert J. Parmer, Lindsey A. Miles, Lirlândia P. Sousa

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Figure 5

Effect of Plg depletion on lethality and of Pla treatment on inflammatory parameters during endotoxemia induced by LPS.

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Effect of Plg depletion on lethality and of Pla treatment on inflammator...
Plg+/+ and Plg–/– mice were subjected to an i.p. injection of LPS (10 mg/kg). (A) The survival rates (n = 8 mice) were monitored for 6 days. #P < 0.05 when comparing Plg+/+ and Plg–/– mice by log-rank test (survival curves). WT C57BL/6J mice were subjected to an i.p. injection of LPS (10 mg/kg) and then treated with Pla (10 μg/mouse i.p.) 3 hours later. Cells present in the peritoneal cavity were harvested 12 hours after LPS injection. (B–D) The number of total cells, mononuclear cells, and neutrophils (B), percentage of apoptotic neutrophils (C), and efferocytosis (D) were evaluated by counting cytospin slides treated with May–Grünwald–Giemsa stain. (E and F) The levels of TNF, IL-10, IL-6, and CXCL-1 were quantified in cell-free peritoneal lavages (E) and plasma (F), by ELISA. (G–I) The ALT activity (G), and creatinine (H) and fibrinogen (I) levels were measured in plasma. (J) Expression of fibrin(ogen) in the liver was determined by Western blotting (n = 3) with anti–β-actin used as loading control. (K) Densitometric analysis is also represented. (L and M) MPO (L) and NAG (M) activities were measured in the liver homogenates. Results are shown as the mean ± SEM of 5–7 mice per group. The experiments were performed 3 times with similar results. *P < 0.05, ***P < 0.001 when comparing PBS-injected mice with LPS-injected mice. P values are indicated in the graphs when comparing vehicle with Pla-treated mice by 1-way ANOVA with post hoc Newman-Keuls (multiple groups) or unpaired 2-tailed Student’s t test (when comparing 2 groups). Outliers were removed from the graphs when detected.