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 4

Effect of Pla treatment on inflammatory parameters and survival rates during severe sepsis induced by CLP.

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Effect of Pla treatment on inflammatory parameters and survival rates du...
WT C57BL/6J mice (n = 4–8) were subjected to severe (18G needle) CLP and then treated with Pla (10 μg/mouse i.p.) 3 hours later. Cells present in the peritoneal cavity were harvested 12 hours after CLP. (A and C) The number of total cells, mononuclear cells, and neutrophils (A), and frequency of efferocytosis (C) were evaluated by counting cytospin slides treated with May–Grünwald–Giemsa stain. (B) The number of M1 (F4/80low GR1+ CD11bmed) macrophages were determined by flow cytometry. (D and E) The levels of TNF, IL-10, IL-6, and CXCL1 were quantified in cell-free peritoneal lavages (D) and plasma (E), respectively, by ELISA. (F) Platelets counted from blood samples. (G and H)The peritoneal fluid (G) and blood (H) samples were plated in brain–heart infusion medium for the analysis of bacterial load. (I) ALT activity was measured from plasma. Results are shown as the mean ± SEM or median of 4–8 mice per group. The experiments were performed 3 times with similar results. *P < 0.05, **P < 0.01, or ***P < 0.001 when comparing the sham group with the CLP group by 1-way ANOVA with post hoc Newman-Keuls (multiple groups) or unpaired 2-tailed Student’s t test (when comparing 2 groups). P values are indicated in the graphs when comparing vehicle with Pla-treated mice. Outliers were removed from the graphs when detected. In the survival experiments, C57BL/6J mice (n = 7) were subjected to severe (18G needle) CLP and treated with Pla (10 μg/mouse, i.p.), Plg (10 μg/mouse, i.p.), imipenem (IMI; 30 mg/kg, i.p.), or a combination of both (Plg 10 μg/mouse i.p. + IMI 30 mg/k, i.p.) after 3 and 12 hours of sepsis induction. (J) The survival rates were monitored for 6 days. The experiment was performed 2 times with similar results. *P < 0.05 when comparing vehicle-treated mice with Pla-, Plg-, or IMI-treated mice. **P < 0.01 when comparing vehicle-treated mice with Plg- + IMI-treated mice by log-rank test.