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LPS-induced galectin-3 oligomerization results in enhancement of neutrophil activation.

Fermino ML, Polli CD, Toledo KA, Liu FT, Hsu DK, Roque-Barreira MC, Pereira-da-Silva G, Bernardes ES, Halbwachs-Mecarelli L - PLoS ONE (2011)

Bottom Line: Although it is well established that Gal 3 can interact with LPS, the pathophysiological importance of LPS/Gal 3 interactions is not fully understood.This result emphasizes the importance of an N-terminus-mediated Gal 3 oligomerization induced by its interaction with LPS.Finally we demonstrated that Balb/C mice were more susceptible to LPS-mediated shock when LPS was pretreated with Gal 3.

View Article: PubMed Central - PubMed

Affiliation: Université Paris Descartes, Sorbonne Paris Cité, Paris, France.

ABSTRACT
Galectin-3 (Gal 3) is a glycan-binding protein that can be secreted by activated macrophages and mast cells at inflammation sites and plays an important role in inflammatory diseases caused by Bacteria and their products, such as lipopolysaccharides (LPS). Although it is well established that Gal 3 can interact with LPS, the pathophysiological importance of LPS/Gal 3 interactions is not fully understood. Data presented herein demonstrate for the first time that the interaction of Gal 3, either via its carbohydrate binding C-terminal domain or via its N-terminal part, with LPS from different bacterial strains, enhances the LPS-mediated neutrophil activation in vitro. Gal 3 allowed low LPS concentrations (1 µg/mL without serum, 1 ng/mL with serum) to upregulate CD11b expression and reactive oxygen species (ROS) generation on human neutrophils in vitro and drastically enhanced the binding efficiency of LPS to the neutrophil surface. These effects required LPS preincubation with Gal 3, before neutrophil stimulation and involved specific Gal 3/LPS interaction. A C-terminal Gal-3 fragment, which retains the lectin domain but lacks the N-terminal part, was still able to bind both to Escherichia coli LPS and to neutrophils, but had lost the ability to enhance neutrophil response to LPS. This result emphasizes the importance of an N-terminus-mediated Gal 3 oligomerization induced by its interaction with LPS. Finally we demonstrated that Balb/C mice were more susceptible to LPS-mediated shock when LPS was pretreated with Gal 3. Altogether, these results suggest that multimeric interactions between Gal 3 oligomers and LPS potentiate its pro-inflammatory effects on neutrophils.

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Gal 3/LPS interaction decreases mice resistance to the lethality of LPS.A: Groups of 5 Balb/C mice were challenged with PBS, 6.2, 12.5 or 25 mg/kg of E. coli LPS by intraperitoneal (ip) injection. B: Mice (5 per group) were challenged with 500 µl of PBS, Gal 3 (40 µM), 6.2 mg/kg LPS or with a mixture of LPS (6.2 mg/kg) and Gal 3 (40 µM) preincubated for 15 min. The mortality rate was monitored regularly and represented as percentage of survival. *p<0.05.
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pone-0026004-g007: Gal 3/LPS interaction decreases mice resistance to the lethality of LPS.A: Groups of 5 Balb/C mice were challenged with PBS, 6.2, 12.5 or 25 mg/kg of E. coli LPS by intraperitoneal (ip) injection. B: Mice (5 per group) were challenged with 500 µl of PBS, Gal 3 (40 µM), 6.2 mg/kg LPS or with a mixture of LPS (6.2 mg/kg) and Gal 3 (40 µM) preincubated for 15 min. The mortality rate was monitored regularly and represented as percentage of survival. *p<0.05.

Mentions: Endotoxic shock is the most severe form of LPS-mediated inflammatory disease, which is mainly mediated by an uncontrolled neutrophil activation [32]–[36]. So far we have shown that Gal 3 lowers the activation threshold of LPS-stimulated neutrophils in vitro. We, thus, further explored Gal 3 effect in an in vivo sepsis model. First, in order to determine a suitable concentration of LPS for inducing endotoxemia, mice were challenged with different doses of LPS (Figure 7A). All mice receiving 25 mg/Kg LPS died, while those receiving LPS at 6.2 mg/Kg exhibited 50% survival during a 30-hour period. Therefore, we assessed the influence of Gal 3 on endotoxin-mediated mortality by measuring survival of mice challenged with LPS (6.2 mg/Kg) preincubated with 500 µL of Gal 3 (40 µM) for 15 minutes before the challenge. As shown in figure 7B, all mice receiving PBS or Gal 3 alone survived, while 60% of mice receiving LPS at 6.2 mg/Kg survived up to 30 h past challenge, as expected. Interestingly, all mice challenged with LPS pre-incubated with Gal 3 died within 30 h after challenge. This result suggests that exogenous Gal 3 can enhance the effect of LPS both in vitro and in vivo.


LPS-induced galectin-3 oligomerization results in enhancement of neutrophil activation.

Fermino ML, Polli CD, Toledo KA, Liu FT, Hsu DK, Roque-Barreira MC, Pereira-da-Silva G, Bernardes ES, Halbwachs-Mecarelli L - PLoS ONE (2011)

Gal 3/LPS interaction decreases mice resistance to the lethality of LPS.A: Groups of 5 Balb/C mice were challenged with PBS, 6.2, 12.5 or 25 mg/kg of E. coli LPS by intraperitoneal (ip) injection. B: Mice (5 per group) were challenged with 500 µl of PBS, Gal 3 (40 µM), 6.2 mg/kg LPS or with a mixture of LPS (6.2 mg/kg) and Gal 3 (40 µM) preincubated for 15 min. The mortality rate was monitored regularly and represented as percentage of survival. *p<0.05.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3198732&req=5

pone-0026004-g007: Gal 3/LPS interaction decreases mice resistance to the lethality of LPS.A: Groups of 5 Balb/C mice were challenged with PBS, 6.2, 12.5 or 25 mg/kg of E. coli LPS by intraperitoneal (ip) injection. B: Mice (5 per group) were challenged with 500 µl of PBS, Gal 3 (40 µM), 6.2 mg/kg LPS or with a mixture of LPS (6.2 mg/kg) and Gal 3 (40 µM) preincubated for 15 min. The mortality rate was monitored regularly and represented as percentage of survival. *p<0.05.
Mentions: Endotoxic shock is the most severe form of LPS-mediated inflammatory disease, which is mainly mediated by an uncontrolled neutrophil activation [32]–[36]. So far we have shown that Gal 3 lowers the activation threshold of LPS-stimulated neutrophils in vitro. We, thus, further explored Gal 3 effect in an in vivo sepsis model. First, in order to determine a suitable concentration of LPS for inducing endotoxemia, mice were challenged with different doses of LPS (Figure 7A). All mice receiving 25 mg/Kg LPS died, while those receiving LPS at 6.2 mg/Kg exhibited 50% survival during a 30-hour period. Therefore, we assessed the influence of Gal 3 on endotoxin-mediated mortality by measuring survival of mice challenged with LPS (6.2 mg/Kg) preincubated with 500 µL of Gal 3 (40 µM) for 15 minutes before the challenge. As shown in figure 7B, all mice receiving PBS or Gal 3 alone survived, while 60% of mice receiving LPS at 6.2 mg/Kg survived up to 30 h past challenge, as expected. Interestingly, all mice challenged with LPS pre-incubated with Gal 3 died within 30 h after challenge. This result suggests that exogenous Gal 3 can enhance the effect of LPS both in vitro and in vivo.

Bottom Line: Although it is well established that Gal 3 can interact with LPS, the pathophysiological importance of LPS/Gal 3 interactions is not fully understood.This result emphasizes the importance of an N-terminus-mediated Gal 3 oligomerization induced by its interaction with LPS.Finally we demonstrated that Balb/C mice were more susceptible to LPS-mediated shock when LPS was pretreated with Gal 3.

View Article: PubMed Central - PubMed

Affiliation: Université Paris Descartes, Sorbonne Paris Cité, Paris, France.

ABSTRACT
Galectin-3 (Gal 3) is a glycan-binding protein that can be secreted by activated macrophages and mast cells at inflammation sites and plays an important role in inflammatory diseases caused by Bacteria and their products, such as lipopolysaccharides (LPS). Although it is well established that Gal 3 can interact with LPS, the pathophysiological importance of LPS/Gal 3 interactions is not fully understood. Data presented herein demonstrate for the first time that the interaction of Gal 3, either via its carbohydrate binding C-terminal domain or via its N-terminal part, with LPS from different bacterial strains, enhances the LPS-mediated neutrophil activation in vitro. Gal 3 allowed low LPS concentrations (1 µg/mL without serum, 1 ng/mL with serum) to upregulate CD11b expression and reactive oxygen species (ROS) generation on human neutrophils in vitro and drastically enhanced the binding efficiency of LPS to the neutrophil surface. These effects required LPS preincubation with Gal 3, before neutrophil stimulation and involved specific Gal 3/LPS interaction. A C-terminal Gal-3 fragment, which retains the lectin domain but lacks the N-terminal part, was still able to bind both to Escherichia coli LPS and to neutrophils, but had lost the ability to enhance neutrophil response to LPS. This result emphasizes the importance of an N-terminus-mediated Gal 3 oligomerization induced by its interaction with LPS. Finally we demonstrated that Balb/C mice were more susceptible to LPS-mediated shock when LPS was pretreated with Gal 3. Altogether, these results suggest that multimeric interactions between Gal 3 oligomers and LPS potentiate its pro-inflammatory effects on neutrophils.

Show MeSH
Related in: MedlinePlus