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Shiga toxin and lipopolysaccharide induce platelet-leukocyte aggregates and tissue factor release, a thrombotic mechanism in hemolytic uremic syndrome.

Ståhl AL, Sartz L, Nelsson A, Békássy ZD, Karpman D - PLoS ONE (2009)

Bottom Line: Stx and LPS in combination had a more pronounced effect on platelet-monocyte aggregate formation, and TF expression on these aggregates, than each virulence factor alone.Blood cell aggregates, microparticles, and TF decreased upon recovery.By triggering TF release in the circulation, Stx and LPS can induce a prothrombotic state contributing to the pathogenesis of HUS.

View Article: PubMed Central - PubMed

Affiliation: Department of Pediatrics, Clinical Sciences Lund, Lund University, Lund, Sweden.

ABSTRACT

Background: Aggregates formed between leukocytes and platelets in the circulation lead to release of tissue factor (TF)-bearing microparticles contributing to a prothrombotic state. As enterohemorrhagic Escherichia coli (EHEC) may cause hemolytic uremic syndrome (HUS), in which microthrombi cause tissue damage, this study investigated whether the interaction between blood cells and EHEC virulence factors Shiga toxin (Stx) and lipopolysaccharide (LPS) led to release of TF.

Methodology/principal findings: The interaction between Stx or LPS and blood cells induced platelet-leukocyte aggregate formation and tissue factor (TF) release, as detected by flow cytometry in whole blood. O157LPS was more potent than other LPS serotypes. Aggregates formed mainly between monocytes and platelets and less so between neutrophils and platelets. Stimulated blood cells in complex expressed activation markers, and microparticles were released. Microparticles originated mainly from platelets and monocytes and expressed TF. TF-expressing microparticles, and functional TF in plasma, increased when blood cells were simultaneously exposed to the EHEC virulence factors and high shear stress. Stx and LPS in combination had a more pronounced effect on platelet-monocyte aggregate formation, and TF expression on these aggregates, than each virulence factor alone. Whole blood and plasma from HUS patients (n = 4) were analyzed. All patients had an increase in leukocyte-platelet aggregates, mainly between monocytes and platelets, on which TF was expressed during the acute phase of disease. Patients also exhibited an increase in microparticles, mainly originating from platelets and monocytes, bearing surface-bound TF, and functional TF was detected in their plasma. Blood cell aggregates, microparticles, and TF decreased upon recovery.

Conclusions/significance: By triggering TF release in the circulation, Stx and LPS can induce a prothrombotic state contributing to the pathogenesis of HUS.

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Related in: MedlinePlus

Platelet-monocyte and platelet-neutrophil aggregate formation and TF expression induced by shear and Stx2 and/or LPS.Stx2, O157:H7LPS, O111:B4LPS (both LPS serogroups at 1 µg/mL) or a combination of Stx2 and LPS were added to whole blood immediately before perfusion of whole blood through a flow chamber system and aggregate formation and tissue factor expression determined by flow cytometry. (A) Stx2 and/or LPS induced platelet-monocyte aggregate formation particularly at shear rates between 1000–2000 s−1 (light bars). (B) Aggregate formation between platelets and neutrophils increased minimally by addition of Stx2 or LPS at both low (100–340 s−1) and high shear rates as compared to PBS-treated samples. (C) Stx2 or LPS induced TF expression on platelet-monocyte aggregates at low shear rates which increased even more at high shear rates. Expression increased markedly in Stx2/LPS stimulated samples at higher shear rates. (D) Stx2 and/or LPS induced only a weak increase in TF expression on platelet-neutrophil aggregates. Higher shear rates did not induce more TF expression. Data are expressed as mean±standard deviation (n = 3). Statistical comparisons were not carried out as only three experiments were performed due to the large amounts of blood required.
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pone-0006990-g006: Platelet-monocyte and platelet-neutrophil aggregate formation and TF expression induced by shear and Stx2 and/or LPS.Stx2, O157:H7LPS, O111:B4LPS (both LPS serogroups at 1 µg/mL) or a combination of Stx2 and LPS were added to whole blood immediately before perfusion of whole blood through a flow chamber system and aggregate formation and tissue factor expression determined by flow cytometry. (A) Stx2 and/or LPS induced platelet-monocyte aggregate formation particularly at shear rates between 1000–2000 s−1 (light bars). (B) Aggregate formation between platelets and neutrophils increased minimally by addition of Stx2 or LPS at both low (100–340 s−1) and high shear rates as compared to PBS-treated samples. (C) Stx2 or LPS induced TF expression on platelet-monocyte aggregates at low shear rates which increased even more at high shear rates. Expression increased markedly in Stx2/LPS stimulated samples at higher shear rates. (D) Stx2 and/or LPS induced only a weak increase in TF expression on platelet-neutrophil aggregates. Higher shear rates did not induce more TF expression. Data are expressed as mean±standard deviation (n = 3). Statistical comparisons were not carried out as only three experiments were performed due to the large amounts of blood required.

Mentions: Perfusion of whole blood at shear rates between 100–340 s−1 or 1000–2000 s−1 with Stx2, O157LPS (1 µg/mL) or O157LPS/Stx2 through a parallel plate flow chamber increased platelet-monocyte aggregates considerably (Figure 6A) compared to PBS-stimulated whole blood. Similarly, O111:B4LPS alone or in combination with Stx2 increased platelet-monocyte aggregates. Higher shear rates (1000–2000 s−1) induced more platelet-monocyte aggregate formation in the presence of Stx2 or O157LPS than lower shear rates (Figure 6A). Notably, the combination of Stx2/O157LPS at the lower shear rate increased platelet-monocyte aggregates two-fold in comparison to each agonist alone. Combination of low or high shear and Stx2, O157LPS or both simultaneously induced only a slight increase in platelet-neutrophil aggregates (Figure 6B).


Shiga toxin and lipopolysaccharide induce platelet-leukocyte aggregates and tissue factor release, a thrombotic mechanism in hemolytic uremic syndrome.

Ståhl AL, Sartz L, Nelsson A, Békássy ZD, Karpman D - PLoS ONE (2009)

Platelet-monocyte and platelet-neutrophil aggregate formation and TF expression induced by shear and Stx2 and/or LPS.Stx2, O157:H7LPS, O111:B4LPS (both LPS serogroups at 1 µg/mL) or a combination of Stx2 and LPS were added to whole blood immediately before perfusion of whole blood through a flow chamber system and aggregate formation and tissue factor expression determined by flow cytometry. (A) Stx2 and/or LPS induced platelet-monocyte aggregate formation particularly at shear rates between 1000–2000 s−1 (light bars). (B) Aggregate formation between platelets and neutrophils increased minimally by addition of Stx2 or LPS at both low (100–340 s−1) and high shear rates as compared to PBS-treated samples. (C) Stx2 or LPS induced TF expression on platelet-monocyte aggregates at low shear rates which increased even more at high shear rates. Expression increased markedly in Stx2/LPS stimulated samples at higher shear rates. (D) Stx2 and/or LPS induced only a weak increase in TF expression on platelet-neutrophil aggregates. Higher shear rates did not induce more TF expression. Data are expressed as mean±standard deviation (n = 3). Statistical comparisons were not carried out as only three experiments were performed due to the large amounts of blood required.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2735777&req=5

pone-0006990-g006: Platelet-monocyte and platelet-neutrophil aggregate formation and TF expression induced by shear and Stx2 and/or LPS.Stx2, O157:H7LPS, O111:B4LPS (both LPS serogroups at 1 µg/mL) or a combination of Stx2 and LPS were added to whole blood immediately before perfusion of whole blood through a flow chamber system and aggregate formation and tissue factor expression determined by flow cytometry. (A) Stx2 and/or LPS induced platelet-monocyte aggregate formation particularly at shear rates between 1000–2000 s−1 (light bars). (B) Aggregate formation between platelets and neutrophils increased minimally by addition of Stx2 or LPS at both low (100–340 s−1) and high shear rates as compared to PBS-treated samples. (C) Stx2 or LPS induced TF expression on platelet-monocyte aggregates at low shear rates which increased even more at high shear rates. Expression increased markedly in Stx2/LPS stimulated samples at higher shear rates. (D) Stx2 and/or LPS induced only a weak increase in TF expression on platelet-neutrophil aggregates. Higher shear rates did not induce more TF expression. Data are expressed as mean±standard deviation (n = 3). Statistical comparisons were not carried out as only three experiments were performed due to the large amounts of blood required.
Mentions: Perfusion of whole blood at shear rates between 100–340 s−1 or 1000–2000 s−1 with Stx2, O157LPS (1 µg/mL) or O157LPS/Stx2 through a parallel plate flow chamber increased platelet-monocyte aggregates considerably (Figure 6A) compared to PBS-stimulated whole blood. Similarly, O111:B4LPS alone or in combination with Stx2 increased platelet-monocyte aggregates. Higher shear rates (1000–2000 s−1) induced more platelet-monocyte aggregate formation in the presence of Stx2 or O157LPS than lower shear rates (Figure 6A). Notably, the combination of Stx2/O157LPS at the lower shear rate increased platelet-monocyte aggregates two-fold in comparison to each agonist alone. Combination of low or high shear and Stx2, O157LPS or both simultaneously induced only a slight increase in platelet-neutrophil aggregates (Figure 6B).

Bottom Line: Stx and LPS in combination had a more pronounced effect on platelet-monocyte aggregate formation, and TF expression on these aggregates, than each virulence factor alone.Blood cell aggregates, microparticles, and TF decreased upon recovery.By triggering TF release in the circulation, Stx and LPS can induce a prothrombotic state contributing to the pathogenesis of HUS.

View Article: PubMed Central - PubMed

Affiliation: Department of Pediatrics, Clinical Sciences Lund, Lund University, Lund, Sweden.

ABSTRACT

Background: Aggregates formed between leukocytes and platelets in the circulation lead to release of tissue factor (TF)-bearing microparticles contributing to a prothrombotic state. As enterohemorrhagic Escherichia coli (EHEC) may cause hemolytic uremic syndrome (HUS), in which microthrombi cause tissue damage, this study investigated whether the interaction between blood cells and EHEC virulence factors Shiga toxin (Stx) and lipopolysaccharide (LPS) led to release of TF.

Methodology/principal findings: The interaction between Stx or LPS and blood cells induced platelet-leukocyte aggregate formation and tissue factor (TF) release, as detected by flow cytometry in whole blood. O157LPS was more potent than other LPS serotypes. Aggregates formed mainly between monocytes and platelets and less so between neutrophils and platelets. Stimulated blood cells in complex expressed activation markers, and microparticles were released. Microparticles originated mainly from platelets and monocytes and expressed TF. TF-expressing microparticles, and functional TF in plasma, increased when blood cells were simultaneously exposed to the EHEC virulence factors and high shear stress. Stx and LPS in combination had a more pronounced effect on platelet-monocyte aggregate formation, and TF expression on these aggregates, than each virulence factor alone. Whole blood and plasma from HUS patients (n = 4) were analyzed. All patients had an increase in leukocyte-platelet aggregates, mainly between monocytes and platelets, on which TF was expressed during the acute phase of disease. Patients also exhibited an increase in microparticles, mainly originating from platelets and monocytes, bearing surface-bound TF, and functional TF was detected in their plasma. Blood cell aggregates, microparticles, and TF decreased upon recovery.

Conclusions/significance: By triggering TF release in the circulation, Stx and LPS can induce a prothrombotic state contributing to the pathogenesis of HUS.

Show MeSH
Related in: MedlinePlus