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Toll-like receptor 9 promotes cardiac inflammation and heart failure during polymicrobial sepsis.

Lohner R, Schwederski M, Narath C, Klein J, Duerr GD, Torno A, Knuefermann P, Hoeft A, Baumgarten G, Meyer R, Boehm O - Mediators Inflamm. (2013)

Bottom Line: CASP led to continuous release of bacteria into the peritoneal cavity, an increase of cytokines, and differential regulation of receptors of innate immunity in the heart.This coincided with reduced cardiomyocyte sarcomere shortening.TLR9 deficiency resulted in significant reduction of cardiac inflammation and a sustained heart function.

View Article: PubMed Central - PubMed

Affiliation: Institute for Physiology II, University of Bonn, Nussallee 11, 53115 Bonn, Germany.

ABSTRACT

Background: Aim was to elucidate the role of toll-like receptor 9 (TLR9) in cardiac inflammation and septic heart failure in a murine model of polymicrobial sepsis.

Methods: Sepsis was induced via colon ascendens stent peritonitis (CASP) in C57BL/6 wild-type (WT) and TLR9-deficient (TLR9-D) mice. Bacterial load in the peritoneal cavity and cardiac expression of inflammatory mediators were determined at 6, 12, 18, 24, and 36 h. Eighteen hours after CASP cardiac function was monitored in vivo. Sarcomere length of isolated cardiomyocytes was measured at 0.5 to 10 Hz after incubation with heat-inactivated bacteria.

Results: CASP led to continuous release of bacteria into the peritoneal cavity, an increase of cytokines, and differential regulation of receptors of innate immunity in the heart. Eighteen hours after CASP WT mice developed septic heart failure characterised by reduction of end-systolic pressure, stroke volume, cardiac output, and parameters of contractility. This coincided with reduced cardiomyocyte sarcomere shortening. TLR9 deficiency resulted in significant reduction of cardiac inflammation and a sustained heart function. This was consistent with reduced mortality in TLR9-D compared to WT mice.

Conclusions: In polymicrobial sepsis TLR9 signalling is pivotal to cardiac inflammation and septic heart failure.

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Related in: MedlinePlus

Protein levels of cytokines and cardiomyocyte contractility. (a), (b) Protein levels of proinflammatory cytokines were analysed via ELISA 18 h after CASP in hearts of WT Sham, WT CASP, and TLR9-D CASP mice (*:P < 0.05;  n = 8/group; mean  ±  SEM). (c), (d) Original recordings of sarcomere shortenings of isolated cardiomyocytes incubated in culture medium (CM) or culture medium + heat-inactivated bacteria (HIB) stimulated at 4 Hz. (e) Plot of averaged sarcomere-shortening amplitude versus stimulation frequency recorded directly after isolation (WT control) or after incubation with culture medium (WT CM) or with CM + HIB (#:P < 0.05 WT HIB versus WT control; *:P < 0.05 WT HIB versus WT CM;  n = 6–12/group; mean  ±  SEM). (f) Comparison of sarcomere-shortening amplitude at 4 Hz stimulation frequency of WT control cardiomyocytes and WT and TLR9-D cardiomyocytes incubated in HIB for 5–7 h  (n > 5; *:P < 0.05; mean  ±  SEM).
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fig5: Protein levels of cytokines and cardiomyocyte contractility. (a), (b) Protein levels of proinflammatory cytokines were analysed via ELISA 18 h after CASP in hearts of WT Sham, WT CASP, and TLR9-D CASP mice (*:P < 0.05;  n = 8/group; mean  ±  SEM). (c), (d) Original recordings of sarcomere shortenings of isolated cardiomyocytes incubated in culture medium (CM) or culture medium + heat-inactivated bacteria (HIB) stimulated at 4 Hz. (e) Plot of averaged sarcomere-shortening amplitude versus stimulation frequency recorded directly after isolation (WT control) or after incubation with culture medium (WT CM) or with CM + HIB (#:P < 0.05 WT HIB versus WT control; *:P < 0.05 WT HIB versus WT CM;  n = 6–12/group; mean  ±  SEM). (f) Comparison of sarcomere-shortening amplitude at 4 Hz stimulation frequency of WT control cardiomyocytes and WT and TLR9-D cardiomyocytes incubated in HIB for 5–7 h  (n > 5; *:P < 0.05; mean  ±  SEM).

Mentions: To further validate the mRNA results of proinflammatory cytokines ELISAs of IL-1β and IL-6 were performed 18 h after CASP. Like the mRNA expression also the protein levels of the investigated cytokines in WT animals were significantly elevated after CASP surgery in WT mice (both versus WT Sham: IL-1β: P = 0.0221, Figure 5(a); IL-6: P = 0.0083, Figure 5(b)). In TLR9-D CASP mice protein concentrations of both proinflammatory cytokines stayed at the level of WT Sham hearts and were significantly lower than in WT CASP hearts (both versus WT CASP: IL-1β: P = 0.0281, Figure 5(a); IL-6: P = 0.0024, Figure 5(b)).


Toll-like receptor 9 promotes cardiac inflammation and heart failure during polymicrobial sepsis.

Lohner R, Schwederski M, Narath C, Klein J, Duerr GD, Torno A, Knuefermann P, Hoeft A, Baumgarten G, Meyer R, Boehm O - Mediators Inflamm. (2013)

Protein levels of cytokines and cardiomyocyte contractility. (a), (b) Protein levels of proinflammatory cytokines were analysed via ELISA 18 h after CASP in hearts of WT Sham, WT CASP, and TLR9-D CASP mice (*:P < 0.05;  n = 8/group; mean  ±  SEM). (c), (d) Original recordings of sarcomere shortenings of isolated cardiomyocytes incubated in culture medium (CM) or culture medium + heat-inactivated bacteria (HIB) stimulated at 4 Hz. (e) Plot of averaged sarcomere-shortening amplitude versus stimulation frequency recorded directly after isolation (WT control) or after incubation with culture medium (WT CM) or with CM + HIB (#:P < 0.05 WT HIB versus WT control; *:P < 0.05 WT HIB versus WT CM;  n = 6–12/group; mean  ±  SEM). (f) Comparison of sarcomere-shortening amplitude at 4 Hz stimulation frequency of WT control cardiomyocytes and WT and TLR9-D cardiomyocytes incubated in HIB for 5–7 h  (n > 5; *:P < 0.05; mean  ±  SEM).
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3713595&req=5

fig5: Protein levels of cytokines and cardiomyocyte contractility. (a), (b) Protein levels of proinflammatory cytokines were analysed via ELISA 18 h after CASP in hearts of WT Sham, WT CASP, and TLR9-D CASP mice (*:P < 0.05;  n = 8/group; mean  ±  SEM). (c), (d) Original recordings of sarcomere shortenings of isolated cardiomyocytes incubated in culture medium (CM) or culture medium + heat-inactivated bacteria (HIB) stimulated at 4 Hz. (e) Plot of averaged sarcomere-shortening amplitude versus stimulation frequency recorded directly after isolation (WT control) or after incubation with culture medium (WT CM) or with CM + HIB (#:P < 0.05 WT HIB versus WT control; *:P < 0.05 WT HIB versus WT CM;  n = 6–12/group; mean  ±  SEM). (f) Comparison of sarcomere-shortening amplitude at 4 Hz stimulation frequency of WT control cardiomyocytes and WT and TLR9-D cardiomyocytes incubated in HIB for 5–7 h  (n > 5; *:P < 0.05; mean  ±  SEM).
Mentions: To further validate the mRNA results of proinflammatory cytokines ELISAs of IL-1β and IL-6 were performed 18 h after CASP. Like the mRNA expression also the protein levels of the investigated cytokines in WT animals were significantly elevated after CASP surgery in WT mice (both versus WT Sham: IL-1β: P = 0.0221, Figure 5(a); IL-6: P = 0.0083, Figure 5(b)). In TLR9-D CASP mice protein concentrations of both proinflammatory cytokines stayed at the level of WT Sham hearts and were significantly lower than in WT CASP hearts (both versus WT CASP: IL-1β: P = 0.0281, Figure 5(a); IL-6: P = 0.0024, Figure 5(b)).

Bottom Line: CASP led to continuous release of bacteria into the peritoneal cavity, an increase of cytokines, and differential regulation of receptors of innate immunity in the heart.This coincided with reduced cardiomyocyte sarcomere shortening.TLR9 deficiency resulted in significant reduction of cardiac inflammation and a sustained heart function.

View Article: PubMed Central - PubMed

Affiliation: Institute for Physiology II, University of Bonn, Nussallee 11, 53115 Bonn, Germany.

ABSTRACT

Background: Aim was to elucidate the role of toll-like receptor 9 (TLR9) in cardiac inflammation and septic heart failure in a murine model of polymicrobial sepsis.

Methods: Sepsis was induced via colon ascendens stent peritonitis (CASP) in C57BL/6 wild-type (WT) and TLR9-deficient (TLR9-D) mice. Bacterial load in the peritoneal cavity and cardiac expression of inflammatory mediators were determined at 6, 12, 18, 24, and 36 h. Eighteen hours after CASP cardiac function was monitored in vivo. Sarcomere length of isolated cardiomyocytes was measured at 0.5 to 10 Hz after incubation with heat-inactivated bacteria.

Results: CASP led to continuous release of bacteria into the peritoneal cavity, an increase of cytokines, and differential regulation of receptors of innate immunity in the heart. Eighteen hours after CASP WT mice developed septic heart failure characterised by reduction of end-systolic pressure, stroke volume, cardiac output, and parameters of contractility. This coincided with reduced cardiomyocyte sarcomere shortening. TLR9 deficiency resulted in significant reduction of cardiac inflammation and a sustained heart function. This was consistent with reduced mortality in TLR9-D compared to WT mice.

Conclusions: In polymicrobial sepsis TLR9 signalling is pivotal to cardiac inflammation and septic heart failure.

Show MeSH
Related in: MedlinePlus