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Toll-Like Receptor-Mediated Cardiac Injury during Experimental Sepsis.

ABSTRACT: Sepsis is associated with global cardiac dysfunction and with high mortality rate. The development of septic cardiomyopathy is due to complex interactions of damage-associated molecular patters, cytokines, and complement activation products. The aim of this study was to define the effects of sepsis on cardiac structure, gap junction, and tight junction (TJ) proteins. Sepsis was induced by cecal ligation and puncture in male C57BL/6 mice. After a period of 24?h, the expression of cardiac structure, gap junction, and TJ proteins was determined. Murine HL-1 cells were stimulated with LPS, and mRNA expression of cardiac structure and gap junction proteins, intracellular reactive oxygen species, and troponin I release was analyzed. Furthermore, pyrogenic receptor subtype 7 (P2X7) expression and troponin I release of human cardiomyocytes (iPS) were determined after LPS exposure. In vivo, protein expression of connexin43 and ?-actinin was decreased after the onset of polymicrobial sepsis, whereas in HL-1 cells, mRNA expression of connexin43, ?-actinin, and desmin was increased in the presence of LPS. Expression of TJ proteins was not affected in vivo during sepsis. Although the presence of LPS and nigericin resulted in a significant troponin I release from HL-1 cells. Sepsis affected cardiac structure and gap junction proteins in mice, potentially contributing to compromised cardiac function.

SUBMITTER: Lackner I

PROVIDER: S-EPMC7199613 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature

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Toll-Like Receptor-Mediated Cardiac Injury during Experimental Sepsis.

Lackner Ina I Weber Birte B Chakraborty Shinjini S Braumüller Sonja S Huber-Lang Markus M Gebhard Florian F Kalbitz Miriam M

Mediators of inflammation 20200110

Sepsis is associated with global cardiac dysfunction and with high mortality rate. The development of septic cardiomyopathy is due to complex interactions of damage-associated molecular patters, cytokines, and complement activation products. The aim of this study was to define the effects of sepsis on cardiac structure, gap junction, and tight junction (TJ) proteins. Sepsis was induced by cecal ligation and puncture in male C57BL/6 mice. After a period of 24 h, the expression of cardiac structur ...[more]

PMID: 32410859

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Project description:Peroxisome proliferator-activated receptor-? is significantly down-regulated in circulating leukocytes from children with sepsis. Peroxisome proliferator-activated receptor-? null (Ppara) mice have greater mortality than wild-type mice when subjected to sepsis by cecal ligation and puncture. We sought to characterize the role of peroxisome proliferator-activated receptor-? in sepsis and to identify the mechanism whereby peroxisome proliferator-activated receptor-? confers a survival advantage.Prospective randomized preclinical study.Laboratory investigation.Male C57Bl/6J and Ppara mice (B6.129S4-Ppara/J), aged 12-16 weeks.Bone marrow chimeric mice were generated and subjected to cecal ligation and puncture. Survival was measured for 7 days. Separate groups of nontransplanted mice underwent cecal ligation and puncture and were euthanized 24 hours later for plasma and tissue analyses.Ppara mice had dramatically reduced survival compared with wild-type mice irrespective of the peroxisome proliferator-activated receptor-? status of the bone marrow they received (3% vs 63%; p < 0.0001). No difference in survival was observed between Ppara mice that received wild-type versus Ppara marrow or in wild-type mice receiving wild-type versus Ppara marrow. In septic, nontransplanted mice at 24 hours, Ppara mice had elevated cardiac troponin levels compared with wild-type mice. Cardiac histologic injury scores were greater in Ppara versus wild-type mice. Expression of transcription factors and enzymes related to fatty acid oxidation in the heart were profoundly down-regulated in both wild-type and Ppara mice, but more so in the Ppara mice.Peroxisome proliferator-activated receptor-? expression in nonhematopoietic tissues plays a critical role in determining clinical outcome in experimental polymicrobial sepsis and is more important to survival in sepsis than hematopoietic peroxisome proliferator-activated receptor-? expression. Cardiac injury due to inadequate energy production from fatty acid substrate is a probable mechanism of decreased survival in Ppara mice. These results suggest that altered peroxisome proliferator-activated receptor-?-mediated cellular metabolism may play an important role in sepsis-related end-organ injury and dysfunction, especially in the heart.

Project description:WHAT WE ALREADY KNOW ABOUT THIS TOPIC:Toll-like receptor 7 responds to elevated single-stranded RNA by increasing cytokine production. Sepsis is characterized by elevated plasma levels of tissue damage (and pathogen)-associated molecular patterns, including RNA. WHAT THIS ARTICLE TELLS US THAT IS NEW:Using murine models of bacterial sepsis, knockout of the Toll-like receptor 7 resulted in lower mortality and cytokine levels and less end-organ injury. Therefore, Toll-like receptor 7, which mediates innate immune response, contributes to harm in experimental sepsis. BACKGROUND:Sepsis remains a critical illness with high mortality. The authors have recently reported that mouse plasma RNA concentrations are markedly increased during sepsis and closely associated with its severity. Toll-like receptor 7, originally identified as the sensor for single-stranded RNA virus, also mediates host extracellular RNA-induced innate immune responses in vitro and in vivo. Here, the authors hypothesize that innate immune signaling via Toll-like receptor 7 contributes to inflammatory response, organ injury, and mortality during polymicrobial sepsis. METHODS:Sepsis was created by (1) cecal ligation and puncture or (2) stool slurry peritoneal injection. Wild-type and Toll-like receptor 7 knockout mice, both in C57BL/6J background, were used. The following endpoints were measured: mortality, acute kidney injury biomarkers, plasma and peritoneal cytokines, blood bacterial loading, peritoneal leukocyte counts, and neutrophil phagocytic function. RESULTS:The 11-day overall mortality was 81% in wild-type mice and 48% in Toll-like receptor 7 knockout mice after cecal ligation and puncture (N = 27 per group, P = 0.0031). Compared with wild-type septic mice, Toll-like receptor 7 knockout septic mice also had lower sepsis severity, attenuated plasma cytokine storm (wild-type vs. Toll-like receptor 7 knockout, interleukin-6: 43.2 [24.5, 162.7] vs. 4.4 [3.1, 12.0] ng/ml, P = 0.003) and peritoneal inflammation, alleviated acute kidney injury (wild-type vs. Toll-like receptor 7 knockout, neutrophil gelatinase-associated lipocalin: 307 ± 184 vs.139 ± 41-fold, P = 0.0364; kidney injury molecule-1: 40 [16, 49] vs.13 [4, 223]-fold, P = 0.0704), lower bacterial loading, and enhanced leukocyte peritoneal recruitment and phagocytic activities at 24?h. Moreover, stool slurry from wild-type and Toll-like receptor 7 knockout mice resulted in similar level of sepsis severity, peritoneal cytokines, and leukocyte recruitment in wild-type animals after peritoneal injection. CONCLUSIONS:Toll-like receptor 7 plays an important role in the pathogenesis of polymicrobial sepsis by mediating host innate immune responses and contributes to acute kidney injury and mortality.

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Toll-Like Receptor-Mediated Cardiac Injury during Experimental Sepsis.

Publications

Toll-Like Receptor-Mediated Cardiac Injury during Experimental Sepsis.

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