Cardiotrophin-1 (13. Cardiotrophin-1 and Endotoxin Burden)

Concerning the heart

The effect of CT-1 on serum and heart TNF levels in mice treated with lipopo lysaccharide (100 ng/mouse, iv) was studied. Co-treatment with CT-1 (5 micrograms/mouse intravenously) markedly inhibited TNF production both in serum and in the heart. The effect of CT-1 seems to be direct as it also inhibited TNF production when added to whole mouse blood cultured with lipopolysaccharide. Thus, CT-1 might play a protective role in some TNFmediated diseases ^Ref . CT-1 potentiates the elevation of serum corticosterone and IL-6 levels induced by IL-1 and induces the acute-phase protein serum amyloid a ^Ref . The effect of CT-1 on lipopolysaccharide (LPS)-induced cardiac dysfunction was examined in a rat model of sepsis. In the absence of CT-1, LPS (1 mg/kg ip) elicited a reduction of systolic function and dilation of the ventricular cavity within 3–6 h after administration. These physiological effects were accompanied by increased ventricular phosphorylation of signal transducers and activators of transcription (STAT) 1 and STAT3, activation of nuclear factor-kappaB and expression of iNOS mRNA. Notably, administration of CT-1 (20 microg/kg iv) immediately prior to LPS significantly inhibited all of these LPS-induced changes. To determine whether SOCS1 expression in cardiomyocytes is sufficient to inhibit LPS- and cytokine-induced expression of iNOS mRNA, the effects of forced expression of SOCS1 in cultured neonatal cardiomyocytes were investigated using an adenovirus-mediated transfection system. Forced expression of SOCS1 significantly inhibited iNOS transcription induced by LPS, tumor necrosis factor-alpha or interferon-gamma. The data suggest that CT-1-mediated expression of SOCS1 in cardiomyocytes may be a useful target for preventing sepsis-induced myocardial depression ^Ref .

Concerning the lung

The effects of CT-1 (100 microgram/kg ip, 10 min prior to endotoxin administration (ETX)) in a rat model of ETX-induced acute lung injury (Salmonella typhimurium lipopolysaccharide, 20 mg/kg ip) were studied. Six hours after ETX, lungs were harvested for determination of neutrophil accumulation (myeloperoxidase, MPO, assay) and lung edema (wet-to-dry weight ratio). Mechanisms of pulmonary vasorelaxation were examined in isolated pulmonary artery rings at 6 h by interrogating endothelium-dependent (response to acetylcholine) and endothelium-independent (response to sodium nitroprusside) relaxation following alpha-adrenergic (phenylephrine)-stimulated pre-constriction. CT-1 abrogated the endotoxin-induced lung neutrophil accumulation: 2.3 +/- 0.2 units MPO/g wet lung (gwl) vs 6. 3 +/- 0.3 units MPO/gwl in the ETX group (P < 0.05 vs ETX, P > 0.05 vs control). Similarly, CT-1 prevented ETX-induced lung edema: wet-to-dry-weight ratio, 4.473 +/- 0.039 vs 4.747 +/- 0.039 in the ETX group (P < 0.05 vs ETX, P > 0.05 vs control). Endotoxin caused significant impairment of both endothelium-dependent and -independent pulmonary vasorelaxation, and CT-1 attenuated this injury. Thus, cardiotrophin-1 possesses significant anti-inflammatory properties in a model of endotoxin-induced acute lung injury ^Ref .

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