Tumor necrosis factor-alpha gene and protein expression in adult feline myocardium after endotoxin administration.

Abstract

TNFa mRNA and protein biosynthesis were examined in the adult feline heart after stimulation with endotoxin. When freshly isolated hearts were stimulated with endotoxin in vitro, de novo TNFa mRNA expression occurred within 30 min, and TNFa protein production was detected within 60-75 min; however, TNFa mRNA and protein production were not detected in diluent-treated hearts. Immunohistochemical studies localized TNFa to endothelial cells, smooth muscle cells, and cardiac myocytes in the endotoxin-treated hearts, whereas TNFa immunostaining was absent in the diluent-treated hearts. To determine whether the cardiac myocyte was a source for TNFa production, two studies were performed. First, in situ hybridization studies, using highly specific biotinylated probes, demonstrated TNFa mRNA in cardiac myocytes from endotoxin-stimulated hearts; in contrast, TNFa mRNA was not expressed in myocytes from diluent-treated hearts. Second, TNFa protein production was observed when cultured cardiac myocytes were stimulated with endotoxin, whereas TNFa protein production was not detected in the diluent-treated cells. The functional significance of the intramyocardial production of TNFa was determined by examining cell motion in isolated cardiac myocytes treated with superfusates from endotoxinand diluent-stimulated hearts. These studies showed that cell motion was depressed in myocytes treated with superfusates from the endotoxin-treated hearts, but was normal with the superfusates from the diluent-treated hearts; moreover, the negative inotropic effects of the superfusates from the endotoxin-treated hearts could be abrogated completely by pretreatment with an anti-TNFa antibody. Finally, endotoxin stimulation was also shown to result in the intramyocardial production of TNFa mRNA and protein in vivo.Thus, this study shows for the first time that the adult mammalian myocardium synthesizes biologically active TNFa. (J. Clin. Invest. 1995. 96:1042-1052

Sphingosine Mediates the Immediate Negative Inotropic Effects of Tumor Necrosis Factor-α in the Adult Mammalian Cardiac Myocyte

“…2 shows two important findings with respect to group data for sphingosine levels in isolated cardiac myocytes. First, stimulating the cells with a concentration of TNF-␣ (200 units⅐ml Ϫ1 ) that consistently depresses cell shortening (6,32) resulted in a significant (p Ͻ 0.05) increase in free sphingosine levels within 30 min, whereas stimulating the cells with a concentration of TNF-␣ (20 units⅐ml Ϫ1 ) that does not depress cell shortening (6) did not stimulate increased (p Ͼ 0.05) levels of free sphingosine levels relative to control values. Moreover, the time course for the TNF-␣-stimulated increase in sphingosine levels was sufficiently rapid to explain the temporal development (i.e.…”

“…The specificity of the mutated TNF ligands for binding to feline TNFR1 and TNFR2 has been validated previously (18). For these studies we used a single concentration of TNFM1(2 ng⅐ml Ϫ1 ) and TNFM2 (2 ng⅐ml Ϫ1 ), since this concentration is equivalent to the concentration of wild-type TNF-␣ (200 units⅐ml Ϫ1 ) that produces welldefined negative inotropic effects in adult feline cardiac myocytes (6) Isolated Cell Mechanics-Cell motion was characterized by videoedge detection at a stimulation frequency of 0.25 Hz, using experimental conditions identical to those we have described elsewhere (6,32). Four separate series of experiments were performed.…”

CXCR4 modulates contractility in adult cardiac myocytes

“…The hypothesis that inflammation plays a role in cardiac dysfunction was first suggested from animal [23] and human studies of sepsis (reviewed by van der Poll et al [24]). Sepsis-associated cardiac dysfunction was thought to be mediated, in part, by circulating or "humoral" myocardial depressants that were subsequently identified as predominantly inflammatory cytokines (including tumor necrosis factor-1alpha (TNF-1α), interleukin-1beta, (IL-1β) [25], IL-6 [26], IL-2 [27] and interferon-gamma (IFN-γ)).…”

Excessive Tumor Necrosis Factor Activation After Infarction Contributes to Susceptibility of Myocardial Rupture and Left Ventricular Dysfunction

“…1 Chronically after MI, heart failure has an escalating cardiovascular burden worldwide, and the 1-year mortality remains high at 25% to 40%. 2 Accumulated evidence indicates that cytokines are important mediators of wound healing and remodeling after MI. They are elaborated by immune, vascular, and interstitial tissues to regulate important biological processes of cell growth, migration, repair, and fibrosis.…”