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Lipopolysaccharide induces disseminated endothelial apoptosis requiring ceramide generation.

Haimovitz-Friedman A, Cordon-Cardo C, Bayoumy S, Garzotto M, McLoughlin M, Gallily R, Edwards CK, Schuchman EH, Fuks Z, Kolesnick R - J. Exp. Med. (1997)

Bottom Line: TNF-binding protein, which protects against LPS-induced death, blocked LPS-induced ceramide generation and endothelial apoptosis, suggesting systemic TNF is required for both responses.Furthermore, intravenous injection of basic fibroblast growth factor, which acts as an intravascular survival factor for endothelial cells, blocked LPS-induced ceramide elevation, endothelial apoptosis and animal death, but did not affect LPS-induced elevation of serum TNF-alpha.These investigations demonstrate that LPS induces a disseminated form of endothelial apoptosis, mediated sequentially by TNF and ceramide generation, and suggest that this cascade is mandatory for evolution of the endotoxic syndrome.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York 10021, USA.

ABSTRACT
The endotoxic shock syndrome is characterized by systemic inflammation, multiple organ damage, circulatory collapse and death. Systemic release of tumor necrosis factor (TNF)-alpha and other cytokines purportedly mediates this process. However, the primary tissue target remains unidentified. The present studies provide evidence that endotoxic shock results from disseminated endothelial apoptosis. Injection of lipopolysaccharide (LPS), and its putative effector TNF-alpha, into C57BL/6 mice induced apoptosis in endothelium of intestine, lung, fat and thymus after 6 h, preceding nonendothelial tissue damage. LPS or TNF-alpha injection was followed within 1 h by tissue generation of the pro-apoptotic lipid ceramide. TNF-binding protein, which protects against LPS-induced death, blocked LPS-induced ceramide generation and endothelial apoptosis, suggesting systemic TNF is required for both responses. Acid sphingomyelinase knockout mice displayed a normal increase in serum TNF-alpha in response to LPS, yet were protected against endothelial apoptosis and animal death, defining a role for ceramide in mediating the endotoxic response. Furthermore, intravenous injection of basic fibroblast growth factor, which acts as an intravascular survival factor for endothelial cells, blocked LPS-induced ceramide elevation, endothelial apoptosis and animal death, but did not affect LPS-induced elevation of serum TNF-alpha. These investigations demonstrate that LPS induces a disseminated form of endothelial apoptosis, mediated sequentially by TNF and ceramide generation, and suggest that this cascade is mandatory for evolution of the endotoxic syndrome.

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TNF-α induces ceramide generation in intestinal mucosa.  (A) Time course of the effect of 25 μg of recombinant human TNF-α/ 25g mouse; (B) dose response at 2 h. These studies were performed as in  Fig. 2 except C57BL/6 mice were injected with TNF-α retro-orbitally.  The data (mean ± SEM) represent triplicate determinations from two  mice per point from one representative of three experiments for A and  one representative of four experiments for B.
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Figure 3: TNF-α induces ceramide generation in intestinal mucosa. (A) Time course of the effect of 25 μg of recombinant human TNF-α/ 25g mouse; (B) dose response at 2 h. These studies were performed as in Fig. 2 except C57BL/6 mice were injected with TNF-α retro-orbitally. The data (mean ± SEM) represent triplicate determinations from two mice per point from one representative of three experiments for A and one representative of four experiments for B.

Mentions: Since TNF-α is a primary mediator of the septic shock response to LPS (4–6), and since ceramide has been described as a mediator of TNF-induced apoptosis in numerous cellular systems (17–19), we investigated the effect of TNF-α on tissue ceramide generation, endothelial apoptosis, and survival of C57BL/6 mice. Recombinant human TNF-α, when injected intravenously, induced time- and dose-dependent lethality in this strain of mice. As little as 5 μg of TNF-α/25g mouse was effective and the LD50, although somewhat variable between experiments, ranged from 25–50 μg of TNF-α/25g mouse. At a dose of 25 μg of TNF-α/25g mouse, death occurred as early as 10 h after injection and the mean time until death in multiple experiments was 24 h (data not shown). Fig. 3 A shows that TNF-α induced time- and dose-dependent ceramide generation in the intestinal mucosa. 25 μg of TNF-α/25g mouse stimulated an increase in ceramide content with a slightly more rapid time course than induced by LPS. TNF-α–induced ceramide generation was detected by 0.5 h and peaked at 1.5 h (P <0.001 vs. control). As little as 2.5 μg of TNF-α/25g mouse was effective and a maximal effect occurred with 25 μg of TNF-α/25g mouse (Fig. 3 B). TNF-α, like LPS, induced endothelial apoptosis in intestinal mucosa, lung, and fat tissues, beginning 6 h after injection (data not shown). These studies demonstrate that TNF-α, like LPS, induces tissue ceramide generation followed by microvascular endothelial apoptosis and demise of the animal.


Lipopolysaccharide induces disseminated endothelial apoptosis requiring ceramide generation.

Haimovitz-Friedman A, Cordon-Cardo C, Bayoumy S, Garzotto M, McLoughlin M, Gallily R, Edwards CK, Schuchman EH, Fuks Z, Kolesnick R - J. Exp. Med. (1997)

TNF-α induces ceramide generation in intestinal mucosa.  (A) Time course of the effect of 25 μg of recombinant human TNF-α/ 25g mouse; (B) dose response at 2 h. These studies were performed as in  Fig. 2 except C57BL/6 mice were injected with TNF-α retro-orbitally.  The data (mean ± SEM) represent triplicate determinations from two  mice per point from one representative of three experiments for A and  one representative of four experiments for B.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2199151&req=5

Figure 3: TNF-α induces ceramide generation in intestinal mucosa. (A) Time course of the effect of 25 μg of recombinant human TNF-α/ 25g mouse; (B) dose response at 2 h. These studies were performed as in Fig. 2 except C57BL/6 mice were injected with TNF-α retro-orbitally. The data (mean ± SEM) represent triplicate determinations from two mice per point from one representative of three experiments for A and one representative of four experiments for B.
Mentions: Since TNF-α is a primary mediator of the septic shock response to LPS (4–6), and since ceramide has been described as a mediator of TNF-induced apoptosis in numerous cellular systems (17–19), we investigated the effect of TNF-α on tissue ceramide generation, endothelial apoptosis, and survival of C57BL/6 mice. Recombinant human TNF-α, when injected intravenously, induced time- and dose-dependent lethality in this strain of mice. As little as 5 μg of TNF-α/25g mouse was effective and the LD50, although somewhat variable between experiments, ranged from 25–50 μg of TNF-α/25g mouse. At a dose of 25 μg of TNF-α/25g mouse, death occurred as early as 10 h after injection and the mean time until death in multiple experiments was 24 h (data not shown). Fig. 3 A shows that TNF-α induced time- and dose-dependent ceramide generation in the intestinal mucosa. 25 μg of TNF-α/25g mouse stimulated an increase in ceramide content with a slightly more rapid time course than induced by LPS. TNF-α–induced ceramide generation was detected by 0.5 h and peaked at 1.5 h (P <0.001 vs. control). As little as 2.5 μg of TNF-α/25g mouse was effective and a maximal effect occurred with 25 μg of TNF-α/25g mouse (Fig. 3 B). TNF-α, like LPS, induced endothelial apoptosis in intestinal mucosa, lung, and fat tissues, beginning 6 h after injection (data not shown). These studies demonstrate that TNF-α, like LPS, induces tissue ceramide generation followed by microvascular endothelial apoptosis and demise of the animal.

Bottom Line: TNF-binding protein, which protects against LPS-induced death, blocked LPS-induced ceramide generation and endothelial apoptosis, suggesting systemic TNF is required for both responses.Furthermore, intravenous injection of basic fibroblast growth factor, which acts as an intravascular survival factor for endothelial cells, blocked LPS-induced ceramide elevation, endothelial apoptosis and animal death, but did not affect LPS-induced elevation of serum TNF-alpha.These investigations demonstrate that LPS induces a disseminated form of endothelial apoptosis, mediated sequentially by TNF and ceramide generation, and suggest that this cascade is mandatory for evolution of the endotoxic syndrome.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York 10021, USA.

ABSTRACT
The endotoxic shock syndrome is characterized by systemic inflammation, multiple organ damage, circulatory collapse and death. Systemic release of tumor necrosis factor (TNF)-alpha and other cytokines purportedly mediates this process. However, the primary tissue target remains unidentified. The present studies provide evidence that endotoxic shock results from disseminated endothelial apoptosis. Injection of lipopolysaccharide (LPS), and its putative effector TNF-alpha, into C57BL/6 mice induced apoptosis in endothelium of intestine, lung, fat and thymus after 6 h, preceding nonendothelial tissue damage. LPS or TNF-alpha injection was followed within 1 h by tissue generation of the pro-apoptotic lipid ceramide. TNF-binding protein, which protects against LPS-induced death, blocked LPS-induced ceramide generation and endothelial apoptosis, suggesting systemic TNF is required for both responses. Acid sphingomyelinase knockout mice displayed a normal increase in serum TNF-alpha in response to LPS, yet were protected against endothelial apoptosis and animal death, defining a role for ceramide in mediating the endotoxic response. Furthermore, intravenous injection of basic fibroblast growth factor, which acts as an intravascular survival factor for endothelial cells, blocked LPS-induced ceramide elevation, endothelial apoptosis and animal death, but did not affect LPS-induced elevation of serum TNF-alpha. These investigations demonstrate that LPS induces a disseminated form of endothelial apoptosis, mediated sequentially by TNF and ceramide generation, and suggest that this cascade is mandatory for evolution of the endotoxic syndrome.

Show MeSH
Related in: MedlinePlus