Increased P-selectin gene expression in the liver vasculature and its role in the pathophysiology of neutrophil-induced liver injury in murine endotoxin shock.

We studied the role of P-selectin, an adhesion molecule known to be important for neutrophil localization to sites of inflammation, in a model of inflammatory liver injury. Male C3Heb/FeJ (ET-sensitive) mice treated with 700 mg/kg galactosamine and 100 microg/kg Salmonella abortus equi endotoxin (Gal/ET), murine tumor necrosis factor alpha (TNF-alpha, 15 microg/kg), or interleukin-1 (IL-1, 13-23 microg/kg), showed increased P-selectin mRNA levels in the liver. In contrast, C3H/HeJ (ET-resistant) mice responded only to cytokines with P-selectin mRNA formation. Whereas no P-selectin expression was detectable in control livers, there was temporary staining of endothelium in large blood vessels but not in sinusoids between 3 and 5 h after ET, TNF-alpha, or IL-1 treatment. Severe liver injury induced by Gal/ET at 7 h was not inhibited by an anti-P-selectin antibody in C3Heb/FeJ mice or in P-selectin-deficient animals. Sequestration of neutrophils in sinusoids, i.e. those neutrophils that have been identified as critical for the injury, was not affected by the antibody or in P-selectin-deficient mice. However, the temporary margination in portal and post-sinusoidal venules was reduced by 75% in anti-P-selectin antibody-treated animals and by 51% in P-selectin-deficient mice. We conclude that hepatic P-selectin gene transcription in vivo involves cytokines. However, blocking P-selectin neither attenuated sinusoidal neutrophil sequestration nor prevented neutrophil-induced liver injury during endotoxin shock but attenuated neutrophil margination in larger vessels. Thus, our data demonstrate similarities and fundamental differences in the requirement for adhesion molecules to localize neutrophils in the liver vasculature compared to other organs during an inflammatory response.

Transcriptional activation of vascular cell adhesion molecule-1 gene in vivo and its role in the pathophysiology of neutrophil-induced liver injury in murine endotoxin shock.

Polymorphonuclear leukocytes (neutrophils) can cause hepatic parenchymal cell injury during endotoxin (ET) shock. Because adhesion molecules are critical for inflammatory cell damage, the role of vascular cell adhesion molecule-1 (VCAM-1) was studied in the pathophysiology of ET shock. ET-sensitive mice (C3Heb/FeJ) were treated with 700 mg/kg galactosamine in combination with 100 microg/kg Salmonella abortus equi ET, 15 microg/kg TNF-alpha, or 13 to 23 microg/kg IL-1. VCAM-1 mRNA formation was strongly activated in animals treated with ET, TNF-alpha, or IL-1. In contrast, only TNF-alpha and IL-1, not ET, induced VCAM-1 gene transcription in livers of ET-resistant mice (C3H/HeJ). Immunohistochemistry and isolation of liver cells during endotoxemia indicated that VCAM-1 mRNA and protein were only formed in endothelial cells and Kupffer cells, not in hepatocytes. Galactosamine/ET induced neutrophil accumulation in sinusoids (515 +/- 30 neutrophils/50 high power fields) followed by transmigration at 7 h. At that time, severe liver injury was observed (necrosis, 53 +/- 5%). An anti-VCAM-1 Ab (3 mg/kg) attenuated the area of necrosis by 60%. The Ab reduced neutrophil transmigration by 84%, but had no effect on the total number of cells in the liver vasculature. Flow cytometric analysis identified the presence of very late Ag-4 on mouse peripheral neutrophils. Our data demonstrated cytokine-dependent VCAM-1 gene transcription and protein expression in the liver during endotoxemia. Neutrophils were able to use very late Ag-4/VCAM-1 interactions to transmigrate into liver parenchyma in vivo. Preventing transmigration by blocking VCAM-1 protected hepatocytes against neutrophil-induced injury.

Neutrophil margination and extravasation in sinusoids and venules of liver during endotoxin-induced injury.

Neutrophils contribute to liver damage during endotoxin shock. The objective of this investigation was to document where neutrophils localize in the hepatic vasculature and whether they migrate out of sinusoids or postsinusoidal venules. A well-characterized model of galactosamine and endotoxin shock and immunostaining for neutrophil-associated migration inhibition factor-related protein complex 8/14 S100 calcium-binding proteins were used. Treatment of C3Heb/FeJ mice with 100 micrograms/kg Salmonella abortus equi endotoxin alone or in combination with 700 mg/kg galactosamine induced a time-dependent increase of neutrophil margination in sinusoids and postsinusoidal venules at 4 h. The number of venular neutrophils decreased in both groups at later time points without evidence for transmigration. Extravasation of neutrophils was only observed from sinusoids in galactosamine plus endotoxin-treated animals between 4 and 7 h, which correlated with parenchymal cell injury. After endotoxin alone, large numbers of neutrophils remained sequestered in sinusoids without injury. These data suggest that neutrophils cause hepatocellular injury during endotoxemia after extravasation and are less likely to cause damage when sequestered in the vasculature. In the liver, neutrophils migrate out of sinusoids and not out of postsinusoidal venules.

Inhibition of NF-kappa B activation by dimethyl sulfoxide correlates with suppression of TNF-alpha formation, reduced ICAM-1 gene transcription, and protection against endotoxin-induced liver injury.

The effect of the free radical scavenger dimethyl sulfoxide (DMSO) on activation of the nuclear transcription factor kappa B (NF-kappa B) was investigated in an experimental model of endotoxin-induced liver failure. In galactosamine-sensitized C3Heb/FeJ mice, DMSO (10 mL/kg) effectively inhibited endotoxin-induced hepatic NF-kappa B activation, suppressed TNF-alpha levels in plasma by 86%, attenuated intercellular adhesion molecule-1 (ICAM-1) mRNA formation, blocked hepatic neutrophil accumulation by 79%, and reduced liver injury by 80%. In galactosamine-sensitized mice treated with 20 micrograms/kg murine TNF-alpha, DMSO moderately reduced hepatic NF-kappa B and decreased ICAM-1 mRNA formation and liver injury by 83%, but had no significant effect on hepatic neutrophil accumulation. Thus, DMSO was able to inhibit, at least in part, two critical NF-kappa B-dependent steps in the pathophysiology, i.e., TNF-alpha formation and ICAM-1 gene transcription. Our data suggest the involvement of redox-sensitive events in the signal transduction pathway of NF-kappa B activation in the liver. Inhibition of NF-kappa B activation correlates with the reduced activation of proinflammatory genes in vivo and the subsequent attenuation of inflammatory liver injury. Thus, antioxidants that are NF-kappa B inhibitors may have therapeutic potential in endotoxin shock and sepsis.

Endotoxin-induced activation of the nuclear transcription factor kappa B and expression of E-selectin messenger RNA in hepatocytes, Kupffer cells, and endothelial cells in vivo.

Endotoxin causes neutrophil sequestration in the liver and severe vascular and parenchymal cell injury. Inducible adhesion molecules such as intercellular adhesion molecule-1 and selectins are involved in neutrophil recruitment to an inflammatory site in vivo. The objective of our study was to characterize the translocation of the nuclear factor kappa B (NF-kappa B) from the cytoplasm to the nucleus (NF-kappa B activation) during endotoxemia using the electrophoretic mobility shift assay and to investigate its role in regulation of E-selectin gene transcription in liver cells in vivo. Administration of 0.5 mg/kg Salmonella enteritidis endotoxin to male Fischer rats induced a drastic but transient activation of NF-kappa B at the whole liver level. Major subunits identified were p50 (NF-kappa B1), p65 (RelA), and c-Rel, but not p52 (NF-kappa B2). Isolation of liver cells from control animals induced substantial NF-kappa B activation in Kupffer cells and endothelial cells and minor activation in hepatocytes. One hour after endotoxin treatment in vivo, NF-kappa B was uniformly activated in all isolated cells. At 5 h, NF-kappa B activation was reduced to various degrees in all cell types, with hepatocytes showing only a moderate decrease. Northern blot analysis indicated no E-selectin mRNA in all control cells; however, at 1 h, endotoxin induced E-selectin gene transcription transiently in endothelial cells and in Kupffer cells but not in hepatocytes. These data support the hypothesis that NF-kappa B activation is important for E-selectin gene transcription in hepatic vascular lining cells. However, the fact that hepatic parenchymal cells, despite NF-kappa B activation do not express E- selectin mRNA, suggests that NF-kappa B activation alone is not sufficient for E-selectin gene transcription in vivo.

Release of soluble intercellular adhesion molecule 1 into bile and serum in murine endotoxin shock.

Neutrophil-induced liver injury during endotoxemia is dependent on the adhesion molecules Mac-1 (CD11b/CD18) on neutrophils and its counterreceptor on endothelial cells and hepatocytes, intercellular adhesion molecule 1 (ICAM-1). To investigate a potential release of a soluble form of ICAM-1 (sICAM-1), animals received 100 micrograms/kg Salmonella abortus equi endotoxin alone or in combination with 700 mg/kg galactosamine. In endotoxin-sensitive mice (C3Heb/FeJ), injection of endotoxin did not cause liver injury but induced a time-dependent increase of sICAM-1 in serum (300%) and in bile (615%) without affecting bile flow. In galactosamine/endotoxin-treated animals, which developed liver injury, the increase in both compartments was only 97% and 104%, respectively. In either case, the increase in sICAM-1 concentrations paralleled the enhanced ICAM-1 expression in the liver. The endotoxin-resistant strain (C3H/HeJ) did not show elevated sICAM-1 levels in serum or bile after endotoxin administration. In contrast, the intravenous injection of murine tumor necrosis factor alpha (TNF-alpha), interleukin-1 alpha (IL-1 alpha) or IL-1 beta (13-23 micrograms/kg) into endotoxin-resistant mice induced a 225% to 364% increase in serum sICAM-1 and a 370% elevation of the biliary efflux of sICAM-1, again independent of changes in bile flow. These data indicate that cytokines are major inducers of sICAM-1 formation during endotoxemia in vivo. The described experimental model can be used to investigate the role of sICAM-1 in the pathophysiology of inflammatory liver disease.

Cytokine-induced upregulation of hepatic intercellular adhesion molecule-1 messenger RNA expression and its role in the pathophysiology of murine endotoxin shock and acute liver failure.

Neutrophil-induced liver injury during endotoxemia is dependent on the adhesion molecule Mac-1 (CD11b/CD18) on neutrophils. The potential involvement of its counterreceptor, intercellular adhesion molecule-1 (ICAM-1), in the pathogenesis was investigated after administration of 100 micrograms/kg Salmonella abortus equi endotoxin (ET) in galactosamine-sensitized mice (Gal). In ET-sensitive mice (C3Heb/FeJ), which generated large amounts of tumor necrosis factor-alpha (TNF-alpha), massive neutrophil infiltration and severe liver injury were observed. In an ET-resistant strain (C3H/HeJ), which did not generate TNF-alpha Gal/ET failed to cause neutrophil accumulation or injury. ICAM-1 messenger RNA (mRNA), negligible in control livers, was selectively induced by Gal/ET in ET-sensitive mice. Intravenous injection of murine TNF-alpha, interleukin-1 alpha (IL-1 alpha) or IL-I beta (13 to 23 micrograms/kg) strongly induced the ICAM-1 message in both strains, showing a comparable capacity for ICAM-1 mRNA synthesis. All cytokines caused similar neutrophil accumulation in the liver; however, only Gal/TNF-alpha also caused upregulation of Mac-1 on circulating neutrophils and liver injury. The anti-murine ICAM-1 monoclonal antibody YN.1 (3 mg/kg) attenuated liver injury in ET-sensitive mice by 67% to 90% compared with isotype-matched control antibody-treated animals but did not reduce neutrophil accumulation in hepatic sinusoids. Our data suggest that the cytokines TNF-alpha and IL-1 are the main mediators responsible for upregulation of ICAM-1 mRNA in the liver during endotoxemia. The upregulation of both adhesion molecules, ICAM-1 and Mac-1, is necessary for a neutrophil-induced liver injury to occur. (ABSTRACT TRUNCATED AT 250 WORDS)

Differential induction of mRNA for ICAM-1 and selectins in hepatocytes, Kupffer cells and endothelial cells during endotoxemia.

Intercellular adhesion molecule-1 (ICAM-1) and selectins (E- and P-selectin) mRNAs were determined in individual liver cell types by Northern blot analysis before and after injection of endotoxin. A constitutive expression of ICAM-1 mRNA was found in endothelial cells and Kupffer cells but not in hepatocytes. All three cell types showed upregulation of ICAM-1 mRNA after endotoxin. No constitutive selectin expression could be detected in any liver cell, but endotoxin induced massive synthesis of E- and P-selectin mRNA in endothelial cells and Kupffer cells. The differential expression of cellular adhesion molecules in the liver is consistent with the involvement of selectins in neutrophil rolling in the vasculature and ICAM-1 in transendothelial migration and adherence to parenchymal cells.

Demonstration of novel anti-arthritic and anti-inflammatory effects of diphosphonates.

Diphosphonates (DP) are synthetic pyrophosphates with a P-C-P backbone and are predominantly used for the treatment of bone diseases. Several DP have also been shown to exert significant antiarthritic effects in the rat adjuvant-induced polyarthritis model; however, there is no direct evidence for the anti-inflammatory effects of these compounds. We therefore tested the effects of dichloromethylene diphosphonate on delayed-type hypersensitivity granuloma elicited by s.c. implantation of antigen-soaked hydroxyapatite disks in antigen-sensitized mice. Dichloromethylene diphosphonate induced a dose-related inhibition of the delayed-type hypersensitivity granuloma response (38-64% at 25-100 mg/kg/day s.c. or p.o.); novel DP analogs, U-81581, U-82579 and U-84849 were also effective in the same dose range. In contrast, all DP failed to suppress 24-hr delayed-type hypersensitivity paw edema in mice. In addition to rat adjuvant-induced polyarthritis, mouse antigen-induced erosive arthritis was also significantly suppressed by s.c. administration of all four DP. Toxicity was minimal for each DP (> 600 mg/kg p.o. or s.c.). We conclude that DP represent a novel class of anti-inflammatory agents with excellent therapeutic potential for chronic inflammatory diseases including rheumatoid arthritis.

Role of interferon-gamma in the modulation of the IgE response by 2,4-dinitrophenyl-Bordetella pertussis vaccine in the mouse.

Immunization of mice with 2,4-dinitrophenyl-Bordetella pertussis (DNP-BP) failed to induce anti-DNP IgE responses. Administration of DNP-BP induced, however, the formation of anti-DNP IgE B memory cells, as demonstrated by adoptive transfer. Furthermore, mice pretreated with DNP-BP and primed with 2 micrograms DNP-ovalbumin (OA) in alum 2 weeks later produced high day-7 anti-DNP IgE levels. These subsided to near undetectable levels by day 12-14. The transient expression of serum IgE levels was accompanied by normal levels of anti-DNP IgG. The anti-OA response induced as a result of priming with DNP-OA in alum was not affected by pretreatment with DNP-BP. IgG subclass analysis revealed that mice pretreated with DNP-BP had elevated levels of IgG2a and reduced levels of IgG1 as compared to control (TNP-keyhole limpet hemocyanin-pretreated) mice. Treatment of mice with an anti-interferon-gamma monoclonal antibody, shortly after immunization with DNP-BP, not only reduced anti-DNP IgG2a levels, but prevented the sharp anti-DNP IgE decline that occurred after priming with DNP-OA in alum. These results suggest that DNP-BP-induced interferon-gamma production modulates Ig isotype expression in vivo in an anti-gen-specific manner.