ISSN:1073-2322    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Interleukin-10 (IL-10) protects animals from lethal endotoxemia. This beneficial effect is mediated, in part, by inhibition of inflammatory cytokine production, including tumor necrosis factor-α (TNF-α). Evidence suggests that IL-10 may inhibit activation of the transcription factor nuclear factor-kB (NF-kB) through an unknown mechanism. NF-kB activation in response to inflammatory signals is dependent upon degradation of its associated inhibitory peptide, inhibitorykB-α (IkB-α). We hypothesized that IL-10 prevents human monocyte NF-kB activation and resultant TNF-α production by stabilization of IkB-α. The purpose of this study was to determine the effect of IL-10 on lipopolysaccharide (LPS)-induced human monocyte TNF-α production, NF-kB activation, and IkB-α degradation. Monocytes were isolated from human donors. Cells were stimulated with endotoxin (LPS, 100 ng/mL) with and without human IL-10 (10 ng/mL). Following stimulation, TNF-α was measured in cell supernatants by ELISA, NF-kB activity by electrophoretic mobility shift assay, and IkB-α levels by Western blot. We observed that after LPS stimulation of human monocytes, TNF-α increased to 798 ± 67 pg/mL (p < .001 versus control). IL-10 attenuated LPS-stimulated TNF-α production (297 ± 54;pkB-α protein levels decreased, and NF-kB DNA binding increased. IL-10 pretreatment prevented LPS-induced decreases in IkB-α protein levels and attenuated NF-kB DNA binding. IL-10 appears to prevent activation of NF-kB by preserving IkB-α protein levels, leading to a reduction in TNF-α release.

ISSN:1073-2322    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Experimental models of lethal endotoxemia in rodents are widely used to delineate pathogenic mechanisms of inflammation, sepsis, and septic shock. One long-standing but poorly understood observation is that removal of the pituitary gland (hypophysectomy) renders experimental animals 1,000-fold more sensitive to the lethal sequelae of lipopolysaccharide (LPS). Previous explanations for this phenomenon focused on hypophysectomy-induced deficiencies of corticosteroids, because glucocorticoids effectively suppress the synthesis of tumor necrosis factor (TNF), which is a primary mediator of LPS lethality. We measured LPS-stimulated macrophage TNF release in the presence of serum from hypophysectomized rats to detect the appearance of an inducible 65 kDa protein that enhances TNF release. Surprisingly, the N-terminal amino acid sequence analysis of the isolated, purified protein revealed its identity as hemoglobin. Hypophysectomy significantly increases serum hemoglobin levels (control hemoglobin = 103 ± 18 μg/mL versus hypophysectomized serum hemoglobin = 279 ± 13 μg/mL; p

ISSN:1073-2322    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

The underlying mechanisms of hemoglobin (Hb)-induced vasoconstriction are not yet well understood. The aim of this study was to elucidate the influence of nitric oxide (NO) and endothelin (ET) on Hb-induced pulmonary vasoconstriction. Therefore, an autologous Hb preparation was administered into isolated rabbit lungs, in which pulmonary artery pressure (PAP) and weight gain was monitored. Either glyceroltrinitrate (GTN; 10-5M; n = 6), l-arginine (10-2M; n = 6), l-NAME (10-4M; n = 6), ETA- or ETB- receptor antagonists (BQ123, 10-6M, n = 6) or (BQ788, 10-6M, n = 6) were added to the perfusion fluid and NOxand thromboxane A2levels were measured. Results: In the control group the Hb-stimulation resulted in a pressure response up to 25.1 ± 2.1 mmHg (p< .05), which was 136 ± 6% of the reference value. The PAP increase was significantly (p< .05) blunted after GTN (71 ± 5%), l-arginine (93 ± 6%) and BQ788(88 ± 7%). Pretreatment with l-NAME (139 ± 13%) or BQ123(115 ± 9%) did not show significant changes in PAP. Conclusion: The reduction of the Hb-induced pulmonary hypertension by NO-donors points toward the inactivation of NO by free hemoglobin. Likewise, ETB-receptor mediated vasoconstrictive effects without changes in NOxconcentrations seem to play a pathogenetic role in the Hb-induced pulmonary vasoconstriction.

ISSN:1073-2322    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

The goal of these experiments was to test the hypothesis that after a nonlethal episode of hemorrhagic shock, factors carried in the mesenteric lymph would promote endothelial cell injury and activate neutrophils to a greater extent than portal vein plasma. Catheters were placed in the efferent lymphatic duct draining the mesenteric lymph node complex, after which male rats were subjected to sham or actual shock (30 mmHg for 90 min), and lymph was collected. Portal vein plasma was collected from the sham-shock and shocked rats at 6 h post-shock or sham-shock. When the effect of lymph or portal blood plasma was tested on endothelial cell (HUVEC) monolayer permeability, it was found that post-shock lymph, but not post-shock portal vein plasma, increased HUVEC permeability to both 10 kDa and 40 kDa permeability probes. Subsequent experiments documented that only post-shock lymph was cytotoxic to endothelial cells as manifest both by decreased trypan blue dye exclusion and the increased release of Chromium-51 from chromium-loaded endothelial cells. Furthermore post-shock lymph induced a greater increase in neutrophil superoxide formation than pre-shock lymph, pre-shock, or post-shock portal vein plasma. Lastly, neutrophil-mediated endothelial cell injury was potentiated by the presence of post-shock lymph, and the magnitude of HUVEC injury was greater in endothelial cells incubated with post-shock lymph plus neutrophils than in monolayers incubated with post-shock lymph or neutrophils alone. These results suggest that post-shock lymph is cytotoxic to endothelial cells and activates neutrophils. Since the lung is the first organ that is exposed to mesenteric lymph, lung injury after hemorrhagic shock may be mediated by factors contained in mesenteric lymph.

ISSN:1073-2322    

出版商:OVID    

年代:1998

数据来源: OVID

ISSN:1073-2322    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Following resuscitation (RES) from hemorrhagic shock (HEM), intestinal microvessels develop progressive vasoconstriction that impairs mucosal blood flow, despite central hemodynamic RES. These events might have clinical consequences secondary to occult intestinal ischemia. We hypothesized that the microvascular impairments were due to progressive endothelial cell dysfunction and an associated reduction in the dilator, nitric oxide (NO), following HEM/RES. Male Sprague-Dawley rats, were monitored for central hemodynamics and the terminal ileum was studied within vivovideomicroscopy. HEM was 50% of baseline mean arterial pressure (MAP) for 60 min, and RES was with shed blood + 1 volume of normal saline (NS), Following HEM/RES, acetylcholine (10-7, 10-5M) was topically applied and ileal inflow (A1) and premucosal arteriolar diameters were measured to assess endothelial-cell function at 60 and 120 min post-RES. Normalization of MAP, cardiac output, and heart rate demonstrated adequate systemic resuscitation. Post-RES vasoconstriction developed in A1 (-25%) and premucosal (-28%) arterioles with an associated reduction in A1 flow (-47%). However, there was a selective impairment of endothelialdependent dilation that was manifested only in the smaller premucosal arterioles and not in the inflow, A1 arterioles. This suggests that multiple mechanisms are involved in the development of the post-RES vasoconstriction. The premucosal response was likely mediated by endothelial cell dysfunction, while the A1 response was probably the result of enhanced vasoconstrictor forces. This early microvascular dysfunction might contribute to the late sequelae of intestinal ischemia and might alter microvascular responses to subsequent systemic insults.

ISSN:1073-2322    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Lipopolysaccharide (LPS) is a primary agent of sepsis that damages the vascular endothelium. Endothelial cell proliferation is key to the repair of damaged endothelium, and drugs that counteract the antiproliferative impact of LPS on endothelial cells should be beneficial. Because LPS exerts much of its cytotoxicity by generating reactive oxygen and nitrogen intermediates, it would be helpful to know whether therapeutic antioxidant thiols maintain cell proliferation in injured endothelium. In this study, it was found that LPS inhibited bovine aortic endothelial cell proliferation by inducing apoptosis and by decreasing DNA synthesis. Because of its benefit to irradiated endothelial cells, we then treated the cells with a radio and chemoprotective aminothiol, WR-1065 ([N-2-mecaptoethyl]-1–3-diaminopropane, the active form of Amifostine®/Ethyol®). WR-1065 attenuated the inhibition of DNA synthesis caused by LPS exposure. The disulfide of WR-1065, WR-33278, was tested and shown to both promote DNA synthesis and inhibit apoptosis. The effectiveness of the disulfide suggests that the reduction of cytotoxicity does not necessarily result from the scavenging of free radicals. These findings demonstrate a novel role for aminothiols in promoting DNA synthesis and lowering apoptosis in endothelium injured with LPS.

ISSN:1073-2322    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

In septic patients, lipopolysaccharide (LPS) damages the vascular endothelium, which manifests as tissue edema and impaired healing. This pathology occurs when LPS distorts endothelial cell morphology partly by generating free radicals. A radio protector that scavenges free radicals, the aminothiol WR-1065 ([N-2-mercaptoethyl]-1–3-diaminopropane) was found in a prior study to normalize the morphology of irradiated endothelial cells (Mooteri SN, Podolski JL, Drab EA, et al:Radiat Res145:217–224, 1996). The aim of this study was to determine whether WR-1065 also normalized endothelial cell morphology following exposure to LPS. For this aim, portions of bovine aortic endothelial cell cultures were denuded and exposed to LPS at 1 ng/mL. After 30 min, the apical membrane expressed increased integrin receptor to fibronectin, α5β1. After 5 h, the morphology of the cells at the leading edge was distorted, and cell-cell contact was lessened. Also, filamentous actin-containing stress fibers were dissipated; however, filamentous actin content per cell was unchanged. Treatment with 2 mM WR-1065 for 2 h prior to LPS exposure attenuated the increased expression of α5β1and promoted cell-cell contact in the migrating endothelial cells. WR-1065 also promoted the retention of stress fibers and actin cytoskeletal shape in cells treated with LPS. Thus, LPS distorted endothelial cell morphology after increasing apical membrance expression of α5β1and dissipating stress fibers, effects prevented by WR-1065.

ISSN:1073-2322    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

We previously showed that incubation in carbon dioxide (CO2), but not air or helium (He), markedly decreased macrophage intracellular pH (pH1) and resulted in reversible inhibition of lipopolysaccharide- (LPS) stimulated tumor necrosis factor (TNF) and interleukin-1 release. We sought to determine whether carbonic anhydrase inhibition with acetazolamide would prevent CO2-mediated inhibition of LPS-stimulated TNF release. Murine peritoneal macrophages were treated with acetazolamide for 1 h under control atmosphere (95% air/5% CO2) and then switched to incubator modules containing: 1) 80% CO2/20% O2, 2) 80% He/20% O2, or 3) 100% air. Before transfer to experimental atmospheric conditions the macrophages were stimulated with 0 or 1 μg/mL of LPS (Escherichiacoli 0111B4). Supernatant TNF was measured 4 h later by bioassay. In parallel experiments LPS-stimulated cytokine mRNA was estimated using reverse transcriptase polymerase chain reaction (RT-PCR) 2 h after LPSstimulated. Viability was determined using dye uptake. Incubation in CO2or helium had no effect on TNF production in the absence of LPS. In the absence of acetazolamide CO2produced marked inhibition of LPS-stimulated TNF release, but this was not blocked by the presence of acetazolamide. This CO2-mediated inhibition of TNF was associated with normal levels of TNF mRNA. In acetazolamide-treated macrophages, LPS resulted in a dose-dependent inhibition of TNF release, but not TNF mRNA induction by LPS. Factors that alter intracellular pH regulation may modulate LPS-stimulated cytokine production.

ISSN:1073-2322    

出版商:OVID    

年代:1998

数据来源: OVID