Mediators Tumor Necrosis Factor-alpha Research Articles

Inflammatory mediators are associated with 1-year mortality in critical limb ischemia

The atherosclerotic process has inflammatory features. Patients with peripheral atherosclerosis and critical limb ischemia have a poor prognosis. This study evaluated the hypothesis that inflammatory markers are associated with mortality among patients admitted to the hospital because of critical limb ischemia. This was a prospective, single-center, 1-year, follow-up study of 259 consecutive patients with critical limb ischemia who were admitted to a secondary referral center of vascular diseases. Interventions included evaluation of intercurrent disease, ankle and arm blood pressures, plasma glucose and lipid levels, plasma homocysteine, cardiolipin antibodies, resistance to activated protein C, plasma endothelin-1, and the inflammatory mediators tumor necrosis factor-alpha, interleukin-6, neopterin, high-sensitivity C-reactive protein, CD40 ligand, and 8-iso-prostaglandin F alpha in plasma. The main outcome measure was total mortality and causes of death assessed 1 year after admission. During the first year after admission, 61 patients (24%) died. These patients were older (P < .0001), showed a higher leukocyte count (P = .0011) and levels of serum creatinine (P < .0001), lower levels of high-density lipoprotein (HDL) cholesterol (P = .003) and frequency of active treatment (P = .014) than the 198 (76%) survivors. More nonsurvivors had gangrene (P < .0001), and fewer (P = .004) had lipid-lowering treatment. The plasma levels of interleukin-6 (P < .0001), tumor necrosis factor-alpha (P < .0001), neopterin (P < .0001), and high-sensitivity C-reactive protein (P = .002) at admission for critical limb ischemia were all significantly lower in the survivors, whereas there was no difference concerning CD40 ligand. In logistic regression adjusted for age, sex, lipid-lowering therapy, active treatment, gangrene, leukocyte count, creatinine, and serum HDL cholesterol, the inflammatory mediators tumor necrosis factor-alpha (P = .0084), neopterin (P = .0035), but not interleukin-6 (P = .585) or high-sensitivity C-reactive protein (P = .314) were independent risk variables of death within 1 year. Increased age, leukocyte count, creatinine, and inflammatory mediators, together with gangrene, were associated with 1-year mortality despite intervention in critical limb ischemia. For tumor necrosis factor-alpha and neopterin in plasma, this association was independent of the other parameters.

Glucocorticoids suppress transcriptional up‐regulation of bradykinin receptors in a murine in vitro model of chronic airway inflammation

Glucocorticoids are effective drugs for controlling symptoms and airway inflammation in respiratory diseases such as asthma and chronic obstructive pulmonary disease. However, the mechanisms behind their effects are not fully understood. We have recently demonstrated that prolonged exposure to the pro-inflammatory mediator tumour necrosis factor-alpha (TNF-alpha) markedly enhanced contractile responses to des-Arg9-bradykinin (selective bradykinin B1 receptor agonist) and bradykinin (selective bradykinin B2 receptor agonist) in murine airways. This increase was paralleled with elevated mRNA levels for bradykinin B1 and B2 receptors, a process involving intracellular mitogen-activated protein kinase pathways. To investigate the effects of glucocorticoids on the TNF-alpha up-regulated bradykinin B1 and B2 receptor response. Tracheal segments from BALB/c J mice were cultured with and without TNF-alpha, in the absence and presence of the transcriptional inhibitor actinomycin D or the glucocorticoid, dexamethasone. The contractile response induced by des-Arg9-bradykinin and bradykinin was subsequently assessed in a myograph system and mRNA for bradykinin B1 and B2 receptors was quantified using real-time polymerase chain reaction. Actinomycin D abolished and dexamethasone concentration-dependently suppressed the TNF-alpha-induced enhancement of the des-Arg9-bradykinin and bradykinin responses. This was paralleled by a reduction of the mRNA expression for the bradykinin B1 and B2 receptors. The presented data suggests the involvement of transcriptional mechanisms in the up-regulation of bradykinin B1 and B2 receptors during asthmatic airway inflammation, as well as in their down-regulation following glucocorticoid treatment.

Rhesus brain microvascular endothelial cells are permissive for rhesus cytomegalovirus infection

Endothelial cells (EC) are an important cell type for human cytomegalovirus (CMV) pathogenesis. To characterize better the role of EC in primate CMV natural history, rhesus macaque microvascular EC (MVEC) were purified from fetal brain and analysed for infectivity by rhesus cytomegalovirus (RhCMV). Rhesus brain MVEC (BrMVEC) in culture were positive for von Willebrand factor and CD105 expression, uptake of acetylated low-density lipoprotein, and formation of capillary-like tubules on Matrigel, all phenotypic hallmarks of EC. BrMVEC were fully permissive for infection by RhCMV strain 68-1, and detectable plaques formed within 5 days of infection. Infectivity of BrMVEC by RhCMV could be reduced, but not abolished, by treatment of cells either before or during infection with pro-inflammatory mediators tumour necrosis factor-alpha, interleukin-1beta or phorbol 12-myristate 13-acetate. These results demonstrate that in vitro infection of rhesus BrMVEC is a dynamic process that is influenced by activation conditions.

Chinchilla Middle Ear Epithelial Mucin Gene Expression in Response to Inflammatory Cytokines

To review the importance of mucin on a molecular level in the understanding of the pathophysiology of otitis media and to present new data demonstrating differential up-regulation of specific mucin genes during inflammation of middle ear epithelium. Primary chinchilla middle ear epithelial cultures (CMEECs) were established and exposed to tumor necrosis factor alpha and interleukin 1beta. Expression of chinchilla mucin genes 1, 2, 4, and 5AC was analyzed by means of reverse transcriptase-polymerase chain reaction after this exposure and compared with that of controls. Mucin secretion was also characterized by means of exclusion chromatography and liquid scintillation. The CMEECs exposed to interleukin 1beta and tumor necrosis factor alpha demonstrated significant up-regulation of mucin gene 2 (P = .005 and P = .007, respectively) and trends suggestive of up-regulation of mucin gene 5AC compared with the controls. These CMEECs also demonstrated significant increases in secretion of mucin compared with controls. Mucin genes 1 and 4 did not demonstrate up-regulation. In CMEECs, the inflammatory mediators tumor necrosis factor alpha and interleukin 1beta cause a differential up-regulation and expression of mucin genes. Elucidating the effect of specific cytokines on the regulation of mucin secretion in the middle ear is vital to understanding the pathophysiology of otitis media. A greater understanding of these mechanisms and variations between individuals and pathogens has the potential to significantly alter the approach and management of otitis media in children and lead to novel therapeutic interventions.

Influence of Eicosapentaenoic Acid, an Omega-3 Fatty Acid, on Ultraviolet-B Generation of Prostaglandin-E2 and Proinflammatory Cytokines Interleukin-1β, Tumor Necrosis Factor–α, Interleukin-6 and Interleukin-8 in Human Skin In Vivo¶

Dietary omega-3 polyunsaturated fatty acids (omega-3 PUFA) reduce sunburn, an acute inflammatory response, in humans. We assessed whether this may be mediated by reduced ultraviolet-B (UV-B) induction of proinflammatory mediators tumor necrosis factor-alpha (TNF-alpha), interleukin (IL)-1 beta, IL-6, IL-8 and prostaglandin (PG)E(2) in healthy skin. In a double-blind, randomized study, 28 humans received 4 g daily of 95% ethyl esters of eicosapentaenoic acid (EPA) or oleic acid (OA) orally for 3 months. Skin biopsies and suction blister fluid were taken from unexposed and UV-B-exposed skin and examined for mediator expression immunohistochemically and quantitatively by immunoassay; plasma levels were also assayed. The subjects taking EPA, but not OA, showed a significant rise in their minimal erythemal dose (MED) (data reported elsewhere). Before supplementation, irradiation with 3x MED UV-B increased blister fluid TNF-alpha, IL-6, IL-8 and PGE(2) at 16 h (all P < 0.001). No significant change occurred in baseline or UV-B-induced skin levels of cytokines after either supplement, whereas UV-B induction of PGE(2) was abolished after EPA but not OA. Immunohistochemical expression of the cytokines at baseline and after UV-B was unaltered by EPA and OA; circulating cytokine and PGE(2) levels were also unchanged. Hence, in healthy skin in vivo, there was no evidence that reduction of the sunburn response by EPA is mediated by the proinflammatory cytokines examined; abrogation of UV-B-generated PGE(2) may play a role.

Neuronal injury mediated via stimulation of microglial toll-like receptor-9 (TLR9).

Innate immune cells express toll-like receptor-9 (TLR9) and respond to unmethylated, CG dinucleotide motif-rich DNA released from bacteria during infection or endogenous cells during autoimmune tissue injury. Oligonucleotides containing CG dinucleotide (CpG-DNA) mimic the effect of unmethylated DNA and stimulate TLR9. CpG-DNA was cytotoxic to neurons in organotypic brain cultures. Neurotoxicity of CpG-DNA was mediated via microglial cells and started primarily from neurites as determined by time-lapse imaging of enhanced green fluorescent protein (EGFP)-transfected neurons. Cultured brain microglial cells expressed TLR9 and responded to CpG-DNA by production of the inflammatory mediators nitric oxide (NO) and tumor necrosis factor-alpha (TNF-alpha). Blockade of NO synthase and TNF-alpha prevented damage of neurites and neurotoxicity of CpG-DNA. The data suggest that stimulation of microglia via TLR9 and subsequent release of NO and TNF-alpha is a major source of neurotoxicity in bacterial and autoimmune brain tissue injury.

Inflammatory mediators and radiographic changes in temporomandibular joints of patients with rheumatoid arthritis

The aim of this study was to investigate the relation between the inflammatory mediators tumor necrosis factor alpha (TNF ! ) and serotonin (5-HT), the inflammatory markers erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP), as well as rheumatoid factor (RF) and thrombocyte particle concentration (TPC) in blood versus temporomandibular joint (TMJ) radiographic changes in patients with clinical TMJ involvement by rheumatoid arthritis (RA). Twenty patients were included. Venous blood was collected for quantification of the mediators, markers, and TPC. The radiographic signs of erosion, flattening, sclerosis, subchondral pseudocyst, and osteophyte as well as radiographic grade were investigated with computed tomography. The median (IQR) plasma levels of TNF ! and 5-HT were 0 (13) r pg/mL and 13 (22) r nmol/L, respectively, while serum level of 5-HT was 1360 (874) nmol/L. ESR, CRP, and TPC were abnormally high in 53%, 25%, and 15% of the patients, respectively. The most frequent radiographic signs were sclerosis (75%), erosion (50%), and flattening (30%). Erosion was found to be associated with high TPC and flattening with high plasma level of TNF ! . In conclusion, patients with clinical TMJ involvement by RA show an association between high level of TPC and TNF ! in plasma versus radiographic signs of joint bone destruction.

Surfactant protein A decreases lung injury and mortality after murine marrow transplantation.

Surfactant protein A (SP-A), a collectin associated with surfactant lipids, can have immune modulatory effects. We hypothesized that exogenous and basal endogenous SP-A can function to suppress donor T-cell-dependent inflammation that occurs during the generation of idiopathic pneumonia syndrome after bone marrow transplantation (BMT). Wild-type and SP-A-deficient mice were conditioned with cyclophosphamide and lethal irradiation and then given allogeneic donor bone marrow plus inflammation-inducing spleen T cells. On Day 7 after BMT, bronchoalveolar lavage fluids from SP-A-deficient mice contained increased numbers of inflammatory cells and higher levels of proinflammatory mediators tumor necrosis factor-alpha, interferon-gamma, and nitric oxide than wild-type mice. Exaggerated inflammation in SP-A-deficient mice was associated with decreased dynamic lung compliance and increased donor T-cell-dependent mortality (P = 0.0007, n = 10). Nitrative stress in alveolar macrophages from SP-A(-/-)-conditioned BMT recipients was higher than for SP-A(+/+) mice. Similarly, mice treated with transtracheal human SP-A (50 micro g), instilled on Day 4 after BMT during a time of in vivo donor T cell activation, exhibited decreased inflammation and improved early survival compared with buffer-instilled mice. We concluded that basal endogenous SP-A and enhanced alveolar SP-A level modulate donor T-cell-dependent immune responses and prolong survival after allogeneic BMT.

Regulation of the Hypoxia-inducible Factor 1α by the Inflammatory Mediators Nitric Oxide and Tumor Necrosis Factor-α in Contrast to Desferroxamine and Phenylarsine Oxide

Hypoxic/ischemic conditions provoke activation of the hypoxia-inducible factor-1 (HIF-1), which functions as a transcription factor. HIF-1 is composed of the HIF-1alpha and -beta subunits, and stability regulation occurs via accumulation/degradation of HIF-1alpha with the notion that a prolyl hydroxylase accounts for changes in protein level. In addition, there is evidence that HIF-1 is up-regulated by diverse agonists during normoxia. We investigated the impact of inflammatory mediators nitric oxide (NO) and tumor necrosis factor-alpha (TNF-alpha) on HIF-1alpha regulation. For comparison, LLC-PK(1) cells were exposed to hypoxia, stimulated with desferroxamine (DFX, known to mimic hypoxia), and the thiol-cross-linking agent phenylarsine oxide (PAO). Although all stimuli elicited HIF-1alpha stabilization with differences in the time-dependent accumulation pattern, significant variations appeared with regard to signaling. With the use of a superoxide anion (O(2-)) generator, we established an O(2-)-sensitive pathway that blocked HIF-1alpha stabilization in response to NO and TNF-alpha while DFX- and PAO-evoked HIF-1alpha stabilization appeared O(2-)-insensitive. NO and TNF-alpha signaling required phosphorylation events, especially activation of the phosphatidylinositol 3-kinase/Akt, which is in contrast to DFX and PAO. Based on HIF-1-dependent luciferase reporter gene analysis, it was found that, in contrast to NO and TNF-alpha, PAO resembled a stimulus that induced a dysfunctional HIF-1 complex. These data indicate that diverse agonists activate HIF-1alpha under normoxic conditions by employing different signaling pathways.

Enhanced cyclooxygenase-2 mRNA expression in human gingival fibroblasts induced by cell contact with human lymphocytes.

Prostaglandins, especially prostaglandin E2 (PGE2), play a crucial role in the pathogenesis of periodontal disease. We have previously reported that inflammatory mediators interleukin-1 (IL-1) and tumor necrosis factor alpha (TNFalpha) increase the production of PGE2 in human gingival fibroblasts. In this study, we investigated the effect of cell-to-cell interactions between gingival fibroblasts and lymphocytes on PGE2 production by using co-culture technique. Cell-to-cell contact between gingival fibroblasts and lymphocytes synergistically enhanced the production of PGE2 in co-cultures. In contrast to lymphocytes, the cyclooxygenase-2 (COX-2) mRNA expression in gingival fibroblasts was strongly enhanced following cell contact between gingival fibroblasts and lymphocytes. The level of COX-1 mRNA expression, however, was not affected either in gingival fibroblasts or in lymphocytes by the interactions between fibroblasts and lymphocytes. The study demonstrates that cell contact between gingival fibroblasts and lymphocytes strongly stimulates PGE2 production partly due to enhanced COX-2 mRNA expression in gingival fibroblasts. The cell-to-cell contact between gingival fibroblasts and lymphocytes should be considered as an important regulatory aspect for the enhancement of PGE2 in periodontal disease.

ADAM17 but not ADAM10 mediates tumor necrosis factor-alpha and L-selectin shedding from leukocyte membranes.

The release of tumor necrosis factor-alpha (TNF-alpha) from cellular membranes has been shown by different laboratories to be controlled by a disintegrin and metalloprotease, ADAM10 or ADAM17. In contrast, only ADAM17 has shown to be involved in L-selectin shedding. To determine the specific roles of ADAM10 and ADAM17 in the processing of TNF-alpha and L-selectin shedding, antisense oligonucleotides (ASO) targeting both ADAM10 and ADAM17 were identified. We show that ISIS 16337 reduces ADAM17 mRNA and ISIS 100750 reduces ADAM10 mRNA in a sequence-specific and dose-dependent manner in both Jurkat and THP-1 cells. The ADAM17 ASO (ISIS 16337) inhibited both TNF-alpha secretion in THP-1 cells and L-selectin shedding in Jurkat cells, whereas the ADAM10 ASO (ISIS 100750) did not significantly inhibit release of either protein. These results suggest that ADAM17 is one of the major metalloproteases involved in L-selectin shedding as well as TNF-alpha processing. The biologic substrates for ADAM10 in Jurkat and THP-1 cells remain to be elucidated.

Effect of a short-term in vitro exposure to the marine toxin domoic acid on viability, tumor necrosis factor-alpha, matrix metalloproteinase-9 and superoxide anion release by rat neonatal microglia

BackgroundThe excitatory amino acid domoic acid, a glutamate and kainic acid analog, is the causative agent of amnesic shellfish poisoning in humans. No studies to our knowledge have investigated the potential contribution to short-term neurotoxicity of the brain microglia, a cell type that constitutes circa 10% of the total glial population in the brain. We tested the hypothesis that a short-term in vitro exposure to domoic acid, might lead to the activation of rat neonatal microglia and the concomitant release of the putative neurotoxic mediators tumor necrosis factor-α (TNF-α), matrix metalloproteinases-2 and-9 (MMP-2 and -9) and superoxide anion (O2-).ResultsIn vitro, domoic acid [10 μM-1 mM] was significantly neurotoxic to primary cerebellar granule neurons. Although neonatal rat microglia expressed ionotropic glutamate GluR4 receptors, exposure during 6 hours to domoic acid [10 μM-1 mM] had no significant effect on viability. By four hours, LPS (10 ng/mL) stimulated an increase in TNF-α mRNA and a 2,233 % increase in TNF-α protein In contrast, domoic acid (1 mM) induced a slight rise in TNF-α expression and a 53 % increase (p < 0.01) of immunoreactive TNF-α protein. Furthermore, though less potent than LPS, a 4-hour treatment with domoic acid (1 mM) yielded a 757% (p < 0.01) increase in MMP-9 release, but had no effect on MMP-2. Finally, while PMA (phorbol 12-myristate 13-acetate) stimulated O2- generation was elevated in 6 hour LPS-primed microglia, a similar pretreatment with domoic acid (1 mM) did not prime O2- release.ConclusionsTo our knowledge this is the first experimental evidence that domoic acid, at in vitro concentrations that are toxic to neuronal cells, can trigger a release of statistically significant amounts of TNF-α and MMP-9 by brain microglia. These observations are of considerable pathophysiological significance because domoic acid activates rat microglia several days after in vivo administration.

Proapoptotic Fas ligand is expressed by normal kidney tubular epithelium and injured glomeruli.

Fas ligand (FasL) is a cell membrane cytokine that can promote apoptosis through activation of Fas receptors. Fas receptor activation induces glomerular cell apoptosis in vivo and participates in tubular cell death during acute renal failure. However, there is little information on the expression of FasL in the kidney. This study reports that FasL mRNA and protein are present in normal mouse and rat kidney. In situ hybridization and immunohistochemistry showed that proximal tubular epithelium is the main site of FasL expression in the normal kidney. In addition, increased total kidney FasL mRNA and de novo FasL protein expression by glomerular cells were observed in two different models of glomerular injury : rat immune-complex proliferative glumerulonephritis and murine lupus nephritis. Both full-length and soluble FasL were increased in the kidneys of the mice with nephritis. Cultured murine proximal tubular epithelial MCT cells and primary cultures of murine tubular epithelial cells expressed FasL mRNA and protein. Tubular epithelium-derived FasL induced apoptosis in Fassensitive lymphoid cell lines but not in Fas-resistant lymphoid cell lines. By contrast, MCT cells grown in the presence of the survival factors of serum were resistant to FasL, and only became partially sensitive to apoptosis induced by high concentrations (100 ng/ml) of FasL upon serum deprivation. However, MCT cells stimulated with inflammatory mediators (tumor necrosis factor-alpha, interferon-gamma, and lipopolysaccharide) increased cell surface Fas expression and were sensitized to apoptosis induced by FasL (FasL 55 +/- 5% versus control 8.3 +/- 4.1% apoptotic cells at 24 h, P < 0.05). Cytokine-primed primary cultures of tubular epithelial cells also acquired sensitivity to FasL-induced apoptosis. These results suggest that FasL expression by intrinsic renal cells may play a role in cell homeostasis in the normal kidney and during renal injury.

Protein kinase C-alpha mediates endothelial barrier dysfunction induced by TNF-alpha.

We tested the hypothesis that protein kinase C-alpha (PKC-alpha) mediates tumor necrosis factor-alpha (TNF-alpha)-induced alterations in permeability of pulmonary microvessel endothelial monolayers (PEM). The permeability of PEM was assessed by the clearance rate of Evans blue-labeled albumin. PEM lysates were analyzed for PKC-alpha mRNA (Northern cDNA blot), protein (Western immunoblot), and activity (translocation and phosphorylation of myristoylated arginine-rich C kinase substrate). Incubation of PEM with TNF-alpha (1,000 U/ml) for 4 h resulted in increases in 1) PKC-alpha protein, 2) cytoskeletal-associated PKC-alpha, 3) PKC-alpha activity, and 4) permeability to albumin. The TNF-alpha-induced increase in PKC-alpha protein, PKC-alpha activity, and permeability was prevented by a 4-h pretreatment with PKC-alpha antisense oligonucleotide but not by the scrambled nonsense oligonucleotide. The TNF-alpha-induced increase in permeability to albumin was prevented by myristoylated protein kinase C inhibitor (an inhibitor of PKC-alpha/beta, 100 microM) and calphostin (an inhibitor of the classic and novel PKC isotypes, 200 nM). The treatment with calphostin from 0.5 to 3.0 h after TNF-alpha still prevented barrier dysfunction induced by 4 h of TNF-alpha treatment. The data indicate that prolonged activation of PKC-alpha, maintained by a translation-dependent pool of PKC-alpha protein, mediates TNF-alpha-induced increases in endothelial permeability in PEM.

Role of inflammatory mediators in priming, activation, and deformability of bovine neutrophils.

To determine the capacity of inflammatory mediators tumor necrosis factor-alpha (TNF-alpha), interleukin-8 (IL-8), platelet-activating factor (PAF), lipopolysaccharide (LPS), and leukotoxin to prime, activate, or alter deformability of adult bovine neutrophils. Blood collected from 5 healthy adult Holstein cows. Isolated neutrophils or whole blood was incubated with TNF-alpha, IL-8, PAF, LPS, or leukotoxin, and neutrophil chemiluminescence, degranulation, deformability, shape change, CD11b expression, and size distribution was measured. Incubation with TNF-alpha, IL-8, PAF, and LPS primed neutrophils for oxygen radical release but caused minimal oxygen radical release by themselves. None of the inflammatory mediators induced degranulation. Incubation with TNF-alpha and PAF resulted in a decrease in neutrophil deformability and induced shape change in neutrophils. Incubation with PAF consistently resulted in an increase in neutrophil size as measured by use of flow cytometry. Only IL-8 caused an increase in expression of CD11b by neutrophils. Inflammatory mediators tested had minimal effects on neutrophil oxygen radical production or degranulation but did prime neutrophils for oxygen radical production. Incubation with PAF and TNF-alpha caused a decrease in neutrophil deformability and altered neutrophil shape and size. Results of our study indicate that PAF- and TNF-alpha-induced changes in neutrophil deformability and size may cause integrin- and selectin-independent trapping of neutrophils in the lungs of cattle with pneumonic pasteurellosis.

Dual role of interleukin-10 in murine Lyme disease: regulation of arthritis severity and host defense.

In the murine model of Lyme disease, C3H/He mice exhibit severe arthritis while C57BL/6N mice exhibit mild lesions when infected with Borrelia burgdorferi. Joint tissues from these two strains of mice harbor similar concentrations of B. burgdorferi, suggesting that the difference in disease severity reflects differences in the magnitude of the inflammatory response to B. burgdorferi lipoproteins. Stimulation of bone marrow macrophages from C3H/HeN mice with the B. burgdorferi lipoprotein OspA resulted in higher-level production of the inflammatory mediators tumor necrosis factor alpha, nitric oxide, and interleukin-6 (IL-6) than that of macrophages from C57BL/6N mice. In contrast, macrophages from C57BL/6N mice consistently produced larger amounts of the anti-inflammatory cytokine IL-10 than did C3H/HeN macrophages. Addition of recombinant IL-10 suppressed the production of inflammatory mediators by macrophages from both strains. IL-10 was found to modulate B. burgdorferi-induced inflammation in vivo, since C57BL/6J mice deficient in IL-10 (IL-10-/-) developed more severe arthritis than wild-type C57BL/6J mice. The increase in arthritis severity was associated with a 10-fold decrease in the number of B. burgdorferi organisms present in ankle tissues from IL-10-/- mice. These findings suggest that in C57BL/6 mice, IL-10-dependent regulation of arthritis severity occurs at the expense of effective control of bacterial numbers.

Involvement of endogenous interleukin-10 and tumor necrosis factor-alpha in renal ischemia-reperfusion injury.

Ischemia followed by reperfusion is a common clinical event associated with a pro-inflammatory response leading to organ dysfunction. The aim of the present study is to evaluate the interplay between this pro-inflammatory response and apoptosis. We investigated the role of the pro-inflammatory mediator tumor necrosis factor-alpha (TNF-alpha) and the anti-inflammatory mediator interleukin-10 (IL-10) in inflammation and apoptosis after renal ischemia reperfusion. Male Swiss mice were subjected to 45 min of ischemia followed by reperfusion and subsequently administered neutralizing Abs against either TNF-alpha (TN3), IL-10 (JES5-2A5) or control. After 1 day of reperfusion, anti-TNF-alpha treatment reduced whereas anti-IL-10 treatment exacerbated postischemic renal injury, inflammation, and, to a lesser extent, apoptosis as measured by changes in blood urea nitrogen content, immunohistologically detectable renal TNF-alpha protein and neutrophils, histological integrity of renal parenchyma, and DNA ladder formation. Furthermore, anti-IL-10 treatment enhanced major histocompatibility complex class I and II expression at day 7 as measured by enzyme immunoassay and immunohistology. These data indicate that the extent of reperfusion-induced apoptosis is modulated by the inflammatory response, during which locally produced TNF-alpha plays a significant role in the development of tissue injury. Subsequently, this pro-inflammatory reaction is followed by endogenous production of the anti-inflammatory cytokine IL-10, which serves as a physiological counterbalance to the effects of TNF-alpha. These novel pathophysiological insights may provide new basis for the development of tools for limiting ischemia and reperfusion injury.

Oral spermine administration inhibits nitric oxide-mediated intestinal damage and levels of systemic inflammatory mediators in a mouse endotoxin model.

Enhanced intestinal nitric oxide production observed during sepsis is thought to play a central role in lipopolysaccharide-induced intestinal damage. In contrast intestinal polyamines, both from endogenous and exogenous origin, are essential for the maintenance of mucosal integrity. Polyamines have been shown to inhibit lipopolysaccharide-induced nitric oxide release in vitro and have been claimed to exert additional antiinflammatory actions. In this study, the effect of the polyamine spermine on the release of the proinflammatory mediators nitric oxide and tumor necrosis factor-alpha by a murine macrophage cell line was investigated. Furthermore, we investigated whether oral spermine administration inhibits lipopolysaccharide-induced intestinal inducible nitric oxide synthase and nitrotyrosine expression and modulates the release of inflammatory mediators. Our results show that although spermine inhibited lipopolysaccharide-induced nitric oxide release in a murine macrophage cell line, no effect on tumor necrosis factor-alpha release was observed. In addition, oral spermine administration inhibited intestinal inducible nitric oxide synthase and nitrotyrosine expression suggesting a protective effect of spermine on lipopolysaccharide-induced intestinal damage. In parallel a decrease in serum levels of the proinflammatory mediators nitrate, nitrite, and interferon-gamma and an increase in the antiinflammatory cytokine interleukin-10 was observed, although tumor necrosis factor-alpha levels were unaffected. These results indicate that spermine inhibits lipopolysaccharide-induced nitric oxide release in vitro as well as in vivo. Further, intraluminally derived polyamines modulate the systemic immune response. It is concluded that oral spermine administration might have therapeutic perspectives for several disorders characterized by systemic inflammation and intestinal damage.

Proinflammatory mediator release in response to particle challenge: Studies using the bone harvest chamber

This study reports on the effects of phagocytosable particles on proinflammatory mediator release in an animal model. Bone harvest chambers (BHCs) were implanted bilaterally into mature rabbits; phagocytosable ultrahigh molecular weight polyethylene (UHMWPE) and polystyrene (PS) particles, and the carrier sodium hyaluronate (HE) were tested for their ability to stimulate proinflammatory mediator release. Tissues were harvested after 3, 4, or 6 weeks. Retrieved tissues were placed into culture medium. The release of the proinflammatory mediators interleukin-6 (IL-6), interleukin-1beta (IL-1β), and tumor necrosis factor alpha (TNF-α) into the culture medium was assessed using bioassays. DNA content and dry weights were also measured. The maximal biological response to the PE particles with respect to TNF-α and IL-1β was observed at three weeks with 11- and fivefold stimulations over controls, respectively. The maximal response to PE particles with respect to IL-6 was observed at 4 weeks with a twofold stimulation over controls. Similar patterns were seen with PS particles; however, PE particles stimulated higher cytokine release. PE particles stimulated the expression of IL-1β, IL-6, and TNF-α in the BHC model. Cell culture and human retrieval studies also implicate these proinflammatory mediators in loosening and osteolysis of total joint replacements. Thus, the BHC is a useful in vivo model to document the effects of particles on the evolution of biological responses to particulate debris. © 1999 John Wiley & Sons, Inc. J Biomed Mater Res (Appl Biomater) 48: 434–439, 1999

Proinflammatory mediator release in response to particle challenge: studies using the bone harvest chamber.

This study reports on the effects of phagocytosable particles on proinflammatory mediator release in an animal model. Bone harvest chambers (BHCs) were implanted bilaterally into mature rabbits; phagocytosable ultrahigh molecular weight polyethylene (UHMWPE) and polystyrene (PS) particles, and the carrier sodium hyaluronate (HE) were tested for their ability to stimulate proinflammatory mediator release. Tissues were harvested after 3, 4, or 6 weeks. Retrieved tissues were placed into culture medium. The release of the proinflammatory mediators interleukin-6 (IL-6), interleukin-1beta (IL-1beta), and tumor necrosis factor alpha (TNF-alpha) into the culture medium was assessed using bioassays. DNA content and dry weights were also measured. The maximal biological response to the PE particles with respect to TNF-alpha and IL-1beta was observed at three weeks with 11- and fivefold stimulations over controls, respectively. The maximal response to PE particles with respect to IL-6 was observed at 4 weeks with a twofold stimulation over controls. Similar patterns were seen with PS particles; however, PE particles stimulated higher cytokine release. PE particles stimulated the expression of IL-1beta, IL-6, and TNF-alpha in the BHC model. Cell culture and human retrieval studies also implicate these proinflammatory mediators in loosening and osteolysis of total joint replacements. Thus, the BHC is a useful in vivo model to document the effects of particles on the evolution of biological responses to particulate debris.