Interleukin-10 inhibits endotoxin-induced tissue factor mRNA production by human monocytes

Association between short-term heart rate variability and blood coagulation in patients with breast cancer

The purpose of this study was to investigate the relationship between heart rate variability (HRV), a non-invasive tool for evaluating autonomic function, and routine coagulation indices (RCIs) in patients with breast cancer (BC). Forty-six BC patients were enrolled in this study. Blood biochemistry tests were performed to extract RCIs, including prothrombin time (PT), activated partial thromboplastin time (APTT), and thrombin time (TT). Five-minute electrocardiograms were collected for analysis of HRV parameters (SDNN, RMSSD, LF, HF, LF n.u., HF n.u., LF/HF). Multiple linear regression models examined the relationship of HRV parameters with RCIs. RMSSD, LF n.u., HF n.u., LF/HF were significantly associated with PT. Specifically, the value of PT increased by 0.192 ± 0.091 or 0.231 ± 0.088 s, respectively for each 1 standard deviation (SD) increase in RMSSD or HF n.u.; it increased by 0.230 ± 0.088 or 0.215 ± 0.088 s, respectively for each 1 − SD decrease in LF n.u. or ln (LF/HF) (all P < 0.05). RMSSD was significantly associated with APTT, i.e., the value of APTT increased by 1.032 ± 0.470 s for each 1 − SD increase in RMSSD (P < 0.05). HRV parameters were associated with RCIs in patients with BC. These observations suggest that the autonomic nervous system and coagulation indices in BC patients are linked, potentially explaining the reason that they are both associated with the prognosis.

Tissue Engineered Vascular Graft Recipient Interleukin 10 Status Is Critical for Preventing Thrombosis

Tissue engineered vascular grafts (TEVGs) are a promising technology, but are hindered by occlusion. Seeding with bone-marrow derived mononuclear cells (BM-MNCs) mitigates occlusion, yet the precise mechanism remains unclear. Seeded cells disappear quickly and potentially mediate an anti-inflammatory effect through paracrine signaling. Here, a series of reciprocal genetic TEVG implantations plus recombinant protein treatment is reported to investigate what role interleukin-10, an anti-inflammatory cytokine, plays from both host and seeded cells. TEVGs seeded with BM-MNCs from wild-type and IL-10 KO mice, plus unseeded grafts, are implanted into wild-type and IL-10 KO mice. Wild-type mice with unseeded grafts also receive recombinant IL-10. Serial ultrasound evaluates occlusion and TEVGs are harvested at 14 d for immunohistochemical analysis. TEVGs in IL-10 KO mice have significantly higher occlusion incidence compared to wild-type mice attributed to acute (<3 d) thrombosis. Cell seeding rescues TEVGs in IL-10 KO mice comparable to wild-type patency. IL-10 from the host and seeded cells do not significantly influence graft inflammation and macrophage phenotype, yet IL-10 treatment shows interesting biologic effects including decreasing cell proliferation and increasing M2 macrophage polarization. IL-10 from the host is critical for preventing TEVG thrombosis and seeded BM-MNCs exert a significant anti-thrombotic effect in IL-10 KO mice.

IL-10 immunodepletion from meningococcal sepsis plasma induces extensive changes in gene expression and cytokine release in stimulated human monocytes

The severity of systemic meningococcal disease (SMD) correlates to plasma concentrations of LPS and IL-10, with the highest levels detected in non-survivors. Here, plasma from patients with SMD containing high and low concentrations of LPS were incubated with human monocytes before and after immunodepletion of IL-10 to study the effect of IL-10 on gene expression and cytokine release. Patient plasma containing IL-10 induced the expression of 1657 genes in human monocytes when compared with gene expression induced by low LPS plasma. After immunodepletion of IL-10, this number increased to 2260. By directly comparing the gene expression profiles induced before and after immunodepletion of IL-10, the presence of IL-10 differentially regulated 373 genes. Functional classes associated with these genes were cellular function and maintenance, cellular development, cellular growth and proliferation, cell-cell signaling and interaction and cellular movement. Immunodepletion of IL-10 resulted in down-regulation of genes of the leukocyte immunoglobulin-like receptor family, and up-regulation of genes of type I IFN signaling, TLR signaling, the inflammasomes, coagulation and fibrinolysis. Finally, immunodepletion of IL-10 increased the protein levels of IL-1β, IL-8, TNF-α, MIP-1α and MIP-1β. Data suggest that IL-10 in meningococcal sepsis plasma regulates a variety of genes and signaling pathways, likely leading to an overall inhibitory effect on the inflammatory response induced in meningococcal sepsis.

Effect of recombinant interleukin-10 on some haematological and biochemical parameters in a rat endotoxaemic model

Recombinant interleukin-10 (rIL10) has been found to suppress the synthesis of tumour necrosis factor (TNF), interleukin-1 (IL-1), interleukin-6 (IL-6) and tissue factor and to improve survival from experimental sepsis. The aim of this study was to evaluate the protective effect of rIL-10 on lipopolysaccharide-(LPS-) induced haematological and biochemical disturbances in rats. In the present study, 40 rats were used and divided equally into four groups. Group 1 (control group, C) was treated with 0.9% saline. Group 2: LPS was injected intravenously (1.6 mg/100 g), Group 3 received rIL10 treatment (125 μg/kg) 2 min before 0.9% saline injection, Group 4 received rIL10 treatment 2 min before endotoxin treatment. When compared with the controls, platelet count, leukocyte count (with a marked neutrophilia and lymphopenia) and fibrinogen were decreased, while activated partial thromboplastin time (APTT) and prothrombin time (PT) were prolonged in the endotoxaemic rats. In addition, LPS caused statistically significant increases in plasma aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities as well as creatinine, cholesterol and triglyceride concentrations, while it caused a statistically significant decrease in glucose, total protein and albumin levels as compared to the control group. On the other hand, rIL10 significantly suppressed disturbances in the haematological and biochemical parameters associated with endotoxaemia. As a result, rIL10 may be efficacious in preventing haematological disorders, tissue damage and changes in lipid, protein and carbohydrate metabolism in endotoxaemia.

Role of inflammation-related gene polymorphisms in patients with central retinal vein occlusion

OBJECTIVE

Central retinal vein occlusion (CRVO) is a vision-threatening disease, primarily occurring among patients aged more than 60 years. Several risk factors, including arterial hypertension and diabetes mellitus, have been identified. Compression of the central retinal vein by an atherosclerotic retinal artery at the lamina cribrosa also has been implicated in the pathogenesis of the disease. Functional gene polymorphisms of cytokines or chemokines previously shown to affect atherogenesis or hemostasis are potential risk factors for CRVO. The present study investigates a hypothesized association between inflammation-related gene polymorphisms and the presence of CRVO in a relatively large cohort of patients.

DESIGN

Case-control study.

PARTICIPANTS

The study group consisted of 315 patients with CRVO and 335 control subjects.

METHODS

Determination of genotypes was done by 5' exonuclease assay (TaqMan).

MAIN OUTCOME MEASURES

Genotypes of interleukin (IL)1β -511C>T, IL1 receptor antagonist (IL1RN) 1018T>C, IL4 -584C>T, IL6 -174G>C, IL10 -592C>A, IL18 183A>G, tumor necrosis factor (TNF)-α -308G>A, monocyte chemoattractant protein (MCP)-1/CCL2 -2518A>G, IL8 -251A>T, and RANTES (CCL5) -403G>A polymorphisms.

RESULTS

Genotype distributions and allele frequencies of the investigated gene polymorphisms did not significantly differ between both groups (P>0.05). Arterial hypertension, diabetes mellitus, and cigarette smoking were significantly more frequent in patients with CRVO than among control subjects (arterial hypertension: 67.0% vs. 52.2%, P<0.001; diabetes mellitus: 16.8% vs. 6.3%, P<0.001, cigarette smoking: 32.1% vs. 23.6%, P = 0.02). In a logistic regression analysis, the presence of arterial hypertension was associated with an odds ratio (OR) of 1.75 (95% confidence interval [CI], 1.26-2.44) in those with CRVO, whereas an OR of 2.52 (95% CI, 1.46-4.35) was found in those with diabetes mellitus. A history of cigarette smoking was associated with an OR of 1.57 (95% CI, 1.09 - 2.25) for CRVO.

CONCLUSIONS

Our data suggest that the investigated inflammation-related gene polymorphisms are unlikely major risk factors for CRVO.

FINANCIAL DISCLOSURE(S)

The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Lactobacillus casei modulates the inflammation-coagulation interaction in a pneumococcal pneumonia experimental model

Background

We have previously demonstrated that Lactobacillus casei CRL 431 administration improved the resistance to pneumococcal infection in a mouse model.

Methods

This study examined the effects of the oral administration of Lactobacillus casei CRL 431 (L. casei) on the activation of coagulation and fibrinolytic systems as well as their inhibitors during a Streptococcus pneumoniae infection in mice.

Results

The alveolo-capillary membrane was damaged and the coagulation system was also activated by the infection. As a consequence, we could see fibrin(ogen) deposits in lung histological slices, increased levels of thrombin-antithrombin complex (TATc) in bronchoalveolar lavage (BAL) and plasma, decrease in prothrombin activity (PT) and prolonged activated partial thromboplastin time test (APTT) values. Factor VII (FVII) and factor X (FX) were decreased in plasma, whereas fibrinogen (F) and factor VIII (FVIII) were increased. The low levels of protein C (PC) in BAL and plasma proved damage on inhibitory activity. The infected animals showed reduced fibrinolytic activity, evidenced by an increase in plasminogen activation inhibitor-1 (PAI-1) in BAL and plasma. The pathogen induced an increase of TNF-α, IL-1β and IL-6 in BAL and serum a few hours after challenge followed by a significant decrease until the end of the assayed period. IL-4 and IL-10 in BAL and serum were also augmented, especially at the end of the experiment. The animals treated with L. casei showed an improvement of alveolo-capillary membrane, lower fibrin(ogen) deposits in lung and decrease in TATc. APTT test and PT, FVII and FX activity were normalized. L. casei group showed lower F levels than control during whole experiment. In the present study no effect of L. casei on the recovery of the inhibitory activity was detected. However, L. casei was effective in reducing PAI-1 levels in BAL and in increasing anti-inflammatory ILs concentration.

Conclusion

L. casei proved effective to regulate coagulation activation and fibrinolysis inhibition during infection, leading to a decrease in fibrin deposits in lung. This protective effect of L. casei would be mediated by the induction of higher levels of IL-4 and IL-10 which could regulate the anti-inflammatory, procoagulant and antifibrinolytic effects of TNF-α, IL-1β and IL-6.

The protein C pathway and pathologic processes

Alterations in expression of protein C (PC) pathway components have been identified in patients with active inflammatory disease states. While the PC pathway plays a pivotal role in regulating coagulation and fibrinolysis, activated PC (aPC) also exhibits cytoprotective properties. For example, PC-deficient mice challenged in septic/endotoxemic models exhibit phenotypes that include hypotension, disseminated intravascular coagulation, elevated inflammatory mediators, neutrophil adhesion to the microvascular endothelium, and loss of protective endothelial and epithelial cell barriers. Further, inflammatory bowel disease has been correlated with diminished endothelial PC receptor and thrombomodulin levels in the intestinal mucosa. Downregulated expression of the cofactor, protein S, as well as PC, is also associated with ischemic stroke. Studies to elucidate further the structural elements that differentiate the various functions of PC will serve to identify novel therapeutic approaches toward regulating these and other diseases.

Circulating endotoxin and systemic immune activation in sporadic amyotrophic lateral sclerosis (sALS)

The present study reports elevated levels of endotoxin/lipopolysaccharide (LPS) concentrations in plasma from patients with sporadic amyotrophic lateral sclerosis (sALS) and Alzheimer's (AD) as compared to healthy controls. Levels of plasma LPS showed a significant positive correlation with degree of blood monocyte/macrophage activation in disease groups and was most elevated in patients with advanced sALS disease. There was a significant negative relationship between plasma LPS and levels of monocyte/macrophage IL-10 expression in sALS blood. These data suggest that systemic LPS levels and activated monocyte/macrophages may play significant roles in the pathogenesis of sALS.

Activated protein C up-regulates IL-10 and inhibits tissue factor in blood monocytes

The protective effect of recombinant activated protein C therapy in patients with severe sepsis likely reflects the ability of recombinant activated protein C to modulate multiple pathways implicated in sepsis pathophysiology. In this study, we examined the effects of recombinant activated protein C on the anti-inflammatory cytokine IL-10 and on the procoagulant molecule tissue factor (TF) in LPS-challenged blood monocytes. Treatment of LPS-stimulated monocytes with recombinant activated protein C resulted in an up-regulation of IL-10 protein production and mRNA synthesis. The up-regulation of IL-10 required the serine protease activity of recombinant activated protein C and was dependent on protease-activated receptor-1, but was independent of the endothelial protein C receptor. At the intracellular level, p38 MAPK activation was required for recombinant activated protein C-mediated up-regulation of IL-10. We further observed that incubation of LPS-stimulated monocytes with recombinant activated protein C down-regulated TF Ag and activity levels. This anticoagulant effect of recombinant activated protein C was dependent on IL-10 since neutralization of endogenously produced IL-10 abrogated the effect. In patients with severe sepsis, plasma IL-10 levels were markedly higher in those treated with recombinant activated protein C than in those who did not receive recombinant activated protein C. This study reveals novel regulatory functions of recombinant activated protein C, specifically the up-regulation of IL-10 and the inhibition of TF activity in monocytes. Our data further suggest that these activities of recombinant activated protein C are directly linked: the recombinant activated protein C-mediated up-regulation of IL-10 reduces TF in circulating monocytes.

Cancer relapse under chemotherapy: why TLR2/4 receptor agonists can help

Liver or lung metastases usually relapse under chemotherapy. Such life-threatening condition urgently needs new, systemic anticancer compounds, with original and efficient mechanisms of action. In B16 melanoma mice treated with cyclophosphamide, D'Agostini et al. [D'Agostini, C., Pica, F., Febbraro, G., Grelli, S., Chiavaroli, C., Garaci, E., 2005. Antitumour effect of OM-174 and Cyclophosphamide on murine B16 melanoma in different experimental conditions. Int. Immunopharmacol. 5, 1205-1212.] recently found that OM-174, a chemically defined Toll-like receptor(TLR)2/4 agonist, reduces tumor progression and prolongs survival. Here we review 149 articles concerning molecular mechanisms of TLR2/4 agonists, alone or in combination with chemotherapy. It appears that TLR2/4 agonists induce a well controlled tumor necrosis factor-alpha (TNF-alpha) secretion, at plasma levels known to permeabilize neoangiogenic tumor vessels to the passage of cytotoxic drugs. Moreover, TLR2/4 agonists induce inducible nitric oxide synthase (iNOS) expression, and nitric oxide is able to induce apoptosis of chemotherapy-resistant tumor cell clones. Finally, TLR2/4-stimulation activates dendritic cell traffic and its associated tumor-specific, cytotoxic T-cell responses. Therefore, parenteral TLR2/4 agonists seem promising molecules to prolong survival in cancer patients who relapse under chemotherapy.

Coagulation interventions in experimental human endotoxemia

Recognition of the link between coagulation activation and inflammation has led to the hypothesis that anticoagulants may be effective in the treatment of septic patients by altering the inflammatory response. However, only limited methodologies exist that can be used in human volunteers to mimic the physiologic alterations observed in critically ill patients. The human endotoxemia model represents a model of inflammation-induced tissue factor triggered coagulation activation. As it permits elucidation of a key player in this proinflammatory and procoagulant response, it serves as a useful tool to investigate novel therapeutics in a standardized setting. The aim of this review is to focus on coagulation interventions in the human endotoxemia model.

Vagus nerve stimulation inhibits activation of coagulation and fibrinolysis during endotoxemia in rats

BACKGROUND

Sepsis and endotoxemia are associated with concurrent activation of inflammation and the hemostatic mechanism, which both contribute to organ dysfunction and death. Electrical vagus nerve stimulation (VNS) has been found to inhibit tumor necrosis factor (TNF)-alpha release during endotoxemia in rodents.

OBJECTIVE

To determine the effect of VNS on activation of coagulation and fibrinolysis.

METHODS

Rats received a sublethal i.v. dose of lipopolysaccharide (LPS) after electrical VNS or sham stimulation. Activation of coagulation and fibrinolysis, as well as cytokine release, was measured before LPS injection and 2, 4 and 6 h thereafter.

RESULTS

LPS induced activation of the coagulation system (increases in the plasma concentrations of thrombin-antithrombin complexes and D-dimer, and a decrease in antithrombin) and biphasic changes in the fibrinolytic system [early rises of plasminogen activator activity and tissue-type plasminogen activator, followed by a delayed increase in plasminogen activator inhibitor type 1 (PAI-1)]. VNS strongly inhibited all LPS-induced procoagulant responses and more modestly attenuated the fibrinolytic response. In addition, VNS attenuated the LPS-induced increases in plasma and splenic concentrations of the proinflammatory cytokines TNF-alpha and interleukin-6 (IL-6), while not influencing the release of the anti-inflammatory cytokine IL-10.

CONCLUSION

These data illustrate a thus far unrecognized effect of VNS and suggest that the cholinergic anti-inflammatory pathway not only impacts on inflammation but also on the coagulant-anticoagulant balance.

Long-term incubation with IL-4 and IL-10 oppositely modifies procoagulant activity of monocytes and modulates the surface expression of tissue factor and tissue factor pathway inhibitor

Monocytes can be induced to express both tissue factor (TF) and its inhibitor, TF pathway inhibitor-1 (TFPI-1). A short incubation (<6 h) with interleukin (IL)-4 and IL-10, two potent deactivators of monocyte functions, has been shown to modulate the synthesis and expression of TF by monocytes activated by lipopolysaccharide, but the consequences of longer incubations (up to 96 h) on both TF and TFPI-1 are unknown. The results of this study showed that adherent monocytes in culture spontaneously expressed TF and TFPI and that prolonged incubation with IL-10 induced a time- and dose-dependent decrease of monocyte TF synthesis, and an accumulation of TF/TFPI-1 complexes at the moncyte surface, suggesting a decreased clearance of these complexes. In contrast, IL-4 induced a time- and dose-dependent increase in TF synthesis, which remained intracytoplasmic, as shown by confocal microscopy. Surprisingly, TF:antigen (Ag) was decreased at the monocyte surface, but the procoagulant activity (PCA) of IL-4-treated monocytes was increased, as a result of more pronounced decrease of TFPI-1:Ag expression than that of TF. In conclusion, prolonged incubation with IL-4 and IL-10 oppositely modified PCA of cultured monocytes, and altered TF and TFPI trafficking and clearance. These data explain the respective deleterious or benefit effects of IL-4 or IL-10 in atherothrombosis.

Interleukin-10 suppresses tissue factor expression in lipopolysaccharide-stimulated macrophages via inhibition of Egr-1 and a serum response element/MEK-ERK1/2 pathway

Atherosclerosis is considered to be an inflammatory disease. Tissue factor (TF), a prothrombotic molecule expressed by various cell types within atherosclerotic plaques, is thought to play an essential role in thrombus formation after atherosclerotic plaque rupture. Recent studies suggest that the antiinflammatory cytokine interleukin-10 (IL-10) has many antiatherosclerotic properties. Therefore, the effects of IL-10 on TF expression in response to inflammation were investigated. Mouse macrophages were stimulated with lipopolysaccharide (LPS) in the presence or absence of IL-10. Pretreatment with IL-10 resulted in a 50% decrease in TF mRNA expression and TF promoter activity. Binding of early growth response gene-1 (Egr-1) to the consensus DNA sequence, a key transcriptional activator of TF expression in response to inflammation, and the expression of Egr-1 mRNA were also inhibited by IL-10. This inhibition was independent of the induction of suppressor of cytokine signaling protein-3 by IL-10. Macrophages that had been transfected with luciferase reporter constructs containing the murine Egr-1 5'-flanking sequence exhibited reduced reporter gene activity in response to LPS stimulation with IL-10 pretreatment. Studies with deletion constructs of the Egr-1 promoter identified the proximal serum response element SRE3 as a potential regulatory site for the IL-10 mediated suppression of Egr-1 expression. Furthermore, activation of the upstream signal-transduction elements, such as mitogen-activated protein kinase kinase (MEK) 1/2, extracellular signal-regulated kinase 1/2, and Elk-1 were also inhibited by IL-10 pretreatment. Taken together, these results demonstrate a pathway for the IL-10 mediated inhibition of TF expression during inflammation and may explain the antiatherosclerotic effects of IL-10.

Increased resistance of LFA-1-deficient mice to lipopolysaccharide-induced shock/liver injury in the presence of TNF-alpha and IL-12 is mediated by IL-10: a novel role for LFA-1 in the regulation of the proinflammatory and anti-inflammatory cytokine balance

Challenge with low doses of LPS together with D-galactosamine causes severe liver injury, resulting in lethal shock (low dose LPS-induced shock). We examined the role of LFA-1 in low dose LPS-induced shock. LFA-1(-/-) mice were more resistant to low dose LPS-induced shock/liver injury than their heterozygous littermates, although serum levels of TNF-alpha and IL-12 were higher in these mice. C57BL/6 mice were not rescued from lethal effects of LPS by depletion of NK1(+) cells, granulocytes, or macrophages, and susceptibility of NKT cell-deficient mice was comparable to that of controls. High numbers of platelets were detected in the liver of LFA-1(+/-) mice after low dose LPS challenge, whereas liver accumulation of platelets was only marginal in LFA-1(-/-) mice. Following low dose LPS challenge, serum levels of IL-10 were higher in LFA-1(-/-) mice than in LFA-1(+/-) mice, and susceptibility to low dose LPS-induced shock as well as platelet accumulation in the liver of LFA-1(-/-) mice were markedly increased by IL-10 neutralization. Serum levels of IL-10 in LFA-1(+/-) mice were only marginally affected by macrophage depletion. However, in LFA-1(-/-) mice macrophage depletion markedly reduced serum levels of IL-10, and as a corollary, susceptibility of LFA-1(-/-) mice to low dose LPS-induced shock was markedly elevated despite the fact that TNF-alpha levels were also diminished. We conclude that LFA-1 participates in LPS-induced lethal shock/liver injury by regulating IL-10 secretion from macrophages and that IL-10 plays a decisive role in resistance to shock/liver injury. Our data point to a novel role of LFA-1 in control of the proinflammatory/anti-inflammatory cytokine network.

Cellular IL-10 is more effective than viral IL-10 in decreasing venous thrombosis

BACKGROUND

Systemic administration of cellular interleukin-10 (cIL-10) and gene transfection of viral interleukin-10 (vIL-10) at thrombus induction decreases vein wall inflammation. Only cIL-10, despite sharing an 84% amino acid sequence homology with vIL-10, decreases thrombosis through mechanisms yet to be determined.

METHODS

C57BL/6 mice (Mus musculus, n99) were studied. Inferior vena caval thrombosis was created by inferior vena caval ligation and the animals were sacrificed and evaluated at days 2 and 6 after ligation. At thrombus induction groups received intravenous 0.25 microg of cIL-10, 0.25 microg of vIL-10, or saline (untreated controls). Evaluations included thrombus mass and vein wall leukocyte counts, protein levels, and reverse-transcription polymerase chain reaction mRNA levels of P- and E-selectin, monocyte chemotactic protein-1, and IL-10. Groups were compared by analysis of variance and t tests.

RESULTS

Less thrombus was noted at both days 2 and 6 in animals treated with cIL-10. At day 2 only, vein wall leukocyte counts revealed a significant decrease in neutrophils in cIL-10 animals versus controls, with no significant differences for vIL-10 animals. In cIL-10-treated animals, P-selectin protein levels were decreased at day 6, along with a decreased thrombus mass, without significant differences in E-selectin, monocyte chemotactic protein-1, or IL-10 protein levels. vIL-10 treated animals showed increased E-selectin mRNA and thrombus mass versus controls on day 6.

CONCLUSIONS

cIL-10 is more antithrombotic/anti-inflammatory than vIL-10. This may be the result of cIL-10 decreasing P-selectin protein expression and vIL-10 increasing E-selectin mRNA levels.

[Interleukin-10 and coronary disease]

Understanding of the pathophysiology of atherosclerosis has changed markedly over the past few decades. It is now widely accepted that inflammation plays a fundamental role in the genesis and development of atherosclerosis. Inflammatory mechanisms also appear to determine clinical presentation and disease outcome. Atherosclerotic lesions have high concentrations of inflammatory cells (T lymphocytes and activated macrophages) as well as an abundance of pro-inflammatory cytokines [interleukin (IL)-1, IL-6, IL-8, interferon-gamma, tumor necrosis factor-alpha, etc.] that modulate local inflammatory responses. These may also alter plaque stability and facilitate the development of acute cardiovascular events. The role of anti-inflammatory cytokines in this context remains to be studied. IL-10 is an anti-inflammatory cytokine synthesised by T-lymphocytes and macrophages and has other anti-inflammatory effects. IL-10 expression within human atherosclerotic plaques has been demonstrated and animal experiments have shown that low levels of IL-10 lead to the development of extensive and unstable atherosclerotic lesions. Currently available evidence suggests a potential protective role for IL-10 in atherosclerosis. This new perspective on coronary disease as a chronic inflammatory process may open new avenues for the management of ischemic heart disease.

The role of tissue factor in renal ischemic reperfusion injury of the rat

BACKGROUND

Tissue factor (TF) is a membrane-bound glycoprotein that is the primary cellular initiator of the blood clotting cascade and its expression is induced on macrophages and endothelial cells during the inflammatory or immune response. Tissue factor pathway inhibitor (TFPI) regulates the extrinsic pathway of blood coagulation through its ability to inhibit tissue factor activity. We studied the role of TF in the kidney following warm ischemic reperfusion and studied the effect of TFPI in vivo.

MATERIALS AND METHODS

After laparotomy of Lewis rats, the right kidney was harvested and left renal artery and vein were clamped. The kidney was reperfused after 60, 120, and 180 min of ischemia. Rats were sacrificed at 0, 1.5, 5, 12, and 24 h after reperfusion with or without TFPI treatment, and the kidney was harvested. Blood samples were collected at 0, 5, 12, and 24 h after reperfusion from the abdominal aorta. Blood urea nitrogen and kalium were monitored. TF expression was also studied by immunohistochemical staining with a monoclonal antibody (HTF-K108).

RESULTS

Histologically, the necroses of the tubular epithelial cells were observed 1.5 h after reperfusion. Immunohistochemically, TF staining was positive on the glomerular endothelial cells and stimulated monocytes but negative on the tubular epithelial cells. The necrotic area extended and encompassed almost all of the ischemic kidney by 12 h after reperfusion. TF was stained on the glomerular base membrane, the glomerular endothelial cells, and the stimulated monocytes but was not evident on the necrotic tubular epithelial cells. Fibrinogen was also observed in the glomerular endothelial cells at 5-12 h after reperfusion, while it was slight in normal tissue. With TFPI treatment, the necrotic area was narrow and TF was slightly stained on the endothelial cells.

CONCLUSIONS

These results suggest that TF plays an important role in the development of renal injury after ischemia and reperfusion. The microcirculatory incompetence due to microthrombus might cause the formation and development of the necrosis. These results also suggest that TFPI plays a key role in modulating tissue factor-dependent blood coagulation, therefore TFPI is a strong medication for prevention of ischemic reperfusion injury.

Staging of the pathophysiologic responses of the primate microvasculature to Escherichia coli and endotoxin: examination of the elements of the compensated response and their links to the corresponding uncompensated lethal variants

OBJECTIVE

Review of primate studies of Escherichia coli sepsis and endotoxemia with a reexamination of the rationale for diagnosis and treatment of these multistage disorders.

SETTING

Animal research and intensive care units in a university medical school.

SUBJECTS

Cyanocephalus baboons (E. coli) and normal human subjects (endotoxin).

INTERVENTIONS

Baboon studies: anti-tissue factor, protein C, endothelial protein C receptor, and anti-tumor necrosis factor antibodies, and active site inhibited factor recombinant VIIa and factor Xa.

RESULTS AND CONCLUSIONS

This review concerns the primate microvascular endothelial response to inflammatory and hemostatic stress. Studies of the impact of inflammatory and hemostatic stress on this microvasculature have fallen into four categories. First, studies of pure hemostatic stress using factor Xa phospholipid vesicles showed that blockade of protein C as well as protein C plus tissue plasminogen activator produced a severe but transient consumptive and a lethal thrombotic coagulopathy, respectively. These studies showed that the protein C and fibrinolytic systems can work in tandem to regulate even a severe response if the endothelium is not rendered dysfunctional by metabolic or inflammatory factors. Second, studies of compensated (nonlethal) inflammatory stress using E. coli or endotoxin in baboon and human subjects showed that even under minimal stress in which there is no evidence of overt disseminated intravascular coagulation, injury of the endothelium and activation of neutrophils and hemostatic factors are closely associated. This showed that molecular markers of hemostatic activity could be used to detect microvascular endothelial stress (nonovert disseminated intravascular coagulation) in patients who are compensated but at risk. These studies also showed that the compensated response to inflammatory stress could exhibit two stages, each with its unique inflammatory and hemostatic response signature. The first is driven by vasoactive peptides, cytokines, and thrombin, followed 12 to 14 hrs later by a second stage driven by C-reactive protein/complement complexes, tissue factor, and plasminogen activator inhibitor 1 secondary to oxidative stress after reperfusion. Third, studies of uncompensated (lethal) inflammatory stress using E. coli showed that irreversible thrombosis of the microvasculature was not a link in the lethal chain of events even though inhibition of components of the protein C network (protein C and endothelial protein C receptor) converted compensated responses to sublethal E. coli into uncompensated lethal responses. Fourth, these studies also showed that there were variants of the lethal response ranging from capillary leak and shock to recurrent sustained inflammatory disorders. We believe that each of these variants arises from their sublethal counterparts, depending on underlying or modulating host factors operating at the time of challenge. Such underlying conditions range from preexisting microvascular ischemia, reperfusion, and oxidative stress to alteration or reprogramming of monocyte/macrophage responses (tolerance to hyperresponsiveness). Characterization of these underlying conditions in patients who are at risk should aid in identifying and optimizing management of these variants.

Interleukin-10 regulates the tissue factor activity of monocytes in an in vitro model of bacterial endocarditis

Monocytes are important effector cells in the pathogenesis of bacterial endocarditis since they provide the tissue factor that activates the coagulation system and maintains established vegetations. Monocytes secrete cytokines that can modulate monocyte tissue factor activity (TFA), thereby affecting the formation and maintenance of vegetations. In this study, we show that monocytes cultured for 4 h on a Streptococcus sanguis-infected fibrin matrix mimicking the in vivo vegetational surface express high levels of TFA. This was accompanied by secretion of the proinflammatory cytokines tumor necrosis factor alpha (TNF-alpha), interleukin-1 alpha (IL-1 alpha), and IL-1 beta. After a 24-h incubation period the anti-inflammatory cytokine IL-10 could also be detected. Our data show that, whereas TNF-alpha and IL-1 have a minor role in the induction of TFA by monocytes cultured on a fibrin matrix, TNF-alpha but not IL-1 plays an important role in the induction of IL-10 by these cells. In turn, our data show that IL-10 is an important factor in the downregulation of monocyte TFA. In summary, we conclude that IL-10 is an important factor in the control of monocyte TFA in endocardial vegetations.

Interleukin 10 regulates cellular responses in monocyte/endothelial cell co-cultures

Adhesive interactions between monocytes and vascular endothelial cells increase the expression of the inflammatory genes, tissue factor (TF) and E-selectin, thus contributing to the inflammatory process. In this study, we have shown that these responses could be regulated by the immunomodulatory cytokine interleukin 10 (IL-10). IL-10 reduced TF generation in monocyte/endothelium co-cultures (64. 3 +/- 3.3% reduction, P < 0.01, n = 4) by acting directly on monocytes, whereas IL-4 inhibited TF expression in both monocytes and endothelium. Similarly, IL-10 reduced the induction of endothelial E-selectin by monocytes (100% reduction at 21 h), but had no effect on cytokine-induced E-selectin expression. IL-10 itself was not able to induce E-selectin protein or mRNA in endothelial cells. IL-10 mRNA was detected in monocytes after 6 h co-culture with endothelial cells, and was sustained for up to 30 h. Finally, IL-10 significantly reduced the adhesion of monocytes to endothelium (45% reduction), which may account in part for the inhibitory actions of IL-10. We conclude that IL-10 has an anti-inflammatory effect on monocyte/endothelium interactions, and may itself be produced as a result of such interactions.

Interleukin-10 inhibits intimal hyperplasia after angioplasty or stent implantation in hypercholesterolemic rabbits

BACKGROUND

Intimal hyperplasia after stent implantation is the main cause of in-stent restenosis. Activated monocytes play a key role in intimal growth. The anti-inflammatory cytokine interleukin-10 (IL-10) is a potent monocyte deactivator, endogenously produced in the atherosclerotic plaque. We tested the hypothesis that exogenous IL-10 may limit postangioplasty intimal hyperplasia after balloon angioplasty or stenting.

METHODS AND RESULTS

Hypercholesterolemic rabbits were treated with recombinant human IL-10 (rhuIL-10) for 3 days after balloon angioplasty or 28 days after stent implantation. High IL-10 serum levels and intense deactivation of circulating monocytic cells, assessed by inhibition of IL-1beta release by lipopolysaccharide-stimulated whole blood, were detected for at least 8 hours after rhuIL-10 intravenous injection (ELISA). Morphometric analyses, performed 28 days after injury, indicated that rhuIL-10 reduced intimal growth by approximately 50% after balloon angioplasty or stenting, resulting in more preserved lumen in stented arteries. Moreover, rhuIL-10 reduced macrophage infiltration by 67% and proliferative activity by 81% in the intima and the media. No toxic effect was detected except minor changes in blood cell count.

CONCLUSIONS

The anti-inflammatory cytokine rhuIL-10 reduces postinjury intimal hyperplasia. The potent attenuation of in-stent intimal growth by rhuIL-10 and its favorable toxicity profile suggest that rhuIL-10 may be useful in the prevention of in-stent restenosis.

Expression of tissue factor in hepatic ischemic-reperfusion injury of the rat

BACKGROUND

Tissue factor (TF) is a membranous protein normally present on the surface of the fibroblasts and smooth muscle cells of vessels. TF is an initiation factor for blood coagulation, and its expression is induced on macrophages and endothelial cells during the inflammatory or immune response. We studied the significance of TF expression in warm ischemic-reperfusion injury of the liver using a rat model.

METHODS

Following laparotomy of Lewis rats, the branches of the hepatic artery and portal vein leading to the median, left, and caudate lobes of the liver were clamped for 2 hr. The liver was reperfused after 120 min of ischemia. Rats were killed at 0, 1, 3, 5, 8, and 12 hr after reperfusion, and liver tissues were harvested. TF activity was measured by the chromophilic substrate S-2222. TF expression was studied by immunohistochemical staining with the monoclonal antibody HTF-K108.

RESULTS

TF activity in the blood showed a peak at 3 hr after reperfusion (8.9+/-0.5 U/L), then decreased and returned to the normal level by 12 hr (0.9+/-0.3 U/L). TF activity in ischemic liver tissue increased gradually over 12 hr after reperfusion (1223+/-275 U/g dry weight before ischemia and 2545+/-284 U/g weight at 12 hr after reperfusion). Histologically spotty necroses were observed in the liver tissue 5 hr after reperfusion. The necrotic area extended and encompassed almost all of the ischemic liver by 12 hr after reperfusion. Histochemically, TF staining was negative on the hepatocytes and slightly positive on sinusoid cells of the normal liver. On the other hand, TF was strongly stained, especially on the hypertrophic monocytic cells accumulating at the site of the necrosis, but staining was not evident on the necrotic hepatocytes. A slight degree of TF staining was observed on the alveolar epithelium of the lung, irrespective of liver ischemia and reperfusion.

CONCLUSION

These results demonstrate that TF plays an important role in the development of the hepatic ischemic-reperfusion injury, and the subsequent microcirculatory incompetence might cause the formation of microthrombus and the development of necrosis.

IL-10 Regulates Thrombus-Induced Vein Wall Inflammation and Thrombosis

Vein wall inflammation associated with venous thrombosis is mediated by an imbalance in proinflammatory as compared with antiinflammatory molecules. We hypothesize that IL-10 is an important antiinflammatory cytokine that influences vein wall inflammation and thrombus propagation during venous thrombosis. To test this hypothesis a model of inferior vena caval thrombosis was used. Studies were performed at sacrifice 2 days after thrombus induction and included leukocyte morphometrics, myeloperoxidase activity, vein wall permeability, thrombus weight, and IL-10 ELISA analysis from the vein wall. IL-10 was elevated in the vein wall during venous thrombosis. Neutralization of IL-10 increased inflammation, while supplementation with rIL-10 demonstrated a dose- and time-dependent decrease in inflammation. Interestingly, a low 2.5-μg rIL-10 dose given at time of initiation of thrombosis most significantly decreased inflammation. Thrombus weight was importantly diminished by reconstitution of IL-10. These studies support an important role for IL-10 in the regulation of thrombus-associated inflammation and thrombosis and suggest that IL-10 could be used as a therapeutic agent in the treatment of venous thrombosis.

IL-10 inhibits LPS-induced human monocyte tissue factor expression in whole blood

Interleukin 4 (IL-4), IL-10 and IL-13 are all known to modulate several proinflammatory functions in human monocytes. They have also previously been shown to down-regulate lipopolysaccharide (LPS)-induced tissue factor (TF) expression in isolated cultured monocytes. In this study we investigated the effect of these three cytokines on the induction of monocytic TF in a whole blood environment at three levels: mRNA quantitation, surface antigen expression and procoagulant activity. We showed that IL-10 attenuated LPS-induced monocyte TF expression and activity in whole blood in a concentration-dependent manner, both when added to the blood prior to LPS and, although to a lesser extent, when added up to 1 h subsequent to LPS challenge. Maximum inhibition occurred at 5 ng/ml of IL-10 when the cytokine was added before LPS. IL-4 and IL-13, however, did not exhibit any inhibitory effect in the whole blood environment, contrary to the reported findings in cell culture experiments. Our results confirm the potential of IL-10 as an anti-inflammatory, TF-preventing drug, whereas the effects of IL-4 and IL-13 on monocytes in whole blood seem more complex, and require further investigation.

Monocyte B7 and Sialyl Lewis X modulates the efficacy of IL-10 down-regulation of LPS-induced monocyte tissue factor in whole blood

Recent studies have investigated the use of anti-inflammatory cytokine, interleukin 10 (IL-10) to control the development of disseminated intravascular coagulation (DIC) in sepsis by down-regulation of monocyte tissue factor (MTF) induced by lipopolysaccharide (LPS) in the initial phase of the disease. In vitro and in vivo human studies have shown that a minimal (<1 h) delay in IL-10 treatment significantly reduces the cytokines ability to inhibit LPS-induced MTF expression and the end products of coagulation. In this whole blood in vitro study we investigated the role of lymphocyte and platelet interactions with monocytes to up-regulate MTF expression in the presence of IL-10 in the initial phase of exposure to LPS. Individual blockade of monocyte B7 or platelet P-selectin significantly (35%) reduced MTF expression (P<0.05). IL-10 showed a dose-dependent inhibition of LPS (0.1 microg/ml) induced MTF expression, with 56% inhibition at 1 ng/ml, maximizing at 5 ng/ml IL-10 (75%; P<0.05). Simultaneous exposure to LPS and IL-10 (1 ng/ml) or addition of IL-10 1 h after LPS, with individual B7 and P-selectin blockade significantly enhanced the inhibition of MTF expression by IL-10 (P<0.05). We conclude that the efficacy of IL-10 to control DIC could be enhanced by a simultaneous B7 and P-selectin blockade.

Regulation of the uPAR/uPA system expressed on monocytes by the deactivating cytokines, IL-4, IL-10 and IL-13: consequences on cell adhesion to vitronectin and fibrinogen

Urokinase (uPA) and its receptor (uPAR) have been proposed to be involved in monocyte migration by inducing degradation of matrix proteins. In addition, uPAR is also implicated in cell adhesion to the vascular wall. The adhesive function of uPAR depends on a direct interaction with vitronectin which is increased by uPA and by modification of cell surface integrin (such as CD11b-CD18) when associated to uPAR. In this study we analysed the role of three deactivating cytokines, IL-4, IL-10 and IL-13, on the surface expression of uPA, uPAR and CD11b by monocytes and their consequences on monocyte adhesion to immobilized fibrinogen and vitronectin. IL-10 induced a decrease in uPA and CD11b after 18 h incubation and a delayed decrease in uPAR which was only significant after 48 h incubation. These results may explain the decrease in monocyte adhesion, which was observed after an 18 h incubation with IL-10, on immobilized vitronectin and fibrinogen. In contrast, IL-4 and IL-13 induced a decrease in uPAR after 18 h and a significant increase in uPA both in the cell lysates and at the cell surface, as well as an increase in cell surface associated CD11b. These cytokines did not modify cell adhesiveness to vitronectin or fibrinogen despite the increase in CD11b-CD18. This could be due to the decrease in uPAR because CD11b-CD18/uPAR forms a cell adhesion complex. In addition, the increase in uPA induced by IL-4 could counterbalance the direct interaction of uPAR with vitronectin. The increase in uPA suggests that IL-4 and IL-13 could induce plaque fissuring by monocytes, whereas IL-10 may induce protection against matrix protein degradation by decreasing uPA.

Acidic and basic fibroblast growth factors suppress transcriptional activation of tissue factor and other inflammatory genes in endothelial cells

Tissue factor (TF) is a transmembrane receptor that serves as a cofactor for factor VIIa and initiates the extrinsic pathway of blood coagulation. Under normal physiological conditions, TF is expressed in extravascular and perivascular cells but not in vascular endothelial cells and monocytes. TF can be induced in these cells by inflammatory regulators and other stimulators, such as LPS, thrombin, oxidized lipoproteins, and certain growth factors. An earlier study showed that growing primary cultures of human umbilical vein endothelial cells (HUVECs) with endothelial cell growth supplement (ECGS) and heparin had impaired the ability of monolayers to express surface membrane TF activity after perturbation. The mechanism by which ECGS suppressed TF activity was not known. In the present study, we investigated the effect of recombinant acidic and basic fibroblast growth factors (aFGF and bFGF) on the induction of TF in a HUVEC cell line and a fibroblast cell line. Both aFGF and bFGF suppressed the phorbol myristate acetate-induced expression of TF in endothelial cells but not the serum-induced expression of TF in fibroblast cells. Diminished expression of the cell surface TF activity observed in endothelial cells grown with aFGF or bFGF was due to the accumulation of a lower number of TF mRNA transcripts. TF mRNA stability was not altered in HUVECs grown with aFGF or bFGF. Nuclear run-on experiments revealed that the transcription of TF and several other genes that play an important role in inflammation and angiogenesis was reduced in the endothelial cells that were cultured with aFGF or bFGF. The diminished expression of TF may be part of a generalized response of endothelial cells to FGF that facilitates migration of endothelial cells during angiogenesis.

Interleukin-10 Inhibits Activation of Coagulation and Fibrinolysis During Human Endotoxemia

Interleukin-10 (IL-10) has been found to inhibit lipopolysaccharide (LPS)-induced tissue factor expression by monocytes in vitro. To determine the effects of IL-10 on LPS-induced activation of the hemostatic mechanisms in vivo, we performed a placebo-controlled, cross-over study of human endotoxemia. Two groups of eight volunteers were challenged with LPS (4 ng/kg) on two occasions: once in conjunction with placebo, and once with recombinant human IL-10 (rhIL-10; 25 μg/kg). In group 1, placebo or rhIL-10 was given 2 minutes before LPS challenge, group 2 received placebo or rhIL-10 1 hour after LPS administration. Pretreatment with rhIL-10 reduced both LPS-induced activation of the fibrinolytic system (plasma concentrations of tissue type plasminogen activator, plasmin-α2–antiplasmin complexes, and D-dimer), and inhibition of fibrinolysis (plasma levels of plasminogen activator inhibitor 1), whereas posttreatment only inhibited the latter response. Both IL-10 pre- and posttreatment attenuated activation of the coagulation system (plasma levels of prothrombin fragment F1 + 2 and thrombin–antithrombin complexes). These results indicate that rhIL-10, besides its well-described inhibitory effects on cytokine release, potently modulates the fibrinolytic system and inhibits the coagulant responses during endotoxemia.

Net inflammatory capacity of human septic shock plasma evaluated by a monocyte-based target cell assay: identification of interleukin-10 as a major functional deactivator of human monocytes

We have developed a functional assay to study the inflammatory capacity of plasma collected from patients with severe gram-negative septic shock. In this assay, elutriation-purified, cryo-preserved human monocytes from one healthy donor are combined with plasma from patients with severe persistent septic shock for 5 h. Subsequently, the plasma is removed, medium added, and procoagulant activity (PCA) and secretion of tumor necrosis factor alpha (TNF-alpha) and interleukin 6 (IL-6) measured after 18-h incubation. Plasma from 10 patients (6 died) infected with Neisseria meningitidis previously shown to contain high levels of native lipopolysaccharide (LPS) (median 2,700 pg/ml), TNF-alpha, IL-6, IL-8, and complement activation products, had a low net spontaneous inflammatory capacity on the monocytes. The median levels of PCA, TNF-alpha, and IL-6 were 5, 0, and 4%, respectively, of the monocyte activities induced by normal plasma boosted with purified N. meningitidis (Nm)-LPS (2,500 pg/ml; net LPS-boosted capacity, 100%). The levels of PCA, TNF-alpha, and IL-6 obtained with plasma from shock patients were not different from those induced by plasma from 10 meningococcal patients without shock or with plasma from healthy persons. Boosting shock plasma with 2,500 pg/ml Nm-LPS had little effect on the monocyte activities since the median values of PCA, TNF-alpha, and IL-6 revealed a minimal increase from 5, 0, and 4% to 9, 2, and 6%, respectively. The shock plasmas revealed a strong LPS-inhibitory capacity that was largely absent in plasmas from 10 meningococcal patients without shock since the median levels of PCA, TNF-alpha, and IL-6 increased from 5, 0, and 0% to 135, 51, and 73%, respectively, after boosting with 2,500 pg/ml Nm-LPS. The LPS-inhibitory capacity was closely associated with the levels of IL-10. The median levels of IL-10 were 19,000 pg/ml in nine shock patients vs. 22 pg/ml in nine nonshock patients with systemic meningococcal disease. Removal of native IL-10 by immunoprecipitation restored the capacity of plasmas to induce monocyte activation either by native LPS or by boosting with Nm-LPS. IL-4 and TGF-beta were not detected in shock plasmas. In 24 patients with detectable meningococcal LPS ( > 10 pg/ml, 0.1 endotoxin units/ml), the levels of IL-10 were correlated to the levels of LPS (r = 0.79, P < 0.001). IL-10 declined from initiation of antibiotic therapy and paralleled the levels of native LPS. Decreasing levels of IL-10 in serially collected shock plasmas were directly related to increasing monocyte responsiveness after Nm-LPS boosting. These results suggest that IL-10 plays a major role in containing activation of monocytes and possibly other LPS-responsive cells during overwhelming meningococcemia.

Interleukin-10 and pentoxifylline inhibit C-reactive protein-induced tissue factor gene expression in peripheral human blood monocytes

Fibrin deposition is an integral feature of the inflammatory response. In response to C-reactive protein (CRP), an acute-phase reactant, blood monocytes synthesize and express tissue factor (TF), the main initiator of blood coagulation. We report the inhibitory effect of interleukin 10 (IL-10) and that of pentoxifylline, a methyl xanthine derivative, on monocyte expression of TF activity, TF protein and TF mRNA in response to CRP. These agents may be of use in diseases where a TF-induced prothrombotic state is detrimental.

Transforming growth factor-beta and interleukin-10, but not interleukin-4, down-regulate procoagulant activity and tissue factor expression in human monocyte-derived macrophages

The effect of IL-4, IL-10, and TGF-beta on expression of procoagulant activity (PCA) and of surface-associated tissue factor (TF) by human monocyte-derived macrophages was determined. Monocytes were allowed to mature to macrophages in teflon bags, and were primed either in suspension cultures, or after subculturing in microtiter plates. PCA was determined in PBS-stimulated cells (constitutive PCA) or after stimulation with LPS for 6 hr. TGF-beta significantly reduced constitutive and LPS-induced PCA. This effect was associated with a reduction in surface-expressed TF, but was not correlated with TNF-alpha production in LPS-stimulated cells. The TGF-beta effect was seen both in suspension cultures and in adherent cultures. IL-10 strongly down-regulated LPS-induced PCA, an effect closely correlated with TNF production. It had a weaker, albeit significant effect on constitutive PCA, when tested on suspended cells, and PCA down-regulation was associated with reduction in TF surface expression. IL-4 reduced neither constitutive nor induced PCA in macrophages, and had little effect on TF surface expression, although it strongly down-regulated CD14 expression. Also in monocytes, IL-4 influenced TF expression to a lesser degree than IL-10 and TGF-beta. In the monocytoid cell line, THP-1, PCA/TF was down-regulated preferentially by TGF-beta. Our findings point to a complex cytokine-mediated regulation of PCA at the level of TF expression and possibly at additional levels.