Interactions between neutrophils and endothelial cells

Oxygen-Derived Free Radicals as Mediators of Varicose Vein Wall Damage

Varicose saphenous vein segments, segments of those veins with thrombophlebitis, and segments of normal veins obtained during operation on 23 patients were studied to define the pattern of pro-oxidative and antioxidative systems in these tissues. In segments of varicose veins (VV) the activity of superoxide dismutase (SOD) was significantly decreased as compared with normal veins: 7.8 ±2.9 vs 13.5 ±4.3 U/mg of protein (P < 0.05), but it was almost unchanged in the segments of W with thrombophlebitis. The activity of glutathione reductase (GSH-R) in all studied segments was similar and amounted to about 12.0 IU.

The content of free sulfhydryl (SH) groups, the concentration of ascorbic acid, and thiobarbituric acid-reactive substances (TBA-RS) in segments of VV were significantly decreased by 40%, 48%, and 47%, respectively (P < 0.05) as compared with segments of normal veins. The values of ascorbic acid and TBA-RS in the segments of W with thrombophlebitis were increased by 13% and 16%, respectively, as compared with segments of normal veins. Decreased activities of SOD and reduced levels of free SH-groups and of ascorbic acid concentration in W may indicate impaired antioxidant mechanisms in this tissue.

Microcirculatory alterations in shock states

Functional components of the microcirculation provide oxygen and nutrients and remove waste products from the tissue beds of the body's organs. Shock states overwhelmingly stress functional capacity of the microcirculation, resulting in microcirculatory failure. In septic shock, inflammatory mediators contribute to hemodynamic instability. In nonseptic shock states, the microcirculation is better able to compensate for alterations in vascular resistance, cardiac output, and blood pressure. Therefore, global hemodynamic and oxygen delivery parameters are appropriate for assessing, monitoring, and guiding therapy in hypovolemic and cardiogenic shock but, alone, are inadequate for septic shock.

Study on the action of resistin-induced human umbilical vein endothelial cell dysfunction

The aim of this paper was to investigate the effects of resistin on human umbilical vein endothelial cells (HUVECs), and to explore its role and mechanism of action in atherosclerosis. HUVECs were incubated with recombinant human resistin (0, 50, 100 ng/mL) for 24 h. ICAM-1, VCAM-1 and reactive oxygen species (ROS) were assayed by flow cytometer. ET-1, eNOS and iNOS mRNA expression were measured by semi-quantitative RT-PCR. Incubation of HUVECs with resistin resulted in an increase in ICAM-1 expression and ET-1 mRNA expression. However, resistin had no effect on VCAM-1 expression and ROS release. eNOS and iNOS mRNA expression were not altered by resistin stimulation. Adipokine resistin exerted a direct effect in promoting HUVEC dysfunction by promoting ICAM-1 and ET-1 expression. These data suggest that adipocyte-endothelium cross-talk might play an important role in the pathogenesis of cardiovascular disease in diabetes mellitus.

Resolvin D2 prevents secondary thrombosis and necrosis in a mouse burn wound model

Deep partial thickness burns are subject to delayed necrosis of initially viable tissues surrounding the primary zone of thermally induced coagulation, which results in an expansion of the burn wound, both in area and depth, within 48 hours postburn. Neutrophil sequestration and activation leading to microvascular damage is thought to mediate this secondary tissue damage. Resolvins, a class of endogenous mediators derived from omega-3 polyunsaturated fatty acids, have been shown to regulate the resolution of inflammation. We hypothesized that exogenous resolvins could mitigate the deleterious impact of the inflammatory response in burn wounds. Using two different mouse burn injury models involving significant partial thickness injuries, we found that a systemically administered single dose of resolvin D2 (RvD2) as low as 25 pg/g bw given within an interval of up to 4 hours postburn effectively prevented thrombosis of the deep dermal vascular network and subsequent dermal necrosis. By preserving the microvascular network, RvD2 enhanced neutrophil access to the dermis, but prevented neutrophil-mediated damage through other anti-inflammatory actions, including inhibition of tumor necrosis factor-α, interleukin-1β, and neutrophil platelet-endothelial cell adhesion molecule-1. In a clinical context, RvD2 may be therapeutically useful by reducing the need for surgical debridement and the area requiring skin grafting.

Prognosis in the patients with prolonged extracorporeal membrane oxygenation

Background

Prolonged usage of extracorporeal membrane oxygenation (ECMO) may induce multi-organ failure. This study is aimed to evaluate prognostic factors in the patients with ECMO. Also, the prognosis of ECMO with Kidney Injury Network Scoring system is studied.

Materials and Methods

From May 2005 to July 2011, 172 cases of ECMO were performed. The cases of perioperative use of ECMO were excluded. Renal failure patient and younger than 15 years old one were also excluded. As a result, 26 cases were enrolled in this study. Male patients were 15 (57.7%), and mean age was 56.57±17.03 years old. Demographic data, ECMO parameters, weaning from ECMO, and application of continuous renal replacement therapy are collected and Acute Kidney Injury Network (AKIN) scores were evaluated just before ECMO and day 1, day 2 during application of ECMO.

Results

Venoarterial ECMO was applied in 22 cases (84.6%). The reasons for applications of ECMO were cardiac origin in 21 (80.8%), acute respiratory distress syndrome in 4, and septic shock in 1 case. Successful weaning from ECMO was achieved in 15 cases (57.7%), and survival discharge rate was 9 cases (34.6%). Mean duration of application of ECMO was 111.39±54.06 hours. In univariate analysis, myocarditis was independent risk factors on weaning failure. Using the receiver operating characteristic curve, level of hemoglobin on 24 hours after ECMO, and base excess on 48 hours after ECMO were showed more than 0.7. AKIN score was not matched the prognosis of the patients with ECMO.

Conclusion

In our study, the prognosis of the patients with myocarditis was poor. Hemoglobin level at first 24 hours, and degree of acidosis at 48 hours were useful methods in relating with prognosis of ECMO. AKIN scoring system was not related with the prognosis of the patients. Further study for prognosis and organ injury during application ECMO may be needed.

Pivotal role of glutathione depletion in plasma-induced endothelial oxidative stress during sepsis

OBJECTIVE

Plasma from septic shock patients can induce production of reactive oxygen species (ROS) by human umbilical vein endothelial cells (HUVEC) in vitro. How endothelial cells defend themselves against ROS under increased oxidative stress has not yet been examined. This study investigates the antioxidant defenses of HUVEC exposed to plasma obtained from either septic shock patients or healthy volunteers.

DESIGN

Prospective, observational study.

SETTING

Medical intensive care unit in a university hospital.

PATIENTS

Twenty-five patients with septic shock and 10 healthy volunteers.

INTERVENTIONS

Blood samples were collected within the first 24 hrs of septic shock. In vitro HUVEC production of ROS was studied by spectrofluorimetry using 2',7'-dichlorodihydrofluorescein diacetate fluorescent dye. Reactive nitrogen species were also assessed. Intracellular reduced glutathione (GSH) levels were measured using monochlorobimane fluorescent dye. Activity of catalase and superoxide dismutase in HUVEC were also measured. Cell death was assessed using YOPRO fluorescent dye and the MTT assay.

MEASUREMENTS AND RESULTS

On admission, the septic shock population's mean age was 55 yrs old, the mean Sequential Organ Failure Assessment score was 12, mean simplified acute physiology score was 50, and intensive care unit mortality rate was 45%. Evaluation of HUVEC antioxidant defenses showed a significantly decreased GSH level, increased catalase activity, and unchanged superoxide dismutase activity. ROS levels and cell death were significantly reduced when cells were pretreated with N-acetylcysteine or GSH, but no changes in reactive nitrogen species were observed.

CONCLUSION

This study demonstrates that plasma-induced ROS production by HUVEC is associated with an intracellular decrease in reduced GSH. Both ROS levels and cell death decreased when N-acetylcysteine or GSH were added before exposing the cells to plasma. These data suggest a pivotal role of alterations in GSH in damage caused by sepsis-generated ROS in endothelial cell.

Vascular oxidant stress and inflammation in hyperhomocysteinemia

Elevated plasma levels of homocysteine are a metabolic risk factor for atherosclerotic vascular disease, as shown in numerous clinical studies that linked elevated homocysteine levels to de novo and recurrent cardiovascular events. High levels of homocysteine promote oxidant stress in vascular cells and tissue because of the formation of reactive oxygen species (ROS), which have been strongly implicated in the development of atherosclerosis. In particular, ROS have been shown to cause endothelial injury, dysfunction, and activation. Elevated homocysteine stimulates proinflammatory pathways in vascular cells, resulting in leukocyte recruitment to the vessel wall, mediated by the expression of adhesion molecules on endothelial cells and circulating monocytes and neutrophils, in the infiltration of leukocytes into the arterial wall mediated by increased secretion of chemokines, and in the differentiation of monocytes into cholesterol-scavenging macrophages. Furthermore, it stimulates the proliferation of vascular smooth muscle cells followed by the production of extracellular matrix. Many of these events involve redox-sensitive signaling events, which are promoted by elevated homocysteine, and result in the formation of atherosclerotic lesions. In this article, we review current knowledge about the role of homocysteine on oxidant stress-mediated vascular inflammation during the development of atherosclerosis.

Mechanisms involved in the reduced leukocyte migration in intrauterine undernourishment

OBJECTIVE

We investigated factors that may be involved in the reduced leukocyte migration observed in intrauterine undernourished rats.

METHODS

Male Wistar rat offspring (8-9 wk of age) of dams fed during pregnancy with 50% less food than control dams were used to measure L-selectin expression (by flow cytometry), bone marrow cell count, blood cell count, laminin and type IV collagen in the basal membrane of venules of the spermatic fascia (by immunohistochemistry), total protein level and serum albumin, and the production of leukotriene B4 after stimulation with tumor necrosis factor-alpha and corticosterone plasma levels (by enzyme-linked immunosorbent assay).

RESULTS

Hypocellularity in bone marrow and peripheral blood and reduced L-selectin expression were found in the undernourished rat offspring (UR) compared with nourished offspring (NR; P < 0.05). Type IV collagen in the basal membrane of the venules of the spermatic fascia was less in UR than in NR (P < 0.05). The total protein levels and serum albumin did not differ between the two groups. Leukotriene B4 production after stimulation with tumor necrosis factor-alpha was lower in UR (P < 0.05). These differences could not be attributed to circulating glucocorticoids levels, which were not different in the NR and UR groups.

CONCLUSION

Our data suggest that all observed differences contribute to reduced leukocyte migration in undernourishment.

Proteomics of human umbilical vein endothelial cells applied to etoposide-induced apoptosis

We have undertaken to continue the proteomic study of human umbilical vein endothelial cells (HUVECs) using the combination of 2-DE, automated trypsin digestion, and PMF analysis after MALDI-TOF MS and peptide sequencing using nano LC-ESI-MS/MS. The overall functional characterization of the 162 identified proteins from primary cultures of HUVECs confirms the metabolic capabilities of endothelium and illustrates various cellular functions more related to cell motility and angiogenesis, protein folding, anti-oxidant defenses, signal transduction, proteasome pathway and resistance to apoptosis. In comparison with controls cells, the differential proteomic analysis of HUVECs treated by the pro-apoptotic topoisomerase inhibitor etoposide further revealed the variation of eight proteins, namely, GRP78, GRP94, valosin-containing protein, proteinase inhibitor 9, cofilin, 37-kDa laminin receptor protein, bovine apolipoprotein, and tropomyosin. These data suggest that etoposide-induced apoptosis of human vascular endothelial cells results from the intricate involvement of multiple apoptosis processes including at least the mitochondrial and the ER stress pathways. The presented 2-D pattern and protein database, as well as the data related to apoptosis of HUVECs, are available at http://www.huvec.com.

NADPH oxidase and endothelial cell function

Intracellular ROS (reactive oxygen species) such as superoxide and H2O2 have been increasingly appreciated to have a role in endothelial pathophysiology. Of the several sources within the vasculature, a family of multi-subunit NADPH oxidases appears to be a predominant contributor of endothelial superoxide. More importantly, this enzyme system is activated by numerous stimuli and is involved in triggering diverse intracellular signalling pathways (‘redox-sensitive’ signalling pathways) that have a central role in conditions such as endothelial activation and inflammation, cell growth, apoptosis and hypertrophy. Furthermore, NADPH oxidase-derived superoxide contributes to the impairment of endothelium-dependent vasodilatation by inactivating nitric oxide; the resultant endothelial dysfunction is implicated in the pathophysiology of diseases such as atherosclerosis, hypertension, diabetic vasculopathy and heart failure. A detailed understanding of the regulation of NADPH oxidases and their modulation and downstream effects may define novel therapeutic targets for cardiovascular disease prevention and treatment in the clinical setting, in contrast with global antioxidant therapy which has to date been disappointing.

Dynamics of vesicles in a wall-bounded shear flow

We report a detailed study of the behavior (shapes, experienced forces, velocities) of giant lipid vesicles subjected to a shear flow close to a wall. Vesicle buoyancy, size, and reduced volume were separately varied. We show that vesicles are deformed by the flow and exhibit a tank-treading motion with steady orientation. Their shapes are characterized by two nondimensional parameters: the reduced volume and the ratio of the shear stress with the hydrostatic pressure. We confirm the existence of a force, able to lift away nonspherical buoyant vesicles from the substrate. We give the functional variation and the value of this lift force (up to 150 pN in our experimental conditions) as a function of the relevant physical parameters: vesicle-substrate distance, wall shear rate, viscosity of the solution, vesicle size, and reduced volume. Circulating deformable cells disclosing a nonspherical shape also experience this force of viscous origin, which contributes to take them away from the endothelium and should be taken into account in studies on cell adhesion in flow chambers, where cells membrane and the adhesive substrate are in relative motion. Finally, the kinematics of vesicles along the flow direction can be described in a first approximation with a model of rigid spheres.

Adenosine receptors and the control of endothelial cell function in inflammatory disease

The nucleoside adenosine accumulates in many tissues following the onset of ischaemia and inflammation. This initiates a series of protective mechanisms in target cells upon binding and activation of a family of four G-protein-coupled cell surface adenosine receptor (AR) proteins. The magnitude and duration of adenosine's effects are dictated by the identity and expression levels of each receptor subtype on individual cell types within the hypoxic microenvironment. Given the key role of endothelial cells (ECs) in the development of inflammatory diseases, such as sepsis, rheumatoid arthritis (RA) and atherosclerosis, ARs represent attractive targets for therapeutic intervention in these conditions. In this review, we examine several critical aspects of endothelial function in vivo, assess the role of individual AR subtypes in these events and, where known, discuss the molecular mechanisms by which specific ARs exert their effects.

Endothelial cell superoxide generation: regulation and relevance for cardiovascular pathophysiology

The endothelial generation of reactive oxygen species (ROS) is important both physiologically and in the pathogenesis of many cardiovascular disorders. ROS generated by endothelial cells include superoxide (O2-*), hydrogen peroxide (H2O2), peroxynitrite (ONOO-*), nitric oxide (NO), and hydroxyl (*OH) radicals. The O2-* radical, the focus of the current review, may have several effects either directly or through the generation of other radicals, e.g., H2O2 and ONOO-*. These effects include 1) rapid inactivation of the potent signaling molecule and endothelium-derived relaxing factor NO, leading to endothelial dysfunction; 2) the mediation of signal transduction leading to altered gene transcription and protein and enzyme activities ("redox signaling"); and 3) oxidative damage. Multiple enzymes can generate O2-*, notably xanthine oxidase, uncoupled NO synthase, and mitochondria. Recent studies indicate that a major source of endothelial O2-* involved in redox signaling is a multicomponent phagocyte-type NADPH oxidase that is subject to specific regulation by stimuli such as oscillatory shear stress, hypoxia, angiotensin II, growth factors, cytokines, and hyperlipidemia. Depending on the level of oxidants generated and the relative balance between pro- and antioxidant pathways, ROS may be involved in cell growth, hypertrophy, apoptosis, endothelial activation, and adhesivity, for example, in diabetes, hypertension, atherosclerosis, heart failure, and ischemia-reperfusion. This article reviews our current knowledge regarding the sources of endothelial ROS generation, their regulation, their involvement in redox signaling, and the relevance of enhanced ROS generation and redox signaling to the pathophysiology of cardiovascular disorders where endothelial activation and dysfunction are implicated.

Antioxidants in dermocosmetology: from the laboratory to clinical application

Oxygen situated in cutaneous cells can be activated by light. This makes the integumentary apparatus particularly vulnerable to oxidative damage and is responsible for the immediate cutaneous damage that is the basis of late phenomena, such as photo-induced ageing and tumours. Thus, the cosmetic industry has undertaken research and development into antioxidant-based products able to protect the skin from the effect of pro-oxidizing noxae. This review re-examines both antioxidants suitable for dermatological application and skin care products with antioxidant capacity, as well as the laboratory methods used to evaluate the effects and in vivo efficacy of antioxidants.

Transendothelial migration of leukocytes and signalling mechanisms in response to the neuropeptide secretoneurin

Secretoneurin (SN), a newly discovered neuropeptide, may be implicated in inflammatory responses as it was shown to modulate leukocyte, endothelial and mesenchymal cell functions. Neutrophils placed above pulmonary arterial or venous endothelial monolayers migrated through this cellular barrier in response to apical or basal stimulation with SN in a dose-dependent manner. At optimal concentrations of 10(-6) to 10(-8) M, SN was nearly equally effective in stimulating neutrophil transmigration as was tumor necrosis factor-alpha at 10 ng/ml or a chemotactic gradient of formyl-Met-Leu-Phe (10(-8) M). Stimulation of transendothelial migration appears to be specific, since a trypsin digest of SN was ineffective and excess concentrations of anti-SN antibodies completely abolished the effect. Inhibition of cyclooxygenase or nitric oxide synthase did not affect the action of SN. Preincubation of endothelial cells with pertussistoxin (PTx) or choleratoxin (CTx), and the presence of staurosporine significantly inhibited transmigration, suggesting that SN uses a signalling pathway that is coupled to G-proteins and protein kinase C in endothelium. Moreover, SN treatment resulted in transient elevation of cytoplasmatic calcium concentration in endothelial cells. These data support the hypothesis that SN might contribute to neurogenic inflammation in vivo and reveal signalling mechanisms of SN in endothelial cells.

Human neutrophils facilitate tumor cell transendothelial migration

Tumor cell extravasation plays a key role in tumor metastasis. However, the precise mechanisms by which tumor cells migrate through normal vascular endothelium remain unclear. In this study, using an in vitro transendothelial migration model, we show that human polymorphonuclear neutrophils (PMN) assist the human breast tumor cell line MDA-MB-231 to cross the endothelial barrier. We found that tumor-conditioned medium (TCM) downregulated PMN cytocidal function, delayed PMN apoptosis, and concomitantly upregulated PMN adhesion molecule expression. These PMN treated with TCM attached to tumor cells and facilitated tumor cell migration through different endothelial monolayers. In contrast, MDA-MB-231 cells alone did not transmigrate. FACScan analysis revealed that these tumor cells expressed high levels of intercellular adhesion molecule-1 (ICAM-1) but did not express CD11a, CD11b, or CD18. Blockage of CD11b and CD18 on PMN and of ICAM-1 on MDA-MB-231 cells significantly attenuated TCM-treated, PMN-mediated tumor cell migration. These tumor cells still possessed the ability to proliferate after PMN-assisted transmigration. These results indicate that TCM-treated PMN may serve as a carrier to assist tumor cell transendothelial migration and suggest that tumor cells can exploit PMN and alter their function to facilitate their extravasation.

Thermotolerance protects against endotoxin-mediated microvascular injury

An early event in endotoxin-induced tissue injury is adhesion and migration of leukocytes through the endothelium. This is a three-stage process, initially low-grade selectin-mediated adhesion, seen as a decrease in rolling velocity, followed by integrin-mediated adhesion and transmigration. Thermotolerance has been shown to reduce tissue injury and mortality induced by endotoxin. The aim of this study was to investigate the effect of thermotolerance on leukocyte-endothelial interactions. Intravital video microscopy was used to examine hemodynamic parameters, leukocyte rolling, adhesion, and migration in rat mesenteric postcapillary venules. Sprague-Dawley rats were randomized into control, lipopolysaccharide (LPS), and thermotolerance + LPS groups. Thermotolerance was induced 18 h prior to administration of LPS by elevating core body temperature to 41 + 0.5 degrees C for 15 min. LPS (055:B5 15 mg/kg) was administered via the jugular vein after baseline recording. Leukocyte rolling velocity and the number of adherent and migrated leukocytes were measured by intravital microscopy at baseline 0 min and 10, 30, 60, and 90 min after LPS administration. Heat shock protein 72 (HSP72) expression in tissues was determined by Western immunoblotting. The results indicated that LPS administration significantly decreased leukocyte rolling velocity during endotoxemia and increased leukocyte adhesion (10.3 +/- 1.67, 13.2 +/- 1.40, and 10.0 +/- 1.57/100 microm) and migration (5.7 +/- 1.02 and 8.3 +/- 1.76/field) at 30, 60, and 90 min after LPS injection (P < 0.01 vs baseline and control group). Thermotolerance maintained leukocyte rolling velocity and significantly reduced leukocyte adhesion (5.7 +/- 0.88 and 4.0 +/- 0.68/100 microm) and migration (2.8 +/- 0.32 and 3.0 +/- 0.68/field) at 30 and 60 min after LPS administration (P < 0.01 and 0.05 vs LPS group). Expression of HSP72 was induced in mesentery, gut, and lung by thermotolerance. This study indicates that thermotolerance attenuated LPS-induced microvascular injury by decreasing leukocyte-endothelial adhesion and migration.

Effect of leukocyte-endothelial adhesion antagonism on neutrophil migration and neurologic outcome after cortical trauma

BACKGROUND

Administration of anti-CD11B, a monoclonal antibody directed against the leukocyte adhesion molecule CD11B, results in decreased neutrophil infiltration into injured tissue after experimental ischemia. We determined the effect of anti-CD11B administration on neutrophil migration and neurologic functioning after experimental cortical trauma.

METHODS

Injuries were produced by a pneumatic impactor. Treatment animals received anti-CD11B after injury. Neurologic functioning was quantitated at 1, 12, and 24 hours after injury. Neutrophil migration was assessed with the myeloperoxidase assay.

RESULTS

Neutrophil influx was increased in injured cortex after trauma. Anti-CD11B significantly reduced neutrophil influx. There was no significant improvement in neurologic functioning after MAb administration.

CONCLUSIONS

These results show there is marked neutrophil response to injury as produced with the pneumatic contusion model. This migration may be significantly attenuated by administration of a anti-CD11B.

Endothelial activation and response in patients with hand arm vibration syndrome

BACKGROUND

Hand-arm vibration syndrome (HAVS) is a form of secondary Raynaud's phenomenon (RP) of occupational origin. In other forms of RP, blood and blood vessel wall interaction is one factor in the pathophysiology. Cytokines and cell adhesion molecules both play an important role in this interaction, and basal vascular tone and vasodilatation are regulated by nitric oxide.

METHODS

Blood flow responses to acetylcholine (ACh) and sodium nitroprusside (SNP) and levels of soluble intercellular adhesion molecule-1 (sICAM-1) and the inflammatory cytokine interleukin 8 (IL-8) were measured in eight male patients with vibration white finger disease, which is part of HAVS, and in eight healthy matched male control subjects.

RESULTS

sICAM-1 levels were statistically higher (P = 0.02, Mann-Whitney U-test) and IL-8 levels (P < 0.01, Mann-Whitney) were significantly lower in the patient group. The patients with HAVS had significantly reduced vascular responses to SNP (P < 0.05, ANOVA).

CONCLUSIONS

In this study, we reveal differences in vascular responses to SNP that suggest there may be an impairment of the smooth muscle response to nitric oxide in patients with HAVS. The increase in sICAM-1 that occurs in patients with HAVS suggests that leucocyte adhesion is increased and that adherent neutrophils may contribute to the microvascular damage seen in this disease. The impeded flow of blood cells through the microcirculation may result in the low levels of circulating IL-8 due to the cytokine binding to erythrocytes. The possible role of NO activity in HAVS warrants further investigation.

Inhibition of leukocyte adherence and transendothelial migration in cultured human liver vascular endothelial cells by prostaglandin E1

Primary graft dysfunction is a major complication of orthotopic liver transplantation, and hepatic ischemic reperfusion injury is considered to be its major determinant cause. Although oxygen free radicals play an important role, leukocytes, cytokines, and adhesion molecules also contribute to hepatic ischemic reperfusion injury. Prostaglandin E1 (PGE1) has been shown to protect against impairment and dysfunction of transplanted livers in various experimental models as well as in clinical liver transplantation. In this study, the role of PGE1 on leukocyte adherence and transendothelial migration was investigated in cultured human liver vascular endothelial cells (HLVEC). Our results indicated that stimulated, but not resting, leukocytes exhibited high adhesion and transmigration capacity. HLVEC incubated with tumor necrosis factor (TNF) promoted leukocyte adherence and transendothelial migration. PGE1 inhibited leukocyte adherence to HLVEC when it was preincubated with either HLVEC or leukocytes. Moreover, PGE1 also suppressed stimulated leukocyte transendothelial migration in a dose-dependent manner. The inhibitory activity of PGE1 was further investigated on both HLVEC and leukocytes with attention to adhesion molecules. On HLVEC, PGE1 down-regulated TNF-induced expression of endothelial cell leukocyte adhesion molecule 1 and vascular adhesion molecule 1, but not intercellular adhesion molecule 1. On leukocytes, PGE1 inhibited expression of CD11a/CD18 and membrane-bound TNF on PHA-stimulated leukocytes. PGE1 also suppressed TNF release from the stimulated leukocytes. These results indicated that inhibition of leukocyte adherence and transendothelial migration is one of the mechanisms by which PGE1 protects liver grafts.

Effects of rolipram on cyclic AMP levels in alveolar macrophages and lipopolysaccharide-induced inflammation in mouse lung

1. Our previous work demonstrated that bacterial lipopolysaccharide (LPS), administered by aerosol, induced tumour necrosis factor (TNF-alpha) synthesis leading to the infiltration of neutrophils into mice lungs. The treatment of animals with prostaglandin E2 or dibutyryl cyclic AMP impaired both processes. In this study, the target cell for LPS and the modulation by cyclic AMP of TNF-alpha production and neutrophil recruitment were investigated. 2. One hour after inhalation of 2 ml of 0.3 mg ml(-1) LPS, TNF-alpha levels measured by an ELISA method increased in the bronchoalveolar lavage fluid (BALF) of BALB/c mice, reaching a maximal level 3 h after inhalation. The immunocytochemistry assay demonstrated that 1 h after inhalation, 21.2% of alveolar macrophages collected in the BALF were immunopositive for TNF-alpha. 3. When mice were pretreated, i.p., with 20 mg kg(-1) rolipram, a selective inhibitor of phosphodiesterase type 4, TNF-alpha levels in the BALF were significantly reduced and only 7.3% of alveolar macrophages were immunopositive for TNF-alpha. 4. Alveolar macrophages from rolipram-treated mice collected 30 min after inhalation of LPS had a significant increase in the intracellular concentrations of cyclic AMP. This was accompanied by a marked reduction of TNF-alpha levels in the BALF that were associated with a suppression of TNF-alpha mRNA expression. 5. Systemic treatment with 20 mg kg(-1) rolipram almost completely inhibited the LPS-induced neutrophil recruitment, whereas it did not significantly reduce the recruitment induced by rmTNF-alpha. 6. Our results indicate that alveolar macrophages may be the target cells for both the induction and control of the lung inflammatory response to LPS. They also suggest that systemic treatment with cyclic AMP-elevating agents may be useful to control local inflammation resulting from inhalation of bacterial endotoxin.

Aprotinin prevents the development of the trauma-induced multiple organ failure in a chronic sheep model

Trauma-induced multiple organ failure in sheep was prevented by aprotinin therapy. Multiple organ failure was induced in 16 female merino sheep by initial haemorrhagic shock and intramedullary femoral nailing (day 0), and 12 hourly injections of 0.75 micrograms/kg Escherichia coli endotoxin +0.7 ml/kg zymosan-activated plasma (days 1-5). In addition, the aprotinin group (n = 6) received simultaneous injections of 5 mg/kg (35 695 KIU/kg) aprotinin, whereas ten animals did not receive aprotinin and served as the control group (n = 10). Organ functions were monitored for a total of 11 days by measuring haemodynamic, cardio-respiratory and biochemical quantities of blood, urine and epithelial lining fluid. During the subsequent eleven day period, aprotinin induced a significant (p < 0.05) reduction of the pathological changes (development of multiple organ failure) seen in the control group. Thus, aprotinin prevented an alteration of cardiac function (cardiac index for control/aprotinin groups at day 1: 6.5/6.2, and at day 10: 10.47/7.0 1/min x m2), an impairment of lung function (mean pulmonary arterial pressure at day 1: 2.26/1.86, and at day 10: 3.83/2.13 kPa; epithelial lining fluid/plasma ratio of albumin concentrations as a direct marker of lung capillary permeability damage at day 0: 0.18/0.16, and at day 10: 0.45/0.15), a deterioration of liver function (plasma sorbitol dehydrogenase at day 0: 7.9/7.6, and at day 10: 29.6/7.4 U/1), but not of renal function (creatinine clearance at day 1: 91.4/66.1, and at day 10: 53.1/59.2 ml/min). Urinary aprotinin excretion increased up to day 3, then decreased rapidly despite further aprotinin administration. As a non-specific marker of cell damage, plasma lactate dehydrogenase indicated an aprotinin-induced organ protection (day 0: 501/409, and at day 10: 719/329 U/1). The neutrophil count and the measured chemiluminescence of neutrophils from the blood and epithelial lining fluid showed that aprotinin reduced the in vivo neutrophil activation, the alveolar neutrophil invasion, the production of inflammatory mediators, and the production of reactive oxygen metabolites during the passage of the capillary-interstitial-alveolar space by neutrophils.

L-arginine reduces endothelial inflammation and myocardial stunning during ischemia/reperfusion

BACKGROUND

This study evaluated whether the nitric oxide precursor L-arginine could reduce ischemia/reperfusion injury by preventing leukocyte-endothelial interactions.

METHODS

Normothermic regional ischemia was induced in the open-chest working pig heart for 30 minutes followed by 90 minutes of reperfusion. A preischemic 10-minute intravenous infusion of 4 mg.kg-1.min-1 of L-arginine (n = 12) was compared with 12 control pigs. Nitric oxide release was measured from the coronary sinus using an amperometric probe. Left ventricular function, malonaldehyde, creatine kinase, myocardial oxygen extraction, and the soluble adhesion molecules (intracellular adhesion molecule-1, endothelial leukocyte adhesion molecule-1, and vascular cell adhesion molecule-1) were measured.

RESULTS

Nitric oxide release was significantly reduced from baseline throughout ischemia/reperfusion only in the control group. Systolic and diastolic function, and myocardial oxygen extraction were also significantly decreased during early reperfusion in the control compared with the L-arginine group. Peak creatine kinase release was not significantly different between groups. The incidence of ventricular fibrillation, malonaldehyde release, and soluble intracellular adhesion molecule-1, endothelial leukocyte adhesion molecule-1, and vascular cell adhesion molecule-1 were each significantly decreased during reperfusion in the L-arginine group.

CONCLUSIONS

L-Arginine reduced lipid peroxidation, plasma levels of soluble adhesion molecules, myocardial stunning, and arrhythmias. These results support an excessive endothelial injury/inflammatory response after regional ischemia/reperfusion that can be ameliorated through augmented nitric oxide.

Cytoadhesion and Falciparum Malaria: Going with the flow

Sequestration of parasitized red blood cells in the cerebral vasculature is the predisposing event to the development of cerebral malaria during infection with Plasmodium falciparum. The adhesive interaction between these cells and receptors on the endothelial cell (cytoadhesion) occurs in the dynamic environment of the microcirculation, but most studies have neglected this factor and have concentrated on measuring adhesion in static (no flow) assays. Such studies ignore the markedly different rheological properties of parasitized red blood cells that become apparent when adhesion is examined under dynamic, flow conditions that resemble those of the circulation in vivo. Here, Brian Cooke and Ross Coppel review a number of novel aspects of cytoadhesion that have been identified using flow-based assays, and discuss their relevance to the pathophysiology, investigation and clinical management of falciparum malaria.