Biomedical subjects

F N Miller

Publications and source records attributed to F N Miller.

At least 19 recordsLinked to original sources

PubMed2001

Leukocyte-endothelial adhesion is impaired in the cremaster muscle microcirculation of the copper-deficient rat.

Dietary copper deficiency impairs the function of both the vascular endothelium and circulating leukocytes. In the current study, leukocyte-endothelium adhesion was observed in the in vivo cremaster muscle microcirculation of copper-adequate and copper-deficient rats. Male, weanling Sprague-Dawley rats were fed purified diets that were either adequate (5.6 microg/g) or deficient (0.3 microg/g) in copper. Adhesion was stimulated with the inflammatory mediators tumor necrosis factor-alpha and bradykinin, and the chemotactic peptide N-formyl-methionyl-leucyl-phenylalanine. Intravascular adhesion of leukocytes to the vascular endothelium was significantly attenuated in the copper-deficient group in response to all three agonists. These results occurred without any difference in intravascular wall shear rate between the dietary groups. Based on previous work, we propose that the attenuated response is caused by either decreased expression of adhesion molecules on leukocytes and endothelial cells or by inhibition of the endothelial cell calcium signaling associated with copper deficiency.

Animals↗

PubMed2001

The initiating factors of late preconditioning in skeletal muscle.

PURPOSE: The goal of these studies was to determine the initiating factors for late preconditioning in the microcirculation of skeletal muscle. MATERIALS AND METHODS: The cremaster muscle of male Sprague-Dawley rats underwent 4 h of ischemia and then 60 min of reperfusion. Ischemic preconditioning (IPC) consisted of 45 min of ischemia but was done 24 h before the 4 h of ischemia. To mimic the effects of IPC in the late phase, adenosine (ADO) or sodium nitroprusside (SNP) was given 24 h before the prolonged ischemia via local intraarterial infusion. To block the effects of IPC in the late phase, 8-sulfophenyl-theophylline (a nonspecific ADO receptor blocker) or N(W)-nitro-l-arginine (a nonselective nitric oxide synthase antagonist) was given prior to IPC. Microvascular response to IPC and pharmacological preconditioning were determined by measuring arteriole diameters and capillary perfusion using intravital microscopy. RESULTS: Administration of ADO or SNP on day 1 without IPC produced a similar microvascular protection against prolonged ischemia/reperfusion on day 2 as that induced by IPC alone. In contrast, blocking ADO receptors or nitric oxide synthase on day 1 just prior to IPC eliminated the IPC-induced microvascular protection seen on day 2. In addition, inhibition of nitric oxide synthase on day 1 diminished the protection induced by ADO, but blocking ADO receptors on day 1 did not compromise the protection induced by SNP. CONCLUSION: The results from these studies suggest that up regulation of ADO is the initiating factor with secondary up regulation of nitric oxide in late preconditioning. Both ADO and nitric oxide contribute to initiating microvascular protection in the late phase of IPC.

Adenosine↗

PubMed2000

Docosahexaenoic acid reverses cyclosporin A-induced changes in membrane structure and function.

The use of a fish oil vehicle for cyclosporin A (CsA) can decrease the toxic effects of CsA but the mechanism is unclear. Here we examine the mechanism by which docosahexaenoic acid (DHA), a fish oil-derived polyunsaturated fatty acid, can alter the toxic effects of CsA on mouse organ function, endothelial macromolecular permeability, and membrane bilayer function. Mice given CsA and fish oil showed increased liver toxicity, kidney toxicity, incorporation of DHA, and evidence of oxidized fatty acids compared to control animals. We hypothesized that the toxic effects of CsA were primarily a result of membrane perturbation, which could be decreased if DHA were not oxidized. The presence of CsA (10 mol%) alone increased dipalmitoylphosphatidylcholine membrane permeability by seven fold over control (no CsA, no DHA). However, if non-oxidized DHA (15 mol%) and CsA were added to the membrane, the permeability returned to control levels. Interestingly, if the DHA was oxidized, the antagonistic effect of DHA on CsA was completely lost. While CsA alone increased endothelial permeability to albumin, the combination of non-oxidized DHA and CsA had no effect on endothelial macromolecular permeability. However the combination of oxidized DHA and CsA was no different than the effects of CsA only. CsA increased the fluorescence anisotropy of DPH in the liquid crystalline state of DPPC, while DHA decreased fluorescence anisotropy. However the combination of CsA and DHA was no different than DHA alone. We conclude that non-oxidized DHA can reverse the membrane perturbing effects of CsA, and the increases in endothelial macromolecular permeability, which may explain how fish oil is capable of decreasing the toxicity of CsA.

Animals↗

PubMed2000

Platelet-activating factor contributes to postischemic vasospasm.

BACKGROUND: The purpose of the present study was to determine if platelet-activating factor is an important mediator that produces vasospasm during reperfusion after ischemia in skeletal muscle. MATERIALS AND METHODS: A vascular isolated cremaster muscle in male Sprague-Dawley rats was coupled with local intraarterial drug infusion as a model to study microcirculation responses to ischemia/reperfusion injury. Arteriole diameters and capillary perfusion were measured using intravital microscopy. Group 1: platelet-activating factor dose response. Group 2: Effects of a cyclooxygenase inhibitor; indomethacin, and a thromboxane synthetase inhibitor, imidazole, on the response to platelet-activating factor. Group 3: Effects of nitric oxide synthesis inhibitor; N(omega)-nitro-L-arginine methyl ester, on the response to platelet-activating factor. Group 4: Effects of a platelet-activating factor receptor antagonist, CV-3988, indomethacin, and imidazole after 4 h of warm ischemia and reperfusion. RESULTS: Intraarterial infusion of platelet-activating factor produced a dose-related but mild vasoconstriction. Pretreatment with indomethacin or imidazole resulted in significant vasodilation actually emanating from platelet-activating factor infusion. Nitric oxide inhibition (with N(omega)-nitro-L-arginine methyl ester) enhanced the vasoconstriction produced by platelet-activating factor. Pretreatment with CV-3988, indomethacin, or imidazole significantly attenuated ischemia/reperfusion-induced vasospasm and capillary no-reflow in the cremaster muscles. CONCLUSIONS: Ischemia/reperfusion-induced vasoconstriction is at least in part mediated by platelet-activating factor and thromboxane A(2).

Animals↗

PubMed2000

Bradykinin and alpha-thrombin increase human umbilical vein endothelial macromolecular permeability by different mechanisms.

Bradykinin and alpha-thrombin both increase endothelial macromolecular permeability, however the mechanism for this effect is unclear. Human umbilical vein endothelial cell (HUVEC) permeability to human serum albumin was increased by 1 microM alpha-thrombin (AT) or bradykinin (BK), but the kinetics of the permeability response were different. Intracellular calcium mobilization of HUVEC by AT was increased, yet BK had no effect on intracellular calcium. Distribution of F-actin and content was increased by AT as early as 10 minutes after administration, yet BK had no affect on F-actin when compared to control. We hypothesized that BK may increase HUVEC permeability by producing matrix metalloproteinase-2 (MMP-2). The AT-treated HUVEC produced an intermediate 64 kDa MMP-2, whereas BK-treated HUVEC increased the intermediate 64 kDa MMP-2 and also an active 62 kDa MMP-2. Pre-treatment of the HUVEC with tissue inhibitor of matrix metalloproteinase-2 slightly decreased the AT-induced increase in macromolecular permeability and completely inhibited the BK-induced increase in macromolecular permeability.

Actins↗

PubMed2000

Initiation of microvascular protection by nitric oxide in late preconditioning.

The authors hypothesized that nitric oxide is induced by a brief period of ischemia/reperfusion (ischemic preconditioning, IPC) on postoperative day (POD) 1, and that this released nitric oxide is responsible for initiating a delayed microvascular protection against a prolonged period of ischemia in skeletal muscle on POD day 2. The cremaster muscle of male Sprague-Dawley rats underwent 4 hr of ischemia, and then 60 min of reperfusion. IPC consisted of 45 min of ischemia but was done 24 hr before the prolonged ischemia. Local intraarterial infusion of sodium nitroprusside (SNP, a donor of nitric oxide) or Nw-nitro-L-arginine (L-NA, a nonselective nitric oxide synthase antagonist) were also given 24 hr before prolonged ischemia. Arteriole diameters and capillary perfusion were measured using intravital microscopy. Four groups were compared: 1) control; 2) IPC; 3) SNP + sham IPC; and 4) L-NA + IPC. Four hours of ischemia followed by reperfusion created a significant vasoconstriction and capillary no-reflow in the microcirculation of cremaster muscles. These alterations were largely prevented by IPC. Local intraarterial infusion of SNP without IPC created a similar microvascular protection to that induced by IPC alone. In contrast, intraarterial infusion of L-NA prior to IPC eliminated the IPC-induced microvascular protection. In conclusion, in late preconditioning, nitric oxide contributes to the initiation of a delayed microvascular protection against prolonged ischemia in skeletal muscle.

Animals↗

PubMed2000

Endothelial cell calcium mobilization to acetylcholine is attenuated in copper-deficient rats.

Dietary copper deficiency significantly attenuates nitric oxide (NO)-mediated vascular smooth muscle relaxation and vasodilation. There is evidence for both increased inactivation of the NO radical by superoxide anion, and oxidative damage to the endothelium where NO is produced. The current study was designed to examine the NO synthetic pathway in the endothelium during copper deficiency. Male weanling rats were fed a copper-adequate (CuA, 6.4 mg Cu/kg diet) or copper-deficient (CuD, 0.4 mg Cu/kg diet) diet for four weeks. Cremasteric arterioles (approximately 100 microm diameter) were isolated and used for the experiments. Western blot analysis of the arteriole endothelial nitric oxide synthase (eNOS) concentration did not show a difference between dietary groups. Acetylcholine (Ach)-induced vasodilation was significantly reduced in the CuD group both before and after pretreatment with the eNOS substrate L-arginine. Endothelial intracellular calcium ([Ca2+]i) stimulated by 10(-6) M Ach was significantly inhibited in the arterioles from CuD rats. Coincident with the inhibition of [Ca2+]i and vasodilation was a depression of vascular Cu/Zn-SOD activity and an increase in plasma peroxynitrite activity. These data suggest that endothelial Ca2+ signaling and agonist-stimulated NO-mediated vascular dilation are likely reduced by increased oxidative damage in copper-deficient rats.

Acetylcholine↗

PubMed1999

Endocytosis of heparin-binding protein (CAP37) is essential for the enhancement of lipopolysaccharide-induced TNF-alpha production in human monocytes.

Heparin-binding protein (HBP), also known as CAP37, is a proteolytically inactive serine protease homologue that is released from activated granulocytes. However, HBP is not a biologically inactive molecule but rather a multifunctional protein with properties that include the enhancement of LPS-induced TNF-alpha production from monocytes. We have previously demonstrated that HBP is internalized in monocytes. In the current study, we hypothesize that HBP is internalized in monocytes via endocytosis, and this internalization is an important mechanism by which HBP enhances LPS-induced TNF-alpha release. Using whole blood from healthy donors and flow cytometry, we found that colchicine (0.1-10 mM), cytochalasin D (1000 microM), NH4Cl (10-50 mM), and bafilomycin A1 (0.1-3 microM) significantly reduced the affinity of FITC-HBP for CD14-positive monocytes. Using isolated human monocytes and ELISA, we found that colchicine (0.1 mM), cytochalasin D (30 and 300 microM), NH4Cl (30 mM), and bafilomycin A1 (1 microM) significantly reduced the effect of HBP (10 microg/ml) to enhance LPS (10 ng/ml)-induced TNF-alpha release after 24 h. These findings demonstrate that internalization of HBP in monocytes is essential for the enhancement of LPS-induced TNF-alpha release. Transport of HBP to an activating compartment depends on intact F-actin polymerization and endosomal acidification, an important mechanism for endosomal protein sorting and trafficking.

Adjuvants, Immunologic↗

PubMed1999

Relationship between dietary copper concentration and acetylcholine-induced vasodilation in the microcirculation of rats.

Dietary copper deficiency has been shown to significantly reduce acetylcholine (Ach)-induced vascular smooth muscle relaxation. The current study was designed to examine the relative relationship between dietary copper and the vasodilator response to Ach in the microcirculation of the rat. Male weanling rats were fed a purified basal diet supplemented with 6.0, 3.0, 1.5 or 0.0 microg Cu/g diet for 4 weeks to provide an adequate, two marginal, and deficient intakes of dietary copper. Arteriole dilation in response to increasing concentrations of acetylcholine (10(-7) to 10(-4) M) was measured in the in vivo cremaster muscle microcirculation for each dietary group. Liver copper and both aortic and erythrocyte Cu,Zn-SOD activity were used as indices of systemic copper status. Dilation to the increasing concentrations of Ach was only different in the 0 microg Cu supplemented group compared to the copper-adequate control values. However, the combined results showed an exponential increase in 10(-5) M Ach-induced vasodilation as liver copper concentration increases from 0 microg Cu/g dry wt. This relationship suggests that dilation is attenuated at liver Cu concentrations below 5 microg/g dry wt. The results indicate that Ach-induced vasodilation is copper-dependent but that the pathway is not very sensitive to short-term marginal restriction of copper intake.

Acetylcholine↗

PubMed1999

Enhanced pulmonary expression of CXC chemokines during hepatic ischemia/reperfusion-induced lung injury in mice.

BACKGROUND: Hepatic ischemia/reperfusion injury during both hepatic resection and transplantation may lead to local and systemic organ dysfunction. Proinflammatory mediators released by Kupffer cells during the initial phase of ischemia/reperfusion are thought to be involved in the development of neutrophil-mediated lung injury. However, the precise factors involved in lung recruitment of neutrophils are unclear. The objective of current study was to determine whether the CXC chemokines, macrophage inflammatory protein-2 (MIP-2) and KC, contribute to pulmonary neutrophil recruitment and injury following hepatic ischemia/reperfusion. METHODS: C57BL/6 mice were subjected to 90 min of partial hepatic ischemia and 3, 6, and 9 h of reperfusion. Neutrophil accumulation in lung was assessed by lung content of myeloperoxidase (MPO). MIP-2 and KC mRNA were measured using RT-PCR. Lung edema was quantified by wet to dry weight ratios. RESULTS: Three hours after hepatic reperfusion, serum levels of tumor necrosis factor-alpha were increased. Lung expression of both MIP-2 and KC mRNA was also increased at this time. Both MIP-2 and KC mRNA expression remained elevated 9 h after reperfusion, although levels of MIP-2 mRNA were significantly lower than at 3 h. Pulmonary recruitment of neutrophils was increased within 3 h after reperfusion, but returned to baseline levels by 9 h. Lung edema was increased 3 and 9 h after reperfusion. Neutralization of MIP-2 or KC with antibody significantly decreased lung edema 9 h after reperfusion. CONCLUSIONS: These data suggest that mediators released during hepatic ischemia/reperfusion induce the expression of MIP-2 and KC in the lung. In addition, it appears that MIP-2 and KC contribute to lung neutrophil accumulation and the associated pulmonary injury following hepatic ischemia/reperfusion.

Animals↗

PubMed1999

A new continuous monitoring system for simultaneous measurements of intracellular calcium and either endothelial permeability or leukocyte extravasation.

OBJECTIVE AND DESIGN: We have developed a continuous monitoring system that will quantify lymphocyte extravasation or intercellular permeability with intracellular calcium measurements in a single preparation. MATERIALS: Human microvascular endothelial cells, human lymphocytes and histamine. TREATMENT: Endothelial barrier function and intracellular calcium were examined upon application of either human lymphocytes (1 x 10(5) cells/ml) or histamine (1 microM). METHODS: Endothelial cells labeled with FURA-2 were examined for both changes in endothelial barrier function and mobilization of intracellular calcium using fluorescence spectroscopy and ratio imaging, respectively. RESULTS: Increases in endothelial intracellular calcium occur in the first minute and are followed by increases in endothelial intercellular permeability to albumin (5-7 min) or lymphocytes (15-20 min). Approximately 60 min following calcium mobilization, there was a second and larger extravasation. CONCLUSION: The continuous monitoring system expands our understanding of the time course of the permeability and extravasation events to mobilization of endothelial intracellular calcium.

Adult↗

PubMed1999

Mechanisms of leukocyte-mediated tissue injury induced by interleukin-2.

In this review we discuss the effects of interleukin-2 (IL-2) therapy on trafficking of leukocytes and platelets to normal organs. The use of animal models has allowed the elucidation of events leading to damage and/or dysfunction of normal tissues after IL-2 administration. These studies have shown that acute toxicity induced by IL-2 is mediated primarily by neutrophils. Chronic toxicity results from the adhesion and transmigration of activated lymphocytes into normal organs. Platelet-derived microvascular thrombosis also contributes to the vascular toxicity of IL-2. A better understanding of these mechanisms may lead to the development of interventions that will significantly improve the therapeutic efficacy of IL-2.

Animals↗

PubMed1999

Quantitative image analysis of F-actin in endothelial cells.

OBJECTIVE: Filamentous actin (F-actin) plays a central role in maintaining endothelial barrier function. Thrombin and histamine, two inflammatory mediators that increase endothelial permeability, can alter F-actin production and distribution. In this study, we use a newly developed image analysis technique to show that these two inflammatory mediators differentially alter F-actin structure. METHODS: Human umbilical vein endothelial cells were grown to confluence and treated with either histamine (1 microM), thrombin (1 microM) or the agonist's vehicle. The endothelium was stained with BODIPY-phallodin, and digitized images were taken of the treated cells. The digitized images of individual human umbilical vein endothelial cells (HUVEC) were imported into a F-actin image analysis program (FAAP) and converted to layers, each one pixel thick. The program then determined the mean gray level (which corresponded to the amount of F-actin) in each layer starting from the outside of the cell (layer 1) and progressing in one pixel layer increments towards the center of the cell (layer 32). RESULTS: Both inflammatory mediators increased endothelial F-actin production, however, the distribution of the actin was different. Thrombin increased the presence of stress fibers, while also decreasing peripheral banding actin. In contrast, histamine had no effect on peripheral actin compared to control, but did increase the presence of F-actin stress fibers. CONCLUSIONS: These results establish that thrombin and histamine alter endothelial F-actin production in different locations within the cell, which can be quantified using an image analysis program.

Actins↗

PubMed1998

Heparin-binding protein (CAP37) is internalized in monocytes and increases LPS-induced monocyte activation.

Previous studies have shown that the neutrophil-derived heparin-binding protein (HBP), also known as CAP37 or azurocidin, potentiates the LPS-induced release of proinflammatory cytokines (TNF-alpha, IL-1, and IL-6) from isolated human monocytes. To date, the mechanisms by which HBP enhances LPS-induced monocyte activation have not been elucidated, and it is not known whether HBP also increases the LPS-induced production of other bioactive substances. We studied human monocytes activated by recombinant human HBP and LPS and their interaction with the LPS receptor CD14. We hypothesized that the stimulatory effect of HBP on the LPS-induced release of proinflammatory mediators from monocytes was mediated by specific binding of HBP to monocytes, which resulted in an up-regulation of CD14. Our results demonstrated that HBP alone (10 microg/ml) stimulated the production of TNF-alpha from isolated monocytes. In addition, HBP had an additive effect on LPS-induced production of TNF-alpha and PGE2, suggesting a generalized monocyte activation. We used flow cytometry to demonstrate that HBP had a high affinity to monocytes but not to the LPS receptor CD14, and experiments performed at 4 degrees C indicated an energy-dependent step in this process. Confocal microscopy showed that monocytes internalize HBP within 30 min. These data suggest that mechanisms other than increased CD14 expression are responsible for the enhanced release of TNF-alpha or PGE2 in response to HBP and LPS.

Adjuvants, Immunologic↗

PubMed1998

Chemokine involvement in hepatic ischemia/reperfusion injury in mice: roles for macrophage inflammatory protein-2 and Kupffer cells.

Hepatic injury induced by ischemia and reperfusion is an important clinical problem after liver resection or transplantation. Neutrophils are known to mediate the organ injury, but the precise mechanisms leading to hepatic neutrophil recruitment are undefined. Two CXC chemokines, macrophage inflammatory protein-2 (MIP-2) and KC, are potently chemotactic for neutrophils in vitro and have been reported to be involved in neutrophil-dependent inflammatory tissue injury. The objective of the present study was to determine the roles of MIP-2 and KC in the induction of hepatic ischemia/reperfusion injury. C57BL/6 mice were subjected to 90 minutes of partial hepatic ischemia followed by reperfusion. Hepatic injury was associated with neutrophil sequestration, edema, and elevated serum levels of hepatic transaminases. The expression of MIP-2 messenger RNA (mRNA) was induced within 3 hours after reperfusion, before any detectable increase in neutrophil accumulation, and was also increased to a greater extent in the ischemic lobe after 9 hours of reperfusion. These data suggest that MIP-2 may be involved in the initial recruitment of neutrophils to the ischemic lobe. In contrast, KC mRNA expression was not increased after 3 hours of reperfusion but after 9 hours increased equivalently in both ischemic and nonischemic lobes, suggesting a more generalized role in neutrophil recruitment. Neutralization of MIP-2 or KC resulted in significant decreases in hepatic neutrophil accumulation, edema, and hepatocellular injury. These data suggest that the local expression of MIP-2 and KC are important mediators involved in neutrophil-dependent hepatic injury induced by ischemia and reperfusion in mice.

Alanine Transaminase↗

PubMed1998

Chemokine involvement in hepatic ischemia/reperfusion injury in mice: roles for macrophage inflammatory protein-2 and KC.

Hepatic injury induced by ischemia and reperfusion is an important clinical problem after liver resection or transplantation. Neutrophils are known to mediate the organ injury, but the precise mechanisms leading to hepatic neutrophil recruitment are undefined. Two CXC chemokines, macrophage inflammatory protein-2 (MIP-2) and KC, are potently chemotactic for neutrophils in vitro and have been reported to be involved in neutrophil-dependent inflammatory tissue injury. The objective of the present study was to determine the roles of MIP-2 and KC in the induction of hepatic ischemia/reperfusion injury. C57BL/6 mice were subjected to 90 minutes of partial hepatic ischemia followed by reperfusion. Hepatic injury was associated with neutrophil sequestration, edema, and elevated serum levels of hepatic transaminases. The expression of MIP-2 messenger RNA (mRNA) was induced within 3 hours after reperfusion, before any detectable increase in neutrophil accumulation, and was also increased to a greater extent in the ischemic lobe after 9 hours of reperfusion. These data suggest that MIP-2 may be involved in the initial recruitment of neutrophils to the ischemic lobe. In contrast, KC mRNA expression was not increased after 3 hours of reperfusion but after 9 hours increased equivalently in both ischemic and non-ischemic lobes, suggesting a more generalized role in neutrophil recruitment. Neutralization of MIP-2 or KC resulted in significant decreases in hepatic neutrophil accumulation, edema, and hepatocellular injury. These data suggest that the local expression of MIP-2 and KC are important mediators involved in neutrophil-dependent hepatic injury induced by ischemia and reperfusion in mice.

Animals↗

PubMed1998

Heparin binding protein (CAP37) is an opsonin for Staphylococcus aureus and increases phagocytosis in monocytes.

Heparin binding protein (HBP), also known as cationic antibiotic protein (CAP37) or azurocidin, is stored in azurophilic granules of neutrophils and is released to the extracellular space when granulocytes phagocytose Staphylococcus aureus. We investigated whether extracellular HBP also has the potential to increase phagocytosis of S. aureus by other phagocytes. We used flow cytometry to characterize the binding of HBP to S. aureus and to simultaneously measure phagocytosis and superoxide production of opsonized S. aureus in monocytes and granulocytes. Our results demonstrate that HBP is a strong opsonin for S. aureus, and that monocytes, but not granulocytes, increase phagocytosis of HBP-treated S. aureus. However, HBP-treated S. aureus increases the production of superoxide in both monocytes and granulocytes as compared with untreated S. aureus. These findings support the role of granulocytes in the afferent limb of inflammation and demonstrate that HBP, when released from activated granulocytes, potentiates bacterial uptake in monocytes and enhances the potential of microbial killing in monocytes and granulocytes.

Antimicrobial Cationic Peptides↗

PubMed1998

Modulation of lipopolysaccharide-induced monocyte activation by heparin-binding protein and fucoidan.

Activated polymorphonuclear leukocytes release heparin-binding protein (HBP; also known as CAP37 or azurocidin) from azurophilic granules. HBP is a strong chemoattractant for monocytes that also prolongs monocyte survival and potentiates endotoxin (lipopolysaccharide [LPS])-induced production of tumor necrosis factor alpha (TNF-alpha). We investigated the binding of fluorescein isothiocyanate-conjugated HBP to human monocytes in the presence of EDTA and the polysaccharide fucoidan. EDTA, which chelates divalent cations, has been widely used to study the role of divalent cations in receptor-ligand interactions or enzyme activity. Fucoidan has been used to inhibit the binding of various ligands to scavenger receptors or selectins. Scavenger receptors are multiligand receptors that mediate endocytosis of proteases, protease-inhibitor complexes, lipoproteins, and LPS-lipid A. Fucoidan also interferes with leukocyte rolling by binding to L-selectins (expressed on leukocytes) and P-selectins (expressed on platelets and endothelium). We demonstrate that the binding of the neutrophil-derived protein HBP to monocytes is inhibited in the presence of EDTA and fucoidan. In addition, fucoidan and EDTA abrogate the enhancing effect of HBP on LPS-induced TNF-alpha production. These data provide supporting evidence that HBP binds to a receptor expressed on monocytes. This receptor is dependent on divalent cations and is possibly related to the scavenger receptor. Furthermore, we demonstrate that fucoidan, by itself, stimulates TNF-alpha release from isolated monocytes in a CD14-independent fashion. This is an important finding for the interpretation of results from studies that use fucoidan to "block" either scavenger receptors or L- or P-selectins.

Antimicrobial Cationic Peptides↗