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P Kubes

Publications and source records attributed to P Kubes.

At least 55 records · Page 3Linked to original sources
PubMed1999

Assessment of the mechanism of juxtacrine activation and adhesion of leukocytes in liver microcirculation.

Leukotriene C4 (LTC4), histamine, and other mediators can induce expression of P-selectin and platelet-activating factor (PAF) on venular endothelium to recruit leukocytes in vivo and in vitro via a juxtacrine mechanism of adhesion. The objective of this study was to assess the effect of histamine and LTC4 on the leukocyte recruitment in the liver and to study the components and molecular mechanisms involved in this process. We visualized the hepatic microvasculature using intravital microscopy and we determined that LTC4 (20 nM) but not histamine (0.1, 0.3, or 1 mM) induced leukocyte recruitment in the liver microcirculation. Histamine could induce leukocyte recruitment but only in the presence of an antihistaminase. The LTC4-induced leukocyte recruitment occurred primarily in sinusoids (not venules) and was not inhibitable by three different anti-P-selectin antibodies (5H1, RMP-1, and RB40). Leukocyte recruitment in P-selectin-deficient mice, intercellular adhesion molecule 1 (ICAM-1)-deficient mice, and mice treated with a PAF antagonist was of the same magnitude as in wild-type animals in response to LTC4. Although PAF alone could induce adhesion in both sinusoids and postsinusoidal venules, this chemotactic agent was not involved in LTC4-induced adhesion in the liver. Finally, an overlapping role for P-selectin and ICAM-1 was ruled out as LTC4 induced leukocyte recruitment in P-selectin and ICAM-1 double-deficient mice. These data demonstrate that LTC4 does not activate the known early mechanisms of leukocyte recruitment, including P-selectin, PAF, or ICAM-1 in the hepatic microvasculature.

Animals↗
PubMed1999

Inhaled NO impacts vascular but not extravascular compartments in postischemic peripheral organs.

Inhaled nitric oxide (NO) reduces pulmonary hypertension and dampens various aspects of lung inflammation; however, its effects are thought to be restricted to the lung because of its short half-life in biological systems. More recently, however, NO was shown to nitrosylate hemoglobin, albumin, and other plasma molecules to form stable nitrosothiol derivatives and could have an impact on the periphery. We examined whether inhaled NO could have an impact on the two compartments of distal organs, namely, the intravascular and extravascular spaces. The feline intestine was exposed to 1 h of ischemia and 1 h of reperfusion, and intestinal blood flow and mucosal dysfunction were measured in animals ventilated with room air and inhaling 0 or 80 ppm NO. A decrease in intestinal blood flow and an increase in mucosal barrier leakiness were noted in animals not exposed to inhaled NO. The intestinal blood flow impairment was entirely reversed in animals breathing 80 ppm NO, but the mucosal dysfunction was not affected. We further examined whether inhaled NO could reach the extravascular space by simply inhibiting NO in the intestine with the NO synthase inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME) that causes an increase in mucosal permeability that is rapidly reversed with NO donors. However, inhaled NO had no effect on the rise in mucosal permeability. L-NAME reduced lymph nitrosothiol concentrations, but inhaled NO could not replenish these levels. To further explore the intravascular impact of inhaled NO, we used intravital microscopy to visualize the microvasculature and demonstrated that inhaled NO could be initiated after reperfusion and still reduced microvascular disturbances, including reversing the impairment in blood flow and increasing leukocyte adhesion. The effects of inhaled NO persisted for an additional hour after termination of NO inhalation, consistent with a dramatic increase in nitrate within 1 h of NO inhalation, which persisted for 1 h after the termination of NO inhalation. These data suggest that inhaled NO can reach distal organs to dramatically improve reperfusion-induced microvascular but not extravascular dysfunction.

Administration, Inhalation↗
PubMed1999

Endothelin-1 causes P-selectin-dependent leukocyte rolling and adhesion within rat mesenteric microvessels.

Endothelin-1 (ET-1) is a potent vasoconstrictor postulated to play a role in hypertension, ischemia-reperfusion, and atherosclerosis. In addition to these contributions, it has been also proposed to induce leukocyte-endothelial cell interactions. The aim of the present study was to assess the mechanisms of action of ET-1 on leukocyte recruitment in vivo. Intravital microscopy of the rat mesenteric postcapillary venules was used. Ten minutes after 1 nM ET-1 superfusion, a significant increase in leukocyte rolling (77.5 +/- 22.6 vs. 20.5 +/- 4.5 cells/min) and adhesion (15.5 +/- 2.9 vs. 3.0 +/- 0.8 cells/100 micrometer) but not emigration was observed. These effects were found not to be mediated by mast cell activation. No platelet-endothelial cell interactions were detected in this in vivo system and furthermore, flow cytometry analysis revealed no increase of P-selectin expression in rat platelets on ET-1 stimulation. Pretreatment of animals with an anti-rat P-selectin monoclonal antibody (mAb) dramatically reduced leukocyte rolling and adhesion by 100 and 94% respectively when compared with control mAb-treated animals. At this dose of ET-1, a very transient decrease in shear rate was detected, arteriolar diameter was significantly reduced but venular diameter remained unchanged. A similar mechanical reduction in blood flow did not induce leukocyte recruitment. Thus this study demonstrates that ET-1 can directly cause significant leukocyte rolling and adhesion adding to its potential pathophysiological role in the development of disease states of the cardiovascular system.

Animals↗
PubMed1999

Inhaled NO reaches distal vasculatures to inhibit endothelium- but not leukocyte-dependent cell adhesion.

Nitric oxide (NO), in addition to being a potent vasodilator, also prevents leukocyte adhesion in the microvasculature. Based on the antiadhesive properties of NO and work suggesting that NO is transported by proteins in the circulation, we tested the possibility that inhaled NO could impart antiadhesive effects in peripheral microvessels. We also determined the underlying mechanisms of actions. Three well-established models that induce local microvascular changes (either endothelium or leukocyte) were used. Hydrogen peroxide (H(2)O(2); 100 microM) was superfused onto the cat mesentery to induce an endothelium-derived, P-selectin- and platelet-activating factor-dependent, oxidant-dependent leukocyte recruitment. In a second series of experiments, the cat mesentery was superfused with histamine (100 microM) to induce rapid endothelium-derived, P-selectin- and platelet-activating factor-dependent, oxidant-independent leukocyte recruitment. Finally, in a third series of experiments to target the leukocyte (but not the endothelium) directly in the periphery, the chemotactic molecule leukotriene B(4) (20 nM) was superfused onto the cat mesentery. The above experiments were performed with and without cats breathing NO (80 parts/million). Intravital microscopy was used to visualize the mesenteric microcirculation. Inhaled NO reduced the increased leukocyte rolling and adhesion associated with H(2)O(2) superfusion of the feline mesentery via a cGMP-dependent mechanism. In contrast, inhaled NO had no effect on the histamine-induced increase in leukocyte rolling flux but partially inhibited the subsequent adhesion. The leukocyte chemotactic mediator leukotriene B(4) induced a significant increase in leukocyte adhesion, but NO inhalation did not impair this chemotactically induced leukocyte recruitment. These data suggest that inhaled NO can reach the endothelium in the distal microvasculature and alter the response to an oxidative and a nonoxidative activator of endothelium but imparts no antiadhesive effect directly on circulating leukocytes.

Administration, Inhalation↗
PubMed1999

Chronic inflammation upregulates chemokine receptors and induces neutrophil migration to monocyte chemoattractant protein-1.

Monocyte chemoattractant protein-1 (MCP-1) is a CC chemokine that stimulates monocyte recruitment when injected into tissues of healthy animals. However, the function of this chemokine in models with preexisting inflammation is not known. Therefore, MCP-1 was superfused over the mesentery of naive rats or rats with chronic adjuvant-induced vasculitis. MCP-1 elicited increased leukocyte transendothelial migration in adjuvant-immunized rats compared with naive animals. Surprisingly, histology revealed that neutrophils constituted the majority of leukocytes recruited in adjuvant-immunized animals. In vitro, MCP-1 was also able to induce chemotaxis of neutrophils isolated from adjuvant-immunized rats but not from naive rats. Flow cytometry revealed novel expression of the CC chemokine receptors CCR1 and CCR2 on neutrophils from adjuvant-immunized animals. In naive animals, an antibody against CD18 blocked leukocyte adhesion and emigration in response to MCP-1. In adjuvant-immunized animals, leukocyte adhesion was reduced by antibodies against the alpha4-integrin but not by antibodies against CD18. However, the CD18 antibody did block emigration. To our knowledge, this study is the first to show increased sensitivity to a CC chemokine in a model with preexisting inflammation, and altered leukocyte recruitment profiles in response to MCP-1. It also demonstrates that CD18 is required for chemokine-induced leukocyte transendothelial migration, independent of its known role in mediating firm adhesion. J. Clin. Invest. 103:1269-1276 (1999).

Animals↗
PubMed1999

Nitric oxide inhibits microvascular protein leakage induced by leukocyte adhesion-independent and adhesion-dependent inflammatory mediators.

OBJECTIVE: The purpose of this study was to determine whether exogenous nitric oxide could block permeability alterations induced by neutrophil-independent (histamine) and neutrophil-dependent (CINC/gro) inflammatory mediators. METHODS: Intravital microscopy was used in the rat mesentery to examine leukocyte adhesion, transvascular FITC-albumin leakage, and perivascular mast cell activation (ruthenium red uptake) in response to local superfusion with histamine or the chemokine CINC/gro. The effects of the nitric oxide donor spermine-NO, or the cGMP analog 8-Br-cGMP were examined. RESULTS: Histamine superfusion increased vascular protein leakage within minutes, but did not increase firm adhesion above that seen in control preparations. The increase in albumin leakage could be prevented by co-administration of spermine-NO, but was not affected by 8-Br-cGMP. CINC/gro elicited a linear increase in vascular protein leakage and a profound increase in leukocyte adhesion. Treatment with spermine-NO or 8-Br-cGMP significantly attenuated increases in both adhesion and albumin leakage. The actions of spermine-NO and 8-Br-cGMP were not due to mast cell stabilization as neither histamine nor CINC/gro elicited mast cell activation. CONCLUSIONS: This study demonstrates that exogenous nitric oxide and 8-Br-cGMP could block adhesion dependent alterations in vascular permeability induced by CINC/gro, while adhesion-independent alterations in permeability induced by histamine could be blocked by exogenous NO but not 8-Br-cGMP. This suggests that different NO-dependent signalling pathways are important in modulating these two types of vascular protein leakage.

Animals↗
PubMed1998

Differential leukocyte recruitment from whole blood via endothelial adhesion molecules under shear conditions.

The objective of this study was to determine if vascular cell adhesion molecule (VCAM-1), E-selectin, and P-selectin could selectively recruit leukocyte subpopulations, and whether this was affected by shear force or adhesion molecule concentration. Cover slips coated with purified adhesion molecules were incorporated into laminar flow chambers. Whole human blood was perfused for 5 minutes over these cover slips at relative shear forces of 2 to 40 dynes/cm2. Chasing the whole blood with buffer permitted visualization of leukocyte-substratum interactions. Leukocytes were observed to roll on and adhere to VCAM-1 at shears between 2 and 15 dynes/cm2. As assessed by cover slip staining, the majority of these cells were lymphocytes, but eosinophils, monocytes, and, surprisingly, neutrophils were also recruited, events inhibitable by anti-4-integrin antibody (HP1/2). Neutrophils were effectively recruited onto the selectins, with interactions occurring at shears as high as 30 and 40 dynes/cm2 for E- and P-selectin respectively. Eosinophils had high affinity for P- but not E-selectin. Mononuclear cells did not have high affinity for either selectin, but interacted avidly with VCAM-1. Antibodies against P-selectin (G1) and E-selectin (ES-1) completely blocked interactions on these substrates. Reducing the concentration of adhesion molecules did not appreciably change recruitment patterns except for VCAM-1, where neutrophils were no longer recruited. The novel use of whole blood in flow chambers shows a partial selectivity of selectins and VCAM-1 for certain subpopulations of leukocytes under varying physiologic shear conditions.

Blood Physiological Phenomena↗
PubMed1998

The functional paradox of CD43 in leukocyte recruitment: a study using CD43-deficient mice.

Although there is considerable evidence implicating a role for CD43 (leukosialin) in leukocyte cell-cell interactions, its precise function remains uncertain. Using CD43-deficient mice (CD43(-/-)) and intravital microscopy to directly visualize leukocyte interactions in vivo, we investigated the role of CD43 in leukocyte-endothelial cell interactions within the cremasteric microcirculation under flow conditions. Our studies demonstrated significantly enhanced leukocyte rolling and adhesion after chemotactic stimuli in CD43(-/-) mice compared with wild type mice. Using an in vitro flow chamber, we established that the enhanced rolling interactions of CD43(-/-) leukocytes, primarily neutrophils, were also observed using immobilized E-selectin as a substrate, suggesting that passive processes related to steric hindrance or charge repulsion were likely mechanisms. Despite increased adhesion and rolling interactions by CD43(-/-) leukocytes, we uncovered a previously unrecognized impairment of CD43(-/-) leukocytes to infiltrate tissues. Oyster glycogen-induced neutrophil and monocyte infiltration into the peritoneum was significantly reduced in CD43(-/-) mice. In response to platelet activating factor, CD43(-/-) leukocytes were impaired in their ability to emigrate out of the vasculature. These results suggest that leukocyte CD43 has a dual function in leukocyte-endothelial interactions. In addition to its role as a passive nonspecific functional barrier, CD43 also facilitates emigration of leukocytes into tissues.

Animals↗
PubMed1998

Endogenous interleukin-10 regulates hemodynamic parameters, leukocyte-endothelial cell interactions, and microvascular permeability during endotoxemia.

The objective of this study was to determine whether endogenous IL-10 is capable of regulating hemodynamic parameters, leukocyte recruitment, and microvascular permeability in response to endotoxin. Intravital microscopy was used to examine hemodynamic parameters, leukocyte rolling and adhesion, and microvascular permeability in cremasteric postcapillary venules in wild-type mice and in IL-10-deficient (IL-10(-/-)) mice exposed to lipopolysaccharide (LPS). Doses of LPS (3 or 30 microg/kg, IV), which did not reduce blood pressure and minimally altered microvascular hemodynamic factors in wild-type mice, caused significant reductions in these parameters in IL-10(-/-) mice, demonstrating at least a 10-fold increased sensitivity in IL-10(-/-) mice to LPS-induced hemodynamic alterations. Furthermore, in response to LPS (30 microg/kg, IV), leukocyte rolling, adhesion, and fluorescein isothiocyanate-albumin extravasation were increased in the IL-10(-/-) mice. Antibody blockade experiments showed that in both types of mice, leukocyte rolling was mediated by E-selectin and P-selectin. Leukocyte accumulation into other tissues, such as lung, also was enhanced greatly in IL-10(-/-) mice. This was specific to endotoxin, because acute chemotactic stimuli including N-formyl-methionyl-leucyl-phenylalanine elicited similar responses in IL-10(-/-) and wild-type mice. These results suggest that endogenous IL-10 may be a homeostatic regulator of hemodynamic parameters, leukocyte-endothelial cell interactions, and microvascular dysfunction in response to endotoxin and provide potential mechanisms to explain the protective effect of IL-10 against LPS-induced mortality.

Animals↗
PubMed1998

Characterization of Plasmodium falciparum-infected erythrocyte and P-selectin interaction under flow conditions.

Plasmodium falciparum-infected erythrocytes (IRBC) roll on the adhesion molecule P-selectin in vitro under flow conditions that approximate the shear stress in capillary and postcapillary venules in which cytoadherence occurs in vivo. The pathological significance of this adhesive interaction is currently unknown. In this study, we further investigated the molecular interactions between IRBC and P-selectin by using a laminar flow system that allowed for the direct visualization of IRBC-substratum interactions. The results showed that the IRBC-P-selectin interaction was Ca2+-dependent and involved the lectin domain of P-selectin and a sialic acid residue on IRBC. The sialylated P-selectin ligand was trypsin-sensitive, which suggests that it could be part of the parasite antigen PfEMP1 that interacts with CD36 and intercellular adhesion molecule-1 (ICAM-1), but different from a trypsin-resistant IRBC ligand that adheres selectively to chondroitin sulfate A. Studies on the rolling and adhesion of IRBC on activated platelets that express both CD36 and P-selectin showed that inhibition of rolling on P-selectin reduced the adhesion of some clinical parasite isolates to CD36, whereas other parasite isolates appeared to interact directly with CD36. Thus, cytoadherence under physiological flow conditions may be mediated by multiple IRBC ligands that interact with different adhesion molecules in a cooperative fashion. These findings underscore the complexity of the interactions betweeen IRBC and vascular endothelium.

Animals↗
PubMed1998

Inhaled NO as a viable antiadhesive therapy for ischemia/reperfusion injury of distal microvascular beds.

Inhaled nitric oxide (NO) is being used more and more in intensive care units as a modality to improve the outcome of patients with pulmonary complications. Our objective was to demonstrate that inhaled NO could impact upon a distally inflamed microvasculature-improving perfusion, leukocyte adhesive interactions, and endothelial dysfunction. Using intravital microscopy to visualize ischemia/reperfusion of postcapillary venules, we were able to demonstrate that the reduction in perfusion, the dramatic increase in leukocyte rolling, adhesion, and emigration, and the endothelial dysfunction could all be significantly abrogated with 80 ppm, but not 20 ppm inhaled NO. Perfusing whole blood directly over an inert P-selectin and CD18 ligand substratum incorporated in a flow chamber recruited the same number of rolling and adhering leukocytes from NO-ventilated and non-NO-ventilated animals, suggesting that inhaled NO was not directly affecting leukocytes. To demonstrate that inhaled NO was actually reaching the peripheral microvasculature in vivo, we applied a NO synthase inhibitor locally to the feline mesentery and demonstrated that the vasoconstriction, as well as leukocyte recruitment, were essentially abolished by inhaled NO, suggesting that a NO-depleted peripheral microvasculature could be replenished with inhaled NO in vivo. Finally, inhaled NO at the same concentration that was effective in ischemia/reperfusion did not affect vascular alterations, leukocyte recruitment, and endothelial dysfunction associated with endotoxemia in the feline mesentery. In conclusion, our data for the first time demonstrate a role for inhaled NO as a therapeutic delivery system to the peripheral microvasculature, showing tremendous efficacy as an antiadhesive, antivasoconstrictive, and antipermeabilizing molecule in NO-depleted tissues, but not normal microvessels or vessels that have an abundance of NO (LPS-treated). The notion that blood borne molecules have NO carrying capacity is conceptually consistent with our observations.

Administration, Inhalation↗
PubMed1998

A juxtacrine mechanism for neutrophil adhesion on platelets involves platelet-activating factor and a selectin-dependent activation process.

The aim of this study was to identify the molecular mechanisms involved in neutrophil adhesion to immobilized platelets with particular focus on the possible existence of a juxtacrine system for neutrophil-platelet interactions. Platelets were immobilized onto collagen (type I)-coated coverslips that were placed in a flow chamber and neutrophils were perfused across these confluent monolayers at a shear stress of 1 to 4 dynes/cm2. Neutrophils rolled, and a significant proportion (25% to 50%) adhered to platelet monolayers. P-selectin was expressed in very large quantities on the surface of platelets and mediated all of the rolling, whereas the beta2-integrin mediated firm adhesion. An activation mechanism for adhesion was necessary inasmuch as fixed neutrophils continued to roll on immobilized platelets, but did not adhere. Platelets adherent to collagen produced significant levels of platelet-activating factor (PAF). Accordingly, the firm adhesion of neutrophils to platelets was significantly inhibited by a PAF receptor antagonist (WEB 2086). Treatment of only the platelets with acetylhydrolase, which converts membrane-associated PAF to lyso-PAF, prevented 60% of the adhesion. These data suggest that PAF, on the surface of platelets, mediated a significant portion of the adhesive interaction. Addition of some selectin-binding carbohydrates (fucoidan or soluble SLEx analogs but not dextran sulfate) to the platelets caused rolling neutrophils to immediately adhere, an event that was not observed on histamine or thrombin-treated endothelium or P-selectin transfectants. These data support the view that a juxtacrine activation process exists on immobilized platelets for neutrophils. This process can be greatly enhanced on platelets and may involve a signaling mechanism through P-selectin.

Anticoagulants↗
PubMed1998

Postischemic inflammation: a role for mast cells in intestine but not in skeletal muscle.

The objective of this study was to directly study a role for mast cells in ischemia-reperfusion (I/R)-induced mucosal and microvascular dysfunction. I/R was induced in the intestine and skeletal muscle (gastrocnemius and cremaster muscle) of wild-type mice and mast cell-deficient mice (W/Wv). Changes in mucosal permeability (blood-to-lumen clearance of 51Cr-EDTA), leukocyte infiltration (myeloperoxidase activity in the intestine and intravital microscopy in the cremaster muscle), and vascular permeability (tissue wet-to-dry weight ratio and FITC-albumin leakage) were measured as indexes of tissue dysfunction. In wild-type animals, intestinal I/R induced a significant increase in mucosal permeability, leukocyte infiltration, and vascular permeability. Mast cell-deficient animals were completely protected from I/R-induced mucosal dysfunction. However, skeletal muscle I/R induced a significant increase in leukocyte infiltration, FITC-albumin leakage, and edema formation to the same degree in both wild-type and mast cell-deficient animals. These data suggest that mast cells may be important mediators of I/R-induced mucosal and microvascular dysfunction in the intestine but not of microvascular dysfunction in skeletal muscle.

Animals↗
PubMed1998

Preconditioning and adenosine in I/R-induced leukocyte-endothelial cell interactions.

Recently, it was reported that preconditioning reduced leukocyte adhesion following ischemia-reperfusion (I/R). We further examined the effects of preconditioning and adenosine not only on neutrophil adhesion but also on neutrophil rolling and vascular dysfunction. Intravital microscopy revealed a decrease in neutrophil rolling velocity; a profound increase in neutrophil rolling, adhesion, and microvascular dysfunction; and a reduction in venular shear rates associated with 60 min ischemia and 60 min reperfusion in the feline mesentery. Preconditioning (5 min ischemia/10 min reperfusion) prevented subsequent I/R-induced slow neutrophil rolling, neutrophil adhesion, and microvascular dysfunction but did not affect the flux of rolling neutrophils. Adenosine deaminase A1 and A2 adenosine-receptor antagonists had only minor effects on the preconditioning responses. Pretreatment of vessels with exogenous adenosine reduced neutrophil adhesion and microvascular permeability and improved neutrophil rolling velocity and shear forces associated with I/R, but the flux of rolling neutrophils was not affected. Finally, in vitro experiments revealed that adenosine had absolutely no direct effect on neutrophil-endothelial cell interactions. In conclusion, our data suggest that adenosine plays only a minor role in preconditioned vessels and that adenosine per se may not directly affect neutrophil-endothelial cell interactions.

Adenosine↗
PubMed1998

Anaphylaxis-induced mesenteric vascular permeability, granulocyte adhesion, and platelet aggregates in rat.

This study investigates the response of small venules to IgE-dependent, antigen-mediated mast cell activation. Intravital microscopy was utilized to visualize 25- to 40-micron mesenteric venules, mast cell degranulation (on-line detection), vascular permeability changes (albumin leakage), leukocyte adhesion, and the formation of platelet aggregates in rats sensitized with 10 microg of intraperitoneal egg albumin (EA) in saline- or sham-sensitized (saline alone) rats. Sensitized rats challenged with EA (1 mg/ml superfusing mesentery), but not sensitized rats challenged with BSA or sham-sensitized rats challenged with EA, exhibited mast cell degranulation with significant time-dependent increases in vascular permeability (inhibited by diphenhydramine, salbutamol, and indomethacin), leukocyte adhesion (inhibited by Web-2086), and the formation of cellular aggregates (platelet), which were associated with intermittent obstruction of venular flow. Anti-platelet antibody, but not anti-neutrophil antibody or fucoidin (selectin antagonist), prevented platelet aggregate formation. Compound 48/80-induced mast cell degranulation caused similar changes in permeability (via different mediators) and leukocyte adhesion but did not induce platelet aggregation. EA-induced platelet aggregation was not inhibited by any of the mediators tested, and platelets isolated from sensitized rats failed to aggregate in response to direct EA challenge, suggesting release of an unidentified inflammatory mediator as the factor initiating platelet aggregation.

Albuterol↗
PubMed1998

A role for mast cells in the development of adjuvant-induced vasculitis and arthritis.

The objective of this study was to characterize the role of mast cells in the development of vasculitis and joint swelling in adjuvant-immunized rats. Leukocyte trafficking within mesenteric venules (rolling and adhesion) and mast cell activation (ruthenium red uptake) were examined in vivo. Elevated leukocyte trafficking was observed by 4 days after immunization, whereas joint swelling developed between days 10 and 12. Perivascular mast cells took up ruthenium red and appeared activated by electron microscopy at 4 but not 12 days after immunization. Treatment with the mast cell stabilizer cromolyn on days 1 to 4 after immunization blocked ruthenium red uptake at day 4 and reduced leukocyte rolling and adhesion by approximately 50%. This treatment also reduced rolling, adhesion, and joint swelling at day 12 by approximately 50%. Cromolyn treatment over days 9 to 12 reduced joint swelling but increased leukocyte emigration into the mesentery. Peritoneal mast cells isolated 4 days after immunization elicited significant neutrophil chemotaxis in vitro, whereas day 12 mast cells did not. Mast cell activation and vasculitis were absent in adjuvant-resistant Fisher/344 rats. These data suggest that mast cells play an early role in the initiation of vasculitis and may function by day 12 to limit infiltration of leukocytes from the vasculature. In the joint, however, mast cells appear to contribute to inflammation at early as well as later time points.

Animals↗
PubMed1998

Antithrombin and ischemia/reperfusion.

Acute inflammation, a localized response that occurs in various diseases, is characterized by neutrophil infiltration into tissues. This process requires neutrophils to initially tether and roll along the endothelium of postcapillary venules before undergoing firm adhesion and emigration out of the vasculature into the tissues. Recently, thrombin has been implicated at multiple sites in the inflammatory cascade, and may represent an important link between inflammation and thrombosis. Our recent studies demonstrate that thrombin is an important mediator of neutrophil-dependent injury in ischemia-reperfusion injury. Furthermore, antithrombin concentrate may be therapeutically efficacious in ischemia-reperfusion injury, as it is capable of attenuating the thrombin-mediated effects on neutrophil-endothelial interactions.

Animals↗