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P Kubes

Publications and source records attributed to P Kubes.

At least 73 records · Page 4Linked to original sources
PubMed1998

An absolute requirement for P-selectin in ischemia/reperfusion-induced leukocyte recruitment in cremaster muscle.

OBJECTIVE: To systematically examine a role for P-selectin in a model of striated muscle ischemia/reperfusion (I/R). METHODS: Ischemia was induced in the cremaster muscle of mice by occluding the main feeding arteriole for 30 minutes. Blood flow was then restored to allow for 60 minutes of reperfusion and leukocyte kinetics were assessed during the control period (before I/R) and at 5, 30, and 60 minutes of reperfusion. To study a role for P-selectin in this model, three different approaches were used: Wild-type animals received fucoidin (10 mg/kg, i.v.), an anti-P-selectin antibody (RB40.34; 20 mg/animal, i.v.) at 25 minutes of ischemia, or I/R was induced in P-selectin-deficient mice. RESULTS: Ischemia/reperfusion induced a rapid and significant increase in leukocyte rolling, adhesion, and emigration in wild-type mice. The I/R-induced increase in leukocyte rolling was transient, inasmuch as it was reduced by approximately 50% at 30 minutes of reperfusion, and returned to control levels by 60 minutes. Both fucoidin and an anti-P-selectin antibody completely prevented the I/R-induced increase in leukocyte rolling. The P-selectin-deficient animals exhibited absolutely no baseline leukocyte rolling, adhesion, or emigration. Furthermore, I/R did not induce any increase in leukocyte recruitment in the P-selectin-deficient animals over the first 60 minutes of reperfusion. CONCLUSION: The results from this study clearly illustrate that P-selectin is absolutely critical in both baseline and I/R-induced leukocyte infiltration in the murine-striated muscle.

Animals↗
PubMed1997

Differential roles of selectins and the alpha4-integrin in acute, subacute, and chronic leukocyte recruitment in vivo.

Adhesion blocking mAbs specific for rat P-, E-, and L-selectin and the alpha4-integrin were used to characterize leukocyte recruitment mechanisms in models of LTC4 (acute), LPS (subacute), and adjuvant-induced (chronic) inflammation. Intravital microscopy was employed to measure leukocyte rolling and adhesion in rat mesenteric venules. Superfusing the mesentery with 20 nM LTC4 elicited an increase in leukocyte rolling (66.8 +/- 3.8 vs 18.2 +/- 3.2 cells/min control) that was completely eliminated by an anti-rat P-selectin mAb. Superfusion with 1 microg/ml LPS induced a significant increase in leukocyte rolling within 15 min (73 +/- 8 vs 33 +/- 6 cells/min control). Rolling increased further starting at 105 min and peaked by 150 min (141 +/- 23 cells/min). LPS-induced leukocyte rolling was eliminated during the first 90 min by the P-selectin mAb. The later increase in leukocyte rolling was not prevented by a second treatment with P-selectin mAb or a function-blocking mAb against rat E-selectin. This later phase of leukocyte rolling was blocked by treatments with mAbs against either the alpha4-integrin or L-selectin. Twelve days following Mycobacterium butyricum immunization, 300 to 500 rolling cells/min were observed. This could be reduced approximately 50 to 60% by mAb against either the alpha4-integrin or L-selectin. The combination of both mAbs eliminated approximately 90% of rolling. Neither the P- nor E-selectin mAbs reduced rolling in this chronic inflammatory model. This study highlights differences in leukocyte adhesive mechanisms elicited by different stimuli and at different time points within the same vascular bed.

Animals↗
PubMed1997

Antithrombin III prevents and rapidly reverses leukocyte recruitment in ischemia/reperfusion.

BACKGROUND: P-selectin has recently been shown to be essential for leukocyte rolling after the reperfusion of ischemic mesentery. However, the mediators responsible for neutrophil rolling in ischemic microvessels remain entirely unclear. METHODS AND RESULTS: Intravital microscopy was used to examine leukocyte kinetics in a feline mesentery ischemia/reperfusion model. Sixty minutes of ischemia followed by reperfusion caused a profound increase in leukocyte rolling and adhesion. Pretreatment with the endogenous antithrombotic agent antithrombin III (ATIII) infused as a bolus (250 U/kg) reduced neutrophil rolling and adhesion to preischemic levels during reperfusion. No effect was seen with heat-inactive ATIII. Importantly, ATIII posttreatment also significantly reduced neutrophil rolling and adhesion during reperfusion, suggesting that ATIII can reverse the leukocyte recruitment response induced by ischemia/reperfusion. Vascular permeability was also reduced by 50% after ATIII administration. To determine whether ATIII could reverse thrombin-induced rolling directly, neutrophil rolling was performed on human endothelium in flow chambers. Indeed, thrombin-induced rolling, but not histamine-induced rolling, could be rapidly reversed with ATIII on endothelium, suggesting that ATIII affects thrombin rather than directly affecting neutrophils or the endothelium. CONCLUSIONS: This study demonstrates for the first time that thrombin plays an important role in ischemia-induced leukocyte rolling and adhesion and that ATIII can be used therapeutically postreperfusion to attenuate the leukocyte recruitment response in inflammation without the nonspecific effects associated with anti-adhesion molecule therapy.

Animals↗
PubMed1997

A minimal role for selectins in the recruitment of leukocytes into the inflamed liver microvasculature.

A two-step paradigm for leukocyte recruitment has been established in a number of tissues including the mesentery, skin, and muscle, and necessitates an initial rolling step via the selectins before firm leukocyte adhesion via the integrins. In view of the many inflammatory diseases that involve the liver, we investigated the importance of rolling and the selectins in the hepatic microvasculature and compared the responses to that of the commonly used mesentery or cremaster microvasculature. We visualized the liver microvasculature using intravital microscopy and we determined that within the liver the majority of leukocytes adhere within the sinusoids (80%) in response to a chemotactic stimulus such as FMLP (20% in postsinusoidal venules) whereas leukocytes adhere exclusively within postcapillary venules in tissue like the mouse cremaster. In the sinusoids, the adhesive response to FMLP is not dependent upon selectins inasmuch as adhesion was not reduced in the sinusoidal vessels of P-selectin-deficient mice or E-selectin/P-selectin- deficient animals in the presence or absence of L-selectin antibody. No rolling or adhesion was detected in response to FMLP in the selectin-deficient cremaster microvasculature. Immunoneutralization of selectins with fucoidan in wildtype mice eliminated rolling and adhesion in the cremaster but failed to affect adhesion in the liver sinusoids in response to FMLP. More long-term leukocyte recruitment with lipopolysaccharide (4 h) was also impaired in the cremaster but not the liver microvasculature in selectin-deficient animals. Leukocyte adhesion in the sinusoids was reduced in P-selectin-deficient mice also lacking intercellular adhesion molecule-1 (ICAM-1). This study for the first time demonstrates that selectins are not an essential step for leukocyte recruitment into the inflamed liver microvasculature.

Animals↗
PubMed1997

Neutrophils can adhere via alpha4beta1-integrin under flow conditions.

In this study we investigated the possibility that an alternative pathway exists for neutrophil recruitment, namely an alpha4beta1-dependent pathway. A parallel plate chamber was used to investigate whether neutrophils could tether, roll, and adhere to tumor necrosis factor alpha (TNF alpha)-stimulated endothelium via alpha4beta1. alpha4beta1-integrin was induced on neutrophils using dihydrocytochalasin B and either an endogenous (endothelial-derived) chemotactic agent or an exogenous chemotactic molecule. alpha4beta1-expressing neutrophils could stably adhere under shear force (2 dyne/cm2) to TNF alpha-stimulated endothelium independent of the beta2-integrin. The firm adhesion was entirely abolished by antibodies directed against either the alpha4 or beta1-integrin subunits. However, the rolling interaction was not dependent on alpha4beta1 but was abolished by antiselectin therapy. Neutrophils expressing alpha4beta1 could also tether to the endothelium in the presence of antiselectin therapy, but at shear stresses less than 2 dyne/cm2. alpha4beta1-expressing neutrophils also tethered to and stably adhered (no rolling) to VCAM-1- but not to ICAM-1-transfected L cells. The interaction only occurred at shear stress less than 2 dyne/cm2. A cell line (Ramos) known to express high quantities of alpha4beta1-integrin interacted with VCAM-1-transfected L cells at very similar shear conditions. alpha4beta1-expressing neutrophils were also able to adhere to a second alpha4-integrin ligand, fibronectin; however, this interaction only occurred under static conditions. These data suggest that, under certain conditions, neutrophils can adhere independently of the beta2-integrin pathway and adhere via the alpha4beta1-integrin. This study refutes the concept that alpha4beta1-integrin adhesion is restricted to mononuclear leukocytes and is not functional on human neutrophils.

Animals↗
PubMed1997

Promiscuity of clinical Plasmodium falciparum isolates for multiple adhesion molecules under flow conditions.

The central pathologic process in severe Plasmodium falciparum malaria is the cytoadherence of parasitized erythrocytes to capillary and postcapillary venular endothelium, with resultant tissue hypoxia, metabolic disturbances, and multiorgan dysfunction. The molecular basis of this process has been studied extensively using static adhesion assays. In the present study, we determined whether infected red blood cells (IRBC) from clinical parasite isolates would roll and adhere on CD36, ICAM-1, E-selectin, P-selectin, and VCAM-1 using a laminar flow system that allowed for the direct visualization of IRBC-substratum interactions. The results indicate that IRBC could tether and roll on CD36, ICAM-1, P-selectin, and VCAM-1 in a shear-dependent fashion, but significant adhesion was restricted to CD36. There was no interaction with E-selectin. When both CD36 and ICAM-1 were expressed on the same cellular substratum such as C32 melanoma cells, adhesion was significantly greater than when CD36 was present alone. The adhesive interactions were different from those between leukocytes and the same adhesion molecules. Furthermore, IRBC rolling on P-selectin and VCAM-1 was not inhibitable by Abs that entirely prevented leukocyte-receptor interactions. These findings suggest that cytoadherence under physiologic conditions may be a multistep process similar to that involved in the recruitment of a number of different cell types. Further elucidation of the molecular basis of these novel interactions is crucial for the development of therapeutic interventions aimed at inhibiting or reversing the process.

Animals↗
PubMed1997

Tumor necrosis factor-alpha induces leukocyte recruitment by different mechanisms in vivo and in vitro.

It is well established that E-selectin is the endothelial adhesion molecule that is primarily responsible for mediating leukocyte rolling on TNF-alpha-stimulated cultured endothelial cells. Despite this, few studies in in vivo inflammatory models have observed reduced leukocyte accumulation using mAbs against E-selectin. The objective of this study was to compare the function of E-selectin on endothelial cells in vitro with its role in TNF-alpha-induced leukocyte recruitment in vivo using EL246, a mAb that blocks the function of E-selectin on activated feline endothelial cells. In vitro experiments using feline endothelial cells showed that EL246 functionally inhibits E-selectin-dependent leukocyte recruitment induced by TNF-alpha, without affecting the function of other rolling mechanisms. Intravital microscopy of single 25- to 40-microm venules in the feline mesentery was then used to examine leukocyte rolling and adhesion in response to superfusion with TNF-alpha. TNF-alpha treatment significantly increased the number of both rolling and adherent leukocytes and significantly decreased leukocyte rolling velocity. Treatment with EL246 (1 mg/kg), either i.v. at the start of the TNF-alpha protocol or directly into the superior mesenteric artery after 3 h of TNF-alpha treatment, had no effect on leukocyte rolling, adhesion, or rolling velocity. However, treatment with the selectin-binding carbohydrate, fucoidan, reduced leukocyte rolling to below baseline levels. These results suggest that in contrast to its prominent role on cultured endothelial cells, E-selectin does not contribute to leukocyte recruitment in TNF-alpha-stimulated feline mesenteric venules in vivo.

Animals↗
PubMed1997

The association between alpha4-integrin, P-selectin, and E-selectin in an allergic model of inflammation.

In this study, we examined the relationship between the endothelial selectins (P-selectin and E-selectin) and whether they are critical for alpha4-integrin-dependent leukocyte recruitment in inflamed (late phase response), cremasteric postcapillary venules. Animals were systemically sensitized and 2 wk later challenged intrascrotally with chicken ovalbumin. Leukocyte rolling flux, adhesion, and emigration were assessed at baseline and 4 and 8 h postantigen challenge. There was a significant increase in leukocyte rolling flux, adhesion, and emigration in sensitized and challenged mice at both 4 and 8 h. At 8 h, the increase in leukocyte rolling flux was approximately 50% inhibitable by an anti-alpha4-integrin antibody, 98% inhibitable by fucoidin (a selectin-binding carbohydrate), and 100% inhibitable by an anti-P-selectin antibody. P-selectin-deficient animals displayed no leukocyte rolling or adhesion at 8 h after challenge. However, at 8 h there were many emigrated leukocytes in the perivascular space suggesting P-selectin-independent rolling at an earlier time point. Indeed, at 4 h postantigen challenge in P-selectin-deficient mice, there was increased leukocyte rolling, adhesion, and emigration. The rolling in the P-selectin-deficient mice at 4 h was largely alpha4-integrin dependent. However, there was an essential E-selectin-dependent component inasmuch as an anti-E-selectin antibody completely reversed the rolling, and in E-selectin and P-selectin double deficient mice rolling, adhesion and emigration were completely absent. These results illustrate that P-selectin underlies all of the antigen-induced rolling with a brief transient contribution from E-selectin in the P-selectin-deficient animals. Finally, the antigen-induced alpha4-integrin-mediated leukocyte recruitment is entirely dependent upon endothelial selectins.

Animals↗
PubMed1997

The role of shear forces in ischemia/reperfusion-induced neutrophil rolling and adhesion.

Intravital microscopy was used to examine the role of reduced shear forces on neutrophil-endothelium interactions in single 25-40 microm diameter vessels in the feline postischemic mesenteric microvasculature. Neutrophil rolling, neutrophil adhesion, and microvascular permeability alterations were determined in vessels exposed to ischemia/reperfusion in untreated animals and in cats that received feline plasma directly into the superior mesenteric artery to increase intestinal blood flow and venular shear rates. Ischemia, followed by reperfusion, caused a profound increase in venular shear forces during the initial hyperemic response, which then decreased to below control values by 10 min of reperfusion and to less than 50% of control by 60 min of reperfusion. Associated with the decrease in blood flow was a profound increase in neutrophil rolling and neutrophil adhesion and an increase in microvascular permeability. Also, leukocyte rolling velocity decreased dramatically to 10-20% of control values during the first 10 min of reperfusion. Infusion of autologous plasma into the intestinal vasculature to maintain the shear forces at control levels during reperfusion did not affect the flux of rolling neutrophils. The rolling velocity of the neutrophils was not increased despite dramatically improved shear rates. Improved shear rates did reduce the number of adherent cells, resulting in less vascular dysfunction. The reduction in shear forces through inflamed microvessels does not contribute to the increased leukocyte rolling flux but is an essential, permissive component for neutrophil adhesion and subsequent vascular dysfunction in postischemic microvasculature.

Animals↗
PubMed1997

Plasma L-arginine concentrations in premature infants with necrotizing enterocolitis.

OBJECTIVE: To determine whether L-arginine concentrations (the substrate for nitric oxide synthesis) are lower in premature infants in whom necrotizing enterocolitis (NEC) develops than in unaffected infants. METHODS: We measured arginine and nutritional intake, plasma arginine, glutamine, total amino acids, and ammonia concentrations in 53 premature infants (mean gestational age +/- SD: 27 +/- 1.7 weeks) at risk of NEC. Measurements were done on days 3, 7, 14 and 21 and just before treatment in infants with NEC. RESULTS: Necrotizing enterocolitis developed in 11 infants between postnatal days 1 and 26. On day 3, plasma arginine concentrations were decreased compared with normal published values (mean +/- SE, 41 mumol/L +/- 4). Arginine concentrations increased with day of life of measurement (p < 0.001) and arginine intake (p < 0.001). Plasma arginine concentrations were significantly lower at the time of diagnosis in infants with NEC compared with control subjects, even after adjusting for arginine intake and day of life (p = 0.032). Plasma glutamine and total amino acid concentrations were not significantly different in infants with NEC compared with control subjects. Plasma ammonia concentrations were elevated on day 3 (mean +/- SE, 72 +/- 3.3 mumol/L) and decreased with postnatal age (p < 0.001) and increasing plasma arginine concentrations (p < 0.001). CONCLUSION: Plasma arginine concentrations are decreased at the time of diagnosis in premature infants with NEC. The potential benefit of arginine supplementation in the prevention of the disease deserves evaluation.

Age Factors↗
PubMed1997

Inducible nitric oxide synthase plays a critical role in resolving intestinal inflammation.

BACKGROUND & AIMS: Overproduction of nitric oxide by inducible nitric oxide synthase (iNOS) has been proposed as a pathogenic factor in colitis. The objective of this study was to examine the role of iNOS using iNOS-deficient mice in experimental colitis. METHODS: Colitis was induced by intrarectal instillation of 3% acetic acid and assessed for neutrophilic infiltration and intestinal injury over 7 days. iNOS messenger RNA expression was also measured. RESULTS: At 24 hours, acetic acid induced a mild colitis in wild-type mice. An increase in neutrophil infiltration and tissue edema was also observed. In the iNOS-deficient mice, a twofold increase in macroscopic damage was observed. Neutrophil infiltration and tissue edema were similar to those in wild-type animals at this time point. Although inflammation in wild-type mice had resolved by 7 days, a sevenfold increase in damage score and elevated myeloperoxidase level were still evident in iNOS-deficient mice. A striking increase in the message for iNOS was observed in inflamed wild-type mice at 24 hours and was still present at 72 hours. No message was found in iNOS-deficient mice. CONCLUSIONS: Induction of iNOS seems to be a critical protective response to injury in intestinal inflammation possibly by reducing leukocytic infiltration.

Animals↗
PubMed1997

Inducible nitric oxide synthase-deficient mice have enhanced leukocyte-endothelium interactions in endotoxemia.

Nitric oxide (NO) from constitutive NO synthase (NOS) has been postulated to be a homeostatic regulator of leukocyte-endothelial cell interactions. By contrast, the inducible NO synthase (iNOS) isoform has been invoked as a potential pathogenic enzyme in numerous inflammatory diseases. The objective of this study was to determine whether the iNOS isoform is also capable of functioning as a regulator of leukocyte recruitment. Mice received endotoxin (LPS, 30 microg/kg, i.v.); 2-4 h later, intravital microscopy was used to examine leukocyte rolling and adhesion in postcapillary venules of the cremaster muscle and the sinusoids and postsinusoidal venules of the hepatic microcirculation. Leukocyte recruitment into the lung was also examined. RT-PCR confirmed that this treatment induced iNOS mRNA expression in wild-type mice as early as 2 h after LPS treatment. Between 2 and 4 h after LPS administration, the number of rolling and adherent leukocytes in cremasteric postcapillary venules and of adherent cells in liver postsinusoidal venules of iNOS-deficient mice were significantly higher than in wild-type mice. Leukocyte accumulation in the lung (measured by myeloperoxidase assay) was also significantly elevated in iNOS-deficient animals. These effects could not be attributed to differences in systemic blood pressure, shear rates, circulating leukocyte numbers, or baseline levels of rolling and adhesion because these parameters were not different between the two groups. To establish whether the differences in leukocyte recruitment were related to the leukocytes per se, perfusion of iNOS+/+ or iNOS-/- septic blood over purified E-selectin (using parallel plate flow chambers) revealed much larger recruitment of iNOS-/- leukocytes. These results suggest that iNOS induced in response to LPS releases NO that is capable of reducing leukocyte accumulation by affecting leukocytes directly and raises the possibility that induction of iNOS is a homeostatic regulator for leukocyte recruitment.

Analysis of Variance↗
PubMed1997

Endogenous but not exogenous nitric oxide decreases TNF-alpha-induced leukocyte rolling.

Inhibition of nitric oxide (NO) synthesis in mesenteric microvessels increases leukocyte rolling. The objective of this study was to determine whether inducible NO synthase (iNOS) can modulate tumor necrosis factor-alpha (TNF-alpha)-induced leukocyte rolling. Leukocyte rolling was examined using intravital microscopy of TNF-alpha-treated feline mesenteric microvasculature. Leukocyte rolling increased progressively over 3 h of TNF-alpha treatment. Pretreatment with the selective iNOS inhibitor aminoguanidine further doubled TNF-alpha-induced leukocyte rolling. Aminoguanidine alone did not affect baseline blood pressure or leukocyte kinetics. However, in the same animals NG-nitro-L-arginine methyl ester caused a rapid increase in blood pressure, confirming that constitutive NOS activity persisted in aminoguanidine-treated animals. Furthermore, aminoguanidine did not affect leukocyte rolling in an acute model of leukocyte recruitment (ischemia/reperfusion), suggesting that the exacerbated rolling induced by aminoguanidine with TNF-alpha as a stimulus was not a nonspecific effect. Addition of the NO donor spermine-NO had no effect on TNF-alpha-associated leukocyte rolling. These data raise the possibility of a physiological role for the increased production of NO from iNOS, i.e., regulation of leukocyte rolling and potentially the inflammatory response.

Animals↗
PubMed1997

Emigrated rat neutrophils adhere to cardiac myocytes via alpha 4 integrin.

Previous work has shown that neutrophils isolated from whole blood adhere to cardiac-myocytes via CD18 (beta 2 integrin) to cause injury to the heart cells. In vitro, we have found that upon endothelial transmigration, neutrophils can also express alpha 4 beta 1; however, whether this contributes to neutrophil adhesion to parenchymal cells remains entirely unknown. Unstimulated and tumor necrosis factor-alpha-stimulated rat cardiac myocytes adherent to gelatin-coated coverslips supported N-formyl-Met-Leu-Phe (fMLP)-induced neutrophil (isolated from whole blood) adhesion entirely via CD18 (blocked with monoclonal antibody [mAb] WT-3). Emigrated neutrophils spontaneously adhered to cardiac myocytes also entirely via CD18. However, if fMLP was used to restimulate emigrated neutrophils, the adhesion to cardiac myocytes was entirely independent of CD18. Although an anti-alpha 4 integrin antibody (mAb TA-2) alone did not reduce the emigrated neutrophil-myocyte interaction, dual administration of TA-2 and WT-3 reduced adhesion by 81%. alpha 4 integrin was expressed in small amounts on the surface of circulating neutrophils, increased following transmigration, and then increased > 5-fold after restimulation of these emigrated neutrophils. In the presence of the anti-CD18 antibody, a fibronectin fragment (FN-40) but not a vascular cell adhesion molecule-1 antibody (mAb 5F10) inhibitied neutrophil-myocyte interactions by 80%. Similar results were seen when the rat chemokine CINC-gro was used instead of fMLP, suggesting that the alpha 4-dependent adhesion was not specific to fMLP. These data demonstrate that alpha 4 integrin can be physiologically induced to increase in number and avidity after neutrophil emigration and that this adhesion molecule can cause firm adhesion to fibronectin on parenchymal cells, including rat cardiac myocytes.

Animals↗
PubMed1996

The alpha 4-integrin supports leukocyte rolling and adhesion in chronically inflamed postcapillary venules in vivo.

A role for the alpha 4-integrin (alpha 4 beta 1 or alpha 4 beta 7), has been implicated in the recruitment of peripheral blood mononuclear cells (PBMCs) to sites of inflammation. However, the adhesive interactions (i.e., tethering, rolling, and adhesion) mediated by the alpha 4-integrin have not been characterized in vivo. The objective of this study was to establish a model wherein postcapillary venules were chronically inflamed, and then use intravital microscopy to identify the adhesive interactions mediated by the alpha 4-integrin in vivo. Between 4 and 20 d after immunization with Mycobacterium butyricum, animals developed a systemic vasculitis characterized by large increases in the numbers of rolling and adhering leukocytes within mesenteric venules. The selectins could only account for approximately 50% of the leukocyte rolling whereas the remaining cells rolled exclusively via the alpha 4-integrin. Anti-alpha 4 therapy also eliminated the increase in leukocyte adhesion observed in this model, whereas selectin therapies and an anti-CD18 (beta 2-integrin) monoclonal antibody (mAb) did not reduce adhesion. A serum against polymorphonuclear leukocytes (PMNs) was used to confirm that a significant proportion of rolling cells, and most of the adhering cells were PBMCs. Sequential treatment with anti-PMN serum and the anti-alpha 4 mAb demonstrated that alpha 4-dependent rolling was distinct from PMN rolling populations. Initial leukocyte tethering via the alpha 4-integrin could not be demonstrated in this model, whereas L-selectin did support leukocyte tethering. These data suggest that the alpha 4-integrin can mediate both rolling and adhesion in the multistep recruitment of PMBCs in vivo, and these interactions occur independently of the selectins and beta 2-integrins.

Animals↗
PubMed1996

Nitric oxide inhibits numerous features of mast cell-induced inflammation.

BACKGROUND: We previously reported that mast cell degranulation causes histamine and P-selectin-dependent leukocyte rolling and platelet-activating factor (PAF)- and CD18-associated leukocyte adhesion, whereas others have reported serotonin-induced edema formation. The purpose of the present study was to determine whether nitric oxide (NO) could inhibit the mast cell-induced multistep recruitment of leukocytes and the associated microvascular dysfunction in single inflamed venules. METHODS AND RESULTS: Intravital fluorescence microscopy was used to demonstrate increased leukocyte rolling and adhesion and increased albumin extravasation in single 25- to 40-microns venules that were treated with the mast cell-degranulating agent compound 48/80 (CMP 48/80). The mast cell-induced histamine-dependent rolling and PAF-dependent adhesion were completely inhibited by the addition of the NO donor spermine NO. However, spermine NO did not directly inhibit histamine-induced leukocyte rolling and only partly affected PAF-induced leukocyte adhesion. Compound 48/80-activated mast cells evoked a significant increase in PAF-dependent neutrophil adhesion in vitro. Spermine-NO prevented the mast cell-dependent neutrophil adhesion but failed to affect direct adhesion with PAF. The mast cell-induced albumin leakage was also inhibited by the NO donor. CONCLUSIONS: Taken together, these results suggest that exogenous NO can modulate leukocyte recruitment and microvascular permeability alterations elicited by mast cell activation and raises the possibility that the use of NO donors may be a reasonable therapeutic approach to reducing mast cell-dependent inflammation.

Animals↗