Plasma Exudation Research Articles

Acute allergic responses induce a prompt luminal entry of airway tissue eosinophils.

Traditionally, traffic and activation of eosinophils in asthmatic airways are thought to take place during the late-phase allergic reaction. The present study tests the hypothesis that when eosinophils are present in the tissue before allergen exposure, as in chronically inflamed asthmatic airways, acute anaphylactic reactions initiate an eosinophil response. Using a guinea-pig allergic model, where eosinophilia is present at baseline conditions, the traffic of resident eosinophils was examined in vivo immediately after allergen challenge. By 2 min after challenge, eosinophils had moved up to apical epithelial positions. Within 10 min, a marked migration of eosinophils into the airway lumen was demonstrated. Along with the allergen-induced egression of eosinophils, acute luminal entry of plasma proteins and eotaxin occurred. Eosinophil egression was effectively inhibited by the antiexudative drug formoterol, whereas the proexudative drug bradykinin could in naive animals evoke a prompt luminal entry of eosinophils. In conclusion, the present study demonstrates that acute allergic reactions initiate a prompt transepithelial migration of resident eosinophils. Our data further suggest that this response in part is initiated by the plasma exudation response, which may alter the transepithelial gradient of eosinophil chemoattractants including eotaxin. We propose that prompt eosinophil response is a significant component of the acute phase of allergic reactions when occurring in airways where these cells are already present in the mucosa.

Cysteinyl leukotrienes as common mediators of asthma and allergic disease

SummaryThe cysteinyl leukotrienes (CysLTs) induce a number of pro‐inflammatory effects including smooth muscle contraction, an increase in blood flow, plasma exudation, mucous secretion, and activation of inflammatory cells. They play a key role in asthma and allergy, and can be recovered from different body fluids (e.g. bronchoaleveolar or nasal lavage and urine) during allergen‐induced hypersensitivity reactions. The advent of antileukotriene agents (i.e. leukotriene receptor antagonists or leukotriene synthesis inhibitors) has helped clarify how the different mechanisms contribute to inflammation, as well as offer new treatment options for both asthma and allergy. It is now clear that the release of leukotrienes is the final common path for the many different factors causing airway obstruction and inflammation. In asthma, clinical studies have shown that treatment with antileukotrienes can improve pulmonary function, alleviate symptoms, reduce asthma exacerbations, and decrease the need for bronchodilator therapy. Similarly, in patients with allergic rhinitis, improvements have been seen in nasal symptoms, eye symptoms and quality of life. Antileukotrienes provide a new opportunity for simultaneous management of allergic diseases of the upper and lower respiratory tract, and are a rational treatment approach to the concept of ‘one airway’ disease. In future, their utility may also extend to inflammatory disorders of other organ systems (e.g. skin).

Elicitation of the allergic reaction in beta-lactoglobulin-sensitized Balb/c mice: biochemical and clinical manifestations differ according to the structure of the allergen used for challenge.

Mouse models of allergy are used to study the mechanisms of induction and perpetuation of bronchopulmonary hyper-reactivity (BHR) as related to eosinophils and specific IgE. Our aim was to adapt the current model for the study of bovine beta-lactoglobulin (BLG), a major cow's milk allergen, and to further analyse the mechanisms of the acute and late allergic reaction. Female Balb/c mice were sensitized intraperitoneally with BLG and the influence of the adjuvant and of the BLG dose on the IgE response was analysed, IgE and IgG1 epitopes being characterized. Once optimized, this model was applied to the study of the active phase of allergy in the respiratory tract after a single airway challenge using native or denatured BLG, which contains only linear epitopes. An immediate allergic reaction was characterized by the rapid release of histamine into the bronchoalveolar lavage fluids. Prostaglandin (PG)D2 was only present when the standard histamine-releasing agent compound 48/80 or denatured BLG were used as triggers, whereas native BLG induced leukotriene release. Twenty-four hours after challenge, BHR, eosinophil influx, IL-4 and IL-5 production, plasma exudation and mucus production were very much increased, differently depending on the allergen structure, and indicated the occurrence of the late allergic reaction. Our results show that the murine model can be used to study the mechanisms of allergy to clinically relevant antigens, such as those contained in cow's milk. The acute allergic reaction, which depends on the structural feature of the allergen, is composed of two distinct pathways characterized by peptido-leukotrienes or PGD2 production, which may result from distinct activation intensities of mast cells, leading to distinct late reactions. This study thus demonstrates a clear link between the structural feature of a protein, and the physiopathology of the experimental asthmatic reaction.

Steroid‐sensitive indices of airway inflammation in children with seasonal allergic rhinitis

Previous studies involving adults have demonstrated that airway glucocorticosteroids inhibit plasma exudation and eosinophil activity in allergic rhinitis. This study explores the possibility that plasma exudation, exudative responsiveness, and the occurrence of eosinophil activity-related proteins are glucocorticosteroid-sensitive nasal mucosal indices in allergic children. Using a placebo-controlled, parallel-group design effects of nasal budesonide (64 microg per nasal cavity b.i.d) were determined in children with seasonal allergic rhinitis. Nasal lavage fluid levels of eotaxin, eosinophil cationic protein (ECP), and alpha2-macroglobulin, indicating plasma exudation, were determined, the latter with and without challenge with topical histamine. Nasal lavage fluid levels of alpha2-macroglobulin and ECP increased significantly during the pollen season, and the acute plasma exudation response to histamine was significantly greater during than outside the season. There was a trend towards a seasonal increase in nasal lavage fluid levels of eotaxin. Budesonide significantly inhibited the seasonal increase in alpha2-macroglobulin as well as the exudative hyperresponsiveness to histamine. Any tendency of increases in mucosal output of eotaxin and ECP was abolished by the glucocorticosteroid treatment. We conclude that mucosal exudation of plasma, as a global sign of active inflammatory processes, is a glucocorticosteroid-sensitive facet of allergic rhinitis in children. Exudative hyperresponsiveness, potentially caused by several weeks of mucosal inflammation, emerges as a significant feature of allergic rhinitis in children, and its development is prevented by local treatment with a glucocorticosteroid drug. The seasonal increase in ECP and the trend for an increase in eotaxin were absent in the glucocorticosteroid-treated subjects.

Hypertonic saline increases secretory and exudative responsiveness of human nasal airway in vivo.

Hypertonic saline (HS) is used in sputum induction studies. However, little is known about the physiological effects of HS on human airways in vivo. The present study takes advantage of the fact that the airway effects of topical challenges may be accurately examined in the readily accessible nasal airway. The present study specifically examines whether exposure to HS affects histamine challenge-induced exudation of plasma (alpha2-macroglobulin) and methacholine-induced secretion of mucin (fucose). Isotonic saline and HS (27 and 45 g x L(-1)), with and without concomitant histamine challenges, and with and without preceding methacholine challenges, were administered onto the nasal mucosa in 16 healthy subjects. Lavage fluid levels of alpha2-macroglobulin and fucose were analysed. Histamine produced a significant mucosal output of plasma (alpha2-macroglobulin). HS itself did not evoke exudation of alpha2-macroglobulin, but it significantly increased the plasma exudation effect of histamine. Methacholine produced a significant nasal mucosal output of fucose. HS also increased the mucin secretion (fucose), and it enhanced the secretory effect of methacholine. The authors concluded that hypertonic saline alone evokes mucinous secretion in human nasal airways in vivo and that it also enhances the exudative and secretory effects of histamine and methacholine, respectively. Through different mechanisms the HS exposure may also improve the recovery of soluble indices in human nasal airways. Whether or not the present findings are translatable to human bronchial airways remains to be examined.

Acute phase response in acute pancreatitis: a comparison with abdominal sepsis

Background: Increased knowledge on the underlying pathophysiological mechanisms in acute pancreatitis (AP) and abdominal sepsis (AS) is essential, not least for the development of novel ways of treatment. The present study aims at determining dynamic changes in the systemic inflammatory response in AP and AS. Methods: AP was induced by the intraductal injection of sodium taurodeoxycholate in the rat, while AS was induced by caecal ligation and puncture. The animals were killed 1, 3, 6 and 9 h after challenge. Plasma exudation of radiolabelled albumin, myeloperoxidase (MPO), TNF‐α, MCP‐1, superoxide and hydrogen peroxide was measured. Results: Leakage index of human serum albumin showed a significant increase early (1 h) after induction of AP and later (9 h) in AS compared to controls (P < 0.05). Hydrogen peroxide generation by circulating monocytes/macrophages was high early (1 h) in AP and after 3 and 6 h in AS. Superoxide generation increased by time after both challenges. MPO activity increased significantly, starting at 3 h in both AP and AS (P < 0.05). TNF‐α increased significantly at 6 and 9 h in both models. Conclusion: Our results indicate differences in the release of systemic inflammatory mediators and cellular response in AP and AS. However, potential similarities in end‐effect, such as the development of remote organ injury (lungs), may exist as implied by the MPO results. Further investigations of the mechanisms are crucial.

Histopathological findings in rabbits after experimental acute exposure to the Loxosceles intermedia (brown spider) venom.

Loxoscelism, the term used to describe envenomation with brown spiders, is characterized by a dermonecrotic lesion at the bite site. In the present investigation we submitted albino rabbits to an acute experimental envenomation protocol using Loxosceles intermedia (brown spider) venom, with in order to determine the pathogenesic features of the lesion induced by this spider, which is the cause of several accidents throughout the world. Rabbits received intradermal injections of the venom and were monitored over the first 4 h, and then at 12 h and 1, 2 and 5 days after envenomation. Histological specimens from 3 rabbits per time point were collected from euthanized animals and processed for histological examination by light microscopy. Major findings observed during the first 4 h were oedema, haemorrhage, degeneration of blood vessel walls, plasma exudation, thrombosis, neutrophil accumulation in and around blood vessels with an intensive diapedesis, a diffuse collection of inflammatory cells (polymorphonuclear leucocytes) in the dermis, and subcutaneous muscular oedema. Over the following hours and up to 5 days after envenomation the changes progressed to massive neutrophil infiltration (with no other leucocytes) into the dermis and even into subcutaneous muscle tissue, destruction of blood vessels, thrombosis, haemorrhage, myonecrosis, and coagulative necrosis on the 5th day.

Nitric oxide induces gelatinase A (matrix metalloproteinase 2) during rat embryo implantation

Objective To evaluate a reciprocal signaling interaction initiated by embryo-derived nitric oxide (NO) to facilitate implantation by increased production of gelatinase A (matrix metalloproteinase 2, MMP2) in uterine stroma. Design Experimental animal studies. Setting Reproductive-physiology research laboratory. Animal(s) Female syngeneic Wistar rats aged 14 weeks. Intervention(s) Vaginal smears to confirm pregnancy. Oviductal ligature to avoid the descent of blastocysts to the uterine lumen. Plasma exudation assays to locate uterine blastocyst implantation sites. Organ cultures treated with NO donors and nitric oxide synthase (NOS) inhibitors. Main outcome measure(s) Expression of MMP2 and NO was assessed by Western blot and zymography of tissue extracts and by immunofluorescence of tissue sections. Result(s) An increase in MMP2 activity was found in uterine extracts in early pregnant rats and was concentrated at implantation sites. Immunolocalization experiments showed that inducible NOS was expressed on the surface of the implanting blastocyst adjacent to the uterine epithelium at the sites of increased MMP2 expression. In organ culture experiments, NO donors were found to increase, whereas NOS inhibitors were found to decrease MMP2 activity in uterine tissue sections. Conclusion(s) Blastocyst-derived NO contributes to the production of uterine-derived MMP2, an essential component of implantation and initiation of placentation.

Critical Roles for Bradykinin and Prostanoids in Acute Inflammatory Reactions: A Search Using Experimental Animal Models

Searches for chemical mediators of inflammation underlying classical signs of inflammation i.e. heat, redness, swelling, and pain have been performed and various experimental models for evaluation of new agents to manage these inflammatory signs have been developed extensively during the last century. Now, at the beginning of the 21st-century, after great progress in gene technology, the necessity of in vivo animal study is being reconsidered. Therefore, this review introduces and describes findings obtained by the use of various experimental animal models. We have compared the inflammatory characteristics among species using reported animal models such as dye exudation in the skin, paw edema, pleurisy, and writhing reaction; then we have precisely examined mediators involved in these inflammatory reactions. In the process of plasma exudation and pain perception in the earlier phases of acute inflammation, involvement of the kallikrein-kinin system and prostanoids was demonstrated. Precisely, bradykinin, and PGI(2) among the prostanoids, are major mediators for exudation and pain perception of the initial acute phase of inflammation; both mediators collaborate to enhance these effects. PGE(2), perhaps produced by cyclooxygenase-2, was involved in induction of plasma exudation and pain perception in a later phase than the timing of involvement of PGI(2). Precise roles of various prostanoids will hopefully be clarified by the research projects in progress.

Role of mast cells in the development of pancreatitis-induced multiple organ dysfunction

AbstractBackgroundActivated mast cells can produce and release a number of inflammatory mediators involved in the pathophysiology of acute conditions. The aim of the present study was to evaluate the role of activated tissue mast cells in the pathogenesis of multiple organ dysfunction syndrome following acute pancreatitis (AP).MethodsAP was induced by the intraductal infusion of 5 per cent sodium taurodeoxycholate in the rat. Some 30 min before induction of AP, a mast cell stabilizer (sodium cromoglycate (SCG)) or antihistamines (pyrilamine, cyproheptadine, meclizine and amitriptyline) were administered intra peritoneally. Plasma exudation of radiolabelled albumin, histamine, myeloperoxidase (MPO), monocyte chemoattractant protein (MCP) 1 and adhesion molecules (platelet endothelial cell adhesion molecule (PECAM) 1 and L-selectin) were measured.ResultsThe mast cell stabilizer significantly reduced plasma exudation in the pancreas, colon and lungs (P &amp;lt; 0·05), decreased the release of histamine at 1 h (P &amp;lt; 0·05), and reduced MPO activity and MCP-1 levels in the colon and lungs (P &amp;lt; 0·05) but not in the pancreas. Expression of PECAM-1 and L-selectin on total circulating leucocytes in rats with AP and SCG pretreatment did not differ from that in sham controls, while levels in animals that had AP and saline pretreatment were half of those seen following sham operation.ConclusionActivation of mast cells after induction of AP is involved in the development of endothelial barrier dysfunction in both the pancreas and extrapancreatic organs/tissues, particularly in the lungs and colon. This may, at least partly, contribute to the sequential development of multiple organ dysfunction and organ/tissue-specific endothelial barrier dysfunction.

Nitric oxide attenuates platelet-activating factor induced nasal airway plasma extravasation in healthy subjects.

Paranasal sinuses and the nose are important sources of nitric oxide (NO) in humans but the relevance of NO production to the control of nasal airway plasma exudation and its response to inflammatory mediators such as platelet-activating factor (PAF) in healthy subjects is not well known. In this study we aimed to evaluate the effect of the nitric oxide synthase (NOS) inhibitor NG L-arginine methyl ester (L-NAME) on nasal airway plasma extravasation at baseline and after an acute challenge with PAF that induces most symptoms of rhinitis. Eleven healthy subjects were enrolled in the study. Plasma extravasation in the nasal airway was assessed by measuring the albumin content of nasal lavage. PAF challenge caused a significant increase in concentrations of albumin in the nasal lavage fluid (from 0.59 +/- 0.13 mg dL(-1) to 2.46 +/- 0.45 mg dL(-1)) after placebo. Pretreatment with L-NAME significantly prevented the increase of albumin in the nasal lavage fluid induced by PAF as compared to placebo (from 0.53 +/- 0.11 mg dL(-1) to 1.70 +/- 0.28 mg dL(-1); P < 0.005). Topical administration of a NO inhibitor is able to attenuate the nasal airway plasma extravasation induced by PAF, suggesting that NO release in vivo is involved in the nasal response to PAF.

Desloratadine reduces allergen challenge-induced mucinous secretion and plasma exudation in allergic rhinitis

Rhinorrhea is a key symptom of allergic rhinitis and this disease feature is reduced by antihistamine treatment. The nasal output of fluid in allergic rhinitis is associated with luminal appearance of bioactive molecules emanating from the microcirculation as well as the secretory apparatus. In the present study, we examined the effects of antihistamine treatment on nasal symptoms and output of mucinous secretions and plasma. Desloratadine (5 mg) was administered orally once daily for 5 days in a placebo-controlled, crossover design to 24 patients with allergic rhinitis. Nasal challenges with diluent and allergen (100 to 10,000 SQ-U) were carried out on day 5 of the treatment. The nasal mucosa was lavaged with saline, and symptoms were scored 10 minutes after each allergen challenge and 1 to 4 hours after the challenge series. Nasal lavage fluid levels of fucose and alpha2-macroglobulin were determined as indices of mucinous secretion and plasma exudation, respectively. The allergen challenges produced nasal symptoms, including rhinorrhea, and increased nasal output of fucose and alpha2-macroglobulin. Desloratadine reduced the nasal symptoms (P < 0.05 to 0.001) and output of fucose (P < 0.05 at 100 and 1,000 SQ-U) and alpha2-macroglobulin (P < 0.05 at 1,000 SQ-U). In both treatment groups, symptoms and nasal lavage fluid levels of fucose and alpha2-macroglobulin returned toward prechallenge levels 1 to 4 hours after the allergen challenge series. We conclude that the antihistamine desloratadine, in addition to a symptom-reducing effect, also reduces acute allergen challenge-induced mucinous secretion and plasma exudation in allergic rhinitis.

Utilization of a radioimmunoassay to detect the generation of Arg-Pro-Pro-Gly-Phe, a stable endproduct of bradykinin metabolism (from cultured rat aortic smooth muscle cells exposed to bradykinin)

The peptide hormone bradykinin is a mediator in many physiological and pathological processes. The generation and, to a limited extent, metabolism occur at the sites of action. The short half-life of bradykinin (∼15 s) renders measurements of its concentration in bodily fluids difficult. As a result, recent methods utilizing either ELISA or HPLC/mass spectrometry, have been developed for the measurement of the stable metabolic endproduct of bradykinin, i.e., the pentapeptide Arg-Pro-Pro-Gly-Phe (RPPGF; BK[1–5]). Both have been successfully used to quantitate levels of RPPGF in plasma, pulmonary and nasal exudates. In this study, we demonstrate the characterization and utility of a radioimmunoassay for the measurement of RPPGF, using a newly synthesized radioiodinated analogue of RPPGF, i.e., RPPG( 125I)F. This radioimmunoassay shows an IC 50 of 80.5±7.4 pg/tube ( n=23) with a linear range of detection between 10 and 500 pg/tube. The assay was used to demonstrate the time-dependent generation of RPPGF by cultured rat aortic vascular smooth muscle cells exposed to bradykinin (100 ng/ml). Peak generation of RPPGF was 74.5±9.7 pmol/well ( n=5) after 24 h of incubation. Captopril, an inhibitor of angiotensin-converting enzyme (kininase II), inhibited generation in a concentration-dependent manner. The results characterize a new radioimmunoassay for the stable metabolic endproduct of bradykinin, RPPGF.

BacillusSpecies Are Present in Chewing Tobacco Sold in the United States and Evoke Plasma Exudation from the Oral Mucosa

Five Bacillus species, predominantly Bacillus megaterium and Bacillus pumilus, were isolated from two popular brands of commercially available chewing tobacco [(5.0 +/- 1) x 10(6) CFU/ml of supernatant; results for four experiments]. Moreover, the supernatant of the Bacillus culture evoked plasma exudation from postcapillary venules in the intact hamster cheek pouch, exudation that was mediated by the kallikrein/kinin metabolic pathway. Taken together, these data indicate that Bacillus species contaminate chewing tobacco commercially available in the United States and elaborate a potent exogenous virulence factor(s) that injures the oral mucosa.

Systemic Capillary Leak Syndrome, Leukotrienes, and Anaphylaxis

The association of cysteinyl leukotrienes with plasma exudation allowed the authors to form the hypothesis that rates of leukotriene excretion would be increased in the acute phase of systemic capillary leak syndrome (SCLS) and that leukotriene-modifier therapy would reduce the frequency and severity of life-threatening episodes. The authors report the association of SCLS in 3 cases, 1 with seafood-induced anaphylaxis. Rates of urinary leukotriene excretion were greater during the evolution of an episode than after resolution. In a third case, the rate of urinary leukotriene excretion was significantly higher when symptoms were evolving than when they were absent (230 ± 17 vs 110 ± 6 pg/mg, P &lt; 0.001). Treatment with a leukotriene receptor (cys-LT1) antagonist eliminated episodes in 1 patient. Treatment with the 5-lipoxygenase inhibitor zileuton was completely effective in another patient and prevented life-threatening episodes in the patient with SCLS after seafood exposure. The authors' finding that allergen exposure—associated episodes of SCLS were eliminated by allergen avoidance implies that anaphylaxis can present as SCLS. The acute phase of all 3 forms of SCLS (paraprotein associated, anaphylaxis associated, and idiopathic) is associated with increased excretion of cystinyl leukotrienes, and leukotriene-modifier treatment appears to control the disease.

The role of ATP-sensitive potassium channels in neutrophil migration and plasma exudation.

Neutrophil activation and migration during an inflammatory response is preceded or accompanied by plasma membrane electrical changes. Besides changes in calcium currents, neutrophils have a high permeability to potassium, mainly through potassium channels. However, the significance of potassium channels in neutrophil physiology is still unclear. Here, we show that the treatment of rats with the ATP-sensitive potassium channel blocker glibenclamide (4, 20, or 40 micromol/kg) dose dependently decreased carrageenan-, N-formyl-methionyl-leucyl-phenylalanine (fMLP)-, and lipopolysaccharide-induced neutrophil influx and fluid leakage into the interpleural space. On the other hand, minoxidil (an ATP-sensitive potassium channel opener; 25, 50, and 100 micromol/kg) increased both neutrophil influx and fluid leakage induced by a submaximal dose of carrageenan. In addition, in vitro human neutrophil chemotaxis induced by leukotriene B4 or fMLP (both 1 microM) was fully blocked by glibenclamide (10, 30, and 100 microM) or tetraethylammonium (a nonselective potassium channel blocker; 1, 3, and 10 mM). Thus, our results disclose the possibility that ATP-sensitive potassium channels may have a role in neutrophil migration and chemotaxis and plasma exudation in the inflammatory response.

Morphological and biochemical evidence of blood vessel damage and fibrinogenolysis triggered by brown spider venom.

The venom of the brown spider is remarkable because it causes dermonecrotic injury, hemorrhagic problems, hemolysis, platelet aggregation and renal failure. The mechanism by which the venom causes hemorrhagic disorders is poorly understood. Rabbits intradermally exposed to the venom showed a local hemorrhage starting 1 h after inoculation and reaching maximum activity between 2 and 3 days. Biopsies examined by light and transmission electron microscopy showed subendothelial blebs, vacuoles and endothelial cell membrane degeneration in blood vessels, plasma exudation into connective tissue, and fibrin and thrombus formation within blood vessels. Loxosceles intermedia venom incubated with fibrinogen partially degrades Aalpha and Bbeta chains of intact fibrinogen, and significantly cleaves all Aalpha, Bbeta and gamma chains when they were separated or when fibrinogen is denatured by boiling. Proteolytic kinetic studies showed that the Aalpha chain is more susceptible to venom hydrolysis than the Bbeta chain. The fibrinogenolysis is blocked by ethylenediamine tetraacetic acid and 1,10-phenanthroline, but not by other protease inhibitors. Human plasma incubated with the venom had coagulation parameters such as prothrombin time, activated partial thromboplastin time and thrombin time increased. Through molecular sieve chromatography, we isolated a venom toxin of 30 kDa with fibrinogenolytic activity. We propose that the local and systemic hemorrhagic disorders evoked in loxoscelism are consequences of direct venom fibrinogenolysis together with cytotoxicity to subendothelial structures and endothelial cells in blood vessels.

Acute Exudative Inflammation and Nasally Exhaled Nitric Oxide Are Two Independent Phenomena

Background: Increased levels of nitric oxide (NO) and the exudations of plasma proteins to the airway lumen have both been considered characteristics of airway inflammation. The aim of the present study was to investigate a possible relationship between nasal NO concentrations and acutely induced exudative inflammation of the nasal mucosa. Methods: Twelve healthy non-allergic subjects participated. Nasal challenges with saline, histamine 40 µg/ml (H1), histamine 400 µg/ml (H2), oxymethazoline, 0.25 mg/ml (OXY), and a combination of oxymethazoline 0.25 mg/ml and histamine 800 µg/ml (OXYH), were performed on separate occasions. Exhaled NO was measured after each challenge, and α₂-macroglobulin (as a marker of plasma exudation) was measured in nasal lavage fluids after the H1 and H2 challenges. Results: The mean baseline NO in all measurements was 164 ± 10.3 ppb. Saline and H1 challenge did not change NO and α₂-macroglobulin levels. H2 challenge showed a tendency to reduce NO levels, and the most pronounced decrease was seen after 10 min (–36.3 ± 16.3%, p = 0.07). This reduction was sustained throughout the registration period. Simultanousley with the decrease in NO, α₂-macroglobulin levels were increased significantly. OXY challenge alone reduced NO significantly throughout the whole registration period. Maximum decrease was seen at 40 min (–21.3 ± 3.4%, p = 0.03). The OXYH challenge also reduced NO, with a maximal reduction recorded at 10 min (–29.4 ± 6.4%, p = 0.03). The reduction of NO was sustained throughout the registration period (p < 0.01). Conclusion: Histamine 400 µg/ml induced a prompt plasma exudation response whereas a decrease in nasal NO was registered, suggesting that these two events are not necessarily linked. Furthermore it was shown that the vasoconstrictor oxymethazoline reduced nasal NO, which could be related to reduced mucosal blood flow, whereas the reduction of nasal NO after histamine challenge remains to be elucidated.

Role of mast cells in the development of pancreatitis-induced multiple organ dysfunction.

Activated mast cells can produce and release a number of inflammatory mediators involved in the pathophysiology of acute conditions. The aim of the present study was to evaluate the role of activated tissue mast cells in the pathogenesis of multiple organ dysfunction syndrome following acute pancreatitis (AP). AP was induced by the intraductal infusion of 5 per cent sodium taurodeoxycholate in the rat. Some 30 min before induction of AP, a mast cell stabilizer (sodium cromoglycate (SCG)) or antihistamines (pyrilamine, cyproheptadine, meclizine and amitriptyline) were administered intra peritoneally. Plasma exudation of radiolabelled albumin, histamine, myeloperoxidase (MPO), monocyte chemoattractant protein (MCP) 1 and adhesion molecules (platelet endothelial cell adhesion molecule (PECAM) 1 and L-selectin) were measured. The mast cell stabilizer significantly reduced plasma exudation in the pancreas, colon and lungs (P < 0.05), decreased the release of histamine at 1 h (P < 0.05), and reduced MPO activity and MCP-1 levels in the colon and lungs (P < 0.05) but not in the pancreas. Expression of PECAM-1 and L-selectin on total circulating leucocytes in rats with AP and SCG pretreatment did not differ from that in sham controls, while levels in animals that had AP and saline pretreatment were half of those seen following sham operation. Activation of mast cells after induction of AP is involved in the development of endothelial barrier dysfunction in both the pancreas and extrapancreatic organs/tissues, particularly in the lungs and colon. This may, at least partly, contribute to the sequential development of multiple organ dysfunction and organ/tissue-specific endothelial barrier dysfunction.

The effects of heparin and related molecules on vascular permeability and neutrophil accumulation in rabbit skin.

Unfractionated heparin (UH) has been shown to possess a wide range of properties which are potentially anti-inflammatory. Many of these studies, including effects of heparin on adhesion of inflammatory cells to endothelium, have been carried out in vitro. In the present study, we have used radioisotopic techniques to study the effect of UH, and related molecules, on in vivo inflammatory responses (plasma exudation (PE) and PMN accumulation) in rabbit skin induced by cationic proteins, mediators and antigen. Intradermal (i.d.) pretreatment with UH dose-dependently inhibited poly-L-lysine (PLL)-induced responses. The same treatment had no effect on antigen (extract of Alternaria tenuis, AT)-, formyl-methionyl-leucyl-phenylalanine (fMLP)- or leukotriene (LT) B(4)-induced responses, although i.d. dextran sulphate (DS) significantly inhibited responses to all of these mediators. High dose (10,000 u kg(-1)) intravenous UH significantly decreased cutaneous responses to fMLP and LTB(4). By comparison, the selectin inhibitor, fucoidin, and DS, were very effective inhibitors of these responses, and of responses to AT and PLL. In contrast to the weak effect in the in vivo studies, UH significantly inhibited in vitro homotypic aggregation of rabbit PMNs, showing that it can modify PMN function. Our data with i.d. UH confirm the important ability of this molecule to interact with and neutralize polycationic peptides in vivo, suggesting that this is a prime role of endogenous heparin. The lack of effect of exogenous heparin on acute inflammatory responses induced by allergen, suggests that cationic proteins are unlikely to be primary mediators of the allergen-induced PE or PMN accumulation.