Roles of leukotrienes in two rat allergic inflammatory models; IgE-mediated and IgG-antigen complex-induced pleurisies

Rat IgE pleurisy was induced by the injection of di-nitrophenol-conjugated bovine serum albumin (DNP-BSA) 48 hours after the intrapleural injection of rat anti-DNP-IgE serum. IgG-BSA complex pleurisy was also induced by the intrapleural injection of IgG-BSA complexes produced at the optimum ratio in vitro. Plasma exudation was markedly increased in the first 20 minutes, but not observed thereafter, in IgE pleurisy, whereas marked plasma exudation in the first 20 minutes was followed by weak exudation at three and five hours in IgG-BSA complex pleurisy. Leukotrienes (LTs) E4 (100 ng/rat), D4 (32) and B4 (16) were detected on HPLC in the pleural exudate in the first 20 minutes of IgG-BSA complex pleurisy, but less (9 ng/rat) LTE4 alone was detected in the five-hour exudate. The first 20-minute pleural exudate contained 13 ng/rat of LTE4 in IgE pleurisy. The plasma was completely inhibited by simultaneous treatment of rats with pyrilamine (2.5 mg/kg, i.p.) and methysergide (3 mg/kg, i.p.), as it was in compound 48/80-induced pleurisy. In IgG-BSA complex pleurisy, 90% of the pleural exudate for the first 20 minutes was inhibited by the same treatment, and the rest was completely suppressed by simultaneous treatment with an intrapleural injection of AA-1777, a selective 5-lipoxygenase inhibitor. AA-1777 alone did not reduce the plasma exudation significantly. The 5-lipoxygenase inhibitor was also very effective in reducing the migrating numbers of polymorphonuclear and mononuclear leukocytes to half, without affecting the eosinophils of mast cells.     

The role of kinin B1 in the plasma extravasation of carrageenin-induced pleurisy

The role of des-Arg9-bradykinin (des-Arg9-BK) and kinin B1 receptor in the plasma extravasation of rat carrageenin-induced pleurisy was investigated employing B1 receptor agonist and antagonists and kininogen-deficient rats. Expression of the B1 receptor mRNA in pleura was induced from 3 to 5 h after the injection of carrageenin into the pleural cavity of Sprague-Dawley rats. Exogenous injection of des-Arg9-BK into the pleural cavity provoked a significant increase in plasma extravasation in 5 h carrageenin-induced pleurisy, but not in 20 min kaolin-induced pleurisy. The level of immunoreactive des-Arg9-BK in the exudate of 5 h carrageenin-induced pleurisy was higher than that of bradykinin (BK). Administration of the B1 receptor antagonists, des-Arg9-[Leu8]-BK or des-Arg9-D-Arg-[Hyp3, Thi5, D-Tic7,Oic8]-BK significantly reduced the exudation rate. However, intrapleural administration of des-Arg9-BK to plasma kininogen-deficient. Brown Norway-Katholiek rats did not result in a further increase in the plasma extravasation. In conclusion, endogenously generated des-Arg9-BK could contribute to the plasma extravasation in carrageenin-induced pleurisy via mediation of the inducible B1 receptor.     

Pharmacological profile of AA-861, A 5-lipoxygenase inhibitor

AA-861, a selective 5-lipoxygenase inhibitor, suppressed A23187-induced formations of 5-HETE and LTB₄ in rat peritoneal macrophages. Immunologically-stimulated generation of SRS-A was also inhibited in guinea pig lung and rat peritoneal cavity. AA-861 had no effects on histamine release from rat mast cels or passive cutaneous anaphylaxis in rats. Essentially no antagonistic activity to LDT₄ or histamine was observed. This compound exerted an obvious inhibition of allergic bronchoconstriction in guinea pigs and a moderate reduction of carrageenin-induced paw edema and pleurisy in rats. These findins suggest that SRS-A plays an important role in asthmatic and inflammatory reactions.     

The anti-inflammatory mechanism of MK-447 in rat carrageenin-induced pleurisy

Intrapleural injection of 2% λ-carrageenin caused the accumulation of exudate up to 19 hr. The rate of plasma exudation, measured by the exuded dye amounts for 20 min in the pleural cavity after intravenous injection of pontamine sky blue, showed a peak at 5 hr. Aspirin (100 mg/kg, i. p.) suppressed the dye exudation up to 5 hr, but did not at 7 hr. This inhibition coincided with the decrease of the PG and TXB₂ levels, which were measured by gas chromatography-mass spectrometry, in the pleural exudate. In _vitro experiments, MK-447, a phenolic compound, stimulates PG endoperoxide biosynthesis at lower doses and inhibits it at higher doses, acting as a tryptophan-like cofactor required by PG endoperoxide synthetase. This drug (0.3, 1.0 and 3.0 mg/kg, i. p.) suppressed the dye exudation dose-dependently up to 5 hr, but did not at 7 hr even at a higher dose, in combination with the dose-dependent decrease of the pleural level of PGE₂, which was reported to be a major PG among PGs and TXB₂ in the exudate in inducing the plasma exudation (Harada ; Prostaglandins, : 881, 1982). Thus, the anti-inflammatory action of MK-447 can be explained by inhibition of PGE₂ generation, giving no consideration to the role of oxygen-derived free radicals as a prime mediator in inflammation.     

Difference in the in vitro metabolism of leukotrienes in the exudates from allergic and nonallergic rat pleurisies

The metabolism of leukotrienes (LTs) in the cell-containing inflammatory exudate of rat pleurisy was studied in vitro. The exudates of both nonallergic carrageenin-induced pleurisy and IgG immune complex-mediated pleurisy converted 3H-LTB4 to 20-OH LTB4, but virtually did not metabolized 3H-LTC4 or 3H-LTE4 up to 2 hrs. 3H-LTD4 was changed to LTC4 by the exudate of non-allergic pleurisy, whereas 3H-LTD4 was metabolized to LTE4 by that of allergic pleurisy. Reflecting on the different metabolism, the gamma-glutamyl transpeptidase activity in the exudate of carrageenin-induced pleurisy was significantly higher than that in IgG immune complex mediated pleurisy. The enzyme activity was not derived from the blood itself, but from the infiltrated polymorphonuclear leukocytes. The activity of the cell homogenate in both exudates was not significantly different. Thus, it could be concluded that the difference in the metabolism of LTD4 between the nonallergic and allergic pleural exudates in vitro was mainly attributable to the enhanced activity of the gamma-glutamyl transpeptidase released in the exudate.     

Role of prostaglandin H synthase-2 in prostaglandin E2 formation in rat carrageenin-induced pleurisy

Rat carrageenin-induced pleurisy was used to clarify the role of prostaglandin H synthase (PGHS)-2 in acute inflammation. Intrapleural injection of 0.2 ml of 2% λ-carrageenin induced accumulation of exudate and infiltration of leukocytes into the pleural cavity. When PGHS-1 and -2 proteins in the pleural exudate cells were analyzed by Western blot analysis, PGHS-2 was detectable from 1 hr after carrageenin injection. Its level rose sharply, remained high from 3 to 7 hr after injection, and then fell to near the detection limit. PGHS-1 was also detected, but kept almost the same level throughout the course of the pleurisy. Levels of prostaglandin (PG) E₂ and thromboxane (TX) B₂ in the exudate increased from hour 3 to hour 7, and then declined. Thus, the changes of the level of PGE₂ were closely paralleled those of PGHS-2.The selective PGHS-2 inhibitors NS-398, nimesulide and SC-58125 suppressed the inflammatory reaction and caused a marked decrease in the level of PGE₂ but not in those of TXB₂ and 6-keto-PGF_1α. These results suggest that the PGHS-2 expressed in the pleural exudate cells may be involved in PGE₂ formation at the site of inflammation.     

胸腔注射糖皮质激素联合标准四联抗结疗法对结核性胸膜炎患者临床症状及肺功能的影响

摘要 目的：探讨胸腔注射糖皮质激素联合标准四联抗结疗法对结核性胸膜炎患者肺功能及临床症状的影响。方法：选取2013年1月到2020年5月期间来我院进行诊治的结核性胸膜炎患者756例，入选的患者按照随机数字表法分为对照组和实验组，各378例。对照组予以标准四联抗结疗法治疗，实验组予以胸腔注射糖皮质激素联合标准四联抗结疗法治疗。对比两组疗效、肺功能[第1s用力呼气容积占预计值百分比（FEV₁%pred）、每分钟最大通气量占预计值百分比（MVV%pred）、用力肺活量占预计值百分比（FVC%pred）]，记录两组胸水吸收时间、胸膜厚度、临床症状缓解时间、住院时间、并发症及胸膜肥厚粘连发生情况。结果：实验组的临床总有效率较对照组高（P<0.05）。治疗后，两组FEV₁%pred、MVV%pred、FVC%pred均升高，且实验组高于对照组（P<0.05）。实验组临床症状缓解时间、胸水吸收时间、住院时间较对照组短（P<0.05），胸膜厚度大于对照组（P<0.05）。实验组的胸膜肥厚粘连、并发症总发生率低于对照组（P<0.05）。结论：胸腔注射糖皮质激素联合标准四联抗结疗法治疗结核性胸膜炎，疗效可靠，可改善患者肺功能，促进症状改善。     

Expression and function of cyclooxygenase-2 in mesothelial cells during late phase of rat carrageenin-induced pleurisy.

We have previously shown that the inducible isoform of the cyclooxygenases, COX-2, is strongly expressed in pleural exudate leukocytes early (between 3 and 7 hr after irritation) during rat carrageenin-induced pleurisy. The present study further examined COX-2 expression and disclosed that mesothelial cells expressed COX-2 later (12 to 24 hr after irritation) in this model. A COX-2 inhibitor, nimesulide, lowered the intrapleural level of 6-keto-PGF1alpha and inhibited hyperplasia of the pleural matrix, suggesting that COX-2 expressed in mesothelial cells may play a role in the synthesis of extracellular matrix through formation of PGI2.     

Cyclooxygenase-2-derived prostaglandin E2 and lipoxin A4 accelerate resolution of allergic edema in Angiostrongylus costaricensis-infected rats: relationship with concurrent eosinophilia

In noninfected rats, challenge with allergen following local IgE sensitization induced a pleurisy marked by intense protein exudation that plateaued from 30 min to 4 h after challenge, reducing thereafter. Infection of rats with Angiostrongylus costaricensis induced a 5-fold increase in blood eosinophil numbers by 25 days postinfection, whereas the numbers of eosinophils in the pleural cavity ranged from normal to a weak increase. In infected rats, identically sensitized, challenge with Ag induced a much shorter duration of pleural edema with complete resolution by 4 h, but no change in the early edema response. In parallel, infection increased the number of eosinophils recovered from the pleural cavity at 4 h, but not at 30 min, following allergen challenge. Pretreatment with IL-5 (100 IU/kg, i.v.) also increased eosinophil numbers in blood and, after allergen challenge, shortened the duration of the pleural edema and increased pleural eosinophil numbers. There were increases in the levels of both PGE2 and lipoxin A4 (LXA4) in pleural exudate. Selective cyclooxygenase (COX)-2 inhibitors, NS-398, meloxicam, and SC-236, did not alter pleural eosinophilia, but reversed the curtailment of the edema in either infected or IL-5-pretreated rats. Pretreatment of noninfected animals with the PGE analogue, misoprostol, or two stable LXA4 analogues did not alter the magnitude of pleural exudation response, but clearly shortened its duration. These results indicate that the early resolution of allergic pleural edema observed during A. costaricensis infection coincided with a selective local eosinophilia and seemed to be mediated by COX-2-derived PGE2 and LXA4.     

The modulatory role played by TNF-alpha and IL-1 beta in the inflammatory responses induced by carrageenan in the mouse model of pleurisy

We describe here the modulation caused by intrapleural (i.pl.) injection of the cytokines TNF-alpha and IL-1beta and their specific antibodies in the early (4 h) and late (48 h) inflammatory responses caused by injection of carrageenan (Cg) into the mouse pleural cavity. The antibodies against TNF-alpha and IL-1beta, when injected 30 min prior to Cg, reduced, in a graded and significant manner, both exudation and cell migration in the early (4 h) phase, while they potentiated or had no effect in the late (48 h) phase of Cg response. The natural IL-1 receptor antagonist IL-1RA, given 30 min prior to Cg, reduced the exudation by about 50% and abolished the total and differential cell migration in the early (4 h) and late (48 h) phases of the Cg responses. The i.pl. injection of TNF-alpha or IL-1beta, 5 min prior to Cg, caused graded increase in the exudation of the early (4 h) and late (48 h) phases of the Cg-induced inflammatory responses. In contrast, these treatments markedly reduced the total and differential cell migration at 4 h, while having little or no effect on the late (48 h) phase of the Cg pleurisy. These findings extend previous results and demonstrate that the pro-inflammatory cytokines TNF-alpha and IL-1beta have a critical role in controlling both cell migration and exudation caused by injection of Cg in the mouse pleural cavity. Together, these findings may be relevant to the understanding of the mechanisms involved in airway inflammatory responses.     

Changes in the levels of prostaglandins and thromboxane and their roles in the accumulation of exudate in rat carrageenin-induced pleurisy — a profile analysis using gas chromatography-mass spectrometry —

Injection of γ-carrageenin into t he pleural cavity of rats caused the accumulation of the pleural exudate. When levels of prostaglandins (PGs) and thromboxane (TX) B₂ were quantified by gas chromatography-mass spectrometry as their methyl ester (ME)-dimethyllisopropylsilyl (DMiPS) ether or ME-methoxine-DMiPS ether derivatives, 6-keto-PGF_1α reached the maximum at 1 hr after carrageenin, then PGE₂ and TXB₂ showed peaks at 3 hr and waned off before 9 hr. he PGF_2α level was kept low, but PGD₂, PGE₁ and PGF_1α were not detected. Aspirin (100 mg/kg, i.p.) significantly decreased the PG and TXB₂ levels and suppressed the rate of plasma exudation until 5 hr, but did not at 7 hr, when it was measured by the amount of exuded pontamine sky blue injected intravenously. OKY-025 (300 mg/kg, i.p.), a selective TXA synthetase inhibitor, and tranylcypromine (20 mg/kg, i.p.), a PGI synthetase inhibitor, could not extensively inhibit the accumulation of the exudate. These results suggest that the cyclooxygenase products of arachidonic acid, particularly PGE₂, definitely play an important role in the exudation during the first 5 hr.     

The effects of IL-6 and IL-10 and their specific antibodies in the acute inflammatory responses induced by carrageenan in the mouse model of pleurisy

This study evaluates the effects of intrapleural (i.pl.) injection of interleukin (IL-6) and IL-10 and their specific antibodies on the early (4 h) and late (48 h) inflammatory responses caused by carrageenan (Cg) injected into the mouse pleural cavity. The i.pl. injection of IL-6, 5 min prior to Cg, reduced in a dose-dependent and significant manner, the exudation and total and differential leukocyte migration according to assessment in both the early (4 h) and the late (48 h) phases of Cg inflammatory response (P<0.01). Intrapleural injection of IL-10, 5 min prior to i.pl. injection of Cg, resulted in a significant inhibition of the early phase (4 h) (P<0.01), but had no significant effect in relation to the late (48 h) phase of Cg response. The antibodies anti-IL-6 (given i.pl. 30 min prior to Cg) caused a significant decrease in both total and differential leukocyte influx, but significantly increased exudation according to assessment 4 h after pleurisy induction by Cg (P<0.01). In contrast, anti-IL-10 antibody caused graded and marked increase of both total and differential leukocyte influx and also increased fluid leakage as assessed 4 h after Cg injection (P<0.01). In the late phase (48 h) these antibodies increased the inflammatory parameters (anti-IL-6) studied or had no effect (anti-IL-10). Taken together, the current results confirm and extend previous data from the literature by showing that IL-6 and IL-10 regulate several signs of inflammatory response, here characterized by marked inhibition of polymorphonuclear cell influx and blockage of fluid leakage to the site of Cg-induced pleurisy in the mouse.     

Effects of methotrexate upon inflammatory parameters induced by carrageenan in the mouse model of pleurisy

BACKGROUND: The model of pleurisy induced by carrageenan exhibits a biphasic response (4 and 48 h) and permits the quantification of exudate, cell migration and certain enzymes such as myeloperoxidase (MPO) and adenosine-deaminase (ADA) that are markers of activated leukocytes. AIMS: The present study evaluates whether there exists, in the pleurisy model, a significant inhibition of ADA and MPO enzymes, leukocyte kinetics and other markers of inflammation [nitric oxide (NO) levels, exudation] caused by methotrexate treatment by the intraperitoneal (i.p.) route. METHODS: The pleurisy was induced by carrageenan (1%) in mice, and the parameters were analyzed 4 and 48 h after. RESULTS: After the induction of inflammation (4 h), methotrexate (20 mg/kg, i.p., 24 h before pleurisy induction) inhibited the leukocyte infiltration (p < 0.05), NO levels and MPO activity (p < 0.01), but not ADA activity and fluid leakage (p > 0.05). Regarding the second phase of pleurisy (48 h), methotrexate (40 mg/kg, i.p., 0.5 h before pleurisy induction) inhibited the leukocyte infiltration (p < 0.05), fluid leakage, NO levels (p < 0.01), and ADA and MPO activity (p < 0.05). CONCLUSIONS: These findings support the evidence that the acute administration of methotrexate has an important systemic anti-inflammatory activity in the studied inflammatory model. This effect was due to a significant inhibition on both neutrophil and mononuclear cells, being less marked in relation to exudation 48 h after. In relation to the enzymes studied and to NO levels, the findings support the evidence that methotrexate inhibits both enzymes (MPO and ADA) from leukocytes at the site of injury, thus reflecting the activation of both neutrophils and lymphocytes, respectively. Furthermore, the inhibiting effect on NO in both phases of pleurisy induced by carrageenan (4 and 48 h) indicates that methotrexate acts on constitutive and/or inducible NO synthases by means of different cells of the pleural cavity.     

Proinflammatory role of glucocorticoid-induced TNF receptor-related gene in acute lung inflammation

Glucocorticoid-induced TNFR-related gene (GITR) participates in the immune/inflammatory response. Because GITR expression has been described in cells other than T lymphocytes, we investigated whether it also modulates acute inflammatory response. Using GITR-deficient (GITR(-/-)) mice, we analyzed the role of GITR in the development of carrageenan-induced lung inflammation (pleurisy) by studying several proinflammatory markers 2-8 h after carrageenan injection. When compared with GITR(+/+), GITR(-/-) mice exhibited decreased production of turbid exudate containing a lower number of leukocytes. This was correlated with the reduction of inflammatory markers (including TNF-alpha, IL-1beta, myeloperoxidase, inducible NO synthase, and cyclooxygenase 2) in the pleural exudate and/or in the lung. Moreover, endothelial cells expressed lower levels of adhesion molecules. In lungs of GITR(+/+) mice, GITR ligand expression was not modulated during pleurisy, while that of GITR increased, as a consequence of increased infiltration by GITR-expressing cells and of GITR up-regulation in macrophages and endothelial cells. Finally, cotreatment of GITR(+/+) mice with carrageenan and Fc-GITR fusion protein decreased the number of inflammatory cells (pleural macrophages and lung neutrophils) as compared with carrageenan treatment alone, confirming that GITR plays a role in the modulation of pleurisy.     

Urinary LTE4 Levels as a Diagnostic Marker for IgE-Mediated Asthma in Preschool Children: A Birth Cohort Study

Objectives

Leukotrienes play a central pathophysiological role in allergic asthma. The aim of this study was to investigate the utility of measuring urinary leukotriene E₄ (LTE₄) levels in the diagnosis of atopic diseases in early childhood.

Methods

Children aged 0 through 4 years from a birth cohort in the Prediction of Allergies in Taiwanese Children (PATCH) study were enrolled. Urinary LTE₄ levels were measured and its association between total serum IgE levels, allergen-specific IgE sensitization and atopic diseases were assessed.

Results

A total of 182 children were regular followed up at clinics for a four-year follow-up period. Urinary LTE₄ levels appeared to be elevated in children with total serum IgE levels exceeding 100 kU/L, allergen-specific IgE sensitization after 2 years of age. Elevation of urinary LTE₄ levels (≥500 pg/mg of creatinine) significantly discriminated high serum total IgE levels (≥100 kU/L) at age 2 (P = 0.027). A higher level of total serum IgE or urinary LTE₄ was significantly associated with the risk of developing allergic rhinitis and asthma at age 3. A significantly higher urinary LTE₄ level was found in children with a combination of IgE sensitization and asthma at age 4.

Conclusions

Urinary LTE₄ levels appear to be highly associated with IgE sensitization and its related allergic airway diseases after age 2. The measurement of urinary LTE₄ (≥500 pg/mg of creatinine) could not only be a non-invasive method for atopic predisposition but also potentially provide a strategy for the diagnosis and management of asthma in preschool children.     

The effects of a 5-lipoxygenase inhibitor, AA-861, on PGI2-like substance production in guinea-pig lungs

To determine the effects of AA-861 on PGI₂ production in guinea-pig lungs, 3 g of guinea-pig lung was chopped in 4 ml of buffer (control group), in buffer with 4 μg/ml indomethacin (indomethacin group) and in buffer with 2.5 × 10⁻⁵M AA-861 (AA-861 group). The chopped lungs were incubated for 30 min. 250 μl of incubation medium from each group was assessed before and after 3, 5, 10, 15, 20, 25 and 30 min of incubation. The incubation medium was centrifuged and the supernatant was tested for a PGI₂-like substance (PGI₂) by platelet aggregation inhibition. PGI₂ was produced mainly during the initial 3–5 min of incubation and was decreased thereafter. PGI₂ production was almost completely inhibited in the indomethacin group at all of the incubation times and was partially inhibited in the AA-861 group during the initial 3–5 minutes. Endogenous 5-lipoxygenase products generated in the early stages of incubation seem to be involved in PGI₂ production in guinea-pig lungs.     

Sequential appearance of IL-1 and IL-6 activities in rat carrageenin-induced pleurisy.

IL-1 and IL-6 activities were measured in the pleural exudate of rats during carrageenin-induced pleurisy to examine the relationship of the local production of cytokines to the inflammatory reaction. Time courses of appearance of the cytokines and inflammatory parameters in the exudate were compared. IL-1 activity and exudate volume started to increase at 1 h after the carrageenin injection, and then slightly later IL-6 activity and leukocyte number began to increase. IL-1 showed peak activity of approximately 700 U at 3 h and IL-6, of 6000 U at 5 h in the exudate, whereas exudate volume and number of polymorphonuclear leukocytes continued to increase thereafter. Furthermore, IL-6 level in the plasma of the carrageenin-injected rats showed a peak at 4 h (30 U/ml), and when rhIL-1 alpha (100,000 U) was intrapleurally injected, the more rapid increase in plasma IL-6 level was demonstrated at 1 h (30 U/ml). This latter rise was neutralized with simultaneous injection of anti-rhIL-1 alpha antibody. These facts indicate the possibility that IL-1 produced in the exudate or injected could rapidly propagate a signal to induce IL-6 production in the circulation. It took several hours to transmit an inflammatory signal that stimulated the liver to synthesize the acute-phase protein, T-kininogen. The time lag from the peak induction of IL-1 to the T-kininogen-increase in the pleurisy corresponded well to the interval for T-kininogen-increase by exogenous rhIL-1 alpha injection. These results strongly suggest that the initial inflammatory stimulus induces sequentially IL-1, IL-6, and T-kininogen production in this carrageenin inflammation.     

Eicosanoid release and early changes in two acute non specific inflammatory reactions. Major role of prostacyclin and leukotrienes.

We have compared the early development (0-4h) of two acute non-specific inflammatory reactions induced by the intrapleural injection of isologous serum or a suspension of CaPP crystals. The intensity of the reactions was assessed in terms of the exudate volume, the number and ratio of pleural cells and different cell functions and secretions. The number of exudative cells elicited by isologous serum was higher than with CaPP but the PMN/Monocytes ratio was the same. The amount of protein in the serum-induced exudate was constant from 1 h to 4 h and was similar in the CaPP-induced pleural exudate at the latter time. The amount of complement increased similarly in the two models. The chemotactic potency of the exudates and cell supernatants following incubation showed similar values in the two models. Eicosanoid levels were higher in CaPP--than in isologous serum-induced exudates. Prostacyclin and peptidoleukotrienes were released in specially large amounts at the very outset of the inflammatory reactions.     

Leukotriene E4 causes pulmonary vasoconstriction,not inhibited by meclofenamate

Leukotriene E₄ (LTE₄) appears to be a rather stable product of the lipoxygenase pathway. Its action in the pulmonary circulation is unknown. Therefore we investigated its effect on the circulation of isolated rat lungs perfused with a cell- and plasma-free solution. Synthetic LTE₄ in doses from .15 μg to 5μg/ .25 ml .9% NaCl injected as a bolus in the pulmonary artery during normoxia caused a fast, transient perfusion pressure increase within seconds. This was followed by a slow rise in baseline perfusion pressure (normoxia) over 25 min. In addition, 5 μm LTE₄ caused edematogenic lung damage. Injection of 1.5 μg LTE₄ during hypoxic vasoconstriction caused fast, transient pressure rises, similar to normoxic conditions. 6-keto-PGF_1α and TXB₂ were measured in the lung effluent before and after LTE₄ injection. Neither 6-keto-PGF_1α nor TXB₂ production changed after LTE₄ injection. Meclofenamate (.5 μg/ml) increased the fast, transient and the slow, sustained pressure rise. We conclude that LTE₄ caused direct pulmonary vasoconstriction unrelated to cycloxygenase products.     

Generation of inflammatory cytokines in zymosan-induced pleurisy in rats: TNF induces IL-6 and cytokine-induced neutrophil chemoattractant (CINC) in vivo

Levels of inflammatory cytokines tumour necrosis factor (TNF), interleukin 1 (IL-1), IL-6, and cytokine-induced neutrophil chemoattractant (CINC), which is a member of the alpha-chemokine family in rats, were measured in the pleural exudates during zymosan-induced pleurisy to examine the relationship between the local production of cytokines and the inflammatory reaction. All four cytokine levels in the pleural exudate began to increase after 1-2 h, preceding the influx of neutrophils, and peaked after 4-5 h. Thereafter, these cytokine levels declined after 24 h, whereas the exudate volume still continued to increase and leukocyte number reached a plateau. Concomitant injection of actinomycin D (10 microg) with zymosan markedly suppressed the neutrophil infiltration, parallel with CINC production in the pleural exudate at 4 h. A transient elevation of IL-6 level, peaking at 5 h, and subsequent rise in the level of an acute-phase protein, T-kininogen, were also observed in the plasma. When recombinant human TNF-alpha (rhTNF-alpha) (20 000 U) was intrapleurally injected a rapid increase in pleural CINC level, followed by neutrophil infiltration, and a sharp rise in IL-6 level in the plasma, followed by an increase in T-kininogen, were demonstrated. These results suggest that CINC produced in the pleural exudate may participate in neutrophil infiltration, that IL-6 induced in the plasma stimulates T-kininogen production, and that endogenous TNF may be partly involved in the induction of CINC and IL-6 in this zymosan inflammation.