Inhibition by dexamethasone of histamine production in allergic inflammation in rats

In an allergic inflammation model of air pouch type in rats, histamine level in the pouch fluid and histidine decarboxylase activity of pouch wall tissues in the postanaphylaxis phase were increased. Although treatment with dexamethasone failed to inhibit histamine release from mast cells in the anaphylaxis phase, histamine production in the postanaphylaxis phase was inhibited dose dependently. Histamine production-increasing activity in the pouch fluid collected 8 h after the Ag challenge, which was estimated by an activity to stimulate histamine production by bone marrow cells, was decreased by the administration of dexamethasone at the time of the Ag challenge. The addition of steroidal antiinflammatory drugs, dexamethasone, prednisolone, or hydrocortisone, into the incubation medium inhibited the pouch fluid-induced histamine production by bone marrow cells. Hydrocortisone mesylate antagonized the inhibitory effect of dexamethasone on histamine production by bone marrow cells. However, hydrocortisone mesylate failed to recover the decrease in histamine production-increasing activity of the pouch fluid collected from dexamethasone-treated rats. In addition, the dialyzed sample of pouch fluid obtained from dexamethasone-treated nonsensitized rats did not reduce the stimulated histamine production by the pouch fluid sample obtained from the sensitized rats. However, increase in histamine production of bone marrow cells stimulated by the pouch fluid was not inhibited by cyclosporin A that inhibited histamine production induced by Con A. This observation indicates that the pouch fluid has no effect to induce production of the histamine production-increasing factor by bone marrow cells. Consequently, it is suggested that dexamethasone inhibits not only the production of histamine production-increasing factor but also the response of histamine-producing cells to this factor.

Suppression by adrenoceptor beta-agonists of vascular permeability increase and edema formation induced by arachidonate metabolites, platelet-activating factor, and tumor-promoting phorbol ester TPA

Air-pouch-type inflammation was induced by injecting sodium carboxymethyl cellulose solution containing leukotriene C4 (LTC4, 3.20 x 10(-7) M, 0.2 micrograms/ml) and prostaglandin E2 (PGE2, 5.68 x 10(-6) M, 2.0 micrograms/ml), platelet-activating factor (PAF, 1 x 10(-6) M, 0.52 micrograms/ml), or 12-O-tetradecanoyl phorbol 13-acetate (TPA, 1.62 x 10(-6) M, 1.0 micrograms/ml) into an air pouch made on the dorsum of rats. Vascular permeability and tissue edema formation were significantly increased by injecting the phlogogen solution. The histamine level in the pouch fluid was dramatically increased by injecting TPA but not by LTC4 and PGE2, or PAF. Injection of isoproterenol or procaterol with the phlogogen solution produced dose-dependent suppression of both vascular permeability increase and tissue edema formation. However, the TPA-induced increase in the histamine level was not suppressed in parallel with the decrease of vascular permeability or tissue edema formation. These results indicate that beta-agonists suppress vascular permeability response and local tissue edema formation not by inhibiting mast cell degranulation, but by inhibiting the reactivity of the local vasculature to chemical mediators such as arachidonate metabolites, PAF, and histamine and serotonin released from mast cells.

Chemotactic activity for neutrophils in allergic inflammation in rats

The number of neutrophils, eosinophils, and mononuclear cells that had migrated into pouch fluid were measured after injecting an antigen (azobenzenearsonate-conjugated acetyl bovine serum albumin) solution into air pouches made on the dorsum of immunized rats. The number of neutrophils began to increase 4 hr after the antigen challenge, reaching a maximum at 16-24 hr. Increases in the number of eosinophils and mononuclear cells were quite poor. The pouch fluid supernatant fraction was fractionated to hydrophilic and lipophilic fractions with the aid of an octadecylsilyl silica cartridge, and the chemotactic activity in each fraction was measured by the modified Boyden chamber method. The chemotactic activity in the pouch fluid supernatant fraction was the highest at 2-4 hr and decreased with time after the antigen challenge. At 16 and 24 hr, chemotactic activity was decreased to a very low level although there was a large number of neutrophils in the pouch fluid. At 4 hr, the chemotactic activity in the lipophilic fraction was significantly higher than that in the hydrophilic fraction. However, at 8 hr, the chemotactic activity in the lipophilic fraction was changed to a significantly lower level than that in the hydrophilic fraction. The chemotactic activity in the lipophilic fraction had decreased to a very low level at 8 hr. Heat treatment of the pouch fluid supernatant fraction at 92 degrees C for 5 min both at 4 and 8 hr significantly increased the chemotactic activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Possible role for platelet-activating factor in neutrophil infiltration in allergic inflammation in rats

Allergic inflammation was induced by injecting an antigen solution into an air pouch made on the dorsum of immunized rats with the antigen azobenzene-arsonate-conjugated acetyl bovine serum albumin. In this model, leukocyte infiltration into the pouch fluid was prominent 4-8 h after the antigen challenge. Most of the infiltrated leukocytes were neutrophils. Administration of the platelet-activating factor (PAF) antagonists such as CV-3988 and L-652,731 into the air pouch 15 min before and at the time of the antigen challenge failed to suppress leukocyte infiltration at 8 h. However, when the PAF antagonist was injected into an air pouch 4 h after the antigen challenge, neutrophil infiltration at 8 h was suppressed in a dose-dependent manner. Combined treatment with the 5-lipoxygenase inhibitor AA861 and the PAF antagonist did not potentiate the effect of the PAF antagonist, suggesting that participation of leukotriene B4 in neutrophil infiltration in this model is negligible. Eosinophil infiltration was very weak at 8 h, and the PAF antagonist showed no significant effect. At 8 h, the PAF level in the serum of the immunized rats was significantly higher than that of the nonimmunized rats. Intravenous administration of the PAF antagonist 15 min before the antigen challenge suppressed leukocyte infiltration more effectively than local administration into the pouch. These results indicate that PAF plays a significant role in neutrophil infiltration in allergic inflammation.

Okadaic acid and dinophysistoxin-1, non-TPA-type tumor promoters, stimulate prostaglandin E2 production in rat peritoneal macrophages

Okadaic acid and dinophysistoxin-1 isolated from a black sponge, Halichondria okadai are non-12-O-tetrade-canoylphorbol 13-acetate (non-TPA)-type tumor promoters of mouse skin. Okadaic acid at concentrations of 10-100 ng/ml stimulated prostaglandin E2 production in rat peritoneal macrophages. Dinophysistoxin-1 (35-methylokadaic acid) stimulated prostaglandin E2 production as strong as okadaic acid, but okadaic acid tetramethyl ether, an inactive compound as a tumor promoter, did not. Okadaic acid at 10 ng/ml (12.4 nM) stimulated prostaglandin E2 production as strongly as TPA at 10 ng/ml (16.2 nM) 20 h after incubation. Unlike TPA-type tumor promoters, okadaic acid required a lag phase before stimulation. The duration of this lag phase was dependent on the concentration of okadaic acid. Indomethacin inhibited okadaic acid-induced preostaglandin E2 production in a dose-dependent manner, and its inhibition was more strongly observed in okadaic acid-induced prostaglandin E2 production. Cycloheximide inhibited okadaic acid-induced release of radioactivity from [3H]arachidonic acid-labeled macrophages and prostaglandin E2 production dose dependently, suggesting that protein synthesis is a prerequisite for the stimulation of arachidonic acid metabolism. These results support our idea that tumor promoters, at very low concentrations, are able to stimulate arachidonic acid metabolism in rat peritoneal macrophages.

Some features of the metastatic cancer cells in prostaglandin production

In order to establish metastatic lesions, 2.5 x 10(6) AH100B cells were injected into the left carotid artery of male Donryu rats. Each metastatic nodule in the liver or kidney, 1 mm or less in diameter, thus obtained was then injected into the peritoneal cavity in which these metastatic cells come to free. About 3 weeks later, each ascites was collected from the rats, while not bloody. Then, cancer cells obtained from each ascites were suspended in Dulbecco's PBS without Ca2+ and Mg2+ (pH 7.2) after washing. Then, 10(6) metastasized or control cancer cells were incubated in 0.1 ml of PBS mentioned above together with 0.1 microCi of (1-14C)-AA at 24 degrees C for 3 min, respectively. After the extraction procedure, AA metabolites formed were separated by means of TLC, and each TLC plate was subjected to autoradiography. In the metastasized cells, PG production ability was generally accelerated and especially in that of PGF2 alpha as compared with that of the control.

Stimulation of histamine release and arachidonic acid metabolism in rat peritoneal mast cells by thapsigargin, a non-TPA-type tumor promoter

Thapsigargin, a non-TPA-type tumor promoter, releases histamine and stimulates arachidonic acid metabolism in rat peritoneal mast cells. In order to clarify the relationship between the histamine-releasing activity and the arachidonic acid metabolism-stimulating activity of thapsigargin in mast cells, the effects of cyclooxygenase inhibitors, indomethacin and ibuprofen, a lipoxygenase inhibitor, AA861, and dual inhibitors for cyclooxygenase and lipoxygenase, nordihydroguaiaretic acid and BW755C, on histamine release and arachidonic acid metabolism were examined. High-performance liquid chromatography analysis revealed that the peritoneal mast cells preferentially produce prostaglandin D2 by thapsigargin treatment. These inhibitors suppressed thapsigargin-induced prostaglandin D2 production in a dose-dependent manner, but failed to inhibit histamine release, suggesting that the mechanisms for stimulation of histamine release by thapsigargin is not dependent on increased arachidonic acid metabolism. Time-course experiments of histamine release and the release of radioactivity from [3H]arachidonic acid-labeled mast cells also provide evidence for a difference in mechanism.

Alpha 1-antitrypsin and hepatic fibrosis

The administration of alpha 1-antitrypsin, both sialo and asialo types, to rats with chronic liver injury accelerated hepatic fibrosis. More fibrosis was seen histologically and the amount of hydroxyproline in the liver increased. Moreover, the growth of HEL cells (human embryonal lung fibroblast) in culture was promoted by alpha 1-antitrypsin though the action of the asialo type was very weak by contrast with the sialo type.

Occurrence of histamine-production-increasing factor in the postanaphylactic phase of allergic inflammation

Experimental study on histamine liberation in a postanaphylactic phase of allergy was carried out employing an air pouch model of allergic inflammation in rats. The antigen used was azobenzenearsonate-conjugated acetyl bovine serum albumin. Synthesis and liberation of histamine took place in the inflammatory pouch in the dorsum of the allergic rats, and brought about a gradual rise in the histamine level in the pouch fluid with a peak at 24 h after the antigen challenge. The time course of the histamine level in the pouch fluid was quite similar to that of histidine decarboxylase activities in the inflammatory tissues. alpha-Fluoromethylhistidine reduced the histamine level in the postanaphylactic phase, although it had been ineffective in the anaphylactic phase. A substance capable of increasing histamine production by bone marrow cells was found in the pouch fluid of allergic rats, while it was absent in the normal rat serum and pouch fluid of nonsensitized rats. The histamine-production-increasing activity rose until 24 h after the antigen challenge, but fell at 48 h in parallel with changes both of histamine levels in the pouch fluid and histidine decarboxylase activity in inflammatory tissues. The histamine-production-increasing factor is thought to be a protein, since it was inactivated by treatment with heat (70 degrees C for 30 min) or trypsin. Its molecular weight was estimated to be between 25,000 and 40,000.

Metabolism of leukotriene C4, D4 and E4 in allergic inflammation in rats

Using an allergic inflammation model of air pouch type in rats, levels of peptide-leukotriene (LT) C4, D4 and E4 in the pouch fluid were measured chromatographically, and peptide-LT metabolizing activities in the pouch fluid in the anaphylactic phase were examined. 10 min after injection of an antigen (azobenzene arsonate-conjugated acetyl bovine serum albumin) solution into a preformed air pouch on the back of the immunized rats, LTC4 level in the pouch fluid was the highest, followed by LTD4 and LTE4. At 30 min, the order of the level was reversed to LTE4 greater than LTD4 greater than LTC4, and total amount of peptide-LTs (LTC4 + LTD4 + LTE4) was the highest. Supernatant fraction of the pouch fluid collected 30 min after the antigenic challenge, converted [3H]LTC4 into [3H]LTD4, and [3H]LTD4 into [3H]LTE4 in time- and concentration-dependent manner. [3H]LTE4 was not metabolized under these conditions. Heat denaturation of the pouch fluid diminished the conversion of [3H]LTC4 into [3H]LTD4, and [3H]LTD4 into [3H]LTE4. In the granule fraction of purified mast cells, no metabolic activity of [3H]LTs was found. In intact mast cells as well as degranulating mast cells, a small but significant amount of [3H]LTC4 was metabolized into [3H]LTD4 and [3H]LTE4. In contrast, rat serum showed potent metabolizing activities of peptide-LTs. Since plasma exudation into the pouch is very prominent in the anaphylactic phase in this model, peptide-LT metabolizing activities in the pouch fluid are suggested to be attributable to plasma leaked into the pouch during the anaphylactic phase.

Inhibition by gossypol of tumor promoter-induced arachidonic acid metabolism in rat peritoneal macrophages

Rat peritoneal macrophages were prelabeled with [3H]arachidonic acid. The release of radioactivity into the medium was increased by treatment with TPA-type tumor promoters, such as TPA, teleocidin and aplysiatoxin, and the non-TPA-type tumor promoter, thapsigargin. Gossypol, at concentrations of 3 and 10 microM, inhibited the release of radioactivity stimulated by both types of tumor promoter, although the mechanism of stimulation of arachidonic acid metabolism is different in the two types of tumor promoter. Stimulation of prostaglandin E2 production by these tumor promoters was also inhibited by treatment with gossypol. Calcium ionophore A23187-stimulated release of radioactivity and prostaglandin E2 production were also inhibited by gossypol treatment. The mechanism of inhibition by gossypol of prostaglandin E2 production is discussed.

Analysis of the stimulative effect of thapsigargin, a non-TPA-type tumour promoter, on arachidonic acid metabolism in rat peritoneal macrophages

1. At concentrations above 10 ng ml-1, the tumour promoter thapsigargin stimulates the release of radioactivity from [3H]-arachidonic acid-labelled macrophages harvested from rat peritoneal cavity. 2. The release of radioactivity from prelabelled macrophages was augmented more than additively when the cells were incubated in the medium containing both thapsigargin (10 ng ml-1) and other tumour promoters (10 ng ml-1), such as 12-O-tetradecanoylphorbol-13-acetate (TPA), teleocidin and aplysiatoxin. 3. Thapsigargin required extracellular Ca2+ for the stimulation of arachidonic acid release, while TPA did not. 4. Cytoplasmic free calcium level was increased by thapsigargin treatment but not by TPA treatment. 5. An inhibitor of protein kinases, H-7 inhibited the effect of TPA dose-dependently, whereas H-7 did not inhibit that of thapsigargin. 6. These results suggest that thapsigargin stimulates arachidonic acid release by a mechanism different from that of TPA, viz by acting as a selective Ca2+ mobilizer, but not by activating protein kinase C as TPA does.

Three-dimensional reconstruction of semi-gross biostructures using 'macroserials'--1-mm-thick serial organ slices

A method for reconstructing a gross or semi-gross organ structure was developed in a pathological analysis of liver lobes surgically excised from patients with bile duct carcinoma, where the extent of the tumour was to be demonstrated three-dimensionally. Fixed material was serially sliced with a ham-slicer, producing flawless slices as thin as 1 mm. Prior to slicing, the material was temporarily 'embedded' in gelatine to hold it in shape throughout slicing. These slices ('macroserials') could be directly brought into macroscopic 3-D reconstruction, but in the case of bile duct carcinoma, microscopic examination of the slices was indispensable in determining the extent of carcinoma and precarcinomatous (dysplastic) changes. Slices 1 mm thick were embedded in paraffin using a special holder made of plywood plates which kept a slice in a flat, extended state through the dehydration process. This method of preparing thin slices not only allows the reconstruction of a gross organ structure with less effort than before, but also ensures a certain amount of accuracy in the reproduction of submacroscopic structures.

Mechanism of the inhibitory action of cyclooxygenase inhibitors on leukocyte infiltration: involvement of endogenous histamine

The mechanism of the inhibitory action of cyclooxygenase inhibitors on leukocyte accumulation in the inflammatory locus was investigated in an allergic inflammation of the air pouch types in rats. Three kinds of cyclooxygenase inhibitors, indomethacin, diclofenac and tiaprofenic acid, caused not only inhibition of the vascular permeability response and leukocyte accumulation but also elevation of histamine levels in the exudate. These effects of indomethacin were all reversed by local administration of prostaglandin E2. Pyrilamine, an H1 antagonist, did not affect the anti-inflammatory actions of indomethacin. The H2 antagonists, cimetidine, ranitidine and famotidine, decreased the inhibitory effect of indomethacin on leukocyte accumulation without affecting the inhibitory action on vascular permeability. These results indicate that the inhibitory action of cyclooxygenase inhibitors on leukocyte accumulation is derived from their blocking effect against generation of PGE2 which works as an inhibitory factor on the production of histamine in the inflammatory tissues.

Analysis of tumor-promoter-induced inflammation in rats: participation of histamine and prostaglandin E2

Inflammatory reactions induced by TPA (12-O-tetradecanoylphorbol 13-acetate)-type tumor promoters, including TPA, teleocidin and aplysiatoxin, and chemical mediators responsible for such inflammatory reactions were analyzed. The tumor promoter dissolved in a 0.8% sodium carboxymethyl cellulose solution was injected into a subcutaneous air pouch preformed on the dorsum of rats. Within 30 min after the injection, vascular permeability as measured by the leakage of labeled albumin into the pouch fluid was increased, with a concomitant increase in histamine level. This increase in vascular permeability was inhibited by a histamine antagonist, pyrilamine, and a serotonin antagonist, methysergide. Vascular permeability at 4 h was not inhibited by pyrilamine or methysergide but was inhibited by a cyclooxygenase inhibitor, indomethacin, with a parallel decrease in the prostaglandin E2 level in the pouch fluid. These results suggest that the TPA-type tumor promoters induce inflammation by the mechanism of mast cell degranulation within a short period, this being followed by the stimulation of arachidonic acid metabolism. The mechanism of the in vivo effect of the TPA-type tumor promoters is discussed and compared with in vitro effects that we have previously reported.

The effect of diphenylamine derivatives on arachidonic acid metabolism in rat peritoneal macrophages

The effect of diphenylamine derivatives such as diclofenac sodium, mefenamic acid and lobenzarit disodium on arachidonic acid metabolism in rat peritoneal macrophages was examined. Lobenzarit disodium has no effect on prostaglandin E2 production as measured by radioimmunoassay although two other diphenylamine derivatives have a potent inhibitory activity. Three diphenylamine derivatives have no effect on Ca2+ ionophore-stimulated release of radioactivity from (3H)arachidonic acid-labeled macrophages. HPLC analysis revealed that lobenzarit disodium had no effect on the synthesis of lipoxygenase products as observed in diclofenac sodium and mefenamic acid. It is concluded that lobenzarit disodium, although its fundamental chemical structure resembles diclofenac sodium and mefenamic acid, has no inhibitory activity on arachidonic acid metabolism, suggesting that immunomodulatory activities of lobenzarit disodium are manifested without interfering with arachidonic acid metabolism.

Stimulation of arachidonic acid metabolism in rat peritoneal macrophages by thapsigargin, a non-(12-O-tetradecanoylphorbol-13-acetate) (TPA)-type tumor promoter

The effects of thapsigargin, which is a histamine secretagogue and has recently been found to be a non-(12-O-tetradecanoylphorbol-13-acetate) (TPA)-type tumor promoter in two-stage carcinogenesis using mouse skin, on arachidonic acid metabolism in rat peritoneal macrophages were examined. The release of radioactivity from 3H arachidonic acid-labeled macrophages was increased at doses more than 10 ng/ml. Prostaglandin E2 production was also increased dose-dependently without inducing prominent changes in cell morphology. The potency to stimulate prostaglandin E2 production by thapsigargin was stronger than that by TPA at a dose of 10 ng/ml when measured 6 h after the incubation. HPLC analysis revealed that thapsigargin stimulated the production of lipoxygenase products such as leukotriene B4 and 12-hydroxyeicosatetraenoic acid as well as cyclooxygenase products such as prostaglandin E2 and 6-keto prostaglandin F 1 alpha. Thapsigargin, an analogue of thapsigargin, also stimulated prostaglandin E2 production. The mechanism of the action of thapsigargin was discussed. It was confirmed that the tumor promoters are associated with the activity to stimulate arachidonic acid metabolism irrespective of their type, TPA-type or non-TPA-type.

Role of endogenous histamine in postanaphylactic phase of allergic inflammation in rats

Role of endogenous histamine in postanaphylactic phase of allergic inflammation was examined by using a rat model of allergic inflammation of air pouch type. Histamine in the exudate revealed a biphasic increase. The anaphylactic increase was followed by rapid decrease and then by a gradual rising in postanaphylactic phase with the maximum attained around 24 hr after the antigenic challenge. It again decreased gradually. The histamine increase in the postanaphylactic phase was accompanied by the increase of histidine decarboxylase activity in inflammatory tissues. Local administration of pyrilamine, an H1 antagonist, together with either methysergide, a serotonin antagonist, or cimetidine, an H2 antagonist, was unable to inhibit vascular permeability response in the postanaphylactic phase. When histaminase was administered locally in the postanaphylactic phase to reduce histamine in the exudate, neutrophil accumulation in the exudate was enhanced without any change in exudate accumulation. Enhancement of the neutrophil accumulation was also inducible with local administration of cimetidine but not with pyrilamine. Local administration of histamine inhibited the neutrophil accumulation dose-dependently. These results suggest that endogenous histamine released in the postanaphylactic phase contributes to downward regulation of neutrophil accumulation in the inflammatory site without affecting the vascular permeability.

Mechanism of antianaphylactic action of beta-agonists in allergic inflammation of air pouch type in rats

Using an experimental model of allergic inflammation of air pouch type in rats, the mechanism of antiallergic action of beta-agonists was examined. In this model an immediate increase in vascular permeability and histamine level in the pouch fluid was observed after injecting the antigen (azobenzene arsonate-conjugated acetyl bovine serum albumin) solution into the preformed air pouch on the back of the sensitized rats. The same type of reaction was inducible by injecting anti-rat IgE into the preformed air pouch, but not IgG2a. This fact indicates that the immediate increase in vascular permeability and histamine level is an IgE-mediated anaphylactic reaction. When beta-agonists such as isoproterenol, procaterol and salbutamol were injected into the air pouch together with the antigen, the anaphylactic increase in vascular permeability was suppressed dose-dependently without concomitant decrease in histamine level in the pouch fluid. In contrast, disodium cromoglycate, an inhibitor of degranulation of mast cells, the anaphylactic vascular permeability increase was suppressed in parallel with a decrease of the histamine level. Propranolol, a beta-antagonist, counteracted the effect of beta-agonists. Serotonin-induced vascular permeability was also suppressed dose-dependently by treatment with beta-agonists. Furthermore, vascular permeability in the postanaphylactic phase of the present experimental model was also suppressed by isoproterenol. These results indicate that beta-agonists exert their antiallergic effect by inhibiting the reactivity of local vasculature to chemical mediators released from mast cells.

Platelet-activating factor in the inflammatory exudate in the anaphylactic phase of allergic inflammation in rats

Using a model of allergic inflammation of air pouch type in rats, the platelet-activating factor (PAF) in the pouch fluid in the anaphylactic phase was analyzed. Anaphylactic reaction was induced by injecting an antigen (azobenzene-arsonate-conjugated acetyl bovine serum albumin) solution into a subcutaneous air pouch preformed on the dorsum of immunized rats. The pouch fluid was collected 30 min after the antigenic challenge, and chloroform extract was subjected to normal phase high-performance liquid chromatography to isolate two fractions, PAF and lyso-PAF. In the pouch fluid, however, there was little activity of PAF as examined by the aggregation of guinea pig platelets. The lyso-PAF fraction obtained was acetylated to PAF chemically with pyridine and acetic anhydride. This acetylated lyso-PAF fraction induced the aggregation of guinea pig platelets, which was inhibited dose-dependently by a PAF antagonist, CV-3988. The amount of lyso-PAF in the pouch fluid of the immunized group in the anaphylactic phase was significantly higher than that of the nonimmunized group. When (3H-)PAF was incubated with the supernatant fraction of the pouch fluid it was metabolized into lyso-PAF time-dependently. The significance of the higher level of lyso-PAF in the pouch fluid in the anaphylactic phase of allergic inflammation is discussed.

Recurrence of an allergic inflammation of air-pouch type in rats and possible participation of prostaglandin E2

The recurrence of allergic inflammation, as examined by exudate accumulation, infiltration of polymorphonuclear leukocytes into the exudate, edema formation, vascular permeability and prostaglandin E2 levels in the exudate, was induced by injecting the antigen, azobenzene arsonate-conjugated acetyl bovine serum albumin, into the capsule of the proliferative granulation tissue which had been formed by the first-time antigenic challenge injection into an air pouch in the dorsum of the sensitized rat. The recurrence of the allergic inflammation 4 and 24 h after the antigenic challenge was inhibited dose-dependently by treatment with cyclooxygenase inhibitors, suggesting the possible participation of cyclooxygenase products, especially prostaglandin E2. The difference in the allergic inflammatory responses induced by the first-time antigenic challenge and the second-time antigenic challenge was discussed from the viewpoint of chemical mediators.

Orosomucoid as the accelerator of hepatic fibrosis

The administration of orosomucoid to rats with chronic liver injury accelerated hepatic fibrosis. An increase of hepatic fibres was seen histologically and the content of hydroxyproline in the liver collagen fraction increased. Moreover, the incorporation of 3H-proline into the collagen fraction of injured liver was increased by the administration of orosomucoid.

Synergistic stimulation of histamine release from rat peritoneal mast cells by 12-O-tetradecanoylphorbol 13-acetate (TPA)-type and non-TPA-type tumor promoters

Thapsigargin, a non-TPA (12-O-tetradecanoylphorbol 13-acetate)-type tumor promoter, provoked histamine release from rat peritoneal mast cells at concentrations above 30 ng/ml, but not at 10 ng/ml. TPA-type tumor promoters such as TPA, teleocidin and aplysiatoxin released very little, if any, histamine even at 100 ng/ml. When mast cells were incubated in medium containing thapsigargin at 10 ng/ml and varying concentrations of TPA-type tumor promoters, histamine release was increased synergistically. Maximum synergistic effects were observed at 10 ng/ml of each TPA-type tumor promoter. Palytoxin, another non-TPA-type tumor promoter, having no effect on histamine release at up to 10 pg/ml, also induced histamine release in the presence of 10 ng/ml of each TPA-type tumor promoter. However, no synergistic effect on histamine release was observed when mast cells were incubated in medium containing two different non-TPA-type tumor promoters, e.g., 10 ng/ml thapsigargin and 10 pg/ml palytoxin, or in medium containing two different TPA-type tumor promoters, e.g., TPA and teleocidin, TPA and aplysiatoxin, or teleocidin and aplysiatoxin (all at 10 ng/ml). These results suggest that the release of histamine from mast cells is stimulated synergistically under the mutual influence of TPA-type tumor promoters and non-TPA-type tumor promoters.

Vascular permeability responses and the role of prostaglandin E2 in an experimental allergic inflammation of air pouch type in rats

Rats were sensitized with azobenzene arsonate-conjugated acetyl bovine serum albumin. An allergic inflammation was induced in the preformed air pouch in the dorsum of the sensitized rats by injecting the antigen dissolved in a 2% sodium carboxymethyl cellulose solution into the air pouch. Time course changes of vascular permeability, accumulated pouch fluid volume and prostaglandin E2 (PGE2) levels in the pouch fluid were compared in sensitized and non-sensitized rats to characterize the allergic inflammatory reaction. Effects of three cyclo-oxygenase inhibitors (indomethacin, diclofenac sodium and tiaprofenic acid) on vascular permeability and accumulated pouch fluid volume 4 and 24 h after the immunological challenge injection were examined to elucidate a possible role of PGE2 in the inflammatory response. Four h after initiating the allergic reaction, although the level of PGE2 in the pouch fluid reached a high level, the vascular permeability response, measured over the period 3.5-4 h, was not suppressed by treatment with the three cyclo-oxygenase inhibitors and neither was the pouch fluid volume measured over the period 0-4 h. However, vascular permeability and accumulated pouch fluid volume at 24 h were suppressed by the cyclo-oxygenase inhibitors in a dose-dependent manner. These observations suggest that in this model, endogenous PGE2 does not affect oedema formation measured at 4 h. However, oedema formation measured at 24 h may be dependent on PGE2 generation.

Pharmacological analysis of the vascular permeability response in the anaphylactic phase of allergic inflammation in rats

Allergic inflammation was induced by injecting an antigen (azobenzenearsonate-conjugated acetyl bovine serum albumin) solution into a preformed air pouch in the dorsum of sensitized rats. There was a marked increase of vascular permeability during the first 30 min, i.e. the anaphylactic phase, after the antigenic challenge injection. In an attempt to define the mediators responsible for the vascular permeability increase, series of experiments were performed with the aid of various pharmacologic agents. The combined treatment with pyrilamine and methysergide almost completely suppressed the anaphylactic vascular permeability response. However, FPL 55712, a specific antagonist to leukotrienes C4 and D4, components of slow-reacting substance, exerted no effect at doses sufficient to suppress the leukotriene C4-or leukotriene D4-induced vascular permeability increase. Indomethacin treatment was also ineffective. These results suggest that the anaphylactic increase in vascular permeability was mediated primarily by histamine and serotonin, while slow-reacting substance or prostaglandins did not play any significant role. A potent anti-inflammatory steroid, dexamethasone, exerted a dose-dependent inhibitory effect on the anaphylactic increase in vascular permeability without interfering with the liberation of histamine from mast cells. The mechanism of the steroid action is discussed.

Antiinflammatory actions of ephedrines in acute inflammations1

Ephedrine (EP), pseudoephedrine (PEP), ephedroxane (EX) and pseudoephedroxane (PEX) inhibited carrageenin-induced hind-paw edema in sham-operated mice as well as adrenalectomized mice. Hind-paw edema induced by histamine, serotonin, bradykinin and prostaglandin E (1) was suppressed by these alkaloids, showing that they exert the antiinflammatory activity at the early exudative stage of inflammation. Although tolazoline and propranolol had no effects on the inhibitory activity of EX and PEX, treatment with tolazoline decreased the antiinflammatory activity of EP and PEP on carrageenin-induced hind-paw edema. Antiinflammatory activity of PEP was reduced by previous treatment with reserpine, indicating the antiinflammatory activity of EP and PEP to be partly concerned with the sympathetic nervous system. Although these alkaloids injected I.C.V. elicited no antiinflammatory actions on carrageenin-induced hind-paw edema and the inhibitory activity of morphine on carrageenin-induced hind-paw edema was potentiated by the concurrent administration of PEP and EX, demonstrating that the mechanism of antiinflammatory activity does not involve the central nervous system. Further, these alkaloids inhibited prostaglandin E (2) biosynthesis.

Stimulation of prostaglandin E2 production by 12-O-tetradecanoylphorbol 13-acetate (TPA)-type and non-TPA-type tumor promoters in macrophages and its inhibition by cycloheximide

The effects of TPA (12-O-tetradecanoylphorbol 13-acetate)-type and non-TPA-type tumor promoters on prostaglandin E2 production by peritoneal macrophages of rats were examined. Among the TPA-type tumor promoters, aplysiatoxin was most potent in stimulating prostaglandin E2 production followed by dihydroteleocidin B, teleocidin, TPA and debromoaplysiatoxin. Prostaglandin E2 production by aplysiatoxin treatment was stimulated at doses up to 0.1 ng/ml. Palytoxin, a non-TPA-type tumor promoter, also stimulated both prostaglandin E2 production and the release of radioactivity from [3H]arachidonic acid-labeled macrophages. However, the dose required for the expression of these effects by palytoxin was up to 3 pg/ml. It was suggested that the tumor promoters are associated with the activity to stimulate arachidonic acid metabolism, irrespective of their type. Cycloheximide, a protein synthesis inhibitor, inhibited both prostaglandin E2 production and the release of radioactivity from prelabeled macrophages stimulated either by the TPA-type tumor promoters or by the non-TPA-type tumor promoter. It is possible that the tumor promoters may induce the synthesis of some proteins responsible for the stimulation of arachidonate metabolism.

Lectins modulate prostaglandin E2 production by rat peritoneal macrophages

The effect of Aloctin A (Alo A), a lectin having anti-inflammatory activities, on prostaglandin (PG) E2 production by activated rat peritoneal macrophages was compared with that of concanavalin A (Con A), wheat germ agglutinin (WGA), plsum sativum agglutinin (PSA) and soybean agglutinin (SBA). Alo A, WGA, Con A and PSA at 10 micrograms per ml inhibited PG E2 production. But SBA, even at a dose of 1 microgram per ml, stimulated PG E2 production. The inhibition by Alo A treatment of the release of radioactivity from (3H)arachidonic acid-labeled macrophages and the stimulation of this release by SBA treatment were observed. The uptake of (51Cr)-labeled sheep red blood cells by the macrophage was inhibited by Alo A, Con A, and PSA, all at 10 micrograms per ml and SBA at 1 microgram per ml, however, WGA at 10 micrograms per ml stimulated the uptake of the sheep red blood cells. The mechanism of the anti-inflammatory properties of Alo A was discussed.

Reduction by dexamethasone of chemotactic activity in inflammatory exudates

Using an experimental model for allergic inflammation of the air pouch type in rats, the effects of dexamethasone and indomethacin on leukocyte infiltration and level of chemotactic activity in the inflammatory exudate were examined to clarify the mechanisms of anti-inflammatory effects of glucocorticoids. Both dexamethasone and indomethacin when locally administered inhibited leukocyte infiltration, while chemotactic activity of the exudate was reduced by dexamethasone only. Indomethacin failed to reduce the level of chemotactic activity. Suppression by dexamethasone of the level of chemotactic activity became evident prior to the decrease in the number of leukocytes in the inflammatory exudate. These results suggest that the anti-inflammatory steroids manifest their inhibitory effect on leukocyte infiltration by inhibiting the generation of chemotactic factors in the inflammatory site. Besides this, the possible production of some inhibitory factors by the steroids may be considered as an alternative mechanism.

Dexamethasone inhibits generation in inflammatory sites of the chemotactic activity attributable to leukotriene B4

Effects of dexamethasone on chemotactic activity to polymorphonuclear leukocytes (PMN) of a lipophilic fraction collected with the aid of octadecylsilyl silica cartridge from exudates of an allergic inflammation were investigated. The chemotactic activity of this fraction was attributable to leukotriene B4 fraction separated by means of a reversed phase high performance liquid chromatography. Local application of dexamethasone suppressed dose-dependently the chemotactic activity of the lipophilic fraction in parallel with the inhibition of PMN infiltration in the inflammatory sites.

Arachidonate metabolites in acute and chronic allergic air pouch inflammation in rats and the anti-inflammatory effects of indomethacin and dexamethasone

Two types of allergic air pouch inflammation, the acute and the chronic types, were induced in the dorsum of rats. 1, 8, and 24 h after the immunologic challenge injection, the exudate contents of cyclooxygenase products, prostaglandin (PG)E2, 13,14-dihydro-15-keto-PGE2, PGI2 (measured as 6-keto-PGF1 alpha) and PGD2, and the lipoxygenase products, hydroxyeicosatetraenoic acids (HETEs) and 6-sulfido-peptide-containing leukotrienes (SRS) were measured by radioimmunoassay. The effects of locally injected indomethacin or dexamethasone on the exudate volumes and the number of cells in the exudates in both types of allergic inflammation and the effects of these drugs on the contents of the cyclooxygenase and lipoxygenase products in the exudates 8 h after the challenge injection were examined.

Inhibition by AA861 of prostaglandin E2 production by activated peritoneal macrophages of rat

Prostaglandin E2 production by rat peritoneal activated macrophages was inhibited by AA861 which had been reported as a selective inhibitor of 5-lipoxygenase from guinea pig peritoneal leukocytes. At a dose of 3.06 microM, prostaglandin E2 production was decreased to 27% of control. No inhibition of the release of (3H)arachidonic acid from the prelabeled macrophages was observed at the dose.

Slow reacting substance in the exudate of allergic air pouch inflammation in rats

The activity of slow reacting substance was examined in the exudate of the allergic inflammation in rats after partial purification by alkaline decomposition and XAD-8 anion-exchange column chromatography. The guinea-pig ileum contractile substance from the exudate collected at 1 hr after the challenge injection was attributed to leukotriene (LT) C4 and/or D4 since the activity was selectively antagonized by FPL 55712. Participations of histamine, acetylcholine and prostaglandin E2 were ruled out. However, the contraction pattern due to the partially purified substance collected at 24 hr after the challenge injection was different from that at 1 hr. The guinea-pig ileum was contracted much more slowly than by synthetic LT C4 or D4 and this contraction was not antagonized by FPL 55712. It was demonstrated that some unidentified materials exist in the exudate of the allergic air pouch inflammation which contract isolated guinea-pig ileum in a different manner from synthetic LT C4 or D4.

Correlation of leukocyte accumulation with chemotactic activity in the exudate of an allergic air-pouch inflammation

Chemotactic activity at the site of an allergic air-pouch inflammation induced with azobenzene-arsonate-conjugated acetyl bovine serum albumin as an antigen was studied and a close correlation of the chemotactic activity with the intensity of leukocyte migration was demonstrated. In the period of vigorous leukocyte immigration into the fluid in the allergic air-pouch, chemotactic activity of the exudate was maintained at a high level, while no significant activity was detected after the number of leukocytes in the pouch fluid reached maximum.

Phospholipase A2 activity in carrageenin-induced inflammatory tissue of rats

Phospholipase A2 activity was detected in 7-day-old carrageenin-induced inflammatory tissue of rats using a synthetic substrate. 1-acyl-2-[3H]arachidonyl-phosphatidylcholine. The inflammatory tissue was homogenized in saline containing 1 M KCl, and the 105,000 g supernatant fraction was placed on a Sephadex G-100 column. The partially purified phospholipase A2 had a pH optimum at 6-7 and was Ca2+ dependent. p-Bromophenacyl bromide was strongly inhibitory to the partially purified phospholipase A2 (IC50 = 1.44 x 10(-5) M). A moderate inhibition was observed with indomethacin. Cycloheximide and dexamethasone, which inhibit prostaglandin production in inflammatory tissue, exerted no direct inhibitory action on the phospholipase A2. There were no direct inhibitory effects of quinacrine, bradykinin, or actinomycin D. The cell-free supernatant fraction of the inflammatory exudate of 7-day-old carrageenin-induced granulation tissue was found to have no phospholipase A2 activity.

Mechanism of inhibitory action of mesaconitine in acute inflammations

Mesaconitine (MA) inhibited carrageenin-induced hind-paw edema in sham-operated mice as well as adrenalectomized mice. Hind-paw edema produced by subplantar injection of histamine, serotonin and prostaglandin E1 was suppressed by MA, indicating that it elicits the antiinflammatory activity at the early exudative stage of inflammations. However, MA did not affect the biosynthesis of the prostaglandins. Trazoline and propranolol had no effect on the inhibitory activity of MA on carrageenin-induced hind-paw edema. MA when administered i.c. at the doses where it shows marked analgesic activity produced dose-dependent antiinflammatory responses on paw edema produced by carrageenin and on vascular permeability accelerated by acetic acid and agar. The inhibitory activity of morphine on carrageenin-induced paw edema failed to be potentiated by the concurrent administration of MA, demonstrating that the mechanism of the antiinflammatory activity of MA involves the central nervous system.

Induction of a delayed type hypersensitivity to carrageenin in mice

Induction of delayed type hypersensitivity to carrageenin in mice was investigated with successful results. Male ddY/s mice were immunized with 1 mg of carrageenin 100 microliters of Freund's complete adjuvant-saline (1:1) emulsion and challenged 10 d after the immunization on their footpads with either 10 or 40 micrograms of the antigen in 2.5 microliters of Freund's incomplete adjuvant-saline (1:1) emulsion. The mice exhibited a strong allergic footpad reaction at 24-48 h after the challenge injection. The footpad reaction was successfully transferred with spleen cells. Non-steroidal antiinflammatory drug, indomethacin, and steroidal antiinflammatory drug, dexamethasone, suppressed the delayed type hypersensitivity reaction.

A possible role of arachidonate metabolism in allergic air pouch inflammation in rats. Anti-inflammatory effect of indomethacin and dexamethasone and the level of prostaglandin E2 in the exudate

The effect of indomethacin and dexamethasone on an allergic inflammation in rats, a novel model of allergic inflammation of an air pouch type, was examined. Indomethacin and dexamethasone exerted a dose-dependent inhibition of both the accumulation of inflammatory exudate and the migration of leukocytes into the exudate. And although prostaglandin E2 levels in the exudate were lowered to the same extent by treatment with indomethacin and dexamethasone, inhibition of both exudate accumulation and and leukocyte migration was more pronounced after treatment with dexamethasone. The difference in the effectiveness of indomethacin and dexamethasone in terms of inhibition of arachidonate metabolism in the allergic air pouch inflammation are discussed.

Induction of an allergic air-pouch inflammation in rats

An allergic air pouch inflammation was induced on the dorsum of rats using azobenzenearsonate-conjugated acetyl bovine serum albumin as an antigen. Rats were immunized by intradermal injection with 5 mg of the antigen in 0.5 ml Freund's complete adjuvant saline (1:1) emulsion. 9 days after the immunization 8 ml of air was injected subcutaneously on the dorsum, and 24 h later 4 ml of 2% sodium carboxymethyl cellulose solution containing 2 mg of the antigen was injected into the preformed air pouch to provoke the allergic inflammation. In addition to the histological observations of the inflammatory tissues of the pouch wall, time course studies on the volume of the inflammatory pouch fluid, on the number and species of inflammatory cells in the pouch fluid and on the wet weight of granulation tissues were carried out to characterize the nature of the inflammatory reaction, which was shown to be suitable as a model to perform quantitative measurements and biochemical analyses of the allergic inflammation.

Glycyrrhizin inhibits prostaglandin E2 production by activated peritoneal macrophages from rats

Glycyrrhizin was found to inhibit prostaglandin E2 production by activated rat peritoneal macrophages. Preincubation of the cells with glycyrrhizin increases its inhibitory effectiveness. Glycyrrhetinic acid, the aglycone of glycyrrhizin, at a dose of 100 microgram per ml also inhibited prostaglandin E2 production, but the inhibition was considered to be attributable to a toxic effect on the cells since more than 30% of the cells were detached from the dish during the 8 hr incubation period. In contrast, glycyrrhizin did not detach the cells from the dish at doses up to 3 mg per ml. Release of [3H]arachidonic acid from prelabeled cells was also inhibited by glycyrrhizin. It is likely that anti-inflammatory activity of glycyrrhizin depends at least in part on its inhibitory effect of the production of prostaglandin E2.

Change of prostaglandin E level in joint fluids after treatment with flurbiprofen in patients with rheumatoid arthritis and osteoarthritis

The prostaglandin E (PGE) level in the knee joint fluid was determined by radioimmunoassay before and after anti-inflammatory therapy with flurbiprofen in 8 patients with rheumatoid arthritis (RA) and 4 patients with osteoarthritis (OA). The level of PGE in RA joint fluids before the anti-inflammatory treatment was 9.5-1.2 ng/ml and in proportion with the leucocyte count in the joint fluid. A marked decrease of the PGE level was attained with flurbiprofen treatment in 4 patients whose initial PGE levels had been higher than 3.2 ng/ml, while 4 patients with lower PGE levels, namely, 1.4-1.2 ng/ml, did not respond to the drug treatment. In all the OA patients the PGE levels was no higher than 1.5 ng/ml and refractory to the anti-inflammatory therapy.

Suppression by dexamethasone of vascular permeability responses induced with leukotrienes C and D in the rat skin

The present experiment was designed to investigate whether glucocorticoids counteract proinflammatory action of leukotrienes C and D which were suggested to play an important role as mediators in the inflammatory exudate response. Vascular permeability was measured using 131I-labeled human serum albumin (131I-HSA) as a tracer. The vascular permeability was elevated promptly after intradermal injection of chemically synthesized leukotriene C or D and then rapidly fell down to the control level. A positive dose-response relationship was observed in the dose levels of 0.01-1 microgram of leukotrienes. Dexamethasone at doses of 0.15, 0.5 and 1.5 mg/kg caused dose-dependent suppression of vascular permeability response induced with leukotrienes C and D. The present data indicate that glucocorticoids are capable of exerting direct inhibitory effect against proinflammatory action of leukotrienes C and D produced through phospholipase A2-arachidonate-lipoxygenase pathway.

Delayed-type hypersensitivity as revealed on the footpads of mice to azobenzenearsonate-acetyl bovine serum albumin

A strong delayed-type footpad reaction was established in mice using azobenzenearsonate-acetyl bovine serum albumin (ABA-AcBSA) as an antigen. Male ddY/S mice were sensitized by subcutaneous injection of 100 microliter of Freund's complete adjuvant - saline (1:1) emulsion containing 100 microgram of the antigen and challenged by subcutaneous injection of 2.5 microliter of Freund's incomplete adjuvant - saline (1:1) emulsion with 2.5 microgram antigen in the footpad on the 10th day after the sensitization. The analysis of the system which fulfilled criteria for delayed-type hypersensitivity with regard to kinetics, passive transfer and histology of the footpad reaction, and the effect of dexamethasone, indomethacin and quinacrine on the footpad reaction were described.

Prostaglandin production by minced carrageenin granuloma tissue of rats and its inhibition by dexamethasone and cycloheximide

Seven-day-old carrageenin granuloma tissue of rats, when incubated in organ culture, produced 6-keto-prostaglandin F1 alpha, prostaglandin E2, prostaglandin F2 alpha, and thromboxane B2 in ratios of 16/7/1/1, respectively. Indomethacin (1 microgram/ml) inhibited this cyclooxygenase-mediated arachidonic acid metabolism. Dexamethasone (1 microgram/ml) also inhibited this metabolic cascade. Its inhibitory effect was not immediate; preincubation of the tissue with dexamethasone potentiated its inhibitory effectiveness. Cycloheximide (0.1 to 10 microgram/ml) also inhibited prostaglandin production. The inhibitory mechanism by cycloheximide of prostaglandin production was discussed in relation to that by dexamethasone.