The Arthus reaction in rats, a possible test for anti-inflammatory and antiheumatic drugs

Synthesis of novel nonsteroidal anti-inflammatory galloyl β-sitosterol-loaded lignin-capped Ag-based drug

Biocompatible anti-inflammatory lignin-capped Ag (LCAg) nanoparticles (NPs) were synthesized for the delivery of galloyl β-sitosterol (Galloyl-BS). β-Sitosterol (BS) is effective against inflammatory responses, like cancer-induced inflammations. BS was modified via gallic acid esterification to enhance its anti-inflammatory potential. LCAg NPs were synthesized by a green method and loaded with galloyl-BS. For comparison, pure BS was also loaded onto LCAg NPs in a separate assembly. The antioxidant potential of Galloyl-BS was greater (IC50 177 µM) than pure BS. Materials were characterized by FT-IR, SEM, XRD, and Zeta potential. Using UV-Vis spectroscopy, drug release experiments were performed by varying pH, time, concentration, and temperature. Maximum drug release was observed after 18 h at pH 6 and 40 °C. Galloyl-BS showed improved drug loading efficiency, release %age, and antioxidant activity compared to pure BS when loaded onto LCAg NPs. DLCAg exhibited excellent anti-inflammatory activity in rat models. These findings indicate that galloyl-BS (drug)-loaded LCAg (DLCAg) NPs have the potential as an anti-inflammatory agent without any prior release and scavenging in normal cells.

Anti-Inflammatory Potential of Pteropodine in Rodents

Pteropodine (PT) is a component of some plants with potentially useful pharmacological activities for humans. This compound has biomedical properties related to the modulation of the immune system, nervous system, and inflammatory processes. This study addresses the anti-inflammatory and antioxidant capacity of pteropodin in a murine model of arthritis and induced edema of the mouse ear. To evaluate the anti-inflammatory activity, we used the reversed passive Arthus reaction (RPAR), which includes the rat paw edema test, the rat pleurisy test, and a mouse ear edema model. The antioxidant effect of PT was evaluated by determining the myeloperoxidase enzyme activity. PT showed an anti-inflammatory effect in the different specific and non-specific tests. We found a 51, 66 and 70% inhibitory effect of 10, 20 and 40 mg/kg of PT, respectively, in the rat paw edema test. In the pleurisy assay, 40 mg/kg of PT induced a low neutrophil count (up to 36%) when compared to the negative control group, and 20 mg/kg of PT increased the content of lymphocytes by up to 28% and the pleural exudate volume decreased by 52% when compared to the negative control group, respectively. We also found an 81.4% inflammatory inhibition of the edema ear with 0.04 mg/ear of PT, and a significant myeloperoxidase enzyme inhibition by the three doses of PT tested. We conclude that PT exerted a potent anti-inflammatory effect in the acute inflammation model in rodents.

EVALUATION OF THE ANTI-INFLAMMATORY CAPACITY OF BETA-SITOSTEROL IN RODENT ASSAYS

BACKGROUND

Beta-sitosterol (BS) is a compound discovered to be present in numerous plants. A number of interesting biomedical properties have been attributed to BS, including immuno-modulating and anti-inflammatory activities. Therefore, the aim of this report was to evaluate its anti-inflammatory capacity by applying various rodent experimental tests.

METHODS

To carry out the objective of the study we applied the methods indicated here. Two of the adopted methods were based on the passive reverse Arthus reaction: the rat paw edema test and the rat pleurisy assay. We also applied two methods related with the non-specific acute inflammation: the mouse ear edema test, and the mouse mieloperoxidase activity assay.

RESULTS

The results obtained in all tests established a significant anti-inflammatory potential of BS. In the rat paw edema test we found an inhibitory effect which goes from 50-70%; in the rat pleurisy assay our findings with respect to the volume of pleural exuded showed a reduction of 46%, as well as a 20% low amount of neutrophils in comparison with the level of the control group. In the mouse ear edema test we found a mean inflammatory inhibition of 75%, and with respect to mieloproxidase activity the results showed a significant inhibition induced by the three doses of BS.

CONCLUSIONS

In the present study we determined a potent anti-inflammatory capacity of BS in specific and non-specific types of acute inflammation in rodents.

Theoretical basis for the activity of thalidomide

The revival of thalidomide began shortly after the drug was withdrawn from the market because of its teratogenic properties. Therapeutic effects of thalidomide were found accidentally in leprosy patients with erythema nodosum leprosum (ENL). Subsequent research widened the understanding of the activity of thalidomide, and with improved methodology and the augmented background knowledge of immunology it was possible to interpret the properties of thalidomide more coherently. Effects on tumour necrosis factor-alpha (TNFalpha) release play an important role in the ability of thalidomide to affect the immune system. Alteration of synthesis and release of cytokines such as interleukin (IL)-1, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12 and interferon-gamma is involved in the complex mechanisms of thalidomide. Thalidomide targets leucocytes, endothelial cells and keratinocytes, affecting them in a different manner and at different cellular levels. Changes in the density of adhesion molecules alter leucocyte extravasation and the inflammatory response in the tissue involved. Several mechanisms for the teratogenic action of thalidomide are currently under review, but this mode of action of the drug still remains unclear and we review evidence-based hypotheses for the teratogenicity of thalidomide. Thalidomide shows significant clinical impact in several diseases such as ENL in lepromatous leprosy, chronic graft-versus-host disease, systemic lupus erythematosus, sarcoidosis, aphthous lesions in HIV infection, wasting syndrome in chronic illness, inflammatory bowel disease, multiple myeloma and some solid tumours. In 1998 the US Food and Drug Administration approved thalidomide exclusively for the treatment of ENL, and strict conditions were stipulated for its use in order to prevent teratogenic adverse effects. However, despite the promising findings of thalidomide at the molecular level, namely its anti-TNFalpha properties and its intercalation with DNA, and activity in clinical trials, there is still a great need for more intensive research.

The Arthus reaction in rodents: species-specific requirement of complement

We induced reverse passive Arthus (RPA) reactions in the skin of rodents and found that the contribution of complement to immune complex-mediated inflammation is species specific. Complement was found to be necessary in rats and guinea pigs but not in C57BL/6J mice. In rats, within 4 h after initiation of an RPA reaction, serum alternative pathway hemolytic titers decreased significantly below basal levels, whereas classical pathway titers were unchanged. Thus the dermal reaction proceeds coincident with systemic activation of complement. The serine protease inhibitor BCX 1470, which blocks the esterolytic and hemolytic activities of the complement enzymes Cls and factor D in vitro, also blocked development of RPA-induced edema in the rat. These data support the proposal that complement-mediated processes are of major importance in the Arthus reaction in rats and guinea pigs, and suggest that BCX 1470 will be useful as an anti-inflammatory agent in diseases where complement activation is known to be detrimental.

Recombinant soluble human Fc gamma RII: production, characterization, and inhibition of the Arthus reaction

A recombinant soluble form of human Fc gamma RII (rsFc gamma RII) was genetically engineered by the insertion of a termination codon 5' of sequences encoding the transmembrane domain of a human Fc gamma RII cDNA. Chinese hamster ovary cells were transfected with the modified cDNA and the secreted rsFc gamma RII purified from the tissue culture supernatant (to > 95%, assessed by SDS-PAGE) using heat aggregated human immunoglobulin G (IgG) immunoaffinity chromatography. The IgG-purified rsFc gamma RII was relatively homogeneous (approximately 31,000 M(r)) whereas the total unpurified rsFc gamma RII secreted into the tissue culture supernatant was heterogeneous relating to N-linked glycosylation differences. Functional in vitro activity of the rsFc gamma RII was demonstrated by: (a) ability to bind via the Fc portion of human IgG and mouse IgG (IgG2a > IgG1 > > IgG2b); (b) complete inhibition of binding of erythrocytes sensitized with rabbit IgG to membrane-bound Fc gamma RII on K562 cells; and (c) inhibition of the anti-Leu4-induced T cell proliferation assay. Blood clearance and biodistribution studies show the rsFc gamma RII was excreted predominantly through the kidney in a biphasic manner, with an alpha-phase (t1/2 approximately 25 min) and a beta-phase (t1/2 approximately 4.6 h); the kidneys were the only organs noted with tissue-specific accumulation. In vivo, the administration of rsFc gamma RII significantly inhibited the immune complex-mediated inflammatory response induced by the reversed passive Arthus reaction model in rats. There was a specific and dose-dependent relationship between the amount of rsFc gamma RII administered, and the reduction in the size and severity of the macroscopic inflammatory lesion. Histological analysis of the skin showed a diffuse neutrophil infiltrate in both control and rsFc gamma RII-treated rats, however the perivascular infiltrate and the red cell extravasation was less intense in the rsFc gamma RII-treated group. It is likely that complement activation leads to neutrophil chemotaxis, but neutrophil activation via Fc gamma RII, which results in inflammatory mediator release, is inhibited. The data indicate that rsFc gamma RII is a potential therapeutic agent for the treatment of antibody or immune complex-mediated tissue damage.

Role of oxygen radicals and arachidonic acid metabolites in the reverse passive Arthus reaction and carrageenin paw oedema in the rat

1. The role of arachidonic acid metabolites and oxygen radicals in carrageenin-induced rat paw oedema and dermal reverse passive Arthus reaction (RPA) have been investigated. 2. Indomethacin (10 mg kg-1, p.o.) inhibited carrageenin paw oedema when administered 30 min before, but not 2 h after carrageenin. BWB70C (10 mg kg-1, p.o.), a selective inhibitor of 5-lipoxygenase, had no effect whether administered before or after carrageenin. Administration of both indomethacin and BWB70C had no greater anti-inflammatory effect than indomethacin alone. 3. BW755C (20 mg kg-1, p.o.), which inhibits the cyclo-oxygenase and lipoxygenase pathways of arachidonic acid metabolism, or superoxide dismutase-polyethylene glycol conjugate (SOD-PEG, 3000 u, i.v.) inhibited carrageenin paw oedema whether administered either 30 min before, or 2 h after carrageenin. 4. Pretreatment with dexamethasone (0.1 mg kg-1) or colchicine (2 mg kg-1), likewise suppressed carrageenin paw oedema. 5. BW755C (25-100 mg kg-1, p.o.) dose-dependently reduced plasma leakage in the RPA, whereas indomethacin (5 mg kg-1, p.o.) or BWB70C either alone or in combination, did not. 6. SOD-PEG (300-3000 u, i.v.) dose-dependently inhibited plasma leakage in the RPA. In addition, the iron chelator and peroxyl radical scavenger, desferrioxamine (200 mg kg-1, s.c.) also inhibited plasma leakage. 7. Pretreatment with dexamethasone (0.1 mg kg-1) or colchicine (1 mg kg-1) reduced the plasma leakage in RPA, whereas MK-886 (10 mg kg-1) had no effect. 8. These results indicate an important role for oxygen radicals but not arachidonic acid metabolites in the maintenance of carrageenin paw oedema and the plasma leakage in RPA. Furthermore, the results suggest that the anti-inflammatory actions of BW755C can be dissociated from its effects on arachidonic acid metabolism and are attributed to its anti-oxidant activity.

Suppression of the Arthus reaction by Y-24180, a potent and specific antagonist of platelet-activating factor

A novel and potent antagonist of platelet-activating factor (PAF), Y-24180 (4-(2-chlorophenyl)-2-[2-(4-isobutylphenyl)ethyl]-6,9-dimethyl-6H- thieno[3,2-f][1,2,4]triazolo[4,3-a][1,4] diazepine) was investigated for the effects on the skin reactions induced by chemical mediators and the Arthus reactions. In the rat dorsal skin, Y-24180 (0.1-10 mg/kg, p.o.) inhibited increase in vascular permeability by the intradermal PAF injection in a dose dependent manner and the inhibitory activity was 60 times more potent than that of WEB 2086. While even at doses as large as 10 mg/kg, p.o., it had no effect on vascular permeability in the rat skin induced by histamine, serotonin, bradykinin and leukotriene D4. On a reversed passive Arthus reaction in rat dorsal skin, Y-24180 (0.1-1 mg/kg, p.o.) markedly inhibited vascular permeability in a dose dependent manner and the inhibitory activity was 15 times more potent than that of WEB 2086. Y-24180 also inhibited the Arthus dermal reaction in rabbits (0.03-0.3 mg/kg, p.o.) and guinea pigs (0.1-1 mg/kg, p.o.). In addition, Y-24180 (0.1-10 mg/kg, p.o.) significantly reduced the exudate volume and the number of infiltrated inflammatory cells in the reversed passive Arthus pleural reaction in rats. Furthermore, in rat passive Arthus pancreatitis, Y-24180 (0.3-10 mg/kg, p.o.) significantly inhibited the dye extravasation from the pancreas. These results provide strong evidence that endogenous PAF plays an important role as a mediator in the type III allergic inflammation.

Antiinflammatory, analgesic, and antipyretic activities of methyl 7-butyl-4,5,6,7-tetrahydro-3-methylamino-4,6-dioxo-5-propyl-2H-pyrazol o[3, 4-d]pyrimidine-2-carboxylate (AA-2379), a novel non-acidic agent

The antiinflammatory, analgesic, and antipyretic activities of methyl 7-butyl-4,5,6,7-tetrahydro-3-methylamino-4,6-dioxo-5-propyl-2H-pyrazolo[ 3, 4-d]pyrimidine-2-carboxylate (AA-2379), a novel non-acidic agent, were examined. 1. AA-2379 had a potent antiinflammatory activity; 3-25 mg/kg, p.o. of the compound inhibited rat carrageenin-, bradykinin-, trypsin-, formalin-, dextran-, and nystatin-induced paw edema; mouse traumatic edema; and rat croton oil pouch inflammation by about 30%. The compound at 25-50 mg/kg, p.o. also inhibited the vascular permeability induced by histamine, serotonin, and bradykinin. 2. AA-2379 had an analgesic activity; the ID50 values in mouse phenylquinone-induced writhing were 10.1 mg/kg, p.o. and the compound at 12.5 mg/kg, p.o. inhibited dog urate arthritis. 3. AA-2379 at 3-10 mg/kg, p.o. showed antipyretic activity in febrile rats and rabbits. 4. AA-2379, at 500 mg/kg, p.o. was not ulcerogenic in rats. 5. These data show that AA-2379 is more active than non-acidic antiinflammatory agents, such as tiaramide and aminopyrine.

Models for evaluating the anti-inflammatory effects of inhibitors of arachidonic acid metabolism

Inhibitors of arachidonic acid metabolism were characterized by their ability to modulate slow reacting substance (SRS) and prostaglandin E2 (PGE2) release from stimulated mouse peritoneal macrophages in-vitro. Differential effects of cyclo-oxygenase (CO) and lipoxygenase (LO) enzyme inhibitors and compounds which inhibit both enzymes were demonstrated using several animal models of inflammation. Carrageenan-impregnated sponges implanted subcutaneously in rats and immune-complexes injected intraperitoneally in mice produced inflammatory responses characterized respectively by polymorphonuclear (PMN) cell infiltration and by increased vascular permeability. Dual CO/LO inhibitors (eg. BW 755c and timegadine) were capable of suppressing both parameters and reduced SRS and PGE2 formation in-vivo. In contrast, selective CO inhibitors (e.g. indomethacin, naproxen and R-830) were less active against permeability, and potentiated SRS release. Although selective CO inhibitors reduced PMN migration, this occurred at doses which exceeded those required for inhibition of PGE2. Compounds possessing LO inhibitory activity suppressed the cellular component of an Arthus type reaction in the rat pleural cavity, but were less active than selective CO inhibitors against carrageenan-induced paw oedema in rats.

Comparison of anti-inflammatory compounds in the carrageenan induced paw edema model and the reversed passive Arthus model utilizing the same animal

In order to better define antiinflammatory activity in new agents, a test was devised utilizing both carrageenan induced paw edema and the reversed passive Arthus reaction in the same animal. The model of carrageenan induced rat paw edema is a standard laboratory assay used to predict classical "aspirin-like" antiinflammatory molecules. The reversed passive cutaneous Arthus reaction involves precipitating antigen-antibody complexes, complement and infiltrating polymorphonuclear leukocytes (PMN's) and can be used to identify agents that affect one or more of these factors specifically. Antiinflammatory compounds were given orally one hour prior to the administration of carrageenan and goat anti-rat serum. Comparisons were made between several non-steroidal compounds and the steroid hydrocortisone. All of the compounds tested gave good carrageenan activity, but only hydrocortisone produced significant Arthus lesion inhibition in this assay.

Differential effects of pharmacologic agents on the reverse passive Arthus reaction in guinea pigs

Five different pharmacologic agents were examined for their effects upon edema, hemorrhage, and vascular infiltration by neutrophils in the reverse passive Arthus reaction (RPAR) in guinea pigs. Two agents, colchicine (3.0 mg/kg p.o.) and ibuprofen (100 mg/kg p.o.) significantly inhibited all three parameters of RPAR. Cobra venom factor (100 units/kg i.p.) inhibited edema and hemorrhage but it did not inhibit neutrophil infiltration. Aminophylline and sulfinpyrazone (100 mg/kg p.o.) inhibited only hemorrhage; they did not inhibit edema or neutrophil infiltration. The results from these studies with five chemically or biologically unrelated pharmacologic agents suggest that the RPAR in guinea pigs can be separated into its basic components (edema, hemorrhage, and neutrophilic infiltration) by selective inhibitors. Inhibition of edema and hemorrhage, or hemorrhage alone of the two-hour RPAR in guinea pigs is not dependent upon inhibition of neutrophilic infiltration.

Immune complexes and inflammation. A study of the activity of anti-inflammatory drugs in the reverse passive arthus reaction in the rat

The reverse passive Arthus reaction in rat skin was quantitated by using increase in wet weight as a measure of edema and extractable myeloperoxidase as a measure of the intensity of polymorphonuclear leukocyte (PMN) infiltration. Treatment of the animal with dexamethasone prior to challenge with antigen/antibody resulted in an inhibition of both edema and the infiltration of inflammatory cells. In contrast, the non-steroidal anti-inflammatory drugs inhibited the intensity of cell infiltration (PMNs but not mononuclear cells) without affecting edema. The results are discussed in the light of the effects of these drugs on arachidonic acid oxidation.

Effects of various substances on two types of inflammatory reaction in animals

The effects of 16 substances, including non-steroidal anti-inflammatory agents, a corticoid, phenols, immunomodulators and gold salts, were studied using two types of acute inflammatory reaction, a non-specific reaction (carrageenan-induced oedema) and an immune reaction (reversed passive Arthus reaction in the rat or active Arthus reaction in the mouse). Results revealed that the active Arthus model appears to be more selective than the passive reversed Arthus model, which is itself less sensitive than the carrageenan model. The active Arthus reaction might be useful for secondary screening of molecules that act on mechanisms modulating the intervention of complement and the various functions of polymorphonuclear leucocytes, and the passive Arthus reaction appears to be more suitable for preliminary screening. The activities of the different substances studied are discussed in terms of their modes of action and toxicity.

A model of Arthus pleurisy: modulation by various pharmacologic and therapeutic agents

A reversed passive Arthus reaction was elicited in the rat pleural cavity. The kinetics of this inflammatory response indicate that exudate volume (cells and fluid) reaches a maximum level approximately 2 to 4 hr postantibody challenge. The neutrophil is the major cellular constituent of the pleural exudate during the first 12 hr of this reaction, reaching peak values at 4 hr; whereas, the monocyte predominates between 15 and 24 hr. Lymphocytes, eosinophils, and mast cells were also identified in the pleural exudates. The serotonin antagonists, cyproheptadine and methylsergide, and the antihistamine, chlorpheniramine, demonstrated marginal activity in the Arthus pleurisy model. The histamine antagonist, metiamide, was inactive. The nonsteroidal anti-inflammatory agents, flurbiprofen, ibuprofen, indomethacin, and benoxaprofen caused a modest suppression of exudate volume (18-32%) and cell accumulation (28-34%). The fluid and cellular components of the Arthus reaction were significantly inhibited by dexamethasone, triamcinolone, paramethasone, and prednisolone. The oral gold preparation, auranofin, had a pronounced effect on exudate volume; whereas, other antirheumatic agents such as D-penicillamine, azathioprine, and chloroquine had no effect on the Arthus pleurisy reaction. The immunomodulator, levamisole, suppressed exudate volume, but had no effect on cell accumulation in the pleural cavity.

2,6-Di-tert-butyl-4-(2'-thenoyl)phenol(R-830): a novel nonsteroidal anti-inflammatory agent with antioxidant properties

R-830, a di-tert-butylphenol, has been shown to be anti-inflammatory in a number of animal models. These include conventional systems such as carrageenan-induced edema and adjuvant arthritis of the rat and ultraviolet-induced erythema in the guinea pig in which the acidic nonsteroidal anti-inflammatory drugs (e.g., indomethacin) are effective. The anti-inflammatory activity of R-830 has also been demonstrated in other models (e.g., graft vs. host reaction and reversed passive cutaneous Arthus reaction in the rat, contact sensitivity in the mouse) in which the acidic nonsteroidal drugs are not effective. In vitro, R-830 inhibits guinea pig lung lipoxygenase and bovine seminal vesicle cyclo-oxygenase. The antioxidant properties of R-830 were demonstrated in two in vitro systems. We speculate that the antioxidant activity of this molecule might be related to its unusual profile of pharmacological activity.

Prostaglandins. Their potential in clinical medicine

The physiologic role of the prostaglandins is complex and not yet defined precisely. Nevertheless, these ubiquitous compounds do appear important to regulation of cell function and host defenses. The therapeutic potential of the prostaglandins seems to be immense, and their use in a wide variety of clinical conditions is just beginning. Whether they will also prove helpful clinically as modulators of the immune response is not clear. It is likely that an appropriate balance of prostaglandin endoperoxides, thromboxanes, prostacyclins, and probably the stable prostaglandins themselves is important to physiologic regulation of many organ systems and of immunologic reactions. Thus, development of drugs that selectively inhibit one or another of the prostaglandins and their allied compounds may prove fruitful in treatment of many diseases, including those associated with disordered immunity and tissue injury. Prostaglandin therapy in such diseases must proceed with caution. In recent studies addition of amantadine to prostaglandin E (PGE) treatment of NZB/W mice not only increased survival of these animals, but prevented development of circulating antibodies to nuclear constituents including native DNA. The results are encouraging, but must be balanced against the observation that deprivation of prostaglandin precursors also prevented nephritis and markedly increased surival of lupus mice. However, prostaglandins might be useful in a disorder whose course is more easily monitored than that of systemic lupus erythematosus: cutaneous vasculitis. The studies in which even oral administration of a PGE1 derivative suppressed immune complex-induced vasculitis (reversed passive Arthus reaction in rat skin) suggest that a trial of PGE1 treatment of cutaneous vasculitis would not be unreasonable.