A comparison of air pouch, sponge and pleurisy models of acute carrageenan inflammation in the rat

A comparative assessment of the time course of changes in three models of acute carrageenan-induced inflammation, the six-day air pouch, polyester sponge and pleurisy models, was obtained by measuring exudate volume, leucocyte numbers, PGE2 concentrations and lactate dehydrogenase activity at 2, 6 and 24 h. The greatest increases in exudate volume, leucocyte numbers and PGE2 concentration and the smallest rise in protein occurred in the air pouch model. Increases in lactate dehydrogenase were greatest in the sponge and least in the pleural exudate, indicating that the least cell damage occurred in the pleurisy model. PGE2 was not detectable in most pleural exudate samples. The actions of two steroids, betamethasone and dexamethasome, at two dose levels, 80 and 160 micrograms/kg, were assessed in each model. Overall, the six-day air pouch was found to be most satisfactory and most sensitive for assessing the actions of the steroids. The sponge model was either less sensitive or gave inconsistent responses, for the variables measured, than the cavity models of inflammation. Since the six-day air pouch has previously been shown to resemble synovium, our findings indicate that it is likely to be superior to the other two models as a model of joint inflammation.     

The serum amyloid P response in the mouse air pouch

Abstract— Levels of the acute phase reactant serum amyloid P (SAP) have been measured in the mouse pouch model of rheumatoid arthritis. Implantation of cartilage resulted in a significant and rapid elevation in the SAP concentration, which remained high for the duration of the experiment (14 days). Initial studies with several clinically employed antirheumatic drugs indicated that dexamethasone and cyclosporin A had a marked inhibitory effect.     

乙型肝炎病毒感染不同免疫状态证候的研究思路

<正>乙型肝炎病毒(hepatitis B virus,HBV)感染是严重威胁人类健康的重要疾病之一,不仅可引起急、慢性乙型肝炎,而且与肝硬化和肝癌的发生关系密切。国内外大多数学者认为HBV本身并无致病原性,慢性乙型肝炎(CHB)属于一种明显的免疫系统疾病。     

Studies of eicosanoid production in the air pouch model of synovial inflammation

The time course of the inflammatory reaction in the rat air pouch model of synovial inflammation has been investigated at different stages of development of the lining structure using immune (pertussis vaccine) and non-immune (carrageenan) irritants. Exudate volumes and leucocyte numbers were greater with carrageenan than with pertussis vaccine but with both irritants much greater reactions were obtained when the irritant was injected at a time when the air pouch architecture most closely resembled synovium (i.e. 6 days). The time course of fluid accumulation following carrageenan in 6 day pouches was not interrupted when exudate was aspirated from the pouch six days after carrageenan injection. In the 6 day old air pouch PGE2 and 6-oxo-PGF1 alpha concentration peaked at 6 hours and 24 hours respectively. With carrageenan and pertussis vaccine stimulation, LTB4 concentrations were maximal at 3-6 hours with both irritants and low concentrations were still present at 13 days. The presence of a lining structure was found to influence concentrations of PGE2 in the air pouch. Pre-treatment with colchicine or 5-fluorouracil to reduce cell accumulation was not found to effect the modified PGE2 response. Our findings suggest that the presence of a synovial like lining structure may induce changes in composition in respect to cellular content and in putative mediator concentrations. We conclude that it is important in elucidating the mechanisms involved in arthritic inflammation to study injury in a cavity lined by macrophages and fibroblasts.     

The effect of desferrioxamine on antigen-induced inflammation in the rat air pouch

The effect of desferrioxamine, a relatively specific iron chelating drug, has been examined in an allergic air pouch model of inflammation in the rat. The model has both an acute and chronic phase and allows quantitative measurements of the cellular and exudative response within the pouch fluid and the tissue response in the membrane that develops around the preformed cavity. Desferrioxamine given as a single bolus injection, directly into the cavity, stimulated the acute inflammatory phase, increasing both the exudative and leukocyte response, in a dose-dependent fashion. In marked contrast, repeated injections during the acute to chronic phase or during the established chronic reaction, led to a reduction in both leukocyte numbers within the cavity and the amount of granulation tissue surrounding it. The exudative response was, however, unaltered. These results are discussed in relation to the potential role of iron in promoting an acute and chronic inflammatory reaction.     

Granulomatous tissue formation of shikon and shikonin by air pouch method.

"The extract of shikon" (SK) and shikonin play important roles in the development of granulomatous tissue formation. To reveal the augmenting effect of SK or shikonin on vascular endothelial growth factor (VEGF) production and neovascularization, we investigated murine granulomatous tissue induced by SK and shikonin, comparing them to pouches in which trehalose 6,6'-dimycolate (TDM) was injected. The development of granulomatous tissue formation was evaluated by the wet weight of pouch walls. At day 5 and 7 after SK and shikonin injection, prominent granulomatous tissue formation was detected. Histological observations on the development of granulomatous tissue showed that the pouch was formed in the submuscular connective tissue and necrotic tissue directly facing the cavity and granulomatous tissue developed in the connective tissue. At day 1, VEGF-positive neutrophils accumulated in the pouch wall. Granulomatous tissue formation and neovascularization by injection of SK or shikonin was not more prominent than TDM. However, the present results indicate that SK and shikonin induce neovascularization in granulomatous tissue.     

Modulatory effect of fosfomycin on acute inflammation in the rat air pouch model

We examined the effect of fosfomycin (FOM) on the inflammatory response induced by carrageenan in the rat. Air pouches were induced subcutaneously on the backs of rats and injected with carrageenan. The rats were treated with either vehicle or FOM at a dose of 100 mg/kg 1 h before carrageenan challenge. After carrageenan challenge (48 h), the air pouches were removed and analyzed. The volume, protein amounts and cell counts in the exudate obtained from FOM-treated animals were significantly reduced compared with that from vehicle-treated animals. The contents of PGE(2) and TNF-alpha, and mRNA for cyclooxygenase-2 were also markedly suppressed in FOM-treated rats. Histological examination showed suppression of the inflammatory response in the pouch tissues from FOM-treated rats.     

Synthesis of polypeptide models of collagen

It is well known that the amino acid sequence of collagen contains a large number of tripeptide units such as Y-X-Gly, where Y and X can be any amino acid residue but most frequently are proline or hydroxyproline. Accordingly, several sequential polytripeptides, including repeating sequences of that type containing one or two imino acid residues, have been synthesized and studied in solution and/or in the solid state (1–14). In this paper we describe in detail the syntheses via active esters of four polytripeptides of the type poly(Pro-X-Gly) and poly(X-Pro-Gly), where X is isoleucine or norleucine. The general objective was to study the influence of hydrophobic residues on the stability of collagen three-dimensional structure; in particular we were interested in the introduction of branching at C^β in view of the recent calculations of Némethy & Scheraga (15). The Nle residue was introduced in order to obtain reference polymers without any branching in the side chain. By way of comparison, we have shown earlier that polymeric sequences where X is leucine (branching at the C^γ) possess collagen-like structures in an appropriate milieu (10, 11). The results of both theoretical and experimental conformational studies on the polymers will be published in a forthcoming paper. Syntheses via p-nitrophenyl esters are described for poly(Pro-Ile-Gly), poly(Ile-Pro-Gly), poly(Pro-Nle-Gly) and poly(Nle-Pro-Gly), four synthetic polytripeptide analogues of the non-polar regions of collagens. The obtained polymers exhibit molecular weights in the range 5000–10000 as judged from viscosity measurements.     

A rat air pouch model for evaluating the efficacy and selectivity of 5-lipoxygenase inhibitors

The 5-lipoxygenase (5-LOX) pathway has been associated with a variety of inflammatory diseases including asthma, atherosclerosis, rheumatoid arthritis, pain, cancer and liver fibrosis. Several classes of 5-LOX inhibitors have been identified, but only one drug, zileuton, a redox inhibitor of 5-LOX, has been approved for clinical use. To better evaluate the efficacy of 5-LOX inhibitors for pharmacological intervention, a rat model was modified to test the in vivo efficacy of 5-LOX inhibitors. Inflammation was produced by adding carrageenan into a newly formed air pouch and prostaglandins produced. While macrophages and neutrophils are present in the inflamed pouch, little 5-LOX products are formed. Cellular 5-LOX activation was obtained by adding calcium ionophore (A23187) into the pouch thus providing a novel model to evaluate the efficacy and selectivity of 5-LOX inhibitors. Also, we described modifications to the in vitro 5-LOX enzyme and cell assays. These assays included a newly developed fluorescence-based enzyme assay, a 5-LOX redox assay, an ex vivo human whole blood assay and an IgE-stimulated rat mast cell assay, all designed for maximal production of leukotrienes. Zileuton and CJ-13,610, a competitive, non-redox inhibitor of 5-LOX, were evaluated for their pharmacological properties using these assays. Although both compounds achieved dose-dependent inhibition of 5-LOX enzyme activity, CJ-13,610 was 3-4 fold more potent than zileuton in all-assays. Evaluation of 5-LOX metabolites-by LC/MS/MS and ELISA confirmed that both compounds selectively inhibited all products downstream of 5-hydroperoxy eicosatetraenoic acid (5-HPETE), including 5-oxo-6,8,11,14-eicosatetraenoic acid (5-oxoETE), without inhibition of 12-lipoxygenase (12-LOX), 15-lipoxygenase (15-LOX), or cyclooxygenase (COX) products. In the rat air pouch model, oral dosing of CJ-13,610 and zileuton resulted in selective inhibition 5-LOX activity from pouch exudate and ex vivo rat whole blood with similar potency to in vitro assay. These data show that the rat air pouch model is a reliable and useful tool for evaluating in vivo efficacy of 5-LOX inhibitors and may aid in the development of the next generation of 5-LOX inhibitors, such as the non-redox inhibitors similar to CJ-13,610.     

The subcutaneous air pouch model of synovium and the inflammatory response to heat aggregated gammaglobulin

Subcutaneous injection of sterile air in rodents results in the formation of an air pouch with a lining morphologically similar to synovium (Edwards et al., 1981). We extended the comparison between pouch and synovial tissue and confirmed broad similarities in structure and function but also noted important differences. The air pouch was used to study the time course of the acute inflammatory response to heat aggregated human IgG. Saline washout of the pouch allowed simultaneous measurement of cellular and mediator components of the inflammatory exudate. The aggregates were rapidly phagocytosed by the pouch lining cells, resulting in acute inflammation characterised by polymorphonuclear leucocyte infiltration with peak numbers in the exudate at 12 hours, temporally dissociated from the earlier peak of PGE2 at 3 hours.     

Humoral and cellular immunologic aspects of adjuvant and collagen arthritis in rats

Systemic and local immunological responses of rats sensitized with either M. butyricum or native type II collagen have been evaluated. In rats exhibiting adjuvant-induced arthritis no antibodies to collagen could be detected. In animals exhibiting collagen-induced arthritis, high antibody titers developed by day 14, and could be correlated with the severity of the arthritis. Delayed type hypersensitivity (DTH) responses were measured by a 5-iodo-2'-deoxyuridine 125-I (125-IUdR) uptake assay. Arthritic scores in rats immunized with collagen were not accompanied by a positive DTH response, whereas adjuvant arthritic rats showed a positive response. T-lymphocyte cellular responses in both adjuvant- and collagen-induced arthritic rats were measured. In neither syndrome were major alterations observed in T-lymphocyte subpopulations. These results provide evidence that adjuvant-induced arthritis and type II collagen-induced arthritis are distinct entities, and that they may be discriminated by the nature of the humoral response.     

Changes in histamine and prostaglandins in acute inflammatory air pouch in mice

The changes in histamine and prostaglandins (PGE2 and PGF) in carrageenan-induced acute inflammation were studied in 6 day old air pouches in mice. A significant elevation of exudate histamine was found 1 hour after the carrageenan injection. Highest vascular permeability at the site of inflammation was also found at 1 hour. Both PGE2 and PGF showed steady increases in the pouch exudate and reached significantly higher levels at 24 hours. The present findings thus suggest that histamine is involved in the early phase of carrageenan-induced inflammation by enhancing vascular permeability. The increases in PGE2 and PGF appear to be closely correlated with the increased exudate cell accumulation. This leads us to suggest that they are likely to be involved in the exudate cell activity rather than in enhancing the vascular permeability which was found to decrease at 4 hours after the carrageenan injection.     

Pharmacological investigation of acute cellular accumulation in immunological air pouch inflammation

Immunologically-mediated cellular accumulation was measured 24 hours after antigenic challenge using a rat subcutaneous air pouch model. This response was inhibited by treatment with prednisolone, colchicine, anti-thymocyte serum and systemic antigen. In contrast, administration of a range of other pharmacological and clinically active agents had little effect. The profile of inhibitory activity suggested that this response was mainly due to delayed type hypersensitivity with little anaphylactic or Arthus-type component.     

Modulatory effect of mycophenolate mofetil on carrageenan-induced inflammation in the mouse air pouch model

The treatment of some inflammatory diseases, such as rheumatoid arthritis, remains an important target for studies because some patients are refractory to conventional treatment. Mycophenolate mofetil (MMF), an immunosuppressive drug, has been shown to have a beneficial effect on the therapy of inflammatory and autoimmune diseases. In the present study, we aimed to analyse the anti-inflammatory effect of MMF administered by oral route in the mouse carrageenan-induced air pouch model. Results: MMF significantly inhibited the influx of leukocytes, exudate concentrations (P<0.01), activities of myeloperoxidase (MPO) and adenosine deaminase (ADA), levels of nitrite/nitrate (NO(x)) and inducible nitric oxide synthase (iNOS) mRNA expression, as well as the levels of mRNA expression and proteins of tumor necrosis factor-alpha (TNF-α), Interleukin-beta (IL-1β) and vascular endothelial growth factor-alpha (VEGF-α) (P<0.05). These results provide evidence that MMF has an important anti-inflammatory effect in reducing the influx of leukocytes and exudate concentrations. These inhibitory effects are correlated with the inhibition of specific pro-inflammatory enzymes (MPO, ADA and iNOS), and the levels of mRNA expression and proteins of TNF-α, IL-1β and VEGF-α.     

Novel vaccines and adjuvant systems: the utility of animal models for predicting immunogenicity in humans

Animal models are essential for acquiring safety, immunogenicity and efficacy data to support the development of novel vaccines. However, extrapolating such results to designing human trials is challenging due to species-specific differences in responses to antigens, adjuvants and pathogens. As well, most early vaccine work is conducted with in-bred mouse strains which may fail to uncover issues that could arise later in out-bred populations. Unlike drugs designed to be delivered systemically, vaccines work within a somewhat localized space, so allometric dose scaling to account for body size differences is not necessarily relevant. Comparison of immune responses and correlates of protection with a given antigen show widely variable results between animals and humans, even where protective immunity against challenge with the same pathogen can be studied. For adjuvants, it is possible to compare enhancement of immunogenicity compared to a non-adjuvant control vaccine. While some novel adjuvants provide similar levels of enhancement between species, others do not. It is also important to recognize the inter-relationship between antigens and adjuvants, since one can compensate for the other, masking particular effects. Despite all the limitations, animal immunogenicity and efficacy studies form an important part of pre-clinical development for novel vaccines, but considerable prudence is required when using and extrapolating results.     

The anti-inflammatory modulatory role of Solidago chilensis Meyen in the murine model of the air pouch

The aim of this study was to investigate the anti-inflammatory efficacy of an aqueous extract (AE), and its butanolic (BuOH) and aqueous residual (AR) fractions, derived from the rhizome of Solidago chilensis in inflammation caused by carrageenan in mice. Solidago chilensis Meyen rhizome was extracted using hot water at 90 degrees C under infusion. The extract was filtered and lyophilized. Part of the aqueous extract was fractionated with n-BuOH, resulting in butanolic (BuOH) and aqueous residual (AR) fractions. Adult Swiss mice were used in the in-vivo experiments. We evaluated the effect of rhizome aqueous extract of Solidago chilensis and these two derived fractions on the inflammation induced by carrageenan in the mouse model of the air pouch. The aqueous extract and its derived fractions significantly inhibited leucocytes, neutrophils, exudation, myeloperoxidase and adenosine deaminase activity, as well as nitric oxide, interleukin-1 beta (IL-1beta), neutrophil chemokine (KC) and tumour necrosis factor-alpha (TNF-alpha) levels (P < 0.05). Indometacin and dexamethasone inhibited all the studied inflammatory parameters (P < 0.01) with the exceptions that indometacin did not inhibit TNF-alpha levels and dexamethasone did not inhibit KC levels (P > 0.05). These results indicate that Solidago chilensis has a significant anti-inflammatory action on acute inflammatory responses and that its inhibitory activity may be due not only to the inhibition of proinflammatory mediators, but also to the inhibition of leucocyte infiltration.