Pharmacologic evaluation of A23187-induced contractions of three distinct preparations of guinea pig lung parenchymal strips

The present investigation examined the pharmacologic profiles of three distinct guinea pig lung parenchymal strips (LPS): intact LPS, denuded LPS (devoid of any lung pleura) and pleural surface strips. All three preparations responded similarly to increasing concentrations of KCl, whereas maximum contractile responses of the intact LPS and pleural surface strips to histamine, LTD4 and U46619, a thromboxane A2 mimetic, were significantly greater (P less than 0.001) than those elicited by the denuded LPS. Moreover, concentration-response curves for intact LPS and pleural surface strips to ovalbumin and ionophore A23187 challenges were equivalent to each other, which were significantly (P less than 0.001) higher in magnitude than that for the denuded LPS. The net contractile response of the denuded LPS to A23187 was significantly reduced by 35% in the presence of 1 x 10(-5) M A-64077, a 5-lipoxygenase inhibitor, and nearly abolished with the addition of 1 x 10(-6) M pyrilamine and 4 x 10(-6) M indomethacin. In contrast, the maximum contractile responses of the intact LPS and pleural surface strips were reduced by 40 and 30%, respectively, in the presence of all three inhibitors. On the other hand, morphometric analysis revealed that the density of mast cells in the smooth muscle of lung pleura was as high as that found in the bronchiolar area (2.35 +/- 0.31 vs. 2.62 +/- 0.28 per 0.05 mm2). In contrast, mast cells were scarcely identified in the alveolar parenchyma.(ABSTRACT TRUNCATED AT 250 WORDS)

Anti-inflammatory activity of BF389, a Di-T-butylphenol, in animal models of arthritis

Biofor 389 (BF389), dihydro-4-[[3,5-bis(1,1-dimethyl)-4-hydroxyphenyl] methylene]-2-methyl-2H-1,2-oxazin-3(4H)-one, was tested for anti-inflammatory activity in various animal models of arthritis. Initial evaluation in the lipoidalamine (LA) arthritis model in rats (5-day dosing protocol) resulted in an oral ED50 of 4.9 mg/kg for inhibition of paw swelling. No effects on splenomegaly were observed, suggesting that the compound was efficacious as a result of anti-inflammatory rather than immunomodulatory effects. BF389 was efficacious in interleukin 1 (IL-1)-enhanced type II collagen arthritis in rats (oral ED50 less than 1.0 mg/kg) as assessed by paw volume measurement and histologic evaluation of joints. Mice with IL-1-enhanced type II collagen arthritis given 30 mg/kg of BF 389 had significantly lower histological scores for joint damage than did untreated controls. Normal rats given single oral doses of BF389 had significant suppression of arachidonate-stimulated whole blood prostaglandin E2 and thromboxane B2 production 2 hr postdosing (ED50 = 0.1 mg/kg). Leukotriene B4 production in these animals was not decreased. After it became apparent that the compound was a potent inhibitor of prostaglandin production in vivo, a study was done to compare the efficacy and toxicity of BF389 with several currently marketed nonsteroidal anti-inflammatory drugs, piroxicam, naproxen and diclofenac. Lipoidalamine-injected rats were given daily oral doses of BF389 or the comparators for 21 days. Quantitation of effects on arthritis on day 21 resulted in ED50 values of 0.9 mg/kg (BF389), 3.9 mg/kg (naproxen), 4.9 mg/kg (diclofenac) and 0.6 mg/kg (piroxicam).(ABSTRACT TRUNCATED AT 250 WORDS)

Anti-inflammatory activity of pergolide, a dopamine receptor agonist

Pergolide, a dopamine agonist effective in the treatment of Parkinson's disease, has been shown to have anti-inflammatory activity in the carrageenan paw edema assay in rats at p.o. doses greater than or equal to 0.3 mg/kg. Studies were done to investigate the mechanism of action and to determine the pharmacologic significance of this finding. Because pergolide elevates circulating glucocorticoids, the effect of pergolide on carrageenan-induced paw swelling was assessed in adrenalectomized rats. Pergolide retained its anti-inflammatory activity in adrenalectomized carrageenan-injected rats, thus eliminating corticosterone induction as a possible mechanism of action. Pergolide treatment also did not decrease thromboxane B2, prostaglandin E2 or leukotriene B4 production, ruling out direct effects on arachnoid acid inflammatory mediators. Interactions with the autonomic nervous system were suggested, in that an alpha adrenergic agonist (clonidine) mimicked the activity of pergolide in the carrageenan assay, and an alpha adrenergic antagonist (phenoxybenzamine) blocked the anti-inflammatory activity of pergolide in this assay. Dopamine receptor antagonists (haloperidol or sulpiride) partially inhibited the effect of pergolide in the carrageenan model. However, the peripherally restricted dopamine antagonist, domperidone, was ineffective, suggesting that a central dopamine receptor was involved in the effect. Experiments in chronic inflammation models such as lipoidal-amine induced arthritis in rats and picryl chloride-induced delayed type hypersensitivity in mice also revealed an anti-inflammatory effect of pergolide. Activity in the carrageenan system and the lipoidalamine model demonstrated that the anti-inflammatory effects of pergolide were separable from potential immunosuppressive effects. Multiple dose studies indicated that tolerance might develop to the anti-inflammatory effect of pergolide.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of anti-arthritic drugs on IL-1 induced inflammation in rats

Intra-articular injection of IL-1 in rats results in profound changes in the synovial joints including edema, synovitis, cartilage degeneration and fibroblast proliferation. We have tested the efficacy of several anti-arthritic drugs in this model to characterize the mechanism of IL-1 induced inflammatory lesions. The response to IL-1 was evaluated by measurement of soft-tissue swelling and by histological scoring. Dexamethasone, and several NSAIDS were effective in reducing the soft tissue swelling but only some were effective in improving the histological lesions. The slow-acting antirheumatic D-penicillamine and immunosuppressive agents such as cyclosporine A were ineffective. These observations provide further evidence that in vivo, at least some aspects of IL-1 induced changes in rat knee joints are likely to be prostaglandin mediated.

Development of a rapid screen for detecting and differentiating immunomodulatory vs. anti-inflammatory compounds in rats

Polyarthritis can be induced in rats using a synthetic adjuvant, N,N-dioctyldecyl-N', N-bis(2-hydroxyethyl) propanediamine (LA) suspended in oil. The disease is morphologically indistinguishable from the classic adjuvant arthritis induced by Freund's complete adjuvant (FCA). LA injection (7.5 mg/animal) consistently induced paw swelling, splenomegaly and fibrinogen level increases at certain time points. Studies evaluating various protocols and parameters determined that a 15 day assay where agents administered from days 9 through 13, would differentiate immunomodulatory and anti-inflammatory compounds. Parameters utilized were body weight, paw volumes, spleen weights, and fibrinogen levels. Immunomodulatory agents reduce paw swelling, splenomegaly and in some cases fibrinogen levels. NSAIDS reduce paw swelling, increase splenomegaly and have no effect on fibrinogen levels. These results indicate that compounds active in the traditional FCA assay can be detected and differentiated with respect to anti-inflammatory vs. immunomodulatory activity in a rapid screen.

Effects of body weight restriction on the development and progression of spontaneous osteoarthritis in guinea pigs

Hartley albino guinea pigs develop spontaneous osteoarthritis (OA) of the knee joint. A study was done to determine the importance of body weight in the pathogenesis of this disease. Two groups of 20 male guinea pigs each were maintained on the same diets. The control group was allowed ad libitum feed consumption and the other group was restricted to 30-35 gm of feed per day. Ten animals from each group were killed at 9 months of age to evaluate histologic features of the knee joints. The severity of the OA lesions was reduced by 40%, in conjunction with a 28% decrease in body weight, in the diet-restricted group. The remaining animals were killed at 18 months of age. Those in the diet-restricted group had a 56% reduction in severity of lesions, with a 29% decrease in body weight. These results indicate that body mass in guinea pigs, as in humans, is an important predisposing factor for the development of spontaneous OA of the knee.

Quantitation of bronchiolar epithelial proliferation in A23187-exposed guinea pigs

Aerosol exposure to the ionophore A23187 results in PMN accumulation, airway epithelial injury and prolonged airway constriction. Bronchiolar epithelial damage in ionophore-exposed guinea pigs was quantitated by measuring epithelial proliferation using bromodeoxyuridine (BRDU). Animals were killed at 24, 48 or 72 hours post-ionophore exposure and lungs were collected for H & E and immunostaining. Numerical scores were assigned for morphologic changes and the number of labeled cells per mm of airway was determined. Significant increases in labeled epithelial cells were evident at 48 hours. Inflammation and epithelial damage scores also were elevated. These results indicate that ionophore exposure results in pulmonary inflammation and bronchiolar epithelial proliferation as assessed by BRDU labeling.

Interleukin 1 mediated acceleration of type II collagen-induced arthritis: effects of anti-inflammatory or anti-arthritic drugs

We previously demonstrated that treatments with rIL-1 beta accelerated the onset and progression of CIA in mice. In the present study, it was observed that IL-1 also enhanced the development of CIA in rats. Like the mouse model, maximal incidence (80-100%) of arthritis occurred within 7 days after the first treatment with IL-1 in rats. Thus, the acceleration of CIA by IL-1 (IL-1 CIA) may be an improved model for the rapid screening of anti-inflammatory and/or anti-arthritic drugs. As a first step to determining the utility of the IL-1 CIA model as a drug screen, we examined the ability of various known anti-inflammatory and anti-arthritic drugs to modify the IL-1 mediated enhancement of CIA in both rats and mice. The results of these studies showed that when analyzed in the IL-1 CIA model, rats and mice exhibited differences in their responses to several of these drugs. For example, dexamethasone, cyclophosphamide, azathioprine, various non-steroidal anti-inflammatory drugs (NSAIDs) as well as methotrexate were found active in the IL-1 CIA of rats. By contrast, the NSAIDs were found to be less effective in suppressing the IL-1 accelerated disease in mice. In both rats and mice, cyclosporine A and several disease modifying anti-arthritic drugs failed to the prevent the development of CIA that was potentiated by IL-1. Thus, in the IL-1 CIA model NSAIDs appeared to be less active in mice than rats. In conclusion, because of the shorter latent period required for the development of arthritis in the IL-1 treated animals, the IL-1 accelerated CIA model in both mice and rats may be useful for screening anti-inflammatory or anti-arthritic compounds.

Passive role of articular chondrocytes in the pathogenesis of acute meniscectomy-induced cartilage degeneration

The importance of viable articular chondrocytes and enzymes or factors from surgically traumatized synovium in the pathogenesis of acute meniscectomy-induced cartilage degeneration was examined in guinea pigs (nine groups of five animals each). Iodoacetate injected intra-articularly was used to kill articular chondrocytes of guinea pigs prior to meniscectomy to determine if they were active participants in the acute lesion induction. Lesions of similar severity to those occurring in animals with viable chondrocytes at the time of surgery were observed, suggesting that the chondrocytes were not actively involved in the pathogenesis in this group. In an additional group of guinea pigs in which chondrocytes were killed by iodoacetate, the medial collateral ligament was transected to determine if acute degenerative changes could be induced in acellular cartilage exposed to a surgical manipulation that does not by itself induce lesions but does expose cartilage to enzymes/factors from traumatized synovium. Transecting the medial collateral ligament and entering the joint space without induction of instability via meniscectomy did not result in histologic evidence of cartilage damage. This suggests that synovial trauma and mild inflammation were insufficient to induce matrix degeneration in the absence of abnormal load bearing. In further support of this, guinea pigs subjected to unilateral sciatic neurectomy at the time of meniscectomy were protected against development of acute cartilage degeneration. Results of this study suggest that articular cartilage devoid of viable chondrocytes at the time of meniscectomy responds acutely in much the same way as intact cartilage subjected to this procedure.

Effects of hepatic ischemia-reperfusion injury on the hepatic mixed function oxidase system in rats

Hepatic ischemia induced in vivo by ligation of the left hepatic lobe of rats for up to 2 hr had no effect on cytochrome P-450, cytochrome c reductase, or lobe histology; however, cytochrome b5 increased with ischemia duration. Ethylmorphine demethylation decreased 35% after 2 hr of ischemia. Reperfusion of tissue previously made ischemic for up to 2 hr was associated with appreciable necrosis as well as decreases in cytochrome P-450, cytochrome b5, cytochrome c reductase, and ethylmorphine demethylation. Serum alanine transaminase and aspartate transaminase concentrations were increased by reperfusion of previously ischemic tissue. Reperfusion of the previously ischemic lobe for 18 hr was associated with a greater loss of cytochromes P-450 and b5, cytochrome c reductase, and ethylmorphine demethylation than reperfusion for 1 hr. The total decrease in cytochrome P-450 and b5 content was equal to the decrease in total microsomal heme content, although cytochrome P-450 decreased more than cytochrome b5. Ethoxyresorufin deethylation by hepatic microsomes from 3-methylcholanthrene-treated rats was decreased by ischemia-reperfusion; however, pentoxyresorufin dealkylation by hepatic microsomes from phenobarbital-treated rats was not, suggesting specific cytochrome P-450 isozyme loss. In vitro NADPH-dependent lipid peroxidation in hepatic microsomes from control and phenobarbital- and 3-methylcholanthrene-treated rats resulted in a selective decrease of ethoxyresorufin but not pentoxyresorufin dealkylation, similar to that observed in livers subjected to ischemia-reperfusion in vivo. These data suggest that cytochrome P-450, ethylmorphine demethylation, and ethoxyresorufin deethylation are more susceptible to ischemia-reperfusion injury than cytochrome b5 or pentoxyresorufin dealkylation.

Effects of chronic treatment with the leukotriene D4-antagonist compound LY171883 on B6C3F1 mice

A 2-year toxicity/oncogenicity study was done to evaluate the potential effects of the leukotriene antagonist LY171883 in B6C3F1 mice. Dietary concentrations of LY171883 during the initial 7 months of the study were 0.0, 0.005, 0.015, or 0.05% but were increased to 0.0, 0.0075, 0.0225, or 0.075% during Months 7 through 24. The estimated average daily compound intake was 0.0, 7.3, 22.5, or 80.5 mg/kg for males and 0.0, 9.2, 27.5, or 95.9 mg/kg for females. Survival was not adversely affected by treatment, however, body weight of males and females in the high dose group was significantly lower than that of controls. The chronic toxicity was localized primarily to the liver. Liver weights were increased in males in the high dose group and in females in the mid and high dose groups. Microsomal p-nitroanisole-O-demethylase activity was increased in mid and high dose females. Hepatic peroxisomal beta-oxidation was increased approximately twofold in both sexes in the high dose group only. Centrilobular eosinophilic granular change of hepatocytes was a common histopathologic finding in male and female mice in the high dose group, with the incidence and severity being greater in females. An increased incidence of hepatocellular carcinomas was observed in female mice in the mid and high dose groups. The number of male mice in the high dose group with hepatocellular carcinomas was higher than that of controls but the change was not statistically significant. Hepatocellular adenomas were increased in females in the high dose group but not in males. All groups of treated females had increased nodular hepatocellular hyperplasia.(ABSTRACT TRUNCATED AT 250 WORDS)

Arthritis induced by interleukin-1 is dependent on the site and frequency of intraarticular injection

Intraarticular injection of recombinant human interleukin-1 (IL-1) in rats resulted in varying degrees of inflammatory changes depending on the site and frequency of injections. (i) Much lower amounts of IL-1 were required to elicit an inflammatory response in the ankle joints (15-3000 ng) than the knee joints (90-150 micrograms). (ii) The inflammatory response was much greater if IL-1 was administered in multiple doses as compared to a single dose injection. One day after a single injection of IL-1 (90-150 micrograms), knee joints exhibited a mild increase in volume as a consequence of edema, but at the end of 1 week, no discernible change in volume was observed. However, when the same total amount of IL-1 was injected in three doses, there was a dramatic increase in joint volume at the end of 1 week that persisted for at least 3 weeks. The increase was dose dependent. (iii) The inflammatory response was dependent on the age/weight of the rats: the older the animals the greater the response. (iv) Under conditions where IL-1 induced inflammatory changes in knee joints, recombinant tumor necrosis factor failed to induce any significant response. (v) Histological examination of the knee joints revealed distinct differences in the pathological response to the two different protocols of IL-1 administration in the knee joints. The animals injected with a single dose of IL-1 showed a mild and transient inflammation that was resolved by 2 weeks postinjection, but exhibited degenerative changes associated with focal loss of chondrocytes and proteoglycan of the knee joint cartilage, which became progressively severe. The knee joints of animals given three injections of IL-1 showed evidence of marked acute synovitis, fibroplasia, loss of proteoglycan and chondrocytes, resorption of subchondral bone, and transition of hematopoeitic marrow cells into cells of mesenchymal morphology. (vi) Examination of proteoglycan synthesis by cartilage of IL-1-injected rats revealed that within 1 day after injection, a dramatic reduction in synthesis occurred which persisted for at least 2 weeks. These studies suggest that intraarticular injection of IL-1 provides a useful rodent model for the investigation of pathological changes occurring within a localized joint as a result of acute and chronic inflammatory stimuli. Relevant aspects of the pathology of joint erosion can be demonstrated depending on the frequency of IL-1 injection.

Interleukin 1 enhances the development of spontaneous arthritis in MRL/lpr mice

We previously reported that treatments with human recombinant interleukin-1 beta (rIL-1 beta) in DBA/1 mice which were suboptimally immunized with native chick type II collagen (NcII) markedly accelerated the onset of collagen-induced arthritis (CIA). In the present study, we further characterized this IL-1-mediated enhancement of murine arthritis by examining the in vivo effects of rIL-1 beta in another arthritis model, namely, the spontaneous arthritis of the MRL/lpr mouse strain. The results of these studies demonstrated that IL-1 treatments also enhanced the onset and progression of the spontaneous arthritic disease in MRL/lpr mice. A substantial proportion of the IL-1-treated MRL/lpr mice that were between 3 and 3.5 months of age exhibited swelling in either the hind or front paws. Moreover, histopathologic studies demonstrated the presence of striking alterations within the various joints of these IL-1-treated MRL/lpr mice. Such abnormalities were not detected in the non-IL-1-treated, age-matched MRL/lpr mice. Therefore, as in the experimentally induced disease of CIA, IL-1 may also be capable of contributing to the pathogenesis of the spontaneous arthritis of MRL/lpr mice.

Passive role of articular chondrocytes in quinolone-induced arthropathy in guinea pigs

The role of articular chondrocytes and matrix degrading enzymes such as collagenase and neutral protease in the pathogenesis of quinolone-induced cartilage degeneration was investigated in immature guinea pigs. Articular cartilage from nalidixic acid (NA) treated guinea pigs was examined for the presence of protease activity or the ex vivo synthesis of collagenase at various times post-treatment. Histologic evaluation of knee joints confirmed the presence of degenerative changes in the matrix, but increased collagenase synthesis or protease activity were not detected. A separate group of animals was used to determine the importance of articular chondrocytes in the lesion generation. These cells were killed by intra-articular injection of the glycolysis inhibitor iodoacetic acid (IA) prior to treatment of the animals with NA. Typical "blister-like" their presence was not required for lesion development. Cartilage exposed to IA only did not exhibit "blister-like" lesions indicating that chondrocyte death and proteoglycan loss in conjunction with frictional forces associated with load-bearing were not sufficient to induce major matrical disruptive changes during the period of this study. These results indicate that articular chondrocytes are not actively involved in inducing the degenerative changes and provide no evidence for involvement of collagenase or neutral protease in the pathogenesis of the lesion.

Effects of chronic treatment with the leukotriene D4 antagonist compound LY171883 on Fischer 344 rats and rhesus monkeys

One-year toxicity studies were done to evaluate potential toxic effects associated with chronic exposure of rats and monkeys to the leukotriene antagonist LY171883. Rats were fed dietary doses of 0.0, 0.01, 0.03, or 0.1%, equivalent to approximately 0, 5, 15, or 50 mg/kg of body weight/day. Monkeys were given daily nasogastric gavage doses of 0, 30, 75, or 175 mg/kg of body weight. No treatment-related effects occurred in physical, behavioral, ocular, food consumption, or urinalysis parameters in either species. Mild dose-related hepatotoxicity occurred in rats given approximately 15 or 50 mg/kg of LY171883. The hepatotoxicity was characterized by liver enlargement associated with induction of hepatic peroxisomal beta-oxidation and microsomal drug metabolism. Male rats also had hepatocellular fatty change, centrilobular hypertrophy of hepatocytes, and increased levels of serum alanine transaminase and total bilirubin. Other effects in rats included minimal decreases in hematocrit values, decreases in serum triglycerides and cholesterol, and increased kidney weight. The monkeys tolerated daily oral doses of LY171883 up to 175 mg/kg with only minor increases in hepatic microsomal enzyme activity and slightly increased liver and kidney weights in males. No effects occurred in monkeys given 30 mg/kg. There was no induction of hepatic peroxisomal enzymes or pathologic abnormalities in monkeys treated with LY171883. The peroxisomal inductive effect was apparently a species-related effect separate from the pharmacologic activity of leukotriene antagonism.

Interleukin 1-induced pathophysiology: induction of cytokines, development of histopathologic changes, and immunopharmacologic intervention

In this report, we describe a murine system in which treatment with recombinant human interleukin 1 (IL-1) induced an acute lethal state with pathologic changes similar to septic shock at high doses and development of arthritic and other tissue changes following more prolonged treatment with lower doses. We have demonstrated that both recombinant human interleukin 1 alpha and recombinant human interleukin 1 beta could be administered to an endotoxin hyporesponsive strain, C3H/HeJ, and produce these pathologic changes. Induction of tumor necrosis factor (TNF) and colony-stimulating factor activity was noted. The ability to induce these changes was dose and time dependent. Histopathologic changes included lesions in the lung, heart, liver, adrenal glands, intestines, and joints. Neutrophil infiltration was a prominent feature in many organs. Drugs, immunotherapy, or other treatments which have been effective in delaying or preventing a lethal syndrome induced following high dose interleukin 2 therapy were not effective in preventing the interleukin 1-induced lethal syndrome. Interestingly, pretreatment with low nonlethal doses of IL-1 (but not lipopolysaccharides or TNF) could prevent deaths from an LD100 challenge dose of IL-1.

Regulation of serum tumor necrosis factor in glucocorticoid-sensitive and -resistant rodent endotoxin shock models

Bolus injection of lethal or sublethal doses of endotoxin or lipopolysaccharide (LPS) results in the rapid and transient rise in tumor necrosis factor (TNF) levels in serum in mammals. TNF levels peak between 1 and 2 h after LPS injection in mice and guinea pigs and approach basal levels by 6 h. Although the kinetics of TNF in serum appear similar between these two species, guinea pigs respond to a lethal dose of LPS of 20 mg/kg by producing approximately 10-fold more TNF than mice do. These two endotoxin shock models also differ in their sensitivity to glucocorticoids. TNF levels in serum are not reduced in the lethal endotoxin shock model in guinea pigs after treatment with dexamethasone at 25 mg/kg. In contrast, TNF levels in mouse serum are inhibited by more than 90% after treatment with dexamethasone at 3 mg/kg. Coincident with the TNF peak in serum is a leukopenia which approaches control levels by 6 h in dexamethasone-treated mice, while remaining depressed in dexamethasone-treated guinea pigs. Treatment with dexamethasone at 25 mg/kg did not save guinea pigs from endotoxin lethality, whereas long-term survival of mice under identical conditions was apparent. These results suggest that the relative glucocorticoid resistance observed in guinea pigs is also apparent in a lethal endotoxin shock model in which dexamethasone does not modulate TNF levels or result in increased survival as occurs in mice. The lack of clear efficacy for steroid therapy in human clinical septic shock trials would suggest that the guinea pig endotoxin model may be a more predictive system than the mouse model for the identification of novel agents useful in the treatment of endotoxin shock.

Osteoarthrosis in guinea pigs: histopathologic and scanning electron microscopic features

Spontaneous cartilage degeneration of the femorotibial joint of male Hartley guinea pigs, 61 to 365 days old, was studied by light microscopy (LM) and scanning electron microscopy (SEM) to determine the incidence, age at onset, and to characterize the early changes. Knee joints of 61 day old animals were histologically and ultrastructurally normal. Focal minimal degeneration characterized by cell and proteoglycan loss with surface fibrillation was first observed by LM on the medial tibial plateau (MTP) in two of five 89 day old animals. Mild lesions characterized by focal surface disruption, primarily in the area of medial tibial plateau not covered by the meniscus, were observed in three of five 89 day old animals by SEM. Light microscopic alterations in knee joints of 4, 5, and 6 month old animals consisted of varying degrees of focal chondrocyte death, decreased toluidine blue matrix staining, and surface fibrillation. Small chondrocytic clones were first observed in medial tibial cartilage of 6 month old animals with moderate focal degeneration. Ultrastructurally, 4, 5, and 6 month old animals generally had moderate to severe fibrillation involving primarily the area of the medial tibial plateau not covered by the meniscus. Tibial osteophyte formation, mild synovial hyperplasia, medial femoral and meniscal cartilage degeneration, were first seen by LM in 9 month old animals. Lesions in 1 year old animals were similar, but more severe and included subchondral sclerosis of medial tibial and femoral bone. Bilateral fibrillation of greater than 50% of the medial tibial articular surface was observed in all 1 year old animals by SEM.(ABSTRACT TRUNCATED AT 250 WORDS)

Interleukin-2 induced systemic toxicity: induction of mediators and immunopharmacologic intervention

Interleukin-2 has been tested as an anti-cancer agent, either alone or in combination with immune cells, but severe dose limiting adverse toxic effects have been observed. Because the pathogenesis of the toxicity has remained uncharacterized, it has not been possible to determine whether the therapeutic and the toxic events could be separated. We have examined immunopharmacologic regulation of IL2 induced mediator induction and toxicity syndrome and have compared this data with our earlier information on IL2 enhancement of immune function in murine systems. The results of this study have shown that treatment with recombinant human interleukin-2 induced increased cellular TNF activity in lymphoid organs and this activity was abrogated by an anti-TNF antibody. Additionally, continuous daily treatment with interleukin-2 also induced increases in serum corticosterone but no detectable increases in serum IL1 or TNF. The increases in serum corticosterone occurred later in the treatment process and coincided with histopathologic changes in the adrenal glands and other tissues. Animals that died as a result of IL2 treatment had ascites and hydrothorax. Histopathologic changes were noted in the lungs, liver, adrenals, kidneys, gastrointestinal tract, heart and lymphoid organs. Cyclophosphamide, dexamethasone and anti-ASGM1 antibody were most effective in increasing survival and inhibiting immune enhancement but differentially effective in inhibiting TNF induction (or in certain cases gamma interferon induction), decreasing ascites or hydrothorax or affecting lymphoid proliferation in the lungs and spleen. Cyclosporin A and azathioprine were not as effective in enhancing survival and had differential effects on the other parameters. Possible mechanisms of both therapeutic and toxic events are discussed.

Antigen-induced edema formation, bronchoconstriction, and pulmonary vasospasm in the isolated perfused guinea pig lung. Evidence for a secondary edemagenic response

The effect of antigen (ovalbumin) challenge on pulmonary hemodynamics, bronchoconstriction, and fluid filtration was investigated in Ringer's-perfused (non-recirculating) lungs that had been passively sensitized in vitro. Bolus ovalbumin injection (30 micrograms) produced immediate increases in pulmonary arterial pressure, peak intratracheal pressure, and lung weight within 1 min and secondary marked increases in intratracheal pressure and lung weight from 120 to 200 min. Electron microscopy of antigen-challenged isolated lungs showed evidence of both septal and intraalveolar edema. Ionophore A23187 (100 micrograms) challenge of nonsensitized lungs produced immediate pulmonary responses similar to antigen, whereas secondary increases in lung weight were smaller. Arachidonic acid pretreatment (1 microM) potentiated immediate antigen-induced increases in intratracheal pressure but did not affect pulmonary responses to ionophore challenge. Putative mediators of anaphylaxis including histamine, leukotrienes B4, C4, D4, and E4, platelet-activating factor, and substance P produced immediate changes in pulmonary arterial and/or intratracheal pressure similar to antigen challenge. Only platelet-activating factor and substance P partially mimicked the secondary edema formation noted following antigen challenge. Thus, antigen challenge in in vitro sensitized guinea pig lungs produced both immediate and secondary responses characterized by increases in vascular pressure, airway pressure, and edema formation. This occurred in the absence of circulating blood-formed elements and without a massive influx of cells. Synergism between mediators such as histamine, the leukotrienes, platelet-activating factor, and substance P released following antigen challenge may be necessary to produce the complete pathophysiological sequelae associated with antigen challenge in the perfused guinea pig lung.

In vivo administration with IL-1 accelerates the development of collagen-induced arthritis in mice

In an attempt to examine the in vivo proinflammatory properties of IL-1, the effects of rIL-1 beta on the development of collagen-induced arthritis in mice were investigated. The results presented in this paper demonstrated that the administration of rIL-1 beta via mini-osmotic pumps into DBA/1 mice which were suboptimally immunized with native chick type II collagen (NcII) markedly accelerated the onset as well as the progression of the arthritic disease. When IL-1-containing osmotic pumps were s.c. implanted onto mice 18 days post-collagen immunization, clinical signs of arthritis appeared within 3 to 4 days after the implant with the pumps. Maximal incidence of arthritis which was usually 80 to 100% occurred between the 6th and 7th day after the administration of rIL-1 beta. Histologic analyses revealed that the knee and ankle joints from mice which were treated with rIL-1 beta for 7 days were most severely and consistently affected. Furthermore, these IL-1-treated mice exhibited granulocytic hyperplasia within the marrow as well as marked peripheral blood neutrophilia. By contrast, arthritis was not observed during the 7-day course of the IL-1 study in the following control groups: 1) mice that were only immunized with NcII, and 2) collagen-immunized mice which received osmotic pumps containing PBS. A substantial number of these collagen-immunized mice which were not treated with IL-1 eventually developed arthritis but at later times after the incidence of arthritis had peaked in the IL-1-treated group. In addition, unimmunized mice failed to develop arthritis upon treatments with IL-1 beta. Moreover, the humoral responses to NcII were not altered in the IL-1-treated mice. Thus, these in vivo studies suggest that IL-1 is potentially capable of triggering the various inflammatory events of collagen-induced arthritis, and thereby, contribute to the pathogenesis of murine arthritis.

In vivo administration with IL-1 accelerates the development of collagen-induced arthritis in mice

In an attempt to examine the in vivo proinflammatory properties of IL-1, the effects of rIL-1 beta on the development of collagen-induced arthritis in mice were investigated. The results presented in this paper demonstrated that the administration of rIL-1 beta via mini-osmotic pumps into DBA/1 mice which were suboptimally immunized with native chick type II collagen (NcII) markedly accelerated the onset as well as the progression of the arthritic disease. When IL-1-containing osmotic pumps were s.c. implanted onto mice 18 days post-collagen immunization, clinical signs of arthritis appeared within 3 to 4 days after the implant with the pumps. Maximal incidence of arthritis which was usually 80 to 100% occurred between the 6th and 7th day after the administration of rIL-1 beta. Histologic analyses revealed that the knee and ankle joints from mice which were treated with rIL-1 beta for 7 days were most severely and consistently affected. Furthermore, these IL-1-treated mice exhibited granulocytic hyperplasia within the marrow as well as marked peripheral blood neutrophilia. By contrast, arthritis was not observed during the 7-day course of the IL-1 study in the following control groups: 1) mice that were only immunized with NcII, and 2) collagen-immunized mice which received osmotic pumps containing PBS. A substantial number of these collagen-immunized mice which were not treated with IL-1 eventually developed arthritis but at later times after the incidence of arthritis had peaked in the IL-1-treated group. In addition, unimmunized mice failed to develop arthritis upon treatments with IL-1 beta. Moreover, the humoral responses to NcII were not altered in the IL-1-treated mice. Thus, these in vivo studies suggest that IL-1 is potentially capable of triggering the various inflammatory events of collagen-induced arthritis, and thereby, contribute to the pathogenesis of murine arthritis.

The progression of the inflammation in established collagen-induced arthritis can be altered by treatments with immunological or pharmacological agents which inhibit T cell activities

Alterations in the progression of the inflammatory disease in mice with established collagen-induced arthritis (CIA) by in vivo treatments with either anti-T cell antibodies or an immunosuppressive drug, whose main targets of action are T cells, were studied. It was demonstrated that the in vivo administration of either monoclonal anti-L3T4, anti-Ly-2 or the combination of anti-L3T4 and anti-Ly-2 failed to modify the inflammatory disease after the arthritis had been initiated. Nevertheless, the progression of disease was decreased by treatments with rabbit anti-mouse lymphocyte sera (ALS) in mice with established CIA. While there was a substantial reduction in the proliferative responses to the T cell mitogen concanavalin A (Con A) in these ALS-treated mice, proliferation to a B cell mitogen, lipopolysaccharide, was unaffected. Furthermore, treatments with anti-Thy-1.2 monoclonal antibody (mAb) by itself did not alter the progression of the ongoing inflammatory disease, but combined treatments with both anti-Thy-1.2 and anti-L3T4 mAb prevented the further advancement of the arthritic disease. Although mice receiving either anti-Thy-1.2 alone or both anti-Thy-1.2 and anti-L3T4 exhibited complete absence of Thy-1+ cells within their inguinal lymph nodes, the proliferative responses to Con A by LN cells from mice treated with the combination of anti-Thy-1.2 and anti-L3T4 were drastically reduced compared to the responses of either the anti-Thy-1.2 or anti-L3T4-treated groups. Finally, daily treatments with cyclosporin A, an immunosuppressive drug which preferentially acts on T cells, were also effective in modifying the clinical course of the arthritic disease in mice with established CIA. These results suggest that immunocompetent cells which express the Thy-1 surface marker, most likely Thy-1+ T cells, may play a role in maintaining and perpetuating the inflammatory disease of established CIA.

Spontaneous cartilage degeneration in guinea pigs

Spontaneous degeneration of the knee joint cartilage in male Hartley guinea pigs was studied by light microscopy in animals aged 3-18 months. Unilateral focal degeneration, characterized by chondrocyte death and proteoglycan loss with surface fibrillation, was observed on the medial tibial plateau in 2 of 5 guinea pigs that were 3 months old. The incidence and severity of the lesions increased with age, and by 12-18 months of age, all animals had moderate-to-severe degeneration of the medial tibial plateau, femoral condyle, and meniscus. Lesions were not present on the lateral aspect of the knee joint in any of the animals.

Progressive chronic osteoarthritis in femorotibial joints of partial medial meniscectomized guinea pigs

The sequential histopathologic alterations in femorotibial joints of partial meniscectomized male and female guinea pigs were evaluated at 1, 2, 3, 6, and 12 weeks post-surgery. Foci of moderate to severe cartilage degeneration were present in the medial tibial plateau and femoral condyle of the operated leg by 1 week post-surgery. At 2 weeks post-surgery, the cartilage degeneration in the operated legs was more extensive and there was evidence of early chondrophyte formation on the medial side of either the femur or tibia in three animals. Changes were progressively more severe at 3, 6, and 12 weeks. Focal areas of minimal to mild cartilage degeneration were in the medial tibial plateau of the contralateral nonoperated leg in some animals at 3 weeks post-surgery and in all animals at 12 weeks post-surgery. Changes in the contralateral leg of meniscectomized guinea pigs have not been described previously. Since cartilage degeneration was often severe by 1 week post-surgery, the model has limited utility for testing agents designed to modify the degenerative process in the operated leg. Milder, more slowly progressive lesions in the contralateral leg may be amenable to therapeutic intervention.

Early histopathologic and ultrastructural alterations in femorotibial joints of partial medial meniscectomized guinea pigs

The articular cartilage from femorotibial joints of partial medial meniscectomized male guinea pigs was evaluated at 24, 48, 72, and 96 hours post-surgery to determine the sequential histopathologic and ultrastructural alterations. At 24 hours post-surgery, histopathologic alterations were in the superficial and middle layers and consisted of degeneration and necrosis of chondrocytes and minimal decreased intensity of toluidine blue matrix staining. Changes in chondrocytes and matrix became progressively more extensive 48 hours after surgery. Ultrastructurally, the changes in the superficial matrix appeared to be the result of loss of the fine granular material interspersed between collagen fibers. At 72 and 96 hours post-surgery, chondrocyte loss was extensive and surface fibrillation was seen. These findings suggested that chondrocyte death was the initial important event which led to progressive severe cartilage degeneration in this model.

Incidence of obstructive uropathy in male B6C3F1 mice on a 24-month carcinogenicity study and its apparent prevention by ochratoxin A

A 24-month study assessed the carcinogenic potential of the nephrotoxic mycotoxin ochratoxin A (OA) in B6C3F1 mice. Three groups of 50 males and 50 females were fed 0.1 or 40 ppm OA in the diet. Obstructive urinary tract disease (mouse urological syndrome [MUS]) accounted for the greatest number of spontaneous deaths in the male mice of control (12/50) and 1 ppm (13/50) dose groups, but the disease was not observed in the males fed 40 ppm OA. The earliest age of onset of clinical signs of MUS was 4 months and the average age of onset was 10.1 months. The first death from MUS was observed at 5 months and average age at death was 12.2 months. The mice were caged in groups of five mice per cage and clustering of cases of MUS was observed. Properties of OA which may be important to its preventive effect include inhibition of growth of gram positive bacteria and the production of polyuria as a result of renal proximal tubular damage.

Ochratoxin A carcinogenesis in the (C57BL/6J X C3H)F1 mouse

The potential carcinogenic effects of the mycotoxin ochratoxin A [(OA); CAS: 303-47-9] were assessed in a 24-month feeding study in male and female (C57BL/6J X C3H)F1 (B6C3F1) mice. The mice were assigned to 3 groups of 50 males and 50 females each; group 1 mice were the controls, group 2 mice were fed 1 ppm OA, and group 3 mice were fed 40 ppm OA. Renal neoplasms, both carcinomas and adenomas, were found only in male mice of the 40-ppm dose group. Fourteen of 49 animals that survived at least 20 months had neoplasms morphologically consistent with renal carcinoma. Renal adenomas were present in some of these mice and in other 40-ppm-group males, making a total of 26 mice with renal adenomas. All male mice of the 40-ppm dose group had nephropathy characterized by varying degrees of renal tubular dilation, attenuation and hyperplasia of lining epithelium, and proliferation of regenerative tubules. Females of the 40-ppm dose group had similar but less severe renal changes but no carcinomas or adenomas. Compound-related renal lesions were absent in the 1-ppm dose group. The incidence of hepatocellular neoplasms was slightly increased in male and female mice fed diets containing OA. These results indicate that OA is a renal carcinogen in male B6C3F1 mice and a hepatic carcinogen in female mice of this strain.

Evaluation of ochratoxin A for mutagenicity in a battery of bacterial and mammalian cell assays

Ochratoxin A (OA), a nephrotoxic mycotoxin, was evaluated for genotoxic potential in a battery of in vitro and in vivo assays. OA was not mutagenic to Salmonella typhimurium, either with or without metabolic activation, in the plate incorporation (Ames) test at concentrations of 50-600 micrograms OA/plate or in the gradient plate assay at concentrations of 0.1-1000 micrograms OA/ml. No induction of unscheduled DNA synthesis was evident in primary cultures of rat hepatocytes exposed to concentrations of OA ranging from 0.000025 to 500 micrograms/ml. In the mouse lymphoma forward mutation assay, exposure of L5178Y TK+/- mouse lymphoma cells to OA did not increase the numbers of L5178Y TK-/- mutants. There was no significant difference between the numbers of sister-chromatid exchanges in cells from OA-treated Chinese hamsters and those in cells from the negative-control animals.

Viridicatumtoxin mycotoxicosis in mice and rats

LD50 studies of viridicatumtoxin were done in rats and mice using oral, intraperitoneal (i.p.), and subcutaneous (s.c.) routes. Mice were given oral doses of viridicatumtoxin up to 350 mg/kg body weight and rats were given doses of viridicatumtoxin up to 150 mg/kg. No deaths occurred in the animals dosed by the oral route. Hepatic alterations of hydropic change and necrosis of centrolobular hepatocytes were observed in mice given 250, 300, or 350 mg/kg viridicatum toxin and were more severe in the mice given the higher doses. No histopathologic alterations were present in the rats dosed orally. Mice were given doses of viridicatumtoxin up to 300 mg/kg, s.c., and rats up to 400 mg/kg. No deaths occurred in the animals dosed by this route. Microscopic alterations in both mice and rats were limited to the injection sites and consisted of coagulation necrosis. The single-dose, 72-h i.p. LD50 for the mouse and the rat was 70 mg/kg and 80 mg/kg respectively. Histopathologic alterations in mice given viridicatumtoxin i.p. included fibrinous peritonitis, large subcapsular areas of hepatic necrosis, single-cell hepatocytic necrosis, splenic lymphoid depletion, and vacuolar degeneration of the myocardium. Rats had splenic lymphoid depletion and fibrinous peritonitis.