Proteoglycan loss and subsequent replenishment in articular cartilage after a mild arthritic insult by IL-1 in mice: impaired proteoglycan turnover in the recovery phase

The reparative responses of articular cartilage after an arthritic insult have not been studied extensively to this day. In the present study, we injected interleukin-1 (IL-1) into knee joints of mice to provoke a mild and transient arthritic insult, and characterized both the catabolic and the subsequent recovery phase. In the catabolic phase, which lasted 2 days after IL-1 injection, proteoglycan (PG) breakdown was profoundly accelerated and PG synthesis was markedly inhibited. Sulfation and polysaccharide synthesis were not affected, yet the number of chondroitin sulfate chains was decreased. The general chondrocyte protein synthesis was not inhibited by IL-1. IL-1 injected every other day for a total of three injections prolonged this catabolic phase and resulted in frank loss of articular cartilage proteoglycans. In the recovery phase, started 3 days after IL-1, PG synthesis was enhanced (1.7 times the normal) and proteoglycans had normal hydrodynamic properties. Remarkably, PG degradation was significantly decreased (approximately 50% of the normal). Zymographic analysis demonstrated enhanced expression of gelatinolytic activities in the extracts of the articular tissues shortly after IL-1 exposure and decreased levels in the recovery phase. We found that the overshoot of PG synthesis and impaired degradation act together to facilitate full cartilage repair 7 days after the last of the three IL-1 injections.

Site-specific cartilage changes in murine degenerative knee joint disease induced by iodoacetate and collagenase

Degenerative joint disease was induced in the knee joints of mice by intraarticular injection of two different stimuli: iodoacetate and highly purified collagenase. Proteoglycan synthesis was measured in vivo at different time points in four topographical areas of the knee joint (central and peripheral parts of the patella and central parts of the medial and lateral tibial plateaus) and was compared with histological observations of localized damage to the joint. In vitro incubation with iodoacetate had a direct effect on proteoglycan metabolism. Intra-articular injection of iodoacetate in vivo inhibited the proteoglycan synthesis in cartilage from the central part of the patella. In the peripheral part of the patella, inhibition on day 1 was followed by stimulation of synthesis on days 3-30. Proteoglycan synthesis also was inhibited in the central parts of the medial and lateral tibial plateaus. The areas with inhibited synthesis had loss of safranin O staining on histology. In vitro incubation with collagenase did not have a direct effect on the proteoglycan metabolism of intact cartilage; this led to the assumption that osteoarthritis after injection of collagenase is caused by ligamentous injury, which leads to an unstable joint. Injection of collagenase in vivo stimulated the proteoglycan synthesis in cartilage from the central and peripheral parts of the patella. In an early stage of the process, the cartilage from the tibial plateaus also was slightly stimulated.(ABSTRACT TRUNCATED AT 250 WORDS)

Cartilage destruction and osteophytes in instability-induced murine osteoarthritis: role of TGF beta in osteophyte formation?

Osteoarthritis is characterized by focal cartilage destruction and marked formation of osteophytes. We have investigated the possible relationship between site specific occurrence of cartilage damage and osteophytes in the collagenase induced murine osteoarthritis model. The degree of instability of the joint correlated with the amount of cartilage loss. Moreover, cartilage damage in the medial tibial plateau correlated only strongly with the osteophyte at the medial plateau, whereas a similar, site directed trend was noted for lateral damage and lateral osteophytes. A separate study with intraarticular injection of TGF beta 1 in normal murine knee joints revealed that this factor can induce osteophytes at characteristic sites, suggesting a role of endogenous TGF beta in this phenomenon.

Selenium deficiency and fulvic acid supplementation induces fibrosis of cartilage and disturbs subchondral ossification in knee joints of mice: an animal model study of Kashin-Beck disease

Kashin-Beck disease is an acquired, chronic and degenerative osteoarticular disorder. Selenium deficiency and fulvic acid in drinking water have been implicated in the cause of this disease. Pathologically, chondronecrosis of the growth plate and articular cartilage and subconsequent disturbance of ossification were observed in the joints. In this animal model study, mice were fed with a selenium deficient diet and fulvic acid supplemented drinking water for two generations. In undecalcified histological preparations of bone we carried out histological staining to detect mineralized and unmineralized bone and cartilage. The results revealed that selenium deficiency and fulvic acid supplementation induced degeneration of the articular cartilage in the knee joints of mice. Dynamic fluorescent labelling of ossification, enzyme histochemical detection of alkaline phosphatase activity in osteoblasts and a typical immunohistochemical localization of collagens type I and II indicated the development of fibrocartilage at the articular surface of knee joints, resembling the early stages of osteoarthrosis. This became obvious by disturbed development of the articular space and meniscus, markedly impaired formation of subchondral bone and early differentiation failure during enchondral ossification. This animal model provides an approach to study the molecular pathogenesis of Kashin-Beck disease.

Histomorphological studies on the effect of recombinant human superoxide dismutase in biochemically induced osteoarthritis

Enzymatic scavenging of .O-2 radicals by injections of superoxide dismutase has been described to inhibit the free radical reactions resulting in tissue damage. Using a biochemically induced model of osteoarthritis (OA) in the knee joints of hens, we investigated the histomorphological alterations under therapy with recombinant human superoxide dismutase (rH-SOD) in various doses by histological-histochemical grading. Treatment of experimental OA with rH-SOD (0.1 mg/0.1 ml intra-articularly) led to a significant reduction in the intensity of cartilage degradation. The pathomorphological alterations in the osteoarthritic cartilage of hens treated with rH-SOD were quantitatively but not qualitatively different from the placebo-treated group. Our results indicate that rH-SOD exerts an inhibitory effect on the deleterious processes on articular cartilage tissue during the course of OA and may counteract cartilage degradations induced or accelerated by oxygen radicals.

In vivo quantification of proteoglycan synthesis in articular cartilage of different topographical areas in the murine knee joint

We developed a method of quantitative measurement of the synthesis of proteoglycans in different areas of the patella and the tibial plateau of the mouse. After incorporation of radioactive sulfate in vivo, the patella was divided with a punch into a central and a peripheral part. A central medial and a central lateral part were taken from the tibial plateau to measure the synthesis of proteoglycans. The synthesis was determined in normal joints and at different intervals after intra-articular injection of sodium iodoacetate and was compared with autoradiographs of whole joint sections. Although considerable variation in sulfate incorporation was found within a group on particular days after induction of osteoarthritis, the variation among experiments was low. Comparison with autoradiographs showed that this new method makes it possible to quantify proteoglycan synthesis by incorporation of radioactive sulfate in different topographical areas of the murine knee joint.

Prolonged effect of iodoacetate on articular cartilage and its modification by an anti-rheumatic drug

The intra-articular injection of iodoacetate into the knee joint of rats produced changes in the articular cartilage which resembled those of osteoarthritis. It caused virtually total loss of many of the oxidative enzymes, indicating inhibition of the main oxidative pathways. Treatment with an anti-rheumatic drug had little early effect but ultimately led to partial restoration of these pathways. The reduced progression of cartilage degradation induced by this drug was accompanied by some unusual histological features.

Estradiol-induced knee osteoarthrosis in ovariectomized rabbits

Experiments in animals have shown that estrogen is chondrodestructive. The existence of 17 beta-estradiol receptor in rabbit chondrocyte and canine cartilage suggests that estrogen is associated with the development of osteoarthrosis (OA). The increased frequency of knee OA in obese postmenopausal women, who are often associated with hyperestrogenism, suggests a link between estradiol and OA. The pathologic changes induced by nine and 12 weeks of intraarticular injection of high doses of estradiol (0.3 mg/kg body weight/day) and low doses of estradiol (0.06 mg/kg body weight/day) into knee joints of ovariectomized rabbits have been examined. In the high-dose group, loss of condyle surface congruity, thinning, fissuring, and fibrillation of the remaining cartilage surface were observed at Week 9. At Week 12, cartilage erosion extended to the calcified layer, exposing the subchondral bone. Scanning electron microscopy (SEM) further revealed numerous pits, which indicated formation of cysts on the cartilage surface. Injection of low dose estradiol, conversely, did not induce significant pathologic changes. The results demonstrated that the direct interaction of estradiol and rabbit cartilage was dose- and duration-dependent. Pathologic changes from the current animal model of knee OA closely resembled those of knee OA in humans. Thus, this model constitutes a potential tool for further studies of the early pathologic changes of OA and the possible prevention of cartilage degeneration by estrogen receptor inhibitors.

[The diagnosis and treatment of osteoarthrosis deformans in subjects in contact with fluorine compounds]

A comparative study is presented of 378 workers with osteoarthrosis deformans (OD) contacting with fluorine compounds and in 106 patients with primary OD. The diagnostic criteria in these two categories of patients coincided. But the pain syndrome in the joints in professional fluorosis (PF) was associated with ossalgias (85%), tenderness of the bones (50.1%) and in 100% by symmetric hyperostosis. OD in PF was accompanied by a more pronounced density, was not accompanied by formation of nodes, and secondary synovitis was 4 times frequent. In OD plus PF males prevailed (96.7 e), and were averagely 10 years younger. In OD+PF treatment diet, calcium agents, glutamic acid should be used that bind and excrete fluorine from the body.

[Effect of SL-1010 (sodium hyaluronate with high molecular weight) on experimental osteoarthritis induced by intra-articularly applied papain in rabbits]

Sodium hyaluronate (HA) with a molecular weight of approximately 600,000-1,200,000 is reportedly effective against osteoarthritis (OA). However, since HA with higher molecular weight is expected to be more effective against OA, we investigated the effects of HA (SL-1010) newly produced by fermentation with a molecular weight of 1,800,000-2,100,000 on the experimental OA induced by intraarticular injection of papain, into the knee joint of the rabbit, in comparison with those of HA with a molecular weight of about 950,000 (HA-95). When 0.4, 0.8, and 1.6% papain (0.5ml) was injected into the knee joint of the animal twice with a 3-day interval, there were dose-dependent degenerative changes and a decrease in sulfated glycosaminoglycan (S-GAG) in the articular cartilage with slight synovial inflammatory changes 6 weeks after the final injection of papain. In this OA model, intraarticular application of SL-1010 slightly reduced the degeneration of articular cartilage, compared with the injections of HA-95 or saline (control). SL-1010 also caused a significant recovery in the S-GAG level which was decreased in the cartilage of the OA model, compared with the control. In addition, SL-1010 inhibited the release of 35S-GAG from the cartilage obtained from normal and OA model joints. These results suggest that SL-1010 is effective in inhibiting the degeneration of cartilage in the OA model, probably due to the recovery of the S-GAG level by reducing the release of S-GAG from the cartilage.

[Effects of SL-1010 (sodium hyaluronate with high molecular weight) on experimental osteoarthritis induced by intra-articularly applied papain in guinea pigs]

Effects of SL-1010 on the experimental osteoarthritis (OA) produced by intra-articular injection of papain, proteolytic enzyme, in the knee joint of the guinea pigs were histologically and biochemically investigated. In addition, experimental conditions to produce OA in guinea pig knee joint were also examined, since papain-induced OA has been mainly studied in rabbits. Six weeks after intra-articular injection of papain (1%, 0.1 ml), there were inflammatory reactions of the synovial membrane, degenerative changes in chondrocytes and the matrix of the articular cartilage, a decrease in the Safranin-O staining intensity and lowering of sulfated glycosaminoglycan. Electronmicroscopic observations revealed that the amorphous layer had disappeared and large bundles of unit collagen fibers and larger collagen fibers had appeared in the cartilage matrix. In the OA model, SL-1010 reduced the inflammatory reactions of the synovial membrane, inhibited development of degenerative changes in chondrocytes and the matrix of the articular cartilage and recovered the Safranin-O staining intensity. The sulfated glycosaminoglycan contents in the cartilage was significantly increased in the SL-1010-treated group, compared with the control group. The electromicroscopically observed charges in the papain-injected knee joint of the control group were rarely detected in the SL-1010-treated group. These results suggest that SL-1010 inhibits degenerative changes in the chondrocytes and the matrix probably by reducing synovial inflammation and protection of the cartilage in the OA model of guinea pigs.

Human recombinant interleukin-1 alpha and beta and articular tissue integrity. An in vivo study on hens and rats

Human recombinant interleukin-1 alpha or beta was injected intraarticularly several times into the knee joints of rats and hens at different dosages (50-2000 ng) and intervals. No loss of cartilage detectable by width of the radiological joint space and no degenerative changes of subchondral bone could be observed during 16 weeks using X-ray analysis. The macroscopical examination of articular cartilage of hens after this period and of rats after one year showed no morphological cartilage damages. These data suggest that human recombinant Il-1 alpha and beta alone may not be sufficient to induce a progressing osteoarthritic process in these animals.

Ultrastructural changes in the synovial membrane in experimentally-induced osteoarthritis of rabbit knee joint

Rabbit knee joint osteoarthritis was induced by intraarticular injections of a 10% sterile NaCl solution. Within 30 days the synovial membrane had undergone hyperplasia resulting in activated synovial fibroblasts. Transitional forms of synoviocytes as well as activated synovial macrophages were a very common finding. At 60 days a thickening of the synovial intima was perceptible. Most of the synoviocytes were of the fibroblast type. Transitional cell forms abounded. An increase in collagen fibres and capillaries of the fenestrated type occurred in the intercellular spaces. In the deep layer collagen bundles had formed between which activated fibroblasts and macrophages were noticed. The described changes point to an active participation of the synovial membrane in the destruction of articular cartilage in osteoarthritis.

Inhibition of estradiol-induced early osteoarthritic changes by tamoxifen

Previous studies on osteoarthritic changes induced by intraarticular injections of estradiol benzoate (EB) suggest estrogen as a risk factor in the development of knee osteoarthritis (OA). The present study observed the anti-arthritic effects of tamoxifen (TMX). Oophorectomized rabbits were subjected to intraarticular injections of vehicle control, EB, TMX, or EB/TMX for 3 weeks. The cartilage changes were assessed by light and scanning electron microscopic examination, enzyme histochemical analysis, and the amount of alcian blue stain binding to glycosaminoglycans. EB injections resulted in cell necrosis, chondrocyte clonings, and pittings, whereas the vehicle control, TMX, and EB/TMX-injected groups showed no histologic abnormalities. Histochemical analysis showed that the numbers of lactate dehydrogenase (LDH)-reactive chondrocytes in the EB-injected group were significantly reduced when compared to other groups (p less than 0.001). The injections of EB/TMX significantly reduced the chondrocyte numbers in the lateral superficial layer (p less than 0.05), compared with the vehicle injection. TMX-injected group revealed slight although insignificant decreases in chondrocyte numbers. The amount of alcian blue stains, representing the relative amount of proteoglycans, significantly decreased only in the superficial layer of the EB- and EB/TMX-injected groups (p less than 0.05). TMX, when concurrently injected with EB, antagonized the chondrodestructive effects of estradiol at the early stage of knee OA in rabbits. The results suggest the potential therapeutic use of TMX at the early stage of OA.

Rapid induction of early osteoarthritic-like lesions in the rabbit knee by continuous intra-articular infusion of mammalian collagenase or interleukin-1

Aminophenyl mercuric acetate (APMA)-activated collagenase (C) (60 U/ml) obtained from in vitro cultures of human skin fibroblasts or recombinant interleukin-1 beta (IL-1 beta) (200 U/ml) was infused continuously for 7 days into the rabbit knee synovial space by means of an implanted Alzet osmotic pump. In stability studies in vitro, activated C or IL-1 incubated for 7 days at 37 degrees C, showed no significant loss of biological activity. Alterations in knee cartilage morphology and proteoglycan (PG) content were determined histologically, and the incidence of cartilage damage calculated. C or IL-1 vehicles infused for 7 days, caused no damage. Incidences of damage for C or IL-1 (n = 8-9), respectively, were as follows: loss PG: 88% and 100%; chondrocyte disorganization and loss, 50% and 78%, fissures and or fraying, 25% and 78%; and convergence of inflammatory cells, 25% and 66%. These results confirm the important role of C and IL-1 in cartilage damage.

[Effect of neurotropin on experimental osteoarthritis]

The effect of Neurotropin on osteoarthritis was investigated in comparison with those of prednisolone and indomethacin. 1) There were remarkable decreases in the staining intensity to safranin-O and in the contents of uronic acid, total hexosamine and hexose in the articular cartilage of rabbits in which experimental osteoarthritis was induced by the injection of papain into the knee joint. In the Neurotropin-treated group, the decrease in the staining intensity to safranin-O and the contents of uronic acid, total hexosamine and hexose were evidently recovered. On the other hand, in the prednisolone- or indomethacin-treated group, the degeneration of the cartilage was even more pronounced than in the control group treated with papain alone. 2) Neurotropin had no effect on the autolytic degradation of cartilage, but promoted the incorporation of 14C-acetate into the proteoglycan in the articular cartilage of rabbits. 3) Both prednisolone and indomethacin inhibited the autolytic degradation and the incorporation of 14C-acetate into the proteoglycan. These results suggested that the therapeutic effect of Neurotropin on osteoarthritis may be due to the improvement of decreased proteoglycan content in the matrix of articular cartilage; and in this respect, it is different from anti-inflammatory drugs such as prednisolone and indomethacin.

[Pharmacologic studies on the antidegenerative effect of ademetionine in experimental arthritis in animals]

A standardized pharmacological model of biochemically induced osteoarthritis in the knee joint of laboratory animals was used for the study of a possible antidegenerative effect of ademetionine (S-adenosyl-methionine, active substance of Gumbaral) in-vivo. Four days after the initial induction of osteoarthritis by 2 intraarticular injections of 0.6 mg sodium iodoacetate into the left knee joint of adult hens, the therapy started with once-weekly intraarticular doses of 0.5 mg, 1.0 mg and 2.0 mg ademetionine over a period of 14 weeks. Quantitative monitoring of the intensity and progression of osteoarthritis was performed every 2 weeks by joint space measurements, topographic-radiological evaluations, and by a macroscopic post-mortem assessment of the joint cartilage and bone. These objective analytical parameters clearly demonstrated that weekly intraarticular doses of 1.0 mg ademetionine significantly reduced the intensity of degenerative processes compared to the placebo (saline) treated joints. The antidegenerative effect of doses of 0.5 mg or 2.0 mg ademetionine were less pronounced and of no statistical significance. Our findings indicate an interesting therapeutic potency of ademetionine in experimental osteoarthritis and confirm the positive clinical observations as well as in-vitro results with this new drug by other researchers.

Osteoarthrosis induced by intra-articular hydrogen peroxide injection and running load

Osteoarthrosis of the rat knee joint was induced successfully by intra-articular injection of 2% hydrogen peroxide (H2O2) and running load. In the group receiving two injections of physiological saline with running load, no histological osteoarthrotic knees were developed up to 8 weeks after the injection. In the group receiving two 2% H2O2 injections and running load, advanced osteoarthrosis occurred in all knees 8 weeks after the first injection, and the Mankin's score of osteoarthrotic knees appeared to be higher than the group receiving two 2% H2O2 injections without running load (p less than 0.004, Kruskal-Wallis H test). In the rats receiving a single 2% H2O2 injection with running load and a vitamin E-enriched diet, the inhibitory effect of vitamin E on the development of osteoarthrosis was statistically significant compared to the regular diet group (p less than 0.05, Wilcoxon rank test).

Estrogen use and radiographic osteoarthritis of the knee in women. The Framingham Osteoarthritis Study

Female participants of the Framingham Osteoarthritis Study (n = 831, mean age 73, age range 63-93) were evaluated for osteoarthritis with weight-bearing radiographs of the knee during 1983-1985. At each biennial examination (1963-1981), the women were asked about their use of estrogen during the previous 2 years. We categorized estrogen use as no use reported, use reported at 1 examination, or use reported at 2 or more examinations. We found no positive association of estrogen use with radiographic knee osteoarthritis after controlling for age, body mass index, age at menopause, physical activity, history of knee injury, and smoking. In fact, a modest but nonsignificant protective effect for both radiographic osteoarthritis (odds ratio 0.71, 95% confidence interval 0.42, 1.20) and severe radiographic osteoarthritis (odds ratio 0.66, 95% confidence interval 0.33, 1.32) was seen in women who reported estrogen use at 2 or more examinations. Subgroup analyses also showed no association between estrogen use and radiographic knee osteoarthritis. We conclude that estrogen use in women is not associated with an increased risk of radiographic knee osteoarthritis.

Degenerative knee joint lesions in mice after a single intra-articular collagenase injection. A new model of osteoarthritis

A single intra-articular injection with bacterial collagenase in the right knee joints of 10-week-old male C57bl10 mice led to osteoarthritic lesions within a few weeks in these joints. The collagenase-induced osteoarthritis was characterized by severe degenerative cartilage lesions on the medial side of the femorotibial joint associated with patellar dislocation to the medial side of the joint, sclerosis of subchondral bone below the cartilage erosions, osteophyte formation, and consequent deformity of the knee joints. The osteoarthritic alterations in the collagenase model closely resembled the changes observed in spontaneous osteoarthritis in aged mice. The intra-articular injection with collagenase probably results in damage to collagen type I-containing joint structures, such as tendons, ligaments and menisci, leading to an instable knee joint that results in the osteoarthritic joint lesions observed in this model. The collagenase-induced osteoarthritis model offers the possibility of studying experimental osteoarthritis in large animal groups of inbred strains within a restricted time span at low costs.

Development of osteoarthritic lesions in mice by "metabolic" and "mechanical" alterations in the knee joints

Male, 10-week-old C57B1 10 mice received a single intraarticular injection in the knee joints with papain, iodoacetate, or collagenase. This led to osteoarthritic lesions, such as matrix depletion, chondrocyte proliferation, and osteophyte formation, in the injected knee joints within several weeks. After injection of iodoacetate and papain, the main osteoarthritic alterations were localized in the femoropatellar joint, whereas injection of collagenase led to marked osteoarthritic lesions in the femorotibial joint. The mechanism of induction of these alterations appears to differ for iodoacetate and papain on one site and collagenase on the other site. Data are presented that collagenase injection, by way of damaging ligaments and tendons, destabilizes the knee joint eventually leading to osteoarthritic alterations. In contrast, injection of papain or iodoacetate directly interferes with cartilage metabolism resulting in osteoarthritic changes.

[The dose dependent effect of glycosaminoglycan peptide complex on corticosteroid-induced disordered metabolism in cartilage tissue of rats]

Systemic corticosteroid treatment induces morphological and functional changes in the articular cartilage similar to those in human osteoarthritis. In animal experiments the dexamethasone-induced inhibition of chondrocyte metabolism can be reduced in a dose-related manner by concomitant treatment with glycosaminoglycan-peptide complexes (GP-C)***). The metabolic changes in cartilage tissues of the joint and Processus Xiphoideus measured quantitatively by 35S-sulphate incorporation are comparable. The results indicate that GP-C could also have a dose-related effect on human osteoarthritic cartilage.

[Monoiodoacetic acid-induced arthropathy of the rabbit knee--a contribution to the pathogenesis of arthrosis]

A chemically-induced joint degeneration was produced by an one-time intraarticular injection of the glycolysis inhibitor monoiodic acetate into the rabbit knee joint (32 joints of 16 rabbits + 4 control animals). The investigation is founded on Kalbhen's animal model of osteoarthrosis and on Salter's and Moskowitz' experiments. Histomorphological examinations were done in intervals of 1 day to 12 weeks. The results raise several open questions in experimental as well as clinical aspects. On that account these results were discussed pathogenetically in the view of the own pathophysiological and biocybernetical conception of osteoarthrosis development.

[Experimental arthrosis caused by chemical cartilage damage]

In experiments on rabbits the authors studied the dynamics of cartilage degeneration and subsequent pseudorepair processes following what was doubledose chemical damage to articular cartilage. In addition to the classical histological methods they used the histochemical demonstration of hydrolase and dehydrogenase which are of prime importance to cartilage. The intraarticular instillation of sodium iodacetate caused major and irreversible damage to the whole cartilaginous layer. Subsequent pseudorepair proceeded on the one hand from the cells of the peripheral synovial membrane and on the other to a lesser extent from the fibroblasts of the subchondral bone marrow. The most important enzymes depicting these processes can be regarded as AP and LDH. From the viewpoint of accessibility of dystrophic articular cartilage to repair cells one must distinguish the central part of the joint from its periphery. In the latter area of the cartilage it were mainly synovial cells which took part in repair and pseudorepair takes place considerably more actively here than in the central parts of the joint.

The influence of NSAIDs on morphology of articular cartilage

A large number of experimental data have given evidence that many NSAIDs can inhibit the synthetic processes of connective tissue in-vitro and ex-vivo. During the past 18 years we have investigated the in-vivo effect of antirheumatic drugs on knee joint cartilage using rats and hens. Single or once-weekly intraarticular injections of salicylates, indomethacin, phenylbutazone, naproxen, ibuprofen, clofezone, fufenamic acid, niflumic acid, or dexamethasone induced morphological alterations in the joint cartilage and subchondral bone, which were demonstrable by means of histology, stereoelectron-microscopy, biochemistry and X-ray. The cartilage of these laboratory animals had a faster turnover compared to man, and the degenerative and destructive processes occurred within 8-12 weeks and were identical or very similar to osteoarthritis in man. In contrast to the general opinion that all NSAIDs possess more or less the same pharmacological properties, the influence of these drugs on articular cartilage was, surprisingly, quite different. In our animal experiments we found that comparable doses between NSAIDs, such as fenbufen, ketoprofen, diclofenac, and tiaprofenic acid, did not induce any degenerative processes in cartilage and subchondral bone in-vivo. A documentation of our radiographical, macroscopical and histomorphological results demonstrated the pronounced differences between NSAIDs on joint tissue. Our experimental data suggested that in the pharmacotherapy of osteoarthritis a specific selection of NSAIDs between those with catabolic and those with non-catabolic characteristics in regard to connective tissue metabolism was important and beneficial.

The induction of an erosive arthropathy in the guinea pig with copper II bisglycinate and its treatment with antirheumatic drugs

Single intra-articular injections of copper II bisglycinate [Cu(II)gly] (30-300 micrograms) into guinea-pig knee joints induce progressive joint degradation which first appears after about 2 weeks and peaks about 12 weeks after injection. The stable complex, copper II bishistidinate (300 micrograms) was without effect. The Cu(II)gly induced syndrome has features more in common with osteoarthritis than rheumatoid arthritis in that erosion occurs in the absence of persistent synovial inflammation. The possibility that the damage may be caused by Cu(II)gly inducing free radical formation within the joint, leading to a self-perpetuating chain reaction is discussed. D-Penicillamine and other drugs were tested for their effects on the histological changes induced 4 weeks after the intra-articular injections of 100 micrograms Cu(II)gly. Few significant effects were observed and these were restricted to D-penicillamine, which caused inconsistent protection, sodium aurothiomalate which protected at a dose causing weight loss and prednisolone which exacerbated joint damage. It is concluded that the variability of the control response will need to be reduced before the model can be used for routine drug evaluation but it may be of value in the study of chronic degradative joint disease.

Chemical model of osteoarthritis--a pharmacological evaluation

For pharmacological testing of drugs with antidegenerative potency we developed an animal model of biochemically induced osteoarthritis (OA) by blocking the glycolytic energy metabolism and synthetic processes in articular chondrocytes. After local injection of sodium iodoacetate osteoarthritic reactions will progress within 2-4 months. Using a standardized radiological, histological, and macroscopical grading we could demonstrate that corticosteroids and some NSAID exert negative effects on articular cartilage, while a few other NSAID showed no influence. Diclofenac had even a pronounced antidegenerative potency which was comparable to the antiosteoarthritic properties of two glycosaminoglycan derivatives investigated in the model of biochemically induced OA in the knee joint of hens and rats.

Oral contraceptives, cigarette smoking and other factors in relation to arthritis

The data on oral contraceptive use and arthritis in the Oxford-Family Planning Association contraceptive study have been analysed. For rheumatoid arthritis, the rate of first referral to hospital was 0.33 per 1000 woman-years in those who never used oral contraceptives (27 cases), 0.33 per 1000 woman-years in ex-users of oral contraceptives (29 cases) and 0.44 per 1000 woman-years in current users of oral contraceptives (22 cases). Likewise, there was no important association between oral contraceptive use and other forms of arthritis. An unexpected finding was a strong association between referral to hospital for rheumatoid arthritis and cigarette smoking; the rate in women never smoking was 0.27 per 1000 woman-years (34 cases) and in those smoking 15 or more cigarettes per day was 0.64 per 1000 woman-years (19 cases).

Immobilization ameliorates chemically-induced articular cartilage damage

We have previously shown that immobilization protects against the development of mechanically-induced osteoarthritis following-anterior cruciate ligament transection in dogs. Herein, we examine the effect of immobilization of the leg on the chemically-induced degeneration of femoral articular cartilage caused by intraarticular injection of iodoacetate in guinea pigs. One week after the injection, cartilage from animals which were not immobilized exhibited a decrease in Safranin O staining and a 10-20% reduction in the number of chondrocytes. Three weeks after injection, cell death and loss of Safranin O staining had progressed, and surface fibrillation and osteophytes had developed. Articular cartilage from the contralateral (uninjected) knees of guinea pigs which received iodoacetate, and from knees of animals which were immobilized for 1 week but did not receive iodoacetate, was histologically and histochemically normal. However, specimens from 2 of 4 untreated knees which were immobilized for 3 weeks showed a reduction in Safranin O staining. Immobilization of the knee did not alter the loss of Safranin O staining seen after intraarticular iodoacetate injection, but did reduce the depletion of chondrocytes (P less than 0.05). Furthermore, neither osteophytes nor fibrillation developed in any of the animals which were constrained after iodoacetate injection. Thus, immobilization was clearly protective in this model of chemically-induced cartilage injury.

[An experimental model of osteoarthritis. II.- Biochemical study of collagen and proteoglycans]

We investigated biochemical modifications of the initial phase of cartilage degradation in an osteoarthritic model developed in the rabbit by intraarticular papain injection. The amino-acid composition of the collagen did not differ significantly between control and papain-treated groups. After 3H-proline in vivo incorporation, the absence of radioactivity in peaks beta 12 and alpha 2 shows that cartilage did not synthesize type I collagen in noticeable quantity during the labelling period. The study of proteoglycans by the use of the "fixed charges density" (FCD) shows that in our model they decreased rapidly and substantially, as in human disease. The decrease was measurable from 1 h after injection with a minimum at about 24 h (54% of the normal level). However, increased 35SO4 incorporation was observed, beginning very soon after injection and passing through a maximum (500% of the normal level) around the 3rd day. The rates of 3H-proline incorporation and 3H-hydroxyproline formation were decreased in the treated cartilage in a similar way as for the proteoglycans, with a minimum (55% of the normal level) at about 24 h. The "turn-over" of 3H-hydroxyproline and "non collagen" 3H-proline were increased in the treated cartilage. The half-lives of both amino-acids went respectively from 26 to 15 days and from 14 to 10 days. Injection of papain in the rabbit knee-joint produced a major loss of ground substance and a reaction of the chondrocytes. The cells metabolism seemed modified with especially a catabolism stimulation.

[An experimental model of osteoarthritis. I. Induction and ultrastructural study]

Starting from Bentley's works [2], we elaborated an experimental model of arthrosis easy to use, providing reproducibility of effects and showing the same development as the human disease, but within a far shorter time. Papain injection induced a quick, high loss in proteoglycans. A rapid, localised chondrocyte reaction in the middle layer of the support area was noted. In this area, cells rapidly showed hyperactivity signs and a crown of microfibers taking the amyloid tissue-specific staining was seen around them. The building of such crowns might result from a discrepancy between collagen and proteoglycan secretion inducing a modification in their inter-relations. We also noticed binucleate cells, someones being in process of division, which might be the beginning of clones.

Hemarthroses and warfarin: joint destruction with anticoagulation

A 56 year old man was seen because of recurrent right shoulder hemarthroses and a superior vena caval syndrome. Intermittent symptoms had occurred for six years and resulted in marked destructive changes in the right shoulder. Arthroscopy added pathological evidence of this unusual mechanism of arthropathy. Patients on anticoagulants deserve close attention to symptoms of occult bleeding.

Induction of osteoarthrosis in the guinea pig knee by papain

The main purpose of this investigation was to develop a model for experimental induction of osteoarthrosis. A previously described method using papain was tried on guinea pig knee joints. Eighteen adult guinea pigs were given papain intra-articularly in the right joints; the left joints were used as controls. The animals were killed after 6 hours, 1 week, 2 weeks, 2 months, 4 months, 6 months, 8 months, and 10 months. Specimens of the articular cartilage were removed for histologic and histochemical investigation. Microscopic surface irregularities could be observed in the animals after 6 hours, 1 week, and 2 weeks, and again after 8 and 10 months. Histochemical examination of the sections from the experimental joints indicated a loss and degradation of the sulfated glycosaminoglycans. This loss was evident after 6 hours, 1 week, 2 weeks, and 8 months. The first osteoarthrotic changes were observed macroscopically after 8 months. Radiographic changes in the experimental joints could be observed in all animals killed after 10 months. It was concluded that osteoarthrosis similar to that occurring in humans can be induced by this method.

[Radiological changes in the region of the patella in chronic alcoholics (author's transl)]

The author has reviewed the changes in the patello-femoral joint seen on plain films in 41 male alcoholics. These are due to the effect of hyperlipoproteinaemia type IV on the patello-femoral joint. These joints show bilateral secondary arthrosis. At the same time as these erosions and defects of the articular surface develop, there are also changes in the femoro-tibial joint.

The reaction of cartilage and osteophyte formation after the intraarticular injection of papain

A histological and autoradiographical study on the reaction of chondrocytes and the growing processes of osteophyte after the intraarticular injection of papain was carried out. The degenerating processes--fibrillation, death of chondrocytes and erosion--were observed as early as 1 day after the injection, and acid mucopolysaccharide staining with safranin-O was completely lost throughout the articular cartilage 1 week after the injection. The regenerating or proliferating figures--chondrocytes mitosis, thickening of fibrous tissue--were observed as early as 3 days after the injection and chondrocyte clusters were noted after 1 week of injection. Four weeks after injection, proliferating processes were more obvious than degenerating processes, safranin-O stainability had recovered and the proliferative figures of cartilage and fibrous tissue became more obvious. As blood vessels invaded into the cartilage and thickened fibrous tissue, osteophyte began to form in these tissues. Four types of growing processes of osteophyte were observed. Hypertrophy of articular cartilage was observed, and new hyaline articular cartilage appeared to be formed through metaplasia from fibrous tissue. Including the osteophyte formation, tremendous regenerating or repairing efforts of chondrocytes and fibroblasts were observed. These results appear to indicate that cartilage has some ability to regenerate and to repair itself if it could avoid further damage.

Reversibility of systemic corticosteroid-induced mandibular osteoarthritis: an experimental study in A/J mice

Immature A/J mice were treated for up to seven weeks with intermittent systemic doses of triamcinolone hexacetonide (4 mg/kg body weight) and were than allowed to recover for seven weeks. Morphological studies were performed on the mandibular condylar cortilage of treated and control animals. By the third dose, obvious structural changes were seen within the cartilaginous matrix. The latter appeared first in the midst of the condylar cartilage and, in the more severe cases, also involved the articular surface. The hormonal catabolic influence intensified progessively so that by the end of the experimental period, most condyles had undergone severe degenerative changes in the form of cartilage fibrillation and ulceration. After the recovery period, experimental condyles had regained their normal appearance. Thus, although intermittent systemic administration of corticosteroid hormone tends to induce osteoarthritic changes in the mandibular joint of the mouse, the mice possess the capacity to undergo full recovery shortly after the termination of the hormonal treatment.

Fresh immature articular cartilage allografts. A study on the integration of chondral and osteochondral grafts both in normal and in papain-treated knee joints of rabbits

The integration of immature cartilage allografts to knee joints of both normal rabbits and those submitted to arthritis through papain was studied for a period of up to 9 months. Two types of grafts were compared: chondral--constituted only by cartilage, and osteochondral--cartilage plus a thin layer of subchondral bone. The integration of the grafts was analyzed through inspection of the articular surface and histologic sections. The viability of the grafts was checked through the incorporation of 35SO4 on the chondral matrix. The following conclusions were drawn: (1) A large member of the grafted cartilages were well accepted without histological evidence of immunological rejection, and metabolically active 9 months after transplantation. (2) The chondral graft was found to be superior to the osteochondral one regarding the integration, but both showed tendency to degeneration with time. (3) The presence of arthritis previously induced by papain affected the integration of the grafts causing a higher precentage of degeneration on the grafts causing a higher precentage of degeneration on the grafted cartilage.

[Animal experiment studies on the effect of intra-articular injections of antiphlogistic-antirheumatic agents on articular cartilage in vivo]

Animal experiments have shown that weekly intraarticular injections of various antiphlogistic/antirheumatic drugs into the knee joint induce progressive degenerative alterations in joint cartilage. The observed degenerations and destructions are most similar to the pathophysiology of osteoarthrosis in humans. By X-ray and macroscopic techniques the degenerative processes can be studied qualitatively and quantitatively. A decrease of joint space is a sensitive and early indicator of osteoarthrosis and showed that 10 weeks after intraarticular application of Ibuprofen, Phenylbutazone, Oxyphenbutazone, Flufenamic acid, Niflumic acid, Na-salicylate, Clofezone, Bumadizone and Dexamethasone the degenerative alterations in the injected knee joints were more severe than by applications of Chloroquine,D-penicillamine, Salicylamide and Indometacin. The degenerative effect on articular cartilage by the investigated drugs can be explained by their inhibitory potency on anabolic metabolism of connective tissue. The results of our animal experiments lead to the conclusion, that antiinflammatory drugs may also in man induce or accelerate degenerative joint diseases especially after long term treatment with high doses of these drugs.

Absence of increased frequency of degenerative joint changes after osmic acid injections

Fifty-two adults and 31 children, who were treated with osmic acid for one knee joint, were observed for 8-18 years. No other local treatment of the knee joints was given. In adults no difference was seen in clinical or radiological findings between joints treated and not treated with osmic acid. The age of the patient had a marked influence on the development of degenerative joint disease. In children, radiological deterioration of the knee joints was marked in joints affected by radiological changes even before treatment. It is concluded that though osmic acid causes superficial damage to the cartilage, it has no significant clinical relevance. Osmic acid can still be recommended as a simple remedy in the treatment of knee joint synovitis, in both adults and children.

Papain-induced changes in the knee joints of adult rabbits

Rapidly progressing joint disease can be produced in the rabbit by intra-articular injection of concentrated papain. With the use of radioactive thymidine it is possible to demonstrate that the cartilage cells recover their ability to divide by mitosis at the same time as degenerative changes appear in the cartilage. Clusters of chondrocytes arise by mitosis of chondrocytes and not by a floating together of cartilage cells.

Experimentally induced osteoarthrosis in the temporomandibular joint of the mouse

(1) 6-week-old ICR mice were injected daily with pharmacologic doses of triamcinolone diacetate (1.5 mg/kg body weight) for 8 consecutive weeks. (2) The temporomandibular joint served as a model for histological and histochemical examinations concerning the effect of glucocorticoid hormone upon bone and cartilage. (3) Histochemical reactions indicated a large number of lipid droplets within the peripheral vasculature. (4) Histological examinations revealed pathologic features, indicative of primary osteoarthrosis.

Articular cartilage studies and osteoarthrosis

Osteoarthrosis is characterized in the early stages by degradation of articular cartilage matrix. Clinical, radiological, and pathological studies have failed to reveal the factors which initiate the breakdown of cartilage and are not applicable to detailed sequential studies of the affected tissues at all stages in the disease. Therefore animal experiments have been employed to provide more information on degradation and repair process in cartilage. These studies have demonstrated: 1) Matrix protection and induced repair of mature articular cartilage by the use of oral aspirin after lacerative injury. 2) Establishment by the intra-articular injection of the plant enzyme papain of a model of osteoarthrosis in the rabbit hip which mimics human osteoarthrosis and is suitable for further experimental studies. 3) A proliferation of mature articular cartilage chondrocytes in response to loss of matrix, which indicates a latent repair capacity. 4) Repair of extensively damaged hip joints after femoral osteotomy by increased formation of subchondral new bone and formation of fibrocartilage on the articulating surfaces. These tissue repair processes are associated with an increase in vascularity of the femoral head and acetabulum produced by the osteotomy. 5) Succesful transplantation as allografts in both normal and arthrotic rabbit knees of aggregates of epiphysial chondrocytes isolated from their matrix. This method of joint surface replacement may have clinical applications.