Glycosaminoglycan Content Of Cartilage Research Articles

In vivo protection against interleukin-1-induced articular cartilage damage by transforming growth factor-beta 1: age-related differences.

Transforming growth factor-beta (TGF-beta) has been shown to antagonise interleukin-1 (IL-1) effects in different systems. Investigations were carried out to study whether TGF-beta 1 modulates IL-1 induced inflammation and IL-1 effects on articular cartilage in the murine knee joint. IL-1, TGF-beta 1 or both factors together were injected into the knee joint. Inflammation was studied in whole knee histological sections. Patellar cartilage proteoglycan synthesis was measured using 35S-sulphate incorporation while patellar cartilage glycosaminoglycan content was determined with automated image analysis on joint sections. Co-injection of TGF-beta 1 and IL-1 resulted in synergistic attraction of inflammatory cells. In contrast, TGF-beta 1 counteracted IL-1 induced suppression of articular cartilage proteoglycan synthesis. Proteoglycan depletion was similar shortly after the last injection of IL-1 or IL-1/TGF-beta 1, but accelerated recovery was found with the combination at later days. This protective effect of TGF-beta 1 could not be demonstrated in older mice. TGF-beta 1 aggravates IL-1 induced knee joint inflammation, but counteracts the deleterious effects of IL-1 on articular cartilage proteoglycan synthesis and content. The data indicate that TGF-beta 1 could play an important part in articular cartilage restoration after IL-1 induced proteoglycan depletion.

Long‐distance running causes site‐dependent decrease of cartilage glycosaminoglycan content in the knee joints of beagle dogs

To study the effects of a long-term (1-year) program of running exercise (up to 40 km/day) on the thickness and glycosaminoglycan (GAG) content of articular cartilage in the knee and humeral head cartilage of young dogs. Samples for histologic analysis were obtained from 12 different locations of the joints. We conducted a detailed, area-specific analysis, measuring the thickness of articular cartilage and analyzing the distribution of Safranin O stain that binds stoichiometrically to GAG as determined by quantitative microspectrophotometry. Running exercise decreased the GAG content of the uncalcified articular cartilage in the weight-bearing summits of the femoral condyles by 5-13% (P < 0.05), while at margins of these areas the GAG content was equivalent to control levels. In the lateral condyle of the femur, the reduction was most prominent in the superficial zone (up to 28% decrease; P < 0.05), and extended into the intermediate zone (11% decrease; P < 0.05). GAG content was also significantly reduced in the superficial zone at the lateral condyle of the tibia and the head of the humerus, by 35% (P < 0.01) and 15% (P < 0.05), respectively. Running did not alter GAG concentration in the patellofemoral region. The GAG depletion caused by 40-km/day running exercise is restricted to prominent weight-bearing areas of the joint and begins from the superficial cartilage without signs of degeneration. The different degree and type of joint loading can explain the site-dependent cartilage response to long-distance running. The loss of GAGs was possibly due to breakdown of proteoglycans, which could not be compensated for by neosynthesis of molecules. With time, this may affect the condition of articular cartilage, especially if the joint is exposed to loading for lengthy periods.

Prevention of adjuvant arthritis by cyclosporine in rats

The effect of cyclosporine A during the development phase of adjuvant arthritis was studied in 40 female rats. Five groups of eight animals each received oral cyclosporine, 2.5, 5, 10, 20, or 30 mg/kg daily for 30 days. Also, eight normal and eight diseased rats served as placebo controls. At the time of inoculation of the adjuvant suspension on day 0, measurement of disease parameters (paw swelling and vertebral density) was started concomitantly with beginning of therapy. On completion of the study, the animals were killed, and after measurement of total skeletal and segmental (hind legs and caudal spine plus two caudal vertebrae) calcium, the two assessed vertebrae and both femoral condyles were removed for histomorphometric evaluation (vertebrae) and for estimation of glycosaminoglycan (GAG) content of cartilage. Blood for osteocalcin determinations also was taken at term from control and untreated arthritic rats and from animals that had received 10 mg/kg cyclosporine. Treatment with 2.5 mg/ kg was ineffective, but doses between 5 and 20 mg/kg prevented the development of articular and osseous lesions. The 20 mg/kg dose showed no better effect than 10 mg/kg. This was shown by the absence of inflammation and the presence of normal condylar GAG and total mineral content in the areas screened. Untreated animals showed marked reductions in all of these parameters. The 30 mg/kg dose was effective in blocking the GAG loss, but significant reductions in bone density and trabecular volume were seen. There was a close correlation between GAG and bone density values, suggesting a common causal relationship. Circulating osteocalcin was significantly elevated in the untreated animals with adjuvant arthritis. The administration of 10 mg/kg cyclosporine reduced this parameter considerably but not to basal levels. In conclusion, cyclosporine effectively prevented the development of experimental arthritis and associated bone mineral loss in oral doses of 5 to 10 mg/kg; 20 mg/kg showed no better effect than 10 mg/kg, and the 30 mg/kg dose produced toxic skeletal demineralization.

An experimental model of osteoarthrosis in the temporomandibular joint of the rabbit.

Degenerative changes in the temporomandibular joint were induced in 24 rabbits by surgical perforation of the disk. The incongruence obtained between the joint surfaces caused a gradual increase in macroscopic and microscopic changes, including gross remodeling, loss of tissue volume, and altered cell morphology within a 16-week observation period. These changes occurred concurrently with major alterations in the composition of the matrix, as demonstrated by increase in the glycosaminoglycan content of both condylar cartilage and disk and by loss of hydroxyproline in the disk. The lesions in the disk tissue were clearly discernible, whereas those in the condylar cartilage were less extensive. The described method is concluded to give alterations in the temporomandibular tissues, as seen in degenerative joint disease of an early stage.

The effect of chronic paracetamol administration to rats on the glycosaminoglycan content of patellar cartilage

Male Wistar rats were treated with paracetamol (200 mg/kg twice a day) for 2, 3, 4 and 9 weeks. During the first four weeks of paracetamol administration the serum sulfate concentration was significantly decreased. However, during the fourth until the ninth week, the serum sulfate concentration was only diminished to a small and insignificant extent. The paracetamol administration did not lead to serious liver or renal toxicity, as determined by alanine aminotransferase and creatinine levels in the serum of the rats. The paracetamol-induced serum sulfate depletion, observed during the first four weeks of the experiment, led to a significantly lower glycosaminoglycan content of the patellar cartilage of the rats after three and four weeks paracetamol treatment. When after the fourth week the serum sulfate concentration rose to nearly normal levels also the glycosaminoglycan content in the rat patellar cartilage reached control levels. These data indicate that the serum sulfate depletion might be the causative factor for the observed reduction in glycosaminoglycan content of rat patellar cartilage.

Effects of movement and weightbearing on the glycosaminoglycan content of sheep articular cartilage

Immobilised non-weightbearing joints show significant loss of proteoglycan. It is unclear whether this is due to a lack of compression, a lack of movement, or both. Evidence suggests that movement alone is insufficient to maintain proteoglycan levels. To investigate this problem, 20 sheep were divided into four groups and the right forelegs subjected to (1) normal weightbearing and movement, (2) movement without weightbearing, (3) weightbearing without movement and (4) non-weightbearing without movement. After one month, full thickness core samples of cartilage taken from the radio-carpal joints of both forelegs were analysed for glycosaminoglycan (GAG) content. Immobilised non-weightbearing joints showed a significant loss of GAG compared with the other groups. More importantly, movement alone without weightbearing was sufficient to maintain GAG content, as was weightbearing without movement.

The effect of indomethacin on cartilage breakdown.

The effects of recombinant interleukin-1 alpha (rIL-1 alpha) and indomethacin on the glycosaminoglycan (GAG) content of rat femoral head cartilage (FHC) were studied in vitro. Net GAG loss was observed from cartilage cultured in the presence of indomethacin plus rIL-1 alpha. Indomethacin and rIL-1 alpha alone caused no net loss of GAG from cartilage unless the cartilage was cultured in the presence of fibroblasts.

Suppression of glycosaminoglycan synthesis by articular cartilage, but not of hyaluronic acid synthesis by synovium, after exposure to radiation.

We recently found that injection of 2 mCi of yttrium 90 (90Y; approximately 23,000 rads) into normal canine knees stimulated glycosaminoglycan (GAG) synthesis by femoral condylar cartilage. The present investigation was conducted to determine whether radiation affects cartilage metabolism directly. Rates of GAG synthesis and degradation in normal canine articular cartilage were studied following irradiation. Cultured synovium from the same knees was treated similarly, to determine the effects of irradiation on hyaluronic acid synthesis. Twenty-four hours after exposure to 1,000 rads, 10,000 rads, or 50,000 rads, 35S-GAG synthesis by the cartilage was 93%, 69%, and 37%, respectively, of that in control, nonirradiated cartilage. The effect was not rapidly reversible: 120 hours after exposure to 50,000 rads, GAG synthesis remained at only 28% of the control level. Autoradiography showed marked suppression of 35S uptake by chondrocytes after irradiation. Cartilage GAG degradation was also increased following irradiation: 4 hours and 8 hours after exposure to 50,000 rads, the cartilage GAG concentration was only 66% and 54%, respectively, of that at time 0, while corresponding values for control, nonirradiated cartilage were 90% and 87%. In contrast to its effects on cartilage GAG metabolism, radiation at these levels had no effect on synovial hyaluronic acid synthesis.

Moderate running exercise augments glycosaminoglycans and thickness of articular cartilage in the knee joint of young beagle dogs.

The local influences of physical exercise on thickness and glycosaminoglycan (GAG) content of canine articular cartilage were measured by microspectrophotometry of Safranin O- and periodic acid-Schiff (PAS)-stained tissue sections. Female Beagle dogs were housed in individual cages (bottom 0.9 x 1.2 m) and divided into runner (n = 6) and control (n = 8) groups. The training program started at the age of 15 weeks. During the subsequent 10 weeks, the dogs were accustomed to running on a treadmill inclined 15 degrees uphill. Thereafter, the dogs ran 1 h daily, 5 days a week, at a speed of 4 km/h for 15 weeks. At the age of 40 weeks, the dogs were killed, and the samples for histology were taken from 11 different anatomical locations of the right knee (stifle) joint. The thickness of the uncalcified cartilage increased 19-23% on the lateral condyle and patellar surface of the femur, whereas the enhancement was smaller in other parts of the trained cartilage. The calcified cartilage did not show thickness alterations. Total GAGs were augmented by 28% in the summits on the femoral condyles, more on the medial than lateral side. The increased GAGs appeared to be predominantly chondroitin sulphates and were localized in the intermediate, deep, and even in the calcified zones, whereas the superficial zone did not show changes. There was a concomitant increase of non-GAG oligosaccharides in the intermediate and deep zones, but not in the calcified cartilage.(ABSTRACT TRUNCATED AT 250 WORDS)

The sulphur content of chondrocyte nuclei.

The sulphur content as a measure of glycosaminoglycan content of growth plate cartilage was determined by energy dispersive x-ray analysis on fresh freeze dried unstained, unfixed ultra thin sections of rat growth plate. In the resting and proliferative zones, quantities of sulphur were found in the nuclei equal to that of the matrix. Less sulphur was present in the cytoplasm. In areas of cell degeneration nuclear and cytoplasmic content of sulphur fell to levels a fraction of that seen in the matrix. It was presumed that most of the sulphur was in glycosaminoglycans. Although glycosaminoglycans have been reported in small amounts in the nuclei of cells, no study of the glycosaminoglycan content of chondrocyte nuclei has been reported. The use of freeze dried unstained, unfixed sections presumably prevented the migration of sulphur and glycosaminoglycans from compartment to compartment.

Uridine diphosphate xylosyltransferase activity in cartilage from manganese-deficient chicks.

The glycosaminoglycan content of cartilage is decreased in manganese deficiency in the chick (perosis). The activity of xylosyltransferase, the first enzyme in the biosynthetic pathway of sulphated glycosaminoglycans, was studied in the epiphysial cartilage of 4-week-old chicks which had been maintained since hatching on a manganese-deficient diet. Enzymic activity was measured by the incorporation of [14C]xylose from UDP-[14C]xylose into trichloroacetic acid precipitates. Optimal conditions for the xylosyltransferase assay were established and shown to be the same for both control and manganese-deficient cartilage. Assay of the enzyme by using an exogenous xylose acceptor showed no difference in xylosyltransferase activity between control and manganese-deficient tissue. Further, the extent of xylose incorporation was greater in manganese-deficient than in control cartilage preparations, suggesting an increase in xylose-acceptor sites on the endogenous acceptor protein in the deficient cartilage. 35S turnover in the manganese-deficient cartilage was also increased. The data suggest that the decreased glycosaminoglycan content in manganese-deficient cartilage is due to decreased xylosylation of the acceptor protein plus increased degradation of glycosaminoglycan.

The distribution of serum albumin in human normal and degenerate articular cartilage

A method for studying the distribution of a high molecular weight solute (serum albumin) between physiological saline and human articular cartilage is described. Samples of normal and fibrillated articular cartilage from both femoral condyles and femoral heads have been studied. Limited studies have also been performed where the glycosaminoglycan content of normal cartilage has been reduced by chemical or enzymatic methods. With naturally occuring cartilage large a wide range of partition coefficients (0.3 to less than 0.002) was obtained. The partition coefficients are very dependent upon proteoglycan concentration, with the partitiion coefficient decreasing with increasing fixed charge density. An attempt is made to interpret the observed partitioning in terms of the steric exclusion by the proteoglycans.

The correlation of fixed negative charge with glycosaminoglycan content of human articular cartilage

A physical method is described for measuring the concentration of fixed negatively charged groups in articular cartilage. Comparison is made with values of fixed charged density derived from chemical analysis of hexuronic acid and total hexosamine contents. The mean deviation between values derived from the two methods was 10%. This study was carried out on successive tangentially cut slices of human articular cartilage from the femoral condyle. The following observations were made. The fixed charge density increased with depth from the articular surface, as did the uronic acid and total hexosamine contents. In the 25–60 age group neither the hexuronic acid nor the total hexosamine contents showed any correlation with the age of the subject. However, there was considerable local variation and variation between individuals.