Changes in chondroitin sulphate structure induced by joint disease

Spinal deformity in aged zebrafish is accompanied by degenerative changes to their vertebrae that resemble osteoarthritis

Age-related degenerative changes within the vertebral column are a significant cause of morbidity with considerable socio-economic impact worldwide. An improved understanding of these changes through the development of experimental models may lead to improvements in existing clinical treatment options. The zebrafish is a well-established model for the study of skeletogenesis with significant potential in gerontological research. With advancing age, zebrafish frequently develop gross deformities of their vertebral column, previously ascribed to reduced trunk muscle tone. In this study, we assess degenerative changes specifically within the bone and cartilage of the vertebral column of zebrafish at 1, 2 and 3-years of age. We show increased frequency and severity of spinal deformities/curvatures with age. Underlying the most severe phenotypes are partial or complete vertebral dislocations and focal thickening of the vertebral bone at the joint margins. MicroCT examination demonstrates small defects, fractures and morphological evidence suggestive of bone erosion and remodeling (i.e. osteophytes) within the vertebrae during aging, but no significant change in bone density. Light and electron microscopic examination reveal striking age-related changes in cell morphology, suggestive of chondroptosis, and tissue remodelling of the vertebral cartilage, particularly within the pericellular micro-environment. Glycosaminoglycan analysis of the vertebral column by HPLC demonstrates a consistent, age-related increase in the yield of total chondroitin sulfate disaccharide, but no change in sulfation pattern, supported by immunohistochemical analysis. Immunohistochemistry strongly identifies all three chondroitin/dermatan sulphate isoforms (C-0-S, C-4-S/DS and C-6-S) within the vertebral cartilage, particularly within the pericellular micro-environment. In contrast, keratan sulfate immunolocalises specifically with the notochordal tissue of the intervertebral disc, and its labelling diminishes with age. In summary, these observations raise the prospect that zebrafish, in addition to modelling skeletal development, may have utility in modelling age-related degenerative changes that affect the skeleton during senescence.

Solid phase assays in glycoconjugate research: applications to the analysis of proteoglycans, glycosaminoglycans and metalloproteinases

Glycoconjugates are a class of macromolecules consisting of different constituents, one of which is sugar moieties. Glycoconjugates comprise the majority of tissue constituents, both intracellular and extracellular. Extracellular glycoconjugates (glycoproteins and proteoglycans) participate in a wide variety of interactions, through which they maintain tissue integrity. Therefore, their analysis or the study of their possible interactions would give evidence for the state of tissues. Since the amounts of some of the extracellular glycoconjugates are usually low or the amounts of tissue to be examined come from biopsies, specific analytical systems are developed for their study, the most familiar being solid phase assays, which have the advantages of analysis of multiple samples on the same time, cheap instrumentation and high specificity.

Significance of chondroitin sulfate isomers in the synovial fluid of osteoarthritis patients

To test whether chondroitin sulfate (CS) isomers in synovial fluid are related to the radiographic severity of osteoarthritis (OA) and the age and sex, we investigated the concentrations of chondroitin 6-sulfate (C6S) and chondroitin 4-sulfate (C4S) in patients with OA of the knee joint and age-matched healthy controls. Synovial fluid was obtained from 133 patients with OA of the knee and 27 volunteers (controls). Twenty-seven patients were radiographically classified as grade 1, 59 as grade 2, 34 as grade 3, and 13 as grade 4 according to a modified version of the Kellgren and Lawrence scale. Compared with findings in the controls, values for the concentrations of C6S and C4S, and the C6 : C4S ratio, were significantly higher in the grade 1 patients, whereas in grade 3 and 4 patients, the C6S concentration and the C6 : C4S ratio were lower. There was an obvious sex difference, and all values for the women were significantly lower than those for the men in both the control and the patient groups. In the control group, multiple regression analysis showed a moderate inverse correlation between age and all three of the above biochemical variables, and sex was moderately associated with the C6S concentration and the C6S : C4S ratio. In the patient group, age and sex showed a poor correlation with any of the three variables. However, the radiographic severity of OA showed a relatively strong inverse correlation with the C6S concentration and the C6S : C4S ratio, and a weak inverse correlation with the C4S concentration.

Quantitation of chondroitin-sulfates, disaccharides and hyaluronan in normal, early and advanced osteoarthritic sheep temporomandibular joints

OBJECTIVE

To determine the relationship between synovial fluid, chondroitin sulfate disaccharide and hyaluronic acid to differing degrees of experimental temporomandibular joint (TMJ) osteoarthritis (OA).

DESIGN

Twenty-four merino sheep were divided into three groups and had different TMJ surgical procedures to produce OA. Group I; control (six sheep), Group II; disc perforation (nine sheep) and Group III; disc perforation and articular damage (nine sheep). Synovial fluid was collected initially and at sacrifice at 3 months. Chondroitin 4-sulfate, chondroitin 6-sulfate and hyaluronic acid were measured and correlated to the OA histologic score.

RESULTS

The chondroitin-sulfate levels were significantly increased (Group I to Group II P< 0.001; Group I to Group III P< 0.001), the hyaluronic acid levels decreased (Group I to Group II P< 0.01; Group I to Group III P< 0.01) with the increasing OA score.

CONCLUSION

Chondroitin-sulfate and hyaluronic acid show a correlation with surgically created TMJ osteoarthritis in sheep model.

Serum and synovial fluid levels of chondroitin sulfate in patients with osteoarthritis of the knee joint

We measured serum and synovial fluid levels of chondroitin sulfate (CS) in patients with osteoarthritis (OA) of the knee joint to clarify whether CS levels differ in various stages of OA, and whether measurement of CS levels is useful in evaluating the pathology of OA. The study population was 117 OA patients and 23 healthy young volunteers. Synovial fluid was obtained from 69 of 117 OA patients. The mean serum level of C4S in all of the OA patients was significantly higher than that in the controls (p< 0.05). However, there was little difference between respective OA stages. A small amount of serum C6S (0.2 to 0.6 nmol/ml) was detected in 31.6% of the OA patients and in 26.1%of the control subjects. The mean serum C0S level in all OA patients was significantly higher than that in the controls (p< 0.01). However no significant difference was found between respective OA stages. As for synovial fluid CS, the C4S level in the early stage of OA tended to be higher than that in the advanced stage. C6S levels showed a markedly decreasing trend with advancing OA stage. C0S was not detected in synovial fluid. The present study demonstrated that serum levels of C4S and C0S in OA patients are elevated compared with normal subjects, and that synovial fluid levels of C4S and C6S may provide useful in assessing the pathology of OA.