Comparison of urinary glycosaminoglycan excretion in rheumatoid arthritis, osteoarthritis, myocardial infarction, and controls

Proteoglycan metabolism, cell death and Kashin-Beck disease

Kashin-Beck Disease (KBD) is an endemic, chronic and degenerative osteoarthropathy principally occurring in children. The characteristic pathological change of KBD is chondrocyte necrosis in hyaline articular cartilage. Proteoglycans are one of the major components in the extracellular matrix of articular cartilage, and disrupted proteoglycan metabolism and loss of proteoglycans in articular cartilage from KBD patients has been observed. In this mini-review, we discuss the close relationship between chondrocyte death including necrosis and loss of proteoglycan, and its potential mechanism during KBD onset and development, which may provide new clues for KBD research.

Increased excretions of glycosaminoglycans and heparan sulfate in lupus nephritis and rheumatoid arthritis

Urinary glycosaminoglycans (GAG) and heparan sulfate (HS) are considered to be markers of early renal involvement. This study was undertaken to demonstrate their excretion patterns in rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) with and without arthritis. Serum creatinine and urinary GAG, HS, microalbumin, and creatinine measurements were made in 51 biopsy-proven lupus nephritis (LN) cases, 12 RA patients, and 21 healthy controls. Urinary GAG and HS levels were higher in the LN and RA groups than in controls. Heparan sulfate excretions and SLE disease activity index (SLEDAI) scores were no different between SLE patients with classes 1 and 2 (group A) and those with classes 3, 4, and 5 (group B) renal involvement. However, GAG and microalbumin excretions were significantly high in the latter. There were no differences in GAG and HS excretions between normoalbuminuric, microalbuminuric, and macroproteinuric SLE patients or between those with and without arthritis. In conclusion, urinary GAG and HS, being unrelated to the presence of arthritis, are independent markers of LN. Extrarenal causes or subclinical renal involvement may be responsible in RA due to their increased excretion in these patients.

Estimating bone change in patients with severe disability

To evaluate bone change in severely disabled patients, bone density was assessed on X-ray pictures by the microdensitometry (MD) method, and urinary hydroxyproline (U-HYP), urinary glycosaminoglycans (U-GAG) serum calcium (S-Ca) and serum alkaline phosphatase (S-AP) were assessed in 43 patients (mean age 16 years) at the National Sanatrium Ehime Hospital. On division of the severity of bone change into grades 0 to 3 using the MD method. U-HYP was found to be significantly higher in grades 2 and 3 than in controls. Tendencies were similar for U-GAG and S-AP. U-HYP in immobile patients was significantly higher than in mobile patients. Immobilisation was one of the most important contributors to the development of bone change and results obtained using the MD method, U-HYP and U-GAG were valuable-indices of the bone change in severely disabled patients.

Markers of bone and collagen breakdown in early inflammatory arthritis

Inflammatory arthritis has the potential to cause irreversible erosive damage to cartilage and bone. This may occur very early in the course of the disease. At present it is not possible at diagnosis to identify those patients who will develop erosive damage. If this were possible, it would enable aggressive therapy to be targeted to those patients at greatest risk. There is therefore a need for sensitive markers to detect and quantify joint damage at as early a stage as possible. In this chapter we review potential biochemical markers of such damage and assess their clinical usefulness.

Cartilage proteoglycans in synovial fluid and serum in patients with inflammatory joint disease. Relation to systemic treatment

Proteoglycan concentrations in knee joint synovial fluid and in serum from patients with various inflammatory arthritides were studied using an enzyme-linked immunosorbent assay. Patients with reactive arthritis, calcium pyrophosphate arthropathy, and juvenile rheumatoid arthritis (age less than or equal to 20 years) had the highest synovial fluid concentrations. These values differed significantly (P less than 0.001) from those in patients with rheumatoid arthritis, psoriatic arthropathy, and chronic HLA-B27-associated arthropathy. Rheumatoid arthritis patients receiving low-dose prednisolone treatment had higher synovial fluid (P = 0.006) and serum (P less than 0.001) proteoglycan concentrations than did those taking nonsteroidal antiinflammatory drugs or slow-acting antirheumatic drugs. Serum proteoglycan concentrations were near the detection limits, and did not correlate with levels found in paired samples of knee joint synovial fluid. Patients with calcium pyrophosphate arthropathy had the highest mean serum level of proteoglycan. This assay of proteoglycan antigens is a useful tool in the study of proteoglycan metabolism in patients with joint disease. With its use, differences between disease groups and effects of therapy can be distinguished.

Extracellular mammalian polysaccharides: glycosaminoglycans and proteoglycans

This review of the mammalian extracellular matrix polysaccharides covered the glycosaminoglycans (GAGs) and their association into proteoglycans. As they necessarily pertain to the chromatographic and electrophoretic separations of these molecules, the structural features of the five principal GAGs were briefly reviewed. Much of the current structural work as well as the separation technology has been concerned with the sulfation state and copolymeric sequences of the individual classes of GAGs. The separation methods discussed included electrophoresis by agarose, acrylamide and cellulose acetate, high-performance liquid chromatography (HPLC), ion-exchange, gel permeation and biospecific affinity methods. Since detection systems are an integral part of chemical separation technology, current thoughts about the best methods to assay GAGs or detect column fractions were discussed. These included polysaccharide-specific detection systems such as Alcian blue dye, 1,9-dimethylmethylene blue, bovine serum albumin-Coomassie blue, as well as non-specific carbohydrate detection systems such as the carbazole or indole hydrochloride methods. Instrumentation used in the detection of chromatography fractions for these molecules was discussed, since the usual ultraviolet detector, standard with HPLC equipment, is often unsatisfactory. The most sensitive specific detection method for GAGs is the use of monoclonal antibodies, which are only now becoming commercially available. The use of these antibodies, combined with HPLC separation, appears to be the best available biochemical technology for studying the extracellular matrix polysaccharides. Finally, the association between proteoglycans, GAGs and mammalian disease processes was reviewed, emphasizing mucopolysaccharidoses and arthritis. The early detection of both of these diseases is desired for effective counselling and treatment. Many of the methods discussed here have been applied, but others are yet to be tried in efforts to further that goal.