Factors modifying collagen catabolism in patients with ankylosing spondylitis.

OBJECTIVE: We quantified the total excretion of the collagen crosslinks (CL) pyridinoline (PYD) and deoxypyridinoline (DPD) in 108 ankylosing spondylitis (AS) patients (29 f, 79 m) in correlation to different characteristics of disease to evaluate different mechanism contributing to development of osteoporosis in AS. METHODS: PYD and DPD were measured by HPLC. RESULTS: AS patients show a highly significant positive correlation between PYD and inflammatory activity. In cases involving peripheral joints, significantly higher CL levels in urine were found. Patients with syndesmophytes excreted significantly more CL vs. those without. In the more advanced stages of sacroiliitis (stage III and IV), CL levels tended to be higher. Among those patients treated with NSAIDs, a tendency to decreased levels of DPD and consecutive raised levels of the quotient PYD/DPD were observed. No significant correlation was found between restricted spine mobility or duration of disease and amount of excreted CL. CONCLUSIONS: Our investigations show that the inflammatory process, the involvement of the peripheral joints, the presence of syndesmophytes and the stage of sacroiliitis all have an influence on the extent of collagen degradation in AS patients. NSAIDs do not increase but appear to reduce collagen I catabolism.

[Particular features of steroid-induced osteoporosis]. / Besonderheiten der steroidinduzierten Osteoporose.

Glucocorticoid-induced osteoporosis (GIOP) is characterized by disturbed bone remodelling with consequent reduced bone mass and abnormally low quality of the bone tissue, resulting in an elevated risk of fracture. Glucocorticoids (GC) inhibit processes of bone formation and accelerate bone degradation, all of which must be taken into account especially in the case of long-term treatment with GC. Appropriate diagnostic procedures must be implemented early in the treatment and throughout the course, as must any preventive (improvement of general condition, calcium, vitamin D) and curative treatment required. When indications are carefully observed and the dosage is constantly checked and adjusted as needed, however, GC are not only helpful and beneficial in the treatment of the basic illnesses they are prescribed for, but on balance can even have a positive effect on bone in phases of high inflammatory activity.

Anabolic and catabolic function of chondrocyte ex vivo is reflected by the metabolic processing of type II collagen.

OBJECTIVE: The aim of the present study was to investigate collagen metabolism after anabolic and catabolic stimulation of chondrocytes ex vivo. DESIGN: Metabolic activities in ex vivo bovine cartilage explants were stimulated with insulin-like growth factor I (IGF-I) or a combination of tumor necrosis factor alpha (TNFalpha) and oncostatin M (OSM). Supernatants were assessed for changes in biochemical markers, N-terminal propeptide of type II (PIINP) collagen and fragments of C-telopeptide of type II collagen (CTX-II). Matrix metalloproteinases (MMP) were added to metabolic inactivated cartilage and evaluated by the two biochemical markers for formation or degradation, respectively. Finally, urinary CTX-II and PIINP were evaluated for assessment of type II collagen turnover in patients with rheumatoid arthritis (RA). RESULTS: In the bovine articular cartilage explants, IGF-I induced an increase in PIINP level up to 4.8+/-1.1[ng/ml]/mg cartilage whereas CTX-II remained below 0.1+/-0.1[ng/ml]/mg cartilage. In the catabolic stimulated explants both PIINP and CTX-II were released to the supernatant, reaching concentrations of 9.0+/-1.4 and 9.1+/-2.2[ng/ml]/mg cartilage, respectively. RA patients had significantly lower serum concentrations of PIINP (3.4+/-3.7 ng/ml) compared with those healthy individuals (18.7+/-12.41 ng/ml, P<0.001). In contrast, RA patients had significantly higher urinary CTX-II (0.8+/-0.8 mg/mmol) compared to the healthy controls (0.1+/-0.08 mg/mmol, P=0.004). CONCLUSIONS: This study is the first to demonstrate that precursors and degradation products of type II collagen released into the supernatant can effectively reflect the anabolic and catabolic activities of stimulated cartilage explants.

Detection of elevated N epsilon-carboxymethyllysine levels in muscular tissue and in serum of patients with fibromyalgia.

OBJECTIVES: To compare levels of the advanced glycation end product (AGE) N(epsilon)-carboxymethyllysine (CML) present in the muscle tissue and in the serum of patients with fibromyalgia (FM) vs. healthy controls. METHODS: The serum levels of CML were measured in 41 patients with FM and 81 healthy controls. The presence of CML, nuclear factor kappa B (NF-kappaB), the AGE receptor (RAGE), collagen types I, II, VI, and CD68-positive monocytes/macrophages in muscle tissue of 14 patients with FM was investigated by immunohistochemistry. RESULTS: Patients with FM showed significantly increased serum levels of CML in comparison to healthy controls. The immunohistochemical investigation revealed a stronger staining for CML and NF-kappaB and more CD68-positive monocytes/macrophages in the muscle of FM patients. The collagens and CML were co-localized, suggesting that the AGE modifications were related to collagen. RAGE was absent in controls but a faint and patchy staining was seen in FM. CONCLUSIONS: In the interstitial connective tissue of fibromyalgic muscles we found a more intensive staining of the AGE CML, activated NF-kappaB, and also higher CML levels in the serum of these patients compared to the controls. RAGE was only present in FM muscle. AGE modification of proteins causes reduced solubility and high resistance to proteolytic digestion of the altered proteins (e.g. AGE-modified collagens). AGEs can stimulate different types of cells by activation of the transcription factor NF-kappaB, mediated by specific receptors of AGEs (e.g. RAGE) on the cell surface. Both mechanisms may contribute to the development, perpetuation, and spreading of pain characteristic in FM patients.

Evaluation of free and peptide bound collagen crosslink excretion in different skeletal diseases.

OBJECTIVE: To investigate urinary fractions of free and peptide forms of collagen crosslinks in patients with rheumatoid arthritis (n=50), osteoarthrosis (n=38), psoriatic arthritis (n=38) and in healthy volunteers (33 adults, 17 children). METHODS: Pyridinoline (PYD) and deoxypyridinoline (DPD) were measured by high performance liquid chromatography. RESULTS: In rheumatoid arthritis (RA) all fractions of PYD and DPD were significantly raised compared with osteoarthritis, psoriatic arthritis, and healthy controls. PYD and DPD correlated with disease activity in RA. In RA the collagen degradation resulted in primarily peptide bound forms. CONCLUSION: The correlation between total peptide bound or free collagen crosslinks in different chronic joint diseases varies; however, this variation does not allow for a reliable differentiation between inflammatory and degenerative joint diseases.