[Urological comorbidities in patients with rheumatoid arthritis : literature review]. / Urologische Begleiterkrankungen bei Patienten mit rheumatoider Arthritis : Literaturübersicht.

Patients with rheumatoid arthritis (RA) have an increased risk of urolithiasis which is further negatively impacted by a reduced bone density. Interstitial cystitis also tends to occur more often in patients with rheumatic diseases. The high incidence of bacterial urogenital infections is influenced by the use of immunomodulating drugs. Many RA patients have to undergo numerous tests until a diagnosis is reached and are then treated as outpatients on a tightly controlled schedule. Despite a closely controlled rheumatological follow-up, urological screening and determination of a baseline prostate-specific antigen (PSA) value (in men over 45 years old) should not be neglected. In patients with an increased risk of renal and bladder neoplasms or when such a diagnosis is known, the benefit of long-term use of high doses of non-steroidal anti-inflammatory drugs (NSAID, aspirin type) should be carefully weighed up with a risk profile and after specialist urological assessment. Patients who suffer from sexual dysfunction due to physical limitations and prolonged medical therapy should undergo urological and gynecological assessment to exclude contributing causes. The use of aphrodisiacs and erection-enhancing drugs (e.g. PDE5 inhibitors, local injection with prostaglandins and vacuum therapy) require prior approval by a medical specialist and also cardiovascular stability. Acute urinary retention is more common in chronic inflammatory musculoskeletal diseases.

[Autoimmune pancreatitis associated with rheumatoid arthritis: successful combination therapy with steroids and methotrexate]. / Autoimmunpankreatitis assoziiert mit rheumatoider Arthritis. Erfolgreiche Kombinationstherapie mit Steroiden und Methotrexat.

UNLABELLED: MEDICAL HISTORY AND CLINICAL FINDINGS: A 70-year-old female patient suffered from steatorrhea and upper abdominal discomfort for 8 weeks combined with new onset of arthralgia in both hands. Additionally she reported elevated fasting blood glucose levels. The physical examination was without pathological findings except for mild upper abdominal pressure pain. INVESTIGATIONS: Imaging studies, including MRI and ultrasound examinations showed diffuse pancreatic enlargement without peripancreatic vessel involvement. Serological examinations showed elevated Cancer Associated Antigen 19 - 9 (1289 U/ml) and hyperglobulinemia with an IgG level of 170 mg/dl. The inflammatory markers were within normal ranges other than a slightly elevated erythrocyte sedimentation rate (35mm/1 h). Subsequent pancreatic biopsy showed lymphoplasmocellular, neutrophile and eosinophile granulocyte infiltration causing damage of the acinar pancreatic cells, typical for autoimmune pancreatitis (AIP). Magnetic resonance imaging (MRI) confirmed arthritis of both hands. TREATMENT AND COURSE: Medical treatment was started with oral prednisolone (50 mg/day) for one week, tapered to 25 mg/day for another 2 weeks, followed by dose reductions of 5 mg/day every 2 weeks with a final maintenance dose of 5 mg/day for 8 months. After the first week of steroid therapy methotrexate (MTX) was started with an initial dose of 10 mg/week. Dose was raised until a final dosage of 30 mg/week. After 8 months without relapse, the maintenance therapy was reduced to 20 mg/week MTX and corticosteroids were stopped. CONCLUSION: With this treatment regimen the patient has showed complete remission of AIP and arthritis for 36 months. MTX may be successful as an initial basic treatment to reach better control of autoimmune-related extrapancreatic manifestations.

Stimulatory effects of distinct members of the bone morphogenetic protein family on ligament fibroblasts.

OBJECTIVE: To investigate effects of cartilage derived morphogenetic protein-1 and -2 (CDMP-1, CDMP-2), bone morphogenetic protein (BMP)-7 and BMP-6 on metabolism of ligament fibroblasts and their osteogenic or chondrogenic differentiation potential. METHODS: Ligament fibroblasts were obtained from 3 month old calves, plated as monolayers or micromass cultures, and incubated with or without CDMP-1, CDMP-2, BMP-7, and BMP-6. Expression of the indicated growth factors was assessed by RT-PCR and western immunoblotting. The presence of their respective type I and II receptors, and lineage related markers, was investigated in stimulated and unstimulated cells by RT-PCR and northern blotting. Biosynthesis of matrix proteoglycans was assessed by [(35)S]sulphate incorporation in monolayers. Alcian blue and toluidine blue staining was done in micromass cultures. RESULTS: CDMP-1, CDMP-2, BMP-7, and BMP-6 were detected on mRNA and on the protein level. Type I and II receptors were endogenously expressed in unstimulated ligament fibroblasts. The growth factors significantly stimulated total proteoglycan synthesis as assessed by [(35)S]sulphate incorporation. Toluidine blue staining showed cartilage-specific metachromasia in the growth factor treated micromass cultures. Transcription analysis of stimulated ligament fibroblasts demonstrated coexpression of chondrocyte markers but no up regulation of osteogenic markers. CONCLUSION: CDMP-1, CDMP-2, BMP-7, and BMP-6 and their receptors were expressed in ligament tissue. These growth factors induced matrix synthesis in fibroblasts derived from bovine ligament. The preferential expression of cartilage markers in vitro suggests that CDMP-1, CDMP-2, BMP-7, and BMP-6 have the potential to induce differentiation towards a chondrogenic phenotype in ligament fibroblasts. Thus, fibroblasts from ligaments may serve as a source for chondrogenesis and tissue repair.

Decrease of proteinuria in a patient with adult-onset Still's disease and glomerulonephritis after anti-TNFalpha therapy.

We report the case of a 41-year-old man diagnosed with Still's disease. Multiple disease-modifying anti-rheumatic drug (DMARD) therapies failed to induce disease remission or to prevent progressive joint destruction. The man presented with active arthritis and classical Still's rash accompanied by fever. Anti-tumour necrosis factor-alpha (TNFalpha) therapy was planned but during the medical check-up prior to the biological therapy, renal insufficiency with marked proteinuria (PU) was discovered. With PU of 912 mg/24 h a renal biopsy was performed and a histopathological evaluation revealed the diagnosis of a residual mesangio-proliferative immunocomplex-based glomerulonephritis (GN). After excluding contraindications, infliximab therapy was initiated and a good response of the arthritis was documented after 6 weeks. A significant decrease in PU (279 mg/24 h) was noted after the third infliximab infusion. Because of an allergic reaction during the fifth dose, the infliximab was discontinued. During the time frame without anti-TNFalpha therapy, active joint disease reoccurred and the proteinuria increased significantly. Because of the active disease entanercept therapy was initiated. The arthritis diminished and the PU was reduced markedly within 4 weeks. In the follow-up period of 12 months a good response to therapy was sustained. As described by other investigators, the joint disease showed a rapid and sustained response to anti-TNFalpha therapy. The decrease in proteinuria during biological therapy was notable. It was concluded that the significant decrease in PU in this patient was achieved by eliminating the inflammatory activity of the underlying kidney disease.

Chondrocyte number and proteoglycan synthesis in the aging and osteoarthritic human articular cartilage.

OBJECTIVE: To correlate the number of chondrocytes in healthy and osteoarthritic human articular cartilage with age, and to evaluate the influence of donor age on total proteoglycan synthesis. METHODS: Chondrocytes were isolated from human articular cartilage derived from hip joints with and without osteoarthritic lesions. The cell number was normalised to cartilage sample wet weight. In addition, the influence of age on chondrocyte numbers was assessed histomorphometrically. Chondrocytes were grown as monolayer cultures for seven days in a chemically defined serum-free basal medium. Total proteoglycan synthesis was measured by [(35)S]sulphate incorporation into newly synthesised macromolecules. RESULTS: Chondrocyte numbers in healthy cartilage decreased significantly with advancing age (r = -0.69, p<0.0001). In contrast to healthy specimens, chondrocyte numbers were decreased in osteoarthritic cartilage irrespective of and unrelated to age, and differed markedly, by an average of 38%, from the cell numbers found in healthy individuals (p<0.0001). Regarding synthesis of matrix macromolecules, no dependence on patients' age, either in healthy or in osteoarthritic specimens, could be observed. CONCLUSIONS: Under the experimental conditions employed, chondrocytes from healthy and osteoarthritic joints synthesised comparable amounts of cartilage macromolecules, independent of age or underlying osteoarthritic disease. Thus the decrease in chondrocyte number in aging and osteoarthritic joints could be a crucial factor in limiting tissue replenishment.

Expression of bone morphogenetic protein 6 in healthy and osteoarthritic human articular chondrocytes and stimulation of matrix synthesis in vitro.

OBJECTIVE: To elucidate the role of bone morphogenetic protein 6 (BMP-6) in human articular cartilage, we investigated whether BMP-6 is expressed in adult human articular chondrocytes and analyzed the potential stimulatory effects of BMP-6 on these cells. In addition, we investigated whether osteoarthritic (OA) and normal cartilage chondrocytes behave differently. METHODS: Endogenous expression of the BMP-6 gene was examined by reverse transcription-polymerase chain reaction. BMP-6 protein was detected by Western immunoblotting. Chondrocytes were grown as monolayer cultures for 7 days in a chemically defined serum-free medium, in the absence or presence of recombinant BMP-6. Proteoglycan (PG) synthesis was measured by (35)S-sulfate incorporation into newly synthesized macromolecules. Cell proliferation was assessed by (3)H-thymidine incorporation. RESULTS: BMP-6 was expressed in both healthy and OA chondrocytes at the messenger RNA and protein levels. Total PG synthesis was significantly increased after BMP-6 stimulation of healthy (mean +/- SEM 191 +/- 11%; P < 0.001) and OA (150 +/- 25%; P < 0.03) chondrocyte cultures. A direct comparison between healthy and OA samples revealed no significant difference. The proliferation rates of normal and OA chondrocytes were not affected by BMP-6 treatment. CONCLUSION: BMP-6 is endogenously expressed in chondrocytes obtained from OA and normal adult human articular cartilage. Furthermore, BMP-6 has the potential to stimulate total PG synthesis in human articular chondrocytes derived from normal as well as OA joints. We conclude that the presence of BMP-6 in adult human articular cartilage indicates a functional role for this growth factor in the maintenance of joint integrity.

Is pro-matrix metalloproteinase-3 a marker for posttraumatic cartilage degradation?

OBJECTIVE: Since the development of posttraumatic osteoarthritis (OA) is a relatively slow process, estimation of OA risk would be of value with regard to chondroprotective measures and medication. In this study we investigated the significance of pro-matrixmetalloproteinase-3 (proMMP-3) for this purpose. DESIGN: Synovial fluid (SF) and serum samples were collected from 259 patients of our trauma clinic at the time of arthroscopy. The extent of cartilage damage was assessed according to the Outerbridge-score. ProMMP-3 levels in SF and serum were determined by enzyme-linked immunosorbent assay (ELISA) using a monoclonal antibody. Additionally we determined SF and serum levels of total MMP-3 and COMP levels as well as TIMP-1 and -2 concentrations in 40 randomly selected patients by ELISA. RESULTS: Serum proMMP-3 levels of the total cohort were markedly increased compared to healthy controls (P<0.007). The comparison of serum and SF lavage proMMP-3 concentrations showed a significant correlation (r(s)=0.41, P<0.0001), however, only 26% of the investigated samples were increased above normal ranges. The grade of cartilage damage did not correlate with enzyme concentration neither in patients' serum nor in SF samples. ProMMP-3 SF concentration was increased early after trauma. Furthermore, proMMP-3 correlated significantly with total MMP-3 serum and SF levels as well as COMP SF levels. CONCLUSIONS: The measurement of proMMP-3 in serum or SF did not reflect the present cartilage damage and thus appears to have only minor potential for clinical use, but it should be considered for longitudinal studies, since it may reflect a risk for cartilage degradation in a subset of patients.

Cartilage-derived morphogenetic protein-1 and -2 are endogenously expressed in healthy and osteoarthritic human articular chondrocytes and stimulate matrix synthesis.

OBJECTIVE: We investigated whether chondrocytes derived from osteoarthritic cartilage may lose their responsiveness to cartilage-derived morphogenetic protein-1, -2 (CDMP-1, -2) and osteogenic protein-1 (OP-1) compared with healthy cells, thus leading to an impaired maintenance of matrix integrity. DESIGN: Chondrocytes were isolated from articular cartilage from patients with and without osteoarthritic lesions. Cells were grown as monolayer cultures for 7 days in a chemically defined serum-free basal medium (BM) in the presence of recombinant CDMP-1, -2, and OP-1. Glycosaminoglycan synthesis was measured by [35S]Sulfate incorporation into newly synthesized macromolecules. Cell proliferation was investigated by [3H]Thymidine incorporation. The endogenous gene expression of CDMPs/OP-1 and their respective type I and type II receptors was examined using RT-PCR. The presence of CDMP proteins in tissue and cultured cells was detected by Western immunoblots. RESULTS: mRNAs coding for CDMPs and their respective receptors are endogenously expressed not only in healthy, but also in osteoarthritic cartilage. CDMP proteins are present in both normal and osteoarthritic articular cartilage and cultured chondrocytes. CDMP-1, CDMP-2 and OP-1 markedly increased glycosaminoglycan synthesis in both healthy (P< 0.01) and osteoarthritic (P< 0.05) human articular chondrocytes. A comparison of the glycosaminoglycan biosynthetic activity between healthy and osteoarthritic samples revealed no detectable difference, neither in stimulated nor in unstimulated cultures. [(3)H]Thymidine incorporation showed that CDMPs/OP-1 did not affect cell proliferation in vitro. CONCLUSION: CDMPs and OP-1 exert their anabolic effects on both healthy and osteoarthritic chondrocytes indicating no loss in responsiveness to these growth factors in OA. The endogenous expression of CDMPs/OP-1 and their receptors suggest an important role in cartilage homeostasis.

[The effect of Condrosulf (sodium chondroitin sulfate) on proteoglycan synthesis by human osteoarthritic an bovine juvenile articular cartilage chondrocytes--an in vitro study]. / Der Einfluss von Condrosulf (Natriumchondroitinsulfat) auf die Proteoglykansynthese und Zellproliferation osteoarthrotischer humaner und juveniler boviner Gelenksknorpelzellen--eine In-vitro-Untersuchung.

BACKGROUND: Sodiumchondroitinsulfate, Condrosulf, is used in osteoarthritis therapy and belongs to the group of symptomatic slow-acting drugs for osteoarthritis. The aim of this study was to investigate the effects of Condrosulf on total proteoglycan synthesis and cell proliferation in human osteoarthritis and healthy juvenile bovine chondrocytes in vitro. METHODS: Chondrocytes were grown as monolayers and stimulated for 7 (human cartilage), or 4, 8 and 12 days (bovine cartilage) with different concentrations of Condrosulf (100 micrograms/ml, 500 micrograms/ml, 1000 micrograms/ml, 2500 micrograms/ml and 5000 micrograms/ml). Proteoglycan synthesis was measured by [35S]Sulfate incorporation. The cell proliferation rate was determined using a [3H]Thymidin assay. The expression of the cartilage markers aggrecan and collagen type II was assessed by Northern blot analysis. RESULTS: We show that the incubation with Condrosulf did not affect proteoglycan synthesis neither in osteoarthritis, nor in healthy chondrocytes under the present culture conditions. Cell proliferation rate was also not increased by Condrosulf stimulation. The results of the Northern blot assays demonstrated a dose-dependent down regulation of aggrecan expression on mRNA level. CONCLUSIONS: These data indicate a lack of direct anabolic effects of Condrosulf on the biosynthetic activity of cultured articular chondrocytes. The well known ease of clinical symptoms, such as pain or swelling under Condrosulf medication may be interpreted by an interaction with pro-inflammatory cytokines.

Effects of cartilage-derived morphogenetic proteins and osteogenic protein-1 on osteochondrogenic differentiation of periosteum-derived cells.

Localization studies and genetic evidence have implicated cartilage-derived morphogenetic proteins-1, -2 (CDMP-1 and CDMP-2), and osteogenic protein-1 (OP-1) in the osteochondrogenic differentiation of mesenchymal progenitor cells during embryonic development and in postnatal life. Based on their expression pattern and the evidence that periosteum contains mesenchymal cells in the cambium layer that can undergo bone and cartilage formation, we hypothesized that CDMPs and OP-1 may be involved in long bone development and fracture healing. To test this hypothesis, periosteum-derived cells from young calves were cultured as monolayers under serum-free conditions with and without the addition of recombinant CDMP-1, CDMP-2 and OP-1. Phenotypic analysis indicate that periosteum-derived cell populations prepared, expanded, and cultured under the conditions described below, constitutively express messenger RNAs for the bone markers osteocalcin, osteopontin and collagen type I, and the chondrogenic markers collagen type II and aggrecan as determined by RT-PCR. Moreover, histologic examinations showed positive staining for alcian blue and alkaline phosphatase (AP). Treatment of periosteum-derived cells with CDMPs and OP-1 resulted in a dose-dependent increase of cell proliferation; CDMP-2 was less active in this regard. Furthermore, all growth factors enhanced osteogenic differentiation as assessed by a time- and dose-dependent stimulation of AP activity and OP-1 increased messenger RNA expression for osteocalcin and collagen type I. We further examined the effects of CDMPs and OP-1 on chondrogenic differentiation of periosteum-derived cells. Both CDMPs and OP-1 stimulated (35)S-sulfate incorporation into newly synthesized macromolecules with OP-1 having a more pronounced stimulatory effect when compared with CDMP-1 and CDMP-2. Our results indicate that distinct members of the BMP-family increase the mitotic and metabolic activity of periosteum-derived cells. The enhancement of both the chondrogenic and osteogenic differentiation suggests that these growth factors might contribute to the local regulation of bone formation and fracture repair.

Stimulatory effects of cartilage-derived morphogenetic proteins 1 and 2 on osteogenic differentiation of bone marrow stromal cells.

Cartilage-derived morphogenetic proteins 1 and 2 (CDMP-1 and CDMP-2) are members of the bone morphogenetic protein (BMP) family which play an important role in embryonic skeletal development. Throughout adult life, bone marrow-derived precursor cells maintain their ability to differentiate into osteoblasts in response to local growth factors. This study examines the osteogenic potential of CDMP-1, CDMP-2, BMP-6 and osteogenic protein 1 (OP-1) in bone marrow stromal cells (BMSC) and investigates the endogenous expression of CDMPs/BMPs and their respective activin receptor-like kinase (ALK) receptors. A 4-day exposure of BMSC to CDMP-1, CDMP-2, BMP-6, and OP-1 under serum-free conditions stimulated the progression of the osteogenic lineage in a dose-dependent manner as evaluated by alkaline phosphatase activity and osteocalcin synthesis. In contrast to the BMPs, CDMP-1 and especially CDMP-2 were significantly less osteogenic, as confirmed by Northern blot analysis. Moreover, BMSC were shown to express endogenously CDMP-2, BMP-2 to -6 and ALK-1, -2, -3, -5 and -6. Phenotypic characterization of BMSC by RT-PCR showed transcripts of the fat marker adipsin and the prechondrocytic marker procollagen type IIA; however, we were unable to detect the mature cartilage markers, procollagen type IIB and aggrecan, even after growth factor treatment. Our data indicate that CDMP-1, CDMP-2, BMP-6 and OP-1 enhance the osteogenic phenotype in BMSC, with CDMPs being clearly less osteogenic than BMPs. The endogenous expression of a variety of CDMPs/BMPs and their respective ALK receptors, suggests a possible involvement of these growth factors in the osteogenic differentiation of bone marrow progenitor cells.

Early pulmonary involvement in ankylosing spondylitis: assessment with thin-section CT.

AIM: To determine the frequency and the distribution of early pulmonary lesions in patients with ankylosing spondylitis (AS) and a normal chest X-ray on thin-section CT and to correlate the CT findings with the results of pulmonary function tests and clinical data. MATERIALS AND METHODS: Twenty-five patients with clinically proven AS and no history of smoking underwent clinical examinations, pulmonary function tests (PFT), chest radiography, and thin-section CT. Four of 25 patients (16%), who had obvious signs on plain films suggestive of pre-existing disorders unrelated to AS were excluded. RESULTS: Fifteen of 21 patients (71%) had abnormalities on thin-section CT. The most frequent abnormalities were thickening of the interlobular septa in seven of 21 patients (33%), mild bronchial wall thickening in (6/21, 29%), pleural thickening and pleuropulmonary irregularities (both 29%) and linear septal thickening (6/21, 29%). In six patients there were no signs of pleuropulmonary involvement. Eight of 15 patients (53%) with abnormal and four of six patients (67%) with normal CT findings revealed mild restrictive lung function impairment. CONCLUSION: Patients with AS but a normal chest radiograph frequently have abnormalities on thin-section CT. As these abnormalities are usually subtle and their extent does not correlate with functional and clinical data, the overall routine impact of thin-section CT in the diagnosis of AS is limited.

Expression of adhesion molecules on synovial fluid and peripheral blood monocytes in patients with inflammatory joint disease and osteoarthritis.

OBJECTIVE: To determine the presence of adhesion molecules on monocytes/macrophages (Mphi) from peripheral blood (PB) and synovial fluid (SF) in patients with osteoarthritis (OA) and inflammatory joint diseases (rheumatoid (RA) and reactive arthritis (ReA)) in order to improve our understanding of the possible mechanisms underlying the inflammatory process. METHODS: Whole blood and SF cells were stained with monoclonal antibodies against CD11a (LFA-1), CD15 s (sialyl-Lewis X), CD44, CD54, VLA-4, and HLA-DR counterstained with anti-CD14 antibodies as a Mphi marker for dual fluorescence analysis by flowcytometry. RESULTS: On PB-Mphi, CD15s was markedly increased in both RA as well as ReA compared with OA. Furthermore, in the PB LFA-1, CD44, and HLA-DR showed a higher surface density on Mphi in ReA than in OA. Comparison between SF and PB showed significantly higher CD44 and CD54 expression on SF-Mphi. These molecules play an important part in lymphocyte-Mphi interaction. CONCLUSION: In PB from patients with inflammatory joint diseases, Mphi are activated, allowing recruitment into the synovial compartment. These disorders, in contrast with OA seem to be "systemic" in nature. Within the SF, different adhesion molecules are expressed on CD14(+) Mphi as compared with PB.

[Rheumatic diseases of the ankle joint and tarsus]. / Rheumatische Erkrankungen des Sprunggelenkes und der Fusswurzel.

Diseases of the hindfoot are associated with considerable functional impairment and therefore may hamper patients' movements during gait considerably. Because of biomechanical overload, articular structures, tendons and ligaments are prone to early degenerative changes during the course of rheumatic diseases as visible with plain film radiography, sonography (US), or magnetic resonance imaging (MRI). Findings may occur as arthritis of major joints or in the form of fibroostitis and bursitis of the os calcis. Despite the progressive course of rheumatic diseases and characteristic imaging findings, high variability of X-ray signs may occur. Plain film radiograms and high-resolution ultrasonography play a key role in imaging rheumatic diseases of the hindfoot. MRI supports imaging diagnosis in selected cases. The principal goals of diagnostic imaging are precise and reproducible documentation of morphologic abnormalities and differentiated analysis for planning proper conservative or surgical treatment.

Sucrose permeability as a marker for NSAID-induced gastroduodenal injury.

OBJECTIVE: To evaluate sucrose permeability as a non-invasive test for the monitoring of upper gastrointestinal mucosal damage (uGMD) in patients treated with NSAIDs. METHODS: 40 patients with non-inflammatory joint pain were enrolled in a prospective study. Before and after 14 days of ibuprofen treatment (3 x 400 mg/day), the rates of urinary sucrose excretion after an oral sucrose load were assessed. Individuals with increased sucrose permeability underwent endoscopy. RESULTS: 8 patients (20%) showed abnormal sucrose permeability before taking any NSAID. In 5/20 patients (25%) who completed 2 weeks of ibuprofen medication, sucrose excretion increased above the normal level. Endoscopic examination and biopsy revealed mild uGMD, but no ulceration in 8/11 (72%) patients with increased permeability to this marker. CONCLUSION: Sucrose permeability testing is a sensitive procedure for research protocols on NSAID-induced gastropathy. Since this test also seems to detect slight and clinically insignificant mucosal damage, however, its use in clinical decision-making regarding gastroprotective medication is limited.

Cartilage-derived morphogenetic proteins and osteogenic protein-1 differentially regulate osteogenesis.

Cartilage-derived morphogenetic proteins-1 and -2 (CDMP-1 and CDMP-2) are members of the bone morphogenetic protein (BMP) family, which play important roles in embryonic skeletal development. We studied the biological activities of recombinant CDMP-1 and CDMP-2 in chondrogenic and osteogenic differentiation and investigated their binding properties to type I and type II serine/threonine kinase receptors. In vivo, CDMP-1 and CDMP-2 were capable of inducing dose-dependently de novo cartilage and bone formation in an ectopic implantation assay. In vitro studies using primary chondrocyte cultures showed that both CDMP-1 and CDMP-2 stimulated equally de novo synthesis of proteoglycan aggrecan in a concentration-dependent manner. This activity was equipotent when compared with osteogenic protein-1 (OP-1). In contrast, CDMPs were less stimulatory than OP-1 in osteogenic differentiation as evaluated by alkaline phosphatase activity and expression levels of bone markers in ATDC5, ROB-C26, and MC3T3-E1 cells. CDMP-2 was the least osteogenic in these assays. Receptor binding studies of CDMP-1 and CDMP-2 revealed that both have affinity for the BMP receptor type IB (BMPR-IB) and BMPR-II, and weakly for BMPR-IA. Moreover, using a promoter/reporter construct, transcriptional activation signal was transduced by BMPR-IB in the presence of BMPR-II upon CDMP-1 and CDMP-2 binding. Our data show that distinct members of the BMP family differentially regulate the progression in the osteogenic lineage, and this may be due to their selective affinity for specific receptor complexes.

Presence of cartilage-derived morphogenetic proteins in articular cartilage and enhancement of matrix replacement in vitro.

OBJECTIVE: To investigate the effects of the cartilage-derived morphogenetic proteins (CDMPs) in an in vitro cartilage explant model that mimics the chondrocytic response to matrix depletion, and to demonstrate their presence in articular cartilage. METHODS: Adult bovine articular cartilage and postmortem specimens from adult human donors with and without osteoarthritic (OA) lesions were stained by immunohistochemistry using polyclonal antibodies specific for CDMP-1 and CDMP-2. Extracts of bovine articular cartilage were analyzed by Western blotting for the presence of the CDMPs. Bovine articular cartilage explants were depleted of their matrix by trypsin digestion, followed by a 7-day culture period in a chemically defined serum-free basal medium (BM), with or without recombinant CDMPs 1 and 2. The metabolic activity of chondrocytes was measured by 35S-sulfate incorporation into macromolecules. Newly synthesized proteoglycans (PGs) were analyzed using Sephacryl S-500 HR gel chromatography. The expression levels of the messenger RNA (mRNA) for chondrogenic markers were investigated by Northern analysis. RESULTS: CDMP-1 and CDMP-2 were detected in both bovine and human healthy and OA articular cartilage. Treatment of matrix-depleted cartilage explants with CDMPs 1 and 2 increased equally the incorporation of 35S-sulfate into PGs compared with tissue maintained in BM. Gel chromatography analysis indicated that aggrecan was the predominant PG species. Northern blot analysis showed that the expression of link protein, type II collagen, and aggrecan mRNA transcripts was not modulated by CDMP treatment. CONCLUSION: This study shows the presence of CDMP-1 and CDMP-2 in adult bovine and human articular cartilage. In addition, our in vitro data indicate that CDMPs 1 and 2 stimulate the metabolic activity of articular chondrocytes. Therefore, these signaling molecules may be contributing to the maintenance of the integrity of the joint surface.

Effects of ciprofloxacin and ofloxacin on adult human cartilage in vitro.

Chondrocyte toxicity and necrosis were seen with electron microscopy after incubation of human adult cartilage biopsy specimens in ciprofloxacin or ofloxacin. In vitro exposure of chondrocytes to fluoroquinolones did not affect apoptosis as determined by flow cytometry. While the immediate clinical significance of this finding remains unclear, the possibility of long-term cartilage damage after fluoroquinolone treatment cannot be excluded.