Stromelysin 1, neutrophil collagenase, and collagenase 3 do not play major roles in a model of chondrocyte mediated cartilage breakdown

Combining stretching and gallic acid to decrease inflammation indices and promote extracellular matrix production in osteoarthritic human articular chondrocytes

Osteoarthritis (OA) patients undergo cartilage degradation and experience painful joint swelling. OA symptoms are caused by inflammatory molecules and the upregulation of catabolic genes leading to the breakdown of cartilage extracellular matrix (ECM). Here, we investigate the effects of gallic acid (GA) and mechanical stretching on the expression of anabolic and catabolic genes and restoring ECM production by osteoarthritic human articular chondrocytes (hAChs) cultured in monolayers. hAChs were seeded onto conventional plates or silicone chambers with or without 100 μM GA. A 5% cyclic tensile strain (CTS) was applied to the silicone chambers and the deposition of collagen and glycosaminoglycan, and gene expressions of collagen types II (COL2A1), XI (COL11A2), I (COL1A1), and X (COL10A1), and matrix metalloproteinases (MMP-1 and MMP-13) as inflammation markers, were quantified. CTS and GA acted synergistically to promote the deposition of collagen and glycosaminoglycan in the ECM by 14- and 7-fold, respectively. Furthermore, the synergistic stimuli selectively upregulated the expression of cartilage-specific proteins, COL11A2 by 7-fold, and COL2A1 by 47-fold, and, in contrast, downregulated the expression of MMP-1 by 2.5-fold and MMP-13 by 125-fold. GA supplementation with CTS is a promising approach for restoring osteoarthritic hAChs ECM production ability making them suitable for complex tissue engineering applications.

Culture duration modulates collagen hydrolysate-induced tissue remodeling in chondrocyte-seeded agarose hydrogels

Media supplementation with collagen hydrolysate was hypothesized to increase the collagen content in engineered cartilage. By d28, hydrolysate at 0.5 mg/mL increased type II collagen content and 1 mg/mL increased mechanical properties, total collagen content, and type II collagen content over controls. By d42, however, controls possessed the highest GAG content and compressive Young's modulus. Real-time PCR found that 1 mg/mL increased type II collagen gene expression in d0 constructs, but increased MMP expression with no effect on type II collagen on d28. A 10 mg/mL concentration produced the lowest tissue properties, the lowest type II collagen gene expression on d0, and the highest MMP gene expression on d28. These results indicate that the duration of culture modulates the response of chondrocytes to collagen hydrolysate in 3D culture, transforming the response from positive to negative. Therefore, collagen hydrolysate as a media supplement is not a viable long-term method to improve the collagen content of engineered cartilage tissue.

Retinoic acid and oncostatin M combine to promote cartilage degradation via matrix metalloproteinase-13 expression in bovine but not human chondrocytes

OBJECTIVES

Retinoic acid (RetA) and oncostatin M (OSM) have both been shown to mediate potent effects with respect to extracellular matrix integrity. This study assesses the effects of a RetA + OSM combination on cartilage catabolism.

METHODS

Animal and human cartilage samples were used to assess the ability of RetA + OSM to promote the release of collagen and proteoglycan fragments, which was determined by measuring glycosaminoglycan and hydroxyproline, respectively. Total collagenolytic and tissue inhibitor of metalloproteinases (TIMP) inhibitory activities were determined by bioassay, whilst gene expression of matrix metalloproteinases (MMPs) and TIMP-1 were determined by northern blotting. Immunohistochemistry was used to assess the presence of MMP-1 and -13 in resorbing cartilage explants.

RESULTS

Both agents alone induced proteoglycan release from bovine cartilage, whilst RetA-induced collagen release was variable. Reproducible and synergistic collagenolysis was observed with RetA + OSM, which appeared to be due to MMP-13. Similar collagen release was observed from porcine cartilage. Conversely, no collagen release was seen with human articular cartilage. In primary human chondrocytes, RetA + OSM failed to induce MMP-1 or -13 but caused a significant increase in TIMP-1 expression.

CONCLUSIONS

These novel observations show that the combination of RetA + OSM has profound effects on cartilage matrix turnover, but these effects are species-specific. A better understanding of the mechanism by which this combination differentially regulates MMP and TIMP expression in human chondrocytes could provide valuable insight into new therapeutic strategies aimed at the prevention of cartilage destruction.

Autologous chondrocyte implantation (ACI) for aged patients: development of the proper cell expansion conditions for possible therapeutic applications

OBJECTIVE

Proliferation and chondrogenic commitment of cultured articular chondrocytes are impaired when cells derive from aged donors. In those subjects the feasibility of cell-based therapies for articular surface repair is reduced. Moreover, the use of serum as medium supplement elicits non-physiological responses in cultured chondrocytes. This study was therefore undertaken to identify the expansion culture conditions needed to sustain growth and chondrogenic commitment of chondrocytes harvested from aged human subjects.

DESIGN

Articular cartilage was obtained from aged (69-75 years) and from young adult subjects (27-35 years). Chondrocytes were isolated and cultured in serum-free (SF) or in serum-supplemented [fetal calf serum (FCS)] conditions. Chondrocytes were expanded in monolayer for five duplications and processed for RNA extraction and reverse transcriptase-polymerase chain reaction (RT-PCR) analysis. The differentiation potential was assessed by micromass pellet cultures before and after expansion in either culture medium, or after a prolonged exposure to serum followed by a period in SF condition.

RESULTS

Only SF-cultured chondrocytes reached five duplications within 25-35 days, maintaining the expression of some chondrogenic markers and without altering the levels of active matrix metalloproteinase 3 (MMP-3). Only the pellets derived from SF-expanded cultures positively stained for cartilage matrix deposition. On the contrary, exposure to serum diminished the proliferation capacities, abolished the differentiation potential in the same cells and elicited transcription of the MMP-3 gene. Shifting culture conditions from FCS to SF resumed growth rates but proper extracellular matrix deposition was only partially restored.

CONCLUSIONS

The SF conditions have proven valuable to prime cell proliferation and to sustain proper commitment in chondrocytes from aged patients. This culturing approach may represent a therapeutic chance extendable to a range of patients normally excluded from clinical protocols based on autologous chondrocyte implantation (ACI).

Human nasal cartilage responds to oncostatin M in combination with interleukin 1 or tumour necrosis factor alpha by the release of collagen fragments via collagenases

BACKGROUND

The synergistic degradation of cartilage by oncostatin M (OSM) in combination with either interleukin 1 (IL1) or tumour necrosis factor alpha (TNFalpha) has been previously demonstrated using bovine nasal cartilage (BNC).

OBJECTIVES

(a) To investigate if human nasal cartilage (HNC) responds in the same way as BNC to these cytokine combinations, particularly in collagen degradation. (b) To compare the response of human nasal and articular cartilages.

METHODS

Collagen release was assessed by measuring the hydroxyproline content of culture supernatants and proteoglycan release by the dimethylmethylene blue assay. Matrix metalloproteinase (MMP)-1, MMP-13, and tissue inhibitor of metalloproteinase 1 release were measured by specific enzyme linked immunosorbent assays (ELISAs), and collagenolytic activity was measured by a bioassay using radiolabelled collagen.

RESULTS

OSM in combination with either IL1 or TNFalpha acted synergistically to induce collagenolysis from HNC, with a maximum of 79% collagen release. This degradation strongly correlated with MMP-1 and MMP-13 levels and collagenolytic activity.

CONCLUSION

Collagen release from human cartilage is marked and implicates both MMP-1 and MMP-13 in the synergistic degradation of human cartilage by OSM in combination with either IL1 or TNFalpha. HNC responds in the same way as BNC, thus validating the bovine cartilage degradation assay as a model relevant to human disease.

Endogenously produced adenosine regulates articular cartilage matrix homeostasis: enzymatic depletion of adenosine stimulates matrix degradation

OBJECTIVE

Enhanced extracellular levels of adenosine have been shown to inhibit experimentally induced cartilage degradation. The objective of this study was to investigate the role of adenosine and A(2)adenosine receptors in regulating cartilage homeostasis in the absence of inflammatory stimuli.

METHODS

Cartilage explants were exposed to adenosine deaminase (ADA) to deplete extracellular adenosine, and conditioned medium was collected for evaluation of glycosaminoglycan (GAG), prostaglandin E(2)(PGE(2)), nitric oxide (NO), and matrix metalloproteinases-3 and -13 (MMP-3, MMP-13) levels. In a second set of experiments, cartilage incubated with ADA was simultaneously exposed to the adenosine kinase inhibitor 5'-iodotubercidin (ITU) to inhibit adenosine breakdown, or to the A(2A)adenosine receptor agonist N(6)-[2-(3,5-dimethoxyphenyl)-ethyl]adenosine (DPMA). Finally, explants were incubated with the adenosine receptor antagonists ZM241385, CGS15943, theophylline or caffeine to block normal receptor activation by endogenous adenosine.

RESULTS

Exposure to ADA induced a concentration-dependent increase in GAG release and production of total MMP-3, MMP-13, PGE(2), and NO. Both ITU and DPMA inhibited the ADA-mediated increases in GAG release and PGE(2), and NO production, but only ITU inhibited MMP-13 release. Exposure to ZM 241385 increased GAG, MMP-3 and MMP-13 release. Additionally, CGS 15943 increased MMP-3 production while theophylline increased GAG, PGE(2), and NO release.

CONCLUSIONS

Endogenous adenosine levels appear to regulate cartilage matrix homeostasis even in the absence of inflammation. Regulation occurs, at least in part, through activation of cell surface receptors. This study suggests that autocrine and paracrine responses to adenosine release are important for maintenance of healthy articular cartilage.

Interleukin 17 synergises with tumour necrosis factor alpha to induce cartilage destruction in vitro

BACKGROUND

Interleukin 17 (IL17) is produced by activated T cells and has been implicated in the development of bone lesions and cartilage degradation in rheumatoid arthritis (RA).

OBJECTIVE

To determine whether IL17, alone or together with tumour necrosis factor alpha (TNFalpha), induces cartilage destruction in vitro.

METHODS

Fetal mouse metatarsals stripped of endogenous osteoclast precursors were used to study the effect of IL17 on cartilage degradation independently of osteoclastic resorption. Cartilage destruction was analysed histologically by Alcian blue staining.

RESULTS

IL17 alone, up to 100 ng/ml, had no effect on the cartilage of fetal mouse metatarsals. IL17 (>/=0.1 ng/ml), however, induced severe cartilage degradation when given together with TNFalpha (>/=1 ng/ml). The cytokine combination decreased Alcian blue staining, a marker of proteoglycans, throughout the metatarsals and induced loss of the proliferating and early hypertrophic chondrocyte zones. TNFalpha alone also decreased Alcian blue staining, but not as dramatically as the cytokine combination. In addition, it did not induce loss of chondrocyte zones. Treatment with inhibitors of matrix metalloproteinase (MMP) activity and nitric oxide synthesis showed that MMP activity played a part in cartilage degradation, whereas nitric oxide production did not.

CONCLUSIONS

IL17, together with TNFalpha, induced cartilage degradation in fetal mouse metatarsals in vitro. IL17 may, therefore, participate in the development of cartilage destruction associated with RA by enhancing the effects of TNFalpha and may provide a potential therapeutic target.

Matrix metalloproteinases in arthritic disease

The role of matrix metalloproteinases in the degradative events invoked in the cartilage and bone of arthritic joints has long been appreciated and attempts at the development of proteinase inhibitors as potential therapeutic agents have been made. However, the spectrum of these enzymes orchestrating connective tissue turnover and general biology is much larger than anticipated. Biochemical studies of the individual members of the matrix metalloproteinase family are now underway, ultimately leading to a more detailed understanding of the function of their domain structures and to defining their specific role in cellular systems and the way that they are regulated. Coupled with a more comprehensive and detailed study of proteinase expression in different cells of joint tissues during the progress of arthritic diseases, it will be possible for the future development and application of highly specific proteinase inhibitors to be directed at specific key cellular events.