Metalloprotease inhibitors halt collagen breakdown in IL-1 induced bovine nasal cartilage cultures

Extracellular Distribution of Collagen II and Perifibrillar Adapter Proteins in Healthy and Osteoarthritic Human Knee Joint Cartilage

Perifibrillar adapter proteins, interconnecting collagen fibrils, and linking the collagen network with the aggrecan matrix seem to play a crucial role in the pathogenesis of osteoarthritis (OA). Therefore, we examined immunohistochemically the extracellular distribution of collagen II and the main perifibrillar adapter proteins-collagen IX, decorin, cartilage oligomeric matrix protein (COMP), and matrilin-3-in human samples of healthy (n=4) and OA (n=42) knee joint cartilage. Histopathology assessment was performed using an OA score. Staining patterns were evaluated in relation to the disease stage. The perifibrillar adapter proteins were uniformly distributed in the upper zones of healthy cartilage. In moderate OA (n=8; score 14.3 ± 4.7), all proteins analyzed were locally absent in the fibrillated area or the superficial and upper mid zone. In advanced OA (n=20; score 18.9 ± 5.3), they were uniformly distributed in these zones and accumulated pericellularly. Perifibrillar adapter proteins are important for the stabilization of the collagen network in the upper zones of healthy cartilage. Their degradation might be a critical event in early OA. In advanced OA, there are indications for an increased synthesis in an attempt to regenerate the lost tissue and to protect the remaining cartilage from further destruction.

Biscarbamate cross-linked low molecular weight PEI for delivering IL-1 receptor antagonist gene to synoviocytes for arthritis therapy

Cytoxicity is an essential concern for polyethyleneimine 25 kDa (PEI 25 kDa), a widely reported, highly effective transfection agent used in gene delivery. In our recent experiments, Small molecular weight cross-linked poly(ethylene imine) by biscarbamate linkage (PEI-Bu) (Mn: 3278, Mw: 4289) can reduce target cell apoptosis induced by polycationic transfection, and has almost the same DNA condensation capability as PEI 25 kDa. PEI-Bu showed significantly higher activity and lower cytotoxicity than PEI 25 kDa in transfecting the anti-inflammatory cytokine interleukin-1 receptor antagonist (IL-1Ra) gene to rat synoviocytes, an optimal target for arthritis treatment. The expression of IL-1Ra in synoviocytes then suppresses the expression of metalloproteases 13 (MMP13) gene, which is responsible for cartilage destruction regulated by IL-1β in arthritis. In conclusion, PEI-Bu is a promising tool for delivering IL-1Ra gene to synoviocytes for arthritis therapy.

In vivo qualitative assessments of articular cartilage in the rabbit knee with high-resolution MRI at 3 T

Proteoglycan (PG) loss and disruption of the collagen framework in cartilage are early events associated with osteoarthritis (OA). The feasibility of in vivo high-resolution MRI assessments probing both macromolecules was explored in articular cartilage of the rabbit knee. One-millimeter thick coronal images were obtained at 3 T with a 97 x 97 microm(2) pixel size. A 22% decrease in the magnetization transfer (MT) exchange rate along with an approximately 2-fold greater Gd(DTPA)(2-)-induced decrease in T(1) relaxation time were measured in response to papain injection 1 day prior to the MRI session, indicative of an alteration of collagen integrity and PG depletion, respectively. A two-point method was tested as an alternative to the more time-consuming multipoint method typically used to measure T(1) changes. Kinetics of Gd(DTPA)(2-) uptake were observed with a 10-min time resolution. The diffusive transport of Gd(DTPA)(2-) was characterized by a T(1) decrease approximately 2-fold faster in papain-treated knees. These data suggest that kinetics of tracer diffusion may be used as an informative marker of PG loss, in addition to the amplitude of T(1) variations. When applied to a relevant OA model, the combination of MT and Gd(DTPA)(2-)-MRI may help in identifying new active compounds during efficacy studies on cartilage protection.

Use of an antineoepitope antibody for identification of type-II collagen degradation in equine articular cartilage

OBJECTIVE

To develop an antibody that specifically recognizes collagenase-cleaved type-II collagen in equine articular cartilage.

SAMPLE POPULATION

Cartilage specimens from horses euthanatized for problems unrelated to the musculoskeletal system.

PROCEDURE

A peptide was synthesized representing the carboxy- (C-) terminus (neoepitope) of the equine type-II collagen fragment created by mammalian collagenases. This peptide was used to produce a polyclonal antibody, characterized by western analysis for reactivity to native and collagenase-cleaved equine collagens. The antibody was evaluated as an antineoepitope antibody by ELISA, using peptides +/- an amino acid at the C-terminus of the immunizing peptide. Collagen cleavage was assayed from equine articular cartilage cultured with interleukin-1 (IL-1), +/- a synthetic MMP inhibitor, BAY 12-9566. Cartilage specimens from osteoarthritic and nonarthritic joints were compared for antibody staining.

RESULTS

An antibody, 234CEQ, recognized only collagenase-generated 3/4-length fragments of equine type-II collagen. This was a true antineoepitope antibody, as altering the C-terminus of the immunizing peptide significantly decreased competition for binding in an inhibition ELISA. The IL-1-induced release of type-II collagen fragments from articular cartilage was prevented with the MMP inhibitor. Cartilage from an osteoarthritic joint of a horse had increased staining with the 234CEQ antibody, compared with normal articular cartilage.

CONCLUSIONS AND CLINICAL RELEVANCE

We generated an antineoepitope antibody recognizing collagenase-cleaved type-II collagen of horses. This antibody detects increases in type-II collagen cleavage in diseased equine articular cartilage. The 234CEQ antibody has the potential to aid in the early diagnosis of arthritis and to monitor treatment responses.

Cyclic tensile strain suppresses catabolic effects of interleukin-1beta in fibrochondrocytes from the temporomandibular joint

OBJECTIVE

To discern the effects of continuous passive motion on inflamed temporomandibular joints (TMJ).

METHODS

The effects of continuous passive motion on TMJ were simulated by exposing primary cultures of rabbit TMJ fibrochondrocyte monolayers to cyclic tensile strain (CTS) in the presence of recombinant human interleukin-1beta (rHuIL-1beta) in vitro. The messenger RNA (mRNA) induction of rHuIL-1beta response elements was examined by semiquantitative reverse transcriptase-polymerase chain reaction. The synthesis of nitric oxide was examined by Griess reaction, and the synthesis of prostaglandin E2 (PGE2) was examined by radioimmunoassay. The synthesis of proteins was examined by Western blot analysis of the cell extracts, and synthesis of proteoglycans via incorporation of 35S-sodium sulfate in the culture medium.

RESULTS

Exposure of TMJ fibrochondrocytes to rHuIL-1beta resulted in the induction of inducible nitric oxide synthase (iNOS) and cyclooxygenase 2 (COX-2), which were paralleled by NO and PGE2 production. Additionally, IL-1beta induced significant levels of collagenase (matrix metalloproteinase 1 [MMP-1]) within 4 hours, and this was sustained over a period of 48 hours. Concomitant application of CTS abrogated the catabolic effects of IL-1beta on TMJ chondrocytes by inhibiting iNOS, COX-2, and MMP-1 mRNA production and NO, PGE2, and MMP-1 synthesis. CTS also counteracted cartilage degradation by augmenting expression of mRNA for tissue inhibitor of metalloproteinases 2 that is inhibited by rHuIL-1beta. In parallel, CTS also counteracted rHuIL-1beta-induced suppression of proteoglycan synthesis. Nevertheless, the presence of an inflammatory signal was a prerequisite for the observed CTS actions, because fibrochondrocytes, when exposed to CTS alone, did not exhibit any of the effects described above.

CONCLUSION

CTS acts as an effective antagonist of rHuIL-1beta by potentially diminishing its catabolic actions on TMJ fibrochondrocytes. Furthermore, CTS actions appear to involve disruption/regulation of signal transduction cascade of rHuIL-1beta upstream of mRNA transcription.

Cyclic tensile strain acts as an antagonist of IL-1 beta actions in chondrocytes

Inflammatory cytokines play a major role in cartilage destruction in diseases such as osteoarthritis and rheumatoid arthritis. Because physical therapies such as continuous passive motion yield beneficial effects on inflamed joints, we examined the intracellular mechanisms of mechanical strain-mediated actions in chondrocytes. By simulating the effects of continuous passive motion with cyclic tensile strain (CTS) on chondrocytes in vitro, we show that CTS is a potent antagonist of IL-1 beta actions and acts as both an anti-inflammatory and a reparative signal. Low magnitude CTS suppresses IL-1 beta-induced mRNA expression of multiple proteins involved in catabolic responses, such as inducible NO synthase, cyclo-oxygenase II, and collagenase. CTS also counteracts cartilage degradation by augmenting mRNA expression for tissue inhibitor of metalloproteases and collagen type II that are inhibited by IL-1 beta. Additionally, CTS augments the reparative process via hyperinduction of aggrecan mRNA expression and abrogation of IL-1 beta-induced suppression of proteoglycan synthesis. Nonetheless, the presence of an inflammatory signal is a prerequisite for the observed CTS actions, as exposure of chondrocytes to CTS alone has little effect on these parameters. Functional analysis suggests that CTS-mediated anti-inflammatory actions are not mediated by IL-1R down-regulation. Moreover, as an effective antagonist of IL-1 beta, the actions of CTS may involve disruption/regulation of signal transduction cascade of IL-1 beta upstream of mRNA transcription. These observations are the first to show that CTS directly acts as an anti-inflammatory signal on chondrocytes and provide a molecular basis for its actions.