Expression of membrane-type 1 matrix metalloproteinase in rheumatoid synovial cells

Pathophysiological landscape of osteoarthritis

A sharp rise in osteoarthritis (OA) incidence is expected as over 25% of world population ages in the coming decade. Although OA is considered a degenerative disease, mounting evidence suggests a strong connection with chronic metabolic conditions and low-grade inflammation. OA pathology is increasingly understood as a complex interplay of multiple pathological events including oxidative stress, synovitis and immune responses revealing its intricate nature. Cellular, biochemical and molecular aspects of these pathological events along with major outcomes of the relevant research studies in this area are discussed in the present review. With reference to their published and unpublished work, the authors strongly propose synovitis as a central OA pathology and the key OA pathological events are described in connection with it. Recent research outcomes also have succeeded to establish a linkage between metabolic syndrome and OA, which has been precisely included in the present review. Impact of aging process cannot be neglected in OA. Cell senescence is an important mechanism of aging through which it facilitates development of OA like other degenerative disorders, also discussed within a frame of OA. Conclusively, the reviewers urge low-grade inflammation linked to aging and derailed immune function as a pathological platform for OA development and progression. Thus, interventions targeted to prevent inflammaging hold a promising potential in effective OA management and efforts should be invested in this direction.

Gypenoside inhibits interleukin-1β-induced inflammatory response in human osteoarthritis chondrocytes

Gypenoside (GP), the main active ingredient of Gynostemma pentaphyllum, possesses a variety of pharmacological capacities including anti-inflammation, anti-oxidation, and anti-tumor. However, the effects of GP on IL-1β-stimulated human osteoarthritis (OA) chondrocytes are still unknown. Therefore, this study aimed to investigate the anti-inflammatory effects of GP on IL-1β-stimulated human OA chondrocytes and explore the possible mechanism. Our results showed that GP dose-dependently inhibited IL-1β-induced NO and PGE2 production in human OA chondrocytes. In addition, treatment of GP inhibited the expression of MMP3 and MMP13, which was increased by IL-1β. Finally, we found that pretreatment of GP obviously suppressed NF-κB activation in IL-1β-stimulated human OA chondrocytes. Taken together, the results demonstrated that GP has chondro-protective effects, at least in part, through inhibiting the activation of NF-κB signaling pathway in human OA chondrocytes. Thus, these findings suggest that GP may be considered as an alternative therapeutic agent for the management of OA patients.

Discoidin domain receptor 2 mediates collagen-induced activation of membrane-type 1 matrix metalloproteinase in human fibroblasts

Membrane-type 1 matrix metalloproteinase (MT1-MMP) is a membrane-bound MMP that is highly expressed in cells with invading capacity, including fibroblasts and invasive cancer cells. However, pathways of MT1-MMP up-regulation are not clearly understood. A potential physiological stimulus for MT1-MMP expression is fibrillar collagen, and it has been shown that it up-regulates both MT1-MMP gene and functions in various cell types. However, the mechanisms of collagen-mediated MT1-MMP activation and its physiological relevance are not known. In this study, we identified discoidin domain receptor 2 (DDR2) as a crucial receptor that mediates this process in human fibroblasts. Knocking down DDR2, but not the β1 integrin subunit, a common subunit for all collagen-binding integrins, inhibited the collagen-induced MT1-MMP-dependent activation of pro-MMP-2 and up-regulation of MT1-MMP at the gene and protein levels. Interestingly, DDR2 knockdown or pharmacological inhibition of DDR2 also inhibited the MT1-MMP-dependent cellular degradation of collagen film, suggesting that cell-surface collagen degradation by MT1-MMP involves DDR2-mediated collagen signaling. This DDR2-mediated mechanism is only present in non-transformed mesenchymal cells as collagen-induced MT1-MMP activation in HT1080 fibrosarcoma cells and MT1-MMP function in MDA-MB231 breast cancer cells were not affected by DDR kinase inhibition. DDR2 activation was found to be noticeably more effective when cells were stimulated by collagen without the non-helical telopeptide region compared with intact collagen fibrils. Furthermore, DDR2-dependent MT1-MMP activation by cartilage was found to be more efficient when the tissue was partially damaged. These data suggest that DDR2 is a microenvironment sensor that regulates fibroblast migration in a collagen-rich environment.

Detection of a latent soluble form of membrane type 1 matrix metalloprotease bound with tissue inhibitor of matrix metalloproteinases-2 in periprosthetic tissues and fluids from loose arthroplasty endoprostheses

Membrane type 1 matrix metalloproteinase (MT1-MMP) is implicated in pericellular proteolysis, and, together with tissue inhibitor of matrix metalloproteinases-2 (TIMP-2), in the activation of pro-matrix metalloproteinase-2 on the cell surface. It is expressed on the cell surface either activated or as a proenzyme. A soluble form of MT1-MMP (sMT1-MMP) has been previously identified in periprosthetic tissues and fluid of patients with loose arthroplasty endoprostheses. The aim of this study was to examine periprosthetic tissues and fluids from patients with loose arthroplasty endoprostheses, as well as tissues and fluids from patients with other disorders, for the presence of sMT1-MMP, and to investigate its activation state and possible role. With antibody against MT1-MMP, a protein with molecular mass of ~ 57 kDa was detected by western blotting in all samples tested, representing a soluble form of MT1-MMP, which cannot be ascribed to alternative splicing, as northern blotting showed only one transcript. With various biochemical methods, it was shown that this species occurs in a latent form bearing the N-terminal prodomain, and, additionally, it is bound to TIMP-2, which appeared to be bound via its C-terminal domain to a site different from the active site. Cell ELISA and immunohistochemical analysis revealed that, besides fibroblasts, all other cells, such as inflammatory, epithelial, endothelial, giant and cancer cells, express MT1-MMP on their plasma membrane as a proenzyme. Taking into account the proteolytic abilities of MT1-MMP, the latent sMT1-MMP-TIMP-2 complex could be considered as a new interstitial collagenase. However, the exact role, the production mechanism and the cell origin of this complex remain to be elucidated.

Membrane-type I matrix metalloproteinase-dependent regulation of rheumatoid arthritis synoviocyte function

In rheumatoid arthritis, the coordinated expansion of the synoviocyte mass is coupled with a pathologic angiogenic response that leads to the destructive remodeling of articular as well as surrounding connective tissues. Although rheumatoid synoviocytes express a multiplicity of proteolytic enzymes, the primary effectors of cartilage, ligament, and tendon damage remain undefined. Herein, we demonstrate that human rheumatoid synoviocytes mobilize the membrane-anchored matrix metalloproteinase (MMP), membrane-type I MMP (MT1-MMP), to dissolve and invade type I and type II collagen-rich tissues. Though rheumatoid synoviocytes also express a series of secreted collagenases, these proteinases are ineffective in mediating collagenolytic activity in the presence of physiologic concentrations of plasma- or synovial fluid-derived antiproteinases. Furthermore, MT1-MMP not only directs the tissue-destructive properties of rheumatoid synoviocytes but also controls synoviocyte-initiated angiogenic responses in vivo. Together, these findings identify MT1-MMP as a master regulator of the pathologic extracellular matrix remodeling that characterizes rheumatoid arthritis as well as the coupled angiogenic response that maintains the aggressive phenotype of the advancing pannus.

Different expression levels of TNF receptors on the rheumatoid synovial macrophages derived from surgery and a synovectomy as detected by a new flow cytometric analysis

TNFalpha plays a crucial role in the pathogenesis of rheumatoid arthritis. It is very important to examine the expression of the TNF receptors, the ligand of TNFalpha. In this study, we developed a triple-color flow cytometric analysis using CD45 and CD14 monoclonal antibodies to simply detect the expression of the TNF receptors on the heterogeneous rheumatoid synovial cells. Using this system, we detected a higher population of macrophages and a greater TNF receptor expression on the synovial macrophages derived from a synovectomy in comparison to the findings obtained from knee joint replacement surgery.

Invasive potential of human rheumatoid tenosynovial cells is in part MT1-MMP dependent

PURPOSE

In rheumatoid arthritis, tenosynovial invasion of tendon is associated with an increased rate of tendon rupture and a worse clinical prognosis compared to noninvasive disease. Tendon is composed predominantly of type I collagen, which can be efficiently degraded by collagenolytic matrix metalloproteinases (MMPs), one of which, MT1-MMP, is membrane bound and inhibited by tissue inhibitor of metalloproteinase-2, but not by TIMP-1. The role of MT1-MMP in tendon disease is unknown. In this report, we investigate the potential role of MT1-MMP in invasion of tenosynovium into tendon.

METHODS

Matched synovial specimens were obtained from different regions of the wrist in 36 rheumatoid patients having extensor tenosynovectomy in most instances. The tenosynovium that was removed was surrounding tendons (termed encapsulating) invading tendons (termed invasive), and wrist joint synovium. Samples of tenosynovium were tested for MT1-MMP using Western blotting, and the MT1-MMP activity was quantified using commercial assays. Next, a 3-dimensional collagen assay was created, using freshly isolated tenosynovium. Transwell collagen invasion assays were then performed, using isolated tenosynovial cells to determine MT1-MMP's effect on tendon invasion.

RESULTS

The MT1-MMP was present in 9 of 10 joint samples, 4 of 6 encapsulating tenosynovial samples, and 5 of 5 invasive tenosynovial samples. Activity assays demonstrated that mean levels of active MT1-MMP produced by joint samples was 6.1 +/- 4.1 ng/mL; by encapsulating tenosynovium was 3.9 +/- 4.2 ng/mL, and by invasive tenosynovium was 6.2 +/- 1.1 ng/mL. The 3-dimensional gel assays demonstrated that cell invasion was reduced by the addition of TIMP-2 and GM-6001(a broad spectrum matrix metalloproteinase inhibitor) but not by TIMP-1. The addition of TIMP-2 to invasion assays reduced the mean number of cells that invaded the collagen membrane from 11 +/- 5 cells/field to 7 +/- 3 cells/field in treated samples (p = .04).

CONCLUSIONS

Our results demonstrate that MT1-MMP is present in rheumatoid tenosynovium and that MT1-MMP facilitates tenosynovial cell invasion into a type I collagen matrix, suggesting that MT1-MMP plays a crucial role in tendon invasion.

TYPE OF STUDY/LEVEL OF EVIDENCE

Prognostic IV.

The second dimer interface of MT1-MMP, the transmembrane domain, is essential for ProMMP-2 activation on the cell surface

Activation of proMMP-2 and cell surface collagenolysis are important activities of membrane-type 1 matrix metalloproteinase (MT1-MMP) to promote cell migration in tissue, and these activities are regulated by homodimerization of MT1-MMP on the cell surface. In this study, we have identified the transmembrane domain as a second dimer interface of MT1-MMP in addition to the previously identified hemopexin domain. Our analyses indicate that these two modes of dimerization have different roles; transmembrane-dependent dimerization is critical for proMMP-2 activation, whereas hemopexin-dependent dimerization is important for degradation of collagen on the cell surface. Our finding provides new insight into the potential molecular arrangement of MT1-MMP contributing to its function on the cell surface.

Cells of the synovium in rheumatoid arthritis. Synovial fibroblasts

For some time synovial fibroblasts have been regarded simply as innocent synovial cells, mainly responsible for synovial homeostasis. During the past decade, however, a body of evidence has accumulated illustrating that rheumatoid arthritis synovial fibroblasts (RASFs) are active drivers of joint destruction in rheumatoid arthritis. Details regarding the intracellular signalling cascades that result in long-term activation and synthesis of proinflammatory molecules and matrix-degrading enzymes by RASFs have been analyzed. Molecular, cellular and animal studies have identified various interactions with other synovial and inflammatory cells. This expanded knowledge of the distinct role played by RASFs in the pathophysiology of rheumatoid arthritis has moved these fascinating cells to the fore, and work to identify targeted therapies to inhibit their joint destructive potential is underway.

Retroviral gene transfer of an antisense construct against membrane type 1 matrix metalloproteinase reduces the invasiveness of rheumatoid arthritis synovial fibroblasts

OBJECTIVE

Membrane type 1 matrix metalloproteinase (MT1-MMP) is expressed prominently in rheumatoid arthritis synovial fibroblasts (RASFs), but the specific contribution of MT1-MMP to fibroblast-mediated destruction of articular cartilage is incompletely understood. This study used gene transfer of an antisense expression construct to assess the effects of MT1-MMP inhibition on the invasiveness of RASFs.

METHODS

Retroviral gene transfer of a pLXIN vector-based antisense RNA expression construct (MT1-MMPalphaS) to MT1-MMP was used to stably transduce RASFs. Levels of MT1-MMP RNA and protein were determined by quantitative polymerase chain reaction, Western blotting, and immunocytochemistry in MT1-MMPalphaS-transduced RASFs as well as in control cells, with monitoring for 60 days. The effects of MT1-MMPalphaS on the invasiveness of RASFs were analyzed in the SCID mouse co-implantation model of RA.

RESULTS

MT1-MMPalphaS-transduced RASFs produced high levels of antisense RNA that exceeded endogenous levels of MT1-MMP messenger RNA by 15-fold and resulted in a down-regulation of MT1-MMP at the protein level. Inhibition of MT1-MMP production was maintained for 60 days and significantly reduced the invasiveness of RASFs in the SCID mouse model. Whereas prominent invasion into cartilage by non-transduced and mock-transduced RASFs was observed (mean invasion scores 3.0 and 3.1, respectively), MT1-MMPalphaS-transduced cells showed only moderate invasiveness (mean invasion score 1.8; P < 0.05).

CONCLUSION

The data demonstrate that an antisense RNA expression construct against MT1-MMP can be generated and expressed in RASFs for at least 60 days. Inhibition of MT1-MMP significantly reduces the cartilage degradation by RASFs.

Transmembrane proteases in cell growth and invasion: new contributors to angiogenesis?

Transmembrane proteases (TPs) are proteins anchored in the plasma membrane with their catalytic site exposed to the external surface of the membrane. TPs are widely expressed, and their dysregulated expression is associated with cancer, infection, inflammation, autoimmune and cardiovascular diseases, all diseases where angiogenesis is part of the pathology. TPs participate in extracellular proteolysis (degradation of extracellular matrix components, regulation of chemokine activity, release of membrane-anchored cytokines, cytokine receptors and adhesion molecules) and influence cell functions (growth, secretion of angiogenic molecules, motility). Recent attention has been focused on the ADAM-17 (a disintegrin and metalloprotease)/TACE/CD156q, the MT1-MMP (membrane-type-1 matrix metallo proteinase)/MMP-14, and the ectopeptidases aminopeptidase N (APN/CD13), dipeptidyl peptidase IV (DPPIV/CD26) and angiotensin-converting enzyme (ACE/CD143), that appear to have a critical role in angiogenesis. This article summarizes current knowledge on these TPs, and reviews recent investigations that document their participation during angiogenic-related events. Through their multiple roles, TPs may thereby provide critical links in angiogenesis.