Mast cell proteinases activate precursor forms of collagenase and stromelysin, but not of gelatinases A and B

Abstract

Mast cell activation in vivo is often associated with areas of oedema and connective-tissue degradation. Tryptase and chymase are the major serine proteinases released by mast cells, but they appear to have little activity on most components of the extracellular matrix. The matrix metalloproteinases (MMP) are purported to degrade almost all connective tissue elements and are secreted by cells in the form of inactive precursors. Since the mechanisms of MMP activation in vivo are poorly understood we have examined the potential of mast cell proteinases to activate the precursor forms of human collagenase (MMP-l), stromelysin (MMP-3), gelatinase A (MMP-2) and gelatinase B (MMP-9).Mast cell proteinases prepared from purified dog mastocytoma cells were shown to process and activate purified precursor forms of both MMP-1 and MMP-3. Using antipain and chymostatin, inhibitors for tryptase and chymase, respectively, it was demonstrated that both pMMP-1 and pMMP-3 were effectively processed and activated by the chymase component. By contrast, tryptase activated only pMMP-3. The mast cell proteinases were unable to process or activate purified precursor forms of MMP-2 and MMP-9. However, MMP-3 previously activated by mast cell proteinases was shown to activate pMMP-9, but not pMMP-2. Since we have no evidence that mast cells express these four metalloenzymes, the release of mast cell serine proteinases following activatioddegranulation could contribute to local metalloproteinase activation and subsequent matrix degradation.Although numerous enzymes may contribute to the degradation of connective tissues, the family of metalloproteinases is of particular interest since they are purported to degrade almost all components of the extracellular matrix [l, 21. These enzymes are grouped into three main subclasses : interstitial [matrix metalloproteinase (MMP)-11 and polymorphonuclear (MMP-8) collagenases which degrade type I, I1 and I11 collagens; gelatinases A and B [MMP-2 (72 kDa) and MMP-9 (92 m a ) ] which degrade basement-membrane type IV collagen and gelatin; and stromelysins (MMP-3, MMP-10) with activity on a broad spectrum of substrates including proteoglycans, laminin, fibronectin and some collagen species [3]. While expressing different substrate specificities these metalloenzymes share some conserved sequence similarity and activation mechanisms [2]. All the metalloproteinases are secreted as precursor forms requiring extracellular activation prior to substrate attack. Activation of the pro- ~-enzymes has been demonstrated in vitro by proteolytic cleavage of their propeptide domains and also by organomercurial compounds such as aminophenyl mercuric acetate (H,NPhHgAc) [2, 4-61, but the activation mechanisms that function in vivo remain unclear.Since mast cells are commonly associated with sites of connective-tissue lysis, for example at sites of tumour invasion in melanoma and breast carcinoma [7, 81 and at cartilage erosion sites in rheumatoid arthritis [9], a potential role for this cell in matrix degradation has be...

Emerging roles of serine proteinases in tissue turnover in arthritis

“…Tryptase can process prothrombin (74), generate C3a from complement C3 (75), and degrade ECM components including fibrinogen (76,77), denatured type I collagen (78), and fibronectin (79). Tryptase and chymase can further promote ECM degradation by activating proMMPs (80)(81)(82)(83)(84) and pro-uPA (85). Mast cell tryptase is important in activating PAR-2 on synovial fibroblasts and inducing proinflammatory cytokine release (86,87).…”

“…Thus, cartilage resorption involves both metalloproteinases and serine proteinases, which are likely to function through a series of interacting cascades (Figure 2). A large number of serine proteinases have been shown to activate proMMPs, especially proMMP-3 (trypsin, chymotrypsin, tryptase, chymase, plasmin, plasma kallikrein, NE, CTG, trypsinogen 2, thrombin, and matriptase) (38,81,84,(189)(190)(191)(192). However, the precise activation mechanisms for many of the proMMPs that occur in vivo in both cartilage and other matrices are unknown (175).…”

Purification, Characterization and Biological Evaluation of Recombinant Leech‐Derived Tryptase Inhibitor (rLDTI) Expressed at High Level in the Yeast Saccharomyces Cerevisiae

“…These include allergic and inflammatory disorders such as asthma, psoriasis, interstitial lung diseases, rheumatoid arthritis, gingivitis and peridontitis (for reviews, see Miller and Schwartz, 1989 ;Caughey, 1991 ;Eklund and Stevens, 1993 ;Sommerhoff, 1995). Mast cell tryptase has also been implicated in tumorgenesis and angiogenesis due to its potential to activate pro-urokinase and the matrix metalloproteinase pro-stromelysin (Stack and Johnson, 1994;Lees et al, 1994), enzymes involved in matrix degradation. Recently, a tryptase-like enzyme activity was detected in several breast cancer cell lines (McIlroy et al, 1994).…”

Activation of Matrix-Degrading Metalloproteinases by Mast Cell Proteases in Atherosclerotic Plaques

“…Proteolytic activation of pro-MMPs has been achieved in vitro by using trypsin, chymotrypsin, plasma kallikrein, plasmin, thermolysin, 15 chymase, and tryptase. 16 Furthermore, MMPs can activate each other; eg, activated MMP-3 can activate MMP-1. 17 Mast cells play pivotal roles in many biological responses, including hypersensitivity reactions, inflammation, tissue remodeling, and angiogenesis, and they are involved in the pathogenesis of chronic degenerative diseases such as asthma and rheumatoid arthritis.…”