Structural analysis of the catalytic domain of human fibroblast collagenase

A critical role for proinflammatory behavior of smooth muscle cells in hemodynamic initiation of intracranial aneurysm

Background

Intracranial aneurysm initiation is poorly understood, although hemodynamic insult is believed to play an important role in triggering the pathology. It has recently been found in a rabbit model that while macrophages are absent during hemodynamic aneurysm initiation, matrix metalloproteinases (MMPs) are elevated and co-localize with smooth muscle cells (SMCs). This study investigates whether SMCs play a mechanistic role in aneurysm initiation triggered by hemodynamics.

Methods

Aneurysmal damage was induced at the basilar terminus via bilateral common carotid artery ligation in rabbits (n = 45, plus 7 sham controls). 16 ligated rabbits were treated with doxycycline to inhibit MMPs, 7 received clodronate liposomes to deplete circulating monocytes, and the rest received no drug. Effects of the treatments on aneurysm development were assessed histologically 5 days and 6 months after ligation. MMP production and expression of inflammatory markers by SMCs was monitored by immunohistochemistry and in situ hybridization.

Results

Treatment with doxycycline attenuated aneurysmal development examined at 5 days and 6 months, suggesting that MMPs contribute to aneurysm initiation. However, systemic depletion of macrophages did not decrease MMPs or suppress aneurysmal development. Immunofluorescence showed that during aneurysm initiation MMP-2 and MMP-9 were distributed in SMCs, and in situ hybridization indicated that they were transcribed by SMCs. In regions of early aneurysmal lesion, SMCs exhibited decreased expression of smooth muscle actin and increased NF-κB and MCP-1 expressions.

Conclusions

During aneurysm initiation triggered by hemodynamics, SMCs rather than macrophages are responsible for MMP production that is critical for aneurysmal lesion development. These SMCs exhibit proinflammatory behavior.

Orally active MMP-1 sparing α-tetrahydropyranyl and α-piperidinyl sulfone matrix metalloproteinase (MMP) inhibitors with efficacy in cancer, arthritis, and cardiovascular disease

α-Sulfone-α-piperidine and α-tetrahydropyranyl hydroxamates were explored that are potent inhibitors of MMP's-2, -9, and -13 that spare MMP-1, with oral efficacy in inhibiting tumor growth in mice and left-ventricular hypertrophy in rats and in the bovine cartilage degradation ex vivo explant system. α-Piperidine 19v (SC-78080/SD-2590) was selected for development toward the initial indication of cancer, while α-piperidine and α-tetrahydropyranyl hydroxamates 19w (SC-77964) and 9i (SC-77774), respectively, were identified as backup compounds.

Doxycycline causes regression of endometriotic implants: a rat model

BACKGROUND

Doxycycline (Dox) has a number of non-antibiotic properties. One of them is the inhibition of matrix metalloproteinase (MMP) activity. The aim of this study was to assess the effects of Dox in a rat endometriosis model.

METHODS

Endometriosis was surgically induced in 40 rats by transplanting of endometrial tissue. After 3 weeks, repeat laparotomies were performed to check the implants and the animals were randomized into four groups: Group I, low-dose Dox (5 mg/kg/day); Group II, high-dose Dox (40 mg/kg/day); Group III, leuprolide acetate 1 mg/kg single dose, s.c.; and Group VI (controls), no medication. The treatment, initiated on the day of surgery and continuing for 3 weeks, was administered to the study groups. Three weeks later, the rats were euthanized and the implants were evaluated morphologically and histologically for immunoreactivity of MMP-2 and -9, and interleukin-6 (IL-6) concentration in the peritoneal fluid was assayed.

RESULTS

Treatment with leuprolide acetate, or high-dose or low-dose Dox caused significant decreases in the implant areas compared with the controls (P = 0.03, P = 0.006, and P = 0.001, respectively). IL-6 levels in peritoneal fluid decreased in Group I (P = 0.02) and Group III (P < 0.05). MMP H scores were significantly lower in the group that received low-dose Dox in both epithelial and stromal MMP-2 and -9 immunostaining when compared with the control group [P = 0.048, P = 0.002, P = 0.007 and P = 0.002, respectively, MMP-2 (epithelia), MMP-2 (stroma), MMP-9 (epithelia) and MMP-9 (stroma)].

CONCLUSIONS

Low-dose Dox caused regression of endometriosis in this experimental rat model.

Doxycycline may reduce the incidence of aneurysms in haemodialysis vascular accesses

BACKGROUND

Doxycycline can prevent aortic aneurysms through the inhibition of enzymes that degrade vessel walls. We investigated whether haemodialysis patients who had received one or more courses of doxycycline were at less risk for aneurysms in their vascular accesses than those who had received other antibiotics.

METHODS

Three hundred and eight patients undergoing chronic maintenance hemodialysis were evaluated for aneurysm formation after exposure to doxycycline or another antibiotic. Conditional forward logistical analysis using Cox proportional hazards test (SPSS) was performed to determine the potential significance of differences of aneurysm formation between the two groups.

RESULTS

Patients who had received doxycycline appeared to be at lower risk than the control group, but the effect was most obvious in those patients with synthetic grafts.

CONCLUSIONS

Doxycycline may have the ability to reduce aneurysm formation in haemodialysis vascular accesses and a large prospective study is warranted.

Hyperoxia decreases matrix metalloproteinase-9 and increases tissue inhibitor of matrix metalloproteinase-1 protein in the newborn rat lung: association with arrested alveolarization

Matrix metalloproteinases (MMP) are likely effectors of normal lung development, especially branching morphogenesis, angiogenesis, and extracellular matrix degradation. Because hyperoxia exposure (>95% O(2)) from d 4 to 14 in newborn rat pups leads to arrest of alveolarization and mimics newborn chronic lung disease, we tested whether hyperoxia altered MMP-2 and -9 mRNA, protein, and enzymatic activity, and the mRNA and protein expression of the endogenous tissue inhibitor of MMP, TIMP-1. No changes due to hyperoxia exposure were observed in MMP-2 mRNA or pro-enzyme (72 kD) protein levels between d 6 and 14, although the overall protein mass and zymographic activity of the active (68 kD) enzyme were diminished (p < 0.05, ANOVA). However, hyperoxia significantly decreased levels of MMP-9 mRNA and pro-MMP-9 protein and diminished overall MMP-9 pro-enzyme activity. TIMP-1 mRNA was not elevated by hyperoxia until d 14, but protein levels were significantly (p < 0.001) elevated by hyperoxia from d 9 to 14. To estimate the potential of MMP inhibition to arrest alveolarization, administration of doxycycline (20 mg/kg, twice daily by gavage), a pan-MMP proteolysis inhibitor, arrested lung alveolarization. We conclude that hyperoxia decreases MMP-9 mRNA, protein, and activity and elevates TIMP-1 protein, and these changes have the potential to contribute to the arrest of normal lung development.

High-resolution solution structure of the catalytic fragment of human collagenase-3 (MMP-13) complexed with a hydroxamic acid inhibitor

The high-resolution solution structure of the catalytic fragment of human collagenase-3 (MMP-13) complexed with a sulfonamide derivative of a hydroxamic acid compound (WAY-151693) has been determined by multidimensional heteronuclear NMR. A total of 30 structures were calculated for residues 7-164 by means of hybrid distance geometry-simulated annealing using a total of 3280 experimental NMR restraints. The atomic rms distribution about the mean coordinate positions for the 30 structures is 0.43(+/-0.05) A for the backbone atoms, 0.80(+/-0.09) A for all atoms, and 0.47(+/-0.04) A for all atoms excluding disordered side-chains. The overall structure of MMP-13 is composed of a beta-sheet consisting of five beta-strands in a mixed parallel and anti-parallel arrangement and three alpha-helices where its overall fold is consistent with previously solved MMP structures. A comparison of the NMR structure of MMP-13 with the published 1.6 A resolution X-ray structure indicates that the major differences between the structures is associated with loop dynamics and crystal-packing interactions. The side-chains of some active-site residues for the NMR and X-ray structures of MMP-13 adopt distinct conformations. This is attributed to the presence of unique inhibitors in the two structures that encounter distinct interactions with MMP-13. The major structural difference observed between the MMP-13 and MMP-1 NMR structures is the relative size and shape of the S1' pocket where this pocket is significantly longer for MMP-13, nearly reaching the surface of the protein. Additionally, MMP-1 and MMP-13 exhibit different dynamic properties for the active-site loop and the structural Zn-binding region. The inhibitor WAY-151693 is well defined in the MMP-13 active-site based on a total of 52 distance restraints. The binding motif of WAY-151693 in the MMP-13 complex is consistent with our previously reported MMP-1:CGS-27023A NMR structure and is similar to the MMP-13: RS-130830 X-ray structure.

Production and inhibition of the gelatinolytic matrix metalloproteinases in a human model of vein graft stenosis

OBJECTIVES

human vein graft stenoses are caused by intimal hyperplasia, a process which is characterised by extensive degradation and accumulation of extracellular matrix. This study investigated the role of the matrix metalloproteinases (MMPs) - the principal physiological mediators of extracellular matrix degradation - in the development of intimal hyperplasia in cultured human long saphenous vein.

DESIGN

experimental study.

MATERIALS AND METHODS

paired venous segments with the endothelium intact or denuded were cultured in standard conditions for 14 days. At the termination of culture, MMPs were extracted from one half of the tissue, whilst the remainder of the vein was prepared for histological examination.

RESULTS

stereologic analysis revealed that the endothelium intact veins developed a significantly thicker neointima when compared to the denuded venous segments (20 micron v. 0 micron, p=0.006). Quantification of MMPs by substrate gel enzymography demonstrated that the development of a neointima was associated with increased production of the gelatinolytic MMP-9 (p=0. 03) in intact veins. Immunocytochemistry showed that the MMP-9 localised to the internal elastic lumina, which suggested a role in facilitating smooth-muscle-cell migration into the intima. The role of MMPs-2 and -9 in intimal hyperplasia was further investigated by culturing intact venous segments with a therapeutic concentration of doxycycline--a potent MMP inhibitor. These experiments demonstrated that a therapeutic dose of doxycycline significantly reduced neointimal thickness (control 21 micron, doxycycline 10 mg/l-5.5 micron), in conjunction with a significant reduction in the production of MMP-9.

CONCLUSIONS

these data suggest that elevated levels of MMPs may play a significant role in the development of human intimal hyperplasia and that inhibition of these enzymes may offer a potential therapeutic strategy for the prevention of hyperplastic lesions.

N-glycan structures of matrix metalloproteinase-1 derived from human fibroblasts and from HT-1080 fibrosarcoma cells

Matrix metalloproteinase-1 (MMP-1) is a collagenolytic metalloproteinase capable of cleaving native triple-helical forms of several collagen subtypes, as well as a number of non-collagenous substrates. The role of MMP-1 in various diseases affecting the connective tissue is well characterized. MMP-1 is secreted as both glycosylated and unglycosylated species, and the two forms have been shown to be identical with respect to substrate specificity, specific activity and inhibitory profile. No function for the glycan moiety of the enzyme has been ascribed to date. In the present study, we report on the detailed characterization of MMP-1-derived oligosaccharides. Using strategies based on sequential exoglycosidase digestion combined with matrix-assisted laser desorption ionization-time of flight MS and electrospray tandem MS, we have characterized the N-glycan structures of MMP-1, derived from human dermal fibroblasts and from the HT-1080 fibrosarcoma cell line. MMP-1 derived from fibroblasts was found to carry mainly alpha 2,3-sialylated complex-type diantennary glycans. On the other hand, HT-1080 cells produce MMP-1 that has a heterogeneous glycosylation pattern, comprising diantennary glycans carrying Lewis X, LacdiNAc, sialylated LacdiNAc and GalNAc beta 1,4 (Fuc alpha 1,3)GlcNAc (LacdiNAc analogue of Lewis X) as terminal elements. We also show that, of the two potential glycosylation sites in the MMP-1 sequence, only Asn120 is used.

Doxycycline inhibits elastin degradation and reduces metalloproteinase activity in a model of aneurysmal disease

PURPOSE

Abdominal aortic aneurysms are characterized by degradation of the extracellular matrix, with a reduction in the elastin concentration of the arterial media. These changes are mediated by increased levels of endogenous metalloproteinases (MMPs) within the aorta, which provide a potential therapeutic target for pharmacologic agents aimed at reducing the growth rate of small aneurysms. In this study, the ability of doxycycline--an MMP inhibitor--to reduce matrix degradation was assessed in a previously described model of aneurysmal disease that used a brief pulse of elastase to induce MMP production and elastin degradation in arterial organ cultures.

METHODS

Porcine aortic segments (n = 8) were preincubated in exogenous pancreatic elastase for 24 hours before culture in standard conditions for 13 days with both 1 and 10 mg/L doxycycline. Control segments were cultured both without doxycycline and without elastase. At the termination of culture, MMPs were extracted from the tissue and quantified by a combination of substrate gel enzymography and immunoblotting. The volume fractions of elastin and collagen were determined by stereologic analysis of sections stained with Miller's elastin and van Gieson's stain.

RESULTS

Stereologic analysis demonstrated a significant preservation of elastin in aorta treated with doxycycline 10 mg/L (p < 0.001) and demonstrated that this preservation was accompanied by a significant reduction in MMP-9 activity (p < 0.02). Immunoblotting for tissue inhibitors of metalloproteinases (TIMP-1 and TIMP-2) showed no decreased production in the doxycycline-treated groups.

CONCLUSIONS

Therapeutic ranges of doxycycline significantly inhibited elastin degradation and MMP-9 production within aortic organ cultures. These data suggest that doxycycline may have a potential application in reducing the growth rates of small abdominal aortic aneurysms.