Effects of cigarette smoke condensate and nicotine on human gingival fibroblast-mediated collagen degradation

BACKGROUND

Members of the matrix metalloproteinase (MMP) family have been shown to be involved in periodontal disease. Risk factors for periodontal disease include tobacco smoking. Cigarette smoke condensate (CSC) is comprised of thousands of chemicals. Nicotine is one of the active components in tobacco. This study compares the effects of CSC and nicotine at the level in CSC on the collagen-degrading ability of human gingival fibroblasts (HGFs) and the expression of selected MMPs and tissue inhibitors of metalloproteinases (TIMPs).

METHODS

HGFs were seeded in six-well collagen-coated plates, exposed to 100 μg/mL (2.4 μg/mL nicotine) of CSC or 2.4 μg/mL nicotine for 3 days, and then collagen degradation was analyzed. After 3 days exposure to CSC or nicotine, the conditioned media from HGFs was collected and the membrane proteins were extracted for gelatin zymography and Western blot analyses. The mRNA levels of MMP-2, MMP-14, and TIMP-2 were measured by reverse transcription-polymerase chain reaction.

RESULTS

The CSC increased collagen degradation, and increased the levels of TIMP-2, MMP-14, and the active MMP-2 in the membrane extracts, and their mRNA levels. CSC also increased the level of active MMP-2 in the conditioned media. Nicotine at the level in CSC (2.4 μg/mL) had little influence on collagen degradation, as well as on the protein and mRNA levels of MMP-2, MMP-14, and TIMP-2.

CONCLUSIONS

CSC may increase HGF-mediated collagen degradation by affecting membrane-associated MMPs and TIMPs.

Crocetin inhibits invasiveness of MDA-MB-231 breast cancer cells via downregulation of matrix metalloproteinases

Crocetin is a carotenoid dicarboxylic acid which, in nature, is esterified with glucose or gentiobiose units forming the crocins, abundant components of saffron (a spice with many reputed medicinal uses). We have previously reported that saffron, crocins and crocetin inhibit breast cancer cell proliferation. In order to further study the effect of crocetin on breast cancer cells, we used the highly invasive MDA-MB-231 cells and measured the viability with the WST-1 assay and the invasiveness through a reconstituted basement membrane. After 24 h incubation, crocetin significantly inhibited not only proliferation but also invasion at 1 and 10 µM. Cancer invasiveness and metastasis are associated with the expression of matrix metalloproteinases (MMPs). In order to study the molecular changes of MMP expression that might accompany the observed crocetin effects, gene expression of MMPs was studied by RT-PCR, whereas protein expression and gelatinolytic activity were determined with Western blotting and zymography, respectively. The gene and protein expression of pro-MT1-MMP and pro-MT2-MMP were greatly attenuated by both crocetin and all- TRANS-retinoic acid (ATRA, used as control). Incubation with 10 µM crocetin for 24 h in serum-free conditions reduced pro-MMP-9 activity and pro-MMP-2/MMP-2 protein levels. When cultured in media with sera 2 and 5 %, crocetin at 10 μΜ also reduced gelatinase activity. The above findings show that crocetin, the main metabolite of crocins, inhibits MDA-MB-231 cell invasiveness via downregulation of MMP expression.

Matrix metalloproteinase-2 and -9 are induced differently by metal nanoparticles in human monocytes: The role of oxidative stress and protein tyrosine kinase activation

Recently, many studies have shown that nanoparticles can translocate from the lungs to the circulatory system. As a particulate foreign body, nanoparticles could induce host responses such as reactive oxygen species (ROS) generation, inflammatory cytokine and matrix metalloproteinase (MMP) release which play a major role in tissue destruction and remodeling. However, the direct effects of nanoparticles on leukocytes, especially monocytes, are still unclear. The objective of the present study was to compare the ability of Nano-Co and Nano-TiO(2) to cause alteration of transcription and activity of MMPs and to explore possible mechanisms. We hypothesized that non-toxic doses of some transition metal nanoparticles stimulate an imbalance of MMP/TIMP that cause MMP production that may contribute to their health effects. To test this hypothesis, U937 cells were treated with Nano-Co and Nano-TiO(2) and cytotoxic effects and ROS generation were measured. The alteration of MMP-2 and MMP-9 expression and activity of MMP-2 and MMP-9 after exposure to these metal nanoparticles were subsequently determined. To investigate the potential signaling pathways involved in the Nano-Co-induced MMP activation, the ROS scavengers or inhibitors, AP-1 inhibitor, and protein tyrosine kinase (PTK) inhibitors were also used to pre-treat U937 cells. Our results demonstrated that exposure of U937 cells to Nano-Co, but not to Nano-TiO(2), at a dose that does not cause cytotoxicity, resulted in ROS generation and up-regulation of MMP-2 and MMP-9 mRNA expression(..) Our results also showed dose- and time-related increases in pro-MMP-2 and pro-MMP-9 gelatinolytic activities in conditioned media after exposure of U937 cells to Nano-Co, but not to Nano-TiO(2). Nano-Co-induced pro-MMP-2 and pro-MMP-9 activity increases were inhibited by pre-treatment with ROS scavengers or inhibitors. We also demonstrated dose- and time-related decreases in tissue inhibitors of metalloproteinases 2 (TIMP-2) in U937 cells after exposure to Nano-Co, but not to Nano-TiO(2). However, neither Nano-Co nor Nano-TiO(2) exposure led to any transcriptional change of TIMP-1. The decrease of TIMP-2 after exposure to Nano-Co was also inhibited by pre-treatment with ROS scavengers or inhibitors. Our results also showed that pre-treatment of U937 cells with AP-1 inhibitor, curcumin, or the PTK specific inhibitor, herbimycin A or genistein, prior to exposure to Nano-Co, significantly abolished Nano-Co-induced pro-MMP-2 and-9 activity. Our results suggest that Nano-Co causes an imbalance between the expression and activity of MMPs and their inhibitors which is mediated by the AP-1 and tyrosine kinase pathways due to oxidative stress.

Imatinib inhibits colorectal cancer cell growth and suppresses stromal-induced growth stimulation, MT1-MMP expression and pro-MMP2 activation

Tumor progress depends on the proliferation of cancer cells, their interactions with stroma and the proteolytic action of enzymes. Colon cancer is c-kit positive and responsive to the specific tyrosine kinase inhibitor imatinib. We investigated the effect of imatinib on the proliferation of a panel of epithelial colon cancer cell lines in presence and absence of the antimetabolite 5-FU, and the effect of conditioned media (CM) derived from colon stromal fibroblasts with and without previous exposure to imatinib. The effects of imatinib on gene expression of MMPs and TIMPs were also studied. Imatinib effectively inhibited the proliferation of all cell lines, showing IC(50) from 0.3 to 3 microM. Its combination with 5-FU significantly enhances the growth inhibition of the highly tumourigenic HT-29 cells. CM derived from stromal fibroblasts induced the proliferation of the HT-29 cells; this stimulatory effect was abolished upon treatment with CM obtained after exposure of fibroblasts to imatinib. Gene expression of MT1-, MT2-MMP and MMP-7 was also inhibited depending on the cell line, whereas that of TIMP-2 was not affected. CM stimulated MT1-MMP protein expression by HT-29; this stimulatory effect was suppressed in the presence of imatinib. Activation of pro-MMP2 to MMP2 in culture medium of HT-29 treated with CM was increased and this activity was inhibited in presence of imatinib. The obtained data showed that imatinib is a powerful inhibitor of human colon cancer cell growth and effectively suppresses the stromal-induced stimulation of cancer cell growth and activation of proMMP2. Further studies are warranted to evaluate the in vivo effects.

Local and systemic pathophysiological alterations induced by a serine proteinase from the venom of the snake Bothrops jararacussu

The local and systemic pathophysiological alterations induced by BjussuSP-I, a thrombin-like serine proteinase from the venom of the snake Bothrops jararacussu, were assessed in mice. BjussuSP-I induced a mild edema but no local myonecrosis or hemorrhage. It did not induce any microvascular alteration in the cremaster muscle. Intramuscular injection of BjussuSP-I promoted an increase in the expression of proMMP-9, but it did not induce the activation of proMMP-2 or proMMP-9 synthesized in muscle tissue injected with a myotoxic phospholipase A(2) homolog. BjussuSP-I induced defibrin(ogen)ation upon intravenous and intramuscular injections, with reduction in plasma fibrinogen concentration and increments in the levels of fibrin degradation products and D-dimer. When compared with animals having normal coagulation, mice defibrin(ogen)ated by BjussuSP-I developed a slightly larger hemorrhagic lesion in the skin when injected with metalloproteinase BaP1. Intravenous injection of sublethal doses of BjussuSP-I promoted a series of behavioral and motor changes similar to those previously described for 'gyroxin', i.e. opisthotonus and a circular body movement along the longitudinal axis.

Androgenic-anabolic steroids associated with mechanical loading inhibit matrix metallopeptidase activity and affect the remodeling of the achilles tendon in rats

BACKGROUND

The indiscriminate use of anabolic-androgenic steroids has been shown to induce pathologic changes in the Achilles tendon in several situations.

PURPOSE

To study tendon remodeling in rats treated with anabolic-androgenic steroids combined with an exercise program.

STUDY DESIGN

Controlled laboratory study.

METHODS

Wistar rats were grouped as follows: sedentary (group I), injected with anabolic-androgenic steroids only (group II), trained only (group III), and trained and injected with anabolic-androgenic steroids (group IV). The trained groups performed jumps in water: 4 series of 10 jumps each, with an overload of 50% to 70% of the animal's body weight and a 30-second rest interval between series, for 6 weeks. Anabolic-androgenic steroids (5 mg/kg) were injected subcutaneously. Activity of matrix metallopeptidases, a marker for tendon remodeling, was analyzed in tissue extracts by zymography on gelatin-sodium dodecyl sulfate-polyacrylamide gel electrophoresis.

RESULTS

Morphological analyses of tendons showed that in group II, the most external layer that covers the tendon was thicker with aggregation of the collagen fibers, suggesting an increase in collagen synthesis. In group IV, an inflammatory infiltrate and fibrosis in tendons as well as a pronounced increase of the serum corticosterone level were observed. This training protocol upregulated matrix metallopeptidase activity, whereas anabolic-androgenic steroid treatment strongly inhibited this activity. The appearance of lytic bands with molecular masses of approximately 62 and 58 kDa suggests the activation of matrix metallopeptidase-2.

CONCLUSION

Anabolic-androgenic steroid treatment can impair tissue remodeling in the tendons of animals undergoing physical exercise by down-regulating matrix metallopeptidase activity, thus increasing the potential for tendon injury.

CLINICAL RELEVANCE

Since the AAS abuse is so widespread, a better comprehension of the pathological effects induced by these drugs may be helpful for the development of new forms of therapy of AAS-induced lesions.

Activation of gelatinolytic/collagenolytic activity in dentin by self-etching adhesives

Mild acids are known to activate dentin matrix metalloproteinase (MMPs). All self-etching dental adhesives are acidic (pH 1.5-2.7) and may activate dentin MMPs. The purpose of this study was to compare the ability of several all-in-one adhesives to activate gelatinolytic and collagenolytic activities in powdered mineralized dentin. Powdered dentin made from human teeth was mixed with all-in-one adhesives (Clearfil Tri-S Bond, G-Bond, Adper Prompt L-Pop) or a self-etching primer (Clearfil SE Bond primer) for varying times and then the reaction was stopped by extracting the adhesives using acetone. Fresh untreated mineralized dentin powder had a gelatinolytic activity of 3.31 +/- 0.39 relative fluorescent units (RFU) per mg dry weight (24 h) that increased, over storage time, to 87.5 RFU mg(-1) (24 h) after 6-8 wk. When fresh powder was treated with acidic Tri-S Bond, the gelatinolytic activity increased from 3.24 +/- 0.70 RFU mg(-1) to > 112.5 RFU mg(-1) (24 h) after 20 min and then remained unchanged. Monomers with lower pH values produced less activity. There was a significant, direct correlation between gelatinolytic activity and pH, with Tri-S giving the highest activity. Coating dentin powder with Tri-S resin prevented fluorescent substrates from gaining access to the enzyme, even though it activated the enzyme. In conclusion, self-etch adhesives may activate latent MMP and increase the activity to near-maximum levels and contribute to the degradation of resin-dentin bonds over time.

Human-grade purified collagenase for the treatment of experimental arterial chronic total occlusion

PURPOSE

Chronic total occlusions (CTO) remain a major limitation of percutaneous interventions. Procedural failure is usually due to the inability to cross the lesion with a guide wire. We have previously shown that local administration of a laboratory-grade collagenase followed by a 72-h waiting period may facilitate guide-wire crossing. The aim of the present study was to evaluate the efficacy and toxicity of a human-grade purified collagenase, suitable for clinical use, in facilitating guide-wire crossing in a rabbit model of femoral artery CTO.

METHODS AND RESULTS

A chronic total arterial occlusion was constructed in femoral arteries of New Zealand white rabbits. The local administration of purified collagenase solution (150 microg) via an over-the-wire balloon system was performed in 10 CTO. Guide-wire crossing was attempted after 24 h and was successful in all cases. Different doses (50-500 microg) were administered to an additional 17 rabbits to assess collagenase effects. Local subcutaneous bruising was observed at higher doses. Histological evaluation showed no damage to the arterial wall structure. Arterial extracts from collagenase-treated arteries showed increased MMP-2 and MMP-9 activities and higher levels of local MMP-1 and degraded collagen.

CONCLUSIONS

Local administration of a human-grade purified collagenase degrades collagen in CTO and is highly effective for the facilitation of guide-wire crossing in CTO.

Hyperforin inhibits MMP-9 secretion by B-CLL cells and microtubule formation by endothelial cells

We previously reported that hyperforin (HF), a natural phloroglucinol purified from Saint John's wort, can induce the apoptosis of leukemic cells from patients with B-cell lymphocytic leukemia (B-CLL) ex vivo. We show here that treatment of cultured B-CLL patients' cells with HF results in a marked inhibition of their capacity to secrete matrix metalloproteinase-9, an essential component in neo-angiogenesis through degradation of the extracellular matrix process. The phloroglucinol acts by decreasing the production of the latent 92 kDa pro-enzyme. The inhibitory effect of HF is associated with a decrease in VEGF release by the leukemic cells. Moreover, HF is found to prevent the formation of microtubules by human bone marrow endothelial cells cultured on Matrigel, evidencing its capacity to inhibit vessel formation. Our results show the antiangiogenesis activity of HF and strengthen its potential interest in the therapy of B-CLL.

Inhibition of human leukemia xenograft in nude mice by adenovirus-mediated tissue inhibitor of metalloproteinase-3

Considerable studies have demonstrated the pivotal roles of matrix metalloproteinases (MMPs) in leukemia dissemination and extramedullary infiltration. Tissue inhibitors of matrix metalloproteinases (TIMPs) are multifunctional proteins with MMPs inhibitory effects. However, little is known about the application of TIMPs in the treatment of leukemia. Here, we investigated the effects of TIMP-3 overexpression via adenoviral gene delivery on the in vitro growth and invasiveness of leukemic cells and the in vivo progress of K562-derived xenografts in nude mice. The in vitro invasiveness of K562 cells was markedly impaired by AdTIMP-3 infection. Moreover, TIMP-3 significantly inhibited K562-derived angiogenic factors-induced proliferation, migration and bFGF-induced tube formation of endothelial cells (ECs) in vitro, and reduced VEGF-induced gelatinases expression and activation in ECs. Although TIMP-3 overexpression had no direct effect on the growth of K562 cells in vitro, repeated intratumoral injection of AdTIMP-3 significantly inhibited the growth of K562 xenografts in nude mice. Furthermore, lower microvessel density, less vessel maturity and increased apoptosis were observed in AdTIMP-3-treated K562 xenografts, suggesting the importance of antiangiogenic action of TIMP-3. These data demonstrated the potential of applying AdTIMP-3 as an effective antiangiogenic adjuvant in the treatment of leukemia progression.

Inhibition of gelatinase B (matrix metalloproteinase-9) by dihydrolipoic acid

Alpha-lipoic acid (LA) is a disulphide-containing fatty acid that is absorbed from the diet and transported to tissues. Once it has been taken up by mammalian cells, LA is reduced to dihydrolipoic acid (DHLA), a vicinal dithiol, and rapidly effluxed into the extracellular milieu. We hypothesized that DHLA may be an effective inhibitor of human gelatinase B (GelB). Purified human GelB was incubated with 0 to 200 µmol/L DHLA, and residual enzyme activity was measured by HPLC using a fluorogenic substrate (matrix metalloproteinase substrate III). DHLA inhibited GelB in a dose-dependent fashion with an IC50of 20 µmol/L. Oxidation of DHLA resulted in a loss of DHLA's capacity to inhibit GelB. The DHLA-mediated inhibition of GelB was independent of the zinc concentration in the reaction buffer. DHLA had no inhibitory effect on gelatinase A. Zymographs of activated neutrophil lysates demonstrated that higher concentrations of DHLA also prevent the activation of GelB proenzyme. Bronchoalveolar lavage fluid from mice fed a diet enriched with LA showed significantly increased GelB inhibitory capacity (p = 0.0002 vs. regular diet). We conclude that DHLA can modulate neutrophil-derived GelB activity through direct inhibition of enzyme activity and by preventing the activation of GelB proenzyme.Key words: matrix metalloproteinases, pulmonary fibrosis, thiols, neutrophils, inflammation.

Matrilysin (MMP-7) promotes invasion of ovarian cancer cells by activation of progelatinase

Although matrilysin (MMP-7) is overexpressed in various malignancies, few studies have evaluated its role in epithelial ovarian cancer (EOC) invasion and metastasis. We report that the secretion of MMP-7 in EOC is stimulated significantly by vascular endothelial growth factor (VEGF) and interlukin-8 (IL-8). We also examined the in vivo expression of MMP-7 in EOC and its effects on the in vitro invasion and progelatinase activation. We report that MMP-7 is overexpressed in ovarian cancer cell lines and EOC surgical specimens. DOV13 cells incubated with active rhMMP-7 significantly increased cellular invasion and proMMP-2 activation. RhMMP-7 also showed the ability to activate proMMP-2 and proMMP-9 in immortalized ovarian epithelial cell (IOSE-29) conditioned medium. In addition, rhMMP-7 was able to activate progelatinase in a concentration-dependent manner in vitro. TIMP-2 or the generic MMP inhibitor-GM6001 inhibited both the activation of proMMP-2 and the increased invasion of DOV13 cells promoted by rhMMP-7. By incubation of MMP2-TIMP-2 complex with equal molar rhMMP-7, MMP-2 was dissociated from the complex and activated in a time-dependent manner, suggesting that TIMP-2 helps to keep the latency of MMP-2. TIMP-2 also showed inhibitory effects on the MMP-7 induced increase of gelatinolytic activity in DOV13 and IOSE-29 conditioned media. A strong co-localization of MMP-7 and MMP-2 was observed in DOV13 cells and ovarian carcinoma permanent tissue sections. These results indicate MMP-7 is overexpressed in malignant ovarian epithelium and suggest MMP-7 may facilitate tumor cell invasion in vivo partly through the induction of progelatinase activation.

The expression of core fucosylated E-cadherin in cancer cells and lung cancer patients: prognostic implications

It is well documented that the glycosylation of E-cadherin is correlated with cancer metastasis, but whether E-cadherin could be core fucosylated remains largely unknown. We found that E-cadherin was core fucosylated in highly metastatic lung cancer cells while absent in lowly metastatic lung cancer cells. Since alpha-1,6 Fucosyltransferase (alpha-1,6 FucT) is known to catalyze the reaction of core fucosylation, we investigated the biological function of core fucosylation on E-cadherin by alpha-1,6 FucT targeted RNAi and transfecting alpha-1,6 FucT expression vector. As a result, calcium dependent cell-cell adhesion mediated by E-cadherin was strengthened with the reduction of core fucosylation on E-cadherin after RNAi and was weakened with the elevated core fucosylation on E-cadherin after alpha-1,6 FucT over expression. Our data indicated that alpha-1,6 FucT could regulate E-cadherin mediated cell adhesion and thus play an important role in cancer development and progression. Computer modeling showed that core fucosylation on E-cadherin could significantly impair three-dimensional conformation of N-glycan on E-cadherin and produce conformational asymmetry so as to suppress the function of E-cadherin. Furthermore, the relationship between the expression of core fucosylated E-cadherin and clinicopathological background of lung cancer patients was explored in lung cancer tissue of patients. It turns out to demonstrate that core fucosylated E-cadherin could serve as a promising prognostic indicator for lung cancer patients.

Neurotoxic, hemorrhagic and proteolytic activities of Duvernoy's gland secretion from Venezuelan opisthoglyphous colubrid snakes in mice

Many colubrid snakes produce toxic oral secretions. We studied venom (Duvernoy's gland secretion) collected from Venezuelan opisthoglyphous (rear-fanged) colubrid snakes. Different proteins were present in Thamnodynastes stigilis Duvernoy's gland secretion and were characterized by 20% SDS-PAGE protein electrophoresis. The venom displayed proteolytic (gelatinase) activity that was partially purified on a chromatography ionic exchange mono Q2 column. We demonstrated hemorrhagic activity of Thamnodynastes stigilis Duvernoy's gland secretion on chicken embryos and mouse skin and peritoneum. Mice inoculated with Thamnodynastes stigilis Duvernoy's gland secretion presented signs of neurotoxicity. Thamnodynastes stigilis Duvernoy's gland secretion had proteolytic, hemorrhagic, and neurotoxic activities, not previously described in this species and identifies the presence of a new venomous colubrid in Venezuela.

Modulation of angiogenesis and progelatinase a by thrombin receptor mimetics and antagonists

The angiogenic action of thrombin has been shown to be mediated by activation of the thrombin receptor. In this report we studied the effects of SFLLR, an agonist of the activated thrombin receptor and thrombin receptor peptide and non peptide antagonists on angiogenesis in the chick chorioallantoic membrane (CAM) system. As antagonists were used the tripeptide FPR and non-peptide 1,4-disubstituted piperazine derivatives. The pentapeptide SFLLR, like thrombin, caused a marked stimulation of angiogenesis in the CAM. FPR and the piperazine derivatives caused suppression of angiogenesis and in combination with thrombin antagonized its angiogenic effect. Thrombin and SFLLR activated progelatinase A (MMP-2) in the culture medium of human umbilical cord endothelial cells (HUVECs). MMP-2 is involved in the early steps of angiogenesis leading to local dissolution of basement membrane collagen and migration of the activated endothelial cells. FPR and the piperazine derivatives inhibited the activation of this enzyme. They also antagonised the effects of both thrombin and SFLLR on MMP-2 activation. These results suggest that non-thrombogenic agonists or antagonists of the activated thrombin receptor can be used as modulators of angiogenesis.

A nonintrinsic regional basis for increased infrarenal aortic MMP-9 expression and activity

OBJECTIVE

This investigation was undertaken to determine whether intrinsic or regional factors at different anatomic sites of the aorta affect expression and activity of matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs).

METHODS

Aortas from Sprague-Dawley rats (n = 22) were divided into arch, descending thoracic, and infrarenal abdominal segments. Specimens were stimulated with interleukin-1beta (IL-1beta) (2 ng/mL) for 72 hours. In separate experiments, syngeneic aortic segments were transplanted from the thoracic or abdominal aortas of donor rats into the infrarenal aortic position of recipient rats (n = 12 each). At 4 weeks, aortas from rats who had received transplants were harvested, sectioned into arch, thoracic, and transplanted thoracic or transplanted abdominal segments, and stimulated with IL-1beta. Reverse transcriptase polymerase chain reaction, zymography, and reverse zymography were performed to assess MMP-9, MMP-2, and TIMP-1 in all aortic segments. Differences were assessed with analysis of variance (ANOVA) and post-hoc Tukey test.

RESULTS

In control rats, abdominal segments had significantly higher MMP-9 expression compared with arch and thoracic segments (P <.002). Total MMP-9 activity was also higher in abdominal segments (P <.02). In rats who received transplants, transplanted thoracic (P <.004) and transplanted abdominal (P <.05) segments demonstrated upregulation of MMP-9 expression, compared with control arch and thoracic segments. Zymography documented increased total MMP-9 activity in transplanted thoracic (P <.03) and transplanted abdominal (P <.04) segments versus arch and thoracic segments. No significant difference in MMP-9 expression was found between control abdominal, transplanted thoracic, or transplanted abdominal segments. No significant differences in MMP-2 or TIMP-1 expression or activity were demonstrated in either control or transplanted segments.

CONCLUSIONS

These data demonstrate that variations in aortic MMP-9 expression and activity result from regional factors affecting the aorta rather than intrinsic aortic wall differences. Increases in abdominal aortic MMP-9 may contribute to the predilection for aneurysm to develop in the infrarenal aorta.

Glycosaminoglycan-degrading enzymes in porcine aortic heart valves: implications for bioprosthetic heart valve degeneration

BACKGROUND AND AIM OF THE STUDY

Glutaraldehyde (GA)-fixed aortic valves used in heart valve replacement surgery have limited durability due to tissue degeneration and calcification. Despite their structural and functional importance, very little is known about the fate of glycosaminoglycans (GAGs) within the extracellular matrix of bioprosthetic heart valves. The study aim was to investigate the stability of GAGs in GA-fixed tissues and to identify enzymatic mechanisms that may be responsible for GAG degeneration.

METHODS

Porcine aortic valve cusps were fixed with GA and implanted subdermally in rats for 21 days. Fresh, fixed and explanted cusps were analyzed for GAG content by hexosamine determination, and GAG-degrading enzyme activity was evaluated using zymography. GAG classes in fresh cusps were also assessed by flurorophore-assisted carbohydrate electrophoresis. Fresh and GA-fixed cusps were also exposed in vitro to hyaluronidase and chondroitinase in order to test the susceptibility of cusp GAGs towards enzymatic degradation.

RESULTS

Native aortic cusps contained -3.5% GAGs by dry weight, consisting of hyaluronic acid, chondroitin sulfate and dermatan sulfate. Significantly lower GAG levels were found in aortic cusps after fixation with GA, and even lower levels were found after subdermal implantation in rats. GAG levels in GA-fixed cusps were also significantly reduced by in-vitro incubation with hyaluronidase and chondroitinase. Novel GAG-degrading enzymes were detected in considerable levels in native cusps, in lower levels in GA-fixed cusps and significantly increased levels after subdermal implantation of GA-fixed cusps.

CONCLUSION

The combined action of active GAG-degrading enzymes and the failure of GA to stabilize GAGs towards enzymatic digestion may contribute significantly to bioprosthetic heart valve degeneration and subsequent structural failure.

Anti-inflammatory effect of pre-elafin in lipopolysaccharide-induced acute lung inflammation

The aim of the present study was to evaluate the anti-inflammatory activity of pre-elafin, an elastase-specific inhibitor, in lipopolysaccharide (LPS)-induced acute lung inflammation. C57BL/6 mice were pre-treated intranasally with recombinant human pre-elafin or vehicle only. One hour later, they were instilled intranasally with LPS (2 microg/mouse). Animals were sacrificed 6 hours after LPS instillation and bronchoalveolar lavage (BAL) was performed with three 1-ml aliquots of saline. LPS induced a lung inflammation characterised by a 100-fold increase in BAL neutrophils compared to control animals (265.8 +/- 54.5 x 10(3) and 2.4 +/- 1.3 x 10(3) neutrophils/ml, respectively). Pre-elafin dose-dependently reduced the neutrophil influx in the lung alveolar spaces by up to 84%. No elastase activity was detectable in all BAL fluids tested. Pre-elafin also reduced significantly LPS-induced gelatinase activity, as shown by zymography, and BAL macrophage inflammatory protein-2 (MIP-2) and KC levels, two potent neutrophil attractants and activators. Moreover, pre-elafin also significantly reduced mRNA levels of the three members of the IL-1 ligand family, namely IL-1alpha, IL-1beta and IL-1 receptor antagonist (IL-1Ra), type II IL-1 receptor, and TNFalpha as assessed in whole lung tissue by RNase protection assay. Thus, pre-elafin may be considered as a potent anti-inflammatory mediator.

Regulation of matrix metalloproteinase-2 production by cytokines and pharmacological agents in human pulp cell cultures

Type IV matrix metalloproteinases (MMPs) are members of the family of MMPs and are thought to play an important role in degradation of extracellular components. Human pulp cells can secrete and produce these enzymes. Recent evidence shows that MMPs may play a role in pulpal inflammation. To date little is known regarding the regulation of MMPs in human pulp cell cultures. The purpose of this study was to determine the effects of cytokines (interleukin-1 and transforming growth factor-beta (TGF-beta), protein synthesis inhibitor cycloheximide (CD), and protein kinase C inhibitors (H7 and Go6976) on the secretion and production of MMPs by human pulp cell cultures using gelatin zymography. The main gelatinase secreted by human pulp cells migrated at 72 kDa and represented MMP-2. Minor gelatinolytic bands were also observed at 92 kDa regions that correspond to MMP-9. After an 8-day culture period TGF-beta, CD, H7, and Go6976 were found to depress MMP-2 production. The inhibition decreased in an order of CD > H7 > TGF-beta > Go6976. IL-1 was found to elevate MMP-2 production. Human pulp cells, however treated with either cytokines or pharmacological agents had no effect on the pattern of MMP-9 produced or secreted in either cell extracts or conditioned medium fractions. These observations suggest that the cytokines and pharmacological agents can regulate MMP-2 produced by human pulp cells. Inflammatory cytokines stimulate the production of elevated levels of MMP-2 and MMP-2 might play a role in pulpal inflammation. In addition agents that target protein synthesis or the protein kinase C pathway in human pulp cells inhibit MMP-2 production, and such inhibition may contribute to the pathogenesis of pulpal inflammation. Such inhibition might contribute to therapeutic efficacy.

Effects of dipeptide bestatin on Porphyromonas gingivalis and epithelial cells

BACKGROUND

Dipeptide bestatin has been previously reported to selectively inhibit the growth of Porphyromonas gingivalis. The aims of this study were to investigate the mechanism of action of bestatin and to evaluate its effect on epithelial cells.

METHODS

The inhibitory effect of bestatin on P. gingivalis was tested in vitro (culture medium) and in vivo (guinea pig model). Radiolabeled compounds were used to investigate the effect of bestatin on the uptake of amino acids and peptides. The cytotoxic effect of bestatin was evaluated using a keratinocyte cell line.

RESULTS

The growth inhibition of P. gingivalis by bestatin was concentration-dependent. Even at high concentrations, compounds possessing a chemical structure or an aminopeptidase inhibitor activity related to bestatin had no effect on growth of P. gingivalis. When injected in the presence of P. gingivalis, bestatin was able to prevent the development of a necrotic abscess in a guinea pig model. Data were obtained suggesting that bestatin does not act on proteinases of P. gingivalis. Rather, bestatin was found to inhibit the intracellular uptake of radioactivity from 14C-labeled amino acids or heat-denatured type I collagen. This was not observed with a spontaneous mutant of P. gingivalis, whose growth was not affected by bestatin. In the second part of the study, bestatin was found to have no effect on epithelial cell viability in culture at concentrations effective on P. gingivalis. In addition, bestatin did not show effects on epithelial cell migration or production of gelatinases.

CONCLUSIONS

This study suggests that bestatin selectively inhibits growth of P. gingivalis by affecting the intracellular uptake of amino acids and peptides, which serve as energy and nitrogen sources for this bacterial species. Bestatin has no cytotoxicity and may represent a therapeutic molecule for local treatment of P. gingivalis-associated periodontitis.

Activation of progelatinase A by mammalian legumain, a recently discovered cysteine proteinase

The activation of progelatinase A to gelatinase A requires cleavage of an asparaginyl bond to form the N-terminus of the mature enzyme. We have asked whether the activation can be mediated by legumain, the recently discovered lysosomal cysteine proteinase that is specific for hydrolysis of asparaginyl bonds. Addition of purified legumain to the concentrated conditioned medium from HT1080 cell culture that contained both progelatinases A and B caused the conversion of the 72 kDa progelatinase A to the 62 kDa form. The progelatinase B in the medium was unaffected. Incubation of recombinant progelatinase A with legumain resulted in an almost instantaneous activation as judged by the fluorometric assay with a specific gelatinase A substrate, Mca-Pro-Leu-Gly-Leu-Dpa-Ala-Arg-NH2. Legumain also activated progelatinase A when it was in complex with TIMP-2. Zymographic analysis and N-terminal sequencing revealed that legumain cleaved the 72 kDa progelatinase A at the bonds between Asn109-Tyr110 or Asn111-Phe112 to produce the 62 kDa mature enzyme, and that further cleavage at Asn430 also occurred to generate a 36 kDa active form. More 62 kDa gelatinase A was detected in cultures of C13 cells that over-expressed legumain than in those of the control HEK293 cells. We conclude that legumain is clearly capable of processing progelatinase A to the active enzyme in vitro and in cultured cells.

Interleukin-1 is a key regulator of matrix metalloproteinase-9 expression in human neurons in culture and following mouse brain trauma in vivo

An acute trauma to the CNS rapidly results in the upregulation of inflammatory cytokines that include interleukin-1 (IL-1). We report here that the levels of several matrix metalloproteinases (MMPs) are also elevated following a corticectomy trauma injury to the mouse CNS. The delayed upregulation of MMPs compared to that for IL-1 suggests the possibility that inflammatory cytokines regulate MMP production in CNS trauma. To resolve this, we developed a method to isolate and maintain highly enriched human fetal neurons or astrocytes in culture and examined the regulation by cytokines of the activity of a subgroup of MMPs, the gelatinases (MMP-2 and -9). While both neuronal and astrocytic cultures displayed comparable MMP-2 activity, as evidenced by gelatin zymography, levels of MMP-9 were proportionately higher in neurons compared to astrocytes. Of a variety of cytokines and growth factors tested in vitro, only IL-1beta was effective in increasing the neuronal expression of MMP-9. Finally, an IL-1 receptor antagonist attenuated the increase of neuronal MMP-9 in culture and abolished the injury-induced increase of MMP-9 in the mouse brain. These results implicate IL-1beta as a key regulator of neuronal MMP-9 in culture and of the elevation of MMP-9 that occurs following mouse CNS trauma.

Influence of homocysteine on matrix metalloproteinase-2: activation and activity

Increased levels of the physiological amino acid homocysteine (Hcy) are considered a risk factor for vascular disease. Hyperhomocysteinemia causes an intense remodelling of the extracellular matrix in arterial walls, particularly an elastolysis involving metalloproteinases. We investigated the activation of the latent elastolytic metalloproteinase proMMP-2 (72 kDa) by Hcy. Hcy was proved to exert a dual effect, activating proMMP-2 at low molar ratio (MR 10:1) and inhibiting active MMP2 at high molar ratio (MR > 1000:1). Methionine and the disulphide homocystine did not activate nor inhibit MMP-2, showing that the activation as well as the inhibition requires the thiol group to be free. The activation of proMMP-2 by Hcy is in accordance with the "cysteine-switch" mechanism, but occurs without further autoproteolysis of the enzyme molecule. In contrast with Hcy, the other physiological thiol compounds cysteine and reduced glutathione did not activate proMMP-2. These results suggest that the direct activation of proMMP2 by Hcy could be one of the mechanisms involved in the extracellular matrix deterioration in hyperhomocysteinemia-associated arteriosclerosis.

Marimastat inhibits elastin degradation and matrix metalloproteinase 2 activity in a model of aneurysm disease

BACKGROUND

Abdominal aortic aneurysms are characterized by degradation of the extracellular matrix, with a reduction in the elastin concentration of the arterial media. These changes have been linked to increased levels of endogenous metalloproteinases (MMPs) within the aorta, particularly MMP-2 and MMP-9. This provides a potential therapeutic target for pharmacological agents aimed at reducing the growth rate of small aneurysms. In this study, the ability of marimastat (an MMP inhibitor) to reduce matrix degradation was assessed in a previously described model of aneurysm disease.

METHODS

Porcine aortic segments (n = 12) were preincubated in exogenous pancreatic elastase for 24 h before culture in standard conditions for 13 days with marimastat 10(-5), 10(-6) and 10(-7) mol/l. Control segments were cultured both without marimastat and without elastase. At the termination of culture, MMPs were extracted from the tissue and quantified by substrate gel enzymography. The volume fractions of elastin and collagen were determined by stereological analysis of sections stained with Miller's elastin and van Gieson's stain.

RESULTS

Stereological analysis demonstrated preservation of elastin in aorta treated with marimastat at 10(-6) and 10(-5) mol/l; this was significant at the latter concentration (P = 0.007). This was accompanied by a significant reduction in active MMP-2 activity in the samples treated with marimastat 10(-5) mol/l (P < 0.01).

CONCLUSION

Marimastat significantly inhibited elastin degradation and active MMP-2 production within aortic organ cultures.

Regulation of gelatinases in microglia and astrocyte cell cultures by plant lectins

The effects of 25 recently discovered plant lectins on cell proliferation and enzyme release were compared to those of previously known lectins on rat microglia and astrocyte cell cultures. A dose-dependent proliferation of microglial cells, but not of astrocytes, was induced by seven lectins, whereas five lectins showed dose-dependent cytotoxicity on both microglia and astrocyte cell cultures. The activity of gelatinase B (MMP-9) was strongly increased in microglial cells by the aforementioned seven lectins, by concanavalin A, and by phytohemagglutinin (PHA-E4), whereas gelatinase A (MMP-2) remained at constitutive levels. The five cytotoxic lectins decreased the activity of gelatinase B in microglia and of gelatinase A in astrocytes, in a dose-dependent manner. The lectin wheat germ agglutinin induced a decrease in gelatinase B activity in microglia, but stimulated gelatinase A and B activity in astrocytes. These results indicate that lectins possess neuromodulatory effects that may motivate the study of their effects on central nervous system (CNS) function in vivo. This, in turn, may lead to better insight into whether lectin or lectin-like molecules can interact with glial cells, and whether they have a role in acute toxicity and in multifactorial diseases in which environmental factors may play a role.

Epidermal growth factor receptor function is necessary for normal craniofacial development and palate closure

Craniofacial malformations are among the most frequent congenital birth defects in humans; cleft palate, that is inadequate fusion of the palatal shelves, occurs with an annual incidence of 1 in 700 to 1 in 1,000 live births among individuals of European descent. The secondary palate arises as bilateral outgrowths from the maxillary processes, and its formation depends on the coordinated development of craniofacial structures including the Meckel's cartilage and the mandible. Cleft lip and palate syndromes in humans are associated with polymorphisms in the gene (TGFA) encoding transforming growth factor-alpha (TGF-alpha), an epidermal growth factor receptor (EGFR) ligand made by most epithelia. Here we have characterized craniofacial development in Egfr-deficient (Egfr-/-) mice. Newborn Egfr-/- mice have facial mediolateral defects including narrow, elongated snouts, underdeveloped lower jaw and a high incidence of cleft palate. Palatal shelf explants from Egfr-/- mice fused, but frequently had residual epithelium in the midline. In addition, morphogenesis of Meckel's cartilage was deficient in cultured mandibular processes from Egfr-/- embryos. The secretion of matrix metalloproteinases (MMPs) was diminished in Egfr-/- explants, consistent with the ability of EGF to increase MMP secretion and with the decreased MMP expression caused by inhibition of Egfr signalling in wild-type explants. Accordingly, inactivation of MMPs in wild-type explants phenocopied the defective morphology of Meckel's cartilage seen in Egfr-/- explants. Our results indicate that EGFR signalling is necessary for normal craniofacial development and that its role is mediated in part by its downstream targets, the MMPs, and may explain the genetic correlation of human cleft palate with polymorphisms in TGFA.

Diethyldithiocarbamate prolongs survival of mice in a lipopolysaccharide-induced endotoxic shock model: evidence for multiple mechanisms

It is now known that overproduction of nitric oxide (NO) by nitric oxide synthase (NOS) is an important contributing factor for the development of cardiovascular collapse and subsequent death in endotoxic shock. Diethyldithiocarbamate (DETC) is a molecular scavenger of NO and can inhibit overexpression of a number of cytokines during shock through inactivation of transcription factors such as nuclear factor (NF)-kappaB. Thus, DETC may be a useful adjunct in the therapy of endotoxic shock. In our study, we examined the effect of DETC on survival time in a murine model of severe endotoxic shock. Our results indicated that selected in vivo dosage regimens of DETC (intraperitoneal: at -2, -1, 3, 6, and 10 h or at -2, -1, 3, 6, 9, 12, 15, and 18 h relative to lipopolysaccharide administration, 180 mg/kg, at t = 0) in endotoxic mice were effective in increasing survival time when compared with untreated animals and DETC pretreatment was more effective than methylprednisolone (p<.05). DETC was shown to exert multiple beneficial mechanisms, including 1) a decrease in circulating NO, as determined by plasma nitrite/nitrate levels, 2) a reduction in plasma tumor necrosis factor-alpha after lipopolysaccharide induction, and 3) decreased expressions of metalloproteinases such as gelatinase A and B which may be responsible for cellular release of cytokines. These results indicate that DETC and its analogs may be useful in the treatment of endotoxic shock.

Thrombin rapidly and efficiently activates gelatinase A in human microvascular endothelial cells via a mechanism independent of active MT1 matrix metalloproteinase

Thrombin has been shown previously to activate gelatinase A in human umbilical vein endothelial cells. The activation is thought to be mediated by membrane-type 1 matrix metalloproteinase (MT1-MMP) on the cell surface, which generates the 62-kd intermediate and the 59-kd fully active forms. We used microvascular endothelial cells derived from human neonatal foreskin to investigate the mechanism of gelatinase A activation by thrombin. Gelatinase A was measured using zymography. Whereas activation by PMA generated both the 62-kd intermediate and the 59-kd fully active forms of gelatinase A after 24 hours, activation by thrombin produced only the 59-kd species rapidly (within 2 hours). Four findings indicate that MT1-MMP was not involved in thrombin-induced activation: (1) there was no up-regulation of MT1-MMP after 2 hours stimulation by thrombin, even though there was activation of gelatinase A; (2) the 62-kd intermediate species was never detected in response to thrombin; (3) tissue inhibitor of matrix metalloproteinase-2 completely prevented gelatinase A activation induced by PMA but not by thrombin; and (4) the metalloproteinase inhibitor 1,10-phenanthroline did not inhibit thrombin-induced activation. Together, these data demonstrate that activation of gelatinase A by thrombin is different from PMA and operating via a pathway independent of MT1-MMP. The ability of thrombin to rapidly and efficiently activate gelatinase A is likely to be a major contributing factor to its potent angiogenic activity.

Effects of tumour necrosis factor-alpha, interleukin-1 alpha, macrophage colony stimulating factor and transforming growth factor beta on trophoblastic matrix metalloproteinases

The aim of this study was to determine the effects of tumour necrosis factor alpha (TNF), interleukin-1 alpha (IL-1alpha), macrophage colony-stimulating factor (MCSF) and transforming growth factor beta (TGFbeta) on the secretion of matrix metalloproteinases (MMP), human chorionic gonadotrophin (HCG) and fetal fibronectin (fFN) by purified first trimester cytotrophoblastic cells (CTB) in vitro. CTB were obtained from legal abortions and cultured in vitro in the presence or absence of the different cytokines. Secreted gelatinases were analysed in the culture supernatants by zymography, by measurements of the total gelatinolytic activity and by enzyme immunoassays. HCG and fFN were measured by commercially available immunoassays. TNF increased the total gelatinolytic activity by increasing MMP-9 activity (P = 0.025-0.0177) but decreased MMP-2 activity (P < 0.03) and immunoreactivity (P < 0.05), fFN (P < 0.02) and HCG (P < 0.01). IL-1alpha significantly increased the secretion of fFN (P < 0.02), the activity (P < 0.02) and immunoreactivity (P < 0.05) of MMP-9 but had no effect on the other parameters. MCSF increased MMP-9 immunoreactivity (P < 0.05) and moderately decreased HCG. TGFbeta inhibited total gelatinolytic activity, MMP-9 activity and immunoreactivity, but was without effect on MMP-2 concentrations and activity. TGFbeta decreased HCG (P < 0.041) and increased fFN (P < 0.042). Our results indicate that TGFbeta, TNF and IL-1alpha are important regulators of trophoblastic MMP secretion.

Increased expression of matrix metalloproteinase-2 in the thickened intima of aged rats

-To characterize remodeling of elastic arteries with aging and to investigate its potential mechanisms, matrix metalloproteinase-2 (MMP-2), intracellular adhesive molecule-1 (ICAM-1), transforming growth factor-beta (TGF-beta), and fibronectin protein levels were measured in the aortas of young adult (6 months) and aged (30 months) Fischer 344XBN rats. At 30 versus 6 months, the thickness of the intima was 5-fold greater and contained marked increases in TGF-beta and ICAM-1, and fibronectin expression was enhanced throughout the aortic wall. Total MMP-2 protein (Western blot) of 30-month-old rats was increased 8-fold over that of 6-month-old rats (0.166+/-0.032 versus 0.020+/-0.006; P<0.01), and staining and activity were regionally localized to the intima, often near breaks in the internal elastic membrane and lamellae. Early passage, explanted smooth muscle cells (SMC) from aged aorta secreted more MMP-2 than those from young aorta; while basal MMP-2 production did not differ with age, after stimulation with cytokines (interleukin-1, tumor necrosis factor-alpha, or TGF-beta, 10 ng/mL each for 24 hours), MMP-2 production in SMC from 30-month-old rats increased to levels greater than those in 6-month-old rats. Thus, enhanced expression of TGF-beta, MMP-2, and ICAM-1 in the thickened vascular intima of aged rats may in part be produced by exaggerated SMC responses to cytokines and may have potential roles in intimal remodeling with aging.

Excessive synthesis of matrix metalloproteinases in exocrine tissues of NOD mouse models for Sjögren's syndrome

OBJECTIVE

Matrix metalloproteinases (MMP) and their substrates, components of the extracellular matrix, regulate environmental signals for cellular differentiation and tissue function. Changes in the levels of these enzymes may influence cell survival as well as pathology involving ectopic apoptosis. Using the non-obese diabetic (NOD) mouse model for Sjögren's syndrome, we evaluated the synthesis and expression of MMP in the exocrine target tissues of autoimmunity.

METHODS

NOD, immunodeficient NOD-scid, and nondiabetic NOD.B10.H2b mice were evaluated for MMP activity in their saliva and exocrine gland lysates by gelatin zymography and reverse transcriptase-polymerase chain reaction (RT-PCR). In addition, changes in protein content of saliva and gland lysates were determined by specific Western blot and by enzymatic activity of amylase and cysteine proteases. Mice continuously treated with the MMP inhibitor GM6001 were evaluated from 7 to 20 weeks of age for the contribution of MMP activity to development of these hallmark biochemical markers of Sjogren's syndrome-like disease of NOD mice.

RESULTS

Gelatin zymography of whole saliva and gland lysates indicated the presence of increased proteolytic activity, corresponding to proteins with a molecular mass ranging from 50 to 95 kDa, in the saliva of older (> 20 weeks of age) NOD mice as well as NOD.B10.H2b and NOD-scid mice compared to BALB/c controls. Elevated steady state levels of mRNA transcripts for the gelatinases MMP-2 and MMP-9 were detected in total RNA extracted from parotid and submandibular glands by RT-PCR. Despite prophylactic injection of the broad spectrum MMP inhibitor GM6001 into mice beginning at 7 weeks of age and continuing to 20 weeks, development of the autoimmune exocrinopathy was neither stopped nor retarded.

CONCLUSION

These observations suggest that excessive MMP activity is associated with autoimmune Sjögren's syndrome-like disease in NOD mice. However, a possible contribution by increased MMP activity in initiation and progression of this autoimmune disease is yet to be elucidated.

Soluble latent membrane-type 1 matrix metalloprotease secreted by human mesangial cells is activated by urokinase

BACKGROUND

Matrix metalloprotease 2 (MMP2) is secreted in a latent inactive form (pro-MMP2) that is activated on the cell surface by a membrane-type 1 MMP (MT1-MMP) in the presence of the tissue inhibitor of MMP (TIMP2). In spite of evidence for the synthesis of MT1-MMP shown by immunoblotting, immunocytochemistry and RT-PCR, and of TIMP2, MMP2 was found exclusively in a latent form in human mesangial cells (HMC) serum-free culture medium.

METHODS AND RESULTS

On purified membranes of HMC, MT1-MMP was found in a 63 kD latent form and as a faint band of 55 kD. The 55 kD band was also present in the ultracentrifuged conditioned medium and likely represented MT1-MMP cleaved from its transmembrane domain, since Northern blot analysis showed only one transcription product. The addition of urokinase plasminogen activator (uPA, 100 nM) to HMC membranes induced the activation of pro-MMP2 via the activation of latent membrane-associated MT1-MMP as reflected by the cleavage of the 63 and 55 kD forms. In addition, when the conditioned medium was successively incubated with uPA and alpha 2-macroglobulin and analyzed by immunoblotting, MT1-MMP decreased, indicating that the soluble MT1-MMP was in a latent form and was activated by uPA.

CONCLUSION

Our results provide the first evidence, to our knowledge, of the existence of a soluble latent form of MT1-MMP secreted by primary human cells in culture, confirming that MT1-MMP is an ectoenzyme, and show that uPA can regulate MT1-MMP activity in a soluble phase.

A 70-kDa amino-terminal fibronectin fragment supports gelatin binding to macrophages and decreases gelatinase activity

We previously reported that a macrophage response that increased binding to 125I-radiolabeled soluble denatured collagen (gelatin) was induced by preincubation of macrophage with a 70-kDa amino-terminal fibronectin fragment and soluble nonlabeled gelatin [S. F. Penc, F. A. Blumenstock, J. E. Kaplan (1995) J. Leukoc. Biol. 58, 501-509]. We now report that neither protein synthesis nor recycling of receptors between the cell surface and interior were required for this response. However, removal of cell surface components with trypsin demonstrated that induced gelatin binding required native cell surface constituents. It was found that in the presence of the 70-kDa fibronectin fragment and gelatin, matrix metalloprotease-2 (MMP-2) and matrix metalloprotease-9 (MMP-9) activity in the cell layers was significantly decreased or undetectable, respectively. Similar levels of increased gelatin binding could be reproduced after inhibition of matrix-degrading metalloprotease activity with 1'10-phenanthroline. These results demonstrate that a macrophage specific response that decreased gelatinase activity and increased gelatin binding was initiated by interaction with a 70-kDa fibronectin fragment and gelatin.

Differential regulation of matrix metalloproteinases and their inhibitors in human glomerular epithelial cells in vitro

The present study examines the effect of transforming growth factor-beta1 (TGF-beta1) and interleukin-1beta (IL-1beta) on the regulation of gelatinase A, gelatinase B, tissue inhibitor of metalloproteinase-I (TIMP-I) and TIMP-II in human glomerular epithelial cells (GEC). The addition of TGF-beta1 resulted in the increased production and secretion of both gelatinase A (72-kD type IV collagenase) and gelatinase B (92-kD type IV collagenase), in a dose- and time-dependent manner. In contrast, the addition of IL-1beta to GEC resulted in the stimulation of secretion of gelatinase B but not gelatinase A. When the secretion of the regulatory inhibitors was examined, IL-1beta or TGF-beta1 both resulted in an increased secretion of TIMP-I, whereas the secretion of TIMP-II was downregulated. Such results demonstrate an independent and opposite regulation of the enzymes and their inhibitors. Of particular interest was the observation of the differential regulation of gelatinase A and its specific inhibitor TIMP-II (which binds to the latent form of this enzyme) in response to TGF-beta1. These results for the first time indicate that in human GEC, matrix metalloproteinases (MMP), as well as their specific inhibitors, are independently regulated by different cytokines. MMP and their regulatory tissue inhibitors (TIMP) play an important role in tissue remodeling. The results of the present study serve to emphasize both the complex regulation of matrix metabolism in the glomerulus and the potential pathologic role of an imbalance between the proteinases and their inhibitors in various forms of glomerular disease.

Tissue inhibitor of metalloproteinase-2 protection of matrix metalloproteinase-2 from degradation by plasmin is reversed by divalent cation chelator EDTA and the bisphosphonate alendronate

The degradation of tissue inhibitor of metalloproteinase (TIMP)-free matrix metalloproteinase (MMP)-2 to proteolytically inactive fragments by plasmin was inhibited in equimolar mixtures of purified TIMP-2 and TIMP-free MMP-2 and was not observed in purified MMP-2-TIMP-2 complexes. Divalent cation chelators EDTA and sodium Alendronate did not inhibit plasmin degradation of TIMP-free MMP-2 but reversed the ability of TIMP-2 to protect MMP-2 from degradation by plasmin. Our data confirm a role for plasmin in the clearance of TIMP-free MMP-2, identify a pivotal role for TIMP-2 in regulating MMP-2 longevity in plasmin-containing environments, and highlight a novel therapeutic use for chelators of divalent cations, including the bisphosphonate Alendronate, in the reversal of TIMP-2 protection of MMP-2 from degradation by plasmin. We propose that these observations are relevant to pathologies that are dependent upon plasmin and MMP-2 activity (e.g., tumor invasion and metastasis).

Induction of matrix metalloproteinase expression in human macrophages by orthopaedic particulate debris in vitro

We exposed human macrophages isolated from the peripheral blood of healthy donors to metal and bone-cement particles from 0.2 to 10 microm in size. Zymography showed that macrophages exposed to titanium alloy and polymethylmethacrylate (PMMA) particles released a 92- and 72-kDa gelatinase in a dose- and time-dependent manner. Western immunoblotting confirmed that the 92- and 72-kDa gelatinolytic activities corresponded to matrix metalloproteinase-9 and matrix metalloproteinase-2 (MMP-9, MMP-2), respectively. Western immunoblotting also indicated that titanium alloy and PMMA particles increased the release of MMP-1. Northern blotting showed elevated mRNA signal levels for MMP-1, MMP-2, and MMP-9 after exposure to both types of particle. Collagenolytic activity also increased in the macrophage culture medium in response to both types of particle. Our findings support the hypothesis that macrophages release MMPs in proportion to the amount of particulate debris within periprosthetic tissues.

In vitro expression of MMP-2 and MMP-9 in glioma cells following exposure to inflammatory mediators

Progression of glioma is associated with local degenerative processes which are attributed to the activity of gelatinases. As glioma cells are candidate for secretion of these enzymes, we have studied in vitro the potential of cytokines (interleukin-1alpha (IL-1), tumor necrosis factor-alpha (TNFalpha) and transforming growth factor-beta (TGFbeta2)) to regulate the expression of gelatinase A and B (Gels A and B, respectively) in two glioma cells of human (A172) and rat origin (C6). We showed that IL-1 and TNFalpha both induced gene expression and protein secretion of Gel B in both cell lines, as revealed by RT-PCR and gelatin zymography, respectively. In C6 cells, TNFalpha had no effect on Gel A constitutive expression while IL-1 increased its production, but only at high doses. We have also demonstrated that TGFbeta2 inhibited both IL-1- or TNFalpha-induced gene expression and Gel B production in a dose-dependent manner but had no effect on Gel A secretion. The effect of TGFbeta2 on Gel B secretion was reversed by phorbol myristate acetate (PMA). Taken together, these data suggest that IL-1, TNFalpha and TGFbeta2 tightly regulate Gel B secretion in glioma cells, an enzyme which is believed to play an important role in the local invasion of brain tissue by tumor cells.

Inhibitory effects of malotilate on invasion and metastasis of rat mammary carcinoma cells by modifying the functions of vascular endothelial cells

Malotilate (diisopropyl,1,3-dithiol-2-ylidenemalonate, MT) is clinically used as a hepatoprotective agent. Because we noticed that MT induced the differentiation of cultured vascular endothelial cells, we have examined its effects on lung metastasis of the highly metastatic rat mammary carcinoma c-SST-2. MT was orally administered to syngeneic SHR rats from 7 days before or after s.c. inoculation of c-SST-2 cells to the end of the experiments. In the MT-treated rats, pulmonary metastasis was markedly suppressed compared with the non-treated rats. In the rats treated with MT for 19 days after i.v. inoculation of c-SST-2 cells, lung metastasis was also significantly suppressed. An in vitro invasion assay using a rat lung endothelial (RLE) cell monolayer revealed that pretreatment of the RLE cells with MT, but not c-SST-2 cells, significantly reduced the invasion of the RLE monolayer by c-SST-2 cells. An in vitro vascular permeability assay demonstrated that MT prevented the increase in permeability of the RLE monolayer by serum starvation. On the other hand, in vivo and in vitro growth, gelatinase production and adhesion to the RLE cell monolayer of c-SST-2 cells were not affected by MT treatment. These findings suggest that MT suppressed tumour metastasis by intensifying the cell-to-cell contact of endothelial cells, thus preventing tumour cells from invading vascular endothelium.

Alpha-melanocyte-stimulating hormone blocks invasion of reconstituted basement membrane (Matrigel) by murine B16 melanoma cells

We have examined the effect of alpha-melanocyte-stimulating hormone (alpha-MSH) on invasive ability of murine melanoma cell lines with different metastatic potential in a Matrigel invasion assay. alpha-MSH potently blocked the invasion of B16-BL6 cells with highly metastatic potential in a concentration-dependent manner, whereas it was less effective in inhibiting the invasion of weakly metastatic B16-F1 cells. Pretreatment of B16-BL6 cells with alpha-MSH resulted in a decrease of the adhesiveness to fibronectin and laminin substrates in a time-dependent fashion. As assessed by zymographic analysis, alpha-MSH partially inhibited the production of matrix metalloproteinase (MMP)-2 and -9 from both cell lines to a similar degree without affecting the degradative activity of these MMPs. alpha-MSH was more potent in inhibiting the migration of B16-BL6 cells towards both fibronectin- and laminin-coated substrates than that of B16-F1 cells. The growth and morphology of B16-BL6 cells were not changed after a 7-day incubation with alpha-MSH. The number of lung tumor colonies markedly decreased when B16-BL6 cells were coinjected intravenously with 10(-6) M alpha-MSH. However, alpha-MSH had no effect on the experimental lung metastases by B16-F1 cells. These results suggest that alpha-MSH suppressed the invasive and metastatic properties of B16 melanoma cells, and the degree of inhibition was associated with metastatic potential of B16 melanoma cells.

IL-10 inhibition of human prostate PC-3 ML cell metastases in SCID mice: IL-10 stimulation of TIMP-1 and inhibition of MMP-2/MMP-9 expression

The molecular mechanism by which IL-10 inhibits metastases was examined using a SCID mouse model. Human PC-3 ML subclones normally metastasize to the lumbar vertebrae (approximately 70% mice injected, n = 14/20) following intravenous injection in severe combined immunodeficient (SCID) mice. IL-10 treatment of the PC-3 ML cells (15 ng/ml for 36 h) and the SCID mice (0.03 mg/kg/day for 30 days) reduced the number of metastases to 5% of the mice (n = 1/20). More importantly, following discontinuation of IL-10 treatment on day 30, the mice remained tumor-free and mouse survival rates increased dramatically (from < 30% in untreated mice) to about 85% in IL-10-treated mice. IL-10 did not appear to alter the growth rates or colony-forming ability of the PC-3 ML cells in vitro. Likewise, the growth of subcutaneous tumors and established bone marrow metastases was not inhibited by IL-10 treatment of the SCID mice. However IL-10 may inhibit the production of matrix metalloproteases (MMP) and prevent the establishment of metastasis. We therefore examined the influence of IL-10 on PC-3 ML production of MMP-2/MMP-9 and the tissue inhibitors of metalloproteinases (TIMP-1/2). Enzyme-linked immunosandwich assays (ELISAs) revealed that IL-10 (15 ng/ml for 36 h) treatment of the PC-3 ML cells down-regulated MMP-2 and MMP-9 while up-regulating TIMP-1 (not TIMP-2) expression. Likewise, IL-10-treated mice exhibited similar changes in TIMP-1 and MMP-2/MMP-9 expression. The IL-10 effects were blocked by IL-10 receptor antibodies. In comparison to IL-10, IL-4 failed to influence metastasis or the expression of TIMP-1, TIMP-2, MMP-2 and MMP-9 by PC-3 ML cells. We suggest that IL-10-regulated increases in the molar ratio of TIMP-1/MMP-9 and TIMP-2/MMP-2 might inhibit processes critical to the establishment of bone marrow metastasis.

Nitric oxide mediates interleukin-1-induced gene expression of matrix metalloproteinases and basic fibroblast growth factor in cultured rabbit articular chondrocytes

We recently reported that nitric oxide (NO), which is produced by chondrocytes treated with interleukin-1beta (IL-1), releases basic fibroblast growth factor (bFGF) stored in the matrix of articular chondrocytes. To clarify the mechanism of the IL-1-induced bFGF release, we investigated the production and gene expression of bFGF, matrix metalloproteinases (MMPs), syndecan 3, and inducible NO synthase (iNOS) by IL-1-treated rabbit articular chondrocytes. IL-1 stimulated not only the release of bFGF but also the production of it. Gelatin and casein zymography revealed that IL-1 stimulated the production of not only MMP-9 but also MMP-3. The increase in the production of these MMPs preceded the IL-1-stimulated bFGF release. An MMP inhibitor partially suppressed the release of bFGF, indicating that matrix degradation is at least partially involved in the IL-1-stimulated bFGF release even if increased production of bFGF is related to the release. IL-1 sequentially stimulated mRNA expression of iNOS, membrane type 1-MMP, MMP-9 and -3, and bFGF, in that order. NG-Monomethyl-L-arginine, an inhibitor of NO production, inhibited gene expression of MMP-9 and bFGF. These findings suggest that elevation of the NO level via iNOS mRNA expression stimulated by IL-1 mediates gene expression and production of MMPs and bFGF, resulting in the release of bFGF, and also reveal molecular mechanisms implicating the degradation of articular cartilage followed by angiogenesis in the synovium in arthritic joints.

Oral administration of doxycycline reduces collagenase and gelatinase activities in extracts of human osteoarthritic cartilage

OBJECTIVE

To determine whether oral administration of doxycycline in clinically relevant doses will suppress activities of collagenase and gelatinase in extracts of human osteoarthritic (OA) cartilage.

METHODS

Femoral heads were obtained from 21 patients undergoing arthroplasty for endstage hip OA. Activities of collagenase and gelatinase were measured in extracts of the OA cartilage from patients who received doxycycline, 100 mg bid or qam for 5 days before surgery (n = 5 and n = 6, respectively), 200 mg as a single dose 3 days before surgery (n = 4); or no doxycycline (n = 6).

RESULTS

Five days of doxycycline treatment, in a dose of either 100 mg bid or 100 mg qam, inhibited gelatinase activity in the cartilage extracts (p = 0.003, 0.008, respectively). The bid dose also inhibited collagenase activity (p = 0.002), but inhibition of collagenase with 100 mg qam did not quite reach statistical significance (p = 0.055), in comparison with the values for the untreated OA controls. The single 200 mg dose, given 3 days before procurement of the cartilage, was ineffective in inhibiting metalloproteinase activity.

CONCLUSION

Oral administration of doxycycline significantly inhibited collagenase and gelatinase activity in human OA cartilage. The effective dose is likely to be well tolerated during chronic administration, e.g., in a clinical trial to assess the potential of the drug to modify cartilage breakdown in OA.

Calmodulin antagonists increase the expression of membrane-type-1 matrix metalloproteinase in human uterine cervical fibroblasts

The treatment of human uterine cervical fibroblasts with concanavalin A (ConA), or a specific calmodulin antagonist, N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W-7) or trifluoperazine resulted in accumulation of an active form of matrix metalloproteinase 2 (MMP-2, gelatinase A). In contrast, N-(6-aminohexyl)-1-naphthalenesulfonamide (W-5), a weaker antagonist of calmodulin, did not modulate the activation of proMMP-2. The activation of proMMP-2 was confirmed by the enhanced activity on gelatin and the conversion of proMMP-2 to a 62-kDa form by zymography and western blotting. The plasma membrane, but not the conditioned medium, of the W-7- or trifluoperazine-treated cells activated proMMP-2; this activation was blocked by membrane-type-1 MMP (MT1-MMP) antibody and EDTA. The plasma membrane from trifluoperazine- or ConA-treated cells contained MT1-MMP and tissue inhibitor of metalloproteinases 2. Both trifluoperazine treatment and ConA treatment increased the steady-state levels of MT1-MMP mRNA and proMMP-2 mRNA. These results, together with our previous observations on the production of proMMP-1 (interstitial procollagenase) and proMMP-3 (prostromelysin 1) [Ito, A., Sato, T., Ojima, Y., Chen, L.-C., Nagase, H. & Mori, Y. (1991) J. Biol. Chem. 266, 13598-13601], suggest that calmodulin negatively regulates the matrix turnover by suppressing the production of a number of proMMPs including proMMP-1, proMMP-3 and MT1-MMP, and the activation of proMMP-2 in human uterine cervical fibroblasts.

Cytokines stimulate matrix metalloproteinase production by human pulp cells during long-term culture

Interleukin-1 and tumor necrosis factor-alpha are inflammatory cytokines that are known to be potent stimulators of mineralized tissue resorption. One of the mechanisms by which these cytokines induce this loss is through the stimulation of matrix metalloproteinase (MMP) production and secretion by the host cells present at the inflammatory site. We have previously shown that these cytokines have little effect on MMP production by human pulp cells in short-term culture (24 to 48 h). In this study, we examined the production of MMPs by human pulp cells in the presence and absence of interleukin-1 and tumor necrosis factor-alpha in long-term cultures (2 to 16 days) using substrate gel zymography. The major band present in all samples examined migrated at 68 kDa, corresponding to the migration pattern of MMP-2, whereas a minor band migrated at 90 kDa, corresponding to the migration pattern of MMP-9. In the presence of cytokines, elevated levels of MMP-2 and MMP-9 were apparent at days 9 through 16. In addition, a band migrating at 110 kDa was present. This study demonstrates that cytokines stimulate the production of elevated levels of MMPs by human pulp cells in long-term cultures and that these MMPs may play a role in pulpal inflammation.

Retinoic acid treatment elevates matrix metalloproteinase-2 protein and mRNA levels in avian growth plate chondrocyte cultures

Matrix metalloproteinases (MMPs) play a crucial role in tissue remodeling. In growth plate (GP) cartilage, extensive remodeling occurs at the calcification front. To study the potential involvement of MMPs in retinoic acid (RA) regulation of skeletal development, we studied the effect of all-trans-RA on MMPs levels in mineralizing chicken epiphyseal chondrocyte primary cultures. When treated for 4 day periods on days 10 and 17, RA increased levels of an approximately 70 kDa gelatinase activity. The N-terminal sequence of the first 20 amino acid residues of the purified enzyme was identical to that deduced from chicken MMP-2 cDNA. Time-course studies indicated that RA elevated MMP-2 activity levels in the cultures within 16 h. This increase was inhibited by cycloheximide and was enhanced by forskolin. The increase in MMP-2 activity induced by RA was accompanied by an increase in MMP-2 mRNA levels and was abolished by treatment with cycloheximide. This upregulation of MMP levels by RA in GP chondrocytes is consistent with its effects on osteoblasts and osteosarcoma cells and opposite its inhibitory effects on fibroblasts and endothelial cells. It may well be related to the breakdown of the extracellular matrix in the GP and would be governed by the availability of RA at the calcification front where extensive vascularization also occurs.

EGF and IL-1 alpha modulate the release of collagenase, gelatinase and TIMP-1 as well as the release of calcium by rabbit calvarial bone explants

Matrix metalloproteinases (MMPs), among which is collagenase (MMP-1), are likely to be involved in various steps of the bone resorption process. As both production of these enzymes and bone resorption appear to be mediated by cytokines, we investigated the effects of two cytokines, IL-1 alpha and EGF, on the release of collagenase, gelatinase A (MMP-2), gelatinase B (MMP-9), TIMP-1 and calcium by rabbit calvariae. It was found that all these parameters increased under the influence of these cytokines. The release of calcium--used as a parameter of bone resorption--was highest in the combined presence of the cytokines. Although the absolute and relative enhancement by a combination of IL-1 alpha and EGF was most pronounced for collagenase (7-fold), both gelatinase A (5-fold) and gelatinase B (1.5-fold) had increased simultaneously. Calvariae produced a high level of MMP inhibitor (TIMP-1), especially under the influence of the cytokines; periosteum released little inhibitor. It is concluded that IL-1 alpha and EGF are likely to play a modulating role in the process of bone resorption.

Increased expression of activated matrix metalloproteinase-2 by human endothelial cells after sublethal H2O2 exposure

Basement membranes form a boundary between intravascular and extravascular compartments that is remodeled by matrix metalloproteinases (MMP) expressed by endothelial cells. These cells are at risk of exposure to reactive oxygen intermediates generated as a consequence of interactions with drugs, x-radiation, activated neutrophils, or cancer cells. Herein we have investigated the hypothesis that endothelial cells alter their expression of MMP after sublethel exposure to H2O2 and that this leads to degradation of adjacent basement membranes. Cultured human umbilical vein endothelial cells were treated with concentrations of H2O2 ranging from 1.5 to 32 microM or with 2 x 10(-6)M phorbol myristate acetate (PMA). After 24 hours, the cells were placed into serum-free medium for an additional 24 hours. This conditioned medium or cell lysates were studied by matrix degradation assays, gelatin zymography, immunoblots, and Northern analysis. H2O2-treated or PMA-treated cells, or their serum-free conditioned medium, caused a 2-fold increase in degradation of [3H]-proline-labeled endothelial basement membranes or purified type IV collagen compared to untreated cells. Endothelial cells constitutively expressed gelatinases at Mr 96,000 and 72,000, consistent with MMP-9 and inactive MMP-2. H2O2 exposure caused increased expression of these MMP and appearance of Mr 64,000 to 66,000 gelatinases corresponding to activated MMP-2. In cell lysates, H2O2 or PMA treatment led to increased expression of membrane-type MMP-1, an activator of latent MMP-2. The results suggest that oxidants such as H2O2 may stimulate MMP expression and influence the remodeling of vascular basement membranes by endothelial cells.

Characterization of a metalloproteinase: a late stage specific gelatinase activity in the sea urchin embryo

We have partially purified and characterized an 87 kDa gelatinase activity expressed in later stage sea urchin embryos. Cleavage activity was specific for gelatin and no cleavage of sea urchin peristome type I collagen, bovine serum albumin or casein was detected. Magnesium and Zn2+ inhibited the gelatinase and Ca2+ protected against inhibition. Ethylenediamine tetracetic acid, ethylenebisoxyethylenenitriol tetraacetic acid and 1,10-phenanthroline were inhibitory, suggesting that the gelatinase is a Ca(2+)- and Zn(2+)-dependent metalloproteinase. No inhibition was detected with serine or cysteine protease inhibitors and the vertebrate matrix metalloproteinase (MMP) inhibitor, Batimastat, was also ineffective. The vertebrate MMP activator p-aminophenylmercuric acetate was without effect. These results allow us to identify both similarities and differences between echinoderm and vertebrate gelatinases.

Effect of cisplatin and BCNU on MMP-2 levels in human glioblastoma cell lines in vitro

Matrix metalloproteinases (MMPs) play an important role in various physiological and pathological conditions such as tissue remodeling, and cancer cell invasion and metastasis. The aim of this study was to determine the effect of the antitumor compounds cis-dichlorodiammine platinum (ii) (cisplatin) and 1, 3 bis (2-chloroethyl)-1-nitrosourea (BCNU) on 72-kDa type IV collagenase activity (MMP-2) in human gliomas. Human glioblastoma cell lines were treated with cisplatin (25 microM), and BCNU (50 microM), and the levels of MMP-2 were estimated in serum-free conditioned medium and in cell extracts at different time intervals. Gelatin zymography revealed increased levels of MMP-2 in serum-free conditioned medium and in cell extracts of untreated glioblastoma cell cultures during a 72-h period. In contrast, MMP-2 levels were significantly decreased in cisplatin-treated cells both in conditioned medium and cell extracts. However, no significant changes of MMP-2 levels were noted in BCNU-treated cells. Quantitative analysis of MMP-2 enzyme activity by densitometry and amount of MMP-2 protein by ELISA showed significantly decreased levels of MMP-2 in cisplatin-treated cells compared to BCNU and untreated glioblastoma cells. The results indicate that decreased levels of MMP-2 might represent an additional mechanism by which cisplatin provides its antineoplastic effects.

Collagen degradation induced by the combination of IL-1alpha and plasminogen in rabbit articular cartilage explant culture

To investigate the effect of plasminogen on cartilage catabolism, we assessed collagen degradation in rabbit articular cartilage explants treated with or without plasminogen and interleukin-1alpha (IL-1alpha). The combination of IL-1 alpha and plasminogen induced rapid collagen degradation, amounting to more than 60% of the total collagen by day 7, while neither IL-1alpha nor plasminogen alone had any effect. To examine the mechanism of collagen degradation induced by IL-1alpha and plasminogen, the matrix metalloproteinases (MMPs) in the culture supernatants were examined by ELISA, Western blotting and gelatin zymography. We found that the treatment with IL-1alpha induced MMP-1, MMP-3, and MMP-9. In addition, plasminogen converted the pro form of MMPs into the active form. Both a tissue inhibitor of metalloproteinases-1 (TIMP-1) and a synthetic hydroxamate MMP inhibitor prevented this collagen release. These results suggest that plasminogen causes collagen degradation via activation of MMPs induced by IL-1alpha.