TNF-alpha and IL-1beta selectively induce expression of 92-kDa gelatinase by human macrophages

Macrophages are present in inflammatory tissue sites where abnormal degradation of the extracellular matrix takes place. To evaluate the potential of macrophages to participate in such matrix destruction, we studied the effects of three cytokines present in inflammatory tissue sites, TNF-alpha, IL-1beta, and IFN-gamma, on the production of three matrix-degrading metalloproteinases, interstitial collagenase, stromelysin, and 92-kDa gelatinase, as well as their natural inhibitor, TIMP-1 (tissue inhibitor of metalloproteinases number 1), by human monocyte-derived macrophages differentiated in vitro. Spontaneous production of interstitial collagenase and stromelysin by these cells was minimal, and was not influenced by the cytokines. In contrast, the cells secreted substantial basal amounts of 92-kDa gelatinase, the secretion of which was stimulated (2- to 15-fold; on average 5-fold) by both TNF-alpha and IL-1beta, while the production of TIMP-1 was unaffected. IFN-gamma suppressed the production of the 92-kDa gelatinase induced by TNF-alpha- and IL-1beta. TNF-alpha and IL-1beta regulated the expression of 92-kDa gelatinase by monocyte-derived macrophages at the pretranslational level. The results show that expression of 92-kDa gelatinase, but not its natural inhibitor TIMP-1, by human tissue-type macrophages is selectively up-regulated by proinflammatory cytokines; which suggests that these cells, when actually present in an inflammatory environment, will actively participate in the destruction of the extracellular matrix.     

Expression of 72-kDa gelatinase (matrix metalloproteinase-2) in the developing mouse craniofacial complex

Tissue remodelling is an important feature during embryogenesis. Although the matrix metalloproteinases are believed to participate in these processes, the relation between matrix metalloproteinases and tissue remodelling during craniofacial morphogenesis remains unclear. The purpose of the study was to look for the presence of enzymes involved in extracellular matrix degradation during craniofacial morphogenesis. Protein expression of the matrix metalloproteinase, 72-kDa gelatinase (matrix metalloproteinase-2, gelatinase A, 72-kDa type IV collagenase) was studied by gelatine zymography and by indirect immunofluorescence with conventional and confocal microscopy. In the anterior region of the developing mouse face, 72-kDa gelatinase was labelled mainly in the tips and peripheral regions of the nasal and facial prominences. Upon contact and fusion of the prominences, the staining was intensely localized to the zone of the fusion and the tips and peripheral regions of the nasal prominences and the maxilla. The labelling of 72-kDa gelatinase was also present in the peripheral regions of the mandible, second branchial arch, and the face around the developing eye. However, during lens vesicle formation, the staining of 72-kDa gelatinase was absent in the invaginated lens ectoderm. After the lens had completely detached from the surface ectoderm, the staining was resumed in the corneal epithelium and mesenchyme. Gelatine zymography was used to confirm the presence of active and latent 72-kDa gelatinase in the developing mouse craniofacial complex. Collectively, these data indicate that 72-kDa gelatinase may play a significant part in localized tissue remodelling during craniofacial morphogenesis and the aberrant expression or function of the enzyme could be involved in causing facial abnormalities.     

Increased gelatinase A (MMP-2) and gelatinase B (MMP-9) activities in human brain after focal ischemia

Matrix metalloproteinases (MMPs) are involved in remodelling extracellular matrix. Gelatinase B (MMP-9) is an inducible 92 kDa MMP expressed by neutrophils, microglia, and endothelial cells. Gelatinase A (MMP-2) is a 72 kDa MMP, constitutively expressed in brain. Elevated MMP activity has been linked to various pathologic conditions, and the therapeutic benefit of MMP inhibitors is under study in a few experimental models. Using gelatin zymography, we have compared activities of these MMPs in infarcted and matched non-infarcted cerebral tissue from eight subjects dying at intervals of less than 2 h to several years after a stroke. Gelatinase B activity was markedly elevated in the infarcted tissue at two days post-infarction, and remained elevated in cases dying months after the event. Increases in gelatinase A activity were subtle at 2-5 days; they were marked and significant in cases dying at 4 months and later. The findings indicate distinct temporal profiles of post-ischemic gelatinase activity in human brain, with earlier but equally persistent elevation in gelatinase B when compared to gelatinase A.     

Matrix metalloproteinases and metalloproteinase inhibitors in choroidal neovascular membranes

PURPOSE: Matrix metalloproteinases (MMP) are a family of extracellular matrix degrading enzymes associated with the development of neovascularization. To investigate the possible role of these enzymes in choroidal neovascularization, the mRNA expression of MMPs and tissue inhibitors of metalloproteinases (TIMPs) were analyzed in subfoveal fibrovascular membranes from patients with age-related macular degeneration (AMD). METHODS: Surgically removed subfoveal fibrovascular membranes from five eyes were analyzed for the expression of MMP and TIMP mRNA. In situ hybridization anti-sense and sense riboprobes were generated using DNA complementary to human collagenase (MMP-1), 72 kDa gelatinase (MMP-2), stromelysin (MMP-3), 92-kDa gelatinase (MMP-9), TIMP-1, TIMP-2, and TIMP-3. Vascular endothelial cells were detected using immunostaining for von Willebrand factor. RESULTS: MMP-2 and MMP-9 mRNA were detected in all specimens. Most of the membranes also expressed TIMP-1 and TIMP-3 mRNA, and two of the membranes expressed TIMP-2 mRNA. MMP-2, TIMP-1, and TIMP-2 mRNA had a similar overall distribution that was relatively uniform within the vascularized membrane stroma. MMP-2 expression appeared to be localized mainly to the vascular endothelial cells, whereas TIMP-1 and TIMP-3 were detected in other cell types such as fibroblastlike cells. MMP-9 expression was distinctly expressed by cells at the margins of the membranes and often in proximity to a thickened Bruch's membrane-like layer under the retinal pigment epithelial cells. TIMP-3 mRNA was strongly expressed within the retinal pigment epithelial cell layer and also in the stroma of one membrane. None of the membranes showed detectable MMP-1 or MMP-3 expression. CONCLUSIONS: The results support a role for MMPs in the development of choroidal neovascularization in AMD. The localization of MMP-2 and MMP-9 to the areas of new vessel formation and to the enveloping Bruch's-like membrane, respectively, suggests that MMP-2 and MMP-9 may be cooperatively involved in the progressive growth of choroidal neovascular membranes in AMD.     

Expression of matrix metalloproteinases and tissue inhibitors of metalloproteinases in HTLV-I-associated myelopathy

Matrix metalloproteinases (MMPs) have been reported to be involved in inflammatory disorders of the central nervous system (CNS). However, little is known about the role of MMPs in the pathogenesis of HTLV-I-associated myelopathy (HAM)/Tropical spastic paraparesis (TSP). To address this issue, we examined the tissue expression and localization of MMPs and their inhibitors, tissue inhibitors of metalloproteinases (TIMPs) in the spinal cord lesions of HAM/TSP using immunohistochemistry. In addition, the blood and cerebrospinal fluid (CSF) levels of MMPs and TIMPs of the patients with HAM/TSP were determined using sandwich enzyme immunoassays (SIA) and gelatin zymography. Immunohistochemical studies revealed that collagen IV and decorin immunoreactivity on the basement membrane of CNS parenchymal vessels was partially disrupted where inflammatory mononuclear cells infiltrated in active-chronic lesions of HAM/TSP. In these lesions, MMP-2 (gelatinase A) was immunostained mainly on the surface of foamy macrophages and lymphocytes, whereas MMP-9 (gelatinase B) expression was positive in the intravascular and perivascular mononuclear cells but not on foamy macrophages. In contrast, inactive chronic lesions of the spinal cords of the HAM/TSP contained fewer MMP-2-positive or MMP-9-positive mononuclear cells than active-chronic lesions. Many parenchymal vessels had thickened vascular walls which showed increased immunoreactivity to decorin. SIA revealed that production levels of MMP-2 and MMP-9 in both blood and CSF were higher in the patients with HAM/TSP than those in non-inflammatory other neurological disease controls (ONDs). Using zymography, proMMP-9 was detected more frequently in the CSF of patients with HAM/TSP than those in ONDs. Taken together, our data indicate that MMP-2 and MMP-9 may play an important role in the blood-brain barrier breakdown and tissue remodeling in the CNS of HAM/TSP.     

Increased production of gelatinase B (matrix metalloproteinase-9) and interleukin-6 by activated rat microglia in culture

Activated macrophages produce several matrix metalloproteinases (MMPs), a family of extracellular matrix (ECM)-degrading enzymes, during wound healing and in other inflammatory states. In response to brain injury, brain microglia become "activated," in a way similar to peripheral tissue macrophages, a process which includes differentiation and probably invasion and proliferation. Little is known about the ECM-degrading MMPs that are secreted by microglia upon activation. Thus, it was of interest to determine whether activated microglia secrete MMPs. Conditioned media samples obtained from cultured microglia that were stimulated with various activating agents were subjected to gelatin-substrate zymography. Microglia constitutively express low levels of a 94-kDa gelatinase (GLase) activity. Treatment with LPS, zymosan, and fixed Staphylococcus aureus for 24 hr stimulated the activity of the 94-kDa GLase, 4-20-fold, in a dose-dependent manner. Addition of INF gamma inhibited the LPS-stimulated activity of MMP-9. LPS, zymosan, and fixed Staphylococcus aureus also stimulated the secretion of IL-6 from microglia in a dose-dependent manner. The 94-kDa GLase activity was Ca++ dependent, it was inhibited by 1,10-phenanthroline, and it was activated by organomercurial compounds. When immunoblots were performed using specific antisera against the 94-kDa gelatinase B (MMP-9) with untreated and LPS-stimulated conditioned medium samples, a 94-kDa immunopositive band was observed. Thus, it appears that the 94-kDa GLase is gelatinase B (MMP-9). These results indicate that activators of peripheral macrophages are potent secretagogues for the MMPs in cultured microglia. The ability of activated microglia to secrete MMPs suggests that these enzymes may play an important function in the brain parenchyma during inflammatory states.     

Gene expression of MMPs and TIMPs in the process of hepatic fibrosis

The matrix metalloproteinases (MMPs) gene family includes MMP-1 (interstitial collagenase), MMP-2 (72 kD type IV collagenase/gelatinase), MMP-3 (stromelysin/transin), MMP-7 (putative MMP; pump-1), MMP-8 (granulocyte collagenase) and MMP-9 (92 kD type IV collagenase/gelatinase). This gene family has the common characteristics in the gene structure as follows: All of MMPs have the active site metal ion-binding domain. All six enzymes are activated with the concomitant removal of N-terminal segment of the latent enzyme. The removed segment contains an unpaired cystein residue within the conserved amino acid sequence PRCGVPDV, located immediately adjacent to the proenzyme cleavage site. The authors showed the gene expression of MMP-1 in the process of hepatic fibrosis. The remarkable expression was noted on fibroblasts and macrophages within the newly-formed fibrous bands with lots of infiltrated lymphocytes. Liver cirrhosis did not showed the positive dots of MMP-1 mRNA. On the other hands, the expression of TIMP reported by Takahara et al., revealed the high level of expression in the advanced fibrosis.     

Plasma membrane-bound tissue inhibitor of metalloproteinases (TIMP)-2 specifically inhibits matrix metalloproteinase 2 (gelatinase A) activated on the cell surface

The cell-surface activation of pro-matrix metalloproteinase 2 (pro-MMP-2) is considered to be critical for cell migration and invasion. Treatment of human uterine cervical fibroblasts with concanavalin A activates pro-MMP-2 on the cell surface by converting it to the 65-kDa form with a minor form of 45 kDa. However, the 65-kDa MMP-2 was inactivated by tissue inhibitor of metalloproteinases (TIMP)-2 that was bound to the plasma membrane upon concanavalin A treatment. TIMP-2 binds to the plasma membrane through its N-terminal domain by two different modes of interaction as follows: one is sensitive to a hydroxamate (HXM) inhibitor of MMPs and the other is HXM-insensitive. TIMP-2 bound to the membrane in a HXM-insensitive manner, comprising about 40-50% of TIMP-2 on the membrane, is the inhibitor of the cell surface-activated MMP-2. It, however, does not inhibit MMP-3, MMP-9, and the 45-kDa MMP-2 lacking the C-terminal domain. The inhibition of the 65-kDa MMP-2 by TIMP-2 is initiated by the interaction of their C-terminal domains. Subsequently, the MMP-2.TIMP-2 complex is released from the membrane, and the activity of MMP-2 is blocked by TIMP-2. In the presence of collagen types I, II, III, V, or gelatin, the rate of inhibition of the 65-kDa MMP-2 by the membrane-bound TIMP-2 decreased considerably. These results suggest that the pericellular activity of MMP-2 is tightly regulated by membrane-bound TIMP-2 and surrounding extracellular matrix components.     

Dog mast cell alpha-chymase activates progelatinase B by cleaving the Phe88-Gln89 and Phe91-Glu92 bonds of the catalytic domain

In prior work we showed that a metallogelatinase is secreted from dog mastocytoma cells and directly activated by exocytosed mast cell alpha-chymase. The current work identifies the protease as a canine homologue of progelatinase B (92-kDa gelatinase, MMP-9), determines the sites cleaved by alpha-chymase, and explores the regulation of gelatinase expression in mastocytoma cells. To obtain a cDNA encoding the complete sequence of mastocytoma gelatinase B, a 2. 3-kilobase clone encoding progelatinase was isolated from a BR mastocytoma library. The sequenced cDNA predicts a 704-amino acid protein 80% identical to human progelatinase B. Regions thought to be critical for active site latency, such as the Cys-containing propeptide sequence, PRCGVPD, and the catalytic domain sequence, HEFGHALGLDHSS, are entirely conserved. Cleavage of progelatinase B by purified dog alpha-chymase yielded an approximately 84-kDa product that contained two NH2-terminal amino acid sequences, QTFEGDLKXH and EGDLKXHHND, which correspond to residues 89-98 and 92-101 of the cDNA predicted sequence, respectively. Thus, alpha-chymase cleaves the catalytic domain of gelatinase B at the Phe88-Gln89 and Phe91-Glu92 bonds. Like BR cells, the C2 line of dog mastocytoma cells constitutively secrete progelatinase B which is activated by alpha-chymase. By contrast, non-chymase-producing C1 cells secrete a gelatinase B (which remains in its proform) only in response to 12-O-tetradecanoylphorbol-13-acetate. Whereas 12-O-tetradecanoylphorbol-13-acetate stimulation of BR cells produced a approximately 15-fold increase in gelatinase B mRNA expression, dexamethasone down-regulated its expression by approximately 5-fold. Thus, extracellular stimuli may regulate the amount of mast cell progelatinase B expressed by mast cells. These data further support a role for mast cell alpha-chymase in tissue remodeling involving gelatinase B-mediated degradation of matrix proteins.     

Autocrine regulation of matrix metalloproteinase-9 gene expression and secretion by tumor necrosis factor-alpha (TNF-alpha) in NB4 leukemic cells: specific involvement of TNF receptor type 1

Matrix metalloproteinases have been reported to be involved in tumor cell invasion and metastasis. Dissemination of malignant cells in acute myeloid leukemia (AML) may be mediated by similar mechanisms. Here, we report, that the t(15/17)+ acute promyelocytic leukemia (APL) cell line NB4 constitutively expresses and releases the proenzyme form of matrix metalloproteinase-9 (MMP-9, 92 kDa type IV collagenase/gelatinase, gelatinase B), as well as tissue inhibitor of metalloproteinases-1 (TIMP-1). Both proteins were identified by N-terminal amino acid sequence analysis after purification using gelatin Sepharose affinity chromatography. Whereas 12-O-tetradecanoylphorbol-13 acetate (TPA) increased both MMP-9 and TIMP-1 mRNA levels, tumor necrosis factor-alpha (TNF-alpha) stimulated only MMP-9 gene expression in a dose- and time-dependent manner. Neutralizing monoclonal antibodies (MoABs) to TNF-alpha (anti-TNF-alpha) decreased the constitutive and TPA-dependent expression of MMP-9 but did not influence TIMP-1 expression, either in unstimulated or in TPA-treated NB4 cells. FACS analyses showed that NB4 cells express both TNF receptor 1 (TNF-R1) and TNF-R2 to a similar extent. Blocking MoABs against TNF-R 1 (anti-TNF-R1) decreased the constitutive expression of MMP-9, whereas anti-TNF-R2 had almost no effect. Our results show, that in NB4 cells the expression of MMP-9 but not of TIMP-1 is maintained by autocrine stimulation with TNF-alpha. Thus, leukemic cells may be enabled to leave the bone marrow and infiltrate peripheral tissues by a dysfunction in the regulation of the MMP-9:TIMP-1 equilibrium, possibly triggered through autostimulation by TNF-alpha.     

Bacterial phospholipase C upregulates matrix metalloproteinase expression by cultured epithelial cells

Phospholipase C (PLC) is a putative virulence factor of several pathogenic bacteria. We studied if exogenous PLC would perturb epithelial behavior in infected tissues. Gelatin and casein zymography of cell culture medium indicated that the broad-spectrum PLC of Bacillus cereus induced matrix metalloproteinase (MMP) production in epithelial cells of human skin (NHEK), human gingiva (HGE), and porcine periodontal ligament (PLE). In all three cell types, the strongest increase (ninefold) at 0.1 U/ml was seen in the MMP-9 (92-kDa gelatinase) activity, and the effect was dose dependent in the range of 0.1 to 1.0 U/ml. A relatively weaker increase (twofold) in MMP-2 (72-kDa gelatinase) was also observed in each cell type. PLC induction of MMP-3 (48-kDa stromelysin) was also seen in NHEK and HGE on gelatin and more sensitively for PLE by casein zymography (fivefold). Total gelatinolytic activity as measured by degradation of 14C-labeled denatured type I collagen increased by about 18-fold (NHEK), 12-fold (HGE), and 14-fold (PLE). Northern analysis showed a clear increase in the MMP-9, and a minor increase in MMP-3 mRNA levels but no significant increase in MMP-2 mRNA levels. Further studies with PLE revealed that MMP-9 induction by PLC progressively increased with the length of cell culture time in the absence of serum. PLC induction of MMPs was polar, with MMP-9 and MMP-3 secreted primarily in the apical direction and MMP-2 secreted mainly in the basal direction. The PLC effect was blocked by neomycin, an inhibitor of the phosphoinositol signal pathway. No significant effects were observed in MMP expression with the calcium ionophore A23187 or phospholipase A2. Morphologically, PLC treatment resulted in reduced contacts between the cultured cells and loss of the cell surface microvilli. These results suggest that PLC secreted by bacterial pathogens may disrupt epithelium of infected tissue and increase the subepithelial tissue destruction through induction of MMPs.     

Cytogenetic analysis of sister chromosome sets in the second polar body and in pronuclei of unicellular mouse embryos. I. Frequency and origin of aneuploidy in embryos heterozygous for the reciprocal chromosome translocation T[14;15]6Ca]

Matrix metalloproteinases have been implicated to play a vital role in glioma invasion as they degrade extracellular matrix to facilitate the subsequent migration of tumor cells into the surrounding brain tissue. The cytokine Interleukin-10 (IL-10) was detected recently in glial tumors in vivo. Expression of specific IL-10 mRNA as well as blood serum levels of IL-10 in glioma patients increased with malignancy suggesting a functional role of IL-10 in glioma progression. Moreover, glioma cell migration in vitro was enhanced in the presence of IL-10. We therefore investigated the expression of the matrix metalloproteinases (MMPs) stromelysin-1 (MMP-3), 72-kDa collagenase (MMP-2), 92-kDa collagenase (MMP-9), matrilysin (MMP-7) and the human macrophage metalloelastase (MMP-12). In addition, a possible relation between exposure of glioma cells to IL-10 and invasiveness of these cells due to MMP expression was analyzed. Experiments with Matrigel coated Boyden chambers revealed a pronounced dose dependent effect of IL-10 on glioma invasiveness. The synthetic MMP-inhibitor Marimastat markedly reduced cell invasion in the Boyden chambers confirming the significance of MMPs in the process of invasion. Subsequently, the expression level of MMPs and the serine protease uPA was investigated in 7 glioma cell lines (U373, GaMG, U251, GHE, SNB19, U138 and D54) by RT-PCR. In all but one cell line no enhancement of MMP expression by IL-10 was detected. Matrilysin in U373 cells was the only protease found to be upregulated in the presence of IL-10 dependent on cell density. The present data suggest that IL-10 related effects on the invasive properties of the cell lines are not directly mediated by an upregulation of matrix metalloproteinase expression.     

Effect of matrix metalloproteinases activity on outflow in perfused human organ culture

PURPOSE: To test the hypothesis that extracellular matrix turnover, mediated by the matrix metalloproteinases, modulates aqueous humor outflow facility in a human outflow model. METHODS: Matrix metalloproteinase activity was manipulated and outflow facility evaluated using perfused human anterior segment organ culture. Purified matrix metalloproteinases, tissue inhibitors of metalloproteinases (TIMPs), and several families of synthetic inhibitors of matrix metalloproteinases were added to the perfusion medium. Matrix metalloproteinase expression was increased by adding recombinant interleukin (IL)-1alpha. Kinetic inhibition analysis was conducted for stromelysin, gelatinase A, and gelatinase B with the various inhibitors. Live-dead staining was used to evaluate culture viability. RESULTS: Increasing metalloproteinase activity, by adding purified metalloproteinases or by inducing their expression by IL-1alpha treatment, increased outflow facility. Inhibition of endogenous trabecular metalloproteinase activity using TIMP or several families of synthetic metalloproteinase inhibitors reduced outflow rates. The elevation and the reduction of outflow rates were reversible, with changes requiring 1 to 3 days. Kinetic enzyme inhibition analysis produced 50% inhibitory concentration values for these inhibitors that were compatible with the concentration ranges for outflow inhibition. CONCLUSIONS. The ability of several specific matrix metalloproteinase inhibitors to reduce outflow facility implies that endogenous extracellular matrix turnover by these enzymes was required for the maintenance of trabecular outflow resistance, at least in this human culture model. These observations provide support for the hypothesis that controlled extracellular matrix turnover is important in the regulation of aqueous humor outflow facility.     

Increased expression of matrix metalloproteinases in vivo in scleritis tissue and in vitro in cultured human scleral fibroblasts

Scleritis is a sight-threatening inflammatory disorder of the eye characterized by the degradation of scleral matrix. Matrix metalloproteinases (MMPs) are ubiquitous proteolytic enzymes important in physiological and pathological processes, the activity of which is stringently controlled by the action of a family of natural antagonists, the tissue inhibitors of matrix metalloproteinases (TIMPs). We hypothesized that enhanced expression of MMPs, without the negative regulatory influence of TIMPs, may be a key feature of tissue destruction in inflammatory eye diseases, such as scleritis. The aim of this study was to localize and characterize cells expressing MMPs and TIMPs in sclera affected by necrotizing scleritis and, in a parallel study, to establish whether cytokines modulate MMP expression in cultured human scleral fibroblasts. In situ hybridization and immunohistochemical analyses indicated that resident scleral fibroblasts as well as inflammatory cells such as macrophages and T lymphocytes express stromelysin, gelatinase B, and TIMP-1 in necrotizing scleritis tissue. In addition, cytoplasmic immunoreactivity for tumor necrosis factor-alpha, an inducer of MMPs, was detected in infiltrating inflammatory cells. Cultured scleral fibroblasts stimulated with the combination of interleukin-1 alpha plus tumor necrosis factor-alpha increased TIMP-1 mRNA twofold above constitutive levels. By contrast, these cytokines induced a sevenfold increase in the steady-state levels of stromelysin mRNA. Using Western blotting, stromelysin and TIMP-1 protein production paralleled mRNA induction in cytokine-stimulated human scleral fibroblasts. Culture supernatants harvested from cytokine-stimulated human scleral fibroblasts were subjected to sodium dodecyl sulfate polyacrylamide gel electrophoresis gelatin substrate zymography. Our results revealed a prominent 92-kd gelatinolytic band corresponding to gelatinase B, which was inducible with interleukin-1 alpha. These data provide evidence for our hypothesis, that an imbalance between enzyme/inhibitor ratios may be the underlying mechanism of the tissue destruction characteristic of scleritis. Our results demonstrate the potential involvement of MMPs and their modulation by cytokines produced by infiltrating inflammatory cells in destructive ocular inflammation.     

Production and localization of 92-kilodalton gelatinase in abdominal aortic aneurysms. An elastolytic metalloproteinase expressed by aneurysm-infiltrating macrophages

Abdominal aortic aneurysms (AAA) are characterized by disruption and degradation of the elastic media, yet the elastolytic proteinases involved and their cellular sources are undefined. We examined if 92-kD gelatinase, an elastolytic matrix metalloproteinase, participates in the pathobiology of AAA. Gelatin zymography of conditioned medium from normal, atheroocclusive disease (AOD), or AAA tissues in organ culture showed that all tissues produced 72-kD gelatinase. AOD and AAA cultures also secreted 92-kD gelatinase, but significantly more enzyme was released from AAA tissues. ELISA confirmed that AAA tissues released approximately 2-fold more 92-kD gelatinase than AOD tissue and approximately 10-fold more than normal aorta. Phorbol ester induced a 5.3-fold increase in 92-kD gelatinase secretion by normal aorta and AOD and an 11.5-fold increase by AAA. By immunohistochemistry, 92-kD gelatinase was not detected in normal aorta and was only occasionally seen within the neointimal lesions of AOD tissue. In all AAA specimens, however, 92-kD gelatinase was readily localized to numerous macrophages in the media and at the adventitial-medial junction. The expression of 92-kD gelatinase mRNA by aneurysm-infiltrating macrophages was confirmed by in situ hybridization. These results demonstrate that diseased aortic tissues secrete greater amounts of gelatinolytic activity than normal aorta primarily due to increased production of 92-kD gelatinase. In addition, the localization of 92-kD gelatinase to macrophages in the damaged wall of aneurysmal aortas suggests that chronic release of this elastolytic metalloproteinase contributes to extracellular matrix degradation in AAA.     

Effects of cetirizine on the delayed K+ currents in cardiac cells: comparison with terfenadine

On direct cell-cell contact, stimulated T lymphocytes potently trigger the production of pro-inflammatory factors such as interleukin-1beta (IL-1beta) and matrix metalloproteinases (MMP-1 and MMP-9), as well as anti-inflammatory factors such as IL-1 receptor antagonist (IL-1Ra) and the tissue inhibitor of metalloproteinases (TIMP-1) in peripheral blood monocytes and the monocytic cell line THP-1. Such mechanisms might play an important part in many inflammatory diseases where tissue destruction occurs. To assess whether anti-inflammatory agents such as dexamethasone (DEX) and leflunomide (LF) would affect contact-activation of monocytic cells, T lymphocytes were stimulated by PMA and PHA in the presence or absence of increasing concentrations of drug. LF and DEX (10- 4 M) inhibited the ability of stimulated T lymphocytes to activate monocytic cells by 66-97% and 43-70%, respectively, depending on the readout product. Upon contact with T lymphocytes stimulated in the presence of 10- 5 M LF, the molar ratio of IL-1Ra/IL-1beta and TIMP-1/MMP-1 produced by THP-1 cells was enhanced 3.6- and 1.9-fold, respectively, whereas it was enhanced only 1.3- and 1.4-fold upon contact with T lymphocytes stimulated in the presence of 10- 4 M DEX. Therefore, LF tends to favor the inhibition of pro-inflammatory and matrix-destructive factors over that of anti-inflammatory factors and metalloproteinase inhibitors, thus interfering with both inflammation and tissue destruction. These experiments indicate that LF and DEX have the potential to affect the capacity of stimulated T lymphocytes to activate, on direct cell-cell contact, monocytic cells. Furthermore, flow cytometric analysis revealed that surface molecules of T lymphocytes that were partially involved in contact-signaling of monocytes (i.e., CD69 and CD11) were not modulated by either LF or DEX, suggesting that factors which remain to be identified were mainly involved in the activation of monocytes on direct cell-cell contact.     

Membrane components of Treponema denticola trigger proteinase release from human polymorphonuclear leukocytes

Tissue destruction during periodontitis is believed to be primarily brought about by leukocyte proteinases. We postulate that oral spirochetes cause discharge of polymorphonuclear leukocyte (PMN) lysosomal enzymes. Effects of Treponema denticola 53-kDa outer membrane protein, lipopolysaccharide (LPS), and peptidoglycan on degranulation of matrix metalloproteinases (MMP)-8 (collagenase) and -9 (gelatinase), cathepsin G, and elastase by human peripheral blood PMNs were studied by specific enzyme assays and Western blot analysis. T. denticola 53-kDa kDa outer membrane protein was found to be a particularly efficient inducer of MMP-8 release. The induction was comparable with that of phorbol myristate acetate, a known inducer of PMN specific granule discharge. All of the treponemal substances, most notably the 53-kDa protein and LPS, induced release of MMP-9, a component of C-type granules. Both collagenase and gelatinase released from PMNs were mostly in active forms. Release of cathepsin G and elastase was also observed with the 53-kDa protein treatment. The other T. denticola substances did not induce release of these serine proteinases. Lactate dehydrogenase was not released from PMNs by the treatments, indicating that the degranulation was specific and not caused by toxic effects of the substances. This was confirmed by transmission electron microscopy of PMNs treated with the 53-kDa protein that showed rapid vacuole formation and cell shape changes but no disintegration of the cells. Thus, T. denticola may participate in the PMN-dependent extracellular matrix degradation during the course of periodontal inflammation by triggering the secretion and activation of matrix metalloproteinases.