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

Mast cell chymase contributes to the antibody response and the severity of autoimmune arthritis

Mast cells are implicated in rheumatoid arthritis, but the mechanism by which they contribute to disease progression is not clarified. Here we investigated whether mouse mast cell protease-4 (mMCP-4), a chymase present in the mast cell secretory granule, contributes to experimental arthritis. Two models of arthritis were investigated in mMCP-4(+/+) and mMCP-4(-/-) DBA/1 mice: collagen-induced arthritis (CIA) was induced by immunization with collagen II (CII) in Freund's complete adjuvant, and a passive model of arthritis was induced by administration of anti-CII antibodies. The clinical scores were significantly reduced in the mMCP-4(-/-) animals as compared to mMCP-4(+/+) controls in both arthritis models. In CIA, the number of affected paws was lower in the CII-immunized mMCP-4(-/-) mice, with less cartilage destruction, pannus formation, and mononuclear cell and mast cell influx in the mMCP-4(-/-) joints. Interestingly, the lower clinical scores in the CII-immunized mMCP-4(-/-) mice coincided with lower serum levels of immunoglobulin G anti-CII antibodies. Our findings identify a pathogenic role of mMCP-4 in autoimmune arthritis.

Effects of chymase inhibitor on angiotensin II-induced abdominal aortic aneurysm development in apolipoprotein E-deficient mice

OBJECTIVE

Chymase may play an important role in abdominal aortic aneurysm (AAA) development through matrix metalloproteinase (MMP)-9 activation. The purpose of this study was to determine whether chymase is involved in angiotensin (Ang) II-induced AAA development in apolipoprotein E (apoE)-deficient mice.

METHODS AND RESULTS

In this study, Ang II (1000 ng/kg/min; vehicle group) or saline (saline group) was administered to 16-week-old, male, apoE-deficient mice for 4 weeks. To examine the effects of chymase inhibition on AAA development, oral NK3201 (30 mg/kg/day) was given for the same period as the Ang II infusion. AAAs developed at the suprarenal region of the abdominal aorta in the Ang II-treated vehicle group, but they were not observed in the saline group. On the other hand, the severity and luminal area of the AAAs in the Ang II-treated vehicle group were significantly suppressed by NK3201 treatment. MMP-9 activity was significantly lower in the Ang II-treated+NK3201-treated group than in the Ang II-treated vehicle group. Furthermore, there were significantly fewer monocyte/macrophage cells in the Ang II-treated+NK3201-treated group than in the Ang II-treated vehicle group.

CONCLUSIONS

Chymase is involved in Ang II-induced AAA development in apoE-deficient mice.

Antitumor activities of synthetic and natural stilbenes through antiangiogenic action

We reported that the antitumor and antimetastatic actions of resveratrol might be due to the inhibition of tumor-induced angiogenesis. To search for anticancer agents with stronger activity than resveratrol, we examined the antiangiogenic effects of 21 synthetic and/or natural stilbenes. Among these 21 stilbenes, 2,3-, 3,4-, and 4,4'-dihydroxystilbene inhibited the pro-matrix metalloproteinase (pro-MMP)-9 production in colon 26 cells at 5-25 microM, vascular endothelial growth factor (VEGF)-induced human umbilical vein endothelial cell (HUVEC) migration at 10 and 25 microM, and VEGF-induced angiogenesis at 5-50 microM. Resvertarol inhibited the pro-MMP-9 production and VEGF-induced angiogenesis at 25 or 50 microM. Thus, the inhibition of pro-MMP-9 production in colon 26 cells and VEGF-induced angiogenesis by three dihydroxystilbenes were greater than those of resveratrol. The three dihydroxystilbenes (8 mg/kg, intraperitoneal injection) inhibited the tumor-induced neovascularization in colon 26-packed chamber-bearing mice and the tumor growth in colon 26-bearing mice. Furthermore, the three dihydroxystilbenes inhibited VEGF-induced VEGFR-2 phosphorylation. On the other hand, the three dihydroxystilbenes had no effect on VEGFR-1 and-2 expression, and VEGF-induced VEGFR-1 phosphorylation in HUVECs. These findings suggest that the inhibition of tumor-induced neovascularization by these three dihydroxystilbenes may be due to the inhibition of VEGF-induced endothelial cell migration and VEGF-induced angiogenesis through the inhibition of VEGF-induced VEGFR-2 phosphorylation in endothelial cells and pro-MMP-9 expression in colon 26 cells.

Inhibitory profiles of captopril on matrix metalloproteinase-9 activity

To investigate the inhibitory profiles of angiotensin-converting enzyme (ACE) inhibitors on matrix metalloproteinase-9 (MMP-9) activity, the inhibitory activity and molecular interaction of captopril on human MMP-9 were studied. Plasma MMP-9 and ACE activities in samples from patient with acute myocardial infarction were similarly inhibited by captopril. Molecular models showed that captopril directly bound to the MMP-9 active center. Compared with the other ACE inhibitors, the compact structure of captopril seemed to make the inhibitory profiles on the MMP-9 active site.

Role of chymase-dependent matrix metalloproteinase-9 activation in mice with dextran sodium sulfate-induced colitis

Matrix metalloproteinase (MMP)-9 plays an important role in the pathogenesis of colitis. Recent studies have demonstrated that chymase is involved in the conversion of promatrix metalloproteinase (proMMP)-9 to MMP-9. However, whether chymase contributes to the activation of proMMP-9 in colitis has remained unclear. In this study, we administered 5% dextran sodium sulfate (DSS) solution to mice for 7 days. At 7 days after starting administration, both chymase activity and MMP-9 activity were significantly increased. In extract from colitis in DSS-treated mice, MMP-9 activity was significantly increased after 8 h of incubation, but increased activity was almost completely suppressed in the presence of a chymase inhibitor, 2-(5-formylamino-6-oxo-2-phenyl-1,6-dihydropyrimidine-1-yl)-N-[{3,4-dioxo-1-phenyl-7-(2-pyridyloxy)}-2-heptyl] acetamide (NK3201). At 7 days after starting administration, intestinal length was significantly shorter in DSS-treated mice than in normal mice, but these changes were significantly prevented by NK3201 (10 mg/kg per day i.p.). Disease activity index and histological damage score were also significantly reduced by NK3201. The filtrated neutrophil number was significantly decreased by NK3201. Furthermore, NK3201 significantly attenuated not only chymase activity but also MMP-9 activity in DSS-treated mice. These findings suggest that chymase plays an important role in the development of colitis via MMP-9 activation.

Significance of matrix metalloproteinase-9 in cardiac dysfunction during the very acute phase after myocardial infarction in hamsters

Matrix metalloproteinase-9 activity is dramatically increased during the acute phase after myocardial infarction. However, the relationship between matrix metalloproteinase-9 activity and cardiac dysfunction is unclear. In 1-day post-myocardial infarction hamsters, matrix metalloproteinase-9 activity was significantly increased, while matrix metalloproteinase-2 activity was not increased. A selective matrix metalloproteinase inhibitor, [2S,4S]-N-Hydroxy-5-ethoxymethyloxy-2-methyl-4-[4-phenoxybenzoyl] aminopentanamide (ONO-4817), significantly suppressed matrix metalloproteinase-9 activity 1 day after myocardial infarction. ONO-4817 also significantly prevented the development of cardiac dysfunction and left-ventricular dilatation. Matrix metalloproteinase-9 might play a crucial role in cardiac dysfunction and left-ventricular dilatation during the very acute phase after myocardial infarction.

Control of matrix metalloproteinase catalytic activity

As their name implies, MMPs were first described as proteases that degrade extracellular matrix proteins, such as collagens, elastin, proteoglycans, and laminins. However, studies of MMP function in vivo have revealed that these proteinases act on a variety of extracellular protein substrates, often to activate latent forms of effector proteins, such as antimicrobial peptides and cytokines, or to alter protein function, such as shedding of cell-surface proteins. Because their substrates are diverse, MMPs are involved in variety of homeostatic functions, such as bone remodeling, wound healing, and several aspects of immunity. However, MMPs are also involved in a number of pathological processes, such as tumor progression, fibrosis, chronic inflammation, tissue destruction, and more. A key step in regulating MMP proteolysis is the conversion of the zymogen into an active proteinase. Several proMMPs are activated in the secretion pathway by furin proprotein convertases, but for most the activation mechanisms are largely not known. In this review, we discuss both authentic and potential mechanisms of proMMP activation.

Gelatinase B/MMP-9 as an inflammatory marker enzyme in mouse zymosan peritonitis: comparison of phase-specific and cell-specific production by mast cells, macrophages and neutrophils

Neutrophil infiltration during zymosan peritonitis depends on matrix metalloproteinase-9 (MMP-9) activity as it is impaired both in MMP-9(-/-) and gelatinase inhibitor-treated animals. The producer cells of MMP-9 and their relative contribution are not known. The aim of this study was to identify and compare the cellular sources, timing and intensity of MMP-9 induction by zymosan in the murine peritoneal cavity. We detected MMP-9 mRNA in unstimulated peritoneal leukocytes and its levels increased after zymosan administration. To detect MMP-9 by flow cytometry, we selected and compared two specific monoclonal antibodies. We show that MMP-9 protein was absent in control peritoneal macrophages, whereas already at 30min of peritonitis almost all macrophages were producing the enzyme. Conversely, MMP-9 was constitutively present in unstimulated mast cells. Macrophages turned out to be prevalent MMP-9 producers in the early phase of peritonitis. During later stages macrophages kept the high expression of MMP-9 for at least 6h of inflammation. In contrast, the early phase expression of MMP-9 by neutrophils was limited albeit the highest percentage of MMP-9(+) neutrophils was observed at 2h but absolute numbers of the MMP-9 carrying neutrophils were low at that time. In contrast, during the late phase of peritonitis neutrophils became major producers of MMP-9 as they numerously infiltrated peritoneum. In conclusion, the study reports detection of MMP-9 at the single-cell level during peritonitis, demonstrates unexpectedly fast MMP-9 expression in macrophages and reveals quantitatively phase-specific contribution of mast cells, macrophages and neutrophils.

Molecular mechanism of imidapril for cardiovascular protection via inhibition of MMP-9

To investigate the inhibitory specificity of angiotensin converting enzyme (ACE) inhibitors to matrix metalloproteinase (MMP)-9, we predicted molecular interactions between an ACE inhibitor imidapril and MMP-9 active site based on recent X-ray structural analyses. Two binding modes differing in the orientation of imidapril on the active site were identified, and its hydrophobic group appeared to preferentially interact with the S1 site compared with the S1' site. Compared with the lisinopril-MMP-9 model in our previous study, imidapril was stabilized effectively on the active site with less of molecular distortions. We also measured ACE and MMP-9 inhibitory activities of imidapril and lisinopril after myocardial infarction. Imidapril had a stronger inhibitory activity against MMP-9 than lisinopril. These findings show that imidapril inhibits MMP-9 directly like lisinopril and its hydrophobic interactions with the S1 site of MMP-9 would be important for enhancing inhibitory activity.

Mast cell tryptases and chymases in inflammation and host defense

Tryptases and chymases are the major proteins stored and secreted by mast cells. The types, amounts, and properties of these serine peptidases vary by mast cell subtype, tissue, and mammal of origin. Membrane-anchored gamma-tryptases are tryptic, prostasin-like, type I peptidases that remain membrane attached on release and act locally. Soluble tryptases, including their close relatives, mastins, form inhibitor-resistant oligomers that act more remotely. Befitting their greater destructive potential, chymases are quickly inhibited after release, although some gain protection by associating with proteoglycans. Most chymase-like enzymes, including mast cell cathepsin G, hydrolyze chymotryptic substrates, an uncommon capability in the proteome. Some rodent chymases, however, have mutations resulting in elastolytic activity. Secreted tryptases and chymases promote inflammation, matrix destruction, and tissue remodeling by several mechanisms, including destroying procoagulant, matrix, growth, and differentiation factors and activating proteinase-activated receptors, urokinase, metalloproteinases, and angiotensin. They also modulate immune responses by hydrolyzing chemokines and cytokines. At least one chymase protects mice from intestinal worms. Tryptases and chymases can also oppose inflammation by inactivating allergens and neuropeptides causing inflammation and bronchoconstriction. Thus, like mast cells themselves, mast cell serine peptidases play multiple roles in host defense, and any accounting of benefit versus harm is necessarily context specific.

Inhibition of matrix metalloproteinase-9 activity by lisinopril after myocardial infarction in hamsters

We measured angiotensin-converting enzyme and matrix metalloproteinase-9 activities after myocardial infarction in hamsters and compared the effects of an angiotensin-converting enzyme inhibitor lisinopril with those of an angiotensin receptor blocker candesartan cilexetil after myocardial infarction. Angiotensin-converting enzyme activity was significantly increased 3 and 7 days, but not 1 day after myocardial infarction. Matrix metalloproteinase-9 activity was significantly increased 1 day after myocardial infarction. Lisinopril significantly inhibited both angiotensin-converting enzyme and matrix metalloproteinase-9 activities, but candesartan cilexetil did not. Angiotensin-converting enzyme inhibitors might directly inhibit matrix metalloproteinase-9 activity.

The effects of chymase on matrix metalloproteinase-2 activation in neointimal hyperplasia after balloon injury in dogs

Chymase is known to generate angiotensin II in the vascular wall. In this study we investigated a novel role for chymase other than angiotensin II production in vascular proliferation after balloon injury. Chymase promoted the migration of vascular smooth muscle cells in the matrix-coated invasion chambers and activated promatrix metalloproteinase-2 obtained from the culture medium of vascular smooth muscle cells. Two weeks after balloon injury, significant neointimal formation was found in dog carotid arteries. After injury, active matrix metalloproteinase-2 was increased in parallel with the augmentation of chymase activity that was seen in the proliferating region of the vascular wall. The oral administration of NK3201 (1 mg/kg per day), a chymase inhibitor, prevented neointimal formation and significantly suppressed both active matrix metalloproteinase-2 and chymase activities 2 weeks after injury. These results suggest that chymase inhibitors can prevent the development of intimal hyperplasia via the inhibition of matrix metalloproteinase-2 activation in balloon-injured arteries.

A matrix metalloproteinase-9 activation cascade by hepatic stellate cells in trans-differentiation in the three-dimensional extracellular matrix

Hepatic stellate cells (HSCs) undergo myofibroblastic trans-differentiation in liver fibrogenesis. We previously showed that dual stimulation with three-dimensional type-I collagen and interleukin-1 (IL-1) synergistically induces HSC trans-differentiation in a manner dependent on the activation of matrix metallopreinase-9 (MMP-9). The present study is aimed to determine the mechanism of MMP-9 activation in this model. The pro-MMP-9-converting activities expressed by trans-differentiating HSCs are characterized as secreted factors that are sensitive to MMP inhibitor and have apparent molecular masses of 50 and 25 kDa. This is in sharp contrast to the pro-MMP-9 activator from mouse and human skin, which is a chymotrypsin-like proteinase. Among multiple MMPs induced in HSCs by the dual stimulation, MMP-13 is most conspicuously up-regulated and meets all criteria as the pro-MMP-9 activator. HSC cultured in three-dimensional type-I collagen, but not in Matrigel, IL-1 induces expression of MMP-13 and its matured form at 50 and 25 kDa, respectively. In vitro reconstitution experiment proves that MMP-13, but not its zymogen, activates pro-MMP-9. Further, short hairpin RNA targeting MMP-13 abolishes pro-MMP-9 activation and HSC trans-differentiation. We further demonstrate that pro-MMP-13 activation is facilitated with a membrane-associated factor, inhibited with tissue inhibitor of metalloproteinase-2, and abolished with short hairpin RNA against MMP-14. Moreover, pro-MMP-13 is also activated by a secreted factor, which is absorbed by gelatin-Sepharose and reconstituted with MMP-9. Thus, IL-1-induced trans-differentiation of HSCs in three-dimensional extracellular matrix is facilitated by an MMP activation cascade (MMP-14 > MMP-13 > MMP-9) and a positive feedback loop of MMP-9 > MMP-13, suggesting their critical roles in liver injury and repair.

Left ventricular eccentric remodeling and matrix loss are mediated by bradykinin and precede cardiomyocyte elongation in rats with volume overload

OBJECTIVES

We hypothesized that left ventricular (LV) remodeling and matrix loss in volume overload (VO) are mediated by bradykinin (BK) and exacerbated by chronic angiotensin-converting enzyme (ACE) inhibition.

BACKGROUND

Chronic ACE inhibition increases anti-fibrotic BK and does not attenuate LV remodeling in pure VO. The relative contribution of changes in extracellular matrix versus cardiomyocyte elongation in acute and chronic LV chamber remodeling during VO is unknown.

METHODS

Echocardiography, LV collagen content, and isolated cardiomyocytes were studied in rats after aortocaval fistula (ACF) of 12 h, 2 and 5 days, and 4, 8, and 15 weeks. We also studied ACF rats after BK2 receptor (BK2R) blockade (2 days) or ACE inhibition (4 weeks).

RESULTS

At 2 days after ACF, LV end-diastolic dimension (LVEDD)/wall thickness was increased, and LV interstitial collagen was decreased by 50% without cardiomyocyte elongation. The BK2R blockade prevented collagen loss and normalized LVEDD/wall thickness. From 4 to 15 weeks after ACF, interstitial collagen decreased by 30% and left ventricular end-systolic (LVES) dimension increased despite normal LVES pressure and isolated cardiomyocyte function. The ACE inhibition did not decrease LVEDD/wall thickness, further decreased LV interstitial collagen, and did not improve LV fractional shortening despite decreased LVES pressure.

CONCLUSIONS

Immediately after ACF induction, eccentric LV remodeling is mediated by interstitial collagen loss without cardiomyocyte elongation. Acute BK2R blockade prevents eccentric LV remodeling and improves function. Chronic ACE inhibition does not prevent eccentric LV remodeling or improve function. These findings suggest that ACE inhibitor-mediated increase in LV BK exacerbates matrix loss and explains why ACE inhibition is ineffective in VO.

Involvement of mast cells in the regulation of matrix metalloproteinase-9 and tissue inhibitor of metalloproteases-1 in 12-O-tetradecanoylphorbolacetate-induced inflammation in mice

In this study, we investigated the involvement of mast cells in the regulation of matrix metalloproteinase-9 (MMP-9) in 12-O-tetradecanoylphorbolacetate (TPA)-induced inflammation, using mast cell-deficient (W/W(v)) mice and control (+/+) mice. Topical application of TPA to the ears induced acute inflammation, accompanied by mast cell degranulation in +/+ mice, which peaked at 6-12 h. There was no significant difference in ear thickness between the groups until 12 h, but the swelling was greater in W/W(v) mice than +/+ mice at 24-36 h. Western blot analysis revealed that TPA-induced marked increases in levels of proMMP-9 and tissue inhibitor of metalloproteinases-1 (TIMP-1), which existed as complexes with proMMP-9. The amount of proMMP-9-TIMP-1 complex was markedly smaller in +/+ mice than W/W(v) mice at 6 and 24 h, but had almost returned to control levels in both groups at 48 h. The free form of proMMP-9 was also slightly less abundant in +/+ mice than W/W(v) mice at 6, 24, and 48 h. Gelatin zymographic analysis revealed that levels of the active species of MMP-9 (approximately 74 and 83 kD), as well as free form of proMMP-9, increased time-dependently after the application of TPA and peaked at 24 h in +/+ mice. The 74-kD band was detected only in +/+ mice at 6 h. Our results therefore suggested that during inflammation degranulation of mast cells results in a reduction of the proMMP-9-TIMP-1 complex levels, together with a fall in the amount of free proMMP-9.

Mast Cell Proteases

Mast cells (MCs) are traditionally thought of as a nuisance for its host, for example, by causing many of the symptoms associated with allergic reactions. In addition, recent research has put focus on MCs for displaying harmful effects during various autoimmune disorders. On the other hand, MCs can also be beneficial for its host, for example, by contributing to the defense against insults such as bacteria, parasites, and snake venom toxins. When the MC is challenged by an external stimulus, it may respond by degranulation. In this process, a number of powerful preformed inflammatory "mediators" are released, including cytokines, histamine, serglycin proteoglycans, and several MC-specific proteases: chymases, tryptases, and carboxypeptidase A. Although the exact effector mechanism(s) by which MCs carry out their either beneficial or harmful effects in vivo are in large parts unknown, it is reasonable to assume that these mediators may contribute in profound ways. Among the various MC mediators, the exact biological function of the MC proteases has for a long time been relatively obscure. However, recent progress involving successful genetic targeting of several MC protease genes has generated powerful tools, which will enable us to unravel the role of the MC proteases both in normal physiology as well as in pathological settings. This chapter summarizes the current knowledge of the biology of the MC proteases.

The Significance of Chymase in the Progression of Abdominal Aortic Aneurysms in Dogs

In this study, we investigated the effect of a specific chymase inhibitor, NK3201, in the progression of abdominal aortic aneurysm in a dog experimental model. Abdominal aortic aneurysms were induced in dogs by injecting elastase into the abdominal aorta. NK3201 (1 mg/kg per day, p.o.) or a placebo was started 3 days before elastase injection and continued for 8 weeks after the injection. On abdominal ultrasound, the aortic diameter was seen to gradually expand in the placebo-treated group, but not in the NK3201-treated group. Eight weeks after elastase injection, the ratio of the medial area to the total area in the placebo-treated group was significantly smaller than that in the normal group, but it was significantly larger than that in the NK3201-treated group. In addition to chymase activity, angiotensin II-forming and matrix metalloproteinase-9 activities were significantly higher in the placebo-treated group than in the normal group; in the NK3201-treated group, all of these activities were significantly decreased. On immunohistochemical analyses, there was a significantly greater number of chymase-positive cells in the placebo-treated group than in the normal group, but the number was significantly smaller in the NK3201-treated group than in the placebo-treated group. Thus, chymase inhibition may become a useful strategy for preventing abdominal aortic aneurysms.

Mast cells in diffuse large B-cell lymphoma; their role in fibrosis

AIMS

Mast cells (MCs) are associated with fibrosis in various diseases. MCs comprise two phenotypes: the MC(TC) phenotype contains tryptase and chymase, whereas the MC(T) phenotype contains tryptase. Interleukin (IL)-4 promotes the development of MC(TC) from the MC(T) phenotype. The aim of this study was to determine the relationship between MC phenotypes and fibrosis in diffuse large B-cell lymphoma (DLBCL).

METHODS AND RESULTS

We examined the distribution and density of MCs in 50 DLBCL and 20 reactive lymph nodes, and evaluated MC phenotypes and IL-4-expressing cells. To detect MCs, immunohistochemistry for tryptase and chymase was performed. The 50 DLBCLs were histologically divided into three groups: no fibrosis (32 cases), reticular type (eight cases) showing reticular fibrosis, and bundle type (10 cases) showing collagenous bundles. The density of tryptase-positive MCs was higher than that of chymase-positive MCs. The densities of tryptase-positive and chymase-positive MCs in fibrotic areas were significantly higher than those in the cellular areas in the reticular and bundle groups. Double immunostaining revealed that MCs in DLBCL comprised MC(T) and MC(TC) phenotypes. Chymase-positive MCs and T lymphocytes expressed IL-4. Although there were few chymase-positive MCs in reactive lymph nodes, the density of tryptase-positive MCs was not different from that in the 'no fibrosis' group.

CONCLUSIONS

Tryptase-positive and chymase-positive MCs are associated with fibrosis in DLBCL.

The associations between gingival crevice fluid matrix metalloproteinase-9, tissue inhibitor of metalloproteinase-1 and periodontitis in human immunodeficiency virus-positive patients

BACKGROUND AND OBJECTIVE

The study aimed to determine whether matrix metalloproteinase-9 (MMP-9) and tissue inhibitor of metalloproteinase-1 (TIMP-1) in gingival crevice fluid could serve as prognostic factors for the progression of periodontitis in human immunodeficiency virus (HIV) -positive patients. Activated inflammatory cells produce inflammatory mediators, which stimulate the production of MMPs and their inhibitors. It is likely that the compromised immune system contributes to the pathogenesis of periodontitis in HIV-positive patients.

METHODS

Clinical measurements including gingival index, plaque index, bleeding index, probing depth, attachment loss, and gingival crevice fluid samples were taken from two healthy sites (including sites with gingival recession, gingival index = 0; probing depth < or = 3 mm; attachment loss < or = 2 mm), three gingivitis sites (gingival index > 0; probing depth < or = 3 mm; attachment loss = 0) and three periodontitis sites (gingival index > 0; probing depth > or = 5 mm; attachment loss > or = 3 mm) of each of the 35 patients at baseline visits and 6-month visits by means of paper strips. Gingival crevice fluid levels of MMP-9 and TIMP-1 were determined by sandwich enzyme-linked immunosorbent assays.

RESULTS

The mean amounts of MMP-9 and TIMP-1 in the gingivitis and periodontitis sites sites were significantly higher than in the healthy sites (P < 0.0001). The progressing site was defined as a site that had 2 mm or more attachment loss during the 6-month study period. Gingival crevice fluid levels of MMP-9 were significantly correlated with probing depth, attachment loss, TIMP-1, age, smoking pack years, and viral load values at baseline and 6-month visits (0.0001 < P < 0.001). TIMP-1 levels were only correlated with CD4, viral load, attachment loss, and MMP-9 (0.001 < P < 0.01). Repeated measures analysis of 11 active sites vs. 269 inactive sites indicated that MMP-9 and TIMP-1 levels were significantly higher in active sites than in inactive sites (P < 0.0001). These data indicate that sites with high ginigval crevice fluid levels of MMP-9 and TIMP-1 in HIV-positive patients are at significantly greater risk for progression of periodontitis.

Chymase increases glomerular albumin permeability via protease-activated receptor-2

Increased infiltration of the kidney by mast cells is associated with proteinuria, and interstitial fibrosis in various renal diseases. Mast cells produce serine proteases including tryptase and chymase (MCC) that act via protease-activated receptors (PARs) to induce synthesis of fibrogenic cytokines by renal cells. In the present study, we investigated direct effect of MCC and role of PARs on glomerular albumin permeability (P(alb)). Isolated rat glomeruli were incubated with MCC (0.1, 1, 10, and 100 ng/ml) for 5-30 min in presence or absence of PAR-1 and PAR-2 blocking antibodies. P(alb) was determined from the change in glomerular volume in response to an albumin oncotic gradient. The effect of direct activation of PARs on P(alb) was verified by incubating glomeruli with synthetic hexapeptide known to activate PAR-1 and PAR-2. MCC increased P(alb) of isolated rat glomeruli in a dose- and time-dependent manner. Blocking PAR-2 prevented MCC-mediated increase in P(alb). RT-PCR analysis of glomerular RNA demonstrated the presence of constitutively expressed PAR-1, -2, and -3 and low levels of PAR-4. In addition, direct activation of PAR-2 by hexapeptide SLIGKV increased P(alb) comparable to MCC, whereas PAR-1 activation by TFLLRN had no effect on P(alb). Our results document that MCC induces increase in P(alb) and that this effect is mediated through PAR-2. MCC may also play a role in renal scarring. We propose that inhibiting MCC activity or blocking the activation of PAR-2 may provide new targets for therapy in renal diseases.

A functional comparison of canine and murine bone marrow derived cultured mast cells

Disorders involving mast cells are extremely common in dogs, ranging from allergic diseases to neoplastic transformation resulting in malignant mast cell tumors. Relatively little is known regarding the basic biologic properties of normal canine mast cells, largely due to the difficulty in reliably purifying large numbers from canine skin. In vitro generated bone marrow derived cultured mast cells (BMCMCs) are routinely used in both human and murine studies as a ready source of material for in vitro and in vivo studies. We previously developed a technique to generate canine BMCMCs from bone marrow derived CD34+ cells and demonstrated that these cells exhibit the phenotypic properties characteristic of mast cells and release histamine in response to IgE cross-linking. The purpose of the following study was to characterize the functional properties of these canine BMCMCs and contrast these with the functional properties of murine BMCMCs. Our work demonstrates that both IL-4 and IL-10 promote canine BMCMC proliferation, possibly through upregulation of Kit expression, while TGFbeta inhibits proliferation. The canine BMCMCs produce a variety of cytokines and chemokines in response to IgE cross-linking and chemical stimulation including IL-3, IL-4, IL-13, GM-CSF, RANTES, and MIP1alpha. Interestingly, the canine BMCMCs released significantly larger amounts of MCP-1 and tryptase and significantly smaller amounts of IL-6 following chemical stimulation and IgE cross-linking when compared to murine BMCMCs. Lastly, the canine BMCMCs produced larger amounts of active MMP9 than their murine counterparts. In summary, canine BMCMCs exhibit unique functional properties that distinguish them from murine BMCMCs and provide insight into the contribution of these cells to mast cell disorders in the dog.

Expansion of the mast cell chymase locus over the past 200 million years of mammalian evolution

The acidic granules of natural killer (NK) cells, T cells, mast cells, and neutrophils store large amounts of serine proteases. Functionally, these proteases are involved, e.g., in the induction of apoptosis, the recruitment of inflammatory cells, and the remodeling of extra-cellular matrix. Among the granule proteases are the phylogenetically related mast cell chymases, neutrophil cathepsin G, and T-cell granzymes (Gzm B to H and Gzm N), which share the characteristic absence of a Cys(191)-Cys(220) bridge. The genes of these proteases are clustered in one locus, the mast cell chymase locus, in all previously investigated mammals. In this paper, we present a detailed analysis of the chymase locus in cattle (Bos taurus) and opossum (Monodelphis domestica). The gained information delineates the evolution of the chymase locus over more than 200 million years. Surprisingly, the cattle chymase locus contains two alpha-chymase and two cathepsin G genes where all other studied chymase loci have single genes. Moreover, the cattle locus holds at least four genes for duodenases, which are not found in other chymase loci. Interestingly, duodenases seem to have digestive rather than immune functions. In opossum, on the other hand, only two chymase locus-related genes have been identified. These two genes are not arranged in one locus, but appear to have been separated by a marsupial-specific chromosomal rearrangement. Phylogenetic analyses place one of the opossum genes firmly with mast cell alpha-chymases, which indicates that the alpha-chymase had already evolved as a separate, clearly identifiable gene before the separation of marsupials and placental mammals. In contrast, the second gene in opossum is positioned phylogenetically between granzymes, cathepsin G, and the duodenases. These genes, therefore, probably evolved as separate subfamilies after the separation of placental mammals from marsupials. In platypus, only one chymase locus-like sequence could be identified. This previously published "granzyme" does not cluster clearly with any of the chymase locus gene families, but shares the absence of the Cys(191)-Cys(220) bridge with the other chymase locus proteases. These findings indicate that all chymase locus genes are derived from a single ancestor that was present more than 200 million years ago.

Generation and characterization of bone marrow-derived cultured canine mast cells

Disorders of mast cells, particularly mast cell tumors (MCTs), are common in dogs. There now is evidence that many of these disorders exhibit breed predilections, suggesting an underlying heritable component. In comparison to humans and mice, little is known regarding the biology of canine mast cells. To facilitate the study of mast cell biology in other species, bone marrow-derived cultured mast cells (BMCMCs) often are used because these represent a ready source of large numbers of cells. We have developed a protocol to successfully generate canine BMCMCs from purified CD34(+) cells. After 5-7 weeks of culture with recombinant canine stem cell factor (rcSCF), greater than 90% of the cell population consisted of mast cells as evidenced by staining with Wright's-Giemsa, as well as production of chymase, tryptase, IL-8 and MCP-1. These cells expressed cell surface markers typical of mast cells including Kit, Fc epsilonRI, CD44, CD45 and CD18/CD11b. The canine BMCMCs were dependent on rcSCF for survival and proliferation, and migrated in response to rcSCF gradients. Cross-linking of cell surface-bound IgE induced the release of histamine and TNFalpha. Histamine release could also be stimulated by ConA, compound 48/80, and calcium ionophore. In summary, canine BMCMCs possess phenotypic and functional properties similar to mast cells found in vivo. These cells represent a novel, valuable resource for investigating normal canine mast cell biology as well as for identifying factors that lead to mast cell dysregulation in the dog.

Mast cell chymase induces expression of chemokines for neutrophils in eosinophilic EoL-1 cells and mouse peritonitis eosinophils

Human chymase induced release of interleukin-8 (IL-8) in human EoL-1 cells that had been differentiated into eosinophil-like cells with butyric acid. The chymase-induced IL-8 production was specific in that other cytokines/chemokines examined were not induced. Human chymase also increased mRNA for IL-8 in the differentiated EoL-1 cells, showing involvement of mRNA synthesis. The chymase-induced IL-8 release was inhibited by pertussis toxin as well as U0126 (an inhibitor for extracellular signal-regulated kinase pathway) and SB203580 (p38 inhibitor), suggesting that the chymase-induced IL-8 production is mediated by G protein-coupled receptor and mitogen-activated protein kinases. Mouse mast cell protease-4 (mMCP-4), a mouse chymase, induced macrophage-inflammatory protein-2 (MIP-2), a mouse homologue for IL-8, in mouse eosinophils in vitro. Intradermal injection of mMCP-4 not only induced skin edema but increased MIP-2 content and neutrophil number at the injection site. Taken together, our findings demonstrate that mast cell chymase may contribute to the interaction between eosinophils and neutrophils by inducing IL-8/MIP-2 in eosinophils at allergic inflamed sites.

Expression of chymase-positive cells in gastric cancer and its correlation with the angiogenesis

BACKGROUND AND OBJECTIVES

Chymase is expressed in mast cells and induces angiogenesis via activation of angiotensin II and matrix metalloproteinase-9. However, it has been unclear whether chymase is involved in the pathophysiology of angiogenesis in gastric cancer. To clarify the contribution of chymase to angiogenesis in gastric cancer, we assessed the relationship between chymase-positive cells and tumor angiogenesis.

METHODS

We evaluated chymase-positive cells and microvessels using anti-human chymase and anti-CD34 antibodies in 168 cases of gastric cancer, respectively.

RESULTS

Chymase-positive cells in gastric tumor region were significantly higher than the cells in normal region. The number of chymase-positive cells in the undifferentiated type of gastric tumor region was significantly higher than the one in the differentiated type. Specimens from patients with advanced histological stages of disease had more chymase-positive cells than those with early-stage disease. There was a significant positive correlation between chymase-positive cells and microvessels in gastric cancer specimens. Postoperative survival curves revealed that patients with a high number of chymase-positive cells had a poor prognosis.

CONCLUSIONS

These results suggest that accumulation of chymase-positive cells in gastric cancer may lead to an increase of tumor angiogenesis, and may contribute to tumor growth and progression.

Mast cell-dependent activation of pro matrix metalloprotease 2: a role for serglycin proteoglycan-dependent mast cell proteases

The formation of active matrix metalloprotease-2 (MMP-2) requires the proteolytic processing of proMMP-2, a process that can occur through the formation of a ternary complex between proMMP-2, the tissue inhibitor of metalloprotease-2 and membrane type 1-MMP. However, other activation mechanisms have been suggested, and in this study we investigated whether mast cells (MCs) may play a role in the activation of proMMP-2. Murine peritoneal cells, a mixture of macrophages, lymphocytes and MCs, were cultured ex vivo. Addition of proMMP-2 to resting peritoneal cell cultures resulted in only slow conversion of proMMP-2 into the active enzyme. However, when MC degranulation was provoked using a calcium ionophore, proMMP-2 processing was markedly enhanced. When the peritoneal cell populations were depleted in MCs, proMMP-2 processing was abrogated, but was reconstituted when purified MCs were added to the depleted cultures. ProMMP-2 processing was sensitive to serine protease inhibitors, but not to inhibitors of other classes of proteases. Furthermore, proMMP-2 processing was completely abrogated in cells lacking serglycin, a proteoglycan that has previously been shown to mediate storage of a variety of MC serine proteases. Taken together, these results suggest a novel mode of proMMP-2 activation mediated by serglycin-dependent MC serine proteases.

c-Kit immunophenotyping and metalloproteinase expression profiles of mast cells in interstitial lung diseases

Diverse interstitial lung diseases (ILD) demonstrate mesenchymal infiltration by an abundance of activated mast cells whose role in parenchymal fibrogenesis remains unclear. Since mast cells differentiate in a dynamic, tissue-specific manner via signals transduced by c-Kit receptor, we examined the effect of ILD microenvironments on c-Kit expression and metalloproteinase phenotypes of mesenchymal mast cell populations. Immunohistochemical and flow cytometric analyses characterized surface expression of c-Kit on mast cells in tissues obtained from patients with idiopathic pulmonary fibrosis, systemic sclerosis, sarcoidosis, and lymphangioleiomyomatosis, thus identifying a unique immunophenotype not shared by normal lung mast cells. Isolation of c-Kit+/FcepsilonRI+/CD34- mast cells via immunocytometric sorting of heterogeneous cell populations from mechanically disaggregated lung tissues permitted analysis of gene expression patterns by two-step real-time polymerase chain reaction. Transcriptional profiling identified expression of c-Kit and the neutral serine proteases, tryptase and chymase, establishing the identity of sorted populations as mature mast cells. Mast cells harvested from ILD tissues demonstrated characteristic metalloproteinase phenotypes which included expression of matrix metalloproteinase (MMP)-1 and a disintegrin and metalloproteinase (ADAM)-9, -10, and -17. Immunohistochemical co-localization guided by gene profiling data confirmed expression of chymase, MMP-1, and ADAM-17 protein in subpopulations of mast cells in remodelling interstitium. Gene profiling of harvested mast cells also showed increased transcript copy numbers for TNFalpha and CC chemokine receptor 2, which play critical roles in lung injury. We conclude that ILD microenvironments induce unique c-Kit receptor and metalloproteinase mast cell phenotypes.

Current controversies in oral lichen planus: Report of an international consensus meeting. Part 1. Viral infections and etiopathogenesis

Despite recent advances in understanding the immunopathogenesis of oral lichen planus (LP), the initial triggers of lesion formation and the essential pathogenic pathways are unknown. It is therefore not surprising that the clinical management of oral LP poses considerable difficulties to the dermatologist and the oral physician. A consensus meeting was held in France in March 2003 to discuss the most controversial aspects of oral LP. Part 1 of the meeting report focuses on (1) the relationship between oral LP and viral infection with special emphasis on hepatitis C virus (HCV), and (2) oral LP pathogenesis, in particular the immune mechanisms resulting in lymphocyte infiltration and keratinocyte apoptosis. Part 2 focuses on patient management and therapeutic approaches and includes discussion on malignant transformation of oral LP.

Characterization of mast cell subpopulations in lip cancer

BACKGROUND

Lip squamous cell carcinoma (SCC) is the most common form of oral cancer. Human mast cells (MCs), which are increased in lip SCC, are classified by their protease content in tryptase-positive (MC(T)) and tryptase/chymase-positive (MC(TC)). MC proteases are associated with tumor progression and angiogenesis. The aim of this study was to quantify and characterize MC subpopulations in lip SCC.

METHODS

Serial sections from lip SCC (n = 21) and normal lip vermilion (n = 8) biopsies were stained immunohistochemically for tryptase and enzymehistochemically for chymase to determine MC subpopulation density and distribution.

RESULTS

MC(T) and MC(TC) were increased in lip SCC when compared with normal lip (P < 0.0001), where MC(T) predominated over MC(TC) (P < 0.01). In lip SCC neither subpopulation predominated. Regarding distribution, MC(T) were higher than MC(TC) at the intratumoral stroma, whereas MC(TC) were higher than MC(T) at the peritumoral stroma (P < 0.01).

CONCLUSIONS

The results suggest that MC subpopulations may contribute to lip SCC progression. While intratumoral MC(T) may stimulate angiogenesis, peritumoral MC(TC) may promote extracellular matrix degradation and tumor progression at the invasion front.

MMP-1 activation by serine proteases and MMP-10 induces human capillary tubular network collapse and regression in 3D collagen matrices

Previous work has shown that endothelial cell (EC)-derived matrix metalloproteinases (MMPs) regulate regression of capillary tubes in vitro in a plasmin- and MMP-1 dependent manner. Here we report that a number of serine proteases can activate MMP-1 and cause capillary tube regression; namely plasma kallikrein, trypsin, neutrophil elastase, cathepsin G, tryptase and chymase. Plasma prekallikrein failed to induce regression without coactivators such as high molecular weight kininogen (HMWK) or coagulation Factor XII. The addition of trypsin, the neutrophil serine proteases (neutrophil elastase and cathepsin G) and the mast cell serine proteases (tryptase and chymase) each caused MMP-1 activation and collagen type I proteolysis, capillary tubular network collapse, regression and EC apoptosis. Capillary tube collapse is accompanied by collagen gel contraction, which is strongly related to the wound contraction that occurs during regression of granulation tissue in vivo. We also report that proMMP-10 protein expression is markedly induced in ECs undergoing capillary tube morphogenesis. Addition of each of the serine proteases described above led to activation of proMMP-10, which also correlated with MMP-1 activation and capillary tube regression. Treatment of ECs with MMP-1 or MMP-10 siRNA markedly delayed capillary tube regression, whereas gelatinase A (MMP-2), gelatinase B (MMP-9) and stromelysin-1 (MMP-3) siRNA-treated cells behaved in a similar manner to controls and regressed normally. Increased expression of MMP-1 or MMP-10 in ECs using recombinant adenoviral delivery markedly accelerated serine protease-induced capillary tube regression. ECs expressing increased levels of MMP-10 activated MMP-1 to a greater degree than control ECs. Thus, MMP-10-induced activation of MMP-1 correlated with tube regression and gel contraction. In summary, our work demonstrates that MMP-1 zymogen activation is mediated by multiple serine proteases and MMP-10, and that these events are central to EC-mediated collagen degradation and capillary tube regression in 3D collagen matrices.

Gelatinase-mediated migration and invasion of cancer cells

The matrix metalloproteinases(MMP)-2 and -9, also known as the gelatinases have been long recognized as major contributors to the proteolytic degradation of extracellular matrix during tumor invasion. In the recent years, a plethora of non-matrix proteins have also been identified as gelatinase substrates thus significantly broadening our understanding of these enzymes as proteolytic executors and regulators in various physiological and pathological states including embryonic growth and development, angiogenesis and tumor progression, inflammation, infective diseases, degenerative diseases of the brain and vascular diseases. Although the effect of broad-spectrum inhibitors of MMPs in the treatment of cancer has been disappointing in clinical trials, novel mechanisms of gelatinase inhibition have been now identified. Inhibition of the association of the gelatinases with cell-surface integrins appears to offer highly specific means to target these enzymes without inhibiting their catalytic activity in multiple cell types including endothelial cells, tumor cells and leukocytes. Here, we review the multiple functions of the gelatinases in cancer, and especially their role in the tumor cell migration and invasion.

Synergy between a plasminogen cascade and MMP-9 in autoimmune disease

Extracellular proteolysis by the plasminogen/plasmin (Plg/plasmin) system and MMPs is required for tissue injury in autoimmune and inflammatory diseases. We demonstrate that a Plg cascade synergizes with MMP-9/gelatinase B in vivo during dermal-epidermal separation in an experimental model of bullous pemphigoid (BP), an autoimmune disease. BP was induced in mice by antibodies to the hemidesmosomal antigen BP180. Mice deficient in MMP-9 were resistant to experimental BP, while mice deficient in Plg and both tissue Plg activator (tPA) and urokinase Plg activator (uPA) showed delayed and less intense blister formation induced by antibodies to BP180. Plg-deficient mice reconstituted locally with Plg or the active form of MMP-9 (actMMP-9), but not the proenzyme form of MMP-9 (proMMP-9), developed BP. In contrast, proMMP-9 or actMMP-9, but not Plg, reconstituted susceptibility of MMP-9-deficient mice to the skin disease. In addition, MMP-3-deficient mice injected with pathogenic IgG developed the same degree of BP and expressed levels of actMMP-9 in the skin similar to those of WT controls. Thus, the Plg/plasmin system is epistatic to MMP-9 activation and subsequent dermal-epidermal separation in BP.

A Key Role for Mast Cell Chymase in the Activation of Pro-matrix Metalloprotease-9 and Pro-matrix Metalloprotease-2

Chymases, serine proteases exclusively expressed by mast cells, have been implicated in various pathological conditions. However, the basis for these activities is not known, i.e. the in vivo substrate(s) for mast cell chymase has not been identified. In this study we show that mice lacking the chymase mouse mast cell protease 4 (mMCP-4) fail to process pro-matrix metalloprotease 9 (pro-MMP-9) to its active form in vivo, whereas both the pro and active form of MMP-9 was found in tissues of wild type mice. Moreover, the processing of pro-MMP-2 into active enzyme was markedly defective in mMCP-4 null animals. Histological analysis revealed an increase in collagen in the ear tissue of mMCP-4-deficient animals accompanied by increased ear thickness and a higher content of hydroxyproline. Furthermore, both lung and ear tissue from the knock-out animals showed a markedly increased staining for fibronectin. MMP-9 and MMP-2 are known to have a range of important activities, but the mechanisms for their activation in vivo have not been clarified previously. The present study thus indicates a key role for mast cell chymase in the regulation of pro-MMP-2 and -9 activities. Moreover, the results suggest an important role for mast cell chymase in regulating connective tissue homeostasis.

Mast cell tryptase may modulate endothelial cell phenotype in healing myocardial infarcts

Mast cells and macrophages infiltrate healing myocardial infarcts and may play an important role in regulating fibrous tissue deposition and extracellular matrix remodelling. This study examined the time-course of macrophage and mast cell accumulation in healing infarcts and studied the histological characteristics and protease expression profile of mast cells in a canine model of experimental infarction. Although macrophages were more numerous than mast cells in infarct granulation tissue, macrophage density decreased during maturation of the scar, whereas mast cell numbers remained persistently elevated. During the inflammatory phase of infarction, newly recruited leucocytes infiltrated the injured myocardium and appeared to be clustered in close proximity to degranulating cardiac mast cells. During the proliferative phase of healing, mast cells had decreased granular content and were localized close to infarct neovessels. In contrast, macrophages showed no selective localization. Mast cells in healing canine infarcts were alcian blue/safranin-positive cells that expressed both tryptase and chymase. In order to explain the pro-inflammatory and angiogenic actions of tryptase--the major secretory protein of mast cells--its effects on endothelial chemokine expression were examined. Chemokines are chemotactic cytokines that play an important role in leucocyte trafficking and angiogenesis and are highly induced in infarcts. Tryptase, a proteinase-activated receptor (PAR)-2 agonist, induced endothelial expression of the angiogenic chemokines CCL2/MCP-1 and CXCL8/IL-8, but not the angiostatic chemokine CXCL10/IP-10. Endothelial PAR-2 stimulation with the agonist peptide SLIGKV induced a similar chemokine expression profile. Mast cell tryptase may exert its angiogenic effects in part through selective stimulation of angiogenic chemokines.

Upregulation of matrix metalloproteinases following nerve injury is not mediated by mast cell activation

OBJECTIVE

Matrix metalloproteinases (MMPs) contribute to inflammatory and degenerative processes in injured nerves. Since mast cells release mediators which upregulate and activate MMPs, we tested the hypothesis that activation of mast cells is responsible for changes in the expression and activity of MMP-2 and MMP-9 in the injured peripheral nerve.

METHODS

The sciatic nerve was partially ligated in Wistar rats in which mast cells were stabilized with sodium cromoglycate. Expression and activity of MMP-2 and MMP-9 were measured in the injured and contralateral nerve using gelatin zymography, and compared between mast cell-stabilized and control groups.

RESULTS

Expression and activity of MMP-9 were increased in both the injured and contralateral nerve, but activity of MMP2 was slightly reduced by nerve injury. However, stabilization of mast cells did not alter the changes in expression or activity of MMP-2 and MMP-9 following nerve injury.

CONCLUSION

These findings suggest that the contribution of MMP-9 upregulation to the inflammatory and degenerative changes that follow nerve injury is independent of mast cell activation.

Chymase as a novel target for the prevention of vascular diseases

In vascular tissues, chymase catalyzes the production of angiotensin II, which plays a crucial role in vascular diseases. Recent clinical studies and animal models of vascular proliferation and atherosclerosis have provided evidence that angiotensin II formed by chymase is involved in these processes. These observations suggest that chymase might promote the development of vascular proliferation and atherosclerosis. Chymase also activates matrix metalloproteinase 9, which promotes aortic aneurysm and angiogenesis, and thus chymase inhibitors might also prevent the progression of abdominal aortic aneurysm and angiogenesis. We propose that chymase is a novel target for preventing vascular diseases.

The tumor microenvironment: a critical determinant of neoplastic evolution

Evolution of neoplastic cells has generally been regarded as a cumulative intrinsic process resulting in altered cell characteristics enabling enhanced growth properties, evasion of apoptotic signals, unlimited replicative potential and gain of properties enabling the ability to thrive in ectopic tissues and in some cases, ability to metastasize. Recently however, the role of the neoplastic microenvironment has become appreciated largely due to the realization that tumors are not merely masses of neoplastic cells, but instead, are complex tissues composed of both a non-cellular (matrix proteins) and a cellular 'diploid' component (tumor-associated fibroblasts, capillary-associated cells and inflammatory cells), in addition to the ever-evolving neoplastic cells. With these realizations, it has become evident that early and persistent inflammatory responses observed in or around many solid tumors, play important roles in establishing an environment suitable for neoplastic progression by providing diverse factors that alter tissue homeostasis. Using cutaneous melanoma and squamous cell carcinoma as tumor models, we review the current literature focussing on inflammatory and tumor-associated fibroblast responses as critical mediators of neoplastic progression for these malignancies.

Mast cells--a role in periodontal diseases?

OBJECTIVES

Limited attention has been given to the role mast cells may play in periodontal diseases.

BACKGROUND

Mast cells are indeed found abundantly below and within several types of mucosal epithelia. On the basis of their proteinase content, mast cells are divided into connective tissue (CT) and mucosal phenotypes. The CT phenotype contains both tryptase and chymase (MC(TC)), while the mucosal phenotype contains only tryptase (MC(T)). The in vivo significance of different mast cell phenotypes has not yet been fully established. Mast cells are able to phagocytose, process and present antigens as effectively as macrophages.

RESULTS

Recently mast cells were found in high numbers in chronically inflamed gingival tissue taken from patients with chronic marginal periodontitis (CMP). The number of mast cells was found to be even higher in HIV(+) patients with CMP. Furthermore, mast cells also express strongly matrix metalloproteinases (MMPs), which are key enzymes in degradation of gingival extracellular matrix. Mast cells may release preformed cytokines directing local innate and adaptive immune responses. The present review will focus on possible roles for mast cells in periodontal diseases.

CONCLUSIONS

We certainly feel that this is a key cell in inflamed periodontal tissue and its role in periodontitis needs to be revisited.

Involvement of mast cell chymase in bleomycin-induced pulmonary fibrosis in mice

The possible role of mast cell chymase in organ fibrosis was examined using a bleomycin-induced pulmonary fibrosis model in mice. Intratracheal injection of bleomycin to mice significantly increased not only hydroxyproline content but also chymase activity in the lung. Administration of a chymase inhibitor SUN C8077 (7-chloro-3-(3-amynophenyl) quinazoline-2, 4-dione methanesulfonate) dose-dependently reversed the bleomycin-induced increase in hydroxyproline content as well as chymase activity in the lung. Human chymase digested latent transforming growth factor-beta1 (TGF-beta1) to form mature TGF-beta1 in vitro, which was inhibited by SUN C8077. Human chymase, on the other hand, failed to stimulate DNA synthesis of human lung fibroblasts CCD-8Lu and LL97A. Taken together, it is suggested that mast cell chymase might participate in the pathogenesis of pulmonary fibrosis, and that the chymase-induced fibrosis might be mediated at least in part by TGF-beta1. Chymase inhibitor may be promising for treatment of pulmonary fibrosis in humans.

Immune activation and chronic inflammation as the cause of malignancy in oral lichen planus: is there any evidence ?

The association of chronic inflammation with a variety of epithelial malignancies has been recognised for centuries. Well established examples include, among many others, oesophageal adenocarcinoma associated with chronic oesophagitis and bowel cancer associated with chronic inflammatory bowel diseases. By now no data, other than clinical observation, have been available in understanding the pathogenesis of these inflammation-related tumours. However, recent molecular studies on the relationship between solid malignancies and the surrounding stroma have given new insights. There is now enough evidence to accept that the chronic inflammatory process per se is able to provide a cytokine-based microenvironment which is able to influence cell survival, growth, proliferation, differentiation and movement, hence contributing to cancer initiation, progression, invasion and metastasis. Here it is discussed whether also oral lichen planus (OLP), being a chronic inflammatory autoimmune disease which has been clinically associated with development of oral squamous cell carcinoma, might be categorised among these disorders. With this aim, we critically reviewed and detailed the presence, in OLP subepithelial infiltrate, of inflammatory cells and cytokine networks that might act to promote squamous tumorigenesis.

IgE crosslinkage of Fcε receptor I induces both production and activation of matrix metalloproteinase-9 in mast cells

Since mast cells play pivotal roles in allergic inflammations, we investigated how IgE-mediated stimulation modulated mast cell matrix metalloproteinase (MMP)-9 production, and its enzymatic activation. In this study, we clearly demonstrated that proMMP-9 released from murine bone marrow-derived cultured mast cells (BMCMC) was activated to its valid form after crosslinking of surface immunoglobulin (Ig)E. Serine protease inhibitors sensitive to chymases inhibited the phenomenon, indicating that certain chymases may be responsible for activation of proMMP-9. Although binding of IgE to its specific receptors did not alter MMP-9 production, the IgE crosslinkage increased both expression of mRNA, and production of MMP-9 in mast cells. Glucocorticoid declined extra cellular processing of proMMP-9 without affecting mRNA expression. These findings give rise to the possibility that production and activation of mast cell MMP-9 may be increased in the affected sites, thereby resulting in an exacerbation of tissue degradation in inflammatory conditions.

Anoikis in the cardiovascular system: known and unknown extracellular mediators

Anoïkis is defined as programmed cell death induced by the loss of cell/matrix interactions. Adhesion to structural glycoproteins of the extracellular matrix is necessary for survival of the differentiated adherent cells in the cardiovascular system, including endothelial cells, smooth muscle cells, fibroblasts, and cardiac myocytes. Adhesion is also a key factor for the differentiation of mesenchymal stem cells. In particular, fibronectin is considered a factor of survival and differentiation for many adherent cells. Adhesion generates cell tensional integrity (tensegrity) and repression of apoptotic signals, whereas detachment has the opposite effect. Anoïkis plays a physiological role by regulating cell homeostasis in tissues. However, anoïkis can also be involved in pathological processes, as illustrated by the resistance to anoïkis in cancer and its enhancement in degenerative tissue remodeling. Extracellular mediators of anoïkis include matrix retraction, leading to loss of tensegrity in fibroblasts, pharmacological disengagement of integrins by RGD-like peptides and fragments of fibronectin, and focal adhesion disassembly by fragments of thrombospondin, plasminogen activator-1, and high-molecular-weight kininogen. In addition to binding of the RGD peptide by integrins, the engagement of the heparin binding sites of adhesive glycoproteins with glycosaminoglycans on the cell surface is also involved in the prevention of cell detachment-induced apoptosis. Proteases able to degrade adhesive glycoproteins, such as fibronectin, induce anoïkis of vascular adherent cells. Active proteases can either be secreted directly by inflammatory cells, as elastase and cathepsin G by polymorphonuclear leukocytes, chymase and tryptase by mast cells, and granzymes by lymphocytes, or generated from circulating zymogens by activation in close contact with the cells. This is the case for the pericellular conversion of plasminogen to plasmin, which degrades fibronectin and induces anoïkis of smooth muscle cells. Involvement of proteases has also been proposed in the apoptotic response of cultured adherent cells to serum starvation. Anoïkis is probably involved in pathological remodeling of cardiovascular tissues, including cardiac myocyte detachment in heart failure, deendothelialization and plaque rupture in atherosclerosis, and smooth muscle cell disappearance in aneurysms and varicose veins. The absence of cell adhesion and growth resulting from cleavage of adhesive proteins also represents a major impediment to cellular healing, including the absence of cell recolonization of proteolytically injured tissue and the low efficacy of cell transplantation. However, the exact role of anoïkis in cardiovascular pathologies remains to be further defined.

Chymase-positive mast cells in small sized adenocarcinoma of the lung

Mast cells accumulate in angiogenesis-dependent situations of lung adenocarcinoma. Human mast cells are divided into two major subsets: MCT (mast cells with immunoreactivity for tryptase but not chymase) and MCTC (reactive for tryptase and chymase). Chymase is an important mediator of tissue remodeling, but research into chymase-containing mast cell subpopulations has been hampered by the lack of reagents suitable for use with formalin-fixed tissue. We stained chymase using CC1 antibody in 66 cases of small sized lung adenocarcinoma as well as CD34 and tryptase. There were significant positive correlations of microvessel counts with MCT-type and MCTC-type mast cell counts in lung adenocarcinomas. When analyzed according to Noguchi's classification, MCT-type and MCTC-type mast cells were significantly increased in Noguchi type-C tumors [localized bronchioloalveolar carcinoma (LBAC) with active fibroblastic proliferation] compared with in Noguchi type-A (LBAC) plus type-B tumors (LBAC with alveolar collapse). Members in the high-count group of MCTC-type but not MCT-type mast cells showed a significantly worse outcome than those in the low-count group in LBACs. Counting chymase-positive (MCTC-type) mast cells in tumor stroma may be a good prognosis predictor for LBACs, especially Noguchi type-C tumors.

Cardiac interstitial bradykinin and mast cells modulate pattern of LV remodeling in volume overload in rats

In the current study, interstitial fluid (ISF), bradykinin (BK), and angiotensin II (ANG II) levels were measured using cardiac microdialysis in conscious, nonsedated rats at baseline and at 48 h and 5 days after each of the following: sham surgery (sham, n = 6), sham + administration of ANG-converting enzyme inhibitor ramipril (R, n = 6), creation of aortocaval fistula (ACF, n = 6), ACF + R (n = 6), and ACF + R + BK2 receptor antagonist (HOE-140) administration (n = 6). At 5 days, both ISF ANG II and BK increased in ACF rats (P < 0.05); however, in ACF + R rats, ISF ANG II did not differ from basal levels and ISF BK increased greater than threefold above baseline at 2 and 5 days (P < 0.05). Five days after ACF, the left ventricular (LV) weight-to-body weight ratio increased 30% (P < 0.05) in ACF but did not differ from sham in ACF + R and ACF + R + HOE-140 rats despite similar systemic arterial pressures across all ACF groups. However, ACF + R + HOE-140 rats had greater postmortem wall thickness-to-diameter ratio and smaller cross-sectional diameter compared with ACF + R rats. There was a significant increase in mast cell density in ACF and ACF + R rats that decreased below sham in ACF + R + HOE-140 rats. These results suggest a potentially important interaction of mast cells and BK in the cardiac interstitium that modulates the pattern of LV remodeling in the acute phase of volume overload.

[Detections of matrix metalloproteinases activities and localization by film in situ zymography (FIZ)]

Extracellular proteolysis is an essential process for cell migration in several diseases such as tumor invasion, metastasis, and angiogenesis. In an invasive process, matrix metalloproteinases (MMPs) play a central role as degradation enzymes of extracellular matrix. Immunohistochemical staining (IHC) or ELISA methods have been carried out for the detection of tissue MMP proteins, and MMP activities have been mainly measured by gelatin zymography. Recently, film in situ zymography (FIZ) was developed for the regional detection of tissue MMP activities. FIZ uses a polyester film coated with gelatin uniformly and thinly. Frozen sections are incubated on the film at 37 degrees for optimal time. After gelatin staining with Biebrich Scarlet, the unstained area corresponds to MMP activities. The regional detection of tissue MMP activities by FIZ is simple and quantitative, and it is a useful tool for the studies of many diseases involving MMP. The detection of precise localization of MMP activity in tissues by FIZ may contribute the new classification of diseases involving MMP.

Epithelial carcinogenesis: dynamic interplay between neoplastic cells and their microenvironment

Matrix metalloproteinases (MMPs) have long been thought of as critical factors regulating matrix degradation associated with cell invasion into ectopic tissue compartments during primary tumor growth and metastasis. One member of the MMP family historically linked to these invasive processes is MMP-9/gelatinase B. By studying a transgenic mouse model of de novo epithelial carcinogenesis, new roles for MMP-9 have emerged that broaden the view of its functional contribution to malignant progression. The combined implication of these studies suggest that MMP-9 functionally contributes to cancer development; however, its major regulatory role may be in its ability to activate poorly diffusible and/or matrix-sequestered growth factors that regulate epithelial and/or endothelial cell growth as opposed to regulating cellular invasion across basement membranes.