In vivo localization of gelatinases (MMP-2 and -9) by in situ zymography with a selective gelatinase inhibitor

Epithelial barrier and oral bacterial infection

The oral epithelial barrier separates the host from the environment and provides the first line of defense against pathogens, exogenous substances and mechanical stress. It consists of underlying connective tissue and a stratified keratinized epithelium with a basement membrane, whose cells undergo terminal differentiation resulting in the formation of a mechanically resistant surface. Gingival keratinocytes are connected by various transmembrane proteins, such as tight junctions, adherens junctions and gap junctions, each of which has a specialized structure and specific functions. Periodontal pathogens are able to induce inflammatory responses that lead to attachment loss and periodontal destruction. A number of studies have demonstrated that the characteristics of pathogenic oral bacteria influence the expression and structural integrity of different cell-cell junctions. Tissue destruction can be mediated by host cells following stimulation with cytokines and bacterial products. Keratinocytes, the main cell type in gingival epithelial tissues, express a variety of proinflammatory cytokines and chemokines, including interleukin-1alpha, interleukin-1beta, interleukin-6, interleukin-8 and tumor necrosis factor-alpha. Furthermore, the inflammatory mediators that may be secreted by oral keratinocytes are vascular endothelial growth factor, prostaglandin E2 , interleukin-1 receptor antagonist and chemokine (C-C motif) ligand 2. The protein family of matrix metalloproteinases is able to degrade all types of extracellular matrix protein, and can process a number of bioactive molecules. Matrix metalloproteinase activities under inflammatory conditions are mostly deregulated and often increased, and those mainly relevant in periodontal disease are matrix metalloproteinases 1, 2, 3, 8, 9, 13 and 24. Viral infection may also influence the epithelial barrier. Studies show that the expression of HIV proteins in the mucosal epithelium is correlated with the disruption of epithelial tight junctions, suggesting a possible enhancement of human papilloma virus infection by HIV-associated disruption of tight junctions. Altered expression of matrix metalloproteinases was demonstrated in keratinocytes transformed with human papilloma virus-16 or papilloma virus-18,. To summarize, the oral epithelium is able to react to a variety of exogenous, possibly noxious influences.

Mechanisms of Renal Vasodilation and Hyperfiltration During Pregnancy

Glomerular filtration rate (GFR) and renal plasma flow (RPF) increase by 40-65% and 50-85%, respectively, during normal pregnancy in women. Studies using the gravid rat as a model have greatly enhanced our understanding of mechanisms underlying these remarkable changes in the renal circulation during gestation. Hyperfiltration appears to be almost completely due to the increase in RPF, the latter attributable to profound reductions in both the renal afferent and efferent arteriolar resistances. The major pregnancy hormone involved is relaxin. The mediators downstream from relaxin include endothelin (ET) and nitric oxide (NO). New evidence indicates that relaxin increases vascular gelatinase activity during pregnancy, thereby converting big ET to ET(1-32), which leads to renal vasodilation, hyperfiltration, and reduced myogenic reactivity of small renal arteries via the endothelial ET(B) receptor and NO. Whether the chronic volume expansion characteristic of pregnancy contributes to the maintenance of gestational renal changes requires further investigation. Additional studies are also needed to further delineate the molecular basis of these mechanisms and, importantly, to investigate whether they apply to women.

Intracellular MMP-2 activity in skeletal muscle is associated with type II fibers

Matrix metalloproteinase 2 (MMP-2) is a proteolytic enzyme implicated in motility, differentiation, and regeneration of skeletal muscle fibers through processing of extracellular substrates. Although MMP-2 has been found to be localized intracellularly in cardiomyocytes where the enzyme is thought to contribute to post-ischemic loss of contractility, little is known about intracellular MMP-2 activity in skeletal muscle fibers. In the present study we demonstrate intracellular MMP-2 in normal skeletal muscle by immunohistochemical staining. Immunogold electron microscopic analyses indicated that the enzyme was concentrated in Z-lines of the sarcomers, in the nuclear membrane, and in mitochondria. By use of in situ zymography, we found that gelatinolytic activity in muscle fibers was co-localized with immunofluorecent staining for MMP-2. Staining for MMP-9, the other member of the gelatinase group of the MMPs, was negative. The broad-spectrum metalloprotease inhibitor EDTA and the selective gelatinase inhibitor CTT2, but not the cysteine inhibitor E64, strongly reduced the gelatinolytic activity. The intracellular gelatinolytic activity was much more prominent in fast twitch type II fibers than in slow twitch type I fibers, and there was a decrease in intracellular gelatinolytic activity and MMP-2 expression in muscles from mice exposed to high intensity interval training. Together our results indicate that MMP-2 is part of the intracellular proteolytic network in normal skeletal muscle, especially in fast twitch type II fibers. Further, the results suggest that intracellular MMP-2 in skeletal muscle fibers is active during normal homeostasis, and affected by the level of physical activity.

Tumor cell responses to carbon dots derived from chondroitin sulfate

Photoluminescent carbon dots (CDs) derived from chondroitin sulfate (CS) showing multifunctional behavior: cell imaging and cell proliferative responses.

Fluctuating roles of matrix metalloproteinase-9 in oral squamous cell carcinoma

One hallmark of cancer is the degradation of the extracellular matrix (ECM), which is caused by proteinases. In oral cancers, matrix metalloproteinases (MMPs), especially MMP-9, are associated with this degradation. MMPs break down the ECM allowing cancer to spread; they also release various factors from their cryptic sites, including cytokines. These factors modulate cell behavior and enhance cancer progression by regulating angiogenesis, migration, proliferation, and invasion. The development of early metastases is typical for oral cancer, and increased MMP-9 expression is associated with a poor disease prognosis. However, many studies fail to relate MMP-9 expression with metastasis formation. Contrary to earlier models, recent studies show that MMP-9 plays a protective role in oral cancers. Therefore, the role of MMP-9 is complicated and may fluctuate throughout the different types and stages of oral cancers.

Targeting gelatinases with a near-infrared fluorescent cyclic His-Try-Gly-Phe peptide

PURPOSE

The purpose of the study is to synthesize and characterize near-infrared (NIR) fluorescence imaging probes targeted to gelatinases.

PROCEDURES

A phage display-selected cyclic peptide containing the His-Try-Gly-Phe (HWGF) motif was used as the lead compound. Structure-activity relationship analysis was used to identify stable and potent gelatinase inhibitors suitable for NIR imaging applications.

RESULTS

Replacing the S-S bond in cyclic peptide c(CTTHWGFTLC)NH(2) (C1) with an amide bond between the epsilon-amino group of Lys and the side chain of Asp resulted in a significant increase in stability and a fourfold increase in gelatinase inhibition of the resulting peptide, c(KAHWGFTLD)NH(2) (C6). Conjugation of Cy5.5 to C6 led to Cy5.5-C6, which was selectively taken up by MMP-2 expressing human glioma U87 cells. In vivo, selective accumulation of Cy5.5-C6, but not Cy5.5-C1 or a Cy5.5-scrambled peptide conjugate, was visualized in intratibial prostate PC-3 tumors 48 h after their intravenous injection. Moreover, Cy5.5-C6 was readily visualized in orthotopically inoculated U87 brain tumors.

CONCLUSIONS

Cy5.5-C6 may be a useful agent for molecular imaging of gelatinases. The approach of producing stable cyclic peptides through side chain amide linkage should be applicable to other peptide-based imaging agents.

In situ zymography and immunolabeling in fixed and decalcified craniofacial tissues

In situ zymography is a very important technique that shows the proteolytic activity in sections and allows researchers to observe the specific sites of proteolysis in tissues or cells. It is normally performed in non-fixed frozen sections and is not routinely performed in calcified tissues. In this study, we describe a technique that maintains proteolytic activity in fixed and decalcified sections obtained after routine paraffin sectioning in conventional microtome and cryostat sections. We used adult rat hemimandibles, which presented bone, enamel, and dentine matrices; the substrate used was dye-quenched-gelatin. Gelatinolytic activity was colocalized with MMP-2 using fluorescent antibodies. Specific proteolytic activity was observed in all sections, compatible with metalloproteinase activity, particularly in dentine and bone. Furthermore, matrix metalloproteinase-2 was colocalized to the sites of green fluorescence in dentine. In conclusion, the technique presented here will allow in situ zymography reactions in fixed, decalcified, and paraffin-embedded tissues, and we showed that paraformaldehyde-lysine-periodate-fixed cryostat sections are suitable for colocalization of gelatinolytic activity and protein labeling with antibodies.

Local and systemic responses in matrix metalloproteinase 8-deficient mice during Porphyromonas gingivalis-induced periodontitis

Periodontitis is a bacterium-induced chronic inflammation that destroys tissues that attach teeth to jaw bone. Pathologically excessive matrix metalloproteinase 8 (MMP-8) is among the key players in periodontal destruction by initiating type I collagen degradation. We studied MMP-8 in Porphyromonas gingivalis-induced periodontitis by using MMP-8-deficient (MMP8(-/-)) and wild-type (WT) mice. Alveolar bone loss, inflammatory mediator expression, serum immunoglobulin, and lipoprotein responses were investigated to clarify the role of MMP-8 in periodontitis and systemic inflammatory responses. P. gingivalis infection induced accelerated site-specific alveolar bone loss in both MMP8(-/-) and WT mice relative to uninfected mice. The most extensive bone degradation took place in the P. gingivalis-infected MMP8(-/-) group. Surprisingly, MMP-8 significantly attenuated (P < 0.05) P. gingivalis-induced site-specific alveolar bone loss. Increased alveolar bone loss in P. gingivalis-infected MMP8(-/-) and WT mice was associated with increase in gingival neutrophil elastase production. Serum lipoprotein analysis demonstrated changes in the distribution of high-density lipoprotein (HDL) and very-low-density lipoprotein (VLDL) particles; unlike the WT mice, the MMP8(-/-) mice underwent a shift toward a smaller HDL/VLDL particle sizes. P. gingivalis infection increased the HDL/VLDL particle size in the MMP8(-/-) mice, which is an indicator of lipoprotein responses during systemic inflammation. Serum total lipopolysaccharide activity and the immunoglobulin G-class antibody level in response to P. gingivalis were significantly elevated in both infected mice groups. Thus, MMP-8 appears to act in a protective manner inhibiting the development of bacterium-induced periodontal tissue destruction, possibly through the processing anti-inflammatory cytokines and chemokines. Bacterium-induced periodontitis, especially in MMP8(-/-) mice, is associated with systemic inflammatory and lipoprotein changes that are likely involved in early atherosclerosis.

In situ localization of gelatinolytic activity during development and resorption of Meckel's cartilage in mice

Degradation of Meckel's cartilage in the middle portion is accompanied by hypertrophy and death of chondrocytes, calcification of the cartilaginous matrix, and chondroclastic resorption. We hypothesize that the gelatinolytic activity of matrix metalloproteinases (MMPs) largely contributes to the degradation of extracellular matrix (ECM) in the process. The activity in Meckel's cartilage of mouse mandibular arches at embryonic days 14-16 (E14-E16) was examined by a combination of in situ zymography (ISZ), using quenched fluorescent dye-labeled gelatin as a substrate, with CTT (a selective inhibitor of MMP-2 and -9) or with EDTA (a general MMP inhibitor). On E14 and E15, ISZ showed fluorescence in the perichondrium, in the intercellular septa between chondrocytes, and in the nucleus of chondrocytes. CTT attenuated fluorescence, and EDTA eliminated it. On E16, calcified cartilaginous matrix showed intense fluorescence, and dot-like fluorescence was observed in as-yet uncalcified intercellular septa, even after CTT treatment. EDTA inhibited fluorescence, but unexpectedly intense fluorescence was found in the cytoplasm of hypertrophic chondrocytes facing the resorption front. MMP-2, -9, and -13 immunoreactivity was detected in the perichondrium and chondrocytes of Meckel's cartilage. These findings suggest that MMPs and other proteinases capable of degrading gelatin play an integral role in the development, calcification, and resorption of Meckel's cartilage through ECM reconstitution.

Elevated activities of MMP-2 in the non-tumorous lung tissues of curatively resected stage I NSCLC patients are associated with tumor recurrence and a poor survival

BACKGROUND AND OBJECTIVES

We wanted to assess whether the level of enzyme activity for a particular matrix metalloproteinase (MMP), and not the amount of expressed protein, in lung tissue could be used as a reliable prognostic biomarker for tumor recurrence leading to poorer survival in a certain subgroup of patients who have undergone curative resection for stage I human NSCLC.

METHODS

We determined what type of MMP was significant for tumor recurrence by using a mouse model of pulmonary metastasis with inoculating the footpad with H460 human cancer cells. We then looked for any association between tumor recurrence and the level of enzyme activities for the selected MMP in the tumor and also in the pathologically non-tumorous tissues from 34 stage I lung cancer patients.

RESULTS

We obtained H460/PM6 cells having a highly metastatic potential after six repeated cycles of pulmonary metastasis by using the mouse footpad inoculated with the metastasized cancer cells in the previous cycle. We started with human lung cancer cells, H460, and we found that among the tested MMPs we tested for, the level of MMP-2 mRNA was elevated. No significant difference was seen in the level of enzyme activity of the MMP-2 cells from the curatively resected tumor tissues of the stage I NSCLC patients who were later found with or without recurrence. However, the level of MMP-2 enzyme activity was found to be significantly different between the non-tumorous lung tissues from patients later found with and without recurrence, and it was associated with the 5-year survival rate.

CONCLUSIONS

This observation suggests that the higher level of MMP-2 enzyme activity in the non-tumorous tissues from the patients could be used as a prognostic biomarker to predict post-operative tumor recurrence and survival for patients with stage I NSCLC. The elevated enzyme activity of MMP-2 in the non-tumorous tissue resected from stage I NSCLC could be used as a prognostic indicator for post-operative tumor recurrence and the patients' poor survival. Further, this could be an important aid for physicians' making decision on whether to subject particular patients to post-operative adjunct chemotherapy.

Imaging probes targeting matrix metalloproteinases

During the past few years, several imaging probes targeting matrix metalloproteinases (MMPs) have been developed. Most of these probes have been validated in animal models. Overall, results derived from most of these studies have been disappointing. Whether or not this relates to shortcomings of the imaging probes used or to the set-up of the reported studies is currently unclear. Firstly, MMPs targeted in these studies, MMP-1, -2 and -9, are cell secreted and their expression is known to vary extensively within one tumor type, depending on the stage of development of the tumor and on the presence of naturally occurring TIMPs. Given the lack of data on the levels of MMP expression by incoculated tumor tissue at the time of imaging in most studies reported, it cannot be excluded that the negative results reported are, in fact, false-negative imaging results. Secondly, given that most of the agents used for imaging are intrinsically broad-spectrum agents, their higher affinity for specific subsets of MMPs does not necessarily imply that a positive imaging result also corresponds to overexpression of specific subsets of MMPs, as suggested in some papers published. Accordingly, well-characterized tumor models need to be developed for the purpose of validating currently available, as well as future, MMP-imaging probes. So far, only 111In-DTPA-N-TIMP-2 has been injected in patients, respectively suffering from Kaposi Sarcoma. Imaging results obtained with this agent proved disappointing. Imaging results obtained with other MMP-targeting probes in patients are awaited.

Matrix metalloproteinases, tissue inhibitor of matrix metalloproteinase-1, and laminin-5 gamma2 chain immunolocalization in gingival tissue of endotoxin-induced periodontitis in rats: effects of low-dose doxycycline and alendronate

BACKGROUND

Matrix metalloproteinases (MMPs) play important roles in tissue destruction mechanisms of periodontitis. MMP-8 and -13 are the major collagenases that act in extracellular matrix degradation in periodontal tissues. MMP-14 is a membrane-type MMP, and laminin (Ln)-5 is a basal membrane component. The aim of the present study was to evaluate the effects of doxycycline and alendronate on gingival tissue expression of MMP-8, -13, and -14; tissue inhibitors of MMP (TIMP)-1; and Ln-5 gamma2 chain in experimental periodontitis induced by Escherichia coli endotoxin (LPS) in rats.

METHODS

Experimental periodontitis was induced by repeated injection of LPS. Forty-four adult male Sprague-Dawley rats were divided into five study groups: saline control, LPS, LPS + doxycycline, LPS + alendronate, and LPS + doxycycline + alendronate. Doxycycline and alendronate were given as a single agent or as combination therapy during the 7 days of the experimental study period. On day 7, the rats were sacrificed, and the gingival tissues were analyzed immunohistochemically for expression of MMP-8, -13, and -14, Ln-5 gamma2 chain, and TIMP-1. Alveolar bone loss was evaluated morphometrically under a stereomicroscope. Data were tested statistically by Kruskal-Wallis and Mann-Whitney tests and Spearman correlation analysis.

RESULTS

Alveolar bone loss was significantly higher in the LPS, doxycycline, alendronate, and combination groups than in the saline control group (all P <0.01). MMP-8 expression was significantly higher in the LPS group than in the saline control group (P = 0.001). Individual administration of doxycycline or alendronate significantly decreased the expression of MMP-8 compared to LPS (P = 0.01). Combined drug administration reduced MMP-14 significantly compared to doxycycline (P = 0.004). No significant differences in Ln-5 gamma2 chain expression were found between the study groups (P >0.05). MMP-14 significantly correlated with the Ln-5 gamma2 chain in the LPS + alendronate group (P = 0.04) and with the amount of alveolar bone loss in the LPS + doxycycline + alendronate group (P = 0.03).

CONCLUSIONS

Our findings suggest that alendronate and/or doxycycline may inhibit MMP-8 expression significantly; particularly, their combined administration may provide beneficial effects in periodontal treatment. Moreover, individual administration of alendronate and doxycycline results in significant increases in TIMP-1 expression in gingiva. However, these effects of combined low-dose doxycycline and alendronate on MMPs and TIMP should be verified by clinical human trials before these agents are used in dental practice.

Gingival crevicular fluid laminin-5 gamma2-chain levels in periodontal disease

AIM

Our study aimed to examine the molecular forms and gingival crevicular fluid (GCF) levels of laminin-5 gamma2-chain in patients with different periodontal disease, and compare the effects of P.gingivalis trypsin-like proteinase on intact laminin-5 gamma2-chain species.

METHODS

Eighteen patients with generalized aggressive periodontitis (G-AgP), 29 patients with chronic periodontitis (CP), 20 with gingivitis and 20 periodontally healthy subjects were included. Probing depth, clinical attachment loss, presence of bleeding on probing and plaque were recorded. Molecular forms and GCF laminin-5 gamma2-chain levels and the effects of P. gingivalis trypsin-like proteinase on intact laminin-5 gamma2-chain were analysed by computer-quantitated Western immunoblotting.

RESULTS

Laminin-5 gamma2-chain 40 and 70 kDa fragments could be detected in all groups, in varying levels. The CP group had elevated GCF laminin-5 gamma2-chain fragment levels compared with the gingivitis and healthy groups (p<0.008). The G-AgP group had GCF laminin-5 gamma2-chain fragment levels similar to the gingivitis and healthy groups (p>0.008). GCF laminin-5 gamma2-chain fragments differed clearly from the multiple lower molecular size fragments of P.gingivalis trypsin-laminin-5 gamma2-chain proteinases.

CONCLUSION

Increased GCF laminin-5 gamma2-chain fragments in periodontitis sites with deep periodontal pocket suggest that these cleaved 40 and 70 kDa fragments could reflect the extent of the inflammatory reaction in CP.

The MMP activity in developing rat molar roots and incisors demonstrated by in situ zymography

Matrix metalloproteinases (MMPs) have been expressed during root development and periodontal tissue formation, whereas it is not known if these MMP molecules are enzymatically active to degrade the extracellular matrices (ECMs). The present study was designed to investigate the gelatinolytic and collagenolytic activity in rat molar root and incisor development. Three-week old rat mandibles were frozen and cut without fixation or decalcification and processed for in situ zymography using substrates gelatin and collagen. The enzymatic activity was assessed according to the intensity of fluorescence due to the lysis of the substrates. Odontoblasts, predentin, cementum, bone and the enamel matrix showed the high activity. The present study demonstrated MMP activity in calcified tissues using in situ zymography for the first time and the possible involvement of the MMP activity in molar root and incisor development and periodontal tissue formation.

Human tongue carcinoma growth is inhibited by selective antigelatinolytic peptides

Matrix metalloproteinases (MMP-2 and MMP-9, or gelatinases) are involved in tongue SCC invasion, metastasis and angiogenesis. We have recently shown that a novel and selective hydrophobic cyclic CTTHWGFTLC (CTT1) peptide is inhibitor for MMP-2 and MMP-9 (Koivunen et al., Nat Biotechnol 1999; 17:768-74). In this study, we demonstrate that both the new hydrophilic derivate GRENYHGCTTHWGFTLC (CTT2) peptide and the CTT1 peptide inhibited specifically the human tongue squamous cell carcinoma (HSC-3) cell-derived gelatinolytic activity and in vitro invasion and migration of these cells (p < or = 0.049). In situ zymography revealed that both peptides also inhibited clearly almost all of the gelatinolytic activity present in the human tongue SCC tissue sections, indicating that MMP-2 and MMP-9 are the major gelatinases detected in the tongue carcinomas. However, CTT2 did not inhibit the type I collagen degradation by human collagenases (MMP-1, MMP-8 and MMP-13). Furthermore, CTT2 reduced the blood vessel density (p < or = 0.043) and clearly improved the survival of the mice bearing human tongue carcinoma xenografts (p < or = 0.012). Overall, we suggest that CTT1 and CTT2 peptides being selective gelatinase inhibitors with significant anti-tumor properties could be useful to diminish the invasion and angiogenesis of human tongue carcinomas characterized by enhanced gelatinolytic activity in tumors.

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.

Effectiveness of Adjunctive Low-Dose Doxycycline Therapy on Clinical Parameters and Gingival Crevicular Fluid Laminin-5 γ2 Chain Levels in Chronic Periodontitis

BACKGROUND

Laminin-5 (Ln-5) is involved in the apical migration of epithelial cells during the development of periodontal pockets. Low-dose doxycycline (LDD) can therapeutically modulate the host response with its non-antimicrobial properties. In the present randomized, double-blind, placebo-controlled, parallel arm study, the effectiveness of LDD in combination with non-surgical periodontal therapy on gingival crevicular fluid (GCF) Ln-5 gamma2 chain fragment levels and clinical parameters in patients with chronic periodontitis was examined over a 12-month period.

METHODS

GCF samples were collected and clinical parameters including probing depth (PD), clinical attachment level, gingival index (GI), and plaque index were recorded. Thirty chronic periodontitis patients were randomized either to low-dose doxcycline or placebo groups. LDD group received doxycycline (20 mg, b.i.d.) for 3 months plus scaling and root planing (SRP), while placebo group was given placebo capsules b.i.d. for 3 months plus SRP. The patients were evaluated every 3 months during the 12-month study period. All clinical parameters and GCF sampling were repeated at each visit. GCF Ln-5 gamma2 chain fragment levels were determined by Western immunoblotting using specific antibody and quantitated by computerized image analysis. Friedman test was used for intragroup comparisons followed by Wilcoxon signed rank test to analyze significance of changes over time. The Mann-Whitney test was used to determine differences between both LDD and placebo groups.

RESULTS

Both groups revealed significant improvements in all clinical parameters over the 12-month period (P < 0.0125). LDD group showed a significantly greater reduction in the mean PD scores at 9 and 12 months and in the mean GI scores at all time points than the placebo group (P < 0.05). In the LDD group, GCF Ln-5 gamma2 chain fragment levels were significantly reduced at 3 months (P < 0.0125) and then slightly increased during the rest of the study period. In the placebo group, GCF 45 and 70 kDa Ln-5 gamma2 chain fragments tended to decrease at 3 months compared to baseline, but did not reach significance; these levels continued to increase throughout the remainder of the study period. GCF Ln-5 gamma2 chain fragment levels in LDD group were significantly lower than those of the placebo group during the study period (P < 0.05).

CONCLUSIONS

The present data indicate that LDD therapy in combination with SRP therapy can reduce GCF Ln-5 gamma2 chain fragment levels and improve clinical periodontal parameters in patients with chronic periodontitis. Since matrix metalloproteinases (MMP)-mediated fragmentation of laminin-5 can contribute to pocket formation by stimulating epithelial cell migration, the reduction of Ln-5 gamma2 chain fragment levels could provide a new mechanism by which LDD, adjunctive to SRP, inhibits periodontal disease more effectively than SRP alone. Thus, these results provide extended and additional information about the effectiveness of the LDD therapy as an adjunct to non-surgical periodontal therapy in the long-term management of periodontal disease.

Emerging role of relaxin in renal and cardiovascular function

Although traditionally associated with reproductive processes, relaxin is emerging as an important player in renal and cardiovascular function. Much of our recently acquired understanding of relaxin in this new context has arisen from studies of maternal renal and cardiovascular adaptations to pregnancy in rats where the hormone is turning out to be an important mediator. First, we highlight the influence of relaxin on renal hemodynamics and glomerular filtration rate, as well as on other peripheral circulations. Second, we discuss the effect of relaxin on both the steady and pulsatile systemic arterial load, as well as on the heart, in particular, coronary blood flow. Third, we consider the impact of the hormone on cultured endothelial and vascular smooth muscle cells. Fourth, we address the interaction of relaxin with renal and cardiac disease, as well as its role in angiogenesis. Finally, in Perspectives, we point out several key research questions in need of investigation that relate to a potential autocrine/paracrine role of relaxin in renal and cardiovascular tissues. Furthermore, on the basis of its potent vasodilatory and matrix-degrading attributes, we speculate about the therapeutic potential of relaxin in renal and cardiovascular diseases.

Metabolic mapping of proteinase activity with emphasis on in situ zymography of gelatinases: review and protocols

Proteases are essential for protein catabolism, regulation of a wide range of biological processes, and in the pathogenesis of many diseases. Several techniques are available to localize activity of proteases in tissue sections or cell preparations. For localization of the activity of matrix metalloproteinases, in situ zymography was introduced some decades ago. The procedure is based on zymography using SDS polyacrylamide gels containing gelatin, casein, or fibrin as substrate. For in situ zymography, either a photographic emulsion containing gelatin or a fluorescence-labeled proteinaceous macromolecular substrate is brought into contact with a tissue section or cell preparation. After incubation, enzymatic activity is revealed as white spots in a dark background or as black spots in a fluorescent background. However, this approach does not allow precise localization of proteinase activity because of limited sensitivity. A major improvement in sensitivity was achieved with the introduction of dye-quenched (DQ-)gelatin, which is gelatin that is heavily labeled with FITC molecules so that its fluorescence is quenched. After cleavage of DQ-gelatin by gelatinolytic activity, fluorescent peptides are produced that are visible against a weakly fluorescent background. The incubation with DQ-gelatin can be combined with simultaneous immunohistochemical detection of a protein on the same section. To draw valid conclusions from the findings with in situ zymography, specific inhibitors need to be used and the technique has to be combined with immunohistochemistry and zymography. In that case, in situ zymography provides data that extend our understanding of the role of specific proteinases in various physiological and pathological conditions.

Cross-talk between RhoGTPases and stress activated kinases for matrix metalloproteinase-9 induction in response to keratinocytes injury

Cell migration and extracellular matrix remodeling are two essential processes of wound healing, regulated by extracellular metalloproteinases such as matrix metalloproteinase-2 (Gelatinase A) and matrix metalloproteinase-9 (Gelatinase B). Expression of matrix metalloproteinase-9 is deregulated in numerous wound healing pathologies. To date the mechanisms regulating matrix metalloproteinase-9 during normal wound healing are poorly documented. Using both primary cultures of normal human keratinocytes and a wounding device especially designed to dissect the molecular events during the healing process in vitro, we show that matrix metalloproteinase-9 is stimulated by injury in normal human keratinocytes. This upregulation results from the mechanical stress created by injury and not from a soluble factor, secreted by wounded normal human keratinocytes. We also demonstrate that the Rho family of small GTPases, p38[MAPK] and JNK together play a key part in the signaling pathways controlling the stimulation of matrix metalloproteinase-9 in wounded cells. We provide lines of evidence indicating that in wounded keratinocytes, upregulation of matrix metalloproteinase-9 depends on two distinct pathways. The first involves Rac1 and/or Cdc42 that control the activation of p38[MAPK]. The second depends on RhoA activation that is required for stimulation of JNK.

Essential role for vascular gelatinase activity in relaxin-induced renal vasodilation, hyperfiltration, and reduced myogenic reactivity of small arteries

During pregnancy, relaxin stimulates nitric oxide (NO)-dependent renal vasodilation, hyperfiltration and reduced myogenic reactivity of small renal arteries via the endothelial ETB receptor subtype. Our objective in this study was to elucidate the mechanisms by which relaxin stimulates the endothelial ETB receptor/NO vasodilatory pathway. Using chronically instrumented conscious rats, we demonstrated that a specific peptide inhibitor of the gelatinases MMP-2 and -9, cyclic CTTHWGFTLC (cyclic CTT), but not the control peptide, STTHWGFTLS (STT), completely reversed renal vasodilation and hyperfiltration in relaxin-treated rats. Comparable findings were observed with a structurally different and well-established, general antagonist of MMPs, GM6001. In contrast, phosphoramidon, an inhibitor of endothelin-converting enzyme, did not significantly change the renal vasodilatory response to relaxin administration. When small renal arteries were incubated with either of the general MMP inhibitors, GM6001 or TIMP-2 (tissue inhibitor of MMP), or with the specific gelatinase inhibitor, cyclic CTT, the reduced myogenic reactivity of these blood vessels from relaxin-treated nonpregnant and midterm pregnant rats was totally abolished. Moreover, a neutralizing antibody specific for MMP-2 completely abrogated the reduced myogenic reactivity of small renal arteries from relaxin-treated nonpregnant and midterm pregnant rats. In contrast, phosphoramidon did not significantly affect the reduction in myogenic reactivity. Using gelatin zymography, we showed increased pro and active MMP-2 activity in small renal arteries from relaxin-treated nonpregnant and midterm pregnant rats relative to the control animals. Thus, inhibitors of MMPs in general and of gelatinases in particular reverse the renal vascular changes induced by pregnancy or relaxin administration to nonpregnant rats. Finally, the typical reduction in myogenic reactivity of small renal arteries from relaxin-treated nonpregnant rats was absent in ETB receptor-deficient rats, despite an increase in vascular MMP-2 activity. These results indicate an essential role for vascular gelatinase, which is in series with, and upstream of, the endothelial ETB receptor/NO signaling pathway in the renal vasodilatory response to relaxin and pregnancy.

Matrix metalloproteinases process the laminin-5 gamma 2-chain and regulate epithelial cell migration

Matrix metalloproteinase (MMP)-2 and membrane type 1-MMP can process the laminin-5 (Ln-5) gamma2-chain, revealing a cryptic site inducing epithelial cell migration. We investigated whether other MMPs process the Ln-5 gamma2-chain and related their ability to induce epithelial cell migration. The N-terminal sequences of the MMP-3, -12, -13, and -20 processed 80kDa Ln-5 gamma2x-chains were identical whereas the N-terminus of the 80kDa(MMP-8) Ln-5 gamma2x-chain was not. MMP-3, -13, -14, and -20 induced MCF-7 cell migration over Ln-5 while MMP-8 was a poor inducer of MCF-7 cell migration. In conclusion, several MMPs can process the Ln-5 gamma2-chain and induce epithelial cell migration.

Laminin-5 gamma2-chain and collagenase-2 (MMP-8) in human peri-implant sulcular fluid

Laminin-5 (LN-5) is an important epithelial cell-derived structural and adhesive component in hemidesmosomes and basement membranes (BM). In peri-implant tissue, gingival BM underlies the junctional epithelium (JE) and reflects the peri-implant health. Matrix metalloproteinase-8 (MMP-8 or collagenase-2) is one of the key mediators of periodontal tissue destruction. Western immunoblotting with image analysis was used to quantitate the molecular forms of LN-5 gamma2-chain and MMP-8 in peri-implant sulcular fluid (PISF) from healthy and diseased implants. These observations were related to the recorded gingival (GI) and bone resorption (BR) indices of the studied sites. Altogether, 72 PISF samples from osseointegrated dental implants were examined. Significantly elevated levels of fragmented LN-5 gamma2-chain species (45 and 70 kDa) and MMP-8 immunoreactivities were observed in diseased PISF in relation to healthy PISF. The elevated levels of both LN-5 gamma2-chain 45 and 70 kDa fragments and MMP-8 in diseased PISF from peri-mucositis (BR = 0) and peri-implantitis (BR >/= 1) lesions strongly correlated with elevated GI. Low levels - almost comparable to those seen in healthy control PISF - were seen in PISF from peri-implantitis lesions (BR >/= 1) with no GI. Activation of 75 kDa neutrophil (PMN)-type proMMP-8 to 10 kDa lower-molecular-size active forms was especially detected in PISF from peri-implantitis with elevated GI. These cross-sectional findings indicate that elevated MMP-8 and LN-5 gamma2-chain fragment levels in PISF can reflect the active phase of the inflammatory peri-implant disease. Longitudinal studies are required to assess their use, either alone or in combination as molecular biochemical PISF markers, to predict the risk of progression of peri-implantitis, as well as to monitor the impact of treatment of the disease.

Laminin-5 gamma 2 chain is colocalized with gelatinase-A (MMP-2) and collagenase-3 (MMP-13) in odontogenic keratocysts

BACKGROUND

Odontogenic keratocyst (KC) differs from other epithelial odontogenic cysts in regard to increased epithelial proliferation and a strong tendency to recur. Laminin-5 (Ln-5) is an epithelial anchoring filament component, which after modulation by certain matrix metalloproteinases (MMPs), like MMP-2 and MMP-13, induces epithelial cell migration.

METHODS

Using in situ hybridization and immunohistochemistry, we studied the Ln-5 gamma-2 chain expression related to the expression of MMP-2, -8, and -13 in different odontogenic cysts, including radicular cysts (RC; n = 11), follicular cysts (FC; n = 11), and odontogenic keratocysts (KC; n = 16).

RESULTS

Ln-5 mRNA was present in all cysts examined, while less than half of KCs and RCs (33 and 40%, respectively) demonstrated MMP-2 mRNA. MMP-13 mRNA was present in all KC samples. Ln-5 protein was located as a continuous ribbon in BM zone of all KCs, and MMP-2 and MMP-13 immunoreactivities colocated significantly with Ln-5 in that area. MMP-8 was expressed by stromal macrophages and epithelial goblet cells, but never located in BM zone.

CONCLUSIONS

Our results indicate that the colocalization of Ln-5 with MMP-2 or MMP-13, but not with MMP-8, in BM zone of KCs, may be related to special characteristics of KC.

Matrix metalloproteinase-9 in lung remodeling

Matrix metalloproteinase (MMP)-9 (Gelatinase B, 92-kD type IV collagenase, EC 3.4.24.35) is an MMP that is present in low quantities in the healthy adult lung, but much more abundant in several lung diseases, including asthma, idiopathic pulmonary fibrosis (IPF), and chronic obstructive pulmonary disease (COPD). Despite numerous reports of MMP-9 in these and other lung diseases, whether MMP-9 is causal in lung remodeling or part of the inflammatory and reparative response remains to be determined. Many intrinsic lung cells can be stimulated to produce MMP-9, but much of the information regarding MMP-9 in the lung deals with MMP-9 from inflammatory cells. The multiple locations and cell types producing MMP-9 are consistent with multiple functions in different microenvironments. In addition to digestion of structural proteins and antiproteases, MMP-9 can modify cellular function by regulation of cytokines and matrix-bound growth factors. Determining the role of MMP-9 in health and disease will be important, because broad spectrum and specific inhibitors will soon be available to enable conversion of the bench knowledge to bedside practice. This review addresses the current understanding of MMP-9 in human asthma, IPF, and COPD, and in animal models of these conditions.

Chemically modified tetracycline (CMT-8) and estrogen promote wound healing in ovariectomized rats: effects on matrix metalloproteinase-2, membrane type 1 matrix metalloproteinase, and laminin-5 gamma2-chain

Estrogen deficiency is associated with impaired cutaneous wound healing. Remodeling of the extracellular matrix in wound healing involves the action of matrix metalloproteinases on basement membrane zone components, especially laminin-5. We studied the effects of estrogen and a potent matrix metalloproteinase inhibitor, chemically modified non-antimicrobial tetracycline, CMT-8, on wound healing in ovariectomized rats. At the tissue level, laminin-5 gamma2-chain expression was decreased and the migration-inductive 80 kDa form of laminin-5 gamma2-chain was absent in ovariectomized rats when compared with sham and CMT-8- or estrogen-treated ovariectomized animals as detected by Western blotting. The highest levels of gelatinolytic activity (matrix metalloproteinase-2 and -9) were found in sham animals. Levels were reduced in ovariectomized rats and were lowest after treating ovariectomized rats with CMT-8 or estrogen as analyzed by functional activity assay and zymography. The total amount of membrane type 1-matrix metalloproteinase was unchanged in all groups. We conclude that CMT-8 and estrogen can promote wound healing in ovariectomized rats, not only by normalizing wound bed total collagen content and structure, but also by recovering the expression and processing of key molecules in wound healing, i.e., laminin-5 gamma2-chain. This study shows, for the first time, the role of estrogen and CMT-8 in laminin-5 gamma2-chain modulation in vivo.