Matrix metalloproteinase (MMP)-9 type IV collagenase/gelatinase implicated in the pathogenesis of Sjögren's syndrome.

Type IV collagenases/gelatinases (matrix metalloproteinases MMP-2 and MMP-9) in labial salivary glands (LSG) and saliva in Sjögren's syndrome (SS) and healthy controls were studied. Zymograms and Western blots disclosed that SS saliva contained 92/82 kD MMP-9/type IV collagenase duplex. Specific activity measurement disclosed 53.1+/-9.8 U/mg protein MMP-9 in SS compared to 16.5+/-2.6 U/mg in healthy controls (p=0.01). MMP-2 did not differ between SS and controls. In SS salivary glands, MMP-2 and MMP-9 were also expressed, in addition to stromal fibroblasts and occasional infiltrating neutrophils, respectively, in acinar end piece cells. In addition, an effective proMMP-9 activator, human trypsin-2 (also known as tumor-associated trypsin-2 or TAT-2), was found in acinar end piece cells and in saliva. Interestingly, proteolytically processed MMP-9 was found in saliva (vide supra), and in vivo activated MMP-9 was significantly higher in SS than in controls (p=0.002). LSGs, particularly in SS, were characterized ultrastructurally by areas containing small cytoplasmic vesicles in the basal parts of the epithelial cells associated with areas of disordered and thickened basal lamina. Based on our results, we conclude here that SS saliva contains increased concentrations of MMP-9, which is of glandular origin in part. Pro MMP-9 is to a large extent proteolytically activated. This is probably mediated by the most potent pro MMP-9 activator found in vivo thus far, namely trypsin-2. Therefore, the MMP 9/trypsin-2 cascade may be responsible for the increased remodelling and/or structural destruction of the basement membrane scaffolding in salivary glands in SS. Due to the role of basal lamina as an important molecular sieve and extracellular matrix-cell signal, these pathological changes may contribute to the pathogenesis of the syndrome.

Salivary mucous glycoprotein MG1 in Sjögren's syndrome.

The aim of the study was to develop and apply a rapid method for the simultaneous analysis of the concentration and molecular weight of the human high-molecular weight mucin MG1 in small volumes of unprocessed saliva from healthy controls and from patients with Sjögren's syndrome (SS). In high performance liquid chromatography (HPLC) with a TSK 5000 PW size exclusion column, MG1 eluted with a retention time 10.6 min corresponding to a M(r) of 2 to 2.5 x 10(6). Molecular weight changes under various experimental conditions are compatible with the suggestion that the MG1 complex is composed of four 660 x 10(3) glycosylated subunits connected by disulphide bridges and associated with a 25-35 x 10(3) Da link protein. In SS the molecular weight of MG1 was normal and its concentration was high in resting (190 vs. 70 micrograms/ml, P = 0.001) but not in stimulated (46 vs. 48 micrograms/ml, P > 0.05) saliva; MG1 concentration in resting SS saliva did not vary in parallel with protein and the interindividual differences were considerable. Size exclusion HPLC is a rapid and reproducible method suitable for isolation and analysis of salivary MG1 from small volumes of unprocessed samples. The molecular weight or subunit structure of MG1 were not altered in SS. The high concentration of MG1 in resting saliva in SS, may be explained by the concentration effect, or alternatively by the low water retaining capacity, which may play an important pathogenic role in xerostomia of SS.

Characterization of matrix metalloproteinase (MMP-8 and -9) activities in the saliva and in gingival crevicular fluid of children with Down's syndrome.

Previous studies have shown increased susceptibility to periodontal diseases in children with Down's syndrome (DS). The mechanisms involved in the periodontal inflammatory processes in DS are not fully understood. The present study characterized the periodontal status of 9 non-institutionalized DS children 9 to 17 years old (mean 13.6 years) relative to their age-matched systemically and periodontally healthy controls. The periodontal status was assessed by visible plaque index (VPI), gingival bleeding index (GBI), and probing depth. We also assessed, by sodium dodecyl sulphate polyacrylamide gel electrophoresis/laser densitometry and by zymography, the collagenase and gelatinase activities in the gingival crevicular fluid (GCF) and saliva samples collected from DS patients and from the controls. Eight of the nine DS children showed a periodontium comparable to that seen in healthy controls; beginning alveolar bone loss was radiographically seen in the DS patient with deep periodontal pockets. The endogenously active collagenase and total collagenase activities were slightly higher in GCF of DS children compared to healthy controls. Western blot demonstrated that GCF collagenase of DS patients was human neutrophil collagenase (MMP-8 or collagenase-2), which occurred in 75 kDa proMMP-8 and in DS patients, but not in controls, also in 65 kDa active MMP-8 form and occasionally lower 40-50 kDa MMP-8 species. Zymographic analysis revealed the presence of 120 kDa (MMP-9 complexed with neutrophil gelatinase associated lipocalin or NGAL), 92 kDa (MMP-9) and 72 kDa (MMP-2) gelatinases in DS and control GCF. Especially in DS GCF MMP-9 occurred in part in 82-85 kDa activated form. Salivary collagenase in DS was high when compared to controls but of the same MMP-8 type as in control saliva. Our findings suggest that in vivo activated MMP-8 in GCF derived from triggered PMNs and/or cytokine-induced periodontal fibroblasts may reflect periodontal tissue and alveolar bone destruction seen in the early stages of gingivitis/periodontitis associated with Down's syndrome.

Tetracycline inhibition and the cellular source of collagenase in gingival crevicular fluid in different periodontal diseases. A review article.

Tetracyclines have recently been shown to inhibit the activity of some but not all mammalian matrix metalloproteinases believed to mediate periodontal destruction. However, the specificity of this effect, which could have significant therapeutic implications for different periodontal diseases, has not been examined in detail. Doxycycline and 4-de-dimethylaminotetracycline (CMT-1) have been tested in vitro for their ability to inhibit human neutrophil and fibroblast interstitial collagenases and collagenase in human gingival crevicular fluid (GCF). The GCF samples were obtained from systemically healthy and insulin-dependent diabetic adult periodontitis patients and from localized juvenile periodontitis (LJP) patients. The concentrations of these 2 tetracyclines required to inhibit 50% of the collagenase activity (IC50) were found to be 15 to 30 microM for human neutrophil collagenase and for collagenase in GCF of systemically healthy and diabetic adult periodontitis patients. These concentrations approximate the tetracycline levels observed in vivo during treatment with these drugs. In contrast, human fibroblast collagenase and GCF collagenase from LJP patients were both relatively resistant to tetracycline inhibition; the IC50 for doxycycline and CMT-1 for these 2 sources of collagenase were 280 and 500 microM, respectively. Based on these and other findings, we propose the following: 1) that systemic levels of tetracycline may inhibit connective tissue breakdown by inhibiting neutrophil collagenase; 2) that tetracyclines do not inhibit fibroblast-type collagenase, which may help explain their lack of effect on normal connective tissue remodeling; 3) that tetracycline inhibition of collagenases may serve to identify the cellular origin of the enzyme; and 4) that tetracyclines can also prevent the oxidative activation of latent human procollagenases.(ABSTRACT TRUNCATED AT 250 WORDS)

Tetracycline inhibition identifies the cellular sources of collagenase in gingival crevicular fluid in different forms of periodontal diseases.

Tetracyclines have recently been shown to inhibit the activity of mammalian matrix metalloproteinases, i.e. type I collagenase (MMP-1) and type IV collagenase/gelatinase (MMP-2). The specificity of this effect, however, has not been examined in detail. In the present study, doxycycline (a clinically widely used commercial tetracycline) and 4-de-dimethylaminotetracycline (CMT-1, a chemically modified non-antimicrobial tetracycline) were tested, at a wide range of concentrations, for their ability to inhibit human neutrophil and fibroblast interstitial collagenases, which are distinct gene products, as well as collagenase in human gingival crevicular fluid (an inflammatory exudate in periodontal lesions) obtained from adult, juvenile and diabetic adult periodontitis patients. The concentrations of these two tetracyclines, required to inhibit 50% of the collagenase activity (IC50), were found to be 15-30 microM for purified human neutrophil collagenase as well as collagenase in gingival crevicular fluid of adult periodontitis patients and diabetic adult periodontitis patients, thus approximating in vivo therapeutic tetracycline levels. In contrast, the fibroblast collagenase and collagenase in gingival crevicular fluid of patients with juvenile periodontitis were relatively resistant to tetracycline inhibition: the IC50 for doxycycline and CMT-1 were 280 and 500 microM, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Reactive oxygen species as regulators of human neutrophil and fibroblast interstitial collagenases.

The effects of various reactive oxygen species on latent human neutrophil and fibroblast-type interstitial collagenases were studied. Latent human neutrophil collagenases (proMMP-8) was efficiently activated by hypochlorous acid and hydrogen peroxide and less efficiently by the serine proteinases trypsin and chymotrypsin. Human plasmin and plasma kallikrein did not activate latent human neutrophil collagenase. The activation of latent human neutrophil collagenase by hypochlorous acid and hydrogen peroxide corresponded to the activation obtained with the other known non-proteolytic activators phenylmercuric chloride and gold thioglucose. The activation by hydrogen peroxide was inhibited by mannitol and desferoxamine, suggesting a localized Fenton-type reaction to be responsible for the generation of hydroxyl radical and/or hydroxyl radical-like reactive oxygen pathway of neutrophil procollagenase does not involve plasmin and plasma kallikrein, which are efficient proteolytic activators of latent fibroblast-type procollagenase (proMMP-1). Fibroblast procollagenase was also slightly activated by hypochlorous acid and gold thioglucose. Thus neutrophil procollagenase seems to prefer non-proteolytic means of activation and reactive oxygen species can be regarded as potent activators in vivo. Synovial-fluid neutrophils from rheumatoid arthritis patients were found to release collagenase in 30% active form when compared to same patients' peripheral blood neutrophils, which released collagenase in completely latent form. This may indicate that the triggering of neutrophil at the site of inflammation in vivo involves initial oxidative activation of collagenase upon the degranulation process.

Doxycycline protects serum alpha-1-antitrypsin from human neutrophil collagenase.

Interstitial collagenases, members of the matrix metalloproteinase family, are key initiators of collagen destruction during various disorders such as rheumatoid arthritis. Recently interstitial collagenases were found to efficiently degrade an additional non-collagenous substrate, the serum alpha-1-antitrypsin (AAT also called alpha-1-proteinase inhibitor or serpin). Serpins are major endogenous inhibitors of serine proteinases, particularly neutrophil elastase. Of relevance to neutrophil-mediated collagen degradation, the tetracycline family of antibiotics are now known to inhibit inhibit mammalian collagenases by a mechanism unrelated to their antimicrobial activity. This study identifies an additional mechanism by which tetracyclines may retard tissue breakdown during inflammatory diseases. Doxycycline, added to the reaction mixture as in concentrations as low as 10 microM, which correspond to levels of the drug readily achieved in vivo, produced detectable inhibition of serpinase activity of neutrophil collagenase, although levels of 50-100 microM or greater were required to reduce AAT degradation more than 75%. The concentration of doxycycline to inhibit 50% (IC50 of serpinase activity) of AAT degradation by neutrophil collagenase was found to approximate 20 microM, a value similar to the IC50 for doxycycline required to inhibit collagen degradation by neutrophil collagenase. Doxycycline was also found to inhibit at cell level neutrophil-mediated degradation of AAT. The protection of bodies' AAT-shield from serpinolytic activity of collagenase would result in inhibition of serine proteinases such as neutrophil elastase. Tetracyclines may thus protect matrix constituents from a wider spectrum of neutral proteases than previously recognized, not just from the matrix metalloproteinases collagenase and gelatinase.

Doxycycline in the protection of serum alpha-1-antitrypsin from human neutrophil collagenase and gelatinase.

The concentration of doxycycline required to inhibit 50% (50% inhibitory concentration for serpinase activity) of alpha-1-antitrypsin degradation by purified neutrophil collagenase was found to be approximately 20 microM, a value similar to the 50% inhibitory concentration of doxycycline required to inhibit collagen degradation by neutrophil collagenase. Doxycycline also efficiently inhibited phorbol myristate acetate-triggered neutrophil-mediated degradation of alpha-1-antitrypsin. This suggests that doxycycline can protect alpha-1-antitrypsin from collagenase and gelatinase in the presence of other proteases and biologically active molecules that are released by triggered neutrophils. The protection of a body's alpha-1-antitrypsin shield from serpinolytic activity of collagenase and matrix metallproteinases can result in inhibition of serine proteases such as neutrophil elastase. Tetracyclines may thus protect matrix constituents from a wider spectrum of neutral proteases than previously recognized, not just from the matrix metalloproteinases collagenase and gelatinase.

Cellular source and tetracycline-inhibition of gingival crevicular fluid collagenase of patients with labile diabetes mellitus.

Accelerated periodontal tissue destruction in patients with labile insulin-dependent diabetes mellitus (DM) and localized juvenile periodontitis (LJP) has been suggested to be related to functional abnormalities of neutrophils. We have recently found that collagenase in gingival crevicular fluid (GCF) of adult periodontitis patients is primarily derived from neutrophils and that neutrophil collagenase activity is more sensitive to inhibition by tetracyclines than collagenase produced by fibroblasts. This study is to characterize the cellular sources, activation and inhibition of collagenase in GCF of DM patients and to compare it with collagenase in LJP GCF. We found differences which may have therapeutic implications. Specific doxycycline inhibition tests revealed that GCF collagenase in DM is derived from neutrophils, whereas the enzyme in LJP originates primarily from fibroblasts. Oxidant, sodium hypochlorite, activated efficiently GCF collagenase of DM but not LJP patients. In contrast, plasmin activated LJP GCF collagenase but not that of DM patients. In GCF of DM patients 50-60% of collagenase existed in an active form, whereas in LJP GCF, the enzyme was almost completely in a latent form. The results suggest that collagenase in GCF of periodontitis patients with labile DM is primarily derived from neutrophils and that tetracycline therapy may be an effective adjunct in treatment aimed at controlling the periodontal breakdown in these patients. On the other hand, in LJP the anti-collagenase property of tetracyclines may be less important for control of periodontal tissue destruction because of the tetracycline-resistance of fibroblast collagenase.