The microenvironment around total hip replacement prostheses.

The metal stem of the totally replaced hip carries load and resists fatigue, but it is electrochemically corroded. Metallic atoms act as haptens, induce type 1 T-helper cells/Th1-type immune responses and enhance periprosthetic osteolysis. Stiff metal implants, which do not have the same elasticity as the surrounding bone, cause stress shielding. Cyclic loading and lack of ligamentous support lead to mechanical and ischemia reperfusion injury and particle formation from bone, polymethylmethacrylate, and porous implant surfaces, which accelerate third-body polyethylene wear. Surgical injury and micromotion induce the formation of a fibrous capsule interface. Type-B lining cells produce lubricin and surface-active phospholipids to promote solid-to-solid lubrication but may loosen the implant from bone. The pumping action of the cyclically loaded joint and synovial fluid pressure waves dissect the implant-host interface and transports polyethylene particles and pro-inflammatory mediators to the interface. Hyaluronan induces formation of a synovial lining like layer. Because of its localization close to bone, foreign body inflammation at the interface stimulates osteoclastogenesis and peri-implant bone loss. Metal-on-metal and ceramic-on-ceramic pairs might minimize third body wear, but can lead to high-impact load of the acetabulum. Diamond coating of a metal-on-polyethylene couple might solve both of these problems. The basic biomaterial solutions allow good mechanical performance and relatively long life in-service, but surface modifications (porous coating, hydroxyapatite, diamond, bioglass, and others) may facilitate performance of the implant and improve the biomaterial and body interfaces.

Levels and molecular forms of MMP-7 (matrilysin-1) and MMP-8 (collagenase-2) in diseased human peri-implant sulcular fluid.

OBJECTIVES: Matrix metalloproteinases (MMPs) play crucial role in various tissue destructive inflammatory processes by degrading almost all peri-cellular and basement membrane components. MMP-8 (collagenase-2) is the major MMP in periodontitis. MMP-7 (matrilysin-1), in addition to its ability to degrade matrix and basement membrane components, activates other latent pro-MMPs and defensins, host cell-derived antimicrobial cryptidins. The aim of the present study was to characterize the relationship, levels and molecular forms of MMP-8 and MMP-7 in diseased peri-implant sulcular fluid (PISF). MATERIALS AND METHODS: Seventy-two human dental implant fluid samples were collected with filter paper strips from peri-implant sulci from healthy and untreated diseased implant sites. Gingival index (GI) and/or bone resorption (BR) were also recorded. Western immunoblot method with polyclonal anti-human-MMP-8 and monoclonal anti-human-MMP-7 antibodies was used, and immunoreactivities were quantified with computer scanning program. The effects of MMP inhibitors (doxycycline, chemically modified tetracycline-3, clodronate, CTT-peptide and marimastat) were studied on the activity of recombinant human matrilysin-1 (MMP-7) using beta-casein degradation assay. RESULTS: The levels of active forms of MMP-8 and MMP-7 were significantly elevated in diseased PISF in relation to healthy PISF. Furthermore, MMP-8 and MMP-7 levels correlated significantly to each other and GI. MMP-8 was present not only as bands corresponding to 75-kDa polymorphonuclear leukocyte (PMN) -type pro- and 65-kDa active forms, but also as 55-kDa non-PMN-type pro- and 45-kDa active forms. Immunoreactivities > 80 kDa most likely represented dimeric and/or inhibitor-bound MMP-8 complexes and the low molecular weight (< 30 kDa) species were apparently degraded fragments. In diseased PISF, 19-21-kDa active MMP-7 and 28-30-kDa pro-MMP-7 species were detected, and the active 19-21-kDa forms of MMP-7 predominated in diseased PISF. Doxycycline (50 micro m and 250 micro m), chemically modified non-antimicrobial tetracycline (CMT-3) (50 micro m and 100 micro m), clodronate (a bisphosphonate, 20 micro m and 500 micro m) and the cyclic CTT (CTTHWGFTLC)-peptide (125 micro m and 250 micro m), all known broad-spectrum or selective MMP-inhibitors, did not inhibit the activity of human recombinant MMP-7; only marimastat (1 micro m and 5 micro m) inhibited MMP-7. DISCUSSION: Increased immunoreactivities of the active MMP-8 and MMP-7 species in PISF from diseased peri-implantitis lesions eventually reflect the stage and course of peri-implantitis; MMP-7 may potentially act as MMP-8 and defensin activator in diseased PISF. CONCLUSION: The elevated levels of MMP-8 and matrilysin-1/MMP-7 were identified in active forms in diseased PISF, but MMP-7 was less prominent. MMP inhibitors, potential future tissue protective drugs, seemingly do not interfere with the defensive antibacterial action of MMP-7.

Activation of matrix metalloproteinase-8 by membrane type 1-MMP and their expression in human tears after photorefractive keratectomy.

PURPOSE: Matrix metalloproteinases (MMPs) play a central role in the wound-healing process. The objective of this study was to identify and characterize the levels and molecular forms of human tear fluid collagenase-2 (MMP-8) and membrane type 1-MMP (MT1-MMP or MMP-14) in patients who had undergone excimer laser photorefractive keratectomy (PRK) and in healthy subjects. Whether MT1-MMP activates pro-MMP-8 was also determined. METHODS: Tear fluid samples were collected with scaled and blunted microcapillaries from healthy control subjects and, on the second postoperative day, from patients who had undergone PRK. Time and the volume collected were registered. Molecular forms and levels of pro and active MMP-8 and MT1-MMP in these samples were determined by Western immunoblot analysis, quantitated by computer scanning. The concentration of MMP-8 was also determined by immunofluorescence assay. The conversion of pure human polymorphonuclear neutrophil (PMN) pro-MMP-8 to the active form by the catalytic domain of MT1-MMP was studied by Western immunoblot analysis. RESULTS: The tear fluid flow was increased after PRK. Tear fluid flow-corrected excretion of MMP-8 was significantly higher in PRK-treated patients, as assessed by immunofluorescence assay and quantitative Western immunoblot analysis. The major MMP-8 species detected in tears of both PRK-treated patients and healthy control subjects represented latent and active 75- and 65-kDa highly glycosylated MMP-8 isoforms. The less-glycosylated 45- to 55-kDa MMP-8 isoform was not detectable. Tear fluid flow-corrected secretion of MT1-MMP was significantly higher in PRK-treated patients. Soluble 80-kDa MT1-MMP immunoreactivities were detected in tears of both healthy control subjects and PRK-treated patients, and may represent a complex captured by tissue inhibitor of metalloproteinase (TIMP)-2. Human PMN pro-MMP-8 was converted to the active form by MT1-MMP, and TIMP-2 prevented this activation. CONCLUSIONS: Corneal renewal eventually occurs at a high rate and is affected by the rate of corneal collagen and other matrix protein breakdown. Accordingly, tear fluid MMP-8 and MT1-MMP levels were shown to be constantly high in normal subjects. With PRK, a fast wound-healing process was associated with even higher MMP-8 and MT1-MMP levels and their activation. The results suggest a role for a MMP-8 and MT1-MMP network in the corneal wound-healing cascade. Furthermore, MT1-MMP (MMP-14) seems to activate pro-MMP-8.

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.