Hsi‐Ming Lee

Matrix metalloproteinases (MMPs) form a family of enzymes that mediate multiple functions both in the tissue destruction and immune responses related to periodontal inflammation. The expression and activity of MMPs in non-inflamed periodontium is low but is drastically enhanced to pathologically elevated levels due to the dental plaque and infection-induced periodontal inflammation. Soft and hard tissue destruction during periodontitis and peri-implantitis are thought to reflect a cascade of events involving bacterial virulence factors/enzymes, pro-inflammatory cytokines, reactive oxygen species and MMPs. However, recent studies suggest that MMPs can also exert anti-inflammatory effects in defence of the host by processing anti-inflammatory cytokines and chemokines, as well as by regulating apoptotic and immune responses. MMP-inhibitor (MMPI)-drugs, such as doxycycline, can be used as adjunctive medication to augment both the scaling and root planing-treatment of periodontitis locally and to reduce inflammation systematically. Furthermore, MMPs present in oral fluids (gingival crevicular fluid (GCF), peri-implant sulcular fluid (PISF), mouth-rinses and saliva) can be utilized to develop new non-invasive, chair/bed-side, point-of-care diagnostics for periodontitis and dental peri-implantitis.

BACKGROUND: Administration of subantimicrobial dose doxycycline (SDD) to chronic periodontitis (CP) patients has repeatedly been found to reduce mammalian collagenase and other matrix metalloproteinase (MMP) activity in gingival tissues and crevicular fluid, in association with clinical efficacy, without the emergence of antibiotic-resistant bacteria either orally or extra-orally. More recently, SDD adjunctive to repeated mechanical debridement resulted in dramatic clinical improvement in patients (>50% smokers) with generalized aggressive periodontitis. As an additional pharmacologic approach, non-steroidal anti-inflammatory drugs (NSAIDs) can reduce gingival inflammation and alveolar bone resorption, at least under experimental conditions. In the current study, we determined the effect of administering a combination (combination) of these two host-modulating drugs (SDD plus low-dose NSAID) to CP patients, on selected neutral proteinases in gingiva, enzymes believed to mediate periodontal breakdown. Earlier preliminary studies in humans with bullous pemphigoid, which is also associated with excessive levels of host-derived proteinases including MMPs, indicated improved clinical efficacy of combination therapy. METHODS: Nineteen CP patients, scheduled for mucoperiosteal flap surgery bilaterally in the maxillary arch, were randomly distributed into three experimental groups administered either 1) low-dose flurbiprofen (LDF) alone, 50 mg q.d.; 2) SDD (20 mg b.i.d.) alone; or 3) a combination of SDD plus LDF (combination). The gingival tissues were biopsied during surgery from right and left maxillary posterior sextants, before and after a 3-week regimen of medication, respectively. The tissues were then extracted, the extracts partially purified, then analyzed for the endogenous proteinase inhibitor, alpha1-PI, and its breakdown product, and for host-derived matrix metalloproteinases (i.e., collagenases, gelatinases) and neutrophil elastase activities. RESULTS: Short-term therapy with SDD alone produced a significant reduction and LDF alone produced no reduction in host-derived neutral proteinases. However, the combination therapy produced a statistically significant synergistic reduction of collagenase, gelatinase, and serpinolytic (alpha1-PI degrading) activities (69%, 69%, and 75% reductions, respectively) and a lesser reduction of the serine proteinase, elastase (46%). CONCLUSIONS: Consistent with previous studies on animal models of chronic destructive disease (e.g., rheumatoid arthritis), the SDD and NSAID combination therapy synergistically suppressed MMP and other neutral proteinases in the gingiva of CP patients. A mechanism, suggested by earlier animal studies, involves the NSAID, in the combination regimen, increasing the uptake of the tetracycline-based MMP inhibitor in the inflammatory lesion, thus synergistically enhancing the efficacy of this medication.

OBJECTIVE: To compare collagenase activity and collagenolytic matrix metalloproteinase (MMP) levels in gingival crevicular fluid (GCF) and in peri-implant sulcular fluid (PISF) in gingivitis (G), chronic periodontitis (CP), and peri-implantitis (PI) human subjects. MATERIAL AND METHODS: GCF and PISF were collected on filter paper strips, volume was determined, and samples were extracted in buffer containing general proteinase but not MMP inhibitors. Collagenase activity was measured using a DNP-synthetic octapeptide, and molecular and activation forms of collagenase-2 by Western immunoblotting. RESULTS: GCF from CP and G sites exhibited elevated collagenase activity and flow, but collagenase concentrations expressed per microl were not significantly different between the healthy and G sites. Minimal fluid was obtained from healthy PISF, and collagenase concentration was the same or lower than in healthy GCF. Although PISF flow was 34% lower than GCF flow in CP subjects, collagenase concentration in CP and in PI sites was 78% and 971% greater, respectively, than in the appropriate healthy sites. Western immunoblot revealed MMP-8 in both PISF and GCF; fibroblast-type MMP-8 was not detected in healthy GCF and PISF. Immunoreactivity level and inactive and activated forms of PMN-type MMP-8 in GCF and PISF increased with the severity of periodontitis and peri-implantitis. Enhanced levels of fibroblast-type MMP-8 in active form were detected only in severe CP GCF and PI PISF. CONCLUSIONS: Peri-implantitis PISF contained higher collagenase-2 levels and activity than GCF from similar deep CP sites. GCF and PISF from severe CP and PI exhibited the highest activation of MMP-8 isoenzymes species (PMN and fibroblast-type).

Introduction. Impaired wound-healing in diabetics can lead to life-threatening complications, such as limb amputation, associated in part with excessive matrix metalloproteinase- (MMP-) mediated degradation of collagen and other matrix constituents. In the current study, a novel triketonic chemically modified curcumin, CMC2.24, was tested for efficacy in healing of standardized skin wounds in streptozotocin-induced diabetic rats. Initially, CMC2.24 was daily applied topically at 1% or 3% concentrations or administered systemically (oral intubation; 30 mg/kg); controls received vehicle treatment only. Over 7 days, the diabetics exhibited impaired wound closure, assessed by gross and histologic measurements, compared to the nondiabetic controls. All drug treatments significantly improved wound closure with efficacy ratings as follows: 1% 2.24 > systemic 2.24 > 3% 2.24 with no effect on the severe hyperglycemia. In subsequent experiments, 1% CMC2.24 "normalized" wound-healing in the diabetics, whereas 1% curcumin was no more effective than 0.25% CMC2.24, and the latter remained 34% worse than normal. MMP-8 was increased 10-fold in the diabetic wounds and topically applied 1% (but not 0.25%) CMC2.24 significantly reduced this excessive collagenase-2; MMP-13/collagenase-3 did not show significant changes. Additional studies indicated efficacy of 1% CMC2.24 over more prolonged periods of time up to 30 days.