Impact of Inflammatory Markers and Senescence-Associated Secretory Phenotype in the Gingival Crevicular Fluid on the Outcomes of Periodontal Regeneration.

The aim of this study was to test the molecular expression profile (senescence-associated secretory phenotype; SASP) in gingival crevicular fluid (GCF) prior to surgery in relation to the distribution of clinical success of periodontal regeneration. Forty consecutive patients presenting sites with residual probing pocket depth (PPD) ≥ 6 mm and intrabony defects ≥ 3 mm were treated through a minimally invasive surgical technique. Pre-operatively, GCF was sampled for inflammatory biomarker analysis related to SASP [interleukin (IL)-1ß, IL-6, and IL-12; matrix-metalloproteinases (MMP)-8 and -9]. Better or worse responders were classified depending on the achievement of a composite outcome measure at 1-year [COM; PPD ≤ 4 mm and clinical attachment gain (CAL) gain ≥ 3 mm]. Correlation analyses and logistic regression models were performed. Periodontal regeneration led to significant improvements in mean clinical and radiographic parameters. Teeth achieving COM presented significantly lower amounts of SASP factors compared with non-successful teeth. Higher CAL gain, PPD reduction, and radiographic bone fill were negatively correlated with IL-1ß and MMP-8 and -9 (p < 0.001), while IL-12 showed a direct relationship with CAL gain (p = 0.005) and PPD reduction (p = 0.038). Sites expressing higher SASP expression in the GCF before periodontal regeneration achieved worse clinical and radiographic outcomes.

Odontoblast-like MDPC-23 cells produce pro-inflammatory IL-6 in response to lipoteichoic acid and express the antimicrobial peptide CRAMP.

Objective: Odontoblasts are thought to be involved in innate immunity but their precise role in this process is not fully understood. Here, we assess effects of lipopolysaccharide (LPS) and lipoteichoic acid (LTA), produced by Gram-negative and Gram-positive bacteria, respectively, on matrix metalloproteinase-8 (MMP-8), interleukin-6 (IL-6) and cathelin-related antimicrobial peptide (CRAMP) expression in odontoblast-like MDPC-23 cells.Material and methods: Gene activity and protein production was determined by quantitative real-time RT-PCR and ELISA, respectively. Cellular expression of CRAMP was determined by immunocytochemistry.Results: Stimulation with LTA (5 and 25 µg/ml) but not LPS (1 and 5 µg/ml) for 24 h enhanced IL-6 mRNA expression. The LTA-induced up-regulation of IL-6 mRNA levels was associated with increased IL-6 protein levels. Stimulation with either LPS or LTA for 24 h lacked effect on both MMP-8 transcript and protein expression. Immunocytochemistry disclosed that MDPC-23 cells expressed immunoreactivity for CRAMP. MDPC-23 cells showed mRNA expression for CRAMP, but stimulation with either LPS or LTA did not modulate CRAMP transcript expression.Conclusions: We show that MDPC-23 cells possess immune-like cell properties such as LTA-induced IL-6 production and expression of the antimicrobial peptide CRAMP, suggesting that odontoblasts may modulate innate immunity via these mechanisms.

Comparative Analysis of MMP-8 and MMP-9 Concentrations in Crevicular and Peri-Implants Sulcular Fluids.

The concentrations of MMP-8 and MMP-9 were measured in the crevicular and the peri-implant sulcular fluids at the different stages of the prosthetic treatment. The concentration MMP-8 and MMP-9 in the peri-implant sulcular fluids were significantly higher (p<0.05) then in the gingival crevicular fluid. The determined parameters are the references values for dynamic observation over the functional state of the dental "implant-bone-soft" tissue system. The detected the correlations attest to synergy between secretion of MMP-8 and MMP-9 in the peri-implant sulcular fluid and allow analysis of the dependence of the secretion of these metalloproteinases on clinical and physiological peculiarities of the gingiva, which will help to better customize implant-supported prosthetic treatment of the patients.

Association of mRNA Levels of IL6, MMP-8, GSS in Saliva and Pyelonephritis in Children.

Nowadays, saliva is a subject of growing scientific interest because of its definite advantages as diagnostic medium. The aim of our study was to investigate the diagnostic potential and reliability of messenger RNAs (mRNAs) of selected genes-interleukin-6 (IL-6), matrix metalloproteinase-8 (MMP-8) and glutathione synthetase (GSS)-as salivary markers in children with diagnosed pyelonephritis and to correlate their levels with typical urine para-clinical indicators of the disease. Analysis of the mRNA levels for IL-6, MMP-8 and GSS in 28 children hospitalized with the diagnosis of pyelonephritis was conducted applying the method of quantitative reverse transcription polymerase chain reaction (RT-qPCR). In the study group (n = 28), IL-6 mRNA levels demonstrated 64-fold increase (p < 0.001). MMP-8 and GSS mRNA levels were increased in 12 samples in patients with pyelonephritis 3.27 (p < 0.01) and 1.94 (p < 0.001) times, respectively. We found a strong and significant correlation (p < 0.001) between the investigated mRNA for IL-6 and MMP-8, IL-6 and GSS, MMP-8 and GSS. Moderate degree of correlation was established between IL-6 and the typical para-clinical indicator of leucocytes (0.43, p < 0.05) and between GSS and leucocytes (0.54, p < 0.01). Salivary IL-6, MMP-8 and GSS mRNA levels in combination with urine test analysis could be useful diagnostic tool for the very distributed disorder of pyelonephritis in childhood.

Comparative Role of Matrixins in Diagnostics of Parotid Gland Tumors.

The benign and malignant neoplasms in parotid gland have similar clinical presentations despite different tumor growth rates. The study compared the clinical and morphological data as well as the results of ELISA for MMP-2, MMP-8, MMP-9, TIMP-1, and TIMP-2 in salivary fluid yielded during primary examination of the patients with pleomorphic adenoma and adenocarcinoma of parotid gland. The examined biomarkers detected in salivary fluid in patients with various cancer types differed significantly (p≤0.05). The correlations between clinical identification of adenoma or adenocarcinoma, on the one hand, and the levels of MMP-8, TIMP-1, and TIMP-2, on the other hand, makes it possible to use the latter as biomarkers for early detection and comprehensive noninvasive differential diagnostics of these neoplasms.

Thioredoxin fusion construct enables high-yield production of soluble, active matrix metalloproteinase-8 (MMP-8) in Escherichia coli.

Matrix metalloproteinases (MMPs) are crucial proteases in maintaining the health and integrity of many tissues, however their dysregulation often facilitates disease progression. In disease states these remodeling and repair functions support, for example, metastasis of cancer by both loosening the matrix around tumors to enable cellular invasion and by affecting proliferation and apoptosis, and they promote degradation of biological restorations by weakening the substrate to which the restoration is attached. As such, MMPs are important therapeutic targets. MMP-8 participates in cancer, arthritis, asthma and failure of dental fillings. MMP-8 differs from other MMPs in that it has an insertion that enlarges its active site. To elucidate the unique features of MMP-8 and develop selective inhibitors to this therapeutic target, a stable and active form of the enzyme is needed. MMP-8 has been difficult to express at high yield in a soluble, active form. Typically recombinant MMPs accumulate in inclusion bodies and complex methods are applied to refold and purify protein in acceptable yield. Presented here is a streamlined approach to produce in Escherichia coli a soluble, active, stable MMP-8 fusion protein in high yield. This fusion shows much greater retention of activity when stored refrigerated without glycerol. A variant of this construct that contains the metal binding claMP Tag was also examined to demonstrate the ability to use this tag with a metalloprotein. SDS-PAGE, densitometry, mass spectrometry, circular dichroism spectroscopy and an activity assay were used to analyze the chemical integrity and function of the enzyme.

Statin intake is associated with MMP-1 level in gingival crevicular fluid of patients with periodontitis.

BACKGROUND: This study was conducted to assess whether statin intake is associated with clinical parameters of periodontitis and matrix metalloproteinase (MMP) levels in gingival crevicular fluid (GCF) of non-diabetic and diabetic patients. METHODS: We first determined the effect of simvastatin on MMP expression in mononuclear cells. We then recruited 117 non-diabetic and diabetic patients, who all had periodontitis and took or did not take statin, and measured periodontal probing depth (PPD) and clinical attachment level (CAL), and collected gingival crevicular fluid (GCF) to quantify MMPs. RESULTS: The in vitro studies showed that simvastatin potently inhibited the expression of MMP-1, MMP-8, and MMP-9 upregulated by lipopolysaccharide (LPS) and high glucose in mononuclear cells. The patient study showed that, after adjusting for age and smoking status, PPD in diabetic patients on statin was significantly less than that in diabetic patients not on statin. MMP-1 level in GCF of non-diabetic and diabetic patients on statin was lower than that of non-diabetic and diabetic patients not on statin, respectively. No difference was found for MMP-8 and -9 levels in GCF. CONCLUSION: Statin intake is associated with reduced PPD in diabetic patients and MMP-1 level in GCF in either non-diabetic or diabetic patients.

[The relationship of molecular genetic markers with clinical signs and risk factors of periodontitis]. / Vzaimosvyaz' molekulyarno-geneticheskikh markerov s klinicheskimi priznakami i faktorami riska razvitiya parodontita.

The study revealed positive correlation between bleeding on probing and teeth loss risk with periodontal hypercolonization by Porphyromonas gingivalis, Prevotella intermedia and Treponema denticola. Pathological tooth mobility was associated with hypercolonization by P. intermedia and Tannerella forsythensis. Expression of IL8, TNF-α, MMP8 and MMP9 genes was also assessed in patient groups divided according to the depth of periodontal pockets and-the severity of chronic periodontitis revealing IL8 as positive diagnostic marker.

Induction of IL-6 and MMP-8 in human periodontal fibroblasts by static tensile strain.

OBJECTIVES: Mechanical loading is a potential activator of inflammation and able to stimulate factors for periodontal and alveolar bone destruction. Aim of this study was to investigate the inflammatory response and synthesis of proteinases by human periodontal ligament fibroblast (HPdLF) dependent on different strengths of static tensile strain (STS). MATERIALS AND METHODS: HPdLFs were loaded with different STS strengths (1, 5, and 10 %) in vitro. Gene expressions of cyclooxygenase (COX)-2 and interleukin (IL)-6 were analyzed by quantitative real-time polymerase chain reaction. Production of IL-6, prostaglandin E2 (PGE2), matrix metalloproteinase (MMP)-8, and tissue inhibitors of matrix metalloproteinase (TIMP)-1 were measured by enzyme-linked immunosorbent assay. Receptor activator of nuclear factor-kappa ligand (RANKL) synthesis was detected by immunocytochemical staining. RESULTS: Ten percent STS led to an increased gene expression of IL-6 and COX-2 (34.4-fold) in HPdLF, and 1 and 5 % STS slightly reduced the gene expression of IL-6. Synthesis of IL-6 was significantly reduced by 1 % STS and stimulated by 10 % STS. Ten percent STS significantly induced PGE2 production. RANKL was not detectable at any strength of STS. MMP-8 synthesis showed significantly higher values only at 10 % STS, but TIMP-1 was stimulated by 5 and 10 % STS, resulting into highest TIMP-1/MMP-8 ratio at 5 % STS. CONCLUSIONS: High-strength STS is a potent inducer of periodontal inflammation and MMP-8, whereas low-strength STS shows an anti-inflammatory effect. Moderate-strength STS causes the highest TIMP-1/MMP-8 ratio, leading to appropriate conditions for reformation of the extracellular matrix. CLINICAL RELEVANCE: Furthermore, this study points out that the strength of force plays a pivotal role to achieve orthodontic tooth movement without inducing periodontal inflammation and to activate extracellular matrix regeneration.

Influence of MMP-8 promoter polymorphism in early osseointegrated implant failure.

OBJECTIVE: Dental implants consist in the treatment of choice to replace tooth loss. The knowledge that implant loss tends to cluster in subsets of individuals may indicate that host immuneinflammatory response is influenced by genetic factors. In fact, genetic polymorphisms influence the osseointegration process. The objective of this study was investigate the possible relationship between C-799T polymorphism in matrix metalloproteinase 8 (MMP-8) gene and early implant failure in nonsmoker patients. METHODS AND MATERIALS: Subjects were divided into two groups: control group (100 patients with one or more healthy implants) and test group (80 patients that had suffered one or more early implant failures). Genomic DNA from oral mucosa was amplified by PCR and analyzed by restriction endonucleases. The significance of the differences in observed frequencies of polymorphisms was assessed by Chi-square. RESULTS: Statistical analysis shows that in the MMP-8 gene, the T allele in 76.25% in the test group and the T/T genotype, 63.75% in the same group, may predispose to early loss of implants osseointegrated. CONCLUSION: These results suggest that polymorphism in the promoter region of MMP-8 gene is associated with early implant failure. This polymorphism can be a genetic marker to risk of implant loss. CLINICAL RELEVANCE: The determination of this genetic pattern in osseointegration would enable the identification of individuals at higher risk to loss implant. Thus, genetic markers will be identified, contributing to an appropriate preoperative selection and preparation of strategies for prevention and therapy individualized to modulate the genetic markers and increase the success rate of treatments.

Sequential IL-23 and IL-17 and increased Mmp8 and Mmp14 expression characterize the progression of an experimental model of periodontal disease in type 1 diabetes.

Molecular mechanisms responsible for periodontal disease (PD) and its worsening in type 1 Diabetes Mellitus (DM1) remain unknown. Cytokine profile and expression levels of collagenases, Mmp14, and tissue inhibitors were determined, as were the numbers of neutrophils and macrophages in combined streptozotocin-induced DM1 and ligature-induced PD models. Increased IL-23 (80-fold) and Mmp8 expression (25-fold) was found in DM1. Ligature resulted in an IL-1ß/IL-6 profile, increased expression of Mmp8, Mmp13, and Mmp14 (but not Mmp1), and transient expression of Timp1 and Reck in non-diabetics. PD in DM1 involved IL-1ß (but not IL-6) and IL-23/IL-17, reduced IL-6 and IL-10, sustained Mmp8 and Mmp14, increased Mmp13 and reduced Reck expression in association with 20-fold higher counts of neutrophils and macrophages. IL-23 and Mmp8 expression are hallmarks of DM1. In association with the IL-1/IL-6 (Th1) response in PD, one found a secondary IL-17 (Th17) pathway in non-diabetic rats. Low IL-6/TNF-α suggest that the Th1 response was compromised in DM1, while IL-17 indicates a prevalence of the Th17 pathway, resulting in high neutrophil recruitment. Mmp8, Mmp13, and Mmp14 expression seems important in the tissue destruction during PD in DM1. PD-associated IL-1/IL-6 (Th1), IL-10, and Reck expression are associated with the acute-to-chronic inflammation transition, which is lost in DM1. In conclusion, IL-23/IL-17 are associated with the PD progression in DM1.

Effects of relaxin on relapse and periodontal tissue remodeling after experimental tooth movement in rats.

The relapse of teeth that have moved during orthodontic treatment is a major clinical issue with respect to the goals of successful treatment. Relaxin has an influence on many physiologic processes, such as collagen turnover. In this study, we determined the effects of relaxin on the relapse and remodeling of periodontal tissue after experimental tooth movement in rats, and we explored the molecular mechanism underlying these processes. To induce experimental tooth movement in rats, 10 g of orthodontic force was applied to the molars. After 14 days, the spring was removed, and then animals began receiving relaxin at a dose of 500 ng/ml for 1 week. The results were evaluated by micro-computed tomography and immunofluorescence staining. In addition, the effects of matrix metalloproteinase (MMP)-1 and MMP-8 production were investigated in human periodontal ligament (hPDL) cells in vitro. The expression of MMP-1 and MMP-8 was analyzed by real-time polymerase chain reaction and enzyme-linked immunosorbent assay. Furthermore, we demonstrated the signaling pathways involved in relaxin-regulated MMPs expression. The relapse distances and percentages were significantly decreased in the experimental group compared with the controls in vivo. A double-immunofluorescence analysis for Col-I/MMP-1 and Col-I/MMP-8 detected the expression of relaxin in the PDL. Relaxin significantly increased the MMP-1 and MMP-8 expression in a time-dependent manner in hPDL cells in vitro. Furthermore, a p38 inhibitor (SB203580) significantly inhibited the MMP-1 and MMP-8 expression. Our results indicated that relaxin modulates the collagen metabolism, and this hormone may therefore be useful to prevent orthodontic relapse following orthodontic treatment.

Matrix metalloproteinase-8 expression in periodontal tissues surgically removed from diabetic and non-diabetic patients with periodontal disease.

BACKGROUND: Although it is known that periodontal matrix metalloproteinase-8 (MMP-8) expression is associated with periodontal disease, the information concerning the periodontal MMP-8 expression in diabetic patients with periodontal disease is insufficient. MATERIALS AND METHODS: Periodontal tissue specimens were collected from seven patients without periodontal disease and diabetes (Group 1), 15 patients with periodontal disease alone (Group 2) and 10 patients with both periodontal disease and diabetes (Group 3). The frozen sections were prepared and MMP-8 protein expression was detected using immunohistochemistry and quantified. For in vitro study, human U937 mononuclear cells were pre-exposed to normal or high glucose and then treated with lipopolysaccharide (LPS). RESULTS: The nonparametric Kruskal-Wallis test showed that the difference in MMP-8 protein levels among the three groups were statistically significant (p = 0.003). Nonparametric analysis using Jonckheere-Terpstra test showed a tendency of increase in periodontal MMP-8 levels across Group 1 to Group 2 to Group 3 (p = 0.0002). In vitro studies showed that high glucose and LPS had a synergistic effect on MMP-8 expression. CONCLUSION: Our current study showed an increasing trend in MMP-8 protein expression levels across patients without both periodontal disease and diabetes, patients with periodontal disease alone and patients with both diseases.

Peri-Implant Surgical Treatment Downregulates the Expression of sTREM-1 and MMP-8 in Patients with Peri-Implantitis: A Prospective Study.

sTREM-1 and its ligand PGLYRP1 play an essential role in the inflammatory process around teeth and implants. In this study, we aimed to evaluate the impact of peri-implant treatment on the salivary levels of the sTREM-1/PGLYRP-1/MMP-8 axis after 3 months. A total of 42 participants (with a mean age of 61 years old ± 7.3) were enrolled in this longitudinal study, 24 having peri-implant mucositis (MU) and 18 having peri-implantitis (PI). Clinical peri-implant parameters, such as probing pocket depth (PPD), % of plaque, and bleeding on probing (BOP), and the whole unstimulated saliva samples were evaluated at baseline and 3 months after treatment. The MU group received nonsurgical peri-implant treatment, while the PI group received open-flap procedures. The levels of sTREM-1, PGLYRP-1, MMP-8, and TIMP-1 were analyzed using enzyme-linked immunosorbent assays. BOP, plaque levels, and PPD significantly reduced after treatment in both groups. A significant decrease in the salivary levels of sTREM-1, MMP-8, and TIMP-1 in the PI group and PGLYRP1 and TIMP-1 in the MU group were observed. Salivary levels of sTREM-1 were significantly reduced in patients with PI but not with MU. Additionally, peri-implant treatment had a significantly higher impact on MMP-8 reduction in patients with PI than in those with MU.

Reduced expression of lipopolysaccharide-induced CXC chemokine in Porphyromonas gingivalis-induced experimental periodontitis in matrix metalloproteinase-8 null mice.

BACKGROUND AND OBJECTIVE: Matrix metalloproteinase-8 (MMP-8) is a central mediator in chronic periodontitis. Recently developed MMP-8-deficient mice show an impaired polymorphonuclear neutrophil response and more severe alveolar bone loss in Porphyromonas gingivalis-induced experimental periodontitis. The main mediators involved in neutrophil and monocyte/macrophage recruitment and in bone loss include lipopolysaccharide-induced CXC chemokine (LIX/CXCL5), stromal-derived factor-1/CXC chemokine ligand 12 (SDF1/CXCL12) and RANKL. Therefore, the aim of this study was to characterize the expression of LIX/CXCL5, SDF1/CXCL12 and RANKL in Porphyromonas gingivalis-induced experimental periodontitis in MMP-8⁻/⁻ (knockout) and wild-type mice. MATERIAL AND METHODS: MMP-8 null and WT P. gingivalis-infected and uninfected mice were included. Histopathological changes were assessed and LIX/CXCL5, SDF1/CXCL12 and RANKL were immunodetected and quantified. RESULTS: Typical histopathological features of chronic periodontitis were seen in P. gingivalis-infected groups. LIX/CXCL5 expression was restricted to the gingival papilla in all four groups. Significantly lower expression of LIX/CXCL5 was seen in the knockout group compared with the wild-type infected group (p < 0.05). SDF1/CXCL12 and RANKL expression was mainly localized to the alveolar crest, including inflammatory leukocytes, vascular endothelium, osteoblasts and osteoclasts. Significant increases of SDF1/CXCL12 and RANKL were seen in both knockout and wild-type P. gingivalis-infected groups compared with uninfected groups (p < 0.05). CONCLUSION: RANKL and SDF1/CXCL12 are up-regulated in P. gingivalis-induced periodontitis and they appear to be associated with the pathogenesis of the disease. MMP-8 is associated with a reduced expression of LIX/CXCL5 in the P. gingivalis-induced experimental periodontitis model.

MMP-8 -799 C>T genetic polymorphism is associated with the susceptibility to chronic and aggressive periodontitis in Taiwanese.

AIM: Matrix metalloproteinase (MMP)-8 is a protease that degrades numerous extracellular molecules and has been implicated in the pathogenesis of periodontitis. Polymorphism in the MMP-8 could affect the susceptibility to disease. Our aim was to evaluate the association between periodontitis and MMP-8 -799 C>T polymorphism. MATERIAL AND METHODS: Genomic DNA was obtained from 361 chronic periodontitis patients (CP), 96 aggressive periodontitis patients (AgP), and 106 periodontally healthy controls (HC). MMP-8 -799 C>T polymorphism was determined using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). RESULTS: The frequencies of genotypes in diseased groups were similar but were significantly different from those in the HC. Multivariate logistic regression analysis with adjustment for age, gender and smoking indicated that increased risks of AgP and CP were associated with the -799 T allele (in AgP, adjusted OR = 1.99, p = 0.04; in CP, adjusted OR = 1.87, p = 0.007). To avoid the confounded effect of smoking on MMP-8 polymorphism to periodontitis, the analysis was conducted on non-smokers and the associations were significant. CONCLUSIONS: These results suggested that non-smoking Taiwanese with the MMP-8 -799 T allele were associated with the risks of both CP and AgP. Further studies in other ethnic populations are necessary.

Expression of MMP-8 and MMP-13 in the development of periradicular lesions.

AIM: To elucidate the expressions of MMP-8 and MMP-13 in experimentally induced rat periradicular lesions by means of the reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemical staining. METHODOLOGY: Thirty rats were used and periradicular lesions in mandibular first molar teeth were established following pulp exposure. The animals were sacrificed at 0 (no exposure control), 1, 2, 3, 4 and 6 weeks after pulp exposure. The right molars were used for RT-PCR analysis of MMP-8 and MMP-13. The left molars were subjected to immunohistochemical staining with both MMPs. The areas of these lesions were measured histometrically, and the numbers of both reactive cells in the periapical portion were counted per unit area. Significant differences were analysed by the Mann-Whitney U-test. RESULTS: MMP-8 gene expression gradually increased from 2 to 4 weeks, but slightly decreased at 6 weeks. MMP-13 gene expression gradually increased from 1 to 3 weeks. At 4 and 6 weeks, the level of expression was as high as that at 3 weeks. Immunohistochemically, MMP-8 was first detected at 2 weeks and gradually increased until 4 weeks. MMP-13 gradually increased from 1 to 4 weeks. Both MMPs decreased at 6 weeks. The area of the periradicular lesions gradually increased from 1 to 4 weeks, showing a large increase in week 2 and 3 in particular, but then decreased in week 6. MMP-13-expressing cells were significantly greater than MMP-8-positive cells at week 1 and 2. CONCLUSIONS: These findings indicate that MMP-8 and MMP-13 were related to the development of periradicular lesions. It is suggested that MMP-13 increased from an early stage during their development and that MMP-8 is involved in the progression of tissue destruction including bone resorption.

Loss of mutual protection between human osteoclasts and chondrocytes in damaged joints initiates osteoclast-mediated cartilage degradation by MMPs.

Osteoclasts are multinucleated, bone-resorbing cells. However, they also digest cartilage during skeletal maintenance, development and in degradative conditions including osteoarthritis, rheumatoid arthritis and primary bone sarcoma. This study explores the mechanisms behind the osteoclast-cartilage interaction. Human osteoclasts differentiated on acellular human cartilage expressed osteoclast marker genes (e.g. CTSK, MMP9) and proteins (TRAP, VNR), visibly damaged the cartilage surface and released glycosaminoglycan in a contact-dependent manner. Direct co-culture with chondrocytes during differentiation increased large osteoclast formation (p < 0.0001) except when co-cultured on dentine, when osteoclast formation was inhibited (p = 0.0002). Osteoclasts cultured on dentine inhibited basal cartilage degradation (p = 0.012). RNA-seq identified MMP8 overexpression in osteoclasts differentiated on cartilage versus dentine (8.89-fold, p = 0.0133), while MMP9 was the most highly expressed MMP. Both MMP8 and MMP9 were produced by osteoclasts in osteosarcoma tissue. This study suggests that bone-resident osteoclasts and chondrocytes exert mutually protective effects on their 'native' tissue. However, when osteoclasts contact non-native cartilage they cause degradation via MMPs. Understanding the role of osteoclasts in cartilage maintenance and degradation might identify new therapeutic approaches for pathologies characterized by cartilage degeneration.

Levels of Gene Expression of Immunological Biomarkers in Peri-Implant and Periodontal Tissues.

This study compared the gene expression of the immunoinflammatory markers interleukin (IL)-6, IL-1ß, and tumor necrosis factor alpha (TNF-α), the matrix metalloproteinases (MMP)-1, -2, -8, and -9, and the tissue inhibitors of matrix metalloproteases (TIMP)-1 and -2 in the gingival tissue of individuals with periodontal and peri-implant disease. The study population included individuals with four periodontal statuses: periodontal health (PH group, n = 20); periodontitis (P group, n = 20); peri-implant health (PIH group, n = 20), and peri-implantitis (PI group, n = 20). Gingival biopsies were collected from one tooth per patient according to the inclusion criteria of each group. The mRNA levels of IL-6, IL-1ß, TNF-α, MMP-1, MMP-2, MMP-8, MMP-9, TIMP-1, and TIMP-2 were evaluated by qPCR. The levels of IL-1ß were significantly higher in the PI group when compared to the other groups (p < 0.05), while the levels of IL-6 were significantly higher in the groups with periodontal and peri-implant disease when compared with the healthy groups (p < 0.05); however, the levels of IL-6 did not differ between the PI and P groups (p > 0.05). For all other studied biomarkers, no significant differences were observed between groups (p > 0.05). IL-6 and IL-1ß presented higher levels of mRNA in diseased periodontal and peri-implant tissues. However, the expression of metalloproteinases and their inhibitors did not differ between the different periodontal statuses.

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.