Detection of tissue plasminogen activator (t-PA) and plasminogen activator inhibitor 2(PAI-2) in gingival crevicular fluid from healthy, gingivitis and periodontitis patients

Matrix Metalloproteinases in the Periodontium-Vital in Tissue Turnover and Unfortunate in Periodontitis

The extracellular matrix (ECM) is a complex non-cellular three-dimensional macromolecular network present within all tissues and organs, forming the foundation on which cells sit, and composed of proteins (such as collagen), glycosaminoglycans, proteoglycans, minerals, and water. The ECM provides a fundamental framework for the cellular constituents of tissue and biochemical support to surrounding cells. The ECM is a highly dynamic structure that is constantly being remodeled. Matrix metalloproteinases (MMPs) are among the most important proteolytic enzymes of the ECM and are capable of degrading all ECM molecules. MMPs play a relevant role in physiological as well as pathological processes; MMPs participate in embryogenesis, morphogenesis, wound healing, and tissue remodeling, and therefore, their impaired activity may result in several problems. MMP activity is also associated with chronic inflammation, tissue breakdown, fibrosis, and cancer invasion and metastasis. The periodontium is a unique anatomical site, composed of a variety of connective tissues, created by the ECM. During periodontitis, a chronic inflammation affecting the periodontium, increased presence and activity of MMPs is observed, resulting in irreversible losses of periodontal tissues. MMP expression and activity may be controlled in various ways, one of which is the inhibition of their activity by an endogenous group of tissue inhibitors of metalloproteinases (TIMPs), as well as reversion-inducing cysteine-rich protein with Kazal motifs (RECK).

Impact of scaling and root planing on salivary and serum plasminogen activator inhibitor-1 expression in patients with periodontitis with and without type 2 diabetes mellitus

BACKGROUND

Plasminogen activator inhibitor-1 (PAI-1) is significantly enhanced in insulin resistance and inflammation and ascribed as a proinflammatory marker. This study aimed to compare and correlate salivary and serum PAI-1 and alpha 2-macroglobulin (α2MG) in patients with periodontitis with and without type 2 diabetes mellitus (T2DM) and also appraise the consequence of periodontal treatment on these biomarkers.

METHODS

Sixty subjects enlisted were split into two groups; Group 1 consisted of 30 systemically healthy subjects with Stage II and III, generalized, Grade B, C periodontitis while Group 2 consisted of 30 patients with periodontitis and well-controlled T2DM (PDM). Salivary and serum PAI-1 and α2MG levels were estimated by enzyme-linked immunosorbent assay and allied with clinical parameters before and 3 months post non-surgical periodontal therapy (NSPT). Data were statistically analyzed using student t-test and Spearman correlation.

RESULTS

Analogous improvements in clinical periodontal markers were experienced in both groups after initial periodontal treatment. Estimates of salivary and serum PAI-1 and α2MG were higher among the PDM group compared with periodontitis alone at baseline. Significant diminution in estimates of biomarkers was noted 3 months after NSPT. In the PDM group, there was also an improvement in glycemic control.

CONCLUSIONS

NSPT positively impacted both groups. Noteworthy expression of salivary and serum PAI-1 in patients with periodontitis and diabetes insinuates a possible role of the adipokine in periodontal inflammation and glucose level regulation. Salivary PAI-1 could thus be used as a diagnostic biomarker to detect disease activity and to track periodontal therapy response.

Periodontitis and coronavirus disease 2019

The coronavirus disease 2019 caused by severe acute respiratory syndrome coronavirus 2 is usually a mild condition; however, in some cases it can result in severe sickness and even death. Thus, understanding the reasons behind these grave outcomes is of great importance. Coronavirus disease 2019 and periodontitis share some intriguing characteristics. They can both lead to systemic inflammation and alterations of coagulation pathways, and both share confounding factors, such as diabetes, hypertension, and obesity. Accordingly, a possible association between these conditions has been hypothesized in the literature. The objective of this review was to evaluate the scientific evidence linking these diseases and the possible underlying mechanisms. Evidence has shown that coronavirus disease 2019 presents oral manifestations and can even affect periodontal tissues. Moreover, some studies have shown a possible association between coronavirus disease 2019 severity and the presence of periodontitis. Current evidence suggests that this association could be explained through the direct role of periodontal bacteria in aggravating lung infections, as well as through the indirect effect of periodontitis in inducing systemic inflammation and priming of the immune system to an exacerbated reaction to severe acute respiratory syndrome coronavirus 2 infection. Future research is needed to confirm these observations and explore the possible role that periodontal care might play in the coronavirus disease 2019 pandemic.

Clinical and biochemical evaluation of oral irrigation in patients with peri-implant mucositis: a randomized clinical trial

OBJECTIVE

This randomized clinical trial aimed to compare the efficacy of an oral irrigator and an interdental brush in patients with peri-implant mucositis clinically and biochemically at different time points (at baseline and at the 2nd, 4th, and 12th weeks).

MATERIALS AND METHODS

Forty-five patients with at least one implant with peri-implant mucositis were included in the present study (n = 45). The patients were divided into three groups: oral irrigator + toothbrush (OI group, n = 15), interdental brush + toothbrush (IB group, n = 15), and toothbrush only (control) (C group, n = 15). The modified plaque index (mPlI), modified sulcus bleeding index (mSBI), probing pocket depth (PPD), probing attachment level (PAL), and bleeding on probing (BOP) were recorded at baseline and at the 2nd, 4th, and 12th weeks. The levels of interleukin 1 beta (IL-1β), transforming growth factor-beta (TGF-β), tissue-type plasminogen activator (t-PA), and plasminogen activator inhibitor-1 (PAI-1) were also determined in the peri-implant crevicular fluid samples biochemically.

RESULTS

The mSBI and t-PA at the 2nd week (p = 0.003; p = 0.003); the mPlI, mSBI, BOP, t-PA, and PAI-1 at the 4th week (p < 0.05; p < 0.001; p < 0.001; p = 0.015; p = 0.011); and the mPlI, mSBI, IL-1β, t-PA, and PAI-1 at the 12th week (p < 0.05; p < 0.001; p = 0.013; p < 0.001; p = 0.002) were significantly lower in the OI group compared with those in the C group. Meanwhile, PAI-1 at the 2nd week, mSBI at the 4th week, and t-PA at the 12th week were significantly lower in the OI group compared with those in the IB group (p < 0.001; p = 0.011; p = 0.003). At the 2nd, 4th, and 12th weeks, all other parameters were not statistically different in the three groups.

CONCLUSION

The clinical indexes (such as mSBI and BOP) that play an important role in the diagnosis of peri-implant mucositis showed the lowest means (although limited) in the OI group at all evaluation time points. Moreover, when the clinical and biochemistry results were interpreted altogether, it became apparent that the OI group exhibited similar or more effective results than the IB group in resolving peri-implant mucositis. In light of the foregoing, this study concluded that the use of an oral irrigator can be as effective as an interdental brush in interdental cleaning.

CLINICAL RELEVANCE

In this study, it is suggested that the regular use of an oral irrigator along with a toothbrush could be an appropriate alternative to other oral hygiene products such as dental floss and interdental brush for the management of peri-implant mucositis by preventing the accumulation of dental plaque (NCT03844035).

Periodontal health and disease: The contribution of genetics

Periodontitis is an infectious, inflammatory disease that is associated with a complex interplay between specific bacteria, host response, and environmental factors. Because of its high degree of familial aggregation, specifically for the more aggressive forms of the disease, genetics factors have been implicated in disease pathogenesis for several decades. This review provides an overview of what we currently know regarding the genetic and epigenetic contributions to periodontal disease and discusses future opportunities in the field.

Plasminogen activator inhibitor-1 polymorphisms as a risk factor for chronic periodontitis in North Indian population

Objectives

Impaired plasminogen activator inhibitor-1 (PAI-1), controlling coagulation and the fibrinolytic system is supposed to be involved in the pathogenesis of periodontitis. This study was performed to examine the association of PAI-1 gene polymorphisms with Chronic Periodontitis (CP) and alveolar bone loss severity involved with the disease and for understanding the role of genetic contributions in disease progression.

Methods

87 volunteers were included in the study. Genomic DNA was isolated from peripheral blood, subsequently, DNA samples were subjected to polymerase chain reaction and endonuclease digestion. Direct gene sequencing were performed for all the samples to identify genotype polymorphisms (rs 11560324) in the 3' untranslated region of PAI-1 gene. For bone loss assessment full mouth IOPA was taken.

Results

Statistical analysis showed that for SNP PAI-I in 3' UTR, genotype CC (homozygous mutant) and allele C (mutant) has a risk associated with CP, although statistically significant association was not found. An increased risk of association of disease severity with CG (heterozygous mutant) and CC (homozygous mutant) genotypes, i.e., an increased carriage rate of genotype CG and CC (homozygous mutant) was evident with the increase in the severity of CP, highlighting an increased susceptibility to CP due to this gene polymorphisms.

Conclusion

PAI-1 genotype has a risk association with CP and alveolar bone loss severity in North-Indian population.

Plasminogen activator activity in tears of pregnant women

Purpose

Plasminogen activator activity (PAA) in tears of pregnant women was investigated at various gestation times to assess the availability of plasminogen activator for aiding potential corneal wound healing processes during pregnancy.

Methods

PAA was measured by a spectrophotometric method. The analysis used 91 tear samples from pregnant and non-pregnant women, supplemented with 10 additional tear PAA measurements from non-pregnant women obtained in a previous study.

Results

Tear levels of PAA in pregnant women formed a bimodal distribution. Either the tear PAA level was zero or non-zero during pregnancy. When non-zero, the tear PAA level was dissociated from gestation time and not different than non-pregnant and post-pregnant levels. The frequency of occurrence of zero level tear PAA increased with gestation: 16%, 17% and 46% had zero tear PAA in samples taken from women in the first, second and third trimester, respectively.

Conclusions

Overall, of the tear samples taken from women during pregnancy, a total of 26% were at zero tear PAA. The remaining tear samples had non-zero tear PAA values throughout gestation equivalent to non-pregnant tear PAA values, suggesting local control of the source of PAA in tears. Given the importance of the plasminogen activator system in tears to wound healing in the cornea, and the high occurrence of zero tear PAA in our sample of pregnant women, elective corneal surgery would be contraindicated. If corneal surgery is nevertheless necessary, the tear PAA level would be worth checking and patients with low level should be closely observed during the postoperative period.

Relevance of the plasminogen system in physiology, pathology, and regeneration of oral tissues - From the perspective of dental specialties

Plasmin is a proteolytic enzyme that is crucial in fibrinolysis. In oral tissues, the plasminogen system plays an essential role in physiological and pathological processes, which in addition to fibrinolysis include degradation of extracellular matrix, inflammation, immune response, angiogenesis, tissue remodeling, cell migration, and wound healing. Oral tissues reveal a change in the plasminogen system during pathological processes such as periodontitis, peri-implantitis, or pulpitis, as well as in response to mechanical load. The plasminogen system is also a key element in tissue regeneration. The number of studies investigating the plasminogen system in dentistry have grown continuously in recent years, highlighting its increasing relevance in dental medicine. In this review, we present the diverse functions of the plasminogen system in physiology and its importance for dental specialists in pathology and regeneration. We thus provide an overview of the current knowledge on the role of the plasminogen system in the different fields of dentistry, including endodontics, orthodontics, periodontics, and oral surgery.

Variant of PAI-2 gene is associated with coronary artery disease and recurrent coronary event risk in Chinese Han population

Background

Plasminogen activator inhibitor −2 (PAI-2) is an important molecular that plays a crucial role in vascular homeostasis and constitutes a critical response mechanism to cardiovascular injury, such as atherosclerosis, coronary artery disease (CAD).

Methods

The aim of the current study was to explore the association between the variants in PAI-2 gene and CAD and its prognoses. The three variants (rs8093048, rs9946657, rs9320032) of the PAI-2 gene were detected in 407 patients with CAD and 518 control subjects. All patients with CAD underwent one-year follow-up for major adverse cardiac events (MACE).

Results

The frequencies of the TT genotype and T allele of rs8093048 was significantly higher in CAD patients than that in control subjects (7.6 % vs.3.5 %, P = 0.003, 28.1 % vs.21.7 %, P < 0.001, respectively). Multifactor logistic regression analysis showed that the TT genotype of rs8093048 was a risk factor for CAD (OR = 1.455, 95 % CI: 1.069-1.980, P = 0.017). In addition, the follow-up data showed that CAD patients with rs8093048 TT genotype had significantly higher rate of refractory angina and MACE than those with CC or CT genotype (P = 0.032, P = 0.009, respectively). Cox regression analysis showed that rs8093048 TT genotype was the risk factor for the MACE (Hazard ratio = 5.672, 95 % CI = 1.992-16.152, P = 0.001).

Conclusion

We firstly found that the variant of PAI-2 gene was associated with CAD and recurrent coronary event risk in Chinese Han population, in Xinjiang.

Acute Phase Proteins and Their Role in Periodontitis: A Review

Acute phase proteins are a class of proteins whose plasma concentration increase (positive acute phase proteins) or decrease (negative acute phase proteins) in response to inflammation. This response is called as the acute phase reaction, also called as acute phase response, which occurs approximately 90 minutes after the onset of a systemic inflammatory reaction. In Periodontitis endotoxins released from gram negative organisms present in the sub gingival plaque samples interact with Toll- like receptors (TLR) that are expressed on the surface of Polymorphonuclear leucocytes (PMNs) and monocytes which are in abundance in periodontal inflammation. The complex formed due to interaction of Endotoxins and TLR activates the Signal transduction pathway in both innate and adaptive immunity resulting in production of Cytokines that co- ordinate the local and systemic inflammatory response. The pro inflammatory cytokines originating at the diseased site activates the liver cells to produce acute phase proteins as a part of non specific response. The production of Acute phase proteins is regulated to a great extent by Cytokines such as IL-1, IL-6, IL-8, TNF-α and to a lesser extent by Glucocorticoid hormones. These proteins bind to bacteria leading to activation of complement proteins that destroys pathogenic organisms. Studies have shown that levels of acute phase proteins are increased in otherwise healthy adults with poor periodontal status. This article highlights about the synthesis, structure, types and function of acute phase proteins and the associated relation of acute phase proteins in Periodontitis.

Evaluation of gingival crevicular fluid levels of tissue plasminogen activator, plasminogen activator inhibitor 2, matrix metalloproteinase-3 and interleukin 1-β in patients with different periodontal diseases

OBJECTIVES

The purpose of this study was to evaluate the gingival crevicular fluid levels of interleukin-1beta (IL-1β), matrix metalloproteinases-3 (MMP-3), tissue type plasminogen activator (t-PA) and plasminogen activator inhibitor 2 (PAI-2) in patients with chronic periodontitis, aggressive periodontitis (AgP) and healthy individuals (controls).

MATERIAL AND METHODS

Systemically healthy (21 chronic periodontitis, 23 AgP and 20 controls) subjects were included in this study. Plaque index, gingival index, probing pocket depth and clinical attachment level were recorded and gingival crevicular fluid samples were collected. Assays for IL-1β, MMP-3, t-PA and PAI-2 levels in gingival crevicular fluid were carried out by an enzyme-linked immunosorbent assay. The one-sample Kolmogorov-Smirnov test, Mann-Whitney U test and Spearman correlation coefficient were used for data analyses.

RESULTS

Gingival crevicular fluid levels of t-PA and IL-1β were significantly higher in chronic periodontitis and AgP groups than in the control group (p < 0.001). MMP-3 levels in gingival crevicular fluid were detected as significantly higher in the chronic periodontitis and AgP groups compared with the control group (p < 0.05). The t-PA/PAI-2 rate of patients with chronic periodontitis and AgP were significantly higher than the control group (p < 0.05). The positive correlations were found among the PAI-2, t-PA, IL-1β and MMP-3 levels in gingival crevicular fluid. The volume of the gingival crevicular fluid correlated with all of the clinical parameters (p < 0.001). There were positive correlations between the gingival crevicular fluid levels of PAI-2 and the probing pocket depth and between gingival crevicular fluid levels of PAI-2 and the clinical attachment level (p < 0.01). Similarly, significant correlations were found between t-PA levels and probing pocket depth and between t-PA levels and clinical attachment level measurements (p < 0.001).

CONCLUSION

The present data showed that gingival crevicular fluid levels of IL-1 β, MMP-3 and t-PA increased in periodontal disease regardless of the periodontitis type and played a part in tissue destruction.

The plasminogen activation system in periodontal tissue (Review)

The plasminogen activation system (PAS) plays an essential role in tissue proteolysis in physiological and pathological processes. Periodontitis is a chronic infection associated with increased proteolysis driven by plasminogen activation. In this comprehensive review, we summarise the effects of PAS in wound healing, tissue remodelling, inflammation, bacterial infection, and in the initiation and progression of periodontal disease. Specifically, we discuss the role of plasminogen activators (PAs), including urokinase PA (uPA), tissue-type PA (tPA), PA inhibitor type 1 (PAI-1) and 2 (PAI-2) and activated plasminogen in periodontal tissue, where their concentrations can reach much higher values than those found in other parts of the body. We also discuss whether PA deficiencies can have effects on periodontal tissue. We conclude that in periodontal disease, PAS is unbalanced and equalizing its function can improve the clinical periodontal tissue condition.

Detection of suPAR in the Saliva of Healthy Young Adults: Comparison with Plasma Levels

The soluble urokinase plasminogen activator receptor (suPAR) has been detected in blood, plasma, serum, urine, ovarian cystic fluid, and cerebrospinal fluid. Elevated suPAR levels in plasma have been associated with negative outcomes in various diseases, such as bacteremia, sepsis, SIRS, cardiovascular disease, cancer, and tuberculosis. The primary aim of this study was to investigate whether suPAR can be detected in saliva from healthy individuals and thus, if saliva suPAR can be related to plasma suPAR, CRP, BMI, or gender. Blood and unstimulated whole saliva was collected from 20 healthy individuals (10 female and 10 male, median age of 28 years; range 21–41). CRP and suPAR were measured with ELISA in saliva and serum/plasma. suPAR was detected in all saliva samples in the 5.2–28.1 ng/mL range, with a median value of 17.1 ng/mL. Saliva suPAR was significantly higher (P < 0.001) but not correlated to plasma suPAR in healthy young adults with normal plasma suPAR levels. suPAR and CRP levels were correlated in blood but not in saliva. No correlation was found between BMI, age, or gender and suPAR in saliva.

Host-derived diagnostic markers related to soft tissue destruction and bone degradation in periodontitis

BACKGROUND

A major challenge in clinical periodontics is to find a reliable molecular marker of periodontal tissue destruction with high sensitivity, specificity and utility.

OBJECTIVES

The aim of this systematic review is to evaluate available literature on 'the utility of molecular markers of soft and hard periodontal tissue destruction'.

MATERIALS AND METHODS

Based on the focused question, 'What is the utility of molecular markers of soft and hard periodontal tissue destruction', an electronic and manual search was conducted for human studies presenting clinical data for the potential of molecular markers of tissue destruction in biofluids; gingival crevicular fluid (GCF), saliva, and serum.

RESULTS

Papers fulfilling the inclusion criteria were selected. All relevant data from the selected papers were extracted and recorded in separate tables for molecules in GCF, saliva, and serum.

CONCLUSION

Within the defined limits of the Problem/Population, Intervention, Comparison, Outcome, the present analysis reveals that (a) no single or combination of markers exists that can disclose periodontal tissue destruction adequately; (b) while the most fruitful source of biomarkers for periodontal destruction appears to be in molecules tightly related to bone and soft tissue destruction, this remains to be objectively demonstrated. Currently, clinical measurements are still the most reliable.

Prevotella intermedia stimulates tissue-type plasminogen activator and plasminogen activator inhibitor-2 expression via multiple signaling pathways in human periodontal ligament cells

Prevotella intermedia is an important periodontal pathogen that induces various inflammatory and immune responses. In this study, we investigated the effects of P. intermedia on the plasminogen system in human periodontal ligament (hPDL) cells and explored the signaling pathways involved. Using semi-quantitative reverse transcription (RT)-PCR and quantitative real-time RT-qPCR, we demonstrated that P. intermedia challenge increased tissue-type plasminogen activator (tPA) and plasminogen activator inhibitor (PAI)-2 expression in a concentration- and time-dependent manner, but exerted no influence on urokinase-type plasminogen activator and PAI-1mRNA expression in hPDL cells. Prevotella intermedia stimulation also enhanced tPA protein secretion as confirmed by enzyme-linked immunosorbent assay. Western blot results revealed that P. intermedia treatment increased phosphorylation of extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK) and p38 kinase (p38). ERK, JNK and protein kinase C inhibitors significantly attenuated the P. intermedia-induced tPA and PAI-2 expression. Furthermore, p38 and phosphatidylinositol 3-kinase inhibitors markedly decreased PAI-2 expression, whereas they showed no or little inhibition on tPA expression. In contrast, inhibition of protein kinase A greatly enhanced the upregulatory effect of P. intermedia on tPA and PAI-2 expression. Our results suggest that P. intermedia may contribute to periodontal tissue destruction by upregulating tPA and PAI-2 expression in hPDL cells via multiple signaling pathways.

Gingival crevicular fluid IL-6, tPA, PAI-2, albumin levels following initial periodontal treatment in chronic periodontitis patients with or without type 2 diabetes

OBJECTIVES

To evaluate initial periodontal treatment effects on gingival crevicular fluid (GCF) interleukin-6 (IL-6), tissue-type plasminogen activator (tPA), plasminogen activator inhibitor-2 (PAI-2), albumin levels in type 2 diabetic patients.

DESIGN AND METHODS

GCF samples were collected from 20 type 2 diabetic, 22 non-diabetic non-smokers all with chronic periodontitis at baseline, 1-, 3-months following initial periodontal treatment. Biochemical analysis was performed by ELISA. Data were tested by Mann-Whitney U, Wilcoxon tests.

RESULTS

The total amounts of albumin, IL-6, tPA, PAI-2 decreased significantly in diabetics after treatment (1- and 3-months) whereas, only PAI-2 decreased in non-diabetic group at 3-months (p < 0.05). There were statistically significant differences between the diabetics and non-diabetics at all time points for albumin, PAI-2 and at 1-, 3-months for GCF volume (p < 0.050) but only at baseline for IL-6 (p < 0.050).

CONCLUSION

Present data suggest clinical improvements are less apparent in diabetic chronic periodontitis patients as reflected by disease markers in GCF and by an increase in concentrations of inflammatory proteins IL-6, tPA, and PAI-2 in GCF of this patient group following initial periodontal treatment.

Effects of human aging on periodontal tissues

Loss of teeth is frequently associated with periodontal disease in older adults. The aim of this review was to present the effects of aging on the periodontal tissues. Aging alone does not lead to critical loss of periodontal attachment in healthy elderly persons. The effects of aging on periodontal tissues are based on molecular changes in the periodontal cells, which intensify bone loss in elderly patients with periodontitis. These effects may be associated with (1) alterations in differentiation and proliferation of osteoblasts and osteoclasts; (2) an increase in periodontal cell response to the oral microbiota and mechanical stress leading to the secretion of cytokines involved in osseous resorption; and (3) systemic endocrine alterations in the elderly people.

Gene expression in periodontal tissues following treatment

BACKGROUND

In periodontitis, treatment aimed at controlling the periodontal biofilm infection results in a resolution of the clinical and histological signs of inflammation. Although the cell types found in periodontal tissues following treatment have been well described, information on gene expression is limited to few candidate genes. Therefore, the aim of the study was to determine the expression profiles of immune and inflammatory genes in periodontal tissues from sites with severe chronic periodontitis following periodontal therapy in order to identify genes involved in tissue homeostasis.Gingival biopsies from 12 patients with severe chronic periodontitis were taken six to eight weeks following non-surgical periodontal therapy, and from 11 healthy controls. As internal standard, RNA of an immortalized human keratinocyte line (HaCaT) was used. Total RNA was subjected to gene expression profiling using a commercially available microarray system focusing on inflammation-related genes. Post-hoc confirmation of selected genes was done by Realtime-PCR.

RESULTS

Out of the 136 genes analyzed, the 5% most strongly expressed genes compared to healthy controls were Interleukin-12A (IL-12A), Versican (CSPG-2), Matrixmetalloproteinase-1 (MMP-1), Down syndrome critical region protein-1 (DSCR-1), Macrophage inflammatory protein-2beta (Cxcl-3), Inhibitor of apoptosis protein-1 (BIRC-1), Cluster of differentiation antigen 38 (CD38), Regulator of G-protein signalling-1 (RGS-1), and Finkel-Biskis-Jinkins murine osteosarcoma virus oncogene (C-FOS); the 5% least strongly expressed genes were Receptor-interacting Serine/Threonine Kinase-2 (RIP-2), Complement component 3 (C3), Prostaglandin-endoperoxide synthase-2 (COX-2), Interleukin-8 (IL-8), Endothelin-1 (EDN-1), Plasminogen activator inhibitor type-2 (PAI-2), Matrix-metalloproteinase-14 (MMP-14), and Interferon regulating factor-7 (IRF-7).

CONCLUSION

Gene expression profiles found in periodontal tissues following therapy indicate activation of pathways that regulate tissue damage and repair.

Gingival crevicular fluid PGE2, IL-1beta, t-PA, PAI-2 levels in type 2 diabetes and relationship with periodontal disease

OBJECTIVES

To evaluate if type 2 diabetes mellitus increase gingival crevicular fluid (GCF) levels of prostaglandin E(2) (PGE(2)), interleukin-1beta (IL-1beta), tissue-type plasminogen activator (t-PA), and plasminogen activator inhibitor-2 (PAI-2).

DESIGN AND METHODS

Seventeen type 2 diabetic patients with periodontal disease (DM), 17 otherwise healthy periodontally diseased patients (PD) and 17 systemically and periodontally healthy control subjects (H) were enrolled. Clinical periodontal measurements were recorded at six sites/tooth. GCF samples were analyzed by ELISA. Data were tested by statistical tests.

RESULTS

DM group revealed lower IL-1beta levels than PD group (p<0.01). PGE(2), t-PA and PAI-2 levels were similar in DM and PD groups (p>0.05). PGE(2), t-PA levels were higher in DM and PD groups than H group (p<0.05). PAI-2 level was higher in DM group than H group (p<0.05). GCF total amount of PGE(2) in DM group exhibited significant correlations with all clinical periodontal measurements (p<0.05).

CONCLUSION

Type 2 diabetes in this study seems not to increase GCF levels of the evaluated inflammatory mediators.

Isolation and characterization of human gingival microvascular endothelial cells

BACKGROUND AND OBJECTIVE

Endothelial cells have a substantial role in maintaining vascular homeostasis, and their dysregulation can contribute to the development of pathology. The plasminogen activators and their inhibitors may, arguably, be the single most important proteolytic system of the endothelium for vascular maintenance by controlling plasminogen activation and other proteolytic cascades that impact on clotting, hemodynamics, angiogenesis and the character of the vascular wall. In chronic periodontal disease, significant changes to the microvasculature occur in association with the severity of the disease. Investigation of the role played by endothelial cells in periodontal health and disease has been limited to in situ immunolocalization or to the use of endothelial cells of nongingival origin, such as human umbilical vein endothelial cells. The objective of this research was to establish a replicable protocol for isolating microvascular endothelial cells from the gingiva.

MATERIAL AND METHODS

From inflamed gingiva, isolated cells were characterized by morphology, the expression of factor VIII-related antigen, the expression of UEA-1 ligand, the uptake of acetylated low-density lipoprotein, network formation on Matrigel, and by the expression levels of urokinase plasminogen activator, tissue plasminogen activator, plasminogen activator inhibitor-1 and collagen IV.

RESULTS AND CONCLUSION

Gingival endothelial cells were most readily obtained from inflamed gingival tissues, and these endothelial cells, when isolated by the protocol established herein, demonstrated endothelial characteristics and constitutively secreted plasminogen activators and plasminogen activator inhibitor-1 in culture.

Plasminogen activation by fibroblasts from periodontal ligament and gingiva is not directly affected by chemokines in vitro

OBJECTIVE

Chronic inflammation in periodontal disease is associated with increased plasminogen activation and elevated levels of chemokines. It is unknown whether chemokines can regulate the activation of plasminogen via modulation of plasminogen activators (PA) and the corresponding plasminogen activator inhibitors (PAI) in periodontal tissue.

DESIGN

To establish a link between chemokines and activation of plasminogen, human periodontal ligament fibroblasts (PDL) and gingival fibroblasts (GF) were incubated with IL-8, monocyte chemoattractant protein-1, macrophage inflammatory protein-1alpha, and platelet factor-4, either alone or in the presence of the inflammatory mediators TGF-beta and IL-1. The potential of the cell lysates to activate plasminogen was based on kinetic studies with the substrate casein. Casein zymography was performed to determine the molecular sizes of the PA. Total PAI-1 in the cell-conditioned medium was quantified by immunoassay.

RESULTS

We report that the chemokines did not affect activation of plasminogen by PDL and GF. Even in the presence of TGF-beta which suppressed, and IL-1 which stimulated plasminogen activation, the chemokines had no direct effect. Inhibition of PA and plasmin, but not of matrix metalloproteinases and cysteine proteinases prevented caseinolysis. The plasminogen activation capacity of the cell lysates was represented by a single band with features of uPA. The immunoassay showed that the release of PAI-1 in PDL and GF remained unaffected by the chemokines, also when stimulated with TGF-beta.

CONCLUSIONS

These results suggest that plasminogen activation by PDL and GF is not directly affected by the chemokines even in the presence of the inflammatory mediators TGF-beta and IL-1.

Associations between peri-implant crevicular fluid volume, concentrations of crevicular inflammatory mediators, and composite IL-1A ?889 and IL-1B +3954 genotype: A cross-sectional study on implant recall patients with and without clinical signs of peri-implantitis

OBJECTIVES

To assess possible relationships between peri-implant crevicular fluid (PICF) volumes, biochemical markers of the peri-implant immune response, and periodontitis-associated genotype.

MATERIAL AND METHODS

PICF samples from 29 implant maintenance patients, 24 wearing overdentures, five having single crowns and bridgework (11 patients with peri-implantitis and 18 individuals with healthy peri-implant conditions), were analyzed for per site and per crevicular-fluid-volume concentrations of interleukin-1beta, plasminogen activator inhibitor type 2, and prostaglandin E2 by ELISA. Associations between the three substance concentrations and to crevicular fluid flow rate were analyzed by linear regression analysis. The possible differentiating influence of the composite interleukin-1A and -1B genotype on the patients' peri-implant health and biochemical inflammatory status was checked formally with t-test statistics and the Wilcoxon' test. One implant per patient was chosen for analysis.

RESULTS

In patients with healthy peri-implant conditions, genotype-positive individuals showed elevated crevicular fluid flow rates and at the same time reduced mediator concentrations. In patients with an implant affected from peri-implantitis, no statistically significant influence of the periodontitis-associated genotype around the fixture can be stated. There was no statistical difference between per site and per crevicular-fluid-volume concentration analyses. All three mediator concentrations were positively related to each other, while there was a strong negative correlation between crevicular fluid volume and plasminogen activator inhibitor 2 or prostaglandin E2.

CONCLUSIONS

The Interleukin-1 polymorphism investigated exerted only little influence on the peri-implant crevicular immune response, and this influence appeared to be of limited impact in sites with established peri-implantitis lesions.

Gene polymorphisms of tissue plasminogen activator and plasminogen activator inhibitor-1 in Turkish patients with generalized aggressive periodontitis

AIM

Tissue plasminogen activator (t-PA) and plasminogen activator inhibitor-1 (PAI-1) have important roles in proteolytic events in periodontitis. The aim of this study was to investigate TPA and PAI-1 gene polymorphisms in relation to susceptibility to generalized aggressive periodontitis (G-AgP).

METHODS

Genomic DNA was obtained from peripheral blood of 90 G-AgP patients and 154 periodontally healthy subjects. 4G/5G polymorphism in the promoter region of the PAI-1 gene and Alu-repeat insertion/deletion (I/D) polymorphism in intron 8 of the TPA gene were genotyped by polymerase chain reaction and endonuclease digestion.

RESULTS

The genotype distributions of TPA and PAI-1 genes were similar between G-AgP and healthy subjects (p>0.05). The distribution of TPA genotypes in G-AgP patients was 33.4% D/D, 44.4% I/D, and 22.2% I/I and was 26.3% D/D, 40.4% I/D, and 33.3% I/I in healthy subjects. The D allele was 55.6% in G-AgP and 46.6% in healthy subjects. There was a significant difference among study groups in D allele frequencies (p=0.044). The PAI-1 genotype distribution in G-AgP was 29.1% 4G/4G, 43.0% 4G/5G, and 27.9% 5G/5G, while it was 35.7% 4G/4G, 43.8% 4G/5G, and 20.5% 5G/5G in healthy subjects.

CONCLUSION

These data suggest that the D polymorphic allele of TPA gene polymorphism could be associated with susceptibility to G-AgP in Turkish subjects.

Actinobacillus actinomycetemcomitans lipopolysaccharide regulates matrix metalloproteinase, tissue inhibitors of matrix metalloproteinase, and plasminogen activator production by human gingival fibroblasts: A potential role in connective tissue destructio

Fibroblasts, a major constituent of gingival connective tissue, can produce immunoregulatory cytokines and proteolytic enzymes that may contribute to tissue destruction. In this study, we evaluated the production of matrix metalloproteinases (MMPs), tissue inhibitors of MMPs (TIMPs), and plasminogen activators by gingival fibroblasts stimulated with lipopolysaccharides (LPS) produced by periodontopathogens, including Actinobacillus actinomycetemcomitans. In addition, changes in the expression and phosphorylation state of fibroblast intracellular signaling proteins induced by A. actinomycetemcomitans LPS were characterized using antibody microarrays. We showed that A. actinomycetemcomitans LPS induced the production of a 50 kDa plasminogen activator, MMP-2 and, to a lesser extent, MMP-3 by fibroblasts. The stimulation of fibroblasts with A. actinomycetemcomitans LPS also resulted in the overproduction of TIMP-1, but had no effect on the production of TIMP-2. Comparable responses were also obtained with Porphyromonas gingivalis and Fusobacterium nucleatum subsp. nucleatum LPS. The results of the microarray analyses showed that A. actinomycetemcomitans LPS induced changes in the phosphorylation state and expression of gingival fibroblast intracellular signaling proteins. More specifically, they suggested that A. actinomycetemcomitans LPS may induce both Jun N-terminus protein-serine kinases (JNK) and mitogen-activated protein-serine kinase p38 alpha (p38alpha MAPK) pathway activation, leading to increased activator protein-1 (AP-1) and nuclear factor kappa-B (NFkappaB) activities, which in turn can stimulate MMP-2, MMP-3, TIMP-1, and urokinase-type plasminogen activator (uPA) expression. This may contribute to periodontal connective tissue destruction.

Evaluation of t-PA, PAI-2, IL-1βand PGE2in gingival crevicular fluid of rheumatoid arthritis patients with periodontal disease

AIMS

This study was undertaken to compare periodontal conditions, gingival crevicular fluid (GCF) levels of tissue-type plasminogen activator (t-PA), its inhibitor plasminogen activator inhibitor-2 (PAI-2), interleukin-1beta (IL-1beta), prostaglandin E(2) (PGE(2)) in rheumatoid arthritis (RA) patients and control groups.

METHODS

Twenty-three RA patients, 17 systemically healthy patients with periodontal disease (PD), and 17 systemically and periodontally healthy subjects were recruited. GCF samples were obtained from two single-rooted teeth. Full-mouth clinical periodontal measurements were recorded at six sites/tooth. GCF samples were analysed using relevant ELISA kits. Data were tested statistically by appropriate tests.

RESULTS

Total amounts of t-PA, PAI-2 and PGE(2) in GCF samples of the healthy control group were significantly lower than the other groups (p<0.05). The RA group exhibited a higher total amount of t-PA in GCF samples than the PD group (p<0.05). PAI-2, IL-1beta and PGE(2) total amounts were similar in RA and PD groups (p>0.05).

CONCLUSION

The coexistence of RA and periodontitis does not seem to affect clinical periodontal findings or systemic markers of RA. Similar inflammatory mediator levels in RA and PD groups, despite the long-term usage of corticosteroids, non-steroidal anti-inflammatory drugs, suggest that RA patients may have a propensity to overproduce these inflammatory mediators.

A clinical study of plasminogen activator activity in gingival tissue in dogs with gingivitis and periodontitis

The aim of the present study was to evaluate plasminogen activator activity (PAA), tissue-type plasminogen activator (t-PA) antigen level and plasminogen activator inhibitor-1 (PAI-1) antigen in normal canine gingival tissue samples, gingivitis as well as in different stages of periodontal disease. Gingival tissue from 141 adult dogs were analysed spectrophotometrically in order to determine PAA. The tissues were also examined histopathologically. The Sulcus Bleeding Index was used to evaluate the active and inactive phase of periodontal disease. T-PA antigen as well as PAI-1 antigen level was measured by ELISA. There was a significant increase of PAA and t-PA antigen in samples from inflamed gingival tissue compared with normal gingival tissue, while PAI-1 antigen was not detected in either normal or inflamed gingiva. As the severity of periodontal disease was increasing, PAA and t-PA antigen values were significantly higher in periodontitis tissue sample groups, according to the pattern: gingivitis<early periodontitis<moderate periodontitis<severe periodontitis (P<0.001). PAA and t-PA antigen were increased in samples from the inflamed gingival tissue with higher Bleeding Index, (heavy bleeding>moderate bleeding>slight bleeding, P<0.001). In conclusion, this study indicates that PAA and t-PA antigen level may be used to evaluate the evolution of periodontal disease in dog.

Periodontitis in humans and non-human primates: oral-systemic linkage inducing acute phase proteins

BACKGROUND

The acute phase response (APR) represents a systemic counterpart to the localized inflammatory response. This report describes patient-oriented and non-human primate model studies to determine the effect of periodontal disease on systemic acute phase proteins (APP).

METHODS

Patient-oriented studies included comparison of the levels of APP, using enzyme-linked immunosorbent assay (ELISA), with the presence and severity of periodontitis in localized chronic periodontitis (LCP), generalized aggressive periodontitis (GAP), and Sjogren's syndrome (SS) patients. The non-human primate experiments evaluated the serum level of APPs under natural conditions, following mechanical hygiene, experimental gingivitis, and during ligature-induced periodontitis.

RESULTS

Analysis of the LCP population showed what appeared to be a threshold of periodontal disease severity required for elevating the C-reactive protein (CRP) and haptoglobin (HG). The results demonstrated a significant elevation in CRP in the GAP versus the control groups, as well as lower levels of all mediators in healthy non-smokers (HNS) versus smokers (HS), suggesting that these systemic inflammatory markers were altered in response to challenge by noxious materials from smoking. Significantly different levels of CRP, HG, and alpha1-antiproteinase were noted in the SS patients suggesting that the autoimmune aspects of Sjögren's syndrome may impact upon oral health and systemic responses. Parallel evidence was also obtained from the primate studies. Providing mechanical oral hygiene, which significantly lowered clinical inflammation and bleeding of the gingiva, decreased the serum APP levels. Both CRP and fibrinogen were significantly elevated during progressing periodontitis, which also appeared to have an impact on serum lipids and lipoproteins.

CONCLUSIONS

These findings supported results relating chronic oral infections and the inflammation of periodontitis as contributors to and/or triggers for systemic inflammatory responses. Finally, similarities in the clinical and microbiological parameters of gingival inflammation and periodontitis between humans and non-human primates was extended to identification of changes in serum APP in the non-human primates that appeared to be in direct response to the induction of progressing periodontitis. These systemic changes provide additional evidence for the biological plausibility of periodontal infections contributing to various systemic diseases.

Plasminogen activator system in smokers and non-smokers with and without periodontal disease

BACKGROUND

The present study assessed levels of plasminogen activator (PA) system proteins in gingival crevicular fluid (GCF) and serum of chronic gingivitis, chronic periodontitis patients and periodontally healthy subjects and evaluated how smoking influenced these levels.

METHODS

Twenty chronic gingivitis; 20 chronic periodontitis patients and 20 periodontally healthy volunteers were consecutively recruited according to the inclusion criteria so that exactly half of the subjects in each category were smokers. GCF samples from four sites together with serum samples were obtained from each subject. GCF levels of tissue type PA (t-PA), urokinase type PA (u-PA), PA inhibitor-1 (PAI-1) and PA inhibitor-2 (PAI-2) and serum concentrations of cotinine, u-PA and PAI-1 were analysed by enzyme-linked immunosorbent assay.

RESULTS

The only statistically significant difference between smokers and non-smokers was a lower GCF PAI-2 concentrations in healthy smokers compared with healthy non-smokers (p<0.01). Gingivitis and periodontitis patients had higher GCF concentrations of PAI-2 than healthy subjects (p<0.002 and p<0.02 respectively). The ratio of u-PA:PAI-1 and t-PA:PAI-1 were significantly higher in GCF of smokers with periodontitis compared with "healthy" smokers, whereas the ratio of t-PA:PAI-2 was significantly lower in smokers with periodontal disease (p<0.05).

CONCLUSIONS

GCF levels of the PA system proteins are increased in chronic gingivitis and periodontitis compared with healthy gingiva. Smoking had only subtle effects on the GCF PA system proteins with the exception of PAI-2, and the balance of activators and inhibitors. These findings suggest one mechanism whereby smoking may exert detrimental effects on the periodontal tissues.

Plasminogen activators and plasminogen activator inhibitors in gingival crevicular fluid of cyclosporin A-treated patients

BACKGROUND

The plasminogen activator (PA) system plays many roles in the inflammatory process and tissue remodelling and repair and is considered to play a significant role in periodontal tissue destruction and healing. The aim of this study was to evaluate the role of the PA system in cyclosporin A (CsA)-induced gingival overgrowth in renal transplant patients.

METHODS

Eighteen renal transplant patients exhibiting moderate to severe CsA-induced gingival overgrowth, 10 other renal transplant patients receiving CsA therapy but showing no sign of CsA-induced gingival overgrowth (CsA-H), 16 chronic gingivitis patients (CG) and 16 systemically and periodontally healthy control subjects (H) were included in the study. Gingival crevicular fluid (GCF) samples were obtained from four randomly selected sites in each subject with the exception of the CsA-induced gingival overgrowth group, where four GCF samples were harvested from sites with severe overgrowth (CsA GO+) and from four sites without any gingival overgrowth (CsA GO-). The GCF levels of albumin, tissue-type plasminogen activator (t-PA), urokinase-type plasminogen activator (u-PA), plasminogen activator inhibitor 1 (PAI-1) and plasminogen activator inhibitor 2 (PAI-2) were analysed by enzyme-linked immunosorbent assay. The results were tested for statistical differences.

RESULTS

In CsA GO+ sites t-PA levels were significantly elevated in comparison with gingivitis and healthy sites, while PAI-2 levels in these sites showed statistically significant differences only with CsA-H and gingivitis sites (p<0.05). The levels of t-PA and PAI-2 were significantly higher in CsA GO- sites compared with those of CsA-H, gingivitis and healthy sites (p<0.05). The levels of u-PA and PAI-1 failed to show significant differences between the study groups.

CONCLUSIONS

The findings of the present study indicate alterations in GCF t-PA and PAI-2 levels in CsA-induced gingival overgrowth and might suggest involvement of the plasminogen activating system in the pathogenesis of this side-effect of CsA therapy. However, to what extent these molecules contribute to the pathogenesis of CsA-induced gingival overgrowth remains to be determined.

Periodontal host modulation with antiproteinase, anti-inflammatory, and bone-sparing agents. A systematic review

BACKGROUND

The use of modulating agents, including inhibition of matrix metalloproteinases (MMPs) with antiproteinases, blocking production of proinflammatory cytokines and prostaglandins with anti-inflammatory drugs, and inhibiting activation of osteoclasts with bone-sparing agents, has been postulated to be of therapeutic value as an adjunctive therapy to the management of chronic periodontitis.

RATIONALE

The objective of this systematic review of the literature was to assess the adjunctive efficacy of antiproteinase, anti-inflammatory, and bone-sparing host-modulating agents in the treatment of gingivitis, aggressive periodontitis, and chronic periodontitis. FOCUSED QUESTIONS: 1. In patients with periodontal diseases, what is the effect of host-modulation agents, alone or combined with conventional therapy, compared to conventional therapy alone as assessed by clinical, radiographic, adverse, and patient-centered outcomes? 2. In patients with dental implants, what is the effect of host-modulation agents on implant success assessed by clinical, radiographic, adverse, and patient-centered outcomes?

SEARCH PROTOCOL

MEDLINE, Embase, and the Cochrane Library databases were searched without language restrictions through April 1, 2002 for studies that used tetracycline (TET)-related matrix metalloproteinase (MMP) inhibitors, or non-steroidal anti-inflammatory drugs (NSAIDs) and bisphosphonate anti-osteolytic agents. The investigation also included hand searching of journals and contacting authors and industry experts.

SELECTION CRITERIA

INCLUSION CRITERIA

Only human studies (randomized controlled clinical trials, cohort studies, case-control studies, cross-sectional studies, and case series) were selected. Studies were on subjects with gingivitis, aggressive or chronic periodontitis, or dental implants. Interventions included TET-related MMP inhibitors, NSAIDs, or bisphosphonate anti-osteolytic agents.

EXCLUSION CRITERIA

Studies that used MMP tissue inhibitors as diagnostic or prognostic indicators of periodontal disease or that evaluated short-term systemic antibodies or locally delivered levels of drugs with antiproteinase activity were excluded.

DATA COLLECTION AND ANALYSIS

The primary outcomes for assessment were changes in bone or clinical attachment levels (CAL); secondary outcomes included clinical measures of plaque, gingival inflammation, probing depth (PD), and mobility. Summary data appropriate for meta-analysis were pooled using a weighted average and analyzed using a standardized difference; the results were checked with both fixed-effects and random-effects models.

MAIN RESULTS

1. A meta-analysis done on the studies reporting changes in CAL and PD following administration of sub-antimicrobial doses of doxycycline (SDD) in conjunction with scaling and root planing (SRP) in patients with periodontitis showed a statistically significant beneficial adjunctive effect. 2. There were insufficient data to provide meta-analyses on periodontal patients treated with other host-modulating agents; descriptive tables are included. 3. NSAIDS show promise in their ability to slow periodontal disease. 4. Preliminary data on bisphosphonate agents indicate there is a potential role for these agents in periodontitis management. 5. There are a very limited number of studies on host-modulating agents and dental implants and no analyses were possible. 6. Because the treatment methodologies and clinical variables differed considerably among the studies, it is difficult to summarize the information and identify a reliable total patient population.

REVIEWERS' CONCLUSIONS

1. Large multi-center trials are needed to evaluate the role of host-modulating agents in the treatment of periodontitis. 2. NSAIDS and bisphosphonate drugs may have a potential adjunctive role in periodontal therapy. 3. The adjunctive use of SDD with SRP is statistically more effective than SRP alone in reducing PD and in achieving CAL gain.

Reduced gingival fluid flow: a peripheral marker of the pharmacological effect of roquinimex

OBJECTIVE

Roquinimex is a drug with effects on inflammation and tumors. The pharmacological effect is not fully understood, and the molecular mechanism most characterized in vitro is an increase of plasminogen activator inhibitor type 2 (PAI-2) in human peripheral blood monocytes. The aims were to investigate peripheral pharmacological effects of roquinimex on peripheral blood monocytes and dog gingival fluid (GCF).

DESIGN

Six dogs were used in a cross-over study. The amount of GCF was determined with a Periotron. The PAI-2 concentration in GCF was determined with ELISA. Monocytes were isolated from peripheral blood.

RESULTS

Dogs treated with the drug had significantly lower GCF flow values and the PAI-2 concentration in GCF was higher, but no effect was seen on peripheral monocytes.

CONCLUSION

Roquinimex treatment led to a consistently decreased flow rate of GCF and a higher local concentration of PAI-2 in GCF.

Plasminogen-activator-inhibitor-1 promoter polymorphism as a risk factor for adult periodontitis in non-smokers

Periodontal diseases belong to the most common chronic disorders affecting mankind. Smoking and impaired plasminogen activation with hypercoagulation and fibrinolysis inhibition have been proposed as having a role in predisposition to these diseases. We investigated relationships among adult periodontitis, smoking, and a variation in the deletion/insertion (4G/5G) promoter polymorphism of the plasminogen-activator-inhibitor-1 (PAI-1) gene in 304 Caucasian subjects. An association was detected between the deletion (4G) allele (and 4G/4G genotype) and periodontitis (P = 0.0022, P(corr) < 0.01; P = 0.014, P(corr) < 0.05). A stronger association occurred in non-smokers (P = 0.00021, P(corr) < 0.01; P = 0.0024, P(corr) < 0.05) where the presence of the PAI-1 gene 4G allele appears to be one of the risk factors for periodontitis.

The plasminogen activating system in periodontal health and disease

The plasminogen activating system is important for extracellular proteolysis and plays a regulatory role in interactions with other tissue degrading systems. Studies on the plasminogen activating system in gingival crevicular fluid (GCF) as well as gingival tissue are reviewed. t-PA, u-PA, PAI-1 and PAI-2 have all been detected in GCF. Especially t-PA and PAI-2 are found in high concentrations. In tissue studies fibrinolytic activity has been found in the gingival pocket epithelium in humans and in animal studies. t-PA and PAI-2 have been detected there immunohistochemically. Local production of the PAs and PAls has been verified with in situ hybridization. In inflammation, a more intense and widespread immunohistochemical staining of t-PA and PAI-2 is seen. Higher concentrations of t-PA and PAI-2 are found in GCF but the balance between them seems to be constant. A systemically disturbed balance of the plasminogen activating system in GCF has been observed during pregnancy, with a possible protective function of PAI-2. In studies of periodontitis, the production of PAI-2 seemed to be locally lowered at impaired sites. In a study of children, a higher inflammatory response to bacterial plaque was accompanied by a higher fibrinolytic ativity in GCF samples. Bacterial LPS has been found to change the ratio of t-PA to PAI-2 in cultured gingival fibroblasts. Interactions between PAI-2 and a protease in the gingival epithelium has been verified through the immunohistochemical detection of relaxed PAI-2.

The expression of plasminogen activator system in a rat model of periodontal wound healing

BACKGROUND

The plasminogen activator system has been proposed to play a role in proteolytic degradation of extracellular matrices in tissue remodeling, including wound healing. The aim of this study was to elucidate the presence of components of the plasminogen activator system during different stages of periodontal wound healing.

METHODS

Periodontal wounds were created around the molars of adult rats and healing was followed for 28 days. Immunohistochemical analyses of the healing tissues and an analysis of the periodontal wound healing fluid by ELISA were carried out for the detection of tissue-type plasminogen activator (t-PA), urokinase-type plasminogen activator (u-PA), and 2 plasminogen activator inhibitors (PAI-1 and PAI-2).

RESULTS

During the early stages (days 1 to 3) of periodontal wound healing, PAI-1 and PAI-2 were found to be closely associated with the deposition of a fibrin clot in the gingival sulcus. These components were strongly associated with the infiltrating inflammatory cells around the fibrin clot. During days 3 to 7, u-PA, PAI-1, and PAI-2 were associated with cells (particularly monocytes/macrophages, fibroblasts, and endothelial cells) in the newly formed granulation tissue. During days 7 to 14, a new attachment apparatus was formed during which PAI-1, PAI-2, and u-PA were localized in both periodontal ligament fibroblasts (PDL) and epithelial cells at sites where these cells were attaching to the root surface. In the periodontal wound healing fluid, the concentration for t-PA increased and peaked during the first week. PAI-2 had a similar expression to t-PA, but at a lower level over the entire wound-healing period.

CONCLUSIONS

These findings indicate that the plasminogen activator system is involved in the entire process of periodontal wound healing, in particular with the formation of fibrin matrix on the root surface and its replacement by granulation tissue, as well as the subsequent formation of the attachment of soft tissue to the root surface during the later stages of wound repair.