Expression Levels of Matrix Metalloproteinase-9 and Gram-negative Bacteria in Symptomatic and Asymptomatic Periapical Lesions

Local immunomodulatory effects of intracanal medications in apical periodontitis

The immune system is an extremely complex biological network that plays a crucial role in the hemostasis of periapical tissue, pathogenesis of apical periodontitis (AP) as well as periapical tissue healing. The successful elimination of microbial infections remains a significant challenge, mostly due to the ever-growing development of antimicrobial-resistant pathogens. The bacterial endurance in the root canal system contributes to features ranging from altered post-treatment healing to exacerbation of chronic periradicular immune response, that compromise the outcome of endodontic treatment. A highly effective strategy for combating infectious diseases and the associated inflammation-mediated tissue damage is to modulate the host immune response in conjunction with antimicrobial therapy. There are several medications currently used in endodontic treatment, however, they suffer various levels of microbial resistance and do not deliver all the required characteristics to simultaneously address both intracanal bacteria and periapical inflammation. Interaction of antimicrobial agents with the immune system can impact its function, leading to immune-suppressive or immune-stimulatory effects. The group of non-conventional antimicrobial medications, such as antimicrobial peptides, propolis, and nanomaterials, are agents that provide strong antimicrobial effectiveness and concomitant immunomodulatory and/or reparative effect, without any host tissue damages. Herein, we provide an overview of local immune modulation in AP and a comprehensive review of the immunomodulatory effect of antimicrobials intracanal medications applied in endodontics with specific emphasis on the antimicrobial nanomaterial-based approaches that provide immunomodulatory potential for successful clinical deployment in endodontics.

Baseline MMP expression in periapical granuloma and its relationship with periapical wound healing after surgical endodontic treatment

Background

Matrix metalloproteinases (MMPs) catalyzes the degradation of the extracellular matrix components and have a major role in many physiological processes including wound healing. In the current study, we examined the correlation of baseline MMPs 1, 2, 7, and 9 expressions with periapical wound healing after surgical endodontic treatment.

Methods

27 patients aged between 15 and 57 years presenting with chronic apical periodontitis or chronic apical abscess of an anterior tooth with previously attempted or failed root canal treatment were included in this study. During surgical endodontic treatment, tissue from the periapical lesion sample was collected and used for gross histopathological analysis as well as mRNA expression analysis of MMPs 1, 2, 7, and 9. Patients were recalled for follow-up after 6  months to evaluate the healing status both clinically and radiographically and healing was correlated with baseline MMP expression.

Results

Out of 27 patients, healing was observed in 15 patients at the end of 6 months, and in 21 patients after 12 months.. Six patients showed no healing even after 12 months. Analysis of baseline MMP 1, 2, 7, and 9 expression levels with healing status showed the mean relative expression of MMP2 and MMP9 to be considerably increased in the non-healing group as compared to the healing group.

Conclusion

Overexpression of MMP2 and MMP9 may be considered as a potential prognostic biomarker for periapical wound healing after surgical endodontic treatment. However, further studies are desirable to establish its precise relationship with periapical wound healing.

Clinical influence of calcium hydroxide intracanal medications on matrix metalloproteinases and tissue inhibitors of metalloproteinases in apical periodontitis

OBJECTIVES

This study investigated the influence of calcium hydroxide intracanal medications on the levels of metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) in apical periodontitis (AP).

MATERIALS AND METHODS

Twenty primarily infected root canals with AP were randomly divided into two groups: Ca(OH)₂ + sterile saline solution (SSL) group and Ca(OH)₂ + 2% chlorhexidine gel (CHX gel) group. We collected samples from the periradicular tissue fluid (PTF) before (s1) and after 14 days of intracanal medication (s2). MMP-1, MMP-2, MMP-9, TIMP-1, and TIMP-2 were measured by ELISA assay.

RESULTS

MMP-1, MMP-2, MMP-9, TIMP-1, and TIMP-2 were detected in all PTF samples at s1 and s2 (20/20). At s1, MMP-2 and MMP-9 were detected at higher levels than MMP-1 (p < .05). Higher levels of TIMP-1 than TIMP-2 were found in AP (p < .05). Additionally, we detected higher MMP-1, MMP-2, and MMP-9 over TIMP-1 and TIMP-2 levels in AP (p < .05). At s2, Ca(OH)₂ + SSL was as effective as Ca(OH)₂ + 2% CHX gel in lowering the levels of MMP-1, MMP-2, and MMP-9 after 14 days of intracanal medication, with no significant difference between them (p > .05). Both Ca(OH) ₂ intracanal medications had no significant impact on the levels of TIMP-1 and TIMP-2 (both p > .05). At s2, TIMP-1 levels were higher than TIMP-2 (p < .05). Moreover, there were positive correlations between the levels of MMP-1 and TIMP-1 and MMP-1 and TIMP-2 (p < .05).

CONCLUSIONS

Calcium hydroxide medications effectively lowered the levels of MMP-1, MMP-2, and MMP-9 in periapical tissues after 14 days of treatment, with no difference between them. Moreover, the calcium hydroxide intracanal medications tested here had no impact in TIMP-1 and TIMP-2 in periapical tissues.

CLINICAL RELEVANCE

MMPs and TIMPs play an essential role in the degradation of the extracellular matrix. The imbalance MMPs and TIMPs can cause periapical tissue destruction. Therefore, the reestablishment of the balance between activated MMPs and TIMPs with root canal therapy is essential to restore tissue homeostasis.

MMP9 protects against LPS-induced inflammation in osteoblasts

The matrix metalloproteinase (MMP) family is widely involved in the destruction of the pulp and apical tissues in the inflammatory process. MMP9 is closely related to oral inflammation. Nevertheless, the specific function of MMP9 during oral inflammation, as well as its mechanism, is not well understood. Our previous studies found that in experimentally induced apical periodontitis, more severe inflammation occurred in MMP9 knockout mice compared with the wild type mice. Moreover, the pathology phenomenon of alveolar bone destruction was even more evident in MMP9 knockout mice compared with the wild type mice. We proposed that MMP9 has “anti-inflammatory” properties. We aimed to study the effects of MMP9 on inflammatory response as well as on bone formation and bone destruction. We found a specific relationship between MMP9 and inflammation. qRT-PCR and Western blot revealed that the production of IL-1β, TNF-α, RANK, RANKL, TLR2, and TLR4 was reduced by MMP9 in LPS-stimulated MC3T3-E1 cells. Meanwhile, the expressions of OPG and OCN were increased by MMP9 in LPS-stimulated cells. MMP9 plays a protective role in LPS-induced inflammation, thereby providing new clues to the prevention and treatment of apical periodontitis.

Periapical bone response to bacterial lipopolysaccharide is shifted upon cyclooxygenase blockage

OBJECTIVES

Infection, inflammation and bone resorption are closely related events in apical periodontitis development. Therefore, we sought to investigate the role of cyclooxygenase (COX) in osteoclastogenesis and bone metabolism signaling in periapical bone tissue after bacterial lipopolysaccharide (LPS) inoculation into root canals.

METHODOLOGY

Seventy two C57BL/6 mice had the root canals of the first molars inoculated with a solution containing LPS from E. coli (1.0 mg/mL) and received selective (celecoxib) or non-selective (indomethacin) COX-2 inhibitor. After 7, 14, 21 and 28 days the animals were euthanized and the tissues removed for total RNA extraction. Evaluation of gene expression was performed by qRT-PCR. Statistical analysis was performed using analysis of variance (ANOVA) followed by post-tests (α=0.05).

RESULTS

LPS induced expression of mRNA for COX-2 (Ptgs2) and PGE2 receptors (Ptger1, Ptger3 and Ptger4), indicating that cyclooxygenase is involved in periapical response to LPS. A signaling that favours bone resorption was observed because Tnfsf11 (RANKL), Vegfa, Ctsk, Mmp9, Cd36, Icam, Vcam1, Nfkb1 and Sox9 were upregulated in response to LPS. Indomethacin and celecoxib differentially modulated expression of osteoclastogenic and other bone metabolism genes: celecoxib downregulated Igf1r, Ctsk, Mmp9, Cd36, Icam1, Nfkb1, Smad3, Sox9, Csf3, Vcam1 and Itga3 whereas indomethacin inhibited Tgfbr1, Igf1r, Ctsk, Mmp9, Sox9, Cd36 and Icam1.

CONCLUSIONS

We demonstrated that gene expression for COX-2 and PGE2 receptors was upregulated after LPS inoculation into the root canals. Additionally, early administration of indomethacin and celecoxib (NSAIDs) inhibited osteoclastogenic signaling. The relevance of the cyclooxygenase pathway in apical periodontitis was shown by a wide modulation in the expression of genes involved in both bone catabolism and anabolism.

Etiologic role of root canal infection in apical periodontitis and its relationship with clinical symptomatology

Evidence shows the polymicrobial etiology of endodontic infections, in which bacteria and their products are the main agents for the development, progression, and dissemination of apical periodontitis. Microbial factors in necrotic root canals (e.g., endotoxin) may spread into apical tissue, evoking and supporting a chronic inflammatory load. Thus, apical periodontitis is the result of the complex interplay between microbial factors and host defense against invasion of periradicular tissues. This review of the literature aims to discuss the complex network between endodontic infectious content and host immune response in apical periodontitis. A better understanding of the relationship of microbial factors with clinical symptomatology is important to establish appropriate therapeutic procedures for a more predictable outcome of endodontic treatment.

Modified Polymeric Nanoparticles Exert In Vitro Antimicrobial Activity Against Oral Bacteria

Polymeric nanoparticles were modified to exert antimicrobial activity against oral bacteria. Nanoparticles were loaded with calcium, zinc and doxycycline. Ions and doxycycline release were measured by inductively coupled plasma optical emission spectrometer and high performance liquid chromatography. Porphyromonas gingivalis, Lactobacillus lactis, Streptoccocus mutans, gordonii and sobrinus were grown and the number of bacteria was determined by optical density. Nanoparticles were suspended in phosphate-buffered saline (PBS) at 10, 1 and 0.1 mg/mL and incubated with 1.0 mL of each bacterial suspension for 3, 12, and 24 h. The bacterial viability was assessed by determining their ability to cleave the tetrazolium salt to a formazan dye. Data were analyzed by ANOVA and Scheffe’s F (p < 0.05). Doxycycline doping efficacy was 70%. A burst liberation effect was produced during the first 7 days. After 21 days, a sustained release above 6 µg/mL, was observed. Calcium and zinc liberation were about 1 and 0.02 µg/mL respectively. The most effective antibacterial material was found to be the Dox-Nanoparticles (60% to 99% reduction) followed by Ca-Nanoparticles or Zn-Nanoparticles (30% to 70% reduction) and finally the non-doped nanoparticles (7% to 35% reduction). P. gingivalis, S. mutans and L. lactis were the most susceptible bacteria, being S. gordonii and S. sobrinus the most resistant to the tested nanoparticles.

Immunohistochemical expression of TGF-β1 and MMP-9 in periapical lesions

The objective of this study was to evaluate the expression of matrix metalloproteinase 9 (MMP-9) and transforming growth factor beta (TGF-β1) in periapical lesion samples correlated with the intensity of the inflammatory infiltrate and thickness of the epithelial lining. Forty-five cases of periapical lesions (23 periapical granulomas and 22 radicular cysts) were subjected to morphological and immunohistochemical analyses using anti-MMP-9 and anti-TGF-β1 antibodies. The data were analyzed using the following tests: non-parametric Mann-Whitney, chi-square, Fisher's exact test and Spearman's correlation test (P<0.05). Analysis of inflammatory infiltrate revealed that 78% of periapical granulomas presented infiltrate grade III, in contrast with 32% of radicular cysts (P<0.001). Morphological evaluation of the epithelial thickness in radicular cysts revealed the presence of atrophic epithelium in 86% of the cysts. The immunostaining of MMP-9 was score 2 in 67% of the granulomas and 77% of the cysts. Both lesions were predominantly score 1 for TGF-β1. Significant differences were confirmed between the expression scores of TGF-β1 and MMP-9 in periapical granulomas (p = 0.004) and in radicular cysts (p < 0.001). Expression of TGF-β1 was different for periapical granulomas and radicular cysts. This immunoregulatory cytokine seems more representative in asymptomatic lesions. The extracellular matrix remodeling process dependent on MMP-9 seems to be similar for both periapical granulomas and radicular cysts. TGF-β1 and MMP-9 may play an important role in the maintenance of periapical lesions.

Bone resorptive activity in symptomatic and asymptomatic apical lesions of endodontic origin

OBJECTIVES

The aim of this study is to assess the levels and diagnostic accuracy of a set of bone resorption biomarkers, including TRAP-5, RANKL, and OPG in symptomatic and asymptomatic apical lesions and controls.

MATERIALS AND METHODS

Apical tissues from symptomatic and asymptomatic apical periodontitis patients and periodontal ligaments from healthy teeth extracted for orthodontic reasons were processed for tissue homogenization and the levels of TRAP-5, RANKL, and OPG were determined by multiplex assay. Marker levels were analyzed by Kruskal Wallis test, and diagnostic accuracy was analyzed with ROC curves.

RESULTS

Higher levels of RANKL, OPG, and RANKL/OPG ratio were determined in both types of apical lesions compared to healthy periodontal ligament, whereas higher TRAP-5 levels were found only in symptomatic apical lesions (p < 0.05). OPG, RANKL, and RANKL/OPG ratio showed diagnostic potential to identify apical lesions versus healthy controls (AUC = 0.69, p < 0.05); while TRAP-5 showed a potential to discriminate symptomatic versus asymptomatic apical periodontitis (AUC = 0.71, p < 0.05) and healthy controls (AUC = 0.83, p < 0.05).

CONCLUSIONS

Apical lesions showed higher RANKL and OPG levels than healthy tissues. TRAP-5 levels were the highest in symptomatic apical lesions, suggesting that these represent a progressive state, and showed diagnostic potential.

CLINICAL RELEVANCE

Clinically symptomatic apical periodontitis might represent biologically progressive apical lesions based on TRAP5 levels. TRAP5 has diagnostic potential to identify these lesions, representing a candidate prognostic biomarker.

Role of Thr399Ile and Asp299Gly polymorphisms of toll-like receptor-4 gene in acute dental abscess

BACKGROUND

Apical Periodontitis (AP) is an inflammatory disease that affects the tissues surrounding the root end of a tooth. The disease which is caused by endodontic infections presents in different clinical ways including development of an acute abscess. Recent studies have provided information suggesting role of a multitude of factors in pathogenesis of acute apical abscess (AAA). In this case-control study, our goal was to evaluate the frequency and potential role of two common polymorphisms of toll like receptor-4 (TLR-4) gene; Thr399Ile (1196 C>T) and Asp299Gly (+896 A>G), in 50 patients with AAA as cases and 50 patients with asymptomatic apical periodontitis (AAP) as controls.

MATERIAL AND METHODS

Saliva sample containing mucosal epithelial cells was used for DNA extraction. Polymorphisms were detected by Tetra-ARMS (Amplification Refractory Mutation System) PCR method. Statistical analyses were carried out in SPSS 21 software.

RESULTS

Homozygous wild type (CC) and heterozygous (CT) genotypes of Thr399Ile polymorphism were detected in 84% and 16% of AAA patients respectively. In controls, respective ratios were 94% (CC) and 6% (CT). Observed difference was not statistically significant (P>0.05) for distribution of these genotypes. The mutant homozygous (TT) genotype of this polymorphism was identified in neither of the participants. Overall, T allele frequency was obtained 8% in AAA and 3% in AAP (OR=2.6, 95% CI; 0. 6-10.6, p>0.05). For Asp299Gly polymorphism, no individual was detected with the mutant allele in case or control groups.

CONCLUSIONS

Our results indicated a possible role for Thr399Ile polymorphism in acute presentations of abscess in AAA. However, the impact of this polymorphism needs to be more assessed in future studies. Key words:Genetic polymorphism, periapical abscess, periapical periodontitis, toll-like receptor 4.

Metalloproteinases 2 and 9 Immunoexpression in Periapical Lesions from Primary Endodontic Infection: Possible Relationship with the Histopathological Diagnosis and the Presence of Pain

INTRODUCTION

The aim of this study was to evaluate the possible associations among the histopathological diagnosis, the inflammatory infiltrate profile, the presence of pain, and the immunoexpression of matrix metalloproteinases MMP-2 and MMP-9 in periapical lesions from primary endodontic infection.

METHODS

Fifty-one primary periapical lesions obtained from extracted teeth were selected for this study. Patients were previously evaluated for the presence of pain and sinus tract related to the tooth to be extracted. Tissues were processed for microscopic examination and MMP-2 and MMP-9 immunoexpression. Microscopically, samples were classified as periapical granulomas or periapical cysts and the inflammatory infiltrate as chronic or mixed. The percentage of immunopositive cells for MMP-2 and MMP-9 of each case was performed based on 10 consecutive microscopic fields. The Student t or chi-square tests were used in the statistical analysis.

RESULTS

Of the total, 28 cases were classified as periapical granulomas (54.90%) and 23 cases as periapical cysts (45.10%). Seventeen patients (33.33%) reported pain associated with the extracted tooth, with 12 cases of periapical granulomas (70.58%) and 5 cases of periapical cysts (29.42%). All cases showed immunopositivity for MMP-2 and MMP-9 in a high percentage of cells, mainly in the cytoplasm of the leukocytes. MMP-2 was expressed more in periapical granulomas than periapical cysts (P < .05) and in symptomatic cases (P < .05).

CONCLUSIONS

According to the results, we may conclude that MMP-2 and MMP-9 are highly expressed in periapical lesions from a primary endodontic infection. Moreover, we may suggest MMP-2 is expressed more in periapical granuloma and in cases associated with pain.

DNA Methylation of MMP9 Is Associated with High Levels of MMP-9 Messenger RNA in Periapical Inflammatory Lesions

INTRODUCTION

Matrix metalloproteinases (MMPs) are the major class of enzymes responsible for degradation of extracellular matrix components and participate in the pathogenesis of periapical inflammatory lesions. MMP expression may be regulated by DNA methylation. The purpose of the present investigation was to analyze the expression of MMP2 and MMP9 in periapical granulomas and radicular cysts and to test the hypothesis that, in these lesions, their transcription may be modulated by DNA methylation.

METHODS

Methylation-specific polymerase chain reaction was used to evaluate the DNA methylation pattern of the MMP2 gene in 13 fresh periapical granuloma samples and 10 fresh radicular cyst samples. Restriction enzyme digestion was used to assess methylation of the MMP9 gene in 12 fresh periapical granuloma samples and 10 fresh radicular cyst samples. MMP2 and MMP9 messenger RNA transcript levels were measured by quantitative real-time polymerase chain reaction.

RESULTS

All periapical lesions and healthy mucosa samples showed partial methylation of the MMP2 gene; however, periapical granulomas showed higher MMP2 mRNA expression levels than healthy mucosa (P = .014). A higher unmethylated profile of the MMP9 gene was found in periapical granulomas and radicular cysts compared with healthy mucosa. In addition, higher MMP9 mRNA expression was observed in the periapical lesions compared with healthy tissues.

CONCLUSIONS

The present study suggests that the unmethylated status of the MMP9 gene in periapical lesions may explain the observed up-regulation of messenger RNA transcription in these lesions.

MMP-7 and TIMP-1, new targets in predicting poor wound healing in apical periodontitis

INTRODUCTION

Matrix metalloproteinases (MMPs) and the tissue inhibitors of metalloproteinases (TIMPs) are strongly associated with tissue destruction because of inflammation. In this study, we investigated the expression of MMPs and TIMPs messenger RNA and protein levels in apical periodontitis lesions.

METHODS

Tissue samples from patients presenting clinical signs of chronic apical abscess (CAA) or asymptomatic apical periodontitis (AAP) were collected postoperatively and used for gene expression analysis of MMP-2, -3, -7, -9, -14, -16, and -25; TIMP-1; and TIMP-2 in real-time polymerase chain reaction. Immunohistochemistry was also performed to detect the expression of MMP-7 and TIMP-1 proteins. Lastly, U-937 cells were induced to terminal differentiation into macrophages, infected with purified Escherichia coli lipopolysaccharide, and assessed for the expression of MMP-7 and TIMP-1 using immunocytochemistry and confocal microscopy.

RESULTS

Significantly higher messenger RNA levels were found for all genes in AAP and CAA samples when compared with healthy control samples (P < .001). AAP cases exhibited significantly higher TIMP-1 when compared with CAA cases, whereas CAA cases showed higher MMP-2, MMP-7, and MMP-9 messenger RNA levels (P < .05). We also detected positive the expression of MMP-7 and TIMP-1 proteins in the tissue samples. The expression of both MMP-7 and TIMP-1 were increased in lipopolysaccharide-stimulated cells compared with nonstimulated cells and appear to colocalize in the Golgi apparatus.

CONCLUSIONS

MMPs appear to have an influential role in CAA cases in which ongoing tissue destruction is observed. TIMPs are preferentially associated with AAP, perhaps as a subsequent defense mechanism against excessive destruction. Taken together, our findings implicate MMP and TIMP molecules in the dynamics of inflammatory periapical lesion development.