H2 O2 activates matrix metalloproteinases through the nuclear factor kappa B pathway and Ca(2+) signals in human periodontal fibroblasts

The role of reactive oxygen species in the regulation of the blood-brain barrier

The blood-brain barrier (BBB) regulates the exchange of metabolites and cells between the blood and brain, and maintains central nervous system homeostasis. Various factors affect BBB barrier functions, including reactive oxygen species (ROS). ROS can act as stressors, damaging biological molecules, but they also serve as secondary messengers in intracellular signaling cascades during redox signaling. The impact of ROS on the BBB has been observed in multiple sclerosis, stroke, trauma, and other neurological disorders, making blocking ROS generation a promising therapeutic strategy for BBB dysfunction. However, it is important to consider ROS generation during normal BBB functioning for signaling purposes. This review summarizes data on proteins expressed by BBB cells that can be targets of redox signaling or oxidative stress. It also provides examples of signaling molecules whose impact may cause ROS generation in the BBB, as well as discusses the most common diseases associated with BBB dysfunction and excessive ROS generation, open questions that arise in the study of this problem, and possible ways to overcome them.

Association between ethylene oxide exposure and periodontitis: a cross-sectional study from NHANES 2013-2014

BACKGROUND

Exposure to ethylene oxide (EO) induces inflammation and oxidative stress, which are the main mechanisms of periodontitis. However, the effect of EO on periodontal health is not unclear. In this study, we aimed to explore the relationship between EO exposure and the risk of periodontitis in general US adults.

METHODS

Data used in our study from the National Health and Nutritional Examination Survey (NHANES) 2013-2014. The EO biomarker, hemoglobin adduct of EO (HbEO), was measured in blood samples utilizing high-performance liquid chromatography-tandem mass spectrometry. Periodontitis category was defined by the CDC/AAP according to clinical periodontal parameters. Natural cubic spline, weight multivariable logistic regression analyses and subgroup analysis were used to explore the association between EO exposure and the risk of periodontitis.

RESULTS

A total of 1497 participants over the age of 30 were included in our study. A non-linear positive association with periodontitis was identified for HbEO levels. Participants in the highest tertile of HbEO levels were more likely to have poorer periodontal health compared to the lowest tertile (ORtertile3vs1 = 2.80, 95% CI: 1.85-4.24). Similar results were also found in different subgroups.

CONCLUSIONS

HbEO levels are positively associated with poor periodontal health in US adults. Additional longitudinal studies are necessary to further enhance our comprehension of the impact of exposure to EO on periodontal status.

The Evaluation of Saliva Oxidative and Antioxidative Markers’ Levels in Adolescents with Gingival Inflammation

Periodontal disease is highly prevalent and affects 10%–15% of the world population. Salivary markers of oxidative stress and antioxidant status represent promising tool for research of oral diseases. Given the importance of reactive oxygen species (ROS) in the pathogenesis of periodontal disease, the aim of this study was to determine the association between oxidative stress parameters and periodontal disease gingivitis in adolescents. The study included a consecutive sample of 80 male and female participants referred to the Institute of Dentistry, Kragujevac, Serbia, as a result of periodontal problems or for routine control, aged 18 to 21, with definitive dentition as an inclusion criterion. Patients were divided into three groups depending on their gingival inflammation status. The first group was control group (n=20) with no gingival inflammation, the second group was with mild gingival inflammation (n=19), the third group was with moderate gingival inflammation (n=21) and the fourth group was with severe gingival inflammation (n=20). Oxidative stress parameters were measured in unstimulated whole saliva samples (superoxide anion radical, hydrogen peroxide, nitric oxide, index of lipid peroxidation, reduced gluthatione, catalase and superoxide dismutase). We have found increased levels of hydrogen peroxide and reduced glutathione in the saliva of patients with moderate levels of gingival inflammation, while the other markers were not significantly affected. In conclusion, oxidative stress plays a central role in the pathogenesis and the determination of oxidative and antioxidative levels could be a potent tool in controlling the development of gingivitis.

Treponema denticola-Induced RASA4 Upregulation Mediates Cytoskeletal Dysfunction and MMP-2 Activity in Periodontal Fibroblasts

The periodontal complex consists of the periodontal ligament (PDL), alveolar bone, and cementum, which work together to turn mechanical load into biological responses that are responsible for maintaining a homeostatic environment. However oral microbes, under conditions of dysbiosis, may challenge the actin dynamic properties of the PDL in the context of periodontal disease. To study this process, we examined host-microbial interactions in the context of the periodontium via molecular and functional cell assays and showed that human PDL cell interactions with Treponema denticola induce actin depolymerization through a novel actin reorganization signaling mechanism. This actin reorganization mechanism and loss of cell adhesion is a pathological response characterized by an initial upregulation of RASA4 mRNA expression resulting in an increase in matrix metalloproteinase-2 activity. This mechanism is specific to the T. denticola effector protein, dentilisin, thereby uncovering a novel effect for Treponema denticola-mediated RASA4 transcriptional activation and actin depolymerization in primary human PDL cells.

The Promising Role of Antioxidant Phytochemicals in the Prevention and Treatment of Periodontal Disease via the Inhibition of Oxidative Stress Pathways: Updated Insights

There is growing evidence on the involvement of oxidative stress, which is simply described as the imbalance between oxidants and antioxidants in favor of the former, in the development of periodontal disease that is the most common inflammatory disease in the oral cavity. Thus, the potential of antioxidant phytochemicals as adjunctively preventive and therapeutic agents against the initiation and progression of periodontal disease is a topic of great interest. The current review firstly aims to provide updated insights about the immuno-inflammatory pathway regulated by oxidative stress in periodontal pathology. Then, this work further presents the systemic knowledge of antioxidant phytochemicals, particularly the pharmacological activities, which can be utilized in the prevention and treatment of periodontal disease. Additionally, the challenges and future prospects regarding such a scope are figured out.

Hyperhomocysteinemia: an instigating factor for periodontal disease

Hyperhomocysteinemia (HHcy) affects bone remodeling, since a destructive process in cortical alveolar bone has been linked to it; however, the mechanism remains at large. HHcy increases proinflammatory cytokines viz. TNF-α, IL-1b, IL-6, and IL-8 that leads to a cascade that negatively impacts methionine metabolism and homocysteine cycling. Further, chronic inflammation decreases vitamins B12, B6, and folic acid that are required for methionine homocysteine homeostasis. This study aims to investigate a HHcy mouse model (cystathionine β-synthase deficient, CBS^+/-) for studying the potential pathophysiological changes, if any, in the periodontium (gingiva, periodontal ligament, cement, and alveolar bone). We compared the periodontium side-by-side in the CBS^+/- model with that of the wild-type (C57BL/6J) mice. Histology and histomorphometry of the mandibular bone along with gene expression analyses were carried out. Also, proangiogenic proteins and metalloproteinases were studied. To our knowledge, this research shows, for the first time, a direct connection between periodontal disease during CBS deficiency, thereby suggesting the existence of disease drivers during the hyperhomocysteinemic condition. Our findings offer opportunities to develop diagnostics/therapeutics for people who suffer from chronic metabolic disorders like HHcy.

The Connection of Periodontal Disease and Diabetes Mellitus: The Role of Matrix Metalloproteinases and Oxidative Stress

Diabetes mellitus, a chronic disease considered by the World Health Organization to be an epidemic, is now recognized as one of the factors behind the onset of periodontal disease. The connection between periodontal disease, which is an irreversible inflammatory disease of the supporting tissue of the teeth, and systemic diseases is reflected in the existence of common risk factors, subgingival dental biofilm, as a constant source of proinflamma-tory cytokines synthesized intensely in inflammatory periodontium. Diabetes mellitus leads to increased oxidative stress in periodontal tissues causing worsening of the disease and periodontopathy exacerbates deficiency of pancreatic β-cells. The most important role in primary inflammatory response in the pathogenesis of periodontopathy is played by neutrophils. Neutrophils cause periodontium destruction by the release of enzymes (matrix metalloproteinases), cytotoxic substances (free radicals, reactive oxygen and nitrogen species) and the expression of membrane receptors. Matrix metalloproteinases within the “protease network” are critical to many physiological and pathological processes, including immunity, inflammation, bone resorption and wound healing. Matrix metalloproteinases levels are elevated in patients with metabolic syndrome and diabetes mellitus, which may contribute to more frequent complications. In this paper, the review of available literature data shows the correlation between periodontal disease and diabetes mellitus, as well as the role of matrix metalloproteinases and oxidative stress in these. In this regard, determining the value of matrix metalloproteinases may be helpful in the diagnosis of periodontal disease complicated by diabetes mellitus. Also, the parameters of oxidative stress could help to clarify the mechanisms of pathogenesis and etiology of periodontal disease, or indicate the potential benefit of antioxidant supplementation in these individuals. As the role of matrix metalloproteinases has not been fully clarified in the pathogenesis of periodontopathy, additional studies will be needed to indicate their importance.

Stimulation of cell invasion by the Golgi Ion Channel GAAP/TMBIM4 via an H2O2-Dependent Mechanism

The mechanisms by which the Golgi apparatus (GA) impacts on cell invasion are poorly understood. The human Golgi Anti-Apoptotic Protein (hGAAP, also known as TMBIM4) is a highly conserved Golgi cation channel that modulates intracellular Ca²⁺ fluxes. Human GAAP is expressed in all human tissues, is essential for cell viability and provides resistance against a range of apoptotic stresses. Furthermore, hGAAP enhances adhesion and cell migration by increasing the turnover of focal adhesions due to activation of store-operated Ca²⁺ entry. Here, we describe a GA-derived mechanism that controls cell invasion. The overexpression of hGAAP stimulates 3-dimensional proteolytic cell invasion by a mechanism that is dependent on the accumulation of intracellular hydrogen peroxide_, which might be produced by the hGAAP-dependent stimulation of mitochondrial respiration. These findings provide new insight into the complex mechanisms by which Ca²⁺ and reactive oxygen species signaling contribute to cell invasion and to the role of the GA in these processes.

IL‑18 promotes the secretion of matrix metalloproteinases in human periodontal ligament fibroblasts by activating NF‑κB signaling

Chronic periodontitis is the most common periodontal disease and is characterized by progressive degeneration of periodontal tissue. Periodontal‑specific pathogens can induce the expression of various inflammatory cytokines in periodontal ligament cells and their secretion into peripheral blood. These inflammatory cytokines have an important role in the occurrence and development of chronic periodontitis. ELISA was used to detect the expression of interleukin‑18 (IL‑18) protein in the serum and saliva of 30 healthy volunteers and 30 patients with chronic periodontitis. The clinical parameters that were assessed included plaque index, gingival index, periodontal probing depth and attachment loss. The effect of IL‑18 on the viability of human periodontal ligament fibroblasts (hPDLFs) was examined using a Cell Counting Kit‑8 assay. The effects of IL‑18 on mRNA expression and secretion of matrix metalloproteinase (MMP)1, MMP2, MMP3 and MMP9 in hPDLFs were detected by reverse transcription‑quantitative polymerase chain reaction and ELISA, respectively. The effect of IL‑18 on the phosphorylation of nuclear factor‑κB (NF‑κB) p65 protein and the protein expression of MMP1, MMP2, MMP3 and MMP9 in hPDLF cells was detected by western blotting. The expression level of IL‑18 in the serum of patients with chronic periodontitis was significantly higher than that of healthy volunteers, and the expression level of IL‑18 in saliva was positively correlated with the periodontal destruction. However, IL‑18 did not have a significant effect on the viability ability of hPDLFs. IL‑18 promoted phosphorylation of NF‑κB p65 protein in hPDLF, and increased the mRNA expression and protein secretion of MMP1, MMP2, MMP3 and MMP9. These findings indicate that IL‑18 promotes the secretion of MMP1, MMP2, MMP3, and MMP9 in hPDLFs by activating the NF‑κB signaling pathway, which has a key role in the development of chronic periodontitis. Therefore, targeting IL‑18 may be a new research direction for the treatment of chronic periodontal disease.

Bioactive glass-ceramic bone repair associated or not with autogenous bone: a study of organic bone matrix organization in a rabbit critical-sized calvarial model

OBJECTIVE

The aim of the study was to analyze bone matrix (BMX) organization after bone grafting and repair using a new bioactive glass-ceramic (Biosilicate^®) associated or not with particulate autogenous bone graft.

MATERIAL AND METHODS

Thirty rabbits underwent surgical bilateral parietal defects and divided into groups according to the materials used: (C) control-blood clot, (BG) particulate autogenous bone, (BS) bioactive glass-ceramic, and BG + BS. After 7, 14, and 30 days post-surgery, a fragment of each specimen was fixed in - 80 °C liquid nitrogen for zymographic evaluation, while the remaining was fixed in 10% formalin for histological birefringence analysis.

RESULTS

The results of this study demonstrated that matrix organization in experimental groups was significantly improved compared to C considering collagenous organization. Zymographic analysis revealed pro-MMP-2, pro-MMP-9, and active (a)-MMP-2 in all groups, showing gradual decrease of total gelatinolytic activity during the periods. At day 7, BG presented more prominent gelatinolytic activity for pro-MMP-2 and 9 and a-MMP-2, when compared to the other groups. In addition, at day 7, a 53% activation ratio (active form/[active form + latent form]) was evident in C group, 33% in BS group, and 31% in BG group.

CONCLUSION

In general, BS allowed the production of a BMX similar to BG, with organized collagen deposition and MMP-2 and MMP-9 disponibility, permitting satisfactory bone remodeling at the late period.

CLINICAL RELEVANCE

The evaluation of new bone substitute, with favorable biological properties, opens the possibility for its use as a viable and efficient alternative to autologous bone graft.

Human periodontal ligament fibroblasts synthesize C-reactive protein and Th-related cytokines in response to interleukin (IL)-6 trans-signalling

AIM

To characterize the potential of human periodontal ligament fibroblasts (HPLF) to synthesize CRP and Th-related cytokines in response to IL-6 in periodontal health and apical inflammation.

METHODOLOGY

Primary HPLF stimulated with IL-6, soluble(s) IL-6 receptor (R) and controls were assayed for CRP, Th1, Th2, Th17 and Treg-related cytokines by quantitative real-time PCR and ELISA, respectively. IL-6R mRNA expression and its soluble protein levels were screened in HPLF cultures, and ex vivo samples of healthy periodontal ligaments (n = 5) and apical lesions (n = 13). Data were analysed with ANOVA or unpaired t-test.

RESULTS

0.5 ng mL^-1 IL-6 plus 1 ng mL^-1 of its soluble receptor (sIL-6R) for 24 h was effective in inducing CRP production. IL-6 alone had a mild dose-dependent effect; co-stimulation with sIL-6R significantly enhanced this effect, whereas it was completely abolished by the addition of IL-6R blocking antibody (P < 0.05). Similarly, higher mRNA expression and protein levels of Th1, Th17 and partially Treg-related cytokines were found for IL-6 combined with its soluble receptor versus the nonstimulated group and IL-6R antibody (P < 0.05). IL-6R mRNA expression was slightly induced by IL-6 compared to THP-1 cells, but sILR-6 protein could not be detected in HPLF. High sIL-6R levels were detected in apical lesions and were immunolocalized to mononuclear inflammatory cells and proliferating epithelium.

CONCLUSION

IL-6 trans-signalling induced Th1 and Th17-related cytokines and represents an extra-hepatic mechanism for PCR synthesis in human periodontal ligament fibroblasts, contributing to explain the bone-destructive phenotype of apical lesions and eventually its systemic complications.

Oxidative Stress in the Local and Systemic Events of Apical Periodontitis

Oxidative stress is involved in the pathogenesis of a variety of inflammatory disorders. Apical periodontitis (AP) usually results in the formation of an osteolytic apical lesion (AL) caused by the immune response to endodontic infection. Reactive oxygen species (ROS) produced by phagocytic cells in response to bacterial challenge represent an important host defense mechanism, but disturbed redox balance results in tissue injury. This mini review focuses on the role of oxidative stress in the local and associated systemic events in chronic apical periodontitis. During endodontic infection, ligation of Toll-like receptors (TLRs) on phagocytes' surface triggers activation, phagocytosis, synthesis of ROS, activation of humoral and cellular responses, and production of inflammatory mediators, such as, cytokines and matrix metalloproteinases (MMPs). The increment in ROS perturbs the normal redox balance and shifts cells into a state of oxidative stress. ROS induce molecular damage and disturbed redox signaling, that result in the loss of bone homeostasis, increased pro-inflammatory mediators, and MMP overexpression and activation, leading to apical tissue breakdown. On the other hand, oxidative stress has been strongly involved in the pathogenesis of atherosclerosis, where a chronic inflammatory process develops in the arterial wall. Chronic AP is associated with an increased risk of cardiovascular diseases (CVD) and especially atherogenesis. The potential mechanisms linking these diseases are also discussed.

Matrix Metalloproteinases as Regulators of Periodontal Inflammation

Periodontitis are infectious diseases characterized by immune-mediated destruction of periodontal supporting tissues and tooth loss. Matrix metalloproteinases (MMPs) are key proteases involved in destructive periodontal diseases. The study and interest in MMP has been fuelled by emerging evidence demonstrating the broad spectrum of molecules that can be cleaved by them and the myriad of biological processes that they can potentially regulate. The huge complexity of MMP functions within the 'protease web' is crucial for many physiologic and pathologic processes, including immunity, inflammation, bone resorption, and wound healing. Evidence points out that MMPs assemble in activation cascades and besides their classical extracellular matrix substrates, they cleave several signalling molecules-such as cytokines, chemokines, and growth factors, among others-regulating their biological functions and/or bioavailability during periodontal diseases. In this review, we provide an overview of emerging evidence of MMPs as regulators of periodontal inflammation.

Matrix metalloproteinases regulate extracellular levels of SDF-1/CXCL12, IL-6 and VEGF in hydrogen peroxide-stimulated human periodontal ligament fibroblasts

Periodontitis is a highly prevalent infectious disease characterized by the progressive inflammatory destruction of tooth-supporting structures, leading to tooth loss. The underling molecular mechanisms of the disease are incompletely understood, precluding the development of more efficient screening, diagnostic and therapeutic approaches. We investigated the interrelation of three known effector mechanisms of the cellular response to periodontal infection, namely reactive oxygen species (ROS), matrix metalloproteinases (MMPs) and cytokines in primary cell cultures of human periodontal ligament fibroblast (hPDLF). We demonstrated that ROS increase the activity/levels of gelatinolytic MMPs, and stimulate cytokine secretion in hPDLF. Additionally, we proved that MMPs possesses immune modulatory capacity, regulating the secreted levels of cytokines in ROS-stimulated hPDLF cultures. This evidence provides further insight in the molecular pathogenesis of periodontitis, contributing to the future development of more effective therapies.