Oxidative stress in bisphosphonate-related osteonecrosis of the jaws

S-Allylmercapto-N-Acetylcysteine (ASSNAC) Attenuates Osteoporosis in Ovariectomized (OVX) Mice

Osteoporosis is a bone-debilitating disease, demonstrating a higher prevalence in post-menopausal women due to estrogen deprivation. One of the main mechanisms underlying menopause-related bone loss is oxidative stress. S-allylmercapto-N-acetylcysteine (ASSNAC) is a nuclear factor erythroid 2-related factor 2 (Nrf2) activator and cysteine supplier, previously shown to have anti-oxidation protective effects in cultured cells and animal models. Here, we studied the therapeutic potential of ASSNAC with and without Alendronate in ovariectomized (OVX) female mice. The experimental outcome included (i) femur and L3 lumbar vertebra morphometry via Micro-Computed Tomography (μCT); (ii) bone remodeling (formation vs. resorption); and (iii) oxidative stress markers in bone marrow (BM) cells. Four weeks after OVX, there was a significant bone loss that remained evident after 8 weeks, as demonstrated via µCT in the femur (cortical and trabecular bone compartments) and vertebra (trabecular bone). ASSNAC at a dose of 50 mg/Kg/day prevented bone loss after the four-week treatment but had no significant effect after 8 weeks, while ASSNAC at a dose of 20 mg/Kg/day significantly protected against bone loss after 8 weeks of treatment. Alendronate prevented ovariectomy-induced bone loss, and combining it with ASSNAC further augmented this effect. OVX mice demonstrated high serum levels of both C-terminal cross-linked telopeptides of type I collagen (CTX) (bone resorption) and procollagen I N-terminal propeptide (P1NP) (bone formation) after 2 weeks, and these returned to control levels after 8 weeks. Alendronate, ASSNAC and their combination decreased CTX and increased P1NP. Alendronate induced oxidative stress as reflected by decreased glutathione and increased malondialdehyde (MDA) levels, and combining it with ASSNAC partially attenuated these changes. These results portray the therapeutic potential of ASSNAC for the management of post-menopausal osteoporosis. Furthermore, ASSNAC ameliorates the Alendronate-associated oxidative stress, suggesting its potential to prevent Alendronate side effects as well as improve its bone-protective effect.

Resveratrol for preventing medication-related osteonecrosis of the jaws in rats

This study evaluated the effect of resveratrol (RES) on the prevention of medication-related osteonecrosis of the jaws (MRONJ) in ovariectomized (OVX) rats treated with zoledronate (ZOL). Fifty rats were distributed in five groups: SHAM (n = 10): non-ovariectomy + placebo; OVX (n = 10):ovariectomy + placebo; OVX + RES (n = 10):ovariectomy + resveratrol; OVX + ZOL (n = 10):ovariectomy + placebo + zoledronate; and OVX + RES + ZOL (n = 10):ovariectomy + resveratrol + zoledronate. The mandibles left sides were analyzed with micro-CT, histomorphometry, and immunohistochemistry. On the right side, bone markers gene expression was analyzed by qPCR. ZOL increased the percentage of necrotic bone and reduced the neo-formed bone compared to groups not receiving ZOL (p < 0.05). RES impacted the tissue healing pattern in OVX + ZOL + RES, reduced inflammatory cell infiltrate, and improved bone formation in the extraction site. Osteoblasts, alkaline phosphatase (ALP)-, and osteocalcin (OCN)-immunoreactive cells were lower in OVX-ZOL than in SHAM, OVX, and OVX-RES. The OXV-ZOL-RES had fewer osteoblasts and ALP- and OCN-cells than the SHAM and OVX-RES. The tartrate-resistant acid phosphatase (TRAP)-positive cells were reduced in the presence of ZOL (p < 0.05), while the TRAP mRNA levels increased with ZOL treatment, with or without resveratrol, compared with the other groups (p < 0.05). RES alone increased superoxide dismutase levels compared to OVX + ZOL and OVX + ZOL + RES (p < 0.05). In conclusion, resveratrol reduced the tissue impairment severity induced by ZOL; however, it could not prevent the occurrence of MRONJ.

Ozone therapy effect in medication-related osteonecrosis of the jaw as prevention or treatment: microtomographic, confocal laser microscopy and histomorphometric analysis

OBJECTIVE

This study aimed to evaluate the efficacy of ozone therapy in the preoperative (prevention) and/or postoperative (treatment) of MRONJ.

MATERIAL AND METHODS

Forty male Wistar rats were caudally treated with zoledronic acid (ZOL) and to ozone therapy before extraction (prevention, POG), after extraction (treatment, TOG), or both (prevention and treatment, TPOG), and treated with saline (SAL). The animals received intramuscular fluorochrome (calcein and alizarin), and 28 days postoperatively, they were euthanized, and the tissues were subjected to microtomographic computed tomography (microCT), LASER confocal, and histomorphometric analyses.

RESULTS

Micro-CT showed a higher bone volume fraction average in all groups than that in the ZOL group (P < 0.001), the ZOL group showed high porosity (P = 0.03), and trabecular separation was greater in the TOG group than in the POG group (P < 0.05). The mineral apposition rate of the POG group was high (20.46 ± 6.31) (P < 0.001), followed by the TOG group (20.32 ± 7.4). The TOG group presented the highest mean newly formed bone area (68.322 ± 25.296) compared with the ZOL group (P < 0.05), followed by the SAL group (66.039 ± 28.379) and ZOL groups (60.856 ± 28.425).

CONCLUSIONS

Ozone therapy modulated alveolar bone repair in animals treated with ZOL, mainly after surgery trauma, leading to bone formation as healing tissue.

CLINICAL RELEVANCE

Osteonecrosis has been a challenge in dentistry, and owing to the lack of a consensus regarding therapy, studies presenting new therapies are important, and ozone has been one of the therapies explored empirically.

ANOM Approach for Statistical Evaluation of Some Antioxidant Enzyme Activities

Free radicals are chemical molecules that are more reactive and have an unpaired electron. Free radicals formed inside the cell oxidize biomolecules, leading to cell death and tissue damage. Antioxidants are molecules that can stabilize or inactivate free radicals before they damage the cell. In this study; the availability of Malondialdehyde, Superoxide dismutase, Catalase and Reduced glutathione levels as markers for related diseases was evaluated by examining whether and in what range they may vary in some diseases. In study, nine groups consist of prostate cancer, cirrhosis, liver transplantation, chronic kidney damage, acute kidney injury, X-ray exposure, CT exposure, MR exposure and Osteonecrosis. Analysis of means is a method developed to compare group means with the overall mean and presents the results graphically in an easy-to-understand manner without the required for any post hoc test. In addition, related characteristics were categorized as “low and high” and Nonlinear Principal Component Analysis was conducted to visually present their relationship with related disease types in two-dimensional space. The upper and lower decision lines were found 3.123 and 2.794 μmol/L, respectively for Malondialdehyde. Those with cirrhosis, chronic kidney disease, acute kidney disease and tomography exposure were included in the upper and lower decision lines. Those with prostate cancer, osteonecrosis, and X-ray exposure were above the upper decision line and are found higher than the overall mean. Those with lung transplantation and MR exposure appear to be below the lower decision line and lower than the overall mean. The present study provides the first comprehensive assessment of the availability of Malondialdehyde, Superoxide dismutase, Catalase and Reduced glutathione levels as markers for some related diseases. This study has shown that Analysis of means can be used as an alternative graphical procedure for multiple group comparisons with an overall mean in the studies regarding as biochemical characteristics and relating diseases. In addition, Nonlinear Principal Component Analysis can be useful aid for decision marker in some biochemical characteristics and related diseases.

Quantitative proteomics in medication-related osteonecrosis of the jaw: a proof-of-concept study

OBJECTIVE

Medication-related osteonecrosis of the jaw (MRONJ) is a paradoxical effect associated with bone modifying agents (BMAs) and other drugs. Currently no valuable diagnostic or prognosis biomarkers exist. This goal of this research was to study MRONJ related salivary proteome.

MATERIALS AND METHODS

This case-control aimed to study salivary proteome in MRONJ versus control groups i) formed from BMAs consumers and ii) healthy individuals to unravel biomarkers. 38 samples of unstimulated whole saliva (18 MRONJ patients, 10 BMA consumers, and 10 healthy controls) were collected. Proteomic analysis by SWATH-MS coupled to bioinformatics analysis was executed.

RESULTS

586 proteins were identified, 175 proteins showed significant differences among MRONJ versus controls. SWATH-MS revealed differentially expressed proteins among three groups, which have never isolated. These proteins had distinct roles including cell envelope organization, positive regulation of vesicle fusion, positive regulation of receptor binding, or regulation of low-density lipoprotein particle clearance. Integrative analysis prioritised 3 proteins (MMP9, AACT and HBD). Under receiver operating characteristic analysis, this panel discriminated MRONJ with a sensitivity of 90% and a specificity of 78.9%.

CONCLUSION

These findings may inform of a novel biomarker panel for MRONJ prediction or diagnosis. Nonetheless, further research is needed to validate this panel.

Modulation of Cellular Redox Parameters for Improving Therapeutic Responses in Multiple Myeloma

Raised oxidative stress and abnormal redox status are typical features of multiple myeloma cells, and the identification of the intimate mechanisms that regulate the relationships between neoplastic cells and redox homeostasis may reveal possible new anti-myeloma therapeutic targets to increase the effectiveness of anti-myeloma drugs synergistically or to eradicate drug-resistant clones while reducing toxicity toward normal cells. An alteration of the oxidative state is not only responsible for the onset of multiple myeloma and its progression, but it also appears essential for the therapeutic response and for developing any chemoresistance. Our review aimed to evaluate the literature’s current data on the effects of oxidative stress on the response to drugs generally employed in the therapy of multiple myeloma, such as proteasome inhibitors, immunomodulators, and autologous transplantation. In the second part of the review, we analyzed the possibility of using other substances, often of natural origin, to modulate the oxidative stress to interfere with the progression of myelomatous disease.

Zoledronic acid promotes osteoclasts ferroptosis by inhibiting FBXO9-mediated p53 ubiquitination and degradation

Bisphosphonates (BPs)-related osteonecrosis of jaw (BRONJ) is a severe complication of the long-term administration of BPs. The development of BRONJ is associated with the cell death of osteoclasts, but the underlying mechanism remains unclear. In the current study, the role of Zoledronic acid (ZA), a kind of bisphosphonates, in suppressing the growth of osteoclasts was investigated and its underlying mechanism was explored. The role of ZA in regulating osteoclasts function was evaluated in the RANKL-induced cell model. Cell viability was assessed by cell counting kit-8 (CCK-8) assay and fluorescein diacetate (FDA)-staining. We confirmed that ZA treatment suppressed cell viability of osteoclasts. Furthermore, ZA treatment led to osteoclasts death by facilitating osteoclasts ferroptosis, as evidenced by increased Fe²⁺, ROS, and malonyldialdehyde (MDA) level, and decreased glutathione peroxidase 4 (GPX4) and glutathione (GSH) level. Next, the gene expression profiles of alendronate- and risedronate-treated osteoclasts were obtained from Gene Expression Omnibus (GEO) dataset, and 18 differentially expressed genes were identified using venn diagram analysis. Among these 18 genes, the expression of F-box protein 9 (FBXO9) was inhibited by ZA treatment. Knockdown of FBXO9 resulted in osteoclasts ferroptosis. More important, FBXO9 overexpression repressed the effect of ZA on regulating osteoclasts ferroptosis. Mechanistically, FBXO9 interacted with p53 and decreased the protein stability of p53. Collectively, our study showed that ZA induced osteoclast cells ferroptosis by triggering FBXO9-mediated p53 ubiquitination and degradation.

Various Therapeutic Methods for the Treatment of Medication-Related Osteonecrosis of the Jaw (MRONJ) and Their Limitations: A Narrative Review on New Molecular and Cellular Therapeutic Approaches

Medication-related osteonecrosis of the jaw (MRONJ) is one of the most interesting diseases in the field of maxillofacial surgery. In addition to bisphosphonates, the use of antiresorptive and antiangiogenic agents is known to be the leading cause. However, the exact pathogenesis of MRONJ has not been established, and various hypotheses have been proposed, such as oxidative stress-related theory. As a result, a definitive treatment protocol for MRONJ has not been identified, while various therapeutic approaches are applied to manage patients with MRONJ. Although the surgical approach to treat osteomyelitis of the jaw has been proven to be most effective, there are limitations, such as recurrence and delayed healing. Many studies and clinical trials are being conducted to develop another effective therapeutic modality. The use of some materials, including platelet concentrates and bone morphogenetic proteins, showed a positive effect on MRONJ. Among them, teriparatide is currently the most promising material, and it has shown encouraging results when applied to patients with MRONJ. Furthermore, cell therapy using mesenchymal stem cells showed promising results, and it can be the new therapeutic approach for the treatment of MRONJ. This review presents various treatment methods for MRONJ and their limitations while investigating newly developed and researched molecular and cellular therapeutic approaches along with a literature review.

Common and Novel Markers for Measuring Inflammation and Oxidative Stress Ex Vivo in Research and Clinical Practice-Which to Use Regarding Disease Outcomes?

Many chronic conditions such as cancer, chronic obstructive pulmonary disease, type-2 diabetes, obesity, peripheral/coronary artery disease and auto-immune diseases are associated with low-grade inflammation. Closely related to inflammation is oxidative stress (OS), which can be either causal or secondary to inflammation. While a low level of OS is physiological, chronically increased OS is deleterious. Therefore, valid biomarkers of these signalling pathways may enable detection and following progression of OS/inflammation as well as to evaluate treatment efficacy. Such biomarkers should be stable and obtainable through non-invasive methods and their determination should be affordable and easy. The most frequently used inflammatory markers include acute-phase proteins, essentially CRP, serum amyloid A, fibrinogen and procalcitonin, and cytokines, predominantly TNFα, interleukins 1β, 6, 8, 10 and 12 and their receptors and IFNγ. Some cytokines appear to be disease-specific. Conversely, OS-being ubiquitous-and its biomarkers appear less disease or tissue-specific. These include lipid peroxidation products, e.g., F2-isoprostanes and malondialdehyde, DNA breakdown products (e.g., 8-OH-dG), protein adducts (e.g., carbonylated proteins), or antioxidant status. More novel markers include also -omics related ones, as well as non-invasive, questionnaire-based measures, such as the dietary inflammatory-index (DII), but their link to biological responses may be variable. Nevertheless, many of these markers have been clearly related to a number of diseases. However, their use in clinical practice is often limited, due to lacking analytical or clinical validation, or technical challenges. In this review, we strive to highlight frequently employed and useful markers of inflammation-related OS, including novel promising markers.

The Effect of Photobiomodulation on Nitrite and Inflammatory Activity in Radiotherapy-Induced Oral Mucositis: A Randomized Clinical Trial

BACKGROUND AND OBJECTIVES

To investigate pro- and anti-inflammatory cytokines and nitrite salivary levels in patients with head and neck cancer receiving photobiomodulation therapy (PBMT) associated with a Preventive Oral Care Program (POCP), for prevention and control of oral mucositis (OM) during radiotherapy (RT) associated or not with chemotherapy protocol.

STUDY DESIGN/MATERIALS AND METHODS

In this randomized double-blinded clinical trial, 48 patients were randomly assigned to two groups: PBMT (n = 25) and Control (n = 23). In the PBMT group, patients were submitted to PBMT associated with the POCP. In the Control group, patients were submitted only to the POCP. Saliva samples were collected in the 1st (baseline), 7th, 14th, 21st, and 30th sessions of RT, and the levels of interleukin-6 (IL-6), IL-8, IL-10, IL-12p70, IL-1β, and tumoral necrosis factor-α (TNF-α) were measured using the cytometric bead array. Nitrite levels were measured by colorimetric method. OM was assessed using the World Health Organization and the National Cancer Institute scales.

RESULTS

Patients in the PBMT group presented less severe OM. PBMT tended to stabilize nitrite concentration levels during the RT regimen. The IL-1β concentration was associated with higher OM scores. PBMT promoted an increase in IL-12p70, TNF-α, and IL-10 concentration.

CONCLUSION

PBMT was effective in the prevention and control of severe OM, and its mechanism of action may be related to a better balance of inflammatory response that may favor injury control. Lasers Surg. Med. © 2020 Wiley Periodicals LLC.

Reactive oxygen/nitrogen species (ROS/RNS) and oxidative stress in arthroplasty

The interplay between implant design, biomaterial characteristics, and the local microenvironment adjacent to the implant is of utmost importance for implant performance and success of the joint replacement surgery. Reactive oxygen and nitrogen species (ROS/RNS) are among the various factors affecting the host as well as the implant components. Excessive formation of ROS and RNS can lead to oxidative stress, a condition that is known to damage cells and tissues and also to affect signaling pathways. It may further compromise implant longevity by accelerating implant degradation, primarily through activation of inflammatory cells. In addition, wear products of metallic, ceramic, polyethylene, or bone cement origin may also generate oxidative stress themselves. This review outlines the generation of free radicals and oxidative stress in arthroplasty and provides a conceptual framework on its implications for soft tissue remodeling and bone resorption (osteolysis) as well as implant longevity. Key findings derived from cell culture studies, animal models, and patients' samples are presented. Strategies to control oxidative stress by implant design and antioxidants are explored and areas of controversy and challenges are highlighted. Finally, directions for future research are identified. A better understanding of the host-implant interplay and the role of free radicals and oxidative stress will help to evaluate therapeutic approaches and will ultimately improve implant performance in arthroplasty.

Oxidative Stress Indexes for Diagnosis of Health or Disease in Humans

Oxidative stress (OS) is the imbalance between oxidant and antioxidant molecules, in favor of oxidants, that causes aging and disease. Many studies have been published that demonstrate the relationship between OS and human health and disease; however, the following questions arise: (i) how are we sure that the OS is present in a biological process? (ii) Is the OS reported in the different investigations equivalent? (iii) What are the best oxidant and antioxidant markers for OS diagnosis? (iv) Can we establish the types and the intensity of the OS? (v) Does OS index could be useful for research and/or application in clinical medicine? In this regard, several indexes have been proposed to measure OS in humans relative to the state of health and disease, among which the following can be highlighted: Oxidative Stress Index (OSI), Tiol Ratios (-SH/TT, -SS/-SH, and-SS/TT), Glutathione Ratio (GSSG/GSH), Oxidative Stress Score (OSS), and OXY-index. Therefore, the aim of this review is to present the state of the art of knowledge about OS indexes for diagnosis of health or disease in humans. We searched for articles in English or Spanish in the PubMed/MEDLINE and Scopus electronic databases published up until May 2019. The keywords used were “oxidative stress,” “index,” and “oxidative stress index.” It was identified 11479 records in both databases, and 490 articles were analyzed. Our review suggests that all indexes analyzed allow diagnose and differentiate the OS related to human health and disease. Also, the studies on OSI, Oxy-score, and OSS indexes have proven to be reliable, practical, and with clinical utility. However, it is necessary to continue with longitudinal studies, especially assess the usefulness of the indexes in the clinical prognosis, and make comparative studies between the different indexes.

Vasculature submucosal changes at early stages of osteonecrosis of the jaw (ONJ)

Osteonecrosis of the jaw (ONJ), a rare, but potentially severe side effect of anti-resorptive medications, presents as exposed bone in the maxillofacial region lasting for at least 8 weeks. While clinical experience and animal models concur in finding that systemic antiresorptive treatment in conjunction with local risk factors, such as tooth extraction or dental disease may lead to ONJ development, the subclinical molecular changes that precede bone exposure remain poorly understood. The identification of these changes is not only important in understanding disease pathophysiology, but could provide potential for treatment development. Here, we evaluated the early stages of ONJ utilizing a model of experimental periodontitis (EP) in mice treated with two different types of antiresorptives, targeting potential changes in vasculature, hypoxia, oxidative stress, and apoptosis. Antiresorptive treatment in animals with EP increased levels of empty osteocytic lacunae and increased ONJ prevalence compared to Veh animals. The arteriole and venule network seen around EP areas was diminished in animals treated with antiresorptives. Higher levels of vascular endothelial growth factor A (VEGF-A) and vascular cell adhesion protein-1 (VCAM-1) were observed 1-week following EP in treated animals. Finally, levels of hypoxia, oxidative stress, and apoptosis remained high in antiresorptive treated animals with EP through the duration of the experiment. Together, our data point to subclinical vasculature organizational disturbances that subsequently affect levels of hypoxia, oxidative stress, and apoptosis in the area of developing ONJ.

Association between biomarkers and medication-related osteonecrosis of the jaws: a systematic review

OBJECTIVES

Our aim was to conduct a systematic review (SR) of the literature assessing the role of human biomarkers in the diagnosis or prognostication of medication-related osteonecrosis of the jaws (MRONJ).

STUDY DESIGN

An electronic search without date or language restriction was carried out in PubMed/MEDLINE, the Cochrane Central Register of Controlled Trials, Web of Science, and LILACS for publications until March 2018. In addition, a manual search in the gray literature was conducted. The search process was performed by 2 independent reviewing authors. Eligibility criteria included randomized and nonrandomized clinical trials, prospective or retrospective cohorts, case controls, and case series evaluating the association between biomarkers and MRONJ. The protocol of this SR was registered in PROSPERO under number CRD42018095886.

RESULTS

The search and selection process yielded 19 studies (2 case series, 6 case-control studies, 9 prospective cohort studies, and 2 retrospective studies) published between 2008 and 2018. Twenty-four biomarkers collected from serum, saliva, and urine were investigated by these studies. Eleven biomarkers were possibly related to MRONJ; however, no consensus is observed in the literature with regard to the sensitivity and clinical effectiveness of these biomarkers.

CONCLUSIONS

Although many biomarkers have been associated with MRONJ, the present SR found scarce clinical evidence supporting the use of these biomarkers for the diagnosis and prognosis of MRONJ.

Enhanced In Situ Availability of Aphanizomenon Flos-Aquae Constituents Entrapped in Buccal Films for the Treatment of Oxidative Stress-Related Oral Diseases: Biomechanical Characterization and In Vitro/Ex Vivo Evaluation

In recent years, the key role of oxidative stress in pathogenesis of oral diseases has been emphasized and the use of antioxidant agents has been encouraged. Aphanizomenon flos-aquae (AFA) is a unicellular blue-green alga with antioxidant and anti-inflammatory properties. The aim of this study was the formulation and characterization of mucoadhesive thin layer films loaded with AFA, finalized to the treatment of oxidative stress (OS)-related oral diseases. First, to enhance the bioavailability of AFA constituents, the raw food grade material was appropriately treated by a high frequency homogenization able to disrupt cell walls. Thus, Eudragit^® E100-based buccal films were produced by the solvent casting method, containing 7% and 18% of AFA. The films, characterized by uniformity in thickness, weight, and drug content, showed low swelling degree, good muco-adhesiveness and controlled drug release. The mechanical tests showed elastic moduli of films of almost 5 MPa that is well-suitable for human buccal applications without discomfort, besides biaxial tests highlighted a marked material isotropy. Permeation studies through porcine mucosae demonstrated the ability of films to promote AFA penetration in the tissues, and when sublingually administered, they produced a drug flux up to six-fold higher than an AFA solution. The new formulations represent an interesting alternative for the development of cosmetics and nutraceuticals with a functional appeal containing plant extracts.

Biomarkers to predict the onset of biphosphonate-related osteonecrosis of the jaw: A systematic review

Background

The goal of this paper was to identify available biomarkers to predict the onset of biphosphonate-related osteonecrosis of the jaw (BRONJ).

Material and Methods

Case-control studies comparing the different concentrations of a series of molecules detected in serum and urine as matrices of BRONJ affected patients vs. non-affected were included. PRISMA guidelines for systematic reviews were used for the present paper. Two reviewers independently screened electronic databases (Medline, Web of science, and The Cochrane Library) and performed hand searches. Risk of bias assessment of selected studies was performed by the Newcastle-Ottawa Scale. This study is registered as PROSPERO CRD42017078149.

Results

From a total of 601 identified studies, 7 (4 articles with high methodological quality and 3 with medium) articles were included. They investigate 2623 patients, of whom 91 (3.47%) developed BRONJ. A total of 7 biomarkers were identified and classified into 3 groups: bone turnover, angiogenesis and endocrine markers. Conflicting results were found in relation to most biomarkers.

Conclusions

The present review suggests that no useful markers are currently available to evaluate BRONJ risk. Nevertheless, the present paper indicates that a paradigm shift from bone turnover biomarkers to angiogenesis and endocrine markers could shed light on this search.

Key words:Biphosphonate, jaw, osteonecrosis, osteoporosis.

Zoledronic Acid, Bevacizumab and Dexamethasone-Induced Apoptosis, Mitochondrial Oxidative Stress, and Calcium Signaling Are Decreased in Human Osteoblast-Like Cell Line by Selenium Treatment

Increased intracellular free calcium ion (Ca²⁺) concentration induces excessive oxidative stress and apoptosis. Medical procedures such as zoledronic acid (Zol), bevacizumab (Bev), and dexamethasone (Dex) are usually used in the treatment of bone diseases (osteoporosis, Paget's disease, etc.) and to prevent metastasis in the bone although the procedures induce osteonecrosis of the jaw through excessive production of reactive oxygen species (ROS). Recently, we observed regulator roles of selenium (Se) on apoptosis and Ca²⁺ entry through transient receptor potential vanilloid 1 (TRPV1) channels in the cancer cell lines. Therefore, Se may modulate Zol, Bev, and Dex-induced oxidative stress and apoptosis through regulation of TRPV1 channel. In the current study, we investigated the protective effects of Se on apoptosis and oxidative stress through TRPV1 in Zol, Bev, and Dex-induced osteoblast-like cell line. We used human osteoblast-like cell line (Saos-2), and the cells were divided into 12 groups as control, Zol, Bev, Dex, Se, Zol+Se, Bev+Se, Dex+Se, Zol+Dex, Zol+Dex+Se, Zol+Bev, and Zol+Bev+Se which were incubated with drugs (Zol, Bev, Dex, and Se) for 24 h. The cytosolic free Ca²⁺ concentration was increased by Zol, Bev, Dex, Zol+Bev, and Zol+Dex, although it was reduced by Se treatment. However, Zol, Bev, and Dex-induced increase in apoptosis, caspase 3, caspase 9, poly (ADP-ribose) polymerase 1 expression levels, and intracellular ROS production values in the cells were decreased by Se treatments. In conclusion, we observed that Zol, Bev, and Dex-induced apoptosis, mitochondrial oxidative stress, and calcium signaling are decreased in human osteoblast-like cell line by the Se treatment. Our findings may be relevant to the etiology and treatment of Zol, Bev, and Dex-induced osteonecrosis by Se.

Vitamin D supplementation: Hypothetical effect on medication-related osteonecrosis of the jaw

Vitamin D is an important nutrient for bone health and skeleton growth. Few foods are natural sources of this secosteroid; this is the reason why the consumption of vitamin D as a dietary supplement is becoming common in developed countries. For many years vitamin D has been considered crucial in the treatment and prevention of the Global Burden of Disease and in a reduction in mortality among elder people. Many health care providers prescribe these supplements in the management of osteoporosis and metabolic bone diseases; specifically in the primary prevention of fractures. Recently medication-related osteonecrosis of the jaw (MRONJ) has been reported as severe late sequelae of antiresorptive therapies (i.e., bisphosphonates and some monoclonal antibodies). Although MRONJ-related pathophysiology is not fully understood, there are three fundamental theories to explain it: (1) the inhibition of osteoclasts, (2) the inhibition of angiogenesis and (3) the processes of inflammation-infection. Recent advances in Vitamin D research have shown that this secosteroid can play a potential pivotal role in many of the different etiological pathways of MRONJ. Furthermore, there are a large number of co-morbidities between the deficit of this vitamin and other MRONJ concomitant outcomes. Our hypothesis argues that the low-risk and low-cost vitamin D dietary supplementation may prove to be suitable for use as a practical MRONJ prevention strategy. The described framework gives more insight into the study of disease mechanisms, search of potential biomarkers, and therapeutic targets in MRONJ.

Chronic treatment with zoledronic acid increases inflammatory markers in periodontium of rats

BACKGROUND

Bisphosphonates (BF) rise proinflammatory markers and irreversibly bind to bone. Chronically, BF can lead to an inflammatory status and can increase the local oxidative stress in periodontium. Therefore, the objective of this study was to evaluate whether the chronic infusion of Zoledronic Acid (ZA) increases inflammatory markers in periodontium of rats.

METHODS AND RESULTS

Chronically, infusion therapy was performed with ZA (0.04, 0.2 or 1 mg/kg or saline) by four doses in over a 70-day period to analyze periodontium of the first right inferior molar using histologic, histochemical (toluidine blue), and immunohistochemical (CD68, tumor necrosis factor-α (TNF-α), interleukin-1beta (IL-1β), inducible nitric oxide synthase (iNOS) and nuclear factor kappa B (NF-kB)) tests. The experiment was replicated (ZA 0.2 mg/kg versus saline) for myeloperoxidase (MPO) assay and dose TNF-α, IL-1β, malondialdehyde (MDA) and glutathione (GSH) in gingiva of the same tooth. Despite there is no alteration in mast cells (P = .608) and CD68 mononuclear-positive cells (P = .351), in the periodontium of the ZA-treated group, was observed an increase in the presence of inflammatory cells (P = .001) and cytoplasmic immunostaining for TNF-α (P = .003), IL-1b (P = .004), iNOS (P = .008), and NF-kB (P =  .025). Levels of MPO (P < .001), TNF-α (P = .002), IL-1β (P < .001), and GSH (P = .005) were augmented in gingiva of ZA-treated group but MDA (P = .993) levels and NF-kB nuclear staining (P = .923) were not altered.

CONCLUSIONS

Chronic treatment with ZA increase proinflammatory cytokines and the number of inflammatory cells in periodontium of rats and GSH are expressed probably in a compensatory manner.

Serum levels of RANKL and OPG, and the RANKL/OPG ratio in bisphosphonate-related osteonecrosis of the jaw: Are they useful biomarkers for the advanced stages of osteonecrosis?

Background

We determined whether serum levels of Receptor Activator for Nuclear Factor κ B Ligand (RANKL), Osteoprotegerin (OPG), and the RANKL/OPG ratio could be useful biomarkers for the severity of oral lesions in bisphosphonate-related osteonecrosis of the jaw (BRONJ).

Material and Methods

A case-control study in which Group 1 consisted of 41 patients with BRONJ due to intravenous bisphosphonates, and Group 2 consisted of 44 healthy control cases. The plasma levels of RANKL and OPG were analyzed by an ELISA assay. The OPG/RANKL ratio was also calculated. We determined if the mean serum values differed among the different stages of BRONJ.

Results

Serum levels of RANKL were lower in Group 1 than in Group 2 (p =0.01), and serum levels of OPG were higher in patients with BRONJ than in the controls (p =0.006). The ratio of RANKL/OPG was greater in the controls than in Group 1 (P >0.01). There were no significant differences in the serum levels of RANKL and OPG among the different stages of osteonecrosis (P > 0.05).

Conclusions

Serum levels of RANKL and OPG, and the RANKL/OPG ratio were not valuable biomarkers for determining the severity of oral lesions in patients with BRONJ.

Key words:Bisphosphonates, RANKL, OPG, Osteonecrosis.

Interrelationship of clinical, radiographic and haematological features in patients under bisphosphonate therapy

OBJECTIVES

To analyze the clinical, radiographic and haematological aspects of patients under bisphosphonate therapy.

METHODS

A retrospective study was conducted where the records of patients taking bisphosphonates were analyzed considering the occurrence of bisphosphonate-related osteonecrosis of the jaw (BRONJ). Evaluation included panoramic and periapical radiographies, haematological examinations and clinical features. Radiographies were analyzed determining the presence or absence of bone sclerosis, osteolysis, persisting alveolar socket, narrowing of the mandibular canal, widening of the periodontal ligament space, periradicular radiolucency, sequestrum and thickening of the lamina dura. Laboratory tests consisted of complete blood count, fasting serum glucose, erythrocyte sedimentation rate (ESR) and serum levels of calcium, phosphorus, alkaline phosphatase, parathormone (PTH) and C-terminal telopeptide of collagen I (CTX).

RESULTS

Alkaline phosphatase and ESR were significantly higher in the BRONJ group, whereas fasting serum glucose, CTX, PTH, calcium and phosphorus did not significantly differ. BRONJ showed association with smoking, tooth extraction, anaemia and leukocytosis. On radiographic analysis, persisting alveolar socket, osteolysis, bone sclerosis and narrowing of the mandibular canal were significantly more prevalent in the BRONJ group. Thickening of the lamina dura, periapical radiolucencies, widening of the periodontal ligament space and sequestrum did not significantly differ between the groups.

CONCLUSIONS

BRONJ is a multifactorial disease with high morbidity, which requires experimental studies to clarify the role of the reported risk factors and clinical radiographic signs to improve its diagnosis.

Immune cellular profile of bisphosphonate-related osteonecrosis of the jaw

OBJECTIVES

Characterize the cell profile and immunostaining of proinflammatory markers in an experimental model of bisphosphonate-related osteonecrosis of the jaw (BRONJ).

MATERIALS AND METHODS

Male Wistar rats (n = 6-7) were treated chronically with saline solution or zoledronic acid (ZA) at 0.04, 0.20, and 1.00 mg kg(-1) (1.4 × 10(-7) , 6.9 × 10(-6) , and 3.4 × 10(-5)  mol kg(-1) ), and subsequently, the first left inferior molar was extracted. Were performed counting of viable and empty osteocyte lacunae, viable and apoptotic osteoclasts, polymorphonuclear neutrophil, mast cells (toluidine blue), and the positive presence cells for CD68, tumor necrosis factor-alpha (TNF-α), IL (interleukin)-1β, inducible nitric oxide synthase (iNOS), nuclear factor-kappa B (NF-kB) and IL-18 binding protein (IL-18 bp).

RESULTS

BRONJ was showed in ZA treated with 0.20 and 1.00 mg kg(-1) . There is a dose dependent increase in percentage of empty osteocyte lacunae (P < 0.001) and apoptotic osteoclasts (P < 0.001), counting of total osteoclasts (P = 0.003), polymorphonuclear neutrophil cells (P = 0.009), cytoplasmic-positive cells of CD68 (P < 0.001), TNF-α (P = 0.001), IL-1β (P = 0.001), iNOS (P < 0.001), NF-kB (P = 0.006), and nuclear-positive cells of NF-kB (P = 0.011). Consequently, there is no difference in mast cells (P = 0.957), and IL-18 bp immunostaining decreases dose dependently (P = 0.005).

CONCLUSIONS

BRONJ is characterized by increases in immunostaining for proinflammatory markers and NF-kB and inversely associated with cells exhibiting IL-18 bp.

Can saliva testing replace blood measurements for health monitoring? Insights from a correlation study of salivary and whole blood glutathione in humans

The feasibility of using saliva samples as diagnostic for health status is assessed.

Oxidative stress plays an important role in zoledronic acid-induced autophagy

Several pre-clinical and clinical studies have demonstrated zoledronic acid (Zol), which regulates the mevalonate pathway, has efficient anti-cancer effects. Zol can also induce autophagy. The aim of this study is to add new understanding to the mechanism of autophagy induction by Zol. LC3B-II, the marker for autophagy was increased by Zol treatment in breast cancer cells. Autophagosomes induced by Zol were visualized and quantified in both transient (pDendra2-hLC3) and stable MCF-7-GFP-LC3 cell lines. Acidic vesicular organelles were quantified using acridine orange. Zol induced a dose and time dependent autophagy. Treatment of Zol increased oxidative stress in MCF-7 cells, which was reversed by GGOH or anti-oxidants. On the other hand, treatment with GGOH or anti-oxidants resulted in decreased levels of LC3B-II. Further, the induced autophagy was irreversible, as the washout of Zol after 2 h or 24 h resulted in similar levels of autophagy, as induced by continuous treatment after 72 h. Thus, it can be summarized that Zol can induce a dose dependent but irreversible autophagy, by its effect on the mevalonate pathway and oxidative stress. This study adds to the understanding of the mechanism of action of Zol, and that it can induce autophagy at clinically relevant shorter exposure times in cancer cells.

Correlation of changes in the mandible and retina/choroid vasculature of a rat model of BRONJ

Bisphosphonate-related osteonecrosis of the jaw (BRONJ) causes bones of the mandible and maxilla to become necrotic and protrude into the oral cavity. Compromised blood supply to bone is also a feature of BRONJ. The design of this study was first to use our established technique of molar extraction and IV bisphosphonate injection to produce features of BRONJ in rats that mimic the human disease; second to confirm vascular changes in the mandible and eye using micro-CT of vascular casts, and image analysis of retina/choroid images; and third to show parallel bisphosphonate-induced changes in the structure and markers of the vasculature of the bone and eye. The results of this study show structural changes in the eye and mandible as well as biochemical changes including the up-regulation of VEGF in response to the bisphosphonate-associated ischemia. These changes are not associated with angiogenesis in either the eye or mandible as determined by reduced vascular complexity. These results suggest that observations of direct changes to the vasculature in the retina/choroid structures of the eye in patients taking bisphosphonates could serve as a window to the progression of debilitating changes occurring as a result of bisphosphonate therapy.

[Current approaches for early detection and treatment of medication-related osteonecrosis of jaw]

Owing to the increased life expectancy, the incidence of rheumatoid disorders and oncologic cases with bone metastasis has dramatically increased. Despite the beneficial effects of the applied antiresorptive and antiangiogenic drugs (e.g. bisphosphonates), serious side effects such as jaw osteonecrosis may also develop. The aim of the authors was to summarize present knowledge about the possibilities of prevention and treatment in medication-related osteonecrosis of the jaw. Based on literature data, currently used detection methods for medication-related osteonecrosis of the jaw (including their advantages and limitations) are summarized. In addition, novel trends of surgical and adjuvant therapeutic approaches are also reviewed. The authors conclude that possibilities of prevention and efficacy of therapeutic interventions in this disorder are still limited possibly due to an incomplete knowledge of the underlying pathomechanism. An interdisciplinary cooperation for prevention and attentive monitoring in order to decrease the incidence of iatrogenic oral and maxillofacial complications seems to be particularly important.

Diabetes as a risk factor for medication-related osteonecrosis of the jaw

Medication-related osteonecrosis of the jaw (MRONJ) is a severe devastating complication for which the exact pathogenesis is not completely understood. Multiple systemic and local factors may contribute to the development of MRONJ. A growing body of evidence supports diabetes mellitus (DM) as an important risk factor for this complication; however, the exact mechanism by which DM may promote MRONJ has yet to be determined. The current review elucidates the role of DM in the pathogenesis of MRONJ and the mechanisms by which DM may increase the risk for MRONJ. Factors related to DM pathogenesis and treatment may contribute to poor bone quality through multiple damaged pathways, including microvascular ischemia, endothelial cell dysfunction, reduced remodeling of bone, and increased apoptosis of osteoblasts and osteocytes. In addition, DM induces changes in immune cell function and promotes inflammation. This increases the risk for chronic infection in the settings of cancer and its treatment, as well as antiresorptive medication exposure, thus raising the risk of developing MRONJ. A genetic predisposition for MRONJ, coupled with CYP 450 gene alterations, has been suggested to affect the degradation of medications for DM such as thiazolidinediones and may further increase the risk for MRONJ.