Increased human defensine levels hint at an inflammatory etiology of bisphosphonate-associated osteonecrosis of the jaw: an immunohistological study

Human β-defensins and their synthetic analogs: Natural defenders and prospective new drugs of oral health

As a family of cationic host defense peptides, human β-defensins (HBDs) are ubiquitous in the oral cavity and are mainly synthesized primarily by epithelial cells, serving as the primary barrier and aiming to prevent microbial invasion, inflammation, and disease while maintaining physiological homeostasis. In recent decades, there has been great interest in their biological functions, structure-activity relationships, mechanisms of action, and therapeutic potential in oral diseases. Meanwhile, researchers are dedicated to improving the properties of HBDs for clinical application. In this review, we first describe the classification, structural characteristics, functions, and mechanisms of HBDs. Next, we cover the role of HBDs and their synthetic analogs in oral diseases, including dental caries and pulp infections, periodontitis, peri-implantitis, fungal/viral infections and oral mucosal diseases, and oral squamous cell carcinoma. Finally, we discuss the limitations and challenges of clinical translation of HBDs and their synthetic analogs, including, but not limited to, stability, bioavailability, antimicrobial activity, resistance, and toxicity. Above all, this review summarizes the biological functions, mechanisms of action, and therapeutic potential of both natural HBDs and their synthetic analogs in oral diseases, as well as the challenges associated with clinical translation, thus providing substantial insights into the laboratory development and clinical application of HBDs in oral diseases.

Immune Dysfunction in Medication-Related Osteonecrosis of the Jaw

The pathogenesis of medication-related osteonecrosis of the jaw (MRONJ) is multifactorial and there is a substantial consensus on the role of antiresorptive drugs (ARDs), including bisphosphonates (BPs) and denosumab (Dmab), as one of the main determinants. The time exposure, cumulative dose and administration intensity of these drugs are critical parameters to be considered in the treatment of patients, as cancer patients show the highest incidence of MRONJ. BPs and Dmab have distinct mechanisms of action on bone, but they also exert different effects on immune subsets which interact with bone cells, thus contributing to the onset of MRONJ. Here, we summarized the main effects of ARDs on the different immune cell subsets, which consequently affect bone cells, particularly osteoclasts and osteoblasts. Data from animal models and MRONJ patients showed a deep interference of ARDs in modulating immune cells, even though a large part of the literature concerns the effects of BPs and there is a lack of data on Dmab, demonstrating the need to further studies.

Do various imaging modalities provide potential early detection and diagnosis of medication-related osteonecrosis of the jaw? A review

OBJECTIVE

Patients with medication-related osteonecrosis of the jaw (MRONJ) often visit their dentists at advanced stages and subsequently require treatments that greatly affect quality of life. Currently, no clear diagnostic criteria exist to assess MRONJ, and the definitive diagnosis solely relies on clinical bone exposure. This ambiguity leads to a diagnostic delay, complications, and unnecessary burden. This article aims to identify imaging modalities' usage and findings of MRONJ to provide possible approaches for early detection.

METHODS

Literature searches were conducted using PubMed, Web of Science, Scopus, and Cochrane Library to review all diagnostic imaging modalities for MRONJ.

RESULTS

Panoramic radiography offers a fundamental understanding of the lesions. Imaging findings were comparable between non-exposed and exposed MRONJ, showing osteolysis, osteosclerosis, and thickened lamina dura. Mandibular cortex index Class II could be a potential early MRONJ indicator. While three-dimensional modalities, CT and CBCT, were able to show more features unique to MRONJ such as a solid type periosteal reaction, buccal predominance of cortical perforation, and bone-within-bone appearance. MRI signal intensities of vital bones are hypointense on T₁WI and hyperintense on T₂WI and STIR when necrotic bone shows hypointensity on all T₁WI, T₂WI, and STIR. Functional imaging is the most sensitive method but is usually performed in metastasis detection rather than being a diagnostic tool for early MRONJ.

CONCLUSION

Currently, MRONJ-specific imaging features cannot be firmly established. However, the current data are valuable as it may lead to a more efficient diagnostic procedure along with a more suitable selection of imaging modalities.

Antimicrobial peptide gene expression in medication-related osteonecrosis of the jaw

Bisphosphonates and denosumab are commonly used antiresorptive therapies in patients with bone metastasis and osteoporosis. Medication-related osteonecrosis of the jaw (MRONJ) is a serious side effect of these drugs, and infection has been recognized as a contributing factor. Current therapeutic options for MRONJ show limited effectiveness, therefore necessitating novel treatment strategies. Bisphosphonates have recently been reported to induce the expression of antimicrobial peptides (AMPs), an inherent component of the immune system. Therefore, the aim of the present study was to investigate and compare the influence of the anti-RANKL antibody denosumab and bisphosphonates on the gene expression of selected AMPs: human α-defensin-1, human α-defensin-3, human β-defensin-1, and human β-defensin-3. Bone specimens were collected from patients with MRONJ who had been treated with bisphosphonates (n = 6) or denosumab (n = 6), and from healthy subjects (n = 6) with no history of treatment with bone metabolism-influencing drugs. Reverse transcription-quantitative polymerase chain reaction was used to quantify the expression levels of selected AMPs. Samples from patients treated with denosumab showed significantly higher mRNA expression of human α-defensin-3 and human β-defensin-3 than those from healthy subjects. This finding is similar to previously described upregulated expression of human defensins in patients with MRONJ after bisphosphonates treatment. This suggests that the elevated expression of defensins may be at least a part of the mechanism underlying the pathogenesis of osteonecrosis induced by antiresorptive therapies, which can serve as a new target for potential treatment of MRONJ.

Saliva diagnostics in patients suffering from bisphosphonate-associated osteonecrosis of the jaw: Results of an observational study

OBJECTIVE

One of the severe side effects of bisphosphonate (BP) therapy is bisphosphonate-associated osteonecrosis of the jaw (BONJ). However, there is no information available about its pathogenesis. Hence, the aim of this observational study was to contribute to discerning this pathogenesis by comparing salivary quantity and quality in patients with BONJ and undergoing BP treatment.

MATERIALS AND METHODS

This study included 60 patients divided into three groups. The first group consisted of 20 patients with established BONJ, the second group had 20 patients undergoing BP treatment, and the third group comprised 20 healthy individuals. These groups were analysed for the flow rate of stimulated saliva, buffer capacity, and salivary pH level.

RESULTS

Reduced salivation was observed in a significantly high number of patients with established BONJ (n = 8) and those undergoing BP treatment (n = 9) in comparison with the healthy control group (n = 4; p = 0.039). Though the distribution of the mean value of stimulated saliva flow rates in patients undergoing BP treatment was lower than in the control group, the difference was not significant. Moreover, there were no significant differences in the salivary pH level and buffer capacity in patients undergoing BP treatment as compared with the healthy control group.

CONCLUSIONS

It is possible that the quantity of human saliva is affected by BP treatment. This reduction in saliva production could have a negative effect on mucosal health and is perhaps a cofactor in the pathogenesis of BONJ.

Pharmacogenetics of medication-related osteonecrosis of the jaw: a systematic review and meta-analysis

Medication-related osteonecrosis of the jaw (MRONJ) is a severe complication that can develop in patients treated with anti-resorptive drugs. Although the pathogenesis of MRONJ is still unclear, genetic factors have a demonstrated important role. Thus, the aim of this study was to perform a systematic review on the pharmacogenetics of MRONJ. Studies published until March 2019 were retrieved from eight databases and were selected by two independent reviewers. Evidence on several genetic polymorphisms was summarized and a meta-analysis was conducted when possible. Fourteen studies involving 1515 participants were eligible for systematic review. For CYP2C8 rs1934951, no significant difference was observed between the MRONJ and non-MRONJ groups (odds ratio (OR) 2.04, 95% confidence interval (CI) 0.88-4.73, P=0.09). However, a subgroup analysis based on only multiple myeloma status showed a positive association (OR 3.64, 95% CI 1.29-10.30, P=0.01). PPARG rs1152003 was not differently distributed between groups (OR 0.25, 95% CI 0.01-9.92, P=0.46). Also, VEGF rs3025039 was found to be correlated with the occurrence of MRONJ (OR 0.35, 95% CI 0.15-0.82, P=0.02). CYP2C8 rs1934951 (in multiple myeloma patients) and VEGF rs3025039 are associated with the development of MRONJ in patients treated with bisphosphonates. The results are promising and call for new trials with a larger sample to further explore this growing field.

Radiographic bone loss and the risk of medication-related osteonecrosis of the jaw (MRONJ) in multiple myeloma patients-A retrospective case control study

Risk factors for medication-related osteonecrosis of the jaws (MRONJ) include type and duration of antiresorptive drugs, dental trauma, local anatomy, systemic underlying conditions and therapy, smoking, and the presence of periodontal disease. However, there is a lack of studies elucidating the role of periodontal disease as risk predictor. In the present study, the dental charts of 100 multiple myeloma (MM) patients and 16 MM patients who developed MRONJ were studied. Information about age, gender, smoking history, diabetes, steroid drug intake, type and duration of bisphosphonate (BP) treatments, MRONJ status, missing teeth, periapical lesions, widening of the periodontal ligament, and periodontal status was collected. The periodontal status was determined as a percentage of missing bone at the mesial and distal surfaces of each tooth. Multivariable logistic regression was performed to identify risk factors associated with MRONJ. In the selected model, using the COX analysis, categorical bone loss percentage is significantly associated with MRONJ (P = 0.009), with hazard ratio 0.042 (high vs low) and 95% CI 0.004 to 0.453. Gender, steroid, Aredia BP type, and periapical are also significant in selected model. In conclusion, advanced alveolar bone loss and missing teeth were strongly related to the occurrence of MRONJ in MM patients.

Immunoprecipitation high performance liquid chromatographic analysis of healing process in chronic suppurative osteomyelitis of the jaw

PURPOSE

Chronic suppurative osteomyelitis (CSO) of the jaw is one of the most difficult infectious diseases to manage, because it causes progressive bony destruction and is associated with bacterial inhabitation of the sequestra. A combination of antibiotic therapy and surgical debridement is often used to treat CSO. Nevertheless, various systemic conditions can lead to life-threatening complications.

METHODS

The present study aimed to explore the wound healing progress in 16 cases of CSO through protein expression analysis of postoperative exudates (POE) that were collected 6 h, 1 day, and 2 days after saucerization and/or decortication. A bony lesion was removed during surgery and then examined pathologically, and the CSO POE was examined by immunoprecipitation thus high performance chromatography (IP-HPLC). The POE at 6 h was used as a comparative control.

RESULTS

Histologically the CSO lesion showed a necrotic granulomatous lesion heavily infiltrated with polymorphonuclear leukocytes, macrophages, and plasma cells, admixed with multiple sequestra inhabited by bacterial colonies. The IP-HPLC analysis displayed a slight increase in innate immunity-related proteins, i.e., NFkB, TNFα, IL-1, IL-6, IL-28, and LL-37, but a gradual decrease of bacteria-related inflammatory proteins, i.e., IL-8, IL-12, CD31, CD68, and lysozyme. The angiogenesis-related proteins, i.e., VEGF-A and VEGF-C, were slightly decreased but TGF-β1 and bFGF were markedly increased on day 2. The osteogenesis-related proteins, i.e., OPG and ALP, were slightly increased, while the osteoclastogenesis-related protein, RANKL was slightly decreased compared to the control.

CONCLUSION

These findings indicate that the infected CSO undergoes a rapid wound healing process with active osteogenesis and a gradual decrease in bacteria-related inflammation, predicting a favorable prognosis after surgery. Moreover, IP-HPLC can be useful in monitoring the POE and wound healing processes during the postoperative period.

Bacterial diversity in medication-related osteonecrosis of the jaw

OBJECTIVE

The aim was to study the association between microflora and medication-related osteonecrosis of the jaw (MRONJ) by using culture-independent molecular techniques to detect bacteria in necrotic bone lesions.

STUDY DESIGN

Included were 18 consecutive patients with MRONJ, 10 with osteoporosis and 8 cancer patients. Bone biopsies were retrieved from the center of the necrotic bone and from visually healthy bone, and 16 S rRNA gene fragments from bacterial DNA were amplified with polymerase chain reaction.

RESULTS

The study revealed a diversity of bacteria represented by 16 S rRNA sequences in all the necrotic bone samples and in 60% of the visually healthy bone. Eight dominating taxa groups were identified at the genus level: Porphyromonas, Lactobacillus, Tannerella, Prevotella, Actinomyces, Treponema, Streptococcus, and Fusobacterium.

CONCLUSIONS

The necrotic bone lesions contained mainly anaerobic bacteria, representative of periodontal microflora, suggesting that a periodontal infection in combination with antiresorptive treatment could initiate osteonecrosis.

Radiotherapy for oral cancer decreases the cutaneous expression of host defence peptides

INTRODUCTION

Bacterial resistance against antibiotics has become an increasing challenge in the treatment of cutaneous infections. Consequences can be severe, especially in infected wounds following previous local radiotherapy. Certain endogenous peptide antibiotics, the host defence peptides (HDPs), exhibit broad-spectrum antimicrobial activity and promote wound healing. Their use as supplements to conventional antibiotics is a current topic of discussion; however, knowledge of their quantities in healthy and compromised tissue is a prerequisite for such discussion. To date, no data concerning HDP quantities in irradiated skin are available.

METHODS

Expression profiles of the genes encoding HDPs, namely human beta-defensin-1 (DEFB1, hBD-1), beta-defensin-2 (DEFB4A, hBD-2), beta-defensin-3 (DEFB103, hBD-3) and S100A7, were assessed in samples of non-irradiated and irradiated neck.

RESULTS

A reduction in the expression of all of the examined genes was observed in irradiated skin when compared with non-irradiated skin (statistically significant in the case of S100A7, P = 0.013). Immunohistochemistry revealed differences in HDP distribution with respect to the epithelial layers.

CONCLUSION

The study demonstrates a significant reduction in HDP gene expression in neck skin as a result of radiotherapy. These findings might represent a starting point for novel treatments of cutaneous infections in irradiated patients, such as topical supplementation of synthetic HDP.

Current concepts in pathogenesis of acute and chronic osteomyelitis

PURPOSE OF REVIEW

The term osteomyelitis covers a wide range of inflammatory bone disorders caused by microbial invasion or due to autoinflammatory processes, but furthermore osteomyelitis also occurs at different ages and at preferred localizations in the human skeleton. This article aims to give an overview of the current literature focussing on pathognomonic aspects of osteomyelitis because of microbial invasion.

RECENT FINDINGS

Outlining the chronological sequence of osteomyelitis originating from the invasion of microbes finally leading to destruction of bone tissue, the formation and proliferation of biofilm structures play a key role in the development of inflammatory bone disorders. The components of the biofilm on the one hand mediate an immune response leading to an increase of local cytokines and induction of osteoclastogenesis but on the other hand also directly interact with the osteoblasts. As a result, the bone-remodelling process is immensely diminished by induction of proapoptotic pathways, decreased proliferation and differentiation of osteoblasts and an additional promotion of osteoclastogenesis.

SUMMARY

Although microbial invasion is responsible to be the cause for inflammatory bone disorders, except for an autoinflammatory origin, the underlying and detailed mechanisms in the pathogenesis of osteomyelitis are not yet fully understood, but represent an absolute precondition for the development of effective causal treatment strategies in the future.

Osteonecrosis of the jaw in a Crohn's disease patient following a course of Bisphosphonate and Adalimumab therapy: a case report

Background

Bisphosphonates have a widespread indication for osteoporosis and are also applied in cancer patients with skeletal-related conditions. Bisphosphonate-associated osteonecrosis of the jaw (BRONJ) is a feared side effect which is hard to treat and often affects patient´s quality of life in an extensive manner. Adalimumab (Humira®), a fully human recombinant antibody specific for tumor necrosis factor- α, is approved for treatment in patients with Inflammatory Bowel Disease like ulcerative colitis or Crohn’s disease.

Case presentation

In March 2013, a 36-year-old female presented with right-sided perimandibular swelling, recurrent facial pain and exposed necrotic bone after previous extraction of tooth 47. She had the medical history of Crohn’s disease for more than one decade with chronic active enterocolitis, fistula disease as well as previous oral manifestation and was currently treated with Adalimumab since September 2008. Due to steroid-induced osteoporosis, diagnosed in 2004, she received oral Bisphosphonates (Risedronate) from 2004 until 2007 followed by two infusions of Zoledronic acid in 2008 and 2009.

Conclusion

This patient with a medical history of Crohn’s disease and gastrointestinal remission under Adalimumab therapy presented with osteonecrosis of the jaw after suspended oral and intravenous Bisphosphonate therapy implicating that the biologic therapy with an anti-TNF-α antibody might promote the manifestation of osteonecrosis and compromise oral healing capacity.

Nitrogen containing bisphosphonates associated osteonecrosis of the jaws: A review for past 10 year literature

Nitrogen containing bisphosphonate (N-BP) therapy is used extensively to treat osteoporosis and osteolytic bone lesions. Recently, a special form of osteonecrosis limited to the maxillofacial skeleton has been discovered especially within those patients who are receiving either long-term N-BP therapy alone and/or associated with invasive dental procedure. Bisphosphonates accumulate almost exclusively in maxillofacial skeleton owing to high bone turn over remodeling to maintain the mechanical competence. The pathogenesis and why it commonly appears in maxillofacial skeleton and the fixed treatment strategies remains unknown. The aim of this study was to improve the clinician understanding of N-BPs associated osteonecrosis of maxillofacial skeleton by reviewing the past 10 year literature.

Bisphosphonate Related Osteonecrosis of the Jaw: An Update

OBJECTIVES

The aim of this paper is to summarize different diagnostic criteria as well as probable aetiopathogenesis of bisphosphonates related osteonecrosis of the jaw.

MATERIALS AND METHODS

The electronic search of peer-reviewed journals were performed in MEDLINE (PubMed) database in order to find the relevant articles on bisphosphonates related osteonecrosis of the jaw (BP-related ONJ). The search was restricted to English language articles, published from January 2002 to May 2013. On the basis of these articles, probable aetiopathogenesis and different diagnostic criteria of BP-related ONJ were summarized.

RESULTS

BP-related ONJ is related to the development of avascular necrosis or dead jaw bones. In recent literature many given hypotheses show the aetiopathogenesis and diagnosis of BP-related ONJ which are interlinked and have multifactorial nature. Their diagnosis revolves around four main diagnostic criteria that differentiate it from other conditions which can delay bone healing.

CONCLUSIONS

Factors like potency of bisphosphonates, biology of jaw bone, antiangiogenic property of bisphosphonates and soft tissue toxicity in combination with present infection, other drugs, pre-existing pathologies, compromised immune response and dentoalveolar trauma may lead to development of BP-related ONJ.