Resolvin D1 modulates periodontal ligament fibroblast function

BACKGROUND

The resolution of inflammation is an active process mediated by specialized lipid mediators called lipoxins and resolvins. Periodontal ligament fibroblasts (PDLFs) play a significant role in periodontal regeneration. The purpose of the current study was to determine the impact of resolvin D1 (RvD1) on human PDLF cell wound healing and proliferation, receptor expression (G-protein-coupled receptor 32 [GPR32] and formyl peptide receptor 2 [ALX/FPR2]), and cytokine expression and release.

METHODS

PDLFs were stimulated with interleukin-1β (IL-1β) (500 pg/ml) with and without RvD1 (100 nM). RvD1 receptor expression was determined by quantitative real-time polymerase chain reaction (qPCR), immunofluorescence microscopy, and fluorescence-activated cell sorting. Wound closure was measured by a scratch assay, and proliferation was determined by bromodeoxyuridine incorporation. Interleukin-6 (IL-6), interleukin-8 (IL-8), monocyte chemoattractant protein-1, cyclooxygenase-2, matrix metalloproteinases-1, -2, and -3 (MMP-1, -2, and -3), tissue inhibitors of metalloproteinases-1 and -2 (TIMP-1 and -2), prostaglandin E2, and osteoprotegerin (OPG) gene expression and production were measured using qPCR and Western blotting, multiplex immunoassay, and enzyme-linked immunosorbent assay.

RESULTS

PDLF expressed GPR32 and ALX/FPR2. RvD1 reversed IL-1β-induced inhibition of wound healing and proliferation of PDLF. IL-1β also induced the production of proinflammatory cytokines and MMPs. This effect was reversed by RvD1. RvD1 reversed IL-1β-induced inhibition of TIMP-1, TIMP-2, and OPG.

CONCLUSION

The data suggested that RvD1 has a pro-wound healing, proliferative, and anti-inflammatory impact on the PDLF that favors periodontal regeneration.

The Anti-Inflammatory Effects of Iberin on TNF-α-Stimulated Human Oral Epithelial Cells: In Vitro Research

Iberin is a bioactive chemical found in cruciferous plants that has been demonstrated to have anticancer properties. However, there have been no reports on its effects on periodontal resident cells, and many questions remain unanswered. The aim of this study was to examine whether iberin had anti-inflammatory effects on human oral epithelial cells, including influences on signal transduction pathway activation in TNF-α-στιμυλατεd χελλσ. Iberin inhibited the production of interleukin (IL)-6 and C-X-C motif chemokine ligand 10 (CXCL10), as well as the expression of vascular cell adhesion molecule (VCAM)-1, inducible nitric oxide synthase (iNOS), and cyclooxygenase (COX)-2 in tumor necrosis factor (TNF)-α-stimulated TR146 cells, a human oral epithelial cell line. Moreover, iberin administration increased the expression of antioxidant signaling pathways, such as Heme Oxygenase (HO)-1 and NAD(P)H quinone dehydrogenase 1 (NQO1). Furthermore, we found that iberin could inhibit the activation of the nuclear factor (NF)-κB, signal transducer and activator of transcription (STAT)3, and p70S6 kinase (p70S6K)-S6 ribosomal protein (S6) pathways in TNF-α-stimulated TR146 cells. In conclusion, iberin reduced inflammatory mediator expression in human oral epithelial cells by preventing the activation of particular signal transduction pathways.

Consensus statement for perioperative care in lumbar spinal fusion: Enhanced Recovery After Surgery (ERAS®) Society recommendations

BACKGROUND

Enhanced Recovery After Surgery (ERAS) evidence-based protocols for perioperative care have led to improvements in outcomes in numerous surgical areas, through multimodal optimization of patient pathway, reduction of complications, improved patient experience and reduction in the length of stay. ERAS represent a relatively new paradigm in spine surgery.

PURPOSE

This multidisciplinary consensus review summarizes the literature and proposes recommendations for the perioperative care of patients undergoing lumbar fusion surgery with an ERAS program.

STUDY DESIGN

This is a review article.

METHODS

Under the impetus of the ERAS® society, a multidisciplinary guideline development group was constituted by bringing together international experts involved in the practice of ERAS and spine surgery. This group identified 22 ERAS items for lumbar fusion. A systematic search in the English language was performed in MEDLINE, Embase, and Cochrane Central Register of Controlled Trials. Systematic reviews, randomized controlled trials, and cohort studies were included, and the evidence was graded according to the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) system. Consensus recommendation was reached by the group after a critical appraisal of the literature.

RESULTS

Two hundred fifty-six articles were included to develop the consensus statements for 22 ERAS items; one ERAS item (prehabilitation) was excluded from the final summary due to very poor quality and conflicting evidence in lumbar spinal fusion. From these remaining 21 ERAS items, 28 recommendations were included. All recommendations on ERAS protocol items are based on the best available evidence. These included nine preoperative, eleven intraoperative, and six postoperative recommendations. They span topics from preoperative patient education and nutritional evaluation, intraoperative anesthetic and surgical techniques, and postoperative multimodal analgesic strategies. The level of evidence for the use of each recommendation is presented.

CONCLUSION

Based on the best evidence available for each ERAS item within the multidisciplinary perioperative care pathways, the ERAS® Society presents this comprehensive consensus review for perioperative care in lumbar fusion.

Silencing matrix metalloproteinase-13 (Mmp-13) reduces inflammatory bone resorption associated with LPS-induced periodontal disease in vivo

OBJECTIVES

The aim of this study was to evaluate the effect of specific inhibition of MMP-13 on inflammation and inflammatory bone resorption in a murine model of lipopolysaccharide (LPS)-induced periodontitis.

MATERIALS AND METHODS

Periodontitis was induced in mice by micro-injections of LPS into the gingival tissues adjacent to the palatal surfaces of maxillary molars twice a week for 15 days. Matrix metalloproteinase-13 (Mmp-13) shRNA or a specific biochemical inhibitor were also injected into the same sites in alternating days with the LPS injections. Efficacy of shRNA-mediated silencing of Mmp-13 was verified by quantitative real-time polymerase chain reaction (qPCR) and immunoblot. Bone resorption was assessed by microcomputed tomography (uCT). Histological sections stained with hematoxylin/eosin (H/E) were used in the stereometric analysis of the inflammatory infiltrate. Gingival tissues were used to evaluate expression of Mmp-13, Il-6, Tnf-α, Ptgs2, and Rankl (qPCR). Protein levels of TGF-β and IL-10 in the tissues were determined by enzyme-linked immunosorbent assays (ELISA) or by MMP-13 and p38 immunoblot.

RESULTS

Silencing Mmp-13 expression reduced bone resorption significantly. Expression of Mmp-13, Il-6, and Tnf-α, as well as the protein levels of IL-6 and TNF-α, was reduced in the animals treated with adenovirus-delivered shRNA; however, these effects were not associated with modulation of p38 MAPK signaling. Interestingly, inhibition Mmp-13 did not affect the severity of inflammatory infiltrate.

CONCLUSIONS

Site-specific inhibition of MMP-13 reduced bone resorption and production of inflammatory mediators associated with periodontal disease.

CLINICAL RELEVANCE

The results suggest that site-specific inhibition of MMP-13 may be an interesting strategy to modulate inflammation and reduce bone resorption in osteolytic inflammatory diseases.

Megestrol acetate induced proliferation and differentiation of osteoblastic MC3T3-E1 cells: A drug repurposing approach

AIMS

Drug repurposing or repositioning i.e.; identifying new indications for existing drugs have recently accelerated the process of drug discovery and development. Megestrol acetate (1) is a well-known progestin. It is commonly used as an appetite stimulant, and also in the treatment of breast, and endometrial cancers. The aim of this study is to investigate the effect of megestrol acetate (1) in osteoblast differentiation, and to determine the possible mechanism involved in megestrol acetate (1) induced osteoblast differentiation.

MAIN METHODS

Cytotoxicity of different steroidal drugs was evaluated using MTT assay. Alkaline phosphatase (ALP) activity was also determined, and alizarin red S (ARS) staining was performed to measure extracellular mineralization. Osteogenic protein levels were determined using Western blot analysis.

KEY FINDINGS

Results of the current study indicated that the megestrol acetate (1) enhanced the proliferation and differentiation of osteoblast cells at 1, 0.2, and 0.04 µM. This stimulatory effect of the megestrol acetate (1) was more prominent at 0.2 µM for cell proliferation, while the maximum cell differentiation (ALPase activity, and calcification) was observed at 0.04 μM. Western blot analysis also showed that megestrol acetate (1) altered the expression of bone morphogenic protein-2 (BMP2), p38, and pJNK proteins. Hence, only moderate doses of MGA (1) can enhance osteoblast proliferation and differentiation.

SIGNIFICANCE

Our results identified that megestrol acetate (1) could be a potential lead for further research towards bone fragility related disorders.

Connexin43 enhances Wnt and PGE2-dependent activation of β-catenin in osteoblasts

Connexin43 is an important modulator of many signaling pathways in bone. β-Catenin, a key regulator of the osteoblast differentiation and function, is among the pathways downstream of connexin43-dependent intercellular communication. There are striking overlaps between the functions of these two proteins in bone cells. However, differential effects of connexin43 on β-catenin activity have been reported. Here, we examined how connexin43 influenced both Wnt-dependent and Wnt-independent activation of β-catenin in osteoblasts in vitro. Our data show that loss of connexin43 in primary osteoblasts or connexin43 overexpression in UMR106 cells regulated active β-catenin and phospho-Akt levels, with loss of connexin43 inhibiting and connexin43 overexpression increasing the levels of active β-catenin and phospho-Akt. Increasing connexin43 expression synergistically enhanced Wnt3a-dependent activation of β-catenin protein and β-catenin transcriptional activity, as well as Wnt-independent activation of β-catenin by prostaglandin E2 (PGE2). Finally, we show that the activation of β-catenin by PGE2 required signaling through the phosphatidylinositol 3-kinase (PI3K)/Akt/glycogen synthase kinase 3 beta (GSK3β) pathway, as the PI3K inhibitor, LY-294002, disrupted the synergy between connexin43 and PGE2. These data show that connexin43 regulates Akt and β-catenin activity and synergistically enhances both Wnt-dependent and Wnt-independent β-catenin signaling in osteoblasts.

The effect of non-steroidal anti-inflammatory drugs on the osteogenic activity in osseointegration: a systematic review

Non-steroidal anti-inflammatory drugs are commonly used in implant dentistry for management of post-operative pain. The objective of this systematic review was to analyse the effect of non-steroidal anti-inflammatory drugs on the osteogenic activity of osteoblasts with an emphasis on its effect on osseointegration. A systematic literature search for in vitro, animal models, and clinical trials was conducted using Ovid, PubMed, Scopus, and Web of Science databases. Articles published since the introduction of selective COX-2 inhibitors, between January 1999 and July 2018, were selected. The integrated search followed the PRISMA statement with the following key terms: non-steroidal anti-inflammatory drug/s, titanium, osseointegration, and osteoblast. The review is registered at PROSPERO database: CRD42016051448. The titles and abstracts of each research article in the initial search (n = 875) were independently screened by two reviewers. A third independent reviewer reviewed the articles that were included by one but excluded by the other reviewer. This resulted in the cataloguing of 79 full-text manuscripts where the articles were assessed for the following criteria: the study investigates the effects of NSAIDs on osteoblasts, explores the COX pathway and its effect on osteogenic activity, and compares the effects of NSAIDs on osteoblasts with a control group. A total of 13 articles have been included for qualitative synthesis. There is a lack of consensus in the literature to explicitly conclude that there is a relationship between the use of post-operative NSAIDs and failed osseointegration; however, osseointegration does not appear to be negatively affected by NSAIDs in the human clinical studies.

The Biological Enhancement of Spinal Fusion for Spinal Degenerative Disease

In this era of aging societies, the number of elderly individuals who undergo spinal arthrodesis for various degenerative diseases is increasing. Poor bone quality and osteogenic ability in older patients, due to osteoporosis, often interfere with achieving bone fusion after spinal arthrodesis. Enhancement of bone fusion requires shifting bone homeostasis toward increased bone formation and reduced resorption. Several biological enhancement strategies of bone formation have been conducted in animal models of spinal arthrodesis and human clinical trials. Pharmacological agents for osteoporosis have also been shown to be effective in enhancing bone fusion. Cytokines, which activate bone formation, such as bone morphogenetic proteins, have already been clinically used to enhance bone fusion for spinal arthrodesis. Recently, stem cells have attracted considerable attention as a cell source of osteoblasts, promising effects in enhancing bone fusion. Drug delivery systems will also need to be further developed to assure the safe delivery of bone-enhancing agents to the site of spinal arthrodesis. Our aim in this review is to appraise the current state of knowledge and evidence regarding bone enhancement strategies for spinal fusion for degenerative spinal disorders, and to identify future directions for biological bone enhancement strategies, including pharmacological, cell and gene therapy approaches.

The effect of NSAIDs on spinal fusion: a cross-disciplinary review of biochemical, animal, and human studies

PURPOSE

Non-steroidal anti-inflammatory drugs (NSAIDs) play an important role in postoperative pain management. However, their use in the setting of spine fusion surgery setting has long been a topic of controversy. In this review we examined relevant research, including in vivo, animal, and clinical human studies, with the aim of understanding the effect of NSAIDs on spinal fusion.

STUDY DESIGN/SETTING

Systematic review of study designs of all types from randomized controlled trials and meta-analyses to single-institution retrospective reviews.

METHODS

A search of PubMed and Embase was conducted using the keywords: "spine," "spinal fracture," NSAIDs, anti-inflammatory non-steroidal agents, bone, bone healing, fracture, fracture healing, yielding a total of 110 studies. Other 28 studies were identified by cross-referencing, resulting in total 138 studies.

RESULTS

There is no level I evidence from human studies regarding the use of NSAIDs on spinal fusion rates. The overall tone of the spine literature in the early 2000s was that NSAIDs increased the rate of non-union; however, nearly all human studies published after 2005 suggest that short-term (<2 weeks) postoperative use have no such effect. The dose dependency that is seen with a 2-week postoperative course is not present when NSAIDs are only used for 48 h after surgery.

CONCLUSIONS

NSAID appear to have dose-dependent and duration-dependent effects on fusion rates. The short-term use of low-dose NSAIDs around the time of spinal fusion surgery is reasonable. Spine surgeons can consider the incorporation of NSAIDs into pain control regimens for spinal fusion patients with the goal of improving pain control and reducing the costs and complications associated with opioids.

Odontogenic epithelial proliferation is correlated with COX-2 expression in dentigerous cyst and ameloblastoma

Investigation of cyclooxygenase (COX)-2 in dentigerous cyst and ameloblastoma may help to improve understanding of the nature and behavior of odontogenic cysts and tumors, and in addition may eventually represent a definitive target for a pharmacological approach in the management of these lesions. The aim of this study was to evaluate COX-2 expression and its correlation with the proliferation of odontogenic epithelium in these lesions. Dentigerous cysts (n=16) and ameloblastomas (n=17) were evaluated. Detection of Ki-67 and COX-2 protein expression was conducted by immunohistochemistry. Data were statistically analyzed using Mann-Whitney U test and Spearman's rank correlation coefficient. No significant differences were found in the expression of Ki-67 and COX-2 between dentigerous cysts and ameloblastomas (P>0.05). A significant positive correlation (P=0.018) and highly significant positive correlation (P=0.004) were found between Ki-67 and COX-2 expression in the odontogenic epithelium of dentigerous cyst and ameloblastoma, respectively. COX-2 was expressed in the odontogenic epithelium of dentigerous cyst and ameloblastoma. It may contribute to local extension of these lesions by increasing the proliferation of their odontogenic epithelial cells.

Meloxicam temporally inhibits the expression of vascular endothelial growth factor receptor (VEGFR)-1 and VEGFR-2 during alveolar bone repair in rats

BACKGROUND

Vascular endothelial growth factor (VEGF) plays an important role during angiogenesis and bone repair. This study investigated whether the use of meloxicam alters bone repair via downregulation of VEGF and receptor expression.

METHODS

One hundred twenty male Wistar rats had their maxillary right incisor extracted. Animals were divided into a control group (CG; n = 60) and a meloxicam-treated group (TG; n = 60) that received either a single daily intraperitoneal injection of 0.9% NaCl or meloxicam 3 mg/kg, respectively, for 7 consecutive days. Alveolar bone repair was evaluated histomorphometrically, whereas VEGF and its receptors were analyzed by immunohistochemistry and quantitative polymerase chain reaction (qPCR). Data were submitted to two-way analysis of variance and Tukey post hoc test with P < 0.05.

RESULTS

Bone volume density increased significantly (P = 0.001) in both groups with a strong correlation between treatment and periods (P = 0.003). In the TG, a small amount of bone formation occurred compared with the CG between 3 and 21 days. No significant differences in the number of VEGF-positive cells per square millimeter (P = 0.07) and VEGF messenger RNA (mRNA) expression (P = 0.49) were found between groups. Immunostained cells per square millimeter and mRNA expression for VEGF receptor (VEGFR)-1 (P = 0.04 and P < 0.001) and VEGFR-2 (P < 0.001 for both analysis) showed a strong interaction between treatment groups and periods. In the TG, immunostained cells per square millimeter and mRNA expression for VEGFR-1 were, respectively, 89% and 37% lower from 3 to 10 days compared with the CG, whereas for VEGFR-2, these values were 252% and 60%, respectively, from 3 to 7 days.

CONCLUSION

In rat alveolar bone repair, meloxicam did not affect VEGF expression but downregulated VEGFR expression, which may cause a delay in the bone repair/remodeling process.

Effects of Nonsteroidal Anti-inflammatory Drugs on Osseointegration: A Review

The purpose of this study was to review the effects of nonsteroidal anti-inflammatory drugs on osseointegration and determine whether they cause failures in dental implants and whether patients who use them chronically can receive dental implants safely. A bibliographic electronic search was performed using the Cochrane Library, PubMed, and Medline databases, selecting articles published between January 1982 and December 2012. The search included the following keywords, either alone or combined: “nonsteroidal anti-inflammatory drugs,” “dental implants,” “bone healing,” and “osteoprogenitor cells.” The inclusion criteria were the following: randomized, double-blind, placebo-controlled clinical studies, in vivo animal model studies of osseointegration, and in vitro studies of the effects of these agents on osteoprogenitor cells. The literature search revealed 360 references. A total of 31 articles met the inclusion criteria, including 2 clinical trials, 20 animal studies, and 9 osteoprogenitor cell studies. The clinical trials revealed that cyclooxygenase-1 (COX-1) inhibitors did not impair osseointegration. The animal studies showed that any drug that is capable of inhibiting COX-2 may impair the osseointegration process. The in vitro studies showed that COX-2 inhibitors are the most potent depressors of osseointegration at the cellular level. Caution must be taken when selecting COX-2 nonsteroidal anti-inflammatory drugs during the postoperative period.

Repercussions of NSAIDS drugs on bone tissue: the osteoblast

Non-steroidal anti-inflammatory drugs (NSAIDs) can act by modulating the behavior of osteoblasts, including their proliferation, differentiation, adhesion, and migration, but not all NSAIDs have these effects. Our objective was to update the information on this issue in a review of the literature in order to offer guidance on the prescription of the appropriate NSAID(s) to patients requiring bone tissue repair. To review current knowledge of this issue by searching for all relevant publications since 2001 in the MEDLINE, EMBASE and Cochrane Library databases, we used the following descriptors: bone tissue, osteoblast, NSAIDs, Anti-inflammatory drugs. Published studies show that most NSAIDs have an adverse effect on osteoblast growth by cell cycle arrest and apoptosis induction. The effect on differentiation varies according to the drug, dose, and treatment time. Osteoblast adhesion is increased and migration decreased by some NSAIDs, such as indomethacin and diclofenac. The antigenic profile or phagocytic function can also be modulated by NSAIDs. In general, NSAIDs have an adverse effect on bone tissue and given the routine administration of NSAIDs to individuals requiring bone repair, in which the osteoblast has an essential role, this effect on bone should be borne in mind.

Alzheimer's disease and chronic periodontitis: is there an association?

Alzheimer's disease, an affliction of old age, is one of the leading causes for dementia worldwide. Various risk factors including family history, genetics and infections have been implicated in its pathogenesis. The cognitive decline in this condition is mainly a result of the formation of amyloid deposits that provoke neuroinflammation, ultimately resulting in cell death. Recently, an association between peripheral inflammation and Alzheimer's disease was hypothesized. It was suggested that chronic systemic inflammation worsened the inflammatory processes in the brain. This was mainly attributed to increased levels of pro-inflammatory mediators, such as interleukin-1, interleukin -6 and tumor necrosis factor-α in the plasma. As chronic periodontitis is a widespread peripheral immunoinflammatory condition, it has been proposed to play a significant role in the aggravation of Alzheimer's disease. With this background, the current review focuses on the relationship between Alzheimer's disease and chronic periodontitis, and its therapeutic implications.

Perioperative use of non-steroidal anti-inflammatory drugs might impair dental implant osseointegration

OBJECTIVE

To appraise whether adverse biological events following oral implant placement may be associated with perioperative use of non-steroidal anti-inflammatory drugs (NSAIDs).

METHODS

All patients treated in a university faculty postgraduate dental clinic between 1979 and 2012 that had experienced a failing and surgically removed dental implant (292 implants in 168 patients) were contacted to solicit additional information about their present dental and medical status and frequency of current and past use of NSAIDs. Potential associations between perioperative NSAIDs use and the occurrence of adverse biological events were explored by the use of 2 × 2 tables and two-tailed Fisher's exact tests.

RESULTS

One hundred and four patients with initially 468 implants had experienced 238 implant failures, of which 197 were due to failing osseointegration (42%). Sixty of the participants, initially with 273 implants, had used NSAIDs perioperatively and experienced 44% implant failures, versus 38% in the non-NSAID cohort. The NSAID cohort experienced 3.2 times more cases of radiographic bone loss greater than 30% of the vertical height of their remaining implants and 1.9 times more cases of cluster failures, defined as failure of 50% or more of the implant(s) placed.

CONCLUSIONS

Notwithstanding that a retrospective study design is open to potential bias, the current data indicate that dental implant osseointegration may be affected negatively by an inhibitory effect of NSAIDs on bone healing in vulnerable patients. Future and better clinical studies than the current should be designed to appraise more precisely the potential effects of NSAIDs on implant osseointegration in study populations that are not limited by stringent medical inclusion and exclusion criteria.

Expression of human papillomavirus is correlated with Ki-67 and COX-2 expressions in keratocystic odontogenic tumor

The aim of the current study was to investigate the presence of human papillomavirus (HPV) and evaluate its association with Ki-67 and cyclooxygenase-2 (COX-2) expressions in keratocystic odontogenic tumor (KCOT). Nineteen cases were included in the present study. Conventional PCR method and immunohistochemical analysis were performed for the detection of HPV-DNA and HPV-L1 capsid protein. Moreover, the expressions of Ki-67 and COX-2 proteins were analyzed immunohistochemically. HPV-DNA was detected in 36.8% (7/19) of tumor samples, whilst HPV-L1 protein was identified in 68.4% (13/19) of them. The Kappa coefficient statistical test showed a moderate agreement (κ 0.424) between PCR and IHC assays for HPV detection. Expression of HPV-DNA was positively correlated with Ki-67 and COX-2 expressions (p < 0.05), whereas HPV-L1 positive staining was positively correlated with COX-2 (p < 0.05) and highly associated with those of Ki-67 (p < 0.01). There was no significant correlation between the presence of HPV and the recurrence of the studied lesions. The results of the current study showed that active HPV infection was present in the odontogenic epithelium of KCOT, and it was associated with increased proliferation rate and COX-2 expression. These findings suggest that HPV may have a role in the pathogenesis and aggressiveness of KCOT. Based on these conclusions, we recommend further investigations of HPV vaccine or antiviral therapy and COX-2 inhibitors as nonsurgical options in the prevention and management of KCOT.

The role of osteoimmunology in periodontal disease

Periodontal disease is a pathological condition that involves inflammation of the tooth supporting structures. It occurs in response to the presence of bacterial plaque on the tooth structure. The host defense system, including innate and adaptive immunity, is responsible for combating the pathologic bacteria invading the periodontal tissue. Failure to eradicate the invading pathogens will result in a continuous state of inflammation where inflammatory cells such as lymphocytes, PMNs, and macrophages will continue to produce inflammatory mediators in an effort to destroy the invaders. Unfortunately, these inflammatory mediators have a deleterious effect on the host tissue as well as foreign microbes. One of the effects of these mediators on the host is the induction of matrix degradation and bone resorption through activation of proteases and other inflammatory mediators that activate osteoclasts.

T cell replicative senescence in human aging

The decline of the immune system appears to be an intractable consequence of aging, leading to increased susceptibility to infections, reduced effectiveness of vaccination and higher incidences of many diseases including osteoporosis and cancer in the elderly. These outcomes can be attributed, at least in part, to a phenomenon known as T cell replicative senescence, a terminal state characterized by dysregulated immune function, loss of the CD28 costimulatory molecule, shortened telomeres and elevated production of proinflammatory cytokines. Senescent CD8 T cells, which accumulate in the elderly, have been shown to frequently bear antigen specificity against cytomegalovirus (CMV), suggesting that this common and persistent infection may drive immune senescence and result in functional and phenotypic changes to the T cell repertoire. Senescent T cells have also been identified in patients with certain cancers, autoimmune diseases and chronic infections, such as HIV. This review discusses the in vivo and in vitro evidence for the contribution of CD8 T cell replicative senescence to a plethora of age-related pathologies and a few possible therapeutic avenues to delay or prevent this differentiative end-state in T cells. The age-associated remodeling of the immune system, through accumulation of senescent T cells has farreaching consequences on the individual and society alike, for the current healthcare system needs to meet the urgent demands of the increasing proportions of the elderly in the US and abroad.

Inflammatory mediators in the pathogenesis of periodontitis

Periodontitis is a chronic inflammatory condition of the periodontium involving interactions between bacterial products, numerous cell populations and inflammatory mediators. It is generally accepted that periodontitis is initiated by complex and diverse microbial biofilms which form on the teeth, i.e. dental plaque. Substances released from this biofilm such as lipopolysaccharides, antigens and other virulence factors, gain access to the gingival tissue and initiate an inflammatory and immune response, leading to the activation of host defence cells. As a result of cellular activation, inflammatory mediators, including cytokines, chemokines, arachidonic acid metabolites and proteolytic enzymes collectively contribute to tissue destruction and bone resorption. This review summarises recent studies on the pathogenesis of periodontitis, with the main focus on inflammatory mediators and their role in periodontal disease.

T cell replicative senescence in human aging

The decline of the immune system appears to be an intractable consequence of aging, leading to increased susceptibility to infections, reduced effectiveness of vaccination and higher incidences of many diseases including osteoporosis and cancer in the elderly. These outcomes can be attributed, at least in part, to a phenomenon known as T cell replicative senescence, a terminal state characterized by dysregulated immune function, loss of the CD28 costimulatory molecule, shortened telomeres and elevated production of proinflammatory cytokines. Senescent CD8 T cells, which accumulate in the elderly, have been shown to frequently bear antigen specificity against cytomegalovirus (CMV), suggesting that this common and persistent infection may drive immune senescence and result in functional and phenotypic changes to the T cell repertoire. Senescent T cells have also been identified in patients with certain cancers, autoimmune diseases and chronic infections, such as HIV. This review discusses the in vivo and in vitro evidence for the contribution of CD8 T cell replicative senescence to a plethora of age-related pathologies and a few possible therapeutic avenues to delay or prevent this differentiative end-state in T cells. The age-associated remodeling of the immune system, through accumulation of senescent T cells has farreaching consequences on the individual and society alike, for the current healthcare system needs to meet the urgent demands of the increasing proportions of the elderly in the US and abroad.

Do nonsteroidal anti-inflammatory drugs affect bone healing? A critical analysis

Nonsteroidal anti-inflammatory drugs (NSAIDs) play an essential part in our approach to control pain in the posttraumatic setting. Over the last decades, several studies suggested that NSAIDs interfere with bone healing while others contradict these findings. Although their analgesic potency is well proven, clinicians remain puzzled over the potential safety issues. We have systematically reviewed the available literature, analyzing and presenting the available in vitro animal and clinical studies on this field. Our comprehensive review reveals the great diversity of the presented data in all groups of studies. Animal and in vitro studies present so conflicting data that even studies with identical parameters have opposing results. Basic science research defining the exact mechanism with which NSAIDs could interfere with bone cells and also the conduction of well-randomized prospective clinical trials are warranted. In the absence of robust clinical or scientific evidence, clinicians should treat NSAIDs as a risk factor for bone healing impairment, and their administration should be avoided in high-risk patients.

Treatment with paracetamol, ketorolac or etoricoxib did not hinder alveolar bone healing: a histometric study in rats

Prostaglandins control osteoblastic and osteoclastic function under physiological or pathological conditions and are important modulators of the bone healing process. The non-steroidal anti-inflammatory drugs (NSAIDs) inhibit cyclooxygenase (COX) activity and consequently prostaglandins synthesis. Experimental and clinical evidence has indicated a risk for reparative bone formation related to the use of non-selective (COX-1 and COX-2) and COX-2 selective NSAIDs. Ketorolac is a non-selective NSAID which, at low doses, has a preferential COX-1 inhibitory effect and etoricoxib is a new selective COX-2 inhibitor. Although literature data have suggested that ketorolac can interfere negatively with long bone fracture healing, there seems to be no study associating etoricoxib with reparative bone formation. Paracetamol/acetaminophen, one of the first choices for pain control in clinical dentistry, has been considered a weak anti-inflammatory drug, although supposedly capable of inhibiting COX-2 activity in inflammatory sites.

Effects of long-term administration of carprofen on healing of a tibial osteotomy in dogs

OBJECTIVE

To evaluate effects of long-term administration of carprofen on healing of a tibial osteotomy in dogs.

ANIMALS

12 healthy female Beagles.

PROCEDURES

A mid-diaphyseal transverse osteotomy (stabilized with an intramedullary pin) of the right tibia was performed in each dog. The carprofen group (n = 6 dogs) received carprofen (2.2 mg/kg, PO, q 12 h) for 120 days; the control group (6) received no treatment. Bone healing and change in callus area were assessed radiographically over time. Dogs were euthanized 120 days after surgery, and tibiae were evaluated biomechanically and histologically.

RESULTS

The osteotomy line was not evident in the control group on radiographs obtained 120 days after surgery. In contrast, the osteotomy line was still evident in the carprofen group. Callus area was significantly less in the carprofen group, compared with the area in the control group, at 20, 30, and 60 days after surgery. At 120 days after surgery, stiffness, elastic modulus, and flexural rigidity in the carprofen group were significantly lower than corresponding values in the control group. Furthermore, histologic evaluation revealed that the cartilage area within the callus in the carprofen group was significantly greater than that in the control group.

CONCLUSIONS AND CLINICAL RELEVANCE

Long-term administration of carprofen appeared to inhibit bone healing in dogs that underwent tibial osteotomy. We recommend caution for carprofen administration when treating fractures that have delays in healing associated with a reduction in osteogenesis as well as fractures associated with diseases that predispose animals to delays of osseous repair.

Histometric study of alveolar bone healing in rats treated with the nonsteroidal anti-inflammatory drug nimesulide

PURPOSE

There is extensive experimental and clinical evidence in the orthopedic area that prolonged use of nonselective (inhibitor of both cyclooxygenases 1 and 2) nonsteroidal anti-inflammatory drugs can hinder long bone fracture healing, spinal fusion rate, and new bone formation around implants. The purpose of the present study was to investigate whether nimesulide (Nimesulida, Medley S.A., Campinas, SP, Brazil), a preferential cyclooxygenase-2 inhibitor, can hinder alveolar bone healing, in rats.

MATERIALS AND METHODS

Treated rats received oral doses (5 mg/kg/rat/day) of nimesulide from the day of tooth extraction until euthanasia 2 weeks later and control rats received tap water (n = 5 per group). The volume of neoformed bone inside the alveolar socket was estimated in semiserial longitudinal histological sections by a differential point-counting method, and the significance of the difference between groups was analyzed by Student t test (P < 0.05 for statistical significance).

RESULTS

Histometric data confirmed histological observation that the volume fraction of new bone trabeculae in treated rats was not significantly different from that in control rats.

CONCLUSION

Short-term treatment with nimesulide, although its capacity to inhibit preferentially the enzyme cyclooxygenase-2, does not interfere with alveolar bone healing in rats.

Caffeine enhances osteoclast differentiation from bone marrow hematopoietic cells and reduces bone mineral density in growing rats

Caffeine-containing beverage consumption has been associated with low bone mass and increased fracture risk in some, but not most, observational studies. The effects of caffeine on bone metabolism are still controversial. We investigated the effects of caffeine on the differentiation of bone progenitor cells and bone mineral density (BMD) by in vitro and in vivo experiments. Low-concentration caffeine (0.005-0.1 mM) did not affect the bone marrow cell viability and alkaline phosphatase activity during osteoblast differentiation from bone marrow stromal cells, but it effectively enhanced the osteoclastogenesis from bone marrow hematopoietic cells and the bone resorption activity by pit formation assay. Moreover, caffeine effectively enhanced the receptor activator of NF-κB ligand (RANKL), but reduced the osteoprotegerin protein expressions in osteoblast MC3T3-E1 cells. Caffeine could also increase the cyclooxygenase-2 (COX-2) protein expression and prostaglandin (PG)E(2) production in cultured neonatal mouse calvariae. In animal study, BMD in lumbar vertebra, femur, or tibia was significantly lowered in growing rats supplemented with 0.2% caffeine in diets for 20 weeks compared with the control group. The calcium contents in tibia and femur of caffeine-treated rats were also lower than that in the control group. The osteoclastogenesis of bone marrow cells isolated from caffeine-treated rats was markedly enhanced as compared with the control group. Taken together, these results suggest that caffeine may reduce BMD in growing rats through the enhancement in osteoclastogenesis. Caffeine may possess the ability to enhance a COX-2/PGE(2) -regulated RANKL-mediated osteoclastogenesis.

Stability changes of miniscrew implants over time

PURPOSE

To quantify in vivo changes in miniscrew implant (MSI) stability over time using resonance frequency analysis, and to determine if pilot holes and placement sites affect changes in MSI stability.

MATERIALS AND METHODS

Twenty-two self-tapping MSIs (1.6 mm wide and 9 mm long) were placed in the maxillae of 2 adult beagle dogs (20 months old). The Osstell Mentor was used to measure the implant stability quotient (ISQ) weekly for 8 weeks. A split-mouth design was used to evaluate the effects of 1.1-mm wide, 3-mm deep pilot holes.

RESULTS

The MSIs that failed showed significantly (P < .05) greater decreases in ISQ values during the first 3 weeks than the MSIs that remained stable. All of the MSIs that failed (41%) had been placed in nonkeratinized tissue. MSIs that remained stable throughout the study also showed significant decreases in ISQ values during the first 3 weeks, followed by increases during the fourth and fifth weeks. Changes in ISQ values of MSIs inserted into bone with and without pilot holes were comparable (P > .05).

CONCLUSION

Stability of unloaded MSIs decreased during the first 3 weeks and increased thereafter. Although the effects of pilot holes on stability could not be confirmed, placement of MSIs into nonkeratinized tissue negatively affected their stability and increased the likelihood of failures.

Sodium butyrate induces the production of cyclooxygenases and prostaglandin E₂ in ROS 17/2.8 osteoblastic cells

OBJECTIVE

Sodium butyrate (butyric acid; BA) is a major metabolic by-product of the anaerobic periodontopathic bacteria present in subgingival plaque. We examined the effects of BA and/or indomethacin on cell proliferation, the expression of cyclooxygenases (COXs), prostaglandin (PG) receptors (EP1-4), extracellular matrix proteins, such as type I collagen and osteopontin, and PGE(2) production, using ROS17/2.8 cells as osteoblasts.

METHODS

The rat clonal cell line ROS 17/2.8 was cultured with 0, 10(-5), 10(-4), and 10(-3)M BA in the presence or absence of 0.5 μM indomethacin, for up to 7 days. The expression of COX-1, COX-2, EP1, EP2, EP3, EP4, type I collagen, and osteopontin was examined at the mRNA and protein levels using real-time PCR and Western blotting, respectively. The amount of PGE(2) in the culture medium was measured by ELISA.

RESULTS

Proliferation of ROS 17/2.8 cells was not affected by the addition of BA. However, PGE(2) production and the expression of COX-1 and COX-2 increased with the addition of BA. In contrast, indomethacin, an inhibitor of COX, blocked the stimulatory effect of BA. Furthermore, EP2 expression increased with BA treatment, whereas EP1 expression was not affected and the expression of EP3 and EP4 was not detected. The addition of BA also increased the expression of type I collagen and osteopontin. Indomethacin blocked about 50% of the stimulatory effect of BA on type I collagen, whereas it did not block the effect on osteopontin.

CONCLUSIONS

These results suggest that BA induces PGE(2) production by increasing the expression of COX-1 and COX-2 in osteoblasts, and that an autocrine action of the produced PGE(2), via EP1 or BA-induced EP2, is related to an increase in type I collagen expression by BA.

Review of osteoimmunology and the host response in endodontic and periodontal lesions

Both lesions of endodontic origin and periodontal diseases involve the host response to bacteria and the formation of osteolytic lesions. Important for both is the upregulation of inflammatory cytokines that initiate and sustain the inflammatory response. Also important are chemokines that induce recruitment of leukocyte subsets and bone-resorptive factors that are largely produced by recruited inflammatory cells. However, there are differences also. Lesions of endodontic origin pose a particular challenge since that bacteria persist in a protected reservoir that is not readily accessible to the immune defenses. Thus, experiments in which the host response is inhibited in endodontic lesions tend to aggravate the formation of osteolytic lesions. In contrast, bacteria that invade the periodontium appear to be less problematic so that blocking arms of the host response tend to reduce the disease process. Interestingly, both lesions of endodontic origin and periodontitis exhibit inflammation that appears to inhibit bone formation. In periodontitis, the spatial location of the inflammation is likely to be important so that a host response that is restricted to a subepithelial space is associated with gingivitis, while a host response closer to bone is linked to bone resorption and periodontitis. However, the persistence of inflammation is also thought to be important in periodontitis since inflammation present during coupled bone formation may limit the capacity to repair the resorbed bone.

High-fat, sucrose diet impairs geometrical and mechanical properties of cortical bone in mice

Exposure to diets high in fat and sucrose can induce hyperinsulinaemia, affect Ca and Mg metabolism, and alter bone mineralisation and mechanical properties. The present study assessed morphological and mechanical changes in a murine model exposed to a high-fat/sucrose (HFS) diet, as well as corresponding molecular and endocrine markers of bone turnover. Female C57BL/6 mice (aged 9 weeks) consumed either a low-fat, complex carbohydrate diet or an HFS diet for 10 weeks. At the end of the 10 weeks, serum was collected for biochemical analysis. Tibiae from half the mice (n 15) were randomly selected to be micro-computed tomography scanned and tested to failure in cantilever bending, while the remaining half were prepared for real-time PCR analysis. Serum tartrate-resistant acid phosphatase was significantly elevated in HFS mice, while osteocalcin remained unchanged. Both body mass and percentage body fat were greater in mice fed HFS diet. After adjusting for body mass, tibial structural and morphological properties were adversely affected in the HFS cohort. Cortical thickness, cross-sectional area, and load at maximum were all significantly lower in mice fed HFS diet. Receptor activator of nuclear factor kappabeta ligand (RANKL) mRNA was significantly upregulated in HFS mice, but osteoprotegerin/RANKL mRNA ratio remained unchanged between cohorts. Moreover, cyclo-oxygenase-2 mRNA tended to be increased in HFS. Thus, ingestion of an HFS diet had a significant adverse effect on mouse bone morphology and mechanics, and these effects were likely due to elevated osteoclast activity associated with the inflammatory state of obesity, and not necessarily osteoclast recruitment/proliferation.