Fungal footprints in oral cancer: unveiling the oral mycobiome.

Oral squamous cell carcinoma (OSCC) is the most common type of head and neck cancer, with a high mortality rate. There is growing evidence supporting a link between oral cancer and the microbiome. The microbiome can impact various aspects of cancer, such as pathogenesis, diagnosis, treatment, and prognosis. While there is existing information on bacteria and its connection to oral cancer, the fungi residing in the oral cavity represent a significant component of the microbiome that remains in its early stages of exploration and understanding. Fungi comprise a minuscule part of the human microbiome called the mycobiome. Mycobiome is ubiquitous in the human body but a weakened immune system offers a leeway space for fungi to showcase its virulence. The role of mycobiome as a colonizer, facilitator, or driver of carcinogenesis is still ambiguous. Reactivating the mycobiome that undergoes collateral damage associated with cancer treatment can be watershed event in cancer research. The coordinated, virulent, non-virulent behavior of the fungi once they reach a critical density must be hacked, considering its diagnostic, prognostic and therapeutic implications in cancer. This review highlights the diversity of the mycobiome and its potential role in oral cancer.

Targeting phosphatidylinositol-3-kinase for inhibiting maxillary bone resorption.

Previous studies have suggested a role of phosphatidylinositol-3-kinase gamma (PI3Kγ) in bone remodeling, but the mechanism remains undefined. Here, we explored the contribution of PI3Kγ in the resorption of maxillary bone and dental roots using models of orthodontic tooth movement (OTM), orthodontic-induced inflammatory root resorption, and rapid maxillary expansion (RME). PI3Kγ-deficient mice (PI3Kγ-/- ), mice with loss of PI3Kγ kinase activity (PI3KγKD/KD ) and C57BL/6 mice treated with a PI3Kγ inhibitor (AS605240) and respective controls were used. The maxillary bones of PI3Kγ-/- , PI3KγKD/KD , and C57BL/6 mice treated with AS605240 showed an improvement of bone quality compared to their controls, resulting in reduction of the OTM and RME in all experimental groups. PI3Kγ-/- mice exhibited increased root volume and decreased odontoclasts counts. Consistently, the pharmacological blockade or genetic deletion of PI3K resulted in increased numbers of osteoblasts and reduction in osteoclasts during OTM. There was an augmented expression of Runt-related transcription factor 2 (Runx2) and alkaline phosphatase (Alp), a reduction of interleukin-6 (Il-6), as well as a lack of responsiveness of receptor activator of nuclear factor kappa-Β (Rank) in PI3Kγ-/- and PI3KγKD/KD mice compared to control mice. The maxillary bones of PI3Kγ-/- animals showed reduced p-Akt expression. In vitro, bone marrow cells treated with AS605240 and cells from PI3Kγ-/- mice exhibited significant augment of osteoblast mineralization and less osteoclast differentiation. The PI3Kγ/Akt axis is pivotal for bone remodeling by providing negative and positive signals for the differentiation of osteoclasts and osteoblasts, respectively.

Spermidine Suppresses Oral Carcinogenesis through Autophagy Induction, DNA Damage Repair, and Oxidative Stress Reduction.

Autophagy has been proposed to play a dual role in cancer-as a tumor suppressor in early stages and oncogenic in late stages of tumorigenesis. This study investigated the role of autophagy in oral carcinogenesis using the model of oral squamous cell carcinoma (OSCC) induced by carcinogen 4-nitroquinoline 1-oxide (4NQO), mimicking molecular and histopathologic aspects of human OSCC. The induction of autophagy by spermidine (SPD) treatment reduced the severity of lesions and the incidence of OSCC in mice exposed to 4NQO. On the other hand, autophagy inhibition by chloroquine treatment had no protection. The comet assay indicated that SPD reduced 4NQO-induced DNA damage, likely related to the activation of DNA repair and the decrease of reactive oxygen species. As sphingolipid alterations have been reported in OSCC, sphingolipids in the tongue and plasma of animals were analyzed and plasma C16 ceramide levels were shown to increase proportionally to lesion severity, indicating its potential as a biomarker. Mice exposed to 4NQO plus SPD had lower levels of C16 ceramide than the 4NQO group, which indicated SPD's ability to prevent the 4NQO-induced carcinogenesis. Together, these data indicate that activation of autophagy has a tumor suppressor role during the early stages of oral carcinogenesis. Because of its ability to induce autophagy accompanied by reduced oxidative stress and DNA damage, SPD may have a protective action against chemically induced oral cancer.

Protective Effect of Virgin Coconut Oil on Osteopenia Induced by High Refined Carbohydrate-Containing Diet in Mice.

BACKGROUND: Obesity leads to chronic low-grade inflammation, promoting detrimental effects on bone. The consumption of virgin coconut oil (VCO) is associated with benefits related to meta-inflammation. We evaluated the effect of VCO supplementation on osteopenia promoted by diet-induced obesity in mice. METHODS: Male BALB/c mice were fed a control (C) or highly refined carbohydrate-containing (HC) diet for eight weeks. After that, the HC diet group was supplemented with three doses of VCO for four weeks. RESULTS: The HC diet increased the adiposity and leptin levels associated with augmented systemic inflammatory cells improved with VCO supplementation. The HC diet reduced the trabecular bone in the tibia, lumbar vertebrae, distal and proximal femur, as well as the bone mineral density of the femur and alveolar bone. The VCO supplementation reverted bone osteopenia by increasing the trabecular bone in different sites and improving femur and alveolar bone microarchitecture. Although the reduced number of osteoblasts in the alveolar bone of the HC diet group was not significantly enhanced by VCO supplementation, the reduced Alp expression in the HC diet group was enhanced in the VCO group. These beneficial effects were associated with lowering the Rankl/Opg ratio. CONCLUSION: VCO supplementation might be an effective strategy to attenuate bone osteopenic effects induced by obesity.

Hemorrhagic complications in individuals with liver disease submitted to minor oral surgery.

Individuals with chronic liver disease (CLD) have an increased risk of bleeding from thrombocytopenia and changes in hemostasis. The aim of this study was to evaluate the frequency of and the factors associated with the occurrence of bleeding in CLD patients who underwent dental surgical procedures. This was a retrospective study whose data were collected in a hospital dentistry service between 2010 and 2016. The patients were referred from the gastroenterology and liver transplantation services of a university hospital for dental treatment. The study followed the STROBE guidelines. Among the 71 surgical procedures performed, there were 17 (24%) perioperative and postoperative bleeding episodes, 14 of which were in pretransplant patients and 11 received blood transfusion before dental surgery. Individuals with a previous history of bleeding (PR = 2.67, CI = 1.07-6.67, P  = 0.035) and those with a platelet count before surgery 50 × 10 9 /l or less (PR = 7.48, CI = 1.70-32.86, P  = 0.008) had a higher prevalence of perioperative and postoperative bleeding episodes than their peers without a previous history of bleeding, and those with platelet count greater than 50 × 10 9 /l. The approach to individuals with CLD is complex and represents a challenge to the clinician. A careful anamnesis combined with laboratory screening of coagulation disorders appears to be useful to identify individuals at a major risk of bleeding. Studies identifying the predisposing factors of bleeding in CLD patients support well tolerated protocols for oral surgery in this group.

Interplay between epithelial and mesenchymal cells unveils essential proinflammatory and pro-resolutive mediators modulated by photobiomodulation therapy at 660 nm.

Photobiomodulation therapy (PBMT) has been widely used to promote tissue repair. However, PBMT's critical roles in the epithelial and mesenchymal tissues interactions are still barely known. Herein, we investigated light parameters on challenged keratinocytes (KC)-i.e., cultivated under oxidative stress-solely or associated with fibroblasts (FB) in a co-culture system. Cells were treated with PBMT at the wavelength of 660 nm, at 20 mW and 0.71 W/cm2 . Three different energy densities were primarily evaluated on KC: 1 (1.4 s), 5 (7 s), and 50 J/cm2 (70 s). Next, KC and FB were co-cultured and assessed at 5 J/cm2 . This energy density was also tested in ex vivo murine skin samples. Our main data suggest that PBMT can increase cellular proliferation at low doses and cell migration in a biphasic mode (1 and 50 J/cm2 ), both further confirmed by the epidermal growth factor receptor ligand-amphiregulin-upregulation. IL-1RA mRNA-the IL-1ß (interleukin-1ß) receptor antagonist recognized to fasten wound repair-was upregulated in the co-culture system. Upon PBMT, the ex vivo findings showed a progressive increase in the epidermal thickness, although presenting qualitatively less differentiated epithelium than the control group. In conclusion, PBMT effects are dependent on the cellular interactions with the surrounding microenvironment. Ultimately, PBMT is anti-inflammatory and contributes to the expression of critical mediators of wound repair.

Eosinophil plays a crucial role in intestinal mucositis induced by antineoplastic chemotherapy.

Mucositis is a major clinical complication associated with cancer treatment and may limit the benefit of chemotherapy. Leukocytes and inflammatory mediators have been extensively associated with mucositis severity. However, the role of eosinophils in the pathophysiology of chemotherapy-induced mucositis remains to be elucidated. Here, using GATA-1-deficient mice, we investigated the role of eosinophils in intestinal mucositis. There was marked accumulation of eosinophils in mice given irinotecan and eosinophil ablation inhibited intestinal mucositis. Treatment with Evasin-4, a chemokine receptor antagonist, reduced the recruitment of eosinophils and decreased irinotecan-induced mucositis. Importantly, Evasin-4 did not interfere negatively with the antitumour effects of irinotecan. Evasin-4 was of benefit for mice given high doses of irinotecan once Evasin-4-treated mice presented delayed mortality. Altogether, our findings suggest that Evasin-4 may have significant mucosal-protective effects in the context of antineoplastic chemotherapy and may, therefore, be useful in combination with anticancer treatment in cancer patients.

Cigarette smoke induces miR-132 in Th17 cells that enhance osteoclastogenesis in inflammatory arthritis.

Rheumatoid arthritis (RA) is a chronic inflammatory disease characterized by joint destruction and severe morbidity. Cigarette smoking (CS) can exacerbate the incidence and severity of RA. Although Th17 cells and the Aryl hydrocarbon receptor (AhR) have been implicated, the mechanism by which CS induces RA development remains unclear. Here, using transcriptomic analysis, we show that microRNA-132 is specifically induced in Th17 cells in the presence of either AhR agonist or CS-enriched medium. miRNA-132 thus induced is packaged into extracellular vesicles produced by Th17 and acts as a proinflammatory mediator increasing osteoclastogenesis through the down-regulation of COX2. In vivo, articular knockdown of miR-132 in murine arthritis models reduces the number of osteoclasts in the joints. Clinically, RA patients express higher levels of miR-132 than do healthy individuals. This increase is further elevated by cigarette smoking. Together, these results reveal a hitherto unrecognized mechanism by which CS could exacerbate RA and further advance understanding of the impact of environmental factors on the pathogenesis of chronic inflammatory diseases.

Direct oral anticoagulants in oral surgery: a prospective cohort.

BACKGROUND: Quantitative assessment of bleeding in dental extractions is rarely reported in the literature. The assessment of bleeding might provide additional evidence to predict and minimize postoperative outcomes. The aim of this study was to evaluate the pattern of bleeding in individuals taking direct oral anticoagulants (DOACs) submitted to dental extractions. METHODS: Intraoperative bleeding was evaluated by using total collected bleeding corrected by absorbance reading (dental bleeding score). To monitoring bleeding episodes from the day of surgery, this cohort was followed up until the seventh postoperative day. RESULTS: Forty-five procedures were performed in three comparative groups, patients under DOACs, individuals taking vitamin K antagonists (VKAs) and without anticoagulant therapy. No bleeding events were observed in procedures carried out in individuals of the DOAC group. Additional hemostatic measures were required in two procedures in the VKA group and one in the non-anticoagulated group. The dental bleeding scores obtained for the DOAC and VKA groups were similar. CONCLUSIONS: Our data suggest that the DOAC therapy did not result in increased bleeding outcomes in this sample.

Estrogen protects dental roots from orthodontic-induced inflammatory resorption.

OBJECTIVE: Root resorption is a side effect of orthodontic tooth movement (OTM). Despite the recognized role of estrogen on bone, there is little information about their effects on orthodontic-induced inflammatory root resorption (OIIRR). We aimed to investigate if estrogen deficiency affects OIIRR in two mice strains. METHODS: Female Balb/C (Balb) and C57BL6/J (C57) mice were ovariectomized (OVX) and replaced with estradiol (E2). Tooth samples subjected or not to OTM were collected and analyzed by microCT, histomorphometry and qPCR. RESULTS: OVX resulted in decreased root volume (RV/TV) and root mineral density (RMD) in Balb mice without OTM. In contrast, OVX did not modify physiological root structure of C57 mice. OTM and OIIRR were increased after OVX in both mice strains after 30 days. E2 replacement reversed this phenotype in Balb, but not in C57 mice. Due to the significant increase of OIIRR in OVX Balb mice, the expression of key molecules was investigated in periodontium. Accordingly, these mice showed increased expression of receptor activator of nuclear factor kappa-B ligand (RANKL), tumor necrosis factor alpha, matrix metalloproteinases-2 and -13 and decreased osteoprotegerin (OPG) and interleukin-10 expression after OTM. E2 replacement reversed the changes of these markers. CONCLUSION: The lack of estrogen in Balb mice without OTM triggered loss of root structure which was positively correlated to RANKL/OPG ratio. Regardless of mouse strain, the absence of estrogen following OTM induced OIIRR. Mechanisms involve the imbalance of RANKL/OPG system, inflammatory and osteoclastic makers.

Photobiomodulation Enhances Cisplatin Cytotoxicity in a Culture Model with Oral Cell Lineages.

Cisplatin plays a central role in cancer chemotherapy, but resistance to this drug remains a major obstacle in treatment. Drawbacks related to cisplatin failure may be associated with cell energy metabolism. This study investigated whether photobiomodulation (PBM) can potentiate the effects of cisplatin on keratinocytes (HaCat) and cancer cells (SCC25 and HN12). Cells were treated with laser (GaAlAs; 660 nm; 60 mW; 0.33 J; 2.14 W cm-2 ; 11.7 J cm-2 and 6 s) and cisplatin (7.8 µg mL-1 ) to evaluate cell viability, Ki-67, VEGF, TGF-ß1, EGF expression and ROS production. Observations were validated in the SCC25 cell lineage, where the type of cell death (necrosis/apoptosis) and the amount of ATP were assessed. Cell lineages showed increased sensitivity to cisplatin associated with PBM (Cis-PBM). Ki-67 was augmented in all cell lineages treated with Cis-PBM when compared to cisplatin alone (Cis). Cis or Cis-PBM significantly decreased VEGF expression in cancer cells, while no changes were seen in the expression of TGF-ß1 or EGF compared to control. ROS levels were similar in the Cis and Cis-PBM groups. Cells treated with Cis-PBM died by apoptosis, leading to greater consumption of ATP. These observations suggest that PBM may potentiate the effects of cisplatin, leading to increased drug cytotoxicity and enhanced cell death.

ST2 regulates bone loss in a site-dependent and estrogen-dependent manner.

Interleukin-33 (IL-33) and its receptor, ST2, are implicated in bone remodeling. The lack of estrogen after menopause results in an accelerated bone loss. Here we investigated the role of ST2 in the bone loss induced by estrogen deficiency. ST2-deficient mice (ST2-/- ) and their littermates (wildtype [WT]) were ovariectomized (OVX), while ovary-intact mice were used as controls. Bone sites were analyzed by microcomputed tomography, histomorphometry, and quantitative real-time polymerase chain reaction (qPCR). Deletion of IL-33 or ST2 resulted in a similar bone loss in the femur and maxilla. Ovariectomy in WT mice caused bone loss in the same areas. The lack of ST2 in OVX mice did not alter bone remodeling in the femur but prevented bone loss in the maxilla. Consistently, ovariectomy increased the IL-33 messenger RNA (mRNA) levels in the maxilla but not in the femur. Under mechanical stimulation, ovariectomy and ST2 deletion independently increased bone remodeling induced by orthodontic tooth movement, which was also associated with a greater number of osteoclasts and a reduced number of osteoblasts in the maxillary bone. ST2-/- OVX mice, however, displayed twice as many osteoblasts as that of WT OVX mice. Ovariectomy and ST2 deletion differently altered the cytokine mRNA levels in the maxilla. Remarkably, interleukin-10 expression was decreased in both WT OVX and ST2-/- mice, and this reduction was completely restored in ST2-/- OVX mice. The results demonstrate that estrogen and IL33/ST2 independently protect against bone loss. However, the ovariectomy-induced bone loss is IL-33/ST2-dependent in the maxilla but not in the femur, indicating a bimodal and site-specific role of ST2 in bone remodeling.

The chemokine fragment CXCL9(74-103) diminishes neutrophil recruitment and joint inflammation in antigen-induced arthritis.

This study investigates if treatment with a peptide corresponding to the 30 C-terminal amino acids of CXCL9, CXCL9(74-103), ameliorates joint inflammation in a murine model of antigen-induced arthritis (AIA). AIA was induced in male C57BL/6J mice. Intravenous injection of CXCL9(74-103), simultaneously performed with a tibiofemoral challenge with methylated BSA (mBSA) as antigen in mice immunized with mBSA, diminished the accumulation of leukocytes, in particular neutrophils, in the synovial cavity. The levels of the chemokines CXCL1, CXCL2, and CXCL6 and of the cytokine IL-6 were decreased in inflamed periarticular tissue of mice treated with the CXCL9-derived peptide compared to non-treated AIA mice. In addition, CXCL9(74-103) treatment substantially reduced joint and cartilage damage. CXCL9(74-103) competes with CXCL6 and CCL3 for binding to the glycosaminoglycans heparan sulfate and chondroitin sulfate in vitro. In vivo, CXCL9(74-103) quickly binds to blood vessels in joints as observed by confocal microscopy. Next, we evaluated if later treatment with CXCL9(74-103) had a beneficial impact on joint inflammation. CXCL9(74-103) injection 6 h after mBSA challenge still reduced neutrophil accumulation in the joint, although it did not reduce chemokine and IL-6 concentrations. However, a delay of treatment until 12 h after challenge had no effect on cell recruitment and chemokine and IL-6 levels. Taken together, we demonstrated that treatment with a peptide, which interferes with the interaction between chemokines and glycosaminoglycans, from the beginning of the disease controlled the massive accumulation of neutrophils in the joint of AIA mice, greatly impacting on joint inflammation and tissue damage.

Lactation induces increases in the RANK/RANKL/OPG system in maxillary bone.

The underlying causes of maxillary bone loss during lactation remain poorly understood. We evaluated the impact of lactation on physiological and mechanically-induced alveolar bone remodeling. Nulliparous non-lactating (N-LAC) and 21-day lactating (LAC) mice underwent mechanically-induced bone remodeling by orthodontic tooth movement (OTM). Micro-computed tomography (microCT) was performed in the maxilla, femur and vertebra. Tartrate-resistant-acid phosphatase (TRAP) and Masson's trichrome labelling was performed in the maxillary bone and gene expression was determined in the periodontal ligament. The effect of prolactin on osteoclast (OCL) and osteoblast (OBL) differentiation was also investigated in N-LAC and LAC mice. Lactation increased alveolar bone loss in the maxilla, femur and vertebra, while OTM was enhanced. The number of OCL and OBL was higher in the maxilla of LAC mice. OTM increased OCL in both groups; while OBL was increased only in N-LAC but not in LAC mice, in which cell numbers were already elevated. The alveolar bone loss during lactation was associated with increased expression of receptor activator of nuclear factor-KappaB (RANK), RANK ligand (RANKL), and osteoprotegerin (OPG) in the maxilla. OTM induced the same responses in N-LAC mice, whereas it had no further effect in LAC mice. Lactation enhanced differentiation of OCL and OBL from bone marrow cells, and prolactin recapitulated OCL differentiation in N-LAC mice. Thus, lactation increases physiological maxillary bone remodeling and OTM, and both require activation of RANK/RANKL/OPG system. These findings expand our knowledge of lactation-induced osteopenia and have possible impact on clinical practice regarding orthodontic treatments and dental implants in lactating women.

Oral surgery in patients under antithrombotic therapy: perioperative bleeding as a significant risk factor for postoperative hemorrhage.

: To investigate perioperative and postoperative bleeding, complications in patients under therapy with anticoagulant or antiplatelet drugs submitted to oral surgery. To evaluate the risk of bleeding and safety for dental surgery, a retrospective chart review was performed. Medical and dental records of patients taking oral antithrombotic drugs undergoing dental surgery between 2010 and 2015 were reviewed. Results were statistically analyzed using Fisher's exact test, t test or the χ test. One hundred and seventy-nine patients underwent 293 surgical procedures. A total of eight cases of perioperative and 12 episodes of postoperative bleeding were documented. The complications were generally managed with local measures and did not require hospitalization. We found significant association of postoperative hemorrhage with increased perioperative bleeding (P = 0.043) and combination of anticoagulant and antiplatelet therapy (P < 0.001). The chance of postoperative hemorrhage for procedures with increased perioperative bleeding is 8.8 times bigger than procedures without perioperative bleeding. Dental surgery in patients under antithrombotic therapy might be carried out without altering the regimen because of low risk of perioperative and postoperative bleeding. However, patients with increased perioperative bleeding should be closely followed up because of postoperative complications risk.

Dental management for patients undergoing heart valve surgery.

This study sought to review current guidelines and the most optimal dental management for patients undergoing cardiac valve surgery.

The role of 5-lipoxygenase in Aggregatibacter actinomycetemcomitans-induced alveolar bone loss.

AIM: Leukotrienes (LTs) are pro-inflammatory lipid mediators formed by the enzyme 5-lipoxygenase (5-LO). The involvement of 5-LO metabolites in periodontal disease (PD) is not well defined. This study aimed to assess the role of 5-LO in experimental PD induced by Aggregatibacter actinomycetemcomitans (Aa). MATERIAL AND METHODS: In vivo experiments were carried out using SV129 wild-type (WT) and 5-LO-deficient (5lo-/- ) mice inoculated with Aa. Osteoclasts were stimulated in vitro with AaLPS in the presence or not of selective inhibitors of the 5-LO pathway, or LTB4 or platelet-activating factor (PAF), as PAF has already been shown to increase osteoclast activity. RESULTS: In 5lo-/- mice, there were no loss of alveolar bone and less TRAP-positive osteoclasts in periodontal tissues, after Aa inoculation, despite local production of TNF-α and IL-6. The differentiation and activity of osteoclasts stimulated with AaLPS were diminished in the presence of BLT1 antagonist or 5-LO inhibitor, but not in the presence of cysteinyl leukotriene receptor antagonist. The osteoclast differentiation induced by PAF was impaired by the BLT1 antagonism. CONCLUSION: In conclusion, LTB4 but not CysLTs is important for Aa-induced alveolar bone loss. Overall, LTB4 affects osteoclast differentiation and activity and is a key intermediate of PAF-induced osteoclastogenesis.

Expression of Inflammatory Cytokines and Chemokines in Replanted Permanent Teeth with External Root Resorption.

INTRODUCTION: The progressive forms of inflammatory external root resorption (IERR) and replacement external root resorption (RERR) are serious complications and the main causes of tooth loss after replantation. This study aimed to investigate the expression pattern of inflammatory molecules in extracted human teeth presenting with external root resorption (ERR) after replantation. METHODS: Root fragments from 22 teeth showing IERR and 20 teeth with RERR were triturated using a homogenizer to extract inflammatory molecules. Interleukin-1ß (IL-1ß), IL-1Ra, transforming growth factor beta, IL-8/CXCL8, CCL2, CCL3, and CCL5 were measured using double-ligand enzyme-linked immunosorbent assay, and IL-2, IL-4, IL-6, IL-10, tumor necrosis factor alpha, interferon gamma, and IL-17A detection was performed using the multiplex Th1/Th2/Th17 Cytometric Bead Array kit (BD Biosciences, San Jose, CA). Cytokine and chemokine concentrations were compared in the RERR and IERR groups corrected by patients' age at the moment of extraction, survival time after replantation, and index of ERR, adopting a generalized estimation equation model. RESULTS: The IERR group showed higher levels of tumor necrosis factor alpha than the RERR group, even after correction for the index of ERR (P < .05). IL-1Ra levels were higher in the IERR group for moderate cases but higher in the RERR group for severe cases (P < .05). IL-4 concentration became higher with the increase of patients' age in the RERR group but did not vary in the IERR group (P < .05). CCL2 levels decreased with the increase of the patients' age at the moment of extraction irrespective of the type or index of ERR (P < .05). CONCLUSIONS: The present results showed differences in the immunologic profile of IERR and RERR that may be relevant to understanding the biological mechanisms underlying ERR.

Melanocortin agonism as a viable strategy to control alveolar bone loss induced by oral infection.

Alveolar bone loss is a result of an aggressive form of periodontal disease (PD) associated with Aggregatibacter actinomycetemcomitans (Aa) infection. PD is often observed with other systemic inflammatory conditions, including arthritis. Melanocortin peptides activate specific receptors to exert antiarthritic properties, avoiding excessing inflammation and modulating macrophage function. Recent work has indicated that melanocortin can control osteoclast development and function, but whether such protection takes place in infection-induced alveolar bone loss has not been investigated. The purpose of this study was to evaluate the role of melanocortin in Aa-induced PD. Mice were orally infected with Aa and treated with the melanocortin analog DTrp8-γMSH or vehicle daily for 30 d. Then, periodontal tissue was collected and analyzed. Aa-infected mice treated with DTrp8-γMSH presented decreased alveolar bone loss and a lower degree of neutrophil infiltration in the periodontium than vehicle-treated animals; these actions were associated with reduced periodontal levels of TNF-α, IFN-γ, and IL-17A. In vitro experiments with cells differentiated into osteoclasts showed that osteoclast formation and resorptive activity were attenuated after treatment with DTrp8-γMSH. Thus, melanocortin agonism could represent an innovative way to tame overexuberant inflammation and, at the same time, preserve bone physiology, as seen after Aa infection.-Madeira, M. F. M., Queiroz-Junior, C. M., Montero-Melendez, T., Werneck, S. M. C., Corrêa, J. D., Soriani, F. M., Garlet, G. P., Souza, D. G., Teixeira, M. M., Silva, T. A., Perretti, M. Melanocortin agonism as a viable strategy to control alveolar bone loss induced by oral infection.

Osteoprotective Effects of IL-33/ST2 Link to Osteoclast Apoptosis.

The relevance of IL-33 and its receptor ST2 for bone remodeling is not well-defined. Our aim was to assess the role and underlying mechanisms of IL-33/ST2 in mechanically induced bone remodeling. BALB/c (wild type) and ST2 deficient (St2(-/-)) mice were subjected to mechanical loading in alveolar bone. Microtomography, histology, and real-time quantitative PCR were performed to analyze bone parameters, apoptosis and bone cell counts, and expression of bone remodeling markers, respectively. MC3T3-E1 osteoblastic cells and bone marrow cells were used to verify if mechanical force triggered IL-33 and ST2 expression as well as the effects of IL-33 on osteoclast differentiation and activity. Mechanical loading increased the expression of IL-33 and ST2 in alveolar bone in vivo and in osteoblastic cells in vitro. St2(-/-) mice had increased mechanical loading-induced bone resorption, number of osteoclasts, and expression of proresorptive markers. In contrast, St2(-/-) mice exhibited reduced numbers of osteoblasts and apoptotic cells in periodontium and diminished expression of osteoblast signaling molecules. In vitro, IL-33 treatment inhibited osteoclast differentiation and activity even in the presence of receptor activator of NF-κB ligand. IL-33 also increased the expression of pro-apoptotic molecules, including Bcl-2-associated X protein (BAX), cell-surface Fas receptor (FAS), FASL, FAS-associated death domain, tumor necrosis factor-related apoptosis-inducing ligand, and BH3 interacting-domain death (BID). Overall, these findings suggest that IL-33/ST2 have anti-osteoclastogenic effects and reduce osteoclast formation and activity by inducing their apoptosis.