Bone Resorption Caused by Three Periodontal Pathogens In Vivo in Mice Is Mediated in Part by Prostaglandin

ABSTRACT Gingival inflammation, bacterial infection, alveolar bone destruction, and subsequent tooth loss are characteristic features of periodontal disease, but the precise mechanisms of bone loss are poorly understood. Most animal models of the disease require injury to gingival tissues or teeth, and the effects of microorganisms are thus complicated by host responses to tissue destruction. To determine whether three putative periodontal pathogens, Porphyromonas gingivalis, Campylobacter rectus, andFusobacterium nucleatum, could cause localized bone resorption in vivo in the absence of tissue injury, we injected live or heat-killed preparations of these microorganisms into the subcutaneous tissues overlying the calvaria of normal mice once daily for 6 days and then examined the bones histologically. We found that all three microorganisms (both live and heat killed) stimulated bone resorption and that the strain of F. nucleatum used appeared to be the strongest inducer of osteoclast activity. Treatment of the mice concomitantly with indomethacin reduced but did not completely inhibit bone resorption by these microorganisms, suggesting that their effects were mediated, in part, by arachidonic acid metabolites (e.g., prostaglandins). Our findings indicate that these potential pathogens can stimulate bone resorption locally when placed beside a bone surface in vivo in the absence of prior tissue injury and support a role for them in the pathogenesis of bone loss around teeth in periodontitis.

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Interleukin-6 Deficiency Increases Inflammatory Bone Destruction

Infection and Immunity ◽

10.1128/iai.69.2.744-750.2001 ◽

2001 ◽

Vol 69 (2) ◽

pp. 744-750 ◽

Cited By ~ 79

Author(s):

Khaled Balto ◽

Hajime Sasaki ◽

Philip Stashenko

Keyword(s):

Bone Resorption ◽

Interleukin 1 ◽

Bone Destruction ◽

Fusobacterium Nucleatum ◽

Wild Type ◽

Periapical Lesions ◽

Elevated Expression ◽

Pulp Exposure ◽

Anti Inflammatory

ABSTRACT Periapical bone destruction occurs as a consequence of pulpal infection. In previous studies, we showed that interleukin-1 (IL-1) is the primary stimulator of bone destruction in this model. IL-6 is a pleiotropic cytokine that is induced in these infections and has both pro- and anti-inflammatory activities. In the present study, we determined the role of IL-6 in regulating IL-1 expression and bone resorption. The first molars of IL-6 knockouts (IL-6−/−) and wild-type mice were subjected to surgical pulp exposure and infection with a mixture of four common pulpal pathogens, includingPrevotella intermedia, Fusobacterium nucleatum,Peptostreptococcus micros, and Streptococcus intermedius. Mice were killed after 21 days, and bone destruction and cytokine expression were determined. Surprisingly, bone destruction was significantly increased in IL-6−/− mice versus that in wild-type mice (by 30%; P < 0.001). In a second experiment, the effects of chronic (IL-6−/−) IL-6 deficiency and short-term IL-6 deficiency induced by in vivo antibody neutralization were determined. Both IL-6−/− (30%;P < 0.001) and anti-IL-6 antibody-treated mice (40%;P < 0.05) exhibited increased periapical bone resorption, compared to wild-type controls. The increased bone resorption in IL-6-deficient animals correlated with increases in osteoclast numbers, as well as with elevated expression of bone-resorptive cytokines IL-1α and IL-1β, in periapical lesions and with decreased expression of the anti-inflammatory cytokine IL-10. These data demonstrate that endogenous IL-6 expression has significant anti-inflammatory effects in modulating infection-stimulated bone destruction in vivo.

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IL-17A gene transfer induces bone loss and epidermal hyperplasia associated with psoriatic arthritis

Annals of the Rheumatic Diseases ◽

10.1136/annrheumdis-2013-204782 ◽

2014 ◽

Vol 74 (6) ◽

pp. 1284-1292 ◽

Cited By ~ 46

Author(s):

Iannis E Adamopoulos ◽

Erika Suzuki ◽

Cheng-Chi Chao ◽

Dan Gorman ◽

Sarvesh Adda ◽

...

Keyword(s):

Psoriatic Arthritis ◽

Gene Transfer ◽

Bone Resorption ◽

Bone Loss ◽

Bone Destruction ◽

Chronic Inflammatory Disease ◽

Epidermal Hyperplasia ◽

Osteoclast Precursors

BackgroundPsoriatic arthritis (PsA) is a chronic inflammatory disease characterised by clinical features that include bone loss and epidermal hyperplasia. Aberrant cytokine expression has been linked to joint and skin pathology; however, it is unclear which cytokines are critical for disease initiation. Interleukin 17A (IL-17A) participates in many pathological immune responses; however, its role in PsA has not been fully elucidated.ObjectiveTo determine the role of IL-17A in epidermal hyperplasia and bone destruction associated with psoriatic arthritis.DesignAn in vivo gene transfer approach was used to investigate the role of IL-17A in animal models of inflammatory (collagen-induced arthritis) and non-inflammatory (receptor activator of NF-κB ligand (RANKL)-gene transfer) bone loss.ResultsIL-17A gene transfer induced the expansion of IL-17RA+CD11b+Gr1low osteoclast precursors and a concomitant elevation of biomarkers indicative of bone resorption. This occurred at a time preceding noticeable joint inflammation, suggesting that IL-17A is critical for the induction of pathological bone resorption through direct activation of osteoclast precursors. Moreover, IL-17A induced a second myeloid population CD11b+Gr1high neutrophil-like cells, which was associated with cutaneous pathology including epidermal hyperplasia, parakeratosis and Munro's microabscesses formation.ConclusionsCollectively, these data support that IL-17A can play a key role in the pathogenesis of inflammation-associated arthritis and/or skin disease, as observed in PsA.

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Autoinducer-2 and QseC Control Biofilm Formation and In Vivo Virulence of Aggregatibacter actinomycetemcomitans

Infection and Immunity ◽

10.1128/iai.01376-09 ◽

2010 ◽

Vol 78 (7) ◽

pp. 2919-2926 ◽

Cited By ~ 54

Author(s):

Elizabeth A. Novak ◽

HanJuan Shao ◽

Carlo Amorin Daep ◽

Donald R. Demuth

Keyword(s):

Bone Resorption ◽

Bone Loss ◽

Biofilm Formation ◽

Alveolar Bone ◽

Wild Type ◽

Two Component System ◽

Component System ◽

Autoinducer 2 ◽

Two Component

ABSTRACT Biofilm formation by the periodontal pathogen Aggregatibacter actinomycetemcomitans is dependent upon autoinducer-2 (AI-2)-mediated quorum sensing. However, the components that link the detection of the AI-2 signal to downstream gene expression have not been determined. One potential regulator is the QseBC two-component system, which is part of the AI-2-dependent response pathway that controls biofilm formation in Escherichia coli. Here we show that the expression of QseBC in A. actinomycetemcomitans is induced by AI-2 and that induction requires the AI-2 receptors, LsrB and/or RbsB. Additionally, inactivation of qseC resulted in reduced biofilm growth. Since the ability to grow in biofilms is essential for A. actinomycetemcomitans virulence, strains that were deficient in QseC or the AI-2 receptors were examined in an in vivo mouse model of periodontitis. The ΔqseC mutant induced significantly less alveolar bone resorption than the wild-type strain (P < 0.02). Bone loss in animals infected with the ΔqseC strain was similar to that in sham-infected animals. The ΔlsrB, ΔrbsB, and ΔlsrB ΔrbsB strains also induced significantly less alveolar bone resorption than the wild type (P < 0.03, P < 0.02, and P < 0.01, respectively). However, bone loss induced by a ΔluxS strain was indistinguishable from that induced by the wild type, suggesting that AI-2 produced by indigenous microflora in the murine oral cavity may complement the ΔluxS mutation. Together, these results suggest that the QseBC two-component system is part of the AI-2 regulon and may link the detection of AI-2 to the regulation of downstream cellular processes that are involved in biofilm formation and virulence of A. actinomycetemcomitans.

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Inflammasomes in Alveolar Bone Loss

Frontiers in Immunology ◽

10.3389/fimmu.2021.691013 ◽

2021 ◽

Vol 12 ◽

Author(s):

Yang Li ◽

Junqi Ling ◽

Qianzhou Jiang

Keyword(s):

Bone Resorption ◽

Bone Loss ◽

Bone Remodeling ◽

Host Defense ◽

Alveolar Bone ◽

Bone Destruction ◽

Alveolar Bone Loss ◽

Fine Tuning ◽

Inflammasome Activation ◽

Dependent Manner

Bone remodeling is tightly controlled by osteoclast-mediated bone resorption and osteoblast-mediated bone formation. Fine tuning of the osteoclast–osteoblast balance results in strict synchronization of bone resorption and formation, which maintains structural integrity and bone tissue homeostasis; in contrast, dysregulated bone remodeling may cause pathological osteolysis, in which inflammation plays a vital role in promoting bone destruction. The alveolar bone presents high turnover rate, complex associations with the tooth and periodontium, and susceptibility to oral pathogenic insults and mechanical stress, which enhance its complexity in host defense and bone remodeling. Alveolar bone loss is also involved in systemic bone destruction and is affected by medication or systemic pathological factors. Therefore, it is essential to investigate the osteoimmunological mechanisms involved in the dysregulation of alveolar bone remodeling. The inflammasome is a supramolecular protein complex assembled in response to pattern recognition receptors and damage-associated molecular patterns, leading to the maturation and secretion of pro-inflammatory cytokines and activation of inflammatory responses. Pyroptosis downstream of inflammasome activation also facilitates the clearance of intracellular pathogens and irritants. However, inadequate or excessive activity of the inflammasome may allow for persistent infection and infection spreading or uncontrolled destruction of the alveolar bone, as commonly observed in periodontitis, periapical periodontitis, peri-implantitis, orthodontic tooth movement, medication-related osteonecrosis of the jaw, nonsterile or sterile osteomyelitis of the jaw, and osteoporosis. In this review, we present a framework for understanding the role and mechanism of canonical and noncanonical inflammasomes in the pathogenesis and development of etiologically diverse diseases associated with alveolar bone loss. Inappropriate inflammasome activation may drive alveolar osteolysis by regulating cellular players, including osteoclasts, osteoblasts, osteocytes, periodontal ligament cells, macrophages, monocytes, neutrophils, and adaptive immune cells, such as T helper 17 cells, causing increased osteoclast activity, decreased osteoblast activity, and enhanced periodontium inflammation by creating a pro-inflammatory milieu in a context- and cell type-dependent manner. We also discuss promising therapeutic strategies targeting inappropriate inflammasome activity in the treatment of alveolar bone loss. Novel strategies for inhibiting inflammasome signaling may facilitate the development of versatile drugs that carefully balance the beneficial contributions of inflammasomes to host defense.

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Gamma Interferon (IFN-γ) and IFN-γ-Inducing Cytokines Interleukin-12 (IL-12) and IL-18 Do Not Augment Infection-Stimulated Bone Resorption In Vivo

Clinical and Diagnostic Laboratory Immunology ◽

10.1128/cdli.11.1.106-110.2004 ◽

2004 ◽

Vol 11 (1) ◽

pp. 106-110 ◽

Cited By ~ 36

Author(s):

Hajime Sasaki ◽

Khaled Balto ◽

Nobuyuki Kawashima ◽

Jean Eastcott ◽

Katsuaki Hoshino ◽

...

Keyword(s):

Bone Resorption ◽

Alveolar Bone ◽

Interleukin 1 ◽

Bone Destruction ◽

Gamma Interferon ◽

Interleukin 12 ◽

Wild Type ◽

Necrosis Factor Alpha ◽

Ifn Γ

ABSTRACT Periapical granulomas are induced by bacterial infection of the dental pulp and result in destruction of the surrounding alveolar bone. In previous studies we have reported that the bone resorption in this model is primarily mediated by macrophage-expressed interleukin-1 (IL-1). The expression and activity of IL-1 is in turn modulated by a network of Th1 and Th2 regulatory cytokines. In the present study, the functional roles of the Th1 cytokine gamma interferon (IFN-γ) and IFN-γ-inducing cytokines IL-12 and IL-18 were determined in a murine model of periapical bone destruction. IL-12−/−, IL-18−/−, and IFN-γ−/− mice were subjected to surgical pulp exposure and infection with a mixture of four endodontic pathogens, and bone destruction was determined by microcomputed tomography on day 21. The results indicated that all IL-12−/−, IL-18−/−, and IFN-γ−/− mice had similar infection-stimulated bone resorption in vivo as wild-type control mice. Mice infused with recombinant IL-12 also had resorption similar to controls. IFN-γ−/− mice exhibited significant elevations in IL-6, IL-10, IL-12, and tumor necrosis factor alpha in lesions compared to wild-type mice, but these modulations had no net effect on IL-1α levels. Recombinant IL-12, IL-18, and IFN-γ individually failed to consistently modulate macrophage IL-1α production in vitro. We conclude that, at least individually, endogenous IL-12, IL-18, and IFN-γ do not have a significant effect on the pathogenesis of infection-stimulated bone resorption in vivo, suggesting possible functional redundancy in proinflammatory pathways.

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Structural Dissection andIn VivoEffectiveness of a Peptide Inhibitor ofPorphyromonas gingivalisAdherence toStreptococcus gordonii

Infection and Immunity ◽

10.1128/iai.00361-10 ◽

2010 ◽

Vol 79 (1) ◽

pp. 67-74 ◽

Cited By ~ 73

Author(s):

Carlo Amorin Daep ◽

Elizabeth A. Novak ◽

Richard J. Lamont ◽

Donald R. Demuth

Keyword(s):

Bone Resorption ◽

Bone Loss ◽

Alveolar Bone ◽

Alveolar Bone Loss ◽

Peptide Inhibitor ◽

Dental Biofilm ◽

Streptococcal Antigen ◽

Α Helix

ABSTRACTThe interaction of the minor fimbrial antigen (Mfa) with streptococcal antigen I/II (e.g., SspB) facilitates colonization of the dental biofilm byPorphyromonas gingivalis.We previously showed that a 27-mer peptide derived from SspB (designated BAR) resembles the nuclear receptor (NR) box protein-protein interacting domain and potently inhibits this interactionin vitro. Here, we show that the EXXP motif upstream of the NR core α-helix contributes to the Mfa-SspB interaction and that BAR reducesP. gingivaliscolonization and alveolar bone lossin vivoin a murine model of periodontitis. Substitution of Gln for Pro1171or Glu1168increased the α-helicity of BAR and reduced its inhibitory activityin vitroby 10-fold and 2-fold, respectively. To determine if BAR preventsP. gingivalisinfectionin vivo, mice were first infected withStreptococcus gordoniiand then challenged withP. gingivalisin the absence and presence of BAR. Animals that were infected with either 109CFU ofS. gordoniiDL-1 or 107CFU ofP. gingivalis33277 did not show a statistically significant increase in alveolar bone resorption over sham-infected controls. However, infection with 109CFU ofS. gordoniifollowed by 107CFU ofP. gingivalisinduced significantly greater bone loss (P< 0.01) than sham infection or infection of mice with either organism alone.S. gordonii-infected mice that were subsequently challenged with 107CFU ofP. gingivalisin the presence of BAR exhibited levels of bone resorption similar to those of sham-infected animals. Together, these results indicate that both EXXP and the NR box are important for the Mfa-SspB interaction and that BAR peptide represents a potential therapeutic that may limit colonization of the oral cavity byP. gingivalis.

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Tannerella forsythia-induced Alveolar Bone Loss in Mice Involves Leucine-rich-repeat BspA Protein

Journal of Dental Research ◽

10.1177/154405910508400512 ◽

2005 ◽

Vol 84 (5) ◽

pp. 462-467 ◽

Cited By ~ 61

Author(s):

A. Sharma ◽

S. Inagaki ◽

K. Honma ◽

C. Sfintescu ◽

P.J. Baker ◽

...

Keyword(s):

Bone Loss ◽

Alveolar Bone ◽

Alveolar Bone Loss ◽

Leucine Rich Repeat ◽

Periodontal Pathogens ◽

Tannerella Forsythia ◽

Pathogenic Potential ◽

Important Virulence Factor ◽

Mouse Model Of Infection

Tannerella forsythia (formerly Bacteroides forsythus) is one of the periodontal pathogens recently implicated in the development of periodontal disease. The cell-surface-associated, as well as the secreted, leucine-rich-repeat protein (BspA) of this bacterium have been suggested to play roles in bacterial adherence, and also in inflammation, by triggering release of pro-inflammatory cytokines from monocytes and chemokines from osteoblasts, leading to inflammation and bone resorption. In this study, we sought to determine the pathogenic potential of T. forsythia and the in vivo role of the BspA protein in pathogenesis in the mouse model of infection-induced alveolar bone loss. The results showed alveolar bone loss in mice infected with the T. forsythia wild-type strain, whereas the BspA mutant was impaired. In conclusion, evidence is presented in support of T. forsythia as an important organism involved in inducing alveolar bone loss, and the BspA protein is an important virulence factor of this bacterium.

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PF-3845, a Fatty Acid Amide Hydrolase Inhibitor, Directly Suppresses Osteoclastogenesis through ERK and NF-κB Pathways In Vitro and Alveolar Bone Loss In Vivo

International Journal of Molecular Sciences ◽

10.3390/ijms22041915 ◽

2021 ◽

Vol 22 (4) ◽

pp. 1915

Author(s):

Hye-Jung Ihn ◽

Yi-Seul Kim ◽

Soomin Lim ◽

Jong-Sup Bae ◽

Jae-Chang Jung ◽

...

Keyword(s):

Bone Loss ◽

Alveolar Bone ◽

Fatty Acid Amide Hydrolase ◽

Osteoclast Differentiation ◽

Acid Amide ◽

Bone Destruction ◽

Alveolar Bone Loss ◽

Nuclear Factor ◽

Amide Hydrolase

Alveolar bone loss, the major feature of periodontitis, results from the activation of osteoclasts, which can consequently cause teeth to become loose and fall out; the development of drugs capable of suppressing excessive osteoclast differentiation and function is beneficial for periodontal disease patients. Given the difficulties associated with drug discovery, drug repurposing is an efficient approach for identifying alternative uses of commercially available compounds. Here, we examined the effects of PF-3845, a selective fatty acid amide hydrolase (FAAH) inhibitor, on receptor activator of nuclear factor kappa B ligand (RANKL)-mediated osteoclastogenesis, its function, and the therapeutic potential for the treatment of alveolar bone destruction in experimental periodontitis. PF-3845 significantly suppressed osteoclast differentiation and decreased the induction of nuclear factor of activated T-cells cytoplasmic 1 (NFATc1) and the expression of osteoclast-specific markers. Actin ring formation and osteoclastic bone resorption were also reduced by PF-3845, and the anti-osteoclastogenic and anti-resorptive activities were mediated by the suppression of phosphorylation of rapidly accelerated fibrosarcoma (RAF), mitogen-activated protein kinase (MEK), extracellular signal-regulated kinase, (ERK) and nuclear factor κB (NF-κB) inhibitor (IκBα). Furthermore, the administration of PF-3845 decreased the number of osteoclasts and the amount of alveolar bone destruction caused by ligature placement in experimental periodontitis in vivo. The present study provides evidence that PF-3845 is able to suppress osteoclastogenesis and prevent alveolar bone loss, and may give new insights into its role as a treatment for osteoclast-related diseases.

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2-NPPA Mitigates Osteoclastogenesis via Reducing TRAF6-Mediated c-fos Expression

Frontiers in Pharmacology ◽

10.3389/fphar.2020.599081 ◽

2021 ◽

Vol 11 ◽

Author(s):

Zhihao Chen ◽

Mina Ding ◽

Eunjin Cho ◽

Jihyoun Seong ◽

Sunwoo Lee ◽

...

Keyword(s):

Bone Resorption ◽

Bone Loss ◽

Bone Destruction ◽

Inhibitory Effect ◽

Bone Diseases ◽

Point Of View ◽

A Cell ◽

Fos Expression

Excessive bone resorption leads to bone destruction in pathological bone diseases. Osteoporosis, which occurs when osteoclast-mediated bone resorption exceeds osteoblast-mediated bone synthesis, is regarded a global health challenge. Therefore, it is of great importance to identify agents that can regulate the activity of osteoclasts and prevent bone diseases mediated mainly by bone loss. We screened compounds for this purpose and found that 2-(2-chlorophenoxy)-N-[2-(4-propionyl-1piperazinyl) phenyl] acetamide (2-NPPA) exhibited a strong inhibitory effect on osteoclastogenesis. 2-NPPA suppressed the mRNA and protein expression of several osteoclast-specific markers and blocked the formation of mature osteoclasts, reducing the F-actin ring formation and bone resorption activity. In a cell signaling point of view, 2-NPPA exhibited a significant inhibitory effect on the phosphorylation of nuclear factor kappa-B (NF-κB) and c-fos expression in vitro and prevented ovariectomy-induced bone loss in vivo. These findings highlighted the potential of 2-NPPA as a drug for the treatment of bone loss-mediated disorders.

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Estrogen Decreases Cytoskeletal Organization by Forming an ERα/SHP2/c-Src Complex in Osteoclasts to Protect against Ovariectomy-Induced Bone Loss in Mice

Antioxidants ◽

10.3390/antiox10040619 ◽

2021 ◽

Vol 10 (4) ◽

pp. 619

Author(s):

Hyun-Jung Park ◽

Malihatosadat Gholam-Zadeh ◽

Sun-Young Yoon ◽

Jae-Hee Suh ◽

Hye-Seon Choi

Keyword(s):

Bone Resorption ◽

Bone Loss ◽

Ring Formation ◽

Tartrate Resistant Acid Phosphatase ◽

Actin Ring ◽

Collagen Crosslinks ◽

Trap Staining ◽

Src Activation

Loss of ovarian function is closely related to estrogen (E2) deficiency, which is responsible for increased osteoclast (OC) differentiation and activity. We aimed to investigate the action mechanism of E2 to decrease bone resorption in OCs to protect from ovariectomy (OVX)-induced bone loss in mice. In vivo, tartrate-resistant acid phosphatase (TRAP) staining in femur and serum carboxy-terminal collagen crosslinks-1 (CTX-1) were analyzed upon E2 injection after OVX in mice. In vitro, OCs were analyzed by TRAP staining, actin ring formation, carboxymethylation, determination of reactive oxygen species (ROS) level, and immunoprecipitation coupled with Western blot. In vivo and in vitro, E2 decreased OC size more dramatically than OC number and Methyl-piperidino-pyrazole hydrate dihydrochloride (MPPD), an estrogen receptor alpha (ERα) antagonist, augmented the OC size. ERα was found in plasma membranes and E2/ERα signaling affected receptor activator of nuclear factor κB ligand (RANKL)-induced actin ring formation by rapidly decreasing a proto-oncogene tyrosine-protein kinase, cellular sarcoma (c-Src) (Y416) phosphorylation in OCs. E2 exposure decreased physical interactions between NADPH oxidase 1 (NOX1) and the oxidized form of c-Src homology 2 (SH2)-containing protein tyrosine phosphatase 2 (SHP2), leading to higher levels of reduced SHP2. ERα formed a complex with the reduced form of SHP2 and c-Src to decrease c-Src activation upon E2 exposure, which blocked a signal for actin ring formation by decreased Vav guanine nucleotide exchange factor 3 (Vav3) (p–Y) and Ras-related C3 botulinum toxin substrate 1 (Rac1) (GTP) activation in OCs. E2/ERα signals consistently inhibited bone resorption in vitro. In conclusion, our study suggests that E2-binding to ERα forms a complex with SHP2/c-Src to attenuate c-Src activation that was induced upon RANKL stimulation in a non-genomic manner, resulting in an impaired actin ring formation and reducing bone resorption.

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