Human rheumatoid synovial fibroblasts promote osteoclastogenic activity by activating RANKL via TLR-2 and TLR-4 activation

Effect of diesel exhaust particles on RANK/RANKL expression in in vivo and in vitro models of middle ear inflammation

OBJECTIVE

Increasing evidence suggests a link between middle ear inflammation and the development of diesel exhaust particles (DEPs). Chronic middle ear inflammation can lead to bone damage and remodeling. This study aimed to explore the impact of DEPs on the expression of interleukin (IL)-6 and RANKL under conditions of middle ear inflammation.

METHODS

DEPs were collected by burning fuel in a diesel engine at the Gwangju Institute of Science and Technology. Human middle ear epithelial cells were cultured to 70-80% confluence in culture plates and then treated with DEPs at concentrations of 0, 5, 10, 20, 40, and 80 μg/mL for 24 h. Cell viability was assessed manually. B6.SJL mice, aged 9 weeks, were exposed to DEPs at a concentration of 200 μg/m3 for 1 h daily over a period of 28 days. The expression levels of IL-6, tumor necrosis factor α, RANKL, and RANK were evaluated using hematoxylin and eosin staining and western blot analysis of the harvested middle ear samples.

RESULTS

The viability of human middle ear epithelial cells was found to decrease in a dose-dependent manner after 24 h. The mRNA expression level of IL-6 exhibited the most significant increase at the 48-h mark. In contrast, the mRNA expression levels of RANKL and RANK showed a marked increase as early as 6 h post-exposure, with both genes subsequently displaying a time-dependent decrease. Histological analysis revealed that the middle ear mucosa was thicker in the group exposed to DEPs compared to the control group. Additionally, the protein expression levels of IL-6 and RANKL were elevated in the DEP-exposed group relative to the normal control group.

CONCLUSIONS

We confirmed the expression of osteoclast-related proteins in the mouse middle ear. These results imply that air pollutants might affect RANKL/RANK signaling, which is associated with bone remodeling.

MyD88 exacerbates inflammation-induced bone loss by modulating dynamic equilibrium between Th17/Treg cells and subgingival microbiota dysbiosis

BACKGROUND

This study aimed to investigate the contribution of myeloid differentiation primary-response gene 88 (MyD88) on the differentiation of T helper type 17 (Th17) and regulatory T (Treg) cells and the emerging subgingival microbiota dysbiosis in Porphyromonas gingivalis-induced experimental periodontitis.

METHODS

Alveolar bone loss, infiltrated inflammatory cells, immunostained cells for tartrate-resistant acid phosphatase (TRAP), the receptor activator of nuclear factor-kB ligand (RANKL), and osteoprotegerin (OPG) were quantified by microcomputerized tomography and histological staining between age- and sex-matched homozygous littermates (wild-type [WT, Myd88+/+] and Myd88-/- on C57BL/6 background). The frequencies of Th17 and Treg cells in cervical lymph nodes (CLNs) and spleen were determined by flow cytometry. Cytokine expression in gingival tissues, CLNs, and spleens were studied by quantitative polymerase chain reaction (qPCR). Analysis of the composition of the subgingival microbiome and functional annotation of prokaryotic taxa (FAPROTAX) analysis were performed.

RESULTS

P. gingivalis-infected Myd88-/- mice showed alleviated bone loss, TRAP+ osteoclasts, and RANKL/OPG ratio compared to WT mice. A significantly higher percentage of Foxp3+CD4+ T cells in infected Myd88-/- CLNs and a higher frequency of RORγt+CD4+ T cells in infected WT mice was noted. Increased IL-10 and IL-17a expressions in gingival tissue at D14-D28 then declined in WT mice, whereas an opposite pattern was observed in Myd88-/- mice. The Myd88-/- mice exhibited characteristic increases in gram-positive species and species having probiotic properties, while gram-negative, anaerobic species were noted in WT mice. FAPROTAX analysis revealed increased aerobic chemoheterotrophy in Myd88-/- mice, whereas anaerobic chemoheterotrophy was noted in WT mice after P. gingivalis infection.

CONCLUSIONS

MyD88 plays an important role in inflammation-induced bone loss by modulating the dynamic equilibrium between Th17/Treg cells and dysbiosis in P. gingivalis-induced experimental periodontitis.

Overview, Trends, and Collaboration on Immunization, Vaccination, and Immunomodulation Therapies for Periodontitis: A Scientometric Study

AIM

To identify patterns and trends in the field of immunization, vaccination, and immunomodulation therapies for periodontitis.

MATERIALS AND METHODS

Metadata were collected from the Scopus database on publications related to these topics from January 1986 to February 2024. Several types of papers were included in this study, a total of 22 publications. Data were extracted from relevant publications and loaded into SciVal for analysis that were used to identify trends and patterns in the data, including cross-country collaboration, thematic evolution, and keyword distribution.

RESULTS

Mohsen Amin of Tehran University of Medical Sciences in Iran and S. Aadil Ahamed and Annie Kitty George of Saveetha Institute of Medical and Technical Sciences in India were found to be notable contributors in this field. India leads in terms of academic paper production, followed by Iran and China. The journals Expert Review of Vaccines and International Immunopharmacology have published significant papers in this field.

CONCLUSIONS

According to Lotka's Law, most authors have written only one paper, reflecting the distribution of productivity in many academic and scientific fields. Collaborations were observed between Iran and Canada, Korea and New Zealand, and the United States and Belgium. This study provides useful insight into the predominant trends and patterns in the scientific literature in the field of immunization, vaccination, and immunomodulation therapies for periodontitis.

CLINICAL SIGNIFICANCE

The findings of this study may help to understand the dynamics of the production on immunization, vaccination, and immunomodulation therapies could reduce the inflammation and progression of periodontitis, thus improving the patient's oral and overall health. How to cite this article: Mauricio F, Mendoza R, Silva H, et al. Overview, Trends, and Collaboration on Immunization, Vaccination, and Immunomodulation Therapies for Periodontitis: A Scientometric Study. J Contemp Dent Pract 2024;25(2):128-133.

In vitro osteoclastogenesis in autoimmune diseases - Strengths and pitfalls of a tool for studying pathological bone resorption and other disease characteristics

Osteoclasts play a critical role in bone pathology frequently associated with autoimmune diseases. Studying the etiopathogenesis of these diseases and their clinical manifestations can involve in vitro osteoclastogenesis, an experimental technique that utilizes osteoclast precursors that are relatively easily accessible from peripheral blood or synovial fluid. However, the increasing number of methodical options to study osteoclastogenesis in vitro poses challenges in translating findings to clinical research and practice. This review compares and critically evaluates previous research work based on in vitro differentiation of human osteoclast precursors originating from patients, which aimed to explain autoimmune pathology in rheumatic and enteropathic diseases. The discussion focuses primarily on methodical differences between the studies, including the origin of osteoclast precursors, culture conditions, and methods for identifying osteoclasts and assessing their activity. Additionally, the review examines the clinical significance of the three most commonly used in vitro approaches: induced osteoclastogenesis, spontaneous osteoclastogenesis, and cell co-culture. By analyzing and integrating the gathered information, this review proposes general connections between different studies, even in cases where their results are seemingly contradictory. The derived conclusions and future directions aim to enhance our understanding of a potential and limitations of in vitro osteoclastogenesis and provide a foundation for discussing novel methods (such as osteoclastogenesis dynamic) and standardized approaches (such as spontaneous osteoclastogenesis) for future use in autoimmune disease research.

Network-Based In Silico Analysis of New Combinations of Modern Drug Targets with Methotrexate for Response-Based Treatment of Rheumatoid Arthritis

BACKGROUND

Methotrexate (MTX), sulfonamides, hydroxychloroquine, and leflunomide have consistently resulted in remission with relatively mild to moderate adverse effects in patients with rheumatoid arthritis (RA). Modern medications outperform traditional treatments in that they target the pathological processes that underlie the development of RA.

METHODS

Following PRISMA guidelines, the authors accomplished a systematic review of the clinical efficacy of RA drugs, including the biologics such as Tumor Necrosis Factor-alpha inhibitors (TNF-α i) like Etanercept, Infliximab, Golimumab, and Adalimumab, kinase inhibitors (JAK inhibitors including Baricitinib and Tofacitanib), SyK inhibitors like Fos-tamatinib, MAPK inhibitors such as Talmapimod, T-cell inhibitors (Abatacept), IL6 blockers (Tocilizumab), and B cells depleters (Rituximab). These drugs have been found to increase remission rates when combined with MTX. A bioinformatics-based network was designed applying STRING-MODEL and the DrugBank database for the aforementioned drugs and MTX and, finally, employed for this systematic review.

RESULTS

Current research demonstrates that non-TNF-α inhibitor biologicals are particularly helpful in treating patients who did not respond well to conventional medications and TNF-α inhibitors. Despite being effective, these innovative drugs have a higher chance of producing hazardous side effects. The in silico investigations suggested an uncovered molecular interaction in combining MTX with other biological drugs. The STRING-MODEL showed that DHFR, TYMS, and ATIC, as the receptors of MTX, interact with each other but are not connected to the major interacted receptors.

CONCLUSIONS

New game-changing drugs including Mavrilimumab, Iguratimod, Upadacitinib, Fenebrutinib, and nanoparticles may be crucial in controlling symptoms in poorly managed RA patients. Emerging therapeutic targets like Toll-like 4 receptors, NLRP3 inflammasome complexes, and mesenchymal stem cells can further transform RA therapy.

HMGB1 and Toll-like receptors: potential therapeutic targets in autoimmune diseases

HMGB1, a nucleoprotein, is expressed in almost all eukaryotic cells. During cell activation and cell death, HMGB1 can function as an alarm protein (alarmin) or damage-associated molecular pattern (DAMP) and mediate early inflammatory and immune response when it is translocated to the extracellular space. The binding of extracellular HMGB1 to Toll-like receptors (TLRs), such as TLR2 and TLR4 transforms HMGB1 into a pro-inflammatory cytokine, contributing to the occurrence and development of autoimmune diseases. TLRs, which are members of a family of pattern recognition receptors, can bind to endogenous DAMPs and activate the innate immune response. Additionally, TLRs are key signaling molecules mediating the immune response and play a critical role in the host defense against pathogens and the maintenance of immune balance. HMGB1 and TLRs are reported to be upregulated in several autoimmune diseases, such as rheumatoid arthritis, systemic lupus erythematosus, type 1 diabetes mellitus, and autoimmune thyroid disease. The expression levels of HMGB1 and some TLRs are upregulated in tissues of patients with autoimmune diseases and animal models of autoimmune diseases. The suppression of HMGB1 and TLRs inhibits the progression of inflammation in animal models. Thus, HMGB1 and TLRs are indispensable biomarkers and important therapeutic targets for autoimmune diseases. This review provides comprehensive strategies for treating or preventing autoimmune diseases discovered in recent years.

Global trends in research of fibroblasts associated with rheumatoid diseases in the 21st century: A bibliometric analysis

Background

Rheumatoid Diseases (RDs) are a group of systemic auto-immune diseases that are characterized by chronic synovitis, and fibroblast-like synoviocytes (FLSs) play an important role in the occurrence and progression of synovitis. Our study is the first to adopt bibliometric analysis to identify the global scientific production and visualize its current distribution in the 21st century, providing insights for future research through the analysis of themes and keywords.

Methods

We obtained scientific publications from the core collection of the Web of Science (WoS) database, and the bibliometric analysis and visualization were conducted by Biblioshiny software based on R-bibliometrix.

Results

From 2000 to 2022, a total of 3,391 publications were reviewed. China is the most prolific country (n = 2601), and the USA is the most cited country (cited 7225 times). The Center of Experimental Rheumatology at University Hospital Zürich supported the maximum number of articles (n = 40). Steffen Gay published 85 records with 6263 total citations, perhaps making him the most impactful researcher. Arthritis and Rheumatism, Annals of Rheumatic Diseases, and Rheumatology are the top three journals.

Conclusion

The current study revealed that rheumatoid disease (RD)-related fibroblast studies are growing. Based on the bibliometric analysis, we summarized three important topics: activation of different subsets of fibroblasts; regulation of fibroblast function; and in vitro validation of existing discoveries. They are all valuable directions, which provide reference and guidance for researchers and clinicians engaged in the research of RDs and fibroblasts.

Electroacupuncture Alleviates Pain Responses and Inflammation in Collagen-Induced Arthritis Rats via Suppressing the TLR2/4-MyD88-NF-κB Signaling Pathway

Results

EA intervention and OxPAPC injection could relieve mechanical allodynia and thermal hyperalgesia caused by CIA. Paw edema and pathological damage of synovium were significantly ameliorated after EA intervention and OxPAPC injection. Furthermore, EA intervention and OxPAPC injection markedly reduced the contents of serum TNF-α, IL-1β, and IL-6, as well as the protein expression levels of synovial TLR2, TLR4, MyD88, and NF-κB p-p65. In particular, the expression of TLR2 and TLR4 on synovial fibroblasts and macrophages in synovium was significantly reduced by EA intervention.

Conclusions

Repeated EA stimulation at ST36 and SP6 can effectively relieve joint pain and synovial inflammation caused by RA in CIA rats. The analgesic and anti-inflammatory effect of EA may be closely related to the inhibition of innate immune responses driven by the TLR2/4-MyD88-NF-κB signaling pathway in the synovium.

Galectin-3 interacts with PD-1 and counteracts the PD-1 pathway-driven regulation of T cell and osteoclast activity in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is an autoimmune disease characterized by joint inflammation and bone erosions. The glycosylated programmed death-1 (PD-1) receptor plays an important role in regulating immune responses and maintaining tolerance. In this study, we focus on two features observed in RA: impaired PD-1 signalling and Galectin-3 (Gal-3) upregulation. We hypothesize that Gal-3 binds PD-1 and PD-1 ligands, potentially contributing to impaired PD-1 signalling. PD-1 and Gal-3 levels in RA synovial fluid (SF) and plasma were evaluated by ELISA. PD-1 and Gal-3 interaction was examined by Surface Plasmon Resonance and ELISA. PD-1, PD-L1 and Gal-3 expression on mononuclear cells from SF and peripheral blood as well as fibroblast-like synoviocytes were examined by flow cytometry. Effects of Gal-3 and PD-L1 on osteoclast formation was evaluated by tartrate-resistant acid phosphatase assay. We show that Gal-3 binds PD-1 and PD-L1. Results demonstrated high expression of PD-1 and Gal-3 on mononuclear cells, especially from SF. Gal-3 inhibited PD-1 signalling when PD-L1 was present. Furthermore, a role of Gal-3 in osteoclast formation was observed in vitro, both directly but also through PD-1:PD-L1 inhibition. Effects of Gal-3 on the PD-1 signalling axis are proposed to be inhibitory, meaning high Gal-3 levels in the complex synovial microenvironment are not desirable in RA. Preventing Gal-3's inhibitory role on PD-1 signalling could, therefore, be a therapeutic target in RA by affecting inflammatory T cell responses and osteoclasts.

Engineered Platelet Microparticle-Membrane Camouflaged Nanoparticles for Targeting the Golgi Apparatus of Synovial Fibroblasts to Attenuate Rheumatoid Arthritis

Synovial fibroblasts in rheumatoid arthritis (RA) joints mediate synovial hyperplasia, progressive joint destruction, and the potential spread of disease between joints by producing multiple pathogenic proteins. Here, we deliver all-trans retinoic acid (ATRA) to selectively down-regulate these pathogenic factors, with a Golgi-targeting platelet microparticle-mimetic nanoplatform (termed Gol-PMMNP) which comprises a nanoparticle core and a platelet microparticle membrane coating labeled with a Golgi apparatus-targeting peptide. Gol-PMMNPs are shown to target synovial fibroblasts derived from RA patients via integrin α2β1-mediated endocytosis and accumulate in the Golgi apparatus by retrograde transport. ATRA-loaded Gol-PMMNPs (ATRA-Gol-PMMNPs) cause structural disruption of the Golgi apparatus, leading to an efficient reduction of pathogenic protein secretion in RA synovial fibroblasts. In rats with collagen-induced arthritis, Gol-PMMNPs display an arthritic joint-specific distribution, and ATRA-Gol-PMMNPs effectively reduce concentrations of pathogenic factors therein, including inflammatory cytokines, chemokines, and matrix-degrading enzymes within these joints. Additionally, ATRA-Gol-PMMNP treatment results in inflammatory remission and decreased bone erosion in both arthritic and proximal joints. Furthermore, ATRA-Gol-PMMNPs induce negligible toxicity to major organs. Taken together, ATRA-Gol-PMMNPs inhibit the progression of RA through reducing the production of multiple pathogenic mediators by synovial fibroblasts.

Endotyping of Cholesteatoma: Which Molecular Biomarkers? A Systematic Review

Background: So far, no medical treatment is available for cholesteatoma (C) and the only effective therapy is complete surgical removal, but recurrence is common even after surgical treatment. While C is classically divided into two clinical phenotypes, congenital and acquired, only a few studies have focused on its potential biomarkers. This study aims to revise the literature to identify which biomarkers can define the endotype of C. Methods: We conducted a systematic review in accordance with the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) process to identify published experimental articles about molecular biomarkers in C. Results: KGF and its receptor, MMP-9, KRT-1, KRT-10, and MIF might be considered biomarkers of recurrence, whereas Ki-67, TLR-4, RANKL, IL17, MMP-2, MMP-9, IL6, TNF-α, should be considered more specifically as biomarkers of bony erosion. Conclusions: These results are interesting especially from a prognostic point of view, nevertheless more studies are needed to search new biomarkers of C that could completely change not only the therapeutic standards of the disease, but also the clinical history of C itself in the era of precision medicine.

Emerging proteoglycans and proteoglycan-targeted therapies in rheumatoid arthritis

Rheumatoid arthritis (RA) is a common auto-immune disease-causing inflammation of the joints and damage of the cartilage and bone. The pathogenesis of RA is characterized in many patients by the presence of antibodies against citrullinated proteins. In the joints, proteoglycans are key structural elements of extracellular matrix in the articular cartilage and synovium and are secreted as lubricants in the synovial fluid. Alterations of proteoglycans contribute to mechanism of disease in RA. Proteoglycans such as aggrecan can be citrullinated and become potential targets of the rheumatoid auto-immune response. Proteoglycans are also up-regulated in RA joints and/or undergo alterations of their regulatory functions over cytokines and chemokines, which promotes inflammation and bone damage. Recent studies have aimed to not only clarify these mechanisms but also develop novel proteoglycan-modulating therapeutics. These include agents altering the function and signaling of proteoglycans as well as tolerizing agents based on citrullinated aggrecan. This mini-review summarizes the most recent findings regarding the dysregulation of proteoglycans that contributes to RA pathogenesis and the potential for proteoglycan-modulating agents to improve RA therapy.

The Expression of Inflammasomes NLRP1 and NLRP3, Toll-Like Receptors, and Vitamin D Receptor in Synovial Fibroblasts From Patients With Different Types of Knee Arthritis

Activated rheumatoid arthritis (RA) synovial fibroblasts (SFs) are among the most important cells promoting RA pathogenesis. They are considered active contributors to the initiation, progression, and perpetuation of the disease; therefore, early detection of RASF activation could advance contemporary diagnosis and adequate treatment of undifferentiated early inflammatory arthritis (EA). In this study, we investigated the expression of nucleotide-binding, oligomerization domain (NOD)-like receptor family, pyrin domain containing (NLRP)1, NLRP3 inflammasomes, Toll-like receptor (TLR)1, TLR2, TLR4, vitamin D receptor (VDR), and secretion of matrix metalloproteinases (MMPs) in SFs isolated from patients with RA, osteoarthritis (OA), EA, and control individuals (CN) after knee surgical intervention. C-reactive protein, general blood test, anticyclic citrullinated peptide (anti-CCP), rheumatoid factor (RF), and vitamin D (vitD) in patients’ sera were performed. Cells were stimulated or not with 100 ng/ml tumor necrosis factor alpha (TNF-α) or/and 1 nM or/and 0.01 nM vitamin D3 for 72 h. The expression levels of NLRP1, NLRP3, TLR1, TLR2, TLR4, and VDR in all examined SFs were analyzed by quantitative real-time PCR (RT-qPCR). Additionally, the secretion of IL-1β by SFs and MMPs were determined by ELISA and Luminex technology. The expression of NLRP3 was correlated with the levels of CRP, RF, and anti-CCP, suggesting its implication in SF inflammatory activation. In the TNF-α-stimulated SFs, a significantly lower expression of NLRP3 and TLR4 was observed in the RA group, compared with the other tested forms of arthritis. Moreover, upregulation of NLRP3 expression by TNF-α alone or in combination with vitD3 was observed, further indicating involvement of NLRP3 in the inflammatory responses of SFs. Secretion of IL-1β was not detected in any sample, while TNF-α upregulated the levels of secreted MMP-1, MMP-7, MMP-8, MMP-12, and MMP-13 in all patient groups. Attenuating effects of vitD on the expression of NLRP3, TLR1, and TLR4 suggest potential protective effects of vitD on the inflammatory responses in SFs. However, longer studies may be needed to confirm or fully rule out the potential implication of vitD in SF activation in inflammatory arthritis. Both VDR and NLRP3 in the TNF-α-stimulated SFs negatively correlated with the age of patients, suggesting potential age-related changes in the local inflammatory responses.

Group 2 innate lymphoid cells in bone marrow regulate osteoclastogenesis in a reciprocal manner via RANKL, GM-CSF and IL-13

Group 2 innate lymphoid cells (ILC2s) are tissue-resident cells that play different roles in different organs by sensing surrounding environmental factors. Initially, it was thought that ILC2s in bone marrow (BM) are progenitors for systemic ILC2s, which migrate to other organs and acquire effector functions. However, accumulating evidence that ILC2s differentiate in peripheral tissues suggests that BM ILC2s may play a specific role in the BM as a unique effector per se. Here, we demonstrate that BM ILC2s highly express the receptor activator of nuclear factor κB ligand (RANKL), a robust cytokine for osteoclast differentiation and activation, and RANKL expression on ILC2s is up-regulated by interleukin (IL)-2, IL-7 and all-trans retinoic acid (ATRA). BM ILC2s co-cultured with BM-derived monocyte/macrophage lineage cells (BMMs) in the presence of IL-7 induce the differentiation of tartrate-resistant acid phosphatase (TRAP)-positive osteoclasts in a RANKL-dependent manner. In contrast, BM ILC2s stimulated with IL-33 down-regulate RANKL expression and convert BMMs differentiation into M2 macrophage-like cells rather than osteoclasts by granulocyte macrophage colony-stimulating factor (GM-CSF) and IL-13 production. Intravital imaging using two-photon microscopy revealed that a depletion of ILC2s prominently impaired in vivo osteoclast activity in an IL-7 plus ATRA-induced bone loss mouse model. These results suggest that ILC2s regulate osteoclast activation and contribute to bone homeostasis in both steady state and IL-33-induced inflammation.

Association of TLR 9 gene polymorphisms with remission in patients with rheumatoid arthritis receiving TNF-α inhibitors and development of machine learning models

Toll-like receptor (TLR)-4 and TLR9 are known to play important roles in the immune system, and several studies have shown their association with the development of rheumatoid arthritis (RA) and regulation of tumor necrosis factor alpha (TNF-α). However, studies that investigate the association between TLR4 or TLR9 gene polymorphisms and remission of the disease in RA patients taking TNF-α inhibitors have yet to be conducted. In this context, this study was designed to investigate the effects of polymorphisms in TLR4 and TLR9 on response to TNF-α inhibitors and to train various models using machine learning approaches to predict remission. A total of six single nucleotide polymorphisms (SNPs) were investigated. Logistic regression analysis was used to investigate the association between genetic polymorphisms and response to treatment. Various machine learning methods were utilized for prediction of remission. After adjusting for covariates, the rate of remission of T-allele carriers of TLR9 rs352139 was about 5 times that of the CC-genotype carriers (95% confidence interval (CI) 1.325-19.231, p = 0.018). Among machine learning algorithms, multivariate logistic regression and elastic net showed the best prediction with the area under the receiver-operating curve (AUROC) value of 0.71 (95% CI 0.597-0.823 for both models). This study showed an association between a TLR9 polymorphism (rs352139) and treatment response in RA patients receiving TNF-α inhibitors. Moreover, this study utilized various machine learning methods for prediction, among which the elastic net provided the best model for remission prediction.

CpG immunostimulatory oligodeoxynucleotide 1826 as a novel nasal ODN adjuvant enhanced the protective efficacy of the periodontitis gene vaccine in a periodontitis model in SD rats

BACKGROUND

We previously demonstrated that nasal administration of periodontitis gene vaccine (pVAX1-HA2-fimA) or pVAX1-HA2-fimA plus IL-15 as adjuvant provoked protective immunity in the periodontal tissue of SD rats. This study evaluated the immune effect of pVAX1-HA2-fimA plus CpG-ODN 1826 as an adjuvant in the SD rat periodontitis models to improve the efficacy of the previously used vaccine.

METHODS

Periodontitis was induced in maxillary second molars in SD rats receiving a ligature and infected with Porphyromonas gingivalis. Forty-two SD rats were randomly assigned to six groups: A, control without P. gingivalis; B, P. gingivalis with saline; C, P. gingivalis with pVAX1; D, P. gingivalis with pVAX1-HA2-fimA; E, P. gingivalis with pVAX1-HA2-fimA/IL-15; F, P. gingivalis with pVAX1-HA2-fimA+CpG ODN 1826 (30 µg). The levels of FimA-specific and HA2-specific secretory IgA antibodies in the saliva of rats were measured by ELISA. The levels of COX-2 and RANKL were detected by immunohistochemical assay. Morphometric analysis was used to evaluate alveolar bone loss. Major organs were observed by HE staining.

RESULTS

30 μg could be the optimal immunization dose for CpG-ODN 1826 and the levels of SIgA antibody were consistently higher in the pVAX1-HA2-fimA+CpG-ODN 1826 (30 µg) group than in the other groups during weeks 1-8 (P < 0.05, except week 1 or 2). Morphometric analysis demonstrated that pVAX1-HA2-fimA+CpG-ODN 1826 (30 µg) significantly reduced alveolar bone loss in ligated maxillary molars in group F compared with groups B-E (P < 0.05). Immunohistochemical assays revealed that the levels of COX-2 and RANKL were significantly lower in group F compared with groups B-E (P < 0.05). HE staining results of the major organs indicated that pVAX1-HA2-fimA with or without CpG-ODN 1826 was not toxic for in vivo use.

CONCLUSIONS

These results indicated that CpG-ODN 1826 (30 µg) could be used as an effective and safe mucosal adjuvant for pVAX1-HA2-fimA in SD rats since it could elicit mucosal SIgA responses and modulate COX-2 and RANKL production during weeks 1-8, thereby inhibiting inflammation and decreasing bone loss.

TLRs Play Crucial Roles in Regulating RA Synoviocyte

Rheumatoid arthritis (RA) is an autoimmune inflammatory disease comparing the inflammation of synovium. Macrophage-like synoviocytes and fibroblast-like synoviocytes (synoviocytes) are crucial ingredients of synovium. Therein, a lot of research has focused on synoviocytes. Researches demonstrated that TLR1, TLR2, TLR3, TLR4, TLR5, TLR6 TLR7 and TLR9 are expressed in synoviocyte. Additionally, the expression of TLR2, TLR3, TLR4 and TLR5 is increased in RA synoviocyte. In this paper, we review the exact role of TLR2, TLR3, TLR4 and TLR5 participate in regulating the production of inflammatory factors in RA synoviocyte. Furthermore, we discuss the role of vasoactive intestinal peptide (VIP), MicroRNA, Monome of Chinese herb and other cells (Monocyte and T cell) influence the function of synoviocyte by regulating TLRs. The activation of toll-like receptors (TLRs) in synoviocyte leads to the aggravation of arthritis, comparing with angiogenesis and bone destruction. Above all, TLRs are promising targets for managing RA.

Contribution of Toll-Like Receptors and the NLRP3 Inflammasome in Rheumatoid Arthritis Pathophysiology

Rheumatoid arthritis (RA) is a progressive autoimmune disease that is characterized by inflammation of the synovial joints leading to cartilage and bone damage. The pathogenesis is sustained by the production of pro-inflammatory cytokines including tumor necrosis factor (TNF), interleukin (IL)-1 and IL-6, which can be targeted therapeutically to alleviate disease severity. Several innate immune receptors are suggested to contribute to the chronic inflammation in RA, through the production of pro-inflammatory factors in response to endogenous danger signals. Much research has focused on toll-like receptors and more recently the nucleotide-binding domain and leucine-rich repeat pyrin containing protein-3 (NLRP3) inflammasome, which is required for the processing and release of IL-1β. This review summarizes the current understanding of the potential involvement of these receptors in the initiation and maintenance of inflammation and tissue damage in RA and experimental arthritis models.

Bioactive fractions and compound of Ardisia crispa roots exhibit anti-arthritic properties mediated via angiogenesis inhibition in vitro

Background

Ardisia crispa (Thunb.) A.DC (Primulaceae), is a medicinal herb traditionally used by Asian people as remedies to cure inflammatory related diseases, including rheumatism. The plant roots possess various pharmacological activities including antipyretic, anti-inflammation and antitumor. Previous phytochemical studies of the plant roots have identified long chain alkyl-1,4-benzoquinones as major constituents, together with other phytochemicals. Hexane fraction of the plant roots (ACRH), was previously reported with anti-angiogenic and anti-arthritic properties, while its effect on their anti-arthritic in vitro, is yet unrevealed. Considering the significance of angiogenesis inhibition in developing new anti-arthritic agent, thus we investigated the anti-arthritic potential of Ardisia crispa roots by suppressing angiogenesis, in vitro.

Methods

Ardisia crispa roots hexane extract (ACRH) was prepared from the plant roots using absolute n-hexane. ACRH was fractionated into quinone-rich fraction (QRF) and further isolated to yield benzoquinonoid compound (BQ), respectively. In vitro experiments using VEGF-induced human umbilical vein endothelial cells (HUVECs) and IL-1β-induced human fibroblast-like synoviocytes for rheumatoid arthritis (HFLS-RA) were performed to evaluate the effects of these samples on VEGF-induced HUVECs proliferation and tube formation, and towards IL-1β-induced HFLS-RA proliferation, invasion, and apoptosis, respectively. Therapeutic concentrations (0.05, 0.5, and 5 μg/mL) tested in this study were predetermined based on the IC₅₀ values obtained from the MTT assay.

Results

ACRH, QRF, and BQ exerted concentration-independent antiproliferative effects on VEGF-induced HUVECs and IL-1β-induced HFLS-RA, with IC₅₀ values at 1.09 ± 0.18, 3.85 ± 0.26, and 1.34 ± 0.16 μg/mL in HUVECs; and 3.60 ± 1.38, 4.47 ± 0.34, and 1.09 ± 0.09 μg/mL in HFLS-RA, respectively. Anti-angiogenic properties of these samples were verified via significant inhibition on VEGF-induced HUVECs tube formation, in a concentration-independent manner. The invasiveness of IL-1β-induced HFLS-RA was also significantly inhibited in a concentration-independent manner by all samples. ACRH and BQ, but not QRF, significantly enhanced the apoptosis of IL-1β-induced HFLS-RA elicited at their highest concentration (5 μg/mL) (P < 0.05).

Conclusions

These findings highlight the bioactive fractions and compound from Ardisia crispa roots as potential anti-arthritic agents by inhibiting both HUVECs and HFLS-RA’s cellular functions in vitro, possibly mediated via their anti-angiogenic effects.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12906-021-03341-y.

Stability of housekeeping genes in inflamed joints of spontaneous and collagen-induced arthritis in DBA/1 mice

BACKGROUND

DBA/1 mice arthritis models have contributed to our understanding of human rheumatoid arthritis (RA) and spondyloarthritis (SpA) pathogenesis, as well as the exploration of therapeutic targets for treatment. Quantitative polymerase chain reaction (qPCR) is an indispensable tool in molecular research, which requires reference gene validation to obtain consistent and reliable results.

OBJECTIVE

To determine the stability of candidate reference genes for qPCR in the joint of collagen-induced arthritis (CIA) and spontaneous arthritis (SpAD) DBA/1 mice.

METHODS

The expression of eleven commonly used reference genes (ACTB, B2M, EF1a, GAPDH, HMBS, HPRT, PPIB, RPL13A, SDHA, TBP, and YWHAZ) was assessed by qPCR and the data were compared using delta-Ct methods and the geNorm, NormFinder, and RefFinder software packages. Genes identified as stable in each model were used for the quantification of inflammatory cytokines RESULTS: The gene stabilities differed between the two arthritis models in the DBA/1 mice. EF1a and RPL13A were the best reference genes for SpAD, while RPL13A and TBP were the best for the CIA. These genes allowed the data normalization for the quantification of the inflammatory cytokines in both models; these results showed an increase in the expression of IL-1B, IL-12B, IL-17A, and IL-6 in the inflamed joints. The use of different primer sequences for the same reference gene resulted in different relative quantification values.

CONCLUSION

This study demonstrates that commonly used reference genes may not be suitable for arthritic tissues from DBA/1 mice, and strengthening the principle that meticulous validation of reference genes is essential before each experiment to obtain valid and reproducible qPCR data for analysis or interpretation.

Probiotic Composition and Chondroitin Sulfate Regulate TLR-2/4-Mediated NF-κB Inflammatory Pathway and Cartilage Metabolism in Experimental Osteoarthritis

The therapeutic potential of using probiotics to treat osteoarthritis (OA) has only recently been recognized, with a small number of animal and human studies having been undertaken. The aim of this study was to describe the effect of a probiotic composition (PB) and chondroitin sulfate (CS), administered separately or in combination, on Tlr2, Tlr4, Nfkb1, and Comp gene expression in cartilage and levels of cytokines (IL-6, IL-8, TGF-β1, IGF-1) and COMP, ACAN, CHI3L1, CTSK, and TLR-2 in serum during monoiodoacetate (MIA)-induced OA in rats. Expression of Tlr2, Tlr4, Nfkb1, and Comp in cartilage was analyzed using one-step SYBR Green real-time RT-PCR. The levels of IL-6, IL-8, TGF-β1, IGF-1, COMP, ACAN, CHI3L1, CTSK, and TLR-2 were measured in serum by enzyme-linked immunosorbent assay. Experimental OA caused an upregulation in Tlr2, Tlr4, Nfkb1, and downregulation of Comp expression in the cartilage. MIA-OA caused a significant increase of TLR-2 soluble form and IL-6, IL-8, TGF-β1, COMP, ACAN, CHI3L1, and CTSK levels in the blood serum; the level of IGF-1, on contrary, decreased. Separate administration of PB and CS raised expression of Comp and reduced Tlr2, Tlr4, and Nfkb1 expressions in cartilage. The levels of the studied markers of cartilage metabolism in serum were decreased or increased (IGF-1). The combined use of PB and CS was more effective than separate application approaching above-mentioned parameters to control. The outcomes of our research prove that multistrain live probiotic composition amplifies the positive action of CS in osteoarthritis attenuation and necessitates further investigation with large-scale randomized controlled trial.

The Effect of Inflammation on Bone

Bone remodeling is the continual process to renew the adult skeleton through the sequential action of osteoblasts and osteoclasts. Nuclear factor RANK, an osteoclast receptor, and its ligand RANKL, expressed on the surface of osteoblasts, result in coordinated control of bone remodeling. Inflammation, a feature of illness and injury, plays a distinct role in skewing this process toward resorption. It does so via the interaction of inflammatory mediators and their related peptides with osteoblasts and osteoclasts, as well as other immune cells, to alter the expression of RANK and RANKL. Such chemical mediators include TNFα, glucocorticoids, histamine, bradykinin, PGE2, systemic RANKL from immune cells, and interleukins 1 and 6. Conditions, such as periodontal disease and alveolar bone erosion, aseptic prosthetic loosening, rheumatoid arthritis, and some sports related injuries are characterized by the result of this process. A thorough understanding of bone response to injury and disease, and ability to detect such biomarkers, as well as imaging to identify early structural and mechanical property changes in bone architecture, is important in improving management and outcomes of bone related pathology. While gut health and vitamin and mineral availability appear vitally important, nutraceuticals also have an impact on bone health. To date most pharmaceutical intervention targets inflammatory cytokines, although strategies to favorably alter inflammation induced bone pathology are currently limited. Further research is required in this field to advance early detection and treatments.

High-mobility group box 1 released by traumatic occlusion accelerates bone resorption in the root furcation area in mice

BACKGROUND AND OBJECTIVE

Traumatic occlusion can cause bone resorption without bacterial infection. Although bone resorption in periodontitis has been relatively well studied, little is known about bone resorption by traumatic occlusion. High-mobility group box 1 (HMGB1) is released from damaged tissue and has been recently shown to promote bone resorption in a murine periodontitis model and may also promote bone resorption by traumatic occlusion. The present study aimed to examine whether HMGB1 accelerates bone resorption by traumatic occlusion in mice.

MATERIALS AND METHODS

Occlusal trauma was induced in the lower left first molar of mice by bonding a wire to the upper left first molar, and bone resorption and osteoclast formation were evaluated histochemically. The expression of HMGB1, Toll-like receptor 4 (TLR4; the receptor for HMGB1), and receptor activator of NFκB ligand (RANKL; an essential osteoclast differentiation factor) was evaluated immunohistologically. In addition, mice were administrated with an anti-HMGB1-neutralizing antibody to analyze the role of HMGB1.

RESULTS

Bone resorption and osteoclast formation gradually increased until day 5 at the furcation area after the application of traumatic occlusion. Expression of HMGB1 was observed at the furcation area on day 1, but was attenuated by day 3. Expression of RANKL gradually increased until day 3, but was attenuated by day 5. Administration of anti-HMGB1 antibody significantly reduced the number of osteoclasts and the expression of RANKL and TLR4 at the furcation area.

CONCLUSION

Release of HMGB1 in the root furcation area accelerated bone resorption by up-regulating RANKL and TLR4 expression in mice with traumatic occlusion.

MiR-130a/Ndrg2 Axis Inhibits the Proliferation of Fibroblast-Like Synoviocytes in Rheumatoid Arthritis

Studies have found that N-myc downstream-regulated gene 2 (Ndrg2) is involved in the progression of rheumatoid arthritis (RA); however, the specific mechanism still remains unclear. Gene expression profiles in the tibial joints of the collagen-induced rheumatoid arthritis model were obtained using Gene Expression Omnibus database. Western blot and real-time PCR were respectively performed to determine the expression of Ndrg2 and gene messenger RNA. Cell viability was measured by Cell Counting Kit-8 (CCK-8) method, and cell cycle was detected by flow cytometry. Cell scratch assays were carried out to detect migration. The binding ability of miR-130a to Ndrg2-3'-UTR was predicted by TargetScan website and confirmed by dual luciferase assay. A collagen-induced arthritis rat model was constructed to observe the effects of miR-130a on arthritis index, hind limb swelling, volume of rat hind paw, and inflammation. Ndrg2 was found downregulated in RA tissues, and knockdown of Ndrg2 promoted fibroblast-like synoviocytes (FLS) proliferation and inflammation, while overexpressed Ndrg2 produced opposite results. Ndrg2 was predicted as a target gene for miR-130a, and miR-130a mimic promoted FLS proliferation, while miR-130a inhibitor suppressed FLS proliferation. Moreover, we found that miR-130a antagomir could significantly reduce the arthritis index, swelling degree, foot volume, and inflammatory factor levels; inhibit the expression of miR-130a; and promote the expression of Ndrg2. The miR-130a/Ndrg2 axis signaling pathway is involved in the progression of RA. Our findings provide a theoretical basis for the clinical treatment of RA.

Nanomedicines for the delivery of glucocorticoids and nucleic acids as potential alternatives in the treatment of rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease that affects 0.5-1% of the world population. Current treatments include on one hand non-steroidal anti-inflammatory drugs and glucocorticoids (GCs) for treating pain and on the other hand disease-modifying anti-rheumatic drugs such as methotrexate, Janus kinase inhibitors or biologics such as antibodies targeting mainly cytokine expression. More recently, nucleic acids such as siRNA, miRNA, or anti-miRNA have shown strong potentialities for the treatment of RA. This review discusses the way nanomedicines can target GCs and nucleic acids to inflammatory sites, increase drug penetration within inflammatory cells, achieve better subcellular distribution and finally protect drugs against degradation. For GCs such a targeting effect would allow the treatment to be more effective at lower doses and to reduce the administration frequency as well as to induce much fewer side-effects. In the case of nucleic acids, particularly siRNA, knocking down proteins involved in RA, could importantly be facilitated using nanomedicines. Finally, the combination of both siRNA and GCs in the same carrier allowed for the same cell to target both the GCs receptor as well as any other signaling pathway involved in RA. Nanomedicines appear to be very promising for the delivery of conventional and novel drugs in RA therapeutics. This article is categorized under: Therapeutic Approaches and Drug Discovery > Emerging Technologies Biology-Inspired Nanomaterials > Nucleic Acid-Based Structures.

Combined effects of probiotic and chondroprotector during osteoarthritis in rats

BACKGROUND

Osteoarthritis (OA) is a joint affection, defined by articular cartilage demolition, risks of which rise with age. The aim of this study was to compare the efficacy of chondroitin sulfate (CS) course and multistrain live probiotic (LP) administered alone or in combination on the expression of TLR-2, TLR-4, TNF-α and NF-κB in articular cartilage, subchondral bone and synovial membrane during OA in rats.

METHODS

OA was induced in male rats by injecting monoiodoacetate (MIA) in right hind knee. Therapeutic groups received 3 mg/kg of chondroprotector (ChP) CS for 28 days and/or 140 mg/kg of LP diet for 14 days. The expression of TLR-2, TLR-4, TNF-α and NF-κB in articular cartilage, subchondral bone and synovial membrane were determined with immunohistochemical staining kits (Thermo Fisher Scientific).

RESULTS

It was established that MIA injection is associated with long-term structural changes in joint tissues that corresponded to OA-like features and associated with activation of pathogen-recognizing molecules and proinflammatory signaling pathways expression. Separate therapy with ChP and probiotics slightly decreased OA score limiting cell death and subchondral bone resorption. However, these changes were not associated with a significant decrease in TLR-2, TLR-4, NF-kB and TNF-α expression. On the other hand, the combination of ChP and LP treatment significantly decreased OA score. This correlated with a decrease in TLR-2, TLR-4, NF-kB and TNF-α expression in chondrocytes and synovial cells.

CONCLUSIONS

The outcomes of our research prove that ChPs amplify the positive action of LPs in OA attenuation.

Platelets: emerging facilitators of cellular crosstalk in rheumatoid arthritis

Rheumatoid arthritis (RA) is an autoimmune disease in which a variety of circulating pro-inflammatory cells and dysregulated molecules are involved in disease aetiology and progression. Platelets are an important cellular element in the circulation that can bind several dysregulated molecules (such as collagen, thrombin and fibrinogen) that are present both in the synovium and the circulation of patients with RA. Platelets not only respond to dysregulated molecules in their environment but also transport and express their own inflammatory mediators, and serve as regulators at the boundary between haemostasis and immunity. Activated platelets also produce microparticles, which further convey signalling molecules and receptors to the synovium and circulation, thereby positioning these platelet-derived particles as strategic regulators of inflammation. These diverse functions come together to make platelets facilitators of cellular crosstalk in RA. Thus, the receptor functions, ligand binding potential and dysregulated signalling pathways in platelets are becoming increasingly important for treatment in RA. This Review aims to highlight the role of platelets in RA and the need to closely examine platelets as health indicators when designing effective pharmaceutical targets in this disease.

SEM BSE 3D Image Analysis of Human Incus Bone Affected by Cholesteatoma Ascribes to Osteoclasts the Bone Erosion and VpSEM dEDX Analysis Reveals New Bone Formation

Bone erosion is considered a typical characteristic of advanced or complicated cholesteatoma (CHO), although it is still a matter of debate if bone erosion is due to osteoclast action, being the specific literature controversial. The purpose of this study was to apply a novel scanning characterization approach, the BSE 3D image analysis, to study the pathological erosion on the surface of human incus bone involved by CHO, in order to definitely assess the eventual osteoclastic resorptive action. To do this, a comparison of BSE 3D image of resorption lacunae (resorption pits) from osteoporotic human femur neck (indubitably of osteoclastic origin) with that of the incus was performed. Surface parameters (area, mean depth, and volume) were calculated by the software Hitachi MountainsMap© from BSE 3D-reconstructed images; results were then statistically analyzed by SPSS statistical software. Our findings showed that no significant differences exist between the two groups. This quantitative approach implements the morphological characterization, allowing us to state that surface erosion of the incus is due to osteoclast action. Moreover, our observation and processing image workflow are the first in the literature showing the presence not only of bone erosion but also of matrix vesicles releasing their content on collagen bundles and self-immuring osteocytes, all markers of new bone formation on incus bone surface. On the basis of recent literature, it has been hypothesized that inflammatory environment induced by CHO may trigger the osteoclast activity, eliciting bone erosion. The observed new bone formation probably takes place at a slower rate in respect to the normal bone turnover, and the process is uncoupled (as recently demonstrated for several inflammatory diseases that promote bone loss) thus resulting in an overall bone loss. Novel scanning characterization approaches used in this study allowed for the first time the 3D imaging of incus bone erosion and its quantitative measurement, opening a new era of quantitative SEM morphology.

Toll-like receptor 7 regulates osteoclastogenesis in rheumatoid arthritis

This study aimed to determine the regulatory role of toll-like receptor 7 (TLR7) in receptor activator of nuclear factor kappa-B ligand (RANKL) production and osteoclast differentiation in rheumatoid arthritis (RA). In confocal microscopy, the co-expression of TLR7, CD55 and RANKL was determined in RA synovial fibroblasts. After RA synovial fibroblasts were treated with imiquimod, the RANKL gene expression and protein production were determined by real-time polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA). Osteoclastogenesis from peripheral blood CD14+ monocytes which were cultured with imiquimod was assessed by determining the numbers of tartrate-resistant acid phosphatase (TRAP)-positive multinucleated cells. The signal pathways mediating the TLR7-induced RANKL expression and osteoclastogenesis were analysed after inhibition of intracellular signal molecules and their phosphorylation. Imiquimod stimulated the expression of TLR7 and RANKL and production of RANKL in RA synovial fibroblasts, increasing the phosphorylation of TRAF6, IRF7, mitogen-activated protein kinases (MAPK), c-Jun and NFATc1. When CD14+ monocytes were cultured with imiquimod or co-cultured with imiquimod-pre-treated RA synovial fibroblasts, they were differentiated into TRAP+ multinucleated osteoclasts in the absence of RANKL. TLR7 activation-induced osteoclastogenesis in RA through direct induction of osteoclast differentiation from its precursors and up-regulation of RANKL production in RA synovial fibroblasts. Thus, the blockage of TLR7 pathway could be a promising therapeutic strategy for preventing bone destruction in RA.

Effects of Qingluo Tongbi Decoction on Gut Flora of Rats with Adjuvant-Induced Arthritis and the Underlying Mechanism

Rheumatoid arthritis (RA) is a common chronic systemic autoimmune disease. Recent studies show that gut flora plays an important role in regulating the systemic immune response, and gut dysbacteria are linked with systemic chronic inflammation in the development of RA. Our previous results found that Qingluo Tongbi decoction (QLT) can treat RA effectively. The present study explored the effect of QLT on gut flora in an adjuvant-induced arthritis (AA) rat model. Thirty rats were divided randomly into three groups: a control group, a model group, and a treatment group (n = 10 per group). The rats in the model group were injected with complete Freund's adjuvant (FCA), while the treatment group received FCA combined with QLT treatment. After 27 days, the gut flora was profiled by 16S rRNA gene sequencing. The levels of cadherin-11, IL-17α, TLR2, and TLR4 proteins in the synovial tissues were detected by western blotting (WB). The results showed that QLT treatment significantly inhibited raw swelling during the 15–27 d period compared with the model group. QLT treatment reversed the ten altered bacterial genera in the model group, and three families (Lachnospiraceae, Eubacteriaceae, and Leuconostocaceae) were closely related to QLT treatment based on linear discriminant analysis (LDA). Functional prediction showed seven types of predicted functions were related to the QLT treatment, and WB results showed that QLT treatment reversed the increased expression levels of cadherin-11, IL-17α, TLR2, and TLR4 in synovial tissues significantly. The expression levels of cadherin-11, IL-17α, and TLR2 correlated negatively with the abundance of Staphylococcus and Candidatus_Saccharimonas. Therefore, RA development was related to gut dysbiosis, and QLT effectively ameliorated RA with decreased inflammatory responses regulated by the gut flora.

Osteoclasts Modulate Bone Erosion in Cholesteatoma via RANKL Signaling

Cholesteatoma starts as a retraction of the tympanic membrane and expands into the middle ear, eroding the surrounding bone and causing hearing loss and other serious complications such as brain abscess and meningitis. Currently, the only effective treatment is complete surgical removal, but the recurrence rate is relatively high. In rheumatoid arthritis (RA), osteoclasts are known to be responsible for bone erosion and undergo differentiation and activation by receptor activator of NF-κB ligand (RANKL), which is secreted by synovial fibroblasts, T cells, and B cells. On the other hand, the mechanism of bone erosion in cholesteatoma is still controversial. In this study, we found that a significantly larger number of osteoclasts were observed on the eroded bone adjacent to cholesteatomas than in unaffected areas, and that fibroblasts in the cholesteatoma perimatrix expressed RANKL. We also investigated upstream transcription factors of RANKL using RNA sequencing results obtained via Ingenuity Pathways Analysis, a tool that identifies relevant targets in molecular biology systems. The concentrations of four candidate factors, namely interleukin-1β, interleukin-6, tumor necrosis factor α, and prostaglandin E2, were increased in cholesteatomas compared with normal skin. Furthermore, interleukin-1β was expressed in infiltrating inflammatory cells in the cholesteatoma perimatrix. This is the first report demonstrating that a larger-than-normal number of osteoclasts are present in cholesteatoma, and that the disease involves upregulation of factors related to osteoclast activation. Our study elucidates the molecular basis underlying bone erosion in cholesteatoma.

Effects of TLR-2/NF-κB signaling pathway on the occurrence of degenerative knee osteoarthritis: an in vivo and in vitro study

The study aims to explore the effects of TLR-2/NF-κB signaling pathway on the occurrence of degenerative knee osteoarthritis (OA). Degenerative knee OA and normal cartilage samples were collected from patients with degenerative knee OA receiving total knee arthroplasty and amputation. Expressions of TLR-2, NF-κB and MMP-13 were determined by qRT-PCR and immunochemistry. The chondrocytes were divided into control, IL-1β, IL-1β + anti-TLR-2 and IL-1β + PDTC groups. MTT assay and flow cytometry were performed to determine proliferation and apoptosis of the chondrocytes. Expressions of TLR-2, NF-κB and MMP-13 were measured by Western blotting. ELISA was conducted to detect the expressions of related inflammatory factors. The positive expressions of TLR, NF-κB and MMP13 were associated with body mass index (BMI), family history, exercise, and WOMAC scores of OA patients. Logistic regression analysis showed that OA influencing factors were TLR, NF-κB, MMP13, BMI, family history and exercise. Compared with normal chondrocytes, the expressions of TLR-2, NF-κB, MMP-13 and related inflammatory factors increased in degenerative knee OA. The chondrocytes in the IL-1β + anti-TLR-2 and IL-1β + PDTC groups showed lower apoptosis rates than those in the IL-1β group. Compared with the control group, increased expressions of TLR-2, NF-κB, phosphorylated-NF-κB (p-NF-κB), MMP-13, IL-1, IL-6 and TNF-α were found in the IL-1β group. In the IL-1β + anti-TLR-2 and IL-1β + PDTC groups, decreased expressions of NF-κB, p-NF-κB, MMP-13, IL-1, IL-6 and TNF-α were found compared with those in the IL-1β group. TLR-2/NF-κB signaling pathway contributes to the occurrence of degenerative knee OA.

Bergenin loaded gum xanthan stabilized silver nanoparticles suppress synovial inflammation through modulation of the immune response and oxidative stress in adjuvant induced arthritic rats

Bergenin (BG) is a naturally occurring C-glycoside with demonstrated anti-arthritic potential.

Promoter polymorphism (T-1486C) of TLR-9 gene is associated with knee osteoarthritis in a Turkish population

In this study, we aimed to determine whether TLR-9 T-1486C SNP was associated with susceptibility to OA in the Turkish population. The study group comprised 272 patients with Grade 2-3-4 knee OA according to the Kellgren-Lawrence scoring system and the control group was formed of 296 individuals with Grade 0-1. The TLR-9 genotype were assessed by real-time polymerase chain reaction. An analysis of TLR-9 promoter -1486T/C polymorphism revealed that the -1486CC genotype appeared to have a higher risk for OA and -1486TT and -1486CT genotypes have a protective effect against the development of OA (crude OR = 0.473, 95% CI = 0.297-0.754, p = 0.002, adjusted OR = 0.531, 95% CI = 0.326-0.864, p = 0.011). This study indicate that there is a correlation of TLR-9 T-1486C gene polymorphism with advanced knee OA in a Turkish population. Changed in TLR expression due to different allelles may cause osteoarthrith development outcome cartilage degeneration. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2484-2489, 2017.

TLRs, future potential therapeutic targets for RA

Toll like receptors (TLR)s have a central role in regulating innate immunity and in the last decade studies have begun to reveal their significance in potentiating autoimmune diseases such as rheumatoid arthritis (RA). Earlier investigations have highlighted the importance of TLR2 and TLR4 function in RA pathogenesis. In this review, we discuss the newer data that indicate roles for TLR5 and TLR7 in RA and its preclinical models. We evaluate the pathogenicity of TLRs in RA myeloid cells, synovial tissue fibroblasts, T cells, osteoclast progenitor cells and endothelial cells. These observations establish that ligation of TLRs can transform RA myeloid cells into M1 macrophages and that the inflammatory factors secreted from M1 and RA synovial tissue fibroblasts participate in TH-17 cell development. From the investigations conducted in RA preclinical models, we conclude that TLR-mediated inflammation can result in osteoclastic bone erosion by interconnecting the myeloid and TH-17 cell response to joint vascularization. In light of emerging unique aspects of TLR function, we summarize the novel approaches that are being tested to impair TLR activation in RA patients.

Major involvement of bacterial components in rheumatoid arthritis and its accompanying oxidative stress, systemic inflammation and hypercoagulability

We review the evidence that infectious agents, including those that become dormant within the host, have a major role to play in much of the etiology of rheumatoid arthritis and the inflammation that is its hallmark. This occurs in particular because they can produce cross-reactive (auto-)antigens, as well as potent inflammagens such as lipopolysaccharide that can themselves catalyze further inflammagenesis, including via β-amyloid formation. A series of observables coexist in many chronic, inflammatory diseases as well as rheumatoid arthritis. They include iron dysregulation, hypercoagulability, anomalous morphologies of host erythrocytes, and microparticle formation. Iron dysregulation may be responsible for the periodic regrowth and resuscitation of the dormant bacteria, with concomitant inflammagen production. The present systems biology analysis benefits from the philosophical idea of "coherence," that reflects the principle that if a series of ostensibly unrelated findings are brought together into a self-consistent narrative, that narrative is thereby strengthened. As such, we provide a coherent and testable narrative for the major involvement of (often dormant) bacteria in rheumatoid arthritis.

A Modified Glycosaminoglycan, GM-0111, Inhibits Molecular Signaling Involved in Periodontitis

Background

Periodontitis is characterized by microbial infection, inflammation, tissue breakdown, and accelerated loss of alveolar bone matrix. Treatment targeting these multiple stages of the disease provides ways to treat or prevent periodontitis. Certain glycosaminoglycans (GAGs) block multiple inflammatory mediators as well as suppress bacterial growth, suggesting that these GAGs may be exploited as a therapeutic for periodontitis.

Methods

We investigated the effects of a synthetic GAG, GM-0111, on various molecular events associated with periodontitis: growth of Porphyromonas gingivalis (P. gingivalis) and Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans) pathogenic bacteria associated with periodontitis; activation of pro-inflammatory signaling through TLR2 and TLR4 in mouse macrophage RAW 264.7 cells and heterologously expressed HEK 293 cells; osteoclast formation and bone matrix resorption in cultured mouse pre-osteoclasts.

Results

(1) GM-0111 suppressed the growth of P. gingivalis and A. actinomycetemcomitans even at 1% (w/v) solution. The antibacterial effects of GM-0111 were stronger than hyaluronic acid (HA) or xylitol in P. gingivalis at all concentrations and comparable to xylitol in A. actinomycetemcomitans at ≥2% (w/v) solution. We also observed that GM-0111 suppressed biofilm formation of P. gingivalis and these effects were much stronger than HA. (2) GM-0111 inhibited TLR-mediated pro-inflammatory cellular signaling both in macrophage and HEK 293 cells with higher selectivity for TLR2 than TLR4 (IC₅₀ of 1–10 ng/mL vs. > 100 μg/mL, respectively). (3) GM-0111 blocked RANKL-induced osteoclast formation (as low as 300 ng/mL) and bone matrix resorption. While GM-0111 showed high affinity binding to RANKL, it did not interfere with RANKL/RANK/NF-κB signaling, suggesting that GM-0111 inhibits osteoclast formation by a RANKL-RANK-independent mechanism.

Conclusions

We report that GM-0111 inhibits multiple molecular events involved in periodontitis, spanning from the early pro-inflammatory TLR signaling, to pathways activated at the later stage component of bone loss.

Evaluation of tool-like receptor-2 and 4 and interleukin-6 gene expressions in Turkish rheumatoid arthritis patients

Rheumatoid arthritis (RA) is a progressive inflammatory disease. Although the etiology and pathogenesis of RA are not known well, genetic and environmental factors are proposed to initiate an autoimmune process. We aimed to investigate mRNA expression levels of Toll-like receptor-2 (TLR-2), TLR-4, and interleukin-6 (IL-6) genes in RA disease. This study was conducted with 50 patients who were diagnosed with RA according to the American College of Rheumatology classification criteria for RA and 50 age-matched healthy control individuals who did not have any joint diseases and autoimmune diseases. We collected whole blood from all participants and analyzed expression of TLR-2, TLR-4, and IL-6 genes at mRNA level using real-time qPCR. TLR-2 expression was detected to increase 3.8-fold and IL-6 expression was detected to increase 6.8-fold in RA patients compared to healthy controls. No difference was found between patient and control groups with regard to TLR-4 expression. Overexpression of TLR-2 and IL-6 may be responsible for RA pathogenesis. Inhibition of both TLR and IL signaling pathways may prevent joint inflammation and destruction.

Hyaluronan Inhibits Tlr-4-Dependent RANKL Expression in Human Rheumatoid Arthritis Synovial Fibroblasts

The Toll-like receptor (TLR) signaling pathway is activated in synovial fibroblast cells in patients with rheumatoid arthritis (RA). The receptor activator of nuclear factor-κB (RANK) and its ligand, RANKL, are key molecules involved in the differentiation of osteoclasts and joint destruction in RA. Hyaluronan (HA) is a major extracellular component and an important immune regulator. In this study, we show that lipopolysaccharide (LPS) stimulation significantly increases RANKL expression via a TLR-4 signaling pathway. We also demonstrate that HA suppresses LPS-induced RANKL expression, which is dependent on CD44, but not intercellular adhesion molecule-1 (ICAM-1). Our study provides evidence for HA-mediated suppression of TLR-4-dependent RANKL expression. This could present an alternative target for the treatment of destructed joint bones and cartilages in RA.

Zn(2+) at a cellular crossroads

Zinc is an essential micronutrient for cellular homeostasis. Initially proposed to only contribute to cellular viability through structural roles and non-redox catalysis, advances in quantifying changes in nM and pM quantities of Zn(2+) have elucidated increasing functions as an important signaling molecule. This includes Zn(2+)-mediated regulation of transcription factors and subsequent protein expression, storage and release of intracellular compartments of zinc quanta into the extracellular space which modulates plasma membrane protein function, as well as intracellular signaling pathways which contribute to the immune response. This review highlights some recent advances in our understanding of zinc signaling.

The role of toll like receptors in giant cell arteritis

GCA is a common primary systemic vasculitis that results in granulomatous inflammation of medium to large arteries. Both innate and adaptive immune mechanisms combine to drive intimal hyperplasia, luminal stenosis and ultimately occlusion. While the pathogenesis of GCA is incompletely understood, the activation of resident adventitial dendritic cells via toll like receptors (TLRs) appears to be a crucial inciting event. Here we explore the role of TLRs in the pathogenesis of GCA, including their effects on dendritic cell and T cell activation and recruitment, putative infectious triggers for GCA and the potential of TLR inhibition as a novel therapeutic strategy in GCA.

The Role of the Transcriptional Regulation of Stromal Cells in Chronic Inflammation

Chronic inflammation is a common process connecting pathologies that vary in their etiology and pathogenesis such as cancer, autoimmune diseases, and infections. The response of the immune system to tissue damage involves a carefully choreographed series of cellular interactions between immune and non-immune cells. In recent years, it has become clear that stromal resident cells have an essential role perpetuating the inflammatory environment and dictating in many cases the outcome of inflammatory based pathologies. Signal transduction pathways remain the main focus of study to understand how stimuli contribute to perpetuating the inflammatory response, mainly due to their potential role as therapeutic targets. However, molecular events orchestrated in the nucleus by transcription factors add additional levels of complexity and may be equally important for understanding the phenotypic differences of activated stromal components during the chronic inflammatory process. In this review, we focus on the contribution of transcription factors to the selective regulation of inducible proinflammatory genes, with special attention given to the regulation of the stromal fibroblastic cell function and response.