Interplay between interferon and other cytokine systems in bone metabolism

Revealing the key role of cuproptosis in osteoporosis via the bioinformatic analysis and experimental validation of cuproptosis-related genes

The incidence of osteoporosis has rapidly increased owing to the ageing population. Cuproptosis, a novel mechanism that regulates cell death, may be a new therapeutic approach. However, the relevance of cuproptosis in the immune microenvironment and osteoporosis immunotherapy is still unknown. We intersected the differentially expressed genes from osteoporotic samples with 75 cuproptosis-related genes to identify 16 significantly expressed cuproptosis genes. We further explored the connection between the cuproptosis pattern, immune microenvironment, and immunotherapy. The weighted gene co-expression network analysis algorithm was used to identify cuproptosis phenotype-associated genes, and we used quantitative real-time PCR and immunohistochemistry in mouse femur tissues to verify hub gene (MAP2K2, FDX1, COX19, VEGFA, CDKN2A, and NFE2L2) expression. Six hub genes and 59 cuproptosis phenotype-associated genes involved in immunisation were identified among the osteoporosis and control groups, and the majority of these 59 genes were enriched in the inflammatory response, as well as in signal transducers, Janus kinase, and transcription pathway activators. In addition, two different clusters of cuproptosis were found, and immune infiltration analysis showed that gene Cluster 1 had a greater immune score and immune infiltration level. Further analysis revealed that three key genes (COX19, MAP2K2, and FDX1) were highly correlated with immune cell infiltration, and external experiments validated the association of these three genes with the prognosis of osteoporosis. We used the three key mRNAs COX19, MAP2K2, and FDX1 as a classification model that may systematically elucidate the complex connection between cuproptosis and the immune microenvironment of osteoporosis. New insights into osteoporosis pathogenesis and immunotherapy prospects may be gained from this study.

SREBP2 restricts osteoclast differentiation and activity by regulating IRF7 and limits inflammatory bone erosion

Osteoclasts are multinucleated bone-resorbing cells, and their formation is tightly regulated to prevent excessive bone loss. However, the mechanisms by which osteoclast formation is restricted remain incompletely determined. Here, we found that sterol regulatory element binding protein 2 (SREBP2) functions as a negative regulator of osteoclast formation and inflammatory bone loss. Cholesterols and SREBP2, a key transcription factor for cholesterol biosynthesis, increased in the late phase of osteoclastogenesis. The ablation of SREBP2 in myeloid cells resulted in increased in vivo and in vitro osteoclastogenesis, leading to low bone mass. Moreover, deletion of SREBP2 accelerated inflammatory bone destruction in murine inflammatory osteolysis and arthritis models. SREBP2-mediated regulation of osteoclastogenesis is independent of its canonical function in cholesterol biosynthesis but is mediated, in part, by its downstream target, interferon regulatory factor 7 (IRF7). Taken together, our study highlights a previously undescribed role of the SREBP2-IRF7 regulatory circuit as a negative feedback loop in osteoclast differentiation and represents a novel mechanism to restrain pathological bone destruction.

diABZI and poly(I:C) inhibit osteoclastic bone resorption by inducing IRF7 and IFIT3

Type I interferons (IFN-I) are pleiotropic factors endowed with multiple activities that play important roles in innate and adaptive immunity. Although many studies indicate that IFN-I inducers exert favorable effects on broad-spectrum antivirus, immunomodulation, and anti-tumor activities by inducing endogenous IFN-I and IFN-stimulated genes, their function in bone homeostasis still needs further exploration. Here, our study demonstrates 2 distinct IFN-I inducers, diABZI and poly(I:C), as potential therapeutics to alleviate osteolysis and osteoporosis. First, IFN-I inducers suppress the genes that control osteoclast (OC) differentiation and activity in vitro. Moreover, diABZI alleviates bone loss in Ti particle-induced osteolysis and ovariectomized -induced osteoporosis in vivo by inhibiting OC differentiation and function. In addition, the inhibitory effects of IFN-I inducers on OC differentiation are not observed in macrophages derived from Ifnar1-/-mice, which indicate that the suppressive effect of IFN-I inducers on OC is IFNAR-dependent. Mechanistically, RNAi-mediated silencing of IRF7 and IFIT3 in OC precursors impairs the suppressive effect of the IFN-I inducers on OC differentiation. Taken together, these results demonstrate that IFN-I inducers play a protective role in bone turnover by limiting osteoclastogenesis and bone resorption through the induction of OC-specific mediators via the IFN-I signaling pathway.

Osteoporosis: interferon-gamma-mediated bone remodeling in osteoimmunology

As the world population ages, osteoporosis, the most common disease of bone metabolism, affects more than 200 million people worldwide. The etiology is an imbalance in bone remodeling process resulting in more significant bone resorption than bone remodeling. With the advent of the osteoimmunology field, the immune system's role in skeletal pathologies is gradually being discovered. The cytokine interferon-gamma (IFN-γ), a member of the interferon family, is an important factor in the etiology and treatment of osteoporosis because it mediates bone remodeling. This review starts with bone remodeling process and includes the cellular and key signaling pathways of bone remodeling. The effects of IFN-γ on osteoblasts, osteoclasts, and bone mass are discussed separately, while the overall effects of IFN-γ on primary and secondary osteoporosis are summarized. The net effect of IFN-γ on bone appears to be highly dependent on the environment, dose, concentration, and stage of cellular differentiation. This review focuses on the mechanisms of bone remodeling and bone immunology, with a comprehensive discussion of the relationship between IFN-γ and osteoporosis. Finding the paradoxical balance of IFN-γ in bone immunology and exploring the potential of its clinical application provide new ideas for the clinical treatment of osteoporosis and drug development.

Suppression of IRF9 Promotes Osteoclast Differentiation by Decreased Ferroptosis via STAT3 Activation

Osteoporosis is a chronic disease that endangers the health of the elderly. Inhibiting osteoclast hyperactivity is a key aspect of osteoporosis prevention and treatment. Several studies have shown that interferon regulatory factor 9 (IRF9) not only regulates innate and adaptive immune responses but also plays an important role in inflammation, antiviral response, and cell development. However, the exact role of IRF9 in osteoclasts has not been reported. To elucidate the role of IRF9 in osteoclast differentiation, we established the ovariectomized mouse model of postmenopausal osteoporosis and found that IRF9 expression was reduced in ovariectomized mice with overactive osteoclasts. Furthermore, knockdown of IRF9 expression enhanced osteoclast differentiation in vitro. Using RNA sequencing, we identified that the differentially expressed genes enriched by IRF9 knockdown were related to ferroptosis. We observed that IRF9 knockdown promoted osteoclast differentiation via decreased ferroptosis in vitro and further verified that IRF9 knockdown reduced ferroptosis by activating signal transducer and activator of transcription 3 (STAT3) to promote osteoclastogenesis. In conclusion, we identified an essential role of IRF9 in the regulation of osteoclastogenesis in osteoporosis and its underlying mechanism.

Genetic Evidence Supporting a Causal Association Between mTOR-Dependent EIF-4E Circulating Protein Level and Osteoporosis

INTRODUCTION

The mechanistic target of rapamycin (mTOR) regulates bone homeostasis, a crucial factor in osteoporosis (OP) development. However, most research is based on observational studies, and the causality remains uncertain. Therefore, we analyzed two samples of mendelian randomization (MR) to determine whether there is a causal relationship between mTOR-dependent circulating proteins and OP.

METHODS

Mendelian weighting (weighted median [WM], inverse variance weighting [IVW], and MR-Egger regression) were applied to analyze the causality between bone phenotypes (bone mineral density [BMD] in forearm, femoral neck, lumbar spine, and heel) and mTOR-dependent circulating proteins (RP-S6K, 4EBP, EIF-4E, EIF-4A, and EIF-4G). Horizontal pleiotropy and heterogeneities were detected using Cochran's Q test, MR-Pleiotropy RE-Sidual Sum and Outlier (MR-PRESSO), and "leave-one-out" analysis. The proteomics-GWAS INTERVAL study was used to select the instrumental variables (IVs) for mTOR proteins.

RESULTS

As phenotypes for OP, estimations of BMD were taken in four different sites: forearm (FA) (n = 8143), femoral neck (FN) (n = 32,735), lumbar spine (LS) (n = 28,498), and heel (eBMD) (n = 426,824). Based on IVW analysis, EIF4E is causally related to FA-BMD (OR = 0.938, 95% CI 0.887, 0.991, p = 0.024) but not to BMD elsewhere.

CONCLUSION

MR analysis revealed a causal relationship between EIF-4E and FA-BMD, which may provide new insights into the underlying pathogenesis of OP and a new therapeutic target for OP.

Proteomics profiling of CD4 + T-cell-derived exosomes from patients with rheumatoid arthritis

OBJECTIVES

Our study profiled the CD4 + T-cell-derived exosomes from patients with rheumatoid arthritis (RA) using proteomics.

METHODS

Proteomic analysis of CD4 + T-cell-derived exosomes was performed by tandem mass tags (TMT) combined with LC-MS/MS. We validated the most significantly upregulated and downregulated proteins using ELISA and WB.

RESULTS

The proteomic results showed that there were 3 upregulated differentially expressed proteins and 31 downregulated differentially expressed proteins in the RA group. The results indicated that dihydropyrimidinase-related protein 3 (DPYSL3) was significantly upregulated in CD4 + T-cell-derived exosomes, whereas proteasome activator complex subunit 1 (PSME1) was significantly downregulated in the RA group. Bioinformatics analysis showed that proteins were enriched in "positive regulation of gene expression", "antigen processing and presentation", "acute-phase response" and "PI3K-AKT signaling" pathways. ELISA verified that compared to the control group, the RA group showed significant upregulation of DPYSL3, and downregulation of PSME1 in CD4 + T-cell-derived exosomes.

CONCLUSIONS

The proteomic analysis results of CD4 + T-cell-derived exosomes from patients with RA suggest that these differentially expressed proteins may be involved in RA pathogenesis. DPYSL3 and PSME1 may become useful biomarkers for RA.

The effect of cytokines on osteoblasts and osteoclasts in bone remodeling in osteoporosis: a review

The complicated connections and cross talk between the skeletal system and the immune system are attracting more attention, which is developing into the field of Osteoimmunology. In this field, cytokines that are among osteoblasts and osteoclasts play a critical role in bone remodeling, which is a pathological process in the pathogenesis and development of osteoporosis. Those cytokines include the tumor necrosis factor (TNF) family, the interleukin (IL) family, interferon (IFN), chemokines, and so on, most of which influence the bone microenvironment, osteoblasts, and osteoclasts. This review summarizes the effect of cytokines on osteoblasts and osteoclasts in bone remodeling in osteoporosis, aiming to providing the latest reference to the role of immunology in osteoporosis.

Induction of protective interferon-β responses in murine osteoblasts following Staphylococcus aureus infection

Introduction

The refractory and recurrent nature of chronic staphylococcal osteomyelitis may be due, at least in part, to the ability of Staphylococcus aureus to invade and persist within bone-forming osteoblasts. However, osteoblasts are now recognized to respond to S. aureus infection and produce numerous immune mediators and bone regulatory factors that can shape the host response. Type I interferons (IFNs) are best known for their antiviral effects, but it is becoming apparent that they impact host susceptibility to a wide range of pathogens including S. aureus.

Methods

Here, we have assessed the local expression of IFN-β by specific capture ELISA in an established in vivo mouse model of staphylococcal osteomyelitis. RNA Tag-Seq analysis, specific capture ELISAs, and/or immunoblot analyses, were then used to assess the expression of type I IFNs and select IFN stimulated genes (ISGs) in S. aureus infected primary murine osteoblasts. The effect of IFN-β on intracellular S. aureus burden was assessed in vitro following recombinant cytokine treatment by serial colony counts of liberated bacteria.

Results

We report the presence of markedly elevated IFN-β levels in infected bone tissue in a mouse model of staphylococcal osteomyelitis. RNA Tag-Seq analysis of S. aureus infected osteoblasts showed enrichment of genes associated with type I IFN signaling and ISGs, and elevated expression of mRNA encoding IFN-β and ISG products. IFN-β production was confirmed with the demonstration that S. aureus induces its rapid and robust release by osteoblasts in a dose-dependent manner. Furthermore, we showed increased protein expression of the ISG products IFIT1 and IFIT3 by infected osteoblasts and demonstrate that this occurs secondary to the release of IFN-β by these cells. Finally, we have determined that exposure of S. aureus-infected osteoblasts to IFN-β markedly reduces the number of viable bacteria harbored by these cells.

Discussion

Together, these findings indicate an ability of osteoblasts to respond to bacteria by producing IFN-β that can act in an autocrine and/or paracrine manner to elicit ISG expression and mitigate S. aureus infection.

Immune mechanism of low bone mineral density caused by ankylosing spondylitis based on bioinformatics and machine learning

Background and Objective: This study aims to find the key immune genes and mechanisms of low bone mineral density (LBMD) in ankylosing spondylitis (AS) patients. Methods: AS and LBMD datasets were downloaded from the GEO database, and differential expression gene analysis was performed to obtain DEGs. Immune-related genes (IRGs) were obtained from ImmPort. Overlapping DEGs and IRGs got I-DEGs. Pearson coefficients were used to calculate DEGs and IRGs correlations in the AS and LBMD datasets. Louvain community discovery was used to cluster the co-expression network to get gene modules. The module most related to the immune module was defined as the key module. Metascape was used for enrichment analysis of key modules. Further, I-DEGs with the same trend in AS and LBMD were considered key I-DEGs. Multiple machine learning methods were used to construct diagnostic models based on key I-DEGs. IID database was used to find the context of I-DEGs, especially in the skeletal system. Gene-biological process and gene-pathway networks were constructed based on key I-DEGs. In addition, immune infiltration was analyzed on the AS dataset using the CIBERSORT algorithm. Results: A total of 19 genes were identified I-DEGs, of which IFNAR1, PIK3CG, PTGER2, TNF, and CCL3 were considered the key I-DEGs. These key I-DEGs had a good relationship with the hub genes of key modules. Multiple machine learning showed that key I-DEGs, as a signature, had an excellent diagnostic performance in both AS and LBMD, and the SVM model had the highest AUC value. Key I-DEGs were closely linked through bridge genes, especially in the skeletal system. Pathway analysis showed that PIK3CG, IFNAR1, CCL3, and TNF participated in NETs formation through pathways such as the MAPK signaling pathway. Immune infiltration analysis showed neutrophils had the most significant differences between case and control groups and a good correlation with key I-DEG. Conclusion: The key I-DEGs, TNF, CCL3, PIK3CG, PTGER2, and IFNAR1, can be utilized as biomarkers to determine the risk of LBMD in AS patients. They may affect neutrophil infiltration and NETs formation to influence the bone remodeling process in AS.

Up-regulated IL-17 and Tnf signaling in bone marrow cells of young male osteogenesis imperfecta mice

Osteogenesis imperfecta (OI) is a congenital bone dysplasia mainly caused by either defective production or assembly of type I collagen. The skeletal phenotypes especially fractures are often seen in OI adolescents. Studies have found that an increased number of osteoclasts and excessive bone resorption existed in collagen-related OI, which has not been well understood. Emerging evidence has suggested that inflammation may be associated with OI. We speculated that the bone marrow (BM) niche had similar inflammatory changes and performed RNA-sequencing (RNA-seq) in BM cells derived from young male mice to analyze the related differentially expressed genes (DEGs) and pathways. Data showed that there were 117 shared DEGs (Q ≤ 0.05, |log₂FC| ≥ 1) in BM cells isolated from two types of OI murine models that respectively simulate different OI types. Gene Ontology (GO) (Q ≤ 0.05) analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) (Q ≤ 0.05) analysis and real-time PCR validation indicated the dysregulated biology process of cellular response to interferon (Ifn) together with upregulated IL-17 signaling, tumor necrosis factor (Tnf) signaling and osteoclast differentiation in OI BM niche. Either defective collagen production or abnormal collagen assembly shared similar alterations in gene profiles and pathways involving inflammation and osteoclast activation. Data presented here not only contributed to understanding of the mechanism of the enhanced bone absorption in the bones of OI, but also provided more evidence to develop potential anti-inflammation therapies.

Correlation between gene expression and MRI STIR signals in patients with chronic low back pain and Modic changes indicates immune involvement

Disability and distress caused by chronic low back pain (LBP) lacking clear pathoanatomical explanations cause huge problems both for patients and society. A subgroup of patients has Modic changes (MC), identifiable by MRI as vertebral bone marrow lesions. The cause of such changes and their relationship to pain are not yet understood. We explored the pathobiology of these lesions using profiling of gene expression in blood, coupled with an edema-sensitive MRI technique known as short tau inversion recovery (STIR) imaging. STIR images and total RNA from blood were collected from 96 patients with chronic LBP and MC type I, the most inflammatory MC state. We found the expression of 37 genes significantly associated with STIR signal volume, ten genes with edema abundancy (a constructed combination of STIR signal volume, height, and intensity), and one gene with expression levels significantly associated with maximum STIR signal intensity. Gene sets related to interferon signaling, mitochondrial metabolism and defense response to virus were identified as significantly enriched among the upregulated genes in all three analyses. Our results point to inflammation and immunological defense as important players in MC biology in patients with chronic LBP.

Interferon-γ induces interleukin-6 production by neutrophils via the Janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathway

Objective

Interferon-gamma (IFN-γ) is overexpressed in rheumatoid synovium and thought to be involved in the pathogenesis of rheumatoid arthritis (RA). In this study, we examined our hypothesis that IFN-γ activates innate immune cells and upregulates inflammatory cytokines. Peripheral blood neutrophils were stimulated with IFN-γ in the presence or absence of Janus kinase (JAK) inhibitors. Interleukin-6 (IL-6) mRNA and protein expression were analyzed using real-time polymerase chain reaction (PCR) method and enzyme-linked immunosorbent assay. Protein phosphorylation of JAKs or STAT1 was assessed by Western blot using phospho-specific antibodies.

Results

IFN-γ stimulation induces IL-6 expression in protein and mRNA levels in human neutrophils. Furthermore, IFN-γ stimulation induces JAK1/JAK2 phosphorylation and downstream signal transducer and activator of transcription (STAT) 1 phosphorylation in human neutrophils. Although all JAKi, blocked IFN-γ-induced JAK1.2/STAT1 phosphorylation at higher concentrations (100 nM), baricitinib most efficiently inhibited IFN-γ-induced JAK1.2/STAT1 phosphorylation at lower concentrations (≤ 25 nM). Among these JAKi, baricitinib was the most potent regulator for IFN-γ-induced IL-6 production in human neutrophils. Our data indicate that IFN-γ upregulates IL-6 production via the JAK1/2-STAT1 pathway in human innate immune cells. Furthermore, this IFN-γ-mediated IL-6 induction via JAK/STAT was downregulated by JAKi.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13104-021-05860-w.

Effects of Hepatitis C Virus (HCV) Eradication on Bone Mineral Density in Human Immunodeficiency Virus/HCV-Coinfected Patients

BACKGROUND

Little is known about the effects of eradication of hepatitis C virus (HCV) on bone mineral density (BMD) and biomarkers of bone remodeling in human immunodeficiency virus (HIV)/HCV-coinfected patients.

METHODS

We prospectively assessed standardized BMD (sBMD) at the lumbar spine and femoral neck, World Health Organization BMD categories at both sites, and plasma concentrations of soluble receptor activator of NF-κβ ligand (sRANKL), and osteoprotegerin (OPG) at baseline (the date of initiation of anti-HCV therapy) and at 96 weeks.

RESULTS

A total of 238 patients were included. The median age was 49.5 years, 76.5% were males, 48.3% had cirrhosis, 98.3% were on antiretroviral therapy, median CD4+ cell count was 527 cells/μL, and 86.6% had HIV-1 RNA <50 copies/mL. The prevalence of osteoporosis at baseline at the lumbar spine (LS) and femoral neck (FN) was 17.6% and 7.2%, respectively. Anti-HCV therapy comprised pegylated interferon (peg-IFN) and ribavirin (RBV) plus 1 direct-acting antiviral in 53.4%, peg-IFN/RBV in 34.5%, and sofosbuvir/RBV in 12.2%. A total of 145 (60.9%) patients achieved sustained virologic response (SVR). No significant effect of SVR was observed on sBMD for the interaction between time and SVR either in the LS (P = .801) or the FN (P = .911). Likewise, no significant effect of SVR was observed in plasma levels of sRANKL (P = .205), OPG (P = .249), or sRANKL/OPG ratio (P = .123) for the interaction between time and SVR. No significant correlation was found between fibrosis by transient elastography, and LS and FN sBMD, at baseline and week 96.

CONCLUSIONS

SVR was not associated with significant changes in BMD nor biomarkers of bone remodeling in HIV/HCV-coinfected persons.

Osteoclast fusion and bone loss are restricted by interferon inducible guanylate binding proteins

Chronic inflammation during many diseases is associated with bone loss. While interferons (IFNs) are often inhibitory to osteoclast formation, the complex role that IFN and interferon-stimulated genes (ISGs) play in osteoimmunology during inflammatory diseases is still poorly understood. We show that mice deficient in IFN signaling components including IFN alpha and beta receptor 1 (IFNAR1), interferon regulatory factor 1 (IRF1), IRF9, and STAT1 each have reduced bone density and increased osteoclastogenesis compared to wild type mice. The IFN-inducible guanylate-binding proteins (GBPs) on mouse chromosome 3 (GBP1, GBP2, GBP3, GBP5, GBP7) are required to negatively regulate age-associated bone loss and osteoclastogenesis. Mechanistically, GBP2 and GBP5 both negatively regulate in vitro osteoclast differentiation, and loss of GBP5, but not GBP2, results in greater age-associated bone loss in mice. Moreover, mice deficient in GBP5 or chromosome 3 GBPs have greater LPS-mediated inflammatory bone loss compared to wild type mice. Overall, we find that GBP5 contributes to restricting age-associated and inflammation-induced bone loss by negatively regulating osteoclastogenesis.

Modulating macrophage activities to promote endogenous bone regeneration: Biological mechanisms and engineering approaches

A coordinated interaction between osteogenesis and osteoimmune microenvironment is essential for successful bone healing. In particular, macrophages play a central regulatory role in all stages of bone repair. Depending on the signals they sense, these highly plastic cells can mediate the host immune response against the exterior signals of molecular stimuli and implanted scaffolds, to exert regenerative potency to a varying extent. In this article, we first encapsulate the immunomodulatory functions of macrophages during bone regeneration into three aspects, as sweeper, mediator and instructor. We introduce the phagocytic role of macrophages in different bone healing periods ('sweeper') and overview a variety of paracrine cytokines released by macrophages either mediating cell mobilisation, vascularisation and matrix remodelling ('mediator'), or directly driving the osteogenic differentiation of bone progenitors and bone repair ('instructor'). Then, we systematically classify and discuss the emerging engineering strategies to recruit, activate and modulate the phenotype transition of macrophages, to exploit the power of endogenous macrophages to enhance the performance of engineered bone tissue.

The Dramatic Role of IFN Family in Aberrant Inflammatory Osteolysis

Skeletal system has been considered a highly dynamic system, in which bone-forming osteoblasts and bone-resorbing osteoclasts go through a continuous remodeling cycle to maintain homeostasis of bone matrix. It has been well acknowledged that interferons (IFNs), acting as a subgroup of cytokines, not only have crucial effects on regulating immunology but also could modulate the dynamic balance of bone matrix. In the light of different isoforms, IFNs have been divided into three major categories in terms of amino acid sequences, recognition of specific receptors and biological activities. Currently, type I IFNs consist of a multi-gene family with several subtypes, of which IFN-α exerts pro-osteoblastogenic effects to activate osteoblast differentiation and inhibits osteoclast fusion to maintain bone matrix integrity. Meanwhile, IFN-β suppresses osteoblast-mediated bone remodeling as well as exhibits inhibitory effects on osteoclast differentiation to attenuate bone resorption. Type II IFN constitutes the only type, IFN-γ, which exerts regulatory effects on osteoclastic bone resorption and osteoblastic bone formation by biphasic ways. Interestingly, type III IFNs are regarded as new members of IFN family composed of four members, including IFN-λ1 (IL-29), IFN-λ2 (IL-28A), IFN-λ3 (IL-28B) and IFN-λ4, which have been certified to participate in bone destruction. However, the direct regulatory mechanisms underlying how type III IFNs modulate the metabolic balance of bone matrix, remains poorly elucidated. In this review, we have summarized functions of IFN family during physiological and pathological conditions and described the mechanisms by which IFNs maintain bone matrix homeostasis via affecting the osteoclast-osteoblast crosstalk. In addition, the potential therapeutic effects of IFNs on inflammatory bone destruction diseases such as rheumatoid arthritis (RA), osteoarthritis (OA) and infectious bone diseases are also well displayed, which are based on the predominant role of IFNs in modulating the dynamic equilibrium of bone matrix.

The Role of the Immune Microenvironment in Bone Regeneration

Bone is an active tissue, being constantly renewed in healthy individuals with participation of the immune system to a large extent. Any imbalance between the processes of bone formation and bone resorption is linked to various inflammatory bone diseases. The immune system plays an important role in tissue formation and bone resorption. Recently, many studies have demonstrated complex interactions between the immune and skeletal systems. Both of immune cells and cytokines contribute to the regulation of bone homeostasis, and bone cells, including osteoblasts, osteoclasts, osteocytes, also influence the cellular functions of immune cells. These crosstalk mechanisms between the bone and immune system finally emerged, forming a new field of research called osteoimmunology. Therefore, the immune microenvironment is crucial in determining the speed and outcome of bone healing, repair, and regeneration. In this review, we summarise the role of the immune microenvironment in bone regeneration from the aspects of immune cells and immune cytokines. The elucidation of immune mechanisms involved in the process of bone regeneration would provide new therapeutic targets for improving the curative effects of bone injury treatment.

Extracellular microvesicles that originated adipose tissue derived mesenchymal stem cells have the potential ability to improve rheumatoid arthritis on mice

Introduction

Mesenchymal stem cells (MSCs) are promising therapeutic tools in regenerative medicine. In particularly adipose tissue derived MSC (AMSC) has powerful potential for the therapeutics of rheumatoid arthritis (RA) because these cells can control immune balance. RA systemically occurs autoimmune disease. Interestingly, IL-1 receptor antagonist deficient (IL-1ra^-/-) mice induce inflammation in joints like RA. In RA therapy, although AMSC improves the inflammation activity, it is little known to play roles of extracellular microvesicles (EV) for improvement of RA. To clarify the MSC-derived EVs are involved amelioration mechanisms for RA by themselves, we examined the functional effects of development for RA by AMSC-EVs.

Methods

We isolated AMSCs derived mice adipose tissue and purified EVs from the culture supernatant of AMSCs. To examine whether EVs can improve RA, we administrated EVs or AMSCs to IL-1ra knockout mice as RA model mice. We analyzed EVs-included factor by western blot methods and RA improvement effect by ELISA.

Results

In this study, we showed that the swellings of joints on mice in wild type AMSC and that in AMSC-EVs decreased than that in IL-1ra^-/- mice-AMSC-EVs and in none-treated. We detected IL-1ra expression in AMSC-EVs in wild type mice but not that in IL-1ra^-/- mice. Proinflammatory cytokine expression changes in mice showed in AMSCs and AMSC-EVs, but no apparent differences cytokine expressions were detected in IL-1ra^-/- mice.

Conclusions

In this study, we concluded that MSCs might improve RA by the transferring of factors such as IL-1ra, which are included their MSC derived- EVs.

Antipostmenopausal effects of Stauntonia hexaphylla and Vaccinium bracteatum fruit combination in estrogen-deficient rats

Background

Climacterium is a series of physical and mental symptoms occurring in women and men due to decreased levels of sex hormones. Women lose the ability to become pregnant due to decreased ovarian estrogen production; the initial symptom being hot flushes. In addition, urogenital atrophy, sexual dysfunction, mood changes, and osteoporosis occur. Extracts of Stauntonia hexaphylla (SH) and Vaccinium bracteatum (VB) fruits, with a wide range of biological activities, are widely used in traditional herbal medicine.

Objective

The purpose of this study was to investigate the mitigation of menopausal symptoms, such as hot flushes and postmenopausal osteoporosis after combinatorial treatment with SH and VB (SHVB) of ovariectomized (OVX) rats.

Design

We measured the bone regenerative effect of SHVB on receptor activator of nuclear factor-κB (NF-κB) ligand-induced osteoclast differentiation in vitro and on ovariectomy-induced osteoporosis in vivo. We investigated the effect of SHVB in a rat model of menopausal hot flushes, in which the tail skin temperature increases following ovariectomy-induced rapid decline in estrogen levels.

Results

SHVB inhibited osteoclast formation and tartrate-resistant acid phosphatase activity in primary mouse bone marrow-derived cells. In an estrogen deficiency-induced rat model, measurement of serum bone turnover factors showed that treatment with SHVB lowered the increased bone turnover. Additionally, SHVB decreased OVX-induced bone loss of the total femur. SHVB inhibited osteoclast differentiation, prevented bone mass reduction, and improved trabecular bone structure and biochemical markers in OVX-induced osteoporosis. In addition, administration of SHVB significantly ameliorated the changes in skin temperature in OVX rats.

Conclusion

SHVB improved the symptoms of menopause. These results provide the foundation for developing SHVB as a natural substance to replace hormones in the future.

Oral Microbiome and Gingival Tissue Apoptosis and Autophagy Transcriptomics

Objective: This study focused on documenting characteristics of the gingival transcriptome during various stages of periodontitis targeting genes associated with apoptotic and autophagic pathways and changes that specifically associate with features of the oral microbiome.

Methods:Macaca mulatta (n = 18; 12–23 years) were examined at baseline and 0.5, 1, and 3 months of disease progression, as well as 5 months with clinical disease resolution. 16S sequencing and microarray analyses examined changes in the microbiome and gingival transcriptome, respectively, at each time point from every animal.

Results: Specific patterns of apoptotic and autophagic genes were identified related to the initiation and progression of disease. The analysis also provided insights on the principal bacteria within the complex microbiome whose abundance was significantly correlated with differences in apoptotic and autophagic gene expression. Bacteria were identified that formed associated complexes with similar effects on the host gene expression profiles. A complex of Leptotrichia_unclassifed, Capnocytophaga_unclassified, Prevotella sp. 317, and Veillonellaceae_[G-1] sp. 155 were significantly negatively correlated with both apoptosis and autophagy. Whereas, Veillonellaceae_[G-1], Porphyromonadaceae, and F. alocis 539 were significantly positively correlated with both pathways, albeit this relationship was primarily associated with pro-apoptotic genes.

Conclusions: The findings provide evidence for specific bacteria/bacterial complexes within the oral microbiome that appear to have a more substantive effect on regulating apoptotic and autophagic pathways in the gingival tissues with periodontitis.

The correlation between the Th17/Treg cell balance and bone health

With the ageing of the world population, osteoporosis has become a problem affecting quality of life. According to the traditional view, the causes of osteoporosis mainly include endocrine disorders, metabolic disorders and mechanical factors. However, in recent years, the immune system and immune factors have been shown to play important roles in the occurrence and development of osteoporosis. Among these components, regulatory T (Treg) cells and T helper 17 (Th17) cells are crucial for maintaining bone homeostasis, especially osteoclast differentiation. Treg cells and Th17 cells originate from the same precursor cells, and their differentiation requires involvement of the TGF-β regulated signalling pathway. Treg cells and Th17 cells have opposite functions. Treg cells inhibit the differentiation of osteoclasts in vivo and in vitro, while Th17 cells promote the differentiation of osteoclasts. Therefore, understanding the balance between Treg cells and Th17 cells is anticipated to provide a new idea for the development of novel treatments for osteoporosis.

Identification and Analysis of Genes Underlying Bone Mineral Density by Integrating Microarray Data of Osteoporosis

Osteoporosis is a kind of brittle bone disease, which is characterized by a reduction in bone mineral density (BMD). In recent years, a number of genes and pathophysiological mechanisms have been identified for osteoporosis. However, the genes associated with BMD remain to be explored. Toward this end, we integrated multiple osteoporosis microarray datasets to identify and systematically characterize BMD-related genes. By integrating the differentially expressed genes from three osteoporosis microarray datasets, 152 genes show differentially expressed between high and low BMD osteoporosis samples in at least two of the three datasets. Among them, 88 were up-regulated in high BMD samples and 64 were up-regulated in low BMD samples. The expression of ZFP36, JUNB and TMEM8A were increased at high BMD samples in all three datasets. Hub genes were further identified by co-expression network analysis. Functional enrichment analysis showed that the gene up-regulated in high BMD were enriched in immune-related functions, suggesting that the immune system plays an important role in osteoporosis. Our study explored BMD-related genes based on the integration of osteoporosis microarray data, providing guidance to other researchers from a new perspective.

Intrinsic Type 1 Interferon (IFN1) Profile of Uncultured Human Bone Marrow CD45lowCD271+ Multipotential Stromal Cells (BM-MSCs): The Impact of Donor Age, Culture Expansion and IFNα and IFNβ Stimulation

Skeletal aging is associated with reduced proliferative potential of bone marrow (BM) multipotential stromal cells (MSCs). Recent data suggest the involvement of type 1 interferon (IFN1) signalling in hematopoietic stem cell (HSC) senescence. Considering that BM-HSCs and BM-MSCs share the same BM niche, we investigated IFN1 expression profile in human BM-MSCs in relation to donor age, culture-expansion and IFN1 (α and β) stimulation. Fluorescence-activated cell sorting was used to purify uncultured BM-MSCs from younger (19-41, n = 6) and older (59-89, n = 6) donors based on the CD45^lowCD271⁺ phenotype, and hematopoietic-lineage cells (BM-HLCs, CD45⁺CD271^-) were used as controls. Gene expression was analysed using integrated circuits arrays in sorted fractions as well as cultured/stimulated BM-MSCs and Y201/Y202 immortalised cell lines. IFN1 stimulation led to BM-MSC growth arrest and upregulation of many IFN1-stimulated genes (ISGs), with IFNβ demonstrating stronger effects. Uncultured MSCs were characterised by a moderate-level ISG expression similar to Y201 cells. Age-related changes in ISG expression were negligible in BM-MSCs compared to BM-HLCs, and intracellular reactive oxygen species (ROS) levels in BM-MSCs did not significantly correlate with donor age. Antiaging genes Klotho and SIRT6 correlated with more ISGs in BM-MSCs than in BM-HLCs. In patients with osteoarthritis (OA), BM-MSCs expressed considerably lower levels of several ISGs, indicating that their IFN1 signature is affected in a pathological condition. In summary, BM-MSCs possess homeostatic IFN1 gene expression signature in health, which is sensitive to in vitro culture and external IFN1 stimulation. IFN signalling may facilitate in vivo BM-MSC responses to DNA damage and combating senescence and aberrant immune activation.

Ovariectomy Activates Chronic Low-Grade Inflammation Mediated by Memory T Cells, Which Promotes Osteoporosis in Mice

The loss of estrogen (E₂ ) initiates a rapid phase of bone loss leading to osteoporosis in one-half of postmenopausal women, but the mechanism is not fully understood. Here, we show for the first time how loss of E₂ activates low-grade inflammation to promote the acute phase of bone catabolic activity in ovariectomized (OVX) mice. E₂ regulates the abundance of dendritic cells (DCs) that express IL-7 and IL-15 by inducing the Fas ligand (FasL) and apoptosis of the DC. In the absence of E₂ , DCs become long-lived, leading to increased IL-7 and IL-15. We find that IL-7 and IL-15 together, but not alone, induced antigen-independent production of IL-17A and TNFα in a subset of memory T cells (T_MEM ). OVX of mice with T-cell-specific ablation of IL15RA showed no IL-17A and TNFα expression, and no increase in bone resorption or bone loss, confirming the role of IL-15 in activating the T_MEM and the need for inflammation. Our results provide a new mechanism by which E₂ regulates the immune system, and how menopause leads to osteoporosis. The low-grade inflammation is likely to cause or contribute to other comorbidities observed postmenopause. © 2020 American Society for Bone and Mineral Research.

TBX21-1993T/C polymorphism association with Th1 and Th17 response at periapex and with periapical lesions development risk

TBX21-1993T/C (rs4794067) polymorphism increases the transcriptional activity of the Tbx21, essential for interferon gamma (IFNg) transcription, but its functional impact on development Th1- response in vivo remains unclear, as well its potential influence over inflammatory osteolytic conditions, such as periapical lesions. Therefore, this study comprises a case-control and functional investigation of Tbx21 genetic variations impact on Th1 response in vivo and in vitro, and its impact on periapical lesions risk and outcome, performed with a population of healthy controls (H; N = 283) and patients presenting periapical lesions (L; N = 188) or deep caries (DC; N = 152). TBX21-1993T/C genotyping demonstrated that the polymorphic allele C, as well TC/TC+CC genotypes, was significantly less frequent in the L patients compared to H and DC groups. Additionally, gene expression analysis demonstrates that T-cell-specific T-box transcription factor (Tbet) and IFNg transcripts levels were downregulated whereas IL-17 levels were upregulated in the TBX21-1993 C carriers (TC/TC+CC) in comparison with the TT group. Also, while TT and TC+CC genotypes are equally prevalent in the lesions presenting low IFN/IL17 ratio, a significant decrease in polymorphic TC+CC genotypes was observed in lesions presenting intermediate and high IFN/IL17 ratio. In vitro experiments confirmed the predisposition to Th1 polarization associated with TBX21-1993, since PBMC CD4 T cells from T allele carriers produce higher IFNg levels upon CD3/CD28 stimulation than the C group, in both standard/neutral and Th1-polarizing culture conditions. In conclusion, the TBX21-1993 T allele and TC/CC genotypes predispose to Th1-type immune response development in vitro, influence immune response polarization in vivo, and consequently account for the risk for apical periodontitis development.

Bone loss in MPTP mouse model of Parkinson's disease is triggered by decreased osteoblastogenesis and increased osteoclastogenesis

Bone loss is a non-motor symptom of Parkinson's disease (PD). It is unclear whether a patient's immobility or the endocrine changes in the body causes bone deterioration. To address this issue, we used an animal model of the disease where Swiss albino mice were injected with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) on day 1 and were left untreated for eight weeks. Behavioral phenotypes of PD, and striatal acetylcholinesterase and dopamine levels were measured. Cortical and trabecular bones were assessed by μ-CT and histology. Gene expression studies were done through quantitative real-time PCR. Effect of MPP+ and MPTP-treated mice serum on MC3T3E-1, SH-SY5Y, and primary osteoclast cells were also studied. Our results demonstrated that MPTP treatment leads to PD like symptoms. It shows a loss of trabecular bone mass and quality by decreasing osteoblast and increased osteoclast number and activity. This effect was accompanied by reduced osteogenic and elevated osteoclastogenic genes expression. While MPP+ had a cytotoxic effect on dopaminergic neurons, it did not affect bone cells. However, ex-vivo treatment of the serum from MPTP-treated mice decreased osteoblastogenesis and increased osteoclastogenesis in cell culture. In conclusion, our study suggests that MPTP-induced parkinsonian features in mice leads to trabecular bone loss by decreased bone formation and increased bone resorption due to changes in the serum circulating factors. This study characterizes the microarchitectural and cellular changes in the skeleton of a mouse model of PD that can be further utilized to investigate therapeutic avenues to treat bone loss in PD patients.

PRMT5 inhibition promotes osteogenic differentiation of mesenchymal stromal cells and represses basal interferon stimulated gene expression

Protein arginine methyltransferases (PRMTs) catalyze symmetric and asymmetric methylation on arginine residues of multiple protein targets including histones and have essential roles in organismal development and disease. PRMT5 mediates symmetric di-methylation (sDMA) of arginine 2 (H3R2me2s) and arginine 8 on histone 3 (H3R8me2s), arginine 3 on histones 2A and 4 (H2A/H4R3me2s) as well as several non-histone substrates like Sm proteins. Here, we found that selective inhibition of PRMT5 in mesenchymal stromal cells (MSCs) led to a reduction in colony forming units (CFUs) and increased osteoblast differentiation. PRMT5 inhibition blocked global symmetric dimethylation of H3R8 and H4R3 but not on H3R2. Genome-wide expression analysis by total RNA sequencing of mesenchymal stromal cells undergoing osteogenic differentiation revealed significant reduction in the intrinsic expression of several interferon-stimulated genes (ISGs) upon PRMT5 inhibition. Effects of PRMT5 inhibition on basal ISG expression and osteogenic differentiation was effectively blocked by exogenous activation of type I IFN signaling. Together, these results indicate important functions for PRMT5 in the regulation of basal interferon gene expression in MSCs and in the control of differentiation potential of MSCs during osteogenic differentiation.

C5aR1 interacts with TLR2 in osteoblasts and stimulates the osteoclast-inducing chemokine CXCL10

The anaphylatoxin C5a is generated upon activation of the complement system, a crucial arm of innate immunity. C5a mediates proinflammatory actions via the C5a receptor C5aR1 and thereby promotes host defence, but also modulates tissue homeostasis. There is evidence that the C5a/C5aR1 axis is critically involved both in physiological bone turnover and in inflammatory conditions affecting bone, including osteoarthritis, periodontitis, and bone fractures. C5a induces the migration and secretion of proinflammatory cytokines of osteoblasts. However, the underlying mechanisms remain elusive. Therefore, in this study we aimed to determine C5a‐mediated downstream signalling in osteoblasts. Using a whole‐genome microarray approach, we demonstrate that C5a activates mitogen‐activated protein kinases (MAPKs) and regulates the expression of genes involved in pathways related to insulin, transforming growth factor‐β and the activator protein‐1 transcription factor. Interestingly, using coimmunoprecipitation, we found an interaction between C5aR1 and Toll‐like receptor 2 (TLR2) in osteoblasts. The C5aR1‐ and TLR2‐signalling pathways converge on the activation of p38 MAPK and the generation of C‐X‐C motif chemokine 10, which functions, among others, as an osteoclastogenic factor. In conclusion, C5a‐stimulated osteoblasts might modulate osteoclast activity and contribute to immunomodulation in inflammatory bone disorders.

Genome-wide association study provides insights into genes related with horn development in Nelore beef cattle

The causal mutation for polledness in Nelore (Bos taurus indicus) breed seems to have appeared first in Brazil in 1957. The expression of the polled trait is known to be ruled by a few groups of alleles in taurine breeds; however, the genetic basis of this trait in indicine cattle is still unclear. The aim of this study was to identify genomic regions associated with the hornless trait in a commercial Nelore population. A total of 107,294 animals had phenotypes recorded and 2,238 were genotyped/imputed for 777k SNP. The weighted single-step approach for genome-wide association study (WssGWAS) was used to estimate the SNP effects and variances accounted for by 1 Mb sliding SNP windows. A centromeric region of chromosome 1 with 3.11 Mb size (BTA1: 878,631–3,987,104 bp) was found to be associated with hornless in the studied population. A total of 28 protein-coding genes are mapped in this region, including the taurine Polled locus and the IFNAR1, IFNAR2, IFNGR2, KRTAP11-1, MIS18A, OLIG1, OLIG2, and SOD1 genes, which expression can be related to the horn formation as described in literature. The functional enrichment analysis by DAVID tool revealed cytokine-cytokine receptor interaction, JAK-STAT signaling, natural killer cell mediated cytotoxicity, and osteoclast differentiation pathways as significant (P < 0.05). In addition, a runs of homozygosity (ROH) analysis identified a ROH island in polled animals with 2.47 Mb inside the region identified by WssGWAS. Polledness in Nelore cattle is associated with one region in the genome with 3.1 Mb size in chromosome 1. Several genes are harbored in this region, and they may act together in the determination of the polled/horned phenotype. Fine mapping the locus responsible for polled trait in Nelore breed and the identification of the molecular mechanisms regulating the horn growth deserve further investigation.

Cytokine expression in response to root repair agents

AIM

To evaluate the expression of TNF-α, IL-6, IFN-γ, TGF-β, IL-4, IL-10, RANKL, RANK and OPG on mouse calvarial bone treated with MTA, Geristore^® and Emdogain^® .

METHODOLOGY

Bone wounds were made on the heads of C57BL/6 mice, breaking the periosteum and the cortical surface of the calvaria. Each repair agent was inserted into sectioned Eppendorf microtubes and placed on the bone wound, and soft tissues were sutured. At 14 and 21 days, animals were sacrificed and the treated region was dissected. The calvaria bone was removed, and RNA was extracted. mRNA expression of the aforementioned cytokines was assessed using real-time PCR. Data were analysed by nonparametric methods, including the Mann-Whitney and Kruskal-Wallis tests (P < 0.05).

RESULTS

Following treatment with Emdogain^® and MTA, mRNA expression of RANKL, RANK and OPG increased significantly (P < 0.05) between days 14 to 21. Geristore^® did not alter the basal expression of these mediators during the same period of evaluation. Whilst treatment with Emdogain^® did cause a significant increase in TNF-α mRNA expression between days 14 and 21 (P < 0.05), treatment with MTA did not alter the basal expression of this cytokine at either experimental time point. However, TNF-α mRNA expression was down-regulated significantly at day 21 (P < 0.05) when Geristore^® was applied. A significant increase in the mRNA expression of IL-6, TGF-β, IL-10, IL-4 and IFN-γ was observed with Emdogain^® and MTA treatment between days 14 to 21, whereas Geristore^® reduced significantly the expression of IL-6, TGF-β and IL-4 (P < 0.05).

CONCLUSION

The clinical indication of these repair agents depends on the root resorption diagnosis. Whilst MTA and Emdogain^® induce a pro- and anti-inflammatory response early and late, respectively, Geristore^® was not associated with an inflammatory reaction when compared with both repair agents.

IL-20 bone diseases involvement and therapeutic target potential

BACKGROUND

Millions of people around the world suffer from bone disorders, likes osteoporosis, rheumatoid arthritis (RA), and cancer-induced osteolysis. In general, the bone remodeling balance is determined by osteoclasts and osteoblasts, respectively responsible for bone resorption and bone formation. Excessive inflammation disturbs the activities of these two kinds of cells, typically resulting in the bone loss.

MAIN BODY

IL-20 is emerging as a potent angiogenic, chemotactic, and proinflammatory cytokine related to several chronic inflammatory disorders likes psoriasis, atherosclerosis, cancer, liver fibrosis, and RA. IL-20 has an important role in the regulation of osteoclastogenesis and osteoblastogenesis and is upregulated in several bone-related diseases. The anti-IL-20 monoclonal antibody treatment has a therapeutic potential in several experimental disease models including ovariectomy-induced osteoporosis, cancer-induced osteolysis, and bone fracture.

CONCLUSION

This review article provides an overview describing the IL-20's biological functions in the common bone disorders and thus providing a novel therapeutic strategy in the future.

Regulation of Osteoclast Differentiation by Cytokine Networks

Cytokines play a pivotal role in maintaining bone homeostasis. Osteoclasts (OCs), the sole bone resorbing cells, are regulated by numerous cytokines. Macrophage colony-stimulating factor and receptor activator of NF-κB ligand play a central role in OC differentiation, which is also termed osteoclastogenesis. Osteoclastogenic cytokines, including tumor necrosis factor-α, IL-1, IL-6, IL-7, IL-8, IL-11, IL-15, IL-17, IL-23, and IL-34, promote OC differentiation, whereas anti-osteoclastogenic cytokines, including interferon (IFN)-α, IFN-β, IFN-γ, IL-3, IL-4, IL-10, IL-12, IL-27, and IL-33, downregulate OC differentiation. Therefore, dynamic regulation of osteoclastogenic and anti-osteoclastogenic cytokines is important in maintaining the balance between bone-resorbing OCs and bone-forming osteoblasts (OBs), which eventually affects bone integrity. This review outlines the osteoclastogenic and anti-osteoclastogenic properties of cytokines with regard to osteoimmunology, and summarizes our current understanding of the roles these cytokines play in osteoclastogenesis.

A preliminary investigation of short-term cytokine expression in gingival crevicular fluid secondary to high-level orthodontic forces and the associated root resorption: case series analytical study

BACKGROUND

Orthodontically induced iatrogenic root resorption (OIIRR) is an unavoidable inflammatory process. Several factors claimed to be related to the severity of OIIRR. Orthodontic forces cause micro-trauma to the periodontal ligament and activate a cascade of cellular events associated with local periodontal inflammation. The purpose of this split-mouth study were (1) to investigate the changes in cytokine profile in the gingival crevicular fluid (GCF) secondary to heavy orthodontic forces and (2) to compare the cytokine expression between participants showing high and low root resorption.

METHODS

Eight participants requiring maxillary first premolar extractions involved in this study. The teeth on the tested side (TS) received 225 g of controlled buccal tipping force for 28 days, while the contralateral teeth act as a control (CS). GCF was collected from both TS and CS teeth at 0 h (prior to application of force) and 3 h, 1 day, 3 days, 7 days and 28 days after the application of force, and analysed with multiplex bead immunoassay to determine the cytokine levels.

RESULTS

Statistically significant temporal increase was found in the TS teeth for tumour necrosis factor alpha (TNF-α) at 3 h and 28 days (p = 0.01). Interleukin 7 (IL-7) significantly peaked at the 28th day. Comparing cytokine profile for participants with high and low root resorption (>0.35 and <0.15 mm3, respectively), the levels of GM-CSF was significantly greater in low root resorption cases (p < 0.05). The amounts of root resorption which craters on mesial, distal surfaces and middle third region were significant in the TS teeth (p < 0.05).

CONCLUSIONS

IL-7 and TNF-α (pro-resorptive cytokine) increased significantly secondary to a high-level of orthodontic force application. Significantly high levels of granulocyte macrophage colony-stimulating factor (anti-resorptive cytokine) were detected in mild root resorption cases secondary to high-level orthodontic force application. A future long-term randomised clinical trial with larger sample taking in consideration gender, age and growth pattern distribution would be recommended.

Markers in blood and saliva for prediction of orthodontically induced inflammatory root resorption: a retrospective case controlled-study

BACKGROUND

Hormonal and enzymatic factors may render certain individuals more susceptible to orthodontically induced inflammatory root resorption (OIIRR). The objectives of this study are (1) to identify biochemical key markers in blood and saliva that may be correlated to the trend of extensive OIIRR and (2) to utilise these markers to predict a susceptible patient-receiving orthodontic treatment.

METHODS

Nine patients (mean age 23 + 2.9 years) who had moderate to severe OIIRR that assessed via orthopantomograms and met the inclusion criteria were classified as the root resorption group (RRG). Blood chemistry was evaluated using the collection of fasting blood and unstimulated saliva samples. Multiplex enzyme-linked immunosorbent assay (ELISA) arrays were used to screen blood and saliva samples for human cytokines, chemokines and several key enzymes that may play a role in root resorption following orthodontic force application. Biochemical findings from 16 matching subjects were used as the control (CG) for comparative measurements.

RESULTS

Patients with moderate to severe OIIRR showed a significant increase in salivary cytokines including interleukin (IL) 7, IL-10, IL-12p70 and interferon-gamma (IFN-γ) level as well as a significant decrease in IL-4 level. Osteocalcin and procollagen type I N-terminal peptide (P1NP) appeared to be the only blood factors that showed a significant difference, more in the CG than the RRG.

CONCLUSIONS

Saliva might be a more valuable way of measuring changes in cytokine expression than blood secondary to orthodontic treatment. Although the increased expression of pro-inflammatory and anti-inflammatory cytokines may be determinants in the development of moderate to severe OIIRR, cytokine expression may be affected by several potential inflammations in another part of the body. Future research could investigate the cause/effect relationship of different cytokines, in a larger group of patients and at different time intervals, using digital subtraction radiography techniques and microfluidic biosensors.

Personalized identification of differentially expressed pathways in pediatric sepsis

Sepsis is a leading killer of children worldwide with numerous differentially expressed genes reported to be associated with sepsis. Identifying core pathways in an individual is important for understanding septic mechanisms and for the future application of custom therapeutic decisions. Samples used in the study were from a control group (n=18) and pediatric sepsis group (n=52). Based on Kauffman's attractor theory, differentially expressed pathways associated with pediatric sepsis were detected as attractors. When the distribution results of attractors are consistent with the distribution of total data assessed using support vector machine, the individualized pathway aberrance score (iPAS) was calculated to distinguish differences. Through attractor and Kyoto Encyclopedia of Genes and Genomes functional analysis, 277 enriched pathways were identified as attractors. There were 81 pathways with P<0.05 and 59 pathways with P<0.01. Distribution outcomes of screened attractors were mostly consistent with the total data demonstrated by the six classifying parameters, which suggested the efficiency of attractors. Cluster analysis of pediatric sepsis using the iPAS method identified seven pathway clusters and four sample clusters. Thus, in the majority pediatric sepsis samples, core pathways can be detected as different from accumulated normal samples. In conclusion, a novel procedure that identified the dysregulated attractors in individuals with pediatric sepsis was constructed. Attractors can be markers to identify pathways involved in pediatric sepsis. iPAS may provide a correlation score for each of the signaling pathways present in an individual patient. This process may improve the personalized interpretation of disease mechanisms and may be useful in the forthcoming era of personalized medicine.

Posttranscriptional Interaction Between miR-450a-5p and miR-28-5p and STAT1 mRNA Triggers Osteoblastic Differentiation of Human Mesenchymal Stem Cells

We demonstrate that the interaction between miR-450a-5p and miR-28-5p and signal transducer and activator of transcription 1 (STAT1) mRNA correlates with the osteoblastic differentiation of mesenchymal stem cells from human exfoliated deciduous teeth (shed cells). STAT1 negatively regulates runx-related transcription factor 2 (RUNX2), which is an essential transcription factor in this process. However, the elements that trigger osteoblastic differentiation and therefore pause the inhibitory effect of STAT1 need investigation. Usually, STAT1 can be posttranscriptionally regulated by miRNAs. To test this, we used an in vitro model system in which shed cells were chemically induced toward osteoblastic differentiation and temporally analyzed, comparing undifferentiated cells with their counterparts in the early (2 days) or late (7 or 21 days) periods of induction. The definition of the entire functional genome expression signature demonstrated that the transcriptional activity of a large set of mRNAs and miRNAs changes during this process. Interestingly, STAT1 and RUNX2 mRNAs feature contrasting expression levels during the course of differentiation. While undifferentiated or early differentiating cells express high levels of STAT1 mRNA, which was gradually downregulated, RUNX2 mRNA was upregulated toward differentiation. The reconstruction of miRNA-mRNA interaction networks allowed the identification of six miRNAs (miR-17-3p, miR-28-5p, miR-29b, miR-29c-5p, miR-145-3p, and miR-450a-5p), and we predicted their respective targets, from which we focused on miR-450a-5p and miR-28-5p STAT1 mRNA interactions, whose intracellular occurrence was validated through the luciferase assay. Transfections of undifferentiated shed cells with miR-450a-5p or miR-28-5p mimics or with miR-450a-5p or miR-28-5p antagonists demonstrated that these miRNAs might play a role as posttranscriptional controllers of STAT1 mRNA during osteoblastic differentiation. J. Cell. Biochem. 118: 4045-4062, 2017. © 2017 Wiley Periodicals, Inc.

Abrasive Endoprosthetic Wear Particles Inhibit IFN-γ Secretion in Human Monocytes Via Upregulating TNF-α-Induced miR-29b

The adverse biological responses to prostheses wear particles commonly led to the failure of total hip arthroplasty. Among the released cytokines, interferon-γ (IFN-γ) has been found to be a critical functional factor during osteoclast differentiation. However, the molecular mechanism underlying the regulation of IFN-γ in wear particles-induced cells still needs to be determined. Four kinds of abrasive endoprosthetic wear particle were used to treat THP-1 cells, including polymethylmethacrylate (PMMA), zirconiumoxide (ZrO₂), commercially pure titanium (cpTi), and titanium alloy (Ti-6Al-7Nb), with a concentration of 0.01, 0.05, 0.1, or 0.2 mg/ml for 48 h. The expression of IFN-γ and miR-29b was detected by real-time RT-PCR or ELISA. Luciferase reporter assay was performed to determine the regulation of miR-29b on IFN-γ. The effect of miR-29b inhibitor on the expression of wear particle-induced IFN-γ was detected. The expression of miR-29b was examined in THP-1 cells treated with tumor necrosis factor-alpha (TNF-α). The expression of IFN-γ was downregulated and the level of miR-29b was increased in THP-1 cells pretreated with wear particles. IFN-γ was a target of miR-29b. Wear particles inhibited the expression of IFN-γ through miR-29b. The expression of miR-29b was significantly reduced in THP-1 cells treated with TNF-α neutralizing antibody and particles comparing to that in the cells treated with particles alone. Wear particles inhibit the IFN-γ secretion in human monocytes, which was associated with the upregulating TNF-α-induced miR-29b.

Anti-Osteoporotic Activity of Harpagoside by Upregulation of the BMP2 and Wnt Signaling Pathways in Osteoblasts and Suppression of Differentiation in Osteoclasts

Harpagoside (1) is an iridoid glycoside isolated from the radix of Harpagophytum procumbens var. sublobatum, commonly called Devil's claw. The anti-osteoporotic effect of 1 was investigated in both in vitro cell cultures and in vivo using an ovariectomized (OVX) mouse model. Compound 1 induced bone formation by stimulating osteoblast proliferation, alkaline phosphatase activity, and mineralization in osteoblastic MC3T3-E1 cells. Treatment with 1 increased the mRNA and protein expression of bone formation biomarkers through regulation of the BMP2 and Wnt signaling pathway in MC3T3-E1 cells. Compound 1 also suppressed the RANKL-induced osteoclastogenesis of cultured mouse bone marrow cells. Oral administration of 1 restored the OVX-induced destruction of trabecular bone. The bone mineral density of the femur was also increased significantly by 1. The elevated serum levels of osteocalcin, C-terminal telopeptide, and tartrate-resistant acid phosphatase in the OVX mice were decreased by treatment with 1. These findings suggest that compound 1 may protect against bone loss induced by OVX in mice by regulating stimulation of osteoblast differentiation and inhibition of osteoclast resorption. Therefore, harpagoside (1) is a potential candidate for management of postmenopausal osteoporosis.

Polymorphisms in key bone modulator cytokines genes influence bisphosphonates therapy in postmenopausal women

Osteoporosis is a multifactorial and debilitating disease resulting from decreased bone mineral density (BMD) and loss of tissue microarchitecture. Ineffective therapies may lead to bone fractures and subsequent death. Single nucleotide polymorphisms (SNPs) in key immune regulator genes have been associated with therapeutic response to bisphosphonates, which are the first therapeutic line of choice for osteoporosis. However, cytokine pathways and their relation with therapeutic adhesion remain to be fully elucidated. Aimed at better understanding these processes, we investigated the response to bisphosphonate therapy in postmenopausal women and four SNPs in key proinflammatory cytokines genes: IL23R +2284 (C>A) (rs10889677), IL17A +672 (G>A) (rs7747909), IL12B +1188 (T>G) (rs3212227) and INF-γ -1616 (G>A) (rs2069705). A total of 69 patients treated with bisphosphonate were followed for a period of 1 up to 4 years, genotyped and compared according to their changes in bone mineral density (BMD) and level of biochemical markers during their treatment. The INF-γ -1616 G/G associated with increased BMD values in femoral neck (GG/AA, p = 0.016) and decreased BMD values in total hip (GG/GA, p = 0.019; GG/AA, p = 0.011). In relation to biochemical markers, INF-γ -1616 SNP associated with increased alkaline phosphatase (GG/AA; p < 0.0001) and parathyroid hormone levels (AA/GA; p = 0.017). Vitamin D values changes were related to IL17A +672 (GG/GA, p = 0.034) and to IL12B +1188 (TT/TG, p = 0.046) SNPs. Besides, significant differences in changes of calcium levels correlated with IL23R +2284 (CC/CA, p = 0.016) genotypes. Altogether, we suggest that these polymorphisms may play an important role for therapeutic decisions in osteoporosis treatment.

TiAl6V4 particles promote osteoclast formation via autophagy-mediated downregulation of interferon-beta in osteocytes

Wear debris-induced osteolysis is the leading cause of aseptic loosening, which is the most common reason for total hip arthroplasty (THA) failure in the medium and long term. Although osteocytes are the most abundant cells in bone and make direct contact with implants, the interaction between osteocytes and wear debris remains largely unknown. In the present study, we investigated the effect of TiAl₆V₄ alloy particles (TiPs) on osteocytes and the subsequent effects on osteoclast formation. Our study demonstrated that osteocyte-conditioned medium (CM) inhibited osteoclast differentiation from bone marrow monocytes (BMMs) to osteoclasts. However, TiPs attenuated this inhibitory effect. The expression of several osteoclastogenesis-associated factors, including receptor activator of nuclear factor-kappaB ligand (RANKL), osteoprotegerin (OPG), nitric oxide (NO) and interferon-beta (IFN-β), was examined, and we found that TiPs markedly decreased the expression of IFN-β, but not the other factors. In an osteoclastogenesis assay, our results suggested that the downregulation of IFN-β mediated the stimulatory effect of TiPs on osteoclastogenesis. Additional evidence suggested that TiPs decreased the expression of IFN-β in osteocytes via macroautophagy (hereinafter referred to as "autophagy"). Moreover, inhibiting autophagy with Atg5 siRNA prevented the increase in osteoclastogenesis induced by TiPs. Collectively, these results suggested a possible mechanism underlying wear debris-induced osteolysis.

STATEMENT OF SIGNIFICANCE

For the first time, our study demonstrated that Ti-alloy particles attenuated the inhibitory effect of osteocytes-conditioned medium on osteoclast formation. With an osteoclastogenesis assay, we found that the downregulation of IFN-β in osteocytes mediated the promoting effect of TiPs on osteoclast formation. Furthermore, our results suggested that TiPs-induced autophagy mediated the downregulation of IFN-β in osteocytes. Inhibition of autophagy recovered the expression of IFN-β and ameliorated the promoting effect of TiPs on osteoclast formation. Collectively, these findings suggest a possible mechanism underlying wear debris-induced osteolysis and identified autophagy inhibition in osteocytes as a potential therapeutic approach for wear debris induced osteolysis.

Proinflammatory M1 Macrophages Inhibit RANKL-Induced Osteoclastogenesis

In response to a defined panel of stimuli, immature macrophages can be classified into two major phenotypes: proinflammatory (M1) and anti-inflammatory (M2). Although both phenotypes have been implicated in several chronic inflammatory diseases, their direct role in bone resorption remains unclear. The present study investigated the possible effects of M1 and M2 macrophages on RANKL-induced osteoclastogenesis. In osteoclastogenesis assays using RAW264.7 cells or bone marrow cells as osteoclast precursors, addition of M1 macrophages significantly suppressed RANKL-induced osteoclastogenesis compared to nonstimulated conditions (M0), addition of M2 macrophages, or no macrophage addition (P < 0.05), suggesting that M1 macrophages can downregulate osteoclastogenesis. This effect was maintained when direct contact between M1 and osteoclast precursors was interrupted by cell culture insertion, indicating engagement of soluble factors released from M1. M1 macrophages developed from interferon gamma (IFN-γ) knockout (IFN-γ-KO) mice lost the ability to downregulate osteoclastogenesis. Antibody-based neutralization of interleukin-12 (IL-12), but not IL-10, produced by M1 macrophages also abrogated M1-mediated downregulation of osteoclastogenesis. Real-time PCR analyses showed that IFN-γ suppressed gene expression of NFATc1, a master regulator of osteoclastogenesis, whereas IL-12 increased the apoptosis of osteoclasts, suggesting molecular mechanisms underlying the possible roles of IFN-γ or IL-12 in M1-mediated inhibition of osteoclastogenesis. These findings were confirmed in an in vivo ligature-induced mouse periodontitis model in which adoptive transfer of M1 macrophages showed a significantly lower level of bone loss and less tartrate-resistant acid phosphatase (TRAP)-positive cell induction than M0 or M2 macrophage transfer. In conclusion, by its secretion of IFN-γ and IL-12, M1, but not M0 or M2, was demonstrated to inhibit osteoclastogenesis.

Osteoclast-Primed Foxp3+ CD8 T Cells Induce T-bet, Eomesodermin, and IFN-γ To Regulate Bone Resorption

Osteoimmunology arose from the recognition that cytokines produced by lymphocytes can affect bone homeostasis. We have previously shown that osteoclasts, cells that resorb bone, act as APCs. Cross-presentation of Ags by osteoclasts leads to expression of CD25 and Foxp3, markers of regulatory T cells in the CD8 T cells. Octeoclast-induced Foxp3(+) CD25(+) regulatory CD8 T cells (OC-iTcREG) suppress priming of CD4 and CD8 T cells by dendritic cells. OC-iTcREG also limit bone resorption by osteoclasts, forming a negative feedback loop. In this study, we show that OC-iTcREG express concurrently T-bet and Eomesodermin (Eomes) and IFN-γ. Pharmacological inhibition of IκK blocked IFN-γ, T-bet, and Eomes production by TcREG Furthermore, we show, using chromatin immunoprecipitation, NF-κB enrichment in the T-bet and Eomes promoters. We demonstrate that IFN-γ produced by TcREG is required for suppression of osteoclastogenesis and for degradation of TNFR-associated factor 6 in osteoclast precursors. The latter prevents signaling by receptor activator of NF-κB ligand needed for osteoclastogenesis. Knockout of IFN-γ rendered TcREG inefficient in preventing actin ring formation in osteoclasts, a process required for bone resorption. TcREG generated in vivo using IFN-γ(-/-) T cells had impaired ability to protect mice from bone resorption and bone loss in response to high-dose receptor activator of NF-κB ligand. The results of this study demonstrate a novel link between NF-κB signaling and induction of IFN-γ in TcREG and establish an important role for IFN-γ in TcREG-mediated protection from bone loss.

Effects of Pegylated Interferon/Ribavirin on Bone Turnover Markers in HIV/Hepatitis C Virus-Coinfected Patients

HIV/hepatitis C virus (HCV) patients have a 3-fold increased fracture incidence compared to uninfected patients. The impact of HCV therapy on bone health is unclear. We evaluated bone turnover markers (BTM) in well-controlled (HIV RNA <50 copies/ml) HIV/HCV-coinfected patients who received pegylated interferon-α and ribavirin (PEG-IFN/RBV) in ACTG trial A5178. Early virologic responders (EVR: ≥2 log HCV RNA drop at week 12) continued PEG-IFN/RBV and non-EVRs were randomized to continuation of PEG-IFN alone or observation. We assessed changes in C-terminal telopeptide of type 1 collagen (CTX; bone resorption marker) and procollagen type I intact N-terminal propeptide (P1NP; bone formation marker), and whether BTM changes were associated with EVR, complete early virologic response (cEVR: HCV RNA <600 IU/ml at week 12), or PEG-IFN treatment. A total of 192 subjects were included. After 12 weeks of PEG-IFN/RBV, CTX and P1NP decreased: −120 pg/ml and −8.48 μg/liter, respectively (both p < 0.0001). CTX declines were greater in cEVR (N = 91; vs. non-cEVR (N = 101; p = 0.003). From week 12 to 24, CTX declines were sustained among EVR patients who continued PEG-IFN/RBV (p = 0.027 vs. non-EVR) and among non-EVR patients who continued PEG-IFN alone (p = 0.022 vs. Observation). Median decreases of P1NP in EVR vs. non-EVR were similar at weeks 12 and 24. PEG-IFN-based therapy for chronic HCV markedly reduces bone turnover. It is unclear whether this is a direct IFN effect or a result of HCV viral clearance, or whether they will result in improved bone mineral density. Further studies with IFN-free regimens should explore these questions.

Elevated Response to Type I IFN Enhances RANKL-Mediated Osteoclastogenesis in Usp18-Knockout Mice

A balance between bone formation and bone resorption is critical for the maintenance of bone mass. In many pathological conditions, including chronic inflammation, uncontrolled activation of osteoclast differentiation often causes excessive bone resorption that results in osteoporosis. In this study, we identified the osteopenia phenotype of mice lacking Usp18 (also called Ubp43), which is a deISGylating enzyme and is known as a negative regulator of type I IFN signaling. The expression of Usp18 was induced in preosteoclasts upon receptor activator of NF-κB ligand (RANKL) treatment. In an in vitro osteoclast-differentiation assay, bone marrow macrophages from Usp18-deficient mice exhibited an enhanced differentiation to multinucleated cells, elevated activation of NFATc1, and an increased expression of osteoclast marker genes upon RANKL treatment. Furthermore, in vitro quantification of bone resorption revealed a great increase in osteoclastic activities in Usp18-deficient cells. Interestingly, proinflammatory cytokine genes, such as IP-10 (CXCL10), were highly expressed in Usp18-deficient bone marrow macrophages upon RANKL treatment compared with wild-type cells. In addition, serum cytokine levels, especially IP-10, were significantly high in Usp18-knockout mice. In sum, we suggest that, although type I IFN is known to restrict osteoclast differentiation, the exaggerated activation of the type I IFN response in Usp18-knockout mice causes an osteopenia phenotype in mice.

The roles of interferons in osteoclasts and osteoclastogenesis

Interferons (IFNs) play essential roles in regulating osteoclast differentiation and bone resorption. Over the last decade, we have seen tremendous developments in our understanding of the mechanisms by which interferons regulate osteoclastogenesis. Of the type I interferons, IFN-β inhibits osteoclastogenesis via autoregulatory or exogenous regulatory mechanisms, while IFN-α was recently shown to participate in regulating osteoclast formation. And the only member of type II interferons, IFN-γ, has biphasic effects on osteoclastogenesis. Type III interferons have also been shown to be involved in osteoclast bone resorption, although no direct regulatory mechanism has been demonstrated. In this review, we provide an update account of the current knowledge on these recently revealed novel roles of interferons in the regulation of a variety of signaling pathways in osteoclast differentiation and function. The potential clinical applications are also discussed.