Aims. Osteoarthritis (OA) is a prevalent joint disorder with inflammatory response and cartilage deterioration as its main features. Dihydrocaffeic acid (DHCA), a bioactive component extracted from natural plant (gynura bicolor), has demonstrated anti-inflammatory properties in various diseases. We aimed to explore the chondroprotective effect of DHCA on OA and its potential mechanism. Methods. In vitro, interleukin-1 beta (IL-1β) was used to establish the mice OA chondrocytes. Cell counting kit-8 evaluated chondrocyte viability. Western blotting analyzed the expression levels of collagen II, aggrecan, SOX9, inducible nitric oxide synthase (iNOS), IL-6, matrix metalloproteinases (MMPs: MMP1, MMP3, and MMP13), and signalling molecules associated with nuclear factor-kappa B (NF-κB) and mitogen-activated protein kinase (MAPK) pathways. Immunofluorescence analysis assessed the expression of aggrecan, collagen II, MMP13, and p-P65. In vivo, a destabilized medial meniscus (DMM) surgery was used to induce mice OA knee joints. After injection of DHCA or a vehicle into the injured joints, histological staining gauged the severity of cartilage damage. Results. DHCA prevented iNOS and IL-6 from being upregulated by IL-1β. Moreover, the IL-1β-induced upregulation of MMPs could be inhibited by DHCA. Additionally, the administration of DHCA counteracted IL-1β-induced downregulation of aggrecan, collagen II, and SOX9. DHCA protected articular cartilage by blocking the NF-κB and MAPK pathways. Furthermore, DHCA mitigated the destruction of articular cartilage in vivo. Conclusion. We present evidence that DHCA alleviates inflammation and cartilage degradation in OA chondrocytes via suppressing the NF-κB and MAPK pathways, indicating that DHCA may be a potential agent for OA treatment. Cite this article: Bone Joint Res 2023;12(4):259–273

Aims

Interleukin (IL)-1β is one of the major pathogenic regulators during the pathological development of intervertebral disc degeneration (IDD). However, effective treatment options for IDD are limited. Suramin is used to treat African sleeping sickness. This study aimed to investigate the pharmacological effects of suramin on mitigating IDD and to characterize the underlying mechanism.

Aims. Transcription factor nuclear factor kappa B (NF-κB) plays a major role in the pathogenesis of chronic inflammatory diseases in all organ systems. Despite its importance, NF-κB targeted drug therapy to mitigate chronic inflammation has had limited success in preclinical studies. We hypothesized that sex differences affect the response to NF-κB treatment during chronic inflammation in bone. This study investigated the therapeutic effects of NF-κB decoy oligodeoxynucleotides (ODN) during chronic inflammation in male and female mice. Methods. We used a murine model of chronic inflammation induced by continuous intramedullary delivery of lipopolysaccharide-contaminated polyethylene particles (cPE) using an osmotic pump. Specimens were evaluated using micro-CT and histomorphometric analyses. Sex-specific osteogenic and osteoclastic differentiation potentials were also investigated in vitro, including alkaline phosphatase, Alizarin Red, tartrate-resistant acid phosphatase staining, and gene expression using reverse transcription polymerase chain reaction (RT-PCR). Results. Local delivery of NF-κB decoy ODN in vivo increased osteogenesis in males, but not females, in the presence of chronic inflammation induced by cPE. Bone resorption activity was decreased in both sexes. In vitro osteogenic and osteoclastic differentiation assays during inflammatory conditions did not reveal differences among the groups. Receptor activator of nuclear factor kappa Β ligand (Rankl) gene expression by osteoblasts was significantly decreased only in males when treated with ODN. Conclusion. We demonstrated that NF-κB decoy ODN increased osteogenesis in male mice and decreased bone resorption activity in both sexes in preclinical models of chronic inflammation. NF-κB signalling could be a therapeutic target for chronic inflammatory diseases involving bone, especially in males. Cite this article: Bone Joint Res 2024;13(1):28–39

Aims. The role of N,N-dimethylformamide (DMF) in diabetes-induced osteoporosis (DM-OS) progression remains unclear. Here, we aimed to explore the effect of DMF on DM-OS development. Methods. Diabetic models of mice, RAW 264.7 cells, and bone marrow macrophages (BMMs) were established by streptozotocin stimulation, high glucose treatment, and receptor activator of nuclear factor-κB ligand (RANKL) treatment, respectively. The effects of DMF on DM-OS development in these models were examined by micro-CT analysis, haematoxylin and eosin (H&E) staining, osteoclast differentiation of RAW 264.7 cells and BMMs, H&E and tartrate-resistant acid phosphatase (TRAP) staining, enzyme-linked immunosorbent assay (ELISA) of TRAP5b and c-terminal telopeptides of type 1 (CTX1) analyses, reactive oxygen species (ROS) analysis, quantitative reverse transcription polymerase chain reaction (qRT-PCR), Cell Counting Kit-8 (CCK-8) assay, and Western blot. Results. The established diabetic mice were more sensitive to ovariectomy (OVX)-induced osteoporosis, and DMF treatment inhibited the sensitivity. OVX-treated diabetic mice exhibited higher TRAP5b and c-terminal telopeptides of type 1 (CTX1) levels, and DMF treatment inhibited the enhancement. DMF reduced RAW 264.7 cell viability. Glucose treatment enhanced the levels of TRAP5b, cathepsin K, Atp6v0d2, and H. +. -ATPase, ROS, while DMF reversed this phenotype. The glucose-increased protein levels were inhibited by DMF in cells treated with RANKL. The expression levels of antioxidant enzymes Gclc, Gclm, Ho-1, and Nqo1 were upregulated by DMF. DMF attenuated high glucose-caused osteoclast differentiation by targeting mitogen-activated protein kinase (MAPK) and nuclear factor kappa B (NF-κB) signalling in BMMs. Conclusion. DMF inhibits high glucose-induced osteoporosis by targeting MAPK and NF-κB signalling. Cite this article: Bone Joint Res 2022;11(4):200–209

Objectives. This study aimed to explore the role of miR-320a in the pathogenesis of osteoarthritis (OA). Methods. Human cartilage cells (C28/I2) were transfected with miR-320a or antisense oligonucleotides (ASO)-miR-320a, and treated with IL-1β. Subsequently the expression of collagen type II alpha 1 (Col2α1) and aggrecan (ACAN), and the concentrations of sulfated glycosaminoglycans (sGAG) and matrix metallopeptidase 13 (MMP-13), were assessed. Luciferase reporter assay, qRT-PCR, and Western blot were performed to explore whether pre-B-cell leukemia Homeobox 3 (PBX3) was a target of miR-320a. Furthermore, cells were co-transfected with miR-320a and PBX3 expressing vector, or cells were transfected with miR-320a and treated with a nuclear factor kappa B (NF-κB) antagonist MG132. The changes in Col2α1 and ACAN expression, and in sGAG and MMP-13 concentrations, were measured again. Statistical comparisons were made between two groups by using the two-tailed paired t-test. Results. Expression of miR-320a was elevated in OA cartilage tissues and chondrocytes, and in IL-1β-stimulated C28/I2 cells (p < 0.05 or p < 0.01). MiR-320a overexpression enhanced IL-1β-induced down-regulation of Col2α1 and ACAN and sGAG, and increased the IL-1β-induced overexpression of MMP-13 (p < 0.01). PBX3 was a direct target of miR-320a. PBX3 and MG132 co-transfection attenuated the effects of miR-320a on the expression of Col2α1, ACAN, sGAG and MMP-13(p < 0.01). Conclusion. Overexpression of miR-320a might enhance IL-1β-induced cartilage degradation factors. These effects might be via targeting PBX3 and regulating NF-κB. Cite this article: Y. Jin, X. Chen, Z. Y. Gao, K. Liu, Y. Hou, J. Zheng. The role of miR-320a and IL-1β in human chondrocyte degradation. Bone Joint Res 2017;6:–203. DOI: 10.1302/2046-3758.64.BJR-2016-0224.R1

Aims. Rheumatoid arthritis (RA), which mainly results from fibroblast-like synoviocyte (FLS) dysfunction, is related to oxidative stress. Advanced oxidation protein products (AOPPs), which are proinflammatory mediators and a novel biomarker of oxidative stress, have been observed to accumulate significantly in the serum of RA patients. Here, we present the first investigation of the effects of AOPPs on RA-FLSs and the signalling pathway involved in AOPP-induced inflammatory responses and invasive behaviour. Methods. We used different concentrations of AOPPs (50 to 200 µg/ml) to treat RA-FLSs. Cell migration and invasion and the expression levels of tumour necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), matrix metalloproteinase-3 (MMP-3), and MMP-13 were investigated. Western blot and immunofluorescence were used to analyze nuclear factor-κB (NF-κB) activation. Results. AOPPs promoted RA-FLS migration and invasion in vitro and significantly induced the messenger RNA (mRNA) and protein expression of TNF-α, IL-6, MMP-3, and MMP-13 in dose- and time-dependent manners. Moreover, AOPPs markedly activated the phosphorylation of nuclear factor-κB (NF-κB) p65 protein, which triggered inhibitory kappa B-alpha (IκBα) degradation, NF-κB p65 protein phosphorylation, and NF-κB p65 translocation into the nucleus. Furthermore, treatment with a neutralizing antibody specific to receptor for advanced glycation end products (RAGE) significantly suppressed aggressive behaviour and inflammation, decreased TNF-α, IL-6, MMP-3, and MMP-13 expression, and blocked AOPP-induced NF-κB pathway activation. Conclusion. The results indicate that AOPPs can enhance aggressive behaviour and the inflammatory response in RA-FLSs via the RAGE–NF-κB pathway. These results present AOPPs as a new class of potentially important mediators of progressive disease in RA patients. Cite this article: Bone Joint Res 2021;10(4):259–268

Aims. Receptor activator of nuclear factor-κB ligand (RANKL) is a key molecule that is expressed in bone stromal cells and is associated with metastasis and poor prognosis in many cancers. However, cancer cells that directly express RANKL have yet to be unveiled. The current study sought to evaluate how a single subunit of G protein, guanine nucleotide-binding protein G(q) subunit alpha (GNAQ), transforms cancer cells into RANKL-expressing cancer cells. Methods. We investigated the specific role of GNAQ using GNAQ wild-type cell lines (non-small-cell lung cancer cell lines; A549 cell lines), GNAQ knockdown cell lines, and patient-derived cancer cells. We evaluated GNAQ, RANKL, macrophage colony-stimulating factor (M-CSF), nuclear transcription factor-κB (NF-κB), inhibitor of NF-κB (IκB), and protein kinase B (Akt) signalling in the GNAQ wild-type and the GNAQ-knockdown cells. Osteoclastogenesis was also evaluated in both cell lines. Results. In the GNAQ-knockdown cells, RANKL expression was significantly upregulated (p < 0.001). The expression levels of M-CSF were also significantly increased in the GNAQ-knockdown cells compared with control cells (p < 0.001). GNAQ knockdown cells were highly sensitive to tumour necrosis factor alpha (TNF-α) and showed significant activation of the NF-κB pathway. The expression levels of RANKL were markedly increased in GNAQ mutant compared with GNAQ wild-type in patient-derived tumour tissues. Conclusion. The present study reveals that the alterations of GNAQ activate NF-κB pathway in cancers, which increase RANKL and M-CSF expression and induce osteoclastogenesis in cancers. Cite this article:Bone Joint Res. 2020;9(1):29–35

Objectives. Ubiquitin E3 ligase-mediated protein degradation regulates osteoblast function. Itch, an E3 ligase, affects numerous cell functions by regulating ubiquitination and proteasomal degradation of related proteins. However, the Itch-related cellular and molecular mechanisms by which osteoblast differentiation and function are elevated during bone fracture repair are as yet unknown. Methods. We examined the expression levels of E3 ligases and NF-κB members in callus samples during bone fracture repair by quantitative polymerase chain reaction (qPCR) and the total amount of ubiquitinated proteins by Western blot analysis in wild-type (WT) mice. The expression levels of osteoblast-associated genes in fracture callus from Itch knockout (KO) mice and their WT littermates were examined by qPCR. The effect of NF-κB on Itch expression in C2C12 osteoblast cells was determined by a chromatin immunoprecipitation (ChIP) assay. Results. The expression levels of WW Domain Containing E3 Ubiquitin Protein Ligase 1 (Wwp1), SMAD Specific E3 Ubiquitin Protein Ligase 1 (Smurf1), SMAD Specific E3 Ubiquitin Protein Ligase 2 (Smurf2) and Itch were all significantly increased in the fracture callus of WT mice, which was associated with elevated expression of NF-κB members and total ubiquitinated proteins. Callus tissue isolated from Itch KO mice expressed higher levels of osteoblast-associated genes, including Runx2, a positive regulator of osteoblast differentiation, but osteoclast-associated genes were not increased. Both NF-κB RelA and RelB proteins were found to bind to the NF-κB binding site in the mouse Itch promoter. Conclusions. Our findings indicate that Itch depletion may have a strong positive effect on osteoblast differentiation in fracture callus. Thus, ubiquitin E3 ligase Itch could be a potential target for enhancing bone fracture healing. Cite this article: J. Liu, X. Li, H. Zhang, R. Gu, Z. Wang, Z. Gao, L. Xing. Ubiquitin E3 ligase Itch negatively regulates osteoblast function by promoting proteasome degradation of osteogenic proteins. Bone Joint Res 2017;6:154–161. DOI: 10.1302/2046-3758.63.BJR-2016-0237.R1

Aims. Pellino1 (Peli1) has been reported to regulate various inflammatory diseases. This study aims to explore the role of Peli1 in the occurrence and development of osteoarthritis (OA), so as to find new targets for the treatment of OA. Methods. After inhibiting Peli1 expression in chondrocytes with small interfering RNA (siRNA), interleukin (IL)-1β was used to simulate inflammation, and OA-related indicators such as synthesis, decomposition, inflammation, and apoptosis were detected. Toll-like receptor (TLR) and nuclear factor-kappa B (NF-κB) signalling pathway were detected. After inhibiting the expression of Peli1 in macrophages Raw 264.7 with siRNA and intervening with lipopolysaccharide (LPS), the polarization index of macrophages was detected, and the supernatant of macrophage medium was extracted as conditioned medium to act on chondrocytes and detect the apoptosis index. The OA model of mice was established by destabilized medial meniscus (DMM) surgery, and adenovirus was injected into the knee cavity to reduce the expression of Peli1. The degree of cartilage destruction and synovitis were evaluated by haematoxylin and eosin (H&E) staining, Safranin O/Fast Green staining, and immunohistochemistry. Results. In chondrocytes, knockdown of Peli1 produced anti-inflammatory and anti-apoptotic effects by targeting the TLR and NF-κB signalling pathways. We found that in macrophages, knockdown of Peli1 can inhibit M1-type polarization of macrophages. In addition, the corresponding conditioned culture medium of macrophages applied to chondrocytes can also produce an anti-apoptotic effect. During in vivo experiments, the results have also shown that knockdown Peli1 reduces cartilage destruction and synovial inflammation. Conclusion. Knockdown of Peli1 has a therapeutic effect on OA, which therefore makes it a potential therapeutic target for OA. Cite this article: Bone Joint Res 2023;12(2):121–132

Aims. Inflammatory response plays a pivotal role in the pathophysiological process of intervertebral disc degeneration (IDD). A20 (also known as tumour necrosis factor alpha-induced protein 3 (TNFAIP3)) is a ubiquitin-editing enzyme that restricts nuclear factor-kappa B (NF-κB) signalling. A20 prevents the occurrence of multiple inflammatory diseases. However, the role of A20 in the initiation of IDD has not been elucidated. The aim of the study was to investigate the effect of A20 in senescence of TNF alpha (TNF-α)-induced nucleus pulposus cells (NPCs). Methods. Immunohistochemical staining was performed to observe the expression of A20 in normal and degenerated human intervertebral discs. The NPCs were dissected from the tail vertebrae of healthy male Sprague-Dawley rats and were cultured in the incubator. In the experiment, TNF-α was used to mimic the inflammatory environment of IDD. The cell viability and senescence were examined to investigate the effect of A20 on TNF-α-treated NPCs. The expression of messenger RNA (mRNA)-encoding proteins related to matrix macromolecules (collagen II, aggrecan) and senescence markers (p53, p16). Additionally, NF-κB/p65 activity of NPCs was detected within different test compounds. Results. The expression of A20 was upregulated in degenerate human intervertebral discs. The A20 levels of NPCs in TNF-α inflammatory microenvironments were dramatically higher than those of the control group. TNF-α significantly decreased cell proliferation potency but increased senescence-associated beta-galactosidase (SA-β-Gal) activity, the expression of senescence-associated proteins, the synthesis of extracellular matrix, and G1 cycle arrest. The senescence indicators and NF-κB/p65 expression of A20 downregulated group treated with TNF-α were significantly upregulated compared to TNF-α-treated normal NPCs. Conclusion. A20 has a self-protective effect on the senescence of NPCs induced by TNF-α. The downregulation of A20 in NPCs exacerbated the senescence of NPCs induced by TNF-α. Cite this article:Bone Joint Res. 2020;9(5):225–235

Aims. Tert-butylhydroquinone (tBHQ) has been identified as an inhibitor of oxidative stress-induced injury and apoptosis in human neural stem cells. However, the role of tBHQ in osteoarthritis (OA) is unclear. This study was carried out to investigate the role of tBHQ in OA. Methods. OA animal model was induced by destabilization of the medial meniscus (DMM). Different concentrations of tBHQ (25 and 50 mg/kg) were intraperitoneally injected in ten-week-old female mice. Chondrocytes were isolated from articular cartilage of mice and treated with 5 ng/ml lipopolysaccharide (LPS) or 10 ng/ml interleukin 1 beta (IL-1β) for 24 hours, and then treated with different concentrations of tBHQ (10, 20, and 40 μM) for 12 hours. The expression levels of malondialdehyde (MDA) and superoxide dismutase (SOD) in blood were measured. The expression levels of interleukin 6 (IL-6), IL-1β, and tumour necrosis factor alpha (TNF-α) leptin in plasma were measured using enzyme-linked immunoabsorbent assay (ELISA) kits. The expression of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and mitogen-activated protein kinase (MAPK) signalling pathway proteins, and macrophage repolarization-related markers, were detected by western blot. Results. Tert-butylhydroquinone significantly attenuated cartilage destruction in DMM-induced mice in vivo. It demonstrated clear evidence of inhibiting IL-1β-induced chondrocyte apoptosis, inflammation, and differentiation defect in vitro. Meanwhile, tBHQ inhibited LPS-induced activation of NF-κB and MAPK signalling pathways, and also inhibited LPS-induced reactive oxygen species production and macrophages repolarization in vitro. Conclusion. Taken together, tBHQ might be a potential therapeutic strategy for protecting against OA development. Cite this article: Bone Joint Res 2021;10(11):704–713

Objectives. Enhanced micromotions between the implant and surrounding bone can impair osseointegration, resulting in fibrous encapsulation and aseptic loosening of the implant. Since the effect of micromotions on human bone cells is sparsely investigated, an in vitro system, which allows application of micromotions on bone cells and subsequent investigation of bone cell activity, was developed. Methods. Micromotions ranging from 25 µm to 100 µm were applied as sine or triangle signal with 1 Hz frequency to human osteoblasts seeded on collagen scaffolds. Micromotions were applied for six hours per day over three days. During the micromotions, a static pressure of 527 Pa was exerted on the cells by Ti6Al4V cylinders. Osteoblasts loaded with Ti6Al4V cylinders and unloaded osteoblasts without micromotions served as controls. Subsequently, cell viability, expression of the osteogenic markers collagen type I, alkaline phosphatase, and osteocalcin, as well as gene expression of osteoprotegerin, receptor activator of NF-κB ligand, matrix metalloproteinase-1, and tissue inhibitor of metalloproteinase-1, were investigated. Results. Live and dead cell numbers were higher after 25 µm sine and 50 µm triangle micromotions compared with loaded controls. Collagen type I synthesis was downregulated in respective samples. The metabolic activity and osteocalcin expression level were higher in samples treated with 25 µm micromotions compared with the loaded controls. Furthermore, static loading and micromotions decreased the osteoprotegerin/receptor activator of NF-κB ligand ratio. Conclusion. Our system enables investigation of the behaviour of bone cells at the bone-implant interface under shear stress induced by micromotions. We could demonstrate that micromotions applied under static pressure conditions have a significant impact on the activity of osteoblasts seeded on collagen scaffolds. In future studies, higher mechanical stress will be applied and different implant surface structures will be considered. Cite this article: J. Ziebart, S. Fan, C. Schulze, P. W. Kämmerer, R. Bader, A. Jonitz-Heincke. Effects of interfacial micromotions on vitality and differentiation of human osteoblasts. Bone Joint Res 2018;7:187–195. DOI: 10.1302/2046-3758.72.BJR-2017-0228.R1

Objectives. This study aimed to examine the effects of SRT1720, a potent SIRT1 activator, on osteoarthritis (OA) progression using an experimental OA model. Methods. Osteoarthritis was surgically induced by destabilization of the medial meniscus in eight-week-old C57BL/6 male mice. SRT1720 was administered intraperitoneally twice a week after surgery. Osteoarthritis progression was evaluated histologically using the Osteoarthritis Research Society International (OARSI) score at four, eight, 12 and 16 weeks. The expression of SIRT1, matrix metalloproteinase 13 (MMP-13), a disintegrin and metalloproteinase with thrombospondin motifs-5 (ADAMTS-5), cleaved caspase-3, PARP p85, and acetylated nuclear factor (NF)-κB p65 in cartilage was examined by immunohistochemistry. Synovitis was also evaluated histologically. Primary mouse epiphyseal chondrocytes were treated with SRT1720 in the presence or absence of interleukin 1 beta (IL-1β), and gene expression changes were examined by real-time polymerase chain reaction (PCR). Results. The OARSI score was significantly lower in mice treated with SRT1720 than in control mice at eight and 12 weeks associated with the decreased size of osteophytes at four and eight weeks. The delayed OA progression in the mice treated with SRT1720 was also associated with increased SIRT1-positive chondrocytes and decreased MMP-13-, ADAMTS-5-, cleaved caspase-3-, PARP p85-, and acetylated NF-κB p65-positive chondrocytes and decreased synovitis at four and eight weeks. SRT1720 treatment partially rescued the decreases in collagen type II alpha 1 (COL2A1) and aggrecan caused by IL-1β, while also reducing the induction of MMP-13 by IL-1β in vitro. Conclusion. The intraperitoneal injection of SRT1720 attenuated experimental OA progression in mice, indicating that SRT1720 could be a new therapeutic approach for OA. Cite this article: K. Nishida, T. Matsushita, K. Takayama, T. Tanaka, N. Miyaji, K. Ibaraki, D. Araki, N. Kanzaki, T. Matsumoto, R. Kuroda. Intraperitoneal injection of the SIRT1 activator SRT1720 attenuates the progression of experimental osteoarthritis in mice. Bone Joint Res 2018;7:252–262. DOI: 10.1302/2046-3758.73.BJR-2017-0227.R1

Osteoarthritis (OA) is a degenerative disease resulting from progressive joint destruction caused by many factors. Its pathogenesis is complex and has not been elucidated to date. Advanced glycation end products (AGEs) are a series of irreversible and stable macromolecular complexes formed by reducing sugar with protein, lipid, and nucleic acid through a non-enzymatic glycosylation reaction (Maillard reaction). They are an important indicator of the degree of ageing. Currently, it is considered that AGEs accumulation in vivo is a molecular basis of age-induced OA, and AGEs production and accumulation in vivo is one of the important reasons for the induction and acceleration of the pathological changes of OA. In recent years, it has been found that AGEs are involved in a variety of pathological processes of OA, including extracellular matrix degradation, chondrocyte apoptosis, and autophagy. Clearly, AGEs play an important role in regulating the expression of OA-related genes and maintaining the chondrocyte phenotype and the stability of the intra-articular environment. This article reviews the latest research results of AGEs in a variety of pathological processes of OA, to provide a new direction for the study of OA pathogenesis and a new target for prevention and treatment.

Cite this article: Bone Joint Res 2022;11(5):292–300.

Aims

Impaired fracture repair in patients with type 2 diabetes mellitus (T2DM) is not fully understood. In this study, we aimed to characterize the local changes in gene expression (GE) associated with diabetic fracture. We used an unbiased approach to compare GE in the fracture callus of Zucker diabetic fatty (ZDF) rats relative to wild-type (WT) littermates at three weeks following femoral osteotomy.

Aims

Osteoporosis is characterized by decreased trabecular bone volume, and microarchitectural deterioration in the medullary cavity. Interleukin-19 (IL-19), a member of the IL-10 family, is an anti-inflammatory cytokine produced primarily by macrophages. The aim of our study was to investigate the effect of IL-19 on osteoporosis.

Bone regeneration and repair are crucial to ambulation and quality of life. Factors such as poor general health, serious medical comorbidities, chronic inflammation, and ageing can lead to delayed healing and nonunion of fractures, and persistent bone defects. Bioengineering strategies to heal bone often involve grafting of autologous bone marrow aspirate concentrate (BMAC) or mesenchymal stem cells (MSCs) with biocompatible scaffolds. While BMAC shows promise, variability in its efficacy exists due to discrepancies in MSC concentration and robustness, and immune cell composition. Understanding the mechanisms by which macrophages and lymphocytes – the main cellular components in BMAC – interact with MSCs could suggest novel strategies to enhance bone healing. Macrophages are polarized into pro-inflammatory (M1) or anti-inflammatory (M2) phenotypes, and influence cell metabolism and tissue regeneration via the secretion of cytokines and other factors. T cells, especially helper T1 (Th1) and Th17, promote inflammation and osteoclastogenesis, whereas Th2 and regulatory T (Treg) cells have anti-inflammatory pro-reconstructive effects, thereby supporting osteogenesis. Crosstalk among macrophages, T cells, and MSCs affects the bone microenvironment and regulates the local immune response. Manipulating the proportion and interactions of these cells presents an opportunity to alter the local regenerative capacity of bone, which potentially could enhance clinical outcomes.

Cite this article: Bone Joint Res 2024;13(9):462–473.

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This study aimed to explore the biological and clinical importance of dysregulated key genes in osteoarthritis (OA) patients at the cartilage level to find potential biomarkers and targets for diagnosing and treating OA.

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Biofilm-related infection is a major complication that occurs in orthopaedic surgery. Various treatments are available but efficacy to eradicate infections varies significantly. A systematic review was performed to evaluate therapeutic interventions combating biofilm-related infections on in vivo animal models.

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Degenerative cervical spondylosis (DCS) is a common musculoskeletal disease that encompasses a wide range of progressive degenerative changes and affects all components of the cervical spine. DCS imposes very large social and economic burdens. However, its genetic basis remains elusive.

Aims

Rheumatoid arthritis (RA) is a common chronic immune disease. Berberine, as its main active ingredient, was also contained in a variety of medicinal plants such as Berberaceae, Buttercup, and Rutaceae, which are widely used in digestive system diseases in traditional Chinese medicine with anti-inflammatory and antibacterial effects. The aims of this article were to explore the therapeutic effect and mechanism of berberine on rheumatoid arthritis.

Aims

This study examined the relationship between obesity (OB) and osteoporosis (OP), aiming to identify shared genetic markers and molecular mechanisms to facilitate the development of therapies that target both conditions simultaneously.

Rheumatoid arthritis (RA) is an autoimmune disease characterized by symmetrical and chronic polyarthritis. Fibroblast-like synoviocytes are mainly involved in joint inflammation and cartilage and bone destruction by inflammatory cytokines and matrix-degrading enzymes in RA. Approaches that induce various cellular growth alterations of synoviocytes are considered as potential strategies for treating RA. However, since synoviocytes play a critical role in RA, the mechanism and hyperplastic modulation of synoviocytes and their motility need to be addressed. In this review, we focus on the alteration of synoviocyte signalling and cell fate provided by signalling proteins, various antioxidant molecules, enzymes, compounds, clinical candidates, to understand the pathology of the synoviocytes, and finally to achieve developed therapeutic strategies of RA.

Cite this article: Bone Joint Res 2021;10(4):285–297.

In the differentiation of osteoclasts the differentiation factor (RANKL) interacts with the receptor activator of NF-κB (RANK) in a direct cell-to-cell contact between osteoblast and (pre)osteoclast. This is inhibited by soluble osteoprotegerin (OPG). The mRNA levels of both RANKL (p < 0.01) and RANK (p < 0.05) were high in peri-implant tissue and RANKL+ and RANK+ cells were found in such tissue. Double labelling also disclosed soluble RANKL bound to RANK+ cells. We were unable to stimulate fibroblasts to express RANKL in vitro, but monocyte activation with LPS gave a fivefold increase in RANK mRNA levels. In contrast to RANKL and RANK expression in peri-implant tissue, expression of OPG was restricted to vascular endothelium. Endothelial cell OPG mRNA levels were regulated by TNF-α and VEGF, but not by hypoxia. It is concluded that activated cells in the interface tissue overproduce both RANKL and RANK and they can interact without interference by OPG

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Bone regeneration during treatment of staphylococcal bone infection is challenging due to the ability of Staphylococcus aureus to invade and persist within osteoblasts. Here, we sought to determine whether the metabolic and extracellular organic matrix formation and mineralization ability of S. aureus-infected human osteoblasts can be restored after rifampicin (RMP) therapy.

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Bone metastasis ultimately occurs due to a complex multistep process, during which the interactions between cancer cells and bone microenvironment play important roles. Prior to colonization of the bone, cancer cells must succeed through a series of steps that will allow them to gain migratory and invasive properties; epithelial-to-mesenchymal transition (EMT) is known to be integral here. The aim of this study was to determine the effects of G protein subunit alpha Q (GNAQ) on the mechanisms underlying bone metastasis through EMT pathway.

Osteoarthritis (OA), one of the most common motor system disorders, is a degenerative disease involving progressive joint destruction caused by a variety of factors. At present, OA has become the fourth most common cause of disability in the world. However, the pathogenesis of OA is complex and has not yet been clarified. Long non-coding RNA (lncRNA) refers to a group of RNAs more than 200 nucleotides in length with limited protein-coding potential, which have a wide range of biological functions including regulating transcriptional patterns and protein activity, as well as binding to form endogenous small interference RNAs (siRNAs) and natural microRNA (miRNA) molecular sponges. In recent years, a large number of lncRNAs have been found to be differentially expressed in a variety of pathological processes of OA, including extracellular matrix (ECM) degradation, synovial inflammation, chondrocyte apoptosis, and angiogenesis. Obviously, lncRNAs play important roles in regulating gene expression, maintaining the phenotype of cartilage and synovial cells, and the stability of the intra-articular environment. This article reviews the results of the latest research into the role of lncRNAs in a variety of pathological processes of OA, in order to provide a new direction for the study of OA pathogenesis and a new target for prevention and treatment.

Cite this article: Bone Joint Res 2021;10(2):122–133.

Osteoporosis (OP) is a chronic metabolic bone disease characterized by the decrease of bone tissue per unit volume under the combined action of genetic and environmental factors, which leads to the decrease of bone strength, makes the bone brittle, and raises the possibility of bone fracture. However, the exact mechanism that determines the progression of OP remains to be underlined. There are hundreds of trillions of symbiotic bacteria living in the human gut, which have a mutually beneficial symbiotic relationship with the human body that helps to maintain human health. With the development of modern high-throughput sequencing (HTS) platforms, there has been growing evidence that the gut microbiome may play an important role in the programming of bone metabolism. In the present review, we discuss the potential mechanisms of the gut microbiome in the development of OP, such as alterations of bone metabolism, bone mineral absorption, and immune regulation. The potential of gut microbiome-targeted strategies in the prevention and treatment of OP was also evaluated.

Cite this article: Bone Joint Res 2020;9(8):524–530.

MicroRNAs (miRNAs) are a class of small non-coding RNAs that have emerged as potential predictive, prognostic, and therapeutic biomarkers, relevant to many pathophysiological conditions including limb immobilization, osteoarthritis, sarcopenia, and cachexia. Impaired musculoskeletal homeostasis leads to distinct muscle atrophies. Understanding miRNA involvement in the molecular mechanisms underpinning conditions such as muscle wasting may be critical to developing new strategies to improve patient management. MicroRNAs are powerful post-transcriptional regulators of gene expression in muscle and, importantly, are also detectable in the circulation. MicroRNAs are established modulators of muscle satellite stem cell activation, proliferation, and differentiation, however, there have been limited human studies that investigate miRNAs in muscle wasting. This narrative review summarizes the current knowledge as to the role of miRNAs in the skeletal muscle differentiation and atrophy, synthesizing the findings of published data.

Cite this article: Bone Joint Res 2020;9(11):798–807.

Objectives

Many in vitro studies have investigated the mechanism by which mechanical signals are transduced into biological signals that regulate bone homeostasis via periodontal ligament fibroblasts during orthodontic treatment, but the results have not been systematically reviewed. This review aims to do this, considering the parameters of various in vitro mechanical loading approaches and their effects on osteogenic and osteoclastogenic properties of periodontal ligament fibroblasts.

Aims

Osteoarthritis (OA) is the most prevalent joint disease. However, the specific and definitive genetic mechanisms of OA are still unclear.

Long non-coding RNAs (lncRNAs) are transcripts longer than 200 nucleotides with limited coding potential, which have emerged as novel regulators in many biological and pathological processes, including growth, development, and oncogenesis. Accumulating evidence suggests that lncRNAs have a special role in the osteogenic differentiation of various types of cell, including stem cells from different sources such as embryo, bone marrow, adipose tissue and periodontal ligaments, and induced pluripotent stem cells. Involved in complex mechanisms, lncRNAs regulate osteogenic markers and key regulators and pathways in osteogenic differentiation. In this review, we provide insights into the functions and molecular mechanisms of lncRNAs in osteogenesis and highlight their emerging roles and clinical value in regenerative medicine and osteogenesis-related diseases.

Cite this article: J. Zhang, X. Hao, M. Yin, T. Xu, F. Guo. Long non-coding RNA in osteogenesis: A new world to be explored. Bone Joint Res 2019;8:73–80. DOI: 10.1302/2046-3758.82.BJR-2018-0074.R1.

Objectives

Diabetes mellitus (DM) is known to impair fracture healing. Increasing evidence suggests that some microRNA (miRNA) is involved in the pathophysiology of diabetes and its complications. We hypothesized that the functions of miRNA and changes to their patterns of expression may be implicated in the pathogenesis of impaired fracture healing in DM.

Objectives

Osteoporosis is a metabolic disease resulting in progressive loss of bone mass as measured by bone mineral density (BMD). Physical exercise has a positive effect on increasing or maintaining BMD in postmenopausal women. The contribution of exercise to the regulation of osteogenesis in osteoblasts remains unclear. We therefore investigated the effect of exercise on osteoblasts in ovariectomized mice.

MicroRNAs (miRNAs ) are small non-coding RNAs that regulate gene expression. We hypothesised that the functions of certain miRNAs and changes to their patterns of expression may be crucial in the pathogenesis of nonunion. Healing fractures and atrophic nonunions produced by periosteal cauterisation were created in the femora of 94 rats, with 1:1 group allocation. At post-fracture days three, seven, ten, 14, 21 and 28, miRNAs were extracted from the newly generated tissue at the fracture site. Microarray and real-time polymerase chain reaction (PCR) analyses of day 14 samples revealed that five miRNAs, miR-31a-3p, miR-31a-5p, miR-146a-5p, miR-146b-5p and miR-223-3p, were highly upregulated in nonunion. Real-time PCR analysis further revealed that, in nonunion, the expression levels of all five of these miRNAs peaked on day 14 and declined thereafter.

Our results suggest that miR-31a-3p, miR-31a-5p, miR-146a-5p, miR-146b-5p and miR-223-3p may play an important role in the development of nonunion. These findings add to the understanding of the molecular mechanism for nonunion formation and may lead to the development of novel therapeutic strategies for its treatment.

Cite this article: Bone Joint J 2015; 97-B:1144–51.

Objectives

In order to screen the altered gene expression profile in peripheral blood mononuclear cells of patients with osteoporosis, we performed an integrated analysis of the online microarray studies of osteoporosis.

Introduction

The pathogenesis of rotator cuff disease (RCD) is complex and not fully understood. This systematic review set out to summarise the histological and molecular changes that occur throughout the spectrum of RCD.