Targeting CCN Proteins in Rheumatoid Arthritis and Osteoarthritis

Fibrosis factor CTGF facilitates VCAM‑1‑dependent monocyte adhesion to osteoarthritis synovial fibroblasts via the FAK and JNK pathways

Osteoarthritis (OA) is a long‑term, degenerative joint disease that presents significant clinical challenges and imposes considerable financial burdens. Fibrosis is closely intertwined with the pathogenesis of various degenerative diseases, including OA. Using data from the GDS5401 dataset, the present study determined that expression levels of the fibrosis factor connective tissue growth factor (CTGF) were significantly higher in OA patients than in normal individuals. The present study also identified CTGF elevated expression levels in both OA patients compared with healthy controls and in rats with anterior cruciate ligament transection‑induced OA versus controls. Stimulating OA synovial fibroblasts (OASFs) with CTGF was shown to promote vascular cell adhesion molecule‑1 (VCAM‑1) production, thereby facilitating monocyte adhesion to OASFs. Analysis of a large dataset revealed that monocytes are the only mononuclear cells with significantly elevated levels in OA patients. It also appeared that CTGF‑induced VCAM‑1 production and monocyte adhesion were mediated via the focal adhesion kinase and JNK pathways. These findings suggest that CTGF contributes to OA progression by enhancing monocyte adhesion to the synovial membrane.

Effects and Significance of Dicliptera chinensis Polysaccharide on the Expression of Transforming Growth Factor β1/Connective Tissue Growth Factor Pathway in the Masseter and Head and Neck Skin of Rats With Radiation-Induced Fibrosis

PURPOSE

To investigate whether Dicliptera chinensis polysaccharide (DCP) can alleviate radiation-induced fibrosis of masseter and head and neck skin.

METHODS

SD rats were divided into the control, the irradiation (IR), the IR + low dose DCP (200 mg/kg), and the IR + high dose DCP (400 mg/kg) groups. The head and neck of rats in the last 3 groups received a single dose of 18 Gy X-ray. At 1st, 2nd, 4th week (w) after radiation, haematoxylin and eosin staining were performed on masseter and skin to observe the histopathological changes; immunohistochemistry staining was performed to observe the pathological changes of the skin; Masson staining was performed on masseter and skin to observe the collagen deposition; western blot analysis was used on masseter to calculate the relative transforming growth factor β1 (TGF-β1), connective tissue growth factor (CTGF) expressions; ELISA was used to detect the contents of TGF-β1 and CTGF in skin and the contents of type I and type III collagens in masseter and skin.

RESULTS

In terms of skin, compared to the IR group, the IR + high-dose DCP group exhibited relatively smaller changes in skin structure, lower levels of TGF-β1 and CTGF; thinner skin thickness was observed at the 4th w after radiation; and the positive rates of collagen fibre and the optical densities of type I and type III collagens were lower at the 2nd and 4th w. For the masseter, compared to the IR group, the morphological changes were improved and the expression levels of TGF-β1 and CTGF proteins decreased in the 2 DCP dose groups at 2nd and 4th w.

CONCLUSION

DCP can reduce the formation and accumulation of type I and type III collagens after IR and ameliorate radiation-induced fibrosis of masseter and skin by down-regulating the expressions of TGF-β1 and CTGF.

Recent advances in osteoarthritis research: A review of treatment strategies, mechanistic insights, and acupuncture

Osteoarthritis (OA) is a chronic joint condition affecting millions worldwide, characterized by the gradual degeneration of joint cartilage, leading to pain, stiffness, and functional impairment. Although the pathogenesis of OA is not fully understood, the roles of inflammation, metabolic dysregulation, and biomechanical stress are increasingly recognized. Current treatments, including pharmacotherapy, physical therapy, and surgical interventions, aim to alleviate symptoms and improve quality of life, yet they face limitations and challenges. In recent years, researchers have explored a variety of new treatment strategies, such as molecular targeted therapy, biologic treatments, regenerative medicine, and lifestyle modifications, aiming to directly address the root causes and complex mechanisms of OA. This review aims to summarize the latest research advancements to provide fresh perspectives for clinical treatment and lay the foundation for future research and development of treatment strategies for OA.

Associations between neutrophil percentage to albumin ratio and rheumatoid arthritis versus osteoarthritis: a comprehensive analysis utilizing the NHANES database

Objectives

The association between the neutrophil percentage to albumin ratio (NPAR) and the risk of osteoarthritis (OA) and rheumatoid arthritis (RA) remains unclear. This study aims to investigate the association between NPAR and the risk of OA and RA.

Methods

This cross-sectional study analyzed data from 92,062 American adults in the NHANES database between 1999 and 2016. Various statistical analyses were conducted to investigate the associations between NPAR and the risks of OA and RA, including multivariable logistic regression, subgroup analysis, smooth curve fitting, and threshold effect analysis.

Results

After screening, the final study population included 36,147 participants, with 3,881 individuals diagnosed with OA and 2,178 with RA. After adjusting for confounding factors, higher NPAR levels were associated with an increased risk of RA (OR=1.05; 95% CI: 1.03-1.07; P <0.0001), but not with OA (OR=1.01; 95% CI: 0.99-1.02; P =0.755). This association was remarkably consistent across subgroups by age, sex, body mass index (BMI), alcohol consumption, hypertension, diabetes, and smoking status. Further analyses using curve fitting and threshold effect models revealed a nonlinear association between NPAR and RA, with an inflection point identified at 15.56.

Conclusion

High levels of NPAR is positively associated with the prevalence of RA. This provides us with new insights for the management and treatment of RA patients.

Unlocking the therapeutic potential of WISP-1: A comprehensive exploration of its role in age-related musculoskeletal disorders

As the global population ages, the incidence of age-related musculoskeletal diseases continues to increase, driven by numerous complex and poorly understood factors. WNT-1 inducible secreted protein 1 (WISP-1), a secreted matrix protein, plays a critical role in the growth and development of the musculoskeletal system, including chondrogenesis, osteogenesis, and myogenesis. Numerous in vivo and in vitro studies have demonstrated that WISP-1 is significantly upregulated in age-related musculoskeletal conditions, such as osteoarthritis, osteoporosis, and sarcopenia, suggesting its involvement in the pathogenesis of these diseases. Regulating WISP-1 expression holds promise as a therapeutic strategy for improving musculoskeletal function, potentially offering new avenues for treating age-related musculoskeletal diseases in clinical practice. This review highlights the signaling pathways associated with WISP-1, its physiological roles within the musculoskeletal system, and its therapeutic potential in treating age-related musculoskeletal disorders.

ER stress-induced YAP upregulation leads to chondrocyte phenotype loss in age-related osteoarthritis

Background

Osteoarthritis (OA) is a common degenerative joint disease, leading to pain and restricted mobility. Age-related endoplasmic reticulum (ER) stress has been implicated in the pathogenesis of OA, but the underlying mechanisms remain unclear. This study aims to explore the relationship between age-related ER stress, YAP overexpression, and chondrocyte phenotype loss in the development of OA.

Methods

Cartilage samples were collected from patients undergoing amputation, and age-related ER stress markers and YAP expression were assessed using immunohistochemical staining and qPCR. Transgenic mice with cartilage-specific YAP overexpression (YAPOE) were created, and Pamrevlumab was administered to evaluate its therapeutic effects.

Results

Higher expression of ER stress markers and YAP were showed in aged tissues compared to younger tissues. YAP overexpression led to decreased levels of cartilage phenotype markers and increased osteogenesis-related proteins. In vivo, YAPOE mice exhibited OA-like cartilage degeneration, which was mitigated by Pamrevlumab treatment.

Conclusion

Age-related ER stress induces YAP overexpression, contributing to OA pathogenesis. Pamrevlumab effectively prevents this phenotype loss in YAPOE mice, suggesting its potential as a therapeutic agent for OA. These findings provide new insights into the molecular mechanisms of OA and highlight the importance of targeting the ER stress-YAP-CTGF signaling pathway in OA treatment and prevention.

An Equine Protein Atlas Highlights Synovial Fluid Proteome Dynamics during Experimentally LPS-Induced Arthritis

In human proteomics, substantial efforts are ongoing to leverage large collections of mass spectrometry (MS) fragment ion spectra into extensive spectral libraries (SL) as a resource for data independent acquisition (DIA) analysis. Currently, such initiatives in equine research are still missing. Here we present a large-scale equine SL, comprising 6394 canonical proteins and 89,329 unique peptides, based on data dependent acquisition analysis of 75 tissue and body fluid samples from horses. The SL enabled large-scale DIA-MS based quantification of the same samples to generate a quantitative equine protein distribution atlas to infer dominant proteins in different organs and body fluids. Data mining revealed 163 proteins uniquely identified in a specific type of tissue or body fluid, serving as a starting point to determine tissue-specific or tissue-type-specific proteins. We showcase the SL by highlighting proteome dynamics in equine synovial fluid samples during experimental lipopolysaccharide-induced arthritis. A fuzzy c-means cluster analysis pinpointed SERPINB1, ATRN, NGAL, LTF, MMP1, and LBP as putative biomarkers for joint inflammation. This SL provides an extendable resource for future equine studies employing DIA-MS.

Generation of cytotoxic aptamers specifically targeting fibroblast-like synoviocytes by CSCT-SELEX for treatment of rheumatoid arthritis

OBJECTIVES

Rheumatoid arthritis (RA) is an autoimmune disease characterised by aggressive fibroblast-like synoviocytes (FLSs). Very few RA patients-derived FLSs (RA-FLSs)-specific surface signatures have been identified, and there is currently no approved targeted therapy for RA-FLSs. This study aimed to screen therapeutic aptamers with cell-targeting and cytotoxic properties against RA-FLSs and to uncover the molecular targets and mechanism of action of the screened aptamers.

METHODS

We developed a cell-specific and cytotoxic systematic evolution of ligands by exponential enrichment (CSCT-SELEX) method to screen the therapeutic aptamers without prior knowledge of the surface signatures of RA-FLSs. The molecular targets and mechanisms of action of the screened aptamers were determined by pull-down assays and RNA sequencing. The therapeutic efficacy of the screened aptamers was examined in arthritic mouse models.

RESULTS

We obtained an aptamer SAPT8 that selectively recognised and killed RA-FLSs. The molecular target of SAPT8 was nucleolin (NCL), a shuttling protein overexpressed on the surface and involved in the tumor-like transformation of RA-FLSs. Mechanistically, SAPT8 interacted with the surface NCL and was internalised to achieve lysosomal degradation of NCL, leading to the upregulation of proapoptotic p53 and downregulation of antiapoptotic B-cell lymphoma 2 (Bcl-2) in RA-FLSs. When administrated systemically to arthritic mice, SAPT8 accumulated in the inflamed FLSs of joints. SAPT8 monotherapy or its combination with tumour necrosis factor (TNF)-targeted biologics was shown to relieve arthritis in mouse models.

CONCLUSIONS

CSCT-SELEX could be a promising strategy for developing cell-targeting and cytotoxic aptamers. SAPT8 aptamer selectively ablates RA-FLSs via modulating NCL-p53/Bcl-2 signalling, representing a potential alternative or complementary therapy for RA.

Extensive study of CCN4, VCAM-1, MMP-3, and GM-CSF as reliable markers for disease activity in rheumatoid arthritis

Background

The involvement of Wnt-1-induced secreted protein-1 (WISP1/CCN4) in several inflammatory reaction has recently been proposed. Nevertheless, this protein's involvement in rheumatoid arthritis (RA) remains debated. Associations between poorly diagnosed RA and several classical markers derived from demography and biochemistry have been reported.

Aim

We sought to investigate the reliability and effectiveness of serum concentrations of CCN4, vascular cell adhesion molecule-1 (VCAM-1), matrix melloprotenase-3 (MMP-3), and granulocyte-macrophage colony-stimulating factor (GM-CSF) in monitoring and predicting RA and bone damage, and their correlation with RA disease course.

Methods

The study analyzed 128 patients with RA, comprising 68 newly diagnosed and 60 previously diagnosed patients, as well as 60 controls. Biomarker levels were measured with enzyme linked immuno-sorbent assays. Routine laboratory parameters such as serological, clinical, biochemical, and hematological parameters were additionally measured. Demography, anthropometry, and clinical symptom data were collected through interviews and a questionnaire. The joint disease activity score 28 (DAS28) was used to determine disease activity.

Results

Concentrations of four biomarkers were significantly higher in the RA group than the healthy controls. Elevated biomarker concentrations were also observed in patients with high, rather than moderate or low, DAS28-ESR activity status, except for monocyte count, hematocrit (%), and urea level. Furthermore, CCN4 level positively correlated with VCAM-1, MMP-3, and GM-CSF levels, DA-S28-CRP and DAS28-ESR. The levels of three predictive markers, CCN4, VCAM-1, and MMP-3, were elevated in non-treated patients, whereas GM-CSF level showed no difference. The highest area under the curve was 73.3% for CCN4, with 93.3% sensitivity and 64.7% specificity.

Conclusion

Our data suggest that CCN4 can be reliably used to indicate activity and therapeutic response associated with RA, thus facilitating earlier RA diagnosis.

Harmonizing hope: navigating the osteoarthritis melody through the CCL2/CCR2 axis for innovative therapeutic avenues

Osteoarthritis (OA) is characterized by a complex interplay of molecular signals orchestrated by the CCL2/CCR2 axis. The pathogenesis of OA has been revealed to be influenced by a multifaceted effect of CCL2/CCR2 signaling on inflammation, cartilage degradation, and joint homeostasis. The CCL2/CCR2 axis promotes immune cell recruitment and tips the balance toward degeneration by influencing chondrocyte behavior. Insights into these intricate pathways will offer novel therapeutic approaches, paving the way for targeted interventions that may redefine OA management in the future. This review article explores the molecular symphony through the lens of the CCL2/CCR2 axis, providing a harmonious blend of current knowledge and future directions on OA treatment. Furthermore, in this study, through a meticulous review of recent research, the key players and molecular mechanisms that amplify the catabolic cascade within the joint microenvironment are identified, and therapeutic approaches to targeting the CCL2/CCR axis are discussed.

Matricellular proteins: Potential biomarkers in head and neck cancer

The extracellular matrix (ECM) is a complex network of diverse multidomain macromolecules, including collagen, proteoglycans, and fibronectin, that significantly contribute to the mechanical properties of tissues. Matricellular proteins (MCPs), as a family of non-structural proteins, play a crucial role in regulating various ECM functions. They exert their biological effects by interacting with matrix proteins, cell surface receptors, cytokines, and proteases. These interactions govern essential cellular processes such as differentiation, proliferation, adhesion, migration as well as multiple signal transduction pathways. Consequently, MCPs are pivotal in maintaining tissue homeostasis while orchestrating intricate molecular mechanisms within the ECM framework. The expression level of MCPs in adult steady-state tissues is significantly low; however, under pathological conditions such as inflammation and cancer, there is a substantial increase in their expression. In recent years, an increasing number of studies have focused on elucidating the role and significance of MCPs in the development and progression of head and neck cancer (HNC). During HNC progression, there is a remarkable upregulation in MCP expression. Through their distinctive structure and function, they actively promote tumor growth, invasion, epithelial-mesenchymal transition, and lymphatic metastasis of HNC cells. Moreover, by binding to integrins and modulating various signaling pathways, they effectively execute their biological functions. Furthermore, MCPs also hold potential as prognostic indicators. Although the star proteins of various MCPs have been extensively investigated, there remains a plethora of MCP family members that necessitate further scrutiny. This article comprehensively examines the functionalities of each MCP and highlights the research advancements in the context of HNC, with an aim to identify novel biomarkers for HNC and propose promising avenues for future investigations.

NGF facilitates ICAM-1-dependent monocyte adhesion and M1 macrophage polarization in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune inflammatory disorder in which monocytes adhering to synovial tissue differentiate into the pro-inflammatory M1 macrophage phenotype. Nerve growth factors (NGF) referred to as neurotrophins have been associated with inflammatory events; however, researchers have yet to elucidate the role of NGF in RA. Our examination of clinical tissue samples and analysis of data sourced from the Gene Expression Omnibus dataset unveiled elevated expression levels of M1 macrophage markers in human RA synovial tissue samples compared to normal tissue, with no such distinction observed for M2 markers. Furthermore, immunofluorescence data depicted increased expression levels of NGF and M1 macrophages in RA mice in contrast to normal mice. It appears that NGF stimulation facilitates macrophage polarization from the M0 to the M1 phenotype. It also appears that NGF promotes ICAM-1 production in human RA synovial fibroblasts, which enhances monocyte adhesion through the TrkA, MEK/ERK, and AP-1 signaling cascades. Our findings indicate NGF/TrkA axis as a novel target for the treatment of RA.

CCN3/NOV inhibition attenuates oxidative stress-induced apoptosis of mouse neural stem/progenitor cells by blocking the activation of p38 MAPK: An in vitro study

Neural stem/progenitor cells (NSPCs) hold immense promise in clinical applications, yet the harsh conditions resulting from central nervous system (CNS) injuries, particularly oxidative stress, lead to the demise of both native and transplanted NSPCs. Cellular communication network factor 3 (CCN3) exhibits a protective effect against oxidative stress in various cell types. This study investigates the impact of CCN3 on NSPCs apoptosis induced by oxidative stress. To establish models of primary cultured mouse NSPCs under oxidative stress, we exposed them to 50 μM H2O2 for 4 h. Remarkably, pre-exposing CCN3 exacerbated the H2O2-induced decline in cell viability in a concentration-dependent manner. However, employing gene-targeted siRNA to inhibit CCN3 protected NSPCs against H2O2-induced cell death. Conversely, CCN3 replenishment reversed this protective effect, as evidenced by TUNEL staining, the ratio of Cleaved-caspase-3 to Pro-caspase-3, and Bcl-2/Bax. Further investigations revealed that CCN3 pretreatment increased the phosphorylation level of p38 MAPK, while silencing CCN3 diminished p38 MAPK activation. Ultimately, the impact of changes in CCN3 protein expression on H2O2-induced apoptosis was nullified using anisomycin (a p38 activator) and SB 203580 (a p38 inhibitor). Our findings suggest that CCN3 inhibition prevents H2O2-induced cell death in cultured mouse NSPCs via the p38 pathway. These discoveries may contribute to the development of strategies aimed at enhancing the survival of both endogenous and transplanted NSPCs following CNS oxidative stress insults.

Association between weight-adjusted-waist index and the prevalence of rheumatoid arthritis and osteoarthritis: a population-based study

INTRODUCTION

The weight-adjusted-waist Index (WWI), an innovative metric for assessing obesity, exhibits superior efficacy in appraising lean muscle and adipose tissue mass relative to both the Body Mass Index (BMI) and Waist Circumference (WC). The objective of this research paper is to investigate the correlation between WWI and the incidence of Rheumatoid Arthritis (RA) and Osteoarthritis (OA).

METHODS

In this population-based study, we collected data from adult participants aged 20-80 years using the National Health and Nutrition Examination Survey (NHANES) conducted between 2011 and 2020 to analyze the association between WWI and the occurrence of RA and OA. NHANES, a nationally representative cross-sectional survey, is designed to evaluate the health and nutritional status of the U.S.

POPULATION

The current research incorporates an extensive, nationally representative sample of U.S. adults, utilizing weighted multivariate linear regression and smoothed curve fitting techniques to examine linear and non-linear relationships. Threshold effects were determined through a two-part linear regression model. Additionally, subgroup analyses and interaction tests were conducted to explore the connection between WWI and the incidence of RA and OA.

RESULTS

Our findings reveal a linear positive correlation between WWI and OA prevalence, indicating that an increase in WWI is linked to a heightened risk of OA. Conversely, a non-linear relationship was observed between WWI and RA prevalence, exhibiting a significant threshold effect with a saturation value of 11.21 cm/√kg. A positive association was detected to the left of the saturation point, while no significant association was present between the two variables to the right of the saturation point, suggesting a complex non-linear relationship between RA prevalence and WWI.

CONCLUSIONS

This investigation demonstrates a positive linear association between WWI and OA prevalence, as well as a complex non-linear relationship with RA prevalence in U.S. adults aged 20-80 years.

Research of Pathogenesis and Novel Therapeutics in Arthritis 3.0

Arthritis has a high prevalence globally and includes over 100 types, the most common of which are rheumatoid arthritis (RA), osteoarthritis (OA), psoriatic arthritis (PsA), and inflammatory arthritis [...].

CCN proteins: opportunities for clinical studies-a personal perspective

The diverse members of the CCN family now designated as CCN1(CYR61), CCN2 (CTGF), CCN3(NOV), CCN4(WISP1), CCN5(WISP2), CCN6(WISP3) are a conserved matricellular family of proteins exhibiting a spectrum of functional properties throughout all organs in the body. Interaction with cell membrane receptors such as integrins trigger intracellular signaling pathways. Proteolytically cleaved fragments (constituting the active domains) can be transported to the nucleus and perform transcriptional relevant functional activities. Notably, as also found in other protein families some members act opposite to others creating a system of functionally relevant checks and balances. It has become apparent that these proteins are secreted into the circulation, are quantifiable, and can serve as disease biomarkers. How they might also serve as homeostatic regulators is just becoming appreciated. In this review I have attempted to highlight the most recent evidence under the subcategories of cancer and non-cancer relevant that could lead to potential therapeutic approaches or ideas that can be factored into clinical advances. I have added my own personal perspective on feasibility.

Computational Fluid Dynamics (CFD) Model for Analysing the Role of Shear Stress in Angiogenesis in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is an autoimmune disease characterised by an attack on healthy cells in the joints. Blood flow and wall shear stress are crucial in angiogenesis, contributing to RA's pathogenesis. Vascular endothelial growth factor (VEGF) regulates angiogenesis, and shear stress is a surrogate for VEGF in this study. Our objective was to determine how shear stress correlates with the location of new blood vessels and RA progression. To this end, two models were developed using computational fluid dynamics (CFD). The first model added new blood vessels based on shear stress thresholds, while the second model examined the entire blood vessel network. All the geometries were based on a micrograph of RA blood vessels. New blood vessel branches formed in low shear regions (0.840-1.260 Pa). This wall-shear-stress overlap region at the junctions was evident in all the models. The results were verified quantitatively and qualitatively. Our findings point to a relationship between the development of new blood vessels in RA, the magnitude of wall shear stress and the expression of VEGF.

Knockdown SENP1 Suppressed the Angiogenic Potential of Mesenchymal Stem Cells by Impacting CXCR4-Regulated MRTF-A SUMOylation and CCN1 Expression

The angiogenic potential of mesenchymal stem cells (MSCs) is critical for adult vascular regeneration and repair, which is regulated by various growth factors and cytokines. In the current study, we report that knockdown SUMO-specific peptidase 1 (SENP1) stimulated the SUMOylation of MRTF-A and prevented its translocation into the nucleus, leading to downregulation of the cytokine and angiogenic factor CCN1, which significantly impacted MSC-mediated angiogenesis and cell migration. Further studies showed that SENP1 knockdown also suppressed the expression of a chemokine receptor CXCR4, and overexpression of CXCR4 could partially abrogate MRTF-A SUMOylation and reestablish the CCN1 level. Mutation analysis confirmed that SUMOylation occurred on three lysine residues (Lys-499, Lys-576, and Lys-624) of MRTF-A. In addition, SENP1 knockdown abolished the synergistic co-activation of CCN1 between MRTF-A and histone acetyltransferase p300 by suppressing acetylation on histone3K9, histone3K14, and histone4. These results revealed an important signaling pathway to regulate MSC differentiation and angiogenesis by MRTF-A SUMOylation involving cytokine/chemokine activities mediated by CCN1 and CXCR4, which may potentially impact a variety of cellular processes such as revascularization, wound healing, and progression of cancer.

Western Blot Protocols for Analysis of CCN Proteins and Fragments in Exosomes, Vesicle-Free Fractions, and Cells

Cellular Communication Network (CCN) proteins are growth factors that play key roles in many pathophysiological events, including bone formation, wound healing, and cancer. CCN factors and fragments generated by metalloproteinases-dependent cleavage are often associated with extracellular matrix (ECM) or small extracellular vesicles (sEVs) such as exosomes or matrix-coated vesicles. We provide reliable methods and protocols for Western blotting to analyze CCN factors and fragments in cells, sEVs, and vesicle-free fractions.

Comprehensive Method for Exosome Isolation and Proteome Analysis for Detection of CCN Factors in/on Exosomes

Cellular Communication Network (CCN) proteins are secretory growth factors often associated with extracellular matrix (ECM) and extracellular vesicles (EVs) such as exosomes or matrix-coated vesicles. CCN factors and fragments loaded on/in EVs may play key roles in cell communication networks in cancer biology, bone and cartilage metabolism, wound healing, and tissue regeneration. CCN proteins and EVs/exosomes are found in body fluids, such as blood, urine, milk, and supernatants of the two-dimensionally (2D) cultured cells and three-dimensionally (3D) cultured tissues, such as spheroids or organoids. More than ten methods to isolate exosomes or EVs have been developed with different properties. Here, we introduce comprehensive protocols for polymer-based precipitation, affinity purification, ultracentrifugation methods combined with the ultrafiltration method for isolating CCN-loaded exosomes/EVs from 2D and 3D cultured tissues, and proteome analysis using mass spectrometry for comprehensive analysis of CCN proteins.

Single-cell analysis reveals that Jinwu Gutong capsule attenuates the inflammatory activity of synovial cells in osteoarthritis by inhibiting AKR1C3

Jinwu Gutong capsule (JGC) is a traditional Chinese medicine formula for the treatment of osteoarthritis (OA). Synovitis is a typical pathological change in OA and promotes disease progression. Elucidating the therapeutic mechanism of JGC is crucial for the precise treatment of OA synovitis. In this study, we demonstrate that JGC effectively inhibits hyperproliferation, attenuates inflammation, and promotes apoptosis of synovial cells. Through scRNA-seq data analysis of OA synovitis, we dissected two distinct cell fates that influence disease progression (one fate led to recovery while the other fate resulted in deterioration), which illustrates the principles of fate determination. By intersecting JGC targets with synovitis hub genes and then mimicking picomolar affinity interactions between bioactive compounds and binding pockets, we found that the quercetin-AKR1C3 pair exhibited the best affinity, indicating that this pair constitutes the most promising molecular mechanism. In vitro experiments confirmed that the expression of AKR1C3 in synovial cells was reduced after JGC addition. Further overexpression of AKR1C3 significantly attenuated the therapeutic efficacy of JGC. Thus, we revealed that JGC effectively treats OA synovitis by inhibiting AKR1C3 expression.

CCN2 Facilitates IL-17 Production and Osteoclastogenesis in Human Osteoarthritis Synovial Fibroblasts by Inhibiting miR-655 Expression

Osteoarthritis (OA) is associated with extensive upregulation of osteoclastogenesis and subsequent bone breakdown. The CCN family protein connective tissue growth factor (CCN2, also called CCN2) enhances inflammatory cytokine production in OA disease. The cytokine interleukin (IL)-17 is known to induce osteoclastogenesis and bone erosion in arthritic disease. Our retrieval of data from the Gene Expression Omnibus (GEO) data set and clinical tissues exhibited higher CCN2 and IL-17 expression in OA synovial sample than in normal healthy samples. We observed the same phenomenon in synovial tissue from rats with anterior cruciate ligament transaction (ACLT)-elicited OA compared with synovial tissue from control healthy rats. We also found that CCN2 facilitated increases in IL-17 synthesis in human OA synovial fibroblasts (OASFs) and promoted osteoclast formation. CCN2 affected IL-17 production by reducing miR-655 expression through the ILK and Syk signaling cascades. Our findings improve our understanding about the effect of CCN2 in OA pathogenesis and, in particular, IL-17 production and osteoclastogenesis, which may help with the design of more effective OA treatments. © 2022 American Society for Bone and Mineral Research (ASBMR).

Hericium erinaceus Mycelium Ameliorates In Vivo Progression of Osteoarthritis

Osteoarthritis (OA) is an age-related disorder that affects the joints and causes functional disability. Hericium erinaceus is a large edible mushroom with several known medicinal functions. However, the therapeutic effects of H. erinaceus in OA are unknown. In this study, data from Sprague-Dawley rats with knee OA induced by anterior cruciate ligament transection (ACLT) indicated that H. erinaceus mycelium improves ACLT-induced weight-bearing asymmetry and minimizes pain. ACLT-induced increases in articular cartilage degradation and bone erosion were significantly reduced by treatment with H. erinaceus mycelium. In addition, H. erinaceus mycelium reduced the synthesis of proinflammatory cytokines interleukin-1β and tumor necrosis factor-α in OA cartilage and synovium. H. erinaceus mycelium shows promise as a functional food in the treatment of OA.

Exosomes derived from fibrinogen-like protein 1-overexpressing bone marrow-derived mesenchymal stem cells ameliorates rheumatoid arthritis

Rheumatoid arthritis (RA) is a most common chronic joint disease belonging to inflammatory autoimmune disease. The aim of this study was to determine the role and mechanism of bone marrow mesenchymal stem cells (BMSCs)-derived exosomes and fibrinogen-like protein 1 (FGL1) overexpression exosomes shuttled by BMSCs (FGL1-Exos) on RA. All of the exosomes were visualized by transmission electron microscope (TEM) and the characteristic proteins were detected by western blot. To investigate the therapeutic effect of FGL1-Exos, RA-FLSs were activated by TNF-α and RA rat model was established by collagen incomplete Freund's adjuvant. Cell viability, apoptosis, inflammation factors, and protein levels were detected by CCK-8, flow cytometry, enzyme-linked immunosorbent assay and western blot, respectively. Hematoxylin and eosin and safranin O staining were used to detect the histopathology changes. Cell apoptosis and FGL1 expression in knee joint were detected by immunofluorescence. The results showed that FGL1-Exos could inhibit the cell viability meanwhile increase the cell apoptosis in RA-FLSs. Meanwhile, FGL1-Exos could effectively suppress the inflammation score, joint destruction, and inflammatory response in RA rat model. FGL1-Exos directly inhibited cell apoptosis of RA-FLSs and RA rat model by suppressing the inflammatory cytokines, specific rheumatoid markers, immunological markers meanwhile meditating the NF-κB pathway. Our results indicate that FGL1 was a therapeutic potential target in RA therapy.

CTGF as a multifunctional molecule for cartilage and a potential drug for osteoarthritis

CTGF is a multifunctional protein and plays different roles in different cells and under different conditions. Pamrevlumab, a monoclonal antibody against CTGF, is an FDA approved drug for idiopathic pulmonary fibrosis (IPF) and Duchenne muscular dystrophy (DMD). Recent studies have shown that CTGF antibodies may potentially serve as a new drug for osteoarthritis (OA). Expression of CTGF is significantly higher in OA joints than in healthy counterparts. Increasing attention has been attracted due to its interesting roles in joint homeostasis. Joint homeostasis relies on normal cellular functions and cell-cell interactions. CTGF is essential for physiological activities of chondrocytes. Abnormal CTGF expression may cause cartilage degeneration. In this review, the physiological functions of CTGF in chondrocytes and related mechanisms are summarized. Changes in the related signaling pathways due to abnormal CTGF are discussed, which are contributing factors to inflammation, cartilage degeneration and synovial fibrosis in OA. The possibility of CTGF as a potential therapeutic target for OA treatment are reviewed.

Pan-Cancer Analysis Reveals Alternative Splicing Characteristics Associated With Immune-Related Adverse Events Elicited by Checkpoint Immunotherapy

Immune-related adverse events (irAEs) can impair the effectiveness and safety of immune checkpoint inhibitors (ICIs) and restrict the clinical applications of ICIs in oncology. The predictive biomarkers of irAE are urgently required for early diagnosis and subsequent management. The exact mechanism underlying irAEs remains to be fully elucidated, and the availability of predictive biomarkers is limited. Herein, we performed data mining by combining pharmacovigilance data and pan-cancer transcriptomic information to illustrate the relationships between alternative splicing characteristics and irAE risk of ICIs. Four distinct classes of splicing characteristics considered were associated with splicing factors, neoantigens, splicing isoforms, and splicing levels. Correlation analysis confirmed that expression levels of splicing factors were predictive of irAE risk. Adding DHX16 expression to the bivariate PD-L1 protein expression-fPD1 model markedly enhanced the prediction for irAE. Furthermore, we identified 668 and 1,131 potential predictors based on the correlation of the incidence of irAEs with splicing frequency and isoform expression, respectively. The functional analysis revealed that alternative splicing might contribute to irAE pathogenesis via coordinating innate and adaptive immunity. Remarkably, autoimmune-related genes and autoantigens were preferentially over-represented in these predictors for irAE, suggesting a close link between autoimmunity and irAE occurrence. In addition, we established a trivariate model composed of CDC42EP3-206, TMEM138-211, and IRX3-202, that could better predict the risk of irAE across various cancer types, indicating a potential application as promising biomarkers for irAE. Our study not only highlights the clinical relevance of alternative splicing for irAE development during checkpoint immunotherapy but also sheds new light on the mechanisms underlying irAEs.

New potential therapeutic approaches targeting synovial fibroblasts in rheumatoid arthritis

Synovial cells play a key role in joint destruction during chronic inflammation. In particular, activated synovial fibroblasts (SFs) undergo intrinsic alterations leading to an aggressive phenotype mediating cartilage destruction and bone erosion in rheumatoid arthritis (RA). Recent research has revealed a number of targets to control arthritogenic changes in SFs. Therefore, identification of SF phenotypes, control of epigenetic changes, modulation of cellular functions, or regulation of the activity of cation channels and different signaling pathways has been investigated. Although many of these approaches have shown efficacy in vitro and in animal models of RA, further research is needed to select the most relevant targets for drug development. This review is focused on the role of SFs as a potential strategy to discover novel therapeutic targets in RA aimed at preserving joint architecture and function.

Connective Tissue Growth Factor From Periosteal Tartrate Acid Phosphatase-Positive Monocytes Direct Skeletal Stem Cell Renewal and Fate During Bone Healing

The periosteum is critical for bone healing. Studies have shown that the periosteum contains periosteal stem cells (PSCs) with multidirectional differentiation potential and self-renewal ability. PSCs are activated in early fracture healing and are committed to the chondrocyte lineage, which is the basis of callus formation. However, the mechanism by which PSCs are activated and committed to chondrocytes in bone regeneration remains unclear. Here, we show that tartrate acid phosphatase (TRAP)-positive monocytes secrete CTGF to activate PSCs during bone regeneration. The loss function of TRAP-positive monocytes identifies their specific role during bone healing. Then, the secreted CTGF promotes endochondral ossification and activates PSCs in mouse bone fracture models. The secreted CTGF enhances PSC renewal by upregulating the expression of multiple pluripotent genes. CTGF upregulates c-Jun expression through αVβ5 integrin. Then, c-Jun transcription activates the transcription of the pluripotent genes Sox2, Oct4, and Nanog. Simultaneously, CTGF also activates the transcription and phosphorylation of Smad3 through αVβ5 integrin, which is the central gene in chondrogenesis. Our study indicates that TRAP-positive monocyte-derived CTGF promotes bone healing by activating PSCs and directing lineage commitment and that targeting PSCs may be an effective strategy for preventing bone non-union.

CCN proteins in the musculoskeletal system: current understanding and challenges in physiology and pathology

The acronym for the CCN family was recently revised to represent “cellular communication network”. These six, small, cysteine-enriched and evolutionarily conserved proteins are secreted matricellular proteins, that convey and modulate intercellular communication by interacting with structural proteins, signalling factors and cell surface receptors. Their role in the development and physiology of musculoskeletal system, constituted by connective tissues where cells are interspersed in the cellular matrix, has been broadly studied. Previous research has highlighted a crucial balance of CCN proteins in mesenchymal stem cell commitment and a pivotal role for CCN1, CCN2 and their alter ego CCN3 in chondrogenesis and osteogenesis; CCN4 plays a minor role and the role of CCN5 and CCN6 is still unclear. CCN proteins also participate in osteoclastogenesis and myogenesis. In adult life, CCN proteins serve as mechanosensory proteins in the musculoskeletal system providing a steady response to environmental stimuli and participating in fracture healing. Substantial evidence also supports the involvement of CCN proteins in inflammatory pathologies, such as osteoarthritis and rheumatoid arthritis, as well as in cancers affecting the musculoskeletal system and bone metastasis. These matricellular proteins indeed show involvement in inflammation and cancer, thus representing intriguing therapeutic targets. This review discusses the current understanding of CCN proteins in the musculoskeletal system as well as the controversies and challenges associated with their multiple and complex roles, and it aims to link the dispersed knowledge in an effort to stimulate and guide readers to an area that the writers consider to have significant impact and relevant potentialities.