Targeting CCN Proteins in Rheumatoid Arthritis and Osteoarthritis

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.