WNT1-induced Secreted Protein-1 (WISP1), a Novel Regulator of Bone Turnover and Wnt Signaling

A glucocorticoid spike derails muscle repair to heterotopic ossification after spinal cord injury

Why severe injury to the central nervous system (CNS) triggers the development of large neurogenic heterotopic ossifications (NHOs) within periarticular muscles remains unknown. We report that spinal cord injury (SCI) triggers a rapid corticosterone spike in mice, which is causal for NHO development because treatments with corticosterone or the synthetic glucocorticoid (GC) receptor (GR) agonist dexamethasone are sufficient to trigger heterotopic ossification and upregulate the expression of osteoinductive and osteogenic differentiation genes in injured muscles even without SCI. The central role for GR signaling in causing NHO is further demonstrated in mice deleted for the GR gene (Nr3c1), which no longer develop NHO after SCI. Furthermore, administration of clinical GR antagonists inhibits NHO development in mice with SCI. This study identifies endogenous GC as causing pathological NHO after CNS injury and suggests that GR antagonists may be of prophylactic use to prevent NHO development in victims of severe CNS injuries.

"Photo-Thermo-Electric" Dental Implant for Anti-Infection and Enhanced Osteoimmunomodulation

The dental implant market has experienced explosive growth, owing to the widespread acceptance of implants as the core of oral rehabilitation. Clinically, achieving simultaneous anti-infective effects and rapid osseointegration is a crucial but challenging task for implants. The demand for implants with long-term broad-spectrum antibacterial and immune-osteogenic properties is growing. Existing methods are limited by a lack of safety, efficiency, short-lasting anti-infective ability, and inadequate consideration of the immunomodulatory effects on osteogenesis. Herein, a ZnO/black TiO2-x heterojunction surface structure was designed as a near-infrared (NIR) light-responsive nanofilm immobilized on a titanium (Ti) implant surface. This nanofilm introduces abundant oxygen vacancies and heterojunctions, which enhance the photothermal and photoelectric abilities of Ti implants under NIR illumination by narrowing the band gap and improving interfacial charge transfer. The "photo-thermo-electric" implant exhibits excellent broad-spectrum antibacterial efficacy against three dental pathogenic bacteria (Porphyromonas gingivalis, Fusobacterium nucleatum, and Staphylococcus aureus, >99.4%) by destroying the bacterial membrane and increasing the production of intracellular reactive oxygen species. Additionally, the implant can effectively eliminate mature multispecies biofilms and kill bacteria inside the biofilms under NIR irradiation. Meanwhile, this implant can also induce the pro-regenerative transformation of macrophages and promote osteoblast proliferation and differentiation. Moreover, in vivo results confirmed the superior antibacterial and osteoimmunomodulatory properties of this dental implant. RNA sequencing revealed that the underlying osteogenic mechanisms involve activation of the Wnt/β-catenin signaling pathway and bone development. Overall, this versatile "photo-thermo-electric" platform endows implants with anti-infection and bone integration performance simultaneously, which holds great potential for dental implants.

Repurposing Niclosamide to Modulate Renal RNA-Binding Protein HuR for the Treatment of Diabetic Nephropathy in db/db Mice

Hu antigen R (HuR) plays a key role in regulating genes critical to the pathogenesis of diabetic nephropathy (DN). This study investigates the therapeutic potential of niclosamide (NCS) as an HuR inhibitor in DN. Uninephrectomized mice were assigned to four groups: normal control; untreated db/db mice terminated at 14 and 22 weeks, respectively; and db/db mice treated with NCS (20 mg/kg daily via i.p.) from weeks 18 to 22. Increased HuR expression was observed in diabetic kidneys from db/db mice, which was mitigated by NCS treatment. Untreated db/db mice exhibited obesity, progressive hyperglycemia, albuminuria, kidney hypertrophy and glomerular mesangial matrix expansion, increased renal production of fibronectin and a-smooth muscle actin, and decreased glomerular WT-1+-podocytes and nephrin expression. NCS treatment did not affect mouse body weight, but reduced blood glucose and HbA1c levels and halted the DN progression observed in untreated db/db mice. Renal production of inflammatory and oxidative stress markers (NF-κBp65, TNF-a, MCP-1) and urine MDA levels increased during disease progression in db/db mice but were halted by NCS treatment. Additionally, the Wnt1-signaling-pathway downstream factor, Wisp1, was identified as a key downstream mediator of HuR-dependent action and found to be markedly increased in db/db mouse kidneys, which was normalized by NCS treatment. These findings suggest that inhibition of HuR with NCS is therapeutic for DN by improving hyperglycemia, renal inflammation, and oxidative stress. The reduction in renal Wisp1 expression also contributes to its renoprotective effects. This study supports the potential of repurposing HuR inhibitors as a novel therapy for DN.

Sclerostin blockade inhibits bone resorption through PDGF receptor signaling in osteoblast lineage cells

While sclerostin-neutralizing antibodies (Scl-Abs) transiently stimulate bone formation by activating Wnt signaling in osteoblast lineage cells, they exert sustained inhibition of bone resorption, suggesting an alternate signaling pathway by which Scl-Abs control osteoclast activity. Since sclerostin can activate platelet-derived growth factor receptors (PDGFRs) in osteoblast lineage cells in vitro and PDGFR signaling in these cells induces bone resorption through M-CSF secretion, we hypothesized that the prolonged anticatabolic effect of Scl-Abs could result from PDGFR inhibition. We show here that inhibition of PDGFR signaling in osteoblast lineage cells is sufficient and necessary to mediate prolonged Scl-Ab effects on M-CSF secretion and osteoclast activity in mice. Indeed, sclerostin coactivates PDGFRs independently of Wnt/β-catenin signaling inhibition, by forming a ternary complex with LRP6 and PDGFRs in preosteoblasts. In turn, Scl-Ab prevents sclerostin-mediated coactivation of PDGFR signaling and consequent M-CSF upregulation in preosteoblast cultures, thereby inhibiting osteoclast activity in preosteoblast/osteoclast coculture assays. These results provide a potential mechanism explaining the dissociation between anabolic and antiresorptive effects of long-term Scl-Ab.

Osteoarthritis versus psoriasis arthritis: Physiopathology, cellular signaling, and therapeutic strategies

Osteoarthritis and psoriasis arthritis are two degenerative forms of arthritis that share similar yet also different manifestations at the histological, cellular, and clinical levels. Rheumatologists have marked them as two entirely distinct arthropathies. Given recent discoveries in disease initiation and progression, potential mechanisms, cellular signaling pathways, and ongoing clinical therapeutics, there are now more opportunities for discovering osteoarthritis drugs. This review summarized the osteoarthritis and psoriasis arthritis signaling pathways, crosstalk between BMP, WNT, TGF-β, VEGF, TLR, and FGF signaling pathways, biomarkers, and anatomical pathologies. Through bench research, we demonstrated that regenerative medicine is a promising alternative for treating osteoarthritis by highlighting significant scientific discoveries on entheses, multiple signaling blockers, and novel molecules such as immunoglobulin new antigen receptors targeted for potential drug evaluation. Furthermore, we offered valuable therapeutic approaches with a multidisciplinary strategy to treat patients with osteoarthritis or psoriasis arthritis in the coming future in the clinic.

Breast cancer remotely imposes a myeloid bias on haematopoietic stem cells by reprogramming the bone marrow niche

Myeloid cell infiltration of solid tumours generally associates with poor patient prognosis and disease severity1-13. Therefore, understanding the regulation of myeloid cell differentiation during cancer is crucial to counteract their pro-tumourigenic role. Bone marrow (BM) haematopoiesis is a tightly regulated process for the production of all immune cells in accordance to tissue needs14. Myeloid cells differentiate during haematopoiesis from multipotent haematopoietic stem and progenitor cells (HSPCs)15-17. HSPCs can sense inflammatory signals from the periphery during infections18-21 or inflammatory disorders22-27. In these settings, HSPC expansion is associated with increased myeloid differentiation28,29. During carcinogenesis, the elevation of haematopoietic growth factors supports the expansion and differentiation of committed myeloid progenitors5,30. However, it is unclear whether cancer-related inflammation also triggers demand-adapted haematopoiesis at the level of multipotent HSPCs. In the BM, HSPCs reside within the haematopoietic niche which delivers HSC maintenance and differentiation cues31-35. Mesenchymal stem cells (MSCs) are a major cellular component of the BM niche and contribute to HSC homeostasis36-41. Modifications of MSCs in systemic disorders have been associated with HSC differentiation towards myeloid cells22,42. It is unknown if MSCs are regulated in the context of solid tumours and if their myeloid supportive activity is impacted by cancer-induced systemic changes. Here, using unbiased transcriptomic analysis and in situ imaging of HSCs and the BM niche during breast cancer, we show that both HSCs and MSCs are transcriptionally and spatially modified. We demonstrate that breast tumour can distantly remodel the cellular cross-talks in the BM niche leading to increased myelopoiesis.

Wnt5a: A promising therapeutic target for inflammation, especially rheumatoid arthritis

BACKGROUND

Wnt5a is a member of the Wnt protein family, which acts on classical or multiple non-classical Wnt signaling pathways by binding to different receptors. The expression regulation and signal transduction of Wnt5a is closely related to the inflammatory response. Abnormal activation of Wnt5a signaling is an important part of inflammation and rheumatoid arthritis (RA).

OBJECTIVES

This paper mainly focuses on Wnt5a protein and its mediated signaling pathway, summarizes the latest research progress of Wnt5a in the pathological process of inflammation and RA, and looks forward to the main directions of Wnt5a in RA research, aiming to provide a theoretical basis for the prevention and treatment of RA diseases by targeting Wnt5a.

RESULTS

Wnt5a is highly expressed in activated blood vessels, histocytes and synoviocytes in inflammatory diseases such as sepsis, sepsis, atherosclerosis and rheumatoid arthritis. It mediates the production of pro-inflammatory cytokines and chemokines, regulates the migration and recruitment of various immune effector cells, and thus participates in the inflammatory response. Wnt5a plays a pathological role in synovial inflammation and bone destruction of RA, and may be an important clinical therapeutic target for RA.

CONCLUSION

Wnt5a is involved in the pathological process of inflammation and interacts with inflammatory factors. Wnt5a may be a new target for regulating the progression of RA disease and intervening therapy because of its multi-modal effects on the etiology of RA, especially as a regulator of osteoclast activity and inflammation.

Significance of CCNs in liver regeneration

The liver has an inherent regenerative capacity via hepatocyte proliferation after mild-to-modest damage. When hepatocytes exhaust their replicative ability during chronic or severe liver damage, liver progenitor cells (LPC), also termed oval cells (OC) in rodents, are activated in the form of ductular reaction (DR) as an alternative pathway. LPC is often intimately associated with hepatic stellate cells (HSC) activation to promote liver fibrosis. The Cyr61/CTGF/Nov (CCN) protein family consists of six extracellular signaling modulators (CCN1-CCN6) with affinity to a repertoire of receptors, growth factors, and extracellular matrix proteins. Through these interactions, CCN proteins organize microenvironments and modulate cell signalings in a diverse variety of physiopathological processes. In particular, their binding to subtypes of integrin (αvβ5, αvβ3, α6β1, αvβ6, etc.) influences the motility and mobility of macrophages, hepatocytes, HSC, and LPC/OC during liver injury. This paper summarizes the current understanding of the significance of CCN genes in liver regeneration in relation to hepatocyte-driven or LPC/OC-mediated pathways. Publicly available datasets were also searched to compare dynamic levels of CCNs in developing and regenerating livers. These insights not only add to our understanding of the regenerative capability of the liver but also provide potential targets for the pharmacological management of liver repair in the clinical setting. Ccns in liver regeneration Restoring damaged or lost tissues requires robust cell growth and dynamic matrix remodeling. Ccns are matricellular proteins highly capable of influencing cell state and matrix production. Current studies have identified Ccns as active players in liver regeneration. Cell types, modes of action, and mechanisms of Ccn induction may vary depending on liver injuries. Hepatocyte proliferation is a default pathway for liver regeneration following mild-to-modest damages, working in parallel with the transient activation of stromal cells, such as macrophages and hepatic stellate cells (HSC). Liver progenitor cells (LPC), also termed oval cells (OC) in rodents, are activated in the form of ductular reaction (DR) and are associated with sustained fibrosis when hepatocytes lose their proliferative ability in severe or chronic liver damage. Ccns may facilitate both hepatocyte regeneration and LPC/OC repair via various mediators (growth factors, matrix proteins, integrins, etc.) for cell-specific and context-dependent functions.

Structural insights into regulation of CCN protein activities and functions

CCN proteins play important functions during development, in repair mechanisms following tissue injury, as well as in pathophysiologic mechanisms of metastasis of cancer. CCNs are secreted proteins that have a multimodular structure and are categorized as matricellular proteins. Although the prevailing view is that CCN proteins regulate biologic processes by interacting with a wide array of other proteins in the microenvironment of the extracellular matrix, the molecular mechanisms of action of CCN proteins are still poorly understood. Not dissuading the current view, however, the recent appreciation that these proteins are signaling proteins in their own right and may even be considered preproproteins controlled by endopeptidases to release a C-terminal bioactive peptide has opened new avenues of research. Also, the recent resolution of the crystal structure of two of the domains of CCN3 have provided new knowledge with implications for the entire CCN family. These resolved structures in combination with structural predictions based upon the AlphaFold artificial intelligence tool provide means to shed new light on CCN functions in context of the notable literature in the field. CCN proteins have emerged as important therapeutic targets in several disease conditions, and clinical trials are currently ongoing. Thus, a review that critically discusses structure - function relationship of CCN proteins, in particular as it relates to interactions with other proteins in the extracellular milieu and on the cell surface, as well as to cell signaling activities of these proteins, is very timely. Suggested mechanism for activation and inhibition of signaling by the CCN protein family (graphics generated with BioRender.com ).

The regulation and functions of the matricellular CCN proteins induced by shear stress

Shear stress is a frictional drag generated by the flow of fluid, such as blood or interstitial fluid, and plays a critical role in regulating cellular gene expression and functional phenotype. The matricellular CCN family proteins are dynamically regulated by shear stress of different flow patterns, and their expression significantly alters the microenvironment of cells. Secreted CCN proteins mainly bind to several cell surface integrin receptors to mediate their diverse functions in regulating cell survival, function, and behavior. Gene-knockout studies indicate major functions of CCN proteins in the cardiovascular and skeletal systems, the two primary systems in which CCN expressions are regulated by shear stress. In the cardiovascular system, the endothelium is directly exposed to vascular shear stress. Unidirectional laminar blood flow generates laminar shear stress, which promotes a mature endothelial phenotype and upregulates anti-inflammatory CCN3 expression. In contrast, disturbed flow generates oscillatory shear stress, which induces endothelial dysfunction through the induction of CCN1 and CCN2. Shear-induced CCN1 binds to integrin α6β1 and promotes superoxide production, NF-κB activation, and inflammatory gene expression in endothelial cells. Although the interaction between shear stress and CCN4-6 is not clear, CCN 4 exhibits a proinflammatory property and CCN5 inhibits vascular cell growth and migration. The crucial roles of CCN proteins in cardiovascular development, homeostasis, and disease are evident but not fully understood. In the skeletal system, mechanical loading on bone generates shear stress from interstitial fluid in the lacuna-canalicular system and promotes osteoblast differentiation and bone formation. CCN1 and CCN2 are induced and potentially mediate fluid shear stress mechanosensing in osteocytes. However, the exact roles of interstitial shear stress-induced CCN1 and CCN2 in bone are still not clear. In contrast to other CCN family proteins, CCN3 inhibits osteoblast differentiation, although its regulation by interstitial shear stress in osteocytes has not been reported. The induction of CCN proteins by shear stress in bone and their functions remain largely unknown and merit further investigation. This review discusses the expression and functions of CCN proteins regulated by shear stress in physiological conditions, diseases, and cell culture models. The roles between CCN family proteins can be compensatory or counteractive in tissue remodeling and homeostasis.

Interaction of tumor-associated microglia/macrophages and cancer stem cells in glioma

Glioma is the most common tumor of the primary central nervous system, and its malignant phenotype has been shown to be closely related to glioma stem cells (GSCs). Although temozolomide has significantly improved the therapeutic outcome of glioma with a high penetration rate of the blood-brain barrier, resistance is often present in patients. Moreover, evidence has shown that the crosstalk between GSCs and tumor-associated microglia/macrophages (TAMs) affect the clinical occurrence, growth, and multi-tolerance of chemoradiotherapy in gliomas. Here, we highlight its vital roles in the maintenance of the stemness of GSCs and the ability of GSCs to recruit TAMs to the tumor microenvironment and promote their polarization into tumor-promoting macrophages, hence providing groundwork for future research into new treatment strategies of cancer.

Evaluation of the Effects of CCN4 on Pancreatic Beta Cell Proliferation

Expanding the number of insulin-producing beta cells through reactivation of their replication has been proposed as a therapy to prevent or delay the appearance of diabetes. Using antibody arrays, we identified CCN4/Wisp1 as a circulating factor enriched in preweaning mice, a period in which beta cells exhibit a dramatic increase in number. This finding led us to investigate the involvement of CCN4 in beta cell proliferation. We demonstrated that CCN4 promotes adult beta cell proliferation in vitro in cultured isolated islets, and in vivo in islets transplanted into the anterior chamber of the eye. In this chapter, we present the methodology that was used to study proliferation in both settings.

HuR-dependent expression of Wisp1 is necessary for TGFβ-induced cardiac myofibroblast activity

Cardiac fibrosis is regulated by the activation and phenotypic switching of quiescent cardiac fibroblasts to active myofibroblasts, which have extracellular matrix (ECM) remodeling and contractile functions which play a central role in cardiac remodeling in response to injury. Here, we show that expression and activity of the RNA binding protein HuR is increased in cardiac fibroblasts upon transformation to an active myofibroblast. Pharmacological inhibition of HuR significantly blunts the TGFβ-dependent increase in ECM remodeling genes, total collagen secretion, in vitro scratch closure, and collagen gel contraction in isolated primary cardiac fibroblasts, suggesting a suppression of TGFβ-induced myofibroblast activation upon HuR inhibition. We identified twenty-four mRNA transcripts that were enriched for HuR binding following TGFβ treatment via photoactivatable ribonucleoside-enhanced crosslinking and immunoprecipitation (PAR-CLIP). Eleven of these HuR-bound mRNAs also showed significant co-expression correlation with HuR, αSMA, and periostin in primary fibroblasts isolated from the ischemic-zone of infarcted mouse hearts. Of these, WNT1-inducible signaling pathway protein-1 (Wisp1; Ccn4), was the most significantly associated with HuR expression in fibroblasts. Accordingly, we found Wisp1 expression to be increased in cardiac fibroblasts isolated from the ischemic-zone of mouse hearts following ischemia/reperfusion, and confirmed Wisp1 expression to be HuR-dependent in isolated fibroblasts. Finally, addition of exogenous recombinant Wisp1 partially rescued myofibroblast-induced collagen gel contraction following HuR inhibition, demonstrating that HuR-dependent Wisp1 expression plays a functional role in HuR-dependent MF activity downstream of TGFβ. In conclusion, HuR activity is necessary for the functional activation of primary cardiac fibroblasts in response to TGFβ, in part through post-transcriptional regulation of Wisp1.

Analysis of CCN4/WISP1 Effects on Joint Tissues Using Gain- and Loss-of-Function Approaches

The matricellular protein Wnt-induced secreted protein 1 (WISP1) is the fourth member of the CCN family of proteins, which has been shown to affect tissues of the musculoskeletal system. In the context of the musculoskeletal disorder osteoarthritis, our lab studied the function of CCN4/WISP1 in joint tissues, including synovium and cartilage, using both gain- and loss-of-function approaches. In mice, this was done by genetic engineering and recombination to generate mice deficient in CCN4/WISP1 protein. Various experimental models of osteoarthritis with different characteristics were induced in these mice. Moreover, CCN4/WISP1 levels in joints were experimentally increased by adenoviral transfections. Osteoarthritis pathology was determined using histology, and the effect of different CCN4/WISP1 levels on gene expression was evaluated in individual tissues. Effects of high levels of CCN4/WISP1 on chondrocytes were studied with an in vitro chondrocyte pellet model. In this chapter, we describe the procedures to conduct these experiments.

Multi-ancestry genome-wide association analyses identify novel genetic mechanisms in rheumatoid arthritis

Rheumatoid arthritis (RA) is a highly heritable complex disease with unknown etiology. Multi-ancestry genetic research of RA promises to improve power to detect genetic signals, fine-mapping resolution and performances of polygenic risk scores (PRS). Here, we present a large-scale genome-wide association study (GWAS) of RA, which includes 276,020 samples from five ancestral groups. We conducted a multi-ancestry meta-analysis and identified 124 loci (P < 5 × 10-8), of which 34 are novel. Candidate genes at the novel loci suggest essential roles of the immune system (for example, TNIP2 and TNFRSF11A) and joint tissues (for example, WISP1) in RA etiology. Multi-ancestry fine-mapping identified putatively causal variants with biological insights (for example, LEF1). Moreover, PRS based on multi-ancestry GWAS outperformed PRS based on single-ancestry GWAS and had comparable performance between populations of European and East Asian ancestries. Our study provides several insights into the etiology of RA and improves the genetic predictability of RA.

A WISP1 antibody inhibits MRTF signaling to prevent the progression of established liver fibrosis

Fibrosis is the major risk factor associated with morbidity and mortality in patients with non-alcoholic steatohepatitis (NASH)-driven chronic liver disease. Although numerous efforts have been made to identify the mediators of the initiation of liver fibrosis, the molecular underpinnings of fibrosis progression remain poorly understood, and therapies to arrest liver fibrosis progression are elusive. Here, we identify a pathway involving WNT1-inducible signaling pathway protein 1 (WISP1) and myocardin-related transcription factor (MRTF) as a central mechanism driving liver fibrosis progression through the integrin-dependent transcriptional reprogramming of myofibroblast cytoskeleton and motility. In mice, WISP1 deficiency protects against fibrosis progression, but not fibrosis onset. Moreover, the therapeutic administration of a novel antibody blocking WISP1 halted the progression of existing liver fibrosis in NASH models. These findings implicate the WISP1-MRTF axis as a crucial determinant of liver fibrosis progression and support targeting this pathway by antibody-based therapy for the treatment of NASH fibrosis.

Fibroblast Growth Factors and Cellular Communication Network Factors: Intimate Interplay by the Founding Members in Cartilage

Fibroblast growth factors (FGFs) constitute a large family of signaling molecules that act in an autocrine/paracrine, endocrine, or intracrine manner, whereas the cellular communication network factors (CCN) family is composed of six members that manipulate extracellular signaling networks. FGFs and CCNs are structurally and functionally distinct, except for the common characteristics as matricellular proteins. Both play significant roles in the development of a variety of tissues and organs, including the skeletal system. In vertebrates, most of the skeletal parts are formed and grow through a process designated endochondral ossification, in which chondrocytes play the central role. The growth plate cartilage is the place where endochondral ossification occurs, and articular cartilage is left to support the locomotive function of joints. Several FGFs, including FGF-2, one of the founding members of this family, and all of the CCNs represented by CCN2, which is required for proper skeletal development, can be found therein. Research over a decade has revealed direct binding of CCN2 to FGFs and FGF receptors (FGFRs), which occasionally affect the biological outcome via FGF signaling. Moreover, a recent study uncovered an integrated regulation of FGF and CCN genes by FGF signaling. In this review, after a brief introduction of these two families, molecular and genetic interactions between CCN and FGF family members in cartilage, and their biological effects, are summarized. The molecular interplay represents the mutual involvement of the other in their molecular functions, leading to collaboration between CCN2 and FGFs during skeletal development.

Contribution to the 3R Principle: Description of a Specimen-Specific Finite Element Model Simulating 3-Point-Bending Tests in Mouse Tibiae

Bone mechanical properties are classically determined by biomechanical tests, which normally destroy the bones and disable further histological or molecular analyses. Thus, obtaining biomechanical data from bone usually requires an additional group of animals within the experimental setup. Finite element models (FEMs) may non-invasively and non-destructively simulate mechanical characteristics based on material properties. The present study aimed to establish and validate an FEM to predict the mechanical properties of mice tibiae. The FEM was established based on µCT (micro-Computed Tomography) data of 16 mouse tibiae. For validating the FEM, simulated parameters were compared to biomechanical data obtained from 3-point bending tests of the identical bones. The simulated and the measured parameters correlated well for bending stiffness (R2 = 0.9104, p < 0.0001) and yield displacement (R2 = 0.9003, p < 0.0001). The FEM has the advantage that it preserves the bones’ integrity, which can then be used for other analytical methods. By eliminating the need for an additional group of animals for biomechanical tests, the established FEM can contribute to reducing the number of research animals in studies focusing on bone biomechanics. This is especially true when in vivo µCT data can be utilized where multiple bone scans can be performed with the same animal at different time points. Thus, by partially replacing biomechanical experiments, FEM simulations may reduce the overall number of animals required for an experimental setup investigating bone biomechanics, which supports the 3R (replace, reduce, and refine) principle.

Potential therapeutic application of biophenols - plants secondary metabolites in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease showed that persistent inflammation in the joints, induces the cartilage destruction, bone erosion, and leukocyte infiltration in the synovium. RA mostly affects the joints of hands, feet, wrists, ankles, and knees. Each year, approximately 20-40 new cases are reported per lac population and the disease affects women more than men. The etiology of RA is still unknown, but many pathways have been identified as potential targets in its pathophysiology, including the PI3K/AKT signaling pathway, NF-κB signaling, Adenosine signaling, Wnt, SYK/BTK, and mTOR signaling pathways. Biophenol, plant secondary metabolite, is considered one of the most abundantly phytoconstituents to have potential anti-inflammatory effects associated with multiple pathways. These indicate that biophenols can be used for its protective effect on the development and symptoms of RA. The current review explores and discusses the role of different biophenols in the treatment of RA disease.

The Roles of Long-Term Hyperhomocysteinemia and Micronutrient Supplementation in the AppNL–G–F Model of Alzheimer’s Disease

A causal contribution of hyperhomocysteinemia to cognitive decline and Alzheimer’s disease (AD), as well as potential prevention or mitigation of the pathology by dietary intervention, have frequently been subjects of controversy. In the present in vivo study, we attempted to further elucidate the impact of elevated homocysteine (HCys) and homocysteic acid (HCA) levels, induced by dietary B-vitamin deficiency, and micronutrient supplementation on AD-like pathology, which was simulated using the amyloid-based App^NL–G–F knock-in mouse model. For this purpose, cognitive assessment was complemented by analyses of ex vivo parameters in whole blood, serum, CSF, and brain tissues from the mice. Furthermore, neurotoxicity of HCys and HCA was assessed in a separate in vitro assay. In confirmation of our previous study, older App^NL–G–F mice also exhibited subtle phenotypic impairment and extensive cerebral amyloidosis, whereas dietary manipulations did not result in significant effects. As revealed by proximity extension assay-based proteome analysis, the App^NL–G–F genotype led to an upregulation of AD-characteristic neuronal markers. Hyperhomocysteinemia, in contrast, indicated mainly vascular effects. Overall, since there was an absence of a distinct phenotype despite both a significant amyloid-β burden and serum HCys elevation, the results in this study did not corroborate the pathological role of amyloid-β according to the “amyloid hypothesis,” nor of hyperhomocysteinemia on cognitive performance. Nevertheless, this study aided in further characterizing the App^NL–G–F model and in elucidating the role of HCys in diverse biological processes. The idea of AD prevention with the investigated micronutrients, however, was not supported, at least in this mouse model of the disease.

A morphological study of adipose-derived stem cell sheets created with temperature-responsive culture dishes using scanning electron microscopy

Adipose-derived stem cell (ADSC) sheets have potential to be effective in various therapies. In this study, we first demonstrated that a cell sheet composed of human ADSCs could be created using a new temperature-responsive culture dish from the DIC Corporation. The dish can cause detachment of adherent cells due to temperature changes, but a few morphological analyses have evaluated the presence or absence of damage on the detached surface of cell sheet. To characterize our ADSC sheet, we tried to observe the surface of ADSC sheets with scanning electron microscope (SEM) using the ionic liquid, which enables the rapid preparation of samples. No damage was found on the surface of the ADSC sheets on the side that had been in contact with the surface of the culture dishes. In addition, when the transcriptomes of the harvested cell sheets were compared with those of monolayer cultures, no up-regulation of cell death related genes were detected. These results propose that the detachment from temperature-responsive culture dish causes no serious damage on the prepared ADSC sheet. It is also suggested that the SEM with ionic liquids is a useful and rapid method for the analysis of ADSC sheets for therapy.

Intermittent Hypoxic Therapy Inhibits Allogenic Bone-Graft Resorption by Inhibition of Osteoclastogenesis in a Mouse Model

Systemic Intermittent Hypoxic Therapy (IHT) relies on the adaptive response to hypoxic stress. We investigated allogenic bone-graft resorption in the lumbar spine in 48 mice. The mice were exposed to IHT for 1 week before surgery or 1 week after surgery and compared with controls after 1 and 4 weeks. Complete graft resorption was observed in 33-36% of the animals in the control group, but none in the preoperative IHT group. Increased bone-graft volume was demonstrated by micro-computed tomography in the preoperative IHT group after 1 week (p = 0.03) while a non-significant difference was observed after 4 weeks (p = 0.12). There were no significant differences in the postoperative IHT group. Increased concentration of immune cells was localized in the graft area, and more positive tartrate-resistant acid phosphatase (TRAP) staining was found in controls compared with IHT allogenic bone grafts. Systemic IHT resulted in a significant increase of the major osteoclast inhibitor osteoprotegerin as well as osteogenic and angiogenic regulators Tgfbr3, Fst3l, Wisp1, and Vegfd. Inflammatory cytokines and receptor activator of nuclear factor kappa-B ligand (RANKL) stimulators IL-6, IL-17a, IL-17f, and IL-23r increased after 1 and 4 weeks, and serum RANKL expression remained constant while Ccl3 and Ccl5 decreased. We conclude that the adaptive response to IHT activates numerous pathways leading to inhibition of osteoclastic activity and inhibition of allogenic bone-graft resorption.

Genomic analysis reveals a polygenic architecture of antler morphology in wild red deer (Cervus elaphus)

Sexually selected traits show large variation and rapid evolution across the animal kingdom, yet genetic variation often persists within populations despite apparent directional selection. A key step in solving this long-standing paradox is to determine the genetic architecture of sexually selected traits to understand evolutionary drivers and constraints at the genomic level. Antlers are a form of sexual weaponry in male red deer (Cervus elaphus). On the island of Rum, Scotland, males with larger antlers have increased breeding success, yet there has been no evidence of any response to selection at the genetic level. To try and understand the mechanisms underlying this observation, we investigate the genetic architecture of ten antler traits and their principal components using genomic data from >38,000 SNPs. We estimate the heritabilities and genetic correlations of the antler traits using a genomic relatedness approach. We then use genome-wide association and haplotype-based regional heritability to identify regions of the genome underlying antler morphology, and an empirical Bayes approach to estimate the underlying distributions of allele effect sizes. We show that antler morphology is highly repeatable over an individual's lifetime, heritable and has a polygenic architecture and that almost all antler traits are positively genetically correlated with some loci identified as having pleiotropic effects. Our findings suggest that a large mutational target and genetic covariances among antler traits, in part maintained by pleiotropy, are likely to contribute to the maintenance of genetic variation in antler morphology in this population.

Recent advances on signaling pathways and their inhibitors in rheumatoid arthritis

Rheumatoid arthritis (RA) is characterized by systemic synovitis leading to joint destruction in which imbalances in pro-inflammatory and anti-inflammatory cytokines promote the induction of autoimmunity. Some pro-inflammatory cytokines can trigger the signaling pathways which responsible for immune-mediated inflammation in RA, and the activated signaling pathways produce pro-inflammatory cytokines, resulting in aggravation of RA. Hence, understanding of the signaling pathways and their inhibitors might be advantageous in the development of therapeutic targets and new drugs for RA. In the current review, we summarize the signaling pathways involved in the pathogenesis of RA as well as the potential role of specific inhibitors in its management. We hope this paper may serve a reference for future studies on signaling pathways implicated in the pathogenesis of RA and benefit the treatment of RA.

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.

Early satellite cell communication creates a permissive environment for long-term muscle growth

Using in vivo muscle stem cell (satellite cell)-specific extracellular vesicle (EV) tracking, satellite cell depletion, in vitro cell culture, and single-cell RNA sequencing, we show satellite cells communicate with other cells in skeletal muscle during mechanical overload. Early satellite cell EV communication primes the muscle milieu for proper long-term extracellular matrix (ECM) deposition and is sufficient to support sustained hypertrophy in adult mice, even in the absence of fusion to muscle fibers. Satellite cells modulate chemokine gene expression across cell types within the first few days of loading, and EV delivery of miR-206 to fibrogenic cells represses Wisp1 expression required for appropriate ECM remodeling. Late-stage communication from myogenic cells during loading is widespread but may be targeted toward endothelial cells. Satellite cells coordinate adaptation by influencing the phenotype of recipient cells, which extends our understanding of their role in muscle adaptation beyond regeneration and myonuclear donation.

Wisp1 is a circulating factor that stimulates proliferation of adult mouse and human beta cells

Expanding the mass of pancreatic insulin-producing beta cells through re-activation of beta cell replication has been proposed as a therapy to prevent or delay the appearance of diabetes. Pancreatic beta cells exhibit an age-dependent decrease in their proliferative activity, partly related to changes in the systemic environment. Here we report the identification of CCN4/Wisp1 as a circulating factor more abundant in pre-weaning than in adult mice. We show that Wisp1 promotes endogenous and transplanted adult beta cell proliferation in vivo. We validate these findings using isolated mouse and human islets and find that the beta cell trophic effect of Wisp1 is dependent on Akt signaling. In summary, our study reveals the role of Wisp1 as an inducer of beta cell replication, supporting the idea that the use of young blood factors may be a useful strategy to expand adult beta cell mass.

The proliferation of pancreatic beta cells decreases with age, partly due to systemic changes. Here the authors identify Wisp1 as a circulating factor enriched in young serum that induces adult beta cell proliferation, supporting the idea that young blood factors may be useful to expand beta cell mass.

Scl-Ab reverts pro-osteoclastogenic signalling and resorption in estrogen deficient osteocytes

Background

Neutralising antibodies to sclerostin (Scl-Ab) have shown significant potential to induce bone formation and decrease bone resorption, increase strength and substantially reduce fracture risk in animal studies and clinical trials. Mechanical loading negatively regulates sclerostin expression, and sclerostin has been shown to induce RANKL synthesis in osteocytes. However, how Scl-Ab governs osteocyte regulation of osteoclast differentiation and function is not fully understood. We have recently discovered that osteoblasts and osteocytes alter osteoclastogenic signalling (RANKL/OPG) during estrogen-deficiency, and that osteoblast-induced osteoclastogenesis and resorption are exacerbated. However, it is not known whether estrogen deficient osteocytes exacerbate osteoclastogenesis. The aims of this study were to (1) establish whether osteocytes induce osteoclastogenesis and bone resorption during estrogen deficiency in vitro (2) investigate whether the sclerostin antibody can revert osteocyte-mediated osteoclastogenesis and resorption by attenuating RANKL/OPG expression.

Results

Using conditioned media and co-culture experiments we found increased osteocyte-induced osteoclastogenesis and bone resorption in estrogen deficient conditions. This is the first study to report that administration of Scl-Ab has the ability to revert osteocyte-mediated osteoclastogenesis and resorption by decreasing RANKL/OPG ratio expression and increasing WISP1 expression in estrogen deficient osteocytes.

Conclusions

This study provides an enhanced understanding of the biological changes underpinning decreases in bone resorption following Scl-Ab treatment observed in vivo by revealing that Scl-Ab can reduce pro-osteoclastogenic cell signalling between osteocytes and osteoclasts.

CCN1/Cyr61 Is Required in Osteoblasts for Responsiveness to the Anabolic Activity of PTH

CCN1/Cyr61 is a dynamically expressed matricellular protein that serves regulatory functions in multiple tissues. Previous studies from our laboratory demonstrated that CCN1 regulates bone maintenance. Using an osteoblast and osteocyte conditional knockout mouse model (Ccn1^OCN ), we found a significant decrease in trabecular and cortical bone mass in vivo, in part through suppression of Wnt signaling since the expression of the Wnt antagonist sclerostin (SOST) is increased in osteoblasts lacking CCN1. It has been established that parathyroid hormone (PTH) signaling also suppresses SOST expression in bone. We therefore investigated the interaction between CCN1 and PTH-mediated responses in this study. We find that loss of Ccn1 in osteoblasts leads to impaired responsiveness to anabolic intermittent PTH treatment in Ccn1^OCN mice in vivo and in osteoblasts from these mice in vitro. Analysis of Ccn1^OCN mice demonstrated a significant decrease in parathyroid hormone receptor-1 (PTH1R) expression in osteoblasts in vivo and in vitro. We investigated the regulatory role of a non-canonical integrin-binding domain of CCN1 because several studies indicate that specific integrins are critical to mechanotransduction, a PTH-dependent response, in bone. These data suggest that CCN1 regulates the expression of PTH1R through interaction with the αvβ3 and/or αvβ5 integrin complexes. Osteoblasts that express a mutant form of CCN1 that cannot interact with αvβ3/β5 integrin demonstrate a significant decrease in mRNA and protein expression of both PTH1R and αv integrin. Overall, these data suggest that the αvβ3/β5-binding domain of CCN1 is required to endow PTH signaling with anabolic activity in bone cells. © 2020 American Society for Bone and Mineral Research (ASBMR).

Genome-wide association study reveals genes associated with the absence of intermuscular bones in tambaqui (Colossoma macropomum)

The presence of intermuscular bones in fisheries products limits the consumption and commercialization potential of many fish species, including tambaqui (Colossoma macropomum). These bones have caused medical emergencies and are an undesirable characteristic for fish farming because their removal is labor-intensive during fish processing. Despite the difficulty in identifying genes related to the lack of intermuscular bone in diverse species of fish, the discovery of individuals lacking intermuscular bones in a Neotropical freshwater characiform fish has provided a unique opportunity to delve into the genetic mechanisms underlying the pathways of intermuscular bone formation. In this study, we carried out a GWAS among boneless and wt tambaqui populations to identify markers associated with a lack of intermuscular bone. After analyzing 11 416 SNPs in 360 individuals (12 boneless and 348 bony), we report 675 significant (P_adj  < 0.003) associations for this trait. Of those, 13 associations were located near candidate genes related to the reduction of bone mass, promotion of bone formation, inhibition of bone resorption, central control of bone remodeling, bone mineralization and other related functions. To the best of our knowledge, for the first time, we have successfully identified genes related to a lack of intermuscular bones using GWAS in a non-model species.

Gene Expression Profile and Acute Gene Expression Response to Sclerostin Inhibition in Osteogenesis Imperfecta Bone

Sclerostin antibody (SclAb) therapy has been suggested as a novel therapeutic approach toward addressing the fragility phenotypic of osteogenesis imperfecta (OI). Observations of cellular and transcriptional responses to SclAb in OI have been limited to mouse models of the disorder, leaving a paucity of data on the human OI osteoblastic cellular response to the treatment. Here, we explore factors associated with response to SclAb therapy in vitro and in a novel xenograft model using OI bone tissue derived from pediatric patients. Bone isolates (approximately 2 mm3) from OI patients (OI type III, type III/IV, and type IV, n = 7; non-OI control, n = 5) were collected to media, randomly assigned to an untreated (UN), low-dose SclAb (TRL, 2.5 μg/mL), or high-dose SclAb (TRH, 25 μg/mL) group, and maintained in vitro at 37°C. Treatment occurred on days 2 and 4 and was removed on day 5 for TaqMan qPCR analysis of genes related to the Wnt pathway. A subset of bone was implanted s.c. into an athymic mouse, representing our xenograft model, and treated (25 mg/kg s.c. 2×/week for 2/4 weeks). Implanted OI bone was evaluated using μCT and histomorphometry. Expression of Wnt/Wnt-related targets varied among untreated OI bone isolates. When treated with SclAb, OI bone showed an upregulation in osteoblast and osteoblast progenitor markers, which was heterogeneous across tissue. Interestingly, the greatest magnitude of response generally corresponded to samples with low untreated expression of progenitor markers. Conversely, samples with high untreated expression of these markers showed a lower response to treatment. in vivo implanted OI bone showed a bone-forming response to SclAb via μCT, which was corroborated by histomorphometry. SclAb induced downstream Wnt targets WISP1 and TWIST1, and elicited a compensatory response in Wnt inhibitors SOST and DKK1 in OI bone with the greatest magnitude from OI cortical bone. Understanding patients' genetic, cellular, and morphological bone phenotypes may play an important role in predicting treatment response. This information may aid in clinical decision-making for pharmacological interventions designed to address fragility in OI. © 2020 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.

Endogenous CCN family member WISP1 inhibits trauma-induced heterotopic ossification

Heterotopic ossification (HO) is defined as abnormal differentiation of local stromal cells of mesenchymal origin, resulting in pathologic cartilage and bone matrix deposition. Cyr61, CTGF, Nov (CCN) family members are matricellular proteins that have diverse regulatory functions on cell proliferation and differentiation, including the regulation of chondrogenesis. However, little is known regarding CCN family member expression or function in HO. Here, a combination of bulk and single-cell RNA sequencing defined the dynamic temporospatial pattern of CCN family member induction within a mouse model of trauma-induced HO. Among CCN family proteins, Wisp1 (also known as Ccn4) was most upregulated during the evolution of HO, and Wisp1 expression corresponded with chondrogenic gene profile. Immunohistochemistry confirmed WISP1 expression across traumatic and genetic HO mouse models as well as in human HO samples. Transgenic Wisp1LacZ/LacZ knockin animals showed an increase in endochondral ossification in HO after trauma. Finally, the transcriptome of Wisp1-null tenocytes revealed enrichment in signaling pathways, such as the STAT3 and PCP signaling pathways, that may explain increased HO in the context of Wisp1 deficiency. In sum, CCN family members, and in particular Wisp1, are spatiotemporally associated with and negatively regulate trauma-induced HO formation.

The Effects of microRNA-515-5p on the Toll-Like Receptor 4 (TLR4)/JNK Signaling Pathway and WNT1-Inducible-Signaling Pathway Protein 1 (WISP-1) Expression in Rheumatoid Arthritis Fibroblast-Like Synovial (RAFLS) Cells Following Treatment with Receptor Activator of Nuclear Factor-kappa-B Ligand (RANKL)

BACKGROUND This study aimed to investigate the effects of microRNA-515-5p (miR-515-5p) on the expression of the WNT1-inducible-signaling pathway protein 1 (WISP-1) gene in rheumatoid arthritis fibroblast-like synovial (RAFLS) cells following treatment with the receptor activator of nuclear factor-kappa-B ligand (RANKL). MATERIAL AND METHODS RAFLS cells were cultured in vitro and were divided into six study groups: a normal control group; a miR-515-5p mimic group; a miR-515-5p inhibitor group; a RANKL (50 ng/ml) treatment group; a miR-515-5p mimic+RANKL treatment group; and a miR-515-5p inhibitor+RANKL treatment group. The luciferase assay was used to determine the effects of miR-515-5p on the WISP1 expression. Cell proliferation, cell apoptosis, the cell cycle, and protein expression were determined using the Cell Counting Kit-8 (CCK-8) assay, flow cytometry, Western blot, and real-time polymerase chain reaction (RT-PCR). RESULTS The luciferase assay showed that the effects of miR-515-on the 3'-UTR of WISP1 inhibited the gene expression. The miR-515-5p mimics promoted cell proliferation, reduced apoptosis, and promoted the cell cycle. The miR-515-5p mimics reduced, the expression of TLR4, WISP1, and JNK at the mRNA level, while the miR-515-5p inhibitor promoted the expression of TLR4, WISP1, and JNK. Both the miR-515-5p inhibitor and mimic promoted the phosphorylation of AKT in RAFLS cells treated with or without RANKL compared with the control, and the miR-515-5p inhibitor promoted the phosphorylation of JNK in the RAFLS cells. CONCLUSIONS In RAFLS cells, miR-515-5p inhibited the expression of the WISP1 gene, and treatment with RANKL inhibited the TLR4/JNK signaling pathway.

The Matrix Revolution: Matricellular Proteins and Restructuring of the Cancer Microenvironment

The extracellular matrix (ECM) surrounding cells is indispensable for regulating their behavior. The dynamics of ECM signaling are tightly controlled throughout growth and development. During tissue remodeling, matricellular proteins (MCP) are secreted into the ECM. These factors do not serve classical structural roles, but rather regulate matrix proteins and cell-matrix interactions to influence normal cellular functions. In the tumor microenvironment, it is becoming increasingly clear that aberrantly expressed MCPs can support multiple hallmarks of carcinogenesis by interacting with various cellular components that are coupled to an array of downstream signals. Moreover, MCPs also reorganize the biomechanical properties of the ECM to accommodate metastasis and tumor colonization. This realization is stimulating new research on MCPs as reliable and accessible biomarkers in cancer, as well as effective and selective therapeutic targets.

Antiresorptive and anabolic agents in the prevention and reversal of bone fragility

Bone volume, microstructure and its material composition are maintained by bone remodelling, a cellular activity carried out by bone multicellular units (BMUs). BMUs are focally transient teams of osteoclasts and osteoblasts that respectively resorb a volume of old bone and then deposit an equal volume of new bone at the same location. Around the time of menopause, bone remodelling becomes unbalanced and rapid, and an increased number of BMUs deposit less bone than they resorb, resulting in bone loss, a reduction in bone volume and microstructural deterioration. Cortices become porous and thin, and trabeculae become thin, perforated and disconnected, causing bone fragility. Antiresorptive agents reduce fracture risk by reducing the rate of bone remodelling so that fewer BMUs are available to remodel bone. Bone fragility is not abolished by these drugs because existing microstructural deterioration is not reversed, unsuppressed remodelling continues producing microstructural deterioration and unremodelled bone that becomes more mineralized can become brittle. Anabolic agents reduce fracture risk by stimulating new bone formation, which partly restores bone volume and microstructure. To guide fracture prevention, this Review provides an overview of the structural basis of bone fragility, the mechanisms of remodelling and how anabolic and antiresorptive agents target remodelling defects.

CFTR deletion affects mouse osteoblasts in a gender-specific manner

Advancements in research and care have contributed to increase life expectancy of individuals with cystic fibrosis (CF). With increasing age comes a greater likelihood of developing CF bone disease, a comorbidity characterized by a low bone mass and impaired bone quality, which displays gender differences in severity. However, pathophysiological mechanisms underlying this gender difference have never been thoroughly investigated. We used bone marrow-derived osteoblasts and osteoclasts from Cftr^+/+ and Cftr^-/- mice to examine whether the impact of CF transmembrane conductance regulator (CFTR) deletion on cellular differentiation and functions differed between genders. To determine whether in vitro findings translated into in vivo observations, we used imaging techniques and three-point bending testing. In vitro studies revealed no osteoclast-autonomous defect but impairment of osteoblast differentiation and functions and aberrant responses to various stimuli in cells isolated from Cftr^-/- females only. Compared with wild-type controls, knockout mice exhibited a trabecular osteopenic phenotype that was more pronounced in Cftr^-/- males than Cftr^-/- females. Bone strength was reduced to a similar extent in knockout mice of both genders. In conclusion, we find a trabecular bone phenotype in Cftr^-/- mice that was slightly more pronounced in males than females, which is reminiscent of the situation found in patients. However, at the osteoblast level, the pathophysiological mechanisms underlying this phenotype differ between males and females, which may underlie gender differences in the way bone marrow-derived osteoblasts behave in absence of CFTR.

Reduced Bone Modeling and Unbalanced Bone Remodeling: Targets for Antiresorptive and Anabolic Therapy

Bone loss during advancing age is the net result of reduced modeling-based bone formation upon the outer (periosteal) envelope and unbalanced remodeling by basic multicellular units (BMUs) upon the three (intracortical, endocortical, and trabecular) components of the inner (endosteal) bone envelope. Each BMU deposits less bone than resorbed, reducing total bone volume and deteriorating the microstructure of the diminished residual bone volume.Antiresorptive agents like bisphosphonates reduce, but do not abolish, the rate of bone remodeling - fewer BMUs remodel, "turn over," the volume of bone. Residual unbalanced remodeling continues to slowly reduce total bone volume and deteriorate bone microstructure. By contrast, denosumab virtually abolishes remodeling so the decrease in bone volume and the deterioration in microstructure cease. The less remodeled matrix remains, leaving more time to complete the slow process of secondary mineralization which reduces the heterogeneity of matrix mineralization and allows it to become glycosylated, changes that may make the smaller and microstructurally deteriorated bone volume more brittle. Neither class of antiresorptive restores bone volume or its microstructure, despite increases in bone mineral density misleadingly suggesting otherwise. Nevertheless, these agents reduce vertebral and hip fractures by 50-60% but only reduce nonvertebral fractures by 20-30%.Restoring bone volume, microstructure, and material composition, "curing" bone fragility, may be partly achieved using anabolic therapy. Teriparatide, and probably abaloparatide, produce mainly remodeling-based bone formation by acting on BMUs existing in their resorption, reversal, or formation phase at the time of treatment and by promoting bone formation in newly initiated BMUs. Romosozumab produces modeling-based bone formation almost exclusively and decreases the surface extent of bone resorption. All three anabolic agents reduce vertebral fracture risk relative to untreated controls; parathyroid hormone 1-34 and romosozumab reduce vertebral fracture risk more greatly than risedronate or alendronate, respectively. Evidence for nonvertebral or hip fracture risk reduction relative to untreated or antiresorptive-treated controls is lacking or inconsistent. Only one study suggests sequential romosozumab followed by alendronate reduces vertebral, nonvertebral, and hip fracture risk compared to continuous alendronate alone. Whether combined antiresorptive and anabolic therapy result in superior fracture risk reduction than monotherapy is untested.

Fibro-Adipogenic Progenitors Cross-Talk in Skeletal Muscle: The Social Network

Skeletal muscle is composed of a large and heterogeneous assortment of cell populations that interact with each other to maintain muscle homeostasis and orchestrate regeneration. Although satellite cells (SCs) – which are muscle stem cells – are the protagonists of functional muscle repair following damage, several other cells such as inflammatory, vascular, and mesenchymal cells coordinate muscle regeneration in a finely tuned process. Fibro–adipogenic progenitors (FAPs) are a muscle interstitial mesenchymal cell population, which supports SCs differentiation during tissue regeneration. During the first days following muscle injury FAPs undergo massive expansion, which is followed by their macrophage-mediated clearance and the re-establishment of their steady-state pool. It is during this critical time window that FAPs, together with the other cellular components of the muscle stem cell niche, establish a dynamic network of interactions that culminate in muscle repair. A number of different molecules have been recently identified as important mediators of this cross-talk, and its alteration has been associated with different muscle pathologies. In this review, we will focus on the soluble factors that regulate FAPs activity, highlighting their roles in orchestrating the inter-cellular interactions between FAPs and the other cell populations that participate in muscle regeneration.

The tumor cell-secreted matricellular protein WISP1 drives pro-metastatic collagen linearization

Collagen linearization is a hallmark of aggressive tumors and a key pathogenic event that promotes cancer cell invasion and metastasis. Cell-generated mechanical tension has been proposed to contribute to collagen linearization in tumors, but it is unknown whether other mechanisms play prominent roles in this process. Here, we show that the secretome of cancer cells is by itself able to induce collagen linearization independently of cell-generated mechanical forces. Among the tumor cell-secreted factors, we find a key role in this process for the matricellular protein WISP1 (CCN4). Specifically, WISP1 directly binds to type I collagen to promote its linearization in vitro (in the absence of cells) and in vivo in tumors. Consequently, WISP1-induced type I collagen linearization facilitates tumor cell invasion and promotes spontaneous breast cancer metastasis, without significantly affecting gene expression. Furthermore, higher WISP1 expression in tumors from cancer patients correlates with faster progression to metastatic disease and poor prognosis. Altogether, these findings reveal a conceptually novel mechanism whereby pro-metastatic collagen linearization critically depends on a cancer cell-secreted factor.

WNT1-inducible signaling pathway protein 1 (WISP1/CCN4) stimulates melanoma invasion and metastasis by promoting the epithelial-mesenchymal transition

Besides intrinsic changes, malignant cells also release soluble signals that reshape their microenvironment. Among these signals is WNT1-inducible signaling pathway protein 1 (WISP1), a secreted matricellular protein whose expression is elevated in several cancers, including melanoma, and is associated with reduced survival of patients diagnosed with primary melanoma. Here, we found that WISP1 knockout increases cell proliferation and represses wound healing, migration, and invasion of mouse and human melanoma cells in multiple in vitro assays. Metastasis assays revealed that WISP1 knockout represses tumor metastasis of B16F10 and YUMM1.7 melanoma cells in both C57BL/6Ncrl and NOD-scid IL2Rγ^null (NSG) mice. WT B16F10 cells having an invasion phenotype in a transwell assay possessed a gene expression signature similar to that observed in the epithelial-mesenchymal transition (EMT), including E-cadherin repression and fibronectin and N-cadherin induction. Upon WISP1 knockout, expression of these EMT signature genes went in the opposite direction in both mouse and human cell lines, and EMT-associated gene expression was restored upon exposure to media containing WISP1 or to recombinant WISP1 protein. In vivo, Wisp1 knockout-associated metastasis repression was reversed by the reintroduction of either WISP1 or snail family transcriptional repressor 1 (SNAI1). Experiments testing EMT gene activation and inhibition with recombinant WISP1 or kinase inhibitors in B16F10 and YUMM1.7 cells suggested that WISP1 activates AKT Ser/Thr kinase and that MEK/ERK signaling pathways shift melanoma cells from proliferation to invasion. Our results indicate that WISP1 present within the tumor microenvironment stimulates melanoma invasion and metastasis by promoting an EMT-like process.

Aging Disrupts Muscle Stem Cell Function by Impairing Matricellular WISP1 Secretion from Fibro-Adipogenic Progenitors

Research on age-related regenerative failure of skeletal muscle has extensively focused on the phenotypes of muscle stem cells (MuSCs). In contrast, the impact of aging on regulatory cells in the MuSC niche remains largely unexplored. Here, we demonstrate that aging impairs the function of mouse fibro-adipogenic progenitors (FAPs) and thereby indirectly affects the myogenic potential of MuSCs. Using transcriptomic profiling, we identify WNT1 Inducible Signaling Pathway Protein 1 (WISP1) as a FAP-derived matricellular signal that is lost during aging. WISP1 is required for efficient muscle regeneration and controls the expansion and asymmetric commitment of MuSCs through Akt signaling. Transplantation of young FAPs or systemic treatment with WISP1 restores the myogenic capacity of MuSCs in aged mice and rescues skeletal muscle regeneration. Our work establishes that loss of WISP1 from FAPs contributes to MuSC dysfunction in aged skeletal muscles and demonstrates that this mechanism can be targeted to rejuvenate myogenesis.

LncRNA FOXC2-AS1 protects cardiomyocytes from doxorubicin-induced cardiotoxicity through activation of WNT1-inducible signaling pathway protein-1

Doxorubicin (Dox) is an anthracycline antibiotic that has been used to treat different cancers. Dox-induced cardiotoxicity is common in clinical practice, while its mechanism is unknown. It has been proved that lncRNA FOXC2-AS1 may promote doxorubicin resistance and WNT1-inducible signaling pathway protein-1 (WISP1) blocks doxorubicin-induced cardiomyocyte death. Our study aimed to investigate the involvement of lncRNA FOXC2-AS1 and WISP1 in doxorubicin-induced cardiotoxicity and to explore their interactions. In our study we observed that FOXC2-AS1 and WISP1 mRNA were downregulated in heart tissues of mice with Dox-induced cardiotoxicity. FOXC2-AS1 and WISP1 mRNA expression were positively correlated in mice with Dox-induced cardiotoxicity but not in healthy mice. Overexpression of FOXC2-AS1 promoted to viability of mice cardiomyocytes under Dox treatment and also increased the expression level of WISP1. In contrast, WISP1 overexpression showed no significant effect on FOXC2-AS1. We therefore conclude that lncRNA FOXC2-AS1 may upregulate WISP1 to protect cardiomyocytes from doxorubicin-induced cardiotoxicity.

Secretome proteins regulate comparative osteogenic and adipogenic potential in bone marrow and dental stem cells

INTRODUCTION

Dental stem cells (DMSC) have been studied extensively since their early discovery. However, the data regarding osteogenic potential of DMSC with other cell types is sparse and the secretome proteins underlying these differences have not been explored. In this study, we have compared the osteogenic and adipogenic potential of DMSC with Bone Marrow Stem cells (BMSC) and reported the contribution of secretome proteins in controlling their differentiation.

METHODS

Osteogenic potential of these stem cells was compared by mineralization assay, alkaline phosphatase (ALP) assay, immunofluorescence of dentine sialo phosphoprotein (DSPP) & qPCR for osteogenic genes. Adipogenic potential was compared by Oil Red O staining and qPCR for PPAR-γ, leptin & adipsin. Proteomic analysis of secretome was performed by employing WATERS nano Lc-MS/MS system.

RESULTS

We observed a higher osteogenic potential in DMSC, especially dental pulp stem cells (DPSC) as compared to BMSC population but adipogenic potential was found to be better in BMSC as compared to DMSC. Deeper investigations into secretome of these cells by Lc-MS/MS revealed the presence of proteins pertaining to osteogenic and adipogenic lineage. Presence of some important proteins regulating osteogenic (DSPP, BMP7, DDR2, USP9X) and adipogenic differentiation (NCOA2, PEG10, LPA) in secretome of BMSC and DMSC reflected the role of paracrine factors during differentiation.

CONCLUSION

Our study provides first evidence regarding regulation of osteogenic/adipogenic potential by secretome proteins in DMSC and BMSC. DMSC especially DPSC and its secretome show an inherent tendency for higher osteogenic differentiation and lower adipogenic differentiation, these may be potential candidates for effective future therapy in osteoporosis where disturbance of osteocyte/adipocyte homeostasis is reported.

WISP-1 drives bone formation at the expense of fat formation in human perivascular stem cells

The vascular wall within adipose tissue is a source of mesenchymal progenitors, referred to as perivascular stem/stromal cells (PSC). PSC are isolated via fluorescence activated cell sorting (FACS), and defined as a bipartite population of pericytes and adventitial progenitor cells (APCs). Those factors that promote the differentiation of PSC into bone or fat cell types are not well understood. Here, we observed high expression of WISP-1 among human PSC in vivo, after purification, and upon transplantation in a bone defect. Next, modulation of WISP-1 expression was performed, using WISP-1 overexpression, WISP-1 protein, or WISP-1 siRNA. Results demonstrated that WISP-1 is expressed in the perivascular niche, and high expression is maintained after purification of PSC, and upon transplantation in a bone microenvironment. In vitro studies demonstrate that WISP-1 has pro-osteogenic/anti-adipocytic effects in human PSC, and that regulation of BMP signaling activity may underlie these effects. In summary, our results demonstrate the importance of the matricellular protein WISP-1 in regulation of the differentiation of human stem cell types within the perivascular niche. WISP-1 signaling upregulation may be of future benefit in cell therapy mediated bone tissue engineering, for the healing of bone defects or other orthopaedic applications.

The novel adipokine WISP1 associates with insulin resistance and impairs insulin action in human myotubes and mouse hepatocytes

AIMS/HYPOTHESIS

Wingless-type (Wnt) inducible signalling pathway protein-1 (WISP1) has been recently identified as a proinflammatory adipokine. We examined whether WISP1 expression and circulating levels are altered in type 2 diabetes and whether WISP1 affects insulin signalling in muscle cells and hepatocytes.

METHODS

Serum and visceral adipose tissue (VAT) biopsies, for analysis of circulating WISP1 levels by ELISA and WISP1 mRNA expression by real-time quantitative RT-PCR, were collected from normal-weight men (control group, n = 33) and obese men with (n = 46) and without type 2 diabetes (n = 56) undergoing surgery. Following incubation of primary human skeletal muscle cells (hSkMCs) and murine AML12 hepatocytes with WISP1 and insulin, insulin signalling was analysed by western blotting. The effect of WISP1 on insulin-stimulated glycogen synthesis and gluconeogenesis was investigated in hSkMCs and murine hepatocytes, respectively.

RESULTS

Circulating WISP1 levels were higher in obese men (independent of diabetes status) than in normal-weight men (mean [95% CI]: 70.8 [55.2, 86.4] ng/l vs 42.6 [28.5, 56.6] ng/l, respectively; p < 0.05). VAT WISP1 expression was 1.9-fold higher in obese men vs normal-weight men (p < 0.05). Circulating WISP1 levels were positively associated with blood glucose in the OGTT and circulating haem oxygenase-1 and negatively associated with adiponectin levels. In hSkMCs and AML12 hepatocytes, recombinant WISP1 impaired insulin action by inhibiting phosphorylation of insulin receptor, Akt and its substrates glycogen synthase kinase 3β, FOXO1 and p70S6 kinase, and inhibiting insulin-stimulated glycogen synthesis and suppression of gluconeogenic genes.

CONCLUSIONS/INTERPRETATION

Circulating WISP1 levels and WISP1 expression in VAT are increased in obesity independent of glycaemic status. Furthermore, WISP1 impaired insulin signalling in muscle and liver cells.

CYR61/CCN1 Regulates Sclerostin Levels and Bone Maintenance

CYR61/CCN1 is a matricellular protein that resides in the extracellular matrix, but serves regulatory rather than structural roles. CYR61/CCN1 is found in mineralized tissues and has been shown to influence bone healing in vivo and osteogenic differentiation in vitro. In this study we generated Cyr61 bone-specific knockout mice to examine the physiological role of CYR61/CCN1 in bone development and maintenance in vivo. Extensive analysis of Cyr61 conditional knockout mice showed a significant decrease in both trabecular and cortical bone mass as compared to WT littermates. Our data suggest that CYR61/CCN1 exerts its effects on mature osteoblast/osteocyte function to modulate bone mass. Specifically, changes were observed in osteocyte/osteoblast expression of RankL, VegfA, and Sost. The increase in RankL expression was correlated with a significant increase in osteoclast number; decreased VegfA expression was correlated with a significant decrease in bone vasculature; increased Sost expression was associated with decreased Wnt signaling, as revealed by decreased Axin2 expression and increased adiposity in the bone marrow. Although the decreased number of vascular elements in bone likely contributes to the low bone mass phenotype in Cyr61 conditional knockout mice, this cannot explain the observed increase in osteoclasts and the decrease in Wnt signaling. We conducted in vitro assays using UMR-106 osteosarcoma cells to explore the role CYR61/CCN1 plays in modulating Sost mRNA and protein expression in osteocytes and osteoblasts. Overexpression of CYR61/CCN1 can suppress Sost expression in both control and Cyr61 knockout cells, and blocking Sost with siRNA can rescue Wnt responsiveness in Cyr61 knockout cells in vitro. Overall, our data suggest that CYR61/CCN1 modulates mature osteoblast and osteocyte function to regulate bone mass through angiogenic effects as well as by modulating Wnt signaling, at least in part through the Wnt antagonist Sost. © 2018 American Society for Bone and Mineral Research.

Evaluation of WISP1 as a candidate gene for bone mineral density in the Old Order Amish

Wnt1-inducible signaling pathway protein-1 (WISP1) is a novel target of the Wnt pathway for modulating osteogenesis and improving bone strength. However, it is not clear if genetic variants in the WISP1 region are associated with bone mineral density (BMD) in human. The aim of this study is to investigate the role of genetic variation in WISP1 gene as a determinant of BMD in 1,510 Old Order Amish (OOA). We performed regional association analysis of 58 tag variants within 5 kb upstream and downstream to WISP1 with BMD and found 5 variants that were associated with BMD at multiple skeletal sites (P values from 2.89 × 10⁻⁶ to 1.62 × 10⁻²), with some significant associations even after adjustment for multiple comparisons. To replicate these results in an independent dataset, we performed a look-up of BMD associations with these variants in European ancestry subjects from the large GEFOS Consortium and observed the nominal associations of two of these variants with BMD (P values: 0.031 to 0.048). In conclusion, we have demonstrated that genetic variants surrounding WISP1 are associated with BMD at multiple skeletal sites in the OOA, thus influencing osteoporosis risk. These results support a role for the WISP1 gene on influencing variation in BMD.

Secreted Clusterin protein inhibits osteoblast differentiation of bone marrow mesenchymal stem cells by suppressing ERK1/2 signaling pathway

Secreted Clusterin (sCLU, also known as Apolipoprotein J) is an anti-apoptotic glycoprotein involved in the regulation of cell proliferation, lipid transport, extracellular tissue remodeling and apoptosis. sCLU is expressed and secreted by mouse bone marrow-derived skeletal (stromal or mesenchymal) stem cells (mBMSCs), but its functional role in MSC biology is not known. In this study, we demonstrated that Clusterin mRNA expression and protein secretion in conditioned medium increased during adipocyte differentiation and decreased during osteoblast differentiation of mBMSCs. Treatment of mBMSC cultures with recombinant sCLU protein increased cell proliferation and exerted an inhibitory effect on the osteoblast differentiation while stimulated adipocyte differentiation in a dose-dependent manner. siRNA-mediated silencing of Clu expression in mBMSCs reduced adipocyte differentiation and stimulated osteoblast differentiation of mBMSCs. Furthermore, the inhibitory effect of sCLU on the osteoblast differentiation of mBMSCs was mediated by the suppression of extracellular signal-regulated kinase (ERK1/2) phosphorylation. In conclusion, we identified sCLU as a regulator of mBMSCs lineage commitment to osteoblasts versus adipocytes through a mechanism mediated by ERK1/2 signaling. Inhibiting sCLU is a possible therapeutic approach for enhancing osteoblast differentiation and consequently bone formation.

Osteoblast-secreted WISP-1 promotes adherence of prostate cancer cells to bone via the VCAM-1/integrin α4β1 system

Bone metastasis is a frequent occurrence in prostate cancer (PCa) that is associated with severe complications such as fracture, bone pain and hypercalcemia. The cross-talk between metastatic cancer cells and bone is critical to the development and progression of bone metastases. In our previous data, we have described how the involvement of the Wnt-induced secreted protein-1/vascular cell adhesion molecule-1 (WISP-1/VCAM-1) system in this tumor-bone interaction contributes to human PCa cell motility. In this study, we found that WISP-1 regulates bone mineralization by inducing bone morphogenetic protein-2 (BMP2), BMP4 and osteopontin (OPN) expression in osteoblasts. We also found that WISP-1 inhibited RANKL-dependent osteoclastogenesis. Moreover, osteoblast-derived WISP-1 enhanced VCAM-1 expression in PCa cells and subsequently promoted the adherence of cancer cells to osteoblasts. Furthermore, endothelin-1 (ET-1) expression in PCa cells was regulated by osteoblast-derived WISP-1, which promoted integrin α4β1 expression in osteoblasts via the MAPK pathway. Pretreatment of PCa cells with VCAM-1 antibody or osteoblasts with integrin α4β1 antibody attenuated the adherence of PCa cells to osteoblasts, suggesting that integrin α4β1 serves as a ligand that captures VCAM-1⁺ metastatic tumor cells adhering to osteoblasts. Our findings reveal that osteoblast-derived WISP-1 plays a key role in regulating the adhesion of PCa cells to osteoblasts via the VCAM-1/integrin α4β1 system. Osteoblast-derived WISP-1 is a promising target for the prevention and inhibition of PCa-bone interaction.

Gene expression analysis of human adipose tissue-derived stem cells during the initial steps of in vitro osteogenesis

Mesenchymal stem cells (MSCs) have been widely studied with regard to their potential use in cell therapy protocols and regenerative medicine. However, a better comprehension about the factors and molecular mechanisms driving cell differentiation is now mandatory to improve our chance to manipulate MSC behavior and to benefit future applications. In this work, we aimed to study gene regulatory networks at an early step of osteogenic differentiation. Therefore, we analyzed both the total mRNA and the mRNA fraction associated with polysomes on human adipose tissue-derived stem cells (hASCs) at 24 h of osteogenesis induction. The RNA-seq results evidenced that hASC fate is not compromised with osteogenesis at this time and that 21 days of continuous cell culture stimuli are necessary for full osteogenic differentiation of hASCs. Furthermore, early stages of osteogenesis induction involved gene regulation that was linked to the management of cell behavior in culture, such as the control of cell adhesion and proliferation. In conclusion, although discrete initial gene regulation related to osteogenesis occur, the first 24 h of induction is not sufficient to trigger and drive in vitro osteogenic differentiation of hASCs.