The inflammatory speech of fibroblasts.

Activation of fibroblasts is a key event during normal tissue repair after injury and the dysregulated repair processes that result in organ fibrosis. To most researchers, fibroblasts are rather unremarkable spindle-shaped cells embedded in the fibrous collagen matrix of connective tissues and/or deemed useful to perform mechanistic studies with adherent cells in culture. For more than a century, fibroblasts escaped thorough classification due to the lack of specific markers and were treated as the leftovers after all other cells have been identified from a tissue sample. With novel cell lineage tracing and single cell transcriptomics tools, bona fide fibroblasts emerge as only one heterogeneous sub-population of a much larger group of partly overlapping cell types, including mesenchymal stromal cells, fibro-adipogenic progenitor cells, pericytes, and/or perivascular cells. All these cells are activated to contribute to tissue repair after injury and/or chronic inflammation. "Activation" can entail various functions, such as enhanced proliferation, migration, instruction of inflammatory cells, secretion of extracellular matrix proteins and organizing enzymes, and acquisition of a contractile myofibroblast phenotype. We provide our view on the fibroblastic cell types and activation states playing a role during physiological and pathological repair and their crosstalk with inflammatory macrophages. Inflammation and fibrosis of the articular synovium during rheumatoid arthritis and osteoarthritis are used as specific examples to discuss inflammatory fibroblast phenotypes. Ultimately, delineating the precursors and functional roles of activated fibroblastic cells will contribute to better and more specific intervention strategies to treat fibroproliferative and fibrocontractive disorders.

Association of synovial fluid and urinary C2C-HUSA levels with surgical outcomes post-total knee arthroplasty.

OBJECTIVES: After total knee arthroplasty (TKA), ∼30% of knee osteoarthritis (KOA) patients show little symptomatic improvement. Earlier studies have correlated urinary (u) type 2 collagen C terminal cleavage peptide assay (C2C-HUSA), which detects a fragment of cartilage collagen breakdown, with KOA progression. This study determines whether C2C levels in urine, synovial fluid, or their ratio, are associated with post-surgical outcomes. METHODS: From a large sample of 489 subjects, diagnosed with primary KOA undergoing TKA, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain and function scores were collected at baseline (time of surgery) and one-year post-TKA. Baseline urine (u) and synovial fluid (sf) were analysed using the IBEX-C2C-HUSA assay, with higher values indicating higher amounts of cartilage degradation. For urine, results were normalised to creatinine. Furthermore, subjects' changes in WOMAC scores were categorised based on percent reduction in pain or improvement in function, compared to baseline, such that >66.7%, >33.3 to ≤66.7%, and ≤33.3% denoted "strong", "moderate" and "mild/worse" responses, respectively. Associations of individual biofluid C2C-HUSA levels, or their ratio, with change in WOMAC pain and function scores up to one-year post-TKA, or category of change, were analysed by linear, logistic, or cumulative odds models. RESULTS: Higher baseline uC2C-HUSA levels or a lower ratio of baseline sfC2C-HUSA to uC2C-HUSA were associated with improvements in WOMAC pain by linear multivariable modelling [odds ratio -0.40 (95% confidence interval -0.76, -0.05) p = 0.03; 0.36 (0.01, 0.71), p = 0.04, respectively], while sfC2C-HUSA alone was not. However, lower ratios of sfC2C-HUSA to uC2C-HUSA were associated with improvements in WOMAC function [1.37 (0.18, 2.55), p = 0.02], while sfC2C-HUSA and uC2C-HUSA alone were not. Lower ratios of sfC2C-HUSA to uC2C-HUSA were also associated with an increased likelihood of a subject being categorised in a group where TKA was beneficial in both univariable [pain, 0.81 (0.68, 0.96), p = 0.02; function, 0.92 (0.85, 0.99), p = 0.035] and multivariable [pain, 0.81 (0.68, 0.97) p = 0.02; function, 0.92 (0.85, 1.00), p = 0.043] ordinal modelling, while sfC2C-HUSA and uC2C-HUSA alone were not. CONCLUSIONS: Overall, ratios of baseline sfC2C-HUSA to uC2C-HUSA, and baseline uC2C-HUSA, may play an important role in studying post-TKA surgical outcomes.

Three decades of advancements in osteoarthritis research: insights from transcriptomic, proteomic, and metabolomic studies.

OBJECTIVE: Osteoarthritis (OA) is a complex disease involving contributions from both local joint tissues and systemic sources. Patient characteristics, encompassing sociodemographic and clinical variables, are intricately linked with OA rendering its understanding challenging. Technological advancements have allowed for a comprehensive analysis of transcripts, proteomes and metabolomes in OA tissues/fluids through omic analyses. The objective of this review is to highlight the advancements achieved by omic studies in enhancing our understanding of OA pathogenesis over the last three decades. DESIGN: We conducted an extensive literature search focusing on transcriptomics, proteomics and metabolomics within the context of OA. Specifically, we explore how these technologies have identified individual transcripts, proteins, and metabolites, as well as distinctive endotype signatures from various body tissues or fluids of OA patients, including insights at the single-cell level, to advance our understanding of this highly complex disease. RESULTS: Omic studies reveal the description of numerous individual molecules and molecular patterns within OA-associated tissues and fluids. This includes the identification of specific cell (sub)types and associated pathways that contribute to disease mechanisms. However, there remains a necessity to further advance these technologies to delineate the spatial organization of cellular subtypes and molecular patterns within OA-afflicted tissues. CONCLUSIONS: Leveraging a multi-omics approach that integrates datasets from diverse molecular detection technologies, combined with patients' clinical and sociodemographic features, and molecular and regulatory networks, holds promise for identifying unique patient endophenotypes. This holistic approach can illuminate the heterogeneity among OA patients and, in turn, facilitate the development of tailored therapeutic interventions.

Early microRNA and metabolite changes after anterior cruciate ligament reconstruction surgery.

OBJECTIVES: Anterior cruciate ligament (ACL) reconstruction after injury does not prevent post-traumatic osteoarthritis (PTOA). Circulating microRNA (miRNA) and metabolite changes emerging shortly after ACL injury and reconstruction remain insufficiently defined, potentially harbouring early cues contributing to PTOA evolution. Moreover, their differential expression between females and males also may influence PTOA's natural trajectory. This study aims to determine alterations in plasma miRNA and metabolite levels in the early stages following ACL reconstruction and between females and males. METHODS: A cohort of 43 ACL reconstruction patients was examined. Plasma was obtained at baseline, 2 weeks, and 6 weeks post-surgery (129 biospecimens in total). High-throughput miRNA sequencing and metabolomics were conducted. Differentially expressed miRNAs and metabolites were identified using negative binomial and linear regression models, respectively. Associations between miRNAs and metabolites were explored using time and sex as co-variants, (pre-surgery versus 2 and 6 weeks post-surgery). Using computational biology, miRNA-metabolite-gene interaction and pathway analyses were performed. RESULTS: Levels of 46 miRNAs were increased at 2 weeks post-surgery compared to pre-surgery (baseline) using miRNA sequencing. Levels of 13 metabolites were significantly increased while levels of 6 metabolites were significantly decreased at 2 weeks compared to baseline using metabolomics. Hsa-miR-145-5p levels were increased in female subjects at both 2 weeks (log2-fold-change 0.71, 95%CI 0.22,1.20) and 6 weeks (log2-fold-change 0.75, 95%CI 0.07,1.43) post-surgery compared to males. In addition, hsa-miR-497-5p showed increased levels in females at 2 weeks (log2-fold-change 0.77, 95%CI 0.06,1.48) and hsa-miR-143-5p at 6 weeks (log2-fold-change 0.83, 95%CI 0.07,1.59). Five metabolites were decreased at 2 weeks post-surgery in females compared to males: L-leucine (-1.44, 95%CI -1.75,-1.13), g-guanidinobutyrate (-1.27, 95%CI 1.54,-0.99), creatinine (-1.17, 95%CI -1.44,-0.90), 2-methylbutyrylcarnitine (-1.76, 95%CI -2.17,-1.35), and leu-pro (-1.13, 95%CI -1.44,-0.83). MiRNA-metabolite-gene interaction analysis revealed key signalling pathways based on post-surgical time-point and in females versus males. CONCLUSION: MiRNA and metabolite profiles were modified by time and by sex early after ACL reconstruction surgery, which could influence surgical response and ultimately risk of developing PTOA.

Evolution and advancements in genomics and epigenomics in OA research: How far we have come.

OBJECTIVE: Osteoarthritis (OA) is the most prevalent musculoskeletal disease affecting articulating joint tissues, resulting in local and systemic changes that contribute to increased pain and reduced function. Diverse technological advancements have culminated in the advent of high throughput "omic" technologies, enabling identification of comprehensive changes in molecular mediators associated with the disease. Amongst these technologies, genomics and epigenomics - including methylomics and miRNomics, have emerged as important tools to aid our biological understanding of disease. DESIGN: In this narrative review, we selected articles discussing advancements and applications of these technologies to OA biology and pathology. We discuss how genomics, deoxyribonucleic acid (DNA) methylomics, and miRNomics have uncovered disease-related molecular markers in the local and systemic tissues or fluids of OA patients. RESULTS: Genomics investigations into the genetic links of OA, including using genome-wide association studies, have evolved to identify 100+ genetic susceptibility markers of OA. Epigenomic investigations of gene methylation status have identified the importance of methylation to OA-related catabolic gene expression. Furthermore, miRNomic studies have identified key microRNA signatures in various tissues and fluids related to OA disease. CONCLUSIONS: Sharing of standardized, well-annotated omic datasets in curated repositories will be key to enhancing statistical power to detect smaller and targetable changes in the biological signatures underlying OA pathogenesis. Additionally, continued technological developments and analysis methods, including using computational molecular and regulatory networks, are likely to facilitate improved detection of disease-relevant targets, in-turn, supporting precision medicine approaches and new treatment strategies for OA.

Design, Synthesis, and Biological Evaluation of Novel Coumarin Analogs Targeted against SARS-CoV-2.

SARS-CoV, an RNA virus, is contagious and displays a remarkable degree of adaptability, resulting in intricate disease presentations marked by frequent genetic mutations that can ultimately give rise to drug resistance. Targeting its viral replication cycle could be a potential therapeutic option to counter its viral growth in the human body leading to the severe infectious stage. The Mpro of SARS-CoV-2 is a promising target for therapeutic development as it is crucial for viral transcription and replication. The derivatives of ß-diketone and coumarin have already been reported for their antiviral potential and, thus, are considered as a potential scaffold in the current study for the computational design of potential analogs for targeting the viral replication of SARS-CoV-2. In our study, we used novel diketone-hinged coumarin derivatives against the SARS-CoV-2 MPro to develop a broad-spectrum antiviral agent targeting SARS-CoV-2. Through an analysis of pharmacokinetics and docking studies, we identified a list of the top 10 compounds that demonstrated effectiveness in inhibiting the SARS-CoV-2 MPro virus. On the basis of the pharmacokinetics and docking analyses, the top 5 novel coumarin analogs were synthesized and characterized. The thermodynamic stability of compounds KS82 and KS94 was confirmed by their molecular dynamics, and the stability of the simulated system indicated their inhibitory nature. Molecules KS82 and KS94 were further evaluated for their anti-viral potential using Vero E6 cells followed by RT-PCR assay against SARS-CoV-2. The test compound KS82 was the most active with the potential to inhibit SARS-CoV-2 replication in Vero E6 cells. These data indicate that KS82 prevents the attack of the virus and emerges as the primary candidate with promising antiviral properties.

Proteomic and genomic profiling of plasma exosomes from patients with ankylosing spondylitis.

INTRODUCTION: Recent advances in understanding the biology of ankylosing spondylitis (AS) using innovative genomic and proteomic approaches offer the opportunity to address current challenges in AS diagnosis and management. Altered expression of genes, microRNAs (miRNAs) or proteins may contribute to immune dysregulation and may play a significant role in the onset and persistence of inflammation in AS. The ability of exosomes to transport miRNAs across cells and alter the phenotype of recipient cells has implicated exosomes in perpetuating inflammation in AS. This study reports the first proteomic and miRNA profiling of plasma-derived exosomes in AS using comprehensive computational biology analysis. METHODS: Plasma samples from patients with AS and healthy controls (HC) were isolated via ultracentrifugation and subjected to extracellular vesicle flow cytometry analysis to characterise exosome surface markers by a multiplex immunocapture assay. Cytokine profiling of plasma-derived exosomes and cell culture supernatants was performed. Next-generation sequencing was used to identify miRNA populations in exosomes enriched from plasma fractions. CD4+ T cells were sorted, and the frequency and proliferation of CD4+ T-cell subsets were analysed after treatment with AS-exosomes using flow cytometry. RESULTS: The expression of exosome marker proteins CD63 and CD81 was elevated in the patients with AS compared with HC (q<0.05). Cytokine profiling in plasma-derived AS-exosomes demonstrated downregulation of interleukin (IL)-8 and IL-10 (q<0.05). AS-exosomes cocultured with HC CD4+ T cells induced significant upregulation of IFNα2 and IL-33 (q<0.05). Exosomes from patients with AS inhibited the proliferation of regulatory T cells (Treg), suggesting a mechanism for chronically activated T cells in this disease. Culture of CD4+ T cells from healthy individuals in the presence of AS-exosomes reduced the proliferation of FOXP3+ Treg cells and decreased the frequency of FOXP3+IRF4+ Treg cells. miRNA sequencing identified 24 differentially expressed miRNAs found in circulating exosomes of patients with AS compared with HC; 22 of which were upregulated and 2 were downregulated. CONCLUSIONS: Individuals with AS have different immunological and genetic profiles, as determined by evaluating the exosomes of these patients. The inhibitory effect of exosomes on Treg in AS suggests a mechanism contributing to chronically activated T cells in this disease.

Individual participant data meta-analysis of metabolomics on sustained knee pain in primary osteoarthritis patients.

OBJECTIVES: Knee pain is the major driver for OA patients to seek healthcare, but after pursuing both conservative and surgical pain interventions, ∼20% of patients continue to report long-term pain following total knee arthroplasty (TKA). This study aimed to identify a metabolomic signature for sustained knee pain after TKA to elucidate possible underlying mechanisms. METHODS: Two independent cohorts from St John's, NL, Canada (n = 430), and Toronto, ON, Canada (n = 495) were included in the study. Sustained knee pain was assessed using the WOMAC pain subscale (five questions) at least 1 year after TKA for primary OA. Those reporting any pain on all five questions were considered to have sustained knee pain. Metabolomic profiling was performed on fasted pre-operative plasma samples using the Biocrates Absolute IDQ p180 kit. Associations between metabolites and pair-wise metabolite ratios with sustained knee pain in each individual cohort were assessed using logistic regression with adjustment for age, sex and BMI. Random-effects meta-analysis using inverse variance as weights was performed on summary statistics from both cohorts. RESULTS: One metabolite, phosphatidylcholine (PC) diacyl (aa) C28:1 (odds ratio = 0.66, P = 0.00026), and three metabolite ratios, PC aa C32:0 to PC aa C28:1, PC aa C28:1 to PC aa C32:0, and tetradecadienylcarnitine (C14:2) to sphingomyelin C20:2 (odds ratios = 1.59, 0.60 and 1.59, respectively; all P < 2 × 10-5), were significantly associated with sustained knee pain. CONCLUSIONS: Though further investigations are needed, our results provide potential predictive biomarkers and drug targets that could serve as a marker for poor response and be modified pre-operatively to improve knee pain and surgical response to TKA.

Fibroblast-like synoviocytes: Role in synovial fibrosis associated with osteoarthritis.

The synovial membrane undergoes a variety of structural changes throughout the pathogenesis of osteoarthritis (OA), including the development of fibrosis. Fibroblast-like synoviocytes (FLS) are a heterogenous cell population of the synovium that are suggested to drive the fibrotic response, but the exact mechanisms associated with their activation in OA remain unclear. Once activated, FLS are suggested to acquire a myofibroblast-like phenotype that drives fibrogenesis through excessive extracellular matrix (ECM) component deposition and an enhanced contractile function. In this review, we define FLS in the synovium, discuss how select extracellular or endogenous factors potentially induce their activation in OA, and describe how the activity of myofibroblast-like cells affects the structure of the synovial membrane.

Understanding osteoarthritis pathogenesis: a multiomics system-based approach.

PURPOSE OF REVIEW: Osteoarthritis is a heterogeneous, multifactorial condition regulated by complex biological interactions at multiple levels. Comprehensive understanding of these regulatory interactions is required to develop feasible advances to improve patient outcomes. Improvements in technology have made extensive genomic, transcriptomic, epigenomic, proteomic, and metabolomic profiling possible. This review summarizes findings over the past 20 months related to omics technologies in osteoarthritis and examines how using a multiomics approach is necessary for advancing our understanding of osteoarthritis as a disease to improve precision osteoarthritis treatments. RECENT FINDINGS: Using the search terms 'genomics' or 'transcriptomics' or 'epigenomics' or 'proteomics' or 'metabolomics' and 'osteoarthritis' from January 1, 2018 to August 31, 2019, we identified advances in omics approaches applied to osteoarthritis. Trends include untargeted whole genome, transcriptome, proteome, and metabolome analyses leading to identification of novel molecular signatures, cell subpopulations and multiomics validation approaches. SUMMARY: To address the complexity of osteoarthritis, integration of multitissue analyses by multiomics approaches with the inclusion of longitudinal clinical data is necessary for a comprehensive understanding of the disease process, and for appropriate development of efficacious diagnostics, prognostics, and biotherapeutics.

One-Pot C-H Arylation/Lactamization Cascade Reaction of Free Benzylamines.

An efficient method has been developed for the synthesis of seven-membered biaryl lactams involving Pd-catalyzed, native amine-directed, ortho-arylation of benzylamines followed by in situ lactamization. This cascade sequence is enabled by the use of 2-iodobenzoates, which facilitates C-H arylation from the free amine under conditions that typically require an improved directing group approach. This reaction is characterized by a broad substrate scope with good functional group tolerance. The need for an ester versus carboxylic acid-functionalized coupling partner is also explored, as is the potential for synthesizing eight-membered biaryl lactams. Various applications are also investigated, including access to the aza-brassinolide core.

Leucettamine B analogs and their carborane derivative as potential anti-cancer agents: Design, synthesis, and biological evaluation.

Leucettamine B is a natural product found in marine sponge Leucetta microraphis. Several of analogs of its family, such as aplysinopsine and clathridine, are medicinally active molecules which have applications in many pharmaceuticals and healthcare products; however, thus far, leucettamine B has not been studied. In this report, we describe the synthesis of a new class of analogs of leucettamine B obtained by Knoevenagel condensation using a microwave reactor. The 25 newly synthesized compounds were tested against MDA-MB-468, SW480, and Mahlavu cell lines for anticancer activity. Among them, the carborane-based compound (Z)-5-(benzo[d][1,3]dioxol-5-ylmethylene)-3-(1-closo-carboranyl)-2-thioxo -thiazolidin-4-one (49) and (Z)-5-(benzo[d][1,3]dioxol-5-ylmethylene)-3-(2-(pyrrolidin-1-yl)ethyl)-2-thioxothiazolidin-4-one (31) derivatives were found to have the most potential for use against tumor cells. The carborane derivative 49 had the lowest IC50 value against the SW480 cell line (4.7 µM) and the Mahlavu (6.6 µM) cell line. Furthermore, compound 31 also had a low IC50 value against SW480 (7.5 µM). Our research shows that leucettamine B analogs might have potential for use in cancer chemotherapy.

Carbon Dioxide-Mediated C( sp2)-H Arylation of Primary and Secondary Benzylamines.

C-C bond formation by transition metal-catalyzed C-H activation has become an important strategy to fabricate new bonds in a rapid fashion. Despite the pharmacological importance of ortho-arylbenzylamines, however, effective ortho-C-C bond formation of free primary and secondary benzylamines using PdII remains an outstanding challenge. Presented herein is a new strategy for constructing ortho-arylated primary and secondary benzylamines mediated by carbon dioxide (CO2). The use of CO2 with Pd is critical to allowing this transformation to proceed under relatively mild conditions, and mechanistic studies indicate that it (CO2) is directly involved in the rate-determining step. Furthermore, the milder temperatures furnish free amine products that can be directly used or elaborated without the need for deprotection. In cases where diarylation is possible, an interesting chelate effect is shown to facilitate selective monoarylation.

microRNA-181a-5p antisense oligonucleotides attenuate osteoarthritis in facet and knee joints.

OBJECTIVES: We recently identified microRNA-181a-5p (miR-181a-5p) as a critical mediator involved in the destruction of lumbar facet joint (FJ) cartilage. In this study, we tested if locked nucleic acid (LNA) miR-181a-5p antisense oligonucleotides (ASO) could be used as a therapeutic to limit articular cartilage degeneration. METHODS: We used a variety of experimental models consisting of both human samples and animal models of FJ and knee osteoarthritis (OA) to test the effects of LNA-miR-181a-5p ASO on articular cartilage degeneration. Histopathological analysis including immunohistochemistry and in situ hybridisation were used to detect key OA catabolic markers and microRNA, respectively. Apoptotic/cell death markers were evaluated by flow cytometry. qPCR and immunoblotting were applied to quantify gene and protein expression. RESULTS: miR-181a-5p expression was increased in human FJ OA and knee OA cartilage as well as injury-induced FJ OA (rat) and trauma-induced knee OA (mouse) cartilage compared with control cartilage, correlating with classical OA catabolic markers in human, rat and mouse cartilage. We demonstrated that LNA-miR-181a-5p ASO in rat and mouse chondrocytes reduced the expression of cartilage catabolic and chondrocyte apoptotic/cell death markers in vitro. Treatment of OA-induced rat FJ or mouse knee joints with intra-articular injections of in vivo grade LNA-miR-181a-5p ASO attenuated cartilage destruction, and the expression of catabolic, hypertrophic, apoptotic/cell death and type II collagen breakdown markers. Finally, treatment of LNA-miR-181a-5p ASO in cultures of human knee OA chondrocytes (in vitro) and cartilage explants (ex vivo) further demonstrated its cartilage protective effects. CONCLUSIONS: Our data demonstrate, for the first time, that LNA-miR-181a-5p ASO exhibit cartilage-protective effects in FJ and knee OA.

Ephrins and Eph Receptor Signaling in Tissue Repair and Fibrosis.

PURPOSE OF REVIEW: Fibrosis is a pathological feature of many human diseases that affect multiple organs. The development of anti-fibrotic therapies has been a difficult endeavor due to the complexity of signaling pathways associated with fibrogenic processes, complicating the identification and modulation of specific targets. Evidence suggests that ephrin ligands and Eph receptors are crucial signaling molecules that contribute to physiological wound repair and the development of tissue fibrosis. Here, we discuss recent advances in the understanding of ephrin and Eph signaling in tissue repair and fibrosis. RECENT FINDINGS: Ephrin-B2 is implicated in fibrosis of multiple organs. Intercepting its signaling may help counteract fibrosis. Ephrins and Eph receptors are candidate mediators of fibrosis. Ephrin-B2, in particular, promotes fibrogenic processes in multiple organs. Thus, therapeutic strategies targeting Ephrin-B2 signaling could yield new ways to treat organ fibrosis.

Design and Synthesis of Benzimidazole-Chalcone Derivatives as Potential Anticancer Agents.

Numerous reports have shown that conjugated benzimidazole derivatives possess various kinds of biological activities, including anticancer properties. In this report, we designed and synthesized 24 new molecules comprising a benzimidazole ring, arene, and alkyl chain-bearing cyclic moieties. The results showed that the N-substituted benzimidazole derivatives bearing an alkyl chain and a nitrogen-containing 5- or 6-membered ring enhanced the cytotoxic effects on human breast adenocarcinoma (MCF-7) and human ovarian carcinoma (OVCAR-3) cell lines. Among the 24 synthesized compounds, (2E)-1-(1-(3-morpholinopropyl)-1H-benzimidazol-2 -yl)-3-phenyl-2-propen-1-one) (23a) reduced the proliferation of MCF-7 and OVCAR-3 cell lines demonstrating superior outcomes to those of cisplatin.

Carbon Dioxide-Mediated C(sp3)-H Arylation of Amine Substrates.

Elaborating amines via C-H functionalization has been an important area of research over the past decade but has generally relied on an added directing group or sterically hindered amine approach. Since free-amine-directed C(sp3)-H activation is still primarily limited to cyclization reactions and to improve the sustainability and reaction scope of amine-based C-H activation, we present a strategy using CO2 in the form of dry ice that facilitates intermolecular C-H arylation. This methodology has been used to enable an operationally simple procedure whereby 1° and 2° aliphatic amines can be arylated selectively at their γ-C-H positions. In addition to potentially serving as a directing group, CO2 has also been demonstrated to curtail the oxidation of sensitive amine substrates.

The in vivo effect of prophylactic subchondral bone protection of osteoarthritic synovial membrane in bone-specific Ephb4-overexpressing mice.

Osteoarthritis (OA) is characterized by progressive joint destruction, including synovial membrane alteration. EphB4 and its ligand ephrin-B2 were found in vitro to positively affect OA subchondral bone and cartilage. In vivo in an experimental mouse model overexpressing bone-specific Ephb4 (TgEphB4), a protective effect was found on both the subchondral bone and cartilage during OA. We investigated in the TgEphB4 mouse model the in vivo effect on synovial membrane during OA. Knee OA was surgically induced by destabilization of the medial meniscus (DMM). Synovial membrane was evaluated using histology, histomorphometry, IHC, and real-time PCR. Compared to DMM-wild-type (WT) mice, DMM-TgEphB4 mice had a significant decrease in synovial membrane thickness, vascular endothelial growth factor, and the profibrotic markers fibrin, type 1 procollagen, type 3 collagen, connective tissue growth factor, smooth muscle actin-α, cartilage oligomeric matrix protein, and procollagen-lysine, and 2-oxoglutarate 5-dioxygenase 2. Moreover, factors known to modulate transforming growth factor-ß signaling, transforming growth factor receptor 1/ALK1, phosphorylated Smad-1, and heat shock protein 90ß were significantly decreased in DMM-TgEphB4 compared with DMM-WT mice. Ephb4 overexpression also exhibited a protective effect on synovial membrane thickness of aged (24-month-old) mice. Overexpression of bone-specific Ephb4 clearly demonstrated prevention of the development and/or progression of fibrosis in OA synovial membrane, reinforcing the hypothesis that protecting the subchondral bone prophylactically and during OA reduces the pathologic changes in other articular tissues.