Brief Report: Distinct Dysregulation of the Small Leucine‐Rich Repeat Protein Family in Osteoarthritic Acetabular Labrum Compared to Articular Cartilage

Elevated secretion of pro-collagen I-alpha and vascular endothelial growth factor as biomarkers of acetabular labrum degeneration and calcification in hip osteoarthritis: An explant study

Background

Hip osteoarthritis (OA) involves structural degeneration of different joint compartments, including femoral head cartilage, periarticular ligaments and the acetabular labrum. However, the molecular mechanisms underlying labrum degeneration in hip OA remain poorly understood.

Aim

To assess secretion of putative biomarkers for OA from explanted human labrum tissues under basal and inflammatory conditions and to determine whether these could differentiate between OA and calcification status compared to fracture controls.

Methods

Intact labrum specimens were collected from patients undergoing joint arthroplasty for primary hip OA (n ​= ​15, mean age 70) or non-OA femoral neck fracture (n ​= ​5, mean age 64). Tissues were dissected in equal-sized samples and explanted for one week. To mimic activation of inflammatory signaling by endogenous damage-associated molecular patterns (DAMP) tissue were stimulated with a toll-like receptor 4 (TLR4) agonist (1 ​μg/mL LPS). The involvement of transforming growth factor-beta (TGF-beta) signaling was evaluated by treatment with a TGF-beta type 1 receptor inhibitor (10 ​μM SB-505124). Secretion of aggrecan (ACAN), pro-collagen-I alpha (Pro-Col-Iα), cartilage oligomeric matrix protein (COMP), interleukin-6 (IL-6) and vascular endothelial growth factor (VEGF) was assessed by enzyme-linked immunosorbent assay (ELISA). Labrum calcification was evaluated by 3D whole mount fluorescent microscopy of ethyl cinnamate-based optically cleared tissues stained with Alcian blue/Alizarin red.

Results

Whole mount microscopy revealed non-OA fracture controls were non-calcified, whereas six OA labra (40%) were partially calcified or ossified. Basal secretion of Pro-Col-Iα and VEGF was increased four-fold in OA versus non-OA labra. Pro-Col-Iα levels were correlated with those of VEGF (r ​= ​0.65) and COMP (r ​= ​0.54). Stimulation of DAMP signaling through TLR4 affected secretion of IL-6, VEGF, COMP and Pro-Col-Iα, with distinct responses between non-OA and OA tissues. Inhibition of TGF-beta signaling specifically reduced elevated secretion of Pro-Col- Iα and VEGF in calcified OA labrum.

Conclusions

Secretion of the putative OA biomarkers Pro-Col-Iα and VEGF is elevated in degenerated human acetabular labrum and may serve as indicators of OA and calcification status. Secretion of both factors was partially regulated by TGF-beta signaling in calcified OA labrum tissues.The Translational potential of this article:Our findings suggest that a biomarker panel consisting of Pro-Col-Iα/VEGF/COMP may be valuable for assessing subradiographic labrum degeneration and calcification in hip OA. Targeting TGF-beta signaling may offer a means to reduce vascular invasion and fibrosis in acetabular labrum tissue.

Identifying Muscle Function-based Phenotypes Associated With Radiographic Progression of Secondary Hip Osteoarthritis

OBJECTIVE

The purposes of our study were to (1) identify muscle function-based clinical phenotypes in patients with hip osteoarthritis (OA) and (2) determine the association between those phenotypes and radiographic progression of hip OA.

DESIGN

Prospective cohort study.

SETTING

Clinical biomechanics laboratory of a university.

PARTICIPANTS

Fifty women patients with mild-to-moderate secondary hip OA (N=50) were recruited from the orthopedic department of a single institution.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Two-step cluster analyses were performed to classify the patients, using hip flexion, extension, abduction, and external/internal rotation muscle strength (cluster analysis 1); relative hip muscle strength to total hip strength (ie, hip muscle strength balance; cluster analysis 2); and both hip muscle strength and muscle strength balance (cluster analysis 3) as variables. The association between the phenotype and hip OA progression over 12 months (indicated by joint space width [JSW] >0.5 mm) was investigated by logistic regression analyses. Hip joint morphology, hip pain, gait speed, physical activity, Harris hip score, and SF-36 scores were compared between the phenotypes.

RESULTS

Radiographic progression of hip OA was observed in 42% of the patients. The patients were classified into 2 phenotypes in each of the 3 cluster analyses. The solution in cluster analyses 1 and 3 was similar, and high-function and low-function phenotypes were identified; however, no association was found between the phenotypes and hip OA progression. The phenotype 2-1 (high-risk phenotype) extracted in cluster analysis 2, which had relative muscle weakness in hip flexion and internal rotation, was associated with subsequent hip OA progression, even after adjusting for age and minimum JSW at baseline (adjusted odds ratio [95% confidence interval], 3.60 [1.07-12.05]; P=.039).

CONCLUSION

As preliminary findings, the phenotype based on hip muscle strength balance, rather than hip muscle strength, may be associated with hip OA progression.

Osteomodulin downregulation is associated with osteoarthritis development

Abnormal subchondral bone remodeling leading to sclerosis is a main feature of osteoarthritis (OA), and osteomodulin (OMD), a proteoglycan involved in extracellular matrix mineralization, is associated with the sclerotic phenotype. However, the functions of OMD remain poorly understood, specifically in vivo. We used Omd knockout and overexpressing male mice and mutant zebrafish to study its roles in bone and cartilage metabolism and in the development of OA. The expression of Omd is deeply correlated with bone and cartilage microarchitectures affecting the bone volume and the onset of subchondral bone sclerosis and spontaneous cartilage lesions. Mechanistically, OMD binds to RANKL and inhibits osteoclastogenesis, thus controlling the balance of bone remodeling. In conclusion, OMD is a key factor in subchondral bone sclerosis associated with OA. It participates in bone and cartilage homeostasis by acting on the regulation of osteoclastogenesis. Targeting OMD may be a promising new and personalized approach for OA.

The acetabular labrum tissue shows unique transcriptome signatures compared to cartilage and responds to combined cyclic compression and surface shearing

The labrum is a fibrocartilaginous ring surrounding the acetabulum. Loss of labrum function contributes to the degeneration of the hip joint, leading to osteoarthritis. Successful labrum restoration requires profound knowledge about the tissue being replaced. The aim of this study was to characterize the transcriptome and the mechanobiological function of the labrum. RNA-seq was performed to compare the transcriptome of bovine labrum against articular cartilage tissue. Differential expression and gene ontology (GO) term pathway analysis were applied using the SUSHI framework. Bovine labrum explants were cultured for 5 days with / without mechanical loading and targeted gene expression was analyzed by real time quantitative polymerase chain reaction. More than 6'000 genes were significantly differentially expressed in the labrum compared to cartilage. Up- and downregulated genes were associated with the GO term extracellular matrix organization. The study established an extracellular matrix gene expression profile of healthy labrum tissue and identified significantly upregulated extracellular matrix related genes compared to cartilage tissue. Mechanical loading significantly upregulated aggrecan (ACAN), cartilage oligomeric matrix protein (COMP), fibronectin (FN1) and proteoglycan 4 (PRG4). MMP1/3/9 and IL6, which were upregulated by an inflammatory stimulus (IL-1b), were statistically unaffected by the loading, although IL6 was upregulated in each donor immediately after the loading. Unique ECM related features may guide the development of labrum tissue-engineering solutions. Despite the transcriptome differences between labrum and cartilage tissue, gene expression response to mechanical loading showed similarities with previously reported responses in cartilage, indicating a preserved tissue adaptation mechanism to mechanical loading. Running title: Acetabular Labrum Mechanobiology.

Osteoglycin: An ECM Factor Regulating Fibrosis and Tumorigenesis

The extracellular matrix (ECM) is made up of noncellular components that have special properties for influencing cell behavior and tissue structure. Small leucine-rich proteoglycans (SLRPs) are nonfibrillar ECM components that serve as structural scaffolds and signaling molecules. osteoglycin (OGN), a class III SLRP, is a ubiquitous ECM component that not only helps to organize the extracellular matrix but also regulates a number of important biological processes. As a glycosylated protein in the ECM, OGN was originally considered to be involved in fiber assembly and was reported to have a connection with fibrosis. In addition to these functions, OGN is found in a variety of cancer tissues and is implicated in cellular processes linked to tumorigenesis, including cell proliferation, invasion, metastasis, and epithelial-mesenchymal transition (EMT). In this review, we summarize the structure and functions of OGN as well as its biological and clinical importance in the context of fibrotic illness and tumorigenesis. This review aims to improve our understanding of OGN and provide some new strategies for the treatment of fibrosis and cancer.

Single-cell RNA sequencing deconvolutes the in vivo heterogeneity of human bone marrow-derived mesenchymal stem cells

Bone marrow-derived mesenchymal stem cells (BM-MSCs) are multipotent stromal cells that have a critical role in the maintenance of skeletal tissues such as bone, cartilage, and the fat in bone marrow. In addition to providing microenvironmental support for hematopoietic processes, BM-MSCs can differentiate into various mesodermal lineages including osteoblast/osteocyte, chondrocyte, and adipocyte that are crucial for bone metabolism. While BM-MSCs have high cell-to-cell heterogeneity in gene expression, the cell subtypes that contribute to this heterogeneity in vivo in humans have not been characterized. To investigate the transcriptional diversity of BM-MSCs, we applied single-cell RNA sequencing (scRNA-seq) on freshly isolated CD271+ BM-derived mononuclear cells (BM-MNCs) from two human subjects. We successfully identified LEPRhiCD45low BM-MSCs within the CD271+ BM-MNC population, and further codified the BM-MSCs into distinct subpopulations corresponding to the osteogenic, chondrogenic, and adipogenic differentiation trajectories, as well as terminal-stage quiescent cells. Biological functional annotations of the transcriptomes suggest that osteoblast precursors induce angiogenesis coupled with osteogenesis, and chondrocyte precursors have the potential to differentiate into myocytes. We also discovered transcripts for several clusters of differentiation (CD) markers that were either highly expressed (e.g., CD167b, CD91, CD130 and CD118) or absent (e.g., CD74, CD217, CD148 and CD68) in BM-MSCs, representing potential novel markers for human BM-MSC purification. This study is the first systematic in vivo dissection of human BM-MSCs cell subtypes at the single-cell resolution, revealing an insight into the extent of their cellular heterogeneity and roles in maintaining bone homeostasis.

Osteomodulin is a Potential Genetic Target for Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is one of the most common genetic heart diseases. Its features include abnormal cardiomyocyte hypertrophy, microvascular dysfunction, and increased accumulation of intercellular matrix. We aim to unravel genes associated with the pathogenesis of HCM and provide a potential target for diagnosis and treatment. Key modules were identified by weighted gene co-expression network analysis (WGCNA). A miRNA-mRNA network was constructed with the predicted miRNA and the most likely hub gene was screened out for gene set enrichment analysis (GSEA). The diagnostic capacity of hub gene was verified by receiver operating characteristic (ROC) curves. Single-cell sequencing (sc-RNA seq) data of normal adult hearts were used to further predict the specific cell types expressing the hub gene. WGCNA assigned genes into different modules and found that the genes contained in the red module had the strongest positive correlation with HCM disease. 2.5% of the genes were common between DEG and hub genes. With the miRNA-mRNA network, osteomodulin (OMD) was identified as the most potential hub gene. GSEA showed that OMD was mainly involved in the synthesis of extracellular matrix and had a certain inhibitory effect on the immune system. The expression of OMD in HCM was validated and ROC curve analysis showed that OMD could distinguish HCM from controls with the area under the curve (AUC) > 0.7. The sc-RNA seq revealed that OMD was mainly expressed in the later stages of cardiac fibroblasts, suggesting that OMD may have an effect on fibroblasts, participating in the pathogenesis of HCM. OMD may serve as a biomarker and therapeutic target for HCM in the future.

Osteomodulin positively regulates osteogenesis through interaction with BMP2

Osteomodulin (OMD), a member of the small leucine-rich proteoglycan family, distributes in mineralized tissues and is positively regulated by bone morphogenetic protein 2 (BMP2). However, the exact function of OMD during mineralization and its association with BMP2 remain poorly understood. Herein, the expression pattern of OMD during osteogenesis was investigated in human dental pulp stem cells. Silencing OMD gene significantly suppressed the alkaline phosphatase activity, mineralized nodule formation and osteogenesis-associated gene transcription. Besides, OMD could enhance BMP2-induced expression of SP7 and RUNX2 with concentration dependence in vitro. Rat mandibular bone defect model revealed that scaffolds injected with the combination of OMD and suboptimal BMP2 exhibited more mature and abundant mineralized bone than that treated with OMD or suboptimal BMP2 alone. Mechanistically, OMD could bind to BMP2 via its terminal leucine-rich repeats and formed complexes with BMP2 and its membrane receptors, thus promoting BMP/SMAD signal transduction. In addition, OMD was a putative target gene of SMAD4, which plays a pivotal role in this pathway. Collectively, these data elucidate that OMD may act as a positive coordinator in osteogenesis through BMP2/SMADs signaling.

Identifying the role of ASPN and COMP genes in knee osteoarthritis development

Background

Osteoarthritis (OA) is a common cause of musculoskeletal disability among elders and is characterized by late-onset degeneration of articular cartilage. OA affects various joints, commonly hand, knee, and hip, with clinical features that are unique to each joint. This study was initiated to identify and evaluate the role of the ASPN and COMP genes in the development of knee OA.

Methods

A case–control study was carried out involving 500 cases with knee OA (diagnosed by the American College of Rheumatology) and an equal number of healthy controls. Blood was drawn for genomic DNA isolation. PCR-RFLP and TaqMan assay methods were used to identify the SNPs. mRNA and protein expression of genes were carried out in peripheral blood lymphocytes (PBLs) by RT-PCR and Western immunoblotting. The data obtained were analyzed for the statistical significance between control and case groups.

Results

The variant genotype of ASPN and COMP genes was found to be present at a relatively higher frequency in cases than controls. RT-PCR and immunochemical studies revealed increased mRNA and protein expression of such gene in PBLs isolated from cases of knee OA as compared to healthy control.

Conclusion

The allelic alteration in ASPN and COMP genes in knee OA cases points to the role of these genes in the development of knee OA. Further, increased mRNA and protein expression of ASPN and COMP in peripheral blood samples of patients with the disease suggest that expression profile of candidate gene could be used as a biomarker for predicting the development and progression of knee OA.

Mechanical strain promotes skin fibrosis through LRG-1 induction mediated by ELK1 and ERK signalling

Biomechanical force and pathological angiogenesis are dominant features in fibro-proliferative disorders. Understanding the role and regulation of the mechanical microenvironment in which pathological angiogenesis occurs is an important challenge when investigating numerous angiogenesis-related diseases. In skin fibrosis, dermal fibroblasts and vascular endothelial cells are integral to hypertrophic scar formation. However, few studies have been conducted to closely investigate their relationship. Here we show, that leucine-rich-alpha-2-glycoprotein 1 (LRG-1) a regulator of pathological angiogenesis, links biomechanical force to angiogenesis in skin fibrosis. We discover that LRG-1 is overexpressed in hypertrophic scar tissues, and that depletion of Lrg-1 in mouse skin causes mild neovascularization and skin fibrosis formation in a hypertrophic scarring model. Inhibition of FAK or ERK attenuates LRG-1 expression through the ELK1 transcription factor, which binds to the LRG-1 promoter region after transcription initiation by mechanical force. Using LRG-1 to uncouple mechanical force from angiogenesis may prove clinically successful in treating fibro-proliferative disorders.

Significantly dysregulated genes in osteoarthritic labrum cells identified through gene expression profiling

The aim of the present study was to explore the molecular basis and identify significant genetic alterations in acetabular labrum cells associated with osteoarthritis (OA). Gene expression data of osteoarthritic and normal human labrum cells were downloaded from a public database and reanalyzed. Significant differentially expressed genes (DEGs) were acquired by performing a thorough analysis of microarray data between the OA acetabular labrum cells and control cells. Key genes in OA labrum cells were revealed by a combination of weighted gene co-expression network analysis (WGCNA) and protein-protein interaction (PPI) analysis. Literature mining and drug screening were further performed for these key genes. In total, 141 DEGs between OA and normal labrum cells were identified. In addition, WGCNA and PPI analysis identified 23 DEGs as key genes in the OA labrum. All the key genes were significantly downregulated in OA labrum cells and were grouped into two different WGCNA-PPI common subnetworks. Kinase insert domain receptor (KDR), CD34, cadherin 5 (CDH5), Fms related tyrosine kinase 1 (FLT1) and asporin were hub nodes in the PPI network of DEGs. These key genes were significantly enriched in functional clusters of transforming growth factor, alkaline phosphatase, bone morphogenic protein and extracellular matrix. Drug screening analysis identified several drugs targeting the key genes, including arachidonic acid, yohimbic acid and mimosine. The results of the present study indicate that the changes of FLT1, KDR, CD34 and CDH5 in acetabular labrum cells may be involved in the pathogenesis of OA and could serve as biomarkers and therapeutic targets of OA. Additionally, arachidonic acid, yohimbic acid and mimosine may act as potential drugs for OA.

Labral calcification in end-stage osteoarthritis of the hip correlates with pain and clinical function

The acetabular labrum of the hip (ALH) is recognized as a clinically important structure, but knowledge about the pathophysiology of this fibrocartilage is scarce. In this prospective study we determined the prevalence of ALH calcification in patients with end-stage osteoarthritis (OA) and analyzed the relationship of cartilage calcification (CC) with hip pain and clinical function. Cohort of 80 patients (70.2 ± 7.6years) with primary OA scheduled for total hip replacement. Harris Hip Score (HHS) was recorded preoperatively. Total ALH and femoral head (FH) were sampled intraoperatively. CC of the ALH and FH was analyzed by high-resolution digital contact radiography. Histological degeneration of the ALH (Krenn-Score) and FH (OARSI-Score) was determined. Multivariate linear regression model and partial correlation analyses were performed. The prevalence of cartilage calcification both in the ALH and FH was 100%, while the amount of CC in the ALH was 1.55 times higher than in the FH (p < 0.001). There was a significant inverse regression between the amount of calcification of both the ALH and the FH and preoperative HHS (β_ALH  = -2.1, p = 0.04), (β_FH  = -2.9, p = 0.005), but pain was influenced only by ALH calcification (β_ALH  = -2.7, p = 0.008). Age-adjusted, there was a significant correlation between cartilage calcification and histological degeneration (ALH:r_s  = 0.53, p < 0.001/FH: r_s  = 0.30, p = 0.007). Fibrocartilage and articular cartilage calcification are inseparable pathological findings in end-stage osteoarthritis of the hip. Fibrocartilage calcification is associated with poor and painful hip function.

CLINICAL SIGNIFICANCE

ALH fibrocartilage appears to be particularly prone to calcification, which may explain higher pain levels in individuals with a high degree of ALH calcification independent of age and histological degeneration. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1248-1255, 2018.

Genetic polymorphism in the asporin gene is not a key risk factor for osteoarthritis: Evidence based on an updated cumulative meta-analysis

To provide an evidence-based medical basis for the treatment of osteoarthritis, a meta-analysis was performed to assess the association between asporin (ASPN) gene polymorphism and susceptibility to osteoarthritis (OA). The current study searched the literature from January 1st, 1915 through February 1st, 2017 using the Cochrane Library, PubMed, the Excerpta Medica database (EMBASE) and three main Chinese databases (VIP, CNKI and Wan Fang). Cohort and case-control studies that explored the association between different types of ASPN alleles and OA susceptibility were evaluated. The K/L grading system, clinical and radiological diagnoses were used for OA diagnosis. A random-effects model was used in a pooled analysis to adjust for heterogeneity of the included studies, and the differences between treatment groups were reported as odds ratio (OR), 95% confidence intervals (CIs) and P-values. Begg's funnel plots and Egger's tests were used to assess publication bias in the present meta-analysis. Following document retrieval and screening, a total of 10 studies were deemed eligible, including 4,842 patients and 3,661 healthy subjects. Results of the multivariate meta-regression analysis revealed that the study sample size was a source of heterogeneity between studies. The D17 allele was a risk factor for the development of OA (OR=1.33, 95% CI: 1.02–1.73, P<0.05). The other alleles were not considered as risk factors for development of OA (P>0.05). The results of the meta-analysis verified that ASPN polymorphisms were not significantly relevant to an increased OA risk. However, the mechanisms contributing to the association between ASPN polymorphisms and OA risk still require further study.

Comparison of secretome from osteoblasts derived from sclerotic versus non-sclerotic subchondral bone in OA: A pilot study

Objective

Osteoarthritis (OA) is characterized by cartilage degradation but also by other joint tissues modifications like subchondral bone sclerosis. In this study, we used a proteomic approach to compare secretome of osteoblast isolated from sclerotic (SC) or non sclerotic (NSC) area of OA subchondral bone.

Design

Secretome was analyzed using differential quantitative and relative label free analysis on nanoUPLC G2 HDMS system. mRNA of the more differentially secreted proteins were quantified by RT-PCR in cell culture from 5 other patients. Finally, osteomodulin and fibulin-3 sequences were quantified by western blot and immunoassays in serum and culture supernatants.

Results

175 proteins were identified in NSC osteoblast secretome. Data are available via ProteomeXchange with identifier PXD008494. Compared to NSC osteoblast secretome, 12 proteins were significantly less secreted (Osteomodulin, IGFBP5, VCAM-1, IGF2, 78 kDa glucose-regulated protein, versican, calumenin, IGFBP2, thrombospondin-4, periostin, reticulocalbin 1 and osteonectin), and 13 proteins were significantly more secreted by SC osteoblasts (CHI3L1, fibulin-3, SERPINE2, IGFBP6, SH3BGRL3, SERPINE1, reticulocalbin3, alpha-2-HS-glycoprotein, TIMP-2, IGFBP3, TIMP-1, SERPINF1, CSF-1). Similar changes in osteomodulin, IGF2, SERPINE1, fibulin-3 and CHI3L1 mRNA levels were observed. ELISAs assays confirm the decrease by half of osteomodulin protein in SC osteoblasts supernatant compared to NSC and in OA patients serum compared to healthy subjects. Fibulin-3 epitopes Fib3-1, Fib3-2 and Fib3-3 were also increased in SC osteoblasts supernatant compared to NSC.

Conclusions

We highlighted some proteins differentially secreted by the osteoblasts coming from OA subchondral bone sclerosis. These changes contribute to explain some features observed in OA subchondral bone, like the increase of bone remodeling or abnormalities in bone matrix mineralization. Among identified proteins, osteomodulin was found decreased and fibulin-3 increased in serum of OA patients. These findings suggest that osteomodulin and fibulin-3 fragments could be biomarkers to monitor early changes in subchondral bone metabolism in OA.

The diverse functions of osteoglycin: a deceitful dwarf, or a master regulator of disease?

Small leucine-rich proteoglycans are emerging as important regulatory proteins within the extracellular matrix, where they exert both structural and nonstructural functions and hence are modulators of numerous biological processes, such as inflammation, fibrosis, and cell proliferation. One proteoglycan in particular, osteoglycin (OGN), also known as mimecan, shows great structural and functional diversity in normal physiology and in disease states, therefore making it a very interesting candidate for the development of novel therapeutic strategies. Unfortunately, the literature on OGN is confusing, as it has different names, and different transcript and protein variants have been identified. This review will give a clear overview of the different structures and functions of OGN that have been identified to date, portray its central role in pathophysiology, and highlight the importance of posttranslational processing, such as glycosylation, for the diversity of its functions.-Deckx, S., Heymans, S., Papageorgiou, A.-P. The diverse functions of osteoglycin: a deceitful dwarf, or a master regulator of disease?

Gene signatures in osteoarthritic acetabular labrum using microarray analysis

BACKGROUND

Osteoarthritis (OA) is the most common chronic joint disease. This study aimed to uncover underlying mechanisms of OA pathogenesis and explore the potential biomarkers of osteoarthritic acetabular labrum.

METHODS

The microarray data GSE60762 was utilized, containing five OA acetabular labrum samples and three healthy control samples. Data were preprocessed by oligo package and the differentially expressed genes (DEGs) were identified using limma package with predefined criteria, followed by functional enrichment analysis by the GoFunction in R Bioconductor, and protein-protein interaction (PPI) network analysis.

RESULTS

As a result, 141 DEGs (44 were up-regulated and 97 were down-regulated) were identified between OA and healthy acetabular labrum cells. Up-regulated genes including CDH2 and WNT5A were significantly enriched in intracellular signal transduction function, while down-regulated genes such as KDR, FLT1 and CDH5 were remarkably correlated with cardiovascular system development. FLT1, KDR, CDH2 and CDH5 were the striking nodes in the PPI network.

CONCLUSION

CDH2, WNT5A, KDR, FLT1 and CDH5 might serve as the biomarkers of OA prognosis. Intracellular signal transduction and cardiovascular system development might play significant roles in the destruction of labrum during OA progression. However, more experimental validations are warranted to confirm our findings.