Relationship between cartilage oligomeric matrix protein (COMP) and rheumatoid arthritis severity

Effects of Etanercept and Adalimumab on Serum Levels of Cartilage Remodeling Markers in Women with Rheumatoid Arthritis

Tumor necrosis factor α inhibitor (TNFαI) therapy is associated with a significant inhibition of radiographic progression, resulting in improved physical function and quality of life among patients with rheumatoid arthritis (RA). The mechanism by which TNFαI prevent joint destruction is still unknown. In this study, the effect of 15-month anti-TNF-α therapy in combination with methotrexate on circulating levels of biochemical markers of cartilage turnover in female RA patients was assessed. Serum levels of collagen type II C-terminal cleavage neoepitope (C2C), C-terminal propeptide of type II collagen (PIICP), cartilage oligomeric matrix protein (COMP), and matrix metalloproteinase-3 (MMP-3) were evaluated using immunoassays at baseline and 15 months after the start of TNFαI treatment. Baseline COMP, C2C, and MMP-3 levels and C2C/PIICP ratios were significantly higher in women with RA compared with those observed in the healthy subjects. No differences in PIICP levels between the controls and the women with RA were observed. After 15 months of TNFαI treatment, serum levels of C2C, COMP, and MMP-3 decreased, whereas the levels of PIICP increased but were still not different from those of the controls. These changes were accompanied by significantly reduced C2C/PIICP ratios. Before the start of TNFαI therapy, serum levels of COMP significantly correlated with the patients' ages (p < 0.05) and their 28-joint disease activity score values based on their erythrocyte sedimentation rates (DAS28-ESR; p < 0.05). Moreover, multiple linear regression analysis showed that baseline COMP levels retained a significant association with DAS28-ESR value (β = 287.74, p = 0.022, R2 model = 0.25) after model adjustments. The largest area under the ROC curve was obtained for C2C/PIICP ratios (AUC: 0.830, 95% CI: 0.727-0.932, p < 0.001). Our results suggest that long-term anti-TNF-α therapy combined with MTX has a beneficial effect on cartilage remodeling that is associated with clinical improvement among RA patients. Serum C2C/PIICP ratios may help to monitor the effectiveness of anti-TNF-α treatment among RA patients.

Cartilage Oligomeric Matrix Protein, Diseases, and Therapeutic Opportunities

Cartilage oligomeric matrix protein (COMP) is an extracellular matrix (ECM) glycoprotein that is critical for collagen assembly and ECM stability. Mutations of COMP cause endoplasmic reticulum stress and chondrocyte apoptosis, resulting in rare skeleton diseases. The bouquet-like structure of COMP allows it to act as a bridging molecule that regulates cellular phenotype and function. COMP is able to interact with many other ECM components and binds directly to a variety of cellular receptors and growth factors. The roles of COMP in other skeleton diseases, such as osteoarthritis, have been implied. As a well-established biochemical marker, COMP indicates cartilage turnover associated with destruction. Recent exciting achievements indicate its involvement in other diseases, such as malignancy, cardiovascular diseases, and tissue fibrosis. Here, we review the basic concepts of COMP and summarize its novel functions in the regulation of signaling events. These findings renew our understanding that COMP has a notable function in cell behavior and disease progression as a signaling regulator. Interestingly, COMP shows distinct functions in different diseases. Targeting COMP in malignancy may withdraw its beneficial effects on the vascular system and induce or aggravate cardiovascular diseases. COMP supplementation is a promising treatment for OA and aortic aneurysms while it may induce tissue fibrosis or cancer metastasis.

Systemic Proteomic Analysis Reveals Distinct Exosomal Protein Profiles in Rheumatoid Arthritis

Objective

Rheumatoid arthritis (RA) is a complex disease with unknown pathogenesis. In recent years, fewer have paid attention to the broad spectrum of systemic markers of RA. The aim of this study was to identify exosomal candidate proteins in the pathogenesis of RA.

Methods

Totally, 12 specimens of plasma from 6 RA patients and 6 age- and gender-matched controls from the Chinese population were obtained for nanoscale liquid chromatography coupled to tandem mass spectrometry (nano-LC-MS/MS) analysis to identify exosomal profiles.

Results

A total of 278 exosomal proteins were detected. Among them, 32 proteins were significantly upregulated (FC ≥ 2.0 and P < 0.05) and 5 proteins were downregulated (FC ≤ 0.5 and P < 0.05). Bioinformatics analysis revealed that transthyretin (TTR), angiotensinogen (AGT), lipopolysaccharide-binding protein (LBP), monocyte differentiation antigen CD14 (CD14), cartilage oligomeric matrix protein (COMP), serum amyloid P (SAP/APCS), and tenascin (TNC) can interact with each other. Subsequently, these cross-linked proteins may be mainly involved in the inflammatory-related pathways to mediate the onset of RA. Noteworthy, the LBP/CD14 complex can promote the expression of IL-8 and TNF-α, eventually leading to the development of RA.

Conclusions

Our findings suggest distinct plasmatic exosomal protein profiles in RA patients. These proteins not only take important parts in the vicious circle in the pathogenic process of RA but also serve as novel biomarkers in RA diagnosis and prognosis.

Objective and noninvasive biochemical markers in rheumatoid arthritis: where are we and where are we going?

INTRODUCTION

Rheumatoid arthritis (RA) is a chronic autoimmune disease that affects approximately 1% of the adult population. RA is multi-factorial, and as such our understanding of the molecular pathways involved in the disease is currently limited. An increasing number of studies have suggested that several molecular phenotypes (i.e. endotypes) of RA exist, and that different endotypes respond differently to various treatments. Biochemical markers may be an attractive means for achieving precision medicine, as they are objective and easily obtainable.

AREAS COVERED

We searched recent publications on biochemical markers in RA as either diagnostic or prognostic markers, or as markers of disease activity. Here, we provide a narrative overview of different classes of markers, such as autoantibodies, citrulline products, markers of tissue turnover and cytokines, that have been tested in clinical cohorts or trials including RA patients.

EXPERT OPINION

Although many biochemical markers have been identified and tested, few are currently being used in clinical practice. As more treatment options are becoming available, the need for precision medicine tools that can aid physicians and patients in choosing the right treatment is growing.

The molecular mechanism study of COMP involved in the articular cartilage damage of Kashin-Beck disease

Aims

Kashin-Beck disease (KBD) is a kind of chronic osteochondropathy, thought to be caused by environmental risk factors such as T-2 toxin. However, the exact aetiology of KBD remains unclear. In this study, we explored the functional relevance and biological mechanism of cartilage oligosaccharide matrix protein (COMP) in the articular cartilage damage of KBD.

Methods

The articular cartilage specimens were collected from five KBD patients and five control subjects for cell culture. The messenger RNA (mRNA) and protein expression levels were detected by quantitative reverse transcription PCR (qRT-PCR) and western blot. The survival rate of C28/I2 chondrocyte cell line was detected by MTT assay after T-2 toxin intervention. The cell viability and mRNA expression levels of apoptosis related genes between COMP-overexpression groups and control groups were examined after cell transfection.

Results

The mRNA and protein expression levels of COMP were significantly lower in KBD chondrocytes than control chondrocytes. After the T-2 toxin intervention, the COMP mRNA expression of C28/I2 chondrocyte reduced and the protein level of COMP in three intervention groups was significantly lower than in the control group. MTT assay showed that the survival rate of COMP overexpression KBD chondrocytes were notably higher than in the blank control group. The mRNA expression levels of Survivin, SOX9, Caspase-3, and type II collagen were also significantly different among COMP overexpression, negative control, and blank control groups.

Conclusion

Our study results confirmed the functional relevance of COMP with KBD. COMP may play an important role in the excessive chondrocytes apoptosis of KBD patients.Cite this article: Bone Joint Res 2020;9(9):578-586.

The quest for substrates and binding partners: A critical barrier for understanding the role of ADAMTS proteases in musculoskeletal development and disease

Secreted ADAMTS metalloproteases are involved in the sculpting, remodeling, and erosion of connective tissues throughout the body, including in the musculoskeletal system. ADAMTS proteases contribute to musculoskeletal development, pathological tissue destruction, and are mutated in congenital musculoskeletal disorders. Examples include versican cleavage by ADAMTS9 which is required for interdigital web regression during limb development, ADAMTS5-mediated aggrecan degradation in osteoarthritis resulting in joint erosion, and mutations in ADAMTS10 or ADAMTS17 that cause Weill-Marchesani syndrome, a short stature syndrome with bone, joint, muscle, cardiac, and eye involvement. Since the function of ADAMTS proteases and proteases in general is primarily defined by the molecular consequences of proteolysis of their respective substrates, it is paramount to identify all physiological substrates for each individual ADAMTS protease. Here, we review the current knowledge of ADAMTS proteases and their involvement in musculoskeletal development and disease, focusing on some of their known physiological substrates and the consequences of substrate cleavage. We further emphasize the critical need for the identification and validation of novel ADAMTS substrates and binding partners by describing the principles of mass spectrometry-based approaches and by emphasizing strategies that need to be considered for validating the physiological relevance for ADAMTS-mediated proteolysis of novel putative substrates.

RNA-seq reveals downregulated osteochondral genes potentially related to tibia bacterial chondronecrosis with osteomyelitis in broilers

Background

Bacterial chondronecrosis with osteomyelitis (BCO) develops in the growth plate (GP) of the proximal femur and tibia and is initiated by damage to the less mineralized chondrocytes followed by colonization of opportunistic bacteria. This condition affects approximately 1% of all birds housed, being considered one of the major causes of lameness in fast growing broilers. Although several studies have been previously performed aiming to understand its pathogenesis, the molecular mechanisms involved with BCO remains to be elucidated. Therefore, this study aimed to generate a profile of global differential gene expression involved with BCO in the tibia of commercial broilers, through RNA sequencing analysis to identity genes and molecular pathways involved with BCO in chickens.

Results

Our data showed 192 differentially expressed (DE) genes: 63 upregulated and 129 downregulated in the GP of the tibia proximal epiphysis of BCO-affected broilers. Using all DE genes, six Biological Processes (BP) were associated with bone development (connective tissue development, cartilage development, skeletal system development, organ morphogenesis, system development and skeletal system morphogenesis). The analyses of the upregulated genes did not indicate any significant BP (FDR < 0.05). However, with the downregulated genes, the same BP were identified when using all DE genes in the analysis, with a total of 26 coding genes explaining BCO in the tibia: ACAN, ALDH1A2, CDH7, CHAD, CHADL, COL11A1, COMP, CSGALNACT1, CYR61, FRZB, GAL3ST1, HAPLN1, IHH, KIF26B, LECT1, LPPR1, PDE6B, RBP4A, SERINC5, SFRP1, SOX8, SOX9, TENM2, THBS1, UCHL1 and WFIKKN2. In addition, seven transcription factors were also associated to BCO: NFATC2, MAFB, HIF1A-ARNT, EWSR1-FLI1, NFIC, TCF3 and NF-KAPPAB.

Conclusions

Our data show that osteochondral downregulated genes are potential molecular causes of BCO in broilers, and the bacterial process seems to be, in fact, a secondary condition. Sixteen genes responsible for bone and cartilage formation were downregulated in BCO-affected broilers being strong candidate genes to trigger this disorder.

Elevated serum cartilage oligomeric matrix protein and the metalloproteinase-ADAMTS7 levels are associated with vascular calcification in maintenance hemodialysis patients

BACKGROUND

Vascular calcification is common in maintenance hemodialysis (HD) patients. Recent studies showed that cartilage oligomeric matrix protein (COMP) could protect blood vessels from calcification, but the role of ADAMTS7 was opposite. We aimed to investigate the relationship between serum COMP, ADAMTS7 levels and vascular calcification scores in HD patients.

METHODS

Serum COMP and ADAMTS7 levels were tested by ELISA and we compared calcification scores between high and low COMP groups, also between high and low ADAMTS7 groups. We also investigated the differences of serum COMP and ADAMTS7 levels between mild and severe vascular calcification groups. The relationship between serum COMP and ADAMTS7 levels was analyzed in the end.

RESULTS

Serum COMP and ADAMTS7 levels were both higher in HD patients than in control (29.63 vs 14.23 ng/mL, P = .002, 11.12 vs 2.40 ng/mL, P = .005). Serum COMP levels in severe vascular calcification (VC) group were higher than in mild VC (43.13 ± 28.77 vs 26.75 ± 18.22 ng/mL, P = .010). Serum ADAMTS7 levels were positively correlated with radial and digital arteries (small arteries) calcification scores (r = .249, P = .033). And serum COMP and ADAMTS7 levels were positively correlated (r = .348, P = .026).

CONCLUSIONS

Serum COMP and ADAMTS7 levels were probably associated with vascular calcification scores in HD respectively.