Mass spectrometry-based proteomics identify novel serum osteoarthritis biomarkers

Abstract

Background Osteoarthritis (OA) is a slowly developing and debilitating disease, and there are no validated specific biomarkers for its early detection. To improve therapeutic approaches, identification of specific molecules/biomarkers enabling early determination of this disease is needed. This study aimed at identifying, with the use of proteomics/mass spectrometry, novel OA-specific serum biomarkers. As obesity is a major risk factor for OA, we discriminated obesity-regulated proteins to target only OA-specific proteins as biomarkers. Methods Serum from the Osteoarthritis Initiative cohort was used and divided into 3 groups: controls (n=8), OA-obese (n=10) and OA-non-obese (n=10). Proteins were identified and quantified from the liquid chromatography–tandem mass spectrometry analyses using MaxQuant software. Statistical analysis used the Limma test followed by the Benjamini-Hochberg method. To compare the proteomic profiles, the multivariate unsupervised principal component analysis (PCA) followed by the pairwise comparison was used. To select the most predictive/discriminative features, the supervised linear classification model sparse partial least squares regression discriminant analysis (sPLS-DA) was employed. Validation of three differential proteins was performed with protein-specific assays using plasma from a cohort derived from the Newfoundland Osteoarthritis. Results In total, 509 proteins were identified, and 279 proteins were quantified. PCA-pairwise differential comparisons between the 3 groups revealed that 8 proteins were differentially regulated between the OA-obese and/or OA-non-obese with controls. Further experiments using the sPLS-DA revealed two components discriminating OA from controls (component 1, 9 proteins), and OA-obese from OA-non-obese (component 2, 23 proteins). Proteins from component 2 were considered related to obesity. In component 1, compared to controls, 7 proteins were significantly upregulated by both OA groups and 2 by the OA-obese. Among upregulated proteins from both OA groups, some of them alone would not be a suitable choice as specific OA biomarkers due to their rather non-specific role or their strong link to other pathological conditions. Altogether, data revealed that the protein CRTAC1 appears to be a strong OA biomarker candidate. Other potential new biomarker candidates are the proteins FBN1, VDBP, and possibly SERPINF1. Validation experiments revealed statistical differences between controls and OA for FBN1 (p=0.044) and VDPB (p=0.022), and a trend for SERPINF1 (p=0.064). Conclusion Our study suggests that 4 proteins, CRTAC1, FBN1, VDBP, and possibly SERPINF1, warrant further investigation as potential new biomarker candidates for the whole OA population.

Decreased plasma cartilage acidic protein 1 in COVID‐19

“…We found no correlations between CRTAC1 concentrations and the domains of the SF-36 health survey. Determination of the reasons behind and significance of decreased CRTAC1 concentration in a subset of post-COVID-19 patients will require more detailed analysis of the roles of age, nature, and timing of the episode of COVID-19, and conditions that drive plasma CRTAC1 concentration up, such as osteoarthritis (Styrkarsdottir et al, 2021(Styrkarsdottir et al, , 2023Szilagyi et al, 2023;Tardif et al, 2022), or down, such idiopathic pulmonary fibrosis (Mayr et al, 2021) or COPD (this study). Importantly, longitudinal studies of CRTAC1 concentrations are needed post-COVID-19 in patients with and without symptoms of long COVID.…”

“…Joint tissues contribute significantly to plasma CRTAC1 concentration as demonstrated by population-wide proteomic studies that associate higher plasma CRTAC1 concentrations with severity and progression of osteoarthritis (Styrkarsdottir et al, 2021(Styrkarsdottir et al, , 2023Szilagyi et al, 2023). Indeed, in a small intensity-based mass spectrometric study, a 5.5-fold increase in CRTAC1 was found in osteoarthritis patients versus controls (Tardif et al, 2022). In addition, CRTAC1 production by T2AE cells would need to be lost almost completely to explain the extremely low CRTAC1 levels.…”

Cartilage Acidic Protein 1 in Plasma Associates With Prevalent Osteoarthritis and Predicts Future Risk as Well as Progression to Joint Replacements: Results From the UK Biobank Resource

“…We had previously also shown a high correlation between CRTAC1 levels in the SomaScan and Olink Target assays (1), and recently, CRTAC1 was confirmed as a biomarker for OA severity and progression using the Olink Target assay (6). Furthermore, CRTAC1 was recently found to be a potential OA biomarker candidate using a mass spectrometry platform (8). Thus, several different protein assay platforms seem to capture CRTAC1 protein levels in plasma with similar results.…”

A “best-in-class” systemic biomarker predictor of clinically relevant knee osteoarthritis structural and pain progression

“…In addition, in the Rotterdam cohort in models adjusted for age, sex, and BMI, serum CRAC1 has been identified as a biomarker of overall radiographic OA severity (hand, hip, and knee OA combined) and knee radiographic OA severity and progression (25). Last, in a recent untargeted MS study of serum (26), CRAC1, along with fibrillin-1 (FBN1), and VTDB (all elevated above control) were identified as knee OA-related proteins; CRAC1 was the strongest contributor to a principal component (PC) discriminating OA from control, underscoring its emerging importance as a robust knee OArelated biomarker.…”