Abstract
Background: The purpose of this study was to determine whether plasma levels of the collagen triple helix repeat containing 1 (CTHRC1) protein can serve as a blood-based biomarker for improved diagnosis of rheumatoid arthritis (RA) patients and monitoring of RA disease activity.Methods: We measured levels of CTHRC1 in the plasma of patients diagnosed with RA, osteoarthritis (OA), reactive arthritis (ReA), as well as in healthy individuals. We then assessed the correlation between CTHRC1 protein and a range of indices including the 28-joint disease activity score (DAS28), rheumatoid factor (RF), C-reactive protein (CRP), anti-citrullinated protein antibodies (ACPA), erythrocyte sedimentation rate (ESR), as well as a panel of cytokines, including interleukin 1 beta (IL-1β), interleukin 6 (IL-6), interleukin 8 (IL-8), and interferon gamma (IFNγ). Receiver operating characteristic (ROC) analysis was further performed to assess the diagnostic value of CTHRC1.Results: CTHRC1 plasma levels were significantly elevated in RA patients compared to healthy individuals, OA and ReA patients. ROC curve and risk score analysis suggested that plasma CTHRC1 can accurately discriminate patients with RA from healthy controls and may have practical value for RA diagnosis. CTHRC1 levels were positively associated with RF, ACPA, CRP, and disease activity based on the combined index of DAS28 with CRP (DAS28-CRP), and also strongly correlated with IL-1β, IL-6, IL-8, and IFNγ.Conclusion: Our studies show that CTHRC1 is a sensitive and easy-to-measure plasma marker that differentiates between RA and healthy status and also distinguishes between RA and other forms of arthritis, such as OA and ReA. At the current level of understanding, plasma CTHRC1 levels may improve the diagnosis of RA and these findings warrant confirmation in a larger, more comprehensive patient population.
Highlights
The purpose of this study was to determine whether plasma levels of the collagen triple helix repeat containing 1 (CTHRC1) protein can serve as a blood-based biomarker for improved diagnosis of rheumatoid arthritis (RA) patients and monitoring of RA disease activity
We recently reported that increased levels of collagen triple helix repeat containing 1 protein (CTHRC1) are strongly associated with the severity of murine proteoglycan-induced arthritis and collagen antibody-induced murine arthritis (CAIA) [24,25,26,27]
Other subgroups of RA patients were treated with methotrexate in combination with glucocorticoids (MTx+GC, 17.5%, Table 2), methotrexate in combination with other synthetic Disease-modifying anti-rheumatic drugs (DMARDs) (MTx+DMARD, 5.25%, Table 2), or methotrexate with other treatments (NSAIDs plus synthetic DMARDs, with or without ibandronate; MTx+, 3.5%, Table 2). 3.5% of patients received glucocorticoids alone, whereas leflunomide or hydroxychloroquine alone or in combination were prescribed for an additional 3.5% of patients (DMARD, Table 2). 1.75% of patients were treated with a combination of methotrexate and non-steroidal anti-inflammatory drugs (MTX+NSAIDs, Table 2)
Summary
The purpose of this study was to determine whether plasma levels of the collagen triple helix repeat containing 1 (CTHRC1) protein can serve as a blood-based biomarker for improved diagnosis of rheumatoid arthritis (RA) patients and monitoring of RA disease activity. Disease progression is characterized by periods of flares with high disease activity involving both, a systemic immune response and tissue-specific inflammatory events that can lead to erosive joint and bone destruction and subsequent disability [1, 2]. Mounting evidence indicates that early RA diagnosis and treatment aimed at controlling disease activity is essential in halting or delaying progression to erosive disease [1, 3]. This so-called “treat-to-target” strategy relies on accurate diagnosis of patients early in the disease course and frequent monitoring of disease activity thereafter in order to guide and optimize treatment to achieve remission or a low disease activity state [1, 3]. There is mounting evidence that the heterogeneity of RA reflects genetic and biological differences and that multiple molecularly distinct RA subtypes may exist, which differ in their underlying disease mechanisms [11,12,13]
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