A genetic association study of serum acute-phase C-reactive protein levels in rheumatoid arthritis: implications for clinical interpretation

Soluble signal inhibitory receptor on leukocytes-1 reflects disease activity and assists diagnosis of patients with rheumatoid arthritis

BACKGROUND

SIRL-1, an immunosuppressive receptor encoded by the VSTM1 gene, has recently been linked to rheumatoid arthritis (RA) due to its association with activated polymorphonuclear neutrophils (PMNs). Considering that the activated PMNs play a crucial role in the pathogenesis of rheumatoid arthritis (RA), we aimed to measure the levels of soluble SIRL-1, investigating whether they add value to RA in the clinical diagnosis.

METHODS

Utilizing an enzyme-linked immunosorbent assay, the concentration of sSIRL-1 was measured in serum samples from cohort 1 diagnosed with RA (n = 96), gout (n = 54), osteoarthritis (n = 47), healthy controls (n = 86) and synovial fluid samples from OA (n = 8) and RA (n = 8) patients, respectively. Additionally, an external validation in cohort 2 (n = 156) comprising various inflammatory diseases was employed.

RESULTS

The study revealed a distinctive upregulation of sSIRL-1 in the serum of RA compared to HC and other arthralgia diseases (p < 0.0001), which also displayed a significant elevation in synovial fluid from RA compared to OA (p < 0.05). Notably, sSIRL-1 levels exhibited a significant decrease in patients who achieved disease remission (p < 0.05). Furthermore, the diagnostic accuracy of RA was enhanced when sSIRL-1 was combined with anti-CCP and RF, yielding an impressive AUC value of 0.950.

CONCLUSION

The expression pattern of sSIRL-1 in RA, coupled with its correlation with disease activity, underscores its potential clinical utility for both diagnosis and disease monitoring in RA patients. This study offers valuable insights into the evolving diagnostic landscape of RA.

Exosomes as Rheumatoid Arthritis Diagnostic Biomarkers and Therapeutic Agents

Rheumatoid arthritis (RA) is a chronic inflammatory joint disorder that causes systemic inflammation, autoimmunity, and joint abnormalities that result in permanent disability. Exosomes are nanosized extracellular particles found in mammals (40–100 nm). They are a transporter of lipids, proteins, and genetic material involved in mammalian cell–cell signaling, biological processes, and cell signaling. Exosomes have been identified as playing a role in rheumatoid arthritis-related joint inflammation (RA). Uniquely functioning extracellular vesicles (EVs) are responsible for the transport of autoantigens and mediators between distant cells. In addition, paracrine factors, such as exosomes, modulate the immunomodulatory function of mesenchymal stem cells (MSCs). In addition to transporting genetic information, exosomes convey miRNAs between cells and have been studied as drug delivery vehicles. In animal models, it has been observed that MSCs secrete EVs with immunomodulatory properties, and promising results have been observed in this area. By understanding the diversity of exosomal contents and their corresponding targets, it may be possible to diagnose autoimmune diseases. Exosomes can be employed as diagnostic biomarkers for immunological disorders. We here discuss the most recent findings regarding the diagnostic, prognostic, and therapeutic potential of these nanoparticles in rheumatoid arthritis and provide an overview of the evidence pertaining to the biology of exosomes in RA.

Exploring the role of exosomes in rheumatoid arthritis

In prosperous countries, autoimmune illnesses affect minimum 7% of the community. Rheumatoid Arthritis (RA) as an autoimmune illness is thought to be induced through a variety of genomic, physiological, and biological factors. Many experts in the field of nanomedicine have looked to stem cells as a viable strategy to repair human tissue; however, exosomes have demonstrated greater potential in recent years. Exosomes, produced from stem cells in particular, have exhibited a high propensity to give therapeutic effects. To resist local cellular stress, they are secreted in a paracrine manner from cells. As a result, exosomes produced from stem cells can provide enormous health uses. If treatment is not given, autoantibodies produce synovial inflammation and arthritis, which can lead to chronic inflammation, and impairment. Exosomes could be administered for the treatment of RA, by acting as therapeutic vectors. Exosomes are murine extracellular vesicles that influence biological mechanisms and signal transduction by transporting genetic and protein components. Diseases like RA and bone fractures could be treated using cell-free therapeutic strategies if exosomes could be isolated from stem cells efficiently and packaged with specific restorative substances. To get to this position, many breakthroughs must be achieved, and the following review summarises the most recent developments in stem cell-derived exosomes, with a focus on the important literature on exosome dynamics in RA.

Correlation of CRP genotypes with serum CRP levels and the risk of rheumatoid arthritis in Chinese Han population

OBJECTIVE

C-reactive protein (CRP) is an important index for evaluating the disease activity of rheumatoid arthritis (RA). CRP may play a direct role in bone destruction in RA. Studies have demonstrated that serum CRP levels had a close correlation with tissue inflammation scores in patients with RA. In addition, genetic factors play a crucial role in the development of RA. In this study, we aimed to investigate the relationship between the CRP gene variants (rs1205 polymorphism) and the risk of RA in Chinese Han population.

METHODS

502 RA patients and 581 controls were included in this study. The associations between CRP gene variants and CRP levels and RA risk were investigated.

RESULTS

We found that TT/ TT + CT genotype was significantly related with an increased risk of RA (TT vs CC: OR, 1.56, 95%CI, 1.01-2.40, P = 0.045; TT + CT vs CC: OR, 1.30, 95%CI, 1.02-1.65, P = 0.032). In addition, T allele was shown to associate with an elevated risk of RA. After subgroup analysis, we found that rs1205 polymorphism was significantly related with an enhanced risk of RA among females, individuals lower than 60 years, and subjects with a BMI > 25 kg/m². Furthermore, data showed that the CRP gene rs1205 polymorphism correlated with CRP and ESR levels. Furthermore, the TT genotype was significantly associated with a reduction of CRP levels compared with CT or CC genotype.

CONCLUSIONS

To sum up, this study reveals that rs1205 polymorphism of the CRP gene is related with an increased risk of RA and CRP levels in Chinese Han population. Key Points • The CRP gene rs1205 polymorphism is related with a higher risk of RA. • The CRP gene rs1205 polymorphism correlates with CRP and ESR levels. • The TT genotype of rs1205 polymorphism is linked with a reduction of CRP levels.

YWHAH Genetic Variants are Associated with Increased Hypoxia Inducible Factor-1α/Vascular Endothelial Growth Factor in Egyptian Rheumatoid Arthritis Patients

The 14-3-3 Eta (14-3-3 η) biomarker platform is a relatively recent discovery with the potential to significantly address the diagnosis and prognosis of rheumatoid arthritis (RA) disease. Hypoxia-inducible factor (HIF)-1α and vascular endothelial growth factor (VEGF) have been implicated in inflammatory mechanisms in RA. We hypothesized a molecular association of the coding YWHAH gene and its expressed protein 14-3-3 η with hypoxia and angiogenesis in RA. One hundred healthy subjects and 100 RA patients were enrolled in the study. YWHAH gene expression was determined using quantitative PCR, and its gene polymorphism rs2858750 was assessed by Taqman genotyping assay. Serum levels of 14-3-3 η, HIF-1α, and VEGF were measured using the ELISA technique, and clinical parameters were routinely examined. In RA patients, significant positive correlations were found between 14-3-3 η, HIF-1α (r = 0.84), and VEGF (r = 0.85). YWHAH gene expression was upregulated 10.8 fold (CI 95% 10.1-11.5) in RA patients and significantly correlated with all disease activity parameters, ACPA, and levels of 14-3-3 η, HIF-1α, and VEGF. RA patients showed a higher frequency of YWHAH rs2858750 A allele than healthy subjects (p = 0.02). The risk A allele carriers showed higher disease activity parameters, ACPA, YWHAH gene expression, and increased serum levels of 14-3-3 η (p < 0.001), HIF-1α (p = 0.002), and VEGF (p = 0.001) than the G allele. Serum 14-3-3 η and its rs2858750 genetic variant are associated with increased hypoxia and angiogenesis in RA and activity, and severity of the disease.

C-Reactive Protein Knockout Attenuates Temporomandibular Joint Inflammation in Rats

BACKGROUND

C-reactive protein (CRP), a biomarker of inflammation, is highly expressed in osteoarthritis- (OA-) related diseases, but its exact role remains unknown. In this study, we evaluated the biological effect of CRP on temporomandibular joint (TMJ) inflammation.

METHODS

Freund's complete adjuvant (CFA) was used to induce TMJ inflammation in CRP-knockout (CRP-/-) and control rats. Degenerative changes in the TMJ were compared to elucidate the role of CRP in TMJ inflammation. In addition, inflammatory cytokines, macrophage activation, and osteoclast differentiation were evaluated by real-time quantitative polymerase chain reaction, immunohistochemistry, and tartrate-resistant phosphatase staining to explore the potential regulatory mechanism.

RESULTS

Compared to the control, CFA induced TMJ inflammation, which increased systemic and local CRP expression. Furthermore, CRP-/- rats exhibited less severe inflammatory symptoms. The downregulation of proinflammatory cytokines (interleukin- (IL-) 1β and IL-6) and upregulation of the anti-inflammatory cytokine IL-10 were detected in CRP-/- rats, which also exhibited reduced macrophage activation and osteoclast differentiation.

CONCLUSION

These results indicated that controlling the highly elevated levels of CRP during inflammation could modify the cytokine profile, macrophage activation, and osteoclast differentiation, thus, providing beneficial effects for TMJ-OA prevention and treatment.

Genetically Determined Chronic Low-Grade Inflammation and Hundreds of Health Outcomes in the UK Biobank and the FinnGen Population: A Phenome-Wide Mendelian Randomization Study

Background

C-reactive protein (CRP) has been used as a biomarker of chronic low-grade inflammation in observational studies. We aimed to determine whether genetically determined CRP was associated with hundreds of human phenotypes to guide anti-inflammatory interventions.

Methods

We used individual data from the UK Biobank to perform a phenome-wide two-stage least squares (2SLS) Mendelian randomization (MR) analysis for CRP with 879 diseases. Summary-level data from the FinnGen consortium were utilized to perform phenome-wide two-sample MR analysis on 821 phenotypes. Systematic two-sample MR methods included MR-IVW, MR-WME, MR-Mod, and MR-PRESSO as sensitivity analyses combined with multivariable MR to identify robust associations. Genetic correlation analysis was applied to identify shared genetic risks.

Results

We found genetically determined CRP was robustly associated with 15 diseases in the UK Biobank and 11 diseases in the FinnGen population (P < 0.05 for all MR analyses). CRP was positively associated with tongue cancer, bronchitis, hydronephrosis, and acute pancreatitis and negatively associated with colorectal cancer, colon cancer, cerebral ischemia, electrolyte imbalance, Parkinson's disease, epilepsy, anemia of chronic disease, encephalitis, psychophysical visual disturbances, and aseptic necrosis of bone in the UK Biobank. There were positive associations with impetigo, vascular dementia, bipolar disorders, hypercholesterolemia, vertigo, and neurological diseases, and negative correlations with degenerative macular diseases, metatarsalgia, interstitial lung disease, and idiopathic pulmonary fibrosis, and others. in the FinnGen population. The electrolyte imbalance and anemia of chronic disease in UK Biobank and hypercholesterolemia and neurological diseases in FinnGen pass the FDR corrections. Neurological diseases and bipolar disorders also presented positive genetic correlations with CRP. We found no overlapping causal associations between the populations. Previous causal evidence also failed to support these associations (except for bipolar disorders).

Conclusions

Genetically determined CRP was robustly associated with several diseases in the UK Biobank and the FinnGen population, but could not be replicated, suggesting heterogeneous and non-repeatable effects of CRP across populations. This implies that interventions at CRP are unlikely to result in decreased risk for most human diseases in the general population but may benefit specific high-risk populations. The limited causal evidence and potential double-sided effects remind us to be cautious about CRP interventions.

Quantile-dependent expressivity of serum C-reactive protein concentrations in family sets

Background

“Quantile-dependent expressivity” occurs when the effect size of a genetic variant depends upon whether the phenotype (e.g., C-reactive protein, CRP) is high or low relative to its distribution. We have previously shown that the heritabilities (h²) of coffee and alcohol consumption, postprandial lipemia, lipoproteins, leptin, adiponectin, adiposity, and pulmonary function are quantile-specific. Whether CRP heritability is quantile-specific is currently unknown.

Methods

Serum CRP concentrations from 2,036 sibships and 6,144 offspring-parent pairs were analyzed from the Framingham Heart Study. Quantile-specific heritability from full-sib (β_FS, h² ={(1 + 8r_spouseβ_FS)^0.5 − 1}/(2r_spouse)) and offspring-parent regression slopes (β_OP, h² = 2β_OP/(1 + r_spouse)) were estimated robustly by quantile regression with nonparametric significance determined from 1,000 bootstrap samples.

Results

Quantile-specific h² (±SE) increased with increasing percentiles of the offspring’s age- and sex-adjusted CRP distribution when estimated from β_OP (P_trend = 0.0004): 0.02 ± 0.01 at the 10th, 0.04 ± 0.01 at the 25th, 0.10 ± 0.02 at the 50th, 0.20 ± 0.05 at the 75th, and 0.33 ± 0.10 at the 90th percentile, and when estimated from β_FS (P_trend = 0.0008): 0.03±0.01 at the 10th, 0.06 ± 0.02 at the 25th, 0.14 ± 0.03 at the 50th, 0.24 ± 0.05 at the 75th, and 0.53 ± 0.21 at the 90th percentile.

Conclusion

Heritability of serum CRP concentration is quantile-specific, which may explain or contribute to the inflated CRP differences between CRP (rs1130864, rs1205, rs1800947, rs2794521, rs3091244), FGB (rs1800787), IL-6 (rs1800795, rs1800796), IL6R (rs8192284), TNF-α (rs1800629) and APOE genotypes following CABG surgery, stroke, TIA, curative esophagectomy, intensive periodontal therapy, or acute exercise; during acute coronary syndrome or Staphylococcus aureus bacteremia; or in patients with chronic rheumatoid arthritis, diabetes, peripheral arterial disease, ankylosing spondylitis, obesity or inflammatory bowel disease or who smoke.

Global assessment of C-reactive protein and health-related outcomes: an umbrella review of evidence from observational studies and Mendelian randomization studies

C-reactive protein (CRP) has been studied extensively for association with a large number of non-infectious diseases and outcomes. We aimed to evaluate the breadth and validity of associations between CRP and non-infectious, chronic health outcomes and biomarkers. We conducted an umbrella review of systematic reviews and meta-analyses and a systematic review of Mendelian randomization (MR) studies. PubMed, Scopus, and Cochrane Database of Systematic Reviews were systematically searched from inception up to March 2019. Meta-analyses of observational studies and MR studies examining associations between CRP and health outcomes were identified, excluding studies on the diagnostic value of CRP for infections. We found 113 meta-analytic comparisons of observational studies and 196 MR analyses, covering a wide range of outcomes. The overwhelming majority of the meta-analyses of observational studies reported a nominally statistically significant result (95/113, 84.1%); however, the majority of the meta-analyses displayed substantial heterogeneity (47.8%), small study effects (39.8%) or excess significance (41.6%). Only two outcomes, cardiovascular mortality and venous thromboembolism, showed convincing evidence of association with CRP levels. When examining the MR literature, we found MR studies for 53/113 outcomes examined in the observational study meta-analyses but substantial support for a causal association with CRP was not observed for any phenotype. Despite the striking amount of research on CRP, convincing evidence for associations and causal effects is remarkably limited.

A pilot study of a machine-learning tool to assist in the diagnosis of hand arthritis

OBJECTIVE

Arthritis is a common condition, which frequently involves the hands. Patients with inflammatory arthritis have been shown to experience significant delays in diagnosis. We sought to develop and test a screening tool combining an image of a patient's hands, a short series of questions, and a single examination technique, to determine the most likely diagnosis in a patient presenting with hand arthritis. Machine learning techniques were used to develop separate algorithms for each component, which were combined to produce a diagnosis.

METHODS

280 consecutive new patients presenting to a Rheumatology practice with hand arthritis were enrolled. Each patient completed a 9-part questionnaire, had photographs taken of each hand, and had a single examination result recorded. The Rheumatologist diagnosis was recorded following a 45-minute consultation. The photograph algorithm was developed from 1000 previous hand images, and machine learning techniques were applied to the questionnaire results, training several models against the diagnosis from the Rheumatologist.

RESULTS

The combined algorithms in this study were able to predict inflammatory arthritis with an accuracy, precision, recall and specificity of 96·8%, 97·2%, 98·6% and 90·5% respectively. Similar results were found when inflammatory arthritis was subclassified into rheumatoid arthritis and psoriatic arthritis. The corresponding figures for osteoarthritis were 79·6%, 85·9%, 61·9% and 92·6%.

CONCLUSION

This study demonstrates a novel application combining image-processing and a patient questionnaire with applied machine-learning methods, to facilitate the diagnosis of patients presenting with hand arthritis. Preliminary results are encouraging for the application of such techniques in clinical practice. This article is protected by copyright. All rights reserved.

C-reactive protein and implications in rheumatoid arthritis and associated comorbidities

C-reactive protein (CRP) is routinely assessed as a marker of systemic inflammation in rheumatoid arthritis (RA). However, it is also an immune regulator that plays an important role in inflammatory pathways associated with RA and promotes atherogenic effects. Comorbidities linked to systemic inflammation are common in RA, and CRP has been associated with the risk for cardiovascular disease, diabetes, metabolic syndrome, pulmonary diseases, and depression. The relationship between systemic inflammation, CRP, and comorbidities in RA is complex, and it is challenging to determine how changing CRP levels may affect the risk or progression of these comorbidities. We review the biological role of CRP in RA and its implications for disease activity and treatment response. We also discuss the impact of treatment on CRP levels and whether reducing systemic inflammation and inhibiting CRP-mediated inflammatory pathways may have an impact on conditions commonly comorbid with RA.

A double-blind, placebo-controlled, phase II, randomized study of lovastatin therapy in the treatment of mildly active rheumatoid arthritis

OBJECTIVES

3-hydroxy-3-methylglutaryl coenzyme-A (HMG Co-A) reductase inhibitors (statins) are standard treatment for hyperlipidaemia. In addition to lipid-lowering abilities, statins exhibit multiple anti-inflammatory effects. The objectives of this study were to determine whether treatment of patients with RA with lovastatin decreased CRP or reduced disease activity.

METHODS

We conducted a randomized double-blind placebo-controlled 12 week trial of lovastatin vs placebo in 64 RA patients with mild clinical disease activity but an elevated CRP. The primary efficacy end point was the reduction in mean log CRP. Secondary end points included disease activity, RF and anti-CCP antibody titres. Mechanistic end points included levels of serum cytokines. Safety was assessed; hepatic and muscle toxicities were of particular interest.

RESULTS

Baseline features were similar between groups. No significant difference in mean log CRP reduction between the two groups was observed, and disease activity did not change from baseline in either treatment group. Mechanistic analyses did not reveal significant changes in any biomarkers. A post hoc analysis of subjects not using biologic therapy demonstrated a significantly greater proportion achieving ⩾20% reduction in CRP from baseline in the lovastatin group compared with placebo (P-value = 0.007). No difference was observed in subjects receiving biologics. Lovastatin was well tolerated with no serious safety concerns.

CONCLUSION

This study showed no anti-inflammatory or clinical effects on RA disease activity after 12 weeks of treatment with lovastatin. Lovastatin had a modest effect on CRP in subjects not using biologics, suggesting statins may be anti-inflammatory in selected patients.

TRIAL REGISTRATION

ClinicalTrials.gov, http://clinicaltrials.gov, NCT00302952.

Conversion among the 28-joint count activity indices for rheumatoid arthritis

OBJECTIVE

Disease activity indices for rheumatoid arthritis (RA) are important in clinical practice and research. Although they are closely correlated, they are not in good agreement. We derived formulae to convert values from one of the four 28-joint count indices (disease activity score using erythrocyte sedimentation rate [DAS28-ESR], disease activity score using C-reactive protein [DAS28-CRP], clinical disease activity index [CDAI], and simple disease activity index [SDAI]) to any of the others.

METHODS

We obtained data from 175 patients from our RA registry with concurrent CRP and ESR and established the nature of relationships between the indices using these data. Subsequently, we developed empiric conversion formulae. Furthermore, we developed new cutoff values for classifying disease activity to minimize the disparity among indices, using an iterative method.

RESULTS

The relationships between DAS28-ESR and DAS28-CRP and between SDAI and CDAI were approximately linear; the others were quadratic. Quadratic equations approximated the relationship between DAS, SDAI, and CDAI, whereas natural logarithms function approximated the relationship between DAS28-ESR and DAS28-CRP. Patients are frequently categorized into inconsistent disease activity states with any two indices, with the disparity ranging from 9.7% to 40.6%. The new cutoff values were developed to minimize the discrepant activity state categorization, reducing the disparity range to 6.3%-32.6%.

CONCLUSION

We derived empiric formulae that connect DAS28-ESR, DAS28-CRP, SDAI, and CDAI. Moreover, we developed new cutoff values to minimize the discrepant activity state categorization with different indices.

The relationship between CRP gene polymorphism (rs2794521, rs3091244), ASDAS-CRP and ASDAS-ESR in ankylosing spondylitis

Background: We aimed to investigate the haplotypes and alleles of two variants (rs2794521 and rs3091244) in AS patients and to examine their relationship with ASDAS-CRP and ASDAS-ESR values.Methods: We evaluated 160 AS patients diagnosed according to the ASAS criteria. ASDAS-CRP and ASDAS-ESR values were calculated. ESR and CRP were examined. The restriction fragment length polymorphism (RFLP) method was used for detecting the rs2794521 and rs3091244 regions on the CRP gene.Results: As a result of the evaluation of rs2794521 gene polymorphism using PCR, TT, TC and CC genotypes were observed in 90, 81 and 9 individuals, respectively. As a result of the evaluation of rs3091244 gene polymorphism, CC, AC and TT genotypes were observed in 104, 51 and 5 individuals, respectively. T allele and C allele were found in rs2794521 gene by 75% and 25%, respectively. In addition, T allele, C allele and A allele were found in rs3091244 gene by 80%, 17% and 3%, respectively. With the help of regression equation, ASDAS-CRP level was 0.34 units higher in cases with rs3091244 C allele than cases without rs3091244 C alleles.Conclusion: CRP rs3091244 C allele may be associated with the increased relative risk for ASDAS-CRP.

Assessing prognosis and prediction of treatment response in early rheumatoid arthritis: systematic reviews

BACKGROUND

Rheumatoid arthritis (RA) is a chronic, debilitating disease associated with reduced quality of life and substantial costs. It is unclear which tests and assessment tools allow the best assessment of prognosis in people with early RA and whether or not variables predict the response of patients to different drug treatments.

OBJECTIVE

To systematically review evidence on the use of selected tests and assessment tools in patients with early RA (1) in the evaluation of a prognosis (review 1) and (2) as predictive markers of treatment response (review 2).

DATA SOURCES

Electronic databases (e.g. MEDLINE, EMBASE, The Cochrane Library, Web of Science Conference Proceedings; searched to September 2016), registers, key websites, hand-searching of reference lists of included studies and key systematic reviews and contact with experts.

STUDY SELECTION

Review 1 - primary studies on the development, external validation and impact of clinical prediction models for selected outcomes in adult early RA patients. Review 2 - primary studies on the interaction between selected baseline covariates and treatment (conventional and biological disease-modifying antirheumatic drugs) on salient outcomes in adult early RA patients.

RESULTS

Review 1 - 22 model development studies and one combined model development/external validation study reporting 39 clinical prediction models were included. Five external validation studies evaluating eight clinical prediction models for radiographic joint damage were also included. c-statistics from internal validation ranged from 0.63 to 0.87 for radiographic progression (different definitions, six studies) and 0.78 to 0.82 for the Health Assessment Questionnaire (HAQ). Predictive performance in external validations varied considerably. Three models [(1) Active controlled Study of Patients receiving Infliximab for the treatment of Rheumatoid arthritis of Early onset (ASPIRE) C-reactive protein (ASPIRE CRP), (2) ASPIRE erythrocyte sedimentation rate (ASPIRE ESR) and (3) Behandelings Strategie (BeSt)] were externally validated using the same outcome definition in more than one population. Results of the random-effects meta-analysis suggested substantial uncertainty in the expected predictive performance of models in a new sample of patients. Review 2 - 12 studies were identified. Covariates examined included anti-citrullinated protein/peptide anti-body (ACPA) status, smoking status, erosions, rheumatoid factor status, C-reactive protein level, erythrocyte sedimentation rate, swollen joint count (SJC), body mass index and vascularity of synovium on power Doppler ultrasound (PDUS). Outcomes examined included erosions/radiographic progression, disease activity, physical function and Disease Activity Score-28 remission. There was statistical evidence to suggest that ACPA status, SJC and PDUS status at baseline may be treatment effect modifiers, but not necessarily that they are prognostic of response for all treatments. Most of the results were subject to considerable uncertainty and were not statistically significant.

LIMITATIONS

The meta-analysis in review 1 was limited by the availability of only a small number of external validation studies. Studies rarely investigated the interaction between predictors and treatment.

SUGGESTED RESEARCH PRIORITIES

Collaborative research (including the use of individual participant data) is needed to further develop and externally validate the clinical prediction models. The clinical prediction models should be validated with respect to individual treatments. Future assessments of treatment by covariate interactions should follow good statistical practice.

CONCLUSIONS

Review 1 - uncertainty remains over the optimal prediction model(s) for use in clinical practice. Review 2 - in general, there was insufficient evidence that the effect of treatment depended on baseline characteristics.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42016042402.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Genetic Variation Affects C-Reactive Protein Elevations in Crohn's Disease

BACKGROUND

C-reactive protein (CRP) is a serum marker that is used to measure disease activity in Crohn's disease (CD). However, a subset of CD patients have normal CRP during flares. In rheumatoid arthritis and lupus, genetic variants can restrict CRP elevations during flares. This study sought to determine if common CRP genetic variants affect CRP values during active CD.

METHODS

Subjects with CD who participated in the Partners HealthCare BioBank were genotyped for 5 common CRP genetic variants (rs2794520, rs3122012, rs3093077, rs2808635, and rs1800947). Medical records were reviewed to determine disease activity and the highest CRP value during active CD. CRP values during active infection or malignancy at the time of the test were excluded. CRP values were compared by genotype using the Mann-Whitney test.

RESULTS

The study included 199 subjects with active CD (21 to 86 years of age). Subjects with the rs2794520 TT genotype had a lower CRP than subjects with the CC genotype (58.3 mg/L vs 28.4 mg/L, P = 0.008). Subjects with the rs1800947 CG genotype had a lower CRP than those with the CC genotype (54.3 mg/L vs 22.4 mg/L, P < 0.0001); 41.6% of TT subjects had a normal CRP compared with 24.1% of CT subjects and 16.5% of CC subjects (P = 0.041).

CONCLUSIONS

This study demonstrates that rs2794520 and rs1800947 are associated with a restriction of CRP elevations during active CD. While CRP is typically a reliable biomarker in CD, there is a subset of CD patients with a genetically determined restriction of CRP in whom other disease markers should be utilized.

Resistin polymorphisms are associated with rheumatoid arthritis susceptibility in Chinese Han subjects

Rheumatoid arthritis (RA) is a chronic systemic inflammatory disease. To date, the specific mechanisms that drive RA disease remain unknown and provide the impetus for genetic investigations into the development of RA. Researchers hope to identify gene polymorphisms that could serve as treatment targets in patients with RA. We have previously suggested that the gene encoding the pro-inflammatory adipokine resistin (RETN) may correlate with RA development. In this report, we sought to determine whether selected RETN single nucleotide polymorphisms (SNPs) are associated with RA susceptibility and clinicopathological characteristics. Four RETN SNPs (rs3745367, rs7408174, rs1862513, and rs3219175) were assessed using TaqMan genotyping in Chinese Han patients with RA and healthy controls. We found that carriers with the C allele of the RETN SNP rs7408174 as well as those with the AG allele or who had at least one A allele of the SNP rs3219175 are at greater risk of developing RA disease compared with wild-type carriers. Moreover, RA patients with the AG allele of the RETN SNP rs3219175 had higher serum C-reactive protein expression compared with controls, and these patients had a high likelihood of being on tumor necrosis factor (TNF) inhibitor therapy. This study is the first to discuss risk factors associated with RETN SNPs in RA progression in a Chinese Han population.

HLA-DRB1 Amino Acid Positions 11/13, 71, and 74 Are Associated With Inflammation Level, Disease Activity, and the Health Assessment Questionnaire Score in Patients With Inflammatory Polyarthritis

Objective

Rheumatoid arthritis (RA) susceptibility HLA–DRB1 haplotypes based on amino acid positions 11/13, 71, and 74 predict radiographic damage. The mechanism of action is unknown, but it may be mediated by inflammation. We undertook this study to systematically investigate the effect of these amino acids on nonradiographic measures of disease activity/outcomes.

Methods

We tested the association of RA susceptibility HLA–DRB1 amino acids with the C‐reactive protein (CRP) level, the tender joint count (TJC), the swollen joint count (SJC), the Disease Activity Score in 28 joints (DAS28), and the Health Assessment Questionnaire (HAQ) score in the Norfolk Arthritis Register (NOAR) and Early Rheumatoid Arthritis Study (ERAS) cohorts. Longitudinal modeling of disease activity/outcomes was performed using generalized linear latent and mixed models. Mediation analysis was performed using directed acyclic graphs to investigate the paths from genetic factors to outcome.

Results

A total of 2,158 patients were available for analysis in the NOAR cohort. Valine at position 11 showed the strongest association with the CRP level (P = 2.21 × 10⁻⁶), the SJC (P = 7.51 × 10⁻⁶), and the DAS28 (P = 0.002); it was marginally associated with the HAQ score (P = 0.044) but not with the TJC. The same amino acid and haplotype risk hierarchy observed for susceptibility and radiographic severity was observed for the CRP level and nonradiographic measures of disease activity/outcome, apart from the TJC. The results were replicated in the ERAS cohort. The effect of valine at position 11 on the SJC was mainly mediated by anti–citrullinated protein antibody status, the effect of which was mainly mediated by inflammation; however, the effect of valine at position 11 was also independent of the CRP level (P = 1.6 × 10⁻⁴).

Conclusion

Genetic markers of RA susceptibility located within HLA–DRB1 determine the levels of clinical and systemic inflammation independently, and also determine all objective measures of disease activity and outcome.

Cytotoxic T-lymphocyte-associated protein 4 gene polymorphism is related to rheumatoid arthritis in Egyptian population

CONTEXT

Cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) is a CD28-family receptor expressed on T-cells which suppresses T cell proliferation. CTLA-4 -318C/T polymorphism is involved in regulation of CTLA-4 expression.

OBJECTIVE

The study aimed to investigate the genetic association of CTLA-4 -318C/T polymorphism with rheumatoid arthritis (RA) and the activity and severity of the disease in the Egyptian population.

METHODS

A single nucleotide polymorphism (rs5742909) in CTLA-4 was genotyped in 100 RA patients and 100 healthy controls using polymerase chain reaction-restriction fragment length polymorphism. Diagnostic tests were measured for RA patients.

RESULTS

The frequency of T allele in RA patients was significantly higher than in the control subjects (p = 0.002). CT and TT genotypes had high C-reactive protein, erythrocyte sedimentation rate and disease activity score 28 while CC genotype had a high rheumatoid factor.

CONCLUSION

A minor allele of CTLA-4 rs5742909 polymorphism was associated with RA and the activity but not the severity of the disease.

Investigating the Causal Relationship of C-Reactive Protein with 32 Complex Somatic and Psychiatric Outcomes: A Large-Scale Cross-Consortium Mendelian Randomization Study

BACKGROUND

C-reactive protein (CRP) is associated with immune, cardiometabolic, and psychiatric traits and diseases. Yet it is inconclusive whether these associations are causal.

METHODS AND FINDINGS

We performed Mendelian randomization (MR) analyses using two genetic risk scores (GRSs) as instrumental variables (IVs). The first GRS consisted of four single nucleotide polymorphisms (SNPs) in the CRP gene (GRSCRP), and the second consisted of 18 SNPs that were significantly associated with CRP levels in the largest genome-wide association study (GWAS) to date (GRSGWAS). To optimize power, we used summary statistics from GWAS consortia and tested the association of these two GRSs with 32 complex somatic and psychiatric outcomes, with up to 123,865 participants per outcome from populations of European ancestry. We performed heterogeneity tests to disentangle the pleiotropic effect of IVs. A Bonferroni-corrected significance level of less than 0.0016 was considered statistically significant. An observed p-value equal to or less than 0.05 was considered nominally significant evidence for a potential causal association, yet to be confirmed. The strengths (F-statistics) of the IVs were 31.92-3,761.29 and 82.32-9,403.21 for GRSCRP and GRSGWAS, respectively. CRP GRSGWAS showed a statistically significant protective relationship of a 10% genetically elevated CRP level with the risk of schizophrenia (odds ratio [OR] 0.86 [95% CI 0.79-0.94]; p < 0.001). We validated this finding with individual-level genotype data from the schizophrenia GWAS (OR 0.96 [95% CI 0.94-0.98]; p < 1.72 × 10-6). Further, we found that a standardized CRP polygenic risk score (CRPPRS) at p-value thresholds of 1 × 10-4, 0.001, 0.01, 0.05, and 0.1 using individual-level data also showed a protective effect (OR < 1.00) against schizophrenia; the first CRPPRS (built of SNPs with p < 1 × 10-4) showed a statistically significant (p < 2.45 × 10-4) protective effect with an OR of 0.97 (95% CI 0.95-0.99). The CRP GRSGWAS showed that a 10% increase in genetically determined CRP level was significantly associated with coronary artery disease (OR 0.88 [95% CI 0.84-0.94]; p < 2.4 × 10-5) and was nominally associated with the risk of inflammatory bowel disease (OR 0.85 [95% CI 0.74-0.98]; p < 0.03), Crohn disease (OR 0.81 [95% CI 0.70-0.94]; p < 0.005), psoriatic arthritis (OR 1.36 [95% CI 1.00-1.84]; p < 0.049), knee osteoarthritis (OR 1.17 [95% CI 1.01-1.36]; p < 0.04), and bipolar disorder (OR 1.21 [95% CI 1.05-1.40]; p < 0.007) and with an increase of 0.72 (95% CI 0.11-1.34; p < 0.02) mm Hg in systolic blood pressure, 0.45 (95% CI 0.06-0.84; p < 0.02) mm Hg in diastolic blood pressure, 0.01 ml/min/1.73 m2 (95% CI 0.003-0.02; p < 0.005) in estimated glomerular filtration rate from serum creatinine, 0.01 g/dl (95% CI 0.0004-0.02; p < 0.04) in serum albumin level, and 0.03 g/dl (95% CI 0.008-0.05; p < 0.009) in serum protein level. However, after adjustment for heterogeneity, neither GRS showed a significant effect of CRP level (at p < 0.0016) on any of these outcomes, including coronary artery disease, nor on the other 20 complex outcomes studied. Our study has two potential limitations: the limited variance explained by our genetic instruments modeling CRP levels in blood and the unobserved bias introduced by the use of summary statistics in our MR analyses.

CONCLUSIONS

Genetically elevated CRP levels showed a significant potentially protective causal relationship with risk of schizophrenia. We observed nominal evidence at an observed p < 0.05 using either GRSCRP or GRSGWAS-with persistence after correction for heterogeneity-for a causal relationship of elevated CRP levels with psoriatic osteoarthritis, rheumatoid arthritis, knee osteoarthritis, systolic blood pressure, diastolic blood pressure, serum albumin, and bipolar disorder. These associations remain yet to be confirmed. We cannot verify any causal effect of CRP level on any of the other common somatic and neuropsychiatric outcomes investigated in the present study. This implies that interventions that lower CRP level are unlikely to result in decreased risk for the majority of common complex outcomes.

Multibiomarker disease activity score and C-reactive protein in a cross-sectional observational study of patients with rheumatoid arthritis with and without concomitant fibromyalgia

OBJECTIVES

To examine the association between a multibiomarker disease activity (MBDA) score, CRP and clinical disease activity measures among RA patients with and without concomitant FM.

METHODS

In an observational cohort of patients with established RA, we performed a cross-sectional analysis comparing MBDA scores with CRP by rank correlation and cross-classification. MBDA scores, CRP and clinical measures of disease activity were compared between patients with RA alone and RA with concomitant FM (RA and FM) by univariate and multivariate analyses.

RESULTS

CRP was ⩽1.0 mg/dl for 184 of 198 patients (93%). MBDA scores correlated with CRP (r = 0.755, P < 0.001), but were often discordant, being moderate or high for 19%, 55% and 87% of patients with CRP ⩽0.1, 0.1 to ⩽0.3, or 0.3 to ⩽1.0 mg/dl, respectively. Among patients with CRP ⩽1.0 mg/dl, swollen joint count (SJC) increased linearly across levels of MBDA score, both with (P = 0.021) and without (P = 0.004) adjustment for CRP, whereas CRP was not associated with SJC. The 28-joint-DAS-CRP, other composite measures, and their non-joint-count component measures were significantly greater for patients with RA and FM (n = 25) versus RA alone (n = 173) (all P ⩽ 0.005). MBDA scores and CRP were similar between groups.

CONCLUSION

MBDA scores frequently indicated RA disease activity when CRP did not. Neither one was significantly greater among patients with RA and FM versus RA alone. Thus, MBDA score may be a useful objective measure for identifying RA patients with active inflammation when CRP is low (⩽1.0 mg/dl), including RA patients with concomitant FM.

The role of genetic variants in CRP in radiographic severity in African Americans with early and established rheumatoid arthritis

This study investigates the association of CRP (C-reactive protein) single-nucleotide polymorphisms (SNPs) with plasma CRP levels and radiographic severity in African Americans with early and established rheumatoid arthritis (RA). Using a cross-sectional case-only design, CRP SNPs were genotyped in two independent sets of African Americans with RA: Consortium for the Longitudinal Evaluation of African Americans with RA (CLEAR 1) and CLEAR 2. Radiographic data and CRP measurements were available for 294 individuals from CLEAR 1 (median (interquartile range (IQR) 25-75) disease duration of 1 (0.6-1.6) year) and in 407 persons from CLEAR 2 (median (IQR 25-75) disease duration of 8.9 (3.5-17.7) years). In CLEAR 1, in adjusted models, the minor allele of rs2808630 was associated with total radiographic score (incident rate ratio 0.37 (95% confidence interval (CI) 0.19-0.74), P-value=0.0051). In CLEAR 2, the minor allele of rs3093062 was associated with increased plasma CRP levels (P-value=0.002). For each rs3093062 minor allele, the plasma CRP increased by 1.51 (95% CI 1.15-1.95) mg dl(-1) when all the other covariates remained constant. These findings have important implications for assessment of the risk of joint damage in African Americans with RA.

Calprotectin as a biomarker for rheumatoid arthritis: a systematic review

OBJECTIVE

Calprotectin (myeloid-related protein 8/14), a heterodimeric complex of calcium-binding proteins, is expressed in granulocytes and monocytes. Calprotectin levels are high in synovial tissue, particularly in activated cells adjacent to the cartilage-pannus junction. This systematic review evaluates the use of calprotectin as an indicator of disease activity, therapeutic response, and prognosis in rheumatoid arthritis (RA).

METHODS

Medline, Scopus, and the Cochrane Library (1970-2013) were searched for studies containing original data from patients with RA in whom calprotectin levels were measured in plasma/serum and/or synovial fluid (SF). We included studies examining associations between calprotectin levels and clinical and laboratory assessments, disease progression, and therapeutic response. There were no restrictions for sample size, disease duration, or length of followup.

RESULTS

We evaluated 17 studies (1988-2013) with 1065 patients enrolled; 11 were cross-sectional and 8 had longitudinal designs with 2 studies reporting cross-sectional and longitudinal data. Systemic and SF levels of calprotectin were raised in RA. There was a wide range of levels and marked interstudy and intrastudy variability. Calprotectin levels were high in active disease and were particularly high in rheumatoid factor (RF)-positive patients. Levels fell with effective treatment. Longitudinal data showed that calprotectin was a significant and independent predictor of erosive progression and therapeutic responses, particularly in patients who received effective biological treatments.

CONCLUSION

SF calprotectin levels are high, suggesting there is substantial local production by inflamed synovium. Blood calprotectin levels, though highly variable, are elevated in active RA and fall with effective therapy. High baseline calprotectin levels predict future erosive damage.

Predicting therapeutic response in patients with heart failure: the story of C-reactive protein

Heart failure continues to be a major public health burden in the USA. With markedly high rates of morbidity and mortality upon diagnosis, effective treatment and prognosis are critical in the management of chronic heart failure. Growing evidence now supports the hypothesis that inflammation plays a key role in the progression and worsening of heart failure. Of the various inflammatory mediators identified, C-reactive protein, an acute phase inflammatory marker, has been associated with poor prognosis in patients with heart failure. Several interventional studies have been investigated to explore C-reactive protein modulation and potential treatment options and health outcomes; however, further studies are warranted before C-reactive protein-targeted therapy may be recommended in the management of heart failure.

CRP genotype and haplotype associations with serum C-reactive protein level and DAS28 in untreated early rheumatoid arthritis patients

INTRODUCTION

Single-nucleotide polymorphisms (SNPs) in the CRP gene are implicated in the regulation of the constitutional C-reactive protein (CRP) expression and its response to proinflammatory stimuli. Previous reports suggest that these effects may have an impact on clinical decision-making tools based on CRP, such as the Disease Activity Score in 28 joints (DAS28). We aimed to investigate the possible association between seven CRP SNPs, their haplotypes and the serum levels of CRP, as well as DAS28 scores, in two cohorts of untreated active early rheumatoid arthritis (RA) patients followed during their initial treatment.

METHODS

Overall, 315 patients with RA from two randomized controlled trials (the CIMESTRA and OPERA trials) who were naïve to disease-modifying antirheumatic drugs and steroids with disease durations less than 6 months were included. Seven CRP SNPs were investigated: rs11265257, rs1130864, rs1205, rs1800947, rs2808632, rs3093077 and rs876538. The genotype and haplotype associations with CRP and DAS28 levels were evaluated using linear regression analysis adjusted for age, sex and treatment.

RESULTS

The minor allele of rs1205 C > T was associated with decreased CRP levels at baseline (P = 0.03), with the TT genotype having a 50% reduction in CRP from 16.7 to 8.4 mg/L (P = 0.005) compared to homozygosity of the major allele, but no association was observed at year 1 (P = 0.38). The common H2 haplotype, characterized by the T allele of rs1205, was associated with a 26% reduction in CRP at baseline (P = 0.043), although no effect was observed at year 1 (P = 0.466). No other SNP or haplotype was associated with CRP at baseline or at year 1 (P ≥ 0.09). We observed no associations between SNPs or haplotypes and DAS28 scores at baseline or at year 1 (P ≥ 0.10).

CONCLUSION

CRP genotype and haplotype were only marginally associated with serum CRP levels and had no association with the DAS28 score. This study shows that DAS28, the core parameter for inflammatory activity in RA, can be used for clinical decision-making without adjustment for CRP gene variants.

TRIAL REGISTRATION

The OPERA study is registered at Clinicaltrials.gov (NCT00660647). The CIMESTRA study is not listed in a clinical trials registry, because patients were included between October 1999 and October 2002.

Serum C-reactive protein level but not its gene polymorphism is associated with Takayasu arteritis

Takayasu arteritis (TA) patients with active disease often have elevated serum C-reactive protein (CRP) levels, which usually decline with the disease remission. The serum CRP concentration has been showed to be related to CRP gene polymorphisms in previous studies. The present study aims to investigate the associations of serum level of CRP and CRP polymorphisms with TA. A total of 178 unrelated Chinese Han TA patients and 229 unrelated Chinese Han individuals without documented disease were enrolled in our studies. After a systemic search in the HapMap database, four single-nucleotide polymorphisms (SNPs) were selected, namely, rs1800947, rs3093077, rs1205, and rs2808630. The ligase detection reaction (LDR) was used in genotyping. CRP concentrations were determined using turbidimetric immunoassay. Genotype frequencies and allele frequencies of CRP variations were similar between TA patients and controls. CRP haplotype frequencies in patients were not significantly different from those of controls. No significant association between serum CRP concentrations and genotypes was found. Moreover, no association was found in CRP concentration between patients with types I, II, and III TA or between patients with or without pulmonary involvement. By contrast, serum CRP concentration was directly correlated with disease severity. In conclusion, CRP polymorphisms were not associated with TA susceptibility or serum CRP levels in the Chinese Han population. However, higher CRP level was correlated with a more serious disease status, which implies that CRP possibly contributes to the progression of TA.

C-reactive protein in Crohn's disease: how informative is it?

C-reactive protein (CRP) is an important acute-phase marker, produced mainly in the liver. Its production by mesenteric adipocytes has been recently stressed in Crohn's disease (CD). There are many factors affecting CRP levels, both environmental and genetics. The short-life of this biomarker makes it of pertinent use in the assessment of inflammation. There are inconsistent results concerning the association of clinical activity indices, mucosal healing, histological activity and CRP. This review summarizes the role of CRP in CD, namely its importance in the differential diagnosis of CD; its relationship with clinical activity indices, other markers of inflammation and endoscopic and radiological cross sectional imaging; prediction of response to anti-TNF treatment and prediction of outcome.

PBMC and exosome-derived Hotair is a critical regulator and potent marker for rheumatoid arthritis

Despite growing importance of long non-coding RNAs (lncRNAs) in normal physiological and disease conditions, our knowledge of RA-related lncRNAs remains limited. Therefore, we aimed to identify lncRNA signatures that have prognostic values in RA. There was a notably high expression level of Hotair in blood mononuclear cells and serum exosome of rheumatoid arthritis (RA) patients, leading the migration of active macrophage. In contrast, markedly lower level of Hotair was detected in differentiated osteoclasts and rheumatoid synoviocytes and enforced expression of Hotair led to significantly decreased levels of MMP-2 and MMP-13. This exploratory study provides novel empirical evidence that Hotair could be one of potential biomarkers for diagnosing RA.

Calprotectin in rheumatoid arthritis : association with disease activity in a cross-sectional and a longitudinal cohort

BACKGROUND

Calprotectin is potentially a more sensitive biomarker of disease activity in rheumatoid arthritis (RA) than conventional acute-phase proteins such as the erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) because it directly reflects inflammation in the synovium and synovial fluid rather than systemic inflammatory activity.

OBJECTIVE

The aim of this study was to evaluate relationships between serum calprotectin levels, disease activity, and response to treatment. Calprotectin was also investigated as a predictive marker of clinical response.

METHODS

This observational study included selected cohorts of patients with RA treated at La Paz University Hospital, Madrid, Spain. Associations between serum calprotectin levels and clinical and laboratory parameters were analyzed in a cross-sectional cohort of 60 patients with varying disease activity, and changes in calprotectin levels in response to treatment with infliximab were analyzed at baseline and after 3 and 6 months of treatment in a longitudinal cohort of 20 patients with very active disease.

RESULTS

In the cross-sectional cohort, calprotectin levels correlated with rheumatoid factor levels (r = 0.25; p < 0.05) but not with titers of antibodies to cyclic citrullinated peptide. Significant correlations were also observed between calprotectin levels and the 28 swollen joint count (28-SJC), Disease Activity Score based on a 28-joint count (DAS28), Simplified Disease Activity Index (SDAI), ESR, and CRP levels. In the longitudinal cohort, calprotectin levels at baseline were not predictive of response to treatment but significantly decreased during treatment in responders (p < 0.0001).

CONCLUSION

Calprotectin levels strongly correlate with clinical and laboratory assessments of joint inflammation and also decrease in response to treatment, indicating that calprotectin is a promising marker for assessment and monitoring of disease activity in patients with RA. Investigations are required to further evaluate its diagnostic, prognostic, and therapeutic potential.

Development of a multi-biomarker disease activity test for rheumatoid arthritis

Background

Disease activity measurement is a key component of rheumatoid arthritis (RA) management. Biomarkers that capture the complex and heterogeneous biology of RA have the potential to complement clinical disease activity assessment.

Objectives

To develop a multi-biomarker disease activity (MBDA) test for rheumatoid arthritis.

Methods

Candidate serum protein biomarkers were selected from extensive literature screens, bioinformatics databases, mRNA expression and protein microarray data. Quantitative assays were identified and optimized for measuring candidate biomarkers in RA patient sera. Biomarkers with qualifying assays were prioritized in a series of studies based on their correlations to RA clinical disease activity (e.g. the Disease Activity Score 28-C-Reactive Protein [DAS28-CRP], a validated metric commonly used in clinical trials) and their contributions to multivariate models. Prioritized biomarkers were used to train an algorithm to measure disease activity, assessed by correlation to DAS and area under the receiver operating characteristic curve for classification of low vs. moderate/high disease activity. The effect of comorbidities on the MBDA score was evaluated using linear models with adjustment for multiple hypothesis testing.

Results

130 candidate biomarkers were tested in feasibility studies and 25 were selected for algorithm training. Multi-biomarker statistical models outperformed individual biomarkers at estimating disease activity. Biomarker-based scores were significantly correlated with DAS28-CRP and could discriminate patients with low vs. moderate/high clinical disease activity. Such scores were also able to track changes in DAS28-CRP and were significantly associated with both joint inflammation measured by ultrasound and damage progression measured by radiography. The final MBDA algorithm uses 12 biomarkers to generate an MBDA score between 1 and 100. No significant effects on the MBDA score were found for common comorbidities.

Conclusion

We followed a stepwise approach to develop a quantitative serum-based measure of RA disease activity, based on 12-biomarkers, which was consistently associated with clinical disease activity levels.

Validation of a novel multibiomarker test to assess rheumatoid arthritis disease activity

Objective Quantitative assessment of disease activity in rheumatoid arthritis (RA) is important for patient management, and additional objective information may aid rheumatologists in clinical decision making. We validated a recently developed multibiomarker disease activity (MBDA) test relative to clinical disease activity in diverse RA cohorts.

Methods Serum samples were obtained from the Index for Rheumatoid Arthritis Measurement, Brigham and Women's Hospital Rheumatoid Arthritis Sequential Study, and Leiden Early Arthritis Clinic cohorts. Levels of 12 biomarkers were measured and combined according to a prespecified algorithm to generate the composite MBDA score. The relationship of the MBDA score to clinical disease activity was characterized separately in seropositive and seronegative patients using Pearson's correlations and the area under the receiver operating characteristic curve (AUROC) to discriminate between patients with low and moderate/high disease activity. Associations between changes in MBDA score and clinical responses 6–12 weeks after initiation of anti–tumor necrosis factor or methotrexate treatment were evaluated by the AUROC.

Results The MBDA score was significantly associated with the Disease Activity Score in 28 joints using the C-reactive protein level (DAS28-CRP) in both seropositive (AUROC 0.77, P < 0.001) and seronegative (AUROC 0.70, P < 0.001) patients. In subgroups based on age, sex, body mass index, and treatment, the MBDA score was associated with the DAS28-CRP (P < 0.05) in all seropositive and most seronegative subgroups. Changes in the MBDA score at 6–12 weeks could discriminate both American College of Rheumatology criteria for 50% improvement responses (P = 0.03) and DAS28-CRP improvement (P = 0.002). Changes in the MBDA score at 2 weeks were also associated with subsequent DAS28-CRP response (P = 0.02).

Conclusion Our findings establish the criterion and discriminant validity of a novel multibiomarker test as an objective measure of RA disease activity to aid in the management of RA in patients with this condition.

C-reactive protein and preterm delivery: clues from placental findings and maternal weight

To study the association between maternal C-reactive protein (CRP) and preterm delivery (PTD) pathways, CRP was measured in maternal plasma collected at mid-pregnancy (n = 1310). PTD was subdivided into spontaneous (sPTD) or medically indicated (MI-PTD). Histologic chorioamnionitis (HCA) was determined by placental histopathology (n = 1076). Adjusted CRP levels were elevated for sPTD (5.5 µg/mL) versus term deliveries (4.8 µg/mL) and higher in sPTD with HCA (6.3 µg/mL). After removing HCA, an interaction between body mass index (BMI) and sPTD in relation to CRP was noted. In BMI-stratified models, an association between CRP and sPTD among women with prepregnancy BMI >25 (8.9 µg/mL for sPTD; 7.2 µg/mL for term) was absent among women with lower BMI. We propose that this remaining association in overweight/obese women suggests that CRP may mark an obesity/inflammation PTD pathway that is distinct from the pathway indicated by HCA.

Correlation of C-reactive protein haplotypes with serum C-reactive protein level and response to anti-tumor necrosis factor therapy in UK rheumatoid arthritis patients: results from the Biologics in Rheumatoid Arthritis Genetics and Genomics Study Syndicate cohort

INTRODUCTION

In many European countries, restrictions exist around the prescription of anti-tumor necrosis factor (anti-TNF) treatments for rheumatoid arthritis (RA). Eligibility and response to treatment is assessed by using the disease activity score 28 (DAS28) algorithm, which incorporates one of two inflammatory markers, erythrocyte sedimentation rate (ESR) or C-reactive protein (CRP). Although DAS28-CRP provides a more reliable measure of disease activity, functional variants exist within the CRP gene that affect basal CRP production.

METHODS

DNA samples from the Biologics in Rheumatoid Arthritis Genetics and Genomics Study Syndicate (BRAGGSS) were genotyped for rs1205, rs1800947, and rs3091244 by using either TaqMan or the Sequenom MassARRAY iPLEX system.

RESULTS

Baseline CRP measurements were available for 599 samples with 442 also having data 6 months after treatment with an anti-TNF. For these 442 samples, the study had > 80% power to detect a clinically meaningful difference of 0.6 DAS28 Units for an allele frequency of 5%. Estimated haplotype frequencies corresponded with previous frequencies reported in the literature. Overall, no significant association was observed between any of the markers investigated and baseline CRP levels. Further, CRP haplotypes did not correlate with baseline CRP (P = 0.593), baseline DAS28-CRP (P = 0.540), or change in DAS28-CRP after treatment with an anti-TNF over a 6-month period (P = 0.302).

CONCLUSIONS

Although CRP genotype may influence baseline CRP levels, in patients with very active disease, no such association was found. This suggests that genetic variation at the CRP locus does not influence DAS28-CRP, which may continue to be used in determining eligibility for and response to anti-TNF treatment, without adjusting for CRP genotype.

Influence of MIF, CD40, and CD226 polymorphisms on risk of rheumatoid arthritis

Macrophage migration inhibitory factor (MIF) is a key pro-inflammatory mediator. It plays an important role part in the pathogenesis of several inflammatory and immune diseases. A functional single nucleotide polymorphism (SNP) of MIF -173 G/C is known to influence MIF promoter activity in T lymphoblast cell lines and is associated with a higher serum MIF level. The CD40 is also crucial for some relevant functions of the immune system and may be related to rheumatoid arthritis (RA). And CD226 is an important cell-surface receptor molecule involved in the adhesion and activation of T-cell. We hypothesized that these polymorphisms may contribute to RA susceptibility. We studied MIF -173 G/C, CD40, and CD226 gene polymorphisms in 214 patients with RA and 478 controls in a Chinese population. Genotyping was done by using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). When the MIF -173 GG homozygote genotype was used as the reference group, the CC genotype was associated with a significantly increased risk for RA. In the recessive model, when the MIF -173 GG/GC genotypes were used as the reference group, the CC homozygote genotype was associated with a significant 1.56-fold increased susceptibility to RA. None of the CD40 rs1883832 C/T and CD226 rs763361 C/T polymorphisms achieved a significant difference in genotype distributions between cases and controls. In the stratification analyzes, a significantly increased risk for RA associated with the MIF -173 CC genotype was evident among CRP-negative patients compared with the MIF -173 GG/GC genotype. For the CD40 rs1883832 C/T variant, the risk effects of CD40 rs1883832 TT versus CD40 rs1883832 CC/CT were significant in men. These findings suggested that the functional SNP MIF -173 G/C variant allele was associated with the development of RA. However, CD40 and CD226 gene polymorphisms may not be associated with RA susceptibility. Due to the limitation of sample size, this study should be considered preliminary.

Poor trabecular microarchitecture at the distal radius in older men with increased concentration of high-sensitivity C-reactive protein--the STRAMBO study

Low-grade inflammation, assessed by serum high-sensitivity C-reactive protein (hsCRP) concentration, is associated with higher fracture risk irrespective of areal bone mineral density (aBMD). We assessed the association of hsCRP with bone microarchitecture (measured by high-resolution pQCT) at the distal radius and tibia in 1,149 men, aged 19-87 years. hsCRP concentration increased with age until the age of 72, then remained stable. aBMD was not correlated with hsCRP level. After adjustment for confounders, bone microarchitecture was not associated with hsCRP level in men aged <72. After the age of 72, hsCRP >5 mg/L was associated with lower trabecular density, lower trabecular number, higher trabecular spacing, and more heterogeneous trabecular distribution (p < 0.05-0.005) at the distal radius versus hsCRP ≤ 5 mg/L. Similar differences were found for the fourth hsCRP quartile (>3.69 mg/L) versus the three lower quartiles combined. Cortical parameters of distal radius and microarchitectural parameters of distal tibia did not vary according to hsCRP concentration in men aged ≥ 72. Fracture prevalence increased with increasing hsCRP level. After adjustment for confounders (including aBMD), odds for fracture were higher in men with hsCRP >5 mg/L compared to hsCRP <1 mg/L (OR = 2.22, 95 % CI 1.29-3.82) and did not change after additional adjustment for microarchitectural parameters. The association between hsCRP level and bone microarchitecture was observed only for trabecular parameters at the radius in men aged ≥72. Impaired bone microarchitecture does not seem to explain the association between elevated CRP level and higher risk of fracture.

Value of acute-phase reactants in monitoring disease activity and treatment response in idiopathic retroperitoneal fibrosis

BACKGROUND

Prospective evaluation of the value of erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) levels in monitoring disease activity and treatment response in patients with idiopathic retroperitoneal fibrosis (RPF).

METHODS

This study included 57 patients with idiopathic RPF receiving tamoxifen monotherapy with at least 8 months follow-up. Clinical, laboratory and radiological investigation was performed at presentation and at repeated follow-up. Remission was defined as significant clinical improvement within 6 weeks of treatment together with stable or decreasing mass size on follow-up computed tomography (CT) scanning at 4 months and definitive decrease in mass size on follow-up CT scanning at 8 months.

RESULTS

ESR and CRP levels at presentation and their respective decreases over time correlated strongly with each other (P<0.001). Baseline ESR and CRP levels correlated with visual analogue scale (VAS) score for pain (ESR, P<0.01; CRP, P<0.001); baseline ESR levels also correlated with VAS score for discomfort (P<0.001). Short-term decreases in ESR or CRP levels at 6 weeks follow-up did not correlate with subsequent mass regression but decrease in ESR at 4 months and decrease in CRP at 4 and 8 months follow-up correlated with mass regression. Kaplan-Meier analysis showed no difference in remission rate between patients with normal or elevated baseline ESR or CRP (log-rank P=0.22/P=0.88) or between patients with or without (near-)normalization of ESR or CRP in first 6 weeks of treatment (log-rank P=0.12/P=0.32).

CONCLUSIONS

Patients with idiopathic RPF who have elevated acute-phase reactant levels are more symptomatic. Neither acute-phase reactant levels or their initial changes can be taken as a major predictor for treatment success.

Association of polymorphisms in pre-miRNA with inflammatory biomarkers in rheumatoid arthritis in the Chinese Han population

The aim of this study was to detect the association between 2 single nucleotide polymorphisms (SNPs), rs2910164 G>C and rs3746444 T>C, in pre-miRNA (hsa-mir-146a and hsa-mir-499) and the chronic inflammation in the Chinese Han population with rheumatoid arthritis (RA). Two hundred sixty-two Han Chinese patients with RA were recruited in this study. The SNPs were genotyped by polymerase chain reaction restriction fragment length polymorphism. C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and the plasma concentrations of interleukin (IL)-6, tumor necrosis factor α (TNF-α), and transforming growth factor β1 (TGF-β1) were measured. There was a significant difference in the levels of CRP and ESR among different genotypes in rs3746444 (p = 0.031 and p = 0.047, respectively). The heterozygote CT had significantly higher levels of CRP and ESR compared with homozygotes CC and TT. No significant association was observed between the SNP rs2910164 and the levels of CRP, ESR, IL-6, TNF-α, and TGF-β1 (all p > 0.05). The results of this study provided the first evidence that the SNP rs3746444 in pre-miR-499 could affect the inflammatory reaction in patients with RA. The findings were significant and might contribute to the clinical assessment of inflammatory activity, which in turn may influence therapeutic decision making.