Decreases in serum levels of S100A8/9 (calprotectin) correlate with improvements in total swollen joint count in patients with recent-onset rheumatoid arthritis

The Role of Alarmins in the Pathogenesis of Rheumatoid Arthritis, Osteoarthritis, and Psoriasis

Alarmins are immune-activating factors released after cellular injury or death. By secreting alarmins, cells can interact with immune cells and induce a variety of inflammatory responses. The broad family of alarmins involves several members, such as high-mobility group box 1, S100 proteins, interleukin-33, and heat shock proteins, among others. Studies have found that the concentrations and expression profiles of alarmins are altered in immune-mediated diseases. Furthermore, they are involved in the pathogenesis of inflammatory conditions. The aim of this narrative review is to present the current evidence on the role of alarmins in rheumatoid arthritis, osteoarthritis, and psoriasis. We discuss their potential involvement in mechanisms underlying the progression of these diseases and whether they could become therapeutic targets. Moreover, we summarize the impact of pharmacological agents used in the treatment of these diseases on the expression of alarmins.

A bioavailable form of curcumin suppresses cationic host defence peptides cathelicidin and calprotectin in a murine model of collagen-induced arthritis

Curcumin, a component of the South-Asian spice turmeric, elicits anti-inflammatory functions. We have previously demonstrated that a highly bioavailable formulation of cucurmin, Cureit/Acumin™ (CUR), can suppress disease onset and severity, in a collagen-induced arthritis (CIA) mouse model. In a previous study, we have also shown that the abundance of antimicrobial host defence peptides, specifically cathelicidin (CRAMP) and calprotectin (S100A8 and S100A9), is significantly increased in the joint tissues of CIA mice. Elevated levels of cathelicidin and calprotectin have been associated with the pathogenesis of rheumatoid arthritis. Therefore, in this study, we examined the effect CUR administration on the abundance of cathelicidin and calprotectin in the joints, in a CIA mouse model. Here, we demonstrate that daily oral administration of CUR significantly reduces the elevated levels of CRAMP and calprotectin to baseline in the joints of CIA mice. We also show a linear correlation between the abundance of these peptides in the joints with serum inflammatory cytokines TNFα, IFNγ, and MCP-1. Overall, our results suggest that oral administration of a bioavailable CUR can suppress cathelicidin and calprotectin in the joints and regulate both local (joints) and systemic (serum) inflammation, in inflammatory arthritis.

Assessment of Intestinal Permeability and Inflammation Bio-Markers in Patients with Rheumatoid Arthritis

Increased intestinal permeability and inflammation, both fueled by dysbiosis, appear to contribute to rheumatoid arthritis (RA) pathogenesis. This single-center pilot study aimed to investigate zonulin, a marker of intestinal permeability, and calprotectin, a marker of intestinal inflammation, measured in serum and fecal samples of RA patients using commercially available kits. We also analyzed plasma lipopolysaccharide (LPS) levels, a marker of intestinal permeability and inflammation. Furthermore, univariate, and multivariate regression analyses were carried out to determine whether or not there were associations of zonulin and calprotectin with LPS, BMI, gender, age, RA-specific parameters, fiber intake, and short-chain fatty acids in the gut. Serum zonulin levels were more likely to be abnormal with a longer disease duration and fecal zonulin levels were inversely associated with age. A strong association between fecal and serum calprotectin and between fecal calprotectin and LPS were found in males, but not in females, independent of other biomarkers, suggesting that fecal calprotectin may be a more specific biomarker than serum calprotectin is of intestinal inflammation in RA. Since this was a proof-of-principle study without a healthy control group, further research is needed to validate fecal and serum zonulin as valid biomarkers of RA in comparison with other promising biomarkers.

Pre-treatment calprotectin (MRP8/14) provides no added value to testing CRP alone in terms of predicting response to TNF inhibitors in rheumatoid arthritis in a post hoc analysis

OBJECTIVES

The inflammatory protein calprotectin (MRP8/14) has been identified as a promising biomarker of treatment response in rheumatoid arthritis (RA). Our aim was to test MRP8/14 as a biomarker of response to tumour necrosis factor (TNF)-inhibitors in the largest RA cohort to date and to compare with C-reactive protein (CRP).

METHODS

Serum MRP8/14 was measured in 470 patients with RA about to commence treatment with adalimumab (n=196) or etanercept (n=274). Additionally, MRP8/14 was measured in the 3-month sera of 179 adalimumab-treated patients. Response was determined using European League against Rheumatism (EULAR) response criteria calculated using the traditional 4-component (4C) DAS28-CRP and alternate validated versions using 3-component (3C) and 2-component (2C), clinical disease activity index (CDAI) improvement criteria and change in individual outcome measures. Logistic/linear regression models were fitted for response outcome.

RESULTS

In the 3C and 2C models, patients with RA were 1.92 (CI: 1.04 to 3.54) and 2.03 (CI: 1.09 to 3.78) times more likely to be classified as EULAR responders if they had high (75th quartile) pre-treatment levels of MRP8/14 compared with low (25th quartile). No significant associations were observed for the 4C model. When only using CRP as a predictor, in the 3C and 2C analyses, patients above the 75th quartile were 3.79 (CI: 1.81 to 7.93) and 3.58 (CI: 1.74 to 7.35) times more likely to be EULAR responders and addition of MRP8/14 did not significantly improve model fit (p values=0.62 and 0.80, respectively). No significant associations were observed in the 4C analysis. Exclusion of CRP from the outcome measure (CDAI) did not result in any significant associations with MRP8/14 (OR 1.00 (CI: 0.99 to 1.01), suggesting that the associations were due to the correlation with CRP and that there is no additional utility of MRP8/14 beyond use of CRP in patients with RA starting TNFi therapy.

CONCLUSION

Beyond correlation with CRP, we found no evidence to suggest that MRP8/14 explains additional variability in response to TNFi in patients with RA over and above CRP alone.

Dipeptidyl peptidase 4 as a potential serum biomarker for disease activity and treatment response in rheumatoid arthritis

BACKGROUND

The treatment of rheumatoid arthritis (RA) related to the disease activity. However, the lack of highly sensitive and simplified markers limits the evaluation of disease activity. We sought to explore potential biomarkers associated with disease activity and treatment response in RA.

METHODS

Liquid chromatography-tandem mass spectrometry (LC-MS/MS) proteomic analysis was performed to determine the differentially expressed proteins (DEPs) in serum collected from RA patients with moderate or high disease activity (determined by DAS28) before and after 24 weeks of treatment. Bioinformatic analysis were performed for DEPs and hub proteins. In the validation cohort, 15 RA patients were enrolled. Key proteins were validated by enzyme-linked immunosorbent assay (Elisa), correlation analysis and ROC curve.

RESULTS

We identified 77 DEPs. The DEPs enriched in humoral immune response, blood microparticle, and serine-type peptidase activity. KEGG enrichment analysis displayed that the DEPs were significantly enriched in cholesterol metabolism and complement and coagulation cascades. Activated CD4 + T cell, T follicular helper cell, natural killer cell, and plasmacytoid dendritic cell significantly increased after treatment. Fifteen hub proteins were screened out. Among them, dipeptidyl peptidase 4 (DPP4) was the most significant protein associated with clinical indicators and immune cells. Serum concentration of DPP4 was testified to significantly increase after treatment and inversely correlate with disease activity indicators (ESR, CRP, DAS28-ESR, DAS28-CRP, CDAI, SDAI). Significant reduction was found in the serum CXC chemokine ligand10 (CXC10) and CXC chemokine receptor 3 (CXCR3) after treatment.

CONCLUSIONS

Overall, our results suggest that serum DPP4 might be a potential biomarker for disease activity assessment and treatment response of RA.

Circulating Calprotectin (cCLP) in autoimmune diseases

BACKGROUND AND AIM

Calprotectin (CLP) is a heterodimeric complex formed by two S100 proteins (S100A8/A9), which plays a pivotal role in innate immunity. Due to its intrinsic cytotoxic and proinflammatory properties, CLP controls cell differentiation, proliferation and NETosis and has been associated with a wide range of rheumatic diseases. Our review summarizes the widespread interest in circulating CLP (cCLP) as a biomarker of neutrophil-related inflammation, in autoimmune rheumatic disease (ARD) and non-ARD.

METHODS

A thorough literature review was performed using PubMed and EMBASE databases searching for circulating calprotectin and synonyms S100A8/A9, myeloid-related protein 8/14 (MRP8/MRP14), calgranulin A/B and L1 protein in addition to specific ARDs and autoimmune non-rheumatic diseases. We selected only English-language articles and excluded abstracts without the main text.

RESULTS

High cCLP serum levels are associated with worse structural outcomes in rheumatoid arthritis and to a lesser extent, in spondyloarthritis. In addition, cCLP can predict disease relapse in some autoimmune diseases including systemic lupus erythematosus (SLE), anti-neutrophil cytoplasmic antibodies-associated vasculitis (AAV) and some severe manifestations of connective tissue diseases, such as glomerulonephritis in SLE, AAV, juvenile idiopathic arthritis, adult-onset Still's disease and lung fibrosis in systemic sclerosis. Therefore, cCLP levels enable the identification of patients who need an accurate and tight follow-up. The clinical usefulness of cCLP as an inflammatory marker has been suggested for inflammatory/autoimmune non-rheumatic diseases, and especially for the monitoring of the inflammatory bowel diseases patients. Currently, there are only a few studies that evaluated the cCLP efficacy as a clinical biomarker in inflammatory/autoimmune non-rheumatic diseases with controversial results. Future studies are warranted to better clarify the role of cCLP in relation to the disease severity in myasthenia gravis, multiple sclerosis, chronic inflammatory demyelinating polyneuropathy, Graves' orbitopathy, autoimmune bullous diseases and uveitis.

CONCLUSION

Our literature review supports a relevant role of cCLP as potential prognostic biomarker mirroring local or systemic inflammation, especially in chronic inflammatory rheumatic diseases.

Linkage of calprotectin with inflammation, activity and treatment response of rheumatoid arthritis: a meta-analysis

Aim: This meta-analysis aimed to investigate the clinical value of calprotectin in rheumatoid arthritis (RA) patients. Methods: The data regarding blood calprotectin levels in RA patients were retrieved from PubMed, Embase, Web of Science and Cochrane databases. Results: Thirty-one eligible articles were included. Calprotectin was increased in RA patients compared with healthy controls (mean difference [MD] = 1.48, 95% CI: 1.16-1.79). Calprotectin was positively associated with C-reactive protein (correlation coefficient [CC] = 0.58, 95% CI: 0.53-0.63) and disease activity score (CC = 0.48, 95% CI: 0.38-0.58) in RA patients. Interestingly, calprotectin showed an increased trend in RA responders compared with nonresponders, but without statistical significance (MD = 0.38, 95% CI: -0.09-0.85). Conclusion: Blood calprotectin relates to disease risk, inflammation and activity in RA patients.

From bench to bedside: Calprotectin (S100A8/S100A9) as a biomarker in rheumatoid arthritis

S100A9/S100A8 (calprotectin), a member of the S100 protein family, has been shown to play a pivotal role in innate immunity activation. Calprotectin plays a critical role in the pathogenesis of rheumatoid arthritis (RA), as it triggers chemotaxis, phagocyte migration and modulation of neutrophils and macrophages. Higher calprotectin levels have been found in synovial fluid, plasma, and serum from RA patients. Recent studies have demonstrated better correlations between serum or plasma calprotectin and composite inflammatory disease activity indexes than c-reactive protein (CRP) or the erythrocyte sedimentation rate (ESR). Calprotectin serum levels decreased after treatment, independently of the DMARD type or strategy. Calprotectin has shown the strongest correlations with other sensitive techniques to detect inflammation, such as ultrasound. Calprotectin independently predicts radiographic progression. However, its value as a biomarker of treatment response and flare after tapering is unclear. This update reviews the current understanding of calprotectin in RA and discusses possible applications as a biomarker in clinical practice.

Liver-Derived S100A6 Propels β-Cell Dysfunction in NAFLD

Nonalcoholic fatty liver disease (NAFLD) is an independent predictor of systemic insulin resistance and type 2 diabetes mellitus (T2DM). However, converse correlates between excess liver fat content and β-cell function remain equivocal. Specifically, how the accumulation of liver fat consequent to the enhanced de novo lipogenesis (DNL) leads to pancreatic β-cell failure and eventually to T2DM is elusive. Here, we have identified that low-molecular-weight calcium-binding protein S100A6, or calcyclin, inhibits glucose-stimulated insulin secretion (GSIS) from β cells through activation of the receptor for the advanced glycation end products and diminution of mitochondrial respiration. Serum S100A6 level is elevated both in human patients with NAFLD and in a high-fat diet-induced mouse model of NAFLD. Although serum S100A6 levels are negatively associated with β-cell insulin secretory capacity in human patients, depletion of hepatic S100A6 improves GSIS and glycemia in mice, suggesting that S100A6 contributes to the pathophysiology of diabetes in NAFLD. Moreover, transcriptional induction of hepatic S100A6 is driven by the potent regulator of DNL, carbohydrate response element-binding protein (ChREBP), and ectopic expression of ChREBP in the liver suppresses GSIS in a S100A6-sensitive manner. Together, these data suggest elevated serum levels of S100A6 may serve as a biomarker in identifying patients with NAFLD with a heightened risk of developing β-cell dysfunction. Overall, our data implicate S100A6 as, to our knowledge, a hitherto unknown hepatokine to be activated by ChREBP and that participates in the hepato-pancreatic communication to impair insulin secretion and drive the development of T2DM in NAFLD.

Evaluation of Serum Calprotectin Levels in Patients with Inflammatory Bowel Disease

BACKGROUND

Fecal calprotectin has been proposed as a useful biomarker of disease activity in inflammatory bowel disease (IBD). However, the role of calprotectin in systemic circulation is not well established. Thus, this study aimed to quantify serum calprotectin levels to identify a potential inflammatory marker for IBD.

METHODS

Ninety-eight patients with ulcerative colitis (UC) and 105 patients with Crohn's disease (CD) were prospectively enrolled and clinically scored. Ninety-two healthy, age-matched subjects served as controls. Blood samples from UC and CD patients and controls were analyzed for serum calprotectin levels and routine laboratory parameters. Disease activity was assessed by partial Mayo score and Harvey-Bradshaw index for UC and CD, respectively.

RESULTS

Serum calprotectin levels were higher in CD and UC patients than in controls and were higher during active disease than during inactive disease in CD but not in UC. In UC, serum calprotectin levels were correlated with C-reactive protein (CRP) but not with other laboratory parameters or disease activity. In CD, serum calprotectin levels were positively correlated with disease activity, serum CRP, and platelet count. In UC and CD, serum calprotectin and CRP levels increased during the acute phase and decreased towards remission.

CONCLUSIONS

Serum calprotectin is an inflammatory marker in IBD but might be more effective in evaluating patients with CD than those with UC. Further studies are needed to confirm these findings and to better determine the specific uses of serum calprotectin in routine practice.

Evaluation of fecal calprotectin as a marker of gastrointestinal inflammation in rosacea: A case-control study

A higher incidence of gastrointestinal diseases has been well established in patients with rosacea. However, no screening tool has been introduced for gastrointestinal disease development in rosacea. Fecal calprotectin (FC) is a calcium-binding protein, mainly derived from polymorpho-nuclear cells, such as neutrophils. It has been established as a marker of gastrointestinal inflammation. The aim of the present study was to evaluate FC levels in patients with rosacea without any gastrointestinal diseases. A prospective, case-control study was planned to investigate the relationship between rosacea and gastrointestinal involvement by evaluating FC levels and the Gastrointestinal Symptom Rating Scale (GSRS). A total of 47 patients with rosacea and 39 healthy control subjects were included in the study. The FC levels were statistically significantly higher in rosacea group than in the control group (65.96 ± 58.86 ng/mL vs 31.99 ± 20.12 ng/mL, P = .026, respectively). A statistically significant difference was also observed in GSRS values between the patient and the control groups (30.26 ± 12.48 vs 22.62 ± 7.64, P = .001, respectively). A positive correlation was noted between FC levels and the values of GSRS in the study group (r: 0.354; P = .001) and in the rosacea group (r = 0.392, P = .006). The measurement of FC may be useful in the early detection of gastrointestinal system diseases that may accompany rosacea and may provide a pathway to develop treatment strategies targeting both skin and intestinal mucosa.

Blood and synovial fluid calprotectin as biomarkers to diagnose chronic hip and knee periprosthetic joint infections

AIMS

Calprotectin (CLP) is produced in neutrophils and monocytes and released into body fluids as a result of inflammation or infection. The aim of this study was to evaluate the utility of blood and synovial CLP in the diagnosis of chronic periprosthetic joint infection (PJI).

METHODS

Blood and synovial fluid samples were collected prospectively from 195 patients undergoing primary or revision hip and knee arthroplasty. Patients were divided into five groups: 1) primary total hip and knee arthroplasty performed due to idiopathic osteoarthritis (OA; n = 60); 2) revision hip and knee arthroplasty performed due to aseptic failure of the implant (AR-TJR; n = 40); 3) patients with a confirmed diagnosis of chronic PJI awaiting surgery (n = 45); 4) patients who have finished the first stage of the PJI treatment with the use of cemented spacer and were qualified for replantation procedure (SR-TJR; n = 25), and 5) patients with rheumatoid arthritis undergoing primary total hip and knee arthroplasty (RA; n = 25). CLP concentrations were measured quantitatively in the blood and synovial fluid using an immunoturbidimetric assay. Additionally, blood and synovial CRP, blood interleukin-6 (IL-6), and ESR were measured, and a leucocyte esterase (LE) strip test was performed.

RESULTS

Patients with PJI had higher CLP concentrations than those undergoing aseptic revision in blood (median PJI 2.14 mg/l (interquartile range (IQR) 1.37 to 3.56) vs AR-TJR 0.66 mg/l (IQR 0.3 to 0.83); p < 0.001) and synovial fluid samples (median PJI 20.46 mg/l (IQR 14.3 to 22.36) vs AR-TJR 0.7 mg/l (IQR 0.41 to 0.95); p < 0.001). With a cut-off value of 1.0 mg/l, blood CLP showed a sensitivity, specificity, positive predictive value, and negative predictive value of 93.3%, 87.5%, 89.4%, and 92.1%, respectively. For synovial fluid with a cut-off value of 1.5 mg/l, these were 95.6%, 95%, 95.5%, and 95%, respectively.

CONCLUSION

This small study suggests that synovial and blood CLP are useful markers in chronic PJI diagnosis with similar or higher sensitivity and specificity than routinely used markers such as CRP, ESR, IL-6, and LE. CLP was not useful to differentiate patients with PJI from those with rheumatoid arthritis. Cite this article: Bone Joint J 2021;103-B(1):46-55.

Pre-analytical and analytical confounders of serum calprotectin as a biomarker in rheumatoid arthritis

Background There is a need for additional biomarkers to assist in the diagnosis and prognosis of rheumatoid arthritis (RA). The aim of our study was to evaluate the (pre-analytical, analytical and clinical) performance of serum calprotectin as a marker of inflammation in RA. Methods The study population included 463 rheumatologic patients (including 111 RA patients and 352 controls) who for the first time consulted a rheumatologist, 20 healthy controls and 27 patients with an infectious disease. Calprotectin was measured (using four different assays) in serum or in serum and EDTA plasma (healthy controls and infectious disease group). For rheumatologic patients, results for C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), rheumatoid factor (RF) and anti-cyclic citrullinated peptide antibody (ACPA) were available. Results Results for blood calprotectin were assay- and matrix-dependent, with higher values found in serum than in plasma. Serum calprotectin was higher in RA patients than in rheumatologic diseased controls and in healthy controls. Serum calprotectin was lower in RA patients than in patients with an infectious disease. Serum calprotectin was associated with disease activity (DAS score). The area under the curve (AUC) to discriminate RA from controls was 0.756 for CRP, 0.714 for ESR and 0.726-0.783 for calprotectin. Conclusions Our data document that calprotectin measurement is assay- and matrix-dependent. Serum calprotectin is associated with disease activity. Additional (prospective) studies are warranted to further evaluate the prognostic and diagnostic value of blood calprotectin measurements.

Serum alarmin S100A8/S100A9 levels and its potential role as biomarker in myocarditis

Aims

The alarmin S100A8/S100A9 (S100A8/A9) is released by activated monocytes/macrophages and neutrophils in the setting lymphocytic myocarditis (MC). We recently demonstrated its therapeutic potential in experimental acute MC. Now, we investigated the diagnostic relevance of S100A8/A9 serum levels in patients with suspected acute and chronic MC and in patients with heart failure without cardiac inflammation.

Methods and Results

Serum S100A8/A9 levels were analysed in patients with a recent onset of MC [≤ 30 days, n = 32; ejection fraction (EF): 45.4 ± 12.9%], dilated cardiomyopathy patients with inflammation (n = 112; EF: 29.0 ± 11.4%), or without inflammation (n = 58; EF: 26.6 ± 9.3%), and controls (n = 25; EF: 68.5 ± 4.6%), by using specific ELISAs. Blood samples were collected at Time Point 1 (T1), where also endomyocardial biopsies (EMBs) were withdrawn. Patients with a recent onset of MC showed a 4.6‐fold increase in serum S100A8/A9 levels vs. controls (MC: 1948 ± 1670 ng/mL vs. controls: 426 ± 307 ng/mL; P < 0.0001). Serum S100A8/A9 correlated with the disease activity, represented by EMB‐derived counts of inflammatory cells (CD3: r = 0.486, P = 0.0047, lymphocyte function‐associated antigen‐1: r = 0.558, P = 0.0009, macrophage‐1 antigen: r = 0.434, P = 0.013), the EMB mRNA levels of S100A8, S100A9 (r = 0.541, P = 0.002), and left ventricular ejection fraction (LVEF: r = 0.498, P = 0.0043). EMB immunofluorescence co‐stainings display macrophages/monocytes and neutrophils as the main source of S100A8 and S100A9 in recent onset MC. The diagnostic value of serum alarmin levels (cut‐off 583 ng/mL) was characterized by a specificity of 92%, a sensitivity of 90.6%, positive predictive value of 93.5%, negative predictive value of 88.5%, and an accuracy of 0.949 (95% confidence interval [0.89–1]). In a subgroup of MC patients, S100A8/A9 serum levels and EMBs at T1 (n = 12) and a follow‐up visit (T2, n = 12, mean follow‐up 8.5 months) were available. A fall of serum S100A8/A9 (T1: 2208 ± 1843 ng/mL vs. T2: 888.8 ± 513.7 ng/mL; P = 0.00052) was associated with a reduced cardiac inflammation (CD3 T1: 70.02 ± 107.4 cells per square millimetre vs. T2: 59.18 ± 182.5 cells per square millimetre; P = 0.0342, lymphocyte function‐associated antigen‐1 T1: 133.5 ± 187.1 cells per square millimetre vs. T2: 74.12 ± 190.5 cells per square millimetre; P = 0.0186, and macrophage‐1 antigen T1: 132.6 ± 129.5 cells per square millimetre vs. T2: 54.41 ± 65.16 cells per square millimetre; P = 0.0015). Serum S100A8/A9 levels were only slightly increased in patients within the chronic phase of MC and in heart failure patients without inflammation vs. controls.

Conclusions

Serum S100A8/A9 might serve as an additional tool in the diagnostic workup of suspected acute MC patients.

Evaluation of Serum Calprotectin Level and Disease Activity in Patients with Rheumatoid Arthritis

BACKGROUND

Rheumatoid Arthritis (RA) is the most common type of chronic inflammatory arthritis with unknown etiology marked by a symmetric, peripheral polyarthritis. Calprotectin also can be used as a biomarker of disease activity in inflammatory arthritis and other autoimmune diseases.

OBJECTIVES

In this study, we evaluated the association between serum calprotectin level and severity of RA activity.

METHODS

A cross-sectional study was conducted on 44 RA patients with disease flare-up. Serum samples were obtained from all patients to measure calprotectin, ESR, CRP prior to starting the treatment and after treatment period in the remission phase. Based on Disease Activity Score 28 (DAS28), disease activity was calculated.

RESULTS

Of 44 RA patients, 9(20.5%) were male and 35(79.5%) were female. The mean age of our cases was 53±1.6 years. Seventeen (38.6%) patients had moderate DAS28 and 27(61.4%) had high DAS28. The average level of calprotectin in the flare-up phase was 347.12±203.60 ng/ml and 188.04±23.58 ng/ml in the remission phase. We did not find any significant association between calprotectin and tender joint count (TJC; P=0.22), swollen joint count (SJC; P=0.87), and general health (GH; P=0.59), whereas significant associations were found between the calprotectin level and ESR (p=0.001) and DAS28 (p=0.02). The average calprotectin level in moderate DAS28 (275.21±217.96 ng/ml) was significantly lower than that in high DAS28 (392.4±183.88 ng/ml) (p=0.05).

CONCLUSION

We showed that the serum level of calprotectin can be a useful and reliable biomarker in RA activity and its severity. It also can predict treatment response.

Regulation of neutrophil pro-inflammatory functions sheds new light on the pathogenesis of rheumatoid arthritis

For more than two centuries now, rheumatoid arthritis (RA) is under investigation intending to discover successful treatment. Despite decades of scientific advances, RA is still representing a challenge for contemporary medicine. Current drug therapies allow to improve significantly the quality of life of RA patients; however, they are still insufficient to reverse tissue injury and are often generating side-effects. The difficulty arises from the considerable fluctuation of the clinical course of RA among patients, making the predictive prognosis difficult. More and more studies underline the profound influence of the neutrophil multifaceted functions in the pathogenesis of RA. This renewed interest in the complexity of neutrophil functions in RA offers new exciting opportunities for valuable therapeutic targets as well as for safe and well-tolerated RA treatments. In this review, we aim to update the recent findings on the multiple facets of neutrophils in RA, in particular their impact in promoting the RA-based inflammation through the release of the cytokine-like S100A8/A9 protein complex, as well as the importance of NETosis in the disease progression and development. Furthermore, we delve into the complex question of neutrophil heterogeneity and plasticity and discuss the emerging role of miRNAs and epigenetic markers influencing the inflammatory response of neutrophils in RA and how they could constitute the starting point for novel attractive targets in RA therapy.

Clinical significance of serum calprotectin level for the disease activity in active rheumatoid arthritis with normal C-reactive protein

BACKGROUND

There was limited data concerning predicting ability of calprotectin for disease activity of rheumatoid arthritis (RA) patients with normal C-reactive protein (CRP) level. This study was conducted to evaluate serum calprotectin levels in active RA patients and analyze its predicting value for disease activity evaluation despite normal CRP level.

METHODS

A total of 162 patients with active RA patients with normal CRP levels and 57 healthy subjects were enrolled. Serum calprotectin was measured by using a commercially available enzyme-linked immunosorbent assay (ELISA), and baseline clinical characteristics were collected. The DAS-28 scores were evaluated as indictors of disease activity. The predicting value of calprotectin in disease activity of RA patients with normal CPR was analyzed by using univariate and multivariate analysis and receiver operating characteristic curve.

RESULTS

Serum levels of calprotectin of patients with active RA were significantly higher than that of the healthy controls (3.5±3.2 vs. 2.5±0.8, P<0.01). Univariate analysis showed that serum calprotectin levels were significantly associated with the disease activity of RA. The mean serum calprotectin levels of patients with a high disease activity (DAS-28>5.1) was significantly higher than that of RA patients with low-moderate disease activity (4.3±3.5 vs. 2.6±1.1, P<0.01). Serum calprotectin levels also was evaluated as an independent predictive factor for disease activity of RA in multivariate analysis (OR, 2.31; 95% CI, 1.12-6.84; P<0.01).

CONCLUSIONS

Serum calprotectin levels can be used as a promising indictor for disease activity in active RA patients while CRP fails to do so.

Systemic calprotectin and chronic inflammatory rheumatic diseases

Calprotectin is a calcium binding protein produced by neutrophils and monocytes locally at the site of inflammation in order to trigger the innate immunity receptors. This unique characteristic makes it a good proxy for evaluation of local inflammation in chronic inflammatory rheumatic diseases. Complete data suggest, in inflammatory rheumatic diseases, a relevant role of calprotectin in the inflammatory process. The interest of serum or plasma calprotectin dosage has been studied intensively, in the current years, especially in rheumatoid arthritis, spondyloarthritis, juvenile idiopathic arthritis and ANCA associated vasculitis. Calprotectin seems to be a great candidate as biomarker to assess and monitor disease activity, to predict structural progression or response to the treatment. Calprotectin showed its ability to predict radiological progression in rheumatoid arthritis and ankylosing spondylitis. Serum calprotectin can predict the risk of relapse in ANCA associated vasculitis and the risk of inflammatory bowel disease in spondyloarthritis. Nevertheless, studies report controversial result requiring replication in other large cohort. The lack of assay standardization between studies is a problem to replicate and compare studies. In this review, we discuss on the interest of systemic calprotectin in chronic inflammatory rheumatic disease as a diagnostic, activity or prognostic biomarker.

Circulating S100 proteins effectively discriminate SLE patients from healthy controls: a cross-sectional study

S100 proteins are currently being investigated as potential diagnostic and prognostic biomarkers of several cancers and inflammatory diseases. The aims of this study were to analyse the plasma levels of S100A4, S100A8/9 and S100A12 in patients with incomplete systemic lupus erythematosus (iSLE), in patients with established SLE and in healthy controls (HCs) and to investigate the potential utility of the S100 proteins as diagnostic or activity-specific biomarkers in SLE. Plasma levels were measured by ELISA in a cross-sectional cohort study of 44 patients with SLE, 8 patients with iSLE and 43 HCs. Disease activity was assessed using the SLEDAI-2K. The mean levels of all S100 proteins were significantly higher in SLE patients compared to HCs. In iSLE patients, the levels of S100A4 and S100A12 but not S100A8/9 were also significantly higher compared to HCs. There were no significant differences in S100 levels between the iSLE and SLE patients. Plasma S100 proteins levels effectively discriminated between SLE patients and HCs. The area under the curve (AUC) for S100A4, S100A8/9 and S100A12 plasma levels was 0.989 (95% CI 0.976-1.000), 0.678 (95% CI 0.563-0.792) and 0.807 (95% CI 0.715-0.899), respectively. S100 levels did not differentiate between patients with high and low disease activity. Only the S100A12 levels were significantly associated with SLEDAI-2K and with cSLEDAI-2K. S100 proteins were significantly higher in SLE patients compared HCs and particularly S100A4 could be proposed as a potential diagnostic biomarker for SLE.

Calprotectin (S100A8/A9) should preferably be measured in EDTA-plasma; results from a longitudinal study of patients with rheumatoid arthritis

Calprotectin (S100A8/A9), a protein expressed in neutrophils and monocytes/macrophages in circulation and inflamed tissue, is associated with measures of disease activity in rheumatoid arthritis (RA) patients both when measured in ethylenediaminetetraacetic acid (EDTA)-plasma and in serum. We wanted to explore if EDTA-plasma or serum should be preferred for calprotectin as a marker of disease activity. Calprotectin was analysed in EDTA-plasma and serum by enzyme-linked immunosorbent assay (ELISA) at baseline in 141 RA patients, starting biologic disease-modifying anti-rheumatic drugs (bDMARDs), and after three months. Differences between plasma and serum levels of calprotectin were assessed by Wilcoxon signed rank test. Variability was assessed by quartile coefficient of dispersion. Spearman's test explored correlations between calprotectin in plasma and serum and between calprotectin (plasma or serum) and clinical/ultrasound (US) measures of disease activity. Bland Altman plots were used for method comparisons. Conventional inflammatory markers were evaluated for comparison. Calprotectin had similar variability when measured in plasma and serum, but there was a significant difference in concentrations between plasma and serum (p < .001). The correlation coefficients at baseline between calprotectin measured in plasma/serum and measures of disease activity were r_s = 0.62/0.46 for sum power Doppler score (PD), r_s = 0.60/0.48 for assessor's global visual analogue scale (VAS), r_s = 0.59/0.43 for sum grey scale (GS) score and r_s = 0.47/0.37 for swollen joint count of 32, all p < .001. Similar differences were found after three months. Calprotectin measured in plasma showed the strongest associations with assessments of disease activity, and EDTA-plasma should preferably be used when evaluating disease activity in RA patients.

Calprotectin in patients with chronic rheumatoid arthritis correlates with disease activity and responsiveness to methotrexate

OBJECTIVE

Calprotectin (myeloid-related protein 8/14) is elevated in inflammatory diseases and a correlation of serum calprotectin and disease activity in rheumatoid arthritis (RA) has been shown. In this study, we investigated plasma calprotectin as a disease marker in patients with chronic RA treated with methotrexate (MTX) monotherapy and compared plasma calprotectin with C-reactive protein (CRP) in this matter.

METHODS

Seventy-six patients with chronic RA were included in this open prospective study and of these 40 were included prior to initiation of MTX therapy. The patients were followed with laboratory and clinical parameters for 52-56 weeks. Plasma calprotectin was analyzed at the start of study and at various intervals. Radiographic evaluation was performed at baseline and after 17.2 months and progression in joint destruction was measured with Larsen score. The response to MTX was evaluated according to the American College of Rheumatology criteria.

RESULTS

Patients starting MTX treatment had significantly higher levels of plasma calprotectin compared to patients well established on MTX therapy (p = .008). Among the 40 patients naive to MTX, 25 responded to MTX therapy and serum calprotectin decreased significantly in these patients (p = .0007). The radiographic damage showed no relation to calprotectin.

CONCLUSIONS

Plasma calprotectin is associated with disease activity in patients with chronic RA and is more strongly correlated to MTX response compared to CRP. The role of calprotectin as a disease marker is promising and the advantages compared to CRP needs to be further investigated.

Relationship between serum calprotectin (S100A8/9) and clinical, laboratory and ultrasound parameters of disease activity in rheumatoid arthritis: A large cohort study

Background

Calprotectin may be a sensitive biomarker of rheumatoid arthritis (RA) disease activity.

Objectives

In the current study, we investigated whether calprotectin is a better biomarker than CRP for predicting clinical activity and ultrasound parameters in patients with RA.

Methods

A total of 160 patients with RA underwent clinical (swollen joint count—SJC, tender joint count—TJC, Disease Activity Score—DAS28, Clinical Disease Activity Index—CDAI, and simplified Disease Activity Index—SDAI) and ultrasound (German US7) examination. Clinical and laboratory measures were correlated with ultrasound findings using Spearman´s correlation coefficient. Differences in serum calprotectin levels in patients with variable disease activity according to the DAS28-ESR and CDAI scores were assessed using ANOVA. Multivariate regression analysis was used to determine the predictive values of calprotectin, CRP and SJC for CDAI and PD US synovitis scores.

Results

Serum calprotectin was significantly associated with DAS28-ESR (r = 0.321, p<0.001), DAS28-CRP (r = 0.346, p<0.001), SDAI (r = 0.305, p<0.001), CDAI (r = 0.279, p<0.001) scores and CRP levels (r = 0.556, p<0.001). Moreover, calprotectin was significantly correlated with GS (r = 0.379, p<0.001) and PD synovitis scores (r = 0.419, p<0.001). The multivariate regression analysis showed that calprotectin is a better predictor of the CDAI score and PD US synovitis than CRP.

Conclusions

The results of this study support an additional role of calprotectin in assessing inflammatory activity in patients with RA.

Calprotectin as a marker of inflammation in patients with early rheumatoid arthritis

Objectives

Calprotectin is an inflammatory marker of interest in rheumatoid arthritis (RA). We evaluated whether the level of calprotectin was associated with disease activity, and if it was predictive of treatment response and radiographic progression in patients with early RA.

Methods

Plasma from disease-modifying antirheumatic drug (DMARD)-naïve patients with RA fulfilling 2010 American College of Rheumatology/European League Against Rheumatism classification criteria with symptom duration <2 years was analysed for calprotectin at baseline, and after 1, 3 and 12 months. All patients received treat-to-target therapy, as part of a randomised controlled strategy trial (ARCTIC). The association between calprotectin, erythrocyte sedimentation rate (ESR) and C reactive protein (CRP) and measures of disease activity were assessed by correlations. We used likelihood ratios and logistic regression models to assess the predictive value of the baseline inflammatory markers for treatment response and radiographic damage.

Results

215 patients were included: 61% female, 82% anti-citrullinated peptide antibody positive, mean (SD) age 50.9 (13.7) years and median (25, 75 percentile) symptom duration 5.8 (2.8, 10.5) months. Calprotectin was significantly correlated with Clinical Disease Activity Index (r=0.32), ESR (r=0.50) and ultrasonography power Doppler (r=0.42) before treatment onset. After 12 months of treatment, calprotectin, but not ESR and CRP, was significantly correlated with power Doppler (r=0.27). Baseline levels of calprotectin, ESR and CRP were not predictive of treatment response, but high levels of calprotectin were associated with radiographic progression in multivariate models.

Conclusions

Calprotectin was correlated with inflammation assessed by ultrasound before and during DMARD treatment, and was also associated with radiographic progression. The data support that calprotectin may be of interest as an inflammatory marker when assessing disease activity in different stages of RA.

Trial registration number

NCT01205854; Post-results.

Autoimmune arthritis induces paired immunoglobulin-like receptor B expression on CD4+ T cells from SKG mice

The chronic, destructive autoimmune arthritis in SKG mice, which closely resembles human rheumatoid arthritis, is the result of self-reactive T cells escaping thymic deletion. Since the inhibitory receptor LIR-1 is up-regulated on auto-reactive T cells in human rheumatoid arthritis, the role of its murine ortholog PIR-B was investigated. Peripheral CD4⁺ T cells from SKG mice were found to frequently express PIR-B, and this population produces more frequently IL-17 upon in vitro stimulation compared to PIR-B^- cells. A much larger fraction of PIR-B⁺ T cells, however, was found to secret no IL-17, but IFN-γ. With regards to the clinical course of the disease, high frequencies of PIR-B⁺ CD4⁺ T cells were found to be associated with a milder course of arthritis, suggesting that the net effect of PIR-B expression is suppression of autoreactive T cells. Our results indicate that overexpression of PIR-B on IL-17-producing SKG CD4⁺ T cells might represent an effective counter-regulatory mechanism against the destructive potential of those cells. More importantly, a major population of PIR-B⁺ T cells in SKG mice appears to play an inhibitory role by way of their IFN-γ production, since high frequencies of those cells ameliorate the disease.

The predictive value of serum S100A9 and response to etanercept is not confirmed in a large UK rheumatoid arthritis cohort

Objective

The aim was to correlate protein concentrations of S100A9 in pretreatment serum samples with response to the tumour-necrosis factor (TNF) inhibitor drugs etanercept in a large UK replication cohort.

Methods

Pretreatment serum samples from patients with RA (n = 236) about to commence treatment with etanercept had S100A9 serum concentration measured using an ELISA. Following the experimental procedure, S100A9 concentrations were analysed with respect to EULAR response.

Results

No evidence of association between S100A9 concentration and EULAR response to the TNF-inhibitor biologic drug etanercept was observed following multinomial logistic regression analysis (non-responder vs moderate responder, P = 0.957; and non-responder vs good responder, P = 0.316). Furthermore, no significant associations were observed when correlating pretreatment S100A9 concentrations with clinical parameters of disease activity (P > 0.05).

Conclusion

In the largest replication cohort conducted to date, no evidence for association was observed to support the use of S100A9 as a clinical biomarker predictive of response to the TNF-inhibitor biologic drug etanercept.

Calgizzarin (S100A11): a novel inflammatory mediator associated with disease activity of rheumatoid arthritis

Background

Calgizzarin (S100A11) is a member of the S100 protein family that acts in different tumors by regulating a number of biologic functions. Recent data suggest its association with low-grade inflammation in osteoarthritis (OA). The aim of our study is to compare S100A11 expression in the synovial tissues, synovial fluid and serum of patients with rheumatoid arthritis (RA) and osteoarthritis (OA) and to characterize the potential association between S100A11 and disease activity.

Methods

S100A11 protein expression was detected in synovial tissue from patients with RA (n = 6) and patients with OA (n = 6) by immunohistochemistry and immunofluorescence. Serum and synovial fluid S100A11 levels were measured by ELISA in patients with RA (n = 40) and patients with OA (n = 34). Disease activity scores in 28 joints based on C-reactive protein (DAS28-CRP) were used to assess disease activity. Cytokine content in peripheral blood mononuclear cells (PBMCs), synovial fibroblasts (SFs) and synovial fluid was analysed by ELISA, western blotting or cytometric bead array.

Results

S100A11 expression was significantly up-regulated in the synovial lining and sublining layers (p < 0.01) and vessels (p < 0.05) of patients with RA compared to patients with OA, and was associated with fibroblasts and T cells. S100A11 was significantly increased in synovial fluid (p < 0.0001) but not in serum (p = 0.158) from patients with RA compared to patients with OA when adjusted for age and sex. Synovial fluid S100A11 correlated with DAS28 (r = 0.350, p = 0.027), serum CRP (r = 0.463, p = 0.003), synovial fluid leukocyte count (r = 0.677, p < 0.001), anti-cyclic citrullinated peptide antibodies (anti-CCP) (r = 0.424, p = 0.006) and IL-6 (r = 0.578, p = 0.002) and IL-8 (r = 0.740, p < 0.001) in synovial fluid from patients with RA. PBMCs and SFs isolated from patients with RA synthesized and spontaneously secreted higher levels of S100A11 in comparison with PBMCs and SFs from patients with OA (p = 0.011 and 0.03, respectively). S100A11 stimulated the production of the pro-inflammatory cytokine IL-6 by PBMCs (p < 0.05) and SFs (p < 0.01).

Conclusions

Our data provide the first evidence of S100A11 up-regulation and its association with inflammation and disease activity in patients with RA.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-017-1288-y) contains supplementary material, which is available to authorized users.

Calprotectin levels in rheumatoid arthritis and their correlation with disease activity: a meta-analysis

OBJECTIVE

We evaluated the relationship between calprotectin levels and rheumatoid arthritis (RA), and the correlation between plasma/serum calprotectin and RA activity.

METHODS

We searched PUBMED, EMBASE, and Cochrane databases and performed meta-analyses comparing plasma/serum or synovial fluid calprotectin levels in RA patients and controls, and correlation coefficients between calprotectin levels and disease activity for 28 joints (DAS28) as well as C-reactive protein (CRP) in RA patients.

RESULTS

Sixteen studies including 849 RA patients and 266 controls were available for meta-analysis. Meta-analysis showed that calprotectin levels were significantly higher in the RA group than in the control group (SMD = 2.337, 95% CI = 1.544-3.130, p < 1.0 × 10^-8). Stratification by rheumatoid factor (RF) status revealed significantly elevated calprotectin levels in the RF-positive RA group compared to that of the RF-negative RA group (SMD = 0.574, 95% CI = 0.345-0.804, p = 9.2 × 10^-7). Meta-analysis of correlation coefficients identified a significant positive correlation between calprotectin levels and CRP or DAS28 (correlation coefficient for CRP = 0.566, 95% CI = 0.512-0.615, p < 1.0 × 10^-8; correlation coefficient for DAS28 = 0.438, 95% CI = 0.269-0.518, p = 2.5 × 10^-6). Calprotectin levels in synovial fluid were significantly higher in the RA group than in the control group (SMD = 2.891, 95% CI = 1.067-4.715, p = 0.002).

CONCLUSIONS

Our meta-analysis demonstrates that circulating and synovial fluid calprotectin levels are high in patients with RA, and that circulating calprotectin levels positively correlate with RA activity.

Calprotectin (S100A8/A9) has the strongest association with ultrasound-detected synovitis and predicts response to biologic treatment: results from a longitudinal study of patients with established rheumatoid arthritis

BACKGROUND

Calprotectin (S100A8/A9 or MRP8/14) and S100A12 (leukocyte-derived proteins), interleukin 6 (IL-6) and vascular endothelial growth factor (VEGF) are markers of inflammation and angiogenesis. Ultrasound (US) is sensitive for detection of greyscale synovitis and power Doppler (PD) vascularization. The objective of the present study was to explore the associations between calprotectin, S100A12, IL-6, VEGF, erythrocyte sedimentation rate, C-reactive protein and a comprehensive US assessment in patients with rheumatoid arthritis (RA) starting biologic disease-modifying anti-rheumatic drug (bDMARD) treatment.

METHODS

A total of 141 patients with RA were assessed by US, clinical examination and biomarker levels at baseline and at 1, 2, 3, 6 and 12 months after initiation of bDMARDs. US assessment of 36 joints and 4 tendon sheaths were scored semi-quantitatively (0-3 scale). European League Against Rheumatism (EULAR) response was calculated. Statistical assessments performed to explore the associations between biomarkers and US sum scores included Spearman's rank correlation analysis as well as linear and linear mixed model regression analyses.

RESULTS

Calprotectin showed the overall strongest correlations with both US sum scores (r _s = 0.25-0.62) and swollen joint counts (of 32) (r _s = 0.24-0.47) (p < 0.05 at all examinations). An association with US sum scores remained after we adjusted for age, sex, disease duration and all the other markers in a regression analysis at baseline. Decreased calprotectin at the first month was predictive of both EULAR response (p ≤ 0.001) and decreased sum PD scores at 3, 6 and 12 months (p ≤ 0.05).

CONCLUSIONS

Calprotectin had the highest association with US synovitis and predicted treatment response. It may thus be considered as a marker for evaluating inflammation and responsiveness in patients with RA on bDMARD treatment.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry (ANZCTR) identifier: ACTRN12610000284066 . Registered on 8 April 2010 (retrospectively registered).

Serum Calprotectin in Rheumatoid Arthritis: A Promising Diagnostic Marker, How Far Is It Related to Activity and Sonographic Findings?

Background:

In the past 2 decades, there has been increasing interest in calprotectin. It is released and detected in serum and body fluids as a potentially useful clinical inflammatory marker. The protein has been described in synovial tissue in rheumatoid arthritis (RA) patients, specifically in the lining layer adjacent to the cartilage–pannus junction, which is the primary site of cartilage destruction and bone erosion. Assessment of inflammatory activity in RA is of pivotal importance for the optimal treatment. Our aim in this study is to measure the serum calprotectin levels in RA patients and to assess its association—if there is any—with disease activity score and radiological findings using the musculoskeletal ultrasound.

Patients and methods:

In our case control study, we included 44 RA patients (Group I) and 20 age- and sex-matched healthy volunteers who served as the control group (Group II). Both groups were subjected to full history taking and thorough clinical examination. Assessment of RA disease activity state was done for all RA patients using the Disease Activity Score 28. Laboratory investigations included the measurement of complete blood cell count, erythrocyte sedimentation rate, C-reactive protein, rheumatoid factor, anticitrullinated peptide antibodies, kidney, liver functions; serum calprotectin levels were determined using enzyme-linked immunosorbent assay and radiological joint assessment was done using musculoskeletal ultrasound score.

Results:

There was a statistically significant elevation of serum calprotectin levels among RA patients when compared with healthy controls. Statistically significant correlations were also found between serum calprotectin and the ultrasound grading score, Disease Activity Score 28, and erythrocyte sedimentation rate, which reflect the degree of inflammatory activity in the affected joints in RA patients. Moreover, the study yielded a significant correlation between serum calprotectin levels and rheumatoid autoantibodies (rheumatoid factor and anticitrulli-nated peptide antibodies), which are strong predictors of the aggressiveness of the disease. Serum calprotectin at a cutoff level of 93.9 μg/dL had 88.6% sensitivity and 100% specificity for diagnosis of RA.

Conclusion:

Calprotectin was found to have high association with laboratory and ultrasonography markers of inflammation in RA patients, so it is recommended for use as a marker of inflammatory activity in RA patients especially for the follow-up of patients on biological therapy to assess its efficacy.

S100A8+ stroma cells predict a good prognosis and inhibit aggressiveness in colorectal carcinoma

Gene microarray and bioinformatic analysis showed that S100A8 was more abundant in the stroma surrounding tumor buddings (TBs) than in the stroma surrounding primary tumor cells in colorectal carcinomas. Here, S100A8⁺ cells in 419 colorectal carcinoma samples were stained by immunohistochemistry and counted using Image-pro plus 6.0. TBs were also counted and biomarkers associated with the epithelial-mesenchymal transition and apoptosis were assessed by immunohistochemistry. We evaluated the association between S100A8⁺ cells and clinico-pathological variables as well as survival. Migration and invasion as well as biomarkers of the epithelial-mesenchymal transition and apoptosis were tested in CRC cells, treated with graded concentrations of recombinant human S100A8 protein. We found that the density of S100A8⁺ cells in the tumor invasive front (S100A8⁺_TIF) clearly distinguished patients with 5-y survival from those who did not survive (p = 0.01). The S100A8⁺-associated tumor budding (SATB) index determined by the S100A8⁺_TIF and TB was an independent predictor of overall survival (p = 0.001) other than the S100A8⁺_TIF or TB alone. Migration and invasion properties of CRC cells were inhibited by recombinant human S100A8 treatment. The particular S100A8⁺ cells in the stroma were associated with important biomarkers of the epithelial-mesenchymal transition (E-cadherin and SNAIL) and apoptosis (BCL2). In conclusion, S100A8⁺ cells in the stroma predict a good prognosis in colorectal carcinoma. An index combining S100A8⁺ cells and TB independently predicts survival. Recombinant human S100A8 inhibited CRC cell migration and invasion, which was involved in epithelial-mesenchymal transition (E-cadherin and SNAIL) and apoptosis (BCL2).

Clinical improvement and reduction in serum calprotectin levels after an intensive exercise programme for patients with ankylosing spondylitis and non-radiographic axial spondyloarthritis

Background

The efficacy of exercise therapy for ankylosing spondylitis (AS) is well-documented, but dearth of information is for non-radiographic axial spondyloarthritis (nr-axSpA).

Biomarkers like serum calprotectin, interleukins IL-6, IL-17 and tumour necrosis factor (TNF)-α may reflect the disease activity of axial spondyloarthritis (axSpA). In this study, we investigated clinical and laboratory parameters of both axSpA subgroups in response to intensive physical exercise.

Methods

Altogether, 46 patients with axSpA, characterised according to the Assessment of SpondyloArthritis International Society criteria as having nr-axSpA or AS underwent 6-month exercise programme. Clinical outcomes of disease activity, Bath AS Disease Activity Index (BASDAI), AS Disease Activity Index (ASDAS-CRP), mobility, Bath AS Metrology Index (BASMI) and function, Bath AS Functional Index (BASFI) were evaluated at baseline and at the end of the exercise programme. Serum IL-6 and IL-17, TNF-α and calprotectin were measured via ELISA. The clinical and laboratory data of 29 control axSpA patients were used for the evaluation of the results.

Results

In all axSpA patients, the ASDAS-CRP (2.10 ± 0.12 to 1.84 ± 0.11, p <0.01) and BASMI (1.28 ± 0.14 to 0.66 ± 0.84, p <0.0001) improved after 6 months of exercise therapy. There was a significant improvement in the ASDAS-CRP in the nr-axSpA subgroup (2.01 ± 0.19 to 1.73 ± 0.16, p <0.05) and in the BASMI in both, the nr-axSpA and the AS subgroups (1.09 ± 0.12 to 0.47 ± 0.08, p <0.0001 and 1.43 ± 0.24 to 0.82 ± 0.23, p <0.0001, respectively). Both, ASDAS-CRP and BASDAI, were significantly improved in the exercise axSpA group compared to the control axSpA group (mean -0.26 vs. -0.13 and -0.49 vs. 0.12, respectively, all p <0.05). Only calprotectin was significantly reduced after the exercise programme in nr-axSpA and AS patients (from 2379.0 ± 243.20 to 1779.0 ± 138.30 μg/mL and from 2430.0 ± 269.70 to 1816.0 ± 148.20 μg/mL, respectively, all p <0.01). The change in calprotectin was more profound in the axSpA intervention group (mean -604.56) than in the control axSpA (mean -149.28, p <0.05).

Conclusion

This study demonstrated similar efficacy for an intensive exercise programme in both nr-axSpA and AS patients. A significant decrease in serum calprotectin levels in both subgroups of axSpA patients after the exercise programme reflected an improvement in the disease activity and spinal mobility.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-016-1180-1) contains supplementary material, which is available to authorized users.

Serum Calprotectin Discriminates Subclinical Disease Activity from Ultrasound-Defined Remission in Patients with Rheumatoid Arthritis in Clinical Remission

OBJECTIVE

Clinical remission in some patients with rheumatoid arthritis (RA) may be associated with ongoing synovial inflammation that is not always detectable on clinical examination or reflected by laboratory tests but can be visualized by musculoskeletal ultrasound. The goal of our study was to determine the levels of serum calprotectin, a major leukocyte protein, in patients with RA in clinical remission and to investigate the ability of serum calprotectin levels to distinguish patients in ultrasound-defined remission from those with residual ultrasound subclinical inflammation.

METHODS

Seventy RA patients in clinical remission underwent clinical and ultrasound examination. Ultrasound examination was performed according to the German US7 score. Ultrasound remission was defined as grey scale (GS) range 0-1 and power Doppler (PD) range 0. The levels of serum calprotectin and C-reactive protein (CRP) were determined. The discriminatory capacity of calprotectin and CRP in detecting residual ultrasound inflammation was assessed using ROC curves.

RESULTS

The total number of patients fulfilling the DAS28-ESR, DAS28-CRP, SDAI and CDAI remission criteria was 58, 67, 32 and 31, respectively. Residual synovial inflammation was found in 58-67% of the patients who fulfilled at least one set of clinical remission criteria. Calprotectin levels were significantly higher in patients with residual synovial inflammation than in those with ultrasound-defined remission (mean 2.5±1.3 vs. 1.7±0.8 μg/mL, p<0.005). Using ultrasound-defined remission criteria, calprotectin had an AUC of 0.692, p<0.05 using DAS28-ESR remission criteria and an AUC of 0.712, p<0.005 using DAS28-CRP remission criteria. Calprotectin correctly distinguished ultrasound remission from subclinical activity in 70% of patients. CRP (AUC DAS28-ESR = 0.494, p = NS; AUC DAS28-CRP = 0.498, p = NS) had lower and insignificant discriminatory capacity.

CONCLUSION

The present study demonstrates the potential of calprotectin to distinguish RA patients in both clinical and ultrasound-defined remission from patients in clinical remission but with residual subclinical disease activity.

Integrative analysis for identification of shared markers from various functional cells/tissues for rheumatoid arthritis

Rheumatoid arthritis (RA) is a systemic autoimmune disease. So far, it is unclear whether there exist common RA-related genes shared in different tissues/cells. In this study, we conducted an integrative analysis on multiple datasets to identify potential shared genes that are significant in multiple tissues/cells for RA. Seven microarray gene expression datasets representing various RA-related tissues/cells were downloaded from the Gene Expression Omnibus (GEO). Statistical analyses, testing both marginal and joint effects, were conducted to identify significant genes shared in various samples. Followed-up analyses were conducted on functional annotation clustering analysis, protein-protein interaction (PPI) analysis, gene-based association analysis, and ELISA validation analysis in in-house samples. We identified 18 shared significant genes, which were mainly involved in the immune response and chemokine signaling pathway. Among the 18 genes, eight genes (PPBP, PF4, HLA-F, S100A8, RNASEH2A, P2RY6, JAG2, and PCBP1) interact with known RA genes. Two genes (HLA-F and PCBP1) are significant in gene-based association analysis (P = 1.03E-31, P = 1.30E-2, respectively). Additionally, PCBP1 also showed differential protein expression levels in in-house case-control plasma samples (P = 2.60E-2). This study represented the first effort to identify shared RA markers from different functional cells or tissues. The results suggested that one of the shared genes, i.e., PCBP1, is a promising biomarker for RA.

Evaluation of Serum S100A8/S100A9 Levels in Patients with Autoimmune Thyroid Diseases

BACKGROUND

The correlation of S100A8/S100A9 with various inflammatory conditions, including autoimmune diseases have been reported. There is no study investigating the levels of S100A8/S100A9 in autoimmune thyroid diseases (AITD).

AIMS

We aimed to evaluate the level of serum S100A8/S100A9 in AITD.

STUDY DESIGN

Case control study.

METHODS

Fifty patients with AITD (25 Hashimoto's thyroiditis (HT) and 25 Graves' disease (GD)) were included in the study. Twenty seven healthy subjects participated as a control group. Blood samples were obtained in the 3 months after the initiation of medical treatment. Serum levels of total antioxidant status (TAS), total oxidative status (TOS), total free sulfhydryl (SH), lipid hydroperoxide (LOOH) and S100A8/S100A9 were analyzed.

RESULTS

The patients with AITD had significantly higher S100A8/S100A9, OSI, LOOH and TOS levels than the healthy control group. There was no significant difference between GD and HT patients in terms of S100A8/S100A9, TOS and OSI levels. S100A8/S100A9 level was positively correlated with LOOH, TOS and OSI levels but negatively correlated with -SH level in the patients with AITD.

CONCLUSION

Serum S100A8/S100A9 levels were increased in patients with AITD and positively correlated with LOOH, TOS and OSI whereas negatively correlated with SH.

Calprotectin levels in patients with rheumatoid arthritis to assess and association with exercise treatment

Rheumatoid arthritis (RA) is a chronic, inflammatory, and autoimmune disease that can cause permanent joint damage. In our study, we aim to analyze the change in calprotectin levels following the low-density exercise levels applied to the patients with RA. Twenty-eight patients with RA and 30 healthy controls were included in this study. To evaluate the activity of disease in RA, scores of disease activity that has increased (DAS-28) are figured. Calprotectin, nitric oxide (NO), white blood cell (WBC) count, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and rheumatoid factor (RF) levels are tested as the laboratory evaluation. Calprotectin, NO, CRP, ESR, WBC, and RF levels were significantly higher in the patient group compared to the control group (p < 0.01, p < 0.001, p < 0.01, p < 0.01, p < 0.01, and p < 0.05, respectively). In correlation analysis applied to the patient group with RA, there has been determined a positive relation with calprotectin, and DAS-28, CRP, NO, RF, and WBC (p < 0.001, p < 0.05, p < 0.001, p < 0.05, and p < 0.05, respectively). In result of the low-density exercise treatment applied to patients with RA for 8 weeks, there has been determined a significant decrease in calprotectin, DAS-28, NO, CRP, ESR, and RF levels (p < 0.05, p < 0.001, p < 0.01, p < 0.05, p < 0.05, and p < 0.05, respectively). As a result, a significant relation is found between RA disease activity and calprotectin levels and other inflammatory parameters. At the same time, it shows that calprotectin which is a significant indicator of local inflammation can be used as a good identifier in following up exercise treatment.

Myeloid-related Protein 8/14 Levels in Rheumatoid Arthritis: Marker of Disease Activity and Response to Methotrexate

Objective.

Myeloid-related proteins (MRP) 8/14 belong to a family of calcium-binding proteins produced by myeloid cells. Baseline serum levels of MRP8/14 have been shown to predict response to biologicals in rheumatoid arthritis (RA). Because methotrexate (MTX) is the first-line therapy in RA, we studied whether MRP8/14 levels can predict response to MTX.

Methods.

Patients with active RA disease who were naive to disease-modifying antirheumatic drugs were enrolled. All patients were treated with MTX only, to a maximum of 25 mg/week or the maximal tolerated dose. At 4 months, the European League Against Rheumatism response was assessed. All patients who needed rescue therapy after 2 months or who did not respond at 4 months were classified as nonresponders.

Results.

Ninety patients were enrolled, of whom 3 discontinued MTX within 4–6 weeks, so 87 patients were analyzed [74 women, median (interquartile range; IQR) for the Disease Activity Score at 28 joints (DAS28) was 4.43 (4.1–5.1)]. The median (IQR) serum MRP8/14 level at baseline was 19.95 µg/ml (11.49–39.06). The serum MRP8/14 had good correlation with DAS28-C-reactive protein (CRP; r = 0.35, p = 0.001). The MRP8/14 levels fell significantly after 4 months of treatment (10.28 µg/ml, 5.95–16.05, p < 0.001). Among 87 patients, 69 were responders. The median (IQR) baseline level of MRP8/14 was higher among responders compared with nonresponders: 23.99 µg/ml (15.39–42.75) versus 9.58 µg/ml (6.11–24.93, p = 0.00250). The levels declined in the responders, from 23.99 µg/ml (15.39–42.75) to 10.41 µg/ml (5.83–15.61, p < 0.001), but not in the nonresponders, from 9.58 µg/ml (6.11–24.93) to 9.19 µg/ml (7.74–21.96, p = 0.687). Receiver-operation characteristic analysis showed that MRP8/14 was a better predictor of response than CRP and erythrocyte sedimentation rate, especially with early disease onset (< 1-yr duration).

Conclusion.

MRP8/14 is a good marker of disease activity in RA, and higher levels predict response to MTX.

Calprotectin (S100A8/A9) and S100A12 are associated with measures of disease activity in a longitudinal study of patients with rheumatoid arthritis treated with infliximab

OBJECTIVES

The pro-inflammatory proteins calprotectin (a heterocomplex of S100A8/A9) and S100A12 have been associated with disease activity in rheumatoid arthritis (RA). The aim of this study was to compare their potential as biomarkers in a prospective study of RA patients starting with infliximab as their first biological disease-modifying anti-rheumatic drug (DMARD).

METHOD

Thirty-nine RA patients were examined and serum samples collected when starting with infliximab and after 3, 6, and 12 months. Calprotectin and S100A12 were analysed by enzyme-linked immunosorbent assays (ELISAs) and, together with C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR), measured at all time points. A disease activity score of 28 joints (DAS28) was calculated. Radiographs of the hands, wrists, and feet were taken at baseline and after 3 years, and assessed according to the modified Sharp/van der Heijde (SvH) score. Responsiveness was evaluated according to the European League of Associations for Rheumatology (EULAR) response criteria based on 28 joints.

RESULTS

Both S100 proteins were significantly higher in seropositive than in seronegative patients (p = 0.01). Calprotectin correlated significantly with CRP (ρ = 0.51-0.75), ESR (ρ = 0.32-0.52), and DAS28 (ρ = 0.32-0.62). S100A12 correlated with calprotectin (ρ = 0.62-0.77) and CRP (ρ = 0.32-0.63). The S100 proteins, and especially calprotectin (ρ = 0.23-0.39), showed weak associations with radiographic progression, unlike CRP/ESR. None of the S100 proteins could predict responsiveness.

CONCLUSIONS

Calprotectin showed the strongest correlation with measures of disease activity and may be better than S100A12 when evaluating disease activity in RA patients. More extensive studies are needed to further compare the predictive value of the S100 proteins relative to radiographic progression.

High level of fecal calprotectin at age 2 months as a marker of intestinal inflammation predicts atopic dermatitis and asthma by age 6

BACKGROUND

Gut microbiota and intestinal inflammation regulate the development of immune-mediated diseases, such as allergies. Fecal calprotectin is a biomarker of intestinal inflammation.

OBJECTIVE

We evaluated the association of early-age fecal calprotectin levels to the later development of allergic diseases in children from farming and non-farming environments and further studied the effect of gut microbiota on the fecal calprotectin levels.

METHODS

Fecal calprotectin was measured from 758 infants participating in the PASTURE study at the age of 2 months using the ELISA method. Serum-specific IgE levels were measured at 6 years of age. Data of environmental factors, doctor-diagnosed atopic dermatitis (AD) and asthma were collected by questionnaire. Multivariate logistic regression models were used for analysis. The composition of fecal microbiota was analysed in a subgroup of 120 infants with 16S rRNA pyrosequencing. The effect of Escherichia coli lipopolysaccharide (LPS) on in vitro monocyte IL-10 secretion was studied by flow cytometry.

RESULTS

The infants with high fecal calprotectin levels at 2 months, that is above the 90th percentile, had an increased risk of developing AD and asthma/asthmatic bronchitis by the age of 6 years (aOR 2.02 (1.06-3.85) and 2.41 (1.25-4.64), respectively). High fecal calprotectin levels correlated negatively with fecal Escherichia. LPS from E. coli stimulated production of IL-10 in monocytes.

CONCLUSION AND CLINICAL RELEVANCE

High degree intestinal inflammation at 2 months of age, detected as high fecal calprotectin, predicted asthma and AD by the age of 6 years and was linked to low abundance of fecal Escherichia. Impaired IL-10 activation due to the lack of colonization with E. coli could explain the intestinal inflammation associated high fecal calprotectin and later risk of asthma and AD. Our results have implications for the design of probiotic treatments and suggest that early intestinal colonization has long-term health effects.

Calprotectin in rheumatic diseases

Calprotectin is a heterodimer formed by two proteins, S100A8 and S100A9, which are mainly produced by activated monocytes and neutrophils in the circulation and in inflamed tissues. The implication of calprotectin in the inflammatory process has already been demonstrated, but its role in the pathogenesis, diagnosis, and monitoring of rheumatic diseases has gained great attention in recent years. Calprotectin, being stable at room temperature, is a candidate biomarker for the follow-up of disease activity in many autoimmune disorders, where it can predict response to treatment or disease relapse. There is evidence that a number of immunomodulators, including TNF-α inhibitors, may reduce calprotectin expression. S100A8 and S100A9 have a potential role as a target of treatment in murine models of autoimmune disorders, since the direct or indirect blockade of these proteins results in amelioration of the disease process. In this review, we will go over the biologic functions of calprotectin which might be involved in the etiology of rheumatic disorders. We will also report evidence of its potential use as a disease biomarker. Impact statement Calprotectin is an acute-phase protein produced by monocytes and neutrophils in the circulation and inflamed tissues. Calprotectin seems to be more sensitive than CRP, being able to detect minimal residual inflammation and is a candidate biomarker in inflammatory diseases. High serum levels are associated with some severe manifestations of rheumatic diseases, such as glomerulonephritis and lung fibrosis. Calprotectin levels in other fluids, such as saliva and synovial fluid, might be helpful in the diagnosis of rheumatic diseases. Of interest is also the potential role of calprotectin as a target of treatment.

Biomarkers in Remission According to Different Criteria in Patients with Rheumatoid Arthritis

OBJECTIVE

Remission is the primary aim in the treatment of patients with rheumatoid arthritis (RA). In this study, we aimed to evaluate biomarker profiles of patients in remission by different criteria and compare these profiles with controls.

METHODS

Serum levels of calprotectin, interleukin 6 (IL-6), type II collagen helical peptide, C-terminal crosslinking telopeptide of type I collagen generated by matrix metalloproteinases (ICTP), matrix metalloproteinase 3 (MMP-3), resistin, and leptin were measured by ELISA in 80 patients. The patients were in Disease Activity Score at 28 joints with erythrocyte sedimentation rate (DAS28-ESR) remission, and had these characteristics: female/male 54/26, mean age 51.4 ± 12.1 years, mean disease duration 11.4 ± 8.1 years, rheumatoid factor positivity 68.7% (n = 55), anticyclic citrullinated peptide positivity 60.7% (n = 48). These patients were also evaluated for the American College of Rheumatology/European League Against Rheumatism (Boolean) and Simple Disease Activity Index (SDAI) remissions. Additionally, 80 age-, sex-, and comorbidity-matched individuals without rheumatic diseases were included in the study as controls.

RESULTS

At recruitment of 80 patients in DAS28 remission, 33 patients (41.2%) were found in Boolean remission and 39 patients (48.7%) were in SDAI remission. Serum MMP-3, ICTP, resistin, and IL-6 levels of the 80 patients in DAS28 remission were statistically significantly higher than the controls. Patients in Boolean and SDAI remissions had significantly higher serum ICTP, resistin, and IL-6 levels in comparison with the controls.

CONCLUSION

The 3 commonly used remission criteria of RA are almost similar with regard to patients' biomarker levels. Biomarker profiles of patients may provide complementary information to clinical evaluation of remission and may help to determine the patients under the risk of progression.

Serum calprotectin (S100A8/9): an independent predictor of ultrasound synovitis in patients with rheumatoid arthritis

Introduction

Calprotectin, a heterodimeric complex of S100A8/9 (MRP8/14), has been proposed as an important serum biomarker that reflects disease activity and structural joint damage in rheumatoid arthritis (RA). The objective of this cross-sectional study was to test the hypothesis that calprotectin is associated with clinical and ultrasound-determined disease activity in patients with RA.

Methods

A total of 37 patients with RA (including 24 females, a mean disease duration of 20 months) underwent a clinical examination and 7-joint ultrasound score (German US-7) of the clinically dominant hand and foot to assess synovitis by grey-scale (GS) and synovial vascularity by power Doppler (PD) ultrasound using semiquantitative 0–3 grading. The levels of serum calprotectin and C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) were determined at the time of the ultrasound assessment. We analysed the relationship between serum calprotectin level, traditional inflammatory markers, and ultrasound-determined synovitis.

Results

The levels of serum calprotectin were significantly correlated with swollen joint count (r = 0.465, p < 0.005), DAS28-ESR (r = 0.430, p < 0.01), ESR (r = 0.370, p < 0.05) and, in particular, CRP (r = 0.629, p < 0.001). Calprotectin was significantly associated with GS (r = 0.359, p < 0.05) and PD synovitis scores (r = 0.497, p < 0.005). Using multivariate regression analysis, calprotectin, adjusted for age and sex, was a better predictor of PD synovitis score (R² = 0.765, p < 0.001) than CRP (R² = 0.496, p < 0.001).

Conclusions

The serum levels of calprotectin are significantly associated with clinical, laboratory and ultrasound assessments of RA disease activity. These results suggest that calprotectin might be superior to CRP for monitoring ultrasound-determined synovial inflammation in RA patients.

Genetic and genomic markers of anti-TNF treatment response in rheumatoid arthritis

Despite the success of anti-TNF drugs in the treatment of rheumatoid arthritis, a significant rate of nonresponse remains. Current clinical factors confer little power for predicting response and, in current practice, an unsatisfactory ‘trial and error’ approach governs therapeutic decisions. Candidate gene and unbiased genome-wide investigations have sought to identify genetic biomarkers that predict who will respond to anti-TNF drugs before the drug is administered. To date, few studies have yielded robust associations; herein, we discuss currently identified associations and the issues that need to be addressed in future investigations including insufficient power and an inadequate measure of disease activity. The potential for alternative predictors of anti-TNF therapy response from transcriptomic and epigenetic data will also be explored.

Neutrophil-to-lymphocyte ratio, calprotectin and YKL-40 in patients with chronic obstructive pulmonary disease: correlations and 5-year mortality - a cohort study

Background

Chronic obstructive pulmonary disease (COPD) is characterized by chronic inflammation and progressive decline in pulmonary function. Neutrophil-to-lymphocyte ratio (NLR), YKL-40 and calprotectin are biomarkers of inflammation and predict mortality in patients with different inflammatory diseases. We aimed to investigate the correlation between levels of these three biomarkers and neutrophil granulocyte and lymphocyte count in patients with moderate to very severe COPD stratified by use of systemic glucocorticoids. Furthermore, we studied the ability of these biomarkers to predict all-cause mortality.

Methods

386 patients with moderate to very severe COPD were followed prospectively for 10 years. Patients were divided into two groups according to systemic glucocorticoid use at baseline. Correlations between biomarkers were assessed by Spearman’s Rho, and mortality was evaluated in uni- and multivariate Cox regression analyses with hazard ratios (HR) and 95% confidence intervals (CI).

Results

Plasma calprotectin was positively correlated with neutrophil granulocyte count and NLR. No significant association was found between plasma YKL-40 and the cellular biomarkers, irrespective of glucocorticoid treatment. In the group not treated with systemic glucocorticoids, plasma calprotectin [HR 1.002 (95% CI 1.000 – 1.004)], NLR [HR 1.090 (1.036 – 1.148)] and lymphocyte count [HR 0.667 (0.522 – 0.851)] were significantly associated with higher mortality. In the group treated with systemic glucocorticoids, higher plasma YKL-40 was significantly associated with mortality in univariate Cox regression analysis [HR 1.006 (1.003 – 1.008)].

Conclusions

Calprotectin was related to neutrophil granulocyte count and NLR in patients with moderate to very severe COPD in stable phase and not in treatment with systemic glucocorticoids. Lymphopenia, higher plasma calprotectin and higher NLR were independent predictors of increased all-cause mortality in this group. Our data also suggests that treatment with systemic glucocorticoids has a significant impact on the ability of inflammatory biomarkers to predict all-cause mortality.

Trial registration

ClinicalTrials.gov NCT00132860.

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.

Identification of S100A9 as biomarker of responsiveness to the methotrexate/etanercept combination in rheumatoid arthritis using a proteomic approach

OBJECTIVES

One way to optimize the drug prescription in rheumatoid arthritis (RA) is to identify predictive biomarkers of drug responsiveness. Here, we investigated the potential "theranostic" value of proteins of the S100 family by monitoring levels of both S100A8 and S100A9 in blood samples from RA patients.

DESIGN

For proteomic analysis, peripheral blood mononuclear cells (PBMC) and serum samples were collected in patients prior to initiation of the methotrexate/etanercept (MTX/ETA) combination. Firstly, relative mass spectrometry (MS) quantification focusing on S100A8 and S100A9 proteins was carried out from PBMCs samples to identify potential biomarkers. The same approach was also performed from serum samples from responder (R) and non responder (NR) patients. Finally, to confirm these results, an absolute quantification of S100A8, S100A9 proteins and calprotectin (heterodimer of S100A8/S100A9) was carried out on the serum samples using ELISA.

RESULTS

MS analyses revealed that both S100A8 and S100A9 proteins were significantly accumulated in PBMC from responders. In contrast to PBMC, only the S100A9 protein was significantly overexpressed in the serum of R patients. Absolute quantification by ELISA confirmed this result and pointed out a similar expression level of S100A8 protein and calprotectin in sera from both R and NR groups. Thus, the S100A9 protein revealed to be predictive of MTX/ETA responsiveness, contrarily to parameters of inflammation and auto-antibodies which did not allow significant discrimination.

CONCLUSION

This is the first report of an overexpression of S100A9 protein in both PBMCs and serum of patients with subsequent response to the MTX/ETA combination. This protein thus represents an interesting biomarker candidate of therapeutic response in RA.

High levels of metastasis-inducing S100A4 protein and treatment outcome in early rheumatoid arthritis: data from the PERAC cohort

Abstract The aim of this study was to evaluate the role of S100A4 as a biomarker in patients with early rheumatoid arthritis (RA). S100A4 levels were measured in 59 patients with early RA and in 41 healthy controls. The association between the S100A4 levels and the treatment outcome after 12 months was determined using multivariate regression analysis. Serum S100A4 levels were significantly higher in the patients with early RA than in the healthy subjects and significantly decreased after 3 months of treatment. Diseases activity at 12 months was significantly higher in female patients who had initially high levels of S100A4. Persistently high S100A4 levels predicted poor treatment outcome and S100A4 may thus represent promising biomarker for assessing treatment response in patients with RA.

Decrease in serum interleukin-21 levels is associated with disease activity improvement in patients with recent-onset rheumatoid arthritis

Interleukin-21 (IL-21) plays an important role in the pathogenesis of rheumatoid arthritis (RA). The aim of our study was to assess serum levels of IL-21 in patients with recent-onset RA in relation to disease activity and response to treatment. We analyzed serum levels of IL-21 in 51 RA patients, both before and 12 weeks after the initiation of treatment and in 36 healthy individuals. Disease activity was assessed at baseline and at weeks 12 and 24 using the Disease Activity Score for 28 joints, serum levels of C-reactive protein, and the total swollen joint count. We found that IL-21 levels were not increased in patients with recent-onset RA compared with healthy controls, but they had significantly decreased from baseline to week 12 during treatment. Baseline levels of IL-21 significantly correlated with measures of disease activity (p<0.02 for all). Although IL-21 levels did not predict achievement of remission, decrease in IL-21 levels correlated with improvement in disease activity after 12 weeks (p<0.02) and also after 24 weeks (p<0.04) of treatment. Our data suggest that circulating IL-21 levels may serve as a biomarker of disease activity and better outcome in early phase of RA.