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

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.

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.

Calprotectin (S100A8/S100A9) detects inflammatory activity in rheumatoid arthritis patients receiving tocilizumab therapy

Background

Assessing serological inflammation is difficult in tocilizumab (TCZ)-treated rheumatoid arthritis (RA) patients, as standard inflammation parameters, like erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP), are influenced by interleukin-6-receptor inhibition. Calprotectin in the serum, also named S100A8/S100A9, might be a more useful inflammation parameter in TCZ-treated patients.

Methods

Sixty-nine RA patients taking TCZ were included. Serum-calprotectin levels were assessed, as well as ESR, CRP, need for a change in disease-modifying anti-rheumatic drugs due to RA activity (= active RA), and the RA clinical disease activity score (CDAI). Forty-five RA patients taking tumor-necrosis factor-inhibitors (TNFi) were investigated for the same parameters.

Results

TCZ-treated patients with active RA had higher calprotectin values than not active RA patients (4155.5 [inter quartile range 1865.3–6068.3] vs 1040.0 [676.0–1638.0] ng/ml, P < 0.001). A calprotectin cut-off value of 1916.5 ng/ml resulted in a sensitivity and specificity of 80.0 %, respectively, for the detection of RA disease activity. Calprotectin values correlated with CDAI-scores (r = 0.228; P = 0.011). ESR and CRP were less suitable to detect RA activity in TCZ-treated patients. Also TNFi-treated patients with active RA had higher calprotectin values compared to not active RA (5422.0 [3749.0–8150.8] vs 1845.0 [832.0–2569.0] ng/ml, P < 0.001). The calprotectin value with the best sensitivity and specificity for detecting RA activity was 3690.5 ng/ml among TNFi-treated patients.

Conclusion

Calprotectin in the serum can be a useful inflammation parameter despite TCZ-treatment.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13075-022-02887-7.

Analytical and clinical evaluation of DiaSorin Liaison® Calprotectin fecal assay adapted for serum samples

Background

Calprotectin is a calcium‐binding protein that can be measured in serum, plasma, and feces. Increased serum and plasma calprotectin concentrations have been found in chronic inflammatory rheumatic disorders. An analytical and clinical evaluation of the DiaSorin Liaison® fecal Calprotectin assay using LIAISON® XL was performed.

Methods

The protocol included an analytical and clinical evaluation in which imprecision, the linearity of dilution, differences between serum and plasma samples and method comparison with CalproLab™ ELISA kit were assessed. Serum calprotectin concentrations in active (n = 26) and remission (n = 23) rheumatoid arthritis (RA) patients were compared.

Results

The intra‐day and inter‐day analytical imprecision CVs ranged from 2.9% to 4.0% and 2.7% to 10.4%, respectively. Correlation between measured and expected values was high (R > 0.99), indicating good linearity. The Wilcoxon signed‐rank test showed that serum and plasma matched samples presented statistically significant differences (p < 0.001) being the highest concentrations of calprotectin observed in serum samples. Deming regression equation was as follows: Diasorin calprotectin (μg/ml) = −0.32 (95% CI: −0.65 ‐ −0.05) +1.58 (95% CI: 1.42–1.79).* Calprolab calprotectin (μg/ml). Significantly higher serum calprotectin levels were found in RA patients with active disease when compared to patients with low disease activity or in clinical remission (mean ± SD) [(3.35 μg/ml ± 1.55) vs. (1.63 μg/ml ± 0.52), p < 0.001] and these levels correlated well with all disease activity indices.

Conclusions

The DiaSorin Liaison® fecal Calprotectin assay adapted for serum samples showed adequate technical performances and the clinical performances were similar to other assays.

Circulating calprotectin as biomarker in neutrophil-related inflammation: Pre-analytical recommendations and reference values according to sample type

BACKGROUND

Calprotectin (CLP) is a promising biomarker for the evaluation of neutrophil-related inflammation. Our aim was to establish reference values for circulating CLP in different sample types and to study the effect of pre-analytical variables.

METHODS

Reference values were determined in 100 healthy individuals. Pre-analytical variables were evaluated in 10 healthy controls and four rheumatoid arthritis patients with active disease and covered sample type (serum with/without gel separator, heparin, EDTA and citrate plasma), pre-centrifugation time (<2 h, 6 h, 24 h), storage condition (2-8 °C, 18-25 °C, 30 °C) and storage time (24 h, 72 h, 7 days). CLP measurements were performed with the EliA™Calprotectin 2 assay on Phadia™200 (Thermo Fisher Scientific).

RESULTS

In healthy controls, baseline CLP concentrations in serum were more than double the concentration in EDTA and citrate plasma (0.909 µg/mL versus 0.259 µg/mL and 0.261 µg/mL respectively). Heparin, EDTA and citrate stabilized CLP concentrations for up to 6 h before centrifugation, whereas significant increases in CLP levels were observed when serum was left untreated during that time period.

CONCLUSION

Clinical studies on circulating CLP need to apply sample type-specific reference values and decision limits. To obtain reproducible CLP results in serum, more stringent pre-analytical sample handling instructions are needed.

The Role of Calprotectin in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is an inflammatory autoimmune disease characterized by inflammatory cell infiltration, high levels of cytokines, and erosion of cartilage and bone in joints. Calprotectin (CLP), as a recently described member of S100 family proteins, is a heterodimeric complex of S100A8 and S100A9. Currently, plenty of studies have indicated significantly increased serum and synovial fluid levels of CLP in patients with RA. It was reported that CLP was related to cell differentiation, migration, apoptosis, and production of pro-inflammatory factors in RA. In addition, there are the positive relationships between serum, synovial CLP and traditional acute phase reactants, disease activity, ultrasound and radiographic progression of joints, and treatment response of RA. In this review, we mainly discuss the role of CLP in the pathogenesis of RA as well as its potential to estimate clinical disease progression of RA patients.

Calprotectin as a smoldering activity detection tool and renal prognosis biomarker in ANCA associated vasculitis

BACKGROUND

Calprotectin is produced by neutrophils and macrophages, and released during the acute phase of the ANCA vasculitis. The aim of our study was to determine if serum and urine calprotectin are disease activity and prognosis biomarkers in ANCA vasculitis patients during remission.

METHODS

Forty-two ANCA vasculitis patients were included. Twenty-seven patients were in remission phase under immunosuppressive therapy, and 15 patients were in the acute phase. Four healthy controls were included. We determined calprotectin in serum and urine samples at the time of the inclusion. We recorded the incidence of relapse and the evolution of GFR, proteinuria, hematuria, and C reactive protein and ANCA titer during 24 months of follow-up.

RESULTS

In remission phase, serum calprotectin was higher than in healthy controls but lower compared to acute patients (p = 0.05). Serum calprotectin at inclusion was higher in patients who increased proteinuria during follow-up (p = 0.04), with hematuria (p = 0.08), and with non-decreasing ANCA titer (p = 0.0019). Serum calprotectin at inclusion in stable patients who subsequently decreased GFR during follow-up was higher compared with those with a stable or improving GFR (p = 0.03). Urine calprotectin was lower in patients with sclerotic histology in remission (p = 0.03) and acute phase (p = 0.12) compared to the rest of histologies.

CONCLUSIONS

Worsening of renal function, hematuria, rising proteinuria and non-decreasing ANCA correlated with higher levels of serum calprotectin at recruitment. Low urine calprotectin was found in patients with sclerotic histology. Calprotectin during remission in ANCA vasculitis may be useful to identify subclinical inflammation and worse renal prognosis patients.

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 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.