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

Elevated NET, Calprotectin, and Neopterin Levels Discriminate between Disease Activity in COVID-19, as Evidenced by Need for Hospitalization among Patients in Northern Italy

Coronavirus disease 2019 (COVID-19) displays clinical heterogeneity, but little information is available for patients with mild or very early disease. We aimed to characterize biomarkers that are useful for discriminating the hospitalization risk in a COVID-19 cohort from Northern Italy during the first pandemic wave. We enrolled and followed for four weeks 76 symptomatic SARS-CoV-2 positive patients and age/sex-matched healthy controls. Patients with mild disease were discharged (n.42), and the remaining patients were hospitalized (n.34). Blood was collected before any anti-inflammatory/immunosuppressive therapy and assessed for soluble C5b-9/C5a, H3-neutrophil extracellular traps (NETs), calprotectin, and DNase plasma levels via ELISA and a panel of proinflammatory cytokines via ELLA. Calprotectin and NET levels discriminate between hospitalized and non-hospitalized patients, while DNase negatively correlates with NET levels; there are positive correlations between calprotectin and both NET and neopterin levels. Neopterin levels increase in patients at the beginning of the disease and do so more in hospitalized than non-hospitalized patients. C5a and sC5b-9, and other acute phase proteins, correlate with neopterin, calprotectin, and DNase. Both NET and neopterin levels negatively correlate with platelet count. We show that calprotectin, NETs, and neopterin are important proinflammatory parameters potentially useful for discriminating between COVID-19 patients at risk of hospitalization.

Neutrophils, neutrophil extracellular traps, and rheumatoid arthritis: An updated review for clinicians

Rheumatoid arthritis (RA) is a systemic autoimmune disease characterized by the presence of autoantibodies. Research on the pathogenic mechanisms involved in systemic autoimmune diseases has largely focused on the involvement of the adaptive immune system with dysregulated responses of T and B cells. However, in recent years, there is increasing evidence of the significant role played by the innate immune system, particularly neutrophils, in these diseases, particularly in RA. Neutrophil extracellular traps (NETs) are extracellular structures composed of remodeled and concentrated chromatin with DNA, histones, and neutrophil proteins, and were first described in 2004. It has been studied that NETs may play a pathogenic role in RA and could be a source of autoantigens, increasing the immune response in the form of autoantibodies in this disease. The possible role of NETs and other markers of neutrophil activation as biomarkers of activity in RA and other immune-mediated diseases has also been studied. This article reviews the role of NETs in RA. It discusses the role of neutrophils and the latest advances in NETs, especially their involvement in autoimmune phenomena in RA. Finally, a literature review is conducted on the determination of NETs in peripheral blood and their relationship as a biomarker of RA activity, as well as their potential role in disease monitoring.

Calprotectin, a sensitive marker of inflammation, is robustly assessed in plasma from patients with early or established rheumatoid arthritis by use of different laboratory methods

Calprotectin (S100A8/S100A9, MRP8/MRP14) is a major leukocyte protein found to be more sensitive than C-Reactive Protein (CRP) and Erythrocyte Sedimentation Rate (ESR) as a marker of inflammation in patients with rheumatoid arthritis (RA). The present objective was to explore the robustness of calprotectin assessments by comparing two different laboratory methods assessing calprotectin in plasma samples from patients with early or established RA. A total of 212 patients with early RA (mean (SD) age 52(13.3) years, disease duration 0.6(0.5) years) and 177 patients with established RA (mean (SD) age 52.9(13.0) years, disease duration 10.0(8.8) years) were assessed by clinical, laboratory, and ultrasound examinations. Frozen plasma samples (-80 °C) were analysed for calprotectin levels at baseline, 1, 2, 3, 6 and 12 months by use of either enzyme-linked immunosorbent assay (ELISA) or fluoroenzyme immunoassay (FEIA). The ELISA technique used kits from Calpro AS and the FEIA technology was assessed on an automated Thermo Fisher Scientific instrument. The results showed high correlations between the two methods at baseline and during follow-up, with Spearman correlation at baseline 0.93 (p < 0.001) in the early and 0.96 (p < 0.001) in the established RA cohorts. The correlations between each of the two calprotectin assessments and clinical examinations had similar range. Calprotectin correlated well with clinical examinations, with at least as high correlations as CRP and ESR. The present study showed similar results for the two analytical methods, supporting the robustness of calprotectin analyses, and suggest calprotectin in plasma to be included in the assessments offered by clinical routine laboratories.

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.

Characterization of serum biomarkers and antibody responses against Prevotella spp. in preclinical and new-onset phase of rheumatic diseases

Introduction

The characterization of the influence of the microbiota on the development and drug responses during rheumatic diseases has intensified in recent years. The role of specific bacteria during disease development has become a central research question. Notably, several lines of evidence point to distinct microbes, e.g., Prevotella copri (P. copri) being targeted by antibodies in clinical phases of rheumatic diseases.

Methods

In the present study, we compiled a broad collection of human serum samples from individuals at risk of developing RA, chronic RA patients as well as patients with new-onset of rheumatic diseases. We evaluated the presence of inflammatory biomarkers in our serum collection as well as serum antibody responses against novel, genetically distinct isolates of P. copri and several oral pathobionts.

Results

Our analysis revealed the presence of increased levels of inflammatory markers already in pre-clinical and new onset rheumatoid arthritis. However, antibody reactivity against the microbes did not differ between patient groups. Yet, we observed high variability between the different P. copri strains. We found total serum IgG levels to slightly correlate with IgG antibody responses against P. copri, but no relation between the latter and presence or prevalence of P. copri in the intestine.

Discussion

In conclusion, our work underlined the importance of strain-level characterization and its consideration during further investigations of host-microbiota interactions and the development of microbiome-based therapeutic approaches for treating rheumatic diseases.

Brief report: Assessment of mucosal barrier integrity using serological biomarkers in preclinical stages of rheumatoid arthritis

Background

The pathogenesis of rheumatoid arthritis (RA) is believed to initiate at mucosal sites. The so-called 'mucosal origin hypothesis of RA' postulates an increased intestinal permeability before disease onset. Several biomarkers, including lipopolysaccharide binding protein (LBP) and intestinal fatty acid binding protein (I-FABP), have been proposed to reflect gut mucosa permeability and integrity, while serum calprotectin is a new inflammation marker proposed in RA.

Methods

We analyzed serum samples of individuals genetically at increased risk of RA in a nested-case-control study. Participants from a longitudinal cohort of first-degree relatives of RA patients (SCREEN-RA cohort) were divided into three pre-clinical stages of RA, based on the presence of risk factors for subsequent RA onset: 1) low-risk healthy asymptomatic controls; 2) intermediate-risk individuals without symptoms, but with RA-associated auto-immunity; 3) high-risk individuals with clinically suspect arthralgias. Five patients with newly diagnosed RA were also sampled. Serum LBP, I-FABP and calprotectin were measured using commercially available ELISA kits.

Results

We included 180 individuals genetically at increased risk for RA: 84 asymptomatic controls, 53 individuals with RA-associated autoimmunity and 38 high risk individuals. Serum LBP, I-FAPB or calprotectin concentrations did not differ between individuals in different pre-clinical stages of RA.

Conclusion

Based on the serum biomarkers LBP, I-FABP and calprotectin, we could not detect any evidence for intestinal injury in pre-clinical stages of RA.

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.

Polymorphisms of Calgranulin Genes and Ischemic Stroke in a Chinese Population

Background

The S100/calgranulin gene appears to modulate neuroinflammation following cerebral ischemia and could be a valuable biomarker for stroke prognosis, according to growing research. This study aimed at evaluating the correlation between calgranulin gene variants and susceptibility to ischemic stroke (IS) in the Southern Chinese population.

Methods

Using an enhanced multi-temperature ligase detection reaction genotyping, 310 IS patients and 324 age-matched healthy controls were genotyped to identify five calgranulin gene variants.

Results

According to the obtained results, the S100A8 rs3795391, rs3806232, and S100A12 rs2916191 variants were linked to a higher risk of IS, while the S100A9 rs3014866 variant was associated with a lower risk of IS. Moreover, the T-T-C-A-T, T-T-C-G-T, or C-C-C-G-C haplotypes have been linked to a greater risk of developing IS, according to haplotype analysis. The occurrence of the variant C allele there in S100A8 rs3795391, rs3806232, and S100A12 rs2916191 variants may impart a greater risk of stroke in the LAA subtype, according to further stratification by IS subtypes, while the T allele of the S100A9 rs3014866 variant may be linked to a reduced risk of stroke of all subtypes. Furthermore, patients with the variant C allele of the S100A8 rs3795391, rs3806232, and S100A12 rs2916191 variants presented with increased circulating S100A8 and S100A12 levels and larger infarct volumes relative to those with the major TT genotype.

Conclusion

Our findings suggest that calgranulin gene variants are linked to IS susceptibility, implying that the calgranulin gene may be a potential biomarker for IS prevention and personalized treatment.

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.

A Cross-Sectional and Longitudinal Study to Define Alarmins and A-SAA Variants as Companion Markers in Early Rheumatoid Arthritis

Nowadays, in the study of rheumatoid arthritis (RA), more and more interest is directed towards an earlier effective therapeutic intervention and the determination of companion markers for predicting response to therapy with the goal to prevent progressive joint damage, deformities, and functional disability. With the present work, we aimed at quantifying in a cohort of early RA (ERA) patients naïve to DMARD therapy, proteins whose increase was previously found associated with RA: serum amyloid A (A-SAA) and alarmins. Five A-SAA variants (SAA1α, SAA1β, SAA1γ, SAA2α, and SAA2β) but also S100A8 and S100A9 proteins were simultaneously quantified in plasma applying a method based on single targeted bottom-up proteomics LC-MS/MS. First, we compared their expression between ERA (n = 100) and healthy subjects (n = 100), then we focused on their trend by monitoring ERA patients naïve to DMARD treatment, 1 year after starting therapy. Only SAA1α and SAA2α levels were increased in ERA patients, and SAA2α appears to mostly mediate the pathological role of A-SAA. Levels of these variants, together with SAA1β, only decreased under biologic DMARD treatment but not under methotrexate monotherapy. This study highlights the importance to better understand the modulation of expression of these variants in ERA in order to subsequently better characterize their biological function. On the other hand, alarmin expression increased in ERA compared to controls but remained elevated after 12 months of methotrexate or biologic treatment. The work overcomes the concept of considering these proteins as biomarkers for diagnosis, demonstrating that SAA1α, SAA1β, and SAA2α variants but also S100A8 and S100A9 do not respond to all early treatment in ERA and should be rather considered as companion markers useful to improve the follow-up of treatment response and remission state. Moreover, it suggests that earlier use of biologics in addition to methotrexate may be worth considering.

Interleukin-6 and Serum/Fecal Calprotectin as Useful Specific Markers for Monitoring Rheumatic Diseases: A Pilot Study

OBJECTIVE

Some conventional laboratory tests are routinely used for the prediction of systemic autoimmune disease activity, such as the erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP); however, they can give false-negative results, pointing out the need to identify more specific markers.

METHODS

We evaluated biomarkers in 21 Italian patients naïve to treatment with a diagnosis of autoimmune rheumatic disease according to the 2010 American College of Rheumatology/European League Against Rheumatism Classification Criteria for Rheumatoid Arthritis during 6 months of therapeutic treatments.

RESULTS

We found a significant difference in interleukin-6 (IL-6), CRP, ESR, platelet count, and fecal calprotectin in diagnosed patients compared with healthy participants and a significant decrease in these values during follow-up, except for IL-6 and platelet count.

CONCLUSION

We found that CRP, ESR, and fecal calprotectin seemed to be related to autoimmune rheumatic disorders and to be associated with therapy, whereas serum calprotectin and IL-6 did not seem to be associated with disease improvement after the start of treatment, along with leukocyte count and platelet count.

Increased hexokinase-2 as a novel biomarker for the diagnosis and correlating with disease severity in rheumatoid arthritis

Abnormal glucose metabolism brings out joint inflammation and destruction in rheumatoid arthritis (RA). The aim of this study was to evaluate the potential of circulating hexokinase-2 (HK2) in peripheral blood mononuclear cells (PBMCs) of rheumatoid arthritis (RA) patients.PBMCs were obtained from patients with RA or osteoarthritis (OA) and healthy controls (HCs). The expression of HK2 was assessed by quantitative reverse transcription-polymerase chain reaction (qRT-PCR). The C-reactive protein (CRP) level, erythrocyte sedimentation rate (ESR), Calprotectin, rheumatoid factor (RF), anti-cyclic citrullinated peptides (anti-CCP) antibody level and 28-joint Disease Activity Score (DAS28), Clinical Disease Activity Index (CDAI) and Simplified Disease Activity Index (SDAI) were measured. Spearman's analysis was performed to determine the association between the level of HK2 and clinical characteristics. A receiver operating characteristic (ROC) curve was employed to evaluate the diagnostic value of HK2 in PBMCs. Logistic regression was used to identify risk factors. Sixty-five RA patients, 35 OA patients, and 40 HCs were included in the study.HK2 was upregulated in RA and OA patients compared with that in HCs (P < .05). The area under the ROC of HK2 for diagnosing RA and OA was 0.808 and 0.640, respectively. In addition, HK2 levels were increased in active RA compared with those in remittent RA (P = .03). Furthermore, HK2 correlated positively with the DAS28-ESR (P < .001), CDAI (P = .02) and SDAI scores (P = .02). Moreover, HK2 was independently associated with an increased risk of disease activity (DAS28-ESR>3.2, P = .02; CDAI score>10, P = .03; SDAI score>11, P = .04). Additionally, HK2 positivity was more frequently detected in patients treated with biologic disease-modifying antirheumatic drugs (bDMARDs) than in those not treated with bDMARDs.HK2 levels in PBMCs can be considered an ideal biomarker for diagnosing RA and involved in disease activity in RA. Dysregulation of HK2 may participate in the molecular mechanism of RA and could be an attractive selective metabolic target for RA treatment.

Fisetin inhibits inflammation and induces autophagy by mediating PI3K/AKT/mTOR signaling in LPS-induced RAW264.7 cells

Background

Fisetin, a natural potent flavonoid, has various beneficial, pharmacological activities. In this study, we investigated expression changes of the fisetin regulating genes in lipopolysaccharide (LPS)-treated RAW264.7 cells and explored the role of fisetin in inflammation and autophagy.

Methods and results

Microarray analysis identified 1,071 genes that were regulated by fisetin in LPS-treated RAW264.7 cells, and these genes were mainly related to the process of immune system response. Quantitative real-time polymerase chain reaction and Bio-Plex analysis indicated that fisetin decreased the expression and secretion of several inflammatory cytokines in cells administered with LPS. Western blot analysis and immunofluorescence assay showed that fisetin decreased microtubule-associated protein 1 light-chain 3B (LC3B) and lysosome-associated membrane protein 1 (LAMP1) expression in LPS-treated cells, while the autophagy inhibitor chloroquine (CQ) could partially reverse this effect. In addition, fisetin reduced the elevated expression of p-PI3K, p-AKT and p-mTOR induced by LPS in a concentration-dependent manner.

Conclusions

Fisetin diminished the expression and secretion of inflammatory cytokines and facilitated autophagosome-lysosome fusion and degradation in LPS-treated RAW264.7 cells via inhibition of the PI3K/AKT/mTOR signaling pathway. Overall, the results of this study provide new clues for the anti-inflammatory mechanism of fisetin and explain the crosstalk between autophagy and inflammation to some extent.

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.

Serum Calprotectin is Indicating Clinical and Ultrasonographic Disease Activity in Rheumatoid Arthritis, even with Normal C-Reactive Protein Levels

Objective:

Calprotectin is an inflammatory biomarker which assesses disease activity in rheumatoid arthritis (RA). The objective of this study was to test whether serum calprotectin is associated with clinical and ultrasonographic disease activity in patients with RA, and to analyse its predicting value for disease activity evaluation despite normal C-Reactive protein (CRP) levels.

Methods:

We included 80 patients with RA and 30 healthy subjects. Patients were examined clinically and by ultrasound, (US7 score) along with laboratory parameters (calprotectin, CRP, erythrocyte sedimentation rate [ESR]). Disease activity scores (DAS28) were calculated to assess disease activity. Firstly, patients were divided into four subgroups according to the DAS28-ESR (high, moderate, low disease activity, and remission), then into two subgroups; group-1 (DAS-28≤3.2) and group-2 (DAS28>3.2). The predicting value of calprotectin for disease activity in patients with normal CRP was analysed with univariate and multivariate analysis and receiver operating characteristic curves.

Results:

Calprotectin levels were higher in RA patients than controls (96.3±45.9 ng/ml, 54.7±50.0 ng/ml, respectively; p<0.001). Calprotectin levels were 74.8±45.5 ng/ml in group-1 (n=37) and 114.7±37.9 ng/ml in group-2 (n=43) (p<0.001). In univariate analyses, calprotectin was significantly correlated with clinical, laboratory, and ultrasound parameters (p<0.05), and was a better predictor of power doppler synovitis than CRP in multivariate analysis (OR=1.014; 95%CI 1.002–1.027; p=0.024). The discriminatory capacity for calprotectin to distinguish ultrasonographically active disease in patients with normal CRP levels using AUC was 0.75 (95%CI 0.56–0.90, p=0.023).

Conclusions:

Calprotectin represents disease activity, even in patients who are clinical and ultrasonographical active but have normal CRP levels.

Comparable long-term outcomes between DAS28-ESR remission criteria and ACR/EULAR definitions in patients with established rheumatoid arthritis

OBJECTIVE

To compare long-term clinical, immunological, and radiographic outcomes between five sets of remission criteria (four clinical and one ultrasound (US)-based) in a cohort of RA patients in a clinical care setting.

METHODS

RA patients in remission (DAS28-ESR <2.6) were selected. Hand US assessments were made, and serum levels of inflammation/angiogenesis biomarkers were determined at baseline. Changes in baseline treatment and radiographic progression, defined as the variation in the modified Sharp van der Heijde score (mSHS) at 5 years, were analyzed. Five concepts were used to define remission: DAS28-ESR<2.6, SDAI<3.3, CDAI<2.8, Boolean criteria and Power Doppler score (PD)=0.

RESULTS

Eighty-seven patients with DAS28-ESR<2.6 were included. One-third fulfilled SDAI (33.3%), CDAI (31%), and Boolean (35.6%) remission criteria, and 25.3% had no PD signal in the US evaluation. 26 patients (29.9%) changed therapy, ranging from 13.6% (PD remission) to 33.3% (CDAI remission) (p=0.11). Serum levels of ANG (p=0.015) and TNFa (p=0.025) were significantly lower in patients with Boolean remission, whereas IL-18 levels were significantly lower in those with PD remission (p=0.049). Patients without PD in the US assessment had significantly-lower mSHS erosion progression (p=0.014) at 5 years.

CONCLUSIONS

Patients with established RA in DAS28-ESR remission had comparable clinical and radiographic outcomes in SDAI, CDAI, and Boolean definitions in a clinical care setting. US remission remained the closest to structural damage abrogation. Key Points • This study provides real world data on long-term outcomes of five clinical and imaging remission criteria in rheumatoid arthritis. • DAS28-ESR remission criteria had comparable radiographic progression and clinical prognosis than more stringent criteria in clinical practice. • US-based remission was closest to structural damage abolishment.

Three hematologic/immune system-specific expressed genes are considered as the potential biomarkers for the diagnosis of early rheumatoid arthritis through bioinformatics analysis

BACKGROUND

Rheumatoid arthritis (RA) is the most common chronic autoimmune connective tissue disease. However, early RA is difficult to diagnose due to the lack of effective biomarkers. This study aimed to identify new biomarkers and mechanisms for RA disease progression at the transcriptome level through a combination of microarray and bioinformatics analyses.

METHODS

Microarray datasets for synovial tissue in RA or osteoarthritis (OA) were downloaded from the Gene Expression Omnibus (GEO) database, and differentially expressed genes (DEGs) were identified by R software. Tissue/organ-specific genes were recognized by BioGPS. Enrichment analyses were performed and protein-protein interaction (PPI) networks were constructed to understand the functions and enriched pathways of DEGs and to identify hub genes. Cytoscape was used to construct the co-expressed network and competitive endogenous RNA (ceRNA) networks. Biomarkers with high diagnostic value for the early diagnosis of RA were validated by GEO datasets. The ggpubr package was used to perform statistical analyses with Student's t-test.

RESULTS

A total of 275 DEGs were identified between 16 RA samples and 10 OA samples from the datasets GSE77298 and GSE82107. Among these DEGs, 71 tissue/organ-specific expressed genes were recognized. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis indicated that DEGs are mostly enriched in immune response, immune-related biological process, immune system, and cytokine signal pathways. Fifteen hub genes and gene cluster modules were identified by Cytoscape. Eight haematologic/immune system-specific expressed hub genes were verified by GEO datasets. GZMA, PRC1, and TTK may be potential biomarkers for diagnosis of early RA. NEAT1-miR-212-3p/miR-132-3p/miR-129-5p-TTK, XIST-miR-25-3p/miR-129-5p-GZMA, and TTK_hsa_circ_0077158- miR-212-3p/miR-132-3p/miR-129-5p-TTK might be potential RNA regulatory pathways to regulate the disease progression of early RA.

CONCLUSIONS

This work identified three haematologic/immune system-specific expressed genes, namely, GZMA, PRC1, and TTK, as potential biomarkers for the early diagnosis and treatment of RA and provided insight into the mechanisms of disease development in RA at the transcriptome level. In addition, we proposed that NEAT1-miR-212-3p/miR-132-3p/miR-129-5p-TTK, XIST-miR-25-3p/miR-129-5p-GZMA, and TTK_hsa_circ_0077158-miR-212-3p/miR-132-3p/miR-129-5p-TTK are potential RNA regulatory pathways that control disease progression in early RA.

Association of calprotectin with other inflammatory parameters in the prediction of mortality for ischemic stroke

BACKGROUND

Inflammatory response plays an important role in many processes related to acute ischemic stroke (AIS). Calprotectin (S100A8/S100A9), released by monocytes and neutrophils, is a key protein in the regulation of inflammation and thrombosis. The purpose of this study is to evaluate the association of circulating calprotectin with other inflammatory biomarkers and AIS prognosis, as well as the calprotectin content in stroke thrombi.

METHODS

Among the 748 patients treated at a comprehensive stroke center between 2015 and 2017, 413 patients with confirmed acute ischemic injury were prospectively evaluated. Patients with systemic inflammation or infection at onset were excluded. Plasma calprotectin was measured by ELISA in blood samples of AIS patients within the first 24 h. Univariate and multivariate logistic regression models were performed to evaluate its association with mortality and functional independence (FI) at 3 months (defined as modified Rankin Scale < 3) and hemorrhagic transformation (HT) after ischemic stroke. Further, S100A9 was localized by immunostaining in stroke thrombi (n = 44).

RESULTS

Higher calprotectin levels were associated with 3-month mortality, HT, and lower 3-month FI. After adjusting for potential confounders, plasma calprotectin remained associated with 3-month mortality [OR (95% CI) 2.31 (1.13-4.73)]. Patients with calprotectin ≥ 2.26 μg/mL were 4 times more likely to die [OR 4.34 (1.95-9.67)]. Addition of calprotectin to clinical variables led to significant improvement in the discrimination capacity of the model [0.91 (0.87-0.95) vs 0.89 (0.85-0.93); p < 0.05]. A multimarker approach demonstrated that patients with increased calprotectin, CRP, and NLR had the poorest outcome with a mortality rate of 42.3% during follow-up. S100A9 protein, as part of the heterodimer calprotectin, was present in all thrombi retrieved from AIS patients. Mean S100A9 content was 3.5% and tended to be higher in patients who died (p = 0.09). Moreover, it positively correlated with platelets (Pearson r 0.46, p < 0.002), leukocytes (0.45, p < 0.01), and neutrophil elastase (0.70, p < 0.001) thrombus content.

CONCLUSIONS

Plasma calprotectin is an independent predictor of 3-month mortality and provides complementary prognostic information to identify patients with poor outcome after AIS. The presence of S100A9 in stroke thrombi suggests a possible inflammatory mechanism in clot formation, and further studies are needed to determine its influence in resistance to reperfusion.

Plasma calprotectin as a biomarker of mortality at antiretroviral treatment initiation in advanced HIV - pilot study

Background: In advanced HIV, significant mortality occurs soon after starting antiretroviral treatment (ART) in low- and middle-incomes countries. Calprotectin is a biomarker of innate response to infection and inflammatory conditions. We examined the association between plasma calprotectin collected before ART treatment and mortality among individuals with advanced HIV.   Methods: We conducted a pilot case-cohort study among HIV infected adults and adolescents over 13 years old with CD4+ <100/mm3 at ART initiation at two Kenyan sites. Participants received three factorial randomised interventions in addition to ART within the REALITY trial (ISRCTN43622374). Calprotectin collected at baseline (before ART) and after 4 weeks of treatment was measured in archived plasma of those who died within 24 weeks (cases) and randomly selected participants who survived (non-cases). Association with mortality was assessed using Cox proportional hazards models with inverse sampling probability weights and adjusted for age, sex, site, BMI, viral load, randomised treatments, and clustered by CD4+ count (0-24, 25-49, and 50-99 cells/mm3).   Results: Baseline median (IQR) plasma calprotectin was 6.82 (2.65-12.5) µg/ml in cases (n=39) and 5.01 (1.92-11.5) µg/ml in non-cases (n=58). Baseline calprotectin was associated with age, neutrophil count and the presence of cough, but not other measured indicators of infection. In adjusted multivariable models, baseline calprotectin was associated with subsequent mortality: HR 1.64 (95% CI 1.11 - 2.42) and HR 2.77 (95% CI 1.58 - 4.88) for deaths during the first twenty-four and four weeks respectively. Calprotectin levels fell between baseline and 4 weeks among both cases and non-cases irrespective of randomised interventions.   Conclusions: Among individuals with advanced HIV starting ART in Kenya, plasma calprotectin may have potential as a biomarker of early mortality. Validation in larger studies, comparison with other biomarkers and investigation of the sources of infection and inflammation are warranted.

Contribution of Multiplex Immunoassays to Rheumatoid Arthritis Management: From Biomarker Discovery to Personalized Medicine

Rheumatoid arthritis (RA) is a multifactorial, inflammatory and progressive autoimmune disease that affects approximately 1% of the population worldwide. RA primarily involves the joints and causes local inflammation and cartilage destruction. Immediate and effective therapies are crucial to control inflammation and prevent deterioration, functional disability and unfavourable progression in RA patients. Thus, early diagnosis is critical to prevent joint damage and physical disability, increasing the chance of achieving remission. A large number of biomarkers have been investigated in RA, although only a few have made it through the discovery and validation phases and reached the clinic. The single biomarker approach mostly used in clinical laboratories is not sufficiently accurate due to its low sensitivity and specificity. Multiplex immunoassays could provide a more complete picture of the disease and the pathways involved. In this review, we discuss the latest proposed protein biomarkers and the advantages of using protein panels for the clinical management of RA. Simultaneous analysis of multiple proteins could yield biomarker signatures of RA subtypes to enable patients to benefit from personalized medicine.

Fatigue is cross-sectionally not associated with objective assessments of inflammation, but changes in fatigue are associated with changes of disease activity assessments during biologic treatment of patients with established rheumatoid arthritis

Objective

The associations between fatigue and disease activity in patients with rheumatoid arthritis (RA) have not been defined. The present objectives were to explore in RA patients the cross-sectional and longitudinal relation of fatigue with subjective as well as objective assessments of disease activity.

Methods

RA patients were consecutively included when initiating biologic disease-modifying anti-rheumatic drugs (DMARDs) and assessed at baseline, 1, 2, 3, 6, and 12 months with investigation of fatigue, patient-reported outcome measures (PROMs; joint pain and patient’s global disease activity, MHAQ, pain catastrophizing, Mental Health score), clinical examinations (examiner’s global disease activity, 28 tender and swollen joint counts), and laboratory variables (ESR, CRP, calprotectin). Ultrasound examinations (semi-quantitative scoring (0–3)) with grey scale and power Doppler were performed of 36 joints and 4 tendons. Statistics included one-way analysis of variance, Pearson’s correlations, and multiple linear and logistic regression analysis.

Results

A total of 208 RA patients (mean (SD) age 53.2 (13.2) years, disease duration 9.8 (8.5) years) were included. Fatigue levels diminished during follow-up (mean (SD) baseline/12 months; 4.8 (2.8)/3.0 (2.5) (p < 0.001)). Substantial correlations were cross-sectionally found between fatigue and PROMs (median (IQR) r=0.61 (0.52-0.71)) but not with the objective inflammatory assessments. During follow-up, baseline fatigue was associated with PROMs (p < 0.001) but not with objective inflammatory assessments. However, change of fatigue was associated with change in all variables. Higher baseline fatigue levels were associated with lower clinical composite score remission rates.

Conclusion

Fatigue was cross-sectionally associated to subjective but not to objective disease assessments. However, change of fatigue during treatment was associated to all assessments of disease activity.

Trial registration number

Anzctr.org.au identifier ACTRN12610000284066, Norwegian Regional Committee for Medical and Health Research Ethics South East reference number 2009/1254

Key Points • In this longitudinal study of patients with established RA, fatigue was associated with patient reported outcome measures at each visit, but not with objective assessments of inflammation including calprotectin and comprehensive ultrasound examinations. • Changes in fatigue during biological treatment were associated with changes in patient reported outcome measures, clinical, laboratory and ultrasound assessments. • Baseline fatigue was associated with all patient reported outcome measures, but not objective assessments of inflammation at all the prospective visits. • Higher baseline fatigue levels were associated with lower remission rates as assessed by clinical composite scores.

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.

Calprotectin in spondyloarthritis: A systematic review and meta-analysis

OBJECTIVE

There is still an unmet need for a simple and reliable biomarker for diagnosis and disease activity of spondyloarthritis. Recent studies indicated that calprotectin could act as a biomarker for spondyloarthritis. Therefore, this systematic review and meta-analysis aims to evaluate the levels of serum and fecal calprotectin in spondyloarthritis and the associations with disease activity.

METHODS

PubMed, Web of Science and Cochrane Library were comprehensively searched from inception to July 1st, 2019. The pooled standard mean differences (SMDs) were used to estimate the differences of the levels of serum and fecal calprotectin between spondyloarthritis patients and controls. Spearman correlation coefficients were used for evaluating the associations between the levels of serum and fecal calprotectin and disease activity of spondyloarthritis patients. The use of fixed-effect or random-effects model depended on heterogeneity.

RESULTS

Among 257 searched studies, 20 studies were finally included for analysis. Serum and fecal calprotectin were both significantly increased in spondyloarthritis patients compared to matched controls (SMD = 1.49, 95% CI = 0.91 to 2.08; SMD = 2.29, 95% CI = 0.25 to 4.33). The pooled correlation coefficients between serum or fecal calprotectin and CRP, ESR, BASDAI and BASFI were 0.353, 0.228, 0.225, 0.131 and 0.185, 0.163, 0.280, 0.196 respectively.

CONCLUSION

Our study indicated that serum and fecal calprotectin were significantly increased in spondyloarthritis patients, and associated with disease activity. Serum and fecal calprotectin were potential biomarkers for the diagnosis and disease activity of spondyloarthritis.

Maternal diet during pregnancy and intestinal markers are associated with early gut microbiota

BACKGROUND

Diet has an important role in host-microbiome interplay, which may result in intestinal permeability changes and physiopathological effects at a systemic level. Despite the importance of maternal microbiota as the main contributor to the initial microbial seeding, little is known about the effects of maternal diet during pregnancy on maternal-neonatal microbiota.

OBJECTIVES

This study aimed at ascertaining the possible associations between maternal dietary intake during pregnancy and neonatal microbiota at birth and to evaluate the relationship with maternal intestinal markers.

METHODS

In a nested cross-sectional study in the longitudinal MAMI cohort, maternal-neonatal microbiota profiling at birth (n = 73) was assessed by 16S rRNA gene sequencing. Maternal intestinal markers as zonulin, intestinal alkaline phosphatase (IAP) activity and faecal calprotectin were measured in faeces. Furthermore, maternal-neonatal clinical and anthropometric data, as well as maternal nutrient intake during pregnancy obtained by FFQ questionnaires, were collected.

RESULTS

Maternal diet is associated with both maternal and neonatal microbiota at the time of birth, in a delivery mode-dependent manner. The existing link between maternal diet, intestinal makers and neonatal gut microbiota would be mainly influenced by the intake of saturated (SFA) and monounsaturated fatty acids (MUFA). Members of Firmicutes in the neonatal microbiota were positively associated with maternal fat intake, especially SFA and MUFA, and negatively correlated to fibre, proteins from vegetable sources and vitamins.

CONCLUSIONS

Maternal diet during pregnancy, mainly fat intake (SFA and MUFA), was related to intestinal markers, thus likely shifting the microbial transmission to the neonate and priming the neonatal microbial profile with potential health outcomes.

CLINICAL TRIAL REGISTRY

NCT03552939.

Expression of S100A Alarmins in Cord Blood Monocytes Is Highly Associated With Chorioamnionitis and Fetal Inflammation in Preterm Infants

Background: Preterm infants exposed to chorioamnionitis and with a fetal inflammatory response are at risk for neonatal morbidity and adverse outcome. Alarmins S100A8, S100A9, and S100A12 are expressed by myeloid cells and have been associated with inflammatory activation and monocyte modulation.

Aim: To study S100A alarmin expression in cord blood monocytes from term healthy and preterm infants and relate results to clinical findings, inflammatory biomarkers and alarmin protein levels, as well as pathways identified by differentially regulated monocyte genes.

Methods: Cord blood CD14+ monocytes were isolated from healthy term (n = 10) and preterm infants (<30 weeks gestational age, n = 33) by MACS technology. Monocyte RNA was sequenced and gene expression was analyzed by Principal Component Analysis and hierarchical clustering. Pathways were identified by Ingenuity Pathway Analysis. Inflammatory proteins were measured by Multiplex ELISA, and plasma S100A proteins by mass spectrometry. Histological chorioamnionitis (HCA) and fetal inflammatory response syndrome (FIRS) were diagnosed by placenta histological examination.

Results: S100A8, S100A9, and S100A12 gene expression was significantly increased and with a wider range in preterm vs. term infants. High S100A8 and S100A9 gene expression (n = 17) within the preterm group was strongly associated with spontaneous onset of delivery, HCA, FIRS and elevated inflammatory proteins in cord blood, while low expression (n = 16) was associated with impaired fetal growth and physician-initiated delivery. S100A8 and S100A9 protein levels were significantly lower in preterm vs. term infants, but within the preterm group high S100A gene expression, spontaneous onset of labor, HCA and FIRS were associated with elevated protein levels. One thousand nine hundred genes were differentially expressed in preterm infants with high vs. low S100A alarmin expression. Analysis of 124 genes differentially expressed in S100A high as well as FIRS and HCA groups identified 18 common pathways and S100A alarmins represented major hubs in network analyses.

Conclusion: High expression of S100A alarmins in cord blood monocytes identifies a distinct clinical risk group of preterm infants exposed to chorioamnionitis and with a fetal inflammatory response. Gene and pathway analyses suggest that high S100A alarmin expression also affects monocyte function. The connection with monocyte phenotype and inflammation-stimulated S100A expression in other cell types (e.g., neutrophils) warrants further investigation.

Serum calprotectin: a promising biomarker in rheumatoid arthritis and axial spondyloarthritis

Background

Calprotectin (S100A8/S100A9 protein) is known as a damage-associated molecular pattern (DAMP) protein and reflects mainly neutrophil activation. Serum calprotectin levels might be a good alternative to acute-phase protein as a biomarker in inflammatory rheumatic diseases. The aim of this study is to investigate the association of serum calprotectin with disease activity and severity in rheumatoid arthritis (RA), axial spondyloarthritis (axSpA), and psoriatic arthritis (PsA).

Methods

Serum calprotectin was measured in patients with RA, axSpA, and PsA from the prospective Swiss Clinical Quality Management (SCQM) registry. Asymptomatic first-degree relatives of RA patients were used as healthy controls (HC). Outcomes included swollen joint count (SJC), Disease Activity Score (DAS), Health Assessment questionnaire (HAQ), joint radiographs, and ultrasound power Doppler (USPD) score for RA; Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Ankylosing Spondylitis Disease Activity Score (ASDAS) and coxitis for axSpA; and SJC and Disease Activity Index for PSoriatic Arthritis (DAPSA) for PsA. Comparison of outcomes by calprotectin quartile levels was performed using Kruskal-Wallis tests for continuous outcomes or trend tests for categorical outcomes.

Results

A total of 1729 subjects [RA = 969, axSpA = 451, PsA = 237, and HC = 72] were included. Median levels of serum calprotectin were higher in each disease group compared to HC (p < 0.01). In RA patients, all clinical outcomes were statistically different between quartiles of serum calprotectin, indicating an association between calprotectin levels and higher disease activity (SJC, DAS, and USPD scores) and severity (joint radiographs and HAQ). In axSpA, an association between calprotectin levels and ASDAS score (p < 0.01) and prevalence of coxitis (p = 0.02) was observed. For PsA patients, SJC and DAPSA did not differ across calprotectin quartiles.

Conclusions

This large study supports the association of serum calprotectin levels with disease activity in both RA and axSpA, but not in PsA.

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.

Fc-gamma receptors and S100A8/A9 cause bone erosion during rheumatoid arthritis. Do they act as partners in crime?

Bone erosion is one of the central hallmarks of RA and is caused by excessive differentiation and activation of osteoclasts. Presence of autoantibodies in seropositive arthritis is associated with radiographic disease progression. ICs, formed by autoantibodies and their antigens, activate Fcγ-receptor signalling in immune cells, and as such stimulate inflammation-mediated bone erosion. Interestingly, ICs can also directly activate osteoclasts by binding to FcγRs on their surface. Next to autoantibodies, high levels of alarmins, among which is S100A8/A9, are typical for RA and they can further activate the immune system but also directly promote osteoclast function. Therefore, IC-activated FcγRs and S100A8/A9 might act as partners in crime to stimulate inflammation and osteoclasts differentiation and function, thereby stimulating bone erosion. This review discusses the separate roles of ICs, FcγRs and alarmins in bone erosion and sheds new light on the possible interplay between them, which could fuel bone erosion.

Plasma calprotectin as a biomarker of mortality at antiretroviral treatment initiation in advanced HIV - pilot study

Background: In advanced HIV, significant mortality occurs soon after starting antiretroviral treatment (ART) in low- and middle-incomes countries. Calprotectin is a biomarker of innate response to infection and inflammatory conditions. We examined the association between plasma calprotectin at initiation of ART and mortality among individuals with advanced HIV. Methods: We conducted a pilot case-cohort study among HIV infected adults and children over 5 years old with CD4 + <100/mm 3 at ART initiation at two Kenyan sites. Participants received three factorial randomised interventions in addition to ART within the REALITY trial ( ISRCTN43622374). Calprotectin was measured by ELISA in archived plasma of those who died within 24 weeks (cases) and randomly selected participants who survived for 48 weeks (non-cases) for whom samples were available. Factors associated with baseline plasma calprotectin were investigated using linear regression. To test association with mortality, Cox proportional hazards models with inverse sampling probability weights and adjusted for age, sex, site, BMI, viral load, randomised treatments, and clustered by CD4 count were fitted. Results: Baseline median (IQR) plasma calprotectin was 6.82 (2.65-12.5) µg/ml in cases (n=39) and 5.01 (1.92-11.5) µg/ml in non-cases (n=58). Baseline calprotectin was associated with age, neutrophil count and the presence of cough, but not other measured indicators of infection. In adjusted multivariable models, baseline calprotectin was associated with subsequent mortality: HR 1.64 (95% CI 1.11 - 2.42) and HR 2.77 (95% CI 1.58 - 4.88) for deaths during the first twenty-four and four weeks respectively. Calprotectin levels fell between baseline and 4 weeks among both cases and non-cases irrespective of randomised interventions. Conclusion: Among individuals with advanced HIV starting ART in Kenya, plasma calprotectin may have potential as a biomarker of early mortality. Validation in larger studies, comparison with other biomarkers and investigation of the sources of infection and inflammation are warranted.

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.

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.

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.