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.

AB1338 CALPROTECTIN, A SENSITIVE MARKER OF INFLAMMATION, IS ROBUSTLY ASSESSED IN PLASMA FROM PATIENTS WITH ESTABLISHED RA BY USE OF DIFFERENT LABORATORY METHODS

Background

Calprotectin (S100A8/S100A9, MRP8/MRP14) in plasma has been shown to be more sensitive than C-Reactive Protein (CRP) or Erythrocyte Sedimentation Rate (ESR) in reflecting inflammatory activity in patients with rheumatoid arthritis (RA).1,2

Objectives

The present objective was to explore the robustness of laboratory examination of calprotectin by comparing the results from assessments by use of two different methods.

Methods

Frozen plasma samples from a study of 177 patients with established RA initiating biologic disease modifying drugs were analysed for calprotectin levels at baseline and after 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 (Oslo, Norway) and the samples were assessed in a semi-automatic analysis machine Dynex DS2 (Dynex Technologies, Virginia, USA) at Diakonhjemmet hospital. The Calpro AS kits included all necessary buffers, cleansing solutions, enzyme substrate, standards, and controls (high and low calprotectin levels) and their protocol was used for the calprotectin assessments. The standards and controls were used as the mean of two measures, while all the patient samples were analysed as single measures.

As a sub-study in NORA (a study exploring personalized medicine in RA by including several study cohorts from the Nordic countries), the same plasma samples were additionally assessed by FEIA. The FEIA technology used the EliATM calprotectin 2 wells in a Research Use Only setting on the PhadiaTM 2500 instrument (Phadia AB, Uppsala, Sweden) with a 1:50 dilution.

Spearman was used for correlation assessments. To explore differences across concentration levels the baseline calprotectin levels were divided into 3 groups based on results from the Calpro AS assay (normal levels; ≤ 910 µg/L; moderately elevated; 911-2000 µg/L, highly elevated; > 2000 µg/L).

Results

A total of 917 samples from the 177 patients (mean (SD) age 52.9 (13) years, disease duration 10 years (ranging from a few months to 46 years), 81% women, 78% anti-CCP IgG positive and 81% RF IgM positive) were included. The median of the correlation coefficients between the two methods at the six visits was 0.96 (range 0.91-0.97). Correlations were very high for normal levels (0.91) but somewhat lower for moderate and highly elevated levels (0.85 and 0.79, respectively). There were no significant differences between the associations depending on age, sex, or disease duration, nor on the anti-CCP IgG and RF IgM status of the patient.

Conclusion

The present study supports the robustness of calprotectin analyses, showing similar results across two different analytical methods, and that the concentrations were not influenced by demographic or immunological variables. Being a robust and more sensitive marker of inflammation than the commonly used CRP and ESR, calprotectin analyses should be available for assessments of RA patients in routine clinical care.

References

[1]Hammer, H.B., et al., Calprotectin (a major leucocyte protein) is strongly and independently correlated with joint inflammation and damage in rheumatoid arthritis. Ann Rheum Dis, 2007. 66(8): p. 1093-7.

[2]Hilde Haugedal Nordal HH et al. 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 Arthritis Research & Therapy (2017) 19:3

Disclosure of Interests

Hilde Berner Hammer Speakers bureau: AbbVie, Lilly and Novartis, Sigve Lans Pedersen: None declared, Isabel Gehring: None declared, Linda Mathsson-Alm: None declared, Joe Sexton: None declared, Johan Askling Grant/research support from: AbbVie, AstraZeneca, Bristol Myers Squibb, Eli Lilly, Janssen, Merck, Pfizer, Roche, Samsung Bioepis, Sanofi, and UCB

AB0122 THE NORA PROJECT - PREDICTION OF THERAPY RESPONSE IN RHEUMATOID ARTHRITIS

Background:

Personalized medicine in Rheumatoid arthritis (RA) especially regarding therapy response is still in early stages. The Nordic RA (NORA) project is aiming to improve the prediction of therapy outcome by combining established serologic marker with new markers, genetic information and patient-derived data.

Objectives:

As an initial step in the project the aim was to select clinically characterized patient cohorts and evaluate if changes or patterns in serological markers could predict therapy response and/or disease progress.

Methods:

The ARCTIC (Aiming for Remission in rheumatoid arthritis: a randomised trial examining the benefit of ultrasound in a Clinical TIght Control regimen) study [1] was designed to compare two tight control treatment strategies for early Rheumatoid arthritis and was used as a first cohort. Plasma samples (n=1622) from 224 RA patients from the ARCTIC study were included and taken at baseline and 3, 4, 6, 8, 10, 12, 14, 16, 20, and 24 months from trial start, and analyzed for the presence of EliATM RF (IgM, IgA, IgG), anti-CCP (IgG, IgA) and anti-RA33 (IgM, IgA, IgG) autoantibodies, as well as Calprotectin using the EliA instrument platform (Phadia AB, Uppsala, Sweden). In addition, a custom-made multiplex chip (Thermo Fisher Scientific, Sweden) [2] was used for measurement of anti-IgG antibodies against RA-specific antigens (citrullinated, acetylated and carbamylated), and established CTD-markers (Connective Tissue Disease), e.g. Ro52/60 and dsDNA. The citrullinated peptides on the multiplex chip were both multiple as well as single citrullinated at different positions within the peptide sequence. Additionally, we included an ELISA to measure antibodies against native human collagen II [3].

Results:

The different single assays in the baseline samples varied between 7 – 80% positive test results, e.g. anti-CCP IgG 80%. For some patients we could see changes in levels for anti-CCP, RF and anti-RA33 in the follow up samples, which varied from negative to more than 3-10xULN (Upper Limit of Normal). For anti-CCP IgG we found 9 patients (4%), who changed from negative to positive (patient 1-5) or from positive to negative (patient 6-8), while patient 9 had a peak at visit 6 (=12 months) and declined afterwards (figure 1). In addition, the above mentioned 9 patients showed clear changes in signal strength for the markers included on the multiplex chip and followed a similar pattern as the anti-CCP IgG signal. Different antibody patterns against single citrullinated peptides were observed and number of ACPA-positive peptides correlated with IgG anti-CCP levels.

Figure 1.

Anti-CCP IgG value normalised to cutoff (blue line) for patient 1 to 9. The heatmap visualizes the change over time in anti-CCP IgG signal with dark blue showing negative results and orange/red showing results >5xULN.

Anti-Collagen II antibodies (anti-CII) were detected in 15% of the baseline samples and in most cases declined over time. Two patients showed low baseline anti-CII levels that increased in the follow up samples. The changes in serological markers and the different reactivity patterns could possibly correlate with clinical outcome and define subgroups of patients with different response to therapy.

Results could be repeated in RA patients from the NOR-VEAC [4] cohort. At baseline 73% of the 106 RA patients had a positive anti-CCP IgG result and 11 patients (10%) showed a significant change of anti-CCP IgG level over time.

Conclusion:

Different response patterns and changes in serological antibody levels over the first 24 months after RA diagnosis could possibly reveal subgroups of patients with different prognosis and response to treatment. Further evaluations in additional treatment cohorts and correlation with clinical data are ongoing.

References:

[1]Haavardsholm et al., BMJ 2016;354:i4205.

[2]Hansson et al. Arthritis Research & Therapy 2012, 14:R201.

[3]Manivel et al Ann Rheum Dis. 2017 Sep;76(9):1529-1536.

[4]Mjaavatten et al., Arthritis Research & Therapy 2009, 11:R146.

Acknowledgements:

The NORA project is a NordForsk funded project.

Disclosure of Interests:

Linda Mathsson-Alm Employee of: Employee of Thermo Fisher Scientific, Isabel Gehring Employee of: Employee of Thermo Fisher Scientific, Maryam Poorafshar Employee of: Employee of Thermo Fisher Scientific, Johan Rönnelid: None declared, Johan Askling Grant/research support from: Research grants from Abbvie, Astra-Zeneca, BMS, Eli Lilly, MSD, Pfizer, Roche, Samsung Bioepis, Sanofi, and UCB, mainly in the context of safety monitoring (ARTIS), Espen Haavardsholm: None declared, Hilde Berner Hammer: None declared

FRI0040 MULTI-VARIATE APPROACH INCLUDING SEROLOGY AND GENETICS FOR AN IMPROVED IDENTIFICATION OF PATIENTS AT RISK OF DEVELOPING RA

Background:

First-degree relatives of rheumatoid arthritis (RA) patients (FDR-RA) have a 3 - 5-fold increased prevalence of the disease [1]. RA development is triggered by an interaction between genetic and environmental factors.

As the field is moving towards prevention in pre-clinical stages of RA, it is key to identify individuals with imminent RA, prior to onset of symptoms, which will presumably rely on both the measurement of autoantibodies and genetic risk markers.

Objectives:

Assemble a pattern of serologic biomarkers in combination with genetics to improve the identification of individuals at high risk to develop RA.

Methods:

The cohort included 827 serum samples from 601 individuals, followed within the Swiss multicenter cohort study SCREEN-RA of FDR [2]. FDR-RA were categorized into four groups according to the presence of symptoms and systemic autoimmunity associated with RA; 1: asymptomatic FDR-RA without anti-CCP or symptoms, 416 (69%); 2: FDR-RA with clinically suspect arthralgia (CSA) [3] or with signs of arthritis, without anti-CCP, 72 (12%); 3: FDR-RAs with no signs of arthritis, positive anti-CCP test, 55 (9%); 4: FDR with signs of arthritis or CSA, positive anti-CCP-test, 58 (10%).

Serum samples were analyzed for the presence of anti-CCP (IgG, IgA), RF (IgM, IgA) and anti-RA33 (IgM, IgA, IgG) using the EliATMinstrument platform (Phadia AB, Uppsala, Sweden).

Genetic measurements were performed using the AmpliSeqTMtechnology on the Ion GeneStudioTMinstruments (Thermo Fisher Scientific, Carlsbad, USA), covered variants were analyzed using an algorithm focusing on the identification of RA patients.

Results:

The overall prevalence of biomarkers, considering results above cutoff values, was 1% for anti-CCP IgG and IgA, 10% and 2% for RF IgM and RF IgA, respectively, and 6-15% for all three anti-RA33 isotypes. Several individuals had multiple positive serology tests (Fig 1): 3.6% (22) were positive for 2 tests and 1% (6) were positive for 3 or more tests. Among the 28 individuals positive for ≥2 tests, 17 (61%) were symptomatic.

Figure 1.

Distribution of positive serology within the different groups. No positivity (none), positive for one (1), equal or more than 2 (2-5) of the serologic tests.

Nine of 604 FDR-RA subsequently developed classifiable RA and were positive for serologic biomarkers before date of RA diagnosis (Table 1). The RA converters had a mean age of 39 years (24-75 yrs) and an average follow-up time within the study of 3.6 years (1-7 yrs).

Table 1.

Biomarker status of subsequent RA converters before date of diagnosis.

RA convertersCCP IgGCCP IgARF IgMRF IgARA33 total1+++++2+−++−3−−+−+4−−+−−5−−+−−6−−−−+7−−−−+8−−−−−9−−−−−

Using an algorithm to analyze the RA-associated genetic SNPs, we could highlight 48 FDR-RA (8%) with an increased genetic risk to develop RA. 15 out of 48 individuals (31%) at high genetic risk reported CSA, and 12 out of 48 individuals (25%) displayed signs of systemic autoimmunity associated with RA.

Conclusion:

When looking at FDR it could help to not only include anti-CCP autoantibody testing but also additional biomarkers like RF and anti-RA33. Furthermore, looking at the genetic risk factors could give additional information. The combination with the multi-variate profile could even improve the early diagnosis of these patients.

References:

[1]Kuo et al. Rheumatology 2017; 56:928933

[2]Finckh et al. Ann Rheum Dis 2011; 70: S3–282

[3]van Steenbergen HW, et al. Ann Rheum Dis 2017; 76:491–496

Disclosure of Interests:

Maresa Grundhuber Grant/research support from: Thermo Fisher Scientific, Employee of: Thermo Fisher Scientific, Isabel Gehring Grant/research support from: Thermo Fisher Scientific, Employee of: Thermo Fisher Scientific, Céline Lamacchia Grant/research support from: Thermo Fisher Scientific partially supported this study, Pascale Roux-Lombard: None declared, Michael Nissen Grant/research support from: Abbvie, Consultant of: Novartis, Lilly, Abbvie, Celgene and Pfizer, Speakers bureau: Novartis, Lilly, Abbvie, Celgene and Pfizer, Ulrich Walker Grant/research support from: Ulrich Walker has received an unrestricted research grant from Abbvie, Consultant of: Ulrich Walker has act as a consultant for Abbvie, Actelion, Boehringer Ingelheim, Bristol-Myers Squibb, Celgene, MSD, Novartis, Pfizer, Phadia, Roche, Sandoz, Sanofi, and ThermoFisher, Paid instructor for: Abbvie, Novartis, and Roche, Speakers bureau: Abbvie, Actelion, Bristol-Myers Squibb, Celgene, MSD, Novartis, Pfizer, Phadia, Roche, Sandoz, and ThermoFisher, Burkhard Moeller: None declared, Diego Kyburz Grant/research support from: Abbvie, Roche, Consultant of: Abbvie, BMS, Novartis, Pfizer, Roche, UCB, Gilead, Sanofi, Speakers bureau: Pfizer, BMS, Novartis, Abbvie, Adrian Ciurea Consultant of: Consulting and/or speaking fees from AbbVie, Bristol-Myers Squibb, Celgene, Eli Lilly, Merck Sharp & Dohme, Novartis and Pfizer., Maryam Poorafshar Grant/research support from: Thermo Fisher Scientific, Employee of: Thermo Fisher Scientific, Axel Finckh Grant/research support from: Pfizer: Unrestricted research grant, Eli-Lilly: Unrestricted research grant, Consultant of: Sanofi, AB2BIO, Abbvie, Pfizer, MSD, Speakers bureau: Sanofi, Pfizer, Roche, Thermo Fisher Scientific

Toward Earlier Diagnosis Using Combined eHealth Tools in Rheumatology: The Joint Pain Assessment Scoring Tool (JPAST) Project

Outcomes of patients with inflammatory rheumatic diseases have significantly improved over the last three decades, mainly due to therapeutic innovations, more timely treatment, and a recognition of the need to monitor response to treatment and to titrate treatments accordingly. Diagnostic delay remains a major challenge for all stakeholders. The combination of electronic health (eHealth) and serologic and genetic markers holds great promise to improve the current management of patients with inflammatory rheumatic diseases by speeding up access to appropriate care. The Joint Pain Assessment Scoring Tool (JPAST) project, funded by the European Union (EU) European Institute of Innovation and Technology (EIT) Health program, is a unique European project aiming to enable and accelerate personalized precision medicine for early treatment in rheumatology, ultimately also enabling prevention. The aim of the project is to facilitate these goals while at the same time, reducing cost for society and patients.

Molecular differentiation of Pantoea stewartii subsp. indologenes from subspecies stewartii and identification of new isolates from maize seeds

AIMS

Assays to detect Pantoea stewartii from maize seeds should include differentiation of P. stewartii subsp. stewartii and P. stewartii subsp. indologenes.

METHODS AND RESULTS

Previously published PCR primers for the identification of P. stewartii subsp. stewartii amplified signals from both subspecies using both conventional and quantitative PCR. In MALDI-TOF mass spectroscopy analysis with the Biotyper software (Bruker), subspecies stewartii and indologenes produced identical score values. Analysis against the Biotyper database produced similar score values for both subspecies. From the subtyping methods provided by the Biotyper software, only composite correlation indexing (CCI) separated both groups. By alignment of 16S rRNA sequences, no subspecies distinction was possible. To develop new techniques for the separation of these subspecies, the partial sequences of several housekeeping genes were compared. The type strains of the two subspecies showed characteristic single-nucleotide polymorphisms (SNPs) in the genes galE, glmS and recA. Other reference strains of P. stewartii subsp. stewartii followed the same nucleotide pattern, whereas known P. stewartii subsp. indologenes strains were different. Based on single-nucleotide polymorphisms in galE and recA, PCR primers were created to separate the subspecies by stepdown PCR analysis. Two putative P. stewartii strains were isolated from imported maize seeds. They were not virulent on maize seedlings, were positive in the indole assay with Kovacs reagent and identified as P. stewartii subsp. indologenes. The subspecies-specific PCR primers confirmed they were subspecies indologenes.

CONCLUSIONS

By stepdown PCR, P. stewartii subsp. indologenes can be differentiated from P. stewartii subsp. stewartii.

SIGNIFICANCE AND IMPACT OF THE STUDY

A possible detection of P. stewartii subsp. stewartii, the causative agent of Stewart's wilt of maize, in plant material by immunological or molecular assays must exclude contamination with P. stewartii subsp. indologenes, which would create false positives in seed tests and affect quarantine measurements.

Identification of Erwinia species isolated from apples and pears by differential PCR

Many pathogenic and epiphytic bacteria isolated from apples and pears belong to the genus Erwinia; these include the species E. amylovora, E. pyrifoliae, E. billingiae, E. persicina, E. rhapontici and E. tasmaniensis. Identification and classification of freshly isolated bacterial species often requires tedious taxonomic procedures. To facilitate routine identification of Erwinia species, we have developed a PCR method based on species-specific oligonucleotides (SSOs) from the sequences of the housekeeping genes recA and gpd. Using species-specific primers that we report here, differentiation was done with conventional PCR (cPCR) and quantitative PCR (qPCR) applying two consecutive primer annealing temperatures. The specificity of the primers depends on terminal Single Nucleotide Polymorphisms (SNPs) that are characteristic for the target species. These PCR assays enabled us to distinguish eight Erwinia species, as well as to identify new Erwinia isolates from plant surfaces. When performed with mixed bacterial cultures, they only detected a single target species. This method is a novel approach to classify strains within the genus Erwinia by PCR and it can be used to confirm other diagnostic data, especially when specific PCR detection methods are not already available. The method may be applied to classify species within other bacterial genera.

Genome comparison of the epiphytic bacteria Erwinia billingiae and E. tasmaniensis with the pear pathogen E. pyrifoliae

BACKGROUND

The genus Erwinia includes plant-associated pathogenic and non-pathogenic Enterobacteria. Important pathogens such as Erwinia amylovora, the causative agent of fire blight and E. pyrifoliae causing bacterial shoot blight of pear in Asia belong to this genus. The species E. tasmaniensis and E. billingiae are epiphytic bacteria and may represent antagonists for biocontrol of fire blight. The presence of genes that are putatively involved in virulence in E. amylovora and E. pyrifoliae is of special interest for these species in consequence.

RESULTS

Here we provide the complete genome sequences of the pathogenic E. pyrifoliae strain Ep1/96 with a size of 4.1 Mb and of the non-pathogenic species E. billingiae strain Eb661 with a size of 5.4 Mb, de novo determined by conventional Sanger sequencing and next generation sequencing techniques. Genome comparison reveals large inversions resulting from homologous recombination events. Furthermore, comparison of deduced proteins highlights a relation of E. billingiae strain Eb661 to E. tasmaniensis strain Et1/99 and a distance to E. pyrifoliae for the overall gene content as well as for the presence of encoded proteins representing virulence factors for the pathogenic species. Pathogenicity of E. pyrifoliae is supposed to have evolved by accumulation of potential virulence factors. E. pyrifoliae carries factors for type III secretion and cell invasion. Other genes described as virulence factors for E. amylovora are involved in the production of exopolysaccharides, the utilization of plant metabolites such as sorbitol and sucrose. Some virulence-associated genes of the pathogenic species are present in E. tasmaniensis but mostly absent in E. billingiae.

CONCLUSION

The data of the genome analyses correspond to the pathogenic lifestyle of E. pyrifoliae and underlines the epiphytic localization of E. tasmaniensis and E. billingiae as a saprophyte.