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

Aqp0a Regulates Suture Stability in the Zebrafish Lens

Purpose

To investigate the roles of Aquaporin 0a (Aqp0a) and Aqp0b in zebrafish lens development and transparency.

Methods

CRISPR/Cas9 gene editing was used to generate loss-of-function deletions in zebrafish aqp0a and/or aqp0b. Wild type (WT), single mutant, and double mutant lenses were analyzed from embryonic to adult stages. Lens transparency, morphology, and growth were assessed. Immunohistochemistry was used to map protein localization as well as to assess tissue organization and distribution of cell nuclei.

Results

aqp0a^−/− and/or aqp0b^−/− cause embryonic cataracts with variable penetrance. While lenses of single mutants of either gene recover transparency in juveniles, double mutants consistently form dense cataracts that persist in adults, indicating partially redundant functions. Double mutants also reveal redundant Aqp0 functions in lens growth. The nucleus of WT lenses moves from the anterior pole to the lens center with age. In aqp0a^−/− mutants, the nucleus fails to centralize as it does in WT or aqp0b^−/− lenses, and in double mutant lenses there is no consistent lens nuclear position. In addition, the anterior sutures of aqp0a^−/−, but not aqp0b^−/− mutants, are unstable resulting in failure of suture maintenance at older stages and anterior polar opacity.

Conclusions. Zebrafish Aqp0s have partially redundant functions, but only Aqp0a promotes suture stability, which directs the lens nucleus to centralize, failure of which results in anterior polar opacity. These studies support the hypothesis that the two Aqp0s subfunctionalized during fish evolution and that Aqp0-dependent maintenance of the anterior suture is essential for lens transparency.

An ongoing role for Wnt signaling in differentiating melanocytes in vivo

A role for Wnt signaling in melanocyte specification from neural crest is conserved across vertebrates, but possible ongoing roles in melanocyte differentiation have received little attention. Using a systems biology approach to investigate the gene regulatory network underlying stable melanocyte differentiation in zebrafish highlighted a requirement for a positive-feedback loop involving the melanocyte master regulator Mitfa. Here, we test the hypothesis that Wnt signaling contributes to that positive feedback. We show firstly that Wnt signaling remains active in differentiating melanocytes and secondly that enhanced Wnt signaling drives elevated transcription of mitfa. We show that chemical activation of the Wnt signaling pathway at early stages of melanocyte development enhances melanocyte specification as expected, but importantly that at later (differentiation) stages, it results in altered melanocyte morphology, although melanisation is not obviously affected. Downregulation of Wnt signaling also results in altered melanocyte morphology and organization. We conclude that Wnt signaling plays a role in regulating ongoing aspects of melanocyte differentiation in zebrafish.

Spermidine, but not spermine, is essential for pigment pattern formation in zebrafish

Polyamines are small poly-cations essential for all cellular life. The main polyamines present in metazoans are putrescine, spermidine and spermine. Their exact functions are still largely unclear; however, they are involved in a wide variety of processes affecting cell growth, proliferation, apoptosis and aging. Here we identify idefix, a mutation in the zebrafish gene encoding the enzyme spermidine synthase, leading to a severe reduction in spermidine levels as shown by capillary electrophoresis-mass spectrometry. We show that spermidine, but not spermine, is essential for early development, organogenesis and colour pattern formation. Whereas in other vertebrates spermidine deficiency leads to very early embryonic lethality, maternally provided spermidine synthase in zebrafish is sufficient to rescue the early developmental defects. This allows us to uncouple them from events occurring later during colour patterning. Factors involved in the cellular interactions essential for colour patterning, likely targets for spermidine, are the gap junction components Cx41.8, Cx39.4, and Kir7.1, an inwardly rectifying potassium channel, all known to be regulated by polyamines. Thus, zebrafish provide a vertebrate model to study the in vivo effects of polyamines.

Summary: We show that the polyamine spermidine, but not spermine, in addition to more general functions during early development, also specifically regulates colour pattern formation in adult zebrafish.

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.

The zebrafish mutant bumper shows a hyperproliferation of lens epithelial cells and fibre cell degeneration leading to functional blindness

The development of the eye lens is one of the classical paradigms of induction during embryonic development in vertebrates. But while there have been numerous studies aimed at discovering the genetic networks controlling early lens development, comparatively little is known about later stages, including the differentiation of secondary lens fibre cells. The analysis of mutant zebrafish isolated in forward genetic screens is an important way to investigate the roles of genes in embryogenesis. In this study we describe the zebrafish mutant bumper (bum), which shows a transient, tumour-like hyperproliferation of the lens epithelium as well as a progressively stronger defect in secondary fibre cell differentiation, which results in a significantly reduced lens size and ectopic location of the lens within the neural retina. Interestingly, the initial hyperproliferation of the lens epithelium in bum spontaneously regresses, suggesting this mutant as a valuable model to study the molecular control of tumour progression/suppression. Behavioural analyses demonstrate that, despite a morphologically normal retina, larval and adult bum(-/-) zebrafish are functionally blind. We further show that these fish have defects in their craniofacial skeleton with normal but delayed formation of the scleral ossicles within the eye, several reduced craniofacial bones resulting in an abnormal skull shape, and asymmetric ectopic bone formation within the mandible. Genetic mapping located the mutation in bum to a 4cM interval on chromosome 7 with the closest markers located at 0.2 and 0cM, respectively.

Large-scale mapping of mutations affecting zebrafish development

Background

Large-scale mutagenesis screens in the zebrafish employing the mutagen ENU have isolated several hundred mutant loci that represent putative developmental control genes. In order to realize the potential of such screens, systematic genetic mapping of the mutations is necessary. Here we report on a large-scale effort to map the mutations generated in mutagenesis screening at the Max Planck Institute for Developmental Biology by genome scanning with microsatellite markers.

Results

We have selected a set of microsatellite markers and developed methods and scoring criteria suitable for efficient, high-throughput genome scanning. We have used these methods to successfully obtain a rough map position for 319 mutant loci from the Tübingen I mutagenesis screen and subsequent screening of the mutant collection. For 277 of these the corresponding gene is not yet identified. Mapping was successful for 80 % of the tested loci. By comparing 21 mutation and gene positions of cloned mutations we have validated the correctness of our linkage group assignments and estimated the standard error of our map positions to be approximately 6 cM.

Conclusion

By obtaining rough map positions for over 300 zebrafish loci with developmental phenotypes, we have generated a dataset that will be useful not only for cloning of the affected genes, but also to suggest allelism of mutations with similar phenotypes that will be identified in future screens. Furthermore this work validates the usefulness of our methodology for rapid, systematic and inexpensive microsatellite mapping of zebrafish mutations.