THU0001 GENOME-WIDE ASSOCIATION STUDY ON JOINT EROSIONS IN RHEUMATOID ARTHRITIS SUPPORTS DIFFERENTIAL PATHOLOGICAL MECHANISMS ACCORDING TO ANTI-CCP STATUS

Background:

Joint damage is the pathological hallmark of rheumatoid arthritis (RA). To identify the genetic variation associated with a higher level of erosions has proven elusive.

Objectives:

The objective of the present study was to perform a genome-wide association study on joint damage in a cohort of RA patients of the Spanish population. Our aims were to provide independent validation of previously reported variants and to identify new candidate risk loci. A stratified analysis was performed based on positivity to ACPA status.

Methods:

A total of 1,135 patients diagnosed with RA using the ACR-EULAR criteria recruited by the IMID Consortium were genotyped using a 550,000 single-nucleotide polymorphism array. Additional SNPs were imputed using the 1KG genome data. Joint damage was performed using the S-score, a simplified radiographic erosion score that has a high correlation with the Sharp-van der Hejde score (1). Association testing of SNPs with joint damage was performed via linear regression with the addition of the years of evolution as covariate. The two main components of genetic variation were also added to adjust for potential population stratification. A total of 50 SNPs representing previously reported loci associated with joint damage were selected. Genetic association was also performed at the pathway level using Pascal.

Results:

45 out of 50 SNPs representing 31 previously reported loci for joint damage could be satisfactorily imputed. Association testing of the whole patient cohort replicated the association withIL2RAandTRAF1. Of relevance, after stratifying for anti-CCP five new loci were replicated:KIF5AandSOSTin ACPA-positive RA andCD40, DKK1andTNFin ACPA-negative RA.IL2RAwas only significant in the ACPA-positive group andTRAF1was not significant in either strata. GWAS on the ACPA-positive cohort and on the ACPA-negative group identified n=7 and n=18 loci with P-values < 1x10-5, respectively. From these, however, only 1 SNP showed nominal significant association in the other patient group. Based on this evidence, we performed a pathway-based analysis to understand the biological mechanisms underlying this difference. Pathway analysis showed 52 biological processes associated with joint damage in ACPA-negative RA and 32 pathways in the ACPA-positive group, with only two shared biological processes between the two groups. Fc Gamma receptor mediated phagocytosis was the topmost biological process associated with erosions specifically in ACPA-negative RA and Signalling by Fibroblast Growth Factor mutants was the top process specific for ACPA-positive patients.

Conclusion:

The results from our study provide suggestive evidence that the genetic basis for joint damage is different according to the presence of ACPA. Replication of the new candidate loci in an independent patient cohort is underway.

References:

[1]Lopez-Lasanta, M., Julià, A., Maymó, J., Fernández-Gutierrez, B., Ureña-Garnica, I., Blanco, F. J., ... & Tornero, J. (2015). Variation at interleukin-6 receptor gene is associated to joint damage in rheumatoid arthritis.Arthritis research & therapy,17(1), 242.

Disclosure of Interests:

Antonio Julià: None declared, Francisco Blanco: None declared, Benjamin Fernandez: None declared, Antonio Gonzalez: None declared, Juan D: None declared, Joan Maymó: None declared, Mercedes Alperi-López: None declared, Alejandro Olive: None declared, Héctor Corominas Speakers bureau: Abbvie, Lilly, Pfizer, Roche, Victor Martinez Taboada: None declared, Isidoro González-Álvaro Grant/research support from: Roche Laboratories, Consultant of: Lilly, Sanofi, Paid instructor for: Lilly, Speakers bureau: Abbvie, MSD, Roche, Lilly, Antonio Fernandez-Nebro: None declared, Alba Erra: None declared, Simon Sánchez Fernandez: None declared, Núria Palau: None declared, Maria Lopez Lasanta: None declared, Adrià Aterido: None declared, Jesús Tornero: None declared, Sara Marsal: None declared

Insulin and Leptin Signaling in Placenta from Gestational Diabetic Subjects

Insulin and leptin receptors are known to share signaling pathways, such as JAK2/STAT-3 (Janus kinase2/signal transduction and activator of transcription3), MAPK (Mitogen activated protein kinase), and PI3K (phosphoinositide 3-kinase). Both positive and negative cross-talk have been previously found in different cellular systems. Gestational diabetes (GDM) is a pathophysiological state with high circulating levels of both insulin and leptin. We have previously found that these 3 signaling pathways are activated in placenta from GDM patients to promote translation, involving the activation of leptin receptor. Now, we have tested the hypothesis that both leptin and insulin receptors might contribute to this activation in a positive way that may become negative when the system is overactivated. We studied the activation of leptin and insulin receptors in placenta from GDM and healthy pregnancies. We have also performed in vitro studies with insulin and leptin stimulation of trophoblast explants from healthy placenta. We have found that both leptin and insulin receptors are activated in placenta from GDM. In vitro stimulation of trophoblast explants with both leptin and insulin at submaximal doses (0.1 nM) potentiated the activation of signaling, whereas preincubation with maximal concentrations of insulin (10 nM) and further stimulation with leptin showed negative effect. Trophoblastic explants from GDM placenta, which presented high signaling levels, had a negative signaling effect when further incubated in vitro with leptin. In conclusion, insulin and leptin receptors have positive effects on signaling, contributing to high signaling levels in GDM placenta, but insulin and leptin have negative effects upon overstimulation.

Repair of erosions in patients with rheumatoid arthritis treated with etanercept: magnetic resonance imaging findings after 1 year of follow-up

OBJECTIVES

To monitor repair of bone erosions using magnetic resonance imaging (MRI) in patients with rheumatoid arthritis (RA) during etanercept combination therapy.

METHOD

The study population comprised 29 RA patients [biologic-naïve, 28-joint Disease Activity Score (DAS28) ≥ 3.2] starting etanercept combination therapy with disease-modifying anti-rheumatic drugs (DMARDs) and completing the 1-year study period with the same treatment. Clinical and laboratory assessments and MRI of the hand were performed at baseline and at 1 year. MRI findings were scored by two readers using the Rheumatoid Arthritis MRI Scoring System (RAMRIS). Both readers were blind to the chronological order of the MRI scans, the identity of the patients, and clinical and other imaging data. Tenosynovitis was also scored. The intra- and inter-reader intraclass correlation coefficients (ICCs) were calculated, along with the sensitivity to change with the smallest detectable difference (SDD). Repair of erosions was defined as a RAMRIS score of at least 1 point lower than baseline.

RESULTS

The mean RAMRIS score for erosions did not change but all other inflammatory MRI parameters decreased significantly. In 19 patients, the RAMRIS score for erosions remained unchanged after 1 year. In five patients the score decreased after 1 year, although the decrease exceeded the SDD in only one patient (3.4%).

CONCLUSIONS

Etanercept combined with DMARDs stopped the progression of erosions, as measured by the RAMRIS, in 82.8% of our RA patients and occasional repair of bone erosions occurred after 1 year of treatment.

Alopecia areata as another immune-mediated disease developed in patients treated with tumour necrosis factor-α blocker agents: Report of five cases and review of the literature

BACKGROUND

Tumour necrosis factor antagonists (anti-TNF-α) have demonstrated the efficacy in different chronic immune inflammatory disorders. Within the spectrum of adverse events, autoimmune diseases have been observed, including cases of alopecia areata (AA).

OBJECTIVES

The objective of the study is to characterize AA developed during anti-TNF-α therapy.

METHODS

We present five new cases and review all the cases reported in the literature (eleven).

RESULTS

One third of the cases had a positive (personal or family) history of AA. Most of them presented with rapid extensive AA, usually involving the ophiasis area. Prognosis was usually poor, with slight response to treatments. In the cases where anti-TNF-α therapy was maintained, the course did not seem to change.

CONCLUSIONS

Although rare, AA developed during anti-TNF-α therapy might be more frequent than suggested by reports of isolated cases. Personal and family history of autoimmune disease might alert clinicians to their possible development or relapse once the anti-TNF-α therapy is started.

Adenosine deaminase activity in rheumatoid pleural effusion

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