Considerations for Optimal Trial Design for Rheumatoid Arthritis Prevention Studies

Identification of multiple novel susceptibility genes associated with autoimmune thyroid disease

Background

Autoimmune thyroid disease (AITD) is induced by various factors, including inheritability, which regulates gene expression. Multiple loci correlated with AITD have been discovered utilizing genome-wide association studies (GWASs). Nevertheless, demonstrating the biological relevance and function of these genetic loci is difficult.

Methods

The FUSION software was utilized to define genes that were expressed differentially in AITD using a transcriptome-wide association study (TWAS) method in accordance with GWAS summary statistics from the largest genome-wide association study of 755,406 AITD individuals (30,234 cases and 725,172 controls) and levels of gene expression from two tissue datasets (blood and thyroid). Further analyses were performed such as colocalization, conditional, and fine-mapping analyses to extensively characterize the identified associations, using functional mapping and annotation (FUMA) to conduct functional annotation of the summary statistics of 23329 significant risk SNPs (P < 5 × 10^-8) recognized by GWAS, together with summary-data-based mendelian randomization (SMR) for identifying functionally related genes at the loci in GWAS.

Results

There were 330 genes with transcriptome-wide significant differences between cases and controls, and the majority of these genes were new. 9 of the 94 unique significant genes had strong, colocalized, and potentially causal correlations with AITD. Such strong associations included CD247, TPO, KIAA1524, PDE8B, BACH2, FYN, FOXK1, NKX2-3, and SPATA13. Subsequently, applying the FUMA approach, novel putative AITD susceptibility genes and involved gene sets were detected. Furthermore, we detected 95 probes that showed strong pleiotropic association with AITD through SMR analysis, such as CYP21A2, TPO, BRD7, and FCRL3. Lastly, we selected 26 genes by integrating the result of TWAS, FUMA, and SMR analysis. A phenome-wide association study (pheWAS) was then carried out to determine the risk of other related or co-morbid phenotypes for AITD-related genes.

Conclusions

The current work provides further insight into widespread changes in AITD at the transcriptomic level, as well as characterized the genetic component of gene expression in AITD by validating identified genes, establishing new correlations, and uncovering novel susceptibility genes. Our findings indicate that the genetic component of gene expression plays a significant part in AITD.

How to enhance recruitment of individuals at risk of rheumatoid arthritis into trials aimed at prevention: understanding the barriers and facilitators

OBJECTIVES

Several trials to test the efficacy of a pharmacological intervention aimed at primary prevention of rheumatoid arthritis (RA) are ongoing or have recently been completed. A common issue in these trials is the severe difficulty with patient recruitment. In order to enhance recruitment, this qualitative study identified barriers and facilitators of individuals at risk of RA to participate in a prevention trial.

METHODS

Individuals at risk of developing RA (ie, arthralgia with anticitrullinated protein antibodies and/or rheumatoid factor without arthritis), who had previously been asked to participate in a prevention trial, participated in focus group discussions (n=18) exploring their facilitators and barriers for trial participation. Thematic analysis identified factors that were important in at-risk individuals' decision about trial participation.

RESULTS

The prospect of personal benefit, the acknowledgement of one's symptoms and the desire to contribute to society facilitated trial participation. In contrast, misconception about what it means to be at risk, or about the aim of the prevention trial, negative views on trial medication, and a low perceived urgency to act on the possibility of developing RA versus a high perceived burden of participating in a trial discouraged participation.

CONCLUSIONS

To enhance inclusion in trials aimed to prevent RA, the results suggest to use strategies such as optimising education about RA, personal risk, trial aim and trial medication, explicitly addressing misconceptions and concerns, using tools to improve information provision, limiting study burden in trial design and encouraging physicians to mention trial participation.

Patients' and rheumatologists' perceptions on preventive intervention in rheumatoid arthritis and axial spondyloarthritis

BACKGROUND

Individuals at risk of developing rheumatoid arthritis (RA) may benefit from lifestyle or pharmacological interventions aimed at primary prevention. The same may apply to individuals at risk of axial spondyloarthritis (axSpA). Our aim was to investigate and compare the willingness of individuals at risk of RA or axSpA and rheumatologists to initiate preventive intervention.

METHODS

Individuals at risk of RA (arthralgia and anti-citrullinated protein antibodies and/or rheumatoid factor positivity without arthritis (RA-risk cohort; n = 100)), axSpA (first-degree relatives of HLA-B27-positive axSpA patients (SpA-risk cohort; n = 38)), and Dutch rheumatologists (n = 49) completed a survey on preventive intervention which included questions about disease perception, lifestyle intervention, and preventive medication.

RESULTS

At-risk individuals reported willingness to change median 7 of 13 lifestyle components in the areas of smoking, diet, and exercise. In contrast, 35% of rheumatologists gave lifestyle advice to ≥ 50% of at-risk patients. The willingness to use 100% effective preventive medication without side effects was 53% (RA-risk), 55% (SpA-risk), and 74% (rheumatologists) at 30% disease risk which increased to 69% (RA-risk) and 92% (SpA-risk and rheumatologists) at 70% risk. With minor side effects, willingness was 26%, 29%, and 31% (at 30% risk) versus 40%, 66%, and 76% (at 70% risk), respectively.

CONCLUSIONS

Risk perception and willingness to start preventive intervention were largely similar between individuals at risk of RA and axSpA. Although the willingness to change lifestyle is high among at-risk individuals, most rheumatologists do not advise them to change their lifestyle. In contrast, rheumatologists are more willing than at-risk patients to start preventive medication.

FLT3 stop mutation increases FLT3 ligand level and risk of autoimmune thyroid disease

Autoimmune thyroid disease is the most common autoimmune disease and is highly heritable¹. Here, by using a genome-wide association study of 30,234 cases and 725,172 controls from Iceland and the UK Biobank, we find 99 sequence variants at 93 loci, of which 84 variants are previously unreported^2-7. A low-frequency (1.36%) intronic variant in FLT3 (rs76428106-C) has the largest effect on risk of autoimmune thyroid disease (odds ratio (OR) = 1.46, P = 2.37 × 10^-24). rs76428106-C is also associated with systemic lupus erythematosus (OR = 1.90, P = 6.46 × 10^-4), rheumatoid factor and/or anti-CCP-positive rheumatoid arthritis (OR = 1.41, P = 4.31 × 10^-4) and coeliac disease (OR = 1.62, P = 1.20 × 10^-4). FLT3 encodes fms-related tyrosine kinase 3, a receptor that regulates haematopoietic progenitor and dendritic cells. RNA sequencing revealed that rs76428106-C generates a cryptic splice site, which introduces a stop codon in 30% of transcripts that are predicted to encode a truncated protein, which lacks its tyrosine kinase domains. Each copy of rs76428106-C doubles the plasma levels of the FTL3 ligand. Activating somatic mutations in FLT3 are associated with acute myeloid leukaemia⁸ with a poor prognosis and rs76428106-C also predisposes individuals to acute myeloid leukaemia (OR = 1.90, P = 5.40 × 10^-3). Thus, a predicted loss-of-function germline mutation in FLT3 causes a reduction in full-length FLT3, with a compensatory increase in the levels of its ligand and an increased disease risk, similar to that of a gain-of-function mutation.