Identifying new monogenic autoimmune syndromes

More than half of all organ specific autoimmunity is directed towards hormon-producing organs. Many people suffer from two or more of these diseases, which often clusters in familie across generations. The current perception is that most of the diseases is caused by the total effect of variations in several risk genes interacting with environmental factors. We have, however, recently identified several hitherto unknown dominant mutations in the gene autoimmune regulator (AIRE). Instead of developing autoimmune polyendocrine syndrom type 1 (APS-1), a serious autosomal recessive disease starting during childhood, patients with dominant mutations have a milder phenotype with later debut. We have established and characterized, in collaboration with The Weizmann Institute in Israel, several Crispr/Cas9 mouse models. We were able to show that heterozygous dominant mutations affects Aire regulated transcription in a similar manner as homozygous recessive variants (paper in review, J Experimental Medicine). In Bergen, we are also working with two similar models, including a splice mutation found in two families with mild disease. Furthermore, we are studying AIRE variants in patients with serious Covid-19 disease. Ten percent of these patients have autoantibodies against interferons, in common with APS-1 patients. The results were published in Science 25 September (Bastard et al). We have recently started two new projects where with the aim to study circulating immune cells in patients with APS-1 with 10x single cell technology, working together with the Core Facilities for Sequencing and Bioinformatics to build local competence. This technology allows us to study the gene expression in a large number of single cells and at the same time sequence the T-cell receptors of the same cells. We believe this will uncover formerly unknown irregularities in the immune system of APS-1 patients. We have data for 4 patients and 4 controls, and by the end of 2020 we should have run 4 more in each group. In the second projects we will establish a standardised high throughput analysis to phenotype immune cells across the entire APS-1 patient group. CyTOF technology allows us to measure 37 different cell markers simultanously, and thus detect cell populations down to the single cell level. Setting up such a big panel is time consuming, but it should be completed by the end of 2020, at which time we will commence running patient samples as routine. In collaboration with Karolinska Insitutet in Sweden, we have completed the first genomewide association study (GWAS) on autoimmune adrenal insufficiency with 1223 patients and 4097 controls. This is, by far, the largest genetic study ever performed on this disease. A revised version of the paper is under review in Nature Communications. The study shows that a coding variant of Aire increases the risk of autoimmune adrenal sufficiency. We have already started follow-up studies to characterize the functional effect of this variant, analyze its crystal structure and generate a Crispr/Cas9 mouse model. We will also use the data from the GWAS to detect sex-differential variants on the X-chromosome (XWAS), mitochondrial DNA variants, copy number variations, and create a polygenic risk score. Another finding in the GWAS is that known autoimmunity genes, such as CTLA-4, also predispose to adrenal disease. CTLA-4 is an inhibitory receptor on T-cells, and is especially important for T-cells that dampen the immune response, the so-called regulatory T-cells. We will study cells from both patients and controls with and without the CTLA-4 risk variant to expose the functional effect of the variant with the aim to \ use these variants/genes as future therapeutic targets. We are also looking for new monogenic causes of autoimmunity. To this end, we will study almost 50 Norwegian and Swedish families with high occurrence of adrenal insufficiency and related autoimmune diseases. Data from the first 200 patients will be available for analysis in the authum of 2020 and will be analysed during 2021.

From our extensive genetic study, we have mapped up to 40% of the genetic risk for AAD. With these data, we have developed a polygenic risk score analysis (PRA) to assess the relative risk to develop ADD. Preliminary results from the whole genome analysis on extreme cases (families or children) found no novel monogenic forms, however the non-afflicted family members have similar PRA scores as sporadic AAD patients. Thus, we should be able to provide clinically relevant genetic risk assessment of developing ADD in at-risk populations. Combining single cell sequencing of immune cells with phenotypic immune profiling in both APS-1 and Addison patients, will provide us with an unique framework for understanding the autoimmunity mechanism and feed into future steps of novel therapeutic approaches to autoimmune diseases. The insight learned from gene to function studies can be translated into designing more efficient and cost-effective diagnostic and personalized immunotherapy

Autoimmune diseases affect several hundreds of millions of patients worldwide. Collectively, they are among the leading causes of morbidity, chronic illness and death. Autoimmunity directed towards the thyroid, pancreatic islets, gastric mucosa, and adrenal cortex, accounts for more than half of all forms of organ-specific autoimmunity in the USA and Europe. Many individuals are affected by two or more of these diseases with familial clustering. Current dogma dictates that the vast majority of these disease are caused by the collective effects of multiple susceptibly genes (30-50)in interaction with environmental factors. We recently identified a number of hitherto unknown dominant mutations in the autoimmune regulator (AIRE) gene. Instead of the severe autosomal recessive childhood onset autoimmune polyendocrine syndrome type 1 (APS-1), these individuals presented with a milder phenotype with later onset, often masquerading as common organ-specific autoimmunity. Based on these and similar findings we now hypothesize that single gene mutations in key pathways involved in immunological tolerance are much more common than previously acknowledged. Bringing together leading experts in the fields of immunology, endocrinology, genetics, and bioinformatics with access to a European network of patient registries and biobanks, state-of-the-art genetic and bioinformatics tools and technologies, we aim to identify new monogenic causes of autoimmunity, to unravel the pathways involved, and to describe their clinical presentation and epidemiology. The findings will provide new insights into the fundamental questions on how organ-specific autoimmune diseases arise and possibly why endocrine tissues and glands are particularly often targeted, as well as deliver improved and personalized care for patients with organ-specific autoimmune diseases.