Microbiota and Immune SignatureS of Graves’ disease and Orbitopathy (MISS.GO)

Graves’ disease (GD) is a common autoimmune disease causing hyperthyroidism and in 30-50% of cases it is associated with Graves’ orbitopathy (GO), an inflammation of orbital tissues causing disfigurement and visual problems. Some risk factors for GD and GO are known, however an effective model able to predict which GD patients will develop GO is missing. In fact the etiopathogenesis is still in part unclear, and seems to involve gut microbiota alterations, as well as immune dysregulation, in particular an imbalance of T Helper 17 and T Regulatory cell homeostasis, that support and obstacle the autoimmune process, respectively. The international EU-FP7 funded study “Investigation of Novel biomarkers and Definition of the role of the microbiome In Graves’ Orbitopathy” (INDIGO), also including UO1 (UNIMI), investigated the role of gut microbiota in GD and GO diseases by 16S rRNA sequencing and identified an imbalance in commensal bacteria (reduced Bacteroidetes, increased Firmicutes) in both murine models and human studies. Other authors performed a paired analysis of microbiome and lymphocytes, however they studied only GD patients and immunophenotyped peripheral lymphocytes, not organ specific. This project will allow great advances in the understanding of microbiota and immune alterations underpinning GD and GO for several reasons. First the INDIGO samples, stored within UO1 (UNIMI), will be re-analysed with advanced Shotgun sequencing to obtain a more informative microbiome composition, allowing to reach a deeper taxonomic level down to species, to detect low abundant species and to investigate also microbiome components other than bacteria. Second, new GD and GO patients, as well as non autoimmune controls, will be prospectively recruited to analyse their microbiota in parallel with their immune alterations. The breakthrough consists in being able to sample and immunophenotype lymphocytes obtained directly from the target organs of autoimmunity (thyroid and neck lymph nodes) thanks to ultrasound guided fine-needle aspiration sampling, instead of those peripheral that lack disease specificity. Such advanced technique is already running within UO1 (UNIMI) and preliminary results have been produced. Furthermore, in addition to advanced microbiome analysis by Shotgun sequencing, the microbiota analysis of these patients will be enriched with metabolomics and metaproteomics data, thanks to the expertise of UO3 (UNIPO). The UO2 (CNR) will take care of data analysis, combining the microbiota and immune signatures to distinguish GD, GO patients and controls and to develop a model able to predict which GD patients are at risk to develop GO. Indeed, an early diagnosis is a key factor to improve the disease prognosis, ameliorating patients’ quality of life and reducing social and health costs. Furthermore, the knowledge deriving from this project will help to identify possible novel targets of therapy of GD and GO (i.e. probiotics, immunotherapy).