Differential Microbial Pattern Description in Subjects with Autoimmune-Based Thyroid Diseases: A Pilot Study.

Isabel Cornejo-Pareja,Ana M Gómez-Pérez,Isabel Moreno-Indias,Patricia Ruiz-Limón,Francisco J Tinahones,María Molina-Vega

doi:10.3390/jpm10040192

Abstract

The interaction between genetic susceptibility, epigenetic, endogenous, and environmental factors play a key role in the initiation and progression of autoimmune thyroid diseases (AITDs). Studies have shown that gut microbiota alterations take part in the development of autoimmune diseases. We have investigated the possible relationship between gut microbiota composition and the most frequent AITDs. A total of nine Hashimoto’s thyroiditis (HT), nine Graves–Basedow’s disease (GD), and 11 otherwise healthy donors (HDs) were evaluated. 16S rRNA pyrosequencing and bioinformatics analysis by Quantitative Insights into Microbial Ecology and Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) were used to analyze the gut microbiota. Beta diversity analysis showed that gut microbiota from our groups was different. We observed an increase in bacterial richness in HT and a lower evenness in GD in comparison to the HDs. GD showed a significant increase of Fusobacteriaceae, Fusobacterium and Sutterella compared to HDs and the core microbiome features showed that Prevotellaceae and Prevotella characterized this group. Victivallaceae was increased in HT and was part of their core microbiome. Streptococcaceae, Streptococcus and Rikenellaceae were greater in HT compared to GD. Core microbiome features of HT were represented by Streptococcus, Alistipes, Anaerostipes, Dorea and Haemophilus. Faecalibacterium decreased in both AITDs compared to HDs. PICRUSt analysis demonstrated enrichment in the xenobiotics degradation, metabolism, and the metabolism of cofactors and vitamins in GD patients compared to HDs. Moreover, correlation studies showed that some bacteria were widely correlated with autoimmunity parameters. A prediction model evaluated a possible relationship between predominant concrete bacteria such as an unclassified genus of Ruminococcaceae, Sutterella and Faecalibacterium in AITDs. AITD patients present altered gut microbiota compared to HDs. These alterations could be related to the immune system development in AITD patients and the loss of tolerance to self-antigens.

Highlights

Autoimmune thyroid diseases (AITDs) are the most common organ-specific autoimmune disorders
TPO-Ab was significantly increased in Hashimoto’s thyroiditis (HT) and TSI-Ab was significantly increased in Graves’ disease (GD)
Our observations demonstrated a gut dysbiosis in AITD patients, may be able to contribute to thyroid disease development

Summary

Introduction

Autoimmune thyroid diseases (AITDs) are the most common organ-specific autoimmune disorders. Within AITDs, Hashimoto’s thyroiditis and Graves–Basedow’s disease are the most frequent conditions. Hashimoto’s thyroiditis (HT) is identified by lymphocytes infiltration in the thyroid gland which leads to the destruction of thyroid follicles, and the production of autoantibodies against thyroid peroxidase (TPO, 90–95%) and thyroglobulin (TG, 20–50%) [1,2]. The etiology of AITDs is thought to be multifactorial, arising from an interaction between genetic susceptibility, epigenetic, and various endogenous and environmental factors [4]. Several studies have provided evidence for genetic factors, the concordance rate for AITDs among monozygotic twins is in the range of 35–55% compared with 3% in dizygotic twins, emphasizing that other important factors, such as the environment, are implicated in the pathogenesis of AITD [5,6,7]

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