Search

Context: Gut bacteria can influence host immune responses but little is known about their role in tolerance-loss mechanisms in Graves disease (GD; hyperthyroidism caused by autoantibodies, TRAb, to the thyrotropin receptor, TSHR) and its progression to Graves orbitopathy (GO). Objective: This work aimed to compare the fecal microbiota in GD patients, with GO of varying severity, and healthy controls (HCs). Methods: Patients were recruited from 4 European countries (105 GD patients, 41 HCs) for an observational study with cross-sectional and longitudinal components. Results: At recruitment, when patients were hyperthyroid and TRAb positive, Actinobacteria were significantly increased and Bacteroidetes significantly decreased in GD/GO compared with HCs. The Firmicutes to Bacteroidetes (F:B) ratio was significantly higher in GD/GO than in HCs. Differential abundance of 15 genera was observed in patients, being most skewed in mild GO. Bacteroides displayed positive and negative correlations with TSH and free thyroxine, respectively, and was also significantly associated with smoking in GO; smoking is a risk factor for GO but not GD. Longitudinal analyses revealed that the presence of certain bacteria (Clostridiales) at diagnosis correlated with the persistence of TRAb more than 200 days after commencing antithyroid drug treatment. Conclusion: The increased F:B ratio observed in GD/GO mirrors our finding in a murine model comparing TSHR-immunized with control mice. We defined a microbiome signature and identified changes associated with autoimmunity as distinct from those due to hyperthyroidism. Persistence of TRAb is predictive of relapse; identification of these patients at diagnosis, via their microbiome, could improve management with potential to eradicate Clostridiales. [ABSTRACT FROM AUTHOR]

Apart from evaluating orbital inflammation in Graves' ophthalmopathy (GO), somatostatin (SST) analogs have been proposed as a therapy, but recent trials were disappointing. We aimed to measure somatostatin receptor (SSTR) expression in orbital tissues ex vivo and determine whether the new broad-affinity analog SOM230 might be of therapeutic use. Orbital adipose/connective tissues from 29 GO patients and 10 normal individuals were analyzed. Transcripts were quantified using SYBR Green and a light cycler. In vitro models were used to investigate whether thyrotropin receptor activation (as occurs via thyroid stimulating antibodies) or adipogenesis affected SSTR expression in primary preadipocytes and to compare the biological acuvity of octreofide and SOM230 in their modulation. The expression of SSTR 1 was significantly higher in GO patients than normal controls (P = 0.024). Although differences in the expression of SSTR2 were not significant, 39% of GO samples had levels above the 97th percentile of the controls. SSTR3, -4, and -5 were at or below the limit of detection (LOD). The lymphocyte contribution was minimal, since CD3[alpha] transcripts were at the LOD. TSH receptor activation did not modulate SSTR expression. An in vitro model of adipogenesis indicated upregulation of SSTR1 and SSTR2 during differentiation. SOM230 produced significantly greater inhibition of orbital preadipocyte proliferation than octreotide. Ex vivo analysis of orbital tissues reveals upregulation of SSTR1 and -2 in a group of GO patients. Adipogenesis, a process occurring in GO orbits, provides one possible explanation for some of the observed increase. somatostatin analogs; adipogenesis

Context Depot-specific expansion of orbital adipose tissue (OAT) in Graves orbitopathy (GO; an autoimmune condition producing proptosis, visual impairment and reduced quality of life) is associated with fatty acid (FA)-uptake–driven adipogenesis in preadipocytes/fibroblasts (PFs). Objective This work sought a role for mitochondria in OAT adipogenesis in GO. Methods Confluent PFs from healthy OAT (OAT-H), OAT from GO (OAT-GO) and white adipose tissue in culture medium compared with culture medium containing a mixed hormonal cocktail as adipogenic medium (ADM), or culture-medium containing FA-supplementation, oleate:palmitate:linoleate (45:30:25%) with/without different concentration of mitochondrial biosubstrate adenosine 5′-diphosphate/guanosine 5′-diphosphate (ADP/GDP), AICAR (adenosine analogue), or inhibitor oligomycin-A for 17 days. Main outcome measures included oil-red-O staining and foci count of differentiated adipocytes for in vitro adipogenesis, flow cytometry, relative quantitative polymerase chain reaction, MTS-assay/106 cells, total cellular-ATP detection kit, and Seahorse-XFe96-Analyzer for mitochondria and oxidative-phosphorylation (OXPHOS)/glycolysis-ATP production analysis. Results During early adipogenesis before adipocyte formation (days 0, 4, and7), we observed OAT-specific cellular ATP production via mitochondrial OXPHOS in PFs both from OAT-H and OAT-GO, and substantially disrupted OXPHOS-ATP/glycolysis-ATP production in PFs from OAT-GO, for example, a 40% reduction in OXPHOS-ATP and trend-increased glycolysis-ATP production on days 4 and 7 compared with day 0, which contrasted with the stable levels in OAT-H. FA supplementation in culture-medium triggered adipogenesis in PFs both from OAT-H and OAT-GO, which was substantially enhanced by 1-mM GDP reaching 7% to 18% of ADM adipogenesis. The FA-uptake–driven adipogenesis was diminished by oligomycin-A but unaffected by treatment with ADP or AICAR. Furthermore, we observed a significant positive correlation between FA-uptake–driven adipogenesis by GDP and the ratios of OXPHOS-ATP/glycolysis-ATP through adipogenesis of PFs from OAT-GO. Conclusion Our study confirmed that FA uptake can drive OAT adipogenesis and revealed a fundamental role for mitochondria-OXPHOS in GO development, which provides potential for therapeutic interventions. [ABSTRACT FROM AUTHOR]

Genetic mutations in thyrotropin receptors on the thyroid gland may have a role in both hyperthyroid and hypothyroid disorders. Thyrotropin is a hormone that regulates the thyroid gland in the neck. Mutations in the receptor gene may cause 48-70% of thyroid adenomas, which are benign tumors of thyroid tissue that independently produce hormones. They also have been found in hereditary nonimmune hyperthyroidism, and in autoimmune conditions where antibodies attack or stimulate the receptors . Receptor mutations can cause low thyroid levels by making the gland resistant to thyrotropin stimulation.