The changes in peripheral blood Th17 and Treg ratios in Hashimoto's thyroiditis are accompanied by differential PD-1/PD-L1 expression.

Objective: The aim of this study was to analyze the percentages of T helper 17 cells (Th17s) and T regulatory cells (Tregs) in autoimmune Hashimoto's thyroiditis (HT), and the expression of the checkpoint molecules programmed death receptor 1/programmed death ligand 1 (PD-1/PD-L1) on these cells. Methods: This is a case-control study involving 53 initially diagnosed HT patients (HT group) and 21 normal controls (NC group). The peripheral blood mononuclear cells from the individuals of the two groups were isolated and restimulated ex vivo; the percentage of Th17s, Tregs, PD-1+ Th17s, PD-L1+ Th17s, PD-1+ Tregs, and PD-L1+ Tregs was assessed by flow cytometric analysis. Results: (1) The percentage of Th17s in the peripheral blood of the HT group was significantly higher than that of the NC group [(6.38 ± 1.32)% versus (3.12 ± 0.66)%; t = 14.110, P < 0.001], while the percentage of peripheral blood Tregs was significantly lower [(3.82 ± 1.48)% versus (5.61 ± 1.60)%; t = -4.599, P < 0.001]. (2) HT patients' Th17s expressed PD-1 at a significantly lower frequency than their counterparts in the NC [(6.46 ± 2.77)% versus (18.51 ± 3.96)%; t = -14.842, P < 0.001], while no difference was observed for PD-L1 between the two groups. (3) In contrast, both PD-1 and PD-L1 were expressed at significantly higher frequency on HT patients' Tregs than on NC [respectively: (17.01 ± 3.04)% versus (10.23 ± 2.77)%; t = 8.850, P < 0.001 for PD-1; (16.60 ± 9.58)% versus (11.36 ± 10.14)%; t = 2.089, P < 0.005, for PD-L1]. Conclusion: (1) The increased percentage of Th17s and decreased percentage of PD-1+ Th17s in the HT group suggest that a loss of control on Th17 activity through the checkpoint inhibitory axis PD-1/PD-L1 may participate in disease pathogenesis. (2) While the decreased percentage of Tregs in HT patients may explain a lack of regulatory functions able to prevent the autoimmune destruction of the thyroid, the significance of the increased frequency of Tregs expressing PD-1 and PD-L1, previously reported to boost Tregs differentiation, remains to be established. Elucidating this apparent contradiction may reveal important mechanisms underlying HT pathogenesis.

Correlation between single nucleotide polymorphism of FCRL-3 gene and Graves' disease in Han population of northern Anhui province, China.

OBJECTIVE: The frequency distribution of A/G genotype at position-169 in promoter of FCRL3 gene (Fc receptor-like 3) was identified in Han population of northern Anhui Province. The correlation between single nucleotide polymorphism (SNP) at this site and genetic susceptibility of Graves disease (GD) was discussed. How the genotype at this position correlated to age, gender, severity of goiter, presence or absence of exophthalmos, levels of thyrotrophin receptor antibody (TRab), thyroid peroxidase antibody (TpoAb) and anti-thyroglobulin antibody (TgAb) and thyroid function was analyzed in details. METHOD: Peripheral venous blood was collected for DNA extraction. SNP at position-169 in the promoter of FCRL3 gene was determined by using PCR-RELP among 180 GD cases and 146 normal subjects. Thyroid function tests and antibody detection were performed. RESULTS: The frequency of GG genotype of position-169 in promoter of FCRL3 gene was higher in GD group than in control group. The frequency was 28.9% and 13.8%, respectively, showing significant differences in intergroup comparison (χ(2)=6.618, P=0.046). The G allele frequency of GD group and control group was 49.4% and 40.4%, respectively, also showing significant differences between the groups (χ(2)=5.308, P=0.021). GD cases with AA, AG and GG genotypes at position-169 in FCRL3 promoter had significant differences in serum level of TRAb (χ(2)=7.319, P=0.026). However, no significant differences in gender, severity of goiter, TpoAb and TgAb level, presence or absence of exophthalmos and thyroid function (FT3, FT4, TSH) were found between the three genotypes (P>0.05). CONCLUSION: A/G SNP at position-169 in promoter of FCRL3 gene was correlated with susceptibility to GD among Han population in northern Anhui Province. G allele may contribute to the susceptibility to GD and correlate to positive TRAb result in thyroid diseases, but not to age of onset, gender, presence or absence of exophthalmos, thyroid function, TpoAb and TgAb level or severity of goiter.