Role Of Immune Cell In Thyroid Diseases

Backgrounds:The immune system is crucial for maintain self-defense hemostasis with the ability to identify self and non-self.In thyroid diseases,the immune system identifies TSHR as non-self component and produces autoantibodies,leading to the occurrence of Graves'disease.On the other hand,the immune system may participate in the progression of thyroid carcinoma when immunocyte is unable to effectively clear neoplasms.Objectives:This study was designed to reveal the clonal characteristics of B lymphocyte repertoire in patients with GD to facilitate better understanding of its pathogenesis.Roles of tumor associated macrophages(TAMs)remained unclear in follicular thyroid carcinoma.Here we analyzed the differences between TAMs in FTC and those in FA.Methods:Using high-throughput sequencing of Ig genes,we analyzed the repertoire of circulating B lymphocytes in 20 patients with GD longitudinally,and 20 age-and gender-matched healthy controls.We first analyzed the density of TAMs by CD68 immunostaining in 59 histologically confirmed FTCs and 47 FAs.Cytokines produced by FTC and FA were profiled using antibody array,and validated by quantitative PCR.Chemotaxis of monocyte THP-1 was induced by condition medium of FTC cell lines(FTC133 and WR082-1)with and without anti-CCL 15 neutralizing antibody.Finally,we analyzed CCL15 protein level in FTC and FA by immunohistochemistry.Results:Compared with healthy controls,GD patients showed 1)a preferable usage of IGHV3 gene,espically over-representation of the IGHV3-7,IGHV3-11,IGHV3-30 gene segments;2)a significant decreased relative IgG abundance,which was accompanied with increased IgM abundance in untreated GD;3)a significant reduction of clonal diversity,which shows a correlation with the level of TRAb;The average density of CD68 positive cells was 9.5±5.4/field in FTC,significantly higher than that in FA(4.9±3.4/field,p<0.001).Subsequently profiling showed that CCL15 was the most abundant chemokine in FTC compared with FA.CCL15 mRNA in FTC was 51.4-folds of that in FA.CM of FTC cell lines induced THP-1 cell chemotaxis by 33%?77%,and anti-CCL15 neutralizing antibody reduced THP-1 cell migration in a dose-dependent manner.Moreover,we observed positive CCL15 immunostaining in 67.8%of FTCs compared with 23.4%of FAs.Conclusions:Our data suggested that GD is a complex autoimmune disease process with evidence of B lymphocyte clonal gains and losses,and IGHV usage bias.This new insight into the pathogenesis of GD opens up the prospect of studying disease relevant B cells to better diagnose and treat this devastating disease.Our study suggested FTC might induce TAMs infiltration by producing CCL15.Measurement of TAMs and CCL15 in follicular thyroid lesions may be applied clinically to differentiate FTC from FA pre-operation.