Abstract: Objective To explore the genes affecting the dysfunction of dendritic cells in patients with primary immune thrombocytopenia(ITP), and to seek a new therapeutic approach for ITP. Methods A total of 8 ITP patients and 8 healthy controls were enrolled. Peripheral mononuclear cells were isolated and induced to differentiate into monocyte derived dendritic cells(moDCs)in vitro. The moDCs samples from 3 ITP patients and 3 healthy controls were selected respectively, then transcriptome sequencing was performed using Illumina Hiseq platform, and bioinformatics analysis was completed. The remaining moDCs samples were divided into control group, ITP group and ITP+rapamycin group. The activation of mammalian rapamycin target protein complex 1(mTORC1)signal pathway was detected with Western blotting, the expressions of surface molecules were detected with flow cytometry, and the cytokine secretions were detected with enzyme-linked immunosorbent assay(ELISA). Results Differential gene analysis showed that compared with the healthy controls, ITP patients had 161 significantly up-regulated genes and 320 significantly down-regulated genes(P<0.05). The differential genes were mainly concentrated in biological processes such as T cell differentiation, T cell costimulation, T cell activation and T cell receptor signaling pathway. Gene set enrichment analysis(GSEA)showed that the activity of mTORC1 signal pathway in moDCs of ITP patients was enhanced. Further validation found that the expression of phosphorylated mTOR and mTORC1 activation marker phosphorylated ribosomal protein S6 kinase(S6K)in moDCs of ITP patients were increased. The expressions of moDCs costimulatory molecules CD80 and CD86, and pro-inflammatory factors interleukin(IL)-6 and IL-12 were increased in ITP patients, while the expressions of IL-10 and transforming growth factor-β(TGF-β)were decreased. The mTORC1 inhibitor rapamycin inhibited the expressions of CD80, CD86, IL-6 and IL-12. Rapamycin upregulated the expression of IL-10, but did not affect the expression of TGF-β. Conclusion The mTORC1 signaling pathway is highly activated in moDCs of ITP patients, and the use of rapamycin can improve the immunomodulatory ability of moDCs. Therefore, mTORC1 signaling pathway may be a new target for regulating moDCs dysfunction in ITP patients.

Key words: Primary immune thrombocytopenia, Dendritic cells, Transcriptome sequencing, mTORC1 signaling pathway, Rapamycin