The Role of Follicular Regulatory T Cells/Follicular Helper T Cells in Primary Immune Thrombocytopenia.

Introduction: Immune thrombocytopenia (ITP) is an autoimmune disease characterized by thrombocytopenia. Herein, we sought to identify potential immune-related therapeutic targets in ITP.

Methods: The differentially expressed genes (DEGs) between ITP patients and controls in GSE43177 and PRJNA299534 were analyzed. The intersections of the two DEG groups were screened as common genes, and enrichment analysis was performed. Additionally, differential analysis of immune cell levels between ITP and controls was performed. Changes in the proportions of T follicular helper (Tfh) and follicular regulatory T (Tfr) cells in peripheral blood samples from ITP patients, ITP patients responding to therapy, and healthy controls were identified. The expression changes in B-cell lymphoma (Bcl)-6 and interleukin (IL)-21 were further evaluated.

Results: A total of 76 common genes were identified, and enrichment analysis found that these genes were mainly associated with neutrophil-mediated immunity, the MAPK signaling pathway, and the FOXO signaling pathway. Furthermore, we found different levels of Tfh cells in patients with ITP and controls. The level of Tfh cells in the peripheral blood is significantly increased in ITP patients and declines after responding to therapy. The Tfr/Tfh ratio was reduced in ITP patients and increased after responding to therapy. IL-21 and Bcl-6 were more highly expressed in ITP patients than in controls.

Conclusion: We identified abnormally expressed genes in ITP related to immune-related biological functions. We further identified the changes in Tfh and Tfr cells during ITP treatment. This provides a rationale for immunotherapy in ITP patients.