The STAT signaling profile at the single cell level reveals novel insights in the association of FOXP3+ T regulatory cells with recurrent spontaneous abortions before and after lymphocyte immunotherapy.

Foxp3+ T regulatory cell (Tregs) are central in the pathobiology of recurrent spontaneous abortions (RSA). Signal transducer and activator of transcription (STAT) proteins instruct Treg differentiation and polarization, but the STAT signaling architecture of Tregs in RSA and its modifications by lymphocyte immunotherapy (LIT) are yet unknown. By using single-cell phospho-specific flow cytometry we show that the STAT signaling biosignature of Tregs in women with RSA was characterized by marked downregulation of the IFNα/pSTAT1&5, IL-6/pSTAT1&3 and IL-2/pSTAT5 signaling nodes compared to age-matched fertile females. LIT partially restored all of these signaling axes in Tregs only in women who achieved pregnancy after treatment. Both the pretreatment biosignature of Tregs and its modulations by LIT were associated with therapeutic success. We conclude that STAT signaling pathways in Tregs are actively involved in the pathophysiology of RSA and may serve as a predictive tool for selecting patients who may benefit from LIT.
(Copyright © 2019 Elsevier Inc. All rights reserved.)