Decidual stromal cells: fibroblasts specialized in immunoregulation during pregnancy Llorca, Tatiana Ruiz Magaña, María José Abadía Molina, Ana Clara Ruiz Ruiz, María Carmen García Olivares, Enrique Fernando Decidual stromal cells Endometrial stromal cells Tertiary lymphoid structures We thank K. Shashok for editing the use of English in this manuscript. Financial support was provided by Proyectos de I+D+I through the Programa Operativo Feder Andalucía (Grant B-CTS-228-UGR20). Decidual stromal cells (DSCs) are involved in immunoregulatory mechanisms that prevent fetal rejection by the mammalian maternal immune system. Recent studies using single-cell RNA sequencing demonstrated the existence of different types of human and mouse DSCs, highlighting corresponding differentiation (decidualization) pathways, and suggesting their involvement in the immune response during normal and pathological pregnancy. DSCs may be considered tissue-specialized fibroblasts because both DSCs and fibroblasts share phenotypic and functional similarities in immunologically challenged tissues, especially in terms of their immune functions. Indeed, fibroblasts can setup, support, and suppress immune responses and these functions are also performed by DSCs. Moreover, fibroblasts and DSCs can induce ectopic foci as tertiary lymphoid structures (TLSs), and endometriosis, respectively. Thus, understanding DSC immunoregulatory functions is of timely relevance. 2026-01-13T07:50:57Z 2026-01-13T07:50:57Z 2025-02 journal article Publisher version: T Llorca, MJ Ruiz-Magaña, AC Abadía, C Ruiz-Ruiz, EG Olivares. Decidual stromal cells: fibroblasts specialized in immunoregulation during pregnancy. Trends Immunol. 2025, 46:138-152. doi: 10.1016/j.it.2024.12.007. 1471-4906 1471-4981 https://hdl.handle.net/10481/109580 10.1016/j.it.2024.12.007 eng http://creativecommons.org/licenses/by-nc-nd/3.0/ embargoed access Creative Commons Attribution-NonCommercial-NoDerivs 3.0 License Cell Press