Proposed Role of RGS1 in Modulating IL-1β-IL-1R1-IRAK4-TAK1 Signaling in Endometriotic Stromal Cells

The pathology of endometriosis is associated with various inflammatory cytokines, including IL-1β, and recent studies have shown that spheroid cell cultures can be used to investigate the mechanisms of endometriosis-associated inflammation and cell proliferation more effectively than that of monolayer cell cultures. However, the detailed role of the IL-1β signaling pathway in endometriotic stromal cells in spheroid cell cultures remains unclear. This study investigated the role of the IL-1β pathway in the pathogenesis of endometriosis in spheroid cell cultures derived from ovarian endometrioma stromal cells (OESCs) and normal endometrial stromal cells (NESCs). Specimens were collected from 22 patients with and 11 patients without endometriosis. IL-6/IL-8 protein production was evaluated by ELISA, gene expression by real-time PCR, cell proliferation by WST-8 assay, and RGS1 expression by immunohistochemical staining. Spheroid OESCs showed elevated IL-6/IL-8 production and increased expression of inflammation-related genes compared with monolayer cell cultures. IL-1β promoted the proliferation of spheroid OESCs and upregulated endometriosis-associated gene expression, but did not promote the proliferation of spheroid NESCs. Spheroid OESCs also showed increased levels of IL-1R1 and NLRP3 mRNA. IRAK4, TAK1, and RGS inhibitors suppressed cell proliferation and IL-6/IL-8 production in spheroid OESCs treated with IL-1β. Additionally, RGS1 was highly expressed in OESCs. The IL-1β pathway is crucial for OESCs proliferation and IL-6/IL-8 production in spheroid culture. Thus, RGS1, IRAK4, and TAK1 may serve as novel therapeutic targets for endometriosis. Similar content being viewed by others Data Availability All data will be shared on reasonable request to the corresponding author.

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We thank Ms. Makoto Kazui and Ms. Naoko Matsunaga for their technical support, and Dr. Gerald E. Smyth, Nippon Shinyaku Co., Ltd., for English language revision. This study was funded in part by the Ministry of Education, Culture, Sports, Science and Technology (Japan) through Grants-in-Aid for Scientific Research (21K09523, 23K15819). Author information Authors and Affiliations Contributions 1. Yota Tsuzuki: Conceptualization (equal); Writing – Original Draft Preparation (lead); Investigation (lead). 2. Yosuke Tarumi: Project Administration (supporting); Resources (equal). 3. Toshiyuki Minami: Conceptualization (equal); Writing – Original Draft Preparation (supporting). 4. Fumitake Ito: Resources (equal). 5. Koki Shimura: Resources (equal). 6. Akihisa Katayama: Resources (equal). 7. Yuko Izumi: Resources (equal). 8. Jo Kitawaki: Project Administration (equal). 9. Taisuke Mori: Project Administration (lead); Supervision (lead). Corresponding author Ethics declarations Ethics Approval This study was performed in line with the principles of the Declaration of Helsinki. Approval was granted by the Institutional Review Board of the Kyoto Prefectural University of Medicine (approval no., ERB-C-2410). Consent to Participate All participants provided written informed consent before participation. Consent to Publication All agreed to publish this article. Competing interests Yota Tsuzuki and Toshiyuki Minami are employed by Nippon Shinyaku Co., Ltd. The remaining authors declare that they have nothing to disclose. Additional information Publisher's Note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. Rights and permissions Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law. About this article Cite this article Tsuzuki, Y., Tarumi, Y., Minami, T. et al. Proposed Role of RGS1 in Modulating IL-1β-IL-1R1-IRAK4-TAK1 Signaling in Endometriotic Stromal Cells. Reprod. Sci. 33, 346–357 (2026). https://doi.org/10.1007/s43032-025-02014-2 Received: Accepted: Published: Version of record: Issue date: DOI: https://doi.org/10.1007/s43032-025-02014-2