Glucocorticoid receptor in T cells mediates protection PNAS PLUS from autoimmunity in pregnancy Jan Broder Englera, Nina Kursawea, María Emilia Solanob, Kostas Patasa, Sabine Wehrmanna, Nina Heckmanna, Fred Lühderc, Holger M. Reichardtd, Petra Clara Arckb, Stefan M. Golda,e, and Manuel A. Friesea,1 aInstitut für Neuroimmunologie und Multiple Sklerose, Zentrum für Molekulare Neurobiologie Hamburg, Universitätsklinikum Hamburg-Eppendorf, 20251 Hamburg, Germany; bExperimentelle Feto-Maternale Medizin, Klinik für Geburtshilfe und Pränatalmedizin, Universitätsklinikum Hamburg-Eppendorf, 20251 Hamburg, Germany; cInstitut für Neuroimmunologie und Institut für Multiple Sklerose Forschung, Universitätsmedizin Göttingen, 37073 Goettingen, Germany; dInstitut für Zelluläre und Molekulare Immunologie, Universitätsmedizin Göttingen, 37075 Goettingen, Germany; and eKlinik für Psychiatrie und Psychotherapie, Campus Benjamin Franklin, Charité Universitätsmedizin, 12203 Berlin, Germany Edited by Philippa Marrack, Howard Hughes Medical Institute, National Jewish Health, Denver, CO, and approved December 6, 2016 (received for review October 17, 2016) Pregnancy is one of the strongest inducers of immunological toler- immunological tolerance (18, 22). Depletion of Tregs results in fetal ance. Disease activity of many autoimmune diseases including mul- loss (23). Pregnancy-related hormonal signals, including estrogens tiple sclerosis (MS) is temporarily suppressed by pregnancy, but little and progesterone (1, 24, 25), appear to support Treg proportion is known about the underlying molecular mechanisms. Here, we in- and function, although their exact mode of action remains in- vestigated the endocrine regulation of conventional and regulatory completely understood. T cells (Tregs) during reproduction. In vitro, we found the pregnancy In the context of autoimmunity, Tregs are essential in suppressing hormone progesterone to robustly increase Treg frequencies via autoreactive responses. Foxp3 deficiency results in generalized au- promiscuous binding to the glucocorticoid receptor (GR) in T cells. In toimmune inflammation evident in scurfy mice (2–4, 26) and in vivo, T-cell–specific GR deletion in pregnant animals undergoing ex- patients suffering from immunodysregulation polyendocrinopathy perimental autoimmune encephalomyelitis (EAE), the animal model enteropathy X-linked syndrome (IPEX) (5, 27). Beyond that, of MS, resulted in a reduced Treg increase and a selective loss of quantitative or functional Treg impairment has been described in a pregnancy-induced protection, whereas reproductive success was un- number of autoimmune diseases, including systemic lupus eryth- affected. Our data imply that steroid hormones can shift the immu- ematosus (6, 7, 28, 29), rheumatoid arthritis (8, 30, 31), and type I nological balance in favor of Tregs via differential engagement of the diabetes (9, 10, 32). In MS, Tregs were reported to possess di- GR in T cells. This newly defined mechanism confers protection from minished suppressive potential (11, 33, 34) and decreased expres- autoimmunity during pregnancy and represents a potential target for future therapy. sion of Foxp3 and immunosuppressive cytotoxic T lymphocyte antigen 4 (CTLA-4) (12, 35–37). multiple sclerosis | autoimmunity | pregnancy | Treg | steroid hormones However, it is still unknown which pregnancy-related changes account for the enhanced control of autoreactive responses. Here, we sought to unravel the molecular mechanisms that confer the eproduction is fundamental to the maintenance and evolu- beneficial effect of pregnancy on autoimmunity. By studying the tion of species. To ensure successful pregnancy, mothers R impact of pregnancy and pregnancy hormones on T-cell subsets have to establish robust immunological tolerance toward the semi- including Tregs, we provide evidence that differential sensitivity to allogeneic conceptus providing a secure niche for fetal development. Multiple mechanisms have evolved to prevent fetus-directed immune glucocorticoid receptor (GR) activity is a hitherto unrecognized responses and alloreactive infiltration of the fetomaternal interface (1). These include creating a privileged local microenvironment that Significance hampers T-cell priming and infiltration (2–4) but also imply global modulation of the immune system by pregnancy hormones and the Reproduction in placental mammals relies on potent control of shedding of fetal antigen into the mothers circulation (5). the mother’s immune system to not attack the developing fetus. Intriguingly, pregnancy is also well known to suppress the in- As a bystander effect, pregnancy also potently suppresses the flammatory activity of a number of cell-mediated autoimmune dis- activity of the autoimmune disease multiple sclerosis (MS). Here, eases, including rheumatoid arthritis (6, 7), autoimmune hepatitis we report that T cells are able to directly sense progesterone via (8), and multiple sclerosis (MS) (9, 10). However, this beneficial their glucocorticoid receptor (GR), resulting in an enrichment of effect is limited to the period of gestation and usually followed by a regulatory T cells (Tregs). By using an MS animal model, we found rebound of disease activity postpartum. In the case of MS, third that the presence of the GR in T cells is essential to increase Tregs trimester pregnancy leads to a remarkable reduction of the MS and confer the protective effect of pregnancy, but not for relapse rate (11), which exceeds the effects of most currently avail- maintaining the pregnancy itself. Better understanding of this able disease-modifying drugs. Similarly, pregnancy as well as treat- tolerogenic pathway might yield more specific therapeutic means ment with pregnancy hormones protect rodents from experimental to steer the immunological balance in transplantation, cancer, autoimmune encephalomyelitis (EAE), a widely used animal model and autoimmunity. of MS (12) in both SJL/J and C57BL/6 mice (13–16), underpinning an interaction between pregnancy-related immune and endocrine Author contributions: J.B.E., S.M.G., and M.A.F. designed research; J.B.E., N.K., M.E.S., K.P., S.W., and N.H. performed research; F.L., H.M.R., and P.C.A. contributed new adaptations and central nervous system (CNS) autoimmunity (17). reagents/analytic tools; J.B.E., N.K., P.C.A., and M.A.F. analyzed data; and J.B.E. and The sensitive balance between conventional effector T cells M.A.F. wrote the paper. (Tcons) and regulatory T cells (Tregs) has transpired as a common The authors declare no conflict of interest. theme that connects reproductive biology and autoimmunity on a This article is a PNAS Direct Submission. – mechanistic level (18 21). Tregs are characterized by the tran- Freely available online through the PNAS open access option. scription factor forkhead box P3 (Foxp3) and effectively control 1To whom correspondence should be addressed. Email: [email protected] effector responses mounted by Tcons in response to antigen-specific hamburg.de. activation. In the context of pregnancy, Tregs were shown to expand This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10. INFLAMMATION IMMUNOLOGY AND to safeguard against fetal rejection by establishing antigen-directed 1073/pnas.1617115114/-/DCSupplemental. www.pnas.org/cgi/doi/10.1073/pnas.1617115114 PNAS | Published online January 3, 2017 | E181–E190 Downloaded by guest on October 5, 2021 mechanism shaping the T-cell compartment. By targeted GR antigen and the systemic challenge with fetal antigen following pla- deletion in T cells, we show a selective disruption of pregnancy- cental perfusion, respectively. In line with this observation, the first induced protection from autoimmunity. expansion was limited to the local paraaortic lymph nodes, whereas the second was also detectable in regional inguinal lymph nodes and Results systemically in the spleen (Fig. 1E). Additionally, late pregnancy Treg Dynamics During Pregnancy. We first characterized the relative Tregs consistently showed increased expression of the immunosup- abundance and phenotype of Tcons and Tregs throughout preg- pressive molecule CTLA-4 in all assessed organs, rendering them nancy and postpartum time points (Fig. 1A). Because the presence potentially more effective in controlling effector responses (Fig. 1E). + − of fetuses that genetically differ from the mother is a prerequisite CD4 Foxp3 conventional T cells (Tcons) showed only one pro- of robust induction of immune tolerance (13–15,18),weperformed liferative burst in early pregnancy (E2.5) that was accompanied by allogeneic matings of C57BL/6 females with BALB/c males. We increased CTLA-4 expression, whereas their proliferative activity analyzed cells from paraaortic lymph nodes (LNs), inguinal lymph appeared to be tightly controlled at later time points (Fig. S1). nodes, and spleen to get insight into local, regional, and systemic Together, the Treg response commenced in early gestation changes, respectively (Fig. 1B). The acquired data indicated that with a local proliferative burst and generalized toward systemic Treg expansion was most pronounced in the paraaortic lymph nodes + + compartments in late gestation. Late gestational Tregs showed that drain the fetomaternal interface. Frequencies of CD4 Foxp3 increased expression of CTLA-4, potentially supporting their Tregs started to increase from middle to late pregnancy (embryonic suppressive function. days, E10.5–E18.5) and stayed at elevated levels as long as post- partum day