Search

A balance between pro-inflammatory decidual CD4 + T cells and FOXP3 + regulatory T cells ( FOXP3 + Tregs) is important for maintaining fetomaternal tolerance. Using single-cell RNA-sequencing and T cell receptor repertoire analysis, we determined that diversity and clonality of decidual CD4 + T cell subsets depend on gestational age. Th1/Th2 intermediate and Th1 subsets of CD4 + T cells were clonally expanded in both early and late gestation, whereas FOXP3 + Tregs were clonally expanded in late gestation. Th1/Th2 intermediate and FOXP3 + Treg subsets showed altered gene expression in preeclampsia (PE) compared to healthy late gestation. The Th1/Th2 intermediate subset exhibited elevated levels of cytotoxicity-related gene expression in PE. Moreover, increased Treg exhaustion was observed in the PE group, and FOXP3 + Treg subcluster analysis revealed that the effector Treg like subset drove the Treg exhaustion signatures in PE. The Th1/Th2 intermediate and effector Treg like subsets are possible inflammation-driving subsets in PE., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Tsuda, Shichino, Tilburgs, Shima, Morita, Yamaki-Ushijima, Roskin, Tomura, Sameshima, Saito and Nakashima.)

Dendritic cells (DCs) are essential for successful embryo implantation. However, the properties of uterine DCs (uDCs) during the implantation period are not well characterized. In this study, we investigated the dynamic changes in the uDC phenotypes during the period between coitus and implantation. In virgin mice, we evaluated the expressions of CD103 and XCR1, this is the first report to demonstrate uDCs expressing CD103 in XCR1 + cDC1s and XCR1 + cDC2s. On day 0.5 post coitus (pc), the number of uterine CD11c + CD103 - MHC classII high CD86 high -mature DCs rapidly increased and then decreased to non-pregnancy levels on days 1.5 and 2.5 pc. On day 3.5 pc just before implantation, the number of CD11c + CD103 + MHC class II dim CD86 dim -immature DCs increased in the uterus. The increase in mature uDCs on day 1.5 pc was observed in both allogeneic- and syngeneic mating, suggesting that sexual intercourse, or semen, play a role in this process. Meanwhile, the increase in immature uDCs on day 3.5 pc was only observed in allogeneic mating, suggesting that allo-antigens in the semen contribute to this process. Next, to understand the turnover and migration of uDCs, we monitored DC movement in the uterus and uterine draining lymph nodes (dLNs) using photoconvertible protein Kikume Green Red (KikGR) mice. On day 0.5 pc, uDCs were composed of equal numbers of remaining DCs and migratory DCs. However, on day 3.5 pc, uDCs were primarily composed of migratory DCs, suggesting that most of the uDCs migrate from the periphery just before implantation. Finally, we studied the expression of PD-L2-which induces immunoregulation-on DCs. On day 3.5 pc, PD-L2 was expressed on CD103 + -mature and CD103 - -mature DCs in the uterus. However, PD-L2 expression on CD103 - -immature DCs and CD103 + -immature DCs was very low. Furthermore, both remaining and migratory DCs in the uterus and uterus-derived-DCs in the dLNs on day 3.5 pc highly expressed PD-L2 on their surface. Therefore, our study findings provide a better understanding of the dynamic changes occurring in uterine DCs and dLNs in preparation for implantation following allogeneic- and syngeneic mating., (Copyright © 2020 Yasuda, Shima, Moriya, Ikebuchi, Kusumoto, Ushijima, Nakashima, Tomura and Saito.)

Regulatory T cells (Tregs) migrate between lymphoid and peripheral tissues for maintaining immune homeostasis. Tissue-specific function and functional heterogeneity of Tregs have been suggested, however, correlation between them and inter-tissue movement remain unknown. We used a contact hypersensitivity model of mice expressing a photoconvertible protein for tracking migratory cells. After marking cells in skin, we purified Tregs exhibiting a different migration pattern [Tregs recruiting to or remaining in the skin and emigrating from the skin to draining lymph nodes (dLNs) within half a day] and examined single-cell gene and protein expression profiles. Correlation and unsupervised clustering analyses revealed that Tregs in both skin and dLNs comprised two subpopulations, one highly expressing Nrp1 with variable CD25, Granzyme B, and/or CTLA-4 expression and another with 3 subsets strongly expressing CD25, Granzyme B, or CTLA-4 together with CD39. Characteristic subsets of Tregs remaining in the skin displayed higher CD25 and CD39 expression and lower Granzyme B and CTLA-4 expression compared with Tregs migrating to the skin. In addition, CCR5 expression in Tregs in skin was positively and negatively correlated with CD39 and Nrp-1 expression, respectively. To assess the predictive value of these data for immunotherapy, we blocked CCR5 signaling and found modest downregulation of CD39 and modest upregulation of Nrp1 expression in skin Tregs. Our data reveal a high functional diversity of Tregs in skin that is strongly related to trafficking behavior, particularly skin retention. Modulation of tissue-specific trafficking and function is a promising clinical strategy against autoimmune, infectious, and neoplastic diseases., Significance Statement: Regulatory T cells (Tregs) are essential for maintaining immune homeostasis. To reveal tissue-specific immunoinhibitory functions and inter-tissue movement correlation based on Treg functional heterogeneity, we examined single-cell gene and protein expression profiles of Tregs recruited to, remaining in, or emigrating from the contact hypersensitivity-induced inflamed skin. Tregs in skin were composed of several subpopulations; one with high Nrp1 expression and another with 3 subsets strongly expressing CD25, Granzyme B, or CTLA-4 together with CD39. Tregs remaining in skin displayed highCD25, CD39, and CCR5 expression, and CCR5 signaling blockade downregulated CD39. A high Treg functional diversity in skin is strongly related to trafficking behavior. Tissue-specific trafficking and functional modulation are a promising clinical strategy against autoimmune, infectious, and neoplastic diseases.

Initiation of adaptive immunity involves distinct migratory cell populations coming together in a highly dynamic and spatially organized process. However, we lack a detailed spatiotemporal map of these events due to our inability to track the fate of cells between anatomically distinct locations or functionally identify cell populations as migratory. We used photo-convertible transgenic mice (Kaede) to spatiotemporally track the fate and composition of the cell populations that leave the site of priming and enter the draining lymph node to initiate immunity. We show that following skin priming, the lymph node migratory population is principally composed of cells recruited to the site of priming, with a minor contribution from tissue resident cells. In combination with the YAe/Eα system, we also show that the majority of cells presenting antigen are CD103 + CD11b + dendritic cells that were recruited to the site of priming during the inflammatory response. This population has previously only been described in relation to mucosal tissues. Comprehensive phenotypic profiling of the cells migrating from the skin to the draining lymph node by mass cytometry revealed that in addition to dendritic cells, the migratory population also included CD4 + and CD8 + T cells, B cells, and neutrophils. Taking our complex spatiotemporal data set, we then generated a model of cell migration that quantifies and describes the dynamics of arrival, departure, and residence times of cells at the site of priming and in the draining lymph node throughout the time-course of the initiation of adaptive immunity. In addition, we have identified the mean migration time of migratory dendritic cells as they travel from the site of priming to the draining lymph node. These findings represent an unprecedented, detailed and quantitative map of cell dynamics and phenotypes during immunization, identifying where, when and which cells to target for immunomodulation in autoimmunity and vaccination strategies.

Dendritic cell activation of CD4 T cells in the lymph node draining a site of infection or vaccination is widely considered the central event in initiating adaptive immunity. The accepted dogma is that this occurs by stimulating local activation and antigen acquisition by dendritic cells, with subsequent lymph node migration, however the generalizability of this mechanism is unclear. Here we show that in some circumstances antigen can bypass the injection site inflammatory response, draining freely and rapidly to the lymph nodes where it interacts with subcapsular sinus (SCS) macrophages resulting in their death. Debris from these dying SCS macrophages is internalized by monocytes recruited from the circulation. This coordinated response leads to antigen presentation by monocytes and interactions with naïve CD4 T cells that can drive the initiation of T cell and B cell responses. These studies demonstrate an entirely novel pathway leading to initiation of adaptive immune responses in vivo .