Deregulation of the endometrial stromal cell secretome precedes embryo implantation failure

STUDY QUESTION Is implantation failure following ART associated with a perturbed decidual response in endometrial stromal cells (EnSCs)? SUMMARY ANSWER Dynamic changes in the secretome of decidualizing EnSCs underpin the transition of a hostile to a supportive endometrial microenvironment for embryo implantation; perturbation in this transitional pathway prior to ART is associated with implantation failure. WHAT IS KNOWN ALREADY Implantation is the rate-limiting step in ART, although the contribution of an aberrant endometrial microenvironment in IVF failure remains ill defined. STUDY DESIGN, SIZE, DURATION In vitro characterization of the temporal changes in the decidual response of primary EnSCs isolated prior to a successful or failed ART cycle. An analysis of embryo responses to secreted cues from undifferentiated and decidualizing EnSCs was performed. The primary clinical outcome of the study was a positive urinary pregnancy test 14 days after embryo transfer. PARTICIPANTS/MATERIALS, SETTING, METHODS Primary EnSCs were isolated from endometrial biopsies obtained prior to IVF treatment and cryopreserved. EnSCs from 10 pregnant and 10 non-pregnant patients were then thawed, expanded in culture, subjected to clonogenic assays, and decidualized for either 2 or 8 days. Transcript levels of decidual marker gene [prolactin (PRL), insulin-like growth factor binding protein 1 (IGFBP1) and 11β-hydroxysteroid dehydrogenase (HSD11B1)] were analysed using real-time quantitative PCR and temporal secretome changes of 45 cytokines, chemokines and growth factors were measured by multiplex suspension bead immunoassay. The impact of the EnSC secretome on human blastocyst development was scored morphologically; and embryo secretions in response to EnSC cues analyzed by multiplex suspension bead immunoassay. MAIN RESULTS AND THE ROLE OF CHANCE Clonogenicity and induction of decidual marker genes were comparable between EnSC cultures from pregnant and non-pregnant group groups (P > 0.05). Analysis of 23 secreted factors revealed that successful implantation was associated with co-ordinated secretome changes in decidualizing EnSCs, which were most pronounced on Day 2 of differentiation: 17 differentially secreted proteins on Day 2 of decidualization relative to undifferentiated (Day 0) EnSCs (P 0.05)

The role and uses of antibodies in COVID-19 infections: a living review

Coronavirus disease 2019 has generated a rapidly evolving field of research, with the global scientific community striving for solutions to the current pandemic. Characterizing humoral responses towards SARS-CoV-2, as well as closely related strains, will help determine whether antibodies are central to infection control, and aid the design of therapeutics and vaccine candidates. This review outlines the major aspects of SARS-CoV-2-specific antibody research to date, with a focus on the various prophylactic and therapeutic uses of antibodies to alleviate disease in addition to the potential of cross-reactive therapies and the implications of long-term immunity

T cell phenotypes in COVID-19 - a living review

COVID-19 is characterized by profound lymphopenia in the peripheral blood, and the remaining T cells display altered phenotypes, characterized by a spectrum of activation and exhaustion. However, antigen-specific T cell responses are emerging as a crucial mechanism for both clearance of the virus and as the most likely route to long-lasting immune memory that would protect against re-infection. Therefore, T cell responses are also of considerable interest in vaccine development. Furthermore, persistent alterations in T cell subset composition and function post-infection have important implications for patients’ long-term immune function. In this review, we examine T cell phenotypes, including those of innate T cells, in both peripheral blood and lungs, and consider how key markers of activation and exhaustion correlate with, and may be able to predict, disease severity. We focus on SARS-CoV-2-specific T cells to elucidate markers that may indicate formation of antigen-specific T cell memory. We also examine peripheral T cell phenotypes in recovery and the likelihood of long-lasting immune disruption. Finally, we discuss T cell phenotypes in the lung as important drivers of both virus clearance and tissue damage. As our knowledge of the adaptive immune response to COVID-19 rapidly evolves, it has become clear that while some areas of the T cell response have been investigated in some detail, others, such as the T cell response in children remain largely unexplored. Therefore, this review will also highlight areas where T cell phenotypes require urgent characterisation

Characterization of clonal and regenerative perivascular stem cells in human endometrium

Decidualization denotes the transformation of endometrial stromal cells into specialised secretory decidual cells, a process indispensable for pregnancy. Decidualization of the human endometrium is not dependent on an implanting embryo but initiated during the mid-luteal phase of the cycle by elevated progesterone levels and local paracrine signals. Consequently, decidualization is a reiterative process directly linked to menstrual repair and rapid oestrogen-dependent growth. The extraordinary regenerative ability of the endometrium depends on endometrial mesenchymal stem cells (eMSCs) with inexhaustible self-renewing and differentiation capacity. Cyclic regeneration and rapid proliferation also render the stroma intrinsically heterogeneous, harbouring not only eMSCs but also endometrial transit amplifying (eTAs), mature, and senescent fibroblast subpopulations. Several lines of evidence presented in this thesis demonstrated that imbalance in these subpopulations is associated with reproductive failure. Quantification of clonal (eMSCs/eTAs) cells in mid-luteal biopsies obtained in consecutive cycles revealed increased levels in the 2nd biopsy obtained from miscarriage but not infertile patients, indicating that the tissue response to injury (i.e. the 1st biopsy) differs between patient groups. Further, in-depth characterization of primary stromal cell cultures prior to in vitro fertilisation (IVF) treatment showed that disordered temporal changes in the secretome of decidualizing cultures are associated with subsequent implantation failure. Additional characterization of perivascular eMSCs, which drive endometrial regeneration, highlighted the unique properties of these cells in terms of gene expression, metabolism, clonogenic and angiogenic potential. Importantly, eMSCs also formed 3D structures that resemble the uterine mucosa when cultured in Matrigel. These novel organoids termed endometrial regenerative bodies (ERBs), epithelialize when co-cultured and decidualize in response to differentiation cues. In sum, I provided evidence that dyshomeostasis between stromal subpopulations, which may be caused by eMSCs deficiency or dysfunction, precedes reproductive failure. Further, the ability of eMSCs to form ERBs provides a powerful new tool to study physiological and pathological implantation events in vitro

Decidualization induces a secretome switch in perivascular niche cells of the human endometrium

The endometrial perivascular microenvironment is rich in mesenchymal stem-like cells that express type 1 integral membrane protein Sushi domain containing 2 (SUSD2) but the role of these cells in the decidual transformation of this tissue in pregnancy is unknown. We used an antibody directed against SUSD2 (W5C5) to isolate perivascular (W5C5+) and nonperivascular (W5C5−) fibroblasts from mid-luteal biopsies. We show that SUSD2 expression, and hence the ratio of W5C5+:W5C5− cells, changes in culture depending on cell-cell contact and activation of the Notch signaling pathway. RNA sequencing revealed that cultures derived from W5C5+ progenitor cells remain phenotypically distinct by the enrichment of novel and established endometrial perivascular signature genes. In an undifferentiated state, W5C5+-derived cells produced lower levels of various chemokines and inflammatory modulators when compared with their W5C5− counterparts. This divergence in secretomes was switched and became more pronounced upon decidualization, which transformed perivascular W5C5+ cells into the dominant source of a range of chemokines and cytokines, including leukemia inhibitory factor and chemokine (C-C motif) ligand 7. Our findings suggest that the decidual response is spatially organized at the embryo-maternal interface with differentiating perivascular cells establishing distinct cytokine and chemokine profiles that could potentially direct trophoblast toward maternal vessels and govern local immune responses in pregnancy