Graft versus host disease (GVHD), mediated by donor T cells, is a significant source of morbidity and mortality following allogeneic stem cell transplantation. Mesenchymal stem cells (MSC) can successfully treat ongoing graft versus host disease, presumably due to their ability to suppress donor T cell proliferation. Little is known about the potential of MSC to prevent GVHD. Here we show that bone marrow-isolated MSC can suppress the development of GVHD if given after donor T cell recognition of antigen. IFN-c was required to initiate MSC efficacy. Recipients of IFN-c -/-T cells did not respond to MSC treatment and succumbed to GVHD. MSC, pre-treated with IFN-c, became immediately active and could suppress GVHD more efficiently than a fivefold-greater number of MSC that were not activated. When given at the time of bone marrow transplantation, activated MSC could prevent GVHD mortality (100% survival, p=0.006). MSC activation was dependent on the magnitude of IFN-c exposure, with increased IFN-c exposure leading to increased MSC suppression of GVHD. Activated MSC present a new strategy for preventing GVHD using fewer MSC. Key words: Mesenchymal stem cell Á GVH disease Á IFN-c See accompanying commentary by Dazzi and Marelli-Berg IntroductionAllogeneic hematopoietic stem cell transplants have the potential to play a significant curative role in the treatment of malignant and non-malignant hematopoietic disorders, autoimmune diseases, and immunological deficiencies, and in the induction of transplantation tolerance [1][2][3][4][5][6][7][8][9][10]. Widespread application of this therapeutic modality is limited due to the morbidity and mortality of graft versus host disease (GVHD), which affects 50% of stem cell transplant recipients [11][12][13][14][15][16]. While grafts highly matched to the recipient, young donors, donor/recipient sex match, and posttransplant immunosuppression are strategies used to reduce the risk of GVHD [17], thus far, the greatest preventative measure has been intentional underutilization of stem cell transplantation. Theoretically, strategies aimed at preventing GVHD would target early initiating factors either during the inflammatory milieu created in the wake of tissue damage from conditioning regimens [18,19] or during T cell antigen recognition and proliferation [20,21]. Once the efferent effector phase occurs, donor T cell-mediated destruction of host tissues occurs and preventive strategies are replaced with treatment regimens [19].Mesenchymal stem cells (MSC) have been used in the efferent phase of GVHD to successfully treat ongoing, acute, steroidresistant GVHD [22,23]. In contrast, when given at the time of BM transplant, for the prevention of GVHD, the incidence of grade III/ IV GVHD was not significantly improved [24], suggesting the [26,27,29,30]. In addition, MSC do not suppress the modest T cell proliferative response to recall antigens [31]. These findings suggest MSC may exert their optimal effects during the events surrounding larger scale T cell activation and proliferat...

The preferred source of carbon and energy for yeast cells is glucose. When yeast cells are grown in liquid cultures, they metabolize glucose predominantly by glycolysis, releasing ethanol in the medium. When glucose becomes limiting, the cells enter diauxic shift characterized by decreased growth rate and by switching metabolism from glycolysis to aerobic utilization of ethanol. When ethanol is depleted from the medium, cells enter quiescent or stationary phase G(0). Cells in diauxic shift and stationary phase are stressed by the lack of nutrients and by accumulation of toxic metabolites, primarily from the oxidative metabolism, and are differentiated in ways that allow them to maintain viability for extended periods of time. The transition of yeast cells from exponential phase to quiescence is regulated by protein kinase A, TOR, Snf1p, and Rim15p pathways that signal changes in availability of nutrients, converge on transcriptional factors Msn2p, Msn4p, and Gis1p, and elicit extensive reprogramming of the transcription machinery. However, the events in transcriptional regulation during diauxic shift and quiescence are incompletely understood. Because cells from multicellular eukaryotic organisms spend most of their life in G(0) phase, understanding transcriptional regulation in quiescence will inform other fields, such as cancer, development, and aging.

BackgroundOvarian cancer is the major cause of death among gynecologic cancers with 75% of patients diagnosed with advanced disease, and only 20% of these patients having a survival duration of five years. Treatments blocking immune checkpoint molecules, programmed cell death (PD-1) or its ligand PD-ligand- I (PD-L1) have produced a beneficial and prolonged effect in a subgroup of these patients. However, there is debate in the literature concerning the prognostic value of the expression of these molecules in tumors, with immunotherapy responsiveness, and survival.We evaluated the immune landscape of the ovarian tumor microenvironment of patients, by measuring the impact of the expression of tumor PD-1, PD-L1 and infiltrating lymphocytes on stage and grade of tumors and survival, in a cohort of 55 patients with gynecologic malignancies. Most patients under study were diagnosed with advanced disease ovarian cancer.ResultsOur studies revealed that a low density of PD-1 and of PD-L1 expressing cells in tumor tissue were significantly associated with advanced disease (P = 0.028 and P = 0.033, respectively). Moreover, PD-L1 was expressed significantly more often in high grade tumors (41.5%) than in low grade tumors of patients (7.7%) (P = 0.040). The presence of CD3 or of FoxP3 infiltrating cells with PD-L1 in patient tumors did not impact the significance of the association of PD-L1 with high grade tumors (P = 0.040), and our analyses did not show an association between the presence of PD-1 or PD-L1 and survival.ConclusionsWe conclude that a subgroup of advanced disease ovarian cancer patients with high grade tumors, expressing PD-L1, may be prime candidates for immunotherapy targeting PD-1 signaling.Electronic supplementary materialThe online version of this article (10.1186/s13048-018-0414-z) contains supplementary material, which is available to authorized users.

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