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Browsing by Author "Ramadan, Abdulraouf M."
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Item From proteomics to discovery of first-in-class ST2 inhibitors active in vivo(American Society for Clinical Investigation, 2018-07-26) Ramadan, Abdulraouf M.; Daguindau, Etienne; Rech, Jason C.; Chinnaswamy, Krishnapriya; Zhang, Jilu; Hura, Greg L.; Griesenauer, Brad; Bolten, Zachary; Robida, Aaron; Larsen, Martha; Stuckey, Jeanne A.; Yang, Chao-Yie; Paczesny, Sophie; Pediatrics, School of MedicineSoluble cytokine receptors function as decoy receptors to attenuate cytokine-mediated signaling and modulate downstream cellular responses. Dysregulated overproduction of soluble receptors can be pathological, such as soluble ST2 (sST2), a prognostic biomarker in cardiovascular diseases, ulcerative colitis, and graft-versus-host disease (GVHD). Although intervention using an ST2 antibody improves survival in murine GVHD models, sST2 is a challenging target for drug development because it binds to IL-33 via an extensive interaction interface. Here, we report the discovery of small-molecule ST2 inhibitors through a combination of high-throughput screening and computational analysis. After in vitro and in vivo toxicity assessment, 3 compounds were selected for evaluation in 2 experimental GVHD models. We show that the most effective compound, iST2-1, reduces plasma sST2 levels, alleviates disease symptoms, improves survival, and maintains graft-versus-leukemia activity. Our data suggest that iST2-1 warrants further optimization to develop treatment for inflammatory diseases mediated by sST2.Item ST2/MyD88 deficiency protects mice against aGVHD and spares T-regulatory cells(American Association of Immunologists, 2020-04-12) Griesenauer, Brad; Jiang, Hua; Yang, Jinfeng; Zhang, Jilu; Ramadan, Abdulraouf M.; Egbosiuba, Jane; Campa, Khaled; Paczesny, Sophie; Medicine, School of MedicineAcute graft-versus-host disease (aGVHD) hinders the efficacy of allogeneic hematopoietic cell transplantation (HCT). Plasma levels of soluble membrane-bound ST2 (ST2) are elevated in human and murine aGVHD and correlated to type 1 T cells response. ST2 signals through the adapter protein MyD88. The role of MyD88 in T cells during aGVHD has yet to be elucidated. We found that knocking out MyD88 in the donor T cells protected against aGVHD independent of IL-1R and TLR4 signaling in two murine HCT models. This protection was entirely driven by MyD88-/- CD4 T cells. Transplanting donor MyD88-/- conventional T cells (Tcons) with wild-type (WT) or MyD88-/- regulatory T cells (Tregs) lowered aGVHD severity and mortality. Transcriptome analysis of sorted MyD88-/- CD4 T cells from the intestine 10 d post-HCT showed lower levels of Il1rl1 (gene of ST2), Ifng, Csf2, Stat5, Batf, and Jak2 Transplanting donor ST2-/- Tcons with WT or ST2-/- Tregs showed a similar phenotype with what we observed when using donor MyD88-/- Tcons. Decreased ST2 was confirmed at the protein level with less secretion of soluble ST2 and more expression of ST2 compared with WT T cells. Our data suggest that Treg suppression from lack of MyD88 signaling in donor Tcons during alloreactivity uses the ST2 but not the IL-1R or TLR4 pathways, and ST2 represents a potential aGVHD therapeutic target sparing Tregs.