654 Analysis of IDO-1 expression on dendritic cells and factors influencing its up- and downregulation in pancreatic cancer

Background Pancreatic Ductal Adenocarcinoma (PDAC) is bad. An immunosuppressive tumor microenvironment (TME) with an excess of immune cells and cytokine/chemokine factors contribute to local systemic immunosuppression in PDAC. 1 Our laboratory has generated single-cell RNA-Sequencing (scRNA-Seq.) data from spleens derived PDAC patients healthy counterparts. This demonstrates the existence dendritic cell (DC) subsets a tolerogenic phenotype. These DCs display increased expression several markers, including Indoleamine 2,3-dioxygenases (IDO-1 IDO-2), widely accepted as markers for specific population DCs: DCs. evoke signal leading activation regulatory T MDSCs well apoptosis CD8+ CD4+ effector cells. 2 3 Methods To validate our scRNA-Seq. data, we performed pilot investigations harvesting spleen subjects. Besides examining human specimens, also investigated IDO-1 on splenic tumor-bearing mice, orthotopically implanted LSL-KrasG12D; LSL-Trp53R172H/+; Pdx1-Cre (KPC)-derived lines. It known that tumor-derived exosomes can impact DC-differentiation 4 Exosome purification using differential ultracentrifugation well-established method lab optimized autopsy samples. We analyzed their potential modulating vitro assays. Briefly, incubated different exosome concentrations harvested RNA-sequencing flow cytometry. Results Compared normal spleens, displayed higher (figure 1). Additionally, KPC-tumor-bearing mice showed blood compared wild-type mice. Further investigating influence PDAC-derived marker have shown apparent increase when culturing splenic-derived 2). Conclusions While are essential regulating homeostasis between response tolerance, 5 studies overexpression cancer. Investigating part lab's efforts understand nature Future directions this project include determining molecular pathways regulate IDO-1. will investigate downstream mechanisms through which modulate switch plan further characterize DC populations by evaluating interplay other context antigen-specificity influencing these cells' properties. References Mundry CS, Eberle KC, Singh PK, Hollingsworth MA, Mehla K. Local pancreatic cancer: targeting stalwarts tumor's arsenal. BBA - Reviews Cancer 2020; 1874 (1):188387. Liu M, Wang X, L, Ma Gong Z, Zhang S, Li Y. Targeting IDO1 pathway bench bedside. Journal Hematology & Oncology 2018; 11 (1):100. Hornyák Dobos N, Koncz G, Karányi Páll D, Szabó Halmos Székvölgyi L. The role Indoleamine-2,3-Dioxygenase cancer development, diagnostics, therapy. Frontiers immunology 9 :1. Bronte V, Pittet MJ. regulation immunity. Immunity 2013; 39 (5):806–818. Domogalla MP, Rostan PV, Raker VK, Steinbrink Tolerance education: how shape Immunology 2017; 8 :1764. Ethics Approval study was approved University Nebraska Medical Center Board; approval numbers IRB#: 440-16-EP 091-01. Abstract 654 Figure Expression IDO-2 (blue) .and (orange) Change treatment