AB230 Abstracts
795
MONDAY
G Protein-Coupled Receptor Kinase-3 (GRK-3) In Bone Marrow Niche Interactions and Transplantation Jaime M. Brozowski1,2, Roman Timoshchenko2, Jessica Koontz3, Janet Rubin3,4, Matthew Billard2, Teresa K. Tarrant2,3; 1Department of Microbiology and Immunology, University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA, 2Thurston Arthritis Research Center and Department of Medicine, Division of Rheumatology, Allergy, and Immunology, University of North Carolina, Chapel Hill, NC 27599, USA, 3 School of Medicine, University of North Carolina, Chapel Hill, NC 27599, USA, 4Pediatrics and Pharmacology and Department of Medicine, Division of Endocrinology and Metabolism, University of North Carolina, Chapel Hill, NC 27599, USA. RATIONALE: Hematopoietic stem cell transplantation (HCT) is performed as an approach to address multiple forms of cancer and hereditary diseases including immune deficiency, though patient outcome of immune reconstitution is variable. Our study explores the effect of G proteincoupled receptor kinase-3 (GRK-3) on hematopoietic (HSCs) and mesenchymal stem cells (MSCs) in the bone marrow (BM) niche. We hypothesize when GRK-3 regulation is absent it may enhance leukocyte engraftment in HCT through functional effects on proliferation, differentiation, and homing that are in part mediated through the CXCL12/CXCR4 signaling axis. METHODS: MSCs were isolated from C57BL/6 and GRK-3 deficient (-/-) mice and supplemented with adipogenic or osteogenic media for differentiation analysis. MSC proliferation was determined by absorbance after addition of CCK-8, and HSC proliferation was determined by colony forming unit (CFU-GM) assay in the absence and presence of CXCL12. In vivo CFU-spleen (CFU-S) assay quantitatively assessed primitive BM cells by colony formation counts on day 8. RESULTS: Our studies show GRK-3(-/-) mice have increased HSCs and total leukocytes in the BM and blood. GRK-3(-/-) HSCs have increased proliferation, which is enhanced in the presence of CXCL12. GRK-3(-/-) MSCs have an increased proliferation and differentiate into osteogenic progenitor cells more readily. In vivo CFU-S data revealed enhanced colony formations on the explanted spleen with utilization of either GRK-3(-/-) donor marrow or GRK-3(-/-) recipients, with an additive effect of GRK-3(-/-) donor marrow into GRK-3(-/-) recipients. CONCLUSIONS: These data indicate a positive effect of GRK-3 deficiency on HCT and hematopoiesis with regards to both MSC and HSC function.
796
Allogeneic Hematopoietic Stem Cell Transplantation For Immune Dysregulation, Polyendocrinopathy, X-Linked (IPEX) Syndrome Resolves Enteropathy and Autoimmunity: A Single Institution Experience Dr. Zeynep Yesim Yesim Kucuk, MD, Dr. Jack J. H. Bleesing, MD, PhD, Dr. Rebecca A. Marsh, MD, Dr. Kejian Zhang, MD, Dr. Stella Davies, MBBS, PhD, Dr. Alexandra H. Filipovich, MD; Cincinnati Children’s Hospital Medical Center, Cincinnati, OH. BACKGROUND: Immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX) syndrome is a rare, life-threatening systemic autoimmune disease caused by mutations in the FOXP3 gene resulting in failure to develop functional T regulatory (Tregs) lymphocytes. Patients usually present in infancy with a clinical triad of intractable diarrhea, diabetes, eczema and require lifelong immunosuppression. However, immunosuppression does not adequately control all symptoms nor prevent premature mortality. Hematopoietic stem cell transplantation offers a viable option leading to prolonged survival and improved quality of life. RATIONALE: To report long term outcomes of 7 patients with IPEX syndrome following hematopoietic stem cell transplantation (HSCT). METHODS: Retrospective analysis of 7 patients with IPEX who underwent HSCT between 2000-2012 at a single institution.
J ALLERGY CLIN IMMUNOL FEBRUARY 2014
RESULTS: Seven patients with IPEX underwent allogeneic HSCT. Myeloablative conditioning was used in three patients and reduced intensity conditioning in four patients. Four patients are currently alive without immunosuppressive drugs, surviving 4 to 7 years post transplant. The overall survival was 80% in last decade. The earlier age at transplantation resulted in long-term survival. All survivors experienced reconstitution of Tregs with resolution of enteropathy and autoimmunity. CONCLUSIONS: HSCT results in development of functional Tregs with reversal of autoimmune enteropathy.
797
Natural Killer Cell Immunoglobulin Like Receptor (KIR) Genetic Profile Is a Strong Predictor Of Allogeneic Hematopoietic Cell Transplant Outcomes Dr. Rehan M. Faridi, PhD1, Taylor Kemp1, Dr. Poonam Dharmani, PhD1, Dr. Victor Lewis, MD2, Dr. Noureddine Berka, PhD3, Dr. Jan Storek, MD, PhD1, Dr. Faisal Khan, PhD1; 1University of Calgary, Calgary, AB, Canada, 2Alberta Children’s Hospital, Calgary, AB, Canada, 3 Calgary Laboratory Services, Calgary, AB, Canada. RATIONALE: In spite of high resolution HLA matching and optimal care, complications of allogeneic hematopoietic cell transplantation (alloHCT), including graft versus host disease (GVHD), relapse of the underlying disease and reactivation of otherwise latent viral infections are substantial. Recently, natural killer (NK) cell genetic system, regulated by activating and inhibitory Killer Immunoglobulin-like Receptors (KIR) has garnered substantial research interest as a modifier of HCT outcomes. Here we set out to determine the influence of KIR gene repertoires of HCT pairs on allo-HCT complications including GVHD, relapse, posttransplant lymphoproliferative disorder (PTLD) and cytomegalovirus (CMV) reactivation. METHODS: KIR typing was obtained for 92 and 111 (discover and validation cohorts) HLA- matched antithymocyte globulin (ATG) conditioned allo-HCT pairs and 50 healthy individuals by Luminex-based rSSO method. Effect of KIR genotypes on HCT outcomes was analyzed using binomial regression and Kaplan-Meier tests. PBMNCs from healthy volunteers were stimulated against different targets to enumerate KIRdependent target-specific NK cell response. RESULTS: Significant protection against GVHD was observed in donorrecipient pairs matched for the KIR-AA and B/x genotypes (HR52.224; p50.01) without any effect on disease relapse (HR51.098; p50.934). Donor KIR-centromeric linkage group was strongly associated with the incidence of PTLD (p50.01). Higher activating donor-KIR conferred protection against CMV reactivation (p50.02). A unique target-induced functional response with higher number of herpes-virus induced functional NK cells in individuals lacking KIR-centromeric linkage group was observed. CONCLUSIONS: NK cell responsiveness, a function of KIR gene repertoire modified the risk of GVHD, PTLD and CMV reactivation indicating relevance of KIR gene profiling for predicting HCT outcomes.