REPOGRAMING OF THE INTESTINAL IMMUNE CELL COMPARTMENT DEFINES THE RESPONSE TO AUTOLOGOUS STEM CELL TRANSPLANTATION IN CROHNS DISEASE

Abstract

Abstract INTRODUCTION For the treatment of refractory Crohn’s disease (CD) autologous stem cell transplant (auto-SCT) is unparalleled in its ability to induce clinical and endoscopic remission.(1, 2) Auto-SCT is unique as a cellular therapy aimed to reset immune pathophysiology to a pre-disease state using hematopoietic stem cells. As such, the study of how the immune system responds to auto-SCT will provide unique insight into CD pathogenesis and treatment. To date, no studies in any cohort have defined the mucosal and peripheral immune response to auto-SCT. Here we report initial studies of high dimensional immune phenotyping of patients with CD during auto-SCT. METHODS Patients with CD were enrolled in a Phase IIa study of auto-SCT (NCT03219359). 14 patients were transplanted (2018-2022). Paired blood and intestinal samples were taken prior to transplant and 6 months post-transplant. Fresh leukocytes were isolated and analyzed by mass cytometry (CyTOF). Supervised clustering of immune cell populations using canonical markers was performed in parallel with unsupervised clustering by FlowSOM.(3) RESULTS After 6 months post-transplant,12/13 patients had an endoscopic response (↓SES-CD by 50%) and 10/13 patients were in endoscopic remission (SES-CD<4). Supervised clustering of major immune cell subsets demonstrated distinct site-specific responses to transplant in myeloid and lymphoid cell populations (Fig 1). Naïve CD4+ and CD8+ T cells universally decrease in number at 6 months post-transplant whereas all other B and T cell populations have discordant changes in the blood and intestine, especially naïve and transitional CD27- B cell populations which significantly increase in blood and decrease in the intestine. CD14+ populations are universally increased in number post-transplant with a specific increase in CD14+ CD206+ macrophages in the intestine. Unsupervised clustering of blood and intestinal immune cells resolve 100 cell clusters that correlate with canonical immune cell markers (Fig 2). Unsupervised analysis further highlights a significant increase in multiple intestinal CD14+CD206+ immune cell populations reflecting newly arrived and/or differentiating and mature monocyte derived macrophages. Principal component and hierarchical clustering analyses of immune cell clusters suggest a reprograming of the intestinal immune compartment post-transplant whereas changes in circulating immune cells populations fail to separate the pre and post-transplant states. CONCLUSION We demonstrate for the first time differences in the intestinal and peripheral immune response to auto-SCT. These studies highlight the changes in intestinal immune cell networks that define the transplant response perhaps through CD14+ cells.