217-LB: Heterogeneity of Single Cells Obtained from Peripheral Blood Mononuclear Cells Collected from Youth with Recent-Onset Type 1 Diabetes

Abstract

Whole blood bulk RNA sequencing has been used to guide T1D clinical trial design and assess response to disease modifying interventions, whereas it is with limited information about cell specific gene expression changes. Here, we aimed to apply computational strategies to deconvolute cell type composition using cell specific gene expression references. Single-cell RNA sequencing (scRNA-seq) was conducted to profile 108,795 peripheral blood mononuclear cells obtained from 5 youth within 48 hrs of Stage 3 T1D onset (avg age 11.4; 3M;2F) and 5 age- and sex-matched controls and identified 31 distinct cell clusters. In T1D, the proportion of CD4+ T central memory (TCM) cells was increased (P = 0.018), while plasmacytoid dendritic cells (pDC), platelets, and hematopoietic stem and progenitor cells (HSPC) proportions were reduced (P = 0.021, 0.012 and 0.017 respectively) compared to controls. The most robust transcriptomic changes were observed in CD14+ and CD16+ monocyte populations and CD1C+ conventional type-2 dendritic (cDC2) cells. Using this scRNA-seq reference dataset, we ran computational algorithms CIBERSORTx and our in-house reference-free method ICTD to deconvolute cell proportions using public clinical trial data testing the anti-CD20 monoclonal antibody rituximab (n=37) vs. placebo (n=17). Strong correlation was observed between the methods for cell proportion estimates (P < 2.2*10-16). It showed that B cell subsets were reduced by rituximab. At baseline, non-responders had a higher proportion of CD8+ T cells (P = 0.04), and responders had higher proportions of neutrophils (P =0.04). These data suggest that deconvolution approaches can be utilized for secondary analysis of existing clinical trial bulk RNA-seq data, to link cell specific immune signatures associated with drug responder status. Disclosure W. Wu: None. C. Parks-schenck: None. T. Guo: None. C. Zhang: None. R. G. Mirmira: None. C. Evans-molina: Advisory Panel; Provention Bio, Inc., DiogenX, Avotres Inc., Neurodon, MaiCell Therapeutics, Other Relationship; Isla Technology, Bristol-Myers Squibb Company, Nimbus Therapeutics, Research Support; Lilly, Astellas Pharma Inc. Funding dkNET; Indiana University Center for Diabetes and Metabolic Diseases; National Institutes of Health (U01DK127786)