Abstract

Dendritic cells (DCs) are a heterogeneous cell population that are key regulators of protective immune responses and tolerance to self-antigens. There is a strong scientific rational for using tolerogenic DCs (Tol-DCs) therapeutically for autoimmune diseases. DCs have been used successfully in clinical studies, many of which were carried out with ex-vivo generated monocyte-derived DCs using immunomodulatory agents such as dexamethasome and vitamin D3. Several studies also show that IL10-modulated DCs are potent inducers of regulatory T cells.
The goal of our work was to find novel drugs that induce a stable tolerance in autoimmune disease patients by inducing Tol-DCs. A phenotypic approach was used to identify small molecule inducers of Tol-DCs using high throughput flow cytometry. Two 384 well screens were conducted: One to screen for Tol-DC inducers in differentiated DCs (phenotype change); and one to screen for Tol-DC inducers in monocyte progenitor cells (cell fate change).
Initially a 20,000 diverse compound training set was screened in each assay. Data from each screen was input into an AI-driven, iterative, active learning strategy for hit identification with the goals of reducing the total number of molecules to screen and guiding the exploration of our HTS collection to maximise diversity. Up to 10 iterations in each screen were performed. Identified hits were subjected to further confirmatory assays before target identification studies using chemoproteomics and thermoproteomics.
Several unique chemical series have been identified that modulate DC tolerance. Efforts are ongoing to identify the molecular targets and pathways involved.


“The human biological samples were sourced ethically, and their research use was in accord with the terms of the informed consents under an IRB/EC approved protocol.”

Contributors:
Jonathan Lea, Rob Jepras, Abdul Mannan Baru, James Rowedder, Bhumika Karamshi, David Marcus, Semra Kitchen and Melanie Leveridge
(All affiliated to GSK, Stevenage)