Presenting Author: Ariane Walsh
, Principal Scientist at Evotec
Abstract:
Tregs possess immunosuppressive properties that can restore and maintain immune homeostasis via various suppressive mechanisms. A marker of Tregs is the transcription factor Forkhead box P3 (FoxP3), which regulates Treg development and function. Autoimmune patients have shown dysfunction or reduction in FoxP3+ Tregs, highlighting the critical role of these cells in preventing pathogenic immune responses. There is great interest in developing medical interventions against autoimmune diseases by enhancing Treg function and/or numbers. Currently, a major limitation to generate efficient Treg therapies is the lack of selective targets as starting points for drug discovery.
To identify novel Treg targets, Evotec developed a CRISPR/Cas9-based arrayed screening platform using human CD4+ T-cells. About 8,000 genes were screened with a FACS read-out and the effect of gene knockout (KO) on the frequency of FoxP3+ Tregs was assessed. We identified ~450 targets where the KO led to an increase of FoxP3+ cells within the CD4+ T-cell compartment, indicating their potential for drug development starting points. In addition to FoxP3, the effect of KO on CD4+ conventional as well as Treg viability, proliferation and markers such as, CTLA-4, PD-1 or CD25 was monitored. The hits are being confirmed and the impact of the target KO on Treg function and phenotype assessed in a panel of in vitro assays. The goal is to identify novel Treg targeting product candidates to treat autoimmune diseases.