BACKGROUND AND STUDY OBJECTIVES

IL-23 is a cytokine that plays crucial role in the development of autoimmune inflammatory disorders such as psoriasis and inflammatory bowel disease (IBD). It is composed of two subunits, p40 and p19. Selective antibodies have been developed to target the p19 subunit to mitigate the effects of IL-23 overproduction. 

An orally administered small-molecule inhibitor of the IL-23 pathway has the potential to provide significant benefits for patients suffering from autoimmune inflammatory disorders. However, identifying small molecule inhibitors of the IL-23 pathway has proven to be a challenging process. 

A recent study used an extensive screening compound library and the iLite reporter gene cell system to identify potential inhibitors. This system allows for the identification of small molecules that target physiologically relevant target proteins, as well as the signaling pathway components and accessory proteins. 

The researchers screened around 24,000 compounds for selective IL-23 inhibition and further evaluated two potential sources of off-target inhibition:  cytotoxicity and specificity, using the iLite IFN-ɣ cells to determine non-specific inhibition.

STUDY OUTCOMES

During validation and optimization of the cell-based assay, it was shown that iLite IL-23 cells allow for a robust, sensitive, and specific assessment of IL-23 inhibition. In combination with iLite IFN-ɣ cells and a cytotoxic assay to determine their off-target impact, researchers were able to discard compounds that were unspecific or had cytotoxic effects. 

This resulted in 24 compounds that exhibited ≥80% maximum inhibition and <7 µM IC₅₀ on IL-23 signaling with >3-fold higher IC₅₀ for IFN-ɣ. The selective IL-23 inhibitors were identified and will be continued further testing, according to the authors. 

The study highlights the robustness of iLite cells’ performance and the capabilities of iLite cell customization, making them an excellent tool for small molecule screening.

CITATION

Varghese MT, Dudas LP, Allen EJ, et al. Optimization of a High-Throughput Cell-Based Screening Strategy to Identify Small-Molecule Inhibitors of IL-23 Signaling. SLAS Discov. 2021 Jan;26(1):122-129. doi: 10.1177/2472555220923362.