Characterization of a Novel Compound that Stimulates STING-Mediated Innate Immune Activity in an Allele-Specific Manner

A small molecule termed M04 behaves as a novel agonist of human STING. Importantly, we find that the molecule exhibits a differential ability to activate STING based on the allelic variant examined. Furthermore, while M04 is inactive in mice, expression of human STING in mouse cells rescues reactivity to the compound. Using primary human cells in ex vivo assays we were also able to show that M04 is capable of simulating innate responses important for adaptive immune activation such as cytokine secretion, dendritic cell maturation, and T cell cross-priming. Collectively, this work demonstrates the conceivable utility of a novel agonist of human STING both as a research tool for exploring STING biology and as an immune potentiating molecule. PBMCs from two healthy human donors were obtained and treated with DMSO vehicle, M04, cGAMP, or the TLR4/TRIF agonist LPS. RNA sequencing was then used to measure individual transcript levels in each sample and comparisons to vehicle-treated cells were made. Reads were aligned to the Homo_sapiens.GRCh38 genome in Ensembl along with its corresponding annotation, release 84. The program STAR (v020201) was used to align the reads to the genome. Two-pass mode was used with default parameters. Since STAR utilizes the gene annotation file, it calculated the number of reads aligned to each gene.