Cridanimod (10-carboxymethyl-9-acridanone, CMA) is a potent STING agonist that directly binds to STING and triggers a strong antiviral response through the TBK1/IRF3 route.

STING (mouse):3.5 μM (Kd)

CMA induced robust IRF3 phosphorylation that was followed by strong Ifnb mRNA induction and translation. CMA-mediated IFNβ production reached peak levels already 4?h after stimulation, even exceeding LPS in its readiness to trigger IFNβ synthesis [1]. rSTING and hSTING do not respond or only respond weakly to CMA, whereas it strongly activated mSTING. Endogenous mRNA level of Ifnb, Cxcl10, and Il6 were robustly increased when treated with CMA in murine macrophages, but not in rat macrophages and human THP-1 cells [2].

For transfection experiments, primary macrophages were seeded with a density of 1 × 10^5?per?ml. Cells were transfected with poly(I:C) (2?μg/ml), pppRNA (1.33?μg/ml), ISD (2?μg/ml) and c-diGMP (8.66?μg/ml) using Lipofectamine 2000, according to the manufacturer's instructions. LPS (200?ng/ml) and CMA were directly added to the medium. Human PBMCs were transfected as described above, at a density of 4 × 10^6?per?ml, human fibroblasts at a density of 1.5 × 105?per?ml. For western blot experiments, cells were lysed after 2?h, if not indicated otherwise. For cytokine assays, supernatants were collected after 18–20?h. For RNA isolation, cells were lysed after 4?h [1].