Fig 6.

Lead ENPP1 inhibitor, compound E-3, elicits enhanced cGAS-STING-IRF3 pathway activation and type I interferon release in macrophages. (A) Compound E-3 (NCI 14465) elicits enhanced IRF3 activation in RAW-Blue IRF3-SEAP reporter mouse macrophages at 24 h following 2′,3′-cGAMP transfection. Briefly, reporter macrophages were pre-treated with compound E-3 at concentrations varying from 0 to 165 mM (165 mM is 6.2× the ENPP1 IC₅₀ and 20.5 mM is 0.75× the IC₅₀) and were subsequently transfected with 1 nM 2′,3′-cGAMP using the X-tremeGENE9 transfection reagent. Culture supernatants were collected 24 h after transfection, and SEAP activity was measured by colorimetry in the presence of the QUANTI-Blue detection reagent. (B) Compound E-3 elicits elevated interferon-β (IFN-β) responses in human monocyte-derived macrophages (hMDMs) stimulated with 2′,3′-cGAMP. hMDMs were pre-treated with compound E-3 at 165 µM and subsequently transfected with 2′,3′-cGAMP (1 nM) using the X-tremeGENE9 transfection reagent. At 24 h post-transfection, culture supernatants were evaluated for IFN- β levels via ELISA. All data are presented as mean values ± S.E.M. (n = 3 independent biological replicate experiments). Statistical analyses were done using a two-tailed Student’s t-test. P-values are shown for relevant comparisons.