OLT1177, a beta-sulfonyl nitrile compound, safe in humans, inhibits the NLRP3 inflammasome and reverses the metabolic cost of inflammation

Activation of the NLRP3 inflammasome induces maturation of IL-1beta and IL-18, both validated targets for treating acute and chronic inflammatory diseases. Here, we demonstrate that OLT1177, an orally active beta-sulfonyl nitrile molecule, inhibits activation of the NLRP3 inflammasome. In vitro, nanomolar concentrations of OLT1177 reduced IL-1beta and IL-18 release following canonical and noncanonical NLRP3 inflammasome activation. The molecule showed no effect on the NLRC4 and AIM2 inflammasomes, suggesting specificity for NLRP3. In LPS-stimulated human blood-derived macrophages, OLT1177 decreased IL-1beta levels by 60% and IL-18 by 70% at concentrations 100-fold lower in vitro than plasma concentrations safely reached in humans. OLT1177 also reduced IL-1beta release and caspase-1 activity in freshly obtained human blood neutrophils. In monocytes isolated from patients with cryopyrin-associated periodic syndrome (CAPS), OLT1177 inhibited LPS-induced IL-1beta release by 84% and 36%. Immunoprecipitation and FRET analysis demonstrated that OLT1177 prevented NLRP3-ASC, as well as NLRP3-caspase-1 interaction, thus inhibiting NLRP3 inflammasome oligomerization. In a cell-free assay, OLT1177 reduced ATPase activity of recombinant NLRP3, suggesting direct targeting of NLRP3. Mechanistically, OLT1177 did not affect potassium efflux, gene expression, or synthesis of the IL-1beta precursor. Steady-state levels of phosphorylated NF-kappaB and IkB kinase were significantly lowered in spleen cells from OLT1177-treated mice. We observed reduced IL-1beta content in tissue homogenates, limited oxidative stress, and increased muscle oxidative metabolism in OLT1177-treated mice challenged with LPS. Healthy humans receiving 1,000 mg of OLT1177 daily for 8 d exhibited neither adverse effects nor biochemical or hematological changes.

• Marchetti, C.
• Swartzwelter, B.
• Gamboni, F.
• Neff, C. P.
• Richter, K.
• Azam, T.
• Carta, S.
• Tengesdal, I.
• Nemkov, T.
• D'Alessandro, A.
• Henry, C.
• Jones, G. S.
• Goodrich, S. A.
• St Laurent, J. P.
• Jones, T. M.
• Scribner, C. L.
• Barrow, R. B.
• Altman, R. D.
• Skouras, D. B.
• Gattorno, M.
• Grau, V.
• Janciauskiene, S.
• Rubartelli, A.
• Joosten, L. A. B.
• Dinarello, C. A.