Figure 3 : Fenamates inhibit NLRP3 via reversible blockade of the Cl channel VRAC.

From: Fenamate NSAIDs inhibit the NLRP3 inflammasome and protect against Alzheimer’s disease in rodent models

Figure 3

(a) iBMDMs were primed with LPS (1 μg ml−1, 4 h) and pre-treated with NSAID, reversible caspase-1 inhibitor YVAD-CHO or irreversible NLRP3 inhibitor 3,4-methylenedioxy-β-nitrostyrene (MNS) (100 μM, 15 min) before washing 3 × 5 min (or no wash) and stimulation with ATP (5 mM, 1 h). (b) Cells were pre-treated with drug as above before either media replacement without drug, media replacement with drug or no media replacement followed by ATP stimulation. (ce) iBMDMs were primed as above. Currents were measured in the whole-cell configuration of the patch clamp technique. Voltage ramps were applied from −90 mV to +90 mV for a duration of 360 ms every 20 s. Non selective cation currents were evoked by 5 mM ATP and were measured in the absence (ATP) or presence of 100 μM flufenamic acid (c, n=8) or mefenamic acid (d, n=10). (fj) iBMDMs were primed as above before whole-cell volume-regulated chloride currents (VRAC) were induced by hypotonic extracellular medium. Currents were induced by 360 ms-lasting voltage ramps from −90 mV to +90 mV every 20 s. Examples of current recordings measured in the absence or presence of 100 μM ibuprofen (f, n=6), diclofenac (g, n=5), flufenamic acid (h, n=6), or mefenamic acid (i, n=6). ***P<0.001, NS, not significantly different, determined by one-sample t-test versus hypothetical value of 100%. (K) iBMDMs were primed as above and pre-treated with flufenamic acid, mefenamic acid, Cl channel blockers NPPB or DIDS (100 μM, 15 min) before stimulation with ATP (5 mM, 1 h). (l) iBMDMs were primed as above and pre-treated with DCPIB (10 μM, 15 min) before stimulation with ATP (5 mM, 1 h). IL-1β in the supernatants (a,b,k,l) was quantified by ELISA and data are presented as mean % IL-1β release versus vehicle (DMSO) control+s.e.m or mean IL-1β release (n=4). *P<0.05, **P<0.01, ***P<0.001, NS, not significantly different determined by one-way ANOVA with Tukey’s post hoc analysis (a) or one-sample t-test versus hypothetical value of 100% (bk). ###P<0.001 versus ATP (l).