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Vulcanodinium rugosum-produced Portimine A triggers human skin epithelial cell necrosis and IL-1 cytokine release. (A) Map of the Senegalese coast showing the location of the outbreak and the sampling sites i.e., red star (a) (14.33 N; −17.15 W), (b) (14.32 N; −17.10 W) and (c) (14.29 N; −17.05 W). Samples from different environmental compartments: (I) biomass from fishing canoe, (II) biomass from fishing drift-net, (III) GF/F filtered seawater, (IV) marine sediment, (V) mussel flesh. (B) Light microscopy images of Vulcanodinium rugosum (sample I, 2020): living cells and temporary cysts. (C) LC-MS/MS chromatogram of toxin profile (sample I, 2020) and chemical structures of Portimine A and Pinnatoxin H and concentrations of V. rugosum toxins in the samples I–V, quantified by LC-MS/MS. N.B. All mussel (c) data are from 2021. PnTX: Pinnatoxin, Port: Portimine. (D) Cytokine analysis 24 h after exposure of primary human keratinocytes (pHEKs) to purified extracts derived from Sample II isolated in (C, red), diluted 1/20,000. Representative experiment of three independent replicates. (E) Quantification of cell lysis (LDH) and IL-1α, IL-1β, or IL-18 release in pHEKs treated with Sample II (1/20,000) for 24 h. When specified, the pan-caspase inhibitor (Z-VAD, 20 µM), Caspase-1 inhibitors (Z-YVAD, 20 µM or VX-765, 10 µM) were used. ***P ≤ 0.0001, two-way ANOVA with multiple comparisons. Values are expressed as mean ± SEM. Graphs show one experiment performed in triplicates at least three times. (F) Cell lysis (LDH) and IL-1β or IL-18 release evaluation in pHEKs upon pure Portimine A (4 ng/mL) or Pinnatoxins-H/G (40 ng/mL) exposure for 24 h. When specified, the -caspase inhibitor (Z-VAD, 20 µM), Caspase-1 inhibitors (Z-YVAD, 20 µM or VX-765, 10 µM) were used. ***P ≤ 0.0001, two-way ANOVA with multiple comparisons. Values are expressed as mean ± SEM. Graphs show one experiment performed in triplicates at least three times. Source data are available online for this figure.
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