<i>E</i>. <i>histolytica</i> activates the NLRP3 inflammasome upon contact.

<p>PMA-differentiated THP-1 macrophages (<b>a-c, e-h</b>) and BMDM (<b>d</b>) treated for 30 min or the indicated time with live <i>Eh</i> at a 1:30 ratio, without inhibitors (<b>a, c, d</b>), or with the addition of 100 μM zVAD-fmk (<b>b</b>), 100 μM YVAD-fmk (<b>b</b>), bafiolmycin A (<b>g</b>) or cytochalasin D (<b>g</b>) to the cultures before stimulation. Secretion and processing of IL-1β was determined by immunoblot and enzyme-linked immunosorbent assay (<b>a, b, d, g</b>). Secretion of active caspase-1 cleavage products (p20 and CARD, human; p10, mouse) was determined by immunoblot (<b>a, b, d, g</b>). (<b>c</b>) Caspase-1 activation after 30 min with LPS Nigericin or upon contact with <i>Eh</i> in which active caspase-1 was stained with YVAD-FLICA, red; mammalian nuclei, blue (<i>Eh</i> nuclei are not stained). (<b>e, h</b>) Localization of endogenous NLRP3 after stimulation with <i>Eh</i> or LPS Nigericin. (<b>f, h</b>) Localization of F-actin after <i>Eh</i> stimulation; CFSE-labeled <i>Eh</i>, purple. <i>Eh</i>, <i>E</i>. <i>histolytica</i>; Mϕ, macrophages; Baf, bafiolmycin A; CytoD, cytochalasin D; MSU, monosodium urate; SN, supernatants; LYS, cell lysates. Scale bars, 10 μM. Data are representative of three separate experiments (error bars SEM). ***P < 0.005.