Fig. 1.
NLRP3 deficiency attenuates DSS-induced colitis and inflammasome activation in mice. Nlrp3−/− and Nlrp3+/+ littermates were treated with 3% DSS dissolved in drinking water for 5 days and DSS-free drinking water for another two days. A Wild-type and Nlrp3 knockout mice were identified by PCR with specific primers. Representative electrophoretic analysis of PCR products from Nlrp3+/+ (446 bp) and Nlrp3−/− (559 bp) mice is shown. B NLRP3 depletion protected mice from DSS-induced weight loss. Weight loss during DSS treatment is expressed as the percent change from Day 0. C NLRP3 depletion protected mice from DSS-induced increases in DAI scores. Weight loss, diarrhea and rectal bleeding were recorded and scored daily; the DAI score was the sum of these scores. D, E NLRP3 depletion protected the colon from DSS-induced shortening. Representative photographs of the colon in each group are shown (D), and the length of the colon was compared among groups (E). F, G NLRP3 depletion protected the colon against DSS-induced injuries and immune cell infiltration. Representative images of colonic sections (H&E. staining) are shown (F). Scale bars, 100 µm. The histology score of each colon section was quantified and compared among groups (G). H, I NLRP3 depletion inhibited ASC speck formation in the DSS-exposed colon. Frozen sections of the colon were obtained and incubated with antibodies against ASC, and nuclei were counterstained with Hoechst 33342. Representative immunofluorescence images of colonic ASC are shown, and white arrows indicate ASC specks (H). Scale bars, 20 µm. The number of ASC specks in each colonic section was quantified (I). J NLRP3 depletion decreased the release of IL-1β from the DSS-exposed colon. The proximal colon (1–2 cm) was opened longitudinally and incubated in serum-free RPMI-1640 medium at 37 °C (5% CO2) for 24 h. The concentration of IL-1β in the supernatants was measured by a cytometric bead array and normalized to the total protein concentration (pg/mg protein). The data are expressed as the mean ± SD, and statistical analyses were performed using Student’s t test. *p < 0.05, **p < 0.01, ***p < 0.001