Figure 4. Recruited inflammatory monocytes are the main source of IL-1β during DSS-induced colitis.

(A) Total LP cells isolated on day 0 (naive) and on day 7 (DSS) after DSS treatment were cultured for 3 hrs and left unstimulated or cultured in the presence of 5 mM ATP for the additional 30 min. IL-1β and IL-6 were measured from culture supernatant.

(B) and (C) Total LP cells were isolated at indicated times from WT mice given 2.5% DSS from day 0 to day 7. (B) IL-1β was measured from culture supernatant after 3 hrs of culture. (C) Percent of inflammatory monocytes (CD11b⁺Ly6C^high) in CD45⁺ LP cells was determined by flow cytometry. Open circles represents means of values from individual mice.

(D) Total LP cells were isolated from DSS-treated mice on day 7 after 2.5% DSS treatment and CD45⁺ cells were sorted according to CD11b and Ly6C expression. Sorted cells were cultured for 3 hrs and IL-1β in culture supernatant and Nlrp3 mRNA expression was analyzed by ELISA and qRT-PCR, respectively.

(E) WT, Aim2^−/−, Nlrc4^−/−, Nlrp3^−/−, and Pycard^−/− mice were treated with 2.5% DSS for 7 days. Sorted inflammatory monocytes were cultured for 3 hrs and IL-1β was measured in culture supernatant.

(F) GF and SPF mice were treated with 2% DSS for 6 days. Sorted inflammatory monocytes (IM) were cultured for 3 hrs and IL-1β was measured in culture supernatant.

(G) WT and Ccr2^−/− mice were treated with 2.5% DSS for 7 days. Total LP cells were cultured for 3 hrs and IL-1β was measured in culture supernatant.

(H) IL-1β release by total LP cells isolated from indicated chimera mice. Mice received PBS or diphtheria toxin (DT) on day 0, 3, and 6. LP cells were isolated on day 7 and cultured for 3 hrs to measure cytokine concentrations in culture supernatant.

Data are representative of at least two experiments. Values are means of triplicate samples ± SD. *p < 0.05, **p < 0.01, ***p < 0.001. See also Figure S1.