Fig. 6: Ablation in MCOLN1 weakens mice resistance to DSS administration.

a C57BL/6 mice were injected with human recombinant IL-1β by intravenous injection (i.v) through tail veins three times during DSS administration as illustrated and administrated with ML-SA5 by intraperitoneal (i.p) injection nine times before and during DSS administration as described in the methods. b–e Serum IL-1β levels (b), percentage of weight changes (c), colon length (d), and DAI index (e) of mice treated with 3% DSS administration (n = 5), 3% DSS + ML-SA5 administration (n = 5), or 3% DSS + ML-SA5 (0.1 mg/kg) + IL-1β (0.01 mg/kg) administration (n = 5) for 6 days (measured at day 7). Initial weight of each mouse was defined as 100%. f Comparison of survival rate for WT and MCOLN1^−/− mice treated with 3% DSS for 6 days. The mice were then followed until day 13. n = 6. g Percentage of weight changes in WT, MCOLN1^−/−, or MCOLN1^−/− mice treated with vehicle or 3% DSS for 6 days. h Colon length of WT, MCOLN1^−/−, or MCOLN1^−/− mice treated with vehicle or 3% DSS for 6 days. n = 6. i IL-1β levels in serum collected from WT, MCOLN1^−/−, or MCOLN1^−/− mice treated with vehicle or 3% DSS for 6 days (measured at day 7), as assessed by ELISA assay. The line inside the box denotes the median value, while the top and bottom of the box contain the 25th to 75th percentiles of the dataset. The whiskers indicate the minimum and maximum values. n = 6. j A working model illustrates that TRPML1 channel is activated secondarily to the accumulated ROS at the late stage of the inflammation process in macrophages, which in turn triggers the release of lysosomal Fe²⁺ to the cytosol, resulting in activation of PHDs. Activated PHDs subsequently restrain NF-κB in the cytosol, leading to suppression of macrophage IL1B transcription and resultant production and secretion of IL-1β from macrophages. As a result, the property of controlling production and subsequent release of IL-1β from macrophages allows the lysosome to finely limit excessive inflammatory responses after an initial insult has been dealt with. Means ± SEMs were shown in a–h. Significant differences were evaluated using one-way ANOVA followed by Tukey’s test.