Leptin: A pivotal mediator of intestinal inflammation in mice Britta Siegmund, Hans Anton Lehr, Giamila Fantuzzi  Gastroenterology  Volume 122, Issue 7, Pages 2011-2025 (June 2002) DOI: 10.1053/gast.2002.33631 Copyright © 2002 American Gastroenterological Association Terms and Conditions

Fig. 1 Direct stimulatory effect of leptin on LPMCs and IELs in vitro. LPMCs and IELs were isolated from the colons of healthy C57BL/6 mice. (A) LPMCs were stimulated for 24 hours in the presence or absence of leptin (100 ng/mL) or con A (0.5 μg/mL) as described in Materials and Methods. TNF-α and IL-18 concentrations were determined by electrochemiluminescence. Bars represent means ± SEM, n = 4. ***P < 0.001 vs. control. (B) LPMCs or IELs were stimulated for 15 minutes with either IL-6 or leptin. Immunoprecipitation for STAT-3 and subsequent Western blotting for phosphotyrosine was performed as described in Materials and Methods. Gastroenterology 2002 122, 2011-2025DOI: (10.1053/gast.2002.33631) Copyright © 2002 American Gastroenterological Association Terms and Conditions

Fig. 2 Evaluation of DSS-induced colitis and effect of leptin replacement. Ob/ob or WT mice were injected with leptin starting 5 days before the beginning of the 5-day DSS exposure, followed by a 5-day observation period. (A) Rectal bleeding and stool consistency were evaluated daily as described in Materials and Methods (ranging from 0 [healthy] to 4 [maximal disease activity]). Non–DSS-fed ob/ob and WT mice with or without leptin replacement are summarized as controls, because there were no differences between these experimental conditions. (B) At the end of the experimental period, the histologic score was determined as described in detail in Materials and Methods. Scores are mean ± SEM; n = 5 mice per group. *P < 0.05, **P < 0.01, ***P < 0.001 vs. DSS-fed ob/ob leptin-replaced, DSS-fed WT, and DSS-fed WT leptin-replaced mice. (C) Colon homogenate from the different experimental groups was evaluated for STAT-3 by Western blot as described in Materials and Methods. Gastroenterology 2002 122, 2011-2025DOI: (10.1053/gast.2002.33631) Copyright © 2002 American Gastroenterological Association Terms and Conditions

Fig. 3 Clinical score during chronic DSS treatment in ob/ob mice. WT and ob/ob mice were exposed to 2.5% DSS in drinking water for 5 days followed by 5 days of normal drinking water. This cycle was repeated 3 times, resulting in a 30-day experimental period. Body weight, stool consistency, and rectal bleeding were evaluated as described in Materials and Methods. Scores represent mean ± SEM; n = 5 mice per treatment group. *P < 0.05, **P < 0.01, and ***P < 0.001 vs. DSS ob/ob mice. Gastroenterology 2002 122, 2011-2025DOI: (10.1053/gast.2002.33631) Copyright © 2002 American Gastroenterological Association Terms and Conditions

Fig. 4 Histologic score after chronic DSS time course. At day 30, the end of the chronic DSS time course, a section of the transversing colon was taken for histologic analysis as described in Materials and Methods. (A) Histologic sections of DSS-fed WT and ob/ob mice with increasing magnifications. Because no significant difference between DSS-fed ob/ob and non-DSS controls could be detected, the controls are not shown. (B) Mean ± SEM of the histologic score for 5 sections per treatment group. ***P < 0.001 vs. DSS WT mice. Gastroenterology 2002 122, 2011-2025DOI: (10.1053/gast.2002.33631) Copyright © 2002 American Gastroenterological Association Terms and Conditions

Fig. 5 Spontaneous cytokine production in chronic DSS colon culture supernatant. WT and ob/ob mice were exposed to 2.5% DSS for 5 days followed by 5 days of normal drinking water. This cycle was repeated 3 times, resulting in a 30-day experimental period. Pieces of colon (1 cm2) were cultured for 24 hours as described in Materials and Methods, and cytokines were measured in the culture supernatant. Bars are mean ± SEM; n = 5. *P < 0.05, **P < 0.01, and ***P < 0.001 vs. DSS WT mice. Gastroenterology 2002 122, 2011-2025DOI: (10.1053/gast.2002.33631) Copyright © 2002 American Gastroenterological Association Terms and Conditions

Fig. 6 Chemokines and MPO levels in chronic DSS-induced colitis. WT and ob/ob mice were exposed to the chronic DSS experimental course as described in Materials and Methods. Spontaneous production of MIP-2 and MIP-1α in colon culture supernatant was determined by electrochemiluminescence. MPO activity was measured in colon homogenates as described in Materials and Methods. Means ± SEM are shown; n = 5. ***P < 0.001 vs. DSS WT mice. Gastroenterology 2002 122, 2011-2025DOI: (10.1053/gast.2002.33631) Copyright © 2002 American Gastroenterological Association Terms and Conditions

Fig. 7 Flow-cytometric analysis of IELs after chronic DSS time course. WT and ob/ob mice were either left untreated or were exposed to 2.5% DSS in drinking water for 5 days followed by 5 days of normal drinking water. This cycle was repeated 3 times, resulting in a 30-day experimental period. IELs and LPMCs were subsequently isolated as described in Materials and Methods. (A) The isolated IELs were restimulated with CD3ϵ in vitro for 4 hours and then stained for intracellular IFN-γ expression as described in detail in Materials and Methods. (B) The isolated LPMCs were stained for annexin V and propidium iodide as described in detail in Materials and Methods. The analysis shown is representative of 4 independent stainings performed per experimental group. Gastroenterology 2002 122, 2011-2025DOI: (10.1053/gast.2002.33631) Copyright © 2002 American Gastroenterological Association Terms and Conditions

Fig. 8 Lack of STAT-3 phosphorylation and COX-2 expression in the colons of DSS-treated ob/ob mice. WT and ob/ob mice were either left untreated or were exposed to 2.5% DSS in drinking water for 5 days followed by 5 days of normal drinking water. This cycle was repeated 3 times, resulting in a 30-day experimental period. At the end of the experiment, a colon section was homogenized in radioimmunoprecipitation assay buffer. Samples were analyzed by Western blot with antibodies specific for either (A) total STAT-3, (B) tyrosine phosphorylated STAT-3, or (C) COX-2. Gastroenterology 2002 122, 2011-2025DOI: (10.1053/gast.2002.33631) Copyright © 2002 American Gastroenterological Association Terms and Conditions

Fig. 9 ob/ob mice are protected against TNBS-induced colitis. TNBS was administered twice, at days 1 and 7, as described in Materials and Methods. (A) Percentage weight change in the different TNBS-treated and untreated groups. (B) Histologic score, evaluated as described in Materials and Methods. (C) Survival rate comparing TNBS-treated WT and ob/ob mice. (D) IFN-γ and MIP-2 release in the supernatant of colon cultures at the end of the experiment. (E) The isolated LPMCs were stained for annexin V and propidium iodide as described in detail in Materials and Methods. The analysis shown is representative of 4 independent stainings performed per experimental group. Results are mean ± SEM; n = 10 per experimental group; **P < 0.01 and ***P < 0.001 vs. TNBS WT mice. Gastroenterology 2002 122, 2011-2025DOI: (10.1053/gast.2002.33631) Copyright © 2002 American Gastroenterological Association Terms and Conditions