Intermittent Fasting Reduces Intestinal Inflammation in Dextran Sulfate Sodium-Induced Colitis of Mice

Abstract

Inflammatory bowel disease (IBD), comprising ulcerative colitis (UC) and Crohn's disease (CD), is a chronic condition impacting both the gastrointestinal tract and the immune system. Intestinal inflammation and epithelial injury are the pathological features of IBD. Recent studies have reported that some strategies of dietary restriction (DR) can regulate immune system, correct the immune disorders, and improve some immune-associated diseases such as IBD. However, as a form of DR, the effect of intermittent fasting (IF) on the IBD remains unknown. In this study, we investigated the therapeutic efficacy of two cycles of IF on the IBD mouse model induced by dextran sulfate sodium (DSS). It was found that two cycles of IF significantly decreased the score of the disease activity index (DAI) and alleviated the IBD-related symptoms. In addition, IF reversed the shortening of colon length mediated by DSS, significantly increased the number of colonic crypts, and decreased the colonic histological score. Furthermore, the proportion of CD4⁺ T cells in both the spleen and mesenteric lymph node was reduced by IF treatment. The expression of serum pro-inflammatory cytokines IL-1β, TNF-α, and IL-6 was restrained by IF intervention. Moreover, IF administration significantly reduced the number of leukocytes and macrophages infiltrating around the crypt base in the colon. In conclusion, these results demonstrated that IF administration can alleviate the symptoms and pathology of IBD in the DSS-induced IBD mouse model by reducing the intestinal inflammation.

Keywords: inflammation; inflammatory bowel disease; intermittent fasting; intestine.

FIGURE 1

IF improves the symptoms associated with IBD and reduces DAI in the mouse model of IBD. (A) The protocol of the experiment for managing drinking and feeding in three groups. (B) The DAI score for three groups that comprise the score of stool consistency and hemoccult test during cycles 2 and 3: control group (n = 6), DSS group (n = 5), and DSS + IF group (n = 5). (C) DAI scores for assessing weight reduction. (D) DAI scores for assessing stool consistency. (E) DAI scores for assessing the bleeding in stool. The period of DSS treatment is represented by the red shading in (B–E), while the blue shading indicates the period of IF application. The data are displayed as the mean ± SEM; The * indicates a significant distinction between the DSS and DSS + IF groups. *p < 0.05; **p < 0.01; ***p < 0.001.

FIGURE 2

IF maintains colon length and reduces colonic inflammatory injury. (A) The representative colon images of the three groups. (B) The lengths of the colon were measured in the control group (n = 6), DSS group (n = 5), and DSS + IF group (n = 5). (C) The colon tissue was stained with HE, and images were captured at a magnification of 20×. The scale bars for the upper panels are 50 μm, and for the lower panels, they are 20 μm. (D) The colonic crypts number varied among the control group (n = 6), DSS group (n = 5), and DSS + IF group (n = 5). (E) The histological scores were evaluated on colon in the control group (n = 6), DSS group (n = 5), and DSS + IF group (n = 5). The data are reported as mean ± SEM; *p < 0.05; **p < 0.01; ***p < 0.001; ****p < 0.0001.

FIGURE 3

IF reduces T cells proportion in the spleen and mesenteric lymph node. (A) The outcomes of spleen T cells proportion in the control group (n = 6), DSS group (n = 5), and DSS + IF group (n = 5) were detected by flow cytometry. (B) The comparison of spleen CD4⁺ T cell proportion among the control group, DSS group, and DSS + IF group. (C) The comparison of spleen CD8⁺ T cell proportion among the control group, DSS group, and DSS + IF group. (D) The outcomes of mesenteric lymph node T cell proportion in the control group (n = 6), DSS group (n = 5), and DSS + IF group (n = 5). (E) The comparison of mesenteric lymph node CD4⁺ T cells proportion among the control group, DSS group, and DSS + IF group. (F) The comparison of mesenteric lymph node CD8⁺ T cell proportions among the control group, DSS group, and DSS + IF group. The data are reported as mean ± SEM; **p < 0.01; ***p < 0.001.

FIGURE 4

IF restrains the expression of pro‐inflammatory cytokines in the serum. (A) The level of serum IL‐1β (pg/mL) in the control group (n = 6), DSS group (n = 5), and DSS + IF group (n = 5). (B) The level of serum TNF‐α (pg/mL) in the control group (n = 6), DSS group (n = 5), and DSS + IF group (n = 5). (C) The level of serum IL‐6 (pg/mL) in the control group (n = 6), DSS group (n = 5), and DSS + IF group (n = 5). (D) The level of serum IFN‐γ (pg/mL) in the control group (n = 6), DSS group (n = 5), and DSS + IF group (n = 5). The data are reported as mean ± SEM; **p < 0.01; ***p < 0.001; ****p < 0.0001.

FIGURE 5

IF reduces immune cell infiltration around colonic crypt bases. (A) The colonic immunofluorescence staining representative images for CD45⁺ cells in the control group (n = 6), DSS group (n = 5), and DSS + IF group (n = 5). (B) The quantitation of CD45⁺ cells around colonic crypt bases. (C) The colonic immunofluorescence staining representative images for F4/80⁺ cells in the control group (n = 6), DSS group (n = 5), and DSS + IF group (n = 5). (D) The quantitation of F4/80⁺ cells around colonic crypt bases. The data are reported as mean ± SEM; *p < 0.05; ***p < 0.001; ****p < 0.0001. The images for immunofluorescence staining were captured at 20× magnification. The scale bar measures 50 μm.