Lactobacillus bulgaricus inhibits colitis-associated cancer via a negative regulation of intestinal inflammation in azoxymethane/dextran sodium sulfate model

Figure 1 Lactobacillus bulgaricus inhibits tumor progression in azoxymethene/dextran sulfate sodium-exposed mice. A: Prior to tumor induction, mice were treated 3 times with PBS or the probiotic by gavage (0.2 mL/mouse) for one week. After that, colitis-associated cancer was induced by intraperitoneal injection of a single dose of azoxymethene (AOM), followed by 3 cycles of 2, 5% dextran sulfate sodium (DSS) in drinking water for one week and normal drinking water for 2 wk; B: After euthanasia at 12th week, colons were longitudinally opened, washed and examined for multiplicity; C: Total tumor volume; D: Mean tumor volume; E: The dimensions of colorectal tumors were measured with pachymeter and the volumes calculated as: (Width)² × length / 2. Illustrative and endoscopic images of AOM/DSS-induced tumors. ^aP < 0.05; ^eP < 0.001 vs controls. AOM: Azoxymethane; Ctrl: Controls; DSS: Dextran sulfate sodium; Lb: Lactobacillus bulgaricus; PBS: Phosphate-buffered saline.

Figure 2 Lactobacillus bulgaricus attenuates intestinal inflammation in azoxymethene/dextran sulfate sodium-exposed mice. A: Relative body weight of azoxymethene/dextran sulfate sodium-induced mice treated or not with probiotic; B: Disease score determined by a scoring system based on clinical signs, such as weight loss, humid perianal region, presence of diarrhea, blood in the stool or perianal region, hyporreativity and piloerection; C: Colon length was determined using graduated images processed in ImageJ; D: Illustrative imagens of colon extension. Results are expressed as mean ± EPM. ^aP < 0.05, ^bP < 0.01, ^eP < 0.001 vs controls. Ctrl: Controls; Lb: Lactobacillus bulgaricus.

Figure 3 Lactobacillus bulgaricus regulates the production of intestinal proinflammatory cytokines in azoxymethene/dextran sulfate sodium-exposed mice. Segments of the colon which did not present tumors (inflamed colon) were homogenized and the levels of TNF-α, IL-6, IL- 1β, IL-17, IFN-γ e IL-23 per gram of tissue were determined by ELISA (n = 10 mice per group). Results expressed as mean ± SEM. ^aP < 0.05, ^bP < 0.01, ^eP < 0.001 vs controls. Ctrl: Controls; Lb: Lactobacillus bulgaricus.

Figure 4 Lactobacillus bulgaricus regulates the production of tumors proinflammatory cytokines in azoxymethene/dextran sulfate sodium-exposed mice. Tumor tissues were homogenized and the concentration of TNF-α, IL-6, IL- 1β, IL-17, IFN-γ e IL-23 per gram of tissue (colon) were determined by ELISA (n = 10 mice per group). Results expressed as mean ± SEM. ^aP < 0.05, ^bP < 0.01, ^eP < 0.001 vs controls. Ctrl: Controls; Lb: Lactobacillus bulgaricus.