A Probiotic Strain of L. Acidophilus Reduces DMH-Induced Large Intestinal Tumors in Male Sprague-Dawley Rats

Abstract

Probiotic bacteria strains were examined for their influence on 1,2-dimethylhydrazine (DMH)-induced intestinal tumors in 100 male Sprague-Dawley rats. Lactobacillus acidophilus (Delvo Pro LA-1), Lactobacillus rhamnosus (GG), Bifidobacterium animalis (CSCC1941), and Streptococcus thermophilus (DD145) strains were examined for their influence when added as freeze-dried bacteria to an experimental diet based on a high-fat semipurified (AIN-93) rodent diet. Four bacterial treatments were compared: L. acidophilus, L. acidophilus + B. animalis, L. rhamnosus, and S. thermophilus, the bacteria being added daily at 1% freeze-dried weight (10(10) colony-forming units/g) to the diet. Trends were observed in the incidence of rats with large intestinal tumors for three treatments: 25% lower than control for L. acidophilus, 20% lower for L. acidophilus + B. animalis and L. rhamnosus treatments, and 10% lower for S. thermophilus. Large intestinal tumor burden was significantly lower for treated rats with L. acidophilus than for the control group (10 and 3 tumors/treatment group, respectively, p = 0.05). Large intestinal tumor mass index was also lower for the L. acidophilus treatment than for control (1.70 and 0.10, respectively, p < 0.05). Other treatments showed no statistically significant change from control for these indexes of tumorigenesis. For rats fed L. acidophilus, no adenocarcinomas were present in the colons. Pulsed-field gel electrophoresis of bacterial chromosomal DNA fragments was used to differentiate introduced (exogenous) bacterial strains from indigenous bacteria of the same genera present in the feces. Survival during gut passage and displacement of indigenous lactobacilli occurred with introduced L. acidophilus and L. rhamnosus GG during the probiotic treatment period. However, introduced strains of B. animalis and S. thermophilus were not able to be isolated from feces. It is concluded that this strain of L. acidophilus supplied as freeze-dried bacteria in the diet was protective, as seen by a small but significant inhibition of tumors within the rat colon.

Cell Surface-Associated Elongation Factor Tu Mediates the Attachment of Lactobacillus johnsonii NCC533 (La1) to Human Intestinal Cells and Mucins

“…In addition, immunomodulation studies performed on HT29 cells showed that EF-Tu recombinant protein can induce a proinflammatory response in the presence of soluble CD14. Our in vitro results indicate that EF-Tu, through its binding to the intestinal mucosa, might participate in gut homeostasis.Probiotic bacteria, mainly lactic acid bacteria and bifidobacteria, have been shown to have beneficial effects on the immune defenses and to alleviate or prevent diverse intestinal disorders (3,4,16,25,27,30,39,42,47). Several in vitro studies have shown that one of them, Lactobacillus johnsonii NCC533 (La1), is able to bind to epithelial cell lines (5,8,9,21) and can induce the secretion of different cytokines in coculture systems (9, 24).…”

A Probiotic Strain of Bacillus polyfermenticus Reduces DMH Induced Precancerous Lesions in F344 Male Rat

“…23) Similar results have been observed in the colons of rats or mice treated with other probiotics administered during the post-initiation phase of DMH-induced carcinogenesis. [24][25][26] Abdelali et al (1995) determined that rats administered the colon carcinogen, DMH, and fed on diets containing 6ϫ10 9 cfu/d of Bifidobacterium longum evidenced a 63% reduction in the total number of aberrant crypts per colon, relative to a control diet containing no bifidobacteria. 24) As DNA damage has been implicated as the initial step in chemical carcinogenesis, the blocking of DNA damage should constitute the first line of defense against cancer induced by carcinogens.…”

Probiotics: A Comprehensive Review of Their Classification, Mode of Action and Role in Human Nutrition

“…In animal models, lactobacillus has been shown to bind dietary carcinogens [38] and decrease development of tumors in the colon after carcinogen challenge [39,40]. Preliminary research also suggests that lactobacilli, especially L. plantarum, can reduce the severity of chemotherapy-induced enterocolitis [41].…”