Inhibitory Effect of Bifidobacterium Iongum Cultures on the Azoxymethane-Induced Aberrant Crypt Foci Formation and Fecal Bacterial  -Glucuronidase

Abstract

Epidemiologic and experimental studies suggest that consumption of fermented milk products and lactic bacterial cultures that are used to ferment the dairy products, decrease the incidence of certain types of cancer. The present study was designed to determine the effect of lyophilized cultures of Bifidobacterium longum (B. longum), a lactic bacteria, on the azoxymethane (AOM)-induced preneoplastic lesions such as aberrant crypt foci (ACF) formation in the colon and on fecal bacterial beta-glucuronidase activity in male F344 rats. At 5 weeks of age, groups of animals were fed the AIN-76A (control) and the experimental diets containing 1.5% and 3% lyophilized cultures of B. longum. At 10 weeks of age, all animals received sc injection of AOM dissolved in normal saline at a dose rate of 20 mg/kg body wt, once weekly for 2 weeks. The animals were necropsied 6 weeks after the last AOM injection, and the ACF were visualized under light microscopy in the formalin-fixed, unsectioned methylene blue-stained colons where they were distinguished by their increased size, more prominent epithelial cells, and pericryptal space. The cecal contents were analyzed for bacterial beta-glucuronidase activity. The feeding of lyophilized cultures of B. longum significantly inhibited the ACF formation (53%) and the crypt multiplicity in the colon. A significant decrease in the fecal bacterial beta-glucuronidase was also observed in the animals fed the diets containing Bifidobacterium supplements as compared with control diet. These results demonstrate that B. longum in diet influences the metabolic activity of certain types of intestinal microflora that are involved in the production of beta-glucuronidase. Furthermore, the findings also suggest that B. longum supplements inhibit ACF formation, an early preneoplastic marker of malignant potential in the process of colon carcinogenesis.

Dairy products and colorectal cancer. A review of possible mechanisms and epidemiological evidence

“…may act against the development of aberrant crypt foci (ACF) in the colon of rats (Abdelali et al, 1995;Kulkarni & Reddy, 1994). Studies in vitro have shown that lactic acid bacteria have a capacity to absorb mutagens from cooked foods (Zhang & Ohta, 1993).…”

Pharmacological and dietary agents for colorectal cancer chemoprevention: Effects on polyamine metabolism (Review)

“…These bacteria have been shown to possess antimutagenic and anticarcinogenic properties and data from epidemio-logical and experimental studies clearly indicate that ingestion of lactobacilli and bifidobacteria, or their fermented dairy products, reduce the risk of certain types of cancer and inhibit tumor growth (64,65). The postulated mechanisms involve alterations of luminal ph in the gut, production of antimicrobial compounds, competition for pathogen binding and receptor sites, competition for available nutrients and growth factors, stimulation of immunomodulatory cells, and production of lactase (66).…”

Commensal Microorganisms in Development of the Children Immune System and New Facilities of Probiotics Usage

“…Действие бифидобактерий на иммунную систему хорошо доказано. Оно состоит в увеличении продукции IgA [60], противоопухолевой активности [61], повышении интенсивности фагоцитоза [62], измене-нии цитокинового профиля [63], повышении активности естественных киллеров [6], активации созревания ден-дритных клеток с повышением содержания цитокинов ИЛ 10 и 12 [64], увеличении интенсивности синтеза интерферона ␣ [62], поляризации баланса T х1 /T х2 в сто-рону T х2 [23]. Одним из наиболее изученных видов бифидобактерий с пробиотическим эффектом является Bifidobacterium animalis lactis.…”