#B187 Prebiotic Treatment Modulates the Gut-Associated Immune System and Decreases AOM-Induced Colon Carcinogenesis in F344 Rats. Monica Roller,1 A. P. Femia,2 Jan Van Loo,3 Giovanna Caderni,2 Gerhard Rechkemmer,1 Bernhard Watzl.1 Federal Research Centre for Nutrition,1 Karlsruhe, Germany, University of Florence,2 Florence, Italy, Orafti, S.A.,3 Tienen, Belgium. Studies suggest that probiotics (PRO) modulate the immune system and decrease colon cancer risk. For prebiotics (PRE), however, no data are available on their immunomodulatory effects. Further, no study so far has looked at the effects of the combined application of PRO and PRE (synbiotics, SYN) on the gut-associated lymphoid-tissue (GALT) and on colon carcinogenesis within the same animal. In the present study, the effects of PRO, PRE and SYN on the GALT and on colon tumorigenesis of rats treated orally with the carcinogen azoxymethane (AOM) was investigated. Male F344 rats received for 32 wks a high fat diet (23% w/w corn oil) as the basic diet supplemented with PRO (B. lactis BB12 and L. bulgaricus GG, each 5x108 cfu/g diet), PRE (RAFTILOSE Synergy1, 10% of the diet. This is a 1:1 mixture of linear beta(2-1)fructans with average chain length of 4 with degree ofpolymerisation (DP) ranging between 3 and 7)and linear beta(2-1)fructans with average chain length of 25, DP ranging between 12 and 65. These prebiotics are extracted from the chicory root), or SYN. Rats were treated with AOM (15 mg/kg s.c., twice) 10 days after the beginning of the dietary treatment. Immune cell suspensions were prepared from mesenteric lymph nodes (MLN) and Peyer’s patches (PP) and the following immune parameters were measured: Lytic activity of natural killer (NK) cells, lymphocyte proliferation and cytokine secretion capacity (IL-10, IFN-g). PRE supplementation enhanced NK cell activity (PP), IL-10 secretion (PP, MLN), as well as IFN-gsecretion (PP). SYN significantly increased NK cell activity (PP), IL-10 secretion (PP), while lymphocyte proliferation (PP) was decreased. Rats treated with PRE or SYN had a significantly lower number of tumors (adenomas and cancers) compared with PRO or controls. In conclusion, PRE treatment of AOM-exposed rats stimulated the GALT primarily enhancing anti-tumor defense mechanisms (NK cell activity, IFN-g) which coincided with reduced tumor numbers in the colon. This further suggests that the immune system of the gut may affect colon carcinogenesis. This research is supported by the European Union - DG Research (SYNCAN-QLKI-1999-00346). Frontiers in Cancer Prevention Research, 2003 AACR Abstract #C146 Frontiers in Cancer Prevention Res, 2003 Remember we are NOT Doctors and have NO medical training. This site is like an Encylopedia - there are many pages, many links on many topics. Support our work with any size DONATION - see left side of any page - for how to donate. You can help raise awareness of CAM.