Tehran University Medical Journal

Background: Regarding the immunomodulatory effects of lactobacillus bacteria, this study aimed to evaluate the effect of oral administration of Lactobacillus reuteri, as probiotic bacteria, on natural killer cell cytotoxicity and tumor-specific lymphocyte proliferation in Balb/c mice with breast adenocarcinoma.

Methods: A total of 30 female mice, aged 6- 8 weeks and with a weight of approximately 17- 19 g, were randomly divided into two groups of 15 mice. The case group received Lactobacillus reuteri at a dose of 2.7× 108 bacteria in half a milliliter of sterile phosphate buffer saline (PBS) and the control group only received PBS. The probiotic group received the regimen for two weeks prior to tumor transplantation, as they did for 30 days after transplantation with three-day intervals and durations of seven days. For the evaluation of natural killer cell cytotoxicity and also tumor-specific lymphocyte proliferation response, LDH and BrdU assays were performed respectively according to the manufacturers' instructions.

Results: The study showed that the mice in the case group which were receiving Lactobacillus reuteri had statistically significant differences in the replication of tumor -specific lymphocytes, natural killer cell cytotoxicity and delayed hypersensitivity responses Compared to the mice in the control group.

Conclusion: Daily consumption of probiotics seems to regulate the immune system and consequently it can be helpful in people with cancer. Moreover, consumption of probiotics in healthy individuals can also boost the efficiency of the immune system against a variety of abnormalities.

Background: Several reports indicate that the probiotics can increase body resistance against malignant tumors. The aim of this study is to evaluate the effect of Lactobaci-llus reuteri Persian type culture collection (PTCC) 1655 in preventing tumor growth, improving weight and survival rate in mice with breast cancer.
Methods: Twenty mice, the BALB/c at six weeks age, weighing approximately 17 gram were divided into two groups. Oral administration of 500 micro liters of Lactobacillus reuteri suspension performed for the first group 14 days before tumor transplantation. The second group (control) received the same volume of phosphate buffer saline (PBS). Then the mice had tumor transplantation surgery. Lactobacillus reuteri was prescribed in the first group in seven-day period and three-day interruption pattern. At the same time the second group (control) received PBS. This process was continued until 45 day. The tumor growth, histology and body weight were evaluated in both group and the mortality of mice was recorded.
Results: In the mice transplanted tumors that had received probiotics, tumor growth decreased in comparison with control group. In this group the body weight increased (P>0/05). In addition, the survival of these mice had significantly increased compared to control group (P=0.002). The evaluation of tumor tissue also showed increased immune system function in mice receiving the probiotic (P>0/05).
Conclusion: Lactobacillus reuteri can improve immune system function and have an important role to help treatment of cancer.