Oral Intake of Combined Natural Immunostimulants Suppresses the 7,12-DMBA/ Croton Oil Induced Two-step Skin Carcinogenesis in Swiss Albino Mice.

Background: The immune system is critical in fighting cancer, so is it possible that the natural stimulation of this system can slow down or stop the evolution of cancer? Our in vivo study aimed to evaluate the protective effect of the combination of five types of immunostimulants, which are Beta-glucan and Arabinogalactan as polysaccharides and three mushroom extracts (Reishi, Maitake, and Shiitake), on 7,12-Dimethyl Benz[a]anthracene (DMBA)/ Croton oil-induced papilloma in Swiss albino mice.

Methodology: We used blood count analyses to estimate broadly the immunological reaction and biochemical techniques to determine the oxidative stress variations in the enzymatic activity of Superoxide dismutase (SOD), Catalase (CAT), and Glutathion peroxidase (GPx), which could have a preventive function against cancer development.

Results: The cutaneous application of the DMBA/Croton oil caused precancerous hyperplasia in squamous cells (papilloma) on the back of the mice. Tumor development was accompanied by a decrease in SOD and GPx activities. The treatment with the immunostimulants led to the total disappearance of the incidence of skin papillomas and also showed a nearly back to normal SOD activity but not CAT and GPx activities. The increase in the level of immune cells (lymphocytes, monocytes, and white blood cells) reflected a clear enhancement of the immune system activity.

Discussion: The healthy epidermis observed with treated mice simultaneously subjected to the cancerogenosis protocol suggests the inhibition of spinous cell proliferation leading to the total suppression of the hyperplasia. Moreover, the increase in the level of immune cells in this batch reflects an inflammatory reaction. Indeed, previous studies reported that immunostimulants, including Betaglucan involve a release of some inflammatory mediators who would be at the origin of its anticancer activity. Cancerogenesis has clearly disrupted the activities of the antioxidant enzymes, but the relationship between the two process is often complex. Bibliographic data led us to suggest that low catalytic activities of CAT and GPx observed in treated mice simultaneously subjected to the cancerogenesis protocol, would have induce an accumulation of H2O2 which has often been described as an inducer of cancer cells apoptosis.

Conclusion: Immunostimulants used in our study could have an effective protective effect against skin carcinogenesis via the enhancement of the global function of the immune system and modulation of the antioxidant defense.

Keywords: Immunostimulants, Beta-glucan, Arabinogalactan, Reishi, Maitake, Shiitake, DMBA, Croton oil, Oxidative stress, Carcinogenesis.

Abbreviations: C, control group; Dc, drug control group; Pc, positive control group; St, sick treated group;DMBA, 7,12 Dimethyl Benz[a]anthracene; NK, natural killer; CAT, catalase; SOD, superoxide dismutase, GPx, glutathione peroxidase; IS, immunostimulants; WBC, White blood cells; LY, Lymphocytes; MO, Monocytes; ROS, Reactive oxygen species; ONAB, Office national des aliments de bétail.