The Immunomodulatory And Anti-tumor Effects Of Burdock Fructooligosaccharide On Mice

Inulin and oligofructose are known to modulate immune functions and exert anti-tumor activities. The main sources of inulin and oligofructose that are used in the food industry are chicory and Jerusalem artichoke. As one of the immportant Compositae family plant, Burdock (Arctium lappa L, var. Herkules)'s roots are also abundant in inulin. A low-molecular-weight inulin-type oligosaccharide named as Burdock fructooligosaccharide (BFO) has been obtained from the roots and its structure characteristics have also been identified in our lab. BFO has a chemical structure similar to that of polyfructosides from the plants of Compositae family. Preliminary studies have shown that it can act as an inducer in the plant growth and promote the increase amount of bifidobacteria and the proliferation of murine splenocytes in vitro. These studies suggest that BFO are prebiotics and immuno-stimulating agents. However, the immunomodulatory effects of BFO are rarely documented. Therefore, to understand its immunomodulatory effects will contribute to its further reseach and developmemt.In the present study, we first probed into a low-cost method to exclude the endotoxin contamination. Then the immunomodulatory effects of BFO on mice were investigated in vitro and in vivo. The anti-tumor activities of BFO on S180 mice were also studied.The exclusion and determination of endotoxin contamination in Burdock fructooligosaccharideGram-negative bacterial LPS (i.e., endotoxin) is a main contaminant in many biochemical materials prepations which exhibit a potential interference by its innate stimulatory properties. In our study, DEAE-cellulose was used to exclude the LPS-like contaminants in BFO. We demonstrated that DEAE-cellulose was a suitable method to exclude endotoxin contaminant in BFO, with the LPS-content decreasingas low as 25 folds and the recovery rate reaching 70%.Effects of BFO on in vitro immunomodulatory activity of mouse immune systemImmunomodulatory activity of BFO was examined on the proliferation response of murine splenocytes and the macrophages in vitro. Lymphocytes play a pivotal role in the regulation of immune responses. And its rapid proliferation is crucial in the assessment of lymphocyte functions. Our study observed that treatment with 25-1000 μg/ml BFO enhance the proliferation of splenocytes in a dose-dependent manner, and the maximal activity was obtained at the concentration of 1000 μg/ml. Also, 25-1000 μg/ml BFO dose-dependently enhance ConA-induced splenocyte proliferation. It was suggested that BFO has a direct effect on T cell function and might influence T cell-induced cellular immunity.Macrophages are important cells which play key roles in immune system defense, including the phagocytosis of pathogens, the production of many cytokines, and the proteolytic processing and presentation of foreign antigens. Nitric oxide (NO) produced during macrophage activation is a new type of effector molecular which involved in many physiological and pathological processes such as nonspecific host defense, antimicrobial and anti-tumor activities and cytotoxic effcet. The results showed that BFO had no direct effect on the production of NO in murine peritoneal macrophages. Different effects were obtained when BFO treated with LPS. BFO exhibited inhibitory effects in low concentration while the contrary effcets in high level.Acid phosphatase is one kind of lysosomal enzyme produced by activated macrophages which is also an important indicate in the assessment of macrophage function. BFO can significantly increase the acid phosphatase activity at a concentration of 50-1000 μg/ml in a dose-dependent fashion. BFO (100 μg/ml) can markedly promote the acid phosphatase activity compared to a control (p<0.01). The immunomodulatory in vivo and anti-tumor activity of Burdock fructooligosaccharideThe modulation of BFO on the immune system in normal mice, cyclophosphamide (CTX) -induced immunosuppressive mice and S180-bearing mice was investigated. The phagocytosis, NO production and acid phosphatase activities in macrophage, the level of serum hemolysin, B cell mediated haemolytic effect and lymphocyte proliferation were tested to investigate the cellular and humoral immunity in animal models.The mice were treated p.o. with BFO (100, 250,500 and 1000 mg/kg/day) for 10 days. Our study showed that BFO could significantly increase the phagocytosis, the release of NO and the acid phosphatase activity in macrophage, while the level of serum hemolysin, B cell mediated haemolytic effect and spleen lymphocyte proliferation activity were unchanged in normal mice. However, naearly all the immune parameters mentioned above were improved in CTX-induced immunosuppressive mice, suggesting that BFO can antagonize the immuosuppression induced by CTX. We also found that BFO can significantly intensify the macrophage phagocytosis and the NO production in S180-bearing mice. These results suggest that BFO has a highly significant effect on the improvement of immune system in normal, immunosuppressive and tumor-bearing mice.Then, we investigated the antitumor effects of BFO in S180-bearing mice. BFO inhibited the growth of S180 tumor only at a high dose of 1000 mg/kg/day when treated after tumor inoculation, with inhibitory rate 19.01%. In contrast, when administrated to the mice for 7 days before tumor inoculation at a dose of 250, 500 and 1000 mg/kg/day, BFO could significant exhibt antitumor activity. The inhibitory rate was 24.26%, 25.53% and 33.14%, respectively.The results demonstrated that BFO exerts strong immunomodulatory and anti-tumor effects on experimental mice which may involve in the augmentation of lymphocyte and macrophage activities. Our research may make contribution to the theoretic basis for the development of BFO as a new Biological response modifier (BRM).