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The effect of orally administered glycogen on anti-tumor activity and natural killer cell activity in mice
Ryo Kakutani1, Yoshiyuki Adachi, Hideki Kajiura
1Institute of Health Sciences, Ezaki Glico Co., Ltd., 4-6-5, Utajima, Nishiyodogawa-ku, Osaka 555-8502, Japan. kakutani-ryou@glico.co.jp
Abstract:
Natural killer (NK) cells, innate immune effectors that mediate rapid responses to various antigens, play an important role in potentiating host defenses through the clearance of tumor cells and virally infected cells. By using enzymatically synthesized glycogen (ESG) with the same characteristics as natural glycogen, we examined whether orally administered glycogen enhances the innate defense of tumor-implanted mice and the cytotoxicity of NK cells. Oral administration of ESG led to the suppression of tumor proliferation and the prolongation of survival times of tumor-bearing mice. Splenic NK activities of BALB/c mice treated orally with ESG were significantly higher than those of water-treated mice, which were used as a negative control. In addition, intraduodenal injections of ESG gradually and markedly lowered splenic sympathetic nerve activity, which has an inverse correlation with NK activity. Furthermore, ESG activated Peyer's patch cells to induce the production of macrophage inflammatory protein-2 (MIP-2), interleukin-6 (IL-6), and immunoglobulin A (IgA) from these cells. These results demonstrated that orally administrated glycogen significantly enhanced the cytotoxicity of NK cells by acting on Peyer's patch cells and autonomic nerves, and eventually induced the potentiation of host defenses. We propose that glycogen functions not only as an energy source for life support but also as an oral adjuvant for immunopotentiation.
Insights
Oral glycogen administration boosts natural killer (NK) cell activity and enhances host defense against tumors. This study shows glycogen acts as an oral adjuvant, improving immune responses.
Area of Science:
- Immunology
- Cellular Biology
- Pharmacology
Background:
- Natural killer (NK) cells are crucial innate immune cells for clearing tumor and virally infected cells.
- Glycogen is a primary energy source, but its role in immune modulation is less understood.
Purpose of the Study:
- To investigate the effects of orally administered enzymatically synthesized glycogen (ESG) on innate immunity and NK cell cytotoxicity.
- To determine if glycogen can enhance host defense mechanisms against tumor progression.
Main Methods:
- Mice with tumors were treated with ESG orally.
- Splenic NK cell activity was measured.
- Sympathetic nerve activity and Peyer's patch cell activation were assessed.
- Production of inflammatory mediators and IgA was analyzed.
Main Results:
- Oral ESG administration suppressed tumor growth and increased survival rates in tumor-bearing mice.
- ESG significantly enhanced splenic NK cell activity compared to controls.
- ESG reduced splenic sympathetic nerve activity and activated Peyer's patch cells.
- Activated Peyer's patch cells produced MIP-2, IL-6, and IgA.
Conclusions:
- Orally administered glycogen enhances NK cell cytotoxicity through Peyer's patch cell activation and modulation of autonomic nerves.
- Glycogen acts as an oral adjuvant, potentiating host defense mechanisms beyond its role as an energy source.
- Glycogen holds potential for immunomodulatory therapies.
