Impact of dietary components on NK and Treg cell function for cancer prevention

Abstract

An important characteristic of cancer is that the disease can overcome the surveillance of the immune system. A possible explanation for this resistance arises from the ability of tumor cells to block the tumoricidal activity of host immune cells such as natural killer (NK) cells by inducing the localized accumulation of regulatory T (Treg) cells. Evidence exists that components in commonly consumed foods including vitamins A, D, and E, water-soluble constituents of mushrooms, polyphenolics in fruits and vegetables, and n-3 fatty acids in fish oil can modulate NK cell activities, Treg cell properties, and the interactions between those two cell types. Thus, it is extremely important for cancer prevention to understand the involvement of dietary components with the early stage dynamics of interactions among these immune cells. This review addresses the potential significance of diet in supporting the function of NK cells, Treg cells, and the balance between those two cell types, which ultimately results in decreased cancer risk.

Keywords: cancer prevention; dietary components; natural killer cells; regulatory t cells.

Conflict of interest statement

Disclosure of Potential Conflicts of Interest

The authors declare no conflict of interest.

Published 2015. This article is a U.S. Government work and is in the public domain in the USA.

Figures

Figure 1

Dietary components modulate tumoricidal activity of NK cells by three distinct processes including receptor-ligand interactions, the release of cytokines, and the secretion of lytic enzymes. Specific examples are discussed in the text under section 2. This figure does not reflect the actual size of cells.

Figure 2

A naïve T cell can be differentiated into any Th effector cells depending on the cytokines released into the microenvironment. Dietary constituents including vitamin A metabolite retinoic acids, vitamin D, and polyphenolics are shown to inhibit the expression of various cytokines such as IL4, IL6, and IL12, and thereby increase TGFβ-dependent peripheral Treg induction.

Figure 3

Nutrients are metabolized to small molecular weight compounds which increase tumoricidal activity of NK cells and induce the controlling properties of iTreg cells. The modulating effects of nutrients on the expression and function of iTreg cells are critical to prevent autoimmunity and allergy. When the gut epithelium is transformed by external stimuli including reactive oxygen species (ROS), pathogens, and inflammatory molecules, iTreg cells lose their stability and function. However, the role of these iTreg cells in tumor microenvironment remains unclear.