Caffeine and its main targets of colorectal cancer

Figure 9 General effects of caffeine on lymphocytes and macrophages. Four types of immune cells can be influenced by caffeine. In T cells, cAMP and Ca²⁺ can be modulated by caffeine through the binding of adenosine receptors, modulating norepinephrine and inhibiting phosphodiesterase. In B cells, caffeine can influence the immune response through interacting with Ca²⁺. In macrophages, caffeine can both inhibit and activate toll-like receptor-mediated inflammation by modulating Ca²⁺ and binding to adenosine. Furthermore, in natural killer cells, caffeine exerts a dual function on its activation. When it acts on A1R, it inhibits. When it acts on A2R, it induces. Moreover, by stimulating norepinephrine , caffeine can promote the mobilization of natural killer cells. AR: Adenosine receptors; NE: Norepinephrine; PDE: Phosphodiesterase; TLR: Toll-like receptor; NK: Natural killer; IL: Interleukin.