Interactions of cytokines with the blood-brain barrier: implications for feeding

The blood-brain barrier (BBB) mediates interactions between the brain and the cytokines produced in the periphery. Some of these cytokines play significant roles in feeding behavior. This review will summarize various ways by which cytokines cross the BBB and discuss the implications of their transport systems in feeding. For simplicity of discussion, three categories of cytokines are discussed: (1). the proinflammatory cytokines TNFalpha, IFNgamma, IL1, and IL6; (2). the chemokines MIP-1, CINC-1 and IL8; and (3). other cytokines (LIF, CNTF, GM-CSF, FGF, EGF, and TGFalpha). The pharmacokinetics of barrier penetration, compartmental distribution, stability, and mechanism of passage (presence or absence of saturable transport) are summarized. Our understanding of cytokines interacting with the BBB is still growing; not only are more cytokines being studied, but also more details of the nature of the transport systems and how they affect feeding behavior are being explored.