Neuroimmune interactions in the gut. Article six in the series

The gastrointestinal tract is faced with the task of digesting and absorbing nutrients from the lumen while simultaneously excluding the entry of noxious microbes and antigens into the body. The intestine is a heterogeneous tissue consisting of immune, neuroendocrine, and structural elements, and it is the action of these cells that facilitates the transport and barrier functions of the gut and imparts to it the plasticity to respond appropriately to 'environmental' changes. Control of gut function was believed to be exerted via the neuroendocrine system, but it is now apparent that immune cells also influence intestinal physiology, directly and by interaction with nerve cells. Here we review neuroimmune control of gut function, emphasizing interactions between systems that were traditionally viewed as functionally discrete. We will draw attention to strategic sites in the neuroimmune cascade that may be appropriate targets for new anti-inflammatory/antisecretory treatments.