Modulation of amoebic hepatic abscess by the parasympathetic system.

The neuro-immune network, in which the vagus nerve is involved, provides feedback between its afferent branches for signalling central nervous system from sites of injury through cytokines and its efferent branches, which release acetylcholine, an anti-inflammatory neurotransmitter. For gain insight into the parasympathetic mechanisms participating in the inflammatory response in the liver, we studied the effects of a vagotomy on the innate immune response in hamsters with amoebic liver abscess. At 7 days post-infection, compared to the control, liver parasympathectomy resulted in a larger abscess size, a greater production of collagen fibres, fewer trophozoites, increased serum levels of IL-10 and IFN-γ and increased numbers of IL-10 and IFN-γ-positive cells in situ, with no change in the number of macrophages and NK cells. Data indicate that the vagotomy disrupted the inflammatory response, causing an increase in the response against infection, then could favour the innervation of the liver by the sympathetic nervous system and would then take the control of the immune response by stimulating the conversion of macrophages to epithelioid cells; and through increased IL-10 production would induce the hepatic stellar cells to become myofibroblast collagen producer cells, thus forming a barrier of collagen and blocking trophozoite migration.