Amebic Liver Abscess in Rat: Morphological Evidence of Innate Immune Modulation by the Sympathetic Nervous System

All organs of the immune system are innervated and almost all neurotransmitter receptors are present on immune cells. We studied the effects of sympathetic innervation in the development of amebic liver abscess (ALA) in rats. Our results showed that lack of sympathetic innervation promote a decrease in size of ALA. We found scarce amoebas, increased the number of neutrophils and a few collagen fibers surrounding the abscess, meanwhile in control group, we observed abscesses areas with typical necrosis including trophozoites and neutrophils. Macrophages were differentially distributed surrounding abscess area in control and vehicle groups, but equally located in and outside of the abscesses in sympathectomized rat. No significant differences were observed on NK cells in analysed groups. In cytokines quantification studies, we observed down-expression of IFN-gamma and TNF-alpha, moreover, we found overexpression of IL-10 in sympathectomized and ALA group. In conclusion, our results suggest that elimination of sympathetic nerve fibers in a model rat of amebic liver abscess induces reduction of the innate immune response and presence of amebas through the liver at seven days post-inoculation.