The level of LPS markers in the colon and plasma of PD patients is significantly increased, which results in the activation of a series of inflammatory reactions, manifesting as an increase in the T cell transport to the colonic mucosa and the number of toll-like receptor 4 (TLR4)-positive cells (such as dendritic cells and macrophages), which have been shown to mediate inflammation [123]. This evidence concerns the gene TLR4 and Parkinson disease.