TLR4 and Parkinson disease: Given that exposure of cultured IECs to LPS from enteropathogenic Escherichia coli (E. coli) increases both TLR2 and TLR4 expression [85] and that stimulation of IECs with peptidoglycans causes TLR2 trafficking from apical to basolateral membranes [84], it is possible that a dysbiotic gut microbiome alters intestinal TLR2 levels and thus contributes to early gut dysfunction in people with PD.