When the gut reacts, Toll-like receptor 2 and Toll-like receptor 4 are activated by recognizing bacterial DNA in the gut, the expression of Toll-like receptor 2 and Toll-like receptor 4 in the gut is significantly higher than in healthy people (82), and abnormal expression of their receptors can accelerate the occurrence of Parkinson’s disease (83). This evidence concerns the gene TLR4 and Parkinson disease.