In recent years, studies on SZ bodily fluids have consistently reported increased numbers of TLR4-positive monocytes and elevated TLR4 expression in the peripheral blood of schizophrenia patients (149, 153–155), suggesting that TLR4 upregulation is a key factor in the immunopathological process of schizophrenia. This evidence concerns the gene TLR4 and schizophrenia.