TLR4 and diabetic kidney disease: Studies have shown that TLR4 expression is up-regulated in human DKD renal tissue, and gut microbiota-derived circulating LPS binds to TLR4, activates the nuclear factor kappa-B (NF-κB) signaling pathway, and up-regulates the expression of nucleotide-binding oligomeric domain-like receptor protein (NLRP) 3 in renal epithelial cells mediated by TNF-α and IL-12.