LPS, from Escherichia coli O55:B5

LPS (from E. coli O55:B5; CAS 93572-42-0) is an S (smooth)-type lipopolysaccharide endotoxin extracted from Escherichia coli (E. coli O55:B5) and is a TLR4 agonist with well-defined pyrogenicity and serotype specificity. It consists of three parts: O antigen, core oligosaccharide, and lipid A, and is an important component of the outer membrane of Gram-negative bacterial cell walls. This LPS activates the TLR4 signaling pathway in immune cells, triggering a cascade release of cytokines and inflammatory mediators, inducing in vitro cell activation, inflammatory responses, and endotoxin-like shock reactions, and is commonly used to establish sepsis and acute lung injury animal models. It is also used to establish in vitro inflammation models in monocytes/macrophages, endothelial cells, and immune cells (e.g., detection of NO, cytokines, and NF-kappaB/MAPK activation), and can serve as a positive control for endotoxin (LAL) assays and for screening the effects and mechanisms of anti-inflammatory/immunomodulatory drugs. Its stable activity and reproducible responses make it suitable for evaluating the role of endotoxin in various inflammation-related pathological processes such as liver disease, nerve injury, and skeletal muscle insulin resistance.