lipopolysakkaridista

Lipopolysaccharide (LPS), also known as lipoglycan, is a large molecule found in the outer membrane of Gram-negative bacteria. It is composed of three parts: lipid A, a core polysaccharide, and the O antigen. Lipid A is the hydrophobic anchor that embeds LPS within the bacterial membrane. The core polysaccharide is a chain of sugars attached to lipid A, and it can vary in structure. The O antigen is a repeating unit of sugars that extends outwards from the core polysaccharide and is highly variable between different bacterial species and strains, acting as a major surface antigen.

LPS plays a crucial role in the structural integrity of the Gram-negative bacterial outer membrane, contributing to its permeability barrier. It is also a potent immunostimulant. When LPS is released from the bacterial cell wall, for instance, during bacterial lysis or infection, it can interact with host immune cells. This interaction, primarily mediated by Toll-like receptor 4 (TLR4), triggers a strong inflammatory response. This response can be beneficial in fighting infection, but excessive or uncontrolled inflammation can lead to septic shock, a life-threatening condition characterized by a sudden drop in blood pressure. The O antigen portion of LPS is often the target of antibodies, contributing to the development of adaptive immunity against bacterial infections.