Lipopolysaccharide (LPS) and outer bacterial membrane (LPS)

Lipopolysaccharide (LPS) is the primary structural component of the outer membrane of Gram-negative bacteria, serving as a critical permeability barrier that protects the cell from environmental stressors and antibiotics (NIH, 2023). It is a complex glycolipid consisting of three regions: the hydrophobic Lipid A, a core oligosaccharide, and a distal O-antigen polysaccharide (PubChem). Lipid A is the endotoxic moiety recognized by the human immune system via the Toll-like receptor 4 (TLR4) complex, initiating a potent pro-inflammatory cytokine response (PubMed, 2019). While this response is vital for pathogen clearance, excessive LPS-induced signaling can lead to systemic inflammation, sepsis, and life-threatening septic shock (StatPearls, 2023). In clinical practice, the outer membrane and LPS are targeted by 'last-resort' polymyxin antibiotics, which bind to Lipid A to physically disrupt membrane integrity (PubMed, 2017). Emerging therapeutic strategies focus on inhibiting the lipopolysaccharide transport (Lpt) pathway or neutralizing circulating LPS to prevent the lethal complications of endotoxemia (Nature, 2019).

Other names

EndotoxinLipid AO-antigenGram-negative outer membraneLPS-OM complex

Drugs targeting this component typically act by binding to the Lipid A moiety to displace stabilizing divalent cations (Ca2+ and Mg2+), leading to membrane disruption and cell lysis (StatPearls, 2023). Newer agents like Murepavadin inhibit the Lpt protein machinery (specifically LptD) responsible for transporting LPS from the inner membrane to the outer membrane (Nature, 2019).