Fig. 5: Harmful Effects of Lipopolysaccharide (LPS; Endotoxin)
Released from the Gram-Negative Cell Wall

The lysis of Gram-negative bacteria causes them to release lipopolysaccharide (LPS; endotoxin) from the outer membrane of their cell wall. The LPS binds to a LPS-binding protein circulating in the blood and this complex, in turn, binds to a receptor molecule (CD14) found on the surface of body defense cells called macrophages. This is thought to promote the ability of the pattern recognition receptor (PRR) called TLR-4 to respond to the LPS, triggering the macrophage to release various defense regulatory chemicals called cytokines, including IL-1, IL-6, IL-8, TNF-alpha, and PAF. The cytokines then bind to cytokine receptors on target cells stimulating the production of inflammatory mediators such as prostaglandins and leukotrienes as well as activating both the complement pathways and the coagulation pathway. Excessive production of clotting factors may lead to ARDS and DIC while an overproduction of prostaglandins, leukotrienes, and complement proteins can damage the vascular endothelium resulting in shock and MSOF.

(LPS, lipopolysaccharide; IL-1, interleukin-1; IL-6, interleukin-6; IL-8, interleukin-8, TNF-alpha, tumor necrosis factor-alpha; PAF, platelet-activating factor; ARDS, acute respiratory distress syndrome; DIC, disseminated intravascular coagulation; MSOF, multiple system organ failure.)

Illustration of The Harmful Effects of Lipopolysaccharide (LPS; Endotoxin) Released from the Gram-Negative Cell Wall.jpg by Gary E. Kaiser, Ph.D. Professor of Microbiology, The Community College of Baltimore County, Catonsville Campus
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Last updated: August, 2018
Please send comments and inquiries to Dr. Gary Kaiser