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
This work is licensed under a Creative Commons Attribution 4.0 International License.
Based on a work at https://cwoer.ccbcmd.edu/science/microbiology/index_gos.html.
Last updated: Feb., 2021
Please send comments and inquiries to Dr.
Gary Kaiser