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Effects of Endotoxin on Cells

Release time：

2024-09-09

Endotoxin: Endotoxin is a component of the cell wall of Gram-negative bacteria, called lipopolysaccharide (LPS). LPS is toxic to the host. Although endotoxin is tightly embedded in the cell wall, it is also continuously released into the surrounding environment - not only as a result of cell disintegration and death, but also during normal cell growth and division.

Endotoxin is not a protein and is therefore very heat-resistant. At 100 °C it is not destroyed even after heating for 1 hour; only heating at 160 °C for 2 to 4 hours, or boiling with strong alkali, strong acid or strong oxidants for 30 minutes, can destroy its biological activity. Unlike exotoxins, endotoxin cannot be detoxified into a toxoid by dilute formaldehyde solution; although injecting endotoxin into the body can produce a certain amount of specific immune products (called antibodies), such antibodies are weak in neutralizing endotoxin toxicity.

Effects of Endotoxin on Cell Culture

Cell Morphology

Endotoxin can alter cell appearance; for example, it changes the shape of hepatocytes and reduces their ability to take up hexose. When cells are cultured in medium containing endotoxin, obvious morphological changes occur, such as reduced cell size and decreased refractility.

Activation of Immune Responses

Endotoxin can bind to receptors on the cell membrane, triggering immune responses and activating inflammatory cells and the release of inflammatory factors within tissues. It may also trigger cellular inflammatory responses, affecting cell growth, health and experimental results.

Effects on Cell Function

Endotoxin significantly affects cell function, including altering cellular energy metabolism and protein synthesis. In addition, endotoxin can interfere with insulin signaling pathways, thereby affecting cellular energy metabolism and protein synthesis.

Effects on Cell Growth

Endotoxin has negative effects on cell growth and function, especially during cell culture, and may lead to erroneous conclusions in experiments. Toxicity varies considerably among different endotoxins and different cell lines.

Effects on Gene Expression

Endotoxin can stimulate white blood cell cultures to produce tissue factor, activate murine macrophages, and inhibit murine erythroid colony formation at extremely low levels, among a series of other indicators.

Effects on Transfection Efficiency

Endotoxin can have a major impact on the DNA transfection process of primary cells and sensitive cultured cells; high endotoxin levels compete with DNA for transfection reagents, reducing plasmid DNA uptake and leading to decreased transfection efficiency.

The degree of endotoxin toxicity varies significantly among cell lines. Some cell lines are extremely sensitive to endotoxin and show dysfunction even at endotoxin concentrations below 1 ng/mL. For example, the cancerous intestinal epithelial cells T84 and Caco-2 are non-responsive to endotoxin, whereas SW620 and HT29 cells can secrete cytokines such as IL-8 upon endotoxin stimulation. In addition, long-established cell lines such as HeLa and CHO may have been naturally selected for endotoxin resistance over time.

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