detection of lipopolysaccharide

Definition

Target type: biologicalprocess

The series of events in which a lipopolysaccharide stimulus is received by a cell and converted into a molecular signal. Lipopolysaccharide is a major component of the cell wall of gram-negative bacteria. [GOC:add, PMID:15998797]

Lipopolysaccharide (LPS), a major component of the outer membrane of Gram-negative bacteria, is recognized by the innate immune system through a complex cascade of events. This detection process involves specialized immune cells and signaling pathways that ultimately lead to the activation of inflammatory responses.

The initial step in LPS recognition involves the interaction of LPS with specific pattern recognition receptors (PRRs). The most critical PRR for LPS recognition is Toll-like receptor 4 (TLR4), a transmembrane protein expressed on the surface of various immune cells, including macrophages, dendritic cells, and neutrophils. TLR4 forms a complex with accessory proteins, such as MD-2 and CD14, which facilitate its binding to LPS.

Upon binding to TLR4, LPS triggers a series of intracellular signaling events. This process begins with the activation of adaptor proteins, such as MyD88 and TRIF, which are recruited to the TLR4 complex. These adaptor proteins activate downstream signaling pathways, including the NF-κB pathway and the MAPK pathway.

The NF-κB pathway is a key regulator of inflammatory gene expression. Activation of NF-κB leads to the production of pro-inflammatory cytokines, such as TNF-α, IL-1β, and IL-6. These cytokines mediate a wide range of inflammatory responses, including fever, pain, and tissue damage.

The MAPK pathway also plays a crucial role in LPS-induced inflammation. Activation of MAPK signaling cascades leads to the production of chemokines, which attract immune cells to the site of infection.

In addition to the activation of inflammatory responses, LPS detection also triggers the production of type I interferons (IFNs). IFNs are antiviral cytokines that help to control viral infections.

The detection of LPS by the immune system is essential for the host's defense against Gram-negative bacterial infections. However, excessive or uncontrolled LPS signaling can lead to septic shock, a life-threatening condition characterized by systemic inflammation and organ dysfunction.

In summary, the detection of LPS involves a complex interplay between PRRs, adaptor proteins, signaling pathways, and immune cells. This process is essential for the host's defense against Gram-negative bacteria but can also contribute to the development of septic shock.'
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Proteins (4)

Compounds (13)