Sample Essay on Lipopolysaccharide Binding Protein
Lipopolysaccharide binding protein [LBP] is a protein that in humans is encrypted by the LBP gene. The LBP is a soluble acute-phase protein that binds to bacterial lipopolysaccharide [LPS] to mainly cause immune responses by easily presenting the LPS to the important cell surface pattern recognition receptors; CD14 and TLR4. The LPS- binding protein [LBP] has a concentration dependent-dual role when it comes to pathogenesis of gram-negative sepsis. The low concentration of LBP also enhances the LPS- stimulated activation of the mononuclear cells [MNC]. On the other hand, the acute phase rise in LBP concentration also inhibits LPS- prompted cellular stimulation.
The Lipopolysaccharide binding protein also arbitrates the lipopolysaccharide stimulated cytokine release from the mononuclear cells even when under serum free conditions. LBP also binds and enters into the lipid membranes, making it easy to intervene with the CD14 intercalation of the LPS into the cell membranes. In case of reduced production of tumor necrosis factor by the mononuclear cells, it is wise to incorporate LBP as a transmembrane protein in the cytoplasmic membrane of MNC. In addition, it is wise to consider the interaction of lipopolysaccharide with the membrane-linked LBP, as it will aid in LBP- stimulated activation of the MNC.
The human lipopolysaccharide binding protein is made up of a serum glycoprotein originating from the family of lipid-binding proteins. These lipid binding proteins include bactericidal/ permeability- increasing protein [BPI]. Surprisingly, the Lipopolysaccharide binding protein play dual roles. First, the low concentrations of LBP improve the LPS –stimulated activation of mononuclear cells. Secondly, the acute-phase rise in LBP concentrations inhibits LPS –induced cellular stimulation. Lipopolysaccharide binding protein binds a number of LPS [endotoxin] chemotypes from rough and smooth strains of gram-negative bacteria and lipid A. The LPS molecules and components of the out membrane of the gram-negative bacteria act as great links in pathogenesis of sepsis and septic shock.
Lipopolysaccharide also aids in secretion of inflammatory cytokines by activating monocytes and macrophages. This is possible through secretion via the intracellular signal amplification pathway. These mediators act on the additional target cells to produce cardiovascular shock, septic shock and multisystem organ failure, one of the activities that have been highlighted as the major cause of death in intensive care units. Receptors aid in mediating cellular responses in living organisms. For the endotoxin recognition, a binding protein receptor system has been postulated to involve LBP, the membrane bound and soluble CD14 molecules.
LBP has always been compared to BPI as both proteins bind LPS. A chain of comparison also revealed that human LBP and BPI share 44% of amino acid identity. BPI has also been on the cell surface of human peripheral blood monocytes. Nevertheless, in contrast to BPI, LBP does not affect the practicality of the gram-negative bacteria concentration where BPI is very effective. In addition, the effects of LBP and BPI on LPS- stimulated cytokine release form the mononuclear phagocytic cells are remedial. Other areas that the lipopolysaccharide binding protein is depended on include an acute-phase protein synthesizing process primarily in the liver of the mammalian host. Phagocytosis was also dependent on LBP and CD14 and it has great impact on the performance of the LBP regardless of the cell conditions. Experiments such as immunologic, biochemical and molecular biologic approaches have helped demonstrate the importance of LBP/CD14- dependent pathway.
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