Bacterial endotoxin-lipopolysaccharide; structure, function and its role in immunity in vertebrates and invertebrates

Biotic and abiotic factors shape investment in costly defenses. The immune systems of vertebrates and invertebrates differ in their fitness cost. However, the hygienic behavior of both can result in increased survival rate and fitness cost. The immune response of vertebrates has developed more sophisticated and complicated mechanisms including an immunological memory with the generation of large antigen-recognition receptors and innate immune systems. The invertebrate immune system must rely on non-self-recognition molecules to ensure efficient defense responses against infectious pathogens that continuously threaten their survival. Lipopolysaccharide (LPS) from bacterial endotoxin, has been regarded as having potential molecules involved in immune recognition and immune defense. This review focused on an overview of bacterial endotoxin, LPS, and their structure, function, and elucidation of immune responses in both vertebrates and invertebrates are discussed. In addition, invertebrate defense against LPS is reviewed in detail. The precise mechanisms underlying self and non-self-recognition represent the basis to prevent and control infections from endotoxins as well as to stimulate animal resistance. This is particularly relevant for immune defense against LPS in invertebrates and vertebrates which are frequently constrained by recurrent diseases.