Cathelicidins: Cationic Host Defense and Antimicrobial Peptides

Cathelicidins are members of a family of protective, anti-infective peptides, also known as host defense peptides, and are defined by the high degree of conservation of their pre-pro precursor sequences and exceptional diversity of sequence and structure in the mature peptide. All cathelicidins are small cationic, amphiphilic peptides composed of 12-97 amino acids. Cathelicidins promote chemotaxis of effector cells, induce the transcription and secretion of chemokines, and induce mast cell degranulation, resulting in enhanced vascular permeabilization and leukocyte infiltration. Thus, cathelicidins might be considered pro-inflammatory mediators. However, they also protect the host against detrimental, potentially lethal, effects resulting from an excessive inflammatory response to microbial invasion. The biological effects exerted by cathelicidins at a given time and place are likely determined by the physiological setting, including the concentration of the peptide, cellular environment, and soluble components of the extracellular milieu.