Recent advances in the field of antimicrobial peptides in inflammatory diseases

Abstract

Antimicrobial peptides are cationic molecules, which participate in multiple aspects of the immune response including the control of inflammatory diseases, characteristic that make these molecules attractive as therapeutic tools. These peptides are produced in bacteria, insects, plants and vertebrates, and are classified together due to their capacity to directly inhibit the growth of microorganisms, and to regulate the immune response by inducing the secretion of chemokines and cytokines. Various families of antimicrobial peptides have been identified including the cathelicidins and defensins, the most investigated human antimicrobial peptides. This review will cover the main biological functions of antimicrobial and cell-penetrating peptides in inflammation, and describe the importance and utility of antimicrobial peptides as therapeutics for inflammatory diseases.

Cathelicidin – Its Structure, Function and the Role in Autoimmune Diseases

“…They act within the cell membranes [32,50]. These peptides were first described in the early 1980s, in wounded frogs and toads [32]. The excretion of a substance subsequently named marginin was observed directly following an injury.…”

“…They are positively charged, hydrophobic and/or amphipathic. They act within the cell membranes [32,50]. These peptides were first described in the early 1980s, in wounded frogs and toads [32].…”

“…Therefore, a host body needs to be equipped with the defence mechanisms that exert an effect prior to a targeted immune response. The latter one may be triggered too late to compete with the kinetics of the pathogens' proliferation [32,50]. The AMPs mechanism of action consists in the peptide binding with the bacterial phospholipid membrane until a threshold concentration is reached, followed by the leakage, depolarisation and disintegration of the cell membrane, and, consequently, cell death [1,14,46].…”

“…Meanwhile, these peptides participate in maturation and activation of autophagy [22], as well as in the process of wound healing [51]. Their insufficiency may lead to diseases, such as atopic dermatitis [2,10], Kostmann disease [32], cystic fibrosis [50] or autoimmune diseases, including systemic lupus erythematosus (SLE) [26]. Understanding the AMPs' mechanism of action may facilitate the development of antimicrobial drugs imitating human immune system.…”

“…They constitute a protection shield in the epithelium, where their expression may be induced during an infection or inflammation. AMPs' primary functions include: elimination of infectious pathogens [31,44,48], stimulation of cytokines' secretion [16,40,48] and of angiogenesis [7], inhibition of apoptosis [8,23,30], and activation of chemotactic [34,50,55], dendritic [12,15,32] and mast [7] cells. Meanwhile, these peptides participate in maturation and activation of autophagy [22], as well as in the process of wound healing [51].…”