Antimicrobial peptides from marine invertebrates as a new frontier for microbial infection control

Abstract

Antimicrobial peptides are widely expressed in organisms and have been linked to innate and acquired immunities in vertebrates. These compounds are constitutively expressed and rapidly induced at different cellular levels to interact directly with infectious agents and/or modulate immunoreactions involved in defense against pathogenic microorganisms. In invertebrates, antimicrobial peptides represent the major humoral defense system against infection, showing a diverse spectrum of action mechanisms, most of them related to plasma membrane disturbance and lethal alteration of microbial integrity. Marine invertebrates are widespread, extremely diverse, and constantly under an enormous microbial challenge from the ocean environment, itself altered by anthropic influences derived from industrialization and transportation. Consequently, this study reexamines the peptides isolated over the past 2 decades from different origins, bringing phyla not previously reviewed up to date. Moreover, a promising novel use of antimicrobial peptides as effective drugs in human and veterinary medicine could be based on their unusual properties and synergic counterparts as immune response humoral effectors, in addition to their direct microbicidal activity. This has been seen in many other marine proteins that are sufficiently immunogenic to humans, not necessarily in terms of antibody generation but as inflammation promoters and recruitment agents or immune enhancers.

A defensin from clam Venerupis philippinarum: Molecular characterization, localization, antibacterial activity, and mechanism of action

“…The direct antibiotic activity of AMPs is thought to be based on their cationic and amphiphilic nature, which enables these peptides to interact with negatively charged bacterial surfaces and membranes, subsequently causing membrane disruption or altering metabolic processes (Brogden, 2005;Hale and Hancock, 2007). AMPs represent potential substitutes for antibiotics due to their broad specificity against bacteria or fungi, and their anti-viral, anti-tumoral, anti-inflammatory, wound-healing, and immunomodulatory activities (Diamond et al, 2009;Otero-González et al, 2010). Despite being evolutionary ancient, AMPs exhibit great diversity in terms of structural features, biological properties and functions, and also in their tissue distribution and expression profiles (Bachere et al, 2004;Bulet et al, 2004).…”

Ci8 short, a novel LPS-induced peptide from the ascidian Ciona intestinalis, modulates responses of the human immune system

“…Many discoveries have been made in the field, but the mechanisms by which the innate immune system can control adaptive immunity remain to be fully clarified. Invertebrates produce a large number of bioactive molecules which have been proven to fulfill important immunological roles such as antibacterial or anticancer activities (Otero-González et al, 2010;Cheung et al, 2015;Suarez-Jimenez et al, 2012). A recent idea is to use invertebrates as a source of molecules with potential immunoregulatory activities to improve strategies for studying human immune system responses (Davis, 2008;Germain and Schwartzberg, 2011).…”

Molecular diversity and evolution of defensins in the manila clam Ruditapes philippinarum

“…In marine invertebrates, AMPs represent the major humoral defense system against infection. The modes of action by which AMPs kill bacteria are diverse, and most of them related to plasma membrane disturbance and lethal alteration of microbial integrity [5]. In marine mollusks, several kinds of AMPs have been characterized and studied, including defensins, mytilins, myticins, mytimycin, big defensins and mytimacins [6e13].…”