Overview of Host Defense Peptides and Their Applications for Plastic and Reconstructive Surgeons

Abstract

Background: Host defense peptides are a family of endogenous short peptides that are found in all living beings and play a critical role in innate immunity against infection. Methods: A nonsystematic review of host defense peptides was conducted with specific interest in properties and applications relevant to plastic and reconstructive surgery. Results: In addition to their direct antimicrobial actions against pathogens, including multidrug-resistant bacteria, they also demonstrate important functions in immunomodulation, tumor cell lysis, and tissue regeneration. These properties have made them a topic of clinical interest for plastic surgeons because of their potential applications as novel antibiotics, wound healing medications, and cancer therapies. The rising clinical interest has led to a robust body of literature describing host defense peptides in great depth and breadth. Numerous mechanisms have been observed to explain their diverse functions, which rely on specific structural characteristics. However, these peptides remain mostly experimental, with limited translation to clinical practice because of numerous failures to achieve acceptable results in human trials. Conclusions: Despite the broad ranging potential of these peptides for use in the field of plastic and reconstructive surgery, they are rarely discussed in the literature or at scientific meetings. In this review, the authors provide a summary of the background, structure, function, bacterial resistance, and clinical applications of host defense peptides with the goal of stimulating host defense peptide–based innovation within the field of plastic and reconstructive surgery.

Cathelicidin LL-37 Expression in Human Breast Implant Capsules

“…Although initially investigated for its antimicrobial role, it was discovered to have pleiotropic activities, such as immunomodulation, angiogenesis stimulation, and tissue healing promotion. 11 In the present study, we found that cathelicidin LL-37 may be expressed by both macrophages and myofibroblasts, two main players in the process of capsular formation and contracture. Such host defense peptide was found in all of the clinically infected specimens but not in every noninfected capsule.…”

“…It was proved to have broad-spectrum antimicrobial activity, to promote tissue healing, and to exert immunomodulatory and proangiogenic effects. 11 In other tissues, it showed several interactions with receptors, cells, and processes also involved in capsular contracture. Specifically, it stimulated the activation of neutrophils, macrophages, and myofibroblasts.…”

Resistin, a Novel Host Defense Peptide of Innate Immunity

“…The "head" region of human resistin also contains several residues exposed to the molecular surface, namely Leu42, Pro46, Phe49, and Trp80, which have been proved to play a role in imparting surface hydrophobicity to the molecule (Figure 1B) (34). Typically, the cationicity and hydrophobicity of the peptides are considered to be two critical elements for their antibacterial action as they are instrumental for binding and insertion into bacterial membranes (2,37). It is, therefore, speculated that the C-terminal "head" domain of resistin may be the molecular basis of its antibacterial activity.…”

“…Host defense peptides are endogenous short-peptide compounds that are recognized as a critical component of the innate immune system and are found in epithelial barriers and circulating leukocytes (1,2). These peptides vary from 10 to 150 amino acids with a net charge between -3 and +20, which have a broad-spectrum antimicrobial activity and diverse immunomodulatory activities (3)(4)(5)(6).…”