Triintsin, a human pathogenic fungus-derived defensin with broad-spectrum antimicrobial activity

Antimicrobial Mechanisms and Clinical Application Prospects of Antimicrobial Peptides

Antimicrobial peptides are a type of small-molecule peptide that widely exist in nature and are components of the innate immunity of almost all living things. They play an important role in resisting foreign invading microorganisms. Antimicrobial peptides have a wide range of antibacterial activities against bacteria, fungi, viruses and other microorganisms. They are active against traditional antibiotic-resistant strains and do not easily induce the development of drug resistance. Therefore, they have become a hot spot of medical research and are expected to become a new substitute for fighting microbial infection and represent a new method for treating drug-resistant bacteria. This review briefly introduces the source and structural characteristics of antimicrobial peptides and describes those that have been used against common clinical microorganisms (bacteria, fungi, viruses, and especially coronaviruses), focusing on their antimicrobial mechanism of action and clinical application prospects.

Strategies for Antimicrobial Peptides Immobilization on Surfaces to Prevent Biofilm Growth on Biomedical Devices

Nosocomial and medical device-induced biofilm infections affect millions of lives and urgently require innovative preventive approaches. These pathologies have led to the development of numerous antimicrobial strategies, an emergent topic involving both natural and synthetic routes, among which some are currently under testing for clinical approval and use. Antimicrobial peptides (AMPs) are ideal candidates for this fight. Therefore, the strategies involving surface functionalization with AMPs to prevent bacterial attachment/biofilms formation have experienced a tremendous development over the last decade. In this review, we describe the different mechanisms of action by which AMPs prevent bacterial adhesion and/or biofilm formation to better address their potential as anti-infective agents. We additionally analyze AMP immobilization techniques on a variety of materials, with a focus on biomedical applications. Furthermore, we summarize the advances made to date regarding the immobilization strategies of AMPs on various surfaces and their ability to prevent the adhesion of various microorganisms. Progress toward the clinical approval of AMPs in antibiotherapy is also reviewed.

Inhibitory Activity of a Scorpion Defensin BmKDfsin3 against Hepatitis C Virus

Hepatitis C virus (HCV) infection is a major worldwide health problem which can cause chronic hepatitis, liver fibrosis and hepatocellular carcinoma (HCC). There is still no vaccine to prevent HCV infection. Currently, the clinical treatment of HCV infection mainly relies on the use of direct-acting antivirals (DAAs) which are expensive and have side effects. Here, BmKDfsin3, a scorpion defensin from the venom of Mesobuthus martensii Karsch, is found to dose-dependently inhibit HCV infection at noncytotoxic concentrations and affect viral attachment and post-entry in HCV life cycle. Further experimental results show that BmKDfsin3 not only suppresses p38 mitogen-activated protein kinase (MAPK) activation of HCV-infected Huh7.5.1 cells, but also inhibits p38 activation of Huh7.5.1 cells stimulated by tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) or lipopolysaccharide (LPS). BmKDfsin3 is also revealed to enter into cells. Using an upstream MyD88 dimerization inhibitor ST2345 or kinase IRAK-1/4 inhibitor I, the inhibition of p38 activation represses HCV replication in vitro. Taken together, a scorpion defensin BmKDfsin3 inhibits HCV replication, related to regulated p38 MAPK activation.