Hauteigene Antibiotika: Wichtige Erkenntnisse über antimikrobielle Peptide für Klinik und Praxis

Broad-Spectrum Antimicrobial Activity and Improved Stability of a D-Amino Acid Enantiomer of DMPC-10A, the Designed Derivative of Dermaseptin Truncates

DMPC-10A (ALWKKLLKK-Cha-NH₂) is a 10-mer peptide derivative from the N-terminal domain of Dermaseptin-PC which has shown broad-spectrum antimicrobial activity as well as a considerable hemolytic effect. In order to reduce hemolytic activity and improve stability to endogenous enzymes, a D-amino acid enantiomer (DMPC-10B) was designed by substituting all L-Lys and L-Leu with their respective D-form amino acid residues, while the Ala¹ and Trp³ remained unchanged. The D-amino acid enantiomer exhibited similar antimicrobial potency to the parent peptide but exerted lower cytotoxicity and hemolytic activity. Meanwhile, DMPC-10B exhibited remarkable resistance to hydrolysis by trypsin and chymotrypsin. In addition to these advantages, DMPC-10B exhibited an outstanding antibacterial effect against Methicillin-resistant Staphylococcus aureus (MRSA) and Klebsiella pneumoniae using the Galleria mellonella larva model and displayed synergistic activities with gentamicin against carbapenem-resistant K. pneumoniae strains. This indicates that DMPC-10B would be a promising alternative for treating antibiotic-resistant pathogens.

Three-dimensional human skin model infected with Staphylococcus aureus as a tool for evaluation of bioactivity and biocompatibility of antiseptics

In the light of pandemic spreads of multi-drug-resistant micro-organisms, alternative antimicrobial strategies to the use of antibiotics are the focus of research attention. As a prerequisite for medical application, the aim of this study was to develop a three-dimensional full skin infection model to evaluate the bioactivity and biocompatibility of antiseptics in application-relevant concentrations. A three-dimensional (3D) full skin model consisting of collagen-embedded fibroblasts as dermis and a fully differentiated epidermis built from keratinocytes was infected with Staphylococcus aureus. Infected skin models were treated for 24 h with the antiseptics polihexanide, octenidine dihydrochloride, chlorhexidine digluconate and povidone-iodine. Infection resulted in detrimental effects, a strong immune response with increased secretion of lactate dehydrogenase and pro-inflammatory cytokines, and increased gene expression of pro-inflammatory cytokines and antimicrobial peptides after 24 h. Application of antiseptics protected the skin models from damage due to S. aureus infection while demonstrating good biocompatibility. The best ratio of bioactivity to biocompatibility was observed for polihexanide. Polihexanide also enhanced the innate immune response by increasing the gene expression levels of antimicrobial peptides such as human β-defensin 2, human β-defensin 3, psoriasin and ribonuclease 7. The developed model provides an excellent tool to investigate the response of human cells to microbial infections in a complex 3D structure. Furthermore, the infection model is appropriate for evaluation of bioactivity and biocompatibility of antiseptics. As such, the model presented in this study is a promising approach to evaluate the mechanisms and effectiveness of new antimicrobial strategies.

Antimicrobial Peptides and Their Therapeutic Potential for Bacterial Skin Infections and Wounds

Alarming data about increasing resistance to conventional antibiotics are reported, while at the same time the development of new antibiotics is stagnating. Skin and soft tissue infections (SSTIs) are mainly caused by the so called ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species) which belong to the most recalcitrant bacteria and are resistant to almost all common antibiotics. S. aureus and P. aeruginosa are the most frequent pathogens isolated from chronic wounds and increasing resistance to topical antibiotics has become a major issue. Therefore, new treatment options are urgently needed. In recent years, research focused on the development of synthetic antimicrobial peptides (AMPs) with lower toxicity and improved activity compared to their endogenous counterparts. AMPs appear to be promising therapeutic options for the treatment of SSTIs and wounds as they show a broad spectrum of antimicrobial activity, low resistance rates and display pivotal immunomodulatory as well as wound healing promoting activities such as induction of cell migration and proliferation and angiogenesis. In this review, we evaluate the potential of AMPs for the treatment of bacterial SSTIs and wounds and provide an overview of the mechanisms of actions of AMPs that contribute to combat skin infections and to improve wound healing. Bacteria growing in biofilms are more resistant to conventional antibiotics than their planktonic counterparts due to limited biofilm penetration and distinct metabolic and physiological functions, and often result in chronification of infections and wounds. Thus, we further discuss the feasibility of AMPs as anti-biofilm agents. Finally, we highlight perspectives for future therapies and which issues remain to bring AMPs successfully to the market.

[Neurodermatitis : Atopy of the skin]

Atopic dermatitis is one of the most common skin diseases and is associated with an impaired quality of life due to tormenting itching and stigmatization. The disease almost always manifests in early childhood and exhibits specific features in this phase, with involvement of the extensor sides of the extremities. During the further course of disease, the typical flexor involvement becomes quite clear and a considerable proportion of patients develop the associated atopic respiratory diseases. Therapeutic and prophylactic measures focus on the prevention of trigger factors, basic skin care, and application of lipid-replenishing creams, as well as patient and parent education. In the case of exacerbation, anti-inflammatory drugs are treatment of choice.

Acute phase proteins as promising biomarkers: Perspectives and limitations for human and veterinary medicine

Acute phase proteins (APPs) are highly conserved plasma proteins that are increasingly secreted by the liver in response to a variety of injuries, independently of their location and cause. APPs favor the systemic regulation of defense, coagulation, proteolysis, and tissue repair. Various APPs have been applied as general diagnostic parameters for a long time. Through proteomic techniques, more and more APPs have been discovered to be differentially altered. Since they are not consistently explainable by a stereotypic hepatic expression of sets of APPs, most of these results have unfortunately been neglected or attributed to the nonspecificity of the acute phase reaction. Moreover, it appears that various extrahepatic tissues are also able to express APPs. These extrahepatic APPs show focally specific roles in tissue homeostasis and repair and are released primarily into interstitial and distal fluids. Since these focal proteins might leak into the circulatory system, mixtures of hepatic and extrahepatic APP species can be expected in blood. Hence, a selective alteration of parts of APPs might be expected. There are several hints on multiple molecular forms and fragments of tissue-derived APPs. These differences offer the chance for multiple selective determinations. Thus, specific proteoforms might indeed serve as tissue-specific disease indicators.