Investigations into the membrane activity of arenicin antimicrobial peptide AA139

High-yield and cost-effective biosynthesis process for producing antimicrobial peptide AA139

AA139, a variant of natural antimicrobial peptide (AMP) arenicin-3, displayed potent activity against multidrug-resistant (MDR) and extensively drug-resistant (XDR) Gram-negative bacteria. Nevertheless, there were currently few reports on the bioprocess of AA139, and the yields were less than 5 mg/L. Additionally, it was difficult and expensive to prepare AA139 through chemical synthesis due to its complex structure. These factors have impeded the further research and following clinical application of AA139. Here, we reported a bioprocess for the preparation of AA139, which was expressed in Escherichia coli (E. coli) BL21 (DE3) intracellularly in a soluble form via SUMO (small ubiquitin-related modifier) fusion technology. Then, recombinant AA139 (rAA139, refer to AA139 obtained by recombinant expression in this study) was obtained through the simplified downstream process, which was rationally designed in accordance with the physicochemical characteristics. Subsequently, the expression level of the interest protein was increased by 54% after optimization of high cell density fermentation (HCDF). Finally, we obtained a yield of 56 mg of rAA139 from 1 L culture with a purity of 98%, which represented the highest reported yield of AA139 to date. Furthermore, various characterizations were conducted to confirm the molecular mass, disulfide bonds, and antimicrobial activity of rAA139.

Antimicrobial Peptides (AMPs) and the Microbiome in Preterm Infants: Consequences and Opportunities for Future Therapeutics

Antimicrobial peptides (AMPs) are crucial components of the innate immune system in various organisms, including humans. Beyond their direct antimicrobial effects, AMPs play essential roles in various physiological processes. They induce angiogenesis, promote wound healing, modulate immune responses, and serve as chemoattractants for immune cells. AMPs regulate the microbiome and combat microbial infections on the skin, lungs, and gastrointestinal tract. Produced in response to microbial signals, AMPs help maintain a balanced microbial community and provide a first line of defense against infection. In preterm infants, alterations in microbiome composition have been linked to various health outcomes, including sepsis, necrotizing enterocolitis, atopic dermatitis, and respiratory infections. Dysbiosis, or an imbalance in the microbiome, can alter AMP profiles and potentially lead to inflammation-mediated diseases such as chronic lung disease and obesity. In the following review, we summarize what is known about the vital role of AMPs as multifunctional peptides in protecting newborn infants against infections and modulating the microbiome and immune response. Understanding their roles in preterm infants and high-risk populations offers the potential for innovative approaches to disease prevention and treatment.

Promising antibacterial efficacy of arenicin peptides against the emerging opportunistic pathogen Mycobacterium abscessus

BACKGROUND

Mycobacterium abscessus, a fast-growing non-tuberculous mycobacterium, is an emerging opportunistic pathogen responsible for chronic bronchopulmonary infections in people with respiratory diseases such as cystic fibrosis (CF). Due to its intrinsic polyresistance to a wide range of antibiotics, most treatments for M. abscessus pulmonary infections are poorly effective. In this context, antimicrobial peptides (AMPs) active against bacterial strains and less prompt to cause resistance, represent a good alternative to conventional antibiotics. Herein, we evaluated the effect of three arenicin isoforms, possessing two or four Cysteines involved in one (Ar-1, Ar-2) or two disulfide bonds (Ar-3), on the in vitro growth of M. abscessus.

METHODS

The respective disulfide-free AMPs, were built by replacing the Cysteines with alpha-amino-n-butyric acid (Abu) residue. We evaluated the efficiency of the eight arenicin derivatives through their antimicrobial activity against M. abscessus strains, their cytotoxicity towards human cell lines, and their hemolytic activity on human erythrocytes. The mechanism of action of the Ar-1 peptide was further investigated through membrane permeabilization assay, electron microscopy, lipid insertion assay via surface pressure measurement, and the induction of resistance assay.

RESULTS

Our results demonstrated that Ar-1 was the safest peptide with no toxicity towards human cells and no hemolytic activity, and the most active against M. abscessus growth. Ar-1 acts by insertion into mycobacterial lipids, resulting in a rapid membranolytic effect that kills M. abscessus without induction of resistance.

CONCLUSION

Overall, the present study emphasized Ar-1 as a potential new alternative to conventional antibiotics in the treatment of CF-associated bacterial infection related to M. abscessus.

Antibacterial Properties of Gold Nanoparticles in the Modification of Medical Implants: A Systematic Review

The widespread occurrence of bacterial infections and their increased resistance to antibiotics has led to the development of antimicrobial coatings for multiple medical implants. Owing to their desirable properties, gold nanoparticles (AuNPs) have been developed as antibacterial agents. This systematic investigation sought to analyze the antibacterial effects of implant material surfaces modified with AuNPs. The data from 27 relevant studies were summed up. The included articles were collected from September 2011 to September 2021. According to the retrieved literature, we found that medical implants modified by AuNPs have good antibacterial effects against gram-positive and gram-negative bacteria, and the antibacterial effects would be improved by near-infrared (NIR) radiation.