Design of High-Selectivity Co-Assembled Peptide Nanofibers against Bacterial Infection in Piglets.

Antibiotic resistance is an escalating global health concern that could result in tens of millions of deaths annually from drug-resistant bacterial infections in the future, especially in animal husbandry. Peptide antibacterial nanomaterials offer a competitive alternative to antibiotics because of their distinct mechanism of physically penetrating pathogenic biological membranes. This study developed amphiphilic co-assembled peptide nanofibers with high biological selectivity (PCBP-NCAP NFs) to overcome the high cytotoxicity of peptide PCBP and the low antibacterial activity of peptide NCAP. PCBP-NCAP NFs exhibit broad-spectrum antibacterial activity and excellent biocompatibility, with negligible in vivo and in vitro toxicity. Additionally, PCBP-NCAP NFs possess direct antibacterial efficacy and potential immunomodulatory capabilities using a piglet systemic infection model. Its unique mechanism of membrane penetration and the ability to bind to anionic components on the surface of pathogenic bacteria make them less susceptible to drug resistance. In conclusion, these findings have significant implications for the advancement of supramolecular peptide nanomedicines for clinical application and animal husbandry.

Hydrophobic modification improves the delivery of cell-penetrating peptides to eliminate intracellular pathogens in animals.

Infections induced by intracellular pathogens are difficult to eradicate due to poor penetration of antimicrobials into cell membranes. It is of great importance to develop a new generation of antibacterial agents with dual functions of efficient cell penetration and bacterial inhibition. In this study, the association between hydrophobicity and cell-penetrating peptide delivery efficiency was investigated by fragment interception and hydrophobicity modification of natural porcine antimicrobial peptide PR-39 and the combination of cationic cell-penetrating peptide (R6) with antimicrobial peptide fragments modified with hydrophobic residues. The chimeric peptides P3I7 and P3L7, obtained through biofunctional screening, exhibited potent broad-spectrum antibacterial activity and low cytotoxicity. Moreover, P3I7 and P3L7 can effectively penetrate cells to eliminate intracellular pathogens mainly through endocytosis. The membrane destruction mechanism makes the peptides fast sterilizers and less prone to developing drug resistance. Finally, their good biocompatibility and antibacterial infection effects were verified in mice and piglets. To conclude, the chimeric peptides P3I7 and P3L7 show great potential as affordable and effective antimicrobial agents and may serve as ideal candidates for the treatment of intracellular bacterial infections. STATEMENT OF SIGNIFICANCE: The low permeability of antibacterial drugs makes infections induced by intracellular bacteria extremely difficult to treat. To address this issue, we designed chimeric peptides with dual cell-penetrating and antibacterial functions. The active peptides P3I7 and P3L7, acquired through functional screening have strong broad-spectrum antibacterial activity and powerful bactericidal effects against intracellular Staphylococcus aureus. The membrane permeation mechanism of P3I7 and P3L7 against bacteria endows fast bactericidal activity with low drug resistance. The biosafety and antibacterial activity of P3I7 and P3L7 were also validated by in vivo trials. This study provides an ideal drug candidate against intracellular bacterial infections.

Wickerhamomyces anomalus relieves weaning diarrhea via improving gut microbiota and redox homeostasis using a piglet model.

Weaning stress commonly damages the intestinal barrier of mammals, resulting in gut microbiota dysbiosis, intestinal illness, and even severe diarrhea. Probiotics are used as a nutritional strategy to promote the health of humans and animals and the gut microbiota balance. Here Wickerhamomyces anomalus was applied as a probiotic supplement to a weaned piglet model to investigate its impacts on growth performance, antioxidant capacity, inflammation response, and intestinal health. Supplemental 1 g kg-1 108 cfu g-1W. anomalus 13611 significantly decreased the feed conversion ratio (FCR), alleviated diarrhea, improved the apparent total tract digestibility of neutral detergent fiber (NDF) and gross energy (GE), increased the concentration of total antioxidant capacity (T-AOC) and catalase (CAT) in serum, and decreased the concentration of malondialdehyde (MDA) and pro-inflammatory cytokines such as interleukin-1ß (IL-1ß) in serum. Importantly, supplementation of W. anomalus 13611 also improved the gut microbiota, decreasing the relative abundance of Oxalobacteraceae, enriching the relative abundances of Lactobacillaceae and Lactobacillus, and increasing the relative abundances of two species of Lactobacillus (helveticus and delbrueckii). In conclusion, W. anomalus 13611 could effectively promote growth performance and alleviate diarrhea in a model of weaned piglets, which may be related to improved antioxidant activity, anti-inflammatory response, and alteration in the structure of the gut microbiota.