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Novel antimicrobial peptide-modified azithromycin-loaded liposomes against methicillin-resistant Staphylococcus
Xiaowei Liu1, Zhan Li1, Xiaodong Wang2
1State Key Laboratory of Biotherapy/Collaborative Innovation Center for Biotherapy.
Abstract:
Infections caused by multidrug-resistant bacteria, such as methicillin-resistant Staphylococcus aureus (MRSA), have become a public threat; therefore, development of new antimicrobial drugs or strategies is urgently required. In this study, a new antibacterial peptide DP7-C (Chol-suc-VQWRIRVAVIRK-NH2) and DP7-C-modified azithromycin (AZT)-loaded liposomes (LPs) are developed for the treatment of MRSA infection, and it was found that DP7-C inserted into the LP lipid bilayer not only functioned as a carrier to encapsulate the antibiotic AZT but also synergized the antibacterial effect of the encapsulated AZT. In vitro assays showed that DP7-C-modified LPs possessed sustained drug release profile and immune regulatory effect and did not show obvious cytotoxicity in mammal cells, but they did not possess direct antibacterial activity in vitro. In vivo studies revealed that DP7-C-modified LPs did not exhibit obvious side effects or toxicity in mice but were able to significantly reduce the bacterial counts in an MRSA-infectious mouse model and possessed high antibacterial activity. In particular, DP7-C-modified AZT-loaded LPs showed more positive therapeutic effects than either DP7-C-modified blank LPs or nonmodified AZT-loaded LPs treatment alone. Molecular mechanism studies demonstrated that DP7-C formulations effectively upregulated the production of anti-inflammatory cytokines and chemokines without inducing harmful immune response, suggesting that DP7-C was synergistic with AZT against the bacterial infection by activating the innate immune response. Most importantly, although DP7-C activated the innate immune response, it did not possess direct antibacterial activity in vitro, indicating that DP7-C did not possess the potential to induce bacteria resistance. The findings indicate that DP7-C-modified AZT-loaded LPs developed in this study have a great potential required for the clinical treatment of MRSA infections.
Insights
A novel peptide, DP7-C, enhances liposomal azithromycin for treating methicillin-resistant Staphylococcus aureus (MRSA) infections. This combination therapy shows potent antibacterial activity and activates innate immunity without inducing bacterial resistance.
Area of Science:
- Antimicrobial drug development
- Nanomedicine
- Immunology
Background:
- Multidrug-resistant bacterial infections, particularly methicillin-resistant Staphylococcus aureus (MRSA), pose a significant public health threat.
- Urgent need for novel antimicrobial strategies to combat resistant pathogens.
Purpose of the Study:
- To develop and evaluate DP7-C-modified azithromycin (AZT)-loaded liposomes (LPs) for MRSA infection treatment.
- To investigate the synergistic antibacterial effects and underlying mechanisms of the novel formulation.
Main Methods:
- Synthesis and characterization of DP7-C-modified AZT-loaded LPs.
- In vitro assays for drug release, cytotoxicity, and antibacterial activity.
- In vivo studies in an MRSA-infectious mouse model to assess efficacy and toxicity.
- Molecular mechanism studies to analyze immune response and cytokine production.
Main Results:
- DP7-C-modified LPs demonstrated sustained drug release and immune regulatory effects in vitro without significant mammalian cell cytotoxicity.
- In vivo studies showed reduced bacterial counts in MRSA-infected mice with no obvious side effects or toxicity.
- The DP7-C-modified AZT-loaded LPs exhibited superior therapeutic effects compared to non-modified LPs or blank LPs.
- DP7-C activated innate immune responses by upregulating anti-inflammatory cytokines and chemokines, contributing to synergistic effects with AZT.
Conclusions:
- DP7-C-modified AZT-loaded LPs represent a promising strategy for treating MRSA infections.
- The formulation synergizes with AZT by activating innate immunity and shows potential for clinical application.
- DP7-C's lack of direct antibacterial activity suggests a low risk of inducing bacterial resistance.
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