A Nanocomposite with Extracellular Vesicles from Lactobacillus paracasei as a Bioinspired Nanoantibiotic Targeting Staphylococcus aureus

Lactobacilli-derived extracellular vesicles as synergistic biomolecules for colistin efficacy against Acinetobacter baumannii

Acinetobacter baumannii (A. baumannii), a gram-negative bacterium resistant to antibiotics, presents substantial medical challenges, causing nosocomial infections with high fatality rates. Colistin (COL) is frequently employed as a last-line defense against these pathogens. Nevertheless, its therapeutic efficacy has been significantly reduced due to the emergence of COL-resistant strains. With the slow development of novel antibiotics, researchers have explored materials to boost the effectiveness of COL against such pathogens. Postbiotics, comprising bioactive compounds derived from probiotic microorganisms, have shown potential antibacterial properties and may work synergistically with certain antibiotics. This study aimed to confirm the role of extracellular vesicles (EVs) as a collection of bioactive molecules that could potentially synergize with COL. EVs from various Lactobacilli strains (LEVs) were evaluated for their effect on COL susceptibility. The findings indicated that, compared to COL treatment alone, LEVs enhanced 4- to 8-fold bactericidal efficacy of COL against A. baumannii strains in the level of minimum inhibitory concentrations (MIC). Additional mechanistic investigations into the synergistic effects of LEVs on established COL mechanisms, including lipopolysaccharide binding, reactive oxygen species (ROS) generation, and biofilm formation, showed that LEVs act as either ROS enhancers or biofilm inhibitors, depending on the bacterial strains. Finally, we demonstrated that repeated use of LEVs did not induce COL resistance in A. baumannii. These results provide the first evidence that LEVs can serve as effective postbiotics, enhancing the susceptibility of A. baumannii strains to COL.

Nanoparticle-Based Drug Delivery for Vascular Applications

Nanoparticle (NP)-based drug delivery systems have received widespread attention due to the excellent physicochemical properties of nanomaterials. Different types of NPs such as lipid NPs, poly(lactic-co-glycolic) acid (PLGA) NPs, inorganic NPs (e.g., iron oxide and Au), carbon NPs (graphene and carbon nanodots), 2D nanomaterials, and biomimetic NPs have found favor as drug delivery vehicles. In this review, we discuss the different types of customized NPs for intravascular drug delivery, nanoparticle behaviors (margination, adhesion, and endothelium uptake) in blood vessels, and nanomaterial compatibility for successful drug delivery. Additionally, cell surface protein targets play an important role in targeted drug delivery, and various vascular drug delivery studies using nanoparticles conjugated to these proteins are reviewed. Finally, limitations, challenges, and potential solutions for translational research regarding NP-based vascular drug delivery are discussed.

Host immunomodulation strategies to combat pandemic-associated antimicrobial-resistant secondary bacterial infections

The incidence of secondary bacterial infections has increased in recent decades owing to various viral pandemics. These infections further increase the morbidity and mortality rates associated with viral infections and remain a significant challenge in clinical practice. Intensive antibiotic therapy has mitigated the threat of such infections; however, overuse and misuse of antibiotics have resulted in poor outcomes, such as inducing the emergence of bacterial populations with antimicrobial resistance (AMR) and reducing the therapeutic options for this crisis. Several antibiotic substitutes have been suggested and employed; however, they have certain limitations and novel alternatives are urgently required. This review highlights host immunomodulation as a promising strategy against secondary bacterial infections to overcome AMR. The definition and risk factors of secondary bacterial infections, features and limitations of currently available therapeutic strategies, host immune responses, and future perspectives for treating such infections are discussed.

Role of probiotic extracellular vesicles in inter-kingdom communication and current technical limitations in advancing their therapeutic utility

Diverse functions of probiotic extracellular vesicles (EVs) have been extensively studied over the past decade, proposing their role in inter-kingdom communication. Studies have explored their therapeutic role in pathophysiological processes ranging from cancer, immunoregulation, and ulcerative colitis to stress-induced depression. These studies have highlighted the significant and novel potential of probiotic EVs for therapeutic applications, offering immense promise in addressing several unmet clinical needs. Additionally, probiotic EVs are being explored as vehicles for targeted delivery approaches. However, the realization of clinical utility of probiotic EVs is hindered by several knowledge gaps, pitfalls, limitations, and challenges, which impede their wider acceptance by the scientific community. Among these, limited knowledge of EV biogenesis, markers and regulators in bacteria, variations in cargo due to culture conditions or EV isolation method, and lack of proper understanding of gut uptake and demonstration of in vivo effect are some important issues. This review aims to summarize the diverse roles of probiotic EVs in health and disease conditions. More importantly, it discusses the significant knowledge gaps and limitations that stand in the way of the therapeutic utility of probiotic EVs. Furthermore, the importance of addressing these gaps and limitations with technical advances such as rigorous omics has been discussed.

Friends against the Foe: Synergistic Photothermal and Photodynamic Therapy against Bacterial Infections

Multidrug-resistant (MDR) bacteria are rapidly emerging, coupled with the failure of current antibiotic therapy; thus, new alternatives for effectively treating infections caused by MDR bacteria are required. Hyperthermia-mediated photothermal therapy (PTT) and reactive oxygen species (ROS)-mediated photodynamic therapy (PDT) have attracted extensive attention as antibacterial therapies owing to advantages such as low invasiveness, low toxicity, and low likelihood of causing bacterial resistance. However, both strategies have notable drawbacks, including the high temperature requirements of PTT and the weak ability of PDT-derived ROS to penetrate target cells. To overcome these limitations, a combination of PTT and PDT has been used against MDR bacteria. In this review, we discuss the unique benefits and limitations of PTT and PDT against MDR bacteria. The mechanisms underlying the synergistic effects of the PTT-PDT combination are also discussed. Furthermore, we introduced advancements in antibacterial methods using nano-based PTT and PDT agents to treat infections caused by MDR bacteria. Finally, we highlight the existing challenges and future perspectives of synergistic PTT-PDT combination therapy against infections caused by MDR bacteria. We believe that this review will encourage synergistic PTT- and PDT-based antibacterial research and can be referenced for future clinical applications.