Lactobacillus crispatus-loaded electrospun fibers yield viable and metabolically active bacteria that kill Gardnerella in vitro

Electrospun nanofibers: Focus on local therapeutic delivery targeting infectious disease

Whether it be due to genetic variances, lack of patient adherence, or sub-optimal drug metabolism, the risk of antibiotic resistance from medications administered systemically continues to pose significant challenges to fighting infectious diseases. Ideally, infections would be treated locally for maximal efficacy while minimizing off-target effects. The electrospinning of biomaterials has recently facilitated the creation of electrospun nanofibers as an alternative delivery vehicle for local treatment. This review describes electrospun nanofiber applications to locally target various infectious diseases. Electrospinning is first reviewed as a method to fabricate nanofiber platforms with advantageous properties for developing drug delivery systems. The emergence of artificial intelligence to facilitate the development of nanofiber formulations and the evaluation of operating parameters to customize therapeutic behavior are described. A range of biomaterials utilized for electrospinning nanofibers is summarized in the context of properties suitable for drug delivery, particularly to treat infectious diseases. The current body of literature for electrospun nanofiber applications to tackle infectious diseases, including sexually transmitted infections, oral infections, and Staphylococcus Aureus infections is described. We anticipate that the advantages of electrospun nanofibers to facilitate targeted application while minimizing antibiotic resistance will substantially expand their clinical use in coming years.

Locally administered nanosuspension increases delivery of estradiol for the treatment of vaginal atrophy in mice

Vaginal atrophy affects up to 57% of post-menopausal women, with symptoms ranging from vaginal burning to dysuria. Estradiol hormone replacement therapy may be prescribed to alleviate these symptoms, though many vaginal products have drawbacks including increased discharge and local tissue toxicity due to their hypertonic nature. Here, we describe the development and characterization of a Pluronic F127-coated estradiol nanosuspension (NS) formulation for improved vaginal estradiol delivery. We compare the pharmacokinetics to the clinical comparator vaginal cream (Estrace) and demonstrate increased delivery of estradiol to the vaginal tissue. We utilized ovariectomized (OVX) mice as a murine model of post-menopausal vaginal atrophy and demonstrated equivalent efficacy in vaginal re-epithelialization when dosed with either the estradiol NS or Estrace cream. Further, we demonstrate compatibility of the estradiol NS with vaginal bacteria in vitro. We demonstrate that a Pluronic F127-coated estradiol NS may be a viable option for the treatment of post-menopausal vaginal atrophy.

Can polymeric nanofibers effectively preserve and deliver live therapeutic bacteria?

Probiotics and live therapeutic bacteria (LTB), their strictly regulated therapeutic counterpart, are increasingly important in treating and preventing biofilm-related diseases. This necessitates new approaches to (i) preserve bacterial viability during manufacturing and storage and (ii) incorporate LTB into delivery systems for enhanced therapeutic efficacy. This review explores advances in probiotic and LTB product development, focusing on preservation, protection, and improved delivery. Preservation of bacteria can be achieved by drying methods that decelerate metabolism. These methods introduce stresses affecting viability which can be mitigated with suitable excipients like polymeric or low molecular weight stabilizers. The review emphasizes the incorporation of LTB into polymer-based nanofibers via electrospinning, enabling simultaneous drying, encapsulation, and delivery system production. Optimization of bacterial survival during electrospinning and storage is discussed, as well as controlled LTB release achievable through formulation design using gel-forming, gastroprotective, mucoadhesive, and pH-responsive polymers. Evaluation of the presence of the actual therapeutic strains, bacterial viability and activity by CFU enumeration or alternative analytical techniques is presented as a key aspect of developing effective and safe formulations with LTB. This review offers insights into designing delivery systems, especially polymeric nanofibers, for preservation and delivery of LTB, guiding readers in developing innovative biotherapeutic delivery systems.

Modified vaginal lactobacilli expressing fluorescent and luminescent proteins for more effective monitoring of their release from nanofibers, safety and cell adhesion

Electrospun nanofibers offer a highly promising platform for the delivery of vaginal lactobacilli, providing an innovative approach to preventing and treating vaginal infections. To advance the application of nanofibers for the delivery of lactobacilli, tools for studying their safety and efficacy in vitro need to be established. In this study, fluorescent (mCherry and GFP) and luminescent (NanoLuc luciferase) proteins were expressed in three vaginal lactobacilli (Lactobacillus crispatus, Lactobacillus gasseri and Lactobacillus jensenii) and a control Lactiplantibacillus plantarum with the aim to use this technology for close tracking of lactobacilli release from nanofibers and their adhesion on epithelial cells. The recombinant proteins influenced the growth of the bacteria, but not their ability to produce hydrogen peroxide. Survival of lactobacilli in nanofibers immediately after electrospinning varied among species. Bacteria retained fluorescence upon incorporation into PEO nanofibers, which was vital for evaluation of their rapid release. In addition, fluorescent labelling facilitated efficient tracking of bacterial adhesion to Caco-2 epithelial cells, while luminescence provided important quantitative insights into bacterial attachment, which varied from 0.5 to 50% depending on the species. The four lactobacilli in dispersion or in nanofibers were not detrimental for the viability of Caco-2 cells, and did not demonstrate hemolytic activity highlighting the safety profiles of both bacteria and PEO nanofibers. To summarize, this study contributes to the development of a promising delivery system, tailored for local administration of safe vaginal lactobacilli.

Sexual transmission of urogenital bacteria: whole metagenome sequencing evidence from a sexual network study

Sexual transmission of the urogenital microbiota may contribute to adverse sexual and reproductive health outcomes. The extent of sexual transmission of the urogenital microbiota is unclear as prior studies largely investigated specific pathogens. We used epidemiologic data and whole metagenome sequencing to characterize urogenital microbiota strain concordance between participants of a sexual network study. Individuals who screened positive for genital Chlamydia trachomatis were enrolled and referred their sexual contacts from the prior 60-180 days. Snowball recruitment of sexual contacts continued for up to four waves. Vaginal swabs and penile urethral swabs were collected for whole metagenome sequencing. We evaluated bacterial strain concordance using inStrain and network analysis. We defined concordance as ≥99.99% average nucleotide identity over ≥50% shared coverage; we defined putative sexual transmission as concordance between sexual contacts with <5 single-nucleotide polymorphisms per megabase. Of 138 participants, 74 (54%) were female; 120 (87%) had genital chlamydia; and 43 (31%) were recruited contacts. We identified 115 strain-concordance events among 54 participants representing 25 bacterial species. Seven events (6%) were between sexual contacts including putative heterosexual transmission of Fannyhessea vaginae, Gardnerella leopoldii, Prevotella amnii, Sneathia sanguinegens, and Sneathia vaginalis (one strain each), and putative sexual transmission of Lactobacillus iners between female contacts. Most concordance events (108, 94%) were between non-contacts, including eight female participants connected through 18 Lactobacillus crispatus and 3 Lactobacillus jensenii concordant strains, and 14 female and 2 male participants densely interconnected through 52 Gardnerella swidsinskii concordance events.IMPORTANCEEpidemiologic evidence consistently indicates bacterial vaginosis (BV) is sexually associated and may be sexually transmitted, though sexual transmission remains subject to debate. This study is not capable of demonstrating BV sexual transmission; however, we do provide strain-level metagenomic evidence that strongly supports heterosexual transmission of BV-associated species. These findings strengthen the evidence base that supports ongoing investigations of concurrent male partner treatment for reducing BV recurrence. Our data suggest that measuring the impact of male partner treatment on F. vaginae, G. leopoldii, P. amnii, S. sanguinegens, and S. vaginalis may provide insight into why a regimen does or does not perform well. We also observed a high degree of strain concordance between non-sexual-contact female participants. We posit that this may reflect limited dispersal capacity of vaginal bacteria coupled with individuals' comembership in regional transmission networks where transmission may occur between parent and child at birth, cohabiting individuals, or sexual contacts.

Probiotic significance of Lactobacillus strains: a comprehensive review on health impacts, research gaps, and future prospects

A rising corpus of research has shown the beneficial effects of probiotic Lactobacilli on human health, contributing to the growing popularity of these microorganisms in recent decades. The gastrointestinal and urinary tracts are home to these bacteria, which play a vital role in the microbial flora of both humans and animals. The Lactobacillus probiotic, i.e, Lactobacillus plantarum, Lactobacillus paracasei, Lactobacillus acidophilus, Lactobacillus casei, Lactobacillus rhamnosus, Lactobacillus crispatus, Lactobacillus gasseri, Lactobacillus reuteri, and Lactobacillus bulgaricus, are highly recognized for their remarkable probiotic qualities. The current study aims to highlight the beneficial effects of probiotics in different health conditions, point out the research gap, and highlight the future directives for the safe use of these probiotics in several health issues. Most importantly, we have added the most recent literature related to the characteristics and usage of these probiotics in clinical and pre-clinical settings. Based on the above statement, we believe that this is the first report on the application of probiotics in human diseases. By providing a deeper knowledge of the complex functions these probiotics play in both human and animal health, our analysis will direct future studies and developments in this rapidly developing field.

Mesh and layered electrospun fiber architectures as vehicles for Lactobacillus acidophilus and Lactobacillus crispatus intended for vaginal delivery

Bacterial vaginosis (BV) is a recurrent condition that affects millions of women worldwide. The use of probiotics is a promising alternative or an adjunct to traditional antibiotics for BV prevention and treatment. However, current administration regimens often require daily administration, thus contributing to low user adherence and recurrence. Here, electrospun fibers were designed to separately incorporate and sustain two lactic acid producing model organisms, Lactobacillus crispatus (L. crispatus) and Lactobacillus acidophilus (L. acidophilus). Fibers were made of polyethylene oxide and polylactic-co-glycolic acid in two different architectures, one with distinct layers and the other with co-spun components. Degradation of mesh and layered fibers was evaluated via mass loss and scanning electron microscopy. The results show that after 48 h and 6 days, cultures of mesh and layered fibers yielded as much as 108 and 109 CFU probiotic/mg fiber in total, respectively, with corresponding daily recovery on the order of 108 CFU/(mg·day). In addition, cultures of the fibers yielded lactic acid and caused a significant reduction in pH, indicating a high level of metabolic activity. The formulations did not affect vaginal keratinocyte viability or cell membrane integrity in vitro. Finally, mesh and layered probiotic fiber dosage forms demonstrated inhibition of Gardnerella, one of the most prevalent and abundant bacteria associated with BV, respectively resulting in 8- and 6.5-log decreases in Gardnerella viability in vitro after 24 h. This study provides initial proof of concept that mesh and layered electrospun fiber architectures developed as dissolving films may offer a viable alternative to daily probiotic administration.

Rapid-dissolving electrospun nanofibers for intra-vaginal antibiotic or probiotic delivery

The emergence of probiotics as an alternative and adjunct to antibiotic treatment for microbiological disturbances of the female genitourinary system requires innovative delivery platforms for vaginal applications. This study developed a new, rapid-dissolving form using electrospun polyethylene oxide (PEO) fibers for delivery of antibiotic metronidazole or probiotic Lactobacillus acidophilus, and performed evaluation in vitro and in vivo. Fibers did not generate overt pathophysiology or encourage Gardnerella growth in a mouse vaginal colonization model, inducing no alterations in vaginal mucosa at 24 hr post-administration. PEO-fibers incorporating metronidazole (100 µg MET/mg polymer) effectively prevented and treated Gardnerella infections (∼3- and 2.5-log reduction, respectively, 24 hr post treatment) when administered vaginally. Incorporation of live Lactobacillus acidophilus (107 CFU/mL) demonstrated viable probiotic delivery in vitro by PEO and polyvinyl alcohol (PVA) fibers to inhibit Gardnerella (108 CFU/mL) in bacterial co-cultures (9.9- and 7.0-log reduction, respectively, 24 hr post-inoculation), and in the presence of vaginal epithelial cells (6.9- and 8.0-log reduction, respectively, 16 hr post-inoculation). Administration of Lactobacillus acidophilus in PEO-fibers achieved vaginal colonization in mice similar to colonization observed with free Lactobacillus. acidophilus. These experiments provide proof-of-concept for rapid-dissolving electrospun fibers as a successful platform for intra-vaginal antibiotic or probiotic delivery.