In vivo model of Propionibacterium (Cutibacterium) spp. biofilm in Drosophila melanogaster

Preparation and evaluation the effects of retinoic acid loaded proliposomal nanofibers on microbial biofilm inhibition

The electrospinning method involves the production of different drug delivery systems using various polymers. The production of proliposomes with electrospinning provides the hybridization of two novel drug delivery systems. Retinoic acid, also known as all-trans retinoic acid (ATRA), is a common and effective drug for acne therapy. This study aimed to prepare ATRA-loaded proliposomal nanofibers and evaluate their effectiveness on microbial biofilm inhibition. Blank and ATRA-loaded proliposomal nanofiber formulations were fabricated in various polyvinylpyrrolidone, phosphatidylcholine and cholesterol ratios. TEM images verified the rapid formation of the liposomes after the hydration of nanofibers. The vesicle size, polydispersity index and zeta potential values of self-assembled liposomes were measured. The vesicle size values were found to be 321.9-363.8 nm with PDI values varying between 0.332 and 0.511 and zeta potential values of (-16.8) to (-20.5)mV. ATRA-loaded proliposomal nanofibers provided higher bioadhesion (0.25 mJ/cm2) than the commercial cream (0.07 mJ/cm2). The short-term stability results showed that the initial characteristics remained for three months at 4 °C. The proposed ATRA-loaded self-assembled proliposomal system provided antibacterial, fungistatic or fungicidal effects superior to retinoic acid itself and inhibited biofilm formation in lower concentrations. This approach can combine the stability advantage of nanofibers in the dry state with the high effectiveness of liposomes in acne treatment presenting antibacterial and anti-biofilm-forming activity against Candida albicans and Cutibacterium acnes.

A microRNA focus on acne

Acne (syn. acne vulgaris) is a common inflammatory skin disorder associated with puberty and adolescence. The disease is characterized by comedoneous lesions, papules, pustules, and nodules that are mostly found on the face. These lesions are caused by intricate interactions between the pilosebaceous unit and the Cutibacterium acnes (C. acnes) bacteria. Unhealthy acne and its aftereffects, like pigment changes and scarring, have a detrimental impact on one's quality of life. Recent years have seen a sharp increase in the approval of nucleic acid therapies (NATs), such as antisense oligonucleotides and short-interfering RNA medications, for rare diseases for which there are few or no effective treatments. These developments suggest that NATs may be useful in acne treatment plans down the road, as do clinical trials for microRNA (miRNA) modulation in skin contexts. We highlight promising miRNA targets for anti-acne therapy in this review. We outline the pathophysiology of acne in brief and emphasize the functions of C. acnes. Next, we concentrate on the distinct impacts of biofilm and planktonic C. acnes on a Toll-like receptor 2 axis that spans miR-146a-5p, which was recently discovered. Before discussing the potential contributions of miR-21-5p, miR-233-3p, and miR-150-5p to inflammatory axes in acne, we evaluate miR-146a-5p in sebocytes. Finally, we address patient involvement in miRNA-related acne research and translational perspectives.

The role of biofilm formation in the pathogenesis and antimicrobial susceptibility of Cutibacterium acnes

Cutibacterium acnes (previously known as Propionibacterium acnes) is frequently found on lipid-rich parts of the human skin. While C. acnes is most known for its role in the development and progression of the skin disease acne, it is also involved in many other types of infections, often involving implanted medical devices. C. acnes readily forms biofilms in vitro and there is growing evidence that biofilm formation by this Gram-positive, facultative anaerobic micro-organism plays an important role in vivo and is also involved in treatment failure. In this brief review we present an overview on what is known about C. acnes biofilms (including their role in pathogenesis and reduced susceptibility to antibiotics), discuss model systems that can be used to study these biofilms in vitro and in vivo and give an overview of interspecies interactions occurring in polymicrobial communities containing C. acnes.

Dilemma and a way out for bacterial biofilm research

Biofilm-associated infections (BAIs) are more common in clinical practice and have become a public health problem of global concern. We present our views on current research (detection methods, mechanism research, animal model construction, treatment strategies, etc.) on biofilms and BAIs, and discuss future developments concerning this important issue.

Detailed protocol for germ-free Drosophila melanogaster colonization with Propionibacterium spp. biofilms

In this protocol, we describe a germ-free Drosophila melanogaster model to investigate anaerobic bacterial biofilms. We detail how to establish Propionibacterium spp. biofilms in the fruit fly’s gut using an easy to carry out method.

For complete details on the use and execution of this protocol, please refer to Bronnec and Alexeyev (2021) and Bronnec et al. (2022).

•

Detailed protocol for the generation of germ-free Drosophila melanogaster

•

Oral infection of germ-free fruit flies and Propionibacterium spp. colonization

•

Visualization by microscopy of Propionibacterium spp. biofilms in fruit flies

•

In vivo exposed epithelial cells in low oxygen environment

Propionibacterium (Cutibacterium) granulosum Extracellular DNase BmdE Targeting Propionibacterium (Cutibacterium) acnes Biofilm Matrix, a Novel Inter-Species Competition Mechanism

Acne vulgaris is the most common dermatological disorder worldwide affecting more than 80% of adolescents and young adults with a global prevalence of 231 million cases in 2019. The involvement of the skin microbiome disbalance in the pathophysiology of acne is recognized, especially regarding the relative abundance and diversity of Propionibacterium acnes a well-known dominant human skin commensal. Biofilms, where bacteria are embedded into a protective polymeric extracellular matrix, are the most prevalent life style for microorganisms. P. acnes and its biofilm-forming ability is believed to be a contributing factor in the development of acne vulgaris, the persistence of the opportunistic pathogen and antibiotic therapy failures. Degradation of the extracellular matrix is one of the strategies used by bacteria to disperse the biofilm of competitors. In this study, we report the identification of an endogenous extracellular nuclease, BmdE, secreted by Propionibacterium granulosum able to degrade P. acnes biofilm both in vivo and in vitro. This, to our knowledge, may represent a novel competitive mechanism between two closely related species in the skin. Antibiotics targeting P. acnes have been the mainstay in acne treatment. Extensive and long-term use of antibiotics has led to the selection and spread of resistant bacteria. The extracellular DNase BmdE may represent a new bio-therapeutical strategy to combat P. acnes biofilm in acne vulgaris.