Cutibacterium acnes regulates the epidermal barrier properties of HPV-KER human immortalized keratinocyte cultures

Abstract

our skin provides a physical barrier to separate the internal part of our body from the environment. Maintenance of complex barrier functions is achieved through anatomical structures in the skin, the stratified squamous epithelium specialized junctional organelles, called tight junctions (TJs). Several members of our microbial communities are known to affect the differentiation state and function of the colonized organ. Whether and how interactions between skin cells and cutaneous microbes, including Cutibacterium acnes (C. acnes), modify the structure and/or function of our skin is currently only partly understood. Thus, in our studies, we investigated whether C. acnes may affect the epidermal barrier using in vitro model systems. Real-time cellular analysis showed that depending on the keratinocyte differentiation state, the applied C. acnes strains and their dose, the measured impedance values change, together with the expression of selected TJ proteins. These may reflect barrier alterations, which can be partially restored upon antibiotic-antimycotic treatment. Our findings suggest that C. acnes can actively modify the barrier properties of cultured keratinocytes, possibly through alteration of tight cell-to-cell contacts. Similar events may play important roles in our skin, in the maintenance of cutaneous homeostasis. One of the most important properties of our skin is the complex barrier it provides to separate the internal part of our body from the environment, limiting contact with harmful chemicals, microbes, allergens and radiation 1-3. The major building blocks of the skin barrier are the keratinocytes, which are capable of recognizing the everchanging environmental conditions and mounting appropriate responses to maintain the integrity of the human body 4,5. Maintenance of complex barrier functions is achieved through anatomical structures in the skin. The stratified squamous epithelium is the uppermost skin layer that contains live keratinocytes and contains specialized junctional organelles, called tight junctions (TJs), which are localized between the cells of the second and third layer of the stratum granulosum 6. TJs provide intimate links between adjacent cells and play major roles in establishing the epidermal barrier, as well as act as important determinants of transepidermal transport 7-9. The complex, multi-protein structure of TJs includes more than 40 proteins 10,11. Claudin (CLDN) protein family members are some of the most important TJ components, as they are critical for the regulation of barrier functions, including permselectivity, which determines the size, ionic charge and electric resistance of molecules that may be transported through the barrier 12,13. Keratinocytes are also in constant contact with various members of the cutaneous microbiota. One of the most well-known members of this community is the Cutibacterium acnes (C. acnes) bacterium, which, beginning with puberty, is a dominant species and preferentially inhabits sebum-rich skin regions 14,15. Current research is eluci...

Human Skin Microbiome: Impact of Intrinsic and Extrinsic Factors on Skin Microbiota

“…C. acnes is, directly and indirectly, involved in the pathogenesis of the common inflammatory skin disease—acne vulgaris. The free fatty acids and the pro-inflammatory virulence factors—porphyrins, produced by these bacteria, can cause skin inflammation [ 23 , 28 , 29 ].…”

Associations of the skin, oral and gut microbiome with aging, frailty and infection risk reservoirs in older adults

“…8a,b and Supplementary Table 4; Kruskal-Wallis test P < 0.05 and log 10 Linear Discriminant Analysis score (LDA) > 2.0). C. acnes is a ubiquitous commensal skin microbe, dominant in oily skin sites in younger adults 29 with key roles in immunomodulation, epithelial barrier maintenance and protecting the host from pathogens as well as acne vulgaris [49][50][51][52] . At oily sites, Streptococcus parasanguinis was significantly enriched in SNFD, whereas Propionibacterium namnetense was significantly θ = 1 represents 100% similarity in shared species and their relative abundance; θ = 0 indicates no (0%) similarity.…”

Barrier function‐related genes and proteins have an altered expression in acne‐involved skin

“…Indeed, the data of Nograles et al 42 support this theory as IL‐17 and IFN‐γ treatment caused significant downregulation of FLG, KRTs, CLDN1, DSGs and DSCs in primary human keratinocytes. In addition, Bruewer et al 43 demonstrated that the pro‐inflammatory cytokines IFN‐γ and TNF‐α can disrupt the properties of the epithelial barrier, while a recent study conducted by Bolla et al 44 suggests that Cutibacterium acnes might impact the skin barrier properties by activating innate immune responses and inducing inflammation. However, on the other hand, sebum lipids are also potential candidates as reflected in the term sebaceous immunobiology 45,46 .…”