Mechanisms and Implications of Bacterial Invasion across the Human Skin Barrier - PubMed
Source : https://pubmed.ncbi.nlm.nih.gov/35532353/
Atopic dermatitis (AD) is associated with a deficiency of skin lipids, increased populations of Staphylococcus aureus in the microbiome, and structural defects in the stratum corneum (SC), the outermost layer of human skin. However, the pathogenesis of AD is ambiguous, as it is unclear whether obser ...
Results reveal for the first time that S. aureus can be internalized by corneocytes, indicating transcellular movement through the tissue during permeation, consistent with previous theoretical models. S. aureus also degrades the mechanical integrity of human SC, particularly when the tissue is partially depleted of lipids. These observed mechanical changes are likely the cause of broken or ruptured tissue seen as exudative lesions in AD flares. This work further highlights the necessity of lipids in skin microbial barrier function.
• Source: Microbiology Spectrum
• Conclusion. “When coupled with delipidated AD tissue conditions, bacterial permeation can also explain increased tissue fragility, potentially causing lesion formation in AD patients that results in further enhancing bacterial permeability across the stratum corneum and the development of chronic conditions.”
• Previous work has demonstrated that S. aureus can cross stratum corneum (SC) tissue when lipids are depleted akin to AD conditions.
• In this preclinical study, researchers found that S. aureus can be internalized by corneocytes, thus suggesting transcellular movement through the tissue during permeation. Furthermore, S. aureus degrades the mechanical integrity of human stratum corneum—especially when depleted of lipids. These changes lead to broken or ruptured tissue which is exhibited by exudative lesions in atopic dermatitis flare-ups. This study stresses the importance of lipids in skin microbial barrier function.
• “S. aureus does not produce any ceramidase, nor has this bacterial species previously been shown to alter stratum corneum lipids directly. Nonetheless, the impact of bacterial growth and permeation on skin shows changes in the mechanical properties of SC consistent with lipid depletion: a stiffening and weakening of the tissue. This seems, therefore, to suggest that the bacteria may potentially be altering other components of the tissue. The most likely alternative is that bacteria are affecting NMFs and/or hyaluronan, either directly through enzyme degradation or indirectly, for NMFs, by leaching out of the cornified envelope during cellular internalization,” wrote the authors.