High bacterial colonization and lipase activity in microcomedones

• Published in: Experimental dermatology 2020-02, Vol.29 (2), p.168-176
• Main Authors: Josse, Gwendal, Mias, Céline, Le Digabel, Jimmy, Filiol, Jérôme, Ipinazar, Célia, Villaret, Aurélie, Gomiero, Caroline, Bevilacqua, Marc, Redoules, Daniel, Nocera, Thérèse, Saurat, Jean‐Hilaire, Gontier, Etienne
• Format: Article
• Language: English
• Subjects: Acne; Acne vulgaris; Acne Vulgaris - diagnostic imaging; Acne Vulgaris - enzymology; Acne Vulgaris - microbiology; Bacteria; Colonization; electron microscopy; fluorescence; Fluorescence spectroscopy; Fourier analysis; fourier transform infrared; hair follicle; Hair Follicle - microbiology; Humans; Inflammation; Lipase; Lipase - metabolism; Lipids; Microscopy; Microscopy, Electron, Scanning; Microscopy, Electron, Transmission; Microscopy, Fluorescence, Multiphoton; multiphoton microscopy; Original; Porphyrins - metabolism; Propionibacterium acnes; Scanning electron microscopy; Spectrum analysis; Transmission electron microscopy; Ultrastructure
• ISSN: 0906-6705; 1600-0625
• DOI: 10.1111/exd.14069

Background Although acne vulgaris has a multifactorial aetiology, comedogenesis and bacteria colonization of the pilosebaceous unit are known to play a major role in the onset of inflammatory acne lesions. However, many aspects remain poorly understood such as where and when is the early stage of the Propionibacterium acnes colonization in follicular unit? Our research aimed at providing a precise analysis of microcomedone's structure to better understand the interplay between Propionibacterium acnes and follicular units, and therefore, the role of its interplay in the formation of acne lesions. Methods Microcomedones were sampled using cyanoacrylate skin surface stripping (CSSS). Their morphology was investigated with multiphoton imaging and their ultrastructure with scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Bacterial lipase activity in the microcomedones was quantified using a dedicated enzymatic test as well as a Fourier Transform Infra‐Red (FTIR) analysis. The porphyrin produced by bacteria was analysed with HPTLC and fluorescence spectroscopy. Results The imaging analysis showed that microcomedones' structure resembles a pouch, whose interior is mostly composed of lipids with clusters of bacteria and whose outer shell is made up of corneocyte layers. The extensive bacteria colonization is clearly visible using TEM. Even after sampling, clear lipase activity was still seen in the microcomedone. A high correlation, r = .85, was observed between porphyrin content measured with HPTLC and with fluorescence spectroscopy. These observations show that microcomedones, which are generally barely visible clinically, already contain a bacterial colonization.