High bacterial colonization and lipase activity in microcomedones.

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.

Raman characterization of human skin aging.

BACKGROUND: Skin aging is a complex biological process mixing intrinsic and extrinsic factors, such as sun exposure. At the molecular level, skin aging affects in particular the extracellular matrix proteins. MATERIALS AND METHODS: Using Raman imaging, which is a nondestructive approach appropriate for studying biological samples, we analyzed how aging modifies the matrix proteins of the papillary and reticular dermis. Biopsies from the buttock and dorsal forearm of volunteers younger than 30 and older than 60 were analyzed in order to identify chronological and photoaging processes. Analyses were performed on skin section, and Raman spectra were acquired separately on the different dermal layers. RESULTS: We observed differences in dermal matrix structure and hydration state with skin aging. Chronological aging alters in particular the collagen of the papillary dermis, while photoaging causes a decrease in collagen stability by altering proline and hydroxyproline residues in the reticular dermis. Moreover, chronological aging alters glycosaminoglycan content in both dermal compartments. CONCLUSION: Alterations of the papillary and reticular dermal matrix structures during photo- and chronological aging were clearly depicted by Raman spectroscopy.

Visualization of dendritic cells' responses in atopic dermatitis: Preventing effect of emollient.

Atopic dermatitis (AD) is a chronic and multifactorial inflammatory skin disease involving various dendritic cells such as epidermal Langerhans cells (LC) and inflammatory dendritic epidermal cells (IDECs). Most of the clinical studies was performed on isolated cells, and thus, it would be useful to characterize directly on the human epidermal tissue the first cellular events occurred during the AD. The suction blister method was used to obtain whole epidermis samples and interstitial cutaneous fluids. Employing multiphoton microscopy, we analyzed the early dynamic behavior of inflammatory cells using Dermatophagoides pteronyssinus atopy patch test (Derp-APT) and evaluated the effects of emollient pre-application. Derp-APT application provoked rapid and strong infiltration of IDECs, and proliferation and activation of LC in the AD subjects' epidermis. Moreover, emollient pre-application strengthened the defective skin barrier and had positive effects on inflammatory cells' behavior, characterized by the complete inhibition of IDEC influx and the presence of immature LC.

Adipose tissue endothelial cells from obese human subjects: differences among depots in angiogenic, metabolic, and inflammatory gene expression and cellular senescence.

OBJECTIVE: Regional differences among adipose depots in capacities for fatty acid storage, susceptibility to hypoxia, and inflammation likely contribute to complications of obesity. We defined the properties of endothelial cells (EC) isolated from subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT) biopsied in parallel from obese subjects. RESEARCH DESIGN AND METHODS: The architecture and properties of the fat tissue capillary network were analyzed using immunohistochemistry and flow cytometry. CD34(+)/CD31(+) EC were isolated by immunoselection/depletion. Expression of chemokines, adhesion molecules, angiogenic factor receptors, as well as lipogenic and senescence-related genes were assayed by real-time PCR. Fat cell size and expression of hypoxia-dependent genes were determined in adipocytes from both fat depots. RESULTS: Hypoxia-related genes were more highly expressed in VAT than SAT adipocytes. VAT adipocytes were smaller than SAT adipocytes. Vascular density and EC abundance were higher in VAT. VAT-EC exhibited a marked angiogenic and inflammatory state with decreased expression of metabolism-related genes, including endothelial lipase, GPIHBP1, and PPAR gamma. VAT-EC had enhanced expression of the cellular senescence markers, IGFBP3 and γ-H2AX, and decreased expression of SIRT1. Exposure to VAT adipocytes caused more EC senescence-associated ß-galactosidase activity than SAT adipocytes, an effect reduced in the presence of vascular endothelial growth factor A (VEGFA) neutralizing antibodies. CONCLUSIONS: VAT-EC exhibit a more marked angiogenic and proinflammatory state than SAT-EC. This phenotype may be related to premature EC senescence. VAT-EC may contribute to hypoxia and inflammation in VAT.