Aberrant Lipid Organization in Stratum Corneum of Patients with Atopic Dermatitis and Lamellar Ichthyosis

Center for Electron Microscopy, Leiden University Medical Center, Leiden, the Netherlands.
Journal of Investigative Dermatology (Impact Factor: 6.37). 08/2001; 117(3):710-717. DOI: 10.1046/j.0022-202x.2001.01455.x

ABSTRACT There are several skin diseases in which the lipid composition in the intercellular matrix of the stratum corneum is different from that of healthy human skin. It has been shown that patients suffering from atopic dermatitis have a reduced ceramide content in the stratum corneum, whereas in the stratum corneum of lamellar ichthyosis patients, the amount of free fatty acids is decreased and the ceramide profile is altered. Both patient groups also show elevated levels of transepidermal water loss indicative of an impaired barrier function. As ceramides and free fatty acids are essential for a proper barrier function, we hypothesized that changes in the composition of these lipids would be reflected in the lipid organization in stratum corneum of atopic dermatitis and lamellar ichthyosis patients. We investigated the lateral lipid packing using electron diffraction and the lamellar organization using freeze fracture electron microscopy. In atopic dermatitis stratum corneum, we found that, in comparison with healthy stratum corneum, the presence of the hexagonal lattice (gel phase) is increased with respect to the orthorhombic packing (crystalline phase). In lamellar ichthyosis stratum corneum, the hexagonal packing was predominantly present, whereas the orthorhombic packing was observed only occasionally. This is in good agreement with studies on stratum corneum lipid models that show that the presence of long-chain free fatty acids is involved in the formation of the orthorhombic packing. The results of this study also suggest that the ceramide composition is important for the lateral lipid packing. Finally, using freeze fracture electron microscopy, changes in the lamellar organization in stratum corneum of both patient groups could be observed.Keywords: ceramides, cryoelectron microscopy, diseased human skin, electron diffraction, freeze fracture

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Available from: Gonneke S.K. Pilgram, May 15, 2014
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    • "In contrast, no differences in permeability were found at day 7. When considering the lipid chain packing, electron diffraction showed a higher proportion of hexagonal compared to orthorhombic lateral chain packing in AD patients (Pilgram et al., 2001). However, we were unable to confirm this finding as our in vitro constructs generally did not form the orthorhombic lipid lattice. "
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    ABSTRACT: Mutations in the filaggrin gene (FLG) are strongly associated with common dermatological disorders such as atopic dermatitis. However, the exact underlying pathomechanism is still ambiguous. Here, we investigated the impact of FLG on skin lipid composition, organization and skin acidification using a FLG knock down (FLG-) skin construct. Initially, sodium/hydrogen antiporter (NHE-1) activity was sufficient to maintain the acidic pH (5.5) of the reconstructed skin. At day 7, the FLG degradation products urocanic (UCA) and pyrrolidone-5-carboxylic acid (PCA) were significantly decreased in the FLG- but the skin surface pH was still physiological due to an upregulation of NHE-1. At day 14, secretory phospholipase A2 (sPLA2) IIA, which is converting phospholipids to fatty acids, was significantly more activated in the FLG- than in FLG+. Although NHE-1 and sPLA2 were able to compensate the FLG deficiency, maintain the skin surface pH and ensured ceramide processing (no differences detected), an accumulation of free fatty acids (twofold increase) led to less ordered intercellular lipid lamellae and higher permeability of the FLG- constructs. The interplay of the UCA/PCA and the sPLA2/NHE-1 acidification pathways of the skin and the impact of FLG insufficiency on skin lipid composition and organization in reconstructed skin are described.Journal of Investigative Dermatology accepted article preview online, 23 September 2013. doi:10.1038/jid.2013.402.
    Journal of Investigative Dermatology 09/2013; 134(3). DOI:10.1038/jid.2013.402 · 6.37 Impact Factor
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    • "Dysfunction of the skin barrier in AD can occur through both genetic and acquired mechanisms. For example, AD subjects may have a loss-of-function mutation in filaggrin (Cork et al., 2006; Palmer et al., 2006; Howell et al., 2009), epidermal lipid abnormalities (Murata et al., 1996; Imokawa, 2001; Pilgram et al., 2001), altered protease activity (Cork et al., 2006; Vasilopoulos et al., 2007), more alkaline surface pH (Elias et al., 2008), and a defect in tight junction (TJ) function (De Benedetto et al., 2011), all of which can contribute to decreased skin barrier function. The human epidermis is a multilayered structure that is made up of four progressively differentiated layers. "
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    ABSTRACT: Atopic dermatitis (AD) is characterized by epidermal tight junction (TJ) defects and a propensity for Staphylococcus aureus skin infections. S. aureus is sensed by many pattern recognition receptors, including Toll-like receptor 2 (TLR2). We hypothesized that an effective innate immune response will include skin barrier repair, and that this response is impaired in AD subjects. S. aureus-derived peptidoglycan (PGN) and synthetic TLR2 agonists enhanced TJ barrier and increased expression of TJ proteins, claudin-1 (CLDN1), claudin-23 (CLDN23), occludin, and Zonulae occludens 1 (ZO-1) in primary human keratinocytes. A TLR2 agonist enhanced skin barrier recovery in human epidermis wounded by tape stripping. Tlr2(-/-) mice had a delayed and incomplete barrier recovery following tape stripping. AD subjects had reduced epidermal TLR2 expression as compared with nonatopic subjects, which inversely correlated (r=-0.654, P=0.0004) with transepidermal water loss (TEWL). These observations indicate that TLR2 activation enhances skin barrier in murine and human skin and is an important part of a wound repair response. Reduced epidermal TLR2 expression observed in AD patients may have a role in their incompetent skin barrier.Journal of Investigative Dermatology advance online publication, 6 December 2012; doi:10.1038/jid.2012.437.
    Journal of Investigative Dermatology 12/2012; 133(4). DOI:10.1038/jid.2012.437 · 6.37 Impact Factor
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    • "It appears that ionizing radiation damage in the skin is somewhat similar to atopic dermatitis. Atopic dermatitis, a common form of eczema, affects up to 20% of children in the United States, and is widely accepted to have a profound effect on the stratum corneum function, and increased transepidermal water loss (Murata et al., 1996; Laughter et al., 2000; Imokawa, 2001; Pilgram et al., 2001; Choi and Maibach, 2005; Jungersted et al., 2008). Atopic dermatitis patients are far more susceptible to skin infections by organisms such as Staphlococcus aureus and Herpes simplex virus (Scott et al., 2007; Kedzierska et al., 2008; Lebre et al., 2008; Niebuhr et al., 2008). "
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    ABSTRACT: Skin changes caused by ionizing radiation have been scientifically documented since 1902. Ionizing radiation is a widely accepted form of treatment for various types of cancer. Despite the technological advances, radiation skin injury remains a significant problem. This injury, often referred to as radiation dermatitis, occurs in about 95% of patients receiving radiation therapy for cancer, and ranges in severity from mild erythema to moist desquamation and ulceration. Ionizing radiation is not only a concern for cancer patients, but also a public health concern because of the potential for and reality of a nuclear and/or radiological event. Recently, the United States has increased efforts to develop medical countermeasures to protect against radiation toxicities from acts of bioterrorism, as well as cancer treatment. Management of radiation dermatitis would improve the therapeutic benefit of radiation therapy for cancer and potentially the mortality expected in any "dirty bomb" attack. Currently, there is no effective treatment to prevent or mitigate radiation skin injury. This review summarizes "the good, the bad, and the ugly" of current and evolving knowledge regarding mechanisms of and treatments for radiation skin injury.
    Journal of Investigative Dermatology 01/2012; 132(3 Pt 2):985-93. DOI:10.1038/jid.2011.411 · 6.37 Impact Factor
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