Chika Katagiri

Changes in environmental humidity affect the water-holding property of the stratum corneum and its free amino acid content, and the expression of filaggrin in the epidermis of hairless mice

BACKGROUND Seasonal changes affect the condition of skin and may trigger various cutaneous disorders. OBJECTIVE To clarify the effects of the environmental humidity on the skin pathology, we studied the effects of the humidity on a water-holding function of the stratum corneum. METHODS We evaluated the skin surface conductance, amino acid in the stratum corneum, and immunoreactivity of filaggrin of the epidermis of hairless mice kept in different environmental humidity. RESULTS Skin surface conductance in the stratum corneum of hairless mice 3-7 days after transfer from a humid environment (>80% relative humidity) to a dry (<10% relative humidity) environment, was significantly lower than that of the mice transferred from a normal environment (relative humidity=40-70%) to a dry environment. The free amino acid content in the stratum corneum significantly decreased 24 h after we transferred the mice from a normal to a dry condition, then it recovered to the original level within 3 days, while the mice transferred from a humid to a dry condition showed a significantly lower amino acid content even 7 days after the transfer. No obvious change was observed in the relative composition of the major components of the free amino acids during the experiments. Immunoreactivity of filaggrin, which is the main precursor of free amino acids in the stratum corneum, also became faint in the epidermis of the mice transferred from a humid or normal to a dry environment. CONCLUSION These results suggested that a drastic decrease in the environmental humidity reduced the total free amino acid generation and consequently induced skin surface dryness in the stratum corneum.

S100A8/A9, a key mediator for positive feedback growth stimulation of normal human keratinocytes

S100A8 and S100A9 are known to be up‐regulated in hyperproliferative and psoriatic epidermis, but their function in epidermal keratinocytes remains largely unknown. Here we show that (1) S100A8 and S100A9 are secreted by cultured normal human keratinocytes (NHK) in a cytokine‐dependent manner, (2) when applied to NHK, recombinant S100A8/A9 (a 1:1 mixture of S100A8 and S100A9) induced expression of a number of cytokine genes such as IL‐8/CXCL8, CXCL1, CXCL2, CXCL3, CCL20, IL‐6, and TNFα that are known to be up‐regulated in psoriatic epidermis, (3) the S100A8/A9‐induced cytokines in turn enhanced production and secretion of S100A8 and S100A9 by NHK, and (4) S100A8 and S100A8/A9 stimulated the growth of NHK at a concentration as low as 1 ng/ml. These results indicate the presence of a positive feedback loop for growth stimulation involving S100A8/A9 and cytokines in human epidermal keratinocytes, implicating the relevance of the positive feedback loop to the etiology of hyperproliferative skin diseases, including psoriasis. J. Cell. Biochem. 104: 453–464, 2008.

Purification and characterization of active caspase‐14 from human epidermis and development of the cleavage site‐directed antibody

Restricted expression of caspase‐14 in differentiating keratinocytes suggests the involvement of caspase‐14 in terminal differentiation. We purified active caspase‐14 from human cornified cells with sequential chromatographic procedures. Specific activity increased 764‐fold with a yield of 9.1%. Purified caspase‐14 revealed the highest activity on WEHD‐methylcoumaryl‐amide (MCA), although YVAD‐MCA, another caspase‐1 substrate, was poorly hydrolyzed. The purified protein was a heterodimer with 17 and 11 kDa subunits. N‐terminal and C‐terminal analyses demonstrated that the large subunit consisted of Ser6‐Asp146 and N‐terminal of small subunit was identified as Lys153. We successfully developed an antiserum (anti‐h14D146) directed against the Asp146 cleavage site, which reacted only with active caspase‐14 but not with procaspase‐14. Furthermore we confirmed that anti‐h14D146 did not show any reactivity to the active forms of other caspases. Immunohistochemical analysis demonstrated that anti‐h14D146 staining was mostly restricted to the cornified layer and co‐localized with some of the TUNEL positive‐granular cells in the normal human epidermis. UV radiation study demonstrated that caspase‐3 was activated and co‐localized with TUNEL‐positive cells in the middle layer of human epidermis. In contrast, we could not detect caspase‐14 activation in response to UV. Our study revealed tightly regulated action of caspase‐14, in which only the terminal differentiation of keratinocytes controls its activation process. J. Cell. Biochem. 109: 487–497, 2010.

Crystal structure of SCCA1 and insight about the interaction with JNK1.

Squamous cell carcinoma antigen 1 (SCCA1), which belongs to serine proteinase inhibitor (serpin) superfamily, inhibits papain-like cysteine proteinase. Recently, it has been reported that SCCA1 acts not only as a proteinase inhibitor but also as an inhibitor of UV-induced apoptosis via suppression of the activity of c-Jun NH(2)-terminal kinase (JNK1). The present study determined the crystal structure of SCCA1, suggesting that the reactive center loop (RCL) of SCCA1, a recognition site of proteinase, is very flexible and located away form the main-body of SCCA1. We show that the inhibitory effect of SCCA1 on the kinase activity of JNK1 is lost when the RCL was truncated. Furthermore, we found that a mutant protein created by replacing one amino acid in RCL maintain the suppressive activity to JNK1, whereas the inhibitory effect to proteinase is obviously decreased.

Up-regulation of serpin SCCA1 is associated with epidermal barrier disruption

BACKGROUND Parakeratosis, the persistent presence of nuclei in the stratum corneum (SC) is associated with serious disruption of skin barrier function. Squamous cell carcinoma antigen 1 (SCCA1) is strongly up-regulated in inflamed and parakeratotic skin. OBJECTIVE To find a biochemical marker for the SC barrier disruption, especially the disruption associated with parakeratosis. METHODS An ELISA assay system was established to quantify SCCA1 in the extract of tape-stripped cornified cells. Transepidermal water loss (TEWL) and other skin parameters were measured and compared with the amount of SCCA1. Localization of SCCA1 was investigated immunohistochemically in various skin diseases with parakeratosis. Nuclei and SCCA1 on the skin surface were detected by staining of corniocytes collected on an adhesive-coated slide glass. RESULTS SCCA1 showed strong up-regulation in lesional skin with psoriasis (466-fold), hayfever skin caused by Japanese ceder pollen (232-fold) and sun-exposed skin of healthy individuals (90-fold) compared to their normal sun-protected skin. The increased levels of SCCA1 were well correlated with increased values of TEWL and the number of parakeratotic cells in the SC. Furthermore, subjects with high levels of SCCA1 in the epidermis were more susceptible to barrier disruption by external stimuli, and this was accompanied with a further increase of SCCA1. We confirmed that localization of SCCA1 was limited to parakeratotic areas by using the skin surface staining technique. Immunohistochemical study also demonstrated that SCCA1 was always present at high levels in parakeratotic epidermis. CONCLUSION All of our findings indicate that SCCA1 plays an important role in the induction of epidermal barrier disruption. SCCA1 may be a critical determinant of barrier function in the epidermis.

Evaluation of psychological stress in confined environments using salivary, skin, and facial image parameters

Detecting the influence of psychological stress is particularly important in prolonged space missions. In this study, we determined potential markers of psychological stress in a confined environment. We examined 23 Japanese subjects staying for 2 weeks in a confined facility at Tsukuba Space Center, measuring salivary, skin, and facial image parameters. Saliva was collected at four points in a single day to detect diurnal variation. Increases in salivary cortisol were detected after waking up on the 4th and 11th days, and at 15:30 on the 1st and in the second half of the stay. Transepidermal water loss (TEWL) and sebum content of the skin were higher compared with outside the facility on the 4th and 1st days respectively. Increased IL-1β in the stripped stratum corneum was observed on the 14th day, and 7 days after leaving. Differences in facial expression symmetry at the time of facial expression changes were observed on 11th and 14th days. Thus, we detected a transition of psychological stress using salivary cortisol profiles and skin physiological parameters. The results also suggested that IL-1β in the stripped stratum corneum and facial expression symmetry are possible novel markers for conveniently detecting psychological stress.

In vivo optical interferometric imaging of human skin utilizing monochromatic light source.

We have demonstrated tomographic imaging of in vivo human skin with an optical interferometric imaging technique using a monochromatic light source. The axial resolution of this method is determined by the center wavelength and the NA of the objective and is irrelevant to the bandwidth of the light source in contrast to optical coherence tomography. Our imaging system is constructed with low-priced and small-sized compact disk optical pickup components, a laser diode, a high NA objective, and a voice coil actuator. In spite of its low cost and small size, our imaging system can visualize the structure of human skin as clearly as a commercial reflectance confocal microscope.

Serpin squamous cell carcinoma antigen inhibits UV-induced apoptosis via suppression of c-JUN NH2-terminal kinase

Katagiri et al. 2006. J. Cell Biol. doi:10.1083/jcb.200508064 [OpenUrl][1][Abstract/FREE Full Text][2] [1]: {openurl}?query=rft_id%253Dinfo%253Adoi%252F10.1083%252Fjcb.200508064%26rft_id%253Dinfo%253Apmid%252F16549498%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%