| AVS 60th International Symposium and Exhibition | |
| Biomaterial Interfaces | Wednesday Sessions |
| Session BI+AI+AS+BA+IA+NL+NS+SP-WeA |
| Session: | Characterization of Biointerfaces |
| Presenter: | J.S. Hammond, Physical Electronics Inc. |
| Authors: | I. Ishizaki, ULVAC-PHI, Inc., Japan J.S. Hammond, Physical Electronics Inc. A. Kubo, Keio University, Japan H. Kawasaki, Keio University, Japan K. Nagao, Keio University, Japan Y. Ohashi, ULVAC-PHI, Inc., Japan M. Amagai, Keio University, Japan A. Kubo, Keio University, Japan |
| Correspondent: | Click to Email |
The stratum corneum (SC) is the outermost barrier protecting the mammalian body from desiccation and foreign insults. Congenital SC barrier insufficiencies, i.e., filaggrin deficiency, are hypothesized to predispose patients to atopic diseases. The insoluble nature of the SC has hampered in-depth-analysis of its barrier function by conventional cell biological methods. Here, we applied time-of-flight secondary-ion-mass-spectrometry (TOF-SIMS) imaging technology to analyze the SC in skin sections of wild type and filaggrin knockout mice.
TOF-SIMS enabled the visualization of the distribution of natural substances and the infiltration of externally applied molecules directly without any staining procedure. The distribution of potassium (K) and arginine revealed that the SC consists of three sharply demarcated layers. K was concentrated in the upper layer, while arginine, a major component of the filaggrin-derived natural moisturizing factors, was specifically concentrated in the middle layer and markedly decreased in the filaggrin knockout SC. When skin was soaked in water, K of the upper layer disappeared. When the mice tails were soaked in solutions of K or hexavalent chromium before cross-sectioning, the TOF-SIMS line scan data indicates that the upper layer of the SC allowed the influx of these ions, suggesting that this layer acts like a “sponge” allowing the passive influx and efflux of exogenous ions. The middle layer blocked the influx of K and hexavalent chromium ions, but failed to block the influx of trivalent chromium ions, which was blocked at the lower layer. Therefore the middle and lower layers have distinct barrier properties depending on each metal. Filaggrin deficiency resulted in the abrogation of the lower layer barrier, allowing trivalent chromium to permeate through the SC to viable epidermal layers. These results, obtained by TOF-SIMS analyses, reveal that the SC consists of three layers of distinct functional properties and demonstrate the loss of barrier properties for particular metal ions in filaggrin deficient SC samples.