Photon Factory Activity Report 2004 #22 Part B (2005)
Biological Science

15A/2003G142

Study on two intercellular lipid lamellar structures in stratum corneum
Ichiro Hatta1, Hiroshi Takahashi2, Noboru Ohta3
1
Fukui University of Technology, Fukui 910-8505, Japan2
Department of Physics, Gunma University, Maebashi, 371-8510, Japan
3
Japan Synchrotron Radiation Research Institute (JASRI/SPring-8), Hyogo 679-5198, JapanThe outermost layer of skin, the stratum corneum(SC), is composed of keratinized cells called corneocytes
and intercellular lipids. The flattened corneocytes areembedded in the intercellular lipid matrix. The lipid
matrix works not only as the main barrier but also
pathways for water, drugs, etc. A molecular structural
study of the intercellular lipid assembly is highly desired
to solve their molecular mechanism. The intercellularlipid assembly forms lamellar structures.
By the SAXD study on mammalian SCs the longlamellar structure with the repeat distance of about 13 nm
has been observed dominantly and the short lamellar
structure with the repeat distance of about 6 nm also has
been observed although sometimes the diffraction1
intensity is weak. Bouwstra et al. have claimed that since
the long lamellar structure present in all species examineduntil now has a characteristic molecular organization
within framework of their speculation, the structure
seems to play an important role in skin barrier function.
However, from the SAXD study on hairless mouse
SC performed by BL 15A we have found that withincreasing water content in SC the diffraction peak
positions for the first to the fifth order diffraction for thelong lamellar structure are almost unchanged in1
consistent with the result of Bouwstra et al. while thepositions of the first and the second order diffraction forthe short lamellar structure markedly shifts towards the2lower angle , suggesting that the short lamellar structure
exhibits swelling against the water content in SC. This is
the first evidence for the swelling behavior in SC.
Furthermore, we found that the widths of thediffraction profile of both the long lamellar and the shortlamellar structures become narrow simultaneously at thewater content of about 20-30 wt%. This result indicatesthat the long and the short lamellar structures interact
with each other and as a result, when the short lamellar
structure swells, the both long and short lamellar
structures are stabilized simultaneously at the watercontent of 20-30 wt%. Here it should be stressed that in
SC almost all water is stored in the corneocytes, but asmall part of water stays in the water layer of the shortlamellar structure. The amount of water in the water layer
is very little but plays an important role in regulation of
the water content in SC.

Based upon the above result we propose that theinteraction of the long and the short lamellar structures
works in functioning in SC, e. g., sine the long lamellar
structure has hydrophobic character and the short lamellar
structure has hydrophilic character the transport ofmolecules in SC takes place through the favorable
structure and is regulated by the counter structure. To
carry out this study further it is quite important to find acondition that we can always observe the diffraction
profile of the short lamellar structure in SC. However atpresent we could not find out the condition yet. Recently
the existence of the short lamellar structure has been
3
confirmed by neutron diffraction study. Under thecondition that SC is hydrated by heavy water, thediffraction only for the short lamellar structure has been
observed notwithstanding the considerably broad profile.
Furthermore indirectly the swelling of the short lamellarstructure
hasbeenobserved
although
theCharalambopoulou et al. has not stressed this fact. In thefurther structural study on SC it is useful to use SAXD
and neutron diffraction.

References[1] J. A. Bouwstra, P. L. Honeywell-Nguyen, G. S. Gooris
and M. Ponec, Progr. Lipid Res. 42, 1 (2003).
[2] N. Ohta, S. Ban, H. Tanaka, S. Nakata and I. Hatta,
Chem. Phys. Lipids 123, 1 (2003).
[3] G. Ch. Charalambopoulou, Th. A. Steriotis, Th. Hauss,
A. K. Stubos and N. K. Kanellopoulos, Physica B 350,
e603 (2004).

hatta@fukui-ut.ac.jp

Users' Report247