%0 Journal Article
%T Differences in the Histopathology and  Cytokine Expression Pattern between  Chronological Aging and Photoaging of  Hairless Mice Skin
%A Masaaki Sakura
%A Yoichi Chiba
%A Emi Kamiya
%A Ayako Furukawa
%A Noriko Kawamura
%A Masanao Niwa
%A Minoru Takeuchi
%A Yasushi Enokido
%A Masanori Hosokawa
%J Modern Research in Inflammation
%P 82-89
%@ 2169-9690
%D 2014
%I Scientific Research Publishing
%R 10.4236/mri.2014.33010
%X <p class=\"MsoNormal\" style=\"text-align:justify;\">
	<span lang=\"EN-US\" style=\"font-size:10pt;font-family:'}', serif;\"><span style=\"font-size:12px;font-family:Verdana;\">Skin photoaging is a
complex, multifactorial process resulting in functional and structural changes
of the skin, and different phenotypes from chronological skin aging are
well-recognized. Ultraviolet (UV)-irradiated hairless mice have been used as a
skin photoaging animal model. However, differences in morphology and gene
expression patterns between UV-induced and chronological skin changes in this mouse
model have not been fully elucidated. Here we investigated differences in
histopathology and cytokine expression between UV-irradiated and non-irradiated
aged hairless mice to clarify the factor(s) that differentiate photoaging from
chronological skin aging phenotypes. Eight-week-old HR-1 hairless mice were
divided into UV-irradiated (UV-irradiated mice) and non-irradiated (control
mice) groups. Irradiation was performed three times per week for 10 weeks. In
addition, 30-week-old HR-1 hairless mice were reared until 70 weeks of age
without UV irradiation (aged mice). Histopathologies revealed that the
flattening of dermal-epidermal junctions and epidermal thickening were observed
only in UV-irradiated mice. Decreases in fine elastic fibers just beneath the
epidermis, the thickening of elastic fibers in the reticular dermis, and the
accumulation of glycosaminoglycans were more prominent in UV-irradiated mice as
compared to non-irradiated aged mice. Quantitative PCR analyses revealed that
UV-irradiated mice showed an increase in the expression of IFN-</span><i><span style=\"font-size:12px;font-family:Verdana;\">¦Ã</span></i><span style=\"font-size:12px;font-family:Verdana;\">. In
contrast, aged mice exhibited proportional up-regulation of both
pro-inflammatory and anti-inflammatory cytokines. The IFN-</span><i><span style=\"font-size:12px;font-family:Verdana;\">¦Ã</span></i><span style=\"font-size:12px;font-family:Verdana;\">/IL-4 ratio,
an indicator for the balance of pro-inflammatory and anti-inflammatory
cytokines, was significantly higher in UV-irradiated mice as compared to
control and non-irradiated aged mice. An elevated IFN-</span><i><span style=\"font-size:12px;font-family:Verdana;\">¦Ã</span></i><span style=\"font-size:12px;font-family:Verdana;\">/IL-4 ratio was
also observed in aged senescence-accelerated mouse-prone 1 (SAMP1) mice, a
spontaneous skin photoaging model we recently reported. Thus, an imbalance
between pro-inflammatory and anti-inflammatory cytokines might be
%K Photoaged Skin
%K Chronologically-Aged Skin
%K Pro-Inflammatory Cytokines
%K Anti-Inflammatory  Cytokines
%K Hairless Mice
%U http://www.scirp.org/journal/PaperInformation.aspx?PaperID=48078