Dietary glucosylceramide enhances tight junction function in skin epidermis via induction of claudin-1.

Dietary glucosylceramide increased the expression of claudin-1 in UVB-irradiated mouse epidermis. Sphingosine and phytosphingosine, metabolites of glucosylceramide, increased trans-epithelial electrical resistance, and phytosphingosine increased claudin-1 mRNA expression in cultured keratinocytes. Our results indicate that the skin barrier improvement induced by dietary glucosylceramide might be due to enhancement of tight junction function, mediated by increased expression of claudin-1 induced by sphingoid metabolites.

Dietary immature Citrus unshiu alleviates UVB- induced photoaging by suppressing degradation of basement membrane in hairless mice.

Ultraviolet (UV) irradiation induces physiological and morphological skin damage, resulting in skin dryness, wrinkle formation, and loss of elasticity. The basement membrane (BM) has been shown to play crucial roles in binding epidermis to dermis tightly, regulating cell differentiation and proliferation, and signaling protein production. Dietary flavonoids have been revealed to improve the damage caused by UV exposure. Immature Citrus unshiu is known to contain high concentrations of flavonoids such as hesperidin and narirutin. In this study, the effects of immature Citrus unshiu powder (ICP) on photoaged skin were demonstrated using UVB irradiated hairless mice. Oral administration of ICP improved loss of skin hydration and increase of transepidermal water loss. The histological analyses of hairless mice dorsal skin revealed that oral administration of ICP improved UVB-induced overgrowth of epidermal cell, suppressed epidermal cell mortality and BM destruction. Therefore, the administration of ICP could improve photoaging by protecting the tissues around BM.

Increase in bone mineral density through oral administration of shark gelatin to ovariectomized rats.

OBJECTIVE: The incidence of bovine spongiform encephalopathy has resulted in marine collagen hydrolysate (low-molecular-weight gelatin) being sold as supplements and cosmetics in Japan. Shark skin collagen is one of the important sources of marine collagen. We examined the effect of shark skin gelatin in an osteoporosis model animal. METHODS: Shark skin gelatin was orally administered to ovariectomized rats with a low-protein diet. Bone mineral density of the right femur was measured. Collagen and glycosaminoglycan in the tibial end were extracted and analyzed by western blotting and cellulose acetate membrane electrophoresis, respectively. RESULTS: Administering collagen to the ovariectomized rats resulted in the bone mineral density of the femur epiphysis being higher than that in the sham-operated rats. The contents of type I collagen and glycosaminoglycan in the epiphysis were increased by administering shark skin gelatin. CONCLUSIONS: These results indicated that shark skin gelatin would be useful as a dietary supplement for treating osteoporosis.

Hyaluronic acid secretion by synoviocytes alters under cyclic compressive load in contracted collagen gels.

Knee osteoarthritis is a degenerative disease of diarthrodial joints. Biomechanical factors are considered as risk factors for the disease, the knee joint being normally subject to pressure. Some studies have examined the biomechanical environment of the knee joint in vitro. The aim of this study was to establish a culture model to mimic the knee joint environment. As a first step, synoviocytes induced contraction of three-dimensional collagen gels. Next, contracted collagen gels containing synoviocytes underwent cyclical compression ranging from 0 to 40 kPa at a frequency of 1.0 Hz for 1.5, 3, 6 and 12 h using the FX-4000C™ Flexercell(®) Compression Plus™ System. RNA in collagen gels was extracted immediately after compression and mRNA expression levels of HAS genes were analyzed by quantitative RT-PCR. Culture medium was collected 48 h after compression and analyzed by agarose gel electrophoresis and cellulose acetate electrophoresis. Synoviocytes in contracted collagen gels were stimulated by cyclic compressive load. Long-term compressive stimulation led to the production of higher molecular weight hyaluronic acid, whereas, short-term, compressive stimulation increased the total amount of hyaluronic acid. Furthermore, mRNA expression levels of both HAS-1 and HAS-2 were significantly higher than without compression. Taken together, using this gel culture system, synoviocytes synthesized higher molecular weight hyaluronic acid and produced large quantities of hyaluronic acid through up-regulation of HAS gene expression. Therefore, the contracted collagen gel model will be a useful in vitro three-dimensional model of the knee joint.

Structural changes in the glycosaminoglycan chain of rat skin decorin with growth.

Decorin controls collagen fibrilogenesis in skin, and its molecular weight changes in wound healing and with age. In this report, the quantitative and structural changes of decorin were investigated with growth in rat skin from the fetus to the young adult. A northern blot analysis showed that the highest level of skin decorin mRNA was at post partus 0.5 days; this level was about 3.7 times the level at embryo 16.5 days. The mRNA level in the rat skin decreased by 1/5 from post partus 0.5 days until 90 days of age. Western blotting showed that the amount of decorin increased with age in protein level. The molecule size of decorin at embryo 18.5 days was about 110 kDa, and that at post partus 90 days was about 70 kDa. There were no changes in molecular size of its core protein, so the reduction in the size of decorin was dependent on the size of the glycosaminoglycan (GAG) as shown by western blot analyses. Electron micrography of the rat skin with cupromeronic blue staining showed that the length of GAG at embryo 18.5 days was about 78.58 +/- 13.94 nm, and that at post partus 90 days was about 54.05 +/- 4.79 nm. The reduction in length of decorin GAG with age shrunk the distance between the collagen fibrils. We suggested that decorin changes the GAG length in order to control skin reconstruction in response to inflammation and injury.

Shark protein improves bone mineral density in ovariectomized rats and inhibits osteoclast differentiation.

OBJECTIVES: Fish proteins are potential sources of natural medicines and food additives. There are many studies being performed to develop underutilized fish proteins. Therefore, the aim of this study was to determine how shark protein functions as a dietary supplement for bone health. METHODS: Three groups of ovariectomized (OVX) rats were fed different diets containing 20% casein protein, 20% shark protein, or 20% cod protein for 4 wk. Bone mineral density of the right femur was measured by dual-energy x-ray absorptiometry and quantitative computed tomography. Furthermore, we prepared low-molecular-weight peptides from shark protein using protease for in vitro studies. Calcitriol was added to bone marrow cells and the receptor activator of the nuclear factor-κB ligand was added to RAW264 cells. After 7 d, the number of tartrate-resistant acid phosphatase-positive cells was counted. RESULTS: In the shark protein-fed group, bone mineral density of the femur epiphysis was higher than that of the casein protein-fed group. In particular, the shark protein-fed group showed an increase in bone mineral density, represented mainly by trabecular bone. Shark protein hydrolysates inhibited osteoclast formation in bone marrow cells and RAW264 cells. CONCLUSIONS: These results suggest that shark protein might suppress the bone loss caused by estrogen deficiency through the suppression of osteoclast formation.

Change in decorin during aging of rat placenta.

By immunohistochemistry, with or without chondroitinases, decorin was found to be distributed in the extracellular matrix of chorionic villi and amnia. The strength of staining intensified with increasing gestational age. Decorin was isolated from the placenta of 13- to 20-day-old pregnant rats and identified by Western blotting, using an antidecorin core protein antibody. The molecular weight of decorin is approximately 100 kDa, whereas the respective figures for the core protein treated with chondroitinase (chase) ABC and with chase B are approximately 40 kDa and 43 kDa. The difference in the molecular weight between the core protein with chase ABC and B suggests that the glycosaminoglycan (GAG)- base structure on the core protein was chondroitin sulfate (CS) without dermatan sulfate (DS). The decorin content and the proportion of CS to DS in GAG increased with age. We concluded that the age-related changes in the GAG chain may be related to specific functional properties and may have a crucial role in placental tissue organization.