Ryoko Iizuka

Monocytic differentiation modulates apoptotic response to cytotoxic anti-Fas antibody and tumor necrosis factor alpha in human monoblast U937 cells.

Interferon‐γ (IFN‐γ), vitamin D3 (VD), and retinoic acid (RA) induce differentiation of human monoblastic leukemia U937 cells to macrophage‐like cells with potential superoxide anion‐generating activity upon further stimulation. Here we report that U93 7 cells thus differentiated show various responses to apoptotic induction with a cytotoxic anti‐Fas antibody and tumor necrosis factor (TNF). VD‐or RA‐treated U937 cells acquired resistance against Fas‐ or TNF receptor (TNFR)‐mediated apoptosis, whereas apoptotic cell death was accelerated in IFN‐γ‐treated cells. By flow cytometric analyses, no decrease in expression of surface Fas antigen or p55 TNFR was observed in differentiated U937 cells. Cell surface expression of CD11b was seen only when differentiation was induced with VD or RA but not with IFN‐γ. The growth of VD‐ or RA‐treated cells was retarded but IFN‐γ‐treated cells were prolific. These findings suggest that the differentiation state differs with the inducer and that the cellular response to apoptotic induction is closely related to the state including the cell cycle. J. Leukoc. Biol. 60: 778–783; 1996.

Genistein and Daidzein Stimulate Hyaluronic Acid Production in Transformed Human Keratinocyte Culture and Hairless Mouse Skin

We examined the effects of the soy isoflavones genistein (Gen) and daidzein (Dai) on the production of hyaluronic acid (HA) in a transformed human keratinocyte culture and in hairless mouse skin following topical application for 2 weeks. Gen and Dai, but not the glycosides thereof, significantly enhanced the production of HA in vitro and in vivo. Histochemistry using an HA-binding protein revealed that topical Gen and estradiol raised both the density and intensity of HA staining, which was abundant in the murine dermis. It is suggested that Gen and Dai are not released from their respective glycosides in culture or murine skin. Moreover, topical Gen and Dai may prevent and improve the cutaneous alterations caused by the loss of HA in skin.

Streptococcus thermophilus produces exopolysaccharides including hyaluronic acid

Hyaluronic acid (HA) is an important material for medical, cosmetic and food applications. HA is obtained commercially from rooster combs and the fermentation of streptococci. However, the safety problems such as hyaluronidase or exotoxin contamination remain controversial. To reduce the risk of hyaluronidase or exotoxin contamination, we attempted to isolate strains of Streptococcus thermophilus with high productivity of useful exopolysaccharides (EPSs) including HA from traditional dairy food products. Forty-six S. thermophilus strains were isolated from dairy food products, and examined of their HA production using a HA binding protein method. According to the results, six S. thermophilus strains produced EPSs including HA. S. thermophilus YIT 2084 had a markedly high HA productivity (approximately 8 mg/l). We focused on the high-molecular-mass fraction of EPS (2000 kDa) from S. thermophilus YIT 2084. By using high-performance liquid chromatography, it was found that a high-molecular-mass fraction of EPS included N-acetylglucosamine (54.4%) and glucuronic acid (45.6%), which are components of HA. Furthermore, 13C-nuclear magnetic resonance spectroscopy showed that the spectra of the high-molecular-mass fraction corresponded well to those of commercial HA. Here, we described for the first time that S. thermophilus, which is a generally recognized safe bacterium, produces HA. The novel HA-producing bacterium S thermophilus YIT 2084 has great potential for applications in the medical, cosmetic and food fields, although its culture conditions remain to be improved.

Bifidobacterium-Fermented Soy Milk Extract Stimulates Hyaluronic Acid Production in Human Skin Cells and Hairless Mouse Skin

We examined the effects of Bifidobacterium-fermented (BE) and nonfermented (SME) soy milk extracts on the production of hyaluronic acid (HA) in vitro and in vivo. BE, but not SME, significantly enhanced the production of HA in monolayer and organotypic cultures of human keratinocytes, in cultures of human skin fibroblasts, and in hairless mouse skin following topical application for 2 weeks. In the organotypic cultures formed by a similar structure to human epidermis, BE also extended the distribution of HA. Genistein and daidzein, known to stimulate HA production, were detected in BE at a concentration of 0.18 and 0.07 mM, respectively, but not in SME. Therefore, BE has the potential to enhance HA production in the epidermis and dermis, mainly due to genistein released from its glycoside during fermentation. BE is expected to prevent the age-dependent loss of cutaneous HA.

Consecutive Intake of Fermented Milk Containing Bifidobacterium breve Strain Yakult and Galacto-oligosaccharides Benefits Skin Condition in Healthy Adult Women

A double-blind, placebo-controlled, randomized trial was conducted to investigate the beneficial effect of probiotic and prebiotic fermented milk on the skin of healthy adult women. Forty healthy Japanese adult female volunteers with healthy skin randomly received either a bottle of probiotic and prebiotic fermented milk containing Bifidobacterium breve strain Yakult and galacto-oligosaccharides (GOS) (active group) or a non-fermented placebo milk containing neither probiotics nor GOS (placebo group) daily for 4 weeks. Before and after intake, hydration levels and cathepsin L-like activity in the stratum corneum and phenol levels in the serum and urine were determined. After intake, the hydration level of the stratum corneum decreased significantly in only the placebo group and was significantly lower than in the active group (p=0.031). Cathepsin L-like activity, an indicator of keratinocyte differentiation, was significantly increased in the active group (p=0.027). Serum and urine phenol levels decreased significantly in the active group (p=0.014, p=0.002, respectively), and serum phenol levels were significantly lower in the active group compared with the placebo group (p=0.006). The consecutive intake of probiotic and prebiotic fermented milk can benefit skin condition without dryness and decrease the levels of phenol production by gut bacteria in healthy adult women.

Phenols produced by gut bacteria affect the skin in hairless mice

Objective: Phenol and p-cresol are metabolites of aromatic amino acid produced by gut bacteria, and are assumed to cause undesirable effects in the body. We aimed to understand how phenol and p-cresol affect the skin of hairless mice. Materials and methods: First, we compared the skin condition of hairless mice fed the basal diet and the skin condition of mice fed the tyrosine-enriched diet. In the next experiment, we administered either phenol or p-cresol intraperitoneally to mice fed the basal diet. Eventually, we isolated Morganella morganii, which is able to produce phenol, from the feces of mice fed the tyrosine-enriched diet, and Escherichia coli, which is not able to produce phenol, from the feces of mice fed the basal diet, and performed a gnotobiotic experiment. Results: In mice fed the tyrosine-enriched diet, phenol and p-cresol levels increased in cecal contents, serum, and flank skin, and a yellowish dullness, reflected by the color exam meters b* value, was exhibited by the skin. The b* value of phenol-administered mice was higher than that of saline- or p-cresol-administered mice. Furthermore, the size of the corneocytes of phenol-administered mice was significantly smaller than that of the saline- or p-cresol-administered mice. The M. morganii gnotobiotic mice exhibited a higher b* value and smaller corneocytes than the E. coli gnotobiotic mice. Conclusions: These results suggest that phenols produced by gut bacteria affect the skin in hairless mice.

Gut bacteria producing phenols disturb keratinocyte differentiation in human skin

Abstract Objective: Our previous study suggested that phenols (phenol and p-cresol) produced by gut bacteria affect the skin in hairless mice. In the present study we aimed to determine if the same phenomenon is applicable to humans. Methods: First, we analyzed the correlation between serum phenol levels and corneocyte size in 50 healthy female volunteers. Second, we administered a prebiotic beverage (containing galacto-oligosaccharides and polydextrose) to 19 healthy female volunteers and examined the correlations among fluctuation of phenol levels, corneocyte size, and cathepsin L-like activity. Finally, we performed an in vitro experiment using monolayer-cultured human keratinocytes to determine whether phenols physiologically affected keratinocyte differentiation. Results: In 50 healthy female volunteers, serum phenol levels showed a significant inverse correlation with skin corneocyte size. When a prebiotic beverage was administered for 3 weeks to 19 healthy female volunteers, p-cresol levels decreased significantly, and significant increases in corneocyte size and cathepsin L-like protease activity were seen. On in vitro examination, monolayer-cultured human keratinocytes subjected to 20 nmol/ml phenol or p-cresol failed to express K10 protein (a molecular marker for normal keratinocyte differentiation) under physiological conditions. Conclusions: These results suggest that phenols produced by gut bacteria adversely affect keratinocyte differentiation in female human skin. Furthermore, these results indicate that serum phenol levels are appropriate biomarkers of keratinocyte differentiation disturbances caused by an undesirable intestinal environment in humans.