Development of Dry Skin in the NOA Mouse Under Individual Housing Conditions: A Potentially Useful Animal Model for Evaluating Moisturizing Effects

Lactobacillus plantarum L-137 upregulates hyaluronic acid production in epidermal cells and fibroblasts in mice

Heat-killed Lactobacillus plantarum L-137 (HK L-137), an immunobiotic lactic acid bacterium, has been reported to enhance IFN-γ production through induction of IL-12. In this study, we investigated the effects of HK L-137 on skin moisturizing and production of hyaluronic acid (HA), an extracellular matrix associated with the retention of skin moisture. Oral administration of HK L-137 suppressed the loss of water content in the stratum corneum in hairless mice. Treatment of primary epidermal cells with HK L-137 increased HA production. Supernatant from immune cells stimulated by HK L-137, which contained proinflammatory cytokines such as IL-12, TNF-α, and IFN-γ, upregulated HA production and hyaluronan synthase 2 (HAS2) messenger RNA expression by BALB/3T3 fibroblasts via activation of transcription factor nuclear factor κB (NFκB). Although treatment of the supernatant with anti-TNF-α antibody (Ab) alone did not inhibit the HA production, combination of anti-TNF-α Ab with anti-IFN-γ Ab significantly inhibited the HA production. Thus, HK L-137-induced IFN-γ plays a critical role in upregulated HA production in collaboration with TNF-α. HK L-137 may be useful for improvement of skin functions such as moisture retention by inducing HA production.

Sex differences regarding the amelioration of wrinkles due to skin dryness by the administration of tranexamic acid

Tranexamic acid (trans-4-aminomethylcyclohexanecarboxylic acid) exerts an amelioration effect on wrinkle formation due to skin dryness. We examined the sex differences in this effect. We administered tranexamic acid (750mg/kg/day) orally for 20 consecutive days to male and female Naruto Research Institute Otsuka Atrichia (NOA) mice, which naturally develop skin dryness. In the treated female mice, the amelioration effect on the wrinkle score, deterioration of transepidermal water loss (TEWL), capacitance, and decrease in the expression of collagen type I was stronger than in the male treated mice. Furthermore, the level of β-endorphin in the plasma and the expression of β-endorphin, μ-opioid receptor, and macrophages in the dorsal skin increased after the administration of tranexamic acid, and this increase was higher in female mice than in males. In addition, the macrophage production was increased by the administration of tranexamic acid in the ovary but did not change after administration in the testes. A histological examination revealed that these macrophages produce the β-endorphin, clarifying the source of the elevated levels. The amelioration effect in the female treated mice was decreased by the administration of clophosome (a macrophage inhibitor) to a degree that did not markedly differ from the effect observed in the male treated mice. These results suggest that the amelioration effect on wrinkles is stronger in female NOA mice than in males and that β-endorphin produced by macrophages plays an important role in this sex difference.

Search for Solutions: Animal Models of Disease

Disease researchers use animal models to study potential etiologies, pathophysiologies, and treatments. Responsive models must be predictable, emulating human conditions, and produce results that can be extrapolated and transposed. These models are often better than in vitro study or computer models, but still have limitations. Animal models can be difficult to maintain and are usually quite costly. Numerous methods are used to develop animal models including chemical exposure, genetic "knockout or knock in," or forward genetic modeling. Recently, more accurate animal models of Alzheimer's disease, osteoporosis, cancer, and mental illness have been developed. The strengths and limitations of each are discussed.

Comparative study of the state of water in various human tissues

We studied the dependence of water exchange in various human tissues (skin, Achilles tendon, various types of hyaline cartilage, muscle, and muscle fascia) on the content of collagen and proteoglycans. Carbohydrates of the connective tissue do not play the major role in tissue water exchange. Collagen fibers and proteoglycan aggregates probably retain the main part of bound and free water, respectively.

Increased susceptibility to Staphylococcus aureus colonization of the skin of the NOA mouse: a potentially useful animal model for evaluating antiseptic effects

Isolation of bacteria from wet skin lesions was attempted using Naruto Research Institute Otsuka Atrichia (NOA) mice, which develop such lesions spontaneously at a high rate. As a result, Staphylococcus aureus was demonstrated to have colonized the wet skin lesions at high density. In addition, the isolated S. aureus was found to be similar to the strain of S. aureus thought to colonize the eczematous lesions seen in humans with atopic dermatitis. Furthermore, a survey of the S. aureus colonization status of NOA mice with no wet skin lesions confirmed colonization at higher density than in HR-1 mice as control, indicating that the skin of the NOA mouse has the novel characteristic of increased susceptibility to S. aureus colonization. Thus, by using changes in S. aureus counts as an index, the NOA mouse can be expected to serve as a useful animal model for evaluating the effects of topical antiseptics. The antiseptic effects of an ointment and a lotion containing chlorhexidine gluconate were confirmed using this animal model.