Mathematical-model-guided development of full-thickness epidermal equivalent.

Epidermal equivalents prepared with passaged keratinocytes are typically 10-20 μm thick, whereas intact human epidermis is up to 100 μm thick. Our established mathematical model of epidermal homeostasis predicted that the undulatory pattern of the papillary layer beneath the epidermis is a key determinant of epidermal thickness. Here, we tested this prediction by seeding human keratinocytes on polyester textiles with various fiber-structural patterns in culture dishes exposed to air, aiming to develop a more physiologically realistic epidermal model using passaged keratinocytes.

Abnormal Morphology of Blood Vessels in Erythematous Skin From Atopic Dermatitis Patients.

Previous studies suggest that altered peripheral blood circulation might be associated with erythema or inflammation in atopic dermatitis (AD) patients. However, the overall structure of blood vessels and capillaries in AD skin is poorly understood because most studies have involved light-microscopic observation of thin skin sections. In the present study, we compared the 3-dimensional structures of peripheral blood vessels of healthy subjects and AD patients in detail by means of 2-photon microscopy.

Coculture system of keratinocytes and dorsal-root-ganglion-derived cells for screening neurotrophic factors involved in guidance of neuronal axon growth in the skin.

The density of peripheral nerve fibres is increased in atopic dermatitis. Moreover, reduction in the fibres in a mouse model of atopic dermatitis reduces scratching behaviour. Thus, regulation of nerve fibre extension could be an effective strategy to reduce itching in pruritus dermatosis.

Low environmental humidity induces synthesis and release of cortisol in an epidermal organotypic culture system.

Dry environmental conditions induce a variety of skin pathologies and a recent report indicating that cortisol synthesis in epidermis was increased during wound healing led us to hypothesize that environmental dryness might induce increased cortisol secretion in epidermis. Therefore, we incubated a skin equivalent model under dry (relative humidity: less than 10%) and humid (relative humidity: approximately 100%) conditions for 48 hours and evaluated cortisol secretion and mRNA levels of cortisol-synthesizing enzyme (steroid 11β-hydroxylase, CYP11B1) and IL-1β. Cortisol secretion was increased threefold, and CYP11B1 and IL-1β mRNAs were increased 38-fold and sixfold, respectively, in the dry condition versus the humid condition.

External negative electric potential accelerates exocytosis of lamellar bodies in human skin ex vivo.

Exocytosis of lamellar bodies at the uppermost nucleated layer of the epidermis is a crucial process for epidermal permeability barrier homoeostasis. We have previously suggested that skin surface electric potential might be associated with barrier homoeostasis. Thus, we hypothesized that the potential might drive exocytosis of lamellar bodies.

How does epidermal pathology interact with mental state?

The hypothesis is presented that human emotional state is influenced by epidermal pathology via the release from epidermal keratinocytes of a wide variety of chemical mediators (including neurotransmitters) that act on the brain. It has long been recognized that epidermal keratinocytes play a key role in the function of the stratum corneum as an impermeable barrier, and that skin diseases such as atopic dermatitis and psoriasis, which cause itching, sleep disturbance and concern over appearance, are associated with depression and anxiety. On the other hand, epidermal keratinocytes are known to produce and release multiple cytokines and chemical mediators in response to barrier impairment or insult, such as environmental dryness or UV radiation.

In vitro formation of organized structure between keratinocytes and dorsal-root-ganglion cells.

We recently found that the morphology in a co-culture system of keratinocytes and dorsal-root ganglion-derived cells depended on the timing of seeding of the two cell types. In skin, epidermis is formed first, followed by construction of peripheral nerve structure. Therefore, we hypothesized that formation of peripheral nerve structure in the epidermis might be driven by interaction between keratinocytes and nerve cells.

Oxytocin is expressed in epidermal keratinocytes and released upon stimulation with adenosine 5'-[γ-thio]triphosphate in vitro.

Oxytocin is a neuropeptide produced primarily in the hypothalamus and is best known for its roles in parturition and lactation. It also influences behaviour, memory and mental state. Recent studies have suggested a variety of roles for oxytocin in peripheral tissues, including skin.

Ryanodine receptors are expressed in epidermal keratinocytes and associated with keratinocyte differentiation and epidermal permeability barrier homeostasis.

Ryanodine receptors (RyRs) have an important role as calcium channels in the regulation of intracellular calcium levels in the nervous system and muscle. In the present study, we investigated the expression of RyR in human epidermis. Immunohistochemical studies and reverse transcription-PCR indicated the expression of RyR type 1, 2, and 3 proteins in epidermal keratinocytes.

Morphological and functional differences in coculture system of keratinocytes and dorsal-root-ganglion-derived cells depending on time of seeding.

Previous study indicated that in a coculture system of keratinocytes and dorsal-root-ganglion-derived (DRG) cells, mechanical stimulation of keratinocytes induced ATP-mediated calcium propagation and excitation of DRG cells. Here, we examined two different coculture systems of keratinocytes and DRG cells. In one, we seeded keratinocytes first and then seeded DRG cells on the keratinocytes.

Phosphodiesterase inhibitors block the acceleration of skin permeability barrier repair by red light.

We previously demonstrated that exposure to red light (550-670 nm) accelerates epidermal permeability barrier recovery after barrier disruption. Furthermore, we showed that photosensitive proteins, originally found in retina, are also expressed in epidermis. In retina, transducin and phosphodiesterase 6 play key roles in signal transmission.

Topical application of TRPM8 agonists accelerates skin permeability barrier recovery and reduces epidermal proliferation induced by barrier insult: role of cold-sensitive TRP receptors in epidermal permeability barrier homoeostasis.

TRPA1 and TRPM8 receptors are activated at low temperature (A1: below 17 degrees C and M8: below 22 degrees C). Recently, we observed that low temperature (below 22 degrees C) induced elevation of intracellular calcium in keratinocytes. Moreover, we demonstrated that topical application of TRPA1 agonists accelerated the recovery of epidermal permeability barrier function after disruption.

Calcium ion propagation in cultured keratinocytes and other cells in skin in response to hydraulic pressure stimulation.

We have previously suggested that a variety of environmental factors might be first sensed by epidermal keratinocytes, which represent the frontier of the body. To further examine this idea, in the present study, we examined the intracellular calcium responses of cultured keratinocytes to external hydraulic pressure. First, we compared the responses of undifferentiated and differentiated keratinocytes with those of fibroblasts, vascular endothelial cells (VEC), and lymphatic endothelial cells.

Glycolic acid induces keratinocyte proliferation in a skin equivalent model via TRPV1 activation.

Background: Glycolic acid (GA) is the most commonly used alpha-hydroxy acid (AHA) for dermatologic applications, and is considered as a versatile superficial peeling agent for facial rejuvenation. Its therapeutic effect includes acceleration of epidermal turnover without apparent inflammation, and its action is pH-dependent. However, little is known about the molecular mechanism of GA-induced peeling.

Neuronal nitric oxide synthase in epidermis is involved in cutaneous circulatory response to mechanical stimulation.

The source of nitric oxide (NO) in the cutaneous circulation remains controversial. We hypothesized that epidermis might generate NO in response to mechanical stimulation. In hairless mouse (HR-1) skin organ culture, mechanical stimulation resulted in NO release, which declined within 30 minutes after cessation.

Mechanical-stimulation-evoked calcium waves in proliferating and differentiated human keratinocytes.

Calcium dynamics in the epidermis play a crucial role in barrier homeostasis and keratinocyte differentiation. We have recently suggested that the electro-physiological responses of the keratinocyte represent the frontier of the skin sensory system for environmental stimuli. In the present study, we have evaluated the responses of proliferating and differentiated human keratinocytes to mechanical stress by measuring the intracellular calcium level.

Expressions of rod and cone photoreceptor-like proteins in human epidermis.

Previous reports have suggested the existence of photoreceptors for visible radiation at the surface of the human body. Rhodopsin is a well-known photosensitive protein found in the rod cells of the retina and detects light/dark contrast. Cone opsins are also photosensitive receptors in the cone cells of the retina and detect colour.

Calcium ion gradients and dynamics in cultured skin slices of rat hindpaw in response to stimulation with ATP.

Ionotropic receptors, originally found in the brain, were recently also identified in epidermal keratinocytes. Moreover, concentration gradients and movement of calcium are crucial in epidermal homeostasis. Thus, imaging of calcium in the living epidermis is expected to provide insight into epidermal physiology and pathology.

Methods for identifying novel integrin ligands.

Integrins are cell adhesion receptors that have many important roles in organ development and tissue integrity, functioning to mediate interactions between cells and the ECM. The entire repertoire of integrins is vast, and the specific roles of each are determined by unique integrin-ligand interactions. These interactions allow for dynamic regulation of multiple processes.

Studies on integrins in the nervous system.

Integrins are of interest to neuroscientists because they and many of their ligands are widely expressed in the nervous system and have been shown to have diverse roles in neural development and function (Clegg et al., 2003; Li and Pleasure, 2005; Pinkstaff et al., 1998, 1999; Reichardt and Tomaselli, 1991; Schmid et al.