Keratinocyte Cultures as Models for Dermatological Disease
John P. Sundberg in Handbook of Mouse Mutations with Skin and Hair Abnormalities, 2020
Other diseases also have been studied, using various cultured keratinocyte systems as models, and they include cutaneous infectious diseases [caused by viruses (such as herpes simplex, pox, and papillomaviruses), bacterial agents (including Streptococcus spp. and Staphylococcus spp.), or fungal organisms (such as Candida spp.)], genetic diseases [ichthyoses (such as epidermolytic hyperkeratosis, ichthyosis vulgaris, and nonbullous congenital ichthyosiform erythroderma), keratosis follicularis (Darier’s disease), familial benign pemphigus (Hailey-Hailey disease)], and various forms of acquired pemphigus, psoriasis, and other papulosquamous diseases, UV radiation and dioxin (2,3,7,8-tetrachlorodibenzo-p-dioxin, TCDD) damage/toxicity, and skin cancers (including basal cell and squamous cell carcinoma). This list identifies but a few of many dermatological diseases that have been or could be investigated using cultured keratinocytes.
Biology of the Hair and Skin
Randy Schueller, Perry Romanowski in Conditioning Agents for Hair and Skin, 2020
The skin develops at 30 to 40 days gestation and consists of two primary layers: the epidermis and dermis (8,9). The epidermis represents the external layer of skin and is composed mainly of keratinocytes, named for their primaiy proteinaceous component, known as keratin. The keratinocytes are held together by cellular attachments or desmosomes. The epidermis also contains melanocytes, which produce a pigment known as melanin, and specialized immune cells, known as Langerhans cells. It is divided into several distinct functional layers: the basal cell layer (stratum germinativum), from which all new cells are derived; the spinous layer.(stratum spinosum); the granular cell layer (stratum granulosum); and the horny cell layer (stratum corneum) (10). The stratum corneum is the outermost layer of the epidermis, comprised of 15 to 20 cell layers, functioning to protect the underlying tissues and nerves from damage. Products aimed at conditioning the skin must have significant impact on the stratum corneum.
Actions of Dopamine on the Skin and the Skeleton
Nira Ben-Jonathan in Dopamine, 2020
The epidermis has a 5- to100-μm thickness, depending upon its location, and is composed of stratified squamous epithelium devoid of blood or nerve supplies. Keratinocytes are the major cell type, constituting 95% of the epidermis, which also contains melanocytes. The deepest section of the epidermis, the stratum basale (basal layer or BL), is the reproductive layer of the epidermis. Its cells constantly divide and provide a continuous supply of new cells to the upper strata. This layer also contains neuroendocrine mechanoreceptors (Merkel cells). The proliferating keratinocytes are pushed upward to form the stratum spinosum (spinous layer or SL). The SL consists of about 10 rows of cells that fit closely together and are connected by desmosomes, or specialized structures for cell-to-cell adhesion. Also found in the SL are bone marrow-derived sentinel cells of the immune system called Langerhans’ cells, which are the antigen-presenting cells of the skin and play a role in immunological reactions such as allergic contact dermatitis. As they move upward toward the skin surface, keratinocytes gradually flatten and become part of the stratum granulosum, where the nondividing keratinocytes produce of a protein called keratinohyalin. The next layer, stratum lucidum, is present only in the thick skin of palms and soles.
Exposure to the anti-microbial chemical triclosan disrupts keratinocyte function and skin integrity in a model of reconstructed human epidermis
Published in Journal of Immunotoxicology, 2023
Rachel Baur, Michael Kashon, Ewa Lukomska, Lisa M. Weatherly, Hillary L. Shane, Stacey E. Anderson
Keratinocytes are key players in the structural integrity of the skin and they are involved in sensing and reacting to the environment (Hammad and Lambrecht 2015). Cytokine signaling is a key mechanism that keratinocytes use to interact with immune cells, both by producing cyto-kines and responding to cytokines via cytokine receptors (Hammad and Lambrecht 2015; Jiang et al. 2020). Certain cytokines that are produced by epithelial cells including keratinocytes, such as thymic stromal lymphopoietin (TSLP), IL-25, and IL-33, can communicate with immune cells and skew immune responses toward T-helper cell Type 2 (TH2) responses, leading to increased risk of sensitization (Hammad and Lambrecht 2015; Goleva et al. 2019). Dermal exposure to triclosan has been shown to increase levels of Tslp, as well as other signaling molecules such as S100 calcium-binding protein A8 (S100a8), IL-1β (Il1b), chemokine (C-X-C motif) ligand (Cxcl)1, and Cxcl2 in mouse skin (Anderson et al. 2020; Weatherly et al. 2020). Additionally, triclosan exposure on mouse skin has been shown to alter expression of filaggrin and keratin genes, demonstrating an impact on keratinocytes (Baur et al. 2021). Exposure to triclosan on human keratinocytes in vitro has been shown to alter metabolic pathways and increase pro-inflammatory cytokines (Liang et al. 2021). However, the impact of triclosan exposure on human keratinocyte response and the skin barrier is not well understood.
A comprehensive review on transethosomes as a novel vesicular approach for drug delivery through transdermal route
Published in Journal of Liposome Research, 2023
Minahal Munir, Muhammad Zaman, Muhammad Ahsan Waqar, Huma Hameed, Tehseen Riaz
The epidermis, which makes up the skin’s outer layer, is composed of keratinocytes. It further consists of non-viable and viable epidermal layers. Stratum corneum or horny layer is another name for the non-viable epidermal layer and it is the skin’s outermost layer. It is made up of tightly packed lipid bilayers that are found in the spaces in between corneocytes. It acts as a vital barrier to drug permeation into the skin and its absorption (CEVC 1996). The connective tissue matrix makes up the dermis layer and it is where drugs are absorbed. Subcutaneous adipose tissue makes up the third layer of skin called the hypodermis or subcutis layer. It serves as a shock absorber for nerve endings and blood vessels. It also serves as a nourishing and protecting covering (Godin and Touitou 2003).
Miconazole and terbinafine induced reactive oxygen species accumulation and topical toxicity in human keratinocytes
Published in Drug and Chemical Toxicology, 2022
P.-L. Lam, M.-M. Wong, L.-K. Hung, L.-H. Yung, J. C.-O. Tang, K.-H. Lam, P.-Y. Chung, W.-Y. Wong, Y.-W. Ho, R. S.-M. Wong, R. Gambari, C.-H. Chui
HaCaT cells were seeded at a concentration of approximately 1 × 105 cells/mL and counted manually using a haematocytometer under an inverted microscope. After 24 hours, the culture medium was changed and incubated with the antifungal drugs (miconazole and terbinafine) and doxorubicin at their IC50 values on HaCaT cells. DMSO at 1% was used as a vehicle control. After a further incubation of 24 hours, H2O2 at 100 µM was added as the positive reference. All the culture media were changed after 2 h and cells were incubated with 2′,7′-dichlorofluorescein diacetate (DCFH-DA, Molecular Probe) for a further of 30 min. Skin keratinocytes were washed and collected. Cells were subsequently lysed and total cellular protein was collected while debris was discarded. Protein content was determined by using the Bradford reagent. The relative level of ROS from each of 20 μg of total protein sample was determined by measuring its fluorescence units at 515 nm after an excitation at 485 nm using a microplate reader (Chui et al.2009). Experiments were performed in triplicate.