Investigation of the interaction of keratinocytes and Candida species

Our skin provides immunological protection against several pathogens. Skin epithelial cells respond to microbial stimuli in various ways, such as through the production of antimicrobial peptides or secretion of cytokines, although phagocytosis of potentially evading microbes was also reported. Relatively little is known about how skin keratinocytes differentiate between the presence of pathogenic and commensal fungi. In this project, we aimed to investigate how human keratinocytes interact with different Candida species, as common colonizers of the skin. While C. albicans is a common cause of cutaneous candidiasis, C. parapsilosisis rarely associated with this disease.For the experimentshuman skin keratinocyte cell lines (HaCaT, HPV-KER)were applied andchallengedwith C. albicans (SC5314 and WO1 strains) and C. parapsilosis (GA1 and CLIB214 strains)strains.We aimedto determine the extent to which C. albicans and C. parapsilosis damage human keratinocytes, their attachment to host cells, the keratinocytes’ ability to internalize these fungi and to examinecytokine production in response to stimuli. Our results suggest that C. albicans causes significantly more damage to human keratinocytes than C. parapsilosis and the HPV-KER cell line was more susceptibleto the infection. In both HaCaT and HPV-KER cells, the production of IL-6, IL-8, and CCL5 increased primarilyafter C. albicans infection. Based on the adhesion studies, there was a low degree of association in case of C. parapsilosis GA1 and CLIB214 compared to C. albicans SC5314 and WO1.

Improvement of Cell Culture Methods for the Successful Generation of Human Keratinocyte Primary Cell Cultures Using EGF-Loaded Nanostructured Lipid Carriers

Human skin keratinocyte primary cultures can be established from skin biopsies with culture media containing epithelial growth factor (EGF). Although current methods are efficient, optimization is required to accelerate the procedure and obtain these cultures in less time. In the present study, we evaluated the effect of novel formulations based on EGF-loaded nanostructured lipid carriers (NLC). First, biosafety of NLC containing recombinant human EGF (NLC-rhEGF) was verified in immortalized skin keratinocytes and cornea epithelial cells, and in two epithelial cancer cell lines, by quantifying free DNA released to the culture medium. Then we established primary cell cultures of human skin keratinocytes with basal culture media (BM) and BM supplemented with NLC-rhEGF, liquid EGF (L-rhEGF), or NLC alone (NLC-blank). The results showed that cells isolated by enzymatic digestion and cultured with or without a feeder layer had a similar growth rate regardless of the medium used. However, the explant technique showed higher efficiency when NLC-rhEGF culture medium was used, compared to BM, L-rhEGF, or NLC-blank. Gene expression analysis showed that NLC-rhEGF was able to increase EGFR gene expression, along with that of other genes related to cytokeratins, cell–cell junctions, and keratinocyte maturation and differentiation. In summary, these results support the use of NLC-rhEGF to improve the efficiency of explant-based methods in the efficient generation of human keratinocyte primary cell cultures for tissue engineering use.

Protective Effects of Polyvinylpyrrolidone-Wrapped Fullerene Against Nitric Oxide/Peroxynitrite-Induced Cellular Injury in Human Skin Keratinocytes

Excess ultraviolet (UV) exposure accelerates skin inflammation, melanogenesis, wrinkle formation, photoaging, and carcinogenesis through oxidative stress and deoxyribonucleic acid damage. These deleterious effects to skin are closely associated with UV-induced reactive oxygen species (ROS) and reactive nitrogen species (RNS) produced via nitric oxide (NO·) generation. RNS are known to be responsible for various skin disorders, such as erythema, melanin production, reduced barrier function, and psoriasis. These skin disorders are major cosmetic problems; RNS control, in addition to ROS control, is important for maintaining healthy skin. In the present study, we investigated the cytoprotective effects of polyvinylpyrrolidone-entrapped fullerene (C60/PVP), a water-soluble ROS scavenger, against nitric oxide (NO·) and peroxynitrite (ONOO-)-induced human keratinocyte injuries. Protective effects of C60/PVP on NO·/ONOO--induced cellular damage and intracellular ONOO- generation were evaluated using a NO· donor S-nitroso-N-acetylpenicillamine (SNAP) in human skin epidermal HaCaT keratinocytes. Furthermore, the suppressive effect of C60/PVP on UVB-induced generation of intracellular ONOO- levels was also investigated. C60/PVP exerted suppressive effects on intracellular increases in NO·-induced ONOO- generation and subsequent cellular damage. Additionally, C60/PVP significantly decreased the UVB-induced generation of intracellular ONOO- levels. These findings suggest that C60/PVP could be useful as a cosmetics ingredient for prevention of skin injuries and/or dysfunction from NO·/ONOO--induced effects in human skin keratinocytes.