scholarly journals The genomic landscapes of individual melanocytes from human skin

2020 ◽  
Author(s):  
Jessica Tang ◽  
Eleanor Fewings ◽  
Darwin Chang ◽  
Hanlin Zeng ◽  
Shanshan Liu ◽  
...  
Keyword(s):  
Skin Cancer ◽  
Human Skin ◽  
Somatic Mutations ◽  
Phylogenetic Analyses ◽  
Normal Skin ◽  
Normal Human Skin ◽  
Exposed Skin ◽  
Mutation Burden ◽  
The Face ◽  
Normal Human

AbstractEvery cell in the human body has a unique set of somatic mutations, yet it remains difficult to comprehensively genotype an individual cell. Here, we developed solutions to overcome this obstacle in the context of normal human skin, thus offering the first glimpse into the genomic landscapes of individual melanocytes from human skin. We comprehensively genotyped 133 melanocytes from 19 sites across 6 donors. As expected, sun-shielded melanocytes had fewer mutations than sun-exposed melanocytes. However, within sun-exposed sites, melanocytes on chronically sun-exposed skin (e.g. the face) displayed a lower mutation burden than melanocytes on intermittently sun-exposed skin (e.g. the back). Melanocytes located adjacent to a skin cancer had higher mutation burdens than melanocytes from donors without skin cancer, implying that the mutation burden of normal skin can be harnessed to measure cumulative sun damage and skin cancer risk. Moreover, melanocytes from healthy skin commonly harbor pathogenic mutations, likely explaining the origins of the melanomas that arise in the absence of a pre-existing nevus. Phylogenetic analyses identified groups of related melanocytes, suggesting that melanocytes spread throughout skin as fields of clonally related cells, invisible to the naked eye. Overall, our study offers an unprecedented view into the genomic landscapes of individual melanocytes, revealing key insights into the causes and origins of melanoma.

Photosensitivity

2010 ◽  
pp. 4665-4671
Author(s):  
Jane McGregor
Keyword(s):  
Skin Cancer ◽  
Human Skin ◽  
Sun Exposure ◽  
Nonmelanoma Skin Cancer ◽  
Sunlight Exposure ◽  
Normal Human Skin ◽  
Normal Individuals ◽  
Normal Human ◽  
Fair Skin

Normal human skin is photosensitive in that it reddens following acute sunlight exposure and tans and thickens following chronic sunlight exposure. Skin cancer, particularly nonmelanoma skin cancer, is also a consequence of high cumulative sun exposure in genetically predisposed normal individuals (predominantly those with fair skin)....

117 Light or Dark Pigmentation of Engineered Skin Substitutes Containing Melanocytes Protects Against UV-Induced DNA Damage in Vivo

2020 ◽  
Vol 41 (Supplement_1) ◽  
pp. S78-S79
Author(s):  
Dorothy M Supp ◽  
Jennifer M Hahn ◽  
Christopher M Lloyd ◽  
Kelly A Combs ◽  
Viki B Swope ◽  
...  
Keyword(s):  
Dna Damage ◽  
Skin Cancer ◽  
Human Skin ◽  
Uv Irradiation ◽  
Wound Closure ◽  
Skin Substitutes ◽  
Normal Human Skin ◽  
Normal Human ◽  
Engineered Skin Substitutes

Abstract Introduction Engineered skin substitutes (ESS) were developed to meet the need for prompt wound closure in patients with large full thickness burns. ESS containing autologous fibroblasts and keratinocytes were shown to provide stable wound closure in burn patients, but are limited by hypopigmentation. DNA damage caused by ultraviolet (UV) radiation is a known risk factor for development of skin cancer. In normal human skin, epidermal melanocytes provide pigmentation, helping to shield skin from UV-induced DNA damage. The current study investigated inclusion of human melanocytes (hM) and their role in the response of ESS to UV light in vivo. Methods Primary cells were isolated from skin of healthy de-identified human donors with IRB approval. Three groups of ESS were prepared with fibroblasts and keratinocytes, +/- hM, and were grafted orthotopically to immunodeficient mice: ESS without hM; ESS with light skin-derived (Caucasian) hM (ESS+hML); and ESS with dark skin-derived (African American) hM (ESS+hMD). After 8 weeks in vivo, grafts were irradiated with 135 mJ/cm2 UV, and mice were euthanized after 2 or 24 hours; non-UV treated mice served as controls. Pigmentation and erythema were measured with a Mexameter. Melanocytes and cyclobutane pyrimidine dimers (CPDs) were quantified by immunostaining with anti-TYRP1 and anti-CPD antibodies, respectively, followed by image analysis (Nikon Elements). Statistical analyses (SigmaPlot) utilized t-test or one-way ANOVA; P< 0.05 was considered significant. Results At 8 weeks post-grafting, mean hM density in ESS+hML and ESS+hMD was not significantly different from normal human skin samples. Pigmentation (in Mexameter units) before UV irradiation was significantly different among groups (ESS+hMD > ESS+hML > ESS no hM). UV irradiation did not increase erythema in any group, but resulted in significantly increased pigmentation in ESS+hML and ESS+hMD at 2 hours, but not 24 hours, post-UV. CPDs, the most prevalent form of UV-induced DNA damage, were significantly elevated 24 hours post-UV in ESS without hM. DNA damage was significantly lower 24 hours post-UV in ESS+hML and ESS+hMD compared with ESS without hM. No differences in DNA damage were observed between ESS+hML and ESS+hMD. Conclusions Pigmentation of ESS+hML and ESS+hMD in vivo varied according to the skin phototype of the hM donor, with no difference in melanocyte density, which was similar to normal human skin. Inclusion of either light or dark hM decreased UV-induced DNA damage, suggesting that hM in ESS play a photoprotective role, as in normal human skin. Applicability of Research to Practice Protection against UV-induced DNA damage may reduce the risk of skin cancer in patients grafted with ESS containing melanocytes.

scholarly journals IMMUNOCHEMICAL STUDIES OF ANTITOXIN PRODUCED IN NORMAL AND ALLERGIC INDIVIDUALS HYPERIMMUNIZED WITH DIPHTHERIA TOXOID

1952 ◽  
Vol 95 (4) ◽  
pp. 375-392 ◽  
Author(s):  
William J. Kuhns ◽  
A. M. Pappenheimer
Keyword(s):  
Human Skin ◽  
Guinea Pigs ◽  
Anaphylactic Shock ◽  
High Titer ◽  
Normal Skin ◽  
The Other ◽  
Normal Human Skin ◽  
Shock Heating ◽  
Diphtheria Antitoxin ◽  
Normal Human

1. The immunological properties of two contrasting types of human antisera, each containing a high titer of diphtheria antitoxin, have been investigated. 2. Sera which contain only non-precipitating antitoxin exhibit most of the properties of atopic reagin-containing sera. This type of antitoxin is capable of sensitizing normal human skin to toxin or toxoid and remains for many weeks in the injected area. It exhibits no Danysz effect, does not fix complement unless very large amounts of serum are used, and can be specifically coprecipitated by addition of precipitating antitoxin and toxin. On the other hand, it is capable of sensitizing guinea pigs to fatal anaphylactic shock. Heating at 56°C. for 4 hours destroys the skin-sensitizing properties and results in almost quantitative conversion to a modified antitoxin which is capable of blocking the wheal and erythema reaction caused by injection of toxoid into sensitized skin. Heating at 56°C. does not result in an appreciable loss of neutralizing power as judged by tests in rabbit and human skin. The anaphylactogenic property of nonprecipitating antibody is likewise unaffected by heat at 56°C. 3. Precipitating antitoxin is incapable of sensitizing normal skin to toxin or toxoid and disappears rapidly from the injected sites. It fixes complement to high titer and sensitizes guinea pigs to fatal anaphylactic shock. It was possible to demonstrate inhibition of the wheal and erythema reaction in sensitized skin by injecting certain mixtures of precipitating antitoxin and toxoid. 4. The two antitoxic sera studied in greatest detail represented extreme cases. Many persons immunized with toxoid developed both precipitating and nonprecipitating antitoxin simultaneously.

scholarly journals Ultra-deep sequencing differentiates patterns of skin clonal mutations associated with sun-exposure status and skin cancer burden

2020 ◽  
Author(s):  
Lei Wei ◽  
Sean R. Christensen ◽  
Megan Fitzgerald ◽  
James Graham ◽  
Nicholas Hutson ◽  
...  
Keyword(s):  
Skin Cancer ◽  
Cancer Risk ◽  
Deep Sequencing ◽  
Normal Skin ◽  
Uv Exposure ◽  
Uv Damage ◽  
Clinically Normal ◽  
Exposed Skin ◽  
Mutation Burden ◽  
Genomic Regions

AbstractNon-melanoma skin cancer is the most common human malignancy and is primarily caused by exposure to ultraviolet (UV) radiation. The earliest detectable precursor of UV-mediated skin cancer is the growth of cell groups harboring clonal mutation (CM) in clinically normal appearing skin. Systematic evaluation of CMs is crucial to understand early photo-carcinogenesis. Previous studies confirmed the presence of CMs in sun-exposed skin. However, the relationship between UV-exposure and the accumulation of CMs, and the correlation of CMs with skin cancer risk remain poorly understood. To elucidate the exact molecular and clinical effects of long-term UV-exposure on skin, we performed targeted ultra-deep sequencing in 450 individual-matched sun-exposed (SE) and non-sun-exposed (NE) epidermal punch biopsies obtained from clinically normal skin from 13 donors. A total of 638 CMs were identified, including 298 UV-signature mutations (USMs). The numbers of USMs per sample were three times higher in the SE samples and were associated with significantly higher variant allele frequencies (VAFs), compared with the NE samples. We identified genomic regions in TP53, NOTCH1 and GRM3 where mutation burden was significantly associated with UV-exposure. Six mutations were almost exclusively present in SE epidermis and accounted for 42% of the overall difference between SE and NE mutation burden. We defined Cumulative Relative Clonal Area (CRCA), a single metric of UV-damage calculated by the overall relative percentage of the sampled skin area affected by CMs. The CRCA was dramatically elevated by a median of 11.2 fold in SE compared to NE samples. In an extended cohort of SE normal skin samples from patients with a high- or low-burden of cutaneous squamous cell carcinoma (cSCC), the SE samples in high-cSCC patients contained significantly more USMs than SE samples in low-cSCC patients, with the difference mostly conferred by mutations from low-frequency clones (defined by VAF≤1%) but not expanded clones (VAF>1%). Our studies of differential mutational features in normal skin between paired SE/NE body sites and high/low-cSCC patients provide novel insights into the carcinogenic effect of UV exposure, and indicate that CMs might be used to develop novel biomarkers for predicting cancer risk.Significance statementIn UV radiation exposed skin, mutations fuel clonal cell growth. We established a sequencing-based method to objectively assess the mutational differences between sun-exposed (SE) and non-sun-exposed (NE) areas of normal human skin. Striking differences, in both the numbers of mutations and variant allele frequencies, were found between SE and NE areas. Furthermore, we identified specific genomic regions where mutation burden is significantly associated with UV-exposure status. These findings revealed previously unknown mutational patterns associated with UV-exposure, providing important insights into UV radiation’s early carcinogenic effects. Additionally, in an extended cohort, we identified preliminary association between normal skin mutation burden and cancer risk. These findings pave the road for future development of quantitative measurement of subclinical UV damage and skin cancer risk.

scholarly journals High burden and pervasive positive selection of somatic mutations in normal human skin

Science ◽  
2015 ◽  
Vol 348 (6237) ◽  
pp. 880-886 ◽  
Author(s):  
I. Martincorena ◽  
A. Roshan ◽  
M. Gerstung ◽  
P. Ellis ◽  
P. Van Loo ◽  
...  
Keyword(s):  
Positive Selection ◽  
Human Skin ◽  
Somatic Mutations ◽  
Normal Human Skin ◽  
High Burden ◽  
Normal Human ◽  
Selection Of
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