Heat-mediated reduction of apoptosis in UVB-damaged keratinocytes in vitro and in human skin ex vivo

Relationship between climate change and skin cancer and implications for prevention and management: a scoping review

OBJECTIVES

This study aimed to explore the published research on the relationship between climate change and skin cancer and the implications for prevention, management and further research.

STUDY DESIGN

Scoping review.

METHODS

This scoping review following JBI methodology reviewed English articles identified in searches of MEDLINE, Embase, CINAHL, Web of Science and Scopus on 14 April 2023. The screening of articles was completed by two independent reviewers. Data were extracted by a single reviewer and checked by another. A causal pathway diagram was iteratively developed throughout the review and was used to categorise the findings.

RESULTS

The search identified 1376 papers, of which 45 were included in the final review. Nine papers reported primary research, and 36 papers were reviews, perspectives, commentaries, editorials, or essays. The papers examined climate change influencing behaviours related to ultraviolet exposure (30 papers), ambient temperature (21 papers) and air pollution (five papers) as possible risk factors; occupational, rural, and contextual factors affecting skin cancer (11 papers); and prevention and access to health care in the context of climate change (seven papers). Most papers were published in journals in subject areas other than health.

CONCLUSIONS

This review identified ultraviolet radiation, occupation, rising temperature, individual behaviour and air pollution as possible influences on skin cancer rates. Furthermore, it highlights the complexity and uncertainties in the relationship between climate change and skin cancer and the need for further research on this relationship, including primary epidemiological research and reviews that follow recognised review guidelines and include assessment of health services and social determinants in the causal pathways of this relationship.

Impact of climate change on non-communicable diseases caused by altered UV radiation

Background

UV radiation can cause serious skin and eye diseases, especially cancers. UV-related skin cancer incidences have been increasing for decades. The determining factor for this development is the individual UV exposure. Climate change-induced changes in atmospheric factors can influence individual UV exposure.

Methods

On the basis of a topic-specific literature research, a review paper was prepared and supplemented by as yet unpublished results of the authors' own studies. The need for scientific research and development is formulated as well as primary prevention recommendations.

Results

Climate change alters the factors influencing UV irradiance and annual UV dose in Germany. First evaluations of satellite data for Germany show an increase in mean peak UV irradiance and annual UV dose for the last decade compared to the last three decades.

Conclusions

The climate change-related influences on individual UV exposure and the associated individual disease incidence cannot yet be reliably predicted due to considerable uncertainties. However, the current UV-related burden of disease already requires primary preventive measures to prevent UV-related diseases.

Heat and outpatient visits of skin diseases – A multisite analysis in China, 2014–2018

Background

Many studies have shown that various kinds of diseases were associated with the variation of ambient temperature. However, there’s only a scrap of evidence paying attention to the link between temperature and skin diseases, and no relevant national research was performed in China.

Objective

This study aimed to quantify the effect of heat on skin diseases and identify the vulnerable populations and areas in China.

Methods

Daily meteorological data, air pollutant data and outpatient data were collected from in 18 sites of China during 2014–2018. A time-series study with distributed lag nonlinear model and multivariate meta-analysis was applied to analyze the site-specific and pooled associations between daily mean temperature and daily outpatient visits of skin diseases by using the data of warm season (from June to September). Stratified analysis by age, sex and climate zones and subtypes of skin diseases were also conducted.

Results

We found a positive linear relationship between the ambient temperature and risk of skin diseases, with a 1.25% (95%CI: 0.34%, 2.16%) increase of risk of outpatient visits for each 1 °C increase in daily mean temperature during the warm season. In general, groups aged 18–44 years, males and people living in temperate climate regions were more susceptible to high temperature. Immune dysfunction including dermatitis and eczema were heat-sensitive skin diseases.

Conclusions

Our findings suggested that people should take notice of heat-related skin diseases and also provided some references about related health burden for strategy-makers. Targeted measures for vulnerable populations need to be taken to reduce disease burden, including monitoring and early warning systems, and sun-protection measures.

Activation of the JNKs/ATM-p53 axis is indispensable for the cytoprotection of dermal fibroblasts exposed to UVB radiation

Although UVB radiation is mainly absorbed by the epidermis, ~5-10% of its photons reach and affect the upper part of the dermis. Physiologically relevant UVB doses, able to provoke erythema, induce apoptosis in human dermal fibroblasts in vitro, as well as in the dermis of SKH-1 mice. Given the sparse and even contradictory existing information on the effect of UVB radiation on dermal fibroblasts' viability, aim of this work was to unravel the crucial signaling pathways regulating the survival of UVB-treated human dermal fibroblasts. We found that UVB radiation immediately stimulates the phosphorylation of MAPK family members, as well as Akt, and is genotoxic leading to the delayed ATM-p53 axis activation. Akt phosphorylation after UVB radiation is EGFR-mediated and EGFR inhibition leads to a further decrease of viability, while the Akt activator SC79 rescues fibroblasts to an extent by a mechanism involving Nrf2 activation. The known Nrf2 activator sulforaphane also exerts a partial protective effect, although by acting in a distinct mechanism from SC79. On the other hand, inhibition of JNKs or of the ATM-p53 axis leads to a complete loss of viability after UVB irradiation. Interestingly, JNKs activation is necessary for p53 phosphorylation, while the ATM-p53 pathway is required for the long-term activation of JNKs and Akt, reassuring the protection from UVB. Although UVB radiation results in intense and prolonged increase of intracellular ROS levels, classical anti-oxidants, such as Trolox, are unable to affect Akt, JNKs, or p53 phosphorylation and to reverse the loss of fibroblasts' viability. Collectively, here we provide evidence that the main viability-regulating UVB-triggered biochemical pathways act synergistically towards the protection of human dermal fibroblasts, with EGFR/Akt and Nrf2 serving as auxiliary anti-apoptotic machineries, while JNKs/ATM-p53 activation and interplay being overriding and indispensable for the perpetuation of cellular defense and the maintenance of cell viability.

Astaxanthin Protects Ultraviolet B-Induced Oxidative Stress and Apoptosis in Human Keratinocytes via Intrinsic Apoptotic Pathway

Background

Ultraviolet radiation causes skin damage due to increased production of reactive oxygen species (ROS) and inflammatory intermediates and direct attack of DNA of skin cells. Astaxanthin is a reddish pigment that belongs to a group of chemicals called carotenoids and has protective effects as an antioxidant.

Objective

To determine the beneficial effects of astaxanthin on damaged human skin after exposure to ultraviolet radiation.

Methods

Normal human epidermal keratinocytes (NHEKs) were pre-treated with astaxanthin for 24 hours and exposed to ultraviolet B (UVB) irradiation. After 24 hours, the Cell Counting Kit-8 (CCK-8) assay measured cell viability, ROS assay and flow cytometry analysis assessed apoptosis, and western blotting was performed to determine expression of apoptosis-related proteins.

Results

Astaxanthin significantly inhibited UVB-induced NHEKs cytotoxicity. Pretreatment of NHEKs with astaxanthin reduced UVB-induced ROS production. Astaxanthin caused significant inhibition of UVB-induced apoptosis, as evidenced by flow cytometry analysis and western blotting.

Conclusion

These results suggest that astaxanthine has a beneficial effect of reducing damage caused by UVB by effectively inhibiting cell death and reducing ROS production in keratinocytes.

The Modulatory Influence of Plant-Derived Compounds on Human Keratinocyte Function

The plant kingdom is a rich source of secondary metabolites with numerous properties, including the potential to modify keratinocyte biology. Keratinocytes are important epithelial cells that play a protective role against various chemical, physical and biological stimuli, and participate in reactive oxygen scavenging and inflammation and wound healing processes. The epidermal cell response may be modulated by phytochemicals via changes in signal transduction pathways. Plant extracts and single secondary compounds can possess a high antioxidant capacity and may suppress reactive oxygen species release, inhibit pro-apoptotic proteins and apoptosis and activate antioxidant enzymes in keratinocytes. Moreover, selected plant extracts and single compounds also exhibit anti-inflammatory properties and exposure may result in limited production of adhesion molecules, pro-inflammatory cytokines and chemokines in keratinocytes. In addition, plant extracts and single compounds may promote keratinocyte motility and proliferation via the regulation of growth factor production and enhance wound healing. While such plant compounds may modulate keratinocyte functions, further in vitro and in vivo studies are needed on their mechanisms of action, and more specific toxicity and clinical studies are needed to ensure their effectiveness and safety for use on human skin.

Major climate change-induced risks to human health in South Africa

There are many climatic changes facing South Africa which already have, or are projected to have, a detrimental impact on human health. Here the risks to health due to several alterations in the climate of South Africa are considered in turn. These include an increase in ambient temperature, causing, for example, a significant rise in morbidity and mortality; heavy rainfall leading to changes in the prevalence and occurrence of vector-borne diseases; drought-associated malnutrition; and exposure to dust storms and air pollution leading to the potential exacerbation of respiratory diseases. Existing initiatives and strategies to prevent or reduce these adverse health impacts are outlined, together with suggestions of what might be required in the future to safeguard the health of the nation. Potential roles for the health and non-health sectors as well as preparedness and capacity development with respect to climate change and health adaptation are considered.

The influence of climate change on skin cancer incidence - A review of the evidence

BACKGROUND

Climate change is broadly affecting human health, with grave concern that continued warming of the earth's atmosphere will result is serious harm. Since the mid-20th century, skin cancer incidence rates have risen at an alarming rate worldwide.

OBJECTIVE

This review examines the relationship between climate change and cutaneous carcinogenesis.

METHODS

A literature review used the National Institutes of Health databases (PubMed and Medline), the Surveillance, Epidemiology, and End Results and International Agency for Research on Cancer registries, and published reports by federal and international agencies and consortia, including the Australian Institute of Health and Welfare, Climate and Clean Air Coalition, U.S. Environmental Protection Agency, Intergovernmental Panel on Climate Change, National Aeronautics and Space Administration, National Oceanic and Atmospheric Administration, United Nations Environment Programme, World Health Organization, and World Meteorological Organization.

RESULTS

Skin cancer risk is determined by multiple factors, with exposure to ultraviolet radiation being the most important. Strong circumstantial evidence supports the hypothesis that factors related to climate change, including stratospheric ozone depletion, global warming, and ambient air pollution, have likely contributed to the increasing incidence of cutaneous malignancy globally and will continue to impose a negative on influence skin cancer incidence for many decades to come.

CONCLUSION

Because much of the data are based on animal studies and computer simulations, establishing a direct and definitive link remains challenging. More epidemiologic studies are needed to prove causality in skin cancer, but the evidence for overall harm to human health as a direct result of climate change is clear. Global action to mitigate these negative impacts to humans and the environment is imperative.

Environmental changes and their impact on human behaviour - Case study of the incidence of skin cancer

Climatological research over the past two decades makes it clear that the Earth's climate will change. Climate change has many, mostly adverse, effects on the human health. Environmental anthropogenic changes represent significant health risks including factors that may increase probability and seriousness of skin cancer diseases. There are many scientific studies on skin cancer but only a few of them are focused on environment changes and their influence on the behaviour of humans, which may lead to skin cancer. The goal of the research was to analyse environment changes in the city of Brno (Czech Republic) and their influence on the behaviour of people and some skin diseases. A research hypothesis was set up that total increase in the incidence of skin diseases would be monitored. 1757 patients aged 25-65 years participated in the research. The analysis was performed based on measured (mean annual temperatures, average monthly temperatures, ultraviolet index values, and numbers of sunny days and sunny hours) data in 2011-2019. In order to monitor the trend, temperature data from 1961 to 2019 were evaluated too. The analysed data indicate that the trend of average monthly and annual temperatures observed was increasing in recent years. Moreover, based on data obtained from the analysed doctor's office it was found out that the incidence of skin diseases increased in the studied period. The main reasons to increase include excessive exposure to sun, extended average age of the population, ozone layer depletion, climatic and weather changes, increased migration and behaviour of people.

Influence of the Exposome on Skin Cancer

Skin cancer is the most frequent type of cancer in humans. While exposure to solar radiation is the most widely known and relevant causal factor, the different degrees of individual risk have not been fully elucidated. Epidemiological studies show how the risk of skin cancer is affected by other types of radiation (eg, ionizing radiation), pesticides, particulate matter in air pollution, toxins (eg, arsenic) in water and some foods. Some living entities, such as polyomavirus and human papillomavirus, can also cause specific types of cancer. Lastly, lifestyle factors such as stress, sleep, and exercise may play a role, although only a few studies shed light on these factors. The abovementioned factors make up the exposome of skin cancer, that is, the set of environmental exposures that, together with the genome and microbiome, determine the onset of disease.

The acute effects of ultraviolet radiation exposure on solar dermatitis in Shanghai, China

Ultraviolet radiation (UVR) has long been considered associated with solar dermatitis, but the associations have not been well quantified. To depict the full-range exposure-response association between daily UVR exposures and daily outpatient visits of solar dermatitis. We collected the daily number of outpatient visits of solar dermatitis and monitored hourly ground data of UVR (the sum of A- and B-band) from 1 January 2013 to 31 December 2017 in Shanghai, China. The data were analyzed using the time-series approach, in which overdispersed generalized additive model was used and time trends and weather conditions were controlled for. During the study period, we recorded a total of 15,051 outpatient visits of solar dermatitis. There was a consistently increasing risk of solar dermatitis associated with stronger UVR without a discernible threshold. The effects occurred on the present day, increased to the largest at lag 1 or 2 days, and attenuated to the null at lag 5 days or more. A unit (w/m²) increase in daily maximum-hour UVR was associated with 1.70% (95%CI: 1.19%, 2.20%) increase of outpatient visits of solar dermatitis. Stronger effects occurred among the young people, females, and in the warm season. The risks of solar dermatitis due to UVR exposure would be overestimated if ambient temperature was not adjusted. This study provides quantitative epidemiological estimates for the positive associations between short-term exposure to UVR and increased risks of solar dermatitis. The associations were more prominent among young people, females, and in warm seasons.

Balance between Health Risks and Benefits for Outdoor Workers Exposed to Solar Radiation: An Overview on the Role of Near Infrared Radiation Alone and in Combination with Other Solar Spectral Bands

Near infrared or infrared A (IRA) accounts for over 40% of the solar spectrum (SS) and is able to reach subcutaneous tissue as well as the retina. Outdoor workers are occupationally exposed to solar radiation (SR), but the level of exposure may differ widely depending on the job performed, time spent outdoors, latitude, altitude, season, personal protection, etc. Until now, risk assessment and management for outdoor workers has focused on the prevention of both acute and long-term effects on the eye and the skin due to solar ultraviolet radiation (UVR) with little consideration of the other components of the SS (a possible exception is represented by visible radiation with reference to the eye). A growing body of evidence coming from in vitro studies indicates that IRA is involved in cellular reactive oxygen species (ROS) production and may interfere with the respiratory chain in the mitochondria. Moreover, it can modulate gene expression and some metabolic pathways. The biological action of IRA is only partly attributable to a thermal mechanism, should it be also involved in photochemical ones. The cellular and molecular pathways affected by IRA are partly similar and partly different with respect to those involved in the case of visible ultraviolet A (UVA) and ultraviolet B (UVB) radiation. Consequently, the net effect of the SS is very difficult to predict at different levels of the biological organization, making more difficult the final balance of health risk and benefits (for the skin, eye, immune system, blood pressure, etc.) in a given exposure situation. Moreover, few in vivo studies and no epidemiological data are presently available in this regard. Investigating this topic may contribute to better defining the individual exposome. More practically, it is expected to bring benefits to the risk assessment and management for outdoor workers exposed to SS, contributing to: (1) better definition of the individual profiles of susceptibility, (2) more focused preventive and protective measures, (3) better implementation of the health surveillance and (4) a more effective information and training.

The Incidence of Skin Cancer in Relation to Climate Change in South Africa

Climate change is associated with shifts in global weather patterns, especially an increase in ambient temperature, and is deemed a formidable threat to human health. Skin cancer, a non-communicable disease, has been underexplored in relation to a changing climate. Exposure to solar ultraviolet radiation (UVR) is the major environmental risk factor for skin cancer. South Africa is situated in the mid-latitudes and experiences relatively high levels of sun exposure with summertime UV Index values greater than 10. The incidence of skin cancer in the population group with fair skin is considered high, with cost implications relating to diagnosis and treatment. Here, the relationship between skin cancer and several environmental factors likely to be affected by climate change in South Africa are discussed including airborne pollutants, solar UVR, ambient temperature and rainfall. Recommended strategies for personal sun protection, such as shade, clothing, sunglasses and sunscreen, may change as human behaviour adapts to a warming climate. Further research and data are required to assess any future impact of climate change on the incidence of skin cancer in South Africa.

Vitamin C mitigates heat damage by reducing oxidative stress, inducing HSP expression in TM4 Sertoli cells

Heat stress is a major stressor that can lead to male reproductive dysfunction. Sertoli cells play a crucial role in spermatogenesis by providing germ cells with structural and nutritional support, and contributing to blood-testis barrier formation. Vitamin C (Vc) is an antioxidant capable of neutralizing reactive oxygen species and preventing lipid peroxidation widely used because it is inexpensive and highly accessible. In the present study, we investigated the protective effect of Vc on TM4 cells following heat stress. Pretreatment with Vc could effectively inhibit apoptosis (p < 0.01), lipid peroxidation, and lactate dehydrogenase (LDH) activity. However, a significant increase in the malondialdehyde (MDA) level and LDH activity (p < 0.01) was observed in TM4 cells without Vc-pretreatment, in conjunction with vacuole degeneration and karyopyknosis. In addition, both the messenger RNA and protein levels of CryAB, Hsp27, Hsp70, and Hsp110 substantially increased in the 3 and 12 hr recovery groups (p < 0.01). Vc also prevented microtubule aggregation following heat stress. These results suggest that pretreatment with Vc-protected TM4 cells against heat stress by reducing the level of oxidative stress and inducing heat shock protein expression.

Hsp70 expression induced by Co-Enzyme Q10 protected chicken myocardial cells from damage and apoptosis under in vitro heat stress

The aim of this study was to investigate whether induction of Hsp70 expression by co-enzyme Q10 (Q10) treatment protects chicken primary myocardial cells (CPMCs) from damage and apoptosis in response to heat stress for 5 hours. Analysis of the expression and distribution of Hsp70 and the levels of the damage-related enzymes creatine kinase-MB (CK-MB) and lactate dehydrogenase (LDH), as well as pathological analysis showed that co-enzyme Q10 alleviated the damage caused to CPMCs during heat stress. Further, analysis of cell apoptosis and the expression of cleaved caspase-3 indicated that co-enzyme Q10 did have an anti-apoptotic role during heat stress. Western blot analysis showed that pretreatment with co-enzyme Q10 led to a significant increase in the expression of Hsp70 during heat stress. Immunostaining assays confirmed the results of western blot analysis and also showed that co-enzyme Q10 could accelerate the translocation of Hsp70 into the nucleus during heat stress, but this was not observed in the group that was treated with only co-enzyme Q10. These findings seem to indicate that co-enzyme Q10 protected CPMCs from heat stress via the induction of Hsp70. To investigate this, 200 μM quercetin, an Hsp70 inhibitor, was used to inhibit the expression of Hsp70 2 h before heat stress. Quercetin pre-treatment was observed to suppress the expression of Hsp70 as well the protective function of co-enzyme Q10 at 5 h of heat stress. This finding confirms that Q10 brought about its effects via Hsp70 expression, but the mechanism underlying this needs further investigation.

Heat shock antagonizes UVA-induced responses in murine melanocytes and melanoma cells: an unexpected interaction

The skin is under the influence of oscillatory factors such as light and temperature. This organ possesses a local system that controls several aspects in a time-dependent manner; moreover, the skin has a well-known set of opsins whose function is still unknown. We demonstrate that heat shock reduces Opn2 expression in normal Melan-a melanocytes, while the opposite effect is found in malignant B16-F10 cells. In both cell lines, UVA radiation increases the expression of Opn4 and melanin content. Clock genes and Xpa, a DNA repair gene, of malignant melanocytes are more responsive to UVA radiation when compared to normal cells. Most UVA-induced effects are antagonized by heat shock, a phenomenon shown for the first time. Based on our data, the heat produced during UV experiments should be carefully monitored since temperature represents, according to our results, an important confounding factor, and therefore it should, when possible, be dissociated from UV radiation. The responses displayed by murine melanoma cells, if proven to also take place in human melanoma, may represent an important step in cancer development and progression.

Assessment of temperature and ultraviolet radiation effects on sunburn incidence at an inland U.S. Beach: A cohort study

BACKGROUND

Increases in outdoor temperature may lead to increases in sunburn, outdoor exposure, and skin cancer in human populations.

OBJECTIVE

This study aimed to quantify sunburn incidence and risk for Ohio beachgoers exposed to varying outdoor conditions.

METHODS

Sunburn incidence data were obtained through a prospective cohort study at East Fork Lake (Cincinnati, Ohio, USA). Recruitment occurred over 26 weekend days. Beach interviews and follow-up telephone interviews obtained exposure and health information. New sunburns were self-reported 8-9 days post-enrollment. Survey data were paired with ultraviolet radiation (UVR) index and temperature data for statistical analysis.

RESULTS

Among 947 beachgoers, new sunburns were reported in 18% of swimmers. Sunburn incidence was associated with temperature (odds ratio = 1.2; 95% CI: 1.1 - 1.4) and UVR index (odds ratio = 1.6; 95% CI: 1.0 - 2.5) in models adjusted for water exposure, arrival time, and beach visit frequency. Some evidence of a temperature+UVR interaction was observed.

LIMITATIONS

Exposure and sunburn data were self-reported without clinical diagnosis and date of onset. The follow-up period enabled sunburns to be reported from a variety of days rather than only the beach visit day thereby limiting interpretation. Sun protection behaviors were not evaluated.

CONCLUSIONS

Temperature and UVR influence sunburn frequency. Temperature, however was more strongly associated with sunburn in beachgoers than the nearest measured UVR index, suggesting future investigations are needed to better understand how temperature effects sunburn development. Interventions for decreasing sunburn are needed.

SIRT1 activation mediates heat-induced survival of UVB damaged Keratinocytes

Background

Exposure to heat stress after UVB irradiation induces a reduction of apoptosis, resulting in survival of DNA damaged human keratinocytes. This heat-mediated evasion of apoptosis appears to be mediated by activation of SIRT1 and inactivation of p53 signalling. In this study, we assessed the role of SIRT1 in the inactivation of p53 signalling and impairment of DNA damage response in UVB plus heat exposed keratinocytes.

Results

Activation of SIRT1 after multiple UVB plus heat exposures resulted in increased p53 deacetylation at K382, which is known to affect its binding to specific target genes. Accordingly, we noted decreased apoptosis and down regulation of the p53 targeted pro-apoptotic gene BAX and the DNA repair genes ERCC1 and XPC after UVB plus heat treatments. In addition, UVB plus heat induced increased expression of the cell survival gene Survivin and the proliferation marker Ki67. Notably, keratinocytes exposed to UVB plus heat in the presence of the SIRT1 inhibitor, Ex-527, showed a similar phenotype to those exposed to UV alone; i.e. an increase in p53 acetylation, increased apoptosis and low levels of Survivin.

Conclusion

This study demonstrate that heat-induced SIRT1 activation mediates survival of DNA damaged keratinocytes through deacetylation of p53 after exposure to UVB plus heat

Electronic supplementary material

The online version of this article (doi:10.1186/s12895-017-0060-y) contains supplementary material, which is available to authorized users.