The role of near infrared radiation in photoaging of the skin

Highly efficient proteolysis accelerated by electromagnetic waves for Peptide mapping

Proteomics will contribute greatly to the understanding of gene functions in the post-genomic era. In proteome research, protein digestion is a key procedure prior to mass spectrometry identification. During the past decade, a variety of electromagnetic waves have been employed to accelerate proteolysis. This review focuses on the recent advances and the key strategies of these novel proteolysis approaches for digesting and identifying proteins. The subjects covered include microwave-accelerated protein digestion, infrared-assisted proteolysis, ultraviolet-enhanced protein digestion, laser-assisted proteolysis, and future prospects. It is expected that these novel proteolysis strategies accelerated by various electromagnetic waves will become powerful tools in proteome research and will find wide applications in high throughput protein digestion and identification.

Infrared radiation does not enhance the frequency of ultraviolet radiation-induced skin tumors, but their growth behaviour in mice

There is increasing concern about the interaction between infrared radiation (IR) and ultraviolet radiation (UVR) with regard to carcinogenesis because prolonged solar exposure is associated with an increased cumulative load not only of UVR but also of IR. We recently demonstrated that IR-pretreatment reduces UVR-induced apoptosis. As this might support the survival of UVR-damaged cells and thus carcinogenesis, we performed an in vivo photocarcinogenesis study. One group of mice were treated with IR prior to each UVR exposure; additional groups were treated with IR or UVR alone. IR alone did not induce skin cancer. UVR-induced tumor formation was not enhanced in IR-pretreated mice, but, in contrast, seemed to occur with delay. This correlated with a reduction of p53 mutated clones in the skin. However, once developed, tumors in IR-pretreated mice grew faster which was confirmed by their enhanced Ki-67 expression. The enhanced aggressiveness of tumors derived from IR-pretreated mice was associated with a higher prevalence of sarcomas than epithelial tumors. Hence, the impact of IR on UVR-induced carcinogenesis has to be interpreted with caution. Although IR may delay the onset of UVR-induced tumors, it might contribute to a worse outcome by shifting these tumors into a more aggressive phenotype.

Photoaging under recreational sunbeds

BACKGROUND

Artificial sources of restricted light wavelength, particularly tanning beds, are progressively gaining importance in photoaging.

OBJECTIVE

To assess the kinetics and the long-term evolution of skin pigmentation and tensile functions in sunbed worshippers over a period of 8 years.

METHODS

Photoaging was explored in women who were both sunshine and sunbed worshippers. A series of 65 phototype III women aged 31-46 years completed a 100-month survey. Quarterly assessments were performed on the forearms to measure (a) the skin color individual typology angle (ITA°), (b) the extent in mottled subclinical melanoderma (MSM) using the ultraviolet light-enhanced visualization method and (c) the rheological properties of skin.

RESULTS

A progressive increase in both skin extensibility and hysteresis was observed, contrasting with a decrease in biologic elasticity. These rheological changes were correlated with the ITA° changes, but not with the MSM extent. The kinetics of evolution of each test variable were distinct over time.

DISCUSSION

This work is the first attempt at evaluating the kinetics of changes in physical parameters during a long period of frequent exposures to tanning sunbeds and sunshine for lifestyle purposes. The alterations were quite important in the color, MSM and rheological functions of the skin.

Ultraviolet radiation and skin cancer

Skin cancer is the most common type of cancer in fair-skinned populations in many parts of the world. The incidence, morbidity and mortality rates of skin cancers are increasing and, therefore, pose a significant public health concern. Ultraviolet radiation (UVR) is the major etiologic agent in the development of skin cancers. UVR causes DNA damage and genetic mutations, which subsequently lead to skin cancer. A clearer understanding of UVR is crucial in the prevention of skin cancer. This article reviews UVR, its damaging effects on the skin and its relationship to UV immunosuppression and skin cancer. Several factors influence the amount of UVR reaching the earth's surface, including ozone depletion, UV light elevation, latitude, altitude, and weather conditions. The current treatment modalities utilizing UVR (i.e. phototherapy) can also predispose to skin cancers. Unnecessary exposure to the sun and artificial UVR (tanning lamps) are important personal attributable risks. This article aims to provide a comprehensive overview of skin cancer with an emphasis on carefully evaluated statistics, the epidemiology of UVR-induced skin cancers, incidence rates, risk factors, and preventative behaviors & strategies, including personal behavioral modifications and public educational initiatives.

Solar radiation induced skin damage: review of protective and preventive options

PURPOSE

Solar energy has a number of short- and long-term detrimental effects on skin that can result in several skin disorders. The aim of this review is to summarise current knowledge on endogenous systems within the skin for protection from solar radiation and present research findings to date, on the exogenous options for such skin photoprotection.

RESULTS

Endogenous systems for protection from solar radiation include melanin synthesis, epidermal thickening and an antioxidant network. Existing lesions are eliminated via repair mechanisms. Cells with irreparable damage undergo apoptosis. Excessive and chronic sun exposure however can overwhelm these mechanisms leading to photoaging and the development of cutaneous malignancies. Therefore exogenous means are a necessity. Exogenous protection includes sun avoidance, use of photoprotective clothing and sufficient application of broad-spectrum sunscreens as presently the best way to protect the skin. However other strategies that may enhance currently used means of protection are being investigated. These are often based on the endogenous protective response to solar light such as compounds that stimulate pigmentation, antioxidant enzymes, DNA repair enzymes, non-enzymatic antioxidants.

CONCLUSION

More research is needed to confirm the effectiveness of new alternatives to photoprotection such as use of DNA repair and antioxidant enzymes and plant polyphenols and to find an efficient way for their delivery to the skin. New approaches to the prevention of skin damage are important especially for specific groups of people such as (young) children, photosensitive people and patients on immunosuppressive therapy. Changes in public awareness on the subject too must be made.

Infrared A radiation influences the skin fibroblast transcriptome: mechanisms and consequences

Infrared A (IRA) radiation (760-1440 nm) is a major component of solar radiation and, similar to UVR, causes photoaging of human skin by increasing the expression of matrix metalloproteinase-1 in human skin fibroblasts. In this study, we assessed the IRA-induced transcriptome in primary human skin fibroblasts. Microarray analysis revealed 599 IRA-regulated transcripts. The IRA-induced transcriptome differed from changes known to be induced by UV. IRA-responsive genes include the categories extracellular matrix, calcium homeostasis, stress signaling, and apoptosis. Selected results were confirmed by real-time PCR experiments analyzing 13 genes representing these four categories. By means of chemical inhibitors of known signaling pathways, we showed that ERK1/2, the p38-, JNK-, PI3K/AKT-, STAT3-, and IL-6 as well as the calcium-mediated signaling pathways, are functionally involved in the IRA gene response and that a major part of it is triggered by mitochondrial and, to a lesser extent, non-mitochondrial production of reactive oxygen species. Our results identify IRA as an environmental factor with relevance for skin homeostasis and photoaging.

Near-infrared photoinactivation of bacteria and fungi at physiologic temperatures

We examined a laser system (870 and 930 nm), employing wavelengths that have exhibited cellular photodamage properties in optical traps. In vitro, with 1.5 cm diameter flat-top projections (power density of 5.66 W cm(-2)), at physiologic temperatures, we achieved photoinactivation of Staphylococcus aureus, Escherichia coli, Candida albicans and Trichophyton rubrum. Using nonlethal dosimetry, we measured a decrease in trans-membrane potentials (DeltaPsimt and DeltaPsip) and an increase in reactive oxygen species (ROS) generation in methicillin-resistant S. aureus (MRSA), C. albicans and human embryonic kidney cells. We postulate that these multiplexed wavelengths cause an optically mediated mechano-transduction of cellular redox pathways, decreasing DeltaPsi and increasing ROS. The cellular energetics of prokaryotic and fungal pathogens, along with mammalian cells, are affected in a similar manner when treated with these multiplexed wavelengths at the power densities employed. Following live porcine thermal tolerance skin experiments, we then performed human pilot studies, examining photodamage to MRSA in the nose and fungi in onychomycosis. No observable damage to the nares or the nail matrix was observed, yet photodamage to the pathogens was achieved at physiologic temperatures. The selective aspect of this near-infrared photodamage presents the possibility for its future utilization in human cutaneous antimicrobial therapy.

Modulation of tropoelastin and fibrillin-1 by infrared radiation in human skin in vivo

BACKGROUND

The heat produced by exposure to infrared radiation (IR) has been demonstrated to modulate the expression of tropoelastin and fibrillin-1, the two main components of elastic fibers in human skin in vivo. However, the effect of IR range of radiations on tropoelastin and fibrillin-1 expression has not been thoroughly investigated.

METHODS

Eighteen volunteers were enrolled in this study involving three trials. Time-dependent, dose-dependent and cumulative effects of IR were investigated, respectively. Tropoelastin and fibrillin-1 expression was measured by immunohistochemical staining on skin biopsy samples from volunteers. In addition, we also measured tropoelastin mRNA expression by a real-time RT-polymerase chain reaction.

RESULTS

A single dose of IR (2 minimal heating dose) induced a time-dependent increase in tropoelastin expression at the protein level. An inverse correlation was found between the alterations of tropoelastin and fibrillin-1. Furthermore, IR was found to increase tropoelastin expression in a dose-dependent manner at both the mRNA and the protein level. Repeated low doses of IR increased tropoelastin expression and decreased fibrillin-1 expression at the protein level in the dermis. Meanwhile, the number of both fibers along the dermal-epidermal junction was increased.

CONCLUSION

IR can alter the expression of tropoelastin and fibrillin-1, which may result in abnormal elastic fiber formation.

Role of mitochondria in photoaging of human skin: the defective powerhouse model

The exact pathogenesis of photoaging of the skin is not yet known. Earlier, a number of molecular pathways explaining one or more characteristics of photoaged skin have been described, but a unifying mechanistic concept is still missing. Here we propose the "Defective Powerhouse Model of Premature Skin Aging", which reconciles most of the earlier conducted research as one concept. In this model, the persistence of UV radiation-induced mtDNA deletions or the infrared radiation-induced disturbance of the electron flow of the mitochondrial electron transport chain leads to inadequate energy production in dermal fibroblasts. As a consequence of this defective powerhouse, retrograde mitochondrial signaling pathways are triggered that then they transduce functional and structural alterations in the skin. This model, which is supported by a growing number of recent studies, is of direct clinical importance in preventing and treating photoaging in human skin.Journal of Investigative Dermatology Symposium Proceedings (2009) 14, 44-49; doi:10.1038/jidsymp.2009.1.

The benefits and risks of ultraviolet tanning and its alternatives: the role of prudent sun exposure

Sunlight- and indoor ultraviolet (UV)-induced tanning is a common behavior, especially among adolescents, young adults, and individuals who have lighter skin. Excessive sun exposure is associated with several health risks, including the acceleration of skin aging and the promotion of skin cancers. Several health benefits of UV exposure include vitamin D production and improved mood. This article analyzes these health risks and benefits and discusses pertinent issues surrounding indoor tanning, the role of sunless tanning products, and prudent sun exposure.

The benefits and risks of ultraviolet tanning and its alternatives: the role of prudent sun exposure

Sunlight- and indoor ultraviolet (UV)-induced tanning is a common behavior, especially among adolescents, young adults, and individuals who have lighter skin. Excessive sun exposure is associated with several health risks, including the acceleration of skin aging and the promotion of skin cancers. Several health benefits of UV exposure include vitamin D production and improved mood. This article analyzes these health risks and benefits and discusses pertinent issues surrounding indoor tanning, the role of sunless tanning products, and prudent sun exposure.