Simarna Kaur

Irradiation of Skin with Visible Light Induces Reactive Oxygen Species and Matrix-Degrading Enzymes

Daily skin exposure to solar radiation causes cells to produce reactive oxygen species (ROS), which are a primary factor in skin damage. Although the contribution of the UV component to skin damage has been established, few studies have examined the effects of non-UV solar radiation on skin physiology. Solar radiation comprises <10% of UV, and thus the purpose of this study was to examine the physiological response of skin to visible light (400-700 nm). Irradiation of human skin equivalents with visible light induced production of ROS, proinflammatory cytokines, and matrix metalloproteinase (MMP)-1 expression. Commercially available sunscreens were found to have minimal effects on reducing visible light-induced ROS, suggesting that UVA/UVB sunscreens do not protect the skin from visible light-induced responses. Using clinical models to assess the generation of free radicals from oxidative stress, higher levels of free radical activity were found after visible light exposure. Pretreatment with a photostable UVA/UVB sunscreen containing an antioxidant combination significantly reduced the production of ROS, cytokines, and MMP expression in vitro, and decreased oxidative stress in human subjects after visible light irradiation. Taken together, these findings suggest that other portions of the solar spectrum aside from UV, particularly visible light, may also contribute to signs of premature photoaging in skin.

A purified Feverfew extract protects from oxidative damage by inducing DNA repair in skin cells via a PI3-kinase-dependent Nrf2/ARE pathway

BACKGROUND Environmental factors such as solar ultraviolet (UV) radiation and other external aggressors provide an oxidative challenge that is detrimental to skin health. The levels of endogenous antioxidants decrease with age, thus resulting in less protection and a greater potential for skin damage. The NF-E2-related factor-2 (Nrf2) - antioxidant response element (ARE) pathway is a primary defense mechanism against oxidative stress, and induces the expression of antioxidant, detoxification and repair genes. Activation of ARE-Nrf2 can help restore oxidative homeostasis of the skin and play a role in inflammatory response and DNA repair mechanisms. OBJECTIVE To evaluate the role of a purified parthenolide-depleted Feverfew (PD-Feverfew) extract on the ARE-Nrf2 pathway and DNA repair in skin cells. METHODS These studies were undertaken in primary human keratinocytes or KB cells using Luciferase Promoter assay, siRNA transfection studies, Western blot analyses, Immunofluorescence microscopy, comet assay and quantitative real-time PCR. RESULTS PD-Feverfew was found to induce Nrf2 nuclear translocation and to increase ARE activity in a dose dependent manner. Furthermore, knockdown of Nrf2 resulted in suppression of PD-Feverfew-induced ARE activity. PD-Feverfew was also found to induce phosphorylation of Akt, a kinase downstream of PI3K. Inhibition of PI3K via pre-treatment with the selective pharmacological inhibitor, LY294002, abolished PD-Feverfew-induced Nrf2/ARE activation. PD-Feverfew also reduced UV-induced DNA damage in a PI3K and Nrf2-dependent manner. CONCLUSIONS Therefore, by increasing endogenous defense mechanisms and aid in DNA repair of damaged skin cells via activation of a PI3K-dependent Nrf2/ARE pathway, PD-Feverfew may help protect the skin from numerous environmental aggressors.

Galvanic zinc–copper microparticles produce electrical stimulation that reduces the inflammatory and immune responses in skin

The human body has its own innate electrical system that regulates the body’s functions via communications among organs through the well-known neural system. While the effect of low-level electrical stimulation on wound repair has been reported, few studies have examined the effect of electric potential on non-wounded, intact skin. A galvanic couple comprised of elemental zinc and copper was used to determine the effects of low-level electrical stimulation on intact skin physiology using a Dermacorder device. Zn–Cu induced the electrical potential recorded on intact skin, enhanced H2O2 production and activated p38 MAPK and Hsp27 in primary keratinocytes. Treatment with Zn–Cu was also found to reduce pro-inflammatory cytokines, such as IL-1α, IL-2, NO and TNF-α in multiple cell types after stimulation with PHA or Propionibacterium acnes bacteria. The Zn–Cu complex led to a dose-dependent inhibition of TNF-α-induced NF-κB levels in keratinocytes as measured by a dual-luciferase promoter assay, and prevented p65 translocation to the nucleus observed via immunofluorescence. Suppression of NF-κB activity via crosstalk with p38 MAPK might be one of the potential pathways by which Zn–Cu exerted its inflammatory effects. Topical application of Zn–Cu successfully mitigated TPA-induced dermatitis and oxazolone-induced hypersensitivity in mice models of ear edema. Anti-inflammatory activity induced by the Zn–Cu galvanic couple appears to be mediated, at least in part, by production of low level of hydrogen peroxide since this activity is reversed by the addition of Catalase enzyme. Collectively, these results show that a galvanic couple containing Zn–Cu strongly reduces the inflammatory and immune responses in intact skin, providing evidence for the role of electric stimulation in non-wounded skin.

Differential levels of elastin fibers and TGF-β signaling in the skin of Caucasians and African Americans.

BACKGROUND While skin color is the most notable difference among ethnic skins the current knowledge on skin physiological and aging properties are based mainly on Caucasian skin studies. OBJECTIVE To evaluate histological differences in elastin fiber network and differential responsiveness to TGF-β in skin of Caucasians and African Americans. METHODS These studies were undertaken using human skin biopsies, primary dermal fibroblasts, Western blot analyses, immunofluorescence microscopy, cDNA array and quantitative real-time PCR. RESULTS In Caucasian subjects, tropoelastin expression and elastin fibers in photoprotected skin was substantially less than in age-matched African American skin. Expression of tropoelastin in photoexposed skin of African American was similar to their photoprotected skin, suggesting that photoexposure did not affect elastin fibers in African American skin to the same extent as Caucasian skin. An elevated level of TGF-β1 present in media from dermal fibroblasts derived from African American skins correlated well with the higher levels of TGF-β mRNA in African American skins analyzed by cDNA array. Treatment with TGF-β1 resulted in a considerably higher induction of elastin mRNA in dermal fibroblasts from African Americans than from Caucasian fibroblasts, indicative of enhanced TGF-β signaling in African American skins. Furthermore, UVA exposure decreased levels of elastin mRNA in Caucasian fibroblasts compared to African Americans fibroblasts. CONCLUSION These results suggest that there are ethnic differences in the elastin fiber network and in TGF-β signaling in African American and Caucasian skin, and that African American have less UV dependent loss of elastin than Caucasian which may contribute to the different perceived aging phenotypes.

Induction of Prostaglandin D2 through the p38 MAPK Pathway Is Responsible for the Antipruritic Activity of Sertaconazole Nitrate

Prostaglandin D(2) (PGD(2)) is known to have antipruritic activity by suppressing histamine release. However, agents that can topically induce PGD(2) for itch relief are not well established. The antimycotic sertaconazole nitrate (STZ) has been shown to exhibit anti-itch properties; however, the mechanism for this activity has not been elucidated. STZ mitigated degranulation of RBL-2H3 (rat basophilic leukemia) mast cells induced by compound 48/80, a pruritogenic agent known to promote the release of histamine, and augmented PGD(2) production in mast cells and macrophages. Addition of exogenous PGD(2) abrogated compound 48/80-induced degranulation by acting through the prostanoid D receptor 1 (DP1). STZ induced p38 mitogen-activated protein kinase (MAPK) phosphorylation in mast cells and a pharmacological inhibitor of p38 MAPK, SB203580, resulted in the attenuation of PGD(2) levels. Finally, in a murine model of pruritus, the scratching behavior induced by compound 48/80 was mitigated by topical application of STZ. This effect was reversed by the addition of the cyclooxygenase inhibitor, ibuprofen, or a DP1 receptor antagonist (MK0524). Collectively, these results suggest that STZ mediates its anti-itch effects by boosting the antipruritic agent, PGD(2), by the activation of the p38-MAPK pathway. This is the first report to demonstrate a promising approach to topically induce PGD(2) for improving pruritus.

Regulation of DNA Repair Process by the Pro-Inflammatory NF-κB Pathway

Skin is the largest organ of the body. It is organized into three main layers, epidermis, der‐ mis and subcutaneous layer. The epidermis, an outermost avascular layer, is formed by ker‐ atinocytes at the epidermal basal layer that differentiate into corneocytes at the outer layer of the epidermis. The dermis lies below the epidermis separated by a basement membrane and is composed mainly of fibroblasts. The primary function of skin is to constitute an effi‐ cient barrier to protect the organism both from water evaporation and from external aggres‐ sions. Skin is an excellent organ system to study DNA damage and repair since skin is routinely exposed to external and internal aggressors which can induce DNA damage. Sun‐ light is the primary environmental inducer of damage in the skin. In particular ultraviolet radiations (UVR) are known to induce damage on DNA bases by direct absorption of pho‐ tons. Typical damages from the direct effect of UVR are the cyclobutane pyrimidine dimers (CPD) or the 6-4 photoproducts formation both created by dimerization of contiguous pyri‐ midines on the DNA [1]. Sunlight also induces significant damage to skin cells through the generation of Reactive Oxygen Species (ROS) which damage DNA nucleobases and the sug‐ ar phosphate backbone. Depending on the attacking ROS (singlet oxygen and hydroxyl radi‐ cals through the formation of superoxide radicals), different modifications are generated to DNA such as bulky (8-oxoguanosine, as guanine is the most easily oxidized base, thymi‐ dine and cytosine glycol) and non bulky (cyclo purine and etheno adducts) base modifica‐ tions, spontaneous hydrolysis of a normal or damaged nucleobase leading to an abasic site, (See review [2]). Finally ROS may also generate other forms of DNA damage such as single strand breaks (SSB) or double strand breaks (DSB) when the free radical attack is located on the polydeoxyribose chain. Other external aggressors, such as cigarette smoke and pollu‐

Topical stabilized retinol treatment induces the expression of HAS genes and HA production in human skin in vitro and in vivo

Skin Aging manifests primarily with wrinkles, dyspigmentations, texture changes, and loss of elasticity. During the skin aging process, there is a loss of moisture and elasticity in skin resulting in loss of firmness finally leading to skin sagging. The key molecule involved in skin moisture is hyaluronic acid (HA), which has a significant water-binding capacity. HA levels in skin decline with age resulting in decrease in skin moisture, which may contribute to loss of firmness. Clinical trials have shown that topically applied ROL effectively reduces wrinkles and helps retain youthful appearance. In the current study, ROL was shown to induce HA production and stimulates the gene expression of all three forms of hyaluronic acid synthases (HAS) in normal human epidermal keratinocytes monolayer cultures. Moreover, in human skin equivalent tissues and in human skin explants, topical treatment of tissues with a stabilized-ROL formulation significantly induced the gene expression of HAS mRNA concomitant with an increased HA production. Finally, in a vehicle-controlled human clinical study, histochemical analysis confirmed increased HA accumulation in the epidermis in ROL-treated human skin as compared to vehicle. These results show that ROL increases skin expression of HA, a significant contributing factor responsible for wrinkle formation and skin moisture, which decrease during aging. Taken together with the activity to increase collagen, elastin, and cell proliferation, these studies establish that retinol provides multi-functional activity for photodamaged skin.

4‐Hexyl‐1,3‐phenylenediol, a nuclear factor‐κB inhibitor, improves photodamaged skin and clinical signs of ageing in a double‐blinded, randomized controlled trial

The nuclear factor‐κB (NF‐κB) pathway is a key mediator of inflammation; however, few studies have examined the direct effects of NF‐κB inhibition on the skin.

The Botanical Extract Feverfew PFE Reduces DNA Damage and Induces DNA Repair Processes

Our skin is equipped with specialized cells and mechanisms that defend our bodies against pathogens, heat, and water loss. Today, our skin is exposed to increased environmental stress including solar ultraviolet radiation (which results in direct and indirect DNA damage) and atmospheric pollutants. Ozone depletion from the earth’s atmosphere as well as expanding industrial processes has led to increased exposure to pollutants including pesticides and cigarette smoke. While UV radiation, and in particular its UV-B component (280-315 nm), has several health benefits (including production of vitamin D3) (Reichrath, 2008) continuous exposure is the primary source of UV-induced DNA damage. The sun produces UV radiation classified into three broad bands. The highest energy UV-C (100-280 nm) radiation is largely absorbed by the earth’s atmosphere and thus does not affect humans. Meanwhile, the UV-B component is partially absorbed by the atmosphere and UV-A (315-400 nm) is primarily unabsorbed. While lower energy UV-A radiation penetrates beyond the epidermis, higher energy UV-B radiation primarily affects the outermost epidermal layer of skin. Harm to the body’s barrier can lead to DNA mutation or DNA replication inhibition in the skin and eyes (cataracts) and may lead to broader immunosuppression (Britt, 1995). The most serious skin cancer (malignant melanoma) occurs when excitation of a chromophore leads to either direct reaction of the excited molecule with DNA or in the production of a free radical which may also react with DNA. Since the body produces oxygen free radicals (ROS) as part of normal metabolism (during ATP production), it is able to combat oxidative stress through endogenous antioxidants. The body’s protective system, however, may become overwhelmed and compromised by environmental factors, age, or disease. Aging leads not only to increased total exposure but also to a decrease in production of endogenous antioxidants (enzymes and vitamins) and an increased risk of DNA damage. Oxidative stress can also lead to damage to other cellular components including lipids and proteins. A naturally-derived method to enhance protection against environmental factors that eventually overwhelm the body’s defense mechanisms is discussed. Another major risk of UV radiation is oxidative damage to lipids (peroxidation) and proteins. Cell membranes, which are composed of lipids, are especially