Pomegranate fruit extract inhibits UVB-induced inflammation and proliferation by modulating NF-κB and MAPK signaling pathways in mouse skin

There is considerable interest in the identification of natural agents capable of affording protection to skin from the adverse effects of solar ultraviolet B (UVB) radiation. Pomegranate (Punica granatum L.) fruit possesses as strong antioxidant, anti-inflammatory and antiproliferative properties. Recently, we have shown that oral feeding of pomegranate fruit extract (PFE) to mice afforded substantial protection from the adverse effects of single UVB radiation via modulation in early biomarkers of photocarcinogenesis. This study was designed to investigate the photochemopreventive effects of PFE (0.2%, wt/vol) after multiple UVB irradiations (180 mJ cm(-2), on alternative day, for a total of seven treatments) to the skin of SKH-1 hairless mice. Oral feeding of PFE to SKH-1 mice inhibited UVB-induced epidermal hyperplasia, infiltration of leukocytes, protein oxidation and lipid peroxidation. Immunoblot analysis demonstrated that oral feeding of PFE to mice inhibited UVB-induced (1) nuclear translocation and phosphorylation of nuclear factor kappa B/p65, (2) phosphorylation and degradation of IκBα, (3) activation of IKKα/ΙΚΚβ and (4) phosphorylation of mitogen-activated protein kinase proteins and c-Jun. PFE consumption also inhibited UVB-induced protein expression of (1) COX-2 and iNOS, (2) PCNA and cyclin D1 and (3) matrix metalloproteinases-2,-3 and -9 in mouse skin. Taken together, these data show that PFE consumption afforded protection to mouse skin against the adverse effects of UVB radiation by modulating UVB-induced signaling pathways.     

Oligonol inhibits UVB-induced COX-2 expression in HR-1 hairless mouse skin--AP-1 and C/EBP as potential upstream targets

Oxidative stress and inflammatory tissue damage are two major events frequently implicated in carcinogenesis. Numerous polyphenolic compounds derived from plants possess antioxidant and anti-inflammatory activities and are hence effective in preventing cancer. Oligonol is a polyphenol formulation enriched with catechin-type oligomers. As an initial approach to assess the chemopreventive potential of oligonol, we have determined its effects on inflammatory as well as oxidative damage in mouse skin irradiated with UVB. Topical application of oligonol onto the dorsal skin of male HR-1 hairless mice 30 min prior to UVB exposure diminished epidermal hyperplasia and formation of 4-hydroxynonenal, a biochemical hallmark of lipid peroxidation. Topical application of oligonol also significantly inhibited UVB-induced cyclooxygenase (COX-2) expression in mouse skin. Oligonol diminished the DNA binding of activator protein-1 (AP-1) and CCAAT/enhancer binding protein (C/EBP), and the expression of C/EBPdelta in mouse skin exposed to UVB. Our study also revealed that oligonol attenuated UVB-induced catalytic activity as well as expression of p38 mitogen-activated protein (MAP) kinase. Moreover, UVB-induced phosphorylation of another upstream kinase Akt was attenuated by oligonol. Taken together, oligonol showed antioxidative and anti-inflammatory effects in UVB-irradiated mouse skin by inhibiting COX-2 expression via blockade of the activation of AP-1 and C/EBP, and upstream kinases including p38 MAP kinase and Akt.     

Photoprotective Effect of Black Tea Extracts Against UVB-induced Phototoxicity in Skin

In previous studies, we showed that green tea and black tea extracts and their major polyphenolic constituents protect against UVB light-induced carcinogenesis in murine skin. All of these studies required chronic administration of tea extracts or specific constituents either topically or orally. However, it is not known whether acute or subchronic administration of black tea extracts or constituents can ameliorate UVB-induced early effects in skin. In the present study, cultured keratinocytes and mouse and human skin were employed to assess the effect of both oral and topical administration of standardized black tea extract (SBTE) and its two major polyphenolic subfractions namely BTF1 and BTF2 against UVB-induced photodamage. In SKH-1 hairless mice, topical application of SBTE (0.2 mg/cm2) prior to UVB exposure (180 mJ/cm2) resulted in 40% reduced incidence and 64% reduced severity of erythema and 50% reduction in skinfold thickness by day 6 when compared to nontreated UVB-exposed animals. The SBTE was also effective in protecting against UVB-induced erythema in human volunteers. Administration of SBTE 5 min after UVB irradiation was similarly effective in reducing UVB-induced inflammation in both murine and human skin. The major polyphenolic subfractions, BTF1 and BTF2, were also effective in protecting in mouse skin. The SBTE subfractions inhibited UVB-induced tyrosine phosphorylation of epidermal growth factor receptor (EGFR). The UVB irradiation of human epidermoid carcinoma cells resulted in 3.3-fold induction of tyrosine phosphorylation of EGFR. Pretreatment with BTF1 and BTF2 reduced tyrosine phosphorylation of EGFR by 53% and 31%, respectively. The UVB-mediated enhanced expression of the early response genes, c-fos and c-jun in human epidermal keratinocytes was reduced in a dose-dependent manner by SBTE. Topical application of SBTE was also effective in reducing accumulation of c-fos and p53 proteins by 82% and 78%, respectively, in UVB-exposed mouse skin. These data provide evidence that constituents of black tea can abrogate UVB-induced erythema and associated early events in murine and human skin.     

Cyclooxygenase-2 expression in murine and human nonmelanoma skin cancers: implications for therapeutic approaches

Inflammatory stimuli result in the production of cutaneous eicosanoids, which are known to contribute to the process of tumor promotion. Cyclooxygenase (COX), the rate-limiting enzyme for the production of prostaglandins (PG) from arachidonic acid, exists in at least two isoforms, COX-1 and COX-2. COX-1 is constitutively expressed in most tissues and plays various physiological roles, whereas increased COX-2 expression is known to occur in several types of epithelial neoplasms. Enhanced PG synthesis is a potential contributing factor in UVB-induced nonmelanoma skin cancers (NMSC). Increased COX-2 staining occurs in murine skin neoplasms after chronic exposure to carcinogenic doses of UVB. In this study, immunohistochemical and Western blot analyses were employed to assess longitudinally COX-2 expression in a standard mouse UVB complete carcinogenesis protocol and in human basal cell carcinomas (BCC) and squamous cell carcinomas (SCC). During UVB irradiation of mice, COX-2 expression consistently increased in the hyperplastic skin, the benign papillomas and the SCC. COX-2 expression was also increased in human actinic keratoses, SCC and BCC as well as in murine SCC and BCC. The pattern of COX-2 expression was quite variable, occurring in a patchy distribution in some lesions with staining confined mainly to suprabasal cell layers. In general, COX-2 expression progressively became more extensive in benign papillomas and well-differentiated murine SCC. The staining was predominantly cytoplasmic and perinuclear in some focal areas in tissue stroma around both murine and human tumors. Western blot analysis confirmed negative COX-2 expression in normal skin, whereas acute UVB exposure resulted in increased enzyme expression, which continued to increase in developing papillomas and SCC. Because of the evidence indicating a pathogenic role for eicosanoids in murine and human skin neoplasms, we performed studies to assess the anti-inflammatory and anticarcinogenic effects of green tea extracts, which are potent antioxidants. Acute exposure of the human skin to UVB (minimum erythema dose x 4) caused a transient enhancement of the COX-2 expression, which reverted to baseline within hours; however, in murine skin the expression persisted for several days. Pretreatment with the topically applied green tea extract (1 mg/cm2) largely abrogated the acute COX-2 response to UVB in mice or humans. In summary, enhanced COX-2 expression serves as a marker of epidermal UVB exposure for murine and human NMSC. These results suggest that COX-2 inhibitors could have potent anticarcinogenic effects in UVB-induced skin cancer.     

PROTECTION AGAINST ULTRAVIOLET B RADIATION-INDUCED EFFECTS IN THE SKIN OF SKH-1 HAIRLESS MICE BY A POLYPHENOLIC FRACTION ISOLATED FROM GREEN TEA

In prior studies we and others have shown that oral feeding of a polyphenolic fraction isolated from green tea (GTP) or water extract of green tea affords protection against ultraviolet B (UVB) radiation-induced carcinogenesis in SKH-1 hairless mice (Wang et al., Carcinogenesis 12, 1527–1530, 1991). It is known that exposure of murine skin to UVB radiation results in cutaneous edema, depletion of the antioxidant-defense system and induction of ornithine decarboxylase (ODC) and cyclooxygenase activities. In this study we assessed the protective effect of GTP on these UVB radiation-caused changes in murine skin. Oral feeding of 0.2% GTP (wt/vol) as the sole source of drinking water for 30 days to SKH-1 hairless mice followed by irradiation with UVB (900 mJ/cm²) resulted in significant protection against UVB radiation-caused cutaneous edema ( P <0.0005) and depletion of the antioxidant-defense system in epidermis ( P <0.01–0.02). The oral feeding of GTP also resulted in significant protection against UVB radiation-caused induction of epidermal ODC ( P <0.005–0.01) and cyclooxygenase activities ( P <0.0001) in a time-dependent manner. Our data indicate that the inhibition of UVB radiation-caused changes in these markers of tumor promotion in murine skin by GTP may be one of the possible mechanisms of chemopreventive effects associated with green tea against UVB-induced tumorigenesis. The results of this study suggest that green tea, specifically polyphenols present therein, may be useful against inflammatory responses associated with the exposure of skin to solar radiation.     

Nondenatured soy extracts reduce UVB-induced skin damage via multiple mechanisms

UV irradiation results in DNA damage, inflammation and immunosuppression, leading to the development of basal and squamous cell carcinomas. Earlier data show that topical treatment with nondenatured soy extracts reduced the incidence and delayed the development/progression of already-initiated skin tumors in high-risk hairless mice. Here we show that pretreatment with nondenatured soy extracts reduced UVB-induced Thymine-Thymine (TT) dimer formation. In vitro, nondenatured soy extracts enhanced UVB-induced checkpoint kinase-1 (Chk1) activation, suggesting a delay in cell cycle progression that enables longer time for DNA repair. Soy also reduced UVB-induced cyclo-oxygenase-2 (COX-2) expression and prostaglandin E2 secretion, and inhibited p38 MAP kinase activation, suggesting its anti-inflammatory activity. Mice pretreated topically with nondenatured soy extracts had reduced levels of UVB-induced TT dimers and COX-2 expression in their skins compared to UVB alone. The nondenatured soy extracts also inhibited vascular endothelial growth factor-induced endothelial tube formation in Matrigel, suggesting a possible inhibitory effect on angiogenesis and tumor progression. Taken together, nondenatured soy extracts could prevent or reduce UVB-induced skin damage via multiple mechanisms, affecting both the initiation and the progression of skin cancer. These data suggest that topical application of nondenatured soy extracts could potentially reduce the incidence of skin cancer.     

Photoprotective effects of bucillamine against UV-induced damage in an SKH-1 hairless mouse model

UVB exposure of skin results in various biologic responses either through direct or indirect damage to DNA and non-DNA cellular targets via the formation of free radicals, reactive oxygen species (ROS) and inflammation. Bucillamine [N-(2-mercapto-2-methylpropionyl)-l-cysteine] is a cysteine-derived compound that can replenish endogenous glutathione due to its two donatable thiol groups, and functions as an antioxidant. In this study, we investigated the effects of bucillamine on UVB-induced photodamage using the SKH-1 hairless mouse model. We have demonstrated that UVB exposure (two consecutive doses, 230 mJ cm(-2)) on the dorsal skin of SKH-1 mice induced inflammatory responses (edema, erythema, dermal infiltration of leukocytes, dilated blood vessels) and p53 activation as early as 6 h after the last UVB exposure. Bucillamine pretreatment (20 mg kg(-1) of body weight, administered subcutaneously) markedly attenuated UVB-mediated inflammatory responses and p53 activation. We have also demonstrated that the stabilization and upregulation of p53 by UVB correlated with phosphorylation of Ser-15 and Ser-20 residues of p53 protein and that bucillamine pretreatment attenuated this effect. We propose that bucillamine has potential to be effective as a photoprotective agent for the management of pathologic conditions elicited by UV exposure.     

Dietary Feeding of Opuntia Humifusa Inhibits UVB Radiation‐Induced Carcinogenesis by Reducing Inflammation and Proliferation in Hairless Mouse Model

It has been validated that ultraviolet B (UVB) irradiation induced both squamous and basal cell carcinomas, as a tumor initiator and promoter. Opuntia humifusa is a member of the Cactaceae family which has been demonstrated in our previous study to have a chemopreventive effect in 7, 12‐dimethylbenz[a]anthracene and 12‐O‐tetradecanoylphorbol‐13‐acetate induced skin carcinogenesis models. Therefore, this study was designed to determine the protective effects of O.humifusa against photocarcinogenesis. O. humifusa was administrated to mice as a dietary feeding, following exposure to UVB radiation (180 mJ/cm²) twice a week of 30 weeks for skin tumor development in hairless mice. Dietary O.humifusa inhibited UVB‐induced epidermal hyperplasia, infiltration of leukocytes, level of myeloperoxidase and the levels of proinflammatory cytokines, tumor necrosis factor‐ α (TNF‐α), interleukin‐1β (IL‐1β) and interleukin‐6 (IL‐6), in UVB exposed skin. Also, O.humifusa significantly inhibited both protein and mRNA expression level of cyclooxygenase‐2 (COX‐2), nitric oxide synthase (iNOS), proliferating cell nuclear antigen (PCNA) and cyclin D1 compared to the non‐O.humifusa treated group. Collectively, these results suggest that O.humifusa could inhibit photocarcinogenesis in mouse skin and that protective effect is associated with the inhibition of not only UVB‐induced inflammatory responses involving COX‐2, iNOS and proinflammatory cytokines, but also the down‐regulation of UVB‐induced cellular proliferation.     

Prevention of ultraviolet-B radiation damage by resveratrol in mouse skin is mediated via modulation in survivin

Nonmelanoma skin cancer is the most frequently diagnosed malignancy in the United States, and multiple exposures to solar ultraviolet (UV) radiation (particularly its UV-B component, 290-320 nm), is its major cause. 'Chemoprevention' by naturally occurring agents is being appreciated as a newer dimension in the management of neoplasia including skin cancer. We recently demonstrated that resveratrol (trans-3, 5, 4-trihydroxystilbene), an antioxidant found in grapes, red wines and a variety of nuts and berries, imparts protection from acute UV-B-mediated cutaneous damages in SKH-1 hairless mice. Understanding the mechanism of resveratrol-mediated protection of UV responses is important. We earlier demonstrated that resveratrol imparts chemopreventive effects against multiple UV-exposure-mediated modulations in (1) cki-cyclin-cdk network, and (2) mitogen activated protein kinase (MAPK)-pathway. This study was conducted to assess the involvement of inhibitor of apoptosis protein family Survivin during resveratrol-mediated protection from multiple exposures of UV-B (180 mJ/cm(2); on alternate days; for a total of seven exposures) radiations in the SKH-1 hairless mouse skin. Our data demonstrated that topical pre-treatment of resveratrol (10 micromol in 200 microl acetone/mouse) resulted in significant inhibition of UV-B exposure-mediated increases in (1) cellular proliferations (Ki-67 immunostaining), (2) protein levels of epidermal cyclooxygenase-2 and ornithine decarboxylase, established markers of tumor promotion, (3) protein and messenger RNA levels of Survivin, and (4) phosphorylation of survivin in the skin of SKH-1 hairless mouse. Resveratrol pretreatment also resulted in (1) reversal of UV-B-mediated decrease of Smac/DIABLO, and (2) enhancement of UV-B-mediated induction of apoptosis, in mouse skin. Taken together, our study suggested that resveratrol imparts chemopreventive effects against UV-B exposure-mediated damages in SKH-1 hairless mouse skin via inhibiting Survivin and the associated events.     

Photoprotection by honeybush extracts, hesperidin and mangiferin against UVB-induced skin damage in SKH-1 mice

The possible mechanism of photoprotection by polyphenolic extracts of honeybush and the two most abundant polyphenols found in honeybush, hesperidin and mangiferin were determined using a mouse model. Ethanol: acetone soluble extracts and pure honeybush compounds were applied topically to the skin of SKH-1 mice before daily exposures to ultraviolet B (UVB) (180 mJ/cm2) for 10 days. The honeybush extracts reduced signs of sunburn, such as erythema, peeling and hardening of the skin and also significantly (P < 0.05) reduced edema, epidermal hyperplasia and the induction of cyclooxygenase-2 (COX-2), ornithine decarboxylase (ODC), GADD45 and OGG1/2 expression. The fermented honeybush extract significantly (P < 0.05) reduced lipid peroxidation and depletion of the antioxidant enzymes catalase and superoxide dismutase. Hesperidin and mangiferin were less effective. These results show that extracts of honeybush and to some extent, hesperidin and mangiferin, renders protection against UVB-induced skin damage. The mechanisms investigated suggest that honeybush extracts protected the skin via modulation of induced-oxidative damage, inflammation and cell proliferation. Other specific biological properties such as modulation of signaling pathways could also be involved.     

Bucillamine Inhibits UVB-Induced MAPK Activation and Apoptosis in Human HaCaT Keratinocytes and SKH-1 Hairless Mouse Skin

Ultraviolet B (UVB) radiation is known as a culprit in skin carcinogenesis. We have previously reported that bucillamine (N-[2-mercapto-2-methylpropionyl]-L-cysteine), a cysteine derivative with antioxidant and anti-inflammatory capacity, protects against UVB-induced p53 activation and inflammatory responses in mouse skin. Since MAPK signaling pathways regulate p53 expression and activation, here we determined bucillamine effect on UVB-mediated MAPK activation in vitro using human skin keratinocyte cell line HaCaT and in vivo using SKH-1 hairless mouse skin. A single low dose of UVB (30 mJ cm⁻²) resulted in increased JNK/MAPK phosphorylation and caspase-3 cleavage in HaCaT cells. However, JNK activation and casaspe-3 cleavage were inhibited by pretreatment of HaCaT cells with physiological doses of bucillamine (25 and 100 µm ). Consistent with these results, bucillamine pretreatment in mice (20 mg kg⁻¹) inhibited JNK/MAPK and ERK/MAPK activation in skin epidermal cells at 6–12 and 24 h, respectively, after UVB exposure. Moreover, bucillamine attenuated UVB-induced Ki-67-positive cells and cleaved caspase-3-positive cells in mouse skin. These findings demonstrate that bucillamine inhibits UVB-induced MAPK signaling, cell proliferation and apoptosis. Together with our previous report, we provide evidence that bucillamine has a photoprotective effect against UV exposure.     

Oral feeding of pomegranate fruit extract inhibits early biomarkers of UVB radiation-induced carcinogenesis in SKH-1 hairless mouse epidermis

Pomegranate from the plant Punica granatum L. possesses strong antioxidant and anti-inflammatory properties. Recently, we have demonstrated that treatment of normal human epidermal keratinocytes with pomegranate fruit extract (PFE) inhibited UVB-mediated activation of nuclear factor kappa B (NF-κB) and mitogen activated protein kinases pathways. Here, we evaluated the effect of PFE on early biomarkers of photocarcinogenesis employing SKH-1 hairless mice. PFE was provided in drinking water (0.2%, wt/vol) to SKH-1 hairless mice for 14 days before a single UVB (180 mJ cm⁻²) irradiation. We found that oral feeding of PFE inhibited UVB-induced: (1) skin edema; (2) hyperplasia; (3) infiltration of leukocytes; (4) lipid peroxidation; (5) hydrogen peroxide generation; (6) ornithine decarboxylase (ODC) activity; and (7) ODC, cyclooxygenase-2 and proliferating cell nuclear antigen protein expression. Oral feeding of PFE enhanced repair of UVB-mediated formation of cyclobutane pyrimidine dimers (CPDs) and 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxodG). Importantly, PFE treatment further enhanced UVB-mediated increase in tumor suppressor p53 and cyclin kinase inhibitor p21. Furthermore, oral feeding of PFE inhibited UVB-mediated: (1) nuclear translocation of NF-κB; (2) activation of IKKα; and (3) phosphorylation and degradation of IκBα. Taken together, we provide evidence that oral feeding of PFE to mice affords substantial protection from the adverse effects of UVB radiation via modulation in early biomarkers of photocarcinogenesis and provide suggestion for its photochemopreventive potential.     

Polyphenolic antioxidant (-)-epigallocatechin-3-gallate from green tea reduces UVB-induced inflammatory responses and infiltration of leukocytes in human skin

Identification of natural products capable of affording protection against UVB radiation-induced inflammatory responses and generation of oxidative stress may have important human health implications. The UVB exposure-induced skin injury and oxidative stress has been associated with a variety of skin disease conditions including photoaging, inflammation and cancer. Tea is a popular beverage consumed worldwide. In several mouse skin models, topical application as well as oral consumption of green tea has been shown to afford protection against chemical and UVB-induced carcinogenesis and inflammatory responses. In the present study, we investigated in human skin, whether topical application of (-)-epigallocatechin-3-gallate (EGCG), the major polyphenolic constituent in green tea, inhibits UVB-induced infiltration of leukocytes (macrophage/neutrophils), a potential source of generation of reactive oxygen species (ROS), and generation of prostaglandin (PG) metabolites. Human subjects were UVB irradiated on sun-protected skin to four times their minimal erythema dosage (MED) and skin biopsies or keratomes were obtained either 24 h or 48 h later. We found that topical application of EGCG (3 mg/2.5 cm2) before UVB (4 MED) exposure to human skin significantly blocked UVB-induced infiltration of leukocytes and reduced myeloperoxidase activity. These infiltrating leukocytes are considered to be the major source of generation of ROS. In the same set of experiments we found that topical application of EGCG before UVB exposure decreased UVB-induced erythema. In additional experiments, we found that microsomes from EGCG pretreated human skin and exposed to UVB, compared to UVB exposure alone, produced significantly reduced PG metabolites, particularly PGE2. The PG metabolites play a critical role in free radical generation and skin tumor promotion in multistage skin carcinogenesis. Careful microscopic examination of skin sections, stained with hematoxylin and eosin, under higher magnification (x400) also revealed that EGCG pretreated and UVB-exposed human skin contained fewer dead cells in the epidermis with comparison to nonpretreated UVB-exposed skin. Taken together, our data demonstrate that EGCG has the potential to block the UVB-induced infiltration of leukocytes and the subsequent generation of ROS in human skin. This may explain the possible mechanism involved in anti-inflammatory effects of green tea. We suggest that EGCG may be useful as a topical agent for protection against UVB-induced ROS-associated inflammatory dermatoses, photoaging and photocarcinogenesis. Further studies are warranted in this direction.     

Dietary beta-carotene and 13-cis-retinoic acid are not effective in preventing some features of UVB-induced dermal damage in hairless mice

Albino hairless mice were fed diets containing 10 g/kg feed of beta-carotene and 200 mg/kg feed of 13-cis retinoic acid to assess the ability of these molecules to prevent UVB-induced dermal damage. Diets were administered for 12 weeks prior to UVB exposure and were continued throughout the 20 week irradiation period. The UVB source was a bank of FS-20 sunlamps (280-400 nm: peak 313 nm). Exposures were thrice weekly at 0.1 J/cm2 per exposure for the first 10 weeks and 0.2 J/cm2 per exposure for the second 10 weeks. Histologic evaluation of skin biopsies revealed no difference, between animals fed active or placebo diets, in UVB-induced elastosis, collagen changes or amounts of glycosaminoglycans and proteoglycans of the ground substance.     

Salt water bathing prior to UVB irradiation leads to a decrease of the minimal erythema dose and an increased erythema index without affecting skin pigmentation

The combination of salt water baths and solar radiation is known as an effective treatment for patients with psoriasis and atopic dermatitis. To determine whether increased susceptibility to UVB radiation may contribute to this therapeutic effect we have studied the effect of bathing the skin in salt water prior to UVB irradiation. Twelve subjects were phototested on the volar aspects of their forearms with increasing doses of UVB radiation. One forearm was exposed to 5% salt water prior to irradiation. The minimal erythema dose (MED) was determined and the erythema index and skin pigmentation were assessed by photometric measurement. The combination of salt water bath and irradiation yielded a significant decrease of the MED when compared to UVB alone (median 90 mJ/cm2 vs 130 mJ/cm2, P < 0.01). Analysis of variance showed a significant influence of salt water bath on erythema (P < 0.05) but not on skin pigmentation. Within the MED test area the erythema index of the salt water exposed forearms was elevated significantly (P < 0.05) while skin pigmentation was not affected. Thus, bathing the skin in salt water leads to a decreased threshold level for the elicitation of UVB-induced erythema and a selective increase of the erythemal response. This sensitization to the effects of shortwave UVB radiation may increase immunosuppressive effects of UVB radiation and may lead to an increased efficacy of UVB phototherapy. However, there is also an increased sunburn risk when salt water baths are followed by exposure to UV radiation.     

UV erythema reducing capacity of mizolastine compared to acetylsalicylic acid or both combined in comparison to indomethacin.

UV light exerts hazardous effects such as induction of skin cancer and premature skin aging. In this study we evaluated an assumptive anti-inflammatory effect of the nonsedative histamine H1-receptor antagonist, mizolastine, on UV-induced acute sunburn reaction. Therefore, a clinical, randomized, double-blind, four-arm, crossover study was conducted in healthy young female volunteers (skin type II) comparing the UV sensitivity under mizolastine, acetyl-salicylic acid (ASA), indomethacin or a mizolastine/ASA combination. Moreover, HaCaT keratinocytes were incubated with mizolastine under various UV treatment modalities in vitro to study its effect on the release of inflammatory cytokines, i.e. interleukin (IL)-1 alpha, IL-6 and tumor necrosis factor alpha (TNF-alpha). All three drugs were effective in suppressing the UVB-, UVA- and combined UVA/UVB-erythema. However, the strongest effects were observed using the combined treatment with both 250 mg ASA and 10 mg mizolastine. An inhibitory effect in vitro of 10 nM mizolastine upon UV-induced cytokine release from HaCaT keratinocytes was observed for IL-1 alpha at 24 h after 10 J/cm2 UVA1, for IL-6 at 48 h after 10 J/cm2 UVA1 and 30 mJ/cm2 UVB, and also for TNF-alpha at 4 h after 10 J/cm2 UVA, 10 J/cm2 UVA1 and 30 mJ/cm2 UVB, respectively. The combination of mizolastine and ASA can be strongly recommended as a protective measure against UV erythema development with a lower unwanted side effect profile than that of the hitherto treatment modality, i.e. indomethacin.     

Usnea barbata extract prevents ultraviolet-B induced prostaglandin E2 synthesis and COX-2 expression in HaCaT keratinocytes

Usnea barbata and its major constituent usnic acid are potent antimicrobial agents. Here, we have investigated anti-inflammatory properties of an U. barbata extract (UBE) containing 4% usnic acid in an ultraviolet-B (UVB) model with HaCaT keratinocytes. UVB irradiation induced PGE(2) production and COX-2 expression in a time and dose-dependent manner. UBE inhibited PGE(2) production at a half-maximal concentration of 60 microg/ml (2.4 microg/ml usnic acid) that did not affect the UVB-induced upregulation of COX-2, suggesting an effect on enzyme activity rather than on protein expression. The inhibition of PGE(2) production by UBE was not due to cytotoxicity. Besides its known antimicrobial properties, UBE displays specific UVB protective effects that might be useful in the topical treatment of UVB-mediated inflammatory skin conditions.