Christoph M. Schempp

Contact sensitizers induce skin inflammation via ROS production and hyaluronic acid degradation.

Background Allergic contact dermatitis (ACD) represents a severe health problem with increasing worldwide prevalence. It is a T cell-mediated skin disease induced by protein-reactive organic and inorganic chemicals. A key feature of contact allergens is their ability to trigger an innate immune response that leads to skin inflammation. Previous evidence from the mouse contact hypersensitivity (CHS) model suggests a role for endogenous activators of innate immune signaling. Here, we analyzed the role of contact sensitizer induced ROS production and concomitant changes in hyaluronic acid metabolism on CHS responses. Methodology/Principal Findings We analyzed in vitro and in vivo ROS production using fluorescent ROS detection reagents. HA fragmentation was determined by gel electrophoresis. The influence of blocking ROS production and HA degradation by antioxidants, hyaluronidase-inhibitor or p38 MAPK inhibitor was analyzed in the murine CHS model. Here, we demonstrate that organic contact sensitizers induce production of reactive oxygen species (ROS) and a concomitant breakdown of the extracellular matrix (ECM) component hyaluronic acid (HA) to pro-inflammatory low molecular weight fragments in the skin. Importantly, inhibition of either ROS-mediated or enzymatic HA breakdown prevents sensitization as well as elicitation of CHS. Conclusions/Significance These data identify an indirect mechanism of contact sensitizer induced innate inflammatory signaling involving the breakdown of the ECM and generation of endogenous danger signals. Our findings suggest a beneficial role for anti-oxidants and hyaluronidase inhibitors in prevention and treatment of ACD.

Hypericin photo-induced apoptosis involves the tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and activation of caspase-8

Hypericin (HYP) is a photosensitizing pigment from Hypericum perforatum that displays cytotoxic effects in neoplastic cell lines. Therefore, HYP is presently under consideration as a new anticancer drug in photodynamic therapy. Here, we investigated the mechanism of action of HYP photo‐induced apoptosis of Jurkat cells compared to the cytostatic drug paclitaxel (PXL). Both photoactivated HYP and PXL similarly increased the activity of caspase‐8 and caspase‐3, and drug‐induced apoptosis of Jurkat cells was completely blocked by inhibitors of caspase‐8 (Z‐IETD‐FMK) and caspase‐3 (Z‐DEVD‐FMK). The involvement of death receptors was analyzed using neutralizing monoclonal antibodies against Fas (SM1/23), FasL (NOK‐2) and TNF‐R1 (MAB225), and a polyclonal rabbit anti‐human TNF‐related apoptosis‐inducing ligand (TRAIL) antiserum. TRAIL antibody blocked TRAIL‐induced and HYP photo‐induced, but not PXL‐induced apoptosis of Jurkat cells. In contrast, PXL‐induced, but not HYP‐induced apoptosis was blocked by the SM1/23 and NOK‐2 antibodies. Anti‐TNF‐R1 antibody had no effect. These findings suggest that HYP photo‐induced apoptosis of Jurkat cells is mediated in part by the TRAIL/TRAIL‐receptor system and subsequent activation of upstream caspases.

In vivo photoprotective and anti-inflammatory effect of hyperforin is associated with high antioxidant activity in vitro and ex vivo.

Hyperforin, a major constituent of St. Johns Wort (Hypericum perforatum, HP), provides anti-inflammatory, anti-tumor, and anti-bacterial properties. Previous studies have shown anti-oxidative properties of St. Johns Wort extracts; however, its free radical scavenging activity in skin cells or skin has not been assessed in detail so far. Therefore, the free radical scavenging activity of hyperforin was tested in the H(2)DCFDA-assay in vitro in HaCaT keratinocytes irradiated with solar simulated radiation. Hyperforin (EC(50) 0.7 μM corresponding to 0.42 μg/ml) was much more effective compared to Trolox (EC(50) 12 μg/ml) and N-acetylcysteine (EC(50) 847 μg/ml) without showing phototoxicity. The radical protection factor of a cream containing 1.5%w/w of a hyperforin-rich HP extract was determined to be 200 × 10(14) radicals/mg, indicating a high radical scavenging activity. The cream was further applied ex vivo on porcine ear skin and significantly reduced radical formation after infrared irradiation. Finally, the UV-protective effect of the HP cream was tested on 20 volunteers in a randomized, double-blind, vehicle-controlled study. HP cream significantly reduced UVB-induced erythema as opposed to the vehicle. Occlusive application of HP cream on non-irradiated test sites did not cause any skin irritation. Taken together, these results demonstrate that hyperforin is a powerful free radical scavenger.

Which plant for which skin disease? Part 1: Atopic dermatitis, psoriasis, acne, condyloma and herpes simplex

Plant extracts and isolated compounds are increasingly used in cosmetics and food supplements to improve skin conditions. We first introduce the positive plant monographs with dermatological relevance of the former German Commission E. Subsequently clinical studies with botanicals for atopic dermatitis, psoriasis, acne, condylomata acuminata and herpes simplex are discussed. The best studies have been conducted with atopic dermatitis and psoriasis patients. Mahonia aquifolium, Hypericum perforatum, Glycyrrhiza glabra and certain traditional Chinese therapies have been shown to be effective in the treatment of atopic dermatitis. Mahonia aquifolium, Indigo naturalis and Capsicum frutescens are effective treatments for psoriasis. Green tea extract and tea tree oil have been investigated in the treatment of acne. Podophyllin and green tea extract are effective treatments for condylomata acuminata. Balm mint and a combination of sage and rhubarb have been shown to be effective in the treatment of herpes simplex in proof of concept studies.

Hypericin Levels in Human Serum and Interstitial Skin Blister Fluid after Oral Single-Dose and Steady-State Administration of Hypericum perforatum Extract (St. John’s Wort)

The photodynamically active plant pigment hypericin, a characteristic metabolite of Hypericum perforatum (St. John’s wort), is widely used as an antidepressant. When administered orally, phototoxic symptoms may limit the therapeutic use of hypericin-containing drugs. Here we describe the high-performance liquid chromatographic (HPLC) detection of hypericin and semiquantitative detection of pseudohypericin in human serum and skin blister fluid after oral single-dose (1 × 6 tablets) or steady-state (3 × 1 tablet/day, for 7 days) administration of the Hypericum extract LI 160 in healthy volunteers (n = 12). Serum levels of hypericin and pseudohypericin were always significantly higher than skin levels (p ≤ 0.01). After oral single-dose administration of Hypericum extract the mean serum level of total hypericin (hypericin + pseudohypericin) was 43 ng/ml and the mean skin blister fluid level was 5.3 ng/ml. After steady-state administration the mean serum level of total hypericin was 12.5 ng/ml and the mean skin blister fluid level was 2.8 ng/ml. These skin levels are far below hypericin skin levels that are estimated to be phototoxic (>100 ng/ml).

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.

Abstract— 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/cm2vs 130 mJ/cm2P < 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.

A Novel Triterpene Extract from Mistletoe Induces Rapid Apoptosis in Murine B16.F10 Melanoma Cells

The European mistletoe Viscum album L. is a plant used for remedies in cancer treatment. The benefit of commonly used aqueous extracts is controversial but the plant contains water insoluble triterpene acids providing interesting anticancer properties. Triterpene extracts (TE) from plants and single triterpenoids such as oleanolic acid (OA) or betulinic acid (BA) are known for their cytotoxic effects on cancer cell lines in vitro. We report here cytotoxic effects of a novel OA‐rich triterpene extract from mistletoe (V. album L., Santalaceae) solubilized by 2‐hydroxypropyl‐β‐cyclodextrin (2‐HP‐β‐CD) on B16.F10 mouse melanoma cells. The 2‐HP‐β‐CD solubilized triterpene extract (STE) was highly cytotoxic by causing DNA fragmentation, followed by loss of membrane integrity and intracellular adenosine‐5′‐triphosphate (ATP). Blocking the caspase machinery by inhibitors aborted DNA fragmentation and delayed the cytotoxic effects but did not prevent cell death. The solubilization by 2‐HP‐β‐CD allows a solvent‐free application of triterpene extracts in the in vitro setting. These findings suggest the use of STE from mistletoe as a solvent‐free anticancer drug for preclinical animal experiments and clinical trials. Copyright

Durch Pflanzen ausgelöste toxische und allergische Dermatitis (Phytodermatitis)

ZusammenfassungPflanzenextrakte werden zunehmend bei der Herstellung von Kosmetika, Pflegeprodukten und anderen dermatologischen Externa verwendet. In Kosmetika enthaltene Pflanzenextrakte von Teebaum, Arnika, Kamille, Schafgarbe, Zitrusfrüchten, Efeu, Aloe, Lavendel, Rosmarin und Pfefferminze können eine Kontaktallergie auslösen. Die einzelnen Pflanzen weisen allerdings ein unterschiedliches Sensibilisierungspotenzial auf. Die häufigsten Kontaktallergene sind Sesquiterpenlaktone und Terpene. In der vorliegenden Übersicht wird ein aktueller Überblick über Formen der Phytodermatitis gegeben. Neben hautreizenden (irritativen) und phototoxischen Reaktionen werden photoallergische Reaktionen, die Allergie vom Soforttyp (Kontakturtikaria) und die Allergie vom verzögerten Typ beobachtet. Die aeroallergene Kontaktdermatitis ist eine Sonderform der Kontaktdermatitis, sie tritt gelegentlich als Mischform zwischen einer phototoxischen und einer allergischen Dermatitis auf.AbstractHerbal products are being used increasingly for medical or cosmetic purposes. Many cosmetics contain plant extracts for fragrance. Sensitizing plants in cosmetics are tea tree oil, arnica, chamomile, yarrow, citrus extracts, common ivy, aloe, lavender, peppermint, and others. However, the sensitizing potential of these plants varies. Most of the sensitizing substances are sesquiterpene lactones or terpenes. The present paper reviews the various forms of phytodermatitis, including irritant plant dermatitis, phototoxic and photoallergic dermatitis, allergic dermatitis, and airborne contact dermatitis.

Effect of topical application of Hypericum perforatum extract (St. John's wort) on skin sensitivity to solar simulated radiation.

St. Johns wort (Hypericum perforatum) is a tradional folk remedy that is used for the topical treatment of superficial wounds, scars and burns. A characteristic metabolite of St. Johns wort is the photodynamic active plant pigment hypericin. It is known that hypericin may cause a severe photodermatitis called hypericism when higher amounts of St. Johns wort are ingested orally. To date, no reports on the photosensitizing capacity of topical application of St. Johns wort are available. Here, we investigated the effects of Hypericum oil (hypericin 110 μg/mL) and Hypericum ointment (hypericin 30 μg/mL) on skin sensitivity to solar simulated radiation. Sixteen volunteers of the skin types II and III were tested on their volar forearms with solar simulated radiation for photosensitizing effects of Hypericum oil (n=8) and Hypericum ointment (n=8). The minimal erythema dose (MED) was determined by visual assessment, and skin erythema was evaluated photometrically. With the visual erythema score, no change of the MED could be detected after application of either Hypericum oil or Hypericum ointment (P>0.05). With the more sensitive photometric measurement, an increase of the erythema‐index after treatment with the Hypericum oil could be detected (P≤0.01). The results do not provide evidence for a severe phototoxic potential of Hypericum oil and Hypericum ointment, detectable by the clinically relevant visual erythema score. However, the trend towards increased photosensitivity detected with the more sensitive photometric measurement could become relevant in fair‐skinned individuals, in diseased skin or after extended solar irradiation.

Which plant for which skin disease? Part 2: Dermatophytes, chronic venous insufficiency, photoprotection, actinic keratoses, vitiligo, hair loss, cosmetic indications

This paper continues our review of scientifically evaluated plant extracts in dermatology. After plants effective against dermatophytes, botanicals with anti‐edema effects in chronic venous insufficiency are discussed. There is good evidence from randomized clinical studies that plant extracts from grape vine leaves (Vitis vinifera), horse chestnut (Aesculus hippocastanum), sea pine (Pinus maritima) and butchers broom (Ruscus aculeatus) can reduce edema in chronic venous insufficiency. Plant extracts from witch hazel (Hamamelis virginiana), green tea (Camellia sinensis), the fern Polypodium leucotomos and others contain antioxidant polyphenolic compounds that may protect the skin from sunburn and photoaging when administered topically or systemically. Extracts from the garden spurge (Euphorbia peplus) and from birch bark (Betula alba) have been shown to be effective in the treatment of actinic keratoses in phase II studies. Some plant extracts have also been investigated in the treatment of vitiligo, various forms of hair loss and pigmentation disorders, and in aesthetic dermatology.