Katharine Martin

The influence of the response of skin equivalent systems to topically applied consumer products by epithelial--mesenchymal interactions.

A number of diverse in vitro model systems have been employed for the prediction of irritation potential of test articles. Monolayer systems have proven to be useful for preliminary screening but are not always capable of distinguishing mild effects or adaptable to fully formulated product. Three-dimensional reconstructed skin equivalents integrate cellular toxicity with the kinetics of exposure and absorption, serving as more realistic models; however, it is not obvious which of the three-dimensional models will give the most predictive response, and which biomarker should be used for an endpoint measurement for different groups of irritants. While evaluating these variables, we have shown that different irritants modulate various cytokine mRNA levels and secretion patterns in a time- and concentration-dependent manner that is unique to each product category. These profiles are also dependent on keratinocyte-fibroblast interactions. The most predictive combinations of model systems and biomarkers for each product category were identified following comparison to preclinical data and human in vivo skin responses. Using a panel of representative consumer products, we identified IL-1alpha, IL-1ra, IL-8 and GM-CSF release from skin equivalents as being the best indicators of irritation.

Development of Solar UVR-Related Pigmentation Begins as Early as the First Summer of Life

regenerated from intact melanophores. At 0.9 J cm 2 fluence, destroyed melanophores should be generated from stem cells, and they therefore required more time to regenerate in our study. Melanosomes in melanophores of adult zebrafish normally have a round or slightly ellipsoid shape (Hirata et al., 2005). In contrast, the damaged melanosomes in our study appeared shrunken or cracked after laser irradiation (Supplementary Figure S2 online). With the exception of the melanosomes, no other cells were observed to be damaged by transmission electron microscopy. Xanthophores—the source of the yellow stripes on zebrafish skin—are hypothesized to act as a barrier delimiting the area that can be occupied by melanophores. The interactions between these two types of chromatophores are an important focus in the study of zebrafish pigmentation patterns (Takahashi and Kondo, 2008). After Q-switched Nd:YAG laser irradiation, intact xanthophores were detected (Supplementary Figure S3 online). Recently, attempts have been made to use the 1064-nm Q-switched Nd:YAG laser with short pulse duration and low fluence for the treatment of melasma (Jeong et al., 2008; Polnikorn, 2008; Chung et al., 2009; Kim et al., 2009). With short pulse duration and low fluence, the laser could selectively photothermolyse melanosomes without killing melanocytes. This might prevent postinflammatory hyperpigmentation after melanocyte destruction, which is especially common in Asians (Ho and Chan, 2009). In addition, our study offers a convenient technique to destroy melanosomes in adult zebrafish. The Qswitched Nd:YAG laser can be used to remove melanosomes without affecting melanophores or other cells at the following settings : 1064 nm wavelength, 5–7 ns pulse duration, 7 mm spot size, and 0.4 J cm 2 fluence. Although they are very specific settings, and subtle changes might therefore invalidate the use of this model, the approaches used here may be helpful for the study of melanocyte biology with zebrafish.

Anti-Inflammatory Activity of Parthenolide-Depleted Feverfew (Tanacetum parthenium)

Abstract.Extracts of Tanacetum parthenium (L.) Sch. Bip., a plant known under the common name “Feverfew”, contains the sesquiterpene lactone parthenolide, a potent skin sensitizer. To eliminate the risk of skin sensitization from Feverfew, we developed a parthenolide-depleted extract of Feverfew (PD-Feverfew) and determined its effectiveness as an anti-inflammatory agent. We confirmed that PD-Feverfew was sufficiently depleted of parthenolide since PD-Feverfew did not inhibit TNF-α induced-NF-κB activity unlike parthenolide containing whole Feverfew. PD-Feverfew directly inhibited the activity of pro-inflammatory enzymes 5-lipoxygenase, phosphodiesterase-3 and phosphodiesterase-4. PD-Feverfew inhibited the release of pro-inflammatory mediators nitric oxide, PGE2 and TNF-α from macrophages and TNF-α, IL-2, IFN-γ and IL-4 from human peripheral blood mononuclear cells. Additionally, PD-Feverfew inhibited TPA-induced release of PGE2 from human skin equivalents. In vivo, PD-Feverfew inhibited oxazolone-induced dermatitis, and was more potent than whole Feverfew in reducing TPA-induced dermatitis. Finally the efficacy of PD-Feverfew was confirmed clinically by a reduction in erythema in a methyl nicotinate-induced vasodilation model. In conclusion, our results indicate that PD-Feverfew extracts have potent anti-inflammatory activity suggesting that this botanical would be efficacious in relieving inflammation without inducing immune sensitization.

Using Novel In Vitro NociOcular Assay based on TRPV1 channel activation for Prediction of Eye Sting Potential of Baby Shampoos

The transient receptor potential vanilloid type 1 (TRPV1) channel is one of the most well-characterized pain-inducing receptors. The purpose of this study was to predict human eye stinging of 19 baby bath and shampoo formulations by studying TRPV1 activity, as measured by increase in intracellular free Ca(2+). The NociOcular test, a novel recombinant neuronal in vitro model with high expression of functional TRPV1 channels, was used to test formulations containing a variety of surfactants, preservatives, and fragrances. TRPV1-specific Ca(2+) influx was abolished when the TRPV1 channel antagonist capsazepine was applied to the cells prior to shampoo samples. The positive control, an adult shampoo that contains cocamide monoethanolamine (CMEA), a known stinging ingredient, was the most active sample tested in the NociOcular test. The negative control, a marketed baby shampoo, was negative in the NociOcular and human tests. Seven of the formulations induced stinging in the human test, and of those six were positive in the NociOcular test. Twelve formulations were classified as nonstinging in the human test, and of those ten were negative in the NociOcular test. There was no correlation between the clinical stinging results for the baby formulations and the data generated from other in vitro eye irritation assays (cytosensor microphysiometer, neutral red uptake, EpiOcular, transepithelial permeability). Our data support that the TRPV1 channel is a principal mediator of eye-stinging sensation induced by baby bath and shampoo formulations and that the NociOcular test may be a valuable in vitro tool to predict human eye-stinging sensation.