d A, including the calgranulin A and B family members, small proline-rich Fig. 2. Heatmap of select genes down-regulated in OVA skin patch treated with Compound A. Total RNA was extracted and analyzed using Illumina beadarrays. Levels of gene expression in OVA skin patch 6 Compound A were compared with mice treated with just a PBS skin patch. Data are presented as fold increase or decrease in OVA skin patch 6 Compound A relative to mice treated with a PBS skin patch. The data array is representative of three independent experiments. The fold changes are noted on the respective color scales. In the clustergrams, genes are grouped 
into cytokines, cytokine receptors, CC chemokines, CC chemokine receptors and CXC chemokines. CD antigens, mucin cluster and adenosine pathway. Arachidonic acid pathway, signaling molecules and R-115777 transcription factors. Levels of CD3c antigen, IL-1b, CD14 antigen and calcium-binding protein A9 gene expression as determined by RT qPCR. The data were normalized relative to b-actin and are presented as fold increase or decrease in OVA skin patch 6 Compound A relative to mice treated with a PBS skin patch. The RTqPCR is representative of two independent experiments performed in duplicate. CRTH2 blocks OVA-induced skin inflammation 7 Fig. 2. continued. protein 2A and the IL-4 receptor a-chain. The qPCR analysis showed an almost complete inhibition of IL-1b RNA induced by OVA treatment. Similarly, qPCR analysis of OVA-sensitized skin sections demonstrated that RNA levels of CD14, CD3c and the atopy-linked gene S100a9 were strongly reduced in mice that received Compound A compared with the drug vehicle-treated animals. Finally, it should be noted that the qPCR data on a selection of genes confirm the microarray analysis for the genes examined. In addition to examining RNA expression patterns from patched skin, protein lysates were also made, and local production of cytokines was examined. In line with the gene expression analysis, both MIP-1b and IL-1b protein levels were elevated in OVA-sensitized skin compared with the PBS control skin sections. However, the administration of Compound A during the sensitization period significantly re- duced the levels of these pro-inflammatory factors. A similar reduction was seen with IL-4, where levels in the OVApatched skin were almost 3-fold greater than PBS-patched skin, and the administration of either Compound A p.o. or i.p. dexamethasone lowered IL-4 levels to that of PBS controls. As has been previously reported, epicutaneous sensitization using OVA resulted in increased antigen-specific Ig levels. Analysis of serum antibody levels in this study showed a similar increase following three sensitization periods. A dramatic decrease in total IgE levels, as well as OVA-specific IgE, IgG1 and IgG2a was observed in mice treated with Compound A at a dose of 10 mg kg1. A significant decrease was also noted in mice treated with just 0.1 mg kg1 of Compound A. As a positive control, dexamethasone delivered via PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/19825521 the i.p. route also reduced levels of total and OVA-specific IgE and OVA-specific IgG2a 8 CRTH2 blocks OVA-induced skin inflammation Fig. 3. Protein levels of IL-1b, IL-4 and MIP-1b in sensitized skin sections of mice treated with PBS/drug vehicle, OVA/drug vehicle, OVA/ Compound A and OVA/Dex. A 100 lg of protein from homogenized skin lysates was examined by ELISA. The columns represent the mean 6 SEM, n = 5 mice per treatment group. levels. Interestingly, dexamethasone treatment d