A small molecule CRTH2 antagonist inhibits FITC-induced allergic cutaneous inflammation

Abstract

A FITC-induced allergic contact hypersensitivity model was used to investigate the role that the prostaglandin D(2) receptor-chemoattractant receptor-homologous molecule expressed on T(h)2 cells (CRTH2) plays in modulating cutaneous inflammation. Our results show that inhibition of CRTH2, achieved via administration of a potent, small molecule antagonist, Compound A (Cmpd A), effectively blocked edema formation and greatly reduced the inflammatory infiltrate and skin pathology observed in drug vehicle-treated animals. Gene expression analysis revealed that Cmpd A administration down-regulated the transcription of a wide range of pro-inflammatory mediators. This correlated with decreases in cytokine and chemokine protein levels, notably IL-4, IL-1beta, tumor necrosis factor-alpha, transforming growth factor-beta, GRO-alpha, MIP-2 and thymic stromal lymphopoietin (TSLP) in FITC-challenged ears. The administration of an anti-TSLP-neutralizing antibody was only partially effective in lowering the FITC-induced inflammatory infiltrate and cytokine production compared with the CRTH2 antagonist. Taken together, these data suggest that blockade of CRTH2 inhibits multiple pathways leading to cutaneous inflammation in this model. This suggests that CRTH2 antagonism may be a viable route for therapeutic intervention in allergic skin diseases, such as atopic dermatitis.

CRTH2 is Critical to the Development of Colitis Induced by Dextran Sodium Sulfate (DSS)

“…Due to its specificity, we believe this compound is a useful tool to analyze the biology of CRTH2 in animal models of inflammation. Consistent with the role of CRTH2 in promoting allergic inflammation at barrier surface of the skin and lung [14,25,26], CRTH2 inhibitor suppressed the oxazolone-induced contact dermatitis when administered orally or topically by modulating the expression of not only the Th2 cytokine IL13 but also other pro-inflammatory cytokines including IFNγ, IL-17 A and IL-21. More importantly, Compound A also reduced the severity of DSS-induced colitis as revealed by improved percentage body weight change, inflammatory biomarker, serum haptoglobin as well as histopathology and cytokine gene/protein expression.…”

“…Additionally, CRTH2 has been implicated in the development of cutaneous inflammation as CRTH2 + CD4 + T cells and CRTH2 + eosinophils are increased in the blood of atopic dermatitis patients [13]. In mice, CRTH2 antagonists has been shown to effectively attenuate skin inflammation in various contact sensitivity models [14][15][16] including the oxazolone induced contact dermatitis model described in this report.…”

“…CHO-K1 cells expressing recombinant human CRTH2 (Euroscreen, Belgium) were harvested, washed twice in PBS, and re-suspended in PBS to a cell density of 2 million cells per mL. A dilution series of inhibitor concentrations was prepared in a solution containing 20 nM of [5,6,8,9,12,14, H]-PGD 2 (Perkin Elmer, Waltham, Massachusetts, 100-210 Ci/mmol stock) in PBS. The assay was initiated by transferring 50 mL of the compound dilution series and 50 uL of the re-suspended cells to a 96-well assay plate, for a final assay volume of 100 mL, and a final cell density of 100,000 cells per well.…”

“…Overall, results here are consistent with the previously published results suggesting that the CRTH2 pathway is critically involved in oxazolone-induced CHS. Compound A is efficacious in blocking the CRTH2 pathway and preventing skin inflammation [12,14].…”

Role of histamine H 4 receptor ligands in bleomycin-induced pulmonary fibrosis

“…In a model of dermal inflammation, pro-inflammatory cytokines, such as IL-4 and chemokines, were increased in ear tissue on fluorescein isothiocyanate (FITC) challenge, an effect significantly reduced with the treatment with H 4 R antagonists [45]. The administration of JNJ dose-dependently reduced the ear edema and the scratching response [46].…”