FASEB journal : official publication of the Federation of American Societies for Experimental Biology
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Protease-activated receptor-2 (PAR₂) is a G-protein coupled receptor (GPCR) associated with a variety of pathologies. However, the therapeutic potential of PAR₂ is limited by a lack of potent and specific ligands. Following proteolytic cleavage, PAR₂ is activated through a tethered ligand. ⋯ Moreover, STLs demonstrated significant improvement in potency in vivo, evoking mechanical allodynia with an EC₅₀ of 14.4 pmol. STLs failed to elicit responses in PAR2(-/-) cells at agonist concentrations of >300-fold their EC₅₀ values. Our results demonstrate that the STL approach is a powerful tool for increasing ligand potency at PAR₂ and represent opportunities for drug development at other protease activated receptors and across GPCRs.
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Idiopathic pulmonary fibrosis (IPF) is a chronic and progressive interstitial lung disease, wherein transforming growth factor β (TGF-β) and sphingosine-1-phosphate (S1P) contribute to the pathogenesis of fibrosis. However, the in vivo contribution of sphingosine kinase (SphK) in fibrotic processes has not been documented. Microarray analysis of blood mononuclear cells from patients with IPF and SphK1- or SphK2-knockdown mice and SphK inhibitor were used to assess the role of SphKs in fibrogenesis. ⋯ Knockdown of SphK1 or treatment with SphK inhibitor attenuated S1P generation and TGF-β secretion in a bleomycin-induced lung fibrosis mouse model that was accompanied by reduced phosphorylation of Smad2 and MAPKs in lung tissue. In vitro, bleomycin-induced expression of SphK1 in lung fibroblast was found to be TGF-β dependent. Taken together, these data indicate that SphK1 plays a critical role in the pathology of lung fibrosis and is a novel therapeutic target.
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The underlying mechanisms of itch are poorly understood. We have investigated a model involving the chemoattractant leukotriene B₄ (LTB₄) that is up-regulated in common skin diseases. Intradermal injection of LTB4 (0.1 nmol/site) into female CD1 mice induced significant scratching movements (used as an itch index) compared with vehicle-injected (0.1% bovine serum albumin-saline) mice. ⋯ Myeloperoxidase activity was also reduced by SB366791 (35%) and SOD (28%). TRPV1-KO mice showed impaired myeloperoxidase release, whereas TRPA1-KO mice exhibited diminished production of superoxide. This result provides novel evidence that TRPA1 and TRPV1 contribute to itch via distinct mechanisms.