Protocol:
High-throughput screening was performed at Indiana University screening facility (Indiana University, Indianapolis, IN).
In summary, a mixture of ST2 and IL-33 was prepared by adding 0.30 microL of 14.1 microM recombinant human ST2-Fc Chimera and 0.30 microL of 55.25 biotinylated recombinant human IL-33 to 1.4 mL of assay buffer. In the HTS, each well of a 384-well Proxi-plate was first blocked by 100 microL of assay buffer for 1 h at room temperature. After removing the blocking buffer, 20 microL of ST2/IL-33 mixture was pipetted into each well and incubated at room temperature for 1 h followed by addition of compounds at 17 microM (0.8 microL) to each well and incubated at room temperature for 1 h. Ten microliters of 60 microg/mL anti-6xHis-conjugated AlphaLISA acceptor beads were added to each well and incubated at room temperature for 1 h before addition of 10 microL of 60 microg/mL of streptavidin-labeled AlphaLISA donor beads for incubation at room temperature for 30 min. Incubation of acceptor and receptor beads was conducted in darkness. The well with 3 nM ST2 alone was used as a negative control, whereas the ST2/IL-33 mixture with a human ST2 antibody added at 0.45 ng/microL was used as the positive control. Plates were read using the Envision Plate Reader. The buffer used in the assay contains 14.37 mL PBS, 30 microL Tween 20, and 600 microL of 5% bovine serum albumin in PBS.
Comment:
PubChem active indicates >= 30% inhibition of ST2/IL-33 at 17 uM of the compound. Inconclusive: >=10% and < 30% inhibition.