Methods for identifying compounds that inhibit CD38 activity
The present invention relates to methods for modulating the migratory activity of cells expressing CD38 for the treatment of disorders including, but not limited to, inflammation, ischemia, asthma, autoimmune disease, diabetes, arthritis, allergies, infection with pathogenic organisms and transplant rejection. Such cells include, for example, neutrophils, lymphocytes, eosinophils, macrophages and dentritic cells. The invention further relates to drug screening assays designed to identify compounds that modulate the ADP-ribosyl cyclase activity of CD38 and the use of such compounds in the treatment of disorders involving CD38 modulated cell migration. The invention is based on the discovery that CD38 ADP-ribosyl cyclase activity is required for chemotaxis. Furthermore, the invention relates to methods for identifying compounds that modulate the enzyme activity of the S. mansoni CD38 homologue and using those compounds in the treatment of pathologic disorders caused by helminth infection. This is based on the discovery that helminths such as S. mansoni express CD38 homologues.
1. A method for identifying a compound that inhibits CD38 enzyme activity comprising (i) contacting a cell expressing CD38 and a chemoattractant receptor with a test compound in the presence of a chemoattractant and substrate and measuring the level of CD38 activity; (ii) in a separate experiment, contacting a cell expressing CD38 and a chemoattractant receptor with a vehicle control in the presence of a chemoattractant and substrate and measuring the level of CD38 activity where the conditions are essentially the same as in part (i); and then (iii) comparing the level of CD38 activity measured in part (i) with the level of CD38 activity in part (ii), wherein a decrease in the level of CD38 activity in the presence of the test compound indicates that the test compound is a CD38 inhibitor.
2. The method of claim 1 wherein CD38 mediated cell migration is measured.
3. The method of claim 1 , wherein the CD38 enzyme activity is selected from the group consisting of NAD + glycohydrolase activity, ADP-ribosyl cyclase activity, and transglycosidation activity.
4. The method of claim 3 , wherein enzyme activity is measured by monitoring the rate of formation of nicotinamide, ADP-ribose (ADPR), cyclic-ADPR (cADPR), or nicotinic acid adenine dinucleotide phosphate (NAADP).
5. The method of claim 1 , wherein the chemoattractant is selected from the group consisting of fMet-Leu-Phe (fMLP), eotaxin, growth-regulated oncogene-1 (GRO-1), interferon-gamma inducible protein-10 kDa (IP-10), stromal cell-derived factor-1 (SDF-1), B lymphocyte chemoattractant (BLC), chemokine ligand-5 (CCL5; Rantes), macrophage-inflammatory protein-1A (MIP-1A), monocyte chemoattractant protein-3 (MCP-3), macrophage-inflammatory protein-3a (MIP3a), interleukin-8 (IL-8), CLS, macrophage-inflammatory protein-3beta (MIP3β; ELC), lymphotactin, platelet-activating factor (PAF), leukotriene B4 (Ltb4), complement c5a, and histamine.