Modulation of the Immune Response

Abstract

Methods for identifying compounds that modulate the generation of regulatory T cells (Treg) in vivo and in vitro, i.e., compounds that act on the transcription factors that increase or decrease expression of Foxp3.

1 . A composition comprising a ligand that binds specifically to an aryl hydrocarbon receptor (AHR) transcription factor, linked to a biocompatible nanoparticle. 
     
     
         2 . The composition of  claim 1 , wherein the ligand is a small molecule that competes for binding to the AHR competitively with 2,3,7,8 tetrachlorodibenzo-p-dioxin (TCDD) and activates AHR-dependent signaling. 
     
     
         3 . The composition of  claim 1 , wherein the ligand is 2,3,7,8 tetrachlorodibenzo-p-dioxin (TCDD). 
     
     
         4 . The composition of  claim 1 , wherein the ligand is tryptamine (TA). 
     
     
         5 . The composition of  claim 1 , further comprising a monoamine oxidase inhibitor such as tranylcypromine. 
     
     
         6 . The composition of  claim 1 , wherein the ligand is 2-(1′H-indole-3′-carbonyl)-thiazole-4-carboxylic acid methyl ester (ITE). 
     
     
         7 . The composition of  claim 1 , wherein the ligand is 6 formylindolo[3,2 b]carbazole (FICZ). 
     
     
         8 . The composition of  claim 1 , further comprising an antibody that selectively binds to an antigen present on a T cell, a B cell, a dendritic cell, or a macrophage. 
     
     
         9 . The composition of  claim 8 , wherein the antibody is linked to the biocompatible nanoparticle. 
     
     
         10 . A method for increasing the number of CD4/CD25/Foxp3-expressing T regulatory (Treg) cells in a population of T cells, the method comprising:
 contacting the population of cells with a sufficient amount of a composition comprising one or more AHR ligands selected from the group consisting of 2,3,7,8 tetrachlorodibenzo-p-dioxin (TCDD), tryptamine (TA), and 2-(1′H-indole-3′-carbonyl)-thiazole-4-carboxylic acid methyl ester (ITE), wherein the ligand is linked to a biocompatible nanoparticle, and   optionally evaluating the presence and/or number of CD4/CD25/Foxp3-expressing cells in the population;   wherein the method results in an increase in the number and/or activity of regulatory T cells (Treg).   
     
     
         11 . The method of  claim 10 , wherein the population of T cells comprises naïve T cells or CD4+CD62 ligand+ T cells. 
     
     
         12 . The method of  claim 10 , further comprising administering the Treg cells to a subject suffering from an autoimmune disorder, in an amount sufficient to improve or ameliorate a symptom of the disorder. 
     
     
         13 . The method of  claim 10 , wherein the population of T cells is in a living mammalian subject. 
     
     
         14 . The method of  claim 13 , wherein the subject has an autoimmune disorder. 
     
     
         15 . The method of  claim 10 , wherein the autoimmune disorder is multiple sclerosis. 
     
     
         16 . The method of  claim 13 , comprising administering the one or more ligands orally. 
     
     
         17 . The method of  claim 13 , comprising administering the one or more ligands intravenously. 
     
     
         18 . A method of identifying a candidate compound that increases generation or activity of regulatory T cells (Treg), the method comprising:
 providing a cell expressing a reporter construct comprising a binding sequence for the Aryl Hyrocarbon Receptor (AHR) in a mammalian Foxp3 promoter sequence, wherein said binding sequence is operably linked to a reporter gene, for example a reporter gene selected from the group consisting of luciferase, green fluorescent protein, and variants thereof;   contacting the cell with a test compound; and   evaluating an effect of the test compound on expression of the reporter gene,   wherein a test compound that increases or decreases expression of the reporter gene is a candidate compound that modulates generation of Treg.   
     
     
         19 . The method of  claim 18 , further comprising measuring expression of the reporter construct in the presence of a known AHR ligand selected from the group consisting of 2,3,7,8 tetrachlorodibenzo-p-dioxin (TCDD), tryptamine (TA), and 2-(1′H-indole-3′-carbonyl)-thiazole-4-carboxylic acid methyl ester (ITE), or a compound that binds to the AHR competitively therewith; determining whether the candidate compound competes for binding to the AHR with the known compound; and selecting the candidate compound if it binds the AHR competitively with the known compound. 
     
     
         20 . A method of identifying a candidate compound that modulates generation of regulatory T cells (Treg), the method comprising:
 providing a living zebrafish;   contacting the zebrafish with a test compound;   evaluating an effect of the test compound on Foxp3 expression in the zebrafish,   wherein a test compound that increases or decreases expression of Fox-3 in the zebrafish is a candidate compound that modulates generation of Treg.   
     
     
         21 . The method of  claim 5 , wherein the zebrafish comprises a luciferase reporter construct encoding a human, murine or zebrafish Foxp3 gene.