Regulation Of IL-12 and IL-23 Production

National Institute Of Allergy And Infectious Diseases

Investigators

Linked publications & trials

Abstract

The broad purpose of this work is to further understand how microorganisms and vaccine adjuvants via their interaction with antigen presenting cells, such as macrophages and dendritic cells, affect the generation of T cell mediated immune responses via their ability to regulate the production of critical cytokines, such as IL-12 and IL-10, and type-1 interferons. Over the past year, we have focused on the genetic determinants for the regulation of cytokine production in mouse models of colitis. WE have also developed a new model of autoimmune eye disease that is mediated by similar genetic determinants as colitis induction. We have also been exploring ways to exploit signaling pathways that negatively regulate IL-12 and IL-23 production for the suppression of autoimmune disease. Several years ago we identified that signaling though another surface receptor, complement-receptor 3 (CD3,CD11b/CD18, Mac-1) inhibits IL-12 but not IL-10 production by human monocytes, and that antibodies to CR3 could be used to suppress IL-12 production in vitro. This has implications for understanding how pathogens that use CR3 as an receptor for entry into cells like monocytes and macrophages, have explited this pathway by preventing adequate IL-12 and Th1 responses necessary for their rapid erradication. In addition, they suggested that anti-CR3 may be used to inhibit abnormal inflammatory diseases. Preveiously we evaluated the ability of antibodies to CR3 to treat murine models of colitis and skin inflammation. We determined that anti-CR3 could be used effectively to treat inflammatory colitis and psorisiform dermatitis, indicating a possible novel approach to treatment of inflammatory bowel disease and psoriasis in humans. Over the past year, we have begun testing anti-CR3, as well as anti-IL-12p40 to treat a novel model of autoimmune keratoconjuctivitis that is similar to what occurs in dry-eye disease in humans. In other studies we previously identified tha ability of proteins that signal via 7-transmembrane domain G=protein coupled receptors to inhibit IL-12 and IL-23 production. These include chemoattractant/chemokine receptors, such as receptors for complement receptor C5a, the bavteria-derived peptide f-met-leu-phem and the and chemokine CCR2 acting via Gi-protein-coupled receptors and the intestinal bactrial toxins, cholera toxin and heat-labile toxin from E.coli acting via Gs-protein-coupled receptors. Futhermore we identified the signaling pathway mediating the suppression by C5a and FPR. These receptors act by signing via PI3K and AKT. We have now studied in detail the pathway that mediates regulation of IL-12 by cholera toxin and other Gs-protein signals that induce cAMP, wuch as beta 2 adrenergic agonists, prostaglandin E2, endocannabinoids, and ATP. This pathway results in innhibiton of the function of an intracellular transcription factor IRF8, also called ICSBP, which is essential for the induction of IL-12 by its requirement to be included in a transcriptional complex on the IL-12p40 promoter. Gs-signaling results in the inability of IRF8 to interact with IRF1 another required factor, which results in the lack of complex formation and thus the inability to transcribe the IL-12p40 gene.