A novel low molecular weight inhibitor of dendritic cells and B cells blocks allergic inflammation

Rationale and Objective: During allergic lung inflammation dendritic cells (DCs) direct the generation and function of effector T-helper type 2 cells. T-helper type 2 cells not only orchestrate the inflammatory processes in the tissue by inducing the accumulation and activation of proinflammatory cells but also induce IgE production by B cells. Thus, inhibitors of DC function should have therapeutic benefits in patients with allergies. Methods and Measurements: VAF347, a novel low molecular weight immunomodulator, is described and acts as an antiinflarnmatory compound by a dual mode of action. Results: VAF347 inhibited the function of human monocyte-derived DCs to induce T-cell proliferation and cytokine production. Mechanistically, this effect may be due to reduced expression of CD86, HILA-DR, and interleukin 6 by DCs. In addition, the compound inhibited IgE synthesis in an isotype-specific fashion by human B lymphocytes. In a mouse model of antigen-induced eosinophilic inflammation, VAF347 blocked lung eosinophilia, mucus hyperplasia, and serum IgE levels, representing the hallmarks of allergic lung inflammation. The biological effects in vivo are most likely mediated by the immunoregulatory role of VAF347 on DCs because allergic lung inflammation was also inhibited in B-cell-cleficient mice. Conclusion: VAF347 represents a novel type of immunomodulator by affecting two major pathways in allergic airway pathogenesis: dendritic cell-mediated T-helper-cell activation and induction of IgE production by human B lymphocytes.