Nerve growth factor, mast cells and arthritis

Nerve growth factor is a well-characterized neurotrophic protein required for the survival and differentiation of a variety of neuronal cell types both in the peripheral and central nervous systems. Recent studies indicate that nerve growth factor also plays a role in cells originating in the immune system, since it is synthesized by cells of immune system lineage and its level increases during inflammatory responses. Moreover, it has been shown that cytokines such as interleukin-1β and tumor necrosis factor-α are potent inducers of nerve growth factor secretion. These studies were recently confirmed and extended by demonstrating that cells normally present in inflammatory tissues, such as mast cells and lymphocytes, express nerve growth factor receptors and are receptive to the action of nerve growth factor. The aim of the present review is to outline the current understanding of mast cells and nerve growth factor in autoimmune diseases and particularly in arthritis.