Autoimmunity-inducing metals (Hg, Au and Ag) modulate mast cell signaling, function and survival

The three heavy metals, mercury, gold and silver commonly and specifically induce aberrant immunological responses leading to autoimmune disorders in genetically susceptible animals and humans. The disorders are characterized by autoantibody production, increases in serum IgG and IgE, polyclonal activation of B and T lymphocytes and renal immune complex deposition and glomerulonephritis. Mast cells play key roles in allergic and inflammatory reactions. A growing body of evidence suggests that mast cells are key players in innate and adaptive immunity and involved in autoimmune diseases. Mast cells are also direct targets for autoimmunity-inducing metals both in vitro and in vivo and play a role in the development of metal-induced autoimmune disorders. The three metals specifically modulate mast cell function, including degranulation and secretion of arachidonic acid metabolites and cytokines such as interleukin-4. Divergent signaling components, including mitogen-activated protein kinase activation, reactive oxygen and nitric oxide generation and Ca2+ influx are modulated by the metals. Furthermore, the metals have considerable impacts on mast cell survival, which also species seems to be involved in the development of metal-induced autoimmune disorders. In this review, we provide an overview of recent advances in our understanding of the impacts of the three metals on mast cell signaling, function and survival and their possible roles in the pathologies of metal-induced autoimmunity.