Chemokine regulation in response to beryllium exposure in human peripheral blood mononuclear and dendritic cells

Exposure to beryllium (Be) induces a delayed-type hypersensitivity immune reaction in the lungs of susceptible individuals, which leads to the onset of Be sensitivity and Chronic Beryllium Disease (CBD). Although some mechanistic aspects of CBD have begun to be characterized, very little is known about the molecular mechanisms by which Be activates the host immune response. To gain insight into the cellular response to Be exposure, we have performed global microarray analysis using a mixture of peripheral blood mononuclear and dendritic cells (PBMC/DCs) from a non-CBD source to identify genes that are specifically upregulated in response to BeSO4 stimulation, compared to a control metal salt, Al2(SO4)3. We identified a number of upregulated immunomodulatory genes, including several chemokines in the MIP-1 and GRO families. Using PBMC/DCs from three different donors, we demonstrate that BeSO4 stimulation generally exhibits an increased rate of both chemokine mRNA transcription and release compared to Al2(SO4)3 exposure, although variations among the individual donors do exist. We show that MIP-1α and MIP-1β neutralizing antibodies can partially inhibit the ability of BeSO4 to stimulate cell migration of PBMC/DCs in vitro. Finally, incubation of PBMC/DCs with BeSO4 altered the binding of the transcription factor RUNX to the MIP-1α promoter consensus sequence, indicating that Be can regulate chemokine gene activation. Taken together, these results suggest a model in which Be stimulation of PBMC/DCs can modulate the expression and release of different chemokines, leading to the migration of lymphocytes to the lung and the formation of a localized environment for development of Be disease in susceptible individuals.