Interleukin-1β induces the expression of HSP70, heme oxygenase and Mn-SOD in FACS-purified rat islet β-cells, but not in α-cells

The cytokine IL-1β has previously been demonstrated to induce the expression of the stress genes iNOS, hsp70, heme oxygenase and Mn-SOD in rat pancreatic islets in vitro. The aim of this study was to determine whether the IL-1β-induced effects are specific for the insulin producing β-cell, or whether other islet cells, such as the glucagon-producing α-cell, respond to IL-1β addition. Purified rat α- and β-cell suspensions were obtained by fluorescence-activated cell sorting and incubated with or without IL-1β (25 U/ml) for 24 h. The α- and β-cell contents of hsp70, heme oxygenase and Mn-SOD and medium nitrite levels were determined. It was found that IL-1β exposure induced the production of nitric oxide in β-cells, but not in α-cells. Moreover, the expression of hsp70, heme oxygenase and Mn-SOD was also induced in β-cells, but not in α-cells. There were no detectable levels of hsp70 in α-cells. It is concluded that the stress gene response following IL-1β exposure in markedly different in α- and β-cells. This finding may be of importance for the understanding of the autoimmune destruction of β-cells in insulin-dependent diabetes mellitus.