Lack of isoprenoid products raises ex vivo interleukin‐1β secretion in hyperimmunoglobulinemia D and periodic fever syndrome

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Abstract
Objective To investigate whether the increased interleukin-1β (IL-1β) secretion in hyperimmunoglobulinemia D and periodic fever syndrome is due to the accumulation of mevalonate kinase (MK), the substrate of the deficient enzyme, or the lack of its products, the isoprenoid compounds. Methods The effects of lovastatin and farnesol (FOH), geranylgeraniol (GGOH), and mevalonate on peripheral blood mononuclear cells (PBMCs) from 8 patients with MK deficiency and from 13 controls were studied. Lovastatin inhibits isoprenoid biosynthesis by reducing the production of mevalonate. FOH and GGOH restore isoprenoid biosynthesis downstream from MK. Culture supernatants were collected for cytokine analysis 48 hours after stimulation with monoclonal antibodies against CD2 + CD28. Results Lovastatin induced a 15-fold rise in IL-1β secretion by normal anti–CD2 + CD28–stimulated cells (P < 0.001). This effect could be countered by mevalonate and, to a lesser extent, by FOH and GGOH. In the absence of lovastatin, mevalonate did not change IL-1β secretion. Stimulated MK-deficient cells secreted 9-fold more IL-1β than control PBMCs (P < 0.005), rising 2.4-fold in the presence of lovastatin. The effect of lovastatin on IL-1β secretion was reduced by mevalonate, FOH, and GGOH. Isoprenoid biosynthesis in PBMCs from patients was impaired due to the endogenous MK deficiency. Bypassing this defect with FOH, in the absence of lovastatin, led to a 62% reduction (P < 0.02) in IL-1β secretion by these cells. Conclusion In this model, shortage of isoprenoid end products contributes to increased IL-1β secretion by MK-deficient PBMCs, whereas excess mevalonate does not.