NK cell dysfunction and interferon-γ production underlie autoinflammation in mevalonate kinase deficiency.

Prenylopathies such as mevalonate kinase deficiency (MKD) are an emerging family of monogenic autoinflammatory diseases with an underlying defect in isoprenoid lipid synthesis and protein prenylation. The mechanisms linking defective protein prenylation to systemic inflammation remain unclear. We revealed that mice and humans with MKD had significant decreases in the frequency of mature natural killer (NK) cells, impaired trafficking of cytolytic granules, reduced cytotoxic activity, and increased production of the cytokine interferon γ (IFN-γ). Mice with MKD failed to clear murine cytomegalovirus (MCMV) infections and had elevated serum IFN-γ and inflammatory pathology, likely the result of decreased and dysregulated cytotoxic cells. Finally, we describe the beneficial effect of cytokine signaling blockade with a Janus kinase (JAK) inhibitor in an infant with severe MKD. Together, these findings reveal a fundamental role for dysregulated cytotoxic cells and IFN-γ production in MKD and likely other prenylopathies. Importantly, this work provides a rationale for the use of JAK inhibitors in the treatment of MKD.