Aconitate decarboxylase 1 is a mediator of polymicrobial sepsis

Sepsis is a challenging clinical syndrome caused by a dysregulated host response to infection. Here, we identified an unexpected proseptic activity of aconitate decarboxylase 1 (ACOD1) in monocytes and macrophages. Previous studies have suggested that ACOD1, also known as immune-responsive gene 1, is an immunometabolic regulator that favors itaconate production to inhibit bacterial lipopolysaccharide-induced innate immunity. We used next-generation sequencing of lipopolysaccharide-activated THP1 cells to demonstrate that ACOD1 accumulation confers a robust proinflammation response by activating a cytokine storm, predominantly through the tumor necrosis factor signaling pathway. We further revealed that the phosphorylation of cyclin-dependent kinase 2 (CDK2) on threonine-160 mediates the activation of mitogen-activated protein kinase 8 through receptor for activated C kinase 1, leading to JUN-dependent transcription of ACOD1 in human and mouse macrophages or monocytes. Genetic deletion of CDK2 or ACOD1 in myeloid cells, or the administration of the CDK inhibitor dinaciclib, protected mice against polymicrobial sepsis and was associated with improved survival and decreased cytokine storm. The expression of the CDK2-ACOD1 axis also correlated with severity of illness in a cohort of 40 patients with bacterial sepsis. Thus, our findings provide evidence for a previously unrecognized function of ACOD1 in innate immunity and suggest it as a potential therapeutic target for the treatment of sepsis.