Endogenously produced itaconate negatively regulates innate-driven cytokine production and drives global ubiquitination in human macrophages
A wide variety of electrophilic derivatives of the Kreb's cycle-derived metabolite, itaconate, are immunomodulatory, yet these derivatives have overlapping and sometimes contradictory activities. Therefore, we generated a genetic system to interrogate the immunomodulatory functions of endogenously produced itaconate in human macrophages. Endogenous itaconate is driven by multiple innate signals restraining inflammatory cytokine production. Endogenous itaconate directly targets cysteine 13 in IRAK4 disrupting IRAK4 autophosphorylation and activation, drives the degradation of NF?B, and modulates global ubiquitination patterns. As a result, cells unable to make itaconate overproduce inflammatory cytokines such as TNFa, IL6, and IL-1ß in response to these innate activators. In contrast, the production of IFNß, downstream of LPS, requires the production of itaconate. These data demonstrate that itaconate is a critical arbiter of inflammatory cytokine production downstream of multiple innate signaling pathways laying the groundwork for the development of itaconate mimetics for the treatment of autoimmunity. Overall design: WT and IRG1 KO THP-s cells were differentiated with PMA for 72 hr. Cells were subsequently stimulated with LPS and IFNg for 6, 12, and 24 hr before RNA was collected and analyzed by RNA sequencing. Each condition has 3 replicates.