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DUSP3 is a small dual-specificity protein phosphatase with an unknown physiological function. We report that DUSP3 is strongly expressed in human and mouse monocytes and macrophages, and that its deficiency in mice promotes tolerance to LPS-induced endotoxin shock and to polymicrobial septic shock after cecal ligation and puncture. By using adoptive transfer experiments, we demonstrate that resistance to endotoxin is macrophage dependent and transferable, and that this protection is associated with a striking increase of M2-like macrophages in DUSP3−/− mice in both the LPS and cecal ligation and puncture models. We show that the altered response of DUSP3−/− mice to sepsis is reflected in decreased TNF production and impaired ERK1/2 activation. Our results demonstrate that DUSP3 plays a key and nonredundant role as a regulator of innate immune responses by mechanisms involving the control of ERK1/2 activation, TNF secretion, and macrophage polarization.

We report the generation of dual-specificity phosphatase 3 (DUSP3) deficient mice. These mice develop normally and do not exhibit any spontaneous phenotype. However, VHR-/- females, but not males, are resistant to LPS- and to polymicrobial infection-induced septic shock. After LPS injection, while VHR-/- males and VHR+/+ mice of both genders, displayed an increased serum levels of TNF-α and IFNγ, the levels of these cytokines remained significantly low in the VHR-/- females. In vitro experiments using peritoneal macrophages showed the same results suggesting that the systemic cytokines profiles observed are macrophages-dependent. Adoptive transfer of VHR-/- females bone marrow to irradiated VHR+/+ female mice, but not to VHR-/- or VHR+/+ males, protected them from death after administration of LPS. Interestingly, VHR-/- females were sensitive to TNF-α- induced lethality. We also report that the decrease of TNF-α production observed in VHR-/- female’s macrophages after LPS activation was associated with a decreased ERK1/2, but not MEK1/2, activation. Interestingly, pervanadate (PTP pan inhibitor) treatment prior to LPS activation restored ERK1/2 activation in the VHR-deficient macrophages, suggesting that VHR is targeting one of the ERK1/2 PTPs or DUSPs. These results, together with our observation that DUSP3 is the most highly expressed phosphatase in macrophages, suggest a key non-redundant role of VHR as positive regulator of TNF-α in innate immune response in females.