DJ-1/PARK7 Impairs Bacterial Clearance in Sepsis

Effective and rapid bacterial clearance is a fundamental determinant of outcomes in sepsis. DJ-1 is a well-established reactive oxygen species (ROS) scavenger.

Because cellular ROS status is pivotal to inflammation and bacterial killing, we determined the role of DJ-1 in bacterial sepsis.

We used cell and murine models with gain- and loss-of-function experiments, plasma, and cells from patients with sepsis.

Stimulation of bone marrow-derived macrophages (BMMs) with endotoxin resulted in increased DJ-1 mRNA and protein expression. Cellular and mitochondrial ROS was increased in DJ-1-deficient (^-/-) BMMs compared with wild-type. In a clinically relevant model of polymicrobial sepsis (cecal ligation and puncture), DJ-1^-/- mice had improved survival and bacterial clearance. DJ-1^-/- macrophages exhibited enhanced phagocytosis and bactericidal activity in vitro, and adoptive transfer of DJ-1^-/- bone marrow-derived mononuclear cells rescued wild-type mice from cecal ligation and puncture-induced mortality. In stimulated BMMs, DJ-1 inhibited ROS production by binding to p47^phox, a critical component of the NADPH oxidase complex, disrupting the complex and facilitating Nox2 (gp91^phox) ubiquitination and degradation. Knocking down DJ-1 (siRNA) in THP-1 (human monocytic cell line) and polymorphonuclear cells from patients with sepsis enhanced bacterial killing and respiratory burst. DJ-1 protein levels were elevated in plasma from patients with sepsis. Higher levels of circulating DJ-1 were associated with increased organ failure and death.

These novel findings reveal DJ-1 impairs optimal ROS production for bacterial killing with important implications for host survival in sepsis.