DJ-1/PARK7 Impairs Bacterial Clearance in Sepsis.

RATIONALE: Effective and rapid bacterial clearance is a fundamental determinant of outcomes in sepsis. DJ-1 is a well-established reactive oxygen species (ROS) scavenger. OBJECTIVES: Because cellular ROS status is pivotal to inflammation and bacterial killing, we determined the role of DJ-1 in bacterial sepsis. METHODS: We used cell and murine models with gain- and loss-of-function experiments, plasma, and cells from patients with sepsis. MEASUREMENTS AND MAIN RESULTS: 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 p47phox, a critical component of the NADPH oxidase complex, disrupting the complex and facilitating Nox2 (gp91phox) 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. CONCLUSIONS: These novel findings reveal DJ-1 impairs optimal ROS production for bacterial killing with important implications for host survival in sepsis.

ATF3 protects pulmonary resident cells from acute and ventilator-induced lung injury by preventing Nrf2 degradation.

AIMS: Ventilator-induced lung injury (VILI) contributes to mortality in patients with acute respiratory distress syndrome, the most severe form of acute lung injury (ALI). Absence of activating transcription factor 3 (ATF3) confers susceptibility to ALI/VILI. To identify cell-specific ATF3-dependent mechanisms of susceptibility to ALI/VILI, we generated ATF3 chimera by adoptive bone marrow (BM) transfer and randomized to inhaled saline or lipopolysacharide (LPS) in the presence of mechanical ventilation (MV). Adenovirus vectors to silence or overexpress ATF3 were used in primary human bronchial epithelial cells and murine BM-derived macrophages from wild-type or ATF3-deficient mice. RESULTS: Absence of ATF3 in myeloid-derived cells caused increased pulmonary cellular infiltration. In contrast, absence of ATF3 in parenchymal cells resulted in loss of alveolar-capillary membrane integrity and increased exudative edema. ATF3-deficient macrophages were unable to limit the expression of pro-inflammatory mediators. Knockdown of ATF3 in resident cells resulted in decreased junctional protein expression and increased paracellular leak. ATF3 overexpression abrogated LPS induced membrane permeability. Despite release of ATF3-dependent Nrf2 transcriptional inhibition, mice that lacked ATF3 expression in resident cells had increased Nrf2 protein degradation. INNOVATION: In our model, in the absence of ATF3 in parenchymal cells increased Nrf2 degradation is the result of increased Keap-1 expression and loss of DJ-1 (Parkinson disease [autosomal recessive, early onset] 7), previously not known to play a role in lung injury. CONCLUSION: Results suggest that ATF3 confers protection to lung injury by preventing inflammatory cell recruitment and barrier disruption in a cell-specific manner, opening novel opportunities for cell specific therapy for ALI/VILI.