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Inactivation of the PLA 2 Activity of Prdx6 Ameliorates Sepsis‐Induced Acute Lung Injury
Author(s) -
VazquezMedina Jose Pablo,
Tao JianQin,
Patel Priyal,
Dodia Chandra,
Sorokina Elena,
Feinstein Sheldon I,
Chatterjee Shampa,
Fisher Aron B
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.694.4
Subject(s) - chemistry , hydrogen peroxide , microbiology and biotechnology , sepsis , superoxide , intracellular , reactive oxygen species , immunology , biochemistry , medicine , enzyme , biology
Prdx6 is a multi‐functional protein that expresses peroxidase, phospholipase A 2 (PLA 2 ) and LPC acyltransferase activities. While the three activities of Prdx6 contribute to either the scavenging of lipid hydroperoxides or to the repair of peroxidized membranes, the PLA 2 activity of Prdx6 (aiPLA 2 ) is also required for NOX2 activation in pulmonary microvascular cells (PMVECs), alveolar macrophages and polymorphonuclear neutrophils. During sepsis‐induced acute lung injury (ALI), NOX2 is activated generating superoxide radicals that contribute to vascular inflammation. To test whether inactivation of aiPLA 2 ameliorates sepsis‐induced ALI, we used a knock‐in mouse model that lacks aiPLA 2 activity due to a mutation of a key member of the PLA 2 catalytic triad (Prdx6‐D140A). Prdx6‐D140A mice treated IP with LPS (10 mg/Kg) exhibited increased survival rates compared to WT mice (75% vs 25% 4 days after LPS). Total nucleated cells in BALF, lung VCAM‐1 expression, and lung permeability increased significantly (p<0.05) after 24 h treatment with LPS in WT but not in Prdx6‐D140A mice. In PMVECs, LPS treatment (1 μg/mL for 8h) increased Prdx6 phosphorylation and aiPLA 2 activity by two‐fold (p<0.05). Furthermore, phosphorylated Prdx6 was localized at the plasma membrane after LPS treatment. LPS also increased extracellular hydrogen peroxide generation (Amplex Red oxidation) by 70% in WT but not in NOX2 null or Prdx6‐D140A PMVECs (p<0.05). Similarly, LPS increased intracellular hydrogen peroxide generation by 90% in WT PMVECs stably‐expressing the pHyPer‐Cyto sensor. Increased intracellular hydrogen peroxide generation was prevented by pre‐treatment with MJ33, a pharmacological inhibitor of aiPLA 2 . These results demonstrate that aiPLA 2 is needed for LPS‐induced, NOX2‐driven oxidant generation in PMVECs. Results also show that genetic inactivation of aiPLA 2 reduces LPS‐induced vascular inflammation, increased vascular permeability, and mortality in an animal model. Furthermore, these studies suggest that aiPLA 2 could be a target for prevention or treatment of sepsis‐induced ALI. Support or Funding Information Research funded by NHLBI L105509 and HL102016.