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Updated: Jul 14, 2026
A Method for Generating Pulmonary Neutrophilia Using Aerosolized Lipopolysaccharide
Published on: December 15, 2014
Myeloid Poldip2 Contributes to the Development of Pulmonary Inflammation by Regulating Neutrophil Adhesion in a
Ziwei Ou1,2, Elena Dolmatova1, Rohan Mandavilli1
1Division of Cardiology Department of Medicine Emory University Atlanta GA.
Abstract:
Background Lung injury, a severe adverse outcome of lipopolysaccharide-induced acute respiratory distress syndrome, is attributed to excessive neutrophil recruitment and effector response. Poldip2 (polymerase δ-interacting protein 2) plays a critical role in regulating endothelial permeability and leukocyte recruitment in acute inflammation. Thus, we hypothesized that myeloid Poldip2 is involved in neutrophil recruitment to inflamed lungs. Methods and Results After characterizing myeloid-specific Poldip2 knockout mice, we showed that at 18 hours post-lipopolysaccharide injection, bronchoalveolar lavage from myeloid Poldip2-deficient mice contained fewer inflammatory cells (8 [4-16] versus 29 [12-57]×104/mL in wild-type mice) and a smaller percentage of neutrophils (30% [28%-34%] versus 38% [33%-41%] in wild-type mice), while the main chemoattractants for neutrophils remained unaffected. In vitro, Poldip2-deficient neutrophils responded as well as wild-type neutrophils to inflammatory stimuli with respect to neutrophil extracellular trap formation, reactive oxygen species production, and induction of cytokines. However, neutrophil adherence to a tumor necrosis factor-α stimulated endothelial monolayer was inhibited by Poldip2 depletion (225 [115-272] wild-type [myePoldip2+/+] versus 133 [62-178] myeloid-specific Poldip2 knockout [myePoldip2-/-] neutrophils) as was transmigration (1.7 [1.3-2.1] versus 1.1 [1.0-1.4] relative to baseline transmigration). To determine the underlying mechanism, we examined the surface expression of β2-integrin, its binding to soluble intercellular adhesion molecule 1, and Pyk2 phosphorylation. Surface expression of β2-integrins was not affected by Poldip2 deletion, whereas β2-integrins and Pyk2 were less activated in Poldip2-deficient neutrophils. Conclusions These results suggest that myeloid Poldip2 is involved in β2-integrin activation during the inflammatory response, which in turn mediates neutrophil-to-endothelium adhesion in lipopolysaccharide-induced acute respiratory distress syndrome.
Insights
Myeloid Poldip2 regulates neutrophil recruitment in lung injury by controlling beta-2 integrin activation. This finding is crucial for understanding acute respiratory distress syndrome and developing targeted therapies.
Area of Science:
- Immunology
- Cell Biology
- Pulmonary Medicine
Background:
- Acute respiratory distress syndrome (ARDS) involves lung injury driven by excessive neutrophil recruitment.
- Polymerase delta-interacting protein 2 (Poldip2) influences endothelial permeability and leukocyte recruitment.
- Myeloid Poldip2's role in neutrophil recruitment to inflamed lungs was investigated.
Purpose of the Study:
- To investigate the role of myeloid Poldip2 in neutrophil recruitment during lipopolysaccharide-induced lung injury.
- To elucidate the mechanisms by which Poldip2 affects neutrophil-endothelial interactions.
Main Methods:
- Characterization of myeloid-specific Poldip2 knockout mice.
- Analysis of bronchoalveolar lavage fluid for inflammatory cell counts.
- In vitro assessment of neutrophil functions including adherence and transmigration.
- Examination of beta-2 integrin surface expression, binding, and Pyk2 phosphorylation.
Main Results:
- Myeloid Poldip2 deficiency reduced inflammatory cell and neutrophil accumulation in LPS-induced lung injury.
- Poldip2-deficient neutrophils showed impaired adherence and transmigration across TNF-α-stimulated endothelial cells.
- Beta-2 integrin activation and Pyk2 phosphorylation were reduced in Poldip2-deficient neutrophils.
- Neutrophil extracellular trap formation, ROS production, and cytokine induction were unaffected by Poldip2 deficiency in vitro.
Conclusions:
- Myeloid Poldip2 is essential for regulating beta-2 integrin activation in neutrophils.
- Poldip2-mediated beta-2 integrin activation is critical for neutrophil adhesion to endothelium in ARDS.
- Targeting myeloid Poldip2 may offer a therapeutic strategy for ARDS.
