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Updated: Jun 23, 2026
Transfer of Manipulated Tumor-associated Neutrophils into Tumor-Bearing Mice to Study their Angiogenic Potential In Vivo
Published on: July 20, 2019
Myeloid-specific deletion of tumor suppressor PTEN augments neutrophil transendothelial migration during inflammation
Bara Sarraj1, Steffen Massberg, Yitang Li
1Department of Lab Medicine, Children's Hospital, and.
Abstract:
Phosphatidylinositol 3,4,5-trisphosphate (PIP(3)) is a second messenger that is involved in a number of cell activities including cell growth, proliferation, and motility. PIP(3) is produced by PI3K and regulated by PTEN (phosphatase and tensin homolog deleted on chromosome 10) and SHIP lipid phosphatases. Evidence from our experiments shows that enhanced PIP(3) production results in elevated neutrophil recruitment under inflammatory conditions. However, the mechanism of this elevation is not well understood. We used intravital video microscopy to investigate neutrophil recruitment in the cremaster venules of wild-type and PTEN knockout (KO) mice. Neutrophil transmigration was augmented in PTEN KO mice 4 h after TNF-alpha intrascrotal injection. PTEN KO neutrophils also showed significantly enhanced transmigration 2 h after MIP-2 intrascrotal injection, an effect that dramatically decreased when PI3K or Src kinase inhibitor treatments preceded MIP-2 stimulation. Similarly, fMLP superfusion of the cremaster muscle lead to enhanced emigration in PTEN KO mice. The observed elevation in neutrophil emigration was likely caused by increased speed of crawling, crossing the venular wall, and migrating through the muscular tissue in PTEN KO mice because the effect of PTEN depletion on neutrophil rolling or adhesion was minimal. Interestingly, chemoattractant-induced release of gelatinase and elastase was also elevated in PTEN null neutrophils, providing a potential mechanism for the enhanced neutrophil migration in the PTEN KO mice. Collectively, these results demonstrate that PTEN deletion in neutrophils enhances their invasivity and recruitment to inflamed sites more likely by raising the cell physical capability to cross the vascular and tissue barriers.
Insights
Phosphatase and tensin homolog (PTEN) deletion enhances neutrophil recruitment to inflamed tissues. This occurs by increasing neutrophil speed and invasivity, rather than adhesion or rolling, potentially via elevated enzyme release.
Area of Science:
- Cellular and Molecular Biology
- Immunology
- Physiology
Background:
- Phosphatidylinositol 3,4,5-trisphosphate (PIP(3)) is a critical second messenger regulating cell growth, proliferation, and motility.
- PI3K produces PIP(3), while PTEN (phosphatase and tensin homolog deleted on chromosome 10) and SHIP phosphatases regulate its levels.
- Enhanced PIP(3) signaling is linked to increased neutrophil recruitment during inflammation, but the underlying mechanisms remain unclear.
Purpose of the Study:
- To investigate the role of PTEN in regulating neutrophil recruitment and transmigration.
- To elucidate the cellular mechanisms by which PTEN deficiency impacts neutrophil behavior at inflammatory sites.
Main Methods:
- Intravital video microscopy was employed to visualize and quantify neutrophil recruitment in cremaster venules of wild-type and PTEN knockout (KO) mice.
- Neutrophil migration was assessed following stimulation with TNF-alpha, MIP-2, and fMLP.
- The effects of PI3K and Src kinase inhibitors on neutrophil transmigration were evaluated.
Main Results:
- PTEN KO mice exhibited significantly augmented neutrophil transmigration in response to TNF-alpha and MIP-2.
- PTEN-deficient neutrophils displayed enhanced crawling speed and invasivity across vascular and tissue barriers, with minimal changes in rolling or adhesion.
- Chemoattractant-induced release of gelatinase and elastase was elevated in PTEN null neutrophils, suggesting a role in enhanced migration.
Conclusions:
- PTEN deletion in neutrophils significantly enhances their recruitment to inflamed tissues.
- The enhanced neutrophil invasivity and migration are likely mediated by increased cellular motility and enzymatic activity, rather than altered adhesion.
- These findings highlight PTEN's crucial role in controlling neutrophil inflammatory responses and suggest PTEN deficiency can promote greater immune cell infiltration.
