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Harvesting Murine Alveolar Macrophages and Evaluating Cellular Activation Induced by Polyanhydride Nanoparticles
Published on: June 8, 2012
Impact of microparticles released during murine systemic inflammation on macrophage activity and reactive nitrogen
Weronika Ortmann1, Anna Such1,2, Elzbieta Kolaczkowska3
1Laboratory of Experimental Hematology, Institute of Zoology and Biomedical Research, Jagiellonian University, Gronostajowa 9 Street, 30-387, Krakow, Poland.
Abstract:
Microparticles (MPs) packaged with numerous bioactive molecules are essential vehicles in cellular communication in various pathological conditions, including systemic inflammation, Whereas MPs are studied mostly upon isolation, their detection in vivo is limited. Impact of MPs might depend on target cell type and cargo they carry; thus herein, we aimed at verifying MPs' impact on macrophages. Unlike neutrophils, monocytes/macrophages are rather inactive during sepsis, and we hypothesized this might be at least partially controlled by MPs. For the above reasons, we focused on the detection of MPs with intravital microscopy (IVM) and report the presence of putative neutrophil-derived MPs in the vasculature of cremaster muscle of endotoxemic mice. Subsequently, we characterized MPs isolated not only from their blood but also from the peritoneal cavity and observed differences in their size, concentration, and cargo. Such MPs were then used to study their impact on RAW 264.7 macrophage cell line performance (cell viability/activity, cytokines, oxygen, and nitrogen reactive species). Addition of MPs to macrophages with or without co-stimulation with lipopolysaccharide did not affect respiratory burst, somewhat decreased mitochondrial activity but increased inducible nitric oxide synthase (iNOS) expression, and NO production especially in case of plasma-derived MPs. The latter MPs carried more iNOS-controlling ceruloplasmin than those discharged into the peritoneal cavity. We conclude that MPs can be detected in vivo with IVM and their cellular origin identified. They are heterogeneous in nature depending on the site of their release. Consequently, microparticles released during systemic inflammation to various body compartments differentially affect macrophages.
Insights
Systemic inflammation releases microparticles (MPs) that affect macrophage activity. Intravital microscopy detected neutrophil-derived MPs in vivo, showing MPs from different body sites differentially impact macrophage function.
Area of Science:
- Cellular biology
- Immunology
- Biomedical engineering
Background:
- Microparticles (MPs) are crucial for cell communication, especially during systemic inflammation.
- In vivo detection of MPs is limited, hindering understanding of their pathological roles.
- Macrophages are less active during sepsis, potentially due to MP influence.
Purpose of the Study:
- To detect MPs in vivo using intravital microscopy (IVM).
- To characterize MPs from different body compartments (blood, peritoneal cavity).
- To investigate the impact of MPs on macrophage function.
Main Methods:
- Intravital microscopy (IVM) for in vivo MP detection in endotoxemic mice.
- Isolation and characterization of MPs from blood and peritoneal fluid.
- Assessing MP effects on macrophage viability, activity, cytokine production, and reactive species.
Main Results:
- Neutrophil-derived MPs were detected in the vasculature of endotoxemic mice.
- MPs from blood and peritoneal cavity showed variations in size, concentration, and cargo.
- Plasma-derived MPs increased inducible nitric oxide synthase (iNOS) expression and nitric oxide (NO) production in macrophages.
Conclusions:
- MPs can be detected and their cellular origin identified in vivo using IVM.
- MPs exhibit heterogeneity based on their release site during systemic inflammation.
- MPs released into different body compartments differentially modulate macrophage responses.
