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Macrophage infiltration and heme oxygenase-1 expression correlate with angiogenesis in human gliomas
1Department of Biochemistry, Kyushu University School of Medicine, Maidashi, Fukuoka, Japan. nishie@biochem1.kyushu-u.ac.jp
Abstract:
Macrophages are key participants in angiogenesis. In this study on human brain tumors, we first investigated whether macrophage infiltration is associated with angiogenesis and malignant histological appearance. Immunostaining of macrophages and small vessels in resected glioma specimens indicated that numbers of infiltrating macrophages and small vessel density were higher in glioblastomas than in astrocytomas or anaplastic astrocytomas. Macrophage infiltration was closely correlated with vascular density in human gliomas. Heme oxygenase-1 (HO-1), which is the rate-limiting enzyme in heme catabolism, was also associated with activated macrophages. Expression of mRNA encoding HO-1 was correlated with macrophage infiltration and vascular density in human glioma samples. Infiltrating macrophages were positively stained with anti-HO-1 antibody by immunohistochemical analysis, and in situ hybridization for HO-1 indicated that HO-1 was expressed in infiltrating macrophages in gliomas. HO-1 gene may be a useful marker for macrophage infiltration as well as neovascularization in human gliomas.
Insights
Macrophages are key in angiogenesis and brain tumor growth. This study found macrophage infiltration correlates with higher vascular density and malignancy in human gliomas, suggesting Heme oxygenase-1 (HO-1) as a potential marker.
Area of Science:
- Oncology
- Immunology
- Neuroscience
Background:
- Macrophages play a crucial role in angiogenesis, the formation of new blood vessels.
- Understanding the relationship between macrophages, angiogenesis, and tumor malignancy is vital for developing effective brain tumor therapies.
Purpose of the Study:
- To investigate the association between macrophage infiltration, angiogenesis, and histological malignancy in human gliomas.
- To explore the role of Heme oxygenase-1 (HO-1) in activated macrophages within gliomas.
Main Methods:
- Immunohistochemical staining of macrophages and small vessels in glioma specimens.
- Correlation analysis between macrophage infiltration, vascular density, and HO-1 expression.
- In situ hybridization to detect HO-1 expression in infiltrating macrophages.
Main Results:
- Higher macrophage infiltration and vascular density were observed in glioblastomas compared to lower-grade astrocytomas.
- Macrophage infiltration strongly correlated with increased vascular density in human gliomas.
- Heme oxygenase-1 (HO-1) expression was associated with activated macrophages and correlated with macrophage infiltration and vascular density.
Conclusions:
- Macrophage infiltration is closely linked to angiogenesis and malignant progression in human gliomas.
- The Heme oxygenase-1 (HO-1) gene shows promise as a marker for both macrophage infiltration and neovascularization in gliomas.