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Chinese medicinal herbs reverse macrophage suppression induced by urological tumors
J R Rittenhouse1, P D Lui, B H Lau
1Departments of Urology School of Medicine, Loma Linda University, California 92350.
Abstract:
Tumors are known to produce factors suppressing macrophage function. In this study we demonstrated in vitro suppression of macrophage chemiluminescent oxidative burst associated with viable cells and cell-free extracts of two urological neoplasms--murine renal cell carcinoma (Renca) and murine bladder tumor (MBT). Suppression was reversed by extracts of two Chinese medicinal herbs, Astragalus membranaceus (AM) and Ligustrum lucidum (LL). Murine macrophage cell line J774 was incubated with either the viable tumor cells or the cell-free tumor extract for 18 hours at 37C and 5% CO2. Chemiluminescent oxidative burst as an indicator of macrophage function was triggered by adding zymosan A suspension containing luminol and assayed in an automated luminometer. Photon emission over time was counted and the results were expressed as integrated photon emission. Significant dose-related depression of oxidative burst occurred with either the viable tumor cells or the cell-free tumor extracts. Depression was partially or completely reversed by the presence of 50-100 micrograms./ml. of either the AM or the LL extract. AM and LL have previously been shown to modulate immune response. Data from this study suggest that they may also exert their antitumor activity via abolition of tumor-associated macrophage suppression.
Insights
Tumors suppress macrophage function, but extracts from Astragalus membranaceus and Ligustrum lucidum reversed this suppression in vitro. These findings suggest Chinese medicinal herbs may combat tumors by restoring macrophage activity.
Area of Science:
- Immunology
- Oncology
- Pharmacology
Background:
- Tumors often produce factors that inhibit macrophage immune functions.
- Macrophage dysfunction is implicated in tumor progression and immune evasion.
Purpose of the Study:
- To investigate the in vitro effect of urological neoplasms on macrophage oxidative burst.
- To determine if extracts from Astragalus membranaceus (AM) and Ligustrum lucidum (LL) can reverse tumor-induced macrophage suppression.
Main Methods:
- Murine macrophage cell line J774 was exposed to murine renal cell carcinoma (Renca) or murine bladder tumor (MBT) cells/extracts.
- Macrophage function was assessed by measuring the chemiluminescent oxidative burst triggered by zymosan A.
- The effect of AM and LL extracts on macrophage function was evaluated.
Main Results:
- Viable Renca and MBT cells, along with their cell-free extracts, significantly suppressed the macrophage oxidative burst.
- Addition of AM or LL extracts (50-100 µg/ml) partially or completely reversed this tumor-induced suppression.
- Suppression was dose-dependent on tumor cell exposure.
Conclusions:
- Urological neoplasms actively suppress macrophage oxidative burst in vitro.
- Astragalus membranaceus and Ligustrum lucidum extracts can restore suppressed macrophage function.
- These herbs may exert antitumor effects by counteracting tumor-associated macrophage suppression, potentially modulating immune responses against cancer.