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Nitric oxide is important for mouse beta-cell line killing by peritoneal exudate cells obtained from cyclophosphamide
1Department of Internal Medicine, Keio University, School of Medicine, Tokyo, Japan.
Abstract:
Macrophages from recent onset non-obese diabetic (NOD) mice showed cytotoxicity against the NOD mouse derived beta-cell line, MIN6N-9a. In this report, we examined whether nitric oxide is associated with beta-cell destruction. Peritoneal exudate cells (PEC), obtained from cyclophosphamide treated NOD mice showed higher cytotoxicity against MIN6N-9a compared to PECs from saline injected NOD mice (P < 0.01). This effect was suppressed in cells incubated with 0.5 mmol/l NG-methyl-L-arginine, a nitric oxide synthase inhibitor (P < 0.001). In addition, the nitrite concentration of the co-culture medium, as an index of nitric oxide production, increased in MIN6N-9a cells co-cultured with peritoneal exudate cells from cyclophosphamide injected NOD mice but not in co-culture with saline injected NOD mice (P < 0.05). Thus, nitric oxide plays an important role in beta-cell line destruction of macrophages obtained from NOD mice.
Insights
Nitric oxide from macrophages contributes to beta-cell destruction in non-obese diabetic (NOD) mice. Inhibiting nitric oxide synthase reduced this cytotoxicity, indicating its key role in the disease process.
Area of Science:
- Immunology
- Endocrinology
- Diabetes Research
Background:
- Macrophages are implicated in autoimmune diabetes.
- Non-obese diabetic (NOD) mice are a model for type 1 diabetes.
- Beta-cell destruction is a hallmark of diabetes.
Purpose of the Study:
- To investigate the role of nitric oxide in macrophage-mediated beta-cell destruction.
- To determine if nitric oxide synthase inhibition affects beta-cell cytotoxicity in NOD mice.
Main Methods:
- Co-culture of MIN6N-9a beta-cells with peritoneal exudate cells (PECs) from NOD mice.
- Treatment of PECs with cyclophosphamide or saline.
- Inhibition of nitric oxide synthase using NG-methyl-L-arginine.
- Measurement of nitrite concentration in co-culture medium.
Main Results:
- PECs from cyclophosphamide-treated NOD mice exhibited enhanced cytotoxicity against MIN6N-9a cells.
- Nitric oxide synthase inhibition significantly suppressed this cytotoxic effect.
- Increased nitrite levels were observed in co-cultures with PECs from cyclophosphamide-treated NOD mice.
Conclusions:
- Nitric oxide plays a critical role in the destruction of beta-cell lines by macrophages from NOD mice.
- Targeting nitric oxide production may be a therapeutic strategy for type 1 diabetes.