Jian Zhao1,2, Qiang Zhao3, Peng Ning2, Kai Shang2, Cong Liu2, Mei Ni2, Chunpu Li2, Kaigang Zhang2, Chunzheng Gao1. 1. Department of Orthopedics, The Second Hospital of Shandong University, Jinan. 2. Department of Orthopedics, Taian Central Hospital, Taian. 3. Department of Orthopedics, The No.1 People's Hospital of Jining, Jining, Shandong, People's Republic of China.
Abstract
OBJECTIVE: Granulocyte colony-stimulating factor (G-CSF) is the critical regulator of the proliferation, differentiation, and survival of granulocytes. Recently, it has been shown that G-CSF can adversely affect bone health in both animal models and patients. Here, the authors aimed to investigate whether G-CSF could inhibit the growth of osteoblasts and osteocytes by regulating nitric oxide. METHODS: The C57BL/6 mice were divided into the control group, G-CSF treatment group and recovery group (G-CSF+L-NAME). The morphology of femurs was assessed by histology and immunohistochemistry. The expression of apoptosis-related molecules in femurs was detected by immunohistochemistry and quantitative RT-PCR, respectively. To examine if neutrophil-secreted factors can induce apoptosis in osteoblasts, Gr1-positive (Gr1+) neutrophils from the bone marrow of wild-type mice were sorted and co-cultured with MC3T3 pre-osteoblasts for 2 days. RESULTS: The number of osteoblasts and newly embedding osteocytes significantly decreased and markers related to osteoblasts and osteocytes were downregulated in the G-CSF treatment compared to the control group. Moreover, G-CSF treatment did not change proliferation markers but induced apoptosis in osteoblast-lineage cells. The combined treatment of mice with G-CSF and a nitric oxide inhibitor partially restored the number of osteoblasts and osteocyte parameters. CONCLUSIONS: The G-CSF can inhibit osteoblasts and osteocytes by upregulating nitric oxide.
OBJECTIVE:Granulocyte colony-stimulating factor (G-CSF) is the critical regulator of the proliferation, differentiation, and survival of granulocytes. Recently, it has been shown that G-CSF can adversely affect bone health in both animal models and patients. Here, the authors aimed to investigate whether G-CSF could inhibit the growth of osteoblasts and osteocytes by regulating nitric oxide. METHODS: The C57BL/6 mice were divided into the control group, G-CSF treatment group and recovery group (G-CSF+L-NAME). The morphology of femurs was assessed by histology and immunohistochemistry. The expression of apoptosis-related molecules in femurs was detected by immunohistochemistry and quantitative RT-PCR, respectively. To examine if neutrophil-secreted factors can induce apoptosis in osteoblasts, Gr1-positive (Gr1+) neutrophils from the bone marrow of wild-type mice were sorted and co-cultured with MC3T3 pre-osteoblasts for 2 days. RESULTS: The number of osteoblasts and newly embedding osteocytes significantly decreased and markers related to osteoblasts and osteocytes were downregulated in the G-CSF treatment compared to the control group. Moreover, G-CSF treatment did not change proliferation markers but induced apoptosis in osteoblast-lineage cells. The combined treatment of mice with G-CSF and a nitric oxide inhibitor partially restored the number of osteoblasts and osteocyte parameters. CONCLUSIONS: The G-CSF can inhibit osteoblasts and osteocytes by upregulating nitric oxide.