Chronic alcohol ingestion induces osteoclastogenesis and bone loss through IL-6 in mice
Jinlu Dai, Dinlii Lin, Jian Zhang, Paula Habib, Peter Smith, Jill Murtha, Zheng Fu, Zhi Yao, Yinghua Qi, Evan T. Keller
Jinlu Dai, Dinlii Lin, Jian Zhang, Paula Habib, Peter Smith, Jill Murtha, Zheng Fu, Zhi Yao, Yinghua Qi, Evan T. Keller
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Article

Chronic alcohol ingestion induces osteoclastogenesis and bone loss through IL-6 in mice

Abstract

To investigate the role of IL-6 in alcohol-mediated osteoporosis, we measured a variety of bone remodeling parameters in wild-type (il6+/+) or IL-6 gene knockout (il6–/–) mice that were fed either control or ethanol liquid diets for 4 months. In the il6+/+ mice, ethanol ingestion decreased bone mineral density, as determined by dual-energy densitometry; decreased cancellous bone volume and trabecular width and increased trabecular spacing and osteoclast surface, as determined by histomorphometry of the femur; increased urinary deoxypyridinolines, as determined by ELISA; and increased CFU-GM formation and osteoclastogenesis as determined ex vivo in bone marrow cell cultures. In contrast, ethanol ingestion did not alter any of these parameters in the il6–/– mice. Ethanol increased receptor activator of NF-κB ligand (RANKL) mRNA expression in the bone marrow of il6+/+ but not il6–/– mice. Additionally, ethanol decreased several osteoblastic parameters including osteoblast perimeter and osteoblast culture calcium retention in both il6+/+ and il6–/– mice. These findings demonstrate that ethanol induces bone loss through IL-6. Furthermore, they suggest that IL-6 achieves this effect by inducing RANKL and promoting CFU-GM formation and osteoclastogenesis.

Authors

Jinlu Dai, Dinlii Lin, Jian Zhang, Paula Habib, Peter Smith, Jill Murtha, Zheng Fu, Zhi Yao, Yinghua Qi, Evan T. Keller

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Effect of ethanol ingestion on CFU-GM formation, osteoclastogenesis, and...
Effect of ethanol ingestion on CFU-GM formation, osteoclastogenesis, and RANKL mRNA expression in the bone marrow of wild-type or IL-6 gene knockout mice. Il6+/+ or il6–/– mice were fed either a control diet or 5% ethanol diet for 4 months. The mice were then sacrificed, and bone marrow was collected from the femur. (a) CFU-GM formation was determined as described in Methods. Data are presented as mean (± SD) CFU-GM formed per 5.5 × 105 nucleated bone marrow cells. (b) Osteoclast formation was determined in marrow cultures maintained for 9 days in the presence of 10 nM 1,25(OH)2D3. Osteoclast numbers were determined by counting cells that bound I-125-calcitonin and were TRAPase-positive as described in Methods. Data are presented as mean (± SD) osteoclasts per 1.5 × 106 nucleated bone marrow cells. (c) RANKL mRNA expression was determined by subjecting bone marrow cell total RNA to RT-PCR for RANKL and β-actin mRNA as described in Methods. Density of individual bands was determined. A representative gel is shown. Data are presented as mean (± SD) relative density of RANKL PCR product bands normalized with β-actin PCR product bands. (d)Data were analyzed using ANOVA and Fisher’s least significant difference for post hoc analysis. AP < 0.001 compared with control-fed il6+/+ mice. BP = 0.033 compared with control-fed il6+/+ mice. CP < 0.01 compared with control-fed il6+/+ mice. Measurements were performed on ten individual mice per group for CFU-GM and osteoclast studies and four individual mice per group for RANKL mRNA determination.