Magnesium sulfate inhibits binding of lipopolysaccharide to THP-1 cells by reducing expression of cluster of differentiation 14
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We investigated effects of magnesium sulfate (MgSO4) on modulating lipopolysaccharide (LPS)–macrophage binding and cluster of differentiation 14 (CD14) expression. Flow cytometry data revealed that the mean levels of LPS-macrophage binding and membrane-bound CD14 expression (mCD14) in differentiated THP-1 cells (a human monocytic cell line) treated with LPS plus MgSO4 (the LPS + M group) decreased by 28.2% and 25.3% compared with those THP-1 cells treated with LPS only (the LPS group) (P < 0.001 and P = 0.037), indicating that MgSO4 significantly inhibits LPS–macrophage binding and mCD14 expression. Notably, these effects of MgSO4 were counteracted by L-type calcium channel activation. Moreover, the mean level of soluble CD14 (sCD14; proteolytic cleavage product of CD14) in the LPS + M group was 25.6% higher than in the LPS group (P < 0.001), indicating that MgSO4 significantly enhances CD14 proteolytic cleavage. Of note, serine protease inhibition mitigated effects of MgSO4 on both decreasing mCD14 and increasing sCD14. In conclusion, MgSO4 inhibits LPS–macrophage binding through reducing CD14 expression. The mechanisms may involve antagonizing L-type calcium channels and activating serine proteases.
KeywordsCD14 MgSO4 Calcium L-type calcium channels Protease
The authors thank Ms. Tai-Hsin Chang and Ms. Ching-Yun Chang for their excellent laboratory technical assistance. This study was supported by a grant from the Ministry of Science and Technology, Taiwan (MOST 105-2314-B-303-001-MY3), awarded to CJH.
YYC and CJH contributed to the study concept and design; data collection, analysis, and interpretation; and writing and critical revision of the article. TYL, MCK, TYC, CFC, and CSW contributed to data analysis and interpretation as well as writing and critical revision of the article.
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