Critical Care: Mechanisms of Lung Injury |

Mitogen-Activated Protein Kinase Pathway Mediates LPS-Induced Apoptosis in RAW 264.7 Macrophages With the Over-Expression of Vitamin D-Binding Protein FREE TO VIEW

Duchao Zhang; Lixin Xie
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Chinese PLA General Hospital, Beijing, China

Copyright 2016, American College of Chest Physicians. All Rights Reserved.

Chest. 2016;149(4_S):A185. doi:10.1016/j.chest.2016.02.191
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SESSION TITLE: Mechanisms of Lung Injury

SESSION TYPE: Original Investigation Slide

PRESENTED ON: Saturday, April 16, 2016 at 04:00 PM - 05:00 PM

PURPOSE: Vitamin D-binding protein (VDBP), known as group-specific component globulin (Gc-globulin), is a multi-functional plasma protein with many important functions such as transport of vitamin D and modulates immune and inflammatory responses via a macrophage-activating factor (known as Gc-globulin-MAF through partial deglycosylation. In this study, we investigated the effect of LPS-induced apoptosis in RAW 264.7 macrophages with the over-expression of Vitamin D-binding proteinand the underlying intracellular signal transduction pathways.

METHODS: The RAW264. 7 cell strain with stable expression of VDBP was screened with puromycin and analyzed with flow cytometry and fluorescent microscopy for infection efficiency. Annexin V-FITC/PI apoptosis detection kit was used to test apoptosis of RAW 264.7 macrophages with the over-expression of Vitamin D-binding protein after induced by LPS for 12 hours. Western-blot was used to investigate intracellular signal transduction pathways, including proapoptotic caspase-3, -8, and -9 activities and mitogen-activated protein kinase (MAPK) pathways.

RESULTS: Compared to the control cell strain, the apoptosis ratio of LPS-induced RAW264. 7 cell strain with stable expression of VDBP was increased (18.5% vs. 25.1%). Expressions of proapoptotic caspase-3, -8, and -9 activities and phosphorylation of p38 and JNK1/2 in RAW264. 7 cell strain with stable expression of VDBP were enhanced after induced by LPS for 12 hours.

CONCLUSIONS: These results suggest that over-expression of Vitamin D-binding protein in RAW 264.7 macrophages enchanced LPS-induced apoptosis, indicating over expression of VDBP in macrophages may induced apoptosis in sepsis via MAPK pathways.

CLINICAL IMPLICATIONS: Over-expression of Vitamin D-binding protein in macrophages could enchance apoptosis of macrophages after induced by LPS and p38 MAPK pathway plays a crucial role, which indicated that Vitamin D-binding protein may cause apoptosis of the macrophages when activated macrophages are no longer needed at the site of inflammation in patients with sepsis.

DISCLOSURE: The following authors have nothing to disclose: Duchao Zhang, Lixin Xie

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