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Lipoprotein activated macrophages in co-culture with mesangial and endothelial cells: nitric oxide and tissue injury
1Department of Pathology, University of Mississippi Medical Center, Jackson 39216, USA.
Abstract:
Experiments were conducted to test the hypothesis that VLDL induced excess NO in macrophages may be the mechanism of tissue injury that explains the risk associated with VLDL towards the development of cardiovascular and renal diseases. VLDL activated macrophages were co-cultured with endothelial and mesangial cells. The results showed 59-63 fold higher NO production in VLDL activated macrophages compared to the unactivated macrophages. Nitric oxide production was further potentiated by an additional four fold (241 fold) in VLDL activated macrophage/mesangial cell co-cultures. In co-cultures of VLDL activated macrophages/endothelial cells, NO production was 47 fold higher than the corresponding controls. Cell injury as measured by lactate dehydrogenase activity in cell culture supernatant was elevated in co-cultures of VLDL activated macrophage and mesangial or endothelial cells. Endothelial cells were more susceptible to nitric oxide mediated injury than mesangial cells. On the other hand, low density lipoprotein (LDL) activated macrophages did not generate significant NO or exert toxicity. These results provide support for the mechanism by which VLDL can cause tissue injury and highlights increased nitric oxide production due to the interaction between VLDL activated macrophages and mesangial cells.
Insights
Very-low-density lipoprotein (VLDL) triggers excess nitric oxide (NO) in macrophages, causing tissue injury linked to cardiovascular and renal diseases. This NO overproduction, especially with mesangial cells, explains VLDL
Area of Science:
- Biochemistry
- Cell Biology
- Pathology
Background:
- Cardiovascular and renal diseases are significant health concerns.
- Very-low-density lipoprotein (VLDL) is implicated in the pathogenesis of these diseases.
- The precise mechanism of VLDL-induced tissue injury remains incompletely understood.
Purpose of the Study:
- To investigate the hypothesis that VLDL-induced excess nitric oxide (NO) in macrophages mediates tissue injury.
- To explore the role of VLDL-activated macrophages in endothelial and mesangial cell damage.
- To compare the effects of VLDL with low-density lipoprotein (LDL) on macrophage activation and toxicity.
Main Methods:
- Co-culture of VLDL-activated macrophages with endothelial and mesangial cells.
- Quantification of nitric oxide (NO) production using established assays.
- Assessment of cell injury via lactate dehydrogenase (LDH) activity measurements.
- Comparative analysis of VLDL and LDL effects on macrophage-induced toxicity.
Main Results:
- VLDL-activated macrophages exhibited a 59-63 fold increase in NO production compared to controls.
- Co-culture with mesangial cells potentiated NO production by an additional four-fold (241-fold total).
- Co-culture with endothelial cells resulted in a 47-fold increase in NO production.
- Elevated LDH activity indicated significant cell injury in co-cultures, with endothelial cells being more susceptible to NO-mediated damage.
- LDL-activated macrophages did not induce significant NO production or toxicity.
Conclusions:
- VLDL-induced excess NO production in macrophages is a key mechanism contributing to tissue injury.
- The interaction between VLDL-activated macrophages and mesangial cells significantly enhances NO production and subsequent damage.
- These findings elucidate a pathway linking VLDL to cardiovascular and renal disease development via NO-mediated cytotoxicity.