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LPS-induced MCP-1, IL-1 beta, and TNF-alpha mRNA expression in isolated erythrocyte-perfused rat kidney
1Department of Immunology, Scripps Research Institute, La Jolla, California 92037.
Abstract:
The capacity of the lipopolysaccharide (LPS)-stimulated isolated erythrocyte-perfused rat kidney (IEPK) to produce monocyte chemoattractant protein-1 (MCP-1), interleukin-1 beta (IL-1 beta), and tumor necrosis factor-alpha (TNF-alpha) mRNA was investigated. The IEPK was chosen to exclude the influence of circulating neutrophils and monocytes that can produce both these mediators when exposed to LPS. The control minimal LPS group (LPS < 10 pg/ml) showed a small increase in mRNA expression for MCP-1, IL-1 beta, and TNF-alpha in the cortex and medulla after 80 min of perfusion when compared with the unperfused left kidney in which no IL-1 beta or TNF-alpha mRNA and only minimal amounts of MCP-1 mRNA were detected. LPS stimulation (1 microgram/ml for 40 or 80 min) increased MCP-1, IL-1 beta, and TNF-alpha mRNA expression, which was found predominately in peritubular capillary endothelial cells by in situ hybridization. The changes were not due to a marked perturbation of LPS on renal hemodynamics. The renal vascular resistance (RVR) remained constant (40 min LPS exposure) or increased only slightly during the last 5-10 min (80 min LPS exposure) compared with a progressive increase in RVR of the minimal LPS group. The hemodynamic effects of LPS on the IEPK appear to counteract the gradual increase in RVR seen in the minimal LPS group.
Insights
Lipopolysaccharide (LPS) stimulates kidney cells to produce inflammatory mRNA, primarily in endothelial cells. This occurs independently of circulating immune cells and without significant negative effects on kidney blood flow.
Area of Science:
- Renal physiology
- Immunology
- Molecular biology
Background:
- Lipopolysaccharide (LPS) is a potent immune stimulant.
- Kidney cells can produce inflammatory mediators in response to LPS.
- The isolated erythrocyte-perfused rat kidney (IEPK) model allows investigation without circulating immune cells.
Purpose of the Study:
- To investigate the capacity of the IEPK to produce monocyte chemoattractant protein-1 (MCP-1), interleukin-1 beta (IL-1 beta), and tumor necrosis factor-alpha (TNF-alpha) mRNA following LPS stimulation.
- To determine the cellular localization of this mRNA expression.
- To assess the impact of LPS on renal hemodynamics.
Main Methods:
- Isolated erythrocyte-perfused rat kidney (IEPK) model.
- Lipopolysaccharide (LPS) stimulation at 1 microgram/ml for 40 or 80 minutes.
- Quantitative mRNA expression analysis.
- In situ hybridization for cellular localization.
- Renal vascular resistance (RVR) monitoring.
Main Results:
- LPS stimulation significantly increased mRNA expression for MCP-1, IL-1 beta, and TNF-alpha in the kidney cortex and medulla compared to minimal LPS controls.
- mRNA expression was predominantly localized to peritubular capillary endothelial cells.
- Renal vascular resistance (RVR) remained stable or increased only slightly, indicating minimal hemodynamic perturbation.
Conclusions:
- The isolated kidney can produce inflammatory mRNA in response to LPS, primarily within endothelial cells.
- These inflammatory responses occur independently of circulating neutrophils and monocytes.
- LPS-induced changes in the IEPK do not cause significant detrimental hemodynamic effects.