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Altered macrophage intracellular signaling induced by protein-calorie malnutrition
M D McCarter1, H A Naama, J Shou
1Department of Surgery, New York Hospital-Cornell University Medical College, New York 10021, USA.
Abstract:
Protein-calorie malnutrition (PCM) contributes to increased morbidity and mortality through impairment of host defense mechanisms and reduced macrophage function. The present study examined alterations in macrophage intracellular signaling associated with the impairment in host defense capabilities. Mice were randomized to either control (regular diet) or protein-free diets (PCM) and pair-fed for 1 week. Following endotoxin stimulation, peritoneal macrophages from PCM mice produce significantly less TNF-alpha and IL-6 product and had significantly less cell-associated IL-6 when compared to macrophages from control mice. Similarly, macrophages from PCM mice had a significant reduction in mRNA levels for both TNF-alpha and IL-6. Other macrophage intracellular signaling mechanisms, such as calcium flux and tyrosine kinase phosphorylation were also altered by PCM. The etiology of PCM-induced defects in macrophage function and intracellular signaling remain unknown but may be related to the neuroendocrine response to PCM.
Insights
Protein-calorie malnutrition impairs macrophage function, reducing key immune responses like TNF-alpha and IL-6 production. This study investigates the underlying intracellular signaling defects caused by malnutrition.
Area of Science:
- Immunology
- Nutrition Science
- Cellular Biology
Background:
- Protein-calorie malnutrition (PCM) is linked to increased illness and death.
- PCM impairs host defense mechanisms, particularly macrophage function.
- Understanding these impairments is crucial for improving patient outcomes.
Purpose of the Study:
- To investigate alterations in macrophage intracellular signaling pathways due to PCM.
- To determine the impact of PCM on macrophage cytokine production and gene expression.
- To explore potential mechanisms behind PCM-induced macrophage dysfunction.
Main Methods:
- Mice were fed either a control diet or a protein-free diet (PCM) for one week.
- Peritoneal macrophages were isolated and stimulated with endotoxin.
- Levels of TNF-alpha, IL-6, and intracellular signaling molecules (calcium flux, tyrosine kinase phosphorylation) were measured.
Main Results:
- Macrophages from PCM mice produced significantly less TNF-alpha and IL-6 compared to controls.
- Reduced mRNA levels for TNF-alpha and IL-6 were observed in PCM macrophages.
- PCM altered macrophage intracellular signaling, including calcium flux and tyrosine kinase phosphorylation.
Conclusions:
- PCM significantly impairs macrophage function, affecting cytokine production and intracellular signaling.
- These defects may compromise host defense capabilities.
- The exact cause of PCM-induced macrophage dysfunction is unknown but may involve neuroendocrine responses.