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Saturated Fatty Acids Induce Ceramide-associated Macrophage Cell Death
Published on: October 31, 2017
Inhibitory effect of polyunsaturated fatty acids on apoptosis induced by Streptococcus pneumoniae in alveolar
Archana Saini1, Kusum Harjai, Sanjay Chhibber
1Department of Microbiology, Panjab University, Chandigarh, India.
Background & Objectives:
Apoptosis is considered as a major defense mechanism of the body. Multiple pathogens induce macrophage apoptosis as a mode of immune evasion. In earlier studies, n-3 polyunsaturated fatty acids (PUFA) have been reported to be protective against neuronal apoptosis and neuronal degeneration, seen after spinal cord injury. In this study, we tried to evaluate the role of n-3 polyunsaturated fatty acids on the process of macrophage phagocytic activity and apoptosis in mice.
Methods:
Mice were divided into three groups (n=60); Group I was fed on sea cod oil; Group II on flaxseed oil supplementation for 9 wk along with standard laboratory chow diet. Group III was fed on standard diet and served as control. After supplementation, phagocytic and apoptotic (morphological staining: acridine orange plus ethidium bromide; H-33342 plus propidium iodide staining and DNA ladder formation) activities of mouse alveolar macrophages were assessed.
Results:
Alveolar macrophages (obtained from sea cod oil and flaxseed oil fed group mice) showed significant increase in bacterial uptake as well as intracellular killing (P 0.05) of Streptococcus pneumoniae. Significant decrease (P<0.05) in apoptotic cells was observed among alveolar macrophages from sea cod and flaxseed oil fed mice whereas maximum apoptosis was observed in control alveolar macrophages on interaction with bacteria in vitro which was confirmed by DNA laddering.
Interpretation & Conclusions:
These findings suggest that dietary supplementation with n-3 polyunsaturated fatty acids to mice led to enhanced phagocytic capability of their alveolar macrophages as well as provided protection against apoptosis upon challenge with S. pneumoniae.
Insights
Dietary n-3 polyunsaturated fatty acids (PUFA) enhance macrophage phagocytosis and reduce apoptosis. Supplementation with fish or flaxseed oil boosted bacterial clearance and protected macrophages from programmed cell death.
Area of Science:
- Immunology
- Nutrition Science
Background:
- Macrophage apoptosis is a key immune evasion strategy used by pathogens.
- n-3 polyunsaturated fatty acids (PUFA) have shown neuroprotective effects against apoptosis.
Purpose of the Study:
- To investigate the impact of n-3 PUFA on macrophage phagocytic activity and apoptosis.
- To evaluate the role of dietary n-3 PUFA in modulating immune responses.
Main Methods:
- Mice were supplemented with sea cod oil or flaxseed oil for 9 weeks.
- Phagocytic activity and apoptosis of alveolar macrophages were assessed in vitro.
- Methods included morphological staining and DNA ladder formation assays.
Main Results:
- Macrophages from n-3 PUFA supplemented mice showed significantly increased bacterial uptake and killing of Streptococcus pneumoniae.
- A significant reduction in macrophage apoptosis was observed in the sea cod oil and flaxseed oil groups.
- Control group macrophages exhibited maximum apoptosis upon bacterial interaction.
Conclusions:
- Dietary n-3 PUFA supplementation enhances the phagocytic capacity of alveolar macrophages.
- n-3 PUFA provides protection against macrophage apoptosis when challenged with S. pneumoniae.
- These findings highlight the immunomodulatory role of n-3 fatty acids in host defense.
