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Age-related decline in ligand-induced actin polymerization in human leukocytes and platelets
Abstract:
The change in monomeric actin was measured in human polymorphonuclear leukocytes (PMN) and platelets, using the DNase I inhibition assay, after stimulation with various agents. PMN were stimulated with the chemotactic peptide n-formyl-methionyl-leucyl-phenylalanine (FMLP) in 199 donors, the tumor promoter phorbol myristate acetate in 112 donors, and the hormones tri-iodothyronine and phenylephrine, in 118 donors. The donors ranged in age from 20 to 89 years. A decrease in ligand-induced actin polymerization was detected in PMN obtained from the older population, on stimulation with FMLP (p = .014) and PMA (p = .0038). In platelets stimulated with thrombin (163 donors) a significant decrease in actin polymerization also was noted in the older group (p = .017). In addition, in platelets actin polymerization was less in women compared with men (p = .042). Because actin polymerization is an event that might have an important role in cellular activation, the age-related decline in the physiological functions might be related to a decrease in ligand-induced actin polymerization.
Insights
Older adults show reduced actin polymerization in immune cells and platelets, potentially explaining age-related declines in physiological functions. This study measured actin changes in polymorphonuclear leukocytes (PMN) and platelets.
Area of Science:
- Cellular Biology
- Immunology
- Gerontology
Background:
- Actin polymerization is crucial for cellular activation and physiological functions.
- Age-related changes in cellular function are well-documented but underlying mechanisms require further investigation.
Purpose of the Study:
- To investigate age-related differences in ligand-induced actin polymerization in human polymorphonuclear leukocytes (PMN) and platelets.
- To explore potential sex-based differences in platelet actin polymerization.
Main Methods:
- The DNase I inhibition assay was used to measure changes in monomeric actin.
- Human PMN and platelets were stimulated with agents including FMLP, PMA, tri-iodothyronine, phenylephrine, and thrombin.
- Donors' ages ranged from 20 to 89 years, with analysis of sex differences in platelet samples.
Main Results:
- A significant decrease in ligand-induced actin polymerization was observed in PMN from older adults upon stimulation with FMLP and PMA.
- Platelets from older adults exhibited a significant decrease in actin polymerization when stimulated with thrombin.
- Platelet actin polymerization was found to be lower in women compared to men.
Conclusions:
- Ligand-induced actin polymerization declines with age in both PMN and platelets.
- The observed age-related decrease in actin polymerization may contribute to the decline in physiological functions seen in older populations.
- Sex differences in platelet actin polymerization warrant further investigation.