Reduced bioenergetics and toll-like receptor 1 function in human polymorphonuclear leukocytes in aging

Area of Science:

• Immunology
• Gerontology
• Cellular Biology

Background:

• Aging leads to immunosenescence, a decline in immune function, increasing susceptibility to infections.
• Polymorphonuclear leukocytes (PMN) are crucial for innate immunity, and their function may be compromised with age.

Purpose of the Study:

• To investigate the impact of aging on Toll-like receptor 1 (TLR1) expression and function in PMN.
• To examine age-related changes in PMN bioenergetics and their correlation with immune responses.

Main Methods:

• Compared TLR1 expression and response in PMN from young (21-30 years) and older (>65 years) adults.
• Assessed PMN activation markers (integrins, IL-8, p38 MAP kinase, CD62L) and apoptosis rescue upon TLR1 stimulation.
• Measured glucose uptake and bioenergetic efficiency in PMN from different age groups.

Main Results:

• Older adults exhibited reduced TLR1 expression and impaired TLR1-mediated PMN activation, including lower integrin activation, IL-8 production, and p38 MAP kinase phosphorylation.
• PMN from older adults showed reduced CD62L shedding and less efficient rescue from apoptosis when stimulated via TLR1.
• A significant age-dependent deficiency in PMN bioenergetics, particularly reduced glucose uptake after TLR1 stimulation, was observed in older individuals.

Conclusions:

• Aging is associated with decreased TLR1 expression and function in PMN, alongside impaired bioenergetics.
• These age-related deficits in PMN function likely contribute to increased infection risk in older adults.
• Findings suggest potential therapeutic targets to enhance PMN function in the elderly.