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Immun Ageing. 2019 Jan 26;16:3. doi: 10.1186/s12979-019-0143-1. eCollection 2019.

Classical monocytes maintain ex vivo glycolytic metabolism and early but not later inflammatory responses in older adults.

Author information

1
School of Health Studies, Memphis, TN 38152 USA.
2
2Center for Nutraceutical and Dietary Supplement Research, University of Memphis, Memphis, TN 38152 USA.
3
3304 Elma Roane Fieldhouse, University of Memphis, Memphis, TN 38152 USA.

Abstract

Background:

Inflammaging is a condition of chronic low-grade inflammation due to the aging process and is associated with a variety of chronic diseases. Monocytes are innate immune cells which contribute to inflammation and are dysregulated during aging, demonstrated reduced phagocytosis, increased inflammation, and alterations in subset proportions. Metabolism is known to determine immune cell function, with quiescent and anti-inflammatory cells primarily relying on fatty acid oxidation, while activated and inflammatory cells primarily rely on glycolysis. We have previously shown an age-related decrease in mitochondrial respiratory capacity in monocytes, so we hypothesized here that a compensatory shift toward glycolysis would occur which would also exacerbate inflammation.

Results:

Using Seahorse assays, we profiled glycolysis in classical monocytes isolated from older (60-80 yr) and younger (18-35 yr) adults. Aging did not affect parameters of basal glycolysis in the glycolysis stress test, nor did it alter glycolytic activation early (2 h) or later (24 h) post-LPS stimulation. Cytokine gene expression was unchanged between aged and young subjects at 2 h post-LPS but was reduced in older subjects at 24 h post-LPS either significantly (IL1B) or near-significantly (IL6, IL10).

Conclusions:

Aging appears not to affect glycolytic metabolism ex vivo in classical monocytes, but may reduce cytokine expression at later timepoints. Studies examining monocytes stimulated with age-altered circulating factors or with other pattern recognition receptor agonists may shed further light on monocyte metabolism as a determinant of immunosenescence and inflammaging.

KEYWORDS:

Glycolysis; Immunometabolism; Immunosenescence; Inflammaging; Inflammation; Innate immunity; Metabolism

Conflict of interest statement

All study activities were approved by the Institutional Review Board at the University of Memphis (protocol #4361). Subjects provided informed consent and were free to withdraw at any time.Not applicable.The authors declare that they have no competing interests.Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

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