Background/Purpose: Age-related impairment of characteristic neutrophil functions is well described (Fortin, McDonald et al. 2008). However, experimental evidence for age-related alterations of neutrophil metabolic adaptation towards nutrient deprivation -a feature of neutrophil battlefields- remains elusive. Moreover, differences in neutrophil metabolic adaptation may contribute to age-related pathologies such as autoimmune diseases including rheumatoid arthritis or other pathologies as atherosclerosis or cancer.

Therefore, we hypothesized that metabolic adaptation of human neutrophils to glucose deprivation is impaired with increasing age.

Methods: In order to test the hypothesis, we compared isolated human peripheral CD15+ neutrophils from four healthy young donors (mean age: 23.4 ± 2.7) with four healthy elderly donors (mean age of 58.7 ± 2.4). First, we analyzed the survival of neutrophils either stimulated with PMA or left untreated and subsequently incubated for 0 h and 6 h under various glucose concentrations (0, 1, 5, and 10 mM). To address this, we performed 7-AAD staining by flow cytometry, while basal respiration, ATP-bound respiration, maximal respiration, and spare capacity were determined using Seahorse^TM technology.

Results: We observed that neutrophils (purity > 97%) survived for 6 hours in vitro, independent of treatment with PMA or glucose concentrations in the culture medium. With minor differences between the various concentrations of glucose used, the percentage of living cells after 6 h was 95% ± 2.5 without PMA and 75% ± 4.7 with PMA stimulation. No differences were uncovered between the two age groups. However, Seahorse™ technology revealed significant differences in basal, maximal, and spare respiratory capacity. Briefly, oxygen consumption rate (OCR; pmol/min/cell count) with respect to basal, maximal and reserve respiratory capacity was lower in the elderly donors compared to the young donors. For instance, with a concentration of 5 mM glucose, the OCR was 17 ± 0.7 in elderly donors compared to 22.5 ± 1 in young donors, while the maximal respiration was 25 ± 0.8 in elderly and 41 ± 0.6 in the young donor group. Interestingly, these differences were independent of glucose concentrations in the medium.

Conclusion: Our initial experiments show that basal metabolic parameters differ between neutrophils from young and older donors. Further experiments are needed to understand in detail the mechanisms and effects of age-related differences in metabolism on neutrophil functions.

« Back to ACR Convergence 2021

ACR Meeting Abstracts - https://acrabstracts.org/abstract/increasing-age-impairs-the-metabolic-adaptation-of-human-neutrophils-to-glucose-deprivation/