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AB0031 METABOLIC ADAPTATION OF HUMAN NEUTROPHILS TO GLUCOSE DEPRIVATION IS IMPAIRED WITH INCREASING AGE

Age-related impairment of classical 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, age-related differences in neutrophil metabolic adaptation may contribute to age-related pathologies such as atherosclerosis, cancer, and autoimmune diseases including rheumatoid arthritis.Therefore, we hypothesized that metabolic adaptation of human neutrophils to glucose deprivation is impaired with increasing age.We isolated human peripheral CD15+ neutrophils from four healthy young donors (mean age: 23.4 ± 2.7) and four healthy donors with a 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 varying glucose concentrations (0, 0.5, 1, 5, and 10 mM). To address this, we used 7-AAD staining and flow cytometry. Using Seahorse™ technology, we determined basal respiration, ATP-bound respiration, and maximal and spare capacity.We show that neutrophils (purity > 95%) survived for 6 hours in vitro, independent of treatment with PMA or concentrations of glucose in the culture medium. With negligible 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 in this respect between the two age groups. However, Seahorse™ technology revealed significant differences in basal, maximal, and spare respiratory capacity. Briefly, 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 basal respiration (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 concentration in the medium.Our data 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.[1]Fortin, C. F., P. P. McDonald, O. Lesur and T. Fülöp, Jr. (2008). “Aging and neutrophils: there is still much to do.” Rejuvenation Res11(5): 873-882.None declared