Healthy and premature aging of monocytes and macrophages

Abstract

Aging is associated with immunosenescence, a decline in immune functions, but also with inflammaging, a chronic, low-grade inflammation, contributing to immunosenescence. Monocytes and macrophages belong to the innate immune system and aging has a profound impact on these cells, leading to functional changes and most importantly, to the secretion of pro-inflammatory cytokines and thereby contributing to inflammaging. Rheumatoid arthritis (RA) is an autoimmune disease and age is an important risk factor for developing RA. RA is associated with the early development of age-related co-morbidities like cardiovascular manifestations and osteoporosis. The immune system of RA patients shows signs of premature aging like age-inappropriate increased production of myeloid cells, accelerated telomeric erosion, and the uncontrolled production of pro-inflammatory cytokines. In this review we discuss the influence of aging on monocytes and macrophages during healthy aging and premature aging in rheumatoid arthritis.

Keywords: aging; immunosenescence; inflammaging; macrophages; monocyte metabolism; monocytes; rheumatoid arthritis.

Figure 1

Impact of healthy aging on monocytes and macrophages. Schematic diagram displaying the consequence of aging on the phenotype and functions of monocytes and macrophages in healthy individuals. IL-6, interleukin-6, TNFα, tumor necrosis factor α, IL-1β, interleukin-1β, ROS, reactive oxygen species (created in BioRender.com).

Figure 2

Premature aging in monocytes and macrophages in rheumatoid arthritis. Schematic diagram showing the effect of RA on age-related changes in monocyte and macrophage phenotypes and functions. IL-6, interleukin-6, TNFα, tumor necrosis factor α, IL-1β, interleukin-1β, ROS, reactive oxygen species, CM, classical monocytes, IM, intermediate monocytes, NCM, non-classical monocytes, NADPH, nicotinamide adenine dinucleotide phosphate (created in BioRender.com).