Background/Purpose: Inflamm-aging is a sterile, low-grade, chronic systemic inflammatory state characterized by an increase in proinflammatory cytokines involved in the development of most age-related diseases such as cancer, Alzheimer’s disease, type 2 diabetes, stroke, cardiovascular disease, and rheumatoid arthritis (RA). Because cellular metabolism modulates T cell function, metabolic changes can be hypothesized to promote the reprogramming of memory CD4+ T cells into senescent CD4+ T cells and contribute to memory CD4+ T cell dysfunction during aging. Therefore, we hypothesized that metabolic reprogramming of CD4+ T cells may be a major factor promoting immune cell dysfunction during aging, contributing to the pathogenesis of age-related diseases such as RA.

Methods: To this end, we analyzed memory CD4+ T cells isolated from PBMCs from young donors (20-32 years) and old donors (52-67 years) using MACSTM technology. Ex vivo memory CD4+ T cells were analyzed using Seahorse^TM technology to determine proton efflux rate (PER) as a measure of glycolysis (glycoPER) and oxygen consumption rate (OCR) as a measure of mitochondrial respiration (mitoOCR). Cytokine secretion was measured by flow cytometry and multiplex assay with and without mitotempo, an inhibitor of mitochondrial reactive oxygen species (ROS). Finally, TCR-stimulated proliferation of memory CD4+ T cells was determined by flow cytometry using CSFE and Ki-67 at 3 and 4 days. ROS and mitochondrial activity were analyzed by flow cytometry after 24 h using DCF-DA as well as CellROX Deep Red and Mitotracker.

Results: In a quiescent state, memory CD4+ T cells from elderly individuals demonstrated a decrease in basal glycolysis and compensatory glycolysis, and an increase in the ratio of basal mitoOCR to glycoPER while their mitochondrial profile was equivalent to that of young donors while the number of mitochondria was higher with no increase in steady-state ATP level. In this line and in comparison, to the younger reference group, memory CD4+ T cells from aged donors presented a greater spare respiratory capacity after TCR-activation and a marked increase in intracellular ROS production. Interestingly, we did not observe an impact of aging on memory CD4+ T cell proliferation as determined by CFSE and Ki-67. Although the capacity of intracellular cytokine expression did not differ between the compared groups, the levels of secreted IFN-γ, IP-10, IL-4, IL-6, IL-9, and MCAF were significantly higher in the supernatants of memory CD4+ T cells taken from aged donors but were sensitive to ROS inhibition.

Conclusion: These findings suggest that metabolic reprogramming in human memory CD4+ T cells during aging results in an increased expression of proinflammatory cytokines as a result of ROS production and mitochondrial dysfunction. This process may culminate in T cell dysfunction and thus contribute to the pathogenesis of inflamm-aging and the development of age-related diseases such as rheumatoid arthritis (RA).

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/age-related-metabolic-reprogramming-of-memory-cd4-t-cells-is-associated-with-reactive-oxygen-species-induced-immune-cell-dysfunction/