Lower Metabolic Potential and Impaired Metabolic Flexibility in Human Lymph Node Stromal Cells from Patients with Rheumatoid Arthritis

Abstract

Cellular metabolism is important for determining cell function and shaping immune responses. Studies have shown a crucial role for stromal cells in steering proper immune responses in the lymph node microenvironment. These lymph node stromal cells (LNSCs) tightly regulate immune tolerance. We hypothesize that malfunctioning LNSCs create a microenvironment in which normal immune responses are not properly controlled, possibly leading to the development of autoimmune diseases such as rheumatoid arthritis (RA). Therefore, we set out to determine their metabolic profile during health and systemic autoimmunity. We included autoantibody positive individuals at risk of developing RA (RA-risk individuals), RA patients and healthy volunteers. All study subjects underwent lymph node biopsy sampling. Mitochondrial function in cultured LNSCs was assessed by quantitative PCR, flow cytometry, Seahorse and oleate oxidation assays. Overall, mitochondrial respiration was lower in RA(-risk) LNSCs compared with healthy LNSCs, while metabolic potential was only lower in RA LNSCs. To maintain basal mitochondrial respiration, all LNSCs were mostly dependent on fatty acid oxidation. However, RA(-risk) LNSCs were also dependent on glutamine oxidation. Finally, we showed that RA LNSCs have impaired metabolic flexibility. Our results show that the metabolic landscape of LNSCs is not only altered during established disease, but partly already in individuals at risk of developing RA. Future studies are needed to investigate the impact of restoring metabolic capacity in LNSC-mediated immunomodulation and disease progression.

Senescence phenotype of lymph node stromal cells from patients with rheumatoid arthritis is partly restored by dasatinib treatment

“…These lipofuscin granules contain highly oxidized proteins, mostly unsaturated fatty acids, that cannot be removed by proteasomal degradation and accumulate in lysosomes with age (40, 41). We previously showed increased ROS production by RA LNSCs (42) and here we observed significantly more lipofuscin granules already in RA-risk LNSCs. In aggregate, this indicates that detected autofluorescence in RA(– risk) LNSCs may reflect increased lysosomal content and oxidative stress.…”

“…CD38 levels inversely correlate with the age-related decline in nicotinamide adenine dinucleotide (NAD), which ultimately leads to mitochondrial dysfunction and metabolic alterations (45, 46). It is interesting to postulate that our earlier detected metabolic alteration in LNSCs (42) is related to altered CD38 and NAD+ levels. Additional research is needed to investigate whether the differential expression of these genes are causative related to the observed senescence phenotype of RA LNSCs and may guide future studies aimed at restoring LNSC function.…”

Impact of SARS-CoV-2 mRNA vaccine on arthritis condition in rheumatoid arthritis

“…While our study also cannot definitively establish whether the SARS-CoV-2 vaccine directly worsened RA, it is possible that mRNA vaccination could serve as an aggravating factor in RA as, for instance, smoking, obesity and environmental factors might ( 19 ). Recent study has shown the distinct different metabolic alterations of local lymph node stromal microenvironment in RA patients compared with healthy controls ( 20 ). Thus, the present result suggests that for some RA patients, the SARS-CoV-2 vaccine might act as a potential trigger for exacerbation of arthritis compared with healthy individuals.…”

Identification and mapping of human lymph node stromal cell subsets by combining single-cell RNA sequencing with spatial transcriptomics

“…In our dataset, CCL19+ SCs express high levels of CCL2 in the vessel-rich areas of the T cell zone where they might attract monocytes, as previously described in FRCs dwelling the T cell zone 34 . Furthermore, it is worth noting that LNSC predominantly rely on fatty acid metabolism 35 . This is evident through the high expression in CCL19+ SCs of CD36, FABP4, and FABP5, proteins that play crucial roles in the fatty acid metabolism 36 , FABP4 and FABP5 also are involved in the maintenance of T lymphocyte homeostasis through the modulation of cytokine production in thymic stromal cells 37 .…”