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. Author manuscript; available in PMC: 2022 Jun 1.
Published in final edited form as: Nat Immunol. 2021 Nov 22;22(12):1551–1562. doi: 10.1038/s41590-021-01065-2

Fig. 1. Mitochondrial insufficiency and ER expansion in rheumatoid arthritis.

Fig. 1.

Naïve CD4+CD45RA+ T cells from patients with RA or psoriatic arthritis (PsA) and age-matched healthy individuals were stimulated for 72 h. (a-c) Reduced mitochondrial fitness in RA T cells. (a) Basal mitochondrial oxygen consumption rates (OCR) measured by Seahorse Analyzer. n=6 each. (b, c) Mitochondrial membrane potential measured by flow cytometry (MitoTracker Red). n=7 each. (d) Correlation of ER size (ER Tracker MFI) and mitochondrial membrane potential in healthy T cells by Linear regression (n=10). (e) Representative confocal microscopy imaging of the ER enzyme protein disulfide isomerase (PDI) and mitochondrial membrane potential (MitoTracker Red) from 3 independent experiments. Green arrow marks a cell with abundant ER, red arrow marks a cell with high mitochondrial activity. Scale bar, 10 μm. (f) Correlation of ER size (ER Tracker intensity) and mitochondrial membrane potential in cells gated based on cell size. Linear regression with confidence interval shown in gray around the regression line. (g-l) Expanded ER size in RA T cells. (g) Flow cytometric quantification of ER size (ER Tracker MFI) in RA and healthy control T cells; n = 8 each. (h, i) Confocal microscopy imaging of the ER chaperon protein calnexin in RA and healthy T cells. Scale bar, 10 μm. Single cell calnexin intensity quantification (n=50 T cells from 5 healthy and 5 RA samples). (j) Flow cytometric quantification of ER size in T cells from PsA patients and healthy donors; n = 8 each. (k) Intracellular phosphatidylcholine concentrations in healthy and RA T cells (Healthy: n=6; RA: n =8). (l) Representative transmission electron microscope image of healthy and RA T cells from 30 cells from 3 healthy and 3 RA samples. White arrows indicate ER. Scale bar,1 μm. All data are mean ± SEM. Two-tailed unpaired Mann-Whitney-Wilcoxon rank test (a, c, g-k). *P < 0.05, **P < 0.01, ***P < 0.001.