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233 Autoantibody-positive healthy individuals constrain T cell pathways to regulate autoimmune disease
  1. Samantha Slight-Webb1,
  2. Aleksandra Bylinska1,
  3. Miles Smith1,
  4. Rufei Lu1,
  5. Hua Chen1,
  6. Krista Bean1,
  7. Melissa Munroe1,
  8. Holden Maecker2,
  9. Paul J Utz2,
  10. Joan T Merrill1,
  11. Eliza Chakravarty3,
  12. Cristina Arriens1,
  13. Joel Guthridge1 and
  14. Judith A James1
  1. 1Oklahoma Medical Research Foundation
  2. 2Stanford University
  3. 3Oklahoma Medical Research Foundation; University of Oklahoma


Background Anti-nuclear antibody (ANA) positivity is a principal feature of individuals with an autoimmune disease, yet up to one in five healthy individuals are ANA-positive (ANA+) and will never develop overt disease. Understanding differences in immune cell physiology between ANA+healthy individuals and individuals with clinical SLE remains a critical goal in the understanding of SLE pathogenesis across ethnicities.

Methods Blood specimens and information on disease activity were collected from European (EA) and African American (AA) individuals classified and matched in groups as ANA- healthy controls (n=24), ANA +healthy (n=24) or SLE patients (n=24). Single-cell analysis of cell surface markers was completed by mass cytometry on PBMCs and cellular heterogeneity was visualized using tSNE (figure 1A–B) and manual gating. Further, phospho-specific flow cytometry was used to measure basal levels of pERK, pPLCg2 and p38 and expression following CD3/CD28 (TCR) and anti-IgG and IgM (BCR) stimulation. Whole genome RNA-sequencing was performed on flow cytometry sorted T cells, B cells and monocytes from 35 matched ANA-, ANA +and SLE patients followed by weighted correlation network analysis (WGCNA) and pathway enrichment analyses.

Results Both European and African American SLE patients were distinguished from healthy individuals by T cell proliferation (p=0.002) (figure 1C), plasmacytoid dendritic cell activation (p=0.021) and elevated stem cell factor (p=0.0003). EA ANA+healthy individuals exhibited greater immune regulation with reduced T cell numbers (p=0.002) (figure 1C), decreased activation of dendritic cells (p=0.039) and transitional B cells (0.033), and elevated expression of the inhibitory receptor CD85j (p=0.042) on specific immune cell subsets compared to ANA- healthy subjects. Further, a module associated with hematopoiesis, T cell activation and intrinsic apoptosis signaling pathways is expressed at a higher level in T cells of EA ANA+individuals. In contrast, AA ANA+healthy individuals had elevated plasma levels of IL-6 (p=0.018) and reduced inhibitory receptor expression (p=0.0089) compared to ANA- healthy controls. Gene expression modules associated with viral responses and type I IFN pathway activation were identified in AA SLE patient B cells, while similar expression modules were only found in the monocytes of European American SLE patients.

Abstract 233 Figure 1

Calculated cell numbers indicate elevated T cells in SLE patients and suppressed T cells in EA ANA+ healthy individuals. 20 cell surface marker expression is shown using dimensionality reduced t-SNE plots from PBMC data (110,00 cells) derived from 72 samples. (A) A density map is shown depicting the density of cells and are numbered according to phenotypic subset. (B) Density maps depicting European and African American ANA-, ANA+ and SLE patient PBMC t-SNE plots created using all 33 surface markers are plotted. All plots were derived from cumulative data from 12 individuals per group. (C) Cells numbers were calculated from cell subsets using frequencies and total cell counts. Cell numbers for T cells, CD4+ T cells, and CD8+ T cells are shown. *p<0.05, *p<0.01, ***p<0.001

Conclusions These results highlight the importance of stem cell factor and T cell expansion in SLE pathogenesis, and suggest that mechanisms of SLE pathogenesis differ by ethnicity. ANA +European Americans may have more effective regulatory mechanisms in place to prevent transition to classified autoimmune disease.

Funding Source(s): This work was supported by the NIH under award numbers U54GM104938,

U01AI101934, U19AI082714, and P30AR053483.

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