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Abstract: TH-PO833

B Cell Subsets and Signatures in Lupus Nephritis Patients Receiving Mycophenolate or Azathioprine Maintenance

Session Information

Category: Glomerular Diseases

  • 1202 Glomerular Diseases: Immunology and Inflammation

Authors

  • Yap, Desmond Y.H., Queen Mary Hospital, Hong Kong, Hong kong, China
  • Lee, Paul, The University of Hong Kong, Hong Kong, China
  • Tam, Cheryl, The University of Hong Kong, Hong Kong, China
  • Yam, Irene, The University of Hong Kong, Hong Kong, China
  • Yung, Susan, The University of Hong Kong, Hong Kong, China
  • Chan, Daniel Tak Mao, Queen Mary Hospital, Hong Kong, Hong kong, China
Background

Mycophenolate mofetil (MMF) and azathioprine (AZA) are standard maintenance agents for lupus nephritis (LN), and recent data suggested that MMF confers lower long-term flare risk. Aberrant B cell profiles have been implicated in LN pathogenesis, but the effect of MMF and AZA on B cell subsets and related signatures has not been investigated.

Methods

We measured the B cell subsets and serum and intracellular levels of relevant B cell signatures (miRNA148a, BACH1, BACH2 and PAX5) in stable LN patients receiving MMF or AZA (n=10 in each group), combined with low-dose prednisolone, as maintenance immunosuppression.

Results

The MMF group showed higher % of circulating naïve B cells and lower % of plasma cells (4.8±5.2% and 0.2±0.3% respectively, compared with 0.9±1.5% and 0.8±0.9% in AZA group, p=0.029 and 0.043), but had no difference in circulating memory B cells (p=0.97). The MMF group also showed lower plasma cell/naïve B and memory B/naïve B ratios (0.1±0.2 and 1.3±2.1 respectively, compared with 1.7±1.4 and 1.7±1.1 in AZA group, p=0.003 and 0.023). The MMF group showed numerically higher intracellular BACH1, BACH2 and PAX5 in naïve B cells (relative expression (RQ): 1.2±0.5, 1.4±0.2 and 2.6±1.7 respectively compared with AZA group; p>0.05, for all) (Figure 1A) and in plasma cells (RQ: 1.3±0.1, 1.4±0.3 and 1.3±0.6 respectively compared with AZA group; p>0.05, for all) (Figure 1B), but showed no difference in serum and intracellular miRNA148a.

Conclusion

The alterations in B cell subsets and related signatures might contribute to the differential risk of relapse in patients receiving MMF or AZA maintenance.

Figure 1. Intracellular BACH1, BACH2 and PAX5 expression in (A) naïve B cells and (B) plasma cells of patients receiving mycophenolate or azathioprine maintenance.