1458: Activated Naïve DNA-Reactive B Cells in Lupus Nephritis Patients Are Increased and Associated with Disease Activity

Kittikorn Wangriatisak¹, Francesca Faustini², Charlotte de Vries³, Ravi Kumar Sharma⁴, Caroline Grönwall⁵, Prapaporn Pisitkun⁶, Patchanee Chootong⁷, Vivianne Malmström⁵ and Iva Gunnarsson⁸, ¹Department of Clinical Microbiology and Applied Technology, Faculty of Medical Technology, Mahidol University, Thailand ; Division of Rheumatology, Department of Medicine, Karolinska Institutet, Karolinska University Hospital Solna, Sweden; Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden, ²Division of Rheumatology, Department of Medicine, Karolinska Institutet, Karolinska University Hospital Solna, Sweden; Medicine Unit Dermatology, Gastroenterology, Rheumatology; unit of Rheumatology, Karolinska University Hospital Solna, Stockholm, Sweden, ³Division of Rheumatology, Department of Medicine, Karolinska Institutet, Karolinska University Hospital Solna, Sweden; Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden, ⁴Division of Rheumatology, Department of Medicine Solna, Center for Molecular Medicine, Karolinska University Hospital, Karolinska Institutet, Stockholm, Sweden, ⁵Karolinska Institutet, Stockholm, Sweden, ⁶Division of Allergy Immunology and Rheumatology, Department of Medicine, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bankok, Thailand, ⁷Department of Clinical Microbiology and Applied Technology, Faculty of Medical Technology, Mahidol University, Bangkok, Thailand, ⁸Division of Rheumatology, Department of Medicine, Karolinska Institutet, Karolinska University Hospital Solna, Sweden; Medicine Unit Dermatology, Gastroenterology, Rheumatology; unit of Rheumatology, Karolinska University Hospital Solna, Sweden, Stockholm, Sweden

Background/Purpose: Lupus nephritis (LN) is one of the most severe manifestations of systemic lupus erythematosus (SLE), which is characterized by abnormal B-cell activation and their subsequent differentiation into autoreactive plasma blasts/cells. The heterogeneity of autoreactive B cell subsets and their contribution to the pathogenesis of LN are not well elucidated.

Methods: Thirty-five SLE patients, including twenty-eight with positive anti-dsDNA antibodies (80%), and fifteen healthy controls were recruited in this study. Data are represented as median and interquartile range (IQR). To identify DNA-reactive B cells, a surrogate peptide (DWEYSVWLSN) that serves as dsDNA mimotope was used, as previously shown (Jacobi, Annett M et al. 2009 and Wangriatisak, Kittikorn et al. 2021). The phenotype of peripheral B cell subsets (SLE, n = 37 from 35 patients and HCs, n = 15) and DNA-reactive B cells (SLE, n = 10 and HCs, n = 6) was analyzed by spectral flow cytometry. Correlations between different B-cell subsets and Systemic Lupus Erythematosus Disease Activity Index 2000 (SLEDAI-2K) score, clinical manifestations, and laboratory parameters were assessed.

Results: In SLE patients, the median SLEDAI-2K score was 9 (4-17), median age and disease duration were 34 (28-46) and 9 (1.5-13.0), respectively. Twenty-one patients presented with lupus nephritis (LN), with proliferative (class III, n = 3 and class IV, n = 4), membranous (class V, n = 7) and mixed histological patterns (class III & V, n = 5 and class IV & V, n = 2). Phenotypic analyses showed an expansion of circulating activated naïve (aNAV: CD11c⁺CD21^-CD27^-IgD⁺, p < 0.01), double negative 2 B cells (DN2: CD11c⁺CD21^-CD27^-IgD^-, p < 0.05) and plasmablasts (PB: CD27^hiCD38^hi, p < 0.05) in LN patients, especially in class V, compared to non-LN and age-matched HCs. Intriguingly, an upregulation of CD71, as well as a downregulation of CD95, was observed on both DN2 and PB from patients with LN. Further analysis showed that expansion of DNA-reactive B cells was observed in LN patients (median (IQR): 0.13% (0.095-0.160)) compared with non-LN patients (median (IQR): 0.056% (0.042-0.070), p < 0.05). Surprisingly, the majority of these autoreactive cells were mostly represented by an activated naïve phenotype (CD11c⁺CXCD5^-CD21^-), which was more frequent in patients with LN. The percentage of aNAV B cells were positively associated with DN2 (r = 0.567, p = 0.0003) and PB (r = 0.498, p = 0.002), especially in patients with LN. These expanded aNAV, DN2 and PB showed a significant positive correlation with the SLEDAI-2K index, and were inversely correlated with C3 and C4 levels in LN patients. Furthermore, DN2 and aNAV B cells were expanded in anti-dsDNA positive patients, while a lower frequency of such cells was found in anti-Smith positive patients.

Conclusion: Our data show that aNAV B cells display autoreactivity to dsDNA. The cooperation between these cells and DN2 and PB might be involved in the generation of anti-dsDNA antibody in LN which proceed of these B cell responses might via the extrafollicular pathway.


K. Wangriatisak: None; F. Faustini: None; C. de Vries: None; R. Kumar Sharma: None; C. Grönwall: None; P. Pisitkun: None; P. Chootong: None; V. Malmström: Eli Lilly, 1, Janssen, 5, ONO, 1, Pfizer, 5; I. Gunnarsson: None.