D1-like dopamine receptors promote B-cell differentiation in systemic lupus erythematosus.

Background: Systemic lupus erythematosus (SLE) is an autoimmune disease that currently cannot be completely cured with a great health burden. Since the production of autoantibodies plays a key role in the pathogenesis of SLE, discovering the underlying immunoregulation mechanism of B cells will be helpful for developing promising immunotherapy for SLE. In recent studies, dopamine receptors (DRDs), G protein-coupled receptors that include D1-like and D2-like subtypes, are expressed on B cells and participate in various physiological processes, involving immune responses. However, the regulatory effect of DRDs on B cells has not been determined.

Methods: This study explored the expression of DRDs on B-cell subsets from SLE patients and healthy individuals. The effects of D1-like receptor on B-cell activation and differentiation were further explored using D1-like receptor agonists or antagonists. RNA-seq and bioinformatics analyses were used to identify specific molecular mechanisms involved.

Results: The D1-like DRDs on B cells of SLE patients were highly expressed compared with those of healthy controls (HCs). D1-like receptor agonist treatment exacerbated lupus-like symptoms in pristane-induced lupus-like mice, while D1-like receptor antagonists alleviated the lupus-like phenotypes. Inhibition of D1-like receptor signals impeded B-cell differentiation, while activation of D1-like receptor signals could promote B cell differentiation. Further RNA-seq confirmed that PTGS2, a gene related to B-cell differentiation, was up-regulated once the D1-like receptor signals were activated, while BMP6 and IL-24 were up-regulated once the D1-like receptor signals were inhibited.

Conclusion: D1-like receptors probably promote B-cell differentiation through the PTGS2/PRDM1 pathway.