PD-L1⁺ Regulatory B Cells from Rheumatoid Arthritis Patients Have Impaired Function in Suppressing IFN-ү and IL-21...

Area of Science:

• Immunology
• Autoimmune Diseases
• Cell Biology

Background:

• Rheumatoid arthritis (RA) is a systemic autoimmune disease driven by immune cell dysregulation.
• Regulatory B cells (Breg) modulate autoimmune responses by suppressing T-cell activity.
• The PD-1/PD-L1 pathway is crucial for immune regulation and may be impaired in autoimmune conditions.

Purpose of the Study:

• To investigate the role of programmed death-ligand 1 (PD-L1) expressing Breg cells in rheumatoid arthritis.
• To determine if PD-L1+ Breg cells can downregulate T-helper (Th) cell immune responses in healthy individuals and RA patients.
• To explore the potential of modulating PD-L1+ Breg cells for RA therapy.

Main Methods:

• Isolation of T and B cells from peripheral blood of healthy volunteers and RA patients using magnetic cell sorting and fluorescence-activated cell sorting.
• Induction of PD-L1 high expressing Breg cells using CpG and CD40L stimulation.
• Detection of cytokine production (IFN-γ, IL-21) in CD4+ Th cells via intracellular flow cytometry.
• Co-culture experiments to assess the suppressive capacity of induced PD-L1+ Breg cells on autologous Th cells.

Main Results:

• The frequency of PD-L1 high Breg cells was significantly lower in all B-cell subsets from RA patients compared to healthy controls.
• Induced PD-L1+ Breg cells from healthy individuals effectively inhibited IFN-γ and IL-21 production by Th cells.
• RA patient-derived PD-L1+ Breg cells, with their lower frequency, failed to suppress Th cell cytokine production.

Conclusions:

• A deficiency in PD-L1 expressing Breg cells and their suppressive function is observed in rheumatoid arthritis patients.
• In vitro induction of PD-L1 expression on B cells can restore Breg cell suppressive capacity.
• Modulating PD-L1+ Breg cells presents a potential novel therapeutic strategy for rheumatoid arthritis.