BTLA Expression and Function Are Impaired on SLE B Cells

Area of Science:

• Immunology
• Autoimmunity
• Cell Biology

Background:

• B- and T-lymphocyte attenuator (BTLA/CD272) is an inhibitory checkpoint molecule on lymphocytes.
• Previous studies indicated defective T cell BTLA function in systemic lupus erythematosus (SLE).
• The role of BTLA on B cells in SLE, a condition with B cell abnormalities, remains largely unknown.

Purpose of the Study:

• To investigate the expression and function of BTLA on B cells in SLE patients.
• To explore the relationship between BTLA expression and disease markers in SLE.
• To assess the potential therapeutic implications of targeting BTLA or related pathways in SLE.

Main Methods:

• Peripheral blood mononuclear cells (PBMCs) from SLE patients and healthy donors were analyzed for BTLA expression on B cells.
• B cells were stimulated with anti-BTLA antibodies or spleen tyrosine kinase (SYK) inhibitors.
• Differentiation and activation markers (CD71, PD-1, CD86) were assessed.

Main Results:

• Reduced BTLA expression was observed on naive B cells (CD27-IgD+) from SLE patients, correlating with anti-dsDNA antibody titers and monocyte SIGLEC-1/CD169 expression.
• BTLA engagement inhibited plasmablast and memory B cell induction via CpG/TLR9 activation in healthy B cells but not in SLE B cells.
• SYK inhibition mimicked BTLA activity in vitro, suggesting a functional link.

Conclusions:

• Reduced BTLA expression and impaired function on SLE B cells contribute to aberrant immune responses.
• SYK inhibition presents a potential therapeutic avenue to overcome BTLA deficiency in SLE B cells.
• Further studies are warranted to evaluate SYK inhibition as a therapeutic principle in SLE.