TLR9-induced miR-155 and Ets-1 decrease expression of CD1d on B cells in SLE

Area of Science:

• Immunology
• Autoimmunity
• Molecular Biology

Background:

• B cells present lipid antigens to invariant natural killer T (iNKT) cells, crucial for autoimmune tolerance.
• This process is impaired in systemic lupus erythematosus (SLE), potentially due to inflammation-induced reduction of CD1d expression on B cells.

Purpose of the Study:

• To elucidate the mechanisms by which inflammation regulates CD1d expression on B cells in SLE.
• To investigate the role of microRNA-155 (miR-155) and Ets-1 in this regulatory process.

Main Methods:

• Analysis of CD1d surface expression on B cells from SLE and control mice.
• Stimulation of inflammatory responses via TLR9 and assessment of CD1d levels.
• Investigation of miR-155 targeting of CD1d 3'-untranslated region (3'-UTR).
• Evaluation of Ets-1's effect on CD1d gene transcription.

Main Results:

• Decreased surface CD1d expression on B cells from SLE mice.
• TLR9 activation reduced both membrane and total CD1d levels on B cells.
• miR-155 negatively correlated with CD1d expression and directly targeted CD1d's 3'-UTR upon TLR9 activation.
• miR-155-mediated inhibition of CD1d impaired B cell antigen presentation to iNKT cells.
• Ets-1 directly regulated CD1d gene expression transcriptionally.

Conclusions:

• Inflammation, via TLR9 and miR-155, decreases CD1d expression on B cells in SLE, compromising iNKT cell function.
• Ets-1 also plays a role in regulating CD1d expression.
• Inhibition of inflammation may represent a therapeutic strategy to enhance CD1d expression and ameliorate SLE by modulating iNKT cell activity.