Mesenchymal stem cell-mediated T cell suppression occurs through secreted galectins

Area of Science:

• Immunology
• Cell Biology
• Biochemistry

Background:

• Human galectins play roles in various biological and pathological processes.
• Galectin-3 was previously identified as modulating the immunosuppressive potential of mesenchymal stem cells (MSCs).

Purpose of the Study:

• To investigate the expression profiles and activities of other galectins in MSCs.
• To elucidate the role of galectins in MSC-mediated T cell suppression.

Main Methods:

• Analysis of galectin mRNA and protein expression in MSCs.
• Use of galectin-specific siRNAs to inhibit gene expression.
• Assessment of T cell suppression assays.
• Application of a competitive galectin binding inhibitor (β-lactose).

Main Results:

• MSCs constitutively express galectins-1, -3, and -8 at mRNA and protein levels.
• Galectins-1 and -3 are secreted and cell surface-associated, unlike galectin-8.
• Knockdown of galectins-1 and -3 significantly impaired MSC-mediated T cell suppression.
• β-lactose treatment restored T cell alloresponsiveness, indicating an extracellular mechanism.

Conclusions:

• Secreted galectins-1 and -3 are key mediators of MSC-induced T cell suppression.
• These findings suggest potential therapeutic applications for recombinant galectin-1 and/or -3 in treating inflammatory conditions such as graft versus host disease and autoimmune disorders.