Semaphorin 3A alters endothelial cell immunogenicity by regulating Class II transactivator activity circuits

Area of Science:

• Immunology
• Transplantation Biology
• Cell Signaling

Background:

• Endothelial cells (ECs) are critical in allogeneic immune responses during transplantation.
• Semaphorin 3A (Sema3A) is known to affect EC growth, but its immunomodulatory role was unexplored.

Purpose of the Study:

• To investigate the impact of Semaphorin 3A (Sema3A) on endothelial cell (EC) immunogenicity.
• To explore the relationship between Sema3A, CIITA, HLA-DR, and T-cell activation in the context of transplantation.

Main Methods:

• ECs were transduced with a lentiviral vector for transgene expression.
• Nonmodified ECs were stimulated with recombinant Sema3A.
• mRNA and protein levels of CIITA, HLA-DR, and Sema3A receptors were quantified.
• Sema3A levels in kidney transplant patients' sera were measured using ELISA.

Main Results:

• Sema3A stimulation upregulated transgene expression and CIITA levels in ECs.
• Sema3A enhanced CIITA expression, leading to increased HLA-DR and CD4+ T-cell proliferation.
• A positive feedback loop was observed between CIITA and Sema3A receptor expression.
• Higher Sema3A serum levels were detected in patients experiencing organ rejection.

Conclusions:

• Sema3A signaling in ECs elevates CIITA and HLA-DR, promoting CD4+ T-cell activation.
• This mechanism has significant implications for understanding and potentially managing tissue and organ transplant rejection.