Treatment with rapamycin can restore regulatory T-cell function in IPEX patients

Area of Science:

• Immunology
• Genetics
• Cell Biology

Background:

• Immune-dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX) syndrome is a lethal autoimmune disorder caused by FOXP3 mutations, impairing regulatory T (Treg) cell function.
• Current treatments like hematopoietic stem cell transplantation are limited, and other immunosuppressants offer poor long-term survival.
• Rapamycin shows promise by suppressing peripheral T cells while sparing Treg cells, but its mechanism in IPEX syndrome is unclear.

Observation:

• This study investigated the cellular and molecular mechanisms of rapamycin's benefit in 6 patients with IPEX syndrome and various FOXP3 mutations.
• Researchers analyzed Treg cell phenotype, function, and gene expression in patients undergoing rapamycin treatment.
• Methods included flow cytometry, in vitro suppression assays, and droplet-digital PCR.

Findings:

• Rapamycin treatment partially restored Treg cell function in IPEX patients, leading to clinical and histologic improvements.
• This Treg restoration was independent of FOXP3 expression or Treg cell frequency.
• Key molecules TNFRSF18 and EBI3 were upregulated in treated patients' Treg cells, and their inhibition partially reversed rapamycin-conditioned Treg suppression.

Implications:

• Rapamycin exerts beneficial effects in IPEX syndrome through a FOXP3-independent mechanism.
• This finding offers a potential therapeutic strategy for immune dysregulation in IPEX syndrome.
• Understanding this pathway may lead to improved treatments for autoimmune diseases.