Frontiers in Immunology (Apr 2023)

Klf4 protects thymus integrity during late pregnancy

  • Lucyle Depoërs,
  • Maude Dumont-Lagacé,
  • Maude Dumont-Lagacé,
  • Vincent Quoc-Huy Trinh,
  • Vincent Quoc-Huy Trinh,
  • Chloé Houques,
  • Caroline Côté,
  • Jean-David Larouche,
  • Sylvie Brochu,
  • Claude Perreault

DOI
https://doi.org/10.3389/fimmu.2023.1016378
Journal volume & issue
Vol. 14

Abstract

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Pregnancy causes abrupt thymic atrophy. This atrophy is characterized by a severe decrease in the number of all thymocyte subsets and qualitative (but not quantitative) changes in thymic epithelial cells (TECs). Pregnancy-related thymic involution is triggered by progesterone-induced functional changes affecting mainly cortical TECs (cTECs). Remarkably, this severe involution is rapidly corrected following parturition. We postulated that understanding the mechanisms of pregnancy-related thymic changes could provide novel insights into signaling pathways regulating TEC function. When we analyzed genes whose expression in TECs was modified during late pregnancy, we found a strong enrichment in genes bearing KLF4 transcription factor binding motifs. We, therefore, engineered a Psmb11-iCre : Klf4lox/lox mouse model to study the impact of TEC-specific Klf4 deletion in steady-state conditions and during late pregnancy. Under steady-state conditions, Klf4 deletion had a minimal effect on TEC subsets and did not affect thymic architecture. However, pregnancy-induced thymic involution was much more pronounced in pregnant females lacking Klf4 expression in TECs. These mice displayed a substantial ablation of TECs with a more pronounced loss of thymocytes. Transcriptomic and phenotypic analyses of Klf4-/- TECs revealed that Klf4 maintains cTEC numbers by supporting cell survival and preventing epithelial-to-mesenchymal plasticity during late pregnancy. We conclude that Klf4 is essential for preserving TEC’s integrity and mitigating thymic involution during late pregnancy.

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