Fibroblast heterogeneity in Peutz-Jeghers syndrome: identifying the polyp-driving subset†.

Peutz-Jeghers syndrome (PJS) is a rare autosomal dominant disorder caused by germline mutations in STK11, and is characterized by gastrointestinal hamartomatous polyps, the recurrent development of which significantly impacts patients' quality of life. While stromal cells have been implicated in PJS polyp formation, their specific characteristics remain unclear. Domènech-Moreno et al identify polyp-enriched crypt top fibroblasts (pCTFs) as the pathogenic fibroblast population and demonstrate that interleukin (IL)-11, a major secretory factor produced by these cells, serves as a critical mediator linking STK11 deficiency to epithelial proliferation. The study reveals that Stk11 loss triggers IL-11 expression, which in turn reinforces the pathogenic pCTF phenotype through autocrine signaling, forming a feedforward loop. Importantly, IL-11 neutralization significantly reduces polyp formation in a faithful mouse model, providing strong preclinical evidence for therapeutic translation. This work represents a significant advance in our understanding of PJS pathogenesis and establishes IL-11 as a promising therapeutic target. Future investigations into the effects of IL-11 neutralization on established polyps will further refine the translational potential of these findings for preventive intervention strategies. © 2026 The Pathological Society of Great Britain and Ireland.