Kidney fibrosis is a common fate of chronic kidney diseases (CKDs), eventually leading to renal dysfunction. Yet, no effective treatment for this pathological process has been achieved. During the bioassay‐guided chemical investigation of the medicinal plant Wikstroemia chamaedaphne , a daphne diterpenoid, daphnepedunin A ( DA ), is characterized as a promising anti‐renal fibrotic lead. DA shows significant anti‐kidney fibrosis effects in cultured renal fibroblasts and unilateral ureteral obstructed mice, being more potent than the clinical trial drug pirfenidone. Leveraging the thermal proteome profiling strategy, cell division cycle 42 (Cdc42) is identified as the direct target of DA . Mechanistically, DA targets to reduce Cdc42 activity and down‐regulates its downstream phospho‐protein kinase Cζ(p‐PKCζ)/phospho‐glycogen synthase kinase‐3β (p‐GSK‐3β), thereby promoting β‐catenin Ser33/37/Thr41 phosphorylation and ubiquitin‐dependent proteolysis to block classical pro‐fibrotic β‐catenin signaling. These findings suggest that Cdc42 is a promising therapeutic target for kidney fibrosis, and highlight DA as a potent Cdc42 inhibitor for combating CKDs.

Background: Urinary tract infections (UTIs) rank among the most prevalent infectious diseases globally, with recurrent UTIs (rUTIs) posing substantial therapeutic challenges due to the lack of durable protective immunity. While trained immunity augments innate immune responses, its induction and functional significance in bladder-resident group 3 innate lymphoid cells (ILC3s) remain unknown. This study investigates whether ILC3s develop trained immunity following uropathogenic Escherichia coli (UPEC) exposure and how they contribute to mucosal defense against rUTIs. Methods: The ILC3 counts were detected in bladder sections from UTI patients and health controls (HC). A recurrent UTI mouse model was established through primary and secondary urethral UPEC inoculation. Bacterial loads in tissues were assessed, and single-cell suspensions were analyzed via flow cytometry. Bladder naïve- and UPEC-trained ILC3s were adoptively transferred, with evaluations of histopathology, epithelial barrier function, inflammation, and antimicrobial peptides. The in vitro ILC3 cell line MNK-3 was detected for IL-17A and IL-22 production following primary and secondary UPEC lysate stimulation. Results: We demonstrate that primary UPEC infection triggers ILC3 expansion in both human and murine bladders. Upon secondary challenge, these ILC3s develop trained immunity, characterized by enhanced proliferation, amplified IL-17A and IL-22 production, and improved pathogen clearance. Mechanistically, trained ILC3s reinforce urothelial barrier integrity through upregulation of antimicrobial peptides (Reg3b/Reg3g) and attenuate inflammatory pathology by suppressing pro-inflammatory cytokines (IL-6, TNF-α). Conclusions: We uncover an endogenous defense mechanism wherein UPEC primes bladder ILC3s via trained immunity, enabling amplified IL-17A- and IL-22-mediated protection against recurrent infections. These findings establish ILC3-trained immunity as a novel conceptual foundation, providing a basis for developing immunotherapies against rUTIs.