Puerarin protects fibroblasts against mechanical stretching injury through Nrf2/TGF-β1 signaling pathway

Abstract

Introduction and hypothesis: Stress urinary incontinence (SUI) is the most common form of urinary incontinence in women, which affects women's quality of life worldwide. Mechanical injury of the pelvic floor may disrupt the pelvic supportive tissues and connections via the remodeling of extracellular matrix (ECM), which is supposed to be one of the main pathological mechanisms of SUI.

Methods: The SUI mouse model was established using vaginal distension (VD). Leak point pressure (LPP), maximum cystometric capacity (MCC), collagen, Nrf2 and TGF-β1 in the anterior vaginal wall were measured in either wild-type or Nrf2-knockout (Nrf2^-/^-) female C57BL/6 mice with or without puerarin treatment. Then, the mechanical stretching (MS) loaded on L929 cells was generated by a four-point bending device. mTGF-β1 or LY2109761 (an inhibitor of TGF-β1) was used to verify the protective effect of puerarin after Nrf2 knockdown or overexpression.

Results: The collagen content of the anterior vaginal tissues in VD mice and LPP and MCC was decreased significantly. Besides, the expression levels of Nrf2, TGF-β1, collagen I and collagen III of MS group were downregulated in L929 cells. Puerarin pretreatment could reverse mechanical injury-induced collagen downregulation and Nrf2/TGF-β1 signaling inhibition. Moreover, both LY2109761 pretreatment and Nrf2 knockdown could attenuate the protective effect of puerarin in the mechanical injury-induced ECM remodeling, whereas exogenous TGF-β1 could counteract the effect of Nrf2 downregulation.

Conclusions: Puerarin protected fibroblasts from mechanical injury-induced ECM remodeling through the Nrf2/TGF-β1 signaling pathway. This might be a new strategy for the treatment of SUI.

Keywords: Extracellular matrix; Mechanical stretching; Nrf2; Puerarin; TGF-β1.