Mechanistic Insights into Kaempferol's Therapeutic Effects on Postmenopausal Osteoporosis: A Proteomic and Experimental Validation in Ovariectomized Rats
Authors: Zhang Chi , Huang Xiaoqing , Qin Baijun , Zhang Xiaoyun , Liang Zhou , Pu Zhanglin , Xu Zhiwei , Wu Xiaofei , Liu Fei , Yang Lei , Chen Feng , Yan Qian 
Published: January 2025

Background:
Postmenopausal Osteoporosis (PMOP) is characterized by decreased
bone mass and deterioration of bone microarchitecture, leading to increased fracture risk. Current
treatments often have adverse effects, necessitating safer alternatives. Kaempferol, a flavonoid
identified as a key active component of the traditional Chinese medicine Yishen Gushu
formula, has shown promise in improving bone health, but its mechanisms in PMOP treatment
remain unclear.

Objective:
The aim of this study was to investigate the therapeutic effects and underlying mechanisms
of kaempferol in the treatment of PMOP.

Methods:
A bilateral ovariectomized (OVX) rat model was established to simulate PMOP. Sixty
female Sprague-Dawley rats were divided into six groups: Sham operation, OVX control, OVX
with alendronate (ALN), and OVX with kaempferol at doses of 10, 20, and 40 mg/kg. Treatments
were administered orally once daily for 12 weeks. Assessments included Bone Mineral
Density (BMD), trabecular microarchitecture via histopathology, organ morphology, organ indices,
and serum levels of bone metabolism markers (TRACP-5b, BALP, ALP, Ca, P, and Fe) as
well as liver and kidney function indicators (ALT, AST, CREA, and urea). Tandem Mass Tag
(TMT) quantitative proteomics and bioinformatics analyses were conducted on femur samples to
identify differentially expressed proteins (DEPs). Key DEPs were validated using parallel reaction
monitoring (PRM), immunohistochemistry, and molecular docking.

Results:
Kaempferol significantly improved BMD and enhanced trabecular microarchitecture in
OVX rats in a dose-dependent manner, comparable to ALN, without causing hepatic, renal, or estrogen-
like side effects. Serum bone metabolism markers were normalized with kaempferol treatment.
Proteomic analysis identified 902 DEPs associated with kaempferol treatment, involved in
processes such as bone remodeling, skeletal system development, and osteoclast function. Key signaling
pathways affected included NF-κB, PI3K-AKT, and HIF-1. Notably, kaempferol downregulated
five key DEPs—Rac2, Ddb1, Cdc42, Rpl19, and Hist2h4-in the femur, which are crucial
for osteoclast resorptive activity, migration, adhesion, and cell cycle progression.

Conclusion:
Kaempferol exerts therapeutic effects on PMOP by inhibiting key proteins involved
in osteoclast function, thereby reducing bone resorption and promoting bone health. These findings
suggested that kaempferol is a potential safer alternative for PMOP treatment. Further research
is recommended to explore its clinical applications and elucidate detailed mechanisms.

conclusion:
Kaempferol may reduce osteoclast resorptive activity, migration, adhesion ability, and polarization level, increase apoptosis, and slow the cell cycle of osteoclasts by inhibiting Hist2h4, Cdc42, and Rac2 protein expression, thus exerting an anti-PMOP effect.

other:
None.