KuJiang GanLuoYin Alleviates Hypertensive Vascular Injury and Modulates FMO2/FTO/m⁶A Signaling

Background: Hypertension-induced vascular injury involves endothelial dysfunction, inflammation, and oxidative stress, leading to vascular remodeling and cardiovascular complications. Flavin-containing monooxygenase 2 (FMO2) has been implicated in redox regulation, but its role in hypertensive vascular injury remains unclear. This study investigated whether KuJiang GanLuoYin (KJGLY) protects against hypertensive vascular injury and whether FMO2-associated Fat mass and obesity-associated protein (FTO)/N6-methyladenosine (m⁶A) signaling is involved. Methods: Spontaneously hypertensive rats (SHRs) were treated with KJGLY for eight weeks. Blood pressure, vascular remodeling, inflammation, oxidative stress, and global m⁶A RNA methylation were assessed. Integrated metabolomic and proteomic analyses were performed to identify treatment-associated molecular alterations and candidate proteins. AAV9-mediated FMO2 knockdown in SHRs and gain- and loss-of-function approaches in angiotensin II (Ang II)-stimulated human umbilical vein endothelial cells were used to examine the functional involvement of FMO2. Ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF/MS)-based chemical profiling and High-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) quantification were performed to characterize the major constituents of KJGLY. Results: KJGLY significantly reduced blood pressure and alleviated vascular remodeling in SHRs. Metabolomic and proteomic analyses revealed treatment-associated alterations in inflammatory and lipid metabolic pathways and identified FMO2 as a treatment-responsive candidate. KJGLY restored FMO2 expression, reduced FTO abundance and NF-κB activation, increased global m⁶A levels, and attenuated inflammatory and oxidative stress responses in hypertensive aortas. Conversely, AAV9-mediated FMO2 knockdown aggravated vascular injury, enhanced inflammation and oxidative stress, reduced global m⁶A levels, and increased NF-κB activation. Co-immunoprecipitation showed an association between FMO2 and FTO, and MeRIP-qPCR indicated that FMO2 manipulation altered m⁶A enrichment of VCAM-1 mRNA. In Ang II-stimulated endothelial cells, linarin, the most abundant quantified constituent of KJGLY, partially recapitulated the cellular effects of KJGLY, including restoration of FMO2/FTO-associated signaling and attenuation of inflammatory activation. Conclusions: These findings support a functional role for FMO2 in hypertensive vascular injury and suggest that FMO2-associated modulation of FTO/m⁶A signaling may contribute to the vascular protective effects of KJGLY. Linarin recapitulated key protective effects in vitro, although its in vivo contribution to the formula remains to be determined.