Paeonol attenuated vascular fibrosis through regulating Treg/Th17 balance in gut microbiota-dependent manner

OBJECTIVE Atherosclerosis(AS)is a chronic inflammatory disease characterized by the accumulation of lipids,vascular fibrosis,and inflammation.Paeonol(Pae)is a natural phenolic compounds isolated from a traditional Chinese medicine,Cortex Moutan,which exhibits anti-AS effects.Our previous work demonstrated that gut microbiota plays an important role during AS treatment as it affects the efficacy of Pae.However,the mechanism of Pae in protecting against vascular fibrosis as related to gut microbiota has yet to be elucidated.To investigate the anti-fibrosis effect of Pae on AS mice and demonstrate the underlying gut microbiota-dependent mechanism.METHODS ApoE-/-mice were fed with high-fat-diet(HFD)to replicate the AS model.HE and Masson staining were used to observe the plaque formation and collagen deposition.Gut microbiota alteration and short-chain fatty acids(SCFAs)production were analyzed through 16S rRNA sequencing and LC-MS/MS.The frequency of immune cells in spleen were phenotyped by flow cytometry.The mRNA expression of aortic inflammatory cytokines were detected by qRT-PCR.The protein expression of LOX and fibrosis related indicators were examined by Western blotting.RESULTS Pae restricted the development of AS and collagen deposition.Notably,the anti-fibrosis effect of Pae was achieved by regulating the gut microbiota.16S rRNA sequencing and LC-MS/MS data indicated that the relative abundance of SCFAs-producing bacteria and SCFAs production was increased.Additionally,Pae administration selectively up-regulated the frequency of regulatory T(Treg)cells as well as down-regulated the ratio of T helper type 17(Th17)cells in the spleen of AS mice,improving the Treg/Th17 balance.In addition,as expected,Pae intervention significantly down-regulate the mRNA expression levels of pro-inflammatory cytokines IL^(-1)β,IL-6,TNF-αand IL^(-1)7 in the aorta tissue,up-regulate the levels of anti-inflammatory factor IL^(-1)0,a marker of Treg cells.Finally,Pae′s intervention in the gut microbiota resulted in the restoration of the balance of Treg/Th17,which indirectly down-regulated the protein expression level of LOX and fibrosis-related indicators(MMP-2/9 and collagenⅠ/Ⅲ).CONCLUSION Pae attenuates vascular fibrosis in a gut microbiota-dependent manner.The underlying protective mechanism is associated with the improved Treg/Th17 balance in spleen mediated through the increased microbiota-derived SCFAs production.

Transforming growth factor-β1 involved in urotensin Ⅱ-induced phenotypic differentiation of adventitial fibroblasts from rat aorta

Background Urotensin Ⅱ （UⅡ） is a new vasoconstrictive peptide that may activate the adventitial fibroblasts.Transforming growth factor-β1 （TGF-β1） is an important factor that could induce the phenotypical transdifferentiation of adventitial fibroblasts. This study aimed to explore whether TGF-β1 is involved in UⅡ-induced phenotypic differentiation of adventitial fibroblasts from rat aorta.Methods Adventitial fibroblasts were prepared by the explant culture method. TGF-β1 protein secretion from the cells was determined by enzyme-linked immunosorbent assay （ELISA）. The mRNA and protein expression of α-smooth nuscle actin （α-SM-actin）, the marker of phenotypic differentiation from fibroblasts to myofibroblasts, were determined using real-time quantitative RT-PCR （real-time RT-PCR） and Western blotting, respectively.Results UⅡ stimulated the secretion of TGF-β1 in cultured adventitial fibroblasts in a time-dependent manner. The secretion reached a peak at 24 hours, was higher by 69.8% （P ＜0.01）, than the control group. This effect was also concentration dependent. Maximal stimulation was reached at 10-8 mol/L of UⅡ （P ＜0.01）, which was increased by 59.9%,compared with in the control group （P ＜0.01）. The secretion of TGF-β1 induced by UⅡ was significantly blocked by SB-710411 （10-7 mol/L）, a specific antagonist of UⅡ receptor. In addition, both UⅡ （10-8 mol/L） and TGF-β1 significantly stimulated α-SM-actin mRNA and protein expression. Moreover, the α-SM-actin induced by UⅡ was inhibited by the specific neutralizing antibody （20 μg/ml） of TGF-β1, while the α-SM-actin expression stimulated by TGF-β1 （20 ng/ml）was inhibited by SB-710411 （10-7 mol/L）, the UⅡ receptor antagonist.Conclusion This study suggests that UⅡ could induce TGF-β1 secretion in adventitial fibroblasts via UT activation, and TGF-β1 might be involved in phenotypic differentiation from adventitial fibroblasts into myofibroblasts induced by UⅡ, and TGF-β1 signaling might be one of the important pathways by which UⅡ is involved in vascular fibrosis.