Renal Interstitial Fibrosis Is Reduced in High-Fat Diet-Induced Obese Pigs following Renal Denervation from the Intima and Adventitia of the Renal Artery

Abstract

Background: This study aims to compare whether 2 different routes of renal denervation (RDN) from the intima and adventitia of the renal artery can reduce renal fibrosis in a pig model of hypertension induced by a high-fat diet and to explore possible molecular mechanisms. Methods: Twenty-four Bama miniature pigs were randomly divided into a control group (normal diet, n = 6) or a hypertension model group (high-fat diet, n = 18). The model group was randomly divided into the intima-RDN group (n = 6), the adventitia-RDN group (n = 6), or the renal arteriography-only group (sham group, n = 6). All animals were fed separately. The model group was fed a high-fat diet after the operation, and the control group was fed conventionally for 6 months. After 6 months, renal artery angiography was performed again to observe the condition of the renal arteries, after which all animals were euthanized. The blood pressure and blood biochemical results of each group were evaluated 6 months after the operation; kidney tissue morphology and collagen fiber content were examined by hematoxylin-eosin staining and Masson staining; superoxide dismutase activity and the malondialdehyde content of kidney tissue were assessed by a biochemical enzyme method; the protein expression level of transforming growth factor-β 1 (TGF-β1), α-smooth muscle actin (α-SMA), and Smad3 was assessed by Western blot, and electron microscopy was used to examine changes in the kidney microstructure. Results: After 6 months of a high-fat diet, the blood lipid levels of the model group were significantly higher compared to baseline and to that of the control group during the same period (all showed p < 0.05); the blood lipid levels of the control group did not change significantly from baseline (p > 0.05). The degree of glomerular damage caused by hyperlipidemia in the intima-RDN group and the adventitia-RDN group was significantly lower than that of the sham and control groups, and the renal fibrosis area percentage was also significantly lower (p < 0.05). Electron microscopy showed that both the intima-RDN group and the adventitia-RDN group had a more even distribution of chromosomes and less mitochondrial swelling compared with the sham group. Conclusion: RDN from the adventitia of the renal artery and RDN from the intima of the renal artery have the similar advantages of delaying high-fat-induced renal fibrosis. The antifibrotic effect of RDN may be related to inhibition of the TGF-β1/Smad3 pathway.