[Mechanism of Buyang Huanwu Decoction and Didang Decoction in treatment of chronic kidney disease based on ATF6/TXNDC5-regulated "macrophage-myofibroblast transformation" pathway].

This study aims to investigate the mechanism of Buyang Huanwu Decoction and Didang Decoction regulating activating transcription factor 6(ATF6)/thioredoxin domain containing 5(TXNDC5) signaling axis to mediate macrophage-myofibroblast transformation(MMT) pathway in chronic kidney disease. Twenty-four SPF SD rats were randomly divided into a blank group(n=9) and a modeling group(n=15). The chronic kidney disease model was established by gavage of adenine for 28 days. After successful modeling, the modeling group was randomly divided into a model group and a Buyang Huanwu Decoction and Didang Decoction group. The blank group and the model group were treated with the same volume of physiological saline, and the Buyang Huanwu Decoction and Didang Decoction group was treated by gavage of Buyang Huanwu Decoction and Didang Decoction(13.8 g·kg~(-1)) daily for 28 days. The 24 h urine was collected on the 28th and 56th days of the experiment, and the 24 h urine protein content was detected. After the last administration, all rats were weighed and anesthetized. The kidney weight of the rats was measured, and the renal index was evaluated. The content of serum creatinine(Scr) and blood urea nitrogen(BUN) was detected by an automatic biochemical analyzer, and the concentrations of serum interleukin-1β(IL-1β), tumor necrosis factor-α(TNF-α), interleukin-10(IL-10), and arginase-1(Arg-1) were detected by enzyme-linked immunosorbent assay. The pathological changes of renal tissue were observed by hematoxylin-eosin staining and Masson staining, and the collagen volume fraction(CVF) was calculated. Transmission electron microscopy(TEM) was used to observe the ultrastructural changes of mitochondria in rat renal tissue cells. Multiplex immunofluorescence was used to detect the co-localization of cluster of differentiation 68(CD68)~+α-smooth muscle actin(α-SMA)~+ and CD68~+α-SMA~+collagen type Ⅰ(COL-Ⅰ)~+ in the kidney. Moreover, real-time quantitative polymerase chain reaction was utilized to quantify the mRNA levels of ATF6, TXNDC5, transforming growth factor-β1(TGF-β1), and α-SMA in renal tissue, and the protein levels of ATF6, TXNDC5, and TGF-β1 in the renal tissue were determined by Western blot. The results showed that compared with the blank group, the model group showed a significantly decreased body weight and significantly increased 24 h urine protein, kidney weight, and renal index. The serum levels of Scr, BUN, IL-1β, and TNF-α were significantly increased, while the serum levels of IL-10 and Arg-1 were significantly decreased. Furthermore, the pathological changes of renal tissue were severe, and CVF was significantly increased. The mitochondrial structure of kidney tissue was disordered. High expression of CD68~+α-SMA~+ cells was found in renal tissue, and CD68~+α-SMA~+ MMT cells significantly co-expressed COL-Ⅰ. Finally, the expression of α-SMA mRNA in renal tissue was significantly increased, and the mRNA and protein expression levels of ATF6, TXNDC5, and TGF-β1 in renal tissue were significantly increased. Buyang Huanwu Decoction and Didang Decoction significantly increased the body weight and the levels of IL-10 and Arg-1 in the serum of chronic kidney disease rats and significantly decreased the content of 24 h urine protein, kidney weight, renal index, and the serum levels of Scr, BUN, IL-1β, and TNF-α. The pathological damage of renal tissue was significantly improved, and the CVF was significantly decreased. The ultrastructural damage of renal tissue was significantly improved, as evidenced by TEM. Moreover, Buyang Huanwu Decoction and Didang Decoction decreased the expression of CD68~+α-SMA~+ and CD68~+α-SMA~+COL-Ⅰ~+ in renal tissue and down-regulated the expression level of α-SMA mRNA and the mRNA and protein levels of ATF6, TXNDC5, and TGF-β1 in renal tissue. In conclusion, Buyang Huanwu Decoction and Didang Decoction can regulate ATF6/TXNDC5 signaling pathway, down-regulate TGF-β1 expression, reduce the occurrence of MMT in chronic kidney disease, reduce renal fibrosis, and improve renal injury, so as to play a protective role in kidney.