Protective effects of SKLB023 on a mouse model of unilateral ureteral obstruction by the modulation of gut microbiota

Abstract

Renal interstitial fibrosis is the common pathway underlying the progression of chronic kidney disease (CKD) to end-stage renal disease (ESRD) and the corresponding therapies are limited. Quantitative and qualitative alterations in gut microbiota are noted in patients with CKD and ESRD. In our previous study, SKLB023 exhibited antifibrotic effects by interfering TGF-β1/Smad3 signaling in obstructive nephropathy. However, it remained unclear that oral administration of SKLB023 drives the alteration of gut microbiota to attenuate renal fibrosis. In the study, the marked inflammation and interstitial fibrosis were found in the kidney tissues of unilateral ureteral obstruction (UUO) mice. While treatment with SKLB023 significantly alleviated renal interstitial fibrosis and reduced serum proinflammatory cytokines TNF-α, IL-6 levels. Importantly, SKLB023 derived the modulation of gut microbiota with the increasing similarity between the composition of gut microbiota in the control and UUO. The number of Turicibacter and Candidatus_Arthromitus was significantly decreased following UUO surgery and recovered by SKLB023, which positively correlated with pro-inflammatory cytokine expression. These results indicated the potential relationship between the antifibrotic benefits of SKLB023 and gut microbiota alteration, which provided new insights into drug therapy via gut microbiota modulation in obstructive nephropathy.

Fig. 1. The chemical structure of SKLB023 (A) and histopathological finding of renal tissues. (B) UUO mice exhibited marked interstitial fibrosis in renal tissue stained with HE and Masson's trichrome. (C and E) SKLB023 inhibited the expression of fibrosis maker α-SMA in UUO mice. (D) Treatment with SKLB023 significantly reduced interstitial fibrosis.

Fig. 2. Microbiota changes in the composition of UUO mice by SKLB023. The rarefaction curves of alpha diversity by Shannon index of (A) each sample and (B and C) each group. (D) Venn diagram of OTUs in the three groups. (E) Multiple sample PCA analysis. (F) Multiple sample PCoA analysis.

Fig. 3. The heatmap of each sample (A), each group (B) and circus (C) on the basis of the most modified species at genus level.

Fig. 4. Effects of SKLB023 on gut microbiota relative proportion in UUO mice at different levels. The main microbiotas and their relative proportions in different groups at phylum level (A), family level (D) and genus level (G). Data are presented as the means at phylum level (B), family level (E) and genus level (H). The top fifteen microbiotas and their relative proportions in different groups at phylum level (C), family level (F) and genus level (I). *p < 0.05 among the three groups.

Fig. 5. Difference in dominant microorganisms between groups. (A) Cladogram. (B) Distribution histogram based on LDA.

Fig. 6. Plasma levels of TNF-α and IL-6 in different groups (A). Spearman's correlation between the identified microbiota at different levels ((B) phylum, (C) family, and (D) genus) and TNF-α and IL-6. The color of the squares represents the R-value of Spearman's correlation. *p < 0.05, **p < 0.01, ***p < 0.001.