Figure 1 Icariin attenuates renal function and histological damage in UUO mice. (A) The chemical structure of icariin. (B) Experiment outline. (C) Weight changes after 14 days of UUO surgery. (D-E) Serum BUN and Cr levels in different group. (G) Representative images of H&E and Masson’s staining, and quantitative assessment of renal injury (F) and fibrosis (H). (I) Western blot analysis of collagen I and α-SMA expression in the kidney from different groups. BUN, blood urea nitrogen; Cr, creatinine. * p < 0.05, ** p < 0.01.
Icariin alleviated inflammatory responses and oxidative stress in UUO mice.
To explore the underlying mechanism of icariin therapy, transcriptome sequencing was applied. According to results of the Gene Ontology (GO) term analysis between the sham and UUO mice, the differentially expressed genes exhibited strong enrichment in inflammatory response and oxidoreductase activity (Figure 2A). Considering that inflammation and oxidative stress are well-documented contributors in the development of interstitial fibrosis, the present research centered on the impact of icariin on pivotal genes within the enriched gene sets related to inflammatory response and oxidoreductase activity. As shown in Figure 2B, icariin reduced inflammatory response-related gene expression profiles. In addition, the mRNA expression of inflammatory factors IL-1β, IL-6 and TNF-α in kidneys were examined by quantitative real-time PCR to further validate the sequencing results. As expected, all these factors demonstrated a significant rise in the obstructed kidneys of UUO group, but were notably reduced following icariin treatment (Figure 2D). Moreover, we analyzed inflammatory cell infiltration of renal tissue by immunostaining of F4/80 and found significantly fewer F4/80-positive macrophages in icariin-treated mice than in sham group (Figure 2G).
The heatmap of oxidoreductase-related gene levels revealed that icariin reversed UUO-induced alterations of important oxidoreductase and improved redox balance (Figure 2C). Next, we investigated the levels of MDA, a lipid peroxidation product that is associated with pathological changes in reaction to oxidative stress, and the activity of endogenous SOD in kidney tissue (Figure 2E,F). As a result, we observed significantly increased MDA content and reduced activity of SOD in the obstructed kidneys of UUO mice. Interestingly, treatment with icariin reduced the MDA content and restored the SOD activity, suggesting that the oxidative stress was effectively alleviated by icariin. Taken together, these data demonstrate that icariin can relieve inflammation and oxidative stress, thereby delaying TIF in UUO mice.