Renal fibrosis is the major cause of chronic kidney disease, and the Rho/Rho-associated coiled-coil kinase (ROCK) signaling cascade is involved in the renal fibrotic processes. Several studies have reported that ROCK inhibitors attenuate renal fibrosis. However, the mechanism of this process remains to be fully elucidated. The present study assessed the inhibitory effect of fasudil, a ROCK inhibitor using immunohistochemistry, reverse transcription-quantitative polymerase chain reaction and western blot analyses, in vivo and in vitro, to elucidate the mechanisms underlying renal interstitial fibrosis. In mice induced with unilateral ureteral obstruction (UUO), collagen accumulation, the expression of fibrosis‑associated genes and the content of hydroxyproline in the kidney increased 3, 7, and 14 days following UUO. Fasudil attenuated the histological changes, and the production of collagen and extracellular matrix in the UUO kidney. The expression of α‑smooth muscle actin (α‑SMA) and the transforming growth factor‑β (TGFβ)‑Smad signaling pathway, and macrophage infiltration were suppressed by fasudil in the kidneys of the UUO mice. The present study also evaluated the role of intrinsic renal cells and infiltrated macrophages using NRK‑52E, NRK‑49F and RAW264.7 cells. The mRNA and protein expression levels of collagen I and α‑SMA increased in the NRK‑52E and NRK‑49F cells stimulated by TGF‑β1. Hydroxyfasudil, a bioactive metabolite of fasudil, attenuated the increase in the mRNA and protein expression levles of α‑SMA in the two cell types. However, the reduction in the mRNA expression of collagen I was observed in the NRK‑49F cells only. Hydroxyfasudil decreased the mRNA expression of monocyte chemoattractant protein‑1 (MCP‑1) induced by TGF‑β1 in the NRK‑52E cells, but not in the NRK‑49F cells. In the RAW264.7 cells, the mRNA expression levels of MCP‑1, interleukin (IL)‑1β, IL‑6 and tumor necrosis factor α were increased significantly following lipopolysaccharide stimulation, and were not suppressed by hydroxyfasudil. These data suggested that the inhibition of ROCK activity by fasudil suppressed the transformation of renal intrinsic cells into the myofibroblast cells, and attenuated the infiltration of macrophages, without inhibiting the expression or the activation of cytokine/chemokines, in the progression of renal interstitial fibrosis.

Loss of peritubular capillaries is a notable feature of progressive renal interstitial fibrosis. Astaxanthin (ASX) is a natural carotenoid with various biological activities. The present study aimed to evaluate the effect of ASX on unilateral ureteral obstruction (UUO)‑induced renal fibrosis in mice. For that purpose, mice were randomly divided into five treatment groups: Sham, ASX 100 mg/kg, UUO, UUO + ASX 50 mg/kg and UUO + ASX 100 mg/kg. ASX was administered to the mice for 7 or 14 days following UUO. The results demonstrated that UUO‑induced histopathological changes in the kidney tissue were prevented by ASX. Renal function was improved by ASX treatment, as evidenced by decreased blood urea nitrogen and serum creatinine levels. Furthermore, the extent of renal fibrosis and collagen deposition induced by UUO was suppressed by ASX. The levels of collagen I, fibronectin and α‑smooth muscle actin were increased by UUO in mice or by transforming growth factor (TGF)‑β1 treatment in NRK‑52E cells, and were reduced by ASX administration. In addition, ASX inhibited the UUO‑induced decrease in peritubular capillary density by upregulating vascular endothelial growth factor and downregulating thrombospondin 1 levels. Inactivation of the TGF‑β1/Smad signaling pathway was involved in the anti‑fibrotic mechanism of ASX in UUO mice and TGF‑β1‑treated NRK‑52E cells. In conclusion, ASX attenuated renal interstitial fibrosis and peritubular capillary rarefaction via inactivation of the TGF‑β1/Smad signaling pathway.

The effect of ulinastatin (UTI) on renal tubular epithelial apoptosis and interstitial fibrosis in rats with unilateral ureteral obstruction (UUO) was investigated. A total of 18 male Wistar rats were randomly divided into the following 3 groups: The Sham group (n=6), the UUO group (n=6), and the UTI group (n=6). In the UUO and UTI groups, the left ureter was ligated to establish a UUO model. Starting from day 1 after surgery, an intervention treatment was performed using normal saline (1 ml/kg/d) and UTI (40,000 unit/kg/d). On day 7 after surgery, 6 rats from each group were sacrificed. In the Sham group, the left ureter was only freed, not ligated; after 7 days of abdominal closure, all of the rats were sacrificed. Blood samples were collected prior to sacrificing the animals to measure the blood urea nitrogen (BUN) and serum creatinine (Scr). The incidence of renal interstitial lesions on the obstruction side was observed by hematoxylin and eosin, and Masson staining. Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining, and immunohistochemical detection of apoptosis regulator Bax (Bax), apoptosis regulator Bcl‑2 (Bcl‑2) and caspase‑3 were performed to observe the presence of renal tubular epithelial cell apoptosis. The UTI did not have a significant influence on the mouse BUN and Scr levels in any of the groups (P>0.05). Compared with that in the Sham group, renal tissue injury in the UUO group was significantly aggravated with renal tubular dilation, epithelial cell atrophy, renal interstitial inflammatory cell infiltration and fibrous tissue hyperplasia (P<0.01). Furthermore, the renal tubular epithelial TUNEL+ cell number and Bax and caspase‑3 levels were increased, and the expression of Bcl‑2 was decreased (P<0.01). Following the UTI treatment, the renal interstitial injury at the obstruction side was significantly attenuated (P<0.05), the renal tubular epithelial TUNEL+ cell number, and Bax and caspase‑3 levels significantly decreased, and the expression of Bcl‑2 was restored (P<0.05). UTI inhibited renal tubular epithelial apoptosis and interstitial fibrosis in UUO rats.

Renal fibrosis, considered to be a common consequence of progressive renal disease, involves glomerulosclerosis and/or tubulointerstitial fibrosis. Currently, research is focused on investigating potential mechanisms to prevent or reverse the damage caused by fibrosis. Under the influence of cytokines, chemokines and other signaling molecules, the cellular interactions that regulate the development of interstitial fibrosis are complex. Epithelial‑mesenchymal transition (EMT) has emerged as an important pathway leading to the generation of matrix‑producing fibroblasts and myofibroblasts in diseased kidneys. The proteomics study compared the protein profiles between the time points of podocyte EMT and tubular cell EMT in a partial unilateral ureteral obstruction (PUUO) model in rats. Proteins isolated from the PUUO group and corresponding sham rat kidney tissues were subjected to 2‑D gel electrophoresis and were then identified by mass spectrometry. In total, 43 proteins with differential expression were identified, which were reported to be involved in the regulation of the cytoskeleton and actin, glucose metabolism, cell apoptosis, mitochondrial energy metabolism, oxidative stress and endoplasmic reticulum stress. Electron transfer flavoprotein, β polypeptide was detected by immunoblot analysis and its mRNA levels were determined in renal tissues. The results demonstrate protein alterations that reflect the pathology of the obstructed kidneys, and thus may aid in understanding the pathogenesis of obstructive nephropathy.

Mesenchymal stem cell‑conditioned medium (MSC‑CM) contains various cytokines (osteopontin and macrophage colony stimulating factor 1) secreted by MSCs and may modulate the immune response in tubulointerstitial fibrosis. The aim of the present study was to investigate whether MSC‑CM treatment may affect B cell‑dependent immune responses, which have previously been reported to facilitate the renal fibrotic processes following unilateral ureteral obstruction (UUO). In the present study, histological analysis, flow cytometry, western blotting and reverse transcription‑quantitative polymerase chain reaction were performed. MSC‑CM treatment was observed to impede renal infiltration of B lymphocytes and the expression of CC chemokine ligand‑2. Additionally, UUO suppressed the subsequent recruitment of monocytes/macrophages to the kidney, limited local inflammation and attenuated renal fibrosis. The findings of the present study identified a potential mechanism of MSC‑CM in ameliorating the UUO‑kidney.

Renal interstitial fibrosis (RIF) is the main process that leads to renal failure. It is necessary to investigate the mechanism of RIF and identify appropriate methods of regulating it. Furthermore, unilateral ureteral obstruction is a frequently used model for the study of RIF. The morphological damage associated with kidney and lung dysfunction was detected using histopathological experiments. Subsequently, high expression of reactive oxygen species (ROS) modulator 1 (ROMO1) and ROS was measured in blood serum. In addition, epithelial‑mesenchymal transition marker, transforming growth factor β (TGF‑β) and mothers against decapentaplegic homolog 2/3 expression was evaluated using the reverse transcription‑quantitative polymerase chain reaction and western blotting. All serious symptoms were relieved to a certain extent following oxidation inhibitor intervention using three common antioxidants. HK‑2 cells were treated with H2O2 to cause oxidative stress, and ROMO1 and fibrosis marker expression increased; however, activation was suppressed byROMO1 knockout. The present study provides evidence that the expression of ROMO1 induces ROS production and activates the TGF‑β signaling pathway. It may be concluded that ROMO1 helps to provide a molecular basis for improved clinical intervention and prognosis of patients.

The aim of the present study was to investigate the protective effects of N‑acetylcysteine (NAC) on contrast‑induced acute kidney injury in rats with unilateral hyronephrosis. Eighty‑two male Sprague Dawley rats were randomized to undergo sham operation (n=14) or unilateral ureteral obstruction (UUO) (n=68). After 3 weeks, the UUO animals were randomized to three groups: NAC gastric perfusion, UUO+iohexol+NAC (n=24); normal saline perfusion, UUO+iohexol (n=24); and controls, UUO (n=20). After 3 days, UUO+iohexol+NAC and UUO+iohexol rats were injected with iohexol. One day after contrast, half of the rats were sacrificed to assess the pathological changes to the kidneys, serum creatinine, serum neutrophil gelatinase‑associated lipocalin (NGAL), renal cell apoptosis rate and expression of apoptosis regulators Bcl‑2/Bax. The remaining rats underwent obstruction relief and were analyzed 3 weeks later. Compared with the controls, serum NGAL levels were high in UUO+iohexol rats 1 day following injection and 3 weeks after obstruction relief, but UUO+iohexol+NAC rats exhibited lower serum NGAL levels compared with UUO+iohexol rats (all P<0.05). Following modeling, UUO+iohexol rats exhibited a significantly higher apoptosis rate of renal tubular cells, higher expression of Bax mRNA, and lower ratio of Bcl‑2/Bax (all P<0.05). Three weeks after obstruction relief, UUO+iohexol+NAC rats exhibited a lower apoptosis rate, lower Bax mRNA expression, higher expression of Bcl‑2 mRNA and higher ratio of Bcl‑2/Bax (all P<0.05) compared with day 1 following drug administration. The prophylactic use of NAC reduced the apoptotic rate of renal tubular cells following contrast exposition, which was accompanied by changes in the expression of Bcl‑2/Bax mRNA.

The peroxisome proliferator‑activated receptor γ (PPARγ) agonist pioglitazone has been widely used in previous studies to ameliorate diabetes mellitus and regulate inflammation. However, the present study aimed to investigate the effect of pioglitazone on macrophages and determine its impact on renal fibrosis in vivo. Firstly, bone marrow‑derived macrophages (BMDM) were used to detect the effects of pioglitazone on macrophages in vitro. It was demonstrated that pioglitazone promoted M2 macrophage activation and induced vascular endothelial growth factor receptor 3 (VEGFR3) upregulation in a PPARγ‑dependent manner. Furthermore, pioglitazone increased macrophage proliferation and macrophage VEGFR3 expression in a murine unilateral ureteral obstruction (UUO) model; however, it had no therapeutic effect on renal fibrosis in vivo. Therefore, the results in the present study implied that presence of M2 macrophages may inhibit pioglitazone's ability to attenuate UUO‑induced renal fibrosis. In addition, the results demonstrated that macrophage‑associated VEGFR3 could be induced by pioglitazone, although it is still unclear what role VEGFR3+ M2 macrophages have in renal fibrosis.

Sedum sarmentosum Bunge (SSBE) is a perennial plant widely distributed in Asian countries, and its extract is traditionally used for the treatment of certain inflammatory diseases. Our previous studies demonstrated that SSBE has marked renal anti‑fibrotic effects. However, the underlying molecular mechanisms remain to be fully elucidated. The present study identified that SSBE exerts its inhibitory effect on the myofibroblast phenotype and renal fibrosis via the hedgehog signaling pathway in vivo and in vitro. In rats with unilateral ureteral obstruction (UUO), SSBE administration reduced kidney injury and alleviated interstitial fibrosis by decreasing the levels of transforming growth factor (TGF)‑β1 and its receptor, and inhibiting excessive accumulation of extracellular matrix (ECM) components, including type I and III collagens. In addition, SSBE suppressed the expression of proliferating cell nuclear antigen, and this anti‑proliferative activity was associated with downregulation of hedgehog signaling activity in SSBE‑treated UUO kidneys. In cultured renal tubular epithelial cells (RTECs), recombinant TGF‑β1 activated hedgehog signaling, and resulted in induction of the myofibroblast phenotype. SSBE treatment inhibited the activation of hedgehog signaling and partially reversed the fibrotic phenotype in TGF‑β1‑treated RTECs. Similarly, aristolochic acid‑mediated upregulated activity of hedgehog signaling was reduced by SSBE treatment, and thereby led to the abolishment of excessive ECM accumulation. Therefore, these findings suggested that SSBE attenuates the myofibroblast phenotype and renal fibrosis via suppressing the hedgehog signaling pathway, and may facilitate the development of treatments for kidney fibrosis.

Previous studies have demonstrated the potential antifibrotic effects of baicalin in vitro, via examination of 21 compounds isolated from plants. However, its biological activity and underlying mechanisms of action in vivo remain to be elucidated. The present study aimed to evaluate the effect of baicalin on renal fibrosis in vivo, and the potential signaling pathways involved. A unilateral ureteral obstruction (UUO)‑induced renal fibrosis model was established using Sprague‑Dawley rats. Baicalin was administrated intraperitoneally every 2 days for 10 days. The degree of renal damage and fibrosis was investigated by histological assessment, and detection of fibronectin and collagen I mRNA expression levels. Epithelial‑mesenchymal transition (EMT) markers, transforming growth factor-β1 (TGF-β1) levels and downstream phosphorylation of mothers against decapentaplegic 2/3 (Smad2/3) were examined in vivo and in an NRK‑52E rat renal tubular cell line in vitro. Baicalin was demonstrated to markedly ameliorate renal fibrosis and suppress EMT, as evidenced by reduced interstitial collagen accumulation, decreased fibronectin and collagen I mRNA expression levels, upregulation of N‑ and E‑cadherin expression levels, and downregulation of α‑smooth muscle actin and vimentin expression. Furthermore, baicalin decreased TGF‑β1 expression levels in serum and kidney tissue following UUO, and suppressed Smad2/3 phosphorylation in rat kidney tissue. In vitro studies identified that baicalin may inhibit the phosphorylation of Smad2/3 under the same TGF‑β1 concentration. In conclusion, baicalin may protect against renal fibrosis, potentially via inhibition of TGF‑β1 production and its downstream signal transduction.

Renal interstitial fibrosis is one of the common causes, and a major pathological basis for the development of various types of chronic progressive renal to end‑stage renal diseases. Therefore, it is important to clarify the underlying mechanisms of disease progression in order to develop effective strategies for the treatment and prevention of these pathologies. The aim of the present study was to investigate the association between microRNA (miR)‑212 expression and the development of renal interstitial fibrosis, as well as analyzing the role of miR‑212 in the disease. The expression of miR‑212 was significantly increased in the peripheral blood of patients with renal interstitial fibrosis and in the kidney tissues of unilateral ureteral obstruction (UUO) mice. Angiotensin (Ang) II, TGF‑β1 and hypoxia were found to increase the expression of miR‑212 and α smooth muscle actin (α‑SMA) in NRK49F cells. Ang II stimulation induced the expression of miR‑212 and α‑SMA in NRK49F cells, while transfection of miR‑212 mimics further upregulated the expression of α‑SMA. miR‑212 was also revealed to target hypoxia‑inducible factor 1α inhibitor (HIF1AN) and to upregulate the expression of hypoxia‑inducible factor 1α, α‑SMA, connective tissue growth factor, collagen α‑1(I) chain and collagen α‑1(III) chain, whereas HIF1AN overexpression reversed the regulatory effects of miR‑212. In UUO mice, miR‑212 overexpression promoted the progression of renal interstitial fibrosis, whereas inhibiting miR‑212 resulted in the opposite effect. These results indicated that high expression of miR‑212 was closely associated with the occurrence of renal interstitial fibrosis, and that miR‑212 may promote its development by targeting HIF1AN.

The implications of epithelial‑mesenchymal transdifferentiation (EMT) have extended beyond the confines of renal fibrosis to renal tubulointerstitial fibrosis. It has been proposed that EMT may be one of the mechanisms involved in the pathogenesis of renal fibrosis. However, the underlying mechanisms remain unknown. Transforming growth factor (TGF)‑β1 is considered to be an important cytokine which regulates the transdifferentiation of tubular epithelial cells into myofibroblasts in renal tubulointerstitial fibrosis. In the present study, normal rat kidney tubular epithelial cells (NRK‑52E) were treated for 48 h with TGF‑β1 (5 ng/ml) and different concentrations of artesunate (ART; 0.01, 0.1 and 1 µg/ml). Western blotting, reverse transcription‑semi quantitative polymerase chain reaction analysis and immunofluorescence staining were used to evaluate the expression of bone morphogenetic protein (BMP)‑7, uterine sensitization‑associated gene (USAG)‑1, E‑cadherin, α‑smooth muscle actin (α‑SMA) and extracellular matrix collagen type I (Col I) mRNA. ART was able to attenuate renal injury in a unilateral ureteral obstruction model. However, its anti‑fibrotic effect remains to be elucidated. In the present study, it was observed that ART was able to ameliorate the TGF‑β1‑induced alterations in cellular morphology. In addition, ART inhibited the TGF‑β1‑induced USAG‑1 increase and the decrease in BMP‑7. Treatment with ART markedly attenuated the TGF‑β1‑induced upregulation of α‑SMA and downregulation of E‑cadherin. Additionally, ART was able to significantly attenuate the deposition of interstitial collagens, including Col I. The results of the present study further verified the therapeutic efficacy of ART in TGF‑β1‑induced renal interstitial fibrosis. These findings indicated that ART may hold the potential to prevent chronic kidney diseases via the suppression of USAG‑1 expression or by increasing BMP‑7 expression.

Our previous study demonstrated that febuxostat, a xanthine oxidase inhibitor, can alleviate kidney dysfunction and ameliorate renal tubulointerstitial fibrosis in a rat unilateral ureteral obstruction (UUO) model; however, the underlying mechanisms remain unknown. Increasing evidence has revealed that epithelial‑mesenchymal transition (EMT) is one of the key mechanisms mediating the progression of renal tubulointerstitial fibrosis in chronic kidney disease (CKD). Uterine sensitization‑associated gene‑1 (USAG‑1), a kidney‑specific bone morphogenetic protein antagonist, is involved in the development of numerous types of CKDs. The present study aimed to investigate the role of febuxostat in the process of EMT in Madin‑Darby canine kidney (MDCK) cells in vitro. Western blotting, reverse transcription‑semiquantitative polymerase chain reaction analysis and immunofluorescence staining were used to evaluate the expression levels of bone morphogenetic protein 7, USAG‑1, α‑smooth muscle actin (α‑SMA) and E‑cadherin, respectively. The results demonstrated that the expression of USAG‑1 and α‑SMA increased, and that of E‑cadherin decreased significantly in MDCK cells following treatment with transforming growth factor‑β1 (TGF‑β1). The application of small interfering RNA‑USAG‑1 potently inhibited TGF‑β1‑induced EMT. Subsequently, the effects of febuxostat on TGF‑β1‑induced EMT was investigated. The results demonstrated that febuxostat downregulated the expression of USAG‑1, and reversed TGF‑β1‑induced EMT in MDCK cells. Furthermore, pretreatment with febuxostat significantly restored the decreased expression levels of phosphorylated Smad1/5/8 induced by TGF‑β1 in MDCK cells. The results of the present study suggested that USAG‑1 may be involved in the EMT process of MDCK cells induced by TGF‑β1, and febuxostat inhibited EMT by activating the Smad1/5/8 signaling pathway via downregulating the expression of USAG‑1 in MDCK cells.

The aim of the present study was to investigate whether urinary kidney injury molecule‑1 (KIM‑1) presents a suitable early diagnostic biomarker of obstructive nephropathy‑induced acute kidney injury (AKI), and to develop a rapid detection method for urinary KIM‑1. Obstructive AKI was induced in an experimental rat model by a unilateral ureteral obstruction (UUO) operation. Macro‑ and micromorphological kidney alterations were determined by visual observation and hematoxylin and eosin (HE) staining, respectively. Kidney functions were evaluated by detecting urea nitrogen and creatinine levels in rat urine and blood. Urinary KIM‑1 levels were measured using an enzyme‑linked immunosorbent assay, and the protein expression levels of KIM‑1, α‑smooth muscle actin (α‑SMA) and vimentin in kidney tissues were detected using immunohistochemical assays. In order to measure KIM‑1 levels, colloidal gold immunochromatographic strips were developed based on the colloidal gold immunochromatographic assay. The results indicated that KIM‑1 levels were significantly higher in the UUO group when compared with the Sham group. KIM‑1 levels in the urine and kidney tissues exhibited a time‑dependent increase, together with increasing obstructive AKI in the UUO group. In addition, KIM‑1 levels were demonstrated to be a more sensitive biomarker of early obstructive AKI, when compared with α‑SMA and vimentin. A colloidal gold‑based immunochromatographic strip was developed, whereby the detection of urinary KIM‑1 could be completed within 5‑10 min. In conclusion, results of the present study demonstrated that urinary KIM‑1 may be a valuable biomarker for the early diagnosis of obstructive AKI, and the use of a colloidal gold immunochromatographic strip may be a promising method for the rapid detection of urinary KIM‑1.

Dioscin (DIS) is a natural compound derived from Chinese herbal medicine. In recent years, multiple studies have reported that DIS has immunoregulation, anti‑fibrosis, anti‑inflammation, anti‑viral and anti‑tumor effects. However, the mechanism by which DIS ameliorates renal fibrosis and inflammation remains to be elucidated. The aim of the present study was to investigate the role of DIS in renal fibrosis and inflammation and to explore its underlying mechanism. It used network pharmacology to predict the targets of DIS for the treatment of renal interstitial fibrosis. The present study was performed using unilateral ureteral obstruction mice and HK‑2 cells in vivo and in vitro. The mice were treated with different doses of DIS. Kidney tissues were collected for histopathology staining, western blotting, immunohistochemistry staining and reverse transcription‑quantitative (RT‑q) PCR. TGF‑β1 (2 ng/ml) was used to induce renal fibrosis in the cells. Then, cells were respectively treated with DIS (3.125, 6.25, 12.5 µM) and Bay11‑7082 (an inhibitor of NF‑κB p65 nuclear transcription, 1 µM) for another 24 h. The expressions of inflammatory factors and NF‑κB pathway proteins were detected by immunofluorescence, ELISA, western blotting and RT‑qPCR. DIS alleviated renal injury in the UUO mice. Mechanistically, DIS not only decreased the expressions of inflammatory factors including IL‑1β, NOD‑like receptor thermal protein domain associated protein 3, monocyte chemotactic protein 1, IL‑6, TNF‑α and IL‑18 but also reduced the level of phosphorylation of NF‑κB p65 in vivo and in vitro, which was similar to the impact of Bay11‑7082. DIS ameliorated renal fibrosis by inhibiting the NF‑κB signaling pathway‑mediated inflammatory response, which may be a therapeutic pathway for delaying chronic kidney disease.

A number of studies have shown that aldosterone serves an important role in promoting renal interstitial fibrosis, although the specific mechanism remains to be elucidated. A previous study revealed that the fibrotic effect of aldosterone was associated with the expression of allograft inflammatory factor 1 (AIF‑1) in RAW264.7 macrophage cells, in a time‑ and concentration‑dependent manner. However, the exact mechanism through which aldosterone promotes renal interstitial fibrosis remains unknown. In the present study, the effects of aldosterone on renal inflammatory cell infiltration, collagen deposition and the expression levels of AIF‑1, phosphatidylinositol 3‑kinase (PI3K), AKT serine/threonine kinase (AKT), mammalian target of rapamycin (mTOR), the oxidative stress factor NADPH oxidase 2 (NOX2) and nuclear transcription factor erythroid‑related factor 2 (Nrf2) were assessed in normal rats, rats treated with aldosterone, rats treated with aldosterone and spironolactone and those treated with spironolactone only (used as the control). The effect of aldosterone on these factors was also investigated in the renal interstitium of unilateral ureteral obstruction (UUO) rats. Additionally, the AIF‑1 gene was overexpressed and knocked down in macrophage RAW264.7 cells, and the effects of aldosterone on PI3K, AKT, mTOR, NOX2 and Nrf2 were subsequently investigated. The results showed that aldosterone promoted inflammatory cell infiltration, collagen deposition and the expression of AIF‑1, PI3K, AKT, mTOR and NOX2, but inhibited the expression of Nrf2. In the UUO rats, aldosterone also promoted renal interstitial inflammatory cell infiltration, collagen deposition and the expression of AIF‑1, NOX2, PI3K, AKT and mTOR, whereas the expression of Nrf2 was downregulated by aldosterone compared with that in the UUO‑only group; the influence of aldosterone was counteracted by spironolactone in the normal and UUO rats. In vitro, aldosterone upregulated the expression levels of AKT, mTOR, NOX2 and Nrf2 in RAW264.7 cells compared with those in untreated cells. Suppressing the expression of AIF‑1 inhibited the effects of aldosterone, whereas the overexpression of AIF‑1 enhanced these effects in RAW264.7 cells. These findings indicated that aldosterone promoted renal interstitial fibrosis by upregulating the expression of AIF‑1 and that the specific mechanism may involve AKT/mTOR and oxidative stress signaling.