Shen Shuai II recipe improves renal hypoxia to attenuate renal injury in 5/6 renal ablation/infarction rats and effect evaluation using blood oxygenation level-dependent functional magnetic resonance imaging.

Background: Renal hypoxia plays a key role in the progression of chronic kidney disease (CKD). Shen Shuai II Recipe (SSR) has shown good results in the treatment of CKD as a common herbal formula. This study aimed to explore the effect of SSR on renal hypoxia and injury in CKD rats. Methods: Twenty-five Wistar rats underwent 5/6 renal ablation/infarction (A/I) surgery were randomly divided into three groups: 5/6 (A/I), 5/6 (A/I) + losartan (LOS), and 5/6 (A/I) + SSR groups. Another eight normal rats were used as the Sham group. After 8-week corresponding interventions, blood oxygenation level-dependent functional magnetic resonance imaging (BOLD-fMRI) was performed to evaluate renal oxygenation in all rats, and biochemical indicators were used to measure kidney and liver function, hemoglobin, and proteinuria. The expression of fibrosis and hypoxia-related proteins was analyzed using immunoblotting examination. Results: Renal oxygenation, evaluated by BOLD-fMRI as cortical and medullary T2* values (COT2* and MET2*), was decreased in 5/6 (A/I) rats, but increased after SSR treatment. SSR also downregulated the expression of hypoxia-inducible factor-1α (HIF-1α) in 5/6 (A/I) kidneys. With the improvement of renal hypoxia, renal function and fibrosis were improved in 5/6 (A/I) rats, accompanied by reduced proteinuria. Furthermore, the COT2* and MET2* were significantly positively correlated with the levels of creatinine clearance rate (Ccr) and hemoglobin, but negatively associated with the levels of serum creatinine (SCr), blood urea nitrogen (BUN), serum cystatin C (CysC), serum uric acid (UA), 24-h urinary protein (24-h Upr), and urinary albumin:creatinine ratio (UACR). Conclusion: The degree of renal oxygenation reduction is correlated with the severity of renal injury in CKD. SSR can improve renal hypoxia to attenuate renal injury in 5/6 (A/I) rats of CKD.

Linking renal hypoxia and oxidative stress in chronic kidney disease: Based on clinical subjects and animal models.

This study aims to explore the relationships between renal function, hypoxia, and oxidative stress in chronic kidney disease (CKD). Seventy-six non-dialysis patients with CKD stages 1-5 and eight healthy subjects were included in the clinical research. They were divided into three groups: healthy subjects, CKD stages 1-3, and CKD stages 4-5. In the animal study, 16 rat models of CKD were established through 5/6 renal ablation/infarction (A/I) surgery, and 8 normal rats were split into 3 groups: Sham, CKD, and losartan groups. Blood oxygenation level-dependent magnetic resonance imaging (BOLD-MRI) was used to measure cortical and medullary T2* values (COT2* and MET2*) in all subjects and rats to evaluate renal oxygenation. Biochemical indicators were used to assess renal function and antioxidant capacity. Furthermore, the effects of losartan on renal fibrosis, hypoxia, and oxidative stress were examined using immunoblotting, colorimetric, and fluorometric assays. The results demonstrated significant positive associations between COT2* and MET2* with estimated glomerular filtration rate (eGFR). Patients with CKD stages 4-5 showed significantly lower serum superoxide dismutase (SOD) levels, which also had positive correlations with eGFR, COT2*, and MET2*. Furthermore, losartan treatment resulted in improved renal function and fibrosis, leading to increased levels of COT2*, MET2*, and SOD levels in 5/6 A/I rats. This was accompanied by reduced levels of hypoxia-inducible factor-1 alpha (HIF-1α) and malondialdehyde. Furthermore, losartan restored the expression of nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1), and suppressed the expression of Kelch-like ECH-associated protein 1 (Keap1) in 5/6 A/I kidneys. The study indicates that decline in renal oxygenation and antioxidant capacity is associated with the severity of renal failure in CKD. Losartan can potentially alleviate renal hypoxia and oxidative stress in the treatment of CKD via Keap1-Nrf2/HO-1 pathway.

Shen-Shuai-II-Recipe inhibits tubular inflammation by PPARα-mediated fatty acid oxidation to attenuate fibroblast activation in fibrotic kidneys.

BACKGROUND: Shen Shuai Ⅱ Recipe (SSR) is clinically used to treat chronic kidney diseases (CKDs) with remarkable efficacy and safety. In earlier research, we found the anti-inflammatory, antioxidant, and mitochondrial protective properties of SSR in hypoxic kidney injury model, which is closely related to its renal protection. Further work is needed to understand the underlying molecular mechanisms. PURPOSE: Further investigation of the mechanisms of action of SSR against renal interstitial fibrosis (RIF) building on previous research leads. METHODS: Rats receiving CKD model surgery were given with Fenofibrate or SSR once a day for eight weeks. In vitro, the NRK-52E cells were treated with SSR in the presence or absence of 10 µM Sc75741, 0.5 µM PMA, or 1 µM fenofibrate under 1% O2. The effects of SSR on NF-κB/NLRP3 inflammatory cascade, secretion of pro-inflammatory cytokines, fatty acid oxidation (FAO), and renal tubular injury were determined by immunoblotting, luminex liquid suspension chip assay, transmission electron microscopy, and Oil red O staining. Next, we delivered PPARα-interfering sequences to kidney tissue and NRK-52E cells by adeno-associated virus (AAV) injection and siRNA transfection methods. Finally, we evaluated the effect of renal tubular cells on fibroblast activation by co-culture method. RESULTS: SSR attenuated the release of IL-18, VEGF, and MCP1 cytokines, inhibited the activation of NF-κB/NLRP3 cascade, increased the PPARα, CPT-1α, CPT-2, ACADL, and MCAD protein expression, and improved the lipid accumulation. Further studies have demonstrated that one of the ways in which SSR suppresses the inflammatory response to protect renal tubular cells is through the restoration of PPARα-mediated FAO. In addition, by means of co-culture ways, the results demonstrated that SSR attenuated secretion of inflammatory mediators in NRK-52E cells by PPARα/NF-κB/NLRP3 pathway, thereby inhibiting renal fibroblast activation. CONCLUSION: SSR inhibits RIF by suppressing inflammatory response of hypoxia-exposed RTECs through PPARα-mediated FAO.

Correlation of Renal Oxygenation with Renal Function in Chronic Kidney Disease: A Preliminary Prospective Study.

INTRODUCTION: Chronic hypoxia is prevalent in chronic kidney disease (CKD), and blood oxygenation level-dependent magnetic resonance imaging (BOLD-MRI) provides noninvasive evaluation of renal oxygenation. This study aimed to explore the correlation of renal oxygenation evaluated by BOLD-MRI with renal function. METHODS: 97 non-dialysis patients with CKD stages 1-5 and healthy volunteers (HVs) were recruited in the study, all participants without diabetes. Based on their estimated glomerular filtration rate (eGFR), the patients were divided into two groups: CKD stages 1-3 (CKD 1-3) and CKD stages 4-5 (CKD 4-5). We measured cortical and medullary T2* (COT2* and MET2*) values in all participants by BOLD-MRI. Physiological indices were also recorded and compared among three groups. Correlation of T2* values with clinical characteristics was determined. RESULTS: The COT2* values were significantly higher than MET2* values in all participants. The COT2* and MET2* values of three groups were ranked as HV > CKD 1-3> CKD 4-5 (p < 0.0001). There were positive correlations between the COT2* values, MET2* values and eGFR, hemoglobin (r > 0.4, p < 0.01). The 24-h urinary protein (24-h Upr) showed weak correlation with the COT2* value (rs = -0.2301, p = 0.0265) and no correlation with the MET2* value (p > 0.05). Urinary microprotein, including urinary alpha1-microglobulin, urinary beta2-microglobulin (ß2-MG), and urinary retinol-binding protein (RBP), showed strong correlation with COT2* and MET2* values. According to the analysis of receiver operating characteristic curve, the optimal cut-points between HV and CKD 1-3 were "<61.17 ms" (sensitivity: 91.23%, specificity: 100%) for COT2* values and "<35.00 ms" (sensitivity: 77.19%, specificity: 100%) for MET2* values, whereas COT2* values ("<47.34 ms"; sensitivity: 90.00%, specificity: 92.98%) and MET2* values ("<25.09 ms"; sensitivity: 97.50%, specificity: 80.70%) between CKD 1-3 and CKD 4-5. CONCLUSION: The decline of renal oxygenation reflected on T2* values, especially in cortex, may be an effective diagnostic marker for early detection of CKD.

Evaluation of Renal Oxygenation and Hemodynamics in Patients with Chronic Kidney Disease by Blood Oxygenation Level-dependent Magnetic Resonance Imaging and Intrarenal Doppler Ultrasonography.

INTRODUCTION: The basic pathophysiologic derangement of chronic kidney disease (CKD) begins with the loss of nephrons, leading to renal hemodynamic changes, eventually causing a reduced nephron count and renal hypoxia. The purpose of this study was to observe the renal oxygenation and renal hemodynamics of patients with CKD using blood oxygenation level-dependent (BOLD) magnetic resonance imaging (MRI) and intrarenal Doppler ultrasonography (IDU). METHODS: The study enrolled 39 patients with stage 1-4 CKD and 19 healthy volunteers (HVs). Based on their estimated glomerular filtration rate (eGFR), CKD patients were divided into 2 subgroups: a mild renal impairment (MI) group and a moderate to severe renal impairment (MSI) group. We monitored the participants' mean cortical T2* (COT2*) and mean medullary T2* (MET2*) values on BOLD-MRI, and measured the peak systolic velocities (PSVs), end-diastolic velocities (EDVs), renal resistive index (RI), and kidney length by IDU. We also recorded clinical indicators such as age, sex, body mass index (BMI), 24-h urinary protein (24-h Upr), serum creatinine (sCr), blood urea nitrogen (BUN), and eGFR. BOLD-MRI, IDU measurements, and the clinical indicators were compared in CKD patients and HVs by the analysis of variance and Kruskal-Wallis H test. Spearman's correlation was used to assess the relationship between data from BOLD-MRI and IDU and clinical indicators. RESULTS: The COT2* values were significantly higher than the MET2* values in the HV, MI, and MSI groups. COT2*, MET2*, EDV, PSV, and kidney length gradually decreased in the HV, MI, and MSI groups (all p < 0.05), whereas RI and 24-h Upr gradually increased (both p < 0.05). Spearman correlation analysis showed that COT2* and MET2* were significantly positively correlated with eGFR, PSV, EDV, and kidney length but were significantly negatively correlated with sCr, BUN, and 24-h Upr (all p < 0.05). There was no correlation observed between the COT2* and MET2* and the RI and BMI values. CONCLUSIONS: Renal oxygenation and blood flow velocities were found declined as the CKD stage progressed. The BOLD-MRI and IDU techniques may have clinical value by measuring intrarenal oxygenation and renal blood perfusion to judge the severity of renal damage in patients with CKD.