Chemopreventive effect of five drugs on renal interstitial fibrosis induced by an aristolochic acid-containing Chinese herb in rats

Role of mineralocorticoid receptor antagonists in kidney diseases

Mineralocorticoid receptor (MR) antagonists, for example, spironolactone and eplerenone, are in clinical use to treat hypertension. Increasing evidence suggests that mineralocorticoid receptor activation causes the pathogenesis and progression of chronic kidney disease. Aldosterone-induced MR activation increases inflammation, fibrosis, and oxidative stress in the kidney. MR antagonists (MRAs) have demonstrated therapeutic actions in chronic kidney disease (CKD), diabetic nephropathy (DN), renal fibrosis, and drug-induced renal injury in preclinical and clinical studies. We have summarized and discussed these studies in this review. The nonsteroidal MRA, esaxerenone, recently received approval for the treatment of hypertension. It has also shown a positive therapeutic effect in phase 3 clinical trials in patients with DN. Other nonsteroidal MRA such as apararenone, finerenone, AZD9977, and LY2623091 are in different clinical trials in patients with hypertension suffering from renal or hepatic fibrotic diseases. Hyperkalemia associated with MRA therapy has frequently led to the discontinuation of the treatment. The new generation nonsteroidal MRAs like esaxerenone are less likely to cause hyperkalemia at therapeutic doses. It appears that the nonsteroidal MRAs can provide optimum therapeutic benefit for patients suffering from kidney diseases.

QiDiTangShen Granules Reduced Diabetic Kidney Injury by Regulating the Phosphorylation Balance of the Tyrosine and Serine Residues of Insulin Receptor Substrate 1

Background

Diabetic nephropathy (DN) is a microvascular complication induced by diabetes mellitus (DM), which can affect life quality and long-term prognosis of patients with DM. Angiotensin-converting-enzyme inhibitors (ACEI)/angiotensin receptor blockers (ARB) are currently recommended for treating DN proteinuria, but patients receiving ACEI/ARB are at risk of elevated serum creatinine or potassium levels. Based on the “yin-yang” theory of traditional Chinese medicine, the present study explored the effect of QiDiTangShen (QDTS) granules on DN and the phosphorylation balance of tyrosine and serine residues of IRS-1.

Methods

In this experiment, db/db mice were used as an animal model for type 2 diabetic nephropathy. The intervention (QDTS granules and valsartan) started when the mice were 12 weeks old. C57BL/6 mice were used as normal control. The urine albumin excretion ratio (UAER) was measured by enzyme-linked immunosorbent assay (ELISA) before and after the intervention. The IRS-1, PI3K, Akt, and MAPK proteins expression and the phosphorylation levels were detected by western blot.

Results

QDTS granules reduced the 24-h urinary albumin excretion rate (UAE) in db/db mice with type 2 DM and attenuated the pathological changes of the kidney. QDTS granules also increased the activation level of the PI3K/Akt signaling pathway and reduced insulin resistance. In addition, QDTS granules inhibited the activation of ERK and p38MAPK and decreased the phosphorylation ratio of Ser307/Tyr896 of IRS-1 in renal tissue.

Conclusions

QDTS granules reduced DM-induced renal injury by improving insulin sensitivity via suppressing MAPK signaling and restoring the phosphorylation balance of tyrosine/serine of IRS-1.

Simultaneous determination of 10 active components in traditional Chinese medicine "YIGONG" capsule by RP-HPLC-DAD

A simple, reliable and accurate method for the simultaneous separation and determination of 10 active components (psoralen, isopsoralen, emodin, oleanolic acid, stachydrine hydrochloride, ammonium glycyrrhizinate, glycyrrhizinate, schizandrol, imperatorin and isoimperatorin) in traditional Chinese medicine "YIGONG" capsule was developed using reverse phase high-performance liquid chromatography (RP-HPLC) coupled with diode array detection. The chromatographic separation was performed on a Eurospher C(18) column (250 mm x 4.6 mm i.d. with 5.0 microm particle size) with a acetonitrile-water gradient containing 0.5% (v/v) aqueous phosphoric acid as mobile phase. Two detection wavelengths (210 and 250 nm) were utilized for the quantitative analysis due to the different UV spectra of these components. Good linear behaviors over the investigated concentration ranges were observed with the values of R(2) higher than 0.999 for all the analytes. The recoveries, measured at three concentration levels, varied from 95.0 to 105.3%. The validated method was successfully applied to the simultaneously determination of these active components in "YIGONG" capsule from different production batches.

Role of peritubular capillary loss and hypoxia in progressive tubulointerstitial fibrosis in a rat model of aristolochic acid nephropathy

BACKGROUND/AIMS

To investigate the effects of peritubular capillary (PTC) loss and hypoxia on the progression of tubulointerstitial fibrosis in a rat model of aristolochic acid nephropathy (AAN).

METHODS

Female Wistar rats received Caulis aristolochiae manshuriensis (CAM) decoction by gavage for 8 weeks, and were sacrificed at 8, 12 and 16 weeks, respectively, after administration. Blood urea nitrogen (BUN), serum creatinine (Scr) and urinary protein were monitored prior to sacrifice. PTC loss and tubulointerstitial hypoxia were assessed by CD34 immunostaining and hypoxia-inducible factor-alpha subunit 1 (HIF-1alpha) expression, respectively. Myofibroblasts were assessed by alpha-smooth muscle actin (alpha-SMA) expression. The expression of angiogenic factor was assessed by vascular endothelial growth factor (VEGF).

RESULTS

AAN rats differed from controls by increased BUN, Scr and 24-hour urinary protein excretion rates. There was a progressive loss of PTCs in the AAN model, which was associated with the decreased expression of VEGF. A significant increase in nuclear localization of HIF-1alpha was seen 16 weeks after treatment with CAM decoction in the context of severe tubulointerstitial damage. Multifocal tubulointerstitial fibrosis was seen in AAN rats at weeks 12 and 16, predominantly in the area of the outer stripe and outer medulla. No significant pathologic changes were found in control rats.

CONCLUSION

Following the reduction of PTCs density and up-regulation of HIF-1alpha, the tubulointerstitial fibrosis area increased. Ischemia and hypoxia are the important causes of severe tubulointerstitial fibrosis in AAN rats.