Effect of ipsilateral ureteric obstruction on contralateral kidney and role of renin angiotensin system blockade on renal recovery in experimentally induced unilateral ureteric obstruction

Investigation of reno-protective efficacy of thymoquinone in a unilateral hydronephrosis model

We aimed to evaluate the effects of the antioxidant thymoquinone on treated and untreated kidneys on histological and oxidative parameters as well as Kidney Injury Molecule (KIM-1) levels in an experimental unilateral ureteropelvic junction obstruction (UPJO) with resultant hydronephrosis (HN) model. In adherence to the Animal research: reporting of in vivo exepriments guidelines, 34 male Wistar rats were randomly divided into four groups which were named accordingly: "CO" (corn oil), "TQ" (thymoquinone and corn oil), "HNCO" (UPJO-HN and corn oil), "HNTQ" (UPJO-HN, thymoquinone and corn oil). Histologically, pelvic epithelial damage, glomerular shrinkage and sclerosis, tubular damage, interstitial edema-inflammation-fibrosis (IEIF), and vascular congestion were assessed. Biochemically, malondialdehyde (MDA), superoxide dismutase (SOD), glutathione reductase (GR) and KIM-1 levels were assessed. Macroscopic HN developed in all obstructed kidneys. Ipsilateral obstructed kidneys deteriorated in all histological parameters. Thymoquinone attenuated glomerular shrinkage and sclerosis alterations but increased vascular congestion. Contralateral non-obstructed kidneys also showed histological deterioration. Thymoquinone had beneficial effects in terms of IEIF presence in contralateral kidneys but it increased vascular congestion. MDA and SOD results were inconclusive. UPJO caused decreased GR levels in the ipsilateral kidneys but not in the contralateral ones. This effect was not ameliorated by thymoquinone treatment. KIM-1 levels were increased in ipsilateral obstructed kidneys with a lower level in HNTQ group than in HNCO. KIM-1 level of the ipsilateral HNTQ group was higher than in both non-obstructed ipsilateral kidney groups. The effect of thymoquinone in ameliorating bilaterally observed histological alterations was limited and controversial. Oxidative damage detected by GR measurements was not prevented by thymoquinone. Thymoquinone partially decreased the damage as evidenced by reduced KIM-1 levels in thymoquinone-treated obstructed kidneys.

The Rho-kinase inhibitor Y27632 promotes ureteral relaxation in an in vivo rat model for partial ureteral obstruction

PURPOSE

Aim of this study was to evaluate the effect of intravenous Y27632 (a ROK inhibitor) on intra-ureteral pressures and on blood pressure in an in vivo rat model for unilateral partial ureteral obstruction (PUO).

METHODS

15 Male Sprague Dawley rats were used. Under isofluran anesthesia, saline was continuously infused via polyethylene (PE)-10 catheters inserted in the ureters beneath the kidney pelvis. Left psoas muscle was sutured around the distal left ureter to create a partial obstruction. Carotid artery and femoral vein were cannulated with PE catheters for registration of mean arterial blood pressure (MAP) and for administration of drugs. Left and right ureter pressures and MAP were simultaneously recorded. Y27632 (0.03 and 0.1 mg/kg each n = 6-7) was given intravenously. T-test was used for comparisons.

RESULTS

Spontaneous peristaltic pressure waves were recorded at baseline for both ureters. After the obstruction, Y27632 reduced maximum pressure (MaxP) by 10.5 ± 1.9% (0.03 mg/kg; p = 0.004) and 29.1 ± 4.8% (0.1 mg/kg; p < 0.001), minimum pressure (MinP) by 5.2 ± 2.3% (0.03 mg/kg; p = 0.02) and 12.2 ± 3.4% (0.1 mg/kg; p = 0.009), the area under the curve (AUC) by 7.8 ± 2.4% (0.03 mg/kg; p = 0.008) and 16.5 ± 3.7% (0.1 mg/kg;p = 0.007), the waves amplitude by 23.4 ± 11.3% (0.03 mg/kg; p = 0.098) and 38.7 ± 7.5% (0.1 mg/kg; p < 0.001), with no effect on contraction frequency. During simultaneous recordings from the normal ureter at the investigated doses, Y27632 reduced MaxP, MinP, AUC and waves amplitude by 1-7%. The MAP was reduced by 12.5 ± 5.3% (0.03 mg/kg; p = 0.07) and 15.8 ± 1.8% (0.1 mg/kg; p < 0.001).

CONCLUSIONS

Y27632 decreased intra-ureteral pressures of a partially obstructed ureter with limited effect on blood pressure in an animal model of unilateral PUO.

Podocyte Injury Through Interaction Between Tlr8 and Its Endogenous Ligand miR-21 in Obstructed and Its Collateral Kidney

While chronic kidney disease is prevalent in adults, obstructive nephropathy (ON) has been reported in both young and old patients. In ON, tubulointerstitial lesions (TILs) have been widely investigated, but glomerular lesions (GLs) have been largely neglected. Here, we show a novel mechanism underlying GL development in ON in young and old mice. TILs develop earlier than GLs owing to infiltration of inflammatory cells in the tubulointerstitium, but GLs develop following the activation of Toll-like receptor 8 (Tlr8) even though the absence of inflammatory cells infiltrating the glomerulus. TLR8 and interleukin 1 beta (IL1β) proteins colocalize with reducing podocyte function markers (PFMs), indicating the activation of TLR8 signaling in injured podocytes. Furthermore, glomerular and serum levels of miR-21, an endogenous ligand for Tlr8, were higher in the ON mouse model than in the sham control. The glomerular expression of Tlr8 positively correlates with miR-21 and the downstream cytokines Il1b and Il6 and negatively correlated with PFMs (Nphs1 and Synpo). We also show the colocalization of TLR8 and IL1β proteins with reducing PFMs in both obstructed and collateral kidney of young and old mice. Furthermore, in vitro study results revealed higher expression of Tlr8 and its downstream cytokines in glomeruli from obstructed kidneys following treatment with miR-21 mimic than in the control. In conclusion, the overexpression of Tlr8 may serve as a plausible mechanism underlying GL development in ON through podocyte injury.

Olmesartan medoxomil reverses glomerulosclerosis in renal tissue induced by myocardial infarction without changes in renal function

The aim of the present study was to investigate the effect of olmesartan medoxomil (OLM) on renal injury in mice with myocardial infarction (MI). A total of 33 male C57/BL/6 mice were divided into a sham surgery group (SHAM group), MI group (MI group) and OLM treatment group (OLM group). Experimental MI models were established in the mice of the MI and OLM groups by coronary artery ligation, and the mice in the OLM group were fed a daily dose of 10 mg/kg OLM for eight weeks. The results showed that MI induced a reduction in cardiac function and an increase in systolic blood pressure. In addition, increased periodic acid-Schiff (PAS) positive staining, combined with increased levels of angiotensin II (Ang II) in the plasma and kidneys, and increased expression levels of renin, angiotensin II type 1 receptor (AT1R) and angiotensinogen (AGT) in the kidney tissues was observed compared with those in the SHAM group. OLM treatment attenuated the injury by reducing the systolic blood pressure and PAS positive staining, and decreasing the expression levels of Ang II, renin, AT1R and AGT in the kidney compared with those in the MI group. It may be concluded that MI activates the intrarenal renin-angiotensin system and leads to glomerulosclerosis, and that OLM protects the kidney by inhibiting the effects of Ang II.