Chronic exposure to environmental contaminant nonylphenol exacerbates adenine-induced chronic renal insufficiency: role of signaling pathways and therapeutic impact of rosuvastatin

Oxidized-LDL Deteriorated the Renal Residual Function and Parenchyma in CKD Rat through Upregulating Epithelial Mesenchymal Transition and Extracellular Matrix-Mediated Tubulointerstitial Fibrosis-Pharmacomodulation of Rosuvastatin

This study tested the hypothesis that intrarenal arterial transfusion of oxidized low-density lipoprotein (ox-LDL) jeopardized the residual renal function and kidney architecture in rat chronic kidney disease ((CKD), i.e., induced by 5/6 nephrectomy) that was reversed by rosuvastatin. Cell culture was categorized into A1 (NRK-52E cells), A2 (NRK-52E + TGF-β), A3 (NRK-52E + TGF-β + ox-LDL) and A4 (NRK-52E + TGF-β + ox-LD). The result of in vitro study showed that cell viability (at 24, 48 and 72 h), NRK-52E ox-LDL-uptake, protein expressions of epithelial−mesenchymal−transition (EMT) markers (i.e., p-Smad2/snail/α-SMA/FSP1) and cell migratory and wound healing capacities were significantly progressively increased from A1 to A4 (all p < 0.001). SD rats were categorized into group 1 (sham-operated control), group 2 (CKD), group 3 (CKD + ox-LDL/0.2 mg/rat at day 14 after CKD induction) and group 4 (CKD + ox-LDL-treated as group 3+ rosuvastatin/10 mg/kg/day by days 20 to 42 after CKD induction) and kidneys were harvested at day 42. The circulatory levels of BUN and creatinine, ratio of urine-protein to urine-creatinine and the protein expressions of the above-mentioned EMT, apoptotic (cleaved-caspase3/cleaved-PARP/mitochondrial-Bax) and oxidative-stress (NOX-1/NOX-2/oxidized-protein) markers were lowest in group 1, highest in group 3 and significantly higher in group 4 than in group 2 (all p < 0.0001). Histopathological findings demonstrated that the kidney injury score, fibrotic area and kidney injury molecule-1 (KIM-1) displayed an identical pattern, whereas the cellular expression of podocyte components (ZO-1/synaptopodin) exhibited an opposite pattern of EMT markers (all p < 0.0001). In conclusion, ox-LDL damaged the residual renal function and kidney ultrastructure in CKD mainly through augmenting oxidative stress, EMT and fibrosis that was remarkably reversed by rosuvastatin.

Systems analysis of the liver transcriptome in adult male zebrafish exposed to the non-ionic surfactant nonylphenol

Nonylphenol (NP) arises from the environmental degradation of nonylphenol ethoxylates. It is a ubiquitous environmental contaminant and has been detected at levels up to 167 nM in rivers in the United States. NP is an endocrine disruptor (ED) that can act as an agonist for estrogen receptors. The Adverse Outcome Pathway (AOP) framework defines an adverse outcome as the causal result of a series of molecular initiating events (MIEs) and key events (KEs) that lead to altered phenotypes. This study examined the liver transcriptome after a 21 day exposure to NP and 17β-estradiol (E2) by exploiting the zebrafish (Danio rerio) as a systems toxicology model. The goal of this study was to tease out non-estrogenic genomic signatures associated with NP exposure using DNA microarray and RNA sequencing. Our experimental design included E2 as a positive and potent estrogenic control in order to effectively compare and contrast the 2 compounds. This approach allowed us to identify hepatic transcriptomic perturbations that could serve as MIEs for adverse health outcomes in response to NP. Our results revealed that exposure to NP was associated with differential expression (DE) of genes associated with the development of steatosis, disruption of metabolism, altered immune response, and metabolism of reactive oxygen species, further highlighting NP as a chemical of emerging concern (CEC).

The cardioprotective effect of melatonin and exendin-4 treatment in a rat model of cardiorenal syndrome

We investigated the cardioprotective effect of melatonin (Mel) and exendin-4 (Ex4) treatment in a rat model of cardiorenal syndrome (CRS). Adult male SD rats (n=48) were randomly and equally divided into sham control (SC), dilated cardiomyopathy (DCM) (doxorubicin 7 mg/kg i.p. every five days/4 doses), CRS (defined as DCM+CKD) only, CRS-Mel (20 mg/kg/d), CRS-Ex4 (10 μg/kg/d), and CRS-Mel-Ex4 groups. In vitro results showed protein expressions of oxidative stress (NOX-1/NOX-2/oxidized protein), DNA/mitochondrial damage (γ-H2AX/cytosolic cytochrome c), apoptosis (cleaved caspase-3/PARP), and senescence (β-galactosidase cells) biomarkers were upregulated, whereas mitochondrial ATP level was decreased in doxorubicin/p-cresol-treated H9c2 cells that were revised by Mel and Ex4 treatments (all P<.001). By day 60, LVEF was highest in the SC and lowest in the CRS, significantly lower in the DCM than in other treatment groups, lower in the CRS-Mel and CRS-Ex4 than in the CRS-Mel-Ex4, and lower in the CRS-Mel than in the CRS-Ex4, whereas LV chamber size and histopathology score showed a pattern opposite to that of LVEF among all groups (all P<.001). Plasma creatinine level was highest in the CRS and lowest in the SC and progressively decreased from the CRS-Mel, CRS-Ex4, CRS-Mel-Ex4 to DCM (P<.0001). Protein expressions of inflammation (TNF-α/NF-κB/MMP-2/MMP-9/IL-1β), apoptosis/DNA damage (Bax/c-caspase-3/c-PARP/γ-H2AX), fibrosis (Smad3/TGF-β), oxidative stress (NOX-1/NOX-2/NOX-4/oxidized protein), cardiac hypertrophy/pressure overload (BNP/β-MHC), and cardiac integrity (Cx43/α-MHC) biomarkers in LV myocardium showed an opposite pattern compared to that of LVEF among all groups (all P<.001). Fibrotic area, DNA damage (γ-H2AX⁺ /53BP1⁺ CD90⁺ /XRCC1⁺ CD90⁺ ), and inflammation (CD14⁺ /CD68⁺ ) biomarkers in LV myocardium displayed a pattern opposite to that of LVEF among all groups (all P<.001). Combined melatonin and exendin-4 treatment suppressed CRS-induced deterioration of LVEF and LV remodeling.

Nonylphenol Toxicity Evaluation and Discovery of Biomarkers in Rat Urine by a Metabolomics Strategy through HPLC-QTOF-MS

Nonylphenol (NP) was quantified using liquid chromatography tandem mass spectrometry (LC-MS/MS) in the urine and plasma of rats treated with 0, 50, and 250 mg/kg/day of NP for four consecutive days. A urinary metabolomic strategy was originally implemented by high performance liquid chromatography time of flight mass spectrometry (HPLC-QTOF-MS) to explore the toxicological effects of NP and determine the overall alterations in the metabolite profiles so as to find potential biomarkers. It is essential to point out that from the observation, the metabolic data were clearly clustered and separated for the three groups. To further identify differentiated metabolites, multivariate analysis, including principal component analysis (PCA), orthogonal partial least-squares discriminant analysis (OPLS-DA), high-resolution MS/MS analysis, as well as searches of Metlin and Massbank databases, were conducted on a series of metabolites between the control and dose groups. Finally, five metabolites, including glycine, glycerophosphocholine, 5-hydroxytryptamine, malonaldehyde (showing an upward trend), and tryptophan (showing a downward trend), were identified as the potential urinary biomarkers of NP-induced toxicity. In order to validate the reliability of these potential biomarkers, an independent validation was performed by using the multiple reaction monitoring (MRM)-based targeted approach. The oxidative stress reflected by urinary 8-oxo-deoxyguanosine (8-oxodG) levels was elevated in individuals highly exposed to NP, supporting the hypothesis that mitochondrial dysfunction was a result of xenoestrogen accumulation. This study reveals a promising approach to find biomarkers to assist researchers in monitoring NP.

Cyclosporine-assisted adipose-derived mesenchymal stem cell therapy to mitigate acute kidney ischemia-reperfusion injury

Introduction

This study tested the hypothesis that cyclosporine (CsA)-supported syngeneic adipose-derived mesenchymal stem cell (ADMSC) therapy offered superior attenuation of acute ischemia–reperfusion (IR) kidney injury to either therapy alone.

Methods

Adult Sprague–Dawley rats (n = 40) were equally divided into group 1 (sham controls), group 2 (IR injury), group 3 (IR + CsA (20 mg/kg at 1 and 24 hours after procedure)), group 4 (syngeneic ADMSC (1.2×10⁶) at 1, 6 and 24 hours after procedure), and group 5 (IR + CsA-ADMSC).

Results

By 72 hours after the IR procedure, the creatinine level and the ratio of urine protein to creatinine were highest in group 2 and lowest in group 1, and significantly higher in groups 3 and 4 than in group 5 (all P <0.05 for inter-group comparisons), but showed no differences between groups 3 and 4 (P >0.05). The inflammatory biomarkers at mRNA (matrix metalloproteinase-9, RANTES, TNF-α), protein (TNF-α, NF-κB, intercellular adhesion molecule-1, platelet-derived growth factor), and cellular (CD68⁺) levels of IR kidney showed a similar pattern compared with that of creatinine in all groups (all P <0.05 for inter-group comparisons). The protein expressions of oxidative stress (oxidized protein), reactive oxygen species (NADPH oxidases NOX-1, NOX-2), apoptosis (Bcl-2–associated X protein, caspase-3 and poly(ADP-ribose) polymerase) and DNA damage (phosphorylated H2A histone family member X-positive, proliferating cell nuclear antigen-positive cells) markers exhibited a pattern similar to that of inflammatory mediators amongst all groups (all P <0.05 for inter-group comparisons). Expressions of antioxidant biomarkers at cellular (glutathione peroxidase, glutathione reductase, heme oxygenase-1 (HO-1)) and protein (NADPH dehydrogenase (quinone)-1, HO-1, endothelial nitric oxide synthase) levels, and endothelial progenitor cell markers (C-X-C chemokine receptor type 4-positive, stromal cell-derived factor-1α-positive) were lowest in groups 1 and 2, higher in groups 3 and 4, and highest in group 5 (all P <0.05 for inter-group comparisons).

Conclusion

Combination therapy using CsA plus ADMSCs offers improved protection against acute IR kidney injury.

NF-κB activation mediates crystal translocation and interstitial inflammation in adenine overload nephropathy

Adenine overload promotes intratubular crystal precipitation and interstitial nephritis. We showed recently that these abnormalities are strongly attenuated in mice knockout for Toll-like receptors-2, -4, MyD88, ASC, or caspase-1. We now investigated whether NF-κB activation also plays a pathogenic role in this model. Adult male Munich-Wistar rats were distributed among three groups: C (n = 17), receiving standard chow; ADE (n = 17), given adenine in the chow at 0.7% for 1 wk and 0.5% for 2 wk; and ADE + pyrrolidine dithiocarbamate (PDTC; n = 14), receiving adenine as above and the NF-κB inhibitor PDTC (120 mg·kg⁻¹·day⁻¹ in the drinking water). After 3 wk, widespread crystal deposition was seen in tubular lumina and in the renal interstitium, along with granuloma formation, collagen accumulation, intense tubulointerstitial proliferation, and increased interstitial expression of inflammatory mediators. Part of the crystals were segregated from tubular lumina by a newly formed cell layer and, at more advanced stages, appeared to be extruded to the interstitium. p65 nuclear translocation and IKK-α increased abundance indicated activation of the NF-κB system. PDTC treatment prevented p65 migration and normalized IKK-α, limited crystal shift to the interstitium, and strongly attenuated interstitial fibrosis/inflammation. These findings indicate that the complex inflammatory phenomena associated with this model depend, at least in part, on NF-κB activation, and suggest that the NF-κB system may become a therapeutic target in the treatment of chronic kidney disease.

Renal uptake of substrates for organic anion transporters Oat1 and Oat3 and organic cation transporters Oct1 and Oct2 is altered in rats with adenine-induced chronic renal failure

Chronic renal failure (CRF) leads to decreased drug renal clearance and glomerular filtration rate. However, little is known about renal tubular excretion and reabsorption in CRF. We examined transport activity of renal transporters using rats with adenine-induced CRF. We examined the effect of adenine-induced CRF on mRNA level, protein expression of transporters expressed in kidney by real-time polymerase chain reaction, and western blotting. In vivo kidney uptake clearances of benzylpenicillin and metformin, which are typical substrates for renal organic anion transporters Oat1 and Oat3 and organic cation transporters Oct1 and Oct2, respectively, were evaluated. Protein and mRNA expression levels of Oat1, Oat 3, Oct1, and Oct2 were significantly decreased in adenine-induced CRF rats. On the contrary, levels of P-glycoprotein and Mdr1b mRNA were significantly increased in adenine-induced CRF rats. The mRNA expression levels of Oatp4c1, Mate1, Urat1, Octn2, and Pept1 were significantly decreased. Kidney uptake clearance of benzylpenicillin and that of metformin were significantly decreased in adenine-induced CRF rats. Also, serum from CRF rats did not affect Oat1, Oat3, Oct1, and Oct2 function. In conclusion, our results indicate that adenine-induced CRF affects renal tubular handling of drugs, especially substrates of Oat1, Oat3, Oct1, and Oct2.