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Background: The reactive oxygen species (ROS) and inflammation, a critical contributor to tissue damage, is well-known to be associated with various disease. The kidney is susceptible to hypoxia and vulnerable to ROS. Thus, the vicious cycle between oxidative stress and renal hypoxia critically contributes to the progression of chronic kidney disease and finally, end-stage renal disease. Thus, delivering therapeutic agents to the ROS-rich inflammation site and releasing the therapeutic agents is a feasible solution. Results: We developed a longer-circulating, inflammation-sensing, ROS-scavenging versatile nanoplatform by stably loading catalase-mimicking 1-dodecanethiol stabilized Mn3O4 (dMn3O4) nanoparticles inside ROS-sensitive nanomicelles (PTC), resulting in an ROS-sensitive nanozyme (PTC-M). Hydrophobic dMn3O4 nanoparticles were loaded inside PTC micelles to prevent premature release during circulation and act as a therapeutic agent by ROS-responsive release of loaded dMn3O4 once it reached the inflammation site. Conclusions: The findings of our study demonstrated the successful attenuation of inflammation and apoptosis in the IRI mice kidneys, suggesting that PTC-M nanozyme could possess promising potential in AKI therapy. This study paves the way for high-performance ROS depletion in treating various inflammation-related diseases. [ABSTRACT FROM AUTHOR]

Background information: Tubulointerstitial fibrosis is the end‐point of chronic kidney diseases. Tamoxifen, a selective oestrogen receptor (ER) modulator, attenuates renal fibrosis, by regulating the transforming growth factor (TGF)‐β/Smad signalling. Src and phosphoinositide 3‐kinase (PI3K)/Akt pathways play critical roles in the pathogenesis of renal fibrosis. However, the activation of the non‐canonical TGF‐β signalling in renal fibrosis after treatment with tamoxifen remains unclear. Renal fibrosis was induced by unilateral ureteral obstruction (UUO) in rats. Tamoxifen was orally administered after UUO. Additionally, HK‐2 cells were treated with tamoxifen in the presence or absence of TGF‐β1. The selective ER down‐regulator ICI and ER‐α silencing were used to confirm the involvement of ER‐α on the effect of tamoxifen on TGF‐β1‐stimulated fibrosis in HK‐2 cells. Results: Tamoxifen treatment ameliorated UUO‐induced renal fibrosis as shown by decreased expression of α‐smooth muscle actin (SMA), fibronectin and connective tissue growth factor (CTGF). The phosphorylation of Src, PI3K, Akt, mammalian target of rapamycin (mTOR) and p70S6K significantly decreased in UUO kidneys from tamoxifen‐treated animals. Tamoxifen dose‐dependently suppressed the TGF‐β1‐induced expression of α‐SMA and CTGF, and phosphorylation of Src, PI3K, Akt, mTOR and p70S6K in HK‐2 cells. These anti‐fibrotic effects were reversed by treatment with ICI and silencing of ER‐α. Moreover, inhibition of the PI3K/Akt and mTOR/p70S6K pathways was observed in HK‐2 cells co‐treated with PP1 (a Src kinase inhibitor) and tamoxifen. Conclusions: The anti‐fibrotic effects of tamoxifen are associated with the suppression of Src kinase function via ER‐α, followed by inhibition of the PI3K/Akt and mTOR/p70S6K signalling pathways. Significance: Our findings suggest that tamoxifen is a novel therapeutic option for the prevention and treatment of renal fibrosis. Research Article: Our results demonstrated that phosphorylation of Src kinase in the obstructive kidney medicates renal fibrosis by activation of PI3K/Akt and mTOR/p70S6K signalling pathway, and treatment of tamoxifen has anti‐fibrotic effect on renal fibrosis by suppressing these pathways. In addition, our in vitro results suggested that anti‐fibrotic effect and its downstream signalling pathway were attenuated by tamoxifen in an ER‐α‐dependent manner. However, at present, it remains difficult to determine whether tamoxifen acts as anti‐oestrogenic or oestrogenic effect in our study. [ABSTRACT FROM AUTHOR]

[Display omitted] ACE inhibitors or angiotensin II receptor blockers (ACEi/ARBs) have been a cornerstone of the management in kidney disease, but their use is often limited by undesired systemic effects, such as symptomatic hypotension. To minimize the extra-renal effects of ACEi/ARBs, we formulated hydrophobically modified glycol chitosan (HGC) nanomicelles releasing olmesartan (HGC-Olm) that specifically accumulated in the kidney, and investigated whether kidney-specific delivery of olmesartan by HGC nanomicelles could ameliorate organ damage in Col4a3 −/− mouse, a murine model of progressive chronic kidney disease mimicking human Alport syndrome. Ex vivo tracing demonstrated that intravenously injected HGC-Olm nanomicelles were specifically delivered to the kidney, with sustained release of olmesartan for more than 48 h. Contrary to the conventional delivery of olmesartan via oral route, injection of HGC-Olm nanomicelles did not alter blood pressure in Col4a3 −/− mice. Immunohistochemistry revealed that HGC nanomicelles were diffusely distributed from the cortex and glomeruli to the outer medulla, sparing the inner medulla. Phenotypic analysis showed that the attenuation of kidney fibrosis in the kidney of Col4a3 −/− mice by HGC-Olm nanomicelles was comparable to that noted with conventionally delivered olmesartan. Therefore, our results suggest that HGC-Olm nanomicelles could be a safe and effective alternative drug delivery system for kidney diseases. [ABSTRACT FROM AUTHOR]

Receptor tyrosine kinases (RTKs) play important roles in the pathogenic processes of kidney fibrosis. However, the pathophysiological roles of recepteur d'origine nantais (RON), one of the receptor tyrosine kinases, have not yet been defined. We investigated whether the activation or sequence-specific small interfering RNA (siRNA) suppression of RON could regulate epithelial mesenchymal transition (EMT) and the expression of pro-fibrotic markers, and its underlying molecular mechanisms. Stable cell lines and transient transfection for RON and the transfected cells of siRNA for RON were developed to investigate the molecular mechanisms in human kidney proximal tubular epithelial (HK-2) and interstitial fibroblasts (NRK49F) cells. RON overexpression induced EMT and increased expression of fibrosis-related proteins such as N-cadherin, vimentin, transforming growth factor-β (TGFβ), αSMA, and fibronectin in HK-2 and NRK49F cells. RON overexpression increased various RTKs and the phosphorylation of Src (Y416) and Smad, while inhibition of RON by siRNA attenuated the expression of EMT- and fibrosis-related proteins and decreased RTKs such as insulin-like growth factor receptor (IGFR), fibroblast growth factor receptor 1 (FGFR1), vascular endothelial growth factor receptor (VEGFR), and platelet-derived growth factor receptor (PDGFR), as well as the phosphorylation of Src and Smad pathways. siRNA silencing of Src also attenuated the expression of IGFR, FGFR1, VEGFR, and PDGFR. Inhibition of RON can exert an anti-fibrotic effect by the inhibition of EMT and other RTKs through control of Src and Smad pathways in HK-2 and NRK49F cells. [ABSTRACT FROM AUTHOR]

Aims: A neural mechanism regulating aquaporin (AQP) water channels in the kidney was investigated. Methods: Male Sprague-Dawley rats were used. Renal denervation was induced by painting the renal vessels with 10% phenol. The expression of AQP1–4 proteins was determined in the denervated and contralateral kidneys. The expression was also examined in rats which were renally denervated and subjected to water restriction or deoxycorticosterone acetate (DOCA)-salt treatment. Results: Following the unilateral denervation, tissue contents of norepinephrine were significantly decreased in the denervated kidney, while increased in the contralateral kidney. Accordingly, the expression of AQP1–4 proteins was decreased by 15–40% in the denervated kidney, and increased by 30–50% in the contralateral kidney. Immunohistochemistry of AQP2 confirmed its decreases in the denervated kidney and increases in the contralateral kidney. In bilaterally denervated rats, the urine flow increased along with decreased osmolarity. The water restriction increased the expression of AQP channels, however, the magnitude of which was lower in the denervated than in the contralateral kidney. Renal denervation decreased the degree of DOCA-salt hypertension, along with lower expression of AQP channels. Conclusion: It is suggested that the sympathetic nerve should play a specific excitatory role in the regulation of AQP channels in the kidney. Copyright © 2006 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]