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The role of hypoxia-inducible factor-1 α in zinc oxide nanoparticle-induced nephrotoxicity in vitro and in vivo

View Article: PubMed Central - PubMed

ABSTRACT

Background: Zinc oxide nanoparticles (ZnO NPs) are used in an increasing number of products, including rubber manufacture, cosmetics, pigments, food additives, medicine, chemical fibers and electronics. However, the molecular mechanisms underlying ZnO NP nephrotoxicity remain unclear. In this study, we evaluated the potential toxicity of ZnO NPs in kidney cells in vitro and in vivo.

Results: We found that ZnO NPs were apparently engulfed by the HEK-293 human embryonic kidney cells and then induced reactive oxygen species (ROS) generation. Furthermore, exposure to ZnO NPs led to a reduction in cell viability and induction of apoptosis and autophagy. Interestingly, the ROS-induced hypoxia-inducible factor-1α (HIF-1α) signaling pathway was significantly increased following ZnO NPs exposure. Additionally, connective tissue growth factor (CTGF) and plasminogen activator inhibitor-1 (PAI-1), which are directly regulated by HIF-1 and are involved in the pathogenesis of kidney diseases, displayed significantly increased levels following ZnO NPs exposure in HEK-293 cells. HIF-1α knockdown resulted in significantly decreased levels of autophagy and increased cytotoxicity. Therefore, our results suggest that HIF-1α may have a protective role in adaptation to the toxicity of ZnO NPs in kidney cells. In an animal study, fluorescent ZnO NPs were clearly observed in the liver, lungs, kidneys, spleen and heart. ZnO NPs caused histopathological lesions in the kidney and increase in serum creatinine and blood urea nitrogen (BUN) which indicate possible renal possible damage. Moreover, ZnO NPs enhanced the HIF-1α signaling pathway, apoptosis and autophagy in mouse kidney tissues.

Conclusions: ZnO NPs may cause nephrotoxicity, and the results demonstrate the importance of considering the toxicological hazards of ZnO NP production and application, especially for medicinal use.

Electronic supplementary material: The online version of this article (doi:10.1186/s12989-016-0163-3) contains supplementary material, which is available to authorized users.

No MeSH data available.


Related in: MedlinePlus

In vivo biodistribution of ZnO NPs and histopathological analysis of kidneys after i.p. injection of ZnO NPs. a The images of liver, lungs, kidneys, spleen and heart under NIR illumination clearly demonstrate the presence of ZnO NPs in these organs. BALB/c mice were i.p. injected with red-NIR700-ZnO NPs (a dose of 10 mg/kg) and were sacrificed 6 h after injection. Various organs were collected, and fluorescence imaging was conducted using an IVIS 200 imaging system. b Concentration of ZnO NPs in tissues. The mice were i.p. injected with ZnO NPs (a dose of 10 mg/kg) and were sacrificed 6 h after injection. The concentrations of Zn in the lung, kidney, liver, spleen and heart were evaluated using an ICP-AES. *p < 0.05 versus control. c Histopathological kidney lesions were found in ZnO NP-treated mice. Tissue sections were stained with H&E and observed microscopically. The black arrows indicate tubular dilatation. The black arrowheads indicate the loss of brush borders and flattened tubular epithelium. The asterisks indicate the reduction of Bowman’s space and the increase in cellularity in glomeruli. BS, bowman space; G, glomerulus
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Fig6: In vivo biodistribution of ZnO NPs and histopathological analysis of kidneys after i.p. injection of ZnO NPs. a The images of liver, lungs, kidneys, spleen and heart under NIR illumination clearly demonstrate the presence of ZnO NPs in these organs. BALB/c mice were i.p. injected with red-NIR700-ZnO NPs (a dose of 10 mg/kg) and were sacrificed 6 h after injection. Various organs were collected, and fluorescence imaging was conducted using an IVIS 200 imaging system. b Concentration of ZnO NPs in tissues. The mice were i.p. injected with ZnO NPs (a dose of 10 mg/kg) and were sacrificed 6 h after injection. The concentrations of Zn in the lung, kidney, liver, spleen and heart were evaluated using an ICP-AES. *p < 0.05 versus control. c Histopathological kidney lesions were found in ZnO NP-treated mice. Tissue sections were stained with H&E and observed microscopically. The black arrows indicate tubular dilatation. The black arrowheads indicate the loss of brush borders and flattened tubular epithelium. The asterisks indicate the reduction of Bowman’s space and the increase in cellularity in glomeruli. BS, bowman space; G, glomerulus

Mentions: In vivo biodistribution of ZnO NPs can provide essential information on ZnO NP behavior post administration. We mimicked the medicinal use of ZnO NPs and thus used i.p. or i.v. injection for administration of ZnO NPs. To achieve this aim with high sensitivity, red-NIR700, a commonly used NIR fluorescent dye, was used with ZnO NPs to elucidate ZnO NP biodistribution in vivo. BALB/c mice were i.p. injected with red-NIR700-labeled ZnO NPs (at a dose of 10 mg/kg) and then sacrificed after 6 h. Our results showed that ZnO NPs can accumulate in the liver, lungs, kidneys, spleen and heart (Fig. 6a). In addition, the concentrations of Zn were evaluated using an ICP-AES (Fig. 6b). The Zn concentration in the lung, kidney, liver, spleen and heart showed a significant increase in comparison with the control groups. To further investigate the nephrotoxicity of ZnO NPs, the mice were i.p. or i.v. injected with varying concentrations of ZnO NPs. For the serum biochemical analysis, the activities of GOT, GPT, creatinine and BUN were significantly increased in the ZnO NP-treated mouse groups (Table 2 and Additional file 1: Table S1). ZnO NP treatments also decreased CCr levels (Additional file 1: Figure S1). Furthermore, the kidneys were sliced and stained with H&E. The histopathological lesions of the kidneys showed tubular dilatation, loss of brush borders and flattening of tubular epithelium, reduced Bowman’s space and increased cellularity in the glomeruli of ZnO NP-treated mice (Fig. 6c and Additional file 1: Figure S2).Fig. 6


The role of hypoxia-inducible factor-1 α in zinc oxide nanoparticle-induced nephrotoxicity in vitro and in vivo
In vivo biodistribution of ZnO NPs and histopathological analysis of kidneys after i.p. injection of ZnO NPs. a The images of liver, lungs, kidneys, spleen and heart under NIR illumination clearly demonstrate the presence of ZnO NPs in these organs. BALB/c mice were i.p. injected with red-NIR700-ZnO NPs (a dose of 10 mg/kg) and were sacrificed 6 h after injection. Various organs were collected, and fluorescence imaging was conducted using an IVIS 200 imaging system. b Concentration of ZnO NPs in tissues. The mice were i.p. injected with ZnO NPs (a dose of 10 mg/kg) and were sacrificed 6 h after injection. The concentrations of Zn in the lung, kidney, liver, spleen and heart were evaluated using an ICP-AES. *p < 0.05 versus control. c Histopathological kidney lesions were found in ZnO NP-treated mice. Tissue sections were stained with H&E and observed microscopically. The black arrows indicate tubular dilatation. The black arrowheads indicate the loss of brush borders and flattened tubular epithelium. The asterisks indicate the reduction of Bowman’s space and the increase in cellularity in glomeruli. BS, bowman space; G, glomerulus
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Fig6: In vivo biodistribution of ZnO NPs and histopathological analysis of kidneys after i.p. injection of ZnO NPs. a The images of liver, lungs, kidneys, spleen and heart under NIR illumination clearly demonstrate the presence of ZnO NPs in these organs. BALB/c mice were i.p. injected with red-NIR700-ZnO NPs (a dose of 10 mg/kg) and were sacrificed 6 h after injection. Various organs were collected, and fluorescence imaging was conducted using an IVIS 200 imaging system. b Concentration of ZnO NPs in tissues. The mice were i.p. injected with ZnO NPs (a dose of 10 mg/kg) and were sacrificed 6 h after injection. The concentrations of Zn in the lung, kidney, liver, spleen and heart were evaluated using an ICP-AES. *p < 0.05 versus control. c Histopathological kidney lesions were found in ZnO NP-treated mice. Tissue sections were stained with H&E and observed microscopically. The black arrows indicate tubular dilatation. The black arrowheads indicate the loss of brush borders and flattened tubular epithelium. The asterisks indicate the reduction of Bowman’s space and the increase in cellularity in glomeruli. BS, bowman space; G, glomerulus
Mentions: In vivo biodistribution of ZnO NPs can provide essential information on ZnO NP behavior post administration. We mimicked the medicinal use of ZnO NPs and thus used i.p. or i.v. injection for administration of ZnO NPs. To achieve this aim with high sensitivity, red-NIR700, a commonly used NIR fluorescent dye, was used with ZnO NPs to elucidate ZnO NP biodistribution in vivo. BALB/c mice were i.p. injected with red-NIR700-labeled ZnO NPs (at a dose of 10 mg/kg) and then sacrificed after 6 h. Our results showed that ZnO NPs can accumulate in the liver, lungs, kidneys, spleen and heart (Fig. 6a). In addition, the concentrations of Zn were evaluated using an ICP-AES (Fig. 6b). The Zn concentration in the lung, kidney, liver, spleen and heart showed a significant increase in comparison with the control groups. To further investigate the nephrotoxicity of ZnO NPs, the mice were i.p. or i.v. injected with varying concentrations of ZnO NPs. For the serum biochemical analysis, the activities of GOT, GPT, creatinine and BUN were significantly increased in the ZnO NP-treated mouse groups (Table 2 and Additional file 1: Table S1). ZnO NP treatments also decreased CCr levels (Additional file 1: Figure S1). Furthermore, the kidneys were sliced and stained with H&E. The histopathological lesions of the kidneys showed tubular dilatation, loss of brush borders and flattening of tubular epithelium, reduced Bowman’s space and increased cellularity in the glomeruli of ZnO NP-treated mice (Fig. 6c and Additional file 1: Figure S2).Fig. 6

View Article: PubMed Central - PubMed

ABSTRACT

Background: Zinc oxide nanoparticles (ZnO NPs) are used in an increasing number of products, including rubber manufacture, cosmetics, pigments, food additives, medicine, chemical fibers and electronics. However, the molecular mechanisms underlying ZnO NP nephrotoxicity remain unclear. In this study, we evaluated the potential toxicity of ZnO NPs in kidney cells in vitro and in vivo.

Results: We found that ZnO NPs were apparently engulfed by the HEK-293 human embryonic kidney cells and then induced reactive oxygen species (ROS) generation. Furthermore, exposure to ZnO NPs led to a reduction in cell viability and induction of apoptosis and autophagy. Interestingly, the ROS-induced hypoxia-inducible factor-1&alpha; (HIF-1&alpha;) signaling pathway was significantly increased following ZnO NPs exposure. Additionally, connective tissue growth factor (CTGF) and plasminogen activator inhibitor-1 (PAI-1), which are directly regulated by HIF-1 and are involved in the pathogenesis of kidney diseases, displayed significantly increased levels following ZnO NPs exposure in HEK-293 cells. HIF-1&alpha; knockdown resulted in significantly decreased levels of autophagy and increased cytotoxicity. Therefore, our results suggest that HIF-1&alpha; may have a protective role in adaptation to the toxicity of ZnO NPs in kidney cells. In an animal study, fluorescent ZnO NPs were clearly observed in the liver, lungs, kidneys, spleen and heart. ZnO NPs caused histopathological lesions in the kidney and increase in serum creatinine and blood urea nitrogen (BUN) which indicate possible renal possible damage. Moreover, ZnO NPs enhanced the HIF-1&alpha; signaling pathway, apoptosis and autophagy in mouse kidney tissues.

Conclusions: ZnO NPs may cause nephrotoxicity, and the results demonstrate the importance of considering the toxicological hazards of ZnO NP production and application, especially for medicinal use.

Electronic supplementary material: The online version of this article (doi:10.1186/s12989-016-0163-3) contains supplementary material, which is available to authorized users.

No MeSH data available.


Related in: MedlinePlus