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Smad7 protects against chronic aristolochic acid nephropathy in mice.

Dai XY, Zhou L, Huang XR, Fu P, Lan HY - Oncotarget (2015)

Bottom Line: However, treatment for chronic AAN remains ineffective.Importantly, we also found that overexpression of Smad7 locally in the kidneys with established chronic AAN was capable of attenuating progressive chronic AAN by inactivating TGF-β/Smad3-medated renal fibrosis and NF-κB-driven renal inflammation.In conclusion, Smad7 plays a protective role in the pathogenesis of chronic AAN and overexpression of Smad7 may represent a novel therapeutic potential for chronic AAN.

View Article: PubMed Central - PubMed

Affiliation: Department of Medicine and Therapeutics, Li Ka Shing Institute of Health Sciences, and Shenzhen Research Institute, The Chinese University of Hong Kong, Hong Kong, China.

ABSTRACT
Chronic Aristolochic Acid Nephropathy (AAN) is a progressive chronic kidney disease related to herb medicine. However, treatment for chronic AAN remains ineffective. We report here that Smad7 is protective and has therapeutic potential for chronic AAN. In a mouse model of chronic AAN, progressive renal injury was associated with a loss of renal Smad7 and disruption of Smad7 largely aggravated the severity of chronic AAN as demonstrated by a significant increase in levels of 24-hour urinary protein excretion, serum creatinine, and progressive renal fibrosis and inflammation. In contrast, restored Smad7 locally in the kidneys of Smad7 knockout mice prevented the progression of chronic AAN. Further studies revealed that worsen chronic AAN in Smad7 knockout mice was associated with enhanced activation of TGF-β/Smad3 and NF-κB signaling pathways, which was reversed when renal Smad7 was restored. Importantly, we also found that overexpression of Smad7 locally in the kidneys with established chronic AAN was capable of attenuating progressive chronic AAN by inactivating TGF-β/Smad3-medated renal fibrosis and NF-κB-driven renal inflammation. In conclusion, Smad7 plays a protective role in the pathogenesis of chronic AAN and overexpression of Smad7 may represent a novel therapeutic potential for chronic AAN.

No MeSH data available.


Related in: MedlinePlus

Restored renal Smad7 blocks TGF-β/Smad and NF-κB signaling in the kidney of Smad7 KO mice with chronic AAN at day 42 after induction of AANA: Phosphorylated Smad2/3 nuclear translocation by immunohistochemistry. B: Smad7 expression and phosphorylated Smad3 (P-Smad3) by western blotting. C: Phosphorylated NF-κB/p65 nuclear translocation by immunohistochemistry. D: Phosphorylation of IκBα and NF-κB/p65 by western blotting. Note that compared to Smad7 KO mice with chronic AAN without treatment (AAN-UT) or treated with vector control (AAN-VC), restored renal Smad7 in the AAN kidney of Smad7 KO mice (AAN-Smad7) largely blocks a marked activation of both TGF-β/Smad3 and NF-κB signaling. Data are expressed as mean ± SE for groups of 6 mice. *P < 0.05, **P < 0.01, ***P < 0.001 compared with saline control mice. #P < 0.05, ##P < 0.01, ###P < 0.001 compared with Smad7 KO mice with chronic AAN treated with or without VC. Magnification: x400.
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Figure 6: Restored renal Smad7 blocks TGF-β/Smad and NF-κB signaling in the kidney of Smad7 KO mice with chronic AAN at day 42 after induction of AANA: Phosphorylated Smad2/3 nuclear translocation by immunohistochemistry. B: Smad7 expression and phosphorylated Smad3 (P-Smad3) by western blotting. C: Phosphorylated NF-κB/p65 nuclear translocation by immunohistochemistry. D: Phosphorylation of IκBα and NF-κB/p65 by western blotting. Note that compared to Smad7 KO mice with chronic AAN without treatment (AAN-UT) or treated with vector control (AAN-VC), restored renal Smad7 in the AAN kidney of Smad7 KO mice (AAN-Smad7) largely blocks a marked activation of both TGF-β/Smad3 and NF-κB signaling. Data are expressed as mean ± SE for groups of 6 mice. *P < 0.05, **P < 0.01, ***P < 0.001 compared with saline control mice. #P < 0.05, ##P < 0.01, ###P < 0.001 compared with Smad7 KO mice with chronic AAN treated with or without VC. Magnification: x400.

Mentions: To further confirm the protective role of Smad7 in chronic AAN, we locally delivered an inducible Smad7 gene into the kidneys of Smad7 KO mice via tail vein using an ultrasound-microbubble-mediated technique as previously described [14-17]. We found that restored renal Smad7 largely prevented AA-induced chronic AAN such as dilated and bared tubular basement membrane changes in tubulointerstitium and attenuated 24h proteinuria and serum creatinine when compared with those treated with or without empty vector control (Fig. 4). Immunohistochemistry, western blot, and real-time PCR also showed that restored renal Smad7 blocked AA-induced severe renal fibrosis such as upregulation of collagen I and α-SMA and inhibited renal inflammation including F4/80+ macrophages and CD3+ T cells and upregulation of MCP-1 and TNFα (Fig. 5 and Figs. S4 and S5). Western blot analysis clearly revealed that the inhibitory effect of Smad7 on renal fibrosis and inflammation was associated with the restoration of exogenous Smad7, thereby inhibiting TGF-β/Smad signaling by suppressing the phosphorylation of Smad3 and upregulation of TGF-β1 (Fig. 6A and 6B and Fig.S6) and attenuating NF-κB signaling by lowering phosphorylated IκBα and NF-κB/p65 in the AAN kidney (Fig. 6C and 6D).


Smad7 protects against chronic aristolochic acid nephropathy in mice.

Dai XY, Zhou L, Huang XR, Fu P, Lan HY - Oncotarget (2015)

Restored renal Smad7 blocks TGF-β/Smad and NF-κB signaling in the kidney of Smad7 KO mice with chronic AAN at day 42 after induction of AANA: Phosphorylated Smad2/3 nuclear translocation by immunohistochemistry. B: Smad7 expression and phosphorylated Smad3 (P-Smad3) by western blotting. C: Phosphorylated NF-κB/p65 nuclear translocation by immunohistochemistry. D: Phosphorylation of IκBα and NF-κB/p65 by western blotting. Note that compared to Smad7 KO mice with chronic AAN without treatment (AAN-UT) or treated with vector control (AAN-VC), restored renal Smad7 in the AAN kidney of Smad7 KO mice (AAN-Smad7) largely blocks a marked activation of both TGF-β/Smad3 and NF-κB signaling. Data are expressed as mean ± SE for groups of 6 mice. *P < 0.05, **P < 0.01, ***P < 0.001 compared with saline control mice. #P < 0.05, ##P < 0.01, ###P < 0.001 compared with Smad7 KO mice with chronic AAN treated with or without VC. Magnification: x400.
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Figure 6: Restored renal Smad7 blocks TGF-β/Smad and NF-κB signaling in the kidney of Smad7 KO mice with chronic AAN at day 42 after induction of AANA: Phosphorylated Smad2/3 nuclear translocation by immunohistochemistry. B: Smad7 expression and phosphorylated Smad3 (P-Smad3) by western blotting. C: Phosphorylated NF-κB/p65 nuclear translocation by immunohistochemistry. D: Phosphorylation of IκBα and NF-κB/p65 by western blotting. Note that compared to Smad7 KO mice with chronic AAN without treatment (AAN-UT) or treated with vector control (AAN-VC), restored renal Smad7 in the AAN kidney of Smad7 KO mice (AAN-Smad7) largely blocks a marked activation of both TGF-β/Smad3 and NF-κB signaling. Data are expressed as mean ± SE for groups of 6 mice. *P < 0.05, **P < 0.01, ***P < 0.001 compared with saline control mice. #P < 0.05, ##P < 0.01, ###P < 0.001 compared with Smad7 KO mice with chronic AAN treated with or without VC. Magnification: x400.
Mentions: To further confirm the protective role of Smad7 in chronic AAN, we locally delivered an inducible Smad7 gene into the kidneys of Smad7 KO mice via tail vein using an ultrasound-microbubble-mediated technique as previously described [14-17]. We found that restored renal Smad7 largely prevented AA-induced chronic AAN such as dilated and bared tubular basement membrane changes in tubulointerstitium and attenuated 24h proteinuria and serum creatinine when compared with those treated with or without empty vector control (Fig. 4). Immunohistochemistry, western blot, and real-time PCR also showed that restored renal Smad7 blocked AA-induced severe renal fibrosis such as upregulation of collagen I and α-SMA and inhibited renal inflammation including F4/80+ macrophages and CD3+ T cells and upregulation of MCP-1 and TNFα (Fig. 5 and Figs. S4 and S5). Western blot analysis clearly revealed that the inhibitory effect of Smad7 on renal fibrosis and inflammation was associated with the restoration of exogenous Smad7, thereby inhibiting TGF-β/Smad signaling by suppressing the phosphorylation of Smad3 and upregulation of TGF-β1 (Fig. 6A and 6B and Fig.S6) and attenuating NF-κB signaling by lowering phosphorylated IκBα and NF-κB/p65 in the AAN kidney (Fig. 6C and 6D).

Bottom Line: However, treatment for chronic AAN remains ineffective.Importantly, we also found that overexpression of Smad7 locally in the kidneys with established chronic AAN was capable of attenuating progressive chronic AAN by inactivating TGF-β/Smad3-medated renal fibrosis and NF-κB-driven renal inflammation.In conclusion, Smad7 plays a protective role in the pathogenesis of chronic AAN and overexpression of Smad7 may represent a novel therapeutic potential for chronic AAN.

View Article: PubMed Central - PubMed

Affiliation: Department of Medicine and Therapeutics, Li Ka Shing Institute of Health Sciences, and Shenzhen Research Institute, The Chinese University of Hong Kong, Hong Kong, China.

ABSTRACT
Chronic Aristolochic Acid Nephropathy (AAN) is a progressive chronic kidney disease related to herb medicine. However, treatment for chronic AAN remains ineffective. We report here that Smad7 is protective and has therapeutic potential for chronic AAN. In a mouse model of chronic AAN, progressive renal injury was associated with a loss of renal Smad7 and disruption of Smad7 largely aggravated the severity of chronic AAN as demonstrated by a significant increase in levels of 24-hour urinary protein excretion, serum creatinine, and progressive renal fibrosis and inflammation. In contrast, restored Smad7 locally in the kidneys of Smad7 knockout mice prevented the progression of chronic AAN. Further studies revealed that worsen chronic AAN in Smad7 knockout mice was associated with enhanced activation of TGF-β/Smad3 and NF-κB signaling pathways, which was reversed when renal Smad7 was restored. Importantly, we also found that overexpression of Smad7 locally in the kidneys with established chronic AAN was capable of attenuating progressive chronic AAN by inactivating TGF-β/Smad3-medated renal fibrosis and NF-κB-driven renal inflammation. In conclusion, Smad7 plays a protective role in the pathogenesis of chronic AAN and overexpression of Smad7 may represent a novel therapeutic potential for chronic AAN.

No MeSH data available.


Related in: MedlinePlus