Journal of Nephrology Advances

Journal of Nephrology Advances

Journal of Nephrology Advances

Current Issue Volume No: 1 Issue No: 2

Review Article Open Access Available online freely Peer Reviewed Citation

Action Mechanisms and Therapeutic Targets of Renal Fibrosis

1Department of Nephrology, Baoji Central Hospital, No. 8 Jiangtan Road, Baoji, Shaanxi 721008, China

Abstract

Renal fibrosis was a chronic and progressive process affecting kidneys in chronic kidney disease (CKD), regardless of cause. Although no effective targeted therapy yet existed to retard renal fibrosis, a number of important recent advances have highlighted the cellular and molecular mechanisms underlying the renal fibrosis. The advances including TGF-β/Smad pathway, oxidative stress and inflammation, hypoxia and gut microbiota-derived from uremic solutes were highlighted that could provide therapeutic targets. New therapeutic targets and strategies that are particularly promising for development of new treatments for patients with CKD were also highlighted.

Author Contributions
Received 26 Oct 2018; Accepted 04 Nov 2018; Published 12 Nov 2018;

Academic Editor: Ying-Yong Zhao, Northwest University, China.

Checked for plagiarism: Yes

Review by: Single-blind

Copyright ©  2018 Shi-Xing Ma, et al.

License
Creative Commons License     This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Competing interests

The authors have declared that no competing interests exist.

Citation:

Shi-Xing Ma, You-Quan Shang, Huan-Qiao Zhang, Wei Su (2018) Action Mechanisms and Therapeutic Targets of Renal Fibrosis. Journal of Nephrology Advances - 1(2):4-14. https://doi.org/10.14302/issn.2574-4488.jna-18-2443

Download as RIS, BibTeX, Text (Include abstract )

DOI 10.14302/issn.2574-4488.jna-18-2443

Introduction

Chronic kidney disease (CKD) had a high prevalence all over the world and was closely associated with high mortality 1, 2, 3. The prevalence of CKD was estimated to be 8-16% worldwide. In patients over 64 year old, the prevalence elevated to 23.4-35.8%, indicating increasing age contributed to elevate CKD. The yearly economic costs of medicine care for patients with CKD and or end-stage renal disease over age 65 were $60 billion, representing 24% of total Medicare expenditures in 2011 in America. According to the Kidney Disease Outcomes Quality Initiative, the international guidelines define and classify CKD as decreased renal function shown by glomerular filtration rate (GFR) of less than 60 mL/min per 1.73 m², or markers of kidney damage, or both, of at least three months duration, regardless of underlying cause 1. CKD were divided into five stages as follow: Stage 1: Kidney damage (pathological abnormalities or markers of damage including abnormalities in blood or urine tests or in imaging studies) with normal or raised glomerular filtration rate (≥90 mL per min per 1.73 m2); Stage 2: Glomerular filtration rate 60–89 mL per min per 1.73 m2 with evidence of kidney damage; Stage 3: Glomerular filtration rate 30–59 mL per min per 1.73 m2; Stage 4: Glomerular filtration rate 15–29 mL per min per 1.73 m2; Stage 5: End-stage renal failure; glomerular filtration rate <15 mL per min per 1.73 m21, 4, 5.

Renal fibrosis was characterized as a common endpoint of diverse CKD which resulted in functional damage ultimately leading to terminal renal failure 6, 7, 8, 9. Renal fibrosis is generally regarded as the dark side of tissue repair mechanisms. Fibrogenesis might be involved in the tubulointerstitium resulting in tubulointerstitial fibrosis, glomeruli resulting in glomerulosclerosis or the arterial vasculature resulting in atherosclerotic lesions 5, 10. Various action mechanisms were implicated in renal diseases and renal fibrosis 11, 12, 13, 14, 15, 16, 17, 18. Knowledge of the complex pathophysiological mechanisms contributed to CKD remains limited. In this review, we verify the critical roles of transforming growth factor-β (TGF-β)/Smad pathway, oxidative stress and inflammation, hypoxia and gut microbiota-derived from uremic solutes in the pathophysiology of CKD and renal fibrosis, summarize the action mechanisms of renal fibrosis, and discuss the effects of these mediators in the context of renal fibrosis.

TGF-β/Smad in Renal Fibrosis

TGF-β was essential for normal tissue development, repair and maintenance for organ functions. TGF-β1 was known as an antiinflammation cytokine 18. It produced anti-inflammatory effects through inhibition of mitogenesis and cytokine responses in glomerular cells and inhibiting infiltrating cells 18. Transforming growth factor-β (TGF-β1) knockout mice showed multi-organ inflammation and TGF-β1 deficient mice exhibited lethal inflammation and die within three weeks 19. Similarly, deletion of TGF-β1 or transforming growth factor-β receptor type II (TGFβRII) genes has been shown to cause autoimmune diseases 20, 21. Mice over-expressing latent TGF-β1 were protected against inflammation and renal fibrosis in obstructive nephropathy and glomerulonephritis 21, 22, 23. Although TGF-β-induced inhibition of NF-κB-mediated renal inflammation through induction of Smad7-dependent IκBα has been recently demonstrated 21, 23, the signaling action mechanisms of its anti-inflammatory action remain unclear. Yet, upregulated TGF-β1 was related to pathological disorders in many kidney diseases 24, 25.

There is extensive evidence pointing to TGF-β1 upregulation and its role in the pathogenesis of renal fibrosis in both animal models and patients with CKD 18, 26. TGF-β1 mediated progressive renal fibrosis by stimulating production and suppressing degradation of extracellular matrix (ECM). Moreover, TGF-β1 caused renal fibrosis by the transformation of tubular epithelial cells to myofibroblasts through epithelial-to-mesenchymal transition (EMT) 23. The central role of TGF-β1 on EMT and renal fibrosis has been confirmed by many experiments which indicated the ability of TGF-β1 blockade with decorin, neutralizing TGF-β antibody or anti-sense oligonucleotides to attenuate renal fibrosis 18. Direct evidence for the causal role of TGF-β1 in renal fibrosis is confirmed in mice over-expressing an active TGF-β1 form 27. TGF-β has been shown to serve a critical mediator in the pathogenesis of glomerulosclerosis in patients with glomerular diseases, such as lupus nephritis, immunoglobulin A nephropathy, membranous nephropathy, focal and segmental glomerulosclerosis and diabetic nephropathy. The upregulation of the three TGF-β isoforms and TGFβRI and TGFβRII has been uncovered in the glomeruli and tubulointerstitium in kidney diseases 28. Upregulation of TGF-β1 caused excessive ECM productions, reduced ECM-degrading proteinase activity and upregulated proteinase inhibitor, that resulted in excessive ECM deposition. In progressive podocyte-associated glomerular diseases, excessive TGF-β1 expression in the podocytes has been indicated the role of TGF-β1 in podocyte injury in patients with IgA nephropathy, focal and segmental glomerulosclerosis (FSGS) and diabetic nephropathy 29. Tubular and glomerular TGF-β expression was increased in early and late stages of diabetic nephropathy and inversely correlates with glycemic control in diabetic patients 30. TGF-β1 expression was stimulated by glomerular stretch and hyperglycemia in early stage, and by angiotensin II, advanced glycation end-product and platelet-derived growth factor 30. Angiotensin II has been demonstrated to raise expression of TGF-β1 and its receptors 31, 32.

Mounting studies have identified Smad2/3 as two major downstream mediators of the actions of TGF-β1 (Figure 1). In the context of renal fibrosis, Smad2/3 are activated in both patients and animal models with CKD of diverse etiologies such as hypertensive nephropathy 31, 33, 34, obstructive kidney disease 35, remnant kidney disease 36, 37, chronic renal allograft injury 38, diabetic nephropathy 39, 40, 41 and drug-induced nephropathy 42. Many fibrogenic genes including plasminogen activator inhibitor-1, tissue inhibitor of metalloproteinase-1, connective tissue growth factor, proteoglycans, integrins and collagens have been shown to be the downstream targets of TGF-β/Smad3 signaling 43. These observations demonstrate the central role of Smad3 in TGF-β/Smad signaling-mediated renal fibrosis.

Figure 1.The molecular mechanisms of renal fibrosis. Once an injury occurs in kidney, activated NF-κB and TGF-β/Smad pathways, as well as inhibited Nrf2 pathway were observed. The activation of NF-κB and TGF-β/Smad pathway induce inflammation and fibrosis, while the activation of Nrf2 pathway results in anti-inflammatory effects.
 The molecular mechanisms of renal fibrosis. Once an injury occurs in kidney, activated NF-κB and TGF-β/Smad pathways, as well as inhibited Nrf2 pathway were observed. The activation of NF-κB and                   TGF-β/Smad pathway induce inflammation and fibrosis, while the activation of Nrf2 pathway results in                  anti-inflammatory effects.

Many natural products have been widely used as anti-fibrotic agents 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56. Poricoic acid ZC, Poricoic acid ZD and poricoic acid ZE, isolated from the surface layer of Poria cocos, exhibited a strong inhibitory effect on renal fibrosis and podocyte injury. The findings showed that new RAS inhibitors poricoic acid ZC, poricoic acid ZD and poricoic acid ZE treatment significantly attenuated EMT production by inhibiting Wnt/β-catenin pathway activation and specific Smad3 phosphorylation by blocking the interaction of TGFβRI with Smad3 signaling in both TGF-β1- and angiotensin II-treated HK-2 cells as well as unilateral ureteral obstruction (UUO) mice 57. Similarly, renal fibrosis in a variety of animal models were mitigated via TGF-β/Smad pathways by administration of natural products, such as GQ5 58, curcumin 59, 60, arctigenin 61, resveratrol 62, sinomenine 63, berberine 64, 65, leonurine 66, rutin 67, bergenin 68, oxymatrine 69, 70, oleanolic acid 71, tanshinone IIA 72, astragaloside IV 73, 74, (+/-)-sinensilactam A 75 and epigallocatechin-3-gallate 76.

Oxidative Stress and Inflammation and Renal Fibrosis

Oxidative stress and inflammation played a central part in the pathogenesis and progression of CKD 77, 78, 79, 80, 81, 82. Renal fibrosis was a relatively common cause of CKD in humans. Rats or mice fed an adenine-containing diet exhibited severe renal fibrosis resembling that seen in humans 83. The renal fibrosis in this model was mediated by the renal tubular precipitation of dihydroxyadenine resulting in interstitial inflammatory cell infiltration, tubular epithelial cell injury, fibrosis and progressive deterioration of kidney function 84. Progressive renal disease was largely driven by inflammation and oxidative stress. Oxidative stress and inflammation were inseparably linked as they produced a vicious cycle in which oxidative stress triggered inflammation by many mechanisms including activation of the transcription factor kappa B which resulted in the activation and recruitment of immune cells 7 (Figure 1). Inflammation, in turn, triggered oxidative stress through production of reactive oxygen species and reactive nitrogen species by the activated leukocytes and resident cells. Together these events promote tissue damage by inflicting apoptosis, necrosis and fibrosis 85.

Under physiological conditions, oxidative stress gives rise to upregulation of the endogenous antioxidant and cytoprotective proteins and enzymes to prevent tissue injury. This process was mediated by the activation of the Nrf2 which regulated the basal activity and coordinated induction of numerous genes that encode various antioxidant and phase 2 detoxifying enzymes and related proteins 81. Nrf2 is an inactive complex in the cytoplasm by the repressor molecule, Keap1 which facilitated its ubiquitination (Figure 1). Keap1 contained reactive cysteine residues which function as intracellular redox sensors. Nuclear translocation of Nrf2 occurred by phosphorylation of its threonine or serine residues via upstream kinases, such as mitogen-activated protein kinases, protein kinase C, phosphatidylinositol-3-kinase/Akt, casein kinase-2 and PKR-like ER kinase 78. Regulation of cellular antioxidant and anti-inflammatory machinery by Nrf2 plays a central part in defense against oxidative stress. A number of studies have reported that the imbalance between NF-κB and Nrf2 pathways contributed to CKD and renal fibrosis 63, 77, 80, 81, 86.

Besides, inflammation could in the activation of immune cells, including macrophages, dendritic cells and T cells. These immune cells release profibrotic cytokines and growth factors that contribute to renal fibrosis 87, 88.

Hypoxia and Renal Fibrosis

The kidney was physiologically hypoxic despite its plentiful blood supply, because an oxygen shunt is present between arteries and veins. Therefore, it is reasonable to consider that erythropoietin-producing cells reside in the kidney, where they can sensitively detect hypoxia owing to anemia 89, 90, 91. Physiological hypoxia has been uncovered in mammals and in hypoxia-monitoring transgenic mice and rats produced by using hypoxia-inducible factor system. Expansive kidney hypoxia in CKD has also been verified in both patients and animal models. In CKD, hypoxia appeared in tubulointerstitium via multiple mechanisms. First, glomerulosclerosis resulted in a reduction of flow in downstream peritubular capillary, which further compromised by constriction of efferent arterioles of glomeruli and peritubular capillary owing to RAS activation. Second, the loss of peritubular capillaries occurred owing to fibrosis reduced blood perfusion. Third, excessive ECM deposition by fibrogenesis increased the distance between capillary and tubular, diminishing the efficiency of oxygen diffusion.

Upregulation of hypoxia-inducible factor 1α (HIF-1α) in transgenic mice upregulated vascular endothelial growth factor and platelet-derived growth factor-B expression and augmented endothelial cell proliferation. Although increased production and decreased deposition of ECM were observed in transgenic mice compared to control mice, they did not display renal injury or dysfunction 92. These results were consistent with study indicating that conditional knockout of HIF-1α in the proximal tubules lessened fibrosis in mouse UUO 89. Given that deposition of ECM was a part of repair processes unless it is uncontrolled, hypoxia-inducible factor activation by hypoxia in tubular cells mitigated renal injury by the upregulation of angiogenic and fibrogenic factors.

Uremic Solutes and Renal Fibrosis

Fibrosis was the final result of a complex signaling cascade of intracellular and intercellular and molecular responses initiated by organ injury 10. The fibrotic process and fibrotic-associated pathways are conserved between different organs. EMT has emerged as a mainly origin of collagenous matrix-producing myofibroblasts that contributed to the fibrotic response 46, 93, 94, 95. Renal fibrosis ends in uremic stage, yet uremia per se also further promoted the fibrogenesis owing to the direct biological effects of uremic toxins, such as, indoxyl sulfate (IS) and p-cresyl sulfate (p-CS). At least five uremic toxins showed a direct link to EMT and renal fibrosis 96, 97, 98, 99.

Uremic toxin IS was a small organic aromatic polycyclic anion derived from dietary tryptophan by gut microbiota that has widely been investigated in linking with CKD-associated cardiovascular disease 96, 100, 101, 102, and IS can induce vascular calcification and correlates with coronary artery disease and mortality 103. IS also contributed to a plethora of pathologies observed in dialysis patients, including tubulointerstitial inflammation and kidney damage 96. IS overload augmented the gene expression of tissue inhibitor of metalloproteinases-1, intercellular adhesion molecule-1, alpha-1 type I collagen, and TGF-β in the renal cortex of 5/6 nephrectomized rats 104. Moreover, IS stimulated the production of TGF-β in renal proximal tubular cells. Other study indicated that stimulation of HK-2 cells to IS resulted in a reactive oxygen species-mediated upregulation of plasminogen activator inhibitor-1, a downstream signaling mediator of the TGF-β signaling related to most aggressive kidney diseases 105. Furthermore, another study demonstrated that IS can increase α-SMA and TGF-β expression in HK-2 cells by activation of the (pro)renin receptor through reactive oxygen species-Stat3-NF-κB pathways 106. IS also activated the TGF-β signaling, as showed by an increased Smad2/3 phosphorylation 97, 107.

Although EMT contribution to fibrosis was controversial, phenotypic alterations reminiscent of EMT, also presented as epithelial phenotypic changes, might play an important role in the fibrogenesis and disease progression 108. A number of studies have demonstrated that IS induced EMT, as indicated by a downregulated expression of E-cadherin and zona occludens-1, and upregulated α-smooth muscle actin (α-SMA) expression in rat proximal tubular cells (NRK-52E) and rat kidneys 109. Furthermore, IS promoted EMT-associated transcription factor Snail expression, concurrent with an elevated expression of α-SMA and fibronectin and diminished E-cadherin expression in vitro97. Similar effects of IS have also been observed in human renal cell models 109.

In addition, genetic or microRNA-based mechanisms are also reported to inhibit renal fibrosis through modulating signaling pathways to prevent the progression of renal fibrosis during CKD. Knockdown of profibrotic factor Smad4 alleviated renal fibrosis in mice 110. microRNA-23b, microRNA-30e and microRNA -135a was significantly altered in CKD mice 111, 112, indicating microRNAs as biomarkers and therapeutic targets for CKD.

Conclusion

From the above it is clear that our knowledge of action mechanisms contributing to renal fibrosis had rapidly investigated and expanded over the several decades but we were still confused. Nevertheless, the novel knowledge obtained recently points to many new methods to combat renal fibrosis, at least partial reversal of fibrotic tubulointerstitial injury. Future investigation need to clarify whether individual mechanism contributes to all or at least many renal fibrosis models and would therefore be main candidates for therapeutic strategy and intervention at very early stage of fibrogenesis.

References

  1. 1.Webster A C, Nagler E V, Morton R L, Masson P.Chronic kidney disease.Lancet2017;389:. 1238-1252.
  1. 2.Hocher B, Adamski J. (2017) Metabolomics for clinical use and research in chronic kidney disease. Nat Rev Nephrol. 13, 269-284.
  1. 3.Zhang L, Long J, Jiang W.Trends in chronic kidney disease in China. The New England journal of medicine2016;375:. 905-906.
  1. 4.Stevens L A, Coresh J, Greene T, Levey A S. (2006) Assessing kidney function--measured and estimated glomerular filtration rate. The New England journal of medicine. 354-2473.
  1. 5.Wynn T A.Ramalingam TR (2012) Mechanisms of fibrosis: therapeutic translation for fibrotic disease. , Nature medicine; 18, 1028-1040.
  1. 6.Meng X M, PMK Tang, Li J, Lan H Y. (2015) TGF-β/Smad signaling in renal fibrosis. Front Physiol. 6-82.
  1. 7.Lan H Y. (2011) Diverse roles of TGF-beta/Smads in renal fibrosis and inflammation. International journal of biological sciences. 7, 1056-1067.
  1. 8.Loboda A, Sobczak M, Jozkowicz A, Dulak J. (2016) TGF-beta1/Smads and miR-21 in renal fibrosis and inflammation. Mediators of inflammation2016;. 8319283.
  1. 9.Higgins S P, Tang Y, Higgins C E. (2018) TGF-beta1/p53 signaling in renal fibrogenesis. Cellular signalling. 43, 1-10.
  1. 10.Hu H H, Chen D Q, Wang Y N.New insights into TGF-β/Smad signaling in tissue fibrosis. Chem Biol Interact2018;292: 76-83.
  1. 11.Afandi B, Bernieh B.Acute bilateral hydro nephrosis after the use of dapagliflozin. , Journal of Nephrology Advances2015;1: 42-47.
  1. 12.Andreucci M, Faga T, G De Sarro, Michael A.The toxicity of iodinated radiographic contrast agents in the clinical practice. , Journal of Nephrology Advances2015;1: 6-41.
  1. 13.Ehsan A, Lone A, Sabir O, Tareef N, Riaz S et al.Refractory anaemia with hyperoxalurea. , Journal of Nephrology Advances2015;1: 1-5.
  1. 14.Soni S S, Barnela S R, Saboo S S, Deshpande A V, Deshmukh S S et al.. Arteriovenous Fistula in A Patient with Aberrant Radial Artery. Journal of Nephrology Advances2016;1: 1-3.
  1. 15.G E B, Dami F, Hanin H, Kabbali N, Arrayhani M et al.Bedside lung ultrasound in the assessment of volume status in chronic hemodialysis patients. , Journal of Nephrology Advances2015;1: 48-57.
  1. 16.Edeling M, Ragi G, Huang S, Pavenstadt H, Susztak K. (2016) Developmental signalling pathways in renal fibrosis: the roles of Notch, Wnt and Hedgehog. Nat Rev Nephrol. 12, 426-439.
  1. 17.Kok H M, Falke L L, Goldschmeding R, Nguyen T Q. (2014) Targeting CTGF, EGF and PDGF pathways to prevent progression of kidney disease. Nat Rev Nephrol. 10, 700-711.
  1. 18.Meng X M, Nikolic-Paterson D J, Lan H Y. (2016) TGF-β: the master regulator of fibrosis. , Nat Rev Nephrol 12, 325-338.
  1. 19.Yaswen L, Kulkarni A B, Fredrickson T. (1996) Autoimmune manifestations in the transforming growth factor-β1 knockout mouse. Blood. 87, 1439-1445.
  1. 20.Li M O, Sanjabi S, Flavell R A. (2006) Transforming growth factor-β controls development, homeostasis, and tolerance of T cells by regulatory T cell-dependent and -independent mechanisms. Immunity. 25, 455-471.
  1. 21.Li M O, Wan Y Y, Flavell R A. (2007) T cell-produced transforming growth factor-β1 controls T cell tolerance and regulates Th1- and Th17-cell differentiation. Immunity. 26, 579-591.
  1. 22.Huang X R, Chung A C, Wang X J, Lai K N, Lan H Y. (2008) Mice overexpressing latent TGF-β1 are protected against renal fibrosis in obstructive kidney disease. American journal of physiology Renal physiology; 295:. 118-127.
  1. 23.Huang X R, Chung A C, Zhou L, Wang X J, Lan H Y. (2008) Latent TGF-β1 protects against crescentic glomerulonephritis. , Journal of the American Society of Nephrology : JASN 19, 233-242.
  1. 24.Budi E H, Duan D, Derynck R. (2017) Transforming Growth Factor-β Receptors and Smads: Regulatory Complexity and Functional Versatility. Trends in cell biology. 27, 658-672.
  1. 25.Sureshbabu A, Muhsin S A, Choi M E.TGF-β signaling in the kidney: profibrotic and protective effects. American journal of physiology Renal physiology 2016; 310:. 596-606.
  1. 26.Lan H Y. (2011) Diverse roles of TGF-β/Smads in renal fibrosis and inflammation. International journal of biological sciences. 7, 1056-1067.
  1. 27.Vanhove T, Goldschmeding R, Kuypers D. (2017) Kidney fibrosis: origins and interventions. Transplantation. 101, 713-726.
  1. 28.Shi Y, Massague J.Mechanisms of TGF-β signaling from cell membrane to the nucleus. Cell2003;113: 685-700.
  1. 29.Sharma K. (2011) Obesity, oxidative stress, and fibrosis in chronic kidney disease. Kidney Int Suppl. 4, 113-117.
  1. 30.Sharma K, McGowan T A. (2000) TGF-β in diabetic kidney disease: role of novel signaling pathways. Cytokine & growth factor reviews. 11, 115-123.
  1. 31.Liu Z, Huang X R, Chen H Y, Fung E, Liu J et al.Deletion of angiotensin-converting enzyme-2 promotes hypertensive nephropathy by targeting Smad7 for ubiquitin degradation. Hypertension (Dallas,Tex: 1979)2017; 70:. 822-830.
  1. 32.Nogueira A, Pires M J, Oliveira P A. (2017) Pathophysiological mechanisms of renal fibrosis: A review of animal models and therapeutic strategies. In vivo (Athens. , Greece 31, 1-22.
  1. 33.Wang W, Huang X R, Canlas E. (2006) Essential role of Smad3 in angiotensin II-induced vascular fibrosis. Circulation research. 98, 1032-1039.
  1. 34.Liu G X, Li Y Q, Huang X R.Smad7 inhibits AngII-mediated hypertensive nephropathy in a mouse model of hypertension. , Clinical science (London,England: 1979, 127-195.
  1. 35.Zhou B, Mu J, Gong Y. (2017) Brd4 inhibition attenuates unilateral ureteral obstruction-induced fibrosis by blocking TGF-β-mediated Nox4 expression. Redox biology. 11, 390-402.
  1. 36.Yang F, Huang X R, Chung A C, Hou C C, Lai K N et al.Essential role for Smad3 in angiotensin II-induced tubular epithelial-mesenchymal transition. The Journal of pathology2010; 221:. 390-401.
  1. 37.Huang X Z, Wen D, Zhang M.Sirt1 activation ameliorates renal fibrosis by inhibiting the TGF-β/Smad3 pathway. , Journal of cellular biochemistry2014; 115, 996-1005.
  1. 38.Wang Y Y, Jiang H, Pan J. (2017) Macrophage-to-myofibroblast transition contributes to interstitial fibrosis in chronic renal allograft Injury. , Journal of the American Society of Nephrology : JASN 28, 2053-2067.
  1. 39.Chung A C, Zhang H, Kong Y Z. (2010) Advanced glycation end-products induce tubular CTGF via TGF-β-independent Smad3 signaling. , Journal of the American Society of Nephrology : JASN 21, 249-260.
  1. 40.Chen H Y, Huang X R, Wang W. (2011) The protective role of Smad7 in diabetic kidney disease: mechanism and therapeutic potential. Diabetes. 60, 590-601.
  1. 41.Al-Rasheed N M, Al-Rasheed N M, Al-Amin M A.Fenofibrate attenuates diabetic nephropathy in experimental diabetic rat's model via suppression of augmented TGF-β1/Smad3 signaling pathway. Archives of physiology and biochemistry2016; 122:. 186-194.
  1. 42.Zhou L, Fu P, Huang X R.Mechanism of chronic aristolochic acid nephropathy: role of Smad3. American journal of physiology Renal physiology2010; 298:. 1006-1017.
  1. 43.Verrecchia F, Chu M L, Mauviel A.Identification of novel TGF-β /Smad gene targets in dermal fibroblasts using a combined cDNA microarray/promoter transactivation approach. The Journal of biological chemistry2001; 276:. 17058-17062.
  1. 44.Chen D Q, Feng Y L, Cao G, Zhao Y Y. (2018) Natural products as a source for antifibrosis therapy. Trends in pharmacological sciences. 39, 937-952.
  1. 45.Chen D Q, Hu H H, Wang Y N, Feng Y L, Cao G et al. (2018) Natural products for the prevention and treatment of kidney disease. Phytomedicine. 50, 50-60.
  1. 46.Davis F M, Stewart T A, Thompson E W, Monteith G R. (2014) Targeting EMT in cancer: opportunities for pharmacological intervention. Trends in pharmacological sciences. 35, 479-488.
  1. 47.Jiang W Y. (2005) Therapeutic wisdom in traditional Chinese medicine: a perspective from modern science. Trends in pharmacological sciences. 26, 558-563.
  1. 48.Zhang Z H, Li M H, Liu D. (2018) Rhubarb protect against tubulointerstitial fibrosis by inhibiting TGF-β/Smad pathway and improving abnormal metabolome in chronic kidney disease. Front Pharmacol. 9.
  1. 49.Dou F, Miao H, Wang J W. (2018) An integrated lipidomics and phenotype study reveals protective effect and biochemical mechanism of traditionally used Alisma orientale Juzepzuk in chronic renal disease. Front Pharmacol. 9-53.
  1. 50.Zhang Z H, Vaziri N D, Wei F, Cheng X L, Bai X et al. (2016) An integrated lipidomics and metabolomics reveal nephroprotective effect and biochemical mechanism of Rheum officinale in chronic renal failure. Sci Rep. 6, 22151.
  1. 51.Zhang Z H, Wei F, Vaziri N D. (2015) Metabolomics insights into chronic kidney disease and modulatory effect of rhubarb against tubulointerstitial fibrosis. Sci Rep. 5, 14472.
  1. 52.Chen H, Yang T, Wang M C, Chen D Q, Yang Y et al. (2018) Novel RAS inhibitor 25-O-methylalisol F attenuates epithelial-to-mesenchymal transition and tubulo-interstitial fibrosis by selectively inhibiting TGF-β-mediated Smad3 phosphorylation. Phytomedicine. 42, 207-218.
  1. 53.Wang M, Chen D Q, Wang M C. (2017) Poricoic acid ZA, a novel RAS inhibitor, attenuates tubulo-interstitial fibrosis and podocyte injury by inhibiting TGF-β/Smad signaling pathway. Phytomedicine. 36, 243-253.
  1. 54.Wang M, Chen D Q, Chen L. (2018) Novel RAS inhibitors poricoic acid ZG and poricoic acid ZH attenuate renal fibrosis via Wnt/β-catenin pathway and targeted phosphorylation of smad3 signaling. Journal of agricultural and food chemistry. 66, 1828-1842.
  1. 55.Zhao Y Y, Zhang L, Long F Y.UPLC-Q-TOF/HSMS/MS(E)-based metabonomics for adenine-induced changes in metabolic profiles of rat faeces and intervention effects of ergosta-4,6,8(14),22-tetraen-3-one. , Chem Biol Interact2013; 201, 31-38.
  1. 56.Chen L, Chen D Q, Wang M.Role of RAS/Wnt/ β-catenin axis activation in the pathogenesis of podocyte injury and tubulo-interstitial nephropathy. , Chem Biol Interact2017; 273, 56-72.
  1. 57.Wang M, Chen D Q, Chen L.Novel inhibitors of the cellular renin-angiotensin system components, poricoic acids, target Smad3 phosphorylation and Wnt/beta-catenin pathway against renal fibrosis. , Br J Pharmacol2018; 175, 2689-2708.
  1. 58.Ai J, Nie J, He J. (2015) GQ5 hinders renal fibrosis in obstructive nephropathy by selectively inhibiting TGF-β-induced Smad3 phosphorylation. , J Am Soc Nephrol 26, 1827-1838.
  1. 59.Sun X, Liu Y, Li C. (2017) Recent advances of Curcumin in the prevention and treatment of renal fibrosis. BioMed research international2017;. 2418671.
  1. 60.Zhou X, Zhang J, Xu C, Wang W.Curcumin ameliorates renal fibrosis by inhibiting local fibroblast proliferation and extracellular matrix deposition. , Journal of pharmacological sciences2014; 126, 344-350.
  1. 61.Li A, Zhang X, Shu M. (2017) Arctigenin suppresses renal interstitial fibrosis in a rat model of obstructive nephropathy. Phytomedicine : international journal of phytotherapy and phytopharmacology. 30, 28-41.
  1. 62.Chen C L, Chen Y H, Tai M C, Liang C M, Lu D W et al. (2017) Resveratrol inhibits transforming growth factor-β2-induced epithelial-to-mesenchymal transition in human retinal pigment epithelial cells by suppressing the Smad pathway. Drug Des Devel Ther. 11, 163-173.
  1. 63.Qin T, Yin S, Yang J.Sinomenine attenuates renal fibrosis through Nrf2-mediated inhibition of oxidative stress and TGFβ signaling. Toxicology and applied pharmacology 2016; 304: 1. 8.
  1. 64.Zhang X, He H, Liang D. (2016) Protective effects of Berberine on renal injury in streptozotocin (STZ)-induced diabetic mice. International journal of molecular sciences. 17.
  1. 65.Wang F M, Yang Y J, Ma L L, Tian X J, He Y Q. (2014) Berberine ameliorates renal interstitial fibrosis induced by unilateral ureteral obstruction in rats. Nephrology. , (Carlton, Vic) 19, 542-551.
  1. 66.Cheng H, Bo Y, Shen W. (2015) Leonurine ameliorates kidney fibrosis via suppressing TGF-β and NF-kappaB signaling pathway. in UUO mice. International immunopharmacology 25, 406-415.
  1. 67.Wang B, Liu D, Zhu Q H. (2016) Rutin ameliorates kidney interstitial fibrosis in rats with obstructive nephropathy. International immunopharmacology. 35, 77-84.
  1. 68.Yang J, Kan M, Wu G Y. (2016) Bergenin ameliorates diabetic nephropathy in rats via suppressing renal inflammation and TGF-β1-Smads pathway. Immunopharmacology and immunotoxicology. 38, 145-152.
  1. 69.Wang H W, Shi L, Xu Y P, Qin X Y, Wang Q Z. (2016) Oxymatrine inhibits renal fibrosis of obstructive nephropathy by downregulating the TGF-β1-Smad3 pathway. Renal failure. 38, 945-951.
  1. 70.Liu L, Wang Y, Yan R. (2016) Oxymatrine inhibits renal tubular EMT induced by high glucose via upregulation of SnoN and inhibition of TGF-β1/Smad signaling pathway. PloS one. 11, 0151986.
  1. 71.Lee E S, Kim H M, Kang J S. (2016) Oleanolic acid and N-acetylcysteine ameliorate diabetic nephropathy through reduction of oxidative stress and endoplasmic reticulum stress in a type 2 diabetic rat model. Nephrology, dialysis, transplantation : official publication of the European Dialysis and Transplant Association - European Renal Association. 31, 391-400.
  1. 72.Wang D T, Huang R H, Cheng X, Zhang Z H, Yang Y J et al. (2015) Tanshinone IIA attenuates renal fibrosis and inflammation via altering expression of TGF-β/Smad and NF-kappaB signaling pathway in 5/6 nephrectomized rats. International immunopharmacology. 26, 4-12.
  1. 73.Zhang L, Li Z, He W. (2015) Effects of Astragaloside IV against the TGF-β1-induced epithelial-to-mesenchymal transition in peritoneal mesothelial cells by promoting Smad 7 expression. Cellular physiology and biochemistry : international journal of experimental cellular physiology, biochemistry, and pharmacology. 37, 43-54.
  1. 74.Wang L, Chi Y F, Yuan Z T.Astragaloside IV inhibits renal tubulointerstitial fibrosis by blocking TGF-β/Smad signaling pathway in vivo and in vitro. Experimental biology and medicine. , (Maywood, NJ)2014;239: 1310-1324.
  1. 75.Luo Q, Tian L, L Di. (2015) (+/-)-Sinensilactam A, a pair of rare hybrid metabolites with Smad3 phosphorylation inhibition from Ganoderma sinensis. Organic letters. 17, 1565-1568.
  1. 76.Yin J, Liao S X, He Y. (2015) Dysbiosis of gut microbiota with reduced trimethylamine-N-oxide level in patients with large-artery atherosclerotic stroke or transient ischemic attack. , Journal of the American Heart Association 4.
  1. 77.Chen H, Cao G, Chen D Q. (2016) Metabolomics insights into activated redox signaling and lipid metabolism dysfunction in chronic kidney disease progression. Redox Biol. 10, 168-178.
  1. 78.Kansanen E, Kuosmanen S M, Leinonen H, Levonen A L. (2013) The Keap1-Nrf2 pathway: Mechanisms of activation and dysregulation in cancer. Redox Biol. 1, 45-49.
  1. 79.Milkovic L, Zarkovic N, Saso L. (2017) Controversy about pharmacological modulation of Nrf2 for cancer therapy. Redox Biol. 12, 727-732.
  1. 80.Chen D Q, Cao G, Chen H. (2017) Gene and protein expressions and metabolomics exhibit activated redox signaling and wnt/β-catenin pathway are associated with metabolite dysfunction in patients with chronic kidney disease. Redox Biol. 12, 505-521.
  1. 81.Ruiz S, Pergola P E, Zager R A, Vaziri N D. (2013) Targeting the transcription factor Nrf2 to ameliorate oxidative stress and inflammation in chronic kidney disease. Kidney Int. 83, 1029-1041.
  1. 82.Machowska A, Carrero J J, Lindholm B, Stenvinkel P.Therapeutics targeting persistent inflammation in chronic kidney disease. Translational research : the journal of laboratory and clinical medicine2016;167:. 204-213.
  1. 83.Zhao Y Y, Cheng X L, Wei F. (2012) Serum metabonomics study of adenine-induced chronic renal failure in rats by ultra performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry. Biomarkers. 17, 48-55.
  1. 84.Zhao Y Y, Cheng X L, Wei F. (2013) Intrarenal metabolomic investigation of chronic kidney disease and its TGF-β1 mechanism in induced-adenine rats using UPLC Q-TOF/HSMS/MS(E). , J Proteome Res 12, 2692-2703.
  1. 85.Zhao Y Y, Wang H L, Cheng X L. (2015) Metabolomics analysis reveals the association between lipid abnormalities and oxidative stress, inflammation, fibrosis, and Nrf2 dysfunction in aristolochic acid-induced nephropathy. Sci Rep. 5, 12936.
  1. 86.Trujillo J, Chirino Y I, Molina-Jijon E, Anderica-Romero A C, Tapia E et al. (2013) Renoprotective effect of the antioxidant curcumin: Recent findings. Redox Biol. 1, 448-456.
  1. 87.Humphreys B D. (2018) Mechanisms of Renal Fibrosis. Annual Review of Physiology. 80, 309-326.
  1. 88.Meng X M, Nikolic-Paterson D J, Lan H Y. (2014) Inflammatory processes in renal fibrosis. Nat Rev Nephrol. 10, 493-503.
  1. 89.Higgins D F, Kimura K, Bernhardt W M.Hypoxia promotes fibrogenesis in vivo via HIF-1 stimulation of epithelial-to-mesenchymal transition. , J Clin Invest2007;117: 3810-3820.
  1. 90.He L, Wei Q, Liu J. (2017) AKI on CKD: heightened injury, suppressed repair, and the underlying mechanisms. Kidney Int. 92, 1071-1083.
  1. 91.Takaori K, Yanagita M.Insights into the Mechanisms of the Acute Kidney Injury-to-Chronic Kidney Disease Continuum. , Nephron2016;134: 172-176.
  1. 92.Theilig F, Enke A K, Scolari B, Polzin D, Bachmann S et al.Tubular deficiency of von Hippel-Lindau attenuates renal disease progression in anti-GBM glomerulonephritis. The American journal of pathology2011;179:. 2177-2188.
  1. 93.Syn N, Wang L, Sethi G, Thiery J P, Goh B C. (2016) Exosome-mediated metastasis: from epithelial-mesenchymal transition to escape from immunosurveillance. Trends in pharmacological sciences. 37, 606-617.
  1. 94.Yeh Y C, Wei W C, Wang Y K, Lin S C, Sung J M et al.Transforming growth factor-β1 induces Smad3-dependent β1 integrin gene expression in epithelial-to-mesenchymal transition during chronic tubulointerstitial fibrosis. The American journal of pathology2010;177:. 1743-1754.
  1. 95.Xu J, Lamouille S, Derynck R. (2009) TGF-β-induced epithelial to mesenchymal transition. Cell Res. 19, 156-172.
  1. 96.Vanholder R, Schepers E, Pletinck A, Nagler E V, Glorieux G. (2014) The uremic toxicity of indoxyl sulfate and p-cresyl sulfate: a systematic review. , J Am Soc Nephrol 25, 1897-1907.
  1. 97.Sun C Y, Chang S C, Wu M S. (2012) Uremic toxins induce kidney fibrosis by activating intrarenal renin-angiotensin-aldosterone system associated epithelial-to-mesenchymal transition. PLoS One. 7, 34026.
  1. 98.Kim S H, Yu M A, Ryu E S, Jang Y H, Kang D H. (2012) Indoxyl sulfate-induced epithelial-to-mesenchymal transition and apoptosis of renal tubular cells as novel mechanisms of progression of renal disease. Laboratory investigation; a journal of technical methods and pathology. 92, 488-498.
  1. 99.Bolati D, Shimizu H, Niwa T. (2012) AST-120 ameliorates epithelial-to-mesenchymal transition and interstitial fibrosis in the kidneys of chronic kidney disease rats. , Journal of renal nutrition : the official journal of the Council on Renal Nutrition of the National Kidney Foundation 22, 176-180.
  1. 100.Lau W L, Savoj J, Nakata M B, Vaziri N D.Altered microbiome in chronic kidney disease: systemic effects of gut-derived uremic toxins. Clin Sci2018;132:. 509-522.
  1. 101.Brito J S, Borges N A, Dolenga C J, Carraro-Eduardo J C, Nakao L S et al. (2016) Is there a relationship between tryptophan dietary intake and plasma levels of indoxyl sulfate in chronic kidney disease patients on hemodialysis?. Jornal brasileiro de nefrologia : 'orgao oficial de Sociedades Brasileira e Latino-Americana de Nefrologia 38, 396-402.
  1. 102.Nazzal L, Roberts J, Singh P. (2017) Microbiome perturbation by oral vancomycin reduces plasma concentration of two gut-derived uremic solutes, indoxyl sulfate and p-cresyl sulfate, in end-stage renal disease. Nephrology, dialysis, transplantation : official publication of the European Dialysis and Transplant Association - European Renal Association. 32, 1809-1817.
  1. 103.Barreto F C, Barreto D V, Liabeuf S. (2009) Serum indoxyl sulfate is associated with vascular disease and mortality in chronic kidney disease patients. , Clinical journal of the American Society of Nephrology : CJASN 4, 1551-1558.
  1. 104.Miyazaki T, Ise M, Seo H, Niwa T. (1997) Indoxyl sulfate increases the gene expressions of TGF-beta 1, TIMP-1 and pro-alpha 1(I) collagen in uremic rat kidneys. Kidney Int Suppl. 62, 15-22.
  1. 105.Motojima M, Hosokawa A, Yamato H, Muraki T, Yoshioka T. (2003) Uremic toxins of organic anions up-regulate PAI-1 expression by induction of NF-kappaB and free radical in proximal tubular cells. Kidney Int. 63, 1671-1680.
  1. 106.Saito S, Shimizu H, Yisireyili M, Nishijima F, Enomoto A et al.Indoxyl sulfate-induced activation of (pro)renin receptor is involved in expression of TGF-beta1 and alpha-smooth muscle actin in proximal tubular cells. Endocrinology2014;155: 1899-1907.
  1. 107.Shimizu H, Yisireyili M, Nishijima F, Niwa T. (2013) Indoxyl sulfate enhances p53-TGF-beta1-Smad3 pathway in proximal tubular cells. American journal of nephrology. 37, 97-103.
  1. 108.Galichon P, Finianos S, Hertig A.EMT-MET in renal disease: should we curb our enthusiasm? Cancer letters2013;341:. 24-29.
  1. 109.Bolati D, Shimizu H, Higashiyama Y, Nishijima F, Niwa T. (2011) Indoxyl sulfate induces epithelial-to-mesenchymal transition in rat kidneys and human proximal tubular cells. , Am J Nephrol 34, 318-323.
  1. 110.Meng X-M, Huang X R, Xiao J. (2012) . Disruption of Smad4 impairs TGF-β/Smad3 and Smad7 transcriptional regulation during renal inflammation and fibrosis in vivo and in vitro. Kidney international 81, 266-279.
  1. 111.Nariman-Saleh-Fam Z, Bastami M, Ardalan M, Sharifi S, Hosseinian Khatib SM et al. (2018) Cell-free microRNA-148a is associated with renal allograft dysfunction: Implication for biomarker discovery. , Journal of Cellular Biochemistry; 0.
  1. 112.Ma Y, Shi J, Wang F. (2018) MiR-130b increases fibrosis of HMC cells by regulating the TGF-β1 pathway in diabetic nephropathy. , Journal of Cellular Biochemistry 0.

Cited by (13)

  1. 1.Yu Xiao-Yong, Sun Qian, Zhang Ya-Mei, Zou Liang, Zhao Ying-Yong, 2022, TGF-β/Smad Signaling Pathway in Tubulointerstitial Fibrosis, Frontiers in Pharmacology, 13(), 10.3389/fphar.2022.860588
  1. 2.Tan Yue-Qi, Wang Yan-Ni, Feng Hao-Yu, Guo Zhi-Yuan, Li Xia, et al, 2022, Host/microbiota interactions-derived tryptophan metabolites modulate oxidative stress and inflammation via aryl hydrocarbon receptor signaling, Free Radical Biology and Medicine, 184(), 30, 10.1016/j.freeradbiomed.2022.03.025
  1. 3.Feng Zhendong, Liu Wenbin, Jiang Han Xue, Dai Haoran, Gao Chang, et al, 2020, How Does Herbal Medicine Treat Idiopathic Membranous Nephropathy?, Frontiers in Pharmacology, 11(), 10.3389/fphar.2020.00994
  1. 4.Chen Yuan-Yuan, Chen Dan-Qian, Chen Lin, Liu Jing-Ru, Vaziri Nosratola D., et al, 2019, Microbiome–metabolome reveals the contribution of gut–kidney axis on kidney disease, Journal of Translational Medicine, 17(1), 10.1186/s12967-018-1756-4
  1. 5.Ren Li-Li, Li Xiao-Jun, Duan Ting-Ting, Li Zheng-Hai, Yang Jun-Zheng, et al, 2023, Transforming growth factor-β signaling: From tissue fibrosis to therapeutic opportunities, Chemico-Biological Interactions, 369(), 110289, 10.1016/j.cbi.2022.110289
  1. 6.Liu Xinhui, Huang Shiying, Wang Fochang, Zheng Lin, Lu Jiandong, et al, 2019, Huangqi-Danshen Decoction Ameliorates Adenine-Induced Chronic Kidney Disease by Modulating Mitochondrial Dynamics, Evidence-Based Complementary and Alternative Medicine, 2019(), 1, 10.1155/2019/9574045
  1. 7.Chen Dan-Qian, Wu Xia-Qing, Chen Lin, Hu He-He, Wang Yan-Ni, et al, 2020, Poricoic acid A as a modulator of TPH-1 expression inhibits renal fibrosis via modulating protein stability of β-catenin and β-catenin-mediated transcription, Therapeutic Advances in Chronic Disease, 11(), 204062232096264, 10.1177/2040622320962648
  1. 8.Zhao Ying-Yong, 2022, Recent advances of gut microbiota in chronic kidney disease patients, Exploration of Medicine, (), 260, 10.37349/emed.2022.00090
  1. 9.Gluba-Sagr Anna, Franczyk Beata, Rysz-Górzyńska Magdalena, Ławiński Janusz, Rysz Jacek, 2023, The Role of miRNA in Renal Fibrosis Leading to Chronic Kidney Disease, Biomedicines, 11(9), 2358, 10.3390/biomedicines11092358
  1. 10.Chen Lin, Cao Gang, Wang Ming, Feng Ya‐Long, Chen Dan‐Qian, et al, 2019, The Matrix Metalloproteinase‐13 Inhibitor Poricoic Acid ZI Ameliorates Renal Fibrosis by Mitigating Epithelial‐Mesenchymal Transition, Molecular Nutrition & Food Research, 63(13), 10.1002/mnfr.201900132
  1. 11.Lin Wei, Jiang Chen, Yu Hangxing, Wang Lingling, Li Jiaqi, et al, 2021, The effects of Fushen Granule on the composition and function of the gut microbiota during Peritoneal Dialysis–Related Peritonitis, Phytomedicine, 86(), 153561, 10.1016/j.phymed.2021.153561
  1. 12.Luo Liang-Pu, Suo Ping, Ren Li-Li, Liu Hong-Jiao, Zhang Yamei, et al, 2021, Shenkang Injection and Its Three Anthraquinones Ameliorates Renal Fibrosis by Simultaneous Targeting IƙB/NF-ƙB and Keap1/Nrf2 Signaling Pathways, Frontiers in Pharmacology, 12(), 10.3389/fphar.2021.800522
  1. 13.Wang Yan-Ni, Yang Chang-E, Zhang Dan-Dan, Chen Yuan-Yuan, Yu Xiao-Yong, et al, 2021, Long non-coding RNAs: A double-edged sword in aging kidney and renal disease, Chemico-Biological Interactions, 337(), 109396, 10.1016/j.cbi.2021.109396