Hawthorn Herbal Preparation from Crataegus oxyacantha Attenuates In Vivo Carbon Tetrachloride -Induced Hepatic Fibrosis via Modulating Oxidative Stress and Inflammation

Hawthorn (HAW) is a herbal preparation extracted from Crataegus oxyacantha. HAW has cardioprotective, antioxidants, anti-inflammatory, and anti-hypotensive effects. HAW’s effect on hepatic fibrosis remains, however, unknown. This study evaluated the impact of HAW on carbon tetrachloride (CCl4)-induced hepatic fibrosis in rats and elucidated its mechanisms. HAW reduced liver index and the serum liver enzyme markers and reduced liver damage, and fibrosis as confirmed by histopathological scoring of hematoxylin-eosin staining. Collagen deposition was reduced in HAW group compared to CCl4 group as confirmed by Masson staining, hydroxyproline content, and both mRNA and protein levels of alpha-smooth muscle actin, collagen 1 and 3. HAW also down regulated the gene expressions of inflammatory markers including interleukin-IL-1β, tumor necrosis factor-α, transforming growth factor-β 1, nuclear factor kappa-B, and cyclooxygenase-2 and decreased the myeloperoxidase activity. The effects of HAW was also associated with decreased levels of hepatic oxidative stress markers (malondialdehyde and P.Carbonyl) and with increased activity of superoxide dismutase. Those effects are possibly mediated by blocking the pro-oxidant machinery and down regulating the inflammatory and profibrotic responses. Finally, chlorogenic acid, epicatechin, rutin, vitexin quercetin, and iso quercetin were identified as the major species of polyphenols of the HAW herbal preparation used here. Therefore, HAW’s potent protecting effects against liver fibrosis predicts a significant beneficial application.

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Sestrin 2 Attenuates Rat Hepatic Stellate Cell (HSC) Activation and Liver Fibrosis via an mTOR/AMPK-Dependent Mechanism

Cellular Physiology and Biochemistry ◽

10.1159/000495829 ◽

2018 ◽

Vol 51 (5) ◽

pp. 2111-2122 ◽

Cited By ~ 7

Author(s):

Yi-Bing Hu ◽

Xiao-Ting Ye ◽

Qing-Qing Zhou ◽

Rong-Quan Fu

Keyword(s):

Liver Fibrosis ◽

Protein Expression ◽

Hepatic Fibrosis ◽

Transforming Growth Factor ◽

Histopathological Examination ◽

Stellate Cell ◽

Smooth Muscle Actin ◽

Mrna Levels ◽

Alpha Smooth Muscle Actin

Background/Aims: Sestrin 2 is associated with the pathophysiology of several diseases. The aim of this study was to investigate the effects and potential mechanisms of Sestrin 2 in rat hepatic stellate cells (HSCs) during liver fibrogenesis. Methods: In this study, Sestrin 2 protein expression was detected in rat HSC-T6 cells challenged with transforming growth factor-β (TGF-β) and in mice treated with carbon tetrachloride (CCl4), a well-known model of hepatic fibrosis. Next, HSC-T6 cells and fibrotic mice were transfected with lentivirus. The mRNA expression levels of markers of liver fibrosis [alpha-smooth muscle actin (α-SMA) and collagen 1A1 (Col1A1)] were analyzed by quantitative reverse transcription–polymerase chain reaction (RT-PCR). Cell death and proliferation were evaluated by the MTT assay, and biochemical markers of liver damage in serum [alanine transaminase (ALT) and aspartate transaminase (AST)] were also measured using a biochemical analyzer. Histopathological examination was used to evaluate the degree of liver fibrosis, and protein expression [phospho-adenosine monophosphate-activated protein kinase (p-AMPK), AMPK, phospho-mammalian target of rapamycin (p-mTOR), and mTOR] was determined by western blotting. Results: We found that Sestrin 2 was elevated in both the HSC-T6 cell and hepatic fibrosis models. In vitro, overexpression of Sestrin 2 attenuated the mRNA levels of α-SMA and Col1A1, suppressed α-SMA protein expression, and modulated HSC-T6 cell proliferation. In vivo, overexpression of Sestrin 2 reduced the ALT and AST levels as well as the α-SMA and Col1A1 protein expression in the CCl4 model of liver fibrosis. Moreover, the degree of liver fibrosis was ameliorated. Interestingly, overexpression of Sestrin 2 increased p-AMPK but decreased p-mTOR protein expression. Conclusion: Our findings indicate that Sestrin 2 may attenuate the activation of HSCs and ameliorate liver fibrosis, most likely via upregulation of AMPK phosphorylation and suppression of the mTOR signaling pathway.

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Haematococcus pluvialis Carotenoids Enrich Fractions Ameliorate Liver Fibrosis Induced by Thioacetamide in Rats: Modulation of Metalloproteinase and Its Inhibitor

BioMed Research International ◽

10.1155/2021/6631415 ◽

2021 ◽

Vol 2021 ◽

pp. 1-16

Author(s):

Farouk K. El-Baz ◽

Abeer Salama ◽

Sami I. Ali ◽

Rania Elgohary

Keyword(s):

Liver Fibrosis ◽

Hepatic Fibrosis ◽

Transforming Growth Factor Beta ◽

Transforming Growth Factor ◽

Haematococcus Pluvialis ◽

Smooth Muscle Actin ◽

Alpha Smooth Muscle Actin ◽

Proinflammatory Mediators ◽

Growth Factor Beta ◽

Β Carotene

Hepatic fibrosis is a consequence of chronic liver diseases. Metalloproteinase and its inhibitor have crucial roles in the resolution of liver fibrosis. The current relevant study is aimed to evaluate the therapeutic effect of Haematococcus pluvialis (H. pluvialis) extract, astaxanthin-rich fraction, astaxanthin ester-rich fraction, and β-carotene-rich fraction as well as their mechanisms of action in curing hepatic fibrosis induced by thioacetamide (TAA). Liver fibrosis was induced using TAA (intraperitoneal injection, two times a week for 6 weeks), in a rat model and H. pluvialis extract (200 mg/kg), and other fractions (30 mg/kg) were orally administered daily for 4 weeks after the last TAA injection. Based on HPLC analysis, H. pluvialis extract contains β-carotene (12.95 mg/g, extract) and free astaxanthin (10.85 mg/g, extract), while HPLC/ESI-MS analysis revealed that H. pluvialis extract contains 28 carotenoid compounds including three isomers of free astaxanthin, α or β-carotene, lutein, 14 astaxanthin mono-esters, 5 astaxanthin di-esters, and other carotenoids. H. pluvialis and its fractions reduced liver enzymes, nitric oxide, collagen 1, alpha-smooth muscle actin, and transforming growth factor-beta as well as elevated catalase antioxidant activity compared to the TAA group. Also, H. pluvialis extract and its fractions exceedingly controlled the balance between metalloproteinase and its inhibitor, activated Kupffer cells proliferation, and suppressed liver apoptosis, necrobiosis, and fibrosis. These findings conclude that H. pluvialis extract and its fractions have an antifibrotic effect against TAA-induced liver fibrosis by regulating the oxidative stress and proinflammatory mediators, suppressing multiple profibrogenic factors, and modulating the metalloproteinase and its inhibitor pathway, recommending H. pluvialis extract and its fractions for the development of new effective medicine for treating hepatic fibrosis disorders.

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Hepatoprotective effect of Linagliptin against liver fibrosis induced by carbon tetrachloride in mice

Canadian Journal of Physiology and Pharmacology ◽

10.1139/cjpp-2020-0049 ◽

2020 ◽

Author(s):

Maaly Abd Elmaaboud ◽

Haidy Khattab ◽

Shahinaz Shalaby

Keyword(s):

Oxidative Stress ◽

Carbon Tetrachloride ◽

Liver Fibrosis ◽

Biochemical Parameters ◽

Transforming Growth Factor ◽

Corn Oil ◽

Smooth Muscle Actin ◽

Mammalian Target Of Rapamycin ◽

Metavir Score ◽

Tgf Β1

The current study aimed to investigate linagliptin for its potential role in the prevention of liver fibrosis progression. Balb-C mice were randomly allocated into 5 groups (10 each), (1) control, (2) mice were injected intraperitoneally with 50 μl carbon tetrachloride (CCl4) in corn oil in a dose of 0.6 μl /g 3 times a week for 4 weeks, (3) linagliptin was orally administered in a dose of 10 mg/kg/day simultaneously with CCl4, (4) silymarin was orally in a dose of 200 mg/kg/day concomitantly with CCl4, (5) linagliptin only. Hepatic injury was manifested in CCl4 group by elevation of biochemical parameters; alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), hepatic fibrosis was evident histopathologically by increased METAVIR score and immunostaining expression of α-smooth muscle actin (α-SMA), also, increased liver tissue oxidative stress parameters, transforming growth factor-β1 (TGF-β1) and mammalian target of rapamycin (mTOR). Linagliptin was able to stop the progression of liver fibrosis; evident histopathologically with reduced METAVIR score and α-SMA expression. The possible mechanism may be via suppression of oxidative stress, TGF-β1, and mTOR, this was associated with improvement of serum biochemical parameters; ALT and AST. In conclusion, linagliptin might help to protect the liver against persistent injury-related consequences.

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α-Lipoic acid modulates liver fibrosis: A cross talk between TGF-β1, autophagy, and apoptosis

Human & Experimental Toxicology ◽

10.1177/0960327119891212 ◽

2019 ◽

Vol 39 (4) ◽

pp. 440-450 ◽

Cited By ~ 1

Author(s):

WH El-Maadawy ◽

OA Hammam ◽

SH Seif el-Din ◽

NM El-Lakkany

Keyword(s):

Growth Factor ◽

Liver Fibrosis ◽

Hepatic Fibrosis ◽

Lipoic Acid ◽

Messenger Rna ◽

Transforming Growth Factor ◽

Smooth Muscle Actin ◽

Transforming Growth Factor Β1 ◽

Alpha Smooth Muscle Actin ◽

Tgf Β1

Autophagy and apoptosis are important players in the progression of hepatic fibrosis via activation of hepatic stellate cells (HSCs). Despite the recently depicted antifibrotic effects of alpha-lipoic acid (ALA), however, its modulatory effects on HSCs autophagy remain unverified. Our study aimed to elucidate the underlying antifibrotic mechanisms through which ALA mediates HSC autophagy and apoptosis. Liver fibrosis was induced via thioacetamide (TAA) intoxication in rats; TAA-intoxicated rats were treated with either silymarin or ALA. Effect of ALA on biochemical parameters and immunohistopathological examinations was measured and compared to silymarin. ALA restored normal hepatic architecture (S1 vs. S4), liver functions, hepatic glutathione, and transforming growth factor-β1 levels. ALA ameliorated hepatic levels of malondialdehyde, platelet-derived growth factor, tissue inhibitor metalloproteinases-1, hydroxyproline, and expression of alpha-smooth muscle actin. Moreover, ALA significantly reduced messenger RNA expression of LC3-II genes and triggered caspase-3 expression. Interestingly, ALA exhibited superior activities over silymarin regarding suppression of proliferation, activation and autophagy of HSCs, collagen deposition, and induction of HSCs apoptosis. In conclusion, treatment of TAA-intoxicated rats with ALA inhibited autophagy and induced apoptotic clearance of activated HSCs. Accordingly, this study provides mechanistic insights into the possible applicability of ALA in the treatment of hepatic fibrosis.

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Gypenosides Ameliorate Carbon Tetrachloride-Induced Liver Fibrosis by Inhibiting the Differentiation of Hepatic Progenitor Cells into Myofibroblasts

The American Journal of Chinese Medicine ◽

10.1142/s0192415x17500574 ◽

2017 ◽

Vol 45 (05) ◽

pp. 1061-1074 ◽

Cited By ~ 9

Author(s):

Jiamei Chen ◽

Xuewei Li ◽

Yonghong Hu ◽

Wei Liu ◽

Qun Zhou ◽

...

Keyword(s):

Carbon Tetrachloride ◽

Liver Fibrosis ◽

Progenitor Cells ◽

Transforming Growth Factor Beta ◽

Transforming Growth Factor ◽

Smooth Muscle Actin ◽

Cytokeratin 19 ◽

Type I ◽

Alpha Smooth Muscle Actin

Gypenosides (GPs), the predominant components of Gynostemma pentaphyllum, exert antifibrotic effects; however, the mechanisms underlying their ability to ameliorate liver fibrosis are unclear. Liver fibrosis was induced in C57BL/6 mice via subcutaneous injection of 10% carbon tetrachloride (CCl[Formula: see text] three times a week for two weeks. Then, CCl4 was administered in conjunction with intragastric GPs for another three weeks. For in vitro analyses, WB-F344, hepatatic progenitor cells (HPCs) were treated with transforming growth factor beta 1 (TGF-[Formula: see text]1) with or without GPs for 48[Formula: see text]h. The results showed that alanine aminotransferase (ALT) and aspartate transaminase (AST) activity, deposition of collagen, hydroxyproline content, and expression of alpha-smooth muscle actin ([Formula: see text]-SMA) and collagen type I (Col I) were significantly decreased after treatment with GPs ([Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text]). In the 5M CCl4 group, the expression of HPC markers, Sox9 and cytokeratin 19 (CK19), was significantly increased compared with the normal or GPs-treated group ([Formula: see text], [Formula: see text]). Immunostaining showed that the number of Sox9 and [Formula: see text]-SMA double-positive cells was higher in the 5M CCl4 group than in the normal group, but the addition of GPs caused this cell number to decrease. In WB-F344 cells, the expression of [Formula: see text]-SMA and Col I was significantly increased after treatment with TGF-[Formula: see text], whereas in the GPs treatment group, expression was markedly decreased ([Formula: see text]). The levels of TGF-[Formula: see text] and TGF-[Formula: see text]R1 were markedly reduced after GPs treatment both in vivo and in vitro. In conclusion, GPs ameliorated CCl4-induced liver fibrosis via the inhibition of TGF-[Formula: see text] signaling, consequently inhibiting the differentiation of HPCs into myofibroblasts.

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The AP-1 Transcription Factor Fosl-2 Regulates Autophagy in Cardiac Fibroblasts during Myocardial Fibrogenesis

International Journal of Molecular Sciences ◽

10.3390/ijms22041861 ◽

2021 ◽

Vol 22 (4) ◽

pp. 1861

Author(s):

Jemima Seidenberg ◽

Mara Stellato ◽

Amela Hukara ◽

Burkhard Ludewig ◽

Karin Klingel ◽

...

Keyword(s):

Transcription Factor ◽

Molecular Mechanisms ◽

Cardiac Fibrosis ◽

Type I Collagen ◽

Transforming Growth Factor ◽

Cardiac Fibroblasts ◽

Smooth Muscle Actin ◽

Beclin 1 ◽

Type I ◽

Alpha Smooth Muscle Actin

Background: Pathological activation of cardiac fibroblasts is a key step in development and progression of cardiac fibrosis and heart failure. This process has been associated with enhanced autophagocytosis, but molecular mechanisms remain largely unknown. Methods and Results: Immunohistochemical analysis of endomyocardial biopsies showed increased activation of autophagy in fibrotic hearts of patients with inflammatory cardiomyopathy. In vitro experiments using mouse and human cardiac fibroblasts confirmed that blockade of autophagy with Bafilomycin A1 inhibited fibroblast-to-myofibroblast transition induced by transforming growth factor (TGF)-β. Next, we observed that cardiac fibroblasts obtained from mice overexpressing transcription factor Fos-related antigen 2 (Fosl-2tg) expressed elevated protein levels of autophagy markers: the lipid modified form of microtubule-associated protein 1A/1B-light chain 3B (LC3BII), Beclin-1 and autophagy related 5 (Atg5). In complementary experiments, silencing of Fosl-2 with antisense GapmeR oligonucleotides suppressed production of type I collagen, myofibroblast marker alpha smooth muscle actin and autophagy marker Beclin-1 in cardiac fibroblasts. On the other hand, silencing of either LC3B or Beclin-1 reduced Fosl-2 levels in TGF-β-activated, but not in unstimulated cells. Using a cardiac hypertrophy model induced by continuous infusion of angiotensin II with osmotic minipumps, we confirmed that mice lacking either Fosl-2 (Ccl19CreFosl2flox/flox) or Atg5 (Ccl19CreAtg5flox/flox) in stromal cells were protected from cardiac fibrosis. Conclusion: Our findings demonstrate that Fosl-2 regulates autophagocytosis and the TGF-β-Fosl-2-autophagy axis controls differentiation of cardiac fibroblasts. These data provide a new insight for the development of pharmaceutical targets in cardiac fibrosis.

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Regulation of Cellular Senescence Is Independent from Profibrotic Fibroblast-Deposited ECM

Cells ◽

10.3390/cells10071628 ◽

2021 ◽

Vol 10 (7) ◽

pp. 1628

Author(s):

Kaj E. C. Blokland ◽

Habibie Habibie ◽

Theo Borghuis ◽

Greta J. Teitsma ◽

Michael Schuliga ◽

...

Keyword(s):

Growth Factor ◽

Cellular Senescence ◽

Transforming Growth Factor ◽

Cell Function ◽

Smooth Muscle Actin ◽

Transforming Growth Factor Β1 ◽

Tissue Growth ◽

Alveolar Epithelial Cells ◽

Lung Fibroblasts ◽

Alpha Smooth Muscle Actin

Idiopathic pulmonary fibrosis (IPF) is a devastating lung disease with poor survival. Age is a major risk factor, and both alveolar epithelial cells and lung fibroblasts in this disease exhibit features of cellular senescence, a hallmark of ageing. Accumulation of fibrotic extracellular matrix (ECM) is a core feature of IPF and is likely to affect cell function. We hypothesize that aberrant ECM deposition augments fibroblast senescence, creating a perpetuating cycle favouring disease progression. In this study, primary lung fibroblasts were cultured on control and IPF-derived ECM from fibroblasts pretreated with or without profibrotic and prosenescent stimuli, and markers of senescence, fibrosis-associated gene expression and secretion of cytokines were measured. Untreated ECM derived from control or IPF fibroblasts had no effect on the main marker of senescence p16Ink4a and p21Waf1/Cip1. However, the expression of alpha smooth muscle actin (ACTA2) and proteoglycan decorin (DCN) increased in response to IPF-derived ECM. Production of the proinflammatory cytokines C-X-C Motif Chemokine Ligand 8 (CXCL8) by lung fibroblasts was upregulated in response to senescent and profibrotic-derived ECM. Finally, the profibrotic cytokines transforming growth factor β1 (TGF-β1) and connective tissue growth factor (CTGF) were upregulated in response to both senescent- and profibrotic-derived ECM. In summary, ECM deposited by IPF fibroblasts does not induce cellular senescence, while there is upregulation of proinflammatory and profibrotic cytokines and differentiation into a myofibroblast phenotype in response to senescent- and profibrotic-derived ECM, which may contribute to progression of fibrosis in IPF.

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mTOR inhibitors potentially reduce TGF-β2-induced fibrogenic changes in trabecular meshwork cells

Scientific Reports ◽

10.1038/s41598-021-93580-3 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Nozomi Igarashi ◽

Megumi Honjo ◽

Makoto Aihara

Keyword(s):

Trabecular Meshwork ◽

Transforming Growth Factor ◽

Smooth Muscle Actin ◽

Mtor Inhibitors ◽

In Vivo Model ◽

Type I ◽

Fibrotic Response ◽

Alpha Smooth Muscle Actin

AbstractWe examined the effects of mTOR inhibitors on the fibrotic response induced by transforming growth factor-beta2 (TGF-β2) in cultured human trabecular meshwork (hTM) cells. TGF-β2-induced expression of fibronectin, collagen type I, alpha 1 chain (COL1A1), and alpha-smooth muscle actin (αSMA) in hTM cells was examined in the presence or absence of mTOR inhibitors using quantitative real-time polymerase chain reaction, Western blotting, and immunohistochemistry. The migration rates of hTM cells were examined in the presence of TGF-β2 with or without mTOR inhibitors. An in vitro study showed that the expression of fibronectin, COL1A1, and αSMA was upregulated by TGF-β2 treatment of hTM cells; such upregulation was significantly suppressed by mTOR inhibitors. The inhibitors significantly reduced the migration rate of TGF-β2-stimulated hTM cells. mTOR inhibitors may usefully reduce the fibrotic response of hTM cells and we may have to explore if it is also effective in in vivo model.

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A Clearance Period after Soluble Lead Nanoparticle Inhalation Did Not Ameliorate the Negative Effects on Target Tissues Due to Decreased Immune Response

International Journal of Molecular Sciences ◽

10.3390/ijms21228738 ◽

2020 ◽

Vol 21 (22) ◽

pp. 8738

Author(s):

Jana Dumková ◽

Tereza Smutná ◽

Lucie Vrlíková ◽

Bohumil Dočekal ◽

Daniela Kristeková ◽

...

Keyword(s):

Transforming Growth Factor Beta ◽

Inductively Coupled Plasma ◽

Structural Changes ◽

Transforming Growth Factor ◽

Smooth Muscle Actin ◽

Soluble Form ◽

Specific Response ◽

Alpha Smooth Muscle Actin ◽

Necrosis Factor Alpha ◽

Target Organs

The inhalation of metal (including lead) nanoparticles poses a real health issue to people and animals living in polluted and/or industrial areas. In this study, we exposed mice to lead(II) nitrate nanoparticles [Pb(NO3)2 NPs], which represent a highly soluble form of lead, by inhalation. We aimed to uncover the effects of their exposure on individual target organs and to reveal potential variability in the lead clearance. We examined (i) lead biodistribution in target organs using laser ablation and inductively coupled plasma mass spectrometry (LA-ICP-MS) and atomic absorption spectrometry (AAS), (ii) lead effect on histopathological changes and immune cells response in secondary target organs and (iii) the clearance ability of target organs. In the lungs and liver, Pb(NO3)2 NP inhalation induced serious structural changes and their damage was present even after a 5-week clearance period despite the lead having been almost completely eliminated from the tissues. The numbers of macrophages significantly decreased after 11-week Pb(NO3)2 NP inhalation; conversely, abundance of alpha-smooth muscle actin (α-SMA)-positive cells, which are responsible for augmented collagen production, increased in both tissues. Moreover, the expression of nuclear factor κB (NF-κB) and selected cytokines, such as tumor necrosis factor alpha (TNFα), transforming growth factor beta 1 (TGFβ1), interleukin 6(IL-6), IL-1α and IL-1β , displayed a tissue-specific response to lead exposure. In summary, diminished inflammatory response in tissues after Pb(NO3)2 NPs inhalation was associated with prolonged negative effect of lead on tissues, as demonstrated by sustained pathological changes in target organs, even after long clearance period.

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All-Trans Retinoic Acid Attenuates Fibrotic Processes by Downregulating TGF-β1/Smad3 in Early Diabetic Nephropathy

Biomolecules ◽

10.3390/biom9100525 ◽

2019 ◽

Vol 9 (10) ◽

pp. 525 ◽

Cited By ~ 1

Author(s):

Edith Sierra-Mondragon ◽

Rafael Rodríguez-Muñoz ◽

Carmen Namorado-Tonix ◽

Eduardo Molina-Jijon ◽

Daniel Romero-Trejo ◽

...

Keyword(s):

Diabetic Nephropathy ◽

Retinoic Acid ◽

Transforming Growth Factor ◽

Nuclear Translocation ◽

Smooth Muscle Actin ◽

Kidney Injury ◽

Alpha Smooth Muscle Actin ◽

Trans Retinoic Acid ◽

All Trans Retinoic Acid ◽

Tgf Β1

Diabetic nephropathy (DN) involves damage associated to hyperglycemia and oxidative stress. Renal fibrosis is a major pathologic feature of DN. The aim of this study was to evaluate anti-fibrogenic and renoprotective effects of all-trans retinoic acid (ATRA) in isolated glomeruli and proximal tubules of diabetic rats. Diabetes was induced by single injection of streptozotocin (STZ, 60 mg/Kg). ATRA (1 mg/Kg) was administered daily by gavage, from days 3–21 after STZ injection. ATRA attenuated kidney injury through the reduction of proteinuria, renal hypertrophy, increase in natriuresis, as well as early markers of damage such as β2-microglobulin, kidney injury molecule-1 (KIM-1), and neutrophil gelatinase-associated lipocalin (NGAL). The following parameters increased: macrophage infiltration, localization of alpha-smooth muscle actin (αSMA)-positive cells in renal tissue, and pro-fibrotic proteins such as transforming growth factor-β (TGF-β1), laminin beta 1 (LAM-β1), and collagens IV and I. Remarkably, ATRA treatment ameliorated these alterations and attenuated expression and nuclear translocation of Smad3, with increment of glomerular and tubular Smad7. The diabetic condition decreased expression of retinoic acid receptor alpha (RAR-α) through phosphorylation in serine residues mediated by the activation of c-Jun N-terminal kinase (JNK). ATRA administration restored the expression of RAR-α and inhibited direct interactions of JNK/RAR-α. ATRA prevented fibrogenesis through down-regulation of TGF-β1/Smad3 signaling.

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