key: cord-0699841-lrhndiel
authors: DiNicolantonio, James J; McCarty, Mark F; Barroso-Aranda, Jorge; Assanga, Simon; Lujan, Lidianys Maria Lewis; O'Keefe, James H
title: A nutraceutical strategy for downregulating TGFβ signalling: prospects for prevention of fibrotic disorders, including post-COVID-19 pulmonary fibrosis
date: 2021-04-20
journal: Open Heart
DOI: 10.1136/openhrt-2021-001663
sha: 4ef6ebd78323ec498b371c8e079522fb7f7b5b46
doc_id: 699841
cord_uid: lrhndiel

nan

OVERVIEW OF TRANSFORMING GROWTH FACTOR-BETA SIGNALLING Upregulated transforming growth factorbeta (TGFβ) signalling, driving mesenchymal cells to increase their production of ground substance and undergo a transition to a myofibroblast phenotype, is believed to play a pathogenic role in diverse fibrotic disorders, including benign prostatic hyperplasia, scleroderma, pulmonary fibrosis, glomerulosclerosis, tubulointerstial fibrosis, hepatic fibrosis, open angle glaucoma, Peyronie's disease and the cardiac fibrosis associated with cardiac hypertrophy and heart failure. [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] [20] It should follow that safe, practical measures which downregulate such signalling may have potential for the prevention and control of these syndromes. Nutraceutical measures with this property have particular promise, as they might be employed for primary prevention. This issue is now of particular interest, as pulmonary fibrosis is emerging as a not-uncommon long-term complication of COVID-19. 21 22 TGFβ signalling commences when this ligand binds to the type II TGFβ receptor (TβRII), inducing its association with the type I receptor (TβRI) to form a heterotrimer complex. The constitutive serine-threonine kinase activity of TβRII then phosphorylates TβRI, activating its dual-specificity kinase activity. Smad2 or Smad3 then bind to TβRI, which phosphorylates it on a serine. This phosphorylation enables Smad2/3 to complex with Smad4, forming a heterodimer which translates to the nucleus to serve as a transcription factor to promote expression of TGFβ-inducible genes.

However, the Smad2/3-Smad4 heterodimer quite frequently functions in concert with an AP-1 complex to mediate TGFβ-induced transcription. [23] [24] [25] [26] [27] [28] Activation of AP-1 reflects concurrent TGFβ-mediated activation of the mitogen-activated protein (MAP) kinases ERK, JNK and p38. 29 30 Activation of the MAP kinase kinase kinase TAK1 is upstream from JNK and p38 MAP kinase in this signalling pathway. The E3 ubiquitin ligase TRAF6 is capable of binding to kinase-activated TβRI in the TGFβ receptor complex, and this induces the self-ubiquitination (K63) of TRAF6. 31 32 The ubiquitinated TRAF6, in turn, interacts with TAK1 and induces its K63 ubiquitination, activating its MAP kinase activity and thus resulting in downstream activation of JNK and p38 MAP kinase. (This signalling pathway is homologous to TRAF-dependent interleukin (IL)-1-mediated activation of these MAP kinases.)

TGFβ-induced activation of ERK1/2 is mediated by ShcA. 33 TβRI in the activated TGFβ receptor possesses rather weak tyrosine kinase activity; this enables its tyrosine autophosphorylation, inducing binding of ShcA. TβRI then tyrosine phosphorylates ShcA, which can then bind Grb2/Sos to stimulate GTP binding to Ras. Activated Ras, via the canonical Raf-MEK pathway, induces ERK1/2 activation. Activated ERK1/2, JNK and p38 MAP kinase can collaborate to boost c-Fos expression and confer a serine phosphorylation on c-Jun which boosts its transactivational activity. 34 As a result, AP-1 activity is markedly induced, and this collaborates with Smad2/3-Smad4 heterodimers to promote TGFβ-mediated transcription. One of the genes whose transcription is induced in this manner codes for NOX4, which constitutively generates superoxide/hydrogen peroxide. 35 NOX4 induction plays a key role in upregulating TGFβ signalling, as inhibitors of this enzyme notably blunt TGFβ activity. 1 36-38 This is at least partially attributable to the fact that nuclear NOX4 generates hydrogen peroxide which reversibly inhibits MAP kinase phosphatase-1. 39 This latter enzyme functions to deactivate both JNK and p38 MAP kinase; its inactivation by NOX4 hence upregulates JNK and p38 activation, thereby boosting the TGFβ signal. NOX4-mediated inhibition of tyrosine phosphatase activity (such as PTP1B) may also contribute to NOX4's impact on TGFβ signalling. 40 41 CGMP, OESTROGEN RECEPTOR-Β, NRF2, SIRT1 AND HYDROGEN SULFIDE CAN DIMINISH TGFΒ SIGNALLING TGFβ signalling can be opposed by cGMP, the ligandbound oestrogen receptor-β (ERβ), activation of the nrf2 transcription factor and the Sirt1 deacetylase. The effect of cGMP in this regard is mediated by protein kinase G-1a (PKG-1a). This kinase phosphorylates the TGFβ-activated Smad3 (pSmad3) in such a way as to prevent the translocation of pSmad3/Smad4 heterodimers to the nucleus. 42 43 Once phosphorylated by PKG-1a, Smad3 has a high affinity for cytosolic beta2-tubulin, resulting in its sequestration in the cytoplasm. 44 Other research suggests that PKG activity may interfere with TGFβ signalling by promoting the proteasomal degradation of Smad3. 45 Not surprisingly, agents with boost cellular levels of cGMP have also been shown to oppose tissue fibrosis and TGFβ activity. 42 43 46-56 Ligand-bound activated ERβ has been found to downregulate TGFβ-mediated transcription by a direct interaction with AP-1 complexes that blocks their transactivational activity. 57 58 This interaction does not involve binding of ERβ to oestrogen response elements on DNA, but rather to c-Jun. This may rationalise preclinical and epidemiological evidence that endogenous or therapeutic oestrogen provides protection from cardiac hypertrophy, hepatic fibrosis, glomerulosclerosis and primary open-angle glaucoma (POAG). [59] [60] [61] [62] [63] [64] [65] [66] [67] [68] Pertinently, ERβ is expressed in hepatic stellate cells, mesangial cells, cardiac fibroblasts and prostate stroma. 59 62 69-73 Moreover, polymorphisms of the ERβ gene (but not that of the ERα gene) have been linked to increased risk for POAG. 74 75 A number of studies show that activation of the Nrf2 transcription factor, mediator of the phase II response, can suppress TGFβ signalling. [76] [77] [78] [79] [80] [81] Although Nrf2 has the potential to antagonise TGFβ signalling via promotion of glutathione synthesis and various antioxidant enzymesthereby opposing the upregulatory impact of Nox4produced oxidants on TGFβ activity 80 -it also does so by boosting the protein level of SMAD7, which interacts with the type 1 TGFβ receptor in such a way as to block its association with SMAD2/3, and acts in additional ways to oppose SMAD-dependent TGFβ activity. 77 81 82 This effect of Nrf2 is indirect, reflecting its ability to decrease protein expression of SMURF1, an E3 ubiquitin ligase that targets SMAD7 for proteolytic degradation. 77 81 Many studies, though not all, 83 report that increased activity of the class III deacetylase Sirt1 downregulates TGFβ signalling and opposes pathological fibrosis. [84] [85] [86] [87] [88] [89] [90] [91] [92] Conversely, TGFβ activity suppresses Sirt1 expression. 93 The downregulatory effect of Sirt1 on TGFβ signalling is mediated, in part, by decreased protein expression of p300, a histone acetyltransferase which acts as a coactivator for SMAD2/3-dependent transcription; Sirt1 promotes its proteasomal degradation. 85 94 95 However, Sirt1 can deacetylate SMADs 2, 3 and 4, and this may also play a role in this effect. 91 92 Numerous studies have demonstrated that, in vivo, exogenous hydrogen sulfide (H 2 S) inhibits fibrosis in a range of tissues, and, in vitro, opposes TGFβ signalling. [96] [97] [98] [99] [100] [101] [102] [103] [104] [105] [106] [107] [108] [109] That this effect is of physiological significance is suggested by the fact that genetic deficiency of enzymes that generate H 2 S-for example, cystathione-β-synthase (CBS), cystathionine-γ-lyase (CSE)-as well as agents which inhibit expression of these enzymes, promote tissue fibrosis; moreover, expression of these enzymes is often decreased in fibrosis models. 97 100 109-115 In rodent models of fibrosis and in cultured cells exposed to TGFβ, H 2 S suppresses SMAD2/3 phosphorylation and ERK activation. 96 97 101 101 102 116-119 This effect may be partially attributable to decreased expression of TGFβ receptors types I and II, but the possibility that H 2 S intervenes in signalling by the intact receptor cannot be ruled out. 101 119 In vivo, H 2 S has also been reported to decrease TGFβ expression. 101-103 105 NUTRACEUTICALS THAT MAY DOWNREGULATE TGFΒ SIGNALLING These considerations suggest that several nutraceuticals may have potential for downregulating TGFβ activity and thereby opposing pathological fibrosis. In regard to NOX4, it may be possible to decrease its activity via administration of spirulina or of spirulina extracts enriched in phycocyanobilin (PhyCB). The latter, a metabolic derivative and close homolog of biliverdin, has been found to share the latter's ability to inhibit certain nicotinamide adenine dinucleotide phosphate (NADPH) oxidase complexes, including those dependent on NOX4. 120 121 Oxidative stress, via induction of heme oxygenase-1 (HO-1), promotes generation of biliverdin from heme; this biliverdin is rapidly reduced by biliverdin reductase to yield free bilirubin, which in turn quells oxidative stress by inhibiting NADPH oxidase complexes. [122] [123] [124] [125] [126] PhyCB, analogously, is reduced by biliverdin reductase to phycocyanorubin, a homolog of bilirubin that shares its ability to inhibit these complexes. 127 This likely explains, in large part, why oral administration of PhyCB, spirulina or phycocyanin (the spirulina protein which contains PhyCB as a covalently attached chromophore) has exerted profound antioxidant/ anti-inflammatory activity in rodents in a wide variety Editorial of contexts. 120 128 129 In particular, oral administration of spirulina/PhyCB has been shown to inhibit induction of hepatic, pulmonary and oral fibrosis, as well as glomerulosclerosis, in rodent models. 120 130-133 In vitro, exposure of two cancer cell lines to phycocyanin has been shown to inhibit TGFβ-mediated epithelial-mesenchymal transition, blocking induction of type 1 collagen, vimentin, fibronectin and snail, while preserving expression of E-cadherin. 134 Phase II-inducing compounds activate the Nrf2 transcription factor to boost expression of a range of antioxidant enzymes; these include HO-1, which can oppose NADPH oxidase activity by giving rise to intracellular bilirubin via the heme catabolite biliverdin. These agents also oppose or reverse the modulatory impact of hydrogen peroxide on cellular signalling by increasing glutathione synthesis and boosting the expression of a range of antioxidant enzymes. [135] [136] [137] [138] Moreover, they oppose TGFβ signalling by boosting SMAD7 levels. Perhaps the most clinically tested phase II inducer is the physiologically essential cofactor lipoic acid. [139] [140] [141] [142] [143] Indeed, a number of studies have reported that administration of lipoic acid can oppose TGFβ signalling and induction of pathological fibrosis in various rodent models. The utility of lipoic acid in this regard has been reported for fibrosis induced by radiation, bleomycin, laminectomy, abdominal incisions and trabeculectomy; for hepatic fibrosis induced by carbon tetrachloride, thioacetamide and bile duct ligation; and for cardiac fibrosis induced by diabetes. [144] [145] [146] [147] [148] [149] [150] [151] [152] [153] [154] Another natural agent with good clinical potential as a phase II inducer is ferulic acid, a compound widely distributed in plant foods, in free or bound form-and also long employed, as the sodium salt, for cardiovascular protection in Chinese medicine. 155 This agent has likewise shown anti-fibrotic activity in rodent studies. [156] [157] [158] [159] Also clinically useful for phase II induction are broccoli sprout extracts, a rich, bioavailable source of the phase II inducer sulforaphane; these have been shown to exert anti-fibrotic activity in various rodent models. [160] [161] [162] [163] [164] Moreover, in cell culture studies, sulforaphane attenuates TFGβ signalling. 165 166 The neurohormone melatonin, commonly employed as a nutraceutical sleep aid, can upregulate phase II induction by boosting expression of Nrf2 at the transcriptional level. [167] [168] [169] This, in turn, may reflect increased expression of the clock protein transcription factor Bmal1, which drives transcription of the Nrf2 gene. 170 171 However, Bmal1 also induces transcription of the gene coding for Sirt1. 172 Melatonin has been shown to oppose TGFβ activity and fibrosis in rodent studies and cell cultures, and this effect might reflect upregulation of both Nrf2 and Sirt1. [173] [174] [175] [176] [177] [178] Activation of AMP-activated kinase boosts Sirt1 activity in some tissues by increasing expression of nicotinamide ribosyltransferase, rate-limiting for the synthesis of Sirt1's substrate NAD+. 179 180 The phytochemical nutraceutical berberine, which activates AMPK in a matter analogous to the diabetic drug metformin, has been reported to inhibit pulmonary, cardiac, hepatic, pancreatic and renal fibrosis in rodents, likely owing to its upregulatory impact on Sirt1 activity. [181] [182] [183] [184] [185] [186] [187] [188] Its effect in this regard would likely be complementary to that of melatonin.

Although drugs in development or in use which directly activate soluble guanylate cyclase (sGC) and potentiate its responsiveness to nitric oxide have considerable potential for control of fibrotic pathologies, 52 189-192 little consideration has been paid to the fact that, in supraphysiological but well tolerated concentrations (roughly two orders of magnitude over the physiological range), the vitamin biotin can directly activate sGC. [193] [194] [195] The maximum activation which biotin can achieve is twofold to threefold-as opposed to the 100-fold activation which NO can induce-which accounts for the fact that it has been well tolerated clinically in doses as high as 100 mg three times per day. 196 197 (Whether biotin potentiates response to concurrently applied NO, as do sGC activator drugs, has not been reported.) The ability of oral highdose biotin to lower blood pressure and prevent stroke in stroke-prone spontaneously hypertensive rats has been shown to reflect systemic activation of sGC. 198 Favourable clinical effects of high-dose biotin on diabetes control may reflect biotin's impact on sGC. 199 Boosting NO synthesis in tissues threatened by fibrosis could also increase cGMP production. Theoretically, uncoupling of NO synthase in such tissues could upregulate TGFβ signalling. Uncoupling mediated by asymmetric dimethylarginine (ADMA) could be offset with supplemental citrulline, whereas uncoupling reflecting oxidation of NO synthase's cofactor tetrahydrobiopterin might be reversed with high-dose folate supplementation. [200] [201] [202] In this regard, supplemental citrulline is reported to impede progression of diabetic nephropathy in rodents rendered diabetic with streptozotocin, likely reflecting a role for uncoupled endothelial nitric oxide synthase (eNOS) in this syndrome. 203 Indeed, elevated plasma ADMA predicts progression of kidney disease, and likely plays a pathogenic role in this regard. [204] [205] [206] Uncoupling of eNOS is a mediator of diastolic dysfunction in heart failure with preserved ejection fraction; hence, citrulline and/or high-dose folate might aid prevention of cardiac fibrosis in this circumstance. 207 Several studies suggest that peroxynitrite-mediated uncoupling of eNOS may play a pathogenic role in lung and pulmonary artery fibrosis associated with idiopathic pulmonary fibrosis. [208] [209] [210] [211] An elevation of serum ADMA levels has been reported in patients with advanced POAG. 212 Dietary or supplemental nitrates can be converted to NO (after reduction to nitrite by oral bacteria) in tissues, particularly hypoxic tissues. 213 214 Feeding of sodium nitrate or of nitrate-rich beetroot juice to diet-induced obese hypertensive rats has been shown to exert favourable effects on cardiac structure and function, including a reduction in ventricular fibrosis. 215 With respect to ERβ, the multiple health-protective benefits of soy isoflavones have been traced to the fact that, when these agents are ingested in nutritional (as opposed to pharmacological) amounts, the plasma levels of unconjugated genistein and equol that result are sufficient to achieve activation of ERβ, while exerting minimal impact on ERα. [216] [217] [218] [219] [220] For this reason, nutritional intakes of soy isoflavones can evoke the protective effects of ERβ, without the ERα-mediated feminising and pro-carcinogenic effects associated with ERα activation. Hence, soy isoflavone supplementation or a soy-rich diet may have potential for preventing and controlling fibrotic pathologies. Oral administration of genistein suppresses collagen synthesis by rat mesangial cells in vivo, and also inhibits cardiac hypertrophy and fibrosis induced by pressure overload or isoproterenol. [221] [222] [223] Oral soy isoflavones have also provided protection from hepatic fibrosis and radiation-induced pulmonary fibrosis in rodents. [224] [225] [226] [227] A controlled study of soy isoflavone supplementation in watchful-waiting BPH showed only a trend toward benefit, but the daily dose employed (50 mg) likely was suboptimal. 228 However, a clinical evaluation of a synthetic ERβ agonist in BPH likewise had a null outcome; perhaps ERβ agonists would be more effective for prevention than for therapy of this syndrome. 229 Recent studies indicate that the antihypertensive, antiatherosclerotic and brain-protective benefits of taurine administration may in large measure reflect increased expression of enzymes which synthesise H 2 S-namely CBS and CSE. 230 231 This effect has been demonstrated to date in vascular tissues and the brain, but it may well be operative in other tissues. In light of H 2 S's ability to downregulate TGFβ activity cited above, it is notable that taurine has been shown to exert anti-fibrotic effects in a number of rodent models of fibrosis, in a range of tissue, including lungs, liver, heart, kidney, pancreas and penis. [232] [233] [234] [235] [236] [237] [238] [239] [240] [241] [242] [243] [244] Conversely, in mice with a genetic knockout of the taurine transporter, marked cardiac fibrosis is noted. 245 An economical explanation of these findings could be that taurine controls TGFβ activity by supporting endogenous H 2 S generation. In any case, in light of abundant rodent data, inclusion of taurine in nutraceutical regimens intended to oppose pathological fibrosis seems appropriate, particularly as this agent is safe and inexpensive.

Tissue cysteine levels can be rate-limiting for H 2 S synthesis, and those levels tend to decline in the elderly. 246 247 Supplemental N-acetylcysteine (NAC) can also boost tissue levels of the key antioxidant glutathione, which can participate in mechanisms that reverse the pro-inflammatory effects of hydrogen peroxide on signalling pathways. [248] [249] [250] [251] [252] Hence, NAC supplementation has been recommended for the elderly, and might be expected to at least modestly aid control of fibrotic syndromes in this group, both by opposing the pro-fibrotic impact of Nox4-derived hydrogen peroxide, and by enhancing H 2 S synthesis. 247 250 251 Consistent with this speculation, oral administration of NAC has shown favourable effects in multiple rodent models of pathogenic fibrosis. [253] [254] [255] [256] [257] [258] [259] [260] [261] [262] [263] [264] [265] [266] [267] Moreover, NAC also has been shown to downregulate TGFβ signalling in cell cultures. 268 

In summary, spirulina/PhyCB, phase II inducers such as lipoic acid, ferulic acid or broccoli sprout powder, melatonin, berberine, high-dose biotin, soy isoflavones, taurine and NAC may have potential for downregulating TGFβ signalling, and thereby decreasing risk for, or improving clinical control of, a wide range of pro-fibrotic pathologies. Suggested dose schedules for these agents are presented in box 1. With regard to post-COVID-19 syndrome specifically, the antioxidant/anti-inflammatory effects of PhyCB, phase II inducers, melatonin and NAC might address neurological aspects of this syndrome thought likely to reflect chronic inflammation of cerebrovascular endothelial cells and microglia. [269] [270] [271] [272] Further studies are needed to confirm the benefit and safety of this potential nutraceutical strategy in COVID-19.

Contributors All authors contributed to the final manuscript.

Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

Competing interests JJD is Director of Scientific Affairs for Advanced Ingredients for Dietary Products. MM is coinventor and co-owner of US and EU patents pertaining to nutraceutical/pharmaceutical uses of phycocyanobilin oligopeptides extracted from food algae such as spirulina and owns a nutraceutical company. JO is an owner of a nutraceutical company.

Patient consent for publication Not required.

Provenance and peer review Not commissioned; internally peer reviewed.

Open access This is an open access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited, appropriate credit is given, any changes made indicated, and the use is non-commercial. See: http:// creativecommons. org/ licenses/ by-nc/ 4. 0/.

James J DiNicolantonio http:// orcid. org/ 0000-0002-7888-1528 James H O'Keefe http:// orcid. org/ 0000-0002-3376-5822 Box 1 Suggested dose schedules for nutraceuticals with anti-fibrotic potential in COVID-19 and other fibrotic disorders N-acetylcysteine-600 mg two times per day. Lipoic acid-600 mg two times per day. Ferulic acid-250 mg two times per day. Broccoli sprout powder-5 g one to two times per day (providing 20-40 mg of sulforaphane). Spirulina-15 g one time per day. Melatonin-10 mg at bedtime. Berberine-500 mg two times per day. Taurine-1 g two times per day. Folate-10 mg two times per day. Soy Isoflavones-75 mg two times per day. Biotin-10 mg two times per day. Vitamin D-4000 IU daily.

Ros signaling by Nox4 drives fibroblast-to-myofibroblast differentiation in the diseased prostatic stroma

Increased expression of genes for basic fibroblast growth factor and transforming growth factor type beta 2 in human benign prostatic hyperplasia

Aberrant transforming growth factor-β activation recruits mesenchymal stem cells during prostatic hyperplasia

A role for epithelial-mesenchymal transition in the etiology of benign prostatic hyperplasia

Transforming growth factor-β signaling through the Smad proteins: role in systemic sclerosis

Autocrine TGF-beta signaling in the pathogenesis of systemic sclerosis

Transforming growth factor-beta in systemic sclerosis (scleroderma)

Role of integrin-mediated TGFβ activation in the pathogenesis of pulmonary fibrosis

Recent advances in molecular targets and treatment of idiopathic pulmonary fibrosis: focus on TGFbeta signaling and the myofibroblast

Transforming growth factor-and the progression of renal disease

Role of TGF-β in chronic kidney disease: an integration of tubular, glomerular and vascular effects

Molecular pathogenesis of liver fibrosis

Therapeutic strategies against TGF-β signaling pathway in hepatic fibrosis

Induction of cardiac fibrosis by transforming growth factor-β1

Role of transforming growth factor-β in the progression of heart failure

Molecular mechanisms that control interstitial fibrosis in the pressure-overloaded heart

Primary open-angle glaucoma: a transforming growth factor-beta pathway-mediated disease

Pro-Fibrotic pathway activation in trabecular meshwork and lamina cribrosa is the main driving force of glaucoma

Peyronie's disease is associated with an increase in transforming growth factor-beta protein expression

Alterations in the transforming growth factor (TGF)-beta pathway as a potential factor in the pathogenesis of Peyronie's disease

Discharge may not be the end of treatment: pay attention to pulmonary fibrosis caused by severe COVID-19

Post COVID-19 fibrosis, an emerging complicationof SARS-CoV-2 infection

Smad3 and Smad4 cooperate with c-Jun/c-Fos to mediate TGF-β-induced transcription

Smad3/AP-1 interactions control transcriptional responses to TGF-β in a promoter-specific manner

Functional cooperation between Smad proteins and activator protein-1 regulates transforming growth factor-beta-mediated induction of endothelin-1 expression

Induction of human LTBP-3 promoter activity by TGF-β1 is mediated by Smad3/4 and AP-1 binding elements

Smads bind directly to the Jun family of AP-1 transcription factors

Efficient TGF-beta induction of the Smad7 gene requires cooperation between AP-1, Sp1, and Smad proteins on the mouse Smad7 promoter

Non-Smad signaling pathways

MAPK/AP-1-dependent regulation of PAI-1 gene expression by TGF-beta in rat mesangial cells

Traf6 mediates Smadindependent activation of JNK and p38 by TGF-beta

The type I TGF-β receptor engages TRAF6 to activate TAK1 in a receptor kinase-independent manner

TGF-β activates ERK MAP kinase signalling through direct phosphorylation of ShcA

The regulation of AP-1 activity by mitogen-activated protein kinases

A far-upstream AP-1/Smad binding box regulates human Nox4 promoter activation by transforming growth factor-β

Nox4 modulates collagen production stimulated by transforming growth factor β1 in vivo and in vitro

Nadph oxidase-dependent redox signaling in TGF-β-mediated fibrotic responses

Therapeutic targeting of redox signaling in myofibroblast differentiation and age-related fibrotic disease

Oxidative modification of nuclear mitogen-activated protein kinase phosphatase 1 is involved in transforming growth factor beta1-induced expression of plasminogen activator inhibitor 1 in fibroblasts

Nox4-derived ROS signaling contributes to TGF-beta-induced epithelial-mesenchymal transition in pancreatic cancer cells

Nox4 and redox signaling mediate TGFbeta-induced endothelial cell apoptosis and phenotypic switch

Anp signaling inhibits TGF-β-induced Smad2 and Smad3 nuclear translocation and extracellular matrix expression in rat pulmonary arterial smooth muscle cells

Atrial natriuretic peptide inhibits transforming growth factor β-induced Smad signaling and myofibroblast transformation in mouse cardiac fibroblasts

cGMP inhibits TGF-beta signaling by sequestering Smad3 with cytosolic beta2-tubulin in pulmonary artery smooth muscle cells

Nitric oxide regulates transforming growth factor-β signaling in endothelial cells

Phosphodiesterase-5 inhibition by sildenafil citrate in a rat model of bleomycin-induced lung fibrosis

Increased cardiac myocyte PDE5 levels in human and murine pressure overload hypertrophy contribute to adverse LV remodeling

Roles of cGMPdependent protein kinase I (cGKI) and PDE5 in the regulation of Ang II-induced cardiac hypertrophy and fibrosis

Sildenafil attenuates the fibrotic phenotype of skin fibroblasts in patients with systemic sclerosis

Activators and stimulators of soluble guanylate cyclase counteract myofibroblast differentiation of prostatic and dermal stromal cells

The soluble guanylate cyclase activator cinaciguat prevents cardiac dysfunction in a rat model of type-1 diabetes mellitus

The potential of sGC modulators for the treatment of age-related fibrosis: a mini-review

Inhibition of the TGFβ signalling pathway by cGMP and cGMP-dependent kinase I in renal fibrosis

Effect of atrial natriuretic peptide on left ventricular remodelling in patients with acute myocardial infarction

Natriuretic peptide/ natriuretic peptide receptor-A (NPR-A) system has inhibitory effects in renal fibrosis in mice

Targeted disruption of guanylyl cyclase-A/natriuretic peptide receptor-A gene provokes renal fibrosis and remodeling in null mutant mice: role of proinflammatory cytokines

Estrogen receptors inhibit Smad3 transcriptional activity through AP-1 transcription factors

Differential ligand activation of estrogen receptors ERalpha and ERbeta at AP1 sites

Estrogen receptor beta signals to inhibition of cardiac fibrosis

Rescue of pressure overloadinduced heart failure by estrogen therapy

Cardiomyocyte-Specific overexpression of oestrogen receptor β improves survival and cardiac function after myocardial infarction in female and male mice

Estrogen receptor-β prevents cardiac fibrosis

Female sex and estrogen receptor-β attenuate cardiac remodeling and apoptosis in pressure overload

Gender and the prevalence and progression of renal disease

Estrogen receptor-β mediates male-female differences in the development of pressure overload hypertrophy

Impact of oestrogens on the progression of liver disease

Estrogen reduces CCl4-induced liver fibrosis in rats

Is estrogen a therapeutic target for glaucoma?

Hepatic stellate cells contain the functional estrogen receptor β but not the estrogen receptor α in male and female rats

Expression and regulation of estrogen receptors in mesangial cells: influence on matrix metalloproteinase-9

Decreased expression of stromal estrogen receptor α and β in prostate cancer

Oestrogen and benign prostatic hyperplasia: effects on stromal cell proliferation and local formation from androgen

Zone-dependent expression of estrogen receptors α and β in human benign prostatic hyperplasia

Estrogen receptor beta gene polymorphism and intraocular pressure elevation in female patients with primary open-angle glaucoma

Estrogen receptors alpha and beta and the risk of open-angle glaucoma: the Rotterdam study

Sulforaphane attenuates hepatic fibrosis via NF-E2-related factor 2-mediated inhibition of transforming growth factor-β/SMAD signaling

Inhibitory role of the Keap1-Nrf2 pathway in TGFβ1-stimulated renal epithelial transition to fibroblastic cells: a modulatory effect on Smad signaling

Epigallocatechin-3-Gallate attenuates transforming growth factor-β1 induced epithelial-mesenchymal transition via Nrf2 regulation in renal tubular epithelial cells

Sulforaphane mitigates muscle fibrosis in mdx mice via Nrf2-mediated inhibition of TGF-β/Smad signaling

Nf-E2-Related factor 2 suppresses intestinal fibrosis by inhibiting reactive oxygen species-dependent TGF-β1/SMADs pathway

Bardoxolone ameliorates TGF-β1-associated renal fibrosis through Nrf2/Smad7 elevation

Regulation of TGF-beta signaling by Smad7

Sirt1 regulates canonical TGF-β signalling to control fibroblast activation and tissue fibrosis

Sirt1 activation ameliorates renal fibrosis by inhibiting the TGF-β/Smad3 pathway

The histone deacetylase sirtuin 1 is reduced in systemic sclerosis and abrogates fibrotic responses by targeting transforming growth factor β signaling

Sirt1 activation attenuates diastolic dysfunction by reducing cardiac fibrosis in a model of anthracycline cardiomyopathy

Sirtuin 1 activation reduces transforming growth factor-β1-induced fibrogenesis and affords organ protection in a model of progressive, experimental kidney and associated cardiac disease

Sirtuin1 protects against systemic sclerosis-related pulmonary fibrosis by decreasing proinflammatory and profibrotic processes

High glucose up-regulates microRNA-34a-5p to aggravate fibrosis by targeting SIRT1 in HK-2 cells

Sirt1 interaction with active Smad2 modulates transforming growth factor-β regulated transcription

Sirt1 inhibits TGF-β-induced endothelialmesenchymal transition in human endothelial cells with Smad4 deacetylation

Sirtuin 1 activation attenuates cardiac fibrosis in a rodent pressure overload model by modifying Smad2/3 transactivation

Upregulation of long non-coding RNA HIF 1α-anti-sense 1 induced by transforming growth factor-β-mediated targeting of sirtuin 1 promotes osteoblastic differentiation of human bone marrow stromal cells

Activation and overexpression of SIRT1 attenuates lung fibrosis via p300

Resveratrol improves cardiomyopathy in dystrophin-deficient mice through SIRT1 protein-mediated modulation of p300 protein

Hydrogen sulfide attenuates paraquat-induced epithelial-mesenchymal transition of human alveolar epithelial cells through regulating transforming growth factor-β1/Smad2/3 signaling pathway

Hydrogen sulfide attenuates epithelial-mesenchymal transition of human alveolar epithelial cells

Rescue of mesangial cells from high glucose-induced over-proliferation and extracellular matrix secretion by hydrogen sulfide

Hydrogen sulfide inhibits the renal fibrosis of obstructive nephropathy

Hydrogen sulfide alleviates myocardial collagen remodeling in association with inhibition of TGF-β/Smad signaling pathway in spontaneously hypertensive rats

Hydrogen sulfide donor GYY4137 protects against myocardial fibrosis

Hydrogen sulfide suppresses transforming growth factor-β1-induced differentiation of human cardiac fibroblasts into myofibroblasts

Hydrogen sulfide inhibits transforming growth factor beta-1 induced bronchial epithelialmesenchymal transition

H 2 S improves renal fibrosis in STZinduced diabetic rats by ameliorating TGF-β1 expression

Is hydrogen sulfide a potential novel therapy to prevent renal damage during ureteral obstruction?

Hydrogen sulfide attenuates myocardial fibrosis in diabetic rats through the JAK/STAT signaling pathway

Reversal of Sp1 transactivation and TGFβ1/SMAD1 signaling by H 2 S prevent nickel-induced fibroblast activation

Hydrogen sulfide as a potential therapeutic target in fibrosis

Cystathionine β synthase deficiency promotes oxidative stress, fibrosis, and steatosis in mice liver

Mice lacking cystathionine beta synthase have lung fibrosis and air space enlargement

Loss of the protein cystathionine β-synthase during kidney injury promotes renal tubulointerstitial fibrosis

Cystathionine γ-Lyase Deficiency Exacerbates CCl 4 -Induced Acute Hepatitis and Fibrosis in the Mouse Liver

Hydrogen sulfide-producing cystathionine γ-lyase is critical in the progression of kidney fibrosis

Hydrogen sulfide attenuates the pathogenesis of pulmonary fibrosis induced by bleomycin in rats

The protective effect of hydrogen sulfide on systemic sclerosis associated skin and lung fibrosis in mice model

Involvement of hydrogen sulfide and homocysteine transsulfuration pathway in the progression of kidney fibrosis after ureteral obstruction

Hydrogen sulfide inhibits epithelialmesenchymal transition in peritoneal mesothelial cells

Exogenous H2S mitigates myocardial fibrosis in diabetic rats through suppression of the canonical Wnt pathway

Clinical potential of Spirulina as a source of phycocyanobilin

Phycocyanin and phycocyanobilin from Spirulina platensis protect against diabetic nephropathy by inhibiting oxidative stress

Bilirubin decreases nos2 expression via inhibition of NAD(P)H oxidase: implications for protection against endotoxic shock in rats

Carbon monoxide and bilirubin from heme oxygenase-1 suppresses reactive oxygen species generation and plasminogen activator inhibitor-1 induction

NO modulates NADPH oxidase function via heme oxygenase-1 in human endothelial cells

Induction of heme oxygenase-1 in vivo suppresses NADPH Oxidase-Derived oxidative stress

Nox4 NADPH oxidase mediates oxidative stress and apoptosis caused by TNF-alpha in cerebral vascular endothelial cells

Inactivation of phytochromeand phycobiliprotein-chromophore precursors by rat liver biliverdin reductase

Rimbau V. C-phycocyanin: a biliprotein with antioxidant, anti-inflammatory and neuroprotective effects

Medical application of Spirulina platensis derived C-phycocyanin

Anti-oxidative and antiinflammatory effects of Spirulina on rat model of non-alcoholic steatohepatitis

Efficacy of Spirulina as an antioxidant adjuvant to corticosteroid injection in management of oral submucous fibrosis

C-Phycocyanin suppresses transforming growth factor-β1-induced epithelial mesenchymal transition in human epithelial cells

The glutathione peroxidases. CMLS

Glutathione in defense and signaling: lessons from a small thiol

Glutaredoxin: role in reversible protein s-glutathionylation and regulation of redox signal transduction and protein translocation

Thiol-dependent recovery of catalytic activity from oxidized protein tyrosine phosphatases

Decline in transcriptional activity of Nrf2 causes age-related loss of glutathione synthesis, which is reversible with lipoic acid

Alpha-lipoic acidinduced heme oxygenase-1 expression is mediated by nuclear factor erythroid 2-related factor 2 and p38 mitogen-activated protein kinase in human monocytic cells

Alpha-lipoic acid as a dietary supplement: molecular mechanisms and therapeutic potential

Sulforaphane and α-lipoic acid upregulate the expression of the π class of glutathione S-transferase through c-Jun and Nrf2 activation

Cap-independent Nrf2 translation is part of a lipoic acid-stimulated detoxification stress response

Therapeutic effects of alphalipoic acid on bleomycin-induced pulmonary fibrosis in rats

Alpha-lipoic acid inhibits hepatic PAI-1 expression and fibrosis by inhibiting the TGF-β signaling pathway

Alpha-lipoic acid inhibits liver fibrosis through the attenuation of ROS-triggered signaling in hepatic stellate cells activated by PDGF and TGF-β

The effect of alpha-lipoic acid in the prevention of peritoneal adhesions

Protective effects of curcumin, α-lipoic acid, and N-acetylcysteine against carbon tetrachloride-induced liver fibrosis in rats

Alpha-lipoic acid reduces peridural fibrosis after laminectomy of lumbar vertebrae in rabbits

Cardiac fibrosis and dysfunction in experimental diabetic cardiomyopathy are ameliorated by alphalipoic acid

Alpha-Lipoic acid attenuates cardiac fibrosis in Otsuka Long-Evans Tokushima fatty rats

Reduction of conjunctival fibrosis after trabeculectomy using topical alpha-lipoic acid in rabbit eyes

Alpha-Lipoic acid inhibits peridural fibrosis following laminectomy through the inactivation of TGF-beta1, PDGF, PAI-1 and IL-6 expressions

Effects of alpha lipoic acid on intra-abdominal adhesion: an experimental study in a rat model

Ferulic acid may target MyD88-mediated pro-inflammatory signaling -implications for the health protection afforded by whole grains, anthocyanins, and coffee

Ferulic acid attenuates liver fibrosis and hepatic stellate cell activation via inhibition of TGF-β/Smad signaling pathway

Sichuan Da Xue Xue Bao Yi Xue Ban

Ferulic Acid Attenuates TGF-β 1-Induced Renal Cellular Fibrosis in NRK-52E Cells by Inhibiting Smad/ILK/Snail Pathway

Ferulic acid suppresses activation of hepatic stellate cells through ERK1/2 and Smad signaling pathways in vitro

Broccoli sprouts: an exceptionally rich source of inducers of enzymes that protect against chemical carcinogens

Sulforaphane bioavailability from Glucoraphanin-Rich broccoli: control by active endogenous myrosinase

Potential efficacy of broccoli sprouts as a unique supplement for management of type 2 diabetes and its complications

Sulforaphane prevents the development of cardiomyopathy in type 2 diabetic mice probably by reversing oxidative stress-induced inhibition of Lkb1/AMPK pathway

Broccoli sprout extract prevents diabetic cardiomyopathy via Nrf2 activation in db/db T2DM mice

Effects of the isothiocyanate sulforaphane on TGF-β1-induced rat cardiac fibroblast activation and extracellular matrix interactions

Sulforaphane attenuates pulmonary fibrosis by inhibiting the epithelial-mesenchymal transition

Melatonin ameliorates cerulein-induced pancreatitis by the modulation of nuclear erythroid 2-related factor 2 and nuclear factor-kappaB in rats

Effect of melatonin on the expression of Nrf2 and NF-κB during cyclophosphamide-induced urinary bladder injury in rat

Melatonin prevents the decreased activity of antioxidant enzymes and activates nuclear erythroid 2-related factor 2 signaling in an animal model of fulminant hepatic failure of viral origin

Disruption of the NF-κB/ NLRP3 connection by melatonin requires retinoid-related orphan receptor-α and blocks the septic response in mice

Circadian clock protein BMAL1 regulates IL-1β in macrophages via Nrf2

CLOCK/BMAL1 regulates circadian change of mouse hepatic insulin sensitivity by SIRT1

Preventive effect of melatonin on bleomycin-induced lung fibrosis in rats

The effect of melatonin on bleomycin-induced pulmonary fibrosis in rats

Melatonin: the dawning of a treatment for fibrosis?

Melatonin protects against lung fibrosis by regulating the Hippo/YAP pathway

Idiopathic pulmonary fibrosis (IPF) signaling pathways and protective roles of melatonin

Melatonin suppresses fibrotic responses induced by cigarette smoke via downregulation of TGF-β1

Glucose restriction inhibits skeletal myoblast differentiation by activating SIRT1 through AMPKmediated regulation of NAMPT

Skeletal muscle NAMPT is induced by exercise in humans

Berberine, a natural plant product, activates AMP-activated protein kinase with beneficial metabolic effects in diabetic and insulin-resistant states

Berberine attenuates bleomycin induced pulmonary toxicity and fibrosis via suppressing NF-κB dependant TGF-β activation: a biphasic experimental study

Berberine ameliorates renal interstitial fibrosis induced by unilateral ureteral obstruction in rats

Protective effect of berberine on renal fibrosis caused by diabetic nephropathy

Antioxidant and antiinflammatory activities of berberine attenuate hepatic fibrosis induced by thioacetamide injection in rats

Protective role of berberine in isoprenaline-induced cardiac fibrosis in rats

Berberine attenuates severity of chronic pancreatitis and fibrosis via AMPK-mediated inhibition of TGF-β1/Smad signaling and M2 polarization

Stimulators of soluble guanylate cyclase (sGC) inhibit experimental skin fibrosis of different aetiologies

Activators and stimulators of soluble guanylate cyclase counteract myofibroblast differentiation of prostatic and dermal stromal cells

The soluble guanylate cyclase activator cinaciguat prevents cardiac dysfunction in a rat model of type-1 diabetes mellitus

Inhibition of the TGFβ signalling pathway by cGMP and cGMP-dependent kinase I in renal fibrosis

Biotin enhances guanylate cyclase activity

Stimulation of guanylate cyclase and RNA polymerase II activities in HeLa cells and fibroblasts by biotin

Biotin increases glucokinase expression via soluble guanylate cyclase/ protein kinase G, adenosine triphosphate production and autocrine action of insulin in pancreatic rat islets☆

Present knowledge in nutrition

MD1003 (high-dose biotin) for the treatment of progressive multiple sclerosis: a randomised, double-blind, placebo-controlled study

Antihypertensive effect of biotin in stroke-prone spontaneously hypertensive rats

High-Dose biotin, an inducer of glucokinase expression, may synergize with chromium picolinate to enable a definitive nutritional therapy for type II diabetes

Asymmetric dimethylarginine is a well established mediating risk factor for cardiovascular morbidity and Mortality-Should patients with elevated levels be supplemented with citrulline?

Recoupling of eNOS with folic acid prevents abdominal aortic aneurysm formation in angiotensin IIinfused apolipoprotein E null mice

Folic acid promotes recycling of tetrahydrobiopterin and protects against hypoxiainduced pulmonary hypertension by Recoupling endothelial nitric oxide synthase

L-Citrulline protects from kidney damage in type 1 diabetic mice

Role of asymmetrical dimethylarginine in the progression of renal disease

Asymmetric dimethylarginine (ADMA) induces chronic kidney disease through a mechanism involving collagen and TGF-β1 synthesis

Involvement of asymmetric dimethylarginine (ADMA) in glomerular capillary loss and sclerosis in a rat model of chronic kidney disease (CKD)

Uncoupled cardiac nitric oxide synthase mediates diastolic dysfunction

Increased production of the potent oxidant peroxynitrite in the lungs of patients with idiopathic pulmonary fibrosis

Nitric oxide attenuates epithelial-mesenchymal transition in alveolar epithelial cells

Role of tetrahydrobiopterin in pulmonary vascular remodelling associated with pulmonary fibrosis

Elevated asymmetric dimethylarginine alters lung function and induces collagen deposition in mice

Elevation of serum asymmetrical and symmetrical dimethylarginine in patients with advanced glaucoma

Roles of dietary inorganic nitrate in cardiovascular health and disease

Inorganic nitrate: a major player in the cardiovascular health benefits of vegetables

Beetroot and sodium nitrate ameliorate cardiometabolic changes in Diet-Induced obese hypertensive rats

Comparison of the ligand binding specificity and transcript tissue distribution of estrogen receptors alpha and beta

Interaction of Estrogenic chemicals and phytoestrogens with estrogen receptor β

Isoflavones made simple -Genistein's agonist activity for the beta-type estrogen receptor mediates their health benefits

Mechanisms enforcing the estrogen receptor β selectivity of botanical estrogens

Emerging evidence of the health benefits of S-equol, an estrogen receptor β agonist

Selective estrogen receptor modulators suppress mesangial cell collagen synthesis

Genistein alleviates pressure overloadinduced cardiac dysfunction and interstitial fibrosis in mice

Genistein prevents isoproterenol-induced cardiac hypertrophy in rats

Dietary supplementation of genistein alleviates liver inflammation and fibrosis mediated by a methionine-choline-deficient diet in db/db mice

Soy isoflavone delays the progression of thioacetamide-induced liver fibrosis in rats

Genistein attenuates D-GalN induced liver fibrosis/chronic liver damage in rats by blocking the TGF-β/Smad signaling pathways

Radioprotection of lung tissue by soy isoflavones

Isoflavones in treating watchful waiting benign prostate hyperplasia: a double-blinded, randomized controlled trial

Estrogen receptor beta agonist LY500307 fails to improve symptoms in men with enlarged prostate secondary to benign prostatic hypertrophy

Taurine supplementation lowers blood pressure and improves vascular function in prehypertension: randomized, double-blind, placebo-controlled study

Taurine supplementation reduces neuroinflammation and protects against white matter injury after intracerebral hemorrhage in rats

The combined treatment with taurine and niacin blocks the bleomycin-induced activation of nuclear factor-kappaB and lung fibrosis

Protective effect of taurine against renal interstitial fibrosis of rats induced by cisplatin

Taurine inhibits oxidative damage and prevents fibrosis in carbon tetrachloride-induced hepatic fibrosis

Transforming growth factor-?-induced stimulation of formation of collagen fiber network and anti-fibrotic effect of taurine in an in vitro model of hepatic fibrosis

Betaine or taurine administration prevents fibrosis and lipid peroxidation induced by rat liver by ethanol plus carbon tetrachloride intoxication

Protection of bleomycin-induced fibrosis and inflammation by taurine

Taurine enhances the metabolism and detoxification of ethanol and prevents hepatic fibrosis in rats treated with iron and alcohol

Oral administration of taurine improves experimental pancreatic fibrosis

Taurine: a potential novel addition to the anti-systemic sclerosis weaponry

Taurine attenuates radiation-induced lung fibrosis in C57/Bl6 fibrosis prone mice

Effect of taurine on acinar cell apoptosis and pancreatic fibrosis in dibutyltin dichlorideinduced chronic pancreatitis

Taurine drinking ameliorates hepatic granuloma and fibrosis in mice infected with Schistosoma japonicum

Taurine supplementation improves erectile function in rats with streptozotocin-induced type 1 diabetes via amelioration of penile fibrosis and endothelial dysfunction

Tissue taurine depletion induces profibrotic pattern of gene expression and causes aging-related cardiac fibrosis in heart in mice

Boosting endogenous production of vasoprotective hydrogen sulfide via supplementation with taurine and N-acetylcysteine: a novel way to promote cardiovascular health

The deficit in low molecular weight thiols as a target for antiageing therapy

N-Acetylcysteine-a safe antidote for cysteine/glutathione deficiency

N -acetylcysteine for antioxidant therapy: pharmacology and clinical utility

An increased need for dietary cysteine in support of glutathione synthesis may underlie the increased risk for mortality associated with low protein intake in the elderly

Deficient synthesis of glutathione underlies oxidative stress in aging and can be corrected

by dietary cysteine and glycine supplementation

Glutathione in defense and signaling: lessons from a small thiol

Oral N-acetylcysteine reduces bleomycin-induced collagen deposition in the lungs of mice

Attenuation of bleomycin-induced lung injury and oxidative stress by Nacetylcysteine plus deferoxamine

N -acetylcysteine attenuates subcutaneous administration of bleomycin-induced skin fibrosis and oxidative stress in a mouse model of scleroderma

N-Acetyl cysteine improves the diabetic cardiac function: possible role of fibrosis inhibition

N-Acetylcysteine alleviates angiotensin II-mediated renal fibrosis in mouse obstructed kidneys

N-acetylcysteine attenuates the development of cardiac fibrosis and remodeling in a mouse model of heart failure

N-Acetyl cysteine: a possible treatment for diabetic cardiomyopathy

N-Acetylcysteine Attenuates the Development of Renal Fibrosis in Transgenic Mice with Dilated Cardiomyopathy

N-Acetylcysteine tiherapeutically protects against pulmonary fibrosis in a mouse model of silicosis

Attenuation by oral Nacetylcysteine of bleomycin-induced lung injury in rats

Role of Nacetylcysteine on fibrosis and oxidative stress in cirrhotic rats

N-Acetylcysteine prevents carbon tetrachloride-induced liver cirrhosis: role of liver transforming growth factor-beta and oxidative stress

Could N -acetylcysteine slow progression of idiopathic pulmonary fibrosis by inhibiting EMT?

Antifibrotic and antioxidant effects of N-acetylcysteine in an experimental cholestatic model

High-Dose N-acetylcysteine decreases silica-induced lung fibrosis in the rat

N-Acetyl-L-Cysteine suppresses TGF-β signaling at distinct molecular steps: the biochemical and biological efficacy of a multifunctional, antifibrotic drug

The potential role of inflammation reaction in COVID-19 related posttraumatic stress disorder

Neuropathobiology of COVID-19: the role for glia

Would repurposing minocycline alleviate neurologic manifestations of COVID-19?

Neurological infection with SARS-CoV-2 -the story so far