GKT137831

Ki: 140 nM and 110 nM

GKT137831 is a specific dual NADPH oxidase Nox1/Nox4 inhibitor, respectively[1].

Both Nox1 and Nox4 expressed in vascular smooth muscle cells (VSMCs) are targeted to discreet intracellular locations, are differentially regulated in response to growth factors and vascular injury, and are activated by distinct mechanis

In vitro: GKT137831 lowers hypoxia-induced H(2)O(2) release, cell proliferation, and TGF-β1 expression and attenuated reductions in PPARγ in HPAECs and HPASMCs. [2] GKT137831 also is a blockade of oxidative stress in response to hyperglycemia in human aortic endothelial cells. [3]

In vivo: In WT and SOD1mut mice, GKT137831 (60 mg/kg i.g.) prevents liver fibrosis and downregulates markers of oxidative stress, inflammation, and fibrosis. [1] In mouse model of chronic hypoxia exposure, GKT137831 (60 mg/kg/d p.o.) attenuates lung PPARγ and TGF-β1 expression of chronic hypoxia–induced right ventricular hypertrophy, vascular remodeling, lung cell proliferation, and hypoxic alterations [2]. GKT137831 (60 mg/kg/d p.o.) also attenuates diabetes mellitus-stimulated atherosclerosis in diabetic apolipoprotein E-deficient mice. [3] Furtermore, GKT137831 prevents the increase of oxidative stress in angII-infused c-hNox4Tg mice, abolishes Akt-mTOR and NF-κB signaling pathway and lowers cardiac remodeling. [4]

Clinical trial: Clinical study has been conducted.

References:
[1] Aoyama T, Paik YH, Watanabe S, Laleu B, Gaggini F, Fioraso-Cartier L, Molango S, Heitz F, Merlot C, Szyndralewiez C, Page P, Brenner DA.  Nicotinamide adenine dinucleotide phosphate oxidase in experimental liver fibrosis: GKT137831 as a novel potential therapeutic agent. Hepatology. 2012 Dec;56(6):2316-27.
[2] Green DE, Murphy TC, Kang BY, Kleinhenz JM, Szyndralewiez C, Page P, Sutliff RL, Hart CM.  Circulation. The Nox4 inhibitor GKT137831 attenuates hypoxia-induced pulmonary vascular cell proliferation. Am J Respir Cell Mol Biol. 2012 Nov;47(5):718-26.
[3] Gray SP, Di Marco E, Okabe J, Szyndralewiez C, Heitz F, Montezano AC, de Haan JB, Koulis C, El-Osta A, Andrews KL, Chin-Dusting JP, Touyz RM, Wingler K, Cooper ME, Schmidt HH, Jandeleit-Dahm KA.  NADPH oxidase 1 plays a key role in diabetes mellitus-accelerated atherosclerosis. Circulation. 2013 May 7;127(18):1888-902.
[4] Zhao QD, Viswanadhapalli S2, Williams P2, Shi Q2, Tan C2, Yi X2, Bhandari B2, Abboud HE2.  NADPH oxidase 4 induces cardiac fibrosis and hypertrophy through activating Akt/mTOR and NFκB signaling pathways. Circulation. 2015 Feb 17;131(7):643-55.

Inhibition of NOX1/4 with GKT137831: a potential novel treatment to attenuate neuroglial cell inflammation in the retina.[Pubmed:26219952]

J Neuroinflammation. 2015 Jul 30;12:136.

BACKGROUND: Inflammation and the excess production of reactive oxygen species (ROS) contribute significantly to the pathogenesis of ischemic retinopathies such as diabetic retinopathy and retinopathy of prematurity. We hypothesized that GKT137831, a dual inhibitor of NADPH oxidases (NOX) 1 and NOX4, reduces inflammation in the ischemic retina by dampening the pro-inflammatory phenotype of retinal immune cells as well as macroglial Muller cells and neurons. METHODS: Ischemic retinopathy was induced in Sprague-Dawley rats by exposure to 80 % O2 cycled with 21 % O2 for 3 h per day from postnatal day (P) 0 to P11, followed by room air (P12 to P18). GKT137831 was administered P12 to P18 (60 mg/kg, subcutaneous) and comparisons were to room air controls. Retinal inflammation was examined by measuring leukocyte adherence to the retinal vasculature, ionized calcium-binding adaptor protein-1-positive microglia/macrophages, and the mRNA and protein levels of key inflammatory factors involved in retinal disease. Damage to Muller cells was evaluated by quantitating glial fibrillary acidic protein-positive cells and vascular leakage with an albumin ELISA. To verify the anti-inflammatory actions of GKT137831 on glia and neurons involved in ischemic retinopathy, primary cultures of rat retinal microglia, Muller cells, and ganglion cells were exposed to the in vitro counterpart of ischemia, hypoxia (0.5 %), and treated with GKT137831 for up to 72 h. ROS levels were evaluated with dihydroethidium and the protein and gene expression of inflammatory factors with quantitative PCR, ELISA, and a protein cytokine array. RESULTS: In the ischemic retina, GKT137831 reduced the increased leukocyte adherence to the vasculature, the pro-inflammatory phenotype of microglia and macroglia, the increased gene and protein expression of vascular endothelial growth factor, monocyte chemoattractant protein-1, and leukocyte adhesion molecules as well as vascular leakage. In all cultured cell types, GKT137831 reduced the hypoxia-induced increase in ROS levels and protein expression of various inflammatory mediators. CONCLUSIONS: NOX1/4 enzyme inhibition with GKT137831 has potent anti-inflammatory effects in the retina, indicating its potential as a treatment for a variety of vision-threatening retinopathies.

Early oxidative damage induced by doxorubicin: Source of production, protection by GKT137831 and effect on Ca(2+) transporters in HL-1 cardiomyocytes.[Pubmed:26906075]

Arch Biochem Biophys. 2016 Mar 15;594:26-36.

In atrial-derived HL-1 cells, ryanodine receptor and Na(+)/Ca(2+)-exchanger were altered early by 5 muM doxorubicin. The observed effects were an increase of cytosolic Ca(2+) at rest, ensuing ryanodine receptor phosphorylation, and the slowing of Ca(2+) transient decay after caffeine addition. Doxorubicin triggered a linear rise of reactive oxygen species (ROS) with no early effect on mitochondrial inner membrane potential. Doxorubicin and ROS were both detected in mitochondria by colocalization with fluorescence probes and doxorubicin-induced ROS was totally blocked by mitoTEMPO. The NADPH oxidase activity in the mitochondrial fraction was sensitive to inhibition by GKT137831, and doxorubicin-induced ROS decreased gradually as the GKT137831 concentration added in preincubation was increased. When doxorubicin-induced ROS was prevented by GKT137831, the kinetic response revealed a permanent degree of protection that was consistent with mitochondrial NADPH oxidase inhibition. In contrast, the ROS induction by doxorubicin after melatonin preincubation was totally eliminated at first but the effect was completely reversed with time. Limiting the source of ROS production is a better alternative for dealing with oxidative damage than using ROS scavengers. The short-term effect of doxorubicin on Ca(2+) transporters involved in myocardiac contractility was dependent on oxidative damage, and so the impairment was subsequent to ROS production.

Combined NOX1/4 inhibition with GKT137831 in mice provides dose-dependent reno- and atheroprotection even in established micro- and macrovascular disease.[Pubmed:28160092]

Diabetologia. 2017 May;60(5):927-937.

AIMS/HYPOTHESIS: Oxidative stress is a promising target in diabetes-associated vasculopathies, with inhibitors of NADPH oxidases (NOX), in particular isoforms 1 and 4, shown to be safe in early clinical development. We have explored a highly relevant late-stage intervention protocol using the clinically most advanced compound, the NOX1/4 inhibitor GKT137831, to determine whether end-organ damage can be reversed/attenuated when GKT137831 is administered in the setting of established diabetic complications. METHODS: GKT137831 was administered at two doses, 30 mg kg(-1) day(-1) and 60 mg kg(-1) day(-1), to ApoE (-/-) mice 10 weeks after diabetes induction with streptozotocin (STZ), for a period of 10 weeks. RESULTS: Consistent with Nox4 (-/-) mouse data, GKT137831 was protective in a model of diabetic nephropathy at both the 30 mg kg(-1) day(-1) and 60 mg kg(-1) day(-1) doses, through suppression of proinflammatory and profibrotic processes. Conversely, in diabetic atherosclerosis, where Nox1 (-/y) and Nox4 (-/-) mice have yielded qualitatively opposing results, the net effect of pharmacological NOX1/4 inhibition was protection, albeit to a lower extent and only at the lower 30 mg kg(-1) day(-1) dose. CONCLUSIONS/INTERPRETATION: As dose-dependent and tissue-specific effects of the dual NOX1/4 inhibitor GKT137831 were observed, it is critical to define in further studies the relative balance of inhibiting NOX4 vs NOX1 in the micro- and macrovasculature in diabetes.

The Nox1/4 Dual Inhibitor GKT137831 or Nox4 Knockdown Inhibits Angiotensin-II-Induced Adult Mouse Cardiac Fibroblast Proliferation and Migration. AT1 Physically Associates With Nox4.[Pubmed:26445208]

J Cell Physiol. 2016 May;231(5):1130-41.

Both oxidative stress and inflammation contribute to chronic hypertension-induced myocardial fibrosis and adverse cardiac remodeling. Here we investigated whether angiotensin (Ang)-II-induced fibroblast proliferation and migration are NADPH oxidase (Nox) 4/ROS and IL-18 dependent. Our results show that the potent induction of mouse cardiac fibroblast (CF) proliferation and migration by Ang-II is markedly attenuated by Nox4 knockdown and the Nox inhibitor DPI. Further, Nox4 knockdown and DPI pre-treatment attenuated Ang-II-induced IL-18, IL-18Ralpha and collagen expression, and MMP9 and LOX activation. While neutralization of IL-18 blunted Ang-II-induced CF proliferation and migration, knockdown of MMP9 attenuated CF migration. The antioxidant NAC and the cell-permeable SOD mimetics Tempol, MnTBAP, and MnTMPyP attenuated oxidative stress and inhibited CF proliferation and migration. The Nox1/Nox4 dual inhibitor GKT137831 also blunted Ang-II-induced H2 O2 production and CF proliferation and migration. Further, AT1 bound Nox4, and Ang-II enhanced their physical association. Notably, GKT137831 attenuated the AT1/Nox4 interaction. These results indicate that Ang-II induces CF proliferation and migration in part via Nox4/ROS-dependent IL-18 induction and MMP9 activation, and may involve AT1/Nox4 physical association. Thus, either (i) neutralizing IL-18, (ii) blocking AT1/Nox4 interaction or (iii) use of the Nox1/Nox4 inhibitor GKT137831 may have therapeutic potential in chronic hypertension-induced adverse cardiac remodeling.