NOX4 inhibition potentiates immunotherapy by overcoming cancer-associated fibroblast-mediated CD8 T-cell exclusion from tumours

Determining mechanisms of resistance to PD-1/PD-L1 immune checkpoint immunotherapy is key to developing new treatment strategies. Cancer-associated fibroblasts (CAF) have many tumor-promoting functions and promote immune evasion through multiple mechanisms, but as yet, there are no CAF-specific inhibitors clinically available. Here we generated CAF-rich murine tumor models (TC1, MC38, 4T1) to investigate how CAF influence the immune microenvironment and affect response to different immunotherapy modalities (anti-cancer vaccination; TC1, [HPV E7 DNA vaccine];PD-1, MC38) and found that CAFs broadly suppressed response by specifically excluding CD8+ T-cells from tumors (not CD4+ T-cells or macrophages); CD8+ T-cell exclusion was similarly present in CAF-rich human tumors. RNA sequencing of CD8+ T-cells from CAF-rich murine tumors and immunochemistry analysis of human tumors identified significant upregulation of CTLA-4 in the absence of other exhaustion markers; inhibiting CTLA-4 with a non-depleting antibody overcame the CD8+ T-cell exclusion effect without affecting T-regs. We then examined the potential for CAF targeting, focusing on the ROS-producing enzyme NOX4, which is upregulated by CAF in many human cancers, and compared this to TGF-062;1 inhibition, a key regulator of the CAF phenotype. siRNA knockdown or pharmacological inhibition (GKT137831 [Setanaxib]) of NOX4 'normalized' CAF to a quiescent phenotype and promoted intratumoral CD8+T-cell infiltration, overcoming the exclusion effect; TGF-062;1 inhibition could prevent, but not reverse, CAF differentiation. Finally, NOX4 inhibition restored immunotherapy response in CAF-rich tumors. These findings demonstrate that CAF-mediated immunotherapy resistance can be effectively overcome through NOX4 inhibition, and could improve outcome in a broad range of cancers

AS601245 (1,3-benzothiazol-2-yl (2-[[2-(3-pyridinyl) ethyl] amino]-4 pyrimidinyl) acetonitrile): a c-Jun NH2-terminal protein kinase inhibitor with neuroprotective properties

Recent evidence suggests that activation of the c-Jun NH2-terminal protein kinase (JNK) signal transduction pathway may play a role in ischemia-induced cell death. Thus, preventing the activation of JNK, or c-Jun phosphorylation could be neuroprotective. In the current study, we report that a small molecule, AS601245 (1,3-benzothiazol-2-yl (2-[[2-(3-pyridinyl) ethyl] amino]-4 pyrimidinyl) acetonitrile), which has been shown to inhibit the JNK signaling pathway, promotes cell survival after cerebral ischemia. In vivo, AS601245 (40, 60, and 80 mg/kg) administered i.p. provided significant protection against the delayed loss of hippocampal CA1 neurons in a gerbil model of transient global ischemia. This effect is mediated by JNK inhibition and therefore by c-Jun expression and phosphorylation. A significant neuroprotective effect of AS601245 administered either by i.p. injection (6, 18, and 60 mg/kg) or as i.v. bolus (1 mg/kg) followed by an i.v. infusion (0.6 mg/kg/h) was also observed in rats after focal cerebral ischemia. These data suggest that the use of JNK inhibitors such as AS601245 may be a relevant strategy in the therapy of ischemic insults

Combined Nox1/4 inhibition with GKT137831 in mice provides dose-dependent reno- and atheroprotection even in established micro- and macrovascular disease

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

NOX4-derived reactive oxygen species limit fibrosis and inhibit proliferation of vascular smooth muscle cells in diabetic atherosclerosis

Smooth muscle cell (SMC) proliferation and fibrosis contribute to the development of advanced atherosclerotic lesions. Oxidative stress caused by increased production or unphysiological location of reactive oxygen species (ROS) is a known major pathomechanism. However, in atherosclerosis, in particular under hyperglycaemic/diabetic conditions, the hydrogen peroxide-producing NADPH oxidase type 4 (NOX4) is protective. Here we aim to elucidate the mechanisms underlying this paradoxical atheroprotection of vascular smooth muscle NOX4 under conditions of normo- and hyperglycaemia both in vivo and ex vivo. Following 20-weeks of streptozotocin-induced diabetes, Apoe(-/-) mice showed a reduction in SM-alpha-actin and calponin gene expression with concomitant increases in platelet-derived growth factor (PDGF), osteopontin (OPN) and the extracellular matrix (ECM) protein fibronectin when compared to non-diabetic controls. Genetic deletion of Nox4 (Nox4(-/-)Apoe(-/-)) exacerbated diabetes-induced expression of PDGF, OPN, collagen I, and proliferation marker Ki67. Aortic SMCs isolated from NOX4-deficient mice exhibited a dedifferentiated phenotype including loss of contractile gene expression, increased proliferation and ECM production as well as elevated levels of NOX1-associated ROS. Mechanistic studies revealed that elevated PDGF signalling in NOX4-deficient SMCs mediated the loss of calponin and increase in fibronectin, while the upregulation of NOX1 was associated with the increased expression of OPN and markers of proliferation. These findings demonstrate that NOX4 actively regulates SMC pathophysiological responses in diabetic Apoe(-/-) mice and in primary mouse SMCs through the activities of PDGF and NOX1

Nox4 inhibition, by GKT 137831, decreases obesity-associated vascular dysfunction and pro-fibrotic effects

The pathophysiological role of Nox4 remains elusive and controversial. Even though Nox4 expression is increased in hypertension, diabetes and obesity, some studies demonstrate that Nox4 deficiency predisposes to obesity and insulin resistance. We showed that Nox1/4 inhibition is renoprotective in diabetes. Whether Nox4 influences vascular function and kidney status in obesity associated with mild diabetes is unclear. We hypothesized that Nox4-specific inhibition is protective against obesity-associated vascular and kidney damage. We studied db/m (control) and db/db mice (obese) mice for 16 weeks receiving 1) vehicle; 2) low dose Nox4 inhibitor, GKT137831 (GKT) (20 mg) and 3) high dose GKT (60 mg) for 16 weeks. Body weight increased in db/db (61.8g ± 0.95) versus controls (33.5g ± 0.72, p<0.05). Plasma glucose and albuminuria were slightly increased in db/db. GKT did not influence body weight but reduced epididymal fat mass in db/db (20% increase, p<0.05). Blood pressure was similar in all groups. Kidney weight (25%) and markers of renal fibrosis, such as, fibronectin (60%), pro-collagen I (PCI - 50%) and TGFβ (30%), were increased in db/db versus controls (p<0.05). High dose GKT decreased renal expression of fibronectin and PCI in db/db. Renal ERK1/2 activation was ameliorated by high dose GKT in db/db (vehicle, 65% vs GKT, 2.3%, p<0.05). Plasma 8-isoprostanes (db/db: 1263±96 vs db/m: 936±35), marker of systemic oxidative stress, and kidney hydrogen peroxide (db/db: 1 fold increase vs db/m) levels were increased in db/db, effects blocked by GKT. Endothelial dysfunction in db/db mice was not affected by GKT, but decreased NE-induced vascular contraction in db/db (pD2: db/db vs. db/db high dose, 6.4±0.1 vs. 5.6 ± 0.1, p<0.001). Reduced contraction by GKT was associated with decreased Rho kinase activity (db/db: 84% increase vs db/db+GKT 60 mg: 29% increase, p<0.05). Our findings suggest a role for Nox4 in obesity-associated kidney and vascular damage/dysfunction, important factors predisposing to cardiovascular disease in obesity. Mechanisms underlying Nox4 effects involve oxidative stress and Rho kinase

The Nox4 inhibitor GKT137831, prevents aldosterone production by adipocytes and protects against adipose tissue inflammation and fibrosis in obese mice

Aldosterone (aldo) plays an important role in obesity-associated cardiovascular risk. We demonstrated that aldo is produced by adipocytes, an effect associated with increased generation of reactive oxygen species (ROS). These processes are exaggerated in obesity. The relationship between adipocyte aldosterone and ROS is unclear. We postulated that Nox4-derived ROS is important for aldo production in adipocytes and leads to a pro-inflammatory phenotype in obesity. Studies were performed in db/m (lean) and db/db (obese) mice, treated with low (20mg/kg/day) or high dose (60mg/kg/day) GKT137831 (GKT, Nox4 inhibitor, 16 weeks). Epididymal (EVAT) and perivascular (PVAT) fat were collected. Plasma and adipocyte aldo were measured by ELISA. Adipose tissue fibrosis was evaluated by picro Sirius red staining and inflammatory mediators by immunostudies. Body weight was increased in db/db mice (61.8g vs control 33.5g), with no effect of GKT. Epididymal adiposity was increased in db/db mice (0.098g vs. 0.067g, p<0.05). Plasma aldo levels in db/db (pg/mL: 518 vs. 272g) and aldo levels in culture media from db/db adipocytes were increased (pg/mL/μg RNA: 1964 vs. 388), p<0.05. All effects decreased by high dose GKT. In PVAT, CYP11B2 gene expression was increased in db/db (2.6±0.8 vs control 1.1±0.1, p<0.05), an effect blocked by Nox4 inhibition. Gene expression of adipocyte differentiation marker, AP2, was increased (3.5±1.1 vs control 1.4±0.4) while anti-inflammatory marker adiponectin was decreased (0.7±0.1 vs control 1.3±0.2, p<0.05)) in obese mice. GKT decreased AP2 levels. Adipocyte-derived TNFα was increased in db/db (4.9±1.8 vs control 1.6±0.6, p<0.05), an effect blocked by GKT. Pro-collagen I, marker of fibrosis, was increased in db/db mice (132±11 vs control 87±4, p<0.05). Sirius red staining was exaggerated in EVAT from db/db mice, and decreased by Nox4 inhibition. In conclusion, Nox4 plays a role in regulating adipocyte-derived aldosterone and promotes a pro-inflammatory and profibrotic adipose phenotype in obese db/db mice. These findings suggest that adipocyte Nox4 links hyperaldosteronism and inflammation/fibrosis in adiposity and as such may be a putative therapeutic target for obesity-associated cardiovascular damage

Genetic Targeting or Pharmacologic Inhibition of NADPH Oxidase Nox4 Provides Renoprotection in Long-Term Diabetic Nephropathy

Diabetic nephropathy may occur, in part, as a result of intrarenal oxidative stress. NADPH oxidases comprise the only known dedicated reactive oxygen species (ROS)–forming enzyme family. In the rodent kidney, three isoforms of the catalytic subunit of NADPH oxidase are expressed (Nox1, Nox2, and Nox4). Here we show that Nox4 is the main source of renal ROS in a mouse model of diabetic nephropathy induced by streptozotocin administration in ApoE−/− mice. Deletion of Nox4, but not of Nox1, resulted in renal protection from glomerular injury as evidenced by attenuated albuminuria, preserved structure, reduced glomerular accumulation of extracellular matrix proteins, attenuated glomerular macrophage infiltration, and reduced renal expression of monocyte chemoattractant protein-1 and NF-κB in streptozotocin-induced diabetic ApoE−/− mice. Importantly, administration of the most specific Nox1/4 inhibitor, GKT137831, replicated these renoprotective effects of Nox4 deletion. In human podocytes, silencing of the Nox4 gene resulted in reduced production of ROS and downregulation of proinflammatory and profibrotic markers that are implicated in diabetic nephropathy. Collectively, these results identify Nox4 as a key source of ROS responsible for kidney injury in diabetes and provide proof of principle for an innovative small molecule approach to treat and/or prevent chronic kidney failure

Hepatocyte Nicotinamide Adenine Dinucleotide Phosphate Reduced Oxidase 4 Regulates Stress Signaling, Fibrosis, and Insulin Sensitivity During Development of Steatohepatitis in Mice.

Background & aimsReactive oxidative species (ROS) are believed to be involved in the progression of nonalcoholic steatohepatitis (NASH). However, little is known about the sources of ROS in hepatocytes or their role in disease progression. We studied the effects of nicotinamide adenine dinucleotide phosphate reduced oxidase 4 (NOX4) in liver tissues from patients with NASH and mice with steatohepatitis.MethodsLiver biopsy samples were obtained from 5 patients with NASH, as well as 4 patients with simple steatosis and 5 patients without steatosis (controls) from the University of California, Davis Cancer Center Biorepository. Mice with hepatocyte-specific deletion of NOX4 (NOX4(hepKO)) and NOX4(floxp+/+) C57BL/6 mice (controls) were given fast-food diets (supplemented with high-fructose corn syrup) or choline-deficient l-amino acid defined diets to induce steatohepatitis, or control diets, for 20 weeks. A separate group of mice were given the NOX4 inhibitor (GKT137831). Liver tissues were collected and immunoblot analyses were performed determine levels of NOX4, markers of inflammation and fibrosis, double-stranded RNA-activated protein kinase, and phospho-eIF-2α kinase-mediated stress signaling pathways. We performed hyperinsulinemic-euglycemic clamp studies and immunoprecipitation analyses to determine the oxidation and phosphatase activity of PP1C.ResultsLevels of NOX4 were increased in patients with NASH compared with controls. Hepatocyte-specific deletion of NOX4 reduced oxidative stress, lipid peroxidation, and liver fibrosis in mice with diet-induced steatohepatitis. A small molecule inhibitor of NOX4 reduced liver inflammation and fibrosis and increased insulin sensitivity in mice with diet-induced steatohepatitis. In primary hepatocytes, NOX4 reduced the activity of the phosphatase PP1C, prolonging activation of double-stranded RNA-activated protein kinase and phosphorylation of extracellular signal-regulated kinase-mediated stress signaling. Mice with hepatocyte-specific deletion of NOX4 and mice given GKT137831 had increased insulin sensitivity.ConclusionsNOX4 regulates oxidative stress in the liver and its levels are increased in patients with NASH and mice with diet-induced steatohepatitis. Inhibitors of NOX4 reduce liver inflammation and fibrosis and increase insulin sensitivity, and might be developed for treatment of NASH

Targeting the myofibroblastic cancer-associated fibroblast phenotype through inhibition of NOX4

Background: Cancer-associated fibroblasts (CAFs) are tumour-promoting and correlate with poor survival in many cancers, which has led to their emergence as potential therapeutic targets. However, effective methods to manipulate these cells clinically have yet to be developed. Methods: CAF accumulation and prognostic significance in head and neck cancer (oral, n ¼ 260; oropharyngeal, n ¼ 271), and colorectal cancer (n ¼ 56) was analyzed using immunohistochemistry. Mechanisms regulating fibroblast-to-myofibroblast transdifferentiation were investigated in vitro using RNA interference/pharmacological inhibitors followed by polymerase chain reaction (PCR), immunoblotting, immunofluorescence, and functional assays. RNA sequencing/bioinformatics and immunohistochemistry were used to analyze NAD(P)H Oxidase-4 (NOX4) expression in different human tumors. NOX4’s rolein CAF-mediated tumor progression was assessed in vitro, using CAFs from multiple tissues in Transwell and organotypicculture assays, and in vivo, using xenograft (n ¼ 9–15 per group) and isograft (n ¼ 6 per group) tumor models. All statistical tests were two-sided.Results: Patients with moderate/high levels of myofibroblastic-CAF had a statistically significant decrease in cancer-specificsurvival rates in each cancer type analyzed (hazard ratios [HRs] ¼ 1.69–7.25, 95% confidence intervals [CIs] ¼ 1.11 to 31.30,log-rank P .01). Fibroblast-to-myofibroblast transdifferentiation was dependent on a delayed phase of intracellular reactive oxygen species, generated by NOX4, across different anatomical sites and differentiation stimuli. A statistically significantupregulation of NOX4 expression was found in multiple human cancers (P < .001), strongly correlating with myofibroblastic CAFs(r ¼ 0.65–0.91, adjusted P < .001). Genetic/pharmacological inhibition of NOX4 was found to revert the myofibroblastic CAF phenotype ex vivo (54.3% decrease in a-smooth muscle actin [a-SMA], 95% CI ¼ 10.6% to 80.9%, P ¼ .009), prevent myofibroblastic-CAF accumulation in vivo (53.2%–79.0% decrease in a-SMA across different models, P .02) and slow tumor growth (30.6%–64.0% decrease across different models, P .04).Conclusions: These data suggest that pharmacological inhibition of NOX4 may have broad applicability for stromal targeting across cancer types