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Topical application of RTA 408 lotion activates Nrf2 in human skin and is well-tolerated by healthy human volunteers.

ABSTRACT: BACKGROUND:Topical application of the synthetic triterpenoid RTA 408 to rodents elicits a potent dermal cytoprotective phenotype through activation of the transcription factor Nrf2. Therefore, studies were conducted to investigate if such cytoprotective properties translate to human dermal cells, and a topical lotion formulation was developed and evaluated clinically. METHODS:In vitro, RTA 408 (3-1000 nM) was incubated with primary human keratinocytes for 16 h. Ex vivo, RTA 408 (0.03, 0.3, or 3 %) was applied to healthy human skin explants twice daily for 3 days. A Phase 1 healthy volunteer clinical study with RTA 408 Lotion (NCT02029716) consisted of 3 sequential parts. In Part A, RTA 408 Lotion (0.5 %, 1 %, and 3 %) and lotion vehicle were applied to individual 4-cm(2) sites twice daily for 14 days. In Parts B and C, separate groups of subjects had 3 % RTA 408 Lotion applied twice daily to a 100-cm(2) site for 14 days or a 500-cm(2) site for 28 days. RESULTS:RTA 408 was well-tolerated in both in vitro and ex vivo settings up to the highest concentrations tested. Further, RTA 408 significantly and dose-dependently induced a variety of Nrf2 target genes. Clinically, RTA 408 Lotion was also well-tolerated up to the highest concentration, largest surface area, and longest duration tested. Moreover, significant increases in expression of the prototypical Nrf2 target gene NQO1 were observed in skin biopsies, suggesting robust activation of the pharmacological target. CONCLUSIONS:Overall, these data suggest RTA 408 Lotion is well-tolerated, activates Nrf2 in human skin, and appears suitable for continued clinical development.

SUBMITTER: Reisman SA

PROVIDER: S-EPMC4501113 | biostudies-literature | 2015 Jul

REPOSITORIES: biostudies-literature

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Topical application of RTA 408 lotion activates Nrf2 in human skin and is well-tolerated by healthy human volunteers.

Reisman Scott A SA Goldsberry Angela R AR Lee Chun-Yue I CY O'Grady Megan L ML Proksch Joel W JW Ward Keith W KW Meyer Colin J CJ

BMC dermatology 20150714

<h4>Background</h4>Topical application of the synthetic triterpenoid RTA 408 to rodents elicits a potent dermal cytoprotective phenotype through activation of the transcription factor Nrf2. Therefore, studies were conducted to investigate if such cytoprotective properties translate to human dermal cells, and a topical lotion formulation was developed and evaluated clinically.<h4>Methods</h4>In vitro, RTA 408 (3-1000 nM) was incubated with primary human keratinocytes for 16 h. Ex vivo, RTA 408 (0 ...[more]

PMID: 26170027

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Project description:ObjectivesMore and more evidence suggests oxidative stress and inflammation contribute importantly to subarachnoid hemorrhage (SAH)-induced cerebral vasospasm and secondary brain injury. Recent evidence indicates Nuclear factor (erythroid-derived 2)-like 2 (Nrf2) increases the expression of antioxidant genes and decreases the expression of pro-inflammatory genes. This study examines the effects of an activator of Nfr2, RTA 408, on SAH-induced cerebral vasospasm and possible mechanism underlying its effect in a two-hemorrhage rodent model of SAH.MethodsWe randomly assigned 60 Sprague-Dawley male rats (350 to 420g) to five groups twelve rats each: one control group (no SAH), one untreated SAH only group and three RTA-408 treatment groups (SAH+ RTA 408 0.5 mg/kg/day, SAH+RTA 408 1 mg/kg/day and a SAH+RTA 408 1.5 mg/kg/day). The treatment groups were administered RTA 408 by intraperitoneal injection thirty min following first induction of SAH for seven days starting with first hemorrhage. Cerebral vasospasm was determined by averaging the cross-sectional areas of basilar artery 7 days after first SAH. Expressions of Nrf2, NF-κB and iNOS in basilar artery and expressions of Nrf2, HO-1, NQO1 and Cleaved caspase-3 were evaluated. Tissue TNF-alpha was assessed by ELISA using the protein sampled from the dentate gyrus, cerebral cortex, and hippocampus.ResultsPrior to perfusion fixation, there were no significant physiological differences among the control and treated groups. RTA 408 treatment attenuated the morphological changes caused by cerebral vasospasm. It mitigated SAH-induced suppression of Nrf2 and increased expression of NF-κB and iNOS in the basilar artery. In dentate gyrus, it reversed SAH-decreases in Nrf2, HO-1, NQO-1 and cleaved caspase-3 and RTA 408 1.5 mg/kg/day reversed SAH increases in TNF-alpha.ConclusionIt was concluded that RTA 408 reversal vasospasm was achieved via increases in Nrf2 and decreases in NF-κB and iNOS. It exerted a neuron-protection effect by decreasing the apoptosis-related protein cleaved caspase-3 and decreasing the information cytokine TNF-alpha expression, which it achieved by increasing HO-1 and NQO-1 protein found downstream from Nrf2 and Nrf2. We believe that RTA 408 can potentially be used to manage of cerebral vasospasm and secondary brain injury following SAH.

Project description:Objective/Hypothesis: To assess the efficacy and mechanism of action of a novel approach to mitigate acute and chronic radiation toxicity in a validated animal model. We propose that synthetic triterpenoid RTA-408, an Nrf2 activator, activates additional protective pathways which stabilize soft tissue during radiation, thereby reducing necrosis and improves surgical outcomes in a subsequently created axial rotational flap. Methods: Experimental animal study utilizing Sprague-Dawley rats were divided into 3 cohorts: (i) radiation + DMSO (inert vehicle), (ii) radiation + RTA-408 (therapeutic drug), and (iii) no radiation + DMSO. Two main groups of rats were utilized in these experiments: (i) rotational flap experiment (n=40) and (ii) transcriptome analysis (n=9). In the first experiment all animals in the radiation cohorts underwent 40 Gy of radiation to the soft tissue of the abdomen. Then all three cohorts underwent surgery with construction of an inferior epigastric axial rotational flap, which was performed 30 days after resolution of acute injury from radiation in the radiation groups. Percentage of flap necrosis, the primary endpoint, was calculated by standardized measurement of tissue necrosis by blinded observers and vascular density measured by CD31 staining. In a second experiment, an additional three cohorts, with identical treatment as described above underwent serial punch biopsies of the abdominal skin before, during, and after radiation and drug/vehicle control treatment. Transcriptome analysis utilizing gene set enrichment analysis and digital PCR were performed at the various timepoints. Results: In the first experiment, 40 rats were divided into the three groups and underwent treatment accordingly. The average flap necrosis was 20% (95% CI, 16-45%) in the radiation control group, 3% (95% CI, 0-11%) in the non-irradiated control, and 3% (95% CI, 0.2-10%) in the radiation group treated with RTA-408. Vascular density was preserved in the treatment group as compared to the radiated control. Nine rats were included in the second experiment, and transcriptome analyses in the treatment group revealed robust activation of antioxidant pathways with induced expression of genes associated with hypoxia and adipogenesis/angiogenesis. Conclusions: Administration of RTA-408 during radiation treatment in a rat model resulted in transcriptome changes which appear to mitigate the toxic effects of radiation, preserving capillary networks and improving flap survival and tissue healing after subsequent surgery. Such reductions in toxicity may have broad implications for functional outcomes and salvage surgery following therapeutic irradiation.

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Topical application of RTA 408 lotion activates Nrf2 in human skin and is well-tolerated by healthy human volunteers.

Publications

Topical application of RTA 408 lotion activates Nrf2 in human skin and is well-tolerated by healthy human volunteers.

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