Redoxisome Update: TRX and TXNIP/TBP2-Dependent Regulation of NLRP-1/NLRP-3 Inflammasome.

Recent studies have provided evidence for the direct binding of thioredoxin-1 (TRX1) to a component of inflammasome complex NLR family pyrin domain containing 1 (NLRP-1). This interaction suggests a potential role for TRX1 in the regulation of the NLRP-1 inflammasome. Furthermore, the NLRP-3 inflammasome is known to bind TRX1 and its inhibitor, TRX-binding protein-2/TRX-interacting protein/vitamin D3 upregulated protein-1 (TBP2/TXNIP/VDUP-1). This binding forms a redox-sensitive complex, termed the "Redoxisome," as described previously. However, the specific functions of NLRP-1 within the redoxisome complex remain undefined. Antioxid. Redox Signal. 40, 595-597.

Geranylgeranylacetone Ameliorates Skin Inflammation by Regulating and Inducing Thioredoxin via the Thioredoxin Redox System.

Geranylgeranylacetone (GGA) exerts cytoprotective activity against various toxic stressors via the thioredoxin (TRX) redox system; however, its effect on skin inflammation and molecular mechanism on inducing the TRX of GGA is still unknown. We investigated the effects of GGA in a murine irritant contact dermatitis (ICD) model induced by croton oil. Both a topical application and oral administration of GGA induced TRX production and Nrf2 activation. GGA ameliorated ear swelling, neutrophil infiltration, and inhibited the expression of TNF-α, IL-1ß, GM-CSF, and 8-OHdG. GGA's cytoprotective effect was stronger orally than topically in mice. In vitro studies also showed that GGA suppressed the expression of NLRP3, TNF-α, IL-1ß, and GM-CSF and scavenged ROS in PAM212 cells after phorbol myristate acetate stimulation. Moreover, GGA induced endogenous TRX production and Nrf2 nuclear translocation in PAM212 cells (dependent on the presence of ROS) and activated the PI3K-Akt signaling pathway. GGA significantly downregulated thioredoxin-interacting protein (TXNIP) levels in PAM212 cells treated with or without Nrf2 siRNA. After knocking down Nrf2 in PAM212 cells, the effect of GGA on TRX induction was significantly inhibited. This suggests that GGA suppress ICD by inducing endogenous TRX, which may be regulated by PI3K/Akt/Nrf2 mediation of the TRX redox system.

Prospect of thioredoxin as a possibly effective tool to combat OSAHS.

PURPOSE: Obstructive sleep apnea-hypopnea syndrome (OSAHS) is characterized by recurrent upper airway disturbances during sleep leading to episodes of hypopnea or apnea, followed by hypoxemia and subsequent reoxygenation. It is believed that this reoxygenation/reperfusion stage leads to oxidative stress, which then leads to inflammation and cardiovascular diseases. The treatments of patient with OSAHS include surgical and non-surgical therapies with various side effects and common complaints. Therefore, it is important to develop a new, safe, and effective therapeutic treatment. As a small-molecule multifunctional protein, thioredoxin (TRX) has antioxidant and redox regulatory functions at the active site Cys-Gly-Pro. TRX prevents inflammation by suppressing the production of pro-inflammatory cytokines rather than suppressing the immune response. METHODS: We review the papers on the pathophysiological process of OSAHS and the antioxidative and anti-inflammatory effects of TRX. RESULTS: TRX may play a role in OSAHS by scavenging ROS, blocking the production of inflammatory cytokines, inhibiting the migration and activation of neutrophils, and controlling the activation of ROS-dependent inflammatory signals by regulating the redox state of intracellular target particles. Furthermore, TRX regulates the synthesis, stability, and activity of hypoxia-inducible factor 1 (HIF-1). TRX also has an inhibitory effect on endoplasmic reticulum- and mitochondria-induced apoptosis by regulating the expression of BAX, BCL2, p53, and ASK1. CONCLUSION: Understanding the function of TRX may be useful for the treatment of OSAHS.

Thioredoxin-1: A Promising Target for the Treatment of Allergic Diseases.

Thioredoxin-1 (Trx1) is an important regulator of cellular redox homeostasis that comprises a redox-active dithiol. Trx1 is induced in response to various stress conditions, such as oxidative damage, infection or inflammation, metabolic dysfunction, irradiation, and chemical exposure. It has shown excellent anti-inflammatory and immunomodulatory effects in the treatment of various human inflammatory disorders in animal models. This review focused on the protective roles and mechanisms of Trx1 in allergic diseases, such as allergic asthma, contact dermatitis, food allergies, allergic rhinitis, and drug allergies. Trx1 plays an important role in allergic diseases through processes, such as antioxidation, inhibiting macrophage migration inhibitory factor (MIF), regulating Th1/Th2 immune balance, modulating allergic inflammatory cells, and suppressing complement activation. The regulatory mechanism of Trx1 differs from that of glucocorticoids that regulates the inflammatory reactions associated with immune response suppression. Furthermore, Trx1 exerts a beneficial effect on glucocorticoid resistance of allergic inflammation by inhibiting the production and internalization of MIF. Our results suggest that Trx1 has the potential for future success in translational research.

Urinary Thioredoxin as a Biomarker of Renal Redox Dysregulation and a Companion Diagnostic to Identify Responders to Redox-Modulating Therapeutics.

Significance: The development and progression of renal diseases, including acute kidney injury (AKI) and chronic kidney disease (CKD), are the result of heterogeneous pathophysiology that reflects a range of environmental factors and, in a lesser extent, genetic mutations. The pathophysiology specific to most kidney diseases is not currently identified; therefore, these diseases are diagnosed based on non-pathological factors. For that reason, pathophysiology-based companion diagnostics for selection of pathophysiology-targeted treatments have not been available, which impedes personalized medicine in kidney disease. Recent Advances: Pathophysiology-targeted therapeutic agents are now being developed for the treatment of redox dysregulation. Redox modulation therapeutics, including bardoxolone methyl, suppresses the onset and progression of AKI and CKD. On the other hand, pathophysiology-targeted diagnostics for renal redox dysregulation are also being developed. Urinary thioredoxin (TXN) is a biomarker that can be used to diagnose tubular redox dysregulation. AKI causes oxidation and urinary excretion of TXN, which depletes TXN from the tubules, resulting in tubular redox dysregulation. Urinary TXN is selectively elevated at the onset of AKI and correlates with the progression of CKD in diabetic nephropathy. Critical Issues: Diagnostic methods should provide information about molecular mechanisms that aid in the selection of appropriate therapies to improve the prognosis of kidney disease. Future Directions: A specific diagnostic method enabling detection of redox dysregulation based on pathological molecular mechanisms is much needed and could provide the first step toward personalized medicine in kidney disease. Urinary TXN is a candidate for a companion diagnostic method to identify responders to redox-modulating therapeutics. Antioxid. Redox Signal. 36, 1051-1065.

Redox Regulation in Aging Lungs and Therapeutic Implications of Antioxidants in COPD.

Mammals, including humans, are aerobic organisms with a mature respiratory system to intake oxygen as a vital source of cellular energy. Despite the essentiality of reactive oxygen species (ROS) as byproducts of aerobic metabolism for cellular homeostasis, excessive ROS contribute to the development of a wide spectrum of pathological conditions, including chronic lung diseases such as COPD. In particular, epithelial cells in the respiratory system are directly exposed to and challenged by exogenous ROS, including ozone and cigarette smoke, which results in detrimental oxidative stress in the lungs. In addition, the dysfunction of redox regulation due to cellular aging accelerates COPD pathogenesis, such as inflammation, protease anti-protease imbalance and cellular apoptosis. Therefore, various drugs targeting oxidative stress-associated pathways, such as thioredoxin and N-acetylcysteine, have been developed for COPD treatment to precisely regulate the redox system. In this review, we present the current understanding of the roles of redox regulation in the respiratory system and COPD pathogenesis. We address the insufficiency of current COPD treatment as antioxidants and discuss future directions in COPD therapeutics targeting oxidative stress while avoiding side effects such as tumorigenesis.

Effect of chronic administration with human thioredoxin-1 transplastomic lettuce on diabetic mice.

SCOPE: Human thioredoxin-1 (hTrx-1) is a defensive protein induced by various stresses and exerts antioxidative and anti-inflammatory effects. Previously, we described a transplastomic lettuce overexpressing hTrx-1 that exerts a protective effect against oxidative damage in a pancreatic ß-cell line. In this study, we treated diabetic mice (Akita mice) with exogenous hTrx-1 and evaluated the effects. METHODS AND RESULTS: Treatment with drinking water and single applications of exogenous hTrx-1 did not influence the feeding, drinking behavior, body weight, blood glucose, or glycosylated hemoglobin (HbA1c) levels in Akita mice. However, chronic administration of a 10% hTrx-1 lettuce-containing diet was associated with a significant reduction from the baseline of HbA1c levels compared with mice fed a wild-type lettuce-containing diet. It also resulted in an increased number of goblet cells in the small intestine, indicating that mucus was synthesized and secreted. CONCLUSION: Our results revealed that the administration of an hTrx-1 lettuce-containing diet improves the baseline level of HbA1c in Akita mice. This effect is mediated through goblet cell proliferation and possibly related to protection against postprandial hyperglycemia by mucus, which results in the improvement of blood glucose control. These findings suggest that the hTrx-1 lettuce may be a useful tool for the continuous antioxidative and antidiabetic efficacies of the hTrx-1 protein.

Progress in the mechanism and targeted drug therapy for COPD.

Chronic obstructive pulmonary disease (COPD) is emphysema and/or chronic bronchitis characterised by long-term breathing problems and poor airflow. The prevalence of COPD has increased over the last decade and the drugs most commonly used to treat it, such as glucocorticoids and bronchodilators, have significant therapeutic effects; however, they also cause side effects, including infection and immunosuppression. Here we reviewed the pathogenesis and progression of COPD and elaborated on the effects and mechanisms of newly developed molecular targeted COPD therapeutic drugs. Among these new drugs, we focussed on thioredoxin (Trx). Trx effectively prevents the progression of COPD by regulating redox status and protease/anti-protease balance, blocking the NF-κB and MAPK signalling pathways, suppressing the activation and migration of inflammatory cells and the production of cytokines, inhibiting the synthesis and the activation of adhesion factors and growth factors, and controlling the cAMP-PKA and PI3K/Akt signalling pathways. The mechanism by which Trx affects COPD is different from glucocorticoid-based mechanisms which regulate the inflammatory reaction in association with suppressing immune responses. In addition, Trx also improves the insensitivity of COPD to steroids by inhibiting the production and internalisation of macrophage migration inhibitory factor (MIF). Taken together, these findings suggest that Trx may be the ideal drug for treating COPD.

Analytical and clinical validation of rapid chemiluminescence enzyme immunoassay for urinary thioredoxin, an oxidative stress-dependent early biomarker of acute kidney injury.

BACKGROUND: Oxidative stress is now recognized to be an important therapeutic target in kidney diseases. However, there are currently no biomarkers that can be used clinically to diagnose renal oxidative stress. METHODS: A rapid assay system for urinary thioredoxin 1, an oxidative stress-dependent biomarker of acute kidney injury (AKI), was developed as a chemiluminescence enzyme immunoassay and validated analytically and clinically. RESULTS: Analytic evaluation revealed that hemolytic hemoglobin caused measurements to be abnormally high, above the detectable range. However, urine sediment containing red blood cells did not affect the measurements. Assays using our proposed chemiluminescence enzyme immunoassay were completed within as little as 6 min, whereas a conventional ELISA > 4 h. Aciduria

Anti-Allergic and Anti-Inflammatory Effects and Molecular Mechanisms of Thioredoxin on Respiratory System Diseases.

Significance: The pathogenesis and progression of allergic inflammation in the respiratory system are closely linked to oxidative stress. Thioredoxin (TRX) is an essential redox balance regulator in organisms and is induced by various oxidative stress factors, including ultraviolet rays, radiation, oxidation, viral infections, ischemia reperfusion, and anticancer agents. Recent Advances: We demonstrated that systemic administration and transgenic overexpression of TRX is useful in a wide variety of in vivo inflammatory respiratory diseases models, such as viral pneumonia, interstitial lung disease, chronic obstructive pulmonary disease, asthma, acute respiratory distress syndrome, and obstructive sleep apnea syndrome, by removing reactive oxygen species, blocking production of inflammatory cytokines, inhibiting migration and activation of neutrophils and eosinophils, and regulating the cellular redox status. In addition, TRX's anti-inflammatory mechanism is different from the mechanisms associated with anti-inflammatory agents, such as glucocorticoids, which regulate the inflammatory reaction in association with suppressing immune responses. Critical Issues: Understanding the molecular mechanism of TRX is very helpful for understanding the role of TRX in respiratory diseases. In this review, we show the protective effect of TRX in various respiratory diseases. In addition, we discuss its anti-allergic and anti-inflammatory molecular mechanism in detail. Future Directions: The application of TRX may be useful for treating respiratory allergic inflammatory disorders. Antioxid. Redox Signal. 32, 785-801.

Thioredoxin-1 maintains mitochondrial function via mechanistic target of rapamycin signalling in the heart.

AIMS: Thioredoxin 1 (Trx1) is an evolutionarily conserved oxidoreductase that cleaves disulphide bonds in oxidized substrate proteins such as mechanistic target of rapamycin (mTOR) and maintains nuclear-encoded mitochondrial gene expression. The cardioprotective effect of Trx1 has been demonstrated via cardiac-specific overexpression of Trx1 and dominant negative Trx1. However, the pathophysiological role of endogenous Trx1 has not been defined with a loss-of-function model. To address this, we have generated cardiac-specific Trx1 knockout (Trx1cKO) mice. METHODS AND RESULTS: Trx1cKO mice were viable but died with a median survival age of 25.5 days. They developed heart failure, evidenced by contractile dysfunction, hypertrophy, and increased fibrosis and apoptotic cell death. Multiple markers consistently indicated increased oxidative stress and RNA-sequencing revealed downregulation of genes involved in energy production in Trx1cKO mice. Mitochondrial morphological abnormality was evident in these mice. Although heterozygous Trx1cKO mice did not show any significant baseline phenotype, pressure-overload-induced cardiac dysfunction, and downregulation of metabolic genes were exacerbated in these mice. mTOR was more oxidized and phosphorylation of mTOR substrates such as S6K and 4EBP1 was impaired in Trx1cKO mice. In cultured cardiomyocytes, Trx1 knockdown inhibited mitochondrial respiration and metabolic gene promoter activity, suggesting that Trx1 maintains mitochondrial function in a cell autonomous manner. Importantly, mTOR-C1483F, an oxidation-resistant mutation, prevented Trx1 knockdown-induced mTOR oxidation and inhibition and attenuated suppression of metabolic gene promoter activity. CONCLUSION: Endogenous Trx1 is essential for maintaining cardiac function and metabolism, partly through mTOR regulation via Cys1483.

Anti-Inflammatory Thioredoxin Family Proteins for Medicare, Healthcare and Aging Care.

Human thioredoxin (TRX) is a 12-kDa protein with redox-active dithiol in the active site -Cys-Gly-Pro-Cys-, which is induced by biological stress due to oxidative damage, metabolic dysfunction, chemicals, infection/inflammation, irradiation, or hypoxia/ischemia-reperfusion. Our research has demonstrated that exogenous TRX is effective in a wide variety of inflammatory diseases, including viral pneumonia, acute lung injury, gastric injury, and dermatitis, as well as in the prevention and amelioration of food allergies. Preclinical and clinical studies using recombinant TRX (rhTRX) are now underway. We have also identified substances that induce the expression of TRX in the body, in vegetables and other plant ingredients. Skincare products are being developed that take advantage of the anti-inflammatory and anti-allergic action of TRX. Furthermore, we are currently engaged in the highly efficient production of pure rhTRX in several plants, such as lettuce, grain and rice.

Thioredoxin-1 maintains mechanistic target of rapamycin (mTOR) function during oxidative stress in cardiomyocytes.

Thioredoxin 1 (Trx1) is a 12-kDa oxidoreductase that catalyzes thiol-disulfide exchange reactions to reduce proteins with disulfide bonds. As such, Trx1 helps protect the heart against stresses, such as ischemia and pressure overload. Mechanistic target of rapamycin (mTOR) is a serine/threonine kinase that regulates cell growth, metabolism, and survival. We have shown previously that mTOR activity is increased in response to myocardial ischemia-reperfusion injury. However, whether Trx1 interacts with mTOR to preserve heart function remains unknown. Using a substrate-trapping mutant of Trx1 (Trx1C35S), we show here that mTOR is a direct interacting partner of Trx1 in the heart. In response to H2O2 treatment in cardiomyocytes, mTOR exhibited a high molecular weight shift in non-reducing SDS-PAGE in a 2-mercaptoethanol-sensitive manner, suggesting that mTOR is oxidized and forms disulfide bonds with itself or other proteins. The mTOR oxidation was accompanied by reduced phosphorylation of endogenous substrates, such as S6 kinase (S6K) and 4E-binding protein 1 (4E-BP1) in cardiomyocytes. Immune complex kinase assays disclosed that H2O2 treatment diminished mTOR kinase activity, indicating that mTOR is inhibited by oxidation. Of note, Trx1 overexpression attenuated both H2O2-mediated mTOR oxidation and inhibition, whereas Trx1 knockdown increased mTOR oxidation and inhibition. Moreover, Trx1 normalized H2O2-induced down-regulation of metabolic genes and stimulation of cell death, and an mTOR inhibitor abolished Trx1-mediated rescue of gene expression. H2O2-induced oxidation and inhibition of mTOR were attenuated when Cys-1483 of mTOR was mutated to phenylalanine. These results suggest that Trx1 protects cardiomyocytes against stress by reducing mTOR at Cys-1483, thereby preserving the activity of mTOR and inhibiting cell death.

Differential expression of thioredoxin binding protein-2/Txnip in human placenta: Possible involvement of hypoxia in its suppression during early pregnancy.

AIM: Thioredoxin binding protein-2 (TBP-2), which is identical to thioredoxin interacting protein (Txnip), controls cellular proliferation and differentiation. The aim of the present study was to compare TBP-2 protein and mRNA expression in human placenta during the three trimesters of pregnancy and to investigate the role of hypoxia in the change of these expressions in placental tissue. A secondary objective was to determine the gene expression of peroxisome proliferator-activated receptors (PPARs) in TBP-2 deficient placenta using TBP-2 gene disrupted mice (TBP-2-/- ). METHODS: Protein and mRNA expression of TBP-2 in human placenta from each trimester were analyzed by immunohistochemistry, Western blots, and by quantitative reverse-transcriptase-polymerase chain reaction. The effect of hypoxia on TBP-2 expression was tested using an explant culture of human placenta. In TBP-2-/- mouse placenta, we detected PPAR mRNA expression. RESULTS: TBP-2 was located in syncytiotrophoblasts and cytotrophoblasts, and also in the endothelium in human placenta. Its expression in the placenta was low in the first trimester, and increased in the second and third trimesters. Hypoxia decreased TBP-2 mRNA and protein expression in human placental explant culture. In TBP-2-/- mice, placental mRNA levels of PPARα and γ were significantly suppressed compared with those in wild-type mice. CONCLUSION: Hypoxia suppresses TBP-2 gene expression, which may ultimately alter placental development.

Axonal protection by thioredoxin-1 with inhibition of interleukin-1ß in TNF-induced optic nerve degeneration.

Interleukin (IL)-1ß, a proinflammatory cytokine, is a key mediator in several acute and chronic neurological diseases. Thioredoxin-1 (TRX1) acts as an antioxidant and plays a protective role in certain neurons. We examined whether exogenous TRX1 exerts axonal protection and affects IL-1ß levels in tumor necrosis factor (TNF)-induced optic nerve degeneration in rats. Immunoblot analysis showed that IL-1ß was upregulated in the optic nerve after intravitreal injection of TNF. Treatment with recombinant human (rh) TRX1 exerted substantial protective effects against TNF-induced axonal loss. The increase in the IL-1ß level in the optic nerve was abolished by rhTRX1. Treatment with rhTRX1 also significantly inhibited increased glial fibrillary acidic protein (GFAP) levels induced by TNF. Immunohistochemical analysis showed substantial colocalization of IL-1ß and GFAP in the optic nerve after TNF injection. These results suggest that IL-1ß is upregulated in astrocytes in the optic nerve after TNF injection and that exogenous rhTRX1 exerts axonal protection with an inhibitory effect on IL-1ß.

Human thioredoxin-1 attenuates the rate of lipopolysaccharide-induced preterm delivery in mice in association with its anti-inflammatory effect.

BACKGROUND: Maternal intrauterine infection/inflammation represents the major etiology of preterm delivery and the leading cause of neonatal mortality and morbidity. The aim of this study was to investigate the anti-inflammatory properties of thioredoxin-1 in vivo and its potential ability to attenuate the rate of inflammation-induced preterm delivery. METHODS: Two intraperitoneal injections of lipopolysaccharide from Escherichia coli were administered in pregnant mice on gestational day 15, with a 3-h interval between the injections. From either 1 h before or 1 h after the first lipopolysaccharide injection, mice received three intravenous injections of either recombinant human thioredoxin-1, ovalbumin, or vehicle, with a 3-h interval between injections. RESULTS: Intraperitoneal injection of lipopolysaccharide induced a rise of tumor necrosis factor-α, interferon-γ, monocyte chemotactic protein 1, and interleukin-6 in maternal serum levels and provoked preterm delivery. Recombinant human thoredoxin-1 prevented the rise in these proinflammatory cytokine levels. After the inflammatory challenge, placentas exhibited severe maternal vascular dilatation and congestion and a marked decidual neutrophil activation. These placental pathological findings were ameliorated by recombinant human thioredoxin-1, and the rate of inflammation-induced preterm delivery was attenuated. CONCLUSION: Thioredoxin-1 may thus represent a novel effective treatment to delay inflammation-induced preterm delivery.

Thiol redox barrier; local and systemic surveillance against stress and inflammatory diseases.

A 12-kDa protein with redox-active dithiol in the active site -Cys-Gly-Pro-Cys-, human thioredoxin 1 (TRX) has demonstrated an excellent anti-inflammatory effect in various animal models. TRX is induced by various oxidative stress factors, including ultraviolet rays, radiation, oxidation, viral infections, ischemia reperfusion and anticancer agents, and are involved in the pathogenesis and progression of various diseases. We have demonstrated that systemic administration and transgenic overexpression of TRX is effective in a wide variety of in vivo inflammatory disease models, such as viral pneumonia, acute lung injury, chronic obstructive pulmonary disease, indomethacin-induced gastric injury, and dermatitis. Our recent studies indicate that topically applied TRX prevents skin inflammation via the inhibition of local formation of inflammatory cytokines and chemokines. These indicate that the activation of inflammasome in skin and mucosa may be regulated by TRX. These suggest that application of TRX may be useful for the treatment of various skin and mucosal inflammatory disorders. Based on these results, we are conducting clinical studies to develop human recombinant thioredoxin 1 (rhTRX) pharmaceuticals. We have also developed substances that increase the expression of TRX in the body (TRX-inducing substances) in vegetables and other plant ingredients, and we are also developing skin-care products and functional foods that take advantage of the anti-inflammation and anti-allergic action of TRX.

Induction of thioredoxin-1 in response to oxidative stress in dogs.

OBJECTIVE: To determine whether thioredoxin (TRX)-1 can be used as a valid biomarker for oxidative stress in dogs. ANIMALS AND SAMPLES: 10 Beagles and Madin-Darby canine kidney cells. PROCEDURES: Madin-Darby canine kidney cells were used to verify antigen cross-reactivity between human and canine anti-TRX-antibodies. Dogs were assigned to receive 21% or 100% O2 (5 dogs/group) via an artificial respirator during a 3-hour period of isoflurane anesthesia (starting at 0 hours). Blood and urine samples were collected before (baseline) and at 6, 12, 24, and 48 hours after commencement of inhalation anesthesia. Concentrations of TRX-1 and 8-hydroxy-2'-deoxyguanosine (8-OHdG) in plasma and urine samples were analyzed; urine concentrations were reported as ratios against urine creatinine concentration. RESULTS: Canine TRX-1 was recognized by monoclonal human anti-TRX-1 antibodies (clones of adult T-cell leukemia-derived factor [ADF]-11 and ADF21) by western blot analysis. Results of an ELISA indicated that plasma TRX-1 concentration and urine TRX-1-to-creatinine concentration ratio increased rapidly after the 3-hour period of hyperoxia with maximal peaks at 12 and 6 hours, respectively. Urine 8-OHdG-to-creatinine concentration ratio also increased significantly after hyperoxia induction. However, unlike the rapid increase in urine TRX-1-to-creatinine concentration ratio, maximal urine 8-OHdG-to-creatinine concentration ratio was attained at 48 hours after hyperoxia induction. These variables remained unchanged from baseline in the control group. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that human anti-TRX monoclonal antibodies cross-reacted with canine TRX, and plasma TRX-1 concentrations were rapidly increased in dogs following an oxidative stress challenge. Thus, TRX may be a valuable clinical biomarker for detecting oxidative stress more rapidly than 8-OHdG in dogs.

Renal redox dysregulation in AKI: application for oxidative stress marker of AKI.

Oxidative stress is a major determinant of acute kidney injury (AKI); however, the effects of an AKI on renal redox system are unclear, and few existing AKI markers are suitable for evaluating oxidative stress. We measured urinary levels of the redox-regulatory protein thioredoxin 1 (TRX1) in patients with various kinds of kidney disease and in mice with renal ischemia-reperfusion injury. Urinary TRX1 levels were markedly higher in patients with AKI than in those with chronic kidney disease or in healthy subjects. In a receiver operating characteristic curve analysis to differentiate between AKI and other renal diseases, the area under the curve for urinary TRX1 was 0.94 (95% confidence interval, 0.90-0.98), and the sensitivity and specificity were 0.88 and 0.88, respectively, at the optimal cutoff value of 43.0 µg/g creatinine. Immunostaining revealed TRX1 to be diffusely distributed in the tubules of normal kidneys, but to be shifted to the brush borders or urinary lumen in injured tubules in both mice and humans with AKI. Urinary TRX1 in AKI was predominantly in the oxidized form. In cultured human proximal tubular epithelial cells, hydrogen peroxide specifically and dose dependently increased TRX1 levels in the culture supernatant, while reducing intracellular levels. These findings suggest that urinary TRX1 is an oxidative stress-specific biomarker useful for distinguishing AKI from chronic kidney disease and healthy kidneys.