TXM peptides inhibit SARS-CoV-2 infection, syncytia formation, and lower inflammatory consequences.

After three years of the SARS-CoV-2 pandemic, the search and availability of relatively low-cost benchtop therapeutics for people not at high risk for a severe disease are still ongoing. Although vaccines and new SARS-CoV-2 variants reduce the death toll, the long COVID-19 along with neurologic symptoms can develop and persist even after a mild initial infection. Reinfections, which further increase the risk of sequelae in multiple organ systems as well as the risk of death, continue to require caution. The spike protein of SARS-CoV-2 is an important target for both vaccines and therapeutics. The presence of disulfide bonds in the receptor binding domain (RBD) of the spike protein is essential for its binding to the human ACE2 receptor and cell entry. Here, we demonstrate that thiol-reducing peptides based on the active site of oxidoreductase thioredoxin 1, called thioredoxin mimetic (TXM) peptides, can prevent syncytia formation, SARS-CoV-2 entry into cells, and infection in a mouse model. We also show that TXM peptides inhibit the redox-sensitive HIV pseudotyped viral cell entry. These results support disulfide targeting as a common therapeutic strategy for treating infections caused by viruses using redox-sensitive fusion. Furthermore, TXM peptides exert anti-inflammatory properties by lowering the activation of NF-κB and IRF signaling pathways, mitogen-activated protein kinases (MAPKs) and lipopolysaccharide (LPS)-induced cytokines in mice. The antioxidant and anti-inflammatory effects of the TXM peptides, which also cross the blood-brain barrier, in combination with prevention of viral infections, may provide a beneficial clinical strategy to lower viral infections and mitigate severe consequences of COVID-19.

The effect of thioredoxin-1 in a rat model of traumatic brain injury depending on diurnal variation.

INTRODUCTION: Traumatic brain injury (TBI) is a public health concern with limited treatment options because it causes a cascade of side effects that are the leading cause of hospital death. Thioredoxin is an enzyme with neuroprotective properties such as antioxidant, antiapoptotic, immune response modulator, and neurogenic, among others; it has been considered a therapeutic target for treating many disorders. METHODS: The controlled cortical impact (CCI) model was used to assess the effect of recombinant human thioredoxin 1 (rhTrx1) (1 µg/2 µL, intracortical) on rats subjected to TBI at two different times of the light-dark cycle (01:00 and 13:00 h). We analyzed the food intake, body weight loss, motor coordination, pain perception, and histology in specific hippocampus (CA1, CA2, CA3, and Dental Gyrus) and striatum (caudate-putamen) areas. RESULTS: Body weight loss, reduced food intake, spontaneous pain, motor impairment, and neuronal damage in specific hippocampus and striatum regions are more evident in rats subjected to TBI in the light phase than in the dark phase of the cycle and in groups that did not receive rhTrx1 or minocycline (as positive control). Three days after TBI, there is a recovery in body weight, food intake, motor impairment, and pain, which is more pronounced in the rats subjected to TBI at the dark phase of the cycle and those that received rhTrx1 or minocycline. CONCLUSIONS: Knowing the time of day a TBI occurs in connection to the neuroprotective mechanisms of the immune response in diurnal variation and the usage of the Trx1 protein might have a beneficial therapeutic impact in promoting quick recovery after a TBI.

Improving effects of telmisartan on spermatogenic disorder induced by fractionated low-dose irradiation in mice.

BACKGROUND: Male infertility is a hot problem worldwide, but there are few treatments, especially male infertility caused by irradiation is difficult to treat. The aim of this study was to investigate and evaluate novel drugs for the treatment of male infertility caused by irradiation. METHODS: we randomly divided 18 male BALB/c mice into 3 groups: control, irradiated, and telmisartan. Both irradiated and telmisartan group completed whole-body 0.5 Gy five times irradiation, and the telmisartan group received intraperitoneal injection of telmisartan (1.2 mg/kg) daily on the next day after irradiation, and all groups were sampled on day 25 after irradiation. RESULTS: Sperm motility results show that total sperm motility of irradiated group was significantly lower compared with control group, and testicular HE results showed that testis in irradiated group were severely damaged. Compared with irradiated group, the total sperm motility, sperm concentration, testicular index, Johnsen score, and the seminiferous tubule layer numbers were higher in telmisartan group (P < 0.05). The immunohistochemical staining showed γ-H2AX expression is higher in telmisartan group compared with irradiated group. And the relative mRNA expression of PLZF, GFRA1, STRA8, DMRT1, SPO11, SYCP2, OVOL2, CCNA1, TJP3, RUNX2, TXNDC2 TNP1, and PRM3 in telmisartan group was all significantly higher than irradiated group (P < 0.05). CONCLUSION: In conclusion, in vivo experiments confirmed that telmisartan ameliorated the spermatogenic disorder in mice caused by fractionated low-dose irradiation via promoting spermatogenesis.

Protective Effects of a Jellyfish-Derived Thioredoxin Fused with Cell-Penetrating Peptide TAT-PTD on H2O2-Induced Oxidative Damage.

Thioredoxin (Trx) plays a critical role in maintaining redox balance in various cells and exhibits anti-oxidative, anti-apoptotic, and anti-inflammatory effects. However, whether exogenous Trx can inhibit intracellular oxidative damage has not been investigated. In previous study, we have identified a novel Trx from the jellyfish Cyanea capillata, named CcTrx1, and confirmed its antioxidant activities in vitro. Here, we obtained a recombinant protein, PTD-CcTrx1, which is a fusion of CcTrx1 and protein transduction domain (PTD) of HIV TAT protein. The transmembrane ability and antioxidant activities of PTD-CcTrx1, and its protective effects against H2O2-induced oxidative damage in HaCaT cells were also detected. Our results revealed that PTD-CcTrx1 exhibited specific transmembrane ability and antioxidant activities, and it could significantly attenuate the intracellular oxidative stress, inhibit H2O2-induced apoptosis, and protect HaCaT cells from oxidative damage. The present study provides critical evidence for application of PTD-CcTrx1 as a novel antioxidant to treat skin oxidative damage in the future.

Thioredoxin A of Streptococcus suis Serotype 2 Contributes to Virulence by Inhibiting the Expression of Pentraxin 3 to Promote Survival Within Macrophages.

Streptococcus suis serotype 2 (SS2) is an important zoonotic pathogen that can infect humans in contact with infected pigs or their byproducts. It can employ different types of genes to defend against oxidative stress and ensure its survival. The thioredoxin (Trx) system is a key antioxidant system that contributes adversity adaptation and pathogenicity. SS2 has been shown to encode putative thioredoxin genes, but the biological roles, coding sequence, and underlying mechanisms remains uncharacterized. Here, we demonstrated that SSU05_0237-ORF, from a clinical SS2 strain, ZJ081101, encodes a protein of 104 amino acids with a canonical CGPC active motif and an identity 70-85% similar to the thioredoxin A (TrxA) in other microorganisms. Recombinant TrxA efficiently catalyzed the thiol-disulfide oxidoreduction of insulin. The deletion of TrxA led to a significantly slow growth and markedly compromised tolerance of the pathogen to temperature stress, as well as impaired adhesion ability to pig intestinal epithelial cells (IPEC-J2). However, it was not involved in H2O2 and paraquat-induced oxidative stress. Compared with the wild-type strain, the ΔTrxA strain was more susceptible to killing by macrophages through increasing NO production. Treatment with TrxA mutant strain also significantly attenuated cytotoxic effects on RAW 264.7 cells by inhibiting inflammatory response and apoptosis. Knockdown of pentraxin 3 in RAW 264.7 cells was more vulnerable to phagocytic activity, and TrxA promoted SS2 survival in phagocytic cells depending on pentraxin 3 activity compared with the wild-type strain. Moreover, a co-inoculation experiment in mice revealed that TrxA mutant strain is far more easily cleared from the body than the wild type strain in the period from 8-24 h, and exhibits significantly attenuated oxidative stress and liver injury. In summary, we reveal the important role of TrxA in the pathogenesis of SS2.

Thioredoxin Interacting Protein Inhibitors in Diabetes Mellitus: A Critical Review.

Diabetes Mellitus (DM) is one of the highest contributors to global mortality, exceeding numbers of even the three major infectious diseases in the world, namely Tuberculosis, HIV AIDS, and Malaria. DM is characterised by increased serum levels of glucose caused by a loss of beta cells of the pancreatic islets, responsible for the secretion of insulin. Upon accumulation of data via a wide array of literature surveys, it has been found that Thioredoxin Interacting Protein (TXNIP) presents itself as a vital factor in controlling the production and loss of beta islet cells. TXNIP inhibits the action of the Thioredoxin (TRX) protein found in the beta cells thereby rendering it ineffective in maintaining the cellular redox balance causing oxidative stress and subsequent consequences ultimately leading to aggravation of the disease. TRX exists in the form of two isoforms - TRX1, which is located in the cytosol and at times translocates to the nucleus, and TRX2, which is located in the nucleus. TRX is responsible for the maintenance of the normal cellular redox balance by reducing the oxidised proteins formed by the Reactive Oxygen Species (ROS) with the help of NADPH dependent TRX Reductase enzyme. This proves to be essential in the pathogenesis of Diabetes Mellitus as the beta cells of the pancreatic islets lack a sufficient amount of antioxidant systems. Thus, inhibition of TXNIP has become essential in the survival of beta cells, not only enhancing insulin secretion and sensitivity but also alleviating the diseases associated with Diabetes. Hence, TXNIP is discovered to be a unique therapeutic target in the management of DM.

Radiotherapy-mediated redox homeostasis-controllable nanomedicine for enhanced ferroptosis sensitivity in tumor therapy.

Ferroptosis has received increasing attentions in cancer therapy owing to its unique advantages over apoptosis. However, ferroptosis is governed by the efficiency of reactive oxygen species (ROS) production and the tumor cell antioxidant microenvironment that compromises therapeutic efficacy of ferroptosis. It is of great significance to develop a strategy that can both achieve high-efficiency ROS production and modulate tumor cell antioxidant microenvironment to amplify ferroptosis. However, until now, such a strategy has rarely been realized. Here, we, for the first time, reported a radiotherapy -mediated redox homeostasis-controllable nanomedicine for amplifying ferroptosis sensitivity in tumor therapy. The nanomedicine is constructed by co-assembling a ferroptosis inducer hemin and a thioredoxin 1 (Trx-1) inhibitor 1-methylpropyl 2-imidazolyl disulfide (PX-12) with human serum albumin. For our nanomedicine, hemin converts H2O2 to ROS via Fenton reaction to induce ferroptosis while PX-12 effectively inhibits the activity of antioxidant Trx-1 to suppress ROS depletion, resulting in amplified ferroptosis. Particularly, combining radiotherapy with the nanomedicine, radiotherapy depletes the other key antioxidant glutathione and generates additional radiotherapy-induced ROS, further boosting the ferroptosis effect. Therefore, our strategy can simultaneously ensure efficient ROS production and regulation of tumor cell antioxidant microenvironment, thereby enhancing efficacy of ferroptosis in tumor therapy. Our work offers an innovative approach to amplify ferroptosis sensitivity against tumors by simultaneously promoting ROS production and regulating redox homeostasis. STATEMENT OF SIGNIFICANCE: The antioxidants such as thioredoxin 1 (Trx-1) and glutathione (GSH) in tumor cells, are significantly upregulated by the innate cancer cellular redox homeostasis, severely restricting the reactive oxygen species (ROS)-based therapy and compromising the effect of Fenton reaction-induced ferroptosis against tumors. It is urgent to develop a strategy to simultaneously achieve Fenton reaction-induced ferroptosis and regulate the cancer cellular redox homeostasis against upregulated levels of Trx-1 and GSH. A radiotherapy-mediated redox homeostasis-regulatable nanomedicine was designed for amplifying ferroptosis sensitivity in tumor therapy, where the therapeutic efficacy of ferroptosis against tumors can be significantly amplified by integrating Fenton reaction-induced and radiotherapy-induced ferroptosis as well as PX-12-enabled inhibition of antioxidant Trx-1 and radiotherapy-induced downregulation of antioxidant GSH levels.

Trx CDSP32-overexpressing tobacco plants improves cadmium tolerance by modulating antioxidant mechanism.

The effects of overexpression of the thioredoxin-like protein CDSP32 (Trx CDSP32) on reactive oxygen species (ROS) metabolism in tobacco leaves exposed to cadmium (Cd) were studied by combining physiological measures and proteomics technology. Thus, the number of differentially expressed proteins (DEPs) in plants overexpressing the Trx CDSP32 gene in tobacco (OE) was observed to be evidently lower than that in wild-type (WT) tobacco under Cd exposure, especially the number of down-regulated DEPs. Cd exposure induced disordered ROS metabolism in tobacco leaves. Although Cd exposure inhibited the activities of superoxide dismutase (SOD), catalase (CAT), and l-ascorbate peroxidase (APX) and the expression of proteins related to the thioredoxin-peroxiredoxin (Trx-Prx) pathway, the increase in the activities of peroxidase (POD), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), glutathione reductase (GR), glutathione peroxidase (GPX), and glutathione S-transferase (GST) and their protein expression levels played an important role in the physiological response to Cd exposure. Notably, Trx CDSP32 was observed to alleviate the decrease in the expression and activities of SOD and CAT caused by Cd exposure and enhance the function of POD. Trx CDSP32 was observed to increase the H2O2 scavenging capacity of the ascorbic acid-glutathione (AsA-GSH) cycle and Trx-Prx pathway under Cd exposure, and it can especially regulate 2-Cys peroxiredoxin (2-Cys Prx) protein expression and thioredoxin peroxidase (TPX) activity. Thus, overexpression of the Trx CDSP32 gene can alleviate the oxidative damage that occurs in tobacco leaves under Cd exposure by modulating antioxidant defense systems.

Multi-Omics Analysis Reveals the Unexpected Immune Regulatory Effects of Arsenene Nanosheets in Tumor Microenvironment.

Arsenene, a two-dimensional (2D) monoelemental layered nanosheet composed of arsenic, was recently reported to feature outstanding anticancer activities. However, the specific biological mechanism of action remains unknown. In this work, we extensively analyzed the mechanism of arsenene in vivo and in vitro and discovered the unexpected immune regulatory capability of arsenene for the first time. Analysis of cell phenotypes in tumor microenvironment by single-cell RNA sequencing revealed that arsenene remodeled the tumor microenvironment by recruiting a high proportion of anticancer immune cells to eliminate the tumor. Mechanistically, arsenene significantly activated T cell receptor signaling pathways to produce antitumor immune cells while inhibiting DNA replication and TCA cycle pathways of tumor cells in vivo. Further proteomic analysis on tumor cells revealed that arsenene induced reactive oxygen species production and oxidative stress damage by targeting thioredoxin TXNL1. The overloaded reactive oxygen species (ROS) further triggered endoplasmic reticulum stress responses to release damage-associated molecular patterns (DAMPs) and "eat-me" signals from dying tumor cells, leading to the activation of antigen-presenting processes to induce the subsequent effector tumor-specific CD8+ T cell immune responses. This unexpected discovery indicated for the first time that 2D inorganic nanomaterials could effectively activate direct anticancer immune responses, suggesting arsenene as a promising candidate nanomedicine for future cancer immunotherapy.

Hypoxia-responsive nanocarriers for chemotherapy sensitization via dual-mode inhibition of hypoxia-inducible factor-1 alpha.

The overexpression of hypoxia-inducible factor-1 alpha (HIF-1α) in solid tumor compromises the potency of chemotherapy under hypoxia. The high level of HIF-1α arises from the stabilization effect of reduced nicotinamideadeninedinucleotide(phosphate) NAD(P)H: quinone oxidoreductase 1 (NQO1). It was postulated that the inhibition of NQO1 could degrade HIF-1α and sensitize hypoxic cancer cells to antineoplastic agents. In the current work, we report hypoxia-responsive polymer micelles, i.e. methoxyl poly(ethylene glycol)-co-poly(aspartate-nitroimidazole) orchestrate with a NQO1 inhibitor (dicoumarol) to sensitize the ovarian cancer cell line (SKOV3) to a model anticancer agent (sorafenib) at low oxygen conditions. Both cargos were physically encapsulated in the nanoscale micelles. The placebo micelles transiently induced the depletion of reduced nicotinamideadeninedinucleotidephosphate (NADPH) as well as glutathione and thioredoxin under hypoxia, which further inactivated NQO1 because NADPH was the cofactor of NQO1. As a consequence, the expression of HIF-1α was repressed due to the dual action of dicoumarol and polymer. The degradation of HIF-1α significantly increased the vulnerability of SKOV3 cells to sorafenib-induced apoptosis, as indicated by the enhancement of cytotoxicity, and increase of caspase 3 and cytochrome C. The current work opens new avenues of addressing hypoxia-induced drug resistance in chemotherapy.

Trifolirhizin regulates the balance of Th17/Treg cells and inflammation in the ulcerative colitis mice through inhibiting the TXNIP-mediated activation of NLRP3 inflammasome.

Ulcerative colitis (UC) is a chronic and recurrent autoimmune disease, characterized by recurrence and remission of mucosal inflammation. Although the understanding of the pathogenesis of UC has been improved, effective therapeutic drugs are required for treating patients with UC. In current work, the mouse model of colitis was established. Trifolirhizin was demonstrated to improve symptom in dextran sulfate sodium (DSS)-induced colitis mice. The body weight of mice was elevated, whereas the disease activity index (DAI) was reduced. Moreover, trifolirhizin was involved in inhibition of inflammation and regulation of the balance of T helper 17 (Th 17) cells and regulatory T (Treg) cells in DSS-induced colitis mice. Further, the activation NLRP3 inflammasome was suppressed by trifolirhizin in DSS-induced colitis mice. Trifolirhizin was also identified to regulate AMP-activated protein kinase (AMPK)-thioredoxin-interacting protein (TXNIP) pathway. The trifolirhizin-mediated anti-inflammatory effect was inhibited by suppressing AMPK in DSS-induced UC mice. In summary, the research suggested that administration of trifolirhizin significantly improved the symptoms and the pathological damage in DSS-induced UC mice. Trifolirhizin regulated the balance of Th17/Treg cells and inflammation in the UC mice through inhibiting the TXNIP-mediated activation of NLRP3 inflammasome.

Overview on Thioredoxin-Interacting Protein (TXNIP): A Potential Target for Diabetes Intervention.

BACKGROUND: Diabetes mellitus (DM) is a common metabolic disorder characterized by a persistent increment of blood glucose. Type 2 DM is characterized by insulin resistance and ß-cell dysfunction. Thioredoxin-interacting protein (TXNIP) is among the factors that control the production and loss of pancreatic ß-cells. OBJECTIVE: Recent studies have shown that high glucose can significantly up-regulate the expression of the TXNIP. Overexpression of TXNIP in ß-cells not only induced apoptosis but also decreased the production of insulin. At the same time, TXNIP deficiency protected the apoptosis of ß-cells, leading to increased insulin production. Therefore, finding small molecules that can modulate TXNIP expression and downstream signalling pathways is essential. Thus, the inhibition of TXNIP has beneficial effects on the cardiovascular system and other tissues such as the heart and the kidney in DM. Therefore, DM treatment must target small TXNIP activity, inhibit expression, and promote endogenous cell mass and insulin production. CONCLUSION: This review briefly describes the effect mechanism, regulatory mechanism, and crystal structure of TXNIP. In addition, we highlight how TXNIP signalling networks contribute to diabetes and interact with drugs that inhibit the development often and its complexes. Finally, the current status and prospects of TXNIP targeted therapy are also discussed.

Protein disulfide isomerases (PDIs) negatively regulate ebolavirus structural glycoprotein expression in the endoplasmic reticulum (ER) via the autophagy-lysosomal pathway.

Zaire ebolavirus (EBOV) causes a severe hemorrhagic fever in humans and non-human primates with high morbidity and mortality. EBOV infection is dependent on its structural glycoprotein (GP), but high levels of GP expression also trigger cell rounding, detachment, and downregulation of many surface molecules that is thought to contribute to its high pathogenicity. Thus, EBOV has evolved an RNA editing mechanism to reduce its GP expression and increase its fitness. We now report that the GP expression is also suppressed at the protein level in cells by protein disulfide isomerases (PDIs). Although PDIs promote oxidative protein folding by catalyzing correct disulfide formation in the endoplasmic reticulum (ER), PDIA3/ERp57 adversely triggered the GP misfolding by targeting GP cysteine residues and activated the unfolded protein response (UPR). Abnormally folded GP was targeted by ER-associated protein degradation (ERAD) machinery and, unexpectedly, was degraded via the macroautophagy/autophagy-lysosomal pathway, but not the proteasomal pathway. PDIA3 also decreased the GP expression from other ebolavirus species but increased the GP expression from Marburg virus (MARV), which is consistent with the observation that MARV-GP does not cause cell rounding and detachment, and MARV does not regulate its GP expression via RNA editing during infection. Furthermore, five other PDIs also had a similar inhibitory activity to EBOV-GP. Thus, PDIs negatively regulate ebolavirus glycoprotein expression, which balances the viral life cycle by maximizing their infection but minimizing their cellular effect. We suggest that ebolaviruses hijack the host protein folding and ERAD machinery to increase their fitness via reticulophagy during infection.Abbreviations: 3-MA: 3-methyladenine; 4-PBA: 4-phenylbutyrate; ACTB: ß-actin; ATF: activating transcription factor; ATG: autophagy-related; BafA1: bafilomycin A1; BDBV: Bundibugyo ebolavirus; CALR: calreticulin; CANX: calnexin; CHX: cycloheximide; CMA: chaperone-mediated autophagy; ConA: concanamycin A; CRISPR: clusters of regularly interspaced short palindromic repeats; Cas9: CRISPR-associated protein 9; dsRNA: double-stranded RNA; EBOV: Zaire ebolavirus; EDEM: ER degradation enhancing alpha-mannosidase like protein; EIF2AK3/PERK: eukaryotic translation initiation factor 2 alpha kinase 3; Env: envelope glycoprotein; ER: endoplasmic reticulum; ERAD: ER-associated protein degradation; ERN1/IRE1: endoplasmic reticulum to nucleus signaling 1; GP: glycoprotein; HA: hemagglutinin; HDAC6: histone deacetylase 6; HMM: high-molecular-mass; HIV-1: human immunodeficiency virus type 1; HSPA5/BiP: heat shock protein family A (Hsp70) member 5; IAV: influenza A virus; IP: immunoprecipitation; KIF: kifenesine; Lac: lactacystin; LAMP: lysosomal associated membrane protein; MAN1B1/ERManI: mannosidase alpha class 1B member 1; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MARV: Marburg virus; MLD: mucin-like domain; NHK/SERPINA1: alpha1-antitrypsin variant null (Hong Kong); NTZ: nitazoxanide; PDI: protein disulfide isomerase; RAVV: Ravn virus; RESTV: Reston ebolavirus; SARS-CoV: severe acute respiratory syndrome coronavirus; SBOV: Sudan ebolavirus; sGP: soluble GP; SQSTM1/p62: sequestosome 1; ssGP: small soluble GP; TAFV: Taï Forest ebolavirus; TIZ: tizoxanide; TGN: thapsigargin; TLD: TXN (thioredoxin)-like domain; Ub: ubiquitin; UPR: unfolded protein response; VLP: virus-like particle; VSV: vesicular stomatitis virus; WB: Western blotting; WT: wild-type; XBP1: X-box binding protein 1.

Thioredoxin upregulation delays diabetes-induced photoreceptor cell degeneration via AMPK-mediated autophagy and exosome secretion.

AIMS: Autophagy and exosome secretion in photoreceptor and RPE cells play an important role during diabetic retinopathy (DR). Thioredoxin (Trx) upregulation delays diabetes-induced photoreceptor cell degeneration, which the effect of autophagy and exosome secretion on it is unclear. Therefore, we investigated the effect of them on Trx upregulation to delay diabetes-induced photoreceptor cell degeneration and to identify the potential therapy for DR in the future. METHODS: Trx-transgenic mice and 661w cell were as models. Retinal function and morphology were evaluated by electroretinography and H&E staining. TUNEL staining was used to evaluate apoptosis. The protein expression was detected by Western blotting. TEM and mRFP-GFP-LC3 method were used to analyze autophagy. RESULTS: In vitro and in vivo, Trx upregulation can delay diabetes-induced photoreceptor cell degeneration. Moreover, the expression of LC3 and p62 was decreasing and the expression of Alix and CD63 was increasing after Trx overexpression. However, it was inhibited after AMPK inhibitor treatment. Additionally, secreted exosomes from photoreceptor were phagocytosed by RPE cells to regulate its physiological function. CONCLUSIONS: Trx upregulation can delay diabetes-induced photoreceptor cell degeneration via AMPK-mediated autophagy and exosome secretion. Secreted exosomes from photoreceptor cells could be phagocytosed and degraded by RPE cells in DR.

Mitochondria play a key role in oxidative stress-induced pancreatic islet dysfunction after severe burns.

BACKGROUND: Severe burns are often complicated with hyperglycemia in part caused by pancreatic islet dysfunction. Previous studies have revealed that in diabetes mellitus, the pancreatic islet dysfunction is partly attributed to oxidative stress. However, the role and mechanism of oxidative stress in hyperglycemia after severe burns remain unclear. Therefore, the purpose of this study was to explore the level and mechanism of oxidative stress in pancreatic islets after severe burns and the antioxidant effect of sodium pyruvate. METHODS: A 30% total body surface area full-thickness burn model was established using male C57BL/6 mice. Fasting blood glucose and glucose-stimulated insulin secretion (GSIS) 24 hours post severe burns were detected. The levels of reactive oxygen species (ROS) and mitochondrial ROS of islets were detected. The activities of complexes in the mitochondrial respiratory chain of islets were measured. The main antioxidant defense system, glutaredoxin system, and thioredoxin system-related indexes were detected, and the expression of manganese superoxide dismutase (Mn-SOD) was measured. In addition, the antioxidant activity of sodium pyruvate was evaluated post severe burns. RESULTS: After severe burns, fasting blood glucose levels increased, while GSIS levels decreased, with significantly elevated ROS levels of pancreatic islets. The activity of complex III decreased and the level of mitochondrial ROS increased significantly post severe burns. For the detoxification of ROS, the expressions of thioredoxin 2, thioredoxin reductase 2, and Mn-SOD located in mitochondria decreased. Sodium pyruvate reduced the level of mitochondrial ROS in islet cells and improved the GSIS of islets after severe burns. CONCLUSION: The high level of mitochondrial ROS of islets is caused by reducing the activity of complex III in mitochondrial respiratory chain, inhibiting mitochondrial thioredoxin system, and downregulating Mn-SOD post severe burns. Sodium pyruvate plays an antioxidant role post severe burns in mice islets and improves the islet function.

Thioredoxin Prevents Loss of UCP2 in Hyperoxia via MKK4-p38 MAPK-PGC1α Signaling and Limits Oxygen Toxicity.

Administration of high concentrations of oxygen (hyperoxia) is one of few available options to treat acute hypoxemia-related respiratory failure, as seen in the current coronavirus disease (COVID-19) pandemic. Although hyperoxia can cause acute lung injury through increased production of superoxide anion (O2•-), the choice of high-concentration oxygen administration has become a necessity in critical care. The objective of this study was to test the hypothesis that UCP2 (uncoupling protein 2) has a major function of reducing O2•- generation in the lung in ambient air or in hyperoxia. Lung epithelial cells and wild-type; UCP2-/-; or transgenic, hTrx overexpression-bearing mice (Trx-Tg) were exposed to hyperoxia and O2•- generation was measured by using electron paramagnetic resonance, and lung injury was measured by using histopathologic analysis. UCP2 expression was analyzed by using RT-PCR analysis, Western blotting analysis, and RNA interference. The signal transduction pathways leading to loss of UCP2 expression were analyzed by using IP, phosphoprotein analysis, and specific inhibitors. UCP2 mRNA and protein expression were acutely decreased in hyperoxia, and these decreases were associated with a significant increase in O2•- production in the lung. Treatment of cells with rhTrx (recombinant human thioredoxin) or exposure of Trx-Tg mice prevented the loss of UCP2 protein and decreased O2•- generation in the lung. Trx is also required to maintain UCP2 expression in normoxia. Loss of UCP2 in UCP2-/- mice accentuated lung injury in hyperoxia. Trx activates the MKK4-p38MAPK (p38 mitogen-activated protein kinase)-PGC1α (PPARγ [peroxisome proliferator-activated receptor γ] coactivator 1α) pathway, leading to rescue of UCP2 and decreased O2•- generation in hyperoxia. Loss of UCP2 in hyperoxia is a major mechanism of O2•- production in the lung in hyperoxia. rhTrx can protect against lung injury in hyperoxia due to rescue of the loss of UCP2.

Sevoflurane attenuates cognitive dysfunction and NLRP3-dependent caspase-1/11-GSDMD pathway-mediated pyroptosis in the hippocampus via upregulation of SIRT1 in a sepsis model.

Septic encephalopathy (SE) is a devastating consequence of sepsis, a hyper-triggered host response against infectious challenge, which ultimately leads to brain damage. The present study examined whether sevoflurane (SVF), a volatile anaesthetic, can counteract the perturbation of homeostasis in a caecal ligation and puncture (CLP)-induced mouse model of SE. SVF enhances neurocognition in terms of spatial memory improvement via counter-regulation of activated oxidative-inflammatory stress and pyroptotic processes in SE. Further, the beneficial effects of SVF against SE are mediated by activation of silent information regulator 1 (SIRT1)-mediated reduction of reactive oxygen species (ROS) level, regulation of thioredoxin (TXN) and thioredoxin interacting protein (TIP) levels, reduction of inflammatory-pyroptotic signalling (NLRP3, caspase 1/11, GSDMD, TLR4 and TRIF) proteins, as well as a reduction of inflammatory cytokine (IL-1ß and IL-18) levels. These findings suggest that SVF may have therapeutic potential for the treatment of SE and associated cognitive malfunction.

Full-coverage regulations of autophagy by ROS: from induction to maturation.

Macroautophagy/autophagy is an evolutionarily well-conserved recycling process in response to stress conditions, including a burst of reactive oxygen species (ROS) production. High level of ROS attack key cellular macromolecules. Protein cysteinyl thiols or non-protein thiols as the major redox-sensitive targets thus constitute the first-line defense. Autophagy is unique, because it removes not only oxidized/damaged proteins but also bulky ROS-generating organelles (such as mitochondria and peroxisome) to restrict further ROS production. The oxidative regulations of autophagy occur in all processes of autophagy, from induction, phagophore nucleation, phagophore expansion, autophagosome maturation, cargo delivery to the lysosome, and finally to degradation of the cargo and recycling of the products, as well as autophagy gene transcription. Mechanically, these regulations are achieved through direct or indirect manners. Direct thiol oxidation of key proteins such as ATG4, ATM and TFEB are responsible for specific regulations in phagophore expansion, cargo recognition and autophagy gene transcription, respectively. Meanwhile, oxidation of certain redox-sensitive chaperone-like proteins (e.g. PRDX family members and PARK7) may impair a nonspecifically local reducing environment in the phagophore membrane, and influence BECN1-involved phagophore nucleation and mitophagy recognition. However, ROS do exhibit some inhibitory effects on autophagy through direct oxidation of key autophagy regulators such as ATG3, ATG7 and SENP3 proteins. SQSTM1 provides an alternative antioxidant mechanism when autophagy is unavailable or impaired. However, it is yet to be unraveled how cells evolve to equip proteins with different redox susceptibility and in their correct subcellular positions, and how cells fine-tune autophagy machinery in response to different levels of ROS.Abbreviations: AKT1/PKB: AKT serine/threonine kinase 1; AMPK: AMP-activated protein kinase; ATG: autophagy related; ATM: ATM serine/threonine kinase; BAX: BCL2 associated X, apoptosis regulator; BECN1: beclin 1; BH3: BCL2-homology-3; CAV1: caveolin 1; CCCP: carbonyl cyanide m-chlorophenylhydrazone; CTSB: cathepsin B; CTSL: cathepsin L; DAPK: death associated protein kinase; ER: endoplasmic reticulum; ETC: electron transport chain; GSH: glutathione; GSTP1: glutathione S-transferase pi 1; H2O2: hydrogen peroxide; HK2: hexokinase 2; KEAP1: kelch like ECH associated protein 1; MAMs: mitochondria-associated ER membranes; MAP1LC3B/LC3: microtubule associated protein 1 light chain 3 beta; MAPK8/JNK1: mitogen-activated protein kinase 8; MAP3K5/ASK1: mitogen-activated protein kinase kinase kinase 5; MCOLN1: mucolipin 1; MMP: mitochondrial membrane potential; MTOR: mechanistic target of rapamycin kinase; NFE2L2/NRF2: nuclear factor, erythroid 2 like 2; NFKB1: nuclear factor kappa B subunit 1; NOX: NADPH oxidase; O2-: superoxide radical anion; p-Ub: phosphorylated Ub; PARK7/DJ-1: Parkinsonism associated deglycase; PE: phosphatidylethanolamine; PEX5: peroxisomal biogenesis factor 5; PINK1: PTEN induced kinase 1; PPP3CA/calcineurin: protein phosphatase 3 catalytic subunit beta; PRDX: peroxiredoxin; PRKAA1: protein kinase AMP-activated catalytic subunit alpha 1; PRKD/PKD: protein kinase D; PRKN/parkin: parkin RBR E3 ubiquitin protein ligase; PtdIns3K: class III phosphatidylinositol 3-kinase; PtdIns3P: phosphatidylinositol-3-phosphate; PTEN: phosphatase and tensin homolog; ROS: reactive oxygen species; SENP3: SUMO specific peptidase 3; SIRT1: sirtuin 1; SOD1: superoxide dismutase 1; SQSTM1/p62: sequestosome 1; SUMO: small ubiquitin like modifier; TFEB: transcription factor EB; TRAF6: TNF receptor associated factor 6; TSC2: TSC complex subunit 2; TXN: thioredoxin; TXNRD1: thioredoxin reductase 1; TXNIP: thioredoxin interacting protein; Ub: ubiquitin; ULK1: unc-51 like autophagy activating kinase 1.

The Role of Thioredoxin/Peroxiredoxin in the ß-Cell Defense Against Oxidative Damage.

Oxidative stress is hypothesized to play a role in pancreatic ß-cell damage, potentially contributing to ß-cell dysfunction and death in both type 1 and type 2 diabetes. Oxidative stress arises when naturally occurring reactive oxygen species (ROS) are produced at levels that overwhelm the antioxidant capacity of the cell. ROS, including superoxide and hydrogen peroxide, are primarily produced by electron leak during mitochondrial oxidative metabolism. Additionally, peroxynitrite, an oxidant generated by the reaction of superoxide and nitric oxide, may also cause ß-cell damage during autoimmune destruction of these cells. ß-cells are thought to be susceptible to oxidative damage based on reports that they express low levels of antioxidant enzymes compared to other tissues. Furthermore, markers of oxidative damage are observed in islets from diabetic rodent models and human patients. However, recent studies have demonstrated high expression of various isoforms of peroxiredoxins, thioredoxin, and thioredoxin reductase in ß-cells and have provided experimental evidence supporting a role for these enzymes in promoting ß-cell function and survival in response to a variety of oxidative stressors. This mini-review will focus on the mechanism by which thioredoxins and peroxiredoxins detoxify ROS and on the protective roles of these enzymes in ß-cells. Additionally, we speculate about the role of this antioxidant system in promoting insulin secretion.

Recombinant Long-Acting Thioredoxin Ameliorates AKI to CKD Transition via Modulating Renal Oxidative Stress and Inflammation.

An effective strategy is highly desirable for preventing acute kidney injury (AKI) to chronic kidney disease (CKD) transition. Thioredoxin-1 (Trx), a redox-active protein that has anti-oxidative and anti-inflammatory properties, would be a candidate for this but its short half-life limits its clinical application. In this study, we examined the renoprotective effect of long-acting Trx that is comprised of human albumin and Trx (HSA-Trx) against AKI to CKD transition. AKI to CKD mice were created by renal ischemia-reperfusion (IR). From day 1 to day 14 after renal IR, the recovery of renal function was accelerated by HSA-Trx administration. On day 14, HSA-Trx reduced renal fibrosis compared with PBS treatment. At the early phase of fibrogenesis (day 7), HSA-Trx treatment suppressed renal oxidative stress, pro-inflammatory cytokine production and macrophage infiltration, thus ameliorating tubular injury and fibrosis. In addition, HSA-Trx treatment inhibited G2/M cell cycle arrest and apoptosis in renal tubular cells. While renal Trx protein levels were decreased after renal IR, the levels were recovered by HSA-Trx treatment. Together, HSA-Trx has potential for use in the treatment of AKI to CKD transition via its effects of modulating oxidative stress and inflammation.