Thioredoxin in allergic inflammation

Identification of TXN and F5 as novel diagnostic gene biomarkers of the severe asthma based on bioinformatics and machine learning analysis

Asthma poses a major threat to human health. The aim of this study was to identify genetic markers of severe asthma and analyze the relationship between key genes and immune infiltration. Differentially expressed genes (DEGs) were first screened by downloading the training set GSE69683 and validation set GSE137268 from the GEO dataset. SVM-RFE analysis and the LASSO regression model were used to screen key genes, and CIBERSORT was used to assess immune infiltration in the samples. A total of 20 DEGs were identified in this study, mainly enriched for lymph node-like receptors, b-cell receptors, and neutrophil extracellular trap pathway. Comparative validation set GSE137268 identified thioredoxin (TXN) and coagulation factor V (F5) were identified as diagnostic markers of severe asthma. CIBERSORT analysis revealed that TXN and F5 are associated with multiple immune cell infiltrates. In addition, we identified miRNA and TF at the transcriptional level that may regulate F5 and TXN, and found that several commonly used drugs may exert therapeutic effects by targeting F5 and TXN. Taken together, TXN and F5 may be key genes in the development of severe asthma and are associated with immune infiltration. Our study can help to better understand the pathogenesis of asthma and provide new ideas for clinical treatment.

Novel Serum Biomarkers for Patients with Allergic Asthma Phenotype

In distinguishing the allergic asthma (AA) phenotype, it has been identified that specific biomarkers could assist; however, none of them are considered ideal. This study aimed to analyze three groups of biologically active substances in the serum. Twenty steroid-free AA patients, sensitized to Dermatophagoides pteronyssinus, and sixteen healthy subjects (HSs) were enrolled in this study. Blood samples were collected from all patients. Additionally, all AA patients underwent a bronchial allergen challenge (BAC) with Dermatophagoides pteronyssinus, all of which were positive, and blood samples were collected again 24 h later. The concentrations of ten biologically active substances were measured in the serum samples, using enzyme-linked immunosorbent assay (ELISA) and the Luminex® 100/200™ System technology for bead-based multiplex and singleplex immunoassays. Descriptive and analytical statistical methods were used. A p-value of 0.05 or lower was considered statistically significant. The soluble interleukin 5 receptor subunit alpha (sIL-5Rα) and thioredoxin 1 (TRX1) concentrations were significantly increased, whereas those of tyrosine-protein kinase Met (MET), pentraxin 3 (PTX3), and I C-telopeptide of type I collagen (ICTP) were decreased in the AA group compared with the HS group. A significant positive correlation was noted for sIL-5Rα with fractional exhaled nitric oxide (FeNO), blood eosinophil (EOS) count, and total immunoglobulin E (IgE) levels, and a negative correlation was noted with forced expiratory volume in 1 s (FEV1). Moreover, PTX3 showed negative correlations with blood EOS count and total IgE levels, whereas ICTP exhibited a negative correlation with the blood EOS count. In conclusion, this study demonstrated that the serum concentrations of MET, PTX3, TRX1, ICTP, and particularly sIL-5Rα could potentially serve as biomarkers of the AA phenotype.

Identification of an immunodominant IgE epitope of Der f 40, a novel allergen of Dermatophagoides farinae

Background

House dust mites (HDMs), including Dermatophagoides pteronyssinus (Der p) and Dermatophagoides farinae (Der f) species, represent a major source of inhalant allergens that induce IgE-mediated anaphylactic reactions. HDM allergen identification is important to the diagnosis and treatment of allergic diseases. Here, we report the identification of a novel HDM allergen, which we suggest naming Der f 40, and its immunodominant IgE epitopes.

Methods

The recombinant protein Der f 40 was expressed using a pET prokaryotic expression system and purified with Ni-NTA resins. IgE binding activity was evaluated by IgE-western blot, dot-blot, and ELISA. Mast cell activation testing was performed to assess the cellular effects of IgE binding in mouse bone marrow derived mast cells (BMMCs) expressing human FcεRI. IgE binding assays were performed with truncated and hybrid Der f 40 protein molecules to find immunodominant IgE epitopes.

Results

A 106-amino acid (aa) recombinant Der f Group 40 protein (rDer f 40) was obtained (GenBank accession No. XP_046915420.1) as thiredoxin-like protein. Der f 40 was shown to bind IgE from HDM allergic serum in vitro (9.68%; 12/124 in IgE-ELISA), and shown to promote the release of β-hexosaminidase from BMMCs dose-dependently when administered with HDM allergic sera. The Der f Group 40 protein was named Der f 40 and listed in the World Health Organization and International Union of Immunological Societies (WHO/IUIS) Allergen Nomenclature Sub-committee. IgE binding assays with Der f 40-based truncated and hybrid proteins indicated that IgE binding epitopes are likely located in the C-terminal region and dependent on conformational structure. The 76-106-aa region of C-terminus was identified as an immunodominant IgE epitope of Der f 40.

Conclusion

A novel HDM allergen with robust IgE binding activity was identified and named Der f 40. An immunodominant IgE epitope of Der f 40 with conformational dependency was identified in the C-terminus (aa 76-106). These findings provide new information that may be useful in the development of diagnostic and therapeutic agents for HDM allergy.

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.

Thioredoxin-1 Activation by Pterostilbene Protects Against Doxorubicin-Induced Hepatotoxicity via Inhibiting the NLRP3 Inflammasome

Background: Doxorubicin (DOX) has been widely used in cancer treatment. However, DOX can cause a range of significant side effects, of which hepatotoxicity is a common one, and therefore limits its clinical use. Pterostilbene (PTS) has been shown to exhibit anti-oxidant and anti-inflammatory effects in the treatment of liver diseases but whether PTS could protect against hepatotoxicity in DOX-treated mice is unknown.

Methods: In our study, we use C57/BL6J mice and the HepG2 cell line. We divided the mice in 4 groups: the control, the PTS treatment, the DOX treatment, and the DOX + PTS treatment group. Liver histopathology was judged by performing hematoxylin–eosin and Masson staining. Immunohistochemistry was used to perform the expression of NLRP3. The levels of serum alanine transaminase (ALT) and aspartate transaminase (AST) were evaluated. Levels of malondialdehyde (MDA), superoxide dismutase (SOD), glutathione (GSH), and DCFH-DA staining were used to evaluate the oxidative injury. Western blot and real-time PCR were applied to evaluate the expressions of proteins and mRNA. MTT was used to evaluate DOX-induced cell injury and the protective effects of PTS. Recombinant Trx-1 was used to analyze the mechanism of PTS. A TUNEL assay was used to detect apoptosis in DOX-induced HepG2 cells and the protective effects of PTS.

Results: PTS ameliorated DOX-induced liver pathological changes and the levels of AST and ALT. PTS also decreased the level of MDA, increased the level of SOD, GSH, and the expression of Trx-1 in DOX-treated mice. PTS decreased the levels of NLRP3 and IL-1β mRNA and the expressions of their proteins in DOX-treated mice. In addition, PTS also decreased the expression of Cleaved Caspase-3 and BAX and increased the expression of BCL-2. In vitro, after treatment with recombinant Trx-1, ROS and NLRP3 inflammasome were both decreased. Treatment with PTS could rescue the downregulation of Trx-1, decreased the ROS level and the NLRP3 inflammasome, and protected HepG2 cells against DOX-induced apoptosis.

Conclusion: The results show that PTS exhibits protective effects against DOX-induced liver injuries via suppression of oxidative stress, fibrosis, NLRP3 inflammasome stimulation, and cell apoptosis which might lead to a new approach of preventing DOX-induced hepatotoxicity.

Camel whey protein (CWP) ameliorates liver injury in type 2 diabetes mellitus rats and insulin resistance (IR) in HepG2 cells via activation of the PI3K/Akt signaling pathway

This research investigated the effects of camel whey protein (CWP) treatment on type 2 diabetes mellitus (T2DM) rats and insulin resistance (IR) HepG2 cell models. Body weight and fasting blood glucose were observed in type 2 diabetes mellitus (T2DM) rats every week, and biochemical parameters in serum samples were evaluated after 6 weeks. Antioxidant activity in the liver was estimated, and histological examination of the liver tissues was conducted. After CWP treatment, the glucose uptake and lipid accumulation were examined in insulin-resistant HepG2 cells. Our results indicated that CWP mitigated the body weight loss, reversed dyslipidemia, and inhibited the inflammatory response, in T2DM rats. Meanwhile, it protected the liver from being injured by reducing the level of oxidative stress. In the CWP group, the pathological changes were significantly reduced, while the liver lobule structure, liver cell arrangement, as well as congestion, edema, and vacuolization were improved. Our results from quantitative real-time PCR and western blot analyses showed that CWP could up-regulate the expression levels of insulin receptor substrate-2 (IRS-2), phosphoinositide3-kinase (PI3K), protein kinase B (AKT), and glycogen synthase (GS). An active protein component CWP8 was isolated and identified, which was shown to be able to stimulate glycogen synthesis and ameliorate lipid accumulation in IR HepG2 cells. These data indicate that CWP and CWP8 might act as potential natural products regulating glucose and lipid metabolism in T2DM.

Understanding the role of S-nitrosylation/nitrosative stress in inflammation and the role of cellular denitrosylases in inflammation modulation: Implications in health and diseases

S-nitrosylation is a very fundamental post-translational modification of protein and non-protein thiols due the involvement of it in a variety of cellular processes including activation/inhibition of several ion channels such as ryanodine receptor in the cardiovascular system; blood vessel dilation; cGMP signaling and neurotransmission. S-nitrosothiol homeostasis in the cell is tightly regulated and perturbations in homeostasis result in an altered redox state leading to a plethora of disease conditions. However, the exact role of S-nitrosylated proteins and nitrosative stress metabolites in inflammation and in inflammation modulation is not well-reviewed. The cell utilizes its intricate defense mechanisms i.e. cellular denitrosylases such as Thioredoxin (Trx) and S-nitrosoglutathione reductase (GSNOR) systems to combat nitric oxide (NO) pathology which has also gained current attraction as novel anti-inflammatory molecules. This review attempts to provide state-of-the-art knowledge from past and present research on the mechanistic role of nitrosative stress intermediates (RNS, OONO^-, PSNO) in pulmonary and autoimmune diseases and how cellular denitrosylases particularly GSNOR and Trx via imparting opposing effects can modulate and reduce inflammation in several health and disease conditions. This review would also bring into notice the existing gaps in current research where denitrosylases can be utilized for ameliorating inflammation that would leave avenues for future therapeutic interventions.

Quercetin with the potential effect on allergic diseases

Quercetin is a naturally occurring polyphenol flavonoid which is rich in antioxidants. It has anti-allergic functions that are known for inhibiting histamine production and pro-inflammatory mediators. Quercetin can regulate the Th1/Th2 stability, and decrease the antigen-specific IgE antibody releasing by B cells. Quercetin has a main role in anti-inflammatory and immunomodulatory function which makes it proper for the management of different diseases. Allergic diseases are a big concern and have high health care costs. In addition, the use of current therapies such as ß2-agonists and corticosteroids has been limited for long term use due to their numerous side effects. Since the effect of quercetin on allergic diseases has been widely studied, in the current article, we review the effect of quercetin on allergic diseases, such as allergic asthma, allergic rhinitis (AR), and atopic dermatitis (AD).

Antiinflammation and Antioxidant Effects of Thalidomide on Pulmonary Fibrosis in Mice and Human Lung Fibroblasts

In this study, the potential effects of thalidomide (Thal) on bleomycin (BLM)-induced pulmonary fibrosis were investigated. BALB/C mice model of pulmonary fibrosis induced by an intratracheal instillation of BLM was adopted, and then was intraperitoneally injected with Thal (10, 20, 50 mg/kg) daily for 8 days, while the control and BLM-treated mouse groups were injected with a saline solution. The effects of Thal on pulmonary injury were evaluated by the lung wet/dry weight ratios and histopathological examination. Inflammation of lung tissues was assessed by measuring the levels of interleukin (IL)-6, IL-8, tumor necrosis factor (TNF)-α, and transforming growth factor (TGF)-β in bronchoalveolar lavage fluid. Oxidative stress was evaluated by detecting the levels of reactive oxygen species (ROS), superoxide dismutase (SOD), total antioxidant capacity (T-AOC), and malondialdehyde (MDA) in lung tissue. The results indicated that Thal treatment remarkably attenuated pulmonary fibrosis, oxidative stress, and inflammation in mouse lungs. The antiinflammatory and antioxidant effects of Thal were also found in human lung fibroblasts. Thal administration significantly enhanced the activity of thioredoxin reductase; however, the other enzymes or proteins involved in biologic oxidation-reduction equilibrium were not affected. Our findings indicate that Thal-mediated suppression of pulmonary fibrosis is related to the inhibition of oxidative stress and inflammatory response. In summary, these results may provide a rationale to explore clinical application of Thal for the prevention of pulmonary fibrosis.

Eosinophil ETosis and DNA Traps: a New Look at Eosinophilic Inflammation

The traditional paradigm of eosinophils as end-stage damaging cells has mainly relied on their release of cytotoxic proteins. Cytokine-induced cell survival and secretion of granular contents from tissue-dwelling eosinophil are thought to be important mechanisms for eosinophilic inflammatory disorders, although the occurrence of cytolysis and its products (i.e., free extracellular granules) has been observed in affected lesions. Recent evidence indicates that activated eosinophils can exhibit a non-apoptotic cell death pathway, namely extracellular trap cell death (ETosis) that mediates the eosinophil cytolytic degranulation. Here, we discuss the current concept of eosinophil ETosis which provides a new look at eosinophilic inflammation. Lessons from eosinophilic chronic rhinosinusitis revealed that ETosis-derived DNA traps, composed of stable web-like chromatin, contribute to the properties of highly viscous eosinophilic mucin and impairments in its clearance. Intact granules entrapped in DNA traps are causing long-lasting inflammation but also might have immunoregulatory roles. Eosinophils possess a way to have post-postmortem impacts on innate immunity, local immune response, sterile inflammation, and tissue damage.

Thiol redox chemistry: role of protein cysteine oxidation and altered redox homeostasis in allergic inflammation and asthma

Asthma is a pulmonary disorder, with an estimated 300 million people affected worldwide. While it is thought that endogenous reactive oxygen species (ROS) and reactive nitrogen species (RNS) such as hydrogen peroxide and nitric oxide, are important mediators of natural physiological processes, inflammatory cells recruited to the asthmatic airways have an exceptional capacity for producing a variety of highly reactive ROS and RNS believed to contribute to tissue damage and chronic airways inflammation. Antioxidant defense systems form a tightly regulated network that maintains the redox environment of the intra- as well as extracellular environment. Evidence for an oxidant-antioxidant imbalance in asthmatic airways is demonstrated in a number of studies, revealing decreased total antioxidant capacity as well as lower levels of individual antioxidants. Thiols in the form of GSH and sulfhydryl groups of proteins are among the most susceptible oxidant-sensitive targets, and hence, studies investigating protein thiol redox modifications in biology and disease have emerged. This perspective offers an overview of the combined efforts aimed at the elucidation of mechanisms whereby cysteine oxidations contribute to chronic inflammation and asthma, as well as insights into potential cysteine thiol-based therapeutic strategies.

Role of thioredoxin nitration in bleomycin-induced pulmonary fibrosis in rats

Oxidant stimulation has been suggested to play an important role in the pathogenesis of idiopathic pulmonary fibrosis (IPF). Our study aimed to investigate the role and mechanisms of thioredoxin (Trx) nitration during the development of IPF. A rat model of IPF was established by intratracheal instillation of bleomycin (BLM). Male Wistar rats were randomly distributed among the control group and BLM-treated group, in which rats were intratracheally instilled with a single dose of BLM (5.0 mg/kg body mass in 1.0 mL phosphate-buffered saline). At 7 or 28 days after instillation the rats were euthanized. Histopathological and biochemical examinations were performed. The activity and protein level of thioredoxin were assessed. The thioredoxin nitration level was determined using immunoprecipitation and immunoblotting techniques. Our results demonstrated that protein tyrosine nitration increased in the BLM-treated group compared with the control group. Trx activity decreased in the BLM group compared with control group, whereas Trx expression and nitration level increased dramatically in the BLM group compared with the control group. Our results indicated that Trx nitration might be involved in the pathogenesis of IPF.

Signatures of resistance to Lepeophtheirus salmonis include a TH2-type response at the louse-salmon interface

Disease outbreaks with the salmon louse Lepeophtheirus salmonis cause significant economic losses in mariculture operations worldwide. Variable innate immune responses at the louse-attachment site contribute to differences in susceptibility among species such that members of Salmo spp. are more susceptible to infection than those of some Oncorhynchus spp. Relatively little is known about the mechanisms that contribute to disease resistance or susceptibility to L. salmonis in salmon. Here, we utilize histochemistry and transcriptomics in a comparative infection model with susceptible (Atlantic, sockeye) and resistant (coho) salmon. At least three cell populations (MHIIβ+, IL1β+, TNFα+) were activated in coho salmon skin during L. salmonis infection. Locally elevated expression of several pro-inflammatory mediators (e.g. IL1β, IL8, TNFα, COX2, C/EBPβ), and tissue repair enzymes (MMP9, MMP13) were detected in susceptible and resistant species. However, responses specific to coho salmon (e.g. IL4, IL6, TGFβ) or responses shared among susceptible salmon (e.g. SAP, TRF, Cath in Atlantic and sockeye salmon) provide evidence for species-specific pathways contributing to resistance or susceptibility, respectively. Our results confirm the importance of an early pro-inflammatory TH1-type pathway as an initial host response during infection with Pacific sea lice, and demonstrate subsequent regulatory TH2-type processes as candidate defense mechanisms in the skin of resistant coho salmon.

Thioredoxins, glutaredoxins, and peroxiredoxins--molecular mechanisms and health significance: from cofactors to antioxidants to redox signaling

Thioredoxins (Trxs), glutaredoxins (Grxs), and peroxiredoxins (Prxs) have been characterized as electron donors, guards of the intracellular redox state, and "antioxidants". Today, these redox catalysts are increasingly recognized for their specific role in redox signaling. The number of publications published on the functions of these proteins continues to increase exponentially. The field is experiencing an exciting transformation, from looking at a general redox homeostasis and the pathological oxidative stress model to realizing redox changes as a part of localized, rapid, specific, and reversible redox-regulated signaling events. This review summarizes the almost 50 years of research on these proteins, focusing primarily on data from vertebrates and mammals. The role of Trx fold proteins in redox signaling is discussed by looking at reaction mechanisms, reversible oxidative post-translational modifications of proteins, and characterized interaction partners. On the basis of this analysis, the specific regulatory functions are exemplified for the cellular processes of apoptosis, proliferation, and iron metabolism. The importance of Trxs, Grxs, and Prxs for human health is addressed in the second part of this review, that is, their potential impact and functions in different cell types, tissues, and various pathological conditions.

The thioredoxin system as a therapeutic target in human health and disease

The thioredoxin (Trx) system comprises Trx, truncated Trx (Trx-80), Trx reductase, and NADPH, besides a natural Trx inhibitor, the thioredoxin-interacting protein (TXNIP). This system is essential for maintaining the balance of the cellular redox status, and it is involved in the regulation of redox signaling. It is also pivotal for growth promotion, neuroprotection, inflammatory modulation, antiapoptosis, immune function, and atherosclerosis. As an ubiquitous and multifunctional protein, Trx is expressed in all forms of life, executing its function through its antioxidative, protein-reducing, and signal-transducing activities. In this review, the biological properties of the Trx system are highlighted, and its implications in several human diseases are discussed, including cardiovascular diseases, heart failure, stroke, inflammation, metabolic syndrome, neurodegenerative diseases, arthritis, and cancer. The last chapter addresses the emerging therapeutic approaches targeting the Trx system in human diseases.

Proteomic analysis of murine bone marrow niche microenvironment identifies thioredoxin as a novel agent for radioprotection and for enhancing donor cell reconstitution

Hematopoiesis is regulated by the bone marrow (BM) niche microenvironment. We recently found that posttransplant administration of AMD3100 (a specific and reversible CXCR4 antagonist) enhanced donor cell engraftment and promoted recovery of all donor cell lineages in a congeneic mouse transplant model. We hypothesized that AMD3100 enhances donor cell reconstitution in part by modulating the levels and constitution of soluble factors in the niche microenvironment. In the current study, the effects of the BM extracellular fluid (supernatant) from AMD3100-treated transplant recipient mice on colony-forming units (CFUs) were examined. A semiquantitative, mass spectrometry-based proteomics approach was used to screen for differentially expressed proteins between the BM supernatants of PBS-treated transplant mice and AMD3100-treated transplant mice. A total of 178 proteins were identified in the BM supernatants. Thioredoxin was among the 32 proteins that displayed greater than a twofold increase in spectral counts in the BM supernatant of AMD3100-treated transplant mice. We found that thioredoxin increased CFUs in a dose-dependent manner. Thioredoxin improved hematopoiesis in irradiated mice and protected mice from radiation-related death. Furthermore, ex vivo exposure to thioredoxin for 24 hours enhanced the long-term repopulation of hematopoietic stem cells. Additionally, combined posttransplant administration of thioredoxin and AMD3100 improved hematologic recovery in primary and secondary transplant recipient mice. Our studies demonstrated that factors in the BM niche microenvironment play a critical role in hematopoiesis. Identifying these factors provides clues on potential novel targets that can be used to enhance hematologic recovery in hematopoietic stem cell transplan`tation.

Glutaredoxins in thiol/disulfide exchange

SIGNIFICANCE

Glutaredoxins (Grxs) are small oxidoreductases of the thioredoxin family of proteins regulating the thiol redox state of several proteins. Thereby, Grxs are key elements in redox signaling.

RECENT ADVANCES

Redox signaling via protein thiols depends on reversible oxidative modifications induced mainly by reactive oxygen/nitrogen species and glutathione (GSH) in form of its oxidized disulfide or S-nitroso-glutathione. Grxs contribute to redox signaling by the catalysis of glutathionylation, de-glutathionylation, as well as reduction of disulfide bridges via two distinct enzymatic mechanisms. The dithiol mechanism utilizes both active site cysteines to reduce disulfides, whereas the monothiol mechanism utilizes only the N-terminal active site cysteine for the reduction of GSH mixed disulfides. The sphere of action of Grxs continues to grow with the recent identification of novel targets.

CRITICAL ISSUES

Because of limited methodological tools, the identification of new substrates for oxidoreductases in general is one of the biggest challenges in this research area.

FUTURE DIRECTIONS

With this review, we provide a condensed summary of the current knowledge of thiol/disulfide exchange reactions catalyzed by Grxs regarding the mechanistic, structural, and functional aspects. The latter will be of high importance for future research directions, gaining novel insights into redox signaling in general, and the role of Grxs in particular.