The Role of NOX4 and TRX2 in Angiogenesis and Their Potential Cross-Talk

Thioredoxin-2 suppresses hydrogen peroxide-activated nuclear factor kappa B signaling via alleviating oxidative stress in bovine adipocytes

During the periparturient period, both oxidative stress, and inflammation of adipose tissue are considered high risk factors for metabolic disorder of dairy cows. Oxidative stress can activate transcription factor nuclear factor kappa B (NF-κB), which lead to the upregulation of genes involved in inflammatory pathways. Thioredoxin-2 (TXN2) is a mitochondrial protein that regulates cellular redox by suppressing mitochondrial reactive oxygen species (ROS) generation in nonruminant, whereas the function of TXN2 in bovine adipocytes was unclear. Thus, the objective of this study was to evaluate how or by which mechanisms TXN2 regulates oxidative stress and NF-κB signaling pathway in bovine adipocytes. Bovine pre-adipocytes isolated from 5 healthy Holstein cows were differentiated and used for (1) treatment with different concentrations of hydrogen peroxide (H2O2; 0, 25, 50, 100, 200, or 400 μM) for 2 h; (2) transfection with or without TXN2 small interfering RNA (si-TXN2) for 48 h and then treated with or without 200 μM H2O2 for 2 h; (3) transfection with scrambled negative control siRNA (si-control) or si-TXN2 for 48 h, and then treatment with or without 10 mM N-acetylcysteine (NAC) for 2 h; (4) transfection with or without TXN2-overexpressing plasmid for 48 h and then treatment with or without 200 μM H2O2 for 2 h. High concentrations of H2O2 (200 and 400 μM) decreased protein and mRNA abundance of TXN2, reduced total antioxidant capacity (T-AOC) and ATP content in adipocytes. Moreover, 200 and 400 μM H2O2 reduced protein abundance of inhibitor of kappa B α (IκBα), increased phosphorylation of NF-κB and upregulated mRNA abundance of tumor necrosis factor-α (TNFA) and interleukin-1B (IL-1B), suggesting that H2O2-induced oxidative stress and activated NF-κB signaling pathway. Silencing of TXN2 increased intracellular ROS content, phosphorylation of NF-κB and mRNA abundance of TNFA and IL-1B, decreased ATP content and protein abundance of IκBα in bovine adipocytes. Knockdown of TXN2 aggravated H2O2-induced oxidative stress and inflammation. In addition, treatment with antioxidant NAC ameliorated oxidative stress and inhibited NF-κB signaling pathway in adipocytes transfected with si-TXN2. In bovine adipocytes treated with H2O2, overexpression of TXN2 reduced the content of ROS and elevated the content of ATP and T-AOC. Overexpression of TXN2 alleviated H2O2-induced inflammatory response in adipocytes, as demonstrated by decreased expression of phosphorylated NF-κB, TNFA, IL-1B, as well as increased expression of IκBα. Furthermore, the protein and mRNA abundance of TXN2 was lower in adipose tissue of dairy cows with clinical ketosis. Overall, our studies contribute to the understanding of the role of TXN2 in adipocyte oxidative stress and inflammatory response.

Reactive oxygen species augment contractile responses of saphenous artery in 10-15-day-old but not adult rats: Substantial role of NADPH oxidases

Reactive oxygen species (ROS) produced by NADPH oxidases (NOX, a key source of ROS in vascular cells) are involved in the regulation of vascular tone, but this has been explored mainly for adult organisms. Importantly, the mechanisms of vascular tone regulation differ significantly in early postnatal ontogenesis and adulthood, while the vasomotor role of ROS in immature systemic arteries is poorly understood. We tested the hypothesis that the functional contribution of NADPH oxidase-derived ROS to the regulation of peripheral arterial tone is higher in the early postnatal period than in adulthood. We studied saphenous arteries from 10- to 15-day-old ("young") and 3- to 4-month-old ("adult") male rats using lucigenin-enhanced chemiluminescence, quantitative PCR, Western blotting, and isometric myography. We demonstrated that both basal and NADPH-stimulated superoxide anion radical (O2•-) production was significantly higher in the arteries from young in comparison to adult rats. Importantly, pan-inhibitor of NADPH oxidase VAS2870 (10 μM) reduced NADPH-induced O2•- production in arteries of young rats. Saphenous arteries of both young and adult rats demonstrated high levels of Nox2 and Nox4 mRNAs, while Nox1 and Nox3 mRNAs were not detected. The protein contents of NOX2 and NOX4 were significantly higher in arterial tissue of young compared to adult animals. Moreover, VAS2870 (10 μM) had no effect on methoxamine-induced contractile responses of adult arteries but decreased them significantly in young arteries; such effect of VAS2870 persisted after removal of the endothelium. Finally, NOX2 inhibitor GSK2795039 (10 μM), but not NOX1/4 inhibitor GKT137831 (10 μM) weakened methoxamine-induced contractile responses of arteries from young rats. Thus, ROS produced by NOX2 have a pronounced contractile influence in saphenous artery smooth muscle cells of young, but not adult rats, which is associated with the increased vascular content of NOX2 protein at this age.

Targeting the redox system for cardiovascular regeneration in aging

Cardiovascular aging presents a formidable challenge, as the aging process can lead to reduced cardiac function and heightened susceptibility to cardiovascular diseases. Consequently, there is an escalating, unmet medical need for innovative and effective cardiovascular regeneration strategies aimed at restoring and rejuvenating aging cardiovascular tissues. Altered redox homeostasis and the accumulation of oxidative damage play a pivotal role in detrimental changes to stem cell function and cellular senescence, hampering regenerative capacity in aged cardiovascular system. A mounting body of evidence underscores the significance of targeting redox machinery to restore stem cell self-renewal and enhance their differentiation potential into youthful cardiovascular lineages. Hence, the redox machinery holds promise as a target for optimizing cardiovascular regenerative therapies. In this context, we delve into the current understanding of redox homeostasis in regulating stem cell function and reprogramming processes that impact the regenerative potential of the cardiovascular system. Furthermore, we offer insights into the recent translational and clinical implications of redox-targeting compounds aimed at enhancing current regenerative therapies for aging cardiovascular tissues.

Spatial resolution of cellular senescence dynamics in human colorectal liver metastasis

Hepatic metastasis is a clinical challenge for colorectal cancer (CRC). Senescent cancer cells accumulate in CRC favoring tumor dissemination. Whether this mechanism progresses also in metastasis is unexplored. Here, we integrated spatial transcriptomics, 3D-microscopy, and multicellular transcriptomics to study the role of cellular senescence in human colorectal liver metastasis (CRLM). We discovered two distinct senescent metastatic cancer cell (SMCC) subtypes, transcriptionally located at the opposite pole of epithelial (e) to mesenchymal (m) transition. SMCCs differ in chemotherapy susceptibility, biological program, and prognostic roles. Mechanistically, epithelial (e)SMCC initiation relies on nucleolar stress, whereby c-myc dependent oncogene hyperactivation induces ribosomal RPL11 accumulation and DNA damage response. In a 2D pre-clinical model, we demonstrated that RPL11 co-localized with HDM2, a p53-specific ubiquitin ligase, leading to senescence activation in (e)SMCCs. On the contrary, mesenchymal (m)SMCCs undergo TGFβ paracrine activation of NOX4-p15 effectors. SMCCs display opposing effects also in the immune regulation of neighboring cells, establishing an immunosuppressive environment or leading to an active immune workflow. Both SMCC signatures are predictive biomarkers whose unbalanced ratio determined the clinical outcome in CRLM and CRC patients. Altogether, we provide a comprehensive new understanding of the role of SMCCs in CRLM and highlight their potential as new therapeutic targets to limit CRLM progression.

Diabetic vascular diseases: molecular mechanisms and therapeutic strategies

Vascular complications of diabetes pose a severe threat to human health. Prevention and treatment protocols based on a single vascular complication are no longer suitable for the long-term management of patients with diabetes. Diabetic panvascular disease (DPD) is a clinical syndrome in which vessels of various sizes, including macrovessels and microvessels in the cardiac, cerebral, renal, ophthalmic, and peripheral systems of patients with diabetes, develop atherosclerosis as a common pathology. Pathological manifestations of DPDs usually manifest macrovascular atherosclerosis, as well as microvascular endothelial function impairment, basement membrane thickening, and microthrombosis. Cardiac, cerebral, and peripheral microangiopathy coexist with microangiopathy, while renal and retinal are predominantly microangiopathic. The following associations exist between DPDs: numerous similar molecular mechanisms, and risk-predictive relationships between diseases. Aggressive glycemic control combined with early comprehensive vascular intervention is the key to prevention and treatment. In addition to the widely recommended metformin, glucagon-like peptide-1 agonist, and sodium-glucose cotransporter-2 inhibitors, for the latest molecular mechanisms, aldose reductase inhibitors, peroxisome proliferator-activated receptor-γ agonizts, glucokinases agonizts, mitochondrial energy modulators, etc. are under active development. DPDs are proposed for patients to obtain more systematic clinical care requires a comprehensive diabetes care center focusing on panvascular diseases. This would leverage the advantages of a cross-disciplinary approach to achieve better integration of the pathogenesis and therapeutic evidence. Such a strategy would confer more clinical benefits to patients and promote the comprehensive development of DPD as a discipline.

Decreased Cardiac NOX4 and SIRT-1 Protein Levels Contribute to Decreased Angiogenesis in the Heart of Diabetic Rats: Rescue Effects of IGF-1 and Exercise

Purpose: Reduced angiogenesis in the heart tissue is a primary risk factor for heart disease in the diabetes condition. This study was aimed to evaluate the changes of two main angiogenesis mediators, NADPH oxidase 4 (NOX4) and sirtuin 1 (SIRT-1) protein levels in the heart of diabetic rats and the impact of Insulin-like growth factor 1 (IGF-1) and exercise on these proteins. Methods: Injection of 60 mg/kg of streptozotocin in 40 male Wistar rats led to the induction of type 1 diabetes. Angiogenesis was detected in the hearts by immunostaining for PECAM-1/ CD31 after 30 days of treatment with IGF-1 (2 mg/kg/day) and exercise. ELISA technique was utilized to establish the expression levels of NOX4 and SIRT-1 within the heart. Results: The results revealed a significant increase in HbA1c and a significant decrease in SIRT1, NOX4 levels and angiogenesis grade in the heart of diabetes group compared to control group. Meanwhile, IGF-1 and exercise alone or in combination completely masked these effects. Additionally, synergistic effect on SIRT-1, HbA1c levels and angiogenesis grade is evident when IGF-1 and exercise are applied simultaneously. Conclusion: Our findings suggest that reduction in angiogenesis in the heart of diabetic rats may be mediated by down expression of NOX4 and SIRT-1 protein levels. It was also displayed that IGF-1 and exercise as novel therapies increase NOX4 and SIRT-1 protein levels within the hearts of diabetic rats.

Target RNA expression omics approach to reveal the liver detoxification effect induced by Chinese medicine prescription Niu Huang Jie Du against realgar overexposure to mice

ETHNOPHARMACOLOGICAL RELEVANCE

Niu Huang Jie Du prescription (NHJD) is a traditional Chinese medicine (TCM) widely used in patients suffering from excessive inner fire toxin (Huo Du Nei Sheng) syndrome, such as sore throat, gingival swelling, and pain, mouth and tongue sores, etc. This formula contains realgar (As₄S₄) which is one of the 28 toxic medicinal materials promulgated by the Chinese Ministry of Health. Many studies reported its toxicity on the liver and kidney, and the detoxification effect of NHJD. However, its detoxification mechanism is still unclear.

AIM OF THE STUDY

To clarify the detoxification mechanism of NHJD to realgar, this study evaluated the detoxification effect of NHJD on realgar exposure in mice, and analyzed differences in mRNA expression profiles in liver tissues and associated functional predictions.

MATERIAL AND METHODS

ICR mice were administered with NHJD, realgar, and CMC-Na as blank control for 12 weeks, respectively. Liver injury was evaluated by histopathologic examination and liver mRNA gene were sequenced by Illumina. Differentially expressed gene, functionally enrichment and protein association network analysis were conducted.

RESULTS

43 genes were screened out, among which 15 genes in the realgar group were decreased, but the extent of the decline has been restored in the NHJD group. The remaining 28 genes have exactly the opposite trends. Functional module analysis revealed that those detoxification function-related genes were primarily for positive regulation of glutathione metabolism, P450 on the metabolism of exogenous compounds, oxidative stress and immune-related, etc. CONCLUSIONS: The results indicated that realgar mainly causes liver damage by changing the common enzymes of drug metabolism, especially the expression of genes related to CYPs, GSTs family, oxidative stress, and complement immunity, while the TCM prescription NHJD has a regulatory effect on the abnormal expression of corresponding genes. Our results will provide some clues for the detoxification mechanism of arsenic-containing TCM prescriptions.

Disengaging the COVID-19 Clutch as a Discerning Eye Over the Inflammatory Circuit During SARS-CoV-2 Infection

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes the cytokine release syndrome (CRS) and leads to multiorgan dysfunction. Mitochondrial dynamics are fundamental to protect against environmental insults, but they are highly susceptible to viral infections. Defective mitochondria are potential sources of reactive oxygen species (ROS). Infection with SARS-CoV-2 damages mitochondria, alters autophagy, reduces nitric oxide (NO), and increases both nicotinamide adenine dinucleotide phosphate oxidases (NOX) and ROS. Patients with coronavirus disease 2019 (COVID-19) exhibited activated toll-like receptors (TLRs) and the Nucleotide-binding and oligomerization domain (NOD-), leucine-rich repeat (LRR-), pyrin domain-containing protein 3 (NLRP3) inflammasome. The activation of TLRs and NLRP3 by SARS-CoV-2 induces interleukin 6 (IL-6), IL-1β, IL-18, and lactate dehydrogenase (LDH). Herein, we outline the inflammatory circuit of COVID-19 and what occurs behind the scene, the interplay of NOX/ROS and their role in hypoxia and thrombosis, and the important role of ROS scavengers to reduce COVID-19-related inflammation.

TRX2/Rab35 Interaction Impairs Exosome Secretion by Inducing Rab35 Degradation

Given that exosomes mediate intercellular communication by delivering cellular components to recipient cells or tissue, they have the potential to be engineered to deliver therapeutic payloads. However, the regulatory mechanism of exosome secretion is poorly understood. In addition, mitochondrial components have been found in exosomes, suggesting communication between mitochondria and exosomes. However, the molecular mechanism of the mitochondria and vesicle interaction remains unclear. Here, we showed that mitochondrial thioredoxin 2 (TRX2) decreased exosome concentrations and inhibited HCT116 cell migration. Coimmunoprecipitation/mass spectrometry (Co-IP/MS) showed that TRX2 interacted with Rab35. TRX2 and Rab35 bound to each other at their N-terminal motifs and colocalized on mitochondria. Furthermore, TRX2 induced Rab35 degradation, resulting in impaired exosome secretion. Additionally, Rab35 mediated the suppressive effects of TRX2 on cell migration, and TRX2 suppressed cell migration through exosomes. Taken together, this study first found an interaction between TRX2 and Rab35. These results revealed a new role for TRX2 in the regulation of exosome secretion and cell migration and explained the upstream regulatory mechanism of Rab35. Furthermore, these findings also provide new molecular evidence for communication between mitochondria and vesicles.

Oxidative Stress Is a Key Modulator in the Development of Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease worldwide, and scientific studies consistently report that NAFLD development can be accelerated by oxidative stress. Oxidative stress can induce the progression of NAFLD to NASH by stimulating Kupffer cells, hepatic stellate cells, and hepatocytes. Therefore, studies are underway to identify the role of antioxidants in the treatment of NAFLD. In this review, we have summarized the origins of reactive oxygen species (ROS) in cells, the relationship between ROS and NAFLD, and have discussed the use of antioxidants as therapeutic agents for NAFLD.

Phototoxicity-free blue light for enhancing therapeutic angiogenic efficacy of stem cells

Low-level light therapy (LLLT) is a safe and noninvasive technique that has drawn attention as a new therapeutic method to treat various diseases. However, little is known so far about the effect of blue light for LLLT due to the generation of reactive oxygen species (ROS) that can cause cell damage. We introduced a blue organic light-emitting diode (bOLED) as a safe and effective light source that could generate a low amount of heat and luminance compared to conventional light sources (e.g., light-emitting diodes). We compared phototoxicity of bOLED light with different light fluences to human adipose-derived stem cells (hADSC). We further explored molecular mechanisms involved in the therapeutic efficacy of bOLED for enhancing angiogenic properties of hADSC, including intracellular ROS control in hADSCs. Using optimum conditions of bOLED light proposed in this study, photobiomodulation and angiogenic properties of hADSCs were enhanced. These findings might open new methods for using blue light in LLLT. Such methods can be implemented in future treatments for ischemic disease.

Behind the Adaptive and Resistance Mechanisms of Cancer Stem Cells to TRAIL

Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL), also known as Apo-2 ligand (Apo2L), is a member of the TNF cytokine superfamily. TRAIL has been widely studied as a novel strategy for tumor elimination, as cancer cells overexpress TRAIL death receptors, inducing apoptosis and inhibiting blood vessel formation. However, cancer stem cells (CSCs), which are the main culprits responsible for therapy resistance and cancer remission, can easily develop evasion mechanisms for TRAIL apoptosis. By further modifying their properties, they take advantage of this molecule to improve survival and angiogenesis. The molecular mechanisms that CSCs use for TRAIL resistance and angiogenesis development are not well elucidated. Recent research has shown that proteins and transcription factors from the cell cycle, survival, and invasion pathways are involved. This review summarizes the main mechanism of cell adaption by TRAIL to promote response angiogenic or pro-angiogenic intermediates that facilitate TRAIL resistance regulation and cancer progression by CSCs and novel strategies to induce apoptosis.

Behind the Adaptive and Resistance Mechanisms of Cancer Stem Cells to TRAIL

Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL), also known as Apo-2 ligand (Apo2L), is a member of the TNF cytokine superfamily. TRAIL has been widely studied as a novel strategy for tumor elimination, as cancer cells overexpress TRAIL death receptors, inducing apoptosis and inhibiting blood vessel formation. However, cancer stem cells (CSCs), which are the main culprits responsible for therapy resistance and cancer remission, can easily develop evasion mechanisms for TRAIL apoptosis. By further modifying their properties, they take advantage of this molecule to improve survival and angiogenesis. The molecular mechanisms that CSCs use for TRAIL resistance and angiogenesis development are not well elucidated. Recent research has shown that proteins and transcription factors from the cell cycle, survival, and invasion pathways are involved. This review summarizes the main mechanism of cell adaption by TRAIL to promote response angiogenic or pro-angiogenic intermediates that facilitate TRAIL resistance regulation and cancer progression by CSCs and novel strategies to induce apoptosis.

Regulation of redox signaling in HIF-1-dependent tumor angiogenesis

Angiogenesis is the process of blood vessel growth. The angiogenic switch consists of new blood vessel formation that, in carcinogenesis, can lead to the transition from a harmless cluster of dormant cells to a large tumorigenic mass with metastatic potential. Hypoxia, that is, the scarcity of oxygen, is a hallmark of solid tumors to which they adapt by activating hypoxia-inducible factor-1 (HIF-1), a transcription factor triggering de novo angiogenesis. HIF-1 and the angiogenic molecules that are expressed upon its activation are modulated by redox status. Modulations of the redox environment can influence the angiogenesis signaling at different levels, thereby impinging on the angiogenic switch. This review provides a molecular overview of the redox-sensitive steps in angiogenic signaling, the main molecular players involved, and their crosstalk with the unfolded protein response. New classes of inhibitors of these modulators which might act as antiangiogenic drugs in cancer are also discussed.

Pleiotropic and Potentially Beneficial Effects of Reactive Oxygen Species on the Intracellular Signaling Pathways in Endothelial Cells

Endothelial cells (ECs) are exposed to molecular dioxygen and its derivative reactive oxygen species (ROS). ROS are now well established as important signaling messengers. Excessive production of ROS, however, results in oxidative stress, a significant contributor to the development of numerous diseases. Here, we analyze the experimental data and theoretical concepts concerning positive pro-survival effects of ROS on signaling pathways in endothelial cells (ECs). Our analysis of the available experimental data suggests possible positive roles of ROS in induction of pro-survival pathways, downstream of the G_i-protein-coupled receptors, which mimics insulin signaling and prevention or improvement of the endothelial dysfunction. It is, however, doubtful, whether ROS can contribute to the stabilization of the endothelial barrier.

Characterization of NADPH Oxidase Expression and Activity in Acute Myeloid Leukemia Cell Lines: A Correlation with the Differentiation Status

In acute myeloid leukemia (AML), a low level of reactive oxygen species (ROS) is associated with leukemic stem cell (LSC) quiescence, whereas a high level promotes blast proliferation. ROS homeostasis relies on a tightly-regulated balance between the antioxidant and oxidant systems. Among the oxidants, NADPH oxidases (NOX) generate ROS as a physiological function. Although it has been reported in AML initiation and development, the contribution of NOX to the ROS production in AML remains to be clarified. The aim of this study was to investigate the NOX expression and function in AML, and to examine the role of NOX in blast proliferation and differentiation. First, we interrogated the NOX expression in primary cells from public datasets, and investigated their association with prognostic markers. Next, we explored the NOX expression and activity in AML cell lines, and studied the impact of NOX knockdown on cell proliferation and differentiation. We found that NOX2 is ubiquitously expressed in AML blasts, and particularly in cells from the myelomonocytic (M4) and monocytic (M5) stages; however, it is less expressed in LSCs and in relapsed AML. This is consistent with an increased expression throughout normal hematopoietic differentiation, and is reflected in AML cell lines. Nevertheless, no endogenous NOX activity could be detected in the absence of PMA stimulation. Furthermore, CYBB knockdown, although hampering induced NOX2 activity, did not affect the proliferation and differentiation of THP-1 and HL-60 cells. In summary, our data suggest that NOX2 is a marker of AML blast differentiation, while AML cell lines lack any NOX2 endogenous activity.

Pan-Cancer Analysis Shows TP53 Mutations Modulate the Association of NOX4 with Genetic Programs of Cancer Progression and Clinical Outcome

Previously, we have shown TGF-β-induced NOX4 expression is involved in the epithelial-to-mesenchymal transition (EMT), a process critical for cancer metastasis, and that wild-type (WT) and mutant (Mut) p53 have divergent effects on TGF-β induction of NOX4: WT-p53 suppresses whereas Mut-p53 augments NOX4 mRNA and protein production in several tumor cell models. We sought to validate and extend our model by analyzing whole-exome data of primary tumor samples in The Cancer Genome Atlas (TCGA). We constructed a Pan-Cancer dataset from 23 tumor types and explored NOX4 expression patterns in relation to EMT and patient survival. NOX4 mRNA levels increase as a function of cancer progression in several cancers and correlate with Mut-p53 mRNA and genes involved in programs of EMT, cellular adhesion, migration, and angiogenesis. Tumor macrophages appear to be a source of NOX2, whose association with genetic programs of cancer progression emulate that of NOX4. Notably, increased NOX4 expression is linked to poorer survival in patients with Mut-TP53, but better survival in patients with WT-TP53. NOX4 is negatively associated with markers of apoptosis and positively with markers of proliferation in patients with Mut-TP53, consistent with their poorer survival. These findings suggest that TP53 mutations could “switch” NOX4 from being protective and an indicator of good prognosis to deleterious by promoting programs favoring cancer progression.

Immunomodulatory role of reactive oxygen species and nitrogen species during T cell-driven neutrophil-enriched acute and chronic cutaneous delayed-type hypersensitivity reactions

Rationale: Reactive oxygen species (ROS) and reactive nitrogen species (RNS) are important regulators of inflammation. The exact impact of ROS/RNS on cutaneous delayed-type hypersensitivity reaction (DTHR) is controversial. The aim of our study was to identify the dominant sources of ROS/RNS during acute and chronic trinitrochlorobenzene (TNCB)-induced cutaneous DTHR in mice with differently impaired ROS/RNS production. Methods: TNCB-sensitized wild-type, NADPH oxidase 2 (NOX2)- deficient (gp91^phox-/-), myeloperoxidase-deficient (MPO^-/-), and inducible nitric oxide synthase-deficient (iNOS^-/-) mice were challenged with TNCB on the right ear once to elicit acute DTHR and repetitively up to five times to induce chronic DTHR. We measured ear swelling responses and noninvasively assessed ROS/RNS production in vivo by employing the chemiluminescence optical imaging (OI) probe L-012. Additionally, we conducted extensive ex vivo analyses of inflamed ears focusing on ROS/RNS production and the biochemical and morphological consequences. Results: The in vivo L-012 OI of acute and chronic DTHR revealed completely abrogated ROS/RNS production in the ears of gp91^phox-/- mice, up to 90 % decreased ROS/RNS production in the ears of MPO^-/- mice and unaffected ROS/RNS production in the ears of iNOS^-/- mice. The DHR flow cytometry analysis of leukocytes derived from the ears with acute DTHR confirmed our in vivo L-012 OI results. Nevertheless, we observed no significant differences in the ear swelling responses among all the experimental groups. The histopathological analysis of the ears of gp91^phox-/- mice with acute DTHRs revealed slightly enhanced inflammation. In contrast, we observed a moderately reduced inflammatory immune response in the ears of gp91^phox-/- mice with chronic DTHR, while the inflamed ears of MPO^-/- mice exhibited the strongest inflammation. Analyses of lipid peroxidation, 8-hydroxy-2'deoxyguanosine levels, redox related metabolites and genomic expression of antioxidant proteins revealed similar oxidative stress in all experimental groups. Furthermore, inflamed ears of wild-type and gp91^phox-/- mice displayed neutrophil extracellular trap (NET) formation exclusively in acute but not chronic DTHR. Conclusions: MPO and NOX2 are the dominant sources of ROS/RNS in acute and chronic DTHR. Nevertheless, depletion of one primary source of ROS/RNS exhibited only marginal but conflicting impact on acute and chronic cutaneous DTHR. Thus, ROS/RNS are not a single entity, and each species has different properties at certain stages of the disease, resulting in different outcomes.

Inhibiting the Activity of NADPH Oxidase in Cancer

Significance: The primary function of NADPH oxidases (NOX1-5 and dual oxidases DUOX1/2) is to produce reactive oxygen species (ROS). If inadequately regulated, NOX-associated ROS can promote oxidative stress, aberrant signaling, and genomic instability. Correspondingly, NOX isoforms are known to be overexpressed in multiple malignancies, thus constituting potential therapeutic targets in cancer. Recent Advances: Multiple genetic studies aimed at suppressing the expression of NOX proteins in cellular and animal models of cancer have provided support for the notion that NOXs play a pro-tumorigenic role. Further, large drug screens and rational design efforts have yielded inhibitor compounds, such as the diphenylene iodonium (DPI) analog series developed by our group, with increased selectivity and potency over "first generation" NOX inhibitors such as apocynin and DPI. Critical Issues: The precise role of NOX enzymes in tumor biology remains poorly defined. The tumorigenic properties of NOXs vary with cancer type, and precise tools, such as selective inhibitors, are needed to deconvolute NOX contribution to cancer development. Most NOX inhibitors developed to date are unspecific, and/or their mechanistic and pharmacological characteristics are not well defined. A lack of high-resolution crystal structures for NOX functional domains has hindered the development of potent and selective inhibitors. Future Directions: In-depth studies of NOX interactions with the tumor microenvironment (e.g., cytokines, cell-surface antigens) will help identify new approaches for NOX inhibition in cancer.

The role of NOX4 in pulmonary diseases

Nicotinamide adenine dinucleotide phosphate oxidase 4 (NOX4) is a subtype of the NOX family, which is mainly expressed in the pulmonary vasculature and pulmonary endothelial cells in the respiratory system. NOX4 has unique characteristics, and is a constitutively active enzyme that primarily produces hydrogen peroxide. The signaling pathways associated with NOX4 are complicated. Negative and positive feedback play significant roles in regulating NOX4 expression. The role of NOX4 is controversial because NOX4 plays a protective or damaging role in different respiratory diseases. This review summarizes the structure, enzymatic properties, regulation, and signaling pathways of NOX4. This review then introduces the roles of NOX4 in different diseases in the respiratory system, such as acute respiratory distress syndrome, chronic obstructive pulmonary disease, and pulmonary fibrosis.

Redox basis of exercise physiology

Redox reactions control fundamental processes of human biology. Therefore, it is safe to assume that the responses and adaptations to exercise are, at least in part, mediated by redox reactions. In this review, we are trying to show that redox reactions are the basis of exercise physiology by outlining the redox signaling pathways that regulate four characteristic acute exercise-induced responses (muscle contractile function, glucose uptake, blood flow and bioenergetics) and four chronic exercise-induced adaptations (mitochondrial biogenesis, muscle hypertrophy, angiogenesis and redox homeostasis). Based on our analysis, we argue that redox regulation should be acknowledged as central to exercise physiology.

A Unique SUMO-Interacting Motif of Trx2 Is Critical for Its Mitochondrial Presequence Processing and Anti-oxidant Activity

OBJECTIVE

Mitochondrial thioredoxin 2 (Trx2) is a vital mitochondrial redox protein that mediates normal protein thiol reduction and provides electrons to peroxiredoxin 3 (Prx3) to scavenge H2O2 in mitochondria. It has been widely reported that Trx2 deletion in cells or mice generates massive reactive oxygen species (ROS) which have been implicated in many pathological processes. On the contrary, how ROS regulate Trx2 processing and activity remains to be elucidated.

APPROACH AND RESULTS

Here we show that excess ROS induce endothelial cell senescence concomitant with an attenuation of Trx2 processing in which Trx2 presequence [i.e., mitochondrial targeting signal peptide (MTS)] is cleaved to generate a mature form. Mutation analyses indicate that Trx2 processing is mediated by mitochondrial processing peptidase (MPP) and mitochondrial intermediate peptidase (MIP)-recognition sites within the MTS. Interestingly, a mutation at a SUMO- interacting motif (SIM), but not the catalytic sites within the mature Trx2 protein, completely blocks Trx2 processing with no effect on Trx2 mitochondrial targeting. Consistently, chemical inhibition of protein SUMOylation attenuates, while SUMOylation agonist promotes, Trx2 processing. Moreover, we identify the α-MPP subunit is a SUMOylated protein that potentially mediates Trx2-binding and cleavage. Furthermore, the unprocessed form of Trx2-SIM is unable to protect cells from both ROS generation and oxidative stress-induced cellular senescence.

CONCLUSION

Our study reveals that a unique SUMO-interacting motif of Trx2 is critical for its mitochondrial processing and subsequent anti-oxidant/antisenescence activities.

Preparation of Titanocene-Gold Compounds Based on Highly Active Gold(I)-N-Heterocyclic Carbene Anticancer Agents: Preliminary in vitro Studies in Renal and Prostate Cancer Cell Lines

Heterometallic titanocene-based compounds containing gold(I)-phosphane fragments have been extremely successful against renal cancer in vitro and in vivo. The exchange of phosphane by N-heterocyclic carbene ligands to improve or modulate their pharmacological profile afforded bimetallic complexes effective against prostate cancer, but less effective against renal cancer in vitro. Herein we report the synthesis of new bimetallic Ti-Au compounds by the incorporation of two previously reported highly active gold(I)-N-heterocyclic carbene fragments derived from 4,5-diarylimidazoles. The two new compounds [(η5 -C5 H5 )2 TiMe(μ-mba)Au(NHC)] (where NHC=1,3-dibenzyl-4,5-diphenylimidazol-2-ylidene, NHC-Bn 2 a; or 1,3-diethyl-4,5-diphenylimidazol-2-ylidene, NHC-Et 2 b) with the dual linker (-OC(O)-p-C6 H4 -S-) containing both a carboxylate and a thiolate group were evaluated in vitro against renal and prostate cancer cell lines. The compounds were found to be more cytotoxic than previously described Ti-Au compounds containing non-optimized gold(I)-N-heterocyclic fragments. We present studies to evaluate their effects on cell death pathways, migration, inhibition of thioredoxin reductase (TrxR) and vascular endothelial growth factor (VEGF) in the PC3 prostate cancer cell line. The results show that the incorporation of a second metallic fragment such as titanocene into biologically active gold(I) compounds improves their pharmacological profile.

Tubular NOX4 expression decreases in chronic kidney disease but does not modify fibrosis evolution

Background

NADPH oxidase 4 (NOX4) catalyzes the formation of hydrogen peroxide (H₂O₂). NOX4 is highly expressed in the kidney, but its role in renal injury is unclear and may depend on its specific tissue localization.

Methods

We performed immunostaining with a specific anti-NOX4 antibody and measured NOX4 mRNA expression in human renal biopsies encompassing diverse renal diseases. We generated transgenic mice specifically overexpressing mouse Nox4 in renal tubular cells and subjected the animals to the unilateral ureteral obstruction (UUO) model of fibrosis.

Results

In normal human kidney, NOX4 protein expression was at its highest on the basolateral side of proximal tubular cells. NOX4 expression increased in mesangial cells and podocytes in proliferative diabetic nephropathy. In tubular cells, NOX4 protein expression decreased in all types of chronic renal disease studied. This finding was substantiated by decreased NOX4 mRNA expression in the tubulo-interstitial compartment in a repository of 175 human renal biopsies. Overexpression of tubular NOX4 in mice resulted in enhanced renal production of H₂O₂, increased NRF2 protein expression and decreased glomerular filtration, likely via stimulation of the tubulo-glomerular feedback. Tubular NOX4 overexpression had no obvious impact on kidney morphology, apoptosis, or fibrosis at baseline. Under acute and chronic tubular injury induced by UUO, overexpression of NOX4 in tubular cells did not modify the course of the disease.

Conclusions

NOX4 expression was decreased in tubular cells in all types of CKD tested. Tubular NOX4 overexpression did not induce injury in the kidney, and neither modified microvascularization, nor kidney structural lesions in fibrosis.

Possible Molecular Mediators Involved and Mechanistic Insight into Fibromyalgia and Associated Co-morbidities

Fibromyalgia is a chronic complex syndrome of non-articulate origin characterized by musculoskeletal pain, painful tender points, sleep problems and co-morbidities including depression, migraine. The etiopathogenesis of fibromyalgia is complex, variable and remains inconclusive. The etiological factors that have been defined include stress, genetic predisposition and environmental components. As per the reports of the American College of Rheumatology (ACR) the prevalence of fibromyalgia varies from 2 to 22% among the general population with poor diagnostic features primarily pain. Fibromyalgia encompasses a spectrum of co-morbid conditions with multifarious pathogenesis. The highly prevalent manifestations of fibromyalgia include heterogeneous pain and aches. Biochemical and neurobiological elements of fibromyalgia include neurotransmitters, hypothalamic pituitary adrenal axis (HPA axis), inflammatory cytokines, monoaminergic pathway, opioid peptides, sex hormones, nerve growth factor (NGF) and local free radical insult. An imbalance in the serotonergic system is the major underlying etiological factor that has been explored most widely. Owing to complex interplay of diverse pathophysiological pathways, overlapping co-morbidities such as depression have been clinically observed. Therapeutic management of fibromyalgia involves both non pharmacological and pharmacological measures. The current review presents various dysregulations and their association with symptoms of fibromyalgia along with their underlying neurobiological aspects.

Neuroprotective mechanisms of dieckol against glutamate toxicity through reactive oxygen species scavenging and nuclear factor-like 2/heme oxygenase-1 pathway

Glutamate toxicity-mediated mitochondrial dysfunction and neuronal cell death are involved in the pathogenesis of several neurodegenerative diseases as well as acute brain ischemia/stroke. In this study, we investigated the neuroprotective mechanism of dieckol (DEK), one of the phlorotannins isolated from the marine brown alga Ecklonia cava, against glutamate toxicity. Primary cortical neurons (100 µM, 24 h) and HT22 neurons (5 mM, 12 h) were stimulated with glutamate to induce glutamate toxic condition. The results demonstrated that DEK treatment significantly increased cell viability in a dose-dependent manner (1–50 µM) and recovered morphological deterioration in glutamate-stimulated neurons. In addition, DEK strongly attenuated intracellular reactive oxygen species (ROS) levels, mitochondrial overload of Ca²⁺ and ROS, mitochondrial membrane potential (ΔΨ_m) disruption, adenine triphosphate depletion. DEK showed free radical scavenging activity in the cell-free system. Furthermore, DEK enhanced protein expression of heme oxygenase-1 (HO-1), an important anti-oxidant enzyme, via the nuclear translocation of nuclear factor-like 2 (Nrf2). Taken together, we conclude that DEK exerts neuroprotective activities against glutamate toxicity through its direct free radical scavenging property and the Nrf-2/HO-1 pathway activation.

Cyclopamine tartrate, a modulator of hedgehog signaling and mitochondrial respiration, effectively arrests lung tumor growth and progression

Lung cancer remains the leading cause of cancer-related death, despite the advent of targeted therapies and immunotherapies. Therefore, it is crucial to identify novel molecular features unique to lung tumors. Here, we show that cyclopamine tartrate (CycT) strongly suppresses the growth of subcutaneously implanted non-small cell lung cancer (NSCLC) xenografts and nearly eradicated orthotopically implanted NSCLC xenografts. CycT reduces heme synthesis and degradation in NSCLC cells and suppresses oxygen consumption in purified mitochondria. In orthotopic tumors, CycT decreases the levels of proteins and enzymes crucial for heme synthesis, uptake, and oxidative phosphorylation (OXPHOS). CycT also decreases the levels of two regulators promoting OXPHOS, MYC and MCL1, and effectively alleviates tumor hypoxia. Evidently, CycT acts via multiple modes to suppress OXPHOS. One mode is to directly inhibit mitochondrial respiration/OXPHOS. Another mode is to inhibit heme synthesis and degradation. Both modes appear to be independent of hedgehog signaling. Addition of heme to NSCLC cells partially reverses the effect of CycT on oxygen consumption, proliferation, and tumorigenic functions. Together, our results strongly suggest that CycT suppress tumor growth in the lung by inhibiting heme metabolism and OXPHOS. Targeting heme metabolism and OXPHOS may be an effective strategy to combat lung cancer.

Holistic Regulation of Angiogenesis with Chinese Herbal Medicines as a New Option for Coronary Artery Disease

Effectively improving myocardial blood flow and controlling atherosclerotic plaque have always been key and difficult points in the prevention and treatment of coronary artery disease (CAD). Although “therapeutic angiogenesis” is regarded as a promising approach for ischemic heart disease by improving blood flow, angiogenesis itself can induce the destabilization of atherosclerotic plaque, which reflects the double-edged role of angiogenesis. Modulating the balance of angiogenesis can be an important target for CAD treatment. Traditional Chinese medicine (TCM) emphasizes the holistic view and dynamic balance of the body. Furthermore, the principle of activating blood circulation and removing blood stasis (ABCRS) is closely connected with angiogenesis and CAD. Recent research suggests that Chinese herbal medicines for ABCRS are effective in balancing the regulation of angiogenesis. This review presents the progress of recent research on the angiogenesis regulation with Chinese herbal medicines for ABCRS in CAD. Moreover, this review demonstrates that Chinese herbal medicines for ABCRS can not only promote angiogenesis in the ischemic area to improve myocardial blood flow but also alleviate angiogenesis to stabilize plaque in atherosclerosis, which reflects the holistic regulatory role in CAD treatment.

Antimicrobial actions of dual oxidases and lactoperoxidase

The NOX/DUOX family of NADPH oxidases are transmembrane proteins generating reactive oxygen species as their primary enzymatic products. NADPH oxidase (NOX) 1-5 and Dual oxidase (DUOX) 1 and 2 are members of this family. These enzymes have several biological functions including immune defense, hormone biosynthesis, fertilization, cell proliferation and differentiation, extracellular matrix formation and vascular regulation. They are found in a variety of tissues such as the airways, salivary glands, colon, thyroid gland and lymphoid organs. The discovery of NADPH oxidases has drastically transformed our view of the biology of reactive oxygen species and oxidative stress. Roles of several isoforms including DUOX1 and DUOX2 in host innate immune defense have been implicated and are still being uncovered. DUOX enzymes highly expressed in the respiratory and salivary gland epithelium have been proposed as the major sources of hydrogen peroxide supporting mucosal oxidative antimicrobial defenses. In this review, we shortly present data on DUOX discovery, structure and function, and provide a detailed, up-to-date summary of discoveries regarding antibacterial, antiviral, antifungal, and antiparasitic functions of DUOX enzymes. We also present all the literature describing the immune functions of lactoperoxidase, an enzyme working in partnership with DUOX to produce antimicrobial substances.