Nitric oxide stimulates heme oxygenase-1 gene transcription via the Nrf2/ARE complex to promote vascular smooth muscle cell survival

Electrochemical Detection of Gasotransmitters: Status and Roadmap

Gasotransmitters, including nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H2S), are a class of gaseous, endogenous signaling molecules that interact with one another in the regulation of critical cardiovascular, immune, and neurological processes. The development of analytical sensing mechanisms for gasotransmitters, especially multianalyte mechanisms, holds vast importance and constitutes a growing area of study. This review provides an overview of electrochemical sensing mechanisms with an emphasis on opportunities in multianalyte sensing. Electrochemical methods demonstrate good sensitivity, adequate selectivity, and the most well-developed potential for the multianalyte detection of gasotransmitters. Future research will likely address challenges with sensor stability and biocompatibility (i.e., sensor lifetime and cytotoxicity), sensor miniaturization, and multianalyte detection in biological settings.

Bisdemethoxycurcumin, a curcumin, protects chondrocytes, and reduces cartilage inflammation via the NRF2/HO-1/NLRP3 pathway

BACKGROUND

The objective of this thesis is to evaluate the effect of bisdemethoxycurcumin (BDMC) on osteoarthritis (OA) and comprehensively evaluate the role of the Nuclear Factor erythroid 2-Related Factor 2 (Nrf2) signalling pathway in chondrocytes.

METHOD

In our study, we treated chondrocytes with BDMC in an in vitro chondrocyte assay and measured its influence on extracellular matrix (ECM) expression, downstream heme oxygenase-1 (HO-1) and NOD-like receptor thermal protein domain associated protein 3 (NLRP3) levels.

RESULTS

Our study indicates that BDMC significantly activates the Nrf2 signaling pathway in chondrocytes in vitro. Furthermore, the expression of matrix metalloproteinase 3, interleukin 1β, recombinant a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS)4 and (ADAMTS)5 was significantly suppressed by BDMC.

CONCLUSION

This study confirms the potential for BDMC to activate the Nrf2/HO-1/NLRP3 signalling pathway and alleviate OA symptoms. Therefore, BDMC is a promising therapeutic agent for OA that offers new insights and treatment methods.

Nitric Oxide Affects Heme Oxygenase-1, Hepcidin, and Transferrin Receptor Expression in the Placenta

Nitric oxide (NO) is a gasotransmitter that avidly binds both free and heme-bound iron, forming relatively stable iron nitrosyl compounds (FeNOs). We have previously demonstrated that FeNOs are present in the human placenta and are elevated in preeclampsia and intrauterine growth restriction. The ability of NO to sequester iron raises the possibility of the NO-mediated disruption of iron homeostasis in the placenta. In this work, we tested whether exposure of placental syncytiotrophoblasts or villous tissue explants to sub-cytotoxic concentrations of NO would elicit the formation of FeNOs. Furthermore, we measured changes in the mRNA and protein expression levels of key iron regulatory genes in response to NO exposure. Ozone-based chemiluminescence was used to measure concentrations of NO and its metabolites. Our results showed a significant increase in FeNO levels in placental cells and explants treated with NO (p < 0.0001). The mRNA and protein levels of HO-1 were significantly increased in both cultured syncytiotrophoblasts and villous tissue explants (p < 0.01), and the mRNA levels of hepcidin and transferrin receptor were significantly increased in culture syncytiotrophoblasts and villous tissue explants, respectively, (p < 0.01), while no changes were seen in the expression levels of divalent metal transporter-1 or ferroportin. These results suggest a potential role for NO in iron homeostasis in the human placenta and could be relevant for disorders of pregnancy such as fetal growth restriction and preeclampsia.

Local delivery of gaseous signaling molecules for orthopedic disease therapy

Over the past decade, a proliferation of research has used nanoparticles to deliver gaseous signaling molecules for medical purposes. The discovery and revelation of the role of gaseous signaling molecules have been accompanied by nanoparticle therapies for their local delivery. While most of them have been applied in oncology, recent advances have demonstrated their considerable potential in diagnosing and treating orthopedic diseases. Three of the currently recognized gaseous signaling molecules, nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H₂S), are highlighted in this review along with their distinctive biological functions and roles in orthopedic diseases. Moreover, this review summarizes the progress in therapeutic development over the past ten years with a deeper discussion of unresolved issues and potential clinical applications.

NO, CO and H2S: A Trinacrium of Bioactive Gases in the Brain

Oxygen and carbon dioxide are time honored gases that have direct bearing on almost all life forms, but over the past thirty years, and in large part due to the Nobel Prize Award in Medicine for the elucidation of nitric oxide (NO) as a bioactive gas, the research and medical communities now recognize other gases as critical for survival. In addition to NO, hydrogen sulfide (H₂S) and carbon monoxide (CO) have emerged as a triumvirate or Trinacrium of gases with analogous importance and that serve important homeostatic functions. Perhaps, one of the most intriguing aspects of these gases is the functional interaction between them, which is intimately linked by the enzyme systems that produce them. Despite the need to better understand NO, H₂S and CO biology, the notion that these are environmental pollutants remains ever present. For this reason, incorporating the concept of hormesis becomes imperative and must be included in discussions when considering developing new therapeutics that involve these gases. While there is now an enormous literature base for each of these gasotransmitters, we provide here an overview of their respective physiologic roles in the brain.

Carbon monoxide signaling and soluble guanylyl cyclase: Facts, myths, and intriguing possibilities

The endogenous signaling roles of carbon monoxide (CO) have been firmly established at the pathway level. For CO's molecular mechanism(s) of actions, hemoproteins are generally considered as possible targets. Importantly, soluble guanylyl cyclase (sGC) is among the most widely referenced molecular targets. However, the affinity of CO for sGC (K_d: 240 μM) is much lower than for other highly abundant hemoproteins in the body, such as myoglobin (K_d: 29 nM) and hemoglobin (K_d: 0.7 nM-4.5 μM), which serve as CO reservoirs. Further, most of the mechanistic studies involving sGC activation by CO were based on in-vitro or ex-vivo studies using CO concentrations not readily attenable in vivo and in the absence of hemoglobin as a competitor in binding. As such, whether such in-vitro/ex-vivo results can be directly extrapolated to in-vivo studies is not clear because of the need for CO to be transferred from a high-affinity binder (e.g., hemoglobin) to a low-affinity target if sGC is to be activated in vivo. In this review, we discuss literature findings of sGC activation by CO and the experimental conditions; examine the myths in the disconnect between the low affinity of sGC for CO and the reported activation of sGC by CO; and finally present several possibilities that may lead to additional studies to improve our understanding of this direct CO-sGC axis, which is yet to be convincingly established as playing generally critical roles in CO signaling in vivo.

Phenotypic Modulation of Macrophages and Vascular Smooth Muscle Cells in Atherosclerosis-Nitro-Redox Interconnections

Monocytes/macrophages and vascular smooth muscle cells (vSMCs) are the main cell types implicated in atherosclerosis development, and unlike other mature cell types, both retain a remarkable plasticity. In mature vessels, differentiated vSMCs control the vascular tone and the blood pressure. In response to vascular injury and modifications of the local environment (inflammation, oxidative stress), vSMCs switch from a contractile to a secretory phenotype and also display macrophagic markers expression and a macrophagic behaviour. Endothelial dysfunction promotes adhesion to the endothelium of monocytes, which infiltrate the sub-endothelium and differentiate into macrophages. The latter become polarised into M1 (pro-inflammatory), M2 (anti-inflammatory) or Mox macrophages (oxidative stress phenotype). Both monocyte-derived macrophages and macrophage-like vSMCs are able to internalise and accumulate oxLDL, leading to formation of “foam cells” within atherosclerotic plaques. Variations in the levels of nitric oxide (NO) can affect several of the molecular pathways implicated in the described phenomena. Elucidation of the underlying mechanisms could help to identify novel specific therapeutic targets, but to date much remains to be explored. The present article is an overview of the different factors and signalling pathways implicated in plaque formation and of the effects of NO on the molecular steps of the phenotypic switch of macrophages and vSMCs.

Dim Light at Night Impairs Daily Variation of Circulating Immune Cells and Renal Immune Homeostasis

Dim light at night (dLAN) has become a pervasive part of the modern world, and growing evidence shows its association with increased health risks. Though this link is attributed to a disturbed circadian clock, the underlying mechanisms that can explain how circadian disruption from dLAN causes negative health effects remain unclear. Here, we exposed rats to a light–dark cycle (12:12 h) with low-intensity light at night (~2 lx) for 2 and 5 weeks and explored the steady-state pattern of circulating immune cells and renal immune-related markers, which are well controlled by the circadian clock. After 5 weeks, dLAN impaired the daily variation in several types of white blood cells, especially monocytes and T cells. Two-week dLAN caused a reduction in blood monocytes and altered gene expression of macrophage marker Cd68 and monocyte-attracting chemokine Ccl2 in the kidney. Interestingly, dLAN decreased renal 3-nitrotyrosine levels and resulted in up-regulation of the main endogenous antioxidant pathways, indicating a disturbance in the renal redox balance and an activation of compensatory mechanisms. These effects paralleled the altered renal expression of the molecular clock components and increased plasma corticosterone levels. Together, our results show that chronic exposure to dLAN weakened the circadian control of daily variation of circulating immune cells and disturbed renal immune and redox homeostasis. Consequences of this dLAN-disturbed immune balance on the ability of the immune system to cope with other challenges should by clarified in further studies.

Heme Oxygenase-1 in Gastrointestinal Tract Health and Disease

Heme oxygenase 1 (HO-1) is the rate-limiting enzyme of heme oxidative degradation, generating carbon monoxide (CO), free iron, and biliverdin. HO-1, a stress inducible enzyme, is considered as an anti-oxidative and cytoprotective agent. As many studies suggest, HO-1 is highly expressed in the gastrointestinal tract where it is involved in the response to inflammatory processes, which may lead to several diseases such as pancreatitis, diabetes, fatty liver disease, inflammatory bowel disease, and cancer. In this review, we highlight the pivotal role of HO-1 and its downstream effectors in the development of disorders and their beneficial effects on the maintenance of the gastrointestinal tract health. We also examine clinical trials involving the therapeutic targets derived from HO-1 system for the most common diseases of the digestive system.

Gasotransmitter synthesis and signalling in the renal glomerulus. Implications for glomerular diseases

Glomerular injury is a hallmark of kidney diseases such as diabetic nephropathy, IgA nephropathy or other forms of glomerulonephritis. Glomerular endothelial cells, mesangial cells, glomerular epithelial cells (podocytes) and, in an inflammatory context, infiltrating immune cells crosstalk to mediate signalling processes in the glomerulus. Under physiological conditions, mesangial cells act by the control of extracellular matrix production and degradation, by the synthesis of growth factors and by preserving a well-defined crosstalk with glomerular podocytes and endothelial cells to regulate glomerular structure and function. It is well known that mesangial cells are able to amplify an inflammatory process by the formation of cytokines, reactive oxygen species (ROS) and nitric oxide (NO). This exaggerated reaction may result in a vicious cycle with subsequent damage of neighboured podocytes and endothelial cells, loss of the filtration barrier and, finally destruction of the whole glomerulus. Unfortunately, all efforts to develop new therapies for the treatment of glomerular diseases by controlling unbridled ROS or NO production directly had so far no success. However, on-going research on ROS and NO defined these autacoids more as important signalling molecules than as endogenously produced cytotoxic compounds. New findings on signalling activities of ROS, NO but also hydrogen sulfide (H₂S) and carbon monoxide (CO) supported this paradigm shift. Because of their similar chemical properties and their similar signal transduction capacities, NO, H₂S and CO are meanwhile designated as the group of gasotransmitters. In this review, we describe the current knowledge of the signalling properties of gasotransmitters with a focus on glomerular cells and their role in glomerular diseases.

Nitric Oxide in Macrophage Immunometabolism: Hiding in Plain Sight

Nitric Oxide (NO) is a soluble endogenous gas with various biological functions like signaling, and working as an effector molecule or metabolic regulator. In response to inflammatory signals, immune myeloid cells, like macrophages, increase production of cytokines and NO, which is important for pathogen killing. Under these proinflammatory circumstances, called “M1”, macrophages undergo a series of metabolic changes including rewiring of their tricarboxylic acid (TCA) cycle. Here, we review findings indicating that NO, through its interaction with heme and non-heme metal containing proteins, together with components of the electron transport chain, functions not only as a regulator of cell respiration, but also a modulator of intracellular cell metabolism. Moreover, diverse effects of NO and NO-derived reactive nitrogen species (RNS) involve precise interactions with different targets depending on concentration, temporal, and spatial restrictions. Although the role of NO in macrophage reprogramming has been in evidence for some time, current models have largely minimized its importance. It has, therefore, been hiding in plain sight. A review of the chemical properties of NO, past biochemical studies, and recent publications, necessitates that mechanisms of macrophage TCA reprogramming during stimulation must be re-imagined and re-interpreted as mechanistic results of NO exposure. The revised model of metabolic rewiring we describe here incorporates many early findings regarding NO biochemistry and brings NO out of hiding and to the forefront of macrophages immunometabolism.

Targeting Heme Oxygenase-1 in the Arterial Response to Injury and Disease

Heme oxygenase-1 (HO-1) catalyzes the degradation of heme into carbon monoxide (CO), iron, and biliverdin, which is rapidly metabolized to bilirubin. The activation of vascular smooth muscle cells (SMCs) plays a critical role in mediating the aberrant arterial response to injury and a number of vascular diseases. Pharmacological induction or gene transfer of HO-1 improves arterial remodeling in animal models of post-angioplasty restenosis, vascular access failure, atherosclerosis, transplant arteriosclerosis, vein grafting, and pulmonary arterial hypertension, whereas genetic loss of HO-1 exacerbates the remodeling response. The vasoprotection evoked by HO-1 is largely ascribed to the generation of CO and/or the bile pigments, biliverdin and bilirubin, which exert potent antioxidant and anti-inflammatory effects. In addition, these molecules inhibit vascular SMC proliferation, migration, apoptosis, and phenotypic switching. Several therapeutic strategies are currently being pursued that may allow for the targeting of HO-1 in arterial remodeling in various pathologies, including the use of gene delivery approaches, the development of novel inducers of the enzyme, and the administration of unique formulations of CO and bilirubin.

Proteomic analysis of oxidative stress response in human umbilical vein endothelial cells (HUVECs): role of heme oxygenase 1 (HMOX1) in hypoxanthine-induced oxidative stress in HUVECs

Background

Erectile dysfunction (ED) is a well-known complication of diabetes, affecting up to 75% of diabetic men. Although the etiology of diabetic ED is multifactorial, endothelial dysfunction is considered to be a pillar of its pathophysiology. Endothelial dysfunction is caused by the harmful effects of high glucose levels and increased oxidative stress on the endothelial cells that comprise the vascular endothelium. The aim of this study was to identify the proteomic changes caused by high glucose-induced oxidative stress and explore the role of heme oxygenase 1 (HMOX1) in it.

Methods

The cellular proteomic response to hypoxanthine-induced oxidative stress in human umbilical vein endothelial cells (HUVECs) was analyzed by isobaric tags for relative and absolute quantitation (iTRAQ) combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS). Differentially expressed proteins (DEPs) were analyzed through Network and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses. Further validation assays was performed to validate the role of HMOX1.

Results

The results showed that 66 and 76 DEPs were markedly upregulated and downregulated, respectively, for HUVECs oxidative stress. Among these proteins, we verified eight dysregulated genes by quantitative reverse transcription PCR, including nucleolin (NCL), X-ray repair cross-complementing protein 6 (XRCC6), ubiquinol-cytochrome C reductase binding protein (UQCRB), non-POU domain containing octamer binding (NONO), heme oxygenase 1 (HMOX1), nucleobindin 1 (NUCB1), DEK, and chromatin target of prmt1 (CHTOP). Further, using overexpression and genetic knockdown approaches, we found that HMOX1 was critical for the oxidative stress response in HUVECs.

Conclusions

We found that HMOX1 was closely related to the oxidative stress response induced by hypoxanthine. To the best of our knowledge, this study is the first overview of the responses of HUVECs to oxidative stress. The findings will contribute to analyses of the detailed molecular mechanisms involved in the pathogenesis of endothelial dysfunction and related molecular mechanisms in ED patients.

Regulation of the Expression of Heme Oxygenase-1: Signal Transduction, Gene Promoter Activation, and Beyond

Significance: Heme oxygenase-1 (HO-1) is a ubiquitous 32-kDa protein expressed in many tissues and highly inducible. They catalyze the degradation of the heme group and the release of free iron, carbon monoxide, and biliverdin; the latter converted to bilirubin by biliverdin reductase. Its role in the regulation of cellular homeostasis is widely documented. Studying regulation of HO-1 expression is important not only to understand the life of healthy cells but also the unbalances in cell metabolism that lead to disease. Recent Advances: The regulation of its enzymatic activity depends heavily upon changes in expression studied mainly at the transcriptional level. Current knowledge regarding HO-1 gene expression focuses primarily on transcription factors such as Nrf2 (nuclear factor erythroid 2-related factor 2), AP-1 (activator protein-1), and hypoxia-inducible factor, which collect signal transduction pathway information at the HO-1 gene promoter. Understanding of gene expression regulation is not limited to transcription factor activity but also involves an extended range of post- or cotranscriptional regulated events. Critical Issues: In addition to the regulation of gene promoter activity, alternative splicing, alternative polyadenylation, and regulation of messenger RNA stability play critical roles in changes in HO-1 gene expression levels, involving specific factors, proteins, and microRNAs. All potential targets for diagnosis or treatment of diseases are related to HO-1 dysregulation. Future Directions: Unbalances in the tightly regulated gene expression mechanisms lead to cell transformation and cancer development. Knowledge of these events and signal transduction cascades triggered by oncogenes in which HO-1 plays a critical role is of upmost importance for research in this field.

BACH1 mediates the antioxidant properties of aged garlic extract

In clinical studies, aged garlic extract (AGE) has been shown to improve endothelial dysfunction. The activation of nuclear factor erythroid 2 like 2 (Nrf2)-dependent gene expression is a proposed mechanism for maintaining vascular homeostasis. S-1-propenylcysteine (S1PC) and S-allylcysteine (SAC) are two predominant sulfur-containing amino acids present in AGE. However, it remains unclear as to whether the two sulfur amino acids activate Nrf2 in cells. Nitric oxide (NO) is an important signaling molecule and one of the activators of the Nrf2 pathway. In a previous study, we examined the effects of the two sulfur amino acids on NO signaling for modulating the Nrf2-dependent antioxidant response. Neither S1PC nor SAC were found to affect the expression of Nrf2-regulated genes, such as heme oxygenase-1 (HMOX1) in human umbilical vein endothelial cells. However, S1PC was found to augment HMOX1 expression, induced by NO donors, such as NOR3. NOR3 was found to induce the nuclear accumulation of NRF2 protein and concomitantly enhance the degradation of BTB domain and CNC homolog 1 (BACH1), a transcriptional repressor that competes with NRF2. Notably, on our previous study, S1PC enhanced the NOR3-induced downregulation of BACH1, but did not further enhance the NOR3-induced accumulation of NRF2. The findings of that study indicated that the S1PC-induced degradation of BACH1 may provide a basis for the antioxidant effects of AGE. Thus, in this review, we aimed to provide a current overview of the antioxidant effects of AGE and sulfur-containing amino acids.

Crosstalk Between Oxidative Stress and Endoplasmic Reticulum (ER) Stress in Endothelial Dysfunction and Aberrant Angiogenesis Associated With Diabetes: A Focus on the Protective Roles of Heme Oxygenase (HO)-1

Type-2 diabetes prevalence is continuing to rise worldwide due to physical inactivity and obesity epidemic. Diabetes and fluctuations of blood sugar are related to multiple micro- and macrovascular complications, that are attributed to oxidative stress, endoplasmic reticulum (ER) activation and inflammatory processes, which lead to endothelial dysfunction characterized, among other features, by reduced availability of nitric oxide (NO) and aberrant angiogenic capacity. Several enzymatic anti-oxidant and anti-inflammatory agents have been found to play protective roles against oxidative stress and its downstream signaling pathways. Of particular interest, heme oxygenase (HO) isoforms, specifically HO-1, have attracted much attention as major cytoprotective players in conditions associated with inflammation and oxidative stress. HO operates as a key rate-limiting enzyme in the process of degradation of the iron-containing molecule, heme, yielding the following byproducts: carbon monoxide (CO), iron, and biliverdin. Because HO-1 induction was linked to pro-oxidant states, it has been regarded as a marker of oxidative stress; however, accumulating evidence has established multiple cytoprotective roles of the enzyme in metabolic and cardiovascular disorders. The cytoprotective effects of HO-1 depend on several cellular mechanisms including the generation of bilirubin, an anti-oxidant molecule, from the degradation of heme; the induction of ferritin, a strong chelator of free iron; and the release of CO, that displays multiple anti-inflammatory and anti-apoptotic actions. The current review article describes the major molecular mechanisms contributing to endothelial dysfunction and altered angiogenesis in diabetes with a special focus on the interplay between oxidative stress and ER stress response. The review summarizes the key cytoprotective roles of HO-1 against hyperglycemia-induced endothelial dysfunction and aberrant angiogenesis and discusses the major underlying cellular mechanisms associated with its protective effects.

Rescue of hematopoietic stem/progenitor cells formation in plcg1 zebrafish mutant

Hematopoietic stem/progenitor cells (HSPC) in zebrafish emerge from the aortic hemogenic endothelium (HE) and migrate towards the caudal hematopoietic tissue (CHT), where they expand and differentiate during definitive hematopoiesis. Phospholipase C gamma 1 (Plcγ1) has been implicated for hematopoiesis in vivo and in vitro and is also required to drive arterial and HSPC formation. Genetic mutation in plcg1-/- (y10 allele) completely disrupts the aortic blood flow, specification of arterial fate, and HSPC formation in zebrafish embryos. We previously demonstrated that ginger treatment promoted definitive hematopoiesis via Bmp signaling. In this paper, we focus on HSPC development in plcg1-/- mutants and show that ginger/10-gingerol (10-G) can rescue the expression of arterial and HSPC markers in the HE and CHT in plcg1-/- mutant embryos. We demonstrate that ginger can induce scl/runx1 expression, and that rescued HE fate is dependent on Bmp and Notch. Bmp and Notch are known to regulate nitric oxide (NO) production and NO can induce hematopoietic stem cell fate. We show that ginger produces a robust up-regulation of NO. Taken together, we suggest in this paper that Bmp, Notch and NO are potential players that mediate the effect of ginger/10-G for rescuing the genetic defects in blood vessel specification and HSPC formation in plcg1-/- mutants. Understanding the molecular mechanisms of HSPC development in vivo is critical for understanding HSPC expansion, which will have a positive impact in regenerative medicine.

Sepiapterin alleviates impaired gastric nNOS function in spontaneous diabetic female rodents through NRF2 mRNA turnover and miRNA biogenesis pathway

An impaired nitrergic system and altered redox signaling contribute to gastric dysmotility in diabetics. Our earlier studies show that NF-E2-related factor 2 (NRF2) and phase II antioxidant enzymes play a vital role in gastric neuronal nitric oxide synthase (nNOS) function. This study aims to investigate whether supplementation of sepiapterin (SEP), a precursor for tetrahydrobiopterin (BH₄) (a cofactor of NOS) via the salvage pathway, restores altered nitrergic systems and redox balance in spontaneous diabetic (DB) female rats. Twelve-week spontaneous DB and age-matched, non-DB rats, with and without dietary SEP (daily 20 mg/kg body wt for 10 days) treatment, were used in this study. Gastric antrum muscular tissues were excised to investigate the effects of SEP in nitrergic relaxation and the nNOS-nitric oxide (NO)-NRF2 pathway(s). Dietary SEP supplementation significantly ( P < 0.05) reverted diabetes-induced changes in nNOS dimerization and function; nitric oxide (NO) downstream signaling molecules; HSP-90, a key regulator of nNOSα activity and dimerization; miRNA-28 that targets NRF2 messenger RNA (mRNA), and levels of microRNA (miRNA) biogenesis pathway components, such as DGCR8 (DiGeorge Syndrome Critical Region Gene 8) and TRBP (HIV1-1 transactivating response RNA-binding protein). These findings emphasize the importance of the BH₄ pathway in regulating gastric motility functions in DB animals by modulating nNOSα dimerization in association with changes in enteric NRF2 and NO downstream signaling. Our results also identify a new pathway, wherein SEP regulates NRF2 mRNA turnover by suppressing elevated miRNA-28, which could be related to alterations in miRNA biogenesis pathway components. NEW & NOTEWORTHY This study is the first to show a causal link between NF-E2-related factor 2 (NRF2) and neuronal nitric oxide synthase (nNOS) in gastric motility function. Our data demonstrate that critical regulators of the miRNA biosynthetic pathway are upregulated in the diabetic (DB) setting; these regulators were rescued by sepiapterin (SEP) treatment. Finally, we show that low dihydrofolate reductase expression may lead to impaired nNOS dimerization/function-reduced nitric oxide downstream signaling and elevate oxidative stress by suppressing the NRF2/phase II pathway through miRNA; SEP treatment restored all of the above in DB gastric muscular tissue. We suggest that tetrahydrobiopterin supplementation may be a useful therapy for patients with diabetes, as well as women with idiopathic gastroparesis.

Nrf2 in aging - Focus on the cardiovascular system

Aging is the most critical risk factor for the development of cardiovascular diseases and their complications. Therefore, the fine-tuning of cellular response to getting older is an essential target for prospective therapies in cardiovascular medicine. One of the most promising targets might be the transcription factor Nrf2, which drives the expression of cytoprotective and antioxidative genes. Importantly, Nrf2 expression correlates with potential lifespan in rodents. However, the effect of Nrf2 activity in vascular diseases might be ambiguous and strongly depend on the cell type. On the one hand, the Nrf2 activity may protect cells from oxidative stress and senescence, on the other hand, total lack of Nrf2 is protective against atherosclerosis development. Therefore, this review aims to discuss the current knowledge on the role played by the transcription factor Nrf2 in cardiovascular diseases and its potential effects on aging.

Implications of aging and the endoplasmic reticulum unfolded protein response on the molecular modality of breast cancer

The endoplasmic reticulum (ER) is an important subcellular organelle that is involved in numerous activities required to achieve and maintain functional proteins in addition to its role in the biosynthesis of lipids and as a repository of intracellular Ca²⁺. The inability of the ER to cope with protein folding beyond its capacity causes disturbances that evoke ER stress. Cells possess molecular mechanisms aimed at clearing unwanted cargo from the ER lumen as an adaptive response, but failing to do so navigates the system towards cell death. This systemic approach is called the unfolded protein response. Aging insults cells through various perturbations in homeostasis that involve curtailing ER function by mitigating the expression of its resident chaperones and enzymes. Here the unfolded protein response (UPR) cannot protect the cell due to the weakening of its protective arm, which exacerbates imbalanced homeostasis. Aging predisposed breast malignancy activates the UPR, but tumor cells maneuver the mechanistic details of the UPR, favoring tumorigenesis and thereby eliciting a treacherous condition. Tumor cells exploit UPR pathways via crosstalk involving various signaling cascades that usher tumor cells to immortality. This review aims to present a collection of data that can delineate the missing links of molecular signatures between aging and breast cancer.

Carnosic acid prevents dextran sulfate sodium-induced acute colitis associated with the regulation of the Keap1/Nrf2 pathway

Crohn's disease and ulcerative colitis are inflammatory bowel diseases (IBDs) with high prevalence in humans. Carnosic acid (CA) has been reported to possess antioxidative properties; however, its role in IBDs has not been determined. In the present study, we found that CA significantly prevented the loss of body weight and shortening of colon length in acute colitis induced by dextran sodium sulfate (DSS). Pronounced infiltration of immune cells and a loss of crypt architecture and goblet cells were ameliorated by CA. CA significantly decreased the activity of MPO and infiltration of F4/80⁺ macrophages in the colon. DSS-induced pro-inflammatory cytokine mRNA and protein levels in the colon were also attenuated by CA. CA decreased the activation of p65 and c-Jun signalling. CA inhibited DSS-induced NLRP3 inflammasome activation by reducing caspase 1 activity. In addition, CA increased the level of Nrf2 and prevented the degradation of Nrf2 via ubiquitination by blocking the interaction between Cullin3 and Keap1, which resulted in the decrease of Nrf2 target genes. Finally, GSH levels and SOD activity were increased after CA treatment, while MDA and iNOS levels were significantly reduced. Taken together, our data showed that CA may be useful as a potential therapeutic candidate for IBDs.

Immunobiology of Nitric Oxide and Regulation of Inducible Nitric Oxide Synthase

Nitric oxide (NO) is a bioactive gas that has multiple roles in innate and adaptive immune responses. In macrophages, nitric oxide is produced by inducible nitric oxide synthase upon microbial and cytokine stimulation. It is needed for host defense against pathogens and for immune regulation. This review will summarize the role of NO and iNOS in inflammatory and immune responses and will discuss the regulatory mechanisms that control inducible nitric oxide synthase expression and activity.

Signal transduction involved in lipoxin A4‑induced protection of tubular epithelial cells against hypoxia/reoxygenation injury

Previous studies have reported that lipoxin A₄ (LXA₄) may exert a renoprotective effect on ischemia/reperfusion injury in various animal models. The underlying mechanism of LXA₄-induced renoprotection during ischemia/reperfusion injury remains to be elucidated. The present study investigated LXA₄-induced protection on renal tubular cells subjected to hypoxia/reoxygenation (H/R) injury, and determined the effects of peroxisome proliferator-activated receptor-γ (PPARγ) and heme oxygenase-1 (HO-1) on LXA₄ treatment. HK-2 human tubular epithelial cells exposed to H/R injury were pretreated with LXA₄, signal molecule inhibitors or the HO-1 inhibitor zinc protoporphyrin-IX, or were transfected with PPARγ small interfering RNA (siRNA) or nuclear factor E2-related factor 2 (Nrf2) siRNA. The protein and mRNA expression levels of PPARγ and HO-1 were analyzed using western blotting and reverse transcription-quantitative polymerase chain reaction. Binding activity of Nrf2 to the HO-1 E1 enhancer was determined using chromatin immunoprecipitation. Nrf2 binding to the HO-1 antioxidant responsive element (ARE) was assessed using electrophoretic mobility shift assay. Preincubation of cells with LXA₄ exposed to H/R injury led to a decreased production of inducible nitrogen oxide synthase, malondialdehyde, γ-glutamyl transpeptidase, leucine aminopeptidase and N-acetyl-β-glucosaminidase. In addition, LXA₄ pretreatment increased cell viability, protein and mRNA expression levels of PPARγ and HO-1 and PPARγ and HO-1 promoter activity. SB20358 is a p38 mitogen-activated protein kinase (p38 MAPK) pathway inhibitor, which reduced LXA₄-induced PPARγ expression levels. LXA₄ treatment upregulated p38 MAPK activation, Nrf2 nuclear translocation and increased binding activity of Nrf2 to HO-1 ARE and E1 enhancer in cells exposed to H/R injury. Transfection of the cells with PPARγ siRNA reduced the LXA₄-induced Nrf2 translocation. Transfection of the cells with PPARγ siRNA or Nrf2 siRNA also reduced the LXA₄-induced increase in HO-1 expression. In conclusion, LXA₄-induced protection of renal tubular cells against H/R injury was associated with the induction of PPARγ and HO-1, via activation of the p38 MAPK pathway, as well as Nrf2 nuclear translocation and binding to HO-1 ARE and E1 enhancer. Therefore, LXA₄-induced renoprotection is associated with activation of the p38 MAPK/PPARγ/Nrf2-ARE/HO-1 pathway.

Effect of Paeotang on tumor necrosis factor α-induced vascular inflammation in human umbilical vein endothelial cells

OBJECTIVE

To investigate whether Paeotang (10-50 μg/mL) suppresses tumor necrosis factor α (TNF-α)-induced vascular inflammatory processes in human umbilical vein endothelial cells (HUVEC).

METHODS

The ingredients composed of Paeotang include Glycyrrhiza glabra, Zingiber officinale, Cinnamomum zeylanuicum, Salvia miltiorrhiza, Prunus persica, Paeonia szechuanica, Poria cocos and Cynanchum wilfordii. Herbs were mixed according to equal ratio of weight and ground into a crude powder. The effect of Paeotang on the expression of cell adhesion molecules and protective role in HUVEC stimulated by TNF-α were evaluated.

RESULTS

Pretreatment with Paeotang decreased TNF-α-induced adhesion of HL-60 monocytic cells, as well as protein and mRNA expressions of intracellular adhesion molecule 1 (ICAM-1), vascular cell adhesion molecule 1 (VCAM-1) and endothelial-selectin (E-selectin). Paeotang also dose-dependently inhibited TNF-α-induced matrix metalloproteinase-2 and -9 expressions. Paeotang significantly decreased TNF-α-induced intracellular reactive oxygen species (ROS) production. The Western blot and immunofluorescence analysis showed that Paeotang suppressed the translocation of p65 nuclear factor κB (NF-κB) to the nucleus. In addition, Paeotang inhibited the TNF-α-induced degradation of NF-κB inhibitor α (IκB-α) and by inhibiting the phosphorylation of IκB-α. Furthermore, pretreatment of Paeotang increased the heme oxygenase 1 (HO-1) and nuclear factor erythroid-2-related factor 2 (Nrf2) protein expression in HUVECs stimulated TNF-α. HO-1 was inhibited by Sn-protoporphyrin, HO-1 inhibitor, and increased by cobalt protopophyrin, HO-1 inducer. Furthermore, HO-1 induction was increased by single processing of Paeotang in a dose-dependent manner.

CONCLUSION

These data suggest that Paeotang might be a benefificial therapeutic in vascular inflflammation through regulation of Nrf2-mediated HO-1 expression and inhibition of ROS/NF-κB signaling pathway. Thus, Paeotang maybe serve as a potential anti-atherogenic agent.

Ammonia promotes endothelial cell survival via the heme oxygenase-1-mediated release of carbon monoxide

Although endothelial cells produce substantial quantities of ammonia during cell metabolism, the physiologic role of this gas in these cells is not known. In this study, we investigated if ammonia regulates the expression of heme oxygenase-1 (HO-1), and if this enzyme influences the biological actions of ammonia on endothelial cells. Exogenously administered ammonia, given as ammonium chloride or ammonium hydroxide, or endogenously generated ammonia stimulated HO-1 protein expression in cultured human and murine endothelial cells. Dietary supplementation of ammonia also induced HO-1 protein expression in murine arteries. The increase in HO-1 protein by ammonia in endothelial cells was first detected 4h after ammonia exposure and was associated with the induction of HO-1 mRNA, enhanced production of reactive oxygen species (ROS), and increased expression and activity of NF-E2-related factor-2 (Nrf2). Ammonia also activated the HO-1 promoter and this was blocked by mutating the antioxidant responsive element or by overexpressing dominant-negative Nrf2. The induction of HO-1 expression by ammonia was dependent on ROS formation and prevented by N-acetylcysteine or rotenone. Finally, prior treatment of endothelial cells with ammonia inhibited tumor necrosis factor-α-stimulated cell death. However, silencing HO-1 expression abrogated the protective action of ammonia and this was reversed by the administration of carbon monoxide but not bilirubin or iron. In conclusion, this study demonstrates that ammonia stimulates the expression of HO-1 in endothelial cells via the ROS-Nrf2 pathway, and that the induction of HO-1 contributes to the cytoprotective action of ammonia by generating carbon monoxide. Moreover, it identifies ammonia as a potentially important signaling gas in the vasculature that promotes endothelial cell survival.

Protective role of phenylalanine on the ROS-induced oxidative damage, apoptosis and tight junction damage via Nrf2, TOR and NF-κB signalling molecules in the gill of fish

This study explored the possible preventive effects of dietary phenylalanine (Phe) on antioxidant responses, apoptosis and tight junction protein transcription in the gills of young grass carp (Ctenopharyngodon idella). Fish were fed six different experimental diets containing graded levels of Phe (3.4-16.8 g kg^-1) for 8 weeks. The results showed that Phe deficiency induced protein oxidation and lipid peroxidation by decreasing the glutathione content and the activities and mRNA levels of Cu/Zn superoxide dismutase (SOD1), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR) and glutathione-S-transferase (GST) in fish gill (P < 0.05). These results may be ascribed to the downregulation of NF-E2-related factor 2 (Nrf2), target of rapamycin (TOR) and ribosomal protein S6 kinase 1 (S6K1), and the upregulation of Kelch-like-ECH-associated protein 1 a (Keap1a) expression in grass carp gills (P < 0.05). Additionally, Phe deficiency induced DNA fragmentation via the up-regulation of Caspase 3, Caspase 8 and Caspase 9 mRNA expression (P < 0.05). These results may be ascribed to the improvement in reactive oxygen species (ROS) levels in the fish gills (P < 0.05). Furthermore, the results indicated that Phe deficiency decreased Claudin b, Claudin 3, Occludin and ZO-1 transcription and increased Claudin 15 expression in the fish gills (P < 0.05). These effects were partly due to the downregulation of interleukin 10 (IL-10), transforming growth factor β (TGF-β) and inhibitor factor κBα (iκBα) and the upregulation of relative mRNA expression of interleukin 1β (IL-1β), interleukin 8 (IL-8), tumour necrosis factor-α (TNF-α) and nuclear transcription factor-κB p65 (NF-κB p65) (P < 0.05). Taken together, the results showed that Phe deficiency impaired the structural integrity of fish gills by regulating the expression of tight junction proteins, cytokines, antioxidant enzymes, NF-κB p65, iκBα, TOR, Nrf2, Keap1 and apoptosis-related genes in the fish gills.

Heme Oxygenases in Cardiovascular Health and Disease

Heme oxygenases are composed of two isozymes, Hmox1 and Hmox2, that catalyze the degradation of heme to carbon monoxide (CO), ferrous iron, and biliverdin, the latter of which is subsequently converted to bilirubin. While initially considered to be waste products, CO and biliverdin/bilirubin have been shown over the last 20 years to modulate key cellular processes, such as inflammation, cell proliferation, and apoptosis, as well as antioxidant defense. This shift in paradigm has led to the importance of heme oxygenases and their products in cell physiology now being well accepted. The identification of the two human cases thus far of heme oxygenase deficiency and the generation of mice deficient in Hmox1 or Hmox2 have reiterated a role for these enzymes in both normal cell function and disease pathogenesis, especially in the context of cardiovascular disease. This review covers the current knowledge on the function of both Hmox1 and Hmox2 at both a cellular and tissue level in the cardiovascular system. Initially, the roles of heme oxygenases in vascular health and the regulation of processes central to vascular diseases are outlined, followed by an evaluation of the role(s) of Hmox1 and Hmox2 in various diseases such as atherosclerosis, intimal hyperplasia, myocardial infarction, and angiogenesis. Finally, the therapeutic potential of heme oxygenases and their products are examined in a cardiovascular disease context, with a focus on how the knowledge we have gained on these enzymes may be capitalized in future clinical studies.

Dietary vitamin C deficiency depresses the growth, head kidney and spleen immunity and structural integrity by regulating NF-κB, TOR, Nrf2, apoptosis and MLCK signaling in young grass carp (Ctenopharyngodon idella)

This study investigated the effects of dietary vitamin C on the growth, and head kidney, spleen and skin immunity, structural integrity and related signaling molecules mRNA expression levels of young grass carp (Ctenopharyngodon idella). A total of 540 grass carp (264.37 ± 0.66 g) were fed six diets with graded levels of vitamin C (2.9, 44.2, 89.1, 133.8, 179.4 and 224.5 mg/kg diet) for 10 weeks. Subsequently, a challenge test was conducted by injection of Aeromonas hydrophila and the survival rate recorded for 14 days. The results indicated that compared with optimal vitamin C supplementation, vitamin C deficiency (2.9 mg/kg diet) decreased lysozyme (LA) and acid phosphatase (ACP) activities, and complement 3 and complement 4 (C4) contents (P < 0.05), down-regulated the mRNA levels of antimicrobial peptides [liver expressed antimicrobial peptide (LEAP) 2A, LEAP-2B, hepcidin, β-defensin] and anti-inflammatory cytokines-related factors, interleukin (IL) 4/13A, IL-4/13B (only in head kidney), IL-10, IL-11, transforming growth factor (TGF) β1, TGF-β2, inhibitor of κBα and eIF4E-binding protein 1 (P < 0.05), and up-regulated pro-inflammatory cytokines-related factors, tumor necrosis factor α, interferon γ2, IL-1β, IL-6, IL-8, IL-12 P35 (only in spleen), IL-12 P40, IL-15, IL-17D, nuclear factor κB p65, IκB kinases (IKKα, IKKβ, IKKγ), target of rapamycin and ribosomal protein S6 kinase 1 mRNA levels (P < 0.05) in the head kidney and spleen under injection fish of A. hydrophila, suggesting that vitamin C deficiency could decrease fish head kidney and spleen immunity and cause inflammation. Meanwhile, compared with optimal vitamin C supplementation, vitamin C deficiency decreased the activities and mRNA levels of copper/zinc superoxide dismutase, manganese superoxide dismutase (MnSOD), catalase, glutathione peroxidase, glutathione S-transferases and glutathione reductase (P < 0.05), and down-regulated zonula occludens (ZO) 1, ZO-2, Claudin-b, -c, -3c, -7a, -7b, B-cell lymphoma-2, inhibitor of apoptosis protein, NF-E2-related factor 2 mRNA levels (P < 0.05), increased reactive oxygen species (ROS), malondialdehyde (MDA) and protein carbonyl contents (P < 0.05), and up-regulated Claudin-12, 15a, -15b, Fas ligand, mitogen-activated protein kinase kinase 6, p38 mitogen-activated protein kinase, B-cell lymphoma protein 2 associated X protein, apoptotic protease activating factor-1, caspase-3, -7, -8, -9, Kelch-like ECH-associating protein (Keap) 1a and Keap 1b mRNA levels (P < 0.05) in the head kidney and spleen under injection fish of A. hydrophila, suggesting that vitamin C deficiency could decrease fish head kidney and spleen structural integrity through depression of antioxidative ability, induction of apoptosis and disruption of tight junctional complexes. In addition, except the activities of ACP and MnSOD, and mRNA expression levels of TGF-β1, Occludin and MnSOD, the effect of vitamin C on fish head kidney, spleen and skin immunity and structural integrity other indicators model are similar under infection of A. hydrophila. Finally, the vitamin C requirement for the growth performance (PWG) of young grass carp was estimated to be 92.8 mg/kg diet. Meanwhile, the vitamin C requirement for against skin lesion morbidity of young grass carp was estimated to be 122.9 mg/kg diet. In addition, based on the biochemical indices [immune indices (LA activity in the head kidney and C4 content in the spleen) and antioxidant indices (MDA content in the head kidney and ROS content in the spleen)] the vitamin C requirements for young grass carp were estimated to be 131.2, 137.5, 135.8 and 129.8 mg/kg diet, respectively.

Preconditioning c-Kit-positive Human Cardiac Stem Cells with a Nitric Oxide Donor Enhances Cell Survival through Activation of Survival Signaling Pathways

Cardiac stem cell therapy has shown very promising potential to repair the infarcted heart but is severely limited by the poor survival of donor cells. Nitric oxide (NO) has demonstrated cytoprotective properties in various cells, but its benefits are unknown specifically for human cardiac stem cells (hCSCs). Therefore, we investigated whether pretreatment of hCSCs with a widely used NO donor, diethylenetriamine nitric oxide adduct (DETA-NO), promotes cell survival. Results from lactate dehydrogenase release assays showed a dose- and time-dependent attenuation of cell death induced by oxidative stress after DETA-NO preconditioning; this cytoprotective effect was abolished by the NO scavenger. Concomitant up-regulation of several cell signaling molecules after DETA-NO preconditioning was observed by Western blotting, including elevated phosphorylation of NRF2, NFκB, STAT3, ERK, and AKT, as well as increased protein expression of HO-1 and COX2. Furthermore, pharmaceutical inhibition of ERK, STAT3, and NFκB activities significantly diminished NO-induced cytoprotection against oxidative stress, whereas inhibition of AKT or knockdown of NRF2 only produced a minor effect. Blocking PI3K activity or knocking down COX2 expression did not alter the protective effect of DETA-NO on cell survival. The crucial roles of STAT3 and NFκB in NO-mediated signaling pathways were further confirmed by stable expression of gene-specific shRNAs in hCSCs. Thus, preconditioning hCSCs with DETA-NO promotes cell survival and resistance to oxidative stress by activating multiple cell survival signaling pathways. These results will potentially provide a simple and effective strategy to enhance survival of hCSCs after transplantation and increase their efficacy in repairing infarcted myocardium.

Heme as a danger molecule in pathogen recognition

Appropriate control of redox mechanisms are critical for and effective innate immune response, which employs multiple cell types, receptors and molecules that recognize danger signals when they reach the host. Recognition of pathogen-associated pattern molecules (PAMPs) is a fundamental host survival mechanism for efficient elimination of invading pathogens and resolution of the infection and inflammation. In addition to PAMPs, eukaryotic cells contain a plethora of intracellular molecules that are normally secured within the confines of the plasma membrane, but if liberated and encountered in the extracellular milieu can provoke rapid cell activation. These are known as Alarmins or Danger-Associated Molecular Patterns (DAMPs) and can be released actively by cells or passively as a result of sterile cellular injury after trauma, ischemia, or toxin-induced cell rupture. Both PAMPs and DAMPs are recognized by a series of cognate receptors that increase the generation of free radicals and activate specific signaling pathways that result in regulation of a variety of stress response, redox sensitive genes. Multiple mediators released, as cells die include, but are not limited to ATP, hydrogen peroxide, heme, formyl peptides, DNA or mitochondria provide the second signal to amplify immune responses. In this review, we will focus on how sterile and infective stimuli activate the stress response gene heme oxygenase-1 (Hmox1, HO-1), a master gene critical to an appropriate host response that is now recognized as one with enormous therapeutic potential. HO-1 gene expression is regulated in large part by redox-sensitive proteins including but not limited to nrf2. Both PAMPs and DAMPs increase the activation of nrf2 and HO-1. Heme is a powerful pro-oxidant and as such should be qualified as a DAMP. With its degradation by HO-1a molecule of carbon monoxide (CO) is generated that in turn serves as a bioactive signaling molecule. PAMPs such as bacterial endotoxin activate HO-1, and the CO that is generated diffuses into the extracellular milieu where it interacts with bacteria, altering their behavior to increase production of ATP, which then functions as a second signal danger molecule. This two-hit cycle scenario results in efficient and effective activation of host leukocytes to attack and clear bacteria in part via enhanced reactive oxygen species generation. We discuss this intimate communication that occurs between host and bacteria and how these molecules serve as critical regulators of the acute inflammatory response, the overall redox status of the cell, and survival of the host.

Folic acid deficiency impairs the gill health status associated with the NF-κB, MLCK and Nrf2 signaling pathways in the gills of young grass carp (Ctenopharyngodon idella)

The aim of this study was to investigate the effect of dietary folic acid on fish growth, the immune and barrier functions of fish gills, and the potential mechanisms of these effects. Young grass carp (Ctenopharyngodon idella) were fed diets containing graded levels of folic acid at 0.10 (basal diet), 0.47, 1.03, 1.48, 1.88 and 3.12 mg kg(-1) diet for 8 weeks. The results showed that acid phosphatase and lysozyme activities and the complement component 3 content in fish gills decreased with folic acid deficiency (P < 0.05). Folic acid deficiency up-regulated liver-expressed antimicrobial peptide 1, interleukin 1β, interleukin 8, tumor necrosis factor α, nuclear factor κB p65, IκB kinase α (IKK-α), IKK-β and IKK-γ gene expression. Folic acid deficiency down-regulated interleukin 10, transforming growth factor β, IκB and target of rapamycin gene expression in fish gills (P < 0.05). These results showed that limited folic acid decreased fish gill immune status. Furthermore, folic acid deficiency down-regulated claudin-b, claudin-c, claudin-3, occludin and zonula occludens 1 gene expression, whereas folic acid deficiency up-regulated claudin-12, claudin-15, myosin light chain kinase and p38 mitogen activated protein kinase gene expression in fish gills (P < 0.05). These results suggested that folic acid deficiency disrupted tight junction-mediated fish gill barrier function. Additionally, folic acid deficiency increased the content of reactive oxygen species, protein carbonyl and malondialdehyde (MDA); Mn superoxide dismutase activity and gene expression; and Kelch-like-ECH-associated protein 1a (Keap1a) and Keap1b gene expression (P < 0.05). Conversely, folic acid deficiency decreased Cu/Zn superoxide dismutase, catalase, glutathione peroxidase, glutathione s-transferases and glutathione reductase activities and gene expression as well as NF-E2-related factor 2 gene expression in fish gills (P < 0.05). All of these results indicated that folic acid deficiency impaired fish gill health status via regulating gene expression of cytokines, tight junction proteins, antioxidant enzymes, NF-κB p65, MLCK and Nrf2. Based on percent weight gain, LZ activity and MDA content in the gills, the dietary folic acid requirements for young grass carp were 1.60, 2.07 and 2.08 mg kg(-1), respectively.

Gaseous modulators in the control of the hypothalamic neurohypophyseal system

Nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H2S) are gaseous molecules produced by the brain. Within the hypothalamus, gaseous molecules have been highlighted as autocrine and paracrine factors regulating endocrine function. Therefore, in the present review, we briefly discuss the main findings linking NO, CO, and H2S to the control of body fluid homeostasis at the hypothalamic level, with particular emphasis on the regulation of neurohypophyseal system output.

Dietary riboflavin deficiency decreases immunity and antioxidant capacity, and changes tight junction proteins and related signaling molecules mRNA expression in the gills of young grass carp (Ctenopharyngodon idella)

This study investigated the effects of dietary riboflavin on the growth, gill immunity, tight junction proteins, antioxidant system and related signaling molecules mRNA expression of young grass carp (Ctenopharyngodon idella). Fish were fed six diets containing graded levels of riboflavin (0.63-10.04 mg/kg diet) for 8 weeks. The study indicated that riboflavin deficiency decreased lysozyme and acid phosphatase activities, and complement component 3 content in the gills of fish (P < 0.05). Moreover, riboflavin deficiency caused oxidative damage, which might be partly due to decrease copper, zinc superoxide dismutase, catalase, glutathione reductase, glutathione peroxidase and glutathione-S-transferase activities and reduced glutathione content in the gills of fish (P < 0.05). Furthermore, the relative mRNA levels of antimicrobial peptides (liver expressed antimicrobial peptide 2 and Hepcidin), anti-inflammatory cytokines (interleukin 10 and transforming growth factor β1), tight junction proteins (Occludin, zonula occludens 1, Claudin-c and Claudin-3), signaling molecules (inhibitor of κBα, target of rapamycin and NF-E2-related factor 2) and antioxidant enzymes (copper, zinc superoxide dismutase and glutathione reductase) were significantly decreased (P < 0.05) in the gills of fish fed riboflavin-deficient diet. Conversely, the mRNA levels of pro-inflammatory cytokines (tumor necrosis factor α, interleukin 8, interferon γ2, and interleukin 1β), signaling molecules (nuclear factor kappa B p65, IκB kinase β, IκB kinase γ, Kelch-like-ECH-associated protein 1b and myosin light chain kinase) and tight junction protein Claudin-12 were significantly increased (P < 0.05) in the gills of fish fed riboflavin-deficient diet. In addition, this study indicated for the first time that young fish fed a riboflavin-deficient diet exhibited anorexia and poor growth. In conclusion, riboflavin deficiency decreased growth and gill immunity, impaired gill antioxidant system, as well as regulated mRNA expression of gill tight junction proteins and related signaling molecules of fish. Based on percent weight gain, gill lysozyme activity and reduced glutathione content, the dietary riboflavin requirements for young grass carp (275-722 g) were estimated to be 5.85, 7.39 and 6.34 mg/kg diet, respectively.

Dietary phenylalanine-improved intestinal barrier health in young grass carp (Ctenopharyngodon idella) is associated with increased immune status and regulated gene expression of cytokines, tight junction proteins, antioxidant enzymes and related signalling molecules

The present work evaluated the effects of dietary phenylalanine (Phe) on the intestinal immune response, tight junction proteins transcript abundance, and the gene expression of immune- and antioxidant-related signalling molecules in the intestine. In addition, the dietary Phe (and Phe + Tyr) requirement of young grass carp (Ctenopharyngodon idella) was also estimated. Fish were fed fish meal-casein-gelatin based diets (302.3 g crude protein kg(-1)) containing 3.4 (basal diet), 6.1, 9.1, 11.5, 14.0 and 16.8 g Phe kg(-1) with a fixed amount of 10.7 g tyrosine kg(-1) for 8 weeks. The results showed that Phe deficiency or excess Phe reduced the lysozyme and acid phosphatase activities and complement C 3 content in the intestine (P < 0.05). Moreover, zonula occludens-1 (ZO-1), occludin and claudin c mRNA levels were highest in the fish fed the diet containing 11.5 g Phe kg(-1) (P < 0.05). However, claudin 12 and claudin b mRNA levels were not significantly affected by dietary Phe (P > 0.05). Gene expression of interleukin-10 (IL-10), transforming growth factor-β1 (TGF-β1), target of rapamycin (TOR) and inhibitor of nuclear factor κBα (IκBα) in proximal intestine (PI), mid intestine (MI) and distal intestine (DI) increased as dietary Phe increased up to 6.1, 9.1, 11.5 and 14.0 g kg(-1), respectively (P < 0.05). However, interleukin-8 (IL-8), tumour necrosis factor-α (TNF-α) and nuclear factor-κB p65 (NF-κB p65) mRNA levels showed opposite tendencies. In addition, the mRNA level of superoxide dismutase (SOD) was significantly lower in the intestinal tissue of the group fed a diet with Phe levels of 16.8 g kg(-1) than in those of other groups (P < 0.05). The expression of NF-E2-related factor 2 (Nrf2) gene was increased as dietary Phe increased up to 9.1 g kg(-1) (P < 0.05). In conclusion, Phe improved intestinal immune status, and regulated gene expression of cytokines, tight junction proteins, antioxidant enzymes, NF-κB p65, IκBα, TOR, and Nrf2 in the fish intestine. Based on the quadratic regression analysis of lysozyme activity at a 95% maximum, the dietary Phe requirement of young grass carp (256-629 g) was estimated to be 8.31 g kg(-1), corresponding to 2.75 g 100 g(-1) protein.

Adiponectin ameliorates hyperglycemia-induced cardiac hypertrophy and dysfunction by concomitantly activating Nrf2 and Brg1

Hyperglycemia-induced oxidative stress is implicated in the development of cardiomyopathy in diabetes that is associated with reduced adiponectin (APN) and heme oxygenase-1 (HO-1). Brahma-related gene 1 (Brg1) assists nuclear factor-erythroid-2-related factor-2 (Nrf2) to activate HO-1 to increase myocardial antioxidant capacity in response to oxidative stress. We hypothesized that reduced adiponectin (APN) impairs HO-1 induction which contributes to the development of diabetic cardiomyopathy, and that supplementation of APN may ameliorate diabetic cardiomyopathy by activating HO-1 through Nrf2 and Brg1 in diabetes. Control (C) and streptozotocin-induced diabetic (D) rats were untreated or treated with APN adenovirus (1×10(9) pfu) 3 weeks after diabetes induction and examined and terminated 1 week afterward. Rat left ventricular functions were assessed by a pressure-volume conductance system, before the rat hearts were removed to perform histological and biochemical assays. Four weeks after diabetes induction, D rats developed cardiac hypertrophy evidenced as increased ratio of heart weight to body weight, elevated myocardial collagen I content, and larger cardiomyocyte cross-sectional area (all P<0.05 vs C). Diabetes elevated cardiac oxidative stress (increased 15-F2t-isoprostane, 4-hydroxynonenal generation, 8-hydroxy-2'-deoxyguanosine, and superoxide anion generation), increased myocardial apoptosis, and impaired cardiac function (all P<0.05 vs C). In D rats, myocardial HO-1 mRNA and protein expression were reduced which was associated with reduced Brg1 and nuclear Nrf2 protein expression. All these changes were either attenuated or prevented by APN. In primarily cultured cardiomyocytes (CMs) isolated from D rats or in the embryonic rat cardiomyocytes cell line H9C2 cells incubated with high glucose (HG, 25 mM), supplementation of recombined globular APN (gAd, 2μg/mL) reversed HG-induced reductions of HO-1, Brg1, and nuclear Nrf2 protein expression and attenuated cellular oxidative stress, myocyte size, and apoptotic cells. Inhibition of HO-1 by ZnPP (10μM) or small interfering RNA (siRNA) canceled all the above gAd beneficial effects. Moreover, inhibition of Nrf2 (either by the Nrf2 inhibitor luteolin or siRNA) or Brg1 (by siRNA) canceled gAd-induced HO-1 induction and cellular protection in CMs and in H9C2 cells incubated with HG. In summary, our present study demonstrated that APN reduced cardiac oxidative stress, ameliorated cardiomyocyte hypertrophy, and prevented left ventricular dysfunction in diabetes by concomitantly activating Nrf2 and Brg1 to facilitate HO-1 induction.

A Preliminary Study on Racial Differences in HMOX1, NFE2L2, and TGFβ1 Gene Polymorphisms and Radiation-Induced Late Normal Tissue Toxicity

PURPOSE

This study tested whether racial differences in genetic polymorphisms of 4 genes involved in wound repair and response to radiation can be used to predict the occurrence of normal tissue late effects of radiation therapy and indicate potential therapeutic targets.

METHODS AND MATERIALS

This prospective study examined genetic polymorphisms that modulate the expression of 4 genes involved in inflammation and fibrosis and response to radiation (HMOX1, NFE2L2, NOS3, and TGFβ1). DNA from blood samples of 179 patients (∼ 80% breast and head and neck) collected at the time of diagnosis by their radiation oncologist as exhibiting late normal tissue toxicity was used for the analysis. Patient demographics were as follows: 56% white, 43% African American, 1% other. Allelic frequencies of the different polymorphisms of the participants were compared with those of the general American population stratified by race. Twenty-six additional patients treated with radiation, but without toxicity at 3 months or later after therapy, were also analyzed.

RESULTS

Increased frequency of a long GT repeat in the HMOX1 promoter was associated with late effects in both African American and white populations. The single nucleotide polymorphisms (SNP) rs1800469 in the TGFβ1 promoter and the rs6721961 SNP in the NFE2L2 promoter were also found to significantly associate with late effects in African Americans but not whites. A combined analysis of these polymorphisms revealed that >90% of African American patients with late effects had at least 1 of these minor alleles, and 58% had 2 or more. No statistical significance was found relating the studied NOS3 polymorphisms and normal tissue toxicity.

CONCLUSIONS

These results support a strong association between wound repair and late toxicities of radiation. The presence of these genetic risk factors can vary significantly among different ethnic groups, as demonstrated for some of the SNPs. Future studies should account for the possibility of such ethnic heterogeneity in the late toxicities of radiation.

Pre-activation of mesenchymal stem cells with TNF-α, IL-1β and nitric oxide enhances its paracrine effects on radiation-induced intestinal injury

Conditioned medium from mesenchymal stem cells (MSC-CM) may represent a promising alternative to MSCs transplantation, however, the low concentrations of growth factors in non-activated MSC-CM hamper its clinical application. Recent data indicated that the paracrine potential of MSCs could be enhanced by inflammatory factors. Herein, we pre-activated bone-marrow-derived MSCs under radiation-induced inflammatory condition (MSC^IEC-6(IR)) and investigated the evidence and mechanism for the differential effects of MSC-CM^IEC-6(IR) and non-activated MSC-CM on radiation-induced intestinal injury (RIII). Systemic infusion of MSC-CM^IEC-6(IR), but not non-activated MSC-CM, dramatically improved intestinal damage and survival of irradiated rats. Such benefits may involve the modulation of epithelial regeneration and inflammation, as indicated by the regeneration of intestinal epithelial/stem cells, the regulation of the pro-/anti-inflammatory cytokine balance. The mechanism for the superior paracrine efficacy of MSC^IEC-6(IR) is related to a higher secretion of regenerative, immunomodulatory and trafficking molecules, including the pivotal factor IGF-1, induced by TNF-α, IL-1β and nitric oxide partially via a heme oxygenase-1 dependent mechanism. Together, our findings suggest that pre-activation of MSCs with TNF-α, IL-1β and nitric oxide enhances its paracine effects on RIII via a heme oxygenase-1 dependent mechanism, which may help us to maximize the paracrine potential of MSCs.

In vivo and in vitro effects of heme oxygenase-1 silencing on the survival of acute myelocytic leukemia-M2 cells

The aim of this study was to investigate the in vivo and in vitro effects of targeted heme oxygenase-1 (HO-1) silencing on the proliferation and apoptosis of human acute myelocytic leukemia (AML)-M2 cells. Bone marrow mononuclear cells (BMMNCs) were infected by pRNAi-siHO-1-GFP. The viability of the BMMNCs was determined by cell counting kit-8 (CCK-8) assay following daunorubicin (DNR) treatment. The apoptotic rate was detected by flow cytometry. The expression levels of HO-1 and apoptosis-related genes were detected by quantitative polymerase chain reaction (qPCR) and western blot analysis. An AML-M2 xenograft mouse model was established. The tumor formation outcomes and survival were observed. The leukocyte and platelet counts and hemoglobin levels were monitored, and the copy numbers of AML1/ETO fusion gene were detected by qPCR. pRNAi-siHO-1-GFP silenced the expression of HO-1. DNR inhibited cell viability in a time- and dose-dependent manner. The survival rate of the cells was significantly reduced by infection with pRNAi-siHO-1-GFP. HO-1 expression in the BMMNCs infected with pRNAi-siHO-1-GFP was downregulated, whereas caspase-3, -8 and -9 expression was upregulated compared with that in control BMMNCs. Kasumi-1 cells were successfully inoculated into nude mice. The rats inoculated with pRNAi-siHO-1-GFP-transfected Kasumi-1 cells succumbed to tumors more slowly and survived longer than those inoculated with untransfected Kasumi-1 cells. Furthermore, the leukocyte and platelet counts and hemoglobin levels were higher and the copy numbers of AML1/ETO fusion gene were lower in the former group. HO-1 gene silencing may promote the apoptosis of human M2 leukemic cells by inhibiting a caspase-dependent apoptotic pathway. Targeted silencing of HO-1 is able to inhibit the proliferation and infiltration of leukemic cells in nude mice and thus prolong their survival. The findings provide valuable experimental evidence for the molecular targeted therapy of M2 leukemia.

Dimethyl sulfoxide attenuates hydrogen peroxide-induced injury in cardiomyocytes via heme oxygenase-1

The antioxidant property of dimethyl sulfoxide (DMSO) was formerly attributed to its direct effects. Our former study showed that DMSO is able to induce heme oxygenase-1 (HO-1) expression in endothelial cells, which is a potent antioxidant enzyme. In this study, we hypothesized that the antioxidant effects of DMSO in cardiomyocytes are mediated or partially mediated by increased HO-1 expression. Therefore, we investigated whether DMSO exerts protective effects against H2 O2 -induced oxidative damage in cardiomyocytes, and whether HO-1 is involved in DMSO-imparted protective effects, and we also explore the underlying mechanism of DMSO-induced HO-1 expression. Our study demonstrated that DMSO pretreatment showed a cytoprotective effect against H2 O2 -induced oxidative damage (impaired cell viability, increased apopototic cells rate and caspase-3 level, and increased release of LDH and CK) and this process is partially mediated by HO-1 upregulation. Furthermore, our data showed that the activation of p38 MAPK and Nrf2 translocation are involved in the HO-1 upregulation induced by DMSO. This study reports for the first time that the cytoprotective effect of DMSO in cardiomyocytes is partially mediated by HO-1, which may further explain the mechanisms by which DMSO exerts cardioprotection on H2 O2 injury. J. Cell. Biochem. 115: 1159-1165, 2014. © 2013 Wiley Periodicals, Inc.

Effects of dietary arginine supplementation on growth performance, flesh quality, muscle antioxidant capacity and antioxidant-related signalling molecule expression in young grass carp (Ctenopharyngodon idella)

Growth performance, flesh quality, antioxidant status and antioxidant-related signalling molecule expression in the muscle of young grass carp, which were fed graded levels of arginine (6.9-24.5 g/kg diet) for eight weeks, were investigated. Muscle protein, lipid and nitric oxide contents, shear force, hydroxyproline concentration, and pH were significantly improved by appropriate arginine. Cooking loss, lactate content, cathepsins activities, malondialdehyde and protein carbonyl contents exhibited an opposite tendency. Additionally, optimum arginine significantly enhanced glutathione content and the activities and gene expression of copper/zinc superoxide dismutase, catalase and glutathione peroxidase in muscle. Moreover, the expression levels of glutamate-cysteine ligase, target of rapamycin, ribosome protein S6 kinase 1, casein kinase 2 and NF-E2-related factor 2 in muscle were significantly elevated by appropriate arginine. However, optimum arginine significantly decreased Kelch-like ECH-associated protein 1 mRNA levels in muscle. In conclusion, arginine improved the flesh quality and muscle antioxidant capacity and regulated antioxidant-related signalling molecule expression.

Combinative effects of thanh hao miet giap thang (sweet wormwood and tortoise shell decoction) ingredients on antioxidative activity in vitro

BACKGROUND

Traditional formulae usually exhibit therapeutic effects through the combinations of different ingredients. The purpose of this study was to investigate in vitro anti-oxidative activity of Thanh Hao Miet Giap Thang (THMGT) (Sweet Wormwood and Tortoise Shell Decoction) formula and the interactions of its ingredients leading to the overall anti-oxidative effect.

MATERIALS AND METHODS

We prepared 31 combinations containing two to four of the five ingredients including Herba Artemisia apiacea L (HbA), Carapax Trionycis (Tryonix sinensis) (CT), Rhizoma Anemarrhenae (Anemarrhena asphodeloides) (RzA), Radix Rehmanniae (Rehmannia glutinosa Libosch) (RdR), Moutan Cortex (Paeonia suffruticosa) (MC). These combinations were tested for anti-oxidative activity using DCFH-DA and DPPH assays on Hep G2 cells. We also analyzed changes in expression of genes involved in antioxidant defense system including Nuclear Factor Erythroid-Derived 2-Like 2 (NFE2L2), catalase (CAT), heme oxygenase-1 (HO-1), glutathione peroxidase (GPx), cytoplasmic superoxide dismutase (SOD1), mitochondrial superoxide dismutase (SOD2).

RESULTS

The complete formula and all combinations containing Moutan Cortex showed high antioxidant activity in both radical solution-based chemical assay and cellular-based assay. On the contrary, Carapax Trionycis displayed inhibitory effect on the overall antioxidant activity when present in a combination, an effect clearly emphasized in cellular-based assay. Hep G2 cells treated with the formula showed increased gene expression of HO-1 and SOD2 while expression of CAT, SOD1, GPx was unchanged.

CONCLUSION

Our results suggested that THMGT had anti-oxidative activity essentially through intrinsic reducing capacities and the overall activity of the formula resulted from enhancing and inhibiting interactions of ingredients.

The complex interplay of iron metabolism, reactive oxygen species, and reactive nitrogen species: insights into the potential of various iron therapies to induce oxidative and nitrosative stress

Production of minute concentrations of superoxide (O2(*-)) and nitrogen monoxide (nitric oxide, NO*) plays important roles in several aspects of cellular signaling and metabolic regulation. However, in an inflammatory environment, the concentrations of these radicals can drastically increase and the antioxidant defenses may become overwhelmed. Thus, biological damage may occur owing to redox imbalance-a condition called oxidative and/or nitrosative stress. A complex interplay exists between iron metabolism, O2(*-), hydrogen peroxide (H2O2), and NO*. Iron is involved in both the formation and the scavenging of these species. Iron deficiency (anemia) (ID(A)) is associated with oxidative stress, but its role in the induction of nitrosative stress is largely unclear. Moreover, oral as well as intravenous (iv) iron preparations used for the treatment of ID(A) may also induce oxidative and/or nitrosative stress. Oral administration of ferrous salts may lead to high transferrin saturation levels and, thus, formation of non-transferrin-bound iron, a potentially toxic form of iron with a propensity to induce oxidative stress. One of the factors that determine the likelihood of oxidative and nitrosative stress induced upon administration of an iv iron complex is the amount of labile (or weakly-bound) iron present in the complex. Stable dextran-based iron complexes used for iv therapy, although they contain only negligible amounts of labile iron, can induce oxidative and/or nitrosative stress through so far unknown mechanisms. In this review, after summarizing the main features of iron metabolism and its complex interplay with O2(*-), H2O2, NO*, and other more reactive compounds derived from these species, the potential of various iron therapies to induce oxidative and nitrosative stress is discussed and possible underlying mechanisms are proposed. Understanding the mechanisms, by which various iron formulations may induce oxidative and nitrosative stress, will help us develop better tolerated and more efficient therapies for various dysfunctions of iron metabolism.

Lipoxin A4-induced heme oxygenase-1 protects cardiomyocytes against hypoxia/reoxygenation injury via p38 MAPK activation and Nrf2/ARE complex

OBJECTIVE

To investigate whether lipoxin A4 (LXA4) increases expression of heme oxygenase-1(HO-1) in cardiomyocytes, whether LXA4-induced HO-1 protects cardiomyocytes against hypoxia/reoxygenation (H/R) injury, and what are the mechanisms involved in the LXA4-induced HO-1 induction.

METHODS

Rat cardiomyocytes were exposed to H/R injury with or without preincubation with LXA4 or HO-1 inhibitor ZnPP-IX or various signal molecule inhibitors. Expressions of HO-1 protein and mRNA were analyzed by using Western blot and RT-PCR respectively. Activity of nuclear factor E2-related factor 2 (Nrf2) binding to the HO-1 E1 enhancer was assessed by chromatin immunoprecipitation. Nrf2 binding to the HO-1 antioxidant responsive element (ARE) were measured by using electrophoretic mobility shift assay.

RESULTS

Pretreatment of the cells undergoing H/R lesion with LXA4 significantly reduced the lactate dehydrogenase and creatine kinase productions, increased the cell viability, and increased the expressions of HO-1 protein and mRNA and HO-1 promoter activity. HO-1 inhibition abolished the protective role of LXA4 on the cells undergoing H/R lesion. LXA4 increased p38 mitogen-activated protein kinase (p38 MAPK) activation, nuclear translocation of Nrf2, Nrf2 binding to the HO-1 ARE and E1 enhancer in cardiomyocytes with or without H/R exposure.

CONCLUSION

The protection role of LXA4 against H/R injury of cardiomyocytes is related to upregulation of HO-1, via activation of p38 MAPK pathway and nuclear translocation of Nrf2 and Nrf2 binding to the HO-1 ARE and E1 enhancer, but not via activation of phosphatidyinositol-3-kinase or extracellular signal-regulated kinase pathway.

Physiological cyclic strain promotes endothelial cell survival via the induction of heme oxygenase-1

Endothelial cells (ECs) are constantly subjected to cyclic strain that arises from periodic change in vessel wall diameter as a result of pulsatile blood flow. Application of physiological levels of cyclic strain inhibits EC apoptosis; however, the underlying mechanism is not known. Since heme oxygenase-1 (HO-1) is a potent inhibitor of apoptosis, the present study investigated whether HO-1 contributes to the antiapoptotic action of cyclic strain. Administration of physiological cyclic strain (6% at 1 Hz) to human aortic ECs stimulated an increase in HO-1 activity, protein, and mRNA expression. The induction of HO-1 was preceded by a rise in reactive oxygen species (ROS) and Nrf2 protein expression. Cyclic strain also stimulated an increase in HO-1 promoter activity that was prevented by mutating the antioxidant responsive element in the promoter or by overexpressing dominant-negative Nrf2. In addition, the strain-mediated induction of HO-1 and activation of Nrf2 was abolished by the antioxidant N-acetyl-l-cysteine. Finally, application of cyclic strain blocked inflammatory cytokine-mediated EC death and apoptosis. However, the protective action of cyclic strain was reversed by the HO inhibitor tin protoporphyrin-IX and was absent in ECs isolated from HO-1-deficient mice. In conclusion, the present study demonstrates that a hemodynamically relevant level of cyclic strain stimulates HO-1 gene expression in ECs via the ROS-Nrf2 signaling pathway to inhibit EC death. The ability of cyclic strain to induce HO-1 expression may provide an important mechanism by which hemodynamic forces promote EC survival and vascular homeostasis.

IL-17 induces expression of vascular cell adhesion molecule through signalling pathway of NF-κB, but not Akt1 and TAK1 in vascular smooth muscle cells

Interleukin-17 (IL-17) plays an important role in several autoimmune diseases. IL-17 can induce the expression of vascular cell adhesion molecule (VCAM-1) in aortic vascular smooth muscle cells (SMCs), which is important for the development of atherosclerosis. However, the signalling pathway of IL-17-induced VCAM-1 expression remains unclear. In this study, we reported that IL-17-induced expression of VCAM-1 in SMCs is dependent on NF-κB, but independent of Akt1 and TAK1. This is because knocking down Akt1 or TAK1 by siRNA did not reduce IL-17-induced activation of NF-κB and expression of VCAM-1, whereas knocking down NF-κB by siRNA markedly inhibited IL-17-mediated upregulation of VCAM-1 expression. In addition, IL-17-induced expression of VCAM-1 is partially dependent on activation of ERK1/2. Therefore, these signalling pathways of IL-17-mediated upregulation of VCAM-1 expression might be therapeutic targets for treatment of IL-17-mediated inflammation.