Peroxiredoxin I is a ROS/p38 MAPK-dependent inducible antioxidant that regulates NF-κB-mediated iNOS induction and microglial activation

Functional characterization of peroxiredoxin 5 from yellowtail clownfish (Amphiprion clarkii): Immunological expression assessment, antioxidant activities, heavy metal detoxification, and nitrosative stress mitigation

Peroxiredoxin 5 (Prdx5) is the last recognized member of Prdx family. It is a unique, atypical, 2-Cys antioxidant enzyme, protecting cells from death caused by reactive oxygen species (ROS). In this study, the Prdx5 ortholog of Amphiprion clarkii (AcPrdx5) was identified and characterized to explore its specific structural features and functional properties. The open reading frame of AcPrdx5 is 573 bp long and encodes 190 amino acids containing a mitochondrial targeting sequence, thioredoxin domain, and two conserved cysteine residues responsible for antioxidant function. The predicted molecular weight and theoretical isoelectric point of AcPrdx5 are 20.3 kDa and 9.01, respectively. AcPrdx5 sequences were found to be highly conserved across the other orthologs from various organisms and it distinctively clustered within the fish Prdx5 subclade of the phylogenetic tree. The expression of AcPrdx5 was ubiquitously detected among twelve tested tissues, with the highest level in the brain. Furthermore, the mRNA levels of AcPrdx5 in the blood and head-kidney tissues were significantly (p < 0.05) upregulated following polyinosinic-polycytidylic acid (Poly I:C), lipopolysaccharide (LPS), and Vibrio harveyi immune challenge. A concentration-dependent antioxidant potential of recombinant AcPrdx5 was observed in insulin disulfide bond reduction, heavy metal detoxification, free radical and hydrogen peroxide (H2O2) scavenging assays. Additionally, AcPrdx5 overexpression in fathead minnow (FHM) cells upregulated the antioxidant-associated gene (Rrm1, MAPK, SOD2, and PRDX1) expression after H2O2 treatment, and promoted cell viability upon arsenic (As) exposure. In macrophages, AcPrdx5 overexpression effectively suppressed substantial nitric oxide production under lipopolysaccharide treatment. Collectively, our results suggest that AcPrdx5 may play roles in both antioxidant defense system and innate immune response against pathogenic invasions in A. clarkii.

Unraveling the ozone impact and oxidative stress on the nervous system

Ozone (O₃), a potent oxidant, can penetrate the body through breathing, generating reactive oxygen species (ROS) and triggering inflammatory processes. Oxidative stress, an imbalance between the production of ROS and the body's antioxidant capacity, plays a crucial role in the pathophysiology of various neurodegenerative diseases. This phenomenon can negatively impact the Central Nervous System (CNS), inducing structural and functional alterations that contribute to the development of neurological pathologies. This review examines how O₃-induced oxidative stress affects the nervous system by analyzing existing literature on the involved molecular mechanisms and potential antioxidant systems to mitigate its effects. Through a comprehensive review of experimental studies, our objective is to shed light on the interaction between O₃ and the nervous system, as well as its signaling pathways and altered genes, providing a foundation for future research in this field. Several studies have demonstrated that prolonged exposure to O₃ leads to increased expression of reactive oxygen species, causing alterations in the blood-brain barrier and damage to astrocytes and microglia. These effects can lead to an increase in the production of proinflammatory cytokines, neurotoxins, and genes, exacerbating neuronal damage and accelerating the progression of neurodegenerative diseases such as Alzheimer's, Parkinson's, and other neurological disorders. The results of this review suggest that exposure to O₃ may induce oxidative damage to the nervous system, which could have significant implications for public health.

Oxyresveratrol reduces lipopolysaccharide-induced inflammation and oxidative stress through inactivation of MAPK and NF-κB signaling in brain endothelial cells

Inflammatory responses and oxidative stress damage the integrity of the blood-brain barrier (BBB), which is a primary pathological modulator of neurodegenerative diseases. Brain endothelial cells are crucial components of BBB. In the present study, the effect of oxyresveratrol on lipopolysaccharide (LPS)-induced brain endothelial (bEnd.3) cells was assessed. Our results showed that oxyresveratrol diminished protein expressions of inducible nitric oxide synthase (iNOS) and adhesion molecules including intercellular adhesion molecule (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1), nitric oxide (NO) production, and proinflammatory cytokines such as interleukin-6 (IL-6) and tumor necrosis factor (TNF-α) in LPS-elicited bEnd.3 cells. These anti-inflammatory effects were mediated through suppressing nuclear factor-kappa B (NF-κB) and mitogen-activated protein kinase (MAPK) signaling pathways. In addition, we found that oxyresveratrol reduced reactive oxygen species (ROS) levels. To conclude, the current results demonstrated the protective role of oxyresveratrol against LPS-induced inflammation and oxidative stress in bEnd.3 cells, suggesting its potential effect for mitigating neurodegenerative and cerebrovascular diseases.

NOX2 Enzyme Mimicking Nano-Networks Regulate Tumor-Associated Macrophages to Initiate Both Innate and Adaptive Immune Effects

Macrophages, capable of both direct killing and antigen presentation, are crucial for the interplay between innate and adaptive immunity. However, strategies mainly focus on polarizing tumor-associated macrophages (TAMs) to M1 phenotype, while overlooking the inefficient antigen cross-presentation due to hyperactive hydrolytic protease within lysosomes which leads to antigen degradation. In light of the significant influence of reactive oxygen species (ROS) on TAMs' polarization and the inhibition of phagosomal proteolysis, a novel nanosystem termed OVA-Fe-GA (OFG) is engineered, drawing inspiration from the NOX2 enzyme's role. OFG integrates ovalbumin (OVA) and a network composed of Fe-gallic acid (GA), emulating the NOX2 enzyme's sequential ROS generation process ("O2 to O2 •- to H2O2/•OH"). Furthermore, it elucidates a biological mechanism that augments antigen cross-presentation by suppressing the expression of cysteine proteases. OFG restores the innate anti-tumor functionality of TAMs and significantly amplifies their antigen cross-presentation (4.5-fold compared to the PBS control group) in B16-OVA tumor-bearing mice. Notably, the infiltration and activity of intratumoral CD8+ T cells are enhanced, indicating an adaptive immune response. Moreover, OFG exhibits excellent photothermal properties, thereby fostering a system antitumor immune response. This study provides a promising strategy for initiating both innate and adaptive immunity via TAMs activation.

Peroxiredoxin 1 inhibits streptozotocin-induced Alzheimer's disease-like pathology in hippocampal neuronal cells via the blocking of Ca2+/Calpain/Cdk5-mediated mitochondrial fragmentation

Oxidative stress plays an essential role in the progression of Alzheimer's disease (AD), the most common age-related neurodegenerative disorder. Streptozotocin (STZ)-induced abnormal brain insulin signaling and oxidative stress play crucial roles in the progression of Alzheimer's disease (AD)-like pathology. Peroxiredoxins (Prxs) are associated with protection from neuronal death induced by oxidative stress. However, the molecular mechanisms underlying Prxs on STZ-induced progression of AD in the hippocampal neurons are not yet fully understood. Here, we evaluated whether Peroxiredoxin 1 (Prx1) affects STZ-induced AD-like pathology and cellular toxicity. Prx1 expression was increased by STZ treatment in the hippocampus cell line, HT-22 cells. We evaluated whether Prx1 affects STZ-induced HT-22 cells using overexpression. Prx1 successfully protected the forms of STZ-induced AD-like pathology, such as neuronal apoptosis, synaptic loss, and tau phosphorylation. Moreover, Prx1 suppressed the STZ-induced increase of mitochondrial dysfunction and fragmentation by down-regulating Drp1 phosphorylation and mitochondrial location. Prx1 plays a role in an upstream signal pathway of Drp1 phosphorylation, cyclin-dependent kinase 5 (Cdk5) by inhibiting the STZ-induced conversion of p35 to p25. We found that STZ-induced of intracellular Ca2+ accumulation was an important modulator of AD-like pathology progression by regulating Ca2+-mediated Calpain activation, and Prx1 down-regulated STZ-induced intracellular Ca2+ accumulation and Ca2+-mediated Calpain activation. Finally, we identified that Prx1 antioxidant capacity affected Ca2+/Calpain/Cdk5-mediated AD-like pathology progress. Therefore, these findings demonstrated that Prx1 is a key factor in STZ-induced hippocampal neuronal death through inhibition of Ca2+/Calpain/Cdk5-mediated mitochondrial dysfunction by protecting against oxidative stress.

Molecular characterization, cytoprotective, DNA protective, and immunological assessment of peroxiredoxin-1 (Prdx1) from yellowtail clownfish (Amphiprion clarkii)

Peroxiredoxin-1 (Prdx1) is a thiol-specific antioxidant enzyme that detoxifies reactive oxygen species (ROS) and regulates the redox status of cells. In this study, the Prdx1 cDNA sequence was isolated from the pre-established Amphiprion clarkii (A. clarkii) (AcPrdx1) transcriptome database and characterized structurally and functionally. The AcPrdx1 coding sequence comprises 597 bp and encodes 198 amino acids with a molecular weight of 22.1 kDa and a predicted theoretical isoelectric point of 6.3. AcPrdx1 is localized and functionally available in the cytoplasm and nucleus of cells. The TXN domain of AcPrdx1 comprises two peroxiredoxin signature VCP motifs, which contain catalytic peroxidatic (Cp-C52) and resolving cysteine (CR-C173) residues. The constructed phylogenetic tree and sequence alignment revealed that AcPrdx1 is evolutionarily conserved, and its most closely related counterpart is Amphiprion ocellaris. Under normal physiological conditions, AcPrdx1 was ubiquitously detected in all tissues examined, with the most robust expression in the spleen. Furthermore, AcPrdx1 transcripts were significantly upregulated in the spleen, head kidney, and blood after immune stimulation by polyinosinic:polycytidylic acid (poly (I:C)), lipopolysaccharide (LPS), and Vibrio harveyi injection. Recombinant AcPrdx1 (rAcPrdx1) demonstrated antioxidant and DNA protective properties in a concentration-dependent manner, as evidenced by insulin disulfide reduction, peroxidase activity, and metal-catalyzed oxidation (MCO) assays, whereas cells transfected with pcDNA3.1(+)/AcPrdx1 showed significant cytoprotective function under oxidative and nitrosative stress. Overexpression of AcPrdx1 in fathead minnow (FHM) cells led to a lower viral copy number following viral hemorrhagic septicemia virus (VHSV) infection, along with upregulation of several antiviral genes. Collectively, this study provides insights into the function of AcPrdx1 in defense against oxidative stressors and its role in the immune response against pathogenic infections in A. clarkii.

Laminin-Augmented Decellularized Extracellular Matrix Ameliorating Neural Differentiation and Neuroinflammation in Human Mini-Brains

Non-neural extracellular matrix (ECM) has limited application in humanized physiological neural modeling due to insufficient brain-specificity and safety concerns. Although brain-derived ECM contains enriched neural components, certain essential components are partially lost during the decellularization process, necessitating augmentation. Here, it is demonstrated that the laminin-augmented porcine brain-decellularized ECM (P-BdECM) is xenogeneic factor-depleted as well as favorable for the regulation of human neurons, astrocytes, and microglia. P-BdECM composition is comparable to human BdECM regarding brain-specificity through the matrisome and gene ontology-biological process analysis. As augmenting strategy, laminin 111 supplement promotes neural function by synergic effect with laminin 521 in P-BdECM. Annexin A1(ANXA1) and Peroxiredoxin(PRDX) in P-BdECM stabilized microglial and astrocytic behavior under normal while promoting active neuroinflammation in response to neuropathological factors. Further, supplementation of the brain-specific molecule to non-neural matrix also ameliorated glial cell inflammation as in P-BdECM. In conclusion, P-BdECM-augmentation strategy can be used to recapitulate humanized pathophysiological cerebral environments for neurological study.

Selective Manipulation of the Mitochondria Oxidative Stress in Different Cells Using Intelligent Mesoporous Silica Nanoparticles to Activate On-Demand Immunotherapy for Cancer Treatment

Herein, the vitamin K2 (VK2)/maleimide (MA) coloaded mesoporous silica nanoparticles (MSNs), functional molecules including folic acid (FA)/triphenylphosphine (TPP)/tetrapotassium hexacyanoferrate trihydrate (THT), as well as CaCO3 are explored to fabricate a core-shell-corona nanoparticle (VMMFTTC) for on-demand anti-tumor immunotherapy. After application, the tumor-specific acidic environment first decomposed CaCO3 corona, which significantly levitates the pH value of tumor tissue to convert M2 type macrophage to the antitumor M1 type. The resulting VMMFTT would then internalize in both tumor cells and macrophages via FA-assisted endocytosis and free endocytosis, respectively. These distinct processes generate different amount of VMMFTT in above two cells followed by 1) TPP-induced accumulation in the mitochondria, 2) THT-mediated effective capture of various signal ions to cut off signal transmission and further inhibit glutathione (GSH) generation, 3) ions catalyzed reactive oxygen species (ROS) production through Fenton reaction, 4) sustained release of VK2 and MA to further enhance the ROS production and GSH depletion, which caused significant apoptosis of tumor cells and additional M2-to-M1 macrophage polarization via different processes of oxidative stress. Moreover, the primary tumor apoptosis further matures surrounding immature dendritic cells and activates T cells to continuously promote the antitumor immunotherapy.

TDP43/HDAC6/Prdx1 signaling pathway participated in the cognitive impairment of obstructive sleep apnea via regulating inflammation and oxidative stress

Neuroinflammation and oxidative stress induced by intermittent hypoxia (IH) are associated with cognitive dysfunction in patients with obstructive sleep apnea (OSA). Recently, TAR DNA-binding protein 43 (TDP-43), histone deacetylase 6 (HDAC6), and peroxiredoxin 1 (Prdx1) have been reported to be involved in cognitive impairment in many degenerative diseases; however, the underlying mechanisms remain unclear. In the present study, subjects underwent polysomnography to diagnose OSA. Cognitive function was evaluated using the Montreal Cognitive Assessment (MoCA) and peripheral blood samples were collected. HMC3 cells were treated with lipopolysaccharide (LPS) to mimic in vitro neuroinflammation. Western blotting was used to assess protein expression and ELISA to assess inflammation and oxidative stress levels. Participants were divided into three groups: healthy control (n = 20); mild to moderate OSA (n = 20); and severe OSA (n = 20). The MoCA scores in mild-moderate OSA and severe OSA were lower than those in healthy controls. Continuous positive airway pressure therapy was found to be effective for cognitive impairment in subjects with severe OSA (24.70 ± 1.81). Expression of TDP-43 and HDAC6 was increased in subjects with OSA, whereas Prdx1 expression was decreased. Alterations in these proteins were partially reversed after 12 weeks of CPAP treatment. Protein expression of TDP-43 and HDAC6 was negatively correlated with MoCA scores in patients with OSA, while Prdx1 expression exhibited the opposite trend. In LPS-treated HMC3 cells, TDP-43 and HDAC6 were upregulated, whereas Prdx1 expression was reduced. TDP-43 influenced the expression of Prdx1 by regulating HDAC6, and inflammation and oxidative stress varied with the expression of TDP-43. When a specific inhibitor of HDAC6 was used, LPS-induced inflammation and oxidative stress were alleviated by an elevated level of Prdx1. In summary, findings of the present study suggest that TDP-43 influenced Prdx1 by regulating HDAC6 expression and promoting neuroinflammation and oxidative stress. This process may be involved in the cognitive impairment experienced by patients with OSA and may provide potential therapeutic targets.

Behavioral and histological assessment of a novel treatment of neuroHIV in humanized mice

Neurocognitive deficits are prevalent among people living with HIV, likely due to chronic inflammation and oxidative stress in the brain. To date, no pharmaceutical treatments beyond antiretroviral therapy (ARV) has been shown to reduce risk for, or severity of, HIV-associated neurocognitive disorder. Here we investigate a novel compound, CDDO-Me, with documented neuroprotective effects via activation of the nrf2 and inhibition of the NFkB pathways.

Methods

We conducted three studies to assess the efficacy of CDDO-Me alone or in combination with antiretroviral therapy in humanized mice infected with HIV; behavioral, histopathological, and immunohistochemical.

Results

CDDO-Me in combination with ARV rescued social interaction deficits; however, only ARV was associated with preserved functioning in other behaviors, and CDDO-Me may have attenuated those benefits. A modest neuroprotective effect was found for CDDO-Me when administered with ARV, via preservation of PSD-95 expression; however, ARV alone had a more consistent protective effect. No significant changes in antioxidant enzyme expression levels were observed in CDDO-Me-treated animals. Only ARV use seemed to affect some antioxidant levels, indicating that it is ARV rather than CDDO-Me that is the major factor providing neuroprotection in this animal model. Finally, immunohistochemical analysis found that several cellular markers in various brain regions varied due to ARV rather than CDDO-Me.

Conclusion

Limited benefit of CDDO-Me on behavior and neuroprotection were observed. Instead, ARV was shown to be the more beneficial treatment. These experiments support the future use of this chimeric mouse for behavioral experiments in neuroHIV research.

OsLPXC negatively regulates tolerance to cold stress via modulating oxidative stress, antioxidant defense and JA accumulation in rice

Exposure of crops to low temperature (LT) during emerging and reproductive stages influences their growth and development. In this study, we have isolated a cold induced, nucleus-localized lipid A gene from rice named OsLPXC, which encodes a protein of 321 amino acids. Knockout of OsLPXC resulted in enhance sensitivity to LT stress in rice, with increased accumulation of reactive oxygen species (ROS), malondialdehyde and electrolyte leakage, while expression and activities of antioxidant enzymes were significantly suppressed. The accumulation of chlorophyll content and net photosynthetic rate of knockout plants were also decreased compared with WT under LT stress. The functional analysis of differentially expressed genes (DEGs), showed that numerous genes associated with antioxidant defense, photosynthesis, cold signaling were solely expressed and downregulated in oslpxc plants compared with WT under LT. The accumulation of methyl jasmonate (MeJA) in leave and several DEGs related to the jasmonate biosynthesis pathway were significantly downregulated in OsLPXC knockout plants, which showed differential levels of MeJA regulation in WT and knockout plants in response to cold stress. These results indicated that OsLPXC positively regulates cold tolerance in rice via stabilizing the expression and activities of ROS scavenging enzymes, photosynthetic apparatus, cold signaling genes, and jasmonate biosynthesis.

Molecular characterization, immune expression, and functional delineation of peroxiredoxin 1 in Epinephelus akaara

Peroxiredoxin 1 is a member of the typical 2-Cys peroxiredoxin family, which serves diverse functions in gene expression, immune and inflammatory responses, and tumor progression. In this study, we aimed to analyze the structural, functional, and immunomodulatory properties of peroxiredoxin 1 from Epinephelus akaara (EaPrx1). The open reading frame of EaPrx1 is 597 base pairs in length, encoding 198 amino acids, with a molecular weight of approximately 22 kDa. The in silico analysis revealed that EaPrx1 shares a conserved thioredoxin fold and signature motifs that are critical for its catalytic activity and oligomerization. Further, EaPrx1 is closely related to Epinephelus lanceolatus Prx1 and clustered in the Fishes group of the vertebrate clade, revealing that EaPrx1 was conserved throughout evolution. In terms of tissue distribution, a high level of EaPrx1 expression was observed in the spleen, brain, and blood tissues. Likewise, in immune challenge experiments, significant transcriptional modulations of EaPrx1 upon lipopolysaccharide, polyinosinic:polycytidylic acid, and nervous necrosis virus injections were noted at different time points, indicating the immunological role of EaPrx1 against pathogenic infections. In the functional analysis, rEaPrx1 exhibited substantial DNA protection, insulin disulfide reduction, and tissue repair activities, which were concentration-dependent. EaPrx1/pcDNA™ 3.1 (+)-transfected fathead minnow cells revealed high cell viability upon arsenic toxicity, indicating the heavy metal detoxification activity of EaPrx1. Taken together, the transcriptional and functional studies imply critical roles of EaPrx1 in innate immunity, redox regulation, apoptosis, and tissue-repair processes in E. akaara.

Redox signaling at the crossroads of human health and disease

Redox biology is at the core of life sciences, accompanied by the close correlation of redox processes with biological activities. Redox homeostasis is a prerequisite for human health, in which the physiological levels of nonradical reactive oxygen species (ROS) function as the primary second messengers to modulate physiological redox signaling by orchestrating multiple redox sensors. However, excessive ROS accumulation, termed oxidative stress (OS), leads to biomolecule damage and subsequent occurrence of various diseases such as type 2 diabetes, atherosclerosis, and cancer. Herein, starting with the evolution of redox biology, we reveal the roles of ROS as multifaceted physiological modulators to mediate redox signaling and sustain redox homeostasis. In addition, we also emphasize the detailed OS mechanisms involved in the initiation and development of several important diseases. ROS as a double-edged sword in disease progression suggest two different therapeutic strategies to treat redox-relevant diseases, in which targeting ROS sources and redox-related effectors to manipulate redox homeostasis will largely promote precision medicine. Therefore, a comprehensive understanding of the redox signaling networks under physiological and pathological conditions will facilitate the development of redox medicine and benefit patients with redox-relevant diseases.

Stem cell-derived exosomes and copper sulfide nanoparticles attenuate the progression of neurodegenerative disorders induced by cadmium in rats

The goal of the current study was to investigate the therapeutic effects of exosomes derived from mesenchymal stem cells (MSCs-Exo) and copper sulfide nanoparticles (CuSNPs) as biomaterials in order to understand the mechanisms that contribute to overcoming cadmium (Cad) induced neurological disorders in rats. Animals were divided into five groups (n = 10): group 1 was served as a negative control and receive vehicle saline (Con), group 2 Positive control groups were received Cad as cadmium chloride at a dose of 20 mg/kg/day for six weeks (Cad group), group 3 was received Cad plus MSCs-Exo as a single dose of 100 μLi. v. (Cad + MSCs-Exo), group 4 was received Cad plus CuSNPs at a dose of 6.5 mg/kg orally (Cad + CuSNPs), group 5 was received Cad + MSCs-Exo + CuSNPs for six weeks. However, the activities of each acetylcholine (Ach), acetylcholinesterase (AchE), total antioxidant status (TAC) were measured. Also, the levels of ROS, nuclear factor kappa B (NF-κB), tumor necrosis factor-α (TNF-α), Brain brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) were evaluated. Beneficial effects on the behavior of animals were observed after treatment with MSCs-Exo and CuSNPs. Furthermore, the administration of MSCs-Exo and CuSNPs have been improve the TAC, BDNF and NGF via ameliorating the oxidative stress and inflammatory markers. Moreover, Histopathological studies had shown that great development in the brain of Cad rats treated with MSCs-Exo and CuSNPs. In conclusion, this study offers an overview of innovative stem cell therapy techniques and how to integrate them with nanotechnology to boost therapeutic performance.

Na+/Ca2+ exchanger isoform 1 takes part to the Ca2+-related prosurvival pathway of SOD1 in primary motor neurons exposed to beta-methylamino-L-alanine

Background

The cycad neurotoxin beta-methylamino-l-alanine (L-BMAA), one of the environmental trigger factor for amyotrophic lateral sclerosis/Parkinson-dementia complex (ALS/PDC), may cause neurodegeneration by disrupting organellar Ca²⁺ homeostasis. Through the activation of Akt/ERK1/2 pathway, the Cu,Zn-superoxide dismutase (SOD1) and its non-metallated form, ApoSOD1, prevent endoplasmic reticulum (ER) stress-induced cell death in motor neurons exposed to L-BMAA. This occurs through the rapid increase of intracellular Ca²⁺ concentration ([Ca²⁺]_i) in part flowing from the extracellular compartment and in part released from ER. However, the molecular components of this mechanism remain uncharacterized.

Methods

By an integrated approach consisting on the use of siRNA strategy, Western blotting, confocal double- labeling immunofluorescence, patch-clamp electrophysiology, and Fura 2-/SBFI-single-cell imaging, we explored in rat motor neuron-enriched cultures the involvement of the plasma membrane proteins Na⁺/Ca²⁺ exchanger (NCX) and purinergic P₂X₇ receptor as well as that of the intracellular cADP-ribose (cADPR) pathway, in the neuroprotective mechanism of SOD1.

Results

We showed that SOD1-induced [Ca²⁺]_i rise was prevented neither by A430879, a P₂X₇ receptor specific antagonist or 8-bromo-cADPR, a cell permeant antagonist of cADP-ribose, but only by the pan inhibitor of NCX, CB-DMB. The same occurred for the ApoSOD1. Confocal double labeling immunofluorescence showed a huge expression of plasmalemmal NCX1 and intracellular NCX3 isoforms. Furthermore, we identified NCX1 reverse mode as the main mechanism responsible for the neuroprotective ER Ca²⁺ refilling elicited by SOD1 and ApoSOD1 through which they promoted translocation of active Akt in the nuclei of a subset of primary motor neurons. Finally, the activation of NCX1 by the specific agonist CN-PYB2 protected motor neurons from L-BMAA-induced cell death, mimicking the effect of SOD1.

Conclusion

Collectively, our data indicate that SOD1 and ApoSOD1 exert their neuroprotective effect by modulating ER Ca²⁺ content through the activation of NCX1 reverse mode and Akt nuclear translocation in a subset of primary motor neurons.

The Role of Oxidative Stress in Intervertebral Disc Degeneration

Intervertebral disc degeneration is a very common type of degenerative disease causing severe socioeconomic impact, as well as a major cause of discogenic low back pain and herniated discs, placing a heavy burden on patients and the clinicians who treat them. IDD is known to be associating with a complex process involving in extracellular matrix and cellular damage, and in recent years, there is increasing evidence that oxidative stress is an important activation mechanism of IDD and that reactive oxygen and reactive nitrogen species regulate matrix metabolism, proinflammatory phenotype, autophagy and senescence in intervertebral disc cells, apoptosis, autophagy, and senescence. Despite the tremendous efforts of researchers within the field of IDD pathogenesis, the proven strategies to prevent and treat this disease are still very limited. Up to now, several antioxidants have been proved to be effective for alleviating IDD. In this article, we discussed that oxidative stress accelerates disc degeneration by influencing aging, inflammation, autophagy, and DNA methylation, and summarize some antioxidant therapeutic measures for IDD, indicating that antioxidant therapy for disc degeneration holds excellent promise.

Peroxiredoxin 1 Controls Ovulation and Ovulated Cumulus-Oocyte Complex Activity through TLR4-Derived ERK1/2 Signaling in Mice

Peroxiredoxins (PRDXs) are expressed in the ovary and during ovulation. PRDX1 activity related to the immuno-like response during ovulation is unknown. We investigated the roles of Prdx1 on TLR4 and ERK1/2 signaling from the ovulated cumulus–oocyte complex (COC) using Prdx1-knockout (K/O) and wild-type (WT) mice. Ovulated COCs were collected 12 and 16 h after pregnant mare serum gonadotropin/hCG injection. PRDX1 protein expression and COC secretion factors (Il-6, Tnfaip6, and Ptgs2) increased 16 h after ovulated COCs of the WT mice were obtained. We treated the ovulated COCs in mice with LPS (0.5 μg/mL) or hyaluronidase (Hya) (10 units/mL) to induce TLR4 activity. Intracellular reactive oxygen species (ROS), cumulus cell apoptosis, PRDX1, TLR4/P38/ERK1/2 protein expression, and COC secretion factors’ mRNA levels increased in LPS- and Hya-treated COCs. The ERK inhibitor (U0126) and Prdx1 siRNA affected TLR4/ERK1/2 expression. The number and cumulus expansion of ovulated COCs by ROS were impaired in Prdx1 K/O mice but not in WT ones. Prdx1 gene deletion induced TLR4/P38/ERK1/2 expression and cumulus expansion genes. These results show the controlling roles of PRDX1 for TLR4/P38/ERK1/2 signaling activity in ovulated mice and the interlink of COCs with ovulation.

Filtration of Active Components with Antioxidant Activity Based on the Differing Antioxidant Abilities of Schisandrae Sphenantherae Fructus and Schisandrae Chinensis Fructus through UPLC/MS Coupling with Network Pharmacology

This study attempted to filter active components with antioxidant activities based on the differing antioxidant abilities of Schisandrae Sphenantherae Fructus (SSF) and Schisandrae Chinensis Fructus (SCF). First, the antioxidant activity of SSF and SCF was evaluated through the DPPH free radical scavenging method and compared with the half maximal inhibitory concentration (IC₅₀) value. Next, components of SSF and SCF were detected by employing ultrahigh-performance liquid chromatography-Q-Exactive Orbitrap mass spectrometry (UPLC-QEO/MS) technology, and differential compounds were screened out as potential antioxidant compounds by using Compound Discover 3.1 Software. After that step, in order to verify the antioxidant compounds, the network method was applied. Biological targets were searched in the GeneCards database, and that related to antioxidant ability were selected in the Comparative Toxicogenomics Database (CTD). Finally, the pharmacology network was constructed. Results showed that SSF and SCF possessed different compounds and antioxidant abilities. A total of 14 differential compounds such as γ-schizandrin, schisandrin B, schisandrin, and tigloylgomisin H between them were screened out and identified. Twenty targets associated with antioxidant activity contained MAP2K1, MAPK8, RPS6KB1, PRKCB, HIF1A, and so on were investigated. Thirty-six pathways contained HIF-1 signaling pathways, choline metabolism in cancer, serotonergic synapse, Fc epsilon RI signaling pathway, GnRH signaling pathway, and so on related to the above twenty targets were identified. The pharmacology network analysis indicated that the differential components may be helpful in treating various diseases, especially cancer, by exerting antioxidant activity. In conclusion, this study provided a novel method for identifying active components with antioxidant activity in SSF and SCF, and this method may be applicable for the filtration of bioactive components in other herbs.

Release of redox enzymes and micro-RNAs in extracellular vesicles, during infection and inflammation

Many studies reported that redox enzymes, particularly thioredoxin and peroxiredoxin, can be released by cells and act as soluble mediators in immunity. Recently, it became clear that peroxiredoxins can be secreted via the exosome-release route, yet it remains unclear how this exactly happens and why. This review will first introduce briefly the possible redox states of protein cysteines and the role of redox enzymes in their regulation. We will then discuss the studies on the extracellular forms of some of these enzymes, their association with exosomes/extracellular vesicles and with exosome micro-RNAs (miRNAs)/mRNAs involved in oxidative processes, relevant in infection and inflammation.

Acetylshikonin Induces Apoptosis in Human Colorectal Cancer HCT-15 and LoVo Cells via Nuclear Translocation of FOXO3 and ROS Level Elevation

Acetylshikonin, a naphthoquinone, is a pigment compound derived from Arnebia sp., which is known for its anti-inflammatory potential. However, its anticarcinogenic effect has not been well investigated. Thus, in this study, we focused on investigating its apoptotic effects against HCT-15 and LoVo cells, which are human colorectal cancer cells. MTT assay, cell counting assay, and colony formation assay have shown acetylshikonin treatment induced cytotoxic and antiproliferative effects against colorectal cancer cells in a dose- and time-dependent manner. DNA fragmentation was observed via terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay. Also, the increase of subG1 phase in cell cycle arrest assay and early/late apoptotic rates in annexin V/propidium iodide (PI) double staining assay was observed, which indicates an apoptotic potential of acetylshikonin against colorectal cancer cells. 2′,7′-Dichlorofluorescin diacetate (DCF-DA) staining was used to evaluate reactive oxygen species (ROS) generation in acetylshikonin-treated colorectal cancer cells. Fluorescence-activated cell sorting (FACS) analysis showed that acetylshikonin induced an increase in reactive oxygen species (ROS) levels and apoptotic rate in a dose- and time-dependent manner in HCT-15 and LoVo cells. In contrast, cotreatment with N-acetyl cysteine (NAC) has reduced ROS generation and antiproliferative effects in colorectal cancer cells. Western blotting analysis showed that acetylshikonin treatment induced increase of cleaved PARP, γH2AX, FOXO3, Bax, Bim, Bad, p21, p27, and active forms of caspase-3, caspase-7, caspase-9, caspase-6, and caspase-8 protein levels, while those of inactive forms were decreased. Also, the expressions of pAkt, Bcl-2, Bcl-xL, peroxiredoxin, and thioredoxin 1 were decreased. Furthermore, western blotting analysis of cytoplasmic and nuclear fractionated proteins showed that acetylshikonin treatment induced the nuclear translocation of FOXO3, which might result from DNA damage by the increased intracellular ROS level. This study represents apoptotic potential of acetylshikonin against colorectal cancer cells via translocation of FOXO3 to the nucleus and upregulation of ROS generation.

Dimethyl Fumarate, an Approved Multiple Sclerosis Treatment, Reduces Brain Oxidative Stress in SIV-Infected Rhesus Macaques: Potential Therapeutic Repurposing for HIV Neuroprotection

Dimethyl fumarate (DMF), an antioxidant/anti-inflammatory drug approved for the treatment of multiple sclerosis, induces antioxidant enzymes, in part through transcriptional upregulation. We hypothesized that DMF administration to simian immunodeficiency virus (SIV)-infected rhesus macaques would induce antioxidant enzyme expression and reduce oxidative injury and inflammation throughout the brain. Nine SIV-infected, CD8⁺-T-lymphocyte-depleted rhesus macaques were studied. Five received oral DMF prior to the SIV infection and through to the necropsy day. Protein expression was analyzed in 11 brain regions, as well as the thymus, liver, and spleen, using Western blot and immunohistochemistry for antioxidant, inflammatory, and neuronal proteins. Additionally, oxidative stress was determined in brain sections using immunohistochemistry (8-OHdG, 3NT) and optical redox imaging of oxidized flavoproteins containing flavin adenine dinucleotide (Fp) and reduced nicotinamide adenine dinucleotide (NADH). The DMF treatment was associated with no changes in virus replication; higher expressions of the antioxidant enzymes NQO1, GPX1, and HO-1 in the brain and PRDX1 and HO-2 in the spleen; lower levels of 8-OHdG and 3NT; a lower optical redox ratio. The DMF treatment was also associated with increased expressions of cell-adhesion molecules (VCAM-1, ICAM-1) and no changes in HLA-DR, CD68, GFAP, NFL, or synaptic proteins. The concordantly increased brain antioxidant enzyme expressions and reduced oxidative stress in DMF-treated SIV-infected macaques suggest that DMF could limit oxidative stress throughout the brain through effective induction of the endogenous antioxidant response. We propose that DMF could potentially induce neuroprotective brain responses in persons living with HIV.

Molecular profiling and functional delineation of peroxiredoxin 3 (HaPrx3) from the big-belly seahorses (Hippocampus abdominalis) and understanding their immunological responses

Peroxiredoxins (Prxs) are ubiquitously expressed antioxidant proteins that can protect aerobic organisms from oxidative stress. Here, we characterized the HaPrx3 homolog at the molecular level from big-belly seahorse (Hippocampus abdominalis) and analyzed its functional activities. The coding sequence of HaPrx3 consists of 726 bp, which encodes 241 amino acids. The predicted molecular weight and theoretical isoelectric point (pI) of HaPrx3 was 26.20 kDa and 7.04, respectively. Multiple sequence alignments revealed that the arrangements of domains, catalytic triads, dimers, and decamer interfaces of HaPrx3 were conserved among Prx sequences of other organisms. According to the phylogenetic analysis, HaPrx3 is clustered with the teleost Prx3 subclade. The highest transcript level of HaPrx3 was detected in the ovary tissue among fourteen healthy fish tissues. The mRNA levels of HaPrx3 in blood and liver tissues were significantly (P < 0.05) upregulated in response to lipopolysaccharide (LPS), polyinosinic-polycytidylic (poly I:C), Edwardsiella tarda, and Streptococcus iniae, suggesting its involvement in immune responses. Under functional properties, insulin disulfide reduction assay confirmed the oxidoreductase activity of recombinant HaPrx3. A cell viability assay and Hoechst staining indicated cell survival ability and reduction of apoptotic activity, respectively. Moreover, a peroxidase activity assay verified peroxidase activity, while a metal-catalyzed oxidation (MCO) assay indicated the DNA protection ability of HaPrx3. Collectively, it is concluded that HaPrx3 may play a significant role in oxidative stress and immune responses against pathogenic infections in big-belly seahorses.

β-Elemene enhances radiosensitivity in non-small-cell lung cancer by inhibiting epithelial-mesenchymal transition and cancer stem cell traits via Prx-1/NF-kB/iNOS signaling pathway

Radiation therapy is widely used to treat a variety of malignant tumors, including non-small-cell lung cancer (NSCLC). However, ionizing radiation (IR) paradoxically promotes radioresistance, metastasis and recurrence by inducing epithelial-mesenchymal transition (EMT) and cancer stem cells (CSCs). Here, we developed two NSCLC radioresistant (RR) cell lines (A549-RR and H1299-RR) and characterized their motility, cell cycle distribution, DNA damage, and CSC production using migration/invasion assays, flow cytometry, comet assays, and sphere formation, respectively. We also evaluated their tumorigenicity in vivo using a mouse xenograft model. We found that invasion and spheroid formation by A549-RR and H1299-RR cells were increased as compared to their parental cells. Furthermore, as compared to radiation alone, the combination of β-elemene administration with radiation increased the radiosensitivity of A549 cells and reduced expression of EMT/CSC markers while inhibiting the Prx-1/NF-kB /iNOS signaling pathway. Our findings suggest that NSCLC radioresistance is associated with EMT, enhanced CSC phenotypes, and activation of the Prx-1/NF-kB/iNOS signaling pathway. They also suggest that combining β-elemene with radiation may be an effective means of overcoming radioresistance in NSCLC.

Transcriptional modifications and the cytoprotective, DNA protective, and wound healing effects of peroxiredoxin-1 from Sebastes schlegelii

Peroxiredoxins are a group of thiol-specific antioxidant proteins that take six isoforms in vertebrates and allow the innate immune system to sense and detoxify reactive oxygen species. In this study, we identified and characterized the perxiredoxin-1 (SsPrdx1) cDNA sequence from the rockfish, Sebastes schlegelii. In silico analysis revealed that SsPrdx1 contained a 594 bp long open reading frame (ORF) encoding a protein of 198 amino acids, with a predicted molecular weight and theoretical isoelectric point of 21.97 kDa and 6.30, respectively. The SsPrdx1 gene comprised six exons linked by five introns, while peroxiredoxin signature motifs were found in the highly conserved third, fourth, and fifth exons. Phylogenetic analysis and sequence alignment suggested that SsPrdx1 is evolutionarily conserved and that its most closely related counterpart is Salarias fasciatus. Recombinant SsPrdx1 (rSsPrdx1) displayed supercoiled DNA protection and insulin disulfide reduction activities in a concentration-dependent manner, while cells transiently transfected with pcDNA3.1 (+)/SsPrdx1 exhibited significant cytoprotective effects under oxidative stress and wound healing activity. SsPrdx1 transcripts were constitutively expressed under normal physiological conditions, with the highest expression observed in the blood. Moreover, SsPrdx1 expression increased in the blood, spleen, and liver following immune provocation by LPS, poly I:C, and Streptococcus iniae injection. Thus, this study provides insights into the role of SsPrdx1 in rockfish immune protection.

Induction of apoptosis in indole-3-carbinol-treated lung cancer H1299 cells via ROS level elevation

This study was focused on investigating the anticancer potential of indole-3-carbinol (I3C) against lung cancer H1299 cells via an increase in ROS levels. To investigate the induction of growth arrest and/or cell death in H1299 cells, a cell cycle arrest assay, terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick-end labeling (TUNEL) assay, and reactive oxygen species (ROS) detection assay were performed. Through the TUNEL assay, we detected I3C-induced DNA fragmentation. Fluorescence-activated cell sorting (FACS) analysis showed that I3C induced an increase in ROS levels and apoptotic rate in a dose- and time-dependent manner in H1299 cells. Western blotting demonstrated that activated forms of caspase-3, caspase-7, caspase-9, and poly (ADP-ribose) polymerase (PARP) were increased in I3C-treated H1299 cells following treatment with I3C. Furthermore, protein expression levels of FOXO3, bim, bax, and phosphorylated ERK and JNK were increased, while those of pAkt, Bcl-xL, and Bcl-2 were decreased by I3C treatment of H1299 cells. To confirm the relationship between cell apoptosis and ROS generation, H1299 cells were treated with I3C simultaneously with N-acetylcysteine (NAC), and it was shown that ROS levels decreased and viability increased. Moreover, in western blot analysis, expression of anti-apoptotic proteins (thioredoxin1, peroxiredoxin-1, Bcl-2, and Bcl-xL) in I3C-treated cells was evidently downregulated and pro-apoptotic proteins (active ASK1 and cleaved PARP) were upregulated compared to cells co-treated with NAC. The study showed that I3C induced downregulation of ROS regulator proteins and elevation of ROS, thus activating apoptotic signaling cascades in human lung cancer H1299 cells.

CD1d1 intrinsic signaling in macrophages controls NLRP3 inflammasome expression during inflammation

Dysregulation of immune responses in the gut often associates with inflammatory bowel diseases (IBD). Mouse CD1d1, an ortholog of human CD1d mainly participating in lipid-antigen presentation to NKT cells, is able to generate intrinsic signals upon stimulation. Mice with macrophage-specific CD1d1 deficiency (Lym^CD1d1-/- ) acquire resistance to dextran sodium sulfate (DSS)-induced colitis, attributing to the transcriptional inhibition of NLRP3 inflammasome components. The hyperactivation of NLRP3 inflammasome accounts for gut epithelial proliferation and intestine-blood barrier integrity. Mechanistically, occupancy by the natural ligand glycosphingolipid iGb3, CD1d1 responds with intracellular Ser³³⁰ dephosphorylation thus to reduce the Peroxiredoxin 1 (PRDX1)-associated AKT-STAT1 phosphorylation and subsequent NF-κB activation, eventually causing transcriptional down-regulation of Nlrp3 and its immediate substrates Il1b and Il18 in macrophages. Therefore, the counterbalancing role of CD1d1 in macrophages appears to determine severity of DSS-mediated colitis in mice. These findings propose new intervention strategies for treating IBD and other inflammatory disorders.

Large yellow croaker peroxiredoxin IV protect cells against oxidative damage and apoptosis

Oxidative stress and inflammation lead to cell damage and are implicated in many disease states. High concentrations of hydrogen peroxide (H₂O₂) may mediate cells apoptosis by increasing intracellular reactive oxygen species (ROS) levels. In this study, we established a LYCK-PrxIV cell line (large yellow croaker head kidney cell line stably expressing peroxiredoxin IV). The level of nitric oxide (NO), superoxide anion and hydrogen peroxide (H₂O₂) in this LYCK-PrxIV cells were significantly lower than those in control cells of LYCK-pcDNA3.1 (LYCK cell line stably transfected by pcDNA3.1 vector). Additionally, when exposed to H₂O₂, cell apoptosis was significantly alleviated in LYCK-PrxIV than in control cells. Meanwhile, the ROS level and ATP content were maintained more stable in LYCK-PrxIV than in LYCK-pcDNA3.1. The over-expression of LcPrxIV in LYCK-PrxIV cells induced a declined mRNA expression of LcCXC, LcCC, LcIL-8 and LcTNF-α2, as well as an increase of LcIL-10 mRNA expression, when compared to LYCK-pcDNA3.1. On the other hand, the expression of chemokine LcCXC, LcCC and LcTNF-a2 increased in LYCK-pcDNA3.1 after H₂O₂ stimulation, while that of LcIL-8 and LcIL-10 decreased. The regualtion of gene expression in LYCK-PrxIV cells was almost the same as that in LYCK-pcDNA3.1, but the change fold was much more moderate. These results suggest that LcPrxIV may be an indispensable ROS scavenger protecting LYCK cells against oxidative damage as well as the subsequent apoptosis and inflammatory response, which provides a clue that LcPrxIV may be an assist in fish immune response.

Combined signaling of NF-kappaB and IL-17 contributes to Mesenchymal stem cells-mediated protection for Paraquat-induced acute lung injury

BACKGROUND

Paraquat (PQ) is an herbicide widely used in the world. PQ can cause pulmonary toxicity and even acute lung injury. Treatment for PQ poisoning in a timely manner is still a challenge for clinicians. Mesenchymal stem cell (MSC) transplantation has hold potentials for the treatment of several lung diseases including PQ poisoning. The aim of this study is to examine the mechanisms mediated by MSC transplantation to protect PQ-induced lung injury.

METHODS

Here we performed the whole genome sequencing and compared the genes and pathways in the lung that were altered by PQ or PQ together with MSC treatment.

RESULTS

The comparison in transcriptome identified a combined mitigation in NF-kappaB signaling and IL-17 signaling in MSC transplanted samples.

CONCLUSION

This study not only reiterates the important role of NF-kappaB signaling and IL-17 signaling in the pathogenesis of PQ-induced toxicity, but also provides insight into a molecular basis of MSC administration for the treatment of PQ-induced toxicity.

Peroxiredoxin-1 aggravates lipopolysaccharide-induced septic shock via promoting inflammation

Septic shock induced by lipopolysaccharide (LPS) is characterized by serious systemic inflammatory response and robust production of pro-inflammatory cytokines from activated macrophages. Damage-associated molecular patterns (DAMPs) secreted by activated macrophages are key contributors to septic shock. However, the current knowledge on those DAMPs that promote inflammatory response under LPS-induced septic shock remains poorly understood. Here, we report that Peroxiredoxin 1 (Prdx1) plays a detrimental role in LPS-induced septic shock. Intraperitoneal injection of LPS elicited a progressive course of septic shock in mice, which was characterized by significant lethality along with robust production of cytokines (IL-1β, IL-6 and TNF-α). Removal of Prdx1 strongly protected mice from LPS-induced death, and decreased IL-1β, IL-6 and TNF-α productions. Additionally, primary macrophages deficient in Prdx1 are less able to produce much more IL-1β, IL-6 and TNF-α. Collectively, we provide a demonstration for Prdx1 contributing to LPS-induced septic shock likely via promoting inflammation.

The role of microglia in neuroprogressive disorders: mechanisms and possible neurotherapeutic effects of induced ketosis

A comprehensive review of molecular mechanisms involved in the promotion and maintenance of distinct microglia phenotypes is provided. The acquisition and perpetuation of predominantly pro-inflammatory microglial phenotypes have been implicated in the pathophysiology of several neuroprogressive diseases and is associated with reduced ATP production via oxidative phosphorylation, increased ATP generation by glycolysis, elevated oxidative and nitrosative stress and other metabolic, inflammatory and hormonal insults. Microglia can also adopt a predominantly anti-inflammatory phenotypes with neuroprotective properties. Strategies that promote and maintain a predominantly anti-inflammatory phenotype may hold promise as novel therapeutic opportunities for neuroprogressive illness. Induced ketosis may promote a transition towards predominantly anti-inflammatory microglial states/phenotypes by several mechanisms, including inhibition of glycolysis and increased NAD⁺ production; engagement of microglial GPR109A receptors; histone deacetylase inhibition; and elevated n-3 polyunsaturated fatty acids levels. Since microglia activation can now be assessed in vivo, these data provide a clear rationale for the design of transdiagnostic randomized controlled trials of the ketogenic diet and other ketosis-inducing strategies for neuroprogressive diseases, which may also provide mechanistic insights through the assessment of "target engagement".

Molecular mechanisms of selenium-biofortified soybean protein and polyphenol conjugates in protecting mouse skin damaged by UV-B

Selenium-biofortified crops are a quality functional food resource because of their anti-tumor and anti-cancer properties. In the present study, the conjugates of selenium-biofortified soybean protein and polyphenols were prepared and evaluated by alkali-induced synthesis and in vitro antioxidant tests. Moreover, the antioxidant mechanisms of protecting mice skin damaged by UV-B were studied. The results showed that the antioxidant activity of the conjugate between 7S globulin from selenium-enriched soybean (Se-7S) and EGCG (Se-7S-EGCG) was significantly higher (P < 0.05) than that of Se-7S-GA. Structural characterizations implied that the polymerization of polyphenols with amino acid residues occurred. Se-7S-EGCG inhibited the apoptosis of epidermal cells induced by UV-B. The overexpression of phosphorylated proteins in the MAPK signaling pathway, the activation of related inflammatory factors, and the boost in the MMPs were reversed by Se-7S-EGCG. Overall, this research provides a theoretical and experimental basis for the application of protein and polyphenol conjugates in food and medicine fields.

Knockout Mouse Models for Peroxiredoxins

Peroxiredoxins (PRDXs) are members of a highly conserved peroxidase family and maintain intracellular reactive oxygen species (ROS) homeostasis. The family members are expressed in most organisms and involved in various biological processes, such as cellular protection against ROS, inflammation, carcinogenesis, atherosclerosis, heart diseases, and metabolism. In mammals, six PRDX members have been identified and are subdivided into three subfamilies: typical 2-Cys (PRDX1, PRDX2, PRDX3, and PRDX4), atypical 2-Cys (PRDX5), and 1-Cys (PRDX6) subfamilies. Knockout mouse models of PRDXs have been developed to investigate their in vivo roles. This review presents an overview of the knockout mouse models of PRDXs with emphases on the biological and physiological changes of these model mice.

Mesenchymal stem cell-derived exosomes ameliorate intervertebral disc degeneration via anti-oxidant and anti-inflammatory effects

Excessive oxidative stress and inflammation are the key early events in the development of intervertebral disc degeneration (IVDD). The NACHT, LRR, and PYD domain-containing protein 3 (NLRP3) inflammasome has been identified as the major source of oxidative stress and the inflammatory responses and thus is an attractive therapeutic target for IVDD. However, currently, there are no reports on the use of mesenchymal stem cell (MSC)-derived exosomes to reduce NLRP3 inflammasome expression for IVDD treatment. The present study aimed to investigate the therapeutic effect of exosomes for use as IVDD therapeutics. We first manufactured and evaluated the characteristics of exosomes. Then, we investigated the effects of exosomes on H₂O₂-induced nucleus pulposus (NP) cell inflammation. Third, we tested the function of exosomes with respect to H₂O₂-induced ROS production and mitochondrial dysfunction. Finally, the therapeutic effect of exosomes on IVDD was investigated using a rabbit IVDD model. Results showed that exosomes play an anti-inflammatory role in pathological NP cells by suppressing inflammatory mediators and NLRP3 inflammasome activation. Moreover, it was suggested that exosomes might supply mitochondrial proteins to NP cells, and that the damaged mitochondria could be restored with this supplement. Further, in the rabbit IVDD model, exosomes significantly prevented the progression of degenerative changes. Our results confirmed that the NLRP3 inflammasome is an effective target for IVDD treatment and that the injection of exosomes could be a promising therapeutic strategy.

Long Noncoding RNA Expression Profile in BV2 Microglial Cells Exposed to Lipopolysaccharide

Neuropathic pain, which is one of the most common forms of chronic pain, seriously increases healthcare costs and impairs patients' quality of life with an incidence of 7–10% worldwide. Microglia cell activation plays a key role in the progression of neuropathic pain. Better understanding of novel molecules modulating microglia cell activation and these underlying functions will extremely benefit the exploration of new treatment. Recent studies suggested long noncoding RNAs may be involved in neuropathic pain. However, its underlying functions and mechanisms in microglia cell activation remain unclear. To identify the differentially expressed lncRNAs and predict their functions in the progression of microglia cell activation, GSE103156 was analyzed using integrated bioinformatics methods. The expression levels of selected lncRNAs and mRNAs were determined by real-time PCR. In the present study, a total of 56 lncRNAs and 298 mRNAs were significantly differentially expressed. The differentially expressed mRNAs were mainly enriched in NF-kappa B signaling pathway, TNF signaling pathway, Toll-like receptor signaling pathway, and NOD-like receptor signaling pathway. The top 10 hub genes were Tnf, Il6, Stat1, Cxcl10, Il1b, Tlr2, Irf1, Ccl2, Irf7, and Ccl5 in the PPI network. Our results showed that Gm8989, Gm8979, and AV051173 may be involved in the progression of microglia cell activation. Taken together, our findings suggest that lots of lncRNAs may be involved in BV2 microglia cell activation in vitro. The findings may provide relevant information for the development of promising targets for the microglial cells activation of neuropathic pain in vivo in the future.

Circulating Peroxiredoxin-1 is a novel damage-associated molecular pattern and aggravates acute liver injury via promoting inflammation

Sterile inflammation is initiated by damage-associated molecular patterns (DAMPs) and a key contributor to acute liver injury (ALI). However, the current knowledge on those DAMPs that activate hepatic inflammation under ALI remains incomplete. We report here that circulating peroxiredoxin-1 (Prdx1) is a novel DAMP for ALI. Intraperitoneal injection of acetaminophen (APAP) elicited a progressive course of ALI in mice, which was developed from 12 to 24 h post injection along with liver inflammation evident by macrophage infiltration and upregulations of cytokines (IL-1β, IL-6 and TNF-α); these alterations were concurrently occurred with a robust and progressive production of serum Prdx1. Similar observations were also obtained in carbon tetrachloride (CCl₄)-induced ALI in mice. Removal of the source of serum Prdx1 protected mice deficient in Prdx1 from APAP and CCl₄-induced liver injury, and decreased macrophage infiltration, IL-1β, IL-6 and TNF-α production. As a result, Prdx1^-/- mice were strongly protected from APAP-induced death that was likely progressed from ALI. Additionally, intravenous re-introduction of recombinant Prdx1 (rPrdx1) in Prdx1^-/- mice reversed or reduced all the above events, demonstrating an important contribution of circulating Prdx1 to ALI. rPrdx1 potently induced in primary macrophages the expression of pro-IL-1β, IL-6, TNF-α, and IL-1β through the NF-κB signaling as well as the NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome signaling, evident by caspase-1 activation. Furthermore, a significant elevation of serum Prdx1 was demonstrated in patients (n = 15) with ALI; the elevation is associated with ALI severity. Collectively, we provide the first demonstration for serum Prdx1 contributing to ALI.

Fluoride activates microglia, secretes inflammatory factors and influences synaptic neuron plasticity in the hippocampus of rats

Epidemiological studies have reported that highly fluoridated drinking water may significantly decrease the Intelligence Quotient (IQ) of exposed children. It is thought that synaptic plasticity is the basis of learning and memory skills in developing children. However, the effect on synaptic plasticity by activated microglia induced via fluoride treatment is less clear. Our previous research showed that fluoride ions activated microglia which then released pro-inflammatory cytokines. In this study, hippocampal-dependent memory status was evaluated in rat models sub-chronically exposed to fluoride in their drinking water. Microglial activation in the hippocampus was examined using immunofluorescence staining and the expression of synaptophysin (SYP) and postsynaptic density protein 95 (PSD-95), Long-term potentiation (LTP) and the expression of Amino-3-hydroxy-5-methy-4-isoxazole propionate (AMPA) receptor subunit GluR2 as well as N-methyl-d-aspartate (NMDA) receptor subunit NMDAR2β of exposed rats. We found that fluoride exposure activated microglia and increased the expression of DAP12 and TREM2, as well as promoted pro-inflammatory cytokines secretion via ERK/MAPK and P38/MAPK signal pathways. Furthermore fluoride depressed LTP and decreased PSD-95 protein levels as well as expression of ionotropic glutamate receptors GluR2 and NMDAR2β. We concluded that the role of fluoride on synaptic plasticity may be associated with neuroinflammation induced by microglia.

Novel hyperoxidation resistance motifs in 2-Cys peroxiredoxins

2-Cys peroxiredoxins (Prxs) modulate hydrogen peroxide (H₂O₂)-mediated cell signaling. At high H₂O₂ levels, eukaryotic Prxs can be inactivated by hyperoxidation and are classified as sensitive Prxs. In contrast, prokaryotic Prxs are categorized as being resistant to hyperoxidation and lack the GGLG and C-terminal YF motifs present in the sensitive Prxs. Additional molecular determinants that account for the subtle differences in the susceptibility to hyperoxidation remain to be identified. A comparison of a new, 2.15-Å-resolution crystal structure of Prx2 in the oxidized, disulfide-bonded state with the hyperoxidized structure of Prx2 and Prx1 in complex with sulfiredoxin revealed three structural regions that rearrange during catalysis. With these regions in hand, focused sequence analyses were performed comparing sensitive and resistant Prx groups. From this combinatorial approach, we discovered two novel hyperoxidation resistance motifs, motifs A and B, which were validated using mutagenesis of sensitive human Prxs and resistant Salmonella enterica serovar Typhimurium AhpC. Introduction and removal of these motifs, respectively, resulted in drastic changes in the sensitivity to hyperoxidation with Prx1 becoming 100-fold more resistant to hyperoxidation and AhpC becoming 800-fold more sensitive to hyperoxidation. The increased sensitivity of the latter AhpC variant was also confirmed in vivo These results support the function of motifs A and B as primary drivers for tuning the sensitivity of Prxs to different levels of H₂O₂, thus enabling the initiation of variable signaling or antioxidant responses in cells.

Age-dependent regulation of antioxidant genes by p38α MAPK in the liver

p38α is a redox sensitive MAPK activated by pro-inflammatory cytokines and environmental, genotoxic and endoplasmic reticulum stresses. The aim of this work was to assess whether p38α controls the antioxidant defense in the liver, and if so, to elucidate the mechanism(s) involved and the age-related changes. For this purpose, we used liver-specific p38α-deficient mice at two different ages: young-mice (4 months-old) and old-mice (24 months-old). The liver of young p38α knock-out mice exhibited a decrease in GSH levels and an increase in GSSG/GSH ratio and malondialdehyde levels. However, old mice deficient in p38α had higher hepatic GSH levels and lower GSSG/GSH ratio than young p38α knock-out mice. Liver-specific p38α deficiency triggered a dramatic down-regulation of the mRNAs of the key antioxidant enzymes glutamate cysteine ligase, superoxide dismutase 1, superoxide dismutase 2, and catalase in young mice, which seems mediated by the lack of p65 recruitment to their promoters. Nrf-2 nuclear levels did not change significantly in the liver of young mice upon p38α deficiency, but nuclear levels of phospho-p65 and PGC-1α decreased in these mice. p38α-dependent activation of NF-κB seems to occur through classical IκB Kinase and via ribosomal S6 kinase1 and AKT in young mice. However, unexpectedly the long-term deficiency in p38α triggers a compensatory up-regulation of antioxidant enzymes via NF-κB activation and recruitment of p65 to their promoters. In conclusion, p38α MAPK maintains the expression of antioxidant genes in liver of young animals via NF-κΒ under basal conditions, whereas its long-term deficiency triggers compensatory up-regulation of antioxidant enzymes through NF-κΒ.

Danger signals in stroke and their role on microglia activation after ischemia

Ischemic stroke is a major cause of death. Besides the direct damage resulting from oxygen and glucose deprivation, sterile inflammation plays a pivotal role in increasing cellular death. Damaged-associated molecular patterns (DAMPs) are passively released from dying cells and activate the innate immune system. Thus, they take part in the direct and rapid activation of the inflammatory response after stroke onset. In this review the role of the most important DAMPs, high mobility group box 1, heat and cold shock proteins, purines, and peroxiredoxins, are addressed. Moreover, intracellular pathways activated by DAMPs in microglia are illuminated.

Antioxidative properties and structural features of atypical 2-Cys peroxiredoxin from Sebastes schlegelii

Atypical 2-Cys peroxiredoxin (Prx5) is an antioxidant protein that exerts its antioxidant function by detoxifying different reactive oxygen species (ROS). Here, we identified mitochondrial Prx5 from rockfish (SsPrx5) and described its specific structural and functional characteristics. The open reading frame (ORF) of SsPrx5 (570 bp) was translated into a 190-amino acid polypeptide that contained a mitochondrial targeting sequence (MTS), thioredoxin 2 domain, two Prx-specific signature motifs, and three conserved cysteine residues. Sequence comparison indicated that the SsPrx5 protein sequence shared greatest identity with teleost orthologs, where the phylogenetic results showed an evolutionary position within the fish Prx5. The coding sequence of SsPrx5 was scattered in six exons as found in other vertebrates. Additionally, the potent antioxidant functions of recombinantly expressed SsPrx5 protein was demonstrated by insulin reduction and extracellular H₂O₂ scavenging both in vitro and in vivo. Quantitative real time PCR (qPCR) detected ubiquitous mRNA expression of SsPrx5 in healthy rockfish tissues, with remarkable expression observed in gill, liver, and reproductive tissues. Prompt transcription of SsPrx5 was shown in the immune-stimulated gill and liver tissues against Streptococcus iniae and lipopolysaccharide injection. Taken together, present results suggest the indispensable role of SsPrx5 in the rockfish antioxidant defense system against oxidative stresses and its role in maintaining redox balance upon pathogen invasion.

Immunosuppressive effects and associated compensatory responses in zebrafish after full life-cycle exposure to environmentally relevant concentrations of cadmium

In natural environments, fish survive in polluted water by cadmium (Cd) throughout their whole life cycle. However, little information is available on Cd toxicity considering a life cycle assessment. The present study investigated effects of environmental levels of cadmium (0, 2.5, and 5μg/L) on immune responses in liver and spleen of zebrafish for 15 weeks, from embryos to sexually maturity. Nitric oxide (NO) levels and iNOS activity declined in liver and spleen of zebrafish exposed to 5μg/L Cd, suggesting an immunosuppressive effect. The result was further supported by the decreased transcriptional levels of proinflammatory cytokines by Cd, such as interleukin-6 (IL-6), interleukin-10 (IL-10), interleukin-1β (IL-1β), and tumour necrosis factor-α (TNF-α) in liver. However, a sharp increase in the mRNA levels of these cytokines was observed in spleen of zebrafish exposed to Cd. The increased mRNA expression of these proinflammatory cytokines may be the secondary effect following immunosuppression and just reflect a compensatory mechanism for coping with the decreased immunity, which may explain an increase in mRNA levels and a decrease in iNOS activity in spleen of zebrafish exposed to Cd. In liver, the down-regulated mRNA levels of iNOS paralleled with the decreased iNOS activity, suggesting a synchronous response from a molecular level to a biochemical level. Positive correlations between mRNA expression levels of nuclear transcription factor κB (NF-κB) and proinflammatory cytokines were also observed, suggesting that NF-κB might be required for the protracted induction of inflammatory genes. The corresponding changes in the mRNA levels of the inhibitor of κBα (IκBαa and IκBαb) may form a feedback loop to restore transcriptional activity of NF-κB. Furthermore, splenic ROS levels were increased by 5μg/L Cd, possibly activating NF-κB pathway. Taken together, immunosuppressive effects and tissue-dependent compensatory responses were demonstrated in zebrafish after full life-cycle exposure to environmental levels of Cd, indicating a compromise between survival and immunity.

Microglia antioxidant systems and redox signalling

For many years, microglia, the resident CNS macrophages, have been considered only in the context of pathology, but microglia are also glial cells with important physiological functions. Microglia-derived oxidant production by NADPH oxidase (NOX2) is implicated in many CNS disorders. Oxidants do not stand alone, however, and are not always pernicious. We discuss in general terms, and where available in microglia, GSH synthesis and relation to cystine import and glutamate export, and the thioredoxin system as the most important antioxidative defence mechanism, and further, we discuss in the context of protein thiolation of target redox proteins the necessity for tightly localized, timed and confined oxidant production to work in concert with antioxidant proteins to promote redox signalling. NOX2-mediated redox signalling modulates the acquisition of the classical or alternative microglia activation phenotypes by regulating major transcriptional programs mediated through NF-κB and Nrf2, major regulators of the inflammatory and antioxidant response respectively. As both antioxidants and NOX-derived oxidants are co-secreted, in some instances redox signalling may extend to neighboring cells through modification of surface or cytosolic target proteins. We consider a role for microglia NOX-derived oxidants in paracrine modification of synaptic function through long term depression and in the communication with the adaptive immune system. There is little doubt that a continued foray into the functions of the antioxidant response in microglia will reveal antioxidant proteins as dynamic players in redox signalling, which in concert with NOX-derived oxidants fulfil important roles in the autocrine or paracrine regulation of essential enzymes or transcriptional programs.

LINKED ARTICLES

This article is part of a themed section on Redox Biology and Oxidative Stress in Health and Disease. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.12/issuetoc.

The 1-Tosylpentan-3-one Protects against 6-Hydroxydopamine-Induced Neurotoxicity

Previous studies have demonstrated that the marine compound austrasulfone, isolated from the soft coral Cladiella australis, exerts a neuroprotective effect. The intermediate product in the synthesis of austrasulfone, dihydroaustrasulfone alcohol, attenuates several inflammatory responses. The present study uses in vitro and in vivo methods to investigate the neuroprotective effect of dihydroaustrasulfone alcohol-modified 1-tosylpentan-3-one (1T3O). Results from in vitro experiments show that 1T3O effectively inhibits 6-hydroxydopamine-induced (6-OHDA-induced) activation of both p38 mitogen-activated protein kinase (MAPK) and caspase-3 in SH-SY5Y cells; and enhances nuclear factor erythroid 2–related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) expression via phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt) signaling. Hoechst staining and Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining results reveal that 1T3O significantly inhibits 6-OHDA-induced apoptosis. In addition, the addition of an Akt or HO-1 inhibitor decreases the protective effect of 1T3O. Thus, we hypothesize that the anti-apoptotic activity of 1T3O in neuronal cells is mediated through the regulation of the Akt and HO-1 signaling pathways. In vivo experiments show that 1T3O can reverse 6-OHDA-induced reduction in locomotor behavior ability in zebrafish larvae, and inhibit 6-OHDA-induced tumor necrosis factor-alpha (TNF-α) increase at the same time. According to our in vitro and in vivo results, we consider that 1T3O exerts its anti-apoptotic activities at SH-SY5Y cells after 6-OHDA challenges, probably via the regulation of anti-oxidative signaling pathways. Therefore, this compound may be a promising therapeutic agent for neurodegenerations.

Differences in Proinflammatory Property of Six Subtypes of Peroxiredoxins and Anti-Inflammatory Effect of Ligustilide in Macrophages

BACKGROUND

Peroxiredoxins (Prxs) are proposed to function as damage-associated molecular patterns (DAMPs) and contribute to post-ischemic neuroinflammation and brain injury by activating Toll-like receptor (TLR) 4 at the acute and subacute phases after ischemic stroke. However, there are few studies concerning the inflammatory profiles of six distinct subtypes of Prxs (Prx1-Prx6). Our previous study demonstrated that the protective effect of ligustilide (LIG) against cerebral ischemia was associated with inhibition of neuroinflammatory response and Prx/TLR4 signaling in rats. Herein, the present study explored the inflammatory members of Prxs and the effect of LIG on their inflammatory responses in macrophages.

METHODOLOGY/PRINCIPAL FINDINGS

The murine RAW264.7 macrophages were treated with each of exogenous recombinant Prxs at a range of 1 to 50 nM for 24 h. The WST-1 test showed that Prx3 exhibited a significant cytotoxicity, whereas the rest five Prxs did not affect cellular viability. The quantitative measurements with spectrometry or ELISA indicated that three subtypes, Prx1, Prx2 and Prx4, increased production of proinflammatory mediators, including nitric oxide (NO) metabolites, tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) in a concentration-dependent manner. Immunostaining demonstrated that 20 nM Prx1, Prx2 or Prx4 significantly increased expression of TLR4 and iNOS and nuclear translocation of NF-κB p65. However, Prx5 and Prx6 showed no poinflammatory effect in macrophages. Remarkably, LIG treatment effectively inhibited the inflammatory response induced by Prx1, Prx2 and Prx4.

CONCLUSION

Three members of Prxs, Prx1, Prx2 and Prx4, are inflammatory DAMPs that induce TLR4 activation and inflammatory response in macrophages, which is effectively inhibited by LIG. These results suggest that inflammatory Prxs-activated macrophages may provide a novel cellular model for screening the potential inhibitors of DAMPs-associated inflammatory diseases such as stroke. Moreover, selective blocking strategies targeting the inflammatory subtypes of Prxs probably provide promising therapeutic approaches with a prolonged time window for stroke.