Peroxiredoxin 1 stimulates secretion of proinflammatory cytokines by binding to TLR4

Assessing the Adjuvant Potential of Chinese Hamster Ovary Host Cell Proteins Using an In Vitro Dendritic Cell Assay

Host cell proteins (HCPs) are process-related impurities of therapeutic protein production and may affect product quality or patient safety. In clinical trials, certain HCPs (e.g., PLBL2 or CCL2) that co-purify with the therapeutic protein have been associated with immune reactions in patients. In this study, we examined the adjuvant potential of six commonly detected HCPs from CHO cells (PRDX1, S100A4, PLBL2, CCL2, CLU, and YWHAE) using an in vitro dendritic cell (DC) maturation assay. Recombinant HCPs were expressed in CHO cells to mimic manufacturing conditions. PRDX1, S100A4, and PLBL2 caused a slight increase in the expression of maturation markers on DCs, while YWHAE, CLU, and CCL2 did not. Interestingly, CLU and CCL2 reduced the DC maturation induced by rituximab. In addition, we observed that process parameters such as elution conditions during chromatographic purification can influence HCP aggregation, which in turn can mask or enhance the intrinsic adjuvant potential of an HCP. These findings not only provide initial insights into the adjuvant potential of individual HCPs but also indicate that the quantity as well as the degree of aggregation of HCPs might influence adjuvanticity.

Serum Amyloid A1 Mediates Paclitaxel Resistance via MD2-Dependent Pathways in Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is difficult to treat due to the lack of clear therapeutic targets. Paclitaxel (PTX) is commonly used to treat TNBC, but drug resistance limits its effectiveness. Myeloid differentiation protein 2 (MD2) and serum amyloid A1 (SAA1) are involved in various diseases, including infections, inflammatory diseases, and cancer. We investigated their role in PTX resistance to identify potential anti-TNBC drugs. In this study, we investigated the changes of SAA1 in TNBC tissues and its role in PTX-induced TNBC cells. Our study revealed SAA1 expressed in the human TNBC subtype and TNBC cells. PTX and CIS induce SAA1 in TNBC cells, and PTX induces inflammatory response via SAA1 in TNBC cells. MD2 blockade increased the sensitivity of TNBC cells to PTX, which was related to the expression of SAA1 during PTX-caused damage of TNBC cells. In further research, SAA1 binds to MD2, promotes the combination of TLR4/MD2 and TLR4/MyD88, activates the NF-κB signaling pathway, and creates the inflammatory microenvironment for cancer cells. Our study reports for the first time that the PTX/SAA1/MD2 axis exists in the PTX-resistance process, which could be a potential treatment target of PTX-resistance.

Unraveling the multifaceted roles of peroxiredoxins in sickle cell anemia: implications in redox and inflammation adaptations

Sickle cell anemia (SCA) presents a complex interplay of factors, with the production of high levels of reactive oxygen species (ROS) and the chronic inflammatory process leading to chronic oxidative stress. In this context, efficient action of antioxidant systems becomes crucial, with particular emphasis on peroxiredoxins (PRDXs) due to their abundance and vital roles. Our primary objective was to establish associations between gene and protein expression of PRDXs 1, 2, and 6, as well as their reducers TRX1, TRXR1, and SRX1, with the characteristic hyperoxidative status observed in SCA patients. Concomitantly, we assessed the production of other essential antioxidant enzymes (SOD1, CAT, and GPX1) in reticulocytes and erythrocytes and explored mRNA levels of the NRF2/KEAP1/PKCδ complex. Our comprehensive analysis revealed a ∼ 3-fold elevation in ROS levels in erythrocytes of patients compared to healthy individuals. However, the NRF2/KEAP1/PKCδ complex exhibited a significant reduction in gene expression, hinting that another transcription factor may regulate the antioxidant response among SCA patients. In addition, the pattern of increased transcript levels of antioxidants in SCA patients was not associated with their protein levels, indicating a possible degradation by proteasome. The protein content of PRDX2 showed a significant reduction, indicating an increased vulnerability of these cells to oxidative damage. Intriguingly, both PRDXs 1 and 2 exhibited significant increases in the plasma of SCA patients, indicating that, besides their well-known intracellular antioxidant role, these enzymes may also play a vital extracellular role in modulating inflammation in these individuals. Our findings unveil novel insights into the redox metabolism adaption of erythroid cells in response to the presence of HbS in homozygosity, thus, into the complex SCA pathophysiology. Moreover, our study reveals the simultaneous presence of both PRDXs 1 and 2 in the plasma of these patients, thereby offering valuable implications for potential prognostic and therapeutic avenues.

Peroxiredoxin 1 Promotes Proinflammatory Cytokine Secretion in Human Dysplastic Oral Keratinocytes and Mouse Tongue Precancerous Tissues

Oxidative stress, a widespread phenomenon involved in many pathological conditions, may be closely related with the progression of oral leukoplakia (OLK). Under chronic inflammation, oxidative stress could stimulate the local formation of a tumor-specific microenvironment in some types of cancer, though not well defined in oral cancer even in OLK. Peroxiredoxin 1 (Prx1), a widely expressed sulfhydryl antioxidant protein, is overexpressed in various tumors and affects tumorigenesis, cell proliferation, apoptosis, invasion, and metastasis. Prx1 also acts as a potent proinflammatory factor. Nuclear factor (NF)-κB is a member of the core dimeric transcription factor family that coordinates the inflammatory response. To investigate the role of Prx1 in oxidative stress-related inflammation in OLK, a coculture model of human dysplastic oral keratinocyte (DOK) and human epidermal fibroblast (HFF) was established and stimulated with H2O2. Cellular reactive oxygen species (ROS) and Prx1 levels in DOK were determined via flow cytometry and western blotting, respectively. Additionally, the levels of the inflammatory factors, interleukin (IL)-6, IL-8, IL-10, and interferon (IFN)-γ, in the conditioned medium were determined via enzyme-linked immunosorbent assay (ELISA). DOK nuclear expression of NF-κB was detected via immunofluorescence assay and western blotting. Moreover, the expression levels of inflammatory factors and the nuclear expression of NF-κB were examined in 4-nitroquinoline-1-oxide (4NQO)-induced tongue precancerous tissues of mice. H2O2 increased Prx1 levels and nuclear expression levels of NF-κB in DOKs and mouse tongue precancerous tissues and elevated the levels of IL-6, IL-8, IL-10, and IFN-γ secreted in the culture supernatants and mouse tongue tissues. However, Prx1 knockdown in DOK and mouse tongue tissues attenuated the upregulation of inflammatory factor and nuclear NF-κB expression levels. Overall, our results suggest that oxidative stress increases Prx1 expression, which promotes inflammatory factor expression by activating NF-κB in human DOK and mouse tongue precancerous tissues.

Peroxiredoxin 1-Toll-like receptor 4-p65 axis inhibits receptor activator of nuclear factor kappa-B ligand-mediated osteoclast differentiation

Peroxiredoxin 1 (PRDX1), an intracellular antioxidant enzyme, has emerged as a regulator of inflammatory responses via Toll-like receptor 4 (TLR4) signaling. Despite this, the mechanistic details of the PRDX1-TLR4 axis and its impact on osteoclast differentiation remain elusive. Here, we show that PRDX1 suppresses RANKL-induced osteoclast differentiation. Utilizing pharmacological inhibitors, we reveal that PRDX1 inhibits osteoclastogenesis through both TLR4/TRIF and TLR4/MyD88 pathways. Transcriptome analysis revealed PRDX1-mediated alterations in gene expression, particularly upregulating serum amyloid A3 (Saa3) and aconitate decarboxylase 1 (Acod1). Mechanistically, PRDX1-TLR4 signaling activates p65, promoting Saa3 and Acod1 expression while inhibiting Nfatc1, a master regulator of osteoclastogenesis. Remarkably, PRDX1 redirects p65 binding from Nfatc1 to Saa3 and Acod1 promoters, thereby suppressing osteoclast formation. Structural analysis showed that a monomeric PRDX1 mutant with enhanced TLR4 binding exhibited the potent inhibition of osteoclast differentiation. These findings reveal the PRDX1-TLR4 axis's role in inhibiting osteoclastogenesis, offering potential therapeutic insights for bone disorders.

Z-Ligustilide: A Potential Therapeutic Agent for Atherosclerosis Complicating Cerebrovascular Disease

Atherosclerosis (AS) is one of the major catalysts of ischemic cerebrovascular disease, and the death and disease burden from AS and its cerebrovascular complications are increasing. Z-ligustilide (Z-LIG) is a key active ingredient in Angelica sinensis (Oliv.) Diels and Ligusticum chuanxiong Hort. In this paper, we first introduced LIG's physicochemical properties and pharmacokinetics. Then, we reviewed Z-LIG's intervention and therapeutic mechanisms on AS and its cerebrovascular complications. The mechanisms of Z-LIG intervention in AS include improving lipid metabolism, antioxidant and anti-inflammatory effects, protecting vascular endothelium, and inhibiting vascular endothelial fibrosis, pathological thickening, and plaque calcification. In ischemic cerebrovascular diseases complicated by AS, Z-LIG exerts practical neuroprotective effects in ischemic stroke (IS), transient ischemic attack (TIA), and vascular dementia (VaD) through anti-neuroinflammatory, anti-oxidation, anti-neuronal apoptosis, protection of the blood-brain barrier, promotion of mitochondrial division and angiogenesis, improvement of cholinergic activity, inhibition of astrocyte proliferation, and endoplasmic reticulum stress. This paper aims to provide a basis for subsequent studies of Z-LIG in the prevention and treatment of AS and its cerebrovascular complications and, thus, to promote the development of interventional drugs for AS.

PRDX1 Interfering Peptide Disrupts Amino Acids 70-90 of PRDX1 to Inhibit the TLR4/NF-κB Signaling Pathway and Attenuate Neuroinflammation and Ischemic Brain Injury

Ischemic stroke ranks among the leading causes of death and disability in humans and is accompanied by motor and cognitive impairment. However, the precise mechanisms underlying injury after stroke and effective treatment strategies require further investigation. Peroxiredoxin-1 (PRDX1) triggers an extensive inflammatory cascade that plays a pivotal role in the pathology of ischemic stroke, resulting in severe brain damage from activated microglia. In the present study, we used molecular dynamics simulation and nuclear magnetic resonance to detect the interaction between PRDX1 and a specific interfering peptide. We used behavioral, morphological, and molecular experimental methods to demonstrate the effect of PRDX1-peptide on cerebral ischemia-reperfusion (I/R) in mice and to investigate the related mechanism. We found that PRDX1-peptide bound specifically to PRDX1 and improved motor and cognitive functions in I/R mice. In addition, pretreatment with PRDX1-peptide reduced the infarct area and decreased the number of apoptotic cells in the penumbra. Furthermore, PRDX1-peptide inhibited microglial activation and downregulated proinflammatory cytokines including IL-1β, IL-6, and TNF-α through inhibition of the TLR4/NF-κB signaling pathway, thereby attenuating ischemic brain injury. Our findings clarify the precise mechanism underlying PRDX1-induced inflammation after ischemic stroke and suggest that the PRDX1-peptide can significantly alleviate the postischemic inflammatory response by interfering with PRDX1 amino acids 70-90 and thereby inhibiting the TLR4/NF-κB signaling pathway. Our study provides a theoretical basis for a new therapeutic strategy to treat ischemic stroke.

Lung-resident alveolar macrophages regulate the timing of breast cancer metastasis

Breast disseminated cancer cells (DCCs) can remain dormant in the lungs for extended periods, but the mechanisms limiting their expansion are not well understood. Research indicates that tissue-resident alveolar macrophages suppress breast cancer metastasis in lung alveoli by inducing dormancy. Through ligand-receptor mapping and intravital imaging, it was found that alveolar macrophages express transforming growth factor (TGF)-β2. This expression, along with persistent macrophage-cancer cell interactions via the TGF-βRIII receptor, maintains cancer cells in a dormant state. Depleting alveolar macrophages or losing the TGF-β2 receptor in cancer cells triggers metastatic awakening. Aggressive breast cancer cells are either suppressed by alveolar macrophages or evade this suppression by avoiding interaction and downregulating the TGF-β2 receptor. Restoring TGF-βRIII in aggressive cells reinstates TGF-β2-mediated macrophage growth suppression. Thus, alveolar macrophages act as a metastasis immune barrier, and downregulation of TGF-β2 signaling allows cancer cells to overcome macrophage-mediated growth suppression.

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.

The plasma-soluble CSF1R level is a promising prognostic indicator for pediatric Langerhans cell histiocytosis

Langerhans cell histiocytosis (LCH) is a rare hematologic neoplasm characterized by the clonal proliferation of Langerhans-like cells. Colony-stimulating factor 1 receptor (CSF1R) is a membrane-bound receptor that is highly expressed in LCH cells and tumor-associated macrophages. In this study, a soluble form of CSF1R protein (sCSF1R) was identified by plasma proteome profiling, and its role in evaluating LCH prognosis was explored. We prospectively measured plasma sCSF1R levels in 104 LCH patients and 10 healthy children using ELISA. Plasma sCSF1R levels were greater in LCH patients than in healthy controls (p < .001) and significantly differed among the three disease extents, with the highest level in MS RO+ LCH patients (p < .001). Accordingly, immunofluorescence showed the highest level of membrane-bound CSF1R in MS RO+ patients. Furthermore, the plasma sCSF1R concentration at diagnosis could efficiently predict the prognosis of LCH patients treated with standard first-line treatment (AUC = 0.782, p < .001). Notably, dynamic monitoring of sCSF1R levels could predict relapse early in patients receiving BRAF inhibitor treatment. In vitro drug sensitivity data showed that sCSF1R increased resistance to Ara-C in THP-1 cells expressing ectopic BRAF-V600E. Overall, the plasma sCSF1R level at diagnosis and during follow-up is of great clinical importance in pediatric LCH patients.

Hepatocytes-derived Prdx1 regulates macrophage phenotypes via TLR4 activation in acute liver injury

Acute liver injury (ALI) is a significant causative factor for multiple hepatic diseases. The excessive inflammatory response triggers proinflammatory immune cells recruitment, infiltration and differentiation, further contributing to inflammatory injuries in liver. As a proinflammatory factor, circulating Peroxiredoxin 1 (Prdx1) is elevated in ALI patients and mice. In this study, through carbon tetrachloride (CCl4) and cecal puncture and ligation (CLP)-induced liver injury mice model, we found hepatocytes-derived Prdx1 expression was increased in ALI. After AAV8-Prdx1-mediated Prdx1 knockdown, CCl4 and CLP-induced ALI was alleviated, along with the reduced proinflammatory cytokines, suppressed myeloid cells recruitment, decreased proportions of hepatic macrophages and neutrophils, restrained proinflammatory macrophage differentiation and infiltration. Mechanistically, hepatocyte-derived Prdx1 regulated macrophages through paracrine activation of the TLR4 signal. Our data support the immune and inflammatory regulatory role of Prdx1 in ALI pathological process to suggest its potential therapeutic application and clinical value.

Paracrine Signaling Mediated by the Cytosolic Tryparedoxin Peroxidase of Trypanosoma cruzi

Peroxiredoxins are abundant and ubiquitous proteins that participate in different cellular functions, such as oxidant detoxification, protein folding, and intracellular signaling. Under different cellular conditions, peroxiredoxins can be secreted by different parasites, promoting the induction of immune responses in hosts. In this work, we demonstrated that the cytosolic tryparedoxin peroxidase of Trypanosoma cruzi (cTXNPx) is secreted by epimastigotes and trypomastigotes associated with extracellular vesicles and also as a vesicle-free protein. By confocal microscopy, we show that cTXNPx can enter host cells by an active mechanism both through vesicles and as a recombinant protein. Transcriptomic analysis revealed that cTXNPx induces endoplasmic reticulum stress and interleukin-8 expression in epithelial cells. This analysis also suggested alterations in cholesterol metabolism in cTXNPx-treated cells, which was confirmed by immunofluorescence showing the accumulation of LDL and the induction of LDL receptors in both epithelial cells and macrophages. BrdU incorporation assays and qPCR showed that cTXNPx has a mitogenic, proliferative, and proinflammatory effect on these cells in a dose-dependent manner. Importantly, we also demonstrated that cTXNPx acts as a paracrine virulence factor, increasing the susceptibility to infection in cTXNPx-pretreated epithelial cells by approximately 40%. Although the results presented in this work are from in vitro studies and likely underestimate the complexity of parasite-host interactions, our work suggests a relevant role for this protein in establishing infection.

PRDX1 Cys52Ser variant alleviates nonalcoholic steatohepatitis by reducing inflammation in mice

OBJECTIVE

Peroxiredoxin 1 (PRDX1) is a peroxidase and guards against oxidative stress by scavenging intracellular peroxides, whereas it also has been shown to stimulate inflammatory response by functioning as a chaperone protein. The potential in vivo link between PRDX1's peroxidase activity and its pro-inflammatory activity remains elusive.

METHODS

We generated peroxidase-dead PRDX1 variant mice by mutating its peroxidatic cysteine at 52 (Cys52) to serine, here referred to as PRDX1Cys52Ser. Trx-TrxR-NADPH coupled activity assay was applied to evaluate the peroxidase activity of global PRDX in PRDX1Cys52Ser variant mice. PRDX1Cys52Ser mice and their wild-type littermates were subjected to western diet or methionine and choline deficient diet feeding. NASH phenotypes were assessed through different analyses including physiological measurements, immunohistochemical staining, and quantitative PCR (qPCR). RNA sequencing, qPCR and western blotting were used to reveal and validate any changes in the signaling pathways responsible for the altered NASH phenotypes observed between WT and PRDX1Cys52Ser variant mice.

RESULTS

PRDX1Cys52Ser variant mice showed impaired global PRDX peroxidase activity and reduced susceptibility to diet-induced NASH and liver fibrosis. Mechanistically, PRDX1 Cys52Ser variant suppressed NF-κB signaling and STAT1 signaling pathways that are known to promote inflammation and NASH.

CONCLUSION

The peroxidatic Cys52 of PRDX1 is required for its pro-inflammatory activity in vivo. This study further suggests that PRDX1 may play dual but opposing roles in NASH.

MyD88-dependent Toll-like receptor 2 signaling modulates macrophage activation on lysate-adsorbed Teflon™ AF surfaces in an in vitro biomaterial host response model

The adsorbed protein layer on an implanted biomaterial surface is known to mediate downstream cell-material interactions that drive the host response. While the adsorption of plasma-derived proteins has been studied extensively, the adsorption of damage-associated molecular patterns (DAMPs) derived from damaged cells and matrix surrounding the implant remains poorly understood. Previously, our group developed a DAMP-adsorption model in which 3T3 fibroblast lysates were used as a complex source of cell-derived DAMPs and we demonstrated that biomaterials with adsorbed lysate potently activated RAW-Blue macrophages via Toll-like receptor 2 (TLR2). In the present study, we characterized the response of mouse bone marrow derived macrophages (BMDM) from wildtype (WT), TLR2-/- and MyD88-/- mice on Teflon™ AF surfaces pre-adsorbed with 10% plasma or lysate-spiked plasma (10% w/w total protein from 3T3 fibroblast lysate) for 24 hours. WT BMDM cultured on adsorbates derived from 10% lysate in plasma had significantly higher gene and protein expression of IL-1β, IL-6, TNF-α, IL-10, RANTES/CCL5 and CXCL1/KC, compared to 10% plasma-adsorbed surfaces. Furthermore, the upregulation of pro-inflammatory cytokine and chemokine expression in the 10% lysate in plasma condition was attenuated in TLR2-/- and MyD88-/- BMDM. Proteomic analysis of the adsorbed protein layers showed that even this relatively small addition of lysate-derived proteins within plasma (10% w/w) caused a significant change to the adsorbed protein profile. The 10% plasma condition had fibrinogen, albumin, apolipoproteins, complement, and fibronectin among the top 25 most abundant proteins. While proteins layers generated from 10% lysate in plasma retained fibrinogen and fibronectin among the top 25 proteins, there was a disproportionate increase in intracellular proteins, including histones, tubulins, actins, and vimentin. Furthermore, we identified 7 DAMPs or DAMP-related proteins enriched in the 10% plasma condition (fibrinogen, apolipoproteins), compared to 39 DAMPs enriched in the 10% lysate in plasma condition, including high mobility group box 1 and histones. Together, these findings indicate that DAMPs and other intracellular proteins readily adsorb to biomaterial surfaces in competition with plasma proteins, and that adsorbed DAMPs induce an inflammatory response in adherent macrophages that is mediated by the MyD88-dependent TLR2 signaling pathway.

Proteomics of the astrocyte secretome reveals changes in their response to soluble oligomeric Aβ

Astrocytes associate with amyloid plaques in Alzheimer's disease (AD). Astrocytes react to changes in the brain environment, including increasing concentrations of amyloid-β (Aβ). However, the precise response of astrocytes to soluble small Aβ oligomers at concentrations similar to those present in the human brain has not been addressed. In this study, we exposed astrocytes to media from neurons that express the human amyloid precursor protein (APP) transgene with the double Swedish mutation (APPSwe), and which contains APP-derived fragments, including soluble human Aβ oligomers. We then used proteomics to investigate changes in the astrocyte secretome. Our data show dysregulated secretion of astrocytic proteins involved in the extracellular matrix and cytoskeletal organization and increase secretion of proteins involved in oxidative stress responses and those with chaperone activity. Several of these proteins have been identified in previous transcriptomic and proteomic studies using brain tissue from human AD and cerebrospinal fluid (CSF). Our work highlights the relevance of studying astrocyte secretion to understand the brain response to AD pathology and the potential use of these proteins as biomarkers for the disease.

Peroxiredoxin 1 aggravates acute kidney injury by promoting inflammation through Mincle/Syk/NF-κB signaling

Damage-associated molecular patterns (DAMPs) are a cause of acute kidney injury (AKI). Our knowledge of these DAMPs remains incomplete. Here, we report serum peroxiredoxin 1 (Prdx1) as a novel DAMP for AKI. Lipopolysaccharide (LPS) and kidney ischemia/reperfusion injury instigated AKI with concurrent increases in serum Prdx1 and reductions of Prdx1 expression in kidney tubular epithelial cells. Genetic knockout of Prdx1 or use of a Prdx1-neutralizing antibody protected mice from AKI and this protection was impaired by introduction of recombinant Prdx1 (rPrdx1). Mechanistically, lipopolysaccharide increased serum and kidney proinflammatory cytokines, macrophage infiltration, and the content of M1 macrophages. All these events were suppressed in Prdx1-/- mice and renewed upon introduction of rPrdx1. In primary peritoneal macrophages, rPrdx1 induced M1 polarization, activated macrophage-inducible C-type lectin (Mincle) signaling, and enhanced proinflammatory cytokine production. Prdx1 interacted with Mincle to initiate acute kidney inflammation. Of note, rPrdx1 upregulated Mincle and the spleen tyrosine kinase Syk system in the primary peritoneal macrophages, while knockdown of Mincle abolished the increase in activated Syk. Additionally, rPrdx1 treatment enhanced the downstream events of Syk, including transcription factor NF-κB signaling pathways. Furthermore, serum Prdx1 was found to be increased in patients with AKI; the increase of which was associated with kidney function decline and inflammatory biomarkers in patient serum. Thus, kidney-derived serum Prdx1 contributes to AKI at least in part by activating Mincle signaling and downstream pathways.

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.

Surface modification of fibroblasts with peroxiredoxin-1-loaded polymeric microparticles increases cell mobility, resistance to oxidative stress and collagen I production

Modification of the cell surface with artificial nano- and microparticles (also termed "cellular backpacks") containing biologically active payloads usually enables drug targeting via harnessing intrinsic cell tropism to the sites of injury. In some cases, using cells as delivery vehicles leads to improved pharmacokinetics due to extended circulation time of cell-immobilized formulations. Another rationale for particle attachment to cells is augmentation of desirable cellular functions and cell proliferation in response to release of the particle contents. In this study, we conjugated poly(lactic-co-glycolic acid) (PLGA) microparticles loaded with multifunctional antioxidant enzyme peroxiredoxin-1 (Prx1) to the surface of fibroblasts. The obtained microparticles were uniform in size and demonstrated sustained protein release. We found that the released Prx1 maintains its signaling activity resulting in macrophage activation, as indicated by TNFα upregulation and increase in ROS generation. Functionalization of fibroblasts with PLGA/Prx1 microparticles via EDC/sulfo-NHS coupling reaction did not affect cell viability but increased cell migratory properties and collagen I production. Moreover, PLGA/Prx1 backpacks increased resistance of fibroblasts to oxidative stress and attenuated cell senescence. In summary, we have developed a novel approach of fibroblast modification to augment their biological properties, which can be desirable for wound repair, cosmetic dermatology, and tissue engineering.

Structure-based analysis and rational design of human peroxiredoxin-1's C-terminus-derived peptides to target sulfiredoxin-1 in pancreatic cancer

Human peroxiredoxin (PRX) family of antioxidant enzymes reduces hydrogen peroxide and alkyl hydroperoxide involved in the redox signaling, among which the widely documented PRX1 is a versatile molecule regulating cell growth, differentiation and apoptosis, and has been implicated in the tumorigensis of pancreatic cancer. In this study, we systematically examined the complex crystal structure of PRX1 with its cognate interacting partner sulfiredoxin-1 (SRX1) at molecular level, and found that the PRX1-SRX1 association is a typical peptide-mediated protein-protein interaction, where a 18-mer C-terminal tail (CTT) segment of PRX1 was identified to be primarily responsible for the interaction, which contributes ~80% and ~ 55% to the total binding potency of SRX1 to PRX1 monomer and homodimer, respectively. We also demonstrated that the SRX1 exhibits a strong global selectivity for PRX1 CTT tail over other PRX family proteins. Next, the intermolecular interaction between PRX1 CTT tail and SRX1 was investigated at structural, energetic and dynamic levels, from which a 9-mer core region of PRX1 CTT tail was defined as the SRX1-binding hotspot. Biophysical assays substantiated that the CTT and CTTc peptides (out of PRX1 protein context) can bind in an independent manner and possess a close affinity to SRX1. Based on the CTTc sketch a computational combinatorial library consisting of 216 designed peptide derivatives was rationally generated, from which the top-5 hits were found to have comparable affinity with CTT peptide and improved affinity relative to CTTc peptide. They can be used as structurally reduced lead molecular entities to further develop new peptidic agents for therapeutic purpose to disrupt the native PRX1-SRX1 interaction by competing with PRX1 CTT tail for the peptide-binding pocket of SRX1.

Peroxiredoxin 4 Interacts With Domeless and Participates in Antibacterial Immune Response Through the JAK/STAT Pathway

The JAK/STAT pathway plays an important role in the development and immune responses of animals. In vertebrates, families of cytokines or growth factors act as activators of the JAK/STAT pathway; however, the activators for the JAK/STAT signaling pathway in arthropods are largely unknown. Herein we report a new ligand, peroxiredoxin 4 (Prx4), for the Domeless in the JAK/STAT pathway of shrimp Marsupenaeus japonicus. Prx4 was induced to secrete into the extracellular surroundings upon Vibrio challenge, which then facilitated the anti-Vibrio activity of shrimp by activating the phosphorylation and nuclear translocation of STAT and the expression of STAT-responsive antimicrobial peptides. Blocking the expression of Prx4 in vivo abrogated the activation of the JAK/STAT pathway by Vibrio infection, while injection of Prx4 protein activated the pathway. The interaction between Prx4 and Domeless was proved by immuno-precipitation and protein pull-down assays. Moreover, two cysteine residues in Prx4 that are critical for the interaction and Prx4’s anti-Vibrio role were identified, and the binding site in Domeless for Prx4 was proved to be the cytokine-binding homology module fragment. Taken together, our study revealed a new function for Prx4 enzyme and established a new enzyme-type ligand for the activation of the JAK/STAT pathway in an aquatic arthropod.

Immunity in Stroke: The Next Frontier

Translational stroke research has long been focusing on neuroprotective strategies to prevent secondary tissue injury and promote recovery after acute ischemic brain injury. The inflammatory response to stroke has more recently emerged as a key pathophysiological pathway contributing to stroke outcome. It is now accepted that the inflammatory response is functionally involved in all phases of the ischemic stroke pathophysiology. The immune response is therefore considered a breakthrough target for ischemic stroke treatment. On one side, stroke induces a local neuroinflammatory response, in which the inflammatory activation of glial, endothelial and brain-invading cells contributes to lesion progression after stroke. On the other side, ischemic brain injury perturbs systemic immune homeostasis and results in long-lasting changes of systemic immunity. Here, we briefly summarize current concepts in local neuroinflammation and the systemic immune responses after stroke, and highlight two promising therapeutic strategies for poststroke inflammation.

The Role of Peroxiredoxins in the Regulation of Sepsis

Oxidative stress, a result of a disturbance in redox homeostasis, is considered to be one of the main aggravating events in the pathogenesis of immune disorders. Peroxiredoxins (Prdxs) are an enzyme family that catalyzes the reduction of peroxides, including hydrogen peroxide, lipid peroxides, and nitrogen peroxides. Although the maintenance of cellular redox homeostasis through Prdxs is essential for surviving in adverse environments, Prdxs also participate in the regulation of cellular signal transduction by modulating the activities of a panel of molecules involved in the signal transduction process. Although Prdxs were discovered as intracellular anti-oxidative enzymes, recent research has revealed that Prdxs also play important roles in the extracellular milieu. Indeed, Prdxs have been shown to have the capacity to activate immune cells through ligation with innate immune receptors such as toll-like receptors (TLRs). In this review, we will summarize the intracellular as well as extracellular roles of Prdxs for and against the pathogenesis of inflammatory disorders including sepsis, hemorrhagic shock, and drug-induced liver injury.

Innate Immunity as an Executor of the Programmed Death of Individual Organisms for the Benefit of the Entire Population

In humans, over-activation of innate immunity in response to viral or bacterial infections often causes severe illness and death. Furthermore, similar mechanisms related to innate immunity can cause pathogenesis and death in sepsis, massive trauma (including surgery and burns), ischemia/reperfusion, some toxic lesions, and viral infections including COVID-19. Based on the reviewed observations, we suggest that such severe outcomes may be manifestations of a controlled suicidal strategy protecting the entire population from the spread of pathogens and from dangerous pathologies rather than an aberrant hyperstimulation of defense responses. We argue that innate immunity may be involved in the implementation of an altruistic programmed death of an organism aimed at increasing the well-being of the whole community. We discuss possible ways to suppress this atavistic program by interfering with innate immunity and suggest that combating this program should be a major goal of future medicine.

Role of the Redox State of Human Peroxiredoxin-5 on Its TLR4-Activating DAMP Function

Human peroxiredoxin-5 (PRDX5) is a unique redox-sensitive protein that plays a dual role in brain ischemia-reperfusion injury. While intracellular PRDX5 has been reported to act as a neuroprotective antioxidative enzyme by scavenging peroxides, once released extracellularly from necrotic brain cells, the protein aggravates neural cell death by inducing expression of proinflammatory cytokines in macrophages through activation of Toll-like receptor (TLR) 2 (TLR2) and 4 (TLR4). Although recent evidence showed that PRDX5 was able to interact directly with TLR4, little is known regarding the role of the cysteine redox state of PRDX5 on its DAMP function. To gain insights into the role of PRDX5 redox-active cysteine residues in the TLR4-dependent proinflammatory activity of the protein, we used a recombinant human PRDX5 in the disulfide (oxidized) form and a mutant version lacking the peroxidatic cysteine, as well as chemically reduced and hyperoxidized PRDX5 proteins. We first analyzed the oxidation state and oligomerization profile by Western blot, mass spectrometry, and SEC-MALS. Using ELISA, we demonstrate that the disulfide bridge between the enzymatic cysteines is required to allow improved TLR4-dependent IL-8 secretion. Moreover, single-molecule force spectroscopy experiments revealed that TLR4 alone is not sufficient to discriminate the different PRDX5 redox forms. Finally, flow cytometry binding assays show that disulfide PRDX5 has a higher propensity to bind to the surface of living TLR4-expressing cells than the mutant protein. Taken together, these results demonstrate the importance of the redox state of PRDX5 cysteine residues on TLR4-induced inflammation.

AIM/CD5L attenuates DAMPs in the injured brain and thereby ameliorates ischemic stroke

The sterile inflammation caused by damage-associated molecular patterns (DAMPs) worsens the prognosis following primary injury such as ischemic stroke. However, there are no effective treatments to regulate DAMPs. Here, we report that AIM (or CD5L) protein reduces sterile inflammation by attenuating DAMPs and that AIM administration ameliorates the deleterious effects of ischemic stroke. AIM binds to DAMPs via charge-based interactions and disulfide bond formation. This AIM association promotes the phagocytic removal of DAMPs and neutralizes DAMPs by impeding their binding to inflammatory receptors. In experimental stroke, AIM-deficient mice exhibit severe neurological damage and higher mortality with greater levels of DAMPs and associated inflammation in the brain than wild-type mice, in which brain AIM levels increase following stroke onset. Recombinant AIM administration reduces sterile inflammation in the infarcted region, leading to a profound reduction of animal mortality. Our findings provide a basis for the therapies targeting DAMPs to improve ischemic stroke.

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.

Extracellular Vesicles under Oxidative Stress Conditions: Biological Properties and Physiological Roles

Under physio-pathological conditions, cells release membrane-surrounded structures named Extracellular Vesicles (EVs), which convey their molecular cargo to neighboring or distant cells influencing their metabolism. Besides their involvement in the intercellular communication, EVs might represent a tool used by cells to eliminate unnecessary/toxic material. Here, we revised the literature exploring the link between EVs and redox biology. The first proof of this link derives from evidence demonstrating that EVs from healthy cells protect target cells from oxidative insults through the transfer of antioxidants. Oxidative stress conditions influence the release and the molecular cargo of EVs that, in turn, modulate the redox status of target cells. Oxidative stress-related EVs exert both beneficial or harmful effects, as they can carry antioxidants or ROS-generating enzymes and oxidized molecules. As mediators of cell-to-cell communication, EVs are also implicated in the pathophysiology of oxidative stress-related diseases. The review found evidence that numerous studies speculated on the role of EVs in redox signaling and oxidative stress-related pathologies, but few of them unraveled molecular mechanisms behind this complex link. Thus, the purpose of this review is to report and discuss this evidence, highlighting that the analysis of the molecular content of oxidative stress-released EVs (reminiscent of the redox status of originating cells), is a starting point for the use of EVs as diagnostic and therapeutic tools in oxidative stress-related diseases.

In silico designing of vaccine candidate against Clostridium difficile

Clostridium difficile is a spore-forming gram-positive bacterium, recognized as the primary cause of antibiotic-associated nosocomial diarrhoea. Clostridium difficile infection (CDI) has emerged as a major health-associated infection with increased incidence and hospitalization over the years with high mortality rates. Contamination and infection occur after ingestion of vegetative spores, which germinate in the gastro-intestinal tract. The surface layer protein and flagellar proteins are responsible for the bacterial colonization while the spore coat protein, is associated with spore colonization. Both these factors are the main concern of the recurrence of CDI in hospitalized patients. In this study, the CotE, SlpA and FliC proteins are chosen to form a multivalent, multi-epitopic, chimeric vaccine candidate using the immunoinformatics approach. The overall reliability of the candidate vaccine was validated in silico and the molecular dynamics simulation verified the stability of the vaccine designed. Docking studies showed stable vaccine interactions with Toll‐Like Receptors of innate immune cells and MHC receptors. In silico codon optimization of the vaccine and its insertion in the cloning vector indicates a competent expression of the modelled vaccine in E. coli expression system. An in silico immune simulation system evaluated the effectiveness of the candidate vaccine to trigger a protective immune response.

Phthalide derivative CD21 attenuates tissue plasminogen activator-induced hemorrhagic transformation in ischemic stroke by enhancing macrophage scavenger receptor 1-mediated DAMP (peroxiredoxin 1) clearance

BACKGROUND

Hemorrhagic transformation (HT) is a critical issue in thrombolytic therapy in acute ischemic stroke. Damage-associated molecular pattern (DAMP)-stimulated sterile neuroinflammation plays a crucial role in the development of thrombolysis-associated HT. Our previous study showed that the phthalide derivative CD21 attenuated neuroinflammation and brain injury in rodent models of ischemic stroke. The present study explored the effects and underlying mechanism of action of CD21 on tissue plasminogen activator (tPA)-induced HT in a mouse model of transient middle cerebral artery occlusion (tMCAO) and cultured primary microglial cells.

METHODS

The tMCAO model was induced by 2 h occlusion of the left middle cerebral artery with polylysine-coated sutures in wildtype (WT) mice and macrophage scavenger receptor 1 knockout (MSR1^-/-) mice. At the onset of reperfusion, tPA (10 mg/kg) was intravenously administered within 30 min, followed by an intravenous injection of CD21 (13.79 mg/kg/day). Neuropathological changes were detected in mice 3 days after surgery. The effect of CD21 on phagocytosis of the DAMP peroxiredoxin 1 (Prx1) in lysosomes was observed in cultured primary microglial cells from brain tissues of WT and MSR1^-/- mice.

RESULTS

Seventy-two hours after brain ischemia, CD21 significantly attenuated neurobehavioral dysfunction and infarct volume. The tPA-infused group exhibited more severe brain dysfunction and hemorrhage. Compared with tPA alone, combined treatment with tPA and CD21 significantly attenuated ischemic brain injury and hemorrhage. Combined treatment significantly decreased Evans blue extravasation, matrix metalloproteinase 9 expression and activity, extracellular Prx1 content, proinflammatory cytokine mRNA levels, glial cells, and Toll-like receptor 4 (TLR4)/nuclear factor κB (NF-κB) pathway activation and increased the expression of tight junction proteins (zonula occludens-1 and claudin-5), V-maf musculoaponeurotic fibrosarcoma oncogene homolog B, and MSR1. MSR1 knockout significantly abolished the protective effect of CD21 against tPA-induced HT in tMCAO mice. Moreover, the CD21-induced phagocytosis of Prx1 was MSR1-dependent in cultured primary microglial cells from WT and MSR1^-/- mice, respectively.

CONCLUSION

The phthalide derivative CD21 attenuated tPA-induced HT in acute ischemic stroke by promoting MSR1-induced DAMP (Prx1) clearance and inhibition of the TLR4/NF-κB pathway and neuroinflammation.

Peroxiredoxins-The Underrated Actors during Virus-Induced Oxidative Stress

Enhanced production of reactive oxygen species (ROS) triggered by various stimuli, including viral infections, has attributed much attention in the past years. It has been shown that different viruses that cause acute or chronic diseases induce oxidative stress in infected cells and dysregulate antioxidant its antioxidant capacity. However, most studies focused on catalase and superoxide dismutases, whereas a family of peroxiredoxins (Prdx), the most effective peroxide scavengers, were given little or no attention. In the current review, we demonstrate that peroxiredoxins scavenge hydrogen and organic peroxides at their physiological concentrations at various cell compartments, unlike many other antioxidant enzymes, and discuss their recycling. We also provide data on the regulation of their expression by various transcription factors, as they can be compared with the imprint of viruses on transcriptional machinery. Next, we discuss the involvement of peroxiredoxins in transferring signals from ROS on specific proteins by promoting the oxidation of target cysteine groups, as well as briefly demonstrate evidence of nonenzymatic, chaperone, functions of Prdx. Finally, we give an account of the current state of research of peroxiredoxins for various viruses. These data clearly show that Prdx have not been given proper attention despite all the achievements in general redox biology.

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.

Withania somnifera (L.) Dunal: Opportunity for Clinical Repurposing in COVID-19 Management

As the COVID-19 pandemic is progressing, the therapeutic gaps in conventional management have highlighted the need for the integration of traditional knowledge systems with modern medicine. Ayurvedic medicines, especially Ashwagandha (Withania somnifera (L.) Dunal, WS), may be beneficial in the management of COVID-19. WS is a widely prescribed Ayurvedic botanical known as an immunomodulatory, antiviral, anti-inflammatory, and adaptogenic agent. The chemical profile and pharmacological activities of WS have been extensively reported. Several clinical studies have reported its safety for use in humans. This review presents a research synthesis of in silico, in vitro, in vivo, and clinical studies on Withania somnifera (L.) Dunal (WS) and discusses its potential for prophylaxis and management of COVID-19. We have collated the data from studies on WS that focused on viral infections (HIV, HSV, H1N1 influenza, etc.) and noncommunicable diseases (hypertension, diabetes, cancer, etc.). The experimental literature indicates that WS has the potential for 1) maintaining immune homeostasis, 2) regulating inflammation, 3) suppressing pro-inflammatory cytokines, 4) organ protection (nervous system, heart, lung, liver, and kidney), and 5) anti-stress, antihypertensive, and antidiabetic activities. Using these trends, the review presents a triangulation of Ayurveda wisdom, pharmacological properties, and COVID-19 pathophysiology ranging from viral entry to end-stage acute respiratory distress syndrome (ARDS). The review proposes WS as a potential therapeutic adjuvant for various stages of COVID-19 management. WS may also have beneficial effects on comorbidities associated with the COVID-19. However, systematic studies are needed to realize the potential of WS for improving clinical outcome of patients with COVID-19.

The cytosolic tryparedoxin peroxidase from Trypanosoma cruzi induces a pro-inflammatory Th1 immune response in a peroxidatic cysteine-dependent manner

Trypanosoma cruzi cytosolic tryparedoxin peroxidase (c-TXNPx) is a 2-Cys peroxiredoxin (Prx) with an important role in detoxifying host cell oxidative molecules during parasite infection. c-TXNPx is a virulence factor, as its overexpression enhances parasite infectivity and resistance to exogenous oxidation. As Prxs from other organisms possess immunomodulatory properties, we studied the effects of c-TXNPx in the immune response and analysed whether the presence of the peroxidatic cysteine is necessary to mediate these properties. To this end, we used a recombinant c-TXNPx and a mutant version (c-TXNPxC52S) lacking the peroxidatic cysteine. We first analysed the oligomerization profile, oxidation state and peroxidase activity of both proteins by gel filtration, Western blot and enzymatic assay, respectively. To investigate their immunological properties, we analysed the phenotype and functional activity of macrophage and dendritic cells and the T-cell response by flow cytometry after injection into mice. Our results show that c-TXNPx, but not c-TXNPxC52S, induces the recruitment of IL-12/23p40-producing innate antigen-presenting cells and promotes a strong specific Th1 immune response. Finally, we studied the cellular and humoral immune response developed in the context of parasite natural infection and found that only wild-type c-TXNPx induces proliferation and high levels of IFN-γ secretion in PBMC from chronic patients without demonstrable cardiac manifestations. In conclusion, we demonstrate that c-TXNPx possesses pro-inflammatory properties that depend on the presence of peroxidatic cysteine that is essential for peroxidase activity and quaternary structure of the protein and could contribute to rational design of immune-based strategies against Chagas disease.

Identification of altered protein expression in major depressive disorder and bipolar disorder patients using liquid chromatography-tandem mass spectrometry

Emerging high-throughput proteomic technologies have recently been considered as a powerful means of identifying substrates involved in mood disorders. We performed proteomic profiling using liquid chromatography-tandem mass spectrometry to identify dysregulated proteins in plasma samples of 42 and 45 patients with major depressive disorder (MDD) and bipolar disorder (BD), respectively, in comparison to 51 healthy controls (HCs). Fourteen and six proteins in MDD and BD patients, respectively, were differentially expressed compared to HCs, among which coagulation factor XIII A chain (F13A1), platelet basic protein (PPBP), platelet facor 4 (PF4), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and thymosin beta-4 (TMSB4X) were altered in both disorders. For proteins dysregulated in both, except F13A1, higher fold changes were observed in MDD than in BD patients. These findings may help identify candidate biomarkers of mood disorders and elucidate their underlying pathophysiology and biochemical abnormalities.

Peroxiredoxins wear many hats: Factors that fashion their peroxide sensing personalities

Peroxiredoxins (Prdxs) sense and assess peroxide levels, and signal through protein interactions. Understanding the role of the multiple structural and post-translational modification (PTM) layers that tunes the peroxiredoxin specificities is still a challenge. In this review, we give a tabulated overview on what is known about human and bacterial peroxiredoxins with a focus on structure, PTMs, and protein-protein interactions. Armed with numerous cellular and atomic level experimental techniques, we look at the future and ask ourselves what is still needed to give us a clearer view on the cellular operating power of Prdxs in both stress and non-stress conditions.

Fish natural killer enhancing factor-A (NKEF-A) enhance cytotoxicity of nonspecific cytotoxic cells against bacterial infection

Natural killer enhancing factor (NKEF)-A/B is a member of Peroxiredoxin (Prxs) family, which is named for the function of enhancing NK cells activity. NKEF also plays essential roles in multiple physiology/pathology processes including inflammation regulation, cancer development and redox reactions. However, the regulatory effects of fish NKEF on immune cells remain largely unknown. In this study, the full-length cDNA of NKEF-A (Accession No. MK584553, designated as On-NKEF-A) was identified from Nile tilapia (Oreochromis niloticus). On-NKEF-A encoded a 198 amino acid peptide with molecular mass of 22.085 kDa. On-NKEF-A protein contained a typical 2-Cys family domain, two active sites (51aa and 172aa) that were conserved in mammals, birds, amphibians and fish. Phylogenetic analysis showed that On-NKEF-A had the closest relationship with Zebra mbuna (Maylandia zebra) NKEF. The On-NKEF-A transcription was present in all examined tissues or organs. And the relative high expression levels of On-NKEF-A was found in head kidney leucocytes and nonspecific cytotoxic cells (NCC). After Streptococcus agalactiae stimulation, On-NKEF-A was significantly up-regulated in head kidney, spleen, gill and skin. Also, On-NKEF-A was markedly induced post S. agalactiae, LPS and poly I:C stimulation in head kidney-derived NCC. Moreover, On-NKEF-A was mainly distributed in cytoplasm of fathead minnow cells (FHM cells). The further in vitro analysis found that the recombinant protein of On-NKEF-A (rOn-NKEF-A) could induce the expression of various molecular markers of B cells, macrophages and NCC, enhanced the cytotoxicity of NCC via increasing the effectors expression. The present data collectively indicate that On-NKEF-A participates in anti-bacterial immune response via regulating NCC activity, which will provide new ideas to further explore the defense mechanism of fish against bacteria.

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.

Autophagy Activated by Peroxiredoxin of Entamoeba histolytica

Autophagy, an evolutionarily conserved mechanism to remove redundant or dangerous cellular components, plays an important role in innate immunity and defense against pathogens, which, in turn, can regulate autophagy to establish infection within a host. However, for Entamoeba histolytica, an intestinal protozoan parasite causing human amoebic colitis, the interaction with the host cell autophagy mechanism has not been investigated. In this study, we found that E. histolytica peroxiredoxin (Prx), an antioxidant enzyme critical for parasite survival during the invasion of host tissues, could activate autophagy in macrophages. The formation of autophagosomes in macrophages treated with recombinant Prx of E. histolytica for 24 h was revealed by immunofluorescence and immunoblotting in RAW264.7 cells and in mice. Prx was cytotoxic for RAW264.7 macrophages after 48-h treatment, which was partly attributed to autophagy-dependent cell death. RNA interference experiments revealed that Prx induced autophagy mostly through the toll-like receptor 4 (TLR4)-TIR domain-containing adaptor-inducing interferon (TRIF) pathway. The C-terminal part of Prx comprising 100 amino acids was the key functional domain to activate autophagy. These results indicated that Prx of E. histolytica could induce autophagy and cytotoxic effects in macrophages, revealing a new pathogenic mechanism activated by E. histolytica in host cells.

Peroxiredoxin 1 - Multifunctional antioxidant enzyme, protects from oxidative damages and increases the survival rate of mice exposed to total body irradiation

PURPOSE

Peroxiredoxin 1 (Prx1) is known to be a multifunctional antioxidant enzyme playing an essential role in protecting the organism against oxidative stress. We hypothesized that administration of exogenous recombinant Prx1 may provide additional protection of the mammalian organism during the development of acute oxidative stress induced by ionizing radiation. Hence, the aim of the present work was to study the radioprotective properties of exogenous Prx1.

MATERIALS AND METHODS

Recombinant Prx1 was obtained by genetic engineering. The properties of Prx1 were studied using physicochemical methods. An immunoblotting and ELISA were used for the determination of the level of endogenous and exogenous Prx1 in animal blood. The survival rate of irradiated animals was assessed for 30 days with various modes of administration (intraperitoneal, intramuscular, intravenously) Prx1. Using a hematological analyzer and microscopic analysis, the changes in the level of leukocytes and platelets were assessed in animals that received and did not receive an intravenous injection of Prx1 before irradiation. Genoprotective properties of Prx1 were confirmed by micronucleus test. Real-time PCR was used to investigate the effect of Prx1 on the expression of genes involved in response to oxidative stress.

RESULTS

Recombinant Prx1 was shown to significantly reduce oxidative damage to biological macromolecules. Prx1 is an effective radioprotector which decreases the severity of radiation-induced leuko- and thrombocytopenia, plus protects bone marrow cells from damage. The half-life of Prx1 in the bloodstream is more than 1 h, while within 1 h there is a loss of the antioxidant activity of Prx1 by almost 50%, which limits its use long (2 h) before irradiation. The introduction of Prx1 after irradiation has no significant radiomitigating effect. The most effective way of using Prx1 is intravenous administration shortly (15-30 min) before exposure to ionizing radiation, with a dose reduction factor of 1.3. Under the action of ionizing radiation a dose-dependent appearance of endogenous Prx1 in the bloodstream was also observed. The appearance of Prx1 in the bloodstream alters the expression of stress response genes (especial antioxidant response and DNA repair) in the cells of red bone marrow, promoting the activation of repair processes.

CONCLUSION

The recombinant Prx1 can be considered as an effective radioprotector for minimizing the risks of injury of animal's body by ionizing radiation.

Cellular Target Proteome in Breast Cancer Cells of an Oplopane Sesquiterpenoid Isolated from Tussilago farfara

Tussilago farfara is a traditional herbal medicine used to treat coughs, bronchitis, and asthma. Its bioactive compounds include sesquiterpenoids with anti-inflammatory, antiproliferative, neuroprotective, and other effects. Biochemical studies have highlighted the mechanisms of action, but the investigations of related molecular pathways have not specified direct molecular targets. Therefore, this study profiled cellular target proteins of a sesquiterpenoid isolated from T. farfara using quantitative chemical proteomics in MDA-MB-231 and MCF-7 human breast cancer cells. Compound 8, 7β-(3'-ethyl-cis-crotonoyloxy)-1α-(2'-methyl butyryloxy)-3,14-dehydro-Z-notonipetranone, exhibited potent antiproliferative activity based on its α,β-unsaturated carbonyl moiety, and its potential cellular target proteins were identified using a compound 8-based clickable probe. Among >200 identified proteins, 17 showed enrichment ratios of >3 in both cell lines, while recombinant 14-3-3 protein zeta and peroxiredoxin-1 were verified using isothermic calorimetry and their alkylation sites. Considering the interaction between the α,β-unsaturated carbonyl moiety of compound 8 and cysteine residues of the proteins, peptides containing Cys25 and Cys94 of 14-3-3 protein zeta and Cys83 of peroxiredoxin-1 were significantly reduced by this sesquiterpene ester. Although the results did not elucidate the effects of compound 8 in breast cancer cells, identification of potential target proteins contributes to enhanced understanding of its antiproliferative and anti-inflammatory effects.

Full-length transcriptome sequencing combined with RNA-seq analysis revealed the immune response of fat greenling (Hexagrammos otakii) to Vibrio harveyi in early infection

Fat greenling (Hexagrammos otakii) is an important commercial marine fish species cultured in northeast Asia, but its available gene sequences are limited. Vibrio harveyi is a causative agent of vibriosis in fat greenling and also causes severe losses to the aquaculture industry in China. In order to obtain more high-quality transcript information and investigate the early immune response of fat greenling against V. harveyi, the fish were artificially infected with V. harveyi, and five sampling points were set within 48 h. Iso-Seq combined with RNA-Seq were applied in the comprehensive transcriptome analysis of V. harveyi-infected fat greenling. Total 42,225 consensus isoforms were successfully extracted from the result of Iso-Seq, and more than 19,000 ORFs were predicted. In addition, total three modules were identified by WGCNA which significantly positive correlated to the infection time, and the KEGG analysis showed that the immune-related genes in these modules mainly enriched in TLR signaling pathway, NF-κB signaling pathway and Endocytosis. The activation of inflammation and endocytosis was the most significant characteristics of fat greenling immune response during the early infection. Based on the WGCNA, a series of high-degree nodes in the networks were identified as hub genes. The protein structures of cold-inducible RNA-binding protein (CIRBP), poly [ADP-ribose] polymerase 1 (PARP1) and protein arginine N-methyl transferase 1 (PRMT1) were subsequently found to be highly conserved in vertebrate, and the gene expression pattern of CIRBP, PARP1, PRMT1 and a part of TLR/NF-κB pathway-related genes indicated that these proteins might have similar biological functions in regulation of inflammatory response in teleost fish. The results of this study provided the first systematical full-length transcriptome profile of fat greenling and characterized its immune responses in early infection of V. harvey, which will serve as the foundation for further exploring the molecular mechanism of immune defense against bacterial infection in fat greenling.

How the redox state regulates immunity

Oxidative stress is defined as an imbalance between the levels of reactive oxygen species (ROS) and antioxidant defences. The view of oxidative stress as a cause of cell damage has evolved over the past few decades to a much more nuanced view of the role of oxidative changes in cell physiology. This is no more evident than in the field of immunity, where oxidative changes are now known to regulate many aspects of the immune response, and inflammatory pathways in particular. Our understanding of redox regulation of immunity now encompasses not only increases in reactive oxygen and nitrogen species, but also changes in the activities of oxidoreductase enzymes. These enzymes are important regulators of immune pathways both via changes in their redox activity, but also via other more recently identified cytokine-like functions. The emerging picture of redox regulation of immune pathways is one of increasing complexity and while therapeutic targeting of the redox environment to treat inflammatory disease is a possibility, any such strategy is likely to be more nuanced than simply inhibiting ROS production.

Peri/Epicellular Thiol Oxidoreductases as Mediators of Extracellular Redox Signaling

Significance: Supracellular redox networks regulating cell-extracellular matrix (ECM) and organ system architecture merge with structural and functional (catalytic or allosteric) properties of disulfide bonds. This review addresses emerging evidence that exported thiol oxidoreductases (TORs), such as thioredoxin, protein disulfide isomerases (PDIs), quiescin sulfhydryl oxidases (QSOX)1, and peroxiredoxins, composing a peri/epicellular (pec)TOR pool, mediate relevant signaling. pecTOR functions depend mainly on kinetic and spatial regulation of thiol-disulfide exchange reactions governed by redox potentials, which are modulated by exported intracellular low-molecular-weight thiols, together conferring signal specificity. Recent Advances: pecTOR redox-modulates several targets including integrins, ECM proteins, surface molecules, and plasma components, although clear-cut documentation of direct effects is lacking in many cases. TOR catalytic pathways, displaying common patterns, culminate in substrate thiol reduction, oxidation, or isomerization. Peroxiredoxins act as redox/peroxide sensors, contrary to PDIs, which are likely substrate-targeted redox modulators. Emerging evidence suggests important pecTOR roles in patho(physio)logical processes, including blood coagulation, vascular remodeling, mechanosensing, endothelial function, immune responses, and inflammation. Critical Issues: Effects of pecPDIs supporting thrombosis/platelet activation have been well documented and reached the clinical arena. Roles of pecPDIA1 in vascular remodeling/mechanosensing are also emerging. Extracellular thioredoxin and pecPDIs redox-regulate immunoinflammation. Routes of TOR externalization remain elusive and appear to involve Golgi-independent routes. pecTORs are particularly accessible drug targets. Future Directions: Further understanding mechanisms of thiol redox reactions and developing assays for assessing pecTOR redox activities remain important research avenues. Also, addressing pecTORs as disease markers and achieving more efficient/specific drugs for pecTOR modulation are major perspectives for diagnostic/therapeutic improvements.

Comparative Study of Protective Action of Exogenous 2-Cys Peroxiredoxins (Prx1 and Prx2) Under Renal Ischemia-Reperfusion Injury

The pathogenesis of ischemia-reperfusion (I/R) injuries is based on oxidative stress caused by a sharp increase in the concentration of free radicals, reactive oxygen species (ROS) and secondary products of free radical oxidation of biological macromolecules during reperfusion. Application of exogenous antioxidants lowers the level of ROS in the affected tissues, suppresses or adjusts the course of oxidative stress, thereby substantially reducing the severity of I/R injury. We believe that the use of antioxidant enzymes may be the most promising line of effort since they possess higher efficiency than low molecular weight antioxidants. Among antioxidant enzymes, of great interest are peroxiredoxins (Prx1–6) which reduce a wide range of organic and inorganic peroxide substrates. In an animal model of bilateral I/R injury of kidneys (using histological, biochemical, and molecular biological methods) it was shown that intravenous administration of recombinant typical 2-Cys peroxiredoxins (Prx1 and Prx2) effectively reduces the severity of I/R damage, contributing to the normalization of the structural and functional state of the kidneys and an almost 2-fold increase in the survival of experimental animals. The use of recombinant Prx1 or Prx2 can be an efficient approach for the prevention and treatment of renal I/R injury.

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.

Proteomic profiling of yellow catfish (Pelteobagrus fulvidraco) skin mucus identifies differentially-expressed proteins in response to Edwardsiella ictaluri infection

Fish mucus acts as a physiological and immunological barrier for maintaining normal fish physiology and conferring defense against pathogens infection. Here we report proteomic profiling of skin mucus of yellow catfish before and after E. ictaluri infection by Label-free LC-MS/MS approach. A total of 918 non-redundant proteins were identified from 54443 spectra referring to yellow catfish genome database. Further annotation via GO and KEGG database revealed complex protein composition of yellow catfish mucus. Besides structural proteins in mucus, a lot of immune-related proteins were retrieved, such as lectins, complement components, antibacterial peptides and immunoglobins. 133 differentially-expressed proteins (DEPs), including 76 up-regulated and 57 down-regulated proteins, were identified, most of which were enriched into 17 pathways centering on "immune system" category with 33 proteins involved. Consistently, significant proliferation of mucus-secreting goblet cells and CYPA-expressing cells were observed along outside of yellow catfish skin after E. ictaluri infection, indicating an enhanced immune response to E. ictaluri infection in yellow catfish skin mucus. The proteomic data provide systematic protein information to comprehensively understand the biological function of yellow catfish skin mucus in response to bacterial infection.

Neuroprotective Effect of Phthalide Derivative CD21 against Ischemic Brain Injury:Involvement of MSR1 Mediated DAMP peroxiredoxin1 Clearance and TLR4 Signaling Inhibition

The macrophage scavenger receptor 1 (MSR1)-induced resolution of neuroinflammation may be a novel therapeutic strategy for ischemic stroke. Our previous study showed that the neuroprotective and anti-inflammatory effects of phthalide are associated with the inhibition of the post-ischemic damage-associated molecular pattern (DAMP)/Toll-like receptor 4 (TLR4) pathway. This study investigated the effects of the phthalide derivative CD21 on ischemic brain injury and the mechanism underlying MSR1-induced resolution of neuroinflammation. Using a rat model of 2 h transient middle cerebral artery occlusion (MCAO), MSR1-induced peroxiredoxin1 (PRX1) clearance in RAW264.7 macrophages were investigated. We show here that CD21 significantly ameliorated infarct volumes and neurological deficits in a dose-dependent manner with a ≥ 12 h therapeutic time window. Moreover, administration of 5 mg/kg/day CD21 over 24 h significantly reduced pathological damages, with associated inhibition of PRX1 expression, reduced TLR4/nuclear factor-κB activation and the suppression of the inflammatory response in MCAO rats. Furthermore, the expression of MAFB/MSR1 in the ischemic brain was elevated and the phagocytosis of PRX1 in CD68-positive macrophages isolated from the ischemic brain was enhanced. Further in vitro studies show that CD21 (20 μM) strongly enhanced the Msr1 mRNA and MSR1 protein levers in RAW264.7 cells and PRX1 internalization in cellular lysosomes, which were significantly reversed by N-acetylcysteine treatment. These results suggest that CD21 may exert neuroprotective and anti-inflammatory effects with a wide time window for the treatment of ischemic stroke. The anti-stroke effects of CD21 appear to be mediated partially via the induction of MSR1-promoted DAMP (PRX1) clearance, TLR4/nuclear factor-κB pathway inhibition, and the resolution of inflammation. Graphical Abstract The neuroprotective action of CD21 was associated with the resolution of neuroinflammation through enhancement of the MAFB-MSR1 pathway that leads to DAMP (PRX1) phagocytosis and TLR4 pathway inhibition. Red solid arrows represent promotion, red dotted arrow represents the positive correlation, green arrows represent inhibition.

Prdx1 Reduces Intracerebral Hemorrhage-Induced Brain Injury via Targeting Inflammation- and Apoptosis-Related mRNA Stability

RNA-binding proteins (RBPs) have been shown to be involved in posttranscriptional regulation, which plays an important role in the pathophysiology of intracerebral hemorrhage (ICH). Peroxiredoxin 1 (Prdx1), an RBP, plays an important role in regulating inflammation and apoptosis. On the basis that inflammation and apoptosis may contribute to ICH-induced brain injury, in this study, we used ICH models coupled with in vitro experiments, to investigate the role and mechanism of Prdx1 in regulating inflammation and apoptosis by acting as an RBP after ICH. We first found that Prdx1 was significantly up-regulated in response to ICH-induced brain injury and was mainly expressed in astrocytes and microglia in ICH rat brains. After overexpressing Prdx1 by injecting adeno-associated virus (AAV) into the striatum of rats at 3 weeks, we constructed ICH models and found that Prdx1 overexpression markedly reduced inflammation and apoptosis after ICH. Furthermore, RNA immunoprecipitation combined with high-throughput sequencing (RIP-seq) in vitro revealed that Prdx1 affects the stability of inflammation- and apoptosis-related mRNA, resulting in the inhibition of inflammation and apoptosis. Finally, overexpression of Prdx1 significantly alleviated the symptoms and mortality of rats subjected to ICH. Our results show that Prdx1 reduces ICH-induced brain injury by targeting inflammation- and apoptosis-related mRNA stability. Prdx1 may be an improved therapeutic target for alleviating the brain injury caused by ICH.