Copper-Binding Peptides Attenuate Microglia Inflammation through Suppression of NF-kB Pathway

Digestion of whey peptide induces antioxidant and anti-inflammatory bioactivity on glial cells: Sequences identification and structural activity analysis

Whey derived peptides have shown potential activity improving brain function in pathological condition. However, there is little information about their mechanism of action on glial cells, which have important immune functions in brain. Astrocytes and microglia are essential in inflammatory and oxidative defense that take place in neurodegenerative disease. In this work we evaluate antioxidant and anti-inflammatory potential bioactivity of whey peptide in glial cells. Peptides were formed during simulated gastrointestinal digestion (Infogest protocol), and low molecular weight (<5kDA) peptides (WPHf) attenuated reactive oxygen species (ROS) production induced by hydrogen peroxide stimulus in both cells in dose-dependent manner. WPHf induced an increase in the antioxidant glutathione (GSH) content and prevented GSH reduction induced by lipopolysaccharides (LPS) stimulus in astrocytes cells in a cell specific form. An increase in cytokine mRNA expression (TNFα and IL6) and nitric oxide secretion induced by LPS was attenuated by WPHf pre-treatment in both cells. The inflammatory pathway was dependent on NFκB activation. Bioactive peptide ranking analysis showed positive correlation with hydrophobicity and negative correlation with high molecular weights. The sequence identification revealed 19 peptides cross-referred with bioactive database. Whey peptides were rich in leucine, valine and tyrosine in the C-terminal region and lysine in the N-terminal region. The anti-inflammatory and antioxidant potential of whey peptides were assessed in glia cells and its mechanisms of action were related, such as modulation of antioxidant enzymes and anti-inflammatory pathways. Features of the peptide structure, such as molecular size, hydrophobicity and types of amino acids present in the terminal region are associated to bioactivity.

Copper exposure induces inflammation and PANoptosis through the TLR4/NF-κB signaling pathway, leading to testicular damage and impaired spermatogenesis in Wilson disease

Copper is a toxic heavy metal that causes various damage when it accumulates in the body beyond the physiological threshold. Wilson disease (WD) is an inherited disorder characterized by impaired copper metabolism. Reproductive damage in male patients with WD is gradually attracting attention. However, the underlying mechanisms of copper toxicity are unclear. In this study, we investigated the role of inflammation and PANoptosis in testicular damage and impaired spermatogenesis caused by copper deposition using the WD model toxic milk (TX) mice. Copper chelator-penicillamine and toll-like receptor 4 (TLR4) inhibitor-eritoran were used to intervene in TX mice in our animal experiment methods. Testis samples were collected from mice for further analysis. The results showed that the morphology and ultrastructure of the testis and epididymis in TX mice were damaged, and the sperm counts decreased significantly. The TLR4/nuclear factor kappa-B (NF-κB) signaling pathway was activated by copper deposition, which led to the upregulation of serum and testicular inflammatory factors in TX mice. Meanwhile, pyroptosis, apoptosis, and necroptosis were significant in the testis of TX mice. Both chelated copper or inhibited TLR4 expression markedly suppressed the TLR4/NF-κB signaling pathway, thereby reducing the expression of inflammatory factors. PANoptosis in the testis of TX mice was also reversed. Our study indicated that pathological copper exposure induces inflammation and PANoptosis through the TLR4/NF-κB signaling pathway, leading to toxic testicular damage and impaired spermatogenesis in WD.

mm9_circ_014683 regulates microglia polarization through canonical NFκB signaling pathway in diabetic retinopathy

Diabetic retinopathy (DR) is still the major cause of visual loss in working-aged people, one of the critical pathological processes are retinal microglia-mediated inflammation. Our previous study demonstrated that enhanced M1 microglial polarization was involved in retinal inflammation in DR, but the detailed mechanism needs further investigation. Circular RNAs (circRNAs) are important kind of noncoding RNAs involved in the regulation of various cell biological processes. Herein, the circRNA expression profiles of BV2 mouse microglia treated with or without glucose were detected, and a total of 347 differentially expressed circRNAs were identified in glucose-treated BV2 cells. The key circRNA mm9_circ_014683 increased after glucose stimulation. Inhibiting or overexpressing mm9_circ_014683 showed no effect on the proliferation and apoptosis of microglia. Inhibiting mm9_circ_014683 impeded M1 polarization and promoted M2 polarization, and overexpressing mm9_circ_014683 showed the opposite effect. A total of 216 differentially expressed genes were identified in mm9_circ_014683-knockdown BV2 cells, which were enriched in several signaling pathways, including the NFκB signaling pathway. Moreover, mm9_circ_014683 positively regulated the canonical, NFκB signaling pathway. Besides, mm9_circ_014683 was highly expressed in the retinal microglia of diabetic mice, and intraocular injection of Lv-circRNA inhibited M1 but enhanced M2 retinal microglial polarization. In conclusion, mm9_circ_014683 regulates microglial polarization through the canonical NFκB signaling pathway in diabetic retinopathy. This study may provide insight into the pathogenesis and treatment of DR.

The role and therapeutic potential of nuclear factor κB (NF-κB) in ischemic stroke

Stroke is a prevalent cerebrovascular condition with a global impact, causing significant rates of illness and death. Despite extensive research, the available treatment options for stroke remain restricted. Hence, it is crucial to gain a deeper understanding of the molecular mechanisms associated with the onset and advancement of stroke in order to establish a theoretical foundation for novel preventive and therapeutic approaches. NF-κB, also known as nuclear factor κB, is a transcription factor responsible for controlling the expression of numerous genes and plays a crucial role in diverse physiological processes. NF-κB is triggered and regulates neuroinflammation and other processes after stroke, promoting the generation of cytokine storms and contributing to the advancement of ischemic stroke (IS). Therefore, NF-κB could potentially play a vital role in stroke by regulating diverse pathophysiological processes. This review provides an overview of the functions of NF-κB in stroke and its governing mechanisms. In addition, our attention is directed towards various potential therapies that aim to inhibit the NF-κB signaling pathway in order to offer valuable insights for the advancement of innovative treatment approaches for stroke.

BAFF deficiency aggravated optic nerve crush-induced retinal ganglion cells damage by regulating apoptosis and neuroinflammation via NF-κB-IκBα signaling

Loss of retinal ganglion cells (RGCs) is a primary cause of visual impairment in glaucoma, the pathological process is closely related to neuroinflammation and apoptosis. B-cell activating factor (BAFF) is a fundamental survival factor mainly expressed in the B cell lineage. Evidence suggests its neuroprotective effect, but the expression and role in the retina have not yet been investigated. In this study, we adopt optic nerve crush (ONC) as an in vivo model and oxygen-glucose deprivation/reoxygenation (OGD/R) of RGCs as an in vitro model to investigate the expression and function of BAFF. We found that BAFF and its receptors were abundantly expressed in the retina and BAFF inhibition exacerbated the caspase 3-mediated RGCs apoptosis, glial cell activation and pro-inflammatory cytokines expression, which may be caused by the activation of the NF-κB pathway in vivo. In addition, we found that BAFF treatment could alleviate RGCs apoptosis, pro-inflammatory cytokines expression and NF-κB pathway activation, which could be reversed the effect by blockade of the NF-κB pathway in vitro. Meanwhile, we found that microglia induced to overexpress BAFF in the inflammatory microenvironment in a time-dependent manner. Taken together, our results indicated that BAFF deficiency promoted RGCs apoptosis and neuroinflammation through activation of NF-κB pathway in ONC retinas, suggesting that BAFF may serve as a promising therapeutic target for the treatment of glaucoma.

Bisphenol A exposure exacerbates tracheal inflammatory injury in selenium-deficient chickens by regulating the miR-155/TRAF3/ROS pathway

Bisphenol A (BPA) is an endocrine disruptor. Excessive BPA intake can damage the structure and function of the respiratory tract. Dietary selenium (Se) deficiency may also cause immune tissue damage. To investigate the potential mechanism of BPA on tracheal damage in selenium-deficient chickens and the role of microRNAs (miRNAs) in this process, we established in vitro and in vivo Se deficiency and BPA exposure models and screened out miR-155 for follow-up experiments. We further predicted and confirmed the targeting relationship between miR-155 and TRAF3 using TargetScan and dual luciferase assays and found that miR-155 was highly expressed and caused inflammatory damage. Further studies showed that BPA exposure increased airway oxidative stress, activated the NF-κB pathway, and caused inflammation and immune damage in selenium-deficient chickens, but down-regulating miR-155 and NAC treatment could reverse this phenomenon. This suggested that these pathways are regulated by the miR-155/TRAF3/ROS axis. In conclusion, BPA exposure aggravates airway inflammation in selenium-deficient chickens by regulating miR-155/TRAF3/ROS. This study revealed the mechanism of BPA exposure combined with Se deficiency in tracheal inflammatory injury in chickens and enriched the theoretical basis of BPA injury in poultry.

Copper neurotoxicity: Induction of cognitive dysfunction: A review

Cognitive dysfunction occurs mainly in certain diseases and in the pathological process of aging. In addition to this, it is also widespread in patients undergoing anesthesia, surgery, and cancer chemotherapy. Neuroinflammation, oxidative stress, mitochondrial dysfunction, impaired synaptic plasticity, and lack of neurotrophic support are involved in copper-induced cognitive dysfunction. In addition, recent studies have found that copper mediates cuproptosis and adversely affects cognitive function. Cuproptosis is a copper-dependent, lipoylated mitochondrial protein-driven, non-apoptotic mode of regulated cell death, which provides us with new avenues for identifying and treating related diseases. However, the exact mechanism by which cuproptosis induces cognitive decline is still unclear, and this has attracted the interest of many researchers. In this paper, we analyzed the pathological mechanisms and therapeutic targets of copper-associated cognitive decline, mainly in the context of neurodegenerative diseases, psychiatric and psychological disorders, and diabetes mellitus.

Time-course transcriptome analysis of lungs from mice infected with inhaled aerosolized Stenotrophomonas maltophilia

Background

Stenotrophomonas maltophilia (SMA) has emerged as an important pathogen capable of causing an opportunistic and nosocomial infection. We performed RNA sequencing (RNA-seq) of lung tissues from mice with pulmonary SMA infection over time via aerosolized intratracheal inhalation to investigate transcription profile changes in SMA-infected lungs.

Methods

A mouse model of acute lethal SMA pneumonia was established in this study using aerosolized intratracheal inhalation, laying the groundwork for future SMA research. RNA-seq was then used to create a transcriptional profile of the lungs of the model mice at 0, 4, 12, 24, 48, and 72 hours post-infection (hpi). Mfuzz time clustering, weighted gene coexpression network analysis (WGCNA), and Immune Cell Abundance Identifier for mouse (ImmuCellAI-mouse) were used to analyze RNA-seq data.

Results

A gradual change in the lung transcriptional profile was observed, which was consistent with the expected disease progression. At 4 hpi, the expression of genes related to the acute phase inflammatory response increased, as predicted abundance of innate immune cells. At this stage, an increased demand for energy was also observed, including an increase in the expression of genes involved in circulation, muscle function and mitochondrial respiratory chain function. The expression of genes associated with endoplasmic reticulum stress (ERS) and autophagy increased at 24 hpi. Unlike the number of natural killer (NK) cells following most bacterial lung infections, the abundance of NK cells decreased following infection with SMA. The expression levels of Cxcl10, Cd14, Gbp5, Cxcr2, Tnip1, Zc3h12a, Egr1, Sell and Gbp2 were high and previously unreported in SMA pneumonia, and they may be important targets for future studies.

Conclusions

To our knowledge, this is the first study to investigate the pulmonary transcriptional response to SMA infection. The findings shed light on the molecular mechanisms underlying the pathogenesis of SMA pneumonia, which may aid in the development of therapies to reduce the occurrence of SMA pulmonary infection.

Identification and validation of potential diagnostic signature and immune cell infiltration for NAFLD based on cuproptosis-related genes by bioinformatics analysis and machine learning

Background and aims

Cuproptosis has been identified as a key player in the development of several diseases. In this study, we investigate the potential role of cuproptosis-related genes in the pathogenesis of nonalcoholic fatty liver disease (NAFLD).

Method

The gene expression profiles of NAFLD were obtained from the Gene Expression Omnibus database. Differential expression of cuproptosis-related genes (CRGs) were determined between NAFLD and normal tissues. Protein-protein interaction, correlation, and function enrichment analyses were performed. Machine learning was used to identify hub genes. Immune infiltration was analyzed in both NAFLD patients and controls. Quantitative real-time PCR was employed to validate the expression of hub genes.

Results

Four datasets containing 115 NAFLD and 106 control samples were included for bioinformatics analysis. Three hub CRGs (NFE2L2, DLD, and POLD1) were identified through the intersection of three machine learning algorithms. The receiver operating characteristic curve was plotted based on these three marker genes, and the area under the curve (AUC) value was 0.704. In the external GSE135251 dataset, the AUC value of the three key genes was as high as 0.970. Further nomogram, decision curve, calibration curve analyses also confirmed the diagnostic predictive efficacy. Gene set enrichment analysis and gene set variation analysis showed these three marker genes involved in multiple pathways that are related to the progression of NAFLD. CIBERSORT and single-sample gene set enrichment analysis indicated that their expression levels in macrophages, mast cells, NK cells, Treg cells, resting dendritic cells, and tumor-infiltrating lymphocytes were higher in NAFLD compared with control liver samples. The ceRNA network demonstrated a complex regulatory relationship between the three hub genes. The mRNA level of these hub genes were further confirmed in a mouse NAFLD liver samples.

Conclusion

Our study comprehensively demonstrated the relationship between NAFLD and cuproptosis, developed a promising diagnostic model, and provided potential targets for NAFLD treatment and new insights for exploring the mechanism for NAFLD.

Global status and research trends of cuprotosis research: A bibliometrics study via CiteSpace

Cuproptosis, a novel copper ion-dependent cell death type being regulated in cells, has raised concerns but lacks scientific analysis. Therefore, this study aimed to analyze the global status and emerging trends in cuprotosis research using bibliometric methods. Publications related to cuprotosis were systematically retrieved from the Web of Science Core Collection and then screened according to the inclusion criteria. Next, CiteSpace and Microsoft Excel 2021 were used to measure and visualize annual publications, categories, journals, countries, institutions, authors, co-cited references, and keywords to identify future global status and trends. A total of 2776 publications on cuprotosis were included, and the overall trend in the number of publications exhibited a rapid increase over the years. Biochemistry and Molecular Biology is the most common category, whereas the Journal of Inorganic Biochemistry is the most active. The United States is the country that produces the most articles, and University of Melbourne in Australia is the core institution involved in this field. Furthermore, Chan Pak of Stanford University is the most prolific author. Oxidative stress and antioxidant, the toxicity of copper in vitro, anticancer mechanism, and brain injury in neurological diseases are hot topics. The research frontiers are copper complexes, anticancer activity, DeoxyriboNucleic Acid binding, inflammation, and nanoparticles. This study provides the current status and trends in cuprotosis research. It may help researchers to identify hot topics and get ideas for future research directions in this field, focusing on copper complexes, anticancer activity, DeoxyriboNucleic Acid binding, inflammation, and nanoparticles.

Inhibition of inflammatory microglia by dietary fiber and short-chain fatty acids

Microglia play a vital role maintaining brain homeostasis but can also cause persistent neuroinflammation. Short-chain fatty acids (SCFAs) produced by the intestinal microbiota have been suggested to regulate microglia inflammation indirectly by signaling through the gut-brain axis or directly by reaching the brain. The present work evaluated the anti-inflammatory effects of SCFAs on lipopolysaccharide (LPS)-stimulated microglia from mice fed inulin, a soluble fiber that is fermented by intestinal microbiota to produce SCFAs in vivo, and SCFAs applied to primary microglia in vitro. Feeding mice inulin increased SCFAs in the cecum and in plasma collected from the hepatic portal vein. Microglia isolated from mice fed inulin and stimulated with LPS in vitro secreted less tumor necrosis factor α (TNF-α) compared to microglia from mice not given inulin. Additionally, when mice were fed inulin and injected i.p with LPS, the ex vivo secretion of TNF-α by isolated microglia was lower than that secreted by microglia from mice not fed inulin and injected with LPS. Similarly, in vitro treatment of primary microglia with acetate and butyrate either alone or in combination downregulated microglia cytokine production with the effects being additive. SCFAs reduced histone deacetylase activity and nuclear factor-κB nuclear translocation after LPS treatment in vitro. Whereas microglia expression of SCFA receptors Ffar2 or Ffar3 was not detected by single-cell RNA sequencing analysis, the SCFA transporters Mct1 and Mct4 were. Nevertheless, inhibiting monocarboxylate transporters on primary microglia did not interfere with the anti-inflammatory effects of SCFAs, suggesting that if SCFAs produced in the gut regulate microglia directly it is likely through an epigenetic mechanism following diffusion.

The metal ion hypothesis of Alzheimer's disease and the anti-neuroinflammatory effect of metal chelators

Alzheimer's disease (AD), characterized by the β-amyloid protein (Aβ) deposition and tau hyperphosphorylation, is the most common dementia with uncertain etiology. The clinical trials of Aβ monoclonal antibody drugs have almost failed, giving rise to great attention on the other etiologic hypothesis regarding AD such as metal ions dysmetabolism and chronic neuroinflammation. Mounting evidence revealed that the metal ions (iron, copper, and zinc) were dysregulated in the susceptible brain regions of AD patients, which was highly associated with Aβ deposition, tau hyperphosphorylation, neuronal loss, as well as neuroinflammation. Further studies uncovered that iron, copper and zinc could not only enhance the production of Aβ but also directly bind to Aβ and tau to promote their aggregations. In addition, the accumulation of iron and copper could respectively promote ferroptosis and cuproptosis. Therefore, the metal ion chelators were recognized as promising agents for treating AD. This review comprehensively summarized the effects of metal ions on the Aβ dynamics and tau phosphorylation in the progression of AD. Furthermore, taking chronic neuroinflammation contributes to the progression of AD, we also provided a summary of the mechanisms concerning metal ions on neuroinflammation and highlighted the metal ion chelators may be potential agents to alleviate neuroinflammation under the condition of AD. Nevertheless, more investigations regarding metal ions on neuroinflammation should be taken into practice, and the effects of metal ion chelators on neuroinflammation should gain more attention. Running title: Metal chelators against neuroinflammation.

Hemp Protein Hydrolysates Modulate Inflammasome-Related Genes in Microglial Cells

A prolonged inflammatory response can lead to the development of neurodegenerative diseases such as Alzheimer's disease. Enzymatic hydrolysis is a sustainable way to increase the value of protein sources by obtaining peptides that can exert bioactivity. Hemp (Cannabis sativa L.) protein hydrolysates have been proven to exert anti-inflammatory activity. In this study, two hemp protein hydrolysate (HPHs), obtained with Alcalase as sole catalyst, or with Alcalase followed by Flavourzyme, were evaluated as inflammatory mediators (TNFα, IL-1β, IL-6, and IL-10), microglial polarization markers (Ccr7, iNos, Arg1, and Ym1), and genes related to inflammasome activation (Nlrp3, Asc, Casp1, and Il18), employing the lipopolysaccharide (LPS)-induced neuroinflammation model in murine BV-2 microglial cells. A significant decrease of the expression of proinflammatory genes (e.g., Tnfα, Ccr7, inos, and Nlrp3, among others) and increase of the expression anti-inflammatory cytokines in microglial cells was observed after treatment with the test HPHs. This result in the cell model suggests a polarization toward an anti-inflammatory M2 phenotype. Our results show that the evaluated HPHs show potential neuroprotective activity in microglial cells via the inflammasome.

Microglial Dysfunction in Neurodegenerative Diseases via RIPK1 and ROS

Microglial dysfunction is a major contributor to the pathogenesis of multiple neurodegenerative diseases. The neurotoxicity of microglia associated with oxidative stress largely depends on NF-κB pathway activation, which promotes the production and release of microglial proinflammatory cytokines and chemokines. In this review, we discuss the current literature on the essential role of the NF-κB pathway on microglial activation that exacerbates neurodegeneration, with a particular focus on RIPK1 kinase activity-dependent microglial dysfunction. As upregulated RIPK1 kinase activity is associated with reactive oxygen species (ROS) accumulation in neurodegenerative diseases, we also discuss the current knowledge about the mechanistic links between RIPK1 activation and ROS generation. Given RIPK1 kinase activity and oxidative stress are closely regulated with each other in a vicious cycle, future studies are required to be conducted to fully understand how RIPK1 and ROS collude together to disturb microglial homeostasis that drives neurodegenerative pathogenesis.

Comprehensive analysis of cuproptosis-related genes in immune infiltration and diagnosis in ulcerative colitis

Objectives

Cuproptosis is a recently discovered form of programmed cell death; however, its role in ulcerative colitis (UC) remains a void.

Methods

Three gene expression profiles were acquired from the GEO database. Subsequently, the single sample gene set enrichment analysis (ssGSEA) was performed to identify the immune infiltration characteristics of UC. Correlation analysis between cuproptosis and immune infiltration was further conducted, and the cuproptosis-related genes were applied to construct a UC diagnostic model. Subsequently, analysis results of microarray data were experimentally validated by DSS-induced colitis in mice. Finally, therapeutic agents for the cuproptosis-related genes were screened owing to the gaping field of therapeutic agents on cuproptosis.

Results

Three gene expression profiles with 343 samples (290 UC and 53 healthy samples) were included. Immune infiltration revealed that UC patients had a higher level of DCs, B cells, CD8⁺ T cells, iDCs, Macrophages, neutrophils, pDCs, T helper cells, Tfh, Th1 cells, Th2 cells, TIL and Treg than normal subjects. Moreover, almost all cuproptosis-related genes were significantly negatively associated with immune infiltration in UC patients. The risk prediction model based on cuproptosis-related genes showed an excellent discrimination for UC. Animal experiments revealed significant alterations in genes essential for cuproptosis between DSS-induced colitis mice and healthy controls, providing experimental validation for the analysis results of microarray data. Further analysis revealed that latamoxef, vitinoin, clomipramine, chlorzoxazone, glibenclamide, pyruvic acid, clindamycin, medrysone, caspan, and flavin adenine dinucleotide might be the target agents for cuproptosis-related genes.

Conclusions

In conclusion, cuproptosis was significantly associated with immune infiltration in UC, and the cuproptosis-related genes showed an excellent discrimination for UC.

TanP: A Multifunctional Anionic Peptide From Tityus stigmurus Scorpion Venom

Anionic peptides of scorpions are molecules rich in aspartic and/or glutamic acid residues and correspond to a class of peptides without disulfide bonds that are still little explored. TanP is a linear anionic peptide (50 amino acid residues and net charge -20) present in the venom gland of the scorpion, Tityus stigmurus, with chelating properties for Cu2+ ion and immunomodulatory properties. The therapeutic application of chelating molecules is related to cases of acute or chronic intoxication by metals, neurodegenerative diseases, hematological diseases, healing of skin wounds, cardiovascular diseases, and cancer. In this approach, the chelating activity of TanP was evaluated in relation to new metal ions (Fe2+ and Zn2+) of biological importance, as well as its antioxidant, hemostatic, immunomodulatory, and healing potential, aiming to expand the biological and biotechnological potential of this peptide. TanP (25 µM) was able to form stable complexes with Fe2+ in a ratio of 1:5 (TanP: Fe2+). Theoretical results suggest that TanP can work as a sensor to identify and quantify Fe2+ ions. The fluorescence intensity of TanP (1.12 µM) decreased significantly after the addition of Fe2+, obtaining the highest ratio 1: 7.4 (TanP: Fe2+) that led to the lowest fluorescence intensity. For Zn2+, no relevant spectral change was noted. TanP (50 µM) showed a maximum of 3% of hemolytic activity, demonstrating biocompatibility, as well as exhibiting a 1,1-diphenyl-2-picrylhydrazyl radical-scavenging activity of above 70% at all the concentrations tested (1-25 μM), and 89.7% iron-chelating activity at 25 μM and 96% hydroxyl radical-scavenging activity at 73.6 μM. In addition, TanP (12.5 and 25 µM) revealed an anticoagulant effect, prolonging the clotting time in prothrombin time and activated partial thromboplastin time assays, with no fibrinogenolytic activity. TanP (12.5 and 25 µM) induced the release of TNF-α by murine macrophages, in the absence of lipopolysaccharides, with a concentration-dependent increase and also stimulated the migration of 3T3 cells in the in vitro healing assay. Thus, TanP revealed a multifunctional potential, being useful as a prototype for the development of new therapeutic and biotechnological agents.