Myeloperoxidase and Neurological Disorder: A Crosstalk

Enzyme-responsive, multi-lock optical probes for molecular imaging and disease theranostics

Optical imaging is an indispensable tool for non-invasive visualization of biomolecules in living organisms, thereby offering a sensitive approach for disease diagnosis and image-guided disease treatment. Single-lock activatable optical probes (SOPs) that specifically switch on optical signals in the presence of biomarkers-of-interest have shown both higher detection sensitivity and imaging quality as compared to conventional "always-on" optical probes. However, such SOPs can still show "false-positive" results in disease diagnosis due to non-specific biomarker expression in healthy tissues. By contrast, multi-lock activatable optical probes (MOPs) that simultaneously detect multiple biomarkers-of-interest could improve detection specificity towards certain biomolecular events or pathological conditions. In this Review, we discuss the recent advancements of enzyme-responsive MOPs, with a focus on their biomedical applications. The higher detection specificity of MOPs could in turn enhance disease diagnosis accuracy and improve treatment efficacy in image-guided disease therapy with minimal toxicity in the surrounding healthy tissues. Finally, we discuss the current challenges and suggest future applications of MOPs.

Building an Understanding of Proteostasis in Reproductive Cells: The Impact of Reactive Carbonyl Species on Protein Fate

Significance: Stringent regulation of protein homeostasis pathways, under both physiological and pathological conditions, is necessary for the maintenance of proteome fidelity and optimal cell functioning. However, when challenged by endogenous or exogenous stressors, these proteostasis pathways can become dysregulated with detrimental consequences for protein fate, cell survival, and overall organism health. Most notably, there are numerous somatic pathologies associated with a loss of proteostatic regulation, including neurodegenerative disorders, type 2 diabetes, and some cancers. Recent Advances: Lipid oxidation-derived reactive carbonyl species (RCS), such as 4-hydroxynonenal (4HNE) and malondialdehyde, are relatively underappreciated purveyors of proteostatic dysregulation, which elicit their effects via the nonenzymatic post-translational modification of proteins. Emerging evidence suggests that a subset of germline proteins can serve as substrates for 4HNE modification. Among these, prevalent targets include succinate dehydrogenase, heat shock protein A2 and A-kinase anchor protein 4, all of which are intrinsically associated with fertility. Critical Issues: Despite growing knowledge in this field, the RCS adductomes of spermatozoa and oocytes are yet to be comprehensively investigated. Furthermore, the manner by which RCS-mediated adduction impacts protein fate and drives cellular responses, such as protein aggregation, requires further examination in the germline. Given that RCS-protein adduction has been attributed a role in infertility, there has been sparked research investment into strategies to prevent lipid peroxidation in germ cells. Future Directions: An increased depth of knowledge regarding the mechanisms and substrates of RCS-mediated protein modification in reproductive cells may reveal important targets for the development of novel therapies to improve fertility and pregnancy outcomes for future generations.

Ratiometric Fluorescent Probe for Super-Resolution Imaging of Lysosome HClO in Ferroptosis Cells

Ferroptosis is an iron-dependent programmed cell death that is characterized by the dysregulation of lipid reactive oxygen species (ROS) production, causing abnormal changes in hypochlorous acid (HClO) levels in lysosomes. Super-resolution imaging can observe the fine structure of the lysosome at the nanometer level; therefore, it can be used to detect lysosome HClO levels during ferroptosis at the suborganelle level. Herein, we utilize a ratiometric fluorescent probe, SRF-HClO, for super-resolution imaging of lysosome HClO. Structured-illumination microscopy (SIM) improves the accuracy of lysosome targeting and enables the probe SRF-HClO to be successfully applied to rapidly monitor the up-regulated lysosome HClO at the nanoscale during inflammation and ferroptosis. Importantly, the probe SRF-HClO can also detect HClO changes in inflammatory and ferroptosis mice and evaluate the inhibitory effect of ferroptosis on mice tumors.

Basic Science of Neuroinflammation and Involvement of the Inflammatory Response in Disorders of the Nervous System

Neuroinflammation is a key immune response observed in many neurologic diseases. Although an appropriate immune response can be beneficial, aberrant activation of this response recruits excessive proinflammatory cells to cause damage. Because the central nervous system is separated from the periphery by the blood-brain barrier (BBB) that creates an immune-privileged site, it has its own unique immune cells and immune response. Moreover, neuroinflammation can compromise the BBB causing an influx of peripheral immune cells and factors. Recent advances have brought a deeper understanding of neuroinflammation that can be leveraged to develop more potent therapies and improve patient selection.

Physalin H ameliorates LPS-induced acute lung injury via KEAP1/NRF2 axis

Physalin H (PH), a withanolide isolated from Physalisangulata L. has been reported to have anti-inflammatory effect. However, its impact on acute lung injury (ALI) remains unexplored. In this study, we observed that PH significantly alleviated inflammation in LPS-stimulated macrophages by suppressing the release of proinflammatory cytokines (TNF-α, IL-1β, and IL-6) and down-regulating the expression of the inflammation-related genes. RNA sequencing analysis revealed a significant up-regulation of the NRF2 pathway by PH. Further investigation elucidated that PH attenuated the ubiquitination of NRF2 by impeding the interaction between NRF2 and KEAP1, thereby facilitating NRF2 nuclear translocation and up-regulating the expression of target genes. Consequently, it regulated redox system and exerted anti-inflammatory effect. Consistently, PH also significantly alleviated pathological damage and inflammation in LPS-induced ALI mice model, which could be reversed by administration of an NRF2 inhibitor. Collectively, these results suggest that PH ameliorates ALI by activating the KEAP1/NRF2 pathway. These findings provide a foundation for further development of pH as a new anti-inflammatory agent for ALI therapy.

Targeting myeloperoxidase to stabilize unruptured aneurysm: an imaging-guided approach

Inflammation plays a key role in pathogenesis and rupture of aneurysms. Non-invasively and dynamically monitoring aneurysm inflammation is critical. This study evaluated myeloperoxidase (MPO) as an imaging biomarker and therapeutic target for aneurysm inflammation using an elastase-induced rabbit model treated with or without 4-aminobenzoic acid hydrazide (ABAH), an irreversible inhibitor of MPO. Myeloperoxidase-sensitive magnetic resonance imaging (MRI) using Mn-TyrEDTA, a peroxidase activity-dependent contrast agent, revealed weak contrast enhancement in contralateral arteries and decreased contrast enhancement in aneurysm walls with ABAH treatment, indicating MPO activity decreased and inflammation mitigated. This was supported by reduced immune cell infiltration, matrix metalloproteinases (MMP-2 and - 9) activity, ROS production and arterial wall destruction on histology. Finally, the aneurysm expansion rate remained < 50% throughout the study in the ABAH(+) group, but increased gradually in the ABAH(-) group. Our results suggest that inhibition of MPO attenuated inflammation and expansion of experimental aneurysm and MPO-sensitive MRI showed promise as a noninvasive tool for monitoring aneurysm inflammation.

Pharmacological Activities, Therapeutic Effects, and Mechanistic Actions of Trigonelline

Trigonelline (TRG) is a natural polar hydrophilic alkaloid that is found in many plants such as green coffee beans and fenugreek seeds. TRG potentially acts on multiple molecular targets, including nuclear factor erythroid 2-related factor 2 (Nrf2), peroxisome proliferator-activated receptor γ, glycogen synthase kinase, tyrosinase, nerve growth factor, estrogen receptor, amyloid-β peptide, and several neurotransmitter receptors. In this review, we systematically summarize the pharmacological activities, medicinal properties, and mechanistic actions of TRG as a potential therapeutic agent. Mechanistically, TRG can facilitate the maintenance and restoration of the metabolic homeostasis of glucose and lipids. It can counteract inflammatory constituents at multiple levels by hampering pro-inflammatory factor release, alleviating inflammatory propagation, and attenuating tissue injury. It concurrently modulates oxidative stress by the blockage of the detrimental Nrf2 pathway when autophagy is impaired. Therefore, it exerts diverse therapeutic effects on a variety of pathological conditions associated with chronic metabolic diseases and age-related disorders. It shows multidimensional effects, including neuroprotection from neurodegenerative disorders and diabetic peripheral neuropathy, neuromodulation, mitigation of cardiovascular disorders, skin diseases, diabetic mellitus, liver and kidney injuries, and anti-pathogen and anti-tumor activities. Further validations are required to define its specific targeting molecules, dissect the underlying mechanistic networks, and corroborate its efficacy in clinical trials.

A Photoelectrochemical Sensor for the Detection of Hypochlorous Acid with a Phenothiazine-Based Photosensitizer

This paper presents the development of a photoelectrochemical sensor for hypochlorous acid (HOCl) detection, employing a phenothiazine-based organic photosensitizer (Dye-PZ). The designed probe, Dye-PZ, follows a D-π-A structure with phenothiazine as the electron-donating group and a cyano-substituted pyridine unit as the electron-accepting group. A specific reaction of the phenothiazine sulfur atom with HOCl enables selective recognition. The covalent immobilization of Dye-PZ onto a titanium dioxide nanorod-coated fluorine-doped tin oxide electrode (FTO/TiO2) using bromo-silane coupling agent (BrPTMS) resulted in the fabrication of the photoanode FTO/TiO2/BrPTMS/Dye-PZ. The photoanode exhibited a significant photoresponse under visible-light irradiation, with a subsequent reduction in photocurrent upon reaction with HOCl. The oxidation of the phenothiazine sulfur atom to a sulfoxide diminished the internal charge transfer (ICT) effect. Leveraging this principle, the successful photoelectrochemical sensing of HOCl was achieved. The sensor showed high stability, excellent reproducibility, and selective sensitivity for HOCl detection. Our study provides a novel approach for the development of efficient photoelectrochemical sensors based on organic photosensitizers, with promising applications in water quality monitoring and biosensing.

A turn-on fluorescence strategy for hypochlorous acid detection based on DNAzyme-assisted cyclic signal amplification

Hypochlorous acid (HClO) is a crucial active oxygen component and one of the innate immunity's barrier substances in the body. Abnormal fluctuations in HClO concentration can lead to increased oxidative stress, cellular dysfunction, and the onset of various diseases. Thus, developing convenient, affordable, efficient, and sensitive methods to monitor HClO concentration in healthcare and pathophysiology research is highly significant. In this study, we developed a novel fluorescence strategy for HClO detection based on nucleic acid oxidative cleavage and Pb2+-dependent DNAzyme. By introducing a phosphorothioate site in the hairpin-structured nucleic acid sequence, the nucleic acid probe specifically recognized HClO and underwent oxidative cleavage. Upon cleavage, the enzyme strand is liberated, forming DNAzyme. This DNAzyme then cleaves the substrate strand, liberating the initially quenched fluorescent dyes and generating a turn-on fluorescent signal. The enzyme strand produced by the oxidative cleavage of HClO can be repeatedly utilized, thus realizing the cyclic signal amplification to reduce background noise. We verified the detection mechanism of this strategy through stepwise fluorescence spectroscopy analysis and electrophoresis. Under optimal experimental conditions, the method achieved a detection limit of 5.38 nM and a linear range of 1 nM-800 nM. This method demonstrated exceptional performance in actual biological sample testing and presented an exciting opportunity for expanded utilization in clinical diagnosis and medical research.

Developing a Two-Photon "AND" Logic Probe and Its Application in Alzheimer's Disease Differentiation

In Alzheimer's disease, hypochlorous acid involved in the clearance of invading bacteria or pathogens and butyrylcholinesterase engaged in the hydrolysis of the neurotransmitter acetylcholine are relatively significantly altered. However, there are few dual detection probes for hypochlorous acid and butyrylcholinesterase. In addition, single-response probes suffer from serious off-target effects and near-infrared probes do not easily penetrate the blood-brain barrier due to their excessive molecular weight. In this work, we constructed a two-photon fluorescent probe that recognizes hypochlorous acid and butyrylcholinesterase based on a dual-lock strategy. The thiocarbonyl group is oxidized in the presence of hypochlorous acid, and the hydrolysis occurs at the 7-position ester bond in the existence of butyrylcholinesterase, releasing a strongly fluorescent fluorophore, 4-methylumbelliferone. Excellent imaging was performed in PC12 cells using this probe, and deep two-photon imaging was observed in the brains of AD mice after tail vein injection with this probe. It indicates that the probe can provide a promising tool for the more precise diagnosis of Alzheimer's disease.

The relationship between oxidative stress and psychotic disorders in 22q11.2 deletion syndrome

BACKGROUND

22q11.2 Deletion syndrome (22q11.2DS) is the most common microdeletion syndrome in humans. This condition is associated with a wide range of symptoms including immune and neuropsychiatric disorders. Notably, psychotic disorders including schizophrenia have a prevalence of ∼ 30%. A growing body of evidence indicates that neuroinflammation and oxidative stress (OS) play a role in the pathophysiology of schizophrenia. In this study, we aim to assess the interaction between 22q11.2DS, OS and schizophrenia.

METHODS

Blood samples were collected from 125 participants (including individuals with 22q11.2DS [n = 73] and healthy controls [n = 52]) from two sites: Sheba Medical Center in Israel, and University Hospital Gasthuisberg in Belgium. Baseline OS levels were evaluated by measuring Myeloperoxidase (MPO) activity. A sub-sample of the Israeli sample (n = 50) was further analyzed to examine survival of Peripheral Blood Mononuclear Cells (PBMCs) following induction of OS using vitamin K3.

RESULTS

The levels of MPO were significantly higher in all individuals with 22q11.2DS, compared to healthy controls (0.346 ± 0.256 vs. 0.252 ± 0.238, p =.004). In addition, when comparing to healthy controls, the PBMCs of individuals with 22q11.2DS were less resilient to induced OS, specifically the group diagnosed with psychotic disorder (0.233 ± 0.206 for the 22q11.2DS individuals with psychotic disorders, 0.678 ± 1.162 for the 22q11.2DS individuals without psychotic disorders, and 1.428 ± 1.359 for the healthy controls, p =.003, η2 = 0.207).

CONCLUSIONS

Our results suggest that dysregulation of OS mechanisms may play a role in the pathophysiology of the 22q11.2DS phenotype. The 22q11.2DS individuals with psychotic disorders were more sensitive to induction of OS, but did not present significantly different levels of OS at baseline. These results may be due to the effect of antipsychotic treatment administered to this sup-group. By elucidating novel molecular pathways, early identification of biochemical risk markers for 22q11.2DS and psychotic disorders can be detected. This can ultimately pave the way to the design of early and more precise interventions of individuals with 22q11.2DS.

A New and Fast-Response Fluorescent Probe for Monitoring Hypochlorous Acid Derived from Myeloperoxidase

Hypochlorous acid (HOCl) has been implicated in numerous pathologies associated with an inflammatory component, but its selective and sensitive detection in biological settings remains a challenge. In this report, imaging of HOCl was realized with a thiomorpholine-based probe as derivative of nitrobenzothiadiazole (NBD-S-TM). The fluorescence is based on photoinduced electron transfer by using nitrobenzothiadiazole core as a donor and thiomorpholine substituent as an acceptor. NBD-S-TM showed high sensitivity and a fast response to HOCl k = (2.6 ± 0.2) × 107 M-1s-1 with a 1:1 stoichiometry. The detection limit for HOCl was determined to be 60 nM. Furthermore, the desirable features of NBD-S-TM for the detection of HOCl in aqueous solutions, such as its reliability at physiological pH, rapid fluorescence response, and biocompatibility, enabled its application in the detection of HOCl in myeloperoxidase enzymatic system. Moreover, NBD-S-TM exhibited excellent selectivity and sensitivity for HOCl over other biologically relevant species, such as hydrogen peroxide and peroxynitrite. The fluorescent S-oxidized product (NBD-S-TSO) is only formed in the presence of HOCl. Probing with NBD-S-TM may be helpful to further the development of high throughput screening assays to monitor the activity of myeloperoxidase.

Epirubicin Treatment Induces Neurobehavioral, Oxido-Inflammatory and Neurohistology Alterations in Rats: Protective Effect of the Endogenous Metabolite of Tryptophan - 3-Indolepropionic Acid

Epirubicin's (EPI) efficacy as a chemotherapeutic agent against breast cancer is limited by EPI's neurotoxicity associated with increased oxidative and inflammatory stressors. 3-Indolepropionic acid (3-IPA) derived from in vivo metabolism of tryptophan is reported to possess antioxidative properties devoid of pro-oxidant activity. In this regard, we investigated the effect of 3-IPA on EPI-mediated neurotoxicity in forty female rats (180-200 g; five cohorts (n = 6) treated as follows: Untreated control; EPI alone (2.5 mg/Kg); 3-IPA alone (40 mg/Kg body weight); EPI (2.5 mg/Kg) + 3-IPA (20 mg/Kg) and EPI (2.5 mg/Kg) + 3-IPA (40 mg/Kg) for 28 days. Experimental rats were treated with EPI via intraperitoneal injection thrice weekly or co-treated with 3-IPA daily by gavage. Subsequently, the rat's locomotor activities were measured as endpoints of neurobehavioural status. After sacrifice, inflammation, oxidative stress and DNA damage biomarkers were assessed in rats' cerebrum and cerebellum alongside histopathology. Our results demonstrated that locomotor and exploratory deficits were pronounced in EPI-alone treated rats and improved in the presence of 3-IPA co-treatment. EPI-mediated decreases in tissue antioxidant status, increases in reactive oxygen and nitrogen species (RONS), as well as in lipid peroxidation (LPO) and xanthine oxidase (XO) were lessened in the cerebrum and cerebellum of 3-IPA co-treated rats. Increases in nitric oxide (NO) and 8-hydroxydeguanosin (8-OHdG) levels and myeloperoxidase MPO activity were also abated by 3-IPA. Light microscopic examination of the cerebrum and cerebellum revealed EPI-precipitated histopathological lesions were subsequently alleviated in rats co-treated with 3-IPA. Our findings demonstrate that supplementing endogenously derived 3-IPA from tryptophan metabolism enhances tissue antioxidant status, protects against EPI-mediated neuronal toxicity, and improves neurobehavioural and cognitive levels in experimental rats. These findings may benefit breast cancer patients undergoing Epirubicin chemotherapy.

The neuroprotective and antidiabetic effects of trigonelline: A review of signaling pathways and molecular mechanisms

The global epidemic of diabetes has brought heavy pressure on public health. New effective anti-diabetes strategies are urgently needed. Trigonelline is the main component of fenugreek, which has been proved to have a good therapeutic effect on diabetes and diabetic complications. Trigonelline achieves amelioration of diabetes, the mechanisms of which include the modulation of insulin secretion, a reduction in oxidative stress, and the improvement of glucose tolerance and insulin resistance. Besides, trigonelline has been reported to be a neuroprotective agent against many neurologic diseases including Alzheimer's disease, Parkinson's disease, stroke, and depression. Concerning the potential therapeutic effects of trigonelline, comprehensive clinical trials are warranted to evaluate this valuable molecule.

Design, synthesis, and biological activity studies on benzimidazole derivatives targeting myeloperoxidase

Myeloperoxidase (MPO) plays a key role in human antimicrobial system by oxidizing vital molecules of microorganisms in phagolysosomes through produced hypochlorous acid (HOCl). However, MPO can be released outside the phagocyte and produces reactive intermediates leading to tissue damage. MPO, as a local mediator of tissue damage, has been associated with inflammatory diseases such as renal injury, multiple sclerosis, cardiovascular and neurodegenerative diseases. Therefore, the enzyme currently draws attention as a potential therapeutic target. In this study, isomeric 1,3-dihydro-2H-benzo[d]imidazole-2-thione derivatives having amide, hydrazide and hydroxamic acid groups either on nitrogen or on sulphur atom were designed and their inhibitory activity was determined on chlorination and peroxidation cycles of MPO. Among the compounds, 2-(2-thioxo-2,3-dihydro-1H-benzo[d]imidazole-1-yl)acetohydrazide(C19) was found as the most active inhibitor on both cycles.

Adropin and MOTS-c as new peptides: Do levels change in neurodegenerative diseases and ischemic stroke?

BACKGROUND

Neurological diseases such as Alzheimer's disease and Parkinson's disease (AD, PD), acute ischemic stroke (AIS), and multiple sclerosis (MS) are thought to be deeply affected by changes in the pathophysiological processes of neurons. As new peptides, it was aimed to evaluate the level of adropin and MOTS-c (mitochondrial open reading frame of the 12S rRNA-c) and its possible relationship with NSE (neuron-specific enolase) and NF-L (neurofilament light chain) in terms of neuronal interaction.

METHODS

This study was conducted with 32 patients from each subgroup and group-appropriate controls. Disease identifiers and hemogram/biochemical parameters specific to the groups of participants were obtained. Additionally, plasma adropin, MOTS-c, NSE, and NF-L levels were evaluated by the ELISA method.

RESULTS

Plasma adropin levels were decreased in the AD group and decreased in MOTS-c, AIS, and AD groups compared to the control (p < 0.05). Similar values were found in the MS group compared to its control (p > 0.05). In correlation analysis of these markers with laboratory parameters, while platelet and cholesterol levels were negatively correlated with adropin levels; platelet, lymphocyte, and triglyceride levels were positively correlated with MOTS-c (p < 0.05).

CONCLUSION

This study provides new information about adropin may be potentially important markers in AD and MOTS-C in AIS and AD. Future studies are needed to examine the relationship between changes in metabolic profiles and these peptides.

Fluorescent phenothiazine-fused boron complexes for ratiometric hypochlorite imaging

Fluorescent hypochlorite probes with ratiometric imaging ability are highly desirable for imaging hypochlorite in biological systems. However, it is still challenging to develop new scaffolds for these probes. In this study, we demonstrate that phenothiazine-fused boron complexes are promising scaffolds for the design of ratiometric fluorescent hypochlorite probes. The synthesized complexes based on the scaffold show ultrafast and ratiometric absorption/fluorescence changes for hypochlorite. We also developed an endoplasmic reticulum-targeting probe and demonstrated that it has excellent real-time imaging ability for both endogenous and exogenous hypochlorite in the endoplasmic reticulum of living cells.

Tailoring Materials for Epilepsy Imaging: From Biomarkers to Imaging Probes

Excising epileptic foci (EF) is the most efficient approach for treating drug-resistant epilepsy (DRE). However, owing to the vast heterogeneity of epilepsies, EF in one-third of patients cannot be accurately located, even after exhausting all current diagnostic strategies. Therefore, identifying biomarkers that truly represent the status of epilepsy and fabricating probes with high targeting specificity are prerequisites for identifying the "concealed" EF. However, no systematic summary of this topic has been published. Herein, the potential biomarkers of EF are first summarized and classified into three categories: functional, molecular, and structural aberrances during epileptogenesis, a procedure of nonepileptic brain biasing toward epileptic tissue. The materials used to fabricate these imaging probes and their performance in defining the EF in preclinical and clinical studies are highlighted. Finally, perspectives for developing the next generation of probes and their challenges in clinical translation are discussed. In general, this review can be helpful in guiding the development of imaging probes defining EF with improved accuracy and holds promise for increasing the number of DRE patients who are eligible for surgical intervention.

Recent advances in small-molecule fluorescent probes for studying ferroptosis

Ferroptosis is an iron-dependent, non-apoptotic form of programmed cell death driven by excessive lipid peroxidation (LPO). Mounting evidence suggests that the unique modality of cell death is involved in the development and progression of several diseases including cancer, cardiovascular diseases (CVDs), neurodegenerative disorders, etc. However, the pathogenesis and signalling pathways of ferroptosis are not fully understood, possibly due to the lack of robust tools for the highly selective and sensitive imaging of ferroptosis analytes in complex living systems. Up to now, various small-molecule fluorescent probes have been applied as promising chemosensors for studying ferroptosis through tracking the biomolecules or microenvironment-related parameters in vitro and in vivo. In this review, we comprehensively reviewed the recent development of small-molecule fluorescent probes for studying ferroptosis, with a focus on the analytes, design strategies and bioimaging applications. We also provided new insights to overcome the major challenges in this emerging field.

Hypochlorous Acid Chemistry in Mammalian Cells—Influence on Infection and Role in Various Pathologies

This review discusses the formation of hypochlorous acid HOCl and the role of reactive chlorinated species (RCS), which are catalysed by the enzyme myeloperoxidase MPO, mainly located in leukocytes and which in turn contribute to cellular oxidative stress. The reactions of RCS with various organic molecules such as amines, amino acids, proteins, lipids, carbohydrates, nucleic acids, and DNA are described, and an attempt is made to explain the chemical mechanisms of the formation of the various chlorinated derivatives and the data available so far on the effects of MPO, RCS and halogenative stress. Their presence in numerous pathologies such as atherosclerosis, arthritis, neurological and renal diseases, diabetes, and obesity is reviewed and were found to be a feature of debilitating diseases.

Anxiolytic Effect of Carvedilol in Chronic Unpredictable Stress Model

Anxiety disorders are the most prevalent psychiatric disorders being also a comorbid state of other diseases. We aimed to evaluate the anxiolytic-like effects of carvedilol (CVD), a drug used to treat high blood pressure and heart failure with potent antioxidant effects, in animals exposed to chronic unpredictable stress (CUS). To do this, female Swiss mice were exposed to different stressors for 21 days. Between days 15 and 21, the animals received oral CVD (5 or 10 mg/kg) or the antidepressant desvenlafaxine (DVS 10 mg/kg). On the 22^nd day, behavioral tests were conducted to evaluate locomotor activity (open field) and anxiety-like alterations (elevated plus-maze—EPM and hole board—HB tests). After behavioral determinations, the animals were euthanized, and the adrenal gland, blood and brain areas, prefrontal cortex (PFC), and hippocampus were removed for biochemical analysis. CUS reduced the crossings while increased rearing and grooming, an effect reversed by both doses of CVD and DVS. CUS decreased the number of entries and permanence time in the open arms of the EPM, while all treatments reversed this effect. CUS reduced the number of head dips in the HB, an effect reversed by CVD. The CUS reduced weight gain, while only CVD5 reversed this effect. A reduction in the cortical layer size of the adrenal gland was observed in stressed animals, which CVD reversed. Increased myeloperoxidase activity (MPO) and interferon-γ (IFN-γ), as well as reduction of interleukin-4 (IL-4) induced by CUS, were reversed by CVD. DVS and CVD increased IL-6 in both brain areas. In the hippocampus, DVS caused an increase in IFN-γ. Our data show that CVD presents an anxiolytic effect partially associated with immune-inflammatory mechanism regulation.

Potential role of oxidative stress in the pathogenesis of diabetic bladder dysfunction

Diabetes mellitus is a chronic metabolic disease, posing a considerable threat to global public health. Treating systemic comorbidities has been one of the greatest clinical challenges in the management of diabetes. Diabetic bladder dysfunction, characterized by detrusor overactivity during the early stage of the disease and detrusor underactivity during the late stage, is a common urological complication of diabetes. Oxidative stress is thought to trigger hyperglycaemia-dependent tissue damage in multiple organs; thus, a growing body of literature has suggested a possible link between functional changes in urothelium, muscle and the corresponding innervations. Improved understanding of the mechanisms of oxidative stress could lead to the development of novel therapeutics to restore the redox equilibrium and scavenge excessive free radicals to normalize bladder function in patients with diabetes.

Dendrobium officinale polysaccharides attenuate uropathogenic Escherichia coli (UPEC)-induced pyroptosis in macrophage cells

Urinary tract infections (UTI) are recognized as one of the most common infectious diseases worldwide, and uropathogenic Escherichia coli (UPEC) is the main causative agent of UTI. Dendrobium officinale polysaccharides (DOPs), the main effective ingredient in Dendrobium officinale, have been reported to possess an anti-inflammatory role. Whether DOPs can attenuate the inflammatory injury (pyroptosis) induced by UPEC remains unknown. The present study aimed to assess the protective effect and potential mechanism of DOPs in UPEC-induced pyroptosis. Cell viability of THP-1 differentiated macrophage cells with DOPs was determined using MTT assay. Pyroptosis by UPEC in macrophage cells with or not DOPs pre-treatment was evaluated with flow cytometry analysis, lactate dehydrogenase (LDH) assay, and proinflammatory cytokines secretion. Expression level of key proteins in the NLRP3/Caspase-1/GSDMD pyroptotic pathway was analyzed with western blot. Furthermore the effect of DOPs on ROS activation was investigated. Results indicated that DOPs attenuated UPEC-induced cell damage in macrophage cells, inhibited the activation of NLRP3 mediated inflammasome, subsequently decreased induction and activation of caspase-1/GSDMD, and reduced the secretion of pro-inflammatory cytokine (IL-1β et al.). Moreover, pretreatment with DOPs significantly reduces ROS production, an important/putative pyroptosis stimulus signal. These results suggested that DOPs successfully mitigate UPEC-promoted pyroptosis in macrophage cells. The protective effects of DOPs are associated with the inhibition of the NLRP3/Caspase-1/GSDMD pathway and ROS signal activation.

Biomarkers Utility: At the Borderline between Cardiology and Neurology

Biomarkers are important diagnostic and prognostic tools as they provide results in a short time while still being an inexpensive, reproducible and accessible method. Their well-known benefits have placed them at the forefront of research in recent years, with new and innovative discoveries being implemented. Cardiovascular and neurological diseases often share common risk factors and pathological pathways which may play an important role in the use and interpretation of biomarkers' values. Among the biomarkers used extensively in clinical practice in cardiology, hs-TroponinT, CK-MB and NTproBNP have been shown to be strongly influenced by multiple neurological conditions. Newer ones such as galectin-3, lysophosphatidylcholine, copeptin, sST2, S100B, myeloperoxidase and GDF-15 have been extensively studied in recent years as alternatives with an increased sensitivity for cardiovascular diseases, but also with significant results in the field of neurology. Thus, given their low specificity, the values interpretation must be correlated with the clinical judgment and other available investigations.

Leptospiral meningoencephalitis in a raccoon dog

Neuroleptospirosis is a rare disease caused by pathogenic Leptospira interrogans in humans; however, it has not been fully studied in animals. A young wild raccoon dog was found convulsing in the recumbent position and died the next day. Histologic examination revealed nonsuppurative meningoencephalitis in the cerebrum, cerebellum, midbrain, and medulla oblongata. The lesions consisted of mixed infiltrates of Iba1-positive macrophages and CD3-positive T cells, with a small number of CD79α-positive B cells and myeloperoxidase-positive neutrophils. In the frontal cortex, perivascular cuffs and adjacent microglial nodules were distributed diffusely, especially in the molecular layer. Glial nodules were comprised of Iba1- and myeloperoxidase-positive activated microglia. Immunohistochemistry revealed leptospires in mononuclear cell perivascular cuffs, but not in glial nodules. Neuroleptospirosis was accompanied by Leptospira-related nonsuppurative interstitial nephritis, pulmonary edema and hemorrhage, and coronary periarteritis, as well as Toxocara tanuki in the small intestine and nonspecific foreign-body granulomas in the lungs and stomach.

Role of myeloperoxidase and oxidant formation in the extracellular environment in inflammation-induced tissue damage

The heme peroxidase family generates a battery of oxidants both for synthetic purposes, and in the innate immune defence against pathogens. Myeloperoxidase (MPO) is the most promiscuous family member, generating powerful oxidizing species including hypochlorous acid (HOCl). Whilst HOCl formation is important in pathogen removal, this species is also implicated in host tissue damage and multiple inflammatory diseases. Significant oxidant formation and damage occurs extracellularly as a result of MPO release via phagolysosomal leakage, cell lysis, extracellular trap formation, and inappropriate trafficking. MPO binds strongly to extracellular biomolecules including polyanionic glycosaminoglycans, proteoglycans, proteins, and DNA. This localizes MPO and subsequent damage, at least partly, to specific sites and species, including extracellular matrix (ECM) components and plasma proteins/lipoproteins. Biopolymer-bound MPO retains, or has enhanced, catalytic activity, though evidence is also available for non-catalytic effects. These interactions, particularly at cell surfaces and with the ECM/glycocalyx induce cellular dysfunction and altered gene expression. MPO binds with higher affinity to some damaged ECM components, rationalizing its accumulation at sites of inflammation. MPO-damaged biomolecules and fragments act as chemo-attractants and cell activators, and can modulate gene and protein expression in naïve cells, consistent with an increasing cycle of MPO adhesion, activity, damage, and altered cell function at sites of leukocyte infiltration and activation, with subsequent tissue damage and dysfunction. MPO levels are used clinically both diagnostically and prognostically, and there is increasing interest in strategies to prevent MPO-mediated damage; therapeutic aspects are not discussed as these have been reviewed elsewhere.

Increased concentrations of myeloperoxidase in serum and serum extracellular vesicles are associated with type 2 diabetes mellitus

BACKGROUND

Inflammatory response plays a critical role in the initiation and progression of type 2 diabetes mellitus (T2DM). Myeloperoxidase (MPO), a leukocyte-derived protagonist, exerts its proinflammatory properties in many complications. We explored the associations between serum extracellular vesicle (EV)-derived MPO as well as serum MPO and T2DM.

METHODS

We performed a cross-sectional study in 151 individuals, including 93 patients with T2DM and 58 non-T2DM controls. The concentrations of serum EV-derived MPO and serum MPO were measured by Luminex Assay.

RESULTS

Our data showed that serum EV-derived MPO concentrations and serum MPO concentrations were significantly higher in T2DM patients compared with non-T2DM subjects. In addition, multivariate logistic regression analysis revealed that serum EV-derived MPO as well as serum MPO was independently associated with the presence of T2DM even after adjusting for confounding factors (OR = 1.836 /1 ng EV-derived MPO, 95% CI = 1.395-2.417, P < 0.001; OR = 4.135 /10 ng serum MPO, 95% CI = 2.285-7.483, P < 0.001). Furthermore, serum MPO showed marginally higher discriminatory accuracy than serum EV-derived MPO in screening T2DM (AUC = 0.858; AUC = 0.779).

CONCLUSION

Increased concentrations of the inflammatory marker MPO either in serum or in serum EVs were independently associated with T2DM.

Predictive Value of Degranulating Factors of Neutrophils in Massive Cerebral Infarction

Massive cerebral infarction (MCI) is a life-threatening disease and may lead to cerebral herniation. Neutrophil degranulation contributes to ischemic injury in the early stage. To investigate whether neutrophil degranulating factors can predict cerebral herniation and the long-term prognosis of patients with MCI and to investigate the relationship between neutrophil degranulation and blood brain barrier (BBB) damage. In this case-control study of 14 MCI patients, we divided the patients into a cerebral hernia group and no cerebral hernia group according to whether they developed cerebral herniation within 5 days. The prognosis of MCI patients was assessed using the Modified Rankin Scale (mRS) score at 6 months, which was the primary end point. The composition of white blood cells (WBC) and degranulating factors for neutrophils in the plasma of MCI patients was determined on days 2 and 4. Baseline characteristics were comparable in both groups. The neurological functional scores and long-term prognosis showed no difference between patients with or without cerebral herniation, while the mortality rate of the cerebral hernia group in the short term was higher (P < 0.05). The WBC count, neutrophil to lymphocyte ratio (NLR) and plasma myeloperoxidase (MPO) levels of patients with cerebral hernia were significantly higher than those of patients without cerebral hernia (all P < 0.05). MPO is a better predictor of cerebral herniation, and the NLR showed superior predictive value in the prognosis of MCI patients. neutrophil degranulation may play an important role in malignant cerebral hernia during MCI. These data suggest that, MPO and the NLR might be predictive factors for cerebral herniation and the prognosis of MCI patients.

Interleukin-13 Propagates Prothrombin Kringle-2-Induced Neurotoxicity in Hippocampi In Vivo via Oxidative Stress

The present study investigated expression of endogenous interleukin-13 (IL-13) and its possible function in the hippocampus of prothrombin kringle-2 (pKr-2)-lesioned rats. Here we report that intrahippocampal injection of pKr-2 revealed a significant loss of NeuN-immunopositive (NeuN⁺) and Nissl⁺ cells in the hippocampus at 7 days after pKr-2. In parallel, pKr-2 increased IL-13 levels, which reached a peak at 3 days post pKr-2 and sustained up to 7 days post pKr-2. IL-13 immunoreactivity was seen exclusively in activated microglia/macrophages and neutrophils, but not in neurons or astrocytes. In experiments designed to explore the involvement of IL-13 in neurodegeneration, IL-13 neutralizing antibody (IL-13Nab) significantly increased survival of NeuN⁺ and Nissl⁺ cells. Accompanying neuroprotection, immunohistochemical analysis indicated that IL-13Nab inhibited pKr-2-induced expression of inducible nitric oxide synthase and myeloperoxidase within activated microglia/macrophages and neutrophils, possibly resulting in attenuation of reactive oxygen species (ROS) generation and oxidative damage of DNA and protein. The current findings suggest that the endogenous IL-13 expressed in pKr-2 activated microglia/macrophages and neutrophils might be harmful to hippocampal neurons via oxidative stress.

Myeloperoxidase Controls Bone Turnover by Suppressing Osteoclast Differentiation Through Modulating Reactive Oxygen Species Level

Myeloperoxidase (MPO) is a heme peroxidase that plays an important role in innate immunity for host defense against invading microorganisms by catalyzing hydrogen peroxide (H₂ O₂ )-mediated reactions. Although many reports indicate MPO exerts beneficial or detrimental effects on a variety of inflammatory diseases, little is known with regard to its functional role in bone homeostasis in vivo. Here, our work demonstrates that MPO was transcriptionally downregulated in response to osteoclastogenic stimuli and that exogenous alteration of MPO expression negatively regulated osteoclast (OC) differentiation in vitro. Genetic ablation of Mpo resulted in osteoporotic phenotypes and potentiated bone-resorptive capacity in mice. Mechanistically, accumulation of intracellular H₂ O₂ and reactive oxygen species (ROS) were observed in MPO deficiency, and MPO overexpression suppressed ROS production in mouse OC precursors. Moreover, a ROS scavenger Tempol inhibited the effect of MPO deficiency on OC formation and function as well as on receptor activator of nuclear factor-κB ligand (RANKL)-initiated transduction signal activation including NF-κB, mitogen-activated protein kinases (MAPKs), and Akt, indicating the increased ROS caused by MPO deficiency contributes to osteoclastogenesis. Taken together, our data demonstrate that MPO has a protective role in bone turnover by limiting osteoclastogenesis and bone resorption physiologically through modulating intracellular H₂ O₂ level. © 2020 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Integrated traditional Chinese medicine alleviates sciatica while regulating gene expression in peripheral blood

Background

Although integrated traditional Chinese medicine (TCM) has long been indicated to be effective in the treatment of sciatica and is widely used in the management of this condition, the mechanism by which integrated TCM alleviates sciatica has not yet been fully defined, and the effect of integrated TCM on gene expression in the peripheral blood of patients with sciatica is still unknown. We performed this study to investigate the effect of integrated TCM on peripheral blood gene expression in patients with sciatica and to explore new clues for studying the mechanism of integrated TCM in alleviating sciatica.

Methods

We used a microarray to identify differentially expressed genes (DEGs) in the peripheral blood of patients with sciatica and healthy controls (DEGs-baseline), bioinformatic analysis to reveal the characteristics of DEGs-baseline, and the key genes that contribute to the gene dysregulation. A microarray was also used to identify DEGs in the peripheral blood of patients with sciatica after integrated TCM treatment compared with those at baseline, and the expression levels of DEGs were validated by qRT-PCR.

Results

We identified 153 DEGs-baseline, which included 131 upregulated genes and 22 downregulated genes. Bioinformatic analysis revealed that most of the DEGs-baseline were related to immunity and the inflammatory response and that TLR4, MMP9, MPO, CAMP, RETN, TLR5, and IL1RN were key genes involved in the dysregulation of genes in the peripheral blood of patients with sciatica. The expression levels of TLR5, IL1RN, SLC8A1, RBM20, GPER1, IL27, SOCS1, and GRTP1-AS1 were decreased in the peripheral blood of patients after integrated TCM treatment compared with that at baseline, which was accompanied by relief of pain.

Conclusion

Integrated TCM treatment relieved pain while regulating the gene expression of TLR5, IL1RN, SLC8A1, RBM20, GPER1, IL27, SOCS1, and GRTP1-AS1 in the peripheral blood of patients with sciatica. Our study provides new clues for studying the mechanism of TCM in treating sciatica.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13018-021-02280-1.

Microarray analysis reveals an inflammatory transcriptomic signature in peripheral blood for sciatica

BACKGROUND

Although the pathology of sciatica has been studied extensively, the transcriptional changes in the peripheral blood caused by sciatica have not been characterized. This study aimed to characterize the peripheral blood transcriptomic signature for sciatica.

METHODS

We used a microarray to identify differentially expressed genes in the peripheral blood of patients with sciatica compared with that of healthy controls, performed a functional analysis to reveal the peripheral blood transcriptomic signature for sciatica, and conducted a network analysis to identify key genes that contribute to the observed transcriptional changes. The expression levels of these key genes were assessed by qRT-PCR.

RESULTS

We found that 153 genes were differentially expressed in the peripheral blood of patients with sciatica compared with that of healthy controls, and 131 and 22 of these were upregulated and downregulated, respectively. A functional analysis revealed that these differentially expressed genes (DEGs) were strongly enriched for the inflammatory response or immunity. The network analysis revealed that a group of genes, most of which are related to the inflammatory response, played a key role in the dysregulation of these DEGs. These key genes are Toll-like receptor 4, matrix metallopeptidase 9, myeloperoxidase, cathelicidin antimicrobial peptide, resistin and Toll-like receptor 5, and a qRT-PCR analysis validated the higher transcript levels of these key genes in the peripheral blood of patients with sciatica than in that of healthy controls.

CONCLUSION

We revealed inflammatory characteristics that serve as a peripheral blood transcriptomic signature for sciatica and identified genes that are essential for mRNA dysregulation in the peripheral blood of patients with sciatica.

Lipocalin-2 Deficiency Reduces Oxidative Stress and Neuroinflammation and Results in Attenuation of Kainic Acid-Induced Hippocampal Cell Death

The hippocampal cell death that follows kainic acid (KA)-induced seizures is associated with blood–brain barrier (BBB) leakage and oxidative stress. Lipocalin-2 (LCN2) is an iron-trafficking protein which contributes to both oxidative stress and inflammation. However, LCN2′s role in KA-induced hippocampal cell death is not clear. Here, we examine the effect of blocking LCN2 genetically on neuroinflammation and oxidative stress in KA-induced neuronal death. LCN2 deficiency reduced neuronal cell death and BBB leakage in the KA-treated hippocampus. In addition to LCN2 upregulation in the KA-treated hippocampus, circulating LCN2 levels were significantly increased in KA-treated wild-type (WT) mice. In LCN2 knockout mice, we found that the expressions of neutrophil markers myeloperoxidase and neutrophil elastase were decreased compared to their expressions in WT mice following KA treatment. Furthermore, LCN2 deficiency also attenuated KA-induced iron overload and oxidative stress in the hippocampus. These findings indicate that LCN2 may play an important role in iron-related oxidative stress and neuroinflammation in KA-induced hippocampal cell death.

The effects of neutrophil-generated hypochlorous acid and other hypohalous acids on host and pathogens

Neutrophils are predominant immune cells that protect the human body against infections by deploying sophisticated antimicrobial strategies including phagocytosis of bacteria and neutrophil extracellular trap (NET) formation. Here, we provide an overview of the mechanisms by which neutrophils kill exogenous pathogens before we focus on one particular weapon in their arsenal: the generation of the oxidizing hypohalous acids HOCl, HOBr and HOSCN during the so-called oxidative burst by the enzyme myeloperoxidase. We look at the effects of these hypohalous acids on biological systems in general and proteins in particular and turn our attention to bacterial strategies to survive HOCl stress. HOCl is a strong inducer of protein aggregation, which bacteria can counteract by chaperone-like holdases that bind unfolding proteins without the need for energy in the form of ATP. These chaperones are activated by HOCl through thiol oxidation (Hsp33) or N-chlorination of basic amino acid side-chains (RidA and CnoX) and contribute to bacterial survival during HOCl stress. However, neutrophil-generated hypohalous acids also affect the host system. Recent studies have shown that plasma proteins act not only as sinks for HOCl, but get actively transformed into modulators of the cellular immune response through N-chlorination. N-chlorinated serum albumin can prevent aggregation of proteins, stimulate immune cells, and act as a pro-survival factor for immune cells in the presence of cytotoxic antigens. Finally, we take a look at the emerging role of HOCl as a potential signaling molecule, particularly its role in neutrophil extracellular trap formation.

Exosomes Derived from MicroRNA-146a-5p-Enriched Bone Marrow Mesenchymal Stem Cells Alleviate Intracerebral Hemorrhage by Inhibiting Neuronal Apoptosis and Microglial M1 Polarization

Introduction

Intracerebral hemorrhage (ICH) is a devastating type of stroke with high mortality, and the effective therapies for ICH remain to be explored. Exosomes (Exos) have been found to play important roles in cell communication by transferring molecules, including microRNAs (miRNAs/miRs). MiRNAs are critical regulators of genes involved in many various biological processes and have been demonstrated to aggravate or alleviate brain damages induced by ICH. The aim of the present study was to investigate the effect of Exos derived from miR-146a-5p-enriched bone marrow mesenchymal stem cells (BMSCs-miR-146a-5p-Exos) on experimental ICH.

Methods

ICH was induced in adult male Sprague-Dawley rats by an intrastriatal injection of collagenase type IV. At 24 h after surgery, Exos were administrated. For detecting apoptotic cells, TUNEL staining was performed using an in situ Cell Death Detection Kit. Fluoro-Jade B staining was performed to detect degenerating neurons. Immunofluorescence assay was performed to detect the expression of myeloperoxidase (MPO) and OX-42. The binding of miR-146a-5p and its target genes was confirmed by luciferase reporter assay.

Results

At 24 h after surgery, BMSCs-miR-146a-5p-Exos administration significantly improved neurological function, reduced apoptotic and degenerative neurons, and inhibited inflammatory response. Furthermore, miR-146a-5p-enriched Exos obviously inhibited the M1 polarization of microglia after ICH in rats, accompanied by the reduced expression of pro-inflammatory mediators releasing by M1 microglia including inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2) and monocyte chemoattractant protein-1 (MCP-1). Finally, we observed that miR-146a-5p directly targeted interleukin-1 receptor-associated kinase1 (IRAK1) and nuclear factor of activated T cells 5 (NFAT5), which contributed to the inflammation response and the polarization of M1 microglia/macrophages.

Conclusion

We demonstrated that miR-146a-5p-riched BMSCs-Exos could offer neuroprotection and functional improvements after ICH through reducing neuronal apoptosis, and inflammation associated with the inhibition of microglial M1 polarization by downregulating the expression of IRAK1 and NFAT5.

Decreased neutrophil levels in mice with traumatic brain injury after cape administration

Introduction

Peripheral leukocytes can worsen brain damage due to the release of cytotoxic mediators that interfere the blood brain barrier function. One of the oxidants released by activation leukocyte is hypochlorite acid (HOCl) which is formed through the myeloperoxidase (MPO)-H2O2–Cl^- system. The neuroprotective effects of an experimental anti-inflammatory drug Caffeic Acid Phenethyl Ester (CAPE) tested in a Traumatic brain injury (TBI) model using Myeloperoxidase (MPO) analysis.

Methods

This study compares the acute inflammatory response to TBI over time, as measured by MPO activity. Adult Sprague mice were treated for head trauma with marmarou model. At 24 h before trauma, all animals were blood test (n = 10) to examine MPO, then the animal was divided into 2 groups of injured animals treated with CAPE (n = 5), and those not treated with CAPE (n = 5). We used the MPO test to identify the level of polymorphonuclear leukocytes (PMNL) on day 4 and day 7.

Results

Showed an increase in PMNL infiltration in CAPE untreated animals, this change significantly (P < 0.05) decreased at group of animals treated with CAPE. MPO serum activity in the CAPE untreated group vs treated with CAPE on day 4 ± 11920410.076 (Standard deviation {SD} 895355.169) vs 6663184.485 (SD 895355.169) p < 0,05 and on day 7 ± 14223286.992 (SD 802762.401) vs 9284222.028 (SD 953098.093) p < 0,05. These data indicate that MPO activity after TBI increases on day 4 also on day 7 and improves after being treated with CAPE.

Conclusion

CAPE can reduce Neutrophil serum levels there by preventing brain damage in TBI.

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Peripheral leukocytes can worsen brain damage due to the release of cytotoxic mediators that interfere the blood brain barrier function.

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One of the oxidants released by activation leukocyte is HOCl which is formed through the MPO-H2O2–Cl-system.

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CAPE administration in mice with traumatic brain injury can inhibit the formation of myeloperoxidase as a marker of accumulated neutrophils.

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CAPE can reduce Neutrophil serum levels there by preventing brain damage in TBI.

The Role of Myeloperoxidase in Biomolecule Modification, Chronic Inflammation, and Disease

Significance: The release of myeloperoxidase (MPO) by activated leukocytes is critical in innate immune responses. MPO produces hypochlorous acid (HOCl) and other strong oxidants, which kill bacteria and other invading pathogens. However, MPO also drives the development of numerous chronic inflammatory pathologies, including atherosclerosis, neurodegenerative disease, lung disease, arthritis, cancer, and kidney disease, which are globally responsible for significant patient mortality and morbidity. Recent Advances: The development of imaging approaches to precisely identify the localization of MPO and the molecular targets of HOCl in vivo is an important advance, as typically the involvement of MPO in inflammatory disease has been inferred by its presence, together with the detection of biomarkers of HOCl, in biological fluids or diseased tissues. This will provide valuable information in regard to the cell types responsible for releasing MPO in vivo, together with new insight into potential therapeutic opportunities. Critical Issues: Although there is little doubt as to the value of MPO inhibition as a protective strategy to mitigate tissue damage during chronic inflammation in experimental models, the impact of long-term inhibition of MPO as a therapeutic strategy for human disease remains uncertain, in light of the potential effects on innate immunity. Future Directions: The development of more targeted MPO inhibitors or a treatment regimen designed to reduce MPO-associated host tissue damage without compromising pathogen killing by the innate immune system is therefore an important future direction. Similarly, a partial MPO inhibition strategy may be sufficient to maintain adequate bacterial activity while decreasing the propagation of inflammatory pathologies.

Epileptic brain fluorescent imaging reveals apigenin can relieve the myeloperoxidase-mediated oxidative stress and inhibit ferroptosis

Myeloperoxidase (MPO)-mediated oxidative stress has been suggested to play an important role in the pathological dysfunction of epileptic brains. However, there is currently no robust brain-imaging tool to detect real-time endogenous hypochlorite (HClO) generation by MPO or a fluorescent probe for rapid high-throughput screening of antiepileptic agents that control the MPO-mediated chlorination stress. Herein, we report an efficient two-photon fluorescence probe (named HCP) for the real-time detection of endogenous HClO signals generated by MPO in the brain of kainic acid (KA)-induced epileptic mice, where HClO-dependent chlorination of quinolone fluorophore gives the enhanced fluorescence response. With this probe, we visualized directly the endogenous HClO fluxes generated by the overexpression of MPO activity in vivo and ex vivo in mouse brains with epileptic behaviors. Notably, by using HCP, we have also constructed a high-throughput screening approach to rapidly screen the potential antiepileptic agents to control MPO-mediated oxidative stress. Moreover, from this screen, we identified that the flavonoid compound apigenin can relieve the MPO-mediated oxidative stress and inhibit the ferroptosis of neuronal cells. Overall, this work provides a versatile fluorescence tool for elucidating the role of HClO generation by MPO in the pathology of epileptic seizures and for rapidly discovering additional antiepileptic agents to prevent and treat epilepsy.

Endoplasmic reticulum-mitochondria crosstalk: from junction to function across neurological disorders

The endoplasmic reticulum (ER) and mitochondria are fundamental organelles highly interconnected with a specialized set of proteins in cells. ER-mitochondrial interconnections form specific microdomains, called mitochondria-associated ER membranes, that have been found to play important roles in calcium signaling and lipid homeostasis, and more recently in mitochondrial dynamics, inflammation, and autophagy. It is not surprising that perturbations in ER-mitochondria connections can result in the progression of disease, especially neurological disorders; hence, their architecture and regulation are crucial in determining the fate of cells and disease. The molecular identity of the specialized proteins regulating ER-mitochondrial crosstalk remains unclear. Our discussion here describes the physical and functional crosstalk between these two dynamic organelles and emphasizes the outcome of altered ER-mitochondrial interconnections in neurological disorders.

Intra-arterial stem cell therapy modulates neuronal calcineurin and confers neuroprotection after ischemic stroke

Aim: Calcineurin (CaN) is a threonine/phosphatase which play roles in neuronal homeostasis. Ischemic stroke induces hyperactivation of CaN which further triggers apoptotic signaling. CaN inhibition has limited therapeutic output and neurotoxicity due to its intricate roles in the neuronal network and requires a strategic modulation. Intra-arterial (IA) mesenchymal stem cells (MSCs) have shown to interact with the milieu in a paracrine manner as compared to CaN inhibitors to ameliorate the neuronal damage triggered by ischemia/reperfusion injury. The present study investigates the role of IA MSCs in modulating neuronal CaN after stroke onset. Materials and methods: To validate, middle-aged ovariectomized female rats exposed to MCAo (90 min) were treated with IA MSCs (1 × 10⁵ MSCs) or phosphate-buffered saline (PBS) at 6 hours to check CaN expression in different groups.Tests for assessing functional and motor coordination were performed along with biochemical estimations. Furthermore, an inhibition study by non-selective inhibitor of neuronal calcium channel, flunarizine, was performed to explore the possible underlying mechanism by which IA MSCs may interact with CaN. Results: The study suggests that IA MSCs seemingly reduce the expression of CaN after ischemic stroke. IA MSCs have shown to improve the functional outcome and normalize oxidative parameters. Conclusion: Our study provides a preliminary evidence of role of IA MSCs in modulating CaN expression.

Evolving Evidence of Calreticulin as a Pharmacological Target in Neurological Disorders

Calreticulin (CALR), a lectin-like ER chaperone, was initially known only for its housekeeping function, but today it is recognized for many versatile roles in different compartments of a cell. Apart from canonical roles in protein folding and calcium homeostasis, it performs a variety of noncanonical roles, mostly in CNS development. In the past, studies have linked Calreticulin with various other biological components which are detrimental in deciding the fate of neurons. Many neurological disorders that differ in their etiology are commonly associated with aberrant levels of Calreticulin, that lead to modulation of apoptosis and phagocytosis, and impact on transcriptional pathways, impairment in proteostatis, and calcium imbalances. Such multifaceted properties of Calreticulin are the reason why it has been implicated in vital roles of the nervous system in recent years. Hence, understanding its role in the physiology of neurons would help to unearth its involvement in the spectrum of neurological disorders. This Review aims toward exploring the interplay of Calreticulin in neurological disorders which would aid in targeting Calreticulin for developing novel neurotherapeutics.

Interplay between Mitophagy and Inflammasomes in Neurological Disorders

Mitophagy and inflammasomes have a pivotal role in the development of neuropathology. Molecular mechanisms behind mitophagy and inflammasomes are well-understood, but lacunae prevail in understanding the crosstalk between them in various neurological disorders. As mitochondrial dysfunction is the prime event in neurodegeneration, the clearance of impaired mitochondria is one of the main tasks for maintaining cell integrity in the majority of neuropathologies. Along with it, inflammasome activation also plays a major role, which is usually followed by mitochondrial dysfunction. The present review highlights basics of autophagy, mitophagy, and inflammasomes and the molecular mechanisms involved, and more importantly, it tries to elaborate the interplay between mitophagy and inflammasomes in various neurological disorders. This will help in upgrading the reader's understanding in exploring the link between mitophagy and inflammasomes, which has dealt with limitations in past studies.

Trigonelline therapy confers neuroprotection by reduced glutathione mediated myeloperoxidase expression in animal model of ischemic stroke

AIM

Stroke is devastating with a limited choice of intervention. Many pharmacological entities are available but none of them have evolved successfully in counteracting the multifaceted molecular alterations following stroke. Myeloperoxidase (MPO) has been reported to play an important role in neuroinflammation following neurodegenerative diseases. Therefore, using it as a therapeutic target may be a strategy to confer neuroprotection in stroke. Trigonelline (TG), a plant alkaloid has shown neuroprotective effects in the past. Here we explore its neuroprotective effects and its role in glutathione mediated MPO inhibition in ischemic stroke.

METHODS

An in silico study was performed to confirm effective TG and MPO interaction. An in vitro evaluation of toxicity with biochemical estimations was performed. Further, in vivo studies were undertaken where rats were treated with 25, 50 and 100 mg/kg TG or standard MPO inhibiting drug4‑Aminobenzoic hydrazide (4‑ABH) at 60 min prior, post immediate and an hour post 90 min of middle cerebral artery occlusion (MCAo) followed by 24 h reperfusion. Rats were evaluated for neurodeficit and motor function tests. Brains were further harvested for infarct size evaluation, biochemical analysis, and western blot experiments.

KEY FINDINGS

TG at 100 mg/kg dose i.p. administered immediately post ischemia confers neuroprotection by reducing cerebral infarct with improvement in motor and neurodeficit scores. Furthermore, elevated nitrite and MDA levels were also found to be reduced in brain regions in the treated group. TG also potentiated intrinsic antioxidant status and markedly inhibited reduced glutathione mediated myeloperoxidase expression in the cortical brain region.

SIGNIFICANCE

TG confers neuroprotection by reduced glutathione mediated myeloperoxidase inhibition in ischemic stroke.

Mitochondrial Dysfunction in Stroke: Implications of Stem Cell Therapy

Stroke is a debilitating condition which is also the second leading cause of death and disability worldwide. Despite the benefits and promises shown by numerous neuroprotective agents in animal stroke models, their clinical translation has not been a complete success. Hence, search for treatment options have directed researchers towards utilising stem cells. Mitochondria has a major involvement in the pathophysiology of stroke and a number of other conditions. Stem cells have shown the ability to transfer mitochondria to the damaged cells and to help revive cell energetics in the recipient cell. The present review discusses how stem cells could be employed to protect neurons and mitochondria in stroke and also the various mechanisms involved in neuroprotection.

Midday and nadir salivary cortisol appear superior to cortisol awakening response in burnout assessment and monitoring

Burnout and work-related stress symptoms of anxiety disorder and depression cause prolonged work absenteeism and early retirement. Hence, reliable identification of patients under risk and monitoring of treatment success is highly warranted. We aimed to evaluate stress-specific biomarkers in a population-based, “real-world” cohort (burnouts: n = 40, healthy controls: n = 26), recruited at a preventive care ward, at baseline and after a four-month follow up, during which patients received medical and psychological treatment. At baseline, significantly higher levels of salivary cortisol were observed in the burnout group compared to the control group. This was even more pronounced in midday- (p < 0.001) and nadir samples (p < 0.001) than for total morning cortisol secretion (p < 0.01). The treatment program resulted in a significant reduction of stress, anxiety, and depression scores (all p < 0.001), with 60% of patients showing a clinically relevant improvement. This was accompanied by a ~30% drop in midday cortisol levels (p < 0.001), as well as a ~25% decrease in cortisol nadir (p < 0.05), although not directly correlating with score declines. Our data emphasize the potential usefulness of midday and nadir salivary cortisol as markers in the assessment and biomonitoring of burnout.