The antioxidant role of thiocyanate in the pathogenesis of cystic fibrosis and other inflammation-related diseases

Analytical developments in the synergism of copper particles and cysteine: a review

Cysteine, a sulfur-containing amino acid, is a vital candidate for physiology. Coinage metal particles (both clusters and nanoparticles) are highly interesting for their spectacular plasmonic properties. In this case, copper is the most important candidate for its cost-effectiveness and abundance. However, rapid oxidation destroys the stability of copper particles, warranting the necessity of suitable capping agents and experimental conditions. Cysteine can efficiently carry out such a role. On the contrary, cysteine sensing is a vital step for biomedical science. This review article is based on a comparative account of copper particles with cysteine passivation and copper particles for cysteine sensing. For the deep understanding of readers, we discuss nanoparticles and nanoclusters, properties of cysteine, and importance of capping agents, along with various synthetic protocols and applications (sensing and bioimaging) of cysteine-capped copper particles (cysteine-capped copper nanoparticles and cysteine-capped copper nanoclusters). We also include copper nanoparticles and copper nanoclusters for cysteine sensing. As copper is a plasmonic material, fluorometric and colorimetric methods are mostly used for sensing. Real sample analysis for both copper particles with cysteine and copper particles for cysteine sensing are also incorporated in this review to demonstrate their practical applications. Both cysteine-capped copper particles and copper particles for cysteine sensing are the main essence of this review. The aspect of the synergism of copper and cysteine (unlike other amino acids) is quite promising for future researchers.

Design a Friendly Nanoscale Chemical Sensor Based on Gold Nanoclusters for Detecting Thiocyanate Ions in Food Industry Applications

The surfactant cetyltrimethylammonium bromide (CTAB) induces the aggregation of gold nanoclusters (GNCs), leading to the development of a proposed fluorometric technique for detecting thiocyanate (SCN-) ions based on an anti-aggregation mechanism. This approach is straightforward to execute, highly sensitive, and selective. A significant quenching effect occurs in fluorescence upon using the aggregation agent CTAB in GNCs synthesis, resulting in a transition from intense red fluorescence to dim red. The decrease in fluorescence intensity of GNCs in the presence of CTAB is caused by the mechanism of fluorescence quenching mediated by aggregation. As the levels of SCN- rise, the fluorescence of CTAB-GNCs increases; this may be detected using spectrofluorometry or by visually inspecting under UV irradiation. The recovery of red fluorescence of CTAB-GNCs in the presence of SCN- enables the precise and discerning identification of SCN- within the concentration range of 2.86-140 nM. The minimum detectable concentration of the SCN- ions was 1 nM. The selectivity of CTAB-GNCs towards SCN- ions was investigated compared to other ions, and it was demonstrated that CTAB-GNCs exhibit exceptional selectivity. Furthermore, we believe that CTAB-GNCs have novel possibilities as favorable sensor candidates for various industrial applications. Our detection technique was validated by analyzing SCN- ions in milk samples, which yielded promising results.

Multifunctional (4-in-1) Therapeutic Applications of Nickel Thiocyanate Nanoparticles Impregnated Cotton Gauze as Antibacterial, Antibiofilm, Antioxidant and Wound Healing Agent

The wounds, arises from accidents, burns, surgeries, diabetes, and trauma, can significantly impact well-being and present persistent clinical challenges. Ideal wound dressings should be flexible, stable, antibacterial, antioxidant and anti-inflammatory in nature, facilitating a scarless rapid wound healing. Initiatives were taken to create antibacterial cotton fabrics by incorporating agents like antibiotics and metallic nanoparticles. However, due to a lack of multifunctionality, these materials were not highly effective in causing scarless and rapid wound healing. In this article, nickel thiocyanate nanoparticle (NiSCN-NPs) impregnated cotton gauze wound dressing (NiSCN-CG) was developed. These nanoparticles were non-toxic to normal human cell lines till 1 mg/mL dose and did not cause skin irritation in the rat model. Further, NiSCN-NPs exhibited antimicrobial, antibiofilm and antioxidant activities confirmed using different in vitro experiments. In vivo wound healing studies in rat models using NiSCN-CG demonstrated rapid scarless wound healing. The nickel thiocyanate impregnated cotton gauze presents a novel approach in scarless wound healing, and as an antimicrobial agent, offering a promising solution for diverse wounds and infections in the future.

CFTR dysfunction leads to defective bacterial eradication on cystic fibrosis airways

Dysfunction of the cystic fibrosis transmembrane conductance regulator (CFTR) anion channel by genetic mutations causes the inherited disease cystic fibrosis (CF). CF lung disease that involves multiple disorders of epithelial function likely results from loss of CFTR function as an anion channel conducting chloride and bicarbonate ions and its function as a cellular regulator modulating the activity of membrane and cytosol proteins. In the absence of CFTR activity, abundant mucus accumulation, bacterial infection and inflammation characterize CF airways, in which inflammation-associated tissue remodeling and damage gradually destroys the lung. Deciphering the link between CFTR dysfunction and bacterial infection in CF airways may reveal the pathogenesis of CF lung disease and guide the development of new treatments. Research efforts towards this goal, including high salt, low volume, airway surface liquid acidosis and abnormal mucus hypotheses are critically reviewed.

Associations of perchlorate, nitrate, and thiocyanate exposure with arthritis and inflammation indicators in young and middle-aged adults, NHANES 2005-2016

Background

Perchlorates, nitrates, and thiocyanates are prevalent environmental chemicals. Their potential association with arthritis remains unexplored. This study aimed to investigate the link between perchlorate, nitrate, and thiocyanate exposure and arthritis, as well as the potential role of inflammation in this context.

Methods

Utilizing the National Health and Nutrition Examination Survey (NHANES) data spanning from 2005 to 2016, the study enrolled 6597 participants aged 20-59 (young and middle-aged), of which 1045 had arthritis. Employing multivariate logistic regression modeling, multiple linear regression models, restricted cubic spline analysis, Bayesian kernel machine regression (BKMR) modeling, and mediation analysis, we assessed these relationships.

Results

There was a significant positive association between elevated urinary thiocyanate levels and arthritis risk [1.19 (1.11, 1.28)]. This association held true across subgroups of osteoarthritis (OA) [1.24 (1.10, 1.40)] and rheumatoid arthritis (RA) [1.33 (1.15, 1.55)]. Thiocyanate levels displayed a dose-dependent relationship with arthritis risk, showing a linear trend (nonlinear P > 0.05). Conversely, perchlorate and nitrate did not exhibit associations with arthritis risk. BKMR outcomes highlighted a positive correlation between a mixture of perchlorate, nitrate, and thiocyanate and arthritis risk, with thiocyanate being the predominant predictors. Moreover, BKMR and generalized linear model analyses unveiled no significant synergistic effect of urinary perchlorate, nitrate, and thiocyanate on arthritis risk. Furthermore, thiocyanate exposure has been linked to elevated levels of inflammatory indicators (white blood cell, neutrophils, lymphocytes, and systemic immune-inflammatory index (SII)).

Conclusion

Heightened thiocyanate exposure may be linked to elevated arthritis risk, either single or in combined effects. Additionally, thiocyanate exposure is associated with heightened inflammation levels.

The Roles of Neutrophil-Derived Myeloperoxidase (MPO) in Diseases: The New Progress

Myeloperoxidase (MPO) is a heme-containing peroxidase, mainly expressed in neutrophils and, to a lesser extent, in monocytes. MPO is known to have a broad bactericidal ability via catalyzing the reaction of Cl- with H2O2 to produce a strong oxidant, hypochlorous acid (HOCl). However, the overproduction of MPO-derived oxidants has drawn attention to its detrimental role, especially in diseases characterized by acute or chronic inflammation. Broadly speaking, MPO and its derived oxidants are involved in the pathological processes of diseases mainly through the oxidation of biomolecules, which promotes inflammation and oxidative stress. Meanwhile, some researchers found that MPO deficiency or using MPO inhibitors could attenuate inflammation and tissue injuries. Taken together, MPO might be a promising target for both prognostic and therapeutic interventions. Therefore, understanding the role of MPO in the progress of various diseases is of great value. This review provides a comprehensive analysis of the diverse roles of MPO in the progression of several diseases, including cardiovascular diseases (CVDs), neurodegenerative diseases, cancers, renal diseases, and lung diseases (including COVID-19). This information serves as a valuable reference for subsequent mechanistic research and drug development.

Substrate-dependent metabolomic signatures of myeloperoxidase activity in airway epithelial cells: Implications for early cystic fibrosis lung disease

Myeloperoxidase (MPO) is released by neutrophils in inflamed tissues. MPO oxidizes chloride, bromide, and thiocyanate to produce hypochlorous acid (HOCl), hypobromous acid (HOBr), and hypothiocyanous acid (HOSCN), respectively. These oxidants are toxic to pathogens, but may also react with host cells to elicit biological activity and potential toxicity. In cystic fibrosis (CF) and related diseases, increased neutrophil inflammation leads to increased airway MPO and airway epithelial cell (AEC) exposure to its oxidants. In this study, we investigated how equal dose-rate exposures of MPO-derived oxidants differentially impact the metabolome of human AECs (BEAS-2B cells). We utilized enzymatic oxidant production with rate-limiting glucose oxidase (GOX) coupled to MPO, and chloride, bromide (Br-), or thiocyanate (SCN-) as substrates. AECs exposed to GOX/MPO/SCN- (favoring HOSCN) were viable after 24 h, while exposure to GOX/MPO (favoring HOCl) or GOX/MPO/Br- (favoring HOBr) developed cytotoxicity after 6 h. Cell glutathione and peroxiredoxin-3 oxidation were insufficient to explain these differences. However, untargeted metabolomics revealed GOX/MPO and GOX/MPO/Br- diverged significantly from GOX/MPO/SCN- for dozens of metabolites. We noted methionine sulfoxide and dehydromethionine were significantly increased in GOX/MPO- or GOX/MPO/Br--treated cells, and analyzed them as potential biomarkers of lung damage in bronchoalveolar lavage fluid from 5-year-olds with CF (n = 27). Both metabolites were associated with increasing bronchiectasis, neutrophils, and MPO activity. This suggests MPO production of HOCl and/or HOBr may contribute to inflammatory lung damage in early CF. In summary, our in vitro model enabled unbiased identification of exposure-specific metabolite products which may serve as biomarkers of lung damage in vivo. Continued research with this exposure model may yield additional oxidant-specific biomarkers and reveal explicit mechanisms of oxidant byproduct formation and cellular redox signaling.

Hypothiocyanite and host-microbe interactions

The pseudohypohalous acid hypothiocyanite/hypothiocyanous acid (OSCN^- /HOSCN) has been known to play an antimicrobial role in mammalian immunity for decades. It is a potent oxidant that kills bacteria but is non-toxic to human cells. Produced from thiocyanate (SCN^- ) and hydrogen peroxide (H₂ O₂ ) in a variety of body sites by peroxidase enzymes, HOSCN has been explored as an agent of food preservation, pathogen killing, and even improved toothpaste. However, despite the well-recognized antibacterial role HOSCN plays in host-pathogen interactions, little is known about how bacteria sense and respond to this oxidant. In this work, we will summarize what is known and unknown about HOSCN in innate immunity and recent advances in understanding the responses that both pathogenic and non-pathogenic bacteria mount against this antimicrobial agent, highlighting studies done with three model organisms, Escherichia coli, Streptococcus spp., and Pseudomonas aeruginosa.

Characterization of a novel dual murine model of chemotherapy-induced oral and intestinal mucositis

Oral and intestinal mucositis are debilitating inflammatory diseases observed in cancer patients undergoing chemo-radiotherapy. These are devastating clinical conditions which often lead to treatment disruption affecting underlying malignancy management. Although alimentary tract mucositis involves the entire gastrointestinal tract, oral and intestinal mucositis are often studied independently utilizing distinct organ-specific pre-clinical models. This approach has however hindered the development of potentially effective whole-patient treatment strategies. We now characterize a murine model of alimentary tract mucositis using 5-Fluorouracil (5-FU). Mice were given 5-FU intravenously (50 mg/kg) or saline every 48 h for 2 weeks. Post initial injection, mice were monitored clinically for weight loss and diarrhea. The incidence and extent of oral mucositis was assessed macroscopically. Microscopical and histomorphometric analyses of the tongue and intestinal tissues were conducted at 3 interim time points during the experimental period. Repeated 5-FU treatment caused severe oral and intestinal atrophy, including morphological damage, accompanied by body weight loss and mild to moderate diarrhea in up to 77.8% of mice. Oral mucositis was clinically evident throughout the observation period in 88.98% of mice. Toluidine blue staining of the tongue revealed that the ulcer size peaked at day-14. In summary, we have developed a model reproducing the clinical and histologic features of both oral and intestinal mucositis, which may represent a useful in vivo pre-clinical model for the study of chemotherapy-induced alimentary tract mucositis and the development of preventative therapies.

Extraction of Bioactive Compounds from Different Vegetable Sprouts and Their Potential Role in the Formulation of Functional Foods against Various Disorders: A Literature-Based Review

In this review, we discuss the advantages of vegetable sprouts in the development of food products as well as their beneficial effects on a variety of disorders. Sprouts are obtained from different types of plants and seeds and various types of leafy, root, and shoot vegetables. Vegetable sprouts are enriched in bioactive compounds, including polyphenols, antioxidants, and vitamins. Currently, different conventional methods and advanced technologies are used to extract bioactive compounds from vegetable sprouts. Due to some issues in traditional methods, increasingly, the trend is to use recent technologies because the results are better. Applications of phytonutrients extracted from sprouts are finding increased utility for food processing and shelf-life enhancement. Vegetable sprouts are being used in the preparation of different functional food products such as juices, bread, and biscuits. Previous research has shown that vegetable sprouts can help to fight a variety of chronic diseases such as cancer and diabetes. Furthermore, in the future, more research is needed that explores the extraordinary ways in which vegetable sprouts can be incorporated into green-food processing and preservation for the purpose of enhancing shelf-life and the formation of functional meat products and substitutes.

Influence of plasma halide, pseudohalide and nitrite ions on myeloperoxidase-mediated protein and extracellular matrix damage

Myeloperoxidase (MPO) mediates pathogen destruction by generating the bactericidal oxidant hypochlorous acid (HOCl). Formation of this oxidant is however associated with host tissue damage and disease. MPO also utilizes H₂O₂ to oxidize other substrates, and we hypothesized that mixtures of other plasma anions, including bromide (Br^-), iodide (I^-), thiocyanate (SCN^-) and nitrite (NO₂^-), at normal or supplemented concentrations, might modulate MPO-mediated HOCl damage. For the (pseudo)halide anions, only SCN^- significantly modulated HOCl formation (IC₅₀ ∼33 μM), which is within the normal physiological range, as judged by damage to human plasma fibronectin or extracellular matrix preparations detected by ELISA and LC-MS. NO₂^- modulated HOCl-mediated damage, in a dose-dependent manner, at physiologically-attainable anion concentrations. However, this was accompanied by increased tyrosine and tryptophan nitration (detected by ELISA and LC-MS), and the overall extent of damage remained approximately constant. Increasing NO₂^- concentrations (0.5-20 μM) diminished HOCl-mediated modification of tyrosine and methionine, whereas tryptophan loss was enhanced. At higher NO₂^- concentrations, enhanced tyrosine and methionine loss was detected. These analytical data were confirmed in studies of cell adhesion and metabolic activity. Together, these data indicate that endogenous plasma levels of SCN^- (but not Br^- or I^-) can modulate protein modification induced by MPO, including the extent of chlorination. In contrast, NO₂^- alters the type of modification, but does not markedly decrease its extent, with chlorination replaced by nitration. These data also indicate that MPO could be a major source of nitration in vivo, and particularly at inflammatory sites where NO₂^- levels are often elevated.

In Vivo Growth Inhibition of Human Caucasian Prostate Adenocarcinoma in Nude Mice Induced by Amygdalin with Metabolic Enzyme Combinations

Cancer of the prostate is an indicated type that is often recorded as a kind of cancer in men and the second critical cause of mortality through cancer cases. Many pharmacological investigations have shown that numerous herbal substances possess anticancer action. Amygdalin (AMD) has antitumour capabilities and works as an antioxidant, antibacterial, anti-inflammatory, and immune-regulating characteristics. The anticancer effects of amygdalin and its metabolizing enzymes, rhodanese (RHD) and betaglucosidase (BGD), were examined in vivo, as well as their antitumour processes. Novel, effective combination agents are necessary to increase existing cancer treatment rates. This research was aimed at determining the anticarcinogenic impact of amygdalin (AMD) in vivo. This research was aimed at determining the RHD and BGD on the anticarcinogenic impact of AMD in vivo. Subcutaneously, PC3 prostate cancer cell lines were implanted into nude mice. Mice were treated every day with 0.5 ml of 50 mg/ml (AMD), AMD+ (RHD 0.1 mg/ml), AMD+(BGD 0.1 mg/ml), and doxorubicin (DOX 50 mg/ml). Mice were normalized for negative control with untreated mice. In in vivo, morphopathological alterations in the tumour tissue were analyzed by histopathological staining methods. After 35 days of therapy, tumour growth and size inhibition were evident, indicating a function for the metabolic enzymes BGD and RHD in regulating AMD's anticancer effect in vivo. We concluded the critical role of metabolic enzymes BGD and RHD in elevating the antigrowth of PC3 cancer cell lines in Balb/c nude mice treated with AMD.

Advances in PSMA theranostics

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PSMA is an appealing target for theranostic because it is a transmembrane protein with a known substrate that is overexpessed on prostate cancer cells and internalizes upon ligand binding.

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There are a number of PSMA theranostic ligands in clinical evaluation, clinical trial, or clinically approved.

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PSMA theranostic ligands increase progression-free survival, overall survival, and pain in patients with metastatic castration resistant prostate cancer.

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A major obstacle to PSMA-targeted radioligand therapy is off-target toxicity in salivary glands.

The validation of prostate specific membrane antigen (PSMA) as a molecular target in metastatic castration-resistant prostate cancer has stimulated the development of multiple classes of theranostic ligands that specifically target PSMA. Theranostic ligands are used to image disease or selectively deliver cytotoxic radioactivity to cells expressing PSMA according to the radioisotope conjugated to the ligand. PSMA theranostics is a rapidly advancing field that is now integrating into clinical management of prostate cancer patients. In this review we summarize published research describing the biological role(s) and activity of PSMA, highlight the most clinically advanced PSMA targeting molecules and biomacromolecules, and identify next generation PSMA ligands that aim to further improve treatment efficacy. The goal of this review is to provide a comprehensive assessment of the current state-of-play and a roadmap to achieving further advances in PSMA theranostics.

Positively Charged Gold Quantum Dots: An Nanozymatic "Off-On" Sensor for Thiocyanate Detection

The concentration of thiocyanate (SCN⁻) in bodily fluids is a good indicator of potential and severe health issues such as nasal bleeding, goiters, vertigo, unconsciousness, several inflammatory diseases, and cystic fibrosis. Herein, a visual SCN⁻ sensing method has been developed using the enzyme-like nature of positively charged gold quantum dots (Au QDs) mixed with 3,3′,5,5′-tetramethylbenzidine (TMB) and hydrogen peroxide (H₂O₂₎. This research also reports a new method of synthesizing positively charged Au QDs directly from gold nanoparticles through a hydrothermal process. Microscopic imaging has showed that the Au QDs were 3–5 nm in size, and the emission wavelength was at 438 nm. Au QDs did not display any enzyme-like nature while mixed up with TMB and H₂O₂. However, the nanozymatic activity of Au QDs appeared when SCN⁻ was included, leading to a very low detection limit (LOD) of 8 nM and 99–105% recovery in complex media. The steady-state kinetic reaction of Au QDs showed that Au QDs had a lower Michaelis–Menten constant (Km) toward H₂O₂ and TMB, which indicates that the Au QDs had a higher affinity for H₂O₂ and TMB than horseradish peroxidase (HRP). A mechanism study has revealed that the scavenging ability of hydroxyl (•OH) radicals by the SCN⁻ group plays an important role in enhancing the sensitivity in this study. The proposed nanozymatic “Off–On” SCN⁻ sensor was also successfully validated in commercial milk samples.

Resistance of Streptococcus pneumoniae to hypothiocyanous acid generated by host peroxidases

Streptococcus pneumoniae is a serious human respiratory pathogen. It generates hydrogen peroxide (H₂O₂) as part of its normal metabolism, yet it lacks enzymes that remove this oxidant. Here we show that lactoperoxidase and myeloperoxidase, two host enzymes present in the respiratory tract, convert bacterial H₂O₂ into HOSCN that S. pneumoniae can resist. We found that incubation of S. pneumoniae with myeloperoxidase in chloride-rich buffer killed the bacteria due to formation of toxic hypochlorous acid (HOCl). However, the addition of physiological concentrations of thiocyanate protected the bacteria. Similarly, S. pneumoniae remained viable in the presence of lactoperoxidase and thiocyanate even though the majority of bacterial H₂O₂ was converted to hypothiocyanous acid (HOSCN). S. pneumoniae and Pseudomonas aeruginosa, another respiratory pathogen, were similarly sensitive to H₂O₂ and HOCl. In contrast, S. pneumoniae tolerated much higher doses of HOSCN than P. aeruginosa. When associated with neutrophil extracellular traps (NETs), S. pneumoniae continued to generate H₂O₂, which was converted to HOCl by MPO present on NETs. However, there was no loss in bacterial viability because HOCl was scavenged by the NET proteins. We conclude that at sites of infection, bacteria will be protected from HOCl by thiocyanate and extracellular proteins including those associated with NETs. Resistance to HOSCN may give S. pneumoniae a survival advantage over other pathogenic bacteria. Understanding the mechanisms by which S. pneumoniae protects itself from HOSCN may reveal novel strategies for limiting the colonization and pathogenicity of this deadly pathogen.

Optical detection of thiocyanate in human saliva based on the colorimetric response of (2-(2-hydroxyphenyl)-1H-benzo[d]imidazol-5-yl)(phenyl) methanone (HBPM)/Co2+ ions conjugate

Simple colorimetric biosensor was designed for the quantification SCN^- ions based on the principle of colorimetric reactions between Co²⁺ and SCN^- ions reaction using synthesized chromophore (2-(2-hydroxyphenyl)-1H-benzo[d]imidazol-5-yl)(phenyl) methanone (HBPM)/Co²⁺ ions conjugate which was synthesized via greener ultrawave sonication method. The structural characterization of the HBPM chromophore was confirmed by using NMR, ESI-MASS spectral techniques and the photophysical properties, sensor studies were done by using UV-Vis Spectrophotometer. Our designed HBPM/Co²⁺ ions conjugates have selectively detected SCN^- ions qualitatively and quantitatively in the presence of other human salivary interferents. As per clinical point of view, three different ranges of SCN^- ions from 0.1 to 2 mM for normal, 3 to 10 mM for disease, and 100-600 µM for below normal ranges were tested successfully by our developed sensor and the LoD was calculated as 5.43 nM. The real potent application of the developed biosensor was tested in human salivary samples of both smokers and non-smokers under different ages and obtained results shown good agreement with existing clinical methods.

Mucosal Immunity in Cystic Fibrosis

The highly complex and variable genotype-phenotype relationships observed in cystic fibrosis (CF) have been an area of growing interest since the discovery of the CF transmembrane conductance regulator (CFTR) gene >30 y ago. The consistently observed excessive, yet ineffective, activation of both the innate and adaptive host immune systems and the establishment of chronic infections within the lung, leading to destruction and functional decline, remain the primary causes of morbidity and mortality in CF. The fact that both inflammation and pathogenic bacteria persist despite the introduction of modulator therapies targeting the defective protein, CFTR, highlights that we still have much to discover regarding mucosal immunity determinants in CF. Gene modifier studies have overwhelmingly implicated immune genes in the pulmonary phenotype of the disease. In this context, we aim to review recent advances in our understanding of the innate and adaptive immune systems in CF lung disease.

Heme Peroxidases at Unperturbed and Inflamed Mucous Surfaces

In our organism, mucous surfaces are important boundaries against the environmental milieu with defined fluxes of metabolites through these surfaces and specific rules for defense reactions. Major mucous surfaces are formed by epithelia of the respiratory system and the digestive tract. The heme peroxidases lactoperoxidase (LPO), myeloperoxidase (MPO), and eosinophil peroxidase (EPO) contribute to immune protection at epithelial surfaces and in secretions. Whereas LPO is secreted from epithelial cells and maintains microbes in surface linings on low level, MPO and EPO are released from recruited neutrophils and eosinophils, respectively, at inflamed mucous surfaces. Activated heme peroxidases are able to oxidize (pseudo)halides to hypohalous acids and hypothiocyanite. These products are involved in the defense against pathogens, but can also contribute to cell and tissue damage under pathological conditions. This review highlights the beneficial and harmful functions of LPO, MPO, and EPO at unperturbed and inflamed mucous surfaces. Among the disorders, special attention is directed to cystic fibrosis and allergic reactions.

CFTR Protein: Not Just a Chloride Channel?

Cystic fibrosis (CF) is a recessive genetic disease caused by mutations in a gene encoding a protein called Cystic Fibrosis Transmembrane Conductance Regulator (CFTR). The CFTR protein is known to acts as a chloride (Cl-) channel expressed in the exocrine glands of several body systems where it also regulates other ion channels, including the epithelial sodium (Na+) channel (ENaC) that plays a key role in salt absorption. This function is crucial to the osmotic balance of the mucus and its viscosity. However, the pathophysiology of CF is more challenging than a mere dysregulation of epithelial ion transport, mainly resulting in impaired mucociliary clearance (MCC) with consecutive bronchiectasis and in exocrine pancreatic insufficiency. This review shows that the CFTR protein is not just a chloride channel. For a long time, research in CF has focused on abnormal Cl- and Na+ transport. Yet, the CFTR protein also regulates numerous other pathways, such as the transport of HCO3-, glutathione and thiocyanate, immune cells, and the metabolism of lipids. It influences the pH homeostasis of airway surface liquid and thus the MCC as well as innate immunity leading to chronic infection and inflammation, all of which are considered as key pathophysiological characteristics of CF.

Reverse Ordered Sequential Mechanism for Lactoperoxidase with Inhibition by Hydrogen Peroxide

Lactoperoxidase (LPO, Fe^III in its resting state in the absence of substrates)—an enzyme secreted from human mammary, salivary, and other mucosal glands—catalyzes the oxidation of thiocyanate (SCN⁻) by hydrogen peroxide (H₂O₂) to produce hypothiocyanite (OSCN⁻), which functions as an antimicrobial agent. The accepted catalytic mechanism, called the halogen cycle, comprises a two-electron oxidation of LPO by H₂O₂ to produce oxoiron(IV) radicals, followed by O-atom transfer to SCN⁻. However, the mechanism does not explain biphasic kinetics and inhibition by H₂O₂ at low concentration of reducing substrate, conditions that may be biologically relevant. We propose an ordered sequential mechanism in which the order of substrate binding is reversed, first SCN⁻ and then H₂O₂. The sequence of substrate binding that is described by the halogen cycle mechanism is actually inhibitory.

Association of exposures to perchlorate, nitrate, and thiocyanate with allergic symptoms: A population-based nationwide cohort study

Allergic diseases have been one of the leading causes of chronic disorders in the United States. Animal studies have suggested that exposures to perchlorate, nitrate, and thiocyanate could induce allergic inflammation. However, the associations have not been examined among general populations. Here, we investigated data of 7030 participants aged ≥6 years from the National Health and Nutritional Examination Survey (NHANES) 2005-2006. Urinary levels of perchlorate, nitrate, and thiocyanate were measured by ion chromatography combined with electrospray tandem mass spectrometry. Information on allergic symptoms (hay fever, allergy, rash, sneeze, wheeze, eczema, and current asthma) was collected by questionnaire. Allergic sensitization was defined by a concentration ≥150 kU/L for total immunoglobulin E (IgE) levels. The associations were estimated using multivariate-adjusted logistic regression models. A positive association was observed for urinary nitrate and eczema (p < 0.001 for the trend). Compared with quartile 1 (lowest quartile), the odds ratios of eczema with 95% confidence intervals [ORs (95% CIs)] from quartiles 2 to 4 were 1.72 (95% CI, 1.41, 2.09), 1.94 (1.53, 2.47) and 2.10 (1.49, 2.97) for urinary nitrate. In addition, urinary thiocyanate was positively related to sneeze (OR_{Q4 vs. Q1}: 1.25, 95% CI: 1.01, 1.55; p = 0.015 for the trend). However, urinary perchlorate was not correlated with any allergic-related outcome. Additionally, the associations were different among subgroups in a four-level polytomous model. Thus, our results suggested that exposures to nitrate and thiocyanate may be associated with allergic symptoms. Further investigations are warranted to concentrate on the practical strategies to monitor exposure levels and the latent mechanisms of the relationship between exposure and allergy.

Deletion of the lactoperoxidase gene causes multisystem inflammation and tumors in mice

Strongly oxidative H₂O₂ is biologically important, but if uncontrolled, would lead to tissue injuries. Lactoperoxidase (LPO) catalyzes the redox reaction of reducing highly reactive H₂O₂ to H₂O while oxidizing thiocyanate (SCN^-) to relatively tissue-innocuous hypothiocyanite (OSCN^-). SCN^- is the only known natural, effective reducing-substrate of LPO; humans normally derive SCN^- solely from food. While its enzymatic mechanism is understood, the actual biological role of the LPO-SCN^- system in mammals remains unestablished. Our group previously showed that this system protected cultured human cells from H₂O₂-caused injuries, a basis for the hypothesis that general deficiency of such an antioxidative mechanism would lead to multisystem inflammation and tumors. To test this hypothesis, we globally deleted the Lpo gene in mice. The mutant mice exhibited inflammation and lesions in the cardiovascular, respiratory, digestive or excretory systems, neuropathology, and tumors, with high incidence. Thus, this understudied LPO-SCN^- system is an essential protective mechanism in vivo.

A protet-based, protonic charge transfer model of energy coupling in oxidative and photosynthetic phosphorylation

Textbooks of biochemistry will explain that the otherwise endergonic reactions of ATP synthesis can be driven by the exergonic reactions of respiratory electron transport, and that these two half-reactions are catalyzed by protein complexes embedded in the same, closed membrane. These views are correct. The textbooks also state that, according to the chemiosmotic coupling hypothesis, a (or the) kinetically and thermodynamically competent intermediate linking the two half-reactions is the electrochemical difference of protons that is in equilibrium with that between the two bulk phases that the coupling membrane serves to separate. This gradient consists of a membrane potential term Δψ and a pH gradient term ΔpH, and is known colloquially as the protonmotive force or pmf. Artificial imposition of a pmf can drive phosphorylation, but only if the pmf exceeds some 150-170mV; to achieve in vivo rates the imposed pmf must reach 200mV. The key question then is 'does the pmf generated by electron transport exceed 200mV, or even 170mV?' The possibly surprising answer, from a great many kinds of experiment and sources of evidence, including direct measurements with microelectrodes, indicates it that it does not. Observable pH changes driven by electron transport are real, and they control various processes; however, compensating ion movements restrict the Δψ component to low values. A protet-based model, that I outline here, can account for all the necessary observations, including all of those inconsistent with chemiosmotic coupling, and provides for a variety of testable hypotheses by which it might be refined.

Modulation of hypochlorous acid (HOCl) induced damage to vascular smooth muscle cells by thiocyanate and selenium analogues

The production of hypochlorous acid (HOCl) by myeloperoxidase (MPO) plays a key role in immune defense, but also induces host tissue damage, particularly in chronic inflammatory pathologies, including atherosclerosis. This has sparked interest in the development of therapeutic approaches that decrease HOCl formation during chronic inflammation, including the use of alternative MPO substrates. Thiocyanate (SCN⁻) supplementation decreases HOCl production by favouring formation of hypothiocyanous acid (HOSCN), which is more selectively toxic to bacterial cells. Selenium-containing compounds are also attractive therapeutic agents as they react rapidly with HOCl and can be catalytically recycled. In this study, we examined the ability of SCN⁻, selenocyanate (SeCN⁻) and selenomethionine (SeMet) to modulate HOCl-induced damage to human coronary artery smooth muscle cells (HCASMC), which are critical to both normal vessel function and lesion formation in atherosclerosis. Addition of SCN⁻ prevented HOCl-induced cell death, altered the pattern and extent of intracellular thiol oxidation, and decreased perturbations to calcium homeostasis and pro-inflammatory signaling. Protection was also observed with SeCN⁻ and SeMet, though SeMet was less effective than SeCN⁻ and SCN⁻. Amelioration of damage was detected with sub-stoichiometric ratios of the added compound to HOCl. The effects of SCN⁻ are consistent with conversion of HOCl to HOSCN. Whilst SeCN⁻ prevented HOCl-induced damage to a similar extent to SCN⁻, the resulting product hyposelenocyanous acid (HOSeCN), was more toxic to HCASMC than HOSCN. These results provide support for the use of SCN⁻ and/or selenium analogues as scavengers, to decrease HOCl-induced cellular damage and HOCl production at inflammatory sites in atherosclerosis and other pathologies.

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HOCl induces extensive smooth muscle cell death and irreversible thiol oxidation.

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Addition of SCN⁻ decreases the extent of HOCl-induced cell damage.

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SeCN⁻ has similar protective effects to SCN⁻ towards HOCl-induced cell damage.

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HOSeCN is less toxic than HOCl but more damaging than HOSCN.

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SeMet modulates HOCl-induced damage but less effectively than SCN⁻ or SeCN⁻.

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.

Myeloperoxidase Modulates Hydrogen Peroxide Mediated Cellular Damage in Murine Macrophages

Myeloperoxidase (MPO) is involved in the development of many chronic inflammatory diseases, in addition to its key role in innate immune defenses. This is attributed to the excessive production of hypochlorous acid (HOCl) by MPO at inflammatory sites, which causes tissue damage. This has sparked wide interest in the development of therapeutic approaches to prevent HOCl-induced cellular damage including supplementation with thiocyanate (SCN^-) as an alternative substrate for MPO. In this study, we used an enzymatic system composed of glucose oxidase (GO), glucose, and MPO in the absence and presence of SCN^-, to investigate the effects of generating a continuous flux of oxidants on macrophage cell function. Our studies show the generation of hydrogen peroxide (H₂O₂) by glucose and GO results in a dose- and time-dependent decrease in metabolic activity and cell viability, and the activation of stress-related signaling pathways. Interestingly, these damaging effects were attenuated by the addition of MPO to form HOCl. Supplementation with SCN^-, which favors the formation of hypothiocyanous acid, could reverse this effect. Addition of MPO also resulted in upregulation of the antioxidant gene, NAD(P)H:quinone acceptor oxidoreductase 1. This study provides new insights into the role of MPO in the modulation of macrophage function, which may be relevant to inflammatory pathologies.

Myeloperoxidase: A versatile mediator of endothelial dysfunction and therapeutic target during cardiovascular disease

Myeloperoxidase (MPO) is a prominent mammalian heme peroxidase and a fundamental component of the innate immune response against microbial pathogens. In recent times, MPO has received considerable attention as a key oxidative enzyme capable of impairing the bioactivity of nitric oxide (NO) and promoting endothelial dysfunction; a clinically relevant event that manifests throughout the development of inflammatory cardiovascular disease. Increasing evidence indicates that during cardiovascular disease, MPO is released intravascularly by activated leukocytes resulting in its transport and sequestration within the vascular endothelium. At this site, MPO catalyzes various oxidative reactions that are capable of promoting vascular inflammation and impairing NO bioactivity and endothelial function. In particular, MPO catalyzes the production of the potent oxidant hypochlorous acid (HOCl) and the catalytic consumption of NO via the enzyme's NO oxidase activity. An emerging paradigm is the ability of MPO to also influence endothelial function via non-catalytic, cytokine-like activities. In this review article we discuss the implications of our increasing knowledge of the versatility of MPO's actions as a mediator of cardiovascular disease and endothelial dysfunction for the development of new pharmacological agents capable of effectively combating MPO's pathogenic activities. More specifically, we will (i) discuss the various transport mechanisms by which MPO accumulates into the endothelium of inflamed or diseased arteries, (ii) detail the clinical and basic scientific evidence identifying MPO as a significant cause of endothelial dysfunction and cardiovascular disease, (iii) provide an up-to-date coverage on the different oxidative mechanisms by which MPO can impair endothelial function during cardiovascular disease including an evaluation of the contributions of MPO-catalyzed HOCl production and NO oxidation, and (iv) outline the novel non-enzymatic mechanisms of MPO and their potential contribution to endothelial dysfunction. Finally, we deliver a detailed appraisal of the different pharmacological strategies available for targeting the catalytic and non-catalytic modes-of-action of MPO in order to protect against endothelial dysfunction in cardiovascular disease.

Development of a vaccine against Staphylococcus aureus invasive infections: Evidence based on human immunity, genetics and bacterial evasion mechanisms

Invasive Staphylococcus aureus infections are a leading cause of morbidity and mortality in both hospital and community settings, especially with the widespread emergence of virulent and multi-drug resistant methicillin-resistant S. aureus strains. There is an urgent and unmet clinical need for non-antibiotic immune-based approaches to treat these infections as the increasing antibiotic resistance is creating a serious threat to public health. However, all vaccination attempts aimed at preventing S. aureus invasive infections have failed in human trials, especially all vaccines aimed at generating high titers of opsonic antibodies against S. aureus surface antigens to facilitate antibody-mediated bacterial clearance. In this review, we summarize the data from humans regarding the immune responses that protect against invasive S. aureus infections as well as host genetic factors and bacterial evasion mechanisms, which are important to consider for the future development of effective and successful vaccines and immunotherapies against invasive S. aureus infections in humans. The evidence presented form the basis for a hypothesis that staphylococcal toxins (including superantigens and pore-forming toxins) are important virulence factors, and targeting the neutralization of these toxins are more likely to provide a therapeutic benefit in contrast to prior vaccine attempts to generate antibodies to facilitate opsonophagocytosis.

The Role of Thiocyanate in Modulating Myeloperoxidase Activity during Disease

Thiocyanate (SCN⁻) is a pseudohalide anion omnipresent across mammals and is particularly concentrated in secretions within the oral cavity, digestive tract and airway. Thiocyanate can outcompete chlorine anions and other halides (F⁻, Br⁻, I⁻) as substrates for myeloperoxidase by undergoing two-electron oxidation with hydrogen peroxide. This forms their respective hypohalous acids (HOX where X⁻ = halides) and in the case of thiocyanate, hypothiocyanous acid (HOSCN), which is also a bactericidal oxidative species involved in the regulation of commensal and pathogenic microflora. Disease may dysregulate redox processes and cause imbalances in the oxidative profile, where typically favoured oxidative species, such as hypochlorous acid (HOCl), result in an overabundance of chlorinated protein residues. As such, the pharmacological capacity of thiocyanate has been recently investigated for its ability to modulate myeloperoxidase activity for HOSCN, a less potent species relative to HOCl, although outcomes vary significantly across different disease models. To date, most studies have focused on therapeutic effects in respiratory and cardiovascular animal models. However, we note other conditions such as rheumatic arthritis where SCN⁻ administration may worsen patient outcomes. Here, we discuss the pathophysiological role of SCN⁻ in diseases where MPO is implicated.

Effects of Ammonium Chloride on Ozone-induced Airway Inflammation: the Role of Slc26a4 in the Lungs of Mice

BACKGROUND

Exposure to ozone (O₃) induces neutrophilic inflammation and goblet cell hyperplasia in humans and experimental animals. Because the solute carrier family 26-member 4 (Slc26a4; pendrin) gene induces mucin production and intraluminal acidification in the airways, it was hypothesized to be a key molecule in O₃-induced airway injury. Thus, we evaluated the role of Slc26a4 and the protective effects of ammonium chloride (NH₄Cl) in O₃-induced airway injury in mice.

METHODS

Six-week-old female BALB/c mice were exposed to filtered air or O₃ for 21 days (2 ppm for 3 hr/day). NH₄Cl (0, 0.1, 1, and 10 mM) was administered intratracheally into the airways. Airway resistance was measured using a flexiVent system, and bronchoalveolar lavage fluid (BALF) cells were differentially counted. Slc26a4 and Muc5ac proteins and mRNA were measured via western blotting, real-time polymerase chain reaction, and immunostaining. Tumor necrosis factor (TNF)-α, interferon (IFN)-γ, interleukin (IL)-17, IL-1β, and caspase-1 were analyzed via western blotting.

RESULTS

The levels Slc26a4 protein and mRNA significantly increased in lung tissues from Day 7 to Day 21 of O₃ exposure, with concomitant increases in lung resistance, numbers of goblet cells in lung tissues, and inflammatory cells and thiocyanate (SCN^-) levels in BALF in a time-dependent manner. Treatment with NH₄Cl significantly reduced these changes to levels similar to those of sham-treated mice, with a concomitant reduction of Slc26a4 proteins in lung lysates and SCN^- levels in BALF. Slc26a4 protein was co-expressed with muc5ac protein in the bronchial epithelium, as indicated by immunofluorescence staining. NH₄Cl treatment also significantly attenuated the O₃-induced increases in IFN-γ, TNF-α, IL-17, IL-1β, and p20-activated caspase-1.

CONCLUSION

Slc26a4 may be involved in O₃-induced inflammatory and epithelial changes in the airways via activation of the inflammasome and the induction of IL-17 and IFN-γ. NH₄Cl shows a potential as a therapeutic agent for controlling O₃-induced airway inflammation and epithelial damage by modulating Slc26a4 expression.

Role of thiocyanate in the modulation of myeloperoxidase-derived oxidant induced damage to macrophages

Myeloperoxidase (MPO) is a vital component of the innate immune system, which produces the potent oxidant hypochlorous acid (HOCl) to kill invading pathogens. However, an overproduction of HOCl during chronic inflammatory conditions causes damage to host cells, which promotes disease, including atherosclerosis. As such, there is increasing interest in the use of thiocyanate (SCN^-) therapeutically to decrease inflammatory disease, as SCN^- is the favoured substrate for MPO, and a potent competitive inhibitor of HOCl formation. Use of SCN^- by MPO forms hypothiocyanous acid (HOSCN), which can be less damaging to mammalian cells. In this study, we examined the ability of SCN^- to modulate damage to macrophages induced by HOCl, which is relevant to lesion formation in atherosclerosis. Addition of SCN^- prevented HOCl-mediated cell death, altered the extent and nature of thiol oxidation and the phosphorylation of mitogen activated protein kinases. These changes were dependent on the concentration of SCN^- and were observed in some cases, at a sub-stoichiometric ratio of SCN^-: HOCl. Co-treatment with SCN^- also modulated HOCl-induced perturbations in the expression of various antioxidant and inflammatory genes. In general, the data reflect the conversion of HOCl to HOSCN, which can induce reversible modifications that are repairable by cells. However, our data also highlight the ability of HOSCN to increase pro-inflammatory gene expression and cytokine/chemokine release, which may be relevant to the use of SCN^- therapeutically in atherosclerosis. Overall, this study provides further insight into the cellular pathways by which SCN^- could exert protective effects on supplementation to decrease the development of chronic inflammatory diseases, such as atherosclerosis.

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.

Meta-analysis Reveals Potential Influence of Oxidative Stress on the Airway Microbiomes of Cystic Fibrosis Patients

The lethal chronic airway infection of the cystic fibrosis (CF) patients is predisposed by colonization of specific CF-philic pathogens or the CF microbiomes, but key processes and reasons of the microbiome settlement in the patients are yet to be fully understood, especially their survival and metabolic dynamics from normal to diseased status under treatment. Here, we report our meta-analysis results on CF airway microbiomes based on metabolic networks reconstructed from genome information at species level. The microbiomes of CF patients appear to engage much more redox-related activities than those of controls, and by constructing a large dataset of anti-oxidative stress (anti-OS) genes, our quantitative evaluation of the anti-OS capacity of each bacterial species in the CF microbiomes confirms strong conservation of the anti-OS responses within genera and also shows that the CF pathogens have significantly higher anti-OS capacity than commensals and other typical respiratory pathogens. In addition, the anti-OS capacity of a relevant species correlates with its relative fitness for the airways of CF patients over that for the airways of controls. Moreover, the total anti-OS capacity of the respiratory microbiome of CF patients is collectively higher than that of controls, which increases with disease progression, especially after episodes of acute exacerbation and antibiotic treatment. According to these results, we propose that the increased OS in the airways of CF patients may play an important role in reshaping airway microbiomes to a more resistant status that favors the pre-infection colonization of the CF pathogens for a higher anti-OS capacity.

Theoretical Investigation of Cyano-Chalcogen Dimers and Their Importance in Molecular Recognition

In this manuscript the different noncovalent interactions established between (HYCN)₂ dimers (Y=S, Se and Te) have been studied at the MP2 and CCSD(T) level of theory. Several homodimers have been taken into account, highlighting the capacity of these compounds to act both as electron donor and acceptor. The main properties studied were geometries, binding energy (E_b ), and molecular electrostatic potential (MEP). Given the wide application of chalcogen bonds, and more specifically of cyano-chalcogen moieties in molecular recognition, natural bond orbital (NBO), "atoms-in-molecules" (AIM), and electron density shift (EDS) analysis were also used to analyse the different noncovalent interactions upon complexation. The presence of hydrogen, chalcogen and dipole-dipole interactions was confirmed and their implications on molecular recognition were analysed.

The role of endogenous bromotyrosine in health and disease

Bromotyrosine is a stable by-product of eosinophil peroxidase activity, a result of eosinophil activation during an inflammatory immune response. The elevated presence of bromotyrosine in tissue, blood, and urine in medical conditions involving eosinophil activation has highlighted the potential role of bromotyrosine as a medical biomarker. This is highly beneficial in a paediatric setting as a urinary noninvasive biomarker. However, bromotyrosine and its derivatives may exert biological effects, such as protective effects in the brain and pathogenic effects in the thyroid. Understanding these pathways may yield therapeutic advancements in medicine. In this review, we summarize the existing evidence present in literature relating to bromotyrosine formation and metabolism, identify the biological actions of bromotyrosine and evaluate the feasibility of bromotyrosine as a medical biomarker.

Red-Emitting Fluorescence Sensors for Metal Cations: The Role of Counteranions and Sensing of SCN- in Biological Materials

The spatiotemporal sensing of specific cationic and anionic species is crucial for understanding the processes occurring in living systems. Herein, we developed new fluorescence sensors derived from tetrapyrazinoporphyrazines (TPyzPzs) with a recognition moiety that consists of an aza-crown and supporting substituents. Their sensitivity and selectivity were compared by fluorescence titration experiments with the properties of known TPyzPzs (with either one aza-crown moiety or two of these moieties in a tweezer arrangement). Method of standard addition was employed for analyte quantification in saliva. For K⁺ recognition, the new derivatives had comparable or larger association constants with larger fluorescence enhancement factors compared to that with one aza-crown. Their fluorescence quantum yields in the ON state were 18× higher than that of TPyzPzs with a tweezer arrangement. Importantly, the sensitivity toward cations was strongly dependent on counteranions and increased as follows: NO₃^- < Br^- < CF₃SO₃^- < ClO₄^- ≪ SCN^-. This trend resembles the chaotropic ability expressed by the Hofmeister series. The high selectivity toward KSCN was explained by synergic association of both K⁺ and SCN^- with TPyzPz sensors. The sensing of SCN^- was further exploited in a proof of concept study to quantify SCN^- levels in the saliva of a smoker and to demonstrate the sensing ability of TPyzPzs under in vitro conditions.

Electrophysiological impact of thiocyanate on isolated mouse retinal pigment epithelial cells

Our recent electrophysiological analysis of mouse retinal pigment epithelial (RPE) cells revealed that in the presence of 10 mM external thiocyanate (SCN^-), voltage steps generated large transient currents whose time-dependent decay most likely results from the accumulation or depletion of SCN^- intracellularly. In the present study, we investigated the effects of more physiologically relevant concentrations of this biologically active anion. In whole cell recordings of C57BL/6J mouse RPE cells, we found that, over the range of 50 to 500 µM SCN^-, the amplitude of transient currents evoked by voltage steps was proportional to the extracellular SCN^- concentration. Transient currents were also produced in RPE cells when the membrane potential was held constant and the external SCN^- concentration was rapidly increased by pressure-ejecting 500 µM SCN^- from a second pipette. Other results indicate that the time dependence of currents produced by both approaches results from a change in driving force due to intracellular SCN^- accumulation or depletion. Finally, by applying fluorescence imaging and voltage-clamping techniques to BALB/c mouse RPE cells loaded with the anion-sensitive dye MQAE, we demonstrated that in the presence of 200 or 500 µM extracellular SCN^-, depolarizing voltage steps increased the cytoplasmic SCN^- concentration to an elevated steady state within several seconds. Collectively, these results indicate that, in the presence of physiological concentrations of SCN^- outside the RPE, the conductance and permeability of the RPE cell membranes for SCN^- are sufficiently large that SCN^- rapidly approaches electrochemical equilibrium within the cytoplasm when the membrane voltage or external SCN^- concentration is perturbed.

Oxidation of human plasma fibronectin by inflammatory oxidants perturbs endothelial cell function

Dysfunction of endothelial cells of the artery wall is an early event in cardiovascular disease and atherosclerosis. The cause(s) of this dysfunction are unresolved, but accumulating evidence suggests that oxidants arising from chronic low-grade inflammation are contributory agents, with increasing data implicating myeloperoxidase (MPO, released by activated leukocytes), and the oxidants it generates (e.g. HOCl and HOSCN). As these are formed extracellularly and react rapidly with proteins, we hypothesized that MPO-mediated damage to the matrix glycoprotein fibronectin (FN) would modulate FN structure and function, and its interactions with human coronary artery endothelial cells (HCAEC). Exposure of human plasma FN to HOCl resulted in modifications to FN and its functional epitopes. A dose-dependent loss of methionine and tryptophan residues, together with increasing concentrations of methionine sulfoxide, and modification of the cell-binding fragment (CBF) and heparin-binding fragment (HBF) domains was detected with HOCl, but not HOSCN. FN modification resulted in a loss of HCAEC adhesion, impaired cell spreading and reduced cell proliferation. Exposure to HCAEC to HOCl-treated FN altered the expression of HCAEC genes associated with extracellular matrix (ECM) synthesis and adhesion. Modifications were detected on HCAEC-derived ECM pre-treated with HOCl, but not HOSCN, with a loss of antibody recognition of the CBF, HBF and extra-domain A. Co-localization of epitopes arising from MPO-generated HOCl and cell-derived FN was detected in human atherosclerotic lesions. Damage was also detected on FN extracted from lesions. These data support the hypothesis that HOCl, but not HOSCN, targets and modifies FN resulting in arterial wall endothelial cell dysfunction.

Sorting out the Value of Cruciferous Sprouts as Sources of Bioactive Compounds for Nutrition and Health

Edible sprouts with germinating seeds of a few days of age are naturally rich in nutrients and other bioactive compounds. Among them, the cruciferous (Brassicaceae) sprouts stand out due to their high contents of glucosinolates (GLSs) and phenolic compounds. In order to obtain sprouts enriched in these phytochemicals, elicitation is being increasing used as a sustainable practice. Besides, the evidence regarding the bioavailability and the biological activity of these compounds after their dietary intake has also attracted growing interest in recent years, supporting the intake of the natural food instead of enriched ingredients or extracts. Also, there is a growing interest regarding their uses, consumption, and applications for health and wellbeing, in different industrial sectors. In this context, the present review aims to compile and update the available knowledge on the fundamental aspects of production, enrichment in composition, and the benefits upon consumption of diverse edible cruciferous sprouts, which are sources of phenolic compounds and glucosinolates, as well as the evidence on their biological actions in diverse pathophysiological situations and the molecular pathways involved.

Mouse retinal pigment epithelial cells exhibit a thiocyanate-selective conductance

The basolateral membrane anion conductance of the retinal pigment epithelium (RPE) is a key component of the transepithelial Cl^- transport pathway. Although multiple Cl^- channels have been found to be expressed in the RPE, the components of the resting Cl^- conductance have not been identified. In this study, we used the patch-clamp method to characterize the ion selectivity of the anion conductance in isolated mouse RPE cells and in excised patches of RPE basolateral and apical membranes. Relative permeabilities ( P_A/ P_Cl) calculated from reversal potentials measured in intact cells under bi-ionic conditions were as follows: SCN^- >> ClO₄^- > [Formula: see text] > I^- > Br^- > Cl^- >> gluconate. Relative conductances ( G_A/ G_Cl) followed a similar trend of SCN^- >> ClO₄^- > [Formula: see text] > I^- > Br^- ≈Cl^- >> gluconate. Whole cell currents were highly time-dependent in 10 mM external SCN^-, reflecting collapse of the electrochemical potential gradient due to SCN^- accumulation or depletion intracellularly. When the membrane potential was held at -120 mV to minimize SCN^- accumulation in cells exposed to 10 mM SCN^-, the instantaneous current reversed at -90 mV, revealing that P_SCN/ P_Cl is approximately 500. Macroscopic current recordings from outside-out patches demonstrated that both the basolateral and apical membranes exhibit SCN^- conductances, with the basolateral membrane having a larger SCN^- current density and higher relative permeability for SCN^-. Our results suggest that the RPE basolateral and apical membranes contain previously unappreciated anion channels or electrogenic transporters that may mediate the transmembrane fluxes of SCN^- and Cl^-.

Separation of Dual Oxidase 2 and Lactoperoxidase Expression in Intestinal Crypts and Species Differences May Limit Hydrogen Peroxide Scavenging During Mucosal Healing in Mice and Humans

BACKGROUND

DUOX2 and DUOXA2 form the predominant H2O2-producing system in human colorectal mucosa. Inflammation, hypoxia, and 5-aminosalicylic acid increase H2O2 production, supporting innate defense and mucosal healing. Thiocyanate reacts with H2O2 in the presence of lactoperoxidase (LPO) to form hypothiocyanate (OSCN-), which acts as a biocide and H2O2 scavenging system to reduce damage during inflammation. We aimed to discover the organization of Duox2, Duoxa2, and Lpo expression in colonic crypts of Lieberkühn (intestinal glands) of mice and how distributions respond to dextran sodium sulfate (DSS)-induced colitis and subsequent mucosal regeneration.

METHODS

We studied tissue from DSS-exposed mice and human biopsies using in situ hybridization, reverse transcription quantitative polymerase chain reaction, and cDNA microarray analysis.

RESULTS

Duox2 mRNA expression was mostly in the upper crypt quintile while Duoxa2 was more apically focused. Most Lpo mRNA was in the basal quintile, where stem cells reside. Duox2 and Duoxa2 mRNA were increased during the induction and resolution of DSS colitis, while Lpo expression did not increase during the acute phase. Patterns of Lpo expression differed from Duox2 in normal, inflamed, and regenerative mouse crypts (P < 0.001). We found no evidence of LPO expression in the human gut.

CONCLUSIONS

The spatial and temporal separation of H2O2-consuming and -producing enzymes enables a thiocyanate- H2O2 "scavenging" system in murine intestinal crypts to protect the stem/proliferative zones from DNA damage, while still supporting higher H2O2 concentrations apically to aid mucosal healing. The absence of LPO expression in the human gut suggests an alternative mechanism or less protection from DNA damage during H2O2-driven mucosal healing.

The hypothiocyanite radical OSCN and its isomers

An elusive biologically relevant hypothiocyanite radical (OSCN) has been generated in the gas phase, and its reversible photoisomerization with two novel isomers OSNC and SOCN has been observed in cryogenic Ar and N₂ matrices at 2.8 K.

Cystic fibrosis lung environment and Pseudomonas aeruginosa infection

Background

The airways of patients with cystic fibrosis (CF) are highly complex, subject to various environmental conditions as well as a distinct microbiota. Pseudomonas aeruginosa is recognized as one of the most important pulmonary pathogens and the predominant cause of morbidity and mortality in CF. A multifarious interplay between the host, pathogens, microbiota, and the environment shapes the course of the disease. There have been several excellent reviews detailing CF pathology, Pseudomonas and the role of environment in CF but only a few reviews connect these entities with regards to influence on the overall course of the disease. A holistic understanding of contributing factors is pertinent to inform new research and therapeutics.

Discussion

In this article, we discuss the deterministic alterations in lung physiology as a result of CF. We also revisit the impact of those changes on the microbiota, with special emphasis on P. aeruginosa and the influence of other non-genetic factors on CF. Substantial past and current research on various genetic and non-genetic aspects of cystic fibrosis has been reviewed to assess the effect of different factors on CF pulmonary infection. A thorough review of contributing factors in CF and the alterations in lung physiology indicate that CF lung infection is multi-factorial with no isolated cause that should be solely targeted to control disease progression. A combinatorial approach may be required to ensure better disease outcomes.

Conclusion

CF lung infection is a complex disease and requires a broad multidisciplinary approach to improve CF disease outcomes. A holistic understanding of the underlying mechanisms and non-genetic contributing factors in CF is central to development of new and targeted therapeutic strategies.