A halotyrosine antibody that detects increased protein modifications in asthma patients

Reactive Halogen Species: Role in Living Systems and Current Research Approaches

Reactive halogen species (RHS) are highly reactive compounds that are normally required for regulation of immune response, inflammatory reactions, enzyme function, etc. At the same time, hyperproduction of highly reactive compounds leads to the development of various socially significant diseases - asthma, pulmonary hypertension, oncological and neurodegenerative diseases, retinopathy, and many others. The main sources of (pseudo)hypohalous acids are enzymes from the family of heme peroxidases - myeloperoxidase, lactoperoxidase, eosinophil peroxidase, and thyroid peroxidase. Main targets of these compounds are proteins and peptides, primarily methionine and cysteine residues. Due to the short lifetime, detection of RHS can be difficult. The most common approach is detection of myeloperoxidase, which is thought to reflect the amount of RHS produced, but these methods are indirect, and the results are often contradictory. The most promising approaches seem to be those that provide direct registration of highly reactive compounds themselves or products of their interaction with components of living cells, such as fluorescent dyes. However, even such methods have a number of limitations and can often be applied mainly for in vitro studies with cell culture. Detection of reactive halogen species in living organisms in real time is a particularly acute issue. The present review is devoted to RHS, their characteristics, chemical properties, peculiarities of interaction with components of living cells, and methods of their detection in living systems. Special attention is paid to the genetically encoded tools, which have been introduced recently and allow avoiding a number of difficulties when working with living systems.

Mineral Micronutrients in Asthma

Asthma represents one of the most common medical issues in the modern world. It is a chronic inflammatory disease characterized by persistent inflammation of the airways and disturbances in redox status, leading to hyperresponsiveness of bronchi and airway obstruction. Apart from classical risk factors such as air pollution, family history, allergies, or obesity, disturbances of the levels of micronutrients lead to impairments in the defense mechanisms of the affected organism against oxidative stress and proinflammatory stimuli. In the present review, the impact of micronutrients on the prevalence, severity, and possible risk factors of asthma is discussed. Although the influence of classical micronutrients such as selenium, copper, or zinc are well known, the effects of those such as iodine or manganese are only rarely mentioned. As a consequence, the aim of this paper is to demonstrate how disturbances in the levels of micronutrients and their supplementation might affect the course of asthma.

Quantitative immunohistochemistry (IHC) analysis of biomarker combinations for human esophageal squamous cell carcinoma

Background

Esophageal squamous carcinoma (ESCC) is one of the most common cancers in developing countries. However, currently there are no specific biomarkers for ESCC. This study evaluated the expression of proliferating cell nuclear antigen (PCNA), tumor suppressor protein p53, epidermal growth factor receptor (EGFR), and vascular endothelial growth factor (VEGF) as biomarkers for ESCC.

Methods

This study included 60 clinical cases (30 ESCC and 30 non-ESCC cases that were confirmed pathologically). The expression of PCNA, p53, EGFR, and VEGF were investigated using a quantitative computerized immunohistochemistry (IHC) method. The expression level of each protein was indicated by a H-score from the quantitative analysis. Receiver operating characteristic curve (ROC) and area under curve (AUC) analyses were performed. The sensitivity and specificity of each individual protein and combinations of the proteins were calculated.

Results

The H-score analysis indicated that expressions of EGFR, PCNA, and VEGF were statistically significantly higher in ESCC than non-ESCC patients; however, p53 was not. The panels of combinations of these proteins were more sensitive than that of any single protein. In the triplicate combination, the AUC prediction probability increased to 0.86, while the single protein AUC prediction probabilities were 0.74 (EGFR), 0.80 (PCNA), and 0.70 (VEGF).

Conclusions

The high expression of PCNA, EGFR, and VEGF suggests that they are potential biomarkers for ESCC. The combination of these biomarkers may provide targets for molecular therapy and molecular imaging.

Underestimation of airway luminal eosinophilia by quantitative sputum cytometry

RATIONALE

On Wright-stained sputum cytospins, eosinophil differential of ≥ 1.2% is considered abnormal, and ≥ 2.3% identifies an eosinophilic endotype. We hypothesized that failure to consider free eosinophil granules (FEG), and the re-emergence (unmasking) of eosinophilia due to various reasons underestimate the prevalence of the eosinophilic endotype.

METHODS

This is a retrospective analysis of our Institutional Review Board-approved clinical sputum database. Of the 24,176 examinations of sputa from patients with various airway diseases, 17,693 were viable cell counts from 9570 patients (6604 on a single occasion, 2967 from multiple occasions). The prevalence of intact eosinophil % at 1.2 and 2.3% thresholds was first examined. Then, additional evidence of eosinophilia was assessed by semi-quantitative enumeration of FEGs. In those patients whose sputa were examined on multiple occasions (at the time of an exacerbation or after corticosteroid dose was reduced), re-emergence (unmasking) of eosinophilia was assessed .

RESULTS

Using the threshold of eosinophilia ≥ 1.2%, 6289/17693 (35.6%) of sputa were classified as eosinophilic. This increased to 7850/17693 (44.4%) when the presence of FEGs was considered. Using the threshold of eosinophilia ≥ 2.3%, 4647/17693 (26.3%) of sputa were classified as eosinophilic. This increased to 5435/17693 (30.7%) when the presence of FEG were considered. Extrapolating from the prevalence of re-emergence observed in the 2967 patients who had sputa examined on multiple occasions to the whole sample, we estimated that eosinophilia at 1.2% threshold would be observed in at least 60% of the samples, and a clinically relevant eosinophilia at 2.3% threshold would be observed in at least 48.5% of the samples.

CONCLUSIONS

Using a large sputum cytometry clinical database (17,693 viable cell counts), we demonstrate that a single time point intact cell count underestimates the prevalence of eosinophilia in a variety of airway diseases. The prevalence of eosinophilia increases from 35.6 to 60% (40% underestimation) at the 1.2% threshold, and from 26.3 to 48.5% (45% underestimation) at the 2.3% clinically relevant threshold, when free granules and a second examination are considered. This has important implications to identify the eosinophilic and Th2 high endotype both for clinical trials of anti-eosinophil therapies, and to select patients who may respond well to glucocorticosteroids and anti-IL5 therapies.

Labeling of Peroxide-Induced Oxidative Stress Hotspots by Hemin-Catalyzed Tyrosine Click

Tyrosyl radical generation is one of the major factors for hemin/peroxide-induced oxidative stress. A method for trapping tyrosyl radical directly was developed using N-methyl luminol derivative, a tyrosine labeling reagent. N-Methyl luminol derivative selectively forms a covalent bond with a tyrosine residue under the single-electron oxidation condition. This reaction labels oxidative stress hotspots not only at the protein level but also at the level of tyrosine residues undergoing oxidation. Human serum albumin complexed with hemin was labeled at Tyr138, the tyrosine residue closest to the hemin binding site and most strongly subjected to oxidative stress caused by hemin/H₂O₂. Oxidatively damaged proteins were visualized in protein mixtures.

Structure and composition of the tunic in the sea pineapple Halocynthia roretzi: A complex cellulosic composite biomaterial

Biological organisms produce high-performance composite materials, such as bone, wood and insect cuticle, which provide inspiration for the design of novel materials. Ascidians (sea squirts) produce an organic exoskeleton, known as a tunic, which has been studied quite extensively in several species. However, currently, there are still gaps in our knowledge about the detailed structure and composition of this cellulosic biocomposite. Here, we investigate the composition and hierarchical structure of the tough tunic from the species Halocynthia roretzi, through a cross-disciplinary approach combining traditional histology, immunohistochemistry, vibrational spectroscopy, X-ray diffraction, and atomic force and electron microscopies. The picture emerging is that the tunic of H. roretzi is a hierarchically-structured composite of cellulose and proteins with several compositionally and structurally distinct zones. At the surface is a thin sclerotized cuticular layer with elevated composition of protein containing halogenated amino acids and cross-linked via dityrosine linkages. The fibrous layer makes up the bulk of the tunic and is comprised primarily of helicoidally-ordered crystalline cellulose fibres with a lower protein content. The subcuticular zone directly beneath the surface contains much less organized cellulose fibres. Given current efforts to utilize biorenewable cellulose sources for the sustainable production of bio-inspired composites, these insights establish the tunic of H. roretzi as an exciting new archetype for extracting relevant design principles. STATEMENT OF SIGNIFICANCE: Tunicates are the only animals able to produce cellulose. They use this structural polysaccharide to build an exoskeleton called a tunic. Here, we investigate the composition and hierarchical structure of the tough tunic from the sea pineapple Halocynthia roretzi through a multiscale cross-disciplinary approach. The tunic of this species is a composite of cellulose and proteins with two distinct layers. At the surface is a thin sclerotized cuticular layer with a higher protein content containing halogenated amino acids and cross-linked via dityrosine linkages. The fibrous layer makes up the bulk of the tunic and is comprised of well-ordered cellulose fibres with a lower protein content. Given current efforts to utilize cellulose to produce advanced materials, the tunic of the sea pineapple provides a striking model for the design of bio-inspired cellulosic composites.

Efficient Site-Specific Prokaryotic and Eukaryotic Incorporation of Halotyrosine Amino Acids into Proteins

Post-translational modifications (PTMs) of protein tyrosine (Tyr) residues can serve as a molecular fingerprint of exposure to distinct oxidative pathways and are observed in abnormally high abundance in the majority of human inflammatory pathologies. Reactive oxidants generated during inflammation include hypohalous acids and nitric oxide-derived oxidants, which oxidatively modify protein Tyr residues via halogenation and nitration, respectively, forming 3-chloroTyr, 3-bromoTyr, and 3-nitroTyr. Traditional methods for generating oxidized or halogenated proteins involve nonspecific chemical reactions that result in complex protein mixtures, making it difficult to ascribe observed functional changes to a site-specific PTM or to generate antibodies sensitive to site-specific oxidative PTMs. To overcome these challenges, we generated a system to efficiently and site-specifically incorporate chloroTyr, bromoTyr, and iodoTyr, and to a lesser extent nitroTyr, into proteins in both bacterial and eukaryotic expression systems, relying on a novel amber stop codon-suppressing mutant synthetase (haloTyrRS)/tRNA pair derived from the Methanosarcina barkeri pyrrolysine synthetase system. We used this system to study the effects of oxidation on HDL-associated protein paraoxonase 1 (PON1), an enzyme with important antiatherosclerosis and antioxidant functions. PON1 forms a ternary complex with HDL and myeloperoxidase (MPO) in vivo. MPO oxidizes PON1 at tyrosine 71 (Tyr71), resulting in a loss of PON1 enzymatic function, but the extent to which chlorination or nitration of Tyr71 contributes to this loss of activity is unclear. To better understand this biological process and to demonstrate the utility of our GCE system, we generated PON1 site-specifically modified at Tyr71 with chloroTyr and nitroTyr in Escherichia coli and mammalian cells. We demonstrate that either chlorination or nitration of Tyr71 significantly reduces PON1 enzymatic activity. This tool for site-specific incorporation of halotyrosine will be critical to understanding how exposure of proteins to hypohalous acids at sites of inflammation alters protein function and cellular physiology. In addition, it will serve as a powerful tool for generating antibodies that can recognize site-specific oxidative PTMs.

Mechanisms and Biomarkers of Exercise-Induced Bronchoconstriction

Exercise is a common trigger of bronchoconstriction. In recent years, there has been increased understanding of the pathophysiology of exercise-induced bronchoconstriction. Although evaporative water loss and thermal changes have been recognized stimuli for exercise-induced bronchoconstriction, accumulating evidence points toward a pivotal role for the airway epithelium in orchestrating the inflammatory response linked to exercise-induced bronchoconstriction. Overproduction of inflammatory mediators, underproduction of protective lipid mediators, and infiltration of the airways with eosinophils and mast cells are all established contributors to exercise-induced bronchoconstriction. Sensory nerve activation and release of neuropeptides maybe important in exercise-induced bronchoconstriction, but further research is warranted.

Chlorinated Phospholipids and Fatty Acids: (Patho)physiological Relevance, Potential Toxicity, and Analysis of Lipid Chlorohydrins

Chlorinated phospholipids are formed by the reaction of hypochlorous acid (HOCl), generated by the enzyme myeloperoxidase under inflammatory conditions, and the unsaturated fatty acyl residues or the head group. In the first case the generated chlorohydrins are both proinflammatory and cytotoxic, thus having a significant impact on the structures of biomembranes. The latter case leads to chloramines, the properties of which are by far less well understood. Since HOCl is also widely used as a disinfecting and antibacterial agent in medicinal, industrial, and domestic applications, it may represent an additional source of danger in the case of abuse or mishandling. This review discusses the reaction behavior of in vivo generated HOCl and biomolecules like DNA, proteins, and carbohydrates but will focus on phospholipids. Not only the beneficial and pathological (toxic) effects of chlorinated lipids but also the importance of these chlorinated species is discussed. Some selected cleavage products of (chlorinated) phospholipids and plasmalogens such as lysophospholipids, (chlorinated) free fatty acids and α-chloro fatty aldehydes, which are all well known to massively contribute to inflammatory diseases associated with oxidative stress, will be also discussed. Finally, common analytical methods to study these compounds will be reviewed with focus on mass spectrometric techniques.