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Background: The upper respiratory tract (URT) is the portal of entry of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and SARS-CoV-2 likely interacts with the URT microbiome. However, understanding of the associations between the URT microbiome and the severity of coronavirus disease 2019 (COVID-19) is still limited. Objective: Our primary objective was to identify URT microbiome signature/s that consistently changed over a spectrum of COVID-19 severity. Methods: Using data from 103 adult participants from two cities in the United States, we compared the bacterial load and the URT microbiome between five groups: 20 asymptomatic SARS-CoV-2-negative participants, 27 participants with mild COVID-19, 28 participants with moderate COVID-19, 15 hospitalized patients with severe COVID-19, and 13 hospitalized patients in the ICU with very severe COVID-19. Results: URT bacterial load, bacterial richness, and within-group microbiome composition dissimilarity consistently increased as COVID-19 severity increased, while the relative abundance of an amplicon sequence variant (ASV), Corynebacterium _unclassified.ASV0002, consistently decreased as COVID-19 severity increased. Conclusions: We observed that the URT microbiome composition significantly changed as COVID-19 severity increased. The URT microbiome could potentially predict which patients may be more likely to progress to severe disease or be modified to decrease severity. However, further research in additional longitudinal cohorts is needed to better understand how the microbiome affects COVID-19 severity. [ABSTRACT FROM AUTHOR]

Background: Anosmia and ageusia are symptoms commonly associated with COVID-19, but the relationship with disease severity, onset and recovery are unclear. Objective: To examine factors associated with anosmia and ageusia and the recovery from these symptoms in an ethnically diverse cohort. Methods: Individuals tested for SARS-CoV-2 between March and April 2020 were eligible for the study. Randomly selected participants answered a telephone questionnaire on COVID-19 symptoms with a focus on anosmia and ageusia. Additionally, relevant past medical history and data on the COVID-19 clinical course were obtained from electronic medical records. 486 patients were in the COVID-19 group and 103 were COVID-19-negative. Results: Patients who were younger were more likely to report anosmia and/or ageusia (odds ratio (OR) for anosmia per 1-year increase in age: 0·98, 95%CI:0–97-0·99, p = 0·003; for ageusia: 0·98, 95%CI:0·97-0·99, p = 0·005) as were patients with lower eosinophil counts (OR for anosmia per 0.1-K/μL increase in eosinophils: 0·02, 95%CI:0·001-0·46, p = 0·01, for ageusia 0·10, 95%CI:0·01-0·97, p = 0·047). Male gender was independently associated with a lower probability of ageusia (OR:0·56, 95%CI:0·38-0·82, p = 0·003) and earlier sense of taste recovery (HR:1·44, 95%CI:1·05-1·98, p = 0·02). Latinos showed earlier sense of taste recovery than white patients (HR:1·82, 95%CI:1·05-3·18, p = 0·03). Conclusion: Anosmia and ageusia were more common among younger patients and those with lower blood eosinophil counts. Ageusia was less commonly reported among men, and time to taste recovery was earlier among both men and Latinos. [ABSTRACT FROM AUTHOR]

Non-steroidal Anti-inflammatory drugs (NSAID)-exacerbated respiratory disease (N-ERD) is characterized by nasal polyposis, chronic rhinosinusitis, adult-onset asthma and hypersensitive reactions to cyclooxygenase-1 (COX-1) inhibitors. Among the available treatments for this disease, a combination of endoscopic sinus surgery followed by aspirin desensitization and aspirin maintenance therapy has been an effective approach. Studies have shown that long-term aspirin maintenance therapy can reduce the rate of nasal polyp recurrence in patients with N-ERD. However, the exact mechanism by which aspirin can both trigger and suppress airway disease in N-ERD remains poorly understood. In this review, we summarize current knowledge of aspirin effects in N-ERD, cardiovascular disease, and cancer, and consider potential mechanistic pathways accounting for the effects of aspirin in N-ERD. [ABSTRACT FROM AUTHOR]

Conversely, tissue neutrophil association with LM scores in N-ERD patients suggests that neutrophils contribute to the severity of the polyp burden in N-ERD. Neutrophilic inflammation and epithelial barrier disruption in nasal polyps characterize non-steroidal anti-inflammatory drug exacerbated respiratory disease Neutrophil counts were higher in the nasal polyp tissues of N-ERD patients (8.5 cells per hpf (IQR 3-25) vs. 2.5 cells (IQR 2-5) in non-N-ERD ( I p i = .026, Figure 1B). [Extracted from the article]

GoxA is a glycine oxidase that possesses a cysteine tryptophylquinone (CTQ) cofactor that is formed by posttranslational modifications that are catalyzed by a modifying enzyme GoxB. It is the second known tryptophylquinone enzyme to function as an oxidase, the other being the lysine -oxidase, LodA. All other enzymes containing CTQ or tryptophan tryptophylquinone (TTQ) cofactors are dehydrogenases. Kinetic analysis of GoxA revealed allosteric cooperativity for its glycine substrate, but not O2. This is the first CTQ- or TTQ-dependent enzyme to exhibit cooperativity. Here, we show that cooperativity and homodimer stabilization are strongly dependent on the presence of Phe-237. Conversion of this residue, which is a Tyr in LodA, to Tyr or Ala eliminates the cooperativity and destabilizes the dimer. These mutations also significantly affect the kcat and Km values for the substrates. On the basis of structural and modeling studies, a mechanism by which Phe-237 exerts this influence is presented. Two active site residues, Asp-547 and His-466, were also examined and shown by site-directed mutagenesis to be critical for CTQbiogenesis. This result is compared with the results of similar studies of mutagenesis of structurally conserved residues of other tryptophylquinone enzymes. These results provide insight into the roles of specific active-site residues in catalysis and CTQ biogenesis, as well as describing an interesting mechanism by which a single residue can dictate whether or not an enzyme exhibits cooperative allosteric behavior toward a substrate. [ABSTRACT FROM AUTHOR]

GoxA is a glycine oxidase bearing a protein-derived cysteine tryptophylquinone (CTQ) cofactor that is formed by posttranslational modifications catalyzed by a flavoprotein, GoxB. Two forms of GoxA were isolated: an active form with mature CTQ and an inactive precursor protein that lacked CTQ. The active GoxA was present as a homodimer with no detectable affinity for GoxB, whereas the precursor was isolated as a monomer in a tight complex with one GoxB. Thus, the interaction of GoxA with GoxB and subunit assembly of mature GoxA are each dependent on the extent of CTQ biosynthesis. [ABSTRACT FROM AUTHOR]

Site-directed mutagenesis identified residues in the substrate channel of LodA that play multiple roles in regulating K m values of substrates, k cat and the extent of biosynthesis of the protein-derived cysteine tryptophylquinone (CTQ) cofactor. Mutations of Cys448 increase K m values for lysine and O 2 , with the larger effect on K lysine . Tyr211 resides within a mobile loop and is seen in the crystal structure of LodA to form a hydrogen bond with Lys530 that appears to stabilize its position in the channel. Y211F LodA had reduced levels of CTQ but near normal levels of k cat . K530A and K530R variants exhibited diminished levels of CTQ but significantly increased k cat . The Y211F, K530A and K530R mutations each caused large increases in the K m values for lysine and O 2 . These effects of the mutations of Tyr211 and Lys530 suggest that when these residues are hydrogen-bonded they may form a gate that controls entry and exit of substrates and products from the active site. Y211A and Y211E variants had the highest level of CTQ but exhibited no activity. These results highlight the different evolutionary factors that must be considered for enzymes which possess protein-derived cofactors, in which the catalytic cofactor must be generated by posttranslational modifications. [ABSTRACT FROM AUTHOR]

Highlights: [•] LodA has a tryptophylquinone cofactor but functions as an oxidase not a dehydrogenase. [•] LodA exhibits a ping-pong kinetic mechanism with lysine and O2 as substrates. [•] The kinetic mechanism of LodA is consistent with a covalent lysine-CTQ intermediate. [ABSTRACT FROM AUTHOR]

The Rv2633c gene in Mycobacterium tuberculosis is rapidly up-regulated after macrophage infection, suggesting that Rv2633c is involved in M. tuberculosis pathogenesis. However, the activity and role of the Rv2633c protein in host colonization is unknown. Here, we analyzed the Rv2633c protein sequence, which revealed the presence of an HHE cation-binding domain common in hemerythrin-like proteins. Phylogenetic analysis indicated that Rv2633c is a member of a distinct subset of hemerythrin-like proteins exclusive to mycobacteria. The Rv2633c sequence was significantly similar to protein sequences from other pathogenic strains within that subset, suggesting that these proteins are involved in mycobacteria virulence. We expressed and purified the Rv2633c protein in Escherichia coli and found that it contains two iron atoms, but does not behave like a hemerythrin. It migrated as a dimeric protein during size-exclusion chromatography. It was not possible to reduce the protein or observe any evidence for its interaction with O2. However, Rv2633c did exhibit catalase activity with a kcat of 1475 s-1 and Km of 10.1 ± 1.7 mM. Cyanide and azide inhibited the catalase activity with Ki values of 3.8 μM and 37.7 μM, respectively. Rv2633c's activity was consistent with a role in defenses against oxidative stress generated during host immune responses after M. tuberculosis infection of macrophages. We note that Rv2633c is the first example of a non-heme di-iron catalase, and conclude that it is a member of a subset of hemerythrin-like proteins exclusive to mycobacteria, with likely roles in protection against host defenses. [ABSTRACT FROM AUTHOR]

Background: mAbs (biologics) are indicated in patients with poorly controlled moderate-to-severe asthma. The process of prior authorization and administration of a biologic requires exceptional commitment from clinical teams., Objective: Our aim was to evaluate the process of approval and administration of biologics for asthma and determine the most common reasons associated with denials of biologics and delays in administration., Methods: We examined the records of patients with asthma who were prescribed biologics from January 2018 to January 2020 at 2 centers, Montefiore Medical Center (Bronx, NY) and Scripps Clinics (San Diego, Calif). Demographics, insurance information, and details on the approval process were collected., Results: After querying of electronic health records, the records of 352 and 70 patients with moderate-to-severe asthma were included from Montefiore and Scripps, respectively. Most patients at Montefiore (58.2%) were insured under Managed Care Medicaid (MC Medicaid), whereas most patients at Scripps (61.4%) had commercial insurance. The median times from prescription to administration of a biologic were similar: 34 days (interquartile range [IQR] = 18-63 days) and 34 days (IQR = 22.5-56.0 days) ( P  = .97) for Montefiore and Scripps, respectively. However, the median approval time for Montefiore was 6 days (IQR = 1-20 days) and that for Scripps was 22 days (IQR = 10-36 days) ( P  < .001). Approval times for prescriptions requiring appeals were significantly longer than for prescriptions approved after the initial submission: 23 days versus 2.5 days and 40.5 days versus 15.5 days (for Montefiore and Scripps, respectively [ P  < .001 for both])., Conclusions: Lengthy appeals contribute to delays between prescribing and administering a biologic. Site-specific practices and insurance coverage influence approval timing of the biologics for asthma., (© 2023 The Author(s).)

Nonsteroidal anti-inflammatory drug (NSAID)-exacerbated respiratory disease (N-ERD) is characterized by nasal polyp formation, adult-onset asthma, and hypersensitivity to all cyclooxygenase-1 (COX-1) inhibitors. Oxygenated lipids are collectively known as oxylipins and are polyunsaturated fatty acids (PUFA) oxidation products. The most extensively researched oxylipins being the eicosanoids formed from arachidonic acid (AA). There are four major classes of eicosanoids including leukotrienes, prostaglandins, thromboxanes, and lipoxins. In N-ERD, the underlying inflammatory process of the upper and lower respiratory systems begins and occurs independently of NSAID consumption and is due to the overproduction of cysteinyl leukotrienes. Leukotriene mediators all induce edema, bronchoconstriction, and airway mucous secretion. Thromboxane A 2 is a potent bronchoconstrictor and induces endothelial adhesion molecule expression. Elevated Prostaglandin D 2 metabolites lead to vasoconstriction, additionally impaired up-regulation of prostaglandin E 2 leads to symptoms seen in N-ERD as it is essential for maintaining homeostasis of inflammatory responses in the airway and has bronchoprotective and anti-inflammatory effects. A characteristic feature of N-ERD is diminished lipoxin levels, this decreased capacity to form endogenous mediators with anti-inflammatory properties could facilitate local inflammatory response and expose bronchial smooth muscle to relatively unopposed actions of broncho-constricting substances. Treatment options, such as leukotriene modifying agents, aspirin desensitization, biologic agents and ESS, appear to influence eicosanoid pathways, however more studies need to be done to further understand the role of oxylipins. Besides AA-derived eicosanoids, other oxylipins may also pay a role but have not been sufficiently studied. Identifying pathogenic N-ERD mechanism is likely to define more effective treatment targets., Competing Interests: Conflict of interest Elina Jerschow: Advisory Board—GlaxoSmithKline, Regeneron/Sanofi. Consultant—GlaxoSmithKline. AstraZeneca, Regeneron. Research grants: AstraZeneca, Regeneron., (Copyright © 2023 Elsevier Inc. All rights reserved.)

The Rv2633c gene in Mycobacterium tuberculosis is rapidly up-regulated after macrophage infection, suggesting that Rv2633c is involved in M. tuberculosis pathogenesis. However, the activity and role of the Rv2633c protein in host colonization is unknown. Here, we analyzed the Rv2633c protein sequence, which revealed the presence of an HHE cation-binding domain common in hemerythrin-like proteins. Phylogenetic analysis indicated that Rv2633c is a member of a distinct subset of hemerythrin-like proteins exclusive to mycobacteria. The Rv2633c sequence was significantly similar to protein sequences from other pathogenic strains within that subset, suggesting that these proteins are involved in mycobacteria virulence. We expressed and purified the Rv2633c protein in Escherichia coli and found that it contains two iron atoms, but does not behave like a hemerythrin. It migrated as a dimeric protein during size-exclusion chromatography. It was not possible to reduce the protein or observe any evidence for its interaction with O 2 However, Rv2633c did exhibit catalase activity with a k cat of 1475 s -1 and K m of 10.1 ± 1.7 mm Cyanide and azide inhibited the catalase activity with K i values of 3.8 μm and 37.7 μm, respectively. Rv2633c's activity was consistent with a role in defenses against oxidative stress generated during host immune responses after M. tuberculosis infection of macrophages. We note that Rv2633c is the first example of a non-heme di-iron catalase, and conclude that it is a member of a subset of hemerythrin-like proteins exclusive to mycobacteria, with likely roles in protection against host defenses., (© 2018 by The American Society for Biochemistry and Molecular Biology, Inc.)

When performing site-directed mutagenesis experiments to study protein structure-function relationships, ideally one would know the structure of the protein under study. It is also very useful to have structures of multiple related proteins in order to determine whether or not particular amino acid residues are conserved in the structures either in the active site of an enzyme at the surface of a protein or at a putative protein-protein interface. While many protein structures are available in the Protein Data Base (PDB), a structure of the protein of interest may not be available. In the study of reversible and often transient protein-protein interactions it is rare to have a structure of the complex of the two interacting proteins. In this chapter, methods are described for comparing protein structures, generating putative structures of proteins with homology models based on the protein primary sequence, and generating docking models to predict interaction sites between proteins and cofactor-protein interactions. The rationale used to predict mutagenesis targets from these structures and models is also described.

To completely understand the role of an amino acid residue that is targeted for site-directed mutagenesis a thorough analysis of the impact that the mutation has on the function of the protein is required. General methods for performing site-directed mutagenesis and expressing the recombinant protein variant are described. Protein-cofactor interactions are important because cofactors are often directly involved in facilitating catalysis by enzymes and in electron transfer by redox proteins. Many cofactors also have characteristic spectroscopic properties. As such, general methods are described to analyze the spectroscopic, redox and catalytic properties of protein-bound cofactors. Methods for assessing the effects of a mutation on protein-protein interactions are also described. Lastly, methods for assessing the overall structural integrity of the protein are described, as this is important to ensure that the mutation has not caused a global disruption of protein structure, rather than a specific effect on function.