Inhaled therapies for chronic obstructive pulmonary disease: a systematic review and meta-analysis.

OBJECTIVES: To integrate evidence from randomised controlled trials (RCTs) and observational studies on the efficacy of inhaled treatments for chronic obstructive pulmonary disease using network meta-analyses. METHODS: Systematic searches MEDLINE and Embase based on predetermined criteria. Network meta-analyses of RCTs investigated efficacy on exacerbations (long-term: ≥20 weeks of treatment; short-term: <20 weeks), lung function (≥12 weeks), health-related quality of life, mortality and adverse events. Qualitative comparisons of efficacies between RCTs and observational studies. RESULTS: 212 RCTs and 19 observational studies were included. Compared with combined long-acting beta-adrenoceptor agonists and long-acting muscarinic antagonists (LABA+LAMA), triple therapy (LABA+LAMA+inhaled corticosteroid) was significantly more effective at reducing exacerbations (long-term 0.85 (95% CI: 0.78 to 0.94; short-term 0.67 (95% CI: 0.49 to 0.92)) and mortality (0.72 (95% CI: 0.59 to 0.89)) but was also associated with increased pneumonia (1.35 (95% CI: 1.10 to 1.67)). No differences in lung function (0.02 (95% CI: -0.10 to 0.14)), health-related quality of life (-1.12 (95% CI: -3.83 to 1.59)) or other adverse events (1.02 (95% CI: 0.96 to 1.08)) were found. Most of the observational evidence trended in the same direction as pooled RCT data. CONCLUSION: Further evidence, especially pragmatic trials, are needed to fully understand the characteristics of patient subgroups who may benefit from triple therapy and for those whom the extra risk of adverse events, such as pneumonia, may outweigh any benefits. PROSPERO REGISTRATION NUMBER: CRD42018088013.

Real-life prescribing of asthmatic treatments in UK general practice over time using 2014 BTS/SIGN steps.

The 2014 British Thoracic Society (BTS) and Scottish Intercollegiate Guideline Network (SIGN) guidelines recommend a stepwise approach to asthma management. We investigated the management of asthma in primary care in the UK to understand how real-world practice compares with BTS/SIGN guidelines. Asthma patients were identified from the UK Clinical Practice Research Datalink from September 2006 to August 2016. Aims were to classify patients according to BTS/SIGN steps, describe the proportion of patients transitioning between steps and describe patient demographics and clinical characteristics per group. Overall, 647,308 patients with asthma were identified (40,096 aged 5-11 years; 607,212 aged 12-80 years). Most treated patients were in step 1 or 2 (88.3% of children/67.5% of adults in December 2007; 83.0% of children/67.0% of adults in June 2016). Most patients remained within their treatment step within a 6-month interval (>78% of children and adults throughout the study duration). The proportion of patients stepping up and down reduced from the beginning of the study, although stepping down to step 1 was relatively common in both adults and children. Few patients had a recorded asthma review in the year before reference date (18.8% of children and 14.8% of adults). Although prescribing patterns meant that most patients remained within their treatment step throughout the study, we cannot be sure that this was because their disease was truly stable. The small proportion of patients stepping up/down and the lack of recorded asthma review suggest that patients may not be treated in accordance with BTS/SIGN guidelines.

Incidence of type II diabetes in chronic obstructive pulmonary disease: a nested case-control study.

We investigated the incidence of type II diabetes mellitus (T2DM) among people with COPD and whether exposure to inhaled corticosteroid (ICS) and exacerbation status was associated with T2DM. This descriptive cohort study used primary care data from the Clinical Practice Research Datalink (CPRD). The patient cohort included people with a diagnosis of COPD and previous smoking history registered at a CPRD practice between January 2010 and December 2016. We determined incidence rates by age, gender and deprivation. Using a nested case-control design-where cases and controls are drawn from the cohort population-we matched 1:5 with patients by age, gender and GP practice and estimated odds of T2DM using logistic regression (adjusting for smoking status, deprivation, BMI, hypertension, coronary heart disease and heart failure). We identified 220,971 COPD patients; mean age at COPD diagnosis was 66 years (SD 12) and 54% were male. The incidence rate of T2DM in COPD patients was 1.26 per 100 patient years (95% CI: 1.24-1.28) and was higher among men (1.32 vs 1.18 among women). The adjusted odds ratio for T2DM was 1.47 (95% CI: 1.36-1.60) among frequent exacerbators (≥2 treated exacerbations per year) compared to infrequent exacerbators and the odds ratio for patients receiving high-dose ICS (>800 mcg budesonide equivalent dose) was 1.73 (95% CI 1.65-1.82) compared to patients receiving no ICS therapy. Incidence of T2DM among COPD patients is high and exposure to ICS and frequent exacerbations are associated with a higher risk of T2DM among patients with COPD.

Structural basis for selective inhibition of immunoglobulin E-receptor interactions by an anti-IgE antibody.

Immunoglobulin E (IgE) antibodies play a central role in the allergic response: interaction with FcεRI on mast cells and basophils leads to immediate hypersensitivity reactions upon allergen challenge, while interaction with CD23/FcεRII, expressed on a variety of cells, regulates IgE synthesis among other activities. The receptor-binding IgE-Fc region has recently been found to display remarkable flexibility, from acutely bent to extended conformations, with allosteric communication between the distant FcεRI and CD23 binding sites. We report the structure of an anti-IgE antibody Fab (8D6) bound to IgE-Fc through a mixed protein-carbohydrate epitope, revealing further flexibility and a novel extended conformation with potential relevance to that of membrane-bound IgE in the B cell receptor for antigen. Unlike the earlier, clinically approved anti-IgE antibody omalizumab, 8D6 inhibits binding to FcεRI but not CD23; the structure reveals how this discrimination is achieved through both orthosteric and allosteric mechanisms, supporting therapeutic strategies that retain the benefits of CD23 binding.

Allosteric mechanism of action of the therapeutic anti-IgE antibody omalizumab.

Immunoglobulin E and its interactions with receptors FcϵRI and CD23 play a central role in allergic disease. Omalizumab, a clinically approved therapeutic antibody, inhibits the interaction between IgE and FcϵRI, preventing mast cell and basophil activation, and blocks IgE binding to CD23 on B cells and antigen-presenting cells. We solved the crystal structure of the complex between an omalizumab-derived Fab and IgE-Fc, with one Fab bound to each Cϵ3 domain. Free IgE-Fc adopts an acutely bent structure, but in the complex it is only partially bent, with large-scale conformational changes in the Cϵ3 domains that inhibit the interaction with FcϵRI. CD23 binding is inhibited sterically due to overlapping binding sites on each Cϵ3 domain. Studies of omalizumab Fab binding in solution demonstrate the allosteric basis for FcϵRI inhibition and, together with the structure, reveal how omalizumab may accelerate dissociation of receptor-bound IgE from FcϵRI, exploiting the intrinsic flexibility and allosteric potential of IgE.

IgE binds asymmetrically to its B cell receptor CD23.

The antibody IgE plays a central role in allergic disease mechanisms. Its effector functions are controlled through interactions between the Fc region and two principal cell surface receptors FcεRI and CD23. The interaction with FcεRI is primarily responsible for allergic sensitization and the inflammatory response, while IgE binding to CD23 is involved in the regulation of IgE synthesis and allergen transcytosis. Here we present the crystal structure of a CD23/IgE-Fc complex and conduct isothermal titration calorimetric binding studies. Two lectin-like "head" domains of CD23 bind to IgE-Fc with affinities that differ by more than an order of magnitude, but the crystal structure reveals only one head bound to one of the two identical heavy-chains in the asymmetrically bent IgE-Fc. These results highlight the subtle interplay between receptor binding sites in IgE-Fc and their affinities, the understanding of which may be exploited for therapeutic intervention in allergic disease.

A tool kit for rapid cloning and expression of recombinant antibodies.

Over the last four decades, molecular cloning has evolved tremendously. Efficient products allowing assembly of multiple DNA fragments have become available. However, cost-effective tools for engineering antibodies of different specificities, isotypes and species are still needed for many research and clinical applications in academia. Here, we report a method for one-step assembly of antibody heavy- and light-chain DNAs into a single mammalian expression vector, starting from DNAs encoding the desired variable and constant regions, which allows antibodies of different isotypes and specificity to be rapidly generated. As a proof of principle we have cloned, expressed and characterized functional recombinant tumor-associated antigen-specific chimeric IgE/κ and IgG1/κ, as well as recombinant grass pollen allergen Phl p 7 specific fully human IgE/λ and IgG4/λ antibodies. This method utilizing the antibody expression vectors, available at Addgene, has many applications, including the potential to support simultaneous processing of antibody panels, to facilitate mechanistic studies of antigen-antibody interactions and to conduct early evaluations of antibody functions.

A range of Cℇ3-Cℇ4 interdomain angles in IgE Fc accommodate binding to its receptor CD23.

The antibody IgE plays a central role in allergic disease, functioning principally through two cell-surface receptors: FcℇRI and CD23. FcℇRI on mast cells and basophils mediates the immediate hypersensitivity response, whilst the interaction of IgE with CD23 on B cells regulates IgE production. Crystal structures of the lectin-like `head' domain of CD23 alone and bound to a subfragment of IgE consisting of the dimer of Cℇ3 and Cℇ4 domains (Fcℇ3-4) have recently been determined, revealing flexibility in the IgE-binding site of CD23. Here, a new crystal form of the CD23-Fcℇ3-4 complex with different molecular-packing constraints is reported, which together with the earlier results demonstrates that conformational variability at the interface extends additionally to the IgE Fc and the quaternary structure of its domains.

Conformational plasticity at the IgE-binding site of the B-cell receptor CD23.

IgE antibodies play a central role in allergic disease. They recognize allergens via their Fab regions, whilst their effector functions are controlled through interactions of the Fc region with two principal cell surface receptors, FcɛRI and CD23. Crosslinking of FcɛRI-bound IgE on mast cells and basophils by allergen initiates an immediate inflammatory response, while the interaction of IgE with CD23 on B-cells regulates IgE production. We have determined the structures of the C-type lectin "head" domain of CD23 from seven crystal forms. The thirty-five independent structures reveal extensive conformational plasticity in two loops that are critical for IgE binding.

Mapping of the CD23 binding site on immunoglobulin E (IgE) and allosteric control of the IgE-Fc epsilonRI interaction.

IgE, the antibody that mediates allergic responses, acts as part of a self-regulating protein network. Its unique effector functions are controlled through interactions of its Fc region with two cellular receptors, FcεRI on mast cells and basophils and CD23 on B cells. IgE cross-linked by allergen triggers mast cell activation via FcεRI, whereas IgE-CD23 interactions control IgE expression levels. We have determined the CD23 binding site on IgE, using a combination of NMR chemical shift mapping and site-directed mutagenesis. We show that the CD23 and FcεRI interaction sites are at opposite ends of the Cε3 domain of IgE, but that receptor binding is mutually inhibitory, mediated by an allosteric mechanism. This prevents CD23-mediated cross-linking of IgE bound to FcεRI on mast cells and resulting antigen-independent anaphylaxis. The mutually inhibitory nature of receptor binding provides a degree of autonomy for the individual activities mediated by IgE-FcεRI and IgE-CD23 interactions.

Crystal structure of IgE bound to its B-cell receptor CD23 reveals a mechanism of reciprocal allosteric inhibition with high affinity receptor FcεRI.

The role of IgE in allergic disease mechanisms is performed principally through its interactions with two receptors, FcεRI on mast cells and basophils, and CD23 (FcεRII) on B cells. The former mediates allergic hypersensitivity, the latter regulates IgE levels, and both receptors, also expressed on antigen-presenting cells, contribute to allergen uptake and presentation to the immune system. We have solved the crystal structure of the soluble lectin-like "head" domain of CD23 (derCD23) bound to a subfragment of IgE-Fc consisting of the dimer of Cε3 and Cε4 domains (Fcε3-4). One CD23 head binds to each heavy chain at the interface between the two domains, explaining the known 2:1 stoichiometry and suggesting mechanisms for cross-linking membrane-bound trimeric CD23 by IgE, or membrane IgE by soluble trimeric forms of CD23, both of which may contribute to the regulation of IgE synthesis by B cells. The two symmetrically located binding sites are distant from the single FcεRI binding site, which lies at the opposite ends of the Cε3 domains. Structural comparisons with both free IgE-Fc and its FcεRI complex reveal not only that the conformational changes in IgE-Fc required for CD23 binding are incompatible with FcεRI binding, but also that the converse is true. The two binding sites are allosterically linked. We demonstrate experimentally the reciprocal inhibition of CD23 and FcεRI binding in solution and suggest that the mutual exclusion of receptor binding allows IgE to function independently through its two receptors.