Exposure to microplastics and human reproductive outcomes: A systematic review.

BACKGROUND: Microplastics, produced through degradation of environmental plastic pollution, have been detected in human tissues including placenta and fetal meconium. Cell culture and animal studies have demonstrated potential reproductive toxicity of these particles; however, their association with adverse fertility or pregnancy outcomes in humans is not known. OBJECTIVES: To synthesise evidence for the presence of microplastics in human reproductive tissue and their associations with environmental exposures and reproductive outcomes. SEARCH STRATEGY: MEDLINE, Embase, Emcare, CINAHL, ClinicalTrials.gov and ICTRP were searched from inception to 03/02/2023. SELECTION CRITERIA: Studies of human participants, assessing presence of microplastics in reproductive tissues, environmental exposures to microplastics, and fertility- or pregnancy-related outcomes. DATA COLLECTION AND ANALYSIS: Two independent reviewers selected studies and extracted data on study characteristics, microplastics detected, environmental exposures and reproductive outcomes. Narrative synthesis was performed due to methodological heterogeneity. MAIN RESULTS: Of 1094 citations, seven studies were included, covering 96 participants. Microplastics composed of 16 different polymer types were detected in both placental and meconium samples. Two studies reported associations between lifestyle factors (daily water intake, use of scrub cleanser or toothpaste, bottled water and takeaway food) and placental microplastics. One study reported associations between meconium microplastics and reduced microbiota diversity. One reported placental microplastic levels correlated with reduced birthweights and 1-minute Apgar scores. CONCLUSIONS: There is a need for high-quality observational studies to assess the effects of microplastics on human reproductive health.

Equity of travel to access surgery and radiation therapy for lung cancer in New Zealand.

PURPOSE: Centralisation of lung cancer treatment can improve outcomes, but may result in differential access to care for those who do not reside within treatment centres. METHODS: We used national-level cancer registration and health care access data and used Geographic Information Systems (GIS) methods to determine the distance and time to access first relevant surgery and first radiation therapy among all New Zealanders diagnosed with lung cancer (2007-2019; N = 27,869), and compared these outcomes between ethnic groups. We also explored the likelihood of being treated at a high-, medium-, or low-volume hospital. Analysis involved both descriptive and adjusted logistic regression modelling. RESULTS: We found that Maori tend to need to travel further (with longer travel times) to access both surgery (median travel distance: Maori 57 km, European 34 km) and radiation therapy (Maori 75 km, European 35 km) than Europeans. Maori have greater odds of living more than 200 km away from both surgery (adjusted odds ratio [aOR] 1.83, 95% CI 1.49-2.25) and radiation therapy (aOR 1.41, 95% CI 1.25-1.60). CONCLUSIONS: Centralisation of care may often improve treatment outcomes, but it also makes accessing treatment even more difficult for populations who are more likely to live rurally and in deprivation, such as Maori.

Cross Sectional Survey of Antenatal Educators' Views About Current Antenatal Education Provision.

OBJECTIVES: Antenatal education (ANE) is part of National Health Service (NHS) care and is recommended by The National Institute for Health and Care Excellence (NICE) to increase birth preparedness and help pregnant women/birthing people develop coping strategies for labour and birth. We aimed to understand antenatal educator views about how current ANE supports preparedness for childbirth, including coping strategy development with the aim of identifying targets for improvement. METHODS: A United Kingdom wide, cross-sectional online survey was conducted between October 2019 and May 2020. Antenatal educators including NHS midwives and private providers were purposively sampled. Counts and percentages were calculated for closed responses and thematic analysis used for open text responses. RESULTS: Ninety-nine participants responded, 62% of these did not believe that ANE prepared women for labour and birth. They identified practical barriers to accessing ANE, particularly for marginalised groups, including financial and language barriers. Educators believe class content is medically focused, and teaching is of variable quality with some midwives being ill-prepared to deliver antenatal education. 55% of antenatal educators believe the opportunity to develop coping strategies varies between location and educators and only those women who can pay for non-NHS classes are able to access all the coping strategies that can support them with labour and birth. CONCLUSIONS FOR PRACTICE: Antenatal educators believe current NHS ANE does not adequately prepare women for labour and birth, leading to disparities in birth preparedness for those who cannot access non-NHS classes. To reduce this healthcare inequality, NHS classes need to be standardised, with training for midwives in delivering ANE enhanced.

Interventions, outcomes and outcome measurement instruments in stillbirth care research: A systematic review to inform the development of a core outcome set.

BACKGROUND: A core outcome set could address inconsistent outcome reporting and improve evidence for stillbirth care research, which have been identified as an important research priority. OBJECTIVES: To identify outcomes and outcome measurement instruments reported by studies evaluating interventions after the diagnosis of a stillbirth. SEARCH STRATEGY: Amed, BNI, CINAHL, ClinicalTrials.gov, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, Embase, MEDLINE, PsycINFO, and WHO ICTRP from 1998 to August 2021. SELECTION CRITERIA: Randomised and non-randomised comparative or non-comparative studies reporting a stillbirth care intervention. DATA COLLECTION AND ANALYSIS: Interventions, outcomes reported, definitions and outcome measurement tools were extracted. MAIN RESULTS: Forty randomised and 200 non-randomised studies were included. Fifty-eight different interventions were reported, labour and birth care (52 studies), hospital bereavement care (28 studies), clinical investigations (116 studies), care in a multiple pregnancy (2 studies), psychosocial support (28 studies) and care in a subsequent pregnancy (14 studies). A total of 391 unique outcomes were reported and organised into 14 outcome domains: labour and birth; postpartum; delivery of care; investigations; multiple pregnancy; mental health; emotional functioning; grief and bereavement; social functioning; relationship; whole person; subsequent pregnancy; subsequent children and siblings and economic. A total of 242 outcome measurement instruments were used, with 0-22 tools per outcome. CONCLUSIONS: Heterogeneity in outcome reporting, outcome definition and measurement tools in care after stillbirth exists. Considerable research gaps on specific intervention types in stillbirth care were identified. A core outcome set is needed to standardise outcome collection and reporting for stillbirth care research.

Interventions to enhance medication adherence in pregnancy- a systematic review.

BACKGROUND: Sub-optimal medication adherence in pregnant women with chronic disease and pregnancy-related indications has the potential to adversely affect maternal and perinatal outcomes. Adherence to appropriate medications is advocated during and when planning pregnancy to reduce risk of adverse perinatal outcomes relating to chronic disease and pregnancy-related indications. We aimed to systematically identify effective interventions to promote medication adherence in women who are pregnant or planning to conceive and impact on perinatal, maternal disease-related and adherence outcomes. METHODS: Six bibliographic databases and two trial registries were searched from inception to 28th April 2022. We included quantitative studies evaluating medication adherence interventions in pregnant women and women planning pregnancy. Two reviewers selected studies and extracted data on study characteristics, outcomes, effectiveness, intervention description (TIDieR) and risk of bias (EPOC). Narrative synthesis was performed due to study population, intervention and outcome heterogeneity. RESULTS: Of 5614 citations, 13 were included. Five were RCTs, and eight non-randomised comparative studies. Participants had asthma (n = 2), HIV (n = 6), inflammatory bowel disease (IBD; n = 2), diabetes (n = 2) and risk of pre-eclampsia (n = 1). Interventions included education +/- counselling, financial incentives, text messaging, action plans, structured discussion and psychosocial support. One RCT found an effect  of the tested intervention on self-reported antiretroviral adherence but not objective adherence. Clinical outcomes were not evaluated. Seven non-randomised comparative studies found an association between the tested intervention and at least one outcome of interest: four found an association between receiving the intervention and both improved clinical or perinatal outcomes and adherence in women with IBD, gestational diabetes mellitus (GDM), and asthma. One study in women with IBD reported an association between receiving the intervention and maternal outcomes but not for self-reported adherence. Two studies measured only adherence outcomes and reported an association between receiving the intervention and self-reported and/or objective adherence in women with HIV and risk of pre-eclampsia. All studies had high or unclear risk of bias. Intervention reporting was adequate for replication in two studies according to the TIDieR checklist. CONCLUSIONS: There is a need for high-quality RCTs reporting replicable interventions to evaluate medication adherence interventions in pregnant women and those planning pregnancy. These should assess both clinical and adherence outcomes.

Disaggregating proportional multistate lifetables by population heterogeneity to estimate intervention impacts on inequalities.

BACKGROUND: Simulation models can be used to quantify the projected health impact of interventions. Quantifying heterogeneity in these impacts, for example by socioeconomic status, is important to understand impacts on health inequalities. We aim to disaggregate one type of Markov macro-simulation model, the proportional multistate lifetable, ensuring that under business-as-usual (BAU) the sum of deaths across disaggregated strata in each time step returns the same as the initial non-disaggregated model. We then demonstrate the application by deprivation quintiles for New Zealand (NZ), for: hypothetical interventions (50% lower all-cause mortality, 50% lower coronary heart disease mortality) and a dietary intervention to substitute 59% of sodium with potassium chloride in the food supply. METHODS: We developed a disaggregation algorithm that iteratively rescales mortality, incidence and case-fatality rates by time-step of the model to ensure correct total population counts were retained at each step. To demonstrate the algorithm on deprivation quintiles in NZ, we used the following inputs: overall (non-disaggregated) all-cause mortality & morbidity rates, coronary heart disease incidence & case fatality rates; stroke incidence & case fatality rates. We also obtained rate ratios by deprivation for these same measures. Given all-cause and cause-specific mortality rates by deprivation quintile, we derived values for the incidence, case fatality and mortality rates for each quintile, ensuring rate ratios across quintiles and the total population mortality and morbidity rates were returned when averaged across groups. The three interventions were then run on top of these scaled BAU scenarios. RESULTS: The algorithm exactly disaggregated populations by strata in BAU. The intervention scenario life years and health adjusted life years (HALYs) gained differed slightly when summed over the deprivation quintile compared to the aggregated model, due to the stratified model (appropriately) allowing for differential background mortality rates by strata. Modest differences in health gains (HALYs) resulted from rescaling of sub-population mortality and incidence rates to ensure consistency with the aggregate population. CONCLUSION: Policy makers ideally need to know the effect of population interventions estimated both overall, and by socioeconomic and other strata. We demonstrate a method and provide code to do this routinely within proportional multistate lifetable simulation models and similar Markov models.

A rapidly expanding cutaneous tumour in the context of a Janus kinase inhibitor agent following allogeneic stem cell transplant.

Ruxolitinib is a selective, Janus kinase (JAK)1 and JAK2 inhibitor, which is effective in management of chronic graft-versus-host disease (cGvHD). However, the ensuing immunosuppressive effects can give rise to aggressive cutaneous tumours, including Merkel cell carcinoma. We present this case to highlight the development of cutaneous tumours with ruxolitinib, an increasingly used therapy, and the challenge of managing such tumours in the context of refractory cGvHD. Click here for the corresponding questions to this CME article.

Generation and Characterization of Native and Sialic Acid-Deficient IgE.

Efficient characterization of IgE antibodies and their glycan structures is required for understanding their function in allergy and in the emerging AllergoOncology field for antibody immunotherapy. We report the generation, glyco-profiling and functional analysis of native and sialic acid-deficient glyco-engineered human IgE. The antibodies produced from human embryonic kidney cells were purified via a human IgE class-specific affinity matrix and structural integrity was confirmed by SDS-PAGE and size-exclusion chromatography (SEC). Purified IgEs specific for the tumor-associated antigens Chondroitin Sulfate Proteoglycan 4 (CSPG4-IgE) and Human Epidermal Growth Factor Receptor 2 (HER2-IgE) were devoid of by-products such as free light chains. Using neuraminidase-A, we generated sialic acid-deficient CSPG4-IgE as example glyco-engineered antibody. Comparative glycan analyses of native and glyco-engineered IgEs by Hydrophilic interaction liquid chromatography (HILIC)-high performance liquid chromatography (HPLC) indicated loss of sialic acid terminal residues and differential glycan profiles. Native and glyco-engineered CSPG4-IgEs recognized Fc receptors on the surface of human FcεRI-expressing rat basophilic leukemia RBL-SX38 cells, and of CD23/FcεRII-expressing human RPMI-8866 B-lymphocytes and bound to CSPG4-expressing A2058 human melanoma cells, confirming Fab-mediated recognition. When cross-linked on the cell surface, both IgEs triggered RBL-SX38 degranulation. We demonstrate efficient generation and functional competence of recombinant native and sialic acid-deficient IgEs.

Creating careful circularities: Community composting in New York City.

While matters of food waste and soil have become vital research arenas, compost remains the Cinderella of human geographical enquiry. In response, this paper brings compost to the centre of debates at the intersection of diverse economies and circular economy. In particular, the concept of community composting and the care involved in such practices is used to offset and problematise the technoscientific bias in circular economy discourses. Extending feminist perspectives on care in soil studies, this paper focuses on the careful circularities that are realised through community composting in New York City. This case study provides not only a material space for examining community composting but also a unique opportunity to consider the colliding worlds of worth that operate in and around urban sustainability transitions to zero waste. Drawing empirical insights from interviews, participant observation, and document analysis, this paper argues for a sensitisation of circular economy policy and research to matters of care and diverse economies as a means to better understand motivations, justifications, and outcomes of efforts to reorient food systems onto more sustainable pathways. We argue that privileging care in this way helps to shift focus away from dominant narratives of "scaling-up" towards sustainability to a more relational perspective that sees transformation in connecting, deepening, and even scaling-down. This means attending to the micro as well as macro transformations needed to enact the required sustainability transitions.

Pregnant women's experiences of social distancing behavioural guidelines during the Covid-19 pandemic 'lockdown' in the UK, a qualitative interview study.

BACKGROUND: Covid-19 triggered the rapid roll-out of mass social distancing behavioural measures for infection control. Pregnant women were categorised as 'at risk' requiring extra vigilance with behavioural guidelines. Their understanding and ability to adhere to recommendations was unknown. OBJECTIVES: To complete a behavioural analysis of the determinants of recommended social distancing behaviour in pregnant women, according to the 'capability, opportunity, motivation and behaviour' ('COM-B') model to inform the development of recommendations/materials to support pregnant women in understanding and adhering to behavioural guidelines. DESIGN: Qualitative interview study with pregnant women in the Bristol area (UK). METHODS: Semi-structured telephone/videoconference interviews were conducted following a topic guide informed by the COM-B model, transcribed verbatim and subjected to framework analysis. Infographic materials were iteratively produced with stakeholder consultation, to support pregnant women. RESULTS: Thirty-one women participated (selected for demographic range). Women reported adhering to social distancing recommendations and intended to continue. COM-B analysis identified gaps in understanding around risk, vulnerability, and the extent of required social distancing, as well as facilitators of social distancing behaviour (e.g. social support, motivation to stay safe, home environment/resources). Additional themes around detrimental mental health effects and changes to maternity healthcare from the social distancing measures were identified. Infographic resources (plus midwife report) addressing women's key concerns were produced and disseminated. CONCLUSIONS: The COM-B model provided useful details of determinants of pregnant women's adherence to social distancing behaviours. The confusion of what being 'at risk' meant and varying interpretation of what was expected indicates a need for greater clarity around categories and guidance. The loss of maternity care and negative mental health effects of social distancing suggest a growing area of unmet health needs to be addressed in future.

Structure of a patient-derived antibody in complex with allergen reveals simultaneous conventional and superantigen-like recognition.

Antibodies classically bind antigens via their complementarity-determining regions, but an alternative mode of interaction involving V-domain framework regions has been observed for some B cell "superantigens." We report the crystal structure of an antibody employing both modes of interaction simultaneously and binding two antigen molecules. This human antibody from an allergic individual binds to the grass pollen allergen Phl p 7. Not only are two allergen molecules bound to each antibody fragment (Fab) but also each allergen molecule is bound by two Fabs: One epitope is recognized classically, the other in a superantigen-like manner. A single allergen molecule thus cross-links two identical Fabs, contrary to the one-antibody-one-epitope dogma, which dictates that a dimeric allergen at least is required for this to occur. Allergens trigger immediate hypersensitivity reactions by cross-linking receptor-bound IgE molecules on effector cells. We found that monomeric Phl p 7 induced degranulation of basophils sensitized solely with this monoclonal antibody expressed as an IgE, demonstrating that the dual specificity has functional consequences. The monomeric state of Phl p 7 and two structurally related allergens was confirmed by size-exclusion chromatography and multiangle laser light scattering, and the results were supported by degranulation studies with the related allergens, a second patient-derived allergen-specific antibody lacking the nonclassical binding site, and mutagenesis of the nonclassically recognized allergen epitope. The antibody dual reactivity and cross-linking mechanism not only have implications for understanding allergenicity and allergen potency but, importantly, also have broader relevance to antigen recognition by membrane Ig and cross-linking of the B cell receptor.

Implementation of photographic triage in a paediatric dental, orthodontic, and maxillofacial department during COVID-19.

BACKGROUND: During the COVID-19 pandemic, limitations were placed on face-to-face encounters in dentistry and oral and maxillofacial surgery (OMFS) in order to promote physical distancing and reduce viral propagation. To facilitate continued assessment of dental, orthodontic, and maxillofacial emergencies, a photographic triage system was initiated at Alder Hey Children's Hospital (AHCH). We will discuss the benefits this system offers at a patient, clinician, departmental, and NHS service level. AIM: To share our experience of photographic triage during the first 3 months of COVID-19 lockdown, lessons learned, and recommendations. DESIGN: Prospective data collection over 3 months. RESULTS: 220 photographic referrals were received, and swelling (30%) and dental trauma (27%) were the most common presenting complaints. 57% of referrals were not seen, 23% were seen semi-urgently, and 20% booked for outpatient review. Of those seen, 7 children were seen elsewhere and 44 were seen face-to-face at AHCH, with 8 being admitted. CONCLUSION: Photographic triage reduced physical encounters and proved useful in training junior staff, assessment of new patient referrals, and first on-call from home. Implementation should be considered throughout dental, orthodontic, and OMFS departments nationwide. In the event of a COVID-19 resurgence or emergence of a new pandemic, photographic triage could facilitate physical distancing and service provision.

Can cost-effectiveness results be combined into a coherent league table? Case study from one high-income country.

BACKGROUND: Doubts exist around the value of compiling league tables for cost-effectiveness results for health interventions, primarily due to methods differences. We aimed to determine if a reasonably coherent league table could be compiled using published studies for one high-income country: New Zealand (NZ). METHODS: Literature searches were conducted to identify NZ-relevant studies published in the peer-reviewed journal literature between 1 January 2010 and 8 October 2017. Only studies with the following metrics were included: cost per quality-adjusted life-year or disability-adjusted life-year or life-year (QALY/DALY/LY). Key study features were abstracted and a summary league table produced which classified the studies in terms of cost-effectiveness. RESULTS: A total of 21 cost-effectiveness studies which met the inclusion criteria were identified. There were some large methodological differences between the studies, particularly in the time horizon (1 year to lifetime) but also discount rates (range 0 to 10%). Nevertheless, we were able to group the incremental cost-effectiveness ratios (ICERs) into general categories of being reported as cost-saving (19%), cost-effective (71%), and not cost-effective (10%). The median ICER (adjusted to 2017 NZ$) was ~ $5000 per QALY/DALY/LY (~US$3500). However, for some interventions, there is high uncertainty around the intervention effectiveness and declining adherence over time. CONCLUSIONS: It seemed possible to produce a reasonably coherent league table for the ICER values from different studies (within broad groupings) in this high-income country. Most interventions were cost-effective and a fifth were cost-saving. Nevertheless, study methodologies did vary widely and researchers need to pay more attention to using standardised methods that allow their results to be included in future league tables.

SHARE IT: Co-designing a sustainability impact assessment framework for urban food sharing initiatives.

Urban food systems must undergo a significant transformation if they are to avoid impeding the achievement of UN Sustainable Development Goals. One reconfiguration with claimed sustainability benefits is ICT-mediated food sharing - an umbrella term used to refer to technologically-augmented collective or collaborative practices around growing, cooking, eating and redistributing food - which some argue improves environmental efficiencies by reducing waste, providing opportunities to make or save money, building social networks and generally enhancing well-being. However, most sustainability claims for food sharing have not been evidenced by systematically collected and presented data. In this paper we document our response to this mismatch between claims and evidence through the development of the SHARECITY sustainability Impact assessment Toolkit (SHARE IT); a novel Sustainability Impact Assessment (SIA) framework which has been co-designed with food sharing initiatives to better indicate the impact of food-sharing initiatives in urban food systems. We demonstrate that while several SIA frameworks have been developed to evaluate food systems at the urban scale, they contain few measures that specifically account for impacts of the sharing that initiatives undertake. The main body of the paper focuses on the co-design process undertaken with food sharing initiatives based in Dublin and London. Attention is paid to how two core goals were achieved: 1) the identification of a coherent SIA framework containing appropriate indicators for the activities of food sharing initiatives; and 2) the development of an open access online toolkit for in order to make SIA reporting accessible for food sharing initiatives. In conclusion, the co-design process revealed a number of technical and conceptual challenges, but it also stimulated creative responses to these challenges.

Human IgG4: a structural perspective.

IgG4, the least represented human IgG subclass in serum, is an intriguing antibody with unique biological properties, such as the ability to undergo Fab-arm exchange and limit immune complex formation. The lack of effector functions, such as antibody-dependent cell-mediated cytotoxicity and complement-dependent cytotoxicity, is desirable for therapeutic purposes. IgG4 plays a protective role in allergy by acting as a blocking antibody, and inhibiting mast cell degranulation, but a deleterious role in malignant melanoma, by impeding IgG1-mediated anti-tumor immunity. These findings highlight the importance of understanding the interaction between IgG4 and Fcγ receptors. Despite a wealth of structural information for the IgG1 subclass, including complexes with Fcγ receptors, and structures for intact antibodies, high-resolution crystal structures were not reported for IgG4-Fc until recently. Here, we highlight some of the biological properties of human IgG4, and review the recent crystal structures of IgG4-Fc. We discuss the unexpected conformations adopted by functionally important Cγ2 domain loops, and speculate about potential implications for the interaction between IgG4 and FcγRs.

Structure and dynamics of IgE-receptor interactions: FcεRI and CD23/FcεRII.

Immunoglobulin E (IgE) is well known for its role in allergic disease, the manifestations of which are mediated through its two Fc receptors, FcεRI and CD23 (FcεRII). IgE and its interactions with these receptors are therefore potential targets for therapeutic intervention, and exciting progress has been made in this direction. Furthermore, recent structural studies of IgE-Fc, the two receptors, and of their complexes, have revealed a remarkable degree of plasticity at the IgE-CD23 interface and an even more remarkable degree of dynamic flexibility within the IgE molecule. Indeed, there is allosteric communication between the two receptor-binding sites, which we now know are located at some distance from each other in IgE-Fc (at opposite ends of the Cε3 domain). The conformational changes associated with FcεRI and CD23 binding to IgE-Fc ensure that their interactions are mutually incompatible, and it may be that this functional imperative has driven IgE to evolve such a dynamic structure. Appreciation of these new structural data has revised our view of IgE structure, shed light on the co-evolution of antibodies and their receptors, and may open up new therapeutic opportunities.

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.

Public perceptions of bacterial whole-genome sequencing for tuberculosis.

The ability to sequence a bacterial genome in less than 1 day represents a step change for clinical microbiology. Genomic data can be used to investigate suspected outbreaks and rapidly to identify multidrug-resistant organisms. We held an open public debate to explore public understanding and perceptions of bacterial whole-genome sequencing (WGS), which we describe here.

Antibodies and superantibodies in patients with chronic rhinosinusitis with nasal polyps.

BACKGROUND: Chronic rhinosinusitis with nasal polyps is associated with local immunoglobulin hyperproduction and the presence of IgE antibodies against Staphylococcus aureus enterotoxins (SAEs). Aspirin-exacerbated respiratory disease is a severe form of chronic rhinosinusitis with nasal polyps in which nearly all patients express anti-SAEs. OBJECTIVES: We aimed to understand antibodies reactive to SAEs and determine whether they recognize SAEs through their complementarity-determining regions (CDRs) or framework regions. METHODS: Labeled staphylococcal enterotoxin (SE) A, SED, and SEE were used to isolate single SAE-specific B cells from the nasal polyps of 3 patients with aspirin-exacerbated respiratory disease by using fluorescence-activated cell sorting. Recombinant antibodies with "matched" heavy and light chains were cloned as IgG1, and those of high affinity for specific SAEs, assayed by means of ELISA and surface plasmon resonance, were recloned as IgE and antigen-binding fragments. IgE activities were tested in basophil degranulation assays. RESULTS: Thirty-seven SAE-specific, IgG- or IgA-expressing B cells were isolated and yielded 6 anti-SAE clones, 2 each for SEA, SED, and SEE. Competition binding assays revealed that the anti-SEE antibodies recognize nonoverlapping epitopes in SEE. Unexpectedly, each anti-SEE mediated SEE-induced basophil degranulation, and IgG1 or antigen-binding fragments of each anti-SEE enhanced degranulation by the other anti-SEE. CONCLUSIONS: SEEs can activate basophils by simultaneously binding as antigens in the conventional manner to CDRs and as superantigens to framework regions of anti-SEE IgE in anti-SEE IgE-FcεRI complexes. Anti-SEE IgG1s can enhance the activity of anti-SEE IgEs as conventional antibodies through CDRs or simultaneously as conventional antibodies and as "superantibodies" through CDRs and framework regions to SEEs in SEE-anti-SEE IgE-FcεRI complexes.

Thermal sensitivity and flexibility of the Cε3 domains in immunoglobulin E.

Immunoglobulin E (IgE) is the antibody that plays a central role in the mechanisms of allergic diseases such as asthma. Interactions with its receptors, FcεRI on mast cells and CD23 on B cells, are mediated by the Fc region, a dimer of the Cε2, Cε3 and Cε4 domains. A sub-fragment lacking the Cε2 domains, Fcε3-4, also binds to both receptors, although receptor binding almost exclusively involves the Cε3 domains. This domain also contains the N-linked glycosylation site conserved in other isotypes. We report here the crystal structures of IgE-Fc and Fcε3-4 at the highest resolutions yet determined, 1.75Šand 2.0Šrespectively, revealing unprecedented detail regarding the carbohydrate and its interactions with protein domains. Analysis of the crystallographic B-factors of these, together with all earlier IgE-Fc and Fcε3-4 structures, shows that the Cε3 domains exhibit the greatest intrinsic flexibility and quaternary structural variation within IgE-Fc. Intriguingly, both well-ordered carbohydrate and disordered polypeptide can be seen within the same Cε3 domain. A simplified method for comparing the quaternary structures of the Cε3 domains in free and receptor-bound IgE-Fc structures is presented, which clearly delineates the FcεRI and CD23 bound states. Importantly, differential scanning fluorimetric analysis of IgE-Fc and Fcε3-4 identifies Cε3 as the domain most susceptible to thermally-induced unfolding, and responsible for the characteristically low melting temperature of IgE.