Allergen immunotherapy is effective in patients with allergic rhinitis (AR) and, unlike antiallergic drugs, has been shown to modify the underlying cause of the disease, with proved long-term ...benefits. Subcutaneous immunotherapy (SCIT) has been the gold standard, whereas sublingual immunotherapy (SLIT) has emerged as an effective and safe alternative. Previous Cochrane systematic reviews and meta-analyses have confirmed that both SLIT and SCIT are effective in patients with seasonal AR, whereas evidence for their efficacy in patients with perennial disease has been less convincing. Recent large, adequately powered trials have demonstrated reductions in both symptoms and use of rescue medication in patients with seasonal and those with perennial AR. Here we appraise evidence for SCIT versus SLIT based on indirect evidence from Cochrane reviews and recent well-powered double-blind, randomized controlled trials versus placebo and the limited direct evidence available from randomized blind head-to-head comparisons. At present, based on an overall balance of efficacy and side effects, the patient is in equipoise. Pending definitive comparative trials, choice might be determined largely by the local availability of SCIT and SLIT products of proved value and personal (patient) preference.
Infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is initiated by virus binding to the ACE2 cell-surface receptors
, followed by fusion of the virus and cell membranes to ...release the virus genome into the cell. Both receptor binding and membrane fusion activities are mediated by the virus spike glycoprotein
. As with other class-I membrane-fusion proteins, the spike protein is post-translationally cleaved, in this case by furin, into the S1 and S2 components that remain associated after cleavage
. Fusion activation after receptor binding is proposed to involve the exposure of a second proteolytic site (S2'), cleavage of which is required for the release of the fusion peptide
. Here we analyse the binding of ACE2 to the furin-cleaved form of the SARS-CoV-2 spike protein using cryo-electron microscopy. We classify ten different molecular species, including the unbound, closed spike trimer, the fully open ACE2-bound trimer and dissociated monomeric S1 bound to ACE2. The ten structures describe ACE2-binding events that destabilize the spike trimer, progressively opening up, and out, the individual S1 components. The opening process reduces S1 contacts and unshields the trimeric S2 core, priming the protein for fusion activation and dissociation of ACE2-bound S1 monomers. The structures also reveal refolding of an S1 subdomain after ACE2 binding that disrupts interactions with S2, which involves Asp614
and leads to the destabilization of the structure of S2 proximal to the secondary (S2') cleavage site.
SARS-CoV-2 is thought to have emerged from bats, possibly via a secondary host. Here, we investigate the relationship of spike (S) glycoprotein from SARS-CoV-2 with the S protein of a closely related ...bat virus, RaTG13. We determined cryo-EM structures for RaTG13 S and for both furin-cleaved and uncleaved SARS-CoV-2 S; we compared these with recently reported structures for uncleaved SARS-CoV-2 S. We also biochemically characterized their relative stabilities and affinities for the SARS-CoV-2 receptor ACE2. Although the overall structures of human and bat virus S proteins are similar, there are key differences in their properties, including a more stable precleavage form of human S and about 1,000-fold tighter binding of SARS-CoV-2 to human receptor. These observations suggest that cleavage at the furin-cleavage site decreases the overall stability of SARS-CoV-2 S and facilitates the adoption of the open conformation that is required for S to bind to the ACE2 receptor.
As organisms age, cells accumulate genetic and epigenetic errors that eventually lead to impaired organ function or catastrophic transformation such as cancer. Because aging reflects a stochastic ...process of increasing disorder, cells in an organ will be individually affected in different ways, thus rendering bulk analyses of postmitotic adult cells difficult to interpret. Here, we directly measure the effects of aging in human tissue by performing single-cell transcriptome analysis of 2,544 human pancreas cells from eight donors spanning six decades of life. We find that islet endocrine cells from older donors display increased levels of transcriptional noise and potential fate drift. By determining the mutational history of individual cells, we uncover a novel mutational signature in healthy aging endocrine cells. Our results demonstrate the feasibility of using single-cell RNA sequencing (RNA-seq) data from primary cells to derive insights into genetic and transcriptional processes that operate on aging human tissue.
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•RNA-seq of single cells from donors allows detection of stochastic age-related errors•Cells from older donors have increased transcriptional noise and signs of fate drift•Endocrine pancreas cells display an oxidative stress-related mutational signature•Cellular stress and metabolic genes are high in cells with accumulation of errors
Aging is associated with increased transcriptional dysregulation and loss of identity at the single-cell level
Influenza virus remains a threat because of its ability to evade vaccine-induced immune responses due to antigenic drift. Here, we describe the isolation, evolution, and structure of a broad-spectrum ...human monoclonal antibody (mAb), MEDI8852, effectively reacting with all influenza A hemagglutinin (HA) subtypes. MEDI8852 uses the heavy-chain VH6-1 gene and has higher potency and breadth when compared to other anti-stem antibodies. MEDI8852 is effective in mice and ferrets with a therapeutic window superior to that of oseltamivir. Crystallographic analysis of Fab alone or in complex with H5 or H7 HA proteins reveals that MEDI8852 binds through a coordinated movement of CDRs to a highly conserved epitope encompassing a hydrophobic groove in the fusion domain and a large portion of the fusion peptide, distinguishing it from other structurally characterized cross-reactive antibodies. The unprecedented breadth and potency of neutralization by MEDI8852 support its development as immunotherapy for influenza virus-infected humans.
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•Binding to all influenza A subtypes neutralizing seasonal and pandemic strains•Utilizes a rare VH (VH6-1) and carries a low level of somatic mutations•Highly conserved epitope encompassing fusion peptide and hydrophobic groove•Superior therapeutic window compared to oseltamivir in animals
Identification of a human monoclonal antibody that reacts effectively with all influenza A hemagglutinin subtypes paves the way for developing immunotherapy for people infected with the flu virus.
Allergen immunotherapy is effective for the treatment of allergic rhinitis, allergic asthma, and Hymenoptera venom allergy. In view of potential side effects, cost, and the necessary patient ...commitment, an important question is whether allergen immunotherapy provides persistent clinical benefits after treatment discontinuation. Here, we appraise the existing evidence for long-term effects of both subcutaneous and sublingual immunotherapy in terms of clinical efficacy, immune mechanisms, prevention of asthma development, and prevention of new allergen sensitizations. Evidence from large, randomized, double-blind, placebo-controlled clinical trials that include a follow-up phase after treatment cessation demonstrate long-term efficacy. The data strongly support recommendations in international guidelines that both sublingual and subcutaneous immunotherapy should be continued for a minimum of 3 years to achieve disease modification and long-term tolerance. Grass pollen immunotherapy for seasonal rhinitis may inhibit the onset of asthma symptoms and requirements for asthma medication. Whether early intervention in infancy with mite sublingual immunotherapy may prevent asthma remains to be tested.
Polycomb repressive complex 2 (PRC2) silences gene expression through trimethylation of K27 of histone H3 (H3K27me3) via its catalytic SET domain. A missense mutation in the substrate of PRC2, ...histone H3K27M, is associated with certain pediatric brain cancers and is linked to a global decrease of H3K27me3 in the affected cells thought to be mediated by inhibition of PRC2 activity. We present here the crystal structure of human PRC2 in complex with the inhibitory H3K27M peptide bound to the active site of the SET domain, with the methionine residue located in the pocket that normally accommodates the target lysine residue. The structure and binding studies suggest a mechanism for the oncogenic inhibition of H3K27M. The structure also reveals how binding of repressive marks, like H3K27me3, to the EED subunit of the complex leads to enhancement of the catalytic efficiency of the SET domain and thus the propagation of this repressive histone modification.
AMP-activated protein kinase (AMPK) plays a major role in regulating metabolism and has attracted significant attention as a therapeutic target for treating metabolic disorders. AMPK activity is ...stimulated more than 100-fold by phosphorylation of threonine 172 (Thr
). Binding of AMP to the γ subunit allosterically activates the kinase. Additionally, many small molecules, e.g. 991, have been identified that bind between the kinase domain and the carbohydrate-binding module of the β subunit, stabilising their interaction and leading to activation. It was reported recently that non-phosphorylated Thr
AMPK is activated by AMP and A769662. We present here the crystal structure of non-phosphorylated Thr
AMPK in complex with AMP and 991. This structure reveals that the activation loop, as well as the complex overall, is similar to the Thr
phosphorylated complex. We find that in the presence of AMP and 991 non-phosphorylated Thr
, AMPK is much less active than the Thr
phosphorylated enzyme. In human cells, the basal level of Thr
phosphorylation is very low (∼1%), but is increased 10-fold by treatment with 2-deoxyglucose. In cells lacking the major Thr
kinases, LKB1 and CaMKKβ, Thr
phosphorylation is almost completely abolished, and AMPK activity is virtually undetectable. Our data show that AMP and 991 binding to non-phosphorylated Thr
AMPK can induce an ordered, active-like, conformation of the activation loop explaining how AMPK activity can be measured
without Thr
phosphorylation. However, in a cellular context, phosphorylation of Thr
is critical for significant activation of AMPK.
The Transiting Exoplanet Survey Satellite (TESS) will be conducting a nearly all-sky photometric survey over two years, with a core mission goal to discover small transiting exoplanets orbiting ...nearby bright stars. It will obtain 30 minute cadence observations of all objects in the TESS fields of view, along with two-minute cadence observations of 200,000-400,000 selected stars. The choice of which stars to observe at the two-minute cadence is driven by the need to detect small transiting planets, which leads to the selection of primarily bright, cool dwarfs. We describe the catalogs assembled and the algorithms used to populate the TESS Input Catalog (TIC), including plans to update the TIC with the incorporation of the Gaia second data release in the near future. We also describe a ranking system for prioritizing stars according to the smallest transiting planet detectable, and assemble a Candidate Target List (CTL) using that ranking. We discuss additional factors that affect the ability to photometrically detect and dynamically confirm small planets, and we note additional stellar populations of interest that may be added to the final target list. The TIC is available on the STScI MAST server, and an enhanced CTL is available through the Filtergraph data visualization portal system at the URL http://filtergraph.com/tess_ctl.
Significance The brain comprises an immense number of cells and cellular connections. We describe the first, to our knowledge, single cell whole transcriptome analysis of human adult cortical ...samples. We have established an experimental and analytical framework with which the complexity of the human brain can be dissected on the single cell level. Using this approach, we were able to identify all major cell types of the brain and characterize subtypes of neuronal cells. We observed changes in neurons from early developmental to late differentiated stages in the adult. We found a subset of adult neurons which express major histocompatibility complex class I genes and thus are not immune privileged.
The human brain is a tissue of vast complexity in terms of the cell types it comprises. Conventional approaches to classifying cell types in the human brain at single cell resolution have been limited to exploring relatively few markers and therefore have provided a limited molecular characterization of any given cell type. We used single cell RNA sequencing on 466 cells to capture the cellular complexity of the adult and fetal human brain at a whole transcriptome level. Healthy adult temporal lobe tissue was obtained during surgical procedures where otherwise normal tissue was removed to gain access to deeper hippocampal pathology in patients with medical refractory seizures. We were able to classify individual cells into all of the major neuronal, glial, and vascular cell types in the brain. We were able to divide neurons into individual communities and show that these communities preserve the categorization of interneuron subtypes that is typically observed with the use of classic interneuron markers. We then used single cell RNA sequencing on fetal human cortical neurons to identify genes that are differentially expressed between fetal and adult neurons and those genes that display an expression gradient that reflects the transition between replicating and quiescent fetal neuronal populations. Finally, we observed the expression of major histocompatibility complex type I genes in a subset of adult neurons, but not fetal neurons. The work presented here demonstrates the applicability of single cell RNA sequencing on the study of the adult human brain and constitutes a first step toward a comprehensive cellular atlas of the human brain.
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