Parkinson's disease-associated mutations in α-synuclein alters its lipid-bound state.

Lipid-binding properties of α-synuclein play a central role in protein aggregation and progression of Parkinson's disease (PD). α-Synuclein, an intrinsically disordered protein, binds to lipid membranes through the formation of two amphipathic helices that insert into the lipid bilayer. All disease-associated single point mutations have been identified to be within these helical regions of α-synuclein: V15A, A30P, E46K, H50Q, G51D, A53T, and A53V. However, the effects of these mutations on the bound states of the two α helices of the protein have yet to be fully characterized. In this report, we use a tryptophan fluorescence assay to measure the binding of the α helices of these PD-associated mutants to lipid membranes within the lipid-depletion regime. We characterize the binding behavior of each helix, revealing that, generally, the PD-associated mutants shift the equilibrium bound state away from the N-terminal helix of the protein toward helix 2 at lower lipid concentrations. Altogether, our results indicate that disruption to the equilibrium binding of the two α helices of α-synuclein could play a role in PD progression.

One School of Pharmacy's Experience of Talking With Student Pharmacists About Coping With Patient Death.

OBJECTIVE: End-of-life care is an important aspect of health care profession education; however, little has been published about preparing student pharmacists for the emotional impact of their patient dying. This manuscript describes using a question-and-answer seminar with a mixed faculty and student panel, members of which had been impacted by a patient's death, as a stimulus for student reflection on how they might cope in similar circumstances. METHODS: Students attending the seminar were provided a guiding prompt for reflecting on what would help them respond to a patient's death. The resulting essays were analyzed for 5 themes inspired by the guiding prompt, and categories of responses for each theme were created using an inductive approach. Descriptive statistics were used to analyze the results. RESULTS: A total of 69 student pharmacists submitted essays and 552 statements were identified and coded into 5 themes and 23 categories. The most commonly addressed theme was "personal strategies" for coping with loss, whereas the least addressed was "resources" available to pharmacists. The most commonly mentioned strategies were "acknowledge your emotions" and "talk with others." CONCLUSION: A simple-to-implement seminar was effective at stimulating student reflection on how they would cope with a patient's death. Although some students had already experienced the death of a patient, others stated they had never considered that their patients may die, supporting the importance of the panel discussion.

Delivery of loaded MR1 monomer results in efficient ligand exchange to host MR1 and subsequent MR1T cell activation.

MR1-restricted T cells have been implicated in microbial infections, sterile inflammation, wound healing and cancer. Similar to other antigen presentation molecules, evidence supports multiple, complementary MR1 antigen presentation pathways. To investigate ligand exchange pathways for MR1, we used MR1 monomers and tetramers loaded with 5-(2-oxopropylideneamino)-6-d-ribitylaminouracil (5-OP-RU) to deliver the antigen. Using MR1-deficient cells reconstituted with wild-type MR1 or MR1 molecules that cannot bind 5-OP-RU, we show that presentation of monomer-delivered 5-OP-RU is dependent on cellular MR1 and requires the transfer of ligand from the soluble molecule onto MR1 expressed by the antigen presenting cell. This mode of antigen delivery strengthens the evidence for post-ER ligand exchange pathways for MR1, which could represent an important avenue by which MR1 acquires antigens derived from endocytosed pathogens.

Multiple Isomers of Photolumazine V Bind MR1 and Differentially Activate MAIT Cells.

In response to microbial infection, the nonclassical Ag-presenting molecule MHC class I-related protein 1 (MR1) presents secondary microbial metabolites to mucosal-associated invariant T (MAIT) cells. In this study, we further characterize the repertoire of ligands captured by MR1 produced in Hi5 (Trichoplusia ni) cells from Mycobacterium smegmatis via mass spectrometry. We describe the (to our knowledge) novel MR1 ligand photolumazine (PL)V, a hydroxyindolyl-ribityllumazine with four isomers differing in the positioning of a hydroxyl group. We show that all four isomers are produced by M. smegmatis in culture and that at least three can induce MR1 surface translocation. Furthermore, human MAIT cell clones expressing distinct TCR ß-chains differentially responded to the PLV isomers, demonstrating that the subtle positioning of a single hydroxyl group modulates TCR recognition. This study emphasizes structural microheterogeneity within the MR1 Ag repertoire and the remarkable selectivity of MAIT cell TCRs.

The impact of a pharmacist-led cultural competence training on provider perceived preparedness and clinical care in patients with diabetes of Asian descent.

BACKGROUND: Patients of Asian descent are under-represented in the U.S. health care system and provider cultural competence is inadequate in addressing Asian health disparities. OBJECTIVES: The purpose of this study was to evaluate the impact of the pharmacist-led cultural competence training on provider self-perceived preparedness and diabetes-related health outcomes in patients of Asian descent. METHODS: This study is a cross-sectional followed by a quasi-experimental design conducted in 2 phases in a primary care clinic. Phase one evaluated the association of providers' cross-cultural care survey (CCCS) scores with patients' diabetic health indices: hemoglobin A1c (HbA1C), systolic blood pressure (SBP), diastolic blood pressure, and body mass index. Phase 2 examined the impact of pharmacist-led cultural competence training on providers' cross-cultural competency using survey analysis as well as pre- and post-training diabetic health indices in patients of Asian descent. RESULTS: Phase 1 CCCS results showed baseline cross-cultural competence of the providers is inadequate (N = 9 providers). Furthermore, a significant negative correlation was found between providers' CCCS score and patients' HbA1C (N = 49, P = 0.04). Phase 2 showed that cultural competence training significantly reduced providers' self-perceived "un-preparedness" to care for patients of alternative cultures (N = 30 providers). Average diabetic health indices for all patients (N = 95) before and after the training were not significantly different. In the subset of patients with uncontrolled diabetes (HbA1C ≥ 7), SBP and HbA1C were significantly reduced after the training (P = 0.032 and P = 0.039, respectively). CONCLUSIONS: Pharmacist-led cultural competence training had a positive impact on provider self-assessment and diabetic clinical outcomes in uncontrolled patients.

MFG-E8: a model of multiple binding modes associated with ps-binding proteins.

Membrane-binding proteins often associate with lipid membranes through a singular binding interface which is generally modeled as a two-state system: bound or unbound. However, even a single interface can engage with more than one mode of binding since a variety of interactions can contribute to the binding event. Unfortunately, the ability to clearly delineate the different binding modes of a singular binding interface has been elusive with existing models. Here, we present a study on milk fat globule EGF factor 8 (MFG-E8), which belongs to a class of proteins that identifies and binds phosphatidylserine (PS). These proteins detect membrane dysregulation implicated in exposed PS in apoptosis and malignant cells. In order to elucidate the factors affecting the binding of MFG-E8, we used a model system consisting of a series of lipid vesicles with varying PS mole fraction to identify the sensitivity of MFG-E8's binding affinity to changes in electrostatics using a tryptophan fluorescence spectral shift assay. Using a newly developed model, we experimentally identified three binding modes, each associated with a different number of PS lipids, with its cooperativity for binding being enhanced by the availability of negatively charged lipids. X-ray reflectivity experiments additionally suggest that MFG-E8's binding modes are influenced by membrane packing. The protocols established for elucidating MFG-E8's interaction with lipid membranes under different membrane conditions can be applied to the study of other membrane-binding proteins that target specific membrane attributes, such as fluidity and electrostatics, and help elucidate these membrane targeting mechanisms and their subsequent binding events.

Biochemical and biophysical characterization of natural polyreactivity in antibodies.

To become specialized binders, antibodies undergo a process called affinity maturation to maximize their binding affinity. Despite this process, some antibodies retain low-affinity binding to diverse epitopes in a phenomenon called polyreactivity. Here we seek to understand the molecular basis of this polyreactivity in antibodies. Our results highlight that polyreactive antigen-binding fragments (Fabs) bind their targets with low affinities, comparable to T cell receptor recognition of autologous classical major histocompatibility complex. Extensive mutagenic studies find no singular amino acid residue or biochemical property responsible for polyreactive interaction, suggesting that polyreactive antibodies use multiple strategies for engagement. Finally, our crystal structures and all-atom molecular dynamics simulations of polyreactive Fabs show increased rigidity compared to their monoreactive relatives, forming a neutral and accessible platform for diverse antigens to bind. Together, these data support a cooperative strategy of rigid neutrality in establishing the polyreactive status of an antibody molecule.

Ligand-induced segregation from large cell-surface phosphatases is a critical step in γδ TCR triggering.

Gamma/delta (γδ) T cells are unconventional adaptive lymphocytes that recognize structurally diverse ligands via somatically-recombined antigen receptors (γδ TCRs). The molecular mechanism by which ligand recognition initiates γδ TCR signaling, a process known as TCR triggering, remains elusive. Unlike αß TCRs, γδ TCRs are not mechanosensitive, and do not require coreceptors or typical binding-induced conformational changes for triggering. Here, we show that γδ TCR triggering by nonclassical MHC class Ib antigens, a major class of ligands recognized by γδ T cells, requires steric segregation of the large cell-surface phosphatases CD45 and CD148 from engaged TCRs at synaptic close contact zones. Increasing access of these inhibitory phosphatases to sites of TCR engagement, by elongating MHC class Ib ligands or truncating CD45/148 ectodomains, abrogates TCR triggering and T cell activation. Our results identify a critical step in γδ TCR triggering and provide insight into the core triggering mechanism of endogenous and synthetic tyrosine-phosphorylated immunoreceptors.

CRISPR screens decode cancer cell pathways that trigger γδ T cell detection.

γδ T cells are potent anticancer effectors with the potential to target tumours broadly, independent of patient-specific neoantigens or human leukocyte antigen background1-5. γδ T cells can sense conserved cell stress signals prevalent in transformed cells2,3, although the mechanisms behind the targeting of stressed target cells remain poorly characterized. Vγ9Vδ2 T cells-the most abundant subset of human γδ T cells4-recognize a protein complex containing butyrophilin 2A1 (BTN2A1) and BTN3A1 (refs. 6-8), a widely expressed cell surface protein that is activated by phosphoantigens abundantly produced by tumour cells. Here we combined genome-wide CRISPR screens in target cancer cells to identify pathways that regulate γδ T cell killing and BTN3A cell surface expression. The screens showed previously unappreciated multilayered regulation of BTN3A abundance on the cell surface and triggering of γδ T cells through transcription, post-translational modifications and membrane trafficking. In addition, diverse genetic perturbations and inhibitors disrupting metabolic pathways in the cancer cells, particularly ATP-producing processes, were found to alter BTN3A levels. This induction of both BTN3A and BTN2A1 during metabolic crises is dependent on AMP-activated protein kinase (AMPK). Finally, small-molecule activation of AMPK in a cell line model and in patient-derived tumour organoids led to increased expression of the BTN2A1-BTN3A complex and increased Vγ9Vδ2 T cell receptor-mediated killing. This AMPK-dependent mechanism of metabolic stress-induced ligand upregulation deepens our understanding of γδ T cell stress surveillance and suggests new avenues available to enhance γδ T cell anticancer activity.

Deaza-modification of MR1 ligands modulates recognition by MR1-restricted T cells.

MR1-restricted T (MR1T) cells recognize microbial small molecule metabolites presented on the MHC Class I-like molecule MR1 and have been implicated in early effector responses to microbial infection. As a result, there is considerable interest in identifying chemical properties of metabolite ligands that permit recognition by MR1T cells, for consideration in therapeutic or vaccine applications. Here, we made chemical modifications to known MR1 ligands to evaluate the effect on MR1T cell activation. Specifically, we modified 6,7-dimethyl-8-D-ribityllumazine (DMRL) to generate 6,7-dimethyl-8-D-ribityldeazalumazine (DZ), and then further derivatized DZ to determine the requirements for retaining MR1 surface stabilization and agonistic properties. Interestingly, the IFN-γ response toward DZ varied widely across a panel of T cell receptor (TCR)-diverse MR1T cell clones; while one clone was agnostic toward the modification, most displayed either an enhancement or depletion of IFN-γ production when compared with its response to DMRL. To gain insight into a putative mechanism behind this phenomenon, we used in silico molecular docking techniques for DMRL and its derivatives and performed molecular dynamics simulations of the complexes. In assessing the dynamics of each ligand in the MR1 pocket, we found that DMRL and DZ exhibit differential dynamics of both the ribityl moiety and the aromatic backbone, which may contribute to ligand recognition. Together, our results support an emerging hypothesis for flexibility in MR1:ligand-MR1T TCR interactions and enable further exploration of the relationship between MR1:ligand structures and MR1T cell recognition for downstream applications targeting MR1T cells.

Setmelanotide: A Novel Targeted Treatment for Monogenic Obesity.

Objective: To review clinical data regarding the newly approved drug setmelanotide, an injectable melanocortin 4 receptor (MC4R) agonist, for chronic weight management in adults and children aged 6 years and older with monogenic obesity. Data Sources: A literature review was performed by searching MEDLINE, SCOPUS, and EMBASE for all relevant English-language articles published between January 1, 1996, and November 30, 2021, using search terms obesity, setmelanotide, Imcivree, and MC4R agonist. Study Selection/Data Extraction: This review included two phase 2, two phase 3, and one ongoing clinical trial evaluating the efficacy and/or safety of setmelanotide. Data Synthesis: Setmelanotide demonstrates statistically significant weight loss with at least a 10% decrease in body weight after 1 year and decreased appetite in phase 2 and phase 3 clinical trials. The most common adverse effects included injection site reaction (96%), skin hyperpigmentation (78%), nausea (56%), headache (41%), and diarrhea (37%). Place in Therapy: Setmelanotide is the first and only Food and Drug Administration-approved medication for the treatment of proopiomelanocortin, proprotein convertase subtilisin/kexin type 1, and leptin receptor deficiency in patients with obesity. It may be used in children and adults who have received genetic testing and exhibited extreme obesity before age five. Setmelanotide is a daily subcutaneous injection and may be difficult to afford for patients. Conclusion: Setmelanotide is an effective treatment in patients with obesity and indicated genetic disorders.

An Evaluation of US Medical Schools' Reproductive Health and Family Planning Curricula.

Background and Objectives: Knowledge and competency in the topics of reproductive health and family planning are important for primary care physicians. Given the high rates of unintended pregnancy, increasing rates of infertility and other gynecologic conditions, it is important for medical students, many of whom will become primary care physicians, to receive good foundational knowledge of reproductive health topics. The objective of this research project was to investigate the current curricula at US medical schools to determine the breadth and extent of education that medical students receive in reproductive health. Methods: Medical students and faculty at 20 US medical schools shared all relevant materials from their required reproductive health curriculum used between 2016-2019, including syllabi, PowerPoint lectures, and official class handouts that were available to all students. From these, the number of mentions of 69 reproductive health-related terms were counted, including those related to family planning methods, abortion, ectopic pregnancy, reproductive counseling, and infertility. Results: Of the over 9000 mentions of reproductive health terms, approximately half of mentions were related to family planning, with 10% related to abortion, 10% to infertility, and 6% to reproductive counseling. Family planning strategies emphasized oral contraceptives and long-acting reversible contraceptives with limited mentions of natural or fertility awareness-based methods. Conclusions: This data demonstrates opportunities for broadening reproductive health education in medical school so that future primary care physicians are prepared to discuss the full range of reproductive options for their patients.

Evaluation of Provider Implementation of the 2019 American College of Cardiology and American Heart Association Aspirin for Primary Prevention Guideline Recommendations for Older People.

Design Retrospective chart review study using electronic medical record data from Inova Health System patients. Setting All cardiology, endocrinology, and primary care outpatient clinics operated by Inova Medical Group (IMG) in Northern Virginia. Participants Participants included were 70 years of age or older and taking aspirin 81 mg as of April 1, 2019. They had completed at least one visit with an IMG provider in primary care, cardiology, or endocrinology clinics between April 1, 2019, and February 17, 2020. Main Outcome Measures The primary outcome of this study was percentage of older people seen by a primary care physician, cardiologist, or endocrinologist since guideline publication who were continued on aspirin for primary prevention. Results The percentage of participants continued on aspirin for primary prevention was 92% versus 8.0% who were discontinued (P < 0.0001). Differences in subgroup analyses based on smoking history, diagnosis of diabetes, or history of venous thromboembolism were not statistically significant. Conclusion There was a significantly greater rate of aspirin continuation versus discontinuation among patients 70 years of age and older in the setting of primary cardiovascular prevention. Based on this result, most primary care physicians, endocrinologists, and cardiologists at this institution have chosen to continue aspirin in older people following the 2019 American College of Cardiology/American Heart Association guideline statement publication.

The molecular characterization of antibody binding to a superantigen-like protein from a commensal microbe.

Microorganisms have coevolved diverse mechanisms to impair host defenses. A major one, superantigens, can result in devastating effects on the immune system. While all known superantigens induce vast immune cell proliferation and come from opportunistic pathogens, recently, proteins with similar broad specificity to antibody variable (V) domain families were identified in a commensal microbiota. These proteins, identified in the human commensal Ruminococcus gnavus, are called immunoglobulin-binding protein (Ibp) A and B and have been shown to activate B cells in vitro expressing either human VH3 or murine VH5/6/7. Here, we provide molecular and functional studies revealing the basis of this Ibp/immunoglobulin (Ig) interaction. The crystal structure and biochemical assays of a truncated IbpA construct in complex with mouse VH5 antigen-binding fragment (Fab) shows a binding of Ig heavy chain framework residues to the Ibp Domain D and the C-terminal heavy chain binding domain (HCBD). We used targeted mutagenesis of contact residues and affinity measurements and performed studies of the Fab-IbpA complex to determine the stoichiometry between Ibp and VH domains, suggesting Ibp may serve to cluster full-length IgA antibodies in vivo. Furthermore, in vitro stimulation experiments indicate that binding of the Ibp HCBD alone is sufficient to activate responsive murine B cell receptors. The presence of these proteins in a commensal microbe suggest that binding a broad repertoire of immunoglobulins, particularly in the gut/microbiome environment, may provide an important function in the maintenance of host/microbiome homeostasis contrasting with the pathogenic role of structurally homologous superantigens expressed by pathogens.

How Tim proteins differentially exploit membrane features to attain robust target sensitivity.

Immune surveillance cells such as T cells and phagocytes utilize integral plasma membrane receptors to recognize surface signatures on triggered and activated cells such as those in apoptosis. One such family of plasma membrane sensors, the transmembrane immunoglobulin and mucin domain (Tim) proteins, specifically recognize phosphatidylserine (PS) but elicit distinct immunological responses. The molecular basis for the recognition of lipid signals on target cell surfaces is not well understood. Previous results suggest that basic side chains present at the membrane interface on the Tim proteins might facilitate association with additional anionic lipids including but not necessarily limited to PS. We, therefore, performed a comparative quantitative analysis of the binding of the murine Tim1, Tim3, and Tim4, to synthetic anionic phospholipid membranes under physiologically relevant conditions. X-ray reflectivity and vesicle binding studies were used to compare the water-soluble domain of Tim3 with results previously obtained for Tim1 and Tim4. Although a calcium link was essential for all three proteins, the three homologs differed in how they balance the hydrophobic and electrostatic interactions driving membrane association. The proteins also varied in their sensing of phospholipid chain unsaturation and showed different degrees of cooperativity in their dependence on bilayer PS concentration. Surprisingly, trace amounts of anionic phosphatidic acid greatly strengthened the bilayer association of Tim3 and Tim4, but not Tim1. A novel mathematical model provided values for the binding parameters and illuminated the complex interplay among ligands. In conclusion, our results provide a quantitative description of the contrasting selectivity used by three Tim proteins in the recognition of phospholipids presented on target cell surfaces. This paradigm is generally applicable to the analysis of the binding of peripheral proteins to target membranes through the heterotropic cooperative interactions of multiple ligands.

Impact of a Workflow-Integrated Web Tool on Resource Utilization and Information-Seeking Behavior in an Academic Anesthesiology Department: Longitudinal Cohort Survey Study.

BACKGROUND: Medical resident reading and information-seeking behavior is limited by time constraints as well as comfort in accessing and assessing evidence-based resources. Educational technology interventions, as the preferred method for millennial leaners, can reduce these barriers. We implemented an educational web tool, consisting of peer-reviewed articles as well as local and national protocols and policies, built into the daily workflow of a university-based anesthesiology department. We hypothesized that this web tool would increase resource utilization and overall perceptions of the educational environment. OBJECTIVE: The goal of this study was to demonstrate that an educational web tool designed and built into the daily workflow of an academic anesthesia department for trainees could significantly decrease barriers to resource utilization, improve faculty-trainee teaching interactions, and improve the perceptions of the educational environment. METHODS: Following Institutional Review Board approval, a longitudinal cohort survey study was conducted to assess trainee resource utilization, faculty evaluation of trainees' resource utilization, and trainee and faculty perceptions about the educational environment. The survey study was conducted in a pre-post fashion 3 months prior to web tool implementation and 3 months following implementation. Data were deidentified and analyzed unpaired using Student t tests for continuous data and chi-square tests for ordinal data. RESULTS: Survey response rates were greater than 50% in all groups: of the 43 trainees, we obtained 27 (63%) preimplementation surveys and 22 (51%) postimplementation surveys; of the 46 faculty members, we obtained 25 (54%) preimplementation surveys and 23 (50%) postimplementation surveys. Trainees showed a significant improvement in utilization of peer-reviewed articles (preimplementation mean 8.67, SD 6.45; postimplementation mean 18.27, SD 12.23; P=.02), national guidelines (preimplementation mean 2.3, SD 2.40; postimplementation mean 6.14, SD 5.01; P<.001), and local policies and protocols (preimplementation mean 2.23, SD 2.72; postimplementation mean 6.95, SD 6.09; P=.02). There was significant improvement in faculty-trainee educational interactions (preimplementation mean 1.67, SD 1.33; postimplementation mean 6.05, SD 8.74; P=.01). Faculty assessment of trainee resource utilization also demonstrated statistically significant improvements across all resource categories. Subgroups among trainees and faculty showed similar trends toward improvement. CONCLUSIONS: Learning technology interventions significantly decrease the barriers to resource utilization, particularly among millennial learners. Further investigation has been undertaken to assess how this may impact learning, knowledge retention, and patient outcomes.

Molecular design of the γδT cell receptor ectodomain encodes biologically fit ligand recognition in the absence of mechanosensing.

High-acuity αßT cell receptor (TCR) recognition of peptides bound to major histocompatibility complex molecules (pMHCs) requires mechanosensing, a process whereby piconewton (pN) bioforces exert physical load on αßTCR-pMHC bonds to dynamically alter their lifetimes and foster digital sensitivity cellular signaling. While mechanotransduction is operative for both αßTCRs and pre-TCRs within the αßT lineage, its role in γδT cells is unknown. Here, we show that the human DP10.7 γδTCR specific for the sulfoglycolipid sulfatide bound to CD1d only sustains a significant load and undergoes force-induced structural transitions when the binding interface-distal γδ constant domain (C) module is replaced with that of αß. The chimeric γδ-αßTCR also signals more robustly than does the wild-type (WT) γδTCR, as revealed by RNA-sequencing (RNA-seq) analysis of TCR-transduced Rag2-/- thymocytes, consistent with structural, single-molecule, and molecular dynamics studies reflective of γδTCRs as mediating recognition via a more canonical immunoglobulin-like receptor interaction. Absence of robust, force-related catch bonds, as well as γδTCR structural transitions, implies that γδT cells do not use mechanosensing for ligand recognition. This distinction is consonant with the fact that their innate-type ligands, including markers of cellular stress, are expressed at a high copy number relative to the sparse pMHC ligands of αßT cells arrayed on activating target cells. We posit that mechanosensing emerged over ∼200 million years of vertebrate evolution to fulfill indispensable adaptive immune recognition requirements for pMHC in the αßT cell lineage that are unnecessary for the γδT cell lineage mechanism of non-pMHC ligand detection.

Altered selection on a single self-ligand promotes susceptibility to organ-specific T cell infiltration.

For the large array of self-peptide/MHC class II (pMHC-II) complexes displayed in the body, it is unclear whether CD4+ T cell tolerance must be imparted for each individual complex or whether pMHC-II-nonspecific bystander mechanisms are sufficient to confer tolerance by acting broadly on T cells reactive to multiple self-pMHC-II ligands. Here, via reconstitution of T cell-deficient mice, we demonstrate that altered T cell selection on a single prostate-specific self-pMHC-II ligand renders recipient mice susceptible to prostate-specific T cell infiltration. Mechanistically, this self-pMHC-II complex is required for directing antigen-specific cells into the Foxp3+ regulatory T cell lineage but does not induce clonal deletion to a measurable extent. Thus, our data demonstrate that polyclonal T reg cells are unable to functionally compensate for a breach in tolerance to a single self-pMHC-II complex in this setting, revealing vulnerabilities in antigen-nonspecific bystander mechanisms of immune tolerance.