Acute liver failure.

ABSTRACT: Acute liver failure, commonly caused by acetaminophen overdose, is associated with numerous systemic complications including cerebral edema, hypotension, acute kidney injury, and infection. Management is primarily supportive, with an emphasis on excellent neurocritical care. Although some antidotes and targeted treatments exist, the only definitive treatment remains orthotopic liver transplant.

Experimental Structures of Antibody/MHC-I Complexes Reveal Details of Epitopes Overlooked by Computational Prediction.

mAbs to MHC class I (MHC-I) molecules have proved to be crucial reagents for tissue typing and fundamental studies of immune recognition. To augment our understanding of epitopic sites seen by a set of anti-MHC-I mAb, we determined X-ray crystal structures of four complexes of anti-MHC-I Fabs bound to peptide/MHC-I/ß2-microglobulin (pMHC-I). An anti-H2-Dd mAb, two anti-MHC-I α3 domain mAbs, and an anti-ß2-microglobulin mAb bind pMHC-I at sites consistent with earlier mutational and functional experiments, and the structures explain allelomorph specificity. Comparison of the experimentally determined structures with computationally derived models using AlphaFold Multimer showed that although predictions of the individual pMHC-I heterodimers were quite acceptable, the computational models failed to properly identify the docking sites of the mAb on pMHC-I. The experimental and predicted structures provide insight into strengths and weaknesses of purely computational approaches and suggest areas that merit additional attention.

Experimental structures of antibody/MHC-I complexes reveal details of epitopes overlooked by computational prediction.

Monoclonal antibodies (mAb) to major histocompatibility complex class I (MHC-I) molecules have proved to be crucial reagents for tissue typing and fundamental studies of immune recognition. To augment our understanding of epitopic sites seen by a set of anti-MHC-I mAb, we determined X-ray crystal structures of four complexes of anti-MHC-I antigen-binding fragments (Fab) bound to peptide/MHC-I/ß2m (pMHC-I). An anti-H2-Dd mAb, two anti-MHC-I α3 domain mAb, and an anti-ß2-microglobulin (ß2m) mAb bind pMHC-I at sites consistent with earlier mutational and functional experiments, and the structures explain allelomorph specificity. Comparison of the experimentally determined structures with computationally derived models using AlphaFold Multimer (AF-M) showed that although predictions of the individual pMHC-I heterodimers were quite acceptable, the computational models failed to properly identify the docking sites of the mAb on pMHC-I. The experimental and predicted structures provide insight into strengths and weaknesses of purely computational approaches and suggest areas that merit additional attention.

SARS-CoV-2 antibodies recognize 23 distinct epitopic sites on the receptor binding domain.

The COVID-19 pandemic and SARS-CoV-2 variants have dramatically illustrated the need for a better understanding of antigen (epitope)-antibody (paratope) interactions. To gain insight into the immunogenic characteristics of epitopic sites (ES), we systematically investigated the structures of 340 Abs and 83 nanobodies (Nbs) complexed with the Receptor Binding Domain (RBD) of the SARS-CoV-2 spike protein. We identified 23 distinct ES on the RBD surface and determined the frequencies of amino acid usage in the corresponding CDR paratopes. We describe a clustering method for analysis of ES similarities that reveals binding motifs of the paratopes and that provides insights for vaccine design and therapies for SARS-CoV-2, as well as a broader understanding of the structural basis of Ab-protein antigen (Ag) interactions.

Chaperone function in antigen presentation by MHC class I molecules-tapasin in the PLC and TAPBPR beyond.

Peptide loading of MHC-I molecules plays a critical role in the T cell response to infections and tumors as well as to interactions with inhibitory receptors on natural killer (NK) cells. To facilitate and optimize peptide acquisition, vertebrates have evolved specialized chaperones to stabilize MHC-I molecules during their biosynthesis and to catalyze peptide exchange favoring high affinity or optimal peptides to permit transport to the cell surface where stable peptide/MHC-I (pMHC-I) complexes are displayed and are available for interaction with T cell receptors and any of a host of inhibitory and activating receptors. Although components of the endoplasmic reticulum (ER) resident peptide loading complex (PLC) were identified some 30 years ago, the detailed biophysical parameters that govern peptide selection, binding, and surface display have recently been understood better with advances in structural methods including X-ray crystallography, cryogenic electron microscopy (cryo-EM), and computational modeling. These approaches have provided refined mechanistic illustration of the molecular events involved in the folding of the MHC-I heavy chain, its coordinate glycosylation, assembly with its light chain, ß2-microglobulin (ß2m), its association with the PLC, and its binding of peptides. Our current view of this important cellular process as it relates to antigen presentation to CD8+ T cells is based on many different approaches: biochemical, genetic, structural, computational, cell biological, and immunological. In this review, taking advantage of recent X-ray and cryo-EM structural evidence and molecular dynamics simulations, examined in the context of past experiments, we attempt a dispassionate evaluation of the details of peptide loading in the MHC-I pathway. By critical evaluation of several decades of investigation, we outline aspects of the peptide loading process that are well-understood and indicate those that demand further detailed investigation. Further studies should contribute not only to basic understanding, but also to applications for immunization and therapy of tumors and infections.

SARS-CoV-2 antibodies recognize 23 distinct epitopic sites on the receptor binding domain.

The COVID-19 pandemic and SARS-CoV-2 variants have dramatically illustrated the need for a better understanding of antigen (epitope)-antibody (paratope) interactions. To gain insight into the immunogenic characteristics of epitopic sites (ES), we systematically investigated the structures of 340 Abs and 83 nanobodies (Nbs) complexed with the Receptor Binding Domain (RBD) of the SARS-CoV-2 spike protein. We identified 23 distinct ES on the RBD surface and determined the frequencies of amino acid usage in the corresponding CDR paratopes. We describe a clustering method for analysis of ES similarities that reveals binding motifs of the paratopes and that provides insights for vaccine design and therapies for SARS-CoV-2, as well as a broader understanding of the structural basis of Ab-protein antigen (Ag) interactions.

Associations of Community and Individual Social Determinants of Health With Medication Adherence in Patients With Atrial Fibrillation: A Retrospective Cohort Study.

Background Despite guideline-recommended use of oral anticoagulation (OAC) for stroke prevention in atrial fibrillation (AF), OAC medication adherence among patients with AF in the United States ranges from 47% to 82%. To characterize potential causes of nonadherence, we analyzed associations between community and individual social risk factors and OAC adherence for stroke prevention in AF. Methods and Results A retrospective cohort analysis of patients with AF was conducted using the IQVIA PharMetrics Plus claims data from January 2016 to June 2020, and 3-digit ZIP code-level social risk scores were calculated using American Community Survey and commercial data. Logistic regression models evaluated associations between community social determinants of health, community social risk scores for 5 domains (economic climate, food landscape, housing environment, transportation network, and health literacy), patient characteristics and comorbidities, and 2 adherence outcomes: persistence on OAC for 180 days and proportion of days covered ≥0.80 at 360 days. Of 28 779 patients with AF included in the study, 70.8% of patients were male, 94.6% were commercially insured, and the average patient age was 59.2 years. Multivariable regression found that greater health literacy risk was negatively associated with 180-day persistence (odds ratio [OR]=0.80 [95% CI, 0.76-0.83]) and 360-day proportion of days covered (OR, 0.81 [95% CI, 0.76-0.87]). Patient age and higher AF stroke risk score and AF bleeding risk scores were positively associated with both 180-day persistence and 360-day proportion of days covered. Conclusions Social risk domains, such as health literacy, may affect OAC adherence among patients with AF. Future studies should explore associations between social risk factors and nonadherence with greater geographic granularity.

Psychosocial Factors Associated with Lower Urinary Tract Symptoms One Year Postpartum.

Pregnancy carries substantial risk for developing lower urinary tract symptoms (LUTSs), with potential lifelong impacts on bladder health. Little is known about modifiable psychosocial factors that may influence the risk of postpartum LUTSs. We examined associations between depressive symptoms, perceived stress, and postpartum LUTSs, and the moderating effects of perceived social support, using data from a cohort study of Expect With Me group prenatal care (n = 462). One year postpartum, 40.3% participants reported one or more LUTS. The most frequent LUTS was daytime frequency (22.3%), followed by urinary incontinence (19.5%), urgency (18.0%), nocturia (15.6%), and bladder pain (6.9%). Higher odds of any LUTS were associated with greater depressive symptoms (adjusted odds ratio (AOR) 1.08, 95% confidence interval (CI) 1.04-1.11) and perceived stress (AOR 1.12, 95% CI 1.04-1.19). Higher perceived social support was associated with lower odds of any LUTS (AOR 0.94, 95% CI 0.88-0.99). Perceived social support mitigated the adverse effects of depressive symptoms (interaction AOR 0.99, 95% CI 0.98-0.99) and perceived stress (interaction AOR 0.97, 95% CI 0.95-0.99) on experiencing any LUTS. Greater depressive symptoms and perceived stress may increase the likelihood of experiencing LUTSs after childbirth. Efforts to promote bladder health among postpartum patients should consider psychological factors and social support.

Potent monoclonal antibodies neutralize Omicron sublineages and other SARS-CoV-2 variants.

The emergence and global spread of the SARS-CoV-2 Omicron variants, which carry an unprecedented number of mutations, raise serious concerns due to the reduced efficacy of current vaccines and resistance to therapeutic antibodies. Here, we report the generation and characterization of two potent human monoclonal antibodies, NA8 and NE12, against the receptor-binding domain of the SARS-CoV-2 spike protein. NA8 interacts with a highly conserved region and has a breadth of neutralization with picomolar potency against the Beta variant and the Omicron BA.1 and BA.2 sublineages and nanomolar potency against BA.2.12.1 and BA.4. Combination of NA8 and NE12 retains potent neutralizing activity against the major SARS-CoV-2 variants of concern. Cryo-EM analysis provides the structural basis for the broad and complementary neutralizing activity of these two antibodies. We confirm the in vivo protective and therapeutic efficacies of NA8 and NE12 in the hamster model. These results show that broad and potent human antibodies can overcome the continuous immune escape of evolving SARS-CoV-2 variants.

Structural mechanism of tapasin-mediated MHC-I peptide loading in antigen presentation.

Loading of MHC-I molecules with peptide by the catalytic chaperone tapasin in the peptide loading complex plays a critical role in antigen presentation and immune recognition. Mechanistic insight has been hampered by the lack of detailed structural information concerning tapasin-MHC-I. We present here crystal structures of human tapasin complexed with the MHC-I molecule HLA-B*44:05, and with each of two anti-tapasin antibodies. The tapasin-stabilized peptide-receptive state of HLA-B*44:05 is characterized by distortion of the peptide binding groove and destabilization of the ß2-microglobulin interaction, leading to release of peptide. Movements of the membrane proximal Ig-like domains of tapasin, HLA-B*44:05, and ß2-microglobulin accompany the transition to a peptide-receptive state. Together this ensemble of crystal structures provides insights into a distinct mechanism of tapasin-mediated peptide exchange.

Chaperones and Catalysts: How Antigen Presentation Pathways Cope With Biological Necessity.

Immune recognition by T lymphocytes and natural killer (NK) cells is in large part dependent on the identification of cell surface MHC molecules bearing peptides generated from either endogenous (MHC I) or exogenous (MHC II) dependent pathways. This review focuses on MHC I molecules that coordinately fold to bind self or foreign peptides for such surface display. Peptide loading occurs in an antigen presentation pathway that includes either the multimolecular peptide loading complex (PLC) or a single chain chaperone/catalyst, TAP binding protein, related, TAPBPR, that mimics a key component of the PLC, tapasin. Recent structural and dynamic studies of TAPBPR reveal details of its function and reflect on mechanisms common to tapasin. Regions of structural conservation among species suggest that TAPBPR and tapasin have evolved to satisfy functional complexities demanded by the enormous polymorphism of MHC I molecules. Recent studies suggest that these two chaperone/catalysts exploit structural flexibility and dynamics to stabilize MHC molecules and facilitate peptide loading.

Extremely potent monoclonal antibodies neutralize Omicron and other SARS-CoV-2 variants.

The ongoing coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has triggered a devastating global health, social and economic crisis. The RNA nature and broad circulation of this virus facilitate the accumulation of mutations, leading to the continuous emergence of variants of concern with increased transmissibility or pathogenicity 1 . This poses a major challenge to the effectiveness of current vaccines and therapeutic antibodies 1, 2 . Thus, there is an urgent need for effective therapeutic and preventive measures with a broad spectrum of action, especially against variants with an unparalleled number of mutations such as the recently emerged Omicron variant, which is rapidly spreading across the globe 3 . Here, we used combinatorial antibody phage-display libraries from convalescent COVID-19 patients to generate monoclonal antibodies against the receptor-binding domain of the SARS-CoV-2 spike protein with ultrapotent neutralizing activity. One such antibody, NE12, neutralizes an early isolate, the WA-1 strain, as well as the Alpha and Delta variants with half-maximal inhibitory concentrations at picomolar level. A second antibody, NA8, has an unusual breadth of neutralization, with picomolar activity against both the Beta and Omicron variants. The prophylactic and therapeutic efficacy of NE12 and NA8 was confirmed in preclinical studies in the golden Syrian hamster model. Analysis by cryo-EM illustrated the structural basis for the neutralization properties of NE12 and NA8. Potent and broadly neutralizing antibodies against conserved regions of the SARS-CoV-2 spike protein may play a key role against future variants of concern that evade immune control.

Features and Impact of Trust-Based Relationships Between Community Health Workers and Low-Resource Perinatal Women with Chronic Health Conditions.

OBJECTIVES: Community health worker (CHW) programs are a promising strategy to improve maternal and child health outcomes, particularly among low-resource women. Yet, little is known about which aspects of CHW-client relationships are most salient for promoting positive change. This paper examines features of the CHW-client relationship that perinatal women with chronic conditions reported as being beneficial for their experience of prenatal care and pregnancy. METHODS: Focus groups and interviews were conducted with 18 CHWs and 39 clients from three Merck for Mothers-funded programs in the Eastern United States. Data were analyzed using a grounded theory-informed thematic approach. RESULTS: CHWs built trust-based relationships through emotional attendance, authenticity, and prioritization of clients' needs. They provided instrumental, informational, and emotional support that clients reported facilitated greater engagement with the healthcare system, improved health behaviors, and reduced stress. CHWs and clients alike viewed their relationships as having long-lasting impacts, made possible by the trust-based bond between them. DISCUSSION: Strong, trusting relationships with CHWs may be one avenue through which to improve maternal and infant health for vulnerable perinatal women. Community health care programs should promote trust-building as an explicit program goal. Trust-based CHW-client relationships may serve as an exemplar for transforming traditional care relationships between providers and clients, leading to greater client engagement in care and improved health.

Structures of synthetic nanobody-SARS-CoV-2 receptor-binding domain complexes reveal distinct sites of interaction.

Combating the worldwide spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the emergence of new variants demands understanding of the structural basis of the interaction of antibodies with the SARS-CoV-2 receptor-binding domain (RBD). Here, we report five X-ray crystal structures of sybodies (synthetic nanobodies) including those of binary and ternary complexes of Sb16-RBD, Sb45-RBD, Sb14-RBD-Sb68, and Sb45-RBD-Sb68, as well as unliganded Sb16. These structures reveal that Sb14, Sb16, and Sb45 bind the RBD at the angiotensin-converting enzyme 2 interface and that the Sb16 interaction is accompanied by a large conformational adjustment of complementarity-determining region 2. In contrast, Sb68 interacts at the periphery of the SARS-CoV-2 RBD-angiotensin-converting enzyme 2 interface. We also determined cryo-EM structures of Sb45 bound to the SARS-CoV-2 spike protein. Superposition of the X-ray structures of sybodies onto the trimeric spike protein cryo-EM map indicates that some sybodies may bind in both "up" and "down" configurations, but others may not. Differences in sybody recognition of several recently identified RBD variants are explained by these structures.

Structures of synthetic nanobody-SARS-CoV-2-RBD complexes reveal distinct sites of interaction and recognition of variants.

The worldwide spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and emergence of new variants demands understanding the structural basis of the interaction of antibodies with the SARS-CoV-2 receptor-binding domain (RBD). Here we report five X-ray crystal structures of sybodies (synthetic nanobodies) including binary and ternary complexes of Sb16-RBD, Sb45-RBD, Sb14-RBD-Sb68, and Sb45-RBD-Sb68; and Sb16 unliganded. These reveal that Sb14, Sb16, and Sb45 bind the RBD at the ACE2 interface and that the Sb16 interaction is accompanied by a large CDR2 shift. In contrast, Sb68 interacts at the periphery of the interface. We also determined cryo-EM structures of Sb45 bound to spike (S). Superposition of the X-ray structures of sybodies onto the trimeric S protein cryo-EM map indicates some may bind both "up" and "down" configurations, but others may not. Sensitivity of sybody binding to several recently identified RBD mutants is consistent with these structures.

A local regulatory T cell feedback circuit maintains immune homeostasis by pruning self-activated T cells.

A fraction of mature T cells can be activated by peripheral self-antigens, potentially eliciting host autoimmunity. We investigated homeostatic control of self-activated T cells within unperturbed tissue environments by combining high-resolution multiplexed and volumetric imaging with computational modeling. In lymph nodes, self-activated T cells produced interleukin (IL)-2, which enhanced local regulatory T cell (Treg) proliferation and inhibitory functionality. The resulting micro-domains reciprocally constrained inputs required for damaging effector responses, including CD28 co-stimulation and IL-2 signaling, constituting a negative feedback circuit. Due to these local constraints, self-activated T cells underwent transient clonal expansion, followed by rapid death ("pruning"). Computational simulations and experimental manipulations revealed the feedback machinery's quantitative limits: modest reductions in Treg micro-domain density or functionality produced non-linear breakdowns in control, enabling self-activated T cells to subvert pruning. This fine-tuned, paracrine feedback process not only enforces immune homeostasis but also establishes a sharp boundary between autoimmune and host-protective T cell responses.

Synthetic nanobody-SARS-CoV-2 receptor-binding domain structures identify distinct epitopes.

The worldwide spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) demands unprecedented attention. We report four X-ray crystal structures of three synthetic nanobodies (sybodies) (Sb16, Sb45 and Sb68) bind to the receptor-binding domain (RBD) of SARS-CoV-2: binary complexes of Sb16-RBD and Sb45-RBD; a ternary complex of Sb45-RBD-Sb68; and Sb16 unliganded. Sb16 and Sb45 bind the RBD at the ACE2 interface, positioning their CDR2 and CDR3 loops diametrically. Sb16 reveals a large CDR2 shift when binding the RBD. Sb68 interacts peripherally at the ACE2 interface; steric clashes with glycans explain its mechanism of viral neutralization. Superposing these structures onto trimeric spike (S) protein models indicates these sybodies bind conformations of the mature S protein differently, which may aid therapeutic design. ONE SENTENCE SUMMARY: X-ray structures of synthetic nanobodies complexed with the receptor-binding domain of the spike protein of SARS-CoV-2 reveal details of CDR loop interactions in recognition of distinct epitopic sites.

Effectiveness in adapting the implementation of the Early Care and Education Learning Collaboratives Project (ECELC) using real-world conditions.

The National Early Care and Education Learning Collaboratives Project (ECELC) was a multistate intervention that was highly effective in implementing best practices for healthy eating physical activity (HEPA) in early care and education (ECE) programs across the USA. The ECELC included didactic in-person learning sessions, technical assistance, and self-assessment-guided action planning. This study aimed to describe the effectiveness of adaptions to the self-assessments, learning sessions, and overall support, and also aimed to compare the effectiveness of each to the Original ECELC Model, when applicable. This study utilized a pre-poststudy design using data collected via the Nutrition and Physical Activity Self-Assessment for Child Care (NAP SACC) instrument for ECE programs that adapted the Original ECELC Model. Adaptations to the Original ECELC Model were found to promote best practices and policies with regard to Breastfeeding & Infant Feeding, Child Nutrition, Infant & Child Physical Activity, Outdoor Play & Learning, and/or Screen Time as demonstrated by the NAP SACC (p < .05), with some exceptions of nonstatistically significant increases. Improvements were found to be statistically similar to improvements made among participants of the Original ECELC Model. Partner-driven, scalable, and customizable policy- and practice-based interventions to promote HEPA among children in ECE settings may serve as a key strategy to work toward reducing risk for childhood obesity.

Black Pregnant Women "Get the Most Judgment": A Qualitative Study of the Experiences of Black Women at the Intersection of Race, Gender, and Pregnancy.

BACKGROUND: Pronounced racial disparities in maternal and infant health outcomes persist in the United States. Using an ecosocial and intersectionality framework and biopsychosocial model of health, we aimed to understand Black pregnant women's experiences of gendered racism during pregnancy. METHODS: We conducted semistructured interviews with 24 Black pregnant women in New Haven, Connecticut. We asked women about their experience of being pregnant, experiences of gendered racism, and concerns related to pregnancy and parenting Black children. Transcripts were coded by three trained analysts using grounded theory techniques. RESULTS: Women experienced gendered racism during pregnancy-racialized pregnancy stigma-in the form of stereotypes stigmatizing Black motherhood that devalued Black pregnancies. Women reported encountering assumptions that they had low incomes, were single, and had multiple children, regardless of socioeconomic status, marital status, or parity. Women encountered racialized pregnancy stigma in everyday, health care, social services, and housing-related contexts, making it difficult to complete tasks without scrutiny. For many, racialized pregnancy stigma was a source of stress. To counteract these stereotypes, women used a variety of coping responses, including positive self-definition. CONCLUSIONS: Racialized pregnancy stigma may contribute to poorer maternal and infant outcomes by way of reduced access to quality health care; impediments to services, resources, and social support; and poorer psychological health. Interventions to address racialized pregnancy stigma and its adverse consequences include anti-bias training for health care and social service providers; screening for racialized pregnancy stigma and providing evidence-based coping strategies; creating pregnancy support groups; and developing a broader societal discourse that values Black women and their pregnancies.

Considerations for Building Sustainable Community Health Worker Programs to Improve Maternal Health.

OBJECTIVES: Community health workers (CHWs) are a critical part of the healthcare workforce and valuable members of healthcare teams. However, little is known about successful strategies for sustaining CHW programs. The aim of this study is to identify institutional and community factors that may contribute to the sustainability of CHW programs to improve maternal health outcomes. METHODS: We conducted focus groups and in-depth interviews with 54 CHWs, CHW program staff, and community partners involved in implementing three Merck for Mothers-funded CHW programs in the United States serving reproductive-age women with chronic health conditions. Additionally, a review of documents submitted by CHW programs during the evaluation process provided context for our findings. Data were analyzed using an inductive qualitative approach. RESULTS: Three themes emerged in our analysis of factors that may influence the sustainability of CHW programs to improve maternal health: CHW support from supervisors, providers, and peers; relationships with healthcare systems and insurers; and securing adequate, continuous funding. Key findings include the need for CHWs to have strong supervisory structures, participate in regular care team meetings, and interact with peers; advantages of CHWs having access to electronic health records; and importance of full-cost accounting and developing a broad base of financial support for CHW programs. CONCLUSION: Research should continue to identify best practices for implementation of such programs, particularly regarding effective supervisory support structures, integration of programs with healthcare systems, and long-term revenue streams.