Multiple severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants that have mutations associated with increased transmission and antibody escape have arisen over the course of the ...current pandemic. Although the current vaccines have largely been effective against past variants, the number of mutations found on the Omicron (B.1.1.529) spike protein appear to diminish the protection conferred by preexisting immunity. Using vesicular stomatitis virus (VSV) pseudoparticles expressing the spike protein of several SARS-CoV-2 variants, we evaluated the magnitude and breadth of the neutralizing antibody response over time in individuals after infection and in mRNA-vaccinated individuals. We observed that boosting increases the magnitude of the antibody response to wild-type (D614), Beta, Delta, and Omicron variants; however, the Omicron variant was the most resistant to neutralization. We further observed that vaccinated healthy adults had robust and broad antibody responses, whereas responses may have been reduced in vaccinated pregnant women, underscoring the importance of learning how to maximize mRNA vaccine responses in pregnant populations. Findings from this study show substantial heterogeneity in the magnitude and breadth of responses after infection and mRNA vaccination and may support the addition of more conserved viral antigens to existing SARS-CoV-2 vaccines.
Monoclonal antibodies show efficacy in treating COVID-19, but the functional requirements for protection are unclear. In this issue of Immunity, Ullah et al. (2021) develop a stable SARS-CoV-2 ...reporter virus and use bioluminescence imaging to longitudinally monitor infection and assess neutralizing monoclonal antibody interventions in mice. They find that antibody-mediated protection depends on the Fc domain and Fc-gamma receptor-expressing immune cells.
Monoclonal antibodies show efficacy in treating COVID-19, but the functional requirements for protection are unclear. In this issue of Immunity, Ullah et al. (2021) develop a stable SARS-CoV-2 reporter virus and use bioluminescence imaging to longitudinally monitor infection and assess neutralizing monoclonal antibody interventions in mice. They find that antibody-mediated protection depends on the Fc domain and Fc-gamma receptor-expressing immune cells.
In this review, we discuss how IgG antibodies can modulate inflammatory signaling during viral infections with a focus on CD16a‐mediated functions. We describe the structural heterogeneity of IgG ...antibody ligands, including subclass and glycosylation that impact binding by and downstream activity of CD16a, as well as the heterogeneity of CD16a itself, including allele and expression density. While inflammation is a mechanism required for immune homeostasis and resolution of acute infections, we focus here on two infectious diseases that are driven by pathogenic inflammatory responses during infection. Specifically, we review and discuss the evolving body of literature showing that afucosylated IgG immune complex signaling through CD16a contributes to the overwhelming inflammatory response that is central to the pathogenesis of severe forms of dengue disease and coronavirus disease 2019 (COVID‐19).
The effector activity of IgG antibodies is regulated at several levels, including IgG subclass, modifications of the Fc glycan, and the distribution of Type I and II Fcγ receptors (FcγR) on effector ...cells. Here, we explore how Fc glycosylation, particularly sialylation and fucosylation, tunes cellular responses to immune complexes. We review the current understanding of the pathways and mechanisms underlying this biology, address FcγR in antigen presentation, and discuss aspects of the clinical understanding of Fc glycans in therapies and disease.
A damaging inflammatory response is implicated in the pathogenesis of severe coronavirus disease 2019 (COVID-19), but mechanisms contributing to this response are unclear. In two prospective cohorts, ...early non-neutralizing, afucosylated immunoglobulin G (IgG) antibodies specific to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) were associated with progression from mild to more severe COVID-19. To study the biology of afucosylated IgG immune complexes, we developed an in vivo model that revealed that human IgG-Fc-gamma receptor (FcγR) interactions could regulate inflammation in the lung. Afucosylated IgG immune complexes isolated from patients with COVID-19 induced inflammatory cytokine production and robust infiltration of the lung by immune cells. In contrast to the antibody structures that were associated with disease progression, antibodies that were elicited by messenger RNA SARS-CoV-2 vaccines were highly fucosylated and enriched in sialylation, both modifications that reduce the inflammatory potential of IgG. Vaccine-elicited IgG did not promote an inflammatory lung response. These results show that human IgG-FcγR interactions regulate inflammation in the lung and define distinct lung activities mediated by the IgG that are associated with protection against, or progression to, severe COVID-19.
Duchenne muscular dystrophy (DMD) is a severe muscle wasting disease caused by the lack of dystrophin. Heart failure, driven by cardiomyocyte death, fibrosis, and the development of dilated ...cardiomyopathy, is the leading cause of death in DMD patients. Current treatments decrease the mechanical load on the heart but do not address the root cause of dilated cardiomyopathy: cardiomyocyte death. Previously, we showed that telomere shortening is a hallmark of DMD cardiomyocytes. Here, we test whether prevention of telomere attrition is possible in cardiomyocytes differentiated from patient-derived induced pluripotent stem cells (iPSC-CMs) and if preventing telomere shortening impacts cardiomyocyte function. We observe reduced cell size, nuclear size, and sarcomere density in DMD iPSC-CMs compared with healthy isogenic controls. We find that expression of just one telomere-binding protein, telomeric repeat-binding factor 2 (TRF2), a core component of the shelterin complex, prevents telomere attrition and rescues deficiencies in cell size as well as sarcomere density. We employ a bioengineered platform to micropattern cardiomyocytes for calcium imaging and perform Southern blots of telomere restriction fragments, the gold standard for telomere length assessments. Importantly, preservation of telomere lengths in DMD cardiomyocytes improves their viability. These data provide evidence that preventing telomere attrition ameliorates deficits in cell morphology, activation of the DNA damage response, and premature cell death, suggesting that TRF2 is a key player in DMD-associated cardiac failure.
Structural analysis of a known apoptosis signal-regulating kinase 1 (ASK1) inhibitor bound to its kinase domain led to the design and synthesis of the novel macrocyclic inhibitor 8 (cell IC50 = 1.2 ...μM). The profile of this compound was optimized for CNS penetration following two independent strategies: a rational design approach leading to 19 and a parallel synthesis approach leading to 26. Both analogs are potent ASK1 inhibitors in biochemical and cellular assays (19, cell IC50 = 95 nM; 26, cell IC50 = 123 nM) and have moderate to low efflux ratio (ER) in an MDR1-MDCK assay (19, ER = 5.2; 26, ER = 1.5). In vivo PK studies revealed that inhibitor 19 had moderate CNS penetration (K puu = 0.17) and analog 26 had high CNS penetration (K puu = 1.0).
Motivated behaviors are often studied in isolation to assess labeled lines of neural connections underlying innate actions. However, in nature, multiple systems compete for expression of ...goal-directed behaviors via complex neural networks. Here, we examined flexible survival decisions in animals tasked with food seeking under predation threat. We found that predator exposure rapidly induced physiological, neuronal, and behavioral adaptations in mice highlighted by reduced food seeking and consumption contingent on current threat level. Diminishing conflict via internal state or external environment perturbations shifted feeding strategies. Predator introduction and/or selective manipulation of danger-responsive cholecystokinin (Cck) cells of the dorsal premammilary nucleus (PMd) suppressed hunger-sensitive Agouti-related peptide (AgRP) neurons, providing a mechanism for threat-evoked hypophagia. Increased caloric need enhanced food seeking under duress through AgRP pathways to the bed nucleus of the stria terminalis (BNST) and/or lateral hypothalamus (LH). Our results suggest oscillating interactions between systems underlying self-preservation and food seeking to promote optimal behavior.
•Predator exposure induced physiological/behavioral changes contingent on threat level•Diminishing conflict via internal or external perturbations shifted feeding strategies•Predator addition or PMdCck activation inhibited AgRP neurons, resulting in hypophagia•Increased caloric need via AgRP → BNST and/or LH enhanced food seeking under predation
Motivated behaviors are often studied in a behavioral vacuum for experimental simplicity. However, in nature, systems compete in real time for expression of goal-directed behaviors via complex neural networks. Here, de Araujo Salgado et al. examine flexible behaviors used by animals tasked with food seeking under predation threat and uncover a neural mechanism of how these systems interact to maximize survival.
Resident valvular interstitial cells (VICs) activate to myofibroblasts during aortic valve stenosis progression, which further promotes fibrosis or even differentiate into osteoblast-like cells that ...can lead to calcification of valve tissue. Inflammation is a hallmark of aortic valve stenosis, so we aimed to determine proinflammatory cytokines secreted from M1 macrophages that give rise to a transient VIC phenotype that leads to calcification of valve tissue. Approach and Results: We designed hydrogel biomaterials as valve extracellular matrix mimics enabling the culture of VICs in either their quiescent fibroblast or activated myofibroblast phenotype in response to the local matrix stiffness. When VIC fibroblasts and myofibroblasts were treated with conditioned media from THP-1-derived M1 macrophages, we observed robust reduction of αSMA (alpha smooth muscle actin) expression, reduced stress fiber formation, and increased proliferation, suggesting a potent antifibrotic effect. We further identified TNF (tumor necrosis factor)-α and IL (interleukin)-1β as 2 cytokines in M1 media that cause the observed antifibrotic effect. After 7 days of culture in M1 conditioned media, VICs began differentiating into osteoblast-like cells, as measured by increased expression of RUNX2 (runt-related transcription factor 2) and osteopontin. We also identified and validated IL-6 as a critical mediator of the observed pro-osteogenic effect.
Proinflammatory cytokines in M1 conditioned media inhibit myofibroblast activation in VICs (eg, TNF-α and IL-1β) and promote their osteogenic differentiation (eg, IL-6). Together, our work suggests inflammatory M1 macrophages may drive a myofibroblast-to-osteogenic intermediate VIC phenotype, which may mediate the switch from fibrosis to calcification during aortic valve stenosis progression.
Purpose Bladder plasmacytoid carcinoma is an invasive urothelial carcinoma subtype that is emphasized for its morphological overlap with plasma cells and metastatic carcinoma. Our experience suggests ...frequent intraperitoneal spread that is not typical of conventional urothelial carcinoma. Materials and Methods We identified cases of plasmacytoid urothelial carcinoma diagnosed on radical cystectomy. Patient age, gender, American Joint Committee on Cancer (7th edition) stage, metastatic spread/recurrence sites and clinical disease status at last followup were recorded. Results A total of 10 male and 5 female patients 42 to 81 years old were identified. One tumor was pT2, 11 pT3 and 3 pT4. Six of 15 patients (40%) presented with lymph node metastasis and 5 (33%) had intraperitoneal metastasis at cystectomy. These initial sites of metastatic spread included the prerectal space, ovary and vagina, ovary and fallopian tube, bowel serosa, and omentum and bowel serosa in 1 case each. Three patients had subsequent metastasis involving the prerectal space, pleural fluid and small bowel serosa, and bowel serosa in 1 each. Eight patients had followup information available, including 3 who died of disease, 3 with disease and 2 with no evidence of disease. Conclusions Of the patients 33% with the plasmacytoid variant of urothelial carcinoma presented with intraperitoneal disease spread and 20% had subsequent metastasis involving serosal surfaces. The possibility of noncontiguous intraperitoneal spread involving serosal surfaces should be recognized to ensure proper intraoperative staging and clinical followup for patients with plasmacytoid carcinoma.
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