Glycomics of cervicovaginal fluid from women at risk of preterm birth reveals immuno-regulatory epitopes that are hallmarks of cancer and viral glycosylation.

During pregnancy the immune system needs to maintain immune tolerance of the foetus while also responding to infection, which can cause premature activation of the inflammatory pathways leading to the onset of labour and preterm birth. The vaginal microbiome is an important modifier of preterm birth risk, with Lactobacillus dominance during pregnancy associated with term delivery while high microbial diversity is associated with an increased risk of preterm birth. Glycans on glycoproteins along the lower female reproductive tract are fundamental to microbiota-host interactions and the mediation of inflammatory responses. However, the specific glycan epitopes involved in these processes are not well understood. To address this, we conducted glycomic analyses of cervicovaginal fluid (CVF) from 36 pregnant women at high risk of preterm birth and 4 non-pregnant women. Our analysis of N- and O-glycans revealed a rich CVF glycome. While O-glycans were shown to be the main carriers of ABO blood group epitopes, the main features of N-glycans were the presence of abundant paucimannose and high mannose glycans, and a remarkable diversity of complex bi-, tri-, and tetra-antennary glycans decorated with fucose and sialic acid. We identified immuno-regulatory epitopes, such as Lewis antigens, and found that fucosylation was negatively correlated to pro-inflammatory factors, such as IL-1ß, MMP-8, C3a and C5a, while glycans with only sialylated antennae were mainly positively correlated to those. Similarly, paucimannose glycans showed a positive correlation to pro-inflammatory factors. We revealed a high abundance of glycans which have previously been identified as hallmarks of cancer and viral glycosylation, such as Man8 and Man9 high mannose glycans. Although each pregnant woman had a unique glycomic profile, longitudinal studies showed that the main glycosylation features were consistent throughout pregnancy in women who delivered at term, whereas women who experienced extreme preterm birth exhibited sharp changes in the CVF glycome shortly before delivery. These findings shed light on the processes underlying the role of glycosylation in maintaining a healthy vaginal microbiome and associated host immune responses. In addition, these discoveries facilitate our understanding of the lower female reproductive tract which has broad implications for women's health.

Exercise-specific adaptations in human skeletal muscle: Molecular mechanisms of making muscles fit and mighty.

The mechanisms leading to a predominantly hypertrophied phenotype versus a predominantly oxidative phenotype, the hallmarks of resistance training (RT) or aerobic training (AT), respectively, are being unraveled. In humans, exposure of naïve persons to either AT or RT results in their skeletal muscle exhibiting generic 'exercise stress-related' signaling, transcription, and translation responses. However, with increasing engagement in AT or RT, the responses become refined, and the phenotype typically associated with each form of exercise emerges. Here, we review some of the mechanisms underpinning the adaptations of how muscles become, through AT, 'fit' and RT, 'mighty.' Much of our understanding of molecular exercise physiology has arisen from targeted analysis of post-translational modifications and measures of protein synthesis. Phosphorylation of specific residue sites has been a dominant focus, with canonical signaling pathways (AMPK and mTOR) studied extensively in the context of AT and RT, respectively. These alone, along with protein synthesis, have only begun to elucidate key differences in AT and RT signaling. Still, key yet uncharacterized differences exist in signaling and regulation of protein synthesis that drive unique adaptation to AT and RT. Omic studies are required to better understand the divergent relationship between exercise and phenotypic outcomes of training.

Mitigating disuse-induced skeletal muscle atrophy in ageing: Resistance exercise as a critical countermeasure.

The gradual deterioration of physiological systems with ageing makes it difficult to maintain skeletal muscle mass (sarcopenia), at least partly due to the presence of 'anabolic resistance', resulting in muscle loss. Sarcopenia can be transiently but markedly accelerated through periods of muscle disuse-induced (i.e., unloading) atrophy due to reduced physical activity, sickness, immobilisation or hospitalisation. Periods of disuse are detrimental to older adults' overall quality of life and substantially increase their risk of falls, physical and social dependence, and early mortality. Disuse events induce skeletal muscle atrophy through various mechanisms, including anabolic resistance, inflammation, disturbed proteostasis and mitochondrial dysfunction, all of which tip the scales in favour of a negative net protein balance and subsequent muscle loss. Concerningly, recovery from disuse atrophy is more difficult for older adults than their younger counterparts. Resistance training (RT) is a potent anabolic stimulus that can robustly stimulate muscle protein synthesis and mitigate muscle losses in older adults when implemented before, during and following unloading. RT may take the form of traditional weightlifting-focused RT, bodyweight training and lower- and higher-load RT. When combined with sufficient dietary protein, RT can accelerate older adults' recovery from a disuse event, mitigate frailty and improve mobility; however, few older adults regularly participate in RT. A feasible and practical approach to improving the accessibility and acceptability of RT is through the use of resistance bands. Moving forward, RT must be prescribed to older adults to mitigate the negative consequences of disuse atrophy.

Generative Pre-trained Transformer for Pediatric Stroke Research: A Pilot Study.

BACKGROUND: Pediatric stroke is an important cause of morbidity in children. Although research can be challenging, large amounts of data have been captured through collaborative efforts in the International Pediatric Stroke Study (IPSS). This study explores the use of an advanced artificial intelligence program, the Generative Pre-trained Transformer (GPT), to enter pediatric stroke data into the IPSS. METHODS: The most recent 50 clinical notes of patients with ischemic stroke or cerebral venous sinus thrombosis at the UTHealth Pediatric Stroke Clinic were deidentified. Domain-specific prompts were engineered for an offline artificial intelligence program (GPT) to answer IPSS questions. Responses from GPT were compared with the human rater. Percent agreement was assessed across 50 patients for each of the 114 queries developed from the IPSS database outcome questionnaire. RESULTS: GPT demonstrated strong performance on several questions but showed variability overall. In its early iterations it was able to match human judgment occasionally with an accuracy score of 1.00 (n = 20, 17.5%), but it scored as low as 0.26 in some patients. Prompts were adjusted in four subsequent iterations to increase accuracy. In its fourth iteration, agreement was 93.6%, with a maximum agreement of 100% and minimum of 62%. Of 2400 individual items assessed, our model entered 2247 (93.6%) correctly and 153 (6.4%) incorrectly. CONCLUSIONS: Although our tailored generative model with domain-specific prompt engineering and ontological guidance shows promise for research applications, further refinement is needed to enhance its accuracy. It cannot enter data entirely independently, but it can be employed in tandem with human oversight contributing to a collaborative approach that reduces overall effort.

Cellular heterogeneity of pluripotent stem cell-derived cardiomyocyte grafts is mechanistically linked to treatable arrhythmias.

Preclinical data have confirmed that human pluripotent stem cell-derived cardiomyocytes (PSC-CMs) can remuscularize the injured or diseased heart, with several clinical trials now in planning or recruitment stages. However, because ventricular arrhythmias represent a complication following engraftment of intramyocardially injected PSC-CMs, it is necessary to provide treatment strategies to control or prevent engraftment arrhythmias (EAs). Here, we show in a porcine model of myocardial infarction and PSC-CM transplantation that EAs are mechanistically linked to cellular heterogeneity in the input PSC-CM and resultant graft. Specifically, we identify atrial and pacemaker-like cardiomyocytes as culprit arrhythmogenic subpopulations. Two unique surface marker signatures, signal regulatory protein α (SIRPA)+CD90-CD200+ and SIRPA+CD90-CD200-, identify arrhythmogenic and non-arrhythmogenic cardiomyocytes, respectively. Our data suggest that modifications to current PSC-CM-production and/or PSC-CM-selection protocols could potentially prevent EAs. We further show that pharmacologic and interventional anti-arrhythmic strategies can control and potentially abolish these arrhythmias.

How Better Health Strategies Could Reduce Juvenile Crime.

This JAMA Forum discusses health strategies that could be used to reduce juvenile crime, including identifying and treating trauma with behavioral health, rethinking the punishment approach, and incorporating other methods to overcome current challenges.

Hormones, Hypertrophy, and Hype: An Evidence-Guided Primer on Endogenous Endocrine Influences on Exercise-Induced Muscle Hypertrophy.

We review the evidence indicating that endogenous changes in these hormones, including testosterone, growth hormone, insulin growth factor-1, and estrogen, and their proposed anabolic effects contribute to and augment resistance exercise training (RET)-induced hypertrophy. Additionally, we provide recommendations for gold-standard methodological rigor to establish best practices for verifying menstrual phases as part of their research, ultimately enhancing our understanding of the impact of ovarian hormones on RET-induced adaptations.

Sustained Reduction of Elevated Intact Parathyroid Hormone Concentrations with Extended-release Calcifediol Slows Chronic Kidney Disease Progression in Secondary Hyperparathyroidism Patients.

INTRODUCTION: Chronic kidney disease (CKD) drives onerous human and healthcare costs, underscoring an urgent need to avert disease progression. Secondary hyperparathyroidism (SHPT) develops as CKD advances, and persistently elevated parathyroid hormone (PTH) may be nephrotoxic and associated with earlier dialysis onset. This study examines, for the first time, the hypothesis that sustained reduction of elevated intact PTH (iPTH) with extended-release calcifediol (ERC) reduces the nephrotoxic impact of SHPT and forestalls renal decline. METHODS: Changes in estimated glomerular filtration rate (eGFR) were analyzed post-hoc in 126 adults with SHPT, stage 3-4 CKD and low serum 25-hydroxyvitamin D (25D) treated for one year with ERC in pivotal trials. ERC was administered at 30 µg/day increasing, as needed, to 60 µg/day to achieve ≥30% reductions in iPTH. Calcium, phosphorus, 25D, 1,25-dihydroxyvitamin D (1,25D), iPTH, eGFR, fibroblast growth factor 23 (FGF23), bone turnover markers (BTM), and urine albumin-to-creatinine ratio (uACR) were measured at baseline (BL) and regular intervals. Participants were categorized by achievement (or not) of sustained ≥30% iPTH reductions over the last 2 quarters of treatment to evaluate differences in eGFR decline. RESULTS: For all participants, 25D increased 58.5±2.3 (SE) ng/mL (p<0.001) by the end of treatment (EOT), 1,25D increased 10.1±1.8 pg/mL (p<0.001), iPTH decreased from 143.8±5.8 pg/mL to 108.8±7.2 (p<0.001), BTMs improved (p<0.01) and eGFR declined 2.2±0.5 mL/min/1.73m2 (p<0.001). The rate of eGFR decline was >5-fold higher (p=0.014) in participants who did not achieve sustained iPTH reductions of ≥30% (3.2±0.7; 12.7±2.2%) than in those who did (0.6±0.8; 2.9±2.4%). It was highest in the 30 participants who did not exhibit an iPTH lowering response in both of the last 2 quarters of treatment (5.4±0.9; 20.9±3.4%). Duration of iPTH reduction had no impact on safety parameters. Degree of iPTH reduction at EOT was also associated with slower CKD progression. CONCLUSION: Sustained reduction of elevated iPTH with ERC treatment was associated with slower rates of eGFR decline in patients with SHPT and stage 3-4 CKD without raising safety concerns. A prospective trial is warranted to confirm this finding.

Smartphone-based hyperspectral imaging for ice sheet and proglacial applications in South-West Greenland.

Hyperspectral imaging is a valuable analytical technique with significant benefits for environmental monitoring. However, the application of these technologies remains limited, largely by the cost and bulk associated with available instrumentation. This results in a lack of high-resolution data from more challenging and extreme environmental settings, limiting our knowledge and understanding of the effects of climate change in these regions. In this article we challenge these limitations through the application of a low-cost, smartphone-based hyperspectral imaging instrument to measurement and monitoring activities at the Greenland Ice Sheet. Datasets are captured across a variety of supraglacial and proglacial locations covering visible and near infrared wavelengths. Our results are comparable to the existing literature, despite being captured with instrumentation costing over an order of magnitude less than currently available commercial technologies. Practicalities for field deployment are also explored, demonstrating our approach to be a valuable addition to the research field with the potential to improve the availability of datasets from across the cryosphere, unlocking a wealth of data collection opportunities that were hitherto infeasible.

Understanding and tuning the electronic structure of pentalenides.

Here we report the first example of systematic tuning of the electronic properties of dianionic pentalenides through a straightforward synthetic protocol which allows the controlled variation of substituents in the 1,3,4,6-positions to produce nine new compounds, representing the largest pentalenide study to date. Both electron-withdrawing as well as electron-donating aromatics have been incorporated to achieve different polarisations of the bicyclic 10π aromatic core as indicated by characteristic 1H and 13C NMR shifts and evaluated by DFT calculations including nucleus-independent chemical shift (NICS) scans, anisotropy of the induced current density (ACID) calculations, and natural bond orbital (NBO) charge distribution analysis. The introduction of methyl substituents to the pentalenide core required positional control in the dihydropentalene precursor to avoid exocyclic deprotonation during the metalation. Frontier orbital analyses showed arylated pentalenides to be slightly weaker donors but much better acceptor ligands than unsubstituted pentalenide. The coordination chemistry potential of our new ligands has been exemplified by the straightforward synthesis of a polarised anti-dirhodium(i) complex.

Evidence of aberrant anti-epstein-barr virus antibody response, though no viral reactivation, in people with post-stroke fatigue.

BACKGROUND: Fatigue is a common complication of stroke that has a significant impact on quality of life. The biological mechanisms that underly post-stroke fatigue are currently unclear, however, reactivation of latent viruses and their impact on systemic immune function have been increasingly reported in other conditions where fatigue is a predominant symptom. Epstein-Barr virus (EBV) in particular has been associated with fatigue, including in long-COVID and myalgic encephalomyelitis/chronic fatigue syndrome, but has not yet been explored within the context of stroke. AIMS: We performed an exploratory analysis to determine if there is evidence of a relationship between EBV reactivation and post-stroke fatigue. METHODS: In a chronic ischemic stroke cohort (> 5 months post-stroke), we assayed circulating EBV by qPCR and measured the titres of anti-EBV antibodies by ELISA in patients with high fatigue (FACIT-F < 40) and low fatigue (FACIT-F > 41). Statistical analysis between two-groups were performed by t-test when normally distributed according to the Shapiro-Wilk test, by Mann-Whitney test when the data was not normally distributed, and by Fisher's exact test for categorical data. RESULTS: We observed a similar incidence of viral reactivation between people with low versus high levels of post-stroke fatigue (5 of 22 participants (24%) versus 6 of 22 participants (27%)). Although the amount of circulating EBV was similar, we observed an altered circulating anti-EBV antibody profile in participants with high fatigue, with reduced IgM against the Viral Capsid Antigen (2.244 ± 0.926 vs. 3.334 ± 2.68; P = 0.031). Total IgM levels were not different between groups indicating this effect was specific to anti-EBV antibodies (3.23 × 105 ± 4.44 × 104 high fatigue versus 4.60 × 105 ± 9.28 × 104 low fatigue; P = 0.288). CONCLUSIONS: These data indicate that EBV is not more prone to reactivation during chronic stroke recovery in those with post-stroke fatigue. However, the dysregulated antibody response to EBV may be suggestive of viral reactivation at an earlier stage after stroke.

Self-Generated Lower Body Negative Pressure Exercise: A Low Power Countermeasure for Acute Space Missions.

Microgravity in spaceflight produces headward fluid shifts which probably contribute to Spaceflight-Associated Neuro-Ocular Syndrome (SANS). Developing new methods to mitigate these shifts is crucial for preventing SANS. One possible strategy is the use of self-generated lower body negative pressure (LBNP). This study evaluates biological or physiological effects induced by bed rest to simulate adaptations to microgravity. Participants were tested during powered LBNP and dynamic self-generated (SELF) LBNP at 25 mmHg for 15 min. The results were compared to the physiologic responses observed in seated upright and supine positions without LBNP, which served as controls for normal gravitational effects on fluid dynamics. Eleven participants' (five male, six female) heart rates, blood pressures, and cross-sectional areas (CSA) of left and right internal jugular veins (IJV) were monitored. Self-generated LBNP, which requires mild to moderate physical activity, significantly elevated heart rate and blood pressure (p < 0.01). Self-generated LBNP also significantly reduced right IJV CSA compared to supine position (p = 0.005), though changes on the left side were not significant (p = 0.365). While the effects of SELF and traditional LBNP on IJV CSA were largely similar, traditional LBNP significantly reduced IJV CSA on both sides. Given its low mass, volume, and power requirements, SELF LBNP is a promising countermeasure against SANS. Results from this study warrant longer-term studies of SELF LBNP under simulated spaceflight conditions.

Cell autonomous functions of CD47 in regulating cellular plasticity and metabolic plasticity.

CD47 is a ubiquitously expressed cell surface receptor, which is widely known for preventing macrophage-mediated phagocytosis by interacting with signal regulatory protein α (SIRPα) on the surface of macrophages. In addition to its role in phagocytosis, emerging studies have reported numerous noncanonical functions of CD47 that include regulation of various cellular processes such as proliferation, migration, apoptosis, differentiation, stress responses, and metabolism. Despite lacking an extensive cytoplasmic signaling domain, CD47 binds to several cytoplasmic proteins, particularly upon engaging with its secreted matricellular ligand, thrombospondin 1. Indeed, the regulatory functions of CD47 are greatly influenced by its interacting partners. These interactions are often cell- and context-specific, adding a further level of complexity. This review addresses the downstream cell-intrinsic signaling pathways regulated by CD47 in various cell types and environments. Some of the key pathways modulated by this receptor include the PI3K/AKT, MAPK/ERK, and nitric oxide signaling pathways, as well as those implicated in glucose, lipid, and mitochondrial metabolism. These pathways play vital roles in maintaining tissue homeostasis, highlighting the importance of understanding the phagocytosis-independent functions of CD47. Given that CD47 expression is dysregulated in a variety of cancers, improving our understanding of the cell-intrinsic signals regulated by this molecule will help advance the development of CD47-targeted therapies.

Computational modelling of cardiovascular pathophysiology to risk stratify commercial spaceflight.

For more than 60 years, humans have travelled into space. Until now, the majority of astronauts have been professional, government agency astronauts selected, in part, for their superlative physical fitness and the absence of disease. Commercial spaceflight is now becoming accessible to members of the public, many of whom would previously have been excluded owing to unsatisfactory fitness or the presence of cardiorespiratory diseases. While data exist on the effects of gravitational and acceleration (G) forces on human physiology, data on the effects of the aerospace environment in unselected members of the public, and particularly in those with clinically significant pathology, are limited. Although short in duration, these high acceleration forces can potentially either impair the experience or, more seriously, pose a risk to health in some individuals. Rather than expose individuals with existing pathology to G forces to collect data, computational modelling might be useful to predict the nature and severity of cardiovascular diseases that are of sufficient risk to restrict access, require modification, or suggest further investigation or training before flight. In this Review, we explore state-of-the-art, zero-dimensional, compartmentalized models of human cardiovascular pathophysiology that can be used to simulate the effects of acceleration forces, homeostatic regulation and ventilation-perfusion matching, using data generated by long-arm centrifuge facilities of the US National Aeronautics and Space Administration and the European Space Agency to risk stratify individuals and help to improve safety in commercial suborbital spaceflight.

Effectiveness of tenapanor for treating hyperphosphatemia in patients receiving dialysis: a plain language summary of the OPTIMIZE study.

What is this summary about?This summary provides a review of the OPTIMIZE study, the results of which were published in Kidney360 in February 2024. The OPTIMIZE study looked at how well tenapanor tablets work to treat patients receiving dialysis who have high levels of phosphate in their blood, a condition called hyperphosphatemia. In the OPTIMIZE study, researchers wanted to understand if tenapanor would decrease phosphate levels in the blood to the target range. They also tested different ways of starting tenapanor treatment in patients.In the human body, kidneys are organs that filter blood and remove waste products. In chronic kidney disease, sometimes referred to as CKD, a patient's kidneys do not work as well at filtering their blood and removing waste products. This can allow phosphate to build up in the blood. Phosphate levels may remain high despite patients receiving treatment such as dialysis, using pills that keep phosphate in the intestines (called phosphate binders) to prevent phosphate from being absorbed into the blood, and eating a low-phosphate diet. Phosphate levels may remain high despite these treatments because they can be difficult to follow. Most people receiving dialysis take 7­8 phosphate binder pills every day, and over half of those people have reported skipping at least one dose in the past month. Additionally, low-phosphate diets can be difficult to follow and people often struggle to meet their other nutritional needs.What are the key takeaways?Tenapanor used in combination with phosphate binders led to lower phosphate levels in the blood with the use of fewer phosphate-lowering pills. Tenapanor also lowered phosphate levels in patients who were not previously on phosphate binders but needed phosphate-lowering treatment.What were the main conclusions reported by the researchers?Tenapanor can help patients receiving dialysis better control their hyperphosphatemia.[Box: see text]Link to original article here.

Protection against experimental cryptococcosis elicited by Cationic Adjuvant Formulation 01-adjuvanted subunit vaccines.

The fungal infection, cryptococcosis, is responsible for >100,000 deaths annually. No licensed vaccines are available. We explored the efficacy and immune responses of subunit cryptococcal vaccines adjuvanted with Cationic Adjuvant Formulation 01 (CAF01). CAF01 promotes humoral and T helper (Th) 1 and Th17 immune responses and has been safely used in human vaccine trials. Four subcutaneous vaccines, each containing single recombinant Cryptococcus neoformans protein antigens, partially protected mice from experimental cryptococcosis. Protection increased, up to 100%, in mice that received bivalent and quadrivalent vaccine formulations. Vaccinated mice that received a pulmonary challenge with C. neoformans had an influx of leukocytes into the lung including robust numbers of polyfunctional CD4+ T cells which produced interferon gamma (IFNγ), tumor necrosis factor alpha (TNFα), and interleukin (IL)-17 upon ex vivo antigenic stimulation. Cytokine-producing lung CD8+ T cells were also found, albeit in lesser numbers. A significant, durable IFNγ response was observed in the lungs, spleen, and blood. Moreover, IFNγ secretion following ex vivo stimulation directly correlated with fungal control in the lungs. Thus, we have developed multivalent cryptococcal vaccines which protect mice from experimental cryptococcosis using an adjuvant which has been safely tested in humans. These preclinical studies suggest a path towards human cryptococcal vaccine trials.

Perihaematomal Oedema Evolution over 2 Weeks after Spontaneous Intracerebral Haemorrhage and Association with Outcome: A Prospective Cohort Study.

INTRODUCTION: We know little about the evolution of perihaematomal oedema (PHO) >24 h after ICH onset. We aimed to determine the trajectory of PHO after ICH onset and its association with outcome. METHODS: We did a prospective cohort study using a pre-specified scanning protocol in adults with first-ever spontaneous ICH and measured absolute PHO volumes on CT head scans at ICH diagnosis and 3 ± 2, 7 ± 2, and 14 ± 2 days after ICH onset. We used the largest ICH if ICHs were multiple. The primary outcomes were (a) the trajectory of PHO after ICH onset and (b) the association between PHO (absolute volume at the time when most repeat CT head scans were obtained, and change in PHO volume at this time compared with the first CT head scan) and poor functional outcome (modified Rankin scale 3-6 at 90 days). We pre-specified multivariable logistic regression models of this association adjusting analyses for potential confounders: age, GCS, infratentorial ICH location, and intraventricular extension. RESULTS: In 106 participants of whom 49 (46%) were female, with a median ICH volume 7 mL (interquartile range [IQR] 2-22 mL), the trajectory of median PHO volume increased from 14 mL (IQR: 7-26 mL) at diagnosis to 18 mL (IQR: 8-40 mL) at 3 ± 2 days (n = 87), 20 mL (IQR: 8-48 mL) at 7 ± 2 days (n = 93) and 21 mL (IQR: 10-54 mL) at 14 ± 2 days (n = 78) (p = <0.001). PHO volume at each time point was collinear with ICH volume at diagnosis (│r│ >0.7), but the change in PHO volume between diagnosis and each time point was not. Given collinearity, we used total lesion (i.e., ICH + PHO) volume instead of PHO volume in a logistic regression model of its association at each time point with outcome. Increasing total lesion (ICH + PHO) volume at day 7 ± 2 was associated with poor functional outcome (adjusted OR per mL 1.02, 95% CI: 1.00-1.03; p = 0.036), but the increase in PHO volume between diagnosis and day 7 ± 2 was not associated with poor functional outcome (adjusted OR per mL 1.03, 95% CI: 0.99-1.07; p = 0.132). CONCLUSION: PHO volume increases throughout the first 2 weeks after onset of mild to moderate ICH. Total lesion (ICH + PHO) volume at day 7 ± 2 was associated with poor functional outcome, but the change in PHO volume between diagnosis and day 7 ± 2 was not. Prospective cohort studies with larger sample sizes are needed to investigate these associations and their modifiers.

Immunological correlates of protection mediated by a whole organism, Cryptococcus neoformans, vaccine deficient in chitosan.

The global burden of infections due to the pathogenic fungus Cryptococcus is substantial in persons with low CD4+ T-cell counts. Previously, we deleted three chitin deacetylase genes from Cryptococcus neoformans to create a chitosan-deficient, avirulent strain, designated as cda1∆2∆3∆, which, when used as a vaccine, protected mice from challenge with virulent C. neoformans strain KN99. Here, we explored the immunological basis for protection. Vaccine-mediated protection was maintained in mice lacking B cells or CD8+ T cells. In contrast, protection was lost in mice lacking α/ß T cells or CD4+ T cells. Moreover, CD4+ T cells from vaccinated mice conferred protection upon adoptive transfer to naive mice. Importantly, while monoclonal antibody-mediated depletion of CD4+ T cells just prior to vaccination resulted in complete loss of protection, significant protection was retained in mice depleted of CD4+ T cells after vaccination but prior to challenge. Vaccine-mediated protection was lost in mice genetically deficient in interferon-γ (IFNγ), tumor necrosis factor alpha (TNFα), or interleukin (IL)-23p19. A robust influx of leukocytes and IFNγ- and TNFα-expressing CD4+ T cells was seen in the lungs of vaccinated and challenged mice. Finally, a higher level of IFNγ production by lung cells stimulated ex vivo correlated with lower fungal burden in the lungs. Thus, while B cells and CD8+ T cells are dispensable, IFNγ and CD4+ T cells have overlapping roles in generating protective immunity prior to cda1∆2∆3∆ vaccination. However, once vaccinated, protection becomes less dependent on CD4+ T cells, suggesting a strategy for vaccinating HIV+ persons prior to loss of CD4+ T cells. IMPORTANCE: The fungus Cryptococcus neoformans is responsible for >100,000 deaths annually, mostly in persons with impaired CD4+ T-cell function such as AIDS. There are no approved human vaccines. We previously created a genetically engineered avirulent strain of C. neoformans, designated as cda1∆2∆3∆. When used as a vaccine, cda1∆2∆3∆ protects mice against a subsequent challenge with a virulent C. neoformans strain. Here, we defined components of the immune system responsible for vaccine-mediated protection. We found that while B cells and CD8+ T cells were dispensible, protection was lost in mice genetically deficient in CD4+ T cells and the cytokines IFNγ, TNFα, or IL-23. A robust influx of cytokine-producing CD4+ T cells was seen in the lungs of vaccinated mice following infection. Importantly, protection was retained in mice depleted of CD4+ T cells following vaccination, suggesting a strategy to protect persons who are at risk of future CD4+ T-cell dysfunction.

The utility-and limitations-of the rodent synergist ablation model in examining mechanisms of skeletal muscle hypertrophy.

In this issue, Burke et al. discuss the utility of the rodent synergist ablation (SA) model for examining mechanisms associated with skeletal muscle hypertrophy. In this invited perspective, we aim to complement their original perspective by discussing limitations to the model along with alternative mechanical overload models that have strengths and limitations.