Combinatorial Single-Cell Analyses of Granulocyte-Monocyte Progenitor Heterogeneity Reveals an Early Uni-potent Neutrophil Progenitor.

Granulocyte-monocyte progenitors (GMPs) have been previously defined for their potential to generate various myeloid progenies such as neutrophils and monocytes. Although studies have proposed lineage heterogeneity within GMPs, it is unclear if committed progenitors already exist among these progenitors and how they may behave differently during inflammation. By combining single-cell transcriptomic and proteomic analyses, we identified the early committed progenitor within the GMPs responsible for the strict production of neutrophils, which we designate as proNeu1. Our dissection of the GMP hierarchy led us to further identify a previously unknown intermediate proNeu2 population. Similar populations could be detected in human samples. proNeu1s, but not proNeu2s, selectively expanded during the early phase of sepsis at the expense of monocytes. Collectively, our findings help shape the neutrophil maturation trajectory roadmap and challenge the current definition of GMPs.

Dengue virus infection modifies mosquito blood-feeding behavior to increase transmission to the host.

Mosquito blood-feeding behavior is a key determinant of the epidemiology of dengue viruses (DENV), the most-prevalent mosquito-borne viruses. However, despite its importance, how DENV infection influences mosquito blood-feeding and, consequently, transmission remains unclear. Here, we developed a high-resolution, video-based assay to observe the blood-feeding behavior of Aedes aegypti mosquitoes on mice. We then applied multivariate analysis on the high-throughput, unbiased data generated from the assay to ordinate behavioral parameters into complex behaviors. We showed that DENV infection increases mosquito attraction to the host and hinders its biting efficiency, the latter resulting in the infected mosquitoes biting more to reach similar blood repletion as uninfected mosquitoes. To examine how increased biting influences DENV transmission to the host, we established an in vivo transmission model with immuno-competent mice and demonstrated that successive short probes result in multiple transmissions. Finally, to determine how DENV-induced alterations of host-seeking and biting behaviors influence dengue epidemiology, we integrated the behavioral data within a mathematical model. We calculated that the number of infected hosts per infected mosquito, as determined by the reproduction rate, tripled when mosquito behavior was influenced by DENV infection. Taken together, this multidisciplinary study details how DENV infection modulates mosquito blood-feeding behavior to increase vector capacity, proportionally aggravating DENV epidemiology. By elucidating the contribution of mosquito behavioral alterations on DENV transmission to the host, these results will inform epidemiological modeling to tailor improved interventions against dengue.

Reducing the time to activation of the emergency call system in operating theatres: effect of installing vertical red line indicators.

BACKGROUND: The 7th National Audit Project of the Royal College of Anaesthetists (NAP7) recommended that an emergency call system be immediately accessible in all anaesthesia locations. It is essential that all theatre team members can rapidly call for help to reduce the risk of patient harm. However, the ability of staff to activate this system in a timely manner can be affected by cluttered or unfamiliar environments and cognitive overload. One proposed strategy to enable rapid identification and activation of emergency call systems is to install a red vertical painted stripe on the wall from the ceiling to the activation button. We investigated the effect of introducing this vertical red line on activation times in operating theatres in the UK and Australia. METHODS: Operating theatre team members, including anaesthetists, surgeons, anaesthetic nurses, surgical and theatre nurses, operating theatre practitioners, and technicians, were approached without prior warning and asked to simulate activation of an emergency call. Vertical red lines were installed, and data collection repeated in the same operating theatres 4-12 months later. RESULTS: After installation of vertical red lines, the proportion of activations taking >10 s decreased from 31.9% (30/94) to 13.6% (17/125, P=0.001), and >20 s decreased from 19.1% (18/94) to 4.8% (6/125, P<0.001). The longest duration pre-installation was 120 s, and post-installation 35 s. CONCLUSIONS: This simple, safe, and inexpensive design intervention should be considered as a design standard in all operating theatres to minimise delays in calling for help.

S1P-Dependent trafficking of intracellular yersinia pestis through lymph nodes establishes Buboes and systemic infection.

Pathologically swollen lymph nodes (LNs), or buboes, characterize Yersinia pestis infection, yet how they form and function is unknown. We report that colonization of the draining LN (dLN) occurred due to trafficking of infected dendritic cells and monocytes in temporally distinct waves in response to redundant chemotactic signals, including through CCR7, CCR2, and sphingosine-1-phospate (S1P) receptors. Retention of multiple subsets of phagocytes within peripheral LNs using the S1P receptor agonist FTY720 or S1P1-specific agonist SEW2871 increased survival, reduced colonization of downstream LNs, and limited progression to transmission-associated septicemic or pneumonic disease states. Conditional deletion of S1P1 in mononuclear phagocytes abolished node-to-node trafficking of infected cells. Thus, Y. pestis-orchestrated LN remodeling promoted its dissemination via host cells through the lymphatic system but can be blocked by prevention of leukocyte egress from DLNs. These findings define a novel trafficking route of mononuclear phagocytes and identify S1P as a therapeutic target during infection.

Mast cell interleukin-10 drives localized tolerance in chronic bladder infection.

The lower urinary tract's virtually inevitable exposure to external microbial pathogens warrants efficient tissue-specialized defenses to maintain sterility. The observation that the bladder can become chronically infected in combination with clinical observations that antibody responses after bladder infections are not detectable suggest defects in the formation of adaptive immunity and immunological memory. We have identified a broadly immunosuppressive transcriptional program specific to the bladder, but not the kidney, during infection of the urinary tract that is dependent on tissue-resident mast cells (MCs). This involves localized production of interleukin-10 and results in suppressed humoral and cell-mediated responses and bacterial persistence. Therefore, in addition to the previously described role of MCs orchestrating the early innate immunity during bladder infection, they subsequently play a tissue-specific immunosuppressive role. These findings may explain the prevalent recurrence of bladder infections and suggest the bladder as a site exhibiting an intrinsic degree of MC-maintained immune privilege.

Early Insights into Immune Responses during COVID-19.

Coronavirus disease-2019 (COVID-19) is caused by the newly emerged virus severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and was recently declared as a pandemic by the World Health Organization. In its severe form, the disease is characterized by acute respiratory distress syndrome, and there are no targeted intervention strategies to treat or prevent it. The immune response is thought to both contribute to the pathogenesis of disease and provide protection during its resolution. Thus, understanding the immune response to SARS-CoV-2 is of the utmost importance for developing and testing vaccines and therapeutics. In this review, we discuss the earliest knowledge and hypotheses of the mechanisms of immune pathology in the lung during acute infection as well at the later stages of disease resolution, recovery, and immune memory formation.

Infants' neural sensitivity to social interactions varies by income and infant-directed speech.

Social interactions are essential for infant brain development, yet we know little about how infant functional connectivity differs between social and nonsocial contexts, or how sensitivity to differences between contexts might be related to early distal and proximal environmental factors. We compared 12-month-old infants' intrahemispheric electroencephalographic (EEG) coherence between a social and a nonsocial condition, then examined whether differences between conditions varied as a function of family economic strain and two maternal behaviors at 6 months, positive affect and infant-directed speech. We found lower EEG coherence from the frontal region to the central, parietal, temporal, and occipital regions during the social condition, but only for infants from higher-income families and infants whose mothers used higher proportions of infant-directed speech. In contrast, there were no differences between social and nonsocial conditions for infants from economically strained families or infants whose mothers used lower proportions of infant-directed speech. This study demonstrates that neural organization differs between a nonsocial baseline and a social interaction, but said differentiation is not present for infants from less privileged backgrounds. Our results underscore the importance of examining brain activity during species-typical contexts to understand the role of environmental factors in brain development.

Infant diurnal cortisol predicts sleep.

The sleep-wake system is immature at birth and develops in parallel with the hypothalamic-pituitary-adrenal axis, a biological stress system of which the end product is cortisol. Perturbations in one system during infancy can maladaptively influence the maturation of the other system, leading to lasting sleep and cortisol system dysregulation and heightening the risk of enduring health problems. To better understand the early interplay between these systems, we examined whether actigraphy-derived measures of night-time sleep duration and onset were associated with cumulative exposure to cortisol, indexed by hair cortisol concentration, in 12-month-old children. Overall, early sleep onset predicted lower hair cortisol above and beyond sleep duration, family income and chaos experienced at home. Furthermore, both sleep and cortisol levels vary day to day, and temporal dependencies between daily sleep and cortisol regulation are not well understood. Thus, we assessed how the sleep characteristics on a particular evening related to salivary cortisol levels the following day and how daytime and evening cortisol related to the sleep characteristics on the same night. Lower total exposure to cortisol on a particular day was related to longer night-time sleep duration the same night, but not sleep onset. Lower salivary cortisol levels on a given evening related to earlier sleep onset the same night, but not to night-time sleep duration. Sleep duration and onset on a given night were unrelated to total cortisol exposure the following day. Findings suggest that in early development, the day-to-day relation between sleep and cortisol is not bidirectional, but more driven by diurnal cortisol.

A systematic assessment of socioeconomic status and executive functioning in early childhood.

Lower socioeconomic status (SES) consistently relates to poorer executive function (EF). This study used a systematic and nuanced approach to understand how SES relates to children's EF at a process level. We assessed children aged 4.5-5.5 years. This is a key developmental period because EF is no longer a unitary construct but rather EF components statistically load on separate factors and index distinct aspects of EF. Children completed a working memory task that involved a cognitive load component and a go/no-go task to assess inhibitory control and vigilance. Accuracy and reaction time were assessed, and each task involved four blocks to assess performance over time. Lower SES related to lower accuracy for working memory, inhibitory control, and vigilance as well as slower reaction time for working memory. SES did not relate to go/no-go reaction time. For working memory, lower SES related to poorer accuracy on lower cognitive load trials, but there were no SES differences on higher cognitive load trials. SES did not relate to maintenance of performance over time. Results suggest that for this age group the majority of domains showed SES differences. However, there were no SES differences in performance for remembering two items and maintaining performance. Thus, although overall lower SES related to poorer EF performance, there were no SES effects for skills that are still emerging for all children, namely, maintaining task performance across time and remembering two items at once. Results highlight the importance of assessing EF as a multidimensional construct and may help to identify targets for intervention.

20% Human Albumin Solution Fluid Bolus Administration Therapy in Patients After Cardiac Surgery (the HAS FLAIR Study).

OBJECTIVE: To compare the effects of fluid bolus therapy using 20% albumin versus crystalloid on fluid balance, hemodynamic parameters, and intensive care unit (ICU) treatment effects in post-cardiac surgery patients. DESIGN: Sequential period open-label pilot study. SETTING: University teaching hospital. PARTICIPANTS: One hundred adult cardiac surgery patients who were prescribed fluid bolus therapy to correct hypotension or perceived hypovolemia or to optimize cardiac index during the first 24 hours in the ICU. INTERVENTIONS: The first 50 patients were treated with crystalloid fluid bolus therapy in the first period (control), and 50 patients with up to 2 treatments of 100 mL of 20% albumin fluid bolus therapy in the second period (intervention), followed by crystalloid therapy if needed. MEASUREMENTS AND MAIN RESULTS: Demographic characteristics were similar at baseline. The intervention was associated with a less positive median fluid balance in the first 24 hours (albumin: 1,100 [650-1,960] v crystalloid: 1,970 [1,430-2,550] p = 0.001), fewer episodes of fluid bolus therapy (3 [2-5] v 5 [4-7]; p < 0.0001) and a lesser volume of fluid bolus therapy (700 [200-1,450] v 1,500 mL/24 h [1,100-2,250]; p < 0.0001). The intervention also was associated with a decreased median overall dose of norepinephrine in the first 24 hours of ICU stay (19 [0-52] v 47 µg/kg/24 hours [0-134]; p = 0.025) and shorter median time to cessation of norepinephrine (17 [5-28] v 28 hours [20-48]; p = 0.002). CONCLUSION: Post-cardiac surgery fluid bolus therapy with 20% albumin when compared with crystalloid fluid resulted in less positive fluid balance as well as several hemodynamic and potential ICU treatment advantages.

Transcriptional Profiling Confirms the Therapeutic Effects of Mast Cell Stabilization in a Dengue Disease Model.

There are no approved therapeutics for the treatment of dengue disease despite the global prevalence of dengue virus (DENV) and its mosquito vectors. DENV infections can lead to vascular complications, hemorrhage, and shock due to the ability of DENV to infect a variety of immune and nonimmune cell populations. Increasingly, studies have implicated the host response as a major contributor to severe disease. Inflammatory products of various cell types, including responding T cells, mast cells (MCs), and infected monocytes, can contribute to immune pathology. In this study, we show that the host response to DENV infection in immunocompetent mice recapitulates transcriptional changes that have been described in human studies. We found that DENV infection strongly induced metabolic dysregulation, complement signaling, and inflammation. DENV also affected the immune cell content of the spleen and liver, enhancing NK, NKT, and CD8+ T cell activation. The MC-stabilizing drug ketotifen reversed many of these responses without suppressing memory T cell formation and induced additional changes in the transcriptome and immune cell composition of the spleen, consistent with reduced inflammation. This study provides a global transcriptional map of immune activation in DENV target organs of an immunocompetent host and supports the further development of targeted immunomodulatory strategies to treat DENV disease.IMPORTANCE Dengue virus (DENV), which causes febrile illness, is transmitted by mosquito vectors throughout tropical and subtropical regions of the world. Symptoms of DENV infection involve damage to blood vessels and, in rare cases, hemorrhage and shock. Currently, there are no targeted therapies to treat DENV infection, but it is thought that drugs that target the host immune response may be effective in limiting symptoms that result from excessive inflammation. In this study, we measured the host transcriptional response to infection in multiple DENV target organs using a mouse model of disease. We found that DENV infection induced metabolic dysregulation and inflammatory responses and affected the immune cell content of the spleen and liver. The use of the mast cell stabilization drug ketotifen reversed many of these responses and induced additional changes in the transcriptome and immune cell repertoire that contribute to decreased dengue disease.

Salivary cortisol reactivity in preschoolers is associated with hair cortisol and behavioral problems.

The interplay between children's cortisol reactivity to challenge and cumulative cortisol exposure is not well understood. Examining the role of cortisol reactivity in early childhood may elucidate biological mechanisms that contribute to children's chronic physiological stress and behavioral dysregulation. In a sample of 65 preschool-aged children, we examined the relation between children's salivary cortisol reactivity to challenging tasks and their hair cortisol concentration (HCC). While both are biomarkers of the hypothalamic-pituitary-adrenal (HPA) axis, salivary cortisol reactivity reflects an acute cortisol response to a stressor and HCC reflects cumulative cortisol exposure. In addition, we examined the relations of these stress biomarkers with internalizing and externalizing problems. Salivary cortisol reactivity was associated with higher HCC and with increased externalizing behaviors. Child HCC also was positively correlated with parent HCC. Results highlight the contributions of salivary cortisol reactivity to children's cumulative cortisol exposure, which may add to their biological risk for health problems later. The observed association between externalizing problems and salivary cortisol reactivity indicates concordances between dysregulated behavioral reactions and dysregulated cortisol responses to challenges. The finding that salivary cortisol reactivity to challenge in early childhood plays a role in children's cumulative cortisol exposure and behavioral development suggests pathways through which cortisol reactivity may influence long-term physical and mental health.

Chymase Level Is a Predictive Biomarker of Dengue Hemorrhagic Fever in Pediatric and Adult Patients.

Background: Most patients with dengue experience mild disease, dengue fever (DF), while few develop the life-threatening diseases dengue hemorrhagic fever (DHF) or dengue shock syndrome (DSS). No laboratory tests predict DHF or DSS. We evaluated whether the serum chymase level can predict DHF or DSS in adult and pediatric patients and the influence of preexisting conditions (PECs) on chymase levels. Methods: Serum chymase levels were measured in patients presenting with undifferentiated fever to hospitals in Colombo District, Sri Lanka. The value of serum the chymase concentration and clinical signs and symptoms as predictors of DHF and/or DSS was evaluated by multivariate analysis. We assessed the influence of age, PECs, and day after fever onset on the robustness of the chymase level as a biomarker for DHF and/or DSS. Results: An elevated chymase level in acute phase blood samples was highly indicative of later diagnosis of DHF or DSS for pediatric and adult patients with dengue. No recorded PECs prevented an increase in the chymase level during DHF. However, certain PECs (obesity and cardiac or lung-associated diseases) resulted in a concomitant increase in chymase levels among adult patients with DHF. Conclusions: These results show that patients with acute dengue who present with high levels of serum chymase consistently are at greater risk of DHF. The chymase level is a robust prognostic biomarker of severe dengue for adult and pediatric patients.

Maternal cortisol slope at 6 months predicts infant cortisol slope and EEG power at 12 months.

Physiological stress systems and the brain rapidly develop through infancy. While the roles of caregiving and environmental factors have been studied, implications of maternal physiological stress are unclear. We assessed maternal and infant diurnal cortisol when infants were 6 and 12 months. We measured 12-month infant electroencephalography (EEG) 6-9 Hz power during a social interaction. Steeper 6-month maternal slope predicted steeper 12-month infant slope controlling for 6-month infant slope and breastfeeding. Steeper 6-month maternal slope predicted lower 6-9 Hz power. Six-month maternal area under the cuve (AUCg) was unrelated to 12-month infant AUCg and 6-9 Hz power. Psychosocial, caregiving, and breastfeeding variables did not explain results. At 6 months, maternal and infant slopes correlated, as did maternal and infant AUCg. Twelve-month maternal and infant cortisol were unrelated. Results indicate maternal slope is an informative predictor of infant physiology and suggest the importance of maternal physiological stress in this developmental period.

Infant hair cortisol: associations with salivary cortisol and environmental context.

Early chronic stress has enduring implications for physical and mental health outcomes. Hair cortisol concentration (HCC) has emerged as a marker of cumulative cortisol exposure, yet HCC in infants is not well understood. We examined how infant HCC relates to widely used basal salivary cortisol measures, maternal HCC, and environmental context in 111 infants assessed at 6 and 12 months of age. Maternal HCC at 6 and 12 months was correlated with infant HCC at 12 months. At 12 months, infant HCC was positively associated with waking salivary cortisol concentration (SCC), evening SCC, and area under the curve (AUC), but was independent of diurnal slope. Breastfeeding was associated with lower HCC, whereas increased sleep disruption was related to flatter slope. Reduced nighttime sleep duration was related both to higher HCC and to flatter slope. A person-focused analysis indicated that the combination of high HCC and flattened slope was associated with more environmental risks, highlighting the importance of investigating the interplay between HCC and diurnal cortisol slope. Results support the validity of HCC as a marker of cumulative cortisol exposure in infancy, while emphasizing the value of including multiple cortisol measures assessing distinct aspects of hypothalamic-pituitary-adrenal (HPA) function.

Variation in infant EEG power across social and nonsocial contexts.

To understand the infant social brain, it is critical to observe functional neural activation during social interaction. Yet many infant electroencephalography (EEG) studies on socioemotional development have recorded neural activity only during a baseline state. This study investigated how infant EEG power (4-6Hz and 6-9Hz) varies across social and nonsocial contexts. EEG was recorded in 12-month-olds across controlled conditions to disentangle the neural bases of social interactions. Four conditions-nonsocial, joint attention, language-only, and social engagement-were designed to tease apart how different environmental inputs relate to infant EEG power. We analyzed EEG power in frontal, central, temporal, and parietal regions. During the joint attention condition compared with the other conditions, 4-6Hz frontal, central, and parietal power was lowest, indexing greater neural activation. There was lower 4-6Hz and 6-9Hz power in the temporal region in both the joint attention and social engagement conditions compared with the nonsocial condition. In 6-9Hz, the pattern was consistent with 4-6Hz findings for the frontal region such that 6-9Hz frontal power was lower, indexing greater neural activation, in the joint attention condition compared with the nonsocial condition. There were no differences between conditions in central and parietal regions in 6-9Hz. Findings highlight the methodological importance of recording functional brain activity in multiple controlled contexts to explicate the neural bases of the infant social brain.

Innate immunity and its regulation by mast cells.

Mast cells (MCs), which are granulated tissue-resident cells of hematopoietic lineage, constitute a major sensory arm of the innate immune system. In this review we discuss the evidence supporting the dual role of MCs, both as sentinels for invading pathogens and as regulatory cells throughout the course of acute inflammation, from its initiation to resolution. This versatility is dependent on the ability of MCs to detect pathogens and danger signals and release a unique panel of mediators to promote pathogen-specific clearance mechanisms, such as through cellular recruitment or vascular permeability. It is increasingly understood that MCs also contribute to the regulated contraction of immune activation that occurs within tissues as inflammation resolves. This overarching regulatory control over innate immune processes has made MCs successful targets to purposefully enhance or, alternatively, suppress MC responses in multiple therapeutic contexts.

Immune surveillance by mast cells during dengue infection promotes natural killer (NK) and NKT-cell recruitment and viral clearance.

A wealth of evidence supports the essential contributions of mast cells (MCs) to immune defense against bacteria and parasites; however, the role of MCs in viral infections has not been defined. We now report that rodent, monkey, and human MCs are able to detect dengue virus (DENV), a lymphotropic, enveloped, single-stranded, positive-sense RNA virus that results in MC activation and degranulation. We observe that the response of MCs to DENV also involves the activation of antiviral intracellular host response pathways, melanoma differentiation-associated gene 5 (MDA5) and retinoic acid inducible gene 1 (RIG-I), and the de novo transcription of cytokines, including TNF-α and IFN-α, and chemokines, such as CCL5, CXCL12, and CX3CL1. This multifaceted response of MCs to DENV is consequential to the containment of DENV in vivo because, after s.c. infection, MC-deficient mice show increased viral burden within draining lymph nodes, which are known to be targeted organs during DENV spread, compared with MC-sufficient mice. This containment of DENV is linked to the MC-driven recruitment of natural killer and natural killer T cells into the infected skin. These findings support expanding the defined role of immunosurveillance by MCs to include viral pathogens.