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Abstract Following Mycobacterium tuberculosis infection, alveolar macrophages are initially infected but ineffectively restrict bacterial replication. The distribution of M. tuberculosis among different cell types in the lung changes with the onset of T cell immunity when the dominant infected cellular niche shifts from alveolar to monocyte-derived macrophages (MDM). We hypothesize that changes in bacterial distribution among different cell types is driven by differences in T cell recognition of infected cells and their subsequent activation of antimicrobial effector mechanisms. We show that CD4 and CD8 T cells efficiently eliminate M. tuberculosis infection in alveolar macrophages, but they have less impact on suppressing infection in MDM, which may be a bacterial niche. Importantly, CD4 T cell responses enhance MDM recruitment to the lung. Thus, the outcome of infection depends on the interaction between the T cell subset and the infected cell; both contribute to the resolution and persistence of the infection.

Summary: West and South Asian populations profoundly influenced Eurasian genetic and cultural diversity. We investigate the genetic history of the Y chromosome haplogroup L1-M22, which, while prevalent in these regions, lacks in-depth study. Robust Bayesian analyses of 165 high-coverage Y chromosomes favor a West Asian origin for L1-M22 ∼20.6 thousand years ago (kya). Moreover, this haplogroup parallels the genome-wide genetic ancestry of hunter-gatherers from the Iranian Plateau and the Caucasus. We characterized two L1-M22 harboring population groups during the Early Holocene. One expanded with the West Asian Neolithic transition. The other moved to South Asia ∼8-6 kya but showed no expansion. This group likely participated in the spread of Dravidian languages. These South Asian L1-M22 lineages expanded ∼4-3 kya, coinciding with the Steppe ancestry introduction. Our findings advance the current understanding of Eurasian historical dynamics, emphasizing L1-M22’s West Asian origin, associated population movements, and possible linguistic impacts.

Abstract Breakthrough findings in the clinical and preclinical development of tuberculosis (TB) vaccines have galvanized the field and suggest, for the first time since the development of bacille Calmette-Guérin (BCG), that a novel and protective TB vaccine is on the horizon. Here we highlight the TB vaccines that are in the development pipeline and review the basis for optimism in both the clinical and preclinical space. We describe immune signatures that could act as immunological correlates of protection (CoP) to facilitate the development and comparison of vaccines. Finally, we discuss new animal models that are expected to more faithfully model the pathology and complex immune responses observed in human populations.

Abstract Since the introduction of transvenous cardiac pacing leads, pacemaker system design has remained similar for several decades. Progressive miniaturisation of electronic circuitry and batteries has enabled a smaller, single pacing unit comprising the intracardiac electrodes, generator and computer. This review explores the development of leadless pacing, the clinical trials comparing leadless to transvenous pacing in addition to the future developments of multi-chamber leadless pacing.

Abstract Background Cynomolgus macaque (Macaca fascicularis) is an attractive animal model for the study of human disease and is extensively used in biomedical research. Cynomolgus macaques share behavioral, physiological, and genomic traits with humans and recapitulate human disease manifestations not observed in other animal species. To improve the use of the cynomolgus macaque model to investigate immune responses, we defined and characterized the T cell receptor (TCR) repertoire. Result We identified and analyzed the alpha (TRA), beta (TRB), gamma (TRG), and delta (TRD) TCR loci of the cynomolgus macaque. The expressed repertoire was determined using 22 unique lung samples from Mycobacterium tuberculosis infected cynomolgus macaques by single cell RNA sequencing. Expressed TCR alpha (TRAV) and beta (TRBV) variable region genes were enriched and identified using gene specific primers, which allowed their functional status to be determined. Analysis of the primers used for cynomolgus macaque TCR variable region gene enrichment showed they could also be used to amplify rhesus macaque (M. mulatta) variable region genes. Conclusion The genomic organization of the cynomolgus macaque has great similarity with the rhesus macaque and they shared > 90% sequence similarity with the human TCR repertoire. The identification of the TCR repertoire facilitates analysis of T cell immunity in cynomolgus macaques.

Heterogeneity in human immune responses is difficult to model in standard laboratory mice. To understand how host variation affects Bacillus Calmette Guerin–induced (BCG-induced) immunity against Mycobacterium tuberculosis, we studied 24 unique collaborative cross (CC) mouse strains, which differ primarily in the genes and alleles they inherit from founder strains. The CC strains were vaccinated with or without BCG and challenged with aerosolized M. tuberculosis. Since BCG protects only half of the CC strains tested, we concluded that host genetics has a major influence on BCG-induced immunity against M. tuberculosis infection, making it an important barrier to vaccine-mediated protection. Importantly, BCG efficacy is dissociable from inherent susceptibility to tuberculosis (TB). T cell immunity was extensively characterized to identify components associated with protection that were stimulated by BCG and recalled after M. tuberculosis infection. Although considerable diversity is observed, BCG has little impact on the composition of T cells in the lung after infection. Instead, variability is largely shaped by host genetics. BCG-elicited protection against TB correlated with changes in immune function. Thus, CC mice can be used to define correlates of protection and to identify vaccine strategies that protect a larger fraction of genetically diverse individuals instead of optimizing protection for a single genotype.

Conduction system pacing (CSP) has emerged as a promising novel delivery method for Cardiac Resynchronisation Therapy (CRT), providing an alternative to conventional biventricular epicardial (BiV) pacing in indicated patients. Despite increasing popularity and widespread uptake, CSP has rarely been specifically examined in patients with atrial fibrillation (AF), a cohort which forms a significant proportion of the heart failure (HF) population. In this review, we first examine the mechanistic evidence for the importance of sinus rhythm (SR) in CSP by allowing adjustment of atrioventricular delays (AVD) to achieve the optimal electrical response, and thus, whether the efficacy of CSP may be significantly attenuated compared to conventional BiV pacing in the presence of AF. We next evaluate the largest clinical body of evidence in this field, related to patients receiving CSP following atrioventricular nodal ablation (AVNA) for AF. Finally, we discuss how future research may be designed to address the vital question of how effective CSP in AF patients is, and the potential hurdles we may face in delivering such studies.

Leadless pacing is a rapidly growing field. Initially designed to provide right ventricular pacing for those who were contraindicated for conventional devices, the technology is growing to explore the potential benefit of avoiding long-term transvenous leads in any patient who requires pacing. In this review, we first examine the safety and performance of leadless pacing devices. We then review the evidence for their use in special populations, such as patients with high risk of device infection, patients on haemodialysis, and patients with vasovagal syncope who represent a younger population who may wish to avoid transvenous pacing. We also summarise the evidence for leadless cardiac resynchronisation therapy and conduction system pacing and discuss the challenges of managing issues, such as system revisions, end of battery life and extractions. Finally, we discuss future directions in the field, such as completely leadless cardiac resynchronisation therapy-defibrillator devices and whether leadless pacing has the potential to become a first-line therapy in the near future.

Non-responders to Cardiac Resynchronization Therapy (CRT) represent a high-risk, and difficult to treat population of heart failure patients. Studies have shown that these patients have a lower quality of life and reduced life expectancy compared to those who respond to CRT. Whilst the first-line treatment for dyssynchronous heart failure is “conventional” biventricular epicardial CRT, a range of novel pacing interventions have emerged as potential alternatives. This has raised the question whether these new treatments may be useful as a second-line pacing intervention for treating non-responders, or indeed, whether some patients may benefit from these as a first-line option. In this review, we will examine the current evidence for four pacing interventions in the context of treatment of conventional CRT non-responders: CRT optimization; multisite left ventricular pacing; left ventricular endocardial pacing and conduction system pacing.

ABSTRACT The cytotoxic granules of human NK and CD8 T cells contain the effector molecule granulysin. Although in vitro studies indicate that granulysin is bactericidal to Mycobacterium tuberculosis and human CD8 T cells restrict intracellular M. tuberculosis by granule exocytosis, the role of granulysin in cell-mediated immunity against infection is incompletely understood, in part because a granulysin gene ortholog is absent in mice. Transgenic mice that express human granulysin (GNLY-Tg) under the control of human regulatory DNA sequences permit the study of granulysin in vivo. We assessed whether granulysin expression by murine CD8 T cells enhances their control of M. tuberculosis infection. GNLY-Tg mice did not control pulmonary M. tuberculosis infection better than non-Tg control mice, and purified GNLY-Tg and non-Tg CD8 T cells had a similar ability to transfer protection to T cell deficient mice. Lung CD8 T cells from infected control and GNLY-transgenic mice similarly controlled intracellular M. tuberculosis growth in macrophages in vitro. Importantly, after M. tuberculosis infection of GNLY-Tg mice, granulysin was detected in NK cells but not in CD8 T cells. Only after prolonged in vitro stimulation could granulysin expression be detected in antigen-specific CD8 T cells. GNLY-Tg mice are an imperfect model to determine whether granulysin expression by CD8 T cells enhances immunity against M. tuberculosis. Better models expressing granulysin are needed to explore the role of this antimicrobial effector molecule in vivo. IMPORTANCE Human CD8 T cells express the antimicrobial peptide granulysin in their cytotoxic granules, and in vitro analysis suggest that it restricts growth of Mycobacterium tuberculosis and other intracellular pathogens. The murine model of tuberculosis cannot assess granulysin’s role in vivo, as rodents lack the granulysin gene. A long-held hypothesis is that murine CD8 T cells inefficiently control M. tuberculosis infection because they lack granulysin. We used human granulysin transgenic (GNLY-Tg) mice to test this hypothesis. GNLY-Tg mice did not differ in their susceptibility to tuberculosis. However, granulysin expression by pulmonary CD8 T cells could not be detected after M. tuberculosis infection. As the pattern of granulysin expression in human CD8 T cells and GNLY-Tg mice seem to differ, GNLY-Tg mice are an imperfect model to study the role of granulysin. An improved model is needed to answer the importance of granulysin expression by CD8 T cells in different diseases.

Background: Isolated congenital complete heart block (CCHB) is rare cardiac condition associated with maternal Anti-Rho antibodies. It is managed with permanent pacemaker insertion. We sought to determine the long-term outcomes of individuals with CCHB who had undergone pacemaker insertion. Methods: A database search was performed at a UK tertiary cardiac referral centre. The online medical records of patients with CCHB were analysed for pacing requirements and complications, echocardiographic data, and clinical status. Results: A total of 72 patients (female n = 46) were identified, 20% of whom were autoantibody positive. Mean age of initial implantation was 15.5 years (SD 12.7) with mean follow up of 21 years (SD 8.3). 88% of patients were NYHA class I at censure of data. Major adverse cardiac events (MACE) were observed in 2 patients with 0% mortality throughout the follow up period. 16 patients (22.2%) developed cardiomyopathy, of which 15 had CRT devices inserted.Five patients had device related infections and 7 required system extractions. Mean left ventricular ejection fraction on most recent echocardiogram was 53.7% (SD 8.40) with no significant change compared with their historic scan. Mild tricuspid regurgitation was the most frequently observed valvular pathology, identified in 28% of patients. Only 2 patients (2.7%) had severe valve incompetence but neither required surgical intervention. Conclusion: Long-term outcomes for patients with congenital complete heart block who undergo pacemaker insertion are highly favourable. Despite high pacing requirements over an extended period, the incidence of MACE and pacing related complications is low. Cardiac function and valvular competence are largely preserved but dilated cardiomyopathy remains a late concern in a minority; ongoing clinical surveillance is paramount in this population.

Conduction System Pacing (CSP) delivered by His Bundle Pacing (HBP) or Left Bundle Pacing (LBP) are exciting novel interventions in the field of Cardiac Resynchronization Therapy (CRT). As the evidence base for CSP grows, the volume of implants worldwide is projected to rise significantly in the coming years. As such, physicians will be confronted with increasingly prevalent and vital issues arising in long-term follow up, including the management of infected, malfunctioning, or redundant CSP leads. Transvenous lead extraction (TLE) is the first-line option for removal of pacing leads when indicated in these circumstances. The evidence base for TLE in the context of CSP is still in its infancy. In this article, we first provide a brief overview of TLE. We then examine the data on the long-term performance of HBP leads. Next, we describe the features of the Medtronic Select Secure 3,830 lead, and how experience of TLE of this lead in the paediatric population has informed our practice. Finally, we review the current evidence for TLE in HBP and LBP, and discuss how future studies can address gaps in our current knowledge.

Abstract Human Y chromosome haplogroup J1-M267 is a common male lineage in West Asia. One high-frequency region—encompassing the Arabian Peninsula, southern Mesopotamia, and the southern Levant—resides ~ 2000 km away from the other one found in the Caucasus. The region between them, although has a lower frequency, nevertheless demonstrates high genetic diversity. Studies associate this haplogroup with the spread of farming from the Fertile Crescent to Europe, the spread of mobile pastoralism in the desert regions of the Arabian Peninsula, the history of the Jews, and the spread of Islam. Here, we study past human male demography in West Asia with 172 high-coverage whole Y chromosome sequences and 889 genotyped samples of haplogroup J1-M267. We show that this haplogroup evolved ~ 20,000 years ago somewhere in northwestern Iran, the Caucasus, the Armenian Highland, and northern Mesopotamia. The major branch—J1a1a1-P58—evolved during the early Holocene ~ 9500 years ago somewhere in the Arabian Peninsula, the Levant, and southern Mesopotamia. Haplogroup J1-M267 expanded during the Chalcolithic, the Bronze Age, and the Iron Age. Most probably, the spread of Afro-Asiatic languages, the spread of mobile pastoralism in the arid zones, or both of these events together explain the distribution of haplogroup J1-M267 we see today in the southern regions of West Asia.

Abstract Recent dose reduction techniques have made retrospective computed tomography (CT) scans more applicable and extracting myocardial function from cardiac computed tomography (CCT) images feasible. However, hyperparameters of generic image intensity-based registration techniques, which are used for tracking motion, have not been systematically optimised for this modality. There is limited work on their validation for measuring regional strains from retrospective gated CCT images and open-source software for motion analysis is not widely available. We calculated strain using our open-source platform by applying an image registration warping field to a triangulated mesh of the left ventricular endocardium. We optimised hyperparameters of two registration methods to track the wall motion. Both methods required a single semi-automated segmentation of the left ventricle cavity at end-diastolic phase. The motion was characterised by the circumferential and longitudinal strains, as well as local area change throughout the cardiac cycle from a dataset of 24 patients. The derived motion was validated against manually annotated anatomical landmarks and the calculation of strains were verified using idealised problems. Optimising hyperparameters of registration methods allowed tracking of anatomical measurements with a mean error of 6.63% across frames, landmarks, and patients, comparable to an intra-observer error of 7.98%. Both registration methods differentiated between normal and dyssynchronous contraction patterns based on circumferential strain ( $$p_1=0.0065$$ p 1 = 0.0065 , $$p_2=0.0011$$ p 2 = 0.0011 ). To test whether a typical 10 temporal frames sampling of retrospective gated CCT datasets affects measuring cardiac mechanics, we compared motion tracking results from 10 and 20 frames datasets and found a maximum error of $$8.51\pm 0.8\%$$ 8.51 ± 0.8 % . Our findings show that intensity-based registration techniques with optimal hyperparameters are able to accurately measure regional strains from CCT in a very short amount of time. Furthermore, sufficient sensitivity can be achieved to identify heart failure patients and left ventricle mechanics can be quantified with 10 reconstructed temporal frames. Our open-source platform will support increased use of CCT for quantifying cardiac mechanics.

ABSTRACT There is growing evidence that genetic diversity in Mycobacterium tuberculosis, the causative agent of tuberculosis, contributes to the outcomes of infection and public health interventions, such as vaccination. Epidemiological studies suggest that among the phylogeographic lineages of M. tuberculosis, strains belonging to a sublineage of Lineage 2 (mL2) are associated with concerning clinical features, including hypervirulence, treatment failure, and vaccine escape. The global expansion and increasing prevalence of this sublineage has been attributed to the selective advantage conferred by these characteristics, yet confounding host and environmental factors make it difficult to identify the bacterial determinants driving these associations in human studies. Here, we developed a molecular barcoding strategy to facilitate high-throughput, experimental phenotyping of M. tuberculosis clinical isolates. This approach allowed us to characterize growth dynamics for a panel of genetically diverse M. tuberculosis strains during infection and after vaccination in the mouse model. We found that mL2 strains exhibit distinct growth dynamics in vivo and are resistant to the immune protection conferred by Bacillus Calmette-Guerin (BCG) vaccination. The latter finding corroborates epidemiological observations and demonstrates that mycobacterial features contribute to vaccine efficacy. To investigate the genetic and biological basis of mL2 strains’ distinctive phenotypes, we performed variant analysis, transcriptional studies, and genome-wide transposon sequencing. We identified functional genetic changes across multiple stress and host response pathways in a representative mL2 strain that are associated with variants in regulatory genes. These adaptive changes may underlie the distinct clinical characteristics and epidemiological success of this lineage. IMPORTANCE Tuberculosis, caused by the bacterium Mycobacterium tuberculosis, is a remarkably heterogeneous disease, a feature that complicates clinical care and public health interventions. The contributions of pathogen genetic diversity to this heterogeneity are uncertain, in part due to the challenges of experimentally manipulating M. tuberculosis, a slow-growing, biosafety level 3 organism. To overcome these challenges, we applied a molecular barcoding strategy to a panel of M. tuberculosis clinical isolates. This novel application of barcoding permitted the high-throughput characterization of M. tuberculosis strain growth dynamics and vaccine resistance in the mouse model of infection. Integrating these results with genomic analyses, we uncover bacterial pathways that contribute to infection outcomes, suggesting targets for improved therapeutics and vaccines.

Leadless left bundle branch area pacing (LBBAP) represents the merger of two rapidly progressing areas in the field of cardiac resynchronisation therapy (CRT). It combines the attractive concepts of pacing the native conduction system to allow more physiological activation of the myocardium than conventional biventricular pacing, with the potential added benefits of avoiding long-term complications associated with transvenous leads via leadless left ventricular endocardial pacing. This perspective article will first review the evidence for the efficacy of leadless pacing in CRT. We then summarise the procedural steps and pilot data for leadless LBBAP, followed by a discussion of the safety and efficacy of this novel technique. Finally, we will examine how further mechanistic evidence may shed light to which patients may benefit most from leadless LBBAP, and how improvements in current experience and technology could promote widespread uptake and expand current clinical indications.

Disseminated infection with the high virulence strain of Mycobacterium avium 25291 leads to progressive thymic atrophy. We previously showed that M. avium-induced thymic atrophy results from increased glucocorticoid levels that synergize with nitric oxide (NO) produced by interferon gamma (IFNγ) activated macrophages. Where and how these mediators act is not understood. We hypothesized that IFNγ and NO promote thymic atrophy through their effects on bone marrow (BM) T cell precursors and T cell differentiation in the thymus. We show that M. avium infection cause a reduction in the percentage and number of common lymphoid progenitors (CLP). Additionally, BM precursors from infected mice show an overall impaired ability to reconstitute thymi of RAGKO mice, in part due to IFNγ. Thymi from infected mice present an IFNγ and NO-driven inflammation. When transplanted under the kidney capsule of uninfected mice, thymi from infected mice are unable to sustain T cell differentiation. Finally, we observed increased thymocyte death via apoptosis after infection, independent of both IFNγ and iNOS; and a decrease on active caspase-3 positive thymocytes, which is not observed in the absence of iNOS expression. Together our data suggests that M. avium-induced thymic atrophy results from a combination of defects mediated by IFNγ and NO, including alterations in the BM T cell precursors, the thymic structure and the thymocyte differentiation.

The immunological synapse allows antigen-presenting cells (APCs) to convey a wide array of functionally distinct signals to T cells, which ultimately shape the immune response. The relative effect of stimulatory and inhibitory signals is influenced by the activation state of the APC, which is determined by an interplay between signal transduction and metabolic pathways. While pathways downstream of toll-like receptors rely on glycolytic metabolism for the proper expression of inflammatory mediators, little is known about the metabolic dependencies of other critical signals such as interferon gamma (IFNγ). Using CRISPR-Cas9, we performed a series of genome-wide knockout screens in murine macrophages to identify the regulators of IFNγ-inducible T cell stimulatory or inhibitory proteins MHCII, CD40, and PD-L1. Our multiscreen approach enabled us to identify novel pathways that preferentially control functionally distinct proteins. Further integration of these screening data implicated complex I of the mitochondrial respiratory chain in the expression of all three markers, and by extension the IFNγ signaling pathway. We report that the IFNγ response requires mitochondrial respiration, and APCs are unable to activate T cells upon genetic or chemical inhibition of complex I. These findings suggest a dichotomous metabolic dependency between IFNγ and toll-like receptor signaling, implicating mitochondrial function as a fulcrum of innate immunity.

Summary: CD4 T cells are essential for immunity to tuberculosis because they produce cytokines, including interferon-γ. Whether CD4 T cells act as “helper” cells to promote optimal CD8 T cell responses during Mycobacterium tuberculosis is unknown. Using two independent models, we show that CD4 T cell help enhances CD8 effector functions and prevents CD8 T cell exhaustion. We demonstrate synergy between CD4 and CD8 T cells in promoting the survival of infected mice. Purified helped, but not helpless, CD8 T cells efficiently restrict intracellular bacterial growth in vitro. Thus, CD4 T cell help plays an essential role in generating protective CD8 T cell responses against M. tuberculosis infection in vitro and in vivo. We infer vaccines that elicit both CD4 and CD8 T cells are more likely to be successful than vaccines that elicit only CD4 or CD8 T cells.

CD8 T cells provide limited protection against Mycobacterium tuberculosis (Mtb) infection in the mouse model. As Mtb causes chronic infection in mice and humans, we hypothesize that Mtb impairs T cell responses as an immune evasion strategy. TB10.4 is an immunodominant antigen in people, nonhuman primates, and mice, which is encoded by the esxH gene. In C57BL/6 mice, 30-50% of pulmonary CD8 T cells recognize the TB10.44-11 epitope. However, TB10.4-specific CD8 T cells fail to recognize Mtb-infected macrophages. We speculate that Mtb elicits immunodominant CD8 T cell responses to antigens that are inefficiently presented by infected cells, thereby focusing CD8 T cells on nonprotective antigens. Here, we leverage naturally occurring polymorphisms in esxH, which frequently occur in lineage 1 strains, to test this "decoy hypothesis". Using the clinical isolate 667, which contains an EsxHA10T polymorphism, we observe a drastic change in the hierarchy of CD8 T cells. Using isogenic Erd.EsxHA10T and Erd.EsxHWT strains, we prove that this polymorphism alters the hierarchy of immunodominant CD8 T cell responses. Our data are best explained by immunodomination, a mechanism by which competition for APC leads to dominant responses suppressing subdominant responses. These results were surprising as the variant epitope can bind to H2-Kb and is recognized by TB10.4-specific CD8 T cells. The dramatic change in TB10.4-specific CD8 responses resulted from increased proteolytic degradation of A10T variant, which destroyed the TB10.44-11epitope. Importantly, this polymorphism affected T cell priming and recognition of infected cells. These data support a model in which nonprotective CD8 T cells become immunodominant and suppress subdominant responses. Thus, polymorphisms between clinical Mtb strains, and BCG or H37Rv sequence-based vaccines could lead to a mismatch between T cells that are primed by vaccines and the epitopes presented by infected cells. Reprograming host immune responses should be considered in the future design of vaccines.

During tuberculosis, lung myeloid cells have two opposing roles: they are an intracellular niche occupied by Mycobacterium tuberculosis, and they restrict bacterial replication. Lung myeloid cells from mice infected with yellow-fluorescent protein expressing M. tuberculosis were analyzed by flow cytometry and transcriptional profiling to identify the cell types infected and their response to infection. CD14, CD38, and Abca1 were expressed more highly by infected alveolar macrophages and CD11cHi monocyte-derived cells compared to uninfected cells. CD14, CD38, and Abca1 "triple positive" (TP) cells had not only the highest infection rates and bacterial loads, but also a strong interferon-γ signature and nitric oxide synthetase-2 production indicating recognition by T cells. Despite evidence of T cell recognition and appropriate activation, these TP macrophages are a cellular compartment occupied by M. tuberculosis long-term. Defining the niche where M. tuberculosis resists elimination promises to provide insight into why inducing sterilizing immunity is a formidable challenge.

Background: Biventricular pacing has been shown to increase both cardiac contractility and coronary flow acutely but the causal relationship is unclear. We hypothesised that changes in coronary flow are secondary to changes in cardiac contractility. We sought to examine this relationship by modulating coronary flow and cardiac contractility. Methods: Contractility and lusitropy were altered by varying the location of pacing in 8 patients. Coronary autoregulation was transiently disabled with intracoronary adenosine. Simultaneous coronary flow velocity, coronary pressure and left ventricular pressure data were measured in the different pacing settings with and without hyperaemia and wave intensity analysis performed. Results: Multisite pacing was effective at altering left ventricular contractility and lusitropy (pos. dp/dtmax −13% to +10% and neg. dp/dtmax −15% to +17% compared to baseline). Intracoronary adenosine decreased microvascular resistance (362.5 mm Hg/s/m to 156.7 mm Hg/s/m, p

Background: Trials using echocardiographic mechanical dyssynchrony (MD) parameters in narrow QRS patients have shown a negative response to CRT. We hypothesized MD in these patients may relate to myocardial scar rather than electrical dyssynchrony. Methods: We determined the prevalence of cardiac magnetic resonance (CMR) derived measures of MD in 130 systolic heart failure patients with both broad (≥130 ms - BQRS) and narrow QRS duration (

n-GaN/ AlN heterostructures were grown by molecular beam epitaxy on Si(111) substrates.The GaN films were n-type doped with silicon and the effect of doping concentration on the structural and optical properties was studied. Si doping promotes a reduction of dislocation density as revealed by x-ray data analysis and Transmission Electron Microscopy. Furthermore, a decrease in the yellow band measured by Photoluminescence Spectroscopy was observed when silicon doping concentration was increased up to 1.7 × 10 ^19 atoms cm ^−3 . A particular mosaic structure was induced by the Si-doping as inferred from Rutherford Backscattering measurements. The crystal quality shows a small degradation for very heavily doped samples (1.3 × 10 ^20 atoms cm ^−3 ).

Computational models of the heart are increasingly being used in the development of devices, patient diagnosis and therapy guidance. While software techniques have been developed for simulating single hearts, there remain significant challenges in simulating cohorts of virtual hearts from multiple patients. To facilitate the development of new simulation and model analysis techniques by groups without direct access to medical data, image analysis techniques and meshing tools, we have created the first publicly available virtual cohort of twenty-four four-chamber hearts. Our cohort was built from heart failure patients, age 67±14 years. We segmented four-chamber heart geometries from end-diastolic (ED) CT images and generated linear tetrahedral meshes with an average edge length of 1.1±0.2mm. Ventricular fibres were added in the ventricles with a rule-based method with an orientation of -60° and 80° at the epicardium and endocardium, respectively. We additionally refined the meshes to an average edge length of 0.39±0.10mm to show that all given meshes can be resampled to achieve an arbitrary desired resolution. We ran simulations for ventricular electrical activation and free mechanical contraction on all 1.1mm-resolution meshes to ensure that our meshes are suitable for electro-mechanical simulations. Simulations for electrical activation resulted in a total activation time of 149±16ms. Free mechanical contractions gave an average left ventricular (LV) and right ventricular (RV) ejection fraction (EF) of 35±1% and 30±2%, respectively, and a LV and RV stroke volume (SV) of 95±28mL and 65±11mL, respectively. By making the cohort publicly available, we hope to facilitate large cohort computational studies and to promote the development of cardiac computational electro-mechanics for clinical applications.

ABSTRACT Host genetics plays an important role in determining the outcome of Mycobacterium tuberculosis infection. We previously found that Collaborative Cross (CC) mouse strains differ in their susceptibility to M. tuberculosis and that the CC042/GeniUnc (CC042) strain suffered from a rapidly progressive disease and failed to produce the protective cytokine gamma interferon (IFN-γ) in the lung. Here, we used parallel genetic and immunological approaches to investigate the basis of CC042 mouse susceptibility. Using a population derived from a CC001/Unc (CC001) × CC042 intercross, we mapped four quantitative trait loci (QTL) underlying tuberculosis immunophenotypes (Tip1 to Tip4). These included QTL that were associated with bacterial burden, IFN-γ production following infection, and an IFN-γ-independent mechanism of bacterial control. Further immunological characterization revealed that CC042 animals recruited relatively few antigen-specific T cells to the lung and that these T cells failed to express the integrin alpha L (αL; i.e., CD11a), which contributes to T cell activation and migration. These defects could be explained by a CC042 private variant in the Itgal gene, which encodes CD11a and is found within the Tip2 interval. This 15-bp deletion leads to aberrant mRNA splicing and is predicted to result in a truncated protein product. The ItgalCC042 genotype was associated with all measured disease traits, indicating that this variant is a major determinant of susceptibility in CC042 mice. The combined effect of functionally distinct Tip variants likely explains the profound susceptibility of CC042 mice and highlights the multigenic nature of tuberculosis control in the Collaborative Cross. IMPORTANCE The variable outcome of Mycobacterium tuberculosis infection observed in natural populations is difficult to model in genetically homogeneous small-animal models. The newly developed Collaborative Cross (CC) represents a reproducible panel of genetically diverse mice that display a broad range of phenotypic responses to infection. We explored the genetic basis of this variation, focusing on a CC line that is highly susceptible to M. tuberculosis infection. This study identified multiple quantitative trait loci associated with bacterial control and cytokine production, including one that is caused by a novel loss-of-function mutation in the Itgal gene, which is necessary for T cell recruitment to the infected lung. These studies verify the multigenic control of mycobacterial disease in the CC panel, identify genetic loci controlling diverse aspects of pathogenesis, and highlight the utility of the CC resource.

Objectives: The gene encoding glucose transporter 3 (GLUT3, SLC2A3) is present in the human population at variable copy number. An overt disease phenotype of SLC2A3 copy number variants has not been reported; however, deletion of SLC2A3 has been previously reported to protect carriers from rheumatoid arthritis, implicating GLUT3 as a therapeutic target in rheumatoid arthritis. Here we aim to perform functional analysis of GLUT3 copy number variants in immune cells, and test the reported protective association of the GLUT3 copy number variants for rheumatoid arthritis in a genetic replication study. Methods: Cells from genotyped healthy controls were analyzed for SLC2A3/GLUT3 expression and glycolysis capacity. We genotyped the SLC2A3 copy number variant in four independent cohorts of rheumatoid arthritis and controls and one cohort of multiple sclerosis and controls. Results: Heterozygous deletion of SLC2A3 correlates directly with expression levels of GLUT3 and influences glycolysis rates in the human immune system. The frequency of the SLC2A3 copy number variant is not different between rheumatoid arthritis, multiple sclerosis and control groups. Conclusions: Despite a robust SLC2A3 gene copy number dependent phenotype, our study of large groups of rheumatoid arthritis cases and controls provides no evidence for rheumatoid arthritis disease protection in deletion carriers. These data emphasize the importance of well powered replication studies to confirm or refute genetic associations, particularly for relatively rare variants. Keywords: GLUT3, SLC2A3, Glycolysis, Deletion, Rheumatoid arthritis, Copy number variant, Glucose transport

Study hypothesis. We sought to investigate the association between echocardiographic optimisation and ventricular activation time in cardiac resynchronisation therapy (CRT) patients, obtained through the use of electrocardiographic mapping (ECM). We hypothesised that echocardiographic optimisation of the pacing delay between the atrial and ventricular leads—atrioventricular delay (AVD)—and the delay between ventricular leads—interventricular pacing interval (VVD)—would correlate with reductions in ventricular activation time. Background. Optimisation of AVD and VVD may improve CRT patient outcome. Optimal delays are currently set based on echocardiographic indices; however, acute studies have found that reductions in bulk ventricular activation time correlate with improvements in acute haemodynamic performance. Materials and methods. Twenty-one patients with established CRT criteria were recruited. After implantation, patients underwent echo-guided optimisation of the AVD and VVD. During this procedure, the participants also underwent noninvasive ECM. ECM maps were constructed for each AVD and VVD. ECM maps were analysed offline. Total ventricular activation time (TVaT) and a ventricular activation time index (VaT10-90) were calculated to identify the optimal AVD and VVD timings that gave the minimal TVaT and VaT10-90 values. We correlated cardiac output with these electrical timings. Results. Echocardiographic programming optimisation was not associated with the greatest reductions in biventricular activation time (VaT10-90 and TVaT). Instead, bulk activation times were reduced by a further 20% when optimised with ECM. A significant inverse correlation was identified between reductions in bulk ventricular activation time and improvements in LVOT VTI (p

Containment of Mycobacterium tuberculosis (Mtb) infection requires T cell recognition of infected macrophages. Mtb has evolved to tolerate, evade, and subvert host immunity. Despite a vigorous and sustained CD8+ T cell response during Mtb infection, CD8+ T cells make limited contribution to protection. Here, we ask whether the ability of Mtb-specific T cells to restrict Mtb growth is related to their capacity to recognize Mtb-infected macrophages. We derived CD8+ T cell lines that recognized the Mtb immunodominant epitope TB10.44-11 and compared them to CD4+ T cell lines that recognized Ag85b240-254 or ESAT63-17. While the CD4+ T cells recognized Mtb-infected macrophages and inhibited Mtb growth in vitro, the TB10.4-specific CD8+ T cells neither recognized Mtb-infected macrophages nor restricted Mtb growth. TB10.4-specific CD8+ T cells recognized macrophages infected with Listeria monocytogenes expressing TB10.4. However, over-expression of TB10.4 in Mtb did not confer recognition by TB10.4-specific CD8+ T cells. CD8+ T cells recognized macrophages pulsed with irradiated Mtb, indicating that macrophages can efficiently cross-present the TB10.4 protein and raising the possibility that viable bacilli might suppress cross-presentation. Importantly, polyclonal CD8+ T cells specific for Mtb antigens other than TB10.4 recognized Mtb-infected macrophages in a MHC-restricted manner. As TB10.4 elicits a dominant CD8+ T cell response that poorly recognizes Mtb-infected macrophages, we propose that TB10.4 acts as a decoy antigen. Moreover, it appears that this response overshadows subdominant CD8+ T cell response that can recognize Mtb-infected macrophages. The ability of Mtb to subvert the CD8+ T cell response may explain why CD8+ T cells make a disproportionately small contribution to host defense compared to CD4+ T cells. The selection of Mtb antigens for vaccines has focused on antigens that generate immunodominant responses. We propose that establishing whether vaccine-elicited, Mtb-specific T cells recognize Mtb-infected macrophages could be a useful criterion for preclinical vaccine development.