Airway macrophage-intrinsic TGF-ß1 regulates pulmonary immunity during early-life allergen exposure.

BACKGROUND: Early life represents a major risk window for asthma development. However, the mechanisms controlling the threshold for establishment of allergic airway inflammation in early life are incompletely understood. Airway macrophages (AMs) regulate pulmonary allergic responses and undergo TGF-ß-dependent postnatal development, but the role of AM maturation factors such as TGF-ß in controlling the threshold for pathogenic immune responses to inhaled allergens remains unclear. OBJECTIVE: Our aim was to test the hypothesis that AM-derived TGF-ß1 regulates pathogenic immunity to inhaled allergen in early life. METHODS: Conditional knockout (Tgfb1ΔCD11c) mice, with TGF-ß1 deficiency in AMs and other CD11c+ cells, were analyzed throughout early life and following neonatal house dust mite (HDM) inhalation. The roles of specific chemokine receptors were determined by using in vivo blocking antibodies. RESULTS: AM-intrinsic TGF-ß1 was redundant for initial population of the neonatal lung with AMs, but AMs from Tgfb1ΔCD11c mice failed to adopt a mature homeostatic AM phenotype in the first weeks of life. Evidence of constitutive TGF-ß1 signaling was also observed in pediatric human AMs. TGF-ß1-deficient AMs expressed enhanced levels of monocyte-attractant chemokines, and accordingly, Tgfb1ΔCD11c mice exposed to HDM throughout early life accumulated CCR2-dependent inflammatory CD11c+ mononuclear phagocytes into the airway niche that expressed the proallergic chemokine CCL8. Tgfb1ΔCD11c mice displayed augmented TH2, group 2 innate lymphoid cell, and airway remodeling responses to HDM, which were ameliorated by blockade of the CCL8 receptor CCR8. CONCLUSION: Our results highlight a causal relationship between AM maturity, chemokines, and pathogenic immunity to environmental stimuli in early life and identify TGF-ß1 as a key regulator of this.

A T cell-myeloid IL-10 axis regulates pathogenic IFN-γ-dependent immunity in a mouse model of type 2-low asthma.

BACKGROUND: Although originally defined as a type 2 (T2) immune-mediated condition, non-T2 cytokines, such as IFN-γ and IL-17A, have been implicated in asthma pathogenesis, particularly in patients with severe disease. IL-10 regulates TH cell phenotypes and can dampen T2 immunity to allergens, but its functions in controlling non-T2 cytokine responses in asthmatic patients are unclear. OBJECTIVE: We sought to determine how IL-10 regulates the balance of TH cell responses to inhaled allergen. METHODS: Allergic airway disease was induced in wild-type, IL-10 reporter, and conditional IL-10 or IL-10 receptor α (IL-10Rα) knockout mice by means of repeated intranasal administration of house dust mite (HDM). IL-10 and IFN-γ signaling were disrupted by using blocking antibodies. RESULTS: Repeated HDM inhalation induced a mixed IL-13/IL-17A response and accumulation of IL-10-producing forkhead box P3-negative effector CD4+ T cells in the lungs. Ablation of T cell-derived IL-10 increased the IFN-γ and IL-17A response to HDM, reducing IL-13 levels and airway eosinophilia without affecting IgE levels or airway hyperresponsiveness. The increased IFN-γ response could be recapitulated by IL-10Rα deletion in CD11c+ myeloid cells or local IL-10Rα blockade. Disruption of the T cell-myeloid IL-10 axis resulted in increased pulmonary monocyte-derived dendritic cell numbers and increased IFN-γ-dependent expression of CXCR3 ligands by airway macrophages, which is suggestive of a feedforward loop of TH1 cell recruitment. Augmented IFN-γ responses in the HDM allergic airway disease model were accompanied by increased disruption of airway epithelium, which was reversed by therapeutic blockade of IFN-γ. CONCLUSIONS: IL-10 from effector T cells signals to CD11c+ myeloid cells to suppress an atypical and pathogenic IFN-γ response to inhaled HDM.

Impact of Fire Arms Training in a Virtual Reality Environment on Occupational Performance (Marksmanship) in a Polytrauma Population.

INTRODUCTION: Polytrauma, to include major limb amputation, in a military population presents unique rehabilitation challenges with the overarching goal of restoring function leading to the primary question, "Is this Service Member (SM) capable of returning to duty following rehabilitation?" The US military has a vested interest in maximizing injured SMs occupational performance to allow for return to duty. The purpose of this report is to describe marksmanship (shot grouping and weapon qualification) and return to duty outcomes following a course of VRE-based firearm training in a polytrauma patient population. METHODS: The medical records, stored in the Armed Forces Health Longitudinal Technology Application (AHLTA), of all patients who received rehabilitative care at the Center for the Intrepid (CFI) to include VRE-based firearms training between 01OCT2015 and 01AUG2016 were manually reviewed for inclusion. Subjects included all adult (18 years and older) SMs (active duty at time of admission) with a diagnosis of polytrauma who had been referred to and treated (received additional services such as physical and or occupational therapy) at the CFI. Approval for this research was received from the Brooke Army Medical Center Department of Clinical Investigation Office of the Institutional Review Board. RESULTS: Medical records of 30 SMs with a polytrauma diagnosis met the inclusion criteria. Mean shot group sizes for the M9 and M4 weapon decreased between initial and post training time points for the M9 zero (p = 0.009) and M4 zero (p = 0.020). There was no significant difference between initial and post training time points at the other shooting distances with either weapon. There was an 89% qualification rate for both the M9 (n = 18) and M4 (n = 19) weapons for those who attempted qualification; 43% of the population (n = 13) did not attempt qualification with either weapon. CONCLUSION: SMs with polytrauma demonstrated a high rate of weapon qualification (accuracy) following VRE-based firearm training. Shot group size (precision) at short distances with a M9 pistol and M4 rifle also improved with training. While overall marksmanship appeared to improve, high return to duty rates were not directly related to firearm training or marksmanship. Future efforts need to focus on consistent clinical documentation of firearm training procedure and the establishment of psychometric properties for marksmanship outcome measures.

Pulmonary Group 2 Innate Lymphoid Cell Phenotype Is Context Specific: Determining the Effect of Strain, Location, and Stimuli.

Group 2 innate lymphoid cells (ILC2s) are enriched at mucosal sites, including the lung, and play a central role in type 2 immunity and maintaining tissue homeostasis. As a result, since their discovery in 2010, research into ILC2s has increased markedly. Numerous strategies have been used to define ILC2s by flow cytometry, often utilizing different combinations of surface markers despite their expression being variable and context-dependent. In this study, we sought to generate a comprehensive characterization of pulmonary ILC2s, identifying stable and context specific markers from different pulmonary compartments following different airway exposures in different strains of mice. Our analysis revealed that pulmonary ILC2 surface marker phenotype is heterogeneous and is influenced by mouse strain, pulmonary location, in vivo treatment/exposure and ex vivo stimulation. Therefore, we propose that a lineage negative cell expressing CD45 and Gata3 defines an ILC2, and subsequent surface marker expression should be used to describe their phenotype in context-specific scenarios.

Functional Capacity Evaluation-Military: Program Description and Case Series.

A functional capacity evaluation (FCE) evaluates the ability of an individual to perform activities related to employment. There is no FCE specific to the military population; therefore, a FCE for the military population (FCE-M) was developed to evaluate an injured service member's (SM) ability to return to duty. The FCE-M is herein described along with descriptions of three active duty SMs who completed the evaluation. The three SMs completed all categories of the FCE-M with the first two cases achieving a work-level classification of Heavy-Very Heavy and the third a classification of Medium-Heavy. The FCE-M provides a systematic assessment of performance of highly specified military tasks and may provide value in assessing readiness for returning to duty.

Functional expression of a bovine major histocompatibility complex class I gene in transgenic mice.

Major histocompatibility complex (MHC) class I restricted cellular immune responses play an important role in immunity to intracellular pathogens. By binding antigenic peptides and presenting them to T cells, class I molecules impose significant selection on the targets of immune responses. Candidate vaccine antigens for cellular immune responses should therefore be analysed in the context of MHC class I antigen presentation. Transgenic mice expressing human MHC (HLA) genes provide a useful model for the identification of potential cytotoxic T lymphocyte (CTL) antigens. To facilitate the analysis of candidate CTL vaccines in cattle, we have produced transgenic mice expressing a common bovine MHC (BoLA) class I allele. The functional BoLA-A11 gene, carried on a 7 kb genomic DNA fragment, was used to make transgenic mice by pronuclear microinjection. Three transgenic mouse lines carrying the BoLA-A11 gene were established. Expression of the BoLA-A11 gene was found in RNA and the A11 product could be detected on the surface of spleen and blood cells. Functional analysis of the A11 transgene product, and its ability to act as an antigen presenting molecules in the mouse host will be discussed.

Progress toward controlling in vivo fibrillating sheep atria using a nonlinear-dynamics-based closed-loop feedback method.

We describe preliminary experiments on controlling in vivo atrial fibrillation using a closed-loop feedback protocol that measures the dynamics of the right atrium at a single spatial location and applies control perturbations at a single spatial location. This study allows investigation of control of cardiac dynamics in a preparation that is physiologically close to an in vivo human heart. The spatial-temporal response of the fibrillating sheep atrium is measured using a multi-channel electronic recording system to assess the control effectiveness. In an attempt to suppress fibrillation, we implement a scheme that paces occasionally the cardiac muscle with small shocks. When successful, the inter-activation time interval is the same and electrical stimuli are only applied when the controller senses that the dynamics are beginning to depart from the desired periodic rhythm. The shock timing is adjusted in real time using a control algorithm that attempts to synchronize the most recently measured inter-activation interval with the previous interval by inducing an activation at a time projected by the algorithm. The scheme is "single-sided" in that it can only shorten the inter-activation time but not lengthen it. Using probability distributions of the inter-activation time intervals, we find that the feedback protocol is not effective in regularizing the dynamics. One possible reason for the less-than-successful results is that the controller often attempts to stimulate the tissue while it is still in the refractory state and hence it does not induce an activation. (c) 2002 American Institute of Physics.

An ionically based mapping model with memory for cardiac restitution.

Many features of the sequence of action potentials produced by repeated stimulation of a patch of cardiac muscle can be modeled by a 1D mapping, but not the full behavior included in the restitution portrait. Specifically, recent experiments have found that (i) the dynamic and S1-S2 restitution curves are different (rate dependence) and (ii) the approach to steady state, which requires many action potentials (accommodation), occurs along a curve distinct from either restitution curve. Neither behavior can be produced by a 1D mapping. To address these shortcomings, ad hoc 2D mappings, where the second variable is a "memory" variable, have been proposed; these models exhibit qualitative features of the relevant behavior, but a quantitative fit is not possible. In this paper we introduce a new 2D mapping and determine a set of parameters for it that gives a quantitatively accurate description of the full restitution portrait measured from a bullfrog ventricle. The mapping can be derived as an asymptotic limit of an idealized ionic model in which a generalized concentration acts as a memory variable. This ionic basis clarifies how the present model differs from previous models. The ionic basis also provides the foundation for more extensive cardiac modeling: e.g., constructing a PDE model that may be used to study the effect of memory on propagation. The fitting procedure for the mapping is straightforward and can easily be applied to obtain a mathematical model for data from other experiments, including experiments on different species.

Reproducing cardiac restitution properties using the Fenton-Karma membrane model.

Modern models of cardiac membranes are often highly complex and computationally expensive, particularly when used in long simulations of spatially extended models of cardiac tissue. Therefore, there is a need for simpler membrane models that preserve the features of the complex models deemed important. This communication describes an empirical procedure that was used to choose the parameters of the three-variable Fenton-Karma (FK3V) model to reproduce the restitution properties of the Courtemanche-Ramirez-Nattel model of atrial tissue. The resulting parameter values for the FK3V model and the sensitivity table for all its parameters are provided. Thus, this study gives insight into the behavior of the FK3V model and the effect of its parameters on restitution properties.

Bistability and correlation with arrhythmogenesis in a model of the right atrium.

Rapid pacing is an important tool for understanding cardiac arrhythmias. A recent experiment involving rapid pacing of sheep atria indicated that the initiation of atrial arrhythmias may be related to the 1:1/2:1 bistability. To elucidate the mechanism of this relation, this study applied the pacing protocol from the sheep study to an idealized model of the right atrium. The model included all major anatomical features, the sino-atrial node, and the regional differences in the action potential duration (APD). A pacing protocol was applied, in which the basic cycle length (BCL) was decreased in steps of 10 ms until the response switched to 2:1, then BCL was increased. The 1:1-to-2:1 transitions occurred at shorter BCLs than the 2:1-to-1:1 transitions yielding a global bistability window of 60ms. As in the sheep study, idiopathic waves were observed at BCLs within or near the bistability window. The model was used to quantify the types, prevalence, and persistence of idiopatic waves, study their initiation and termination, and relate them to the model components. The results demonstrate that idiopatic waveforms move with the shift of the bistability window and that they disappear when bistability is eliminated. Thus, this modeling study supports causal relationship between the 1:1/2:1 bistability and the initiation of arrhythmias.

A membrane model of electrically remodelled atrial myocardium derived from in vivo measurements.

AIMS: Contemporary ionic-based membrane models are computationally expensive and are not intended to match the properties of a given experimental preparation. The aim of this work was to use measured restitution properties of electrically remodelled atrial tissue to develop a simplified membrane model based on the Fenton-Karma (FK) equations amenable to large-scale simulation of chronic atrial fibrillation (CAF). METHODS: Two membrane models, the FK-CAF and FK-CNTRL parameter sets, were developed to match action potential duration (APD) and conduction velocity (CV) restitution properties of rapid-pacing-induced electrically remodelled sheep atria and healthy atria, respectively. The models were tested by inducing reentry in a two-dimensional anisotropic monodomain and comparing the resulting cycle lengths (CL) with measured CLs. RESULTS: Parameters for the FK models were obtained that reproduced APD and CV restitution properties measured in the CAF and healthy sheep atria. Using the FK-CAF parameters, reentry was sustained in a 2.5 by 2.5 cm sheet with a CL = 91.0 +/- 3.0 ms. Reentry (CL = 113.2 +/- 5.2 ms) could only be sustained in the FK-CNTRL model after the tissue was first activated at a fast rate (136.5 ms). CONCLUSIONS: The FK-CAF model is shown to approximate the restitution properties of remodelled sheep atria and can be used to simulate reentry with short CLs similar to those measured during AF episodes.