Pathophysiological correlations in maedi: a chronic lymphoid interstitial pneumonia of sheep

Maedi is a chronic lymphoid interstitial pneumonia (LIP) of sheep caused by the lentivirus, maedi-visna virus (MW). Following a long prepatent phase maedi progresses to clinical disease characterised by exercise intolerance and dyspnoea. Although maedi is well characterised at a pathological level, physiological studies of the disease have not been undertaken. As a consequence, the nature of the functional abnormality that underlies the clinical disease is unknown, whether there exists measurable functional deficit in the preclinical phase of the disease is unknown and the relationship between lung pathology and functional deficit is unknown. These questions are fundamental to understanding the way in which pathological events ultimately conspire to bring about organ dysfunction and clinical disease. Further, knowledge of the way in which pathology relates to measurable lung dysfunction offers a potential means of assessing the progress and prognosis of this disease. This thesis describes an investigation into the pathophysiological mechanisms responsible for inducing lung functional deficits in maedi.As a prelude to establishing the nature of the functional deficit in maedi, repeated measurements of static lung compliance (Cst), lung distensibility (K), effective alveolar volume (VA,eff) and transfer factor for carbon monoxide (TL,CO,'sb') were made in anaesthetized control sheep, seronegative for MW, over a period of 5 months. This study furnished regression equations and prediction intervals for lung function indices in normal sheep using bodyweight as the independent variable. By comparison with predicted normal values sheep naturally infected with MW had reduced lung volumes and gas diffusing capabilities and increased lung elastic recoil.A pathophysiological study was instigated to identify structural correlates of lung functional deficits. Preliminary investigation involved the quantitative morphometric characterisation of the normal sheep lung. Data from this study indicated that the ratio of fixed to physiological lung volume ranged from 0.49 to 0.59 and that this ratio was positively correlated with the time between euthanasia and inflation fixation of the lungs. Values for tissue volume fraction within the lung parenchyma (Fvt) ranged from 0.18 to 0.25 and values for alveolar surface density (Svt) ranged from 592 to 716 cm2/cm3. Pathophysiological correlations in MW-infected sheep indicated that lung volume and transfer factor measurements were more sensitive indices of pathology than measurements of Cst or K. Transfer factor was reduced even in sheep with minimal histopathology suggesting this index as a sensitive means of assessing this condition. The density of surface forces could not account for variation in K seen in vivo, however tissue factors such as the quantity and functional tone of contractile tissue in the parenchyma, airways or blood vessels may contribute. Given that parenchymal smooth muscle hyperplasia is a pathological feature of maedi, it was hypothesized that this tissue element is responsible for the observed reduction in K.In order to further investigate this relationship, the distribution and morphometric quantitation of a-smooth muscle actin (ASMA) in lung parenchyma from normal and MW-infected 4 sheep was determined and related to in vivo functional measurements. The volume density of ASMA (IVASMA1) was negatively correlated with K and Cst, however partial correlation coefficients indicated that IVASMA' and Fvt were strongly interdependent thus complicating interpretation of the link between Fv'ASMA' and K. In order to separate the influence of dynamic and passive tissue elements, histamine and clenbuterol were administered to normal and MWinfected sheep in an attempt to cause relaxation and contraction of parenchymal contractile tissue. The functional response of the cardiopulmonary system to intravenous infusion of these agents was measured and correlated with Fv'ASMA'. K and Cst were significantly increased following clenbuterol injection, however only the increase in K was correlated with the quantity of Fv'ASMA', and this correlation was negative. These results could be explained if the site of action of clenbuterol was not the contractile tissue at the level of the alveolar ducts, but rather that which surrounds conducting airways.The dose of histamine required to lower dynamic compliance to 65% of baseline values was negatively correlated with Fv'ASMA' and the attendant percentage change in K was positively correlated with Fv'ASMA'. These findings support the contention that parenchymal contractile tissue is of functional relevance and capable of regulating overall lung elastic properties.Maedi is a naturally occurring disease in sheep in which the aetiologic agent and target cell is known and in which the pathology is well characterised. As such it has potential as a model for LIP associated with human immunodeficiency virus infection in children and adults. The present study has both served to establish the functional characteristics of this disease and indicate structural correlates of observed functional deficits. Moreover, evidence is presented to suggest that the observed reduction in lung distensibility in maedi is a consequence of increased tissue forces associated with the parenchymal smooth muscle hyperplasia that is a feature of this disease

Local lung responses following endobronchial elastase and lipopolysaccharide instillation in sheep

Chronic lipopolysaccharide (LPS) exposure may contribute to the pathogenesis of a number of lung diseases including COPD and emphysema. We sought to develop a large- animal model of emphysema using repeated LPS administration into sheep lung segments. An experimental protocol was designed to facilitate comparisons with elastase-treated and control segments within the same lung of individual sheep. Histopathologic evaluation of segments treated with LPS demonstrated low-grade inflammation characterized by an increase in the number of intra-alveolar macrophages and lymphocytes. Treated segments demonstrated a significant reduction in airspace surface area (ASA), an increase in percent disrupted alveolar attachments and the distance between normal alveolar attachments, and a reduction in the number of normal alveolar attachments surrounding nonrespiratory bronchioles. Coefficient of variation of individual ASA measurements in elastase-treated segments was indicative of a heterogeneous parenchymal response, in contrast to that associated with chronic LPS treatment. Our results demonstrate that chronic LPS treatment of individual lung segments in sheep induces microscopic emphysema qualitatively and quantitatively consistent with both accepted pathologic definitions of this condition and with that produced by airway instillation of elastolytic enzymes. Development of this phenotype is associated with evidence of downregulated activation of transforming growth factor beta

The Partonic Nature of Instantons

In both Yang-Mills theories and sigma models, instantons are endowed with degrees of freedom associated to their scale size and orientation. It has long been conjectured that these degrees of freedom have a dual interpretation as the positions of partonic constituents of the instanton. These conjectures are usually framed in d=3+1 and d=1+1 dimensions respectively where the partons are supposed to be responsible for confinement and other strong coupling phenomena. We revisit this partonic interpretation of instantons in the context of d=4+1 and d=2+1 dimensions. Here the instantons are particle-like solitons and the theories are non-renormalizable. We present an explicit and calculable model in d=2+1 dimensions where the single soliton in the CP^N sigma-model can be shown to be a multi-particle state whose partons are identified with the ultra-violet degrees of freedom which render the theory well-defined at high energies. We introduce a number of methods which reveal the partons inside the soliton, including deforming the sigma model and a dual version of the Bogomolnyi equations. We conjecture that partons inside Yang-Mills instantons hold the key to understanding the ultra-violet completion of five-dimensional gauge theories.Comment: 28 pages. v3: extra references and comments. Mathematica notebooks for the figures can be downloaded from http://www.damtp.cam.ac.uk/user/dt281/parton.htm

ADHM and the 4d quantum Hall effect

Yang-Mills instantons are solitonic particles in d=4+1 dimensional gauge theories. We construct and analyse the quantum Hall states that arise when these particles are restricted to the lowest Landau level. We describe the ground state wavefunctions for both Abelian and non-Abelian quantum Hall states. Although our model is purely bosonic, we show that the excitations of this 4d quantum Hall state are governed by the Nekrasov partition function of a certain five dimensional supersymmetric gauge theory with Chern-Simons term. The partition function can also be interpreted as a variant of the Hilbert series of the instanton moduli space, counting holomorphic sections rather than holomorphic functions. It is known that the Hilbert series of the instanton moduli space can be rewritten using mirror symmetry of 3d gauge theories in terms of Coulomb branch variables. We generalise this approach to include the effect of a five dimensional Chern-Simons term. We demonstrate that the resulting Coulomb branch formula coincides with the corresponding Higgs branch Molien integral which, in turn, reproduces the standard formula for the Nekrasov partition function

Dietary fibre supplementation enhances radiotherapy tumour control and alleviates intestinal radiation toxicity

Acknowledgements We thank Professor William Kim (University of North Carolina, Chapel Hill) for his generous gift of the UPPL1591 cell line. We thank Dr. Mark Hill (Department of Oncology, University of Oxford) for assistance with irradiation procedures, and Dr. Jia-Yu Ke and Dr. Vijay Indukuri (Research Diets, Inc.) for formulation of the mouse diets. We thank Dr. Graham Horgan (James Hutton Research Institute, Aberdeen) for statistical advice. We thank Grampian Biorepository at Aberdeen Royal Infirmary for providing the faecal samples from cancer patients.Peer reviewe

Dietary fibre supplementation enhances radiotherapy tumour control and alleviates intestinal radiation toxicity.

Non-toxic approaches to enhance radiotherapy outcomes are beneficial, particularly in ageing populations. Based on preclinical findings showing that high-fibre diets sensitised bladder tumours to irradiation by modifying the gut microbiota, along with clinical evidence of prebiotics enhancing anti-cancer immunity, we hypothesised that dietary fibre and its gut microbiota modification can radiosensitise tumours via secretion of metabolites and/or immunomodulation. We investigated the efficacy of high-fibre diets combined with irradiation in immunoproficient C57BL/6 mice bearing bladder cancer flank allografts. Psyllium plus inulin significantly decreased tumour size and delayed tumour growth following irradiation compared to 0.2% cellulose and raised intratumoural CD8+ cells. Post-irradiation, tumour control positively correlated with Lachnospiraceae family abundance. Psyllium plus resistant starch radiosensitised the tumours, positively correlating with Bacteroides genus abundance and increased caecal isoferulic acid levels, associated with a favourable response in terms of tumour control. Psyllium plus inulin mitigated the acute radiation injury caused by 14 Gy. Psyllium plus inulin increased caecal acetate, butyrate and propionate levels, and psyllium alone and psyllium plus resistant starch increased acetate levels. Human gut microbiota profiles at the phylum level were generally more like mouse 0.2% cellulose profiles than high fibre profiles. These supplements may be useful in combination with radiotherapy in patients with pelvic malignancy

VGLL3 operates via TEAD1, TEAD3 and TEAD4 to influence myogenesis in skeletal muscle

© 2019. Published by The Company of Biologists Ltd.Peer reviewedPublisher PD

Gene Expression Changes Associated with the Airway Wall Response to Injury

Understanding the way in which the airway heals in response to injury is fundamental to dissecting the mechanisms underlying airway disease pathology. As only limited data is available in relation to the in vivo characterisation of the molecular features of repair in the airway we sought to characterise the dynamic changes in gene expression that are associated with the early response to physical injury in the airway wall.We profiled gene expression changes in the airway wall using a large animal model of physical injury comprising bronchial brush biopsy in anaesthetised sheep. The experimental design featured sequential studies in the same animals over the course of a week and yielded data relating to the response at 6 hours, and 1, 3 and 7 days after injury. Notable features of the transcriptional response included the early and sustained preponderance of down-regulated genes associated with angiogenesis and immune cell activation, selection and differentiation. Later features of the response included the up-regulation of cell cycle genes at d1 and d3, and the latter pronounced up-regulation of extracellular matrix-related genes at d3 and d7.It is possible to follow the airway wall response to physical injury in the same animal over the course of time. Transcriptional changes featured coordinate expression of functionally related genes in a reproducible manner both within and between animals. This characterisation will provide a foundation against which to assess the perturbations that accompany airway disease pathologies of comparative relevance

The safety profile of a cationic lipid-mediated cystic fibrosis gene transfer agent following repeated monthly aerosol administration to sheep

Clinically effective gene therapy for Cystic Fibrosis has been a goal for over 20 years. A plasmid vector (pGM169) that generates persistent expression and reduced host inflammatory responses in mice has raised prospects for translation to the clinic. The UK CF Gene Therapy Consortium is currently evaluating long-term repeated delivery of pGM169 complexed with the cationic lipid GL67A in a large Multidose Trial. This regulatory-compliant evaluation of aerosol administration of nine doses of pGM169/GL67A at monthly intervals, to the sheep lung, was performed in preparation for the Multidose Trial. All sheep tolerated treatment well with no adverse effects on haematology, serum chemistry, lung function or histopathology. Acute responses were observed in relation to bronchoalveolar cellularity comprising increased neutrophils and macrophage numbers 1 day post-delivery but these increases were transient and returned to baseline. Importantly there was no cumulative inflammatory effect or lung remodelling with successive doses. Molecular analysis confirmed delivery of pGM169 DNA to the airways and pGM169-specific mRNA was detected in bronchial brushing samples at day 1 following doses 1, 5 and 9. In conclusion, nine doses of pGM169/GL67A were well tolerated with no significant evidence of toxicity that would preclude adoption of a similar strategy in CF patients