Idiopathic pulmonary fibrosis (IPF) is an irreversible disease of unknown etiology that involves progressive scarring of the lung tissue, leading to respiratory failure and death.1 IPF is thought to develop from repetitive lung injury and aberrant wound healing that leads to the generation of fibrous tissue rather than restoration of normal tissue.2 It has been suggested in mice that vascular leak after lung injury contributes to the development of lung fibrosis.2,3 Gadofosveset is an intravascular enhancing, gadolinium-based contrast agent used with magnetic resonance imaging (MRI) to assess a variety of biological processes in vivo because it can reversibly bind to albumin.13-14 Gadofosveset has been used to assess endothelial permeability and function, as it diffuses through the vessel walls via leaky neovessels and damaged endothelium.15 Our research group has developed a new method to assess disease activity in IPF patients using gadofosveset-enhanced lung MRI. In unpublished work, we have demonstrated that this technique can be used to generate an albumin extravasation index (AEI), and we have found that this is significantly and diffusely increased in the lung of patients with idiopathic pulmonary fibrosis compared to healthy controls.16 The AEI is a measure of the change in signal intensity post-contrast minus pre-contrast in predefined regions of interest (ROIs) in the lung parenchyma divided by post- minus pre-contrast signal intensity in the ROI in the aorta. In this study, we compared the AEI in patients with IPF to healthy control (HC) subjects and evaluated the correlation between the AEI and high-resolution computed tomography (HRCT) and pulmonary function testing (PFT). We found that IPF subjects had increased AEI values compared with HC subjects. While not statistically significant, AEI was more strongly correlated with fibrosis (interstitial abnormalities) than ground-glass (alveolar abnormalities) on HRCT. Furthermore, there was a possible correlation between AEI and change in percent predicted forced expiratory volume in the first second (FEV1), forced vital capacity (FVC), and diffusion capacity of carbon monoxide adjusted for hemoglobin (DLCO) [Hb]. Our results demonstrate that AEI calculations from gadofosveset-enhanced lung MRI are a surrogate measure of vascular leak and can potentially serve as an alternative method for predicting the clinical course and severity of IPF through its correlation with fibrosis on HRCT and pulmonary function.

Background Idiopathic pulmonary fibrosis (IPF) is a devastating form of chronic lung injury of unknown aetiology characterised by progressive lung scarring. A diagnosis of definite IPF requires High Resolution Computed Tomography (HRCT) appearances indicative of usual interstitial pneumonia (UIP), or in patients with 'possible UIP' CT appearances, histological confirmation of UIP. However the proportion of such patients that undergo SLB varies, perhaps due to a perception of risk of biopsy and additive diagnostic value of biopsy in individual patients. We hypothesised that an underlying UIP pathological pattern may result in increased risk of death and aimed to explore this by comparing the risk of SLB in suspected idiopathic interstitial pneumonia, stratified according to HRCT appearance. Additionally we sought to determine the positive-predictive value of biopsy to diagnose IPF in patients with 'possible UIP HRCT' in our population. In patients with possible UIP who are not biopsied, the clinical value of bronchoalveolar lavage (BAL) is uncertain. We aimed to prospectively study the diagnostic and prognostic value of BAL differential cell count (DCC) in suspected IPF and determine the feasibility of repeat BAL and the relationship between DCC and disease progression in two successive BALs. We hypothesised that BAL DCC between definite and possible IPF was different and that baseline DCC and change in BAL DCC predicted disease progression. Alveolar macrophages (AMs) are an integral part of the lung's reparative mechanism following injury, however in IPF they contribute to pathogenesis by releasing pro-fibrotic mediators promoting fibroblast proliferation and collagen deposition. Expansion of novel subpopulations of pulmonary monocyte-like cells (PMLCs) has been reported in inflammatory lung disease. We hypothesised that a distinct AM polarisation phenotype would be associated with disease progression. We aimed to perform detailed phenotyping of AM and PMLCs in BAL in IPF patients. Several prognostic scoring systems and biomarkers have been described to predict disease progression in IPF but most were derived from clinical trial patients or tertiary referral centres and none have been validated in separate cohorts. We aimed to identify a predictive tool for disease progression utilising physiological, HRCT and serum biomarkers in a unique population of incident treatment naïve IPF patients. Methods Between 01/01/07 and 31/12/13, 611 consecutive incident patients with suspected idiopathic interstitial pneumonia (IIP) presented to the Edinburgh lung fibrosis clinic. Of these patients 222 underwent video-assisted thoracoscopic lung biopsy and histological pattern was determined according to ATS/ERS criteria. Post-operative mortality and complication rates were examined. Fewer than 2% received IPF-directed therapy and less than 1% of the cohort were lost to follow-up. Disease progression was defined as death or ≥10% decline in VC within 12 months of BAL. Cells were obtained by BAL and a panel of monoclonal antibodies; CD14, CD16, CD206, CD71, CD163, CD3, CD4, CD8 and HLA-DR were used to quantify and selectively characterise AMs, resident PMLCs, inducible PMLCs, neutrophils and CD4+/CD8+ T-cells using flow cytometry. Classical, intermediate and non-classical monocyte subsets were also quantified in peripheral blood. Potential biomarkers (n=16) were pre-selected from either previously published studies of IPF biomarkers or our hypothesis-driven profiling. Linear logistic regression was used on each predictor separately to assess its importance in terms of p-value of the associated weight, and the top two variables were used to learn a decision tree. Results Based on the 2011 ATS/ERS criteria, 87 patients were categorised as 'definite UIP', of whom 3 underwent SLB for clinical indications. IPF was confirmed in all 3 patients based on 2013 ATS/ERS/JRS/ALAT diagnostic criteria. 222 patients were diagnosed with 'possible UIP'; 55 underwent SLB, IPF was subsequently diagnosed in 37 patients, 4 were diagnosed with 'probable IPF' and 14 were considered 'not IPF'. In this group, 30 patients were aged 65 years or over and 25/30 (83%) had UIP on biopsy. 306 patients had HRCTs deemed 'inconsistent with UIP', SLB was performed in 168 patients. Post6 operative 30-day mortality was 2.2% overall, and 7.3% in the 'possible UIP' HRCT group. Patients with 'definite IPF' based on HRCT and SLB appearances had significantly better outcomes than patients with 'definite UIP' on HRCT alone (P=0.008, HR 0.44 (95% CI 0.240 to 0.812)). BAL DCC was not different between definite and possible UIP groups, but there were significant differences with the inconsistent with UIP group. In the 12 months following BAL, 33.3% (n=7/21) of patients in the definite UIP group and 29.5% (n=18/61) in the possible UIP group had progressed. There were no significant differences in BAL DCC between progressor and non-progressor groups. Mortality in patients with suspected IPF and a BAL DCC consistent with IPF was no different to those with a DCC inconsistent with IPF (P=0.425, HR 1.590 (95% CI 0.502 to 4.967)). There was no difference in disease progression in either group (P=0.885, HR 1.081 (95% CI 0.376 to 3.106)). There was no statistically significant difference in BAL DCC at 0 and 12 months in either group. There was no significant change in DCC between 0 and 12 month BALs between progressors and non-progressors. Repeat BAL was well tolerated in almost all patients. There was 1 death within 1 month of a first BAL and 1 death within 1 month of a second BAL; both were considered 'probably procedure-related'. AM CD163 and CD71 (transferrin receptor) expression were significantly different between groups (P < 0.0001), with significant increases in the IPF group vs non fibrotic ILD (P < 0.0001) and controls (P < 0.0001 and P < 0.001 respectively). CD71 expression was also significantly increased in the IPF progressor vs non-progressor group (P < 0.0001) and patients with high CD71 expression had significantly poorer survival than the CD71low group (P=0.040, median survival 40.5 and 75.6 months respectively). CD206 (mannose receptor) expression was also significantly higher in the IPF progressor vs non-progressor group (P=0.034). There were no differences in baseline BAL neutrophil, eosinophil or lymphocyte percentages between IPF progressor or non-progressor groups. The percentage of rPMLCs was significantly increased in BAL fluid cells of IPF patients compared to those with non-fibrotic ILD (P < 0.0001) and healthy controls (P < 0.05). Baseline rPMLC percentage was significantly higher in IPF progressors vs IPF non-progressors (P=0.011). Baseline BAL iPMLC:rPMLC ratio was also significantly different between IPF progressor and non-progressor groups (P=0.011). Disease progression was confidently predicted by a combination of clinical and serological variables. In our cohort we identified a predictive tool based on two key parameters, one a measure of lung function and one a single serum biomarker. Both parameters were entered into a decision tree, and when applied to our cohort yielded a sensitivity of 86.4%, specificity of 92.3%, positive predictive value of 90.5% and negative predictive value of 88.9%. We also applied previously reported predictive tools such as the GAP Index, du Bois score and CPI Index to the Edinburgh IPF cohort. Conclusions SLB can be of value in the diagnosis of ILD, however perhaps due to the perceived risks associated with the procedure, only a small percentage of patients undergo SLB despite recommendations that patients have histological confirmation of the diagnosis. Advanced age is a strong predictor for IPF, and in our cohort 83% of patients aged over 65 years with 'possible UIP' HRCT appearances, had UIP on biopsy. BAL and repeat BAL in IPF is feasible and safe (< 1.5% mortality). Of those that underwent repeat BAL, disease progression was not associated with a change in DCC. However, 22% of lavaged patients died or were deemed too frail to undergo a second procedure at 12 months. These data emphasise the importance of BAL in identifying a novel human AM polarisation phenotype in IPF. Our data suggests there is a distinct relationship between AM subtypes, cell-surface expression markers, PMLC subpopulations and disease progression in IPF. This may be utilised to investigate new targets for future therapeutic strategies. / Disease progression in IPF can be predicted by a combination of clinical variables and serum biomarker profiling. We have identified a unique prediction model, when applied to our locally referred, incident, treatment naïve cohort can confidently predict disease progression in IPF. IPF is a heterogeneous disease and there is a definite clinical need to identify 'personalised' prognostic biomarkers which may in turn lead to novel targets and the advent of personalised medicines.

This work aims to investigate the flexural behaviour of continuous hybrid reinforced concrete T-beams (HRCT). The investigations consist of three parts; the computational part, the experimental part and the finite element analysis. The computational part included two parts, the first one is developing an analytical programme using MATLAB software to investigate the moment-curvature behaviour of HRCT-beams and to design the experimental specimens. This was followed by the experimental part, where six full-scale reinforced concrete continuous T beams were prepared and tested. One beam was reinforced with glass fibre reinforced polymer (GFRP) bars while the other five beams were reinforced with a different combination of GFRP and steel bars. The ratio of GFRP to steel reinforcement at both mid-span and middle-support sections was the main parameter investigated. The results showed that adding steel reinforcement to GFRP reinforced concrete T-beams improves the axial stiffness, ductility and serviceability in terms of crack width and deflection control. However, the moment redistribution at failure was limited because of the early yielding of steel reinforcement at the beam section that did not reach its moment capacity and could still carry more loads due to the presence of FRP reinforcement. The second part of the computational part included the comparison between the experimental results with the ultimate moment prediction of ACI 440.2R-17, and with the existing theoretical equations for moment capacity, load capacity, and deflection prediction. It was found that the ACI 440.2R-17 design code equations reasonably estimated the moment capacity of both mid-span and middle-support sections and consequently predicted the load capacity of the HRCT-beams based on fully ductile behaviour. However, Qu's and Safan's equations underestimated the predicted moment and load-capacity of HRCT-beams. Also, Bischoff's and Yoon's models underestimated the deflection at all stages of the load for both GFRP and HRCT- beams. For the numerical part, a three-dimensional finite element model has been developed using ABAQUS software to examine the behaviour of HRCT-beams. The experimental results were used to validate the accuracy of the FEM, where an acceptable agreement between the simulated and experimental results was observed. Accordingly, the model was used to predict the structural behaviour of continuous HRCT-beams by testing different parameters.