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Background: Left ventricular stroke work index (LVSWI) and cardiac power index (CPI) account for the haemodynamic load of the left ventricle and are promising prognostic values in cardiogenic shock. However, accurately and non-invasively measuring these parameters during veno-arterial extracorporeal membrane oxygenation (V-A ECMO) is challenging and potentially biased by the extracorporeal circulation. This study aimed to investigate, in an ovine model of cardiogenic shock, whether Pressure-Strain Product (PSP), a novel speckle-tracking echocardiography parameter, (1) can correlate with pressure-volume catheter-based LVSWI and CPI, and (2) can be load-independent during the flow modification of V-A ECMO., Methods: Nine Dorset-cross ewes (51 ± 4 kg) were included. After cardiogenic shock was induced, full support V-A ECMO (X L/min based on 60 mL/kg/min) commenced. At seven time points during 24-h observation, echocardiographic parameters as well as pressure-volume catheter-based LVSWI and CPI were simultaneously measured with X and following X-1 L/min of ECMO flow. PSP was calculated by multiplying global circumferential strain or global radial strain, and mean arterial pressure, for PSPcirc or PSPrad, respectively., Results: PSPcirc showed a stronger correlation with LVSWI (correlation coefficient, CC = .360, p < .001) and CPI (CC = .283, p < .001) than other echocardiographic parameters. The predictability of PSPcirc for pressure-volume catheter-based LVSWI (AUC .82) and CPI (AUC .80) was also higher than other echocardiographic parameters. No statistically significant differences were identified between the two ECMO flow variations in PSPcirc (p = .558)., Conclusions: A novel echocardiographic parameter, PSP, may non-invasively predict pressure-volume catheter-based LVSWI and CPI in a load-independent manner in a cardiogenic shock supported by V-A ECMO., (© 2024 The Author(s). European Journal of Clinical Investigation published by John Wiley & Sons Ltd on behalf of Stichting European Society for Clinical Investigation Journal Foundation.)

Background: Left ventricular stroke work index (LVSWI) and afterload-related cardiac performance (ACP) consider left ventricular (LV) afterload and could be better prognosticators in septic cardiomyopathy. However, their invasive nature prevents their routine clinical applications. This study aimed to investigate (1) whether a proposed speckle-tracking echocardiography parameter, Pressure-Strain Product (PSP), can non-invasively predict catheter-based LVSWI, ACP and serum lactate in an ovine model of septic cardiomyopathy; and (2) whether PSP can distinguish the sub-phenotypes of acute respiratory distress syndrome (ARDS) with or without sepsis-like conditions., Methods: Sixteen sheep with ARDS were randomly assigned to either (1) sepsis-like (n = 8) or (2) non-sepsis-like (n = 8) group. Each ARDS and sepsis-like condition was induced by intravenous infusion of oleic acid and lipopolysaccharide, respectively. Pulmonary artery catheter-based LVSWI (the product of stroke work index, mean arterial pressure and .0136), ACP (the percentage of cardiac output measured to cardiac output predicted as normal) and serum lactate were measured simultaneously with transthoracic echocardiography. Two PSP indices were calculated by multiplying the mean arterial blood pressure and either global circumferential strain (PSPcirc) or radial strain (PSPrad)., Results: PSPcirc showed a significant correlation with LVSWI (r 2  = .66, p < .001) and ACP (r 2  = .82, p < .001) in the sepsis-like group. Although PSP could not distinguish subphenotypes, PSPcirc predicted LVSWI (AUC .86) and ACP (AUC .88), and PSPrad predicted serum lactate (AUC .75) better than LV ejection fraction, global circumferential and radial strain., Conclusions: A novel PSP has the potential to non-invasively predict catheter-based LVSWI and ACP, and was associated with serum lactate in septic cardiomyopathy., (© 2023 The Authors. European Journal of Clinical Investigation published by John Wiley & Sons Ltd on behalf of Stichting European Society for Clinical Investigation Journal Foundation.)

Mortality and morbidity of Acute Respiratory Distress Syndrome (ARDS) are largely unaltered. A possible new approach to treatment of ARDS is offered by the discovery of inflammatory subphenotypes. In an ovine model of ARDS phenotypes, matching key features of the human subphenotypes, we provide an imaging characterization using computer tomography (CT). Nine animals were randomized into (a) OA (oleic acid, hypoinflammatory; n = 5) and (b) OA-LPS (oleic acid and lipopolysaccharides, hyperinflammatory; n = 4). 48 h after ARDS induction and anti-inflammatory treatment, CT scans were performed at high (H) and then low (L) airway pressure. After CT, the animals were euthanized and lung tissue was collected. OA-LPS showed a higher air fraction and OA a higher tissue fraction, resulting in more normally aerated lungs in OA-LPS in contrast to more non-aerated lung in OA. The change in lung and air volume between H and L was more accentuated in OA-LPS, indicating a higher recruitment potential. Strain was higher in OA, indicating a higher level of lung damage, while the amount of lung edema and histological lung injury were largely comparable. Anti-inflammatory treatment might be beneficial in terms of overall ventilated lung portion and recruitment potential, especially in the OA-LPS group., (© 2024. The Author(s).)

Whilst the presence of 2 subphenotypes among the heterogenous Acute Respiratory Distress Syndrome (ARDS) population is becoming clinically accepted, subphenotype-specific treatment efficacy has yet to be prospectively tested. We investigated anti-inflammatory treatment in different ARDS models in sheep, previously shown similarities to human ARDS subphenotypes, in a preclinical, randomized, blinded study. Thirty anesthetized sheep were studied up to 48 h and randomized into: (a) OA: oleic acid (n = 15) and (b) OA-LPS: oleic acid and subsequent lipopolysaccharide (n = 15) to achieve a PaO 2 /FiO 2 ratio of < 150 mmHg. Then, animals were randomly allocated to receive treatment with methylprednisolone or erythromycin or none. Assessed outcomes were oxygenation, pulmonary mechanics, hemodynamics and survival. All animals reached ARDS. Treatment with methylprednisolone, but not erythromycin, provided the highest therapeutic benefit in Ph2 animals, leading to a significant increase in PaO 2 /FiO 2 ratio by reducing pulmonary edema, dead space ventilation and shunt fraction. Animals treated with methylprednisolone displayed a higher survival up to 48 h than all others. In animals treated with erythromycin, there was no treatment benefit regarding assessed physiological parameters and survival in both phenotypes. Treatment with methylprednisolone improves oxygenation and survival, more so in ovine phenotype 2 which resembles the human hyperinflammatory subphenotype., (© 2023. Springer Nature Limited.)

Background: The discovery of biological subphenotypes in acute respiratory distress syndrome (ARDS) might offer a new approach to ARDS in general and possibly targeted treatment, but little is known about the underlying biology yet. To validate our recently described ovine ARDS phenotypes model, we compared a subset of messenger ribonucleic acid (mRNA) markers in leukocytes as reported before to display differential expression between human ARDS subphenotypes to the expression in lung tissue in our ovine ARDS phenotypes model (phenotype 1 (Ph1): hypoinflammatory; phenotype 2 (Ph2): hyperinflammatory)., Methods: We studied 23 anesthetized sheep on mechanical ventilation with observation times between 6 and 24 h. They were randomly allocated to the two phenotypes ( n = 14 to Ph1 and n = 9 to Ph2). At study end, lung tissue was harvested and preserved in RNAlater. After tissue homogenization in TRIzol, total RNA was extracted and custom capture and reporter probes designed by NanoString Technologies were used to measure the expression of 14 genes of interest and the 6 housekeeping genes on a nCounter SPRINT profiler., Results: Among the 14 mRNA markers, in all animals over all time points, 13 markers showed the same trend in ovine Ph2/Ph1 as previously reported in the MARS cohort: matrix metalloproteinase 8, olfactomedin 4, resistin, G protein-coupled receptor 84, lipocalin 2, ankyrin repeat domain 22, CD177 molecule, and transcobalamin 1 expression was higher in Ph2 and membrane metalloendopeptidase, adhesion G protein-coupled receptor E3, transforming growth factor beta induced, histidine ammonia-lyase, and sulfatase 2 expression was higher in Ph1. These expression patterns could be found when different sources of mRNA - such as blood leukocytes and lung tissue - were compared., Conclusion: In human and ovine ARDS subgroups, similar activated pathways might be involved (e.g., oxidative phosphorylation, NF-κB pathway) that result in specific phenotypes., Competing Interests: KW has received research funding from the Julia und Gottfried Bangerter-Rhyner Stiftung, the Prince Charles Hospital Foundation and the Wesley Medical Research Foundation. In addition, she received a Ph.D. scholarship from the University of Queensland. Samantha Livingstone received a Ph.D. scholarship of the Prince Charles Foundation. GL has received research funds, through his affiliated institution from Fisher & Paykel. JS has received an Advance Queensland Industry Research Fellowship and JF received grant funding from Fisher & Paykel, the Prince Charles Hospital Foundation and the Wesley Medical Research Foundation. KW, KH, JM, SL, MP, MB, EW, GL, JF, and JS are members of the Critical Care Research Group., (Copyright © 2022 Wildi, Hyslop, Millar, Livingstone, Passmore, Bouquet, Wilson, LiBassi, Fraser and Suen.)

Use of extracorporeal membrane oxygenation (ECMO) is expanding, however, it is still associated with significant morbidity and mortality. Activation of inflammatory and innate immune responses and hemostatic alterations contribute to complications. Hyperoxia may play a role in exacerbating these responses. Nine ex vivo ECMO circuits were tested using fresh healthy human whole blood, with two oxygen levels: 21% inspired fraction of oxygen (FiO 2 ; mild hyperoxia; n = 5) and 100% FiO 2 (severe hyperoxia; n = 4). Serial blood samples were taken for analysis of platelet aggregometry, leukocyte activation, inflammatory, and oxidative stress markers. ECMO resulted in reduced adenosine diphosphate- (P < .05) and thrombin receptor activating peptide-induced (P < .05) platelet aggregation, as well as increasing levels of the neutrophil activation marker, neutrophil elastase (P = .013). Additionally, levels of the inflammatory chemokine interleukin-8 were elevated (P < .05) and the activity of superoxide dismutase, a marker of oxidative stress, was increased (P = .002). Hyperoxia did not augment these responses, with no significant differences detected between mild and severe hyperoxia. Our ex vivo model of ECMO revealed that the circuit itself triggers a pro-inflammatory and oxidative stress response, however, exposure to supra-physiologic oxygen does not amplify that response. Extended-duration studies and inclusion of an endothelial component could be beneficial in characterizing longer term changes., (© 2020 International Center for Artificial Organ and Transplantation (ICAOT) and Wiley Periodicals LLC.)

There is growing evidence that inflammation underpins many common diseases. Inflammatory/immunomodulatory/immune mediators, such as cytokines, are key modulators of inflammation and mediate both immune cell recruitment and complex intracellular signalling pathways. Ovine models of disease are increasingly utilized in pre-clinical research, however existing methods for measuring cytokine levels are limited. We established and validated enzyme-linked immunosorbent assays (ELISAs) targeting interleukin (IL)-1β, IL-6, IL-8 and IL-10 in sheep plasma. These ELISAs showed high sensitivity and specificity with intra- and inter-assay CV's below 10%, and recovery rates between 82 and 123%. Sensitivity for IL-1β, IL-6, IL-8 and IL-10 were 117.6 pg/mL, 443.1 pg/mL, 30.9 pg/mL, and 64.3 pg/mL, respectively. ELISA test result reproducibility decreased significantly after 12 weeks of plasma storage at -80 °C. Therefore, for accurate cytokine measurements, plasma samples need to be tested within three months of sample collection to account for cytokine protein degradation. These ELISAs offer a reliable and convenient method to identify inflammatory cytokine changes in sheep, allowing key insights into the disease pathogenesis of these ruminants., Competing Interests: Declaration of Competing Interest The authors declare no competing financial interests., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Background: Extracorporeal membrane oxygenation (ECMO) is a life-saving modality used to manage cardiopulmonary failure refractory to conventional medical and surgical therapies. Despite advances in ECMO equipment, bleeding and thrombosis remain significant complications. While the flow rate for ECMO support is well recognized, less is known about the minimum-rate requirements and haemostasis. We investigated the relationship between different ECMO flow rates, and their effect on haemolysis and coagulation., Methods: Ten ex-vivo ECMO circuits were tested using donated, < 24-h-old human whole blood, with two flow rates: high-flow at 4 L/min (normal adult cardiac output; n = 5) and low-flow at 1.5 L/min (weaning; n = 5). Serial blood samples were taken for analysis of haemolysis, von Willebrand factor (vWF) multimers by immunoblotting, rotational thromboelastometry, platelet aggregometry, flow cytometry and routine coagulation laboratory tests., Results: Low-flow rates increased haemolysis after 2 h (p = 0.02), 4 h (p = 0.02) and 6 h (p = 0.02) and the loss of high-molecular-weight vWF multimers (p = 0.01), while reducing ristocetin-induced platelet aggregation (p = 0.0002). Additionally, clot formation times were prolonged (p = 0.006), with a corresponding decrease in maximum clot firmness (p = 0.006)., Conclusions: In an ex-vivo model of ECMO, low-flow rate (1.5 L/min) altered haemostatic parameters compared to high-flow (4 L/min). Observed differences in haemolysis, ristocetin-induced platelet aggregation, high-molecular-weight vWF multimers and clot formation time suggest an increased risk of bleeding complications. Since patients are often on ECMO for protracted periods, extended-duration studies are required to characterise long-term ECMO-induced haemostatic changes.

Thyroid follicles, the functional units of the thyroid gland, are delineated by a monolayer of thyrocytes resting on a continuous basement membrane. The developmental mechanisms of folliculogenesis, whereby follicles are formed by the reorganization of a non-structured mass of non-polarized epithelial cells, are largely unknown. Here we show that assembly of the epithelial basement membrane is crucial for folliculogenesis and is controlled by endothelial cell invasion and by BMP-Smad signaling in thyrocytes. Thyroid-specific Smad1 and Smad5 double-knockout (Smad1/5(dKO)) mice displayed growth retardation, hypothyroidism and defective follicular architecture. In Smad1/5(dKO) embryonic thyroids, epithelial cells remained associated in large clusters and formed small follicles. Although similar follicular defects are found in Vegfa knockout (Vegfa(KO)) thyroids, Smad1/5(dKO) thyroids had normal endothelial cell density yet impaired endothelial differentiation. Interestingly, both Vegfa(KO) and Smad1/5(dKO) thyroids displayed impaired basement membrane assembly. Furthermore, conditioned medium (CM) from embryonic endothelial progenitor cells (eEPCs) rescued the folliculogenesis defects of both Smad1/5(dKO) and Vegfa(KO) thyroids. Laminin α1, β1 and γ1, abundantly released by eEPCs into CM, were crucial for folliculogenesis. Thus, epithelial Smad signaling and endothelial cell invasion promote folliculogenesis via assembly of the basement membrane., (© 2016. Published by The Company of Biologists Ltd.)

The thyroid is a highly vascularized endocrine gland, displaying a characteristic epithelial organization in closed spheres, called follicles. Here we investigate how endothelial cells are recruited into the developing thyroid and if they control glandular organization as well as thyrocytes and C-cells differentiation. We show that endothelial cells closely surround, and then invade the expanding thyroid epithelial cell mass to become closely associated with nascent polarized follicles. This close and sustained endothelial:epithelial interaction depends on epithelial production of the angiogenic factor, Vascular Endothelial Growth Factor-A (VEGF-A), as its thyroid-specific genetic inactivation reduced the endothelial cell pool of the thyroid by > 90%. Vegfa KO also displayed decreased C-cells differentiation and impaired organization of the epithelial cell mass into follicles. We developed an ex vivo model of thyroid explants that faithfully mimicks bilobation of the thyroid anlagen, endothelial and C-cells invasion, folliculogenesis and differentiation. Treatment of thyroid explants at e12.5 with a VEGFR2 inhibitor ablated the endothelial pool and reproduced ex vivo folliculogenesis defects observed in conditional Vegfa KO. In the absence of any blood supply, rescue by embryonic endothelial progenitor cells restored folliculogenesis, accelerated lumen expansion and stimulated calcitonin expression by C-cells. In conclusion, our data demonstrate that, in developing mouse thyroid, epithelial production of VEGF-A is necessary for endothelial cells recruitment and expansion. In turn, endothelial cells control epithelial reorganization in follicles and C-cells differentiation., (Copyright © 2013 Elsevier Inc. All rights reserved.)