Role of circulating angiogenin levels in portal hypertension and TIPS

Background Pathogenesis of portal hypertension is multifactorial and includes pathologic intrahepatic angiogenesis, whereby TIPS insertion is an effective therapy of portal hypertension associated complications. While angiogenin is a potent contributor to angiogenesis in general, little is known about its impact on TIPS function over time. Methods In a total of 118 samples from 47 patients, angiogenin concentrations were measured in portal and inferior caval vein plasma at TIPS insertion (each blood compartment n = 23) or angiographic intervention after TIPS (each blood compartment n = 36) and its relationship with patient outcome was investigated. Results Angiogenin levels in the inferior caval vein were significantly higher compared to the portal vein (P = 0.048). Ten to 14 days after TIPS, inferior caval vein angiogenin level correlated inversely with the portal systemic pressure gradient (P<0.001), measured invasively during control angiography. Moreover, patients with TIPS revision during this angiography, showed significantly lower angiogenin level in the inferior caval vein compared to patients without TIPS dysfunction (P = 0.01). Conclusion In cirrhosis patients with complications of severe portal hypertension, circulating levels of angiogenin are derived from the injured liver. Moreover, angiogenin levels in the inferior caval vein after TIPS may predict TIPS dysfunction.

Cytomegalovirus Infection Impairs the Mobilization of Tissue-Resident Innate Lymphoid Cells into the Peripheral Blood Compartment in Response to Acute Exercise

Circulating immune cell numbers and phenotypes are impacted by high-intensity acute bouts of exercise and infection history with the latent herpesviruses cytomegalovirus (CMV). In particular, CMV infection history impairs the exercise-induced mobilization of cytotoxic innate lymphoid cells 1 (ILC1) cells, also known as NK cells, in the blood. However, it remains unknown whether exercise and CMV infection modulate the mobilization of traditionally tissue-resident non-cytotoxic ILCs into the peripheral blood compartment. To address this question, 22 healthy individuals with or without CMV (20–35 years—45% CMVpos) completed 30 min of cycling at 70% VO2 max, and detailed phenotypic analysis of circulating ILCs was performed at rest and immediately post-exercise. We show for the first time that a bout of high-intensity exercise is associated with an influx of ILCs that are traditionally regarded as tissue-resident. In addition, this is the first study to highlight that latent CMV infection blunts the exercise-response of total ILCs and progenitor ILCs (ILCPs). These promising data suggest that acute exercise facilitates the circulation of certain ILC subsets, further advocating for the improvements in health seen with exercise by enhancing cellular mobilization and immunosurveillance, while also highlighting the indirect deleterious effects of CMV infection in healthy adults.

Profiling the Blood Compartment of Hematopoietic Stem Cell Transplant Patients During Human Cytomegalovirus Reactivation

Human cytomegalovirus (HCMV) is a widespread pathogen establishing a latent infection in its host. HCMV reactivation is a major health burden in immunocompromised individuals, and is a major cause of morbidity and mortality following hematopoietic stem cell transplantation (HSCT). Here we determined HCMV genomic levels using droplet digital PCR in different peripheral blood mononuclear cell (PBMC) populations in HCMV reactivating HSCT patients. This high sensitivity approach revealed that all PBMC populations harbored extremely low levels of viral DNA at the peak of HCMV DNAemia. Transcriptomic analysis of PBMCs from high-DNAemia samples revealed elevated expression of genes typical of HCMV specific T cells, while regulatory T cell enhancers as well as additional genes related to immune response were downregulated. Viral transcript levels in these samples were extremely low, but remarkably, the detected transcripts were mainly immediate early viral genes. Overall, our data indicate that HCMV DNAemia is associated with distinct signatures of immune response in the blood compartment, however it is not necessarily accompanied by substantial infection of PBMCs and the residual infected PBMCs are not productively infected.

COVID-19 is, in the end, an endothelial disease

The vascular endothelium provides the crucial interface between the blood compartment and tissues, and displays a series of remarkable properties that normally maintain homeostasis. This tightly regulated palette of functions includes control of haemostasis, fibrinolysis, vasomotion, inflammation, oxidative stress, vascular permeability, and structure. While these functions participate in the moment-to-moment regulation of the circulation and coordinate many host defence mechanisms, they can also contribute to disease when their usually homeostatic and defensive functions over-reach and turn against the host. SARS-CoV-2, the aetiological agent of COVID-19, causes the current pandemic. It produces protean manifestations ranging from head to toe, wreaking seemingly indiscriminate havoc on multiple organ systems including the lungs, heart, brain, kidney, and vasculature. This essay explores the hypothesis that COVID-19, particularly in the later complicated stages, represents an endothelial disease. Cytokines, protein pro-inflammatory mediators, serve as key danger signals that shift endothelial functions from the homeostatic into the defensive mode. The endgame of COVID-19 usually involves a cytokine storm, a phlogistic phenomenon fed by well-understood positive feedback loops that govern cytokine production and overwhelm counter-regulatory mechanisms. The concept of COVID-19 as an endothelial disease provides a unifying pathophysiological picture of this raging infection, and also provides a framework for a rational treatment strategy at a time when we possess an indeed modest evidence base to guide our therapeutic attempts to confront this novel pandemic.

Dissecting the common and compartment-specific features of COVID-19 severity in the lung and periphery with single-cell resolution

ABSTRACTAs the global COVID-19 pandemic continues to escalate, no effective treatment has yet been developed for the severe respiratory complications of this disease. This may be due in large part to the unclear immunopathological basis for the development of immune dysregulation and acute respiratory distress syndrome (ARDS) in severe and critical patients. Specifically, it remains unknown whether the immunological features of the disease that have been identified so far are compartment-specific responses or general features of COVID-19. Additionally, readily detectable biological markers correlated with strata of disease severity that could be used to triage patients and inform treatment options have not yet been identified. Here, we leveraged publicly available single-cell RNA sequencing data to elucidate the common and compartment-specific immunological features of clinically severe COVID-19. We identified a number of transcriptional programs that are altered across the spectrum of disease severity, few of which are common between the lung and peripheral immune environments. In the lung, comparing severe and moderate patients revealed severity-specific responses of enhanced interferon, A20/IκB, IL-2, and IL-6 pathway signatures along with broad signaling activity of IFNG, SPP1, CCL3, CCL8, and IL18 across cell types. These signatures contrasted with features unique to ARDS observed in the blood compartment, which included depletion of interferon and A20/IκB signatures and a lack of IL-6 response. The cell surface marker S1PR1 was strongly upregulated in patients diagnosed with ARDS compared to non-ARDS patients in γδ T cells of the blood compartment, and we nominate S1PR1 as a potential marker for immunophenotyping ARDS in COVID-19 patients using flow cytometry.HIGHLIGHTSCOVID-19 disease severity is associated with a number of compositional shifts in the cellular makeup of the blood and lung environments.Transcriptional data suggest differentially expressed cell surface proteins as markers for COVID-19 immunophenotyping from BALF and PBMC samples.Severity-specific features COVID-19 manifest at the pathway level, suggesting distinct changes to epithelia and differences between local and systemic immune dynamics.Immune-epithelial cellular communication analysis identifies ligands implicated in transcriptional regulation of proto-oncogenes in the lung epithelia of severe COVID-19 patients.Network analysis suggests broadly-acting dysregulatory ligands in the pulmonary microenvironment as candidate therapeutic targets for the treatment of severe COVID-19.

P1108FLUID DYNAMIC ASSESSMENT OF THERANOVA DIALYZER THROUGH CT IMAGING TECHNIQUE

Background and Aims Inadequate removal of molecules between 5and50KDa, due to their restriction in diffusibility, may cause long-term complication in chronic hemodialysis patients. Medium Cut-off(MCO) is a new class of membranes with enhanced sieving properties and negligible albumin loss, thanks to its high molecular weight(MW) retention onset and MW cut-off value lower than albumin MW. MCO membrane used in HD allows to perform expanded hemodialysis (HDx), a technique based on high internal filtration(IF). Our previous study quantified the IF of Theranova dialyzer leveraging a nuclear imaging technique. In order to characterize the local distribution of the IF, an in vitro study assessing the fluid dynamics inside Theranova dialyzer was conducted through CT imaging technique. Method Dialyzers Theranova 400 and 500(Baxter, Deerfield, USA) were placed in vertical position in the CT gantry. Blood and dialysate were circulated in countercurrent at 300ml/min and 500 ml/min, respectively. The two compartments were analyzed separately, injecting the dye solution, for both filters. Longitudinal sections, 0.5cm thick, were recorded for 60seconds. Results In blood compartment, dye solution immediately after its entrance in the dialyzer demonstrates homogeneous progression, while different velocity profiles were observed among the fibers proceeding to the outlet port (Fig b). In dialysate compartment, dye solution is distributed in the periphery first (Fig d), then seeps in the fibers bundle and reaches the complete compartment filling. Conclusion The homogeneous dye profile immediately after its entrance in blood compartment demonstrated a good design of the inlet port; the optimal dye distribution reached in both blood and dialysate compartments ensure that IF phenomenon is equally achieved in both central and peripheral regions of the dialyzer.

A Unique Gene-Silencing Approach, Using an Intelligent RNA Expression Device (iRed), Results in Minimal Immune Stimulation When Given by Local Intrapleural Injection in Malignant Pleural Mesothelioma

Background: We have recently introduced an intelligent RNA expression device (iRed), comprising the minimum essential components needed to transcribe short hairpin RNA (shRNA) in cells. Use of iRed efficiently produced shRNA molecules after transfection into cells and alleviated the innate immune stimulation following intravenous injection. Methods: To study the usefulness of iRed for local injection, the engineered iRed encoding luciferase shRNA (Luc iRed), complexed with cationic liposomes (Luc iRed/liposome-complexes), was intrapleurally injected into an orthotopic mesothelioma mouse model. Results: Luc iRed/liposome-complexes markedly suppressed the expression of a luciferase marker gene in pleurally disseminated mesothelioma cells. The suppressive efficiency was correlated with the expression level of shRNA within the mesothelioma cells. In addition, intrapleural injection of iRed/liposome-complexes did not induce IL-6 production in the pleural space and consequently in the blood compartment, although plasmid DNA (pDNA) or dsDNA (the natural construct for iRed) in the formulation did. Conclusion: Local delivery of iRed could augment the in vivo gene silencing effect without eliciting pronounced innate immune stimulation. Our results might hold promise for widespread utilization of iRed as an RNAi-based therapeutic for intracelial malignant cancers.

Analysis of Endotoxin Adsorption in Two Swedish Patients with Septic Shock

Background: Lipopolysaccharide (endotoxin) from the outer Gram-negative bacterial wall can induce a harmful immunologic response, involving hemodynamic deprivation, and is one important motor driving the septic cascade. The positively charged poly-imine ethylene layer on the oXiris membrane is capable of adsorbing negatively charged endotoxin molecules and removing them from the blood compartment. Endotoxin is detrimental and should be removed from blood. Summary: The adsorbable endotoxin fraction in blood arises from a tight balance between seeding from an infectious focus and removal by an overwhelmed immune system. The net sum of remaining endotoxin in blood is available for an adsorption process in the oXiris filter. Endotoxin data from 2 patients with severe Gram-negative septic shock and endotoxemia in this case series, speaks for a considerable share of the adsorption of the oXiris filter in the endotoxin net removal over time. Key Messages: Analysis of combined in vitro and in vivo data speaks for an effect of the oXiris filter in lowering endotoxin.

On the Origins of the Cerebral IVIM Signal

PurposeIntravoxel incoherent motion (IVIM) has been proposed as a means of non-invasive MRI measurement of perfusion parameters such as blood flow and blood volume. Its main competitor in the brain is arterial spin labelling (ASL). In theory, IVIM should not suffer from some of the same limitations as ASL such as poor signal in white matter, and assumptions about arterial arrival times that may be violated in the presence of pathology.MethodsIn this study we aimed to test IVIM as a viable alternative to ASL for quantitative imaging of perfusion parameters in the brain. First, a direct comparison was performed between IVIM and multi-post label delay pseudo-continuous ASL; second, IVIM images were acquired with and without nulling cerebrospinal fluid; and finally, ultra-high resolution IVIM was performed to minimise partial voluming.ResultsIn all three tests, IVIM failed to disprove the null hypothesis, strongly suggesting that, at least within the brain, the technique does not measure perfusion parameters as proposed.ConclusionFurthermore, the results obtained suggest that the contrast visible in IVIM-derived images is primarily sensitive to cerebrospinal fluid, and not the microvascular blood compartment.