Open chest and pericardium facilitate transpulmonary passage of venous air emboli

Background: Transpulmonary passage of air emboli can lead to fatal brain- and myocardial infarctions. We studied whether pigs with open chest and pericardium had a greater transpulmonary passage of venous air emboli than pigs with closed thorax. Methods: We allocated pigs with verified closed foramen ovale to venous air infusion with either open chest with sternotomy and opening of the pleura and pericardium (n = 8) or closed thorax (n = 16). All pigs received a five-hour intravenous infusion of ambient air, starting at 4-6 mL/kg/h and increased by 2 mL/kg/h each hour. We assessed transpulmonary air passage by transesophageal M-mode echocardiography and present the results as median with inter-quartile range (IQR). Results: Transpulmonary air passage occurred in all pigs with open chest and pericardium and in nine pigs with closed thorax (56%). Compared to pigs with closed thorax, pigs with open chest and pericardium had a shorter to air passage (10 minutes (5-16) vs. 120 minutes (44-212), P < .0001), a smaller volume of infused air at the time of transpulmonary passage (12 mL (10-23) vs.170 mL (107-494), P < .0001), shorter time to death (122 minutes (48-185) vs 263 minutes (248-300, P = .0005) and a smaller volume of infused air at the time of death (264 mL (53-466) vs 727 mL (564-968), P = .001). In pigs with open chest and, infused air and time to death correlated strongly (r = 0.95, P = .001). Conclusion: Open chest and pericardium facilitated the transpulmonary passage of intravenously infused air in pigs

Complement activation is associated with poor outcome after out-of-hospital cardiac arrest

Background - Cardiopulmonary resuscitation after cardiac arrest initiates a whole-body ischemia-reperfusion injury, which may activate the innate immune system, including the complement system. We hypothesized that complement activation and subsequent release of soluble endothelial activation markers were associated with cerebral outcome including death. Methods - Outcome was assessed at six months and defined by cerebral performance category scale (1−2; good outcome, 3−5; poor outcome including death) in 232 resuscitated out-of-hospital cardiac arrest patients. Plasma samples obtained at admission and day three were analysed for complement activation products C3bc, the soluble terminal complement complex (sC5b-9), and soluble CD14. Endothelial cell activation was measured by soluble markers syndecan-1, sE-selectin, thrombomodulin, and vascular cell adhesion molecule. Results - Forty-nine percent of the patients had good outcome. C3bc and sC5b-9 were significantly higher at admission compared to day three (p Conclusion - Complement system activation, reflected by sC5b-9 at admission, leading to subsequent endothelial cell activation, was associated with poor outcome in out-of-hospital cardiac arrest patients

Systemic complement activation is associated with respiratory failure in COVID-19 hospitalized patients

The new SARS-CoV-2 pandemic leads to COVID-19 with respiratory failure, substantial morbidity, and significant mortality. Overactivation of the innate immune response is postulated to trigger this detrimental process. The complement system is a key player in innate immunity. Despite a few reports of local complement activation, there is a lack of evidence that the degree of systemic complement activation occurs early in COVID-19 patients, and whether this is associated with respiratory failure. This study shows that a number of complement activation products are systemically, consistently, and long-lastingly increased from admission and during the hospital stay. Notably, the terminal sC5b-9 complement complex was associated with respiratory failure. Thus, complement inhibition is an attractive therapeutic approach for treatment of COVD-19

The function of the complement system remains fully intact throughout the course of allogeneic stem cell transplantation

IntroductionHematopoietic stem cell transplantation (HSCT) is associated with immune complications and endothelial dysfunction due to intricate donor-recipient interactions, conditioning regimens, and inflammatory responses.MethodsThis study investigated the role of the complement system during HSCT and its interaction with the cytokine network. Seventeen acute myeloid leukemia patients undergoing HSCT were monitored, including blood sampling from the start of the conditioning regimen until four weeks post-transplant. Clinical follow-up was 200 days.ResultsTotal complement functional activity was measured by WIELISA and the degree of complement activation by ELISA measurement of sC5b-9. Cytokine release was measured using a 27-multiplex immuno-assay. At all time-points during HSCT complement functional activity remained comparable to healthy controls. Complement activation was continuously stable except for two patients demonstrating increased activation, consistent with severe endotheliopathy and infections. In vitro experiments with post-HSCT whole blood challenged with Escherichia coli, revealed a hyperinflammatory cytokine response with increased TNF, IL-1β, IL-6 and IL-8 formation. Complement C3 inhibition markedly reduced the cytokine response induced by Staphylococcus aureus, Aspergillus fumigatus, and cholesterol crystals.DiscussionIn conclusion, HSCT patients generally retained a fully functional complement system, whereas activation occurred in patients with severe complications. The complement-cytokine interaction indicates the potential for new complement-targeting therapeutic strategies in HSCT

The fibrosis progression, and treatment of the NCU-G1gt/gt mouse model

Hepatic fibrogenesis is a wound healing response to continuous or chronic insults to the liver. The fibrotic stimuli are often based on disease, genetic disorders, abuse of alcohol and drugs or physical injury to the liver. The stimuli activate hepatic stellate cells (HSC) and other fibrogenic cell types, which induce up-regulation of the expression of pro-fibrotic factors and extracellular matrix (ECM) components leading to an alternated ECM. The matrix metalloproteinases (MMPs) and their inhibitors tissue inhibitors of metalloproteinases (TIMPs) are the main ECM remodelers, and an imbalance in their expression may lead to fibrosis. If left untreated, it may develop to its severe form, cirrhosis. Liver fibrosis is a dynamic process that can be reversed both spontaneously, by removal of the causative agent, and therapeutically by the aid of anti-fibrotic drugs. NCU-G1 (kidney predominant protein) is a protein consisting of 404 amino acids, in mice, with a predicted molecular weight of 43.8 kDa. It is highly conserved among species. Ncug1 is highly expressed in liver, kidney and prostate. NCU-G1 has been shown to be a nuclear protein functioning as a co-activator for peroxisome proliferator activated receptor α (PPAR-α), and a higly glycosylated lysosomal membrane protein. A NCU-G1gt/gt mouse has been developed, and it is shown to successfully lack the expression of Ncug1. The NCU-G1 gt/gt mice are fertile and grow normally, but spontaneously develop liver fibrosis. This study investigates the fibrosis progression in the NCU-G1 gt/gt mice with gene expression, protein and liver component analyses. A pilot study was conducted to investigate the applicability of the NCU-G1 gt/gt mice as a fibrosis model organism, with treatment with the anti-fibrotic agent sodium hydrogen sulfide (NaHS). The fibrosis in the NCU-G1 gt/gt mice liver increase until the mice reaches 4.5 months of age, after 4.5 months the fibrotic state revert to some degree. Treatment with NaHS attenuated the fibrotic state to some degree in the NCU-G1 gt/gt mice

Complement Activation in 22q11.2 Deletion Syndrome

The 22q11.2 deletion syndrome (22q11.2 del), also known as DiGeorge syndrome, is a genetic disorder with an estimated incidence of 1:3000 to 1:6000 births. These patients may suffer from affection of many organ systems with cardiac malformations, immunodeficiency, hypoparathyroidism, autoimmunity, palate anomalies, and psychiatric disorders being the most frequent. The importance of the complement system in 22q11.2 del has not been investigated. The objective of this study was to evaluate the complement system in relation to clinical and immunological parameters in patients. A national cohort of patients (n = 69) with a proven heterozygous deletion of chromosome 22q11.2 and a group of age and sex matched controls (n = 56) were studied. Functional capacity of the classical, lectin, and alternative pathways of the complement system as well as complement activation products C3bc and terminal complement complex (TCC) were accessed and correlated to clinical features. All patients in our study had normal complement activation in both classical and alternative pathways. The frequency of mannose-binding lectin deficiency was comparable to the normal population. The patients had significantly raised plasma levels of C3bc and a slight, but not significant, increase in TCC compared with controls. This increase was associated with the presence of psychiatric disorders in patients. The present study shows no complement deficiencies in 22q11.2 deletion syndrome. On the contrary, there are signs of increased complement activation in these patients. Complement activation is particularly associated with the presence of psychiatric disorders

Lack of the lysosomal membrane protein, GLMP, in mice results in metabolic dysregulation in liver

Ablation of glycosylated lysosomal membrane protein (GLMP, formerly known as NCU-G1) has been shown to cause chronic liver injury which progresses into liver fibrosis in mice. Both lysosomal dysfunction and chronic liver injury can cause metabolic dysregulation. Glmpgt/gt mice (formerly known as Ncu-g1gt/gtmice) were studied between 3 weeks and 9 months of age. Body weight gain and feed efficiency of Glmpgt/gt mice were comparable to wild type siblings, only at the age of 9 months the Glmpgt/gt siblings had significantly reduced body weight. Reduced size of epididymal fat pads was accompanied by hepatosplenomegaly in Glmpgt/gt mice. Blood analysis revealed reduced levels of blood glucose, circulating triacylglycerol and non-esterified fatty acids in Glmpgt/gt mice. Increased flux of glucose, increased de novo lipogenesis and lipid accumulation were detected in Glmpgt/gt primary hepatocytes, as well as elevated triacylglycerol levels in Glmpgt/gt liver homogenates, compared to hepatocytes and liver from wild type mice. Gene expression analysis showed an increased expression of genes involved in fatty acid uptake and lipogenesis in Glmpgt/gt liver compared to wild type. Our findings are in agreement with the metabolic alterations observed in other mouse models lacking lysosomal proteins, and with alterations characteristic for advanced chronic liver injury

Ficolins do not alter host immune responses to lipopolysaccharide-induced inflammation in vivo

Ficolins are a family of pattern recognition molecules that are capable of activating the lectin pathway of complement. A limited number of reports have demonstrated a protective role of ficolins in animal models of infection. In addition, an immune modulatory role of ficolins has been suggested. Yet, the contribution of ficolins to inflammatory disease processes remains elusive. To address this, we investigated ficolin deficient mice during a lipopolysaccharide (LPS)-induced model of systemic inflammation. Although murine serum ficolin was shown to bind LPS in vitro, there was no difference between wildtype and ficolin deficient mice in morbidity and mortality by LPS-induced inflammation. Moreover, there was no difference between wildtype and ficolin deficient mice in the inflammatory cytokine profiles after LPS challenge. These findings were substantiated by microarray analysis revealing an unaltered spleen transcriptome profile in ficolin deficient mice compared to wildtype mice. Collectively, results from this study demonstrate that ficolins are not involved in host response to LPS-induced systemic inflammation

Complement Activation in 22q11.2 Deletion Syndrome

Abstract The 22q11.2 deletion syndrome (22q11.2 del), also known as DiGeorge syndrome, is a genetic disorder with an estimated incidence of 1:3000 to 1:6000 births. These patients may suffer from affection of many organ systems with cardiac malformations, immunodeficiency, hypoparathyroidism, autoimmunity, palate anomalies, and psychiatric disorders being the most frequent. The importance of the complement system in 22q11.2 del has not been investigated. The objective of this study was to evaluate the complement system in relation to clinical and immunological parameters in patients. A national cohort of patients ( n  = 69) with a proven heterozygous deletion of chromosome 22q11.2 and a group of age and sex matched controls ( n  = 56) were studied. Functional capacity of the classical, lectin, and alternative pathways of the complement system as well as complement activation products C3bc and terminal complement complex (TCC) were accessed and correlated to clinical features. All patients in our study had normal complement activation in both classical and alternative pathways. The frequency of mannose-binding lectin deficiency was comparable to the normal population. The patients had significantly raised plasma levels of C3bc and a slight, but not significant, increase in TCC compared with controls. This increase was associated with the presence of psychiatric disorders in patients. The present study shows no complement deficiencies in 22q11.2 deletion syndrome. On the contrary, there are signs of increased complement activation in these patients. Complement activation is particularly associated with the presence of psychiatric disorders

Age-dependent development of liver fibrosis in Glmp gt/gt mice

Background Mice lacking glycosylated lysosomal membrane protein (Glmp gt/gt mice) have liver fibrosis as the predominant phenotype due to chronic liver injury. The Glmp gt/gt mice grow and reproduce at the same rate as their wild-type siblings. Life expectancy is around 18 months. Methods Wild-type and Glmp gt/gt mice were studied between 1 week and 18 months of age. Livers were analyzed using histological, immunohistochemical, biochemical, and qPCR analyses. Results It was shown that Glmp gt/gt mice were not born with liver injury; however, it appeared shortly after birth as indicated by excess collagen expression, deposition of fibrous collagen in the periportal areas, and increased levels of hydroxyproline in Glmp gt/gt liver. Liver functional tests indicated a chronic, mild liver injury. Markers of inflammation, fibrosis, apoptosis, and modulation of extracellular matrix increased from an early age, peaking around 4 months of age and followed by attenuation of these signals. To compensate for loss of hepatocytes, the oval cell compartment was activated, with the highest activity of the oval cells detected at 3 months of age, suggesting insufficient hepatocyte proliferation in Glmp gt/gt mice around this age. Although constant proliferation of hepatocytes and oval cells maintained adequate hepatic function in Glmp gt/gt mice, it also resulted in a higher frequency of liver tumors in older animals. Conclusions The Glmp gt/gt mouse is proposed as a model for slowly progressing liver fibrosis and possibly as a model for a yet undescribed human lysosomal disorder