Plasma thioredoxin levels during post-cardiac arrest syndrome: relationship with severity and outcome.

INTRODUCTION: Despite experimental evidence, clinical demonstration of acute state of oxidative stress and inflammation during post-cardiac arrest syndrome is lacking. Plasma level of thioredoxin (TRX), a redox-active protein induced under conditions of oxidative stress and inflammation, is increased in various critical care conditions. We determined plasma TRX concentrations after cardiac arrest and assessed relationships with severity and outcome. METHODS: Retrospective study of consecutive patients admitted to a single academic intensive care unit (ICU) for out-of-hospital cardiac arrest (between July 2006 and March 2008). Plasma levels of TRX were measured at admission, day (D) 1, 2 and 3. RESULTS: Of 176 patients included, median TRX values measured in ICU survivors and non-survivors were, respectively: 22 ng/mL (7.8 to 77) vs. 72.4 (21.9 to 117.9) at admission (P < 0.001); 5.9 (3.5 to 25.5) vs. 23.2 (5.8 to 81.4) at D1 (P = 0.003); 10.8 (3.6 to 50.8) vs. 11.7 (4.5 to 66.4) at D2 (P = 0.22); and 16.7 (5.3 to 68.3) vs. 17 (4.3 to 62.9) at D3 (P = 0.96). Patients dying within 24 hours had significantly (P < 0.001) higher TRX levels (118.6 ng/mL (94.8 to 280)) than those who died after 24 hours or survived (50.8 (13.9 to 95.7) and 22 (7.8 to 77)). The area under the ROC curve to predict early death was 0.84 (0.76 to 0.91). CONCLUSIONS: Our data show for the first time that TRX levels were elevated early following cardiac arrest, suggestive of oxidative stress and inflammation occurring with this condition. Highest values were found in the most severe patients. TRX could be a useful tool for further exploration and comprehension of post-cardiac arrest syndrome.

Association between preoperative plasma sRAGE levels and recovery from cardiac surgery.

BACKGROUND: The receptor for advanced glycation end products (RAGE) is an inflammation-perpetuating receptor, and soluble RAGE (sRAGE) is a marker of cellular RAGE expression. This study investigated whether raised plasma levels prior to surgery of sRAGE or S100A8/A9 (a RAGE ligand) were associated with longer duration of hospital care in patients undergoing cardiac surgery necessitating cardiopulmonary bypass. METHODS: Patients (n = 130) undergoing elective cardiac surgery were enrolled prospectively. Plasma sRAGE and S100A8/A9 concentrations were measured before and 2 h after surgery. RESULTS: Preoperative plasma sRAGE increased significantly (P < 0.0001) from 1.06 ng/mL (IQR, 0.72-1.76) to 1.93 ng/mL (IQR, 1.14-2.63) 2 h postoperatively. Plasma S100A8/9 was also significantly (P < 0.0001) higher 2 h postoperatively (2.37 µ g/mL, IQR, 1.81-3.05) compared to pre-operative levels (0.41 µ g/mL, IQR, 0.2-0.65). Preoperative sRAGE, but not S100A8/A9, was positively and significantly correlated with duration of critical illness (r = 0.3, P = 0.0007) and length of hospital stay (LOS; r = 0.31, P < 0.0005). Multivariate binary logistic regression showed preoperative sRAGE to be, statistically, an independent predictor of greater than median duration of critical illness (odds ratio 16.6, P = 0.014) and to be, statistically, the strongest independent predictor of hospital LOS. CONCLUSION: Higher preoperative plasma sRAGE levels were associated with prolonged duration of care in adults undergoing cardiac surgery requiring cardiopulmonary bypass.

Lest we forget the endothelial glycocalyx in sepsis.

Sepsis is the third largest cause of death in industrialised countries, but treatment remains largely supportive and effective therapeutic interventions are urgently needed. Disruption and dysfunction of the microvascular endothelium leading directly or indirectly to multiple organ failure are now recognised to underpin the pathophysiology of sepsis. Biomarkers of endothelial activation may therefore assume an important role in guiding future research efforts. We suggest that integral to this approach is the investigation and evaluation of endothelial glycocalyx biomarkers, not only as indicators of the pathogenic process but also to inform the development of pharmacological and other therapies.

Human pulmonary artery endothelial cells upregulate ACE2 expression in response to iron-regulatory elements: Potential implications for SARS-CoV-2 infection.

Vascular endothelial cell dysfunction is reported in severe coronavirus disease 2019 disease, however, controversy exists regarding levels of angiotensin-converting enzyme 2 (ACE2) expression, a coreceptor for severe acute respiratory syndrome coronavirus 2, in these cells. We report ACE2 expression and positive regulation by both interleuki-6, hepcidin, and ferroportin knock-down in pulmonary artery endothelial cells with potential implications for viral infection.

Plasma S100A8/A9 heterodimer is an early prognostic marker of acute kidney injury associated with cardiac surgery.

AIM: We investigated whether plasma levels of the inflammation marker S100A8/A9, could predict acute kidney injury (AKI) onset in patients undergoing cardiac surgery necessitating cardiopulmonary bypass (CPB). PATIENTS & METHODS: Plasma levels of S100A8/A9 and other neutrophil cytosolic proteins were measured in 39 patients pre- and immediately post-CPB. RESULTS: All markers increased significantly post-CPB with S100A8/A9, S100A12 and myeloperoxidase levels significantly higher in patients who developed AKI within 7 days. S100A8/A9 had good prognostic utility for AKI, with an area under the receiver operating characteristic curve of 0.81 (95% CI: 0.676-0.949) and a cut-off value of 10.6 µg/ml (85.7% sensitivity and 75% specificity) irrespective of age. CONCLUSION: Plasma S100A8/A9 levels immediately after cardiac surgery, can predict onset of AKI, irrespective of age.

The value of mobile tablet computers (iPads) in the undergraduate medical curriculum.

The deployment of mobile tablet computers in medical teaching and learning is viewed with mounting interest. Medical educators are embracing insights from technological advancements to ensure that students are equipped with the necessary tools to flourish as physicians. Here, we reflect on the benefits and challenges of the tablet learning experience within undergraduate medicine and how students may make the best use of it.

Drug-Coated Balloon-Only Percutaneous Coronary Intervention for the Treatment of De Novo Coronary Artery Disease: A Systematic Review.

Percutaneous coronary intervention (PCI) with a drug coated balloon (DCB) is a novel treatment which seeks to acutely dilate a coronary stenosis and deliver an anti-proliferative drug to the vessel wall (reducing the risk of re-stenosis), without implanting a drug eluting stent (DES). In this study, we performed a systematic review of stentless DCB-only angioplasty in de novo coronary artery disease. We identified 41 studies examining the effects of DCB-only PCI in a variety of clinical scenarios including small vessels, bifurcations, calcified lesions, and primary PCI. DCB-only PCI appears to be associated with comparable clinical outcomes to DESs and superior angiographic outcomes to plain-old balloon angioplasty. Although current data are promising, there is still a need for further long-term randomized control trial data comparing a DCB-only approach specifically against a second- or third-generation DES. A 4-week period of dual antiplatelet therapy provides a real advantage for the DCB-only PCI approach, which is not possible with most DESs. Since rates of adverse clinical outcomes are very low for all PCI procedures attention should be turned to the development of robust endpoints with which to compare DCB-only PCI approaches to the standard treatment with a DES.

Drug-eluting balloons with provisional bail-out or adjunctive stenting in de novo coronary artery lesions-a systematic review and meta-analysis.

BACKGROUND: Efficacy of drug-eluting balloons (DEB) for treatment of de novo coronary lesions remains controversial. The present systematic review and meta-analysis of randomised controlled trials assessed DEB with bare-metal stents (BMS) and also DEB with provisional bail-out stents ('DEB-only' strategy), to other conventional options: plain-old balloon angioplasty (POBA), BMS and drug-eluting stents (DES). METHODS: A systematic literature search from January 2000 until May 2017 was conducted. Primary outcome measure, late lumen loss (LLL); and secondary outcomes; binary restenosis, major adverse cardiac events (MACE), target lesion revascularization (TLR), myocardial infarction (MI), cardiovascular death and stent thrombosis were analysed. RESULTS: Seventeen RCTs were included with 2,616 patients. Several comparative groups showed significant differences. DEB with BMS were inferior to DES for LLL [mean difference (MD) =0.12 mm; 95% confidence interval (CI), 0.03 to 0.22; P=0.01]; and binary restenosis [risk ratio (RR) =1.89; (CI, 1.13 to 3.18); P=0.02]. DEB with BMS was superior to BMS for LLL [MD =-0.27 mm; (-0.45 to -0.10); P=0.002]; and MACE [RR =0.64; (0.46 to 0.90); P=0.010]. Finally, DEB alone was superior to POBA for LLL [MD =-0.39 mm; (-0.67 to -0.11); P=0.006] and binary restenosis [RR =0.20; (0.05 to 0.85); P=0.03] in bifurcation lesions. CONCLUSIONS: The results of this meta-analysis showed that whilst DEB with BMS is superior to BMS alone, the combination is inferior to DES for treatment of de novo coronary lesions. Thus, DEB + BMS should not be applied in de novo lesions unless in patients who have absolute contraindications to DES. DEB alone, however, should be considered for relative contraindications to DES such as small vessel disease and bifurcation lesions.

Butanol-extracted lipoteichoic acid induces in vivo leukocyte adhesion.

Lipoteichoic acid (LTA), an immunostimulatory component of the cell walls of gram positive bacteria, has pro-inflammatory effects in vitro and in vivo. However, one in vivo study concluded that LTA had no noticeable effects on leukocyte recruitment. In this study we investigated the effects of highly purified LTA, prepared by butanol extraction (Bu-LTA) at room temperature, on in vivo leukocyte adhesion. Using intravital microscopy we measured adhesion of leukocytes in mesenteric post-capillary venules of rats and mice. Topical superfusion of Bu-LTA (1 microg/ml) in rats significantly (p<0.05) increased adhesion within 30 min. By contrast, hot phenol-extracted LTA did not increase adhesion. Alkaline hydrolysis of Bu-LTA removed alanine residues and prevented adhesion. Also, pre-administration of anti-rat beta2-integrin antibody abolished Bu-LTA-induced adhesion. Finally, intraperitoneal injection of Bu-LTA (100 microg/ml) into mice also significantly (p<0.01) increased leukocyte adhesion measured at 60 min. In conclusion, Bu-LTA with intact alanine residues promotes beta2-integrin-dependent leukocyte adhesion in vivo.

Persistently low plasma thioredoxin is associated with meningococcal septic shock in children.

OBJECTIVE: To compare plasma levels of thioredoxin (Trx), TNF-alpha and IL-1 beta in children during the acute phase of meningococcal septic shock (MSS) and in convalescence. DESIGN AND SETTING: Retrospective, observational study in the paediatric intensive care unit of a postgraduate teaching hospital. PATIENTS: Thirty-five children requiring intensive care for meningococcal sepsis; paired convalescent samples from 30 survivors (median interval between samples 62 days); 25 healthy control children. MEASUREMENTS AND RESULTS: Plasma Trx levels were significantly lower in the children with MSS, both during the acute illness (5.5 ng/ml, IQR 1.4-11.4) and in convalescence (2.5 ng/ml, IQR 0.4-6.9) than controls (18.8 ng/ml, IQR 7.9-25.0). Levels of IL-1 beta and TNF-alpha were higher in patients with acute MSS (30.3 pg/ml, IQR 3.6-63.6, and 145.9 pg/ml, IQR 31.8-278.1 respectively) than controls (3.7 pg/ml, IQR 0-36.9, and 23.8 pg/ml, IQR 0-124.3, respectively). Levels fell in convalescence (3.7 pg/ml, IQR 0-25.5, 3.7 pg/ml, IQR 0-304.8, respectively). Plasma Trx was higher in non-survivors, albeit a small group (n=5), than in survivors (n=30). Trx, IL-1 beta, and TNF-alpha levels were not correlated with predicted mortality as assessed by the paediatric risk of mortality (PRISM) score. CONCLUSIONS: Children with MSS exhibit persistently low plasma levels of Trx during acute illness and in convalescence.

Thioredoxin: friend or foe in human disease?

Thioredoxin (Trx), a small, ubiquitous thiol [sulfydryl (-SH)] protein, is one of the most important regulators of reduction-oxidation (redox) balance and, thus, redox-controlled cell functions. Although Trx was discovered 40 years ago in bacteria, the number and diversity of processes that Trx influences in human cells have only been appreciated recently. Processes influenced by Trx include the control of cellular redox balance, the promotion of cell growth, the inhibition of apoptosis and the modulation of inflammation. Not surprisingly, the role of Trx in a wide range of human diseases and conditions, including cancer, viral disease, ischaemia-reperfusion injury, cardiac conditions, aging, premature birth and newborn physiology, is subject to intense investigation. However, whether Trx contributes to or prevents the pathology of a particular condition is not always clear. In this article, we review the role of Trx in human disease and relate this to its redox activity and biological properties, and discuss the development and use of therapies that either inhibit or augment Trx activity.

Regulation of chemokine expression in atherosclerosis.

(1) Chemokines play a central role in the pathogenesis of atherosclerosis, contributing to leukocyte recruitment, angiogenesis and also proliferation and migration of smooth muscle cells into atherosclerotic plaques. (2) Leukocytes and endothelial cells are an important source of chemokines, and many of the risk factors associated with atherosclerosis increase chemokine expression. There is now a body of evidence to suggest that interactions between cells such as leukocytes and endothelial cells amplify chemokine release, and this may contribute to sustained chemokine generation in inflammatory conditions. (3) This article summarises, briefly, what is currently known about chemokines release. A number of important pharmacological strategies used in the treatment of atherosclerosis inhibit chemokine release and the extent to which this may contribute to their therapeutic effect will be discussed. Understanding the mechanisms controlling chemokine expression is essential for the design of specific therapeutic interventions in atherosclerosis.

Raised plasma Robo4 and cardiac surgery-associated acute kidney injury.

OBJECTIVE: Endothelial dysfunction associated with systemic inflammation can contribute to organ injury/failure following cardiac surgery requiring cardiopulmonary bypass (CPB). Roundabout protein 4 (Robo4), an endothelial-expressed transmembrane receptor and regulator of cell activation, is an important inhibitor of endothelial hyper-permeability. We investigated the hypothesis that plasma levels of Robo4 are indicative of organ injury, in particular acute kidney injury (AKI), after cardiac surgery. METHODS: Patients (n = 32) undergoing elective cardiac surgery with CPB were enrolled, prospectively. Plasma Robo4 concentrations were measured pre-, 2 and 24 h post-operatively, using a commercially available ELISA. Plasma and endothelial markers of inflammation [interleukin (IL) -6, -8, -10: von Willibrand factor (vWF) and angiopoeitin-2 (Ang-2)] and the AKI marker, neutrophil gelatinase-associated lipocalin (NGAL), were also measured by ELISA. RESULTS: Plasma Robo4 increased significantly (p<0.001) from pre-operative levels of 2515 ± 904 pg/ml to 4473 ± 1915 pg/ml, 2 h after surgery; and returned to basal levels (2682 ± 979 pg/ml) by 24 h. Plasma cytokines, vWF and NGAL also increased 2 h post-operatively and remained elevated at 24 h. Ang-2 increased 24 h post-operatively, only. There was a positive, significant correlation (r = 0.385, p = 0.0298) between Robo-4 and IL-10, but not other cytokines, 2 h post-operatively. Whilst raised Robo4 did not correlate with indices of lung dysfunction or other biomarkers of endothelial activation; there was a positive, significant correlation between raised (2 h) plasma NGAL and Robo4 (r = 0.4322, p = 0.0135). When patients were classed as AKI or non-AKI either using NGAL cut-off of 150 ng/ml, or the AKI Network (AKIN) clinical classification; plasma Robo4 was significantly higher (p = 0.0073 and 0.003, respectively) in AKI vs. non-AKI patients (NGAL cut-off: 5350 ± 2191 ng/ml, n = 16 vs. 3595 ± 1068 pg/ml, n = 16; AKIN: 6546 pg/ml, IQR 5025-8079, n = 6; vs. 3727 pg/ml, IQR 1962-3727, n = 26) subjects. CONCLUSION: Plasma Robo4 levels are increased, transiently, following cardiac surgery requiring CPB; and higher levels in patients with AKI suggest a link between endothelial dysregulation and onset of AKI.

Differences in lipopolysaccharide- and lipoteichoic acid-induced cytokine/chemokine expression.

PURPOSE: To investigate differences in cytokine/chemokine release in response to lipoteichoic acid (LTA) or lipopolysaccharide (LPS) and contributing cellular mechanisms, in order to improve understanding of the pathogenesis of sepsis. METHODS: Levels of cytokines/chemokines were measured in plasma and peritoneal lavage fluid of 10-week-old male mice (C57/B16) following intraperitoneal injection of LTA or LPS (250 µg), and in supernatants of murine J774.2 cells, immortalised blood monocytes, or isolated human monocytes treated with LTA or LPS (0-10 µg/ml). The role of cytokine/chemokine messenger RNA (mRNA) stability versus nuclear factor-kappaB (NF-κB) and activator protein-1 (AP-1) in mediating cytokine/chemokine release in J774 cells was also assessed. RESULTS: In mice, plasma levels of keratinocyte-derived chemokine (KC), macrophage inflammatory protein (MIP)-2, interleukin (IL)-10, interferon (IFN)-γ and tumour necrosis factor-alpha (TNF-α) and peritoneal lavage fluid levels of KC, MIP-2 and TNF-α increased significantly 1 h after LPS. Only KC and MIP-2 levels increased 1 h after LTA. LPS-treated (10 µg/ml) J774 cells released MIP-2, IL-10, IFN-γ and TNF-α but not KC (24 h), whereas cells treated with 10 µg/ml LTA released only MIP-2. LPS-stimulated human monocytes released IL-10 and IL-8 (24 h); by contrast, LTA-treated cells released only IL-8. LPS and LTA activated NF-κB and AP-1 in J774 cells. The protein synthesis inhibitor cycloheximide abolished LPS-induced IL-10 mRNA expression and increased LTA- and LPS-induced mRNA for MIP-2 in J774 cells. CONCLUSION: LTA and LPS, at clinically relevant concentrations, induced differential cytokine/chemokine release in vitro and in vivo, via effects distal to activation of NF-κB/AP-1 that might include chromatin remodelling or mRNA stability.

Increased plasma thioredoxin levels in patients with sepsis: positive association with macrophage migration inhibitory factor.

PURPOSE: To establish the relationship between plasma levels of thioredoxin (Trx) and macrophage migration inhibitory factor (MIF) in systemic inflammatory stress syndrome (SIRS)/sepsis. METHODS: Enzyme-linked immunosorbent assay measurements of Trx, MIF, IL-6, -8, and -10 and enzyme-linked fluorescent assay determination of procalcitonin (PCT) in plasma from patients with SIRS/sepsis, neutropenic sepsis, healthy volunteers and pre-oesophagectomy patients. RESULTS: Thioredoxin was significantly higher in SIRS/sepsis patients [101.3 ng ml(-1), interquartile range (IQR) 68.7-155.6, n = 32] compared with that in healthy controls (49.5 ng ml(-1), IQR 31.4-71.1, P < 0.001, n = 17) or pre-oesophagectomy patients (40.5 ng ml(-1), IQR 36.9-63.2, P < 0.01, n = 7), but was not raised in neutropenics (n = 5). MIF levels were also significantly higher in SIRS/sepsis patients (12.1 ng ml(-1), IQR 9.5-15.5, n = 35), but not in the neutropenic group, when compared with healthy controls (9.3 ng ml(-1), IQR 7.3-10.7, P < 0.01, n = 20). Trx levels correlated, positively, with MIF levels and APACHE II scores. Plasma levels of IL-6, -8 and -10 and PCT increased significantly in patients with SIRS/sepsis (P < 0.001) and with neutropenic sepsis, but did not correlate with Trx or MIF levels. CONCLUSION: Plasma levels of Trx, MIF, IL-6, -8, -10 and PCT were raised in patients with SIRS/sepsis. Comparisons between mediators suggest a unique correlation of Trx with MIF. Moreover, Trx and MIF differed from cytokines and PCT in that levels were significantly lower in patients with neutropenia compared with the main SIRS/sepsis group. By contrast, IL-8 and PCT levels were significantly greater in the neutropenic patient group. The link between MIF and Trx highlighted in this study has implications for future investigations into the pathogenesis of SIRS/sepsis.

The RAGE axis in systemic inflammation, acute lung injury and myocardial dysfunction: an important therapeutic target?

BACKGROUND: The sepsis syndromes, frequently complicated by pulmonary and cardiac dysfunction, remain a major cause of death amongst the critically ill. Targeted therapies aimed at ameliorating the systemic inflammation that characterises the sepsis syndromes have largely yielded disappointing results in clinical trials. Whilst there are many potential reasons for lack of success of clinical trials, one possibility is that the pathways targeted, to date, are only modifiable very early in the course of the illness. More recent approaches have therefore attempted to identify pathways that could offer a wider therapeutic window, such as the receptor for advanced glycation end-products (RAGE) and its ligands. PURPOSE: The objectives of this study were to review the evidence supporting the role of the RAGE axis in systemic inflammation and associated acute lung injury and myocardial dysfunction, to explore some of the problems and conflicts that these RAGE studies have raised and to consider strategies by which they might be resolved. METHODS: MEDLINE was searched (1990-2010) and relevant literature collected and reviewed. RESULTS AND CONCLUSION: RAGE is an inflammation-perpetuating receptor with a diverse range of ligands. Evidence supporting a role of the RAGE axis in the pathogenesis of systemic inflammation, ALI and myocardial dysfunction is compelling with numerous animal experiments showing the beneficial effects of inhibiting the RAGE axis. Despite a number of unanswered questions that need to be further addressed, the potential for inhibiting RAGE-mediated inflammation in humans undoubtedly exists.

Severe sepsis and Toll-like receptors.

Severe sepsis dominates the mortality of non-cardiac intensive care units. The ingenious Toll-like receptor (TLR) system can recognise many infectious organisms through relatively few receptors to trigger pro-inflammatory and anti-inflammatory cytokine release. Further complexity arises from positive and negative signalling feedback loops. Severe sepsis may be a consequence of an inappropriately excessive response or inadequate endogenous negative feedback. Therapies targeting these pathways are currently being evaluated. Alternatively, in clinical scenarios such as compensatory anti-inflammatory response syndrome, chronic viral sepsis or inadequate vaccine function, TLR signalling may be inadequate. TLR agonists may augment the innate response and are being investigated.