Proteomic profiling of acute stent thrombi reveals critical involvement of the complement system

Background

Stent thrombosis (ST) is a severe complication after primary percutaneous coronary intervention (pPCI) and associated with significant morbidity and mortality. Apart from procedure- and lesion-related parameters and patient-related factors. However, the underlying molecular and cellular mechanisms of ST are still not fully understood.

Purpose

We aimed to perform in-depth proteomic analysis of ST to understand its pathogenesis.

Methods

We recruited 77 patients suffering from ST after pPCI for myocardial infarction (MI). As controls, we included matched patients suffering from native vessel acute myocardial infarction (NT, n=154). Five cases of acute ST (within 24 h) and six cases of NT thrombi aspirated from the culprit site were subjected to shotgun proteomic analysis. Gene-set analysis was employed to screen for pathways differing between ST and NT. All-cause mortality was assessed using Kaplan-Meier analysis.

Results

9 patients presented with acute ST (<24 h, 11.7%), 18 patients with subacute ST (24 h to 30 days, 23.4%), 11 patients with late ST (30 days to 1 year, 14.3%) and 39 patients with very late ST (>1 year, 50.6%). ST was associated with increased all-cause mortality compared to NT (mean survival 129 vs. 109 months, log-rank p=0.032). We identified a total of 2438 proteins to be expressed in both ST and NT thrombi. Gene set analysis revealed the complement system to be highly active in acute ST compared to NT. Specifically, we found factors of both the classical (complement factor [C]1q, C1s) and alternative pathway (complement factor B) to be increased in ST, along with higher levels of C2, C3, C4a, C4b, C5, C8a and C9.

Conclusion

This hypothesis-generating study highlights a crucial role of the complement system in the pathogenesis of acute ST. Further studies are required to validate these findings in a larger cohort.

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): Austrian Science Fund

Neutrophil extracellular traps induce MCP-1 release from endothelial cells at the plaque rupture site in acute myocardial infarction

Introduction

Leukocyte-mediated inflammation is crucial in acute myocardial infarction (AMI). We recently observed that neutrophil extracellular traps (NETs) are increased at the culprit site, promoting activation and differentiation of fibrocytes, cells with mesenchymal and leukocytic properties. Fibrocyte migration is mediated by monocyte chemoattractant protein (MCP)-1 and C-C chemokine receptor type 2 (CCR2). We investigated the interplay between NETs, fibrocyte function, and MCP-1 in AMI.

Methods

Culprit site and femoral blood of AMI patients was drawn during percutaneous coronary intervention. We characterized CCR2 expression of fibrocytes by flow cytometry. MCP-1 and the NET marker citrullinated histone H3 (citH3) were measured by ELISA. Fibrocytes were treated in vitro with MCP-1. Human coronary arterial endothelial cells (hCAECs) were stimulated with isolated NETs, and MCP-1 was measured by ELISA and qPCR. The influence of MCP-1 on NET formation in vitro was assessed using isolated neutrophils.

Results

We have included 50 consecutive AMI patients into the study. NETs and concentrations of MCP-1 were increased at the CLS. NET stimulation of hCAECs induced MCP-1 on mRNA and protein level. Increasing MCP-1 gradient was associated with fibrocyte accumulation at the site of occlusion. In the presence of higher MCP-1 these fibrocytes expressed proportionally less CCR2 than peripheral fibrocytes. In vitro, MCP-1 dose-dependently decreased fibrocyte CCR2 and reduced ex vivo NET release of healthy donor neutrophils.

Conclusions

NETs induce endothelial MCP-1 release, presumably promoting a chemotactic gradient for leukocyte and fibrocyte migration. MCP-1 mediated inhibition of NET formation could point to a negative feedback loop. These data will shed light on vascular healing.

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): Austrian Science Fund

Imbalance between plasma double-stranded DNA and deoxyribonuclease activity predicts mortality after out-of-hospital cardiac arrest

AIM

Despite an increased rate of return of spontaneous circulation (ROSC) in out-of-hospital cardiac arrest (OHCA) patients, almost half of patients do not survive up to hospital discharge. Understanding pathophysiological mechanisms of post-cardiac arrest syndrome is essential for developing novel therapeutic strategies. During systemic inflammatory responses and concomitant cell death, double-stranded (ds) DNA is released into circulation, exerting pro-inflammatory effects. Deoxyribonuclease (DNase) degrades dsDNA. The role of DNase activity in OHCA survivors and impact on clinical outcome has not been analyzed yet.

METHODS

In a prospective, single-center study, dsDNA and DNase activity were determined at hospital admission (acute phase) and 24 h (subacute phase) after ROSC. The ratio between dsDNA levels and DNase activity was calculated to determine the extent of dsDNA release in relation to the patients' capacity of degradation. Thirty-day mortality was defined as study end point.

RESULTS

We enrolled 64 OHCA survivors, of whom 26.6% (n = 17) died within 30 days. A peak of circulating dsDNA was observed at admission which decreased within 24 h. DNase activity did not differ between acute and subacute phase, while dsDNA load per DNase activity significantly decreased. The ratio between dsDNA levels and DNase activity in the subacute phase was the strongest predictor of 30-day mortality with an adjusted HR per 1 SD of 3.59 (95% CI, 1.80-7.18, p < 0.001).

CONCLUSION

Disproportionally increased dsDNA levels uncompensated by DNase activity are a strong predictor of mortality in OHCA survivors. This pilot study points to a potentially protective effect of DNase activity in patients undergoing cardiac arrest.

P6010Deficiency in milk fat globule-epidermal growth factor 8 delays thrombus resolution

Background

Chronic thromboembolic pulmonary hypertension (CTEPH) is characterized by the obstruction of pulmonary vessels by organized thrombotic and fibrotic lesions. Efferocytosis refers to the engulfment of apoptotic cells (ACs) by phagocytes, a process that is facilitated by bridging proteins. Milk fat globule-epidermal growth factor 8 (MFG-E8) connects phosphatidylserine on ACs with integrin alpha-v beta-III on phagocytes. MFG-E8-deficient mice develop auto-immune disease closely resembling systemic lupus erythematosus. In humans, decreased MFG-E8 levels were observed in patients with coronary heart disease and chronic obstructive pulmonary disease. Whether defective efferocytosis is involved in failure to resolve thrombi in CTEPH remains unknown.

Purpose

We aimed to assess whether deficiency in MFG-E8 is responsible for of chronic non-resolving thrombosis in CTEPH.

Methods

We employed a murine model of chronic thrombosis by inferior vena cava ligation, in MFG-E8 knockout (KO) or wild-type (WT) mice to assess thrombus formation and resolution. Thrombus size at days 3, 7, 14 and 28 after ligation was assessed using either histologic trichrome stainings (n=4–13 per group and time point) or in vivo high-frequency ultrasound (n=10 per group and time point). We furthermore recruited CTEPH patients (n=60, 53% female, mean age 56±11 years) and sex- and age-matched healthy controls for measurement of MFG-E8 plasma levels using ELISA. In CTEPH patients, hemodynamic measurements were performed. Human lung specimens harvested during surgery for CTEPH or from healthy controls, and isolated monocytes from whole blood of CTEPH patients or controls were analyzed using RT-qPCR.

Results

We observed substantially increased thrombus volume in MFG-E8 KO mice compared to WT, which persisted until day 14 after ligation. In human CTEPH patients, MFG-E8 in plasma was increased compared to healthy controls. Similarly, CTEPH monocytes displayed higher concentrations of MFG-E8 mRNA. Conversely, MFG-E8 expression of CTEPH pulmonary artery specimens was downregulated. No correlations between MFG-E8 levels and hemodynamic parameters were observed.

Conclusion

MFG-E8 plays an important role in thrombus resolution. In CTEPH, dysregulation of efferocytosis via impaired MFG-E8 expression in the pulmonary arteries, might drive persistence of thrombus in pulmonary arteries. The absence of a correlation between MFG-E8 and hemodynamic measures argues against pressure as a confounder of the observation.

P6396LDL cholesterol promotes neutrophil extracellular trap formation

Background

Pro-protein convertase subtilisin/kexin 9 (PCSK9) is a regulator of low density lipoprotein (LDL) receptor (LDLR) expression and has gained attention in the treatment of hyperlipidemia. Serum levels of LDL are correlated with numbers of activated neutrophils in the circulation of hyperlipidemic patients. Activated neutrophils can form neutrophil extracellular traps (NETs) by expelling their chromatin, and NETs have been recognized as important risk factors for acute myocardial infarction (AMI) and stroke.

Purpose

We analyzed the influence of serum LDL levels on neutrophil activation, their propensity to form NETs, and the correlation of NET surrogate markers with systemic inflammatory responses in AMI.

Methods

We recruited 249 consecutive patients with AMI (mean age 58 years, 20% females) and assessed laboratory parameters, inflammatory markers, and serum lipid profiles 72 h after primary percutaneous coronary intervention. Double-stranded DNA (dsDNA) and citrullinated histone H3 were determined from plasma as markers of in vivo NET formation. In a subset of patients (n=25), ex vivo NET formation in response to PCSK9 and ionomycin was analyzed, neutrophils were stained for CD11b, LDLR, and lectin-like oxidized LDLR (LOX-1) using flow cytometry at baseline and after activation with phorbol myristate acetate. PCSK9 levels were measured by ELISA.

Results

Patients with serum LDL levels above the median [median (IQR) LDL 111 mg/dl (87–141), mean ± SD LDL 115±41 mg/dl] had significantly higher concentrations of circulating dsDNA.

Levels of dsDNA [median 121 ng/ml, IQR 101–156] were linked with levels of the specific NET marker citH3 [median (IQR) 252 ng/ml (655–1600), rs=0.157]. Plasma concentrations of dsDNA and citH3 correlated significantly with CRP (dsDNA rs=0.328; citH3 rs=0.209), proBNP (dsDNA rs=0.286; citH3 rs=0.192), troponin T (dsDNA rs=0.282; citH3 rs=0.197), and IL-6 (dsDNA rs=0.242; citH3 rs=0.216).

In the subset of patients in whom neutrophils were characterized, pre-treatment of neutrophils with PCSK9 could significantly decrease ionomycin induced NET release in a dose-dependent manner. Levels of serum LDL were associated with spontaneous NET formation (r=0.504) ex vivo and activated CD11b on neutrophils (r=0.495).

LOX-1 expression correlated significantly with LDLR expression (rs=0.670) and PCSK9 levels (r=0.520). Patient neutrophil stimulation in whole blood led to a significant decrease of the LDLR positive neutrophil population. This effect was greater when PCSK9 levels were higher.

Conclusion

Our data indicate a role for LDL in boosting neutrophil activation depending on PCSK9.

The quantity and quality of α-gal-specific antibodies differ in individuals with and without delayed red meat allergy

Background

IgG to galactose‐α‐1,3‐galactose (α‐gal) are highly abundant natural antibodies (Ab) in humans. α‐Gal‐specific IgE Ab cause a special form of meat allergy characterized by severe systemic reactions 3–7 h after consumption of red meat. We investigated 20 patients who experienced such reactions and characterized their α‐gal‐specific IgE and IgG responses in more detail.

Methods

α‐Gal‐specific IgE was determined by ImmunoCAP. IgE reactivity to meat extract and bovine gamma globulin (BGG) was assessed by immunoblotting and ELISA, respectively. In some experiments, sera were pre‐incubated with α‐gal or protein G to deplete IgG Ab. α‐Gal‐specific IgG_1–4 Ab in individuals with and without meat allergy were assessed by ELISA.

Results

In immunoblots, BGG was the most frequently recognized meat protein. Binding of IgE and IgG to BGG was confirmed by ELISA and completely abolished after pre‐incubation with α‐gal. Neither the depletion of autologous α‐gal‐specific IgG Ab nor the addition of α‐gal‐specific IgG Ab from nonallergic individuals changed the IgE recognition of BGG of meat‐allergic patients. Meat‐allergic patients showed significantly higher α‐gal‐specific IgG1 and IgG3 Ab than nonallergic individuals, whereas the latter showed significantly higher levels of α‐gal‐specific IgG4 Ab.

Conclusion

Patients with delayed meat allergy display IgE and IgG Ab that selectively recognize the α‐gal epitope on BGG. Their enhanced α‐gal‐specific IgE levels are accompanied by high levels of α‐gal‐specific IgG1 devoid of IgE‐blocking activity. This subclass distribution is atypical for food allergies and distinct from natural α‐gal IgG responses in nonallergic individuals.

[Interim results for the Patients' Rights Act and Infection Protection Act]

BACKGROUND

The Patient Rights Act has converted court rulings into legal paragraphs. Two new aspects have been introduced: the duty to hand over a copy of the signed written consent form to the patient (in which detailed recommendations are offered) and the obligation of a thorough documentation of findings and treatments within patient files. In addition the legislators, through the Joint Federal Committee (Gemeinsamer Bundesausschuss, GBA) have made the introduction of clinical risk management mandatory. The Infection Protection Act and its regulations have elevated the prerequisites of hygiene within hospitals and private practices with a parallel increase in liability.

RESULTS AND DISCUSSION

Both laws and regulations offer no reference as to who (and to what extent) is financially responsible for the excessive increase in personnel costs, which are as yet not included in the German diagnosis-related groups (G-DRG) system. Despite all additional measures within the area of risk management, mistakes (avoidable or unavoidable) will nevertheless occur. In order to avoid longstanding legal battles the authors recommend an open and rapid communication with the patient and family. The wall of silence should be a thing of the past.

Typification of virulent and low virulence Babesia bigemina clones by 18S rRNA and rap-1c

The population structure of original Babesia bigemina isolates and reference strains with a defined phenotypic profile was assessed using 18S rRNA and rap-1c genes. Two reference strains, BbiS2P-c (virulent) and BbiS1A-c (low virulence), were biologically cloned in vitro. The virulence profile of the strains and clones was assessed in vivo. One fully virulent and one low-virulence clone were mixed in identical proportions to evaluate their growth efficiency in vitro. Each clone was differentiated by two microsatellites and the gene gp45. The 18S rRNA and rap-1c genes sequences from B. bigemina biological clones and their parental strains, multiplied exclusively in vivo or in vitro, were compared with strain JG-29. The virulence of clones derived from the BbiS2P-c strain was variable. Virulent clone Bbi9P1 grew more efficiently in vitro than did the low-virulence clone Bbi2A1. The haplotypes generated by the nucleotide polymorphism, localized in the V4 region of the 18S rRNA, allowed the identification of three genotypes. The rap-1c haplotypes allowed defining four genotypes. Parental and original strains were defined by multiple haplotypes identified in both genes. The rap-1c gene, analyzed by high-resolution melting (HRM), allowed discrimination between two genotypes according to their phenotype, and both were different from JG-29. B. bigemina biological clones made it possible to define the population structure of isolates and strains. The polymorphic regions of the 18S rRNA and rap-1c genes allowed the identification of different subpopulations within original B. bigemina isolates by the definition of several haplotypes and the differentiation of fully virulent from low virulence clones.

Origin and course of the extracranial vertebral artery: CTA findings and embryologic considerations

PURPOSE

The aim of this study was to show the different origins and courses of the extracranial VA on CTA with special emphasis on embryological considerations. The duplicated VA is an anomaly that has been assumed to predispose for dissection and to be associated with aneurysms. We report its frequency and clinical significance.

METHODS

We retrospectively reviewed CTA of 539 patients by using a contrast-enhanced CTA protocol of the VA on CT.

RESULTS

Ninety-four-point-two percent of left VA originated from left subclavian artery and entered the transverse foramen at C6 in nearly all cases. Six-point-three-percent of left VA (m = 4 %, f  = 10 %) originated from the aortic arch and entered the transverse foramen either at C4, C5 or C7 but never at C6. One case of an aberrant retroesophageal right VA originated from the aortic arch distal to the left subclavian artery and entered at C7 (0.19 %). All other right VA originated from the right subclavian artery (99.8 %) and entered between C4 and C6. We diagnosed four cases of duplicated VA (0.74 %) with a female predominance (1.9 %) without any signs of dissection on CTA. Two cases with VA duplication had intracranial arterial aneurysms.

CONCLUSIONS

The VA is a longitudinal anastomosis of segmental metameric arteries. The level of entrance into the transverse foramen indicates which metameric artery or arteries persist. Duplication corresponds to persistence of two segmental arteries and is a rare phenomenon. VA duplication might be associated with vascular lesions.

Anti-Gal titers in healthy adults and inflammatory bowel disease patients

INTRODUCTION

ALPHA-GAL is a glycoconjugate present on cell membranes of mammals and bacteria but not humans who display anti-Gal antibodies (AB) in high titers provoked by the commensal gut flora. In the present study, we sought to determine the longitudinal course of alpha-Gal specific AB titers of all isotypes over 8 weeks among healthy adult subjects. Furthermore, we hypothesized that inflammatory bowel disease (IBD) patients display increased anti-Gal titers.

MATERIALS AND METHODS

We drew serum from healthy probands (n=20) weekly for 8 weeks and obtained plasma samples of from patients suffering from Crohn's disease (n=20) and ulcerative colitis (n=20). We measured anti-Gal ABs of all isotypes and total immunoglobulin (Ig) content using an enzyme-linked immunosorbent assay technique. For statistical evaluation of the longitudinal titers, we calculated confidence intervals for the slopes of a random intercept model, comparing variances between and within the probands. For group comparisons, we performed paired student t-tests and Pearson correlations.

RESULTS

Alpha-Gal specific IgG, IgM, IgD, and IgA titers remained unvaried within a narrow range upon longitudinal observation. Most probands did not display alpha-Gal specific IgE ABs. Crohn's disease patients showed highly increased alpha-Gal-specific IgA titers compared with control subjects (P<.01).

CONCLUSION

Apart from IgE, alpha-Gal-specific ABs of all isotypes remained constant over longer time periods in healthy subjects. Thus, significant titer changes actually represent increased antigen exposure and a specific anti-alpha-Gal response. Crohn's disease patients display increased anti-Gal IgA titers compared with healthy controls, which reflects a chronically impaired mucosal gut barrier in this patient cohort.

Ornithodoros peruvianus Kohls, Clifford & Jones (Ixodoidea: Argasidae) in Chile: a tentative diagnosis

Three argasid tick larvae were collected on April 2, 2010, from a common vampire bat, Desmodus rotundus, captured in the Parque Nacional Pan de Azúcar (26°09' S, 70°41' W), Region of Atacama, Chile. The larvae were diagnosed as Ornithodoros, and further comparative analysis showed them to be Ornithodoros peruvianus Kohls, Clifford & Jones or a species close to it. Phylogenetic analysis based on 16S mitochondrial rRNA gene sequences of Ornithodoros species plus four Argas species was carried out to clarify the taxonomic position of the larvae. This is the first finding of ticks parasitizing D. rotundus in Chile.

Secretion of soluble ST2 - possible explanation for systemic immunosuppression after heart surgery

BACKGROUND

Cardiopulmonary bypass is known to affect cytokine release leading to a generalized endogenous immune reaction similar to that described in sepsis, without having been explored in great detail. Therefore we evaluated the anti- and pro-inflammatory cytokine responses after heart surgery.

METHODS

16 patients who underwent coronary artery bypass graft (CABG) surgery with extracorporeal circulation were included. ST2, IL-4 and IL-10 served as markers for TH2 cytokine response; IL-6, IL-8 and IFN-gamma as TH1 markers. Furthermore, total immunoglobulin subtype analysis (IgM, IgG, IgE) was performed.

RESULTS

Serum levels of soluble ST2 started to climb at 60 minutes (from 38 +/- 14 preoperatively to 1 480 +/- 890 pg/ml) and peaked 24 hours after surgery (13 360 +/- 2 840 pg/ml, P < 0.001). IL-10 reached a maximum at 60 minutes and returned to baseline levels 24 hours later. IL-6 and IL-8 levels peaked 60 minutes after surgery. IL-4 and IFN-gamma did not change. Only IgM showed a significant peak on day eight ( P < 0.001).

CONCLUSION

Our results demonstrate that CABG surgery induces a massive long-lasting secretion of ST2, a protein related to immune suppression.

Cytomegalovirus hyperimmunoglobulin: mechanisms in allo-immune response in vitro

BACKGROUND

Cytomegalovirus hyperimmunoglobulin (CMVIg) containing drugs are routinely administered in cardiac transplantation for prophylaxis against CMV disease. Yet little is known about their influence on transplant relevant immune functions. The aim of this study was to evaluate the effect of CMVIg on cellular immunity in in vitro experiments and to define their role in tolerance inducing mechanisms.

MATERIALS AND METHODS/RESULTS

CMVIg reduces proliferation in mixed lymphocyte reactions and anti-CD3 blastogenesis assays and is related to decreased production of immune modulating cytokines interleukin (IL)-2, interferonr (IFNgamma), IL-10. This antiproliferative effect is associated with a cell-cycle arrest in the G0/G1 phase and induction of apoptosis in CD8+ and natural killer cells. Co-incubation with CMVIg causes down-regulation of cell bound immunoglobulin and FcgammaRIII surface expression on natural killer cells and leads to attenuation of antibody dependent cellular cytotoxicity effector functions.

CONCLUSIONS

We conclude that CMVIg induces immunological features on leukocytes in vitro that are known to be related to tolerance induction. Our observations extend the current concept of CMVIg as passive CMV prophylaxis to a therapeutic drug compound capable of reducing allogeneic immune response.

[Peripheral facial palsy as the first symptom of a metastatic bronchogenic carcinoma]

BACKGROUND

We present a case of a facial palsy as the initial symptom of a bronchogenic carcinoma.

METHODS

Case-report. A 56-year-old patient presented with a peripheral facial palsy. The clinical picture as well as the temporal bone CT were without pathological findings. A 10-day rheologic therapy as well as anti-viral medication were not successful. Five days after rheological therapy had been completed, the patient presented a swelling of the neck. In the computer tomography we found a bilateral thrombosis of the internal jugular vein. In addition, the clinical picture of a left-sided glossopharyngeal palsy appeared. The following thorax CT as well as the diagnostic extirpation of an enlarged cervical lymph node lead to the diagnosis of a metastasized smallcell neuro-endocrine bronchogenic carcinoma with a compression of the right primary bronchus and the vena cava superior as well as an upper inflow congestion. In the cMRT we furthermore found a metastasis in the area of the foramen stylomastoideum. The patient underwent emergency radiation and chemotherapy.

RESULTS

According to the present findings, this metastasis lead to the facial palsy as the initial symptom of the bronchogenic carcinoma.

CONCLUSION

Therefore, therapy resistant facial palsy should be further diagnosed in detail, especially examined by imaging procedures.