Comparison of mouse models of microbial experience reveals differences in microbial diversity and response to vaccination

Specific pathogen-free (SPF) laboratory mice dominate preclinical studies for immunology and vaccinology. Unfortunately, SPF mice often fail to accurately model human responses to vaccination and other immunological perturbations. Several groups have taken different approaches to introduce additional microbial experience to SPF mice to better model human immune experience. How these different models compare is unknown. Here, we directly compare three models: housing SPF mice in a microbe-rich barn-like environment (feralizing), adding wild-caught mice to the barn-like environment (fer-cohoused), or cohousing SPF mice with pet store mice in a barrier facility (pet-cohoused); the two latter representing different murine sources of microbial transmission. Pet-cohousing mice resulted in the greatest microbial exposure. Feralizing alone did not result in the transmission of any pathogens tested, while fer-cohousing resulted in the transmission of several picornaviruses. Murine astrovirus 2, the most common pathogen from pet store mice, was absent from the other two model systems. Previously, we had shown that pet-cohousing reduced the antibody response to vaccination compared with SPF mice. This was not recapitulated in either the feralized or fer-cohoused mice. These data indicate that not all dirty mouse models are equivalent in either microbial experience or immune responses to vaccination. These disparities suggest that more cross model comparisons are needed but also represent opportunities to uncover microbe combination-specific phenotypes and develop more refined experimental models. Given the breadth of microbes encountered by humans across the globe, multiple model systems may be needed to accurately recapitulate heterogenous human immune responses.IMPORTANCEAnimal models are an essential tool for evaluating clinical interventions. Unfortunately, they can often fail to accurately predict outcomes when translated into humans. This failure is due in part to a lack of natural infections experienced by most laboratory animals. To improve the mouse model, we and others have exposed laboratory mice to microbes they would experience in the wild. Although these models have been growing in popularity, these different models have not been specifically compared. Here, we directly compare how three different models of microbial experience impact the immune response to influenza vaccination. We find that these models are not the same and that the degree of microbial exposure affects the magnitude of the response to vaccination. These results provide an opportunity for the field to continue comparing and contrasting these systems to determine which models best recapitulate different aspects of the human condition.

Dietary intake of micronized avian eggshell membrane in aged mice reduces circulating inflammatory markers, increases microbiota diversity, and attenuates skeletal muscle aging

Introduction

Avian eggshell membrane (ESM) is a complex extracellular matrix comprising collagens, glycoproteins, proteoglycans, and hyaluronic acid. We have previously demonstrated that ESM possesses anti-inflammatory properties in vitro and regulates wound healing processes in vivo. The present study aimed to investigate if oral intake of micronized ESM could attenuate skeletal muscle aging associated with beneficial alterations in gut microbiota profile and reduced inflammation.

Methods

Elderly male C57BL/6 mice were fed an AIN93G diet supplemented with 0, 0.1, 1, or 8% ESM. Young mice were used as reference. The digestibility of ESM was investigated using the static in vitro digestion model INFOGEST for older people and adults, and the gut microbiota profile was analyzed in mice. In addition, we performed a small-scale pre-clinical human study with healthy home-dwelling elderly (>70 years) who received capsules with a placebo or 500 mg ESM every day for 4 weeks and studied the effect on circulating inflammatory markers.

Results and discussion

Intake of ESM in elderly mice impacted and attenuated several well-known hallmarks of aging, such as a reduction in the number of skeletal muscle fibers, the appearance of centronucleated fibers, a decrease in type IIa/IIx fiber type proportion, reduced gene expression of satellite cell markers Sdc3 and Pax7 and increased gene expression of the muscle atrophy marker Fbxo32. Similarly, a transition toward the phenotypic characteristics of young mice was observed for several proteins involved in cellular processes and metabolism. The digestibility of ESM was poor, especially for the elderly condition. Furthermore, our experiments showed that mice fed with 8% ESM had increased gut microbiota diversity and altered microbiota composition compared with the other groups. ESM in the diet also lowered the expression of the inflammation marker TNFA in mice and in vitro in THP-1 macrophages. In the human study, intake of ESM capsules significantly reduced the inflammatory marker CRP. Altogether, our results suggest that ESM, a natural extracellular biomaterial, may be attractive as a nutraceutical candidate with a possible effect on skeletal muscle aging possibly through its immunomodulating effect or gut microbiota.

Microbial experience through housing in a farmyard-type environment alters intestinal barrier properties in mouse colons

To close the gap between ultra-hygienic research mouse models and the much more environmentally exposed conditions of humans, we have established a system where laboratory mice are raised under a full set of environmental factors present in a naturalistic, farmyard-type habitat-a process we have called feralization. In previous studies we have shown that feralized (Fer) mice were protected against colorectal cancer when compared to conventionally reared laboratory mice (Lab). However, the protective mechanisms remain to be elucidated. Disruption of the protective intestinal barrier is an acknowledged player in colorectal carcinogenesis, and in the current study we assessed colonic mucosal barrier properties in healthy, feralized C57BL/6JRj male mice. While we found no effect of feralization on mucus layer properties, higher expression of genes encoding the mucus components Fcgbp and Clca1 still suggested mucus enforcement due to feralization. Genes encoding other proteins known to be involved in bacterial defense (Itln1, Ang1, Retnlb) and inflammatory mechanisms (Zbp1, Gsdmc2) were also higher expressed in feralized mice, further suggesting that the Fer mice have an altered intestinal mucosal barrier. These findings demonstrate that microbial experience conferred by housing in a farmyard-type environment alters the intestinal barrier properties in mice possibly leading to a more robust protection against disease. Future studies to unravel regulatory roles of feralization on intestinal barrier should aim to conduct proteomic analyses and in vivo performance of the feralized mice intestinal barrier.

Effects of omega-3 fatty acid supplementation on the risk of atrial fibrillation (AF) and micro-AF in the OMEMI trial

Background

Findings from recent clinical outcome trials have raised concerns regarding potential off target adverse effects from supplementation with n-3 polyunsaturated fatty acids (PUFA) on atrial fibrillation (AF) risk.

Purpose

We aimed to assess AF and “micro-AF” in elderly patients with myocardial infarction (MI), randomized to n-3 PUFA or placebo.

Methods

In the OMEMI trial, 70–82 years old patients with a recent MI were randomized to 1.8g/day of eicosapentaenoic/docosahexaenoic acid (EPA/DHA) or placebo (corn oil) for two years. New-onset AF was recorded by clinical detection and by screening, also for “micro-AF” (episodes of ≥3 consecutive irregular supraventricular ectopic beats), by two weeks Zenicor thumb ECG (adjudicated by investigators blinded to treatment allocation). Serum phospholipid content of EPA and DHA was determined by gas chromatography at baseline and study end.

Results

Of 1014 patients in the OMEMI trial, 759 (75%) had no history of AF at baseline. These patients were aged 75±4 years and 542 (71%) were male. During the two year follow-up 43 patients developed new-onset AF (39 clinically-detected and 4 by thumb-ECG screening). In addition, 27 patients had episodes of micro-AF, yielding a total of 70 patients with new-onset AF or micro-AF. In the n-3 PUFA group 46 (11.9%) had AF/micro-AF (28 AF and 18 micro-AF) while in the placebo group 24 (6.5%) had AF/micro-AF (15 AF and 9 micro-AF); HR 1.90 (95% CI 1.16–3.11, P=0.011; Figure 1, panel A). In both treatment arms combined, EPA increased with a mean of 60% in no-AF, 80% in micro-AF and 110% in AF (P=0.003 for linear trend; Figure 1, panel B). In patients randomized to n-3 PUFA, EPA increased with a mean of 120% in no-AF, 130% in micro-AF and 180% in clinical-AF (P=0.04 for linear trend). There were no significant associations between changes in DHA and new-onset AF.

Conclusion

Supplementation with 1.8 g of n-3 PUFA to post MI patients increased the risk of micro-AF and AF, and there seemed to be a graded association between increases in serum EPA and the risk of micro-AF and AF. Changes in serum DHA was not related to the risk of AF/micro-AF.

Funding Acknowledgement

Type of funding sources: None.

Screen-detected atrial fibrillation (AF) and “micro-AF” after myocardial infarction in patients 70–82 years and risk of cardiovascular events in the OMEMI trial

Background

Incident atrial fibrillation (AF) occurs in 5–10% of patients after acute myocardial infarction (AMI) and is associated with adverse outcomes. Guidelines now recommend screening for AF in all elderly patients. However, the yield of extended AF screening after AMI has not been investigated. Short episodes of consecutive irregular supraventricular ectopic beats, entitled “micro-AF”, are associated with the development of AF, but the prognostic importance of such findings after an AMI is unknown.

Purpose

To investigate the added value of two-week intermittent ECG screening to detect incident AF and “micro-AF” in elderly patients 12 months after an AMI, and its relation to risk of cardiovascular endpoints.

Methods

The OMega-3 fatty acids in Elderly patients with Myocardial Infarction (OMEMI) study investigated the effect of Omega-3 fatty acid supplementation on 2-year risk of major cardiovascular events (MACE; non-fatal AMI, stroke, revascularization, or hospitalization for heart failure) in 70–82 years old patients with a recent AMI. All patients had a 12-lead ECG performed at 3, 12 and 24 months. In addition, patients without known AF one year after the index AMI underwent a 2-week period of intermittent 30-second “thumb ECG” screening. Incident AF and “micro-AF” (episodes of ≥3 consecutive irregular supraventricular ectopic beats) were registered and adjudicated by at least two investigators who were blinded to outcome, and the association with risk of MACE was analyzed with logistic regression.

Results

Among 1014 patients in the OMEMI trial, 255 (25.1%) had known AF or AF identified at baseline. New-onset AF was detected clinically or at study visits in 39 patients. Screening by 2-week “thumb ECG” was performed in 567 participants without known AF, and identified unknown AF in 4 (0.7%) patients. Another 27 (4.8%) patients had “micro-AF” in at least one ECG recording. In 43 patients with incident AF, 21 (48.8%) experienced a MACE, compared to 114 out of 716 without any AF (15.9%; p<0.001), driven by a higher risk of new AMI or revascularization. Nine (33.3%) patients with “micro-AF” and 63 (12.2%) without “micro-AF” experienced a MACE (p=0.002), explained mostly by a higher risk of hospitalization for heart failure (p<0.001). Using patients without AF and “micro-AF” as reference, “micro-AF” was associated with an intermediate risk of MACE (OR 2.8: 95% CI 1.2–6.4) and new-onset AF with a high risk of MACE (OR 5.3; 95% CI 2.8–10.0).

Conclusion

Two-week intermittent ECG screening identified few new cases of new-onset AF, but a substantial number of patients with “micro-AF”. “Micro-AF” was associated with an increased risk of major cardiovascular events, albeit with an intermediate risk compared to a higher risk of major cardiovascular events associated with new-onset AF.

Funding Acknowledgement

Type of funding sources: None.

Effect of Revascularization on Exercise-Induced Changes in Cardiac and Prothrombotic Biomarkers in Patients with Coronary Artery Disease

We examined whether resting levels and exercise-induced changes during exercise ECG stress test (EST) of cardiac Troponin T (cTnT), NT-proBNP and prothrombotic markers were affected by revascularization in patients with coronary artery disease (CAD).

EST1 was performed before coronary angiography and revascularization, and patients (n  =  20) with confirmed CAD, performed another EST (EST2) 9 weeks later. Blood samples were drawn at rest and within five min after termination of ESTs.

cTnT and NT-proBNP increased during exercise at both ESTs (p < 0.001, all). Resting cTnT levels at EST2 versus EST1 were significantly higher (p  =  0.02) whereas NT-proBNP did not differ. At both visits, increased D-dimer (p  =  0.008 and <0.001), pro-thrombin fragment 1  +  2 (p  =  0.009 and 0.001) and tissue factor pathway inhibitor (TFPI) (p < 0.001 and 0.001) during exercise were demonstrated. Resting levels of endogenous thrombin potential (ETP) and TFPI were reduced at EST2 versus EST1 (p < 0.01).

Revascularization did not affect exercise-induced release of cardiac and prothrombotic biomarkers and did not reduce resting levels of cTnT or NT-proBNP, suggesting revascularization per se not to prevent secretion of biomarkers. The lower resting levels of ETP and TFPI after revascularization may however, be indicative of reduced thrombin generation and endothelial activation.

Clinicaltrials.gov, CADENCE, NCT01495091 https://clinicaltrials.gov/ct2/show/NCT01495091?term = 01495091&draw = 2&rank = 1.

Complement activation is associated with neutrophil extracellular traps and all-cause mortality in ST-elevation myocardial infarction

Background

The complement system and neutrophil extracellular traps (NETs) are both parts of the innate immune system, and have been implicated in the ischemia-reperfusion injury in patients with ST-elevation myocardial infarction (STEMI). There is experimental evidence of reciprocal activation between the complement system and NETs. Any such link in patients with STEMI has not been investigated.

Purpose

To investigate a potential association between complement activation and clinical outcomes after STEMI, and assess any interplay between complement activation and NETs in this situation.

Methods

Patients with ST-elevation myocardial infarction were included at a median of 18 hours after percutaneous coronary intervention (n=864). The terminal complement complex (TCC) was measured by ELISA as a marker of complement activation. As markers of NETs were myeloperoxidase-deoxynucleic acid (MPO-DNA) and citrullinated histone 3 (CitH3) measured by ELISAs, while double stranded DNA (dsDNA) was measured by a nucleic acid stain. Patients were followed for a median of 4.6 years. The primary endpoint was a composite of new myocardial infarction, unscheduled revascularization, stroke, hospitalization for heart failure and death, whichever occurred first. All-cause mortality was also recorded.

Results

The composite endpoint occurred in 184 (21.3%) patients, while 70 (8.1%) died during follow-up. When dichotomizing at median TCC, the group with above-median TCC levels did not have an increased risk of reaching the composite endpoint (hazard ratio (HR): 1.069, 95% CI: [0.801, 1.428], p=0.651). However, this group exhibited an increased risk of all-cause mortality (HR: 1.650, 95% CI: [1.020, 2.671], p=0.041). This risk persisted when adjusting for age, sex, hypertension and LDL-cholesterol (HR: 1.673, 95% CI: [1.014, 2.761], p=0.044), but the significance was lost when adjusting for NT-proBNP (HR: 1.492, 95% CI: [0.885, 2.515], p=0.133). TCC was correlated to dsDNA (r=0.127, p&lt;0.001) and CitH3 (r=0.102, p=0.003), but not MPO-DNA. The group with both TCC and dsDNA in the highest quartile exhibited a significantly higher incidence of all-cause mortality than the remaining population (17.6% vs, 7.2%, p=0.002). When examining the predictive value of TCC and dsDNA on all-cause mortality in ROC curve analysis, the area under the curve (AUC) for TCC was 0.549 (95% CI: [0.472, 0.625]), while the AUC for dsDNA was 0.653 (95% CI: [0.584, 0.722]). When combining TCC and dsDNA the predictive value was marginally higher than for TCC alone (AUC: 0.649, 95% CI: [0.579, 0.720])

Conclusion

In this STEMI population, complement activation measured by TCC was not associated with the primary composite endpoint, but was associated with increased risk of death. TCC was weakly correlated with markers of NETs. Despite a high mortality rate in patients with high levels of TCC and dsDNA, combining these variables did not increase the prognostic value compared to TCC alone.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): Stein Erik Hagen's Foundation for Clinical Heart Research Survival according to cox regression

Changes in EPA and DHA during supplementation with omega-3 fatty acids and incident cardiovascular events: secondary analysis from the OMEMI trial

Background

In the OMEMI trial, elderly post-MI patients did not achieve reduction in cardiovascular events from supplementation of 1.8g n-3 polyunsaturated fatty acids (PUFA). In two recent trials of hypertriglyceridaemic patients the REDUCE-IT trial demonstrated an association between high levels of serum eicosapentaenoic acid (EPA) and reduced risk of CV events with 4 g/day icosapent ethyl supplements while in the STRENGTH trial no such association was present in patients treated with 4 g/day of EPA+ docosahexaenoic acid (DHA).

Purpose

To assess associations between changes in concentrations of EPA and DHA during two years supplementation with n-3 PUFA and incident cardiovascular events in the OMEMI trial.

Methods

In the randomized controlled OMEMI trial, 1014 elderly patients with a recent acute myocardial infarction (AMI) were treated with 1.8g/day of EPA and docosahexaenoic acid (DHA) or placebo for two years, and followed for the primary outcome of MACE (AMI, coronary revascularization, stroke or heart failure hospitalization) and secondary outcome of new-onset atrial fibrillation (AF). Serum concentrations of EPA and DHA were measured at inclusion and at study completion by gas chromatography, and reported as % weight of total FA (%wt) in serum phospholipids.

Results

Serial EPA and DHA measurements at study inclusion and completion were available in 881 patients (92% of survivors). At baseline EPA and DHA concentrations were (mean±SD) 2.84±1.41 and 5.71±1.35%wt, respectively. Higher baseline EPA and DHA concentrations were associated with previous n-3 PUFA supplementation, lower prevalence of current smoking and diabetes, lower levels of triglycerides and higher levels of HDL-cholesterol (all p&lt;0.05). In patients randomized to n-3 PUFA, EPA and DHA increased with 2.32±1.92 and 0.91±1.19%wt, respectively, whereas in the placebo group EPA and DHA decreased with −0.39±1.37 and −0.43±1.13%wt, respectively. Greater increases in EPA and DHA during follow-up were associated with a lowering of triglyceride concentrations, increasing HDL concentrations, and lower baseline concentrations of EPA and DHA (all p&lt;0.001). Among patients treated with n-3 PUFA (n=438), a greater increase in EPA was associated with a lower risk of incident MACE (HR 0.89 [95% CI 0.78–1.00] per %wt, p=0.059) and higher risk of new-onset AF in patients free of AF at inclusion (n=339): HR 1.31 [1.06–1.62] per %wt, p=0.012 (Figure). There were no such associations for changes in DHA: HR 0.86 (95% CI 0.70–1.05), p=0.13 for MACE and HR 1.29 (0.91–1.83), p=0.16 for new-onset AF.

Conclusion

Patients treated with 1.8 g/day n-3 PUFA for two years experienced a doubling of serum EPA concentrations. Greater increases in EPA were associated with a lower risk of MACE, but also a higher risk of new-onset AF. Changes in DHA concentrations were not associated with outcomes, suggesting that EPA may be the more important n-3 PUFA with respect to risk of cardiovascular events.

Funding Acknowledgement

Type of funding sources: Public hospital(s). Main funding source(s): Oslo University Hospital, Ullevål Figure 1

Plaque and remodeling markers in coronary thrombi

Background

Matrix Metalloproteinases (MMPs) and their inhibitors are considered to be of importance in development of atherosclerotic coronary artery disease. MMP-9 has been associated with unstable atherosclerotic plaques and rupture, as well as left ventricular remodeling after myocardial infarction (MI), whereas MMP-2 seems to be more related to progression of stable plaques. MMP activity is modulated by Tissue Inhibitors of Metalloproteinases (TIMPs). TIMP-1 has been associated with cardiac remodeling post MI, and TIMP-2 has been discussed to inhibit plaque development and destabilization. The extracellular MMP Inducer, EMMPRIN, stimulates both MMPs and TIMPs, and has been found upregulated on the surface of monocytes in patients with acute MI, and associated with MMP-9 activity.

Purpose

To study whether genes encoding MMP-2, MMP-9, TIMP-1, TIMP-2 and EMMPRIN are expressed in coronary thrombi and in circulating leukocytes from STEMI patients, and whether these are related to the degree of myocardial injury measured by troponin T, and time from symptoms to PCI.

Methods

Intracoronary thrombi were aspirated from 33 patients with ST-elevation myocardial infarction (STEMI) treated with primary PCI. The thrombi were snap-frozen in RNA-later solution for gene expression analyses. Peripheral blood samples with Pax-gene tubes were drawn at end of the PCI procedure. RNA was isolated from the thrombi and leukocytes, and the actual genes relatively quantified by RT PCR. Peak troponin T was collected from clinical records.

Results

Genes coding for the five different markers were present in 84–100% of the thrombi. Median peak troponin T was 3434 m/L. The expression of TIMP-1 in the thrombi correlated significantly to peak troponin T (r=0.393, p=0.026), and dividing peak troponin T values into quartiles, the median value of TIMP-1 mRNA in Q4 was 2.5-fold higher compared to Q1–3 (p=0.107). Peak troponin T also correlated to the expression of TIMP-1 in circulating leukocytes (r=0.469, p=0.006), and in Q4 of troponin T, the median value was 1.6-fold higher compared to Q1–3 (p=0.056). There were no significant correlations between the other measured genes and troponin T, and also no associations of any genes expressed in the thrombi or in circulating leukocytes to time from symptom to PCI (median 152 min).

Conclusion

Genes coding for MMP-2, MMP-9, TIMP-1, TIMP-2 and EMMPRIN were highly expressed in human coronary thrombi. The positive correlation between peak troponin T and the expression of TIMP-1 both in thrombi and in circulating leukocytes at time of PCI in patients with STEMI, may indicate that the role of TIMP-1 is important in cardiac remodeling immediately post-MI.

Funding Acknowledgement

Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): Stein Erik Hagens Foundation for Clinical Heart Research

Effect of revascularization on exercise-induced changes in cardiac and pro-thrombotic biomarkers in patients with coronary artery disease

Introduction

Exercise-induced increase in cardiac and pro-thrombotic biomarkers have previously been shown in patients with coronary artery disease (CAD) before revascularization, which may be due to myocardial ischemia.

Purpose

We aimed to examine whether resting levels and exercise-induced changes of high sensitive cardiac Troponin T (cTnT), NT-proBNP, pro-thrombin fragment (F) 1+2, D-dimer, tissue factor pathway inhibitor (TFPI) and endogenous thrombin potential (ETP) were affected by revascularization in patients with CAD. We hypothesized that resting and exercise-induced levels of the biomarkers would be reduced after revascularization.

Methods

Patients presenting with symptoms of CAD were included. A maximal exercise ECG stress test (EST) (EST1) was performed, and venous blood samples were drawn at rest and within five min after termination. All patients underwent coronary angiography. Patients (n=20) with confirmed CAD, fully revascularized with percutaneous coronary intervention (PCI) and without symptoms of angina, were invited to perform a second EST (EST2), at the same workload (median 145W), at a median of 66 days after revascularization. Mean exercise duration at both time points were 11:30 min:sec. Of the total population 15 patients were treated with PCI on stenosis located on LAD and 5 patients with stenosis on RCA.

Results

Significant increase in cTnT and NT-proBNP from resting to post exercise levels at EST1 was found as expected (p&lt;0.001, both). Also at EST2, increased levels were observed (p&lt;0.01, both), however, not significantly different from the changes at EST1. Resting levels of cTnT at EST2 compared to EST1 were significantly higher (median 8.1 vs 7.1 ng/L, p=0.02). At both visits significant increase in D-dimer (p=0.008 and &lt;0.001), F1+2 (p=0.009 and 0.001) and TFPI (p&lt;0.001 and 0.001) during exercise were demonstrated, with no difference in these changes. There were no significant changes in ETP during exercise at any visit, but resting levels were reduced at EST2 vs EST1 (p&lt;0.01). Also resting levels of TFPI were reduced at EST2 (p&lt;0.01).

Conclusion

After revascularization there was still significant increase in exercise-induced release of cardiac and pro-thrombotic biomarkers, thus revascularization does not affect the ability to release these biomarkers. Also, the higher resting levels of cTnT after revascularization indicate that revascularization per se does not affect secretion of cardiac biomarkers, probably due to the disease state. The lower resting levels of ETP and TFPI after revascularization may, however, be indicative of reduced thrombin generation potential and endothelial activation.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): Stein Erik Hagens Foundation for Clinical Heart Research, Oslo, Norway

Gut leakage markers in response to strenuous exercise in patients with suspected coronary artery disease

Introduction

Although regular physical activity is associated with reduced risk of cardiovascular disease (CVD), acute vigorous exercise seems to transiently increase the risk of acute coronary events in patients with underlying CVD. Some studies have reported regular physical activity to associate with microbial diversity, whereas elevated levels of gut leakage markers have been shown after strenuous exercise in healthy individuals. Any predictive value of a temporary increase in gut leakage markers on the risk of coronary events in susceptible individuals is unknown.

Purpose

We aimed to explore gut leakage markers in response to a bout of strenuous exercise in patients with symptoms of chronic coronary syndrome (CCS). We hypothesized that gut leakage markers would increase after acute strenuous exercise, and that the increase would be higher in patients with angiographically verified CAD.

Methods

Patients referred to exercise stress testing or coronary angiography due to symptoms suggestive of CCS were included (n=327). A maximal exercise ECG stress test was performed using a bicycle ergometer. Venous blood samples were drawn at rest prior to the test and within 5 min after the test ended, for analysis of soluble cluster of differentiation 14 (sCD14), lipopolysaccharide-binding protein (LBP) and intestinal fatty-acid binding protein (I-FABP) by ELISAs. Quantification of lipopolysaccharide (LPS) and relative quantification of gene expression of the toll-like receptor 4 (TLR4) in circulating leukocytes was performed in a subset of patients (n=101). Patients then underwent coronary angiography, and were grouped according to the degree of CAD.

Results

Of the 287 patients who completed the exercise stress test and coronary angiography, 69 (24%) had no CAD, 88 (31%) had non-significant CAD and 130 (45%) had significant CAD. Mean exercise duration was 10:05±4:46 min and the duration did not differ between the groups. There were no significant differences in resting levels of gut leakage markers between the groups. In the total population, sCD14, LBP and LPS increased significantly after exercise (p&lt;0.0001, all), whereas I-FABP did not. The gene expression of TLR4 decreased significantly after exercise (p&lt;0.0001). There were no differences in exercise-induced changes in any of the measured markers between groups with no CAD, non-significant CAD and significant CAD.

Conclusion

In patients with symptoms suggestive of CCS, LPS, LBP and sCD14 increased significantly after strenuous exercise, suggesting that even short bouts of vigorous exercise are associated with gut leakage. The decrease in gene expression of TLR4 may be discussed to be compensatory to the increase in LPS or possibly reflecting an increase in TLR4 translation in response to LPS. The presence of CAD or not did not seem to impact exercise-induced increase in gut leakage markers.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): Stein Erik Hagen Foundation for Clinical Heart Research, Olso, Norway

Low levels of dihomo-gamma-linolenic acid are associated with all-cause death in elderly patients with a recent myocardial infarction

Background

In a previous study*, low levels of the omega-6 fatty acid (FA) dihomo-gamma (γ)-linolenic acid (DGLA; C20:3w6), were independently associated with poor 7-year outcome in elderly patients after acute coronary syndrome.

Aim

In order to further evaluate DGLA as a predictor of outcome, we measured n-6 FAs including DGLA in serum samples from elderly subjects with a recent acute myocardial infarction (AMI).

Methods

Baseline samples from the OMEMI (Omega-3 Fatty acids in Elderly with Myocardial Infarction) trial* in which a total of 1027 patients, aged 70 to 82 years, were included 2–8 weeks after an MI, were used. The pre-specified primary outcome during 2 years follow-up was major adverse cardiac events (MACE), which consisted of nonfatal MI, unscheduled coronary revascularization, stroke, all-cause death, or hospitalization for heart failure. Cox regression analysis was used to relate serum n-6 FA levels, measured by gas chromatography and reported as % weight of total FA (%wt) to the risk of incident cardiovascular events. Three models were employed in the multivariable analysis, adjusting for: 1) age, sex and body mass index; 2) + baseline omega-3 FA supplementation; 3) + prevalent hypertension.

Results

Median DGLA levels at baseline (n=1.002) were 2.89 (Q1–Q3 2.43–3.38) %wt. After 2 years follow-up, 152 patients experienced incident MACE, including n=55 all-cause death.

The univariate hazard ratio (HR) for MACE, employing continuous DGLA values was 0.89 (95% CI 0.72–1.08) per %wt increase in DGLA, p=0.24, and for all-cause death 0.72 (95% CI 0.48–1.07), p=0.11. In the multivariable Cox regression models for MACE, concentrations of DGLA did not reach statistical significance; p=0.12, 0.09 and p=0.07 in Models 1, 2 and 3, respectively.

In univariate analysis, HR for total death in the three higher quartiles of DGLA as compared to the lowest quartile was 0.51 (95% CI 0.30–0.80), p=0.016. Results remained statistically significant in all the multivariable models. Model 1: HR 0.54 (0.31–0.95), p=0.03; Model 2: HR 0.50 (0.28–0.91) p=0.02; Model 3: HR 0.49 (0.27–0.88), p=0.017.

Conclusion

Low serum levels of DGLA were associated with increased risk of all-cause death after AMI in elderly patients, thus, suggesting DGLA to be protective.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): Stein Erik Hagen Foundation for Clinical Heart Research, Oslo, Norway.

Induction of colorectal carcinogenesis in the C57BL/6J and A/J mouse strains with a reduced DSS dose in the AOM/DSS model

Background

Colorectal cancer (CRC) is one of the most frequently diagnosed cancers worldwide and thus mouse models of CRC are of significant value to study the pathogenesis. The Azoxymethane/Dextran sulfate sodium (AOM/DSS) model is a widely used, robust initiation-promotion model for chemical induction of colitis-associated CRC in rodents. However, the dosage of chemicals, treatment regimens and outcome measures vary greatly among studies employing this model. Thus, the aim of this study was to examine an AOM/DSS model involving a reduced (1%) dose of DSS for induction of carcinogenesis in A/J and C57BL/6J (B6) mice.

Results

We show that colonic preneoplastic lesions can be reliably detected in A/J and B6 mice by use of a AOM/DSS model involving a single injection of 10 mg/kg AOM followed by three 7-day cycles of a low-dose (1%) DSS administration. Supporting existing evidence of A/J mice exhibiting higher susceptibility to AOM than B6 mice, our AOM/DSS-treated A/J mice developed the highest number of large colonic lesions. Clinical symptoms in both strains subjected to the AOM/DSS treatment did not persist in-between treatment cycles, demonstrating that the animals tolerated the treatment well.

Conclusions

Our findings suggest that a reduced dose of DSS in the AOM/DSS model can be considered in future studies of early phase colorectal carcinogenesis in the A/J and B6 mouse strains using preneoplastic lesions as an outcome measure, and that such regimen may reduce the risk of early trial terminations to accommodate human endpoints. Overall, our data emphasize the importance of devoting attention towards choice of protocol, outcome measures and mouse strain in studies of CRC in mice according to the study purpose.

Supplementary Information

The online version contains supplementary material available at 10.1186/s42826-021-00096-y.

A Model System for Feralizing Laboratory Mice in Large Farmyard-Like Pens

Laboratory mice are typically housed under extremely clean laboratory conditions, far removed from the natural lifestyle of a free-living mouse. There is a risk that this isolation from real-life conditions may lead to poor translatability and misinterpretation of results. We and others have shown that feral mice as well as laboratory mice exposed to naturalistic environments harbor a more diverse gut microbiota and display an activated immunological phenotype compared to hygienic laboratory mice. We here describe a naturalistic indoors housing system for mice, representing a farmyard-type habitat typical for house mice. Large open pens were installed with soil and domestic animal feces, creating a highly diverse microbial environment and providing space and complexity allowing for natural behavior. Laboratory C57BL/6 mice were co-housed in this system together with wild-caught feral mice, included as a source of murine microbionts. We found that mice feralized in this manner displayed a gut microbiota structure similar to their feral cohabitants, such as higher relative content of Firmicutes and enrichment of Proteobacteria. Furthermore, the immunophenotype of feralized mice approached that of feral mice, with elevated levels of memory T-cells and late-stage NK cells compared to laboratory-housed control mice, indicating antigenic experience and immune training. The dietary elements presented in the mouse pens could only moderately explain changes in microbial colonization, and none of the immunological changes. In conclusion, this system enables various types of studies using genetically controlled mice on the background of adaptation to a high diversity microbial environment and a lifestyle natural for the species.

Naturalizing laboratory mice by housing in a farmyard-type habitat confers protection against colorectal carcinogenesis

Living in a farm environment in proximity to animals is associated with reduced risk of developing allergies and asthma, and has been suggested to protect against other diseases, such as inflammatory bowel disease and cancer. Despite epidemiological evidence, experimental disease models that recapitulate such environments are needed to understand the underlying mechanisms. In this study, we show that feralizing conventional inbred mice by continuous exposure to a livestock farmyard-type environment conferred protection toward colorectal carcinogenesis. Two independent experimental approaches for colorectal cancer induction were used; spontaneous (Apc Min/+ mice on an A/J background) or chemical (AOM/DSS). In contrast to conventionally reared laboratory mice, the feralized mouse gut microbiota structure remained stable and resistant to mutagen- and colitis-induced neoplasia. Moreover, the feralized mice exhibited signs of a more mature immunophenotype, indicated by increased expression of NK and T-cell maturation markers, and a more potent IFN-γ response to stimuli. In our study, hygienically born and raised mice subsequently feralized post-weaning were protected to a similar level as life-long exposed mice, although the greatest effect was seen upon neonatal exposure. Collectively, we show protective implications of a farmyard-type environment on colorectal cancer development and demonstrate the utility of a novel animal modeling approach that recapitulates realistic disease responses in a naturalized mammal.

The inflammasome signaling axis in thrombi from STEMI patients is related to degree of myocardial injury

Background

The NLRP3-inflammasome and the IL-6-pathways, i.e. the inflammasome signaling axis, seems to be central mechanisms in the inflammatory response related to myocardial reperfusion injury after revascularization. The beneficial results shown by treating MI-patients with canakunimab, an antibody blocking IL1-β, in the CANTOS trial*, and by treatment of NSTEMI patients with the IL6-receptor antagonist tocilizumab**, are looked upon as proof of concept for inflammasome inhibition.

Purpose

To study whether genes encoding inflammasome-related proteins are present in coronary thrombi and in circulating cells from STEMI patients, and whether these are related to the degree of myocardial injury as measured by troponin T, and time from symptoms to PCI.

Methods

Intracoronary thrombi were aspirated from 33 patients with STEMI treated with primary PCI. The thrombi were snap-frozen in RNA-later solution for gene expression analyses. Peripheral blood samples with Pax-gene tubes were drawn at end of the PCI-procedure. mRNA of NLRP3, caspase1, IL1-β, IL18, IL6, IL6-receptor (IL6-R) and gp130 were isolated from the thrombi and leukocytes in peripheral blood, and relatively quantified by RT PCR. Peak troponin was collected from clinical records.

Results

Genes coding for the 7 different markers were present in 76–100% of the thrombi. The expression of NLRP3 in thrombi significantly correlated to peak troponin T (r=0.468, p=0.024). Dividing peak troponin T values into quartiles, the median value of NLRP3 mRNA in Q4 was 2.0-fold higher compared to Q1–3 (p=0.012). Peak troponin T also correlated with the expression in circulating leukocytes of NLRP3 (r=0.420, p=0.0149) and IL1-β (r=0.394, p=0.023), and borderline to caspase1 (r=0.321, p=0.069) and IL18 (r=0.310, p=0.079).

IL6-R expression in thrombi correlated significantly to peak troponin T (r=0.434, p=0.019), with a 2.5-fold higher median level in Q4 vs Q1–3 of troponin T (p=0.017). gp130 expression in thrombi correlated inversely with peak troponin T (r=−0.398, p=0.050), as did IL6-R expression in circulating leukocytes (r=−0.421, p=0.015). There were no significant correlations between genes expressed in the thrombi and time from symptom to PCI (median 152 minutes), whereas genes for IL6 in circulating leukocytes correlated inversely (r=−0.385, p=0.027).

Conclusion

The inflammasome signaling pathway was actively regulated in coronary thrombi and in circulating leukocytes from patients with STEMI. Genes encoding NLRP3 and IL6-R were increasingly expressed in thrombi from patients with increased myocardial damage, measured by troponin T, supporting the beneficial effects of medically targeting this pathway.

Funding Acknowledgement

Type of funding source: Private grant(s) and/or Sponsorship. Main funding source(s): Stein Erik Hagens Foundation for Clinical Heart Research

Biomarkers in patients with cryptogenic stroke/TIA and subclinical atrial fibrillation

Background

A large proportion of patients with cryptogenic stroke or transitory ischemic attack (TIA) have underlying subclinical atrial fibrillation (SCAF) detected on follow up. It is not clear whether SCAF is the underlying primary entity in the pathogenesis of stroke in these patients, or merely a marker of atrial myopathy associated with left atrial remodeling, fibrosis and inflammation.

Purpose

As a hypothesis generating study, we investigated a panel of selected biomarkers involved in fibrosis, inflammation, and thrombosis: growth differentiation factor 15 (GDF-15), transforming growth factor b (TGFb), galectin-3, soluble suppressor of tumorgenicity2 (sST2), von Willebrand factor (vWF), Tissue metalloprotease1 (TIMP1), Matrix metalloprotease9 (MMP9), Emmprin, Interleukin6 (IL6), C-reactive protein (CRP), Tissue factor (TF), Plasminogen activator inhibitor (PAI1), and their relation to the occurrence of SCAF during follow-up in patients after cryptogenic stroke or TIA. We hypothized that biomarker levels were increased in patients with subclinical AF.

Methods

236 patients, median age 71 years (range 21–94) of which 38% were women, with their first cryptogenic stroke or TIA were included 2–4 days after the index event and followed with an Implantable Cardiac Rhythm Monitor for &gt;1 year. Echocardiography and blood sampling were performed at inclusion. ELISA methods were used.

Results

SCAF occurred in 84 patients (36%). Only GDF-15 was significantly increased in AF- vs no-AF patients: 1010 pg/mL (inter quartile range: 814–1416) vs 860 pg/mL (inter quartile range: 622–1197) (p=0.018), and correlated with the number of premature atrial contractions (PAC)/24h (by Holter ECG during index hospitalization) (rs=0.314, p&lt;0.001) and AF-burden during follow-up (rs=0.149, p=0.022). Furthermore, there was a significant trend across quartiles of GDF-15 for having AF, and patients in the three highest quartiles (Q2–4) compared with Q1 had an odd ratio of having AF of 2.16 (95% CI 1.10–4.25), adjusted for sex and body mass index. The significance, however, was lost when adjusting for age, which correlated significantly to GDF-15 (rs=0.283; p&lt;0.001). ROC curve analyses showed an AUC of 0.593 (0.52–0.68) for GDF-15 compared to 0.617 (0.54–0.69) for age. GDF-15 was also associated with co-morbidities such as hypertension (p&lt;0.001), diabetes (p&lt;0.001), and vascular disease (p&lt;0.001).

Conclusion

In patients with a cryptogenic stroke or TIA experiencing SCAF during follow up, only levels of GDF-15 were elevated and correlated with PAC/24h and AF-burden. However, GDF-15 was highly related to age and co-morbidities and did not add significantly to the prediction of AF in a multivariate analysis.

Funding Acknowledgement

Type of funding source: Foundation. Main funding source(s): Stiftelsen Dam, Norwegian Atrial Fibrillation Research Network

γδ T cells compose a developmentally regulated intrauterine population and protect against vaginal candidiasis

This most comprehensive analysis to date of γδ T cells in the murine uterus reveals them to compose a unique local T-cell compartment. Consistent with earlier reports, most cells expressed a canonical Vγ6Vδ1 TCR, and produced interleukin (IL)-17A upon stimulation. Nonetheless, contrasting with earlier reports, uterine γδ T cells were not obviously intraepithelial, being more akin to sub-epithelial Vγ6Vδ1+ T cells at several other anatomical sites. By contrast to other tissues however, the uterine compartment also included non-Vγ6+, IFN-γ-producing cells; was strikingly enriched in young mice; expressed genes hitherto associated with the uterus, including the progesterone receptor; and did not require microbes for development and/or maintenance. This notwithstanding, γδ T-cell deficiency severely impaired resistance to reproductive tract infection by Candida albicans, associated with decreased responses of IL-17-dependent neutrophils. These findings emphasise tissue-specific complexities of different mucosal γδ cell compartments, and their evident importance in lymphoid stress-surveillance against barrier infection.

Molecular modelling, synthesis, and biological evaluations of a 3,5-disubstituted isoxazole fatty acid analogue as a PPARα-selective agonist

The peroxisome proliferator activated receptors (PPARs) are important drug targets in treatment of metabolic and inflammatory disorders. Fibrates, acting as PPARα agonists, have been widely used lipid-lowering agents for decades. However, the currently available PPARα targeting agents show low subtype-specificity and consequently a search for more potent agonists have emerged. In this study, previously isolated oxohexadecenoic acids from the marine algae Chaetoceros karianus were used to design a PPARα-specific analogue. Herein we report the design, synthesis, molecular modelling studies and biological evaluations of the novel 3,5-disubstituted isoxazole analogue 6-(5-heptyl-1,2-oxazol-3-yl)hexanoic acid (1), named ADAM. ADAM shows a clear receptor preference and significant dose-dependent activation of PPARα (EC₅₀ = 47 µM) through its ligand-binding domain (LBD). Moreover, ADAM induces expression of important PPARα target genes, such as CPT1A, in the Huh7 cell line and primary mouse hepatocytes. In addition, ADAM exhibits a moderate ability to regulate PPARγ target genes and drive adipogenesis. Molecular modelling studies indicated that ADAM docks its carboxyl group into opposite ends of the PPARα and -γ LBD. ADAM interacts with the receptor-activating polar network of amino acids (Tyr501, His447 and Ser317) in PPARα, but not in PPARγ LBD. This may explain the lack of PPARγ agonism, and argues for a PPARα-dependent adipogenic function. Such compounds are of interest towards developing new lipid-lowering remedies.

Prolonged Thromboprophylaxis Following Hip Replacement Surgery – Results of a Double-blind, Prospective, Randomised, Placebo-controlled Study with Dalteparin (Fragmin®)

Discontinuation of thromboprophylaxis a few days after surgery may unmask delayed hypercoagulability and contribute to late formation of deep venous thrombosis (DVT). To investigate whether thromboprophylaxis should be prolonged beyond the hospital stay, a prospective, double-blind randomised study was conducted in 308 patients. All patients received initial thromboprophylaxis with dalteparin, dextran and graded elastic stockings. On day 7, patients were randomised to receive dalteparin (Fragmin®) 5000IU once daily, or placebo, for 4 weeks. All patients were subjected to bilateral venography, perfusion ventilation scintigraphy and chest X-ray on days 7 and 35. Patients with venographically verified proximal DVT on day 7 were withdrawn from the randomised study to receive anticoagulant treatment. The overall prevalence of DVT on day 7 was 15.9%. On day 35, the prevalence of DVT was 31.7% in placebo-treated patients compared with 19.3% in dalteparin-treated patients (p = 0.034). The incidence of DVT from day 7 to day 35 was 25.8% in the placebo-treated group versus 11.8% in the dalteparin-treated group (p = 0.017). The incidence of symptomatic pulmonary embolism (PE) from day 7 to day 35 was 2.8% in the placebo-treated group compared with zero in the dalteparin-treated group. This included one patient who died from PE. No patients experienced serious complications related to the injections of dalteparin or placebo. This study shows that prolonged thromboprophylaxis with dalteparin, 5000 IU, once daily for 35 days significantly reduces the frequency of DVT and should be recommended for 5 weeks after hip replacement surgery.

Effects of Gemfibrozil on Lipids and Haemostasis after Myocardial Infarction

The effects of gemfibrozil on haemostatic variables were studied in 43 survivors of myocardial infarction with serum triglycerides (TG) ≥2 mmol/1 2 weeks prior to randomization. The study was double-blind, placebo-controlled and stratified for chronic betablockade. Twenty-two individuals were given gemfibrozil 600 mg twice daily and 21 individuals received matching placebo. After 8 weeks the TG level was unchanged in the placebo group, whereas a 44% reduction was noted in the gemfibrozil group (p <0.0001). Fibrinogen increased in both groups, while bleeding time and platelet count were unchanged. Clotting factor VH-phospholipid complex decreased in both groups, but the change was more marked and attained statistical significance only in the gemfibrozil group (60% reduction, p <0.01). By DDAVP-stimulated D-Dimer agglutination test 8 in 21 patients in the placebo group (38%) still had reduced fibrinolytic capacity versus none in the gemfibrozil group (p = 0.001). Thus, in this study, gemfibrozil improved reduced fibrinolytic capacity and may have reduced hypercoagulability by lowering the clotting factor VH-phospholipid complex.

The Effect of Fibrinogen Degradation Products on Plasmin Activity

Purified fibrinogen degradation products Y, D or E were not found to exert antiplasmin activity as measured by the clot lysis time.

Spontaneous inactivation of plasmin was observed during incubation at 37° C. This inactivation was partly prevented by the presence of fibrinogen degradation products, as well as by other proteins.

Galectin-3, a marker of cardiac remodeling, is inversely related to serum levels of marine omega-3 fatty acids. A cross-sectional study

OBJECTIVE

Marine polyunsaturated n-3 fatty acids (n-3 PUFA) may have cardioprotective effects and beneficial influence on the fibrotic process. We evaluated the associations between serum marine n-3 PUFA and selected biomarkers of fibrosis and cardiac remodeling in elderly patients with acute myocardial infarction.

SETTING

From the ongoing OMega-3 fatty acids in Elderly patients with Myocardial Infarction (OMEMI) trial, 299 patients were investigated. Soluble ST2 (sST2), Galectin-3 (Gal-3) and the serum content of major marine n-3 and n-6 PUFA were analyzed 2-8 weeks after the index acute myocardial infarction.

RESULTS

Gal-3 was inversely correlated to eicosapentaenoic acid (r = -.120, p = .039) and docosahexaenoic acid (r = -.125, p = .031) and positively correlated to the n-6/n-3 ratio (r = .131, p = .023). Gal-3 levels were significantly higher in diabetics vs non-diabetics (12.00 vs 9.61 ng/mL, p = .007) and in patients with NYHA class ≥III for dyspnea at inclusion (11.33 vs 9.75 ng/mL, p = .006).

CONCLUSIONS

The associations between the marine n-3 PUFA and levels of Gal-3 indicate beneficial effects of n-3 PUFA on cardiac remodeling in an elderly population with acute myocardial infarction.

Cigarette smoking represses expression of cytokine IL-12 and its regulator miR-21-An observational study in patients with coronary artery disease

RATIONALE

The heterodimer IL-12 is an inducer of Th1 responses and stimulates INFƴ production. Micro-RNA-21 (miR-21) is described as a key regulator of the pro-inflammatory response and has IL-12p35 mRNA as one of its main targets. The IL-12p40 1188A/C genetic variant located in 3'untranslated region (UTR), thus environmentally exposed, has further been reported to modify IL-12 levels. We have previously reported on the lowering effect of cigarette smoke on circulating IL-12 in patients with coronary artery disease (CAD).

OBJECTIVES

To explore if cigarette smoking affects IL-12p35, IL-12p40, INFƴ and miR-21 gene-expression and further modulates any effect of the IL-12p40 polymorphism on circulating IL-12 levels.

METHODS AND RESULTS

The IL-12p40 1188A/C polymorphism was analyzed in 1001 stable CAD patients, of which 330 subjects were included for IL-12p35, IL-12p40 and INFƴ gene-expression analyses in circulating leukocytes and 200 were further selected for plasma miR-21 analysis. Smoking associated with lower expression of miR-21 and its target IL-12p35 mRNA (adjusted p<0.05, both) whereas the influence on INFƴ expression tended to be high-dose reliant (p = 0.057). The IL-12p40 CC genotype associated with elevated circulating IL-12 levels, however, when stratified according to smoking, only in the non-smoking group (adjusted p < 0.05). Although the markers were mainly downregulated in current smokers, their inter-correlations were potentiated.

CONCLUSION

Smoking associated with reduced miR-21 gene-repression and the results can therefore not explain the previously observed reduction in circulating IL-12. Smoking attenuated the IL-12 pro-inflammatory axis in which the investigated IL-12p40 genetic variant may have different clinical impact in smokers vs non-smokers.

Markers of thrombin generation are associated with myocardial necrosis and left ventricular impairment in patients with ST-elevation myocardial infarction

Introduction

Platelet activation, thrombin generation and fibrin formation play important roles in intracoronary thrombus formation, which may lead to acute myocardial infarction.

We investigated whether the prothrombotic markers D-dimer, pro-thrombin fragment 1 + 2 (F1 + 2) and endogenous thrombin potential (ETP) are associated with myocardial necrosis assessed by Troponin T (TnT), and left ventricular impairment assessed by left ventricular ejection fraction (LVEF) and N-terminal pro b-type natriuretic peptide (NT-proBNP).

Materials/Methods

Patients (n = 987) with ST-elevation mycardial infarction (STEMI) were included. Blood samples were drawn at a median time of 24 h after onset of symptoms.

Results

Statistically significant correlations were found between both peak TnT and D-dimer (p < 0.001) and F1 + 2 (p < 0.001), and between NT-proBNP and D-dimer (p = 0.001) and F1 + 2 (p < 0.001). When dividing TnT and NT-proBNP levels into quartiles there were significant trends for increased levels of both markers across quartiles (all p < 0.001) D-dimer remained significantly associated with NT-proBNP after adjustments for covariates (p = 0.001) whereas the association between NTproBNP and F1 + 2 was no longer statistically significant (p = 0.324).

A significant inverse correlation was found between LVEF and D-dimer (p < 0.001) and F1 + 2 (p = 0.013). When dichotomizing LVEF levels at 40 %, we observed significantly higher levels of both D-dimer (p < 0.001) and F1 + 2 (p = 0.016) in the group with low EF (n = 147).

Summary/conclusion

In our cohort of STEMI patients we demonstrated that levels of D-dimer and F1 + 2 were significantly associated with myocardial necrosis as assessed by peak TnT. High levels of these coagulation markers in patients with low LVEF and high NTproBNP may indicate a hypercoagulable state in patients with impaired myocardial function.

A brief review on high on-aspirin residual platelet reactivity

Although aspirin is effective in secondary prevention in coronary heart disease, new thromboembolic events in patients on aspirin are frequently seen. In trials on aspirin-treated patients, platelet function tests have revealed large variability in platelet aggregation. This phenomenon has been named aspirin resistance, aspirin non-responsiveness or high-on-aspirin residual platelet reactivity. The mechanism of aspirin antiplatelet effect is due to the inhibition of cyclooxygenase-1 enzyme in platelets. In some trials, almost all patients on aspirin have a very low level of serum thromboxane B2, indicating that the measured platelet reactivity in aspirin-treated patients might be due to platelet activation via other pathways, such as ADP or thrombin. The prevalence of real aspirin resistance seems to be very low, and probably the term "high-on-aspirin residual platelet reactivity" should be preferred to describe this phenomenon.