Cardiac pressure overload exposes hidden anthracycline-induced cardiotoxicity: results from a preclinical large-animal trial

Aim

The purpose of this work is to elucidate if low cumulative doxorubicin doses has a differential cardiac impact in pigs with or without pre-existing LV pressure overload. Impact of interventions on LV anatomy, function and tissue composition was evaluated by serial cardiac magnetic resonance (CMR). At the end of the in vivo protocol, hearts were processed to evaluate differential molecular pathways in both groups.

Methods

A total of 95 pigs were included. 52 animals underwent supravalvular aortic banding to generate LV hypertrophy, while another did not. 4 months after banding (a time where LV hypertrophy is prominent), animals in both groups were randomized to receive intravenous doxorubicin (1 mg/kg once per week, for 5 weeks) or saline. Thus, 4 study groups (N=15–22 per group) comprised the study population (banding yes/no, doxorubicin yes/no). All individuals underwent to serial Cardiac Magnetic Resonance exams every month and were sacrificed fo ex vivo analysisat 4 months after doxorubicin injections. To discriminate between doxorubicin effect in banding/no banding groups but also the effect of banding in doxorubicin protocols, t-test was used for two-group comparisons after two-way ANOVA test. Differences were considered statistically significant at p<0.05. Logrank test was performed to compare survival curves.

Results

Pigs receiving doxorubicin after cardiac pressure overload showed an increased mortality compared with the other groups (p=0.006). Only this group developed a progressive cardiotoxicity phenotype, characterized as a significant decline in cardiac function compared with control operated animals (49.7% ± 8.1 vs 79.6% ± 6.7, p<0.001), but also with non-operated pigs receiving the same anthracycline regime (vs 63.9% ± 4, p<0.001). Cardiac deterioration was based mainly on systolic dysfunction compared with control operated animals (38.2 ml indexed ± 3.5 vs 13.6±6.6, p=0.01) and non-operated pigs treated with doxorubicin (vs 26.6 ml indexed ± 6.6, p<0.001). In-vivo CMR tissue characterization revealed elevation on T2 relaxation times compared with Control animals (46.2 ms ± 3.5 vs 41.8±2.7, p=0.04) with no Extracellular Volume expansion. Ex-vivo histological analyses showed presence of intra-cardiomyocyte vacuolization in the Banding + DOXO group (p=0.01). Regarding mitochondrial phenotype, animals with Banding + DOXO exhibited a fragmented phenotype with extremely damaged mitochondria. Animals with only aortic banding exhibit increasing cardiac hyperkinesia and cardiac hypertrophy at the end of the study.

Conclusion(s)

We demonstrated that a very low dosage of doxorubicin is enough to exert cardiotoxicity in a pressure overload scenario. Characterized as a deterioration in cardiac function, myocardial edema, classical histological lesions and mitochondrial damage. Providing preclinical evidence that modest anthracycline protocols may be harmful for patients with cardiac comorbidities.

Funding Acknowledgement

Type of funding sources: Public grant(s) – EU funding. Main funding source(s): ERC MATRIX

A multidisciplinary approach of outdoor aeroallergen selection for skin prick testing in the geographical area of Greater Istanbul

Summary

Background. Aeroallergen selection for skin prick testing and the interpretation of results need to be in line with allergenic sources of a specific geographic area. Objective. To identify aeroallergens for a skin test panel for the specific geographical area of Istanbul in a multidisciplinary approach based on aerobiological parameters, cross-reactivity patterns and clinical symptoms. Methods. Aerobiological parameters, cross reactivity patterns and the European Standard Skin Prick Test Panel determined allergen selection. Atopic adult patients (n = 60) compiled a questionnaire and were skin prick tested with 34 aeroallergens. Aerobiological sampling followed the requirements of the European Aerobiology Society. Results were statistically analyzed. Results. 65% of patients had positive skin reactions. Sensitization to at least one grass allergen was 30%. Key grass allergens were timothy grass (Phleum pratense L.) 25.8% and Johnson grass (Sorghum halepense (L.) Pers.) 22.6%; correlations between grass-sensitizations were significant at p (minor) 0.01 and so was the correlation of Pooideae sensitization with symptoms and medication. Sensitization to at least one woody plant was 23%; to ash (Fraxinus excelsior L.) 8.1%; hazelnut (Corylus avellana L.), olive (Olea europaea L.) and mulberry (Morus alba L.) 6.5%; juniper (Juniperus ashei J.Buchholz) 4.8%. Correlations between Fagales allergen sensitizations were significant. Sensitization to at least one weed was 22%, sensitization to dock (Rumex crispus L.) 12.9%, ragweed (Ambrosia artemisiifolia L.), and mugwort (Artemisia vulgaris L.) 4.8%. Sensitization rates correlated significantly with the length of the Main Pollen Season. Conclusions. The European Standard Panel is suitable for the geographical area of Greater Istanbul, if it comprises Johnson grass and ash. Ragweed has become clinically relevant in this region. Mulberry and dock were exclusively associated to polysensitized individuals suggesting pan-allergen involvement.

P3108Microcirculation injury is involved in anthracycline-induced cardiac toxicity

Background/Introduction

Cardiotoxicity (CT) is a major concern for cancer patients receiving anthracyclines. While the effect of anthracyclines on cardiomyocytes is well established, its impact on myocardial microcirculation has not been characterized.

Purpose

To evaluate the effect of low and high cumulative doses of doxorubicin (doxo) on anatomical and functional vasculature status evaluated by serial invasive Coronary Flow Reserve (CFR) and Cardiac Magnetic Resonance (CMR)-based quantitative perfusion in a large animal model.

Methods

Large-white male pigs (n=15, 30 kg) were distributed in 2 doxo regimes: Group 1) high cumulative dose (5 biweekly intracoronary (i.c) injections of 0.45 mg/kg of doxo) followed-up until week 16 (a time when severe left ventricular systolic dysfunction is present) and then sacrificed (N=5); Group 2) low cumulative dose of doxo (3 biweekly i.c. doses) followed-up until week 16 and then sacrificed (N=5)). Group 3) pigs sacrificed at 6 weeks (2 weeks after third doxo dose), N=5. Invasive catheter-based CFR was evaluated after i.c papaverine (0.5 mg/kg) while CMR quantitative rest perfusion maps were obtained after intravenous injection of gadolinium. CFR and CMR were performed before doxo, and at 0, 2, 4, 6 and 16 weeks thereafter. Cardiac vessels were evaluated ex vivo with trichrome staining. Statistical analysis was performed using one-way ANOVA with multiple pairwise comparisons (vs. baseline) and Bonferroni corrected p-value.

Results

CFR and CMR-quantitative myocardial perfusion were non-significantly reduced after 3 doxo doses despite myocardial vasculature was overtly injured on histology at this timepoint. Animals receiving 5 doxo doses suffered a progressive deterioration of CFR and CMR-perfusion until week 16 (1.41±0.23 vs 3.71±0.94 at baseline [p=0.014] and 65.4±18.2 ml/100g/min vs 154.9±56.3 ml/100g/min at baseline [p=0.046], respectively). At 16 weeks histology revealed extensive microvascular damage with media layer involvement and perivascular fibrosis. Pigs receiving 3 doxo doses showed less pronounced CFR reduction on long-term follow-up (3.13±0.82 vs 3.69±1.57 at baseline [p>0.05] but overt CMR-perfusion reduction (138.3±11.9 vs 197.8±37.1 at baseline [p=0.045]). On histology, damage of vasculature including arterioles was evidenced to a lesser extent than in the high cumulative doxo dose group with mild microvascular disruption and smooth muscle vacuolization.

Conclusions

Doxorubicin results in a progressive damage of the myocardial microcirculation. Even low cumulative doxo doses (resulting in no overt left ventricular dysfunction) results in vascular damage. The microcirculation status may serve as an early marker of doxorubicin cardiotoxicity.

P4684Differential right ventricular adaptation patterns to chronic pressure overload

Background

Right ventricular (RV) dysfunction is the most important prognostic factor in chronic pulmonary hypertension (PH), but its underlying mechanisms are unknown. Clinical observation and prior experimental work suggest that RV pressure overload is not the only cause since the degree of RV adaptation varies with similar RV end-systolic pressures.

Purpose

Our aim was to characterize serial RV adaptation by cardiac magnetic resonance (CMR) in 3 different experimental large-animal models of increased afterload: a model of chronic postcapillary PH, a model of PH secondary to systemic-to-pulmonary shunt and a model of mechanical RV pressure overload (generated by pulmonary artery [PA] banding).

Methods

Four-week old piglets underwent pulmonary vein banding surgery to generate the chronic postcapillary PH model (n=20), aorto-pulmonary shunt (n=6), PA banding (n=7) or sham operation (n=7). They were followed up monthly with CMR and right heart catheterization (RHC). All procedures followed the “Principles of laboratory animal care”. Comparison of continuous variables among groups was performed with Mann-Whitney U test.

Results

Animals with either postcapillary PH or PH secondary to aorto-pulmonary shunt presented significant RV dilatation, hypertrophy and dysfunction that was maintained during follow-up (median RV end-systolic volume [RVESV]=32.6 ml/m2 for postcapillary PH and 32.6 ml/m2 for shunt vs. 16.1 ml/m2 in sham controls; median RV ejection fraction [RVEF]=61.5% for postcapillary PH and 60.5% for shunt vs. 69.6% in sham controls at the end of follow-up). Animals with PA banding also presented with significant RV dilatation and hypertrophy at the first month follow-up, but unlike all other groups, they developed reverse RV remodeling from the second month onwards and maintained normal RV volumes and RVEF values until the end of follow-up despite having severe RV hypertrophy (RV mass 22.6 g/m2 in PA banding vs. 16.1 g/m2 in controls at the 4th month follow-up; Figure).

CMR parameters (median values).

Conclusion

In PH there is a maladaptive RV hypertrophy that is not present in a model of progressive RV pressure overload without alterations of the pulmonary circulation. Increased RV pressure overload alone does not fully explain PH-associated RV dysfunction. Further research is needed to clarify the underlying mechanisms of adaptive and maladaptive hypertrophy in PH.

Acknowledgement/Funding

The CNIC is supported by the Ministerio de Ciencia, Innovaciόn y Universidades and the Pro CNIC Foundation, and is a Severo Ochoa Center of Excellence

P596Early markers of right ventricular involvement in experimental chronic postcapillary pulmonary hypertension

Background

In chronic pulmonary hypertension (PH), the main cause of death is right ventricular (RV) failure. However, the onset of RV dysfunction varies significantly among patients. Early recognition of RV maladaptation would be highly relevant.

Purpose

To identify cardiac magnetic resonance (CMR)-derived parameters affected in early stages of PH before the development of RV dysfunction.

Methods

Experimental chronic PH was generated by pulmonary vein banding in 76 pigs whereas 14 animals underwent sham operation. Animals were followed-up monthly with right heart catheterization (RHC) and immediate CMR for a maximum of 9 months. CMR exams included a T1-mapping sequence to quantify equilibrium-extracellular volume (ECV) at the RV insertion points. Pairs of RHC and CMR examinations were compared among controls and PH with normal RV ejection fraction (RVEF≥55%) or reduced (REVF<55%) using ANCOVA test with Bonferroni correction. All procedures followed the “Principles of laboratory animal care”.

Results

In the presence of PH confirmed by RHC and normal RVEF, the RV displays significant hypertrophy and increased myocardial native T1 and ECV, despite preserved ventricular dimensions and PA flow (Fig 1B). In advanced stages of the disease, RV-AP uncoupling and reduced PA pulsatility develop together with RV dilatation and failure (Fig 1C).

CMR parameters in sham and PH animals Sham controls (n=25 evaluations) PH with normal RVEF (n=155 evaluations) PH with low RVEF (n=70) RVEF (%) 62±5 61±4 47±8# RVEDV (mL/m2) 73±18 83±17 111±29# RVESV (mL/m2) 28±8 32±8 61±25# RV mass (g/m2) 17±4 23±5* 30±11# PA area (cm2/m2) 5.5±1.2 6.3±1.6 8.7±2.2# Native T1 anterior RVIP (ms) 983±75 1043±78* 1055±90# ECV anterior RVIP (%) 27±5 31±6* 36±7# Native T1 inferior RVIP (ms) 959±68 1022±71* 1032±99# ECV inferior RVIP (%) 25±5 31±6* 36±7# PA pulsatility (%) 29±6 27±7 21±3# Ea/Emax 40±16 47±11 97±65# RVEDV: RV end-diastolic volume; RVESV: RV end-systolic volume; RVIP: RV insertion point. *p<0.05 1 vs. 2; #1 vs. 3.

NativeT1: control, PH-normal RV, RV dysf

Conclusion

RV hypertrophy and ECV expansion are early mechanisms in RV adaptation to postcapillary PH, whereas ventricular and PA dilatation, RV-PA uncoupling and reduced pulsatility appear in more advanced stages concurring with systolic dysfunction.

Acknowledgement/Funding

The CNIC is supported by the Ministerio de Ciencia, Innovaciόn y Universidades and the Pro CNIC Foundation, and is a Severo Ochoa Center of Excellence

Airborne olive pollen counts are not representative of exposure to the major olive allergen Ole e 1

Pollen is routinely monitored, but it is unknown whether pollen counts represent allergen exposure. We therefore simultaneously determined olive pollen and Ole e 1 in ambient air in Córdoba, Spain, and Évora, Portugal, using Hirst-type traps for pollen and high-volume cascade impactors for allergen. Pollen from different days released 12-fold different amounts of Ole e 1 per pollen (both locations P < 0.001). Average allergen release from pollen (pollen potency) was much higher in Córdoba (3.9 pg Ole e 1/pollen) than in Évora (0.8 pg Ole e 1/pollen, P = 0.004). Indeed, yearly olive pollen counts in Córdoba were 2.4 times higher than in Évora, but Ole e 1 concentrations were 7.6 times higher. When modeling the origin of the pollen, >40% of Ole e 1 exposure in Évora was explained by high-potency pollen originating from the south of Spain. Thus, olive pollen can vary substantially in allergen release, even though they are morphologically identical.

Viral envelope glycoprotein processing by proprotein convertases

The proprotein convertases (PCs) are a family of nine mammalian enzymes that play key roles in the maintenance of cell homeostasis by activating or inactivating proteins via limited proteolysis under temporal and spatial control. A wide range of pathogens, including major human pathogenic viruses can hijack cellular PCs for their own purposes. In particular, productive infection with many enveloped viruses critically depends on the processing of their fusion-active viral envelope glycoproteins by cellular PCs. Based on their crucial role in virus-host interaction, PCs can be important determinants for viral pathogenesis and represent promising targets of therapeutic antiviral intervention. In the present review we will cover basic aspects and recent developments of PC-mediated maturation of viral envelope glycoproteins of selected medically important viruses. The molecular mechanisms underlying the recognition of PCs by viral glycoproteins will be described, including recent findings demonstrating differential PC-recognition of viral and cellular substrates. We will further discuss a possible scenario how viruses during co-evolution with their hosts adapted their glycoproteins to modulate the activity of cellular PCs for their own benefit and discuss the consequences for virus-host interaction and pathogenesis. Particular attention will be given to past and current efforts to evaluate cellular PCs as targets for antiviral therapeutic intervention, with emphasis on emerging highly pathogenic viruses for which no efficacious drugs or vaccines are currently available.

Projections of the effects of climate change on allergic asthma: the contribution of aerobiology

Climate change is unequivocal and represents a possible threat for patients affected by allergic conditions. It has already had an impact on living organisms, including plants and fungi with current scenarios projecting further effects by the end of the century. Over the last three decades, studies have shown changes in production, dispersion and allergen content of pollen and spores, which may be region- and species-specific. In addition, these changes may have been influenced by urban air pollutants interacting directly with pollen. Data suggest an increasing effect of aeroallergens on allergic patients over this period, which may also imply a greater likelihood of the development of an allergic respiratory disease in sensitized subjects and exacerbation of symptomatic patients. There are a number of limitations that make predictions uncertain, and further and specifically designed studies are needed to clarify current effects and future scenarios. We recommend: More stress on pollen/spore exposure in the diagnosis and treatment guidelines of respiratory and allergic diseases; collection of aerobiological data in a structured way at the European level; creation, promotion and support of multidisciplinary research teams in this area; lobbying the European Union and other funders to finance this research.

Pollen allergy in Cordoba city: frequency of sensitization and relation with antihistamine sales

The occurrence of symptoms in pollen allergy patients in urban areas may be affected by local environmental factors such as sources of pollution, natural and ornamental vegetation, local architecture impeding dispersion, etc. The aim of this study was to analyse the frequency of sensitization in pollen allergy patients and the relationship with antihistamine sales. For this study, a large number of clinical records, together with pharmaceutical and pollen data, were collected between 1999 and 2001 in the city of Córdoba, in the south of the Iberian Peninsula. Differences were observed in the symptoms suffered by pollen allergy patients in different areas of the city due to varying local emission of both biological and non-biological particles. Temporal distribution of symptoms over the three study years was influenced by meteorological factors, especially rainfall patterns; higher water supply to plants was associated with increased airborne pollen concentrations. Air pollution might be one of the main factors affecting the distribution of pollen allergy patients within the city. Recent years have seen a worsening of symptoms and increased sensitization to urban species such as plane-trees.

Correlation between pollen counts and symptoms in two different areas of the Iberian Peninsula: Cordoba (Spain) and Evora (Portugal)

This work was designed to analyse the symptoms of pollen allergy in two different cities of the Iberian Peninsula, Cordoba and Evora. Fifteen patients with pollinosis in Cordoba and twenty-seven in Evora were included in this study. Rhinitis symptoms scores were recorded in both cities in order to correlate these data with those of pollen counts. Linear regression analyses were performed in order to find out the contribution of different taxa to the sign of allergy symptoms in the allergenic population. Skin prick tests were also considered. A high and significant correlation was found for Poaceae (0.89), Olea (0.73) and Plantago (0.56) in Cordoba and Olea (0.53) in Evora. Results also suggest that the incidence of the different pollen types in allergy patients is higher in Cordoba than in Evora. A rural lifestyle in Evora that confers a better protection from environmental agents in addition to a less contaminated atmosphere could be the cause.

The use of a neural network to forecast daily grass pollen concentration in a Mediterranean region: the southern part of the Iberian Peninsula

BACKGROUND

Pollen allergy is a common disease causing hayfever in 15% of the population in Europe. Medical studies report that a prior knowledge of pollen content in the air can be useful in the management of pollen-related diseases.

OBJECTIVES

The aim of this work was to forecast daily Poaceae pollen concentrations in the air by using meteorological data and pollen counts from previous days as independent variables.

METHODS

Linear regression models and co-evolutive neural network models were used for this study. Pollen was monitored by a Hirst-type spore trap using standard techniques. The data were obtained from the Spanish Aerobiology Network database, University of Cordoba Monitoring Unit. The set of data includes a series of 20 years, from 1982 to 2001. A classification of the years according to their allergenic potential was made using a K-mean cluster analysis with pollen and meteorological parameters. Statistical analysis was applied to all the years of each class with the exception of the most recent year, which was used for model validation.

RESULTS

It was observed that cumulative variables and pollen values from previous days are the most important factors in the models. In general, neural network equations produce better results than linear regression equations.

CONCLUSION

Co-evolutive neural network models, which obtain the best forecasts (an almost 90% "good" classification), make it possible to predict daily airborne Poaceae pollen concentrations. This new system based on neural network models is a step toward the automation of the pollen forecast process.

Glutathione-S-Transferase M1 and codon 72 p53 polymorphisms in a northwestern Mediterranean population and their relation to lung cancer susceptibility

Several polymorphic genes have been reported to be possibly involved in modifying lung cancer risk in smokers. The gene GSTM1 is frequently deleted in human populations, and the null genotype has been reported to be a risk factor for developing lung carcinoma. A germline polymorphism of p53 with a single-base change at codon 72 that causes an amino acid replacement of arginine (Arg; CGC) by proline (PRO; CCC) has also been reported to be associated with cancer susceptibility in a Japanese population. Both polymorphisms were genotyped by PCR in a northwestern Mediterranean healthy population (n = 147) and in a group of lung cancer patients (n = 139). The results showed that the frequency of the GSTM1 null genotype was higher in the lung cancer patients compared to the controls [odds ratio (OR), 1.57; 95% confidence interval (CI), 0.99-2.51]. The histological subtypes most clearly modified were small cell carcinoma (OR, 1.89; CI, 0.97-3.65) and adenocarcinoma (OR, 1.93; CI, 0.90-4.14). The null GSTM1 genotype was more frequent among those cancer patients who were medium/ light smokers (< or = 50 pack-years) and in those who showed an onset of the disease at a more advanced age. The study of the p53 polymorphism in the healthy population showed allele frequencies of 0.79 (Arg) and 0.21 (Pro). The frequencies found in the lung cancer patients were statistically similar. Both polymorphisms were studied together, and the relative risk of the combination null GSTM1 and Pro/Pro or Arg/Pro genotypes was calculated taking the combination of GTSM1 + together with Arq/Arg as a baseline. The OR found (1.97; CI, 1.03-3.73) suggests that the Pro allele of the p53 germline polymorphism may slightly increase the risk fo the GSTM1 null genotype among smokers.