Heart transplantation and biomarkers: a review about their usefulness in clinical practice

Advanced heart failure (AdvHF) can only be treated definitively by heart transplantation (HTx), yet problems such right ventricle dysfunction (RVD), rejection, cardiac allograft vasculopathy (CAV), and primary graft dysfunction (PGD) are linked to a poor prognosis. As a result, numerous biomarkers have been investigated in an effort to identify and prevent certain diseases sooner. We looked at both established biomarkers, such as NT-proBNP, hs-troponins, and pro-inflammatory cytokines, and newer ones, such as extracellular vesicles (EVs), donor specific antibodies (DSA), gene expression profile (GEP), donor-derived cell free DNA (dd-cfDNA), microRNA (miRNA), and soluble suppression of tumorigenicity 2 (sST2). These biomarkers are typically linked to complications from HTX. We also highlight the relationships between each biomarker and one or more problems, as well as their applicability in routine clinical practice.

Evidence of mitochondrial alterations in primary cardiac stromal cells from arrhythmogenic cardiomyopathy hearts

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): This research was funded by the Department of Innovation, Research and University of the Autonomous Province of Bolzano-South Tyrol (Italy), and by the Joint Project Südtirol- FWF (Italy-Austria) for A.R., J.T., A.M., R.P..

Background

Arrhythmogenic cardiomyopathy (ACM) is a genetic disease associated with sudden cardiac death and fibro-fatty replacement of myocardium. Recently, it has been demonstrated that oxidized lipid contributes to cardiac adipogenesis and that ACM hearts are characterized by an increase in oxidative stress.

Purpose

As mitochondria are an important source of reactive oxygen species (ROS) within mammalian cells, the present work aims to evaluate if increased oxidative stress observed in ACM hearts is associated with altered mitochondrial function.

Methods

The oxidative stress marker 4HNE was investigated together with the cardiomyocyte marker cardiac Troponin T on paraffin embedded human ventricular samples and analyzed by confocal microscopy.

Human primary cardiac stromal cells (CStCs), obtained from either right ventricle biopsies of ACM patients or healthy cadaveric tissue donor (CTR), were used as cellular model as they are known for their contribution to adipogenesis in the ACM pathology. CStCs were cultured either in basal medium or adipogenic medium (ADIPO) in presence or absence of 500 nM of the ROS scavenger MitoTEMPO.

After 7 days of adipogenic differentiation, intracellular lipid droplets accumulation and mitochondrial superoxide levels were measured in CStCs by confocal microscopy using BODIPY 493/503 (0.5 µM) and MitoSOX Red (5 µM) dyes, respectively.

The oxidative phosphorylation (OXPHOS) and fatty acid oxidation (FAO) were also evaluated in CStCs by high resolution respirometry.

Results

4HNE staining was increased in heart tissues from ACM patients compared to CTRs and particularly evident in non-cardiomyocyte cells. In agreement, a higher MitoSOX fluorescence intensity was found in ACM-CStCs compared to CTR-CStCs in ADIPO medium, confirming higher ROS presence in patient cells. The treatment with MitoTEMPO was efficient in reducing ROS abundance, strongly suggesting mitochondrial origin. Lipid accumulation in ACM-CStCs was also prevented by MitoTEMPO treatment.

Preliminary evidence further indicates that mitochondrial respiratory capacity is increased in ACM-CStCs versus CTR-CStCs exposed to adipogenic medium for 7 days. However, transmission electron microscopy analysis and Western blot analysis of Mfn1/2, Opa1, Fis1 and Drp1 did not show an evident alteration neither in mitochondria ultrastructure nor in the expression of proteins regulating mitochondrial dynamics.

Conclusions

Our data support an alteration of mitochondrial activity in CStCs from ACM patients, apparently not linked to a modified network or morphology of mitochondria but associated with a higher ROS production.

A robotic system for real-time analysis of inhaled submicron and microparticles

Vitamin E acetate (VEA) has been strongly linked to outbreak of electronic cigarette (EC) or vaping product use-associated lung injury. How VEA leads to such an unexpected morbidity and mortality is currently unknown. To understand whether VEA impacts the disposition profile of inhaled particles, we created a biologically inspired robotic system that quantitatively analyzes submicron and microparticles generated from ECs in real-time while mimicking clinically relevant breathing and vaping topography exactly as happens in humans. We observed addition of even small quantities of VEA was sufficient to alter size distribution and significantly enhance total particles inhaled from ECs. Moreover, we demonstrated utility of our biomimetic robot for studying influence of nicotine and breathing profiles from obstructive and restrictive lung disorders. We anticipate our system will serve as a novel preclinical scientific research, decision-support tool when insight into toxicological impact of modifications in electronic nicotine delivery systems is desired.

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Vitamin E acetate (VEA) has been strongly linked to outbreak of EVALI

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A bio-inspired robot was created for real-time analysis of inhaled particles from ENDS

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VEA in e-liquid, even at small doses, was sufficient to enhance total inhaled particles

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This robotic system enables preclinical toxicity evaluation of ENDS and tobacco products

The importance of first and second ventilatory thresholds to define aerobic exercise intensity in cardiac patients and in healthy subjects: what is essential can be visible to the eyes

Funding Acknowledgements

Type of funding sources: None.

Background. Although structured exercise training is strongly recommended in cardiac patients, uncertainties exist about the methods for determining exercise intensity (EI) and their correspondence with effective EI obtained by ventilatory thresholds. We aimed to determine the first (VT1) and second ventilatory threshold (VT2) in cardiac patients, sedentary subjects and athletes comparing VT1 and VT2 with EI defined by recommendations.

Methods. We prospectively enrolled 350 subjects (mean age: 50.7 ± 12.9 years; 167 cardiac patients, 150 healthy sedentary subjects, 33 competitive endurance athletes). Each subject underwent ECG, echocardiography, and cardiopulmonary exercise testing. The percentages of peak VO2, peak heart rate (HR), and HR reserve were obtained at VT1 and VT2, and compared with EI definition proposed by the recommendations.

Results. VO2 at VT1 corresponded to high rather than moderate EI in 67.1% and in 79.6% of cardiac patients, applying the definition of moderate exercise by the previous recommendations and the 2020 guidelines, respectively. Most of cardiac patients had VO2 values at VT2 corresponding to very-high rather than high EI (59.9% and 50.3%, by previous recommendations and 2020 guidelines, respectively). A better correspondence between ventilatory-thresholds and recommended EI domains was observed in healthy subjects and in athletes (90% and 93.9%, respectively).

Conclusions. EI definition based on percentages of peak HR and peak VO2 may misclassify the effective EI and the discrepancy between the individually determined and the recommended EI is particularly relevant in cardiac patients. A ventilatory threshold-based rather than a range-based approach is advisable in order to define an appropriate level of EI.

Abstract Figure.

Intracranial hypertension and cryptococcal meningitis in a girl with AIDS

A girl with HIV infection acquired at birth by blood transfusion, was admitted at the age of 10 years for diplopia, vomiting, headache and papilledema. CT scan was negative. A lumbar puncture revealed clear CSF, protein 0.40 g/l, glucose 2 mmol/l, 5 mononuclear cells/mm3. The Indian ink preparation and the latex agglutination antigen test were positive for Cryptococcus n. Treatment with amphotericin B and flucytosine was started. After 10 days, since the in vitro susceptibility testing of the isolates showed resistence to both drugs, fluconazolo (400 mg/day) was started. Acetazolamide, furosemide and spironolactone were then added to the antifungal therapy for the persistence of severe intracranial hypertension. Diuretics were maintained for 10 weeks. The patient returned to school two and half months after the admission to the hospital. After 19 months, she is doing well and she is on maintenance of fluconazole (200 mg/day). We hypothesized that the increased intracranial pressure would be due to an impaired CSF reabsorption probably as a consequence of a direct cryptococcal infiltration of the villi.

Antibody responses to Haemophilus influenzae type b and Streptococcus pneumoniae vaccines in children with human immunodeficiency virus infection

Antibody responses to Haemophilus influenzae type b (Hib) conjugate (ActHIB; Pasteur Merieux) and pneumococcal (Pneumovax II; Morson) vaccines were measured in 56 infected children (VI) and 44 uninfected children (U) older than 18 months of age, born to human immunodeficiency virus-positive mothers. Preimmunization, 21% U and 20% VI had protective concentrations of anti-Hib polysaccharide antibodies. Postimmunization, 100% U and 86% VI achieved protective titers (P = 0.008). The geometric mean increase in anti-Hib polysaccharide antibody was 7.6 (95% confidence interval, 3.5 to 16.3; P = 0.0001) times higher in U than in VI children after adjusting for age and ethnicity. Sixty-one percent U compared to 54% VI showed a 2-fold increase in antibody levels to at least one of the four pneumococcal vaccine serotypes (3, 6, 19, 23) measured (P = 0.4). For both vaccines there was a significant trend toward poorer responses in children with acquired immunodeficiency syndrome but no correlation with age adjusted CD4 counts. These data suggest that human immunodeficiency virus-infected children should be immunized with these polysaccharide vaccines early in the course of their disease.

Cerebrospinal fluid analysis in HIV-1-infected children: immunological and virological findings before and after AZT therapy

Immunological and viral studies were conducted on cerebrospinal fluid from 31 HIV-1-infected children, of whom 23 were neurologically asymptomatic and 8 had progressive encephalopathy. After AZT treatment, a second cerebrospinal fluid specimen was obtained from 15 children, 11 of whom were neurologically asymptomatic and 4 had progressive encephalopathy. Virus isolation and p24Ag detection were more frequent in children with progressive encephalopathy than in asymptomatic children (66% versus 12%) and were inversely correlated with intrathecal HIV-1-antibody detection (anti-gag AB: 25% versus 70%). High concentrations of interleukin-1 beta (IL-1 beta) and IL-6 were found in children with progressive encephalopathy (50% and 37%, respectively), but low levels were also detected in some asymptomatic children (13% and 9%, respectively). Tumour necrosis factor-alpha (TNF alpha) was not found. AZT treatment induced disappearance of p24Ag in cerebrospinal fluid, as well as a marked reduction in cytokine levels. Cytokine determination may be useful in monitoring AZT treatment in children with progressive encephalopathy.

The use of antibiotics in the treatment and prevention of infection in HIV-infected children

Children with HIV infection have an unusual susceptibility to bacterial infection, related to several immune abnormalities. Selection of initial antibiotic therapy must be individualized in these children. Patients with community-acquired disease are most likely to have infection by polysaccharide-encapsulated bacterial organism, most commonly Streptococcus pneumoniae and less frequently by Haemophilus influenzae type b. If it is possible to treat the patients at home, the use of amoxicillin-clavulanic acid might be appropriate. Other authors propose management with parenteral ceftriaxone because of the better compliance and the malabsorption. In hospitalized patients, concern for Gram-negative enteric pathogens other than polysaccharide-encapsulated organisms requires initial therapy with a third-generation cephalosporine in combination with an aminoglycoside. Trimethoprim-sulfamethizole is the most common drug used in HIV-infected children because it is recommended for the initial therapy and for prophylaxis of pneumocystis carinii pneumonia, which occurs in as many as 42% of these children.