Small nucleolar RNA SNORD3A: a potential new biomarker and molecular player in heart failure

Background

Despite optimal therapy, heart failure (HF) remains a relentless and deadly disease. Given the relative inaccessibility of myocardial human tissues, identification of circulating biomarkers mirroring myocardial pathological signaling pathways, especially in peripheral blood mononuclear cells (PBMC) is expected to be extremely relevant. Small Nucleolar RNAs (snoRNAs) have been shown to play important roles in various cellular physiological processes. However, the connection between snoRNAs and pathological dysfunction in the heart or peripheral blood mononuclear cells (PBMC) is still poorly understood.

Purpose

To identify novel circulating PBMC biomarkers linked to myocardial dysfunction and HF.

Methods

Myocardial left ventricle (LV) samples and PBMC were obtained from patients affected by ischemic HF (HF, n=13) undergoing heart transplantation and control donors (CD, n=7) and analyzed by RNA sequencing analysis (RNASeq). SNORD3A expression levels in the different groups were evaluated by quantitative real-time PCR. HF was induced in 8-week-old wild type C57BL/6 mice by transverse aortic constriction (TAC). Sham-operated mice (sham) were used as controls. After twelve-week-TAC (12w) or sham operation, mice were anesthetized, cardiac function was analyzed by echocardiography, and cardiac/PBMC samples were collected after sacrifice. In order to test the role of SNORD3A in cardiomyocyte hypoxia, H9C2 cardiomyoblasts were transfected with SNORD3A-targeted antisense oligonucleotides (ASO) and cell survival was analyzed by cleaved caspase-3 and PARP1 immunoblotting.

Results

RnaSeq analysis identified a small set of genes differentially expressed in the heart and PBMC from HF patients. Among these, SNORD3A was up-regulated in cardiac and PBMC samples from HF patients compared to CD (Figure 1A-B). Similarly, in murine HF induced by 12w TAC, SNORD3A levels were increased by rtPCR, both in the heart and PBMC (Figure 1C-D). SNORD3A expression levels were also significantly increased in H9C2 cells exposed to in vitro hypoxia (Figure 1E). Interestingly, H9C2 transfection with SNORD3A-specific ASO significantly reduced hypoxia-induced SNORD3A upregulation and reduced hypoxia-induced cell death (Figure 1F-G).

Conclusions

In this study, we identify SNORD3A as a novel possible biomarker in human HF, similarly up-regulated in the heart and PBMC, induced by hypoxia in vitro and modulating cell survival.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): STAR GRANT Figure 1

Partial loss of Akap1 promotes cardiac dysfunction, gut barrier dysfunction and alterations of gut microbiota composition during aging

Background

Mitochondrial A-kinase anchoring proteins (mitoAKAP) encoded by the Akap1 gene are crucially involved in multiple cellular processes, including cardiomyocyte survival and function. Whether mitoAKAP levels play a role in aging and gut microbiota composition is currently unknown.

Purpose

The aim of this study was to highlight the complex interplay between cardiac dysfunction, gut barrier integrity, gut microbiota composition and aging in young (6-month-old, 6m) and old (24-month-old, 24m) wild type (wt) and Akap1 heterozygous mice (Akap1+/−).

Methods

Cardiac function was analyzed by echocardiography in 6m and 24m wt and Akap1+/− mice. Gut microbial DNA was extracted and gut microbiota composition was analyzed by Illumina Mi-Seq analysis. Bioinformatics analysis was carried out to identify major intestinal populations. Alpha diversity within each sample was determined, and then analyzed according to genotype and age; then, inter-sample diversity was determined. For each dataset, we used UniFrac to calculate the differences between microbial communities based on phylogenetic distance between taxa sets in a phylogenetic tree. Bioinformatics analyses were performed using the analysis of similarities (ANOSIM). To evaluate the role of mitoAKAPs in intestinal permeability, we analyzed intestinal junction proteins expression levels in colon samples of all groups. Variance analysis was performed to determine significance among the groups.

Results

Partial loss of Akap1 accelerated the progression of cardiac dysfunction in 24m mice, as demonstrated by a significantly lower % fractional shortening (%FS) compared to 24m wt mice (%FS, wt 6m: 60±3; Akap1−/+ 6m: 58±5; wt 24m: 49±6*; Akap1−/+ 24m: 39±12*§; *p<0.05 vs. wt 6m; §p<0.05 vs. wt 24m). In 24m Akap1+/− mice, aging was associated to enhanced colon permeability, as shown by reduced levels of Ocludins and Tight Junction Proteins 1 mRNA expression. A principal coordinate analysis of fecal samples based on their unweighted UniFrac distances revealed that samples from Akap1+/− 24m mice cluster apart from wt 24m samples, suggesting that Akap1+/− 24m mice exhibit a different assortment of microbial communities. This observation was supported by ANOSIM R statistic that revealed significant differences in gut microbiota composition between wt and Akap1+/− 24m mice (ANOSIM R=0.475, P=0.023), We analyzed the differences in abundance of all 2,042 Operational Taxonomic Units (OTUs) between age-matched wt and Akap1+/−. We identified 10 OTUs differently represented in wt and Akap1+/− 6m mice, while a bigger set of bacterial OTUs (19) were different between wt and Akap1+/− 24m mice. Consistent with previous results in patients with heart failure, we identified Clostridiales, Blautia producta and R. Torques among differently regulated species.

Conclusion

Partial Akap1 deletion plays an important role in the progression toward HF and modulates colon permeability and gut microbiota composition during aging.

Funding Acknowledgement

Type of funding sources: Public Institution(s). Main funding source(s): Programma STAR Grant by Federico II University and Compagnia San Paolo

Transverse aortic constriction impairs intestinal barrier integrity, promotes inflammation and alterations in gut microbiota composition

Background

Microbiota composition plays an important role in the pathophysiology of heart failure (HF). Reduced cardiac output can disrupt intestinal barrier function and promote systemic inflammation through bacterial translocation. Several gut and cardiac pathological conditions are reciprocally linked at multiple levels and through different, still largely undefined mechanisms.

Purpose

We analyzed the effects of Transverse aortic constriction (TAC) on aortic pressures, gut barrier integrity, systemic inflammation and gut microbiota composition.

Methods

TAC was induced in C57BL6 mice of either sex. Sham-operated (Sham) mice were used as controls. After one-week (1w) and four weeks (4w), mice have been anesthetized, cardiac function and abdominal aortic blood flow were analyzed. Colon, serum and feces samples were collected after sacrifice. Intestinal barrier integrity was evaluated in colon samples by Tight junction protein ZO-1 (Tjp1) and Occludin (Ocln) mRNA analysis. Circulating levels of Tumor Necrosis Factor-alpha (TNF-alpha), Lipopolysaccharide (LPS), Interleukin-10 and Interleukin-1 were measured. Microbial DNA was extracted from feces samples and gut microbiota composition was evaluated by Illumina Mi-Seq analysis.

Results

TAC induced left ventricular hypertrophy and systolic dysfunction. Abdominal aortic blood flow was significantly reduced in TAC mice compared to sham (Figure 1A). Decreased intestinal perfusion in TAC mice was associated to a prompt and strong weakening of intestinal barrier integrity and long-lasting decrease of colonic anti-inflammatory cytokine levels, as shown by reduced mRNA expression of interleukin-10 (IL-10) and Occludin (Ocln) (Figure 1B). Serum levels of lipopolysaccharide (LPS) were increased after TAC surgery and significant increases of circulating proinflammatory cytokines tumor necrosis factor-a (TNF-a) were detected in TAC mice (Figure 1C). High-resolution approach was used to obtain bacterial species assignment of key genera with significant differences among groups. After TAC, significant increases of Bifidobacterium, Lactobacillus and Turicibacter, whereas the genus Oscillospira was significantly less (Figure 1D). Butyrate-producing bacteria are considered relevant colonizers of the gastrointestinal tract being butyrate important in anti-inflammation and maintaining intestinal barrier integrity. Oscillospira genus members have been described as butyrate producers. Notably, in old patients with heart failure and in animal models of hypertension, increase in lactate-producing Lactobacillus was found.

Conclusions

These data indicate a remodeling of specific bacterial species abundance within identified key genera starting soon after TAC, designating a clear effect of the treatment on microbiota profiles and, possibly, on microbiota functionality. Gut dysbiosis may represent an element to be considered in the development or progression of cardiac dysfunction.

Figure 1

Funding Acknowledgement

Type of funding source: Other. Main funding source(s): CP was supported by Ministero dell'Istruzione, Università e Ricerca Scientifica grant (2015583WMX) and Programma STAR grant by Federico II University and Compagnia di San Paolo. RP was supported by a research grant provided by the Cardiopath PhD program. LC was supported by 2018-2019 Postdoctoral Fellowship Grants provided by Fondazione Umberto Veronesi.

Ataxia-telangiectasia mutated protein protects cardiac cells from stress by rewiring glucose metabolism

Introduction

Pressure overload-induced cardiac hypertrophy is associated with increased reactive oxygen species (ROS), inducing DNA damage and activating the protein kinase Ataxia-Telangiectasia Mutated (ATM). Recently, ATM has been also involved in the regulation of several metabolic processes, but whether and how it affects cardiac metabolism is still poorly understood.

Purpose

We hypothesized that ATM might play crucial roles in the maintenance of cardiomyocyte metabolic homeostasis and in the development of cardiac dysfunction in response to pressure overload.

Methods

Atm+/+ and Atm homozygous mutated mice (Atm−/−) underwent transverse aortic constriction (TAC) or sham operation (sham). After one week (1w), sham and TAC mice were anesthetized, cardiac function and morphometry were analyzed, and gene expression reprogramming, cardiac histology, mitochondrial morphology were performed. Metabolic profiling was carried out through untargeted metabolomics (LC-MS/MS and GC/MS), mRNA and/or protein levels analysis to investigate glycolyis, pyruvate oxidation, Krebs cycle, aminoacid synthesis, gluconeogenesis and lipid oxidation.

Results

Atm genetic inactivation induced cardiomyocytes hypertrophy and fetal gene reprogramming in sham mice, with normal cardiac function and in the absence of fibrosis or mitochondrial dysfunction (Figure 1A). After TAC 1w, cardiac function was significantly decreased in Atm−/− mice, compared to Atm+/+ (Figure 1B). In both sham and TAC 1w Atm−/− mice, significant metabolic abnormalities were identified, including switching of glycolysis, reduction of pyruvate oxidation (Figure 1B), activation of aminoacid synthesis and accumulation of long and short-chain fatty acid conjugated with carnitine. Pyruvate accumulation was associated to a significant reduction of pyruvate carrier (MPC1-MPC2) and pyruvate dehydrogenase (PDH) levels in sham and TAC 1w Atm−/− mice.

Conclusions

ATM regulates gene expression, cardiomyocyte hypertrophy and cardiac responses to pressure overload, modulating cardiac metabolism and the profile of intracellular substrate utilization in the heart. Thus, ATM might represent a novel important player in the development of cardiac dysfunction and a novel therapeutic target.

Figure 1

Funding Acknowledgement

Type of funding source: Other. Main funding source(s): CP was supported by Ministero dell'Istruzione, Università e Ricerca Scientifica grant (2015583WMX) and Programma STAR grant by Federico II University and Compagnia di San Paolo. RP was supported by a research grant provided by the Cardiopath PhD program.

Aging-associated cardiac dysfunction and leaky gut in heterozygous Akap1 knockout mice

Background

Mitochondrial A-kinase anchoring proteins (mitoAKAPs) encoded by the Akap1 gene are crucially involved in multiple cellular processes, including cardiomyocyte survival and function. There is a correlation between ROS production, intestinal permeability and the composition of the intestinal microbiota, especially during aging. Whether Akap1 deletion affects microbiota composition, intestinal function during senescence is currently unknown.

Purpose

The purpose of the study was to shed light into the complex interplay between gut permeability and microbiota composition, cardiac function and aging in adult (6-month-old, 6m) and old (24-month-old, 24m) Akap 1 wild type (Akap1+/+) or Akap1 heterozygous knockout mice (Akap1+/−).

Methods

Cardiac function was non-invasively analyzed by echocardiography in adult and old, Akap1+/+ and Akap1+/− mice. Colon, serum and feces samples were collected after sacrifice in 6m and 24m mice of either genotype. Intestinal barrier permeability was evaluated in colon samples by Occludin (Ocln) and Tight junction protein ZO-1 (Tjp1) mRNA expression analysis. Systemic inflammation was measured by Tumor Necrosis Factor-alpha (TNF-alpha), Lipopolysaccharide (LPS), Interleukin-10 (IL-10) and Interleukin-1 (IL-1) circulating levels. Microbial DNA was extracted from feces samples and gut microbiota composition was evaluated by Illumina Mi-Seq analysis. Bioinformatic analyses were carried out to identify intestinal populations.

Results

Akap1 partial deletion accelerated the progression of cardiac dysfunction in 24m mice as demonstrated by a significant reduction of fractional shortening in Akap1+/− 24m mice compared to Akap1+/+ 24m (Figure 1A). Colon permeability was impaired in Akap1+/− 24m as shown by reduced Ocln expression (Figure 1B), while circulating TNF-alpha was increased in Akap1+/− 24m (Figure 1C). Next, we analyzed the differences in abundance of all 2042 Operational Taxonomic Units (OTUs) between age-matched Akap1+/+ and Akap1+/−. We identified 10 OTUs differently represented in Akap1+/+ and Akap1+/− 6m mice, while a bigger set of bacterial OTUs (19) were different between Akap1+/+ and Akap1+/− 24m mice. LDA scores of differentially microbiome abundant taxa in Akap1+/+ and Akap1+/− 24m (Figure 1D) showed different assortment in Clostridiales family (Ruminococcus torques specie), Porphyromonadaceae family (Barseniella intestinihominis specie) and Lachnospiraceae genus (Blautia producta specie), bacterial species that have been previously identified in patients with heart failure and involved in anti-inflammatory mechanisms.

Conclusions

mitoAKAPs play a crucial role in the maintenance of cardiac function and intestinal barrier during aging, since Akap1 partial deletion promotes gut permeability, bacteria translocation and systemic inflammation associated with systolic cardiac dysfunction.

Figure 1

Funding Acknowledgement

Type of funding source: Other. Main funding source(s): CP was supported by Ministero dell'Istruzione, Università e Ricerca Scientifica grant (2015583WMX) and Programma STAR grant by Federico II University and Compagnia di San Paolo. RP was supported by a research grant provided by the Cardiopath PhD program. LC was supported by 2018-2019 Postdoctoral Fellowship Grants provided by Fondazione Umberto Veronesi.

Antibody-reactive class I epitopes defined by pairs of mismatched eplets and self-eplets

The identification of human leukocyte antigen (HLA) antibodies in the sera of candidates awaiting organ transplantation has evolved over time. This has been possible because of the introduction of more sensitive techniques and to the increasing focus on the structural aspects of the HLA epitopes. The use of the HLAMatchmaker algorithm in the analysis of positive sera and the verification of HLA ABC epitopes in the HLA Epitope Registry website provide new stimuli on the interpretation of antibody reactivity. The epitopes defined by eplet pairs often involve a nonself-eplet and a self-eplet (nonself-self paradigm), suggesting that the antibody response to an HLA mismatch must have an auto-reactive component. Here, we report an application of the nonself-self paradigm that provides a basis for better knowledge and interpretation of HLA-antibody reactivity in Luminex assays with single alleles.

Expression of IL-23, VEGF and TLR2/TLR4 on mononuclear cells after exposure to Pseudomonas aeruginosa

Pseudomonas aeruginosa is a Gram-negative, aerobic bacillus causing infections of the respiratory and other organ systems in susceptible hosts. Although it does not cause pulmonary infections in immunocompetent individuals, P. aeruginosa causes chronic lung infection in individuals with cystic fibrosis and nosocomial pneumonia resulting in significant morbidity and mortality. Exogenous administration of an important P. aeruginosa virulence factor, lipase, present in P. aeruginosa culture supernatant, induces potent mononuclear cell activation leading to the production of numerous proinflammatory cytokines. In particular, P. aeruginosa culture supernatant stimulated increased proliferation of THP-1 cells and monocytes (MN). The addition of culture supernatant to THP-1 cells and MN also induced Interleukin (IL)-23 and vascular endothelial growth factor (VEGF) release in a time-dependent manner. To investigate whether any compounds present in the supernatant lipase contributed to releasing IL-23 and VEGF, the culture supernatant from P. aeruginosa containing lipase was treated with hexadecylsulfonylfluoride (AMSF). The AMSF-treated culture supernatant (CS) did not show any induction on the IL-23 and VEGF release compared to the cells treated with CS without AMSF. We also showed that Toll-like receptors (TLR)2/TLR4 are expressed in THP-1 cells and MN treated with P. aeruginosa CS in a time-dependent fashion. Flow cytometry analysis revealed a higher TLR4 and a lower TLR2 expression at 48 and 72 h of treatment. The treatment of cells with TLR4 neutralizing antibody, and to a lesser extent with TLR2 neutralizing antibody, resulted in a decrease in P. aeruginosa CS-induced IL-23 and VEGF production.

Use of glucocorticoids in pregnancy

For many years glucocorticoids have been used world-wide in pregnant women for treatment of a variety of medical disorders, from bronchial asthma to systemic lupus erythematosous, to renal transplant. More recently their administration has been successfully addressed to the prevention of congenital fetal diseases. In some of these, such as for instance the 21-hydroxylase deficiency leading to congenital adrenal hyperplasia, the pathogenic mechanism is well known, while in others, such as the cystic adenomatoid malformation of the lung, it is not yet understood. Besides these types of diseases, there are acquired inflammatory conditions impairing the physiologic evolution of pregnancy that benefit from glucocorticoid administration. This is the case in recurrent miscarriage due to increased concentration of decidual Natural Killer cells, as well as in the Romero's syndrome, leading to premature parturition and related life threatening fetal complications. However, in spite of its prominent efficacy, the therapy is generally viewed with some suspicion because of possible fetal and maternal adverse effects. With the aim to contribute to a better knowledge of the basic mechanisms of glucocorticoid protection, we reviewed the regulation of their trans-placental passage, their biological effects on gestational environment, their possible 'programming' and teratogenic action, and their accepted use for prevention and cure of pregnancy complications. We believe that a more qualified and liberal use of these compounds will lead in many cases to a significant improvement of fetal and maternal prognosis.

Relationship between Chlamydia pneumoniae infection, inflammatory markers, and coronary heart diseases

Chlamydia pneumoniae is an intracellular pathogen and an important cause of respiratory tract infections in humans and more recently it has been associated with chronic diseases such as atherosclerosis. Numerous studies have been performed to show the "infectious" hypothesis of atherosclerosis by direct detection of the organisms within atheromatous plaques by seroepidemiological estimation and by animal, immunological and antibiotic interventional studies. In this work we investigated the relation between chronic chlamydial infection, inflammatory markers, Interleukin 7 (IL-7) production and coronary heart disease. We studied 60 patients with coronary heart diseases (CHD), 45 of whom were men and 15 women, with a mean age of 65+/-5 years, and a control group of 20 healthy subjects, 15 men and 5 women, with a mean age of 60+/-7 years. Detailed histories including symptoms, risk factors and demographic data were obtained from patients and healthy subjects by administering a standardized questionnaire. Our results demonstrate that the enzyme-linked immunoassay (ELISA) test appears to have a greater sensitivity than the microimmunofluorescence (MIF) technique. 80% of patients had positive IgG to C. pneumoniae and 58% positive IgA to C. pneumoniae with ELISA, while the MIF test showed 68% and 55% positive IgG and IgA to C. pneumoniae, respectively. The control subjects showed 55% positive IgG and 10% IgA to C. pneumoniae by ELISA and 35% positive IgG and 5% IgA to C. pneumoniae by MIF. The combination of positive IgG and IgA to C. pneumoniae was present more frequently than in the control group. Serum levels of IL-7 measured by ELISA were also significantly higher in patients compared to healthy subjects. In conclusion, our study shows that C. pneumoniae IgG and IgA seropositivity, inflammatory markers such as IL-7, fibrinogen, C-reactive protein were significantly correlated with CHD.