Aims Immune checkpoint inhibitors (ICIs) have revolutionized cancer treatment. However, their use often leads to cardiovascular adverse effects, including cardiac dysfunction. Here, we hypothesized that a prior cardiac ischaemic injury could exacerbate cardiac dysfunction due to anti-programmed death protein 1 (PD-1) treatment. Furthermore, we investigated whether abatacept, a T-cell costimulation blocker, could ameliorate the ICI-induced cardiotoxicity in a pre-clinical model.Methods and results In a pre-clinical study, mice were treated with isoprenaline or control to induce reversible cardiac ischaemia. After 16 weeks of follow-up, recovery of cardiac function was confirmed via echocardiography, and mice from both groups were randomly treated with isotype control, anti-PD-1, or anti-PD-1 combined with abatacept, for 2 further weeks. Mice with prior ischaemic injury and anti-PD-1 treatment showed cardiac dysfunction with increased infiltration of T cells and macrophages and elevated expression of pro-inflammatory cytokines. Conversely, cardiac dysfunction and inflammation were less pronounced after anti-PD-1 treatment in mice without prior ischaemic injury. Mice with concomitant abatacept treatment exhibited normal cardiac function and alleviated pro-inflammatory response. In a parallel single-centre retrospective clinical cohort study, 1671 cancer patients receiving PD-1 inhibitors were analysed. Cases were defined as patients who developed incident heart failure (HF) after ICI initiation with a primary aim to test whether pre-existing ischaemic heart disease was associated with an increased risk for HF development post-ICI therapy. Sensitivity analyses included propensity score matching and comparison with non-ICI-treated cancer patients. Among ICI-treated patients, 109 (6.5%) developed HF over a median follow-up of 332 days. Multivariable logistic regression of the matched population showed increased odds of incident HF in patients with prior ischaemic cardiac events (odds ratio 2.11, 95% confidence interval 1.05-4.2, P = 0.033).Conclusion In mice, induction of cardiac inflammation and dysfunction by anti-PD-1 therapy was potentiated by prior transient ischaemic cardiac injury, which was ameliorated by abatacept cotreatment. Cancer patients with pre-existing ischaemic heart disease may be at greater risk for developing ICI-induced new-onset HF. Based on our findings, cardiac surveillance should be considered in patients starting ICI therapy with a prior history of ischaemic heart disease.

Type 2 diabetes mellitus (T2DM) represents a significant risk factor for cardiovascular disease, particularly heart failure with preserved ejection fraction (HFpEF). HFpEF predominantly affects elderly individuals and women, and is characterized by dysfunctions associated with metabolic, inflammatory, and oxidative stress pathways. Despite HFpEF being the most prevalent heart failure phenotype in patients with T2DM, its underlying pathophysiological mechanisms remain inadequately elucidated. This study aims to investigate the effects of diabetes mellitus on myocardial inflammation, oxidative stress, and protein quality control (PQC) mechanisms in HFpEF, with particular emphasis on insulin signaling, autophagy, and chaperone-mediated stress responses. We conducted an analysis of left ventricular myocardial tissue from HFpEF patients, both with and without diabetes, employing a range of molecular, biochemical, and functional assays. The passive stiffness of cardiomyocytes (Fpassive) was assessed in demembranated cardiomyocytes before and after implementing treatments aimed at reducing inflammation (IL-6 inhibition), oxidative stress (Mito-TEMPO), and enhancing PQC (HSP27, HSP70). Inflammatory markers (NF-κB, IL-6, TNF-α, ICAM-1, VCAM-1, NLRP3), oxidative stress markers (ROS, GSH/GSSG ratio, lipid peroxidation), and components of signaling pathways (PI3K/AKT/mTOR, AMPK, MAPK, and PKG) were evaluated using western blotting, immunofluorescence, and ELISA techniques. Hearts from diabetic HFpEF patients exhibited significantly heightened inflammation, characterized by the upregulation of NF-κB, IL-6, and the NLRP3 inflammasome. This increase in inflammation was accompanied by elevated oxidative stress, diminished nitric oxide (NO) bioavailability, and impaired activation of the NO-sGC-cGMP-PKG signaling pathway. Notably, dysregulation of insulin signaling was observed, as indicated by decreased AKT phosphorylation and impaired autophagy regulation mediated by AMPK and mTOR. Additionally, PQC dysfunction was evidenced by reduced expression levels of HSP27 and HSP70, which correlated with increased cardiomyocyte passive stiffness. Targeted therapeutic interventions effectively reduced Fpassive, with IL-6 inhibition, Mito-TEMPO, and HSP administration leading to improvements in cardiomyocyte mechanical properties. The findings of this study elucidate a mechanistic relationship among diabetes, inflammation, oxidative stress, and PQC impairment in the context of HFpEF. Therapeutic strategies that target these dysregulated pathways, including IL-6 inhibition, mitochondrial antioxidants, and chaperone-mediated protection, may enhance myocardial function in HFpEF patients with T2DM. Addressing these molecular dysfunctions could facilitate the development of novel interventions specifically tailored to the diabetic HFpEF population.

Incretin analogues, used for the treatment of type 2 diabetes mellitus and obesity, such as GLP1-receptor agonist liraglutide (Lira) have been shown to reduce major adverse cardiac events in recent clinical trials of heart failure. Tirzepatide (TZP), a dual GIP/GLP1-receptor agonist has shown promising results in the SUMMIT trial as improved cardiovascular outcomes in patients with heart failure with preserved ejection fraction (HFpEF). However, data regarding their use in heart failure with reduced ejection fraction (HFrEF) is lacking. We performed a head-to-head comparative study in a mouse model of non-ischaemic cardiac injury induced by continuous angiotensin II (AngII) infusion, as AngII is a key driver of both heart failure forms. Osmotic minipumps were inserted for subcutaneous (s.c.) administration of AngII (1.5 mg/kg/day) in 5-month-old male Balb/c mice or sham surgery was performed. Animals were treated with vehicle (Veh), Lira (300 µg/day i.p.) or TZP (48 µg/day s.c.) for 14 days in the following groups: Sham/Veh (n = 7), AngII/Veh (n = 15), Sham/Lira (n = 7), AngII/Lira (n = 15), Sham/TZP (n = 8), AngII/TZP (n = 15). Cardiac structural, functional and molecular characteristics were assessed by echocardiography, ECG, immunohistochemistry, flow cytometry and qRT-PCR. Mortality was significantly higher in AngII/Veh animals compared to controls, while AngII/TZP mice showed significantly reduced mortality after 14 days of treatment. Both Lira and TZP caused significant weight reduction compared to controls. AngII given alone also reduced body mass, and this reduction was further enhanced by TZP. Treatment with both compounds preserved cardiac systolic and diastolic function compared with AngII/Veh animals, as shown by normal ejection fraction and E/e’, respectively. Both Lira and TZP decreased the AngII-induced elevation of cardiac fibrosis and hypertrophy markers, including Ctgf, Col1a1, Col3a1, and Nppa, while TZP also reduced the elevated Nppb level. TZP also reduced systemic inflammation, as shown by the reduction in serum CRP levels. Lira and TZP preserved cardiac function and decreased markers of hypertrophy and fibrosis in mice with AngII-induced heart failure, whereas TZP also significantly decreased mortality. In addition to HFpEF, the use of incretin analogues may also be of clinical relevance in the treatment of HFrEF. However, as patients with heart failure, AngII level is elevated and can cause weight loss/cachexia, the usage of incretin analogues to treat non-obese heart failure patients should be considered.

Despite accumulating data on underlying mechanisms, the influence of sex and prevalent cardio-metabolic co-morbidities on the manifestation and severity of immune checkpoint inhibitor (ICI)-induced cardiotoxicity has not been well defined. To elucidate whether sex and prevalent cardio-metabolic co-morbidities affect ICI-induced cardiotoxicity, we randomized 17-month-old male and female mice to receive control diet (CON) or high-fat diet (HFD) + L-NAME—a well-established mouse model of cardio-metabolic co-morbidities—for 17 weeks (n = 5–7), and evaluated markers of T-cell function in the spleen. As expected, HFD + L-NAME significantly increased body- and heart weight, and serum cholesterol levels, and caused no systolic dysfunction, however, led to diastolic dysfunction, cardiomyocyte hypertrophy, and increased fibrosis only in males compared to corresponding CON. Western blot analyses of splenic immune checkpoint protein levels showed differential expression depending on sex and prevalent cardio-metabolic co-morbidities, suggesting T-cell exhaustion in both sexes on HFD + L-NAME, but more pronounced in males. In a sub-study with a similar setup, we tested cardiotoxic manifestations of ICI by treating mice with anti-PD-1 monoclonal antibody (ICI) for the last 2 weeks of diet administration (n = 5–7). After 2 weeks of ICI treatment, cardiac systolic functions significantly decreased in CON, but not in HFD + L-NAME groups of both sexes compared to baseline (before ICI administration). In conclusion, in this exploratory study using aged mice, we describe for the first time that ICI-related systolic dysfunction is diminished in both sexes when obesity and hypercholesterolemia are present, possibly due to obesity-related T-cell exhaustion.

AbstractAimsHeart failure with reduced ejection fraction (HFrEF) is a leading cause of death worldwide; thus, therapeutic improvements are needed. In vivo preclinical models are essential to identify molecular drug targets for future therapies. Transverse aortic constriction (TAC) is a well‐established model of HFrEF; however, highly experienced personnel are needed for the surgery, and several weeks of follow‐up are necessary to develop HFrEF. To this end, we aimed (i) to develop an easy‐to‐perform mouse model of HFrEF by treating Balb/c mice with angiotensin‐II (Ang‐II) for 2 weeks by minipump and (ii) to compare its cardiac phenotype and transcriptome to the well‐established TAC model of HFrEF in C57BL/6J mice.MethodsMortality and gross pathological data, cardiac structural and functional characteristics assessed by echocardiography and immunohistochemistry and differential gene expression obtained by RNA‐sequencing and gene‐ontology analyses were used to characterize and compare the two models. To achieve statistical comparability between the two models, changes in treatment groups related to the corresponding control were compared (ΔTAC vs. ΔAng‐II).ResultsCompared with the well‐established TAC model, chronic Ang‐II treatment of Balb/c mice shares similarities in cardiac systolic functional decline (left ventricular ejection fraction: −57.25 ± 7.17% vs. −43.68 ± 5.31% in ΔTAC vs. ΔAng‐II; P = 0.1794) but shows a lesser degree of left ventricular dilation (left ventricular end‐systolic volume: 190.81 ± 44.13 vs. 57.37 ± 10.18 mL in ΔTAC vs. ΔAng‐II; P = 0.0252) and hypertrophy (cell surface area: 58.44 ± 6.1 vs. 10.24 ± 2.87 μm2 in ΔTAC vs. ΔAng‐II; P < 0.001); nevertheless, transcriptomic changes in the two HFrEF models show strong correlation (Spearman's r = 0.727; P < 0.001). In return, Ang‐II treatment in Balb/c mice needs significantly less procedural time [38 min, interquartile range (IQR): 31–46 min in TAC vs. 6 min, IQR: 6–7 min in Ang‐II; P < 0.001] and surgical expertise, is less of an object for peri‐procedural mortality (15.8% in TAC vs. 0% in Ang‐II; P = 0.105) and needs significantly shorter follow‐up for developing HFrEF.ConclusionsHere, we demonstrate for the first time that chronic Ang‐II treatment of Balb/c mice is also a relevant, reliable but significantly easier‐to‐perform preclinical model to identify novel pathomechanisms and targets in future HFrEF research.

Both heart failure with preserved ejection fraction (HFpEF) and non-alcoholic fatty liver disease (NAFLD) develop due to metabolic dysregulation, has similar risk factors (e.g., insulin resistance, systemic inflammation) and are unresolved clinical challenges. Therefore, the potential link between the two disease is important to study. We aimed to evaluate whether NASH is an independent factor of cardiac dysfunction and to investigate the age dependent effects of NASH on cardiac function. C57Bl/6 J middle aged (10 months old) and aged mice (24 months old) were fed either control or choline deficient (CDAA) diet for 8 weeks. Before termination, echocardiography was performed. Upon termination, organ samples were isolated for histological and molecular analysis. CDAA diet led to the development of NASH in both age groups, without inducing weight gain, allowing to study the direct effect of NASH on cardiac function. Mice with NASH developed hepatomegaly, fibrosis, and inflammation. Aged animals had increased heart weight. Conventional echocardiography revealed normal systolic function in all cohorts, while increased left ventricular volumes in aged mice. Two-dimensional speckle tracking echocardiography showed subtle systolic and diastolic deterioration in aged mice with NASH. Histologic analyses of cardiac samples showed increased cross-sectional area, pronounced fibrosis and Col1a1 gene expression, and elevated intracardiac CD68+ macrophage count with increased Il1b expression. Conventional echocardiography failed to reveal subtle change in myocardial function; however, 2D speckle tracking echocardiography was able to identify diastolic deterioration. NASH had greater impact on aged animals resulting in cardiac hypertrophy, fibrosis, and inflammation.

Introduction: Immune checkpoint inhibitors (ICI), such as anti-PD-1 monoclonal antibodies are increasingly used in anti-cancer therapy. However, several cardiovascular adverse effects can occur with the use of ICIs, including new-onset heart failure. Hypothesis: We hypothesized that prior myocardial ischemic injury could exacerbate cardiac dysfunction and inflammation caused by anti-PD-1 treatment. Moreover, we investigated whether abatacept, a T-cell co-stimulation blocker, can prevent ICI-induced cardiac effects. Methods: To induce reversible cardiac ischemia, C57Bl/6J mice were treated with isoprenaline (ISOP group) or with PBS (CON group), followed by 16 weeks of recovery period. Following this, mice from both groups were divided into three further treatment groups: isotype control, anti-PD-1, or anti-PD-1 combined with abatacept, and were treated for two weeks, with three weekly intraperitoneal injections. Echocardiography was performed to evaluate cardiac function while myocardial inflammation was assessed by qRT-PCR and immunohistochemistry. Flow cytometry and Western blot were used to investigate changes occurring in the thymus. Results: Mice with normal heart function but with prior ischemic injury and anti-PD-1 treatment (ISOP + anti-PD-1) showed significantly decreased fractional shortening and cardiac index on echocardiography, while in animals with abatacept co-treatment (ISOP+anti-PD-1+abatacept) cardiac function was not altered. Increased immune cell infiltration was seen in the myocardium of the ISOP+anti-PD-1 treated group compared to CON animals, including T-cells and macrophages, with increased expression of pro-inflammatory cytokines, while co-treatment with abatacept ameliorated the inflammatory response. In the thymus, increased expression of PD-1 was found after abatacept co-treatment. Conclusion: Prior myocardial ischemic injury was associated with cardiac dysfunction and inflammation after anti-PD-1 treatment, which was ameliorated by abatacept co-treatment. Patients with prior cardiac ischemic events may be at greater risk for developing ICI-induced cardiotoxicity, including new-onset HF.

AbstractBackgroundCardiac remodelling, a crucial aspect of heart failure, is commonly investigated in preclinical models by quantifying cardiomyocyte cross‐sectional area (CSA) and microvascular density (MVD) via histological methods, such as immunohistochemistry. To achieve this, optimized protocols are needed, and the species specificity is dependent on the antibody used. Lectin histochemistry offers several advantages compared to antibody‐based immunohistochemistry, including as cost‐effectiveness and cross‐species applicability. Direct comparisons between the two methods are lacking from the literature.Methods and resultsIn this study, we compared antibody‐ and lectin‐based methods for the histological assessment of cardiomyocyte CSA (with the use of anti‐laminin and wheat germ agglutinin [WGA]) and microvascular density (utilizing anti‐CD31 and isolectin B4 [ILB4]) using different embedding and antigen/carbohydrate retrieval techniques. Here, we describe a detailed, easy‐to‐use combined lectin histochemistry protocol (WGA and ILB4, ‘CardiLect’ protocol) for the histological assessment of cardiac remodelling. The lectin‐based approach has been evaluated on a cross‐species basis, and its efficacy has been demonstrated in zebrafish, rodents, large animals and human samples. We provide an ImageJ script (‘CardiLect Analyser’) for automated image analysis, validated in a preclinical heart failure model by correlating histological parameters with echocardiographic findings. CSA showed a significant positive correlation with left ventricular (LV) mass (P = 0.0098, rS = 0.7545) and significant negative correlation with markers of systolic function, such as ejection fraction (EF) (P = 0.0402, rS = −0.6364). Microvascular density showed significant negative correlation with LV mass (P = 0.0055, rS = −0.7622) and significant positive correlation with EF (P = 0.0106, rS = 0.7203).ConclusionsThe described combined lectin histochemistry protocol with the provided ImageJ script is an easy‐to‐use, cost‐effective, cross‐species approach for the histological assessment of cardiac remodelling.

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Momentum grant of the Hungarian Academy of Sciences Introduction Immune checkpoint inhibitors (ICI), such as monoclonal antibodies targeting programmed death ligand-1 (PD-1), revolutionized cancer treatment. However, they can lead to several cardiovascular adverse effects, ranging from mild cardiac dysfunction to fulminant, lethal myocarditis. Nevertheless, the mechanisms and risk factors behind the diverse forms of ICI-induced cardiotoxicity are not entirely understood currently. Purpose In this study, we hypothesized that a prior cardiac ischemic injury, leading to acute immune cell infiltration and activation, but without subsequent heart failure, can exacerbate the cardiotoxicity and cardiac inflammation caused by anti-PD-1 monoclonal antibodies. Furthermore, we aimed to investigate in our mouse model whether abatacept, an inhibitor of T-cell co-stimulation, can ameliorate ICI-induced cardiac effects. Methods First, we treated 8 weeks-old C57BL/6J mice with isoprenaline (ISOP group, 160 mg/kg, n = 43) or with its solvent (CON group, n = 38), to induce reversible cardiac ischemia. Validation of the ischemic injury was performed in 6 randomly selected animals from each group two days after the treatment with histology and echocardiography. After this, the animals underwent 16 weeks of recovery period, followed by echocardiography to confirm cardiac functional recovery. Here, mice from both groups were randomized to three further treatment groups: isotype control, anti-PD-1 alone, or anti-PD-1 combined with abatacept and were treated for two weeks, with three weekly intraperitoneal injections (immune checkpoint inhibition phase). Echocardiography, qRT-PCR and histology was performed to evaluate cardiac function and inflammation. Results Two days after the initial ISOP treatment, mice displayed significant reduction in ejection fraction and infiltration of inflammatory cells were seen on histology. During the recovery period, 8 mice from the ISOP group and one mouse from the CON died. After the immune checkpoint inhibition phase, mice with prior ischemic injury and anti-PD-1 treatment (ISOP + anti-PD-1 alone) showed significant cardiac dysfunction on echocardiography, while animals with abatacept treatment (ISOP+anti-PD-1+abatacept) showed normal cardiac function. With qRT-PCR and histology, increased infiltration of T-cells and macrophages was seen in the myocardium of the ISOP+anti-PD-1 treated group compared to CON animals, with increased expression of pro-inflammatory cytokines, including Il17a, Il23 and Ifng. However, no cardiac infiltration was seen in mice without prior ischemic injury and the pro-inflammatory cytokine response was less pronounced as well. Conclusions Prior cardiac ischemic injury without overt cardiac dysfunction exacerbates cardiac inflammation and cardiotoxicity induced by anti-PD-1 immune checkpoint inhibition therapy. Patients with pre-existing ischemic heart disease may be at greater risk for developing ICI-induced severe cardiac adverse events.Hypothesis

Background and PurposeImmune checkpoint inhibitors (ICI), such as anti-PD-1 monoclonal antibodies, have revolutionized cancer therapy by enhancing the cytotoxic effects of T-cells against tumours. However, enhanced T-cell activity also may cause myocarditis and cardiotoxicity. Our understanding of the mechanisms of ICI-induced cardiotoxicity is limited. Here, we aimed to investigate the effect of PD-1 inhibition on cardiac function and explore the molecular mechanisms of ICI-induced cardiotoxicity. Experimental ApproachC57BL6/J and BALB/c mice were treated with isotype control or anti-PD-1 antibody.Echocardiography was used to assess cardiac function. Cardiac transcriptomic changes were investigated by bulk RNA sequencing. Inflammatory changes were assessed by qRT-PCR and immunohistochemistry in heart, thymus, and spleen of the animals. In follow-up experiments, anti-CD4 and anti-IL-17A antibodies were used along with PD-1 blockade in C57BL/6J mice. Key ResultsAnti-PD-1 treatment led to cardiac dysfunction and left ventricular dilation in C57BL/6J mice, with increased nitrosative stress. Only mild inflammation was observed in the heart. However, PD-1 inhibition resulted in enhanced thymic inflammatory signalling, where Il17a increased most prominently. In BALB/c mice, cardiac dysfunction was not evident, and thymic inflammatory activation was more balanced. Inhibition of IL-17A prevented anti-PD-1-induced cardiac dysfunction in C57BL6/J mice. Comparing myocardial transcriptomic changes in C57BL/6J and BALB/c mice, differentially regulated genes (Dmd, Ass1, Chrm2, Nfkbia, Stat3, Gsk3b, Cxcl9, Fxyd2, and Ldb3) were revealed, related to cardiac structure, signalling, and inflammation. ConclusionsPD-1 blockade induces cardiac dysfunction in mice with increased IL-17 signalling in the thymus. Pharmacological inhibition of IL-17A treatment prevents ICI-induced cardiac dysfunction.

The identification of novel drug targets is needed to improve the outcomes of heart failure (HF). G-protein-coupled receptors (GPCRs) represent the largest family of targets for already approved drugs, thus providing an opportunity for drug repurposing. Here, we aimed (i) to investigate the differential expressions of 288 cardiac GPCRs via droplet digital PCR (ddPCR) and bulk RNA sequencing (RNAseq) in a rat model of left ventricular pressure-overload; (ii) to compare RNAseq findings with those of ddPCR; and (iii) to screen and test for novel, translatable GPCR drug targets in HF. Male Wistar rats subjected to transverse aortic constriction (TAC, n = 5) showed significant systolic dysfunction vs. sham operated animals (SHAM, n = 5) via echocardiography. In TAC vs. SHAM hearts, RNAseq identified 69, and ddPCR identified 27 significantly differentially expressed GPCR mRNAs, 8 of which were identified using both methods, thus showing a correlation between the two methods. Of these, Prostaglandin-F2α-receptor (Ptgfr) was further investigated and localized on cardiomyocytes and fibroblasts in murine hearts via RNA-Scope. Antagonizing Ptgfr via AL-8810 reverted angiotensin-II-induced cardiomyocyte hypertrophy in vitro. In conclusion, using ddPCR as a novel screening method, we were able to identify GPCR targets in HF. We also show that the antagonism of Ptgfr could be a novel target in HF by alleviating cardiomyocyte hypertrophy.

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – EU funding. Main funding source(s): European Union's Horizon 2020 research and innovation programme National Research, Development and Innovation Fund of Hungary Background Cardiac cell lines and primary cell cultures are widely used to model various cardiovascular diseases in vitro. Despite the increasing number of publications using these models, limitations of these cell lines are still undetermined. Purpose The aim of our study was to compare the most commonly used cardiac cell lines to primary cultures and to mature cardiac tissues by transcriptomic analysis and morphological characterization. Methods H9C2 (rat), AC16 (human) and HL-1 (mouse) cardiac cell lines were differentiated towards a phenotype more resembling cardiomyocytes, by methods most widely used in the literature, and cells were harvested at stages of proliferation and differentiation. Whole left ventricular tissue, neonatal primary cardiac myocytes isolated from mice and rats, or human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CM) were applied as references. Transcriptome analysis and immunocytochemical detection of cardiac structural proteins were performed on all cell models. Results RNA expression of cardiac markers (e.g. Tnnt2, Ryr2, Tnni3) was markedly lower in cell lines compared to primary cells or hiPSC-CM and adult tissue controls. Differentiation procedures induced a significant increase in cardiac- and decrease in embryonic markers in AC16 and H9C2 lines; however, the overall expression pattern of investigated genes in all cell lines showed significant differences in comparison to corresponding myocardium or primary cultures. Immunocytochemistry confirmed low expressions of structural protein alpha-actinin and troponin I in cell lines. Conclusion Expression patterns of cardiomyocyte markers and mRNA profile indicates low-to-moderate similarity of cell lines to primary cells/cardiac tissues regardless the differentiation protocol used. These limitations should be taken into account while choosing cells as in vitro platforms to model cardiomyocytes and cardiovascular diseases.

Previously, the presence of a blood-myenteric plexus barrier and its disruption was reported in experimentally induced colitis via a macrophage-dependent process. The aim of this study is to reveal how myenteric barrier disruption and subsequent neuronal injury affects gut motility in vivo in a murine colitis model. We induced colitis with dextran sulfate sodium (DSS), with the co-administration of liposome-encapsulated clodronate (l-clodronate) to simultaneously deplete blood monocytes contributing to macrophage infiltration in the inflamed muscularis of experimental mice. DSS-treated animals receiving concurrent l-clodronate injection showed significantly decreased blood monocyte numbers and colon muscularis macrophage (MM) density compared to DSS-treated control (DSS-vehicle). DSS-clodronate-treated mice exhibited significantly slower whole gut transit time than DSS-vehicle-treated animals and comparable to that of controls. Experiments with oral gavage-fed Evans-blue dye showed similar whole gut transit times in DSS-clodronate-treated mice as in control animals. Furthermore, qPCR-analysis and immunofluorescence on colon muscularis samples revealed that factors associated with neuroinflammation and neurodegeneration, including Bax1, Hdac4, IL-18, Casp8 and Hif1a are overexpressed after DSS-treatment, but not in the case of concurrent l-clodronate administration. Our findings highlight that MM-infiltration in the muscularis layer is responsible for colitis-associated dysmotility and enteric neuronal dysfunction along with the release of mediators associated with neurodegeneration in a murine experimental model.

Interleukin-1β (IL-1β) is a key mediator of non-alcoholic steatohepatitis (NASH), a chronic liver disease, and of systemic inflammation-driven aging. IL-1β contributes to cardio-metabolic decline, and may promote hepatic oncogenic transformation. Therefore, IL-1β is a potential therapeutic target in these pathologies. We aimed to investigate the hepatic and cardiac effects of an IL-1β targeting monoclonal antibody in an aged mouse model of NASH. 24 months old male C57Bl/6J mice were fed with control or choline deficient (CDAA) diet and were treated with isotype control or anti-IL-1β Mab for 8 weeks. Cardiac functions were assessed by conventional—and 2D speckle tracking echocardiography. Liver samples were analyzed by immunohistochemistry and qRT-PCR. Echocardiography revealed improved cardiac diastolic function in anti-IL-1β treated mice with NASH. Marked hepatic fibrosis developed in CDAA-fed group, but IL-1β inhibition affected fibrosis only at transcriptomic level. Hepatic inflammation was not affected by the IL-1β inhibitor. PCNA staining revealed intensive hepatocyte proliferation in CDAA-fed animals, which was not influenced by neutralization of IL-1β. IL-1β inhibition increased hepatic expression of Pd-1 and Ctla4, while Pd-l1 expression increased in NASH. In conclusion, IL-1β inhibition improved cardiac diastolic function, but did not ameliorate features of NASH; moreover, even promoted hepatic immune checkpoint expression, with concomitant NASH-related hepatocellular proliferation.

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – EU funding. Main funding source(s): European Union’s Horizon 2020 Research and Innovation Programme under grant agreement no. 739593 “Semmelweis 250+ Kiválósági PhD Ösztöndíj” (EFOP-3.6.3-VEKOP-16-2017-00009) Gedeon Richter Talentum Foundation’s scholarship Background Immune checkpoint inhibitors have revolutionized the treatment of several form of malignancies (including metastatic melanoma) by enhancing the cytotoxic effects of T cells against cancer cells. Cancer cells evade immune surveillence by increasing the expression of T cell inhibitory molecules, also known as immune checkpoints, such as programmed cell death-1 (PD-1). Pharmacological inhibition of these molecules by immune checkpoint inhibitors (ICI) will enhance the antitumor activity of T cells. However, enhanced T cell activity may cause immune related adverse effects, including cardiotoxicity. Aims We aimed to investigate the effect of PD-1 inhibition on cardiac function and the underlying mechanisms in mice. Methods 8-10 weeks old C57BL6/J mice were treated with isotype control or anti-PD-1 antibody for 2 or 4 weeks. Cardiac function and morphology was assessed by echocardiography and histology, while the transcriptomic changes were analyzed via RNA sequencing. Nitrosative stress in the heart was assessed by immunohistochemistry and qRT-PCR. Inflammatory gene expression alterations were determined by qRT-PCR in the heart and thymus. Results Small animal echocardiography revealed cardiac dysfunction even after 2 weeks of anti-PD-1 treatment, with distinct transcriptomic changes. Nitrosative stress was found to be elevated in the myocardium due to anti-PD-1 treatment, however, histological and qRT-PCR analysis did not reveal T cell infiltration into the myocardium and only mild inflammation was seen in the heart. In contrast, inflammatory gene expression was significantly enhanced in the thymus of anti-PD-1-treated animals, where interleukin-17 showed the most prominent increase. Conclusions These findings characterize cardiac dysfunction as a form of ICI-induced cardiotoxicity, which may be mediated by increased thymic inflammatory activation and cytokine production.

Background Cardiac cell lines and primary cells are widely used in cardiovascular research. Despite increasing number of publications using these models, comparative characterization of these cell lines has not been performed, therefore, their limitations are undetermined. We aimed to compare cardiac cell lines to primary cardiomyocytes and to mature cardiac tissues in a systematic manner. Methods and results Cardiac cell lines (H9C2, AC16, HL-1) were differentiated with widely used protocols. Left ventricular tissue, neonatal primary cardiomyocytes, and human induced pluripotent stem cell-derived cardiomyocytes served as reference tissue or cells. RNA expression of cardiac markers (e.g. Tnnt2, Ryr2) was markedly lower in cell lines compared to references. Differentiation induced increase in cardiac- and decrease in embryonic markers however, the overall transcriptomic profile and annotation to relevant biological processes showed consistently less pronounced cardiac phenotype in all cell lines in comparison to the corresponding references. Immunocytochemistry confirmed low expressions of structural protein sarcomeric alpha-actinin, troponin I and caveolin-3 in cell lines. Susceptibility of cell lines to sI/R injury in terms of viability as well as mitochondrial polarization differed from the primary cells irrespective of their degree of differentiation. Conclusion Expression patterns of cardiomyocyte markers and whole transcriptomic profile, as well as response to sI/R, and to hypertrophic stimuli indicate low-to-moderate similarity of cell lines to primary cells/cardiac tissues regardless their differentiation. Low resemblance of cell lines to mature adult cardiac tissue limits their potential use. Low translational value should be taken into account while choosing a particular cell line to model cardiomyocytes.

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – EU funding. Main funding source(s): Horizon 2020 research and innovation programme, Ministry for Innovation and Technology Background Dipeptidyl-peptidase-4 (DPP4) inhibitors are relatively new therapeutic tools for type 2 diabetes. The SAVOR-TIMI-53 clinical trial has revealed an increased heart failure (HF)-associated hospitalization rate in saxagliptin treated patients. Although this critical side effect could limit the therapeutic use considerably, the mechanism by which DPP4 inhibitors damage the heart is still unclear. Aims We aimed to set up a relevant cellular platform to investigate mechanistically DPP4 inhibition, and the role of its potentially important neuropeptide substrates (e.g. Substance P and Neuropeptide Y). Moreover, we aim to determine the expression of DDP4 and its neuropeptide substrates in human and cellular samples. Methods Western blot, ELISA, and radioimmunoassay experiments were performed to investigate the expression of DPP4 and its neuropeptide substrates in human hearts and in AC16 cells. Viability measurements with calcein staining and scratch assay experiments were used to test the potentially toxic effect of DPP4 inhibitors. The localization of DPP4 mRNA was determined with RNA Scope in situ hybridization. Results Expression of DPP4 and NPY proteins decreased in interventricular septum samples of patients with HF compared to healthy controls. In human hearts DPP4 mRNA is detectable in cardiomyocytes, while other cell types (endothelial cells, fibroblasts, and macrophages) show negligible expression. AC16 human cardiomyocyte cell line expresses DPP4 enzyme. Treatment with various DPP4 inhibitors administered alone or in combination with neuropeptides don’t affect cellular survival; although, in scratch assay experiments treatments with neuropeptides decreased cell migration speed in the isolated neonatal rat cardiomyocyte-fibroblast co-culture. The migration speed reducing effect of NPY was revered by the administration of saxagliptin at the highest concentration of NPY. Conclusions Decreased activity of DPP4 may play a role in the pathomechanism of end-stage congestive heart failure. The DPP4 enzyme could be important as a compensating mechanism against the elevated sympathetic activity in HF and for the altered neuropeptide tone. Inhibition of DPP4 could decrease this adaptive mechanism thereby exacerbating myocardial damage.