simultaneous-3d-analysis-cardiac-damage-immune-response-reperfused

Simultaneous 3D Analysis of Cardiac Damage and Immune Response in Reperfused Acute Myocardial Infarction Using Light Sheet Fluorescence Microscopy

Complex cellular interactions determine functional and structural tissue remodeling during reperfused acute myocardial infarction (repAMI). These ...

University Hospital Essen

Cancer survival rates have increased significantly because of improvements in therapy regimes and novel immunomodulatory drugs. Recently, combination therapies of anthracyclines and immune checkpoint inhibitors (ICIs) have been proposed to maximize neoplastic cell removal. However, it has been speculated that a priori anthracycline exposure may prone the heart vulnerable to increased toxicity from subsequent ICI therapy, such as an anti-programmed cell death protein 1 (PD1) inhibitor. Here, we used a high-dose anthracycline mouse model to characterize the role of the PD1 immune checkpoint signaling pathway in cardiac tissue using flow cytometry and immunostaining. Anthracycline treatment led to decreased heart function, increased concentration of markers of cell death after six days and a change in heart cell population composition with fewer cardiomyocytes. At the same time point, the number of PD1 ligand (PDL1)-positive immune cells and endothelial cells in the heart decreased significantly. The results suggest that PD1/PDL1 signaling is affected after anthracycline treatment, which may contribute to an increased susceptibility to immune-related adverse events of subsequent anti-PD1/PDL1 cancer therapy.

Anthracycline Therapy Modifies Immune Checkpoint Signaling in the Heart.

CD47 is a cell surface protein controlling phagocytotic activity of innate immune cells. CD47 blockade was investigated as an immune checkpoint therapy in cancer treatment, enhancing phagocytosis of tumor cells by macrophages. Anti-CD47 treatment also reduced injury size during reperfused acute myocardial infarction (repAMI) by enhancing phagocytotic acitivity of macrophages. Little is known about the impact of CD47 blockade on neutrophils, representing the main portion of early infiltrating immune cells after repAMI. Therefore, we performed 45 min of cardiac ischemia followed by 24 h of reperfusion, observing a decreased cardiac injury size measured by triphenyl tetrazolium chloride (TTC) Evan's blue staining. We were able to detect this effect with an innovative three-dimensional method based on light sheet fluorescence microscopy (LSFM). This further allowed us a simultaneous analysis of neutrophil infiltration, showing an unaltered amount of injury-associated neutrophils with reduced cardiac injury volume from repAMI. This observation suggests modulated phagocytosis of cell debris by neutrophils. Therefore, we performed flow cytometry analysis, revealing an increased phagocytotic activity of neutrophils . These findings highlight that CD47 blockade also enhances phagocytosis of cardiac cell debris by neutrophils, which might be an additional protective effect of anti-CD47 treatment after repAMI.

CD47 blockade enhances phagocytosis of cardiac cell debris by neutrophils.

Cancer therapy-related cardiovascular toxicity (CTR-CVT) from immune checkpoint inhibitor (ICI) therapy is still incompletely characterized, and patients with pre-existing cardiovascular disease represent a particularly high-risk cohort. Valid parameters for risk stratification of these patients are missing. Neutrophil-to-lymphocyte ratio (NLR) has been shown to predict mortality and adverse events in other cardiovascular cohorts. The present study aims to examine the predictive capacity of NLR for risk stratification of patients particularly vulnerable for CTR-CVT under ICI therapy.

High neutrophil-to-lymphocyte ratio is associated with cancer therapy-related cardiovascular toxicity in high-risk cancer patients under immune checkpoint inhibitor therapy.

Post-injury dysfunction of humoral immunity accounts for infections and poor outcomes in cardiovascular diseases. Among immunoglobulins (Ig), IgA, the most abundant mucosal antibody, is produced by plasma B cells in intestinal Peyer's patches (PP) and lamina propria. Here we show that patients with stroke and myocardial ischemia (MI) had strongly reduced IgA blood levels. This was phenocopied in experimental mouse models where decreased plasma and fecal IgA were accompanied by rapid loss of IgA-producing plasma cells in PP and lamina propria. Reduced plasma IgG was detectable in patients and experimental mice 3-10 d after injury. Stroke/MI triggered the release of neutrophil extracellular traps (NETs). Depletion of neutrophils, NET degradation or blockade of NET release inhibited the loss of IgA cells and circulating IgA in experimental stroke and MI and in patients with stroke. Our results unveil how tissue-injury-triggered systemic NET release disrupts physiological Ig secretion and how this can be inhibited in patients.

Stroke and myocardial infarction induce neutrophil extracellular trap release disrupting lymphoid organ structure and immunoglobulin secretion.

Introduction of modern cancer therapies has led to increased survival of affected patients. With this advantage, the incidence of cancer therapy-related cardiac dysfunction (CTRCD) has increased and reasonable prevention strategies become necessary. This review outlines the major approaches to limit development and progression of CTRCD.

Prevention of cancer-therapy related cardiac dysfunction.

Low hemoglobin values are associated with cardiotoxicity in patients with melanoma and other cancer entities receiving immune checkpoint inhibitor (ICI) therapy. However, in cancer patients under chemotherapy, enhanced incidence of cardiotoxicity events are also reported with increasing hemoglobin values. So far, the association between hemoglobin values within the normal limits and the incidence of cardiotoxicity in melanoma patients treated with ICI therapy has not been examined.

Hemoglobin is associated with cardiotoxicity in melanoma patients without anemia receiving immune checkpoint inhibitor therapy.

Reactive fibrosis is a complex response to chronic myocardial insults, contributing to heart failure progression. Fibroblast activation protein inhibitor (FAPI) PET shows promise in distinguishing active from established fibrosis. Although antifibrotic therapies may improve left ventricular (LV) function in preclinical studies, their clinical application is limited by the lack of noninvasive imaging methods to assess fibrosis regression. This study investigates the potential of FAPI PET to track the therapeutic transition of activated fibroblast activation protein (FAP)-positive fibroblasts toward a FAP-negative phenotype.  Mice were implanted with minipumps, infused with angiotensin-II/phenylephrine (Ang-II/PE) for 6 wk and scanned with Ga-FAPI-46 PET/CT longitudinally. Control mice received saline. Ga-FAPI-46 biodistribution studies were conducted at preselected time points, and FAPI uptake in the major organs was measured ex vivo. To assess the potential reversibility of the FAPI PET signal in the myocardium and liver, Ang-II/PE infusion was discontinued in a group of animals at 1 and 2 wk, respectively. LV structural and functional changes were assessed via echocardiography, tissue fibrosis via histology, and FAP expression via immunohistochemistry.  Significant Ga-FAPI-46 uptake in the myocardium of treated mice peaked at 1 wk. An increase of Ga-FAPI-46 uptake was also observed in the liver, peaking at 2 wk, and decreased significantly at 4 wk. The PET signal declined to an indiscernible level in the heart and liver early after Ang-II/PE withdrawal. Three weeks after the removal of the minipumps, the hearts of mice previously exposed to Ang-II/PE for 1 wk exhibited a significant reduction in fibrosis compared with mice that were sacrificed immediately after 1 wk of Ang-II/PE infusion, without the 3-wk recovery period. Coinjection with excess unlabeled FAPI-46 reduced uptake in the heart, liver, and kidneys. Despite an increase in LV wall thickness at 1 wk, the ejection fraction remained stable initially but dropped significantly by 4 wk.  The rapid decline in PET signal after Ang-II/PE withdrawal shows that FAPI PET effectively visualizes dynamic changes in FAP expression, making it a valuable tool for quickly assessing treatment responses targeting activated fibroblasts. The cardiac FAPI signal precedes functional myocardial changes, indicating that FAPI PET could detect early fibrosis in cardiac remodeling leading to heart failure. FAPI PET may also visualize cardiac cirrhosis, a serious complication of cardiac disorders.

Article	Year
Anthracycline Therapy Modifies Immune Checkpoint Signaling in the Heart. International journal of molecular sciences\| PubMed ID: 37047026	2023
CD47 blockade enhances phagocytosis of cardiac cell debris by neutrophils. International journal of cardiology. Heart & vasculature\| PubMed ID: 37731517	2023
High neutrophil-to-lymphocyte ratio is associated with cancer therapy-related cardiovascular toxicity in high-risk cancer patients under immune checkpoint inhibitor therapy. Clinical research in cardiology : official journal of the German Cardiac Society\| PubMed ID: 37955712	2024
Stroke and myocardial infarction induce neutrophil extracellular trap release disrupting lymphoid organ structure and immunoglobulin secretion. Nature cardiovascular research\| PubMed ID: 39195931	2024
Prevention of cancer-therapy related cardiac dysfunction. Current heart failure reports\| PubMed ID: 39969700	2025
Hemoglobin is associated with cardiotoxicity in melanoma patients without anemia receiving immune checkpoint inhibitor therapy. International journal of cardiology. Heart & vasculature\| PubMed ID: 40851558	2025
How Rapidly Does the FAPI PET Signal Reverse Following Therapy? Assessing the FAPI PET Signal in Hypertensive Cardiac Injury and Fibrosis in Mice. Journal of nuclear medicine : official publication, Society of Nuclear Medicine\| PubMed ID: 40935615	2025

Elias Haj-Yehia

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