IL-6/gp130 signaling in CD4+ T cells drives the pathogenesis of pulmonary hypertension.

Pulmonary arterial hypertension (PAH) is characterized by stenosis and occlusions of small pulmonary arteries, leading to elevated pulmonary arterial pressure and right heart failure. Although accumulating evidence shows the importance of interleukin (IL)-6 in the pathogenesis of PAH, the target cells of IL-6 are poorly understood. Using mice harboring the floxed allele of gp130, a subunit of the IL-6 receptor, we found substantial Cre recombination in all hematopoietic cell lineages from the primitive hematopoietic stem cell level in SM22α-Cre mice. We also revealed that a CD4+ cell-specific gp130 deletion ameliorated the phenotype of hypoxia-induced pulmonary hypertension in mice. Disruption of IL-6 signaling via deletion of gp130 in CD4+ T cells inhibited phosphorylation of signal transducer and activator of transcription 3 (STAT3) and suppressed the hypoxia-induced increase in T helper 17 cells. To further examine the role of IL-6/gp130 signaling in more severe PH models, we developed Il6 knockout (KO) rats using the CRISPR/Cas9 system and showed that IL-6 deficiency could improve the pathophysiology in hypoxia-, monocrotaline-, and Sugen5416/hypoxia (SuHx)-induced rat PH models. Phosphorylation of STAT3 in CD4+ cells was also observed around the vascular lesions in the lungs of the SuHx rat model, but not in Il6 KO rats. Blockade of IL-6 signaling had an additive effect on conventional PAH therapeutics, such as endothelin receptor antagonist (macitentan) and soluble guanylyl cyclase stimulator (BAY41-2272). These findings suggest that IL-6/gp130 signaling in CD4+ cells plays a critical role in the pathogenesis of PAH.

Clinical and Histopathological Characteristics of Patients With Myocarditis After mRNA COVID-19 Vaccination.

BACKGROUND: The effects of myocarditis after mRNA COVID-19 vaccination (mCV) on myocardial tissue, and the association between cardiomyocyte injury and clinical presentation, are not fully understood. METHODS AND RESULTS: We retrospectively registered patients clinically diagnosed with myocarditis after the first or second mCV who underwent endomyocardial biopsy or autopsy from 42 participating centers in Japan. We investigated the histological features and their association with clinical presentation based on cardiomyocyte injury. Forty patients who underwent endomyocardial biopsy were included in the study. Of these, 19 (47.5%) showed mild lymphocytic infiltration and interstitial edema without cardiomyocyte injury. The remaining 21 (52.5%) patients showed cardiomyocyte injury accompanied by infiltrating inflammatory cells: 11 with lymphocytic infiltration, 7 with eosinophilic infiltration, and 3 with myocarditis with both lymphocyte and eosinophil infiltration. Compared with patients without cardiomyocyte injury, those with cardiomyocyte injury were clinically characterized by older age, a balanced sex distribution, less frequent chest pain, and a lower left ventricular ejection fraction. Fifteen of 21 (71.4%) patients with cardiomyocyte injury developed fulminant myocarditis, with 13 (86.7%) requiring mechanical circulatory support; in contrast, none of those without cardiomyocyte injury developed fulminant myocarditis (P<0.001). CONCLUSIONS: Our histological examination of patients with myocarditis after mCV revealed varying degrees of cardiomyocyte injury, ranging from pronounced to absent, along with various types of myocarditis. Cardiomyocyte injury was strongly associated with the severity of myocarditis.

Transthyretin derived amyloid deposits in the atrium and the aortic valve: insights from multimodality evaluations and mid-term follow up.

BACKGROUND: Recent studies have reported atrial involvement and coexistence of aortic stenosis in transthyretin (ATTR) cardiac amyloidosis (CA). However, pathological reports of extraventricular ATTR amyloid deposits in atrial structures or heart valves are limited, and the clinical implications of ATTR amyloid deposits outside the ventricles are not fully elucidated. CASE PRESENTATION: We report 3 cases of extraventricular ATTR amyloid deposits confirmed in surgically resected aortic valves and left atrial structures, all of which were unlikely to have significant ATTR amyloidosis infiltrating the ventricles as determined by multimodality evaluation including 99mtechnetium-pyrophosphate scintigraphy, cardiac magnetic resonance, endomyocardial biopsy and their mid-term clinical course up to 5 years. These findings suggested that these were extraventricular ATTR amyloid deposits localized in the aortic valve and the left atrium. CONCLUSIONS: While long-term observation is required to fully clarify whether these extraventricular ATTR amyloid deposits are truly localized outside the ventricles or are early stages of ATTR-CA infiltrating the ventricles, our 3 cases with multimodality evaluations and mid-term follow up suggest the existence of extraventricular ATTR amyloid deposits localized in the aortic valve and left atrial structures.

Myocardial T-Lymphocytes as a Prognostic Risk-Stratifying Marker of Dilated Cardiomyopathy　- Results of the Multicenter Registry to Investigate Inflammatory Cell Infiltration in Dilated Cardiomyopathy in Tissues of Endomyocardial Biopsy (INDICATE Study).

BACKGROUND: Dilated cardiomyopathy (DCM) associated with inflammation is diagnosed by endomyocardial biopsy; patients with this have a poorer prognosis than patients without inflammation. To date, standard diagnostic criteria have not been established.Methods and Results: This study analyzed clinical records and endomyocardial biopsy samples of 261 patients with DCM (201 males, median left ventricular ejection fraction; 28%) from 8 institutions in a multicenter retrospective study. Based on the European Society of Cardiology criteria and CD3 (T-lymphocytes) and CD68 (macrophages) immunohistochemistry, 48% of patients were categorized as having inflammatory DCM. For risk-stratification, we divided patients into 3 groups using Akaike Information Criterion/log-rank tests, which can determine multiple cut-off points: CD3+-Low, <13/mm2(n=178, 68%); CD3+-Moderate, 13-24/mm2(n=58, 22%); and CD3+-High, ≥24/mm2(n=25, 10%). The survival curves for cardiac death or left ventricular assist device implantation differed significantly among the 3 groups (10-year survival rates: CD3+-Low: 83.4%; CD3+-Moderate: 68.4%; CD3+-High: 21.1%; Log-rank P<0.001). Multivariate Cox analysis revealed CD3+count as a potent independent predictive factor for survival (fully adjusted hazard ratio: CD3+-High: 5.70, P<0.001; CD3+-Moderate: 2.64, P<0.01). CD3+-High was also associated with poor left ventricular functional and morphological recovery at short-term follow up. CONCLUSIONS: Myocardial CD3+T-lymphocyte infiltration has a significant prognostic impact in DCM and a 3-tiered risk-stratification model could be helpful to refine patient categorization.

Clinicopathologic Study of Placentas From Women With a Fontan Circulation.

BACKGROUND: Pregnant women with a Fontan circulation have a high risk of obstetric complications, such as preterm delivery and small for gestational age (SGA), which may be affected by low blood flow to the placenta and hypoxia. This study investigated placental pathology in a Fontan circulation.Methods and Results:Eighteen pregnancies in 11 women with a Fontan circulation were reviewed. Pregnancy outcomes showed 9 miscarriages and 9 live births, with 4 preterm deliveries. Five neonates were SGA (<5th percentile). Eight placentas from live births in 7 women were available for the study. Five placentas had low weight placenta for gestational age, and 7 grossly showed a chronic subchorionic hematoma. Histological examination revealed all placentas had some form of histological hypoxic lesions: maternal vascular malperfusion in 7, fetal vascular malperfusion in 1, and other hypoxia-related lesions in 8. Quantitative analyses, including immunohistochemistry (CD31, CD68, and hypoxia inducible factor-1α antibodies) and Masson's trichrome staining, were also performed and compared with 5 control placentas. Capillary density and the area of fibrosis were significantly greater in placentas from women with a Fontan circulation than in control placentas. CONCLUSIONS: Placentas in a Fontan circulation were characterized by a high frequency of low placental weight, chronic subchorionic hematoma, and constant histological hypoxic changes, which could reflect altered maternal cardiac conditions and lead to poor pregnancy outcomes.

Delayed diagnosis of dilated thyrotoxic cardiomyopathy with coexistent multifocal atrial tachycardia: a case report.

BACKGROUND: Thyroid storm (TS) is a rare but potentially life-threatening sequelae of untreated or undertreated hyperthyroidism. While TS frequently causes high-output heart failure, low-output heart failure related to dilated cardiomyopathy (DCM) is extremely rare. Tachycardia is a common clinical presentation of TS, and ß1-selective blockers are the first-line agents for treating TS-associated tachycardia. However, given that ß-blockers have negative chronotropic and negative inotropic effects, amiodarone may be safe and effective for the treatment of TS-induced tachyarrhythmia in patients with moderate to severe heart failure. While long-term amiodarone administration causes hypothyroidism, or less frequently, hyperthyroidism, little is known about the effects of short-term amiodarone administration on thyroid function. CASE PRESENTATION: A 31-year-old healthy woman presented with worsening dyspnoea. She was tachycardic with multifocal atrial tachycardia (MAT) of 184 beats/min, confirmed by electrocardiogram. Echocardiographic findings were consistent with DCM, with an ejection fraction of 20%. Thus, she was initially diagnosed with acute heart failure due to DCM with coexistent MAT. Tachycardia persisted despite cardioversion attempts and treatment with multiple anti-arrhythmic drugs. Consequently, she rapidly progressed to cardiogenic shock and respiratory decompensation, which required intubation and an intra-aortic balloon pump support. Moreover, the undiagnosed Graves' disease, lack of suspicion, and postponed analysis of thyroid function tests led to a delayed diagnosis of TS. Amiodarone, which was initiated for MAT, unexpectedly ameliorated thyrotoxicosis, resulting in a euthyroid state and the patient's significantly improved condition and cardiac function. She was discharged on day 40. Finally, she underwent total thyroidectomy; thyroid pathology was consisting with Graves' disease. Her postoperative course was uneventful. CONCLUSIONS: Herein, we describe a case of delayed diagnosis of dilated thyrotoxic cardiomyopathy with coexistent MAT. The patient required intensive care due to the catastrophic sequelae and was successfully treated with amiodarone. This is the first case report of TS-associated MAT and highlights the clinical importance of high suspicion of TS in de novo heart failure with any tachyarrhythmia or DCM of unknown etiology and the potential effects of short-term amiodarone administration in the treatment of TS.

Prognosis and Clinical Characteristics of Dilated Cardiomyopathy With Family History via Pedigree Analysis.

BACKGROUND: The clinical characteristics and prognostic outcomes of dilated cardiomyopathy (DCM) with a familial history (FHx) via pedigree analysis are unclear.Methods and Results:We conducted a prospective observational study of 514 consecutive Japanese patients with DCM. FHx was defined as the presence of DCM in ≥1 family member within 2-degrees relative based on pedigree analysis. The primary endpoint was a composite of major cardiac events (sudden cardiac death and pump failure death). The prevalence of FHx was 7.4% (n=38). During a median follow-up of 3.6 years, 77 (15%) patients experienced a major cardiac event. Multivariable Cox regression analysis identified FHx as independently associated with major cardiac events (hazard ratio [HR] 4.32; 95% confidence interval [CI], 2.04-9.19; P<0.001) compared with conventional risk factors such as age, QRS duration, and left ventricular volume. In the propensity score-matched cohort (n=38 each), the FHx group had a significantly higher incidence of major cardiac events (HR, 4.48; 95% CI, 1.25-16.13; P=0.022). In addition, the FHx group had a higher prevalence of a diffuse late gadolinium enhancement (LGE) pattern than the no-FHx group (32% vs. 17%, P=0.022). CONCLUSIONS: DCM patients with FHx had a worse prognosis, which was associated with a higher prevalence of a diffuse LGE pattern, than patients without FHx.

Pristane/Hypoxia (PriHx) Mouse as a Novel Model of Pulmonary Hypertension Reflecting Inflammation and Fibrosis.

BACKGROUND: Pulmonary arterial hypertension (PAH), particularly connective tissue disease-associated PAH (CTD-PAH), is a progressive disease and novel therapeutic agents based on the specific molecular pathogenesis are desired. In the pathogenesis of CTD-PAH, inflammation, immune cell abnormality, and fibrosis play important roles. However, the existing mouse pulmonary hypertension (PH) models do not reflect these features enough. The relationship between inflammation and hypoxia is still unclear.Methods and Results:Intraperitoneal administration of pristane, a kind of mineral oil, and exposure to chronic hypoxia were combined, and this model is referred to as pristane/hypoxia (PriHx) mice. Hemodynamic and histological analyses showed that the PriHx mice showed a more severe phenotype of PH than pristane or hypoxia alone. Immunohistological and flow cytometric analyses revealed infiltration of immune cells, including hemosiderin-laden macrophages and activated CD4+helper T lymphocytes in the lungs of PriHx mice. Pristane administration exacerbated lung fibrosis and elevated the expression of fibrosis-related genes. Inflammation-related genes such asIl6andCxcl2were also upregulated in the lungs of PriHx mice, and interleukin (IL)-6 blockade by monoclonal anti-IL-6 receptor antibody MR16-1 ameliorated PH of PriHx mice. CONCLUSIONS: A PriHx model, a novel mouse model of PH reflecting the pathological features of CTD-PAH, was developed through a combination of pristane administration and exposure to chronic hypoxia.

Significance and Value of Endomyocardial Biopsy Based on Our Own Experience.

Endomyocardial biopsy (EMB) has been established in parallel with the development of percutaneous catheter technology for the diagnosis of cardiac diseases. It was developed in the early 1960 s in Japan by Drs. Konno, Sakakibara and Sekiguchi of Tokyo Women's Medical University. EMB is a valuable and useful, but invasive, modality for making a definite diagnosis in diseases such as myocarditis and secondary cardiomyopathies, which are often difficult to diagnose by imaging modality alone. In the field of heart transplantation, the histology of EMB helps monitor rejection to allografts. In cases of chronic heart failure, fibrosis and degeneration of cardiomyocytes are very important findings of heart remodeling. Recently, molecular biology technology has been applied to EMB specimens to get more detailed information. However, we must also recognize that EMB is an invasive examination that should not be performed without skillful cardiac catheterization experience to avoid complications. In this review as a message from pathologists, we present key cardiac histopathology using EMB, in a way that allows one to imagine whole cardiac pathological conditions. We also describe the current role of EMB and its significance in order to encourage young cardiologists to perform EMB to see another world of pathology.

Late gadolinium enhancement in cardiac amyloidosis: attributable both to interstitial amyloid deposition and subendocardial fibrosis caused by ischemia.

Gadolinium contrast agents used for late gadolinium enhancement (LGE) distribute in the extracellular space. Global diffuse myocardial LGE pronounced in the subendocardial layers is common in cardiac amyloidosis. However, the pathophysiological basis of these findings has not been sufficiently explained. A 64-year-old man was admitted to our hospital with leg edema and nocturnal dyspnea. Bence Jones protein was positive in the urine, and an endomyocardial and skin biopsy showed light-chain (AL) amyloidosis. He died of ventricular fibrillation 3 months later. 9 days before death, the patient was examined by cardiac magnetic resonance (CMR) imaging on a 3-T system. We acquired LGE data at 2, 5, 10, and 20 min after the injection of gadolinium contrast agents, with a fixed inversion time of 350 ms. Myocardial LGE developed sequentially. The myocardium was diffusely enhanced at 2 min, except for the subendocardium, but LGE had extended to almost the entire left ventricle at 5 min and predominantly localized to the subendocardial region at 10 and 20 min. An autopsy revealed massive and diffused amyloid deposits in perimyocytes throughout the myocardium. Old and recent ischemic findings, such as replacement fibrosis and coagulative myocyte necrosis, were evident in the subendocardium. In the intramural coronary arteries, mild amyloid deposits were present within the subepicardial to the mid layer of the left ventricle, but no stenotic lesions were evident. However, capillaries were obstructed by amyloid deposits in the subendocardium. In conclusion, the late phase of dynamic LGE (at 10 and 20 min) visualized in the subendocardium corresponded to the interstitial amyloid deposition and subendocardial fibrosis caused by ischemia in our patient.

The importance of specialist cardiac histopathological examination in the investigation of young sudden cardiac deaths.

AIMS: Post-mortem examination of the heart in young sudden cardiac death (SCD) is vital as the underlying aetiology is often an inherited cardiac disease with implications for surviving relatives. Our aim is to demonstrate the improvement in diagnostic quality offered by a specialist cardiac pathology service established to investigate SCD with fast-track reporting on hearts sent by pathologists in cases of SCD. METHODS AND RESULTS: A tertiary centre prospective observational study was conducted. Detailed histopathological examination was performed in a tertiary centre specialized in the investigation of cardiac pathology in SCD. Hearts from 720 consecutive cases of SCD referred by coroners and pathologists from 2007 to 2009 were included. A comparison was drawn with diagnoses from referring pathologists. Most SCDs occurred in males (66%), with the median age being 32 years. The majority (57%) of deaths occurred at home. The main diagnoses were a morphologically normal heart (n = 321; 45%), cardiomyopathy (n = 207, 29%), and coronary artery pathology (n = 71; 10%). In 158 out of a sample of 200 consecutive cases, a cardiac examination was also performed by the referring pathologist with a disparity in diagnosis in 41% of the cases (κ = 0.48). Referring pathologists were more inclined to diagnose cardiomyopathy than normality with only 50 out of 80 (63%) normal hearts being described correctly. CONCLUSION: Expert cardiac pathology improves the accuracy of coronial post-mortem diagnoses in young SCD. This is important as the majority of cases may be due to inherited cardiac diseases and the autopsy guides the appropriate cardiological evaluation of blood relatives for their risk of sudden death.

The pathological implications of heart transplantation: experience with 50 cases in a single center.

Heart transplantation started in Japan in 1999. Since then, 50 transplants have been performed at our center. We performed histopathological analyses of the 50 explanted hearts and the post-transplant biopsy specimens. The median age of recipients was 39 years. The primary diseases before transplant were idiopathic dilated cardiomyopathy in 33 patients (66%), hypertrophic cardiomyopathy in seven (14%), restrictive cardiomyopathy in one, arrhythmogenic right ventricular cardiomyopathy in one, and secondary cardiomyopathy in eight (16%). Before transplantation, 47 patients (94%) had left ventricular assist devices. No severe cardiovascular failure due to allograft rejection occurred. The post-transplant survival rate was 97.6% at 1 year and 93.1% at 10 years. One recipient was lost to sepsis from myelodysplastic syndrome in the fourth year, one died of multiple organ failure and peritonitis 8 months after transplant. Another patient died of recurrent post-transplant lymphoproliferative disorders (PTLD). Mild cardiac dysfunction occurred in seven recipients in the early postoperative period. Moderate acute cellular rejection occurred in six patients (12%), and antibody-mediated rejection occurred in three (6%). The number of heart transplants performed in Japan is very small. However, the outstanding 10-year survival rate is due to donor evaluation and post-transplant care resulting in low grade rejection. Pathological evaluation has also greatly contributed to the results.

Giant cell myocarditis attributable to myositis: therapeutic management under the guidance of serial endomyocardial biopsy-a case report.

Background: Giant cell myocarditis is a fatal disease that could be rapidly progressive if not properly managed. However, the role of immunosuppressive therapy, especially in refractory cases, remains unclear. Case summary: A 76-year-old man presented with back pain with elevated cardiac enzymes. Skeletal muscle and endomyocardial biopsies revealed giant cell myositis and giant cell myocarditis. Despite the initial immunosuppressive therapy, cardiac enzymes continued to rise. Serial endomyocardial biopsies enabled combination treatment of prednisolone, cyclosporine, and mycophenolate mofetil according to histological inflammatory activity. Discussion: We presented a case of refractory giant cell myocarditis preceded by giant cell myositis. While endomyocardial biopsy is an approach with risk of procedural complications, it can guide giant cell myocarditis management when the initial immunosuppressive therapy is ineffective.

Case series: successful salvage from refractory cardiogenic shock caused by COVID-19-associated myocardial injury with temporary ventricular assist devices.

Background: Coronavirus disease 2019 (COVID-19) is predominantly known to cause respiratory injury; however, the present case series highlights four instances in which the infection resulted in significant cardiac complications. Among such cases, some represent severe cardiogenic shock, which necessitates the immediate introduction of mechanical circulatory support (MCS) for salvage. Case summary: This case series involved patients with COVID-19-associated myocardial injury leading to fulminant cardiogenic shock. These patients required immediate implementation of peripheral MCS, followed by an instant upgrade to a central MCS system due to anatomical limitations and severe biventricular dysfunction. Central MCS provided effective ventricular unloading, resulting in a significant and prompt improvement in ventricular function. The treatment timeline showed rapid deterioration followed by remarkable recovery within 2 weeks of MCS initiation, demonstrating the effectiveness of aggressive and tailored MCS strategies in managing severe COVID-19-related cardiac complications. Discussion: This study provides significant insights into the cardiovascular implications of COVID-19, particularly in the context of severe myocardial injury that leads to cardiogenic shock. The report underscores the importance of early recognition and intervention in such cases, focusing on the use of MCS as a life-saving modality. The findings also revealed unique pathological features of COVID-19-associated myocardial injury, including macrophage-predominant infiltration and microthrombosis, which are distinct from the features of conventional myocarditis. These findings highlight the need for further research on the pathophysiology of COVID-19-related cardiac injuries and the development of targeted therapeutic strategies.

Suppressing the expression of steroidogenic acute regulatory protein (StAR) in the myocardium by spironolactone contributes to the improvement of right ventricular remodeling in pulmonary arterial hypertension.

Pulmonary arterial hypertension (PAH) is a progressive condition that frequently leads to right ventricular (RV) remodeling. Aldosterone promotes vascular and RV remodeling. The upregulation of steroidogenic acute regulatory protein (StAR) stimulates aldosterone synthesis. However, the expression of StAR in the myocardium under PAH conditions remains unknown. To investigate the expression of StAR in the myocardium and its association with RV remodeling in PAH, utilizing spironolactone as a treatment. A PAH model was created using male Sprague-Dawley rats, which received a subcutaneous injection of Sugen5416 (20 mg/kg) and were exposed to hypoxia (10% O2) for 2 weeks, followed by 2 weeks of normoxia. The animals were then divided into two groups, with one group receiving spironolactone (25 mg/kg/day) for an additional 4 weeks, while the other group did not. H9c2 cells were cultured under hypoxic conditions (37 °C, 1% O2, 5% CO2) with or without spironolactone treatment. In the model rats, RV systolic pressure and the Fulton index, both of which increased upon exposure to Sugen5416 and hypoxia, significantly decreased with spironolactone treatment. In H9c2 cells, hypoxic exposure elevated aldosterone levels, while spironolactone treatment significantly suppressed aldosterone production. Suppression of StAR expression in the myocardium via spironolactone contributes to the improvement of RV remodeling in PAH. Spironolactone may offer a valuable therapeutic strategy for RV remodeling in patients with PAH.

Can right ventricular endomyocardial biopsy predict left ventricular fibrosis beforehand in dilated cardiomyopathy?

AIMS: Myocardial fibrosis of the left ventricle (LV) is a prognostic factor in dilated cardiomyopathy (DCM). This study aims to evaluate whether fibrosis of right ventricular (RV) endomyocardial biopsy (EMB) can predict the degree of LV fibrosis beforehand in DCM. METHODS AND RESULTS: Fibrosis extent in 70 RV-EMB specimens of DCM diagnosis was compared with that in the whole cross-sectional LV of excised hearts in the same patients (52 explanted hearts for transplant and 18 autopsied hearts). The median interval between biopsy and excision was 4.1 (0.13-19.3) years. The fibrosis area ratio of the EMBs and excised hearts were evaluated via image analysis. The distribution of cardiovascular magnetic resonance-late gadolinium enhancement (LGE) in the intraventricular septum was classified into four quartile categories. The fibrosis area ratio in RV-EMB correlated significantly with that in the short-axis cut of the LV of excised hearts (r = 0.82, P < 0.0001) and with a diffuse pattern of LGE (r = 0.71, P = 0.003). In a multivariate model, after adjusting for the interval between biopsy performance and heart excision, the fibrosis area ratio in RV-EMB was associated with that in LV-excised heart (regression coefficient, 0.82; 95% confidence interval, 0.68-0.95; P < 0.0001). CONCLUSIONS: The fibrosis observed in RV-EMB positively correlated with the extent of fibrosis in the LV of excised hearts in patients with DCM. The study findings may help predict LV fibrosis, considered a prognostic factor of DCM through relatively accessible biopsy techniques.