Histological evidence of concomitant intramyocardial and epicardial vasculitis in necropsied heart allografts: a possible relationship with graft coronary arteriosclerosis

Intragraft vasculitis and gene expression analysis: Association with acute rejection and prediction of mortality in long-term heart transplantation

INTRODUCTION

Vasculitis entails heterogeneous origins; it starts with an inflammatory process that leads to small vessels' necrosis, hemorrhage, and ischemic lesion, and may further result in occlusion of the vascular lumen. Vasculitis' contribution to allograft rejection is still unclear. This study aims to investigate the incidence of vasculitis in the early stages of heart transplantation as well as to assess the intragraft genes' expression associated with vascular function and subsequently to verify the way in which it affects the outcome of the allograft.

METHODS

In this retrospective study, 300 archive paraffin-embedded endomyocardial biopsies from 63 heart allograft recipients were assessed. Cellular rejection and vasculitis were diagnosed through histological analysis, and antibody-mediated rejection was performed with immunohistochemical C4d staining. The transcripts of ICAM, VCAM, VEGF, CCL2, IFNG, TGFB, TNF, ADIPOR1, and ADIPOR2 genes were examined through quantitative polymerase chain reaction using B2M for normalization.

RESULTS

We observed a higher prevalence of severe vasculitis in the early period of post-transplant, and recovery was observed to take place around 1 year post-transplant. Additionally, vasculitis was found to be directly associated with acute cellular rejection and antibody-mediated rejection. The intense C4d capillary positivity predicts higher long-term cardiovascular disease mortality. In comparison with the vasculitis-free group, the group with severe vasculitis displayed reduced left ventricular ejection fraction and an upregulation of VCAM and IFNG associated with the downregulation of VEGF, ADIPOR1, and ADIPOR2.

CONCLUSION

The vasculitis associated with the presence of C4d and the change in intragraft gene expression profile may contribute to poor allograft outcomes.

Comparison Between Cardiac Allograft Vasculopathy and Native Coronary Atherosclerosis by Optical Coherence Tomography

We sought to explore differences in distribution and morphology of coronary lesions comparing cardiac allograft vasculopathy and native coronary atherosclerosis (NCA) using intravascular imaging with optical coherence tomography (OCT). At the time of routine surveillance angiography, 17 heart transplant (HT) recipients with a history of high-grade cellular rejection (HGR) and 43 HT recipients with none/mild (low)-grade rejection underwent OCT imaging of the left anterior descending and were compared to 60 patients with NCA without HT. Compared with patients with NCA, patients with HGR had similar intima areas but smaller external elastic lamina areas (7.9 mm(2) [6.3, 11.2] versus 6.6 mm(2) [4.8, 7.5], p = 0.02) resulting in smaller lumen areas (4.5 mm(2) [3.4, 6.6] versus 3.3 mm(2) [2.8, 4.7], p = 0.04) in distal segments and smaller lumen diameters in side branches (1.28 mm [1.19, 1.37] versus 1.09 mm [0.94, 1.24], p = 0.04). Compared with patients with NCA, lesions in patients with HT were more homogeneous, involving the entire coronary vascular tree. Patients with HGR had a higher prevalence of macrophages involving ≥1 quadrant in all 3 segments compared with patients with NCA. The number of microvessels was greater in patients with both HGR and LGR HT versus NCA. In conclusion, distinct findings in the distribution and morphology of coronary lesions between HT recipients and patients with NCA are evident by OCT imaging, suggesting that OCT might be useful to help differentiate cardiac allograft vasculopathy from NCA in vivo.

A case report of lethal post-viral lymphocytic myocarditis with exclusive location in the right ventricle

The inflammatory involvement of vital organs may represent a dangerous and life-threatening situation: in particular, the inflammation of the myocardial tissue of the heart may lead to severe consequences since the clinical history of the disease may be completely asymptomatic, any clinical sign may be lacking, thus preventing correct diagnosis and treatment. This may occur even in the case of myocarditis and may lead to unexpected death whose cause can be assessable only by means of a thorough histopathological examination. The article reports the case of 61-year old female who developed a flu-like syndrome with very few symptoms, followed by sudden death in three weeks. The autopsy and following histopathological investigations identified the cause of death in a post-viral lymphocytic myocarditis, probably related to the previous infectious disease, and alternative causes (as arrhythmic ventricular dysplasia, vasculitis, sarcoidosis and giant cell myocarditis) were excluded. The exclusive location in the right ventricle was a peculiar finding. The case highlights the importance of the myocardium of the right ventricle, a tissue which is often less considered even in histopathological surveys. The exclusive location of myocarditis in the right ventricle is a rare event but in this case fully responsible for death.

Clinico-pathologic findings in end-stage pediatric heart transplant grafts

The pathologic patterns existing in end-stage pediatric heart transplant grafts may help explain the symptoms and changes seen by echocardiography and angiography in these children. Retrospective chart review and pathologic study of explanted heart grafts was performed on 12 patients that had undergone 14 heart re-transplantations. Clinical status, echocardiographic and catheterization data at the time of transplantation were correlated to the pathologic findings. At re-OHT, eight were inpatients with heart failure symptoms and/or inotropic support requirements. Echocardiograms were abnormal in all prior to re-OHT with significant diastolic dysfunction, but LVEF >40% in all but one. There was significant epicardial fibrosis in all grafts, and all had severe CAV of epicardial arteries. However, intramyocardial coronary disease was mild in nine (64%) grafts. Moderate or severe interstitial fibrosis occurred in only three grafts, and in a perivascular distribution in eight. End-stage pediatric heart allografts have severe epicardial CAV and epicardial fibrosis, with relative sparing of the myocardium. Epicardial disease with sparing of the myocardium may explain the restrictive hemodynamics and relatively preserved systolic function present in these grafts at the time of re-OHT.

Inflammatory burden of cardiac allograft coronary atherosclerotic plaque is associated with early recurrent cellular rejection and predicts a higher risk of vasculopathy progression

OBJECTIVES

This study was designed to investigate tissue characterization of the coronary allograft atherosclerotic plaque with virtual histology intravascular ultrasound (VH-IVUS) imaging to assess the presence and predictors of vessel wall inflammation and its significance in cardiac allograft vasculopathy (CAV) progression.

BACKGROUND

A unique form of accelerated atherosclerosis, CAV remains the leading cause of late morbidity and mortality in heart transplant patients. The pathogenesis of CAV is not fully elucidated.

METHODS

A total of 86 patients with coronary allograft vasculopathy underwent VH-IVUS examination of the left anterior descending coronary artery 3.61 +/- 3.04 years following cardiac transplantation. Based on the VH-IVUS plaque characteristics, coronary allograft plaque was divided on virtual histology intravascular ultrasound-derived "inflammatory" (VHD-IP) (necrotic core and dense calcium > or =30%) and "noninflammatory" plaque (VHD-NIP) (necrotic core and dense calcium <30%). Total rejection scores were calculated based on the 2004 International Society of Heart and Lung Transplantation rejection grading system.

RESULTS

In the whole study population, the mean percentage of fibrous, fibrofatty, dense calcified, and necrotic core plaques in a mean length of 62.3 +/- 17.4 mm of the left anterior descending coronary artery were 50 +/- 17%, 16 +/- 11%, 15 +/- 11%, and 18 +/- 9%, respectively. Patients with a 6-month total rejection score >0.3 had significantly higher incidence of VHD-IP than those with a 6-month total rejection score < or =0.3 (69% vs. 33%, p = 0.011). The presence of VHD-IP at baseline was associated with a significant increase in plaque volume (2.42 +/- 1.78 mm(3)/mm vs. -0.11 +/- 1.65 mm(3)/mm, p = 0.010), plaque index (7 +/- 9% vs. 0 +/- 8%, p = 0.04), and remodeling index (1.24 +/- 0.44 vs. 1.09 +/- 0.36, p = 0.030) during 12 months of follow-up when compared with the presence of VHD-NIP at baseline and during follow-up.

CONCLUSIONS

The presence of VHD-IP as assessed by VH-IVUS is associated with early recurrent rejection and with higher subsequent progression of CAV. A VH-IVUS assessment may add important information in the evaluation of transplant recipients.

Cardiac allograft vasculopathy and insulin resistance--hope for new therapeutic targets

Cardiac allograft vasculopathy (CAV) is a major cause of death in patients surviving more than 1 year after heart transplantation. An important cluster of CAV risk factors occurs as a consequence of insulin resistance and manifests as part of the metabolic syndrome. This article summarizes the pathologic features of CAV and reviews the contribution of the major components of insulin resistance in CAV development and progression. It focuses on the few studies that have analyzed the impact of the individual metabolic abnormalities and inflammation and on therapeutic strategies to minimize the clinical manifestation of insulin resistance after heart transplantation.

Cardiac allograft vasculopathy and insulin resistance--hope for new therapeutic targets

Cardiac allograft vasculopathy (CAV) is a major cause of death in patients surviving more than 1 year after heart transplantation. An important cluster of CAV risk factors occurs as a consequence of insulin resistance and manifests as part of the metabolic syndrome. This article summarizes the pathologic features of CAV and reviews the contribution of the major components of insulin resistance in CAV development and progression. It focuses on the few studies that have analyzed the impact of the individual metabolic abnormalities and inflammation and on therapeutic strategies to minimize the clinical manifestation of insulin resistance after heart transplantation.

Extensive cardiac allograft vasculitis and concurrent fat necrosis 6 years after orthotopic heart transplantation

Coronary artery vasculitis has been described as a rare lesion in the spectrum of transplant vasculopathy or as an extension of severe acute cellular rejection. We describe a patient, 6 years after orthotopic cardiac transplantation, who developed rapid heart failure and died despite aggressive treatment, minimal cardiac rejection (ISHLT Grade 1R), and no known transplant vasculopathy. Autopsy showed a diffuse and essentially complete necrotizing vasculitis of the entire coronary vasculature involving small, medium and large vessels, with extensive fat necrosis within the pericardial space. Macrophages of the M2 phenotype were found lining the major coronary vascular lumens and infiltrating their walls. The presence of the M2 macrophage phenotype supports transplant vasculitis as part of the chronic transplant vasculopathy continuum.

Update on cardiac transplantation pathology

CONTEXT

The endomyocardial biopsy is the mainstay for monitoring acute allograft rejection in heart transplantation. Objective and accurate assessment of cellular and humoral types of rejection is important to optimize immunosuppressive therapy, avoid therapeutic complications, and improve patient outcome. The grading system for evaluation of heart transplant biopsies published in 1990 was revised in 2004 after more than a decade of implementation.

OBJECTIVE

In this review, we focus on a practical approach to the evaluation of human heart transplant biopsies as diagnostic surgical pathologic specimens. We discuss the revised International Society of Heart and Lung Transplantation working formulation.

DATA SOURCES

We reviewed pertinent literature, incorporating ideas and vast experience of participants in various work groups that led to the revision of the 1990 grading system.

CONCLUSIONS

The grading system for cellular rejection is presented with detailed light microscopic morphology and comparison of the 1990 and 2004 International Society of Heart and Lung Transplantation working formulations. We show how the pathologic recognition of cellular rejection and antibody-mediated rejection has evolved. We emphasize the interpretation of immunostains for complement components C4d and C3d in the diagnosis of antibody-mediated rejection. Evidence of regulation of complement activation in human heart transplant biopsies is presented in this context. We also discuss the pitfalls, caveats, and artifacts in the interpretation of allograft endomyocardial biopsies. Lastly, we discuss the pathology of human cardiac allograft vasculopathy in practical detail.

Graft Vascular Disease After Cardiac Transplantation and Its Relationship to Mean Acute Rejection Score

Context.—Graft vascular disease remains a significant source of morbidity and mortality in heart transplant patients. The influence of acute cellular rejection on the development of graft vascular disease is controversial.

Objective.—To determine the relationship between mean acute cellular rejection score and the presence of atherosclerosis or fibrointimal hyperplasia in cardiac allografts at autopsy.

Design.—This retrospective, autopsy-based study examined 27 heart transplant patients to evaluate for graft vascular disease. A rejection score for each patient was calculated as the average of all the rejection scores determined by endomyocardial biopsy. Gross and histologic examination of the heart was used to divide patients into 3 groups: no coronary artery disease, atherosclerosis, and fibrointimal hyperplasia. Mean rejection scores were calculated for each of these groups for all patients and patients who survived longer than 3 months. Mean rejection scores were compared by an analysis of variance and pairwise t tests.

Results.—Mean rejection scores demonstrated a trend of increasing value from no coronary disease (0.323) to atherosclerosis (0.569) to fibrointimal hyperplasia (0.835). Only fibrointimal hyperplasia had a significantly higher mean rejection score compared with patients with no coronary disease when examined in all patients (P = .01) and in patients who survived longer than 3 months (P = .049).

Conclusion.—This study showed that the development of coronary artery fibrointimal hyperplasia, but not atherosclerosis, was significantly related to mean acute rejection score.

Neointimal smooth muscle cells in human cardiac allograft coronary artery vasculopathy are of donor origin

BACKGROUND

Transplant coronary artery vasculopathy (CAV) is a fibro-proliferative process that leads to lumen occlusion and cardiac failure. Current theories suggest that the process evolves over time in response to inflammation and proliferation of donor derived medial smooth muscle cells (SMC). Animal models of cardiac transplantation have suggested that the neointima is formed by recipient derived circulating progenitor cells. The aim of this investigation is to determine the origin of the neointimal SMC within epicardial coronary arteries from human cardiac allografts by using sex mis-matched recipients and donors, and a Y specific chromosome probe.

METHODS

Coronary arteries from 14 patients previously assessed histologically to have CAV were analyzed-eight male recipients of female donor organs, 2 female-to-female, and 4 male-to-male transplants. A double immunocytochemistry and in-situ hybridization technique using a Y chromosome DNA probe and either antibodies to smooth muscle actin or Ham-56 a macrophage marker were employed.

RESULTS

No Y chromosome bodies could be identified in the female-to-female allografts. In the 4 male donor and male recipient cases, cells positive for the Y chromosome probe were identified. In sex mis-matched transplants, female to male, inflammatory cells marked with Ham-56 were also positive for Y chromosome probe. Flattened cells positive for Y chromosome were observed just beneath the endothelial surface. When double stained, these were identified as infiltrating macrophages. No double staining smooth muscle cells and Y chromosome positive cells could be identified within the neointima.

CONCLUSIONS

This study confirms the source of SMC of the neointima of CAV lesions from epicardial coronary arteries to be of donor origin. In contrast to animal models, circulating progenitor cells do not appear to play a role within the neointima of human transplant CAV.