[show abstract][hide abstract] ABSTRACT: During the last 25 years, antibody-mediated rejection of the cardiac allograft has evolved from a relatively obscure concept to a recognized clinical complication in the management of heart transplant patients. Herein we report the consensus findings from a series of meetings held between 2010-2012 to develop a Working Formulation for the pathologic diagnosis, grading, and reporting of cardiac antibody-mediated rejection. The diagnostic criteria for its morphologic and immunopathologic components are enumerated, illustrated, and described in detail. Numerous challenges and unresolved clinical, immunologic, and pathologic questions remain to which a Working Formulation may facilitate answers.
The Journal of heart and lung transplantation: the official publication of the International Society for Heart Transplantation 12/2013; 32(12):1147-1162. · 3.54 Impact Factor
[show abstract][hide abstract] ABSTRACT: Pulmonary endothelial injury triggers a reparative program, which in susceptible individuals is characterized by neointima formation, vascular narrowing and the development of pulmonary arterial hypertension. The neointimal cells in human pathologic plexiform lesions frequently coexpress smooth muscle alpha-actin and the endothelial von Willebrand antigen, creating a question about their cellular lineage of origin.
Experimental pulmonary hypertension with neointima formation develops in C57Bl/6 mice subjected to left pneumonectomy followed one week later by jugular vein injection of monocrotaline pyrrole (20µg/µl)(1µl/g) (Group P/MCTP). Compared to Group Vehicle, by Day 35, Group P/MCTP developed higher right ventricular systolic pressure (54 ± 5 vs. 25 ± 2 mmHg, p < 0.01) and right ventricular hypertrophy (0.58 ± 0.16 vs. 0.26 ± 0.05, p < 0.01). Transgenic Vascular Endothelial-Cadherin (VE-Cad) Cre recombinase or Tie-2 Cre mice were intercrossed with mTomato/mGFP double fluorescent Cre reporter mice to achieve endothelial genetic lineage marking with membrane-targeted GFP. In control mice, few endothelial lineage-marked cells lining the lumen of small pulmonary arteries demonstrate expression of smooth muscle α-actin (SMA). Concurrent with the development of pulmonary hypertension, endothelial lineage-marked cells are prominent in the neointima and exhibit expression of SMA and smooth muscle myosin heavy chain (SM-MHC). Human pulmonary arterial hypertension neointimal lesions contain cells that coexpress endothelial CD31 or von Willebrand antigen, and SMA.
Neointimal cells in pulmonary hypertension include contributions from the endothelial genetic lineage with induced expression of SMA and SM-MHC.
[show abstract][hide abstract] ABSTRACT: HC is a rare cause of congestive heart failure that typically presents with malignant ventricular arrhythmias in infants, often requiring urgent intervention. Successful heart transplantation in a patient with HC has only been reported once (J Heart Lung Transplant 2004: 23: 902). The combination of HC with concurrent LVNC has only been described three times (Int J Legal Med 2009: 123: 47; Hum Pathol 2005: 36: 403; Pediatr Dev Pathol 2012: 15: 397). We report two rare cases of HC with LVNC in two infants presenting with cardiogenic shock, one requiring ECMO support who was successfully bridged to orthotopic heart transplantation with a Berlin Heart LVAD.
[show abstract][hide abstract] ABSTRACT: Primary cardiac paragangliomas are rare extra-adrenal tumors. Though they account for less than 1% of all primary cardiac tumors, they are considerable sources of morbidity and mortality. In this case review, we discuss the challenges associated with the diagnosis and management of cardiac paragangliomas.
Journal of Cardiac Surgery 01/2012; 27(2):178-82. · 1.35 Impact Factor
[show abstract][hide abstract] ABSTRACT: Marfan syndrome (MFS) is a systemic connective tissue disorder notable for the development of aortic root aneurysms and the subsequent life-threatening complications of aortic dissection and rupture. Underlying fibrillin-1 gene mutations cause increased transforming growth factor-β (TGF-β) signaling. Although TGF-β blockade prevents aneurysms in MFS mouse models, the mechanisms through which excessive TGF-β causes aneurysms remain ill-defined.
We investigated the role of microRNA-29b (miR-29b) in aneurysm formation in MFS.
Using quantitative polymerase chain reaction, we discovered that miR-29b, a microRNA regulating apoptosis and extracellular matrix synthesis/deposition genes, is increased in the ascending aorta of Marfan (Fbn1(C1039G/+)) mice. Increased apoptosis, assessed by increased cleaved caspase-3 and caspase-9, enhanced caspase-3 activity, and decreased levels of the antiapoptotic proteins, Mcl-1 and Bcl-2, were found in the Fbn1(C1039G/+) aorta. Histological evidence of decreased and fragmented elastin was observed exclusively in the Fbn1(C1039G/+) ascending aorta in association with repressed elastin mRNA and increased matrix metalloproteinase-2 expression and activity, both targets of miR-29b. Evidence of decreased activation of nuclear factor κB, a repressor of miR-29b, and a factor suppressed by TGF-β, was also observed in Fbn1(C1039G/+) aorta. Furthermore, administration of a nuclear factor κB inhibitor increased miR-29b levels, whereas TGF-β blockade or losartan effectively decreased miR-29b levels in Fbn1(C1039G/+) mice. Finally, miR-29b blockade by locked nucleic acid antisense oligonucleotides prevented early aneurysm development, aortic wall apoptosis, and extracellular matrix deficiencies.
We identify increased miR-29b expression as key to the pathogenesis of early aneurysm development in MFS by regulating aortic wall apoptosis and extracellular matrix abnormalities.
Circulation Research 11/2011; 110(2):312-24. · 11.86 Impact Factor
[show abstract][hide abstract] ABSTRACT: Treatment of acute rejection (AR) in heart transplantation relies on histopathological grading of endomyocardial biopsies according to International Society for Heart and Lung Transplantation guidelines. Intragraft gene expression profiling may be a way to complement histological evaluation.
Transcriptional profiling was performed on 26 endomyocardial biopsies, and expression patterns were compared with the 1990 International Society for Heart and Lung Transplantation AR grades. Importantly, transcriptional profiles from settings with an equivalent AR grade appeared the same. In addition, grade 0 profiles could not be distinguished from 1A profiles, and grade 3A profiles could not be distinguished from 3B profiles. Comparing the AR groupings (0+1A, 1B, and 3A+3B), 0+1A showed more striking differences from 1B than from 3A+3B. When these findings were extrapolated to the 2005 revised guidelines, the combination of 1A and 1B into a single category (1R) appears to have brought together endomyocardial biopsies with different underlying processes that are not evident from histological evaluation. Grade 1B was associated with upregulated immune response genes, as 1 categorical distinction from grade 1A. Although grade 1B was distinct from the clinically relevant AR grades 3A and 3B, all of these grades shared a small number of overlapping pathways consistent with common physiological underpinnings.
The gene expression similarities and differences identified here in different AR settings have the potential to revise the clinical perspective on acute graft rejection, pending the results of larger studies.
[show abstract][hide abstract] ABSTRACT: Hemodynamically compromising rejection (HCR) is a major cause of mortality and morbidity after heart transplantation. Right ventricular (RV) function is a strong predictor of outcome in patients with heart failure and myocarditis. The objective of the current study is to determine whether RV dysfunction predicts event-free survival in patients with HCR.
Medical records of 548 heart transplant patients followed at Stanford University between January 1998 and January 2007 were reviewed. HCR was defined as a rejection episode requiring hospitalization for heart failure. Univariate and multivariate analyses were performed to identify risk factors for death or retransplantation at 1 year.
HCR occurred in 71 patients (12.9%). Death or retransplantation at 1 year occurred in 28 patients (39%). Univariate analysis identified non-cellular rejection (odds ratio [OR] = 3.20, p = 0.021), the need for inotropic support (OR = 4.80, p = 0.007), RV dysfunction (OR = 4.63, p = 0.006), left ventricular ejection fraction (OR = 0.941, p = 0.031) and acute renal failure (OR = 3.82, p = 0.010) as predictors of death or retransplantation at 1 year. Multivariate analysis identified RV dysfunction (OR = 4.80, p = 0.007) and the need for inotropic support (OR = 5.00, p = 0.009) as predictors of death or retransplantation at 1 year.
In the modern era of immunosuppression, HCR remains a major complication after heart transplantation. RV dysfunction was identified as a novel risk factor for death or retransplantation following HCR.
The Journal of heart and lung transplantation: the official publication of the International Society for Heart Transplantation 05/2009; 28(4):312-9. · 3.54 Impact Factor
[show abstract][hide abstract] ABSTRACT: In 1990, an international grading scheme for the grading of pulmonary allograft rejection was adopted by the International Society for Heart and Lung Transplantation (ISHLT) and was modified in 1995 by an expanded group of pathologists. The original and revised classifications have served the lung transplant community well, facilitating communication between transplant centers with regard to both patient management and research. In 2006, under the direction of the ISHLT, a multi-disciplinary review of the biopsy grading system was undertaken to update the scheme, address inconsistencies of use, and consider the current knowledge of antibody-mediated rejection in the lung. This article summarizes the revised consensus classification of lung allograft rejection. In brief, acute rejection is based on perivascular and interstitial mononuclear infiltrates, Grade A0 (none), Grade A1 (minimal), Grade A2 (mild), Grade A3 (moderate) and Grade A4 (severe), as previously. The revised (R) categories of small airways inflammation, lymphocytic bronchiolitis, are as follows: Grade B0 (none), Grade B1R (low grade, 1996, B1 and B2), Grade B2R (high grade, 1996, B3 and B4) and BX (ungradeable). Chronic rejection, obliterative bronchiolitis (Grade C), is described as present (C1) or absent (C0), without reference to presence of inflammatory activity. Chronic vascular rejection is unchanged as Grade D. Recommendations are made for the evaluation of antibody-mediated rejection, recognizing that this is a controversial entity in the lung, less well developed and understood than in other solid-organ grafts, and with no consensus reached on diagnostic features. Differential diagnoses of acute rejection, airway inflammation and chronic rejection are described and technical considerations revisited. This consensus revision of the working formulation was approved by the ISHLT board of directors in April 2007.
The Journal of heart and lung transplantation: the official publication of the International Society for Heart Transplantation 01/2008; 26(12):1229-42. · 3.54 Impact Factor
[show abstract][hide abstract] ABSTRACT: Bacterial myocarditis (BM) is an uncommon cause of infectious myocarditis. BM is usually seen in the context of overwhelming sepsis or as part of a specific bacterial syndrome. The definitive diagnosis of bacterial myocarditis requires biopsy or morphologically proven active myocarditis with evidence of bacterial invasion or positive tissue cultures. The management of bacterial myocarditis consists of aggressive and early antibiotic or anti-toxin treatment, appropriate hemodynamic support, and treatment of arrhythmias or mechanical complications. We present a case of acute Listeria monocytogenes myocarditis in an immunocompetent patient and highlight the challenges in the diagnosis and treatment of bacterial myocarditis.
The Journal of heart and lung transplantation: the official publication of the International Society for Heart Transplantation 08/2007; 26(7):745-9. · 3.54 Impact Factor
[show abstract][hide abstract] ABSTRACT: Both mast cells and IL-17 can contribute to host defense and pathology in part by orchestrating neutrophil recruitment, but the possible role of mast cells in IL-17-induced inflammation remains to be defined. We found that mast cells and IL-17, but neither IFN-gamma nor FcRgamma signaling, contributed significantly to the antigen (Ag)-dependent airway neutrophilia elicited in ovalbumin-specific T-cell receptor (TCR)-expressing C57BL/6-OTII mice, and that IFN-gamma significantly suppressed IL-17-dependent airway neutrophilia in this setting. IL-18, IL-1beta, and TNF each contributed significantly to the development of Ag- and T helper 17 (Th17 cell)-mediated airway neutrophilia. Moreover, IL-17 enhanced mast cell TNF production in vitro, and mast cell-associated TNF contributed significantly to Ag- and Th17 cell-mediated airway neutrophilia in vivo. By contrast, we detected no significant role for the candidate mediators histamine, PGD(2), LTB(4), CXCL10, or IL-16, each of which can be produced by mast cells and other cell types, in the neutrophil infiltration elicited in this model. These findings establish that mast cells and mast cell-derived TNF can significantly enhance, by FcRgamma-independent mechanisms, the Ag- and Th17 cell-dependent development of a neutrophil-rich inflammatory response at a site of Ag challenge.
[show abstract][hide abstract] ABSTRACT: Plasma procarboxypeptidase B (proCPB) is activated by the endothelial thrombin-thrombomodulin [corrected] complex. Activated proCPB [corrected] (CPB) functions as a fibrinolysis inhibitor, but it may play a broader role by inactivating inflammatory mediators. To test this hypothesis, C5a-induced alveolitis was studied in wild-type (WT) and proCPB-deficient mice (proCPB-/-). C5a-induced alveolitis, as measured by cell counts and total protein contents in bronchoalveolar lavage fluids, was markedly enhanced in the proCPB-/- mice. E229K thrombin, a thrombin mutant with minimal clotting activity but retaining its ability to activate protein C and proCPB, attenuated C5a-induced alveolitis in WT but not in proCPB-/- mice, indicating that its beneficial effect is mediated primarily by its activation of proCPB. Lung tissue histology confirmed these cellular inflammatory responses. Delayed administration of E229K thrombin after the C5a instillation was ineffective in reducing alveolitis in WT mice, suggesting that the beneficial effect of E229K thrombin is due to the direct inhibition of C5a by CPB. Our studies show that thrombin-activatable proCPB, in addition to its role in fibrinolysis, has intrinsic anti-inflammatory functions. Its activation, along with protein C, by the endothelial thrombin-TM complex represents a homeostatic response to counteract the inflammatory mediators generated at the site of vascular injury.
[show abstract][hide abstract] ABSTRACT: Correlative data suggest that mast cells adversely affect cardiac transplantation. This study uses a mast cell-deficient rat model to directly address the role of mast cells in cardiac allotransplantation. Standardized cardiac heterotopic transplantation with cyclosporine immunosuppression was performed in mast cell-deficient and mast cell-competent rats. Rejection, ischemia, fibrosis, fibrin deposition, numbers of T-cell receptor alpha/beta positive cells, expression of transforming growth factor-beta (TGF-beta), and of endothelin-1 (ET-1) and its receptors ETA and ETB were assessed. Differences in baseline cardiac gene expression were quantified by real-time PCR in a separate group of untransplanted animals. Baseline cardiac gene expression levels of all investigated growth factors, cytokines, ET-1, ETA, and ETB were similar in mast cell-deficient and mast cell-competent rats. Surprisingly, upon heterotopic transplantation, donor heart survival was significantly reduced in mast cell-deficient rats. Moreover, in mast cell-deficient donor hearts rejection was more severe, although nonsignificant, and extracellular matrix associated TGF-beta immunoreactivity was significantly lower than in mast cell-competent donor hearts. Fibrin immunoreactive area, on the other hand, was only increased in mast cell-deficient donor hearts, but not in mast cell-competent donor hearts. Histopathological changes in all donor hearts were accompanied by increased immunoreactivity for ET-1. In conclusion, this study shows that mast cells play a protective role after cardiac transplantation.
Transplant International 04/2007; 20(3):256-65. · 3.16 Impact Factor
[show abstract][hide abstract] ABSTRACT: Janus kinase 3 (JAK3) mediates signal transduction from cytokine receptors using the common gamma chain. The rationally designed inhibitor of JAK3, CP-690,550, prevents acute allograft rejection in rodents and in nonhuman primates. Here we investigated the ability of CP-690,550, to prevent allograft vasculopathy in a rodent model of aorta transplantation. Aortas from AxC Irish (RT1(a)) or Lewis (RT1(l)) rats were heterotopically transplanted into the infra-renal aorta of Lewis recipients and harvested at 28 or 56 days. Treated recipients received CP-690,550 by osmotic pumps (mean drug exposure of 110 +/- 38 ng/ml). Significant intimal hyperplasia was demonstrated in untreated allografts when compared with isografts at 28 days (2.08 +/- 0.85% vs. 0.43 +/- 0.2% luminal obliteration, respectively, P = 0.001) and 56 days (5.3 +/- 2.4% vs. 0.38 +/- 0.3%, P = 0.002). Treatment caused a 51% reduction in intimal hyperplasia at day 56. CP-690,550-treated animals also had a significant reduction of donor-specific IgG production and of the gene expression for suppressor of cytokine signaling-3 and with unchanged levels of expression of RANTES, IP-10 and transforming growth factor-beta1. These results are the first to show that JAK3 blockade by CP-690,550 effectively prevents allograft vasculopathy in this rat model of aorta transplantation.
Transplant International 01/2007; 19(12):1014-21. · 3.16 Impact Factor
[show abstract][hide abstract] ABSTRACT: Giant cell myocarditis (GCM) is an uncommon disorder that affects ventricular myocardium causing severe left ventricular dysfunction and ventricular arrhythmias. We report a case of GCM that only affected the atrium sparing the ventricle.
Pacing and Clinical Electrophysiology 11/2006; 29(10):1179-80. · 1.75 Impact Factor
[show abstract][hide abstract] ABSTRACT: We evaluated an endobronchial valve device in the treatment of surgically created air leak or pneumothorax by eliminating antegrade flow.
Six sheep underwent general anesthesia with positive pressure ventilation and left thoracotomy. After division of the mediastinal pleura, the contralateral cranial lobe was identified and a 2.5 cmx1.5 cm laceration created with resultant air leak. Using bronchoscopy, we deployed a valve device in the bronchus of the injured segment. Chest drainage tube was placed and the thoracotomy closed. At 1 week (n=3) and 4 weeks (n=3), the animals underwent general anesthesia, bronchoscopy and right thoracotomy.
All animals survived the procedure. Bronchoscopic valve device placement in the segmental bronchus resolved the air leak immediately. After closure of thoracotomy, the chest tube demonstrated minimal drainage with no air leak. At 1 and 4 weeks, bronchoscopy showed no change in device location, and the treated segments were atelectatic with fibrous scar at the injured site.
Collapse of a selected lung segment with resolution of air leak can be achieved using bronchoscopically implanted valve device. The valve device may facilitate treatment of patients with post-surgical or post-traumatic persistent air leak.
Respiratory Medicine 09/2006; 100(8):1402-6. · 2.59 Impact Factor