Cardiac allograft vasculopathy: central role of endothelial injury leading to transplant "atheroma"

Leukotriene B4: A potential mediator and biomarker for cardiac allograft vasculopathy

BACKGROUND

Cardiac allograft vasculopathy (CAV) remains the leading cause of long-term graft failure and mortality after heart transplantation. Effective preventive and treatment options are not available to date, largely because underlying mechanisms remain poorly understood. We studied the potential role of leukotriene B4 (LTB4), an inflammatory lipid mediator, in the development of CAV.

METHODS

We used an established preclinical rat CAV model to study the role of LTB4 in CAV. We performed syngeneic and allogeneic orthotopic aortic transplantation, after which neointimal proliferation was quantified. Animals were then treated with Bestatin, an inhibitor of LTB4 synthesis, or vehicle control for 30 days post-transplant, and evidence of graft CAV was determined by histology. We also measured serial LTB4 levels in a cohort of 28 human heart transplant recipients with CAV, 17 matched transplant controls without CAV, and 20 healthy nontransplant controls.

RESULTS

We showed that infiltration of the arterial wall with macrophages leads to neointimal thickening and a rise in serum LTB4 levels in our rat model of CAV. Inhibition of LTB4 production with the drug Bestatin prevents development of neointimal hyperplasia, suggesting that Bestatin may be effective therapy for CAV prevention. In a parallel study of heart transplant recipients, we found nonsignificantly elevated plasma LTB4 levels in patients with CAV, compared to patients without CAV and healthy, nontransplant controls.

CONCLUSIONS

This study provides key evidence supporting the role of the inflammatory cytokine LTB4 as an important mediator of CAV development and provides preliminary data suggesting the clinical benefit of Bestatin for CAV prevention.

Cardiac allograft vasculopathy in heart transplant recipients from hepatitis C viremic donors

BACKGROUND

Recent studies suggest the transplantation of Hepatitis C (HCV) hearts from viremic donors is associated with comparable 1 year survival to nonviremic donors. Though HCV viremia is a known risk factor for accelerated atherosclerosis, data on cardiac allograft vasculopathy (CAV) outcomes are limited. We compared the incidence of CAV in heart transplant recipients from HCV viremic donors (nucleic acid amplification test positive; NAT+) compared to non-HCV infected donors (NAT-).

METHODS

We retrospectively reviewed annual coronary angiograms with intravascular ultrasound from April 2017 to August 2020 at two large cardiac transplant centers. CAV was graded according to ISHLT guidelines. Maximal intimal thickness (MIT) ≥ 0.5 mm was considered significant for subclinical disease.

RESULTS

Among 270 heart transplant recipients (mean age 54; 77% male), 62 patients were transplanted from NAT+ donors. CAV ≥ grade 1 was present in 8.8% of the NAT+ versus 16.8% of the NAT- group at 1 year, 20% versus 28.8% at 2 years, and 33.3% versus 41.5% at 3 years. After adjusting for donor age, donor smoking history, recipient BMI, recipient, hypertension, and recipient diabetes, NAT+ status did not confer increased risk of CAV (HR.80; 95% CI.45-1.40, p = 0.43) or subclinical IVUS disease (HR.87; 95% CI.58-1.30, p = 0.49). Additionally, there was no difference in the presence of rapidly progressive lesions on IVUS.

CONCLUSION

Our data show that NAT+ donors conferred no increased risk for early CAV or subclinical IVUS disease following transplantation in a cohort of heart transplant patients who were treated for HCV, suggesting the short-term safety of this strategy to maximize the pool of available donor hearts.

Role of ascorbic acid in cardiac allograft vasculopathy

PURPOSE OF THE REVIEW

Cardiac allograft vasculopathy (CAV) is a progressive fibroproliferative disease which occurs after heart transplantation and is associated with significant long-term morbidity and mortality. Currently available strategies including statins, mammalian target of rapamycin (mTOR) inhibitors, and revascularization, have limited overall effectiveness in treating this pathology once the disease process is established. mTOR inhibitors, while effective when used early in the disease process, are not well tolerated, and hence not routinely used in post-transplant care.

RECENT DATA

Recent work on rodent models have given us a novel mechanistic understanding of effects of ascorbic acid in preventing CAV. TET methyl cytosine dioxygenase2 (TET2) reduces vascular smooth muscle cell (VSMC) apoptosis and intimal thickening. TET2 is repressed by interferon γ (IFNγ) in the setting of CAV. Ascorbic acid has been shown to promote TET2 activity and attenuate allograft vasculopathy in animal models and CAV progression in a small clinical trial.

SUMMARY

CAV remains a challenging disease process and needs better preventative strategies. Ascorbic acid improves endothelial dysfunction, reduces reactive oxygen species, and prevents development of intimal hyperplasia by preventing smooth muscle cell apoptosis and hyperproliferation. Further large-scale randomized control studies of ascorbic acid are needed to establish the role in routine post-transplant management.

Early optical coherence tomography evaluation of donor-transmitted atherosclerosis and cardiac allograft vasculopathy: insights from a prospective, single-center study

BACKGROUND

The impact of donor transmitted atherosclerosis as assessed by intravascular ultrasound on development and progression of cardiac allograft vasculopathy (CAV) after heart transplantation (HT) remains poorly defined in contemporary practice. In this exploratory analysis, we sought to assess the prognostic role of early qualitative assessment of donor artery morphology using optical coherence tomography (OCT) as a more sensitive imaging modality.

METHODS

HT recipients were prospectively enrolled for baseline OCT imaging of the left anterior descending coronary artery. OCT findings were classified as normal, homogeneous intimal thickening, and advanced plaque characteristics. The endpoint was a composite of cardiac death, myocardial infarction, or new angiographically detectable CAV stratified by the International Society of Heart and Lung Transplantation criteria up to 4 years of follow-up.

RESULTS

A total of 35 patients underwent baseline OCT of whom 51.4% had normal OCT, 14.3% had homogenous plaque, and 34.3% had advanced characteristics. There were no significant differences in baseline demographics between patients with and without normal morphology. During a mean follow-up of 3.3 ± 0.4 years, the endpoint occurred in 11 patients including 1 death, 7 CAV1, 3 CAV2, and 1 CAV3. Kaplan-Meier analysis revealed a significantly higher event rate in patients with advanced characteristics (log-rank p = 0.010). In multivariate analysis, OCT-based plaque morphology was an independent predictor of clinical events (adjusted hazard ratio 4.57, 95% confidence interval 1.50-13.92, p = 0.008) while maximal intimal thickness ≥0.5 mm was not.

CONCLUSIONS

Early qualitative OCT assessment of donor coronary artery morphology appears to be a reliable marker for predicting future cardiovascular events in HT recipients. Our findings warrant more careful study in a larger cohort.

Immunoengineered MXene nanosystem for mitigation of alloantigen presentation and prevention of transplant vasculopathy

MXenes are an emerging class of nanomaterials with significant potential for applications in nanomedicine. Amongst MXene technologies, titanium carbide (Ti₃C₂T_x) nanomaterials are the most mature and have received significant attention to tackle longstanding clinical challenges due to its tailored physical and material properties. Cardiac allograft vasculopathy is an aggressive form of atherosclerosis and a major cause of mortality among patients with heart transplants. Blood vessel endothelial cells (ECs) stimulate alloreactive T-lymphocytes to result in sustained inflammation. Herein, we report the first application of Ti₃C₂T_x MXene nanosheets for prevention of allograft vasculopathy. MXene nanosheets interacted with human ECs and downregulated the expression of genes involved in alloantigen presentation, and consequently reduced the activation of allogeneic lymphocytes. RNA-Seq analysis of lymphocytes showed that treatment with MXene downregulated genes responsible for transplant-induced T-cell activation, cell-mediated rejection, and development of allograft vasculopathy. In an in vivo rat model of allograft vasculopathy, treatment with MXene reduced lymphocyte infiltration and preserved medial smooth muscle cell integrity within transplanted aortic allografts. These findings highlight the potential of Ti₃C₂T_x MXene in treatment of allograft vasculopathy and inflammatory diseases.

Cytokine Adsorber Use during DCD Heart Perfusion Counteracts Coronary Microvascular Dysfunction

Microvascular dysfunction (MVD) in cardiac allografts is associated with an impaired endothelial function in the coronary microvasculature. Ischemia/reperfusion injury (IRI) deteriorates endothelial function. Hearts donated after circulatory death (DCD) are exposed to warm ischemia before initiating ex vivo blood perfusion (BP). The impact of cytokine adsorption during BP to prevent MVD in DCD hearts is unknown. In a porcine DCD model, we assessed the microvascular function of hearts after BP with (DCD-BPCytoS, n = 5) or without (DCD-BP, n = 5) cytokine adsorption (CytoSorb®). Microvascular autoregulation was assessed by increasing the coronary perfusion pressure, while myocardial microcirculation was measured by Laser-Doppler-Perfusion (LDP). We analyzed the immunoreactivity of arteriolar oxidative stress markers nitrotyrosine and 4-hydroxy-2-nonenal (HNE), endothelial injury indicating cell adhesion molecules CD54, CD106 and CD31, and eNOS. We profiled the concentration of 13 cytokines in the perfusate. The expression of 84 genes was determined and analyzed using machine learning and decision trees. Non-DCD hearts served as a control for the gene expression analysis. Compared to DCD-BP, relative LDP was improved in the DCD-BPCytoS group (1.51 ± 0.17 vs. 1.08 ± 0.17). Several pro- and anti-inflammatory cytokines were reduced in the DCD-BPCytoS group. The expression of eNOS significantly increased, and the expression of nitrotyrosine, HNE, CD54, CD106, and CD31, markers of endothelial injury, majorly decreased in the DCD-BPCytoS group. Three genes allowed exact differentiation between groups; regulation of HIF1A enabled differentiation between perfusion (DCD-BP, DCD-BPCytoS) and non-perfusion groups. CAV1 allowed differentiation between BP and BPCytoS. The use of a cytokine adsorption device during BP counteracts preload-dependent MVD and preserves the microvascular endothelium by preventing oxidative stress and IRI of coronary arterioles of DCD hearts.

Ghrelin May Inhibit Inflammatory Response and Apoptosis During Ischemia-Reperfusion Injury

BACKGROUND

Ghrelin, a novel growth hormone-releasing peptide, has both anti-inflammatory and anti-apoptotic effects on human endothelial cells. We evaluated the protective effects of ghrelin against ischemia-reperfusion injury (IRI) in a murine heterotopic cervical heart transplantation model.

METHODS

Donor hearts from C57BL/6J wild-type mice, which were kept in cold saline for 60 minutes, were heterotopically transplanted into C57BL/6J wild-type recipients. A day prior to heterotopic cervical heart transplantation, donor animals received either ghrelin (300 nmol/kg) or saline (0.3 mL) intraperitoneally. Upon reperfusion and postoperative day 1, ghrelin or saline was administered to the recipients. Donor hearts were procured on day 2.

RESULTS

Ghrelin injection did not result in any adverse effects in donors or recipients. Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling-positive cells were significantly decreased in the ghrelin group (0.38% ± 0.21% vs 5.74% ± 3.68%; P < .001). Both cleaved caspase-3 activity and Bcl-2/Bax ratio from the ghrelin group were significantly reduced compared to those in the control. Furthermore, the phosphorylated Akt/Akt ratio was higher in the ghrelin group (0.44 ± 0.21 vs 0.14 ± 0.03; P = .043). Nuclear factor-kappa B p65 nuclear translocation was reduced in the ghrelin hearts compared to the controls (3.17% ± 1.84% vs 19.28% ± 13.14%; P = .009). Vascular cell adhesion molecule-1, intracellular adhesion molecule-1, nuclear factor-kappa B, and tumor necrosis factor alpha levels were also significantly reduced in the ghrelin-treated group. No significant difference was observed in 8-isoprostane production between groups.

CONCLUSION

Ghrelin inhibits the inflammatory response and apoptosis during transplant-related IRI. This study demonstrates the protective effects of ghrelin against IRI.

Analysis of Fibrotic Plaques in Angiographic Manifest Cardiac Allograft Vasculopathy in Long-term Heart Transplanted Patients Using Optical Coherence Tomography

Supplemental Digital Content is available in the text.

Background.

The development and progression of cardiac allograft vasculopathy documented by coronary angiography (CAV_angio) after heart transplantation (HTx) has prognostic relevance. Yet there are limited data regarding the role of concomitant intracoronary imaging in the presence CAV_angio. In particular, atherosclerotic plaques might represent a potential target for prevention, but their impact on stenosis is understudied.

Methods.

We used high-resolution intracoronary optical coherence tomography (OCT) to quantify and compare findings of intimal hyperplasia (IH) and plaque morphologies in HTx patients (fibrotic plaque, lipid plaque, and calcified plaque). OCT findings were related to the presence of CAV_angio as well as to the severity of stenosis.

Results.

We included 65 consecutive patients into analysis (66% with CAV_angio, posttransplant interval 9.9 ± 7.6 y). Fibrotic, lipid, and calcified plaques were present in 41 (63.1%), 39 (60%), and 18 (27.7%) patients, respectively. In addition to IH, the presence of fibrotic, lipid, and calcified plaques was found to be associated with CAV_angio. The prevalence of lipid plaque and quantitative measurements of fibrotic plaque increased with stenosis severity (lipid plaque, P < 0.001, maximal and mean fibrotic arc, P = 0.05 and P = 0.001, respectively). Receiver operating characteristic analysis showed that area under the curve of the fibrotic plaque parameter mean fibrotic arc (0.87, 95% confidence interval [0.76-0.99]; P = 0.002) was superior to area under the curve of intima parameters regarding CAV_angio. The effect of mean fibrotic arc (r = 0.52, P < 0.001) was relevant regarding stenosis severity.

Conclusions.

After a longer posttransplant interval, CAV findings in OCT included a combination of IH and atherosclerotic plaques. In addition to IH, the presence of fibrotic, lipid, and calcified plaques is associated with CAV_angio. Further studies are warranted to evaluate if the in vivo screening for plaque progress, particularly of fibrotic plaque, could improve individual secondary prevention and outcome in HTx patients.

Early aspirin use, allograft rejection, and cardiac allograft vasculopathy in heart transplantation

BACKGROUND

Early aspirin (ASA) use after orthotopic heart transplantation (OHT) has been associated with lower rates of cardiac allograft vasculopathy (CAV). We hypothesized that the inverse association between ASA use and CAV incidence may be most pronounced in patients with allograft rejection.

METHODS

Patients receiving OHT at a single center 2004-2010 (n = 120) were categorized by early ASA use post-transplant (ASA use for > 6 months in the first year) and the presence of biopsy-defined acute cellular rejection (ACR) and/or antibody-mediated rejection (AMR) during 5-year follow-up. Propensity scores for ASA treatment were estimated using boosting models and applied by inverse probability of treatment weighting. The association between ASA use and time to moderate/severe CAV (ISHLT ≥ 2) was investigated.

RESULTS

Among patients with ACR or AMR, ASA therapy was associated with significantly lower rates of CAV≥ 2 (3.3 vs. 30.1%; P = .001; HR_adj .07; 95% CI .01-.52), whereas ASA therapy was not associated with lower rates of CAV in patients with no rejection (5.6 vs. 5.3%; P = .90; HR_adj 1.26; 95% CI .08-20.30; p_interaction  = .09).

CONCLUSIONS

Early ASA use after OHT was associated with lower rates of moderate to severe CAV only in those patients with episodes of allograft rejection.

M2 Macrophages Serve as Critical Executor of Innate Immunity in Chronic Allograft Rejection

Allograft functional failure due to acute or chronic rejection has long been a major concern in the area of solid organ transplantation for decades. As critical component of innate immune system, the macrophages are unlikely to be exclusive for driving acute or chronic sterile inflammation against allografts. Traditionally, macrophages are classified into two types, M1 and M2 like macrophages, based on their functions. M1 macrophages are involved in acute rejection for triggering sterile inflammation thus lead to tissue damage and poor allograft survival, while M2 macrophages represent contradictory features, playing pivotal roles in both anti-inflammation and development of graft fibrosis and resulting in chronic rejection. Macrophages also contribute to allograft vasculopathy, but the phenotypes remain to be identified. Moreover, increasing evidences are challenging traditional identification and classification of macrophage in various diseases. Better understanding the role of macrophage in chronic rejection is fundamental to developing innovative strategies for preventing late graft loss. In this review, we will update the recent progress in our understanding of diversity of macrophage-dominated innate immune response, and reveal the roles of M2 macrophages in chronic allograft rejection as well.

The effect of antiplatelet therapy on survival and cardiac allograft vasculopathy following heart transplantation: A systematic review and meta-analysis

Cardiac allograft vasculopathy (CAV) is mediated by endothelial inflammation, platelet activation and thrombosis. Antiplatelet therapy may prevent the development of CAV. This systematic review and meta-analysis summarizes and appraises the evidence on the effect of antiplatelet therapy after heart transplantation (HT). CENTRAL(Ovid), MEDLINE(Ovid), Embase(Ovid) were searched from inception until April 30, 2020. Outcomes included CAV, all-cause mortality, and CAV-related mortality. Data were pooled using random-effects models. Seven observational studies including 2023 patients, mean age 52 years, 22% female, 47% with ischemic cardiomyopathy followed over a mean 7.1 years proved eligible. All studies compared acetylsalicylic acid (ASA) to no treatment and were at serious risk of bias. Data from 1911 patients in 6 studies were pooled in the meta-analyses. The evidence is very uncertain about the effect of ASA on all-cause or CAV-related mortality. ASA may reduce the development of CAV (RR 0.75, 95% CI: 0.44-1.29) based on very low certainty evidence. Two studies that conducted propensity-weighted analyses showed further reduction in CAV with ASA (HR 0.31, 95% CI: 0.13-0.74). In conclusion, there is limited evidence that ASA may reduce the development of CAV. Definitive resolution of the impact of antiplatelet therapy on CAV and mortality will require randomized clinical trials.

Twenty-four-hour normothermic perfusion of isolated ex vivo hearts using plasma exchange

OBJECTIVE

Cross-circulation of plasma from a paracorporeal animal allows successful ex vivo heart perfusion (EVHP) for 3 days. Little is known about the feasibility of prolonged EVHP without a paracorporeal animal. These experiments evaluated plasma exchange (PX) that infuses fresh plasma, whereas an equal amount is removed to replace paracorporeal cross-circulation.

METHODS

Ten hearts were procured from 8 to 10 kg piglets and maintained with EVHP. The EVHP circuit was primed with platelet- and leukocyte-reduced blood. Plasma obtained from stored porcine blood (4°C for ≤7 days) was infused and removed with a plasma separator at 1 mL/h/g cardiac tissue (n = 5) in the PX group. Controls (n = 5) used the same EVHP without PX. Antegrade aortic perfusion was adjusted to reach physiologic coronary flow of 0.7 to 1.2 mL/min/g, normothermia (37°C), and hemoglobin ≥8 g/dL. Viability was assessed by hemodynamic metrics, metabolic assays, and histopathology.

RESULTS

All PX hearts remained viable for 24 hours compared with only 1 control (P = .015). Coronary resistance was higher in the PX versus controls (1.06 ± 0.06 mm Hg/mL/min; 0.58 ± 0.02 mm Hg/mL/min [P < .05]). Lactate levels were lower in PX (2.8-4.2 mmol/L) versus controls (3.6-7.6 mmol/L) (P < .05). PX demonstrated a trend toward preservation of left ventricle systolic pressure (63.0 ± 10.9 mm Hg) versus controls (37 ± 22.0 mm Hg) (P > .05). In mixed effect models, oxygen consumption was higher with PX (P < .05). Histopathologic evaluation confirmed extensive myocardial degeneration and worse interstitial edema in controls.

CONCLUSIONS

These results demonstrate that EVHP can be successfully maintained for at least 24 hours using continuous PX. This eliminates the need for a paracorporeal animal and provides an important step toward clinical application.

Kv1.3 blockade inhibits proliferation of vascular smooth muscle cells in vitro and intimal hyperplasia in vivo

The modulation of voltage-gated K⁺ (Kv) channels, involved in cell proliferation, arises as a potential therapeutic approach for the prevention of intimal hyperplasia present in in-stent restenosis (ISR) and allograft vasculopathy (AV). We studied the effect of PAP-1, a selective blocker of Kv1.3 channels, on development of intimal hyperplasia in vitro and in vivo in 2 porcine models of vascular injury. In vitro phenotypic modulation of VSMCs was associated to an increased functional expression of Kv1.3 channels, and only selective Kv1.3 channel blockers were able to inhibit porcine VSMC proliferation. The therapeutic potential of PAP-1 was then evaluated in vivo in swine models of ISR and AV. At 15-days follow-up, morphometric analysis demonstrated a substantial reduction of luminal stenosis in the allografts treated with PAP-1 (autograft 2.72 ± 1.79 vs allograft 10.32 ± 1.92 vs allograft + polymer 13.54 ± 8.59 vs allograft + polymer + PAP-1 3.06 ± 1.08 % of luminal stenosis; P = 0.006) in the swine model of femoral artery transplant. In the pig model of coronary ISR, using a prototype of PAP-1-eluting stent, no differences were observed regarding % of stenosis compared to control stents (31 ± 13 % vs 37 ± 18%, respectively; P = 0.372) at 28-days follow-up. PAP-1 treatment was safe and did not impair vascular healing in terms of delayed endothelialization, inflammation or thrombosis. However, an incomplete release of PAP-1 from stents was documented. We conclude that the use of selective Kv1.3 blockers represents a promising therapeutic approach for the prevention of intimal hyperplasia in AV, although further studies to improve their delivery method are needed to elucidate its potential in ISR.

Everolimus Initiation With Early Calcineurin Inhibitor Withdrawal in De Novo Heart Transplant Recipients: Long-term Follow-up From the Randomized SCHEDULE Study

BACKGROUND

A calcineurin inhibitor (CNI)-free immunosuppressive regimen has been demonstrated to improve renal function early after heart transplantation, but long-term outcome of such a strategy has not been well described.

METHODS

In the randomized SCHEDULE trial, de novo heart transplant recipients received (1) everolimus with reduced-exposure CNI (cyclosporine) followed by CNI withdrawal at week 7-11 posttransplant or (2) standard-exposure cyclosporine, both with mycophenolate mofetil and corticosteroids; 95/115 randomized patients were followed up at 5-7 years posttransplant.

RESULTS

Mean measured glomerular filtration rate was 74.7 mL/min and 62.4 mL/min with everolimus and CNI, respectively. The mean difference was in favor of everolimus by 11.8 mL/min in the intent-to-treat population (P = 0.004) and 17.2 mL/min in the per protocol population (n = 75; P < 0.001). From transplantation to last follow-up, the incidence of biopsy-proven acute rejection (BPAR) was 77% (37/48) and 66% (31/47) (P = 0.23) with treated BPAR in 50% and 23% (P < 0.01) in the everolimus and CNI groups, respectively; no episode led to hemodynamic compromise. Coronary allograft vasculopathy (CAV) assessed by coronary intravascular ultrasound was present in 53% (19/36) and 74% (26/35) of everolimus- and CNI-treated patients, respectively (P = 0.037). Graft dimensions and function were similar between the groups. Late adverse events were comparable.

CONCLUSIONS

These results suggest that de novo heart transplant patients randomized to everolimus and low-dose CNI followed by CNI-free therapy maintain significantly better long-term renal function as well as significantly reduced CAV than patients randomized to standard CNI treatment. Increased BPAR in the everolimus group during year 1 did not impair long-term graft function.

The role of optical coherence tomography and other intravascular imaging modalities in cardiac allograft vasculopathy

Orthotopic heart transplantation (OHT) is the standard-of-care for end-stage heart disease. Although a significant improvement in the prognosis of patients after OHT has been observed in recent years, their overall mortality remains relatively high, with a median survival of approximately 10 years after transplantation. One of the primary causes of death in patients after OHT is cardiac allograft vasculopathy (CAV), the condition developing specifically in the coronary vasculature after OHT, the pathophysiology of which is still inadequately known. It is estimated that CAV development and progression is responsible for approximately 30% of deaths within five years post-OHT. According to the International Society for Heart and Lung Transplantation (ISHLT) Nomenclature for CAV, its presence should be assessed primarily by the coronary angiography performed routinely after OHT, mostly due to its wide availability, reproducibility, and low complication rate. However, the analysis of CAV in coronary angiography has limitations, mostly concerning its - sometimes inadequate - sensitivity and specificity. Hence, there is a growing need for the introduction of more accurate methods of CAV assessment, such as intravascular imaging, which through a thorough evaluation of the arterial wall structure and thickness allows the drawbacks of routine angiography to be minimised. The aim of the article was to critically summarise the current findings derived from the analysis of CAV by optical coherence tomography, the other intravascular imaging modalities, such as intravascular ultrasound (IVUS) and IVUS-derived virtual histology, along with physiological assessment with the use of the fractional flow reserve.

Protective role of Nrf2 against ischemia reperfusion injury and cardiac allograft vasculopathy

Ischemia-reperfusion injury (IRI) and cardiac allograft vasculopathy (CAV) remain unsolved complications post-heart transplant (Tx). The antioxidant transcription factor Nuclear factor erythroid 2-related factor 2 (Nrf2) has been suggested to inhibit reactive oxygen species-mediated NF-κB activation. We hypothesized that Nrf2 inhibits NF-κB activation post-Tx and suppresses IRI and the subsequent development of CAV. IRI and CAV were investigated in murine heterotopic Tx models, respectively. Nrf2 wild-type (WT) and KO mice were used as donors. Sulforaphane was used as an Nrf2 agonist. In saline-treated animals following 24 hours of reperfusion in isogenic grafts, Nrf2-KO showed significantly less SOD1/2 activity compared with WT. Nrf2-KO displayed significantly high total and phosphorylated p65 expressions and percentage of cells with nuclear p65. mRNA levels of NF-κB-mediated proinflammatory genes were also high. Graft dysfunction, apoptosis, and caspase-3 activity were significantly higher in Nrf2-KO. In the allograft studies, graft beating score was significantly weaker in Nrf2-KO compared with WT. Nrf2-KO also demonstrated significantly more coronary luminal narrowing. In WT animals, sulforaphane successfully augmented all the protective effects of Nrf2 with increase of SOD2 activity. Nrf2 inhibits NF-κB activation and protects against IRI via its antioxidant properties and suppresses the subsequent development of CAV.

AAV-Mediated Expression of AP-1-Neutralizing RNA Decoy Oligonucleotides Attenuates Transplant Vasculopathy in Mouse Aortic Allografts

Transplant vasculopathy (TV), characterized by obstructive lesions in affected vessels, represents one of the long-term complications of cardiac transplantation. Activation of the transcription factor activator protein-1 (AP-1) is implicated in smooth muscle cell (SMC) phenotypic switch from contractile to synthetic function, increasing the migration and proliferation rate of these cells. We hypothesize that adeno-associated virus (AAV)-mediated delivery of an RNA hairpin AP-1 decoy oligonucleotide (dON) might effectively ameliorate TV severity in a mouse aortic allograft model. Aortic allografts from DBA/2 mice ex vivo transduced with modified AAV9-SLR carrying a targeting peptide within the capsid surface were transplanted into the infrarenal aorta of C57BL/6 mice. Cyclosporine A (10 mg/kg BW) was administered daily. AP-1 dONs were intracellularly expressed in the graft tissue as small hairpin RNA proved by fluorescent in situ hybridization. Explantation after 30 days and histomorphometric evaluation revealed that AP-1 dON treatment significantly reduced intima-to-media ratio by 41.5% (p < 0.05) in the grafts. In addition, expression of adhesion molecules, cytokines, as well as numbers of proliferative SMCs, matrix metalloproteinase-9-positive cells, and inflammatory cell infiltration were significantly decreased in treated aortic grafts. Our findings demonstrate the feasibility, efficacy, and specificity of the anti-AP-1 RNA dON approach for the treatment of allograft vasculopathy in an animal model. Moreover, the AAV-based approach in general provides the possibility to achieve a prolonged delivery of nucleic-acids-based therapeutics in to the blood vessel wall.

Metformin therapy in patients with diabetes mellitus is associated with a reduced risk of vasculopathy and cardiovascular mortality after heart transplantation

Background

Cardiac allograft vasculopathy (CAV) is a major cause of morbidity and mortality following heart transplantation (HT). Reduced cardiovascular mortality and morbidity have been reported in non-HT patients treated with metformin. Given the high prevalence of type 2 diabetes mellitus (T2DM) in HT patients, we investigated the association between metformin therapy and cardiovascular outcomes after HT.

Methods

The study population comprised 103 DM patients who had undergone HT between 1994 and 2018 and were prospectively followed-up. We excluded from the study patients with type 1 diabetes mellitus. Fifty-five HT patients (53%) in the cohort were treated with metformin. Clinical data were recorded on prospectively designed forms. The primary outcomes included CAV, survival, and the combined end-point of CAV or cardiovascular mortality.

Results

Kaplan–Meier survival analysis showed that the CAV rate at 20 years of follow-up was lower in DM patients treated with metformin than in those who were not (30 vs. 65%; log-rank p = 0.044). Similarly, the combined risk of CAV or cardiovascular mortality was lower in the metformin-treated patients than in those not receiving metformin (32 vs. 68%; log rank p = 0.01). Consistently, multivariate analysis adjusted for age and comorbidities showed that metformin therapy was independently associated with a significant 90% reduction (95% confidence interval 0.02–0.46, p = 0.003) in the risk for the development of CAV, and a 91% reduction (95% confidence interval 0.02–0.42; p = 0.003) in the risk for CAV or cardiovascular mortality.

Conclusions

In diabetic HT patients, metformin therapy is independently associated with a significant reduction in the long-term risk for CAV and the combined end-point of CAV or cardiovascular mortality after HT.

Comprehensive morphologic and functional imaging of heart transplant patients: first experience with dynamic perfusion CT

OBJECTIVES

We aimed to assess the diagnostic performance of a combined protocol with coronary computed tomography angiography (CCTA) and stress CT perfusion imaging (CTP) in heart transplant patients for comprehensive morphological and functional imaging.

METHODS

In this prospective study, 13 patients undergoing routine follow-up 8±6 years after heart transplantation underwent CCTA and dynamic adenosine stress CTP using a third-generation dual-source CT scanner, cardiac magnetic resonance (MR) adenosine stress perfusion imaging at 1.5 T, and catheter coronary angiography. In CCTA stenoses >50% luminal diameter narrowing were noted. Myocardial perfusion deficits were documented in CTP and MR. Quantitative myocardial blood flow (MBF) was calculated with CTP. Left ventricular ejection fraction was determined on cardiac MR cine images. Radiation doses of CT were determined.

RESULTS

One of the 13 patients had to be excluded because of severe motion artifacts. CCTA identified three patients with stenosis >50%, which were confirmed with catheter coronary angiography. CTP showed four patients with stress-induced myocardial hypoperfusion, which were confirmed by MR stress perfusion imaging. Quantitative analysis of global MBF showed lower mean values as compared to known reference values (MBF under stress 125.5 ± 34.5 ml/100 ml/min). Average left ventricular ejection fraction was preserved (56 ± 5%).

CONCLUSIONS

In heart transplant patients, a comprehensive CT protocol for the assessment of morphology and function including CCTA and CTP showed good concordance to results from MR perfusion imaging and catheter coronary angiography.

KEY POINTS

• Stress CT perfusion imaging enables the detection of myocardial ischemia • CT myocardial perfusion imaging can be combined with coronary computed tomography angiography • Combining perfusion and coronary CT imaging is accurate in heart transplant patients • CT myocardial perfusion imaging can be performed at a reasonable radiation dose.

HHEX: A Crosstalker between HCMV Infection and Proliferation of VSMCs

Objective: The study was designed to evaluate the role of Human cytomegalovirus (HCMV) infection on homebox (HOX) gene expression and the effects of overexpression of HOX genes on proliferation and apoptosis of vascular smooth muscle cells (VSMCs).

Methods: Viral infection was verified by observation of cytopathic effects through inverted microscopy, viral particles by electron microscopy and HCMV IE gene amplification by RT-PCR. cDNA profiling technology was used to screen expression of HOX genes after HCMV infection in VSMCs. Abnormal expression of Haematopoietically-expressed homeobox (HHEX) was selected to construct over-expressed vector and transfected into VSMCs. The effects of over expression of HHEX on cell proliferation and apoptosis of VSMCs were assayed by flow cytometry. Apoptosis and proliferation-associated genes were also assayed by RT-PCR.

Results: Multiple HOX gene expression levels had obvious changes after HCMV infection, among which expression of HHEX gene increased obviously at 24, 48, and 72 h after infection. Over expression of HHEX can promote VSMCs proliferation by promoting G0/G1 phase cells into S phase and inhibit VSMCs apoptosis. HHEX inhibited the expression of apoptosis-associated caspase 2 and caspase3 and promoted the expression of cell cycle-related genes such as CDK2 and CDK6, CyclinB2 and CyclinD2.

Conclusion: HHEX over expression induced by HCMV infection closely associated with vascular proliferative diseases.

ADMA: its role in vascular disease

Endothelium-derived nitric oxide (NO) is the most potent endogenous vasodilator and, by virtue of its anti-inflammatory and anti-thrombotic effects, it is an endogenous anti-atherogenic agent. Accordingly, impairment of NO synthesis or bioactivity may increase the risk of vascular disease. Asymmetric dimethylarginine (ADMA) is an endogenous inhibitor of the NO synthase pathway. Plasma levels of ADMA are increased in patients with vascular disease, or with risk factors for vascu lar disease. Preclinical and clinical studies indicate that ADMA may mediate the adverse effects of traditional risk factors on endothelial vasodilator function. By impairing endothelial function, ADMA may contribute to pulmonary or systemic hypertension, as well as to vascular disease. Several drugs known to treat cardiovas cular disease also reduce plasma ADMA levels, such as angiotensin receptor antag onists, converting enzyme inhibitors, and insulin sensitizing agents. Plasma ADMA may be a common mediator of endothelial dysfunction induced by vascular risk factors. Insights into the mechanisms by which plasma ADMA is regulated may lead to new therapeutic knowledge.

ADMA: its role in vascular disease

Endothelium-derived nitric oxide (NO) is the most potent endogenous vasodilator and, by virtue of its anti-inflammatory and anti-thrombotic effects, it is an endogenous anti-atherogenic agent. Accordingly, impairment of NO synthesis or bioactivity may increase the risk of vascular disease. Asymmetric dimethylarginine (ADMA) is an endogenous inhibitor of the NO synthase pathway. Plasma levels of ADMA are increased in patients with vascular disease, or with risk factors for vascular disease. Preclinical and clinical studies indicate that ADMA may mediate the adverse effects of traditional risk factors on endothelial vasodilator function. By impairing endothelial function, ADMA may contribute to pulmonary or systemic hypertension, as well as to vascular disease. Several drugs known to treat cardiovascular disease also reduce plasma ADMA levels, such as angiotensin receptor antagonists, converting enzyme inhibitors, and insulin sensitizing agents. Plasma ADMA may be a common mediator of endothelial dysfunction induced by vascular risk factors. Insights into the mechanisms by which plasma ADMA is regulated may lead to new therapeutic knowledge.

Transplant allograft vasculopathy: Role of multimodality imaging in surveillance and diagnosis

Cardiac allograft vasculopathy (CAV) is a challenging long-term complication of cardiac transplantation and remains a leading long-term cause of graft failure, re-transplantation, and death. CAV is an inflammatory vasculopathy distinct from traditional atherosclerotic coronary artery disease. Historically, the surveillance and diagnosis of CAV has been dependent on serial invasive coronary angiography with intravascular imaging. Although commonly practiced, angiography is not without significant limitations. Technological advances have provided sophisticated imaging techniques for CAV assessment. It is now possible to assess the vascular lumen, vessel wall characteristics, absolute blood flow, perfusion reserve, myocardial contractile function, and myocardial metabolism and injury in a noninvasive, expeditious manner with little risk. The current article will review key imaging modalities for the surveillance, diagnosis, and prognosis of CAV and discuss coronary physiology of transplanted hearts with emphasis on the clinical implications for provocative and vasodilator stress testing.

Platelet-derived Growth Factor-B Protects Rat Cardiac Allografts From Ischemia-reperfusion Injury

BACKGROUND

Microvascular dysfunction and cardiomyocyte injury are hallmarks of ischemia-reperfusion injury (IRI) after heart transplantation. Platelet-derived growth factors (PDGF) have an ambiguous role in this deleterious cascade. On one hand, PDGF may exert vascular stabilizing and antiapoptotic actions through endothelial-pericyte and endothelial-cardiomyocyte crosstalk in the heart; and on the other hand, PDGF signaling mediates neointimal formation and exacerbates chronic rejection in cardiac allografts. The balance between these potentially harmful and beneficial actions determines the final outcome of cardiac allografts.

METHODS AND RESULTS

We transplanted cardiac allografts from Dark Agouti rat and Balb mouse donors to fully major histocompatibility complex-mismatched Wistar Furth rat or C57 mouse recipients with a clinically relevant 2-hour cold ischemia and 1-hour warm ischemia. Ex vivo intracoronary delivery of adenovirus-mediated gene transfer of recombinant human PDGF-BB upregulated messenger RNA expression of anti-mesenchymal transition and survival factors BMP-7 and Bcl-2 and preserved capillary density in rat cardiac allografts at day 10. In mouse cardiac allografts PDGF receptor-β, but not -α intragraft messenger RNA levels were reduced and capillary protein localization was lost during IRI. The PDGF receptor tyrosine kinase inhibitor imatinib mesylate and a monoclonal antibody against PDGF receptor-α enhanced myocardial damage evidenced by serum cardiac troponin T release in the rat and mouse cardiac allografts 6 hours after reperfusion, respectively. Moreover, imatinib mesylate enhanced rat cardiac allograft vasculopathy, cardiac fibrosis, and late allograft loss at day 56.

CONCLUSIONS

Our results suggest that PDGF-B signaling may play a role in endothelial and cardiomyocyte recovery from IRI after heart transplantation.

Ribonuclease (RNase) Prolongs Survival of Grafts in Experimental Heart Transplantation

BACKGROUND

Cell damage, tissue and vascular injury are associated with the exposure and release of intracellular components such as RNA, which promote inflammatory reactions and thrombosis. Based on the counteracting anti-inflammatory and cardioprotective functions of ribonuclease A (RNase A) in this context, its role in an experimental model of heart transplantation in rats was studied.

METHODS AND RESULTS

Inbred BN/OrlRj rat cardiac allografts were heterotopically transplanted into inbred LEW/OrlRj rats. Recipients were intravenously treated every other day with saline or bovine pancreatic RNase A (50 μg/kg). Toxic side effects were not found (macroscopically and histologically). Heart tissue flow cytometry and quantitative morphological analyses of explanted hearts at postoperative day 1 or postoperative day 4 showed reduced leukocyte infiltration, edema, and thrombus formation in RNase A-treated rats. In allogeneic mixed lymphocyte reactions, RNase A decreased the proliferation of effector T cells. RNase A treatment of rats resulted in prolonged median graft survival up to 10.5 days (interquartile range 1.8) compared to 6.5 days (interquartile range 1.0) in saline treatment (P=0.001). Treatment of rats with a new generated (recombinant) human pancreatic RNase 1 prolonged median graft survival similarly, unlike treatment with (recombinant) inactive human RNase 1 (each 50 μg/kg IV every other day, 11.0 days, interquartile range 0.3, versus 8.0 days, interquartile range 0.5, P=0.007).

CONCLUSIONS

Upon heart transplantation, RNase administration appears to present a promising and safe drug to counteract ischemia/reperfusion injury and graft rejection. Furthermore, RNase treatment may be considered in situations of critical reperfusion after percutaneous coronary interventions or in cardiac surgery using the heart-lung machine.

Avoidance of Profound Hypothermia During Initial Reperfusion Improves the Functional Recovery of Hearts Donated After Circulatory Death

The resuscitation of hearts donated after circulatory death (DCD) is gaining widespread interest; however, the method of initial reperfusion (IR) that optimizes functional recovery has not been elucidated. We sought to determine the impact of IR temperature on the recovery of myocardial function during ex vivo heart perfusion (EVHP). Eighteen pigs were anesthetized, mechanical ventilation was discontinued, and cardiac arrest ensued. A 15-min standoff period was observed and then hearts were reperfused for 3 min at three different temperatures (5°C; N = 6, 25°C; N = 5, and 35°C; N = 7) with a normokalemic adenosine-lidocaine crystalloid cardioplegia. Hearts then underwent normothermic EVHP for 6 h during which time myocardial function was assessed in a working mode. We found that IR coronary blood flow differed among treatment groups (5°C = 483 ± 53, 25°C = 722 ± 60, 35°C = 906 ± 36 mL/min, p < 0.01). During subsequent EVHP, less myocardial injury (troponin I: 5°C = 91 ± 6, 25°C = 64 ± 16, 35°C = 57 ± 7 pg/mL/g, p = 0.04) and greater preservation of endothelial cell integrity (electron microscopy injury score: 5°C = 3.2 ± 0.5, 25°C = 1.8 ± 0.2, 35°C = 1.7 ± 0.3, p = 0.01) were evident in hearts initially reperfused at warmer temperatures. IR under profoundly hypothermic conditions impaired the recovery of myocardial function (cardiac index: 5°C = 3.9 ± 0.8, 25°C = 6.2 ± 0.4, 35°C = 6.5 ± 0.6 mL/minute/g, p = 0.03) during EVHP. We conclude that the avoidance of profound hypothermia during IR minimizes injury and improves the functional recovery of DCD hearts.

Post-heart transplant complications

Managing patients after heart transplantation is challenging, since these patients have unique clinical complications (associated with the immunosuppressive therapy and cardiac allograft rejection) together with atypical clinical presentations for infection and systemic inflammatory response syndrome. Survival rates have improved substantially with the use of new immunosuppressive drugs. High vigilance, early diagnosis, and appropriate intervention for allograft-related and non-allograft-related syndromes with significant morbidity and mortality are the keys to long-term survival of patients after transplantation.

Reduced progression of cardiac allograft vasculopathy with routine use of induction therapy with basiliximab

Background

Cardiac allograft vasculopathy (CAV) is a major limitation for long-term survival of patients undergoing heart transplantation (HT). Some immunosuppressants can reduce the risk of CAV.

Objectives

The primary objective was to evaluate the variation in the volumetric growth of the intimal layer measured by intracoronary ultrasound (IVUS) after 1 year in patients who received basiliximab compared with that in a control group.

Methods

Thirteen patients treated at a single center between 2007 and 2009 were analyzed retrospectively. Evaluations were performed with IVUS, measuring the volume of a coronary segment within the first 30 days and 1 year after HT. Vasculopathy was characterized by the volume of the intima of the vessel.

Results

Thirteen patients included (7 in the basiliximab group and 6 in the control group). On IVUS assessment, the control group was found to have greater vessel volume (120–185.43 mm³ vs. 127.77–131.32 mm3; p = 0.051). Intimal layer growth (i.e., CAV) was also higher in the control group (27.30–49.15 mm³ [∆80%] vs. 20.23–26.69 mm³ [∆33%]; p = 0.015). Univariate regression analysis revealed that plaque volume and prior atherosclerosis of the donor were not related to intima growth (r = 0.15, p = 0.96), whereas positive remodeling was directly proportional to the volumetric growth of the intima (r = 0.85, p < 0.001).

Conclusion

Routine induction therapy with basiliximab was associated with reduced growth of the intima of the vessel during the first year after HT.

Coronary microvasculopathy in heart transplantation: Consequences and therapeutic implications

Despite the progress made in the prevention and treatment of rejection of the transplanted heart, cardiac allograft vasculopathy (CAV) remains the main cause of death in late survival transplanted patients. CAV consists of a progressive diffuse intimal hyperplasia and the proliferation of vascular smooth muscle cells, ending in wall thickening of epicardial vessels, intramyocardial arteries (50-20 μm), arterioles (20-10 μm), and capillaries (< 10 μm). The etiology of CAV remains unclear; both immunologic and non-immunologic mechanisms contribute to endothelial damage with a sustained inflammatory response. The immunological factors involved are Human Leukocyte Antigen compatibility between donor and recipient, alloreactive T cells and the humoral immune system. The non-immunological factors are older donor age, ischemia-reperfusion time, hyperlipidemia and CMV infections. Diagnostic techniques that are able to assess microvascular function are lacking. Intravascular ultrasound and fractional flow reserve, when performed during coronary angiography, are able to detect epicardial coronary artery disease but are not sensitive enough to assess microvascular changes. Some authors have proposed an index of microcirculatory resistance during maximal hyperemia, which is calculated by dividing pressure by flow (distal pressure multiplied by the hyperemic mean transit time). Non-invasive methods to assess coronary physiology are stress echocardiography, coronary flow reserve by transthoracic Doppler echocardiography, single photon emission computed tomography, and perfusion cardiac magnetic resonance. In this review, we intend to analyze the mechanisms, consequences and therapeutic implications of microvascular dysfunction, including an extended citation of relevant literature data.

Effect of everolimus on the immunomodulation of the human neutrophil inflammatory response and activation

The primary cause of mortality at 5 years following a cardiac transplantation is the development of atherosclerosis, termed coronary allograft vasculopathy (CAV). This pathology is characterized by diffused intimal hyperplasia and emanates from coronary arterial injuries caused by immune inflammatory cells. Neutrophils play an important role in this inflammatory process; however, their potential participation in the pathogenesis of CAV is poorly understood. Despite their essential contribution to the prevention of graft rejection, immunosuppressive drugs could have detrimental effects owing to their pro-inflammatory activities. Thus, we investigated the impact of different immunosuppressive drugs on the inflammatory response of neutrophils isolated from the blood of healthy volunteers. Under basal conditions, mammalian target of rapamycin (mTOR) inhibitors (sirolimus and everolimus) had the most potent anti-inflammatory effect, decreasing both IL-8 release (≈−80%) and vascular endothelial growth factor (VEGF) release (≈−65%) and preserving the release of the anti-inflammatory cytokine interleukin-1 receptor antagonist (IL-1RA). In TNF-α-treated neutrophils, pre-incubation with everolimus provided the most potent effect, simultaneously reducing the release of both VEGF and IL-8 while doubling the release of IL-1RA. This latter effect of everolimus was maintained even when administered in combination with other immunosuppressive drugs. Sirolimus and everolimus decreased the tumor necrosis factor (TNF)-α-induced adhesion of neutrophils to human endothelial cells and human extracellular matrix. This effect was largely dependent on the ability of these compounds to alter β₂-integrin/CD18 activation. Our results suggest a potential mechanism for the beneficial effect of everolimus in the prevention of CAV in heart transplant recipients.

The Role of Ectonucleotidases CD39 and CD73 and Adenosine Signaling in Solid Organ Transplantation

Extracellular adenosine is a potent immunomodulatory molecule that accumulates in states of inflammation. Nucleotides such as adenosine triphosphate and adenosine diphosphate are release from injured and necrotic cells and hydrolyzed to adenosine monophosphate and adenosine by the concerted action of the ectonucleotidases CD39 and CD73. Accumulating evidence suggest that purinergic signaling is involved in the inflammatory response that accompanies acute rejection and chronic allograft dysfunction. Modification of the purinergic pathway has been shown to alter graft survival in a number of solid organ transplant models and the response to ischemia–reperfusion injury (IRI). Furthermore, the purinergic pathway is intrinsically involved in B and T cell biology and function. Although T cells have traditionally been considered the orchestrators of acute allograft rejection, a role for B cells in chronic allograft loss is being increasingly appreciated. This review focuses on the role of the ectonucleotidases CD39 and CD73 and adenosine signaling in solid organ transplantation including the effects on IRI and T and B cell biology.

Should we consider patients with coexistent hepatitis B or C infection for orthotopic heart transplantation?

Heart transplantation (HTX) is the gold standard surgical treatment for patients with advanced heart failure. The prevalence of hepatitis B and hepatitis C infection in HTX recipients is over 10%. Despite its increased prevalence, the long-term outcome in this cohort is still not clear. There is a reluctance to place these patients on transplant waiting list given the increased incidence of viral reactivation and chronic liver disease after transplant. The emergence of new antiviral therapies to treat this cohort seems promising but their long-term outcome is yet to be established. The aim of this paper is to review the literature and explore whether it is justifiable to list advanced heart failure patients with coexistent hepatitis B/C infection for HTX.

Endothelium and Regulatory Inflammatory Mechanisms During Organ Rejection

Endothelial integrity is mandatory for physiologic organ function; however, endothelium dysfunction can be caused by systemic inflammation, occurring during sepsis or organ rejection after transplantation. This article will address our current understanding of endothelial involvement in organ transplantation and rejection. Overall, more detailed studies focusing on the endothelial modulation after organ transplantation would be necessary to investigate the role of endothelium activation during organ rejection.

Differential effect of everolimus on progression of early and late cardiac allograft vasculopathy in current clinical practice

Randomized trials showed that mTOR inhibitors prevent early development of cardiac allograft vasculopathy (CAV). However, the action of these drugs on CAV late after transplant is controversial, and their effectiveness for CAV prevention in clinical practice is poorly explored. In this observational study we included 143 consecutive heart transplant recipients who underwent serial intravascular ultrasound (IVUS), receiving either everolimus or mycophenolate as adjunctive therapy to cyclosporine. Ninety-one recipients comprised the early cohort, receiving IVUS at weeks 3-6 and year 1 after transplant, and 52 the late cohort, receiving IVUS at years 1 and 5 after transplant. Everolimus independently reduced the odds for early CAV (0.14 [0.01-0.77]; p = 0.02) but it did not appear to influence late CAV progression. High-dose statins were found to be associated with reduced CAV progression both early and late after transplant (p ≤ 0.05). Metabolic abnormalities, such as high triglycerides, were associated with late, but not with early CAV progression. By highlighting a differential effect of everolimus and metabolic abnormalities on early and late changes of graft coronary morphology, this observational study supports the hypothesis that everolimus may be effective for CAV prevention but not for CAV treatment, and that risk factors intervene in a time-dependent sequence during CAV development.

Endothelial dysfunction and cardiac allograft vasculopathy

Cardiac allograft vasculopathy remains a major challenge to long-term survival after heart transplantation. Endothelial injury and dysfunction, as a result of multifactorial immunologic and nonimmunologic insults in the donor and the recipient, are prevalent early after transplant and may be precursors to overt cardiac allograft vasculopathy. Current strategies for managing cardiac allograft vasculopathy, however, rely on the identification and treatment of established disease. Improved understanding of mechanisms leading to endothelial dysfunction in heart transplant recipients may provide the foundation for the development of sensitive screening techniques and preventive therapies.

Virtual histology assessment of cardiac allograft vasculopathy following introduction of everolimus--results of a multicenter trial

In this 12-month multicenter Scandinavian study, 78 maintenance heart transplant (HTx) recipients randomized to everolimus with reduced calcineurin inhibitor (CNI) exposure or continued standard CNI-therapy underwent matched virtual histology (VH) examination to evaluate morphological progression of cardiac allograft vasculopathy (CAV). Parallel measurement of a range of inflammatory markers was also performed. A similar rate of quantitative CAV progression was observed in the everolimus (n = 30) and standard CNI group (n = 48) (plaque index 1.9 ± 3.8% and 1.6 ± 3.9%, respectively; p = 0.65). However, VH analysis revealed a significant increase in calcified (2.4 ± 4.0 vs. 0.3 ± 3.1%; p = 0.02) and necrotic component (6.5 ± 8.5 vs. 1.1 ± 8.6%; p = 0.01) among everolimus patients compared to controls. The increase in necrotic and calcified components was most prominent in everolimus patients with time since HTx >5.1 years and was accompanied by a significant increase in levels of von Willebrand (vWF) factor (p = 0.04) and vascular cell adhesion molecule (VCAM) (p = 0.03). Conversion to everolimus and reduced CNI is associated with a significant increase in calcified and necrotic intimal components and is more prominent in patients with a longer time since HTx. A significant increase in vWF and VCAM accompanied these qualitative changes and the prognostic implication of these findings requires further investigation.

Influence of smoking cessation on carotid artery wall elasticity evaluated by echo-tracking

OBJECTIVE

Exploring the use of echo-tracking (ET) for evaluating changes in carotid artery wall elasticity after smoking cessation.

METHODS

Carotid artery ultrasound examination was performed in 67 male patients before and after smoking cessation treatment, for measurement of intimal media thickness (IMT), and ET measurement of wall elasticity variables, ie, wall stiffness index (β), pressure-strain elastic modulus (Ep), compliance (AC), augmentation index (AI), and local pulse wave velocity (PWVβ). We also measured heart rate (HR), systolic pressure (Ps), diastolic pressure (Pd), total cholesterol (TC), triglyceride level (TG), low-density lipoprotein (LDL), and high-density lipoprotein (HDL).

RESULTS

Hyperlipemia and/or arterial hypertension and/or hyperglycemia were absent in 22 (group A1) and 12 (group B1) and present in 19 (group A2) and 14 (group B2) of the patients with successful (group A, n = 41) and unsuccessful (group B, n = 26) treatment, respectively. In the A1 group, there was no significant difference in AI before and after smoking cessation, whereas β, Ep, and PWVβ decreased, and AC increased (p < 0.05). None of these variables changed after smoking cessation in groups A2, B1, and B2. There was no change in IMT in either group. HR decreased and HDL increased in the A1 group, without change in Ps, Pd, TC, TG, and LDL. There was no change in HR, Ps, Pd, TC, TG, LDL, and HDL in groups A2, B1, and B2.

CONCLUSIONS

ET can be used to evaluate quantitatively the impact of smoking cessation on common carotid artery wall elasticity.

Novel control of cAMP-regulated transcription in vascular endothelial cells

Chronic inflammatory diseases, such as atherosclerosis, are a major cause of death and disability in the developed world. In this respect, although cholesterol obviously plays a predominant role in atherosclerosis, targeting inflammation at lesion sites may be just as important. Indeed, elevated IL-6 (interleukin 6) levels are as strongly associated with coronary heart disease as increased cholesterol. We have been investigating novel cAMP-regulated pathways that combat the action of pro-inflammatory cytokines, such as IL-6 and leptin, in the VECs (vascular endothelial cells) of the circulatory system. In this respect, we have begun to unravel new molecular mechanisms by which the cAMP/Epac1 (exchange protein directly activated by cAMP 1)/Rap1 pathway can initiate a rigorous programme of protective anti-inflammatory responses in VECs. Central to this is the coupling of cAMP elevation to the mobilization of two C/EBP (CCAAT/enhancer-binding protein) family transcription factors, resulting in the induction of the SOCS3 (suppressor of cytokine signalling 3) gene, which attenuates pro-inflammatory cytokine signalling in VECs. These novel 'protective' mechanisms of cAMP action will inform the development of the next generation of pharmaceuticals specifically designed to combat endothelial inflammation associated with cardiovascular disease.