Immunosuppression and transplant vascular disease: benefits and adverse effects

Effect of Statin Intensity on the Progression of Cardiac Allograft Vasculopathy

Background: In the non-transplant population, hyperlipidaemia has shifted from targeting LDL goals to statin intensity-based treatment. It is unknown whether this strategy is also beneficial in cardiac transplantation. Methods: This single-centre retrospective study evaluated the effect of statin use and intensity on time to cardiac allograft vasculopathy (CAV) after cardiac transplantation. Kaplan–Meier and Cox proportional hazards regression survival methods were used to assess the association of statin intensity and median post-transplant LDL on CAV-free survival. Results: The study involved 143 adults (71% men, average follow-up of 25 ± 14 months) who underwent transplant between 2013 and 2017. Mean CAV-free survival was 47.5 months (95% CI [43.1–51.8]), with 29 patients having CAV grade 1 or greater. Median LDL was not associated with time to CAV (p=0.790). CAV-free survival did not differ between intensity groups (p=0.435). Conclusion: Given the non-statistically significant difference in time to CAV with higher intensity statins, the data suggest that advancing moderate- or high-intensity statin after cardiac transplantation may not provide additional long-term clinical benefit. Trial registration: Not applicable.

Adverse Effects of Immunosuppression: Nephrotoxicity, Hypertension, and Metabolic Disease

The use of Immunosuppression has led to the tremendous improvement in graft survival. However, immunosuppressants have been found to cause a variety of metabolic derangements including but not limited to: insulin resistance and diabetes, hyperlipidemia, hypertension, and weight gain after transplantation. This combination of metabolic risk factors may be associated with increased cardiovascular disease (Grundy et al., Circulation 112(17):2735, 2005). In addition many transplant recipients may have many of these risk factors pre-transplant that are exacerbated by immunosuppression. These facts emphasize the need for rigorous follow-up and management of these risk factors post-transplant.The most common immune suppressant regimens may include different combinations of these agents: Corticosteroids, Calcineurin inhibitors (CNIs), Mammalian Target of Rapamycin (mTOR) Inhibitors, Antimetabolite.

Impact of tacrolimus versus cyclosporin A on renal function during the first year after heart transplant

AIMS

Nephrotoxicity of calcineurin inhibitors (CNIs) is associated with adverse events in patients undergoing heart transplant (HTx), although studies directly comparing tacrolimus (TAC) versus cyclosporin A (CsA), especially in combination with everolimus and low-dose CNIs approach, are limited. Thus, we sought to investigate the associations of TAC and CsA with clinical outcomes in HTx recipients, with specific focus on renal function.

METHODS AND RESULTS

From August 2007 to February 2017, 72 consecutive patients (39 treated with TAC vs. 33 with CsA) receiving de novo HTx in a single transplant centre were retrospectively evaluated. We used the instrumental variable method to account for unmeasured confounding. The study outcomes were percentage change in estimated glomerular filtration rates (eGFR) (safety endpoint) and biopsy-proven acute rejection (efficacy endpoint) within the first year after HTx. The enrolled patients (median age 40 years) were predominantly men (68%). There were no significant differences in baseline characteristics, including eGFR (64.8 [45.7-96.4] mL/min/1.73 m² in TAC vs. 65.6 [57.9-83.0] mL/min/1.73 m² for CsA; P = 0.48), other than sex (male, 49% for TAC vs. 91% for CsA; P < 0.001) between the two groups. Within the first year after HTx, 23 (59%) in the TAC group switched mycophenolate mofetil to everolimus, whereas 16 (48%) in the CsA group (P = 0.52). At 12 months, the rates of mortality and end-stage renal disease requiring renal replacement therapies were both 0%. In the instrumental variable analysis, no differences in renal function as well as graft rejection for 1 year after HTx existed between the TAC and CsA groups. These results were similar when taking into account of everolimus use.

CONCLUSIONS

Irrespective of everolimus use with low-dose CNIs, our analysis using the instrumental variable method showed no differences in renal function as well as graft rejection during the first year after HTx between HTx recipients who received TAC or CsA.

Hurdles to Cardioprotection in the Critically Ill

Cardiovascular disease is the largest contributor to worldwide mortality, and the deleterious impact of heart failure (HF) is projected to grow exponentially in the future. As heart transplantation (HTx) is the only effective treatment for end-stage HF, development of mechanical circulatory support (MCS) technology has unveiled additional therapeutic options for refractory cardiac disease. Unfortunately, despite both MCS and HTx being quintessential treatments for significant cardiac impairment, associated morbidity and mortality remain high. MCS technology continues to evolve, but is associated with numerous disturbances to cardiac function (e.g., oxidative damage, arrhythmias). Following MCS intervention, HTx is frequently the destination option for survival of critically ill cardiac patients. While effective, donor hearts are scarce, thus limiting HTx to few qualifying patients, and HTx remains correlated with substantial post-HTx complications. While MCS and HTx are vital to survival of critically ill cardiac patients, cardioprotective strategies to improve outcomes from these treatments are highly desirable. Accordingly, this review summarizes the current status of MCS and HTx in the clinic, and the associated cardiac complications inherent to these treatments. Furthermore, we detail current research being undertaken to improve cardiac outcomes following MCS/HTx, and important considerations for reducing the significant morbidity and mortality associated with these necessary treatment strategies.

Change in lymphocyte to neutrophil ratio predicts acute rejection after heart transplantation

AIMS

Most immunosuppressive drugs provide targeted immunosuppression by selective inhibition of lymphocyte activation and proliferation. This study evaluated whether a change in the lymphocyte to neutrophil ratio (LNR) is related to acute rejection.

METHODS

In 74 cardiac transplant recipients peripheral blood lymphocyte and neutrophil counts were measured soon after (baseline) and three, six, and 12months after heart transplantation. The primary endpoint was the incidence of acute rejection.

RESULTS

Significant acute rejection after heart transplantation occurred in 20 patients (27%) during a median follow-up of 49.4 [IQR 37.4-61.1] months. LNR significantly increased over time (0.1149±0.1354 at baseline, 0.2330±0.2266 at 3months, 0.2961±0.2849 at 6months, and 0.3521±0.2383 at 12months; P<0.001), especially during the first 3months in the group without acute rejection. The area under the curve of the change in LNR during the first three months (ΔLNR) for acute rejection was 0.565 (95% CI 0.420 to 0.710, P=0.380) on ROC curve analysis. The best cutoff value of Δ LNR to differentiate those with and without acute rejection was ≤0.046 by ROC curve analysis. Kaplan-Meier analysis revealed that the low ΔLNR group (≤0.046) had a significantly higher rate of acute rejection than the high ΔLNR group (>0.046) (37.5% vs. 19.0%, log-rank: P=0.0358). The low ΔLNR for the first 3months was an independent predictor of clinically significant acute rejection after adjusting for cytomegalovirus donor seropositive and recipient seronegative.

CONCLUSIONS

The results of this study suggest that ΔLNR over the first 3months after heart transplantation is a strong and independent predictor of acute rejection after heart transplantation. ΔLNR can be used as an early biomarker for predicting of acute rejection after heart transplantation.

Assessment of sub-clinical acute cellular rejection after heart transplantation: comparison of cardiac magnetic resonance imaging and endomyocardial biopsy

OBJECTIVE

Comparing the diagnostic value of multi-sequential cardiac magnetic resonance imaging (CMR) with endomyocardial biopsy (EMB) for sub-clinical cardiac allograft rejection.

METHODS

One hundred and forty-six examinations in 73 patients (mean age 53 ± 12 years, 58 men) were performed using a 1.5 Tesla system and compared to EMB. Examinations included a STIR (short tau inversion recovery) sequence for calculation of edema ratio (ER), a T1-weighted spin-echo sequence for assessment of global relative enhancement (gRE), and inversion-recovery sequences to visualize late gadolinium enhancement (LGE). Histological grade ≥1B was considered relevant rejection.

RESULTS

One hundred and twenty-seven (127/146 = 87 %) EMBs demonstrated no or mild signs of rejection (grades ≤1A) and 19/146 (13 %) a relevant rejection (grade ≥1B). Sensitivity, specificity, positive predictive, and negative predictive values were as follows: ER: 63 %, 78 %, 30 %, and 93 %; gRE: 63 %, 70 %, 24 %, and 93 %; LGE: 68 %, 36 %, 13 %, and 87 %; with the combination of ER and gRE with at least one out of two positive: 84 %, 57 %, 23 %, and 96 %. ROC analysis revealed an area under the curve of 0.724 for ER and 0.659 for gRE.

CONCLUSION

CMR parameters for myocarditis are useful to detect sub-clinical acute cellular rejection after heart transplantation. Comparable results to myocarditis can be achieved with a combination of parameters.

KEY POINTS

• Magnetic resonance imaging is useful for the assessment of cardiac allograft rejection. • CMR has a high negative predictive value for exclusion of allograft rejection. • Diagnostic performance is not yet good enough to replace endomyocardial biopsy.

Use of antioxidants to prevent cyclosporine a toxicity

Cyclosporine A (CsA) is a potent immunosuppressor that is widely used in transplant surgery and the treatment of several autoimmune diseases. However, major side effects of CsA such as nephrotoxicity, hepatotoxicity, neurotoxicity and cardiovascular diseases have substantially limited its usage. Although molecular mechanisms underlying these adverse effects are not clearly understood, there is some evidence that suggests involvement of reactive oxygen species (ROS) . In parallel, protective effects of various antioxidants have been demonstrated by many research groups. Extensive studies of CsA-induced nephrotoxcity have confirmed that the antioxidants can restore the damaged function and structure of kidney. Subsequently, there have appeared numerous reports to demonstrate the positive antioxidant effects on liver and other organ damages by CsA. It may be timely to review the ideas to envisage the relationship between ROS and the CsA-induced toxicity. This review is comprised of a brief description of the immunosuppressive action and the secondary effects of CsA, and a synopsis of reports regarding the antioxidant treatments against the ROS-linked CsA toxicity. A plethora of recent reports suggest that antioxidants can help reduce many CsA’s adverse effects and therefore might help develop more effective CsA treatment regimens.

Astilbin inhibits proliferation of rat aortic smooth muscle cells induced by angiotensin II and down-regulates expression of protooncogene

This study examined the effect of astilbin on the proliferation of rat aortic smooth muscle cells (RASMCs) induced by angiotensin II (AngII) and explored the possible mechanisms. Cell proliferation model of RASMCs was induced by treatmente with AngII. Cells were randomly divided to 8 groups. Normally cultured VSMCs serves as blank control group; in AngII model group, cells were treated with AngII at 10(-7) mol/L; in three astilbin groups, cells were treated with 10, 15, 30 mg/L of astilbin; in three AngII+astilbin groups, cells were treated with AngII (at 10(-7) mol/L) and astilbin at 10, 15, 30 mg/L. Cell proliferation ability was detected by MTT method and the cell cycles and proliferation index were flow cytometrically determined. The expression of c-myc mRNA was assessed by using reverse transcription polymerase chain reaction (RT-PCR), and the expression of NF-κB in RASMCs was immunocytochemically observed. Our results showed that MTT metabolism in RASMCs in the basic and AngII stimulated situation was inhibited by astilbin, and the cells numbers of G(0)/G(1) phase were increased and that of G(2)/S phase were decreased markedly. Not only highly expression of c-myc gene stimulated by AngII could be inhibited by Astilbin significantly, but also the expression of NF-κB protein can be down regulated by Astilbin. We are led to conclude that astilbin astilbin can inhibit the AngII-mediated proliferation of RASMCs by blocking the transition of RASMCs from G(0)/G(1) phase to S phase and by down-regulating the expression of NF-κB, c-myc gene.

Immunological advantages of everolimus versus cyclosporin A in liver-transplanted recipients, as revealed by polychromatic flow cytometry

Several immunosuppressive drugs with different mechanisms of action are available to inhibit organ rejection after transplant. We analyzed different phenotypic and functional immunological parameters in liver-transplanted patients who received cyclosporin A (CsA) or Everolimus (Evr). In peripheral blood mononuclear cells (PBMC) from 29 subjects receiving a liver transplant and treated with two different immunosuppressive regimens, we analyzed T cell activation and differentiation, regulatory T cells (Tregs) and Tregs expressing homing receptors such as the chemokine receptor CXCR3. T cell polyfunctionality was studied by stimulating cells with the superantigen staphylococcal enterotoxin B (SEB), and measuring the simultaneous production of interleukin (IL)-2 and interferon (IFN)-γ, along with the expression of a marker of cytotoxicity such as CD107a. The analyses were performed by polychromatic flow cytometry before transplantation, and at different time points, up to 220 days after transplant. Patients taking Evr had a higher percentage of total CD4⁺ and naïve CD4⁺ T cells than those treated with CsA; the percentage of CD8⁺ T cells was lower, but the frequency of naïve CD8⁺ T cells higher. Patients taking Evr showed a significantly higher percentage of Tregs, and Tregs expressing CXCR3. After stimulation with SEB, CD8⁺ T cells from Evr-treated patients displayed a lower total response, and less IFN-γ producing cells. The effects on the immune system, such as the preservation of the naïve T cell pool and the expansion of Tregs (that are extremely useful in inhibiting organ rejection), along with the higher tolerability of Evr, suggest that this drug can be safely used after liver transplantation, and likely offers immunological advantages.

Epidermal Growth Factor–Like Domain 7 Is a Novel Inhibitor of Neutrophil Adhesion to Coronary Artery Endothelial Cells Injured by Calcineurin Inhibition

Background—

We investigated the effect of epidermal growth factor–like domain 7 (Egfl7) on nuclear factor-κB activation, intercellular adhesion molecule-1 expression, and neutrophil adhesion to human coronary artery endothelial cells after calcineurin-inhibition–induced injury.

Methods and Results—

Human coronary endothelial cells were incubated with cyclosporine (CyA) 10 μg/mL with or without Egfl7 (100 ng/mL) or the Notch receptor activator Jagged1 (200 ng/mL) for 6 to 48 hours. CyA upregulated nuclear factor-κB (p65) activity (128±2% of control, P <0.001) in nuclear extracts, as determined with a DNA-binding activity ELISA. This activity was inhibited by Egfl7 (86±3% of control; P <0.001 versus CyA alone). Jagged1 blocked Egfl7-induced nuclear factor-κB inhibition (105±4% of control; P <0.05 versus CyA plus Egfl7). CyA upregulated cell-surface intercellular adhesion molecule-1 expression (215±13% of control; P <0.001), as determined by flow cytometry. This expression was suppressed by Egfl7 (148±5%; P <0.001 versus CyA alone). Jagged1 attenuated the intercellular adhesion molecule-1–suppressive effect of Egfl7 when administered with CyA (193±3% versus 148±5%; P <0.01). CyA increased neutrophil adhesion to human coronary endothelial cells (control 20±5%, CyA 37±3%; P <0.001 versus control) in a nonstatic neutrophil adhesion assay. This increase was attenuated by Egfl7 (22±6%; P <0.001 versus CyA alone). Jagged 1 attenuated the effect of Egfl7 on neutrophil adhesion (31±3%; P <0.001 versus Egfl7 plus CyA).

Conclusions—

Our study reveals that Egfl7 is a potent inhibitor of neutrophil adhesion to human coronary endothelial cells subsequent to calcineurin-inhibition–induced injury. Mechanistically, Egfl7 blocked nuclear factor-κB pathway activation and intercellular adhesion molecule-1 expression, which suggests that it may have significant antiinflammatory properties. Because Jagged1 blocked the effect of Egfl7, Notch receptor antagonism may contribute to the mechanism of action of Egfl7.

Chronic treatment with cyclosporine affects systemic purinergic parameters, homocysteine levels and vascular disturbances in rats

Vascular disease is a major cause of morbidity and mortality among transplanted recipients and cyclosporine (CsA) treatment has been consistently implicated in this event. In this study we assessed total blood homocysteine levels (tHcy), ecto-nucleotidase activities and adenine nucleotide/nucleoside levels searching for parameters related to the mechanisms of vascular damage induced by chronic CsA treatment in non-transplanted rats. Thirty male Wistar rats were divided in three groups: control group treated with corn oil, CsA 5mg/kg and CsA 15 mg/kg, administered by daily gastric gavage during 8 weeks. CsA 15 mg/kg treatment increased blood levels of tHcy. Both CsA treatments (5mg/kg and 15 mg/kg) decreased adenine nucleotides hydrolysis by ecto-nucleotidases in serum, which negatively correlated with tHcy levels (r: -0.74, r: -0.63 and r: -0.63, p<0.004, for ATP, ADP and AMP, respectively). CsA 15mg/kg induced a statistically significant increase in ADP and decrease in adenosine (ADO) plasma levels compared to control group. THcy levels were positively correlated with plasma ADP levels and negatively correlated with ADO levels (r: 0.84, p<0.0001 and r: -0.68, p<0.0001, respectively). Rats under CsA 15 mg/kg treatment presented cell injury and inflammatory responses in the endothelium and intima layer of the aorta artery. In conclusion, blood ecto-nucleotidases activity, tHcy, and ADP and ADO levels may be implicated in vascular injury induced by CsA treatment.

Combination of clopidogrel and everolimus dramatically reduced the development of transplant arteriosclerosis in murine aortic allografts

Our group has shown that platelet inhibition with clopidogrel, an antagonist of the P2Y12 adenosine diphosphate receptor on platelets, reduced the formation of transplant arteriosclerosis. The aim of this study was to investigate whether a combination of cyclosporin or everolimus with clopidogrel has a beneficial effect on the development of transplant arteriosclerosis. Fully MHC mismatched C57Bl/6 (H2(b)) donor aortas were transplanted into CBA.J (H2(k)) recipients and mice received either clopidogrel alone (1 mg/kg/day) or in combination with cyclosporin (2 mg/kg/day) or everolimus (0.05 mg/kg/day). Grafts were analysed by histology and morphometry on day 30 after transplantation. In mice treated with clopidogrel alone, transplant arteriosclerosis was significantly reduced [intima proliferation 56 +/- 11% vs. 81 +/- 7% (control)/n = 7]. Daily application of everolimus reduced the development of transplant arteriosclerosis compared with untreated controls [intima proliferation of 29 +/- 9% vs. 81 +/- 7% (control)/n = 7]. Strikingly, combination of clopidogrel and everolimus almost abolished the formation of transplant arteriosclerosis [intima proliferation: 11 +/- 8% vs. 81 +/- 7% (control)/n = 7]. By contrast, combination of cyclosporin and clopidogrel compared with clopidogrel alone showed no additive effect. These results demonstrate that combination of platelet- and mammalian target of Rapamycin-inhibition can dramatically reduce the development of transplant arteriosclerosis.

T-helper 2 cells are essential for modulation of vascular repair by allogeneic endothelial cells

BACKGROUND

Endothelial cells (ECs) embedded within 3-dimensional matrices (MEEC) control lumenal inflammation and intimal hyperplasia when placed in the vascular adventitia. Matrix embedding alters endothelial immunogenicity in vitro. T-helper (Th) cell-driven host immunity is an impediment of allogeneic grafts. We aimed to identify if modulation of Th balance would affect immune compatibility and endothelial regulation of vascular repair in vivo.

METHODS

Pigs (n = 4/group) underwent carotid artery balloon injury and were left untreated (Group 1) or received perivascular porcine MEEC implants (Group 2), 12 days of cyclosporine A (CsA; Group 3), or MEEC and CsA (Group 4). Host immune reactivity was analyzed after 28 and 90 days.

RESULTS

MEEC treatment induced formation of EC-specific immunoglobulin (Ig) G(1) antibodies (41 +/- 6 mean fluorescence intensity [MFI]) and differentiation of host splenocytes into Th2, but not Th1, cytokine-producing cells (interleukin [IL]-4, 242 +/- 102; IL-10, 273 +/- 114 number of spots). Concomitant CsA therapy reduced IgG(1) antibody frequency (25 +/- 2 MFI; p < 0.02) and Th2-cytokine producing splenocytes upon MEEC treatment (IL-4, 157 +/- 19; IL-10, 124 +/- 26 number of spots; p < 0.05). MEECs inhibited luminal occlusion 28 and 90 days after balloon injury (12 +/- 7%) vs untreated controls (68 +/- 14%; p < 0.001) but to a lesser extent with concomitant CsA treatment (34 +/- 13%; p < 0.02 vs Group 2).

CONCLUSIONS

MEECs do not induce a significant Th1-driven immune response but do enhance differentiation of splenocytes into cells producing Th2 cytokine. Reduction in this Th2 response reduces the vasoregulatory effects of allogeneic ECs after injury.

The inhibitory effect of astilbin on the arteriosclerosis of murine thoracic aorta transplant

The inhibitory effect of astilbin on transplant arteriosclerosis in murine model of thoracic aorta transplantation was examined. Model of rat thoracic aorta transplantation was established. Ninety rats were divided into three groups. In isograft group, the thoracic aorta of Brown Norway (BN) rat was anastomosed with the abdominal aorta of another BN rat. In allograft group, the thoracic aorta of BN rat was anastomosed with the abdominal aorta of Lewis rat. In astilbin group, the rats receiving allo-transplantation were given astilbin 5 mg/kg per day for a time of 28 days. The donor thoracic aorta and the recipient abdominal aorta were anastomosed by means of a polyethylene cannula (inner diameter: 1.5 mm, length: 3 mm length). The grafts were histologically examined for structural changes. The areas of arterial lumen and endatrium were calculated. Our results showed that, in the allograft group, 28 days after allografting, conspicuous proliferation of smooth muscles and infiltration with a great number of inflammatory cells were found in the tunica intima and tunica media. Astilbin significantly inhibited the proliferation of smooth muscles and ameliorated the infiltration of inflammatory cells thereby prevent against the development of transplant arteriosclerosis. It is concluded that asltilbin can effectively prevent the development of arteriosclerosis in allotransplant by inhibiting the proliferation of smooth muscles and inhibit the proliferation of smooth muscles in tunica of intima and media and reducing infiltration of the inflammatory cells.

RETRACTED: Chronic cardiac allograft rejection in mice is alleviated by inhibition of CCR5 in combination with cyclosporine A

The chemokine receptor CCR5 plays important roles in acute allograft rejection. In this study, we examined the inhibition of CCR5 in combination with the treatment with cyclosporine A (CsA) in chronic rejection in cardiac transplantation. Forty-five transplant recipients were randomized to three groups. Recipients in group A were treated with anti-CCR5 mAb and CsA, mice in group B were given anti-CCR5 mAb alone, and animals in group C were administered with only CsA. On day 45 after transplantation, the allografts were harvested and examined by immunohistologic technique and PT-PCR methods. Allografts treated with anti-CCR5 mAb and CsA showed significantly prolonged survival (44.73 ± 0.258 days, P < 0.01) as compared with CsA-treated group (37.00 ± 2.04 days). Treatment with anti-CCR5 mAb plus CsA significantly inhibited the progression of cardiac allograft vasculopathy. Our findings demonstrated that anti-CCR5 mAb in combination with CsA can prolong the survival of allograft through their cardio-protective and immunomodulative properties. Thus, combined administration of anti-CCR5 mAb and CsA may become a new therapeutic approach for the prevention of cardiac graft failure that has not been obviated by conventional immunosuppressive agents.

Prevention and inhibition but not reversion of chronic allograft vasculopathy by FK778

BACKGROUND

This study aimed at investigating the efficacy of the novel immunosuppressant FK778 to prevent the development and progression of chronic allograft vasculopathy (CAV).

METHODS

Orthotopic aortic transplantations were performed in the PVG-to-ACI rat model and followed over the course of 120 days. Immunosuppression with FK778 (20 mg/kg) or sirolimus (2 mg/kg) was either started early or delayed when CAV was already present. Trough levels were monitored. Aortic luminal obliteration was quantified using computer morphometry and intragraft cytokine profiles were analyzed with Western Blotting. Donor-reactive antibodies were quantified by flow cytometry.

RESULTS

Untreated animals developed CAV with luminal obliteration of 25.2+/-13.6% and 41.4+/-23.3% after 80 and 120 days, respectively. Continuous immunosuppression with FK778 or sirolimus effectively prevented the development of vasculopathy. When the start of the immunosuppressive regimen was delayed until postoperative day 80, FK778 and sirolimus inhibited a progression of established CAV but did not reverse the luminal obliteration. Intragraft tumor growth factor-beta activity increased over the course of time in untreated recipients but was significantly suppressed after continuous immunosuppression with either agent. Expression of platelet-derived growth factor, intercellular adhesion molecule-1, and vascular adhesion molecule-1 also was moderately suppressed. A stable elevation of donor-reactive IgG-antibody levels was found over 120 days in the absence of treatment. With FK778 or sirolimus, antibody levels were effectively decreased. FK778 was very well tolerated and only sirolimus showed side effects with elevation of BUN, cholesterol, triglycerides, and ALT after 120 days.

CONCLUSIONS

FK778 prevents the development of CAV and inhibits a progression of established disease. It shows a similar efficacy but a safer drug profile when compared to sirolimus.

The influence of cyclosporin A on lymphocyte attenuator expression

B and T lymphocyte attenuator (BTLA), a recently identified immune inhibitory receptor, has been demonstrated to have the ability to maintain self-tolerance and transplant-tolerance in mice. However, little is known about the effects of immunosuppressive drugs on the expression of BTLA. In the present study, we observed that the immunosuppressive drug cyclosporin A (CsA) could significantly reduce BTLA but not CD25 and CD69 expression on CD4+ T cells during activation in vitro, while rapamycin (RPM) had little effect on it. Exogenous interleukin-2 (IL-2) failed to reverse the inhibitory effect that CsA had on BTLA expression. Furthermore, phorbol 12-myristate 13-acetate (PMA) or ionomycin alone could efficiently induce BTLA protein expression on CD4+ and CD8+ T cells, while CsA significantly suppressed BTLA expression in this system. The present data indicate that the regulation of BTLA expression on CD4+ T cells does not depend on IL-2 and T cell activation but depends on calcineurin-dependent and calcineurin-independent pathways. The observation that CsA significantly inhibits BTLA expression on CD4+ T cells during activation, suggests that CsA might block the immune tolerance induced by BTLA and potentially increase the susceptibility to autoimmune diseases and graft rejection.

Recommendations for the use of everolimus (Certican) in heart transplantation: results from the second German-Austrian Certican Consensus Conference

Everolimus (Certican; Novartis Pharma AG, Basel, Switzerland) represents the latest generation of proliferation signal inhibitors (PSIs). Everolimus is indicated for use as an immunosuppressive drug in renal and heart transplantation. This report reflects the recommendations of the second German-Austrian Certican Consensus Conference, held in January 2006, for the clinical use of everolimus.

Drugs modulating endothelial function after transplantation

Endothelial cells play a vital role in the success or failure of a transplant procedure. The procedure itself can be viewed as a series of insults that damages the endothelium thereby triggering an inflammatory cascade that may, if uncontrolled, drive the proliferative and fibrotic processes characteristic of chronic graft vasculopathy. Unfortunately, many immunosuppressant agents contribute to this process. Glucocorticoids and the calcineurin inhibitor cyclosporine induce endothelial dysfunction, and although tacrolimus may not have the same disruptive effects on endothelial function as cyclosporine, its endothelial activity is still being established. In contrast, antiproliferative agents slow the proliferation and migration of endothelial cells and so help protect against graft vasculopathy. Researchers agree that endothelial cell dysfunction is a potentially treatable stage in the multifactorial process of graft vasculopathy and rejection. A number of cardiovascular agents (statins, angiotensin converting enzyme inhibitors, calcium channel blockers), immunoregulatory drugs, and dietary compounds have been shown to have beneficial effects on endothelial function. We briefly review the evidence supporting their use as protection for endothelial cells in transplant recipients.

Inflammation and atherosclerosis: novel insights into plaque formation and destabilization

BACKGROUND AND PURPOSE

The simplistic view of atherosclerosis as a disorder of pathological lipid deposition has been redefined by the more complex concept of an ongoing inflammatory response.

SUMMARY OF REVIEW

Apolipoprotein E and low-density lipoprotein (LDL)-receptor-deficient mice develop accelerated atherosclerosis allowing in-depth pathophysiological investigations. Atherosclerotic plaques in these mice contain large numbers of T cells and macrophages. Crossbreeding apolipoprotein E-deficient mice with T-cell-deficient mice and mice with impaired macrophage function (osteopetrotic op/op mice) disclosed the important impact of immune cells on atherosclerotic lesion development. In contrast to the detrimental role of T cells and macrophages, B cells appear to be atheroprotective. These basic experimental findings have partly been confirmed in studies of the human carotid artery system. Inflammation is not only instrumental in the development of human atheromatous plaques, but, importantly, plays a crucial role in the destabilization of internal carotid artery plaques, thus converting chronic atherosclerosis into an acute thrombo-embolic disorder. Humoral factors involved in internal carotid artery destabilization include cytokines, cyclooxygenase-2, matrix metalloproteinases, and tissue factor. Antibodies to oxidized LDL can reflect disease activity on one hand, but can also confer atheroprotection. Novel MRI techniques may aid in the in vivo assessment of acute plaque inflammation in humans.

CONCLUSIONS

The impact of inflammation on the development of atherosclerotic plaques and their destabilization opens new avenues for treatment. The effects of statins, acetylsalicyclic acid and angiotensin-converting enzyme inhibitors on stroke prevention may partly be attributable to their profound anti-inflammatory actions. Vaccination against modified LDL and heat shock proteins halt plaque progression in experimental atherosclerosis. Their potential for prevention of human atherosclerosis is currently under investigation.

Contemporary concepts in prevention and treatment of cardiac allograft vasculopathy

Cardiac allograft vasculopathy (CAV), is characterized by heterogeneous proliferative thickening of the vascular intima of the cardiac allograft vasculature. Since its presentation is commonly clinically silent, early diagnosis and preventative therapy are critical. Preventative therapy including optimization of immunosuppressive therapy and treatment of comorbidities associated with CAV progression must be initiated early since most of the intimal thickening occurs during the first year posttransplant. Long-term use of calcineurin inhibitors is associated with a high incidence of chronic renal disease and also contributes to hyperlipidemia and hypertension, all of which may exacerbate CAV. In addition, statins, antihypertensive agents and anti-CMV agents all have demonstrated benefits in reducing CAV. Once established, the limited treatment options include nonpharmacologic interventions such as retransplantation, percutaneous coronary interventions, coronary artery bypass grafting, transmyocardial laser revascularization and heparin-induced/mediated extracorporeal LDL plasmapheresis (HELP). As the use of new assessment tools increases our understanding of this disease, better preventative and treatment strategies are evolving.

Coronary endothelial vasomotor function and vascular remodeling in heart transplant recipients randomized for tacrolimus or cyclosporine immunosuppression

OBJECTIVES

This study aimed to compare changes in coronary endothelial function, systemic endothelin-1 (ET-1) levels, and vascular remodeling in heart transplant recipients randomized to cyclosporin A (CyA) or tacrolimus (Tac) immunosuppression.

BACKGROUND

Functional endothelial abnormalities and intimal thickening are sensitive measures of early cardiac allograft vasculopathy (CAV).

METHODS

The randomized, prospective study was performed in two groups of 22 patients, maintained on Tac or CyA and mycophenolate mofetil immunosuppression, 1 and 12 months after heart transplantation. We investigated epicardial luminal diameter, coronary blood flow velocity, and ET-1 plasma levels at 1 and 12 months after transplantation. Structural coronary alterations were determined using intravascular ultrasound.

RESULTS

Epicardial vasomotor function at baseline and during follow-up was comparable between the groups. Deterioration of microvascular endothelial function during follow-up was significantly enhanced in the CyA versus Tac group (p < 0.05). Circulating ET-1 concentration increased in the CyA group but significantly decreased over time in the Tac group (CyA +17% vs. Tac -25%; p < 0.05). The time-dependent increase in mean intimal area was significantly enhanced in the CyA versus Tac group, whereas the vessel area significantly increased during follow-up in the Tac compared with the CyA group.

CONCLUSIONS

Epicardial endothelial function is comparable between CyA- and Tac-treated patients. Microvascular endothelial function deteriorates more in CyA-treated patients, a finding that correlates with enhanced ET-1 concentration and an increased intimal area during follow-up. The mean vessel area in the Tac group increased over time, indicating positive vascular remodeling. Tac is superior to CyA with respect to microvascular endothelial function, intimal thickening, and vascular remodeling.

Cardiac allograft vasculopathy in pediatric heart transplant recipients

Metabolic parameters for coronary allograft vasculopathy (CAV) have not been well defined in children. CAV (by angiography or autopsy) was studied in 337 heart recipients on a cyclosporine-based steroid-sparing regimen. Freedom from CAV for all was 79% at 10 years. Fifty-nine patients (18%) developed CAV at a mean of 6.5 +/- 3 years post-transplant. First year rejections were significantly higher in CAV, mean 2.3 vs. 1.4, P = 0.003, odds ratio (OR) 1.8. Rejection with hemodynamic compromise beyond 1 year post-transplant was associated with CAV, P < 0.001, OR 8.4. There was no significant correlation among human leukocyte antigen DR (HLA DR) mismatch, pacemaker use or homocysteine levels and the development of CAV. Maximum cholesterol and low density lipoprotein (LDL) levels were not significantly different. Neither diabetes nor hypertension was significant predictors of CAV on multivariate logistic regression analysis. In conclusion, frequent and severe rejection episodes may predict pediatric CAV. Neither glucose intolerance nor lipid abnormalities appeared to alter risk for CAV in this population.

Dendritic cell adhesion is enhanced on endothelial cells preexposed to calcineurin inhibitors

Chronic rejection remains a major complication in solid organ transplantation. Host alloreactive T cells (TC) can be activated by donor dendritic cells (DCs; direct allorecognition) or by recipient DCs (indirect allorecognition). A fundamental aspect of DC function is vascular invasion to present donor antigens to recipient naive TC in secondary lymphoid organs. We investigated the impact of calcineurin inhibitors on DC binding and transmigration to allogeneic human microvascular endothelial cells (ECs) with and without blocking of specific adhesion molecules. Recipient immature DCs were generated by culturing CD14 human peripheral blood monocytes with GM-CSF and IL-4. DC adhesion and transmigration were investigated on allogeneic ECs preincubated with increasing concentrations of cyclosporine and tacrolimus. Experiments were repeated in the presence of blocking antibodies against LFA-1, PECAM-1, VCAM-1, and ICAM-1. Endothelial stimulation with cyclosporine A (100 and 300 ng/mL) and tacrolimus (15 ng/mL) significantly enhanced DC-EC adhesion and transmigration (P<0.01). LFA-1 blockade on DCs significantly reduced cyclosporine- and tacrolimus-induced DC adhesion (P<0.001). VCAM-1 blockade on ECs partially reversed cyclosporine-induced DC adhesion (P<0.001), whereas DC adhesion under tacrolimus exposure was significantly decreased by ICAM-1 (P<0.01) and PECAM-1 (P<0.001) blockade. DC binding and transmigration on allogeneic ECs exposed to calcineurin inhibitors is concentration-dependently increased. Different adhesion molecule patterns on ECs are responsible for enhanced DC invasion under cyclosporine and tacrolimus exposure. We speculate that long-term immunosuppression mediates enhanced invasion of recipient DCs to the donor organ and therefore may aggravate chronic rejection.

Improving outcomes in heart transplantation: the potential of proliferation signal inhibitors

Graft failure and mortality among heart transplant recipients remains higher than in populations receiving renal transplants. A major cause of graft loss is cardiac allograft vasculopathy (CAV), a condition characterized by diffuse thickening of coronary blood vessels. CAV often progresses silently, with major cardiac events (eg, ventricular arrhythmia) being the first presentation. Better diagnosis and monitoring of CAV is now possible with intravascular ultrasonography, a sensitive technique for measuring intimal thickness. To date, immunosuppressants have shown little efficacy for preventing CAV. However, a new class of agents, proliferation signal inhibitors (sirolimus and everolimus), have shown considerable efficacy in this regard and for preventing rejection. In an open-label trial, sirolimus therapy was associated with less intimal and medial proliferation than azathioprine. More robust evidence is available from a larger-scale, double-blind trial involving everolimus. At 12-month follow-up the incidence of CAV was significantly lower in patients receiving everolimus (35.7% and 30.4% for everolimus 1.5 and 3.0 mg/d vs 52.8% for azathioprine; P < .05). Sirolimus and everolimus were also associated with a lower rate of cytomegalovirus infection. As with other immunosuppressants, these agents are associated with adverse events (eg, hyperlipidemia), but they can be managed. Coadministration with calcineurin inhibitors (CNIs) can exacerbate CNI-related nephrotoxicity, but evidence suggests that everolimus administered with reduced-exposure cyclosporine in the maintenance phase preserves renal function without loss of immunosuppressive efficacy. Reduced CNI dosing in de novo patients is also a potential future benefit. Proliferation signal inhibitors have considerable potential for improving outcomes in heart transplantation.

Identification and characterization of Neospora caninum cyclophilin that elicits gamma interferon production

Gamma interferon (IFN-gamma) response is essential to the development of a host protective immunity in response to infections by intracellular parasites. Neosporosis, an infection caused by the intracellular protozoan parasite Neospora caninum, is fatal when there is a complete lack of IFN-gamma in the infected host. However, the mechanism by which IFN-gamma is elicited by the invading parasite is unclear. This study has identified a microbial protein in the N. caninum tachyzoite N. caninum cyclophilin (NcCyP) as a major component of the parasite responsible for the induction of IFN-gamma production by bovine peripheral blood mononuclear cells (PBMC) and antigen-specific CD4(+) T cells. NcCyP has high sequence homology (86%) with Toxoplasma gondii 18-kDa CyP with a calculated molecular mass of 19.4 kDa. NcCyP is a secretory protein with a predicted signal peptide of 17 amino acids. Abundant NcCyP was detected in whole-cell N. caninum tachyzoite lysate antigen (NcAg) and N. caninum tachyzoite culture supernatant. In N. caninum tachyzoite culture supernatant, three NcCyP bands of 19, 22, and 24 kDa were identified. NcAg stimulated high levels of IFN-gamma production by PBMC and CD4(+) T cells. The IFN-gamma-inducing effect of NcAg was blocked by cyclosporine, a specific ligand for CyP, in a dose-dependent manner. Furthermore, cyclosporine abolished IFN-gamma production by PBMC from naïve cows as well as PBMC and CD4(+) T cells from infected/immunized cows. These results indicate that the N. caninum tachyzoite naturally produces a potent IFN-gamma-inducing protein, NcCyP, which may be important for parasite survival as well as host protection.

Cyclosporine A induces vascular fibrosis and heat shock protein expression in rat

The immunosuppressive drug Cyclosporine A (CsA) has been successfully used in several diseases with immunological basis and in transplant patients. However, the therapeutic treatment induces several side effects, which include the development of severe hypertension, renal failure and cardiotoxicity in the majority of the patients. Since the mechanism by which CsA induces hypertension is not well defined, the aim of this study is to evaluate the morphological changes and the expression of heat shock proteins (HSPs) in the thoracic aorta of CsA-treated rats. The study was carried out on 40 male Wistar rats with an average weight of 200-250 g. The animals were divided into four groups. Groups I and II were injected subcutaneously (sc) daily with castor oil for 15 or 30 days and used as control; group III and IV were injected sc daily with CsA (15 mg/Kg/day) for 15 or 30 days. After the end of the treatment, the thoracic aortae were removed and treated for morphological (Sirius Red) and immunohistochemical evaluation (HSP 25, alphaB-crystallin and HSP 47). The results indicate that CsA induces (1) time-dependent vascular damage visible as fibrosis mainly in intima-media tunica of aorta, and (2) a clear increase in HSP expression. In fact, after 30 days of treatment, HSP and alphaB-crystallin are increased in all tunicas, whereas HSP47 only in tunica media and adventitia. These findings could suggest that these proteins are up-regulated after CsA treatment in order to play a defensive role in vascular damage.

AICAR suppresses IL-2 expression through inhibition of GSK-3 phosphorylation and NF-AT activation in Jurkat T cells

We examined the effect of 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR), the dephosphorylated form of AICA ribotide (also termed "ZMP"), an intermediate of purine biosynthesis, on interleukin (IL)-2 production in T cells. AICAR inhibited IL-2 production in Jurkat T cells and peripheral blood lymphocytes activated with PMA plus ionomycin (PMA/Io) or with monoclonal anti-CD3 plus anti-CD28. Pretreatment with 5'-iodotubercidin, an adenosine kinase inhibitor, enhanced AICAR suppression of IL-2 production, suggesting that AICAR, not ZMP, is responsible for IL-2 suppression. We then showed that AICAR inhibited PMA/Io-induced IL-2 mRNA expression and IL-2 promoter activation. AICAR inhibited DNA binding and transcriptional activation of NF-AT and to a lesser extent AP-1, but not NF-kappaB, in PMA/Io-activated Jurkat cells. Finally, we found that AICAR inhibited PMA/Io-induced phosphorylation of GSK-3 but not phosphorylation of ERK1/2, p38, and JNK. These results suggest that AICAR exerts its immunosuppressive effect in activated Jurkat cells by inhibiting GSK-3 phosphorylation and NF-AT activation.

Cardiac transplantation and resistance artery myogenic tone

Transplantation is an effective treatment for end-stage heart disease; however, most grafts eventually fail by progressive cardiac failure. Primarily, failure is ischemic due to the occlusive nature of transplant vascular disease (TVD). Early after transplantation and preceding TVD, alterations in coronary physiology such as reduced vascular myogenic tone occur. Resistance arteries possess an inherent ability to constrict in response to transmural pressure; this constrictive response (myogenic tone) is important in fluid homeostasis. Recent evidence suggests that a decline in myogenic tone leads to deficits in cardiac contractility. Factors that reduce myogenic tone in transplantation include constitutive nitric oxide synthase and inducible nitric oxide synthase catalyzed, NO-mediated vasodilation as well as deficits in arterial contractile function. Reduced myogenic tone in allograft resistance arteries increases coronary blood flow such that hydrostatic pressure surpasses oncotic pressure, causing cardiac interstitial edema. This generalized edema decreases ventricular compliance leading to heart failure during the course of acute immune rejection of the graft. Cyclosporine A treatment reduces immune mediated dysregulation of myogenic tone, resulting in reduced interstitial edema and improved cardiac function. In this review, we discuss aspects of TVD and myogenic tone signaling mechanisms and how aberrations in myogenic regulation of arterial tone contribute to functional changes observed in cardiac transplant.

Mycophenolate mofetil vs. azathioprine is associated with decreased acute rejection, late acute rejection, and risk for cardiovascular death in renal transplant recipients with pre-transplant diabetes

Outcomes specifically in mycophenolate mofetil (MMF)-treated diabetic renal transplant patients have not been previously reported. This study compared acute rejection (AR), late acute rejection (LAR), patient survival [and specifically death from cardiovascular (CV), infectious and malignant causes], incidence of post-transplant malignancies, and graft loss in MMF- or azathioprine (AZA)-treated renal transplant patients with pre-transplant diabetes. Outcomes were compared between MMF- (n = 14 144) and AZA- (n = 3001) treated diabetic patients using the Scientific Registry of Transplant Recipients data on all U.S. adult renal transplants performed between 1995 and 2002. Statistical analyses included Kaplan-Meier survival analysis, Cox multivariable regression and chi-square tests. MMF patients had less AR compared with AZA-treated patients (23.5% vs. 28.3%, p < 0.001) and less risk for LAR over 4 yr [hazard ratio (HR): 0.64, 95% CI 0.44, 0.92; p = 0.02]. While time to any-cause death did not differ between the groups, MMF treatment was associated with a 20% decreased risk of CV death (HR: 0.80, 95% CI 0.67, 0.97; p = 0.020) compared with AZA treatment. MMF patients also had a lower incidence of malignancies than AZA patients (2.2% vs. 3.7%, p < 0.001). These results suggest treatment with MMF compared with treatment with AZA in diabetic transplant patients is associated with less AR, less risk of LAR, a decreased risk of CV death, and a lower incidence of malignancies.

New-onset diabetes after transplantation

For many years new-onset diabetes after transplantation has been recognized as a complication of solid-organ transplantation, although its importance has been greatly underestimated. Studies have shown that the cumulative incidence of this condition in heart transplant recipients may reach 32% at 5 years, similar to that reported in kidney and liver transplant patients. Several factors predispose to increased risk for developing new-onset diabetes after transplantation, including age, ethnicity, family history of diabetes, obesity and immunosuppressive therapy. Corticosteroids are associated with the greatest risk of developing the condition. Tacrolimus is more diabetogenic than cyclosporine in kidney and liver transplant patients, but there are few data reporting the effects of these agents in heart transplant patients. In kidney transplant patients, diabetes is known to be a significant risk factor for cardiovascular disease post-transplant. Although this has yet to be demonstrated clearly in heart transplant patients, evidence suggests that new-onset diabetes after transplantation may play a role in the development of cardiac allograft vasculopathy (CAV). Because CAV is the major limitation to long-term survival in this population, it is clear that efforts should be made to reduce the risk of diabetes and treat this condition appropriately. Management of transplant recipients with new-onset diabetes after transplantation has been assisted by the recent publication of International Consensus Guidelines. The guidelines were developed to establish a standard definition and describe risk factors for new-onset diabetes after transplantation. Use of these guidelines will help to prospectively identify those at risk of developing new-onset diabetes after transplantation so that therapeutic strategies can be individualized early in the treatment regimen. These management approaches should help to lower the risk of new-onset diabetes after heart transplantation and reduce the possible long-term consequences of the condition.

Cardiac allograft vasculopathy after heart transplantation: risk factors and management

Cardiovascular disease post-transplant, particularly ischemic heart disease, is a significant problem for all transplant recipients. The major risk factors-smoking, obesity, diabetes, dyslipidemia and hypertension-are often more prevalent in heart transplant populations than in the general population. One of the main risk factors influencing graft loss and patient survival is cardiac allograft vasculopathy (CAV). Because CAV affects between 30% and 60% of cardiac transplant recipients within 5 years of surgery, prevention is a key focus for cardiac transplant teams today. CAV is caused by both immunologic mechanisms (e.g., acute rejection and anti-HLA antibodies) and non-immunologic mechanisms relating to the transplant itself or the recipient (e.g., donor age, hypertension, hyperlipidemia and pre-existing diabetes) or to the side effects often associated with immunosuppression with calcineurin inhibitors or corticosteroids (e.g., cytomegalovirus infection, nephrotoxicity and new-onset diabetes after transplantation). The calcineurin inhibitors, cyclosporine and tacrolimus, effectively prevent acute rejection, but do not prevent the development of CAV. CAV prevention will require a combined approach of new adjunct immunosuppressant agents (e.g., the proliferation signal inhibitors) and reduction in cardiovascular risk. Hypertension, hyperlipidemia and diabetes are also associated with the immunosuppression required to prevent organ rejection. Some studies have shown that hypertension is present more frequently in cyclosporine-treated patients than in tacrolimus-treated patients and that tacrolimus may be associated with a more favorable lipid profile. On the other hand, tacrolimus may be more diabetogenic than cyclosporine with current data suggesting a trend but no statistically significant supporting evidence. New-onset diabetes after transplantation is at times difficult to manage and may be an important determinant along with hypertension and hyperlipidemia of ischemic heart disease, cerebrovascular disease and peripheral vascular disease. The choice of calcineurin inhibitor for an immunosuppressive regimen in heart transplantation should consider the associated relative cardiovascular risks.

Calcineurin inhibitors in heart transplantation

The use of calcineurin inhibitors (CNIs; cyclosporine and tacrolimus) has dramatically increased medium-term life expectancy after heart transplantation but has had only limited impact on long-term outcomes for heart transplant recipients. The original oil-based formulation of cyclosporine has been superceded by a microemulsion formulation (Neoral), which has more predictable pharmacokinetics and allows more precise dose-tailoring. Cyclosporine microemulsion and tacrolimus (Prograf) have a similar efficacy in the prevention of acute rejection of heart transplants, but their use is accompanied by nephrotoxicity and by cardiovascular side effects. The efficacy of immunosuppression can be improved by adjunctive therapy, such as azathioprine, mycophenolate mofetil (MMF; Cellcept), corticosteroids, and induction therapy. One of the most important predictors of patient mortality at >5 years after heart transplantation is cardiac allograft vasculopathy (CAV)/late graft failure, which accounts for 31% of deaths. Neither cyclosporine nor tacrolimus have been shown to prevent the development of CAV. In terms of efficacy, MMF provides a modest advantage over azathioprine in preventing CAV, and the combination of cyclosporine plus MMF results in significantly lower mortality than cyclosporine plus azathioprine. Overall, CNIs have multiple cardiovascular side effects, such as hypertension, hyperlipidemia and new-onset diabetes after transplantation, although cyclosporine and tacrolimus have somewhat different cardiovascular side-effect profiles. The challenge in choosing the best immunosuppressive regimen is to balance efficacy and safety to optimize graft and patient survival over the course of many decades. Because cyclosporine and tacrolimus have similar efficacy against acute rejection the choice of CNI for heart transplant recipients should be based on the relative risk of cardiovascular and renal side effects.