Beneficial effects of conversion from cyclosporine to azathioprine on fibrinolysis in renal transplant recipients

Statin use and incident cardiovascular events in renal transplant recipients

BACKGROUND

Statins achieve potent LDL lowering in the general population leading to a significant cardiovascular (CV) risk reduction. In renal transplant recipients (RTR) statins are included in treatment guidelines, however, conclusive evidence of improved cardiovascular outcomes has not been uniformly provided and concerns have been raised about simultaneous use of statins and the immunosuppressant cyclosporine. This study aimed to elucidate the effect of statins on a compound CV endpoint, comprised of ischaemic CV events and CV mortality in RTR, with subgroup analysis focussing on cyclosporine users.

METHOD

622 included RTR (follow-up 5.4 years) were matched based on propensity scores and dichotomized by statin use. Survival analysis was conducted.

RESULTS

Cox regression showed that statin use was not significantly associated with the compound CV endpoint in a fully adjusted model (HR = 0.81, 95% CI = 0.53-1.24, P = .33). Subgroup analyses in RTR using cyclosporine revealed a strong positive association of statin use with the CV compound outcome in a fully adjusted model (HR = 6.60, 95% CI 1.75-24.9, P = .005). Furthermore, statin use was positively correlated with cyclosporine trough levels (correlation coefficient 0.11, P = .04).

CONCLUSION

In conclusion, statin use does not significantly decrease incident CV events in an overall RTR cohort, but is independently associated with CV-specific mortality and events in cyclosporine using RTR, possibly due to a bilateral pharmacological interaction.

Inflammatory bowel disease and thromboembolic events

Thromboembolism (TE) is an extraintestinal manifestation (EIM) of inflammatory bowel disease (IBD). According to previous pathological reports, the incidence of IBD complicated with TE is as high as 41%. However, this EIM is often overlooked. This review summarizes the results of the relevant clinical studies to date, analyzes the potential prothrombotic risk of IBD drug therapy, and discusses the current status on the treatment and prevention of TE, with an aim to provide a comprehensive reference for clinical work.

Reducing Adverse Effects of Immunosuppressive Agents in Kidney Transplant Recipients

Success in solid organ transplantation with minimal complications can now be achieved for most patients, and a remarkable rate of graft and patient survival can also be expected. However, the potential for adverse events and comorbid conditions increases with longer graft survival. Although the immunosuppressive regimen is central to the outcome of the transplant recipient and directly impacts the survival of the graft, chronic use of immunosuppressive agents is associated with metabolic disturbances such as hypertension, hyperlipidemia, loss of bone density, nephrotoxicity, and diabetes, which may contribute to other comorbid conditions. In addition, changes in appearance, gingival hyperplasia, hirsutism, alopecia, and weight gain disrupt quality of life and may lead to noncompliance with the immunosuppressive regimen. New immunosuppressive medications, including mycophenolate mofetil, sirolimus, basiliximab, and daclizumab, have allowed for experimentation with new regimens designed to reduce or allow discontinuation of corticosteroids and calcineurin inhibitors. This review highlights the impact and cost of immunosuppressive side effects and the potential for new immunosuppressive regimens to reduce this substantial clinical burden in transplantation.

The influence of corticosteroids on hemostasis in healthy subjects

BACKGROUND

Corticosteroids have been associated with an increased risk of venous thromboembolism in patients treated for inflammatory diseases. It is unclear whether the thrombotic risk is induced by the inflammation of the underlying inflammatory diseases or whether corticosteroids are prothrombotic as well. Considering the widespread use of corticosteroids in clinical practise, it is critical to know whether corticosteroids enhance coagulation.

OBJECTIVE

To investigate whether a 10-day prednisolone burst therapy activates hemostasis in healthy individuals.

METHODS

Healthy subjects received either 0.5 mg kg(-1) day(-1) of oral prednisolone or placebo. Venous blood was collected at baseline, day 1 and day 10 and tested for thrombin-antithrombin complexes (TATc), D-dimer, plasmin-alpha2-antiplasmin complexes (PAPc), plasminogen-activator inhibitor type-1 (PAI-1), von Willebrand factor (VWF) and thrombin generation (peak thrombin, velocity index and endogenous thrombin potential [ETP]).

RESULTS

Fifteen subjects received prednisolone and 16 placebo (median age 29 vs. 22 years, female subjects 33% vs. 56%, respectively). Peak thrombin and velocity index were higher in the placebo group at baseline. After 10 days of treatment, peak thrombin, velocity index, PAI-1 and VWF increased in the oral prednisolone group as compared with the placebo group (15.8 [SD 16.3] vs. -0.1 [SD 16.1], 41.2 [SD 41.3] vs. -2.3 [SD 42.7], 18.0 [IQR 8.0-37.0] vs. 0.5 [IQR -18.5-13.0], 4.0 [IQR -1.0-12.0] vs. 0.0 [IQR -2.5-1.5], respectively). No changes were observed for TATc, ETP, PAPc and D-dimer.

CONCLUSIONS

Oral prednisolone induces a procoagulant state in healthy subjects, suggesting that corticosteroid treatment may increase the thromboembolic risk in patients with inflammatory diseases.

Harmful effects of the azathioprine metabolite 6-mercaptopurine in vascular cells: induction of mineralization

Vascular mineralization contributes to the high cardiovascular morbidity and mortality in patients who suffer from chronic kidney disease and in individuals who have undergone solid organ transplantation. The immunosuppressive regimen used to treat these patients appears to have an impact on vascular alterations. The effect of 6-mercaptopurine (6-MP) on vascular calcification has not yet been determined. This study investigates the effect of 6-MP on vascular mineralization by the induction of trans-differentiation of rat vascular smooth muscle cells in vitro. 6-MP not only induces the expression of osteo-chondrocyte-like transcription factors and proteins but also activates alkaline phosphatase enzyme activity and produces calcium deposition in in vitro and ex vivo models. These processes are dependent on 6-MP-induced production of reactive oxygen species, intracellular activation of mitogen-activated kinases and phosphorylation of the transcription factor Cbfa1. Furthermore, the metabolic products of 6-MP, 6-thioguanine nucleotides and 6-methyl-thio-inosine monophosphate have major impacts on cellular calcification. These data provide evidence for a possible harmful effect of the immunosuppressive drug 6-MP in vascular diseases, such as arteriosclerosis.

Effect of immunosuppressive agents on long-term survival of renal transplant recipients: focus on the cardiovascular risk

In the control of acute rejection, attention is being focused more and more on the long-term adverse effects of the immunosuppressive agents used. Since cardiovascular disease is the main cause of death in renal transplant recipients, optimal control of cardiovascular risk factors is essential in the long-term management of these patients. Unfortunately, several commonly used immunosuppressive drugs interfere with the cardiovascular system. In this review, the cardiovascular adverse effects of the immunosuppressive agents currently used for maintenance immunosuppression are thoroughly discussed. Optimising immunosuppression means finding a balance between efficacy and safety. Corticosteroids induce endothelial dysfunction, hypertension, hyperlipidaemia and diabetes mellitus, and impair fibrinolysis. The use of corticosteroids in transplant recipients is undesirable, not only because of their cardiovascular effects, but also because they induce such adverse effects as osteoporosis, obesity, and atrophy of the skin and vessel wall. Calcineurin inhibitors are the most powerful agents for maintenance immunosuppression. The calcineurin inhibitor ciclosporin (cyclosporine) not only induces these same adverse effects as corticosteroids but is also nephrotoxic. Tacrolimus has a more favourable cardiovascular risk profile than ciclosporin and is also less nephrotoxic. It has little or no effect on blood pressure and serum lipids; however, its diabetogenic effect is more prominent in the period immediately following transplantation, although at maintenance dosages, the diabetogenic effect appears to be comparable to that of ciclosporin. The diabetogenic effect of tacrolimus can be managed by reducing the dose of tacrolimus and early corticosteroid withdrawal. The effect of tacrolimus on endothelial function has not been completely elucidated. The proliferation inhibitors azathioprine and mycophenolate mofetil (MMF) have little effect on the cardiovascular system. Yet, indirectly, by inducing anaemia, they may lead to left ventricular hypertrophy. MMF is an attractive alternative to azathioprine because of its higher potency and possibly lower risk of malignancies. Sirolimus also induces anaemia, but may be promising because of its antiproliferative features. Whether the hyperlipidaemia induced by sirolimus counteracts its beneficial effects is, as yet, unknown. It may be combined with MMF, however, initial attempts resulted in severe mouth ulcers.

Plasminogen activators and plasminogen activator inhibitors in gingival crevicular fluid of cyclosporin A-treated patients

BACKGROUND

The plasminogen activator (PA) system plays many roles in the inflammatory process and tissue remodelling and repair and is considered to play a significant role in periodontal tissue destruction and healing. The aim of this study was to evaluate the role of the PA system in cyclosporin A (CsA)-induced gingival overgrowth in renal transplant patients.

METHODS

Eighteen renal transplant patients exhibiting moderate to severe CsA-induced gingival overgrowth, 10 other renal transplant patients receiving CsA therapy but showing no sign of CsA-induced gingival overgrowth (CsA-H), 16 chronic gingivitis patients (CG) and 16 systemically and periodontally healthy control subjects (H) were included in the study. Gingival crevicular fluid (GCF) samples were obtained from four randomly selected sites in each subject with the exception of the CsA-induced gingival overgrowth group, where four GCF samples were harvested from sites with severe overgrowth (CsA GO+) and from four sites without any gingival overgrowth (CsA GO-). The GCF levels of albumin, tissue-type plasminogen activator (t-PA), urokinase-type plasminogen activator (u-PA), plasminogen activator inhibitor 1 (PAI-1) and plasminogen activator inhibitor 2 (PAI-2) were analysed by enzyme-linked immunosorbent assay. The results were tested for statistical differences.

RESULTS

In CsA GO+ sites t-PA levels were significantly elevated in comparison with gingivitis and healthy sites, while PAI-2 levels in these sites showed statistically significant differences only with CsA-H and gingivitis sites (p<0.05). The levels of t-PA and PAI-2 were significantly higher in CsA GO- sites compared with those of CsA-H, gingivitis and healthy sites (p<0.05). The levels of u-PA and PAI-1 failed to show significant differences between the study groups.

CONCLUSIONS

The findings of the present study indicate alterations in GCF t-PA and PAI-2 levels in CsA-induced gingival overgrowth and might suggest involvement of the plasminogen activating system in the pathogenesis of this side-effect of CsA therapy. However, to what extent these molecules contribute to the pathogenesis of CsA-induced gingival overgrowth remains to be determined.

Impact of kidney transplantation on the progression of cardiovascular disease

Kidney transplantation, of all the treatment modalities for end-stage renal disease, affords the greatest potential for prolonged survival and improved quality of life. Great strides in immunosuppressant therapy have improved graft survival and forced clinicians to consider other health-care needs of kidney transplant recipients. Chief among these needs is the prevention and treatment of cardiovascular disease. Cardiovascular disease is the most common cause of death among patients with a working renal allograft. Because therapies for primary and secondary prevention are successful in the general population, transplant clinicians are increasingly focused on preventing or limiting the progression of cardiovascular disease. Initiation of aggressive management of conventional atherosclerotic risk factors and uremia-related risk factors, ideally during the early stages of chronic kidney disease (CKD) or after kidney transplantation, and efforts to delay the progression of kidney disease will hopefully reduce the cardiovascular burden in transplant recipients.

Some aspects of hemostasis in kidney transplant recipients maintained on cyclosporine, azathioprine, and prednisone in comparison to patients treated with cyclosporine and prednisone

Cyclosporine (CyA) has been implicated to increase cardiovascular morbidity and mortality after renal transplantation. Impairment of the fibrinolytic system is one factor involved in the development of thrombotic complications. The aim of this study was to compare hematological and hemostatic parameters among patients on CyA, azathioprine, and prednisone (n = 31) versus CyA and steroids (n = 14). Using commercially available kits we evaluated thrombin activity as thrombin-antithrombin complexes (TAT), prothrombin fragments (1 + 2), thrombin activatable fibrinolysis inhibitor-(TAFI), TAFI activator, thrombomodulin (TM)-a marker for endothelial cell injury,-plasmin generation (plasmin-antiplasmin complex PAP), a glycoprotein linking coagulation and fibrinolysis. We observed that patients not treated with azathioprine displayed longer prothrombin times and activated partial thromboplastin times; higher fibrinogen, platelet counts and fibrinolytic activity index (FAI); shorter euglobulin clot lysis time; as well as lower thrombin generation markers namely, prothrombin fragments 1 + 2 and thrombin-antithrombin complexes. Although patients in the non-AZA group tended to have been engrafted for a longer time (P =.086), the groups did not differ with regard to age, BMI, erythrocyte count, hematocrit, leukocyte count, creatinine clearance, alanine and asparagine aminotransferase activities mean arterial blood pressure, fibrinogen, TAFI, thrombomodulin, or plasmin-antiplasmin complexes. These findings suggest that kidney transplant recipients on triple therapy are at greater risk of cardiovascular disease than those without azathioprine treatment, despite the lower fibrinolytic activity.

Improved cardiovascular risk profile and renal function in renal transplant patients after randomized conversion from cyclosporine to tacrolimus

Cyclosporine is considered to contribute to the high cardiovascular morbidity and mortality in patients after renal transplantation. Tacrolimus may be more favorable in this respect, but controlled data are scarce. In this prospective randomized study in 124 stable renal transplant patients, the effects of conversion from cyclosporine to tacrolimus on cardiovascular risk factors and renal function were investigated. Follow-up was 6 mo. Statistical analysis was performed by ANOVA for repeated measurements. The serum creatinine level decreased from 137 +/- 30 micromol/L to 131 +/- 29 micromol/L (P < 0.01). Three months after conversion from cyclosporine to tacrolimus, mean BP significantly decreased from 104 +/- 13 to 99 +/- 12 mmHg (P < 0.001). Serum LDL cholesterol decreased from 3.48 +/- 0.80 to 3.11 +/- 0.74 mmol/L (P < 0.001,) and serum apolipoprotein B decreased from 1018 +/- 189 to 935 +/- 174 mg/L (P < 0.001). Serum triglycerides decreased from 2.11 +/- 1.12 to 1.72 +/- 0.94 mmol/L (P < 0.001). In addition, both rate and extent of LDL oxidation were reduced. The fibrinogen level decreased from 3638 +/- 857 to 3417 +/- 751 mg/L (P < 0.05). Plasma homocysteine concentration did not change. Three months after conversion, plasma fasting glucose level temporarily increased from 5.4 +/- 1.3 mmol/L to 5.8 +/- 1.9 mmol/L (P < 0.05). Conversion to tacrolimus resulted in a significant reduction of the Framingham risk score. In conclusion, conversion from cyclosporine to tacrolimus in stable renal transplant patients has a beneficial effect on renal function, BP, serum concentration and atherogenic properties of serum lipids, and fibrinogen.

Plasma fibrinolytic capacity in renal transplant recipients: effect of steroid-free immunosuppression therapy

BACKGROUND

Cardiovascular disease is the most common cause of death among renal transplant recipients (RTRs). Impaired fibrinolytic capacity caused by an increase in plasminogen activator inhibitor type 1 (PAI-1) levels is involved in the onset of atherosclerosis and thrombotic complications. Long-term steroid treatment may induce arterial hypertension and metabolic and prothrombotic changes (including up-regulation of PAI-1 synthesis), which increase the cardiovascular risk. We evaluated plasma fibrinolytic behavior in two groups of RTRs treated with different immunosuppressive regimens.

METHODS

Twenty-seven RTRs were randomized to receive long-term (17 patients) or perioperative short-term (10 patients) steroids in addition to immunosuppression with cyclosporine A plus everolimus (Certican; Novartis, Basel, Switzerland) (7 patients) or FK506 plus mycophenolate mofetil (20 patients). In each patient, fibrinolytic capacity was studied with the 20-min venous occlusion test 1 and 6 months after transplantation. The following were assayed: euglobulin lysis time, tissue-type plasminogen activator antigen, and PAI-1 antigen and activity.

RESULTS

One month after transplantation, a severe impairment of fibrinolytic capacity, mainly caused by an increase in PAI-1 antigen and activity levels, was seen in patients with and without steroid treatment. Six months after transplantation, an improvement in fibrinolytic potential as the result of a decrease in PAI-1 levels was observed only in patients without steroid therapy. None of the steroid-treated patients demonstrated PAI-1 values correlating with body mass index, blood pressure, and metabolic parameters, thus confirming the effect of exogenous factors on PAI-1 expression. Moreover, all patients revealed a slight impairment of stimulated endothelial tissue-type plasminogen activator release, regardless of any steroid treatment, which was probably attributable to calcineurin inhibitor-induced endothelial dysfunction.

CONCLUSIONS

Our study suggests that steroid-free immunosuppression is associated with a better fibrinolytic capacity in RTRs. This finding may contribute toward reducing the risk of cardiovascular events.

Association of plasminogen activator inhibitor-1 genotype with avascular osteonecrosis in steroid-treated renal allograft recipients

BACKGROUND

The mechanism of avascular osteonecrosis (AVN) is controversial. Besides an increased bone marrow pressure with reduced blood supply, an enhanced coagulation has been considered. We hypothesize that a genetic variant of the plasminogen activator inhibitor-1 (PAI-1) determines the risk of AVN in glucocorticoid-treated patients.

METHODS

Genotyping for the 4G/5G PAI-1 polymorphism was performed in 228 glucocorticoid-treated renal transplant patients. AVN of the hip was present in 26 patients. Magnetic resonance imaging (MRI) of the hips was obtained in 81 of the remaining renal transplant patients without clinical symptoms of AVN.

RESULTS

The presence of the homozygous 4G/4G PAI-1 genotype was higher in patients with AVN (60.3%) as compared with patients without either clinical (20.6%, P<0.007) or radiological signs of AVN (17.3%, P<0.002). The prevalence of AVN by genotype was 1.8% with the 5G/5G, 7.7% with the 5G/4G, and 30.3% with the 4G/4G alleles (P<0.001 vs. 5G/4G and 5G/5G). The prevalence of AVN increased with increasing body mass index (BMI) (P=0.04). The prevalence of AVN by genotype in subjects with persistent hyperparathyroidism was 4.2% with the 5G/5G, 15.2% with the 5G/4G, and 55.5% with the 4G/4G alleles (P<0.003 vs. 5G/4G and P<0.001 vs. 5G/5G).

CONCLUSIONS

Hypofibrinolysis conferred by the 4G/4G PAI-1 gene variant is a major predisposing factor for AVN in renal transplant patients. The risk is particularly high in obese subjects or patients with persistent hyperparathyroidism. A prospective intervention study of early anticoagulation after renal transplantation is needed to assess whether glucocorticoid-associated AVN can be prevented.

Cardiovascular toxicities of immunosuppressive agents

Cardiovascular disease is one of the major causes of morbidity and mortality following solid organ transplantation. Many of the current immunosuppressive drugs are associated with an increase of one or more risk factors for the development of atherosclerosis. This review compares the mechanism by which individual immunosuppressive agents may impact on these risk factors and the differential contribution of cyclosporine, tacrolimus, mycophenolate, azathioprine, and Rapamycin to these individual risk factors. Attention to the potential cardiovascular toxicities of individual immunosuppressive agents may help design strategies for maintenance of immunosuppression tailored to individual patients.

Cardiovascular disease after renal transplantation

Cardiovascular disease is a major hazard limiting the life expectancy of renal transplant recipients and the most frequent cause of late allograft loss. Patients with renal disease have usually been exposed for both traditional, and for them unique, risk factors over a prolonged period of time and may carry the burden of advanced atherosclerotic disease already at the time of transplantation. The observed survival benefit of transplantation is probably from elimination of the numerous uremia-related risk factors. However, immunosuppressive therapy and the chronic inflammatory state, together with genetic susceptibility and not infrequently impaired renal function, may bring about new potentially atherogenic conditions. Metabolic risk factors may jeopardize both patient and graft survival. Several observational studies provide evidence for the negative impact of preexisting metabolic abnormalities on long-term outcomes. Identification of modifiable cardiovascular risk factors may enable risk reduction also in renal transplant recipients. Results of ongoing intervention trials are awaited. The observed improvement of patient survival after renal transplantation during the past decade may reflect the increasing awareness and more optimal care of patients throughout the course of renal disease.

Defining the risk of elective cyclosporine withdrawal in stable kidney transplant recipients

Although it is known that elective cyclosporine (CsA) withdrawal increases the risk for acute rejection, few studies have been large enough to identify risk factors for acute rejection after CsA withdrawal. We examined risk factors for acute rejection in 464 kidney transplant recipients who underwent elective CsA withdrawal. The incidence of acute rejection within 6 months of CsA withdrawal was 20/141 (14.2%) in the period January 1986 to May 1989, but only 14/323 (4.5%) since May 1989 (p = 0.0002). Among those transplanted since May 1989, the incidence was 5/20 (25%) for those with both 2 HLA-B and 2 HLA-DR mismatches, compared with only 9/298 (3.0%) for those with fewer mismatches (p < 0.0001). In Cox proportional hazards analysis, risk factors for acute rejection within 6 months, or at any time after elective CsA withdrawal, were date of transplant January 1986 to May 1989 (compared with more recently May 1989 to March 1999), younger age, obesity, as well as B and DR mismatches. Recipient race (83% were white), acute rejection during the first year before withdrawal (31%), mycophenolate mofetil (17%), and other variables failed to predict postwithdrawal acute rejection. We concluded that avoiding CsA withdrawal in the relatively small number of recipients with both 2 HLA-B and 2 HLA-DR mismatches could further reduce our already low incidence of acute rejection following elective CsA withdrawal.

Reducing adverse effects of immunosuppressive agents in kidney transplant recipients

Success in solid organ transplantation with minimal complications can now be achieved for most patients, and a remarkable rate of graft and patient survival can also be expected. However, the potential for adverse events and comorbid conditions increases with longer graft survival. Although the immunosuppressive regimen is central to the outcome of the transplant recipient and directly impacts the survival of the graft, chronic use of immunosuppressive agents is associated with metabolic disturbances such as hypertension, hyperlipidemia, loss of bone density, nephrotoxicity, and diabetes, which may contribute to other comorbid conditions. In addition, changes in appearance, gingival hyperplasia, hirsutism, alopecia, and weight gain disrupt quality of life and may lead to noncompliance with the immunosuppressive regimen. New immunosuppressive medications, including mycophenolate mofetil, sirolimus, basiliximab, and daclizumab, have allowed for experimentation with new regimens designed to reduce or allow discontinuation of corticosteroids and calcineurin inhibitors. This review highlights the impact and cost of immunosuppressive side effects and the potential for new immunosuppressive regimens to reduce this substantial clinical burden in transplantation.

A possible role of thrombin-activatable fibrinolysis inhibitor in disturbances of fibrinolytic system in renal transplant recipients

BACKGROUND

Cardiovascular disease (CVD) is a major cause of death in renal transplant recipients (RTR). Suppression of fibrinolysis plays a role in the progression of atherosclerosis. Accelerated progression of atherosclerosis and fibrinolytic system suppression has been observed in RTR. Despite many years of intensive research, the reason for impaired fibrinolysis in this patient population is not fully understood. Thrombin-activatable fibrinolysis inhibitor (TAFI) is a recently discovered glycoprotein combining coagulation and fibrinolysis. This study was conducted to evaluate concentrations of TAFI, markers of thrombin generation, endothelial injury, and some standard laboratory parameters in RTR receiving triple immunosuppressive drug regimen.

METHODS

The study was performed in 29 stable, non-diabetic kidney transplant recipients treated with cyclosporin A, azathioprine, and prednisone and in 18 age- and sex-matched healthy volunteers. Soluble thrombomodulin (sTM), prothrombin fragments F1+2 (F1+2), thrombin--antithrombin complexes (TAT), plasmin--antiplasmin complexes (PAP), and TAFI were measured with commercially available kits.

RESULTS

The RTR group had significantly higher plasma levels of TAT, F1+2, sTM and TAFI than the healthy volunteers. There were no differences in PAP concentrations between the two groups. Plasma sTM correlated inversely with creatinine clearance, body mass index, haemoglobin, and albumin. Plasma TAT level was positively associated with total cholesterol. TAFI antigen influenced negatively PAP antigen concentration.

CONCLUSIONS

On the basis of our research, we concluded that elevated circulating TAFI antigen might be a new link in the pathogenesis of impaired fibrinolysis in RTR, and thus atherosclerosis progression. In the patient group there is also evidence of endothelial injury, followed by secondary activation of the coagulation cascade. Hypercholesterolaemia in RTR is associated with enhanced thrombin activity.

Weight gain and cardiovascular risk after organ transplantation

Organ transplantation has become a common and effective approach to the management of patients with organ failure. The improvement in long-term survival has resulted in the emergence of cardiovascular disease as the primary cause of death in renal transplant patients and a significant complication in other organ recipients. A number of factors explain this trend, including a high incidence of hypertension, posttransplant diabetes, hyperlipidemia, and obesity-risk factors that are mediated by direct effects of immunosuppressive medications. Weight gain posttransplant affects approximately 50% of patients and represents a significant problem because of the potential synergism between obesity and immunosuppressive medication-induced effects on cardiovascular disease risk factor development. This review discusses the incidence and implications of cardiovascular disease risk factors in organ transplant recipients, strategies for clinical management, and future research directions.

Production of plasminogen activator inhibitor-1 by human mast cells and its possible role in asthma

The plasminogen activator inhibitor type 1 (PAI-1) has an essential role in tissue remodeling. The PAI-1 gene was induced by a combination of phorbol ester and calcium ionophore at the highest level among the inducible human mast cell genes that we have analyzed on a DNA microarray. PAI-1 was secreted by both a human mast cell line (HMC)-1 and primary cultured human mast cells upon stimulation, whereas PAI-1 was undetectable in either group of unstimulated cells. The secretion of PAI-1 was due to de novo synthesis of PAI-1 rather than secretion of preformed PAI-1. The functional significance of PAI-1 secretion was demonstrated by complete inhibition of tissue-type plasminogen activator activity with supernatants of stimulated HMC-1 cells. Furthermore, we were able to regulate PAI-1 gene expression in HMC-1 cells by known therapeutic agents. High-dose (1 microM) dexamethasone induced PAI-1 mRNA expression. Cyclosporin down-regulated the expression of the PAI-1 gene. Cycloheximide abrogated PAI-1 mRNA expression, suggesting that transcription of the PAI-1 gene requires de novo synthesis of early gene products, including transcription factors. Finally, we demonstrated PAI-1 in lung mast cells from a patient with asthmatic attack by double-immunofluorescence study. This is the first report demonstrating that activated human mast cells release a striking amount of functionally active PAI-1. These results suggest that PAI-1 could play an important role in airway remodeling of asthma, and inhibition of PAI-1 activity could represent a novel therapeutic approach in the management of airway remodeling.

Improved fibrinolytic capacity after withdrawal of steroid immunosuppression in renal transplant recipients

BACKGROUND

Long-term steroid immunosuppression has been associated with the prothrombotic state observed in renal transplant (RT) patients, in whom both hypercoagulability due to an increase of von Willebrand factor/factor VIII complex, and impaired fibrinolysis due to PAI-1 excess have been demonstrated. Our aim was to investigate the effect of steroid withdrawal on fibrinolytic capacity in a group of RT patients.

METHODS

The fibrinolytic study was performed in 28 RT patients under stable immunosuppression therapy with cyclosporine, azathioprine, and methylprednisolone; only 12 of these patients could repeat the study 6 months after steroid withdrawal. Euglobulin lysis time (ELT), tissue plasminogen activator activity (t-PA:act) and antigen (t-PA:Ag), PAI-1 activity (PAI-1:act), and antigen (PAI-1:Ag) were assayed on blood samples drawn before and 20 min after the venous occlusion test (VO).

RESULTS

An hypofibrinolytic state due to a significant increase in PAI-1 levels was confirmed in RT patients receiving triple immunosuppression therapy. RT patient who stayed off steroids showed a significant shortening of ELT both before (P=0.01) and 20' after VO (P=0.005) at the 6-month control. Moreover, after steroid withdrawal, PAI-1:Ag levels decreased significantly (P=0.002) and normalized; in a similar manner PAI-1:act levels also showed a significant decrease both before (P=0.001), and after VO (P=0.0001). The prevalence of RT patients with impaired fibrinolytic capacity was as high as 83.3% during steroid treatment, and dropped to 16.7% after steroid withdrawal.

CONCLUSIONS

Our findings confirm that steroid withdrawal may normalize impaired fibrinolytic capacity in RT patients; this improvement may further contribute to reduce the thrombotic risk associated with renal transplantation.