sirolimus and Thromboembolism

Little is known about the risk of venous thrombosis following kidney transplant. To determine this we estimated the risk of thromboembolic events (TEs) in a cohort of consecutive patients who underwent kidney transplantation at a single tertiary care center over an 11-year period and calculated standardized incidence ratios (SIRs) for a first TE in kidney transplant recipients compared with the general population. We then performed a nested case-control study and compared patients with and without TEs to identify risk factors for thrombosis. Among 913 kidney transplant recipients (KTRs), 68 patients developed these events. The SIR for TEs in KTRs compared with the general population was 7.9 over the duration of follow-up. The risk was particularly higher in the first post-transplant year (SIR 26.1) but remained elevated afterward (SIR 5.2). Hospitalization, use of sirolimus, low hemoglobin level, and use of renin-angiotensin system inhibitors were independently associated with these events. When cases of TEs that occurred during hospitalization were excluded, the risk of these events remained elevated. The risk of TEs in KTRs was eightfold higher than in the general population but not fully explained by the increased risk associated with hospitalization. Our results underscore the important risk of thrombosis in patients who received a kidney transplant, making vigilance mandatory especially during hospitalization.

Topics: Adult; Aged; Female; Humans; Immunosuppressive Agents; Kidney Transplantation; Male; Middle Aged; Patient Readmission; Quebec; Retrospective Studies; Risk Assessment; Risk Factors; Sirolimus; Tertiary Care Centers; Thromboembolism; Time Factors; Treatment Outcome; Young Adult

Pulmonary vascular remodeling occurs in patients with chronic thromboembolic pulmonary hypertension (CTEPH). One factor contributing to this vascular wall thickening is the proliferation of pulmonary artery smooth muscle cells (PASMC). Store-operated Ca(2+) entry (SOCE) and cytosolic free Ca(2+) concentration ([Ca(2+)](cyt)) in PASMC are known to be important in cell proliferation and vascular remodeling in pulmonary hypertension. Rapamycin is widely known for its antiproliferative effects in injured coronary arteries. Although several reports have suggested favorable effects of rapamycin in animal models of pulmonary hypertension, no reports have been published to date in human tissues. Here we report that rapamycin has an inhibitory effect on SOCE and an antiproliferative effect on PASMC derived from endarterectomized tissues of CTEPH patients. Cells were isolated from endarterectomized tissues obtained from patients undergoing pulmonary thromboendarterectomy (PTE). Immunohistochemical analysis indicated high deposition of platelet-derived growth factor (PDGF) in tissue sections from PTE tissues and increased PDGF receptor expression. PDGF transiently phosphorylated Akt, mammalian target of rapamycin (mTOR), and p70S6 kinase in CTEPH cells from CTEPH patients. Acute treatment (30 min) with rapamycin (10 nM) slightly increased cyclopiazonic acid (10 microM)-induced Ca(2+) mobilization and significantly reduced SOCE. Chronic treatment (24 h) with rapamycin reduced Ca(2+) mobilization and markedly inhibited SOCE. The inhibitory effects of rapamycin on SOCE were less prominent in control cells. Rapamycin also significantly reduced PDGF-stimulated cell proliferation. In conclusion, the data from this study indicate the importance of the mTOR pathway in the development of pulmonary vascular remodeling in CTEPH and suggest a potential therapeutic benefit of rapamycin (or inhibition of mTOR) in these patients.

Topics: Blotting, Western; Calcium; Cell Proliferation; Cells, Cultured; Cytosol; Endarterectomy; Fluorescent Antibody Technique; Humans; Hypertension, Pulmonary; Immunoenzyme Techniques; Muscle, Smooth, Vascular; Platelet-Derived Growth Factor; Protein Kinases; Pulmonary Artery; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; RNA, Small Interfering; Sirolimus; Thromboembolism; TOR Serine-Threonine Kinases

Topics: Diabetes Complications; Diabetes Mellitus, Type 2; Endothelium, Vascular; Humans; Immunosuppressive Agents; Sirolimus; Stents; Thromboembolism

Deep venous thrombosis (DVT) tends to occur in greater frequency among cyclosporine (CsA)-treated renal-transplant recipients. Because administration of sirolimus may increase the whole-blood concentrations of CsA, we sought to assess the impact of the combination regimen on the incidence, predisposing factors, and consequences of postoperative DVT, transplant renal-vein or artery thrombosis, and pulmonary embolus.. We retrospectively evaluated two cohorts of renal transplant recipients: CsA/prednisone (Pred)+/-azathioprine (n=136, group A) or sirolimus+CsA+Pred (n=354, group B) using Fisher's exact t and chi-square tests, as well as Kaplan-Meier analyses, odds ratios, and multiple logistic regression methods.. The 7 of 136 (5.1%) incidence of thrombotic events in group A was similar to the 20 of 354 (5.6%) incidence in group B (P=0.513; NS) and occurred no more frequently ipsilateral to the transplant. Although the occurrence of an acute-rejection episode was not associated with the DVT diagnosis, all affected patients displayed elevated serum creatinine (Scr) values, which remained slightly higher than baseline following recovery (group A 1.63+/-1.22-1.95+/-0.93 mg/dL; group B 1.70+/-1.11-2.01+/-0.88 mg/dL). Renal biopsies failed to show evidence of intrarenal coagulopathy. No patient lost a graft as a complication of DVT, nor did these events produce other lasting adverse effects. Patients in the sirolimus group showed a strong correlation between the occurrence of DVT and the previous existence of an ipsilateral or contralateral lymphocele.. Addition of sirolimus to a CsA+Pred regimen does not increase the incidence of postoperative thrombotic events among renal transplant recipients.

Topics: Adult; Anti-Inflammatory Agents; Cohort Studies; Cyclosporine; Drug Therapy, Combination; Female; Humans; Immunosuppressive Agents; Incidence; Kidney; Kidney Transplantation; Lymphocele; Male; Middle Aged; Postoperative Complications; Prednisone; Retrospective Studies; Risk Factors; Sirolimus; Thromboembolism