Management Of Solid Organ Transplantation Research Articles

Evaluation of different microbead volumes in a single antigen bead assay for HLA antibody detection

Abstract OBJECTIVE S: The multiplexed single antigen bead (SAB) assay is now commonly used for detection of antibodies to human leukocyte antigens (HLA) in the management of solid organ transplantation. Serum is incubated with microbeads individually coated with unique HLA antigens and the presence of antibody is detected using a secondary antibody. Due to its cost, laboratories may use a lower-than-recommended volume of reagent microbeads, although the impact of microbead volume on assay performance has not been reported. The present study seeks to determine the concordance of an SAB assay when different microbead volumes were used. Although this is also a required laboratory practice when modifications are made to an FDA-cleared assay, requirements for the validation of a multiplexed assay are currently not well-standardized. Hence, this study may also serve as an example framework for validating a clinical multiplexed assay. METHODS SAB (LabScreen, One Lambda) was performed on 14 patient specimens [Mei San T1] selected to provide a range of class I and II HLA antibody levels. Each specimen was tested using three microbead volumes of 5 μL (manufacturer-recommended), 3 μL and 2.5 μL. All reactions were tested in a single session to minimize sources of variability. A mean fluorescence intensity (MFI) of ≥ 2000 was used to define positive beads, which is also the institutional threshold for defining incompatible antigens in solid organ transplantation. Concordance between different bead volumes was calculated using Cohen’s Kappa. Bland-Altman plots were used to visualize bias. All analyses were performed at individual bead level. RESULTS Kappa values were: 0.91 (class I) and 0.95 (class II) for 3 μL vs. 5 μL; 0.90 (class I) and 0.93 (class II) for 2.5 μL vs. 5 µL; 0.97 (class I) and 0.93 (class II) for 2.5 μL vs. 3 μL. Positive bias in MFI values was observed with lower bead volumes and was most pronounced in the 2.5 μL vs. 5 μL comparison; in contrast, MFI values between 2.5 µL and 3 µL were more similar. CONCLUSION Lower-than-recommended microbead volume may be used in the SAB assay without significant impact on classification of incompatible antigens. Although positive bias in MFI values was observed with lower microbead volumes, the impact on positive vs. negative beads assignment was minimal. Since the tested microbead volumes represented 12.5-20% of the total reaction volume, such a change could have caused a matrix effect and impacted antibody-bead binding, leading to differences in MFI values. Hence, individual laboratories modifying the SAB assay should validate such modifications before implementation to ensure the accuracy of HLA antibody assignment.

De novo malignancies after liver transplantation: The effect of immunosuppression-personal data and review of literature.

BACKGROUNDImmunosuppression has undoubtedly raised the overall positive outcomes in the post-operative management of solid organ transplantation. However, long-term exposure to immunosuppression is associated with critical systemic morbidities. De novo malignancies following orthotopic liver transplants (OLTs) are a serious threat in pediatric and adult transplant individuals. Data from different experiences were reported and compared to assess the connection between immunosuppression and de novo malignancies in liver transplant patients.AIMTo study the role of immunosuppression on the incidence of de novo malignancies in liver transplant recipients.METHODSA systematic literature examination about de novo malignancies and immunosuppression weaning in adult and pediatric OLT recipients was described in the present review. Worldwide data were collected from highly qualified institutions performing OLTs. Patient follow-up, immunosuppression discontinuation and incidence of de novo malignancies were reported. Likewise, the review assesses the differences in adult and pediatric recipients by describing the adopted immunosuppression regimens and the different type of diagnosed solid and blood malignancy.RESULTSEmerging evidence suggests that the liver is an immunologically privileged organ able to support immunosuppression discontinuation in carefully selected recipients. Malignancies are often detected in liver transplant patients undergoing daily immunosuppression regimens. Post-transplant lymphoproliferative diseases and skin tumors are the most detected de novo malignancies in the pediatric and adult OLT population, respectively. To date, immunosuppression withdrawal has been achieved in up to 40% and 60% of well-selected adult and pediatric recipients, respectively. In both populations, a clear benefit of immunosuppression weaning protocols on de novo malignancies is difficult to ascertain because data have not been specified in most of the clinical experiences.CONCLUSIONThe selected populations of tolerant pediatric and adult liver transplant recipients greatly benefit from immunosuppression weaning. There is still no strong clinical evidence on the usefulness of immunosuppression withdrawal in OLT recipients on malignancies. An interesting focus is represented by the complete reconstitution of the immunological pathways that could help in decreasing the incidence of de novo malignancies and may also help in treating liver transplant patients suffering from cancer.

From Incompatibility to Accommodation – The Journey of Taming ‘Self’: Guide to Perioperative Management of Solid Organ Transplantation across ABO and Rh Barrier

The fate of every organ allografting is ‚rejection’ if nothing is done to halt this natural process. The risks of ‘hyperacute’ ‘accelerated acute’ and ‘acute’ rejection have restricted scientists and clinicians over the years in performing organ transplantationwithin ABO blood group matched pairs only. Subsequent to the development in the field of immunosuppression, ABO incompatible transplants have gained momentum to incorporate a significant population of end stage renal disease patients with incompatible blood group donors into the transplant program. However, optimizing the recipient for transplantation and subsequent accommodation with optimal graft function without tilting to the much easier path of rejection is a challenge. Although most of these steps come under the domain of the nephrologist, it is crucial that as the perioperative physician of a very high stake life modifying surgery, the anesthesiologist, surgeons as well as the intensivist should understand the complex process of desensitization, patient preparation and perioperative management for the best outcome. Lack of understanding about a couple of crucial considerations can jeopardize the delicate balance of immunotolerance and can prove catastrophic. The article highlights these considerations important for the perioperative clinicians along with a description of first 20 patients of blood group incompatible renal transplantation at our Institute.

Natriuretic Peptides in the Management of Solid Organ Transplantation Associated Acute Kidney Injury: A Systematic Review and Meta-Analysis

Randomized controlled trials involving natriuretic peptide administration in solid organ transplantation setting have shown inconsistent effects for renal endpoints. We conducted a systematic review and meta-analysis of these trials to ascertain the role of natriuretic peptides in the management of solid organ transplantation associated acute kidney injury (AKI). MEDLINE, EMBASE, and Google scholar were searched independently by two authors for randomized trials evaluating renal effects of natriuretic peptides in solid organ transplantation settings. Two reviewers independently assessed the studies for eligibility and extracted the relevant data. The pooled estimate showed that natriuretic peptide administration is associated with a reduction in AKI requiring dialysis (odds ratio = 0.50 [0.26–0.97]), a statistically nonsignificant trend toward improvement in posttransplant creatinine clearance (weighted mean difference = 5.5 mL/min, [−1.3 to 12.2 mL/min]), and reduction in renal replacement requirement duration (weighted mean difference −44.0 hours, [−60.5 to −27.5 hours]). There were no mortality events and no adverse events related to natriuretic peptides. In conclusion, administration of natriuretic peptides in solid organ transplantation may be associated with significant improvements in renal outcomes. These observations need to be confirmed in an adequately powered, prospective multicenter study.

The protective effect of epicatchin against oxidative stress and nephrotoxicity in rats induced by cyclosporine

Cyclosporine A (CyA) is the first-line immunosuppressant used for the management of solid organ transplantation and autoimmune diseases. Reactive oxygen species (ROS) can attack all types of macromolecules including DNA and damage it. Epicatechin (EC) is one of the most potent antioxidants present in the human diet. Particularly high levels of this compound are found in tea, apples, and chocolate. The goal of this study was to evaluate the protective effect of EC against CyA toxicity and its antioxidant activity in transplanted patients to avoid its side effects. Results obtained showed that, CyA exert its toxic effect by increasing the free radicals and ROS that causes lipid peroxidation and cell damage, this is detected by elevation of hydroperoxides and thiobarbituric acid reactive substances, while the activities of antioxidant enzymes include (superoxide dismutase [SOD], catalase [CAT] and glutathione peroxidase [GPx]) were significantly decreased as compared with control rats. The deleterious toxic effects of CyA are, at least in part, due to increased production of free radicals and ROS. Treatment of rats with epicatchin ameliorates the toxicity of CyA by decreasing the lipid peroxidation and enhanced the antioxidants enzyme activities.

A Case Study of a Lichenoid Drug Eruption due to Oral Cyclosporine

RATIONALE: In 1929, the first lichenoid drug eruption was reported in association with arsenic therapy. Such a rash resulting from cyclosporine has not been reported in the literature despite widespread use since the early 1980's in the management of solid organ transplantation.

Beyond Cyclosporine: A Systematic Review of Limited Sampling Strategies for Other Immunosuppressants

Therapeutic drug monitoring has gained much attention in the management of immunosuppressive therapy. Area under the plasma drug concentration-time curve (AUC) is the pharmacokinetic (PK) parameter most commonly used to assess total exposure to a drug. However, estimation of AUC requires multiple blood samples throughout the dosing period, which is often inconvenient and expensive. Limited sampling strategies (LSSs) are therefore developed to estimate AUC and other PK parameters accurately and precisely while minimizing the number of blood samples needed. This greatly reduces costs, labor and inconvenience for both patients and clinical staff. In the therapeutic management of solid organ transplantation, LSSs for cyclosporine are commonplace and have been extensively reviewed. Thus, this systematic review paper focuses on other immunosuppressive agents and categorizes the 24 pertinent citations according to the U.S. Preventive Services Task Force rating scale. Thirteen articles (3 level I, 1 level II-1, 2 level II-2, and 7 level III) involved LSSs for mycophenolate, 7 citations (1 level I and 6 level III) for tacrolimus (TAC), and 3 citations (all level III) for other drugs (sirolimus) or multiple drugs. The 2 main approaches to establishing LSSs, multiple regression and Bayesian analyses, are also reviewed. Important elements to consider for future LSS studies, including proper validation of LSSs, convenient sampling times, and application of LSSs to the appropriate patient population and drug formulation are discussed. Limited sampling strategies are a useful tool to help clinicians make decisions on drug therapy. However, patients' pathophysiology, environmental and genetic factors, and pharmacologic response to therapy, in conjunction with PK profiling tools such as LSSs, should be considered collectively for optimal therapy management.

TAURINE ATTENUATES HYPERTENSION AND RENAL DYSFUNCTION INDUCED BY CYCLOSPORINE A IN RATS

Cyclosporine A (CsA) is the first-line immunosuppressant used for the management of solid organ transplantation and autoimmune diseases. Nephrotoxicity is the major limitation of CsA use. Recent evidence suggests that reactive oxygen species (ROS) play an important role in mediating CsA-induced hypertension and nephrotoxicity. Taurine, the major intracellular free beta-amino acid, is known to be an endogenous anti-oxidant and membrane-stabilizing agent. The present study was designed to investigate the effects of taurine on CsA-induced oxidative stress, hypertension and renal dysfunction. 2. Animals were assigned into four groups of seven rats each as follows: (i) control group, receiving vehicle (olive oil; 1 mL/kg, s.c.); (ii) CsA group, given CsA (25 mg/kg per day, s.c.) for 21 days; (iii) taurine group, supplemented with taurine (1% in the drinking water); and (iv) taurine + CsA group, treated with taurine 3 days before and concurrently during CsA injections for 21 days. 3. Cyclosporine A administration elevated blood pressure, reduced serum nitric oxide (NO) levels and deteriorated renal function, as assessed by increased serum creatinine levels and proteinuria and reduced urine flow rate and creatinine clearance compared with vehicle-treated rats. Cyclosporine A induced oxidative stress, as indicated by increased renal tissue concentrations of thiobarbituric acid-reactive substances and reduced concentrations of renal glutathione, glutathione peroxidase and superoxide dismutase. Conversely, no change was noted in renal catalase activity. Moreover, the kidneys of CsA-treated rats showed interstitial inflammation and renal tubular atrophy. 4. Taurine markedly reduced elevated blood pressure, attenuated renal dysfunction and the reduction in serum NO levels and counteracted the deleterious effects of CsA on oxidative stress markers. Furthermore, taurine ameliorated CsA-induced morphological changes. 5. These data clearly indicate the protective potential of taurine against CsA-induced hypertension and nephrotoxicity and suggest a significant contribution of its anti-oxidant property to this beneficial effect.

Salvage of Cyclosporine A-Induced Oxidative Stress and Renal Dysfunction by Carvedilol

Background: Cyclosporine A (CsA) is the first-line immunosuppressant employed for the management of solid organ transplantation and autoimmune diseases. Nephrotoxicity is the major limitation of CsA use. Recent evidence suggests that reactive oxygen species (ROS) play an important role in mediating CsA nephrotoxicity. The present study was designed to investigate effects of carvedilol, a third-generation β-blocker with potent free radical-scavenging activity on CsA-induced oxidative stress and resultant renal dysfunction in a rat model of chronic CsA nephrotoxicity. Methods: Carvedilol (2.0 and 4.0 mg/kg i.p.) and propranolol (10 mg/kg i.p.) were administered to separate group of animals 24 h before and concurrently with CsA (20 mg/kg s.c.) for 21 days. Renal function was assessed by estimating plasma creatinine, blood urea nitrogen (BUN), creatinine and urea clearance. Tissue lipid peroxidation was measured as thiobarbituric acid-reacting substances (TBARS). Renal morphological alterations were assessed by histopathological examination of hematoxylin-eosin, PAS and Masson’s trichrome stained sections of the kidneys. Results: CsA (20 mg/kg s.c) administration for 21 days produced elevated levels of TBARS and deteriorated renal function as assessed by increased plasma creatinine, BUN and decreased creatinine and urea clearance as compared to vehicle-treated rats. The kidneys of CsA-treated rats showed severe striped interstitial fibrosis, arteriolopathy, glomerular basement thickening, tubular vacuolization and hyaline casts. Propranolol neither decreased TBARS nor improved the renal dysfunction and morphological changes induced by CsA. Both doses of carvedilol markedly reduced elevated levels of TBARS, whereas the higher dose of carvedilol significantly attenuated renal dysfunction and morphological changes in CsA-treated rats. Conclusion: These data clearly indicate the renoprotective potential of carvedilol in CsA-induced nephrotoxicity and suggest a significant contribution of its antilipoperoxidative property in this beneficial effect.

OXIDATIVE STRESS-MEDIATED RENAL DYSFUNCTION BY CYCLOSPORINE A IN RATS: ATTENUATION BY TRIMETAZIDINE

Cyclosporine A (CsA) is one of the first line immunosuppressants employed in the management of solid organ transplantation and autoimmune diseases. The clinical utility of CsA is limited by the frequent occurrence of chronic nephrotoxicity, characterized by tubular atrophy, interstitial fibrosis and progressive renal impairment. The pathogenesis of CsA nephrotoxicity is still not well delineated. Recent evidences suggest that reactive oxygen species (ROS) play an important role in CsA nephrotoxicity. The present study was designed to demonstrate the role of oxidative stress, its relation to renal dysfunction and to investigate the effect of trimetazidine (TMZ), an anti-ischemic agent with free radical scavenging property, in CsA-induced nephrotoxicity. TMZ (2.5 mg/kg, p.o., twice a day) was administered 24 h before and 21 days concurrently with CsA (20 mg/kg, s.c.). Tissue lipid peroxidation was measured as thiobarbituric acid reacting substances (TBARS). Renal function was assessed by measuring the plasma and urine creatinine concentrations, blood and urine urea nitrogen levels and the creatinine and urea clearances. Renal morphological alterations were assessed by histopathological examination of Hematoxylin-Eosin, PAS and Masson's trichome stained sections of the kidneys. CsA (20 mg/kg, s.c) administration for 21 days produced elevated levels of TBARS and decreased renal function as assessed by increased plasma creatinine, BUN and decreased creatinine and urea clearances as compared to vehicle treated rats. The kidneys of CsA treated rats showed severe striped interstitial fibrosis, arteriolopathy, glomerular basement thickening, tubular vacuolization and hyaline casts. TMZ (2.5 mg/kg) markedly reduced elevated levels of TBARS, significantly attenuated renal dysfunction and the morphological changes in CsA treated rats. These results clearly demonstrate the pivotal role of reactive oxygen species and their relation to renal dysfunction and point to the therapeutic potential of an anti-ischemic agent, trimetazidine, in CsA-induced nephrotoxicity.