Immunosuppressed Organ Transplant Research Articles

Neoplastic disease after heart transplantation: single center experience.

Mandatory use of prolonged immunosuppression in organ transplantation is complicated by an increased incidence of cancer. The current study represents a retrospective analysis of the incidence of neoplasms in our heart transplantation program. Four-hundred and seventy-four patients (403 male and 71 female; mean age, 48.6+/-12.1 years), with at least 30 days of follow-up, were enrolled in this study. Patients received triple immunosuppression with cyclosporin A, azathioprine and steroids. Moreover, as a prophylactic anti-lymphocyte therapy, 388 patients (82%) were administered RATG, 67 patients (14%) received ALG and 19 patients (4%) OKT3. The mean follow-up time was 71.1+/-43.0 months. Fifty-five patients (11.6%) developed malignant neoplasms. The cancer frequencies were: solid tumors, 55%; non-Hodgkin lymphomas (NHL), 20%; Kaposi's sarcomas, 11%; skin cancers, 9%; undifferentiated sarcomas and myelomas, 5%. Solid tumors mainly affected the lung (39%), bowel (16%), stomach (6.5%), liver (6.5%), pancreas (6.5%) and oral cavity (6.5%). The times to the onset of cancer from transplantation were: Kaposi's sarcoma, 12.7+/-16.8 months; skin cancers, 34.5+/-23.8 months; solid tumors, 54.3+/-38.7 months; NHL, 60.1+/-36.4 months; undifferentiated sarcomas and myelomas, 90.0+/-15.6 months. As determined by univariate and multivariate analyses, sex, number of treated rejections, previous history of tumor, average dose of cyclosporine and prednisone and cyclosporine blood levels did not increase the incidence of malignancies. Univariate analysis suggests a significant correlation between the type of prophylactic immunoglobulins and the average dose of azathioprine with the incidence of neoplasms. Both univariate and multivariate analyses demonstrated a significant correlation between patient's age at the time of transplantation and risk of cancer occurrence (risk increased by 1.074/year; P=0.0056 with multivariate Cox regression). Cancer is a strong limitation for long-term survival after heart transplantation. The only risk factor recognized is the patient's age at the time of transplant. Furthermore, the type of prophylactic globulins used for induction therapy and some specific immunosuppressant agent (azathioprine) may play a significant role in the development of malignancies after transplantation.

Enterohepatic recirculation: a powerful incentive for drug discovery in the inosine monophosphate dehydrogenase field.

With the exception of organ transplant immunosuppression, the treatment of various IMPDH-dependent hyperproliferative diseases by MPA has failed due to the drug's EHC-induced GIT adverse effects. To influence its therapeutic index, novel formulations such as gastro-resistant MPA-Na (ERL080) or MPA/cholestyramine combinations have been developed. Structurally novel IMPDH inhibitors have been discovered based on high throughput screening (pyridazoles) and rational design (methoxyphenyloxazoles). The clinical data on methoxyphenyloxazole derivatives such as VX-497 that is not expected to undergo EHC, will bring improved understanding of the relationship between IMPDH blockade and GIT toxicity.

Intrathecal cyclosporin prolongs survival of late-stage ALS mice

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by upper and lower motor neuron death with ascending paralysis leading to death. In a transgenic mouse model of ALS (SOD1-G93A) weakness appears at 3 months of age, and because of progressive paralysis leads to death by 5 months. Cyclosporin A (CsA) is well known, for its extracerebral effect, as an immunosuppressant in organ transplantation. When able to access the brain, CsA is an effective neuroprotective agent mainly due to its protection of mitochondria through inhibition of the mitochondrial permeability transition. CsA does not cross the intact blood–brain barrier and was in the present study delivered to the brain through an infusion into the lateral cerebral ventricle. Injections started at the onset of late disease when weakness of the hindlimbs was apparent. CsA treatment prolonged the survival of ALS transgenic mice as compared to vehicle-treated controls. This finding implicates mitochondrial function in ALS and may have significance for human disease.

Gene expression profiles of rat heart allografts with immunosuppression

TRANSPLANTATION biology has entered the era of the genome. Genome analysis will provide new insights in development, differentiation, and homeostasis of host immune or nonimmune responses resulting in destruction of allograft tissues. Genome analysis also has the potential to reveal new therapeutic pathways in the treatment of organ transplantation rejection with minimal side effects. Our previous studies of remarkable cellular surface markers and cytokine gene expression in the rat heart transplantation model strongly indicated that day 5 after transplantation is an optimal time for evaluation of gene expression involved in acute allograft rejection. In addition, the studies indicated that the predetermined equivalent effective doses (optimal doses) of tacrolimus and cyclosporin (CyA), which can induce similar survival of rat heart allografts with strong histocompatibility differences, were suitable for the further comparative study of these two drugs at the genome level. In the current study, we identify candidate genes involved in host immune or nonimmune responses against allografts. Our strategy is to identify genes that are affected during graft rejection and that respond to treatment with the immunosuppressive agents tacrolimus and cyclosporin, by measuring expression levels of a large number of genes in rat heart allograft samples using microarray-based technology with cDNA clones as gene-specific hybridization targets. These gene expression profiles also allow the recognition of similarities and differences between tacrolimusand CyA-mediated immunosuppression in organ transplantation.

Immunologic Considerations for Therapeutic Strategies Utilizing Allogeneic Hepatocytes: Hepatocyte-Expressed Membrane-Bound Major Histocompatibility Complex Class I Antigen Sensitizes While Soluble Antigen Suppresses the Immune Response in Rats

Understanding the immunologic effects of hepatocytes is critical because of the potential to use these cells for bioartificial livers, as a vehicle for gene transfer, and as a means to induce donor-specific immunosuppression in organ transplantation. However, this understanding is complicated by the fact that hepatocytes express membrane-bound and soluble forms of major histocompatibility complex (MHC) class I antigen, each with the potential to induce different immune responses. In the present study we first determined the immunologic effect of normal donor-derived hepatocytes in a rat heart transplant model. We then used ex vivo hepatocyte gene transfer to examine the immunologic effects of different forms of hepatocyte-expressed MHC class I antigen. Results showed that intrasplenic injection of purified, donor-strain–specific hepatocytes into recipients primes alloimmunity, as evidenced by acceleration of heart allograft rejection. Interestingly, injection of autologous hepatocytes transfected ex vivo with DNA encoding only membrane-bound donor MHC class I antigen (RT1.A a) also accelerated allograft rejection. However, hepatocytes transfected to express only secreted donor MHC antigen prolonged transplant survival. Limiting-dilution analysis of lymphocytes from animals treated with hepatocytes producing only secreted alloantigen showed an antigen-specific reduction in cytotoxic T lymphocyte (CTL) and helper T lymphocyte (HTL) precursors. Further analysis of CTL populations by flow cytometry revealed a relatively high percentage of nonviable cells, implying that soluble antigen promotes allospecific CTL death. In summary, this study suggests that hepatocyte-expressed MHC class I molecules have opposing immunologic effects, with the membrane-bound antigen inducing immunologic sensitization, and the soluble antigen promoting donor-specific immunosuppression. (Hepatology 2000;32:999-1007.)

Future directions of clinical immunosuppression in organ transplantation: comment

Future directions of clinical immunosuppression in organ transplantation: comment

Treatment of chronic plaque-stage psoriasis and psoriatic arthritis with mycophenolate mofetil

Mycophenolate mofetil (MMF), a widely used immunosuppressant in organ transplantation, is a recent addition to the therapeutic armamentarium of autoimmune and inflammatory skin disorders in dermatology. We describe 5 patients with moderate to severe chronic plaque psoriasis and 6 patients with psoriatic arthritis that was refractory to conventional systemic and/or topical antipsoriatic treatment who were treated with MMF monotherapy (2 g/d) in a 10-week study. Although MMF was tolerated well in all patients, only patients with moderate psoriasis and psoriatic arthritis improved with therapy, whereas patients with severe psoriasis did not respond to MMF. Although MMF seems to be effective and safe for blistering autoimmune diseases and pyoderma gangrenosum, our data do not allow optimistic statements on the use of MMF in severe plaque-stage psoriasis. However, MMF may develop into an interesting therapeutic alternative for patients with psoriatic arthritis. (J Am Acad Dermatol 2000;42:835-7.)

Abacavir and Mycophenolic Acid, an Inhibitor of Inosine Monophosphate Dehydrogenase, Have Profound and Synergistic Anti-HIV Activity

The use of inhibitors of purine nucleoside metabolism has been advocated for the treatment of HIV-1 infection. Abacavir is the first clinically available guanosine analogue HIV-1 reverse transcriptase inhibitor, and the most potent nucleoside analogue yet developed. Mycophenolic acid (MA), a specific inhibitor of lymphocyte proliferation that is currently in use in organ transplantation, acts on inosine monophosphate dehydrogenase to block conversion of inosine monophosphate to guanosine monophosphate. We found abacavir and MA inhibited HIV-1 replication in stimulated peripheral blood mononuclear cells (PBMCs) and in monocyte-derived macrophages (MDMs). Inhibition was potent and synergistic to an extent not previously observed with other antiretroviral combinations. MA was effective at concentrations (0.25 microM) far below those used for immunosuppression in organ transplantation. An HIV strain encoding the M184V mutation was susceptible to the combination of MA and abacavir. However, the combination of MA and zidovudine (ZDV) or stavudine (d4T) was antagonistic. Although the translation of these observations must be carefully evaluated in clinical trials, the judicious combination of antiretrovirals and inhibitors of nucleoside metabolism may emerge as an important strategy in the treatment of HIV infection.

Sensitization following Thymoglobulin and Atgam rejection therapy as determined with a rapid enzyme-linked immunosorbent assay

Monoclonal and polyclonal anti-thymocyte preparations play an important role in solid organ transplant immunosuppression. While it is generally accepted that blocking anti-idiotypic antibodies can decrease the efficacy of retreatment with mouse monoclonal antibody preparations, sensitization levels and subsequent effects on treatment efficacy are less clear for polyclonal preparations. Serum samples were obtained from 148 patients participating in a multicentre, double-blind randomized phase III trial comparing Atgam (Pharmacia Upjohn, horse anti-thymocyte globulin) with Thymoglobulin (SangStat Medical Corporation, rabbit anti-thymocyte globulin). Recipients of a first or second renal allograft undergoing biopsy proven acute rejection were randomized to treatment with Atgam or Thymoglobulin. Serum samples were analysed for presence of anti-Thymoglobulin and anti-Atgam antibodies. Sensitization levels to rabbit IgG in Thymoglobulin-treated patients (68%, n = 54) was similar to sensitization to horse IgG in Atgam-treated patients (78%, n = 54) (two-sided p value = 0.4, Fisher's exact test), although Atgam-treated patients remained sensitized longer (at day 90, 67% anti-horse IgG positive in Atgam treated vs 24% anti-rabbit IgG in Thymoglobulin positive, p = 0.001). No difference was seen in the production of a crossreactive response. Similarly, sensitization had no significant effect on treatment success or failure. For Thymoglobulin-treated patients, the sensitization rate in successfully treated patients was 68%, while in patients with treatment failures it was 71% ( p = not significant, ns). In Atgam-treated patients, the sensitization rate in successfully treated patients was 82%, while in patients with treatment failures it was 67% ( p = ns). In conclusion, patients treated with Thymoglobulin and patients treated with Atgam exhibited similar levels of sensitization, presensitization and crossreactive sensitization, although the anti-horse response was longer lasting; neither presensitization nor treatment-induced sensitization appeared to effect treatment efficacy.

Mycophenolate mofetil in autoimmune and inflammatory skin disorders

Mycophenolate mofetil (MMF) has been widely used as an immunosuppressant in organ transplantation. MMF has recently been added to therapeutic regimens for skin disorders. Expanding the use of MMF in dermatology, we describe additional patients with autoimmune and inflammatory skin diseases, including 4 cases of pemphigus vulgaris, 1 case of pemphigus foliaceus, 1 case of perineal and metastatic cutaneous Crohn’s disease, 1 case of bullous pemphigoid and psoriasis, and 1 case of psoriasis. Most of these patients had refractory disease or had developed significant side effects to conventional therapy, including azathioprine, methotrexate, prednisone, cyclosporine, acitretin, PUVA, UVB, and tacrolimus. MMF was effective and well tolerated in all these patients. The dosages of MMF ranged from 500 mg twice daily (for psoriasis and Crohn’s disease) to 1250 mg twice daily (for 3 of 4 patients with pemphigus vulgaris). MMF is an effective and relatively safe immunosuppressant in autoimmune and inflammatory skin diseases. (J Am Acad Dermatol 1999;40:265-8.)

Toxicology and Adverse Effects of Drugs Used for Immunosuppression in Organ Transplantation

In the first half of the 20th century, attempts at organ transplantation were tried but proved unsuccessful without the conceptual understanding of rejection. As our understanding of the process of immune response expanded, attempts were made to control or modify the reaction to ensure graft survival. It seemed initially that there was an uncircumventable limitation to effective immunosuppression, in that it could not be achieved without inducing total immunodeficiency. Cyclosporine was the first drug used to produce immunosuppression without global immunodeficiency. Cyclosporine, however, was limited by excessive toxicity. Newer drugs, some undergoing clinical trials and others in the pipeline, hold the promise of exciting developments in the field of organ transplantation.

Mycophenolic acid: a new approach to the therapy of experimental mesangial proliferative glomerulonephritis.

Mycophenolate mofetil (MMF) represents a powerful immunosuppressant in organ transplantation. The aim of this study was to determine the anti-inflammatory effects of MMF on mesangial cells. Cultured rat mesangial cells were exposed to mycophenolic acid (MPA) in concentrations of 0.1 to 10 microM. MPA inhibited the proliferation of these cells in a dose-dependent manner. A maximum of 98% inhibition was obtained by a 2-d exposure of mesangial cells to > or =5 microM MPA. As expected, the addition of > or =75 microM guanosine prevented the antiproliferative effect of MPA completely. Subsequently, in vivo studies were performed in the anti-Thy1.1 nephritis model. Sixty-six male Wistar rats were investigated: healthy rats (n = 15), treated healthy rats (n = 6), nephritic rats (n = 15), and treated nephritic rats (n = 30). MMF therapy (40 mg/kg body wt per d) of nephritic animals was initiated 2 d before (n = 3) and 6 h (n = 15) or 2 d (n = 12) after induction of nephritis. Renal histology was analyzed at days +6 and +9 after initiation of disease. Therapy of nephritic rats by MMF resulted in a significant amelioration of glomerular histology, assessed by glomerular cellularity, synthesis of alpha-smooth muscle actin, extracellular matrix deposition, and glomerular hypertrophy. Proteinuria, expressed as areas under the curve of protein/creatinine ratios versus time, showed a clear tendency toward a reduction by MMF therapy. Healthy control rats were not negatively affected by exposure to MMF. In summary, this study shows that mesangial cell proliferation can be significantly inhibited by MPA in vitro and in vivo. MMF represents a new approach to the therapy of experimental mesangial cell-mediated forms of glomerulonephritis.

Kupffer Cell-Mediated Lymphocyte Apoptosis: A PGE2-Dependent Mechanism of Portal Venous Transfusion-Induced Immunosuppression?

Background.Kupffer cells, after exposure to alloantigen via the portal vein, mediate an immunosuppressive effect involving enhanced production of PGE2. We hypothesize that up-regulation of Kupffer cell CoA-independent transacylase (CoA-IT) by portal venous transfusion (PVT) is a possible mechanism of increased PGE2production. Additionally, enhanced lymphocyte apoptosis, a process known to be macrophage dependent and facilitated by PGE2, is postulated as a possible mechanism of PVT-induced, Kupffer cell-mediated immunosuppression.Methods.Lewis rat Kupffer cells were isolated after portal venous infusion with 1 ml of Wistar–Firth blood (PVT) or saline (PV sal). Kupffer cell PGE2production and CoA-IT activity was assessed. Lymphocyte apoptosis after exposure to PVT or PV sal-treated Kupffer cells was also assessed by flow cytometry.Results.PVT-treated Kupffer cells produced significantly more PGE2and had increased CoA-IT activity when compared to PV sal-treated Kupffer cells. Treatment of Kupffer cells with a selective inhibitor of CoA-IT significantly decreased PVT-induced Kupffer cell PGE2production. Increased lymphocyte apoptosis was observed after coculture with PVT-treated Kupffer cells compared to PV sal-treated cells.Conclusions.PVT increases Kupffer cell PGE2production via increased CoA-IT activity and induces Kupffer cell-mediated lymphocyte apoptosis. Lymphocyte apoptosis facilitated by Kupffer cells within the hepatic sinusoid may be an important mechanism of PVT-induced immunosuppression in organ transplantation.

Cyclosporine, but not FK506, selectively induces renal and coronary artery smooth muscle contraction

<h2>Abstract</h2> <b>Background:</b> Cyclosporine immunosuppression for organ transplantation is associated with hypertension and nephrotoxicity. Because the effects of cyclosporine as an immunosuppressant are mediated by the effect of cyclosporine as a phosphatase inhibitor, and phosphatase inhibitors are potent vascular smooth muscle contractile agents, we hypothesized that cyclosporine might induce contraction of the renal artery vascular smooth muscle directly. <b>Methods:</b> Strips of bovine renal, carotid, superior mesenteric, or coronary arteries were obtained fresh from an abattoir. The strips were equilibrated in a muscle bath, and the contractile responses to cyclosporine and FK506 were determined. <b>Results:</b> Cyclosporine (50 to 5000 μg/ml), but not FK506, induced rapidly developing, sustained contractions of renal and coronary artery smooth muscle. The magnitude of the cyclosporine-induced contractions of carotid and superior mesenteric artery smooth muscles was significantly less. The magnitude of renal artery smooth muscle contractions induced by cyclosporine was enhanced in the presence of an intact endothelium. <b>Conclusions:</b> Although these effects occurred in vitro to relatively high doses of cyclosporine, these data suggest that cyclosporine may selectively induce renal artery smooth muscle contraction through activation of the Ca²⁺-dependent phosphatase (calcineurin) in the smooth muscle, and these contractions may be enhanced by the release of endothelial-derived contracting factors. (Surgery 1998;123:456-60.)

Cyclosporine, but not FK506, selectively induces renal and coronary artery smooth muscle contraction

Background: Cyclosporine immunosuppression for organ transplantation is associated with hypertension and nephrotoxicity. Because the effects of cyclosporine as an immunosuppressant are mediated by the effect of cyclosporine as a phosphatase inhibitor, and phosphatase inhibitors are potent vascular smooth muscle contractile agents, we hypothesized that cyclosporine might induce contraction of the renal artery vascular smooth muscle directly. Methods: Strips of bovine renal, carotid, superior mesenteric, or coronary arteries were obtained fresh from an abattoir. The strips were equilibrated in a muscle bath, and the contractile responses to cyclosporine and FK506 were determined. Results: Cyclosporine (50 to 5000 μg/ml), but not FK506, induced rapidly developing, sustained contractions of renal and coronary artery smooth muscle. The magnitude of the cyclosporine-induced contractions of carotid and superior mesenteric artery smooth muscles was significantly less. The magnitude of renal artery smooth muscle contractions induced by cyclosporine was enhanced in the presence of an intact endothelium. Conclusions: Although these effects occurred in vitro to relatively high doses of cyclosporine, these data suggest that cyclosporine may selectively induce renal artery smooth muscle contraction through activation of the Ca 2+-dependent phosphatase (calcineurin) in the smooth muscle, and these contractions may be enhanced by the release of endothelial-derived contracting factors. (Surgery 1998;123:456-60.)

28.4 Late results of cryopreserved arterial allografts in patients receiving immunosuppression for organ transplantation

28.4 Late results of cryopreserved arterial allografts in patients receiving immunosuppression for organ transplantation

When to investigate for purine and pyrimidine disorders. Introduction and review of clinical and laboratory indications.

When to suspect and thus investigate for inborn errors of purine and pyrimidine metabolism is a dilemma for even the most observant investigator. Often parents of affected children, or a history involving siblings, can provide valuable clues. The recognition of new purine and pyrimidine disorders requires skill and serendipity. But even identifying known disorders can prove difficult, since they cover a broad spectrum of illnesses, can have more than one symptom, or lead to early death. This problem is compounded by the fact that they are relatively recently described and therefore often little known, either in the clinic or laboratory. The considerable heterogeneity in clinical expression within families as well as between families means that asymptomatic homozygotes may not be recognized or can present at any time from early childhood through adolescence up to their eighth decade. Consequently, all siblings should be screened. These disorders should be suspected in any case of unexplained anaemia, failure to thrive, susceptibility to recurrent infection, or neurological deficits with no current diagnosis, including autism, cerebral palsy, delayed development, deafness, epilepsy, self-mutilation, muscle weakness, the inability to walk or talk, and-unusual in children and adolescents-gout, sometimes with renal disease. Some disorders present with radiolucent kidney stones, in acute or chronic renal failure, alone or with any of the above, or as an intolerance/sensitivity to therapy (e.g. 5-fluorouracil in malignancies or azathioprine immunosuppression in organ transplantation), often with life-threatening consequences. Several parameters need to be evaluated to ensure correct diagnosis. Pitfalls which can mask diagnosis using only a single test are renal failure, blood transfusion, diet or drugs.

The politics of grafting cadaver kidneys

The politics of grafting cadaver kidneys

A logistic-regression model provides novel guidelines to maximize the anti-acute rejection properties of cyclosporine with a minimum of toxicity.

Although cyclosporine has become the mainstay of immunosuppression in organ transplantation, there is still no consensus on the criteria to optimize its anti-rejection activity with minimum toxicity. A clear and objective definition of target cyclosporine trough levels at different times from renal transplantation is still lacking, primarily because of the lack of a model correlating cyclosporine levels with probability of rejection or toxicity. In this study, logistic-regression model was developed that was applied to data collected retrospectively from two postoperative periods, i.e., Days 0 to 9 and 10 to 30, in 135 consecutive cadaveric renal transplant recipients, for a total of 1851 determinations. Only minimum and maximum trough levels were considered for each period. Concentration-response curves were estimated for Days 0 to 9 (P = 0.0001 for efficacy and P = 0.028 for toxicity) and for Days 10 to 30 (P = 0.015 for efficacy and P = 0.037 for toxicity). Therapeutic intervals of 330 to 430 ng/mL (parent compound in whole blood) for Days 0 to 9 and 260 to 390 ng/mL for Days 10 to 30 predicted an incidence of acute rejection of 22% and 12%, respectively, with a reasonably low toxicity that primarily consisted of elevation of serum aminotransferases.

Novel mechanisms of brequinar sodium immunosuppression on T cell activation.

Brequinar sodium (BQR) is a novel immunosuppressive agent that acts by inhibiting the activity of dihydroorotate dehydrogenase, the fourth enzyme in the de novo pyrimidine biosynthetic pathway. The activity of BQR as an immunosuppressive agent is believed to be inhibition of antigen-induced lymphocyte proliferation through inhibition of DNA and RNA synthesis. BQR, therefore, has a different mechanism of action than cyclosporine and may potentiate the immunosuppressive effects of cyclosporine. In this study, we determined the effect of BQR on peripheral blood mononuclear cell (PBMC) activation in a series of in vitro culture systems. In these studies, BQR inhibited PHA-stimulated activation in a dose-dependent fashion beginning at 10(-6) M. The immunosuppressive effect of BQR was similar in magnitude to cyclosporine. Proliferation assays suggested an additive immunosuppression by the combination of BQR and cyclosporine. Similar inhibition of CD2-stimulated or CD3-stimulated activation of PBMC was found. The mechanisms of action of BQR were complex. BQR inhibited interleukin 2 protein production in response to mitogen stimulation. Cell surface interleukin 2 receptor expression was inhibited by BQR. BQR inhibited cell cycle progression, preventing progression from G0/G1 into S and G2 + M phases. BQR had no effect on induction of transcripts for the interleukin 2 receptor, but markedly inhibited the production of transcripts for interleukin 2. Thus, our studies indicate that BQR exerts a potent immunosuppression on mitogen-induced PBMC activation through multiple mechanisms. Consequently, BQR may be an effective agent for immunosuppression in organ transplantation or inflammatory diseases.