Andrea Bontadini

High incidence of allograft dysfunction in liver transplanted patients treated with pegylated-interferon alpha-2b and ribavirin for hepatitis C recurrence: possible de novo autoimmune hepatitis?

Background: Interferon may trigger autoimmune disorders, including autoimmune hepatitis, in immunocompetent patients. To date, no such disorders have been described in liver transplanted patients. Methods: 9 of 44 liver transplanted patients who had been receiving pegylated-interferon alpha-2b and ribavirin for at least 6 months for hepatitis C virus (HCV) recurrence, developed graft dysfunction despite on-treatment HCV-RNA clearance in all but one case. Laboratory, microbiological, imaging and histological evaluations were performed to identify the origin of graft dysfunction. The International Autoimmune Hepatitis scoring system was also applied. Results: In all cases infections, anastomoses complications and rejection were excluded, whereas the autoimmune hepatitis score suggested a “probable autoimmune hepatitis” (score from 10 to 14). Three patients developed other definite autoimmune disorders (overlap anti-mitochondrial antibodies (AMA)-positive cholangitis, autoimmune thyroiditis and systemic lupus erythematosus, respectively). In all cases, pre-existing autoimmune hepatitis was excluded. Anti-lymphocyte antibodies in immunosuppressive induction treatment correlated with the development of the disorder, whereas the use of granulocyte colony-stimulating factor to treat interferon-induced neutropenia showed a protective role. Withdrawal of antiviral treatment and treatment with prednisone resulted in different outcomes (five remissions and four graft failures with two deaths). Conclusions: De novo autoimmune hepatitis should be considered in differential diagnosis along with rejection in liver transplanted patients developing graft dysfunction while on treatment with interferon.

Synergistic proapoptotic activity of recombinant TRAIL plus the Akt inhibitor Perifosine in acute myelogenous leukemia cells.

To potentiate the response of acute myelogenous leukemia (AML) cells to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) cytotoxicity, we have examined the efficacy of a combination with perifosine, a novel phosphatidylinositol-3-kinase (PI3K)/Akt signaling inhibitor. The rationale for using such a combination is that perifosine was recently described to increase TRAIL-R2 receptor expression and decrease the cellular FLICE-inhibitory protein (cFLIP) in human lung cancer cell lines. Perifosine and TRAIL both induced cell death by apoptosis in the THP-1 AML cell line, which is characterized by constitutive PI3K/Akt activation, but lacks functional p53. Perifosine, at concentrations below IC(50), dephosphorylated Akt and increased TRAIL-R2 levels, as shown by Western blot, reverse transcription-PCR, and flow cytometric analysis. Perifosine also decreased the long isoform of cFLIP (cFLIP-L) and the X-linked inhibitor of apoptosis protein (XIAP) expression. Perifosine and TRAIL synergized to activate caspase-8 and induce apoptosis, which was blocked by a caspase-8-selective inhibitor. Up-regulation of TRAIL-R2 expression was dependent on a protein kinase Calpha/c-Jun-NH(2)-kinase 2/c-Jun signaling pathway activated by perifosine through reactive oxygen species production. Perifosine also synergized with TRAIL in primary AML cells displaying constitutive activation of the Akt pathway by inducing apoptosis, Akt dephosphorylation, TRAIL-R2 up-regulation, cFLIP-L and XIAP down-regulation, and c-Jun phosphorylation. The combined treatment negatively affected the clonogenic activity of CD34(+) cells from patients with AML. In contrast, CD34(+) cells from healthy donors were resistant to perifosine and TRAIL treatment. Our findings suggest that the combination of perifosine and TRAIL might offer a novel therapeutic strategy for AML.

Quantitatively different red cell/nucleated cell chimerism in patients with long-term, persistent hematopoietic mixed chimerism after bone marrow transplantation for thalassemia major or sickle cell disease

Background Persistent mixed chimerism represents a state in which recipient and donor cells stably co-exist after hematopoietic stem cell transplantation. However, since in most of the studies reported in literature the engraftment state was observed in the nucleated cells, in this study we determined the donor origin of the mature erythrocytes of patients with persistent mixed chimerism after transplantation for hemoglobinopathies. Results were compared with the engraftment state observed in singly picked out burst-forming unit – erythroid colonies and in the nucleated cells collected from the peripheral blood and from the bone marrow. Design and Methods The donor origin of the erythrocytes was determined analyzing differences on the surface antigens of the erythrocyte suspension after incubation with anti-ABO and/or anti-C, -c, -D, -E and -e monoclonal antibodies by a flow cytometer. Analysis of short tandem repeats was used to determine the donor origin of nucleated cells and burst-forming unit – erythroid colonies singly picked out after 14 days of incubation. Results The proportions of donor-derived nucleated cells in four transplanted patients affected by hemoglobinopathies were 71%, 46%, 15% and 25% at day 1364, 1385, 1314 and 932, respectively. Similar results were obtained for the erythroid precursors, analyzing the donor/recipient origin of the burst-forming unit – erythroid colonies. In contrast, on the same days of observation, the proportions of donor-derived erythrocytes in the four patients with persistent mixed chimerism were 100%, 100%, 73% and 90%. Conclusions Our results showed that most of the erythrocytes present in four long-term transplanted patients affected by hemoglobinopathies and characterized by the presence of few donor engrafted nucleated cells were of donor origin. The indication that small proportions of donor engrafted cells might be sufficient for clinical control of the disease in patients affected by hemoglobinopathies is relevant, although the biological mechanisms underlying these observations need further investigation.

Interactions between Shiga toxins and human polymorphonuclear leukocytes

Human intestinal infections by Shiga toxin (Stx)‐producing Escherichia coli cause hemorrhagic colitis and hemolytic uremic syndrome (HUS), which represents the main cause of acute renal failure in early childhood. In HUS, Stx released in the gut enter the bloodstream and are targeted to renal endothelium. The mechanism of toxin delivery is still a matter of debate, although the role of polymorphonuclear leukocytes (PMN) as a Stx carrier has been indicated. The aim of this paper was to better define the interactions between Stx and human PMN. Direct and indirect flow cytometric analysis and binding experiments with radiolabeled toxins demonstrated that Stx bind to the surface of human mature PMN but not to immature PMN from G‐CSF‐treated donors. The use of the human myeloid leukemia cell (HL‐60) model for inducible cell differentiation confirmed that the toxin binding occurs only after granulocytic differentiation. Stx binding caused a delay of the spontaneous apoptosis of PMN, as shown by the delayed appearance of apoptotic nuclei and activation of caspase 3 and by the higher number of cells negative to the annexin V‐binding assay after 48 h. Moreover, flow cytometric analysis of mixed Stx‐positive and Stx‐negative PMN populations showed that the toxins were transferred from positive to negative PMN. The delayed, spontaneous apoptosis and the passage of the toxic ligand from older PMN to new, mature cells entering the circulation from the bone marrow may explain the previously reported persistence of Stx in the blood of children with HUS.

Liver transplantation from hepatitis B surface antigen positive donors: A safe way to expand the donor pool

BACKGROUND & AIMSnThe main limitation of orthotopic liver transplantation (OLT) is the scarcity of available donor organs. A possibility to increase the organ pool is to use grafts from hepatitis B virus surface antigen (HBsAg) positive donors, but few data are currently available in this setting. We assessed the clinical, serovirological, and immunological outcomes of liver transplant from HBsAg positive donors in a single centre study.nnnMETHODSnFrom 2005 to 2009 10 patients underwent OLT from HBsAg positive donors, for HBV-related disease (n=6) or HBV-unrelated disease (n=4). The median follow-up was 42 months (range 12-60). All recipients were HBcAb positive and were given antiviral prophylaxis.nnnRESULTSnPatients transplanted for HBV-related disease never cleared HBsAg. Two HBsAg negative patients never tested positive for HBsAg, whereas the others experienced an HBsAg appearance, followed by spontaneous production of anti-HBs, allowing HBsAg clearance. No patient ever had any sign of HBV hepatitis. HBV replication was effectively controlled by antiviral therapy. The immunologic sub-study showed that a most robust anti-HBV specific T cell response was associated with the control of HBV infection.nnnCONCLUSIONSnOLT from HBsAg positive donors seems to be a safe procedure in the era of highly effective antiviral therapy.

Endothelial damage induced by Shiga toxins delivered by neutrophils during transmigration

The endothelial damage induced by Stx represents the main pathogenic event in the HUS associated with STEC infections in humans. Stx, released in the gut by bacteria, enter the bloodstream and are targeted to renal endothelia. The role of PMN as a toxin carrier has been the object of controversy. In this paper, we confirm the binding of Stx1 to PMN, also showing its degranulating effects on full‐loaded leukocytes, and support the carrier role of PMN by using a two‐chamber transmigration device, in which PMN, loaded in vitro with different amounts of Stx1, transmigrated through confluent monolayers of endothelial cells, mimicking the toxin‐induced renal endothelial injury. Stx1 was transferred during PMN transmigration, impairing protein synthesis and triggering production of proinflammatory cytokines in endothelial cells. PMN, carrying low toxin amounts, induced the release of high levels of cytokines in viable endothelial cells, whereas cytokine production was blocked in cells challenged with PMN fully loaded with Stx as a result of an almost total impairment of translation and of the activation of the apoptotic program. In agreement with previous unexplained observations in animal models, the results obtained with our experimental setting suggest that a self‐amplifying circle triggered by low doses of toxin may lead to the production of proinflammatory mediators of renal damage in HUS.

An immunotoxin containing momordin suitable for bone marrow purging in multiple myeloma patients.

Attempts have been made by a number of methods to eliminate minimal residual disease from bone marrow to be reinfused in autologous transplantation. In this paper we describe a conjugate containing a monoclonal antibody, named 8A, recognising a plasma cell-associated antigen, and momordin, a ribosome-inactivating protein similar to the ricin A-chain. This immunotoxin is active on target cell lines and on neoplastic plasma cells, while myeloid progenitors are fairly resistant. The conjugate is shown to be acceptable for ex vivo purging in autologous bone marrow transplantation in multiple myeloma patients.

Anti-HBs re-seroconversion after liver transplantation in a patient with past HBV infection receiving a HBsAg positive graft

BACKGROUND/AIMSnOrthotopic liver transplantation (OLT) is an important therapeutic option for HBV-related end-stage-liver disease, yet it is often hampered by a scarcity of organ availability. One option to increase organ availability is the use of virologically compromised organs from HBV-infected donors. Transplantation of anti-HBcore positive grafts has been associated with a low risk of HBV recurrence if adequately treated with nucleoside analogs, irrespective of concomitant HBV-specific immunoglobulin therapy. Experience using HBsAg positive grafts is, however, very limited.nnnMETHODSnHere, the analysis of the cellular and humoral HBV-specific immunity of a subject with past HBV infection (anti-HBs and anti-HBc positive) receiving an HBsAg positive liver graft is reported.nnnRESULTSnNine months post-OLT, the patient experienced a spontaneous anti-HBs re-seroconversion allowing the discontinuation of HBIG. The data show a concurrent increase in the cellular and humoral immunity at times of reduced viral antigenemia, demonstrating effective immune control of HBV post-OLT.nnnCONCLUSIONSnThese data support the use of marginal organs in this setting, providing a potential strategy to further alleviate organ shortage.

Autologous bone marrow transplantation with immunotoxin‐purged marrow for advanced multiple myeloma

A system to purge the bone marrow of myeloma cells has been developed in our laboratories with the aim of treating with myeloablative radiochemotherapy patients suffering from advanced multiple myeloma. This system is based on the ex vivo incubation of the marrow with an immunotoxin composed of the 8A monoclonal antibody — that recognizes plasma cells and B‐cell precursors — and the ribosome‐inactivating protein momordin. 8 patients have so far been treated. 4 are surviving from 4 to 18 months after ABMT, whereas 4 died after 1 to 6 months, 2 from infections, 1 from relapsing disease and 1 from veno‐occlusive disease. A marked tumour reduction was observed in all evaluable patients; however, none has achieved complete disappearance of the disease. The hæmopoietic reconstitution was significantly delayed in 3 patients. These preliminary results show the feasibility of this approach in advanced MM patients with heavily infiltrated marrow. The place of ABMT in the treatment of MM remains to be determined; the selection of patients with still responding and less advanced disease would probably produce better results.

Immunotoxins containing saporin 6 and monoclonal antibodies recognizing plasma cell-associated antigens: effects on target cells and on normal myeloid precursors (CFU-GM)

Monoclonal antibodies 8A and 62B1, recognizing plasma cell‐associated antigens, were covalently linked to saporin 6, a ribosome‐inactivating protein similar to the A‐chain of ricin. Both immunotoxins were tested on target human cell lines U266 and Raji, on non‐target K562 cell line and on myeloid CFU‐GM progenitors. The cloning efficiency and viability of target cells were strongly reduced by 8A‐saporin 6 and 62B1‐saporin 6 immunotoxins, with an ID50 up to 200000‐fold lower than free saporin 6, whilst the K562 non‐target cell line was unaffected. Normal human myeloid precursors (CFU‐GM) were inhibited by immunotoxins only to a limited extent. An application of this model for autologous bone marrow transplantation in multiple myeloma patients is proposed. Since no eradication of cloning target cells was achieved by a single immunotoxin, mixtures made with different antibodies could help to reach this goal.