The changing face of adult posttransplant lymphoproliferative disorder: Changes in histology between 1999 and 2013.

Posttransplant lymphoproliferative disorder (PTLD) typically presents with either polymorphic or monomorphic histology. While both are the end result of immunosuppressive therapies, their origins are felt to be different with different prognoses and responsiveness to therapy, resulting in 2 different malignancies. We attempted to confirm reports suggesting that the relative frequency of these 2 histologies is shifting over time. We analyzed 3040 adult PTLD cases in the UNOS OPTN database from 1999 to 2013. Changes in PTLD cases over time were analyzed for histology, time from transplant to diagnosis, and patient EBV serostatus. We found that the relative proportion of polymorphic versus monomorphic histology has changed with an increase in the proportion of monomorphic cases with time (1999-2003, 54.9% vs. 45.1%; 2004-2008, 58.3% vs. 41.7%; 2009-2013, 69.7% vs. 30.3%; P = <.001). The change is driven by a gradual increase in the number of monomorphic PTLD with a steady number of polymorphic PTLD. The change is most strongly seen in transplant recipients who were EBV serostatus positive at the time of transplant. Potential causes are changes in immunosuppressive regimens with increased tacrolimus use (P = .009) and increased survival among transplant patients leading to later occurrence of PTLD (P = .001) that have occurred during the time frame analyzed. As organ transplantation has evolved over time, PTLD has coevolved. These changes in histology have important implications regarding the origin and clinical management of PTLD.

Primary diffuse large B-cell lymphoma of the CNS: a rare case of spontaneous remission.

There is no consensus on the optimal therapy for primary CNS lymphoma. Conventional treatment modalities include chemotherapy and radiation therapy, which carry significant risks of morbidity and mortality. In systemic lymphomas, there are situations where non-Hodgkin lymphomas have resolved spontaneously. We now report the case of a nonimmunocompromised patient with primary CNS lymphoma who underwent a spontaneous remission with a durable response. This case suggests that not all patients with primary CNS lymphomas require aggressive treatment with chemotherapy and radiation therapy.

Administration of nucleoside-modified mRNA encoding broadly neutralizing antibody protects humanized mice from HIV-1 challenge.

Monoclonal antibodies are one of the fastest growing classes of pharmaceutical products, however, their potential is limited by the high cost of development and manufacturing. Here we present a safe and cost-effective platform for in vivo expression of therapeutic antibodies using nucleoside-modified mRNA. To demonstrate feasibility and protective efficacy, nucleoside-modified mRNAs encoding the light and heavy chains of the broadly neutralizing anti-HIV-1 antibody VRC01 are generated and encapsulated into lipid nanoparticles. Systemic administration of 1.4 mg kg-1 of mRNA into mice results in ∼170 µg ml-1 VRC01 antibody concentrations in the plasma 24 h post injection. Weekly injections of 1 mg kg-1 of mRNA into immunodeficient mice maintain trough VRC01 levels above 40 µg ml-1. Most importantly, the translated antibody from a single injection of VRC01 mRNA protects humanized mice from intravenous HIV-1 challenge, demonstrating that nucleoside-modified mRNA represents a viable delivery platform for passive immunotherapy against HIV-1 with expansion to a variety of diseases.

Selective neutralization of the chemokine TCA3 reduces the increased injury of partial versus whole liver transplants induced by cold preservation.

BACKGROUND: Given the shortage of liver donors and the development of techniques for partial liver transplantation, we compared chemokine expression and inflammatory cell infiltration of partial versus whole grafts in a mouse syngeneic liver transplant model. METHODS: Orthotopic liver transplantation, using whole or partial murine liver grafts, was performed following cold preservation in ViaSpan solution for periods of one to eight hours. RESULTS: Partial grafts showed more severe cold ischemia/reperfusion injury and greater inflammatory cell infiltration than whole grafts, and was accompanied by the marked intrahepatic upregulation of multiple chemokines. Quantitative analysis showed that compared with expression in whole grafts harvested after the same period of cold ischemia, partial grafts had eightfold more T-cell activation gene (TCA)-3 (CCL1) chemokine messenger RNA (mRNA) expression (P<0.01) and sixfold more inducible protein (IP)-10 chemokine (CCL10) mRNA expression (P<0.01), as well as increased expression of the chemokine receptors CCR8 (receptor for TCA3) and CXCR3 (receptor for IP-10; P<0.01). Blockade of TCA3 by neutralizing monoclonal antibody significantly decreased intragraft IP-10 expression (P<0.05) but not tumor necrosis factor-alpha or interleukin-6 expression in partial grafts, and significantly decreased cold ischemia/reperfusion injury (P<0.05) and associated neutrophil and T-cell infiltration (P<0.01). CONCLUSIONS: These data demonstrate that the chemokine TCA3/CCL1 is important to the pathogenesis of ischemic injury of experimental partial liver grafts, and that its therapeutic targeting within such grafts can overcome the deleterious effects of prolonged cold preservation and restore liver function to the level achieved using whole liver grafts.

Patterns of transgene expression and viral clearance from the transplanted liver following ex vivo adenovirus-mediated gene transfer.

BACKGROUND/AIMS: In the rat liver transplant model, the liver graft can be transduced ex vivo by adenovirus encoding CTLA-4Ig (AdCTLA-4Ig) to achieve high level of immunosuppression in the liver after transplantation. To characterize the pattern of transgene expression following ex vivo gene transfer to the liver and examine whether immunosuppression would promote adenovirus persistence, we followed the life span of vector DNA and transgene expression in the transplanted liver. METHODS: Rat liver grafts were perfused ex vivo with adenovirus carrying the reporter gene beta-galactosidase (AdlacZ). The period of transgene expression was assessed at predetermined intervals after transplantation into syngeneic, allogeneic or nude (athymic) recipients. Clearance of vector DNA was assessed by PCR analysis of liver DNA after transplantation. RESULTS: Graft transduction with AdCTLA-4Ig or systemic cyclosporine treatment effectively abrogated the alloimmune response but did not result in sustained lacZ expression. The course of viral DNA clearance from the liver was also unaffected by immunosuppression as was the implied nucleolytic cleavage of viral DNA. CONCLUSIONS: In the transplant setting, local expression of CTLA-4Ig or systemic immunosuppression does not solve the problem of viral clearance from the liver. Non-adaptive immune mechanisms may have a significant role in the host response to adenovirus after liver transplantation.

Pattern of ischemia reperfusion injury in a mouse orthotopic liver transplant model.

BACKGROUND: The molecular pathways of ischemic injury after liver transplantation are complex and difficult to dissect because of the presence of many variables. Transgenic and genetically deficient strains of mice provide ideal models for the study of the contribution of a single gene product in biological processes in vivo. Although well described in rats, prolonged preservation has not been studied in a mouse model of orthotopic liver transplantation (mOLT). The aim of this study was to establish a model of cold ischemia and reperfusion injury in mOLT and describe the pattern of the regenerative response to various lengths of cold storage. MATERIALS AND METHODS: mOLT was performed using a syngeneic combination. Grafts were preserved at 4 degrees C in University of Wisconsin (Viaspan) solution for increasing periods of cold preservation. After cold storage, the liver grafts were transplanted and recipient survival was monitored. Hepatocellular injury was determined by histology, and the regenerative response was quantitated by interleukin 6 upregulation and DNA replication. RESULTS: Long-term survival was 100%, 100%, 88%, and 0% for cold preservation of 1, 4, 8, and 16 h, respectively. Grafts with short preservation times (1 and 4 h) demonstrated limited injury and a weak regenerative response, with slight IL-6 early upregulation and minimal cell division. Eight hours of cold ischemia resulted in prominent injury and an intense regenerative response accompanied by significant IL-6 upregulation and DNA synthesis. Sixteen hours of storage resulted in all recipients succumbing to liver failure, with histology showing extensive hepatic necrosis. CONCLUSIONS: This study demonstrated the feasibility of using the mOLT model for the study of molecular mechanisms associated with recovery from cold ischemia and reperfusion injury. Increasing lengths of cold ischemia correlate with progressive tissue damage whereas recovery is associated with a regenerative response that correlates with the severity of injury.

Dexamethasone inhibits early regenerative response of rat liver after cold preservation and transplantation.

Regeneration is crucial for the recovery of hepatic mass following liver transplantation. Glucocorticoids, immunosuppressive and antiinflammatory agents commonly used in transplantation, are known to inhibit the expression of specific cytokines and growth factors. Some of these proteins, namely tumor necrosis factor alpha (TNF-alpha) and interleukin 6 (IL-6), play a critical role in the initiation of liver regeneration. Following cold preservation and reperfusion of the transplanted liver, the normal recovery process is marked by increased expression of TNF-alpha and IL-6, followed by activation of cytokine-responsive transcription factors and progression of the cell cycle resulting in hepatocyte proliferation. We hypothesized that glucocorticoids may influence the repair mechanisms initiated after extended cold preservation and transplantation. Using a rat orthotopic liver transplant model, recipient animals were treated with dexamethasone at the time of transplantation of liver grafts with prolonged cold storage (16 hours). Treatment with dexamethasone suppressed and delayed the expression of TNF-alpha and IL-6 compared with animals receiving no treatment and attenuated downstream nuclear factor kappaB (NF-kappaB), signal transduction and activator of transcription 3 (STAT3), and activation protein 1 (AP-1) activation. This suppression was accompanied by poor cell-cycle progression, delayed cyclin D1 nuclear transposition, and impaired hepatocyte proliferation by BrdU uptake. Histologically, the liver grafts in treated animals demonstrated more injury than controls, which appeared to be necrosis, rather than apoptosis. In conclusion, these data provide evidence that the administration of glucocorticoids at the time of transplantation inhibits the initiation of the regenerative process and may have a deleterious effect on the recovery of liver grafts requiring significant regeneration. This may be particularly relevant for transplantation of partial liver grafts in the living donor setting.

Severe preservation injury induces Il-6/STAT3 activation with lack of cell cycle progression after partial liver graft transplantation.

Partial liver graft transplantation is a surgical advance developed to overcome severe donor shortage. Survival of these grafts involves recovery from cold ischemia and reperfusion (CIR) injury, immediate regeneration and maintenance of function. Here we examined the outcome of partial liver grafts in comparison to whole grafts following CIR injury. Lewis rats subjected to orthotopic liver transplantation (OLT) with whole grafts preserved in Viaspan were compared to rats receiving 50% and 30% grafts. Outcome was analyzed by survival and regeneration. Transplantation was associated with 100% survival for all grafts, whereas 16 h preservation resulted in 100%, 20% and 0% survival in animals receiving whole, 50% and 30% grafts, respectively. CIR induced increased IL-6 levels in 50% and 30% grafts, and activation of STAT3. Cell cycle progression (cyclin D1) and regeneration (BrdU) was initiated in all livers preserved for 1 or 8 h, but not in partial grafts preserved for 16 h. In conclusion, partial grafts recover from CIR injury through similar molecular pathways to whole grafts. Partial grafts with severe injury fail to achieve cellular proliferation despite the early initiating signals. This failure could be attributed to the impaired ability of the parenchyma to respond to initiating signals for regeneration.

Interleukin-6 from intrahepatic cells of bone marrow origin is required for normal murine liver regeneration.

Interleukin-6 (IL-6) is required for normal liver regeneration, but the specific cellular source of this growth factor is unknown. We investigated whether this signal originates from the resident macrophage, the Kupffer cell. Using a murine model of bone marrow transplantation, we replaced recipient bone marrow-derived cells, including Kupffer cells, with cells of donor genetic phenotype. Recipients deficient in IL-6 (IL-6(-/-)) were lethally irradiated, then rescued with 10(7) donor bone marrow cells capable of expressing IL-6 (IL-6(+/+)). Conversely, IL-6(+/+) recipients received IL-6(-/-) marrow. Successful engraftment was measured by the presence of the Y chromosome SRY locus in the livers of female recipients receiving male marrow, in situ IL-6 expression by Kupffer cells, and up-regulation of IL-6 in splenocytes after activation with lipopolysaccharide (LPS). Kupffer cell isolation in IL-6(-/-) females receiving IL-6(+/+) male marrow clearly showed the presence of the SRY locus and IL-6 disrupted allele, whereas males receiving female marrow demonstrated no SRY or IL-6 signals, confirming the extent of replacement. Replacement of these cells in IL-6(-/-) mice with IL-6(+/+) bone marrow successfully restored the regenerative response after partial hepatectomy (PHx) as indicated by signal transduction and activator of transcription 3 (STAT3) activation and hepatocyte DNA replication. Alternatively, complete replacement of Kupffer cells in IL-6(+/+) mice by transplantation with IL-6(-/-) cells significantly inhibited liver regeneration and was partially restored by administration of IL-6. This investigation demonstrates a paracrine mechanism by which cells of bone marrow origin, most likely Kupffer cells, regulate the regenerative capacity of the hepatocyte through IL-6 expression.