Cytokine profiles in early rejection following OKT3 treatment in liver transplant patients

Cytokines in Liver Transplantation

Cytokines, soluble mediators of the immune system, play a critical role in the pathogenesis of autoimmune, allergic and infectious diseases. They are also implicated in the initiation and development of allograft rejection. During recent years, there have been considerable advances in generating novel anti-cytokine agents with promoted efficacy and safety, which could be administrated for managing dysregulated cytokine secretion; besides, gene therapy for overexpression of immunomodulatory cytokines has shown substantial improvements. Liver transplantation has been established as a life-saving treatment for end-stage hepatic diseases but the growing number of recipients urge for improved post-transplant care including tolerance induction, infection control and resolving immunosuppressant drugs adverse effects. Cytokines with a wide range of proinflammatory and regulatory properties might be considered as potential therapeutic targets for selective suppression or enhancement of the immune responses in recipients. In the present review, we aimed to summarize the positive and negative effects of cytokines on liver allograft in addition to their prognostic and therapeutic values.

Humanized Mouse as a Tool to Predict Immunotoxicity of Human Biologics

Advancements in science enable researchers to constantly innovate and create novel biologics. However, the use of non-human animal models during the development of biologics impedes identification of precise in vivo interactions between the human immune system and treatments. Due to lack of this understanding, adverse effects are frequently observed in healthy volunteers and patients exposed to potential biologics during clinical trials. In this study, we evaluated and compared the effects of known immunotoxic biologics, Proleukin^®/IL-2 and OKT3 in humanized mice (reconstituted with human fetal cells) to published clinical outcomes. We demonstrated that humanized mice were able to recapitulate in vivo pathological changes and human-specific immune responses, such as elevated cytokine levels and modulated lymphocytes and myeloid subsets. Given the high similarities of immunological side effects observed between humanized mice and clinical studies, this model could be used to assess immunotoxicity of biologics at a pre-clinical stage, without placing research participants and/or patients at risk.

Cytomegalovirus infection in renal transplantation: clinical aspects, management and the perspectives

Cytomegalovirus infection is one of most frequent infectious complications after renal transplantation, and can be classified as primo-infection, when the transmission occurs through the graft, or reactivation, when the recipient is cytomegalovirus seropositive. After transplantation, cytomegalovirus can appear as an infection, when the patient presents with evidence of viral replication without symptoms or disease, which has two clinical spectra: typical viral syndrome or invasive disease, which is a less common form. Their effects can be classified as direct, while the disease is developed, or indirect, with an increase of acute rejection and chronic allograft dysfunction risks. Diagnosis must be made based on viremia by one of the standardized methods: antigenemia or PCR, which is more sensitive. The risk factors related to infection after transplantation are the serologic matching (positive donor and negative recipient) and anti-lymphocyte antibody drugs. One of the strategies to reduce risk of disease should be chosen for patients at high risk: preemptive treatment or universal prophylaxis. Recent clinical research has described ganciclovir resistance as an emergent problem in management of cytomegalovirus infection. Two types of mutation that cause resistance were described: UL97 (most frequent) and UL54. Today, sophisticated methods of immunologic monitoring to detect specific T-cell clones against cytomegalovirus are used in clinical practice to improve the management of high-risk patients after renal transplantation.

Prolonged lymphopenia following anti-thymocyte globulin induction is associated with decreased long-term graft survival in liver transplant recipients

BACKGROUND AND AIM

Induction with anti-thymocyte globulin (ATG) during solid organ transplantation is associated with an improved clinical course and leads to prolonged lymphopenia. This study aims to investigate whether prolonged lymphopenia, caused by ATG induction, has an impact on patient and graft survival following liver and kidney transplantation.

PATIENTS AND METHODS

This was a single-center, retrospective study. A total of 292 liver and 417 kidney transplants were performed with ATG induction (6 mg/kgr, divided into four doses), and the transplant recipients were followed for at least three months. The average lymphocyte count for the first 30 days after the operation was calculated, and the cut-off value for defining lymphopenia was arbitrarily set to ≤ 500 cells/mm(3).

RESULTS

There were 210 liver transplant recipients (71.9%) who achieved prolonged lymphopenia, whereas the remaining 82 recipients (28.1%) did not. The mean survival time of these patient groups was 10.27 and 12.71 years, respectively (p = 0.1217), and the mean graft survival time was 8.98 and 12.25 years, respectively (p = 0.0147). Of the kidney transplant patients, 330 (79.1%) recipients achieved prolonged lymphopenia, whereas the remaining 87 (20.9%) did not. The mean survival time of these patient groups was 13.94 and 14.59 years, respectively, (p = 0.4490), and the mean graft survival time was 11.84 and 11.54 years, respectively (p = 0.7410).

CONCLUSION

The efficacy and safety of ATG induction partially depend on decreased total lymphocyte counts. Following ATG induction in liver transplant recipients, a reasonable average lymphocyte count during the first postoperative month would be above 500 cells/mm(3).

Regulation of hepatocyte fate by interferon-γ

Interferon (IFN)-γ is a cytokine known for its immunomodulatory and anti-proliferative action. In the liver, IFN-γ can induce hepatocyte apoptosis or inhibit hepatocyte cell cycle progression. This article reviews recent mechanistic reports that describe how IFN-γ may direct the fate of hepatocytes either towards apoptosis or a cell cycle arrest. This review also describes a probable role for IFN-γ in modulating hepatocyte fate during liver regeneration, transplantation, hepatitis, fibrosis and hepatocellular carcinoma, and highlights promising areas of research that may lead to the development of IFN-γ as a therapy to enhance recovery from liver disease.

Immunosuppressive activity of serum taken from a liver transplant recipient after withdrawal of immunosuppressants

In orthotopic liver transplantation (OLT), tolerance is induced in a certain combination of donors and a recipient in rats and, in some clinical cases, rejection has not occurred in OLT patients after weaning off immunosuppression. However, this mechanism has not yet been elucidated. Among our cases of liver transplantation (LTx), one OLT patient (Patient A) has not required immunosuppressive drugs for the last 5 years, following post-transplant lymphoproliferative disease (PTLD). This patient's serum interleukin-2 levels were undetectable following withdrawal of immunosuppressants. The same serum taken after discontinuing the immunosuppressants inhibited concanavalin A blast cultured cells and up-regulated the IL-4/IFN-gamma gene expression ratio. These results suggested that other proteins were induced following withdrawal of immunosuppressants. Proteomic assay demonstrated 12 differentiated spots exclusive to this patient where immunosuppressants have been discontinued. Haptoglobin, found to have immunosuppressive activity in vitro, may play an important role in the maintenance of drug-free tolerance as a natural immunological suppressor after cessation of immunosuppression. Proteomic analysis will allow us to develop a novel weaning protocol for patients on long-term immunosuppression to avoid major immunosuppressant-related complications.

Influence of interleukin-1alpha and tumor necrosis factor-alpha production on corneal graft survival

AIM

To determine pro-inflammatory cytokine secretion from human corneas with different pathology and to establish whether cytokine profile influences corneal graft outcome.

METHOD

Secretion of both proinflammatory cytokine interleukin (IL)-1alpha and tumor necrosis factor (TNF)-alpha was measured after cultivation of 47 corneas collected from corneal graft recipients suffering from different corneal diseases. Non-inflammatory corneal diseases were keratoconus (n=8), keratoglobus (n=2), bullous keratopathy (n=11), and Groenouw stromal dystrophy type II (n=2), whereas inflammatory included vascularized corneal scar (n=14), rejected graft (n=6), and corneal ulcer (n=4). Corneas were cultivated at 37 degrees C for 24 hours and frozen until cytokine detection was measured by immunoassay. Donor corneas unsuitable for transplantation were used as controls (n=7). Corneal graft recipients were followed at least 18 months and rejection rate was calculated for each group.

RESULTS

The median concentration of IL-1alpha secreted from corneas of recipients with non-inflammatory diseases was 2.47 pg/mm(3) (range, 0.13-9.95). In inflammatory corneal diseases, IL-1alpha concentration was significantly higher (median, 5.92 pg/mm(3); range, 0.48-12.68; P=0.005). IL-1alpha production in controls (median, 0.63 pg/mm3; range, 0.36-1.29 pg/mm(3)) was significantly lower than in inflammatory corneal diseases (P<0.001) and non-inflammatory diseases (P=0.008). Low level of TNF-alpha was detected only in 5 cases of vascularized corneal scars, 3 cases of bullous keratopathy, and 3 cases of graft rejection. Rejection rate was significantly higher in inflammatory than in non-inflammatory group (46% vs <10%, respectively, P=0.008). IL-1alpha and TNF-alpha were absent from all patient's sera, confirming its local intra-ocular production.

CONCLUSION

Increased production of IL-1alpha in corneal recipients with inflammatory diseases suggests its role in corneal graft rejection in humans.

Viral infection in the renal transplant recipient

Viruses are among the most common causes of opportunistic infection after transplantation and the most important. The risk for viral infection is a function of the specific virus encountered, the intensity of immune suppression used to prevent graft rejection, and other host factors governing susceptibility. Viral infection, both symptomatic and asymptomatic, causes the "direct effects" of invasive disease and "indirect effects," including immune suppression predisposing to other opportunistic infections and oncogenesis. Rapid and sensitive microbiologic assays for many of the common viruses after transplantation have replaced, for the most part, serologic testing and in vitro cultures for the diagnosis of infection. Furthermore, quantitative molecular tests allow the individualization of antiviral therapies for prevention and treatment of infection. This advance is most prominent in the management of cytomegalovirus, Epstein-Barr, hepatitis B, and hepatitis C viruses. Diagnostic advances have not been accompanied by the development of specific and nontoxic anti-viral agents or effective antiviral vaccines. Vaccines, where available, should be given to patients as early as possible and well in advance of transplantation to optimize the immune response. Studies of viral latency, reactivation, and the cellular effects of viral infection will provide clues for future strategies in prevention and treatment of viral infections.