Regulatory T cells that co-express RORγt and FOXP3 are pro-inflammatory and immunosuppressive and expand in human pancreatic cancer.

Pancreatic ductal adenocarcinoma (PDAC) is highly infiltrated by CD4+T cells that express RORγt and IL-17 (TH17). Compelling evidence from the tumor microenvironment suggest that regulatory T cells (Treg) contribute to TH17 mediated inflammation. Concurrently, PDAC patients have elevated levels of pro-inflammatory cytokines that may lead to TH17 associated functional plasticity in Treg. In this study, we investigated the phenotype and functional properties of Treg in patients with PDAC. We report that PDAC patients have elevated frequency of FOXP3+Treg, which exclusively occurred within the FOXP3+RORγt+Treg compartment. The FOXP3+RORγt+Treg retained FOXP3+Treg markers and represented an activated subset. The expression of RORγt in Treg may indicate a phenotypic switch toward TH17 cells. However, the FOXP3+RORγt+Treg produced both TH17 and TH2 associated pro-inflammatory cytokines, which corresponded with elevated TH17 and TH2 immune responses in PDAC patients. Both the FOXP3+Treg and FOXP3+RORγt+Treg from PDAC patients strongly suppressed T cell immune responses, but they had impaired anti-inflammatory properties. We conclude that FOXP3+RORγt+Treg have a dual phenotype with combined pro-inflammatory and immunosuppressive activity, which may be involved in the pathogenesis of PDAC.

Human regulatory T cells control TCR signaling and susceptibility to suppression in CD4+ T cells.

Human CD4(+)CD25(hi)FOXP3(+) regulatory T cells maintain immunologic tolerance and prevent autoimmune and inflammatory immune responses. Regulatory T cells undergo a similar activation cycle as conventional CD4(+) T cells upon antigen stimulation. Here, we demonstrate that T cell receptors and costimulation are required to activate the regulatory T cell suppressive function. Regulatory T cells suppressed the T cell receptor signaling in effector T cells in a time-dependent manner that corresponded with inhibition of cytokine production and proliferation. Modulation of the activation level and thereby the suppressive capacity of regulatory T cells imposed distinct T cell receptor signaling signatures and hyporesponsiveness in suppressed and proliferating effector T cells and established a threshold for effector T cell proliferation. The immune suppression of effector T cells was completely reversible upon removal of regulatory T cells. However, the strength of prior immune suppression by regulatory T cells and corresponding T cell receptor signaling in effector T cells determined the susceptibility to suppression upon later reexposure to regulatory T cells. These findings demonstrate how the strength of the regulatory T cell suppressive function determines intracellular signaling, immune responsiveness, and the later susceptibility of effector T cells to immune suppression and contribute to unveiling the complex interactions between regulatory T cells and effector T cells.

Indications and Outcomes in Liver Transplantation in Patients With Primary Sclerosing Cholangitis in Norway.

BACKGROUND: Primary sclerosing cholangitis (PSC) is 1 of the leading causes of liver transplantation (LTX) in Scandinavia, and an increasing number of PSC patients have been transplanted in Norway during the last 2 decades. This trend is partly attributable to the recently established practice in Norway of offering LTX to PSC patients with cholangiocellular dysplasia. Based on the controversy associated with this practice, we herein aimed to report the main features and outcomes of our LTX program in PSC. METHODS: The primary indication for LTX (quality of life/end-stage liver disease or suspected neoplasia) was retrospectively determined for 222 patients undergoing LTX for PSC or other autoimmune liver diseases (primary biliary cirrhosis/autoimmune hepatitis) with at least 5 years of follow-up. RESULTS: In PSC patients impaired quality of life (43.5%) and end-stage liver disease (38.4%) were the most frequent indications for LTX, whereas suspected neoplasia accounted for 18.1%. The proportion of PSC patients with manifest encephalopathy, variceal bleeding, or ascites declined over time. In patients with suspected neoplasia as the primary indication for LTX (n = 25), neoplasia was confirmed in the explanted liver in 20 patients (80%). Five-year survival rates for PSC patients transplanted between 2001 and 2009 were 91.9% for patients receiving LTX due to impaired quality of life or end-stage liver disease and 83.3% for suspected neoplasia. CONCLUSIONS: The PSC patients are increasingly listed for LTX at an earlier stage of their liver disease. In patients with suspected neoplasia before LTX, 5-year survival was acceptable, despite confirmation of neoplasia in 80% of the liver explants.

Mycophenolate pharmacokinetics and inosine monophosphate dehydrogenase activity in liver transplant recipients with an emphasis on therapeutic drug monitoring.

BACKGROUND: The pharmacokinetics of the immunosuppressant mycophenolic acid (MPA) demonstrates high inter- and intra-patient variability. Variation in the binding of MPA to albumin has been postulated to be an important factor in this variability, and monitoring of free MPA has been suggested to improve therapeutic drug monitoring (TDM) of MPA. Inosine monophosphate dehydrogenase (IMPDH) is the target enzyme for MPA, therefore the IMPDH activity in lymphocytes can serve as a marker of the MPA-specific response. This study aimed to explore how the albumin concentration influences the free concentration of MPA in liver transplant recipients and to assess whether alteration in the free MPA influences IMPDH activity in CD4 + cells. METHODS: Blood samples were taken from 20 liver transplant recipients on two separate occasions (days 3-5 and 16-21). Total and free concentrations of MPA, and IMPDH activity were measured during the first 4 h of each dose interval. RESULTS: Albumin levels correlated with the free fraction of MPA. However, the total MPA and free MPA were equal predictors of the immunosuppressive response as defined by IMPDH activity. CONCLUSION: Total and free MPA are equally good predictors of the immunosuppressive effect exerted by MPA as defined by IMPDH activity. IMPDH activity measurements represent a promising approach to TDM in patients treated with MPA.

Expression of IMPDH1 and IMPDH2 after transplantation and initiation of immunosuppression.

BACKGROUND: Mycophenolic acid (MPA) mediates immunosuppressive effects by inhibiting inosine monophosphate dehydrogenase (IMPDH). Induction of IMPDH activity has been observed in whole blood and erythrocyte samples during immunosuppressive therapy. Information concerning the mechanisms for increased IMPDH activity is limited and the potential implications of induction have been debated. METHODS: Whole blood, CD4+ cell, and reticulocyte samples were collected from 30 renal transplant patients pre- and posttransplantation. The expressions of two IMPDH isoforms, type 1 and 2, were analyzed by real-time reverse-transcription polymerase chain reaction and quantified using a housekeeping gene index. The IMPDH activity was determined by ultraviolet high-performance liquid chromatography. RESULTS: Transplantation and the initiation of immunosuppressive therapy was associated with increased IMPDH1 (50-88%, P<0.0005) and decreased IMPDH2 (42-56%, P<0.0005) expression. In CD4+ cells, however, IMPDH2 increased (15%, P=0.009). These changes are probably related to glucocorticoid effects. Two weeks posttransplant, MPA-treated patients displayed elevated IMPDH 1 and 2 in reticulocytes, suggesting enzyme induction in these cells during prolonged MPA therapy. Patients with acute rejection during follow-up demonstrated higher IMPDH2 expression in CD4+ cells pretransplant than nonrejecting patients (median expression 1.26 vs. 0.87 respectively, P=0.017). CONCLUSIONS: Knowledge of changes in IMPDH 1 and 2 expression after transplantation and initiation of immunosuppression is important considering the action of MPA on IMPDH and the potential for pharmacodynamic monitoring of MPA by measuring IMPDH activity. The expression of IMPDH2 in CD4+ cells pretransplant may be an indicator of immune activation.

Calcineurin inhibitor avoidance with daclizumab, mycophenolate mofetil, and prednisolone in DR-matched de novo kidney transplant recipients.

BACKGROUND: Calcineurin inhibitor (CNI)-free regimens posttransplantation have been claimed to conserve graft function in addition to reduce the risk factors for cardiovascular and malignant disease in renal transplant recipients. METHODS: The primary aim of this prospective, open-label, randomized, parallel-group, single-center study was to compare the effect of complete CNI-avoidance posttransplant (daclizumab + mycophenolate mofetil + prednisolone: Dac-group, n=27) with the standard CNI-based immunosuppressive protocol at our transplant unit (cyclosporine A + mycophenolate mofetil + prednisolone: CsA-group, n=27) on renal function (glomerular filtration rate [GFR] determined as plasma clearance of 51Cr-EDTA) in a selected low immunogenic risk population (DR-matched, PRA-negative de novo cadaveric transplant recipients). RESULTS: There were no significant difference in GFR at week 10 (P=0.61), but GFR was significantly (P=0.029) lower in the Dac-group (52+/-20 ml/min) at month 12 than in the CsA-group (69+/-29 ml/min). One-year patient and graft survival did not differ between the two groups. Overall acute rejection rate was 70.4% (19/27) in the Dac-group and 29.6% (8/27) in the CsA-group (P=0.006). CONCLUSIONS: The strategy to select DR-matched, PRA-negative de novo cadaveric transplant recipients for a CNI-avoidance protocol was not successful. The incidence of acute rejection was unacceptable high even though anti-CD25 antibody induction as well as initial higher mycophenolate mofetil doses (3 g/day) were applied, and renal function was significantly lower in the CNI-avoidance patients at 1 year. Other strategies need to be examined for avoidance of CNI's in the early posttransplant period.