Previous evidence suggests that a homeostatic germinal center (GC) response may limit bortezomib desensitization therapy. We evaluated the combination of costimulation blockade with bortezomib in a sensitized non-human primate kidney transplant model. Sensitized animals were treated with bortezomib, belatacept, and anti-CD40 mAb twice weekly for a month (n = 6) and compared to control animals (n = 7). Desensitization therapy-mediated DSA reductions approached statistical significance (P = .07) and significantly diminished bone marrow PCs, lymph node follicular helper T cells, and memory B cell proliferation. Graft survival was prolonged in the desensitization group (P = .073). All control animals (n = 6) experienced graft loss due to antibody-mediated rejection (AMR) after kidney transplantation, compared to one desensitized animal (1/5). Overall, histological AMR scores were significantly lower in the treatment group (n = 5) compared to control (P = .020). However, CMV disease was common in the desensitized group (3/5). Desensitized animals were sacrificed after long-term follow-up with functioning grafts. Dual targeting of both plasma cells and upstream GC responses successfully prolongs graft survival in a sensitized NHP model despite significant infectious complications and drug toxicity. Further work is planned to dissect underlying mechanisms, and explore safety concerns.

The efficacy of bortezomib monotherapy in desensitizing kidney transplant candidates with preformed donor-specific antibodies remains unclear. We evaluated the effect of bortezomib on preformed antibodies and upstream components of the B cell response in a primate model sensitized by fully mismatched allogeneic skin transplants to provide mechanistic insights regarding the use of bortezomib as a means of desensitization. Bortezomib treatment given intravenously twice weekly for 1 month (1.3 mg/m per dose) clearly reduced the numbers of antibody-producing cells and CD38CD19CD20 plasma cells in the bone marrow (<0.05), but donor-specific alloantibody levels did not decrease. We observed a rapid but transient induction of circulating IgG B cells and an increased number of proliferating B cells in the lymph nodes after 1 month of treatment. Notably, bortezomib treatment induced germinal center B cell and follicular helper T cell expansion in the lymph nodes. These data suggest that bortezomib-induced plasma cell depletion triggers humoral compensation.

We have established a model of sensitization in non-human primates and tested two immunosuppressive regimens. Animals underwent fully mismatched skin transplantation, donor-specific antibody (DSA) response was monitored by flow crossmatch. Sensitized animals subsequently underwent kidney transplantation from their skin donor. Immunosuppression included tacrolimus, mycophenolate and methylprednisolone. Three animals received basiliximab induction, compared to non-sensitized animals they showed a shorter mean survival time (MST, 4.7±3.1 vs. 187±88 days). Six animals were treated with T-cell depletion (anti-CD4/CD8 mAbs), which prolonged survival (MST=21.6±19.0 days). All pre-sensitized animals showed antibody-mediated rejection (AMR). In 2/3 basiliximab animals cellular rejection (ACR) was prominent. After T cell depletion, 3/6 monkeys experienced early acute rejection within 8 days with histological evidence of thrombotic microangiopathy and AMR. The remaining three survived 27 to 44 days, with mixed AMR and ACR. Most T-cell depleted animals experienced a rebound of DSA that correlated with deteriorating kidney function. We also found an increase in proliferating memory B cells (CD20+CD27+IgD−Ki67+), lymph node follicular helper T cells (ICOS+PD-1hiCXCR5+CD4+) and germinal center response. Depletion controlled cell-mediated rejection in sensitized non-human primates better than basiliximab, yet grafts were rejected with concomitant DSA rise. This model provides an opportunity to test novel desensitization strategies.

Austrian Science Fund and Austrian Academy of Science.

The appropriate time point for starting immunosuppressive treatment with calcineurin inhibitors after orthotopic liver transplantation (OLT) has been a subject of debate. The aim of the study was to analyze the effects of anti-thymocyte globulin (ATG) induction therapy on rejection, renal function, infection, tumor rate, and survival. We retrospectively analyzed 391 patients after OLT who had either received calcineurin inhibitors immediately after OLT (n ϭ 129) or after an initial short-term Thymoglobulin induction therapy (n ϭ 262). The 1-year acute rejection rate was 14.5% vs. 31.8% in favor of ATG (P ϭ 0.0008). Rejection grades and the need for treatment also differed significantly (7.3% vs. 23.3%; P ϭ 0.001). Serum creatinine at transplantation was similar in both groups (1.14 mg/dL vs.1.18 mg/dL; P ϭ NS). Postoperative hemofiltration was less frequently seen after induction therapy (P Ͻ 0.05). Reduced renal function at 1 year was commonly observed, but serum creatinine (1.26 mg/dL vs. 1.37mg/dL; P ϭ 0.015) and glomerular filtration rate (81 mL/min vs. 75 mL/min; P ϭ 0.02) were far better in the ATG group. Undesired side effects occurred at a similar rate in both groups. Five-year patient survival was also similar in the 2 groups (70.1% and 74.3%; P Ͼ 0.05). Short-term ATG induction therapy with delayed administration of calcineurin inhibitors led to a more favorable rejection rate and an improved clinical course in case of a rejection episode. It has beneficial effects on renal function immediately after OLT as well as later, and no additional harmful effects. Liver Transpl 13: [1039][1040][1041][1042][1043][1044] 2007. © 2007 AASLD.Received October 12, 2006; accepted March 8, 2007. It took nearly 20 years for orthotopic liver transplantation (OLT) to develop into a widely used standard procedure for patients with end-stage liver disease. One of the essential aspects of this development was the introduction of cyclosporine A (CyA) in clinical immunosuppression. CyA led to far lower rejection rates than those achieved with any other drug known at the time. Several immunosuppressive agents have been developed since and are used in various regimens with calcineurin inhibitors (e.g., CyA and tacrolimus). Immunosuppressants are a fundamental aspect of nearly all treatment protocols for OLT. 1 However, for more then 40 years, debate has existed regarding when immunosuppression in OLT should be initiated and what treatment should be used. The spectrum ranges from nearly all kinds of T cell-depleting antibodies and interleukin-2 receptor antibodies to simply providing no specific induction therapy, and the use of the same regimen when maintenance therapy is started. [2][3][4] The purpose of all immunosuppressive regimens is to achieve low rejection rates on the one hand and a favorable side effect profile on the other.

Cross-talk between B and T cells in transplantation is increasingly recognized as being important in the alloimmune response. T cell activation of B cells occurs by a 3-stage pathway, culminating with costimulation signals. We review the distinct T cell subtypes required for B cell activation, and discuss the formation of the Germinal Center (GC) after transplantation, with particular reference to the repopulation of the GC following depletional induction, and the subsequent effect of immunosuppressive manipulation of T-B cell interactions. Additionally, ectopic GCs are seen in transplantation, but their role is not fully understood. Therapeutic options to target T-B cell interactions are of considerable interest, both as immunosuppressive tools, and to aid further understanding of these important alloimmune mechanisms.

Background:Despite the widespread use of neoadjuvant chemotherapy in breast cancer patients, prediction of individual response to treatment remains an unsolved clinical problem. Particularly, administration of an inefficient chemotherapeutic regimen should be avoided. Therefore, a better understanding of the molecular mechanisms underlying response to neoadjuvant chemotherapy is of particular clinical interest. Aim of the present study was to test whether neoadjuvant chemotherapy with epirubicin/docetaxel induces early changes in the plasma proteome of breast cancer patients and whether such changes correlate with response to therapy.Methods:Plasma samples of 25 breast cancer patients obtained before and 24 h after initiation of epirubicin/docetaxel-based neoadjuvant chemotherapy were analysed using two-dimensional differential gel electrophoresis (2D-DIGE). Protein spots found to be differentially expressed were identified using mass spectrometry and then correlated with the pathological response after six cycles of therapy. Markers identified in a discovery set of patients (n=12) were confirmed in an independent validation set (n=13).Results:2D-DIGE revealed 33 protein spots to be differentially expressed in response to chemotherapy, including the complement factors C1, C3 and C4, inter-α-trypsin inhibitor, α-1-antichymotrypsin and α-2-Heremans-Schmid glycoprotein (AHSG). With respect to cytokines, only interleukin (IL)-6, IL-10 and soluble intracellular adgesion molecule 3 (sICAM3) were minimally modulated. Moreover, two protein spots within the complement component C3 significantly correlated with response to therapy.Conclusion:We have identified acute phase proteins and the complement system as part of the early host response to epirubicin/docetaxel chemotherapy. As complement C3 cleavage correlates with the efficacy of docetaxel/epirubicin-based chemotherapy, it has the potential as an easily accessible predictive biomarker.

Our data suggest that early dynamic changes of plasma HMGB1 could be a promising biomarker to predict the final response to NCT in breast cancer patients.