Addition of Anti-CD40 Monoclonal Antibody to Nonmyeloablative Conditioning With Belatacept Abrogated Allograft Tolerance Despite Induction of Mixed Chimerism.

BACKGROUND: We recently reported anti-CD40 monoclonal antibody and rapamycin (aCD40/rapa) to be a reliable, nontoxic, immunosuppressive regimen for combined islet and kidney transplantation (CIKTx) in nonhuman primates. In the current study, we attempted to induce allograft tolerance through the mixed chimerism approach using a conditioning regimen with aCD40 and belatacept (Bela). METHODS: Five CIKTx or kidney transplant alone recipients were treated with aCD40/rapa for 4 months. All recipients then received a conditioning regimen including horse antithymocyte globulin and aCD40/Bela. The results were compared with previous reports of recipients treated with Bela-based regimens. RESULTS: All 3 CIKTx recipients developed mixed chimerism, which was significantly superior to that observed in the previous Bela-based studies. Nevertheless, all CIKTx recipients in this study lost their islet and renal allografts as a result of cellular and humoral rejection on days 140, 89, and 84. The 2 kidney transplant-alone recipients were treated with the same conditioning regimen and suffered rejection on days 127 and 116, despite the development of excellent chimerism. B lymphocyte reconstitution dominated by memory phenotypes was associated with early development of donor-specific antibodies in 4 of 5 recipients. In vitro assays showed no donor-specific regulatory T cell expansion, which has been consistently observed in tolerant recipients with our mixed chimerism approach. CONCLUSIONS: Despite displaying excellent immunosuppressive efficacy, costimulatory blockade with anti-CD40 monoclonal antibody (2C10R4) may inhibit the induction of renal or islet allograft tolerance via a mixed chimerism approach.

Prophylactic orthosteric inhibition of leukocyte integrin CD11b/CD18 prevents long-term fibrotic kidney failure in cynomolgus monkeys.

Ischaemic acute kidney injury (AKI), an inflammatory disease process, often progresses to chronic kidney disease (CKD), with no available effective prophylaxis. This is in part due to lack of clinically relevant CKD models in non-human primates. Here we demonstrate that inhibition of the archetypal innate immune receptor CD11b/CD18 prevents progression of AKI to CKD in cynomolgus monkeys. Severe ischaemia-reperfusion injury of the right kidney, with subsequent periods of the left ureter ligation, causes irreversible right kidney failure 3, 6 or 9 months after AKI. Moreover, prophylactic inactivation of CD11b/CD18, using the orthosteric CD11b/CD18 inhibitor mAb107, improves microvascular perfusion and histopathology, reduces intrarenal pro-inflammatory mediators and salvages kidney function long term. These studies reveal an important early role of CD11b+ leukocytes in post-ischaemic kidney fibrosis and failure, and suggest a potential early therapeutic intervention to mitigate progression of ischaemic AKI to CKD in humans.

Dendritic cell maturation occurs through the inhibition of GSK-3ß.

Dendritic cell (DC) maturation results in changes in antigen processing and presentation, governing the fate of adaptive immunity. Understanding the intracellular signaling pathways governing DC maturation is therefore critical. In this study, we observed that the kinase, GSK-3ß, is present in its active form in resting immature DCs isolated from the spleen and bone marrow of mice. Induction of DC maturation using GM-CSF, IL-4 and TNF-α resulted in GSK-3ß inhibition, as reflected by increased phosphorylation of Serine 9 on the kinase, and concomitant stabilization of its substrate, ß-catenin. Treatment of immature DCs with a GSK-3ß inhibitor increased cell surface expression of CD80, CD86 and CD40 on DCs, enhancing their ability to present antigen and activating IL-2 secretion by T cells. GSK-3ß inhibition also parallels dendritic cell maturation in vivo. Our results show that GSK-3ß signaling controls DC maturation and suggest that this kinase could be manipulated to modulate adaptive immunity.

Induction of tolerance in clinical kidney transplantation.

Induction of donor-specific tolerance has been an ultimate goal in organ transplantation. Although numerous regimens for the induction of allograft tolerance have been developed in rodents, their application to primates has been limited. The approaches that have been successfully applied in primates can be divided into (i) use of total lymphoid irradiation, (ii) costimulatory blockade, (iii) profound depletion of recipient T cells, (iv) infusion of regulatory cells and (v) donor bone marrow (DBM) infusion/transplantation. Among these approaches, successful allograft tolerance has been achieved in clinical kidney transplantation using DBM transplantation.

Pathological and clinical correlates of FOXP3+ cells in renal allografts during acute rejection.

The localization and significance of regulatory T cells (Treg) in allograft rejection is of considerable clinical and immunological interest. We analyzed 80 human renal transplant biopsies (including seven donor biopsies) with a double immunohistochemical marker for the Treg transcription factor FOXP3, combined with a second marker for CD4 or CD8. Quantitative FOXP3 cell counts were performed and analyzed for clinical and pathologic correlates. FOXP3(+) cells were present in the interstitium in acute cellular rejection (ACR) type I and II, at a greater density than in acute humoral rejection or CNI toxicity (p < 0.01). Most FOXP3(+) cells were CD4(+) (96%); a minority expressed CD8. FOXP3(+)CD4(+) cells were concentrated in the tubules (p < 0.001), suggesting a selective attraction or generation at that site. Considering only patients with ACR, a higher density of FOXP3(+) correlated with HLA class II match (p = 0.03), but paradoxically with worse graft survival. We conclude that infiltration of FOXP3(+) cells occurs in ACR to a greater degree than in humoral rejection, however, within the ACR group, no beneficial effect on outcome was evident. Tregs concentrate in tubules, probably contributing to FOXP3 mRNA in urine; the significance and pathogenesis of 'Treg tubulitis' remains to be determined.

Pegylated interferon alpha-2b plus ribavirin in the treatment of post-liver transplant recurrent hepatitis C.

BACKGROUND: Histological recurrence of the hepatitis C virus (HCV) occurs in the majority of persons transplanted for cirrhosis as a result of HCV. Herein we analyze our experience with the use of both conventional and pegylated (PEG) interferon (IFN) in combination with ribavirin (RBV) in liver transplant recipients with recurrent HCV. METHODS: Patients transplanted between 1992 and 2001 with post-orthotopic liver transplantation (OLT) histological recurrence of HCV, and who were treated with at least 6 months of IFN or PEG-IFN in combination with RBV were included in this analysis. A retrospective chart review was performed. RESULTS: A total of 31 patients were included. Fifteen were treated with IFN/RBV and 16 with PEG-IFN/RBV. Of these 16, 11 had been begun on IFN/RBV and were changed to PEG-IFN/RBV because of persistent viremia. Three patients (20%) in the IFN/RBV group and six patients (37.5%) in the PEG-IFN/RBV group experienced a virologic response (VR) on therapy. Of the six patients experiencing VR in the PEG-IFN/RBV group, three (50%) were IFN/RBV non-responders. There were two sustained VRs (SVR). The 65.6% of all patients experienced a biochemical response (BR) on therapy. Seven deaths were observed. Dose modifications of IFN or PEG-IFN (87.1%) and RBV (80.6%) and the requirement for hematopoietic growth factors were frequent. CONCLUSIONS: Treatment of recurrent HCV infection with combination of IFN or PEG-IFN and RBV produced an on-therapy VR in 29% and BR in 65% of patients. Hematologic toxicity and dose modifications were frequent. Our experience with antiviral therapy for HCV post-OLT remains disappointing but PEG-IFN + RBV appears to produce VR in a sizable portion of IFN + RBV non-responders.