Chimerism after Liver Transplantation for Type IV Glycogen Storage Disease and Type 1 Gaucher's Disease

Background: Liver transplantation for type IV glycogen storage disease (branching-enzyme deficiency) results in the resorption of extrahepatic deposits of amylopectin, but the mechanism of resorption is not known. Methods: We studied two patients with type IV glycogen storage disease 37 and 91 months after liver transplantation and a third patient with lysosomal glucocerebrosidase deficiency (type 1 Gaucher's disease), in whom tissue glucocerebroside deposition had decreased 26 months after liver replacement, to determine whether the migration of cells from the allograft (microchimerism) could explain the improved metabolism of enzyme-deficient tissues in the recipient. Samples of blood and biopsy specimens of the skin, lymph nodes, heart, bone marrow, or intestine were examined immunocytochemically with the use of donor-specific monoclonal anti-HLA antibodies and the polymerase chain reaction, with preliminary amplification specific to donor alleles of the gene for the beta chain of HLA-DR molecules, followed by hybridization with allele-specific oligonucleotide probes. Results: Histopathological examination revealed that the cardiac deposits of amylopectin in the patients with glycogen storage disease and the lymph-node deposits of glucocerebroside in the patient with Gaucher's disease were dramatically reduced after transplantation. Immunocytochemical analysis showed cells containing the HLA phenotypes of the donor in the heart and skin of the patients with glycogen storage disease and in the lymph nodes, but not the skin, of the patient with Gaucher's disease. Polymerase-chain-reaction analysis demonstrated donor HLA-DR DNA in the heart of both patients with glycogen storage disease, in the skin of one of them, and in the skin, intestine, blood, and bone marrow of the patient with Gaucher's disease. Conclusions: Systemic microchimerism occurs after liver allotransplantation and can ameliorate pancellular enzyme deficiencies., In patients with type IV glycogen storage disease, deficiency of the branching enzyme α-1,4-glucan:α-1,4-glucan 6-glucosyltransferase is responsible for the accumulation in the liver and elsewhere of an insoluble and irritating amylopectin-like polysaccharide1. We recently described the absorption of this amylopectin from the extrahepatic tissues after liver transplantation,2 leading Howell to predict that an explanation of the benefit would “clearly teach us a great deal about transplantation”3. That prediction has been shown to be accurate by our observation in this study that patients with type IV glycogen storage disease in whom liver transplantation was successful became chimeras: the cells… © 1993, Massachusetts Medical Society. All rights reserved

Production of Donor T Cells Is Critical for Induction of Donor-Specific Tolerance and Maintenance of Chimerism

Abstract Nonmyeloablative conditioning has significantly reduced the morbidity associated with bone marrow transplantation. The donor hemopoietic cell lineage(s) responsible for the induction and maintenance of tolerance in nonmyeloablatively conditioned recipients is not defined. In the present studies we evaluated which hemopoietic stem cell-derived components are critical to the induction of tolerance in a total body irradiation-based model. Recipient B10 mice were pretreated with mAbs and transplanted with allogeneic B10.BR bone marrow after conditioning with 100–300 cGy total body irradiation. The proportion of recipients engrafting increased in a dose-dependent fashion. All chimeric recipients exhibited multilineage donor cell production. However, induction of tolerance correlated strictly with early production of donor T cells. The chimeras without donor T cells rejected donor skin grafts and demonstrated strong antidonor reactivity in vitro, while possessing high levels of donor chimerism. These animals lost chimerism within 8 mo. Differentiation into T cells was aborted at a prethymic stage in recipients that did not produce donor T cells. Moreover, donor Ag-driven clonal deletion of recipient T cells occurred only in chimeras with donor T cells. These results demonstrate that donor T cell production is critical in the induction of transplantation tolerance and the maintenance of durable chimerism. In addition, donor T cell production directly correlates with the deletion of potentially alloreactive cells.</jats:p

The Need for Inducing Tolerance in Vascularized Composite Allotransplantation

Successful hand and face transplantation in the last decade has firmly established the field of vascularized composite allotransplantation (VCA). The experience in VCA has thus far been very similar to solid organ transplantation in terms of the morbidity associated with long-term immunosuppression. The unique immunological features of VCA such as split tolerance and resistance to chronic rejection are being investigated. Simultaneously there has been laboratory work studying tolerogenic protocols in animal VCA models. In order to optimize VCA outcomes, translational studies are needed to develop less toxic immunosuppression and possibly achieve donor-specific tolerance. This article reviews the immunology, animal models, mixed chimerism &amp; tolerance induction in VCA and the direction of future research to enable better understanding and wider application of VCA

Plasmacytoid precursor dendritic cells facilitate allogeneic hematopoietic stem cell engraftment

Bone marrow transplantation offers great promise for treating a number of disease states. However, the widespread application of this approach is dependent upon the development of less toxic methods to establish chimerism and avoid graft-versus-host disease (GVHD). CD8+/TCR− facilitating cells (FCs) have been shown to enhance engraftment of hematopoietic stem cells (HSCs) in allogeneic recipients without causing GVHD. In the present studies, we have identified the main subpopulation of FCs as plasmacytoid precursor dendritic cells (p-preDCs). FCs and p-preDCs share many phenotypic, morphological, and functional features: both produce IFN-α and TNF-α, both are activated by toll-like receptor (TLR)-9 ligand (CpG ODN) stimulation, and both expand and mature after Flt3 ligand (FL) treatment. FL-mobilized FCs, most of which express a preDC phenotype, significantly enhance engraftment of HSCs and induce donor-specific tolerance to skin allografts. However, p-preDCs alone or p-preDCs from the FC population facilitate HSC engraftment less efficiently than total FCs. Moreover, FCs depleted of preDCs completely fail to facilitate HSC engraftment. These results are the first to define a direct functional role for p-preDCs in HSC engraftment, and also suggest that p-preDCs need to be in a certain state of maturation/activation to be fully functional

HLA molecular mismatches and induced donor-specific tolerance in combined living donor kidney and hematopoietic stem cell transplantation

IntroductionWe investigated the potential role of HLA molecular mismatches (MM) in achieving stable chimerism, allowing for donor-specific tolerance in patients undergoing combined living donor kidney and hematopoietic stem cell transplantation (HSCT).MethodsAll patients with available DNA samples (N=32) who participated in a phase 2 clinical trial (NCT00498160) where they received an HLA mismatched co-transplantation of living donor kidney and facilitating cell-enriched HSCT were included in this study. High-resolution HLA genotyping data were used to calculate HLA amino acid mismatches (AAMM), Eplet MM, three-dimensional electrostatic mismatch scores (EMS-3D), PIRCHE scores, HLA-DPB1 T-cell epitope group MM, HLA-B leader sequence MM, and KIR ligands MM between the donor and recipient in both directions. HLA MM were analyzed to test for correlation with the development of chimerism, graft vs. host disease (GvHD), de novo DSA, and graft rejection.ResultsFollow-up time of this cohort was 6–13.5 years. Of the 32 patients, 26 developed high-level donor or mixed stable chimerism, followed by complete withdrawal of immunosuppression (IS) in 25 patients. The remaining six of the 32 patients had transient chimerism or no engraftment and were maintained on IS (On-IS). In host versus graft direction, a trend toward higher median number of HLA-DRB1 MM scores was seen in patients On-IS compared to patients with high-level donor/mixed chimerism, using any of the HLA MM modalities; however, initial statistical significance was observed only for the EMS-3D score (0.45 [IQR, 0.30–0.61] vs. 0.24 [IQR, 0.18–0.36], respectively; p=0.036), which was lost when applying the Bonferroni correction. No statistically significant differences between the two groups were observed for AAMM, EMS-3D, Eplet MM, and PIRCHE-II scores calculated in graft versus host direction. No associations were found between development of chimerism and GvHD and non-permissive HLA-DPB1 T-cell epitope group MM, HLA-B leader sequence, and KIR ligands MM.ConclusionOur results suggest an association between HLA-DRB1 molecular mismatches and achieving stable chimerism, particularly when electrostatic quality of the mismatch is considered. The non-permissive HLA-DPB1 T-cell epitope group, HLA-B leader sequence, and KIR ligands MM do not predict chimerism and GvHD in this combined kidney/HSCT transplant patient cohort. Further work is needed to validate our findings.Clinical trial registrationhttps://clinicaltrials.gov/study/NCT00498160, identifier NCT00498160

Novel regulatory therapies for prevention of Graft-versus-host disease

Graft-versus-host disease is one of the major transplant-related complications in allogeneic hematopoietic stem cell transplantation. Continued efforts have been made to prevent the occurrence of severe graft-versus-host disease by eliminating or suppressing donor-derived effector T cells. Conventional immunosuppression does not adequately prevent graft-versus-host disease, especially in mismatched transplants. Unfortunately, elimination of donor-derived T cells impairs stem cell engraftment, and delays immunologic reconstitution, rendering the recipient susceptible to post-transplant infections and disease relapse, with potentially lethal consequences. In this review, we discuss the role of dynamic immune regulation in controlling graft-versus-host disease, and how cell-based therapies are being developed using regulatory T cells and other tolerogenic cells for the prevention and treatment of graft-versus-host disease. In addition, advances in the design of cytoreductive conditioning regimens to selectively target graft-versus-host disease-inducing donor-derived T cells that have improved the safety of allogeneic stem cell transplantation are reviewed. Finally, we discuss advances in our understanding of the tolerogenic facilitating cell population, a phenotypically and functionally distinct population of bone marrow-derived cells which promote hematopoietic stem cell engraftment while reducing the risk of graft-versus-host disease

Hematopoietic Mononuclear Cell Transplant with Minimal Gvhd in up to Completely Mismatched Unrelated Recipients

37 patients have been transplanted in a phase 2 protocol to establish chimerism to induce tolerance in up to 0 of 6 matched related and unrelated recipients of living donor renal allografts (KTx). The protocol is based upon tolerogenic CD8+/TCR- facilitating cells (FC) and nonmyeloablative conditioning. Recipients were conditioned with fludarabine (30mg/m2 days -5,-4,-3), cyclophosphamide (50mg/kg day-3 and+3), 200 cGy TBI (day-1) followed by KTx (day0). G-CSF mobilized peripheral blood mononuclear cells were apheresed from the donor &gt;2 weeks before kidney transplantation, processed to remove graft-versus-host disease (GVHD)-producing cells yet retain CD34 +cells and FC, and cryopreserved until transplantation on day+1 after kidney transplantation. Immunosuppression consisted of mycophenolate mofetil and tacrolimus. 36 patients have reached at least 1 year of follow up (range 12-105 months) and are the focus of this analysis. Patients ranged in age from 18-65 yrs. Enrollment was agnostic to degree of HLA match; 2 were 6/6 and 3 5/6 matched related using high resolution allele level typing, with the remainder 4/6 to 0/6 matched related (n=15) or unrelated (n=16) Two of the recipients were renal re-transplants. Tacrolimus/MMF immunosuppression (IS) was weaned and discontinued at 1 year if chimerism (&gt;50% whole blood and T cell), normal renal function and normal kidney transplant biopsy were noted. 34 of 36 subjects exhibited peripheral blood donor chimerism at one month post KTx. Durable chimerism allowing for full IS withdrawal developed in 26 (time off IS from 1- 88 months); the majority (23/26) showed &gt;95% donor whole blood/T cell chimerism. Three have exhibited stable-mixed chimerism ranging between 40% - 60%. Three patients failed to develop chimerism. Transient chimerism occurred in 8 patients. Durably chimeric patients retained chimerism after removal of IS, remain rejection-free without donor-specific antibody (DSA) and show immunocompetence to vaccinations. None have had to resume immunosuppression. Transiently chimeric subjects resumed endogenous hematopoiesis and are maintained on low-dose IS with stable renal function. There have been two cases of GVHD: one grade 2 lower GI acute GVHD that developed during conversion from tacrolimus to sirolimus that responded to steroids; this patient has developed moderate chronic GVHD of the skin. He is off IS. The second presented late following development of severe gastrointestinal symptoms and manifested treatment-resistant lower GI GVHD with associated tissue-invasive CMV colitis that proved fatal at 11 months post-Tx. There have been two additional kidney graft losses, both related to early infections. A second subject death occurred in a heavy (&gt;100 pack yr) smoker who developed advanced stage lung cancer 4.5 years after Tx. A third subject developed pneumococcal sepsis &gt; 4 years after transplant. He had not undergone the recommended pneumococcal vaccination post HSCT. Overall patient survival is 91.8% and death censored graft survival 94.1%. These rates compare favorably to treatment-related mortality rates after standard of care renal transplant. In summary, high levels of durable chimerism and tolerance with a low (5.5%) incidence of GVHD has been achieved in up to 0 of 6 matched related and unrelated recipients of FCR001 + kidney transplant. Figure Disclosures Ildstad: Talaris Therapeutics Inc: Employment, Equity Ownership, Other: Founder and CSO. </jats:sec