Induction of donor-specific T cell anergy by portal venous injection of allogeneic cells

Oral tolerance: can we make it work?

Mucosal tolerance remains an attractive approach for the treatment of autoimmune and inflammatory diseases. The agents used in these treatments lack toxicity, can be easily administered, and enable the promotion of antigen-specific immune responses. The limited success of clinical trials over the past 2 decades has led to the fear that the beneficial effect observed in animal models cannot be repeated in humans. Successful application of mucosal tolerance for the treatment of human diseases will depend on strategies that target the correct cells in the gut-liver axis, improve antigen presentation, alter the administered dose and formulations, utilize potent mucosal adjuvants, develop immune biomarkers enabling follow-up of the effect, utilize combination therapies with other immune modulatory agents, and target the right patient populations. Here, we discuss 12 of the major questions related to oral tolerance and its clinical application to humans with immune-mediated disorders.

High-dose total body irradiation and bone marrow cells may improve efficiency of bone marrow transplantation therapy in treating type 1 diabetes

Bone marrow transplantation (BMT) has been used to treat autoimmune diseases for many years. Insulin-dependent diabetes mellitus (IDDM), also called type 1 diabetes mellitus (T1DM), is a T cell-mediated autoimmune disease resulting from a selective destruction of pancreatic islet beta cells. Recently, T1D has been a common significant cause of morbidity and mortality. However, whether BMT can be used to treat T1DM is still controversial. During BMT procedure, recipients underwent total body irradiation (TBI) and subsequent bone marrow cells (BMCs) infusion, in which TBI kills off the most T lymphocytes and BMCs stimulates hematopoiesis and immune reconstitution. We suggest that high-dose TBI and BMCs may improve efficiency of BMT therapy in T1DM treatment.

Generation of canine dendritic cells from peripheral blood monocytes without using purified cytokines

Dendritic cells (DCs), which differentiate in vitro from peripheral blood monocytes (PBMOs) or bone marrow precursors, are a promising candidate for immunotherapy against cancer. The dog, which suffers common types of cancers along with humans, make an ideal large animal model for cancer studies. Monocyte-derived DCs in the dog have not been well characterized, however, since the appropriate condition for in vitro differentiation has not been established. To tackle this problem, we have developed a conditioned media by culturing T cells with immobilized anti-canine CD3 antibody, and sought to induce differentiation of DCs from PBMOs. When purified CD14+ PBMOs were cultured in the presence of 25% T cell conditioned medium (TCCM), the PBMOs increased size and had extended dendritic processes by day 12 of the culture. The cultured PBMOs were found to increase the expression of MHC class II and CD1a molecules, and significantly increased stimulatory activity for allogeneic T cells in the mixed leukocyte reaction. Moreover, the cells significantly increased their expression of IL-18 and IFN-gamma when stimulated with polyinosinic-polycytidylic acid (Poly (I:C)). The cells have a reduced phagocytic activity, which is a common defect in mature DCs. It follows from these results that TCCM does induce the differentiation of DCs from PBMOs.

Synergistic effects of injection of bone marrow cells into both portal vein and bone marrow on tolerance induction in transplantation of allogeneic pancreatic islets

We have established a new method for allogeneic pancreatic islet (PI) transplantation: relatively low doses of irradiation followed by simultaneous transplantation of PIs and bone marrow cells (BMCs) via the portal vein (PV). In the present study, we have compared this method with intra-bone marrow (IBM)-bone marrow transplantation (BMT), and with a combination of both methods. Streptozotocin (STZ)-induced diabetic-recipient rats, Fischer 344 (F344, RT1A(l), RT1B(l)), were irradiated 1 day before transplantation. PIs of Brown Norway rats (BN, RT1A(n), RT1B(n)) were transplanted into the liver of the diabetic F344 rats via the PV. BMCs from BN rats were injected into the recipients' bone marrow (IBM), PV or intravenously (IV) or by a simultaneous combination of PV plus IBM (PV+IBM). We compared graft survival among the groups of '9 Gy+IBM'(10/10 accepted), '9 Gy+PV'(7/10 accepted), '9 Gy+IV'(0/7 accepted), '9 Gy+PV+IBM'(8/8 accepted), '8.5 Gy+IBM'(4/9 accepted), '8.5 Gy+PV'(0/7 accepted), '8.5 Gy+IV'(0/7 accepted), '8.5 Gy+PV+IBM'(9/12 accepted), '8 Gy+IBM'(2/10 accepted) and '8 Gy+PV+IBM'(2/8 accepted). As we reported previously, PV-BMT is more effective in inducing the acceptance of allogeneic PIs than IV-BMT. However, IBM-BMT requires less pretreatment than PV-BMT. (PV+IBM)-BMT was found to be the most effective in inducing the acceptance of allogeneic PIs. These results suggest that allogeneic PI-transplantation in conjunction with (PV+IBM)-BMT could become a viable strategy.

Treatment of streptozotocin-induced diabetes mellitus in rats by transplantation of islet cells from two major histocompatibility complex disparate rats in combination with intra bone marrow injection of allogeneic bone marrow cells

BACKGROUND

We have established a new method for the transplantation of allogeneic pancreatic islets obtained from two different rat strains in combination with a newly developed bone marrow transplantation (BMT) method in which bone marrow cells (BMCs) are directly injected into the bone marrow cavity (intra bone marrow BMT [IBM-BMT]).

METHODS

Streptozotocin-induced diabetic Brown Norway (BN: RT1A(n)) rats were injected with fludarabine, irradiated with 5.0 Gy x 2, and BMCs from two allogeneic rat strains, Fischer 344 (F344: RT1A(1)) and PVG (PVG: RT1A(c)), were then directly injected into the bone marrow cavity (IBM-BMT). Simultaneously, approximately 600 pancreatic islets (PIs) from F344 and PVG rats were mixed and transplanted into the liver by way of the portal vein.

RESULTS

All the recipients thus treated showed normoglycemia 30 days after the treatment. Hematolymphoid cells were completely reconstituted with the two donor-type cells, and immunologic tolerance to F344 and PVG major histocompatibility complex (MHC) determinants were induced.

CONCLUSIONS

The transplantation of PIs from two MHC-disparate donors was completely achieved in combination with IBM-BMT, resulting in the improvement of blood glucose levels and the amelioration of diabetes mellitus.

Liver sinusoidal endothelial cells are insufficient to activate T cells

Liver sinusoidal endothelial cells (LSEC) have been reported to express MHC class II, CD80, CD86, and CD11c and effectively stimulate naive T cells. Because dendritic cells (DC) are known to possess these characteristics, we sought to directly compare the phenotype and function of murine LSEC and DC. Nonparenchymal cells from C57BL/6 mice were obtained by collagenase digestion of the liver followed by density gradient centrifugation. From the enriched nonparenchymal cell fraction, LSEC (CD45(-)) were then isolated to 99% purity using immunomagnetic beads. Flow cytometric analysis of LSEC demonstrated high expression of CD31, von Willebrand factor, and FcgammaRs. However, unlike DC, LSEC had low or absent expression of MHC class II, CD86, and CD11c. LSEC demonstrated a high capacity for Ag uptake in vitro and in vivo. Although acetylated low-density lipoprotein uptake has been purported to be a specific function of LSEC, we found DC captured acetylated low-density lipoprotein to a similar extent in vivo. Consistent with their phenotype, LSEC were poor stimulators of allogeneic T cells. Furthermore, in the absence of exogenous costimulation, LSEC induced negligible proliferation of CD4(+) or CD8(+) TCR-transgenic T cells. Thus, contrary to previous reports, our data indicate that LSEC alone are insufficient to activate naive T cells.

Induction of antigen-specific CD4+ T-cell anergy and deletion by in vivo viral gene transfer

Immune responses to the therapeutic gene product are a potentially serious complication in treatment of genetic disease by gene therapy. Induction and maintenance of immunologic hypo-responsiveness to the therapeutic antigen is therefore critical to the success of gene-based treatment of inherited protein deficiency. Here, we demonstrate induction of antigen-specific CD4+ T-cell tolerance to a secreted transgene product (ovalbumin, ova) in ova-specific T-cell receptor (TCR) transgenic mice by hepatic adeno-associated virus (AAV)-mediated gene transfer. Transduced mice maintained stable circulating ova levels without evidence of an immune response. Lymph node cells and splenocytes were hypo-responsive to ova as early as day 10 after gene transfer. Numbers of TCR+CD4+ cells were reduced in secondary lymphoid organs and in the thymus by 1 to 2 months after vector administration. The remaining TCR+CD4+ cell population was anergic to ova antigen in vitro and enriched for CD25+ cells. These data provide direct evidence that transgene expression following in vivo viral gene transfer can induce CD4+ T-cell tolerance to the transgene product, involving anergy and deletion mechanisms.

Impact of portal venous pancreas graft drainage on kidney graft outcome in simultaneous pancreas-kidney recipients reported to UNOS

Clinical data on the potential immunologic impact of portal (PD) vs. systemic (SD) venous pancreas graft drainage on outcome remains controversial. We reviewed the UNOS database to study the effect of PD vs. SD on the incidence of kidney graft rejection and survival in first cadaveric simultaneous pancreas-kidney (SPK) recipients transplanted 1994-2001. We studied three groups: all SPK (n=6629, 13% PD) (group I), SPK on tacrolimus (n=3563, 17% PD) (group II), and SPK on tacrolimus performed at centers with significant PD experience (n=948, 46% PD) (group III). The cumulative kidney graft rejection incidence for PD vs. SD was only significantly different in group I (for PD vs. SD, respectively: at 6 months, 31% vs. 36% [p=0.015]; at 1 year, 37% vs. 43% [p=0.006]). Kidney graft survival was similar in all groups for PD vs. SD. Multivariate analysis of group III showed only transplantation during the earlier era (1994-96), but not SD, to be an independent risk factor for kidney graft rejection. Portal venous pancreas graft drainage does not affect kidney graft rejection and survival in SPK recipients on tacrolimus. Our data suggests that the efficacy of current immunosuppressive protocols and increasing center experience are clinically much more relevant than any potential immunologic advantage of portal venous drainage in SPK recipients.

Induction of oral tolerance and the effect of interleukin-4 on murine skin allograft rejection

We studied the effect of oral and portal vein administration of alloantigens on mouse skin allograft survival. Graft receptor BALB/c mice received spleen cells (30, 90, 150 or 375 x 10(6)) from donor C57BL/6 mice intragastrically on three successive days, starting seven days before the skin graft. Allograft survival was significantly increased with the feeding of 150 x 10(6) allogeneic spleen cells by one gavage (median survival of 12 vs 14 days, P< or =0.005) or when 300 x 10(6) cells were given in six gavage (12 vs 14 days, P<0.04). A similar effect was observed when 150 x 10(6) spleen cells were injected into the portal vein (12 vs 14 days, P< or =0.03). Furthermore, prolonged allograft survival was observed with subcutaneous (12 vs 16 days, P< or =0.002) or systemic (12 vs 15 days, P< or =0.016) application of murine interleukin-4 (IL-4), alone or in combination with spleen cell injection into the portal vein (12 vs 18 days, P< or =0.0018). Taken together, these results showed that tolerance induction with spleen cells expressing fully incompatible antigens by oral administration or intraportal injection partially down-modulates skin allograft rejection. Furthermore, these findings demonstrated for the first time the effect of subcutaneous or systemic IL-4 application on allograft skin survival suggesting its use as a beneficial support therapy in combination with a tolerance induction protocol.

Composite vascularized skin/bone graft model: A viable source for vascularized bone marrow transplantation

In this study, we introduce a new model for vascularized skin and bone marrow transplantation. Twenty-five Lewis (RT1(1)) rats were studied. Anatomic dissection studies were performed in 5 animals. In the experimental group, 10 isograft transplantations were performed between Lewis rats. Combined groin skin and femoral bone flaps were transplanted based on the femoral artery and vein. Transplants were evaluated on a daily basis. All flaps survived without problems over 100 days posttransplant. The skin component remained pink and pliable, and grew new hair. Histological examination of the femoral bone (except the femoral head) revealed active hematopoiesis with a viable compact and cancellous bone components on day 100 posttransplant. This model can be applied to tolerance induction studies across the major Histocompatibility (MHC) barrier, where bone will serve as donor of stem and progenitor cells, and the skin flap will serve as a monitor of graft rejection.

Donor-specific tolerance induced by simultaneous allogeneic islet transplantation with CD4+CD25+T-cells into hepatic parenchyma in mice

BACKGROUND

The allogeneic islets transplantation is an ideal therapeutic strategy for patients with diabetes mellitus. However, it has been difficult to induce immunological tolerance against islets grafts. The CD4+CD25+ regulatory T-cells (Treg) play a role in suppressing T-cell activation. Thus, we evaluated whether Treg can regulate donor-specific T-cell tolerance that received allogeneic islets into the hepatic parenchyma (ITxHP) along with Treg.

METHODS

C3H/He mice were used as donors; and streptozotocin-induced diabetic BALB/c mice were recipients. The protocol included three groups: Group A recipients received only 300 IE islets; Group B was given 300 IE islets and whole splenocytes; Group C was given 300 IE islets and Treg purified from peripheral lymph nodes.

RESULTS

For all mice in Groups A and B, the fasting blood sugar exceeded 250mg/dl and graft rejection was observed. GVHD was observed earlier in Group B than in Group A. In contrast graft survival exceeded 30 days for two mice in Group C (50%, mean POD 28.5 +/- 24.0, P<0.05). Mixed lymphocyte reaction showed that T-cells from tolerant mice had very weak responses against spleen cells from C3H mice.

CONCLUSIONS

The simultaneous ITxHP with CD4+CD25+ T-cells administration prolonged islet graft survivals and induced donor-specific hyporesponsiveness.

Simultaneous administration of a low-dose mixture of donor bone marrow cells and splenocytes plus adenovirus containing the CTLA4Ig gene result in stable mixed chimerism and long-term survival of cardiac allograft in rats

T-cell costimulatory blockade combined with donor bone marrow transfusion may induce mixed chimerism, rendering robust tolerance in transplanted organs and cells. However, most protocols entail high doses of donor bone marrow cells (BMCs) or repeated administration of costly agents that block costimulatory pathways, thus delaying clinical development. To circumvent these shortcomings, we developed a strategy in which the dosage of donor BMCs was reduced but compensated by donor splenocytes (SPLCs). Furthermore, repeated administration of costly agents was replaced with a single injection of adenovirus expressing a gene of interest. In rat cardiac transplantation models, cardiac allografts from DA (RT-1a) rats were transplanted heterotopically into the abdomen of LEW (RT-11) recipient rats. Immediately after cardiac transplantation, an adenovirus vector (AdCTLA4Ig; 5 x 10(9) plaque-forming units) containing the gene for CTLA4Ig was administered to recipients (n = 6) simultaneously with a low dose of donor BMCs (1 x 10(8)/rat) and SPLCs (5 x 10(7)/rat) via the portal vein. The treated LEW recipient rats developed long-lasting mixed chimerism (>10% at >100 days) and exhibited long-term cardiac allografts (mean survival time of > 200 days) compared with control recipients. Moreover, recipients displaying long-lasting mixed chimerism accepted subsequent donor skin allografts while promptly rejecting third-party skin allografts. These results suggest that blockade of the CD28-B7 pathway, using adenovirus-mediated CTLA4Ig gene transfer, in concert with a low dosage of donor BMCs and SPLCs, may represent a feasible strategy to induce stable mixed chimerism and permit long-term survival of cardiac allografts.

Intraportal donor bone marrow transplantation improves intestinal allograft survival in rats under FK506-based immunosuppression

Donor-specific immunosuppression is important in transplant surgery. We examined the effect of intraportal donor-specific bone marrow transplantation on heterotopic small bowel transplantation in the high responder rat combination, ACI to Lewis. The study comprised five treatment groups: untreated controls (group 1); FK506 alone (group 2); low-dose predonine + FK506 (group 3); high-dose predonine + FK506 (group 4); and intraportal donor-specific bone marrow transplantation + FK506 (group 5). Intraportal transplantation was performed pre-operatively and FK506 and predonine given post-operatively. Intestinal allograft survival and changes of intragraft cytokine expression were analysed using the reverse transcription polymerase chain reaction. Allograft survival (mean +/- SD) was lowest in group 1 and greatest in group 5. The group 5 treatment regimen also down-regulated interferon-gamma and interleukin-2 transcription in the transplanted intestine. Intraportal donor bone marrow transplant combined with FK506 immunosuppression was found therefore to be the most beneficial treatment regimen.

Treatment of autoimmune diseases in mice by a new method for allogeneic bone marrow transplantation

Remarkable advances have been made in bone marrow transplantation (BMT), which has become a powerful strategy for the treatment of leukemia, aplastic anemia, congenital immunodeficiency, and also autoimmune disease. Using various animal models, allogeneic (allo) BMT has been found to be useful in the treatment of various autoimmune diseases. In MRL/lpr mice, which are radiosensitive (<8.5 Gy) and are an animal model for autoimmune diseases, conventional BMT resulted in only transient effects; the manifestations of the autoimmune diseases recurred 3 months after BMT. Using MRL/lpr mice, we have very recently established a new strategy for allo BMT. We injected bone marrow cells (BMC) directly into the bone marrow cavity (intrabone marrow [IBM] injection) of recipients that had received fractionated irradiation. This 'IBM-BMT' was found to be effective in treating autoimmune diseases in radiation-sensitive and chimeric-resistant MRL/lpr mice. In addition, this strategy was found to be applicable for the transplantation of organs. We believe that these strategies for BMT and organ transplantation herald a new era in transplantation.

Mixed peripheral blood stem cell transplantation for autoimmune disease in BXSB/MpJ mice

We examined whether mixed allogeneic transplantation with syngeneic plus allogeneic peripheral blood stem cells (PBSCs) is sufficient to interrupt autoimmune processes in BXSB mice and confer a potential therapeutic option for the treatment of patients with autoimmune diseases. Eight-week-old BXSB mice were lethally irradiated and reconstituted with BALB/c (H-2d)+BXSB (H-2b) PBSCs, in which the number of injected allogeneic progenitor cells was 5 times that of syngeneic progenitor cells. The survival of mixed PBSC chimeras (BALB/c+BXSB→BXSB) was 80% at the age of 48 weeks, whereas that of full chimeras (BALB/c→BXSB) was 90%. Mixed PBSC transplantation (PBSCT) prevented the production of anti-DNA antibodies and the development of lupus nephritis in BXSB recipients and induced tolerance to both allogeneic and syngeneic antigens. Moreover, mixed chimeras exhibited immunological functions superior to fully allogeneic chimeras. On the other hand, increases in the number of BXSB PBSCs resulted in the transfer of lupus nephritis in BXSB+BALB/c→BALB/c mice. Thus, the number of hematopoietic progenitor cells from normal mice proved critical to the prevention of autoimmune diseases. We propose that mixed allogeneic PBSCT for the interruption of the autoimmune process can be carried out by injecting increased numbers of allogeneic normal hematopoietic progenitor cells to prevent the relapse of autoimmune diseases, although it is necessary to decide upon a minimum dose of syngeneic PBSCs to achieve the desired beneficial effects on autoimmunity.

Allogeneic chimerism established with a mixture of low dose bone marrow cells and splenocytes in sublethally irradiated mice

BACKGROUND

Allogeneic chimerism has been established in graft-accepting recipients and the donor cells in the host may act in a major way to facilitate the induction of tolerance. In this study, we examined the effects of allogeneic chimerism after injecting donor bone marrow cells (BMCs) mixed with splenocytes (SPLCs) to the sublethally conditioned recipients.

METHODS

In BALB/c(H-2(d)) to B6(H-2(b)) combination, B6 recipients were irradiated at 7.5 Gy and were injected a mixture of donor BMCs and SPLCs intravenously. On day 90 after injection, the degree of chimerism in peripheral blood lymphocytes (PBL) and in the splenocytes was checked by flow cytometry.

RESULTS

In groups which were injected varying BMCs, when > 45 x 10(6) BMCs were injected into B6, a large percentage of donor cells were detected in PBL and in the spleen. In contrast, when < 30 x 10(6) BMCs were injected into B6, only a small percentage of donor cells were detected. In the groups which were injected 3 x 10(6) BMCs with varying SPLCs, when > 10 x 10(6) SPLCs were added, a large percentage of donor cells were detected in PBL and SPLCs, but a small percentage of donor cells were detected with the addition of < 3 x 10(6) SPLCs. A high percentage of chimeric mice showed donor specific tolerance in vitro, mixed lymphocyte responses, and in vivo, skin grafting. In contrast, only a small percentage of chimeric mice showed no donor specific tolerance by skin grafting.

CONCLUSION

These findings suggested that even a low dose of BMCs can establish a state of allogeneic chimerism and donor specific tolerance if combined with SPLCs.

Differentiation-dependent and subset-specific recruitment of T-helper cells into murine liver

It has been suggested that the liver traps and deletes activated and potentially harmful T cells, especially of the CD8(+) subset, providing mechanisms to limit systemic immune responses. It is unknown whether this also applies to CD4(+) T cells. In this study, we show that activated stages of CD4(+) T cells were trapped in the liver on intraportal injection. Intravital microscopy showed an immediate adhesion of activated CD4(+) T cells within periportal sinusoids after intraportal injection. Furthermore, we detected high frequencies of interferon gamma (IFN-gamma)-- (Th1) and interleukin 4 (IL-4)-- (Th2) synthesizing effector cells in the liver. Transfer experiments were performed to identify those phenotypes showing specific retention in the liver. Our data show that effector stages and activated cells in general are more efficiently recruited into the liver than resting CD4(+) T cells, similar to what has previously been shown for CD45RB(low) memory cells. In addition, we observed a certain preference for Th1-polarized cells to be trapped by the liver. However, the actual cytokine-producing cells did not specifically enrich among the total population. In conclusion, these data indicate that the liver acts as a filter for activated and memory/effector cells. Cells trapped in the liver might subsequently undergo modulatory influences exerted by the postulated specific microenvironment of the liver.

Treatment of streptozotocin-induced diabetes mellitus by transplantation of islet cells plus bone marrow cells via portal vein in rats

BACKGROUND

We have established a new method for the transplantation of allogeneic pancreatic islets (PIs) using sublethal irradiation (9 Gy) plus simultaneous transplantation of PIs and bone marrow cells (BMCs) via the portal vein (PV) followed by intravenous (i.v.) injection of donor BMCs (9 Gy + PV + i.v.).

METHODS

Approximately 600 PIs of Brown Norway (BN: RT1An, RT1Bn) rats were transplanted into the liver of streptozotocin-induced diabetic Fischer 344 (F344: RT1Al, RT1Bl) rats via the PV. BMCs (3x108) of BN rats were injected via the PV or i.v. into the recipients simultaneously. In some groups, additional i.v. injections of BMCs from BN rats were given 5 days after the PI transplantation.

RESULTS

All the recipients (10 of 10) in the 9 Gy + PV + i.v. group showed normoglycemia for more than 1 year, whereas PIs were rejected within 30 days after transplantation in the group of 9 Gy + i.v. + i.v.

CONCLUSIONS

These results suggest that simultaneous transplantation of PIs and BMCs via the PV is effective in inducing persistent tolerance.

High-dose peripheral blood stem cell infusion: a strategy to induce donor-specific hyporesponsiveness to allografts in pediatric renal transplant recipients

We designed and implemented a clinical trial to achieve zero-rejection status in pediatric renal allograft recipients, using granulocyte-macrophage colony-stimulating factor (GM-CSF)-stimulated peripheral blood stem cell (PBSC) infusion. We studied 44 consecutive patients: 24 volunteers in a treated group (Tn) and 20 in a control group (Cn). Both groups were comparable with respect to clinical and laboratory parameters. The Tn group had 70.8% one haplo-match donors and the Cn group had 80% one haplo-match donors. Patients in the Tn group received cyclosporin A (CsA) and 0.4 mg/kg body weight prednisolone as immunosuppressants; azathioprine was added for patients of the Cn group, who received 1 mg/kg body weight prednisolone together with CsA. Living-related donors (LRD) of patients in the Tn group received GM-CSF 450 microg on four consecutive days followed by leucopheresis and immediate transfusion of unmodified PBSC into the recipient. This procedure was repeated once/twice, with one portal and one/two systemic infusions. Our aim was to maximize the dose of PBSC. The total average dose was 22 x 10(8) cells/kg body weight. Lymphocyte cross-match (LCM) was performed before GM-CSF injection and after the last PBSC infusion. Follow-up over an 18-month period revealed 100% graft survival with sustained low serum creatinine (SCr) values in patients of the Tn group as compared with 80% graft survival in patients of the control group who had marginally higher SCr levels. Absence of graft vs. host disease (GvHD), acute rejection episodes, and low incidence of cytomegalovirus (CMV) disease were the principal benefits of this protocol.

A new method for tolerance induction: busulfan administration followed by intravenous injection of neuraminidase-treated donor bone marrow

The portal venous (p.v.) administration of foreign cells induces donor-specific tolerance. Recently, we have demonstrated that the p.v. administration of donor cells elicits donor-specific tolerance across major histocompatibility complex barriers. In the present study, utilizing the intrahepatic tolerance-inducing system, we have established a new method for organ transplantation using both busulfan ([Bu] to provide a sufficient "space" for the donor hematopoietic cells to expand in the recipient) and neuraminidase ([Neu] to enhance the trapping of i.v.-injected cells in the liver). Radiolabeled bone marrow cells (BMCs) were found to exclusively accumulate in the livers of the recipients as a result of the Neu treatment. Furthermore, hematopoietic progenitors (forming hematopoietic foci) in the accumulated BMCs were retained in the recipient livers for at least 18 days. C57BL/6 (B6) mice that had been transplanted with skins of BALB/c mice immediately after the injection of BALB/c BMCs showed a 90% skin graft survival rate over 400 days as a result of using the combination of injecting 50 mg/kg Bu into the B6 mice and treatment of the BALB/c BMCs with 0.25 U/ml Neu (50 Bu + 0.25 Neu). However, the survival rate significantly decreased when either the Bu or Neu treatment was omitted. In tolerant recipients, microchimerism was observed in the various hematolymphoid organs. T cells collected from the tolerant recipients suppressed proliferative responses to the donor-alloantigens but enhanced the production of Th2 and Th3 cytokines. These findings suggest that the enhanced retention of donor BMCs in the recipient livers as a result of the Bu and Neu treatments efficiently induces tolerance induction. Therefore, this "single-day protocol" would be of great advantage for human organ transplantation.

Donor-derived soluble MHC antigens plus low-dose cyclosporine induce transplantation unresponsiveness independent of the thymus by down-regulating T cell-mediated alloresponses in a rat transplantation model

BACKGROUND

In vitro, soluble MHC (sMHC) antigens modulate and induce apoptosis in alloreactive and antigen-specific T cells, demonstrating their potency to regulate T cell-mediated immune responses. However, their efficacy to regulate immunological responses in vivo remains unclear. Here, we report that repetitive intraperitoneal injection of recombinant Lewis rat-derived MHC class I antigens in Dark Agouti (DA) rats modulates alloreactivity.

METHODS

RT1.A1 (Lewis derived) genes were cloned into mammalian expression vectors, and RT1.Aa (DA derived) genes were used to transfect a rat myeloma cell line. RT1.A1 molecules were injected intraperitoneally in DA recipients that subsequently underwent transplantation with Lewis-derived cardiac allografts.

RESULTS

Soluble class I antigens were secreted by the transfected cells and were shown to be heterodimeric, peptide-loaded, and conformationally folded. Injection of donor-derived soluble MHC significantly reduced the ability of recipient animals to mount a cytotoxic T-cell response to donor-derived tissue. More interestingly, this treatment significantly prolonged donor-graft survival and allowed 60% of treated animals to develop graft tolerance (>120 days), when donor sMHC were combined with a single subtherapeutic dosage of cyclosporine. Thymectomy of recipient animals before transplantation did not interfere with induction of peripheral tolerance.

CONCLUSIONS

Donor-derived sMHC are potential tolerogens for down-regulating the cytotoxic T-cell response of animals that undergo transplantation. Thus, these data provide for the first time a rationale for the application of directly injected sMHC in vivo to down-regulate immunological responses and aid the induction of graft tolerance.

New method for thyroid transplantation across major histocompatibility complex barriers using allogeneic bone marrow transplantation

BACKGROUND

It has been shown that allogeneic bone marrow transplantation (BMT) after lethal irradiation elicits donor-specific tolerance for organ or tissue transplantation across major histocompatibility complex (MHC) barriers. Recently, we have demonstrated that the portal venous (p.v.) administration of donor bone marrow cells (BMCs) elicits donor-specific tolerance across MHC barriers by only two administrations of an immunosuppressant (CsA or FK-506). In our study, using the central and intrahepatic tolerance-inducing system, we have established a new method for thyroid transplantation with BMT that would be more applicable to humans.

METHODS

In addition to sublethal (6-5 Gy) irradiation, recipient B6 (H-2b) mice received injections i.p. with the myeloablative drug busulfan (BU) on day -2 to provide a sufficient "space" for the donor hematopoietic cells to expand in the recipients. To induce the intrahepatic tolerance, donor BALB/c (H-2d) BMCs were treated with neuraminidase (Neu), which enhances the trapping of i.v. injected BMCs in the liver. After the injection of Neu-treated BMCs, the thyroid organs from the BALB/c mice were engrafted under the renal capsules.

RESULTS

A 90% graft survival rate was obtained over 100 days by a combination of BU administration, 6 Gy irradiation, and i.v. injection of Neu-treated BMCs [BU+6 Gy+(Neu) i.v.], and a 70% graft survival rate was obtained by [BU+5 Gy+(Neu) i.v.]. However, the graft survival rate significantly decreased when either the BU or Neu treatment was omitted. T cells collected from the tolerant recipients suppressed the proliferative responses to donor alloantigens.

CONCLUSIONS

Using both BU and Neu treatments, we have succeeded in inducing long-term tolerance and preventing the rejection of thyroid allografts by the single-day protocol.

Tolerance induction across Mls and minor histocompatibility complex by inhibiting activation of T helper type 1 in early period

We have previously succeeded in inducing persistent donor-specific tolerance across Mls plus multiple minor histocompatibility barriers by portal venous (p.v.) injection of donor spleen or bone marrow cells plus cyclophosphamide (CY) treatment. Microchimerism was established in the lymph-hemopoietic organs of the tolerant recipients. However, the mechanisms, particularly the roles of CY in the tolerance induction, have not been clarified. We examined the tolerance induction using other anti-mitotic agents and evaluated the in vitro proliferative responses and cytokine expression of T cells from the recipients after stimulation with donor alloantigens. The administration of not only CY but also mitomycin C (MMC) and cytosin arabinoside (Ara C) elicited a prolongation of skin graft survival. CY induced tolerance when it was administered 2 days after the p.v. injection, but not immediately or 4 days after the p.v. injection. T cells collected from the tolerant recipients showed no proliferative responses as a result of stimulation with donor alloantigens whereas the responses of T cells from non-tolerant recipients were significantly enhanced. Interferon-gamma (IFNgamma) was extensively expressed in the non-tolerant T cells from 24 to 48 h after the stimulation with donor alloantigens. In contrast, the expression of IFNgamma was observed in the tolerant T cells from 72 h after the stimulation. Also, the tolerant T cells showed the expression of interleukin-10 (IL-10) and transforming growth factor-beta 1 (TGF-beta1) from 72 h after the stimulation whereas the non-tolerant T cells did not. These data suggest that CY, when administered 2 days after the p.v. injection, induces persistent tolerance by inhibiting T helper type 1 (Th1) activity in the early period but not the Th1 activity in the later periods.

Crucial role of donor-derived stromal cells in successful treatment for intractable autoimmune diseases in mrl/lpr mice by bmt via portal vein

We have recently established a new bone marrow transplantation (BMT) method for the treatment of intractable autoimmune diseases in MRL/lpr mice; the method consists of fractionated irradiation (5.5 Gy x 2), followed by BMT of whole bone marrow cells (BMCs) from allogeneic C57BL/6 mice via the portal vein (abbreviated as 5.5 Gy x 2 + PV). In the present study, we investigate the mechanisms underlying the early engraftment of donor-derived cells in MRL/lpr mice by this method. In the mice treated with this method, the number of donor-derived cells possessing the mature lineage (Lin) markers rapidly increased in the BM, spleen, and liver; almost 100% were donor-derived cells by 14 days after the treatment. The number of donor-derived hemopoietic progenitor cells (defined as c-kit(+)/Lin(-) cells) increased in the BMCs, hepatic mononuclear cells, and especially spleen cells by 14 days after the treatment. Simultaneously, hemopoietic foci adjoining donor-derived stromal cells were observed in the liver when injected via the PV, but not via the peripheral vein (i.v.). When adherent cell-depleted BMCs were injected via the PV, recipients showed a marked reduction in the survival rate. However, when mice were transplanted with adherent cell-depleted BMCs with cultured stromal cells, all the recipients survived. These findings suggest that not only donor hematopoietic stem cells (HSCs) but also donor stromal cells administered via the PV were trapped in the liver, resulting in the early engraftment of donor HSCs in cooperation with donor-derived stromal cells. This new strategy to facilitate the early recovery of hemopoiesis would therefore be of great advantage in human application.

Successful allogeneic bone marrow transplantation (BMT) by injection of bone marrow cells via portal vein: stromal cells as BMT-facilitating cells

We examined the importance of the coadministration of bone marrow (BM) stromal cells with BM cells via the portal vein. A significant increase in the number of day-14 colony-forming unit-spleen (CFU-S) was observed in the recipient mice injected with hemopoietic stem cells (HSCs) along with donor BM stromal cells obtained after three to four weeks of culture. Histological examination revealed that hematopoietic colonies composed of both donor hemopoietic cells and stromal cells coexist in the liver of these mice. However, when donor HSCs plus BM stromal cells were administered i.v., neither the stimulatory effects on CFU-S formation nor the hemopoietic colonies in the recipient liver were observed. These findings suggest that the interaction of HSCs with stromal cells in the liver is the first crucial step for successful engraftment of allogeneic HSCs. It is likely that donor stromal cells and HSCs trapped in the liver migrate into the recipient BM and spleen, where they form CFU-BM and CFU-S, respectively.

A novel strategy for organ allografts using sublethal (7 Gy) irradiation followed by injection of donor bone marrow cells via portal vein

A new strategy for organ allografts that does not require recourse to immunosuppressants is established in mice. The strategy includes sublethal (7 Gy) irradiation followed by the injection of donor bone marrow cells (BMCs) via the portal vein (P.V.) and organ allografts 1 day after irradiation. Irradiation doses (< or =7 Gy) are found to allow the recipients to survive without the need to reconstitute the BMCs, as the recipient hematolymphoid cells can gradually recover. One hundred percent of recipients irradiated with 7 Gy followed by either P.V. or i.v. injection of donor BMCs accept organ allografts (the skin, pancreas, and adrenal glands) for more than 1 year. However, organ allograft survival rates decrease when irradiation doses are reduced; the skin graft survival rate of mice treated with 6.5 Gy and P.V. injection of BMCs is 79%, whereas that of mice treated with 6.5 Gy and i.v. injection is 50%, indicating that the P.V. injection of BMCs induces persistent tolerance more effectively than the i.v. injection. H-2 typing reveals that almost all the hematolymphoid cells (>98%) in the peripheral blood and hematolymphoid organs are donor-derived even 1 year after the treatment (7 Gy and P.V.). The T cells are tolerant to both donor-type and host-type MHC determinants. The major mechanism underlying the persistent tolerance induced by this strategy seems to be because of clonal deletion. This simple and safe strategy would be of great advantage for human organ transplantation.

Treatment of autoimmune diseases by hematopoietic stem cell transplantation

Remarkable advances have been made in bone marrow transplantation (BMT), which now has become a powerful strategy for the treatment of leukemia, aplastic anemia, congenital immunodeficiency disorders, and autoimmune diseases. Using various animal models, allogeneic BMT has been found to be useful in the treatment of autoimmune diseases. In MRL/lpr mice, which are radiosensitive (<8.5 Gy) and are an animal model for autoimmune disorders, conventional BMT resulted in only transient effects; the manifestations of the autoimmune diseases recurred 3 months after BMT. However, the combination of BMT plus bone grafts (to recruit donor stromal cells) was capable of preventing the recurrence of autoimmune diseases in MRL/lpr mice. This strategy was found to be ineffective in the treatment of MRL/lpr mice that had developed autoimmune diseases, because these mice were more sensitive to the effects of radiation after the onset of lupus nephritis due to uremic enterocolitis. We have recently discovered a safer strategy for treatment of autoimmune diseases, which includes fractionated irradiation (5.5 Gy x 2) (day -1) followed by portal venous injection (day 0) plus intravenous injection (day 5) of donor unfractionated bone marrow cells. We successfully treated autoimmune diseases in MRL/lpr mice using this strategy; 100% of MRL/lpr mice treated in this fashion survive >1 year after treatment. We identified the mechanisms underlying the components of this approach and have found that stromal cells play a crucial role in successful BMT. In this review, the conditions essential for successful allogeneic BMT are discussed.

Intra-bone marrow injection of allogeneic bone marrow cells: a powerful new strategy for treatment of intractable autoimmune diseases in MRL/lpr mice

Intractable autoimmune diseases in chimeric resistant MRL/lpr mice were treated by a new bone marrow transplantation (BMT) method consisting of fractionated irradiation, 5.5 Gy x 2, followed by intra-bone marrow (IBM) injection of whole bone marrow cells (BMCs) from allogeneic normal C57BL/6 (B6) mice (5.5 Gy x 2 + IBM). In MRL/lpr mice treated with this method, the number of donor-derived cells in the bone marrow, spleen, and liver rapidly increased (almost 100% donor-derived cells by 14 days after the treatment), and the number of donor-derived hemopoietic progenitor cells concomitantly increased. Furthermore, donor-derived stromal cells were clearly detected in the cultured bone pieces from MRL/lpr mice treated with 5.5 Gy x 2 + IBM. All the recipients thus treated survived more than 1 year (> 60 weeks after birth) and remained free from autoimmune diseases. Autoantibodies decreased to almost normal levels, and abnormal T cells (Thy1.2(+)/B220(+)/CD4(-)/CD8(-)) disappeared. Hematolymphoid cells were reconstituted with donor-derived cells, and newly developed T cells were tolerant to both donor (B6)-type and host (MRL/lpr)-type major histocompatibility complex determinants. Successful cooperation was achieved among T cells, B cells, and antigen-presenting cells when evaluated by in vitro antisheep red blood cell responses. These findings clearly indicate that this new strategy (IBM-BMT) creates the appropriate hemopoietic environment for the early recovery of hemopoiesis and donor cell engraftment, resulting in the complete amelioration of intractable autoimmune diseases in chimeric resistant MRL/lpr mice without recourse to immunosuppressants. This strategy would therefore be suitable for human therapy.

Implantation of xenografts into parkinsonian rat brain after portal venous administration of xenogeneic donor spleen cells

Object. The purpose of the present study was to examine the effect of pretransplantation portal venous immunization with ultraviolet B (UVB)—treated donor spleen cells on neural xenograft transplantation.

Methods. Cells from a murine catecholaminergic cell line derived from the B6/D2 F1 mouse, CATH.a, were used as a xenograft. Thirty hemiparkinsonian rats were divided into three different treatment groups. Group 1 received saline in the dopamine-denervated striatum; Group 2 received xenograft cells; and Group 3 received portal venous administration of UVB-irradiated B6/D2 F1 splenocytes 7 days before receiving xenograft cells. Xenograft function was determined by reviewing apomorphine-induced rotation at 2-week intervals, and xenograft survival was examined at 4 and 12 weeks after transplantation by immunohistochemical staining for murine tyrosine hydroxylase (THase). Rotational behavior was improved in both xenograft-transplanted groups (Groups 2 and 3); however, the animals in Group 3 displayed a significantly reduced rotational behavior compared with Group 2. In Group 2, many inflammatory cells and a few THase-positive cells were found at the graft sites 4 weeks after transplantation. In Group 3, however, a large number of THase-positive cells were found with few inflammatory cells. The THase-positive cells disappeared in the Group 2 rats at 12 weeks, but remained in Group 3 animals. In Group 3 rats proliferation of spleen cells in a mixed lymphocyte reaction was suppressed in a donor-specific fashion.

Conclusions. This work demonstrates improved neural xenograft survival and function by pretransplantation portal venous immunization with UVB-irradiated xenogeneic donor splenocytes. On the basis of these findings, the authors suggest the possibility of creating donor-specific immunological tolerance in the brain by administration of xenogeneic donor lymphocytes via the portal vein.

Long-term (>1 year) analyses of chimerism and tolerance in mixed allogeneic chimeric mice using normal mouse combinations

We examined the induction of tolerance using pancreas allografts over the long term (>1 year) in mice for the human application of mixed allogeneic bone marrow transplantation (BMT). T cell-depleted BM cells (BMCs) of C57BL/6 (B6) and C3H/He (C3H) mice were transplanted at various ratios into lethally irradiated B6 mice. The percentages of C3H cells in the chimeric mice gradually decreased, finally declining to only a small percentage, except when the ratio of donor to recipient BMCs was 100:1. However, despite the marked decreases in C3H-type cells, all the pancreas allografts of C3H mice were accepted when more than 1% C3H cells were detected in the peripheral blood. To examine the relationships between percentages of transplanted donor cells and acceptance of pancreas allografts, various percentages of donor and recipient BMCs (5% to 30%) were transplanted. It was found that more than 10% donor cells were necessary for the pancreas allografts to be accepted. In vitro assays for mixed lymphocyte reaction and generation of cytotoxic T-lymphocytes revealed that spleen cells in chimeric mice accepting pancreas allografts are tolerant to both host-type and donor-type major histocompatibility complex (MHC) determinants, but show a vigorous responsiveness to third-party MHC determinants. Since donor-type hemopoietic stem cells (HSCs) were detected in the BM and the liver of the chimeric mice, donor-derived HSCs and donor-derived hematolymphoid cells are responsible for the induction of tolerance. It should be noted that the percentage of donor-type HSCs is higher in the liver (6.2%) than in the BM (0.9%).

Treatment of intractable autoimmune diseases in MRL/lpr mice using a new strategy for allogeneic bone marrow transplantation

A new bone marrow transplantation (BMT) method for treating severe autoimmune diseases in chimeric resistant MRL/lpr mice is presented. The method consists of fractionated irradiation (5.5 Gy × 2), followed by portal venous (PV) injection of whole bone marrow cells (BMCs) from allogeneic normal C57BL/6 (B6) mice and intravenous (IV) injection of whole B6 BMCs 5 days after the PV injection (abbreviated as 5.5 Gy × 2 + PV + IV). All recipients survived more than 1 year after this treatment (more than 64 weeks after birth). Abnormal T cells (Thy1.2+/B220+/CD3+/CD4−/CD8−) present in MRL/lpr mice before the treatment disappear, and hematolymphoid cells are reconstituted with donor-derived cells. The treated mice are free from autoimmune diseases. Levels of autoantibodies (IgG/IgM anti-ssDNA antibodies and IgG/IgM rheumatoid factors) decrease to normal levels. Successful cooperation is achieved among T cells, B cells, and antigen-presenting cells (APCs) of the treated MRL/lpr mice when evaluated by in vitro anti-SRBC responses. Newly developed T cells are tolerant to both donor (B6)-type and host (MRL/lpr)-type major histocompatibility complex (MHC) determinants. These findings clearly indicate that severe autoimmune diseases in MRL/lpr mice are completely ameliorated by the treatment without recourse to immunosuppressants, and that the treated MRL/lpr mice show normal immune functions, strongly suggesting that this strategy would be applicable to humans.

Acceptance of skin allografts in pigs by portal venous injection of donor bone marrow cells

OBJECTIVE

To confirm in pigs whether a new method for organ allografts, originally established in mice by the authors, might be applicable to humans.

SUMMARY BACKGROUND DATA

The authors recently established a new method for organ allografts in mice that includes the injection of donor bone marrow cells (BMCs) using the portal vein (PV), followed by the administration of cyclosporin A (CsA) on days 2 and 5, and the intravenous injection of BMCs on day 5. In the present study, they modify this method (a single-day protocol) and apply it to pigs.

METHODS

Allogeneic BMCs of donor pigs were injected using the PV (a superior mesenteric vein). The skin grafting was carried out on the day of the PV injection. The recipient pigs received donor grafts, autologous grafts, and third-party grafts at the same time. In addition, an open wound was made as the epithelized control. Full-thickness skin grafts were harvested from the dorsal wall of the donors. CsA (10 mg/kg) was injected intramuscularly into recipient pigs on days 2 and 5 after the PV injection.

RESULTS

One hundred percent of skin grafts survived for >300 days when donor BMCs were injected using the PV (n = 6). However, the skin grafts of the three pigs that had received BMCs using the intravenous route were rejected within 3 to 4 weeks after transplantation. The third-party skin grafts showed necrotic changes on day 21 after transplantation.

CONCLUSIONS

One hundred percent of skin allografts can be obtained, even in pigs, by injecting donor BMCs using the PV, carrying out skin allografts, and administering CsA on days 2 and 5. This single-day protocol would be of great advantage for human organ transplantation.

A strategy for organ allografts without using immunosuppressants or irradiation

A strategy to achieve regular and long lasting organ and tissue allografts without using immunosuppressants and/or irradiation has been established for mice. One hundred percent of skin allografts can be induced to survive >350 days after transplantation if spleen cells from the same donors are first injected into the portal vein of the recipients. The mechanisms underlying this long-term tolerance induction can be described as follows: (i) donor T cells from the spleen of the donor facilitate the acceptance of the allogeneic engraftment, (ii) donor-specific anergy is induced in the cytotoxic T-lymphocytes of the recipients, (iii) T helper type 2 cells become the dominant T cells in the recipients that are accepting the skin transplants, and (iv) a lasting chimerism (microchimerism) is established in these recipients. This strategy, perhaps with minor modifications, might permit one also to overcome major barriers to organ allografting in humans. If this were the case, it could represent production of long lasting immunologic tolerance without need for irradiation or cytotoxic chemo-preparative regimen and as such could greatly facilitate allotransplantation free of episodes of chronic or acute rejection or toxic and damaging preparatory regimens.