Emiko Takeuchi

Allogenic mixed chimerism induced by nonlymphoablative regimen including donor BMT with low-dose TBI and anti-CD40L cured proliferative glomerulonephritis in lupus mice.

Abstract:  Allogeneic mixed chimerism achieved by low‐dose total body irradiation (TBI) and anti‐CD40L monoclonal antibody (mAb) with donor bone marrow transplantation (BMT) and host T cell depletion overcomes both allo‐ and autoimmunity. We investigated whether a similar regimen without T cell depletion cured diffuse proliferative glomerulonephritis. Male BXSB mice (H‐2b) were injected with 20 × 106 BALB/c (H‐2d) BM cells. When indicated, 3 Gy TBI on day –1 and anti‐CD40LmAb (2 mg) on day 0 of BMT was given. Skin grafting was performed 1 day after BMT. BXSB mice were divided into four groups—I: BMT with TBI and anti‐CD40LmAb; II: TBI; III: TBI and anti‐CD40LmAb; and IV: no treatment. Chimerism in peripheral blood was analyzed. The kidney was examined histologically. TBI with anti‐CD40LmAb and BMT allowed induction of multilineage mixed chimerism and donor‐specific tolerance to skin grafts without graft‐versus‐host disease (GVHD). There was significant decrease in glomerular PAS‐positive material deposition score, glomerular cell numbers, IgG, and C3 deposition in chimeric mice. All chimeric mice survived. Allogeneic mixed chimerism induced by a less toxic, nonlymphoablative regimen achieved allograft tolerance and cured glomerulonephritis in BXSB lupus mice.

Multiple allogeneic progenitors in combination function as a unit to support early transient hematopoiesis in transplantation

Combination of multiple units of allogeneic HSPCs exerts radioprotective and bridging effect, allowing single-donor hematopoiesis by a principal graft.

Cognate interaction plays a key role in the surveillance of autoreactive B cells in induced mixed bone marrow chimerism in BXSB lupus mice

The effects of bone marrow transplantation (BMT) as a treatment for and/or preventive measure against autoimmune diseases in mice were investigated extensively. The reconstitution of the hematopoietic system with a mixture of autologous and heterologous bone marrow cells was reported to suppress the development of autoimmune diseases. However, the pathological mechanism through which mixed chimerism results in the suppression of disease development is still unknown. We have previously reported that the induction of fully major histocompatibility complex (MHC)-mismatched allogeneic mixed chimerism can prevent the disease development in BXSB mice. Interestingly, serum anti-dsDNA IgM antibody (anti-DNA IgM) levels were not significantly decreased in these chimeric mice, though other symptoms of autoimmune disease were ameliorated. In this study, we showed that self-reactive anti-DNA IgM production was mainly attributable to genetically normal B cells from the donor rather than genetically deficient B cells from the host. Host-type B cells responded normally to foreign antigens and produced the appropriate antibodies. BMT from fully MHC-matched or haplo-identical donors could suppress the production of anti-DNA antibodies. Our present study suggests the existence of a surveillance system dependent on the recognition of MHC molecules on B cells.

Inhibitory function of NKT cells during early induction phase of nickel allergy.

Until now, metal allergies have been regarded as a Th1-type immune response.　However, because the contribution of a Th2-type immune response has been suggested by clinical findings, we previously examined the Th2-type immune response during the development of metal allergies using a GATA-3 transgenic (GATA-3 Tg) mouse model. As a result, a Th2-type immunization reaction was suggested to be involved in the early phase of metal allergies. Recently, the involvement of NKT cells in metal allergies has been suggested. We examined this possibility using the activation of NKT cells and an NKT cell-deficient mouse model to determine the contribution of NKT cells to nickel allergy in the present study. In NKT cell-deficient mice, ear swelling was remarkably increased, compared with that in control mice. Also, in mice that had been treated with α-galactosylceramide (α-GalCer) to activate NKT cells, the ear swelling response was remarkably inhibited, compared with that in untreated mice. These facts show that NKT cells are involved in the inhibition of nickel allergy-induced ear swelling responses.

Convenient Evaluation of Magnitude of Glomerulonephritis in BXSB/Mp Lupus Mice

Objective: Kidney involvement is one of the most important clinical features of systemic lupus erythematosus (SLE). Therefore, histopathological analysis of renal sections is necessary to evaluate the magnitude of lupus-like diseases. However, histopathological grading requires advanced pathological skills, otherwise the subjective views of the investigator can enter into evaluation. Here we show that in the case of a BXSB lupus mouse strain, the area and the long axis of glomeruli can be used as an objective index that can aid in the evaluation of the severity of lupus glomerulonephritis.Methods: Previously, we investigated the effects of treatment that involved the induction of bone marrow chimerism to BXSB lupus mice. Based on the results of histopathological analysis and immunofluorescence staining, the progression grades of lupus glomerulonephritis of seven experimental groups were decided. Then, we reevaluated the histopathological grade and the other elements of glomeruli in each experimental group. For the second examination, more than 30 glomeruli newly assessed on each section, and more than five sections from each group were analyzed. The area, long axis and short axis of all captured glomeruli were measured. The relationships between the histopathological score evaluated by two different pathologists, or between the mean histopathological scores and mean area and mean long/short axes of the glomeruli were analyzed using multiple linear regression.Results: There was a direct correlation between two scores that were reported by two different pathologists. Glomeruli with severe inflammatory exudates were found to be easy to grade correctly, while it was more difficult to differentiate thickening of mesangial cells. In contrast, the mean area and the mean axis of glomeruli had a high correlation to histopthological grade even in the low-grade stages of the disease, when minimal thickening or proliferative mesangial changes have occurred.Conclusion: The size of glomeruli correlates with the histopathlogical grade, especially the long axis of glomeruli, which is the easiest direction to measure. We thus conclude that this parameter can serve an auxiliary index of the severity of lupus glomerulonephritis in the BXSB lupus mouse strain.

Dysfunction of Selective Suppression of Auto-Antibody Production in SLE Mouse and Reconstruction of this Mechanism by Induction of Bone-Marrow Chimerism

Background: Mixed chimerism induced by hematopoietic stem cell transplantation is useful in the treatment of autoimmune diseases, but the details of the mechanism by which mixed chimerism reverses the autoimmune state have not been determined. Here, we propose a potential mechanism in which newly developed T cells positively selected by the recipient’s thymus are able to regulate auto-reactive B cells. To test this hypothesis, we investigated whether major histocompatibility complex (MHC)/T cell receptor (TCR) cognate interaction was important for the regulation of auto-reactive B cells. We induced an auto-cross-reactive Antibody (Ab) by immunization using a foreign antigen with a homolog to an auto-antigen in a BXSB lupus mouse strain and achieved MHC-matched or mismatched mixed chimerism. Methods: Stable multi-lineage mixed chimeric BXSB mice were established with non-lymphoablative conditioning. In order to induce auto-cross-reactive Ab, a foreign antigen Pigeon Cytochrome C (PCC) was immunized in these chimeric BXSB mice with various MHC combinations. Anti-PCC and anti-Mouse Cytochrome C (MCC: cross-reactive with PCC) Abs were measured by ELISA. Results: In normal mice and MHC-matched/haplo-identical chimeric mice, the titer of the anti-MCC Ab reached plateau at low levels. In BXSB and fully MHC-mismatched chimeric mice, however, both anti-PCC and MCC Ab levels were higher. Conclusion: These results suggest that the regulatory mechanism selectively suppresses auto-reactive Ab production through cognate interaction. Dysfunction of this suppression system is one possible cause of lupus; the induction of BM mixed chimerism may allow us to reconstruct the system.