Low levels of allogeneic but not syngeneic hematopoietic chimerism reverse autoimmune insulitis in prediabetic NOD mice

GPR41 deficiency aggravates type 1 diabetes in streptozotocin-treated mice by promoting dendritic cell maturation

Disturbances in intestinal immune homeostasis predispose susceptible individuals to type 1 diabetes (T1D). G-protein-coupled receptor 41 (GPR41) is a receptor for short-chain fatty acids (SCFAs) mainly produced by gut microbiota, which plays key roles in maintaining intestinal homeostasis. In this study, we investigated the role of GPR41 in the progression of T1D. In non-obese diabetic (NOD) mice, we found that aberrant reduction of GPR41 expression in the pancreas and colons was associated with the development of T1D. GPR41-deficient (Gpr41-/-) mice displayed significantly exacerbated streptozotocin (STZ)-induced T1D compared to wild-type mice. Furthermore, Gpr41-/- mice showed enhanced gut immune dysregulation and increased migration of gut-primed IFN-γ+ T cells to the pancreas. In bone marrow-derived dendritic cells from Gpr41-/- mice, the expression of suppressor of cytokine signaling 3 (SOCS) was significantly inhibited, while the phosphorylation of STAT3 was significantly increased, thus promoting dendritic cell (DC) maturation. Furthermore, adoptive transfer of bone marrow-derived dendritic cells (BMDC) from Gpr41-/- mice accelerated T1D in irradiated NOD mice. We conclude that GPR41 is essential for maintaining intestinal and pancreatic immune homeostasis and acts as a negative regulator of DC maturation in T1D. GPR41 may be a potential therapeutic target for T1D.

Biomedical Applications of Translational Optical Imaging: From Molecules to Humans

Light is a powerful investigational tool in biomedicine, at all levels of structural organization. Its multitude of features (intensity, wavelength, polarization, interference, coherence, timing, non-linear absorption, and even interactions with itself) able to create contrast, and thus images that detail the makeup and functioning of the living state can and should be combined for maximum effect, especially if one seeks simultaneously high spatiotemporal resolution and discrimination ability within a living organism. The resulting high relevance should be directed towards a better understanding, detection of abnormalities, and ultimately cogent, precise, and effective intervention. The new optical methods and their combinations needed to address modern surgery in the operating room of the future, and major diseases such as cancer and neurodegeneration are reviewed here, with emphasis on our own work and highlighting selected applications focusing on quantitation, early detection, treatment assessment, and clinical relevance, and more generally matching the quality of the optical detection approach to the complexity of the disease. This should provide guidance for future advanced theranostics, emphasizing a tighter coupling-spatially and temporally-between detection, diagnosis, and treatment, in the hope that technologic sophistication such as that of a Mars rover can be translationally deployed in the clinic, for saving and improving lives.

Stem cells to restore insulin production and cure diabetes

BACKGROUND

The advancement of knowledge in the field of regenerative medicine is increasing the therapeutic expectations of patients and clinicians on cell therapy approaches. Within these, stem cell therapies are often evoked as a possible therapeutic option for diabetes, already ongoing or possible in the near future.

AIM

The purpose of this document is to make a point of the situation on existing knowledge and therapies with stem cells to treat patients with diabetes by focusing on some of the aspects that most frequently raise curiosity and discussion in clinical practice and in the interaction with the patient. In fact, at present there are no clinically approved treatments based on the use of stem cells for the treatment of diabetes, but several therapeutic approaches have already been evaluated or are being evaluated in clinical trials.

DATA SYNTHESIS

It is possible to identify three large potential application fields: 1) the reconstruction of the β cell mass; 2) the immunomodulation in type 1 diabetes (T1D); 3) the treatment of complications. In this study we will limit the discussion to approaches that have the potential for clinical translation, deliberately omitting aspects of basic biology and preclinical data. Also, we intentionally omit the treatment of the complications that will be the subject of a future document. Finally, an overview of the Italian situation regarding the storage of cord blood cells for the therapy of diabetes will be given.

Lymphopenia is detrimental to therapeutic approaches to type 1 diabetes using regulatory T cells

One of the therapeutic approaches to type 1 diabetes (T1D) focuses on enhancement of regulatory T cell (Treg) activity, either by adoptive transfer or supplementation of supporting cytokines such as interleukin-2 (IL-2). In principle, this therapeutic design would greatly benefit of concomitant reduction in pathogenic cell burden. Experimental evidence indicates that physiological recovery from lymphopenia is dominated by evolution of effector and cytotoxic cells, which abolishes the therapeutic efficacy of Treg cells. Targeted and selective depletion of effector T cells has been achieved with killer Treg using Fas ligand protein and a fusion protein composed of IL-2 and caspase-3, which showed remarkable efficacy in modulating the course of inflammatory insulitis in NOD mice. We emphasize a critical consideration in design of therapeutic approaches to T1D, immunomodulation without lymphoreduction to avoid the detrimental consequences of rebound recovery from lymphopenia.

Engineering of bone marrow cells with fas-ligand protein-enhances donor-specific tolerance to solid organs

Effective immunomodulation to induce tolerance to tissue/organ allografts is attained by infusion of donor lymphocytes endowed with killing capacity through ectopic expression of a short-lived Fas-ligand (FasL) protein. The same approach has proven effective in improving hematopoietic stem and progenitor cell engraftment. This study evaluates the possibility of substitution of immune cells for bone marrow cells (BMC) to induce FasL-mediated tolerance to solid organ grafts. Expression of FasL protein on BMC increased the survival of simultaneously grafted vascularized heterotopic cardiac grafts to 90%, as compared to 30% in recipients of naïve BMC. Similar results were obtained for skin allografts implanted into radiation chimeras at 1 week after bone marrow transplantation. Further reduction of preparative conditioning to busulfan resulted in acceptance of donor skin implanted at 2 weeks after transplantation of naïve and FasL-coated BMC, whereas third-party grafts were acutely rejected. The levels of donor chimerism were in the range of 0.7% to 12% at the time of skin grafting, with higher levels in recipients of FasL-coated BMC. It is concluded that FasL-mediated abrogation of alloimmune responses can be effectively attained with BMC. There is no threshold of donor chimerism, but tolerance to solid organs evolves during the process of donor-host mutual acceptance.

Two distinct mechanisms mediate the involvement of bone marrow cells in islet remodeling: neogenesis of insulin-producing cells and support of islet recovery

We have recently reported that small-sized bone marrow cells (BMCs) isolated by counterflow centrifugal elutriation and depleted of lineage markers (Fr25lin(-)) have the capacity to differentiate and contribute to regeneration of injured islets. In this study, we assess some of the characteristics of these cells compared to elutriated hematopoietic progenitors (R/O) and whole BMCs in a murine model of streptozotocin-induced chemical diabetes. The GFP(bright)CD45(+) progeny of whole BMCs and R/O progenitors progressively infiltrate the pancreas with evolution of donor chimerism; are found at islet perimeter, vascular, and ductal walls; and have a modest impact on islet recovery from injury. In contrast, Fr25lin(-) cells incorporate in the islets, convert to GFP(dim)CD45(-)PDX-1(+) phenotypes, produce proinsulin, and secrete insulin with significant contribution to stabilization of glucose homeostasis. The elutriated Fr25lin(-) cells express low levels of CD45 and are negative for SCA-1 and c-kit, as removal of cells expressing these markers did not impair conversion to produce insulin. BMCs mediate two synergistic mechanisms that contribute to islet recovery from injury: support of islet remodeling by hematopoietic cells and neogenesis of insulin-producing cells from stem cells.

Surge in regulatory T cells does not prevent onset of hyperglycemia in NOD mice: immune profiles do not correlate with disease severity

Immune profiling of non-obese diabetic (NOD) is a widely employed tool to assess the mechanisms of inflammatory insulitis. Our analysis of the female NOD colony revealed similar distribution of lymphoid lineages to wild type mice, and at various ages of prediabetic and diabetic mice. The profiles of mesenteric and pancreatic lymph nodes differ and often change reciprocally due to directed migration of T cells towards the site of inflammation. Significant events in our colony include early decline in CD4(+)CD25(+)CD62L(+) Treg, accompanied by gradual increase in CD4(+)CD25(+)FoxP3(+) Treg in peripheral lymphoid organs and pancreatic infiltrates. Impressively, aged euglycemic mice display significant transient rise in CD4(+)CD25(-)FoxP3(+) Treg in the thymus, pancreas and draining lymph nodes. A significant difference was superior viability of effector and suppressor cells from new onset diabetics in the presence of high interleukin-2 (IL-2) concentrations in vitro as compared to cells of prediabetic mice. Overall, we found no correlation between FoxP3(+) Treg in the pancreatic lymph nodes and the inflammatory scores of individual NOD mice. CD25(-)FoxP3(+) Treg are markedly increased in the pancreatic infiltrates in late stages of inflammation, possibly an effort to counteract destructive insulitis. Considering extensive evidence that Treg in aged NOD mice are functionally sufficient, quantitative profiling evolves as an unreliable tool to assess mechanism and causes of inflammation under baseline conditions. Immune profiles are modulated by thymic output, cell migration, shedding of markers, proliferation, survival and in-situ evolution of regulatory cells.

Early immunisation with dendritic cells after allogeneic bone marrow transplantation elicits graft vs tumour reactivity

Background:

Perspectives of immunotherapy to cancer mediated by bone marrow transplantation (BMT) in conjunction with dendritic cell (DC)-mediated immune sensitisation have yielded modest success so far. In this study, we assessed the impact of DC on graft vs tumour (GvT) reactions triggered by allogeneic BMT.

Methods:

H2K^a mice implanted with congenic subcutaneous Neuro-2a neuroblastoma (NB, H2K^a) tumours were irradiated and grafted with allogeneic H2K^b bone marrow cells (BMC) followed by immunisation with tumour-inexperienced or tumour-pulsed DC.

Results:

Immunisation with tumour-pulsed donor DC after allogeneic BMT suppressed tumour growth through induction of T cell-mediated NB cell lysis. Early post-transplant administration of DC was more effective than delayed immunisation, with similar efficacy of DC inoculated into the tumour and intravenously. In addition, tumour inexperienced DC were equally effective as tumour-pulsed DC in suppression of tumour growth. Immunisation of DC did not impact quantitative immune reconstitution, however, it enhanced T-cell maturation as evident from interferon-γ (IFN-γ) secretion, proliferation in response to mitogenic stimulation and tumour cell lysis in vitro. Dendritic cells potentiate GvT reactivity both through activation of T cells and specific sensitisation against tumour antigens. We found that during pulsing with tumour lysate DC also elaborate a factor that selectively inhibits lymphocyte proliferation, which is however abolished by humoral and DC-mediated lymphocyte activation.

Conclusion:

These data reveal complex involvement of antigen-presenting cells in GvT reactions, suggesting that the limited success in clinical application is not a result of limited efficacy but suboptimal implementation. Although DC can amplify soluble signals from NB lysates that inhibit lymphocyte proliferation, early administration of DC is a dominant factor in suppression of tumour growth.

Reappraisal of total body irradiation followed by bone marrow transplantation as a therapy for inflammatory bowel disease

The main current therapies for inflammatory bowel diseases (IBD) are aimed at controlling the exacerbated inflammation in the gut. Although these therapies have been successful, they are not curative and it is not possible to predict whether a beneficial response will occur or which patients will be refractory to the treatment. Total body irradiation (TBI) associated with chemotherapy is the first choice in the treatment of some hematological disorders and is an applicable option in the preparation of patients with hematologic diseases for hematopoietic stem cell transplantation. Then, in this study we investigated the association of TBI as immunosuppressive therapy and bone marrow cell (BMC) transplantation as a strategy to induce colitis recovery and immune reconstitution in the TNBS model of intestinal inflammation. TNBS mice treated with TBI associated with BMC transplantation presented elevated gain of weight and an overall better outcome of the disease when compared to those treated only with TBI. In addition, TBI associated or not with BMC reduced the frequency of inflammatory cells in the gut and restored the goblet cell counts. These results were accompanied by a down regulation in the production of inflammatory cytokines in the colon of mice treated with TBI alone or in association with BMC transplantation. The BMC infused were able to repopulate the ablated immune system and accumulate in the site of inflammation. However, although both treatments (TBI or TBI+BMC) were able to reduce gut inflammation, TBI alone was not enough to fully restore mice weight and these animals presented an extremely reduced survival rate when their immune system was not promptly reconstituted with BMC transplantation. Finally, these evidences suggest that the BMC transplantation is an efficient strategy to reduce the harmful effects of TBI in the colitis treatment, suggesting that radiotherapy may be an important immunosuppressive therapy in patients with IBD, by modulating the local inflammatory response.

Mesenchymal stem cells facilitate mixed hematopoietic chimerism induction and prevent onset of diabetes in nonobese diabetic mice

OBJECTIVES

Allogeneic mesenchymal stem cells (MSCs) and bone marrow cells (BMCs) were cotransplanted in nonobese diabetic mice after none myeloablative preconditioning and the development of chimerism, insulitis, diabetes, and graft-versus-host disease (GVHD) were monitored.

METHODS

Eight-week-old female nonobese diabetic mice were injected intravenously with 2 × 10 BMCs and 5 × 10 MSCs from C57BL/6 mice after treatment with 2 intraperitoneal injections of anti-CD3 antibody (days -7 and -4) and 3-Gy total body irradiation (day -1). Thereafter, blood glucose and chimerism were monitored on peripheral blood samples.

RESULTS

Stable mixed chimerism (3->90% of donor phenotype) was induced in 63.2% of BMCs-MSCs recipients (n = 19) and 45.0% of BMCs-alone recipients (n = 20, P = 0.256). Insulitis was prevented, and euglycemia persisted for more than 18 weeks in 89.5% of BMCs-MSCs recipients including those with less than 3% chimerism and 55% of BM-alone recipients (P < 0.05). In controls, 9.1% of mice receiving preconditioning treatment alone (n = 11) and 16.7% of preconditioned mice receiving only MSCs (n = 12) were nondiabetic. Graft-versus-host disease was not detected in all mice.

CONCLUSIONS

Coinjection of MSCs and BMCs increased the success rate in inducing chimerism and preventing insulitis and overt diabetes with no incidence of GVHD. Results also indicated that even microchimerism with less than 3% donor cells is sufficient for blocking autoimmunity.

Bone marrow transplantation combined with mesenchymal stem cells induces immune tolerance without cytotoxic conditioning

BACKGROUND

Transplantation of allogeneic donor bone marrow (BM) into sufficiently conditioned recipients is an effective approach to induce immune tolerance as assessed by mixed chimerism. However, this approach is hampered by the lack of feasible protocols devoid of cytoreductive conditioning. We investigated whether mixed chimerism could be established by intra-bone marrow-bone marrow transplantation (IBM-BMT) combined with bone marrow-derived mesenchymal stem cells (BMSCs) treatment without additional cytoreductive conditioning.

MATERIALS AND METHODS

The recipient mice (C57BL/6) accepted BMSCs from donor mice (Balb/c) through daily tail vein injection for 4 d followed by IBM-BMT immediately. Full-thickness skin grafts from donor mice as well as from the third party mice (ICR) were transplanted to the dorsum of the recipient mice after the combined IBM-BMT with BMSCs treatment. The immune tolerance was assessed by the survival time of skin allografts. The establishment of mixed chimerism and cytokine expression profile in recipient peripheral blood were determined by flow cytometry and enzyme-linked immunosorbent assay, respectively.

RESULTS

IBM-BMT combined with BMSCs treatment led to stable mixed chimerism and donor-specific skin graft tolerance. The flow cytometry analysis revealed that recipient mice developed 20%-25% chimerism levels among the myeloid lineage. The skin allografts survived more than 1 y and the hair re-grew normally on the grafts. Cytokine profile showed that IBM-BMT combined with BMSCs treatment prolonged humoral tolerance in recipient chimeras.

CONCLUSIONS

Our results demonstrate that donor specific immune tolerance can be effectively induced by IBM-BMT combined with BMSCs treatment without any additional cytoreductive recipient treatment. This approach provides a promising allograft transplantation strategy when the donor bone marrow is available.

Effector and naturally occurring regulatory T cells display no abnormalities in activation induced cell death in NOD mice

Background

Disturbed peripheral negative regulation might contribute to evolution of autoimmune insulitis in type 1 diabetes. This study evaluates the sensitivity of naïve/effector (Teff) and regulatory T cells (Treg) to activation-induced cell death mediated by Fas cross-linking in NOD and wild-type mice.

Principal Findings

Both effector (CD25⁻, FoxP3⁻) and suppressor (CD25⁺, FoxP3⁺) CD4⁺ T cells are negatively regulated by Fas cross-linking in mixed splenocyte populations of NOD, wild type mice and FoxP3-GFP tranegenes. Proliferation rates and sensitivity to Fas cross-linking are dissociated in Treg cells: fast cycling induced by IL-2 and CD3/CD28 stimulation improve Treg resistance to Fas-ligand (FasL) in both strains. The effector and suppressor CD4⁺ subsets display balanced sensitivity to negative regulation under baseline conditions, IL-2 and CD3/CD28 stimulation, indicating that stimulation does not perturb immune homeostasis in NOD mice. Effective autocrine apoptosis of diabetogenic cells was evident from delayed onset and reduced incidence of adoptive disease transfer into NOD.SCID by CD4⁺CD25⁻ T cells decorated with FasL protein. Treg resistant to Fas-mediated apoptosis retain suppressive activity in vitro. The only detectable differential response was reduced Teff proliferation and upregulation of CD25 following CD3-activation in NOD mice.

Conclusion

These data document negative regulation of effector and suppressor cells by Fas cross-linking and dissociation between sensitivity to apoptosis and proliferation in stimulated Treg. There is no evidence that perturbed AICD in NOD mice initiates or promotes autoimmune insulitis.

Reinterpretation of evidence advanced for neo-oogenesis in mammals, in terms of a finite oocyte reserve

The central tenet of ovarian biology, that the oocyte reserve in adult female mammals is finite, has been challenged over recent years by proponents of neo-oogenesis, who claim that germline stem cells exist in the ovarian surface epithelium or the bone marrow. Currently opinion is divided over these claims, and further scrutiny of the evidence advanced in support of the neo-oogenesis hypothesis is warranted - especially in view of the enormous implications for female fertility and health. This article contributes arguments against the hypothesis, providing alternative explanations for key observations, based on published data. Specifically, DNA synthesis in germ cells in the postnatal mouse ovary is attributed to mitochondrial genome replication, and to DNA repair in oocytes lagging in meiotic progression. Lines purported to consist of germline stem cells are identified as ovarian epithelium or as oogonia, from which cultures have been derived previously. Effects of ovotoxic treatments are found to negate claims for the existence of germline stem cells. And arguments are presented for the misidentification of ovarian somatic cells as de novo oocytes. These clarifications, if correct, undermine the concept that germline stem cells supplement the oocyte quota in the postnatal ovary; and instead comply with the theory of a fixed, unregenerated reserve. It is proposed that acceptance of the neo-oogenesis hypothesis is erroneous, and may effectively impede research in areas of ovarian biology. To illustrate, a novel explanation that is consistent with orthodox theory is provided for the observed restoration of fertility in chemotherapy-treated female mice following bone marrow transplantation, otherwise interpreted by proponents of neo-oogenesis as involving stimulation of endogenous germline stem cells. Instead, it is proposed that the chemotherapeutic regimens induce autoimmunity to ovarian antigens, and that the haematopoietic chimaerism produced by bone marrow transplantation circumvents activation of an autoreactive response, thereby rescuing ovarian function. The suggested mechanism draws from animal models of autoimmune ovarian disease, which implicate dysregulation of T cell regulatory function; and from a surmised role for follicular apoptosis in the provision of ovarian autoantigens, to sustain self-tolerance during homeostasis. This interpretation has direct implications for fertility preservation in women undergoing chemotherapy.

Immunomodulation with dendritic cells and donor lymphocyte infusion converge to induce graft vs neuroblastoma reactions without GVHD after allogeneic bone marrow transplantation

BACKGROUND

Mounting evidence points to the efficacy of donor lymphocyte infusion (DLI) and immunisation with tumour-pulsed dendritic cells (DC) in generating graft vs leukaemia reactions after allogeneic bone marrow transplantation (BMT). We assessed the efficacy of DLI and DC in generating potent graft vs neuroblastoma tumour (GVT) reactions following allogeneic BMT.

METHODS

Mice bearing congenic (H2K(a)) Neuro-2a tumours were grafted with allogeneic (H2K(b)) T-cell-depleted bone marrow cells. Tumour-pulsed donor DC (DC(Neuro2a)) were inoculated (on day +7) in conjunction with donor (H2K(b)) and haploidentical (H2K(a/b)) lymphocytes.

RESULTS

Murine Neuro-2a cells elicit immune reactions as efficient as B lymphoma in major histocompatibility complex antigen-disparate mice. Lymphopenia induced by conditioning facilitates GVT, and transition to adaptive immunity is enhanced by simultaneous infusion of and DC(Neuro2a) and lymphocytes devoid of graft vs host (GVH) activity (H2K(a/b)). In variance, the efficacy of DC-mediated immunomodulation was diminished by severe graft vs host disease (GVHD), showing mechanistic dissociation and antagonising potential to GVT.

CONCLUSIONS

The GVHD is not a prerequisite to induce GVT reactivity after allogeneic BMT, but is rather detrimental to induction of anti-tumour immunity by DC-mediated immunomodulation. Simultaneous inoculation of tumour-pulsed donor DC and DLI synergise in stimulation of potent GVT reactions to the extent of eradication of established NB tumours.

Immunosuppressive therapy exacerbates autoimmunity in NOD mice and diminishes the protective activity of regulatory T cells

Mounting evidence indicates that immunosuppressive therapy and autologous bone marrow transplantation are relatively inefficient approaches to treat autoimmune diabetes. In this study we assessed the impact of immunosuppression on inflammatory insulitis in NOD mice, and the effect of radiation on immunomodulation mediated by adoptive transfer of various cell subsets. Sublethal radiation of NOD females at the age of 14 weeks (onset of hyperglycemia) delayed the onset of hyperglycemia, however two thirds of the mice became diabetic. Adoptive transfer of splenocytes into irradiated NON and NOD mice precipitated disease onset despite increased contents of CD25(+)FoxP3(+) T cells in the pancreas and regional lymphatics. Similar phenotypic changes were observed when CD25(+) T cells were infused after radiation, which also delayed disease onset without affecting its incidence. Importantly, irradiation increased the susceptibility to diabetes in NOD and NON mice (71-84%) as compared to immunomodulation with splenocytes and CD25(+) T cells in naïve recipients (44-50%). Although irradiation had significant and durable influence on pancreatic infiltrates and the fractions of functional CD25(+)FoxP3(+) Treg cells were elevated by adoptive cell transfer, this approach conferred no protection from disease progression. Irradiation was ineffective both in debulking of pathogenic clones and in restoring immune homeostasis, and the consequent homeostatic expansion evolves as an unfavorable factor in attempts to restore self-tolerance and might even provoke uncontrolled proliferation of pathogenic clones. The obstacles imposed by immunosuppression on abrogation of autoimmune insulitis require replacement of non-specific immunosuppressive therapy by selective immunomodulation that does not cause lymphopenia.

Allogeneic stem cell transplantation for rheumatic autoimmune diseases

Haematopoietic stem cell transplantation (HSCT) has evolved from an experimental concept to an effective treatment option for severe autoimmune diseases and has a unique ability to restore immune regulation. It is a complex multistep procedure involving the administration of high doses of immunosuppressive medication and transplantation of stem cells. Most HSCT procedures in autoimmune disease have involved autologous stem cells. In the case of allogeneic transplantation, stem cells are derived from peripheral blood or bone marrow of a healthy HLA-matched donor. Allogeneic HSCT has curative potential based on studies in experimental models of autoimmune disease, case reports, and a registry analysis but carries significant risks of rejection and graft-versus-host disease. Unless these risks become manageable, allogeneic HSCT should be offered only if all alternative treatment options have failed, if a patient has a suitable donor, and if a patient still has a chance to benefit significantly from the procedure.

Hematopoietic SCT modulates gut inflammation in experimental inflammatory bowel disease

Hematopoietic SCT (HSCT) and high-dose chemotherapy are being explored as therapy for various human refractory immune-mediated conditions, including inflammatory bowel diseases (IBD). Nevertheless, the exact immunological mechanisms by which the BM cells (BMCs) or immunosuppression provide remission from these diseases is not yet clear. In this work, we investigated the role of these therapies in the modulation of gut mucosal inflammation in an experimental model of IBD. Colitis was induced in mice by 2,4,6-trinitrobenzenesulfonic acid and after CY was administered (200 mg/kg) alone (CY group) or followed by BMCs infusion (HSCT group). Animals were followed for 60 days. Both HSCT and CY reduced the histopathological features of colitis significantly. Infused cells were localized in the gut, and a marked decrease of CD4(+) leukocytes in the inflammatory infiltrate on days +7 and +14 and of CD8(+) cells on day +7 was found in both treatments allied to impressive reduction of proinflammatory Th1 and Th17 cytokines. Although chemotherapy alone was the best treatment regarding the induction of immunosuppressive molecules, only HSCT resulted in increased survival rates compared with the control group. Our findings indicate that high-dose CY followed by HSCT is effective in the modulation of mucosal immunity and in accelerating immune reconstitution after BMT, thus providing valuable tools to support the development and understanding of novel therapeutic strategies for IBD.

Transfusion of nonobese diabetic mice with allogeneic newborn blood ameliorates autoimmune diabetes and modifies the expression of selected immune response genes

Although allogeneic bone marrow transplantation has been shown to prevent autoimmune diabetes in heavily irradiated nonobese diabetic (NOD) mice, a similar procedure is not suitable for the treatment of patients with type 1 diabetes because of associated severe side effects. Therefore, we evaluated whether mouse newborn blood (NBB), equivalent to human umbilical cord blood, could be used for diabetes prevention without recipient preconditioning. To test this hypothesis, unconditioned, prediabetic female NOD mice were given a single injection of whole NBB derived from the allogeneic diabetes-resistant mouse strain C57BL/6. Transfusion of allogeneic NBB but not adult blood prevented diabetes incidence in a majority of treated mice for a prolonged period of time. This was accompanied by the release of insulin in response to a challenge with glucose. Invasive cellular infiltration of islets was also substantially reduced in these mice. Although NBB transfusion induced a low level of hematopoietic microchimerism, it did not strictly correlate with amelioration of diabetes. Induction of genes implicated in diabetes, such as Il18, Tnfa, and Inos but not Il4, Il17 or Ifng, was repressed in splenocytes derived from protected mice. Notably, expression of the transcription factor Tbet/Tbx21 but not Gata3 or Rorgt was upregulated in protected mice. These data indicate that allogeneic NBB transfusion can prevent diabetes in NOD mice associated with modulation of selected cytokine genes implicated in diabetes manifestation. The data presented in this study provide the proof of principle for the utility of allogeneic umbilical cord blood transfusion to treat patients with autoimmune diabetes.

Targeting of IL-2 receptor with a caspase fusion protein disrupts autoimmunity in prediabetic and diabetic NOD mice

AIMS/HYPOTHESIS

Interruption of IL-2 signalling is an attractive therapeutic target in autoimmune disorders. In this study we evaluated the effect of a fusion protein composed of IL-2 and caspase-3 (IL2-cas) on NOD mice, as compared with disease induction by cyclophosphamide.

METHODS

IL2-cas was assessed in NOD mice at various ages and in conjunction with cyclophosphamide administration. The effect of IL2-cas on diabetogenic cells was evaluated in adoptive transfer experiments and in cell suspension in vitro.

RESULTS

IL2-cas induced apoptosis in T cells expressing the alpha chain of the IL-2 receptor (cluster of differentiation [CD]25) in vitro, with superior survival of T cells expressing CD4 and forkhead box P3 (FOXP3). The fusion protein decreased mixed lymphocyte reactivity, and pretreatment with IL2-cas decreased the efficacy of adoptive transfer of diabetes into NOD severe combined immunodeficiency mice. Administration of one dose of IL2-cas decreased the incidence of diabetes in NOD mice, showing a superior beneficial effect when administered at young age, and effectively blocked induction of hyperglycaemia by cyclophosphamide, reducing the severity of islet inflammation. Administration of IL2-cas caused an acute increase in CD25(-)FOXP3(+) T cells in the lymph nodes, pancreas and thymus in NOD mice, with similar effects in wild-type mice. Administration of IL2-cas after onset of hyperglycaemia resulted in superior survival.

CONCLUSIONS/INTERPRETATION

Targeted elimination of cells expressing the IL-2 receptor by this fusion protein disrupts the autoimmune pathogenesis in prediabetic and diabetic NOD mice, despite depletion of CD25(+) regulatory T cells. Furthermore, this particular fusion protein is permissive to the development of FOXP3(+) T cells that might contribute to protracted protection from the progression of insulitis and overt hyperglycaemia.

Consideration of strategies for hematopoietic cell transplantation

Bone marrow transplantation has been adoptively transferred from oncology to the treatment of autoimmune disorders. Along with extension of prevalent transplant-related concepts, the assumed mechanism that arrests autoimmunity involves elimination of pathogenic cells and resetting of immune homeostasis. Similar to graft versus tumor (GVT) reactivity, allogeneic transplants are considered to provide a better platform of immunomodulation to induce a graft versus autoimmunity reaction (GVA). It is yet unclear whether recurrence of autoimmunity in both autologous and allogeneic settings reflects relapse of the disease, transplant-associated immune dysfunction or insufficient immune modulation. Possible causes of disease recurrence include reactivation of residual host pathogenic cells and persistence of memory cells, genetic predisposition to autoimmunity and pro-inflammatory characteristics of the target tissues. Most important, there is little evidence that autoimmune disorders are indeed abrogated by current transplant procedures, despite reinstitution of both peripheral and thymic immune homeostasis. It is postulated that non-specific immunosuppressive therapy that precedes and accompanies current bone marrow transplant strategies is detrimental to the active immune process that restores self-tolerance. This proposition refocuses the need to develop strategies of immunomodulation without immunosuppression.