Overall Goals for Treatment of T1D
Tomei lab research pictures throughout these years
Current Projects
Conformal islet encapsulation for transplantation at vascularized sites to allow physiological insulin secretion
2R01DK109929 Tomei (PI)
Type 1 diabetes is an autoimmune disease that leads to selective destruction of insulin-secreting pancreatic b cells and lifelong dependence on exogenous insulin supplementation. In the United States, type 1 diabetes affects 1.84 million people, increased 21% in diagnosis between 2001 and 2009, and is projected to affect 5 million people by 2050. Allogeneic b cell replacement through intrahepatic islet transplantation leads to improved metabolic control, quality of life, and decreased levels of long-term complications in patients with type 1 diabetes compared to exogenous insulin supplementation. This is largely due to the capability of transplanted islets to re-establish physiological glucose-stimulated insulin secretion. Recent clinical advances in islet transplantation have increased the hope of the millions of patients with type 1 diabetes for a widely available cure. However, all this progress notwithstanding, the need for chronic systemic immunosuppression to prevent allorejection and recurrence of autoimmunity is still restricting the applicability of b cell replacement procedures only to the most severe cases of type 1 diabetes due to the multitude of unavoidable side effects.
Islet immunoisolation through encapsulation with permselective biomaterials is a viable option to allow safer and more widely applicable b cell replacement for patients with type 1 diabetes. The main challenges associated with transplantation of encapsulated islets are (1) their large capsule size, which delays glucose sensing and insulin release and results in an inability to achieve the same level of metabolic control as that provided by unencapsulated islets, and (2) their large graft volumes, which prevent transplantation in retrievable, confined, and well-vascularized sites. We developed an innovative microencapsulation platform that achieves conformal coating of islets, including ones derived from stem cells, within biocompatible, stable, and clinically applicable hydrogels that are only 10-20 µm thick. This conformal coating addresses limitations of traditional islet encapsulation platforms and safety as demonstrated in non-human primate models of type 1 diabetes. However, conformally coated grafts are still hindered by alloreactive T cell activation by alloantigen shedding through permeable hydrogel capsules and can benefit from localized immunomodulatory therapies to improve their performance for clinical translation. Thus, we propose to co-transplant them with our innovative nanomaterial platform to achieve targeted and sustained release of drugs that decrease alloreactive T cell activation in the site of transplantation (aim 1). As an alternative and innovative approach, we also propose to integrate islet conformal coating with co-delivery of tolerogenic stromal cells that can present shed alloantigens to specific T cells, thereby inducing anergy and deletion in the transplant site (aim 2). We will test these combination therapies in murine and rat islet allograft models of type 1 diabetes in clinically applicable confined sites, uniquely enabled by the small volumes of conformal coated grafts in aims 1 and 2. In aim 3, we will test the most promising immunomodulatory approach in non-human primate islet allograft models and with human islets in a humanized mouse model.
2R01DK109929 Tomei (PI)
Type 1 diabetes is an autoimmune disease that leads to selective destruction of insulin-secreting pancreatic b cells and lifelong dependence on exogenous insulin supplementation. In the United States, type 1 diabetes affects 1.84 million people, increased 21% in diagnosis between 2001 and 2009, and is projected to affect 5 million people by 2050. Allogeneic b cell replacement through intrahepatic islet transplantation leads to improved metabolic control, quality of life, and decreased levels of long-term complications in patients with type 1 diabetes compared to exogenous insulin supplementation. This is largely due to the capability of transplanted islets to re-establish physiological glucose-stimulated insulin secretion. Recent clinical advances in islet transplantation have increased the hope of the millions of patients with type 1 diabetes for a widely available cure. However, all this progress notwithstanding, the need for chronic systemic immunosuppression to prevent allorejection and recurrence of autoimmunity is still restricting the applicability of b cell replacement procedures only to the most severe cases of type 1 diabetes due to the multitude of unavoidable side effects.
Islet immunoisolation through encapsulation with permselective biomaterials is a viable option to allow safer and more widely applicable b cell replacement for patients with type 1 diabetes. The main challenges associated with transplantation of encapsulated islets are (1) their large capsule size, which delays glucose sensing and insulin release and results in an inability to achieve the same level of metabolic control as that provided by unencapsulated islets, and (2) their large graft volumes, which prevent transplantation in retrievable, confined, and well-vascularized sites. We developed an innovative microencapsulation platform that achieves conformal coating of islets, including ones derived from stem cells, within biocompatible, stable, and clinically applicable hydrogels that are only 10-20 µm thick. This conformal coating addresses limitations of traditional islet encapsulation platforms and safety as demonstrated in non-human primate models of type 1 diabetes. However, conformally coated grafts are still hindered by alloreactive T cell activation by alloantigen shedding through permeable hydrogel capsules and can benefit from localized immunomodulatory therapies to improve their performance for clinical translation. Thus, we propose to co-transplant them with our innovative nanomaterial platform to achieve targeted and sustained release of drugs that decrease alloreactive T cell activation in the site of transplantation (aim 1). As an alternative and innovative approach, we also propose to integrate islet conformal coating with co-delivery of tolerogenic stromal cells that can present shed alloantigens to specific T cells, thereby inducing anergy and deletion in the transplant site (aim 2). We will test these combination therapies in murine and rat islet allograft models of type 1 diabetes in clinically applicable confined sites, uniquely enabled by the small volumes of conformal coated grafts in aims 1 and 2. In aim 3, we will test the most promising immunomodulatory approach in non-human primate islet allograft models and with human islets in a humanized mouse model.
Localized delivery of costimulatory inhibitors and tolerogenic stromal cells for targeted immunomodulation in beta cell replacement
3-SRA-2024-1477-S-B Tomei (PI)
Type 1 diabetes (T1D) is an autoimmune disease that leads to selective destruction of insulin-secreting pancreatic β cells and lifelong dependence on exogenous insulin supplementation. In the US, 1.84 million people have T1D and 5 million people are expected to be diagnosed by 2050. Allogeneic β cell replacement through intrahepatic islet transplantation leads to better metabolic control, fewer long-term complications, and improved quality of life in patients with T1D as compared to exogenous insulin supplementation. The field of β cell replacement has recently benefited from major progress that addressed several limitations of the procedure for treatment of T1D. These recent advances have increased the hope of the millions of patients with T1D for a widely available cure. However, the continuing need for chronic systemic immunosuppression to prevent allorejection and recurrence of autoimmunity restricts the application of β cell replacement to the most severe cases of T1D due to a multitude of unavoidable side effects. Different strategies have been tested to achieve safer and more widely applicable β cell replacement for patients with T1D. Localized immunomodulation in the islet graft is enabled by extrahepatic transplantation in clinically-applicable confined sites such as the omental, intramuscular, and the subcutaneous sites. The clinically approved co-stimulation blocker abatacept (CTLA4Ig, human IgG1 subclass) blocks CD80/86 signaling required for T cell activation and promotes allograft survival in both preclinical models and in patients. Similarly, anti-CD40L antibodies were also effective in preclinical and clinical settings. However, systemic injection of these co-stimulatory blocking antibodies and immunomodulatory biologics in general is associated with adverse effects. This shortcoming can be addressed by non-systemic, localized, sustained delivery. Alternative to local immunosuppression, co-delivery of islets with immunomodulatory cells has demonstrated beneficial effects in islet transplantation by decreasing the need for systemic immunosuppression and inducing tolerance. Co-transplantation with tolerogenic non-professional stromal antigen-presenting fibroblastic reticular cells (FRCs) can also decrease alloreactive T cell activation and promote long-term allograft survival. These cells are a subpopulation of lymph node stromal cells that play key roles in peripheral tolerance through different mechanisms. We demonstrated that FRCs can present selected antigens to specific T cells inducing anergy and regulation in vitro. We hypothesize that localized and sustained release of selected human IgG1-based co-stimulatory blocking biologics by human IgG1-capturing degradable hydrogels co-delivered with islets in a confined site will prevent alloreactive T cell activation to prolong allograft survival in mice (aim 1). We also hypothesize that co-transplantation of pre-conditioned, antigen-primed, syngeneic fibroblastic reticular cells alongside allogeneic cells will decrease activation and tolerize recipient alloreactive T cells to improve murine allograft survival (aim 2). In aim 1, we will optimize the design of biologics-binding degradable hydrogels to provide sustained release of abatacept and anti-CD40L and test therapeutic efficacy in vitro and in vivo in murine allograft models. We will determine the dose of IgG1-binding peptide, modified for covalent binding to degradable polyethylene glycol hydrogels, that prevents burst release and maintains abatacept and anti-CD40L at therapeutically effective local levels (e.g., low nanomolar concentrations representing ~10x IC50 values). In aim 2, the protocol for FRC co-transplantation will be optimized by determining the effects of IFNγ and antigen pre-conditioning on C57BL/6-derived FRC phenotype, in vitro efficacy of FRCs in attenuating alloresponses, and in vivo retention, viability, and in vivo efficacy of FRCs in attenuating alloresponse. Our approaches are applicable to islets as well as stem cell-derived beta cell replacements, novel extrahepatic confined transplantation sites, and other antibody-based drugs. Furthermore, our approaches could be exploited by other investigators to enhance current strategies to improve beta cell replacement therapies through islet transplantation, including those that have reached the clinical translation stage.
3-SRA-2024-1477-S-B Tomei (PI)
Type 1 diabetes (T1D) is an autoimmune disease that leads to selective destruction of insulin-secreting pancreatic β cells and lifelong dependence on exogenous insulin supplementation. In the US, 1.84 million people have T1D and 5 million people are expected to be diagnosed by 2050. Allogeneic β cell replacement through intrahepatic islet transplantation leads to better metabolic control, fewer long-term complications, and improved quality of life in patients with T1D as compared to exogenous insulin supplementation. The field of β cell replacement has recently benefited from major progress that addressed several limitations of the procedure for treatment of T1D. These recent advances have increased the hope of the millions of patients with T1D for a widely available cure. However, the continuing need for chronic systemic immunosuppression to prevent allorejection and recurrence of autoimmunity restricts the application of β cell replacement to the most severe cases of T1D due to a multitude of unavoidable side effects. Different strategies have been tested to achieve safer and more widely applicable β cell replacement for patients with T1D. Localized immunomodulation in the islet graft is enabled by extrahepatic transplantation in clinically-applicable confined sites such as the omental, intramuscular, and the subcutaneous sites. The clinically approved co-stimulation blocker abatacept (CTLA4Ig, human IgG1 subclass) blocks CD80/86 signaling required for T cell activation and promotes allograft survival in both preclinical models and in patients. Similarly, anti-CD40L antibodies were also effective in preclinical and clinical settings. However, systemic injection of these co-stimulatory blocking antibodies and immunomodulatory biologics in general is associated with adverse effects. This shortcoming can be addressed by non-systemic, localized, sustained delivery. Alternative to local immunosuppression, co-delivery of islets with immunomodulatory cells has demonstrated beneficial effects in islet transplantation by decreasing the need for systemic immunosuppression and inducing tolerance. Co-transplantation with tolerogenic non-professional stromal antigen-presenting fibroblastic reticular cells (FRCs) can also decrease alloreactive T cell activation and promote long-term allograft survival. These cells are a subpopulation of lymph node stromal cells that play key roles in peripheral tolerance through different mechanisms. We demonstrated that FRCs can present selected antigens to specific T cells inducing anergy and regulation in vitro. We hypothesize that localized and sustained release of selected human IgG1-based co-stimulatory blocking biologics by human IgG1-capturing degradable hydrogels co-delivered with islets in a confined site will prevent alloreactive T cell activation to prolong allograft survival in mice (aim 1). We also hypothesize that co-transplantation of pre-conditioned, antigen-primed, syngeneic fibroblastic reticular cells alongside allogeneic cells will decrease activation and tolerize recipient alloreactive T cells to improve murine allograft survival (aim 2). In aim 1, we will optimize the design of biologics-binding degradable hydrogels to provide sustained release of abatacept and anti-CD40L and test therapeutic efficacy in vitro and in vivo in murine allograft models. We will determine the dose of IgG1-binding peptide, modified for covalent binding to degradable polyethylene glycol hydrogels, that prevents burst release and maintains abatacept and anti-CD40L at therapeutically effective local levels (e.g., low nanomolar concentrations representing ~10x IC50 values). In aim 2, the protocol for FRC co-transplantation will be optimized by determining the effects of IFNγ and antigen pre-conditioning on C57BL/6-derived FRC phenotype, in vitro efficacy of FRCs in attenuating alloresponses, and in vivo retention, viability, and in vivo efficacy of FRCs in attenuating alloresponse. Our approaches are applicable to islets as well as stem cell-derived beta cell replacements, novel extrahepatic confined transplantation sites, and other antibody-based drugs. Furthermore, our approaches could be exploited by other investigators to enhance current strategies to improve beta cell replacement therapies through islet transplantation, including those that have reached the clinical translation stage.
Unraveling the tolerogenic potential of lymph node fibroblastic reticular networks in autoimmune diabetes
1 R01 DK141150 Tomei (PI), Creusot (C-PI)
Type 1 diabetes results from impaired central and peripheral tolerance mechanisms. b-cell antigen-reactive T cells escape negative selection in the thymus and regulation/deletion in the periphery. While the role and therapeutic potential of professional antigen-presenting cells and regulatory T cells in maintaining peripheral tolerance in type 1 diabetes is known, non-professional antigen presenting stromal cells residing in lymph nodes remain understudied. For maintaining and therapeutically promoting peripheral tolerance to self-antigens such as type 1 diabetes-relevant ones, these stromal cells present unique advantages over other antigen-presenting cells due to their lower costimulatory to coinhibitory molecules ratio, which remains stable during inflammation unlike activated professional antigen-presenting cells.
Our focus is on fibroblastic reticular cells (FRCs) which construct the lymph node stromal scaffold crucial for lymph node expansion during immune responses. FRC presentation of artificial antigens to specific T cells in lymph nodes lead to T cell deletion. Our studies showed that in the non-obese diabetic mouse model of type 1 diabetes, and in pancreatic lymph nodes from pancreatic organ donors with type 1 diabetes, the expression of the autoantigen insulin, the relative frequency of FRCs, and the FRC reticular remodeling properties are decreased. Thus, we hypothesize that peripheral expression and presentation of tissue-specific antigens by FRCs to autoreactive T cells may contribute to peripheral tolerance. To test our hypothesis that lymph node FRCs contribute to peripheral tolerance in type 1 diabetes, we have developed new mouse models to inhibit or enhance the capability of lymph node FRCs to express and present self and type 1 diabetes-relevant antigens. In Aim 1, we will evaluate the impact of these modifications on autoimmunity.
Additionally, to test FRCs’ ability to target autoreactive T cells and reduce autoimmunity, we propose innovative in vitroco-culture models with HLA-matched human cells in Aim 2. These studies are based on our preliminary data using murine FRCs. We demonstrated that (i) we can engineer FRC reticula that recapitulate FRC reticula organization and phenotype in lymph nodes, and (ii) genetically engineered FRC reticula to express and present type 1 diabetes-relevant antigens promote specific T cell anergy and regulatory T cells induction and expansion in vitro. Here, we will test the capability of human lymph node-derived FRCs to provide similar immunomodulatory effects on HLA-matched human T cells leading to decreased cytotoxicity on primary and stem cell-derived HLA-matched b-cells for translatability.
While the proposed studies are focused on the specific role and therapeutic application of lymph node FRCs in autoimmunity, our innovative immunoengineering approaches can be applied to the study of other lymphoid and mesenchymal stromal cells. The interdisciplinary nature of our MPI team positions us uniquely to conduct these studies.
1 R01 DK141150 Tomei (PI), Creusot (C-PI)
Type 1 diabetes results from impaired central and peripheral tolerance mechanisms. b-cell antigen-reactive T cells escape negative selection in the thymus and regulation/deletion in the periphery. While the role and therapeutic potential of professional antigen-presenting cells and regulatory T cells in maintaining peripheral tolerance in type 1 diabetes is known, non-professional antigen presenting stromal cells residing in lymph nodes remain understudied. For maintaining and therapeutically promoting peripheral tolerance to self-antigens such as type 1 diabetes-relevant ones, these stromal cells present unique advantages over other antigen-presenting cells due to their lower costimulatory to coinhibitory molecules ratio, which remains stable during inflammation unlike activated professional antigen-presenting cells.
Our focus is on fibroblastic reticular cells (FRCs) which construct the lymph node stromal scaffold crucial for lymph node expansion during immune responses. FRC presentation of artificial antigens to specific T cells in lymph nodes lead to T cell deletion. Our studies showed that in the non-obese diabetic mouse model of type 1 diabetes, and in pancreatic lymph nodes from pancreatic organ donors with type 1 diabetes, the expression of the autoantigen insulin, the relative frequency of FRCs, and the FRC reticular remodeling properties are decreased. Thus, we hypothesize that peripheral expression and presentation of tissue-specific antigens by FRCs to autoreactive T cells may contribute to peripheral tolerance. To test our hypothesis that lymph node FRCs contribute to peripheral tolerance in type 1 diabetes, we have developed new mouse models to inhibit or enhance the capability of lymph node FRCs to express and present self and type 1 diabetes-relevant antigens. In Aim 1, we will evaluate the impact of these modifications on autoimmunity.
Additionally, to test FRCs’ ability to target autoreactive T cells and reduce autoimmunity, we propose innovative in vitroco-culture models with HLA-matched human cells in Aim 2. These studies are based on our preliminary data using murine FRCs. We demonstrated that (i) we can engineer FRC reticula that recapitulate FRC reticula organization and phenotype in lymph nodes, and (ii) genetically engineered FRC reticula to express and present type 1 diabetes-relevant antigens promote specific T cell anergy and regulatory T cells induction and expansion in vitro. Here, we will test the capability of human lymph node-derived FRCs to provide similar immunomodulatory effects on HLA-matched human T cells leading to decreased cytotoxicity on primary and stem cell-derived HLA-matched b-cells for translatability.
While the proposed studies are focused on the specific role and therapeutic application of lymph node FRCs in autoimmunity, our innovative immunoengineering approaches can be applied to the study of other lymphoid and mesenchymal stromal cells. The interdisciplinary nature of our MPI team positions us uniquely to conduct these studies.
Funding Sources
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