generation-of-human-chimeric-antigen-receptor-regulatory-t-cells

Generation of Human Chimeric Antigen Receptor Regulatory T Cells

Chimeric antigen receptor (CAR) T-cell therapy has reshaped the face of cancer treatment, leading to record remission rates in previously incurable ...

Medical University of South Carolina

CAR T-Cell Therapy: Is CD28-CAR Heterodimerization Its Achilles' Heel?

Type 1 diabetes (T1D) is an autoimmune disease characterized by impaired immune tolerance to β-cell antigens and progressive destruction of insulin-producing β-cells. Animal models have provided valuable insights for understanding the etiology and pathogenesis of this disease, but they fall short of reflecting the extensive heterogeneity of the disease in humans, which is contributed by various combinations of risk gene alleles and unique environmental factors. Collectively, these factors have been used to define subgroups of patients, termed endotypes, with distinct predominating disease characteristics.

Modeling human T1D-associated autoimmune processes.

TNFa blocking agents were the first-in-class biologic drugs used for the treatment of autoimmune disease. Paradoxically, however, exacerbation of autoimmunity was observed in some patients. TNFa is a pleiotropic cytokine that has both proinflammatory and regulatory effects on CD4 T cells and can influence the adaptive immune response against autoantigens. Here, we critically appraise the literature and discuss the intricacies of TNFa signaling that may explain the controversial findings of previous studies. The pleiotropism of TNFa is based in part on the existence of two biologically active forms of TNFa, soluble and membrane-bound, with different affinities for two distinct TNF receptors, TNFR1 and TNFR2, leading to activation of diverse downstream molecular pathways involved in cell fate decisions and immune function. Distinct membrane expression patterns of TNF receptors by CD4 T cell subsets and their preferential binding of distinct forms of TNFα produced by a diverse pool of cellular sources during different stages of an immune response are important determinants of the differential outcomes of TNFa-TNF receptor signaling. Targeted manipulation of TNFa-TNF receptor signaling on select CD4 T cell subsets may offer specific therapeutic interventions to dampen inflammation while fortifying immune regulation for the treatment of autoimmune diseases.

The dichotomous outcomes of TNFα signaling in CD4 T cells.

Novel biologics are currently being tested in clinical trials for the treatment of autoimmune diseases and the prevention of transplant allograft rejection. Their premise is to deliver highly efficient immunosuppression while minimizing side-effects, as they specifically target inflammatory mediators involved in the dysregulation of the immune system. However, the pleiotropism of soluble mediators and cell-to-cell interactions with potential to exert both proinflammatory and regulatory influences on the outcome of the immune response can lead to unpredictable results. Predicting responses to biologic drugs requires mechanistic understanding of the cell type-specific effect of immune mediators. Elucidation of the central role of regulatory T cells (Treg), a small subset of T cells dedicated to immune homeostasis, in preventing the development of auto- and allo-immunity has provided a deeper understanding of the signaling pathways that govern immune tolerance. This review focuses on the requisite signals that promote Treg homeostasis and discusses the anticipated outcomes of biologics targeting these signals. Our goal is to inform and facilitate the design of cell-specific biologics that thwart T effector cells (Teff) while promoting Treg function for the treatment of autoimmune diseases and the prevention of transplant rejection.

Regulatory T cell homeostasis: Requisite signals and implications for clinical development of biologics.

Autoimmune disease, caused by unwanted immune responses to self-antigens, affects millions of people each year and poses a great social and economic burden to individuals and communities. In the course of autoimmune disorders, including rheumatoid arthritis, systemic lupus erythematosus, type 1 diabetes mellitus, and multiple sclerosis, disturbances in the balance between the immune response against harmful agents and tolerance towards self-antigens lead to an immune response against self-tissues. In recent years, various regulatory immune cells have been identified. Disruptions in the quality, quantity, and function of these cells have been implicated in autoimmune disease development. Therefore, targeting or engineering these cells is a promising therapeutic for different autoimmune diseases. Regulatory T cells, regulatory B cells, regulatory dendritic cells, myeloid suppressor cells, and some subsets of innate lymphoid cells are arising as important players among this class of cells. Here, we review the roles of each suppressive cell type in the immune system during homeostasis and in the development of autoimmunity. Moreover, we discuss the current and future therapeutic potential of each one of these cell types for autoimmune diseases.

The emerging role of regulatory cell-based therapy in autoimmune disease.

Lymphodepleting pre-conditioning is a nearly universal component of T cell adoptive transfer protocols. The side effects of pre-conditioning regimens used in adoptive cell therapy are clinically significant and include pan-cytopenia, immune suppression, and reactive myelopoiesis. We conducted studies to test the hypothesis that the mechanisms underlying effective engraftment are cell autonomous and not dependent on a lymphodepleted host immune status. These studies leveraged mouse models to examine the role of Stat5 signaling during T cell adoptive transfer. We observed that, by transiently expressing a constitutively active mutamer of Stat5b during the process of adoptive transfer, we could completely obviate the need for lymphodepletion prior to adoptive transfer. Using several functional assays, we benchmark the function of the engrafted T cells against T cells transferred after conventional lymphodepletion. These studies identify a cell-autonomous mechanism driven by transient Stat5b signaling with lasting effects on T cell phenotype and function. Furthermore, the results presented suggest that adoptive T cell therapy could be improved by removing lymphodepletion protocols entirely and replacing them with RNA transfection of T cells with transcripts encoding active Stat5.

Efficient T cell adoptive transfer in lymphoreplete hosts mediated by transient activation of Stat5 signaling.

The adaptive immune system exhibits exquisite specificity and memory and is involved in virtually every process in the human body. Redirecting adaptive immune cells, in particular T cells, to desired targets has the potential to lead to the creation of powerful cell-based therapies for a wide range of maladies. While conventional effector T cells (Teff) would be targeted towards cells to be eliminated, such as cancer cells, immunosuppressive regulatory T cells (Treg) would be directed towards tissues to be protected, such as transplanted organs. Chimeric antigen receptors (CARs) are designer molecules comprising an extracellular recognition domain and an intracellular signaling domain that drives full T cell activation directly downstream of target binding. Here, we describe procedures to generate and evaluate human CAR CD4 helper T cells, CD8 cytotoxic T cells, and CD4FOXP3 regulatory T cells.

Redirecting Human Conventional and Regulatory T Cells Using Chimeric Antigen Receptors.

Chimeric antigen receptor (CAR) T cell therapy has proven to be a successful treatment option for leukemias and lymphomas. These encouraging outcomes underscore the potential of adoptive cell therapy for other oncology applications, namely, solid tumors. However, CAR T cells are yet to succeed in treating solid tumors. Unlike liquid tumors, solid tumors create a hostile tumor microenvironment (TME). CAR T cells must traffic to the TME, survive, and retain their function to eradicate the tumor. Nevertheless, there is no universal preclinical model to systematically test candidate CARs and CAR targets for their capacity to infiltrate and eliminate human solid tumors in vivo. Here, we provide a detailed protocol to evaluate human CAR CD4 helper T cells and CD8 cytotoxic T cells in immunodeficient (NSG) mice bearing antigen-expressing human solid tumors.

How to Test Human CAR T Cells in Solid Tumors, the Next Frontier of CAR T Cell Therapy.

Implantation and maintenance of pregnancy involve intricate immunological processes that enable the developing fetus to coexist with the maternal immune system. Progesterone, a critical hormone during pregnancy, is known to promote immune tolerance and prevent preterm labor. However, the mechanism by which progesterone mediates these effects remains unclear. In this study, we investigated the role of the non-classical progesterone receptor membrane component 1 (PGRMC1) in progesterone signaling at the maternal-fetal interface. Using JEG3 cells, a trophoblast model cell line, we observed that progesterone stimulation increased the expression of human leukocyte antigen-C (HLA-C) and HLA-G, key molecules involved in immune tolerance. We also found that progesterone upregulated the expression of the transcription factor ELF3, which is known to regulate trophoblast-specific HLA-C expression. Interestingly, JEG3 cells lacked expression of classical progesterone receptors (PRs) but exhibited high expression of PGRMC1, a finding we confirmed in primary trophoblasts by mining sc-RNA seq data from human placenta. To investigate the role of PGRMC1 in progesterone signaling, we used CRISPR/Cas9 technology to knockout PGRMC1 in JEG3 cells. PGRMC1-deficient cells showed a diminished response to progesterone stimulation. Furthermore, we found that the progesterone antagonist RU486 inhibited ELF3 expression in a PGRMC1-dependent manner, suggesting that RU486 acts as a progesterone antagonist by competing for receptor binding. Additionally, we found that RU486 inhibited cell invasion, an important process for successful pregnancy, and this inhibitory effect was dependent on PGRMC1. Our findings highlight the crucial role of PGRMC1 in mediating the immunoregulatory effects of progesterone at the maternal-fetal interface.

Progesterone-mediated remodeling of the maternal-fetal interface by a PGRMC1-dependent mechanism.

Regulatory T cells (Tregs) are promising cellular therapies to induce immune tolerance in organ transplantation and autoimmune disease. The success of chimeric antigen receptor (CAR) T-cell therapy for cancer has sparked interest in using CARs to generate antigen-specific Tregs. Here, we compared CAR with endogenous T cell receptor (TCR)/CD28 activation in human Tregs. Strikingly, CAR Tregs displayed increased cytotoxicity and diminished suppression of antigen-presenting cells and effector T (Teff) cells compared with TCR/CD28 activated Tregs. RNA sequencing revealed that CAR Tregs activate Teff cell gene programs. Indeed, CAR Tregs secreted high levels of inflammatory cytokines, with a subset of FOXP3 CAR Tregs uniquely acquiring CD40L surface expression and producing IFNγ. Interestingly, decreasing CAR antigen affinity reduced Teff cell gene expression and inflammatory cytokine production by CAR Tregs. Our findings showcase the impact of engineered receptor activation on Treg biology and support tailoring CAR constructs to Tregs for maximal therapeutic efficacy.

High affinity chimeric antigen receptor signaling induces an inflammatory program in human regulatory T cells.

Adoptive chimeric antigen receptor T-cell (CAR-T) therapy is transformative and approved for hematologic malignancies. It is also being developed for the treatment of solid tumors, autoimmune disorders, heart disease, and aging. Despite unprecedented clinical outcomes, CAR-T and other engineered cell therapies face a variety of manufacturing and safety challenges. Traditional methods, such as lentivirus transduction and electroporation, result in random integration or cause significant cellular damage, which can limit the safety and efficacy of engineered cell therapies. We present hydroporation as a gentle and effective alternative for intracellular delivery. Hydroporation resulted in 1.7- to 2-fold higher CAR-T yields compared to electroporation with superior cell viability and recovery. Hydroporated cells exhibited rapid proliferation, robust target cell lysis, and increased pro-inflammatory and regulatory cytokine secretion in addition to improved CAR-T yield by day 5 post-transfection. We demonstrate that scaled-up hydroporation can process 5 x 10 cells in less than 10 s, showcasing the platform as a viable solution for high-yield CAR-T manufacturing with the potential for improved therapeutic outcomes.

Scalable intracellular delivery via microfluidic vortex shedding enhances the function of chimeric antigen receptor T-cells.

Adoptive chimeric antigen receptor T-cell (CAR-T) therapy is transformative and approved for hematologic malignancies. It is also being developed for the treatment of solid tumors, autoimmune disorders, heart disease, and aging. Despite unprecedented clinical outcomes, CAR-T and other engineered cell therapies face a variety of manufacturing and safety challenges. Traditional methods, such as lentivirus transduction and electroporation, result in random integration or cause significant cellular damage, which can limit the safety and efficacy of engineered cell therapies. We present hydroporation as a gentle and effective alternative for intracellular delivery. Hydroporation resulted in 1.7- to 2-fold higher CAR-T yields compared to electroporation with superior cell viability and recovery. Hydroporated cells exhibited rapid proliferation, robust target cell lysis, and increased pro-inflammatory and regulatory cytokine secretion in addition to improved CAR-T yield by day 5 post-transfection. We demonstrate that scaled-up hydroporation can process 5 × 10 cells in less than 10 s, showcasing the platform as a viable solution for high-yield CAR-T manufacturing with the potential for improved therapeutic outcomes.

Regenerative medicine is a rapidly expanding field harnessing human pluripotent stem cell (hPSC)-derived cells and tissues to treat many diseases, including type 1 diabetes. However, graft immune protection remains a key challenge. Chimeric antigen receptor (CAR) technology confers new specificities to effector T cells and immunosuppressive regulatory T cells (Tregs). One challenge in CAR design is identifying target molecules unique to the cells of interest. Here, we employ combinatorial genetic engineering to confer CAR-Treg-mediated localized immune protection to stem cell-derived cells. We engineered hPSCs to express truncated epidermal growth factor receptor (EGFRt), a biologically inert and generalizable target for CAR-Treg homing and activation, and generated CAR-Tregs recognizing EGFRt. Strikingly, CAR-Tregs suppressed innate and adaptive immune responses in vitro and prevented EGFRt-hPSC-derived pancreatic beta-like cell (sBC [stem cell-derived beta cell]) graft immune destruction in vivo. Collectively, we provide proof of concept that hPSCs and Tregs can be co-engineered to protect hPSC-derived cells from immune rejection upon transplantation.

Combinatorial genetic engineering strategy for immune protection of stem cell-derived beta cells by chimeric antigen receptor regulatory T cells.

Regulatory T cells (Tregs) are promising cellular therapies to induce immune tolerance in organ transplantation and autoimmune disease. The success of chimeric antigen receptor (CAR) T cell therapy for cancer has sparked interest in using CARs to generate antigen-specific Tregs. Here, we compared CAR with endogenous T cell receptor (TCR)/CD28 activation in human Tregs. Strikingly, CAR Tregs displayed increased cytotoxicity and diminished suppression of antigen-presenting cells and effector T (Teff) cells compared with TCR/CD28-activated Tregs. RNA sequencing revealed that CAR Tregs activate Teff cell gene programs. Indeed, CAR Tregs secreted high levels of inflammatory cytokines, with a subset of FOXP3 CAR Tregs uniquely acquiring CD40L surface expression and producing IFN-γ. Interestingly, decreasing CAR antigen affinity reduced Teff cell gene expression and inflammatory cytokine production by CAR Tregs. Our findings showcase the impact of engineered receptor activation on Treg biology and support tailoring CAR constructs to Tregs for maximal therapeutic efficacy.

Leonardo M. R. Ferreira

Department of Microbiology and Immunology,
Department of Regenerative Medicine and Cell Biology,
Hollings Cancer Center

Medical University of South Carolina

Generation of Human Chimeric Antigen Receptor Regulatory T Cells

Leonardo M. R. Ferreira

.css-o250i3{font-size:18px;font-family:Open Sans,sans-serif;line-height:21.6px;}Department of Microbiology and Immunology,Department of Regenerative Medicine and Cell Biology,Hollings Cancer Center

Medical University of South Carolina

Generation of Human Chimeric Antigen Receptor Regulatory T Cells

Department of Microbiology and Immunology,
Department of Regenerative Medicine and Cell Biology,
Hollings Cancer Center