Advances in Engineering Myeloid Cells for Cell Therapy Applications.

Myeloid cells, including macrophages, neutrophils, dendritic cells, and myeloid-derived suppressor cells, play crucial roles in the innate immune system, contributing to immune defense, tissue homeostasis, and organ development. They have tremendous potential as therapeutic tools for diseases such as cancer and autoimmune disorders, but harnessing cell engineering strategies to enhance potency and expand applications is challenging. Recent advancements in stem cell research have made it possible to differentiate human embryonic stem cells and induce pluripotent stem cells into various cell types, including myeloid cells, offering a promising new approach to generate myeloid cells for cell therapy.

Harnessing the biology of regulatory T cells to treat disease.

Regulatory T (T) cells are a suppressive subset of CD4 T cells that maintain immune homeostasis and restrain inflammation. Three decades after their discovery, the promise of strategies to harness T cells for therapy has never been stronger. Multiple clinical trials seeking to enhance endogenous T cells or deliver them as a cell-based therapy have been performed and hint at signs of success, as well as to important limitations and unanswered questions.

CAR Treg synergy with anti-CD154 mediates infectious tolerance to dictate heart transplant outcomes.

Successful allograft specific tolerance induction would eliminate the need for daily immunosuppression and improve post-transplant quality of life. Adoptive cell therapy with regulatory T cells expressing donor-specific Chimeric Antigen Receptors (CAR-Tregs) is a promising strategy, but as monotherapy, cannot prolong the survival with allografts with multiple MHC mismatches. Using an HLA-A2-transgenic haplo-mismatched heart transplantation model in immunocompetent C57Bl/6 recipients, we show that HLA-A2-specific (A2) CAR Tregs was able to synergize with low dose of anti-CD154 to enhance graft survival.

Improving Reliability of Immunological Assays by Defining Minimal Criteria for Cell Fitness.

Human PBMC-based assays are often used as biomarkers for the diagnosis and prognosis of disease, as well as for the prediction and tracking of response to biological therapeutics. However, the development and use of PBMC-based biomarker assays is often limited by poor reproducibility. Complex immunological assays can be further complicated by variation in cell handling before analysis, especially when using cryopreserved cells.

Ustekinumab for type 1 diabetes in adolescents: a multicenter, double-blind, randomized phase 2 trial.

Immunotherapy targeting the autoimmune process in type 1 diabetes (T1D) can delay the loss of β-cells but needs to have minimal adverse effects to be an adjunct to insulin in the management of T1D. Ustekinumab binds to the shared p40 subunit of interleukin (IL)-12 and IL-23, targeting development of T helper 1 cells and T helper 17 cells (T1 and T17 cells) implicated in the pathogenesis of T1D. We conducted a double-blind, randomized controlled trial of ustekinumab in 72 adolescents aged 12-18 years with recent-onset T1D.

Immune phenotyping in a pediatric multicenter transplant study: Suitability of a preformulated dry-antibody panel system.

Flow-cytometric immune phenotyping is influenced by cryopreservation and inter-laboratory variability limiting comparability in multicenter studies. We assessed a system of optimized, pre-mixed dry-antibody panel tubes requiring small amounts of whole blood for validity, reliability and challenges in a Canadian multicenter study (POSITIVE) with long-distance sample shipping, using standardized protocols. Thirty-seven children awaiting solid-organ transplant were enrolled for parallel immune-phenotyping with both validated, optimized in-house panels and the dry-antibody system.

Short Report: CAR Tregs mediate linked suppression and infectious tolerance in islet transplantation.

Regulatory T cells (Tregs) have potential as a cell-based therapy to prevent or treat transplant rejection and autoimmunity. Using an HLA-A2-specific chimeric antigen receptor (A2-CAR), we previously showed that adoptive transfer of A2-CAR Tregs limited anti-HLA-A2 alloimmunity. However, it was unknown if A2-CAR Tregs could also limit immunity to autoantigens.

Genetic engineering of regulatory T cells for treatment of autoimmune disorders including type 1 diabetes.

Suppression of pathogenic immune responses is a major goal in the prevention and treatment of type 1 diabetes. Adoptive cell therapy using regulatory T cells (Tregs), a naturally suppressive immune subset that is often dysfunctional in type 1 diabetes, is a promising approach to achieving localised and specific immune suppression in the pancreas or site of islet transplant. However, clinical trials testing administration of polyclonal Tregs in recent-onset type 1 diabetes have observed limited efficacy despite an excellent safety profile.

SARS-CoV-2 Variants Omicron BA.4/5 and XBB.1.5 Significantly Escape T Cell Recognition in Solid-organ Transplant Recipients Vaccinated Against the Ancestral Strain.

Background: Immune-suppressed solid-organ transplant recipients (SOTRs) display impaired humoral responses to COVID-19 vaccination, but T cell responses are incompletely understood. SARS-CoV-2 variants Omicron BA.4/5 (BA.

First-in-human therapy with Treg produced from thymic tissue (thyTreg) in a heart transplant infant.

Due to their suppressive capacity, regulatory T cells (Tregs) have attracted growing interest as an adoptive cellular therapy for the prevention of allograft rejection, but limited Treg recovery and lower quality of adult-derived Tregs could represent an obstacle to success. To address this challenge, we developed a new approach that provides large quantities of Tregs with high purity and excellent features, sourced from thymic tissue routinely removed during pediatric cardiac surgeries (thyTregs). We report on a 2-year follow-up of the first patient treated worldwide with thyTregs, included in a phase I/II clinical trial evaluating the administration of autologous thyTreg in infants undergoing heart transplantation.

Tregs integrate native and CAR-mediated costimulatory signals for control of allograft rejection.

Tregs expressing chimeric antigen receptors (CAR-Tregs) are a promising tool to promote transplant tolerance. The relationship between CAR structure and Treg function was studied in xenogeneic, immunodeficient mice, revealing advantages of CD28-encoding CARs. However, these models could underrepresent interactions between CAR-Tregs, antigen-presenting cells (APCs), and donor-specific Abs.

Tregs with an MHC class II peptide-specific chimeric antigen receptor prevent autoimmune diabetes in mice.

Adoptive immunotherapy with Tregs is a promising approach for preventing or treating type 1 diabetes. Islet antigen-specific Tregs have more potent therapeutic effects than polyclonal cells, but their low frequency is a barrier for clinical application. To generate Tregs that recognize islet antigens, we engineered a chimeric antigen receptor (CAR) derived from a monoclonal antibody with specificity for the insulin B chain 10-23 peptide presented in the context of the IAg7 MHC class II allele present in NOD mice.

Human A2-CAR T Cells Reject HLA-A2 + Human Islets Transplanted Into Mice Without Inducing Graft-versus-host Disease.

Background: Type 1 diabetes is an autoimmune disease characterized by T-cell-mediated destruction of pancreatic beta-cells. Islet transplantation is an effective therapy, but its success is limited by islet quality and availability along with the need for immunosuppression. New approaches include the use of stem cell-derived insulin-producing cells and immunomodulatory therapies, but a limitation is the paucity of reproducible animal models in which interactions between human immune cells and insulin-producing cells can be studied without the complication of xenogeneic graft-versus-host disease (xGVHD).

Eras of designer Tregs: Harnessing synthetic biology for immune suppression.

Since their discovery, CD4 CD25 FOXP3 regulatory T cells (Tregs) have been firmly established as a critical cell type for regulating immune homeostasis through a plethora of mechanisms. Due to their immunoregulatory power, delivery of polyclonal Tregs has been explored as a therapy to dampen inflammation in the settings of transplantation and autoimmunity. Evidence shows that Treg therapy is safe and well-tolerated, but efficacy remains undefined and could be limited by poor persistence in vivo and lack of antigen specificity.

Regulatory T Cell Biomarkers Identify Patients at Risk of Developing Acute Cellular Rejection in the First Year Following Heart Transplantation.

Background: Acute cellular rejection (ACR), an alloimmune response involving CD4+ and CD8+ T cells, occurs in up to 20% of patients within the first year following heart transplantation. The balance between a conventional versus regulatory CD4+ T cell alloimmune response is believed to contribute to developing ACR. Therefore, tracking these cells may elucidate whether changes in these cell populations could signal ACR risk.

Acidity promotes the differentiation of immunosuppressive regulatory T cells.

The metabolic milieu is emerging as a major contributing factor in the maintenance of the immunosuppressive microenvironment within tumors. In particular, the presence of lactic acid produced by highly glycolytic cancer cells is known to suppress antitumor immune cell subsets while promoting immunosuppressive cell populations, such as regulatory T cells (Tregs). Unlike conventional T cells, Tregs have a unique, potent ability to take up lactic acid to fuel both mitochondrial metabolism and gluconeogenesis, thus supporting suppressive function and proliferation.

Sex biased human thymic architecture guides T cell development through spatially defined niches.

Within the thymus, regulation of the cellular cross-talk directing T cell development is dependent on spatial interactions within specialized niches. To create a holistic, spatially defined map of tissue niches guiding postnatal T cell development we employed the multidimensional imaging platform CO-detection by indEXing (CODEX), as well as CITE-seq and ATAC-seq. We generated age-matched 4-5-month-old postnatal thymus datasets for male and female donors, and identify significant sex differences in both T cell and thymus biology.

Tonic-signaling chimeric antigen receptors drive human regulatory T cell exhaustion.

Regulatory T cell (Treg) therapy is a promising approach to improve outcomes in transplantation and autoimmunity. In conventional T cell therapy, chronic stimulation can result in poor in vivo function, a phenomenon termed exhaustion. Whether or not Tregs are also susceptible to exhaustion, and if so, if this would limit their therapeutic effect, was unknown.