directed-differentiation-induced-pluripotent-stem-cells-towards-t

Directed Differentiation of Induced Pluripotent Stem Cells towards T Lymphocytes

Adoptive cell transfer (ACT) of antigen-specific CD8+  cytotoxic T lymphocytes (CTLs) is a promising treatment for a variety of  malignancies 1. CTLs can  ...

stem-cell-derived-viral-ag-specific-t-lymphocytes-suppress-hbv

Stem Cell-Derived Viral Ag-Specific T Lymphocytes Suppress HBV Replication in Mice

Hepatitis B virus (HBV) infection is a global health issue. With over 350 million people affected worldwide, HBV infection remains the leading cause of ...

Pennsylvania State University College of Medicine

Harvard Medical School

Tumor necrosis factor (TNF)-α is upregulated in eyes following corneal alkali injury and contributes to corneal and also retinal damage. Prompt TNF-α inhibition by systemic infliximab ameliorates retinal damage and improves corneal wound healing. However, systemic administration of TNF-α inhibitors carries risk of significant complications, whereas topical eye-drop delivery is hindered by poor ocular bioavailability and the need for patient adherence. This study investigates the efficacy of subconjunctival delivery of TNF-α antibodies using a polymer-based drug delivery system (DDS).

Sustained Subconjunctival Delivery of Infliximab Protects the Cornea and Retina Following Alkali Burn to the Eye.

Alkali burns to the eye constitute a leading cause of worldwide blindness. In recent case series, corneal transplantation revealed unexpected damage to the retina and optic nerve in chemically burned eyes. We investigated the physical, biochemical, and immunological components of retinal injury after alkali burn and explored a novel neuroprotective regimen suitable for prompt administration in emergency departments. Thus, in vivo pH, oxygen, and oxidation reduction measurements were performed in the anterior and posterior segment of mouse and rabbit eyes using implantable microsensors. Tissue inflammation was assessed by immunohistochemistry and flow cytometry. The experiments confirmed that the retinal damage is not mediated by direct effect of the alkali, which is effectively buffered by the anterior segment. Rather, pH, oxygen, and oxidation reduction changes were restricted to the cornea and the anterior chamber, where they caused profound uveal inflammation and release of proinflammatory cytokines. The latter rapidly diffuse to the posterior segment, triggering retinal damage. Tumor necrosis factor-α was identified as a key proinflammatory mediator of retinal ganglion cell death. Blockade, by either monoclonal antibody or tumor necrosis factor receptor gene knockout, reduced inflammation and retinal ganglion cell loss. Intraocular pressure elevation was not observed in experimental alkali burns. These findings illuminate the mechanism by which alkali burns cause retinal damage and may have importance in designing therapies for retinal protection.

Mechanisms of Retinal Damage after Ocular Alkali Burns.

To propose a new treatment paradigm for chemical burns to the eye - in the acute and chronic phases.

Chemical Burns of the Eye: The Role of Retinal Injury and New Therapeutic Possibilities.

Eyes that have experienced alkali burn to the surface are excessively susceptible to subsequent severe glaucoma and retinal ganglion cell loss, despite maximal efforts to prevent or slow down the disease. Recently, we have shown, in mice and rabbits, that such retinal damage is neither mediated by the alkali itself reaching the retina nor by intraocular pressure elevation. Rather, it is caused by the up-regulation of tumor necrosis factor-α (TNF-α), which rapidly diffuses posteriorly, causing retinal ganglion cell apoptosis and CD45 cell activation. Herein, we investigated the involvement of peripheral blood monocytes and microglia in retinal damage. Using CX3CR1::CCR2 reporter mice and bone marrow chimeras, we show that peripheral CX3CR1CD45CD11bMHC-II monocytes infiltrate into the retina from the optic nerve at 24 hours after the burn and release further TNF-α. A secondary source of peripheral monocyte response originates from a rare population of patrolling myeloid CCR2 cells of the retina that differentiate into CX3CR1 macrophages within hours after the injury. As a result, CX3CR1CD45CD11b microglia become reactive at 7 days, causing further TNF-α release. Prompt TNF-α inhibition after corneal burn suppresses monocyte infiltration and microglia activation, and protects the retina. This study may prove relevant to other injuries of the central nervous system.

The Role of Microglia and Peripheral Monocytes in Retinal Damage after Corneal Chemical Injury.

Previous studies have demonstrated that ocular injury can lead to prompt infiltration of bone-marrow-derived peripheral monocytes into the retina. However, the ability of these cells to integrate into the tissue and become microglia has not been investigated. Here we show that such peripheral monocytes that infiltrate into the retina after ocular injury engraft permanently, migrate to the three distinct microglia strata, and adopt a microglia-like morphology. In the absence of ocular injury, peripheral monocytes that repopulate the retina after depletion with colony-stimulating factor 1 receptor (CSF1R) inhibitor remain sensitive to CSF1R inhibition and can be redepleted. Strikingly, consequent to ocular injury, the engrafted peripheral monocytes are resistant to depletion by CSF1R inhibitor and likely express low CSF1R. Moreover, these engrafted monocytes remain proinflammatory, expressing high levels of MHC-II, IL-1β, and TNF-α over the long term. The observed permanent neuroglia remodeling after injury constitutes a major immunological change that may contribute to progressive retinal degeneration. These findings may also be relevant to other degenerative conditions of the retina and the central nervous system.

Permanent neuroglial remodeling of the retina following infiltration of CSF1R inhibition-resistant peripheral monocytes.

Immunotherapy is a developing but very promising arsenal to treat cancer. Acquiring a more potent and effective approach in cancer immunotherapy is always the ultimate pursuance. CTL-based therapies are highly acclaimed recently due to its direct killing property. However, difficulty in obtaining adequate number of CTLs is still a major obstacle. In previous studies, it is shown that pluripotent stem cell-derived cytotoxic T lymphocytes (CTL)-especially the genetically engineered tumor antigen-specific CTLs-may serve as a good candidate for this goal. Here we introduce a novel approach in generating tumor antigen-specific CTLs from induced pluripotent stem cells (iPSCs) by using both in vitro and in vivo priming mechanisms for the tumor management in a murine melanoma model.

Generation of Tumor Antigen-Specific Cytotoxic T Lymphocytes from Pluripotent Stem Cells.

Reactive microglia and infiltrating peripheral monocytes have been implicated in many neurodegenerative diseases of the retina and CNS. However, their specific contribution in retinal degeneration remains unclear. We recently showed that peripheral monocytes that infiltrate the retina after ocular injury in mice become permanently engrafted into the tissue, establishing a proinflammatory phenotype that promotes neurodegeneration. In this study, we show that microglia regulate the process of neuroglia remodeling during ocular injury, and their depletion results in marked upregulation of inflammatory markers, such as , , and  in the retina, and abnormal engraftment of peripheral CCR2 CX3CR1 monocytes into the retina, which is associated with increased retinal ganglion cell loss, retinal nerve fiber layer thinning, and pigmentation onto the retinal surface. Furthermore, we show that other types of ocular injuries, such as penetrating corneal trauma and ocular hypertension also cause similar changes. However, optic nerve crush injury-mediated retinal ganglion cell loss evokes neither peripheral monocyte response in the retina nor pigmentation, although peripheral CX3CR1 and CCR2 monocytes infiltrate the optic nerve injury site and remain present for months. Our study suggests that microglia are key regulators of peripheral monocyte infiltration and retinal pigment epithelium migration, and their depletion results in abnormal neuroglia remodeling that exacerbates neuroretinal tissue damage. This mechanism of retinal damage through neuroglia remodeling may be clinically important for the treatment of patients with ocular injuries, including surgical traumas.

Microglia Regulate Neuroglia Remodeling in Various Ocular and Retinal Injuries.

The autoantigen-specific Tregs from pluripotent stem cells (PSCs), i.e., PSC-Tregs, have the ability to suppress autoimmunity. PSC-Tregs can be programmed to be tissue associated and to infiltrate into local inflamed tissues to suppress autoimmune responses after adoptive transfer. Nevertheless, the mechanisms by which the autoantigen-specific PSC-Tregs suppress the autoimmune response remain to be fully elucidated. In this study, we generated functional autoantigen-specific Tregs from the induced PSC (iPSCs), i.e., iPSC-Tregs, and investigated the underlying mechanisms of autoimmunity suppression by these Tregs in a type 1 diabetes (T1D) murine model. A double-Tg mouse model of T1D was established in F1 mice, in which the first generation of RIP-mOVA Tg mice that were crossed with OT-I T cell receptor (TCR) Tg mice was challenged with vaccinia viruses expressing OVA (VACV-OVA). We show that adoptive transfer of OVA-specific iPSC-Tregs greatly suppressed autoimmunity in the animal model and prevented the insulin-secreting pancreatic β cells from destruction. Further, we demonstrate that the adoptive transfer significantly reduced the expression of ICAM-1 in the diabetic pancreas and inhibited the migration of pathogenic CD8+ T cells and the production of the proinflammatory IFN-γ in the pancreas. These results indicate that the stem cell-derived tissue-associated Tregs can robustly accumulate in the diabetic pancreas, and, through downregulating the expression of ICAM-1 in the local inflamed tissues and inhibiting the production of proinflammatory cytokine IFN-γ, suppress the migration and activity of the pathogenic immune cells that cause T1D.

Stem cell-derived tissue-associated regulatory T cells suppress the activity of pathogenic cells in autoimmune diabetes.

In recent years cancer immunotherapy, especially the cell-based immunotherapy, has reached several milestones and achieved a lot of cancer remission in the clinics. Obtaining a more potent and effective cytotoxic T lymphocytes (CTLs) for cancer immunotherapy is always the ultimate goal for the researchers. However, the difficulty in harvesting a large number of tumor antigen-specific CTLs from the tumor patient is still a major obstacle we need to overcome. In our previous studies, it is shown that pluripotent stem cell-derived CTL-especially the genetically engineered antigen-specific CTLs-may serve as a good source of unlimited number of highly reactive and antigen-specific CTLs. Here we present a two-step method for the generation of antigen-specific T lymphocytes from iPS cells by in vitro priming and in vivo maturation.

In Vitro Differentiation of T Cells from Murine Pluripotent Stem Cells.

To review clinical aspects and cellular and molecular steps in the development of long-term glaucoma after corneal surgery or acute trauma-especially the pivotal role of tumor necrosis factor alpha (TNF-α), the rapidity of the secondary damage to the retinal ganglion cells, and the clinical promise of early antiinflammatory intervention.

Fengyang Lei

Department of Microbiology and Immunology

Pennsylvania State University College of Medicine

Directed Differentiation of Induced Pluripotent Stem Cells towards T Lymphocytes

Stem Cell-Derived Viral Ag-Specific T Lymphocytes Suppress HBV Replication in Mice

Fengyang Lei

.css-o250i3{font-size:18px;font-family:Open Sans,sans-serif;line-height:21.6px;}Department of Microbiology and Immunology

Pennsylvania State University College of Medicine

Directed Differentiation of Induced Pluripotent Stem Cells towards T Lymphocytes

Stem Cell-Derived Viral Ag-Specific T Lymphocytes Suppress HBV Replication in Mice

Department of Microbiology and Immunology