Nikole Perdue

The transcription factor T-bet controls regulatory T cell homeostasis and function during type 1 inflammation

Several subsets of Foxp3+ regulatory T cells (Treg cells) work in concert to maintain immune homeostasis. However, the molecular bases underlying the phenotypic and functional diversity of Treg cells remain obscure. We show that in response to interferon-γ, Foxp3+ Treg cells upregulated the T helper type 1 (TH1)-specifying transcription factor T-bet. T-bet promoted expression of the chemokine receptor CXCR3 on Treg cells, and T-bet+ Treg cells accumulated at sites of TH1 cell–mediated inflammation. Furthermore, T-bet expression was required for the homeostasis and function of Treg cells during type 1 inflammation. Thus, in a subset of CD4+ T cells, the activities of the transcription factors Foxp3 and T-bet are overlaid, which results in Treg cells with unique homeostatic and migratory properties optimized for the suppression of TH1 responses in vivo.

Altering the distribution of Foxp3+ regulatory T cells results in tissue-specific inflammatory disease

CD4+Foxp3+ regulatory T cells (T reg) are essential for maintaining self-tolerance, but their functional mechanisms and sites of action in vivo are poorly defined. We examined the homing receptor expression and tissue distribution of T reg cells in the steady state and determined whether altering their distribution by removal of a single chemokine receptor impairs their ability to maintain tissue-specific peripheral tolerance. We found that T reg cells are distributed throughout all nonlymphoid tissues tested, and are particularly prevalent in the skin, where they express a unique CCR4+CD103hi phenotype. T reg cell expression of CCR4 and CD103 is induced by antigen-driven activation within subcutaneous lymph nodes, and accumulation of T reg cells in the skin and lung airways is impaired in the absence of CCR4 expression. Mice with a complete loss of CCR4 in the T reg cell compartment develop lymphocytic infiltration and severe inflammatory disease in the skin and lungs, accompanied by peripheral lymphadenopathy and increased differentiation of skin-tropic CD4+Foxp3+ T cells. Thus, selectively altering T reg cell distribution in vivo leads to the development of tissue-specific inflammatory disease.

Foxp3+ regulatory T cells maintain immune homeostasis in the skin

Cutaneous immune responses must be tightly controlled to prevent unwanted inflammation in response to innocuous antigens, while maintaining the ability to combat skin-tropic pathogens. Foxp3+ regulatory T (T reg) cells are potent immune regulators and are found at high frequency in both human and mouse skin. Although T reg cells migrate to the skin and can dampen immune responses during experimentally induced inflammation or infection, the importance of cutaneous T reg cells for maintaining normal immune homeostasis in the skin has not been addressed. To selectively block T reg cell function in the skin, we restored the T reg cell compartment in Foxp3-deficient scurfy mice with cells whose ability to migrate to the skin was impaired because of targeted mutation of α-1,3-fucosyltransferase VII (Fut7). Although Fut7-deficient T reg cells were present at normal frequency and could function in all other tissues examined, these animals rapidly developed severe cutaneous inflammation. Thus, skin-resident T reg cell are essential for maintaining normal immune homeostasis at this site.

Matricellular protein SPARC is translocated to the nuclei of immortalized murine lens epithelial cells.

The matricellular glycoprotein, secreted protein acidic and rich in cysteine (SPARC), has complex biological activities and is important for lens epithelial cell function and regulation of cataract formation. To understand how SPARC influences lens epithelial cell activity and homeostasis, we have studied the subcellular distribution of SPARC in murine lens epithelial cells in vitro. We demonstrate that endogenous SPARC is located in the cytoplasm of either quiescent or dividing lens epithelial cells in culture. However, cytoplasmic SPARC was translocated into the nuclei of immortalized lens epithelial cells upon a significant reduction of intracellular SPARC in these cells. Recombinant human (rh) SPARC added to the culture media was quickly and efficiently internalized into the cytosol of SPARC‐null lens epithelial cells. Moreover, cytoplasmic rhSPARC was also translocated into the nucleus after exogenous rhSPARC was removed from the culture media. The translocation of SPARC into the nucleus was therefore triggered by the reduction of SPARC protein normally available to the cells. A mouse SPARC–EGFP chimeric fusion protein (70 kDa) was expressed in lens epithelial cells and 293‐EBNA cells, and was observed both in the cytoplasm and culture medium, but not in the nucleus. SPARC does not appear to have a strong nuclear localization sequence. Alternatively, SPARC might pass through the nuclear pore complex by passive diffusion. SPARC therefore functions not only as an extracellular protein but also potentially as an intracellular protein to influence cellular activities and homeostasis.

A Self-Reactive TCR Drives the Development of Foxp3+ Regulatory T Cells That Prevent Autoimmune Disease

Although Foxp3+ regulatory T cells (Tregs) are thought to express autoreactive TCRs, it is not clear how individual TCRs influence Treg development, phenotype, and function in vivo. We have generated TCR transgenic mice (termed SFZ70 mice) using Tcra and Tcrb genes cloned from an autoreactive CD4+ T cell isolated from a Treg-deficient scurfy mouse. The SFZ70 TCR recognizes a cutaneous autoantigen and drives development of both conventional CD4+ Foxp3− T cells (Tconv) and Foxp3+ Tregs. SFZ70 Tregs display an activated phenotype evidenced by robust proliferation and expression of skin-homing molecules such as CD103 and P-selectin ligand. Analysis of Foxp3-deficient SFZ70 mice demonstrates that Tregs inhibit Tconv cell expression of tissue-homing receptors and their production of proinflammatory cytokines. In addition, Treg suppression of SFZ70 Tconv cells can be overcome by nonspecific activation of APCs. These results provide new insights into the differentiation and function of tissue-specific Tregs in vivo and provide a tractable system for analyzing the molecular requirements of Treg-mediated tolerance toward a cutaneous autoantigen.

Differential responses of human lens epithelial cells to intraocular lenses in vitro: hydrophobic acrylic versus PMMA or silicone discs

BackgroundThe purpose of this study was to determine the influence of different materials of intraocular lenses (IOLs) on human lens epithelial cell behavior, including adhesion, migration, proliferation, apoptosis, and epithelial-mesenchymal transdifferentiation (EMT) in vitro.MethodsHuman lens epithelial cells (SRA 01/04) were grown on hydrophobic acrylic (Acrysof), polymethylmethacrylate (PMMA), and silicone IOLs. Cellular adhesion, migration, proliferation, and apoptotic assays were performed to assess cell behavior. The expression of EMT markers (fibronectin and type I collagen) produced by cells on IOLs was determined by immunoblotting and immunocytochemistry.ResultsHuman lens epithelial cells exhibited preferred adhesion and reduced apoptosis when cultured on acrylic IOLs, in comparison to PMMA and silicone IOLs. Cells grown on acrylic lenses formed a confluent epithelial monolayer. Migration of lens epithelial cells under the acrylic lens was substantially blocked in an in vitro assay. In contrast, cells grown on PMMA and silicone lenses displayed a spindle-shaped, myofibroblast-like morphology, increased apoptosis, reduced adhesion, and enhanced production of EMT proteins such as fibronectin and type I collagen. The migration of lens epithelial cells under PMMA and silicone IOLs was substantial in the in vitro assay.ConclusionThis report demonstrates that hydrophobic acrylic lenses are more capsular biocompatible than PMMA and silicone lenses. The in vitro assays are reliable measurements for evaluating the responses of human lens epithelial cells to different IOL materials, and could advance our understanding of the preferential capsular opacification conferred by different IOL materials.

Type-1 immunity drives early lethality in scurfy mice.

Foxp3+ regulatory T (Treg) cells modulate the functions of multiple immune cell types, and loss of Treg cells causes lethal, CD4+ T‐cell‐dependent multiorgan autoimmune disease in both mice and humans. However, how different effector T‐cell subets contribute to the severe autoimmunity observed in the absence of Treg cells remains controversial. We found that although expanded populations of Th1, Th2, and Th17 cells can be detected in scurfy (sf) mice, Th1 cells predominate. Moreover, using a genetic approach, we found that sf mice with deficiencies in type‐1 immunity (sf × Ifngr1−/−, sf × Tbx21−/−, and sf × Ifngr1−/−/Tbx21−/−) have an extended lifespan that is associated with altered cytokine production and attenuated cutaneous and hepatic inflammation. By contrast, sf mice deficient in type‐2 immune responses (sf × Stat6−/−) display a significantly reduced lifespan with increased hepatic inflammation, but decreased dermatitis. These data indicate that Th1 cells and their associated cytokines drive early immunopathology in Foxp3‐deficient sf mice, highlighting the essential role of Treg cells in restraining Th1‐cell‐mediated autoimmunity.

Cellular Requirements for Diabetes Induction in DO11.10xRIPmOVA Mice

Type 1 diabetes (T1D) results from the immune-mediated destruction of the insulin-producing β-islet cells in the pancreas. The genetic and environmental mechanisms promoting the development of this disease remain poorly understood. We have explored the cellular requirements for T1D development in DO11.10xRIPmOVA (DORmO) mice, which carry a TCR transgene specific for an MHC class II-restricted epitope from OVA and express membrane-bound OVA in the pancreas under the control of the rat insulin promoter. We found that DORmO.RAG2−/− mice do not develop insulitis and are completely protected from diabetes, demonstrating that endogenous lymphocyte receptor rearrangement is required for disease development. Diabetes in DORmO mice is preceded by the development of OVA-specific autoantibodies and is delayed in B cell-deficient DORmO.JhD−/− mice, demonstrating that B cells contribute to disease progression. In addition, transfer of CD8+ T cells from diabetic animals into DORmO.RAG2−/− mice promoted insulitis by OVA-specific CD4+ T cells. Finally, although diabetes develops in DORmO mice in the presence of a significant population of Foxp3+ OVA-specific regulatory T cells, boosting regulatory T cell numbers by injecting IL-2 immune complexes dampens autoantibody production and prevents development of insulitis and overt diabetes. These results help define the events leading to diabetes in DORmO mice and provide new insights into the cellular interactions required for disease development in an Ag-specific model of T1D.

Evaluation of immune activation following neoadjuvant sipuleucel-T in subjects with localized prostate cancer.

178 Background: Sipuleucel-T is an FDA-approved autologous cellular therapy that has been demonstrated to prolong overall survival in subjects with asymptomatic or minimally symptomatic metastatic castrate resistant prostate cancer (mCRPC). METHODS Subjects with localized prostate cancer were enrolled in an open-label, Phase 2 study (P07-1; NCT00715104 ) in which they received 3 infusions of sipuleucel-T at approximately 2-week intervals, beginning 6-7 weeks prior to radical prostatectomy. All samples were evaluated for cellular composition and antigen presenting cell (APC) activation pre- and post-culture with PA2024, a fusion protein comprising prostatic acid phosphatase and granulocyte macrophage-colony stimulating factor. Additionally, cytokines within the culture supernatant were assessed, and T and B cell activation were evaluated pre- and post-culture using flow cytometry. RESULTS Of the 42 enrolled subjects (median age: 61 years; 98% Caucasian), 38 received all 3 infusions of sipuleucel-T. Consistent with previous trials in mCRPC, CD54 upregulation (APC activation) was greater at the second and third infusions relative to the first. While the percent of CD4+ and CD8+ T cells was unchanged with treatment, the expression of early T cell activation markers (CD134, CD137, CD278 and CD279) was increased in pre-culture cells obtained after the first infusion, and further increased post-culture. Similarly, while the percent of B cells was unchanged, there was a progressive increase in memory B cells (CD20+CD27+IgD-CD86+; pre- and post-culture) and activated mature B cells (CD20+CD27+IgD+CD86+; post-culture) following the first infusion. Activated T cell-associated cytokines were significantly elevated (TNF-α, P < 0.001; IFN-γ, P < 0.001; and IL-2, P < 0.001) in the second and third products. CONCLUSIONS Neoadjuvant sipuleucel-T resulted in robust immune system activation that included APCs, memory and activated mature B cells, and both CD4+ and CD8+ T cells. The patterns observed at the second and third infusions, relative to the first, are consistent with an immunological prime-boost profile.