Antibody blockade of Thy-1 (CD90) impairs mouse cytotoxic T lymphocyte induction by anti-CD3 monoclonal antibody

Naïve Primary Mouse CD8+ T Cells Retain In Vivo Immune Responsiveness After Electroporation-Based CRISPR/Cas9 Genetic Engineering

CRISPR/Cas9 technology has revolutionized genetic engineering of primary cells. Although its use is gaining momentum in studies on CD8⁺ T cell biology, it remains elusive to what extent CRISPR/Cas9 affects in vivo function of CD8⁺ T cells. Here, we optimized nucleofection-based CRISPR/Cas9 genetic engineering of naïve and in vitro-activated primary mouse CD8⁺ T cells and tested their in vivo immune responses. Nucleofection of naïve CD8⁺ T cells preserved their in vivo antiviral immune responsiveness to an extent that is indistinguishable from non-nucleofected cells, whereas nucleofection of in vitro-activated CD8⁺ T cells led to slightly impaired expansion/survival at early time point after adoptive transfer and more pronounced contraction. Of note, different target proteins displayed distinct decay rates after gene editing. This is in stark contrast to a comparable period of time required to complete gene inactivation. Thus, for optimal experimental design, it is crucial to determine the kinetics of the loss of target gene product to adapt incubation period after gene editing. In sum, nucleofection-based CRISPR/Cas9 genome editing achieves efficient and rapid generation of mutant CD8⁺ T cells without imposing detrimental constraints on their in vivo functions.

Cellular and Molecular Diversity in Scleroderma

With the increasing armamentarium of high-throughput tools available at manageable cost, it is attractive and informative to determine the molecular underpinnings of patient heterogeneity in systemic sclerosis (SSc). Given the highly variable clinical outcomes of patients labelled with the same diagnosis, unravelling the cellular and molecular basis of disease heterogeneity will be crucial to predicting disease risk, stratifying management and ultimately informing a patient-centered precision medicine approach. Herein, we summarise the findings of the past several years in the fields of genomics, transcriptomics, and proteomics that contribute to unraveling the cellular and molecular heterogeneity of SSc. Expansion of these findings and their routine integration with quantitative analysis of histopathology and imaging studies into clinical care promise to inform a scientifically driven patient-centred personalized medicine approach to SSc in the near future.

Neuronal CD200 Signaling Is Protective in the Acute Phase of Ischemic Stroke

BACKGROUND AND PURPOSE

CD200 (cluster of differentiation 200), a highly glycosylated protein primarily expressed on neurons in the central nervous system, binds with its receptor CD200R to form an endogenous inhibitory signal against immune responses. However, little is known about the effect of neuronal CD200 signaling in cerebral ischemia. The aim of this study was to investigate how neuronal CD200 signaling impacts poststroke inflammation and the ischemic injury.

METHODS

CD200 tma1^lf/fl:Thy1CreER mice were treated with tamoxifen to induce conditional gene knockout (ICKO) of neuronal CD200. The mice were subjected to a 60-minute transient middle cerebral artery occlusion. Stroke outcomes, apoptotic cell death, immune cell infiltration, microglia activation, and other inflammatory profiles were evaluated at 3 and 7 days after stroke.

RESULTS

Infarct volumes were significantly larger, and behavioral deficits more severe in ICKO versus control mice at 3 days after middle cerebral artery occlusion. Terminal deoxynucleotidyl transferase dUTP nick end labeling assay also revealed a significant increase in apoptotic neuronal death in CD200 ICKO mice. An enhancement in lymphocytic infiltration and microglial proinflammatory responses were revealed by flow cytometry at 3 and 7 days after stroke in ICKO mice, accompanied by an increased microglial phagocytosis activity. Plasma proinflammatory cytokine (TNFα [tumor necrosis factor alpha] and IL [interleukin]-1β) levels significantly increased at 3 days, and IL-1β/IL-6 levels increased at 7 days in ICKO versus control animals. ICKO led to significantly lower baseline level of CD200 both in brain and plasma.

CONCLUSIONS

Neuronal CD200 inhibits proinflammatory responses and is protective against stroke injury.

Thy-1 stimulation of mouse T cells induces a delayed T cell receptor-like signal that results in Ca2+‑independent cytotoxicity

Antibody-mediated crosslinking of Thy-1 [also known as cluster of differentiation (CD)90], results in a T cell receptor (TcR)‑like signal; however, the impact of Thy‑1 stimulation in comparison to TcR stimulation on T cell activation and effector function has yet to be fully elucidated. In the present study, the outcome of Thy‑1‑ and TcR‑induced stimulation of T cells was investigated in mice, using fragment crystalizable (Fc) receptor‑bound antibodies and costimulatory signals provided by syngeneic lipopolysaccharide‑matured bone marrow‑derived dendritic cells. Compared with TcR signaling, Thy‑1 signaling initiated a less robust proliferative response in T cells, as determined by tritiated‑thymidine incorporation. In addition, enzyme‑linked immunosorbent assays revealed that interleukin‑2 production was reduced, and the expression of CD25 and cyclin D3 was weaker in Thy‑1‑stimulated cells, as determined by western blotting; however, the expression of cyclin‑dependent kinase 6 was similar to that in TcR‑induced T cells. Furthermore, western blotting demonstrated that the phosphorylation of ζ-chain‑associated protein kinase 70 and extracellular signal‑regulated kinase 1/2 was delayed following Thy‑1 stimulation. DNA fragmentation assays revealed that cytotoxic effector function was also slower to develop in Thy‑1‑stimulated T cells, required more time to be effective and was largely Ca2+‑independent; these findings suggested that Fas ligand rather than granule‑associated perforin was involved in T cell effector function. In conclusion, the present results suggested that Thy‑1 signaling may contribute to the regulation of T cell homeostasis and the development of non‑specific T cell‑mediated cytotoxicity. However, further studies are required to elucidate the exact physiological roles of TcR‑like signals that result from Thy‑1 crosslinking and to investigate the molecular mechanisms that are involved.

Drug Delivery Using Nanoparticles for Cancer Stem-Like Cell Targeting

The theory of cancer stem-like cell (or cancer stem cell, CSC) has been established to explain how tumor heterogeneity arises and contributes to tumor progression in diverse cancer types. CSCs are believed to drive tumor growth and elicit resistance to conventional therapeutics. Therefore, CSCs are becoming novel target in both medical researches and clinical studies. Emerging evidences showed that nanoparticles effectively inhibit many types of CSCs by targeting various specific markers (aldehyde dehydrogenases, CD44, CD90, and CD133) and signaling pathways (Notch, Hedgehog, and TGF-β), which are critically involved in CSC function and maintenance. In this review, we briefly summarize the current status of CSC research and review a number of state-of-the-art nanomedicine approaches targeting CSC. In addition, we discuss emerging therapeutic strategies using epigenetic drugs to eliminate CSCs and inhibit cancer cell reprogramming.

Targeting cancer stem cells by using the nanoparticles

Cancer stem cells (CSCs) have been shown to be markedly resistant to conventional cancer treatments such as chemotherapy and radiation therapy. Therefore, therapeutic strategies that selectively target CSCs will ultimately lead to better cancer treatments. Currently, accessible conventional therapeutic agents mainly eliminate the bulk tumor but do not eliminate CSCs. Therefore, the discovery and improvement of CSC-targeting therapeutic agents are necessary. Nanoparticles effectively inhibit multiple types of CSCs by targeting specific signaling pathways (Wnt/β-catenin, Notch, transforming growth factor-β, and hedgehog signaling) and/or specific markers (aldehyde dehydrogenases, CD44, CD90, and CD133) critically involved in CSC function and maintenance. In this review article, we summarized a number of findings to provide current information about their therapeutic potential of nanoparticles in various cancer cell types and CSCs.

Tc17 Cells in Immunity and Systemic Autoimmunity

Tc17 cells-a subset of CD8(+)T cells-have recently been identified that are characterized by the production of interleukin (IL)-17. Cytokines IL-6 and transforming growth factor-beta 1 (TGF-β1) and transcription factors signaling transducers and activators of transcription (STAT)3, retinoic acid receptor-related orphan nuclear receptor gamma (RORγt), and interferon regulatory factor (IRF)4 are necessary for differentiation of Tc17 cells, controlling expression of molecules essential for Tc17 cell trafficking and function. Current human researches have determined the significance of CD161 expression as either a marker of Tc17 cells or as an effector and regulator of Tc17 cell function. Noncytotoxic Tc17 cells possess a high plasticity to convert into IFN-γ producing cells, which exhibit strong cytotoxic activity. The importance of in vivo plasticity of Tc17 cells for the induction of autoimmune diseases has been demonstrated and Tc17 cells potentially represent novel therapeutic targets in autoimmune diseases. The involvement of interleukin (IL)-17-producing CD8(+)T cells (Tc17) in various conditions, such as infection, cancer, and autoimmune inflammation, has been documented in both humans and mice; however, Tc17 cells have received only marginal attention. Here, we provide an overview of the cytokines and chemokines that characterize the murine and human Tc17 cells. Moreover, we discuss signaling pathways, molecular interactions, and transcriptional events that contribute to Tc17 differentiation and acquisition of effector functions. Also considered is the basis of Tc17 cell plasticity toward the Tc1 lineage, and we suggest that in vivo plasticity of Tc17 cells may be a key feature of Tc17 cell biology in autoimmune diseases. Furthermore, current human researches have revealed that Tc17 cells are different than that in mice because all of them express CD161 and exclusively originate from CD161 precursors present in umbilical cord blood. Finally, we focus on the recent evidence for long-lived Tc17 memory cell populations in mouse models and humans, and their functional roles in mediating disease memory. Hopefully, the information obtained will benefit for developing novel therapeutic strategies.

Impaired specific CD8 T cell response with aging is not due to decreased expression of CD90 on TCR transgenic T cells

BACKGROUND

CD90 (Thy-1) is a small glycoprotein that is particularly abundant on the surface of mouse thymocytes and peripheral T cells, and is often used as a marker in adoptive transfer experiments to distinguish donor and recipient T cells with different CD90 subtypes. We have performed adoptive transfer experiments with T cell receptor transgenic (TCR Tg) mice to study the impaired CD8 T cell response with aging.

FINDINGS

After stimulation with a CD8 T cell epitope, HA518-524, the response of TCR Tg CD8 T cells from aged mice was decreased compared to the response of TCR Tg T cells from young mice. CD90 expression was also substantially decreased on the TCR Tg CD8 T cells of aged mice. However, the responses of CD90hi and CD90low CD8 T cells of the aged mice were similar in both early activation and proliferation, demonstrating that the impaired Tg T cell response with aging is not associated with the altered CD90 expression on CD8 T cells.

CONCLUSIONS

The impaired Tg CD8 T cell response in aged mice is not due to age-associated changes in CD90 expression on Tg CD8 T cells.

Egr2 induced during DC development acts as an intrinsic negative regulator of DC immunogenicity

Early growth response gene 2 (Egr2), which encodes a zinc finger transcription factor, is rapidly and transiently induced in various cell types independently of de novo protein synthesis. Although a role for Egr2 is well established in T-cell development, Egr2 expression and its biological function in dendritic cells (DCs) have not yet been described. Here, we demonstrate Egr2 expression during DC development, and its role in DC-mediated immune responses. Egr2 is expressed in the later stage of DC development from BM precursor cells. Even at steady state, Egr2 is highly expressed in mouse splenic DCs. Egr2-knockdown (Egr2-KD) DCs showed increased levels of major histocompatability complex (MHC) class I and II and co-stimulatory molecules, and enhanced antigen uptake and migratory capacities. Furthermore, Egr2-KD abolished SOCS1 expression and signal transducer and activator of transcription 5 (STAT5) activation during DC development, probably resulting in the enhancement of IL-12 expression and Th1 immunogenicity of a DC vaccine. DC-mediated cytotoxic T lymphocyte (CTL) activation and antitumor immunity were significantly enhanced by Egr2-KD, and impaired by Egr2 overexpression in antigen-pulsed DC vaccines. These data suggest that Egr2 acts as an intrinsic negative regulator of DC immunogenicity and can be an attractive molecular target for DC vaccine development.

CISH is induced during DC development and regulates DC-mediated CTL activation

The cytokine inducible SH2-domain protein (CISH) is a well-known STAT5 target gene, but its role in the immune system remains uncertain. In this study, we found that CISH is predominantly induced during dendritic cell (DC) development from mouse bone marrow (BM) cells and plays a crucial role in type 1 DC development and DC-mediated CTL activation. CISH knockdown reduced the expression of MHC class I, co-stimulatory molecules and pro-inflammatory cytokines in BMDCs. Meanwhile, the DC yield was markedly enhanced by CISH knockdown via cell-cycle activation and reduction of cell apoptosis. Down-regulation of cell proliferation at the later stage of DC development was found to be associated with CISH-mediated negative feedback regulation of STAT5 activation. In T-cell immunity, OT-1 T-cell proliferation was significantly reduced by CISH knockdown in DCs, whereas OT-2 T-cell proliferation was not affected by CISH knockdown. CTLs generated by DC vaccination were also markedly reduced by CISH knockdown, followed by significant impairment of DC-based tumor immunotherapy. Taken together, our data suggest that CISH expression at the later stage of DC development triggers the shutdown of DC progenitor cell proliferation and facilitates DC differentiation into a potent stimulator of CTLs.

Engagement of glycosylphosphatidylinositol-anchored proteins results in enhanced mouse and human invariant natural killer T cell responses

Invariant natural killer T (iNKT) cells are a small subset of lymphocytes that recognize glycolipid antigens in the context of CD1d and consequently produce large quantities of pro-inflammatory and/or anti-inflammatory cytokines. Several transmembrane glycoproteins have been implicated in the co-stimulation of iNKT cell responses. However, whether glycosylphosphatidylinositol (GPI)-anchored proteins can function in this capacity is not known. Here, we demonstrate that antibody-mediated cross-linking of the prototype mouse GPI-anchored protein Thy-1 (CD90) on the surface of a double-negative (CD4⁻CD8⁻) iNKT cell line leads to cytokine production at both the mRNA and protein levels. In addition, Thy-1 triggering enhanced cytokine secretion by iNKT cells that were concomitantly stimulated with α-galactosylceramide (αGC), consistent with a co-stimulatory role for Thy-1 in iNKT cell activation. This was also evident when a CD4+ mouse iNKT cell line or primary hepatic NKT cells were stimulated with αGC and/or anti-Thy-1 antibody. Cross-linking Ly-6A/E, another GPI-anchored protein, could also boost cytokine secretion by αGC-stimulated iNKT cells, suggesting that the observed effects reflect a general property of GPI-anchored proteins. To extend these results from mouse to human cells, we focused on CD55, a GPI-anchored protein that, unlike Thy-1, is expressed on human iNKT cells. Cross-linking CD55 augmented αGC-induced iNKT cell responses as judged by more vigorous proliferation and higher CD69 expression. Collectively, these findings demonstrate for the first time that GPI-anchored proteins are able to co-stimulate CD1d-restricted, glycolipid-reactive iNKT cells in both mice and humans.

Thy-1 mRNA destabilization by norepinephrine a 3' UTR cAMP responsive decay element and involves RNA binding proteins

Thy-1 is a cell surface protein important in immunologic and neurologic processes, including T cell activation and proliferation, and neuronal outgrowth. In murine thymocytes, Thy-1 is downregulated in response to norepinephrine (NE) through posttranscriptional destabilization of its mRNA mediated by βAR/AC/cAMP/PKA signaling. In this study we investigated factors involved in NE/cAMP-mediated Thy-1 mRNA destabilization in S49 thymoma cells, and identified a region containing two copies of the AUUUA regulatory element (ARE), a motif commonly associated with mRNA decay, in the Thy-1 mRNA 3' UTR. Insertion of the Thy-1 ARE region into a reporter gene, resulted in cAMP induced destabilization of the reporter gene mRNA. RNA-protein binding studies revealed multiple Thy-1 ARE binding proteins, including AUF1, HuR, and TIAR. RNA silencing of HuR enhanced cAMP-mediated downregulation of Thy-1 mRNA, in contrast, silencing AUF1 had no effect. Immunoblotting revealed multiple proteins phosphorylated by PKA as a result of NE or cAMP signaling. These results reveal that the machinery of NE/cAMP modulation of Thy-1 mRNA decay involves a cAMP responsive ARE in its 3' UTR and multiple site specific ARE binding proteins. These findings add to our knowledge of Thy-1 mRNA regulation and provide insight into the regulation of ARE containing mRNAs, which impacts stress-related immunosuppression.

Thymus cell antigen 1 (Thy1, CD90) is expressed by lymphatic vessels and mediates cell adhesion to lymphatic endothelium

The lymphatic vascular system plays an important role in inflammation and cancer progression, although the molecular mechanisms involved are poorly understood. As determined by comparative transcriptional profiling studies of ex vivo isolated mouse intestinal lymphatic endothelial cells versus blood vascular endothelial cells, thymus cell antigen 1 (Thy1, CD90) was expressed at much higher levels in lymphatic endothelial cells than in blood vascular endothelial cells. These findings were confirmed by quantitative PCR, and at the protein level by FACS and immunofluorescence analyses. Thy1 was also strongly expressed by tumor-associated lymphatic vessels, as evaluated in a B16 melanoma footpad model in mice. Blockade of Thy1 inhibited tumor cell adhesion to cultured mouse lymphatic endothelial cells. Importantly, treatment of human dermal microvascular endothelial cells with tumor necrosis factor or phorbol 12-myristate 13-acetate resulted in Thy1 upregulation in podoplanin-expressing lymphatic endothelial cells, but not in podoplanin-negative blood vascular endothelial cells. Moreover, adhesion of human polymorphonuclear and mononuclear leukocytes to human lymphatic endothelial cells was Thy1-dependent. Together, these results identify Thy1 as a novel lymphatic vessel expressed gene and suggest its potential role in the cell adhesion processes required for tumor progression and inflammation.