Keunhee Oh

Epithelial transglutaminase 2 is needed for T cell interleukin-17 production and subsequent pulmonary inflammation and fibrosis in bleomycin-treated mice

Inhibition of transglutaminase 2 reduces bleomycin-induced epithelial cell release of interleukin 6 in vitro and pulmonary inflammation and fibrosis in vivo.

A mutual activation loop between breast cancer cells and myeloid-derived suppressor cells facilitates spontaneous metastasis through IL-6 trans-signaling in a murine model

IntroductionTumor cell interactions with the microenvironment, especially those of bone-marrow-derived myeloid cells, are important in various aspects of tumor metastasis. Myeloid-derived suppressor cells (MDSCs) have been suggested to constitute tumor-favoring microenvironments. In this study, we elucidated a novel mechanism by which the MDSCs can mediate spontaneous distant metastasis of breast cancer cells.MethodsMurine breast cancer cells, 4T1 and EMT6, were orthotopically grafted into the mammary fat pads of syngeneic BALB/c mice. CD11b+Gr-1+ MDSCs in the spleen, liver, lung and primary tumor mass were analyzed. To evaluate the role of MDSCs in the distant metastasis, MDSCs were depleted or reconstituted in tumor-bearing mice. To evaluate whether MDSCs in the metastasizing tumor microenvironment affect breast cancer cell behavior, MDSCs and cancer cells were co-cultivated. To investigate the role of MDSCs in in vivo metastasis, we blocked the interactions between MDSCs and cancer cells.ResultsUsing a murine breast cancer cell model, we showed that murine breast cancer cells with high IL-6 expression recruited more MDSCs and that the metastasizing capacity of cancer cells paralleled MDSC recruitment in tumor-bearing mice. Metastasizing, but not non-metastasizing, tumor-derived factors induced MDSCs to increase IL-6 production and full activation of recruited MDSCs occurred in the primary tumor site and metastatic organ in the vicinity of metastasizing cancer cells, but not in lymphoid organs. In addition, tumor-expanded MDSCs expressed Adam-family proteases, which facilitated shedding of IL-6 receptor, thereby contributing to breast cancer cell invasiveness and distant metastasis through IL-6 trans-signaling. The critical role of IL-6 trans-signaling was confirmed in both the afferent and efferent pathways of metastasis.ConclusionIn this study, we showed that metastasizing cancer cells induced higher MDSCs infiltration and prompted them to secret exaggerated IL-6 as well as soluble IL-6Rα, which, in turn, triggered a persistent increase of pSTAT3 in tumor cells. This potential tumor-MDSC axis involving IL-6 trans-signaling directly affected breast cancer cell aggressiveness, leading to spontaneous metastasis.

Activation of AMP-activated Protein Kinase Is Essential for Lysophosphatidic Acid-induced Cell Migration in Ovarian Cancer Cells

Lysophosphatidic acid (LPA) is a bioactive phospholipid that affects various biological functions, such as cell proliferation, migration, and survival, through LPA receptors. Among them, the motility of cancer cells is an especially important activity for invasion and metastasis. Recently, AMP-activated protein kinase (AMPK), an energy-sensing kinase, was shown to regulate cell migration. However, the specific role of AMPK in cancer cell migration is unknown. The present study investigated whether LPA could induce AMPK activation and whether this process was associated with cell migration in ovarian cancer cells. We found that LPA led to a striking increase in AMPK phosphorylation in pathways involving the phospholipase C-β3 (PLC-β3) and calcium/calmodulin-dependent protein kinase kinase β (CaMKKβ) in SKOV3 ovarian cancer cells. siRNA-mediated knockdown of AMPKα1, PLC-β3, or (CaMKKβ) impaired the stimulatory effects of LPA on cell migration. Furthermore, we found that knockdown of AMPKα1 abrogated LPA-induced activation of the small GTPase RhoA and ezrin/radixin/moesin proteins regulating membrane dynamics as membrane-cytoskeleton linkers. In ovarian cancer xenograft models, knockdown of AMPK significantly decreased peritoneal dissemination and lung metastasis. Taken together, our results suggest that activation of AMPK by LPA induces cell migration through the signaling pathway to cytoskeletal dynamics and increases tumor metastasis in ovarian cancer.

Direct Regulatory Role of NKT Cells in Allogeneic Graft Survival Is Dependent on the Quantitative Strength of Antigenicity

The role of NKT cells during immune responses is diverse, ranging from antiviral and antitumor activity to the regulation of autoimmune diseases; however, the regulatory function of CD1d-dependent NKT cells in rejection responses against allogeneic graft is uncertain. In this study, we demonstrated the direct regulatory effects of CD1d-dependent NKT cells using an allogeneic skin transplantation model. H-Y-mismatched skin graft survival was shortened in CD1d−/− recipients compared with wild-type recipients. Adoptive transfer of syngeneic NKT cells via splenocytes or hepatic mononuclear cells into CD1d−/− recipients restored graft survival times to those of wild-type recipients. α-Galactosylceramide, a specific activator of NKT cells, further prolonged graft survival. Although CD1d-dependent NKT cells did not extend skin graft survival in either major or complete minor histocompatibility-mismatched models, these cells affected graft survival in minor Ag mismatch models according to the magnitude of the antigenic difference. The afferent arm of NKT cell activation during transplantation required CD1d molecules expressed on host APCs and the migration of CD1d-dependent NKT cells into grafts. Moreover, the regulatory effects of CD1d-dependent NKT cells against alloantigen were primarily IL-10 dependent. Taken together, we concluded that CD1d-dependent NKT cells may directly affect the outcome of allogeneic skin graft through an IL-10-dependent regulatory mechanism.

Cp-690550, a Janus Kinase Inhibitor, Suppresses Cd4+ T-cell–mediated Acute Graft-versus-host Disease by Inhibiting the Interferon-γ Pathway

Background. Acute graft-versus-host disease (GVHD) is a critical obstacle to bone marrow transplantation. Although numerous studies have described immunosuppression protocols to mitigate acute GVHD, the need still exists for a more efficient immunosuppressant with fewer side effects. Here, we evaluated the protective effect of CP-690550, a newly developed Janus kinase inhibitor, in an acute GVHD model. Methods. CP-690550 was chemically synthesized. Acute GVHD was induced through the transfer of parent B6 (H-2b) bone marrow and CD4+ T cells into lethally irradiated (B6×bm12)F1 (H-2b×bm12) mice. Results. CP-690550 treatments confined to days −3 to 11 of GVHD induction provided full protection against allogeneic, acute GVHD-related lethality and histopathology. An analysis of the initial donor-derived CD4+ T-cell responses revealed that the inhibitory effects of CP-690550 were largely related to the suppression of donor CD4+ T-cell–mediated interferon (IFN)-&ggr; production. Enhanced inhibition of T helper 1 cell differentiation, rather than the inhibition of allogeneic CD4+ T-cell proliferation or T helper 17 cell differentiation, was also confirmed in allogeneic mixed lymphocyte reactions. Because lethality was considerably delayed by the systemic blockade of IFN-&ggr;, the principal protective effect of CP-690550 occurred through the modulation of IFN-&ggr; production. Conclusion. The targeting of Janus kinase with a sensitive and specific inhibitor, CP-690550, conferred effective protection from acute GVHD induced by a semiallogeneic major histocompatibility complex class II-disparate combination. Protection from acute GVHD was largely mediated by the inhibition of IFN-&ggr; production.

Transglutaminase 2 facilitates the distant hematogenous metastasis of breast cancer by modulating interleukin-6 in cancer cells

IntroductionInflammation has been implicated in cancer aggressiveness. As transglutaminase 2 (TG2), which has been associated with inflammatory signaling, has been suggested to play a role in tumor behavior, we propose that TG2 may be an important linker inducing interleukin (IL)-6-mediated cancer-cell aggressiveness, including distant hematogenous metastasis.MethodsTo investigate the role for TG2 and IL-6, TG2-knocked-down and IL-6-knocked-down cancer cells were generated by using shRNA. Human breast cancer cell xenograft model in highly immunocompromised mice and human advanced breast cancer primary tumor tissue microarrays were used in this study.ResultsIL-6 production in human breast cancer cells was dependent on their TG2 expression level. In vitro tumor-sphere formation was dependent on TG2 and downstream IL-6 production from cancer cells. Primary tumor growth in the mammary fat pads and distant hematogenous metastasis into the lung was also dependent on TG2 and downstream IL-6 expression levels. The effect of TG2 expression on human breast cancer distant metastasis was investigated by analyzing a tissue microarray of primary tumors from 412 patients with their clinical data after 7 years. TG2 expression in primary tumor tissue was inversely correlated with recurrence-free survival (P = 0.019) and distant metastasis-free survival (DMFS) (P = 0.006) in patients with advanced breast cancer. Furthermore, by using public datasets that included a total of 684 breast cancer patients, we found that the combined high expression of TG2 and IL-6 was associated with shorter DMFS, compared with the high expression of IL-6 only (P = 0.013).ConclusionsWe provide evidence that TG2 is an important link in IL-6-mediated tumor aggressiveness, and that TG2 could be an important mediator of distant metastasis, both in a xenograft animal model and in patients with advanced breast cancer.

Invariant NKT cells regulate experimental autoimmune uveitis through inhibition of Th17 differentiation

Although NKT cells have been implicated in diverse immunomodulatory responses, the effector mechanisms underlying the NKT cell‐mediated regulation of pathogenic T helper cells are not well understood. Here, we show that invariant NKT cells inhibited the differentiation of CD4+ T cells into Th17 cells both in vitro and in vivo. The number of IL‐17‐producing CD4+ T cells was reduced following co‐culture with purified NK1.1+TCR+ cells from WT, but not from CD1d−/− or Jα18−/−, mice. Co‐cultured NKT cells from either cytokine‐deficient (IL‐4−/−, IL‐10−/−, or IFN‐γ−/−) or WT mice efficiently inhibited Th17 differentiation. The contact‐dependent mechanisms of NKT cell‐mediated regulation of Th17 differentiation were confirmed using transwell co‐culture experiments. On the contrary, the suppression of Th1 differentiation was dependent on IL‐4 derived from the NKT cells. The in vivo regulatory capacity of NKT cells on Th17 cells was confirmed using an experimental autoimmune uveitis model induced with human IRBP1–20 (IRBP, interphotoreceptor retinoid‐binding protein) peptide. NKT cell‐deficient mice (CD1d−/− or Jα18−/−) demonstrated an increased disease severity, which was reversed by the transfer of WT or cytokine‐deficient (IL‐4−/−, IL‐10−/−, or IFN‐γ−/−) NKT cells. Our results indicate that invariant NKT cells inhibited autoimmune uveitis predominantly through the cytokine‐independent inhibition of Th17 differentiation.

Porcine PD-L1: cloning, characterization, and implications during xenotransplantation

Abstract: Background:  Effective intervention achieved by manipulating cell‐mediated xenogeneic immune responses would critically increase the clinical feasibility of xenotransplantation as immediate hyperacute rejections become controllable through genetic modulations of donor organs. Endogenous negative regulatory signals like the programmed death 1 (PD‐1)‐programmed death ligand 1 (PD‐L1) system are candidate targets for the control of cell‐mediated xenogeneic immune response.

Transglutaminase 2 exacerbates experimental autoimmune encephalomyelitis through positive regulation of encephalitogenic T cell differentiation and inflammation

The increased activity of transglutaminase 2 (TG2) in various inflammatory and fibrotic conditions results in the development of numerous disease processes. Experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis, is an inflammatory and demyelinating disease of the central nervous system and is mediated by many inflammatory cytokines and mediators. We examined the role of TG2 in encephalitogenic CD4(+) T cell responses and EAE development using mice lacking TG2 (TG2(-/-)). TG2(-/-) mice showed decreased disease severity as compared with wild-type (WT) mice. Treatment with cysteamine, a TG2 inhibitor, ameliorated disease severity in WT mice. Exacerbated disability in WT mice resulted from the increased infiltration of cytokine-producing CD4(+) T cells and sustained expression of inflammatory cytokines and mediators in the lesion. The increased number of IL-17- and IFN-γ-producing cells in the spinal cord resulted from peripheral expansion of these cells after immunization with myelin-derived antigen. In vitro differentiation of WT and TG2(-/-) splenocytes revealed that proliferation and activation-induced cell death did not differ, but differentiation into IL-17- or IFN-γ-producing cells was increased in WT mice. Adoptive transfer experiments revealed that pathogenic CD4(+) T cell differentiation and disease progression were caused by both the T cell-intrinsic and -extrinsic effects of TG2. This study is the first to report a pathogenic role for TG2 in the EAE progress and suggests that therapeutic targeting of TG2 may be effective against multiple sclerosis.

Structural phase transitions of Ge2Sb2Te5 cells with TiN electrodes using a homemade W heater tip

The phase transitions of a Ge2Sb2Te5 cell with a volume of 20×20×0.1μm3 were carried out by applying a reset pulse (10V and 50ns) and a subsequent set pulse (5V and 300ns) using a homemade W heater tip fabricated by focused ion beam lithography. The phase transformation from a crystalline state to an amorphous state was confirmed by measuring the I-V curves and observation with a cross-sectional transmission electron microscope both before and after applying the reset pulse. The electron diffraction pattern obtained from the transformed area clearly showed the amorphous state. The resistance value of the transformed amorphous area was two orders higher than that of the original crystalline phase. This difference in the resistance value between the reset and set states was maintained for 20 reset/set pulse cycles. It is expected that this experimental setup can be used to evaluate the fatigue behavior of Ge2Sb2Te5 cells with reset/set pulse cycles.