The Experts below are selected from a list of 5061 Experts worldwide ranked by ideXlab platform

Seok Jin Kim - One of the best experts on this subject based on the ideXlab platform.

Yasuyuki Goto - One of the best experts on this subject based on the ideXlab platform.

  • Hemophagocytosis induced by Leishmania donovani infection is beneficial to parasite survival within macrophages.
    PLoS neglected tropical diseases, 2019
    Co-Authors: Ayako Morimoto, Kazuyuki Uchida, James K. Chambers, Kai Sato, Jing Hong, Chizu Sanjoba, Yoshitsugu Matsumoto, Junya Yamagishi, Yasuyuki Goto
    Abstract:

    Visceral leishmaniasis (VL) is caused by parasitic protozoa of the genus Leishmania and is characterized by clinical manifestations such as fever, hepatosplenomegaly and anemia. Hemophagocytosis, the phenomenon of phagocytosis of blood cells by macrophages, is found in VL patients. In a previous study we established an experimental model of VL, reproducing anemia in mice for the first time, and identified Hemophagocytosis by heavily infected macrophages in the spleen as a possible cause of anemia. However, the mechanism for parasite-induced Hemophagocytosis or its role in parasite survival remained unclear. Here, we established an in vitro model of Leishmania-induced Hemophagocytosis to explore the molecules involved in this process. In contrast to naive RAW264.7 cells (mouse macrophage cell line) which did not uptake freshly isolated erythrocytes, RAW264.7 cells infected with L. donovani showed enhanced phagocytosis of erythrocytes. Additionally, for hemophagocytes found both in vitro and in vivo, the expression of signal regulatory protein α (SIRPα), one of the receptors responsible for the 'don't-eat-me' signal was suppressed by post-transcriptional control. Furthermore, the overlapped phagocytosis of erythrocytes and Leishmania parasites within a given macrophage appeared to be beneficial to the parasites; the in vitro experiments showed a higher number of parasites within macrophages that had been induced to engulf erythrocytes. Together, these results suggest that Leishmania parasites may actively induce Hemophagocytosis by manipulating the expression of SIRPα in macrophages/hemophagocytes, in order to secure their parasitism.

  • Prevalence, severity, and pathogeneses of anemia in visceral leishmaniasis
    Parasitology Research, 2017
    Co-Authors: Yasuyuki Goto, Satoko Omachi, Jingjie Cheng, Ayako Morimoto
    Abstract:

    Anemia is a typical symptom during visceral leishmaniasis (VL). We performed a systematic analysis of the literature on anemia in VL to understand the prevalence, severity, and possible mechanisms. Anemia is very common in VL patients with an overall prevalence higher than 90 %. The degree of anemia in VL is moderate to severe (hemoglobin level ∼7.5 g/dl), and the status can be recovered by treatment with antileishmanial drugs within a certain period of time. Possible pathogeneses of anemia in VL based on clinical observations included anti-RBC antibodies, dysfunction in erythropoiesis, and Hemophagocytosis in the bone marrow or spleen, while hemolysis is a more likely cause than dyserythropoiesis. In hamsters with experimental VL, Hemophagocytosis induced by immune complex and changes on erythrocyte membrane is speculated as the pathogenesis for anemia. In contrast, our recent study on murine VL indicated that Hemophagocytosis contributes to anemia in contrast to lower contribution of anti-RBC antibodies or dysfunction in erythropoiesis. Together, Hemophagocytosis is most likely associated with anemia in VL, and elucidation of the immunological mechanisms may lead to development of novel interventions to manage the symptom.

  • Hemophagocytosis in Experimental Visceral Leishmaniasis by Leishmania donovani.
    PLoS neglected tropical diseases, 2016
    Co-Authors: Ayako Morimoto, Kazuyuki Uchida, James K. Chambers, Chizu Sanjoba, Yoshitsugu Matsumoto, Satoko Omachi, Yasutaka Osada, Yasuyuki Goto
    Abstract:

    Hemophagocytosis is a phenomenon in which macrophages phagocytose blood cells. There are reports on up-regulated Hemophagocytosis in patients with infectious diseases including typhoid fever, tuberculosis, influenza and visceral leishmaniasis (VL). However, mechanisms of infection-associated Hemophagocytosis remained elusive due to a lack of appropriate animal models. Here, we have established a mouse model of VL with Hemophagocytosis. At 24 weeks after infection with 1 x 10(7) Leishmania donovani promastigotes, BALB/cA mice exhibited splenomegaly with an average tissue weight per body weight of 2.96%. In the tissues, 28.6% of macrophages contained phagocytosed erythrocytes. All of the hemophagocytosing macrophages were parasitized by L. donovani, and higher levels of Hemophagocytosis was observed in heavily infected cells. Furthermore, more than half of these hemophagocytes had two or more macrophage-derived nuclei, whereas only 15.0% of splenic macrophages were bi- or multi-nuclear. These results suggest that direct infection by L. donovani causes hyper-activation of host macrophages to engulf blood cells. To our knowledge, this is the first report on Hemophagocytosis in experimental Leishmania infections and may be useful for further understanding of the pathogenesis.

Shinjiro Todo - One of the best experts on this subject based on the ideXlab platform.

Shotai Kobayashi - One of the best experts on this subject based on the ideXlab platform.

  • Hemophagocytosis associated with MPO-ANCA positive vasculitis in systemic sclerosis.
    Clinical and experimental rheumatology, 2002
    Co-Authors: Kumakura S, H Ishikura, Murakawa Y, Masahiro Kondo, Shotai Kobayashi
    Abstract:

    Hemophagocytosis is a histiocytic proliferative condition associated with underlying disorders such as infection, lymphoma and autoimmune disease. We describe here a patient with systemic sclerosis who developed MPO-ANCA positive necrotizing vasculitis and Hemophagocytosis concomitantly. Vasculitis supervened on a prior systemic sclerosis, and no causative disorder of Hemophagocytosis could be found other than active vasculitis, suggesting that an occurrence of Hemophagocytosis is associated with underlying vasculitis. Immunosuppressive therapy resulted in excellent improvement of both the Hemophagocytosis and vasculitis. On the other hand, this case shows the elevated serum levels of IL-1beta, IL-6 and M-CSF which may be involved in the pathogenesis of Hemophagocytosis. To our knowledge, this is the first demonstration indicating the possibility of vasculitis-associated Hemophagocytosis.

  • Reactive Hemophagocytosis in Systemic Lupus Erythematosus
    Internal medicine (Tokyo Japan), 1998
    Co-Authors: Kazuo Takahashi, Shunichi Kumakura, Hiroto Ishikura, Yohko Murakawa, Yasutaka Yamauchi, Shotai Kobayashi
    Abstract:

    A patient with systemic lupus erythematosus (SLE) developed reactive Hemophagocytosis. This case did not show any underlying diseases such as infection or malignancy other than SLE itself. The mechanisms inducing Hemophagocytosis in SLE seem to be heterogeneous and remain to be elucidated. Although an immune complex-mediated mechanism in cases with acute lupus hemophagocytic syndrome has been proposed, we suggest the possible involvement of IL-1β as the pathogenesis of our case.(Internal Medicine 37: 550-553, 1998)

  • Adult onset Still's disease associated Hemophagocytosis.
    The Journal of rheumatology, 1997
    Co-Authors: Kumakura S, H Ishikura, S Munemasa, T Adachi, Murakawa Y, Shotai Kobayashi
    Abstract:

    Reactive Hemophagocytosis is characterized by the activation of histiocytes with prominent Hemophagocytosis in the reticuloendothelial system, and usually occurs in association with underlying disorders such as viral or bacterial infection and malignancy. We describe 3 cases of adult onset Still's disease (AOSD) who developed Hemophagocytosis in bone marrow. Extensive studies could not identify any viral infection or other known underlying disorders for reactive Hemophagocytosis except for active AOSD. Although the causative mechanisms of reactive Hemophagocytosis in AOSD are not clear, our cases suggest the possibility of AOSD associated Hemophagocytosis.

Ayako Morimoto - One of the best experts on this subject based on the ideXlab platform.

  • Hemophagocytosis induced by Leishmania donovani infection is beneficial to parasite survival within macrophages.
    PLoS neglected tropical diseases, 2019
    Co-Authors: Ayako Morimoto, Kazuyuki Uchida, James K. Chambers, Kai Sato, Jing Hong, Chizu Sanjoba, Yoshitsugu Matsumoto, Junya Yamagishi, Yasuyuki Goto
    Abstract:

    Visceral leishmaniasis (VL) is caused by parasitic protozoa of the genus Leishmania and is characterized by clinical manifestations such as fever, hepatosplenomegaly and anemia. Hemophagocytosis, the phenomenon of phagocytosis of blood cells by macrophages, is found in VL patients. In a previous study we established an experimental model of VL, reproducing anemia in mice for the first time, and identified Hemophagocytosis by heavily infected macrophages in the spleen as a possible cause of anemia. However, the mechanism for parasite-induced Hemophagocytosis or its role in parasite survival remained unclear. Here, we established an in vitro model of Leishmania-induced Hemophagocytosis to explore the molecules involved in this process. In contrast to naive RAW264.7 cells (mouse macrophage cell line) which did not uptake freshly isolated erythrocytes, RAW264.7 cells infected with L. donovani showed enhanced phagocytosis of erythrocytes. Additionally, for hemophagocytes found both in vitro and in vivo, the expression of signal regulatory protein α (SIRPα), one of the receptors responsible for the 'don't-eat-me' signal was suppressed by post-transcriptional control. Furthermore, the overlapped phagocytosis of erythrocytes and Leishmania parasites within a given macrophage appeared to be beneficial to the parasites; the in vitro experiments showed a higher number of parasites within macrophages that had been induced to engulf erythrocytes. Together, these results suggest that Leishmania parasites may actively induce Hemophagocytosis by manipulating the expression of SIRPα in macrophages/hemophagocytes, in order to secure their parasitism.

  • Prevalence, severity, and pathogeneses of anemia in visceral leishmaniasis
    Parasitology Research, 2017
    Co-Authors: Yasuyuki Goto, Satoko Omachi, Jingjie Cheng, Ayako Morimoto
    Abstract:

    Anemia is a typical symptom during visceral leishmaniasis (VL). We performed a systematic analysis of the literature on anemia in VL to understand the prevalence, severity, and possible mechanisms. Anemia is very common in VL patients with an overall prevalence higher than 90 %. The degree of anemia in VL is moderate to severe (hemoglobin level ∼7.5 g/dl), and the status can be recovered by treatment with antileishmanial drugs within a certain period of time. Possible pathogeneses of anemia in VL based on clinical observations included anti-RBC antibodies, dysfunction in erythropoiesis, and Hemophagocytosis in the bone marrow or spleen, while hemolysis is a more likely cause than dyserythropoiesis. In hamsters with experimental VL, Hemophagocytosis induced by immune complex and changes on erythrocyte membrane is speculated as the pathogenesis for anemia. In contrast, our recent study on murine VL indicated that Hemophagocytosis contributes to anemia in contrast to lower contribution of anti-RBC antibodies or dysfunction in erythropoiesis. Together, Hemophagocytosis is most likely associated with anemia in VL, and elucidation of the immunological mechanisms may lead to development of novel interventions to manage the symptom.

  • Hemophagocytosis in Experimental Visceral Leishmaniasis by Leishmania donovani.
    PLoS neglected tropical diseases, 2016
    Co-Authors: Ayako Morimoto, Kazuyuki Uchida, James K. Chambers, Chizu Sanjoba, Yoshitsugu Matsumoto, Satoko Omachi, Yasutaka Osada, Yasuyuki Goto
    Abstract:

    Hemophagocytosis is a phenomenon in which macrophages phagocytose blood cells. There are reports on up-regulated Hemophagocytosis in patients with infectious diseases including typhoid fever, tuberculosis, influenza and visceral leishmaniasis (VL). However, mechanisms of infection-associated Hemophagocytosis remained elusive due to a lack of appropriate animal models. Here, we have established a mouse model of VL with Hemophagocytosis. At 24 weeks after infection with 1 x 10(7) Leishmania donovani promastigotes, BALB/cA mice exhibited splenomegaly with an average tissue weight per body weight of 2.96%. In the tissues, 28.6% of macrophages contained phagocytosed erythrocytes. All of the hemophagocytosing macrophages were parasitized by L. donovani, and higher levels of Hemophagocytosis was observed in heavily infected cells. Furthermore, more than half of these hemophagocytes had two or more macrophage-derived nuclei, whereas only 15.0% of splenic macrophages were bi- or multi-nuclear. These results suggest that direct infection by L. donovani causes hyper-activation of host macrophages to engulf blood cells. To our knowledge, this is the first report on Hemophagocytosis in experimental Leishmania infections and may be useful for further understanding of the pathogenesis.