Vitreoretinal lymphoma (VRL) is a subtype of diffuse large B-cell lymphoma and is sight- and life-threatening in the vast majority of patients. Lymphoma cells infiltrate the vitreous body and/or ...subretinal space and exhibit clinical signs of vitreous opacities and creamy white subretinal lesions. Although the intraocular signs can serve as clues to suspect VRL, they are nonspecific and may be misdiagnosed as uveitis. Histopathological evidence of malignant cells on vitreous biopsy, for instance, is the gold standard for diagnosis of VRL; however, cytological examination of the vitreous often results in a low success rate owing to the small quantity and poor quality of tissues and cells in the sample. Recent advancements in immunological, molecular, and gene analyses using intraocular samples have made it possible to accurately diagnose VRL. As for the management of VRL, local treatments with irradiation and/or intravitreal injections of anti-tumor agents (methotrexate or rituximab) are effective in suppressing intraocular VRL lesions. However, the effect of systemic chemotherapy, with or without brain irradiation, on preventing central nervous system involvements remains controversial. In this review article, we discuss the following concepts based on previous literature and our unpublished results: current ocular imaging examinations such as optical coherence tomography and fundus autofluorescence; immunological, molecular, and gene expression characterization of intraocular biopsies with special attention to flow cytometry; immunoglobulin gene rearrangement assays that use the polymerase chain reaction test; cytokine assays; gene mutations (MYD88, CD79B); and current local and systemic treatments of VRL.
•Vitreoretinal lymphoma (VRL) is a subtype of diffuse large B-cell lymphoma.•Its global incidence is rising, and its diagnosis and treatment remain difficult.•We review methods for the diagnosis and treatment of VRL and future perspectives.•We synthesize clinical findings of our research group and those of other studies.
We report the case of a 35-year-old woman with chronic active Epstein-Barr virus (EBV) infection (CAEBV). She underwent allogeneic bone marrow transplantation (BMT) from an unrelated male donor and ...achieved a complete response. However, her CAEBV relapsed one year after BMT. EBV-infected cells proliferated clonally and revealed a 46XY karyotype. In addition, the infecting EBV strain differed from that detected before BMT. These findings indicated that her disease had developed from donor cells. This is the first report of donor cell-derived CAEBV that recurred after transplantation, suggesting that host factors may be responsible for the development of this disease.
Previous studies have shown that hematopoietic cytokines, including erythropoietin (Epo) and interleukin (IL)-3, activate the Ras GTPase and the downstream Raf/Erk/Elk-1 signaling pathway. Here we ...report that Epo or IL-3 rapidly and transiently activates Rac, a Rho family GTPase, in hematopoietic cell lines, 32D/EpoR-Wt and UT-7. The cytokine-induced activation of Rac was augmented in a 32D/EpoR-Wt clone that inducibly overexpresses the adaptor protein CrkL or the Ras guanine nucleotide exchange factor C3G, which forms a complex with CrkL. Furthermore, the Rac activation was enhanced or inhibited in cells inducibly expressing an activated Ras mutant, H-Ras61L, or a dominant negative Ras mutant, H-Ras17N, respectively. In addition, the cytokine-induced Rac activation was inhibited by a phosphatidyl-inositol 3'-kinase (PI3K) inhibitor, LY294002, which also inhibited the Erk activation. A dominant negative Rac mutant, Rac17N, also inhibited the cytokine-induced activation of Erk as well as Elk-1. On the other hand, activation of Akt downstream of PI3K was found to play an inhibitory role in cytokine activation of Erk/Elk-1. Together, these results indicate that Rac is activated by Epo or IL-3 at downstream of the Ras/PI3K pathway in parallel with Akt and plays a role in activation of the Erk/Elk-1 signaling pathway in hematopoietic cells.
Intracellular signaling mechanisms regulating SDF-1-induced chemotaxis of hematopoietic cells have remained elusive. Here we demonstrate that overexpression of the adaptor molecule CrkL enhances ...SDF-1-induced chemotaxis of hematopoietic BaF3 and 32Dcl3 cells. Overexpression of CrkL also enhanced SDF-1-induced activation of the Raf-1/MEK/Erk signaling pathway as well as that of the small GTPases Ras, Rap1, and Rac, while a dominant negative mutant of Ras or Rac suppressed CrkL-enhanced Erk activation. SDF-1 stimulation induced tyrosine phosphorylation of CrkL, which was inhibited by the Src family kinase inhibitor PP1 or by dominant negative mutants of Lyn, thus indicating that Lyn mediated SDF-1-induced phosphorylation of CrkL. However, inhibition of the Lyn kinase activity failed to affect SDF-1-induced activation of the small GTPases and Erk. On the other hand, SDF-1-induced activation of the Erk signaling pathway as well as chemotaxis was inhibited by overexpression of a CrkL mutant lacking the N-terminal SH3 domain, which mediates interaction with various signaling molecules including guanine nucleotide exchange factors for the Ras and Rho family GTPases. SDF-1-induced chemotaxis was also inhibited by the dominant negative Ras or Rac mutant as well as by the MEK inhibitor PD98059. These results indicate that CrkL mediates SDF-1-induced activation of the Raf-1/MEK/Erk signaling pathway through Ras as well as Rac in hematopoietic cells and, thereby, plays important roles in the induction of chemotactic response.
Arsenic trioxide (ATO) is remarkably effective for treating acute promyelocytic leukemia. Here, we find that ATO treatment of NB4 and K562 leukemic cells induces activation of ASK1. ASK1 activation ...was induced most significantly at low concentrations of ATO, where G2/M arrest but not apoptosis was induced. On the other hand, ATO barely activated ASK1 at high concentrations, where apoptosis as well as activation of JNK and p38 was induced significantly. ATO-induced accumulation of reactive oxygen species (ROS), while the ASK1 activation was suppressed by cotreatment with an antioxidant,
N-acetyl-l-cysteine. Murine embryonic fibroblasts (MEFs) from ASK1-deficient mice were more susceptible to ATO-induced apoptosis than control MEFs. Furthermore, ATO at the low concentration induced significant apoptosis in K562 cells when ASK1 was knocked down by siRNA. These results indicate that ASK1 is activated by ATO through ROS accumulation and may negatively regulate apoptosis in leukemic cells without activating p38 and JNK.
Intraocular lymphoma (IOL) is rare lymphoma that frequently infiltrates the central nervous system (CNS). An optimal treatment has not been established, and its prognosis is quite poor. We treated ...three IOL patients with CNS involvement by concurrent administration of intravenous and intravitreal methotrexate (MTX) injection. The intraocular lesion responded in all patients. One patient achieved complete response (CR), whereas the other 2 patients were in partial response for CNS lesion, added whole brain radiation and achieved CR. In 3 eyes of 2 patients, an intravitreal MTX injection (vMTX) was administered 2 h after a systemic MTX injection (sMTX) and the intravitreal MTX concentration was measured twice: 2 h after sMTX and 24 h after vMTX. The half-life of MTX in the vitreous fluid was estimated to be 12.4–21.5 h by assuming the first-order elimination kinetics. Although the concentration was still high 24 h after vMTX (69.94–82.89 μM), there were no ocular complications. The serum MTX concentration was not influenced by adding vMTX to sMTX. Grade 3 adverse event, leukocytopenia, was observed in only 1 patient. No grade 4 event was observed. Although further evaluation is required, concurrent sMTX and vMTX may be effective for IOL with CNS involvement.
An 88-year-old man with autoimmune hemolytic anemia (AIHA) who had been treated with low dose prednisolone developed a sudden worsening of his anemia accompanied by reactivation of Epstein-Barr virus ...(EBV). We established EBV-infected spontaneous lymphoblastoid cell lines (LCL), performed an enzyme-linked immunosorbent spot assay, and confirmed a significantly suppressed EBV-specific cytotoxic T-cell (CTL) response to the LCL. EBV reactivation might have been brought about by suppressed CTL activity which could have been due to low dose PSL administration or aging. Since the EBV-DNA titer decreased as AIHA improved, we concluded that EBV might have played a role in the development of anemia.
Extranodal NK/T-cell lymphoma (ENKL), nasal type, is rare and the small intestine is quite extraordinary as a primary lesion site. We report a 47-year-old man with ENKL of the small intestine. He was ...referred to our hospital because of bloody stool and the diagnosis was made by double-balloon endoscopy (DBE) of the small intestine without surgical procedure. His clinical stage was IVB and he was categorized in group 4 by prognostic index of ENKL. He went into complete remission (CR) after intensive chemotherapy (DeVIC) and subsequently underwent allogeneic bone marrow transplantation (BMT). Although he remained in CR for about 8 months after BMT, he died of disease recurrence 14 months after the diagnosis was made. ENKL of the small intestine follows a highly aggressive course. We describe the usefulness of DBE for diagnosis and management for ENKL of the small intestine. Additional cases, however, should be accumulated to establish optimal treatment strategy.
The CrkL adaptor protein is involved in signaling from the receptor for erythropoietin (Epo) as well as interleukin (IL)-3 and activates β1 integrin-mediated hematopoietic cell adhesion through its ...interaction with C3G, a guanine nucleotide exchange factor for Rap1. We demonstrate here that Epo as well as IL-3 activates Rap1 in an IL-3-dependent hematopoietic cell line, 32D, expressing the Epo receptor. The cytokine-induced activation of Rap1 was augmented in cells that inducibly overexpress CrkL or C3G. The CrkL-mediated enhancement of cell adhesion was inhibited by expression of a dominant negative mutant of Rap1, Rap1A-17N, whereas an activated mutant of Rap1, Rap1A-63E, activated β1 integrin-dependent adhesion of hematopoietic cells. In 32D cells, Rap1 was also activated by phorbol 12-myristate 13-acetate and ionomycin, which also enhanced cell adhesion to fibronectin, whereas U73122, an inhibitor of phospholipase C, inhibited both cytokine-induced activation of Rap1 and cell adhesion. It was also demonstrated that Rap1 as well as CrkL is involved in signaling from the EpoR endogenously expressed in a human leukemic cell line, UT-7. These results suggest that Epo and IL-3 activate Rap1 at least partly through the CrkL-C3G complex as well as through additional pathways most likely involving phospholipase Cγ and strongly implicate Rap1 in regulation of β1integrin-mediated hematopoietic cell adhesion.
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