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Myelodysplastic syndromes (MDS) are a group of neoplasms characterized by ineffective myeloid hematopoiesis and various risks for leukemia. SRSF2, a member of the serine/arginine-rich (SR) family of splicing factors, is one of the mutation targets associated with poor survival in patients suffering from myelodysplastic syndromes. Here we report the biological function of SRSF2 in hematopoiesis by using conditional knockout mouse models. Ablation of SRSF2 in the hematopoietic lineage caused embryonic lethality, and Srsf2-deficient fetal liver cells showed significantly enhanced apoptosis and decreased levels of hematopoietic stem/progenitor cells. Induced ablation of SRSF2 in adult Mx1-Cre Srsf2(flox/flox) mice upon poly(I):poly(C) injection demonstrated a significant decrease in lineage(-) Sca(+) c-Kit(+) cells in bone marrow. To reveal the functional impact of myelodysplastic syndromes-associated mutations in SRSF2, we analyzed splicing responses on the MSD-L cell line and found that the missense mutation of proline 95 to histidine (P95H) and a P95-to-R102 in-frame 8-amino-acid deletion caused significant changes in alternative splicing. The affected genes were enriched in cancer development and apoptosis. These findings suggest that intact SRSF2 is essential for the functional integrity of the hematopoietic system and that its mutations likely contribute to development of myelodysplastic syndromes.

RUNX1 is an important transcription factor for hematopoiesis. There are multiple alternatively spliced isoforms of RUNX1. The best known isoforms are RUNX1a from use of exon 7A and RUNX1b and c from use of exon 7B. RUNX1a has unique functions due to its lack of C-terminal regions common to RUNX1b and c. Here, we report that the ortholog of human RUNX1a was only found in primates. Furthermore, we characterized 3 Runx1 isoforms generated by exon 6 alternative splicing. Runx1bEx6(-) (Runx1b without exon 6) and a unique mouse Runx1bEx6e showed higher colony-forming activity than the full-length Runx1b (Runx1bEx6(+)). They also facilitated the transactivation of Runx1bEx6(+). To gain insight into in vivo functions, we analyzed a knock-in (KI) mouse model that lacks isoforms Runx1b/cEx6(-) and Runx1bEx6e. KI mice had significantly fewer lineage-Sca1(+)c-Kit(+) cells, short-term hematopoietic stem cells (HSCs) and multipotent progenitors than controls. In vivo competitive repopulation assays demonstrated a sevenfold difference of functional HSCs between wild-type and KI mice. Together, our results show that Runx1 isoforms involving exon 6 support high self-renewal capacity in vitro, and their loss results in reduction of the HSC pool in vivo, which underscore the importance of fine-tuning RNA splicing in hematopoiesis.

Abstract Myelodysplastic syndromes (MDS) are a group of neoplasms that are ineffective in generating multiple lineages of myeloid cells and have various risks to progress to acute myeloid leukemia. Recent genome-wide sequencing studies reveal that mutations in genes of splicing factors are commonly associated with MDS. However, the importance of these splicing factors in hematopoiesis has been unclear and the causal effect of their mutations on MDS development remains to be determined. One of these newly identified genes is SRSF2, and its mutations have been linked to poor survival among MDS patients. Interestingly, most of SRSF2 mutations occur at proline 95 and the majority of these mutations change this proline to histidine (P95H). Given that SRSF2 is a well-characterized splicing factor involved in both constitutive and regulated splicing, we hypothesize that SRSF2 plays an important role in normal hematopoiesis and the SRSF2 mutations induce specific changes in alternative splicing that favor disease progression. We first examined the role of SRSF2 in hematopoiesis by generating Srsf2 null mutation in mouse blood cells via crossing conditional Srsf2 knockout mice (Srsf2f/f) with blood cell-specific Cre transgenic mice (Vav-Cre). The mutant mice produced significantly fewer definitive blood cells (10% of wild type controls), exhibited increased apoptosis in the remaining blood cells, and died during embryonic development. Importantly, we detected no hematopoietic stem/progenitor cells (lineage-/cKit+) in E14 fetal livers of Vav-Cre/Srsf2f/f mice. These results indicate that SRSF2 is essential for hematopoiesis during embryonic development. We next examined the role of SRSF2 in adult hematopoiesis by injecting polyIC into mice that carry a polyIC inducible Cre expression unit. Unexpectedly, after multiple polyIC treatments, the Srsf2f/f mice stayed alive during several months of observation. Time course genotyping analyses of polyIC treated mice revealed an increased rate of incomplete Srsf2 deletion in peripheral blood cells. These observations suggest that Srsf2 ablation did not cause immediate cell lethality in differentiated blood cells, but the gene is indispensable for the function of blood stem/progenitor cells. Since mutations of splicing factors are generally heterozygous in MDS patients, we also examined mice with Srsf2+/- blood cells. No obvious defect of hematopoiesis was observed under normal conditions or in response to stress with 5-FU treatment and sublethal irradiation. To gain molecular insight into the splicing activity of MDS-associated mutant forms of SRSF2, we performed large-scale alternative splicing surveys by using RNA-mediated oligonucleotide annealing, selection, and ligation coupled with next-generation sequencing (RASL-seq) previously developed in our lab, which offers a robust and cost-effective platform for splicing profiling. Compared to vector transduction controls, we found that overexpression of both wild type and P95H SRSF2 induced many, but distinct changes in alternative splicing in lineage-negative bone marrow cells, and importantly, we noted several changes in genes with known roles in hematopoietic malignancies that were uniquely induced by the mutant SRSF2. To further link the mutations to altered splicing in MDS patients, we also applied RASL-seq to a large number of MDS patient samples with or without mutations in SRSF2 or other splicing regulators. The data revealed a specific set of alternative splicing events that are commonly linked to MDS with splicing factor mutations. These findings strongly suggest that many of these mutations in splicing regulators are gain-of-function mutations that are causal to MDS. In conclusion, we report that SRSF2 plays an essential role in hematopoietic stem/progenitor cells and that the MDS-associated mutations in SRSF2 have a dominant effect on RNA alternative splicing. These findings provide functional information and molecular basis of SRSF2 and its MDS-related mutations in hematopoiesis and related clinical disorders. Disclosures: No relevant conflicts of interest to declare.

Fusion protein RUNX1-ETO (AML1-ETO, RUNX1-RUNX1T1) is expressed as the result of the 8q22;21q22 translocation [t(8;21)], which is one of the most common chromosomal abnormalities found in acute myeloid leukemia. RUNX1-ETO is thought to promote leukemia development through the aberrant regulation of RUNX1 (AML1) target genes. Repression of these genes occurs via the recruitment of the corepressors N-COR and SMRT due to their interaction with ETO. Mechanisms of RUNX1-ETO target gene upregulation remain less well understood. Here we show that RUNX1-ETO9a, the leukemogenic alternatively spliced transcript expressed from t(8;21), upregulates target gene Alox5, which is a gene critically required for the promotion of chronic myeloid leukemia development by BCR-ABL. Loss of Alox5 expression reduces activity of RUNX1-ETO9a, MLL-AF9 and PML-RARα in vitro. However, Alox5 is not essential for the induction of leukemia by RUNX1-ETO9a in vivo. Finally, we demonstrate that the upregulation of Alox5 by RUNX1-ETO9a occurs via the C₂H₂ zinc finger transcription factor KLF6, a protein required for early hematopoiesis and yolk sac development. Furthermore, KLF6 is specifically upregulated by RUNX1-ETO in human leukemia cells. This identifies KLF6 as a novel mediator of t(8;21) target gene regulation, providing a new mechanism for RUNX1-ETO transcriptional control.

Of them, mutations in the guanine base of the splice donor signal dinucleotide GT within intron 13 of I ITGB3 i were found in three families with mild to severe bleeding tendency and macrothrombocytopenia, which followed an autosomal dominant inheritance pattern [[3]]. Blood 139(22):3264-3277. https://pubmed.ncbi.nlm.nih.gov/35167650/ 3 Gresele P, Falcinelli E, Giannini S et al (2009) Dominant inheritance of a novel integrin beta3 mutation associated with a hereditary macrothrombocytopenia and platelet dysfunction in two italian families. Dear Editor, Integrins IIb and 3 form a heterodimeric transmembrane receptor to facilitate platelet aggregation and proplatelet formation [[1]]. [Extracted from the article]

A 34-year-old woman was diagnosed with acute promyelocytic leukemia. Chemotherapy was administered following the JALSG APL204 protocol. Induction therapy with all-trans retinoic acid resulted in complete remission on day 49. She developed coccygeal pain from day 18, which spread to the spine and cheekbones and lasted 5 weeks. She had similar bone pain on days 7–10 of the first consolidation therapy and on days 4–12 of the second consolidation therapy. Oral loxoprofen was prescribed for pain relief. On day 33 of the third consolidation, white blood cell and neutrophil counts were 320/μL and 20/μL, respectively. After she developed epigastralgia and hematemesis, she developed septic shock. Gastroendoscopy revealed markedly thickened folds and diffusely damaged mucosa with blood oozing. Computed tomography revealed thickened walls of the antrum and the pylorus. Despite emergency treatments, she died. Bacterial culture of the gastric fluid yielded Enterobacter cloacae and enterococci growth. Collectively, she was diagnosed with phlegmonous gastritis. Retrospective examination of serial bone marrow biopsy specimens demonstrated progressive bone marrow fibrosis, which may have caused prolonged myelosuppression. Thus, evaluation of bone marrow fibrosis by bone marrow biopsy after each treatment cycle might serve as a predictor of persistent myelosuppression induced by chemotherapy. [ABSTRACT FROM AUTHOR]

A 59-year-old man was treated for rheumatoid arthritis (RA) for 12 years with methotrexate (MTX) and prednisolone. After MTX-associated interstitial pneumonia developed, he was treated with cyclophosphamide and prednisolone for 7 months. Arthritis worsened, and tacrolimus was added to the treatment regimen. One month later, he had fever, loss of appetite, and dyspnea on exertion. Blood tests showed pancytopenia with large, atypical lymphocytes. Computed tomography showed mild splenomegaly. Bone marrow examination demonstrated CD20-positive, EBER-positive atypical lymphocytes, and hemophagocytosis. Random skin biopsy led to the diagnosis of intravascular large B-cell lymphoma (IVLBCL). The final diagnosis was a hemophagocytic syndrome-associated variant of IVLBCL. Complete remission was achieved after seven courses of R-CHOP. However, within a month, he complained of dizziness. Magnetic resonance imaging revealed focal infarctions in the cerebellum and around the left lateral ventricle. Central nervous system relapse was suspected. Although salvage chemotherapy (CHASER), whole brain irradiation, and intrathecal injection of cytarabine and prednisolone were temporarily effective, he died. Autopsy revealed infiltration of lymphoma cells in the brain and adrenal glands. To the best of our knowledge, this is the sixth case of IVLBCL and the first case of the hemophagocytic syndrome-associated variant of IVLBCL in RA patients in the literature. [ABSTRACT FROM AUTHOR]

Fusion protein RUNX1-ETO (AML1-ETO, RUNX1-RUNX1T1) is expressed as the result of the 8q22;21q22 translocation [t(8;21)], which is one of the most common chromosomal abnormalities found in acute myeloid leukemia. RUNX1-ETO is thought to promote leukemia development through the aberrant regulation of RUNX1 (AML1) target genes. Repression of these genes occurs via the recruitment of the corepressors N-COR and SMRT due to their interaction with ETO. Mechanisms of RUNX1-ETO target gene upregulation remain less well understood. Here we show that RUNX1-ETO9a, the leukemogenic alternatively spliced transcript expressed from t(8;21), upregulates target gene Alox5, which is a gene critically required for the promotion of chronic myeloid leukemia development by BCR-ABL. Loss of Alox5 expression reduces activity of RUNX1-ETO9a, MLL-AF9 and PML-RARα in vitro. However, Alox5 is not essential for the induction of leukemia by RUNX1-ETO9a in vivo. Finally, we demonstrate that the upregulation of Alox5 by RUNX1-ETO9a occurs via the C2H2 zinc finger transcription factor KLF6, a protein required for early hematopoiesis and yolk sac development. Furthermore, KLF6 is specifically upregulated by RUNX1-ETO in human leukemia cells. This identifies KLF6 as a novel mediator of t(8;21) target gene regulation, providing a new mechanism for RUNX1-ETO transcriptional control. [ABSTRACT FROM AUTHOR]

The article informs about a study on the factors involved in the progression of myelodysplastic syndrome (MDS). The study informs about the mutations of runt homology domain of RUNX1 that as an evident aspect present in the patients with MDS. It includes information on MDS patients as they have C-terminal truncation mutations that lack a transcription regulatory domain and have increased DNA binding through the runt homology domain.

Myelodysplastic syndrome (MDS) is a clonal disorder of hematopietic stem cells characterized by ineffective hematopoiesis, peripheral blood cytopenia, morphologic dysplasia, and susceptibility to acute myeloid leukemia. Several mechanisms have been suggested as causes of MDS: unbalanced chromosomal abnormalities reflecting a gain or loss of chromosomal material, point mutations of transcription factors, and inactivation of p53. However, appropriate animal models that mimic MDS have long been lacking. We recently reported a novel murine model of MDS that recapitulates trilineage dysplasia and transformation to AML. In this review, we summarize the animal models of MDS and discuss the molecular bases of MDS as well as those of leukemia and myeloproliferative disorders (MPD). J. Cell. Physiol. 219: 529–534, 2009. © 2009 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Erythroblasts (EBL) are normally not observed in peripheral blood, but may be found in patients suffering from a variety of severe diseases. The detection of EBL in peripheral blood has been shown to be associated with a poor prognosis. However, the clinical significance of peripheral erythroblastosis after hematopoietic stem cell transplantation (HSCT) has not been evaluated. We retrospectively analyzed the records of 161 patients who underwent HSCT at our hospital from June 1995 to October 2001. EBL at any level were detected in 94% of the patients. Forty-four and 11 patients experienced erythroblastosis exceeding 200 and 1,000/ul, respectively. The erythroblast count was higher in patients who died than in the survivors (geometric mean value 184 vs. 100/ul, P  = 0.01). High-level erythroblastosis ( > 1,000/ul) within 180 days after HSCT was associated with an extremely poor prognosis (median survival 22.5 days). Among the possible confounding factors, the use of total body irradiation (RR 2.35, 95% CI 1.22 - 4.54, P  = 0.011) and the disease status before transplantation (RR 2.51, 95% CI 1.15 - 5.49, P  = 0.021) were independent significant factors for erythroblastosis after HSCT. As for post-transplant events, a high EBL concentration was frequently preceded by graft-vs.-host disease, thrombotic microangiopathy, hypoxia, and hematological relapse. [ABSTRACT FROM AUTHOR]

BACKGROUND Splenic abscess is a rare infectious disease that occurs after bloodstream infection and trauma. It has become more common due to an increase in the number of immunocompromised patients. They typically present with round cystic lesions demonstrated by ultrasonography, computed tomography (CT), and magnetic resonance imaging (MRI). Clostridioides difficile (formerly Clostridium difficile) is a well-known cause of pseudomembranous colitis, but extraintestinal manifestations are very rare. To the best of our knowledge, only 9 cases of splenic abscess due to C. difficile have been reported in the literature. CASE REPORT A 90-year-old man presented with weight loss, fever, and abdominal pain. Contrast-enhanced CT revealed splenomegaly with irregular hypodense nodules. Image-guided biopsy or drainage was not performed for a technical reason. MRI showed atypical nodules with mixed high and low signals on both T1- and T2-weighted images, which were inconclusive. A laparoscopic splenectomy was performed, which resulted in partial removal due to severe adhesion of the spleen to the surrounding tissues. Cultures of splenic pus yielded C. difficile, Enterococcus faecium, and Bacteroides fragilis. Pathological examination of the spleen showed widespread abscesses with hemorrhage and necrosis, leading to the diagnosis of splenic abscesses. Intravenous administration of vancomycin, clindamycin or metronidazole was ineffective. He died of fatal arrhythmia 5 months after the initial diagnosis of splenic abscess. CONCLUSIONS Splenic abscess can present with atypical imaging findings owing to chronic inflammation, bleeding, and necrosis. Although polymicrobial, this is the tenth reported case of splenic abscess caused by C. difficile.

BACKGROUND Anorectal infections occur in 5% to 9% of patients with hematological malignancies, including acute myeloid leukemia, and cause febrile neutropenia and sepsis. Surgical treatments of anorectal abscesses tend to be avoided in patients with leukemia owing to persistent neutropenia and bleeding risks. CASE REPORT A 56-year-old man presented with an ischiorectal abscess. Preoperative laboratory test results revealed leukocytopenia and anemia. He was diagnosed with acute myeloid leukemia. He developed septic shock. Antibiotic treatment was ineffective, and fever persisted. One week later, the abscess was treated by incision and drainage. Two days later, induction chemotherapy was initiated. No pus was drained; cellulitis spread to both buttocks. Pain worsened, and oxycodone was administered. Achievement of complete remission failed. Reinduction therapy was started, followed by fistulotomy of the abscess with extensive debridement of cellulitis on day 6. Granulation was observed on day 17. The patient's fever resolved on day 21. Although hematopoietic recovery was observed, bone marrow examination demonstrated partial remission. Two additional courses of chemotherapy were administered. Abscess recurrence was not observed, even during febrile neutropenia. The surgical wound shrank to a skin defect along the gluteal cleft. He achieved complete remission and was transferred to another hospital, where he underwent 3 allogeneic stem cell transplants. He died of leukemia progression. CONCLUSIONS Surgical treatments can prevent fatal progression of anorectal abscess, even during neutropenia. Incision and drainage are suitable for fluctuant abscesses. For a non-fluctuant abscess aggravated by sepsis and cellulitis, it is worth considering more invasive surgical interventions, including debridement and fistulotomy.

BACKGROUND Syphilis is a sexually transmitted disease caused by the pathogen Treponema pallidum. Prevalence continues to rise, especially among men who have sex with men (MSM). Due to changes in patterns of sexual activity, manifestations of the disease are highly variable. CASE REPORT A 27-year-old male visited the hospital for a low-grade fever and tender 5-cm mass in the right side of his neck. His right tonsil was swollen and covered with a white coating. Levofloxacin was prescribed, but ineffective. The patient's levels of liver function enzymes increased gradually. Systemic magnetic resonance imaging (MRI) revealed bilateral cervical lymphadenopathy with right predominance, a right pulmonary nodule, and a periportal lymph node, suggestive of malignant lymphoma. However, a biopsy of the right cervical lymph node showed nonspecific inflammation. Preoperative rapid plasma reagin (RPR) and T. pallidum latex agglutination (TPLA) tests were positive. The patient was MSM and reported oral sex with many sexual partners. A diagnosis of secondary syphilis was made. Oral amoxicillin was effective, and all symptoms other than periportal lymph node resolved. CONCLUSIONS Tonsillitis, cervical lymphadenopathy, and lung lesions can be manifestations of secondary syphilis. A detailed history, pathology, and serology are crucial for diagnosis.

A 35-year-old male was diagnosed with chronic myeloid leukemia in the chronic phase and was prescribed 100 mg daily dasatinib. However, dasatinib was discontinued due to thrombocytopenia, and within six months, the disease progressed to the lymphoid blastic phase. Hyper-cyclophosphamide, vincristine, adriamycin and dexamethasone chemotherapy combined with 140 mg dasatinib or 600 mg imatinib was prescribed. The two inhibitors were soon discontinued due to severe thrombocytopenia and jaundice, respectively. Myelosuppression persisted subsequent to the nadir. Bone marrow (BM) aspiration and biopsy revealed hypercellular marrow filled with blasts. Sequencing of the leukemia cells revealed overlapping peaks for the wild-type sequence and the T315I mutant sequence. The patient was treated with 500 mg bosutinib (which was later reduced to 300 mg) for pretransplant cytoreduction. After 5 months, the patient's spleen exhibited a reduction in volume and the percentage of blasts in the BM decreased from 96.1 to 17.5%. The patient successfully underwent cord blood transplantation. The patient has been disease-free for 5 months subsequent to transplantation. This case suggests that bosutinib may be effective for cytoreduction prior to stem cell transplantation, unless the leukemia cells consistently harbor the T315I mutation.

An 85-year-old woman underwent emergent splenectomy due to left abdominal pain and active bleeding in a massively enlarged spleen. The histological diagnosis was splenic marginal zone lymphoma (SMZL). A prolonged activated partial thromboplastin time (APTT) was noted, and additional tests led to the diagnosis of type 2A-like acquired von Willebrand syndrome (AVWS). An APTT cross mixing test ruled out the presence of inhibitors. She received eight courses of rituximab monotherapy. The coagulation data showed no improvement, possibly because the lymphoma showed a poor response to the treatment. AVWS rarely causes bleeding in solid organs. This is the first case of SMZL with AVWS diagnosed via splenic bleeding.

A 47-year-old woman with ulcerative colitis (UC) was admitted to our hospital for renal dysfunction and progressive anemia. Colonoscopy revealed intestinal lesions and pathological findings showed intravascular large B-cell lymphoma (IVLBCL). According to the polymerase chain reaction analysis of sequential rectal specimens, we concluded that she suffered from intestinal BCL, not UC. After chemotherapy, her renal function progressed to nephrotic syndrome. The pathological findings of renal biopsy specimens indicated membranoproliferative glomerulonephritis (MPGN). Chemotherapy was continued and led to the remission of BCL and MPGN. We herein describe the first case of intestinal IVLBCL mimicking UC with secondary MPGN.

A 47-year-old woman presented with persistent dysphagia. A gastroendoscopy revealed massive esophageal candidiasis, and oral miconazole was prescribed. Three weeks later, she returned to our hospital without symptomatic improvement. She was febrile, and blood tests showed leukocytosis (137,150 /μL, blast 85%), anemia and thrombocytopenia. She was diagnosed with acute myeloid leukemia (AML). She received chemotherapy and antimicrobial agents. During the recovery from the nadir, bilateral ocular candidiasis was detected, suggesting the presence of preceding candidemia. Thus, esophageal candidiasis can be an initial manifestation of AML. Thorough examination to detect systemic candidiasis is strongly recommended when neutropenic patients exhibit local candidiasis prior to chemotherapy.

High levels of HES1 expression are frequently found in BCR-ABL(+) chronic myelogenous leukemia in blast crisis (CML-BC). In mouse bone marrow transplantation (BMT) models, co-expression of BCR-ABL and Hes1 induces CML-BC-like disease; however, the underlying mechanism remained elusive. Here, based on gene expression analysis, we show that MMP-9 is upregulated by Hes1 in common myeloid progenitors (CMPs). Analysis of promoter activity demonstrated that Hes1 upregulated MMP-9 by activating NF-κB. Analysis of 20 samples from CML-BC patients showed that MMP-9 was highly expressed in three, with two exhibiting high levels of HES1 expression. Interestingly, MMP-9 deficiency impaired the cobblestone area-forming ability of CMPs expressing BCR-ABL and Hes1 that were in conjunction with a stromal cell layer. In addition, CMPs expressing BCR-ABL and Hes1 secreted MMP-9, promoting the release of soluble Kit-ligand (sKitL) from stromal cells, thereby enhancing proliferation of the leukemic cells. In accordance, mice transplanted with CMPs expressing BCR-ABL and Hes1 exhibited high levels of sKitL as well as MMP-9 in the serum. Importantly, MMP-9 deficiency impaired the development of CML-BC-like disease induced by BCR-ABL and Hes1 in mouse BMT models. The present results suggest that Hes1 promotes the development of CML-BC, partly through MMP-9 upregulation in leukemic cells., (© 2014 by The American Society of Hematology.)

Myeloid malignancies consist of acute myeloid leukemia (AML), myelodysplastic syndromes (MDS) and myeloproliferative neoplasm (MPN). The latter two diseases have preleukemic features and frequently evolve to AML. As with solid tumors, multiple mutations are required for leukemogenesis. A decade ago, these gene alterations were subdivided into two categories: class I mutations stimulating cell growth or inhibiting apoptosis; and class II mutations that hamper differentiation of hematopoietic cells. In mouse models, class I mutations such as the Bcr-Abl fusion kinase induce MPN by themselves and some class II mutations such as Runx1 mutations induce MDS. Combinations of class I and class II mutations induce AML in a variety of mouse models. Thus, it was postulated that hematopoietic cells whose differentiation is blocked by class II mutations would autonomously proliferate with class I mutations leading to the development of leukemia. Recent progress in high-speed sequencing has enabled efficient identification of novel mutations in a variety of molecules including epigenetic factors, splicing factors, signaling molecules and proteins in the cohesin complex; most of these are not categorized as either class I or class II mutations. The functional consequences of these mutations are now being extensively investigated. In this article, we will review the molecular basis of hematological malignancies, focusing on mouse models and the interfaces between these models and clinical findings, and revisit the classical class I/II hypothesis.

Leukocyte mono-immunoglobulin (Ig)-like receptor 5 (LMIR5)/CD300b is a DAP12-coupled activating receptor predominantly expressed in myeloid cells. The ligands for LMIR have not been reported. We have identified T cell Ig mucin 1 (TIM1) as a possible ligand for LMIR5 by retrovirus-mediated expression cloning. TIM1 interacted only with LMIR5 among the LMIR family, whereas LMIR5 interacted with TIM4 as well as TIM1. The Ig-like domain of LMIR5 bound to TIM1 in the vicinity of the phosphatidylserine (PS)-binding site within the Ig-like domain of TIM1. Unlike its binding to TIM1 or TIM4, LMIR5 failed to bind to PS. LMIR5 binding did not affect TIM1- or TIM4-mediated phagocytosis of apoptotic cells, and stimulation with TIM1 or TIM4 induced LMIR5-mediated activation of mast cells. Notably, LMIR5 deficiency suppressed TIM1-Fc-induced recruitment of neutrophils in the dorsal air pouch, and LMIR5 deficiency attenuated neutrophil accumulation in a model of ischemia/reperfusion injury in the kidneys in which TIM1 expression is up-regulated. In that model, LMIR5 deficiency resulted in ameliorated tubular necrosis and cast formation in the acute phase. Collectively, our results indicate that TIM1 is an endogenous ligand for LMIR5 and that the TIM1-LMIR5 interaction plays a physiological role in immune regulation by myeloid cells.

Myelodysplastic syndrome (MDS) is a hematopoietic stem-cell disorder characterized by trilineage dysplasia and susceptibility to acute myelogenous leukemia (AML). Analysis of molecular basis of MDS has been hampered by the heterogeneity of the disease. Recently, mutations of the transcription factor AML1/RUNX1 have been identified in 15% to 40% of MDS-refractory anemia with excess of blasts (RAEB) and MDS/AML. We performed mouse bone marrow transplantation (BMT) using bone marrow cells transduced with the AML1 mutants. Most mice developed MDS and MDS/AML-like symptoms within 4 to 13 months after BMT. Interestingly, among integration sites identified, Evi1 seemed to collaborate with an AML1 mutant harboring a point mutation in the Runt homology domain (D171N) to induce MDS/AML with an identical phenotype characterized by marked hepatosplenomegaly, myeloid dysplasia, leukocytosis, and biphenotypic surface markers. Collaboration between AML1-D171N and Evi1 was confirmed by a BMT model where coexpression of AML1-D171N and Evi1 induced acute leukemia of the same phenotype with much shorter latencies. On the other hand, a C-terminal truncated AML1 mutant (S291fsX300) induced pancytopenia with erythroid dysplasia in transplanted mice, followed by progression to MDS-RAEB or MDS/AML. Thus, we have developed a useful mouse model of MDS/AML that should help in the understanding of the molecular basis of MDS and the progression of MDS to overt leukemia.

This prospective study evaluates the safety and efficacy of pravastatin for the treatment of chronic graft-versus-host disease (GVHD). We included 18 patients with refractory chronic GVHD. Oral pravastatin was started at 10 mg/day, and the dose was increased up to 40 mg/day in 4 weeks. This maximum dose was administered over 8 weeks. There were no severe adverse events caused by pravastatin. A clinical response was observed in the skin score in two patients, mouth score in five patients, eye score in two patients, liver score in three patients, platelet count score in one patient, and weight loss in two patients. The overall response rate was 28%. Immunophenotypic analyses showed that T-helper (Th)1 cells were dominant in all but one patient before treatment and that the Th1/Th2 ratio tended to be lower in the responders than in the nonresponders. A randomized controlled trial is warranted to evaluate the efficacy of pravastatin against chronic GVHD.

Thrombotic microangiopathy (TMA) is a microvascular disorder characterized by platelet aggregation and hemolytic anemia. In the setting of bone marrow transplantation (BMT), ischemic colitis due to TMA is difficult to differentiate from acute graft-versus-host disease. We report a 32-year-old man who presented ischemic colitis due to TMA after unrelated BMT for myelodysplastic syndrome. He suffered from treatment-resistant bloody diarrhea, and died of renal failure and Aspergillus pleuritis on day 253 post-BMT. Autopsy revealed endothelial injuries of arterioles and ischemic changes in the intestines and kidneys. Clinical and pathological characteristics of ischemic colitis due to BMT-associated TMA are described.

We report a 21-year-old-man, with myositis as a manifestation of chronic graft-versus-host-disease (GVHD). He was diagnosed as having acute myelogenous leukemia at the age of 18 years, and had bone marrow transplantation (BMT) two years after the onset of the disease. Cutaneous manifestation of acute GVHD appeared on the twelfth day following BMT, which responded to prednisolone. Thereafter, GVHD has been well-controlled except for mild liver dysfunction which was thought to be a sign of chronic GVHD. Eleven months after BMT, he enjoyed snowboarding for two days from morning till night. Two days later, he experienced muscle swelling with pain and fever, which gradually worsened for which he was admitted to our hospital. Neurological examination revealed severe proximal and distal muscle swelling with fever and tenderness in all extremities. Mild, symmetrical, proximal weakness was observed in all four limbs. Severity of muscle swelling and its generalized nature restricted the movements of shoulder-, elbow- and ankle-joints and he was unable to walk. Laboratory investigations revealed creatine kinase (CK) of 7,860 IU/L, C-reactive protein (CRP) of 21.5 mg/dL and raised biliary enzymes. MRI generated high intensity signals from the swollen muscles. Muscle biopsy examination of involved areas showed severe interstitial edema and mononuclear cells infiltration. Macrophages were scattered through out the perimysium and endomysium. On the other hand, T cells and B cells were localized to the endomysium. Although a lot of CD8 positive T cells were seen adjacent to non-necrotic fibers, none of them was obviously invading the non-necrotic fibers. Perifascicular atrophy was not seen. Symptoms gradually worsened over two weeks or so when prednisolone was started to which he responded rapidly. While tapering steroids, the symptoms relapsed on resuming aggressive exercise. Resumption of the treatment regime promptly controlled the symptoms. The cause of myositis as a manifestation of chronic GVHD is unclear. T-cell or B-cell dysfunction, collagen-vascular-like processes, viral infection and direct damage by radiation or chemotherapy have been supposed to involve in the disease process. Our case suggests that aggressive muscular exercise could play as a initiator of myositis as a manifestation of chronic GVHD.

A male patient had a relapse of myelodysplastic syndrome (MDS) 2 years after BMT from a female matched unrelated donor. Conventional cytogenetics, FISH, and short-tandem repeat chimerism analysis proved a relapse of donor origin. He underwent reduced-intensity BMT after a conditioning with fludarabine and busulfan, since he had impaired renal, liver, and pulmonary functions. Chimerism analysis on day 28 after the second BMT showed mixed chimerism of the first and the second donors, which later turned to full second-donor chimerism on day 60. He developed grade II acute GVHD of the skin and cytomegalovirus reactivation, but both were improved with methylprednisolone and ganciclovir, respectively. He remains in complete remission 6 months after the second BMT. Reduced-intensity second BMT from an alternative donor appeared to be a tolerable treatment option for donor-derived leukemia/MDS after the first conventional transplantation., (Copyright 2003 Wiley-Liss, Inc.)

Polymerase chain reaction (PCR) is a sensitive method for detection of Aspergillus DNA in bronchoalveolar lavage fluid, but it has not yet been able to distinguish infection from contamination. We have established a technique to quantify Aspergillus DNA using a real-time PCR method to resolve this problem, and we report herein a successful application of real-time PCR to diagnose invasive pulmonary aspergillosis by comparing the amount of Aspergillus DNA in bronchial lavage fluid from an affected area to that from an unaffected area. This novel tool will provide rapid, sensitive, and specific diagnosis of pulmonary aspergillosis., (Copyright 2002 Wiley-Liss, Inc.)