ALBERT

Description: Key Points MLL-ENL targets long-term HSCs exclusively to develop leukemia in a novel conditional transgenic mouse through upregulation of Plzf. Plzf is critically involved in the aberrant self-renewal program in HSCs induced by the MLL fusion gene.

Description: Elderly patients (pts) with acute myelogenous leukemia (AML) and high-risk myelodysplastic syndrome (MDS) particularly who are ineligible for allogeneic hematopoietic stem cell transplantation (allo-HSCT) and have disease relapse after allo-HSCT still have a poor prognosis. Thus, the development of novel treatment option providing higher response rate and prolonged survival time for those patients still remains an unmet need. Because not a few clinical and preclinical studies have described a promising value of Wilms Tumor 1 (WT1), a leukemia-associated antigen as a therapeutic target of antileukemia immunotherapy, we conducted a clinical study of novel adoptive immunotherapy using gene-modified autologous lymphocytes expressing WT1-specific T-cell receptor (TCR) for the treatment of refractory AML and high-risk MDS. A multicenter phase 1 study was conducted to assess feasibility, safety and preliminary antileukemia reactivity of patient-derived gene-modified lymphocytes expressing WT1-specific TCR. Antigen-specific TCR-gene transfer may cause a serious autoimmune disease mediated by mispaired TCR between introduced and endogenous TCR α/β chains. To avoid that, we established a retroviral vector system encoding siRNAs for endogenous TCR genes (siTCR vector). We conducted a first-in-human clinical trial employing this siTCR vector. After given written informed consents, mononuclear cells were collected from at most 200ml of peripheral blood (PB) from each patient. Then, proliferating lymphocytes pre-cultured with IL-2, anti-CD3 antibody and RetroNectinTM were infected with a retroviral vector, MS3-WT1-siTCR composed of DNAs encoding WT1235-243/HLA-A*24:02 complex specific TCR-α/β chains and siRNAs against endogenous TCR genes. Expanded gene-modified lymphocytes (WT1-siTCR/T cells) in additional culture for 13-14 more days were harvested and frozen until use. Eligibility included HLA-A*24:02 positive pts with refractory AML or high-risk MDS, 〉 20 y.o, ineligible for allo-HSCT and performance status of 0 to 2. WT1-siTCR/T cells were intravenously infused twice on days 0 and 28. Heteroclitic WT1235-243 ninemer peptide (300mg) emulsified with MontanideTM was given subcutaneously on day 2 and 16 after the second infusion. Besides safety assays, kinetics of WT1-siTCR/T cells in PB, immunological responses and residual leukemia burden determined by qRT-PCR for WT1 mRNA were serially measured until day 58 since the first infusion. Among 12 pts enrolled, 8 pts (5 AML, 3 MDS) with a median age of 68.5 y. received study treatment. Three pts received 2x108 cells/ infusion (cohort 1), 3 received 1x109 cells/ infusion (cohort 2), and 2 received extra-cohort doses. Median follow-up time after the first infusion was 257 days (as June 13, 2016). At the first infusion, all pts contracted progressive disease. Circulatory WT1-siTCR/T cells retaining the target reactivity appeared immediately after each infusion, peaked between 1 to 3 days, and declined thereafter. WT1 peptide vaccination did not seem to affect the transition of infused cells. Values of WT1 mRNA in PB were transiently suppressed in all pts and declined in 4 pts thereafter. Clinical outcomes included one with stable disease and 2 pts with partial remission (PR). In one with PR, the epitope-spreading phenomenon was suggested. In all pts, no serious adverse events associated with infused WT1-siTCR/T cells were observed. Adoptive transfer of autologous WT1-siTCR/T cells was feasible and safe. Although the persistence of infused WT1-siTCR/T cells was limited, infused WT1-siTCR/T cells at least seemed to be involved in the antileukemia reactivity. Disclosures Tawara: Astellas: Honoraria. Akatsuka:Takara Bio Inc.: Consultancy. Nukaya:Takara Bio Inc.: Employment. Takesako:Takara Bio Inc.: Employment.

Description: Hematopoietic stem and progenitor cells, which express CD34 antigen, circulate at a very low frequency in peripheral blood in steady state. CD34+ cells are highly mobilized after myeloablative chemotherapy or the administration of various cytokines such as granulocyte colony-stimulating factor and thrombopoietin (TPO). As TPO is mainly produced by the liver, liver conditions may be associated with hematopoiesis, especially thrombopoiesis. In fact, thrombocytopenia is common in patients with chronic liver diseases. To clarify the association of CD34+ cell mobilization with liver conditions, we examined the number of circulating CD34+ cells in 88 patients with various stages of hepatitis C virus-associated chronic liver diseases; 5 healthy carriers, 43 patients with chronic hepatitis (CH), 19 patients with liver cirrhosis (LC), and 21 patients with LC and hepatocellular carcinoma (HCC). Moreover, to assess the basal number of circulating CD34+ cells, 16 healthy controls were included. The evaluation of CD34+ cells has been carried out by flow cytometry, by applying conventional protocols. The number of circulating CD34+ cells was significantly diminished with progression of liver disease: healthy controls, 3.78 ± 3.93 cells/μL; healthy carrier, 1.89 ± 0.94 cells/μL; CH, 1.49 ± 1.41 cells/μL; LC, 0.66 ± 0.83 cells/μL; and LC with HCC, 0.58 ± 0.19 cells/μL. Next, we analyzed platelet count and number of circulating CD34+ cells before and after living donor liver transplantation (LDLT) in 12 patients who underwent LDLT for LC and/or HCC. A 4-fold increase in platelet level (from 68 x 109/L to 234 x 109/L) and a 5-fold increase in number of circulating CD34+ cells (from 0.78 cells/μL to 3.52 cells/μL) were observed after LDLT. These results suggest that not only thrombopoiesis but also mobilization of CD34+ cells from bone marrow into PB depends on liver conditions.

Description: The regulatory mechanism of human lymphoid differentiation remains less defined. Here we examined how bone marrow stromal cells regulate human early lymphoid differentiation, using human telomerized bone marrow stromal cells that support the generation of CD7+CD56- early T and CD10+CD19+ proB cells from human hematopoietic progenitors. To examine the role of direct contact between hematopoietic progenitors and stromal cells in lymphopoiesis, cultures were performed by inhibiting the cell-cell contact with microporous insert or by incubating hematopoietic progenitors with conditioned medium collected from stromal cell cultures. The separation suppressed B-lineage differentiation to CD10+CD19+ cells, while the generation of CD7+ cells was not significantly influenced. The CD7+ cells generated with or without direct contact with stromal cells similarly had multipotent differentiation capacity for T, B, NK, granulocytic, and monocytic cells but not for erythroid cells in various culture conditions. On the other hand, even CD10+CD19- immature cells had more limited differentiation capacity for T, B, and monocytic cells in various culture conditions, and mostly differentiated toward CD10+CD19+ proB cells on the stromal cells. By time course analysis after coculture on the stromal cells, CD7+CD10- followed by CD10+CD19- and then CD10+CD19+ cells were developed. Some portion of CD7+CD10- and most of CD7-CD10+CD19- cells, upon recultured on stromal cells, differentiated toward CD10+CD19+ cells, but such B-lineage differentiation on the stromal cells was diminished by reculture with conditioned medium. ICAM-1 was expressed on the telomerized stromal cells. Coculture on stromal cells in the presence of LFA-1 neutralizing antibody that blocks the binding to ICAM-1 inhibited the differentiation to CD19+ proB cells. Our findings show that stromal cells support the generation of CD7+ multipotent lymphoid and CD10+ B-biased progenitors by producing soluble factors, but enhances B-lineage differentiation toward CD19+ proB cells in part via LFA-1-mediated direct cell-cell contact. Disclosures: No relevant conflicts of interest to declare.

Description: Hepatic stellate cells are believed to play a key role in the development of liver fibrosis. They undergo a gradual transition from a quiescent, fat-storing phenotype to an activated myofibroblast-like phenotype and then produce high amount of extracellular matrix such as collagen by liver injury. They express mesenchymal markers such as vimentin and desmin, or neural/neuroectodermal markers such as glial fibrillary acidic protein (GFAP). Based on the characteristic phenotype, the embryonic origin of stellate cells is thought to be the septum transversum mesenchyme or neural crest. However, their origin in the adult liver is still unknown. Recently, several studies have reported that crude bone marrow (BM) cells can give rise to hepatic stellate cells. However, since adult BM cells are thought to contain hematopoietic stem cells and mesenchymal stem cells, it is important to clarify which type of stem cells is the true source of hepatic stellate cells. We hypothesized that hepatic stellate cells are derived from hematopoietic stem cells. To test this hypothesis, we generated chimeric mice by transplantation of singe enhanced green fluorescent protein (EGFP)-marked hematopoietic stem cells (Lin− Sca-1+ c-kit+ CD34− cells) into lethally irradiated nontransgenic mice and examined the histology of liver tissues obtained from chimeric mice with carbon tetrahydrochloride (CCl4)-induced injury. Following 12 weeks treatment of CCl4, hepatic nodules and bridging fibrosis developed in all livers. We detected EGFP+ cells in the liver and some of them contained intracytoplasmic lipid droplets, which were proved by oil red O staining. Immunohistochemical analysis demonstrated that 60% of EGFP+ cells were negative for leukocyte common antigen (CD45); however, they expressed vimentin, GFAP and ADAMTS-13, which is a circulating zinc metalloproteinase synthesized in hepatic stellate cells. Moreover, nonparenchymal cell populations were isolated from the livers of chimeric mice with CCl4 treatment and were incubated on noncoated glass slides for 3 days. EGFP+ cells were also positive for type I collagen. These phenotypes are consistent with those of hepatic stellate cells. Our findings suggest that hematopoietic stem cells contribute to the generation of hepatic stellate cells upon liver injury.

Description: Abstract 2830 Introduction Myeloid and lymphoid neoplasms with eosinophilia and abnormalities of PDGFRA, PDGFRB, or FGFR1 is a new major category in the 2008 WHO classification of myeloid malignancies. FIP1L1-PDGFRA fusion gene is currently the most common abnormality in this category, but there are some other fusion genes incorporating part of PDGFRA. In a case of myeloproliferative neoplasms (MPN) with eosinophilia and hepatosplenomegaly, karyotype by G-banding and fluorescence in situ hybridization (FISH) for 4q12 rearrangements indicated a PDGFRA rearrangement other than FIP1L1-PDGFRA, and a novel FOXP1-PDGFRA fusion gene was identified. Case presentation A 44-year-old male visited a clinic because of wet cough for one year. His peripheral blood showed leukocytosis of 43.15 × 109 /L with eosinophilia up to 57.5%, mild erythrocytosis (Hb 17.3 g/dL), and thrombocytopenia of 86 × 109 /L. CT scan of the abdomen revealed hepatosplenomegaly. He was referred to our hospital and received oral PSL (1 mg/kg) first, because pulmonary eosinophilic infiltration was suspected by follow-up CT findings. Pulmonary infiltration and his cough disappeared rapidly in a week, but his leukocytosis with eosinophilia was exacerbated again with PSL tapering. His bone marrow at the time of admission disclosed hypercellular marrow with myeloid hyperplasia and eosinophilia, of which karyotype was 46, XY, t(3:4)(p13;q12), inv(9)(p12q13) in all of 20 metaphases. FISH analysis with tricolor 4q12 rearrangement probe set indicated that PDGFRA was disrupted in 97.3% of his peripheral blood cells. These cytogenetic abnormalities of his bone marrow cells suggested involvement of PDGFRA fusion gene except for FIP1L1-PDGFRA and did not disappear after steroid administration for 2 weeks. After low-dose of imatinib (100 mg/day) was started, he achieved a hematological response within 5 days, and PSL could be gradually tapered off. 3 months after therapy, he obtained complete cytogenetic response (CCyR). He has been in CCyR and free of symptoms for more than 6 months with only low-dose imatinib. Methods and Results Genomic DNA and total RNA were isolated from white blood cells in his peripheral blood at diagnosis. Complementary DNA was synthesized from total RNA. FIP1L1-PDGFRA fusion transcript was proved to be negative by RT-PCR. Molecular cloning with 5′-RACE-PCR revealed a novel mRNA in-frame fusion between exon 23 of FOXP1 and a truncated PDGFRA exon12. Reciprocal PDGFRA-FOXP1 transcripts were confirmed by RT-PCR analysis and FOXP1-PDGFRA genomic DNA sequence was determined with genomic PCR. As in the case with FIP1L1-PDGFRA, the breakpoint of PDGFRA in FOXP1-PDGFRA was located between the two tryptophan (W) residues of the putative WW-domain. Meanwhile, the other breakpoint was near inverted repeat in intron 23 of FOXP1, which is presumed to be very fragile site. By FISH analysis after magnetic cell sorting with MicroBeads, the 4q12 abnormality attributed to FOXP1-PDGFRA fusion gene was detected in granulocytes, but not in CD19-positive B or CD3-positive T cells. Discussion In a case with chronic eosinophilia harboring 46, XY, t(3:4)(p13;q12), inv(9)(p12q13), novel FOXP1-PDGFRA fusion gene was identified. Similar karyotypic abnormality harboring t(3:4)(p13;q12) was reported in a case of MPN with chronic eosinophilia, but responsible fusion gene was not identified (Myint H, et al. Br J Haematol. 1995). FOXP1 is a transcription factor which is implicated in a variety of cellular processes and has a role in immune regulation and carcinogenesis (Wlodarska I, et al. Leukemia. 2005). As a fusion partner of FOXP1, PAX5 and ABL1 are reported in cases with acute lymphoblastic leukemia. Thus, this is a first report showing that FOXP1-PDGFRA fusion gene is involved in hematologic malignancy. It is likely that FOXP1-PDGFRA is constitutively activated tyrosine kinase, which does not depend on dimerization but on the disruption of an autoinhibitory juxtamembrane domain encoded by exon 12 of PDGFRA from its structure. Eosinophilia responded well to low dose of imatinib as observed in CEL with FIP1L1-PDGFRA. Conclusion FOXP1-PDGFRA was identified in CEL for the first time. This is the eighth reported fusion gene associated with PDGFRA in CEL so far. Our patient with FOXP1-PDGFRA promptly responded to low-dose of imatinib as same as other cases with PDGFRA abnormalities. Further investigation is still in progress. Disclosures: No relevant conflicts of interest to declare.

Description: Abstract 2746 Poster Board II-722 Although attention has been paid to the antitumor activity of histone deacetylase (HDAC) inhibitors in hematologic disease, a role for HDAC in normal hematopoiesis has not been clearly defined. Previous study have shown that the potent HDAC inhibitor FK228 (romidepsin, depsipeptide) stimulates IL-3-mediated erythropoiesis in serum-free cultures. Here, we precisely examined the effects of well-tolerated antiepileptic drug valproic acid (VPA) on IL-3-mediated megakaryopoiesis and erythropoiesis in serum-free and serum-containing cultures. After incubation of CD34+ cells in serum-free medium containing IL-3+SCF, CD61+GPA− megakaryocytic, a CD61+GPA+ mixture of megakaryocytic and erythroid, and CD61−GPA+ erythroid precursors were generated. Pharmacological concentration of VPA (100 μg/ml) and FK228 (0.45 ng/ml) remarkably increased the number of CD61+GPA+ cells by 7-fold and 9-fold, respectively. Other populations were also increased by FK228 and VPA. VPA and FK228 enhanced the generation of megakaryocytic and erythroid precursors from more mature CD34+ cell-derived CD36+ erythroid and megakaryocytic precursors. Thus, VPA was found to be as potent as FK228 in stimulating the IL-3-mediated megakaryopoiesis and erythropoiesis. In the presence of GM-CSF+SCF, CD61−GPA+ erythroid precursors were mostly developed. Addition of VPA to the cultures mainly promoted the generation of CD61−GPA+ erythroid precursors, while the generation of megakaryocytic precursors was also moderately enhanced. In serum-containing cultures, there were only low numbers of CD61+ or GPA+ cells detected even in the presence of IL-3+SCF. Nevertheless, addition of VPA to the cultures containing IL-3+SCF increased the numbers of CD61+GPA−, CD61+GPA+, and CD61−GPA+ cells by 3-fold, 18-fold, and 4-fold, respectively from three independent experiments. In megakaryopoiesis and erythropoiesis, GATA-1 and GATA-2 are shown to play important roles in the proliferation and differentiation process, respectively. By quantitative RT-PCR analysis, after incubation of CD34+ cells with IL-3+SCF, GATA-2 m-RNA expression was increased at day1 but returned to initial levels at day3. VPA increased the expression level of GATA-2 gene by 1.6-fold and 1.7-fold at day1 and day3, respectively. While GATA-1 gene expression was remarkably elevated at day1 and day3, its expression was not affected by VPA. Our data reveal a potential for VPA to promote the ability of IL-3 to stimulate megakaryopoiesis and erythropoiesis in serum-free and serum-containing cultures and thus implicate a novel therapeutic approach of epigenetic therapy for treatment of hematologic disease such as myelodysplastic syndrome. Disclosures: No relevant conflicts of interest to declare.

Description: We have previously reported that Notch ligand Delta-1 may enhance the generation of NOD/SCID-repopulating hematopoietic stem cells and thymus-repopulating T cell precursors from cord blood [CB] CD34+CD38- cells. A complex of IL-6/soluble IL-6 receptor is shown to induce the expansion and proliferation of primitive hematopoietic progenitors that express gp130 but not the IL-6 receptor α chain, in mobilized peripheral blood (MPB) as well as in CB. In this study, we explored the interaction between Delta-1 and IL-6/soluble IL-6 receptor fusion protein [FP] in the generation of hematopoietic progenitors from MPB- and CB-derived primitive hematopoietic progenitors. MPB CD34+ Thy-1+ cells were cultured in serum-free medium with SCF, flt-3 ligand, TPO, and IL-3 [4GF], 4GF plus Delta-1, 4GF plus FP, and 4GF plus FP plus Delta-1. Delta-1 was used after immobilized to the culture plates. Freshly isolated cells and cultured cells were assessed for colony-forming ability by replating cells into semisolid medium containing SCF, flt-3 ligand, TPO, IL-3, IL-6, G-CSF, GM-CSF, and EPO. Colonies were counted at day 14. The numbers of BFU-E, CFU-Mix, and CFU-GM were 37-fold, 18-fold, and 135-fold increased, respectively, in cultures with 4GF plus FP, as compared with those in freshly isolated cells. The addition of both Delta-1 and FP to cultures resulted in 216-fold, 22-fold, and 132-fold increases in the numbers of BFU-E, CFU-Mix, and CFU-GM, respectively, relative to freshly isolated cells. Delta-1 did not affect the generation of colony-forming cells in cultures without FP. Thus, Delta-1 and FP synergistically enhanced the generation of BFU-E from primitive hematopoietic progenitors in MPB. In the cultures of CB CD34+CD38- cells with SCF, flt-3 ligand, TPO [3GF], 3GF plus Delta-1, 3GF plus FP, and 3GF plus FP plus Delta-1, the synergistic enhancement by Delta-1 and FP was observed in the generation of BFU-E and CFU-Mix. These data suggest a novel role for interaction between Notch and gp130 signalings in the generation of erythroid progenitors from primitive hematopoietic progenitors.

Description: Abstract 2582 The regulatory mechanism of human early T and B lymphopoiesis has not been well defined. It has been mostly studied, using mouse stromal cell lines, but either T or B lineage cells were developed. We first tested if human telomerase catalytic subunit (hTERT)-transfected telomerized human stromal cells, which have been shown to efficiently support myelopoiesis in serum-containing and serum-free cultures, are able to support the generation of T and B lineage cells from human primitive hematopoietic progenitors. When we examined the relationship of the expression of lymphoid markers CD7, CD19, CD10, and cytoplasmic CD79a (cyCD79a) with CD38 on cord blood CD34+ cells, these antigens were mainly expressed on CD38high population. The CD19+ or CD10+ cell population mostly overlapped with the cyCD79a+ population. The CD19+ or CD10+ population was largely mutually exclusive with the CD7+ population. We therefore isolated CD34+CD38low/-CD7−CD19−CD10− cells to obtain immature hematopoietic progenitors and incubated the cells with the hTERT-stromal cells in the presence of 20%FCSaMEM. After three weeks, CD19−CD10−CD20−VpreB−cyCD79a+ early B, CD19+CD10+CD20+/−VpreB−cyCD79a+ proB, and CD7+CD56−CD2+/−CD1a−cyCD3− proT stage of cells were detected, in addition to myeloid cells. We then examined the effect of cytokines on the generation of the proB and proT cells. Addition of flt3 ligand (flt3L) to the culture led to an increase in the numbers of the early B, proB, and proT cells by 8-, 13- and 12-fold, respectively, while flt3L did not significantly affect their differentiation. On the other hand, SCF or TPO alone did not significantly affect the generation of early B, proB, and proT cells, but, in combination with flt3L, enhanced the generation of these cells. No effects were seen with IL-7. In serum-free cultures without cytokines, considerable number of CD7+ cells was detected, but few or no B lineage cells including cyCD79a+CD19− early B cells were not observed. Nevertheless, flt3L not only enhanced the generation of CD7+ cells but also induced the development of cyCD79a+CD19− early B cells. Our data show the usefulness of telomerized human stromal cells to assess human lymphopoiesis in vitro and suggest an important role for flt3L in human early B and T lymphopoiesis in the human bone marrow environment. Disclosures: No relevant conflicts of interest to declare.

Description: Introduction: Fibrocytes are derived from a subset of monocytes and express mesenchymal markers such as collagen type I (Col I) and hematopoietic markers such as CD45 and CD11b. They also express several chemokine receptors such as CC chemokine receptor (CCR)-1, CCR2, CCR5, CCR7, and CXC chemokine receptor type 4 (CXCR4). They circulate in the peripheral blood (PB) and can be isolated from many fibrotic tissues. Fibrocytes participate in both physiological wound healing and various pathological fibrosis including myelofibrosis, hypertrophic scar, systemic sclerosis, idiopathic pulmonary fibrosis, liver cirrhosis, and progressive kidney disease. In murine and human colitis, fibrocytes are also reported to be associated with the colon fibrosis. It has been described that migration of fibrocytes to the injured sites involves CC chemokine ligand 2 (CCL2)/CCR2 axis in the liver and kidney and CXC chemokine ligand 12 (CXCL12)/CXCR4 axis in the lung. However, there are few reports concerning the role of fibrocytes and their expression of chemokine receptors related to the induction of colon fibrosis. Methods: We generated bone marrow (BM) chimeric mice by transplantation of BM total-nucleated cells, which were isolated from enhanced green fluorescent protein (EGFP)-transgenic mice or CCR2 knockout (KO) mice, into lethally irradiated C57BL/6J-Ly5.1 mice. Two months after BM transplantation, BM chimeric mice were treated with a single intraperitoneal injection of azoxymethane (10 mg/kg body weight) followed by 3 cycles of 1% dextran sulfate sodium (DSS) in the drinking water. We assessed the level of fibrosis in the colon using Sirius red staining and analyzed the presence of BM-derived CD45+CD11b+Col I+ fibrocytes in the colon lamina propria (LP) using immunofluorescence staining and flow cytometry. Furthermore, we investigated the expressions of Col I, transforming growth factor-ß (TGF- ß), matrix metalloproteinases (MMPs), and tissue inhibitor of MMPs (TIMP)-1 in the colon tissues and fibrocytes sorted from colon LP cells after chronic DSS treatment using quantitative real-time RT-PCR. Results: During chronic inflammation, infiltration of CCR2+ BM-derived monocytes and fibrocytes and production of CCL2 in the colon were particularly increased and colon fibrosis was developed in EGFP BM chimeric mice. Two types of fibrocytes, CCR2+CXCR4+Ly6C-F4/80+ fibrocytes and CCR2-CXCR4+Ly6ChighF4/80- fibrocytes, were identified in the colon LP, whereas only the latter fibrocytes were detected in the PB. Adoptive transferred CCR2+Ly6ChighCol I- monocytes migrated to the injured colon and a part of them differentiated into CCR2+Col I+ fibrocytes. In CCR2KO BM chimeric mice, the numbers of monocytes and fibrocytes in the colon LP were significantly decreased and colon fibrosis was attenuated. However, there was no difference in the mRNA expressions of Col I, TGF-ß, and MMPs (MMP-1a, MMP-8, and MMP-13, known as collagenases) in colon tissues between EGFP BM chimeric mice and CCR2KO BM chimeric mice. Improvement of colon fibrosis in CCR2KO BM chimeric mice was associated with the decreased expression of Timp1 mRNA in colon tissues. We analyzed the expression of Timp1 mRNA in CCR2+ cells and CCR2- cells sorted from colon LP cells and found a high expression of Timp1 in CCR2+ monocytes/macrophages and fibrocytes. Conclusions: Circulating CCR2+ monocytes migrate into the inflamed colon via CCL2/CCR2 axis and differentiate into CCR2+Ly6C-F4/80+ fibrocytes, which inhibit collagen degradation and contribute to the development of colon fibrosis by the production of TIMP-1. Disclosures Masuya: Kyowa Hakko Kirin Co., Ltd.: Research Funding. Katayama:Ono Pharmaceutical: Research Funding; Novo Nordisk: Honoraria, Research Funding; Chugai Pharma: Honoraria, Research Funding; Toyama Chemical Co: Research Funding; Sysmex: Honoraria; Mochida Pharmaceutical Co. Ltd.,: Research Funding; Bristol-Myers Squibb: Honoraria; Astellas Pharma: Honoraria, Research Funding; Daiichi Sankyo: Research Funding; Takeda: Honoraria, Research Funding; Teijin Pharma: Research Funding; Eisai: Research Funding; Sumitomo Group: Honoraria, Research Funding; Nippon Shinyaku: Honoraria, Research Funding; Shire: Honoraria; Alexion Pharmaceuticals: Honoraria; Celgene: Honoraria; Taisho Toyama Pharma: Honoraria; Pfizer: Honoraria, Research Funding; Shionogi Pharmaceutical: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; Janssen: Research Funding; Kyowa Hakko Kirin: Honoraria, Research Funding.