Gyeongsin Park

Arginine-Rich Anti-Vascular Endothelial Growth Factor (Anti-VEGF) Hexapeptide Inhibits Collagen-Induced Arthritis and VEGF-Stimulated Productions of TNF-α and IL-6 by Human Monocytes

Vascular endothelial growth factor (VEGF) has been suggested to play a critical role in the pathogenesis of rheumatoid arthritis (RA). We previously identified a novel RRKRRR hexapeptide that blocked the interaction between VEGF and its receptor through the screening of peptide libraries. In this study, we investigated whether anti-VEGF peptide RRKRRR (dRK6) could suppress collagen-induced arthritis (CIA) and regulate the activation of mononuclear cells of RA patients. A s.c. injection of dRK6 resulted in a dose-dependent decrease in the severity and incidence of CIA and suppressed synovial infiltration of inflammatory cells in DBA/1 mice. In these mice, the T cell responses to type II collagen (CII) in lymph node cells and circulating IgG Abs to CII were also dose-dependently inhibited by the peptides. In addition, VEGF directly increased the production of TNF-α and IL-6 from human PBMC. Synovial fluid mononuclear cells of RA patients showed a greater response to VEGF stimulation than the PBMC of healthy controls. The major cell types responding to VEGF were monocytes. Moreover, anti-VEGF dRK6 inhibited the VEGF-induced production of TNF-α and IL-6 from synovial fluid mononuclear cells of RA patients and decreased serum IL-6 levels in CIA mice. In summary, we observed first that dRK6 suppressed the ongoing paw inflammation in mice and blocked the VEGF-induced production of proinflammatory cytokines. These data suggest that dRK6 may be an effective strategy in the treatment of RA, and could be applied to modulate various chronic VEGF-dependent inflammatory diseases.

Identification of a Stroma‐Mediated Wnt/β‐Catenin Signal Promoting Self‐Renewal of Hematopoietic Stem Cells in the Stem Cell Niche

With contrasting observations on the effects of β‐catenin on hematopoietic stem cells (HSCs), the precise role of Wnt/β‐catenin signals on HSC regulation remains unclear. Here, we show a distinct mode of Wnt/β‐catenin signal that can regulate HSCs in a stroma‐dependent manner. Stabilization of β‐catenin in the bone marrow stromal cells promoted maintenance and self‐renewal of HSCs in a contact‐dependent manner, whereas direct stabilization in hematopoietic cells caused loss of HSCs. Interestingly, canonical Wnt receptors and β‐catenin accumulation were predominantly enriched in the stromal rather than the hematopoietic compartment of bone marrows. Moreover, the active form of β‐catenin accumulated selectively in the trabecular endosteum in “Wnt 3a‐stimulated” or “irradiation‐stressed,” but not in “steady‐state” marrows. Notably, notch ligands were induced in Wnt/β‐catenin activated bone marrow stroma and downstream notch signal activation was seen in the HSCs in contact with the activated stroma. Taken together, Wnt/β‐catenin activated stroma and their cross‐talk with HSCs may function as a physiologically regulated microenvironmental cue for HSC self‐renewal in the stem cell niche. STEM CELLS 2009;27:1318–1329

Human AQP5 plays a role in the progression of chronic myelogenous leukemia (CML).

Aquaporins (AQPs) have previously been associated with increased expression in solid tumors. However, its expression in hematologic malignancies including CML has not been described yet. Here, we report the expression of AQP5 in CML cells by RT-PCR and immunohistochemistry. While normal bone marrow biopsy samples (n = 5) showed no expression of AQP5, 32% of CML patient samples (n = 41) demonstrated AQP5 expression. In addition, AQP5 expression level increased with the emergence of imatinib mesylate resistance in paired samples (p = 0.047). We have found that the overexpression of AQP5 in K562 cells resulted in increased cell proliferation. In addition, small interfering RNA (siRNA) targeting AQP5 reduced the cell proliferation rate in both K562 and LAMA84 CML cells. Moreover, by immunoblotting and flow cytometry, we show that phosphorylation of BCR-ABL1 is increased in AQP5-overexpressing CML cells and decreased in AQP5 siRNA-treated CML cells. Interestingly, caspase9 activity increased in AQP5 siRNA-treated cells. Finally, FISH showed no evidence of AQP5 gene amplification in CML from bone marrow. In summary, we report for the first time that AQP5 is overexpressed in CML cells and plays a role in promoting cell proliferation and inhibiting apoptosis. Furthermore, our findings may provide the basis for a novel CML therapy targeting AQP5.

Cell of Origin in AML: Susceptibility to MN1-Induced Transformation Is Regulated by the MEIS1/AbdB-like HOX Protein Complex

Pathways defining susceptibility of normal cells to oncogenic transformation may be valuable therapeutic targets. We characterized the cell of origin and its critical pathways in MN1-induced leukemias. Common myeloid (CMP) but not granulocyte-macrophage progenitors (GMP) could be transformed by MN1. Complementation studies of CMP-signature genes in GMPs demonstrated that MN1-leukemogenicity required the MEIS1/AbdB-like HOX-protein complex. ChIP-sequencing identified common target genes of MN1 and MEIS1 and demonstrated identical binding sites for a large proportion of their chromatin targets. Transcriptional repression of MEIS1 targets in established MN1 leukemias demonstrated antileukemic activity. As MN1 relies on but cannot activate expression of MEIS1/AbdB-like HOX proteins, transcriptional activity of these genes determines cellular susceptibility to MN1-induced transformation and may represent a promising therapeutic target.

Calcineurin Is Expressed and Plays a Critical Role in Inflammatory Arthritis

Calcineurin is a calcium-activated phosphatase to mediate lymphocyte activation and neuron signaling, but its role in inflammatory arthritis remains largely unknown. In this study, we demonstrate that calcineurin was highly expressed in the lining layer, infiltrating leukocytes, and endothelial cells of rheumatoid synovium. The basal expression levels of calcineurin were higher in the cultured synoviocytes of rheumatoid arthritis patients than those of osteoarthritis patients. The calcineurin activity in the synoviocytes was increased by the stimulation with proinflammatory cytokines such as IL-1β and TNF-α. Moreover, rheumatoid arthritis synoviocytes had an enlarged intracellular Ca2+ store and showed a higher degree of [Ca2+]i release for calcineurin activity than osteoarthritis synoviocytes when stimulated with either TNF-α or phorbol myristate acetate. IL-10, an anti-inflammatory cytokine, failed to increase the Ca2+ and calcineurin activity. The targeted inhibition of calcineurin by the overexpression of calcineurin-binding protein 1, a natural calcineurin antagonist, inhibited the production of IL-6 and matrix metalloproteinase-2 by rheumatoid synoviocytes in a similar manner to the calcineurin inhibitor, cyclosporin A. Moreover, the abundant calcineurin expression was found in the invading pannus in the joints of mice with collagen-induced arthritis. In these mice, calcineurin activity in the cultured synovial and lymph node cells correlated well with the severity of arthritis, but which was suppressed by cyclosporin A treatment. Taken together, our data suggest that the abnormal activation of Ca2+ and calcineurin in the synoviocytes may contribute to the pathogenesis of chronic arthritis and thus provide a potential target for controlling inflammatory arthritis.

A Novel Function of Interleukin-10 Promoting Self-Renewal of Hematopoietic Stem Cells

Self‐renewal of hematopoietic stem cells (HSCs) is key to their reconstituting ability, but the factors regulating the process remain poorly understood. Here, we show that Interleukin‐10 (IL‐10), a pleiotropic immune modulating cytokine, can also play a role in regulating HSC self‐renewal. First, a quantitative decrease of primitive hematopoietic cell populations, but not more matured cells, was observed in the bone marrows of IL‐10 disrupted mice as determined by long‐term in vitro cultures or in vivo competitive repopulation assays. In contrast, normal HSCs from 5‐fluorouracil treated marrows cultured on the IL‐10 secreting stroma displayed an enhanced repopulating activity compared with cells grown on control stroma, with ninefold higher numbers of donor‐derived HSCs in the reconstituted recipient marrows. Moreover, limiting dilution transplantation assay demonstrated that exogenous addition of IL‐10 in the stroma‐free cultures of purified Lin−Sca‐1+c‐kit+ cells caused three‐ to fourfold higher frequencies of HSCs in the 5‐day short‐term culture without indirect inhibitory effect of IL‐10 on tumor necrosis factor‐α or interferon‐γ secretion. Interestingly, primitive hematopoietic cells, including Lin−Sca‐1+c‐kit+ or side population cells, expressed the surface receptor for IL‐10, and microenvironmental production of IL‐10 was sharply increased in the osteoblasts lining the trabecular regions of the radiation‐stressed marrow but not in the steady‐state marrows. These results show that IL‐10 may be a ligand that can stimulate self‐renewal of HSCs to promote their regeneration in addition to being a ligand for immune regulation.

Indoleamine 2,3-dioxygenase (IDO) is frequently expressed in stromal cells of Hodgkin lymphoma and is associated with adverse clinical features: a retrospective cohort study

BackgroundRegulation of tumor microenvironment is closely involved in the prognosis of Hodgkin lymphoma (HL). Indoleamine 2,3-dioxygenase (IDO) is an enzyme acting as immune modulator through suppression of T-cell immunity. This study aims to investigate role of IDO in the microenvironment of HL.MethodsA total of 121 cases of HL were enrolled to do immunohistochemistry for IDO, CD163, CD68, CD4, CD8, and FoxP3. Positivity was evaluated from area fractions or numbers of positive cells using automated image analyzer. Correlations between IDO expression and various cellular infiltrates and clinicopathologic parameters were examined and survival analyses were performed.ResultsIDO was expressed in histiocytes, dendritic cells and some endothelial cells with variable degrees, but not in tumor cells. IDO positive cells were more frequently found in mixed cellularity type than other histologic types, and in cases with EBV+, high Ann Arbor stages, B symptoms, and high IPS (all p < 0.05). High IDO expression was associated with inferior survival (p < 0.001) and reflects an independent prognostic factor in nodular sclerosis HL.ConclusionsThis is the first study suggesting that IDO is the principle immunomodulator and is involved to adverse clinical outcomes of HL.

Early apoptosis in CD34+ cells as a potential heterogeneity in quality of cryopreserved umbilical cord blood

The increased use of umbilical cord blood (UCB) raises issues regarding the quality of cryopreserved UCB. This study investigated whether early apoptosis of CD34+ cells is part of the functional heterogeneity of cryopreserved UCB. Annexin V binding of CD34+PI(−) cells showed wide variations in both fresh and cryopreserved UCBs, with greater variation among units frozen for >5 years. Xenotransplantation of sorted cells into non‐obese diabetic severe combined immunodeficient mice demonstrated that the Annexin V assay identified most repopulating activities in UCB units. Thus, early apoptosis of CD34+ cells could influence the outcome of transplantation using cryopreserved UCB.

Ophthalmologic outcomes after chemotherapy and/or radiotherapy in non-conjunctival ocular adnexal MALT lymphoma

In the present study, we evaluated the ophthalmologic outcomes of 24 patients who received chemotherapy and/or radiotherapy for the treatment of non-conjunctival ocular adnexal mucosa-associated lymphoid tissue-type (MALT) lymphoma. Ophthalmologic outcomes were assessed in patients who received chemotherapy and/or radiotherapy from March 2004 until May 2010. Outcomes were determined according to common symptoms following chemotherapy and/or radiotherapy, which consisted of decreased visual acuity, dry eye symptoms, retinopathy, optic neuropathy, increased intraocular pressure, and blepharitis. Nine patients received chemotherapy alone, eight patients received radiotherapy alone, and seven patients received chemotherapy with additional radiotherapy (chemoradiation therapy). Patients treated by chemotherapy alone showed better ophthalmologic outcome scores (mean score, 1.56) than those treated by radiation alone or chemoradiation therapy (mean score, 4.01). In conclusion, the treatment of ocular adnexal lymphoma including radiotherapy showed poor ophthalmologic outcomes due to radiation-induced complications. Recently, many new treatment options have emerged, such as immunotherapy or radioimmunotherapy. In the future study, to select a better treatment modality with fewer complications, well-designed prospective trials with ophthalmologic outcomes are needed.

Intramarrow injection of

Bone marrow mesenchymal stromal cells (MSCs) have been implicated in the microenvironmental support of hematopoietic stem cells (HSCs) and often co-transplanted with HSCs to facilitate recovery of ablated bone marrows. However, the precise effect of transplanted MSCs on HSC regeneration remains unclear because the kinetics of HSC self-renewal in vivo after co-transplantation has not been monitored. In this study, we examined the effects of intrafemoral injection of MSCs on HSC self-renewal in rigorous competitive repopulating unit (CRU) assays using congenic transplantation models in which stromal progenitors (CFU-F) were ablated by irradiation. Interestingly, naïve MSCs injected into femur contributed to the reconstitution of a stromal niche in the ablated bone marrows, but did not exert a stimulatory effect on the in-vivo self-renewal of co-transplanted HSCs regardless of the transplantation methods. In contrast, HSC self-renewal was four-fold higher in bone marrows intrafemorally injected with β-catenin-activated MSCs. These results reveal that naïve MSCs lack a stimulatory effect on HSC self-renewal in-vivo and that stroma must be activated during recoveries of bone marrows. Stromal targeting of wnt/β-catenin signals may be a strategy to activate such a stem cell niche for efficient regeneration of bone marrow HSCs.