SOCS1 and SOCS3 are expressed in mononuclear cells in human cytomegalovirus viremia after allogeneic hematopoietic stem cell transplantation.

BACKGROUND: The expression of the SOCS genes in cytomegalovirus (CMV) viremia after hematopoietic stem cell transplantation (HSCT) remains largely unexplored. METHODS: Using quantitative RT-PCR of mononuclear cells, we conducted pairwise comparison of SOCS1 and SOCS3 expression levels among a healthy donor group (N=55), a pre-HSCT group (N=17), and the recipient subgroup (N=107), which were divided according to the occurrence of CMV viremia and acute graft-versus-host disease (aGVHD). RESULTS: Compared to that in the healthy donor group, SOCS1 expression was higher in the CMV+ subgroup, especially in the CMV+GVHD- group, but decreased in the other subgroups. When compared to the expression in the pre-HSCT group, SOCS1 expression was significantly higher in the CMV+ subgroup, especially in the CMV+GVHD+ subgroup. Meanwhile, compared to that in the healthy donor group, SOCS3 expression was significantly lower in all other groups. The CMV-GVHD- subgroup showed significantly lower SOCS3 expression compared to the CMV+ subgroup, the CMV+GVHD+ subgroup, and the CMV+GVHD- subgroup. CONCLUSION: We report differential expression of SOCS genes according to CMV viremia with acute GVHD occurrence after HSCT, suggesting that regulation of SOCS expression is associated with CMV viremia.

Restoration of natural killer cell cytotoxicity by VEGFR-3 inhibition in myelogenous leukemia.

Acute myeloid leukemia (AML) cells in vivo are constantly exposed to lymphangiogenic cytokines such as VEGF-C. However, it is poorly understood how the VEGF-C signaling modulates the immune functions in the tumor microenvironment. We have previously reported that natural killer (NK) cells in AML patients strongly upregulated VEGFR-3, the major VEGF-C receptor, and that the VEGFR-3 expression level in NK cells inversely correlates with their cytotoxic potential. These findings have led us to hypothesize that VEGFR-3 inhibition may reinstate the cytotoxic capacity of the AML-associated NK cells. To address this hypothesis, we employed a pharmaceutical approach to block the VEGFR-3 function in the murine model of syngeneic myelogenous leukemia. Using various molecular and cellular analyses, we assessed the correlation between VEGFR-3 inhibition and NK cell cytotoxicity. Indeed, we found that leukemic environment is highly enriched with lymphangiogenic stimuli, and that VEGFR-3 inhibition restored NK cell killing function with an increased IFN-γ level, providing a therapeutic implication of VEGFR-3 against AML. Together, we demonstrate the therapeutic value of functional modulation of NK cells by blocking VEGFR-3, and provide a possibility of advanced therapeutic approaches using immune cells against myelogenous leukemia.

High ALDHdim-expressing CD34+CD38- cells in leukapheresed peripheral blood is a reliable guide for a successful leukemic xenograft model of acute myeloid leukemia.

The primary human acute myeloid leukemia (AML) cell injection xenograft mouse model is used to investigate multimodal therapies and drug screening on tumor growth. Since xenograft models using human cell lines to examine drug response are not correlated with the clinical outcomes observed in patients, a xenograft model using primary human cells has been used as a more appropriate model with which to minimize this problem. Although bone marrow (BM) cells from patients are often regarded as superior sources to establish xenograft models due to the high frequency of stem cell populations, there is a fatal drawback; only small volumes can be obtained and used for the generation of the leukemic xenograft model. Indeed, longevity of AML characteristics, as well as sufficient stem cells in the xenograft model, should be guaranteed to analyze the therapeutic response to a drug. Therefore, we examined whether leukapheresed peripheral blood (LPB) consists of reliable leukemic stem cells (LSCs) and ALDHdim­expressing CD34+CD38- cells, and functions in grafting human AML with virulence compared to that of BM. LPB cells showed an advantage for the xenograft mouse model with AML cell homing, engraftment and a high human ALDHdim-expressing CD34+CD38- cell population, suggesting an alternative cell source to BM. Overall, this xenograft model using LPB offers the possibility of overcoming the small volume limitation of BM and prevents individual variation by using a single LPB sample. This result is noteworthy in identifying cell sources capable of generating a stable xenograft model.

Combinatorial molecular marker assays of WT1, survivin, and TERT at initial diagnosis of adult acute myeloid leukemia.

High levels of expression of Wilms' tumor gene 1 (WT1), survivin, or telomerase reverse transcriptase (TERT) genes are introduced as leukemia-associated targets predicting clinical outcome. We prospectively investigated the leukemia-associated gene transcripts by real-time quantitative polymerase chain reaction from 151 adult patients with AML associated with the patients' clinical characteristics. The maximum levels of each gene in bone marrow were 64.4-, 8.1-, and 3.9-fold higher than those in the normal control, respectively. In contrast to the WT1 and TERT levels, survivin showed comparatively higher expression in the unfavorable cytogenetic group of patients. We found a significant difference in survivin levels between the CR and non-CR groups (P = 0.0237). TERT expression levels were higher in patients who had a greater number of peripheral blood leukemic blasts at diagnosis (P = 0.0191). Non-MRC subtypes and patients without specific mutations were the most powerful predictive factors for a better CR rate, by multivariate analyses. The lower levels of both WT1 and survivin co-expression (P = 0.0129) and both survivin + TERT co-expression (P = 0.0115) were significant factors for better OS. Besides lower initial levels of serum ferritin (P = 0.0401), lower levels of WT1 (P = 0.0438) and survivin (P = 0.0401), lower levels of both WT1 and survivin co-expression (P = 0.0031), and the three-gene combination of lower WT1 + survivin + TERT (P = 0.0454) were powerful predictive factors for better EFS. As our findings were based on a single disease entity, that is, adult AML, they suggest that the expression of these genes may be critical for the immunobiology of AML to influence the clinical outcome in various ways.

Expression of SOCS1 and SOCS3 genes in human graft-versus-host disease after allogeneic hematopoietic stem cell transplantation.

BACKGROUND: Suppressor of cytokine signaling genes (SOCS) are regarded as pivotal negative feedback regulators of cytokine signals, including the interferon-gamma (IFN-γ), granulocyte-colony stimulating factor, and interleukin families, released by T cells. A detailed understanding of the involvement of SOCS genes in graft-versus-host disease (GVHD) is critical to effectively manage GVHD, yet their expression patterns among recipients remain largely unexplored. METHODS: Expression levels of SOCS1 and SOCS3 were determined by real-time quantitative reverse transcription PCR (qRT-PCR) in patients with acute GVHD (aGVHD) and chronic GVHD (cGVHD), in a severity-dependent manner, after allogeneic hematopoietic stem cell transplantation (HSCT). A total of 71 recipients with AML (N=40), ALL (N=12), myelodysplastic syndromes (MDS; N=10), chronic myelogenous leukemia (CML; N=2), severe aplastic anemia (SAA; N=5), or others (N=2), who received allogeneic HSCT from human leukocyte antigen-identical siblings or unrelated donors between 2009 and 2011, were included in the present study. RESULTS: Overall, the expression levels of SOCS1 decreased in recipients with grade II to IV aGVHD and cGVHD when compared to normal donors and non-GVHD recipients. Interestingly, the expressions of SOCS1 decreased significantly more in cGVHD than in aGVHD recipients (P=0.0091). In contrast, SOCS3 expressions were similarly reduced in all the recipients. CONCLUSION: This is the first study to show that SOCS1 and SOCS3 are differentially expressed in recipients following allogeneic HSCT, suggesting a prognostic correlation between SOCS genes and the development of GVHD. This result provides a new platform to study GVHD immunobiology and potential diagnostic and therapeutic targets for GVHD.

A VEGFR-3 antagonist increases IFN-γ expression on low functioning NK cells in acute myeloid leukemia.

PURPOSE: Although the importance of vascular endothelial growth factor receptor (VEGFR)-3 has been demonstrated in acute myeloid leukemia (AML), the role of VEGFR-3 in functioning natural killer (NK) cells remains largely unexplored. NK cells can destroy cancer cells by releasing the cytokine interferon (IFN)-γ, but NK cells in AML patients (AML NK cells) have low cytolytic activity. In the present study, we investigated whether lymphatic markers including VEGFR-3 are expressed on low-functioning AML NK cells and VEGFR-3 antagonist can restore expression of IFN-γ in NK cells. METHODS: Samples from 67 de novo AML patients and 34 healthy donors were analyzed for lymphatic markers expression using RT-PCR, flow cytometry, and immunostaining. For the cytotoxicity assays, K562 cells and AML NK cells were used as target and effector cells, respectively. To block VEGFR-3, MAZ51 was added to NK cells, which were then subjected to FACS analysis. RESULTS: Compared with NK cells from healthy donors (healthy NK cells), AML NK cells exhibited higher levels of VEGFR-3 and lower expression of IFN-γ. VEGFR-3-expressing AML NK cells were less potent than healthy NK cells in terms of killing K562 cells. The level of IFN-γ in AML NK cells was increased by VEGFR-3 antagonist treatment, indicating the functional relevance of VEGFR-3 in IFN-γ-secreting NK cells. CONCLUSION: Collectively, our data suggest a relationship between VEGFR-3 and IFN-γ expression in NK cells and raise the possibility of advanced therapeutic approaches involving VEGFR-3 antagonist treatment prior to NK immune cell therapy in AML.

Host CD25+CD4+Foxp3+ regulatory T cells primed by anti-CD137 mAbs inhibit graft-versus-host disease.

CD25(+)CD4(+)Foxp3(+) regulatory T cells (Tregs) play a pivotal role in the maintenance of self-tolerance and regulation of immune responses. Previous studies have demonstrated that CD137 signals can promote proliferation and survival of Tregs in vitro. Here, we show that in vivo CD137-induced expansion of Tregs in naive mice was dependent upon IL-2 secreted by memory T cells. Tregs primed by anti-CD137 mAbs had a higher immunosuppressive capacity. Preconditioning with anti-CD137 mAbs significantly inhibited graft-versus-host disease (GVHD) in the C57BL/6 → (C57BL/6 × DBA/2) F1 acute GVHD model. In this disease model, a high proportion of host Tregs remained long-term in the recipient spleen, whereas donor hematopoietic cells replaced other host bone marrow-derived cells. Transient depletion of Tregs before transfer of donor cells completely abrogated the inhibitory effect of anti-CD137 mAbs on GVHD. In addition, adoptive transfer of anti-CD137-primed Tregs ameliorated GVHD. Our results demonstrate that it is possible to enhance the survival and/or the immunosuppressive activity of host Tregs in nonmyeloablative GVHD, and that 1 way of accomplishing this is through the prophylactic use of anti-CD137 mAbs in nonmyeloablative GVHD.

Roles of Host Nonhematopoietic Cells in Autoimmunity and Donor Cell Engraftment in Graft-versus-host Disease.

BACKGROUND: Graft-versus-host disease (GVHD) is initiated when alloreactive donor T cells are primed by host APCs to undergo clonal expansion and maturation. Since there is a controversy regarding the role of nonhematopoietic cells in GVHD, we wanted to investigate the influence of MHC disparity on nonhematopoietic cells on the pathogenesis of GVHD in the MHC-haplomismatched C57BL/6 (H-2(b)) or DBA/2 (H-2(d))-->unirradiated (C57BL/6xDBA/2) F(1)(BDF(1); H-2(b/d)) murine model of acute GVHD (aGVHD) or chronic GVHD (cGVHD). METHODS: We generated (BDF(1)-->C57BL/6), (BDF(1)-->DBA/2), and (BDF(1)-->BDF(1)) chimeras and examined GVHD-related parameters and donor cell engraftment in those chimeras. RESULTS: Using this experimental system, we found that 1) severe aGVHD across MHC Ag barrier depends on the expression of nonhematopoietically rather than hematopoietically derived alloAgs for maximal GVHD manifestations; 2) host APCs were sufficient to break B cell tolerance to self molecules in cGVHD, whereas host APCs were insufficient to induce autoimmunity in aGVHD; 3) donor cell engraftment was greatly enhanced in the host with MHC-matched nonhematopoietic cells. CONCLUSION: Taken together, our results provide an insight into how MHC disparity on GVHD target organs contribute to the pathogenesis of GVHD.