2007 Grant Recipients Talk about their Research
Abstract title: A New Prognostic Factor and Potential Treatment of Chronic Lymphocytic Leukemia (CLL)
BD: You mentioned that you came from a family of scientists?
Olga Danilova: Yes. I’m from Russia. My father taught social forensic medicine, so as a child I was exposed to what looked to me like interesting charts and graphs and statistics of various kinds. I always thought I wanted to do the same thing. Eventually I went to medical school and then received my PhD.
BD: You are working on chronic lymphocytic leukemia (CLL) now?
Olga Danilova: Yes, and we believe we may have an idea for a new, inexpensive prognostic kit that can help select CLL patients most suited to a treatment based on inducing apoptosis by inhibiting a serine protease, dipeptidyl peptidase 2 (DPP2). Our proposed test for susceptibility to DPP2 inhibition-induced apoptosis would be a prognostic test that can replace the cumbersome and expensive analysis for BCR heavy chain immunoglobulin (IgVH) mutational status, which is the current gold standard.
BD: How does this work?
Olga Danilova: CLL is characterized by the accumulation of quiescent B-lymphocytes in the peripheral blood. In this quiescent state (also called the G0 phase), the cell is not dividing. One approach to treatment is to induce apoptosis to these cells. Using the BD Annexin V APC staining intensity to detect apoptosis, we studied 60 CLL patients and were able to separate them into two groups: those that are sensitive to apoptosis induction (the S-CLL group) and those that are resistant to induction (the R-CLL group). Compared to the S-CLL group, R-CLL patients were associated with a less favorite course of the disease, carried the unmutated IgVH gene and expressed ZAP-70 protein, which can be detected using the BD ZAP-70 intracellular staining kit.
BD: What will you do with the grant from BD Biosciences?
Olga Danilova: First, we want to confirm our findings with a larger group of 200 patients, and see if we are in the right direction for an inexpensive prognostic kit for CLL. Next, we want to understand the underlying molecular mechanism that causes the two patient subsets to respond differently to DPP2-induced apoptosis. And this work can lead to the design of new treatment strategies for the more aggressive CLL subset with the worse prognosis.
Abstract title: Identification of Osteoclast Progenitor Cells
BD: How did you become interested in bone research?
Yihong Wan: I’ve always been interested in nuclear receptors and how they act as genetic switches by regulating transcription. As a doctoral student, I worked on the glucocorticoid receptor and the progesterone receptor, within the broader framework of understanding the interrelationship between nuclear receptors and physiological processes. My current research focuses on the peroxisome proliferators-activated-receptor-gamma (PPAR-gamma), with particular emphasis on its role in bone metabolism. Osteoporosis afflicts ten million Americans today, and it is particularly gratifying to know that my work can help understand this debilitating disease and identify paths toward prevention and cure.
BD: Let’s talk about your grant proposal. Why focus on osteoclast progenitor cells?
Yihong Wan: Bone is a dynamic tissue that undergoes constant remodeling through balancing bone formation by osteoblasts and bone resorption by osteoclasts. Osteoblasts are of mesenchymal origin, while osteoclasts are of hematopoietic lineages. Our recent study uncovered a pro-osteoclastogenic effect of the nuclear receptor PPAR-gamma. When PPAR-gamma is deleted in hematopoietic but not mesenchymal lineages, the mice develop osteopetrosis, exhibiting defects associated with impaired osteoclast differentiation and that can be rescued by bone marrow transplantation.
Our study aims to identify and characterize osteoclast progenitor cells using the comprehensive array of mouse cell surface molecules, flow cytometry instruments, stem cell reagents, and CBA bead-based immunoassays from BD Biosciences, in combination with PPAR-gamma agonist and PPAR-gamma conditional knockout mice.
BD: What are the goals of this research?
Yihong Wan: The goal of our study is two-fold: to identify the osteoclast progenitor cell population in the bone marrow and then to determine the molecular signature of these osteoclast progenitor cells. Ultimately, our work will lead to a better understanding of osteoclast regulation and bone remodeling; and this understanding will lead to better treatment of metabolic and inflammatory bone disorders.
BD: Isn’t PPAR-gamma also implicated in fractures associated with certain diabetes treatments?
Yihong Wan: Indeed. The implied role of PPAR-gamma as a robust stimulator of osteoclastogenesis is of clinical significance in light of the increased rate of fractures reported in diabetic patients treated with the PPAR-gamma agonist rosiglitazone in the recent A Diabetes Outcome Progression (ADOPT) trial. By elucidating the role of PPAR-gamma in bone metabolism, our research may point the way to better drugs for diabetes
Abstract title: The Role of Plasmacytoid Dendritic Cells and Immune Tolerance in Cancer
BD: You’ve spanned quite a number of scientific disciplines in your studies, haven’t you?
Duane Jeansonne: As an undergraduate, I majored in microbiology with a minor in chemistry at Louisiana State University. During my graduate work at Tulane University Health Sciences Center, I studied the effect of the inhibitor PP1 on peptide phosphorylation by the kinase c-Src. My work today is certainly more related to cell biology, but our lab as a whole covers everything from biochemistry to immunology.
BD: Tell us about your work.
Duane Jeansonne: I’m interested in understanding how tumors actively prevent induction of tumor-associated antigens (TAA) and thus block the spontaneous clearance of tumors by the immune system. Studies have shown tumors are able to prevent TAA presentation, and the thinking was that either tumors do not present enough TAA or the antigen-presenting cells do not have sufficient capacity to stimulate an immune response. However, it is now known that tumors actively prevent induction of TAA-specific immunity through induction of TAA-specific tolerance.
BD: So tumor immunity can be a path toward novel therapeutic strategies then?
Duane Jeansonne: To understand the complex responses, we are studying human plasmacytoid dentritic cells (PDCs), which have been shown to mediate antigen-specific immune tolerance and have been reported to induce CD4+CD25+ regulatory T cell (Treg) differentiation. CD4+CD25+ Tregs are elevated in human cancers, and our lab recently showed that these cells inhibit TAA specific immunity and predict poor survival in human ovarian cancer. Our hypothesis is that tumor PDC-induced Tregs inhibit TAA-specific immunity and facilitate tumor growth. So, understanding these processes is central to unraveling the immunopathologic basis of cancer. This research project will test the hypothesis that Tregs activated by tumor PDCs block TAA-specific immunity. Using mouse models we hope to demonstrate that PDC-activated Tregs
This research project will test the hypothesis that Tregs activated by tumor PDCs block TAA-specific immunity. Using mouse models we hope to demonstrate that PDC-activated Tregs can inhibit TAA-specific immunity in vivo and block immunologic tumor rejection.
Most importantly, if we are able to block these tolerizing conditions, we’ll have a novel therapeutic strategy against ovarian cancer and other malignancies.
Abstract title: B cell Alternative Receptors
BD: Can you tell us how your interest in human schistosomiasis evolved?
Lisa Ganley-Leal: I received my PhD in immunoparasitology from the University of Connecticut Health Center. In graduate school, I spent two years on wildlife diseases. I worked with all kinds of animals — skunks, opossums — and they all had parasites in them. I was intrigued. Does this have to do with homeostasis? Does every animal need worms?
BD: So this interest in animals led you to Africa?
Lisa Ganley-Leal: Well, my first post-doctoral fellowship was with the Centers for Disease Control and Prevention (CDC) and this took me to Kenya. I worked on the role of eosinophils in host protection. We studied male Kenyan car washers working in the area of Lake Victoria. These car washers are exposed to Schistosoma mansoni cercariae. Cercariae are the larval worms of the schistosomes, transmitted by snails living in the water. The car washers stand in the water all day long. The infected workers are treated with Praziquantel (Biltricide), and then they go back to work and became exposed again. Eventually, we learned that high serum concentrations of parasite-specific IgE are correlated to resistance to reinfection, but we were not sure how the IgE works.
BD: How did this lead to Boston University and your research today?
Lisa Ganley-Leal: Well, at the end of my first post-doc term, I gave birth to twins. I returned to work and connected with a lab here that was working on human B cells. My mentor at the time directed me toward alternative receptor use by human B cells. Now, IgE is produced by B cells, but we know little about B cell function and the mechanisms involved in the maintenance of elevated serum IgE in schistomiasis. So my work continues on how B cells and IgE help protect against schistosome infection, as does the collaboration with the CDC and the Kenyan Medical Research Institute.
BD: What is the current direction of this research?
Lisa Ganley-Leal: We are focusing on IL-4. Because the intrinsic ability to secrete higher levels of IL-4 is also associated with resistance to schistosomiasis, we hypothesized that IL-4 might alter the ability of the B cell to recognize antigens. We hope that a better understanding of how human B cells recognize and process schistosomal antigens will lead to better strategies for vaccination.
Abstract title: Latexin: A New Tumor Suppressor
BD: Were you trained as a doctor? And how did you transition from medicine to research?
Ying Liang: I received my medical degree in China. After completing my residency, I realized that I am more interested in research, and I came to the University of Kentucky, where I received my PhD.
BD: Tell us about your work on the Latexin (Lxn) gene.
Ying Liang: Recently, our lab discovered the novel roles of Latexin (Lxn) gene and its protein product Laxetin in mice. This gene is involved in the regulation of proliferation, apoptosis, self-renewal, and subsequently pool size, of normal hematopoietic stem cells. Previous studies showed that Lxn is highly homologous to Tazarotene-Induced Gene 1 (TIG1), which is down-regulated or absent in many tumor types. So our hypothesis is that Lxn is a potential tumor suppressor and plays a role in hematologic malignancies.
BD: How will you go about testing your hypothesis?
Ying Liang: First, we need to determine if Lxn expression is altered in leukemic cells. Our initial studies had shown that Lxn expression is either absent or reduced in acute myeloid leukemia (AML) cells from three patients and in leukemia cell lines. We need to expand this study to other types of myeloid and lymphoid leukemia samples. We also plan to use different combination of cell surface markers to look at Lxn expression at different stages of leukemia development.
Next, we want to investigate the underlying mechanisms for the down-regulation or absence of Lxn expression in leukemia cells. Promoter methylation has emerged as a novel mechanism for inactivating tumor suppressor genes. Our preliminary experiments support the notion that promoter hypermethylation is a key mechanism suppressing Lxn expression. Now we need to look at purified leukemia stem cells (LSCs) or progenitor cells.
The third question is whether expression of constitutively active Lxn in leukemia cells will inhibit tumor growth by decreasing cell proliferation and/or increasing apoptosis. We will construct a retroviral vector containing Lxn, over-express Lxn in leukemia cells, and study the growth characteristics of the cells infected with either the Lxn or empty vector. We will rely on BD Biosciences products to determine population doubling times, identify the fraction of cells in G1, S, and G2/M phases of the cell cycle, and measure the fraction of apoptosis cells.