In 2007, seven projects were awarded through the HAA’s Research Program.
The first five were funded by the Histiocytosis Association of America.
Project Title
Ganglioside-Induced Defective Granule Exocytosis-Mediated Cytotoxicity in
Hemophagocytic Lymphohistiocytosis
Principal Investigator
Sasa Radoja, PhD
Children's National Medical Center – Washington DC, USA
Date of Award
December 2007
Amount of Award
$50,000
Layperson Summary
Hemophagocytic lymphohistiocytosis (HLH) is a life threatening immune disorder that usually presents during infancy or early childhood. Dysfunction of a particular type of immune cells, called “killer cells” is thought to be the basis for development of HLH. The levels of a factor, a type of lipid called ganglioside, are known to be elevated in blood of HLH patents. Previous studies have suggested that the increased levels of this lipid factor cause dysfunction of the killer cells, which in turn contributes to the development of HLH disease. The goal of our studies proposed here is to determine exactly how this lipid factor depresses the function of the killer cells. We believe that findings originating from the studies will allow us to better understand how this disease develops and eventually help us find more efficient ways for its treatment.
Project Title
Lymphocyte Trafficking in Langerhans Cell Histiocytosis
Principal Investigators
Carl Allen, MD, PhD and Kenneth McClain, MD, PhD
Texas Children’s Cancer Center/Hematology Service - Houston, Texas USA
Date of Award
December 2007
Amount of Award
$50,000
Layperson Summary
Langerhans Cell Histiocytosis is a potentially fatal disease thought to be caused by uncontrolled proliferation of Langerhans cells. Typically, Langerhans cells are located in the skin. The job of these cells is to recognize signals from the environment and to activate the immune system to respond to “danger” signals. When the Langerhans cell is activated it migrates to lymph nodes where it communicates with T cells. The T cells then become activated and create an inflammatory response that fights cells with “foreign” material such as viral proteins. Currently there is debate among researchers whether proliferating Langerhans cells arise due to changes in the cell similar to a cancer cell, or whether these cells become activated and divide due to pro-inflammatory signals from the immune system. Preliminary studies in our lab suggest that neither of these models may be accurate. Based on analysis of gene expression in Langerhans cells isolated from LCH lesions, these cells are not proliferating more rapidly than control skin Langerhans cells, nor are they producing pro-inflammatory cytokines at a level higher than control skin Langerhans cells.
We hypothesize that Langerhans cells and other lymphocytes accumulate in skin, bone and other areas due to inappropriate cell trafficking and that accumulation of these cells in lesions gives rise to LCH tumors. We propose to test this theory by validating our preliminary gene expression studies and by testing new tumor samples we collect over the next year. We also propose testing gene expression in cells in blood that give rise to Langerhans cells and Langerhans cells from LCH patients to identify genes that may be involved in inappropriate cell migration. Finally, we propose to re-visit the idea that Langerhans cells in LCH lesions are clonal, meaning that all of the Langerhans cells in a lesion arise from a single progenitor cell. If LCH arises from abnormal cell migration, we expect the accumulation of Langerhans cells in a lesion to arise from many progenitor cells. If LCH does in fact occur because of abnormalities of cell migration rather than from cell proliferation, we may be able to design more effective treatment strategies that target mechanisms involved in regulation of cell trafficking.
Project Title
Investigations into the Clinical and Molecular Mathogenesis of XIAP Deficiency
Principal Investigators
Rebecca Marsh MD; Jack J. H. Bleesing MD, PhD; Kimberly Risma MD, PhD;
Lisa Filipovich MD
Cincinnati Children's Hospital – Cincinnati, Ohio USA
Date of Award
December 2007
Amount of Award
$50,000
Layperson Summary
Primary Hemophagocytic Lymphohistiocytosis (HLH) is a rare, life-threatening disease typically caused by defects in the ability of killer lymphocytes to effectively clear viral infection. There is essentially overactivation of the faulty immune system which then leads to systemic inflammation and multi-organ failure if left untreated. There are several known genetic defects which lead to HLH, though the underlying genetic cause of HLH in many patients remains unknown. Recently, a newly identified X-linked genetic defect has been reported to be the cause of of HLH in three families, with 11/12 of these patients developing HLH, 4 of whom died. The defect is in the gene encoding the X-Linked Inhibitor of Apoptosis, or XIAP. XIAP is known to inhibit cell death by interacting with several proteins which are involved in apoptotic cell death, and also has lesser understood roles in certain cell signaling pathways. It is unclear why a deficiency of XIAP leads to HLH.
We have recently diagnosed XIAP deficiency in 5 patients from 4 families with variable manifestations of primary immune deficiency, evidence of immune dysfunction/dysregulation, and propensity to develop HLH. The work we propose involves three major areas of research related to the understanding of this new disease. The first area is the detailed characterization of affected patients. Features of interest include patient lymphocyte populations and specialized characterization of those cells, along with monitoring of their function over time. Monitoring of HLH-specific markers at baseline and with relapse and remission will also be performed. We also have begun work to develop a screening diagnostic test. The second area is the determination of both intact and compromised XIAP protein sequences expressed by our XIAP deficient patients and correlation with functional assays relevant to XIAP function. Third, we will further investigate the reason for the development of HLH in XIAP deficient patients, including analysis of the function of cytotoxic cells, which is a well-described mechanism of HLH development in many of the other causes of primary HLH.
Project Title
A Transgenic Mouse Model Mimicking Abnormal Langerhans Cell Trafficking
in Langerhans Cell Histiocytosis
Principal Investigators
Barbara Brandner, PhD and Barrett J. Rollins, MD, PhD
Dana-Farber Cancer Institute, Harvard Medical School
Boston, Massachusetts USA
Date of Award
December 2007
Amount of Award
$50,000
Layperson Summary
Langerhans cell histiocytosis (LCH) is a rare disease that mainly affects children. Cells of the immune system, called Langerhans cells (LCs), accumulate in various organs and cause damage, in severe cases even leading to death. The cause of this disease and the factors leading to its progression are still unknown.
Chemokine receptors act as signposts on cells of the immune system. In healthy people the chemokine receptor CCR6 is involved in retaining resting LCs in the skin while the chemokine receptor CCR7 directs mature LCs to the lymph nodes, but they never appear at the same time on the same cells. However, in LCH both of these receptors are present on abnormal LCs. The simultaneous appearance of these receptors is probably not the cause for the disease, but could be responsible for the misguided accumulation of LCH cells in different organs. We want to test the importance of this finding in mice by genetically modifying their LCs to display these two chemokine receptors simultaneously. We will examine the journey of these cells in the genetically modified mice and we will compare it to mice that do not display these receptors on their LCs. We will examine organs in these mice such as skin, lymph nodes, spleen, liver, brain and bone for the presence of LCs and other cells that are found in human patients suffering from LCH and contribute to the organ damage. In addition, we will investigate the migration of LCs after mild inflammatory skin challenge and we also will study the isolated LCs outside of the mouse.
Our mouse model of abnormal LC migration will help us understand the progression of LCH and other histiocytic disorders and give insight into disease mechanisms. Many pharmaceutical companies are developing drugs that block chemokine receptors. If our work shows that these receptors contribute to the manifestations of LCH, then we can plan to test the effects of chemokine receptor blockers in patients with the disease.
Project Title
Role of the Granzyme Inhibitor Proteinase Inhibitor-9 (PI-9) in
Langerhans Cell Histiocytosis
Principal Investigator
Carl Friedrich Classen, MD
University Childrens Hospital Rostock - Duisburg, Germany
Date of Award
December 2007
Amount of Award
$25,000
Layperson Summary
Langerhans cell histiocytosis (LCH) is a disease characterized by irregular proliferation of Langerhans cells - a subgroup of dendritic cells (DC) - with a broad spectrum of clinical manifestations, ranging from small solitary bone lesions to multi-organ diseases which may be fatal despite extensive therapeutical efforts. The mechanisms by which the disease develops, however, is largely unknown.
In several malignant diseases, especially lymphomas, it has been found that expression of a protein called Proteinase inhibitor 9 (PI-9) is correlated to a bad prognosis. PI-9, which is highly expressed in normal Langerhans cells, is the only known endogenous antagonist of the protein granyzme B (GrB). GrB is a cytotoxic protease, by which cytotoxic T lymphocytes (CTL) kill their targets, like malignant or virus-infected cells.
The normal function of Langerhans cells and other DC is antigen presentation to T-lymphocytes, leading to activation of specific immune responses. In this context, PI-9 protects cells - both the cytotoxic lymphocytes themselves and the antigen-presenting cells - from misdirected GrB. Thus, it is involved in normal immune regulation. However, it is completely unknown whether PI-9 is also expressed in LCH, and whether it may contribute to the disease course, e.g. by conferring resistance towards cytotoxic T lymphocytes.
In the present work, we want to analyse PI-9 expression retrospectively in specimens of LCH patients with different clinical course. Further, regulation of PI-9 upon in-vitro stimulation will be studied in normal Langerhans cells, Langerhans cells induced in vitro, and fresh tumor cells from LCH patients.
The aim is first to define a possible relationship between PI-9 expression and LCH subtype, second to identify the role of PI-9 in the development and prognosis of LCH, and finally to find out whether this might represent an aim for new, targeted therapy modalities.
The following two projects were funded by the Histiocytosis Association of Canada.
Project Title
Biomarker Monitoring of Central Nervous System Disease in
Langerhans Cell Histiocytosis
Principal Investigator
Jan-Inge Henter, MD, PhD
Karolinska Institutet – Stockholm, Sweden
Date of Award
December 2007
Amount of Award
$50,000
Layperson Summary
Problem formulation: Langerhans cell histiocytosis (LCH) is a disease of unknown cause and a remarkably variable clinical course. It may present as a discrete or intense rash, or as one or multiple lytic bone lesions that may resolve spontaneously, but it may also develop into a potentially lethal disease involving specific risk organs, defined as the lungs, liver, spleen and the hematopoietic system.
During recent years it has become obvious that the risk of developing late sequelae is one main concern in LCH, and it may affect as many as 40-60% of all survivors. One major concern is the risk of developing progressive degeneration of the brain, often referred to as Central Nervous System-LCH (CNS-LCH). The CNS may be affected already at the diagnosis of LCH, then most commonly involving the hormonal function that may result in diabetes insipidus, growth hormone deficiency and sometimes also more extended hormone deficiencies.
Of particular concern is the development of cerebral dysfunctions, and clinical CNS complications has been reported to affect at least 10% of all LCH patients. Notably, these CNS complications can be both pronounced and severe, and result in severe neuromotor deficiencies, behavioral disturbances, as well as severe cognitive dysfunctions and death. It is also alarming that this neurodegeneration appear to be progressive, and neurological sequelae may appear as late as 20 years after the initial diagnosis. Imaging with Magnetic Resonance Imaging (MRI) is today considered the best way to diagnose neurodegeneration in LCH.
Obviously, there is a desire to reduce the clinical development of CNS-LCH. However, in order to evaluate potential therapies there is a need to be able to monitor the disease course in the CNS, and since the clinical deterioration and the development of radiological findings are slow processes, it is presently difficult to evaluate the effects of various therapeutic attempts. Therefore, it would be beneficial to be able to evaluate present, ongoing CNS disease activity.
Specific Aim: To identify and evaluate biomarkers of present, ongoing CNS-LCH activity.
Work proposed: In a cohort of patients with MRI-verified CNS-LCH, we perform lumbar puncture (a clinical routine procedure) in order to obtain cerebrospinal fluid (CSF) samples. We analyze these CSF samples to evaluate the potential value of CSF biomarkers used to evaluate other neurodegenerative disorders. These markers are called glial fibrillary acid protein (GFAp), neurofilament protein, light chain (NF-L), and total tau protein. We then aim to correlate these CSF biomarker levels with clinical and neuroradiological findings.
Preliminary data: We have evaluated NF-L, tau and GFAp levels in a set of CNS-LCH patients and noticed that all these children had elevated levels of at least one of these markers. Notably, the patient with the most severe clinical and neuroradiological CNS-LCH also displayed the highest levels of NF-L and GFAp. Similarly, three patients with non-active disease at the time of evaluation had low tau levels and normal or only slightly elevated NF-L. Moreover, the tau levels also correlated with the systemic disease activity.
Project Title
Mechanisms of IL-17A-Dependent Dendritic Cell Long-term Survival and Fusion
in Langerhans Cell Histiocytosis
Principal Investigator
Christine Delprat, MD, PhD
INSERM – Lyon, France
Date of Award
December 2007
Amount of Award
$50,000
Layperson Summary
Langerhans cell histiocytosis (LCH) may affect any age group, from the newborn to the elderly, but clinical features, pathogenesis, and treatment outcome derives from the pediatric experience. The incidence for LCH of around 1:200,000 children per year, peaks at 1–3 years.
LCH is an ‘orphan’ disease that belongs to the Histiocytoses. The course of LCH is often unpredictable, varying from spontaneous regression and resolution to rapid progression and death or repeated recurrence and recrudescence with a considerable risk of permanent sequelae since tumors destroy the tissue where they grow: bone in 80% of patients with multisystem disease, but also soft tissues and occasionally central nervous system involvement.
We have just demonstrated that inside lesions, dendritic cells (DC) and multinucleated giant cells (MGC) produce IL-17A, a messenger of the human immune system which has a dominant role in the development and maintenance of several chronic inflammations, such as Mycobacterium infection, Crohn's disease, rheumatoid arthritis and multiple sclerosis. Thus, LCH belongs to IL-17A-related disease family. Moreover, we have just discovered a novel IL-17A-dependent pathway of DC fusion which probably gives rise to MGC observed in LCH lesions.
Our objective is to discover the mechanisms of DC long-term survival induced by IL-17A and required for DC fusion in order to design therapeutic agents able to prevent DC survival and their subsequent fusion and differentiation into aggressive tissue-destructive MGC. These therapeutic agents may abrogate or at least reduce tissue destruction in all LCH lesions.
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