Benutzerspezifische Werkzeuge

Concept, networking and interdisciplinarity of subprojects

(I) The translational-clinical research concept and multicentre networking

Dresden represents a specialist centre with focused pockets of high technology and basic expertise combined with the necessary clinical expertise for research and care of patients with adrenal disorders. At the same time, there are significant synergistic collaborations on adrenal-related disorders with other centres within and outside Germany. Dresden participates in several networks of adrenal-related clinical research at both national and international levels, in some cases providing leadership roles. The European Network for the Study of Adrenal Tumours (ENS@T) represents one highly successful example. In one collaborative effort headed by Prof. Felix Beuschlein (Munich) that arose from this network, a European-wide multi-centre project on new therapies for adrenal cortical cancer and malignant phaeochromocytoma recently received funding under the European Union Seventh Framework Programme (FP7). As part of this effort, Dresden is the participating centre to which samples for biomarker analysis will be sent for analyses to assess therapeutic efficacy with Prof. Eisenhofer acting as the European coordinator for the associated clinical trial (FIRSTMAPPP).

Members of Dresden CRU (Bornstein, Willenberg) have also been participating in the European multicenter study on adrenal cancer (FIRM-ACT) headed by the Würzburg Centre. Furthermore, several investigators involved in the current initiative are also founding members of the Phaeochromocytoma Research Support Organization (PRESSOR at www.pressor.org), established in 2003 as part of a combined NIH and Cold Spring Harbour initiative, aimed at improved therapies for malignant chromaffin cell tumours. As part of this effort Dresden-based investigators maintain close and strong collaborations with scientists at the NIH and other participating centres belonging to this international research network. The third International Symposium on Pheochromocytoma (www.isp2011-paris.fr) is being held in Paris in the fall of 2011 as a continuation of PRESSOR-related efforts with strong involvement of investigators from Dresden.

ENS@T-based efforts related to the FP7 award and the currently proposed CRU include the setting up of a Virtual Research Environment (VRE) that covers patient registries for different adrenal tumour disease entities. These registries serve not only as repositories for comprehensive collection of patient data but also to facilitate biobanking of related human materials (i.e. tissue, plasma, urine) for subsequent studies at the bench. The registries include linked information about the type of human materials collected and available at each participating site for collaborative efforts. There is no single biobank centre. Instead materials are collected and banked at each centre according to standardised operating procedures (SOPs) and according to a unified pseudonymised coding system that adheres to regulatory requirements to facilitate exchange in collaborative efforts.

Under Prof. Eisenhofer, Dresden is leading the way in the above efforts by establishing SOPs and electronic Case Report Forms (eCRFs) for the Prospective Monoamine-Producing Tumour (PMT) study that includes centres throughout Germany and Europe. The eCRFs and biobanking efforts under that Dresden-based multicenter clinical protocol and an associated study protocol (Register und Biobank des ENS@T) provide a backbone of support for several of the CRU clinical and basic projects that require clinical data and human materials (e.g., projects 1, 2, 3, 4 and 5). Further funding support as outlined under the Z Project will allow continuation of this effort and expansion in the first instance to the diagnostic studies of aldosteronomas (Project 5) and then to other adrenal-related disorders that form the focus of the Dresden Adrenal Centre CRU. Also along this line, Dresden will participate in the National Conn Registry (www.conn-register.de) and adopt ethically approved protocols for clinical diagnostic, therapeutic and investigative procedures in the care of patients with primary aldosteronism.

In organizing the Dresden Adrenal Centre CRU, we will take advantage of the considerable expertise of Prof. Lenders, who directs the Nijmegen Adrenal Centre and is affiliated with the Department of Medicine in Dresden. Besides shared clinical protocols and exchanges of materials, we will establish educational rotations and sabbaticals of Dresden-based physicians and interventional radiologists in Nijmegen, who will transfer clinical expertise back to developing the CRU in Dresden.

Importantly, all the above mentioned networks exist on the basis of a mutual understanding of the importance of cooperative collaboration rather than divisive competition for effective and efficient advancement of medical research into adrenal-related disorders. This is particularly important for research involving rare disorders for which there is usually limited access to patient data and materials and in which multidisciplinary approaches are required that can benefit from multiple pockets of required technological, scientific and medical expertise that cannot easily all be reproduced at any one single centre. Support of the current proposal will therefore not only strengthen the national and international scientific profile of the University of Dresden, but will also serve as a model for reinforcing collaborative links to other centres and in doing so will strengthen those other centres as part of cooperative networks. Such synergistic collaboration and cooperation promise more efficient allocation and utilisation of resources in terms of both funding and accruals of patients, data and materials for high quality evidence-based medical research. A structured CRU with quality assurance procedures at suitable compliance standards also provides the necessary research culture for future industry-sponsored transfer of technology in therapeutic trials or biomarker studies in patients with hyper- or hypo-functional adrenal disorders.

(II) The translational-basic multidisciplinary research concept and local networking

The concept of the CRU involves an integrative translational research approach that considers the complete adrenal microenvironment in studies of hyper- and hypo-functional adrenal disorders. A primary clinical focus will be on phaeochromocytoma and aldosteronoma as two hyperfunctional disorders and adrenal insufficiency associated with inflammatory conditions and sepsis in the critical care setting, and the triple A syndrome in the setting of rare paediatric genetic disorders.

A hallmark of the adrenal gland is the unique co-localization of two endocrine cell systems. In addition, adrenal cells closely interact with non-endocrine cells, such as endothelial cells or inflammatory cells within the adrenal microenvironment. Both cortex and medulla are highly vascularised and rely on a complex network of neural and hormonal signals as well as on an intense crosstalk with the immune system. Intact adrenal function depends on the unification of the two endocrine tissues in a unique developmental process of tissue formation. Co-culturing of chromaffin cells with adrenocortical cells increases the production of cortisol 10-fold and activation of the splanchnic nerves stimulates both the release of adrenomedullary catecholamines and adrenocortical steroids from isolated perfused adrenals. Vice versa, glucocorticoids and adrenal androgens regulate chromaffin cell function and catecholamine synthesis.

With the above in mind it can be appreciated that dysregulation of adrenocortical steroid production will affect adrenomedullary catecholamine metabolism, which is obvious in patients with adrenocortical dysfunction such as in Addison’s disease or 21-hydroxylase deficiency. In addition, treatment of any patients for any kind of autoimmune or inflammatory disorder with glucocorticoids will reduce local adrenal glucocorticoid production within the adrenal via feedback mechanisms and therefore reduce adrenal catecholamine production. Thus, it becomes evident that only an integrative approach considering the cellular crosstalk within the adrenal microenvironment will advance our understanding of adrenal hyper- and hypofunction.

The adrenal has a unique stress response capacity. This involves hyperplasia and progressive transformation of the adrenal cortex as well as a shift in hormone production and an acute hypervascularization of cortex and medulla. A pool of adult stem cells presumably exists within this stress organ to provide the necessary plasticity for adaptation to stress. Therefore, stem cells are not only relevant for development and tumour formation but also constituting a cellular mechanism to coordinate extra-adrenal and intra-adrenal responses to stress.

Hyperplasia, transformation of the zones, and hypervascularisation are reversible adaptive processes. Metabolic syndrome and inflammatory disorders, however, lead to a chronic stress burden and aberrant stimuli on the pool of adrenal progenitor cells will possibly mediate tumour formation, hormone excess or organ failure and hormone deficiency. For the first time we have isolated and characterised sympathoadrenal chromaffin progenitor cells from the adrenal medulla. This will allow us to analyze, under controlled conditions, the effect of the important intraadrenal cellular crosstalk on adrenomedullary cell differentiation and maturation and the role of external stimuli on adrenal adaptation and maladaptation to stress as well as chromaffin tumour formation (Ehrhart-Bornstein, Androutsellis-Theotokis).

The phenotype of chromaffin cell tumours, including hormonal profiles and symptoms is closely related not only to their genotype and differentiated nature of tumour cells, but also to their locations within the adrenal or at extra-adrenal sites. Based on our microarray and proteomics data, we will analyze genotype-phenotype relationships of phaeochromocytomas, including secretory pathways relative to the tumour microenvironment as well as hypoxia-angiogenic and metabolic pathways (Eisenhofer, Lenders). Using adrenal venous sampling and histological tissue analysis of tumours from patients with aldosteronomas, we will identify new biomarkers to establish excessive aldosterone secretion and differentiate between different tumour forms (Willenberg, Eisenhofer, Lenders).

Two major previously unappreciated mechanisms for adrenal tumour development will be addressed within two other sub-projects. First, the sonic hedgehog signalling pathway that has been recently shown to regulate adrenal development will be studied in the context of steroidogenesis, adrenal tumour formation and metabolic disease (Lamounier-Zepter, Eaton). Second, in different adrenal hyperplasias and tumours such as the ACTH-independent macronodular adrenal hyperplasia, phaeochromocytoma or primary hyperaldosteronism, adrenal tumourigenesis may be triggered by the upregulation or aberrant expression of different G protein-coupled receptors (GPCR). This phenomenon may represent adaptation to chronic stress. GPCR-dependent signalling is mediated by the heterotrimeric G proteins which are likely to be involved in adrenal tumourigenesis, a hypothesis that has so far not been addressed and will be studied in detail here (Ziegler, Chavakis, Wettschureck).

In the context of adrenal hypofunction, we will focus on adrenal insufficiency associated with the triple A syndrome in the setting of rare paediatric genetic disorders and with inflammatory conditions and sepsis in the critical care setting. The triple A syndrome, an autosomal recessive disorder combining severe adrenal insufficiency with neurological impairment caused by mutations in the AAAS gene (Achalasia Addisonianism Alacrima Syndrome) has been extensively investigated in Dresden. In this syndrome, altered nucleoporins may affect oxidative stress and adrenal tissue integrity, which will be addressed with the help of genetically modified mice (Hübner).

A further major goal of this proposal is to define the role of critical components of the innate immunity for adrenal dysfunction in the course of inflammatory conditions and sepsis. This represents a continuation of our previous work (currently funded in a DFG-Normalverfahren) where we showed a tight link of the adrenal stress system to the immune system. Consistently, polymorphisms or genetic defects in elements of the innate immune system strongly affect the adrenal stress response to endotoxemia and other stressors during inflammation. Pattern recognition receptors, such as Toll-like receptors (TLR) expressed in the adrenal gland mediate the response to infection. Here, we will use mice with adrenocortical-specific or haematopoietic-specific deletion of the central signalling component MyD88 downstream of TLRs, in order to dissect in detail the contribution of TLR signalling in adrenal cells or recruited leukocytes to sepsis-related adrenal dysfunction including adrenal cell apoptosis. The latter is a crucial component of organ failure under septic conditions (Bornstein, Zacharowski).

A further crucial component of innate immunity is the leukocyte recruitment cascade. Inflammatory cell recruitment and endothelial dysfunction mediated by inflammatory pathways including TLRs may constitute a key mechanism of adrenal tissue damage during sepsis. In a complementary project (Chavakis, Bornstein), we will address how the intimate crosstalk between leukocyte-endothelial-interactions mediate endothelial dysfunction and endocrine cells may participate in adrenal hypofunction. For this, the project focuses on a novel recently described endogenous inhibitor of leukocyte-endothelial interactions, developmental endothelial locus-1. Given that the adrenal is a highly vascularised organ with the highest content of antioxidants in the human body we predict that endothelial homeostasis promotes adrenal tissue integrity, whereas endothelial dysfunction in the adrenal gland in the course of inflammatory disease may be detrimental to adrenal tissue integrity. We propose that it is imperative to understand the vascular and inflammatory components of the adrenal microenvironment as important regulators of adrenal function and dysfunction. It is evident that adrenal dysregulation including varying degrees of hypercortisolism, hyperaldosteronism and adrenal enlargement occur frequently in association with metabolic syndrome. We have previously analysed various adipocyte-derived factors (including morphogens, adipokines and other cytokines) communicating a direct signal to adrenal aldosterone and glucocorticoid production.

The unique properties of the adrenal tissue microenvironment including the dense vascularisation, make this gland an ideal organ for regenerative approaches encompassing not only the adrenals but also other endocrine organs. We therefore plan to employ our recently developed intra-adrenal transplantation and xenotransplantation models for studying adrenal regeneration. Furthermore, using the knowledge gained about the adrenal microenvironment, we will extend these studies to optimize regeneration of other endocrine organs, in particular therapeutic pancreatic islet transplantation (Ludwig, Morawietz, Bornstein).

We have gathered a series of genetically modified mouse models, such as transgenic Cre lines that together provide an unprecedented collection of tools allowing for adrenocortical cell-specific deletion (Akr1b7-Cre), sympathoadrenal cell-specific deletion (tyrosine-hydroxylase-Cre), adipocyte-specific deletion (FABP4-Cre), endothelial cell-specific deletion (VE-cadherin-Cre, SCL-Cre-ERT2), and haematopoietic-specific deletion (Mx1-Cre) of important factors in mice with conditional alleles (e.g. mice with floxed alleles of Myd88, HIF-2alpha, PHD3, different G proteins). These tools allow for a thorough assessment of each single component of the adrenal microenvironment in a model system. In addition, we have important reporter mouse models (e.g. Nestin-GFP mice or reporter mice for the sonic hedgehog signalling pathway).

In a similar fashion to the central administration of patient-oriented research studies by Prof. Eisenhofer, the mouse models will be centrally administered by Prof. Chavakis (Fig. 2). This will allow for an efficient management of the resources available to all groups. Together, this unique collection of mouse models will allow a thorough and innovative analysis of molecular interactions and of the cellular crosstalk within the adrenal microenvironment. They also allow for a translational preclinical approach to assess the role of adrenal hyper- and hypofunction in adrenal disorders and other stress-related chronic diseases. Combined with the infrastructure for clinical studies, these mouse models provide an essential resource to complete the final half of bedside-to-bench-to-bedside cycle of translational research that we perceive will develop from the basic and clinical projects outlined here.

Introduction fig 2
Figure:The concept and networking of the Clinical Research Unit on the microenvironment of the adrenal.


The research unit has the joint framework focus on the adrenal gland microenvironment with a comprehensive view on the cortical and medullary adrenal endocrine systems and their crosstalk with endothelial cells and inflammatory pathways. The centre has the unique strengths of bringing together the expertise of researchers in both chromaffin and steroid cell biology in close collaboration with researchers from other disciplines, such as clinical chemistry, immunology, vascular biology and pharmacology. The involvement of such disciplines is indispensable in view of the complexity of the cellular interactions the elucidation of which can benefit from a modern systems biology approach.

With the above critical structures in place, access of basic investigators to clinical data and materials will be facilitated and work on model systems, such as those involving new technologies to assess or treat adrenal related disorders, will be more readily translated into clinical practice. Vice versa, clinical investigators will more readily have the means to utilise bench level expertise and technologies to carry out high-quality patient-oriented research. Such intensified cooperative efforts between basic and clinical investigators utilising a bidirectional bench-to-bedside-to-bench approach can be expected to considerably improve the resulting research product.

In conclusion, a comprehensive analysis of adrenal regulation and dysregulation is overdue and now of strategic clinical relevance. The clinical research group will be able to define the mechanisms of adrenal impairment and separate beneficial adaptation to environmental challenges from true deficiencies. This will enable us to implement correct interpretation of data and consequently develop better diagnostic tools and improved strategies for medical management and treatment of adrenal-related disorders. This will also help to identify the true risk groups for adrenal diseases, adrenal hypo-and hyperfunction and raise awareness for these frequently underdiagnosed or misdiagnosed clinical problems.