1st International Meeting on Neurobiology of the Skin
Mövenpick Hotel, Münster. Germany
February 13-15, 2004.

1. Name, address, Tel. No., Fax No, E-mail code of the applicant(s)
Markus Böhm, MD (bohmm@uni-muenster.de)
Thomas E. Scholzen, PhD (thoscho@uni-muenster.de)
Martin Steinhoff, MD, PhD (msteinho@mednet.uni-muenster.de)
Contact Address: Congress Bureau "Neurobiology of the Skin"
Congress Secretaries: Mrs. Sabine Grünig, Mrs. Marie-Luise
Hülmann and Mrs. Simone Bröker
University of Münster, Department of Dermatology
Von-Esmarch-Strasse 58
48149 Münster, Germany
Phone: + 49 251 83 56504
Fax: + 49 251 83 56522

2. Name of body organizing the meeting, names of the organizing Committee
Organizing body: University of Münster, Department of Dermatology
Organizers: M. Böhm
T.E. Scholzen
M. Steinhoff
Local Organizers: Department of Dermatology
Prof. Thomas A. Luger, MD (Chairman of the Department)
Sonja Ständer, MD
Meinhard Schiller, MD
Thomas Brzoska, PhD

3. Place and date of the meeting
Mövenpick Hotel, Münster
Kardinal von Galen Ring
48149 Münster, Germany
February 13 - 15, 2004

4. Title: 1st International Meeting on Neurobiology of the Skin

5. Scientific summary of the conference
In the skin, various diseases such as atopic dermatitis, urticaria, psoriasis, diseases of the pilosebaceous unit, the growth of skin tumors, but also physiological processes (pigmentation, hair growth, angiogenesis or wound healing a.o.) have been demonstrated to be associated or affected by neuromediators. Most of the above diseases are frequent in our society with a high socio-economic factor. During the last few years, a modern concept of an interactive and interdependent network between the cutaneous neurological system, the neuroendocrine axis and the immune system has been established. Data available at present very clearly indicate that neuromediators influence a variety of physiological and pathophysiological functions including cellular development, growth, differentiation, immunity, inflammation, pigmentation, vascular biology and wound healing.
The interaction between the nervous system and the immune system is mediated by cutaneous sensory nerve fibers, which release neuromediators capable of activating specific receptors on target cells in the skin. The first session of the meeting, Drs Sternini (S01) and Handwerker (S02) provided the participants with an overwiew of the anatomical basis for the interaction of nerves with skin cell including keratinocytes, mast cells, Langerhans cells, microvascular endothelial cells, fibroblasts, sebocytes and immune cells infiltrating into the skin. The close anatomical relation of sensory and autonomous nerves with skin and immune cells is not only the provision for maintenance of skin homeostasis, but also for the transmission of hyperalgesia and hyperknesis in dermatological disease. In addition as pointed out by Dr. Rameshwar (S03), innervated structures in the bone marrow form synapse-like structures with mesenchymal cells. This appears to be relevant for hematopoiesis since these cells generate stromal cells that support hematopoiesis, and control trafficking of cells in an out of the bone-marrow as well as its inflammation. In this system, tachykinins via neurokinin receptors are involved in regulation of vascular/barrier functions and immune responses of the bone marrow.
The second session focused on the role of skin derived neuroendocrine hormones particularly proopiomelanocortin peptides and their corresponding receptors, which are produced locally by epidermal and dermal skin cells. Classically, POMC processing in human melanocytes has been widely documented and the a-melanocyte-stimulating hormone (a-MSH)/melanocortin 1 receptor (MC-1R)/cAMP cascade have been implicated in the control of pigmentation. Novel insight into the regulation of MC-1R signaling was provided by Busca and Garcia-Borron et al. demonstrating that signaling of the MC-1R not solely involves elevated cAMP and protein kinase A activation. Likewise, by inhibiting other pathways such as IP3 MC-1R signaling contributes to activation of transcription factors such as MITF and CREB that are responsible for regulation of melanogenesis, melanosome transport and potentially melanocyte differentiation. In addition, G-protein coupled receptor serine/threonine kinases (GRK2 and GRK6) impair MC-1R signalling which strongly implies that these kinases are key regulators of MC-1R and important determinants in normal and pathologically altered skin pigmentation. Biochemical and biologic studies presented by Dr. Barsh supported that melanocyte function and pigmentation is further influenced by accessory proteins such as agouti, attractin and mahogunin. These proteins are important determinants in pigment type-switching from eumelanin to pheomelanin during hair growths by modulating MC-1R signaling. In contrast, a number of allelic variants of the MC-1R result in a disturbed function of this receptor altering the pigmentation phenotype in men by changing the relative amounts of eumelanin and pheomelanin. This is of particular importance since loss-of function mutations of the MC-1R have not only been associated with fair skin, but also with an increased risk of skin cancer and particularly the development of melanoma (S07). On the other hand, Schallreuther (S04) provided novel evidence that pigmentation could potentially be induced by MC-1R independent mechanisms due to intracellular binding of melanocortins (a-MSH or ß-MSH) to cofactors such as 6-tetrahydrobiopterin, that are essentially involved in the biochemical generation of melanin.
Neuropeptides, neuroendocrine hormones and neurotrophins serve to regulate skin homeostasis, inflammation, immune responses and tissue repair and in part constitute an intrinsic cutaneous hypothalamus-pituitary-adrenal axis that is capable of mounting an effective skin stress response (S16, A. Slominski). This latter is accomplished by expressing corticotropin releasing hormone and related urocortin peptides, POMC peptides and their corresponding receptors as well as enzymes of the corticosteroidogenic pathways. This cutaneous CRH/POMC system appears to be highly responsive to the common stressor ultraviolet irradiation, cutaneous pathology or physiologic changes associated with the hair cycle. Thus, there is no doubt that a multidirectional communication between the peripheral nervous system and the immune system in the skin exists. This was impressively demonstrated by Drs. R. Paus (S09) and D. Tobin (S10) showing that the hair follicle offers a highly instructive and clinically most relevant research model for dissecting, how sensory nerves, central and peripheral endocrine loops and the immune system interact in order to adapt skin functions to changing environmetal conditions.
Likewise (S11, C. Zouboulis), proposed that other skin adnexal structures such as the sebaceous gland are equally important parts of a hypothalamus-pituitary-skin axis and sensory neuropeptides such as substance P are capable of regulating sebocyte functions including the synthesis of lipids.
From a functional aspect, one of the most important features of the skin immune system is its capability of responding to exogenous or endogenous stressors including ultraviolet irradiation, bacterial infection, heat, chemicals, allergens or mechanical trauma. Usually, the innate immune system generates an inflammatory response that tries to neutralize the stressor, and in parallel activates an adaptive immune response. Such responses are frequently initiated by direct activation of ion channels that belong to the transient receptor potential vanilloid type 1 (TRPV1) family. These receptors are expressed by sensory neurons and function as "stress sensor" as they are directly activated by noxious agents such as heat, ethanol, low pH or neurotoxic agents such as vanilloids including capsaicin. As pointed out by P. Geppetti (S17), activation of these receptors on sensory neurons triggers the release of neuropeptides including substance P or calcitonin generelated peptides that are important mediators of neurogenic inflammatory responses and thus contribute to or worsen skin inflammation, asthma or ethanol-induced migraine. Another important mechanism of sensory nerve activation relevant for cutaneous inflammation was summarized by M. Steinhoff (S18). Proteinase-activated receptors (PARs) are G-protein coupled-seven transmembrane receptors that can be activated by serin proteases such as thrombin, trypsin or tryptase. Proteolytic activation these receptors that are expressed on sensory neurons results in the release of neuropeptides and the onset of neurogenic inflammation (edema, plasma extravasation and neutrophil recruitment). In addition, PAR expression and activation on epidermal and dermal cells directly activates NF-?B, an important transcription factor involved in inflammatory and immune responses and subsequently induces cytokines and adhesion molecules controlled by NF-?B. Thus, it was proposed that PAR-modulating agents may be new tools for the treatment of skin disease and inflammation.
Neuropeptide effects are usually mediated by highly specific G-protein-coupled receptors. This is not only true for MC-R as outlined above, but also for tachykinin (neurokinin; NK) receptors and receptors for calcitonin gene-related peptide and adrenomedullin. Cellular responses to agonists of G-protein coupled receptors depend in large part on the trafficking of receptors between plasma membrane and intracellular locations. In the paper presented by N.W. Bunnett (S19), the importance of ß-arrestins and of the nature of the stimulus for desensitization/resensitization, respectively, of NK-R was discussed. Accordingly, short time stimulation of NK-1R by nanomolar concentrations of SP result in receptor recycling, whereas high concentration of SP and prolonged incubation with the ligand leads to NK-1R ubiquitation and degradation. For CGRP and adrenomedullin (AM), another novel and so far unique concept of receptor regulation was elucidated by Fischer et al. (S31). CGRP and AM, potent vasodilators, activate a calcitonin receptor-like receptor (CRL). The coexpression and heterodimeric non-covalent interaction of receptor activity modifying proteins (RAMP) and the CRL determines the pharmacological properties of the CRL. CRL/RAMP1 defines a CGRP receptor, whereas RAMP2 and -3 correspond to AM1 and AM2 receptors, respectively. The AM1 receptors crossreacts with CGRP at high, and the AM2 receptor at low concentration. S.D. Brain (S28) provided insight into the importance of both NK-1R and CGRP/AM receptors and their ligands SP and CGRP for skin neurogenic inflammatory responses. Mice lacking NK-1R or a-CGRP mounted an impaired oedema formation in neurogenic inflammatory responses triggered by TRPV1 activation. Only simultaneous blocking of SP/CGRP activated pathways inhibited both oedema formation and vasodilator responses indicating redundancy in the terms of dilator mechanisms. Importantly, novel data suggest that in addition to CGRP, skin cell-derived AM can act as a non-neuronal-derived CGRP agonist in the skin thus contributing to vasodilatation and cell accumulation. Interestingly, there is also evidence for a crosstalk between CGRP and NK-1R that requires further clarification.
From these and previous studies a concept of SP as proinflammatory mediator in cutaneous inflammation has emerged. This was supported by J.C. Ansel (S29) and P. Baluk (S30) indicating the importance of SP/NK-1R for inflammatory activities of dermal vascular endothelial cells and neurogenic inflammation of the airways. For example, SP via NK-1R is capable of directly upregulating the expression of endothelial cell adhesion molecules responsible for recruiting leukocytes to the site of inflammation. Likewise, CGRP and AM appear to further an inflammation, at least with respect to the vascular effects and neurogenic inflammation.
Another target of neuroendocrine mediators are cutaneous mast cells. J. Bienenstock (S21) provided insight into the function of these important cells that are frequently located at body surfaces such as the skin or the intestine, which are exposed to the environment and serve to sense "foreign" molecules. Mast cells are even capable of regulating central nervous system functions, such as the release of hormones from the pituitary. By doing so, they help regulate the HPA axis and to orchestrate the complex and integrated stress responses required to maintain homeostasis.
However, a number of papers also focused on the anti-inflammatory potential of neuropeptides and neuroendocrine mediators, particularly for dendritic cell /T-cell mediated immunity. Cells of the innate immunity such as dendritic cells (DC) present antigens in the presence of MHC class II molecules to activate naïve T-cells. They also express cytokines and costimulatory molecules that prevent T-cell anergy. DC are susceptible not only to anti-inflammatory effects of glucocorticoids secreted by adrenal glands as part of the HPA axis. There is also considerable evidence that secondary lymphoid organs such as spleen or draining lymph nodes in the skin are densely innervate by sensory neurons. In addition, cutaneous sensory nerves directly contact immunocompetent cells such as epidermal Langerhans cells. C.L. Butts (S27), R. Granstein (S22) and M. Delgado (S24) discussed the effect of glucocorticoids and various neuropeptide mediators [CGRP, pituitary adenylate cyclase activating polypeptide (PACAP) or vasoactive intestinal peptide (VIP)] on antigen presentation, cytokine production and T-cell activation of Langerhans cells in vitro and the biologic relevance in vivo. At present, these peptides appear to impair LC and DC functions, and contribute to reduced cutaneous responses to allergens, or the induction of ultraviolet induced immunosuppression. As pointed out by M. Delgado, VIP and PACAP have a general anti-inflammatory role in both innate and adaptive immunity and do not only reduce expression of costimulatory molecules on antigen presenting cells. VIP/PACAP also appear to be capable of mediating a switch from a proinflammatory Th1 to a Th2 response and. These studies nurture the concept that neuropeptide mediators have emerged from being mere neurotransmitters to molecules that by exhibiting cytokine-like properties, have important immunomodulatory capacities in the skin and elsewhere. A number of studies also focused on the role of neuroendocrine and neuropeptide
mediators in disease. As J. Rees pointed out, certain allelic variants of the MC-1R bear an increased risk of developing skin cancer, particularly malignant melanoma. A. Eberle (S12) discussed the possibilities to track melanoma micrometastasis. This concept utilizes modified (radioactive or cytotoxic) MSH peptides that bind to highly MC-1R expressing melanoma cells and thus accumulate in tumors, but not in MC-1R negative tissues and can exert radiolytic and cytotoxic properties on melanoma cells. In another paper, W.D. Bowen (S13) presented sigma receptors as novel target structures for cancer chemotherapeutics.
These receptors (sigma 1 and 2) are either present on tumor cells or upregulated by rapidly dividing cells. Since activation of sigma-2 receptors triggers apoptotic cell death, subtoxic doses of sigma-2 R agonists are useful tools to sensitize tumor cells for subsequent treatment with chemotherapeutics. Likewise, the high density of these receptors on certain tumor cells makes them a target for the development of non-invasive tumor imaging agents. This could also be useful to track melanoma metastasis in the brain.
In the CNS, the presence or absence of neurotrophins and their receptors on metastatic melanoma cells highly influences the metastatic colonization of these cells. As pointed out by G.L. Nicolson (S14), melanoma lines with a high capacity to colonize the brain are characterized by high amounts of p75NTR (NGF low affinity receptor), and stimulation with NGF and other neurotrophin such as NT-3 stimulates release of matrix-degrading enzymes such as MMP-2 and heparanase and autocrine growths factors. In addition to that, paracrine growths factors finally determine whether metastatic melanoma cells can successfully invade, colonize and grow in the CNS. Another important target for neurotrophins such as brain-derived growth factor (BNDF), neurotrophin (NT)-3, -4 and -5 are epidermal ratinocytes. By activating high affinity trk receptors, NGF stimulates eratinocytes roliferation and protects keratinocytes from UV-light induced apoptosis.
On the contrary, BNDF or NT-4 induce keratinocyte apoptosis by activating low affinity p75 NTF receptors. These data presented by C. Pincelli (S34) indicate that NT have dual role in epidermal homeostasis.
Recent evidence from H. Renz and colleagues (S26) also indicated that production of neurotrophins (BNDF and NGF) is also increased in organs such as skin, gut and airways affected by allergies. Those chronic inflammatory diseases that are derived from an inappropriate response of an immune system to environmental antigens (allergens) are affected by increased NT derived from residential and migratory cells in a bi-directional way. According to the findings resulting from human and murine models of allergic asthma, H. Renz presented evidence that NT control function, neuropeptide production and survival of sensory nerve fibers, but also survival from apoptosis of inflammatory cells including eosinophils, and are involved in the differentiation and function of Blymphocytes in the affected tissue.
Varieties of mechanisms exist that terminate inflammatory and non-inflammatory effects of neuropeptides and neuro-endocrine hormones. Besides regulation or desensitization of corresponding receptors, clearance by proteolytic cleavage is one major way of terminating the local bioactivity of peptides mediators, which results in removal of these peptides from the vicinity of their receptors. T. Scholzen (S25) provided novel insight into the mechanisms of SP and NK-1R influencing cutaneous allergic contact dermatitis responses. From these studies novel evidence emerged that bradykinin and particularly SP via NK-1R is capable of boosting ACD sensitization by directly promoting migration, hapten uptake and antigen-presenting functions of dendritic cells involved in antigen sensitization. Consequently, incomplete removal of SP caused by transient or permanent inhibition of certain zinc-metalloproteases (neutral endopeptidase; NEP and angiotensin converting enzyme, ACE) results in exacerbated allergic inflammation. Likewise, NEP and ACE are also involved in the proteolytic cleavage of the stress hormone ACTH and the anti-inflammatory POMC peptides a-MSH indicating that peptidases have an important role in controlling skin inflammation.
In addition, the relative presence or absence of SP-proteolytic peptidase such as NEP also affects skin regeneration and wound healing after injury or disease. J.E. Olerud discussed (S32) how wound healing is impaired in patients with diabetic ulcers. These patients due to neuropathy not only lose epidermal and dermal sensory nerves that release SP, but also overexpress NEP in diabetic lesions. Consequently, due to an increased relative lack of cutaneous SP that has a beneficial effect on wound healing, a high number of patients suffer from non-healing ulcers and an increased risk of amputation.
Another important means to terminate inflammatory responses is the release of anti-inflammatory mediators such as interleukin-10, the IL-1 receptor antagonist or a-MSH. In his presentation, J.W. Haycock (S35) discussed the multiple effects a-MSH has as a prototypic natural occurring anti-inflammatory and anti-oxidative molecule. Accordingly, many of these effects result from the ability of a-MSH to antagonize NF-?B-mediated signal transduction by stimulating cAMP/PKA signal transduction following activation of the MC-1R. In addition, a-MSH prevents peroxide-stimulated activation of glutathione peroxidase suggesting an anti-oxidant role. However, in addition to its well-established role as an immunosuppressive, anti-pyretic and anti-inflammatory molecule, there is also evidence that a-MSH, being conserved through evolution, is an important component of the innate immune system by demonstrating antimicrobial properties. A. Catania et al. (S20) presented recent studies demonstrating that certain synthetic a-MSH analogues in comparison to a-MSH itself have even more pronounced antimicrobial activities against Candida and substantial antimicrobial effects against gram-negative and -positive bacteria.
Thus, these compounds may be a novel class of promising antibiotics in the future. M. Böhm (S35) and Z. Abdel-Malek (S36) highlighted another novel property of a-MSH.
Both authors independently discovered that a-MSH is capable of preventing apoptosis of melanocytes and keratinocytes induced by UVB irradiation. This survival effect is mediated by MC-1R/IP3 kinase pathway and occurs independent from melanogenesis.
Apparently, a-MSH also enhances DNA excision repair of UV-induced cyclobutane pyrimidine dimers and pyrimidine (6-4) pyrimidone photoproducts suggesting that a- MSH contributes to maintain the genomic stability and inhibits mutagenesis in photodamaged epidermal cells. Therefore, during the meeting a-MSH and the superpotent synthetic analogue NDP-a-MSH were discussed as potential promising tools for skin protection from UVB-light. Indeed, as suggested by S. M. Humphrey and colleagues (S44) in the final "Clinical Perspectives" Session, in recent double-blinded, randomized clinical trials utilizing exogenous NDP-a-MSH (Melanotan®) injected into the skin demonstrated profound skin protecting effects in comparison to placebo controls due to its potent eumelanin-inducing capacities. These studies suggest that Melanotan® may prove as a useful adjunct to current photo protective strategies against rising skin cancer incidences.
Another potential tool for skin protection from photo damage was proposed by R.J.
Reiter (S39). Melatonin is a powerful multifaceted free radical scavenger and indirect oxidant. Melatonin prevents progression and severity of disease in animal models of Alzheimer, Parkinsonism or cataract formation that are in part characterized by the loss of melatonin. Due to its anti-oxidative properties, exogenously applied melatonin on human skin may be a useful tool to reduce skin aging caused by lipid peroxidation or erythema induced by UV irradiation.
S. Ständer (S42) provided the participants with an overview on the current developments in the treatment of non-histamine-induced Pruritus, a difficult-to-treat cutaneous disturbance that either accompanies certain cutaneous diseases or acts as "stand alone" disorder. S. Ständer demonstrated that the novel findings of µ-opiate receptors and vanilloid receptor 1 (VR-1) on sensory nerves provides the basis for an effective and in ongoing studies successful treatment of patients with oral opiate receptor antagonists (naltroxon) or epicutaneous capsaicin. The latter, by activating VR-1 on sensory nerves triggers the release of sensory neuropeptides. Prolonged application of capsaicin results in depletion of nerves from neuropeptides and thus not only terminates of itch sensation but also contributes to healing of skin lesions in prurigo nodularis.
In summary, the presentations by invited guest speakers and session chair persons derived from the USA, Canada, Australia and Europe, all well known experts in the field of neurocutaneous biology and provided for a high standard, lively and fruitful scientific meeting that covered a most recent, highly relevant and active research area with many promising clinical applications for the future.

6. Composition of participants
Total number of participants: 149

Speakers & Chairs only
a) USA & Canada: 18 (35.3 %)
b) Europe 15 (29.4 %)
c) Germany (including organizers) 17 (33.3 %)
d) Australia 1 (2 %)
Total: 51 (= 100 %)
Poster Presenters:
a) USA & Canada: 5 (9.8 %)
b) Europe 19 (37.3 %)
c) Germany (including organizers) 25 (49.0 %)
d) Asia (Japan & Korea) 2 (3.9 %)
Total: 51 (= 100 %)

7. Conference expenses in EUR:
Traveling expenses for invited speakers: ................................................. 16,000.00
Other traveling expenses:
Accommodation for invited speakers: ...................................................... 9,790.00
Rental of the meeting place (includes lunches & coffee breaks) ............. 13,650.00
Secretarial expenses and miscellaneous (printing, postage, telephone) ... 1,682.00
Secretarial wages....................................................................................... 2000.00
Poster prizes............................................................................................... 750.00
Travel grants ............................................................................................. 1,610.00
Social events:
1. Picasso Museum:
a) Rental:.................................................................................................... 1,055.00
b) Catering 1................................................................................................ 4,649.00
2. Residency Erbdrostenhof
a) Rental: ............................................................................................. 1,200.00
b) Entertainment................................................................................... 1,500.00
c) Catering 2 ........................................................................................ 4,966.00
Total Expenses: …………….............................................................. 58,852.00

8. Conference income (in EUR):
Conference fees:.................................................................................... 4,550.00
Public support (Deutsche Forschungsgemeinschaft): .......................... 20,000.00
Private support (Sponsoring): .............................................................. 15,150.00
Other supports (Hertie-Foundation; ISN-CC): .................................... 11,400.00
Total Income: ....................................................……......................... 51,100.00

9. Usage of funds provided by the ISN-CC
a) Travel Grants: The following persons were provided with a travel fellowship
depending on personal needs:
o E. Bodo, University of Debrecen Dept. of Physiology, Debrecen, Hungary (250.00 EUR).
o J. Elliott, University of North Carolina at Chapel Hill, Dept. of Psychology, Chapel
Hill, USA (440.00 EUR).
o S.A. Elwary, University of Bradford, Dept. of Biomedical Sciences, Bradford, UK
(290.00 EUR).
o S. Kauser, University of Bradford, Dept. of Biomedical Sciences, Bradford, UK
(290.00 EUR).
o H. Kobayashi, University of Hamburg, Dept. of Dermatology, Hamburg, Germany
(150.00 EUR).
o K.M. Stieler, Charite, Dept. of Dermatology, Berlin, Germany (190.00 EUR).

b) Poster Prizes:
Prizes were selected during the meeting by an ad hoc poster committee consisting of J.C.
Ansel, Chicago, IL, USA, S.D. Brain, London, UK, and A. Slominski, Memphis, TN, USA
The following people were selected for a poster prize (3 x 250.00 EUR):
o H. Kobayashi, Hamburg, Germany (Poster #19)
o E.M.J. Peters, Berlin, Germany (Poster #48)
o M. Schiller, Münster, Germany (Poster #09)

c) Organizers expenses (in EUR):
Secretarial expenses/miscellaneous (printing, postage, telephone) ........... 1,682.00
Secretarial wages:....................................................................................... 2,000.00
Total from a) - c)...................................................................................... 6,042.00

10. Miscellaneous: The 1st International Meeting on Neurobiology of the Skin was/is intended as a start of a biannual conference series. As publicly announced in the final statement of the organizers on Sunday 15 during the meeting, the next conference is scheduled for Spring/Summer 2006 to take place again in Münster in order to firmly establish the series.
After 2006, the subsequent conferences will take place at various international locations that have to be determined.

Name and Signature of applicant Date: May 17, 2004

Thomas E Scholzen, Organizing Committee