Quantification of Cutaneous Sensory Nerves and Their Content in

Anita Naukkarinen, Ph.D., Brian J. Nickoloff, M.D., Ph.D., and Eugene M . Farber, M.D. Psoriasis Research Institute. Palo Alto, CaJifornia (AN,EMF); Department of Pathology. Stanford University Medical Center, Stanford, C.alifornia (AN); and Depanmenc of Pathology and Dermatology, University of Michigan Medical School, Ann Arbor, Michigan, U.S.A. (BJN)

The aim of the present study was to extend our previous in tissues, and its accual concentrations in the sections were hypothesis that the inflammatory reaction in psoriasis is neu­ unknown, there was an increase in substance P containing rogenic, and that substance P mediates the . nerves in the psoriatic lesion. the increase being significant in For this purpose, the pattern of neurofilamcnt-positive sen­ the epidermal nerve fibers. No significant differences in the sory nerve fibers was studied and the lengths and substance P measured parameters were obtained between lesion-free content of these fibers measured morphometrically in dermal psoriatic and control skin. and epidermal compartments of the psoriatic lesion, psoriatic These results indicate that there is an altered pattern of but lesion-free skin. and control skin. sensory nerves in a psoriatic plaque and that substance P may The epidermis and dermis of the psoriatic lesions were be an important mediator in the inflammatory processes that significantly more densely innervated with neurofilament­ contribute either to the initiation or maintenance of a psoria­ positive fibers than either lesion-free psoriatic or control tic lesion.] 111l1est DerlllatoI92:126-129, 1989 skin. Although substance P is known to be rapidly degraded

soriasis is a disorder of the total skin appearing in patients also more frequent in psoriatic lesions than in normal skin (14}. genetically predisposed to this disease [1]. Histologi­ Thus, c1emems for neurogenic inflammation seem to exist in a cally, psoriatic lesions are characterized by hyperplasia psoriatic lesion. In fact, abnormality and increased turnover of cuta­ and altered differentiation of the epidermis. dilated cap­ neous nerves in psoriasis has been previously reported by Weddell et illaries in the r.apillary dennis. and inflammation in both .1 [15J. dermisP and epidermis [2 . The disease is known to have exacerba­ The aim of the present study was to find out if the innervation tions and remissions affected by general changes occurrin~ in the pattern and the contenc of SP in the cutaneous nerves are altered in body, e.g., hormonal changes at puberty and menopause l3J, and psoriatic skin. For this, sections from psoriatic lesions, lesion-free various forms of stress [4,5]. This suggests the involvement of psoriatic, and control skin biopsies were stai ned immunohisto­ neural-derived factors in the pathogenesis of psoriatic lesions. The chemically and the nerve lengths measured morphometrically. symmetrical appearance of the lesions further suppOrtS this view [5]. When the role of the nervous system in inflammatory responses was MATERlAL AND METHODS studied, substance P (SP) was the first neuropeptide transmitter identified and purified. SP is synthesized in the dorsal root ganglia Biopsies Punch biopsies of 3 to 4 mrn were taken from lesional and transported to peripheral sensory nerve endings where it is skin of 15 psoriatic patiencs, lesion-free skin of seven psoriatic pa­ released by various stimuli [6]. The skin is richly innervated with tients, and concrol skin of nine persons. All the psoriatic patients unmyelinated sensory fibers, and SP has been localized in the free were adults representing both sexes and different age groups. The nerve endin~s in the dermal papillae and epidermis of healthy psoriatic biopsies were at different stages from non-digital skin. Psoriatic, but lesion-free skin was taken at least 2 cm in distance ~uman s~in l7.'8]. SP is the only effective neuroreptide shown to Induce hIstamine release from rat mast cells [9 . Cooperation of from a lesion. One lesional and one lesion-free biopsy were raken histamine and SP is suggested to result in the axOJl reflex, i.e., from the same psoriatic patient. Otherwise all the biopsies studied activation of sensory nerves leads to peripheral release ofSP, which were from different patients. Control skin was received from face in turn releases histamine from mast cells. and the released hista­ lift operations, all the donors being female (54.7 ± 4.6 years, M ± mine further excites other sensory neurons [1 OJ. In an early psoriatic SEM). Because site-matched biopsy material from healthy concrols lesion, one of the first morphologic changes observed by some in­ was not available, the face-lift skin was used because it has a rich vestigators is the dcgranuiating mast cell [t 1-13]. Mast cells are neurovascular supply. After removal, the biopsies were immediately immersed in saline, and within a few hours embedded in OCT Compound (Miles Scientific, Naperville. IL) and frozen in liquid Manuscript received January 14, 1988; accepted for publication July 22, nitrogen. The frozen biopsies were stored in -70°C umil further 1988. processed. This study was financed by The Psoriasis Research Institute and The National Science Foundation Immunohistochemical Stains For immunohistochemical Pan of this work has been presented at the World Congress ofDennatol- staining, 16.um cryosections were cut and placed on poly-L-Iysine 0gy, Berlin, May 24-29,1987. (Sigma Chemical Co., Sf Louis, MO) coated slides. Serial sections Reprint requests to: Anita Naukkarinen, Ph.D., Department of Clinical from the same biopsy were stained with both the polyclonal rabbit Pathology, Kuopio University Central Hospital. 70210 Kuopio-Finland antihuman neurofilament (NF) antibody (gift from Dr. Dahl, West

0022~202X /89 / S03.50 Copyright © 1989 by The Society for Investigative Dermatology, Inc.

126 VOL. 92, NO.1 JANUARY 1989 QUANTIFICATION OF NERVES IN PSORIATIC SKIN 127

Roxbury Veterans Administration Medical Center, Boston, MA). Statistics The results in each group STUdied arc expressed as the and [he polyclonal rabbit anti-human substance P (SP) antibody mean ± SEM, and Student's t test has been used in comparison of (Histo-Tek Antisera, Miles Scientific). The anti-NF antibody was the means. raised in rabbits against degraded anrigen from phosphate buffer extracts of autolyzed human spinal cord as discussed by Dahl and RESULTS Dignami [16]. This antiserum has been previously characterized in identification of sensory nerves in human skin [171. The stainings With the staining procedure used in the prese nt study, both NF and were carried out at room temperature. After a 10 min treatment SP positive fibers could be reproducibly observed in the sk in of the with normal goae serum, both antisera were used as a 1 : 1,000 dilu­ three different groups. tion on sections for 60 min. After a thorough rinse with phosphate­ The lengths measured of the NF positive fibers both in dermal buffered saline (PBS) a biotinylated goat anti-rabbit IgG (Vectastain and epidermal compartments were significantly greater in psoriatic ABC kit, PK-4001, Vector Laboratories, Burlingame, CA) was ap­ lesions (Group 1) than in lesion-free psoriatic (Group 2) or coorral plied on the sections for 30 min. After PBS rinses and a 5 min (Group 3) skin (Fig 1, Table I). hydrogen peroxide treatment an avidin-biotin-peroxidasc complex No significance was recorded in the dermal SP-positivity be­ (Vectastain ABC kit, PK-4001) was added on the sections for 40 Tween different groups. However, the measured epidermal SP-con­ min, followed by PBS rinses. The peroxidase enzyme was visualized taining nerve fibers summed up significantly higher in psoriatic by incubating the sections in 0.05% 3.3'-diaminobenzidine tetrahy­ lesions when compared to rhe other groups (Fig 2, Table I). No drochloride (Polysciences Inc., Warrington, PA) containing 0.04% significant differences in any of the measured parameters were ob­ nickel chloride and 0.03% hydrogen peroxide (Merck, Darmstadt, tained between Groups 2 and 3. Germany) for 5 min. Before coverslipping the sections were washed In Group '1, the NF positivity was quite frequently seen in the under running tap water for 3 min, dehydrated in ethanol series, and nerve fibers among the dermal inflammatory infiltrate, and in the cleared with xylene. Sections treated with normal rabbit serum epidermis as well (Fig. la). In Groups 2 and 3, NF positive fibers (1: 1,000) instead of anti-NF or and-SP antibodies were used as were observed in the dermis but very rarely in the epidermis (Figs negative controls. The slides were examined and photographed Ib,c). with a Leitz Dialux 22 microscope eq uipped with a Vario-Ortho­ In Group 1. SP positive nerve fibers were mainly localized in the mat camera. papillary dermis as short thin strands which occasionally extended into the epidermis (Fig 2). In Groups 2 and 3, faint SP positivities were observed in the dermis, and like NF positivity, very rarely in Morphometric Evaluation of tbe Stains The NF and SP posi­ the epidermis. dviTies were quantitated using a compurer-assisted image analysis system, which consisted of an Olympus BH-2 microscope with a DISCUSSION color camera attachment (Hitachi Color Camcra FP-3060A, Hita­ chi Denshi, Ldt.) and a Sony Trinitron monitor. Lengths of the Evaluation of cutaneous nerves in a histologic section is quite diffi­ positive nerves were measured by moving a cursor on a Hipad Digi­ cult because nerve fibers appear randomly and only partially in a tizer (Bausch & Lomb, Houston Instrument Div.) and simulta­ plane of section. Another difficulty is the relatively small number of neously following the trace of the cursor on the image of the sec­ nerves that can be observed on one section. There are ca. 100 free tion. which was projected on the monitor screen. The microscope, nerve endings per mm2 in a dermal papilla, and only 1-5 in the the monitor, and the digitizer were connected to an IBM Personal epidermis of human digital skin [t81. Also, fingertips and toes are Computer. much more densely innervated than other skin areas that were used One representative section on each slide was examined using a in rhis srudy. Presence of SP-containing nerve fibers has been re­ 20x objective. Five adjacent fields were analyzed, which usually ported in human skin, but they arc most abundant in fingers and toes covered the whole section. Each field consisted of an approximately l8l To overcome these problems in this study relatively thick sec­ equal area of dermis and epidermis. The lengths of the NF and SP tions (16 .um) were cut, and the lengths of rhe stained nerve fibers positive nerves were measured separately in dermis and epidermis in were measured morphometrica lly. However, sources of error still each specimen. exist, e.g., slight variation in section thickness is possible. and the

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•• r ~ . ~ , ; ,. ~ , y. • ""\ t • 1.1 " / I

a b.. ~ c • Figure 1. Sensory nerve fibers (arrows) in the skin. E: epidermis. Anti-neurofll:uncnf antibody (x 450). (a) Psoriatic lesion: A bundle of nerves can be seen in the dennis, thin fibers also c:m be seen within the thickened epidennis. (b) Lesion-free psoriatic skin. (r) Control skin. 128 NAUKKARINEN. NICKOLOFF. AND FARBER THE JOURNAL OF INVESTIGATIVE DERMATOLOGY

Table I. Lengths of the Positive Nerves (±SEM) and Their velopment of dermal papillary blood vessels. In fact, the absence of Significances as Tened against Group 1 significant alterations in lesion-free skin suggests that there may be a link ?crween the development of a psoriatic plaque and the altered Parameter Group Length (pm) p< and tTlcreased number of sensory nerves in the skin. Based on the current results, it cannot be determined whether the alteration in NP"

T/'t authors lVallt to tJltlllk ProjtJSor Klaus C. Bel/scI! (De/JlJrtmem oj Pathology, SrQIIJMJ Ullivwiry) for provicJitW r.wtllttlt facilirits Jor this Ulork, atld Dr. Molly j ohtllotl, Dr. Vera MorhetUl (Depa"ltIt'rll of Ckrmarology. Stanford UniL1trsity) , a"J Dr. j otl/Jrharl MatubriJge (Psoriasis Rtstorch trlstitutt, Palo Alto, CA) for kiPlJly supplying the biopsy ,"olfrlal. ------

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