Potent vasodilator activity of calcitonin gene-related peptide in human skin

We have recently shown that the novel neuropeptide calcitonin gene-related peptide, CGRP, is a potent vasodilator. In this paper we report a detailed study of the effects of CGRP in human skin. CGRP induces a clearly defined, long-lasting erythema. We have measured the effect of CGRP on blood flow in human skin using a laser Doppler technique and have demonstrated increased local blood flow that persists for a number of hours. We compared the response of CGRP with other known vasodilators [histamine, prostaglandin (PG) E2, PGI2, substance P, and vasoactive intestinal peptide (VIP)] in the skin, and in all subjects the erythema induced by CGRP was more persistent than that induced by the other mediators tested. Except at high doses the local vasodilatation induced by CGRP was not associated with a wheal and flare as seen with histamine, substance P, and VIP. CGRP is an extremely potent vasodilator and if released into the circulation, or locally from peripheral nerve endings, it could have a role in the regulation of blood flow in both physiologic and pathologic conditions; CGRP may be the endogenous mediator of the flare in the triple response. A deficiency in CGRP secretion or action could be an important component of peripheral vascular disease. Some flushing reactions (e.g., those associated with medullary thyroid carcinoma) may result from circulating CGRP.     

Some effects of calcitonin gene-related peptide in human skin and on histamine release

Calcitonin gene-related peptide (CGRP) produced a dose-related wheal and flare reaction in human skin at doses of 12.5 to 50 pmol. The flare response but not the wheal response to CGRP and substance P were inhibited by prior treatment of the subject with oral chlorpheniramine, 16 mg. CGRP, but not substance P, was potent in producing a delayed erythema and surrounding pallor in human skin, which peaked at 1 h and persisted for more than 3 h after injection, when wheal and flare responses had subsided. The delayed response was accompanied by infiltration of polymorphonuclear leukocytes. The delayed erythema and pallor produced in response to CGRP were not inhibited by oral chlorpheniramine, or by 4% prilocaine injected locally. CGRP released histamine from rat peritoneal mast cells over the concentration range 2.5-10 microM. CGRP was about fourfold less potent than substance P in releasing histamine. The substance P analogue, [D-Pro4, D-Trp7,9,10]SP4-11 10 microM, and benzalkonium chloride 10 microM inhibited histamine release from rat mast cells stimulated by either CGRP or substance P.     

Acute effects of substance P and calcitonin gene-related peptide in human skin--a microdialysis study

Upon activation nociceptors release neuropeptides in the skin provoking vasodilation and plasma protein extravasation in rodents, but only vasodilation in humans. Pivotal peptides in the induction of neurogenic inflammation comprise calcitonin gene-related peptide and substance P, the latter being suggested to act partly via degranulation of mast cells. In this study substance P and calcitonin gene-related peptide-induced vasodilation, protein extravasation, histamine release, and sensory effects were investigated simultaneously in human skin by dermal microdialysis. The vasodilatory prostaglandin E(2) and the mast cell activator codeine served as positive controls. Substance P and calcitonin gene-related peptide applied intradermally via large cut-off plasmapheresis capillaries induced dose-dependent local vasodilation, but only SP provoked protein extravasation in concentrations greater than 10(-9) M. Substance P-induced (10(-8)-10(-6) M) protein extravasation was not accompanied by histamine release and was unaffected by cetirizine (histamine H1 blocker, 200 microg per ml). Only the highest concentration of substance P (10(-5) M) induced significant histamine release. Neither neuropeptide caused any axon reflex erythema or any itch or pain sensation, whereas mast cell degranulation by codeine dose dependently provoked itch, flare, protein extravasation, and histamine release. In human skin calcitonin gene-related peptide and substance P induce vasodilation by a mechanism not involving histamine. No evidence for neuropeptide-induced activation of nociceptors was obtained. Our results suggest that endogenous calcitonin gene-related peptide and substance P have no acute sensory function in human skin. The lack of neurogenic protein extravasation in humans can most probably be attributed to low local concentrations of this neuropeptide still sufficient to exert trophic and immunomodulatory effects (10(-11) M), but too low to induce protein extravasation (10(-8) M) or even mast cell degranulation (10(-5) M). J Invest Dermatol 115:1015-1020 2000     

降钙素基因相关肽对HaCaT细胞表达血管内皮生长因子的调控

目的 探讨降钙素基因相关肽(CGRP)对角质形成细胞表达和分泌血管内皮生长因子(VEGF)的调控.方法 用实时定量PCR(RT-PCR)方法检测CGRP、CGRP1型受体拮抗剂CGRP8-37、细胞外信号调节激酶ERK1/2特异性的抑制剂PD98059、p38MAPK特异性拮抗剂SB203580对HaCaT角质形成细胞表达VEGFmRNA水平的影响;用酶联免疫吸附方法检测HaCaT细胞分泌至培养液中VEGF蛋白的水平.结果 CGRP时间依赖性地促进HaCaT细胞表达VEGFmRNA和分泌VEGF蛋白;CGRP8-37和PD98059均可明显抑制CGRP刺激的HaCaT细胞表达和分泌VEGF,SB203580不能减弱CGRP刺激的VEGF表达和分泌.结论 CGRP可以上调HaCaT细胞表达和分泌VEGF,CGRP1型受体及其相关的ERK1/2信号通路参与其调控.     

降钙素基因相关肽对朗格汉斯细胞功能影响的研究进展

在慢性炎症性皮肤病的神经免疫调节过程中,神经肽对于皮肤免疫细胞的调节作用受到越来越多的重视.在精神紧张、应激和压力的作用下,皮肤局部神经纤维产生降钙素基因相关肽,调节皮肤的朗格汉斯细胞.朗格汉斯细胞是表皮中重要的专职抗原提呈细胞.近年来发现,降钙素基因相关肽不仅可以影响朗格汉斯细胞的增殖、分化,而且影响其抗原提呈功能.降钙素基因相关肽可以抑制朗格汉斯细胞核因子κB通路的活化、抑制其协同刺激分子的表达,进而影响朗格汉斯细胞介导的免疫反应.     

Cutaneous vascular response to calcitonin gene-related peptide in psoriasis and normal subjects

To determine whether cutaneous blood vessels in subjects with psoriasis possess a generalized inherently abnormal response to neuropeptides, the effect of three doses of intradermally injected calcitonin gene-related peptide (CGRP) on skin blood flow in normal subjects (n= 10), and on clinically normal skin (greater than 5 cm from psoriatic lesions) in subjects with psoriasis (n= 9) was measured using a laser Doppler technique. Calcitonin gene-related peptide caused a dose-dependent increase in local blood flow in both psoriatic and normal subjects, which was not statistically different between the two groups. This study has shown that the cutaneous vasculature at sites distant from lesions of psoriasis (> 5 cm) is not inherently different from normal skin in its response to CGRP.     

Upregulation of nitric oxide synthase in cultured human keratinocytes after ultraviolet B and bradykinin

Kang-Rotondo CH, Major S, Chiang TM, Myers LK, Kang ES. Upregulation of nitric oxide synthase in cultured human keratinocytes after ultraviolet B and bradykinin. Photodermatol Photoimmunol Photomed 1996: 12: 57–65. © Munksgaard, 1996. Ultraviolet B (UVB) irradiation of the skin has been reported to upregulate nitric oxide synthase (NOS) activity with enhancement of nitric oxide (NO) formation. Bradykinin, a known stimulator of NO production, is produced in the skin within minutes of UVB irradiation. The combined effect of UVB and bradykinin on NOS was therefore examined in a cultured human keratinocyte (KC) line. Activity was determined in KC homogenates by the recovery of [³H]l -citrulline using labeled l -arginine as the substrate in the presence of mM NADPH. Monoclonal antibodies to specific isoforms of NOS that cross-react with their human counterparts were used to determine the isoform(s) in control, UVB, bradykin treated and UVB and bradykinin treated KC. Human KC express NOS activity which is lowest at confluence and highest during proliferation. UVB increased NOS activity when a set dose of irradiation was administered from 32.2–48.3 mJ/cm² but was inhibitory after 64.4 and 80.5 mJ/cm². Thirty min after 10^?6 M bradykinin, NOS activity nearly doubled followed by return of activity to control levels at 60 min. Activity after UVB and bradykinin was only slightly higher than that observed with bradykinin alone. Immunochemically, an isoform of M_r 155 kDa was detected in control cells with the antibody for the constitutive brain enzyme, bNOS. Recovery of this isoform increased after UVB treatment as well as after bradykinin which was time dependent. When both stimulants were used, the recovery of the 155 kDa enzyme was markedly enhanced, unlike the enzyme activity findings. These data indicate that the expression of NOS activity under unstimulated conditions in human KC in culture is due to the constitutive NOS found in neuronal tissue, bNOS. The recovery of bNOS increased after UVB and after bradykinin while the combination of both resulted in the synergistic increase in bNOS protein with only a marginal further increase in NOS activity.     

Increased synthesis of calcitonin gene-related peptide stimulates keratinocyte proliferation in murine UVB-irradiated skin

Repeated ultraviolet (UV) irradiations have been shown to induce keratinocyte proliferation with acanthosis, stimulate the cutaneous nerve proliferation, and increase the synthesis of calcitonin gene-related peptide (CGRP). In the current study, we examined the role of CGRP in the UVB-induced proliferation of murine keratinocytes. UVB irradiation increased the number of bromodeoxyuridine (BrdU)-labeled basal keratinocytes and caused acanthosis. In addition, CGRP expression was up-regulated in the peripheral nerves of the upper dermis and lower epidermis. Repeated intradermal injections of CGRP increased the number of BrdU-labeled basal cells and caused acanthosis. Intradermal injections of capsaicin prior to UVB-irradiation inhibited the UVB-induced CGRP expression, BrdU labeling in basal keratinocytes and epidermal thickening. Intradermal injections of anti-CGRP antibody inhibited the UVB-induced BrdU labeling in basal keratinocytes, but epidermal thickening was not significantly inhibited. These results indicate that CGRP is one of the stimulators to UVB-induced keratinocyte proliferation. On the other hand, expression of substance P, another neuropeptide in the peripheral nerve, was not up-regulated by UVB irradiation.     

Tachykinins and calcitonin gene-related peptide in oxazolone-induced allergic contact dermatitis in mice.

Neuropeptides in primary afferent neurons have been found to be engaged in the immediate type of hypersensitivity. However, their role in the delayed form of hypersensitivity is not yet established. The hypothesis that substance P (SP), neurokinin A (NKA), and calcitonin gene-related peptide (CGRP) are involved in delayed hypersensitivity was tested in oxazolone-induced, murine ear allergic contact dermatitis. Concentrations of immunoreactive SP, NKA, and CGRP were measured in extracts of the eczema ears (n = 26), whereas extracts of the opposite ears were used as controls. The SP, NKA, and CGRP contents in the treated ears were on the average 28% (p = 0.001), 32% (p = 0.004), and 15% (p = 0.016), respectively, lower than in the control ears. Lower peptide concentrations in the eczema ears indicate increased release of the peptides because the peptides are rapidly metabolized locally when released and only replenished by axonal transport from the cell bodies. Our results indicate that peptides released from primary afferent neurons play a role in the delayed type of hypersensitivity reactions.     

神经肽CGRP对银屑病单核细胞趋化功能的调节

为探讨神经肽对银屑病免疫细胞的调节，及其在银屑病神经免疫发病机制中的作用，本研究利用体外细胞培养技术分离培养单核细胞，分别加入外源性神经肽降钙素基因相关肽（calcitonin gene-related peptide,CGRP)及其受体拮抗剂CGRP8－37。用ELISA检测培养单核细胞上清液中趋化因子的含量；利用微型趋化小室，观察CGRP对单核细胞趋化活性的调节。结果CGRP诱导银屑病活化的单核细胞分泌趋化因子巨噬细胞炎性蛋白－1α(macrophage inflammatory protein-1α，MIP-1α）和单核细胞趋化性蛋白－1α（monocyte chemotactic protein-1α,MCP-1α)增加，受体拮抗剂CGRP8－37则抑制这种诱导作用，同时CGRP促进单核细胞对淋巴细胞和中性粒细胞的趋化活性，用CGRP8－37后则趋化活性减弱。提示银屑病皮损内神经肽CGRP可以通过受体诱导单核巨噬细胞分泌MIP－1α和MCP－1α趋化因子，使淋巴细胞和中性料细胞在局部皮损区定向迁移与聚集，促进局部炎性细胞的浸润。     

Intraepidermal nerve fiber expression of calcitonin gene-related peptide, vasoactive intestinal peptide and substance P in psoriasis

In order to evaluate more fully the role of neuropeptides in the pathogenesis of psoriasis, skin biopsies were obtained from 36 patients with psoriasis to identify substance P (SP), vasoactive intestinal peptide (VIP) and calcitonin gene-related peptide (CGRP). Lesional and nonlesional skin was examined from these biopsies and the results compared with those from biopsies taken from patients with a variety of other inflammatory dermatoses, including lichen planus, lichen simplex chronicus, spongiotic dermatitis, and seborrheic dermatitis. Also studied was a series of nine biopsies taken from patients with no known skin disorders. We found an increase in the number of SP-positive nerve fibers within the epidermis in biopsies from lesional skin of psoriasis patients (8.4 nerves per 3-mm biopsy) compared with nonlesional psoriatic skin (2.6 nerves per 3-mm biopsy) and normal skin (2.0 nerves per 3 mm biopsy). Other inflammatory disorders also demonstrated fewer SP-positive nerves than lesional psoriatic skin; lichen planus (0 nerves per 3 mm biopsy) and lichen simplex chronicus (1.3 nerves per 3 mm biopsy). The difference in SP-positive nerve expression between lesional psoriatic skin and the group comprising nonlesional skin, normal skin, lichen planus, and lichen simplex chronicus attained statistical significance ( P < 0.013). SP-positive intraepidermal nerve fibers in lesional psoriatic specimens were fewer than in spongiotic dermatitis (17.4 nerves per 3 mm biopsy). There was no significant difference in numbers of VIP- or CGRP-immunopositive intraepidermal nerve fibers between psoriatic skin and the group comprising all other material tested. However, in five patients with psoriasis, there was a marked increase in the expression of intraepidermal CGRP (up to 10.7 nerves per 3-mm biopsy) and VIP (up to 8.3 nerves per 3-mm biopsy) which was not observed in control groups. These findings suggest that neuropeptides SP, CGRP, and VIP play a role in the pathogenesis of psoriasis. Received: 3 March 1997     

Expression of nitric oxide synthases in keratinocytes after UVB irradiation

The importance of nitric oxide (NO) in mediating vasodilation, neurotransmission, and immune and inflammatory responses has been demonstrated. Human keratinocyte express inducible nitric oxide synthase (iNOS) and the neuronal constitutive isoform of NOS (ncNOS). We established an in vitro model in keratinocytes to investigate changes in NO, iNOS and ncNOS expression after UVB exposure. We demonstrated a large induction of NO after UVB exposure and that the source of NO produced in UVB-exposed keratinocytes was increased expression of iNOS and ncNOS. The increased NO production with increased expression of iNOS and ncNOS may contribute to the pathological and physiological features of UVB-induced erythema and skin inflammation.     

Occurrence of substance P,vasoactive intestinal peptide,and calcitonin gene-related peptide in dermographism and cold urticaria

Summary Substance P (SP), calcitonin gene-related peptide (CGRP), and vasoactive intestinal peptide (VIP) were assayed in lesions and normal skin of patients with dermographism and cold urticaria utilizing suction-induced blisters. There was no difference in SP and VIP concentrations between challenged and control skin of urticaria patients. On the whole, however, the concentration of both neuropeptides, and VIP in particular, was higher in the urticaria patients than in control subjects. CGRP levels were not increased. SP and VIP in blood samples from veins draining challenged skin areas were below the detection limit. It is concluded that SP and VIP may potentiate histamine in wheal formation and thus contribute to the increased reactivity of the skin to trauma and temperature changes in patients with physical urticaria.     

The role of calcitonin gene-related peptide in cutaneous immunosuppression induced by repeated subinflammatory ultraviolet irradiation exposure

Ultraviolet (UV) light is an effective treatment for skin disorders like psoriasis in which the cutaneous neurosensory system may have a pathogenic role. In this study, we examined the possibility that UV modulation of the cutaneous neurosensory system and calcitonin gene-related peptide (CGRP) may contribute to local immunosuppression mediated by repeated subinflammatory UV irradiation. Our results indicated that exposure of hairless mice to subinflammatory UV three times weekly for 4 weeks significantly increased the number of epidermal nerve fibers (ENFs) immunoreactive for CGRP without altering the total number of ENFs. The skin content of CGRP as measured by enzyme-linked immunosorbent assay was also significantly increased after exposure to this dose of UV. These effects were most apparent 1 day after the last UV exposure and declined 1 week after UV. The role of CGRP in UV-induced immunosuppression of contact hypersensitivity was then examined. Our results indicated that UV suppression of epicutaneous 2,4-dinitro-1-fluorobenzene (DNFB) sensitization could be significantly inhibited by a systemically administered CGRP receptor antagonist. A broad-spectrum sunscreen applied before UV exposure inhibited increased cutaneous CGRP and blocked immunosuppression. These findings support a role for CGRP in the local immunosuppression caused by chronic, repeated subinflammatory UV exposure.     

白癜风患者血浆与皮肤疱液降钙素基因相关肽测定

降钙素基因相关肽（CGRP）是重要的神经递质及免疫调节因子。研究旨在观察其是否可能与白癜风的发病有关。采用放射免疫分析法测定40例白癜风血浆CGRP浓度，并与正常对照作比较；同时测定部分患者白斑与非白斑处皮肤疱液CGRP浓度。结果显示寻常型与进展期白癜风血浆CGRP水平增高，白斑与非白斑处皮肤疱液其浓度无差别，认为CGRP与白癜风的发病可能存在一定关系。     

Cytotoxic effect on human keratinocytes caused by anti-Ro-(SS-A) antibodies and UVA in vitro

It is supposed that anti-Ro(SS-A) antibodies play an important role in the development of photosensitive skin disease in subacute cutaneous lupus erythematosus and neonatal lupus erythematosus. The aim of the experiments was to demonstrate that anti-Ro(SS-A) antibodies and UVA-light cause a cytotoxic effect on human keratinocytes in vitro. Keratinocytes are irradiated with UVA-light in presence of serum containing anti-Ro(SS-A) antibodies (62 E, ELISA). After application of 20 J/cm2 UVA-light only 48.5% of the irradiated cells are still vital (standard trypan blue exclusions test). Examination by scanning electron microscopy shows plain depressions on the surface of the keratinocytes, which were irradiated in presence of anti-Ro(SS-A) antibodies.