Expression of substance P receptors in normal and psoriatic skin

Excimer light effect on neurogenic inflammation in active versus stable psoriasis lesions

Neurogenic inflammation, mediated by T helper 17 cell (Th17) and neurons that release neuropeptides such as substance P (SP), is thought to play a role in the pathogenesis of psoriasis. Excimer light is used in the treatment of psoriasis via induction of T cell apoptosis. The objective of this study is to study the effect of excimer light on active versus stable psoriasis and investigate the levels of substance P and its receptor in both groups. The study included 27 stable and 27 active psoriatic patients as well as 10 matched healthy controls. Clinical examination (in the form of local psoriasis severity index (PSI) and visual analogue scale (VAS)) was done to determine disease severity, level of itching, and quality of life. Tissue levels of SP and neurokinin-1 receptor (NK-1R) were measured by ELISA before and after 9 excimer light sessions in 43 patients. A statistically significant lower levels of PSI and VAS were reached after therapy with no significant difference between the stable and active groups. The mean tissue levels of SP before therapy were significantly higher than the control group. Lower levels of SP and NK-1 receptor were found after treatment overall and in each group. Excimer therapy can be effective for both stable and active plaque psoriasis and this effect could be partly through its role on ameliorating the neurogenic inflammation.

Neurotransmitters, neuropeptides and their receptors interact with immune response in healthy and psoriatic skin

Psoriasis is a chronic inflammatory disease with a multifactorial origin that affects the skin. It is characterized by keratinocyte hyperproliferation, which results in erythemato-squamous plaques. Just as the immune system plays a fundamental role in psoriasis physiopathology, the nervous system maintains the inflammatory process through the neuropeptides and neurotransmitters synthesis, as histamine, serotonin, calcitonin gene-related peptide, nerve growth factor, vasoactive intestinal peptide, substance P, adenosine, glucagon-like peptide, somatostatin and pituitary adenylate cyclase polypeptide. In patients with psoriasis, the systemic or in situ expression of these chemical mediators and their receptors are altered, which affects the clinical activity of patients due to its link to the immune system, provoking neurogenic inflammation. It is important to establish the role of the nervous system since it could represent a therapeutic alternative for psoriasis patients. The aim of this review is to offer a detailed review of the current literature about the neuropeptides and neurotransmitters involved in the physiopathology of psoriasis.

Botulinum Toxin in the Field of Dermatology: Novel Indications

Since its approval by the US Food and Drug Administration in 2002 for glabellar wrinkles, botulinum toxin (BTX) has been widely used to correct facial wrinkles. As a result, many consider BTX synonymous with cosmetic dermatology. Recent studies indicate that BTX elicits biological effects on various skin cell types via the modulation of neurotransmitter release, and it seems that BTX has a wider zone of dermatologic influence than originally understood. Clinicians and researchers are now beginning to explore the potential of BTX beyond the amelioration of facial lines and encouraging results are seen with BTX in a variety of skin conditions. In this paper, we review novel dermatological indications of BTX which includes (but not limited to) scar prevention, facial flushing, post-herpetic neuralgia and itch. These areas show great promise, but there is definite need for larger, double-blinded, randomized control trials against established treatments before BTX becomes a clinical reality.

[Pruritus in psoriasis : Profile and therapy]

Psoriasis is a common chronic inflammatory disease with an incidence of about 0.5-3 %. Previously psoriasis was not primarily regarded to be associated with pruritus; however, this perception has changed in recent years. Meanwhile data conclusively show that between 64 and 97 % of patients report about pruritus that can be severe in a number of cases. Apart from suffering from psoriasis, the presence of pruritus causes additional stress and leads to a significant impairment of health-related quality of life. Neurogenic inflammation at least in part contributes to the development of pruritus in psoriasis skin lesions. A number of neuropeptides including substance P and calcitonin gene related peptide can act as pro-inflammatory mediators. There is evidence for a dysbalance between κ‑ and µ‑opioid receptors in lesional skin favoring inflammation and pruritus. After clearing of psoriasis lesions, pruritus is relieved as well. Therefore, specific treatment of pruritus is not necessary in general. In cases where severe pruritus is a prominent symptom, targeted therapy with mirtazapin or doxepin or neuroleptic compounds such as pregabalin or gabapentin or drugs affecting the κ‑ und µ‑opioid receptor balance can be administered. Today the importance of pruritus as a prominent symptom of psoriasis lesions has been widely accepted. In recent and running clinical trials with new drugs, pruritus at baseline and the effect of these drugs on pruritus is always assessed. This awareness also fuels basic research about pruritus in psoriasis.

Dynamics of expression rates of growth factor proteins in psoriatic patients receiving a phototherapy

Goal. To study the dynamics of expression rates of growth factor proteins in psoriatic patients receiving the PUVA therapy. Materials and methods. The authors conducted a study of 30 patients with psoriasis vulgaris treated with the PUVA therapy. The psoriasis severity and extent of itching were assessed prior to and after the treatment by the PASI index and visual analogue scale, respectively. The expression of semaphorin 3A, amphiregulin, nerve growth factor and PGP 9.5 protein (a nerve fiber marker) in the skin was assessed by the indirect immunofluorescence method. The expression of PGP 9.5 protein was used to assess the quantity and mean length as well as average and total fluorescence intensity of nerve fibers. Results. An increased expression of amphiregulin and nerve growth factor as well as increase in the quantity, mean length and average and total fluorescence intensity of nerve fibers were revealed in the epidermis of psoriatic patients. Following a course of the PUVA therapy, a decrease in the PASI index and extent of itching, reduced expression of amphiregulin and nerve growth factor as well as reduced quantity, mean length and average and total fluorescence intensity of nerve fibers in the epidermis were observed. Direct correlation dependence between the extent of itching, amphiregulin and nerve growth factor expression level and quantity and length of nerve fibers in the epidermis was discovered. Direct correlation dependence between the amphiregulin and nerve growth factor expression level, and average length of nerve fibers in the epidermis was discovered. Conclusion. The itching intensity in psoriatic patients receiving the PUVA therapy is reduced due to the decreased skin expression of the nerve growth factor and amphiregulin.

Immunohistochemical analysis of neuropeptides (protein gene product 9.5, substance P and calcitonin gene-related peptide) in hypertrophic burn scar with pain and itching

BACKGROUND

Neuropeptides have been recently reported as having an important role in wound repair, and relief from pain and itching sensation. The aim of this study was to evaluate the effect of neuropeptides on the wound healing process in hypertrophic scar formation that accompanies severe pain and itching sensation.

METHODS

We collected forty-three hypertrophic scar specimens from hypertrophic scar release and skin graft under general anesthesia. Immunohistochemical stains for protein gene product (PGP) 9.5, substance P (SP), and calcitonin gene-related peptide (CGRP) were performed. Pain and itching over the scar were recorded using verbal numerical rating scale (VNRS).

RESULTS

In the epidermis, PGP 9.5, SP, and CGRP were significantly increased in hypertrophic scars compared with matched unburned skin. In the reticular dermis, SP and CGRP were significantly increased in hypertrophic scars compared with control. The pain and itching verbal numerical rating scale in scar group were significantly higher compared to control. In the papillary dermis, the PGP represented significant correlation with Itching P (correlation coefficient 0.698) and the SP represented significant correlation with pain N (correlation coefficient -0.671). In the reticular dermis, the SP represented significant correlation with pain N (correlation coefficient -0.614) and CGRP represented significant correlation with pain P/Itching P (correlation coefficient 0.801/0.611).

CONCLUSIONS

Neuropeptides such as PGP 9.5, SP, and CGRP seem to affect scarring via sensory neurotransmission, it have a regulatory role for pain and itching sensation in hypertrophic scars.

Neuropeptides contribute to peripheral nociceptive sensitization by regulating interleukin-1β production in keratinocytes

BACKGROUND

It is increasingly evident that there is a close connection between the generation of cutaneous inflammatory cytokines and elevated neuropeptide signaling in complex regional pain syndrome (CRPS) patients. Previously, we observed in the rat tibia fracture model of CRPS that activation of caspase-1 containing NALP1 inflammasomes was required for interleukin (IL)-1β production in keratinocytes, and that administration of an IL-1 receptor antagonist (anakinra) reduced the fracture-induced hindpaw mechanical allodynia. We therefore hypothesized that neuropeptides lead to nociceptive sensitization through activation of the skin's innate immune system by enhancing inflammasome expression and caspase-1 activity.

METHODS

We determined whether the neuropeptides substance P (SP) and calcitonin gene-related peptide (CGRP) require IL-1β to support nociceptive sensitization when injected into mouse hindpaw skin by testing mechanical allodynia. We then investigated whether these neuropeptides could stimulate production of IL-1β in a keratinocyte cell line (REKs), and could increase the expression of inflammasome component proteins including NALP1 and caspase-1. Finally, we determined whether neuropeptide-stimulated IL-1β production required activation of caspase-1 and cathepsin B.

RESULTS

Intraplantar injections of SP and CGRP lead to allodynia in mouse hindpaws but CGRP was approximately 10-fold less potent in causing this response. Moreover, systemic administration of the IL-1 receptor (IL-1R) antagonist anakinra prevented sensitization after neuropeptide injection. Also, mouse skin keratinocytes express IL-1R, which is up-regulated after local neuropeptide application. In vitro data demonstrated that both SP and CGRP increased IL-1β gene and protein expression in REKs in a dose-dependent manner. Furthermore, SP time- and dose-dependently up-regulated NALP1 and caspase-1 mRNA and protein levels in REKs. In contrast, CGRP time- and dose-dependently enhanced NALP1 and caspase-1 mRNA levels without causing a significant change in NALP1 or caspase-1 protein expression in REKs. Inhibition of caspase-1 activity using the selective inhibitor Ac-YVAD-CHO reduced SP and, less effectively, CGRP induced increases in IL-1β production in REK cells. The selective cathepsin B inhibitor CA-74Me inhibited neuropeptide induced IL-1β production in REKs as well.

CONCLUSIONS

Collectively, these results demonstrate that neuropeptides induce nociceptive sensitization by enhancing IL-1 β production in keratinocytes. Neuropeptides rely on both caspase-1 and cathepsin B for this enhanced production. Neurocutaneous signaling involving neuropeptide activation of the innate immunity may contribute to pain in CRPS patients.

IL-33 augments substance P-induced VEGF secretion from human mast cells and is increased in psoriatic skin

The peptide substance P (SP) has been implicated in inflammatory conditions, such as psoriasis, where mast cells and VEGF are increased. A relationship between SP and VEGF has not been well studied, nor has any interaction with the proinflammatory cytokines, especially IL-33. Here we report that SP (0.1-10 microM) induces gene expression and secretion of VEGF from human LAD2 mast cells and human umbilical core blood-derived cultured mast cells (hCBMCs). This effect is significantly increased by coadministration of IL-33 (5-100 ng/mL) in both cell types. The effect of SP on VEGF release is inhibited by treatment with the NK-1 receptor antagonist 733,060. SP rapidly increases cytosolic calcium, and so does IL-33 to a smaller extent; the addition of IL-33 augments the calcium increase. SP-induced VEGF production involves calcium-dependent PKC isoforms, as well as the ERK and JNK MAPKs. Gene expression of IL-33 and histidine decarboxylase (HDC), an indicator of mast cell presence/activation, is significantly increased in affected and unaffected (at least 15 cm away from the lesion) psoriatic skin, as compared with normal control skin. Immunohistochemistry indicates that IL-33 is associated with endothelial cells in both the unaffected and affected sites, but is stronger and also associated with immune cells in the affected site. These results imply that functional interactions among SP, IL-33, and mast cells leading to VEGF release contribute to inflammatory conditions, such as the psoriasis, a nonallergic hyperproliferative skin inflammatory disorder with a neurogenic component.

Mediators of pruritus in psoriasis

The pathogenesis of pruritus in psoriasis remains unclear. Many possible mediators were implicated to transmit or modulate this sensation in psoriasis, but none has been clearly proven to be a causative agent of itching. The most often discussed theory mentioned the importance of impaired innervations and neuropeptides imbalance in psoriatic skin. Other possible causes of itching might be increased expression of interleukin 2 or vascular abnormalities. Recent data indicated that pruritus could be also evoked by opioid system, prostanoids, interleukin 31, serotonin, or proteases. Whether these mechanisms are also involved in pruritus accompanying psoriasis requires further investigation. Limited knowledge of pruritus origin in psoriasis is responsible for the lack of the effective antipruritic treatments for psoriatics. Here, we summarize the current knowledge about the pathogenesis of pruritus in psoriasis and point out possible directions of future studies aiming the pathogenesis of this symptom in psoriasis.

Plasma concentration of selected neuropeptides in patients suffering from psoriasis

The aim of this study was to evaluate plasma levels of substance P (SP), calcitonin gene-related peptide (CGRP), vasoactive intestinal peptide (VIP) and neuropeptide Y (NPY) during psoriasis course.

METHODS

Seventy-three patients with psoriasis and 32 healthy volunteers were included. Detailed demographic and disease anamnesis was obtained from every patient. The disease severity was assessed using the Psoriasis Area and Severity Index score. Plasma levels of SP, CGRP, VIP and NPY were measured radioimmunologically.

RESULTS

Plasma levels of SP and NPY did not significantly differ between patients with psoriasis and controls (median SP: 52.8 and 57.9 pg/ml, respectively; P = 0.32; median NPY: 8.5 and 8.2 pg/ml, respectively; P = 0.67). CGRP plasma concentration was significantly elevated in psoriatic individuals both before (median 43.1 pg/ml) and after treatment (median 45.4 pg/ml), in comparison with healthy donors (median 13.5 pg/ml; P < 0.01 and P = 0.03, respectively). Treatment did not significantly influence plasma CGRP levels (P = 0.3). Median VIP plasma concentration in psoriatics before treatment was significantly higher compared with healthy controls (medians 66.9 and 60.1 pg/ml, respectively; P = 0.04), but the therapy resulted in significant decrease in VIP plasma level (median 19.0 pg/ml; P < 0.001). In psoriatic patients significant correlations were noted between NPY and VIP (R = 0.34; P < 0.01), and VIP and CGRP plasma levels, both before (R = 0.28; P = 0.03) and after the treatment (R = 0.44; P < 0.01).

CONCLUSIONS

Based on our results and previous literature data it could be suggested that neuropeptides may be involved in the development of psoriatic lesions.

Study of substance P and its receptor neurokinin-1 in psoriasis and their relation to chronic stress and pruritus

Substance P and its receptor(R) neurokinin (NK)-1 may have a role in the pathogenesis of psoriasis. Stress has been reported to play a role in the onset and exacerbation of psoriasis, which might include the substance P-NK-1 receptor(R) pathway. A feature of psoriasis, that has been correlated to the severity of stress and secretion of substance P, is pruritus. The objective of this study was to investigate the expression of substance P and the NK-1R in involved and noninvolved psoriatic skin, using a biotinylated streptavidin technique. Moreover, a possible correlation between the patient s level of chronic stress, measured by salivary cortisol samples, degree of lesional pruritus, measured by means of a visual analogue scale, and the expression of substance P- and the NK-1R, was investigated. There was a low number of substance P positive nerve fibres in noninvolved and involved skin, the major immunoreactivity for substance P being found in inflammatory cells. The number of substance P- and NK-1R positive inflammatory cells was increased in involved compared to noninvolved psoriatic skin. The substance P positive cells were mostly lymphocytes, while most of the NK-1R positive cells were mast cells. NK-1R immunoreactivity was also seen as a reticular pattern in the upper part of the epidermis of involved skin in the majority of the patients. Low cortisol ratios in the patients, being an indicator of chronic stress, were correlated to an increased number of substance P- and NK-1R positive inflammatory cells in noninvolved psoriatic skin, and higher cortisol ratios to the presence of keratinocyte NK-1R immunoreactivity in involved skin. The degree of pruritus could not be correlated to the number of substance P positive fibers nor cells. Nonneuronal substance P and its receptor NK-1 might have a role in psoriasis, also during chronic stress.

Effect of matrine on the expression of substance P receptor and inflammatory cytokines production in human skin keratinocytes and fibroblasts

Matrine is a kind of alkaloid found in certain Sophora plants, which has been extensively used in China for the treatment of viral hepatitis, cancer, cardiac diseases and skin diseases (such as atopic dermatitis and eczema). It also has been confirmed that substance P (SP) and its receptor (neurokinin-1 receptor, NK-1R) are involved in the pathogenesis of inflammatory skin disorders. So the present study was designed to investigate the effect of matrine on the expression of NK-1R and cytokines production induced by SP in HaCaT cells (a human epidermal keratinocyte cell line) and dermal fibroblasts. In addition, cell viability was also evaluated. The results showed that matrine inhibited the expression of NK-1R in HaCaT cells and fibroblasts. SP induced the production of interleukin (IL)-1beta, IL-8, interferon (IFN)-gamma, and monocyte chemotactic protein (MCP)-1 in both cell types. Matrine 5-100 microg/mL had little effect on cell viability. It inhibited SP-induced IL-1beta, IL-8 and MCP-1 production in HaCaT cells and fibroblasts, while it increased the production of IFN-gamma in HaCaT cells. Both SP and matrine had no effect on the secretion of IL-6. These findings suggest that matrine may have potential treatment function on SP related cutaneous inflammation by inhibition of the expression of substance P receptor and regulation of the production of inflammatory cytokines.

Substance P receptor expression in human skin keratinocytes and fibroblasts

BACKGROUND

There is increasing evidence that neuropeptides, especially substance P (SP), may be involved in the pathogenesis of cutaneous allergic inflammation (CAI).

OBJECTIVES

To investigate expression of the SP receptor (neurokinin-1 receptor, NK-1R) in human epidermal keratinocytes and dermal fibroblasts and its potential influence in CAI.

METHODS

HaCaT cells (a human epidermal keratinocyte cell line) and dermal fibroblasts were cultured. The expression of NK-1R protein was examined by immunohistochemistry, and the mRNA level was detected by semiquantitative reverse transcriptase-polymerase chain reaction. The modulation of NK-1R expression in HaCaT cells and fibroblasts was detected by flow cytometry and Western blotting analysis.

RESULTS

NK-1R expression was found in HaCaT cells and fibroblasts. The expression of NK-1R mRNA in fibroblasts was weaker than in HaCaT cells. SP and interferon (IFN)-gamma significantly upregulated the expression of NK-1R. [d-Arg(1), d-Trp(7,9) Leu(11)]-SP (Spantide I), a panspecific NK-1R antagonist, reduced the expression of NK-1R stimulated by SP.

CONCLUSIONS

HaCaT cells and fibroblasts can express NK-1R at protein and transcription levels, and the expression was modulated by SP, IFN-gamma and Spantide I. This indicates that keratinocytes and fibroblasts are involved in the regulation of skin immunity and that NK-1R may play an important role in the pathogenesis of CAI.

[Importance of epidermal keratinocytes in itching]

Itch, a skin sensation that provokes a desire to scratch, is a common complaint. Severe itch accompanying various skin diseases such as atopic dermatitis is an important issue related to the quality of life. Although histamine from mast cells has been thought to play an essential role in itch, many severe pruritic diseases respond poorly to the H(1) histamine receptor antagonists. Therefore the precise mechanisms and mediators of itch in most pruritic diseases are unclear. To investigate the detailed mechanisms of the induction of itch, we have developed a mouse model. Studies using this model have demonstrated that keratinocytes play an important role in the induction of itch. The identification of keratinocyte stimulus factors and of products in keratinocytes could lead to developing new antipruritic medicines.

Neuroanatomy and neurophysiology of itch

The specific pathway of "pure," histaminergic itch is traced from the mechano-insensitive nerve fibers in the skin to their central cortical projections. Neuropathic itch created at different levels of this anatomical pathway is reviewed. In this review the present author discusses damage to pruritoceptors in the skin, entrapment syndromes, damage to spinal ganglia, nerve root impingement, injury of the spinal cord, and cerebral damage in the distribution of the middle cerebral artery, capsula interna, or thalamus. Itch in inflamed skin resulting from interactions between nerve transmitters and other mediators of inflammation is described.

Low Levels of Emotional Awareness Predict a Better Response to Dermatological Treatment in Patients with Psoriasis

BACKGROUND

Personality and emotional factors are thought to influence the onset of psoriasis, the occurrence of relapses, and the sensitivity of this condition to dermatological treatments.

OBJECTIVE

To explore the relationships between emotional disorders and emotional information processing in the one hand, and psoriasis severity and response to treatment on the other.

METHODS

We recruited 93 patients through an article in the local press. These patients attended three consultations. We evaluated psoriasis severity by Psoriasis Area and Severity Index (PASI) score and response to treatment by change in PASI score from baseline to the 3-month visit. We screened for comorbid mental disorders, using the Mini International Neuropsychiatric Interview. We used the Hospital Anxiety and Depression Scale to assess anxiety and depressive symptoms. Alexithymia (difficulty in identifying and expressing emotions) was evaluated with the 26-item version of the Toronto Alexithymia Scale (TAS-26) and the ability to integrate and differentiate emotions (emotional awareness) was assessed with the Lane and Schwartz Levels of Emotional Awareness Scale (LEAS).

RESULTS

Forty patients presented at least one psychiatric diagnosis and 33 were considered alexithymic (TAS > or =73). No psychological score was associated with baseline PASI score, which was higher in men and positively correlated with disease duration. Patients who considered their disease to be stress-reactive tended to have lower LEAS scores (p = 0.052). At the 3-month visit, PASI scores had significantly improved in the subset of patients (n = 67) presenting severe psoriasis at inclusion (PASI >2); emotional awareness and anxiety scores had also improved in these patients (p < 0.001), but dermatological and psychological changes were not statistically related. Dermatological improvement at 3 months with respect to baseline PASI was predicted by longer disease duration (>20 years) and lower baseline LEAS score (p = 0.044 and p = 0.021, respectively).

CONCLUSION

This study demonstrates the value of assessing the ability of patients with psoriasis to process emotional information, as defined by emotional awareness. Patients with low LEAS scores appear to be more reactive to stress, but also to be more responsive to treatment, suggesting the activation of a particular stress physiology by negative affective states that are not experienced.

Mobilisation of specific T cells from lymph nodes in contact sensitivity requires substance P

Capsaicin-mediated depletion of neuropeptides in the skin was previously shown to abolish a dinitrocholorobenzene (DNCB)-induced contact sensitivity (CS) response. To understand the basis for this disruption, we explored whether nerve fibres innervating the draining lymph node (LN) could be involved. As expected, removal of the draining LN after DNCB sensitisation abolished the CS response. Furthermore, the CS response could be abolished by destroying the nerve fibres in the draining LN and could be restored by providing the LN with the neuropeptide substance P. The size of the CS response restored by substance P was dose dependent. The response was also inhibited by exposing the lymph node to a neurokinin-1 receptor antagonist which blocks binding of substance P. The results suggest that an afferent signal from the skin via the sympathetic arm of the central nervous system evokes an efferent signal to the LN which combines to regulate the CS response. The efferent signal may serve to control or release from the LN primed effector lymphocytes into the circulation.

Cutaneous allergic contact dermatitis responses are diminished in mice deficient in neurokinin 1 receptors and augmented by neurokinin 2 receptor blockage

Sensory neuropeptides such as neurokinin A (NKA) or particularly substance P (SP) by neurokinin receptor (NK-R) activation modulate skin and immune cells functions during neurogenic inflammation. In this study, we examined the relative importance of SP/NK-1Rs or NKA/NK-2Rs in a murine model for allergic contact dermatitis (ACD) and tested if the functional absence of NK-Rs will impair inflammatory response in vivo. Mice lacking NK-1Rs (C57BL/6J-NK-1R-/-) displayed a significantly reduced ACD inflammatory ear swelling response to dinitrofluorobenzene (DNFB) with histological less edema and 50% fewer infiltrating leukocytes compared with the ACD response in wild-type (+/+) animals. In NK-1R+/+ mice, transient NK-1R inhibition impaired ACD sensitization. In vitro haptenized bone marrow-derived dendritic cells from NK-1R+/+ mice matured in the presence of an NK-1R antagonist displayed a reduced capability to induce T cell proliferation in vitro and ACD after adoptive transfer into naïve wild-type mice in vivo. By contrast, NK-2R inhibition significantly enhanced the ACD response in NK-1R null or in wild-type mice, whereas epicutaneous application of NK-2R agonists diminished the ACD inflammation. In conclusion, NK-1R and SP are required for antigen sensitization and a full inflammatory response to cutaneous allergens and NKA and the NK-2R mediate a contrasting anti-inflammatory role in ACD. Thus, SP, NKA, NK-1R, and NK-2R have important but differential roles in the regulation of cutaneous inflammatory responses.

Inhibitory effect of the repeated treatment with Unsei-in on substance P-induced itch-associated responses through the downregulation of the expression of NK(1) tachykinin receptor in mice

Unsei-in, a traditional medicine, is prescribed against pruritic cutaneous diseases, but the mechanisms of antipruritic action are still unknown. In the present study, we examined the antipruritic effects of Unsei-in in mice. Single administration of Unsei-in did not inhibit substance P-induced itch-associated response (scratching) in mice. However, repeated treatment with Unsei-in for 7 d significantly inhibited substance P-induced scratching. The same repeated treatment with Unsei-in suppressed the expression of NK(1) tachykinin receptors in the skin. These results suggest that Unsei-in inhibits substance P-associated itching and that the inhibition is at least partly due to the suppression of the expression of NK(1) tachykinin receptors in the skin.

Nerve outgrowth and neuropeptide expression during the remodeling of human burn wound scars. A 7-month follow-up study of 22 patients

Increasing data suggest that the skin nerve system is involved in wound healing. The objective of this study was to investigate the outgrowth of nerve fibers during the burn wound remodeling process and to analyze possible differences between normotrophic and hypertrophic burn wounds. In a prospective study, biopsies were taken from 22 patients with spontaneously healed partial-thickness burns at 1, 4 and 7-month post-burn. Nerve outgrowth and the expression of the neuropeptides substance P, neurokinin A, calcitonin gene-related peptide, vasoactive intestinal peptide and neuropeptide Y was monitored using immunohistochemistry. Our results showed that the number of nerve fibers gradually increased in both the dermis and the epidermis, but that they did not reach the levels of expression present in matched unburned skin of the same patient. A significantly higher number of nerve fibers were observed in normotrophic scars compared with hypertrophic scars. The number of neuropeptides-containing nerves in normotrophic and hypertrophic scars were similar.

IN CONCLUSION

7 months after wound closure, burn wound scars contain less nerve fibers than unburned skin. The significantly higher number of nerve fibers in normotrophic, compared with hypertrophic scars suggests a regulatory role for the skin nerve system in the outcome of burn wound healing.

Modulation of substance P and somatostatin receptors in cutaneous lymphocytic inflammatory and tumoral infiltrates

BACKGROUND

The expression of receptors for neuropeptides in the skin is modified in skin diseases.

OBJECTIVE

We studied the cutaneous expression of substance P (SP) and somatostatin (SOM) receptors (SPR and SSTR, respectively) in skin affected by cutaneous inflammatory or tumoral T-cell infiltrates because these two neuropeptides are the ones most involved in inflammation.

METHODS

We revealed expression of these receptors using a binding in situ technique that gave highly specific results. Skin biopsies were incubated with biotinylated neuropeptides (SP or SOM).

RESULTS

In normal skin, SSTR were observed on blood vessels, smooth muscle fibres and sweat glands. SSTR expression was modified only when expressed by keratinocytes in Ofuji papuloerythroderma and by plasmocytes in plasmocytoma. SPR distribution was not modified in subjects with atopic dermatitis or lupus. The expression of SPR in the epidermis was diminished in Ofuji papuloerythroderma and parapsoriasis and absent in mycosis fungoides.

CONCLUSIONS

These results suggest that malignant lymphocytic infiltrates can inhibit SPR expression on keratinocytes.