The occurrence of cutaneous nerve endings and neuropeptides in vitiligo vulgaris: a case-control study

From mice to men: An assessment of preclinical model systems for the study of vitiligo

Vitiligo is an autoimmune skin disease of multiple etiology, for which there is no complete cure. This chronic depigmentation is characterized by epidermal melanocyte loss, and causes disfigurement and significant psychosocial distress. Mouse models have been extensively employed to further our understanding of complex disease mechanisms in vitiligo, as well as to provide a preclinical platform for clinical interventional research on potential treatment strategies in humans. The current mouse models can be categorized into three groups: spontaneous mouse models, induced mouse models, and transgenic mice. Despite their limitations, these models allow us to understand the pathology processes of vitiligo at molecule, cell, tissue, organ, and system levels, and have been used to test prospective drugs. In this review, we comprehensively evaluate existing murine systems of vitiligo and elucidate their respective characteristics, aiming to offer a panorama for researchers to select the appropriate mouse models for their study.

Current Debates on Etiopathogenesis and Treatment Strategies for Vitiligo

Vitiligo is an acquired, chronic, and progressive depigmentation or hypopigmentation characterized by the destruction of melanocytes and the occurrence of white patches or macules in the skin, mucosal surface of eyes, and ears. Melanocytes are the melanin pigment-producing cells of the skin which are destroyed in pathological conditions called vitiligo. Approximately 0.5 - 2.0% of the population is suffering from vitiligo, and a higher prevalence rate of up to 8.8% has been reported in India. It is caused by various pathogenic factors like genetic predisposition, hyperimmune activation, increased oxidative stress, and alteration in neuropeptides level. Genetic research has revealed a multi- genetic inheritance that exhibits an overlap with other autoimmune disorders. However, melanocytes specific genes are also affected (such as DDR1, XBP1, NLRP1, PTPN22, COMT, FOXP3, ACE, APE, GSTP1, TLR, SOD, and CTLA-4). A number of therapeutic options are employed for the treatment of vitiligo. The topical corticosteroids and immunomodulators are currently in practice for the management of vitiligo. Phototherapies alone and in combinations with other approaches are used in those patients who do not respond to the topical treatment. The main focus of this review is on the etiopathological factors, pharmacological management (phototherapy, topical, systemic, and surgical therapy), and herbal drugs used to treat vitiligo.

The Efficacy and Psychoneuroimmunology Mechanism of Camouflage Combined With Psychotherapy in Vitiligo Treatment

Background and Objectives

The efficacy of camouflage combined with psychotherapy and the underlying mechanisms are poorly understood in vitiligo management. This study aimed to investigate the joint efficacy and further explore psycho-neuro-endocrine-immune-skin interactions.

Patients and Methods

In a prospective, non-randomized and concurrent controlled trial, patients were divided into two groups. Quality of life (QOL) was evaluated using the Chinese version of the Vitiligo Life Quality Index (VLQI-C). Serum levels of neuropeptides and cytokines were detected by enzyme-linked immunosorbent assay.

Results

A total of 149 patients were included for final evaluation. After treatment for 4 weeks, total and subcategory quality of life scores in the intervention group were much lower than in the control group. Serum levels of neuropeptide-Y (NPY) and melanin-concentrating hormone (MCH) significantly decreased, and serum level of adrenocorticotropic hormone (ACTH) increased in both active and stable patients of the intervention group, but not in the control group. In addition, the serum levels of interferon-γ (IFN-γ), CXC chemokine ligand 10 (CXCL10), and interleukin-1β (IL-1β) decreased in both the active and stable patients of the intervention group and only in the active patients of the control group.

Conclusions

The combination of camouflage and psychotherapy provided a clinically meaningful improvement in quality of life and ameliorated the outcome by likely modulating the psycho-neuro-endocrine-immuno-skin system during vitiligo management.

Clinical Trial Registration

www.clinicaltrials.gov/ct2/show/NCT03540966, identifier: NCT03540966.

Premature cell senescence in human skin: Dual face in chronic acquired pigmentary disorders

Although senescence was originally described as an in vitro acquired cellular characteristic, it was recently recognized that senescence is physiologically and pathologically involved in aging and age-related diseases in vivo. The definition of cellular senescence has expanded to include the growth arrest caused by various cellular stresses, including DNA damage, inadequate mitochondria function, activated oncogene or tumor suppressor genes and oxidative stress. While senescence in normal aging involves various tissues over time and contributes to a decline in tissue function even with healthy aging, disease-induced premature senescence may be restricted to one or a few organs triggering a prolonged and more intense rate of accumulation of senescent cells than in normal aging. Organ-specific high senescence rate could lead to chronic diseases, especially in post-mitotic rich tissue. Recently, two opposite acquired pathological conditions related to skin pigmentation were described to be associated with premature senescence: vitiligo and melasma. In both cases, it was demonstrated that pathological dysfunctions are not restricted to melanocytes, the cell type responsible for melanin production and transport to surrounding keratinocytes. Similar to physiological melanogenesis, dermal and epidermal cells contribute directly and indirectly to deregulate skin pigmentation as a result of complex intercellular communication. Thus, despite senescence usually being reported as a uniform phenotype sharing the expression of characteristic markers, skin senescence involving mainly the dermal compartment and its paracrine function could be associated with the disappearance of melanocytes in vitiligo lesions and with the exacerbated activity of melanocytes in the hyperpigmentation spots of melasma. This suggests that the difference may arise in melanocyte intrinsic differences and/or in highly defined microenvironment peculiarities poorly explored at the current state of the art. A similar dualistic phenotype has been attributed to intratumoral stromal cells as cancer-associated fibroblasts presenting a senescent-like phenotype which influence the behavior of neoplastic cells in either a tumor-promoting or tumor-inhibiting manner. Here, we present a framework dissecting senescent-related molecular alterations shared by vitiligo and melasma patients and we also discuss disease-specific differences representing new challenges for treatment.

The role of TrkA in the promoting wounding-healing effect of CD271 on epidermal stem cells

CD271, a receptor of nerve growth factor (NGF), affects the biological properties of epidermal stem cells (eSCs) which are essential for skin wound closure. Tropomyosin-receptor kinase A (TrkA), another receptor of NGF, combined with CD271 has been involved with nervous system and skin keratinocytes. However, the exact role of TrkA combined with CD271 in eSCs during skin wound closure is still unclear. This study aimed to reveal the role of TrkA in the promoting wounding-healing effect of CD271 on eSCs. We obtained CD271-vo (over-expression of CD271) eSCs by lentiviral infection. K252a was used to inhibit TrkA expression. Full-thickness skin mouse wound closure model (5 mm in diameter) was used to detect the ability of CD271 over-expressed/TrkA-deficient during wound healing. The biological characteristics of eSCs and their proliferation and apoptosis were detected using immunohistochemistry and western blot. The expressions of protein kinase B (pAkt)/Akt, phosphorylated extracellular-signal-related kinase (pERK)/ERK1/2, and c-Jun N-terminal kinase (pJNK)/JNK were also detected by western blot. We found that over-expression of CD271 promoted the biological functions of eSCs. Interestingly, over-expression of CD271 in the absence of TrkA neither promoted eSCs' migration and proliferation nor promoted wound healing in a mouse model. In addition, we observed the reduced expression of pAkt/Akt and pERK/ERK1/2 following TrkA inhibition in vitro. Our studies demonstrated that the role of TrkA in the promoting wounding-healing effect of CD271 on eSCs.

Focus on Vitiligo: A Generalized Skin Disorder

Vitiligo is an acquired pigmentation disorder due to a disappearance of functioning melanocytes from the epidermis and clinically characterized by achromic patches, often spreading over time. It is still not fully understood how melanocytes disappear in vivo, inducing these peculiar lesions. There are three major hypotheses for the pathogenesis of the disease: the autoimmune hypothesis considers that the disappearance of melanocytes is due to an autoimmune effector mechanism, the neural hypothesis suggests that an accumulation of neurochemical substances is able to damage epidermal melanocytes, and the metabolic hypothesis indicates that an increased sensitivity of melanocytes to oxidative stress is the crucial factor of the disease. Besides these well accepted hypotheses there are also some new interpretations based on a defective adhesion of melanocytic cells, an imbalance in the epidermal production of cytokines and an altered expression of melanocyte receptors. All these theories seem to be based on convincing evidence, indicating that they may contribute in variable proportions to the disease. There is also reasonable evidence at present that vitiligo potentially involves the whole integument, suggesting that it is a generalized skin disorder probably including different cell types during the active phase of the disease. It appears that the different theories may integrate with each other, supporting the concept that in vitiligo there is a final common step, i.e. a loss of pigment in the epidermis as well as different, possibly interacting, pathways leading up to this conclusive result.

The coexistence of peripheral nerve sheath tumors and vitiligo: more than coincidence?

Neurocristopathies arise from abnormal migration, differentiation, or proliferation of neural crest derivatives, leading to diverse clinical and pathological features. They are classified into dysgenetic or neoplastic, and can affect single or multiple sites (simple versus complex). Examples include congenital melanocytic nevi, neuroblastoma, Hirshsprung's disease, Waardenburg's syndrome, neurofibromatosis (NF) 1 and multiple endocrine neoplasia (MEN) 2A and 2B. We report two cases of peripheral nerve sheath tumors associated with vitiligo and discuss the possible implicated embryologic, genetic and molecular mechanisms. To our knowledge, we also report the first case of de novo malignant peripheral nerve sheath tumor (MPNST) associated with vitiligo.

Association of neuropeptide Y (NPY), interleukin-1B (IL1B) genetic variants and correlation of IL1B transcript levels with vitiligo susceptibility

BACKGROUND

Vitiligo is a depigmenting disorder resulting from loss of functional melanocytes in the skin. NPY plays an important role in induction of immune response by acting on a variety of immune cells. NPY synthesis and release is governed by IL1B. Moreover, genetic variability in IL1B is reported to be associated with elevated NPY levels.

OBJECTIVES

Aim of the present study was to explore NPY promoter -399T/C (rs16147) and exon2 +1128T/C (rs16139) polymorphisms as well as IL1B promoter -511C/T (rs16944) polymorphism and to correlate IL1B transcript levels with vitiligo.

METHODS

PCR-RFLP method was used to genotype NPY -399T/C SNP in 454 patients and 1226 controls; +1128T/C SNP in 575 patients and 1279 controls and IL1B -511C/T SNP in 448 patients and 785 controls from Gujarat. IL1B transcript levels in blood were also assessed in 105 controls and 95 patients using real-time PCR.

RESULTS

Genotype and allele frequencies for NPY -399T/C, +1128T/C and IL1B -511C/T SNPs differed significantly (p<0.0001, p<0.0001; p = 0.0161, p = 0.0035 and p<0.0001, p<0.0001) between patients and controls. 'TC' haplotype containing minor alleles of NPY polymorphisms was significantly higher in patients and increased the risk of vitiligo by 2.3 fold (p<0.0001). Transcript levels of IL1B were significantly higher, in patients compared to controls (p = 0.0029), in patients with active than stable vitiligo (p = 0.015), also in female patients than male patients (p = 0.026). Genotype-phenotype correlation showed moderate association of IL1B -511C/T polymorphism with higher IL1B transcript levels. Trend analysis revealed significant difference between patients and controls for IL1B transcript levels with respect to different genotypes.

CONCLUSION

Our results suggest that NPY -399T/C, +1128T/C and IL1B -511C/T polymorphisms are associated with vitiligo and IL1B -511C/T SNP influences its transcript levels leading to increased risk for vitiligo in Gujarat population. Up-regulation of IL1B transcript in patients advocates its possible role in autoimmune pathogenesis of vitiligo.

The epidermal Integrin beta-1 and p75NTR positive cells proliferating and migrating during wound healing produce various growth factors, while the expression of p75NTR is decreased in patients with chronic skin ulcers

BACKGROUND

More effective treatment strategies are needed for the chronic skin ulcers. Recently, it has been reported that clinical application of stem cells improve wound healing.

OBJECTIVE

We aimed to determine the dynamic time-course movement of epidermal stem cell markers especially p75 neurotrophin receptor (p75NTR) and Integrin beta-1 in wound healing process. Furthermore, we also investigated the presence of these markers in human.

METHODS

Epidermal Integrin beta-1(+) and p75NTR(+) cells were counted in wound healing process in mice. Both cells were also counted in human skin specimen obtained from chronic skin ulcers and healthy controls. Growth factor gene expression levels by purified mouse epidermal p75NTR(+) cells were also analyzed using real-time RT-PCR.

RESULTS

Integrin beta-1(+) and p75NTR(+) cells were proliferated from 3 days after wounding. Reepithelization was completed 7 days after wounding, and the numbers of cells were returned to the baseline levels by 14 days after wounding. Integrin beta-1(+) cells were proliferated in the basal layer, and p75NTR(+) cells were proliferated in the upper layer of epidermis. In human skin, Integrin beta-1(+) and p75NTR(+) cells were 81%±12% and 36%±15% of the basal cells, respectively. In patients with chronic skin ulcers, the percentage of Integrin beta-1(+) cells in the epidermis was identical to healthy controls. Surprisingly, p75NTR(+) cells were significantly decreased in chronic skin ulcer patients (1.2%±2.6%; p<0.0005) compared to healthy controls. Purified mouse epidermal p75NTR(+) cells expressed higher transforming growth factor-beta2 and vascular endothelial growth factor-alpha transcripts and lower epidermal growth factor transcripts than p75NTR(-) cells.

CONCLUSION

These results suggest that Integrin beta-1(+) and p75NTR(+) cells play an important role in wound healing process, and that p75NTR may be a key molecule and a candidate for new therapeutic target besides preexisting molecules for chronic skin ulcer patients.

The pathogenesis of vitiligo

BACKGROUND

Vitiligo is a commonly encountered pigmentary disorder. Numerous studies and investigations from all over the world have attempted to determine the mechanisms behind this disease; however, the pathogenesis of vitiligo remains elusive.

OBJECTIVE

n this comprehensive review article, we present the findings behind the five overarching theories of what causes this disfiguring and psychologically debilitating disease.

METHOD

We begin our discussion with the role of genetic predisposition and move onward to the neural theory first proposed in the 1950s. Next we discuss the autoimmune hypothesis, followed by the reactive oxygen species model, and conclude by describing the findings of the more recent melanocytorrhagy hypothesis.

CONCLUSION

Although the exact pathogenesis of vitiligo is uncertain, each of these theories likely plays a role. Understanding each theory would pave the way for therapeutic advances for this disease.

Potential role of neurogenic inflammatory factors in the pathogenesis of vitiligo

BACKGROUND

Vitiligo is a highly complex multifactorial condition of the skin that has an unclear mechanism of pathogenesis.

OBJECTIVE

This review summarizes the role of various neurogenic inflammatory factors significantly upregulated in vitiligo.

METHODS

A literature review was conducted of all pertinent data regarding neuropeptides that are altered in vitiligo and their possible role in the destruction of melanocytes.

RESULTS

The close associations between the skin, immune system, and nervous system, along with specific changes demonstrated in vitiligo patients, support a pathogenic mechanism of vitiligo that involves neuroimmunologic factors, the release of which can be governed by mental stress.

CONCLUSION

Neuropeptides and nerve growth factors are critical regulators of emotional response and may precipitate the onset and development of vitiligo in certain predisposed individuals. More studies are required to investigate whether a direct link exists between genetics, mental stress, and neurogenic factors in vitiligo.

Understanding mechanisms of vitiligo development in Smyth line of chickens by transcriptomic microarray analysis of evolving autoimmune lesions

Background

The Smyth line (SL) of chicken is an excellent avian model for human autoimmune vitiligo. The etiology of vitiligo is complicated and far from clear. In order to better understand critical components leading to vitiligo development, cDNA microarray technology was used to compare gene expression profiles in the target tissue (the growing feather) of SL chickens at different vitiligo (SLV) states.

Results

Compared to the reference sample, which was from Brown line chickens (the parental control), 395, 522, 524 and 526 out of the 44 k genes were differentially expressed (DE) (P ≤ 0.05) in feather samples collected from SL chickens that never developed SLV (NV), from SLV chickens prior to SLV onset (EV), during active loss of pigmentation (AV), and after complete loss of melanocytes (CV). Comparisons of gene expression levels within SL samples (NV, EV, AV and CV) revealed 206 DE genes, which could be categorized into immune system-, melanocyte-, stress-, and apoptosis-related genes based on the biological functions of their corresponding proteins. The autoimmune nature of SLV was supported by predominant presence of immune system related DE genes and their remarkably elevated expression in AV samples compared to NV, EV and/or CV samples. Melanocyte loss was confirmed by decreased expression of genes for melanocyte related proteins in AV and CV samples compared to NV and EV samples. In addition, SLV development was also accompanied by altered expression of genes associated with disturbed redox status and apoptosis. Ingenuity Pathway Analysis of DE genes provided functional interpretations involving but not limited to innate and adaptive immune response, oxidative stress and cell death.

Conclusions

The microarray results provided comprehensive information at the transcriptome level supporting the multifactorial etiology of vitiligo, where together with apparent inflammatory/innate immune activity and oxidative stress, the adaptive immune response plays a predominant role in melanocyte loss.

Investigating factors associated with depression of vitiligo patients in Singapore

AIMS

To explore the depression level of a group of vitiligo patients in Singapore and to identify factors associated with depression.

BACKGROUND

Unlike most internal illness, skin disease is often immediately visible to others and therefore people suffers from dermatological conditions may suffer psychological consequences.

DESIGN

A descriptive survey was conducted during the period October 2009-August 2010 in Singapore; 145 vitiligo patients aged 21+  completed a structured questionnaire.

METHODS

Three main outcome variables were employed in the study: demographic characteristics, clinical and psychosocial outcomes.

RESULTS

Among the patients, 17·2% (n = 25) had been identified as depressed. Multiple logistic regression analyses were used to identify a model to predict vitiligo patients who will have depression. The results showed that females (p = 0·05), aged below 50 years old (p = 0·016), having 5+ years of illness (p = 0·021) and with low self-esteem (p = 0·002) and poor quality of life scores (p = 0·004) were significant risk factors for depression.

CONCLUSION

Providing a suitable health care consultation for vitiligo patients may reduces depressive symptoms and maintaining their psychological health may be crucial for preventing suffering from depressive symptoms. Apart from the findings, these conclusions resonate with recent Singapore guidance on managing depression in vitiligo patients. This stresses the importance of prevention, early detection and stepped care with a multifaceted approach to management.

RELEVANCE TO CLINICAL PRACTICE

It is important to regularly screen for depressive symptoms among vitiligo patients. Focusing on vitiligo patients with enhancing self-esteem and improving quality of life should help in both the prevention and recognition of onset of depression among vitiligo patients.

Effect of PUVA therapy on electrodermal activity parameters in vitiligo patients

Recent electrophysiological studies on autonomic dysfunction in vitiligo patients show an autonomic dysfunction as measured by absent sympathetic skin response (SSR). Nothing is known about the reversibility of these autonomic parameters with treatment. The present study examined how Electrodermal Activity (EDA) parameters were affected from vitiligo illness before PUVA therapy and whether any electrophysiological gains acquired from PUVA therapy would influence the progression of the condition itself. We studied in 14 healthy subjectS and 14 patients with generalized vitiligo before and after treatment. EDA was recorded with a skin conductance unit connected to a personal computer. Before treatment, skin conductance level (SCL) and habituation number (HN) was higher in vitiligo group than control groups. After treatment, SCL and HN were decreased nearly to normal value. Before and after treatment, prevalence of non-responsivity was higher in vitiligo group than controls.

CONCLUSION

The sympathetic nervous system might have a particular role in the pathogenesis of vitiligo. Thus, patients with vitiligo may have changes to EDA parameters that are reversible to great extent with PUVA therapy. EDA is a useful method of studying the autonomic dysfunction in humans.

New Treatment Modalities for Vitiligo

The development of effective treatment modalities for vitiligo is dependent on an understanding of the events leading to depigmentation. However, the exact pathogenesis of vitiligo is still mostly unknown. Abnormalities in both humoral and cell-mediated immunity have been documented in vitiligo patients and they present a basis for using immunomodulating agents, such as corticosteroids and macrolide immunomodulators, in the treatment of vitiligo. Macrolide immunomodulators, such as tacrolimus and pimecrolimus, which can be used topically, are known as topical immunomodulators (TIMs). TIMs inhibit the action of calcineurin, and consequently inhibit T-cell activation and the production of various cytokines; this is considered the working mechanism of action of TIMs in vitiligo. Several small studies and case reports on the use of TIMs in vitiligo have been published so far. Tacrolimus achieves better results on the face and neck than on other body areas. Particular advantages of TIMs are safety in treating these areas because of lack of skin atrophy and good tolerability. The incidence of application site adverse events in vitiligo seems to be lower than in the treatment of atopic dermatitis. On the face and neck, TIMs may become a useful tool in the treatment of adults and children with vitiligo despite possibly lower efficacy than topical corticosteroids. Further, larger, controlled clinical studies are warranted to determine the definite role of TIMs as monotherapy or in combination with other modalities in the treatment of vitiligo.

A critical appraisal of vitiligo etiologic theories. Is melanocyte loss a melanocytorrhagy?

Common generalized vitiligo is an acquired depigmenting disorder characterized by a chronic and progressive loss of melanocytes from the epidermis and follicular reservoir. However, the mechanism of melanocyte disappearance has never been clearly understood, and the intervention of cellular and humoral autoimmune phenomena as primary events remains unproven. In this review, is discussed the data supporting the major theories of vitiligo, namely melanocyte destruction (autoimmune, neural and impaired redox status) and melanocyte inhibition or defective adhesion. Based on recent morphologic findings in vivo supporting a chronic detachment and transepidermal loss of melanocytes in common generalized vitiligo, a new theory is suggested proposing melanocytorrhagy as the primary defect underlying melanocyte loss, integrating most of the possible triggering/precipitating/enhancing effects of other known factors.

Genetic association of the catalase gene (CAT) with vitiligo susceptibility

Vitiligo susceptibility is a complex genetic trait that may involve genes important for melanin biosynthesis, response to oxidative stress, and/or regulation of autoimmunity, as well as environmental factors. We report here case-control and family-based association studies for the catalase gene (CAT) in vitiligo patients. The CAT gene was selected as a candidate gene because of the reduction of catalase enzyme activity (EC 1.11.1.6) and concomitant accumulation of excess hydrogen peroxide observed in the entire epidermis of vitiligo patients. One of three CAT genetic markers studied was found to be informative for genotypic analysis of Caucasian vitiligo patients and control subjects. Both case/control and family-based genetic association studies of the T/C single nucleotide polymorphism (SNP) in exon 9 of the CAT gene, which is detectable with the restriction endonuclease BstX I, suggest possible association between the CAT gene and vitiligo susceptibility. The observations that T/C heterozygotes are more frequent among vitiligo patients than controls and that the C allele is transmitted more frequently to patients than controls suggest that linked mutations in or near the CAT gene might contribute to a quantitative deficiency of catalase activity in the epidermis and the accumulation of excess hydrogen peroxide (H2O2). The CAT gene may, therefore, be a susceptibility gene in some vitiligo patients, further supporting the epidermal oxidative stress model for vitiligo pathogenesis.

Vitiligo. Pathogenesis and treatment

Vitiligo is an acquired skin disorder caused by the disappearance of pigment cells from the epidermis that gives rise to well defined white patches which are often symmetrically distributed. The lack of melanin pigment makes the lesional skin more sensitive to sunburn. Vitiligo can be cosmetically disfiguring and it is a stigmatizing condition, leading to serious psychologic problems in daily life. It occurs worldwide in about 0.5% of the population and it occurs as frequently in males as it does in females. The cause is unknown, but might involve genetic factors, autoimmunity, neurologic factors, toxic metabolites, and lack of melanocyte growth factors. Since a causative (gene) treatment is not (yet) available, current modalities are directed towards stopping progression and to achieving repigmentation in order to repair the morphology and functional deficiencies of the depigmented skin areas. Many treatments have been used for some time; however; there are some new developments: narrowband ultraviolet (UV) B (311 nm) therapy, the combination of corticosteroid cream + UVA therapy, and the transplantation of autologous pigment cells in various modalities. In widespread vitiligo, residual pigment can be removed by depigmentation agents. Sunscreens, camouflage products, and good guidance may help the patient cope better with the disease.

Vitiligo-related neuropeptides in nerve fibers of the skin

Skin distribution of substance P (SP)-, somatostatin (SOM)-, calcitonin gene-related peptide (CGRP)- and neuropeptide Y (NPY)-like immunoreactivity (LI) in vitiligo patients was studied by an indirect immunofluorescence technique. Immunocytochemical characteristics of the epidermis, dermal-epidermal junction, papillary and reticular dermis and skin appendages were analyzed in lesional and marginal vitiligo areas, as well as in healthy skin. In healthy pigmented skin, SP-, SOM-, CGRP-, and NPY-LI nerve fibers were observed with specific distributional patterns. In uninvolved vitiligo skin, thin SP-containing fibers were evident in dermal papillae, extending into the epidermis, and SP-LI fibers were seen around blood vessels and sweat glands. SOM-LI varicose nerve fibers were associated with Meissner corpuscles in the dermal papillae, while CGRP-LI was demonstrated in the free subepidermal nerve terminals and in sensory nerve fibers around blood vessels, hair follicles and sweat glands. Autonomic NPY-nerve fibers innervated the eccrine sweat glands and blood vessels. The distribution of these neuropeptides in both marginal and lesional areas of vitiliginous skin was the same as in the skin of healthy control subjects, except for an increased immunoreactivity against NPY and, to a lesser extent, against CGRP in the skin depigmentation lesions. The elevated NPY levels in skin affected by vitiligo suggest that this peptide may serve as a neurochemical marker in the pathogenesis of the disease, thus supporting the neuronal theory of vitiligo.

Cutaneous blood flow and adrenoceptor response increase in segmental-type vitiligo lesions

It has been proposed that two types of vitiligo exist from the physiological and clinical points of view. Nonsegmental-type vitiligo is associated with autoimmune diseases while segmental-type vitiligo results from the dysfunction of sympathetic nerves in the affected area. Using laser Doppler flowmetry and iontophoresis for cutaneous microcirculatory assessments, we evaluated these two types of vitiligo in regard to their physiological changes. Ten patients with facial stable stage segmental-type vitiligo and ten stable nonsegmental-type vitiligo patients were selected for this study. Our results revealed that a nearly threefold increase in cutaneous blood flow was noticed in segmental-type vitiligo as compared to contralateral normal skin. In contrast, a 1.4-1.5 times difference was found among nonsegmental-type vitiligo, lesion side clinically normal skin and contralateral normal skin. There was a significant increase in cutaneous alpha- and beta-adrenoceptor response in segmental-type vitiligo lesions. However, no change in plasma catecholamines or adrenoceptor densities on blood cells was noticed. Our findings suggest that a dysfunction of the sympathetic nerves exists in the affected skin and plays a role in the pathogenesis of segmental-type vitiligo.

Neuropeptides and Langerhans cells

The immune system and nervous system are intimately related. In addition to neuroendocrine mechanisms, neuropeptides have a variety of effects on immune cells and are responsible at least in part for neurogenic inflammation. The presence of neuropeptides in the skin has been well documented. The influence of neuropeptides on Langerhans cells is the focus of this paper. The physical presence and effects of calcitonin gene-related peptide on Langerhans cells is emphasized. Discussion also includes the putative inflammatory and immunologic roles of vasoactive intestinal peptide, substance P, neurotensin, neuropeptide Y, and somatostatin in the skin.

Abnormal afferent nerve endings in the soft palatal mucosa of sleep apnoics and habitual snorers

Habitual snoring precedes obstructive sleep apnea (OSA), but the pathophysiological mechanisms behind progression are still unclear. The patency of upper airways depends on a reflexogen mechanism reacting on negative intrapharyngeal pressure at inspiration, probably mediated by mucosal receptors, i.e., via afferent nerve endings. Such nerves contain a specific nerve protein, protein-gene product 9.5 (PGP 9.5) and in some cases substance P (SP) and calcitonin gene-related (CGRP). Biopsies of the soft palatial mucosa were obtained from non-smoking men ten OSA patients, 11 habitual snorers and 11 non-snoring controls. The specimens were immunohistochemically analyzed for PGP 9.5, SP and CGRP. As compared to controls, an increased number of PGP-, SP- and CGRP-immunoreactive nerves were demonstrated in the mucosa in 9/10 OSA patients and 4/11 snorers, in addition to varicose nerve endings in the papillae and epithelium. Using double staining methodology, it could be shown that SP- and CGRP-like immunoreactivities (LIs) often coexisted in these fibres, as did CGRP- and PGP 9.5-LIs. The increased density in sensory nerve terminals are interpreted to indicate an afferent nerve lesion. Our results support the hypothesis of a progressive neurogenic lesion as a contributory factor to the collapse of upper airways during sleep in OSA patients.