Langerhans' cells in hair follicles of the depigmenting C57Bl/Ler-vit.vit mouse. A model for human vitiligo

The C57Bl/Ler-vit.vit mouse grows a black pelage after birth. During successive hair molts, the fur loses its pigmentation. By 6 months of age, most of the fur of the animal is white. The epidermis of the ears and tail also loses its pigmentation. Histologic studies confirm that in the epidermis and hair follicles there is an absence of pigment cells identifiable by various histochemical or electron microscopic techniques. This mouse may be an excellent model in which to study the role of Langerhans' cells and the immune response in the pathogenesis of vitiligo, a study not easily done in humans. From results of prior studies, we postulated that if Langerhans' cells were involved in the destruction of melanocytes, they would be abnormal (either more or less numerous) in number during the active phase of depigmentation and normal in number after depigmentation was complete. To determine whether the Langerhans cell (Ia+/adenosine triphosphatase dendritic epidermal cell) might be involved in destruction of pigment cells, we quantified the number of Ia+ and adenosine triphosphatase dendritic cells in the hair follicles in skin from the ear, abdomen, back, and tail from male C57Bl/Ler-vit.vit mice while the fur and skin were depigmenting and after depigmentation was almost completed. We found that Langerhans' cells were normal in number during depigmentation and were most numerous after depigmentation. Previous studies indicate that Langerhans' cells in these mice are functionally defective and respond poorly to some contact allergens. From these morphologic and functional data, we conclude that Langerhans' cells probably are uninvolved in causing depigmentation in these mice. We also observed that the epithelium of hair follicles has a significantly higher (up to 1600/mm2) population density of Langerhans' cells than interfollicular skin.     

The in vivo melanocytotoxicity and depigmenting potency of N-2,4-acetoxyphenyl thioethyl acetamide in the skin and hair

Summary It has been shown previously that N-acetyl-4-S-cysteaminylphenol (N-Ac-4-S-CAP) is a tyrosinase Substrate and a potent depigmenting agent of dark skin and black hair. The present study evaluated the depigmenting potency of an acetyl derivative of N-Ac-4-S-CAP. N-2,4-acetoxyphenyl thioethyl acetamide (NAP-TKA) in the skin and hair. We tested for (i) in vitro metabolites in the skin after topical application. and (ii) in vivo depigmenting potency in the skin and hair. We found that NAPTEA was stable in water. but was converted to N-Ac-4-S-CAP after topical application to human skin. Therefore. although NAP-TEA was not a tyrosinase substrate. it could react with tyrosinase after being converted to N-Ac-4-S-CAP by 0-deacetylation in vivo. NAP-TEA produced marked depigmentation of dark skin (Yucatan pig) after daily topical application. When given by intraper-itoneal injection. it resulted in complete loss of hair colour (white) grown at the epilated site in adnlt C57 black mice after daily administration for l0 days, and incomplete loss of coat colour (silver grey) in newborn C57 black mice after a single administration, The depigmentation of the skin and hair was reversible, Splil-dopa preparalion and eieclron microsnipy indicated thal lliis depigmentation is primarily related to (i) a marked decrease in the number of functioning melanocytes and melanized melanosomes, (ii) a decrease in the number of melanosomes transferred to keratinocytes, and (iii) selective degeneration/inactivation of melanocytes. and deposition of melanin-like malerial in the Golgi cisternae. coated vesicles and melanosomes. where tyrosinase is reported to be located. We propose the NAP-TEA is converted in vivo to N-Ac-4-.S-CAP which. via interaction with tyrosinase. causes reversible depigmentation of the skin and hair.     

Oral zinc sulphate causes murine hair hypopigmentation and is a potent inhibitor of eumelanogenesis in vivo

BACKGROUND: C57BL/6 a/a mice have been widely used to study melanogenesis, including in electron paramagnetic resonance (EPR) studies. Zinc cations modulate melanogenesis, but the net effect of Zn2+ in vivo is unclear, as the reported effects of Zn2+ on melanogenesis are ambiguous: zinc inhibits tyrosinase and glutathione reductase in vitro, but also enhances the activity of dopachrome tautomerase (tyrosinase-related protein-2) and has agonistic effects on melanocortin receptor signalling. OBJECTIVES: To determine in a C57BL/6 a/a murine pilot study whether excess zinc ions inhibit, enhance or in any other way alter hair follicle melanogenesis in vivo, and to test the usefulness of EPR for this study. METHODS: ZnSO(4).7H2O was continuously administered orally to C57BL/6 a/a mice during spontaneous and depilation-induced hair follicle cycling (20 mg mL-1; in drinking water; mean+/-SD daily dose 1.2+/-0.53 mL), and hair pigmentation was examined macroscopically, by routine histology and by EPR. RESULTS: Oral zinc cations induced a bright brown lightening of new hair shafts produced during anagen, but without inducing an EPR-detectable switch from eumelanogenesis to phaeomelanogenesis. The total content of melanin in the skin and hair shafts during the subsequent telogen phase, i.e. after completion of a full hair cycle, was significantly reduced in Zn-treated mice (P=0.0005). Compared with controls, melanin granules in precortical hair matrix keratinocytes, hair bulb melanocytes and hair shafts of zinc-treated animals were reduced and poorly pigmented. Over the course of several hair cycles, lasting hair shaft depigmentation was seen during long-term exposure to high-dose oral Zn2+. CONCLUSIONS: High-dose oral Zn2+ is a potent downregulator of eumelanin content in murine hair shafts in vivo. The C57BL/6 mouse model offers an excellent tool for further dissecting the as yet unclear underlying molecular basis of this phenomenon, while EPR technology is well suited for the rapid, qualitative and quantitative monitoring of hair pigmentation changes.     

Mice transgenic for Kit(V620A): recapitulation of piebaldism but not progressive depigmentation seen in humans with this mutation

Piebaldism is an autosomal dominant genetic pigmentary disorder, characterized by congenital white hair and patches located on the forehead, anterior trunk, and extremities. Most piebald patients have a mutation of the KIT gene, which encodes a tyrosine kinase receptor involved in pigment cell development. The white hair and patches of such patients are already completely formed at birth and do not usually expand thereafter. This stability of pigmented spots also applies to Kit(W) and Kitl(Sl) mutant mice. However, two novel cases of piebaldism were reported in 2001, in which both mother and daughter having a novel Val620Ala mutation in their KIT gene showed progressive depigmentation. To prepare an animal model of this mutation, to explore undefined functions of KIT signaling for maintaining pigmented melanocytes in the skin or more specifically the integrity of the melanocyte stem cell system in the postnatal skin, we produced transgenic mice expressing Val620Ala Kit. These mice well mimicked the white spotting pattern of patients; however, no change in this pattern was observed after birth, even after increasing the transgene expression by various means. Here, we report the unexpectedly extremely stable maintenance of the melanocyte stem cell system under stringent conditions for KIT signaling.     

Hair depigmentation during chemotherapy with a class III/V receptor tyrosine kinase inhibitor

BACKGROUND: Hair pigmentation is regulated by several factors including the interaction of the ligand stem cell factor (SCF) with its class III receptor tyrosine kinase, c-kit. An interruption of SCF/c-kit signal transduction results in hair depigmentation. OBSERVATIONS: A 69-year-old white woman developed hair depigmentation and fine-textured hair while being treated with the phase I chemotherapeutic agent GW786034, a class III/V receptor tyrosine kinase inhibitor. Discontinuation of therapy resulted in a reversal of these hair changes. CONCLUSIONS: Treatment with oral GW786034 resulted in reversible hair depigmentation and change in hair growth rate and texture, which were most likely due to an incomplete inhibition of SCF/c-kit signaling, although the exact mechanism is unknown. It would be intriguing to investigate topical tyrosine kinase inhibitors as a treatment for unwanted body hair.     

Depigmented extramammary Paget's disease

BACKGROUND: Depigmented extramammary Paget's disease (EMPD) has been reported in a few cases. Depigmented macules or patches may be the only presenting sign or may coexist with the classical erythematous lesions. OBJECTIVES: To investigate the occurrence rate and clinical presentation of depigmentation in EMPD. METHODS: All pathology-proven cases of EMPD diagnosed in our department during 1990-2003 were retrieved. The clinical photographs were reviewed for evidence of local depigmentation. The pathological diagnosis of EMPD in the whitish lesions was confirmed by positive expression of cytokeratin 7 or carcinoembryonic antigen, and/or the presence of intracytoplasmic mucin. RESULTS: Of 19 cases of EMPD, six (30%) manifested depigmented lesions which were confirmed to be EMPD pathologically. In two patients, the hypopigmentation was associated with erythematous lesions at the initial presentation. In four others, the depigmentation developed later as local recurrence after excision, cryotherapy, photodynamic therapy or radiotherapy. The progressive enlargement of the depigmentation and the appearance of separate new white lesions in these four cases suggested that the localized depigmentation was unlikely to be simple postinflammatory hypopigmentation. CONCLUSIONS: Our study suggests that depigmented EMPD may not be rare. Localized depigmentation in the genital area can be an early sign of EMPD and its local recurrence. In patients with an established diagnosis of EMPD, appearance of new white lesions and continuous enlargement of depigmented patches should not be dismissed as simple treatment-induced postinflammatory hypopigmentation or another type of hypopigmented lesion without biopsy confirmation.     

Pigmented guinea pig skin irradiated with Q-switched ruby laser pulses. Morphologic and histologic findings

Q-switched ruby laser pulses cause selective damage to cutaneous pigmented cells. Repair of this selective damage has not been well described. Therefore, using epilated pigmented and albino guinea pig skin, we studied the acute injury and tissue repair caused by 40-ns, Q-switched ruby laser pulses. Gross observation and light and electron microscopy were performed. No specific changes were evident in the albino guinea pigs. In pigmented animals, with radiant exposures of 0.4 J/cm2 or greater, white spots confined to the 2.5-mm exposure sites developed immediately and faded over 20 minutes. Delayed depigmentation occurred at seven to ten days, followed by full repigmentation by four to eight weeks. Regrowing hairs in sites irradiated at and above 0.4 J/cm2 remained white for at least four months. Histologically, vacuolation of pigment-laden cells was seen immediately in the epidermis and the follicular epithelium at exposures of 0.3 J/cm2 and greater. Melanosomal disruption was seen immediately by electron microscopy at and above 0.3 J/cm2. Over the next seven days, epidermal necrosis was followed by regeneration of a depigmented epidermis. By four months, melanosomes and melanin pigmentation had returned; however, hair follicles remained depigmented and devoid of melanocytes. This study demonstrates that selective melanosomal disruption caused by Q-switched ruby laser pulses leads to transient cutaneous depigmentation and persistent follicular depigmentation. Potential exists for selective treatment of pigmented epidermal and dermal lesions with this modality.     

THE SELECTIVE DEPIGMENTING ACTION OF 8-HYDROXYQUINOLINE ON HAIR GROWTH IN THE MOUSE

Summary.— Topical applications of 8-hydroxyquinoiine to mouse skin cause depigmented hair to grow in patterns which change with time and appear to be closely associated with the hair growth cycles. Sufficiently frequent applications result in virtually complete depigmentation in young adult C57BL female mice, while single applications cause isolated bands of depigmented hair. Female mice are more sensitive than males, but some treated newborn mice were unaffected, 8-Hydroxyquinaldine has a similar action. Compounds not showing this effect include 2 recognized depigmenting agents, some compounds related to 8-hydroxyquinoline and some other analytical reagents for copper.     

Alterations in cutaneous immune reactivity to dinitrofluorobenzene in graying C57BL/vi.vi mice

The fur of the C57BL/vi.vi mouse is black at 6 weeks of age. By 6 months of age the animals are white and there are no identifiable pigment cells within the epidermis or hair bulbs. Human subjects with vitiligo exhibit loss of epidermal pigment cells. The loss of pigment cells in human subjects with vitiligo has been associated with loss of cutaneous immune reactivity to contact allergens. Therefore, studies were performed to determine whether loss of pigment cells in these depigmenting mice also was associated with loss of the cutaneous immune response. The number of Ia-positive (Ia +) Langerhans cells (LC)/mm2 on the back and the ear, the sites of sensitization and challenge with dinitrofluorobenzene (DNFB), was quantified before, during, and after depigmentation. We observed that there were fewer LC/mm2 on the back and the ear before and after pigment loss in the graying mice than in the normal control C57BL/6 mice. The young pigmented C57BL/vi.vi mice were capable of developing moderate contact hypersensitivity; the older depigmented mice did not sensitize to DNFB. We conclude that the depigmented mice, like human subjects with vitiligo, have a loss of contact hypersensitivity associated with a loss of pigment cells within the epidermis. In the mouse, loss of melanocytes is associated with a decrease in the population density of Ia + cells.     

Colorimetry provides a rapid objective measurement of de novo hair growth rate in mice

Background: Depilated mice have been used as a test platform for hair growth-regulating agents. However, currently available assessment tools for hair growth in mice are less than ideal.
Methods: Tristimulus colorimetry of the fur color of depilated agouti, albino, and black mice with L ^*, a ^*, and b ^* values were performed daily until the full growth of pelage. Using light-emitting diode (LED) irradiation (650 and 890 nm) with a daily dose of 3.5 J/cm² as hair growth regulators, the hair growth rates observed by the global assessment were compared with those derived from colorimetry.
Results: In contrast to a ^* and b ^* values, L ^* values changed more drastically over time in the anagen phase regardless of fur color. Unlike the inhibitory effect of 650 nm irradiation, LED of 890 nm promoted de novo hair regrowth in mice. The difference in hair growth rates detected by colorimetry paralleled the observation made by the global assessment.
Conclusion: The L ^* value of fur color obtained by tristimulus colorimetry was a sensitive yet quantitative indicator of de novo hair growth, and could be used to project the hair growth rate in mice.     

miR‐128‐1 is not required for hair pigmentation in mice

MicroRNAs are endogenous, regulatory RNAs implicated in many biological processes including pigmentation. Software algorithms and in vitro experiments predict that microRNAs can target pigmentation pathway genes, but few have been tested in vivo. MiR‐128‐1, a microRNA within the strongly selected lactase locus in the human genome, has predicted pigmentation targets. To test the role of miR‐128‐1 in pigment regulation, we created C57BL/6 agouti miR‐128‐1 knockout mice and quantified melanin deposition in hair. MiR‐128‐1 knockout mice have no detectable hair pigmentation phenotype. We conclude that miR‐128‐1 does not play a significant regulatory role in hair pigmentation in mice.     

Ultrastructural observations on the hair bulb melanocytes and melanosomes in acute alopecia areata

It is well recognized that alopecia areata (Aa) may preferentially affect pigmented hair and may spare white hair, and that regrowing hair in the disease is often initially white. In addition, there is an association with vitiligo and ocular depigmentation. To date, the pathomechanisms of the melanocyte effects are unclear. We have studied 10 patients with untreated acute alopecia areata, and three normal patients without hair loss. Morphologic changes, studied by conventional light and electron microscopy, in the cytoplasm of affected melanocytes often predated nuclear hyperchromatism. Increased numbers of bizarre melanosomes were found in affected melanocytes compared with normal ones; such melanosomes had incomplete or "aborted" melanization, resulting in poor pigment deposition, and were disrupted, enlarged and rounded, with loss of normal ellipsoidal shape. An unusual outer root sheath (ORS) distribution of hair bulb melanocytes was seen. Other atypical melanosome effects included marked pigment displacement into peribulbar and DP melanophages. In the DP clumped melanin granules formed giant spherical complexes without discernible limiting membranes, which were sometimes associated with lymphocytes. These morphologic changes indicate an active involvement of hair bulb melanocytes in alopecia areata.     

文眉致白癜风七例

【摘要】 目的 报道文眉所致白癜风7例。方法 收集2017年12月至2019年5月河南省人民医院皮肤科诊治的7例文眉引起的白癜风,回顾其临床特点。结果 7例患者文眉后1个月至1年出现数根眉毛变白,早期均表现为眉毛变白,眉部皮肤正常,眉周逐渐出现白斑,边界不清。眉部皮损反射式共聚焦扫描显微镜特征：基底层及毛囊周围色素缺失,真皮浅、中层可见高折光无定形物（色料）。斑贴试验：文眉色料均为阴性,十二醇硫酸钠均呈阳性。结论 文眉后引起的白癜风,早期眉部皮肤未见色素减退斑,结合眉部皮损反射式共聚焦扫描显微镜特征可减少误诊。     

Lymphocyte infiltration of the skin in transgenic mice carrying the human interleukin-2 gene

Inflammatory lesions of the skin such as erythema, depigmentation and hair loss were observed in C57/BL6(B6) transgenic mice that carried an intact human genomic interleukin-2 gene (gIL-2 transgenic mice). Accumulation of T lymphocytes in the perivascular and periadnexal areas of the dermis was the first change, followed by dermal papillary oedema, which occurred before the development of macroscopic skin lesions. In 3- or 4-week-old transgenic mice with slight erythema and depigmentation of the skin, there was an increase in the number of perivascular lymphocytes accompanied by the diffuse infiltration of neutrophils and monocytes in the damaged skin. These morphological skin changes were not observed in non-transgenic mice, which were bred together with transgenic litter mates. These findings suggest that lymphocyte infiltration of the perivascular space of the skin is a primary event of exogenously introduced human interleukin-2 gene, resulting in secondary cutaneous changes in gIL-2 transgenic mice.This work was presented in part at the 52nd Annual Meeting of the Society for Investigative Dermatology, Seattle, Wash., 1–3 May 1991     

Leptin of dermal adipose tissue is differentially expressed during the hair cycle and contributes to adipocyte‐mediated growth inhibition of anagen‐phase vibrissa hair

Adipose tissue encircles the lower portion of anagen hair follicles and may regulate hair cycle progression. As leptin is a major adipokine, its level of expression from the dermal white adipose tissue during hair cycle progression was studied. The result shows that leptin level is differentially expressed during hair cycle, the lowest in early anagen phase, upregulated in late anagen phase and the highest in the telogen phase. On the other hand, leptin receptor is detected in keratin 15‐positive hair bulge epithelium of both anagen‐ and telogen‐phase hair follicles of mice pelage and vibrissa hair, and hair from human scalp. Leptin contributes to adipocyte‐mediated growth inhibition of anagen‐phase vibrissa hair as demonstrated in organ culture and coculture system. Our data suggest that leptin of dermal white adipose tissue might regulate hair growth and, therefore, hair cycle progression via leptin receptor on the hair follicle epithelium.     

Characterization and quantification of wound‐induced hair follicle neogenesis using in vivo confocal scanning laser microscopy

Background: In vivo confocal scanning laser microscopy (CSLM) is a recently developed non‐invasive technique for visualizing microscopic structures with the skin. CSLM has been used to characterize proliferative and inflammatory skin diseases, neoplastic skin lesions and pigmented lesions. Objective: Here, we assessed the ability of CSLM to evaluate the formation of neogenic hair follicles after a full‐thickness wound in mice. Methods: Full‐thickness wounds were made on the dorsal skin of 3‐week‐old mice. After scab detachment (SD), the number, width, length, space and volume of neogenic hair follicles were analyzed using CSLM. The results were compared with those from conventional methods, including staining for alkaline phosphatase (AP) and keratin 17 (K17) as well as histology. Results: Quantification of neogenic hair follicles using CSLM compared favorably with the results from direct measurements on isolated epidermal tissue after immunostaining for K17, a marker for the epithelial portion of new hair follicles. CSLM detected 89% of K17‐stained follicles. CSLM more accurately quantified the number of new follicles compared with AP staining, which detects the dermal portion of the new follicle. The width and length measurement from CSLM and histology were very close and correlated with each other. The minimum length of a neogenic hair follicle that could be detected by CSLM was 21 μm. The space between neogenic hair follicles was decreased in histological sections compared with CSLM. Conclusion: CSLM is an accurate and valuable method for counting and measuring neogenic hair follicles non‐invasively. CSLM produces images similar to histology in mice. Measurements of microstructures using CSLM more accurately reflect actual sizes as this technique avoids fixation artifacts. In vivo visualization of developing follicles with CSLM allows the detection of serial changes in hair follicle formation, thus conserving the numbers of mice required for studies and improving the detection of temporal changes in developing hair follicles.