Photoprotective effect of calcipotriol upon skin photoreaction to UVA and UVB

It has been shown that 1,25-dihydroxyvitamin D₃ has a photoprotective effect against UVB injury in mouse skin and cultured rat keratinocytes by induction of metallothionein (MT). Calcipotriol is a synthetic analogue of 1,25-dihydroxyvitamin D₃ with equipotent cell regulating properties, but with a lower risk of calcium-related side effects. The aim of the present study was to see whether calcipotriol has a photoprotective property both in vitro and in vivo. We examined the effect of calcipotriol on UV-induced damage of cultured human keratinocytes through a cell viability assay, and measurement of DNA synthesis by cultured keratinocytes, on UV-induced damage of mouse skin and on minimal erythema dose (MED). We found that calcipotriol was protective against UVB-induced reduction in DNA synthetic activity of cultured keratinocytes in relatively low doses (20 and 40 mJ/cm²) of UVB. With phototesting following application of calcipotriol, five subjects among 10 healthy volunteers and three among six psoriasis patients showed an increase in MED compared with the vehicle-treated site. These findings imply that calcipotriol may be photoprotective and that more extensive studies with various doses of UV irradiation and modes of calcipotriol delivery are required.     

Effectiveness and safety of topical calcipotriol in the treatment of flat seborrheic keratosis on the face

Seborrheic keratosis is the most common slow-growing, benign epithelial tumour, usually appearing on sun-exposed areas. Treatment modalities for seborrheic keratosis may be uncomfortable and/or time-consuming. We present a case series of 12 patients with solitary seborrheic keratosis localized on the face treated with 0.005% calcipotriol ointment. The treatment lasted 3–8 months and resulted in complete regression of the lesions. Remission (follow-up period) lasted from 6 to 10 years. We conclude that topical calcipotriol may be a useful treatment option for seborrheic keratosis.     

Comparison of the efficacy of calcipotriol and maxacalcitol in combination with narrow-band ultraviolet B therapy for the treatment of psoriasis vulgaris

BACKGROUND: Combination treatment with topical vitamin D(3) and narrow-band ultraviolet B (UVB) radiation is effective against psoriasis vulgaris. We compared the efficacy of the topical vitamin D(3) derivatives calcipotriol and maxacalcitol in combination therapy. MATERIALS AND METHODS: In this retrospective observational study, 21 patients admitted to Nagoya City University Hospital between April 2001 and September 2004 were enrolled. RESULTS: Combination treatment with calcipotriol or maxacalcitol and narrow-band UVB was effective against psoriasis vulgaris. Calcipotriol induced a more rapid improvement and required lower levels of narrow-band UVB irradiation to be effective. Serum calcium levels were slightly increased after 4 weeks of treatment, but there was no significant difference between the two groups. No other adverse effects were observed in either of the two groups. CONCLUSION: The findings of this retrospective observational study indicated that combination treatment with topical vitamin D(3) derivatives and narrow-band UVB is effective against psoriasis without any obvious side-effects. These findings provide further evidence that calcipotriol has advantages over maxacalcitol regarding the narrow-band UVB-accumulated treatment dose and improvement rate of psoriasis area and severity index (PASI) scores.     

Trichilemmal cyst: report of a case in which the cyst was connected with the epidermis by an epidermal canal.

An 87-year-old Japanese woman with a trichilemmal cyst (TC) on the subnasal area is described. Histopathological examination revealed that the cyst was connected with the overlying epidermis by an epidermal canal. This has suggested that the pathogenesis of TCs could be that they originate from the isthmus or lower portion of the hair follicle.     

Vitamin D and the skin

Vitamin D was originally discovered as a factor that regulates calcium and bone metabolism. Recent advances in investigation have shown that vitamin D also functions as a regulator of cellular growth and differentiation in various tissues. The skin is not an exception from such effects of vitamin D; it is regarded as a site of its activation and action. Evidence has accumulated showing that the active form of vitamin D and its analogs suppress growth and stimulate the terminal differentiation of keratinocytes. In psoriatic lesions, epidermal keratinocytes exhibit hyper-proliferation and impaired differentiation triggered by inflammation. Therefore, it is quite reasonable that vitamin D is effective on psoriasis. Indeed, within the past decade, analogs of vitamin D3 have been used as topical therapy for psoriasis. In this review, we summarize the fundamental features of vitamin D and the development of vitamin D therapy for psoriasis. Clinical application to other skin diseases and the future of vitamin D therapy in dermatology are also discussed.     

Effect of 1,24R-dihydroxyvitamin D3 on the growth of human keratinocytes

The effect of 1,24R-dihydroxyvitamin D3 (1,24R(OH)2D3), a synthetic analogue of a biologically active form of vitamin D3 (1,25-dihydroxyvitamin D3, 1,25(OH)2D3), on the growth of human keratinocytes cultured in serum-free medium was investigated. The growth of cultured normal human keratinocytes was inhibited by 65% by 10(-8)M 1,24R(OH)2D3 and by 90% by 10(-7)M 1,24(OH)2D3. It inhibited cell growth almost completely at 10(-6)M. The DNA synthesis of keratinocytes was also inhibited with 1,24R(OH)2D3 by 27% at 10(-8)M, 59% at 10(-7)M, and 92% at 10(-6)M. The inhibition of cell growth and DNA synthesis were more remarkable by 1,24R(OH)2D3 than by 1,25(OH)2D3. 1,24R(OH)2D3 also inhibited the growth of keratinocytes derived from patients with psoriasis vulgaris; the growth inhibitory effect was again more remarkable with 1,24R(OH)2D3 than with 1,25(OH)2D3. The viability and protein synthesis of keratinocytes were not affected by 1,24R(OH)2D3, suggesting that the growth inhibitory effect is due to its biological activity, not to cytotoxicity. The binding of [3H]-labeled 1,25(OH)2D3 to its receptor in the cytosolic fraction of cultured keratinocytes was competitively substituted by unlabeled 1,24R(OH)2D3 as well as 1,25(OH)2D3, suggesting that 1,24R(OH)2D3 binds to the 1,25(OH)2D3 receptor. It was found that the affinity of 1,24R(OH)2D3 for the receptor was slightly higher than that of 1,25(OH)2D3. These results demonstrate that 1,24R(OH)2D3 functions as a potent growth inhibitor in vitro in human keratinocytes from both normal and psoriatic epidermis, and it possesses a higher affinity for the 1,25(OH)2D3 receptor in cultured human keratinocytes. The difference in affinity of 1,24R(OH)2D3 for the 1,25(OH)2D3 receptor correlates with its greater inhibition of keratinocyte growth than 1,25(OH)2D3. 1,24R(OH)2D3 may be useful in the treatment of psoriasis.     

Skin colour and vitamin D: An update

Homo sapiens evolved in East Africa and had dark skin, hair, and eyes, in order to protect against deleterious consequences of intensive UV radiation at equatorial latitudes. Intensive skin pigmentation was thought to bear the risk of inefficient vitamin D₃ synthesis in the skin. This initiated the hypothesis that within the past 75 000 years, in which humans migrated to higher latitudes in Asia and Europe, the need for vitamin D₃ synthesis served as an evolutionary driver for skin lightening. In this review, we summarize the recent archeogenomic reconstruction of population admixture in Europe and demonstrate that skin lightening happened as late as 5000 years ago through immigration of lighter pigmented populations from western Anatolia and the Russian steppe but not primarily via evolutionary pressure for vitamin D₃ synthesis. We show that variations in genes encoding for proteins being responsible for the transport, metabolism and signalling of vitamin D provide alternative mechanisms of adaptation to a life in northern latitudes without suffering from consequences of vitamin D deficiency. This includes hypotheses explaining differences in the vitamin D status and response index of European populations.     

Efficacy and safety of topical calcipotriol in management of alopecia areata: A pilot study

Reports have highlighted serum vitamin D deficiency and reduced 1,25‐dihydroxyvitamin D(3) receptors(VDR) expression on hair follicles of alopecia areata(AA) patients. Very few studies have demonstrated efficacy of topical calcipotriol (vitamin D analogue) in AA. We intended to study the efficacy of calcipotriol lotion 0.005% in AA and correlate its outcome with serum vitamin D levels. We conducted a prospective study, in which 22 patients with AA were treated with calcipotriol lotion 0.005% twice daily for 3 months. Clinico‐epidemiological parameters including severity of AA and SALT score were calculated at baseline and at 12 weeks. Hair regrowth was assessed monthly at 4, 8, 12 weeks. Serum vitamin D levels were measured at baseline. After 12 weeks of treatment, hair regrowth was observed in 13 (59.1%) patients. Mean period for onset of disease stabilization and hair regrowth was 4 weeks and 4.21± 2.13 weeks, respectively. Among these 13 patients, SALT₅₀ and SALT₁₀₀ was observed in 6(46.2%) and 2(9%) patients, respectively. Response to treatment was better in patients with lower vitamin D levels (p < .009). Topical calcipotriol can be an alternative treatment in AA and it could prove to be more useful in patients who are vitamin D deficient.     

拉坦前列素对人头皮毛囊毛发生长的影响

目的:研究拉坦前列素对人头皮毛囊毛发生长状况变化的影响。方法:选取体外培养成功的毛囊120根,随机分为6组:空白对照组、试验组四组(分别加0.005%、0.001%、0.0005%、0.01%拉坦前列素)、阳性对照组(加米诺地尔125μg/mL)每组20根,培养14天。以显微镜目镜测微器测量毛囊长度。每组选取6根毛囊,掺入3H-TdR后,置于闪烁杯中液闪记数。结果:0.005%和0.001%拉坦前列素组毛囊毛发生长速度较其它组快,0.01%拉坦前列素组较其它组慢,差异有统计学意义;同位素3H-TdR摄入率值的比较结果与毛囊生长长度一致。结论:拉坦前列素对人头皮毛囊毛发生长的作用取决于药物浓度(低浓度起促进作用,高浓度起抑制作用);可能的机制为促进毛囊生长,抑制毛囊进入休止期。     

Histopathology of aging of the hair follicle

Hair follicles experience several changes with aging, the most noticeable of which is graying of the hair shaft due to loss of melanin. Additional changes in the diameter and length of the hair have contributed to the concept of senescent alopecia, which is different from androgenetic alopecia according to most. Graying happens in most individuals, although in different grades and starting at different ages. It is related to a decrease in the number and activity of the melanocytes of the hair bulb, which eventually completely disappear from the bulb of the white hair. Residual non‐active melanocytes remain in the outer root sheath and in the bulge, which allows for repigmentation of the hair under certain stimuli or conditions.     

Proliferating Activity of the Hair Follicular Melanocytes at the Early and Anagen III Stages in the Hair Growth Cycle: Detection by Immunocytochemistry for Bromodeoxyuridine Combined with DOPA Reaction Cytochemistry

In order to demonstrate the existence of proliferating activity in hair follicular melanocytes during the early and anagen III stages, immunocytochemistry for bromodeoxyuridine (BrdU) incorporated in the nuclei of the melanocytes for 1 hr was undertaken at the light and electron microscopic levels in combination with DOPA reaction cytochemistry. Light microscopically, about 30% of the nuclei of the DOPA reaction positive melanocytes at the anagen III stage of the hair growth cycle were labeled by anti-BrdU antibody. These melanocytes were observed in about one hundred hair follicles. Electron microscopically, the nuclei of a few undifferentiated melanocytes at the anagen II stage were labeled by anti-BrdU antibody-affiliated secondary antibody-gold particles. At the anagen III stage, localization of the immunogold particles in the DNA replication domains of the nuclei of the undifferentiated and redifferentiating melanocytes covered the patterns of the early, middle, and late S-phase. These findings suggest that the hair follicular melanocytes begin proliferation at the anagen II stage and that the melanocytes proliferate actively at the anagen III stage to repopulate the hair matrix during subsequent hair growth.     

Vitamin D receptor gene polymorphisms are associated with psoriasis susceptibility and the clinical response to calcipotriol in psoriatic patients

Psoriasis is a common genetic disease characterized by hyperproliferation and disordered maturation of keratinocytes. To date, many association studies between psoriasis and VDR gene have been conducted, but the results are controversial. Furthermore, vitamin D₃ analogue has anti-psoriatic activity; however, the clinical response is variable. This study was conducted to explore whether VDR gene polymorphisms are associated with psoriasis susceptibility and clinical response to calcipotriol in psoriatic patients. A total of 110 patients and 183 controls were genotyped for VDR gene polymorphisms rs2228570, rs731236, rs1544410 and rs7975232 by LDR method. SNP-based and haplotype-based association analyses were subsequently performed. Patients with PASI < 3 were treated with calcipotriol ointment monotherapy. After 6 weeks of therapy, the correlations between efficacy and the genotypes of each polymorphism were evaluated. The results showed that for rs7975232, allele A was significantly over-represented in psoriasis patients relative to controls (39.09% vs. 27.05%, OR (95% CI) = 1.731 (1.213-2.471)), and compared with the reference CC genotype, the following ORs were observed: AA genotype OR = 2.404 (95% CI: 1.085-5.328; P = .034) and GA genotype OR = 2.143 (95% CI: 1.283-3.579; P = .005). Haplotype analyses showed that the rs2228570/rs731236/rs1544410/rs7975232 CTGA was significantly over-represented in psoriasis patients compared with controls (OR (95% CI)=1.907 (1.132-3.214); P = .020). Among the patients with PASI < 3, the response rates to calcipotriol were significantly higher in patients with rs7975232 CC genotypes than in those with other genotypes (x² = 9.172, P = .010). These data suggest that VDR polymorphisms are associated with psoriasis susceptibility and clinical response to calcipotriol in psoriatic patients.     

All-trans retinoic acid inhibits binding of 1,25-dihydroxy-vitamin D3 to the vitamin D receptor in cultured human keratinocytes

Abstract Psoriasis is characterized by hyperproliferation and impared differentiation of epidermal keratinocytes (KCs). Psoriasis can be treated with derivatives of relinoic acid (RA) and vitamin D₃. Analogues of vitamin D₃ are able to inhibit proliferation and stimulate differentiation of KCs. In contrast, RA inhibits terminal differentiation of KCs. Interactions are known to occur between RA and vitamin D₃ signalling pathways. The purpose of the present study was to determine the effect of all-trans RA on the binding of 1,25-dihydroxy-vitamin D₃ (1,25 (OH)₂D₃) to the vitamin D₃, receptor (VDR) of cultured human KCs. Cultured KCs from normal adults were incubated with or without RA (10^?9–10^?7 M) for 4-24 h. Cells were then harvested, homogenized and ultrasonicated. The extracted protein was incubated with 3H-1,25 (OH)₂D₃ (0.015-1.0 nM) with or without 250-fold excess nonradioactive 1,25 (OH)₂D₃ for 24 h and specific binding was determined by use of the dextran coated charcoal binding assay. Western blot analysis utilizing the monoclonal antibody 9A7γ to VDR was performed on protein extracted from the KCs. The bands resulting from Western blot analysis were visualized by enhanced chemiluminescence. From Scatchard analysis it was found that KCs bind 1,25 (OH)₂D₃ with high affinity (Kd = 0.175 nM). This binding was dose and time dependently inhibited by RA (60% inhibition at 10^?7 M after 24 h of incubation). By Western blot analysis, RA had no effect on the amount of protein extracted from KCs at any of the RA concentrations tested. In conclusion, these results show that binding of vitamin D₃ to its receptor of human KCs can be inhibited markedly by RA without effecting the amount of protein. These results are in contrast to results with other cell types in which RA upregulates binding of 1,25 (OH)₂D₃ to the VDR. Because interaction between retinoids and vitamin D₃ may occur at different levels during signal trans-duction, it is not possible to predict from our results whether RA will inhibit the effects of vitamin D₃, in vivo.     

Mammalian target of rapamycin complex 1 (mTORC1) may modulate the timing of anagen entry in mouse hair follicles

Mammalian target of rapamycin (mTOR) is a central regulator of cell proliferation and survival. There is limited evidence that mTOR influences hair follicles (HFs), which undergo cycles of quiescence (telogen), growth (anagen) and regression (catagen). We sought to investigate whether mTOR, in particular mTOR complex 1 (mTORC1), regulates the hair growth cycle by employing biochemical, immunohistochemical and functional approaches in vivo. Here, we demonstrate that quantitative analysis of mTORC1 kinase activity shows phase‐dependent changes, and phosphorylated mTOR at S2448 (p‐mTOR) was localized in certain sites of HFs in a phase‐dependent manner. These results were indicative of mTOR's role in hair growth initiation. Finally, in a pharmacological challenge in vivo using the specific mTORC1 inhibitor, rapamycin, hair cycle initiation was delayed, suggesting a functional relevance of mTORC1 in anagen entry. Based on our findings, we propose that mTORC1 may participate in hair cycle regulation, namely the timing of anagen initiation.     

Comparative evaluation of the efficacy of topical tacrolimus 0.03% and topical calcipotriol 0.005% mixed with betamethasone dipropionate versus topical clobetasol 0.05% in treatment of alopecia areata: A clinical and trichoscopic study

Background

Alopecia areata (AA) is a common non-scarring hair loss disorder that affects children and adults with a great psychological burden because of its recurrent and sometimes treatment-refractory nature.

Objective

To compare the efficacy of topical calcineurin inhibitor, topical potent steroid combined with vitamin D analogue versus topical superpotent steroid in treatment of localized AA.

Patients and Methods

Sixty subjects with chronic (>1 year) localized (SALT score < 25%) AA, confirmed clinically and dermoscopically, were randomized into three groups. Group I used topical 0.03% tacrolimus (Tarolimus®), group II used topical potent steroid combined with vitamin D analogue (Daivobet®). and group III used topical superpotent steroid (Dermovate®). All patients continued a daily therapy for three successive months and were followed up for three other months. Assessment was done using PULL test, SALT score, and dermoscopic comparison before and after therapy.

Results

Group II showed comparable statistical results to group III with lower values in a non-statistically significant way. Group I achieved the least improvement among all groups.

Conclusion

Combined vitamin D analogues with potent steroid appears to be a more convenient treatment for localized AA than superpotent steroids because of less side effects and comparable efficacy. Tacrolimus needs further research or formula customization to be used as a topical therapy for AA.     

Patterning skin by planar cell polarity: the multi-talented hair designer

In mammals, the skin can form complex global and local patterns to meet diverse functional requirements in different parts of the body. To date, the fundamental principles that underlie skin patterning remain poorly understood because of the involvement of multiple interacting processes. Genes involved in the planar cell polarity (PCP) signalling pathway, which is capable of polarizing cells within the planar plane of an epithelium, can control the orientation and differentiation of hair follicles, underlining their involvement in skin pattern formation. Here, we summarize recent progress that has been made to understand the PCP signalling pathway and its function in mammalian skin, including its role in hair follicle morphogenesis, ciliogenesis and wound healing. We argue that dissecting PCP signalling in the context of hair follicle formation might reveal many as-yet-undiscovered functions for PCP in the development, homeostasis and regeneration of skin.