Time filter

Source Type

München, Germany

Gaspar E.,University of Lubeck | Nguyen-Thi K.T.,University of Lubeck | Hardenbicker C.,University of Lubeck | Tiede S.,University of Lubeck | And 8 more authors.
Journal of Investigative Dermatology | Year: 2011

In amphibians, thyrotropin-releasing hormone (TRH) stimulates skin melanophores by inducing secretion of α-melanocyte-stimulating hormone in the pituitary gland. However, it is unknown whether this tripeptide neurohormone exerts any direct effects on pigment cells, namely, on human melanocytes, under physiological conditions. Therefore, we have investigated whether TRH stimulates pigment production in organ-cultured human hair follicles (HFs), the epithelium of which expresses both TRH and its receptor, and/or in full-thickness human skin in situ. TRH stimulated melanin synthesis, tyrosinase transcription and activity, melanosome formation, melanocyte dendricity, gp100 immunoreactivity, and microphthalmia-associated transcription factor expression in human HFs in a pituitary gland-independent manner. TRH also stimulated proliferation, gp100 expression, tyrosinase activity, and dendricity of isolated human HF melanocytes. However, intraepidermal melanogenesis was unaffected. As TRH upregulated the intrafollicular production of pituitary neurohormones (proopiomelanocortin transcription and ACTH immunoreactivity) and as agouti-signaling protein counteracted TRH-induced HF pigmentation, these pigmentary TRH effects may be mediated in part by locally generated melanocortins and/or by MC-1 signaling. Our study introduces TRH as a novel, potent, selective, and evolutionarily highly conserved neuroendocrine factor controlling human pigmentation in situ. This physiologically relevant and melanocyte sub-population-specific neuroendocrine control of human pigmentation deserves clinical exploration, e.g., for preventing or reversing hair graying. © 2011 The Society for Investigative Dermatology.

Bodo E.,University of Lubeck | Bodo E.,College of Nyiregyhaza | Wiersma F.,University of Lubeck | Funk W.,Klinik Dr Koslowski | And 4 more authors.
Experimental Dermatology | Year: 2010

Erythropoietin (EPO) is now appreciated for not only drive erythopoiesis, but also to exert additional functions. Since we had previously shown that human hair follicles (HFs) are both an extra-renal source and an extra-medullary target of EPO, we have now studied whether one such function is the regulation of HF pigmentation. Human anagen VI HFs were treated with EPO (100 IU/ml) in serum-free organ culture. Unexpectedly, we noticed greatly divergent pigmentary effects of EPO, since both up- and down-regulation of HF melanin content and tyrosinase activity in situ was seen in HF derived from different individuals. These divergent effects could not be attributed to differences in skin regions, the total HF melanocyte number or specific traits of individual HF donors. Our pilot study provides first evidence suggesting that EPO may modulate normal human melanocyte functions under physiologically relevant conditions in situ. © 2009 John Wiley & Sons A/S.

Langan E.A.,University of Manchester | Ramot Y.,University of Lubeck | Ramot Y.,Hebrew University of Jerusalem | Hanning A.,University of Lubeck | And 7 more authors.
British Journal of Dermatology | Year: 2010

Background Human skin and scalp hair follicles are both a nonclassical target and an extrapituitary source of prolactin (PRL), which is a potent hair growth modulator. However, how the expression of PRL and PRL receptor (PRLR) is regulated in human skin is unknown. Objectives To investigate whether two key stimulators of pituitary PRL secretion, thyrotropin-releasing hormone (TRH) and oestrogen, also regulate cutaneous PRL and PRLR expression. Methods Female scalp skin and/or microdissected hair follicles were treated for 6 days in serum-free organ culture with oestrogen (100 nmol L-1), TRH (1-10 ng mL -1, 3-30 nm) or vehicle control. Quantitative immunohistomorphometry of skin and hair follicle sections was complemented with quantitative polymerase chain reaction for PRL and PRLR in cultured hair follicles and/or female human outer root sheath (ORS) keratinocytes. Results Oestrogen treatment significantly upregulated PRL and PRLR immunoreactivity in selected skin and hair follicle compartments, at the gene and protein level (P < 0·05). TRH significantly increased PRL immunoreactivity and transcription in hair follicles (P < 0·05); however, while it also increased PRLR transcription in hair follicles, it downregulated PRLR immunoreactivity in the hair follicle ORS (P < 0·05). Conclusions Our pilot study shows that two key endocrine controls of pituitary PRL secretion, oestrogen and TRH, also regulate PRL and PRLR expression in human skin. This provides novel insights into the regulation of extrapituitary PRL and PRLR expression, and invites exploration of oestrogen and TRH as novel therapeutic agents in the management of skin and hair diseases characterized by aberrant PRLR-mediated signalling. © 2010 British Association of Dermatologists.

Fischer T.W.,University of Lubeck | Herczeg-Lisztes E.,Debrecen University | Funk W.,Klinik Dr Koslowski | Zillikens D.,University of Lubeck | And 4 more authors.
British Journal of Dermatology | Year: 2014

Summary Background Caffeine reportedly counteracts the suppression of hair shaft production by testosterone in organ-cultured male human hair follicles (HFs).Objectives We aimed to investigate the impact of caffeine (i) on additional key hair growth parameters, (ii) on major hair growth regulatory factors and (iii) on male vs. female HFs in the presence of testosterone.Methods Microdissected male and female human scalp HFs were treated in serum-free organ culture for 120 h with testosterone alone (0·5 μg mL-1) or in combination with caffeine (0·005-0·0005%). The following effects on hair shaft elongation were evaluated by quantitative (immuno)histomorphometry: HF cycling (anagen-catagen transition); hair matrix keratinocyte proliferation; expression of a key catagen inducer, transforming growth factor (TGF)-β2; and expression of the anagen-prolonging insulin-like growth factor (IGF)-1. Caffeine effects were further investigated in human outer root sheath keratinocytes (ORSKs).Results Caffeine enhanced hair shaft elongation, prolonged anagen duration and stimulated hair matrix keratinocyte proliferation. Female HFs showed higher sensitivity to caffeine than male HFs. Caffeine counteracted testosterone-enhanced TGF-β2 protein expression in male HFs. In female HFs, testosterone failed to induce TGF-β2 expression, while caffeine reduced it. In male and female HFs, caffeine enhanced IGF-1 protein expression. In ORSKs, caffeine stimulated cell proliferation, inhibited apoptosis/necrosis, and upregulated IGF-1 gene expression and protein secretion, while TGF-β2 protein secretion was downregulated.Conclusions This study reveals new growth-promoting effects of caffeine on human hair follicles in subjects of both sexes at different levels (molecular, cellular and organ). What's already known about this topic? Caffeine stimulates hair growth in androgen-sensitive testosterone-suppressed male human hair follicles (HFs) in vitro. What does this study add? The first evidence is presented for caffeine-stimulated growth of female human HFs, which are more caffeine sensitive than male HFs. Proliferation is increased by caffeine in human HF matrix keratinocytes in situ and in HF-derived outer root sheath keratinocytes (ORSKs). The catagen inducer transforming growth factor-β2 is downregulated, and the anagen-promoting factor insulin-like growth factor-1 is upregulated in human HFs in situ and in ORSKs. © 2014 British Association of Dermatologists.

Vidali S.,University of Lubeck | Knuever J.,University of Lubeck | Knuever J.,University of Cologne | Lerchner J.,TU Bergakademie Freiberg | And 8 more authors.
Journal of Investigative Dermatology | Year: 2014

Thyroid hormones regulate mitochondrial function. As other hypothalamic-pituitary-thyroid (HPT) axis hormones, i.e., thyrotropin-releasing hormone (TRH) and thyrotropin (TSH), are expressed in human hair follicles (HFs) and regulate mitochondrial function in human epidermis, we investigated in organ-cultured human scalp HFs whether TRH (30 nM), TSH (10 mU ml-1), thyroxine (T4) (100 nM), and triiodothyronine (T3) (100 pM) alter intrafollicular mitochondrial energy metabolism. All HPT-axis members increased gene and protein expression of mitochondrial-encoded subunit 1 of cytochrome c oxidase (MTCO1), a subunit of respiratory chain complex IV, mitochondrial transcription factor A (TFAM), and Porin. All hormones also stimulated intrafollicular complex I/IV activity and mitochondrial biogenesis. The TSH effects on MTCO1, TFAM, and porin could be abolished by K1-70, a TSH-receptor antagonist, suggesting a TSH receptor-mediated action. Notably, as measured by calorimetry, T3 and TSH increased follicular heat production, whereas T3 /T4 and TRH stimulated ATP production in cultured HF keratinocytes. HPT-axis hormones did not increase reactive oxygen species (ROS) production. Rather, T3 and T 4 reduced ROS formation, and all tested HPT-axis hormones increased the transcription of ROS scavengers (catalase, superoxide dismutase 2) in HF keratinocytes. Thus, mitochondrial biology, energy metabolism, and redox state of human HFs are subject to profound (neuro-)endocrine regulation by HPT-axis hormones. The neuroendocrine control of mitochondrial biology in a complex human mini-organ revealed here may be therapeutically exploitable. © 2014 The Society for Investigative Dermatology.

Discover hidden collaborations