Portal de Periódicos da CAPES

Growth Hormone Operates as a Neuroendocrine Regulator of Human Hair Growth Ex Vivo

2019; Elsevier BV; Volume: 139; Issue: 7 Linguagem: Inglês

10.1016/j.jid.2018.12.022

1523-1747

Majid Alam, D. Below, Jérémy Chéret, Ewan A. Langan, Marta Bertolini, Francisco Jiménez, Ralf Paus,

Dermatology and Skin Diseases

The human hair follicle (HF) is a mini-organ that undergoes cyclical tissue remodeling, tightly coupled to profound hair cycle-dependent changes in follicular pigmentation (Oh et al., 2016Oh J.W. Kloepper J. Langan E.A. Kim Y. Yeo J. Kim M.J. et al.A guide to studying human hair follicle cycling in vivo.J Invest Dermatol. 2016; 136: 34-44Abstract Full Text Full Text PDF PubMed Scopus (163) Google Scholar, Paus and Cotsarelis, 1999Paus R. Cotsarelis G. The biology of hair follicles.N Engl J Med. 1999; 12: 491-497Google Scholar). To regulate these complex biological processes, among many other signals, the HF also recruits locally and/or systemically generated neurohormones and neuropeptides (Paus et al., 2014Paus R. Langan E.A. Vidali S. Ramot Y. Andersen B. Neuroendocrinology of the hair follicle: principles and clinical perspectives.Trends Mol Med. 2014; 20: 559-570Abstract Full Text Full Text PDF PubMed Scopus (86) Google Scholar). Indeed, a thorough characterization of the neuroendocrine regulation of human follicular biology, and its role in diseases affecting the HF, promises to help identify important novel neuroendocrine targets for therapeutic intervention. Although the role of prolactin in HF biology is increasingly appreciated (Foitzik et al., 2006Foitzik K. Krause K. Conrad F. Nakamura M. Funk W. Paus R. Human scalp hair follicles are both a target and a source of prolactin, which serves as an autocrine and/or paracrine promoter of apoptosis-driven hair follicle regression.Am J Pathol. 2006; 168: 748-756Abstract Full Text Full Text PDF PubMed Scopus (118) Google Scholar, Langan, 2018Langan E.A. Prolactin and human skin—the effects of sex and site on expression and function.Endocrine. 2018; 59: 700-701Google Scholar, Ramot et al., 2010Ramot Y. Bíró T. Tiede S. Tóth B.I. Langan E.A. Sugawara K. et al.Prolactin—a novel neuroendocrine regulator of human keratin expression in situ.Soc Exp Biol. 2010; 24 (FASEB J Off Publ Fed Am Soc, 2010): 1768-1779Google Scholar.), the role of several other pituitary-derived hormones in human HF biology, notably that of growth hormone (GH), remains to be fully characterized and explored. Human GH (also called somatotropin) is a 191-amino acid polypeptide secreted by the somatotrophs of the anterior pituitary gland (Bartke and Darcy, 2017Bartke A. Darcy J. GH and ageing: pitfalls and new insights.Best Pract Res Clin Endocrinol Metab. 2017; 31: 113-125Crossref PubMed Scopus (48) Google Scholar). Human skin is an important target for GH, with both GH excess and deficiency being associated with phenotypic changes, namely, hypertrichosis/hirsutism and thin, brittle hair, respectively (Kanaka-Gantenbein et al., 2016Kanaka-Gantenbein C. Kogia C. Abdel-Naser M.B. Chrousos G.P. Skin manifestations of growth hormone-induced diseases.Rev Endocr Metab Disord. 2016; 17: 259-267Crossref PubMed Scopus (20) Google Scholar). GH receptor (GHR) expression has been reported in dermal fibroblasts, epidermal keratinocytes, sebocytes, melanocytes, outer root sheath (ORS), and matrix keratinocytes of human HFs (Póvoa and Diniz, 2011Póvoa G. Diniz L.M. Growth hormone system: skin interactions.An Bras Dermatol. 2011; 86: 1159-1165Google Scholar). Despite these well-known clinical associations and the recognized intrafollicular GHR expression, the function of GH in human HFs remains to be systematically investigated. Therefore, after having confirmed and further characterized GHR expression in female human HFs (see below), we hypothesized in this pilot study that pituitary GH may be an undiscovered hair growth regulator in human scalp skin via GHR-mediated signaling. To probe this hypothesis, we asked whether microdissected, organ-cultured human scalp HFs (Langan et al., 2015Langan E.A. Philpott M.P. Kloepper J.E. Paus R. Human hair follicle organ culture: theory, application and perspectives.Exp Dermatol. 2015; 24: 903-911Crossref PubMed Scopus (106) Google Scholar) directly respond to GH stimulation in the absence of systemic endocrine stimuli by assessing changes in human HF cycling, growth, and pigmentation and the expression of the key hair growth regulators IGF-1 and transforming growth factor-β2 (Chéret et al., 2018Chéret J. Bertolini M. Ponce L. Lehmann J. Tsai T. Alam M. et al.Olfactory receptor OR2AT4 regulates human hair growth.Nat Commun. 2018; 9: 3624Google Scholar, Kloepper et al., 2010Kloepper J.E. Sugawara K. Al-Nuaimi Y. Gáspár E. van Beek N. Paus R. Methods in hair research: how to objectively distinguish between anagen and catagen in human hair follicle organ culture.Exp Dermatol. 2010; 19: 305-312Crossref PubMed Scopus (100) Google Scholar). To exclude potential sex- or location-dependent GH effects, only occipital HFs from female patients undergoing routine facelift surgery were used (see Supplementary TableS1 online). Written informed patient consent and an institutional ethics license (University of Münster 2014-041-b-N and 2015-602-f-S) were obtained. Immunohistochemistry confirmed GHR protein expression in healthy female human scalp skin, which was particularly prominent in the HF epithelium, in line with previous studies (Ginarte et al., 2000Ginarte M. García-Caballero T. Fernández-Redondo V. Beiras A. Toribio J. Expression of growth hormone receptor in benign and malignant cutaneous proliferative entities.J Cutan Pathol. 2000; 27: 276-282Crossref PubMed Scopus (33) Google Scholar, Lobie et al., 1990Lobie P.E. Breipohl W. Lincoln D.T. García Aragón J. Waters M.J. Localization of the growth hormone receptor/binding protein in skin.J Endocrinol. 1990; 126: 467-471Crossref PubMed Scopus (99) Google Scholar), with both cytoplasmic and nuclear GHR protein expression seen in ORS keratinocytes (Figure 1a ). Quantitative reverse transcriptase–PCR of mRNA extracts from HFs not only confirmed substantial intrafollicular GHR transcription in human anagen HFs but also showed a decline in GHR mRNA expression in female catagen versus anagen VI HFs (Figure 1b, and see Supplementary Figure S1 online), suggesting that human anagen VI HFs are more receptive to GH stimulation than regressing catagen HFs. Next, we explored whether these intrafollicular GHRs are functional and whether their stimulation by exogenous GH alters human hair growth and/or pigmentation ex vivo. Female occipital scalp HFs were stimulated over 6 days with recombinant human GH (Sigma-Aldrich, St. Louis, MO) at a concentration of 100 ng/ml (the level seen in patients suffering from acromegaly) (Espinosa de los Monteros et al., 2018Espinosa de los Monteros A.L. Sosa-Eroza E. Gonzalez B. Mendoza V. Mercado M. Prevalence, clinical and biochemical spectrum and treatment outcome of acromegaly with normal basal GH at diagnosis.J Clin Endocrinol Metab. 2018; 103: 3919-3924Google Scholar), and quantitative hair cycle histomorphometry was performed as described previously (Hawkshaw et al., 2018Hawkshaw N.J. Hardman J.A. Haslam I.S. Shahmalak A. Gilhar A. Lim X. et al.Identifying novel strategies for treating human hair loss disorders: cyclosporine A suppresses the Wnt inhibitor, SFRP1, in the dermal papilla of human scalp hair follicles.PLoS Biol. 2018; 16: e2003705Crossref PubMed Scopus (48) Google Scholar, Kloepper et al., 2010Kloepper J.E. Sugawara K. Al-Nuaimi Y. Gáspár E. van Beek N. Paus R. Methods in hair research: how to objectively distinguish between anagen and catagen in human hair follicle organ culture.Exp Dermatol. 2010; 19: 305-312Crossref PubMed Scopus (100) Google Scholar). As shown in Figure 2a, b, and h, 100 ng/ml recombinant growth hormone induced premature catagen development. A significant acceleration of catagen development in recombinant growth hormone–treated HFs ex vivo was independently confirmed by calculating the hair cycle score (P < 0.01) (Samuelov et al., 2012Samuelov L. Kinori M. Bertolini M. Paus R. Neural controls of human hair growth: calcitonin gene-related peptide (CGRP) induces catagen.J Dermatol Sci. 2012; 67: 153-155Abstract Full Text Full Text PDF PubMed Scopus (20) Google Scholar) (Figure 2b ), and a reduced percentage of proliferating hair matrix keratinocytes below Auber's line was determined (P < 0.0538) (Figure 2c) by quantitative Ki-67 immunohistomorphometry in GH-stimulated HFs when all HFs (i.e., anagen and catagen) were assessed, as well as when only anagen VI HFs were assessed (see Supplementary Figure S2 online). No significant difference was found in the histomorphometrically quantified melanin content of test and control HFs when only anagen VI HFs were compared with each other (Figure 2d), suggesting that GH does not inhibit follicular melanogenesis in a hair cycle-dependent manner. Thus, GH induces complex HF regression changes that promote the catagen transformation of this mini-organ, at least ex vivo, but does not appear to exert hair cycle-independent effects on human HF melanocytes in situ, in striking contrast to thyrotropin-releasing hormone (Gáspár et al., 2011Gáspár E. Nguyen-Thi K.T. Hardenbicker C. Tiede S. Plate C. Bodó E. et al.Thyrotropin-releasing hormone selectively stimulates human hair follicle pigmentation.J Invest Dermatol. 2011; 131: 2368-2377Abstract Full Text Full Text PDF PubMed Scopus (39) Google Scholar), another recognized key neuroendocrine regulator of human hair biology (Gáspár et al., 2010Gáspár E. Hardenbicker C. Bodó E. Wenzel B. Ramot Y. Funk W. et al.Thyrotropin releasing hormone (TRH): a new player in human hair-growth control.FASEB J Off Publ Fed Am Soc Exp Biol. 2010; 24: 393-403Crossref PubMed Scopus (61) Google Scholar, Paus et al., 2014Paus R. Langan E.A. Vidali S. Ramot Y. Andersen B. Neuroendocrinology of the hair follicle: principles and clinical perspectives.Trends Mol Med. 2014; 20: 559-570Abstract Full Text Full Text PDF PubMed Scopus (86) Google Scholar, Ramot et al., 2013Ramot Y. Zhang G. Bíró T. Langbein L. Paus R. Is thyrotropin-releasing hormone a novel neuroendocrine modulator of keratin expression in human skin?.Br J Dermatol. 2013; 169: 146-151Crossref PubMed Scopus (8) Google Scholar, Vidali et al., 2014Vidali S. Knuever J. Lerchner J. Giesen M. Bíró T. Klinger M. et al.Hypothalamic-pituitary-thyroid axis hormones stimulate mitochondrial function and biogenesis in human hair follicles.J Invest Dermatol. 2014; 134: 33-42Abstract Full Text Full Text PDF PubMed Scopus (56) Google Scholar). Finally, we showed that HF stimulation with GH ex vivo significantly up-regulated the intrafollicular protein expression of IGF-1 in the ORS (Figure 2e and i), that is, the key peripheral tissue mediator of GH bioactivity (Cooke et al., 2016Cooke D.W. Divall S.A. Radovick S. Normal and aberrant growth in children.in: Melmed S. Polonsky K.S. Larsen P.R. Lronenberg H.M. Williams Textbook of Endocrinology. 13th ed. Elsevier Saunders, Philadelphia, PA2016: 964-999Google Scholar) and a known key growth factor that promotes anagen maintenance (Chéret et al., 2018Chéret J. Bertolini M. Ponce L. Lehmann J. Tsai T. Alam M. et al.Olfactory receptor OR2AT4 regulates human hair growth.Nat Commun. 2018; 9: 3624Google Scholar, Schneider et al., 2009Schneider M.R. Schmidt-Ullrich R. Paus R. The hair follicle as a dynamic miniorgan.Curr Biol. 2009; 19: R132-R142Abstract Full Text Full Text PDF PubMed Scopus (622) Google Scholar). However, this was coupled with a significant increase in protein expression of the key catagen-promoting growth factor, TGF-β2 (Ramot et al., 2013Ramot Y. Zhang G. Bíró T. Langbein L. Paus R. Is thyrotropin-releasing hormone a novel neuroendocrine modulator of keratin expression in human skin?.Br J Dermatol. 2013; 169: 146-151Crossref PubMed Scopus (8) Google Scholar, Vidali et al., 2014Vidali S. Knuever J. Lerchner J. Giesen M. Bíró T. Klinger M. et al.Hypothalamic-pituitary-thyroid axis hormones stimulate mitochondrial function and biogenesis in human hair follicles.J Invest Dermatol. 2014; 134: 33-42Abstract Full Text Full Text PDF PubMed Scopus (56) Google Scholar), not only in the HF epithelium but, most prominently, also in the dermal papilla (Figure 2g and i), where TGF-β2 protein is notably expressed during catagen induction (Fischer et al., 2014Fischer T.W. Herczeg-Lisztes E. Funk W. Zillikens D. Bíró T. Paus R. Differential effects of caffeine on hair shaft elongation, matrix and outer root sheath keratinocyte proliferation, and transforming growth factor-β2/insulin-like growth factor-1-mediated regulation of the hair cycle in male and female human hair follicles in vitro.Br J Dermatol. 2014; 171: 1031-1043Crossref Scopus (41) Google Scholar, Hibino and Nishiyama, 2004Hibino T. Nishiyama T. Role of TGF-beta2 in the human hair cycle.J Dermatol Sci. 2004; 35: 9-18Abstract Full Text Full Text PDF PubMed Scopus (163) Google Scholar). This suggests that GH-induced premature catagen development in female human HFs likely results from a functionally dominant increase in TGF-β2 expression, namely, in the "mesenchymal command center" of the HF (i.e., the follicular dermal papilla), which cannot be overridden by the up-regulation of IGF-1 upon GH stimulation. In summary, our pilot study shows not only that GHR-expressing human scalp HFs in anagen VI are highly receptive to GH stimulation but also that GH operates as a neuroendocrine inhibitor of female human HFs ex vivo, despite the well-documented overall growth-promoting properties of GH in many other tissues (Kaiser et al., 2016Kaiser U. Ho K.K.Y. Pituitary physiology and diagnostic evaluation.in: Melmed S. Polonsky K.S. Larsen P.R. Kronenberg H.M. Williams textbook of endocrinology. 13th ed. Elsevier, Philadelphia2016: 176-231Google Scholar), possibly via up-regulating intrafollicular TGF-β2 production. We also show that human HF organ culture provides an excellent research tool for interrogating the as yet insufficiently explored peripheral effects of GH/GHR-dependent signaling in adult human tissues (Ocaranza et al., 2016Ocaranza P. Morales F. Matamala Á. Gaete X. Román R. Lammoglia J.J. et al.Growth hormone signaling in fibroblasts from newborn boys and prepubertal boys.Growth Horm IGF Res. 2016; 27: 18-27Crossref PubMed Scopus (5) Google Scholar, Wang et al., 2017Wang J.-J. Chong Q.-Y. Sun X.-B. You M.-L. Pandey V. Chen Y.-J. et al.Autocrine hGH stimulates oncogenicity, epithelial-mesenchymal transition and cancer stem cell-like behavior in human colorectal carcinoma.Oncotarget. 2017; 8: 103900-103918Google Scholar). Future studies now will have to clarify whether human HFs also express GH itself, just as they express prolactin, thyrotropin-releasing hormone, corticotropin-releasing hormone, proopiomelanocortin-derived hormones (Paus et al., 2014Paus R. Langan E.A. Vidali S. Ramot Y. Andersen B. Neuroendocrinology of the hair follicle: principles and clinical perspectives.Trends Mol Med. 2014; 20: 559-570Abstract Full Text Full Text PDF PubMed Scopus (86) Google Scholar), and/or additional players of the GH signaling axis, namely GH-releasing hormone. Moreover, future studies should clarify whether there are sex- and/or location-dependent differences in the response of human HFs to GH stimulation. Given the clinical skin manifestations associated with abnormalities in GH serum levels and the currently available treatments (see Supplementary Materials), further elucidating the role of GH/GHR-dependent signaling could pave the way for the development of future therapeutics. Majid Alam: http://orcid.org/0000-0002-5783-6605 The authors state no conflict of interest. This study was supported in part by a basic research grant from Monasterium Laboratory, Skin & Hair Research Solutions GmbH, Münster, Germany to MA, DAB, JC, MB, and RP when the authors were jointly working at the Department of Dermatology, University of Münster. MA performed the experiments and analyzed data with substantial help from DAB. MA, EAL, and RP wrote the manuscript. MA and RP conceived, designed, supervised the study, and interpreted the data. All authors contributed to data analysis and writing of the manuscript. Download .pdf (.13 MB) Help with pdf files Supplementary Data