Effects of Insulin and Insulin-Like Growth Factors on Cultured Human Hair Follicles: IGF-I at Physiologic Concentrations Is an Important Regulator of Hair Follicle Growth In Vitro

Philpott, Michael P.; Sanders, Deborah A.; Kealey, Terence

doi:10.1111/1523-1747.ep12382494

Cited by 269 publications

(199 citation statements)

References 21 publications

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“…One explanation for this association might be stimulating effect of insulin/insulin-like growth factor (IGF) system on hair follicle growth [24]. Phillot et al [25] also demonstrated that insulin/IGF system in vitro has a role on hair follicle growth. In tissues, IGF-1 is produced by mesenchymal type cells and acts in a paracrine and autocrine fashion by binding to the insulin-like growth factor 1 receptor (IGF-1R).…”

Section: Isi Homamentioning

confidence: 99%

Evaluation of various insulin sensitivity indices in lean idiopathic hirsutism patients

2012

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Hirsutism is characterized by excessive growth of terminal hair in a male pattern. Excessive hair growth in the absence of demonstrable androgen excess in ovulatory women is also referred to as idiopathic hirsutism (IH). IH is diagnosed in women who have hirsutism, normal ovulatory function and normal total or free testosterone levels. IH is a common cause of hirsutism. IH is not associated with any sign of virilization. Its cause is not understood completely. It has been proposed that women with IH have significantly increased cutaneous 5α-reductase activity. The presence or absence of such an association is not clear [1].Polycystic ovary syndrome (PCOS), another cause of hirsutism, is an insulin resistance related syndrome. Abstract. Hirsutism is characterized by excessive growth of terminal hair in a male pattern. Idiopathic hirsutism (IH) is a common cause of hirsutism. Since there are few data demonstrating IH is associated with insulin resistance, we tried to assess various insulin sensitivity indices in lean IH and compare with healthy subjects. A cross-sectional study was performed in 71 lean (BMI between 20-25 kg/m 2 ) women (17-39 years old), 31 with IH and 40 healthy individuals. Blood glucose, insulin, homeostasis model assessment of insulin resistance (HOMA-IR), hepatic insulin sensitivity (ISI HOMA ), Quicky index, reciprocal fasting insulin resistance index, fasting Belfiore index, and fasting glucose/insulin ratio (GIR) were estimated using a single fasting sample of glucose and insulin levels. Raynaud indices calculated using the mathematical estimation in a single fasting sample of insulin levels were determined and compared in two groups. Fasting insulin, Raynaud index, HOMA-IR and Fasting insulin resistance index (FIRI) results were higher in IH group than in controls (p<0.01, for all). Fasting Belfiore index, QUICKI index, ISI HOMA and FIRI -1 results were lower in IH group than in controls (p<0.01, for all). Our study showed that lean IH patients were more insulin resistant than healthy subjects. We propose that insulin sensitivity indices are useful methods for measuring insulin resistance in IH.Key words: Idiopathic hirsutism, Insulin resistance, Lean patients, Insulin sensitivity indices insulin resistance. There are few data demonstrating IH is associated with insulin resistance. Since the pathogenesis of IH is still unclear, we tried to assess various insulin sensitivity indices in lean IH and compare with healthy subjects. materials and methodsA cross-sectional study was performed in 71 lean (BMI between 20-25 kg/m 2 ) women (17-39 years old), 31 with IH and 40 healthy individuals. The protocol was approved by the hospital-based ethics committee. The protocol of the study was explained to all of the subjects. Informed consent was obtained before beginning the study.None of the control subjects had ovarian dysfunction, hirsutism, or hyperandrogenemia. The diagnosis of IH was based on the presence of hirsutism (modified Ferriman-Gallwey score, >8) [2], regular ovulatory menstrual cycles...

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Section: Isi Homamentioning

confidence: 99%

Evaluation of various insulin sensitivity indices in lean idiopathic hirsutism patients

2012

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“…In vitro, IGF-1 maintained hair follicles in a growth phase (anagen), and removal of IGF-1 led to a catagen-like regression. 24 Transgenic animals, in which an ultra-highsulfur keratin gene promoter was used to target IGF-1 to the wool follicles of the sheep or hair follicles of the mouse, showed increased fleece weight and vibrissae length, respectively. 25,26 Hair appeared earlier in transgenic mice overexpressing IGF-1 in the skin under control of the keratin 1 (K1) promoter.…”

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confidence: 99%

Overexpression of mIGF-1 in Keratinocytes Improves Wound Healing and Accelerates Hair Follicle Formation and Cycling in Mice

Semenova

Koegel

Hasse

et al. 2008

The American Journal of Pathology

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Insulin-like growth factor 1 (IGF-1) is an important regulator of growth, survival, and differentiation in many tissues. It is produced in several isoforms that differ in their N-terminal signal peptide and C-terminal extension peptide. The locally acting isoform of IGF-1 (mIGF-1) was previously shown to enhance the regeneration of both muscle and heart. In this study, we tested the therapeutic potential of mIGF-1 in the skin by generating a transgenic mouse model in which mIGF-1 expression is driven by the keratin 14 promoter. IGF-1 levels were unchanged in the sera of hemizygous K14/mIGF-1 transgenic animals whose growth was unaffected. A skin analysis of young animals revealed normal architecture and thickness as well as proper expression of differentiation and proliferation markers. No malignant tumors were formed. Normal homeostasis of the putative stem cell compartment was also maintained. Healing of full-thickness excisional wounds was accelerated because of increased proliferation and migration of keratinocytes, whereas inflammation, granulation tissue formation, and scarring were not obviously affected. In addition, mIGF-1 promoted late hair follicle morphogenesis and cycling. To our knowledge, this is the first work to characterize the simultaneous, stimulatory effect of IGF-1 delivery to keratinocytes on two types of regeneration processes within a single mouse model. Our analysis supports the use of mIGF-1 for skin and hair regeneration and describes a potential cell type-restricted action. (Am J

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“…For instance, manipulation of insulin-like growth factor (IGF) signalling in hair follicles by altering IGF-binding proteins or IGF-1 expression results in either abnormal curling of fibres or suppression of hair bending (Schlake, 2005). Given the known mitogenic effects of IGF-1 on the hair follicle (Philpott et al, 1994) and the agonistic or antagonistic effects of the insulin-like growth factor binding proteins (IGFBPs) on IGF-1 actions, it is tempting to speculate that the IGFs have differential effects on hair bending, depending on the relative effects of the growth factors on cell division and keratinisation rates.…”

Section: Discussionmentioning

confidence: 99%

Wool fibre crimp is determined by mitotic asymmetry and position of final keratinisation and not ortho- and para-cortical cell segmentation

Hynd

Edwards

Hebart

et al. 2009

Animal

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Crimp, a distinguishing feature of sheep fibres, significantly affects wool value, processing and final fabric attributes. Several explanations for fibre bending have been proposed. Most concentrate on relative differences in the physicochemical properties of the cortical cells, which comprise the bulk of the fibre. However, the associations between cortical properties and fibre crimp are not consistent and may not reflect the underlying causation of fibre curvature (FC). We have formulated a mechanistic model in which fibre shape is dictated primarily by the degree of asymmetry in cell supply from the follicle bulb, and the point at which keratinisation is completed within the follicle. If this hypothesis is correct, one would anticipate that most variations in fibre crimp would be accounted for by quantitative differences in both the degree of mitotic asymmetry in follicle bulbs and the distance from the bulb to the point at which keratinisation is completed. To test this hypothesis, we took skin biopsies from Merino sheep from sites producing wool differing widely in fibre crimp frequency and FC. Mitotic asymmetry in follicle bulbs was measured using a DNA-labelling technique and the site of final keratinisation was defined by picric acid staining of the fibre. The proportion of parato ortho-cortical cell area was determined in the cross-sections of fibres within biopsy samples. Mitotic asymmetry in the follicle bulb accounted for 0.64 ( P , 0.0001) of the total variance in objectively measured FC, while the point of final keratinisation of the fibre accounted for an additional 0.05 ( P , 0.05) of the variance. There was no association between ortho-to para-cortical cell ratio and FC. FC was positively associated with a subjective follicle curvature score ( P , 0.01). We conclude that fibre crimp is caused predominantly by asymmetric cell division in follicles that are highly curved. Differential pressures exerted by the subsequent asymmetric cell supply and cell hardening in the lower follicle cause fibre bending. The extent of bending is then modulated by the point at which keratinisation is completed; later hardening means the fibre remains pliable for longer, thereby reducing the pressure differential and reducing fibre bending. This means that even highly asymmetric follicles may produce a straight fibre if keratinisation is sufficiently delayed, as is the case in deficiencies of zinc and copper, or when keratinisation is perturbed by transgenesis. The model presented here can account for the many variations in fibre shape found in mammals.

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Effects of Insulin and Insulin-Like Growth Factors on Cultured Human Hair Follicles: IGF-I at Physiologic Concentrations Is an Important Regulator of Hair Follicle Growth In Vitro

Cited by 269 publications

References 21 publications

Evaluation of various insulin sensitivity indices in lean idiopathic hirsutism patients

Evaluation of various insulin sensitivity indices in lean idiopathic hirsutism patients

Overexpression of mIGF-1 in Keratinocytes Improves Wound Healing and Accelerates Hair Follicle Formation and Cycling in Mice

Wool fibre crimp is determined by mitotic asymmetry and position of final keratinisation and not ortho- and para-cortical cell segmentation

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