Cytokine gene expression in intact anagen rat hair follicles

Hair follicle development and related gene and protein expression of skins in Rex rabbits during the first 8 weeks of life

Objective

We aimed to observe hair follicle (HF) development in the dorsal skin and elucidate the expression patterns of genes and proteins related to skin and HF development in Rex rabbits from birth to 8 weeks of age.

Methods

Whole-skin samples were obtained from the backs of Rex rabbits at 0, 2, 4, 6, and 8 weeks of age, the morphological development of primary and secondary HFs was observed, and the gene transcript levels of insulin-like growth factor-I (IGF-I), epidermal growth factor (EGF), bone morphogenetic protein 2 (BMP2), transforming growth factor β-1, 2, and 3 (TGFβ-1, TGFβ-2, and TGFβ-3) were examined using quantitative real-time polymerase chain reaction (PCR). Additionally, Wnt family member 10b (Wnt10b) and β-Catenin gene and protein expression were examined by quantitative real-time PCR and western blot, respectively.

Results

The results showed significant changes in the differentiation of primary and secondary HFs in Rex rabbits during their first 8 weeks of life. The IGF-I, EGF, TGFβ-2, and TGFβ-3 transcript levels in the rabbits were significantly lower at 2 weeks of age than at birth and gradually increased thereafter, while the BMP2 and TGFβ-1 transcript levels at 2 weeks of age were significantly higher than those at birth and gradually decreased thereafter. β-Catenin gene expression was also significantly affected by age, while the Wnt10b transcript level was not. However, the Wnt10b and β-catenin protein expression levels were the lowest at 2 and 4 weeks of age.

Conclusion

Our data showed that a series of changes in HFs in dorsal skin occurred during the first 8 weeks. Many genes, such as IGF-I, EGF, BMP2, TGFβ-1, TGFβ-2, TGFβ-3, and β-Catenin, participated in this process, and the related proteins Wnt10b and β-Catenin in skin were also affected by age.

Igf1r signalling acts on the anagen-to-catagen transition in the hair cycle

Insulin-like growth factor 1 (Igf1) is important for skin development and homoeostasis. However, overexpression and inactivation studies have produced variable findings regarding its role in hair follicle (HF) biology. Here, we studied a conditional and inducible knockout of the Igf1 receptor (Igf1r) in keratin 15-expressing bulge cells. Deletion of Igf1r after the development of the skin appendages in K15-Igf1r^KO mice showed no abnormalities in epidermal homoeostasis. Numbers of bulge cells were lower in K15-Igf1r^KO mice than in controls, without consequences on wound healing, at least in young mice. K15-Igf1r^KO HFs entered anagen phase earlier than controls and showed a delay in the anagen/catagen switch. The expression of Bmp-4 mRNA was inhibited in HFs from K15-Igf1r^KO . MED1 transcription was impaired in the epidermis of K15-Igf1r^KO mice. These findings suggest that Igf1r controls the hair cycle, partly through Bmp-4 activation.

Exploring differentially expressed genes by RNA-Seq in cashmere goat (Capra hircus) skin during hair follicle development and cycling

Cashmere goat (Capra hircus) hair follicle development and cycling can be divided into three stages: anagen, catagen and telogen. To elucidate the genes involved in hair follicle development and cycling in cashmere goats, transcriptome profiling of skin was carried out by analysing samples from three hair follicle developmental stages using RNA-Seq. The RNA-Seq analysis generated 8487344, 8142514 and 7345335 clean reads in anagen, catagen and telogen stages, respectively, which provided abundant data for further analysis. A total of 1332 differentially expressed genes (DEGs) were identified, providing evidence that the development of hair follicles among the three distinct stages changed considerably. A total of 683 genes with significant differential expression were detected between anagen and catagen, 530 DEGs were identified between anagen and telogen, and 119 DEGs were identified between catagen and telogen. A large number of DEGs were predominantly related to cellular process, cell & cell part, binding, biological regulation and metabolic process among the different stages of hair follicle development. In addition, the Wnt, Shh, TGF-β and Notch signaling pathways may be involved in hair follicle development and the identified DEGs may play important roles in these signaling pathways. These results will expand our understanding of the complex molecular mechanisms of hair follicle development and cycling in cashmere goats and provide a foundation for future studies.

Uncommonly reported side effects of hair removal by long pulsed-alexandrite laser

OBJECTIVE

To provide retrospective clinical review of some uncommonly reported side effects of long-pulsed alexandrite laser treatment for hair removal.

MATERIAL AND METHODS

Two hundred and fifty female patients suffering from hirsutism of the face were subjected to treatment by long pulse alexandrite laser for a maximum of 15 sessions per patient at 5- to 7-week intervals.

RESULTS

Apart from the commonly reported side effects of pigmentary changes, occasional blistering and rare scarring, other untoward effects have been observed. These include - among others - de-novo growth of hair outside the area treated by laser, potentiation of co-existing vellus hair in the treatment area, induction or aggravation of acne, rosacea-like rash, premature grayness of hair, tunneling of hair under the skin, prolonged diffuse redness and edema of the face, focal hypopigmentation of the lip, angular cheilitis, allergic reaction to the cooling gas, and inflammatory and pigmentary changes of pre-existing nevi.

CONCLUSION

Although the efficacy of long-pulsed alexandrite laser seems unmistakable, the short- and long-term untoward effects of such treatment have yet to be carefully delineated and the underlying mechanisms are yet to be adequately clarified.

Estrogens and the hair follicle. Ostrogene und der Haarfollikel

While it is undisputed that estrogens (1 beta-estradiol, E2) are mainly involved in skin physiology and operate as potent hair growth modulators, our knowledge about the estrogen target cells in skin and exact signaling pathways is still very limited. The current review provides an overview of estrogen effects on hair follicle cycling, cutaneous expression of estrogen receptors, and potential functions of estrogens in hair biology. We discuss potential target genes of estrogen receptor-mediated signaling in the skin, explore the interplay of estrogens with other hormones, growth factors and enzymes, and define major open questions in this intriguing and far too long neglected area of hair research.

Production of a monoclonal antibody, DF-5, that identifies cells at the epithelial-mesenchymal interface in normal human skin. APN/CD13 is an epithelial-mesenchymal marker in skin

Epithelial-mesenchymal interactions play a critical role in skin development and differentiation, and similar interactions may also regulate the day-to-day proliferation and differentiation events of the epidermis that occur in normal adult skin. This study was directed at identifying molecules that are selectively located at the dermal-epidermal junction in normal adult skin as they may be involved in regulating these homeostatic events. To this end, monoclonal antibodies were raised against the crude cell membrane fraction of cultured human dermal fibroblasts. Screening of antibodies that recognized cell surface antigen on cultured human dermal fibroblasts was followed by determining which of these antibodies selectively localized cells at sites of epithelial-mesenchymal interactions. Antibody DF-5 fit these criteria and was further characterized. This antibody was found to recognize the cell surface ectopeptidase aminopeptidase N (APN), a molecule homologous to the cluster differentiation antigen CD13. Antibody DF-5 and anti-CD13 antibodies both identified cells at sites of epithelial-mesenchymal interactions in fetal, neonatal, and adult human skin, and the APN/CD13 enzyme activity was also identified at these sites. A second ectopeptidase, dipeptidyl peptidase IV (DPPIV) or CD26, presented a significantly different immunohistochemical and histochemical pattern in skin samples, confirming the specificity of the APN/CD13 studies. The function of APN/CD13 in skin has yet to be determined. Its invariant localization at sites of epithelial-mesenchymal interactions argues for a role particular to this region. It may play a role in regulating the activity of neuropeptides or other signaling peptides that are released in this region of skin or it may have an as yet undefined role in mediating communication between dermal and epidermal cells.

Antinerve growth factor treatment prevents intestinal dysmotility in Trichinella spiralis-infected rats

Nerve growth factor (NGF) could be involved in the development of hyperalgesia as well as in nervous remodeling consequence of inflammation. Both dysmotility and increase of visceral sensitivity have been described in functional gastrointestinal disorders such as irritable bowel syndrome. Trichinella spiralis-infected rats show an exacerbated spontaneous motility and a significant increase of the excitatory response to cholecystokinin (CCK), both associated with a reversible inflammatory process and the hypertrophy of the muscle layers. In this study we determined the intestinal expression of NGF mRNA by polymerase chain reaction and NGF by enzyme-linked immunosorbent assay. We implanted serosal strain gauge transducers on duodenum, jejunum, and ileum of anesthetized Sprague-Dawley rats to record circular muscle contractions. The experimental protocol included the evaluation of intestinal spontaneous motor activity (SMA), the response to CCK-8, and the ascending contraction induced by electrical mucosal stimulation. This protocol was performed in healthy and infected nontreated rats, in healthy rats with an NGF antibody treatment (1.6 mg/rat i.p.), and in infected rats with the same treatment applied at 0 or 3 days postinfection. NGF and NGF mRNA levels in the bowel were increased during inflammation. Although anti-NGF treatments did not prevent or reverse inflammatory response, the treatment was effective in preventing the motor alterations induced by the T. spiralis infection, i.e., inhibited increased SMA, reversed altered response to CCK, and reversed in part exacerbated response to electrical stimulation.

Human follicular papilla cells carry out nonadipose tissue production of leptin

Leptin, a satiety-regulating cytokine, is predominantly expressed by adipocytes, although recently the nonadipose tissue production of leptin has been reported. To investigate the possibility of leptin production by human scalp hair follicles, we examined leptin production and its mRNA expression by cultured human follicular papilla cells. We isolated 12 human follicular papilla cell lines from different individuals. They were identified by their morphology, their high alpha-smooth-muscle actin expression, their inability to differentiate into adipocytes, and by the lack of mRNA for adipose-specific fatty acid binding protein. All the human follicular papilla cell lines, but not neonatal human dermal fibroblasts, produced significant amounts of leptin demonstrable by enzyme-linked immunosorbent assay. We demonstrated leptin mRNA expression by human follicular papilla cell lines, but not by neonatal human dermal fibroblasts, by reverse transcription polymerase chain reaction. By immunohistochemistry and in situ hybridization, we detected both leptin protein and mRNA at the lower portion of the hair follicle, i.e., hair matrix, inner root sheath of the hair bulb, and human follicular papilla cells. In contrast, the leptin receptor with intracytoplasmic signal sequence was detected in the follicular papilla cells immunohistochemically, and the long isoform of the leptin receptor mRNA was demonstrated in the human follicular papilla cell lines by reverse transcription polymerase chain reaction. Finally, by using these human follicular papilla cell lines, we showed that cytokines such as interleukin-1 beta, tumor necrosis factor alpha, interferon-gamma, and interleukin-4, and growth factors such as epidermal growth factor, basic fibroblast growth factor, and transforming growth factor beta1, but not vascular endothelial growth factor, hepatocyte growth factor, keratinocyte growth factor, and insulin-like growth factor 1, significantly downregulated the production of leptin. These data demonstrated that human follicular papilla cells produce leptin and express the functional leptin receptor in vivo and in vitro, suggesting its autocrine function. Moreover, the regulation pattern of its production by various factors suggests a pivotal role of leptin in hair biology.

Histologic study of the regeneration process of human hair follicles grafted onto SCID mice after bulb amputation

This study examines histologically the degeneration and subsequent regeneration processes of human hair follicles whose bulb is severely damaged. Human scalp hair follicles were isolated and grafted onto immunodeficient mice after their bulb was amputated. On day 14, thickening and corrugation of the vitreous membrane, apoptosis of follicular keratinocytes, and regression of the lower portion of the follicles were observed. By day 20, mesenchymal cells had accumulated around the lower end of the follicles. From day 14 through 50, the follicular regression and apoptosis continued, and between days 30 and 40 the follicles became maximally shortened, and the vitreous membrane disappeared. By day 50 the lower end of the follicles had become cup-shaped, and the cup surrounded an aggregate of mesenchymal cells that corresponded to the dermal papilla. By day 60, all the grafted follicles had developed into anagen VI follicles, and the apoptosis had ceased. These results indicate that human scalp hair follicles whose bulb is completely destroyed enter into dystrophic telogen after restoration of the dermal papilla, then into anagen, and that the duration of the dystrophic telogen is shorter than that of the normal hair cycle.

Controls of hair follicle cycling

Nearly 50 years ago, Chase published a review of hair cycling in which he detailed hair growth in the mouse and integrated hair biology with the biology of his day. In this review we have used Chase as our model and tried to put the adult hair follicle growth cycle in perspective. We have tried to sketch the adult hair follicle cycle, as we know it today and what needs to be known. Above all, we hope that this work will serve as an introduction to basic biologists who are looking for a defined biological system that illustrates many of the challenges of modern biology: cell differentiation, epithelial-mesenchymal interactions, stem cell biology, pattern formation, apoptosis, cell and organ growth cycles, and pigmentation. The most important theme in studying the cycling hair follicle is that the follicle is a regenerating system. By traversing the phases of the cycle (growth, regression, resting, shedding, then growth again), the follicle demonstrates the unusual ability to completely regenerate itself. The basis for this regeneration rests in the unique follicular epithelial and mesenchymal components and their interactions. Recently, some of the molecular signals making up these interactions have been defined. They involve gene families also found in other regenerating systems such as fibroblast growth factor, transforming growth factor-beta, Wnt pathway, Sonic hedgehog, neurotrophins, and homeobox. For the immediate future, our challenge is to define the molecular basis for hair follicle growth control, to regenerate a mature hair follicle in vitro from defined populations, and to offer real solutions to our patients' problems.

Increased vibrissa growth in transgenic mice expressing insulin-like growth factor 1

Insulin-like growth factor 1 (IGF-1) mediates many of the actions of growth hormone. Overexpression of IGF-1 has been reported to have endocrine and paracrine/autocrine effects on somatic growth in transgenic mice. To study the paracrine/autocrine effects of IGF-1 in hair follicles, transgenic mice were produced by pronuclear microinjection of a construct containing a mouse ultra-high sulfur keratin (UHS-KER) promoter linked to an ovine IGF-1 cDNA. This UHS-KER promoter has previously been shown to direct expression of a reporter gene to the hair follicles of transgenic mice. Four transgenic mouse lines were established as a result of microinjection of 435 embryos. Transgene expression was found in skin at day 8 and day 15 of age in three of the lines. Progeny tests were carried out by mating two of the transgenic expressing males to nontransgenic females. Mice from one line were all nonexpressors while four of the 12 mice from the other showed integration of the transgene and three expressed transgene IGF-1 mRNA in the skin. Vibrissa growth at 11-21 d of age was significantly greater in transgenic expressors than in their nontransgenic littermates. Specifically, the increase in vibrissa length for transgenics at days 11-16 (20.5%) is approximately 2-fold compared with days 16-21 (11.9%). These results demonstrate that local overexpression of IGF-1 in transgenic mice is capable of stimulating vibrissa growth during the first neonatal hair cycle.

Analysis of apoptotic cell death in human hair follicles in vivo and in vitro

We analyzed changes of growth and apoptotic cell death in human hair follicles. In anagen hair follicles, terminal deoxynucleotidyltransferase-mediated deoxyuridine triphosphate-biotin nick labeling-positive cells were observed in the keratogenous zone of the upper bulb matrix, the inner root sheath, and the companion layer of the outer root sheath. DNA ladder formation was also detected in anagen hair follicles. In catagen hair follicles, the lower bulb matrix cells around the dermal papilla and the outer layer cells of the outer root sheath became strongly positive, showing that apoptosis in catagen hair is distinct from that in anagen hair. We also confirmed the mRNA expression of four caspases (caspase-1, caspase-3, caspase-4, and caspase-7) in anagen hair follicles by reverse transcriptase-polymerase chain reaction and in situ hybridization. When human anagen hair follicles were cultured in the presence of transforming growth factor-beta or tumor necrosis factor-alpha in the serum-free medium, transforming growth factor-beta but not tumor necrosis factor-alpha induced catagen-like morphologic changes, which were indistinguishable from normal catagen hair follicles. Tumor necrosis factor-alpha, however, strongly inhibited the elongation of the hair shaft in a dose-dependent manner, accompanied by abnormal morphology and increased cell death in the bulb matrix cells. Our results suggest that apoptosis in hair follicles involves two different types. One is related to the terminal differentiation of follicular epithelial cells in anagen hair. The other occurs as a major driving force to eliminate the distinct portion of epithelial components in catagen hair. Furthermore, this study strongly indicates that the transforming growth factor-beta pathway is involved in the induction of catagen phase in human hair cycle.

The role of IGF-I in human skin and its appendages: morphogen as well as mitogen?

Previous studies have investigated the expression of insulin-like growth factor-I (IGF-I) and its receptor in cultured skin cells or in whole skin. In order to fully understand the role of IGF-I in the skin and its appendages, however, a comprehensive study that details the expression of IGF-I and the IGF-I receptor in sections of human skin is needed. Therefore, we now report an immunocytochemical and in situ hybridization localization study of the cell types expressing IGF-I and its receptor in human adult skin and its appendages. We have observed that (i) dermal fibroblasts produce IGF-I, (ii) the epidermal basal keratinocytes are IGF-I negative but IGF-I receptor positive, and (iii) the keratinocytes of the stratum granulosum produce IGF-I. These observations indicate either that the mitogenesis of the basal keratinocytes is regulated by IGF-I expressed both in the dermis and in the stratum granulosum, or that dermal fibroblasts are responsible for sequestering IGF-I to the basal keratinocytes and that the stratum granulosum-derived IGF-I may be an autocrine regulator of epidermal differentiation. The distribution of IGF-I and its receptor in the hair follicle indicates that IGF-I may be a morphogen, not a mitogen, at those sites, because their proliferating cells, but not their differentiating cells, are IGF-I receptor negative. Further, IGF-I receptor expression by the dermal papilla appears to be switched off during the transition from anagen to catagen, which implies a regulatory role for IGF-I during the hair growth cycle.

Localisation of insulin-like growth factor receptors in skin follicles of sheep (Ovis aries) and changes during an induced growth cycle

Pelage growth cycles are regulated by circulating prolactin in many mammals, but the intercellular mediators of this signaling are unknown. Binding sites for insulin-like growth factors (IGFs) were examined in sheep skin to show changes in distribution and abundance of IGF receptors associated with a prolactin stimulus and the subsequent hair follicle growth cycle. Follicle cycles were induced in New Zealand Wiltshire ewes by a surge in plasma prolactin following a 4-month period of prolactin suppression with bromocriptine. Eight treated and three control sheep were slaughtered at intervals over 43 days during the follicle growth cycle. At 12-20 days after the elevation of prolactin, wool follicles passed through brief catagen and telogen phases, followed by a return to anagen. IGF binding sites were localized in skin sections by incubation with 125I-IGF-I or 125I-IGF-II. Displacement with competitive binding inhibitors (unlabeled IGF-I, IGF-II, des(1-3)IGF-I, des(1-6)IGF-II, or insulin) and affinity cross-linking showed that these binding sites were predominantly IGF type 1 and type 2 (mannose-6-phosphate) receptors. The radioligands bound especially to follicle germinal cells and prekeratinocytes. Increases in specific binding of both radioligands were observed after the rise in prolactin, but prior to anatomical changes in follicles associated with cessation of growth. For IGF-I, highest binding density was observed during catagen in the germinal matrix and dermal papilla cells. For IGF-II, peak density occurred during late anagen/early catagen in the germinal matrix and during telogen in the dermal papilla. These cycle associated changes in receptor availability suggest that IGF receptors are involved in control of the wool growth.

Hair follicle growth controls

Research in hair biology has embarked in the pursuit for molecules that control hair growth. Many molecules already have been associated with the controls of hair patterning, hair maturation, and hair cycling and differentiation. Knowing how these molecules work gives us the tools for understanding and treating patients with hair disorders.

Growth factors in hair organ development and the hair growth cycle

Growth factors are polypeptides that regulate growth and differentiation of many cell types. Different growth factor families including the epidermal growth factor (EGF)-related ligands, fibroblast growth factors (FGF), transforming growth factor-beta (TGF-beta), insulin-like growth factor (IGF), hepatocyte growth factor/scatter factor (HGF/SF), and platelet-derived growth factor (PDGF) have been shown to be crucial for the regulation of the hair cycle and hair growth. Growth factors and their receptors have been localized to the skin and hair follicles. Their biological activities on cells comprising the hair follicle have been tested in vitro and increasingly in transgenic mice. Herein we review selected important aspects of growth factors with regard to the hair organ, its development, and the hair growth cycle.

Long-term expression of transforming growth factor TGF beta 1 in mouse skin after localized beta-irradiation

The long-term expression of TGF beta 1 in mouse skin after localized irradiation with a beta-emitting source is reported. The skin of CBA/ca mice was exposed to 50 Gy superficial beta radiation from an 11 mm strontium-90 source. Such a dose produced an acute moist desquamation reaction in 100% of the animals, which was macroscopically resolved within 30 days. The acute response was followed by progressive remodelling of dermal tissues as characterized by histological means. The expression of TGF beta 1 was followed for 12 months after irradiation and showed three distinct waves of expression at the RNA level. Levels of expression initially rose to 230% above controls at 6 h before returning to control levels around 24-48 h. Expression then rose again to 169 and 234% above controls at 14 and 28 days post-irradiation respectively. Levels then declined to those of the controls by 2 months. A progressive increase in expression was then noted after 3 months, which peaked around 9 months and was resolved by 12 months. In a parallel study the skin of 144 CBA/ca mice was exposed to 50 Gy superficial beta radiation from 2 x 4 cm Thulium-170 source and compared with a similar group of sham-irradiated controls. The irradiated group showed a cumulative tumour incidence of 54.3% compared with 0% incidence in the sham-irradiated group. Of the 45 radiation-induced tumours a representative sample of 16 (nine malignant fibrous histiocytomas; three fibrosarcomas; two fibromas; one squamous cell carcinoma; one rhabdomyosarcoma) were selected for further study. Semiquantitative PCR on all these tumours showed elevated levels of TGF beta 1 expression ranging from 1.8 to 87-fold above the levels found in normal skin. This study is part of ongoing investigations into the long-term effects of single accidental exposures. The 50 Gy dose used is comparable with the surface doses obtained by some of the victims of the Chernobyl accident.

In vivo cytokine and receptor gene expression during the rat hair growth cycle. Analysis by semi-quantitative RT-PCR

A number of cytokines have previously been localised within the developing and adult hair follicle, however, the role they play in producing a mature hair follicle remains unknown. In an attempt to identify dermal papilla specific cytokines and thus those that may have an important controlling role, cytokine gene expression profiles, obtained by reverse transcriptase-polymerase chain reaction (RT-PCR), were compared between whole anagen rat hair follicles, passage 2 dermal papillae (a cell type with hair inductive capacity), and footpad fibroblasts (a non-hair inducing cell type). Based on this qualitative data, we were unable to identify a dermal papilla specific gene. The analysis of the pattern and timing of cytokine gene expression during the hair cycle is likely to be more informative. A semi-quantitative RT-PCR technique was therefore developed for studying trends in the level of in vivo expression of the following cytokines and their receptors from early anagen to early catagen in the rat hair growth cycle: insulin-like growth factor I, transforming growth factor beta 1, tumour necrosis factor, and basic fibroblast growth factor. These genes were found to be differentially expressed and this was correlated with their possible functions in controlling the hair growth cycle, providing valuable insights into the role of cytokines in regulating the hair growth process.