Hair growth inhibition by psychoemotional stress: a mouse model for neural mechanisms in hair growth control

Autophagy Dysfunction: The Kernel of Hair Loss?

Autophagy is recognized as a crucial regulatory process, instrumental in the removal of senescent, dysfunctional, and damaged cells. Within the autophagic process, lysosomal digestion plays a critical role in the elimination of impaired organelles, thus preserving fundamental cellular metabolic functions and various biological processes. Mitophagy, a targeted autophagic process that specifically focuses on mitochondria, is essential for sustaining cellular health and energy balance. Therefore, a deep comprehension of the operational mechanisms and implications of autophagy and mitophagy is vital for disease prevention and treatment. In this context, we examine the role of autophagy and mitophagy during hair follicle cycles, closely scrutinizing their potential association with hair loss. We also conduct a thorough review of the regulatory mechanisms behind autophagy and mitophagy, highlighting their interaction with hair follicle stem cells and dermal papilla cells. In conclusion, we investigate the potential of manipulating autophagy and mitophagy pathways to develop innovative therapeutic strategies for hair loss.

Role of neurogenic inflammation in the pathogenesis of alopecia areata

Alopecia areata refers to an autoimmune illness indicated by persistent inflammation. The key requirement for alopecia areata occurrence is the disruption of immune-privileged regions within the hair follicles. Recent research has indicated that neuropeptides play a role in the damage to hair follicles by triggering neurogenic inflammation, stimulating mast cells ambient the follicles, and promoting apoptotic processes in keratinocytes. However, the exact pathogenesis of alopecia areata requires further investigation. Recently, there has been an increasing focus on understanding the mechanisms of immune diseases resulting from the interplay between the nervous and the immune system. Neurogenic inflammation due to neuroimmune disorders of the skin system may disrupt the inflammatory microenvironment of the hair follicle, which plays a crucial part in the progression of alopecia areata.

Psychological stress induces hair regenerative disorders through corticotropin-releasing hormone-mediated autophagy inhibition

Psychosocial stress is increasing, causing a growing number of people to suffer from hair loss. Stress-related corticotropin-releasing hormone (CRH) is associated with hair loss, but the mechanism by which hair follicles respond to stress and CRH remain poorly understood. The aim of the study is to elucidate the association between CRH and stress-related hair regenerative disorders, and reveal the potential pathological mechanisms. A chronic unpredictable stress mouse model and a chronic social defeat stress mouse model were used to examine the role of CRH and stress-related hair regrowth. Chronic unpredictable stress and chronic social defeat stress increased the expression of CRH and CRH receptors (CRHRs), and contributed to the onset of hair-cycle abnormalities. Psychoemotional stress and stress-related CRH blocked hair follicle regrowth, which could be restored by astressin, a CRHR antagonist. Long-term exposure to either chronic unpredictable stress or CRH induced a decrease in autophagy, which could be partially rescued by astressin. Activating CRHR, by stress or CRH administration, decreased autophagy via the mTOR-ULK1 signaling pathway to mediate hair regenerative disorders, which could be partially reversed through enhancing autophagy by administration of brefeldin A. These findings indicate that CRH-mediated autophagy inhibition play an important role in stress-induced hair regenerative disorders. CRH regulates the local hypothalamic-pituitary-adrenal axis of hair follicles, but also plays an independent pathogenic role in stress-related hair regenerative disorders through CRH-mediated autophagy inhibition. This work contributes to the present understanding of hair loss and suggests that enhancing autophagy may have a therapeutic effect on stress-induced hair loss.

Exploring clues pointing toward the existence of a brain-gut microbiota-hair follicle axis

Proposing the concept of a brain-gut-skin axis has led some researchers to recognize the relationship among brain activity, gut microbiota, and the skin. Hair follicles are skin accessory organs, a previously unnoticed target tissue for classical neurohormones, neurotrophins, and neuropeptides. Some studies have shown a relationship between the central nervous system and hair follicles that an imbalance in the gut bacteria can affect hair follicle density. This review summarizes existing evidence from literature and explores clues supporting a connection linking the brain, gut microbiota, and hair follicles. It amalgamates previously proposed partial concepts into a new, unified concept-the "brain-gut microbiota-hair follicle" axis, -which suggests that modulation of the microbiome via probiotics can have positive effects on hair follicles. This review also explores how preclinical research on hair follicles can propel novel and clinically untapped applications.

Human Hair Graying Revisited: Principles, Misconceptions, and Key Research Frontiers

Hair graying holds psychosocial importance and serves as an excellent model for studying human pigmentation and aging in an accessible miniorgan. Current evidence suggests that graying results from an interindividually varying mixture of cumulative oxidative and DNA damage, excessive mTORC1 activity, melanocyte senescence, and inadequate production of pigmentation-promoting factors in the hair matrix. Various regulators modulate this process, including genetic factors (DNA repair defects and IRF4 sequence variation, peripheral clock genes, P-cadherin signaling, neuromediators, HGF, KIT ligand secretion, and autophagic flux. This leads to reduced MITF- and tyrosinase-controlled melanogenesis, defective melanosome transfer to precortical matrix keratinocytes, and eventual depletion of hair follicle (HF) pigmentary unit (HFPU) melanocytes and their local progenitors. Graying becomes irreversible only when bulge melanocyte stem cells are also depleted, occurring later in this process. Distinct pigmentary microenvironments are created as the HF cycles: early anagen is the most conducive phase for melanocytic reintegration and activation, and only during anagen can the phenotype of hair graying and repigmentation manifest, whereas the HFPU disassembles during catagen. The temporary reversibility of graying is highlighted by several drugs and hormones that induce repigmentation, indicating potential target pathways. We advise caution in directly applying mouse model concepts, define major open questions, and discuss future human antigraying strategies.

Evaluation of efficacy of Silybum marianum flower extract on the mitigating hair loss in vitro and in vivo

BACKGROUND

Natural components that can exert a wide range of anti-hair loss activity with fewer side effects are in high demand. The objective of this study was to investigate the anti-hair loss potential of Silybum marianum flower extract (SMFE) in vitro and in vivo.

METHODS

The effect of SMFE on dermal papilla cells was evaluated by measuring cell proliferation and VEGF production in hair follicle dermal papilla cells (HFDPCs). In addition, to confirm the effect of SMFE on dermal papilla senescence, SA-β-gal staining and senescence associated secretory phenotype (SASP) production such as IL-6 was observed in both replicative and hydrogen peroxide (H2 O2 )-induced senescence models. In a clinical study, hair growth was determined by reconstitution analysis after shaving the hair of the clinical subject's scalp and hair area.

RESULTS

SMFE increased the proliferation and VEGF production of HFDPCs. It also suppressed cellular senescence of HFDPCs and IL-6 production in replicative senescence and oxidative stress-induced senescence models. The hair density and total hair count at 16 and 24 weeks after using hair shampoo containing SMFE were significantly increased compared with those of the placebo group.

CONCLUSION

SMFE has the potential to be used as a natural ingredient for alleviating hair loss.

Role of stress in skin diseases: A neuroendocrine-immune interaction view

Psychological stress is a crucial factor in the development of many skin diseases, and the stigma caused by skin disorders may further increase the psychological burden, forming a vicious cycle of psychological stress leading to skin diseases. Therefore, understanding the relationship between stress and skin diseases is necessary. The skin, as the vital interface with the external environment, possesses its own complex immune system, and the neuroendocrine system plays a central role in the stress response of the body. Stress-induced alterations in the immune system can also disrupt the delicate balance of immune cells and inflammatory mediators in the skin, leading to immune dysregulation and increased susceptibility to various skin diseases. Stress can also affect the skin barrier function, impair wound healing, and promote the release of pro-inflammatory cytokines, thereby exacerbating existing skin diseases such as psoriasis, atopic dermatitis, acne, and urticaria. In the present review, we explored the intricate relationship between stress and skin diseases from a neuroendocrine-immune interaction perspective. We explored the occurrence and development of skin diseases in the context of stress, the stress models for skin diseases, the impact of stress on skin function and diseases, and relevant epidemiological studies and clinical trials. Understanding the relationship between stress and skin diseases from a neuroendocrine-immune interaction perspective provides a comprehensive framework for targeted interventions and new insights into the diagnosis and treatment of skin diseases.

Integrated transcriptomic and metabolomic investigation of the genes and metabolites involved in swine follicular cyst formation

Follicular cysts are a common reproductive disorder in mammals that is usually caused by stress. However, the pathogenesis of follicular cysts in sows remains unclear. To provide new insights into the mechanisms of follicular cyst formation in pigs, we conducted a combined transcriptomic and metabolomic analysis on theca interna and mural granulosa cells of follicular cysts and mature follicles. We identified 2,533 up-regulated and 1,355 down-regulated genes in follicular cysts, compared with mature follicles. These differentially expressed genes were mainly found in signaling pathways related to tumor formation and cortisol synthesis and secretion as shown by Ingenuity Pathway Analysis, which predicted 4,362 upstream regulatory factors. The combined gene expression and pathway analysis identified the following genes as potential biomarkers for porcine follicular cysts: cytochrome P450 family 2 subfamily C polypeptide 18, L-lactate dehydrogenase, carbamoyl-phosphate synthase, fibroblast growth factor 7, integrin binding sialoprotein, interleukin 23 receptor, prolactin receptor, epiregulin, interleukin 1 receptor type II, arginine vasopressin receptor 1A, fibroblast growth factor 10, claudin 7, G Protein Subunit Gamma 3, cholecystokinin B receptor and cytosolic phospholipase A2. Metabolomics analysis found significant differences in 87 metabolites, which were enriched in unsaturated fatty acid biosynthesis, and sphingolipid signaling pathways. These results provide valuable information on the molecular mechanisms of follicular cyst formation, which may facilitate the development of new therapeutics to prevent and treat follicular cysts.

Neurotensin counteracts hair growth inhibition induced by chronic restraint stress

Stress has been considered as a potential trigger for hair loss through the neuroendocrine-hair follicle (HF) axis. Neurotensin (NTS), a neuropeptide, is known to be dysregulated in the inflammatory-associated skin diseases. However, the precise role of NTS in stress-induced hair loss is unclear. To investigate the function and potential mechanisms of NTS in stress-induced hair growth inhibition, we initially detected the expression of neurotensin receptor (Ntsr) and NTS in the skin tissues of stressed mice by RNA-sequencing and ELISA. We found chronic restraint stress (CRS) significantly decreased the expression of both NTS and Ntsr in the skin tissues of mice. Intracutaneous injection of NTS effectively counteracted CRS-induced inhibition of hair growth in mice. Furthermore, NTS regulated a total of 1093 genes expression in human dermal papilla cells (HDPC), with 591 genes being up-regulated and 502 genes being down-regulated. GO analysis showed DNA replication, cell cycle, integral component of plasma membrane and angiogenesis-associated genes were significantly regulated by NTS. KEGG enrichment demonstrated that NTS also regulated genes related to the Hippo signalling pathway, axon guidance, cytokine-cytokine receptor interaction and Wnt signalling pathway in HDPC. Our results not only uncovered the potential effects of NTS on stress-induced hair growth inhibition but also provided an understanding of the mechanisms at the gene transcriptional level.

Telogen effluvium: a 360 degree review

Telogen effluvium (TE) is one of the most common presentations of diffuse non-cicatricial alopecia and is generally self-limited. Multiple causes are associated with TE onset and its maintenance, with stress being felt the most common factor. The multifactorial etiologies involved in TE makes it a complex disorder to diagnose and treat often placing this entity into a "waste basket" diagnosis. By critically assessing the available scientific literature we aimed to review the multifaceted aspects of TE. Our objectives were to review the pathogenesis with the role of stress (including Coronavirus 19-associated TE), as well as to describe the main clinical findings, its differential diagnosis and the current knowledge on TE treatments along with the future treatment's insights.

Basic principles of hair follicle structure, morphogenesis, and regeneration

Diseases affecting the hair follicle are common in domestic animals, but despite the importance of an intact skin barrier and a fully functional hair coat, knowledge about the detailed morphological features and the diversity of these complex mini-organs are often limited, although mandatory to evaluate skin biopsies with a history of alopecia. The factors that regulate the innate hair follicle formation and the postnatal hair cycle are still not completely understood in rodents, only rudimentarily known in humans, and are poorly understood in our companion animals. This review aims to summarize the current knowledge about hair follicle and hair shaft anatomy, the arrangement of hair follicles, hair follicle morphogenesis in the embryo, and the lifelong regeneration during the postnatal hair cycle in domestic animals. The role of follicular stem cells and the need for a multitude of interacting signaling events during hair follicle morphogenesis and regeneration is unquestioned. Because of the lack of state of the art methods that can be applied in rodents but are not feasible in companion animals, most of the information in this review is based on rodent studies. However, the few data from domestic animals that are available will be discussed, and it can be assumed that at least the principal molecular mechanisms are similar in rodents and other species.

Canine noninflammatory alopecia: An approach to its classification and a diagnostic aid

Noninflammatory alopecia is common in dogs and is a frequent cause to consult a veterinarian. It is also a common reason to take biopsies. Noninflammatory alopecia can be attributed to a decreased formation or cytodifferentiation of the hair follicle or the hair shaft in utero, resulting in congenital alopecia. Congenital alopecia often has a hereditary cause, and examples of such disorders are ectodermal dysplasias associated with gene variants of the ectodysplasin A gene. Noninflammatory alopecia may also be caused by impaired postnatal regeneration of hair follicles or shafts. Such disorders may have a clear breed predilection, and alopecia starts early in life. A hereditary background is suspected in those cases but has not been proven. They are referred to as follicular dysplasia although some of these disorders present histologically like a hair cycle disturbance. Late-onset alopecia is usually acquired and may be associated with endocrinopathies. Other possible causes are impaired vascular perfusion or stress. As the hair follicle has limited possible responses to altered regulation, and histopathology may change during the course of a disease, a detailed clinical history, thorough clinical examination including blood work, appropriate biopsy site selection, and detailed histological findings need to be combined to achieve a final diagnosis. This review aims to provide an overview about the known noninflammatory alopecic disorders in dogs. As the pathogenesis of most disorders is unknown, some statements are based on comparative aspects or reflect the authors' opinion.

Transcriptome analysis reveals genes associated with wool fineness in merinos

Hair/wool usually plays an important role in maintaining animal physiological activities, and the economic value of wool cannot be ignored. At present, people set higher demands on wool fineness. Hence, improving wool fineness is the concern of fine wool sheep breeding. Using RNA-Seq to screen the potential candidate genes that associate with wool fineness can provide theoretical references for fine-wool sheep breeding, and also provide us new ideas for further understand the molecular regulation mechanism of hair growth. In this study, we compared the expression pattern difference of genome-wide genes between the skin transcriptomes of Subo and Chinese Merinos. The results showed that, 16 candidate differentially expressed genes (DEGs) (Included: CACNA1S, GP5, LOC101102392, HSF5, SLITRK2, LOC101104661, CREB3L4, COL1A1, PTPRR, SFRP4, LOC443220, COL6A6, COL6A5, LAMA1, LOC114115342 and LOC101116863 genes) that may associate with wool fineness were screened, and these genes were located in signaling pathways that regulate hair follicle development, cycle or hair growth. It is worth noting that, among the 16 DEGs, COL1A1 gene has the highest expression level in Merino skins, and the fold change of LOC101116863 gene is the highest, and the structures of these two genes are both highly conserved in different species. In conclusion, we speculate that these two genes may play a key role in regulating wool fineness and respectively have similar and conserved functions in different species.

Endocannabinoid and perceived stress: Association analysis of endocannabinoid levels in hair versus levels in plasma and urine

The endocannabinoid system is considered to play a role in a wide range of functions, including stress. Hair analysis of endocannabinoids presents a promising methodological advancement for the retrospective assessment of long-term cumulative endocannabinoid secretion. Despite promising pilot study results suggesting the usefulness of hair endocannabinoid assessments, it remains unclear whether hair endocannabinoid levels mirror systemic endocannabinoid levels accurately. Two independent studies were conducted to investigate to what extent hair endocannabinoid and N-Acylethanolamine levels reflect the systemic levels retrospectively. Endocannabinoid and N-Acylethanolamine levels were measured in 3 cm and 1 cm hair segments respectively, and compared with the averaged levels in multiple plasma samples collected during three months (Study I), and in multiple 24-hour urine samples collected over a month (Study II). In addition, the Perceived Stress Scale was used to assess the perceived stress throughout the studies. Against our hypothesis, no association was found between the endocannabinoid or N-Acylethanolamine levels in hair and plasma or urine. However, hair palmitoylethanolamide (PEA), oleoylethanolamide (OEA), and stearoylethanolamide (SEA) levels were positively correlated with perceived stress in Study I. The current findings suggest that hair endocannabinoid or N-Acylethanolamine levels might not accurately reflect the levels of peripheral circulating endocannabinoid or N-Acylethanolamine. Nevertheless, hair N-Acylethanolamine levels might emerge as a useful strategy in the study of some psychological phenotypes, such as stress.

Effects of Cudrania tricuspidata and Sargassum fusiforme extracts on hair growth in C57BL/6 mice

BACKGROUND

Cudrania tricuspidata is a perennial plant, and Sargassum fusiforme is a brown seaweed with numerous potential benefits, including anticancer, anti-inflammatory, and antioxidant activities. However, the efficacies of C. tricuspidata and S. fusiforme on hair growth have not yet been elucidated. Therefore, the present study examined the effects of C. tricuspidata and S. fusiforme extracts on hair growth in C57BL/6 mice.

RESULTS

ImageJ demonstrated that drinking and skin application of C. tricuspidata and/or S. fusiforme extracts significantly increased the hair growth rate in the dorsal skin of C57BL/6 mice compared to the control group. Histological analysis confirmed that drinking and skin application of C. tricuspidata and/or S. fusiforme extracts for 21 days significantly increased the length of hair follicles on the dorsal skin of treated C57BL/6 mice compared to that in the control mice. RNA sequencing analysis revealed that hair growth cycle-related factors (anagen factors) such as Catenin Beta 1 (Ctnnb1) and platelet-derived growth factor (Pdgf) were upregulated (> twofold) only by C. tricuspidate extracts, whereas vascular endothelial growth factor (Vegf) and Wnts were upregulated by both C. tricuspidata or S. fusiforme applications in treated mice (compared to the control mice). In addition, oncostatin M (Osm, a catagen-telogen factor) was downregulated (< 0.5 fold) by C. tricuspidata when administered via both skin and drinking mode in treated mice compared to that in control mice.

CONCLUSIONS

Our results suggest that C. tricuspidata and/or S. fusiforme extracts show potential hair growth efficacy by upregulating anagen factor genes, including β-catenin, Pdgf, Vegf, and Wnts, and downregulating catagen-telogen factor genes, including Osm, in C57BL/6 mice. The findings suggest that C. tricuspidata and/or S. fusiforme extracts are potential drug candidates to treat alopecia.

Systematic Review of Psychological Interventions for Quality of Life, Mental Health, and Hair Growth in Alopecia Areata and Scarring Alopecia

Alopecia is associated with significant psychological burden. There is limited evidence on the use of psychological interventions in conditions of hair loss. This manuscript systematically reviews the current state of literature on psychological treatments for quality of life, mental health, and hair growth in various forms of alopecia. PubMed and Embase were searched with predefined inclusion and exclusion criteria. Reference lists were also examined for relevant studies. Nine articles met our criteria and are included in this review. Eight of the articles related to alopecia areata and one related to scarring alopecia. Mindfulness-based stress reduction (MBSR) was found to improve quality of life-related subjective symptoms, relationship impacts, anxiety, phobia, distress, and psychological symptom intensity. Alopecia-specific collocated behavioral health (CLBH) treatment showed a trend for psychosocial improvement in areas such as appearance shame, activity avoidance, negative emotions, and coping. Hypnotherapy was found to improve anxiety and depression, quality of life measures, and alexithymia. There was also some evidence for significant hair growth with hypnosis, but the data are mixed. Psychotherapy combined with immunotherapy led to more hair growth, and supported self-confidence. Finally, coping strategies modulated the subjective burden of alopecia, and were associated with disease improvement. Further research will be necessary to better establish the efficacy and optimal administration of these interventions in alopecia.

Chronotype and insomnia may affect the testosterone levels with a sexual difference: a Mendelian randomization

OBJECTIVE

To evaluate the causal effects of sleep traits (i.e., chronotype, insomnia, and sleep duration) on bioavailable testosterone (BT), sex hormone-binding globulin (SHBG), and total testosterone (TT) levels in women and men.

METHODS

We performed Mendelian randomization (MR) using random-effect inverse-variance weighted (IVW) and 7 other MR analyses. Exposure data for sleep traits were obtained from the largest-to-date genome-wide association study (GWAS) from 339,926 to 1,331,010 individuals. Summary data for testosterone levels were obtained from GWAS based on the UK Biobank.

RESULTS

For women, our study supported that chronotype was associated with decreased BT (IVW: β = - 0.042, 95% CI - 0.060, - 0.023, p = 1.17E-05) and TT (IVW: - 0.053, 95% CI - 0.075, - 0.031, p = 2.30E-06). Besides, insomnia can significantly increase BT (IVW: β = 0.025, 95% CI 0.009, 0.041, p = 0.002). These findings were significant in most sensitivity analyses. For men, statistical significance was found between chronotype and BT (β = - 0.027, 95% CI - 0.048, - 0.005, p = 0.016), and insomnia and TT (β = - 0.028, 95% CI - 0.049, 0.007, p = 0.009) in IVW. However, the effect estimates were not broadly consistent with other sensitivity analyses. Our study did not find support for causal effects of sleep duration on testosterone levels in both women and men.

CONCLUSION

Our study reveals the sex differences in the effects of sleep traits on testosterone levels. A healthy sleep habit is vital for the maintenance of testosterone homeostasis in women. Further studies are warranted to investigate the associations between sleep traits and testosterone levels in men.

The impact of perceived stress on the hair follicle: Towards solving a psychoneuroendocrine and neuroimmunological puzzle

While popular belief harbors little doubt that perceived stress can cause hair loss and premature graying, the scientific evidence for this is arguably much thinner. Here, we investigate whether these phenomena are real, and show that the cyclic growth and pigmentation of the hair follicle (HF) provides a tractable model system for dissecting how perceived stress modulates aspects of human physiology. Local production of stress-associated neurohormones and neurotrophins coalesces with neurotransmitters and neuropeptides released from HF-associated sensory and autonomic nerve endings, forming a complex local stress-response system that regulates perifollicular neurogenic inflammation, interacts with the HF microbiome and controls mitochondrial function. This local system integrates into the central stress response systems, allowing the study of systemic stress responses affecting organ function by quantifying stress mediator content of hair. Focusing on selected mediators in this "brain-HF axis" under stress conditions, we distill general principles of HF dysfunction induced by perceived stress.

Heat-Killed Enterococcus faecalis EF-2001 Induces Human Dermal Papilla Cell Proliferation and Hair Regrowth in C57BL/6 Mice

Minoxidil is the most widely used treatment for hair growth, but has been associated with several side effects. In this study, we investigated the effects of heat-killed Enterococcus faecalis EF-2001 on hair loss prevention and regrowth using human dermal papilla cells and male C57BL/6 mice. To examine the effects of EF-2001, we used minoxidil as the positive control. In the in vitro experiments, EF-2001 treatment (75-500 μg/mL) led to the proliferation of human dermal papilla cells in a concentration-dependent manner. In the in vivo experiment, the topical application of 200 µL EF-2001 on the dorsal surface of C57BL/6 male mice led to hair growth. Changes in hair regrowth were examined by visual comparison and hematoxylin and eosin staining of skin sections. We also determined the expression levels of marker genes (Wnt) and growth factors (fibroblast growth factor, insulin growth factor 1, and vascular endothelial growth factor) in the skin tissues of the back of each mouse using a quantitative polymerase chain reaction. EF-2001 accelerated the progression of hair regrowth in mice and promoted hair-follicle conversion from telogen to anagen, likely by increasing the expression levels of growth factors and marker genes.

Integrated Transcriptomics and Metabolomics Analyses of Stress-Induced Murine Hair Follicle Growth Inhibition

Psychological stress plays an important role in hair loss, but the underlying mechanisms are not well-understood, and the effective therapies available to regrow hair are rare. In this study, we established a chronic restraint stress (CRS)-induced hair growth inhibition mouse model and performed a comprehensive analysis of metabolomics and transcriptomics. Metabolomics data analysis showed that the primary and secondary metabolic pathways, such as carbohydrate metabolism, amino acid metabolism, and lipid metabolism were significantly altered in skin tissue of CRS group. Transcriptomics analysis also showed significant changes of genes expression profiles involved in regulation of metabolic processes including arachidonic acid metabolism, glutathione metabolism, glycolysis gluconeogenesis, nicotinate and nicotinamide metabolism, purine metabolism, retinol metabolism and cholesterol metabolism. Furthermore, RNA-Seq analyses also found that numerous genes associated with metabolism were significantly changed, such as Hk-1, in CRS-induced hair growth inhibition. Overall, our study supplied new insights into the hair growth inhibition induced by CRS from the perspective of integrated metabolomics and transcriptomics analyses.

The Effect of Botulinum Toxin on Hair Follicle Cell Regeneration Under Continuous Stress Conditions: a Pilot Animal Study

We analyzed the effect of botulinum toxin (BTX) type A on the regeneration of hair follicle cells under continuous stress conditions. Thirty 6-week-old C57BL/6 mice were used, and hair loss was induced on their backs (10 control (CTL) mice, reared under normal conditions without stress; 10 mice, exposed to continuous stress (STRESS) by fixing in an enclosed space; 10 BTX + STRESS mice, injected subcutaneously with 1 IU of BTX (0.1 cc) where the hair follicles were removed under the same stress conditions). There was less hair growth in the STRESS and BTX + STRESS groups compared to that in the CTL group at 2 weeks. At 3 weeks, the telogen stage was mainly observed in the STRESS group whereas the anagen stage was observed in the CTL and BTX + STRESS groups. A substantial increase in terminal deoxynucleotidyl transferase dUTP nick end labeling-positive cells was observed in the STRESS group compared to that in the CTL and BTX + STRESS groups. Substance P (SP) immunoreactivity cell levels increased in the STRESS group at 2 and 3 weeks compared to those in the BTX + STRESS group. SP expression increased at 2 and 3 weeks in the STRESS group compared to that in the CTL and BTX + STRESS groups. A delay in the regeneration cycle of the hair follicle cells occurred when stress was applied, and an almost normal regeneration cycle occurred when BTX was injected subcutaneously. Therefore, BTX may be a positive indicator for hair loss treatment.

Autophagy protects murine preputial glands against premature aging, and controls their sebum phospholipid and pheromone profile

Preputial glands are large lipid and hormone secreting sebaceous organs of mice, and present a convenient model for the investigation of biological processes in sebocytes. Suppression of ATG7-dependent macroautophagy/autophagy in epithelial cells of murine skin causes enlargement of hair follicle-associated sebaceous glands and alters the lipid profile of sebum. We have now extended these studies to the preputial glands and find that autophagy significantly delays the onset of age-related ductal ectasia, influences lipid droplet morphology and contributes to the complete dissolution of the mature sebocytes during holocrine secretion. Single cell RNA sequencing showed that many genes involved in lipid metabolism and oxidative stress response were downregulated in immature and mature epithelial cells of ATG7-deficient glands. When analyzing the lipid composition of control and mutant glands, we found that levels of all phospholipid classes, except choline plasmalogen, were decreased in the mutant glands, with a concomitant accumulation of diacyl glycerides. Mass spectrometric imaging (MSI) demonstrated that phospholipid species, specifically the dominant phosphatidylcholine (PC 34:1), were decreased in immature and mature sebocytes. In addition, we found a strong reduction in the amounts of the pheromone, palmityl acetate. Thus, autophagy in the preputial gland is not only important for homeostasis of the gland as a whole and an orderly breakdown of cells during holocrine secretion, but also regulates phospholipid and fatty acid metabolism, as well as pheromone production.AbbreviationsATG7: autophagy related 7; BODIPY: boron dipyrromethene; DAG: diacyl glycerides; DBI: diazepam binding inhibitor; GFP: green fluorescent protein; KRT14: keratin 14; HPLC-MS: high performance liquid chromatography-mass spectrometry; LD: lipid droplet; MAP1LC3/LC3: microtubule-associated protein 1 light chain 3; MSI: mass spectrometric imaging; ORO: Oil Red O; PC: phosphatidylcholine; PE: phosphatidylethanolamine; PG: preputial gland; PLIN2: perilipin 2; PtdIns: phosphatidylinositol; PL: phospholipids; POPC: 1-palmitoyl-2-oleoyl-PC; PS: phosphatidylserine; qRT-PCR: quantitative reverse transcribed PCR; SG: sebaceous gland; scRNAseq: single-cell RNA sequencing; TAG: triacylglycerides; TLC: thin layer chromatography.

Hair growth predicts a depression-like phenotype in rats as a mirror of stress traceability

As a subjective mood-related disorder with an unclear mechanism, depression has many problems in its diagnosis, which offers great space and value for research. At present, the methods commonly used to judge whether an animal model of depression has been established are mainly by biochemical index detection and behavioral tests, both of which inevitably cause stress in animals. Stress-induced hair growth inhibition has been widely reported in humans and animals. The simplicity of collecting hair samples and the observable state of hair growth has significant advantages; we tried to explore whether the parameters related to hair growth could be used as auxiliary indicators to evaluate a depression model in animals. The length and weight of the hair were calculated. Correlation analysis was conducted between the depressive behavioral results and the glucocorticoid levels in hair and serum. Learned helplessness combined with chronic restraint stress, and chronic unpredictable stress in the animal were detectable by superficial observation, weight ratio, and length of hair, and follicular development scores were significantly reduced compared to the control. The hair growth parameters of rats with depression, the rise in corticosterone, and the corresponding changes in behavioral parameters were significantly correlated. The neurotrophic factors, glucocorticoid-receptor (GR), brain-derived neurotrophic factor (BDNF), fibroblast growth factor 2 (FGF2), and fibroblast growth factor 5 (FGF5), are associated with depression and hair growth. Significant differences were detected between the stress and control groups, suggesting that the mechanism underlying the stress-phenomenon inhibition of hair growth may be related to growth factor mediation.

Understanding Causes of Hair Loss in Women

Hair loss affects millions of people worldwide and can have devastating effects on an individual's psychoemotional well-being. Today hair restoration technologies through hair transplantation have advanced with the use of robots and follicular unit extraction and grafting that it is possible to offer to patient's excellent clinical results. Adjuvant modalities such as platelet-rich plasma injections, lasers, and stem cells can further enhance the durability, health, and appearance of hair transplants.

Current views on neuropeptides in atopic dermatitis

Atopic dermatitis (AD) is a chronic inflammatory skin disease involving skin barrier dysfunction and immune imbalance. However, the mechanism of AD is not clear completely and may be related to heredity and environment. Neuropeptides are a class of peptides secreted by nerve endings, they may play roles in promoting vasodilation, plasma extravasation, chemotaxis of inflammatory cells and mediating pruritus. Since itching and immune cell infiltration are the main manifestations of atopic dermatitis, to further investigate the impact of neuropeptides on AD, our review summarized the mechanisms of several common neuropeptides in AD and hypothesized that neuropeptides may be the novel potential targets in AD treatment.

New Pathways for the Skin's Stress Response: The Cholinergic Neuropeptide SLURP-1 Can Activate Mast Cells and Alter Cytokine Production in Mice

Background: The alpha7 nicotinic acetylcholine receptor (Chrna7) plays an essential anti-inflammatory role in immune homeostasis and was recently found on mast cells (MC). Psychosocial stress can trigger MC hyperactivation and increases pro-inflammatory cytokines in target tissues such as the skin. If the cholinergic system (CS) and Chrna7 ligands play a role in these cascades is largely unknown.

Objective: To elucidate the role of the CS in the response to psychosocial stress using a mouse-model for stress-triggered cutaneous inflammatory circuits.

Methods: Key CS markers (ACh, Ch, SLURP-1, SLURP-2, Lynx1, Chrm3, Chrna7, Chrna9, ChAT, VAChT, Oct3, AChE, and BChE) in skin and its MC (sMC), MC activation, immune parameters (TNFα, IL1β, IL10, TGFβ, HIF1α, and STAT3) and oxidative stress were analyzed in skin from 24 h noise-stressed mice and in cultured MC (cMC) from C57BL/6 or Chrna7-Knockout mice.

Results: First, Chrna7 and SLURP-1 mRNA were exclusively upregulated in stressed skin. Second, histomorphometry located Chrna7 and SLURP-1 in nerves and sMC and demonstrated upregulated contacts and increased Chrna7+ sMC in stressed skin, while 5 ng/mL SLURP-1 degranulated cMC. Third, IL1β+ sMC were high in stressed skin, and while SLURP-1 alone had no significant effect on cMC cytokines, it upregulated IL1β in cMC from Chrna7-KO and in IL1β-treated wildtype cMC. In addition, HIF1α+ sMC were high in stressed skin and Chrna7-agonist AR-R 17779 induced ROS in cMC while SLURP-1 upregulated TNFα and IL1β in cMC when HIF1α was blocked.

Conclusions: These data infer that the CS plays a role in the regulation of stress-sensitive inflammatory responses but may have a surprising pro-inflammatory effect in healthy skin, driving IL1β expression if SLURP-1 is involved.

Mouse models of atopic dermatitis: a critical reappraisal

Mouse models for atopic dermatitis (AD) are an indispensable preclinical research tool for testing new candidate AD therapeutics and for interrogating AD pathobiology in vivo. In this Viewpoint, we delineate why, unfortunately, none of the currently available so-called "AD" mouse models satisfactorily reflect the clinical complexity of human AD, but imitate more "allergic" or "irriant" contact dermatitis conditions. This limits the predictive value of AD models for clinical outcomes of new tested candidate AD therapeutics and the instructiveness of mouse models for human AD pathophysiology research. Here, we propose to initiate a rational debate on the minimal criteria that a mouse model should meet in order to be considered relevant for human AD. We suggest that valid AD models should at least meet the following criteria: (a) an AD-like epidermal barrier defect with reduced filaggrin expression along with hyperproliferation, hyperplasia; (b) increased epidermal expression of thymic stromal lymphopoietin (TSLP), periostin and/or chemokines such as TARC (CCL17); (c) a characteristic dermal immune cell infiltrate with overexpression of some key cytokines such as IL-4, IL-13, IL-31 and IL-33; (d) distinctive "neurodermatitis" features (sensory skin hyperinnervation, defective beta-adrenergic signalling, neurogenic skin inflammation and triggering or aggravation of AD-like skin lesions by perceived stress); and (e) response of experimentally induced skin lesions to standard AD therapy. Finally, we delineate why humanized AD mouse models (human skin xenotransplants on SCID mice) offer a particularly promising preclinical research alternative to the currently available "AD" mouse models.

New effects of caffeine on corticotropin-releasing hormone (CRH)-induced stress along the intrafollicular classical hypothalamic-pituitary-adrenal (HPA) axis (CRH-R1/2, IP3 -R, ACTH, MC-R2) and the neurogenic non-HPA axis (substance P, p75NTR and TrkA) in ex vivo human male androgenetic scalp hair follicles

BACKGROUND

Human hair is highly responsive to stress, and human scalp hair follicles (HFs) contain a peripheral neuroendocrine equivalent of the systemic hypothalamic-pituitary-adrenal (HPA) stress axis. Androgenetic alopecia (AGA) is supposed to be aggravated by stress. We used corticotropin-releasing hormone (CRH), which triggers the HPA axis, to induce a stress response in human ex vivo male AGA HFs. Caffeine is known to reverse testosterone-mediated hair growth inhibition in the same hair organ culture model.

OBJECTIVES

To investigate whether caffeine would antagonize CRH-mediated stress in these HFs.

METHODS

HFs from balding vertex area scalp biopsies of men affected by AGA were incubated with CRH (10-7 mol L-1 ) with or without caffeine (0·001% or 0·005%).

RESULTS

Compared to controls, CRH significantly enhanced the expression of catagen-inducing transforming growth factor-β2 (TGF-β2) (P < 0·001), CRH receptors 1 and 2 (CRH-R1/2) (P < 0·01), adrenocorticotropic hormone (ACTH) (P < 0·001) and melanocortin receptor 2 (MC-R2) (P < 0·001), and additional stress-associated parameters, substance P and p75 neurotrophin receptor (p75NTR ). CRH inhibited matrix keratinocyte proliferation and expression of anagen-promoting insulin-like growth factor-1 (IGF-1) and the pro-proliferative nerve growth factor receptor NGF-tyrosine kinase receptor A (TrkA). Caffeine significantly counteracted all described stress effects and additionally enhanced inositol trisphosphate receptor (IP3 -R), for the first time detected in human HFs.

CONCLUSIONS

These findings provide the first evidence in ex vivo human AGA HFs that the stress mediator CRH induces not only a complex intrafollicular HPA response, but also a non-HPA-related stress response. Moreover, we show that these effects can be effectively antagonized by caffeine. Thus, these data strongly support the hypothesis that stress can impair human hair physiology and induce hair loss, and that caffeine may effectively counteract stress-induced hair damage and possibly prevent stress-induced hair loss.

The biology of human hair greying

Hair greying (canities) is one of the earliest, most visible ageing-associated phenomena, whose modulation by genetic, psychoemotional, oxidative, senescence-associated, metabolic and nutritional factors has long attracted skin biologists, dermatologists, and industry. Greying is of profound psychological and commercial relevance in increasingly ageing populations. In addition, the onset and perpetuation of defective melanin production in the human anagen hair follicle pigmentary unit (HFPU) provides a superb model for interrogating the molecular mechanisms of ageing in a complex human mini-organ, and greying-associated defects in bulge melanocyte stem cells (MSCs) represent an intriguing system of neural crest-derived stem cell senescence. Here, we emphasize that human greying invariably begins with the gradual decline in melanogenesis, including reduced tyrosinase activity, defective melanosome transfer and apoptosis of HFPU melanocytes, and is thus a primary event of the anagen hair bulb, not the bulge. Eventually, the bulge MSC pool becomes depleted as well, at which stage greying becomes largely irreversible. There is still no universally accepted model of human hair greying, and the extent of genetic contributions to greying remains unclear. However, oxidative damage likely is a crucial driver of greying via its disruption of HFPU melanocyte survival, MSC maintenance, and of the enzymatic apparatus of melanogenesis itself. While neuroendocrine factors [e.g. alpha melanocyte-stimulating hormone (α-MSH), adrenocorticotropic hormone (ACTH), ß-endorphin, corticotropin-releasing hormone (CRH), thyrotropin-releasing hormone (TRH)], and micropthalmia-associated transcription factor (MITF) are well-known regulators of human hair follicle melanocytes and melanogenesis, how exactly these and other factors [e.g. thyroid hormones, hepatocyte growth factor (HGF), P-cadherin, peripheral clock activity] modulate greying requires more detailed study. Other important open questions include how HFPU melanocytes age intrinsically, how psychoemotional stress impacts this process, and how current insights into the gerontobiology of the human HFPU can best be translated into retardation or reversal of greying.

The local hypothalamic-pituitary-adrenal axis in cultured human dermal papilla cells

BACKGROUND

Stress is an important cause of skin disease, including hair loss. The hormonal response to stress is due to the HPA axis, which comprises hormones such as corticotropin releasing factor (CRF), adrenocorticotropic hormone (ACTH), and cortisol. Many reports have shown that CRF, a crucial stress hormone, inhibits hair growth and induces hair loss. However, the underlying mechanisms are still unclear. The aim of this study was to examine the effect of CRF on human dermal papilla cells (DPCs) as well as hair follicles and to investigate whether the HPA axis was established in cultured human DPCs.

RESULTS

CRF inhibited hair shaft elongation and induced early catagen transition in human hair follicles. Hair follicle cells, both human DPCs and human ORSCs, expressed CRF and its receptors and responded to CRF. CRF inhibited the proliferation of human DPCs through cell cycle arrest at G2/M phase and induced the accumulation of reactive oxygen species (ROS). Anagen-related cytokine levels were downregulated in CRF-treated human DPCs. Interestingly, increases in proopiomelanocortin (POMC), ACTH, and cortisol were induced by CRF in human DPCs, and antagonists for the CRF receptor blocked the effects of this hormone.

CONCLUSION

The results of this study showed that stress can cause hair loss by acting through stress hormones. Additionally, these results suggested that a fully functional HPA axis exists in human DPCs and that CRF directly affects human DPCs as well as human hair follicles under stress conditions.

Alcohol extract from Vernonia anthelmintica willd (L.) seed counteracts stress-induced murine hair follicle growth inhibition

BACKGROUND

Vernonia anthelmintica (L.) willd is a traditional urgur herb in China for a long history. Its alcohol extract (AVE) has been proved to promote hair follicle growth in C57BL/6 mice. We conducted this study to investigate the hair-growth effects of AVE in stressed mice and its possible mechanism of action.

METHODS

The hair-follicle growth effects of AVE were examined by in vivo and in vitro study. We exposed C57BL/6 male mice to chronic restraint stress to induce murine hair follicle growth inhibition. The effects of AVE were examined by histological analysis, immunofluorescence for Ki67 and cytokeratin 19 immunoreactivity, western blot assay in tyrosinase and related proteins expressions and immunofluorescence for nerve fibers. In organ culture of mouse vibrissae follicles, we used substance P as a catagen-inducing factor of hair follicle growth, and measured the elongation of hair shafts and expression of neurokinin-1 receptor protein by application of AVE.

RESULTS

Our results showed that AVE counteract murine hair follicle growth inhibition caused by chronic restraint stress via inducing the conversion of telogen to anagen and inhibiting catagen premature, increasing bulb keratinocytes and bulge stem cells proliferation, promoting melanogenesis, and reducing the numbers of substance P and calcitonin gene-related peptide nerve fibers. Furthermore, AVE also counteracted murine hair follicle growth inhibition caused by substance P in organ culture.

CONCLUSION

These results suggest that AVE counteract stress-induced hair follicle growth inhibition in C57BL/6 mice in vivo and in vitro, and may be an effective new candidate for treatment of stress-induced hair loss.

Chronotype, social jetlag and sleep loss in relation to sex steroids

Chronotype describes preferences for functioning at different times of the day. At the onset of puberty, a sharp shift towards eveningness starts, reaching its peak at the end of adolescence, followed by a steady shift towards morningness as the ageing process occurs. Puberty is also the time when sex differences appear, with men being more inclined to eveningness than women, which diminishes around menopause; the described pattern of changes in chronotype leads to the hypothesis that reproductive hormones may be the driving factor behind this conversion. In the present study, we aimed to verify this hypothesis by analysing participants' testosterone, progesterone and dehydroepiandrosterone (DHEA) levels in the three months, as indicated by assays in 3-cm hair strands from the scalp. Participants (n = 239) of both sexes also completed the Munich Chronotype Questionnaire. The results showed that in men higher testosterone levels were related to eveningness and less sleep loss, whereas greater sleep loss was associated with lower levels of DHEA. In women, no associations between chronotype and levels of the analysed hormones were found. The results support the hypothesis that testosterone levels play a role in shaping eveningness. We further hypothesised that a possible cause of the higher secretion level of testosterone in men with the evening chronotype is a mechanism to offset the negative consequences of sleep loss.

Effects of a gintonin-enriched fraction on hair growth: an in vitro and in vivo study

Background

Ginseng has been widely used as a health-promoting tonic. Gintonin present in ginseng acts as a lysophosphatidic acid (LPA) receptor ligand that activates six LPA receptor subtypes. The LPA6 subtype plays a key role in normal hair growth, and mutations in the LPA6 receptor impair normal human hair growth. Currently, human hair loss and alopecia are concerning issues that affect peoples' social and day-to-day lives.

Objective

We investigated the in vitro and in vivo effects of a gintonin-enriched fraction (GEF) on mouse hair growth.

Methods

Human hair follicle dermal papilla cells (HFDPCs) and six-week-old male C57BL/6 mice were used. The mice were divided into the four groups: control, 1% minoxidil, 0.75% GEF, and 1.5% GEF. The dorsal hair was removed to synchronize the telogen phase. Each group was treated topically, once a day, for 15 days. We analyzed hair growth activity and histological changes.

Results

GEF induced transient [Ca²⁺]_i, which stimulated HFDPC proliferation and caused 5-bromo-2'-deoxyuridine (BrdU) incorporation in a concentration-dependent manner. GEF-mediated HFDPC proliferation was blocked by the LPA receptor antagonist and Ca²⁺ chelator. HFDPC treatment with GEF stimulated vascular endothelial growth factor release. Topical application of GEF and minoxidil promoted hair growth in a dose-dependent manner. Histological analysis showed that GEF and minoxidil increased the number of hair follicles and hair weight.

Conclusion

Topical application of GEF promotes mouse hair growth through HFDPC proliferation. GEF could be one of the main components of ginseng that promote hair growth and could be used to treat human alopecia.

Assessment of Brain Derived Neurotrophic Factor in hair to study stress responses: A pilot investigation

To study pathogenic stress-effects in health and disease, it is paramount to define easy access parameters for non-invasive analysis of biological change in response to stress. Hair samples successfully provide this access for the study of hypothalamus-pituitary-adrenal axis (HPA) changes. In this study, we assess the hair expression and corresponding epigenetic changes of a neurotrophin essential for autonomic nervous system function and mental health: brain derived neurotrophic factor (BDNF). In three independent studies in healthy academic volunteers (study I: German students, N=36; study II, German academic population sample, N=28; study III: Mexican students, N=115), BDNF protein expression or BDNF gene (BDNF) histone acetylation was determined. Simultaneously, mental distress and distress-associated somatic complaints were assessed by self-report. In study I, we found a negative correlation between hair-BDNF protein level and hair-cortisol as well as between hair-BDNF and somatic complaints, while hair-cortisol correlated positively with mental distress. In study II, we found a negative correlation between H4 histone acetylation at the BDNF gene P4-promoter and somatic complaints. Regression analysis confirmed confounder stability of associations in both studies. In study III, we confirmed study I and found lower hair-BDNF protein level in volunteers with high somatic complaints, who also reported higher mental distress during the end of term exams. The results indicate that BDNF protein levels can be detected in clipped hair and are associated with somatic complaints and stress in life. In addition, we concluded that plucked hair can provide material for the study of epigenetic changes in stress-affected tissues. These tools can prove valuable for future studies on distress, both under experimental and field conditions.

11β-Hydroxysteroid Dehydrogenase Type 1 Inhibition Attenuates the Adverse Effects of Glucocorticoids on Dermal Papilla Cells

PURPOSE

Glucocorticoids, stress-related hormones, inhibit hair growth. Intracellular glucocorticoid availability is regulated by 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1). 11β-HSD1 was recently detected in keratinocytes and fibroblasts. However, the expression of 11β-HSD1 in human hair follicles remains unknown. We aimed to examine 11β-HSD1 expression in human dermal papilla cells (DPCs) and to investigate whether modulation of 11β-HSD1 activity can regulate the negative effects of glucocorticoids on DPCs.

MATERIALS AND METHODS

11β-HSD1 expression in normal human scalp skin was examined by immunohistochemistry. 11β-HSD1 protein was detected in Western blots of human DPCs. Cultured human DPCs were treated with cortisol with or without a selective 11β-HSD1 inhibitor and subsequently stained for Ki-67 antibody. Expression levels of 11β-HSD1, Wnt5a, alkaline phosphatase (ALP), and vascular endothelial growth factor (VEGF) were analyzed by Western blotting.

RESULTS

11β-HSD1 was detected in dermal papilla in human scalp skin by immunohistochemistry. Human DPCs expressed 11β-HSD1 protein in vitro. Furthermore, cortisol stimulated the expression of 11β-HSD1 in DPCs. Glucocorticoids decreased cellular proliferation and the expression of Wnt5a, ALP, and VEGF in DPCs. A specific 11β-HSD1 inhibitor significantly attenuated the anti-proliferative effects of cortisol and reversed the cortisol-induced suppression of Wnt5a, ALP, and VEGF expression in DPCs.

CONCLUSION

Our data demonstrated the expression of 11β-HSD1 in human DPCs and revealed that inhibition of 11β-HSD1 activity can partially prevent the negative effect of glucocorticoids on DPCs, suggesting the possible application of 11β-HSD1 inhibitors for stress-related hair loss.

Hair and stress: A pilot study of hair and cytokine balance alteration in healthy young women under major exam stress

Mouse models show that experimental stress mimicking prolonged life-stress exposure enhances neurogenic inflammation, induces adaptive immunity cytokine-imbalance characterized by a shift to Type 1 T-helper cell cytokines and increases apoptosis of epithelial cells. This affects hair growth in otherwise healthy animals. In this study, we investigate whether a prolonged naturalistic life-stress exposure affects cytokine balance and hair parameters in healthy humans. 33 (18 exam, 15 comparison) female medical students with comparable sociobiological status were analyzed during a stressful final examination period, at three points in time (T) 12 weeks apart. T1 was before start of the learning period, T2 between the three-day written exam and an oral examination, and T3 after a 12 week rest and recovery from the stress of the examination period. Assessments included: self-reported distress and coping strategies (Perceived Stress Questionnaire [PSQ], Trier Inventory for the Assessment of Chronic Stress [TICS]), COPE), cytokines in supernatants of stimulated peripheral blood mononucleocytes (PBMCs), and trichogram (hair cycle and pigmentation analysis). Comparison between students participating in the final medical exam at T2 and non-exam students, revealed significantly higher stress perception in exam students. Time-wise comparison revealed that stress level, TH1/TH2 cytokine balance and hair parameters changed significantly from T1 to T2 in the exam group, but not the control. However, no group differences were found for cytokine balance or hair parameters at T2. The study concludes that in humans, naturalistic stress, as perceived during participation in a major medical exam, has the potential to shift the immune response to TH1 and transiently hamper hair growth, but these changes stay within a physiological range. Findings are instructive for patients suffering from hair loss in times of high stress. Replication in larger and more diverse sample populations is required, to assess suitability of trichogram analysis as biological outcome for stress studies.

Presence of Mast Cells and Mast Cell Degranulation in Scalp Biopsies of Telogen Effluvium

BACKGROUND

Telogen effluvium (TE) is a type of acquired, diffuse alopecia that occurs due to an abnormal shift of scalp hair follicles from anagen to telogen, leading to premature shedding of hair. Previous studies have suggested the existence of a neuroimmunologic "brain-hair follicle" axis, in which mast cells have been implicated as an important link between the nervous system and immunologic system.

OBJECTIVE

The current study sought to investigate the role of mast cell presence and mast cell degranulation in the pathogenesis of TE.

MATERIALS AND METHODS

Mast cells were counted using Giemsa and tryptase immunohistochemical stains in scalp biopsy specimens with the pathologic diagnosis of TE (TE, n = 10), alopecia areata (AA, n = 7), and androgenic alopecia (ANDRO, n = 9).

RESULTS

We found significant (P < 0.001) group-level differences between the mean mast cell counts per high-power fields for each type of alopecia studied. Tukey post hoc analysis showed the mean mast cell count for TE to be significantly larger than AA for both Giemsa (P = 0.002) and tryptase (P = 0.006); significantly larger than ANDRO for both Giemsa (P < 0.001) and tryptase (P < 0.001); and significantly larger when compared to normal scalp skin for both Giemsa (P < 0.001) and tryptase (P < 0.001). No significant difference of mean mast cell counts was observed for AA compared to ANDRO for Giemsa (P = 0.373) or tryptase (P = 0.598) stains.

CONCLUSION

Our findings suggest that mast cells could play a role in mediating stress-induced hair loss seen in TE.

Acute Stress-Induced Changes in Follicular Dermal Papilla Cells and Mobilization of Mast Cells: Implications for Hair Growth

BACKGROUND

Stress is a known cause of hair loss in many species.

OBJECTIVE

In this study, we investigated the role of acute stress on hair growth using a rat model.

METHODS

Rats were immobilized for 24 hours and blood samples, and skin biopsies were taken. The effect of stress-serum on the in vitro proliferation of rat and human dermal papilla cells (hDPCs), as well as serum cortisol and corticotropin-releasing hormone levels, were measured. Mast cell staining was performed on the biopsied tissue. In addition, Western blot and quantitative real time polymerase chain reaction were used to assess mast cell tryptase and cytokine expression, respectively in rat skin biopsies.

RESULTS

Stress-serum treatment reduced significantly the number of viable hDPCs and arrested the cell cycle in the G1 phase, compared to serum from unrestrained rats (p<0.05, respectively). Moreover, restrained rats had significantly higher levels of cortisol in serum than unrestrained rats (p<0.01). Acute stress serum increased mast cell numbers and mast cell tryptase expression, as well as inducing interleukin (IL)-6 and IL-1β up-regulation.

CONCLUSION

These results suggest that acute stress also has an inhibitory effect on hair growth via cortisol release in addition to substance P-mast cell pathway.

Cornu cervi pantotrichum Pharmacopuncture Solution Facilitate Hair Growth in C57BL/6 Mice

Objectives:

Cornu cervi pantotrichum (CCP) has been widely used in Korean and China, as an anti-fatigue, anti-aging, and tonic agent to enhance the functions of the reproductive and the immune systems. Because CCP has various growth factors that play important roles in the development of hair follicles, we examined whether CCP pharmacopuncture solution (CCPPS) was capable of promoting hair growth in an animal model.

Methods:

One day after hair depilation, CCPPS were topically applied to the dorsal skin of C57BL/6 mice once a day for 15 days. Hair growth activity was evaluated by using macro- and microscopic observations. Dorsal skin tissues were stained with hematoxylin and eosin. Expressions of bromodeoxyuridine (BrdU), proliferating cell nuclear antigen (PCNA), and fibroblast growth factor (FGF)-7 were examined by using immunohistochemical staining. A reverse transcription polymerase chain reaction (RT-PCR) analysis was also conducted to measure the messenger RNA (mRNA) expression of FGF-7.

Results:

CCPPS induced more active hair growth than normal saline. Histologic analysis showed enlargement of the dermal papilla, elongation of the hair shaft, and expansion of hair thickness in CCPPS treated mice, indicating that CCPPS effectively induced the development of anagen. CCPPS treatment markedly increased the expressions of BrdU and PCNA in the hair follicles of C57BL/6 mice. In addition, CCPPS up regulated the expression of FGF-7, which plays an important role in the development of hair follicles.

Conclusion:

These results reveal that CCPPS facilitates hair re-growth by proliferation of hair follicular cells and up-regulation of FGF-7 and suggest that CCPPS can potentially be applied as an alternative treatment for patients with alopecia.

Norepinephrine Regulates Keratinocyte Proliferation to Promote the Growth of Hair Follicles

Psychological factors and stress can cause hair loss. The sympathetic-adrenal-medullary (SAM) axis has been reported to regulate the growth of hair follicles (HF). The sympathetic nerve is a component of the SAM axis, but it has not been sufficiently or convincingly linked to hair growth. In this study, we demonstrate that chemical sympathectomy via administration of the neurotoxin 6-hydroxydopamine (6-OHDA) to mice inhibited HF growth, but treatment with the β-adrenoceptor antagonist propranolol (PR) had no effect. HF length and skin thickness were greater in PR-treated and control mice than in 6-OHDA-treated mice, as evidenced by hematoxylin and eosin staining. Furthermore, we found that the reduced HF growth in sympathectomized animals was accompanied by a decreased keratinocyte proliferation. Moreover, the neurotransmitter norepinephrine (NE) was found to efficiently promote HF growth in an organotypic skin culture model. Together, these findings suggest that sympathetic nerves regulate keratinocyte behaviors to promote hair growth, providing novel insights into stress-related, chemotherapy-, and radiotherapy-induced alopecia.

Frontal Fibrosing Alopecia and Increased Scalp Sweating: Is Neurogenic Inflammation the Common Link?

Frontal fibrosing alopecia (FFA) is an uncommon scarring hair loss disorder that is characterized by a band-like recession of the frontal hair line with eyebrow hair loss. We present a series of patients with FFA and increased sweating predominantly localized to the scalp, and potential explanations for this association are discussed. We hypothesize that the reported increase in sweating seen in our patients may be in part related to the inflammatory process occurring locally within the skin, either inducing a local axonal sweating reflex or through direct modulation of sweat gland secretion by neuropeptides.

The Success of Thread-embedding Therapy in Generating Hair Re-growth in Mice Points to Its Possibly Having a Similar Effect in Humans

Objectives:

Recently, thread-embedding therapy (TET) has been widely applied in Korean medicine for cosmetic purposes such as reducing skin wrinkles. An inserted thread was reported to have induced continuous stimulation, followed by support for connective tissue regeneration. However, the potential role of TET in hairgrowth has not yet been reported.

Methods:

We designed this study to evaluate whether TET has a hair-growth-promoting effect. C57 black 6 (C57BL/6) mice were divided into three groups: normal saline-treated, minoxidil-treated, and thread-embedded groups. Normal saline or 5% minoxidil was topically sprayed on the dorsal skin of the mice once a day for 16 days. Medical threads were embedded into the dorsal skin of the mice in a single application. Hair growth activity was evaluated by using dermoscopic and microscopic observations. Sections of the dorsal skin were stained with hematoxylin and eosin. Expressions of bromodeoxyuridine (BrdU), proliferating cell nuclear antigen (PCNA), fibroblast growth factor-7 (FGF-7), and fibroblast growth factor-5 (FGF-5) were detected by using immunohistochemical staining. A reverse transcription-polymerase chain reaction (RT-PCR) analysis was adopted to measure the messenger RNA (mRNA) expressions of FGF-7 and FGF-5.

Results:

TET enhanced anagen development in the hair follicles of C57BL/6 mice. The expressions of BrdU and PCNA, both of which imply active cellular proliferation, were increased by using TET. Moreover, TET increased the expression of FGF-7, an anagen-inducing growth factor, while decreasing the expression of FGF-5, an anagen-cessation growth factor, both at the protein and the mRNA levels.

Conclusion:

TET enhanced hair re-growth in C57BL/6 mice. TET regulated the expressions of anagen-associated growth factors and activated the proliferation of hair follicular cells in depilated skin lesions. Considering its long-lasting effect, TET may be a good alternative therapeutic for the treatment of alopecia.

Cicatricial alopecia: What’s new in etiology?

Cicatricial alopecia is a rare, clinically diversified set of disorders causing permanent and irreversible hair loss, which often results in serious discomfort and patient’s mental problems.

Clinically, this form of irreversible hair loss is characterized by visible loss of hair follicle openings in the bald spots. Histologically, it consists in destroying a hair follicle and replacing it with fibrocartilage. Such disorders are perceived as primary if a hair follicle itself is the target of the disease process and secondary if hair follicles are damaged incidentally in the context of more general tissue damage (e.g. deep skin infections, thermal burns, trauma or ionizing radiation).

In this article we tried to summarize the knowledge on possible pathogenic mechanisms of cicatricial alopecia. The presented factors usually overlap and affect prognosis of particular patients. Their profound understanding may enable further research on the treatment methods of this challenging disease unit.