Indications for a 'brain-hair follicle axis (BHA)': inhibition of keratinocyte proliferation and up-regulation of keratinocyte apoptosis in telogen hair follicles by stress and substance P

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.

Cutaneous neuropeptides: the missing link between psychological stress and chronic inflammatory skin disease?

A "brain-skin" connection has been long been observed between chronic stress and chronic inflammatory skin disease including urticaria, psoriasis, atopic dermatitis, and prurigo nodularis. The relationship appears to be bidirectional. Chronic psychological stress has been shown to sustain hyperactivity of the sympathetic branch of the autonomic nervous system. Chronic stress is proinflammatory and in the context of several dermatologic disorders may be associated with an increase in dermal nerve fiber density, mast cells, nerve growth factor and calcitonin-gene-related peptide (CGRP). Furthermore, CGRP elicits a TH2-polarized T-cell response that is a hallmark of chronic pruritic conditions such as atopic dermatitis and prurigo nodularis. This TH2 response contributes directly to acute pruritus as well as the sensitization of cutaneous sensory neurons that are critical for chronic pruritus. Prurigo nodularis is a debilitating skin disorder featuring prominent nerve structural, neuropeptide, and TH2 cytokine aberrations that is a model deserving of future study.

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.

Frontiers in Lichen Planopilaris and Frontal Fibrosing Alopecia Research: Pathobiology Progress and Translational Horizons

Lichen planopilaris (LPP) and frontal fibrosing alopecia (FFA) are primary, lymphocytic cicatricial hair loss disorders. These model epithelial stem cell (SC) diseases are thought to result from a CD8⁺ T-cell‒dominated immune attack on the hair follicle (HF) SC niche (bulge) after the latter has lost its immune privilege (IP) for as yet unknown reasons. This induces both apoptosis and pathological epithelial‒mesenchymal transition in epithelial SCs, thus depletes the bulge, causes fibrosis, and ultimately abrogates the HFs' capacity to regenerate. In this paper, we synthesize recent progress in LPP and FFA pathobiology research, integrate our limited current understanding of the roles that genetic, hormonal, environmental, and other factors may play, and define major open questions. We propose that LPP and FFA share a common initial pathobiology, which then bifurcates into two distinct clinical phenotypes, with macrophages possibly playing a key role in phenotype determination. As particularly promising translational research avenues toward direly needed progress in the management of these disfiguring, deeply distressful cicatricial alopecia variants, we advocate to focus on the development of bulge IP and epithelial SC protectants such as, for example, topically effective, HF‒penetrating and immunoinhibitory preparations that contain tacrolimus, peroxisome proliferator-activated receptor-γ, and/or CB1 agonists.

Advancing Regenerative Cellular Therapies in Non-Scarring Alopecia

Alopecia or baldness is a common diagnosis in clinical practice. Alopecia can be scarring or non-scarring, diffuse or patchy. The most prevalent type of alopecia is non-scarring alopecia, with the majority of cases being androgenetic alopecia (AGA) or alopecia areata (AA). AGA is traditionally treated with minoxidil and finasteride, while AA is treated with immune modulators; however, both treatments have significant downsides. These drawbacks compel us to explore regenerative therapies that are relatively devoid of adverse effects. A thorough literature review was conducted to explore the existing proven and experimental regenerative treatment modalities in non-scarring alopecia. Multiple treatment options compelled us to classify them into growth factor-rich and stem cell-rich. The growth factor-rich group included platelet-rich plasma, stem cell-conditioned medium, exosomes and placental extract whereas adult stem cells (adipose-derived stem cell-nano fat and stromal vascular fraction; bone marrow stem cell and hair follicle stem cells) and perinatal stem cells (umbilical cord blood-derived mesenchymal stem cells (hUCB-MSCs), Wharton jelly-derived MSCs (WJ-MSCs), amniotic fluid-derived MSCs (AF-MSCs), and placental MSCs) were grouped into the stem cell-rich group. Because of its regenerative and proliferative capabilities, MSC lies at the heart of regenerative cellular treatment for hair restoration. A literature review revealed that both adult and perinatal MSCs are successful as a mesotherapy for hair regrowth. However, there is a lack of standardization in terms of preparation, dose, and route of administration. To better understand the source and mode of action of regenerative cellular therapies in hair restoration, we have proposed the "À La Mode Classification". In addition, available evidence-based cellular treatments for hair regrowth have been thoroughly described.

The redox modulatory effects of SP/NK1R system: Implications for oxidative stress-associated disorders

Oxidative stress which refers to redox imbalance with increased generation of reactive oxygen species (ROS) has been associated with the pathophysiology of diverse disease conditions. Recently, a close, yet not fully understood, relation between oxidative stress and neuropeptides, in particular, substance P (SP), has been reported in certain conditions. SP has been shown to affect the cellular redox environment through activation of neurokinin-1receptor (NK1R). It seems that SP/NK1R system and oxidative stress can act either synergistically or antagonistically in a context-dependent manner, thereby, influencing the pathology of various clinical disorders either destructively or protectively. Importantly, the interactions between oxidative stress and SP/NK1R system can be pharmacologically targeted. Therefore, a better understanding of the redox modulatory properties of SP/NK1R signaling will pave the way for identifying new therapeutic possibilities for attenuating oxidative stress-mediated damage. Towards this end, we performed a comprehensive search through PubMed/Medline and Scopus databases and discussed all related existing literature regarding the interplay between oxidative stress and SP/NK1R system as well as their implication in various clinical disorders, to provide a clear view and hence better management of oxidative damage.

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 presence of mast cells in lichen planopilaris and discoid lupus erythematosus of the scalp; a quantitative study

BACKGROUND

Histopathologic differentiation of Lichen planopilaris (LPP) and discoid lupus erythematosus (DLE) as the two common causes of primary cicatricial alopecias remains challenging.

METHOD

We performed a histopathologic study on a case series of LPP and DLE specimens to investigate the number, distribution, and morphology of mast cells as indices for differentiation of these two entities. H & E investigation and Giemsa staining for the detection of mast cells was performed.

RESULT

A total of 74 cases comprising 50 cases of LPP and 24 cases of DLE, were assessed. The mean mast cell count and percentage were significantly higher in LPP group (P <0.001). Mean degranulated mast cell count and the mean intact mast cell count were also significantly higher in LPP patients (P <0.001). Most of the specimens, 58 (78.4%), showed both perifollicular and perivascular distribution of mast cells without significant diffrence between two groups. The morphology of mast cells was predominantly round-oval in 85.5%, predominantly fusiform in 13.5% with more frequent fusiform morphology in DLE group.

CONCLUSION

The mast cell count detected by Giemsa staining could assist pathologists in distinguishing between LPP and DLE. This article is protected by copyright. All rights reserved.

Intravenous dexmedetomidine, morphine, or a combination can result in gallbladder wall thickening; with no significant association with plasma histamine concentrations

The gallbladder is routinely evaluated during ultrasonographic examinations in dogs. However, published studies describing the effects of sedative agents on gallbladder wall thickness are currently lacking. The aims of this prospective, blinded, randomized crossover pilot study were to test hypotheses that IV morphine would result in gallbladder wall thickening, that morphine administration would increase plasma histamine concentrations, and that combining IV morphine with dexmedetomidine would potentiate gallbladder wall thickening. Six healthy Beagle dogs were sedated with intravenous (IV) morphine 0.4 mg/kg (group M), dexmedetomidine 7 μg/kg (group D), or a combination of the two (group MD). Physiologic parameters were measured at baseline and at regular intervals until the last ultrasonographic scan. Ultrasonographic scans were performed at baseline, 90 s, and at 5, 15, 30, 45, 60, 90, and 120 min. Plasma histamine samples were taken at baseline, 90 s, and 5 and 60 min. Cochran's Q-test was used to compare gallbladder wall thickening between groups, while the association between histamine plasma concentration and gallbladder wall thickness was compared with a mixed-effects model. Baseline gallbladder wall thickness was not significantly different between groups. Six of 18 treatments/dogs (33%) developed gallbladder thickening, with no difference between groups. There was no significant difference in baseline plasma histamine concentrations between groups, and no association between plasma histamine concentration and gallbladder wall thickness. Gallbladder wall thickening was observed in at least one dog in each group, therefore caution is recommended for gallbladder wall thickness ultrasonographic interpretation in dogs when these drugs have been administered.

Role of Substance P in Regulating Micro-Milieu of Inflammation in Alopecia Areata

Background

Alopecia areata (AA) is an autoimmune disease characterized by chronic inflammation, the pathogenesis of which is unknown. Stress is believed to play a role; however, evidence remains insufficient. A recent study showed that substance P (SP) damaged hair follicles by causing neurogenic inflammation, activating perifollicular mast cells, and inducing keratinocyte apoptosis.

Objective

We aimed at studying the role of SP in AA pathogenesis. We investigated the SP levels in the lesional scalp tissues and serum. We also studied the effect of SP on the inflammatory response and hair growth in the outer root sheath (ORS) cells.

Methods

We compared the serum levels of SP in 58 AA patients and 28 healthy subjects. Then, we checked the expression of SP and SP receptor, neurokinin-1 receptor (NK-1R) in the scalps of AA patients and healthy controls using immunohistochemical staining. Finally, we analyzed the mRNA expression of inflammatory cytokines and hair growth-related factors in ORS cells.

Results

SP and NK-1R expression were markedly higher in the hair follicles and interfollicular epidermis of the scalp lesions of AA patients. However, there was no statistically significant difference in serum SP levels between controls and patients, regardless of the type of alopecia. SP significantly increased the mRNA expression of inflammatory cytokines and decreased hair growth-related growth factors in ORS cells, but the results were not dramatic.

Conclusion

SP triggered a localized micro-inflammation in lesional hair follicles, provoked an inflammatory response, and inhibited hair growth, thereby confirming the pathogenic role of SP in AA.

Trichodynia Revisited

Trichodynia refers to the painful sensation of the scalp related to the complaint of hair loss. Originally suggested to be distinguishing for telogen effluvium and related to hair loss activity and follicular inflammation, further studies have found trichodynia to be common in androgenetic alopecia as well and coexisting with psychopathologic findings. The respective studies failed to demonstrate correlations between trichodynia and quantifiable hair loss activity, nor histopathologic evidence for follicular inflammation. A symptomatic scalp is a frequent condition in specific dermatological conditions of the scalp. By definition of exclusion, we are not dealing with trichodynia in these cases. It is conceivable that neuropeptides are key players between the central nervous system and the skin immune and microvascular system. Such mechanisms would explain the noxious effects of both external stimuli and emotional distress in eliciting cutaneous nociception. Since we have begun to understand the diverse etiologies of trichodynia, and a single term does not measure up to this circumstance, it may be wiser to describe the condition depending on the type of scalp sensation and its specific disease association. Further studies are warranted into the neural/endothelial/follicular interactions both in hair growth and shedding and the psychosomatic diseases of the hair and scalp.

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.

Effects of environmental enrichment on growth performance, carcass traits, meat quality, and hair follicle development of Rex rabbits

OBJECTIVE

The purpose of this study was to investigate growth performance, carcass traits, meat quality and hair follicle development of growing Rex rabbits as affected by different environmental enrichment materials.

METHODS

A total of one hundred and twenty Rex rabbits were randomly assigned to four groups; reared in conventional cages (not enriched) and in enriched cages with either willow stick (WS), rubber duck, or a can containing beans (CB), for 44 days.

RESULTS

The average daily gain of the CB group was the highest and had a significant difference from that of the other groups (p<0.05). The spleen and cecum weight of the CB group was greater than those of the WS and control groups (p<0.05). The redness (Commission Internationale de l'Eclairage a*) of the meat sample of the control group was lower than those of the enriched cage groups (p<0.05). Moreover, the hue value of the CB group was significantly lower than that of the other groups (p<0.05). The tenderest meat belonged to the CB group. In addition, more secondary (p<0.05) and primary follicles were found in the CB group than in the control group.

CONCLUSION

Environmental enrichment increased the average daily gain and improved some carcass traits, meat quality, and hair follicle density. Among the three environmental enrichment materials, CB could be recommended for rabbit husbandry.

Immune cell regulation of the hair cycle

The ability to manipulate the mammalian hair cycle will lead to novel therapies and strategies to combat all forms of alopecia. Thus, in addition to the epithelial-mesenchymal interactions in the hair follicle, niche and microenvironmental signals that accompany the phases of growth, regression and rest need to be scrutinized. Immune cells are well described in skin homeostasis and wound healing and have recently been shown to play an important role in the mammalian hair cycle. In this review, we will summarize our current knowledge of the role of immune cells in hair cycle control and discuss their relevance to human hair cycling disorders. Increased attention to this aspect of the hair cycle will provide new avenues to manipulate hair regeneration in humans and provide better insight into developing better ex vivo models of hair growth.

Tissue-resident macrophages can be generated de novo in adult human skin from resident progenitor cells during substance P-mediated neurogenic inflammation ex vivo

Besides monocyte (MO)-derived macrophages (MACs), self-renewing tissue-resident macrophages (trMACs) maintain the intracutaneous MAC pool in murine skin. Here, we have asked whether the same phenomenon occurs in human skin using organ-cultured, full-thickness skin detached from blood circulation and bone marrow. Skin stimulation ex vivo with the neuropeptide substance P (SP), mimicking neurogenic skin inflammation, significantly increased the number of CD68⁺MACs in the papillary dermis without altering intracutaneous MAC proliferation or apoptosis. Since intraluminal CD14⁺MOs were undetectable in the non-perfused dermal vasculature, new MACs must have differentiated from resident intracutaneous progenitor cells in human skin. Interestingly, CD68⁺MACs were often seen in direct cell-cell-contact with cells expressing both, the hematopoietic stem cell marker CD34 and SP receptor (neurokinin-1 receptor [NK1R]). These cell-cell contacts and CD34⁺cell proliferation were up-regulated in SP-treated skin samples. Collectively, our study provides the first evidence that resident MAC progenitors, from which mature MACs can rapidly differentiate within the tissue, do exist in normal adult human skin. That these NK1R⁺trMAC-progenitor cells quickly respond to a key stress-associated neuroinflammatory stimulus suggests that this may satisfy increased local MAC demand under conditions of wounding/stress.

Protective effects of human umbilical cord blood‑derived mesenchymal stem cells against dexamethasone‑induced apoptotic cell death in hair follicles

Alopecia is a common and distressing condition, and developing new therapeutic agents to prevent hair loss is important. Human umbilical cord blood‑derived mesenchymal stem cells (hUCB‑MSCs) have been studied intensively in regenerative medicine. However, the therapeutic potential of these cells against hair loss and hair organ damage remains unclear, and the effects of hUCB‑MSC transplantation on hair loss require evaluation. The current study aimed to investigate the effects of hUCB‑MSCs on hair regression in vivo and restoration of anagen conduction on hair growth in vitro. The effects of hUCB‑MSCs were explored in mouse catagen induction models using a topical treatment of 0.1% dexamethasone to induce hair regression. Dexamethasone was also used to simulate a stress environment in vitro. The results demonstrated that hUCB‑MSCs significantly prevented hair regression induced by dexamethasone topical stimulation in vivo. Additionally, hUCB‑MSCs significantly increased the proliferation of human dermal papilla cells (hDPCs) and HaCaT cells, which are key constituent cells of the hair follicle. Stimulation of vascular endothelial growth factor secretion and decreased expression of DKK‑1 by hUCB‑MSCs were also observed in hDPCs. Restoration of cell viability by hUCB‑MSCs suggested that these cells exerted a protective effect on glucocorticoid stress‑associated hair loss. In addition, anti‑apoptotic effects and regulation of the autophagic flux recovery were observed in HaCaT cells. The results of the present study indicated that hUCB‑MSCs may have the capacity to protect hair follicular dermal papilla cells and keratinocytes, thus preventing hair loss. Additionally, the protective effects of hUCB‑MSCs may be resistant to dysregulation of autophagy under harmful stress.

Alopecia areata is characterized by dysregulation in systemic type 17 and type 2 cytokines, which may contribute to disease-associated psychological morbidity

BACKGROUND

Alopecia areata (AA) is a common autoimmune disease, causing patchy hair loss that can progress to involve the entire scalp (totalis) or body (universalis). CD8⁺ NKG2D⁺ T cells dominate hair follicle pathogenesis, but the specific mechanisms driving hair loss are not fully understood.

OBJECTIVES

To provide a detailed insight into the systemic cytokine signature associated with AA, and to assess the association between cytokines and depression.

METHODS

We conducted multiplex analysis of plasma cytokines from patients with AA, patients with psoriatic arthritis (PsA) and healthy controls. We used the Hospital Anxiety and Depression Scale (HADS) to assess the occurrence of depression and anxiety in our cohort.

RESULTS

Our analysis identified a systemic inflammatory signature associated with AA, characterized by elevated levels of interleukin (IL)-17A, IL-17F, IL-21 and IL-23 indicative of a type 17 immune response. Circulating levels of the type 2 cytokines IL-33, IL-31 and IL-17E (IL-25) were also significantly increased in AA. In comparison with PsA, AA was associated with higher levels of IL-17F, IL-17E and IL-23. We hypothesized that circulating inflammatory cytokines may contribute to wider comorbidities associated with AA. Our assessment of psychiatric comorbidity in AA using HADS scores showed that 18% and 51% of people with AA experienced symptoms of depression and anxiety, respectively. Using linear regression modelling, we identified that levels of IL-22 and IL-17E are positively and significantly associated with depression.

CONCLUSIONS

Our data highlight changes in both type 17 and type 2 cytokines among people with AA, suggesting that complex systemic cytokine profiles may contribute both to the pathogenesis of AA and to the associated depression. What's already known about this topic? NKG2D⁺ CD8⁺ T cells cause hair loss in alopecia areata (AA) but the immunological mechanisms underlying the disease are not fully understood. AA is associated with changes in levels of interleukin (IL)-6, tumour necrosis factor-α, IL-1β and type 17 cytokines. Psychiatric comorbidity is common among people with AA. What does this study add? People with AA have increased plasma levels of the type 2 cytokines IL-33, IL-31 and IL-17E (IL-25), in addition to the type 17 cytokines IL-17A, IL-21, IL-23 and IL-17F. Levels of IL-17E and IL-22 positively predict depression score. What is the translational message? AA is associated with increased levels of multiple inflammatory cytokines, implicating both type 17- and type 2 immune pathways. Our data indicate that therapeutic strategies for treating AA may need to address the underlying type 17- and type 2 immune dysregulation, rather than focusing narrowly on the CD8⁺ T-cell response. An immunological mechanism might contribute directly to the depression observed in people with AA.

Relationship between working hours and probability to take alopecia medicine among Korean male workers: a 4-year follow-up study

Background

Many studies have reported the negative effects of long working hours on various health problems. However, whether hair loss is associated with working hours has been rarely investigated so far. The main purpose of this study is to explore the relationship between long working hours and the development of alopecia among Korean male workers.

Methods

A total of 13,391 male workers not to take alopecia medicine in 2013 were followed up to see if they have alopecia medicine after 4 years, and that was used to confirm the alopecia development. Weekly working hours were categorized into three groups: reference working hours (RWH; < 40 hours/week), long working hours (LWH, 40–52 hours/week), and much longer working hours (MLWH; > 52 hours/week). Multiple logistic regression analyses were conducted to investigate the relationship between long working hours and the development of alopecia after adjusting age, marital status, education, monthly household income, smoking, and work schedule within strata of the covariates.

Results

Long working hours was significantly related to the development of alopecia. The adjusted odds ratios (ORs) for the development of alopecia were 1.57 (95% confidence interval [CI]: 1.21–2.05) for LWH group and 1.74 (95% CI: 1.23–2.47) for MLWH group relative to RWH group.

Conclusions

Our findings suggest that unintentional development of alopecia is another potential health consequence of long working hours among Korean male workers. Preventive interventions to promote appropriate and reasonable working hours are required in our society.

Alopecia areata: a review of disease pathogenesis

BACKGROUND

Alopecia areata is a disorder that results in nonscarring hair loss. The psychological impact can be significant, leading to feelings of depression and social isolation. Objectives In this article, we seek to review the pathophysiological mechanisms proposed in recent years in a narrative fashion.

METHODS

We searched MEDLINE and Scopus for articles related to alopecia areata, with a particular emphasis on its pathogenesis.

RESULTS

The main theory of alopecia areata pathogenesis is that it is an autoimmune phenomenon resulting from a disruption in hair follicle immune privilege. What causes this breakdown is an issue of debate. Some believe that a stressed hair follicle environment triggers antigen presentation, while others blame a dysregulation in the central immune system entangling the follicles. Evidence for the latter theory is provided by animal studies, as well investigations around the AIRE gene. Different immune-cell lines including plasmacytoid dendritic cells, natural killer cells and T cells, along with key molecules such as interferon-γ, interleukin-15, MICA and NKG2D, have been identified as contributing to the autoimmune process.

CONCLUSIONS

Alopecia areata remains incurable, although it has been studied for years. Available treatment options at best are beneficial for milder cases, and the rate of relapse is high. Understanding the exact mechanisms of hair loss in alopecia areata is therefore of utmost importance to help identify potential therapeutic targets.

Immune Privilege Collapse and Alopecia Development: Is Stress a Factor

Hair is a defining mammalian feature that serves as a hallmark of human communication. Given the critical significance of hair in social, religious, and political contexts, it is important to understand factors that play a role in hair loss disorders. The hair follicle is an immune privileged site, and mounting evidence suggests that the collapse of immune privilege contributes to the pathogenesis of autoimmune hair loss disorders, including alopecia areata and lichen planopilaris. This review comprehensively appraises the current literature to shed light on mechanisms for immune privilege collapse, and examines the role of neurogenic stress in triggering this process.

NK1R/5-HT1AR interaction is related to the regulation of melanogenesis

Substance P (SP) is a candidate mediator along the brain-skin axis and can mimic the effects of stress to regulate melanogenesis. Previously, we and others have found that the regulation of SP for pigmentary function was mediated by neurokinin 1 receptor (NK1R). Emerging evidence has accumulated that psychologic stress can induce dysfunction in the cutaneous serotonin 5-hydroxytryptamine (5-HT)-5-HT1A/1B receptor system, thereby resulting in skin hypopigmentation. Moreover, NK1R and 5-HTR (except 5-HT3) belong to GPCR. The present study aimed at assessing the possible existence of NK1R-5-HTR interactions and related melanogenic functions. Western blot and PCR detection revealed that SP reduced expression of 5-HT1A receptor via the NK1 receptor. Biochemical analyses showed that NK1R and 5-HT1AR could colocalize and interact in a cell and in the skin. When the N terminus of the NK1R protein was removed NK1R surface targeting was prevented, the interaction between NK1R-5-HT1AR decreased, and the depigmentation caused by SP and WAY100635 could be rescued. Importantly, pharmaceutical coadministration of NK1R agonist (SP) and 5-HT1A antagonist (WAY100635) enhanced the NK1-5-HT1A receptor coimmunoprecipitation along with the depigmentary response. SP and WAY100635 cooperation elicited activation of a signaling cascade (the extracellular, regulated protein kinase p-JNK signaling pathway) and inhibition of p70S6K1 phosphorylation and greatly reduced melanin production in vitro and in vivo in mice and zebrafish. Moreover, the SP-induced depigmentation response did not be occur in 5-htr1aa^+/- zebrafish embryos. Taken together, the results of our systemic study increases our knowledge of the roles of NK1R and 5-HT1AR in melanogenesis and provides possible, novel therapeutic strategies for treatment of skin hypo/hyperpigmentation.-Wu, H., Zhao, Y., Huang, Q., Cai, M., Pan, Q., Fu, M., An, X., Xia, Z., Liu, M., Jin, Y., He, L., Shang, J. NK1R/5-HT1AR interaction is related to the regulation of melanogenesis.

Effect of Miscanthus sinensis var. purpurascens Flower Extract on Proliferation and Molecular Regulation in Human Dermal Papilla Cells and Stressed C57BL/6 Mice

OBJECTIVES

To investigate the hair growth-promoting effect of Miscanthus sinensis var. purpurascens (MSP) flower extracton on in vitro and in vivo models.

METHODS

MSP flower extract was extracted in 99.9% methanol and applied to examine the proliferation of human dermal papilla cells (hDPCs) in vitro at the dose of 3.92-62.50 μg/mL and hair growth of C57BL/6 mice in vivo at the dose of 1000 μg/mL. The expression of transforming growth factor β1 (TGF-β1), hepatocyte growth factor (HGF), β-catenin, substance P was measured by relative quantitative realtime polymerase chain reaction. Histopathological and immunohistochemical analysis were performed.

RESULTS

MSP (7.81 μg/mL) down-regulated TGF-β1 and up-regulated HGF and β-catenin in hDPCs (P<0.01). MSP (1000 μg/mL)-treated mice showed the earlier transition of hair follicles from the telogen to the anagen phase. The number of mast cells was lower in the MSP-treated mice than in other groups (P<0.05 vs. NCS group). Substance P and TGF-β1 were expressed in hair follicles and skin of the MSP group lower than that in negative control. Stem cell factor in hair follicles was up-regulated in the MSP-treated mice (P<0.01).

CONCLUSIONS

The MSP flower extract may have hair growth-promotion activities.

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.

Cross-talk between 5-hydroxytryptamine and substance P in the melanogensis and apoptosis of B16F10 melanoma cells

Skin pigmentation is a complex process controlled by many different factors. Substance P (SP) regulates many biological functions, including melanogenesis and stress. Our previous study indicated that regulation of SP on melanocyte function was mediated by neurokinin 1 receptor (NK1 receptor). Substantial evidence has accumulated that psychological stress can be associated with skin pigmentation, so that the impact of 5-hydroxytryptamine (5-HT), one of the important factors participating in stress process, on melanogenesis has also been concerned. It has been reported that 5-HT induces melanin synthesis via 5-HT2A receptor. Furthermore, 5-HT2A receptor and NK1 receptor are G-protein coupled receptors (GPCRs) and both expressed on melanocyte, the present study was designed to investigate whether SP has influence on the adjustment function of 5-HT. Our data demonstrated that, SP inhibited 5-HT2A receptor expression to neutralize the pro-melanogenesis effect of 5-HT on B16F10 cells. The up-regulation of NK1 receptor expression was simultaneous with the down-regulation of 5-HT2A receptor treated by SP. This inhibition of 5-HT2A receptor expression by SP could be reversed by NK1 receptor antagonist Spantide I. Our studies indicated that SP could directly induce B16F10 cells apoptosis in vitro. 5-HT and 5-HT2A receptor agonist could mitigate this apoptotic effect of SP. It is the strong evidence of possible cross-talk between GPCRs and giving enlightenments when screening desirable drugs for target receptors.

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.

Resting no more: re-defining telogen, the maintenance stage of the hair growth cycle

The hair follicle (HF) represents a prototypic ectodermal-mesodermal interaction system in which central questions of modern biology can be studied. A unique feature of these stem-cell-rich mini-organs is that they undergo life-long, cyclic transformations between stages of active regeneration (anagen), apoptotic involution (catagen), and relative proliferative quiescence (telogen). Due to the low proliferation rate and small size of the HF during telogen, this stage was conventionally thought of as a stage of dormancy. However, multiple lines of newly emerging evidence show that HFs during telogen are anything but dormant. Here, we emphasize that telogen is a highly energy-efficient default state of the mammalian coat, whose function centres around maintenance of the hair fibre and prompt responses to its loss. While actively retaining hair fibres with minimal energy expenditure, telogen HFs can launch a new regeneration cycle in response to a variety of stimuli originating in their autonomous micro-environment (including its stem cell niche) as well as in their external tissue macro-environment. Regenerative responses of telogen HFs change as a function of time and can be divided into two sub-stages: early 'refractory' and late 'competent' telogen. These changing activities are reflected in hundreds of dynamically regulated genes in telogen skin, possibly aimed at establishing a fast response-signalling environment to trauma and other disturbances of skin homeostasis. Furthermore, telogen is an interpreter of circadian output in the timing of anagen initiation and the key stage during which the subsequent organ regeneration (anagen) is actively prepared by suppressing molecular brakes on hair growth while activating pro-regenerative signals. Thus, telogen may serve as an excellent model system for dissecting signalling and cellular interactions that precede the active 'regenerative mode' of tissue remodeling. This revised understanding of telogen biology also points to intriguing new therapeutic avenues in the management of common human hair growth disorders.

Brain-skin connection: stress, inflammation and skin aging

The intricate relationship between stress and skin conditions has been documented since ancient times. Recent clinical observations also link psychological stress to the onset or aggravation of multiple skin diseases. However, the exact underlying mechanisms have only been studied and partially revealed in the past 20 years or so. In this review, the authors will discuss the recent discoveries in the field of “Brain-Skin Connection”, summarizing findings from the overlapping fields of psychology, endocrinology, skin neurobiology, skin inflammation, immunology, and pharmacology.

Successful treatment of multiplex alopecia areata using transactional analysis: a case report

The patient was a 13-year-old female. Six years previously, she developed alopecia areata when her parents divorced. One year after that, the bald area drastically expanded when her mother remarried. She was treated at her local hospital; however, no improvement was observed. She then visited our hospital for examination. A bald patch was covering >80% of her head. Self Grow-Up Egogram indicated the basic interpersonal relationship stance of ‘I am not OK, You are OK’. We therefore implemented a transactional analysis approach to increase the patient's score on the Free Child subscale. New hair growth was observed after 6 months and the bald patch disappeared after 2 years. Our results suggest that this method could also be easily applied in a clinical setting by dermatologists.

Restraint stress alters immune parameters and induces oxidative stress in the mouse uterus during embryo implantation

The influence of stress on embryo implantation is not well understood. Prior studies have focused on later gestational stages and the long-term impact of stress on immune function. The objective of this study is to investigate the effects of restraint stress on the immune parameters and the oxidative states of the uterus during implantation. In this study, pregnant CD1 mice were subjected to restraint stress (4 h/d) on embryonic day 1 (E1) and sacrificed on E3, E5, and E7. Maternal plasma corticosterone (CORT) secretion and implantation sites in the uterus were examined. The uterine (excluding embryos) homogenate and uterine lymphocytes were collected to examine oxidative stress states and associated immune parameters. The results demonstrated that restraint stress increased maternal plasma CORT secretion and reduced the number of implantation sites by 15.3% on E5 and by 26.1% on E7. Moreover, restraint stress decreased the density of uterine natural killer (uNK) cells in the endometrium by 22.1-47.9% and increased the density of mast cells in the myometrium by 55.6-76.9%. Restraint stress remarkably decreased the CD3(+)CD4(+) T/CD3(+)CD8(+) T cell ratio (by 26.2-28.9%) and attenuated uterine lymphocyte proliferation and secretion of cytokines. In addition, restraint stress threatened the intracellular equilibrium between oxidants and antioxidants, resulting in decreased glutathione peroxidase (GSH-PX) (32.2% and 45.7%), superoxide dismutase (SOD) (15.5% and 26.1%), and total antioxidant capacity (T-AOC) (18.4% and 18.2%) activities and increased malondialdehyde (MDA) (34.4% and 43.0%) contents on E5 and E7. In conclusion, these findings demonstrate that restraint stress causes abnormal implantation and negatively impacts immune parameters in association with oxidative stress in mice.

Stress-induced mast cell activation in glabrous and hairy skin

Mast cells play a key role in modulation of stress-induced cutaneous inflammation. In this study we investigate the impact of repeated exposure to stress on mast cell degranulation, in both hairy and glabrous skin. Adult male Wistar rats were randomly divided into four groups: Stress 1 day (n = 8), Stress 10 days (n = 7), Stress 21 days (n = 6), and Control (n = 8). Rats in the stress groups were subjected to 2 h/day restraint stress. Subsequently, glabrous and hairy skin samples from animals of all groups were collected to assess mast cell degranulation by histochemistry and transmission electron microscopy. The impact of stress on mast cell degranulation was different depending on the type of skin and duration of stress exposure. Short-term stress exposure induced an amplification of mast cell degranulation in hairy skin that was maintained after prolonged exposure to stress. In glabrous skin, even though acute stress exposure had a profound stimulating effect on mast cell degranulation, it diminished progressively with long-term exposure to stress. The results of our study reinforce the view that mast cells are active players in modulating skin responses to stress and contribute to further understanding of pathophysiological mechanisms involved in stress-induced initiation or exacerbation of cutaneous inflammatory processes.

Hair curvature: a natural dialectic and review

Although hair forms (straight, curly, wavy, etc.) are present in apparently infinite variations, each fibre can be reduced to a finite sequence of tandem segments of just three types: straight, bent/curly, or twisted. Hair forms can thus be regarded as resulting from genetic pathways that induce, reverse or modulate these basic curvature modes. However, physical interconversions between twists and curls demonstrate that strict one-to-one correspondences between them and their genetic causes do not exist. Current hair-curvature theories do not distinguish between bending and twisting mechanisms. We here introduce a multiple papillary centres (MPC) model which is particularly suitable to explain twisting. The model combines previously known features of hair cross-sectional morphology with partially/completely separated dermal papillae within single follicles, and requires such papillae to induce differential growth rates of hair cortical material in their immediate neighbourhoods. The MPC model can further help to explain other, poorly understood, aspects of hair growth and morphology. Separate bending and twisting mechanisms would be preferentially affected at the major or minor ellipsoidal sides of fibres, respectively, and together they exhaust the possibilities for influencing hair-form phenotypes. As such they suggest dialectic for hair-curvature development. We define a natural-dialectic (ND) which could take advantage of speculative aspects of dialectic, but would verify its input data and results by experimental methods. We use this as a top-down approach to first define routes by which hair bending or twisting may be brought about and then review evidence in support of such routes. In particular we consider the wingless (Wnt) and mammalian target of rapamycin (mTOR) pathways as paradigm pathways for molecular hair bending and twisting mechanisms, respectively. In addition to the Wnt canonical pathway, the Wnt/Ca(2+) and planar cell polarity (PCP) pathways, and others, can explain many alternatives and specific variations of hair bending phenotypes. Mechanisms for hair papilla budding or its division by bisection or fission can explain MPC formation. Epithelial-to-mesenchymal (EMT) and mesenchymal-to-epithelial (MET) transitions, acting in collaboration with epithelial-mesenchymal communications are also considered as mechanisms affecting hair growth and its bending and twisting. These may be treated as sub-mechanisms of an overall development from neural-crest stem cell (NCSC) lineages to differentiated hair follicle (HF) cell types, thus providing a unified framework for hair growth and development.

Chronic psychological stress suppresses contact hypersensitivity: potential roles of dysregulated cell trafficking and decreased IFN-γ production

Increasing evidence shows that psychological stress can have dramatic impacts on the immune system, particularly the cutaneous immune response in dermatological disorders. While there have been many studies examining the impact of acute psychological stress on contact hypersensitivity there are relatively few studies concerning the impact of chronic psychological stress. Furthermore, the local immunological mechanisms by which chronic psychological stress impacts contact hypersensitivity still remain to be explored. Here we show that restraint-induced chronic psychological stress stimulates activation of the hypothalamus-pituitary-adrenal axis and delays weight gain in female BALB/c mice. We observed that chronic psychological stress reduces the cutaneous immune response as evidence by reduced ear swelling. This correlated with a significant decrease in the inflammatory cell infiltrate. On the other hand, chronic psychological stress does not influence T cell proliferation, activation, or sensitivity to corticosterone but does increase CD4(+) and CD8(+) T cell percentages in draining lymph nodes during a contact hypersensitivity reaction. Chronic psychological stress induces a decrease in overall circulating white blood cells, lymphocytes, and monocytes during a contact hypersensitivity reaction suggesting extravasation from the circulation. Finally, we found markedly reduced local IFN-γ production in chronically stressed animals. Based on these findings we propose that chronic psychological stress reduces contact hypersensitivity due to dysregulated cell trafficking and reduced production of IFN-γ.

Reduced serum brain-derived neurotrophic factor in patients with first onset vitiligo

PURPOSE

Vitiligo is an acquired pigmentary skin disease that can cause serious cosmetic problems. There have been numerous and well established studies that have demonstrated the comorbidity of various psychiatric disorders in patients with vitiligo. However, to our knowledge, there have been no studies investigating whether a psychiatric biomarker, such as brain-derived neurotrophic factor (BDNF), is associated with vitiligo.

PATIENTS AND METHODS

This study was conducted in Namık Kemal University Medical Faculty, Departments of Dermatology and Psychiatry between January 2013 and September 2014. After meeting inclusion and exclusion criteria, serum BDNF levels were assayed in 57 patients with first onset vitiligo and no known current or past psychiatric disorder and compared with BDNF levels in 58 age and sex matched healthy subjects.

RESULTS

The age and female/male ratios were similar between groups. The mean values of serum BDNF were 1.57±0.97 ng/dL and 2.37±1.73 ng/dL in the vitiligo group and in the healthy control group, respectively. The mean BDNF level was significantly higher in the healthy control group compared with the vitiligo group (t=2.76, P=0.007).

CONCLUSION

This is the first study to compare serum BDNF levels between patients with vitiligo and healthy subjects. The reduced level of serum BDNF in patients with vitiligo may be directly related to the etiology of vitiligo or associated with the high percentage of psychiatric disorders in that patient population. Further studies are needed to support our preliminary results.

Chronic restraint stress inhibits hair growth via substance P mediated by reactive oxygen species in mice

Backgrounds

Solid evidence has demonstrated that psychoemotional stress induced alteration of hair cycle through neuropeptide substance P (SP) mediated immune response, the role of reactive oxygen species (ROS) in brain-skin-axis regulation system remains unknown.

Objectives

The present study aims to investigate possible mechanisms of ROS in regulation of SP-mast cell signal pathway in chronic restraint stress (CRS, a model of chronic psychoemotional stress) which induced abnormal of hair cycle.

Methods and Results

Our results have demonstrated that CRS actually altered hair cycle by inhibiting hair follicle growth in vivo, prolonging the telogen stage and delaying subsequent anagen and catagen stage. Up-regulation of SP protein expression in cutaneous peripheral nerve fibers and activation of mast cell were observed accompanied with increase of lipid peroxidation levels and reduction of the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) in CRS mice skin. In addition, SP receptor antagonist (RP67580) reduced mast cell activations and lipid peroxidation levels as well as increased GSH-Px activity and normalized hair cycle. Furthermore, antioxidant Tempol (a free radical scavenger) also restored hair cycle, reduced SP protein expression and mast cell activation.

Conclusions

Our study provides the first solid evidence for how ROS play a role in regulation of psychoemotional stress induced SP-Mast cell pathway which may provide a convincing rationale for antioxidant application in clinical treatment with psychological stress induced hair loss.

Inhibitory effect of tianeptine on catagen induction in alopecia areata-like lesions induced by ultrasonic wave stress in mice

BACKGROUND

Alopecia areata (AA) is characterized by rapid and complete hair loss in one or multiple areas of the scalp. Stress is an important triggering factor in AA.

AIM

To identify the inhibitory effect of tianeptine on catagen induction in C57BL/6 mice with AA-like lesions induced by ultrasonic wave stress (UWS).

METHODS

The mice were divided into four groups. Group 1 received oral tianeptine before and after UWS; group 2 received oral tianeptine only after UWS; group 3 was given UWS treatment only; and group 4 (negative control group) was not given any treatment. Phototrichigraphy and dermatoscopy were used for assessment. Histological analysis was performed using haematoxylin and eosin, toluidine blue, Masson trichrome and Verhoeff-van Gieson stains. Immunohistochemical analysis was also performed. The level of apoptosis and expression of neuropeptides in the skin were assessed by terminal deoxynucleotidyl transferase dUTP nick end labelling and immunofluorescence assays.

RESULTS

Mice in group 1 had an increased rate of hair growth and greater hair-shaft thickness compared with mice in groups 2 and 3. In addition, mice in group 1 had a higher number of anagen hair follicles, increased synthesis of collagen and elastic fibres, decreased mast-cell degranulation, reduction in cell apoptosis in hair follicles, and recovery of vitamin D receptor expression. Expression of neuropeptides (substance P, calcitonin gene-related peptide) was not altered.

CONCLUSIONS

Tianeptine might play a role in suppressing catagen induction in a stress-induced AA mouse model.

The basic science of hair biology: what are the causal mechanisms for the disordered hair follicle?

A hair disorder can be difficult to define, but patients are typically motivated to seek treatment when their hair growth patterns are significantly different from their cultural group or when growth patterns change significantly. The causes of hair disorders are many and varied, but fundamentally the disorder is a consequence of aberrant alterations of normal hair biology. The potential trigger factors for hair disorders can be attributed to inflammation, genetics, the environment, or hormones, of which the relative contributions vary for different diagnoses, between individuals, and over time. This article discusses the causal mechanisms for the disordered hair follicle.

Psychological Stress and the Cutaneous Immune Response: Roles of the HPA Axis and the Sympathetic Nervous System in Atopic Dermatitis and Psoriasis

Psychological stress, an evolutionary adaptation to the fight-or-flight response, triggers a number of physiological responses that can be deleterious under some circumstances. Stress signals activate the hypothalamus-pituitary-adrenal (HPA) axis and the sympathetic nervous system. Elements derived from those systems (e.g., cortisol, catecholamines and neuropeptides) can impact the immune system and possible disease states. Skin provides a first line of defense against many environmental insults. A number of investigations have indicated that the skin is especially sensitive to psychological stress, and experimental evidence shows that the cutaneous innate and adaptive immune systems are affected by stressors. For example, psychological stress has been shown to reduce recovery time of the stratum corneum barrier after its removal (innate immunity) and alters antigen presentation by epidermal Langerhans cells (adaptive immunity). Moreover, psychological stress may trigger or exacerbate immune mediated dermatological disorders. Understanding how the activity of the psyche-nervous -immune system axis impinges on skin diseases may facilitate coordinated treatment strategies between dermatologists and psychiatrists. Herein, we will review the roles of the HPA axis and the sympathetic nervous system on the cutaneous immune response. We will selectively highlight how the interplay between psychological stress and the immune system affects atopic dermatitis and psoriasis.

Psychiatric comorbidities in patients with alopecia areata in Taiwan: a case-control study

BACKGROUND

Alopecia areata (AA) may be related to stress and has been reported to be associated with psychiatric disorders. Nevertheless, a nationwide study of the relationship between AA and comorbid psychiatric diseases has not been conducted, and the effect of onset age has rarely been reported.

OBJECTIVES

To analyse the associations between AA and various psychiatric disorders using a nationwide database in Taiwan.

METHODS

Data were obtained from the National Health Insurance Research Database of Taiwan from 2000 to 2009. In total, 5117 patients with AA and 20 468 age- and gender-matched controls were enrolled.

RESULTS

Patients with AA tended to have more coexisting anxiety and less comorbid schizophrenia. Differences in ages of onset revealed differences in comorbidities. An increased risk of depression [odds ratio (OR) 2·23; 95% confidence interval (CI) 1·09-4·54] was found in patients with AA aged < 20years. An increased rate of anxiety (OR 1·43; CI 1·15-1·77) was observed with AA onset between the ages of 20 and 39years. The highest odds of obsessive-compulsive disorder (OR 3·00; CI 1·11-8·12) and anxiety (OR 2·05; CI 1·56-2·68) were observed in patients with AA aged 40-59years. Moreover, about 50% of psychiatric disorders occurred earlier than AA.

CONCLUSIONS

AA is related to various psychiatric disorders. Onset age of AA is an important factor in the association with different comorbid psychiatric diseases. In addition to cosmetic impact, which may bring about anxiety or depression, stress neuroendocrine immunology may play an important role in the pathogenesis of both AA and psychiatric disorders.

Central centrifugal cicatricial alopecia - an approach to diagnosis and management

Central centrifugal cicatricial alopecia (CCCA) occurs primarily in African-American women and is the most common cause of scarring hair loss in this population. Since the mid 20th century, hair care practices of African-American women have been associated with CCCA, although there is developing evidence that the etiology of CCCA may be multifactorial. Clinically diagnosing CCCA may be challenging because it can resemble female pattern hair loss, alopecia areata, lichen planopilaris, or telogen effluvium. Therapeutic options are limited, thus the goal of treatment is to prevent progression of disease because once scar formation occurs, it is irreversible.

Primary cicatricial alopecia: recent advances in understanding and management

Primary cicatricial alopecias (PCA) are a rare group of disorders, in which the hair follicle is the main target of destructive inflammation resulting in irreversible hair loss with scarring of affected lesions. The most typical clinical manifestation of PCA is the loss of visible follicular ostia. The histopathological hallmark of a fully developed lesion is the replacement of the hair follicle structure by fibrous tissue. PCA could share similar clinical manifestations and eventually lead to "burn-out" alopecia. Some subsets are hardly distinguishable histopathologically and the mechanisms that elicit such a destructive reaction have not been fully elucidated. Thus, the management of PCA represents one of the most challenging clinical problems for dermatologists. The aim of this review is to provide a concise and comprehensive summary of recent advances in PCA management, especially focusing on novel methodologies to aid diagnosis, and updates on our understanding of the etiopathogenesis. Dermoscopy, a new pathological preparation technique and direct immunofluorescence analysis enable more accurate clinicopathological diagnosis of PCA. Microarray analysis may be beneficial to distinguish PCA subtypes. Currently suggested mechanisms underlying PCA include loss of immune protection of stem cells, impaired stem cell self-maintenance, enhanced autoimmunity by pro-inflammatory cytokines and environmental/genetic predispositions. Interestingly, recent data indicates the association between lipid metabolism dysregulation and PCA development, implying an important role of the sebaceous gland dysfunction in the etiopathogenesis. Based on that hypothesis and observations, novel therapeutic approaches have been proposed, including the use of peroxisome proliferator-activated receptor-γ agonist for lichen planopilaris.

Pathophysiology of the Behçet's Disease

Behçet's disease (BD) is a multisystemic disease of unknown etiology characterized by chronic relapsing oral-genital ulcers and uveitis. Multiple systemic associations including articular, gastrointestinal, cardiopulmonary, neurologic, and vascular involvement are also observed in BD. Although the etiopathogenesis of the disease remains unknown, increased neutrophil functions such as chemotaxis, phagocytosis, and excessive production of reactive oxygen species (ROS), including superoxide anion, which may be responsible for oxidative tissue damage seen in BD, and also immunological alterations, T lymphocyte abnormalities in both subpopulation and function have been considered to be correlated with the etiopathogenesis of BD. There is some clinical evidence suggesting that emotional stress and hormonal alterations can influence the course and disease activity of BD.

The significant role of mast cells in cancer

Mast cells (MC) are a bone marrow-derived, long-lived, heterogeneous cellular population that function both as positive and negative regulators of immune responses. They are arguably the most productive chemical factory in the body and influence other cells through both soluble mediators and cell-to-cell interaction. MC are commonly seen in various tumors and have been attributed alternatively with tumor rejection or tumor promotion. Tumor-infiltrating MC are derived both from sentinel and recruited progenitor cells. MC can directly influence tumor cell proliferation and invasion but also help tumors indirectly by organizing its microenvironment and modulating immune responses to tumor cells. Best known for orchestrating inflammation and angiogenesis, the role of MC in shaping adaptive immune responses has become a focus of recent investigations. MC mobilize T cells and antigen-presenting dendritic cells. They function as intermediaries in regulatory T cells (Treg)-induced tolerance but can also modify or reverse Treg-suppressive properties. The central role of MC in the control of innate and adaptive immunity endows them with the ability to tune the nature of host responses to cancer and ultimately influence the outcome of disease and fate of the cancer patient.

The pathogenesis of primary cicatricial alopecias

Cicatricial (scarring) alopecia results from irreversible damage to epithelial stem cells located in the bulge region of the hair follicle, generally as a result of inflammatory mechanisms (eg, in the context of autoimmune disease). In primary cicactricial alopecia (PCA), the hair follicle itself is the key target of autoaggressive immunity. This group of permanent hair loss disorders can be classified into distinct subgroups, characterized by the predominant peri-follicular inflammatory cell type. In none of these PCA forms do we know exactly why hair follicles begin to attract such an infiltrate. Thus, it is not surprising that halting or even reversing this inflammation in PCA is often extremely difficult. However, increasing evidence suggests that healthy hair follicle epithelial stem cells enjoy relative protection from inflammatory assault by being located in an immunologically "privileged" niche. Because this protection may collapse in PCA, one key challenge in PCA research is to identify the specific signaling pathways that endanger, or restore, the relative immunoprotection of these stem cells. After a summary of pathobiological principles that underlie the development and clinical phenotype of PCA, we close by defining key open questions that need to be answered if more effective treatment modalities for this therapeutically very frustrating, but biologically fascinating, group of diseases are to be developed.