Norepinephrine Regulates Keratinocyte Proliferation to Promote the Growth of Hair Follicles

Tachykinins and the potential causal factors for post-COVID-19 condition

The most prevalent symptoms of post-COVID-19 condition are pulmonary dysfunction, fatigue and muscle weakness, anxiety, anosmia, dysgeusia, headaches, difficulty in concentrating, sexual dysfunction, and digestive disturbances. Hence, neurological dysfunction and autonomic impairments predominate in post-COVID-19 condition. Tachykinins including the most studied substance P are neuropeptides expressed throughout the nervous and immune systems, and contribute to many physiopathological processes in the nervous, immune, gastrointestinal, respiratory, urogenital, and dermal systems and participate in inflammation, nociception, and cell proliferation. Substance P is a key molecule in neuroimmune crosstalk; immune cells near the peripheral nerve endings can send signals to the brain with cytokines, which highlights the important role of tachykinins in neuroimmune communication. We reviewed the evidence that relates the symptoms of post-COVID-19 condition to the functions of tachykinins and propose a putative pathogenic mechanism. The antagonism of tachykinins receptors can be a potential treatment target.

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.

Recent Progress in the Understanding of the Effect of Sympathetic Nerves on Hair Follicle Growth

Clinical observation and experimental studies have long suggested that the perifollicular nerves have nutritional and regulatory effects on the growth, development, and physiological cycle of hair follicles (HFs), even though the concrete mechanism remains obscure. Recently, with the progress of immunohistochemistry and molecular biology techniques, more innovation has been made in the study of the follicular sympathetic nerves and its nerve-effect factor norepinephrine affecting hair follicle stem cells. This review highlights the progress in the regulation of the sympathetic nervous system toward the growth of HFs.

An increase in normetanephrine in hair follicles of acne lesions through the sympatho-adrenal medullary system in acne patients with anxiety

Acne vulgaris, a chronic inflammatory skin disease, has been associated with not only sebaceous gland dysfunction but also various endogenous and exogenous stresses. Since sebaceous glands are under neuroendocrine control, including the hypothalamic-pituitary-adrenal axis and neuro-autocrine mechanisms, it remains unclear how psychological stress relates to the pathogenesis of acne. In this study, we investigated the relationship between psychological stress and catecholamine in acne lesions from 18 patients with mild or moderate acne. The State-Trait Anxiety Inventory (STAI) revealed that all patients were anxious, with six having low anxiety and 12 high anxiety. Salivary α-amylase activity (sAA), which is regulated by the sympatho-adrenal medullary (SAM) system, positively correlated with the STAI State Anxiety scores (STAI-S) and was significantly detectable in acne patients with high rather than low anxiety. In addition, the level of normetanephrine, but not metanephrine, both of which are catecholamine metabolites, in hair follicles of acne lesions also positively correlated with the STAI-S. Furthermore, the normetanephrine level was higher in patients with high rather than low anxiety, whereas there was no change in metanephrine in the hair follicles of the acne lesions. Moreover, neither the sAA nor metanephrine and normetanephrine in the acne lesions was related to acne severity in the patients. Thus, these results provide novel evidence that a SAM system-associated increase of normetanephrine level in hair follicles is involved in the acne pathology of patients with anxiety.

Gene expression profile of human follicle dermal papilla cells in response to Camellia japonica phytoplacenta extract

Camellia japonica L. is a flowering tree with several medicinal and cosmetic applications. Here, we investigated the efficacy of C. japonica placenta extract (CJPE) as a potential therapeutic agent for promotion of hair growth and scalp health by using various in vitro and in vivo assays. Moreover, we performed transcriptome analysis to examine the relative expression of human follicle dermal papilla cells (HFDPC) in response to CJPE by RNA-sequencing (RNA-seq). In vitro assays revealed upregulation of the expression of hair growth marker genes in HFDPC after CJPE treatment. Moreover, in vivo clinical tests with 42 adult female participants showed that a solution containing 0.5% CJPE increased the moisture content of the scalp and decreased the scalp's sebum content, dead scalp keratin, and erythema. Furthermore, RNA-seq analysis revealed key genes in HFDPC which are associated with CJPE. Interestingly, genes associated with lipid metabolism and cholesterol efflux were upregulated. Genes upregulated by CJPE are associated with several hormones, including parathyroid, adrenocorticotropic hormone, α-melanocyte-stimulating hormone (alpha-MSH), and norepinephrine, which are involved in hair follicle biology. Furthermore, some upregulated genes are associated with the regulation of axon guidance. In contrast, many genes downregulated by CJPE are associated with structural components of the cytoskeleton. In addition, CJPE suppressed genes associated with muscle structure and development. Taken together, this study provides extensive evidence that CJPE may have potential as a therapeutic agent for scalp treatment and hair growth promotion.

Cigarette Smoking, Alcohol Consumption, and Risk of Alopecia Areata: A Population-Based Cohort Study in Taiwan

BACKGROUND

The effects of cigarette smoking and alcohol consumption on the risk of alopecia areata (AA) are unclear.

OBJECTIVE

The aim was to examine the association of cigarette smoking and alcohol consumption with AA.

METHODS

We collected participants from four rounds (2001, 2005, 2009, and 2013) of the Taiwan National Health Interview Survey. Incident AA cases were identified from the National Health Insurance database.

RESULTS

Of the 60,055 participants, 154 developed AA during the 647,902 person-years of follow-up. After controlling for confounders, current smokers had a higher risk of incident AA than never smokers [adjusted hazard ratio (aHR) 1.88; 95% confidence interval (CI) 1.22-2.88]. There was a trend toward an increased risk of AA with increasing numbers of years of smoking and cumulative pack-years of smoking among current smokers. The aHRs (95% CIs) of current smokers of > 5 and ≤ 15 cigarettes per day, > 10 and ≤ 20 years of smoking, ≤ 10, and > 10 and ≤ 20 pack-years of smoking were 2.03 (1.17-3.51), 2.25 (1.21-4.18), 1.86 (1.12-3.09), and 2.04 (1.04-4.01), respectively. Conversely, social and regular drinkers had significantly lower risks of AA than never drinkers [aHRs (95% CIs) 0.65 (0.43-0.98) and 0.49 (0.26-0.93), respectively].

CONCLUSION

Current smokers had an increased risk of developing AA, while alcohol consumption was associated with a decreased risk of AA.

Cell Types Promoting Goosebumps Form a Niche to Regulate Hair Follicle Stem Cells

Piloerection (goosebumps) requires concerted actions of the hair follicle, the arrector pili muscle (APM), and the sympathetic nerve, providing a model to study interactions across epithelium, mesenchyme, and nerves. Here, we show that APMs and sympathetic nerves form a dual-component niche to modulate hair follicle stem cell (HFSC) activity. Sympathetic nerves form synapse-like structures with HFSCs and regulate HFSCs through norepinephrine, whereas APMs maintain sympathetic innervation to HFSCs. Without norepinephrine signaling, HFSCs enter deep quiescence by down-regulating the cell cycle and metabolism while up-regulating quiescence regulators Foxp1 and Fgf18. During development, HFSC progeny secretes Sonic Hedgehog (SHH) to direct the formation of this APM-sympathetic nerve niche, which in turn controls hair follicle regeneration in adults. Our results reveal a reciprocal interdependence between a regenerative tissue and its niche at different stages and demonstrate sympathetic nerves can modulate stem cells through synapse-like connections and neurotransmitters to couple tissue production with demands.

Norepinephrine protects against apoptosis of mesenchymal stem cells induced by high glucose

In diabetes, the number of bone mesenchymal stem cells (MSCs) decreases and their differentiation is impaired. However, the exact mechanism is unclear. Patients with diabetes often experience sympathetic nerve injury. Norepinephrine (NE), a major mediator of the sympathetic nervous system, influences rat MSC migration in culture and in vivo. The present study aimed to investigate the effect of NE on MSCs under high glucose conditions; therefore MSCs were treated with high glucose and NE. High glucose-induced MSCs apoptosis, which was reversed by NE. To verify the effect of NE, mice underwent sympathectomy and were used to establish a diabetic model. Diabetic mice with sympathectomy had a higher apoptosis rate and higher levels of reactive oxygen species in their bone marrow-derived cells than diabetic mice without sympathectomy. High glucose inhibited p-AKT production and B-Cell CLL/Lymphoma 2 expression, and promoted BAX and caspase-3 expression. NE reversed these effects of high glucose. An AKT inhibitor enhanced the effects of high glucose. Thus, NE had a protective effect on MSC apoptosis induced by high glucose, possibly via the AKT/BCL-2 pathway.