Corticotropin-releasing hormone attenuates vascular endothelial growth factor release from human HaCaT keratinocytes

Stress and Nasal Allergy: Corticotropin-Releasing Hormone Stimulates Mast Cell Degranulation and Proliferation in Human Nasal Mucosa

Psychological stress exacerbates mast cell (MC)-dependent inflammation, including nasal allergy, but the underlying mechanisms are not thoroughly understood. Because the key stress-mediating neurohormone, corticotropin-releasing hormone (CRH), induces human skin MC degranulation, we hypothesized that CRH may be a key player in stress-aggravated nasal allergy. In the current study, we probed this hypothesis in human nasal mucosa MCs (hM-MCs) in situ using nasal polyp organ culture and tested whether CRH is required for murine M-MC activation by perceived stress in vivo. CRH stimulation significantly increased the number of hM-MCs, stimulated both their degranulation and proliferation ex vivo, and increased stem cell factor (SCF) expression in human nasal mucosa epithelium. CRH also sensitized hM-MCs to further CRH stimulation and promoted a pro-inflammatory hM-MC phenotype. The CRH-induced increase in hM-MCs was mitigated by co-administration of CRH receptor type 1 (CRH-R1)-specific antagonist antalarmin, CRH-R1 small interfering RNA (siRNA), or SCF-neutralizing antibody. In vivo, restraint stress significantly increased the number and degranulation of murine M-MCs compared with sham-stressed mice. This effect was mitigated by intranasal antalarmin. Our data suggest that CRH is a major activator of hM-MC in nasal mucosa, in part via promoting SCF production, and that CRH-R1 antagonists such as antalarmin are promising candidate therapeutics for nasal mucosa neuroinflammation induced by perceived stress.

Stress-induced Interaction of Skin Immune Cells, Hormones, and Neurotransmitters

PURPOSE

Although scientific articles mention the impact of psychological stress on skin diseases, few review the latest research on factors involved in this correlation. The skin actively responds to psychological stress, with involvement of skin immune cells, hormones, neurotransmitters. Skin immune cells actively regulate tissue inflammation with their proinflammatory and anti-inflammatory effects. Stress-induced skin reactions primarily include cytokine secretion (e.g. interleukin-6, interleukin-1, interferon-γ) and activation of skins peripheral corticotropin-releasing hormone (CRH)-proopiomelanocortin (POMC)-adrenocorticotropic hormone (ACTH)-corticosteroids axis, which leads to acute/chronic secretion of corticosteroids in the skin.

METHODS

This narrative review presents the current knowledge and latest findings regarding the impact of psychological stress on skin diseases, including information concerning psychoneuroimmune factors in stress-induced skin responses. Recent articles published in English available through the PubMed database and other prominent literature are discussed.

FINDINGS

Stress mediators, including cortisol, ACTH, and CRH from hypothalamus-pituitary-adrenal axis activation, induce various skin immune responses. Skin cells themselves can secrete these hormones and participate in skin inflammation. Thus, the local skin CRH-POMC-ACTH-corticosteroids axis plays a prominent role in stress-induced responses. Also, keratinocytes and fibroblasts produce hypothalamic and pituitary signal peptides and express receptors for them (CRH with receptors and POMC degradation peptides with melanocortin receptors), which allows them to respond to CRH by activating the POMC gene, which is then followed by ACTH and subsequently corticosteroids excretion. In addition, keratinocytes can express receptors for neurotransmitters (e.g. adrenaline, noradrenaline, dopamine, histamine, acetylcholine), neurotrophins, and neuropeptides (e.g. substance P, nerve growth factor), which are important in linking psychoneuroimmunologic mechanisms.

IMPLICATIONS

Psychoneuroimmunology provides an understanding that the skin is target and source of stress mediators. This locally expressed complex stress-induced network has been confirmed as active in many skin diseases (e.g. vulgar psoriasis, atopic dermatitis, chronic urticaria, human papillomavirus infections/warts, hair loss, acne). Skin reactions to stress and its influence on skin diseases may have implications for disease severity and exacerbation frequency, given the effect of locally secreted corticosteroids and other mediators that affect skin integrity, inflammation, and healing potential. Studies have also shown that introducing psychiatric treatment (drugs or psychotherapeutic methods) can have positive effects on dermatologic diseases influenced by psychological stress exposure. We hope this review provides clinicians and scientists with more complete background for further research in this field of skin psychoneuroimmunology.

Association between Stress and the HPA Axis in the Atopic Dermatitis

The hypothalamic–pituitary–adrenal (HPA) axis is one of the body’s neuroendocrine networks that responds to psychological stress (PS). In the skin, there exists a peripheral HPA axis similar to the central axis. Glucocorticoids (GCs) are key effector molecules of the HPA axis and are essential for cutaneous homeostasis. Atopic dermatitis (AD) is a condition typically characterized by a chronic relapsing course that often results in PS. HPA dysfunction is present in AD patients by the decreased response of GCs elevation to stress as compared to those unaffected by AD. Nevertheless, in skin, acute PS activates several metabolic responses that are of immediate benefit to the host. During the acute phase of PS, increased endogenous GCs have been shown to provide benefit rather than by aggravating cutaneous inflammatory dermatoses. However, a chronic T helper cell type 2 (Th2) predominant cytokine profile acts as a negative feedback loop to blunt the HPA axis response in AD. In this article, we reviewed the role of CRF, pro-opiomelanocortin (POMC)-derived peptides, GCs of the HPA, and 11β-hydroxysteroid dehydrogenase 1 (11β-HSD1) in AD, with a discussion of the pathogenetic mechanisms of inflammation and skin barrier functions, including antimicrobial defense, and their association with PS.

A comparison of left and right atrial fibroblasts reveals different collagen production activity and stress-induced mitogen-activated protein kinase signalling in rats

AIM

Atrial fibrosis plays a pivotal role in the pathophysiology of heart failure (HF). The left atrium (LA) experiences greater fibrosis than the right atrium (RA) during HF. It is not clear whether LA cardiac fibroblasts contain distinctive activities that predispose LA to fibrosis.

METHODS

LA and RA fibrosis were evaluated in healthy and isoproterenol-induced HF Sprague Dawley rats. Rat LA and RA primary isolated fibroblasts were subjected to proliferation assay, oxidative stress assay, cell migration analysis, collagen measurement, cytokine array and Western blot.

RESULTS

Healthy rat LA and RA had a similar extent of collagen deposition. HF significantly increased fibrosis to a greater severity in LA than in RA. Compared to isolated RA fibroblasts, the in vitro experiments showed that isolated LA fibroblasts had higher oxidative stress and exhibited higher collagen, transforming growth factor-β1, connective tissue growth factor production and less vascular endothelial growth factor (VEGF) production, but had similar migration, myofibroblast differentiation and proliferation activities. VEGF significantly increased the collagen production ability of LA fibroblasts, but not RA fibroblasts. LA fibroblasts had more phosphorylated ERK1/2 and P38 expression. ERK inhibitor (PD98059, 50 μmol L^-1 ) significantly attenuated collagen production and increased VEGF production in RA fibroblasts but not in LA fibroblasts. P38 inhibitor (SB203580, 30 μmol L^-1 ) significantly attenuated collagen production in LA fibroblasts but not in RA fibroblasts. P38 inhibitor also significantly increased VEGF production in RA and LA fibroblasts.

CONCLUSIONS

Differences in profibrotic activity between LA and RA fibroblasts may be caused by different responses to mitogen-activated protein kinase signalling.

Inhibiting interleukin-18 production through the mitogen-activated protein kinase pathway, a potential role of corticotropin-releasing hormone in chronic plaque psoriasis

Corticotropin-releasing hormone (CRH) and CRH receptors (CRH-Rs) are expressed in the skin; CRH-R1 is the predominant receptor. Whether the CRH/CRH-R1 system plays a role in psoriasis has not yet been assessed. Immunohistochemistry, real-time RT-PCR, ELISA assay, and Western blot analysis were used to investigate the expression of CRH/CRH-R1 in patients with chronic plaque psoriasis and that of IL-18 in CRH-treated HaCaT cells. CRH and CRH-R1 were downregulated in patients with chronic plaque psoriasis. In vitro, CRH attenuated the expression of IL-18 by a mitogen-activated protein kinase signaling pathway through CRH-R1 in HaCaT cells. Thus, an aberrant cutaneous CRH/CRH-R1 system exists in lesions from chronic plaque psoriasis which might play a role in psoriasis and offers further evidence for the study of CRH in the skin.

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.

Key role of CRF in the skin stress response system

The discovery of corticotropin-releasing factor (CRF) or CRH defining the upper regulatory arm of the hypothalamic-pituitary-adrenal (HPA) axis, along with the identification of the corresponding receptors (CRFRs 1 and 2), represents a milestone in our understanding of central mechanisms regulating body and local homeostasis. We focused on the CRF-led signaling systems in the skin and offer a model for regulation of peripheral homeostasis based on the interaction of CRF and the structurally related urocortins with corresponding receptors and the resulting direct or indirect phenotypic effects that include regulation of epidermal barrier function, skin immune, pigmentary, adnexal, and dermal functions necessary to maintain local and systemic homeostasis. The regulatory modes of action include the classical CRF-led cutaneous equivalent of the central HPA axis, the expression and function of CRF and related peptides, and the stimulation of pro-opiomelanocortin peptides or cytokines. The key regulatory role is assigned to the CRFR-1α receptor, with other isoforms having modulatory effects. CRF can be released from sensory nerves and immune cells in response to emotional and environmental stressors. The expression sequence of peptides includes urocortin/CRF→pro-opiomelanocortin→ACTH, MSH, and β-endorphin. Expression of these peptides and of CRFR-1α is environmentally regulated, and their dysfunction can lead to skin and systemic diseases. Environmentally stressed skin can activate both the central and local HPA axis through either sensory nerves or humoral factors to turn on homeostatic responses counteracting cutaneous and systemic environmental damage. CRF and CRFR-1 may constitute novel targets through the use of specific agonists or antagonists, especially for therapy of skin diseases that worsen with stress, such as atopic dermatitis and psoriasis.

VEGF plasma level variations in duloxetine-treated patients with major depression

BACKGROUND

The vascular endothelial growth factor (VEGF) signaling, which modulates angiogenesis and neurogenesis within the neurovascular unit, might play an important role in the neuro-endocrine-immune (NEI) stress-adaptation system. Recent evidence suggests that VEGF is involved in the pathophysiology of a number of diseases including major depressive disorder (MDD) and is affected by some treatments, including antidepressants. The objective of the study was to investigate the VEGF level variations in MDD patients during antidepressant treatment with duloxetine, a relatively new SNRI.

METHODS

A total of 30 MDD patients and 32 healthy controls were assessed using the Hamilton Depression Scale (HAM-D) and monitored for VEGF plasma levels at baseline, week 6 and week 12 of duloxetine treatment (60 mg/day) and at baseline, respectively.

RESULTS

According to early clinical response to duloxetine (defined at week 6 by reduction>50% of baseline HAM-D score), the MDD patients were divided into early responders (ER) and early non-responders (ENR). During duloxetine treatment, we found an opposite trend in the VEGF levels between ER and ENR: in ER the VEGF levels significantly increased in association with clinical response at W6, while in ENR the VEGF levels significantly decreased in association with an overall clinical response at W12.

LIMITATIONS

Small sample size.

CONCLUSIONS

The opposite trends in VEGF levels, increasing in ER and decreasing in ENR, might reflect differential Norepinephrine/Serotonin effects of duloxetine on differential neurobiological backgrounds of depressive syndromes. Overall, the modulation of VEGF signaling within the neurovascular unit during antidepressant treatment could hypothetically favor the remodeling of neural circuitry, contributing to adaptive adjustment of the NEI stress-adaptation system.

The chemokine CXCL12 and its receptor CXCR4 promote glioma stem cell-mediated VEGF production and tumour angiogenesis via PI3K/AKT signalling

Chemokines and their receptors are actively involved in inflammation, immune responses, and cancer development. Here we report the detection of CD133(+) glioma stem-like cells (GSCs) co-expressing a chemokine receptor CXCR4 in human primary glioma tissues. These GSCs were located in areas adjacent to tumour vascular capillaries, suggesting an association between GSCs and tumour angiogenesis. To test this hypothesis, we isolated CD133(+) GSCs from surgical specimens of human primary gliomas and glioma cell lines. As compared to CD133(-) cells, CD133(+) GSCs expressed significantly higher levels of CXCR4 mRNA and protein, and migrated more efficiently in response to the CXCR4 ligand CXCL12. In addition, CXCL12 induced vascular endothelial growth factor (VEGF) production by CD133(+) GSCs via activation of the PI3K/AKT signalling pathway. Furthermore, knocking down of CXCR4 using RNA interference or inhibition of CXCR4 function by an antagonist AMD3100 not only reduced VEGF production by CD133(+) GSCs in vitro, but also attenuated the growth and angiogenesis of tumour xenografts in vivo formed by CD133(+) GSCs in SCID mice. These results indicate that CXCL12 and its receptor CXCR4 promote GSC-initiated glioma growth and angiogenesis by stimulating VEGF production.

Effect of psoriasis therapy on VEGF and its soluble receptors serum concentrations

BACKGROUND

Vascular endothelial growth factor (VEGF) is recognized a pivotal pro-angiogenic factor responsible for new blood vessels formation in psoriatic lesion.

OBJECTIVES

The aim of the study was to analyse serum concentrations of VEGF and its soluble receptors (sVEGF) R1 and R2 in psoriatic patients before and after treatment.

METHODS

Serum samples were collected before and after 14 days of standard topical therapy, from 44 patients with exacerbated chronic plaque-type psoriasis and VEGF, sVEGF R1 and sVEGF R2 concentrations were measured using an enzyme immunoassay. Data were analysed with respect to baseline values of the psoriasis area severity index (PASI).

RESULTS

Baseline mean serum levels of VEGF and sVEGF R1, but not sVEGF R2 were significantly higher in patients than in healthy controls. VEGF demonstrated significant correlation with PASI score. Treatment resulted in significant reduction of VEGF serum concentration, particularly in patients with severe course of the disease (PASI >20) and increase in sVEGF R1 concentration in patients with mild disease activity (PASI <10). Moreover, serum sVEGF R1 level after treatment termination was significantly higher in patients with mild than severe course of psoriasis.

CONCLUSIONS

We confirmed the association between psoriasis activity and serum VEGF concentrations, which can be recognized as an indicator of the disease severity. However, the increase of serum sVEGF R1 concentrations can predict amelioration of clinical signs.

Effect of psoriasis activity on VEGF and its soluble receptors concentrations in serum and plaque scales

Vascular endothelial growth factor (VEGF) demonstrating pro-angiogenic activity promote new blood vessel formation in psoriatic lesions. The aim of this study was to evaluate the serum concentrations of VEGF, its soluble receptors (sVEGF R1 and R2) and VEGF content in scales of patients with psoriasis. To analyze possible association with activity of the disease, serum and scales from plaques were collected from 59 patients with exacerbated chronic plaque-type psoriasis. Mean concentrations of VEGF and sVEGF R1 in sera of patients were respectively two and four times higher than in healthy controls. Serum VEGF and sVEGF R1, but not sVEGF R2 demonstrated significant correlation with psoriasis area and severity index (PASI). There was also significant correlation between VEGF levels in serum and scales. Serum sVEGF R1 concentration was significantly elevated even in patients with low psoriasis activity (PASI<10), whereas increase of serum VEGF became significant in patients with medium activity (PASI: 10-20). Levels of serum VEGF and sVEGF R1 were the highest in patients with PASI>20. We confirmed association of both serum and scales VEGF concentrations with degree of psoriasis activity and demonstrated predominant increase of sVEGF R1 vs. VEGF in serum of patients with low psoriasis activity.