BuShenYiQi Granule Inhibits Atopic Dermatitis via Improving Central and Skin Hypothalamic -Pituitary -Adrenal Axis Function

BackgroundDysfunction of central and skin Hypothalamic-Pituitary-Adrenal (HPA) axis play important roles in pathogenesis of atopic dermatitis (AD). Our previous studies showed that several Chinese herbs could improve HPA axis function. In this study, we evaluated the anti-inflammatory effects of BuShenYiQi granule (BSYQ), a Chinese herbs formula, in AD mice and explored the effective mechanism from regulation of HPA axis.MethodsThe ovalbumin (OVA) induced AD mice model were established and treated with BSYQ. We evaluated dermatitis score and histology analysis of dorsal skin lesions, meanwhile, serum corticosterone (CORT), adrenocorticotropic hormone (ACTH), corticotropin-releasing hormone (CRH) and inflammatory cytokines were determined by ELISA. The changes of CRH/proopiomelanocortin(POMC) axis elements, corresponding functional receptors and crucial genes of glucocorticosteroidogenesis in the skin were measured by quantitative real-time PCR and western blot, respectively.ResultsThe symptoms and pathological changes in skin of AD mice were significantly improved and several markers of inflammation and allergy descended obviously after BSYQ treatment. We found that AD mice had insufficient central HPA tone, but these conditions were markedly improved after BSYQ treatment. The AD mice also showed a disturbed expression of skin HPA. In lesion skin of AD mice, the mRNA and protein expressions of CRH decreased significantly, on the contrary, POMC and cytochrome P450 side-chain cleavage enzyme (CYP11A1) increased markedly, meanwhile, NR3C1 (mouse GR), CRHR2 and 11-hydroxylase type 1(CYP11B1) were reduced locally. Most of these tested indexes were improved after BSYQ treatment.ConclusionsAD mice displayed the differential expression pattern of central and skin HPA axis and BSYQ treatment significantly alleviated the symptoms of AD mice and presented anti-inflammatory and anti-allergic effects via regulating the expression of central and skin HPA axis.     

CRH stimulation of corticosteroids production in melanocytes is mediated by ACTH

The response to systemic stress is organized along the hypothalamic-pituitary-adrenal axis (HPA), whereas the response to a peripheral stress (solar radiation) is mediated by epidermal melanocytes (cells of neural crest origin) responsible for the pigmentary reaction. Melanocytes express proopiomelanocortin (POMC), corticotropin-releasing hormone (CRH), and CRH receptor-1 (CRH-R1) and can produce corticosterone. In the present study, incubation of normal epidermal melanocytes with CRH was found to trigger a functional cascade structured hierarchically and arranged along the same algorithm as in the HPA axis: CRH activation of CRH-R1 stimulated cAMP accumulation and increased POMC gene expression and production of ACTH. CRH and ACTH also enhanced production of cortisol and corticosterone, and cortisol production was also stimulated by progesterone. The chemical identity of the cortisol was confirmed by liquid chromatography-mass spectrometry (LC/MS2) with [corrected] mass spectrometry-mass spectrometry analyses. POMC gene silencing abolished the stimulatory effect of CRH on corticosteroid synthesis, indicating that this is indirect and mediated via production of ACTH. Thus the melanocyte response to CRH is highly organized along the same functional hierarchy as the HPA axis. This pattern demonstrates the fractal nature of the response to stress with similar activation sequence at the single-cell and whole body levels.     

Effects of corticotropin-releasing hormone on proopiomelanocortin derivatives and monocytic HLA-DR expression in patients with septic shock

Little is known about interactions between immune and neuro-endocrine systems in patients with septic shock. We therefore evaluated whether the corticotropin-releasing hormone (CRH) and/or proopiomelanocortin (POMC) derivatives [ACTH, β-endorphin (β-END), β-lipotropin (β-LPH), α-melanocyte stimulating hormone (α-MSH) or N-acetyl-β-END (Nac-β-END)] have any influences on monocyte deactivation as a major factor of immunosuppression under septic shock conditions. Sixteen patients with septic shock were enrolled in a double-blind, cross-over and placebo controlled clinical study; 0.5 μg/(kg_bodyweight h) CRH (or placebo) were intravenously administered for 24 h. Using flow cytometry we investigated the immunosuppression in patients as far as related to the loss of leukocyte surface antigen-DR expression on circulating monocytes (mHLA-DR). ACTH, β-END immunoreacive material (IRM), β-LPH IRM, α-MSH and Nac-β-END IRM as well as TNF-α and mHLA-DR expression were determined before, during and after treatment with CRH (or placebo). A significant correlation between plasma concentration of α-MSH and mHLA-DR expression and an inverse correlation between mHLA-DR expression and TNF-α plasma level were found. Additionally, a significant increase of mHLA-DR expression was observed 16 h after starting the CRH infusion; 8 h later, the mHLA-DR expression had decreased again. Our results indicate that the up-regulation of mHLA-DR expression after CRH infusion is not dependent on the release of POMC derivatives. From the correlation between plasma concentration of α-MSH and mHLA-DR expression, we conclude that in patients with septic shock the down-regulation of mHAL-DR expression is accompanied by the loss of monocytic release of α-MSH into the cardiovascular compartment.     

Prenatal exposure to dexamethasone alters hippocampal drive on hypothalamic-pituitary-adrenal axis activity in adult male rats

Glucocorticoids are essential for normal hypothalamic-pituitary-adrenal (HPA) axis activity; however, recent studies warn that exposure to excess endogenous or synthetic glucocorticoid during a specific period of prenatal development adversely affects HPA axis stability. We administered dexamethasone (DEX) to pregnant rats during the last week of gestation and investigated subsequent HPA axis regulation in adult male offspring in unrestrained and restraint-stressed conditions. With the use of real-time PCR and RIA, we examined the expression of regulatory genes in the hippocampus, hypothalamus, and pituitary, including corticotropin-releasing hormone (CRH), arginine vasopressin (AVP), glucocorticoid receptors (GR), mineralcorticoid receptors (MR), and 11-beta-hydroxysteroid dehydrogenase-1 (11beta-HSD-1), as well as the main HPA axis hormones, adrenal corticotropic hormone (ACTH) and corticosterone (CORT). Our results demonstrate that the DEX-exposed group exhibited an overall change in the pattern of gene expression and hormone levels in the unrestrained animals. These changes included an upregulation of CRH in the hypothalamus, a downregulation of MR with a concomitant upregulation of 11beta-HSD-1 in the hippocampus, and an increase in circulating levels of both ACTH and CORT relative to unrestrained control animals. Interestingly, both DEX-exposed and control rats exhibited an increase in pituitary GR mRNA levels following a 1-h recovery from restraint stress; however, the increased expression in DEX-exposed rats was significantly less and was associated with a slower return to baseline CORT compared with controls. In addition, circulating levels of ACTH and CORT as well as hypothalamic CRH and hippocampal 11beta-HSD-1 expression levels were significantly higher in the DEX-exposed group compared with controls following restraint stress. Taken together, these data demonstrate that late-gestation DEX exposure in rats is associated with persistent changes in both the modulation of HPA axis activity and the HPA axis-mediated response to stress.     

Comutagenesis of sodium arsenite with ultraviolet radiation in Chinese hamster V79 cells

Summary Solar ultraviolet radiation has been associated with the induction of skin cancer. Recent studies have indicated that near-ultraviolet, especially UVB, is mutagenic. Exposure to trivalent inorganic arsenic compounds has also been associated with increased skin cancer prevalence. Trivalent arsenic compounds are not mutagenicper se, but are comutagenic with a number of cancer agents. Here, we test the hypothesis that arsenite enhances skin cancer via its comutagenic action with solar ultraviolet radiation. Irradiation of Chinese hamster V79 cells with UVA (360 nm), UVB (310 nm) and UVC (254 nm) caused a fluence-dependent increase in mutations at thehprt locus. On an energy basis, UVC was the most mutagenic and UVA the least. However, when expressed as a function of toxicity, UVB was more mutagenic than UVC. Nontoxic concentrations of arsenite increased the toxicity of UVA, UVB and UVC. Arsenite acted as a comutagen at the three wavelengths; however, higher concentrations of arsenite were required to produce a significant (P < 0.05) comutagenic response with UVB. The increased mutagenicity of UVB and UVA by arsenite may play a role in arsenite-related skin cancers.     

Characterization of a ultraviolet B-induced corticotropin-releasing hormone-proopiomelanocortin system in human melanocytes

CRH, the main regulator of the systemic response to stress, is also expressed in the skin where it is incorporated into a local homolog of the hypothalamic-pituitary-adrenal axis. To investigate the mechanisms of the induction of the CRH-proopiomelanocortin (POMC) response in human melanocytes, we used UVB as an epidermal-specific stressor. Human normal melanocytes cultured in vitro were irradiated with graded doses of UVB, and the CRH-POMC responses were measured in cell extracts and/or supernatants. UVB stimulated the CRH promoter, the CRH mRNA expression, and peptide release. The UVB-induced stimulation of the CRH promoter was suppressed by pharmacological inhibitors of protein kinase A or by plasmid overexpressing a dominant mutant cAMP response element (CRE)-binding protein (CREB). UVB also stimulated phosphorylation of CREB, binding of phosphorylated CREB to CRE sites in the CRH promoter, and activity of the reporter gene construct driven by consensus CRE sites. Mutation in the CRE site in the CRH promoter rendered the corresponding reporter gene construct less responsive to UVB in both normal and malignant melanocytes. In addition to CRH effects, UVB activated the POMC promoter, POMC mRNA expression, and ACTH release, whereas an antagonist of the CRH receptor 1 abrogated the UVB-stimulated induction of POMC. In conclusion, UVB induces CRH production in human melanocytes through stimulation of the protein kinase A pathway, with sequential involvement of CRH-CRH receptor 1 in the stimulation of POMC expression.     

Ultraviolet radiation-induced photodegradation and 1O2, O2-. production by riboflavin, lumichrome and lumiflavin

Although UVA (320-400 nm) is considered less harmful to skin as compared to UVB (290-320 nm) and UVC (200-290 nm) radiation, certain endogenous chromophores may enhance UVA-induced cutaneous reactions by largely O2-dependent photodynamic reactions. Photodegradation pattern and singlet oxygen (1O2), superoxide anion radical (O2-.) producing capacity of riboflavin (RF), lumiflavin (LF) and lumichrome (LC) were examined to assess their phototoxic potential under UVA. Photolysis of RF upon exposure to UVA, UVB or UVC revealed considerable degradation to LF and LC with a near identical spectral pattern of photodegradation between 250-500 nm. Both LF and LC were stable to UVA (3 J/cm2) and UVB (400 mJ/cm2), whereas RF was photodegraded by 30 and 20%, respectively, under similar irradiation conditions. UVA-sensitized LF and LC respectively, produced nearly 15% higher and 60% lower yield of 1O2 in comparison to RF, whereas, O2-. was generated predominently by RF. Both RF and LF thus appeared to be potential chromophores for evoking deleterious effects of UVA in normal human skin.     

Wavelength dependence of biological damage induced by UV radiation on bacteria

The biological effects of UV radiation of different wavelengths (UVA, UVB and UVC) were assessed in nine bacterial isolates displaying different UV sensitivities. Biological effects (survival and activity) and molecular markers of oxidative stress [DNA strand breakage (DSB), generation of reactive oxygen species (ROS), oxidative damage to proteins and lipids, and the activity of antioxidant enzymes catalase and superoxide dismutase] were quantified and statistically analyzed in order to identify the major determinants of cell inactivation under the different spectral regions. Survival and activity followed a clear wavelength dependence, being highest under UVA and lowest under UVC. The generation of ROS, as well as protein and lipid oxidation, followed the same pattern. DNA damage (DSB) showed the inverse trend. Multiple stepwise regression analysis revealed that survival under UVA, UVB and UVC wavelengths was best explained by DSB, oxidative damage to lipids, and intracellular ROS levels, respectively.     

Cutaneous expression of corticotropin-releasing hormone (CRH), urocortin, and CRH receptors.

Studies in mammalian skin have shown expression of the genes for corticotropin-releasing hormone (CRH) and the related urocortin peptide, with subsequent production of the respective peptides. Recent molecular and biochemical analyses have further revealed the presence of CRH receptors (CRH-Rs). These CRH-Rs are functional, responding to CRH and urocortin peptides (exogenous or produced locally) through activation of receptor(s)-mediated pathways to modify skin cell phenotype. Thus, when taken together with the previous findings of cutaneous expression of POMC and its receptors, these observations extend the range of regulatory elements of the hypothalamic-pituitary-adrenal axis expressed in mammalian skin. Overall, the cutaneous CRH/POMC expression is highly reactive to common stressors such as immune cytokines, ultraviolet radiation, cutaneous pathology, or even the physiological changes associated with the hair cycle phase. Therefore, similar to its central analog, the local expression and action of CRH/POMC elements appear to be highly organized and entrained, representing general mechanism of cutaneous response to stressful stimuli. In such a CRH/POMC system, the CRH-Rs may be a central element.     

Mutagenic action of monochromatic UV radiation in the solar range on human cells

Mutations to ouabain resistance (selecting for base modifications at the co-dominant Na+K+-dependent ATP-ase locus) and thioguanine resistance (selecting for a wide range of genetic changes at the recessive hypoxanthine-guanine phosphoribosyl transferase locus) were measured in a repair-proficient human lymphoblastoid line with defined monochromatic radiations in the UVC (254 nm), UVB (302 nm, 313 nm), UVA (334 nm, 365 nm) and visible (405 nm) ranges. No mutations were detected at wavelengths in the range 334-405 nm. At 254 nm and 313 nm, both mutations to thioguanine resistance and survival were consistent with those expected from the relative levels of cyclobutane-type pyrimidine dimers induced. However, at 313 nm, the ratio of ouabain-resistant to thioguanine-resistant mutants is 10 times higher than at 254 nm, indicating that a unique type of pre-mutagenic base damage is induced at the longer wavelength. Radiation in the UVA (334 nm) range reduced the induction of mutations by a UVC (254 nm) wavelength at both mutation markers. These results suggest, first, that distinct types of biologically expressed genetic damage may be induced in the UVB region of sunlight and, second, that strong interactions may occur between the different wavelength regions of sunlight that can modify the expression of this genetic damage in human cells.     

Activation of mammalian gene expression by the UV component of sunlight – from models to reality

Ultraviolet radiation activates the expression of a wide variety of genes, by pathways which differ between the short non-solar ultraviolet C (UVC) wavelengths, which are strongly absorbed by nucleic acids, and the long solar ultraviolet A (UVA, 320–380 nm) wavelengths, which generate active oxygen intermediates. Intermediate solar ultraviolet (UV) wavelengths in the UVB (290–320 nm) range also contain an oxidative component, but more closely resemble UVC in their gene activating properties. Short wavelength UV, in common with other extracellular stimuli including growth factors, activates signal transduction events that involve both stress- and mitogen-activated protein kinase cascades. The extrapolation of the complex modulation of gene expression that ensues to the consequences of natural UV exposure requires careful attention to the details of doses and wavelength employed in the model experiments. Nevertheless, there is evidence that UVB irrradiation of skin can activate the expression of proteins including immunomodulating cytokines, ornithine decarboxylase and, to a limited extent, nuclear oncogene products, as well as lead to stabilisation of p53. Non-cytotoxic doses of UVA radiation also lead to the strong activation of several genes which would be expected to have functional relevance in vivo.     

Pleiotropic effects of corticotropin releasing hormone on normal human skin keratinocytes

The hypothalamic-pituitary-adrenal (HPA) axis is the major stress response system. Several components of the HPA axis, such as corticotropin-releasing hormone (CRH) and POMC peptides and their receptors are also present in the skin. In earlier studies, we showed that CRH inhibits cellular proliferation of immortalized human keratinocytes. We now examine further the functional activity of the HPA axis in the skin, by characterizing the actions of CRH on normal foreskin keratinocytes. The CRH receptor was detected as CRH-R1 antigen at 47 kDa in the cultured keratinocytes by Western blotting, and immunohistochemistry demonstrated its presence in the epidermal and follicular keratinocytes. CRH is also biologically active in cultured keratinocytes, where it inhibits proliferation and enhances the interferon-gamma-stimulated expression of the hCAM and ICAM-1 adhesion molecules and of the HLA-DR antigen. These effects were concentration-dependent, with maximal activity at CRH 10(-7) M. Thus, in the keratinocyte, the most important cellular component of the epidermis, CRH appears to induce a shift in energy metabolism away from proliferation activity, and toward the enhancement of immunoactivity. Therefore, similar to its central actions, cutaneous CRH may also he involved in the stress response, but at a highly localized level.     

Genetic variation of the cutaneous HPA axis: An analysis of UVB-induced differential responses

Mammalian skin incorporates a local equivalent of the hypothalamic–pituitary–adrenal (HPA) axis that is critical in coordinating homeostatic responses against external noxious stimuli. Ultraviolet radiation B (UVB) is a skin-specific stressor that can activate this cutaneous HPA axis. Since C57BL/6 (B6) and DBA/2J (D2) strains of mice have different predispositions to sensorineural pathway activation, we quantified expression of HPA axis components at the gene and protein levels in skin incubated ex vivo after UVB or sham irradiation. Urocortin mRNA was up-regulated after all doses of UVB with a maximum level at 50 mJ/cm² after 12 h for D2 and at 200 mJ/cm² after 24 h for B6. Proopiomelanocortin mRNA was enhanced after 6 h with the peak after 12 h and at 200 mJ/cm² for both genotypes of mice. ACTH levels in tissue and media increased after 24 h in B6 but not in D2. UVB stimulated β-endorphin expression was higher in D2 than in B6. Melanocortin receptor 2 mRNA was stimulated by UVB in a dose-dependent manner, with a peak at 200 mJ/cm² after 12 h for both strains. The expression of Cyp11a1 mRNA — a key mitochondrial P450 enzyme in steroidogenesis, was stimulated at all doses of UVB irradiation, with the most pronounced effect after 12–24 h. UVB radiation caused, independently of genotype, a dose-dependent increase in corticosterone production in the skin, mainly after 24 h of histoculture. Thus, basal and UVB stimulated expression of the cutaneous HPA axis differs as a function of genotype: D2 responds to UVB earlier and with higher amplitude than B6, while B6 shows prolonged (up to 48 h) stress response to a noxious stimulus such as UVB.     

Solar Ultraviolet and the Evolutionary History of Cyanobacteria

On the basis of photobiological, evolutionary, paleontological, paleoenvironmental and physiological arguments, a time course for the role of solar ultraviolet radiation (UVR, wavelengths below 400 nm) in the ecology and evolution of cyanobacteria is proposed in which three main periods can be distinguished. An initial stage, before the advent of oxygenic photosynthesis, when high environmental fluxes of UVC (wavelengths below 280 nm) and UVB (280–320 nm) may have depressed the ability of protocyanobacteria to develop large populations or restricted them to UVR refuges. A second stage lasting between 500 and 1500 Ma (million years), started with the appearance of true oxygen-evolving cyanobacteria and the concomitant formation of oxygenated (micro)environments under an oxygen free-atmosphere. In this second stage, the age of UV, the overall importance of UVR must have increased substantially, since the incident fluxes of UVC and UVB remained virtually unchanged, but additionally the UVA portion of the spectrum (320–400 nm) suddenly became biologically injurious and extremely reactive oxygen species must have formed wherever oxygen and UVR spatially coincided. The last period began with the gradual oxygenation of the atmosphere and the formation of the stratospheric ozone shield. The physiological stress due to UVC all but disappeared and the effects of UVB were reduced to a large extent. Evidence in support of this dynamics is drawn from the phylogenetic distribution of biochemical UV-defense mechanisms among cyanobacteria and other microorganisms. The specific physical characteristics of UVR and oxygen exposure in planktonic, sedimentary and terrestrial habitats are used to explore the plausible impact of UVR in each of the periods on the ecological distribution of cyanobacteria.     

CRH inhibits NF-kappa B signaling in human melanocytes

Corticotropin releasing hormone (CRH), a messenger of stress at the central level, is expressed in the epidermis where it operates within local equivalent of hypothalamo-pituitary axis. CRH inhibits NF-κB activity in human immortalized epidermal (PIG1) melanocytes. In melanocytes CRH stimulates pro-opiomelanocortin (POMC) mRNA and adrenocorticotropin (ACTH) peptide production. Knockdown of POMC levels by transfecting cells with antisense oligonucleotides blocks the effect of CRH on NF-κB signaling indicating that the above inhibition is indirect, e.g. through activation of POMC. We suggest that induction of POMC by CRH serves as a feedback mechanism to self-restrict inflammatory response in the skin.     

Genistein stimulates the hypothalamo-pituitary-adrenal axis in adult rats: morphological and hormonal study

Genistein, the soy isoflavone structurally similar to estradiol, is widely consumed for putative beneficial health effects. However, there is a lack of data about the genisteins' effects in adult males, especially its effects on the hipothalamo-pituitary-adrenal (HPA) axis. Therefore, the present study was carried out to investigate the effects of genistein on the HPA axis in orchidectomized adult rats, and to create a parallel with those of estradiol. Changes in the hypothalamic corticotrophin-releasing hormone (CRH) neurons and pituitary corticotrophs (ACTH cells) were evaluated stereologically, while corticosterone and ACTH levels were determined biochemically. Orchidectomy (Orx) provoked the enlargement (p<0.05) of: hypothalamic paraventricular nucleus volume (60%), percentage of CRH neurons (23%), percentage of activated CRH neurons (45%); pituitary weight (15%) and ACTH level (57%). In comparison with Orx, estradiol treatment provoked the enlargement (p<0.05) of: percentage of CRH neurons (28%), percentage of activated CRH neurons (2.7-fold), pituitary weight (131%) and volume (82%), ACTH level (69%), the serum (103%) and adrenal tissue (4.8 fold) level of corticosterone. Clearly, Orx has induced the increase in HPA axis activity, which even augments after estradiol treatment. Also, compared to Orx, genistein treatment provoked the enhancement (p<0.05) of: percentage of activated CRH neurons (2.3-fold), pituitary weight (28%) and volume (21%), total number of ACTH cells (22%) ACTH level (45%), the serum (2.6-fold) and adrenal tissue (2.8 fold) level of corticosterone. It can be concluded that an identical tendency, concerning the HPA axis parameters, follows estradiol and genistein administration to the orchidectomized adult rats.     

Honokiol Exerts Antidepressant Effects in Rats Exposed to Chronic Unpredictable Mild Stress by Regulating Brain Derived Neurotrophic Factor Level and Hypothalamus–Pituitary–Adrenal Axis Activity

Honokiol (HNK), the main active component of Magnolia officinalis, has shown a variety of pharmacological activities. In the present study, we measured the antidepressant-like effects of HNK in a rat model of chronic unpredictable mild stress (CUMS) and explored its possible mechanisms. The antidepressant-like effects of HNK were assessed in rats by an open field test (OFT), sucrose preference test (SPT) and forced swimming test (FST). Then, serum levels of corticotrophin-releasing hormone (CRH), adrenocorticotropic hormone (ACTH) and corticosterone (CORT) and hippocampal brain-derived neurotrophic factor (BDNF) and glucocorticoid receptor α (GRα) levels were assessed to explore the possible mechanisms. We identified that HNK treatment (2, 4, and 8 mg/kg) alleviated the CUMS-induced behavioural deficits. Treatment with HNK also normalized the CUMS-induced hyperactivity of the limbic hypothalamic–pituitary–adrenal (HPA) axis, as indicated by reduced CRH, ACTH and CORT serum levels. In addition, HNK increased the expression of GRα (mRNA and protein) and BDNF (mRNA and protein) in the hippocampus. These data confirmed the antidepressant-like effects of HNK, which may be related to its normalizing the function of the HPA axis and increasing the BDNF level in the hippocampus.