The protective effects of melatonin against water avoidance stress-induced mast cell degranulation in dermis

Psychodermatology of Chronic Pruritus: An Overview of the Link Between Itch and Distress

Chronic pruritus (CP) is defined as an unpleasant sensation causing a desire to scratch and lasting > 6 weeks. It has a multifactorial etiology but is more frequently associated with chronic inflammatory dermatoses and systemic disorders. Psychogenic pruritus and neurological disorders are other less common etiologies, while, in some patients, it is idiopathic. CP appears to be processed by non-histaminergic pathway, contributing to its complexity and therapeutic challenge. Moreover, regardless of the etiology, it is multidimensional, including cognitive, motivational and affective components. There is a close link between psychological distress and pruritus, with particular clinical expression in chronic inflammatory dermatoses, involving the activation of the hypothalamic-pituitary-adrenal axis (and its cutaneous equivalent), the sympathetic nervous system, the release of hormones and peptides, the role of immune cells (T and B cells, macrophages) and immune-related cells in the skin (mast cells, dendritic cells and keratinocytes). Moreover, there is strong evidence that psychological factors influence the experience of pruritus. CP can also cause psychiatric disorders, including but not limited to anxiety and depression, and also lead to significant quality of life (QoL) impairment. Thereby, although a psychodermatological assessment should ideally be carried out in the context of a specific psychodermatology consultation, a brief mental health assessment could be part of the general dermatological approach to these patients. Considering that mental health, QoL and pruritus are closely linked, psychotherapeutic interventions and/or psychotropic drugs should thus be considered in some patients as an adjunct to the pharmacological treatment of CP.

The effects of alpha-lipoic acid (ALA) on the urinary bladder injury in rats exposed to chronic stress: A histochemical study

Objective: In the present study, we aimed to investigate the morphological and biochemical effects of alpha-lipoic acid (ALA) on bladder injury caused by water avoidance stress (WAS) and to show its effect on the number of degranulated mast cells, which increase after stress. Materials and Methods: Wistar albino rats were subjected to WAS and the animals in the treatment group were injected ALA. After the urinary bladder tissues were subjected to routine tissue processing, hematoxylin-eosin staining and periodic acid-Schiff reaction were applied to observe general morphology and acidic toluidine blue method to investigate mast cells. Biochemical assessments of malondialdehyde (MDA) and glutathione (GSH) were also obtained. Transmission electron microscope was used for the ultrastructural, and scanning electron microscope for the topographical analyses. Results: The experiments showed that chronic stress caused injury in the bladder, increased degranulated and total number of mast cells and decreased GSH and increased MDA levels. ALA treatment after WAS ameliorated bladder injury in most areas, decreased degranulated and total mast cell number and increased GSH and decreased MDA levels. Conclusion: It was concluded that ALA can be a useful agent in the treatment of interstitial cystitis.

Psycho-Neuro-Endocrine-Immunology: A Role for Melatonin in This New Paradigm

Psychoneuroendocrinoimmunology is the area of study of the intimate relationship between immune, physical, emotional, and psychological aspects. This new way of studying the human body and its diseases was initiated in the last century’s first decades. However, the molecules that participate in the communication between the immune, endocrine, and neurological systems are still being discovered. This paper aims to describe the development of psychoneuroendocrinoimmunology, its scopes, limitations in actual medicine, and the extent of melatonin within it.

The Association between Melatonin Levels and Sleep Quality in Patients with Pruritus: A Potential Biomarker on a Candidate Future Treatment

Background:

Melatonin is a hormone that regulates the sleep–wake cycle and has immunomodulatory and anti-inflammatory roles.

Aims:

The aim of this study is to assess melatonin levels and investigate the association with pruritus severity, sleep quality, and depressive symptoms in dermatoses with nocturnal pruritus.

Methods:

The study was a prospective study with 82 participants, including 41 patients and 41 healthy volunteers. The visual analog scale (VAS), Pittsburg Sleep Quality Index (PSQI), and Beck Depression Inventory (BDI) were recorded for each patient. To assess the melatonin levels, urinary 6-sulfatoxymelatonin levels in the first urine in the morning were measured.

Results:

Melatonin concentrations were significantly lower (P = 0.007), while the BDI (P = 0.001) and PSQI (P = 0.001) scores were significantly higher in the patients with pruritus than in the healthy control subjects. There was an inverse correlation between melatonin levels and PSQI scores (r = −0.355, P = 0.023), and a positive correlation was detected between BDI scores and PSQI scores (r = 0.631, P = 0.001) in the pruritus group.

Conclusion:

Melatonin levels were found to decrease in relation to sleep quality in nocturnal pruritus patients. Low melatonin levels in these patients may be associated with sleep disorders and pruritus.

Nutraceutical Aid for Allergies - Strategies for Down-Regulating Mast Cell Degranulation

Interactions of antigens with the mast cell FcεRI-IgE receptor complex induce degranulation and boost synthesis of pro-inflammatory lipid mediators and cytokines. Activation of spleen tyrosine kinase (Syk) functions as a central hub in this signaling. The tyrosine phosphatase SHP-1 opposes Syk activity; stimulation of NADPH oxidase by FcεRI activation results in the production of oxidants that reversibly inhibit SHP-1, up-regulating the signal from Syk. Activated AMPK can suppress Syk activation by the FcεRI receptor, possibly reflecting its ability to phosphorylate the FcεRI beta subunit. Cyclic GMP, via protein kinase G II, enhances the activity of SHP-1 by phosphorylating its C-terminal region; this may explain its inhibitory impact on mast cell activation. Hydrogen sulfide (H2S) likewise opposes mast cell activation; H2S can boost AMPK activity, up-regulate cGMP production, and trigger Nrf2-mediated induction of Phase 2 enzymes - including heme oxygenase-1, whose generation of bilirubin suppresses NADPH oxidase activity. Phycocyanobilin (PCB), a chemical relative of bilirubin, shares its inhibitory impact on NADPH oxidase, rationalizing reported anti-allergic effects of PCB-rich spirulina ingestion. Phase 2 inducer nutraceuticals can likewise oppose the up-regulatory impact of NADPH oxidase on FcεRI signaling. AMPK can be activated with the nutraceutical berberine. High-dose biotin can boost cGMP levels in mast cells via direct stimulation of soluble guanylate cyclase. Endogenous generation of H2S in mast cells can be promoted by administering N-acetylcysteine and likely by taurine, which increases the expression of H2S-producing enzymes in the vascular system. Mast cell stabilization by benifuuki green tea catechins may reflect the decreased surface expression of FcεRI.

Topical Administration of Melatonin-Loaded Extracellular Vesicle-Mimetic Nanovesicles Improves 2,4-Dinitrofluorobenzene-Induced Atopic Dermatitis

Atopic dermatitis (AD) is caused by multiple factors that trigger chronic skin inflammation, including a defective skin barrier, immune cell activation, and microbial exposure. Although melatonin has an excellent biosafety profile and a potential to treat AD, there is limited clinical evidence from controlled trials that support the use of melatonin as an AD treatment. The delivery of melatonin via the transdermal delivery system is also a challenge in designing melatonin-based AD treatments. In this study, we generated melatonin-loaded extracellular vesicle-mimetic nanoparticles (MelaNVs) to improve the transdermal delivery of melatonin and to evaluate their therapeutic potential in AD. The MelaNVs were spherical nanoparticles with an average size of 100 nm, which is the optimal size for the transdermal delivery of drugs. MelaNVs showed anti-inflammatory effects by suppressing the release of TNF-α and β-hexosaminidase in LPS-treated RAW264.7 cells and compound 48/80-treated RBL-2H3 cells, respectively. MelaNVs showed a superior suppressive effect compared to an equivalent concentration of free melatonin. Treating a 2,4-dinitrofluorobenzene (DNCB)-induced AD-like mouse model with MelaNVs improved AD by suppressing local inflammation, mast cell infiltration, and fibrosis. In addition, MelaNVs effectively suppressed serum IgE levels and regulated serum IFN-γ and IL-4 levels. Taken together, these results suggest that MelaNVs are novel and efficient transdermal delivery systems of melatonin and that MelaNVs can be used as a treatment to improve AD.

The interplay between mast cells, pineal gland, and circadian rhythm: Links between histamine, melatonin, and inflammatory mediators

Our daily rhythmicity is controlled by a circadian clock with a specific set of genes located in the suprachiasmatic nucleus in the hypothalamus. Mast cells (MCs) are major effector cells that play a protective role against pathogens and inflammation. MC distribution and activation are associated with the circadian rhythm via two major pathways, IgE/FcεRI- and IL-33/ST2-mediated signaling. Furthermore, there is a robust oscillation between clock genes and MC-specific genes. Melatonin is a hormone derived from the amino acid tryptophan and is produced primarily in the pineal gland near the center of the brain, and histamine is a biologically active amine synthesized from the decarboxylation of the amino acid histidine by the L-histidine decarboxylase enzyme. Melatonin and histamine are previously reported to modulate circadian rhythms by pathways incorporating various modulators in which the nuclear factor-binding near the κ light-chain gene in B cells, NF-κB, is the common key factor. NF-κB interacts with the core clock genes and disrupts the production of pro-inflammatory cytokine mediators such as IL-6, IL-13, and TNF-α. Currently, there has been no study evaluating the interdependence between melatonin and histamine with respect to circadian oscillations in MCs. Accumulating evidence suggests that restoring circadian rhythms in MCs by targeting melatonin and histamine via NF-κB may be promising therapeutic strategy for MC-mediated inflammatory diseases. This review summarizes recent findings for circadian-mediated MC functional roles and activation paradigms, as well as the therapeutic potentials of targeting circadian-mediated melatonin and histamine signaling in MC-dependent inflammatory diseases.

The effects of melatonin administration on disease severity and sleep quality in children with atopic dermatitis: A randomized, double-blinded, placebo-controlled trial

BACKGROUND

The aim of this clinical trial was to determine the effects of melatonin administration on disease severity and sleep quality in children diagnosed with atopic dermatitis (AD).

METHODS

This randomized, double-blinded, placebo-controlled trial was conducted by recruiting 70 patients, aged 6-12 years, who had been diagnosed with AD. Study participants were randomly allocated into two intervention groups to receive either 6 mg/d melatonin supplements or placebo (n = 35 each group) for 6 weeks. Severity of disease was assessed using the scoring atopic dermatitis (SCORAD) and objective SCORAD indices. Sleep quality was evaluated by completing the Children's Sleep Habits Questionnaire (CSHQ).

RESULTS

Following 6 weeks of intervention, melatonin supplementation significantly improved SCORAD index (β -3.55; 95% CI, -6.11, -0.98; P = 0.007), objective SCORAD index (β -3.23; 95% CI, -5.08, -1.38; P = 0.001), serum total IgE levels (β -153.94 ku/L; 95% CI, -260.39, -47.49; P = 0.005), and CSHQ scores (β -2.55; 95% CI, -4.34, -0.75; P = 0.006). However, melatonin had no significant impact on pruritus scores, high-sensitivity C-reactive protein (hs-CRP), sleep-onset latency, total sleep time, weight, and BMI compared with placebo.

CONCLUSIONS

Overall, melatonin supplementation had beneficial effects on disease severity, serum total IgE levels, and CSHQ among children diagnosed with AD.

Effects of melatonin on acetylsalicylic acid induced gastroduodenal and jejunal mucosal injury

We evaluated the effects of melatonin on acetylsalicylic acid (ASA) induced gastroduodenal and jejunal mucosal injury. We used 40 postpubertal rats divided randomly into five groups of eight animals. The control group consisted of untreated animals. The Mel group was injected intraperitoneally (i.p.) with 5 mg/kg melatonin. The ASA group was injected i.p. with 200 mg/kg ASA. The ASA + Mel group was injected i.p. with 5 mg/kg melatonin 45 min after administering 200 mg/kg ASA i.p. The Mel + ASA group was injected i.p. with 5 mg/kg melatonin 45 min before administering 200 mg/kg ASA i.p. We found no statistically significant differences in mean histopathological scores in the ASA + Mel group compared to the ASA group. ASA caused shortened villi and loss of the apical villus in the duodenum. The histopathological score was increased and villus height was decreased in the ASA group compared to untreated controls. Treatment with melatonin attenuated the histological damage. In the ASA group, occasional areas showed erosion of villi in the jejunum; however, differences in mean histopathological score in ASA group compared to the other groups were not statistically significant. Malondialdehyde (MDA), glutathione (GSH) and superoxide dismutase (SOD) activities were measured in stomach, duodenal and jejunum tissue. We found increased MDA activity in both stomach and duodenal tissues in the ASA group compared to the control group (p < 0.05). We found no statistically significant changes in MDA levels in jejunal tissue in the ASA group compared to the control group. We found no change in SOD activity in either stomach or duodenal tissues in the ASA group compared to the control group. We observed decreased SOD activity in jejunal tissue in the ASA group compared to the control group (p < 0.05). We detected no change in GSH activity in stomach, duodenal or jejunal tissues in the ASA group compared to the control group. The stomach damage was less in melatonin treated groups, but the lesions were not completely eliminated. The jejunum in the ASA group retained a nearly normal appearance. We found that melatonin exhibited some healing effects on ASA induced duodenal mucosal injury.

Chronic restraint stress exacerbates nociception and inflammatory response induced by bee venom in rats: the role of the P2X7 receptors

OBJECTIVE

Chronic restraint stress exacerbates pain and inflammation. The present study was designed to evaluate the effect of chronic restraint stress on inflammatory pain induced by subcutaneous injection of bee venom (BV).

METHODS

First, we investigated: (1) the effect of two-week restraint stress with daily 2 or 8 h on the baseline paw withdrawal mechanical threshold (PWMT), paw withdrawal thermal latency (PWTL) and paw circumference (PC); (2) the effect of chronic stress on the spontaneous paw-flinching reflex (SPFR), decrease in PWM, PWTL and increase in PC of the injected paw induced by BV.

RESULTS

The results showed that (1) chronic restraint decreased significantly the PWMT and inhibited significantly the increase in PC, but had no effect on PWTL, compared with control group; (2) chronic restraint enhanced significantly BV-induced SPFR and inflammatory swelling of the injected paw. In a second series of experiments, the role of P2X7 receptor (P2X7R) in the enhancement of BV-induced inflammatory pain produced by chronic restraint stress was determined. Systemic pretreatment with P2X7R antagonist completely reversed the decrease in PWMT produced by chronic restraint, inhibited significantly the enhancement of BV-induced inflammatory pain produced by chronic restraint stress.

CONCLUSION

Taken together, our data indicate that chronic restraint stress-enhanced nociception and inflammation in the BV pain model, possibly involving the P2X7R.

Possible Involvement of the Inhibition of NF-κB Factor in Anti-Inflammatory Actions That Melatonin Exerts on Mast Cells

Melatonin is a molecule endogenously produced in a wide variety of immune cells, including mast cells (RBL-2H3). It exhibits immunomodulatory, anti-inflammatory and anti-apoptotic properties. The physiologic mechanisms underlying these activities of melatonin have not been clarified in mast cells. This work is designed to determine the anti-inflammatory effect and mechanism of action of melatonin on activated mast cells. RBL-2H3 were pre-treated with exogenous melatonin (MELx) at physiological (100nM) and pharmacological (1 mM) doses for 30 min, washed and activated with PMACI (phorbol 12-myristate 13-acetate plus calcium ionophore A23187) for 2 h and 12 h. The data shows that pre-treatment of MELx in stimulated mast cells, significantly reduced the levels of endogenous melatonin production (MELn), TNF-α and IL-6. These effects are directly related with the MELx concentration used. MELx also inhibited IKK/NF-κB signal transduction pathway in stimulated mast cells. These results indicate a molecular basis for the ability of melatonin to prevent inflammation and for the treatment of allergic inflammatory diseases through the down-regulation of mast cell activation. J. Cell. Biochem. 117: 1926-1933, 2016. © 2016 Wiley Periodicals, Inc.

Sympathetic nervous system and chronic bladder pain: a new tune for an old song

Chronic bladder pain (CBP) patients present with pelvic pain or discomfort during bladder filling, for at least a period of 6 months, which may be accompanied by lower urinary tract symptoms such as frequency, nocturia, and urgency. However, both the etiology of CBP and pathophysiological mechanisms are not well described. A number of clinical and basic animal model findings support involvement of sympathetic nervous system in chronic pain syndromes such as CBP. Examples include sympathetic overactivity and high plasma or urinary catecholamine levels that have a high correlation with nociceptive symptoms. In this review, we explored the current evidence in support of the involvement of sympathetic overactivity in CBP. As bladder inflammation often occurs among subgroups of CBP patients, we discuss the possible role of sympathetic nervous system in mastocytosis as well examples examples of animal models that further support the involvement of sympathetic dysfunction in CBP. As there is substantive evidence for cross-organ sensitization in the pelvis can lead to co-morbidity of genitourinary and gastrointestinal dysfunctions, we also include how sympathetic dysfunction may play a role in a number of co-morbid chronic pain syndromes.

Acute stress regulates nociception and inflammatory response induced by bee venom in rats: possible mechanisms

Restraint stress modulates pain and inflammation. The present study was designed to evaluate the effect of acute restraint stress on inflammatory pain induced by subcutaneous injection of bee venom (BV). First, we investigated the effect of 1 h restraint on the spontaneous paw-flinching reflex (SPFR), decrease in paw withdrawal mechanical threshold (PWMT) and increase in paw volume (PV) of the injected paw induced by BV. SPFR was measured immediately after BV injection, and PWMT and PV were measured 2 h before BV and 2-8 h after BV. The results showed that acute restraint inhibited significantly the SPFR but failed to affect mechanical hyperalgesia. In contrast, stress enhanced significantly inflammatory swelling of the injected paw. In a second series of experiments, the effects of pretreatment with capsaicin locally applied to the sciatic nerve, systemic 6-hydroxydopamine (6-OHDA), and systemic naloxone were examined on the antinociception and proinflammation produced by acute restraint stress. Local capsaicin pretreatment inhibited BV-induced nociception and inflammatory edema, and had additive effects with stress on nociception but reduced stress enhancement of edema. Systemic 6-OHDA treatment attenuated the proinflammatory effect of stress, but did not affect the antinociceptive effect. Systemic naloxone pretreatment eliminated the antinociceptive effect of stress, but did not affect proinflammation. Taken together, our data indicate that acute restraint stress contributes to antinociception via activating an endogenous opioid system, while sympathetic postganglionic fibers may contribute to enhanced inflammation in the BV pain model.

The role of melatonin in the cells of the innate immunity: a review

Melatonin is the major secretory product synthesized and secreted by the pineal gland and shows both a wide distribution within phylogenetically distant organisms from bacteria to humans and a great functional versatility. In recent years, a considerable amount of experimental evidence has accumulated showing a relationship between the nervous, endocrine, and immune systems. The molecular basis of the communication between these systems is the use of a common chemical language. In this framework, currently melatonin is considered one of the members of the neuroendocrine-immunological network. A number of in vivo and in vitro studies have documented that melatonin plays a fundamental role in neuroimmunomodulation. Based on the information published, it is clear that the majority of the present data in the literature relate to lymphocytes; thus, they have been rather thoroughly investigated, and several reviews have been published related to the mechanisms of action and the effects of melatonin on lymphocytes. However, few studies concerning the effects of melatonin on cells belonging to the innate immunity have been reported. Innate immunity provides the early line of defense against microbes and consists of both cellular and biochemical mechanisms. In this review, we have focused on the role of melatonin in the innate immunity. More specifically, we summarize the effects and action mechanisms of melatonin in the different cells that belong to or participate in the innate immunity, such as monocytes-macrophages, dendritic cells, neutrophils, eosinophils, basophils, mast cells, and natural killer cells.

The leukotriene d4 receptor antagonist, montelukast, inhibits mast cell degranulation in the dermis induced by water avoidance stress

Cysteinyl leukotrienes play a part in inflammatory reactions such as asthma and inflammatory bowel diseases. The leukotrienes exert their actions by binding to and activating various receptors. Montelukast, a leukotriene receptor antagonist, which is used in the treatment of asthma has been shown to be effective in inhibiting the action or formation of leukotrienes. Many skin disorders, such as atopic dermatitis and psoriasis, worsen during stress and seem to be related to infiltration and activation of mast cells that are releasing vasoactive and pro-inflammatory mediators. The aim of the present study was to investigate the effects of montelukast on the degranulation of mast cells in the dermis that is induced by water avoidance stress (WAS). Wistar albino rats were divided into four groups of 8 animals each. Control rats were injected with (1) the vehicle solution or (2) the montelukast solution in the absence of WAS. (3) the WAS group of rats was administered vehicle solution following WAS exposure for 2h daily for 5 days. (4) The WAS+ML group was administered montelukast 10mg/kg; i.p. following WAS exposure for 2h daily for 5 days. Dermal mast cell numbers were determined with toluidine blue and tryptase immunohistochemistry and observed using a light microscope. Numbers of both granulated and degranulated mast cells were significantly increased in the WAS group when compared to control rats. Montelukast treatment decreased the number of both mature granulated and degranulated mast cells in rats subjected to WAS. In conclusion, chronic montelukast treatment reduced WAS-induced infiltration and activation of mast cells in the dermis and may provide a useful therapeutic option in stress-induced skin disorders.

Neuroendocrine and circadian aspects (melatonin and beta-endorphin) of atopic dermatitis in the child

Atopic dermatitis (AD) is a disease of increasing incidence among paediatric patients. Among the factors involved in its pathogenesis is the alteration of the immune response, and so the objective of this study was to evaluate the involvement of certain neuroendocrine factors with immune properties in the development of the disease. Fifty-five subjects were selected and divided into the following three groups: healthy subjects, those diagnosed with symptomatic AD and those with asymptomatic AD. Plasma levels of melatonin and beta-endorphins were measured by radioimmunoassay, in serum samples obtained at 9 am and 9 pm, with two samples being obtained from each of the patients and controls. In the phases of AD outbreaks, there is a reduction in the serum levels of both melatonin and beta-endorphin. In the case of melatonin, the difference is statistically significant only during the day, although nocturnal levels are greater for both hormones. In AD, a central neuroendocrine dysfunction may be a primary pathogenic event. Our hypothesis is that the physiological nocturnal peak of melatonin due to pineal gland production may mask the decline of melatonin of possibly extrapineal (immunological) origin during episodes of dermatitis outbreaks. Further studies are required, particularly of neurovegetative and hormonal aspects, to better define this process. Such a definition would also be of therapeutic interest.

Laughter elevates the levels of breast-milk melatonin

OBJECTIVE

Patients with atopic eczema (AE) often complain of sleep disturbance. Melatonin is involved in sleep, and the levels of blood melatonin in patients with AE are decreased in comparison to healthy subjects. However, the levels of breast-milk melatonin had only been reported in healthy subjects. Laughter increased natural killer cell activity in blood and free radical-scavenging capacity in saliva in healthy subjects. Thus, the effect of laughter on the levels of breast-milk melatonin was studied in mothers with AE. Moreover, the effect of feeding with breast milk after laughter on allergic responses in infants was studied.

METHODS

Forty-eight infants aged 5-6 months were enrolled. All of the infants had AE and were allergic to latex and house dust mite (HDM). Half (n=24) of the mothers of these infants were patients with AE, while another 24 mothers were healthy subjects. The mothers viewed either an 87-min humorous DVD (Modern Times, featuring Charlie Chaplin) or an 87-min nonhumorous weather information DVD at 2000 h. After viewing, breast milk was collected sequentially from 2200, 2400, 0200, 0400 to 0600 h. The levels of breast-milk melatonin were measured. In addition, skin wheal responses to HDM and histamine were studied in infants.

RESULTS

Laughter caused by viewing a humorous DVD increased the levels of breast-milk melatonin in both mothers with AE and healthy mothers. In addition, allergic responses to latex and HDM of infants were reduced by feeding with breast milk after laughter of mothers with AE or of healthy mothers.

CONCLUSION

Laughter increased the levels of breast-milk melatonin in both mothers with AE and healthy mothers, and feeding infants with increased levels of melatonin-containing milk reduced allergic responses in infants. Thus, laughter of mothers may be helpful in the treatment of infants with AE.