Vital role of the itch-scratch response in development of spontaneous dermatitis in NC/Nga mice

Pathophysiological Role of TLR4 in Chronic Relapsing Itch Induced by Subcutaneous Capsaicin Injection in Neonatal Rats

Despite the high prevalence of chronic dermatitis and the accompanied intractable itch, therapeutics that specifically target itching have low efficacy. Increasing evidence suggests that TLRs contribute to immune activation and neural sensitization; however, their roles in chronic itch remain elusive. Here, we show that the RBL-2H3 mast cell line expresses TLR4 and that treatment with a TLR4 antagonist opposes the LPS dependent increase in mRNA levels of Th2 and innate cytokines. The pathological role of TLR4 activation in itching was studied in neonate rats that developed chronic itch due to neuronal damage after receiving subcutaneous capsaicin injections. Treatment with a TLR4 antagonist protected these rats with chronic itch against scratching behavior and chronic dermatitis. TLR4 antagonist treatment also restored the density of cutaneous nerve fibers and inhibited the histopathological changes that are associated with mast cell activation after capsaicin injection. Additionally, the expression of IL-1β, IL-4, IL-5, IL-10, and IL-13 mRNA in the lesional skin decreased after TLR4 antagonist treatment. Based on these data, we propose that inhibiting TLR4 alleviated itch in a rat model of chronic relapsing itch, and the reduction in the itch was associated with TLR4 signaling in mast cells and nerve fibers.

Evaluation of chamomile oil and nanoemulgels as a promising treatment option for atopic dermatitis induced in rats

Background: Atopic dermatitis is a chronic inflammatory skin disease that remarkably affects the quality-of-life of patients. Chamomile oil is used to treat skin inflammations. We evaluated the efficacy of chamomile oil and nanoemulgel formulations as a natural alternative therapeutic option for atopic dermatitis.Research design and methods: Formulations were developed comprising chamomile oil: olive oil (1:1), Tween 20/80 or Gelucire 44/14 as surfactant-cosurfactant mixtures, propylene glycol (10%w/w), water and hydroxypropyl methylcellulose (3%w/w). In-vitro physicochemical characterization, stability testing and in-vivo assessment of inflammatory biomarkers and histopathological examination of skin lesions were conducted in rats induced with atopic dermatitis.Results: Nanoemulgels G₁ and X₁ which displayed the smallest particle size of 137.5 ± 2.04 and 207.1 ± 5.44 nm, good homogeneity and high zeta-potential values of -26.4 and -32.7 mV were selected as the optimized emulgel. Nanoemulgels were nonirritating of pH value 5.56, readily spreadable, and were physically stable following 10 heating-cooling cycles. Treatment with nanoemulgels showed a two-fold decrease in duration of skin healing and no spongiosis compared to chamomile oil. Levels of biomarkers were reduced after topical application of both nanoemulgels and chamomile oil.Conclusion: Nanoemulgels are a potential cost effective, safe topical carrier system for chamomile in treating atopic dermatitis.

Atopic Dermatitis Is a Barrier Issue, Not an Allergy Issue

Atopic dermatitis (AD) is a chronic, relapsing disease that typically manifests in childhood and improves with age. Studies have demonstrated that the presence of AD increases the risk of developing food allergy, allergic rhinitis, and asthma later in life. Although children with AD are more likely to produce allergen-specific immunoglobulin E, there is conflicting evidence that allergen avoidance improves disease severity. Furthermore, food-elimination diets in patients with AD may increase the risk of developing immediate, life-threatening reactions to the removed food. The most effective treatments of AD aim to repair and protect the skin barrier and decrease inflammation.

Tryptophan nitration of immunoglobulin light chain as a new possible biomarker for atopic dermatitis

To reduce the incidence and severity of atopic dermatitis, detection and treatment at an early stage are urgently required, but no effective biomarker has been reported. In this study, we attempted to detect a candidate biomarker of early stage atopic dermatitis by focusing on the levels of nitrated residues in the plasma proteins of atopic dermatitis model mice (NC/Nga mice). We found that the immunoglobulin (Ig) light chain was more highly nitrated in the plasma of the animal model than that of control mice. Western blot analysis showed a statistically significant difference between the 6-nitrotryptophan content of the Ig light chain in the NC/Nga mice before onset of atopic dermatitis symptoms and that of the control mice. LC-ESI-MS/MS analysis demonstrated that these light chains contained nitrotryptophan (Trp56) and nitrotyrosine (Tyr66). Immunofluorescence staining revealed a significant increase in manganese superoxide dismutase and inducible nitric oxide synthase production in the skin lesions of the NC/Nga mice. Furthermore, we found protein-bound 6-nitrotryptophan and 3-nitrotyrosine only in the lesioned skin, where their signals partially overlapped with the IgG signal. Our findings suggest that the 6-nitrotryptophan content of Ig light chains could be a new biomarker for detecting early stage atopic dermatitis.

Exposure-based cognitive behavior therapy for atopic dermatitis: an open trial

Atopic dermatitis (AD) is a common and debilitating inflammatory dermatological disorder and is marked by itch and inflamed skin. Scratching, sleep loss, and avoidance of situations associated with more AD symptoms are central hypothesized mechanisms that perpetuate the disorder and cause reduced quality of life. We developed an exposure-based cognitive behavioral treatment (CBT) that entailed mindfulness practice as a means to increase tolerance for aversive experiences during exposure. The aim of the present study was to test the treatment's acceptability and preliminary efficacy in adults with AD. We used an uncontrolled pretest-posttest design and recruited participants (N = 9) from a university hospital dermatological clinic. The treatment comprised 10 weekly sessions over 10 weeks and assessments of AD symptoms as well as psychiatric symptoms and quality of life were conducted at baseline, posttreatment and 6-month follow-up. The results showed significant and large baseline to posttreatment improvements on self-reported measures of AD symptoms (p = .020) and general anxiety (p = .005), but there was no significant improvement in depression or quality of life. Treatment satisfaction was high and a majority of participants (67%) completed the treatment. We conclude that exposure-based CBT for adult AD can be feasible, acceptable, and potentially efficacious.

Acidosis counteracts itch tachyphylaxis to consecutive pruritogen exposure dependent on acid-sensing ion channel 3

Tachyphylaxis of itch refers to a markedly reduced scratching response to consecutive exposures of a pruritogen, a process thought to protect against tissue damage by incessant scratching and to become disrupted in chronic itch. Here, we report that a strong stimulation of the Mas-related G-protein-coupled receptor C11 by its agonist, Ser-Leu-Ile-Gly-Arg-Leu-NH₂ (SL-NH₂) or bovine adrenal medulla 8-22 peptide, via subcutaneous injection in mice induces tachyphylaxis to the subsequent application of SL-NH₂ to the same site. Notably, co-application of acid and SL-NH₂ following the initial injection of the pruritogen alone counteracted itch tachyphylaxis by augmenting the scratching behaviors in wild-type but not in acid-sensing ion channel 3-null, animals. Using an activity-dependent silencing strategy, we identified that acid-sensing ion channel 3-mediated itch enhancement mainly occurred via the Mas-related G-protein-coupled receptor C11-responsive sensory neurons. Together, our results indicate that acid-sensing ion channel 3, activated by concomitant acid and certain pruritogens, constitute a novel signaling pathway that counteracts itch tachyphylaxis to successive pruritogenic stimulation, which likely contributes to chronic itch associated with tissue acidosis.

Bone adaptation to mechanical loading in a mouse model of reduced peripheral sensory nerve function

Underlying mechanisms contributing to the imbalance in bone turnover during osteoporosis remain only partially explained. Reduced sensory nerve function may contribute to this imbalance, as sensory neuropeptides affect the activity of osteoblasts and osteoclasts in vivo, especially during bone adaptation. In this study, we investigated bone adaptation in mice following two weeks of tibial compression (peak magnitude 3 N or 7 N). To induce decreased sensory nerve function, mice were treated with capsaicin as neonates. We hypothesized that decreased sensory nerve function would diminish the adaptation of bone to mechanical loading, assessed with μCT and dynamic histomorphometry. We found that tibial compression induced significant changes in cortical microarchitecture that depended on compression magnitude and location along the length of the tibia; in contrast, there was no effect of loading on trabecular bone of the tibial metaphysis. Tibial compression significantly increased periosteal, and decreased endosteal, bone formation. Contrary to our initial hypothesis, capsaicin-treated mice generally displayed a similar, if not larger, adaptive response to mechanical loading, including greater increases in bone mineral content and mineral apposition rate. To integrate mechanical loading of bone with sensory nerve activation, we examined whether concentration of the neuropeptides calcitonin gene-related peptide (CGRP) and substance P (SP) in bone were affected following 1 or 5 days of 5 N tibial compression or hindlimb unloading. We found that 1 day of tibial compression significantly increased CGRP concentrations in bone, and hindlimb unloading also exhibited a trend toward increased CGRP in bone. These results may suggest a role of sensory nerves in the bone adaptation response to the mechanical environment, though this remains unclear.

Asthma-like airway inflammation and responses in a rat model of atopic dermatitis induced by neonatal capsaicin treatment

Recent studies have shown that approximately 70% of patients with severe atopic dermatitis (AD) develop asthma. Development of AD in infancy and subsequent other atopic diseases such as asthma in childhood is referred to as atopic march. However, a causal link between the diseases of atopic march has remained largely unaddressed, possibly due to lack of a proper animal model. Recently, we developed an AD rat model showing chronically relapsing dermatitis and scratching behaviors induced by neonatal capsaicin treatment. Here, we investigated whether our model also showed asthmatic changes, with the aim of expanding our AD model into an atopic march model. First, we confirmed that capsaicin treatment (50 mg/kg within 24 h after birth) induced dermatitis and scratching behaviors until 6 weeks of age. After that, the mRNA expression of Th1 and Th2 cytokines, such as IFN-γ and TNF-α, and IL-4, IL-5, and IL-13, respectively, was quantified with quantitative real-time polymerase chain reaction in the skin and the lungs. The number of total cells and eosinophils was counted in bronchoalveolar lavage (BAL) fluid. The levels of IgE in the serum and BAL fluid were determined with enzyme-linked immunosorbent assay. Paraffin-embedded sections (4 μm) were stained with hematoxylin/eosin to analyze the morphology of the lung and the airway. Airway responsiveness was measured in terms of airway resistance and compliance using the flexiVent system. In the capsaicin-treated rats, persistent dermatitis developed, and scratching behaviors increased over several weeks. The levels of IgE in the serum and BAL fluid as well as the mRNA expression of Th2 cytokines, including IL-4, IL-5, and IL-13, in both the skin and the lungs were elevated, and the number of eosinophils in the BAL fluid was also increased in the capsaicin-treated rats compared to control rats. Morphological analysis of the airway revealed smooth muscle hypertrophy and extensive mucus plug in the capsaicin-treated rats. Functional studies demonstrated an increment of the airway resistance and a decrement of lung compliance in the capsaicin-treated rats compared to control rats. Taken together, our findings suggested that neonatal capsaicin treatment induced asthma-like airway inflammation and responses in juvenile rats.

Formaldehyde-Induced Aggravation of Pruritus and Dermatitis Is Associated with the Elevated Expression of Th1 Cytokines in a Rat Model of Atopic Dermatitis

Atopic dermatitis is a complex disease of heterogeneous pathogenesis, in particular, genetic predisposition, environmental triggers, and their interactions. Indoor air pollution, increasing with urbanization, plays a role as environmental risk factor in the development of AD. However, we still lack a detailed picture of the role of air pollution in the development of the disease. Here, we examined the effect of formaldehyde (FA) exposure on the manifestation of atopic dermatitis and the underlying molecular mechanism in naive rats and in a rat model of atopic dermatitis (AD) produced by neonatal capsaicin treatment. The AD and naive rats were exposed to 0.8 ppm FA, 1.2 ppm FA, or fresh air (Air) for 6 weeks (2 hours/day and 5 days/week). So, six groups, namely the 1.2 FA-AD, 0.8 FA-AD, Air-AD, 1.2 FA-naive, 0.8 FA-naive and Air-naive groups, were established. Pruritus and dermatitis, two major symptoms of atopic dermatitis, were evaluated every week for 6 weeks. After that, samples of the blood, the skin and the thymus were collected from the 1.2 FA-AD, the Air-AD, the 1.2 FA-naive and the Air-naive groups. Serum IgE levels were quantified with ELISA, and mRNA expression levels of inflammatory cytokines from extracts of the skin and the thymus were calculated with qRT-PCR. The dermatitis and pruritus significantly worsened in 1.2 FA-AD group, but not in 0.8 FA-AD, compared to the Air-AD animals, whereas FA didn't induce any symptoms in naive rats. Consistently, the levels of serum IgE were significantly higher in 1.2 FA-AD than in air-AD, however, there was no significant difference following FA exposure in naive animals. In the skin, mRNA expression levels of Th1 cytokines such as TNF-α and IL-1β were significantly higher in the 1.2 FA-AD rats compared to the air-AD rats, whereas mRNA expression levels of Th2 cytokines (IL-4, IL-5, IL-13), IL-17A and TSLP were significantly higher in 1.2 FA-naive group than in the Air-naive group. These results suggested that 1.2 ppm of FA penetrated the injured skin barrier, and exacerbated Th1 responses and serum IgE level in the AD rats so that dermatitis and pruritus were aggravated, while the elevated expression of Th2 cytokines by 1.2 ppm of FA in naive rats was probably insufficient for clinical manifestation. In conclusion, in a rat model of atopic dermatitis, exposure to 1.2 ppm of FA aggravated pruritus and skin inflammation, which was associated with the elevated expression of Th1 cytokines.

Solanum tuberosum L. cv Hongyoung extract inhibits 2,4‑dinitrochlorobenzene‑induced atopic dermatitis in NC/Nga mice

Solanum tuberosum L. cv Hongyoung (SH) is a widely consumed anthocyanin-rich food and medicinal plant, which possesses anti-inflammatory and anti-allergic activities. The present study aimed to examine the inhibitory effects of SH extract on atopic dermatitis (AD)-like skin lesions induced by the topical application of 2,4-dinitrochlorobenzene (DNCB) in NC/Nga mice. SH extract was orally administered to the DNCB-treated NC/Nga mice. The anti-AD effects of SH extract were examined by measuring symptom severity; ear thickness; scratching behavior; serum levels of immunoglobulin (Ig)E; T-helper (Th)1, Th2 and Th17 cytokine levels in the spleen; mRNA expression levels of inflammatory cytokines and chemokines; and tissue infiltration of inflammatory cells. The results demonstrated that SH extract inhibited the development of AD-like lesions, and reduced IgE levels and the production of cytokines. Furthermore, SH extract significantly suppressed the expression of AD-associated mRNAs in lesional skin. Histological alterations in the AD-like lesions were visualized using hematoxylin and eosin, and toluidine blue staining in the DNCB-treated group; the alterations were attenuated following SH treatment. In addition, thickening of the epidermis and accumulation of inflammatory cells in the DNCB-treated mice were suppressed by SH treatment. These results suggested that SH extract may suppress the development of AD symptoms through modulation of the Th1 and Th2 responses.

Effect of a 308-nm excimer laser on atopic dermatitis-like skin lesions in NC/Nga mice

BACKGROUND AND OBJECTIVE

Atopic dermatitis (AD) is a common inflammatory skin disease that can affect all age groups. It has a relapsing course, which dramatically affects the quality of life of patients. A 308-nm excimer laser has been reported to be a safe and effective treatment for inflammatory skin diseases, although the range of potential application has not been fully explored. The purpose of this study was to evaluate the therapeutic effects of a 308-nm laser on AD-like skin lesions in NC/Nga mice.

STUDY DESIGN/MATERIALS AND METHODS

Dermatophagoides farinae-exposed NC/Nga mice with a clinical score of 12 were treated with either a 308-nm excimer laser or narrowband-UVB (NB-UVB). The effects of the 308-nm excimer laser were evaluated by dermatitis scores, skin histology, skin barrier function, and immunological parameters, including IgE and Th2-mediated cytokines.

RESULTS

The 308-nm excimer laser significantly reduced the severity of skin lesions and decreased the total serum levels of IgE and Th2-mediated cytokines. The excimer laser also significantly reduced the inflammatory cellular infiltrate into AD-induced skin lesions. Moreover, treatment with the 308-nm excimer laser led to recovery of skin barrier function in AD-induced skin lesions.

CONCLUSION

The 308-nm excimer laser can be considered a valid and safe therapeutic option for the treatment of localized AD. Lasers Surg. Med. 48:629-637, 2016. © 2016 Wiley Periodicals, Inc.

Juvenile obesity aggravates disease severity in a rat model of atopic dermatitis

PURPOSE

There is increasing epidemiological evidence of an association between childhood obesity and atopic dermatitis, but little is known about the underlying mechanism(s). In the present study, we used a rat model of atopic dermatitis to assess whether juvenile obesity, induced by reduction of litter size, aggravated the signs of atopic dermatitis and, if so, whether this aggravation was associated with changes in plasma concentration of adipokines, such as leptin and adiponectin.

METHODS

Dermatitis was induced by neonatal capsaicin treatment. Body weight, dermatitis score, serum IgE, skin nerve growth factor (NGF), serum leptin and adiponectin, and cytokine mRNA expression in the skin lesion were compared between small (SL, 5 pups) and large litters (LL, 15 pups).

RESULTS

The body weight of juvenile rats up to 6 weeks of age was significantly heavier in the SL group, compared with those in the LL group. The SL group showed more robust development of dermatitis, and higher levels of serum IgE and skin NGF than the LL group. Additionally, the SL group demonstrated higher levels of leptin and pro-inflammatory cytokine mRNA but lower levels of adiponectin than the LL group.

CONCLUSIONS

These results suggest a causal link between a decrease in immunological tolerance, induced by juvenile obesity, and aggravation of atopic dermatitis.

Importance of tryptophan nitration of carbonic anhydrase III for the morbidity of atopic dermatitis

The nitration of proteins results from the vigorous production of reactive nitrogen species in inflammatory disease. We previously reported the proteomic analysis of nitrated tryptophan residues in in vitro model cells for inflammatory diseases using a 6-nitrotryptophan-specific antibody. In this paper, we applied this method to the analysis of a disease model animal and identified the 6-nitrotryptophan-containing proteins in the skin of atopic dermatitis model mice (AD-NC/Nga mice). We found three nitrotryptophan-containing proteins, namely, carbonic anhydrase III (CAIII), α-enolase (α-ENO), and cytoskeletal keratin type II (KTII), and identified the positions of the nitrotryptophan residues in their amino acid sequences: Trp47 and Trp123 in CAIII, Trp365 in α-ENO, and Trp221 in KTII. Among these, the nitration of CAIII was increased not only in the lesional skin of AD-NC/Nga mice but also in the mice that did not present any symptoms. The in vitro nitration of purified CAIII by peroxynitrite reduced its CO2 hydratase activity in a dose-dependent manner. In addition, we found that CAIII was induced during the differentiation of normal human epidermal keratinocytes. Furthermore, we found the presence of CAIII and the formation of 6-nitrotryptophan-containing proteins in both the lesional and the nonlesional sections of the skin of patients with atopic dermatitis through immunohistochemical staining. This study provides the first demonstration of the formation of 6-nitrotryptophan in human tissues and disease.

Low-dose ethanol aggravates allergic dermatitis in mice

Alcohol injures dendritic cells and suppresses cellular immunity, while some evidence indicates that drinking alcohol aggravates allergic asthma. This study investigated the effect of low doses of ethanol in enhancing allergic reactions in the skin of mice. Liquid food containing alcohol was administered to conventional NC/Nga mice to induce alcoholic hepatic steatosis, and spontaneous dermatitis was evaluated. BALB/c mice were administered approximately 1 g/kg body weight of ethanol by gavage, and contact hypersensitivity (CHS) or active cutaneous anaphylaxis (ACA) was induced. Spleens were collected 24 h after the elicitation of CHS and mRNA expressions of interferon (IFN)-γ, interleukin (IL)-4, IL-6, IL-10, and IL-18 were measured by quantitative RT-PCR. Alcohol-containing diet exaggerated spontaneous dermatitis in conventional NC/Nga mice and contact hypersensitivity in BALB/c mice. Ethanol administered by gavage for 5 days enhanced contact hypersensitivity in BALB/c mice. Ethanol administration with gavage also enhanced ACA of BALB/c mice. Ethanol did not affect mRNA expression of IFN-γ and IL-4, but did enhance IL-6, IL-10, and IL-18 mRNA expression. Histological evaluation revealed an absence of hepatic steatosis in mice administered ethanol by gavage for 5 days. In ethanol-administered mice, inflamed areas presented as lesions or a local extreme accumulation of mononuclear cells in the epidermis. These findings suggest that ethanol enhances the expression of inflammatory cytokines independently from T helper (Th)1/Th2 cytokine phenotypes, causing abnormalities in the epidermis resulting in exacerbated allergic reactivity.

Juvenile obesity aggravates disease severity in a rat model of atopic dermatitis

Purpose

There is increasing epidemiological evidence of an association between childhood obesity and atopic dermatitis, but little is known about the underlying mechanism(s). In the present study, we used a rat model of atopic dermatitis to assess whether juvenile obesity, induced by reduction of litter size, aggravated the signs of atopic dermatitis and, if so, whether this aggravation was associated with changes in plasma concentration of adipokines, such as leptin and adiponectin.

Methods

Dermatitis was induced by neonatal capsaicin treatment. Body weight, dermatitis score, serum IgE, skin nerve growth factor (NGF), serum leptin and adiponectin, and cytokine mRNA expression in the skin lesion were compared between small (SL, 5 pups) and large litters (LL, 15 pups).

Results

The body weight of juvenile rats up to 6 weeks of age was significantly heavier in the SL group, compared with those in the LL group. The SL group showed more robust development of dermatitis, and higher levels of serum IgE and skin NGF than the LL group. Additionally, the SL group demonstrated higher levels of leptin and pro-inflammatory cytokine mRNA but lower levels of adiponectin than the LL group.

Conclusions

These results suggest a causal link between a decrease in immunological tolerance, induced by juvenile obesity, and aggravation of atopic dermatitis.

Inhibitory effects of Solanum tuberosum L. var. vitelotte extract on 2,4-dinitrochlorobenzene-induced atopic dermatitis in mice

OBJECTIVES

We aimed to investigate the inhibitory efficacy of Solanum tuberosum L. var. Vitelotte (SV) extract on atopic dermatitis (AD)-like skin lesions induced by the topical application of 2,4-dinitrochlorobenzene in NC/Nga mice.

METHODS

SV extract was administered orally to NC/Nga mice at the dose of 75, 150 or 300 mg/kg for 4 weeks. The effectiveness of SV extract in NC/Nga mice was evaluated by measuring symptom severity, ear thickness, scratching behaviour, serum levels of IgE, IgG1 and IgG2a, T helper 1 (Th1; interferon-γ and IL-12) and Th2 cytokines (IL-4 and IL-13) in spleen, messenger RNA (mRNA) expression of inflammatory cytokines and chemokines in tissue and infiltration of inflammatory cells in tissue.

KEY FINDINGS

Oral administration of SV extract to NC/Nga mice resulted in the inhibition of the development of AD-like skin lesions. SV extract was attenuated AD-like skin lesion, ear thickening and scratching behaviour. SV extract also alleviated infiltrated inflammatory cells in tissue. Production of Th1 and Th2 cytokines was inhibited in splenocyte cultures. Additionally, reduced levels of IgE and IgG1/IgG2a ratio in serum and expression of AD-related mRNAs in lesional skins were observed in SV-treated mice compared with control group.

CONCLUSIONS

SV extract alleviated the exacerbation of AD-like skin lesions in NC/Nga mice by suppressing total serum level of IgE and correcting the Th1/Th2 balance.

The ion channel TRPA1 is required for chronic itch

Chronic itch is a debilitating condition that affects one in 10 people. Little is known about the molecules that mediate chronic itch in primary sensory neurons and skin. We demonstrate that the ion channel TRPA1 is required for chronic itch. Using a mouse model of chronic itch, we show that scratching evoked by impaired skin barrier is abolished in TRPA1-deficient animals. This model recapitulates many of the pathophysiological hallmarks of chronic itch that are observed in prevalent human diseases such as atopic dermatitis and psoriasis, including robust scratching, extensive epidermal hyperplasia, and dramatic changes in gene expression in sensory neurons and skin. Remarkably, TRPA1 is required for both transduction of chronic itch signals to the CNS and for the dramatic skin changes triggered by dry-skin-evoked itch and scratching. These data suggest that TRPA1 regulates both itch transduction and pathophysiological changes in the skin that promote chronic itch.

Atopic dermatitis-mitigating effects of new Lactobacillus strain, Lactobacillus sakei probio 65 isolated from Kimchi

AIMS

Atopic dermatitis (AD) is an inflammatory skin disease. Probiotics have been reported to modulate immune responses and thus are now being suggested as potential treatments for allergies. In this study, we investigated the inhibitory effects of Lactobacillus sakei probio 65 isolated from Kimchi on artificially inducing AD in NC/Nga mice.

METHODS AND RESULTS

Oral administration of viable or heat-inactivated Lact. sakei probio 65 improved the condition of skin and reduced scratching frequency. Serum levels of IgE and cutaneous T-cell-attracting chemokine (CTACK) were significantly decreased by this therapy. Dead Lact. sakei probio 65 also decreased IL-4 and IL-6 serum concentrations. Moreover, both live and dead Lact. sakei probio 65 inhibited the expression of Thymus and activation-regulated chemokine and CTACK in AD-like skin lesions. The increased levels of Foxp3 expression in the lesional skin and ears were also suppressed by Lact. sakei probio 65. In addition, Lact. sakei probio 65 inhibited β-hexosaminidase release and the secretion of IL-4, TNF-α and IL-6 from RBL-2H3 cells.

CONCLUSIONS

Oral treatment with both viable and heat-inactivated Lact. sakei probio 65 inhibits skin inflammation and AD-like skin lesions, as well as mast cell activation.

SIGNIFICANCE AND IMPACT OF THE STUDY

Lactobacillus sakei probio 65 has an inhibitory effect on atopic dermatitis-like skin lesions and may represent an effective new anti-inflammatory agent.

Inhibitory effects of polysaccharide-rich extract of Phragmites rhizoma on atopic dermatitis-like skin lesions in NC/Nga mice

AIMS

Phragmites rhizoma was reported to have anti-oxidative and free radical scavenging activity. It also has been traditionally used to suppress inflammation. In the present study, we aimed to evaluate the topical effects of the polysaccharide-rich extract of P. rhizoma (PEP) on atopic dermatitis.

MAIN METHODS

We induced AD-like skin lesions by an extract of the house-dust mite Dermatophagoides farinae (Dfb) in NC/Nga mice, and then performed macroscopic analysis, immunohistochemical staining and measurement of total serum IgE and cytokine production by ELISA.

KEY FINDINGS

Topically applied PEP suppressed dermatitis with a decrease in dermatitis score and scratch number. The histological manifestations of atopic skin lesions including thickened epidermis and increased numbers of mast cells, polymorphonuclear leukocytes and nerve fibers were significantly attenuated. The activation of IgE and the levels of cytokines such as IFN-γ IL-4 and IL-10 were also decreased.

SIGNIFICANCE

Our results indicated that PEP might have an inhibitory effect on atopic dermatitis-like lesion and be a promising natural resource in the treatment of atopic dermatitis.

Stress induced neuroendocrine-immune plasticity: A role for the spleen in peripheral inflammatory disease and inflammaging?

Research over the past decade has revealed close interaction between the nervous and immune systems in regulation of peripheral inflammation linking psychosocial stress with chronic somatic disease and aging. Moreover emerging data suggests that chronic inflammations lead to a pro-inflammatory status underlying premature aging called inflammaging. In this context, the spleen can be seen as a switch board monitoring peripherally derived neuroendocrine-immune mediators in the blood and keeping up a close communication with the central stress response via its mainly sympathetic innervation. The effect aims at balanced and well-timed stress axis activation and immune adaptation in acute peripheral inflammatory events. Constant adjustment to the needs generated by environmental and endogenous challenges is provided by neuroendocrine-immune plasticity. However, maladaptive plasticity induced e.g., by chronic stress-axis activation and excessive non-neuronal derived neuroendocrine mediators may be at the heart of the observed stress sensitivity promote inflammaging under chronic inflammatory conditions. We here review the role of neurotransmitters, neuropeptides and neurotrophins as stress mediators modulating the immune response in the spleen and their potential role in inflammaging.

Omega-3 fatty acid-derived mediator, Resolvin E1, ameliorates 2,4-dinitrofluorobenzene-induced atopic dermatitis in NC/Nga mice

Atopic dermatitis (AD) is a common inflammatory skin disease for which few effective treatments are available. Resolvin E1 (RvE1; 5S,12R,18R-trihydroxy-6Z,8E,10E,14Z,16E-eicosapentaenoic acid) is an endogenous lipid mediator derived from omega-3 fatty eicosapentaenoic acid, which is a potent inhibitor of inflammation. AD-like skin lesion was induced by repetitive skin contact with DNFB in NC/Nga mice and the effects of RvE1 were evaluated on the basis of histopathological findings of skin, ear swelling and cytokine production of CD4(+) T cells. Intraperitoneal injection of RvE1 for one week after DNFB challenge significantly lowered ear swelling and improved back skin lesions. In addition, RvE1 significantly suppressed production of interferon-gamma (IFN-γ) and interleukin-4 (IL-4) by activated CD4(+) T cells and serum IgE level. Furthermore, RvE1 reduced DNFB-induced infiltration of eosinophils, mast cells, CD4(+) T cells, and CD8(+) T cells in skin lesions. Therefore, RvE1 may suppress the development of AD-like skin lesions in DNFB-treated NC/Nga mice by reducing IL-4 and IFN-γ of activated CD4(+) T cells and serum IgE levels and infiltration of immune cells to skin lesion.

Anti pruritic effects of topical crotamiton, capsaicin, and a corticosteroid on pruritogen-induced scratching behavior

Itch accompanies various skin diseases. As a number of mediators other than histamine can be involved in the itch sensation, H1 receptor antagonists are not necessarily effective in treating itch. External application of antipruritic drugs is occasionally used as an alternative therapy for pruritic skin conditions, such as pruritus on primary non-diseased, non-inflamed skin. Even so, the actual effects of these drugs on the itch sensation have yet to be studied in detail. To verify the antipruritic effects of crotamiton, capsaicin, and a corticosteroid on the itch sensation, we examined the inhibitory effects of these drugs on various pruritogen-induced scratching behaviors in mice. Topical application of 10% crotamiton moderately inhibited histamine-, serotonin-, and PAR-2 agonist-induced scratching behaviors. Topical capsaicin (0.025%) also exerted a moderate suppressive effect on histamine-, substance P-, and PAR-2 agonist-induced itch responses. Notably, topical corticosteroid (0.05% clobetasol propionate) remarkably inhibited the scratching behaviors induced by all of the pruritogenic agents tested. Therapeutic effects of capsaicin on substance P-induced pruritus did not seem to be mediated by desensitization of the TRPV1 (+) C fibers and/or by altered responsiveness of the mast cells. In addition, the antipruritic effects of crotamiton and corticosteroid appear to be, at least partly, associated with a TRPV1-independent pathway. This study examined the itch responses to pruritogens and demonstrated the mode of action of the externally applied antipruritic drugs.

Therapeutic potential of Lactobacillus plantarum CJLP133 for house-dust mite-induced dermatitis in NC/Nga mice

Lactobacillus plantarum CJLP133 was isolated from Kimchi, a Korean fermented food, and its potential to improve mouse atopic dermatitis after onset was studied. Dermatitis was developed through house dust-mite extract application onto NC/Nga mice, and then CJLP133 feeding was started. CJLP133 suppressed dermatitis-like skin lesions and decreased high serum IgE levels through balancing between IL-4 and IFN-γ in serum. CJLP133 diminished skin thickening, mast cell accumulation into inflamed site, and lymph node enlargement. In lymph node cells, CJLP133 repressed secretion of T cell cytokines such as IFN-γ, IL-4, IL-5, and IL-10. However, CJLP133 decreased ratios of IFN-γ and IL-5 to IL-10 in lymph node cells, while it did not decrease ratios of IL-4 and IL-5 to IFN-γ. Conclusively, CJLP133 exhibited therapeutic potential for atopic dermatitis in mice through orderly increment of type 1 helper T cell activation and regulatory T cell activation. These results suggest that CJLP133 could treat human atopic dermatitis.

Chronically relapsing pruritic dermatitis in the rats treated as neonate with capsaicin; a potential rat model of human atopic dermatitis

BACKGROUND

The pathophysiological mechanisms underlying chronic pruritic skin diseases, e.g. atopic dermatitis (AD), and effective therapies remain elusive due to the paucity of animal models. Recently, we rediscovered that injection of capsaicin into rat pups resulted in vigorous scratching behavior and chronically relapsing AD-like cutaneous lesions well into adulthood.

OBJECTIVES

To characterize the chronic pruritic dermatitis induced by neonatal capsaicin treatment.

METHODS

Capsaicin (50mg/kg) was given to rat pups subcutaneously within 48 h after birth, and then scratching behavior, dermatitis and pathophysiological changes of rat skin were investigated chronologically.

RESULTS

Neonatal capsaicin treatment led to not only severe scratching and cutaneous lesions but also a large number of pathophysiological changes in the skin, such as histopathological changes including the deficiency of epidermal filaggrin expression, increases in the number of mast cells, levels of tissue NGF and Th2 cytokine mRNA, impaired skin barrier function and colonization with S. aureus. In addition, we observed the hyperproduction of serum IgE, which is clinically similar to the pathophysiology seen in the patients with atopic dermatitis. During the follow-up observation, the rats showed the alternative periods of relapsing and remitting skin lesions.

CONCLUSION

Injection of capsaicin into rat pups results in chronically relapsing pruritic dermatitis, similar to human AD. Therefore, we think neonatal capsaicin treatment could be a useful model for studying human AD and for the development of novel therapeutic drugs.

Rosmarinic acid attenuates 2,4-dinitrofluorobenzene-induced atopic dermatitis in NC/Nga mice

Atopic dermatitis (AD) is one of the most common skin diseases, and its incidence is increasing in industrialized countries. Furthermore, the epicutaneous application of a hapten, such as 2,4-dinitrofluorobenzene (DNFB), evokes an AD-like lesion in NC/Nga mice under specific pathogen-free (SPF) conditions. Rosmarinic acid (RA) is a secondary metabolite that is frequently found in herbs, and has anti-inflammatory, anti-oxidant, and anti-microbial effects. In this study, we studied whether RA is an effective treatment against DNFB-induced AD-like skin lesions in NC/Nga mice. RA at 1 or 5 μM was found to suppress the productions of interferon (IFN)-γ and interleukin (IL)-4 significantly by activated CD4(+) T cells. Furthermore, an intraperitoneal injection of RA at 10 or 50 mg/kg significantly inhibited skin lesion development and ear thickness and total serum IgE level increases in DNFB-treated NC/Nga mice. In addition, intraperitoneal administered RA at 10 or 50 mg/kg significantly inhibited the infiltrations of CD4(+) T, CD8(+) T, and mast cells into DNFB-induced skin lesions in NC/Nga mice. This study suggests that RA suppresses the development of AD-like dermatitis in DNFB-treated NC/Nga mice by reducing IFN-γ and IL-4 production by activated T cells and total serum IgE levels.

Resting but not CpG stimulated keratinocytes suppress autologous T-helper cell proliferation--importance of PGE2 and T regulatory function

In the last decade, keratinocytes have increasingly been recognized to actively participate in the skin immune response. However, their influence on infiltrating lymphocytes - abundantly found in e.g. atopic and psoriatic inflammation - is still controversial. In this study, we aimed to investigate the influence of keratinocytes on T-cell proliferation by use of an autologous co-culture model. Because the skin has an important function with regard to detecting invading pathogens, we also investigated the influence of pathogen-associated molecular pattern on keratinocyte - T-cell interaction. We observed a clear inhibition of T-cell proliferation by co-cultured keratinocytes. This effect was found to be mediated by PGE2, as T-cell proliferation was recovered in the presence of the PGE2 inhibitor indometacin. Furthermore, presence of keratinocytes led to enhanced expression of the T regulatory cell-specific transcription factor Foxp3 in the CD4+CD25+ T-cell population which also showed regulatory function. Interestingly, the presence of the TLR9 ligand CpG was able to prevent the inhibition of T-cell proliferation. This was paralleled by a reduced PGE2 production by keratinocytes and a down-regulated T regulatory cell function. Our results indicate that the inhibitory capacity of keratinocytes in the skin is strongly influenced by the surrounding micromillieu.

Low susceptibility of NC/Nga mice to the lipopolysaccharide-mediated lethality with D-galactosamine sensitization and the involvement of fewer natural killer T cells

The LPS-mediated lethality of NC/Nga mice, having fewer NKT cells, was examined by using d-galactosamine (d-GalN)-sensitization. The NC/Nga mice were not killed by a simultaneous administration of d-GalN and LPS whereas all C57BL/6 (B6) control mice were killed. The injection of d-GalN and LPS failed to elevate the levels of serum alanine aminotransferase and caspase 3 in the liver tissues of NC/Nga mice. Further, the nitric oxide (NO) level of the d-GalN- and LPS-injected NC/Nga mice was much lower than those of the B6 mice. The expression of an inducible NO synthase (iNOS) was significantly reduced in the livers of NC/Nga mice. However, there was no significant difference in LPS-induced TNF-α production between B6 mice and NC/Nga mice. The NC/Nga mice had an impaired expression of IFN-γ protein and mRNA in response to d-GalN and LPS. The pretreatment with α-galactosylceramide (α-GalCer), which activates Vα14(+) NKT cells and induces the production of IFN-γ, rendered NC/Nga mice more susceptible to the LPS-mediated lethality. The livers of NC/Nga mice had fewer NKT cells compared to B6 mice. Taken together, it is suggested that the resistance of NC/Nga mice to the LPS-mediated lethality with d-GalN sensitization depended on the impaired IFN-γ production caused by fewer NKT cells and reduced NO production that followed.

Strong exercise stress exacerbates dermatitis in atopic model mice, NC/Nga mice, while proper exercise reduces it

Atopic dermatitis is well known to exacerbate by stress. How the influence of exercise stress on the skin symptoms in patients with atopic dermatitis has not been clarified. The purpose of our research is to investigate how different strength of exercise stress acts on atopic dermatitis. Specific pathogen-free (SPF) and conventional NC/Nga male mice were used for the experiments. Conventional mice but not SPF group spontaneously develop dermal symptom similar to that of patients with atopic dermatitis at their age of 7 weeks. They were given two types of stress, mild (20 m/min for 60 min) or strong exercise (25 m/min for 90 min), using a treadmill four times per day. The dermal symptom of the conventional group was strongly exacerbated by strong exercise but ameliorated by mild exercise. Under the standard experimental conditions, plasma concentrations of α-melanocyte-stimulating hormone (α-MSH), transforming growth factor-β (TGF-β) and substance P in conventional mice increased markedly with concomitant exacerbation of the symptom. The plasma concentrations of these proteins elevated after strong exercise but decreased after mild exercise. Under the conventional conditions, plasma levels of β-endorphin increased with time by some mechanisms enhanced by the mild exercise. These observations suggested that exercise-induced stress significantly affect the symptom of atopic dermatitis in a pivotal manner depending on the plasma levels of TGF-β, α-MSH, substance P and β-endorphin.

Pathophysiology and therapy of pruritus in allergic and atopic diseases

Pruritus (itch) is a major characteristic and one of the most debilitating symptoms in allergic and atopic diseases and the diagnostic hallmark of atopic dermatitis. Pruritus is regularly defined as an unpleasant sensation provoking the desire to scratch. Although we achieved rather good knowledge about certain inducers of itch such as neuropeptides, amines, mu-opioids, cytokines and proteases, for example, less is known about the pathophysiological specifities among the different diseases, and the therapeutic consequences which may derive thereoff. This review dissects the role of mediators, receptors and itch inhibitors on peripheral nerve endings, dorsal root ganglia, the spinal cord and the CNS leading to the amplification or - vice versa - suppression of pruritus. As the treatment of pruritus in allergic and atopic skin disease is still not satisfactory, knowing these pathways and mechanisms may lead to novel therapeutic approaches against this frequently encountered skin symptom.

Cellular and molecular mechanisms in atopic dermatitis

Atopic dermatitis (AD) is a pruritic inflammatory skin disease associated with a personal or family history of allergy. The prevalence of AD is on the rise and estimated at approximately 17% in the USA. The fundamental lesion in AD is a defective skin barrier that results in dry itchy skin, and is aggravated by mechanical injury inflicted by scratching. This allows entry of antigens via the skin and creates a milieu that shapes the immune response to these antigens. This review discusses recent advances in our understanding of the abnormal skin barrier in AD, namely abnormalities in epidermal structural proteins, such as filaggrin, mutated in approximately 15% of patients with AD, epidermal lipids, and epidermal proteases and protease inhibitors. The review also dissects, based on information from mouse models of AD, the contributions of the innate and adaptive immune system to the pathogenesis of AD, including the effect of mechanical skin injury on the polarization of skin dendritic cells, mediated by keratinocyte-derived cytokines such as thymic stromal lymphopoietin (TSLP), IL-6, and IL-1, that results in a Th2-dominated immune response with a Th17 component in acute AD skin lesions and the progressive conversion to a Th1-dominated response in chronic AD skin lesions. Finally, we discuss the mechanisms of susceptibility of AD skin lesions to microbial infections and the role of microbial products in exacerbating skin inflammation in AD. Based on this information, we discuss current and future therapy of this common disease.

Oral chymase inhibitor SUN13834 ameliorates skin inflammation as well as pruritus in mouse model for atopic dermatitis

Chymase is a chymotrypsin-like serine protease exclusively stored in secretory granules of mast cells and has been thought to participate in allergic diseases. It has already been shown that chymase inhibitor SUN13834 improves dermatitis in NC/Nga mice that spontaneously develop dermatitis resembling atopic dermatitis. In the present study, effect of chymase inhibitor SUN13834 on itch, the major feature of atopic dermatitis, was examined using a mouse dermatitis model induced by repeated topical application of 2,4-dinitrofluorobenzene (DNFB). Oral administration of SUN13834 once a day for 5 weeks inhibited not only skin swelling but accumulation of inflammatory cells including mast cells and eosinophils in the skin of the mice. In addition, SUN13834 also decreased significantly at 10 and 50 mg/kg the amount of scratching behavior induced by the DNFB challenge. This result indicates for the first time that mast cell chymase may be involved in itch induction. In conclusion, SUN13834 is thought to be useful as therapeutic agent for atopic dermatitis.

Effect of Lactobacillus acidophilus strain L-55 on the development of atopic dermatitis-like skin lesions in NC/Nga mice

In this study, we examined whether Lactobacillus acidophilus strain L-55 (strain L-55) suppresses the development of atopic dermatitis (AD)-like skin lesions induced by repeated application of 2,4,6-trinitrochlorobenzene (TNCB) in sensitized NC/Nga mice. The effect of strain L-55 was assessed by measuring clinical symptoms, ear swelling, scratching behavior and serum levels of total IgE. Strain L-55 was administered orally once a day: Strain L-55 at doses of 1 and 10 mg cells/mouse inhibited the development of AD-like skin lesions in dermatitis scores for the back. The increase of dermatitis score and ear swelling was also inhibited by strain L-55. In addition, strain L-55 also caused an inhibition of histological changes induced by repeated application of TNCB. Scratching behavior observed in the back and ear was inhibited by strain L-55. Furthermore elevated serum IgE levels observed by TNCB were also decreased by strain L-55. These results indicate that the inhibition of strain L-55 on AD-like lesions induced by repeated application of TNCB in sensitized NC/Nga mice occurred via a decrease in the serum total IgE level.

Inhibition of atopic dermatitis-like skin lesions by topical application of a novel ceramide derivative, K6PC-9p, in NC/Nga mice

Atopic dermatitis (AD) is a chronic inflammatory skin disease that commonly begins in childhood. K6PC-9p (N-(Ethyl dihydrogenphosphate)-2-hexyl-3-oxo-decanamide) is a synthetic ceramide derivative of PC-9S (N-Ethanol-2-mirystyl-3-oxo-staramide), which was known to be effective in atopic patients. In this study, we examined the effect of topical application of K6PC-9p on skin inflammation and AD-like skin lesions in mouse models. K6PC-9p dose-dependently inhibited phorbol ester-induced increase in ear thickness in BALB/c mice. Moreover, topical application of K6PC-9p suppressed dust mite extract-induced AD-like skin lesions in NC/Nga mice. Histopathological analysis revealed that both ear swelling and leucocyte infiltration were suppressed by K6PC-9p treatment. K6PC-9p also suppressed IL-4 and TNF-alpha expression in the ears and mast cell infiltration into the ears in NC/Nga mice. Further study demonstrated that K6PC-9p inhibited ConA-induced IL-4 secretion and LPS-induced macrophage activation. Taken together, our results showed that topical application of K6PC-9p exerts beneficial effects in animal model of skin inflammation and AD, suggesting that K6PC-9p might be a promising topical agent for the treatment of inflammatory skin diseases.

Inhibitory effects of Saururus chinensis (LOUR.) BAILL on the development of atopic dermatitis-like skin lesions in NC/Nga mice

The present study was performed to examine whether the leaves of Saururus chinensis (LOUR.) BAILL (SC), an herb used for the management of various skin diseases including atopic dermatitis (AD) in Eastern countries, inhibited the development of AD-like skin lesions in NC/Nga mice which was induced by repeated application of picryl chloride (PiCl). The efficacy of SC was judged by measurement of skin severity, itching behavior, histological study, serum IgE levels, IL-4 and IFN-gamma in lymph nodes. Oral administration of SC extract to the PiCl-treated NC/Nga mice for 8 weeks (5 d per week) inhibited significantly the development of AD-like skin lesions macroscopically. Histologically, SC inhibited dermatitis changes like hypertrophy, hyperkeratosis, and infiltration of inflammatory cells into epidermis and dermis. The itching behavior and serum IgE level decreased significantly after SC administration. SC administration enhanced IFN-gamma mRNA expression but did not have an effect on IL-4 mRNA expression. These results suggest that SC could inhibit the development of AD-like skin lesions in NC/Nga mice possibly through modulating the Th1/Th2 imbalance by the promoting of Th1 cell response. Thus, SC may be an alternative substance for the management of AD patients.

TCDD exposure exacerbates atopic dermatitis-related inflammation in NC/Nga mice

Our previous study showed that 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) exposure of NC/Nga mice, a mouse model of atopic dermatitis, induces no dermal changes. In the present study, to investigate whether TCDD exacerbates atopic dermatitis-like skin lesions elicited in NC/Nga mice, NC/Nga mice were applied with picryl chloride (PC), and then were exposed to a single oral dose of 0 (control), 5, and 20 microg TCDD/kg. Two weeks later, spleens, blood, and skin specimens were collected. TCDD exposure increased the production of Th1-type cytokine IFN-gamma, but not Th2-type cytokine IL-4, from spleen cells stimulated with a mitogen. The plasma total IgE antibody levels of the TCDD-exposed mice remained at control levels. On the other hand, TCDD exposure markedly increased the mast cell infiltration and degranulation in PC-sensitized NC/Nga mice histologically, as compared with control mice. These results suggest that TCDD exposure exacerbates atopic dermatitis-related inflammation with no increase of IgE antibody production and that TCDD may be one of the environmental pollutants that induce exacerbations of atopic diseases.