Adipose-derived stem cells decolonize skin Staphylococcus aureus by enhancing phagocytic activity of peripheral blood mononuclear cells in the atopic rats.

Staphylococcus aureus (S. aureus) is known to induce apoptosis of host immune cells and impair phagocytic clearance, thereby being pivotal in the pathogenesis of atopic dermatitis (AD). Adipose-derived stem cells (ASCs) exert therapeutic effects against inflammatory and immune diseases. In the present study, we investigated whether systemic administration of ASCs restores the phagocytic activity of peripheral blood mononuclear cells (PBMCs) and decolonizes cutaneous S. aureus under AD conditions. AD was induced by injecting capsaicin into neonatal rat pups. ASCs were extracted from the subcutaneous adipose tissues of naïve rats and administered to AD rats once a week for a month. Systemic administration of ASCs ameliorated AD-like symptoms, such as dermatitis scores, serum IgE, IFN-γ+/IL-4+ cell ratio, and skin colonization by S. aureus in AD rats. Increased FasL mRNA and annexin V+/7-AAD+ cells in the PBMCs obtained from AD rats were drastically reversed when co-cultured with ASCs. In contrast, both PBMCs and CD163+ cells bearing fluorescent zymosan particles significantly increased in AD rats treated with ASCs. Additionally, the administration of ASCs led to an increase in the mRNA levels of antimicrobial peptides, such as cathelicidin and ß-defensin, in the skin of AD rats. Our results demonstrate that systemic administration of ASCs led to decolonization of S. aureus by attenuating apoptosis of immune cells in addition to restoring phagocytic activity. This contributes to the improvement of skin conditions in AD rats. Therefore, administration of ASCs may be helpful in the treatment of patients with intractable AD.

Oxytocin produces thermal analgesia via vasopressin-1a receptor by modulating TRPV1 and potassium conductance in the dorsal root ganglion neurons.

Recent studies have provided several lines of evidence that peripheral administration of oxytocin induces analgesia in human and rodents. However, the exact underlying mechanism of analgesia still remains elusive. In the present study, we aimed to identify which receptor could mediate the analgesic effect of intraperitoneal injection of oxytocin and its cellular mechanisms in thermal pain behavior. We found that oxytocin-induced analgesia could be reversed by d(CH2)5[Tyr(Me)2,Dab5] AVP, a vasopressin-1a (V1a) receptor antagonist, but not by desGly-NH2-d(CH2)5[DTyr2, Thr4]OVT, an oxytocin receptor antagonist. Single cell RT-PCR analysis revealed that V1a receptor, compared to oxytocin, vasopressin-1b and vasopressin-2 receptors, was more profoundly expressed in dorsal root ganglion (DRG) neurons and the expression of V1a receptor was predominant in transient receptor potential vanilloid 1 (TRPV1)-expressing DRG neurons. Fura-2 based calcium imaging experiments showed that capsaicin-induced calcium transient was significantly inhibited by oxytocin and that such inhibition was reversed by V1a receptor antagonist. Additionally, whole cell patch clamp recording demonstrated that oxytocin significantly increased potassium conductance via V1a receptor in DRG neurons. Taken together, our findings suggest that analgesic effects produced by peripheral administration of oxytocin were attributable to the activation of V1a receptor, resulting in reduction of TRPV1 activity and enhancement of potassium conductance in DRG neurons.

Glyoxal-induced exacerbation of pruritus and dermatitis is associated with staphylococcus aureus colonization in the skin of a rat model of atopic dermatitis.

BACKGROUND: Atopic dermatitis (AD) is a highly pruritic, chronic inflammatory skin disease associated with hyperreactivity to environmental triggers. Among those, outdoor air pollutants such as particulate matter (PM) have been reported to aggravate pre-existing AD. However, underlying mechanisms of air pollution-induced aggravation of AD have hardly been studied. OBJECTIVE: To investigate the molecular mechanisms by which glyoxal, a PM-forming organic compound, exacerbates the symptoms of AD induced by neonatal capsaicin treatment. METHODS: Naïve and AD rats had been exposed to either fresh air or vaporized glyoxal for 5 weeks (2 h/day and 5 days/week) since one week of age. Pruritus and dermatitis were measured every week. The skin and blood were collected and immunological traits such as Staphylococcus aureus skin colonization, production of antimicrobial peptides and immunoglobulin, and mRNA expression of inflammatory cytokines were analyzed. RESULTS: Exposure to glyoxal aggravated pruritus and dermatitis in AD rats, but did not induce any symptoms in naïve rats. Staphylococcus aureus skin colonization was increased in the skin of both naïve and AD rats. Expression of antimicrobial peptides such as LL-37 and ß-defensin-2 was also increased by exposure to glyoxal in the skin of both naïve and AD rats. The mRNA expression of Th1-related cytokines was elevated on exposure to glyoxal. However, serum immunoglobulin production was not significantly changed by exposure to glyoxal. CONCLUSION: In AD rats, exposure to glyoxal exacerbated pruritus and cutaneous inflammation, which was associated with increased colonization of S. aureus and subsequent immunological alterations in the skin.

Effects of Exposure of Formaldehyde to a Rat Model of Atopic Dermatitis Induced by Neonatal Capsaicin Treatment.

Atopic dermatitis is chronically relapsing pruritic eczema and prevails around the world especially in developed countries. Complex interactions between genetic and environmental factors are known to play an important role in the pathophysiology of atopic dermatitis. However, we still lack a detailed picture of the pathogenesis of this disease. Thus, it is of importance to develop appropriate animal models for elucidating the progression of atopic dermatitis. Moreover, investigating the effect of environmental factors such as air pollutants on atopic dermatitis expands understanding of the disease. Here, we describe a method for inducing atopic dermatitis in rats with neonatal capsaicin treatment and a protocol for exposure of a constant concentration of formaldehyde to rats to reveal effects on the development of atopic dermatitis in infantile and adolescent periods. These protocols have been successfully applied to several experiments and can be used for other substances.

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-1ß 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.

Brief Isolation Changes Nociceptive Behaviors and Compromises Drug Tests in Mice.

Herding with a litter is known to comfort rodents, whereas isolation and grouping with noncagemates provoke stress. The effects of stress induced by isolation and grouping with noncagemates on pain responses, and their underlying mechanisms remain elusive. We assessed the effect of isolation, a common condition during behavioral tests, and of grouping on defecation and pain behaviors of mice. Fecal pellets were counted 2 hours after exposure to the test chamber. It is significantly more in the isolated mice than in the grouped mice. Hindpaw withdrawal threshold and withdrawal latency were adopted as the indicatives of mechanical and thermal pain sensitivities, respectively. Interestingly, isolated mice showed higher pain thresholds than mice grouping with cagemates, and even those with noncagemates, indicating analgesic effects. Such effects were reduced by intrathecal injection of 0.01 mg/kg of naloxone (opioid receptor antagonist), atosiban (oxytocin and vasopressin receptor antagonist), and ketanserin (5-HT receptor antagonist). Intraperitoneal delivery of 1 mg/kg of naloxone and atosiban, but not ketanserin, also alleviated the isolation-induced analgesic effects. In contrast, these drugs at the same dose had no significant effect on the mice grouping with cagemates. In addition, the effect of morphine on thermal pain was more robust in the mice grouping with cagemates than in the isolated mice. These data demonstrated that brief isolation caused analgesia, mediated by endogenous opioidergic, oxytocinergic, and serotonergic pathways. These results indicate that isolation during pain behavioral tests can affect pain responses and the efficacy of drugs; thus, nociception tests should be conducted in grouping.