Junichi Hosoi

Regulation of cytokine expression in macrophages and the Langerhans cell-like line XS52 by calcitonin gene-related peptide.

Calcitonin gene‐related peptide (CGRP) inhibits antigen presentation by Langerhans cells (LC) and macrophages, and LC are anatomically associated with CGRP‐containing epidermal nerves. To determine whether CGRP may produce some of its functional effects through regulation of cytokine expression, we utilized enzyme‐linked immunosorbent assay (ELISA) of conditioned supernatants to examine production of interleukin (IL)‐10 and IL‐1β protein in the LC‐like cell line XS52 as well as the reverse transcriptase‐polymerase chain reaction (RT‐PCR) to examine levels of mRNA for IL‐10, IL‐1β, and the 40‐kDa subunit (p40) of IL‐12. CGRP augmented the lipopotysaccharide (LPS) and granulocyte‐macrophage colony‐stimulating factor (GM‐CSF) ‐induced release of IL‐10 protein and the induced expression of IL‐10 mRNA in these cells. However, it suppressed the induction of release of IL‐1β protein and the induction of mRNA for IL‐12 p40 and IL‐1β by LPS and GM‐CSF. Regulation of cytokine expression in peritoneal macrophages was also examined. By ELISA, the LPS‐induced expression of IL‐10 was augmented by CGRP, whereas the induction of IL‐1β was suppressed. Northern analysis demonstrated augmentation of LPS‐induced IL‐10 mRNA levels and inhibition of LPS‐induced IL‐1β mRNA by CGRP. CGRP inhibited the LPS‐induced induction of IL‐12 mRNA as assessed by RT‐PCR. Up‐regulation of B7‐2 expression by LPS and GM‐CSF was suppressed by CGRP in both XS52 cells and macrophages, as previously reported. This suppression, however, could be abrogated by co‐culture with neutralizing antibodies to IL‐10. Furthermore, the presence of neutralizing antibodies to IL‐10 during exposure of epidermal cells (EC) to CGRP prevented the CGRP‐mediated suppression of EC presentation of tumor‐associated antigens (from the S1509a spindle cell carcinoma) for elicitation of delayed‐type hypersensitivity in S1509a‐immune mice. These data suggest that suppression of antigen‐presenting function by CGRP is mediated, at least in part, by changes in cytokine expression that favor less robust antigen presentation for cell‐mediated immunity. J. Leukoc. Biol. 61: 216–223; 1997.

Catecholamines Inhibit the Antigen-Presenting Capability of Epidermal Langerhans Cells

The sympathetic nervous system modulates immune function at a number of levels. Within the epidermis, APCs (Langerhans cells (LC)) are frequently anatomically associated with peripheral nerves. Furthermore, some neuropeptides have been shown to regulate LC Ag-presenting function. We explored the expression of adrenergic receptors (AR) in murine LC and assessed their functional role on Ag presentation and modulation of cutaneous immune responses. Both purified LC and the LC-like cell lines XS52-4D and XS106 expressed mRNA for the ARs α1A and β2. XS106 cells and purified LC also expressed β1-AR mRNA. Treatment of murine epidermal cell preparations with epinephrine (EPI) or norepinephrine inhibited Ag presentation in vitro. Furthermore, pretreatment of epidermal cells with EPI or norepinephrine in vitro suppressed the ability of these cells to present Ag for elicitation of delayed-type hypersensitivity in previously immunized mice. This effect was blocked by use of the β2-adrenergic antagonist ICI 118,551 but not by the α-antagonist phentolamine. Local intradermal injection of EPI inhibited the induction of contact hypersensitivity to epicutaneously administered haptens. Surprisingly, injection of EPI at a distant site also suppressed induction of contact hypersensitivity. Thus, catecholamines may have both local and systemic effects. We conclude that specific ARs are expressed on LC and that signaling through these receptors can decrease epidermal immune reactions.

Tumor antigen presentation by epidermal antigen-presenting cells in the mouse : modulation by granulocyte-macrophage colony-stimulating factor, tumor necrosis factor α, and ultraviolet radiation

I‐A+ epidermal antigen‐presenting cells (APCs, Langerhans cells) have been shown to present tumor‐associated antigens (TAAs) and to induce tumor immunity in vivo. This study examined the effects of ultraviolet radiation (UVR) and the cytokines granulocyte‐macrophage colony‐stimulating factor (GM‐CSF) and tumor necrosis factor α (TNF‐α) on the ability of epidermal cells (ECs) to induce or to elicit immunity against the murine spindle cell tumor S1509a. Naive syngeneic mice were immunized three times at weekly intervals with ECs that had been cultured in GM‐CSF for 18 h and then pulsed with TAA derived from S1509a. This resulted in protective immunity against subsequent tumor challenge, providing a model to study the conditions required for sensitization against TAAs by epidermal APCs. Culture of ECs in GM‐CSF was required for induction of significant protective tumor immunity, and UV irradiation or incubation in TNF‐α for 2 h after GM‐CSF incubation abrogated the immunostimulatory effect of GM‐CSF. However, unlike UVR, TNF‐α did not significantly inhibit the induction of immunity when ECs were exposed to TNF‐α before overnight incubation in GM‐CSF, together with GM‐CSF, or after pulsing with TAA, and anti‐TNF‐α antibody treatment did not abrogate the effects of UVR on this system. Furthermore, TNF‐α incubation of ECs augmented their ability to elicit delayed‐type hypersensitivity (DTH) and also enhanced elicitation of DTH by GM‐CSF–cultured ECs, whereas UV‐irradiation reduced it in a dose‐dependent fashion. Taken together, these results demonstrate that GM‐CSF, TNF‐α, and UVR are significant regulators of tumor antigen presentation by epidermal APCs and that the effects of the cytokines examined differ with regard to induction or elicitation of immunity.

Glucocorticoids enhance Toll-like receptor 2 expression in human keratinocytes stimulated with Propionibacterium acnes or proinflammatory cytokines.

Toll-like receptors (TLRs) on keratinocytes are important cell surface receptors involved in the innate and acquired immune response to invading microorganisms. In acne vulgaris, TLR2 activation by Propionibacterium acnes (P. acnes) may induce skin inflammation via induction of various proinflammatory molecules that stimulate the invasion of inflammatory cells. Although corticosteroids themselves exert immunosuppressive or anti-inflammatory effects, it is well known clinically that systemic or topical glucocorticoid treatment provokes an acneiform reaction. Nevertheless, the effect of steroids on TLR2 expression in human keratinocytes remains unknown. Here, we found that the addition of glucocorticoids, such as dexamethasone and cortisol, to cultured human keratinocytes increased their TLR2 gene expression. Moreover, these glucocorticoids markedly enhanced TLR2 gene expression, which was further stimulated by P. acnes, tumor necrosis factor-alpha, and IL-1alpha. Gene expression of mitogen-activated protein kinase (MAPK) phosphatase-1 was also increased by the addition of dexamethasone. By using several inhibitors and activators, we found that TLR2 gene induction by glucocorticoids was mediated by the suppression of p38 MAPK activity following induction of MAPK phosphatase-1. These findings strongly suggest that steroid-induced TLR2 together with P. acnes existing as normal resident flora plays an important role in the exacerbation of acne vulgaris as well as in possible induction of corticosteroid-induced acne or in that of rosacea-like dermatitis.

Regulation of the cutaneous allergic reaction by humidity

Humidity is 1 of the environmental factors which regulate skin conditions. Effects of humidity on the cutaneous immune reaction were examined. Contact hypersensitivity to 2,4,6‐trinitrochlorobenzene was elicited in C57BL/6 mice. The reaction was greater in mice housed under low humidity conditions (about 10%) for 2 days, at either the induction or elicitation phase, than in mice housed under rather high humidity conditions (80%). After housing under controlled humidity for 2 days, the number of I‐A positive cells was 16% higher in the epidermis exposed to the dry condition. The increased population of FITC‐positive cells were in regional lymph nodes after painting of FITC during housing under lower humidity. Our study demonstrated that the cutaneous immune reaction is regulated by environmental humidity and suggested 2 possible mechanisms, i.e., increase in Langerhans cells and increased penetration of allergen with low humidity.

Regulation of plasma substance P and skin mast cells by odorants.

Background: Mast cells stimulate inflammation and itch sensation in the skin by releasing various mediators when they are activated. Stress exacerbates some skin diseases. We have reported that inhalation of certain odorants modulates immune reactions in the skin. Objective: The possible usage of odorants in the regulation of skin inflammation and itch sensation was to be examined. Methods: Female volunteers were subjected to interview stress with or without odorant inhalation. Mice were immobilized while inhaling odorants. Toluidene blue-stained sections were analyzed for activated mast cells. Plasma substance P level was determined by enzyme-linked immunoassay. Results: Interview stress induced plasma substance P only in volunteers who did not inhale odorants containing 2% 1,3-dimethoxy-5-methyl benzene (DMMB). Immobilization stress induced mast cell activation in mice and the activation was blocked by exposure to DMMB. Conclusions: Stress causes mast cell activation via an increase in substance P. The effect of stress is suppressed by inhalation of DMMB. SommaireAntécédents: Lorsqu’ils sont activés, les mastocytes stimulent l’inflammation et la sensation de démangeaison de la peau en raison des divers médiateurs qu’ils sécrètent. Le stress est un facteur d’exacerbation des maladies de la peau. Nous avons rapporté que l’inhalation de certains odorants module la réaction immunitaire de la peau. Objectif: Examiner l’utilisation possible d’odorants dans la régulation de l’inflammation et des sensations de démangeaison. Méthodes: Des femmes bénévoles ont été soumises àun stress d’entrevue avec ou sans inhalation d’odorants. Également, des souris ont été immobilisées durant l’inhalation d’odorants. Des sections colorées au bleu de Toluidine ont été analysées en vue de déceler des mastocytes activés. Le dosage immuno-enzymatique a révélé un niveau de substance plasmique P. Résultats: La substance plasmique P a été produite par le stress d’entrevue uniquement chezeles bénévoles qui n’ont pas inhalé d’odorant, contenant 2% 1,3-dimethoxy-5-methyl benzène (DMMB). Le stress d’immobilisation a causé une activation des mastocytes qui a été bloquée par l’exposition au DMMB. Conclusions: Le stress entraîine l’activation des mastocytes en augmentant la production de substance P. L’effet du stress est contrecarré par l’inhalation de DMMB.

Direct control of regulatory T cells by keratinocytes

Environmental challenges to epithelial cells trigger gene expression changes that elicit context-appropriate immune responses. We found that the chromatin remodeler Mi-2β controls epidermal homeostasis by regulating the genes involved in keratinocyte and immune-cell activation to maintain an inactive state. Mi-2β depletion resulted in rapid deployment of both a pro-inflammatory and an immunosuppressive response in the skin. A key target of Mi-2β in keratinocytes is the pro-inflammatory cytokine thymic stromal lymphopoietin (TSLP). Loss of TSLP receptor (TSLPR) signaling specifically in regulatory T (Treg) cells prevented their activation and permitted rapid progression from a skin pro-inflammatory response to a lethal systemic condition. Thus, in addition to their well-characterized role in pro-inflammatory responses, keratinocytes also directly support immune-suppressive responses that are critical for re-establishing organismal homeostasis.

Evaluation of psychological stress in confined environments using salivary, skin, and facial image parameters

Detecting the influence of psychological stress is particularly important in prolonged space missions. In this study, we determined potential markers of psychological stress in a confined environment. We examined 23 Japanese subjects staying for 2 weeks in a confined facility at Tsukuba Space Center, measuring salivary, skin, and facial image parameters. Saliva was collected at four points in a single day to detect diurnal variation. Increases in salivary cortisol were detected after waking up on the 4th and 11th days, and at 15:30 on the 1st and in the second half of the stay. Transepidermal water loss (TEWL) and sebum content of the skin were higher compared with outside the facility on the 4th and 1st days respectively. Increased IL-1β in the stripped stratum corneum was observed on the 14th day, and 7 days after leaving. Differences in facial expression symmetry at the time of facial expression changes were observed on 11th and 14th days. Thus, we detected a transition of psychological stress using salivary cortisol profiles and skin physiological parameters. The results also suggested that IL-1β in the stripped stratum corneum and facial expression symmetry are possible novel markers for conveniently detecting psychological stress.