Direct effects of glucocorticosteroids on epidermal Langerhans cells

Epicutaneous Administration of 17β-Estradiol Induces Langerhans Cells Depletion

BACKGROUND

Langerhans cells (LC) number and function in mouse vaginal mucosa are affected by 17β-estradiol (E₂) application; nonetheless, its effect on epidermal LC has not been studied. The purpose of this study was to evaluate the effect of topical administration of E₂ on the number, phenotype, and migratory ability of LC in mouse skin.

METHODS

Ears of adult CD1 male mice were topically treated once with several doses. Immunohistochemical staining for CD207 and TUNEL staining were performed. LC migration to lymph nodes and the effect on the expression of costimulatory molecules on cultured dendritic cells (DC) were also evaluated.

RESULTS

E₂ decreased the number of CD207+ LC in a dose-dependent manner. One hour after treatment, 1 and 10 µg/mL E₂ significantly reduced the LC number by 21% and 26%, respectively, after two hours, the reduction was 23% and 41%, respectively. After 48 hours, LC recovered, and after 96 hours of treatment, the CD207+/MHCII+ DC numbers were increased in regional lymph nodes. However, CD86 and CD40 molecules were expressed at lower levels than in positive control. The TUNEL assay did not show apoptotic cells. Furthermore, in cultured DC, E₂ promoted a decrease in CD40 and CD86 expression and an increase in CD273, CD274, MHCII, and CCR7.

CONCLUSIONS

The topical administration of E₂ induced a transitory local diminution of LC population and a tolerogenic phenotype. This decrease in epidermal LC suggests that E₂ may affect skin immune responses, inducing an inhibitory response, which should be considered when prescribing topical E₂ medications.

Duration of topical therapy in the maintenance of atopic dermatitis remission in pediatric age

BACKGROUND

Topical corticosteroids (TCS) are the first-choice treatment for atopic dermatitis (AD) flares. In literature there are clear advice about the potency, dosage and frequency of application of TCS, but there are no shared indications about duration of the treatment during a flare. The aim of the study is to demonstrate if the use of a steroid cream for less than or 5 days, could be equal or more effective than the application for more than 5 days during a flare episode, in keeping a remission state of AD.

METHODS

The study population (N.=122) was selected according to the following inclusion criteria: at least one specialist allergological and dermatological examination in the period November 2015 to February 2017, age between 1 and 11 years; mild to moderate atopic dermatitis. All patients were given a standardized telephone questionnaire, which concerns on multiple aspects: parents' self-reported perceptions of the severity of their child's condition; actual use of emollients, moisturizers and steroid creams; number of consecutive days of using of topical steroid cream during an exacerbation of AD; average number of AD exacerbations per month in the last year; total number of AD exacerbations in the last year.

RESULTS

Data from 96 patients was examined. We classified three groups of patients from data collected: group 1 (N.=40): use of TCS for ≤5 consecutive days during an exacerbation event of AD; group 2 (N.=12): use of TCS for >5 consecutive days during an exacerbation event of AD; group 3 (N.=44): nonuse of TCS or use of TCS with a different posology. We found a further subgroup in group 3 (3a, N.=27) with patients using only emollient crème in AD management. In group 1, 27 patients (67.5%) did not show a good AD control; on the contrary, 13 patients (27.5%) reported a good AD control. In group 2, 4 patients (25%) did not show a good AD control; on the contrary, 8 patients (75%) reported a good AD control. By comparing the data obtained in the presence of good AD control, the difference between the percentages obtained was found to be statistically significant (P=0.034).

CONCLUSIONS

The results obtained show that a therapeutic pattern based on the use of TCS for a duration of more than 5 consecutive days during an episode of AD exacerbation is more efficient than the proposed alternative therapeutic scheme in the maintenance of AD remission.

Stressful presentations: mild cold stress in laboratory mice influences phenotype of dendritic cells in naïve and tumor-bearing mice

The ability of dendritic cells (DCs) to stimulate and regulate T cells is critical to effective anti-tumor immunity. Therefore, it is important to fully recognize any inherent factors which may influence DC function under experimental conditions, especially in laboratory mice since they are used so heavily to model immune responses. The goals of this report are to 1) briefly summarize previous work revealing how DCs respond to various forms of physiological stress and 2) to present new data highlighting the potential for chronic mild cold stress inherent to mice housed at the required standard ambient temperatures to influence baseline DCs properties in naïve and tumor-bearing mice. As recent data from our group shows that CD8⁺ T cell function is significantly altered by chronic mild cold stress and since DC function is crucial for CD8⁺ T cell activation, we wondered whether housing temperature may also be influencing DC function. Here we report that there are several significant phenotypical and functional differences among DC subsets in naïve and tumor-bearing mice housed at either standard housing temperature or at a thermoneutral ambient temperature, which significantly reduces the extent of cold stress. The new data presented here strongly suggests that, by itself, the housing temperature of mice can affect fundamental properties and functions of DCs. Therefore differences in basal levels of stress due to housing should be taken into consideration when interpreting experiments designed to evaluate the impact of additional variables, including other stressors on DC function.

Glucocorticosteroids modify Langerhans cells to produce TGF-β and expand regulatory T cells

Although glucocorticosteroids (GCSs) have been used for many decades in transplantation and (auto)inflammatory diseases, the exact mechanisms responsible for their immunosuppressive properties are not fully understood. The purpose of this study was to characterize the effects of oral GCSs on the cutaneous immune response. We analyzed, by immunofluorescence staining and quantitative RT-PCR, residual skin biopsy material from a clinical study in which we had used oral GCS as positive control for determining the effects of candidate anti-inflammatory compounds on epicutaneous patch tests of Ni-allergic patients. Expectedly, oral GCS treatment led to a reduction of clinical symptoms and infiltrating leukocytes. Notably, we observed increased numbers of dermal FOXP3(+)CD25(+) T cells and epidermal Langerhans cells (LCs) that were associated with upregulated mRNA expression of TGF-β in lesions of GCS-treated Ni-allergic patients. To investigate this phenomenon further, we exposed purified LCs to GCS. They exhibited, in contrast to GCS-nonexposed LCs, 1) a more immature phenotype, 2) higher intracellular amounts of TGF-β, and 3) increased receptor activator for NF-κB expression, conditions that reportedly favor the expansion of regulatory T cells (Tregs). Indeed, we observed an enhancement of functionally suppressive FOXP3(+) T cells when CD3(+) cells were incubated with GCS-pretreated LCs. The expansion of Tregs was inhibited by TGF-β blockage alone, and their suppressive activity was neutralized by a combination of anti-TGF-β and anti-IL-10 Abs. Our data show that systemically applied GCSs endow LCs with Treg-promoting properties and thus shed new light on the mechanisms of GCS-mediated immunosuppression.

Immunology of skin transplantation

Untreated viable allogeneic skin is highly immunogenic. Epidermal Langerhans migrate after transplantation out of the donor skin into the lymph node of the recipient where they can activate T cells capable to mediate rejection. Allogeneic skin is used as a temporary coverage of burn wounds, often in combination with autologous skin grafts. Several methods to pretreat the allogeneic skin have been used to delay the rejection process. Processing of allogeneic skin in 85% glycerol results in a non-viable skin with a well-preserved structure. Experiments in a full thickness porcine wound model showed that rejection of glycerol treated allogeneic skin grafts was up to six days delayed. Viable, untreated allogeneic skin grafts were rejected predominantly by CD8 positive T cells whereas in the glycerol treated grafts the influx of host cells was lower and the majority of the cells were macrophages. The outgrowth of the autologous skin grafts underneath glycerol treated allogeneic skin was three days earlier completed when compared to grafts in combination with untreated allogeneic skin. Thus, by processing the allogeneic skin into 85% glycerol, the direct route to induce graft rejection is blocked since the Langerhans cells are non-viable. The glycerol-preserved skin grafts are finally rejected via an indirect route mediated by macrophages; this process is less disturbing for the outgrowth of autologous cells.

Lung cancer-derived bombesin-like peptides down-regulate the generation and function of human dendritic cells

Development of tumors is regulated by tumor-derived neuroendocrine factors, including bombesin-like peptides (BLP). We have evaluated neuroendocrine regulation of dendritic cell (DC) maturation and function by both tumor-derived and purified bombesin (BOM), neuromedin B (NMB), gastrin-releasing peptide (GRP), and a BOM antagonist D-Phe-bombesin (DPB). BOM, NMB and GRP dose-dependently inhibited maturation of DC assessed as down-regulation of CD40, CD80 and CD86 expression on DC. BOM and GRP also inhibited interleukin-12 (IL-12) production by DC and their ability to activate T cells. DPB partly abrogated immunosuppressive effect of tumor cells on DC. These data are a first evidence for the role of BLP in the regulation of DC maturation and function, demonstrating that BLP inhibit DC maturation and longevity in the lung cancer microenvironment. This suggests a new mechanism of tumor escape and provides new targets for the immunopharmacological correction of immune effectors in cancer.

Corticosteroids But Not Pimecrolimus Affect Viability, Maturation and Immune Function of Murine Epidermal Langerhans Cells

Given the importance of dendritic cells in the immune response, we investigated the effect of corticosteroids (CS) on the integrity, survival, and function of murine Langerhans cells (LC) in comparison with pimecrolimus, a novel anti-inflammatory drug for the topical treatment of atopic dermatitis. BALB/c mice were treated twice on one day with ethanolic solutions of the compounds. At 24-72 h after the last application, we observed fragmented DNA, caspase-3 activity, and an upregulation of CD95 expression in LC from mice treated with CS but not in LC of pimecrolimus- or vehicle-treated animals. CS-epidermal cell (EC) supernatants but not pimecrolimus-EC supernatants contained significantly lower amounts of soluble factors (GM-CSF, TNF-alpha, IL-1alpha) required for LC survival and maturation than EC supernatants from vehicle-treated mice. With regard to LC maturation, CS but not pimecrolimus inhibited the expression of CD25, CD205, and costimulatory molecules. In line with this, LC from pimecrolimus-treated mice were similar to LC from vehicle-treated mice in their capacity to stimulate antigen-presenting function and migration, whereas LC from CS-treated mice were greatly impaired in these abilities. In summary, our data show for the first time that CS but not pimecrolimus induce apoptosis in LC in situ, implying that the prolonged use of CS could have adverse effects on the skin immune system.

Thalidomide Inhibits Tumor Necrosis Factor-α Production and Antigen Presentation by Langerhans Cells

Thalidomide is an effective treatment for several inflammatory and autoimmune disorders including erythema nodosum leprosum, Behcet's syndrome, discoid lupus erythematosus, and Crohn's disease. Thalidomide is believed to exert its anti-inflammatory effects, at least in part, by inhibiting tumor necrosis factor-alpha (TNF-alpha) production by monocytes. We studied the effects of thalidomide on epidermal Langerhans cells (LC). LCs are epidermal antigen-presenting dendritic cells that play important roles in skin immune responses. Using the murine epidermis-derived dendritic cell lines, XS106A from A/J mice and XS52 from BALB/c mice as surrogates for LC, we found that thalidomide inhibited TNF-alpha production in a concentration-dependent manner. Northern blot analysis revealed that thalidomide significantly decreased the peak-induced mRNA level of TNF-alpha in XS106A cells and XS52 cells. We then examined the effect of thalidomide on fresh LC enriched to approximately 98% using positive selection of Ia+ cells with antibodies conjugated to magnetic microspheres. TNF-alpha production was reduced by 67.7% at a thalidomide concentration of 200 microg per mL. Thalidomide also had a profound inhibitory effect on the ability of LC to present antigen to a responsive TH1 clone. Thalidomide inhibits TNF-alpha production and the antigen-presenting ability of epidermal LCs. These mechanisms may contribute to the therapeutic effects observed with this agent.

Influence of immunosuppressive drugs on dendritic cells

Immunosuppressive drugs used to control allograft rejection and in efforts to promote transplant tolerance are well recognized for their abilities to inhibit lymphocyte activation and proliferation. In recent years, evidence has accumulated that these diversely acting agents (anti-proliferative drugs, calcineurin inhibitors, rapamycin, deoxyspergualin and glucocorticoids) also affect the development and functional immunobiology of dendritic cells, in vitro and in vivo. Here we review the influence of immunosuppressive drugs on the differentiation and function of these important antigen-presenting cells. We also consider how these effects influence immune reactivity and tolerance induction, implications for furthermore understanding of dendritic cell biology and prospects for improving the outcome of organ transplantation and therapy of other immune-mediated disorders by impacting dendritic cell function.

CX-659S, a diaminouracil derivative, indirectly inhibits the function of Langerhans cells by blocking the MEK1/2-Erk1/2 pathway in keratinocytes

Keratinocytes are an important component of the skin immune system, and keratinocyte-derived cytokines control the function of Langerhans cells. We previously showed that CX-659S, a novel diaminouracil derivative, had an inhibitory effect on hapten-induced contact hypersensitivity reaction in mice. In this study, we investigated the mechanism by which CX-659S elicits its inhibitory effect. CX-659S inhibited the expressions of CD80 and CD86, but not that of CD54, on Langerhans cells in epidermal cell suspensions. Exogenous granulocyte-macrophage colony-stimulating factor restored the CX-659S-induced inhibition of CD80 and CD86 expressions of Langerhans cells. The production of interleukin-2 from allogeneic T cells was also inhibited when the cells were stimulated with CX-659S-treated epidermal cells, and this inhibition was suppressed by the addition of granulocyte-macrophage colony-stimulating factor during CX-659S treatment. As CX-659S significantly inhibited production of granulocyte-macrophage colony-stimulating factor from keratinocytes, CX-659S was thought to indirectly affect Langerhans cells by inhibiting the function of keratinocytes. These effects of CX-659S were preceded by blockade of the phosphorylation of extracellular-signal-regulated kinase 1/2 and their direct activators, mitogen-activated protein kinase/extracellular-signal-regulated kinase 1/2 (MEK1/2), but not p38 mitogen-activated protein kinase or inhibitory nuclear factor kappaBalpha, in keratinocytes. Furthermore, a specific MEK1/2 inhibitor, U0126, mimicked the effect of CX-659S. CX-659S, a keratinocyte-response modifier, would be an effective therapeutic compound to inhibit contact hypersensitivity reaction, its action mechanism being different from those of other immunosuppressive agents such as glucocorticosteroids or cyclosporine A.

Identification and characterization of the low-affinity receptor for immunoglobulin E (FcepsilonRII/CD23) on murine Langerhans cells

CD23 is a low-affinity receptor for immunoglobulin E and expressed on various hemopoietic cells. Although human epidermal cultured Langerhans cells express CD23, the study to identify CD23 on murine Langerhans cells has so far failed. In this study, using highly enriched (> 95%) Langerhans cells from murine epidermis obtained by the panning method, we investigated whether murine Langerhans cells express CD23. As the result of a series of experiments using fluorescence activated cell sorter analysis and the polymerase chain reaction method, it was revealed that CD23 is expressed on cultured Langerhans cells, but not on freshly isolated Langerhans cells. Comparison of the DNA sequence of polymerase chain reaction products of CD23 from cultured Langerhans cells with that from spleen leukocytes demonstrated that there were the same sequences between the two polymerase chain reaction products. The expression of CD23 on cultured Langerhans cells was downregulated when Langerhans cells were cultured with keratinocyte-derived cytokines: interleukin-1alpha, interleukin-18, macrophage colony-stimulating factor, or granulocyte-macrophage colony-stimulating factor. Moreover, it was shown that murine IgE bound to cultured Langerhans cells and this binding was partially inhibited when Langerhans cells were cultured with monoclonal antibody against CD23 (B3B4). Thus this study revealed murine cultured Langerhans cells do express CD23 and the discrepancy from previous reports may be due to the influence of cytokines derived from keratinocytes. Furthermore, the finding that murine cultured Langerhans cells bind IgE through CD23 suggests that CD23 on murine Langerhans cells may be involved in IgE-mediated immune responses.

Identification of delta- and mu-type opioid receptors on human and murine dendritic cells

The purpose of this study was to evaluate mu- and delta-opioid receptors (OR) on human and murine dendritic cells (DC). Expression of mu- and delta-OR mRNA on DC was demonstrated by RT-PCR. The immunocytochemical and Western blot analyses revealed the expression of OR protein in DC. Radioreceptor assay demonstrated the specific saturated temperature-dependent binding of [3H]-labeled opioid ligand on DC and B(max)=2.8+/-0.3 fmol/10(6) cells and K(D)=4.8+/-1.0 nM were calculated by a Scatchard analysis. Finally, OR ligands DADLE and DAGO dose-dependently modulated the capacity of DC to induce T cell proliferation in an MLR assay. Importantly, expression of functional OR on DC was significantly increased upon TNF-alpha-induced DC maturation. Thus, these data suggest a new mechanism of opioid-dependent neuroendocrine immunomodulation.

Human epidermal Langerhans' cells are targets for the immunosuppressive macrolide tacrolimus (FK506)

BACKGROUND

The immunosuppressive macrolide tacrolimus (FK506) has been shown to inhibit allergic contact dermatitis in animal models as well as in human beings. More recently, successful treatment of atopic dermatitis with an ointment containing tacrolimus has been reported.

OBJECTIVES

We explored the effects of this compound on epidermal Langerhans' cells (LCs), which are known to play an important pathophysiologic role in inflammatory skin diseases.

METHODS

The expression of the intracellular FK506 binding protein (FKBP12) was monitored on freshly isolated and cultured epidermal LCs. Phenotyping and functional exploration of LCs treated with different concentrations of tacrolimus and beta-methasone valerate (betaMv) were performed.

RESULTS

FKBP12 is expressed in freshly isolated LCs but is lost while they are maturating into mature dendritic cells. Tacrolimus inhibited the expression of IL-2R (CD25) and of the costimulatory molecules CD80 (B7.1) and CD40. Expression of MHC class I and II was also affected, whereas CD86 (B7.2) expression was not altered. In contrast, betaMv strongly increased the expression of CD25. Paradoxically, while decreasing CD40 and MHC class I expression, betaMv significantly increased the expression of MHC class II, CD80, and CD86 on cultured LCs but impaired their allostimulatory activity. Tacrolimus was about 100 times more potent than betaMv at inhibiting LC stimulatory function.

CONCLUSION

Tacrolimus can exert immunopharmacologic alterations on LCs, which may account, at least in part, for the therapeutic effect of this compound in eczematous skin diseases.

Recruitment of CD1a+ Langerhans cells to the nasal mucosa in seasonal allergic rhinitis and effects of topical corticosteroid therapy

BACKGROUND

Local antigen presentation may be necessary for both primary and recall T-cell responses to grass pollen in hay fever patients. We examined the effect of seasonal allergen exposure on nasal mucosal antigen-presenting cell (APC) populations and the effects of topical corticosteroid therapy.

METHODS

Nasal biopsies were collected from 46 grass pollen-sensitive seasonal rhinitis patients before the grass-pollen season. A second biopsy was collected during the pollen season, when patients had received 6 weeks' treatment with either fluticasone propionate (200 microg, twice daily) or placebo. Cell populations in biopsy sections were quantified by immunocytochemistry.

RESULTS

Significant increases in submucosal and epithelial CD1a+ Langerhans cells, but not CD68 + macrophages or CD20 + B cells, were observed during the pollen season. Seasonal increases in CD1a+ Langerhans cells were inhibited by corticosteroid therapy.

CONCLUSIONS

Recruitment of CD1a+ Langerhans cells to the nasal mucosa during natural seasonal allergen exposure may contribute to local T cell responses. Topical corticosteroids may act, at least in part, by inhibiting effective allergen presentation to T cells through inhibition of recruitment of Langerhans cells to the nasal mucosa.

Differential effects of cytokines and immunosuppressive drugs on CD40, B7-1, and B7-2 expression on purified epidermal Langerhans cells1

Langerhans cells are MHC class II antigen-positive antigen-presenting cells in the epidermis. Recent studies have revealed that Langerhans cells express costimulatory molecules like B7-1 and B7-2 and the accessory molecule CD40. Although these molecules are important for the antigen-presenting function of Langerhans cells, little is known about the precise regulation of their expression on purified Langerhans cells. Using a panning technique, we purified epidermal Langerhans cells to around 95% purity. Freshly prepared Langerhans cells (fLC) expressed the mRNA for receptors for M-CSF (cfms), GM-CSF (GM-CSFR), and TNF-alpha (TNFRII). TNF-alpha markedly upregulated CD40 and B7-1 expression on Langerhans cells, but not B7-2 expression. GM-CSF moderately upregulated B7-1 and B7-2 expression, and slightly upregulated CD40 expression. M-CSF moderately upregulated B7-1 expression, but did not modulate CD40 or B7-2 expression. Dexamethasone (DEX) markedly inhibited CD40, B7-1, and B7-2 expression on Langerhans cells. Cyclosporin A (CsA) and FK506 slightly inhibited CD40 and B7-1 expression on Langerhans cells, but not B7-2. Furthermore, TNF-alpha restored the DEX-induced inhibition of CD40 expression on Langerhans cells, but not the inhibition of B7-1 or B7-2 expression. GM-CSF restored DEX-induced inhibition of CD40, B7-1, and B7-2 expression. M-CSF did not affect the DEX-induced inhibition of these molecule expressions. These data provide a better understanding of the role of selective cytokines and immunosupressive drugs in the modulation of the antigen-presenting capacity of Langerhans cells.

Apoptosis in dendritic cell biology

Apoptosis or programmed cell death regulates many aspects in immunological homeostasis and, thus, controls the initiation, magnitude, duration, and termination of immune responses. Recent studies on dendritic cells (DC), including Langerhans cells (LC), have reinforced this concept by documenting that these antigen presenting cells express surface receptors and ligands that are known to mediate apoptotic cell death and that they are highly susceptible to apoptotic signals. In this review article, four major topics concerning apoptosis in the biology of DC will be overviewed: (a) molecular mechanisms of apoptosis; (b) DC apoptosis induced by various stimuli; (c) regulation of DC apoptosis; and (d) cross-priming and cross-tolerance induced by DC ingesting apoptotic bodies.

Effects of topical testosterone propionate on the positive nickel patch test

In a group of nickel sensitized women, we investigated the effects of topical application of testosterone propionate on the epidermic density of CD1 + dendritic cells and on the response to patch tests performed with scaled nickel concentrations. In a significant number of examined subjects, treatment with testosterone propionate induced an increase of the minimum eliciting dose of nickel and an evident reduction of CD1 + dendritic cell epidermic density. In those subjects in which the minimum eliciting dose resulted unmodified, the epidermic density of CD1 + dendritic cells also did not undergo significant variations following treatment with testosterone propionate. This parallelism between the behaviour of the responses to patch tests and the epidermic density of CD1 + dendritic cells induces us to think it possible that testosterone propionate is able to increase the tolerance to contact with allergen by interfering with the activity of Langerhans cells. The possible mechanisms of testosterone action on Langerhans cells remain to be elucidated.

A novel mechanism of glucocorticoid-induced immune suppression: the inhibiton of T cell-mediated terminal maturation of a murine dendritic cell line

Working with the murine epidermal-derived dendritic cell (DC) line XS52, we have observed previously that antigen-specific interaction with T cells stimulates their "terminal maturation" into fully professional DC. In this study we examined the impact of dexamethasone (DEX) on this T cell-induced event. When added to cocultures of XS52 DC and the KLH-specific Th1 clone HDK-1 in the presence of antigen, DEX at relatively low concentrations (10(-9)-10(-7) M) prevented substantially or completely each of the changes that typify terminal maturation, including (a) secretion of relatively large amounts of IL-1beta, IL-6, and TNFalpha; (b) loss of CD115 (colony-stimulating factor-1 receptor) expression and proliferative responsiveness to colony-stimulating factor-1; and (c) elevated expression of CD86 (B7-2). XS52 cells also underwent terminal maturation upon exposure to lipopolysaccharide alone, and DEX also inhibited effectively each of the same changes, indicating that DC can serve as the direct target of DEX. By contrast, DEX inhibited XS52 DC-stimulated IL-2 secretion by HDK-1 T cells, but not other changes that accompany T cell activation, including the secretion of IFNgamma and TNFalpha and the elevated expression of CD25, CD28, and CD44. These results reveal a new immunosuppressive mechanism of glucocorticoid action, that is, direct inhibition of T cell-mediated terminal maturation by DC.

Effect of coadministration of corticosteroids on the development of contact sensitization

BACKGROUND

Transdermal administration of drugs can increase patient compliance and reduce side effects, but it can also cause contact sensitization. Corticosteroids frequently are used to suppress the local immune response; however, their use as a pretreatment for transdermal system application sites is not practical.

OBJECTIVE

Our purpose was to determine the feasibility of suppressing contact sensitization by delivering a corticosteroid with the transdermal delivery systems.

METHODS

Materials were applied continuously for 3 weeks to the same (protocol SS) or different (protocol AS) skin sites. Skin flux and appearance of sensitization were determined.

RESULTS

Coadministration of hydrocortisone reduced the incidence of sensitization by d-chlorpheniramine and benzoyl peroxide from 45% to 7.5% and from 20% to 2.3%, respectively, under protocol SS. Under protocol AS, sensitization by d-chlorpheniramine was reduced from 15% to 1%. Frequent exposure to the sensitizer plus corticosteroid induced tolerance to the sensitizer.

CONCLUSION

Sensitization by moderately immunogenic drugs after any length of exposure may be reduced to acceptable levels by the coadministration of hydrocortisone.

Granulocyte-macrophage colony-stimulating factor overrides the immunosuppressive function of corticosteroids on rat pulmonary dendritic cells

Pulmonary dendritic cells (DC) are present in extremely small numbers, but they are the most potent antigen-presenting cells in the lungs. Pure populations of DC can be isolated from the lung following collagen digestion, Percoll gradient centrifugation, removal of phagocytic cells and flow cytometric sorting for cells which exhibit high levels of surface major histocompatibility complex (MHC) class II molecules. Exogenous GM-CSF enhances this immunostimulatory capacity of the pulmonary DC. Soluble factors produced by type II airway epithelial cells and interstitial macrophages also enhance the immunostimulating capacity of pulmonary DC while alveolar macrophages suppress it. Thus, the function of DC may be regulated by locally produced cytokines. Corticosteroids are widely used as immunosuppressive agents in pharmacotherapy. While these agents are known to inhibit T cell proliferation and macrophage activation, their effects on DC are not known. We found that dexamethasone (Dex) pretreatment resulted in about a 50% reduction in the immunostimulatory capacity of rat pulmonary DC. This was associated with downregulation of MHC class II (Ia) expression. Dex-induced suppression of DC function could be restored with GM-CSF. We conclude that corticosteroids downregulate antigen-presenting capacity by direct suppression of pulmonary DC. This immunosuppressive effect of corticosteroids on DC may, however, be abrogated by exogenous GM-CSF. Corticosteroids and GM-CSF are therapeutic agents with potent direct immunomodulating effects on DC.

Histochemical, immunohistochemical and ultrastructural studies on the action of glucocorticoids on epidermal Langerhans cells (ELC) of murine skin

We studied the influence of the glucocorticosteroids dexamethasone and prednisolone on epidermal Langerhans cells (ELC) in the ear skin of BALB/c mice. ELC were detected by HLA II-antigen-expression and ATPase staining. The number of ELC was counted by normal light and immunofluorescence microscopy. Both, dexamethasone and prednisolone decreased the number of ELC and the intensity of the reaction for HLA II and ATPase significantly. In the electron microscope, ELC were identified by their light cytoplasm, the lobulated nucleus and typical Birbeck Granula (BG). After systemic application of dexamethasone or prednisolone the ultrastructure was changed with respect to a loss of typical BG and occurrence of numerous small vacuoles without electron dense content instead of BG.

Immune-modulatory drugs alter Candida albicans-induced sleep patterns in rabbits

To evaluate the influences of immune responsiveness on sleep alteration during infectious disease, sleep was monitored during Candida albicans infection in rabbits treated with immune-modulating drugs. Intravenous administration of C. albicans to normal rabbits initially increased and subsequently decreased both the amount of slow-wave sleep (SWS) and delta-wave amplitudes (DWA) during SWS. Cortisone treatment attenuated these effects. The immunosuppressive drug cyclosporine did not alter the initial enhancement of SWS, but did attenuate the C. albicans-induced reduction in SWS time and potentiate the reduction in DWA. In contrast, administration of incomplete Freund's adjuvant and prior immunization with killed C. albicans, which were expected to enhance immune responsiveness, did not markedly alter C. albicans-induced alterations in SWS. However, the immune stimulant levamisole potentiated the effects of C. albicans on SWS. These data indicate that pharmacologic treatments expected to alter immune responsiveness modulate microbially induced sleep, and are consistent with the hypothesis that facets of the immune response mediate sleep changes during infectious disease.

Up-regulation of CD44 expression by tumor necrosis factor-alpha is neutralized by interleukin-10 in Langerhans cells

CD44 is a principal cell-surface receptor for hyaluronate and is found on a wide variety of cells. CD44 plays an important role in lymphocyte homing, lymphohemopoiesis, and T-cell activation as well as in cell motility and migration. CD44 is expressed on the cell surface of epidermal Langerhans cells (LC), and is one of the candidates for molecules that are involved in the migratory capability of LC, but little is known about its regulatory properties. We examined the modulatory effects of tumor necrosis factor (TNF)-alpha and interleukin (IL)-10 on the CD44 expression in LC. We found 1) that TNF-alpha significantly up-regulated the expression of CD44 in a concentration-dependent manner, 2) that IL-10 down-regulated the expression of CD44 in a concentration-dependent manner, 3) that the effect of TNF-alpha or IL-10 was readily detectable as early as 24 h after the initiation of culture, and 4) that the simultaneous addition of TNF-alpha and IL-10 mutually neutralized the effect of each other. These data suggest that in the epidermal microenvironment the expression of CD44 in LC may be reciprocally regulated by TNF-alpha and IL-10, both of which are known to be produced by surrounding keratinocytes.

Comparative analysis of B7-1 and B7-2 expression in Langerhans cells: differential regulation by T helper type 1 and T helper type 2 cytokines

Epidermal Langerhans cells (LC) are Ia-bearing potent antigen-presenting cells (APC) of dendritic cell lineage that play a crucial role in primary and secondary T cell-dependent immune responses. LC express several costimulatory molecules such as B7, which has been implicated as one of the important determinants of professional APC. Recently, B7 antigens have been shown to include three distinct molecules termed B7-1, B7-2, and B7-3, and the expression of B7-1 and B7-2 in LC has been already confirmed. However, little is known of the regulation of B7-1 and B7-2 expression in LC. We demonstrated that LC do not express B7-1 and B7-2 in situ; however, the expression of both molecules is rapidly induced during the first 3 days of culture, and high levels of expression are maintained at least until day 6. We show that the expression of B7-2 in LC is much higher than that of B7-1 in each experiment, and that B7-1 and B7-2 expression is reproducibly augmented by interleukin (IL)-4 in a dose-dependent manner; however, IL-2 affected expression very little. Finally, B7-1 expression is significantly and dose-dependently down-regulated by interferon (IFN)-gamma or IL-10, and B7-2 expression is consistently inhibited by IL-10, but not by IFN-gamma. The effects of these cytokines are active only in the induction phase (during first 3 days of culture) of B7 expression: the modulatory effects of cytokines are hardly detected in the plateau phase (days 4 to 6 of culture) of B7 expression in LC. These findings suggest that B7-1 and B7-2 expression are indeed selectively and differentially regulated by these T cell-derived cytokines, and that the cytokines may modulate the synthesis of B7 molecules rather than the degradation of already-expressed B7 molecules.

B7-1 expression of Langerhans cells is up-regulated by proinflammatory cytokines, and is down-regulated by interferon-gamma or by interleukin-10

Langerhans cells (LC) act as potent antigen-presenting cells (APC) for primary and secondary T cell-dependent immune responses. LC express several costimulatory and/or adhesion molecules such as B7/BB1, which has been implicated as one of the important determinants for professional APC. Recent studies have shown that B7/BB1 antigens comprise three distinct molecules termed B7-1, B7-2, and B7-3. We have examined the regulatory properties of B7-1 expression in LC using various cytokines including interleukin (IL)-1 alpha, IL-1 beta, IL-2, IL-3, IL-4, IL-5, IL-6, IL-7, IL-10, interferon (IFN)-gamma, granulocyte/macrophage colony-stimulating factor (GM-CSF), and tumor necrosis factor (TNF)-alpha. We have demonstrated: 1) that the B7-1 expression of LC is reproducibly up-regulated by either GM-CSF, TNF-alpha, IL-1 alpha, IL-1 beta, or IL-4 in a dose- and time-dependent manner, 2) that GM-CSF exhibits the most active effect on B7-1 up-regulation in each experiment, 3) that IFN-gamma or IL-10 profoundly inhibits the B7-1 expression of LC in a dose- and time-dependent manner, and 4) that the down-regulatory ability of IFN-gamma or IL-10 neutralizes the activity of up-regulatory cytokines. The enhancing or inhibitory action of these cytokines on B7-1 expression occurs selectively because none of the cytokines consistently affects I-A expression of LC. These data suggest that the B7-1 expression of LC may be dynamically regulated by these up- and down-regulatory cytokines in normal and inflammatory epidermal microenvironment.

Selective regulation of ICAM-1 and major histocompatibility complex class I and II molecule expression on epidermal Langerhans cells by some of the cytokines released by keratinocytes and T cells

Epidermal Langerhans cells (LC) are major histocompatibility complex (MHC) class II (Ia)-positive dendritic cells that act as potent antigen-presenting or accessory cells for primary and secondary T cell-dependent immune responses. Recent studies have disclosed that the morphological, functional, and phenotypic characteristics of LC are variably and drastically modulated by external stimuli both in vivo and in vitro. However, little is known of the biological significance of diverse cytokines in regulating the surface molecules of LC. To determine the regulatory properties of ICAM-1, Ia, and MHC class I (H-2K) molecules in LC, we have examined the effects of interleukin (IL)-1 alpha, IL-1 beta, IL-2, IL-3, IL-4, IL-5, IL-6, IL-7, IL-10, interferon-gamma (IFN-gamma), tumor necrosis factor-alpha (TNF-alpha), and granulocyte-macrophage colony-stimulating factor (GM-CSF) on the expression of these molecules. Among the cytokines examined, IFN-gamma markedly and reproducibly up-regulates the expression of H-2K, but not ICAM-1, in Ia+ LC in a time- and dose-dependent manner. TNF-alpha consistently up-regulates the expression of ICAM-1, but not H-2K, in a time- and dose-dependent manner. IL-10 slightly but reproducibly inhibits the expression of ICAM-1, but not H-2K, in a time- and dose-dependent manner. IL-10 potently inhibits the TNF-alpha-induced ICAM-1 up-regulation, but not the IFN-gamma-induced H-2K up-regulation. Moreover, no cytokine consistently affects the Ia expression of LC. In addition, slight enhancing effects have been observed on H-2K expression by IL-4, and on ICAM-1 expression by IL-1 alpha, IL-1 beta, or GM-CSF. The present data suggest that the selective regulation is operative in a certain cell surface moiety of LC by various cytokines. These results further facilitate our understanding of immunobiology of LC.

Activated human Langerhans cells express mRNA for IL-1 alpha and IL-1 beta and produce these cytokines but do not secrete them

Human Langerhans cells (LC) were isolated from epidermal cell preparations by panning with mouse anti-CD1 monoclonal antibody. RNA was prepared and probed for the presence of mRNAs for various cytokines using radiolabeled cDNAs. After stimulation with phorbol myristate acetate LC express RNA for interleukin 1 alpha (IL-1 alpha) and interleukin 1 beta (IL-1 beta) and produce proteins but do not secrete them at detectable levels. LC-associated IL-1, particularly IL-1 alpha, may play a role in antigen presentation. PMA did not induce IL-6 expression in LC. The addition of lipopolysaccharide, a muramyl dipeptide analog, ionomycin, IL-1 alpha, tumor necrosis factor-alpha, insulin-like growth factor-1 or IL-6 did not induce IL-1 mRNA in LC. UVB augmented IL-1 beta mRNA expression. Glucocorticoids did not detectably affect IL-1 alpha or IL-1 beta mRNA levels following PMA induction, however, staurosporin inhibited IL-1 beta mRNA synthesis. Thus the inducers and regulators of IL-1 formation in human LC and monocytes are not identical.

Selective activation of circulating CD4+ lymphocytes in severe adult atopic dermatitis

An analysis of peripheral blood lymphocyte subsets and their expression of activation markers was performed using flow cytometry in 12 adult patients with severe atopic dermatitis, and compared with 14 normal individuals. Repeated measurements were made over an 8-week period during which disease activity was also assessed. Increased percentages of activated and unactivated CD4+ lymphocytes, and decreased percentages of CD8+ cells were observed in atopic dermatitis. Increasing disease activity was associated with an increase in the proportion of activated and unactivated CD4+ lymphocytes and a fall in the proportion of CD8+ cells. This study demonstrates that in adults with severe atopic dermatitis, increasing disease activity is associated with selective activation of CD4+ lymphocytes and a relative expansion of the CD4+ cell subset.

Immune events in skin. I. Spontaneous cluster formation of dendritic (veiled) cells and lymphocytes from skin lymph

To investigate the mechanism of spontaneous attachment of afferent lymph lymphocytes to dendritic cells, cells from canine skin lymph were used. There were 3.3 +/- 2.8% of veiled cells in clusters found in lymph flowing from the cannulated lymph vessel. The number of clusters forming ex vivo in the collected lymph samples increased as a function of time and was temperature dependent. Incubation of cells with proteolytic enzymes or monosaccharides did not alter cell interactions. The ability of veiled cells to bind lymphocytes was independent of divalent cations but reduced by xylocaine and retinoic acid. Among steroids only methylprednisolone showed an inhibitory effect on cluster formation. Indomethacin and acetylsalicylic acid had no blocking activity on cell binding. Also, no effect was seen after treatment with cyclosporine A and azathioprine. An enhanced cluster formation after desialation with neuraminidase was observed. The desialated cells were cultured in order to study their stimulatory and accessory cell functions. No enhancement of autologous mixed leucocyte reaction was seen, but a significantly higher responsiveness to a suboptimal dose of phytohaemagglutinin was observed. The N-ase-mediated non-specific cell attachment could be abrogated by cell washing or treatment with EDTA or xylocaine. This study indicates that cluster formation by skin lymph veiled cells and lymphocytes is a spontaneous process which cannot be controlled by means usually effective in regulating the in vitro induced clustering of antigen-stimulated cells.

Langerhans' cells in equine cutaneous papillomas and normal skin

Langerhans' cells (LC) were investigated immunohistochemically and electron microscopically in normal equine epidermis and 133 equine cutaneous papillomas experimentally induced in five 2-year-old Thoroughbred horses. Class II major histocompatibility complex antigen-positive dendritic LC were found in the normal epidermis and ultrastructurally had the characteristic Birbeck's granules. In the developing phase of the papillomas, LC were significantly decreased in number and size, indicative of a hypofunctional state. In the regressing phase of the papillomas, LC were markedly increased in number, especially at the epidermis-dermis junction. LC with long dendrites were rich in cytoplasm with well-developed cytoplasmic organelles, including Golgi apparatus, lysosomes, Birbeck's granules, and multivesicular bodies. These LC were hyperfunctional. An infiltration of many T lymphocytes was also observed at the epidermis-dermis junction.

In-vivo administration of interleukin 1 both enhances and suppresses contact sensitivity in the mouse

The in-vivo effects of systemic administration of recombinant human interleukin 1 beta (rIL-1 beta) were studied in the mouse contact-sensitivity model. rIL-1 beta in a single dose of 20 micrograms injected intraperitoneally 72-48 h before or 2-24 h after sensitization suppressed contact sensitivity. Given before challenge rIL-1 beta modulated the response in a biphasic way with an enhancement at 48 h and a suppression at 2 h before challenge. Only microgram doses of rIL-1 beta could enhance the contact sensitivity at 48 h, while microgram doses of rIL-1 beta at 2 h before challenge suppressed and nanogram doses enhanced the response. Treatment with indomethacin could only abrogate the effects of nanogram doses of rIL-1 beta. Measurements of the thickness of unchallenged control ears revealed that rIL-1 beta by itself could cause a small but significant increase in thickness depending on the dose and the time of administration.

Langerhans cells but not monocytes are capable of antigen presentation in vitro in corticosteroid contact hypersensitivity

Corticosteroids suppress delayed-type hypersensitivity (DTH) reactions in vivo and impair lymphoid cell functions in vitro. In contact hypersensitivity (CHS) to corticosteroids, however, the corticosteroids are capable of inducing DTH responses in vivo. The present study examined the capacity of corticosteroids to induce in vitro proliferation of T lymphocytes from patients with CHS to corticosteroids. With peripheral blood mononuclear adherent cells as antigen-presenting cells (APC) and hydrocortisone-17-butyrate (H-17-B) as hapten, no proliferation responses were detected of T lymphocytes from patients with CHS to H-17-B. However, when epidermal Langerhans cells (LC) were used as APC, weak proliferation responses were observed.

Immunosuppressive effects of clonidine on the induction of contact sensitization in the balb/c mouse

The clonidine transdermal therapeutic system (clonidine-TTS) has been associated with a significant incidence of allergic contact sensitization. This incidence was not predicted by premarket skin sensitization testing in animals or humans. One possible explanation lies in recent findings in guinea pigs that clonidine exposure could inhibit the elicitation of skin reactions to unrelated strong contact sensitizers. However, these studies also showed that clonidine pretreatment did not appear to affect the induction of contact sensitization. On this basis, we sought to specifically evaluate the induction phase of sensitization to clonidine as an alternative means of assessing its sensitization properties. The method selected was the assay of in situ lymphocyte proliferation in lymph nodes draining the sites of clonidine exposure, a method recently promoted as an alternative means to assess contact allergenic potential. Utilizing various induction application techniques and regimens, we were consistently unable to demonstrate clonidine's allergenic potential through such an assessment of lymphocyte proliferation. We were also unable to demonstrate sensitization by in vivo ear swelling or in vitro lymphocyte blastogenesis assay techniques. However, a subsequent assessment of the effect of clonidine exposure on the induction of sensitization to unrelated strong contact allergens demonstrated a consistent 40-70% inhibition of the proliferative response to the contact allergens oxazolone and trinitrochlorobenzene. This was similar to the degree of suppression produced by the corticosteroids fluocinonide and hydrocortisone when they were tested at 80 and 10 times lower concentrations. In addition, we observed a comparable inhibition of the ear swelling response to oxazolone. These data extend our knowledge of the immunomodulatory effects of clonidine and offer additional mechanistic insights into the failure of short-term predictive patch-test methods to detect this chemical's potential to induce allergic contact sensitization.