Immunohistochemical study of beta-adrenergic receptors in the psoriatic epidermis using an anti-alprenolol anti-idiotypic antibody

Autoradiographic mapping of beta-adrenoceptors in human skin

A high density of beta 2-adrenoceptors has been found in human skin. Using autoradiographic mapping we investigated the distribution of beta 1- and beta 2-receptors in normal and diseased human skin. Cryostat sections of human skin obtained at biopsy were incubated with [125I]-iodocyanopindolol and nonspecific binding was identified by incubation of adjacent sections with 200 microM (-)-isoproterenol; beta 2-receptors were visualized using CGP 20712A and beta 1-receptors using ICI 118,551 as competing agents. The epidermis was densely labelled with an even distribution throughout all layers. Most of the beta-receptors were of the beta 2-subtype, with practically no beta 1-receptors. beta-Receptors were also localized to eccrine sweat glands, dermal blood vessels, and perivascular inflammatory cells, but there was no labelling of sebaceous glands. Topical glucocorticoids caused an increase in the density of epidermal beta-receptors. We conclude that keratinocytes and eccrine sweat glands express high densities of beta 2-receptors, suggesting that they may have a physiological role in the regulation of these cells.

1,25-Dihydroxyvitamin D3 increased beta-adrenergic adenylate cyclase response of fetal rat keratinizing epidermal cells (FRSK cells)

Using fetal rat keratinizing epidermal cells (FRSK), the effects of 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) on adenylate cyclase system were investigated. The beta-adrenergic adenylate cyclase response was significantly increased by the stimulation of 1 x 10(-7) M 1,25(OH)2D3. The effect was observed by 6 h and continued for at least 48 h. The 1,25(OH)2D3-induced beta-adrenergic augmentation effect was dose-dependent and the maximal response was observed at a concentration of 1 x 10(-7) M 1,25(OH)2D3. Other adenylate cyclase systems (adenosine, prostaglandin E2 and histamine) were not affected by treatment with 1,25(OH)2D3. The thymidine incorporation in FRSK cells was not significantly affected by 1,25(OH)2D3 treatment. Forskolin-induced cyclic AMP accumulation was significantly increased by 1,25(OH)2D3 treatment. Cholera toxin-induced cyclic AMP accumulation was moderately increased, but this was statistically not significant. Northern blot hybridization showed that none of the mRNAs (the beta 2-adrenergic receptor, the alpha subunits of the stimulatory or inhibitory guanine nucleotide binding proteins, Gs alpha, Gi2 alpha, Gi3 alpha) were significantly altered by 1,25(OH)2D3 treatment. We have already reported that the beta-adrenergic response was increased by dexamethasone and inhibited by retinoids in FRSK cells. The addition of both 1,25(OH)2D3 and dexamethasone to the incubation medium resulted in an additive augmentation. On the other hand, the beta-adrenergic augmentation by the 1,25(OH)2D3 treatment was suppressed by the addition of all trans-retinoic acids. Our results indicate that 1,25(OH)2D3 induces beta-adrenergic augmentation without an alternation of thymidine incorporation of FRSK cells.

Retinoid-induced beta-adrenergic inhibitory effect associated with increased thymidine incorporation of fetal rat keratinizing epidermal cells (FRSK cells)

Using fetal rat keratinizing epidermal cells (FRSK cells) we investigated the effects of retinoids on the cyclic AMP system. The beta-adrenergic adenylate cyclase response was significantly decreased by the treatment of cells with 1 x 10(-6) M Ro 10-1670. The effect was observed by 12 h and remained for at least 48 h. The decreased beta-adrenergic response was accompanied by increased adenosine- and forskolin-induced cyclic AMP accumulations. Thymidine incorporation of FRSK cells was also increased by the retinoid treatment. Northern blot hybridization showed that none of the messages (the beta2-adrenergic receptor, the stimulatory guanine nucleotide binding protein (Gs-alpha), or the inhibitory guanine nucleotide binding proteins (Gi-2 alpha, Gi-3 alpha)) were significantly altered by the retinoid treatment. We have already reported that the beta-adrenergic response as well as the beta2-adrenergic receptor mRNA is increased by the dexamethasone treatment of FRSK cells. The addition of both Ro 10-1670 and dexamethasone in the incubation medium resulted in the loss of the beta-adrenergic augmentation effect by dexamethasone. These results indicate that retinoids decrease the beta-adrenergic response and increase the thymidine incorporation of FRSK cells. This is contrary to the previous results using pig epidermal organ culture system.

Expression of interferon-gamma receptors in normal and psoriatic skin

Psoriatic keratinocytes have a reduced antiproliferative response to interferon (IFN)-gamma, and HLA-DR expression is usually not observed on keratinocytes in psoriatic plaques despite the presence of activated T cells. We have therefore compared the expression of IFN-gamma receptors in psoriatic skin with that of normal human skin. Using mouse monoclonal antibodies and immunoperoxidase staining on cryostat cut sections, we detected IFN-gamma receptors on keratinocytes throughout the epidermal layers except stratum corneum in normal skin (n = 11). Biopsy specimens from involved psoriatic skin (n = 17) consistently showed a staining pattern that differed from that of normal skin in that only the lower part of epidermis reacted with the antibodies to IFN-gamma receptors, whereas the upper layers showed no or minimal staining. Expression of IFN-gamma receptors in uninvolved psoriatic skin (n = 16) did not differ from that of healthy controls. Forty-five percent of the biopsies from lesional psoriatic skin displayed ICAM-1 positive keratinocytes, and only two specimens had a limited expression of HLA-DR reactive keratinocytes. The decreased binding of antibodies against the IFN-gamma receptors in the upper part of psoriatic epidermis might be secondary to abnormal maturation of psoriatic keratinocytes or a primary defect involving abnormal modulation of IFN-gamma receptors.

The specificity and cellular origin of phenylethanolamine N-methyltransferase (PNMT)-like immunoreactivity in psoriatic skin

Phenylethanolamine N-methyltransferase (PNMT)-like immunoreactivity has been found in psoriatic skin and in this study, PNMT-like immunoreactivity was investigated in the involved and uninvolved skin of six patients with lichen planus and four patients with lichen simplex. No PNMT immunoreactivity was observed in these diseases. Studies were carried out using cultured fibroblasts from two patients with psoriasis from uninvolved and involved areas of skin and from two controls using antibodies to PNMT, as well as antibodies to the chemical messengers somatostatin, substance P, parathyroid hormone and peptide histidine isoleucine amide. No immunoreactivity to these substances was found, and fibroblasts are unlikely to be the cellular origin of the PNMT-like immunoreactivity as seen in psoriatic skin.

Cholera toxin- and forskolin-induced cyclic AMP accumulations of pig skin (epidermis). Modulation by chemicals which reveal the beta-adrenergic augmentation effect

Effects of cholera toxin and forskolin on pig epidermal adenylate cyclase system were investigated. Both agents increased cyclic AMP levels of epidermis. Marked accumulations were observed in the presence of cyclic AMP phosphodiesterase inhibitor, isobutylmethylxanthine (IBMX). It has been known that hormone-stimulated adenylate cyclase responses are modified by various chemical treatments. Following long term incubation with hydrocortisone, Ro10-1670, and colchicine, the epidermal beta-adrenergic adenylate cyclase response was increased without the alteration of cyclic AMP phosphodiesterase activity. Adenosine-, and histamine-adenylate cyclase responses were unchanged by hydrocortisone treatment, and were decreased by Ro10-1670 and colchicine treatments. Following the long term incubation with these chemicals, effects of cholera toxin and forskolin were investigated. Colchicine-treated skin revealed the increased cholera toxin-, and forskolin-induced cyclic AMP accumulations. Neither hydrocortisone- nor Ro10-1670-treated skin revealed alterations of cholera toxin-, and forskolin-effect. The stimulatory effect of colchicine on the cholera toxin-, and forskolin-effect was observed at doses of the beta-adrenergic augmentation effect. Our results indicate that among the chemicals which reveal the beta-adrenergic augmentation effect, colchicine is unique in that it also increases cholera toxin-, and forskolin-induced cyclic AMP accumulations of epidermis.

Increased cholera toxin-, and forskolin-induced cyclic AMP accumulations in psoriatic involved versus uninvolved or normal human epidermis

Psoriatic involved epidermis reveals variously altered receptor-adenylate cyclase responses; among them the most prominent is defective beta-adrenergic adenylate cyclase response, which is normally the major receptor-adenylate cyclase system of human epidermis. It is known that activation of hormone-stimulated adenylate cyclase, a membrane-bound enzyme complex, requires functional coupling of at least 3 distinct subunits: 1) receptor subunit (R), 2) guanine nucleotide binding protein (G), and 3) catalytic subunit (C). The precise nature of the beta-adrenergic defect in the psoriatic epidermis, however, remains to be determined, especially in terms of G and C function. Using the involved and uninvolved skin from psoriatic patients, we investigated effects of cholera toxin (which monitors G-C interaction) and forskolin (which monitors C function) on the adenylate cyclase system of epidermis, which were compared with those of normal human epidermis. Both agents increased cyclic AMP levels of involved, uninvolved, and normal human epidermis. Marked accumulations were observed in the presence of cyclic nucleotide phosphodiesterase inhibitor, isobutyl-methylxanthine (IBMX); without the phosphodiesterase inhibitor, the effect of each agent was minimal. Comparison of the effects of cholera toxin revealed that the psoriatic involved epidermis accumulates much more cyclic AMP than the uninvolved epidermis (involved: 193 +/- 65; uninvolved: 117 +/- 54 pmoles/mg protein/5 h). Similarly forskolin-induced cyclic AMP accumulations of the involved epidermis were much more than those of uninvolved epidermis (involved: 374 +/- 152; uninvolved: 101 +/- 41 pmoles/mg protein/2 h). Those of normal human epidermis were not significantly different from those of uninvolved epidermis (cholera toxin: 99 +/- 36 pmoles/mg protein/5 h; forskolin: 84 +/- 22 pmoles/mg protein/2 h). Our results indicate that G and C function and their interaction is not defective (but rather increased) in the psoriatic involved epidermis. This suggests that the defective beta-adrenergic response of psoriatic involved epidermis reflects defective R or R-G interaction of the epidermal adenylate cyclase system.