Cyclic AMP, cyclic GMP, and glucocorticoids as potential metabolic regulators of epidermal proliferation and differentiation

New and emerging biologic therapies for moderate-to-severe plaque psoriasis: mechanistic rationales and recent clinical data for IL-17 and IL-23 inhibitors

The development of effective and well-tolerated biologic therapies has advanced the management of psoriasis by enabling clinicians to treat underlying disease mechanisms. Biologics approved for the treatment of moderate-to-severe psoriasis include three tumor necrosis factor alpha inhibitors and an interleukin-12/interleukin-23 inhibitor. The establishment of the immunological basis of psoriasis has led to the development of biologic agents targeting specific downstream mediators in the psoriatic cascade. These drugs inhibit cytokines and cytokine signaling/transcription mediators like interleukin-17, which plays an important role in immunopathogenesis. Several interleukin-17 inhibitors are undergoing phase 3 clinical studies. In addition, biologics that selectively inhibit interleukin-23 have been assessed in phase 2 studies. This review describes how the dissection of pathways in the immunopathogenesis of psoriasis has led to the development of therapeutic agents and highlights the latest clinical efficacy, safety and tolerability data on new and emerging biologic therapies that selectively target interleukin-17 or interleukin-23.

Lithium and psoriasis: what primary care and family physicians should know

OBJECTIVE

This review focuses on the association of lithium treatment and psoriasis. The mechanism of action of lithium in causing psoriasis and the clinical presentation of psoriasis secondary to lithium treatment are considered.

DATA SOURCES

A search of the literature from 1949 to 2007 was performed using MEDLINE, with the following search terms: lithium, psoriasis, skin, dermatology, and psychodermatology.

DATA SYNTHESIS

Lithium is involved in a variety of cutaneous reactions including psoriasis, which may present as exacerbation of preexisting psoriasis, induction of de novo psoriasis, pustular psoriasis, nail changes, and psoriatic arthropathy. The appearance of psoriatic lesions may occur at normal therapeutic serum lithium levels. The refractory period for the development of psoriatic lesions is variable and generally longer in induction and shorter in exacerbation of psoriasis. Lithium-induced psoriasis is often resistant to conventional treatment modalities, and some cases may require dose reduction or discontinuation of lithium treatment.

CONCLUSION

Lithium is the mainstay of treatment in bipolar disorder and is associated with a variety of cutaneous side effects including psoriasis. Primary care providers and family physicians should be knowledgeable about the association of lithium and its dermatologic side effects. Early recognition and management could be beneficial in avoiding the issues of noncompliance and further deterioration of mood symptoms secondary to obviously disfiguring skin appearance. Primary care, psychiatry, and dermatology liaison services will prove helpful in managing these patients.

Relative similarity within purine nucleotide and ligand structures operating on nitric oxide synthetase, guanylyl cyclase and potassium (K ATP, BK Ca) channels

OBJECTIVES

Purine nucleotides play a central role in signal transduction events initiated at the cell membrane. The NO-cGMP-cGK pathway, in particular, mediates events involving NOS and some classes of K(+) ion channel. The aim of this study is to investigate relative molecular similarity within the ligands binding to NOS, K(ATP), BK(Ca) channels and regulatory nucleotides.

METHODS

Minimum energy conformers of the ligand structures were superimposed and fitted to L-arginine and the nucleotides of adenine and guanine using a computational program.

KEY FINDINGS

Distinctive patterns were evident in the fitting of NOS isoform antagonists to L-arginine. K(ATP) channel openers and antagonists superimposed on the glycosidic linkage and imidazole ring of the purine nucleotides, and guanidinium and ribose groups of GTP in the case of glibenclamide. The fits of BK(Ca) channel openers and antagonists to cGMP were characterized by the linear dimensions of their structures; distances between terminal oxy groups in respect of dexamethasone and aldosterone.

CONCLUSIONS

The findings provide structural evidence for the functional interaction between K(+) channel openers/antagonists and the regulatory nucleotides. Use of the purine nucleotide template systematizes the considerable heterogeneity evident within the structures of ligands operating on K(+) ion channels.

Cutaneous adverse effects of lithium: epidemiology and management

Acneiform eruption, psoriasis, folliculitis, and maculopapular eruption have been described as adverse reactions to lithium therapy. In controlled studies, patients treated with lithium developed more cutaneous reactions, particularly acne and psoriasis, than patients receiving other psychotropics, with a prevalence in lithium-treated patients as high as 45%. Male patients taking lithium are more susceptible to developing cutaneous reactions than their female counterparts. Lithium tends to worsen or precipitate cutaneous conditions that are characterized by the pathological findings of neutrophilic infiltration. As lithium-related cutaneous adverse effects can be distressing to patients and may affect medication compliance, attention should be paid to skin problems in patients receiving lithium therapy. Management without cessation of lithium therapy is usually feasible except in some patients with psoriasis that is resistant to treatment. Paradoxically, therapeutic effects of topically applied lithium have been noted in seborrheic dermatitis and recurrent herpes infections.

A highly decreased binding of cyclic adenosine monophosphate to protein kinase A in erythrocyte membranes is specific for active psoriasis

A cyclic adenosine monophosphate binding abnormality in psoriatic erythrocytes that could be corrected by retinoid treatment has been reported. It was tested whether this binding abnormality is specific for psoriasis and the effects of treatment were compared with etretinate, cyclosporine A, or anthralin on 2-(3)H-8-N(3)-cyclic adenosine monophosphate binding to the regulatory subunit of protein kinase A in erythrocyte membranes. One hundred and fifteen individuals were evaluated, including: (i) 34 healthy persons; (ii) 15 patients with nonatopic inflammatory skin diseases (eczema, erythroderma, tinea, Grover's disease, erysipelas, urticaria); (iii) eight with other dermatoses mediated by immune mechanisms (systemic lupus erythematosus, lichen planus, necrotizing vasculitis, erythema nodosum, systemic sclerosis); (iv) 14 with generalized atopic dermatitis; and (v) 44 with psoriasis vulgaris clinically assessed by Psoriasis Area and Severity Index. In psoriasis, the course of the binding of 2-(3)H-8-N(3)-cyclic adenosine monophosphate to erythrocytes was measured in nine patients during a 10 wk treatment with etretinate, in 21 patients during a 10 wk treatment with cyclosporine A, and one patient under topical treatment with anthralin for 4 wk. We found the following femtomolar binding per mg protein: (i) healthy persons (1064 +/- 124, mean +/- SD); (ii) nonatopic inflammatory skin diseases (995 +/- 103); (iii) immune dermatoses (961 +/- 92); (iv) atopic dermatitis (960 +/- 110); and (v) psoriasis (645 +/- 159; p < 0.0001 compared with nonpsoriatics, Mann-Whitney U test). Treatment of psoriasis with etretinate, cyclosporine A, or anthralin normalized the binding of cyclic adenosine monophosphate, which was inversely correlated to the Psoriasis Area and Severity Index score. It was concluded that the decreased binding of cyclic adenosine monophosphate to protein kinase A in erythrocytes is specific for psoriasis and normalizes after successful treatment.

Lithium therapy associated with hidradenitis suppurativa: case report and a review of the dermatologic side effects of lithium

Lithium is frequently used in the management of several psychiatric disorders including acute mania, bipolar (manic-depressive) disorder, and recurrent depression. We describe a patient in whom hidradenitis suppurativa developed while the patient was receiving lithium. The cutaneous side effects of lithium are reviewed. The most frequent are psoriasis, acneiform lesions, folliculitis, alopecia, and a maculopapular/macular eruption. Many of these side effects respond less readily to conventional therapy while the patient is receiving lithium.

Psoriasis induced by interferon-alpha

Recombinant human interferon-alpha has been used in the treatment of several cancers, but there have been several reports that it may exacerbate psoriasis or trigger off its onset. We report four patients, three of whom first developed psoriasis and one who had an aggravation of the condition during treatment with interferon-alpha. Three of the patients had the carcinoid syndrome and one a renal carcinoma, and all were treated with interferon-alpha 2b or 2a (IFN-alpha 2b, 2a) with doses ranging from 1.5 x 10(6) U daily to 18 x 10(6) U three times weekly. In two of the patients there appeared to be a correlation between the severity of the psoriasis and the dosage of interferon.

Modulation of epidermal terminal differentiation in patients after long-term topical corticosteroids

The expression of the various markers for terminal epidermal differentiation in atrophic skin of patients after long-term topical corticosteroids (TCS) was studied by electron microscopy, immunofluorescence using antibody to profilaggrin/filaggrin (PF/FG), immunoperoxidase staining using antibody to involucrin, and oil red O stain for neural lipids of the stratum corneum. Thirty-nine patients were subdivided into two groups: (A) 19 patients suffering from rebound phenomenon after stopping TCS and (B) 20 patients without rebound phenomenon. Biopsy specimens were taken before ending the use of TCS in both groups. In group A, both the morphological markers (including the different epidermal strata, keratohyalin granules, lamellar granules, and cornified cell envelopes) and the molecular markers (including involucrin, PF/FG, and neutral lipids) of terminal epidermal differentiation were significantly suppressed. On the other hand, the differentiational markers in the atrophic skin of patients without rebound phenomena were only slightly altered. These results suggest that potent TCS not only has antiproliferative actions but also inhibits the differentiation of epidermis, resulting in structural defects in the epidermis, especially the stratum corneum.

A deficient function of the antioxidative system of the organism as an aetiopathogenetic factor in psoriasis

The main idea of a new hypothesis about the aetiopathogenesis of psoriasis concerns the significance of interrelation between pro- and antioxidants, vitamin A-dependent keratin synthesis and proliferation of keratinocytes. On the basis of postulated deregulation in the antioxidative system of the organism, we explain the predisposition, the initiation and pathogenesis of lesions, their persistence and resolution and the operation mechanisms of antipsoriatics.

Exacerbation of psoriasis during lithium treatment

Exacerbation of psoriasis was observed in a 28-year-old patient following the addition of lithium carbonate to a treatment regimen of carbamazepine and other drugs for manic-depressive psychosis. The biopsied lesion histologically showed a typical psoriasiform tissue reaction and immunohistochemically, remarkable infiltration of activated helper T cells. Immunologic reaction to lithium in a patch test and a lymphocyte proliferation test could not be demonstrated. The mechanisms of lithium action and their relations to the exacerbation of psoriasis were reviewed. In this patient, although we could not define which effect of lithium was most important, it seemed that an increased blood lithium level combined with simultaneous carbamazepine administration enhanced the triggering effect of lithium and caused the exacerbation of psoriasis.

Surgical treatment of psoriasis: a review including a case report of dermabrasion of hypertrophic psoriatic plaques

Psoriasis is a chronic papulosquamous disease. Koebner and reverse Koebner reactions have been described. Surgical treatments which produce a reverse Koebner reaction in psoriasis are reviewed and a case of dermabrasion of resistant, hypertrophic plaques is presented. These procedures are to be considered only when conventional therapy fails.

Drugs in exacerbation of psoriasis

Drugs that have been associated with the precipitation or exacerbation of psoriasis include lithium, beta adrenergic receptor blocking agents, and antimalarials. The withdrawal of corticosteroids has been reported to activate pustular psoriasis. Nonsteroidal anti-inflammatory drugs, such as indomethacin, have recently been reported to exacerbate psoriasis, although additional well-controlled studies are still needed. Drugs used for treatment of psoriasis will sometimes cause a flare because of irritation, phototoxicity, or hypersensitivity reaction resulting in a Koebner phenomenon. Because psoriasis is a very complex disease and its activity is often unpredictable, clinical studies on adverse drug effects on psoriasis have been difficult to conduct. This review evaluates clinical, histologic, and biochemical evidence in the literature for drug-associated onset or exacerbation of psoriasis.

Psoriasis and alpha-interferon

Two patients with metastatic renal carcinoma who were treated with recombinant-DNA-derived alpha-interferon (rIFN alpha) had exacerbation of concomitant psoriasis, and another patient experienced onset of psoriasis during treatment with rIFN alpha. This suggests that interferons may participate in the pathophysiology of psoriasis.

Activity of some lysosomal enzyme in rheumatoid and psoriatic arthritis

In order to study the function of polymorphonuclear leukocytes in patients suffering from psoriatic and rheumatoid arthritis and psoriasis vulgaris the release of beta-glucuronidase, elastase and cytoplasmic lactate dehydrogenase was investigated. The life of polymorphonuclear leukocytes in rheumatoid and psoriatic arthritis is shorter. Polymorphonuclears from patients with psoriasis and psoriatic arthritis release, with as well as without phagocytic stimulation by zymosan, more lysosomal enzymes into extracellular space then cells of healthy controls. The total content of LDH and of lysosomal enzymes in leukocytes of patients suffering from all three forms of disease were not altered in comparison with the amount in PMNL of healthy subjects.

Colchicine-induced alteration of hormone-stimulated cyclic AMP synthesis in pig skin (epidermis)

Effects of colchicine on the epidermal adenylate cyclase systems were investigated. When pig skin (epidermis) was incubated in RPMI 1640 medium without the addition of serum, the beta-adrenergic adenylate cyclase response (epinephrine-induced cyclic AMP accumulations) gradually decreased, whereas adenosine and histamine responses remained high or increased during the long-term (up to 48 h) incubation period. The addition of colchicine (1 mumol/liter) in the incubation medium resulted in an increase in the beta-adrenergic responsiveness and a decrease in adenosine and histamine responsivenesses. The effects of colchicine were both time- and concentration-dependent; they could be observed after 9-12 h incubation, and the maximal effect was obtained at a concentration of 0.1 mumol/liter. Similar effects were observed by the addition of another microtubule-disruptive agent, vinblastine. On the other hand, cytochalasin B, which affects the microfilament system, apparently decreased the beta-adrenergic response and increased adenosine and histamine responses during the long-term incubation period. The addition of serum in the incubation medium resulted in essentially the same effect as that of colchicine; in the presence of serum, colchicine-treated skin responded much more markedly to epinephrine (and much less to adenosine and histamine) than the control skin after 24- and 48-h incubation. Previously we reported that hydrocortisone has similar potentiating effects on the beta-adrenergic system of epidermis. The comparison of the effects of both compounds revealed that colchicine had a stronger effect than hydrocortisone, and furthermore, the simultaneous addition of both compounds (colchicine and hydrocortisone) in the incubation medium resulted in the more marked increase of beta-adrenergic response than the single addition of each chemical. Our overall results, coupled with the finding that hydrocortisone has no toxic effects on the adenosine- or histamine-adenylate cyclase system of epidermis, suggest that colchicine affects epidermal adenylate cyclase systems probably through a mechanism that is independent of glucocorticoid (hydrocortisone) effect.

Lithium adverse reactions in psychiatric patients

A brief review of the literature on the adverse reaction of lithium therapy in man is presented. This was aimed at both toxic and side effects of lithium on various organ systems of the body. Inconclusive, insufficient or conflicting data were found in several areas of possible lithium-induced toxicity, notably in lithium-associated nephrotoxicity. Results of prospective studies are needed to clarify this issue. Adverse reactions derived from continued administration of lithium salts with neuroleptic medications or with electroconvulsive therapy were also reviewed. Lithium-induced side effects on the endocrine and gastrointestinal systems were also summarized along with both dermatologic and ophthalmologic effects. The teratogenicity of lithium during pregnancy and its cardiovascular abnormalities were discussed. The target organs of lithium poisoning and their management were also presented.

The effect in vivo of alterations in gonadotropins and cyclic nucleotides on oocyte maturation in the hamster

The temporal relationship of changes in cAMP and cGMP to oocyte maturation was examined in proestrous hamsters (day 4). The first series of experiments showed, in normal cycling hamsters, an increase in cAMP and a decrease in cGMP at 1400 h shortly after the rise in LH with oocyte maturation beginning at 1800 h. When a second group of animals was injected with phenobarbital at 1200 h to block the LH surge, no significant change occurred in either cyclic nucleotide and oocyte maturation was prevented. In the second series of experiments single injections of either saline, hCG (30 IU), LH (10 micrograms) or FSH (10 micrograms) were given each to a group of animals at 0900 h on day 4. Animals were killed at five time intervals between 15 min and 3 h following the injection. LH and hCG stimulated a simultaneous increase in cAMP and decline in cGMP. The injection of FSH, however, did not cause an increase in cAMP but still produced a sharp decline in cGMP. Oocyte maturation occurred at 3 h in those animals injected with gonadotropins. Animals injected with saline showed neither cyclic nucleotide changes nor oocyte maturation. When cAMP and cGMP levels were expressed as a ratio (cAMP/cGMP) a significant increase occurred in the normal cycling animals and in those injected at 0900 h with gonadotropins. Phenobarbital and saline injected control animals showed no significant increase in the cAMP/cGMP ratio and no oocyte maturation. The results of these experiments and previous studies by this investigator indicate that cGMP may play an important role in oocyte maturation in the hamster prior to the LH surge. Since, in the presence of gonadotropins, the cAMP/cGMP ratio increases prior to oocyte maturation, it may be that the cyclic nucleotide ratio is also of importance in this process. Previous work by Hubbard and Terranova (1) has shown that guanosine 3':5' cyclic monophosphate (cGMP), can inhibit spontaneous maturation of hamster oocytes in vitro. This inhibitory action was dose dependent and overcome by LH. The cGMP-mediated inhibition occurred only in cumulus-enclosed oocytes, while adenosine 3':5' cyclic monophosphate (cAMP) inhibited spontaneous maturation in both cumulus-enclosed and denuded oocytes. The results of this study suggested that cGMP may play a role in inhibiting oocyte maturation prior to the LH surge. LH, the initiator of oocyte maturation, has also been shown in the intact proestrous rat and hamster to cause a decrease in cGMP at the same time that cAMP is rising (2,3).(ABSTRACT TRUNCATED AT 400 WORDS)

Effects of glucocorticoids on the beta-adrenergic adenylate cyclase system of pig skin

Effects of glucocorticoids on the epidermal beta-adrenergic adenylate cyclase system were investigated. Long-term incubation of pig skin slices in RPMI 1640 medium resulted in the gradual decrease in the epinephrine-induced cyclic AMP accumulations of skin. The addition of hydrocortisone (100 microM) in the incubation medium prevented this decrease, and after 24- and 48-h incubation, there was a marked difference in beta-adrenergic responsiveness between control and hydrocortisone-treated skin. The study using other steroid hormones revealed that this effect on the beta-adrenergic system was relatively specific for glucocorticoids. Hydrocortisone, prednisolone, dexamethasone, and beta-methasone-17-valerate were shown to have marked effects on the beta-adrenergic system, while androstenedione, testosterone, dihydrotestosterone, progesterone, estrone, and beta-estradiol had no effect. Cortisone and estriol were shown to have similar but weaker effects than hydrocortisone. The effect of glucocorticoids was also relatively specific to the beta-adrenergic system, since there was no significant difference in adenosine-or histamine-induced cyclic AMP accumulations of skin after long-term incubation with and without hydrocortisone. The mechanism of this glucocorticoid action does not seem to be through the simple protection of the beta-adrenergic system of the skin, since the addition of hydrocortisone in the incubation medium at 24 or 48 h incubation time, when the epinephrine-induced cyclic AMP accumulation was considerably decreased, reversed the epinephrine unresponsiveness of the skin, after the additional 24-h incubation. Furthermore, the effect of hydrocortisone was inhibited by 3 different kinds of inhibitors: (a) progesterone, an inhibitor of intracytoplasmic glucocorticoid receptor binding; (b) actinomycin D, an inhibitor of messenger RNA (mRNA) synthesis; and (c) cycloheximide, an inhibitor of protein synthesis at the translation step. These results are in accordance with the view that glucocorticoids affect the beta-adrenergic system of epidermis by a mechanism requiring mRNA and protein synthesis possibly through the intracytoplasmic glucocorticoid receptor system of epidermis.

Rapid modulation of keratinocyte differentiation by the external environment

The ultrastructural differentiation of epidermal keratinocytes cultured in the presence of 3T3 feeder cells is significantly different from that of the epidermis in vivo. Several markers of keratinization, including keratohyaline granules (KGs), membrane-coating granules (MCGs), and an enucleated stratum corneum are essentially absent from cultured cells. When cultured rabbit epidermal cells were trypsinized and injected subcutaneously into athymic mice, the cells reaggregated and formed cysts lined with a stratified squamous epithelium morphologically resembling the in vivo epidermis. In this paper, we examined the differentiation of the injected cells by electron microscopy. Within 24 h after injection, MCGs and KGs appeared in the reaggregated epidermal cells. Horny cells were noted within 48 h. Since basement membrane formation was not completed until much later (between 4-9 days), a direct contact between epidermal cells and a continuous basal lamina structure was not required for the formation of various keratinization markers. Glycogen and lipid droplets, which were abundant in the early (10-48 h) cystic epithelia, gradually disappeared from the basal through the granular layers during days 2-9. By 16 days, the ultrastructure of the cystic epithelium appeared similar to the in vivo rabbit epidermis including the formation of "rabbit-type" KGs, MCGs, and normal enucleated horny cells. These results provided further evidence that the differentiation of epidermal cells can be modulated significantly and reversibly by the external environment. Moreover, the expression of certain morphologic markers of keratinization (KGs and MCGs) can be modulated rapidly by the growth environment.

Effect of hydrocortisone on the adenylate cyclase system of the skin--in vitro explant study

We have previously reported the effect of hydrocortisone (HC) on the adenylate cyclase system of pig epidermis. HC had no effect on the basal level of cyclic AMP but there was an increased adrenaline-induced cyclic AMP accumulation when epidermal slices were incubated for more than 6 h with HC. This incubation did not alter the responsiveness to histamine. We are interested in the effects on epidermal cells of HC, which may act through the adenylate cyclase system. It is well documented that adrenaline, histamine and adenosine stimulate adenylate cyclase and cause an accumulation of cyclic AMP in pig epidermis. An increased cyclic AMP results in the inhibition of mitosis and epidermal outgrowth. Employing the rate of epidermal outgrowth and mitotic index as indicators of cyclic AMP effect, we studied the effect of HC on the adenylate cyclase system. The pretreatment with HC (100 microM) magnified the inhibitory effect of adrenaline on epidermal outgrowth and mitosis, whereas the inhibitory effect of histamine or adenosine was not affected by HC. It is suggested that HC induced an increased responsiveness of adenylate cyclase to adrenaline, resulting in a magnified inhibitory effect of adrenaline on epidermal outgrowth and mitosis.

Evidence of diurnal variation of human epidermal cell proliferation. I. Epidermal 3H-labeling index and serum cortisol rhythm

Performing two longitudinal studies over 48 and 66 h, respectively, in 12 healthy male adult volunteers the epidermal LI were measured by in vitro 3H-thymidine labeling technique every 6 h and serum cortisol levels simultaneously by RIA examination. While serum cortisol showed a circadian rhythm over the whole test period, a circadian rhythmic pattern of epidermal LI yet became evident 12 h after the onset of experiments. This initial time lag in appearance of LI periodicity may be due to some temporal desynchronization in the cell cycle of keratinocytes. Circadian peaks and minima of both cortisol and LI were found to be inversely correlated, with a time-shifting of 6 h according to the experimental conditions. The present results reveal strong evidence that circadian fluctuation of endogenous cortisol secretion does influence the regulation of epidermal DNA-synthesis in man.

Effects of trypsin on the cyclic AMP system of the pig skin

Trypsin increased cyclic AMP levels of the pig skin. This effect was markedly potentiated by the cyclic nucleotide phosphodiesterase inhibitor theophylline. Without theophylline this trypsin-induced cyclic AMP accumulation was transient and the maximal accumulation was noted by 5 min. Soybean trypsin inhibitor inhibited this trypsin-induced cyclic AMP accumulation. After the trypsin treatment, marked acantholysis was noted histologically and the decreased responsiveness to other adenylate cyclase stimulators was seen. The decrease of the epinephrine response was most marked and that of histamine response was much less. Both low and high Km cyclic nucleotide phosphodiesterase activities were decreased by the trypsin treatment. However, at 5 min incubation time, when the increase in cyclic AMp level was most marked, the decrease in the phosphodiesterase activities was minimal. Trypsin seems to reveal its action through the proteolytic activation of adenylate cyclase system of the skin.

Influence of intercellular agents on proliferation and gene activity of cultured human skin epithelium cells (NCTC 2544)

"Human skin epithelium cells" (NCTC strain 2544; HSEpicell) are established cells and grow to a monolayer the same way as epithelial cells. Addition of proliferating or antiproliferating substances results in a typical dose-dependent influence on the cell growth: steroids inhibit mitosis, polyamines stimulate proliferation, while prostaglandin E2, theophylline and papaverine reduce cell growth. Since the pattern of chromosomal nonhistone proteins indicates alterations of gene activity, DNA-binding proteins of HSE picells are analysed. Compared to native human skin fibroblasts (La Col 1115) there are only slight differences, in contrast to cancer cells. Therefore HSE picells may represent undifferentiated non-cancer cells. Hydrocortisone and theophylline inhibit cell proliferation by different mechanisms. As indicated by the pattern of DNA-binding proteins, both substances also act on HSEpicells in two different ways. As HSEpicells can be used for studying cell regulation, water-soluble extract and DNA-binding proteins of psoriatic scales as well as sera of psoriasis patients are tested in respect to any proliferating component. However, no influence on cell proliferation could be found.

Inhibition of epidermal adenyl cyclase by lithium carbonate

An in vitro floating system was used to investigate the effect of lithium carbonate (Li2CO3) on the activity of adenyl cyclase in normal pig epidermis. Li2CO3 decreased the responsiveness of adenyl cyclase to stimulation by histamine, adenosine monophosphate (AMP) and epinephrine. This abnormality is similar but not identical to the previously described impaired responsiveness of adenyl cyclase to epinephrine and PGE2 in psoriatic plaques compared to normal adjacent skin. Involved and uninvolved skin from a psoriatic on lithium therapy demonstrated decreased responsiveness to in vitro stimulation by epinephrine, histamine and adenosine when compared to skin from psoriatics who were not on lithium therapy. These results are consistent with the observation that lithium therapy worsens psoriatic lesions.

Phosphorylation of epidermal keratins

When human and rat epidermis are exposed to 32P-orthophosphoric acid, labeled phosphate is incorporated into several proteins. The pattern of phosphorylation is identical whether the isotope is delivered in vivo or in vitro. The predominant phosphorylated proteins are insoluble in Tris-HCl buffer but soluble in SDS-beta-mercaptoethanol. They migrate in SDS-polyacrylamide gels with apparent molecular weights between 45,000 and 65,000. When analyzed by two-dimensional gel electrophoresis, the labeled phosphoproteins co-migrate with keratins isolated from human callus. Serine is the phosphate acceptor in these proteins. The pattern of phosphorylation of these SDS-beta-mercaptoethanol soluble epidermal proteins is not changed in basal cell carcinoma, icthyosis vulgaris, Kyrle's disease or Netherton's syndrome. The pattern is altered in psoriasis. Others have demonstrated that a 63,000 molecular weight protein is absent from active psoriatic lesions. We have found that a 63,000 molecular weight phosphoprotein is present in uninvolved skin but absent in the psoriatic plaques.

Effects of hydrocortisone on the adrenaline-adenylate cyclase system of the skin

Using pig skin slices, we investigated the effects of hydrocortisone on the adenylate cyclase system of the skin. In short-term experiments, hydrocortisone, when added singly or in combination with other stimulators of adenylate cyclase in the skin (adrenaline or histamine), had no effect on cyclic AMP accumulation. However, when skin slices were incubated with hydrocortisone for more than 6 h, the response to adrenaline differed, with a greater accumulation of cyclic AMP in the hydrocortisone-treated skin. This effect was seen at a concentration of more than I micrometer hydrocortisone and was most marked 48 h later, while responses to adrenaline in control skin gradually decreased and remained low. Histamine, which is another stimulator of adenylate cyclase of the skin, did not cause a greater cyclic AMP accumulation in response to this hydrocortisone treatment. There was no significant difference in either low Km or high Km cyclic AMP phosphodiesterase activities as a result of this hydrocortisone treatment. Hydrocortisone seems to act by protecting the adrenaline-adenylate cyclase system of the skin.

Metabolic aspects of psoriasis: the basis for specific therapy

Psoriasis, like diabetes, is a multifactorial genetic disease with complex interactions of deranged metabolism. Factors that affect epidermal differentiation and proliferation include cyclic nucleotide interactions, polyamine metabolism, cell surface--cytoskeleton interactions, and arachidonic acid--prostaglandin cascade. Evidence indicates that pharmacologic manipulation of the so-called critical metabolic systems not only may help us to understand the pathophysiology of psoriasis but also may yield improved treatments for the disease.

Epidermal thinning: evaluation of commercial corticosteroids

Epidermal thinning of mouse tail skin was compared for commercial preparations of clobetasol propionate (Dermovate), clobetasone butyrate (Eumovate), fluocinonide (Metosyn), and hydrocortisone butyrate (Locoid). The thickness measurements were ranked with those for hydrocortisone (1%), betamethasone valerate (Betnovate), triamcinolone acetonide (Ledercort), fluocinolone acetonide (Synlar), and prednisolone stearoylglycolate (Sinistrone) obtained in a previous study (Spearman and Jarrett, 1975). All steroids caused epidermal thinning, except clobetasone butyrate. Some cream and ointment vehicles were also assayed. Epidermal thickening was caused by the cream and ointment vehicles used for Eumovate and also by the cream employed for Locoid formulation.

Dermatologic manifestations of lithium: a review

This paper summarizes the major dermatologic and immunologic complications associated with lithium carbonate ingestion. This drug has demonstrated proven efficacy in the treatment of bipolar affective disorder. This fact, the authors believe, outweights its dermatologic complications, and only exacerbation of psoriasis warrants termination of therapy.

Multicenter trial of fluocinonide in an emollient cream base

Working independently, eight investigators evaluated the clinical effectiveness of fluocinonide 0.05% in a three-week double-blind paired comparison trial of 240 patients. Half the investigators compared fluocinonide emollient cream with betamethasone valerate 0.1% cream in the treatment of atopic dermatitis, while the remaining four compared the study drug with triamcinolone acetonide 0.1% cream in the treatment of psoriasis. Statistical analysis showed clinical responses favored fluocinonide p = 0.021 (Wilcoxon Signed Rank) for the atopic dermatitis group and p = 0.001 (Wilcoxon Signed Rank) for the psoriasis group.

Studies on 2', 3'-cyclic AMP 3'-phosphohydrolase in rabbit skin

Previous studies indicated that 2', 3'-cyclic AMP 3'-phosphohydrolase, an enzyme which splits the 3'-phosphate bond of the 2', 3'-cyclic AMP, is primarily confined to nervous tissue. The physiological function of this enzyme is still unknown. In the present study this enzyme was found to be active in various organs of rabbit, i.e. liver, kidney, heart and skin, although to a much lesser extent than in brain and sciatic nerve. The finding of this enzyme in the skin generated further studies to measure the enzyme activity in normal and diseased skin. Chemically induced (surfactant-treated) skin disorder was used as a model for the present study. Topical application of Polysorbate 85 resulted in a two fold increase of the enzyme activity in rabbit skin. The results suggest that this enzyme may have some role in the repair mechanisms, particularly in the regeneration of damaged membranes.

Enhanced chemotactic and phagocytic activities of leukocytes in psoriasis vulgaris

Leukocytes derived from the peripheral blood of psoriatic patients demonstrated an enhanced chemotactic response compared with leukocytes from healthy subjects. No significant difference was detected between the chemotactic response of leukocytes from patients with minimal or no skin involvement and those from patients with extensive lesions. Psoriatic leukocytes also had a significantly higher capacity to engulf 125I labeled Shigella flexneri than control leukocytes. It is postulated that a decrease in the cyclic AMP/cyclic GMP ratio in psoriatic leukocytes, similar to the imbalance of these 2 cyclic nucleotides found in the lesional epidermis of psoriasis, might be the cause of their enhanced chemotactic and phagocytic activities.

The effect of topical isoprenaline on psoriatic skin

Twelve patients with psoriasis were treated by the topical application of 0.1% isoprenaline sulphate ointment for 10 days. Topical white vaseline was used as a control in three patients with psoriasis. The mean glycogen level was found to be decreased significantly (from 120 +/- s.d. 40 to 58 +/- s.d. 26 mg/100 g of wet weight of involved skin) after topical application of 0.1 isoprenaline sulphate and the scaling also disappeared. Topical application of white vaseline did not produce any significant change in glycogen levels or scaling. The changes after isoprenaline application may have been due to an increase in the ratio of cyclic AMP/cyclic GMP which inhibited cell turnover and increased glycogenolysis.

[Skincycle of a new spontaneous mutant (Nackig) with abnormal hair keratinization in the mouse (author's transl)]

The pathomorphological and pathophysiological reactions of the first skincycle of the mutant (Ng) were histologically investigated. 1. During the hair growth disturbances as the result of imperfect keratinisation changes of the morphology and function of different skin areas could be observed. 2. The developments of abnormal thinner hair growth were correlated to hyperorthokeratotic, inter-respectively intrafollicular hyperplasia of the epidermis and to infraseboglandular hypoplasia of the follicles. 3. The hyper- and hypoplasia of the epidermis corresponded with a functional pseudohypo- and pseudohypertrophy of the cutis. 4. During the skincycle the perifollicular epithelium ranged from the inter- to intrafollicular skin areas. The inter- and intrafollicular epidermal sections varied simultaneously. 5. These results are important for the understanding of some pathomorphological and pathophysiological reactions of skin compartments of man.

Cyclic AMP accumulation in psoriatic skin: differential responses to histamine, AMP, and einephrine by the uninvolved and involved epidermis

Using the uninvolved and involved skin from psoriatic patients, we investigated the effects of histamine and AMP (or adenosine) in vitro on the intracellular cyclic AMP levels. Both agents activated adenylate cyclase of the uninvolved and involved resulting in the accumulation of cyclic AMP. Without a cyclic nucleotide phosphodiesterase (PDE) inhibitor, these responses were biphasic and the maximal accumulation was observed in 5 min. With the PDE inhibitor both responses were markedly potentiated and high levels of cyclic AMP were observed for more than 20 min. The response to histamine by the involved skin was much greater than that by the uninvolved. The degree of the response to adenosine was approximately equal. In accordance with our previous work, the response to epinephrine by the involved skin was much less than that by the uninvolved. Thus adenylate cyclases of involved skin from psoriatic patients exhibit a markedly diminished response to epinephrine while at the same time exhibiting a markedly enhanced response to histamine. This precludes the possibility that the unresponsiveness to epinephrine can be due to a generalized inability of the epidermal psoriatic plaque cell to make a functioning cell membrane.

The relationship between cyclic adenosine 3', 5' - monophosphate and biochemical events in rat skin after the induction of epidermal hyperplasia using hexadecane

Sequential changes in skin metabolism have been studied in a model system of epidermal hyperplasia and hyperkeratinization induced by the application of n-hexadecane to shaved rat skin. The epidermal accumulation of glycogen typical of the hyperplastic response has been correlated with an increase in glycogenesis and a decrease in glycogenolysis. DNA synthesis was increased by 6 h after the start of hexadecane treatment and reached a maximum after one day. The concentration of skin cyclic AMP fell immediately after hexadecane application and subsequently rose to give a prolonged increase. Use of the combined topical application of hexadecane and the anti-inflammatory drugs triamcinolone acetonide, hydrocortisone and indomethacin showed that the hexadecane-induced changes in DNA synthesis and glycogen metabolism were linked to the initial fall in cyclic AMP concentration. The significance of the biphasic change in cyclic AMP levels is discussed as a possible system of control for the development and maintenance of hyperplasia.

The expression of the gene asebia in the laboratory mouse. I. Epidermis and dermis

Mice homozygous for the asebia mutation (ab/ab), which have defective sebaceous glands, display abnormalities in several other aspects of the integument. Histological sections showed that hyperplasia of the cellular layers and the stratum corneum of the epidermis is apparent at birth and increases markedly with age. Enlarged intercellular spaces are also noted in the epidermis. The thicker dermal layer of the asebic mice is characterized by increased vascularity, increased cellularity and the abnormal morphology of a large proportion of the ‘fibroblast’ population. Electron microscopy demonstrated the many abnormalities in the dermal fibroblasts as well as large amounts of cellular debris in the surrounding matrix. Collagen and elastin show alterations at the light microscopic and ultrastructural levels. Many features of the asebic dermis resemble those found with mild inflammation and with the lysosomal storage diseases. Changes in the dermis of asebic foetuses were noted prior to epidermal alterations and may mediate the latter.