Cyclic nucleotide levels in psoriatic and normal keratomed epidermis

Single-nucleotide polymorphisms as important risk factors of diabetes among Middle East population

Diabetes is a chronic metabolic disorder that leads to the dysfunction of various tissues and organs, including eyes, kidneys, and cardiovascular system. According to the World Health Organization, diabetes prevalence is 8.8% globally among whom about 90% of cases are type 2 diabetes. There are not any significant clinical manifestations in the primary stages of diabetes. Therefore, screening can be an efficient way to reduce the diabetic complications. Over the recent decades, the prevalence of diabetes has increased alarmingly among the Middle East population, which has imposed exorbitant costs on the health care system in this region. Given that the genetic changes are among the important risk factors associated with predisposing people to diabetes, we examined the role of single-nucleotide polymorphisms (SNPs) in the pathogenesis of diabetes among Middle East population. In the present review, we assessed the molecular pathology of diabetes in the Middle East population that paves the way for introducing an efficient SNP-based diagnostic panel for diabetes screening among the Middle East population. Since, the Middle East has a population of 370 million people; the current review can be a reliable model for the introduction of SNP-based diagnostic panels in other populations and countries around the world.

Sugar (sucrose) and fatty acid compounds with triglycerides on the treatment of wounds: experimental study in rats

BACKGROUND

In the last 10 years, the use of essential fatty acids (EFA) compounds for the treatment of wounds has increased in Brazil, while there has been reducing indication for the use of sugar.

OBJECTIVE

The aim of this study was to evaluate the response to saline, sugar and EFA on induced wounds in rats.

METHODS

A wound of 400 mm(2) was produced on the back of each Wistar rat. The rats were divided into three groups, each being treated with either saline, sugar or EFA. All the animals received a closed dressing on the wounds, changed daily. Measures were taken in four moments, and the values of wound area reduction by healing, cellular inflammatory response, collagen ordering and types I and III collagen density were assessed.

RESULTS

The wound healing was equal in all the three groups, but sugar promoted an inflammatory response modulation between the 7th and 14th days. On the 20th post-operative day, there were no differences between the three treated groups concerning types I and III collagen.

CONCLUSIONS

The wounds healed in the three groups. The sugar group promoted effective cellular inflammatory response modulation. There were no differences between all the treated groups regarding types I and III collagen at the end of this study.

High glucose inhibits human epidermal keratinocyte proliferation for cellular studies on diabetes mellitus

In order to more clarify the delayed wound healing in diabetes mellitus, we cultured the human epidermal keratinocytes in both 6 mM (control group) and 12 mM glucose (high-glucose group) of "complete" MCDB 153 medium. Hyperglycaemia slowed the rate of their proliferation and inhibited their DNA synthesis and the production of total proteins. By 1 month after primary seeding in high-glucose group, the cells ceased their proliferation, whereas the cells in control group grew for more than 40 days. Mean population doublings in high-glucose group was 5.27 (vs. 7.25 in control, P = 0.001), and mean population doubling time during 1 month in high glucose group was 5.43 days (vs. 3.65 days in control, P = 0.02). They indicate that prolonged exposure to high glucose decreases the replicative life span of human epidermal keratinocytes in vitro. Furthermore, analysis of fatty acid contents in membrane phospholipids with thin-layer and gas chromatography showed no difference between the cultured keratinocytes in both conditions. Immunocytochemical staining of glucose transporter 1 shows that 28.1% of cells in high-glucose group were almost twice positive of those in control group (13.2%, P = 0.008). The mechanism of the ill effects of high glucose on epidermal keratinocytes is not so far clear, but it indicates the possibility of any direct effect of hyperglycaemia on glucose metabolism without changing lipid metabolism on cell membrane. The high-glucose group presented in this report can be available as an in vitro valuable study model of skin epidermal condition on diabetes mellitus.

Retinoic acid stimulates essential fatty acid-supplemented human keratinocytes in culture

The effect of all-trans retinoic acid on the proliferation of essential fatty acid (EFA)-deficient and of EFA-supplemented adult human keratinocytes was investigated. EFA-deficient cell strains were supplied with one of four different fatty acid-supplemented media at the P0 to P1 passage. All-trans retinoic acid at 0.5 or 1.0 microM was added to the cultures at the P1 to P2 passage. At passage P3, and 3 and 7 d thereafter, the cell growth rate was determined. The fatty acid content of cultures grown in each medium was measured using gas chromatography. All the EFA media "normalized" the cellular fatty acid composition and drastically decreased the cell number and total DNA and protein of the cultures. All-trans retinoic acid at 1 microM prevented the loss of cell viability and growth usually associated with EFA supplementation but did not affect the control (EFA deficient) or 18:1 fatty acid-supplemented cultures. All-trans retinoic acid at 1 microM altered the fatty acid content of the EFA-supplemented cultures. A statistically significant increase in 14:0, 14:1, 16:1, 18:1, and 20:4 fatty acids occurred, whereas the amounts of 18:0 and 18:2 fatty acids decreased. The largest changes were in 16:1 fatty acid (8-14%) and 18:2 fatty acid (12-5%). All-trans retinoic acid at 0.5 microM also affected both cell growth and fatty acid composition without induction of the CRABP II message. These studies demonstrate that all-trans retinoic acid stimulates the growth of EFA-supplemented keratinocyte cultures while also altering the fatty acid composition of the cells.

Development of new wound dressing composed of spongy collagen sheet containing dibutyryl cyclic AMP

Although cyclic AMP has been considered to regulate cell proliferation, the mechanism of this function is largely unknown. Recent studies suggest that cyclic AMP promotes the proliferation of skin cells in a dose-dependent manner. An ointment containing dibutyryl cyclic AMP has been used in the treatment of skin ulcers and found to be effective in promoting tissue repair. To search more efficacious wound management, the authors developed a new wound dressing composed of a spongy atelo-collagen sheet containing dibutyryl cyclic AMP. This wound dressing was evaluated in two types of animal tests. One is the application of the wound dressing to a full-thickness skin defect in order to evaluate the granulation tissue formation and the wound size reduction. The wound dressing was found to promote the granulation tissue formation and naturally reduce the wound size. The other test was the application of the wound dressing to the full-thickness skin defect, leaving behind a skin island in a central portion, in order to evaluate the epithelialization. This skin island left in a full-thickness skin defect was extremely enlarged. The enlargement of the skin island seems to be related to the epithelialization from the margin of the skin island as well as by the expansion of a skin island induced by contraction of the developed granulation tissue in the surrounding wound area. These results suggest that an atelo-collagen spongy sheet containing dibutyryl cyclic AMP is effective in promoting the granulation tissue formation and epithelialization.

Investigations of the 'active' edge of plaque psoriasis: vascular proliferation precedes changes in epidermal keratin

We have investigated markers of epidermal proliferation and differentiation in terms of keratin expression, the morphology of the cutaneous vasculature, and numbers of cutaneous mast cells, in patients with chronic plaque psoriasis. Using the phenomenon of the 'active edge', we have studied these features in the psoriatic plaque itself, and in the clinically normal active and inactive edges of the same plaque. Our results confirm the anticipated changes in keratin profiles, mast cell numbers and psoriatic morphology of the vasculature within the plaque itself. They further indicate that the vascular changes precede the epidermal and mast cell features at the active edge, and that the inactive edge is inactive for all of these variables. Mediators responsible for the vascular proliferation and elongation must be present in increased amounts at the active edge when compared with the inactive, and include locally produced and circulating factors.

Normalization of essential-fatty-acid-deficient keratinocytes requires palmitic acid

Cultured adult human keratinocytes show accelerated growth rates in medium that is essential fatty acid deficient. The cells also show decreased amounts of the essential fatty acids 18:2, 20:3, and 20:4 and contain increased amounts of the monounsaturated fatty acids 16:1 and 18:1. These lower levels of polyunsaturated fatty acids were only partially restored by supplementing the medium with 18:2 and 20:4 fatty acid. The addition of the non-essential fatty acid 16:0 (5 microM), along with the essential fatty acids, resulted in the successful normalization of the major fatty acids in the deficient keratinocytes. Normalized cells showed a constant total fatty acid/mg of protein in the phospholipid fraction, as the total cell fatty acid content per cell increased with augmenting fatty acid supplementation. Supplementation of the medium with 16:0 and essential fatty acids decreased the growth and passage potential of the cells. Use of 18:1 in lieu of 18:2 fatty acid yielded essential-fatty-acid-deficient keratinocyte growth values. Likewise the least supplemented medium (5 microM 18:2 + 5 microM 16:0) also gave the accelerated cell growth rates. This study shows that manipulation of the essential fatty acid levels, if accompanied by 5 microM 16:0 in the growth medium, alters the growth properties of adult human primary keratinocytes.

The regulatory subunit of cAMP-dependent protein kinase as a target for chemotherapy of cancer and other cellular dysfunctional-related diseases

Three separate experimental approaches, using site-selective cAMP analogs, antisense strategy and retroviral vector-mediated gene transfer, have provided evidence that two isoforms, the RI- and RII-regulatory subunits of cAMP-dependent protein kinase, have opposite roles in cell growth and differentiation; RI being growth stimulatory while RII is a growth-inhibitory and differentiation-inducing protein. As RI expression is enhanced during chemical or viral carcinogenesis, in human cancer cell lines and in primary human tumors, it is a target for cancer diagnosis and therapy. 8-Cl-cAMP and RI antisense oligodeoxynucleotide, those that effectively down-regulate RI alpha and up-regulate RII beta, provide new approaches toward the treatment of cancer. This approach to modulation of RI vs RII cAMP transducers may also be beneficial toward therapy of endocrine or cellular dysfunction-related diseases where abnormal signal transduction of cAMP is critically involved.

In vitro model of essential fatty acid deficiency

The polyunsaturated fatty acids linoleic acid (18:2, n-6) and arachidonic acid (20:4, n-6) are essential for normal skin function and structure, both as eicosanoid precursors and as components of lipids forming cell membranes. Adult human keratinocytes grow optimally in serum-free medium (MCDB 153) that contains no fatty acids. These keratinocytes expand rapidly and produce normal epidermis upon in vivo grafting. Analysis of lipid extracts of epidermis and of cultured keratinocytes was done to determine the fatty acid composition of cells grown in essential fatty acid (EFA)-deficient medium. Gas chromatography and high-performance liquid chromatography analyses were done of the fatty acids in the entire cell and in a thin-layer chromatography separated fraction containing those lipids that form cellular membranes. Comparison of snap-frozen epidermis and epidermal basal cell suspensions to passage 1 to 4 cultures shows that the cells are in an extreme essential fatty acid-deficient state by the first passage. The amount of the saturated fatty acids 16:0, 18:0, and 14:0 is unchanged by culture. The polyunsaturated fatty acids are found to be significantly decreased, the cells balancing their lack with a significant increase in the relative abundance of the monounsaturated fatty acids, 18:1 and 16:1. Greater than 85-90% of the fatty acids was found in lipids associated with membranes and no unusual fatty acids were detected. Because the serum-free medium is fatty acid free and the cells cannot synthesize essential fatty acids, the rapid division of the cells results in the predominance of an extreme EFA-deficient cell type. The essential fatty acid-deficient keratinocyte is an excellent adult, normal epidermal cell model that can be used to study EFA deficiency and the effect of the eicosanoid and fatty acids on cell function and structure.

Photosensitizing action of furocoumarins on membrane components and consequent intracellular events

The photodamage induced in membrane components by furocoumarins is reviewed. The oxygen-dependent photoreactions between furocoumarins and cell membrane constituents lead mainly to lipid peroxidation and the formation of cross-linking in ghost proteins, whereas the oxygen-independent photoreactions lead essentially to a C4 cycloaddition between the furocoumarin and the unsaturated fatty acids. In the latter, cycloadducts are formed between the 3,4 double bond of the furocoumarin and the olefinic double bond of the unsaturated fatty acid. The stereochemical structures of these cycloadducts and the reaction mechanism of the cycloaddition are discussed. Finally, the modulation of several membrane systems by furocoumarins and the consequent intracellular events are reviewed.

Beta-adrenergic stimulation of cyclic AMP is defective in cultured dermal fibroblasts of psoriatic subjects

Epidermal cells from psoriatic lesions demonstrate a very low cAMP response to beta-adrenergic stimuli. We have shown that a similar abnormality occurs in dermal fibroblasts from affected areas of skin. The cells, after 5-12 passages in tissue culture, had a much reduced response to 10(-8) M and 10(-6) M isoproterenol when compared with fibroblasts from control subjects. The abnormality was not abolished by the addition of the phosphodiesterase inhibitor, 3-isobutyl-I-methylxanthine. Other putative agonists tested were vasoactive intestinal peptide and peptide histidine methionine. Neither of these had an effect on dermal fibroblasts from either normal controls or from lesions of psoriasis.

Retinoid treatment of human psoriatic fibroblasts induces an increase in cyclic AMP-dependent protein kinase activity

We recently showed a deficiency of cyclic AMP (cAMP)-dependent protein kinases in psoriatic cells. In this work the effects of retinoids on cAMP-dependent protein kinases of fibroblasts from 7 normal subjects and 7 psoriatic patients were studied. The levels of RI and RII (two forms of the cAMP-dependent protein kinases) present in control and retinoic acid-treated cells were quantitated by photoaffinity labeling with [8-azido-32P]cAMP. In psoriatic fibroblasts the levels of RII are decreased or undetectable compared with those of normal fibroblasts both in the cytosolic and membrane fractions. The amount of RI was normal in the cytosol of fibroblasts of 5 out of 7 patients and decreased in 2 patients. Membrane-associated levels of RI were decreased in 5 patients and normal in 2 patients. Retinoic acid treatment induces an increase in the amount of RI and RII regulatory subunits when they are deficient in the cytosolic and membrane fractions of psoriatic fibroblasts. Retinoic acid had no effect on RI and RII in normal fibroblasts. In addition, with in vitro retinoic acid treatment the cAMP-dependent protein kinase activity, measured in the fibroblasts of 4 psoriatic patients, was increased in the cytosol in 2 patients and in the membranes in all 4 patients. In these studies, comparable results were obtained with fibroblasts cultured from involved and uninvolved skin. This in vitro effect of retinoids on cAMP-dependent protein kinases in psoriatic fibroblasts may help to explain some of the in vivo therapeutic effects of retinoids.

An investigation of the ability of antipsoriatic drugs to inhibit calmodulin activity: a possible mode of action of dithranol (anthralin)

Epidermal calmodulin (CaM) has been reported to be elevated in psoriasis and to decrease following clearance of psoriasis with treatment. We set out to investigate whether any of the principle drugs used in the treatment of psoriasis had inherent CaM antagonist activity. Utilizing a CaM-activated phosphodiesterase we have demonstrated that even at very high concentrations, the systemic drugs etretinate, methotrexate, and 8-methoxypsoralen, and the topical agents hydrocortisone and crude coal tar showed minimal CaM inhibitory activity. Dithranol (anthralin), however, whether freshly prepared or oxidized, produced substantial inhibition of CaM activity and was demonstrated to be a potent competitive antagonist of CaM, suggesting another possible therapeutic mode of action of dithranol in psoriasis.

Deficiency of cyclic AMP-dependent protein kinases in human psoriasis

To determine possible differences in the cyclic AMP-dependent protein kinases of normal and psoriatic human fibroblasts, the levels of the regulatory subunits (RI and RII, respectively) of protein kinase I and protein kinase II were quantitated by photoaffinity labeling with 8-azido[32P]cAMP. The level of RII was significantly decreased, or was undetectable, in cytosol prepared from fibroblasts from five psoriatic subjects when compared to RII levels found with normal human fibroblasts. The level of cytosolic RI was decreased in fibroblasts from four psoriatic patients and was within the normal range for one diseased patient when compared to RI levels in normal human fibroblasts. The elution profile from a DEAE-cellulose column of protein kinase activity in the soluble fraction from two psoriatic patients also showed a decrease in type I kinase activity and the complete absence of type II kinase activity. Other results indicate that the level of RI in erythrocyte membranes from psoriatic subjects is significantly decreased when compared to that of erythrocyte membranes from eight normal subjects. A significant correlation (P less than 0.001) was observed between the severity of the cutaneous manifestation of the disease and the level of RI in psoriatic erythrocyte membranes. The changes noted in the levels of RI and RII in cell types other than those thought to be specifically involved in the proliferative epidermis disorder of the disease suggest a general protein kinase deficiency.

Altered [125I]epidermal growth factor binding and receptor distribution in psoriasis

Stimulation of growth and differentiation of human epidermis by epidermal growth factor (EGF) is mediated by its binding to specific receptors. Whether EGF receptors primarily mediate cell division or differentiation in hyperproliferative disease such as psoriasis vulgaris is unclear. To study the pathogenesis of psoriasis, 4-mm2 punch biopsy specimens of normal, uninvolved, and involved psoriatic skin were assayed for EGF receptors by autoradiographic, immunohistochemical, and biochemical methods. Using autoradiographic and immunohistochemical methods, basal keratinocytes were found to contain the greatest number of EGF binding sites and immunoreactive receptors as compared to the upper layers of the epidermis in both normal epidermis and psoriatic skin. No EGF receptor differences between normal and psoriatic epidermis were observed in this layer. In the upper layers of the epidermis, a 2-fold increase in EGF binding capacity was observed in psoriatic skin as compared with normal thin or thick skin. Biochemical methods indicated that [125I]EGF binding was increased in psoriatic epidermis as compared with similar thickness normal epidermis when measured on a protein basis. Epidermal growth factor was shown to increase phosphorylation of the EGF receptor in skin. EGF receptors retained in the nonmitotic stratum spinosum and parakeratotic stratum corneum may reflect the incomplete, abnormal differentiation that occurs in active psoriatic lesions. Alternatively, retained EGF receptors may play a direct role in inhibiting cellular differentiation in the suprabasal layers.

"Ischemic" rise of epidermal cyclic AMP is a beta-adrenergic adenylate cyclase-dependent process

The endogenous level of epidermal cyclic AMP does not remain constant but increases rapidly and transiently after removal of the tissue; this is known as the "ischemia" effect. UVB-irradiated epidermis which shows increased beta-adrenergic response revealed an increased ischemia effect, while psoriatic involved epidermis which shows decreased beta-adrenergic response revealed a decreased ischemia effect. Because of the similar rise-and-fall pattern between the ischemia effect and the beta-adrenergic response, the mechanism of the ischemia effect was investigated, especially in terms of the beta-adrenergic relationship. The ischemic rise of epidermal cyclic AMP was well preserved after 6 h pretreatment at 4 degrees C, and, following the pretreatment, the skin markedly increased its cyclic AMP level by the 37 degrees C treatment with 1 mM isobutylmethyl xanthine. The addition of propranolol or cimetidine at the time of 37 degrees C treatment (following the 4 degrees C pretreatment) had no effect on the ischemia effect; both skin groups markedly increased their cyclic AMP levels to an extent similar to that of the control skin. However, the addition of propranolol at the time of both preincubation (at 4 degrees C) and incubation (at 37 degrees C) markedly decreased the ischemic rise of cyclic AMP. Similar treatment by cimetidine had no effect on the ischemia effect. There was no significant difference in cyclic AMP phosphodiesterase activities among skin groups by propranolol or cimetidine pretreatment. These results indicate that the so-called ischemic rise of epidermal cyclic AMP is actually the beta-adrenergic adenylate cyclase-dependent process. Our results also indicate that the magnitude of the "ischemic" rise of cyclic AMP is generally parallel to the beta-adrenergic responsiveness of epidermis.

Metabolism of linoleic acid and other essential fatty acids in the epidermis of the rat

Essential fatty acids are absolutely necessary for maintaining the proper condition of the water barrier (stratum compactum) in the skin. Even direct topical application of linoleic acid or any other Z,Z-(n-6, n-9)-fatty acid to the skin restores the barrier in essential fatty acid-deficient animals. In order to investigate the mechanism by which these polyunsaturated fatty acids exert their activity, radioactively labelled fatty acids were applied to the skin of the live animal and the epidermal lipids were analysed after 1-4 days. Much radioactivity was incorporated into two peculiar lipids, viz. acyl ceramide and acyl acid, which are characteristic of the barrier, in which linoleate was esterified to the end-position of very-long-chain (C30-34) unsaturated omega-hydroxy fatty acids. Strong evidence was obtained which showed that these lipids carry linoleate into the barrier layer where it is converted, probably by lipoxygenase(s), into a series of peroxidated lipids. The lipoxygenase inhibitor, eicosatetraynoic acid, prevents both oxygenation of the polyunsaturated fatty acid and the formation of a healthy skin. This peroxidation may supply the mediators which induce the proper differentiation of the epidermal cells into an effective stratum compactum and a horny layer.

Magnitude of ornithine decarboxylase induction by epidermal mitogens: effect of the assay technique

The polyamines, putrescine, spermidine and spermine, as well as ornithine decarboxylase (ODC), the rate-limiting enzyme of polyamine biosynthesis, are increased in the blood, urine and skin of psoriasis patients. A study of the association between stimulated epidermal cell proliferation and induction of ODC activity was done using both an intact, living cell ODC assay and the routinely used homogenized cell supernate assay. 10(-6) to 10(-8) mol/l of the tumor promoter, tetradecanoyl phorbol acetate (TPA), 10(-3) mol/l 8-BrcAMP, 10(-6) mol/l cholera toxin and 10(-3) mol/l MIX, which are epidermal cell mitogens, were used to stimulate basal cells in short-term suspension cultures, freshly plated monolayers, or up to 8-day-old cultures. The results showed that the ODC enzyme must be assayed in supernates from disrupted epidermal cells in order for significant ODC induction by hyperplastic agents to be observed.

Immunological aspects of psoriasis. VI. Impairment of isoprenaline and theophylline-induced inhibition of mitogen responsiveness

Pharmacological abnormalities occur in the psoriatic epidermis, and if similar abnormalities occur in the peripheral blood mononuclear cells they could impair the immune responses in psoriasis. In a paired control study, we have tested the capacity of histamine, isoprenaline and theophylline (10(-5) and 10(-7) M) to inhibit the mitogen responsiveness of blood mononuclear cells from normal and psoriatic subjects, using phytohaemagglutinin and concanavalin A. In the normal controls, mitogen responsiveness was inhibited by all three pharmacological agents by about 30 to 50%. In cells from psoriatic patients, the response in the presence of histamine was inhibited (as in the controls), but isoprenaline caused no inhibition, and theophylline paradoxically increased the mitogenic responses. These results suggest there is a defect in the pharmacological response of the blood mononuclear cells in psoriasis.

Effects of the anti-inflammatory agents indomethacin, metiamide and acetylsalicylic acid on the induction of hyperplasia in hamster cheek-pouch epithelium and ear epidermis

Previous studies have shown that agents such as indomethacin and hydrocortisone act to reduce the level of epidermal hyperplasia produced by various chemical, but little information is available about the effects of such anti-inflammatory agents on the induction of hyperplasia in oral mucosa. Hamster cheek-pouch epithelium and ear epidermis were treated with indomethacin, metiamide and acetylsalicylic acid prior to treatment with turpentine, podophyllin or TPA. The levels of hyperplasia induced were monitored by rates of epithelial glycolysis, protein synthesis and mitosis. The response of the metabolic assays to epinephrine was also examined. Alone, turpentine, podophyllin and TPA each caused a 3-5 fold increase in the metabolic assays and loss of the normal tissue response to epinephrine. Tissues pretreated with indomethacin showed significant reductions in the levels of hyperplasia produced and they retained a normal response to epinephrine. No reduction in hyperplasia was observed following pretreatment with acetylsalicylic acid, an alternative inhibitor or prostaglandin synthesis or with metiamide, a histamine blocker. The results indicate that the production of epithelial hyperplasia by turpentine, podophyllin and TPA can be inhibited by indomethacin.

Biologically active calmodulin levels are elevated in both involved and uninvolved epidermis in psoriasis

The aim of this study was to determine whether levels of biologically active calmodulin are elevated in both lesional and uninvolved epidermis in psoriasis. Epidermal shave biopsies were obtained from normal controls and from both psoriatic plaques and nonlesional psoriatic skin. Following determination of the protein content, the calmodulin activity of the homogenized samples was then measured using a calmodulin-sensitive phosphodiesterase enzyme bioassay. In normal skin, calmodulin activity was 1.29 +/- 0.35 micrograms calmodulin mg-1 epidermal protein (mean +/- SEM, n = 12 volunteers) compared to 7.88 +/- 1.59 micrograms calmodulin mg-1 epidermal protein for plaque (n = 16 patients) and 10.19 +/- 2.35 micrograms calmodulin mg-1 epidermal protein for the uninvolved skin of 12 of these patients. The levels of biologically active calmodulin were therefore elevated in both plaque and uninvolved epidermis of patients with psoriasis compared to epidermis from normal volunteers. These results suggest that an abnormality in the regulation of calmodulin activity may be involved in the pathogenesis of psoriasis.

The usefulness of reflectance spectrophotometric measurements during psoralens and ultraviolet A therapy for psoriasis

Reflectance spectrophotometry was used to obtain indices of the hemoglobin and melanin content of psoriatic lesions and adjacent clinically normal skin in thirteen patients undergoing photochemotherapy. The pretreatment lesional hemoglobin index was 2.8 times greater than that of adjacent uninvolved skin. With therapy, this index decreased rapidly initially, and during the second or third week approached that of the uninvolved skin. The ratio of lesional and uninvolved skin hemoglobin indices decreased to approximately 1.3, and continuation of PUVA treatment failed to reduce it further. Termination of treatment at this stage, which occurs before clinical resolution, resulted in subsequent clearance of psoriasis. The decrease in the lesional hemoglobin index and the clearance time appeared to be dose-dependent, and, indeed, a more aggressive regimen resulted in approximately 50% reduction in both the number of treatments and the cumulative dose required to achieve a stable hemoglobin index ratio and subsequent clinical clearance.

Polymorphonuclear leukocyte function in psoriasis: chemotaxis, chemokinesis, beta-adrenergic receptors, and proteolytic enzymes of polymorphonuclear leukocytes in the peripheral blood from psoriatic patients

Psoriatic patients, particularly those with psoriatic arthritis, have neutrophilic and eosinophilic leukocytosis. Isolated polymorphonuclear leukocytes (PMNLs) from psoriatic patients have normal concentrations of proteolytic enzymes and they have beta-adrenergic receptors of normal density and affinity. PMNLs from psoriatic patients responded normally to the synthetic chemotactic peptide, f-Met-Leu-Phe (formyl-methionine-leucine-phenylalanine). The chemotactic activities of sera from psoriatic patients were similar to those of normal sera. Sera from psoriatic patients enhanced chemokinesis of PMNLs more than normal control sera at a final concentration of 1%; no difference in chemokinetic response between psoriatic and normal sera was found at serum concentrations greater than 2.5%. This study suggests that the peripheral PMNLs from psoriatic patients are normal, but the sera of psoriatic patients has more chemokinetic activity for PMNLs than does normal serum.

Altered erythrocyte membrane phosphorylation in psoriasis

Autophosphorylation by [gamma-32P]ATP of erythrocyte membranes from controls, psoriatic patients and patients with skin disorders other than psoriasis was compared by polyacrylamide gel electrophoresis. Compared with controls, membranes from psoriatic patients showed significantly less 32P incorporation in the band 2 region (nomenclature of Fairbanks et al., 1971). In addition, psoriasis and some of the other skin diseases examined displayed decreased phosphorylation in the region of bands 2.9-3 and 4.5-4.8. A new polypeptide band in the 18-20,000 dalton region was also observed in the diseases examined. Altered epidermal plasma membranes have been implicated in the pathogenesis of psoriasis, and our findings suggest the defective plasma membranes may be a generalized phenomenon in this disorder.

Cyclic AMP, glucocorticoid, and retinoid modulation of in vitro keratinocyte growth

The hypothesis that an imbalanced cyclic AMP and cyclic GMP ratio was central to the cutaneous expression of psoriasis prompted the design of a series of in vitro experiments. The aim of these studies was to describe the functional effects of increased intracellular cyclic AMP and of drugs therapeutic in psoriasis on epidermal keratinocyte growth. Epidermal basal cells trypsinized from neonatal mouse and adult and neonatal human skin were grown on plastic or on gelled collagen surfaces. These were used to study the effect of cyclic AMP analogues and cholera toxin (an irreversible stimulator of cyclic AMP synthesis) on keratinocyte growth. Greatly increased intracellular cyclic AMP levels, that is, 60-fold to 70-fold, stimulated neonatal mouse keratinocyte proliferation and differentiation; these same doses were cytotoxic to both neonatal and adult human cells. However, modest increases in intracellular cyclic AMP did stimulate adult human keratinocyte proliferation. The glucocorticoid triamcinolone acetonide inhibited neonatal mouse keratinocyte proliferation for approximately 1 week; the cells then became refractory to the triamcinolone acetonide effect. Triamcinolone acetonide did not apparently act through cyclic AMP-mediated events. In fact, this glucocorticoid inhibited cyclic AMP-stimulated epidermal keratinocyte proliferation. Likewise, vitamin A analogues, including the psoriasis therapy drug Ro 10-9359 inhibited neonatal mouse keratinocyte proliferation and specific differentiation events; the retinoids therapeutic in psoriasis apparently did not act via cyclic AMP-mediated events and inhibited cyclic AMP-stimulated functions. Our results indicated that cyclic AMP is a mitogenic signal for epidermal keratinocytes. This cyclic nucleotide may be important in regulating epidermal hyperproliferation. A central role for cyclic AMP in the cutaneous expression of psoriasis, however, is yet to be proven.

Effect of beta-adrenergic receptor blockade or refractoriness induced by isoproterenol on growth of keratinocytes in vitro

Almost complete suppression of beta-adrenergic sensitivity of adenylate cyclase was produced in keratinocytes growing on collagen gels either by induction of refractoriness by isoproterenol or by receptor blockade by propranolol, these drugs being introduced 3 days post-plating and continuously thereafter. Neither of these two manoeuvres affected growth of the keratinocytes. Despite this suppression, basal levels of cyclic AMP never fall below the levels observed in untreated cultures. On the other hand, growth inhibition is observed if isoproterenol or propranolol is added on plating. When keratinocytes are seeded on 3T3 fibroblast feeder layers, isoproterenol enhances colony growth, as reported elsewhere, indicating that the effects of isoproterenol are therefore modulated by the culture surface. In either of these in vitro model systems studied (collagen or feeder layers), no mechanism was obvious that would account for propranolol-induced psoriasiform lesions observed in vivo.

The effects of alpha and beta adrenergic agonists and cyclic adenosine 3':5'-monophosphate on epidermal metabolism

Continuously regenerating stratified squamous epithelia form an interesting model for examining mechanisms controlling the balance between rates of cell formation and cell maturation and death. In vitro assays of rates of glycolysis and amino acid incorporation of epidermal sheets free from dermal contamination were used to examine rates of metabolism in both normal and hyperplastic epidermis after treatment with various adrenergic agonists and cAMP. Epinephrine and isoproterenol over the concentration range of 1 x 10(-9) to 1 x 10(-5) M depressed the rates of glycolysis and amino acid incorporation in normal epidermis. Dibutyryl cyclic AMP produced a 73 to 78% depression in metabolic activity and its action was enhanced by the addition of theophylline. The alpha adrenergic agonist norepinephrine produced similar reductions. When epidermal samples were treated with hexadecane to induce a mild hyperplasia, depressant effects of isoproterenol and epinephrine were lost, but dibutyryl cyclic AMP and norepinephrine still reduced metabolic activity. The results suggest that adrenergic agents and their putative second messenger cAMP cause reductions in epidermal metabolic activity, an effect similar to their effects on cell proliferation, and that increased rates of proliferation are associated with loss of beta adrenergic responsiveness of the epidermis.

Enhanced monocyte and neutrophil cytotoxicity and normal cyclic nucleotide levels in severe psoriasis

Eighteen patients with active psoriasis were investigated for antibody-dependent cell-mediated cytotoxicity (ADCC) mediated by monocytes and neutrophil leukocytes. Patients with extensive psoriatic lesions showed increased ADCC whereas patients with minimal psoriasis had normal monocyte and neutrophil function. After clinical remission the ADCC became normal. No stimulatory factors in psoriatic serum could be demonstrated. The increased monocyte and neutrophil cytotoxicity in severe psoriasis is not explained by altered cyclic nucleotide levels as cAMP and cGMP levels were normal in psoriatic monocytes and neutrophils showing both increased and normal ADCC. Our results indicate that increased ADCC is secondary to the psoriatic activity.

Cyclic GMP metabolism in psoriasis: increased activity of soluble epidermal cyclic GMP phosphodiesterase and its modulation by calcium

Soluble cyclic GMP-phosphodiesterase was measured in normal and psoriatic epidermis. The specific activity of the enzyme was increased almost four-fold in involved compared with normal epidermis, and two- to three-fold in involved compared with uninvolved epidermis. The enzyme activity from all three sources was inhibited by 40-50% by ethylene glycol tetraacetic acid (EGTA). These results indicate that in addition to the reported enhanced capacity of psoriatic epidermis to generate cGMP, it has an increased ability to hydrolyse this nucleotide, although to a lesser degree than the augmentation found in soluble guanylate activity from psoriatic epidermis. These observations are compatible with the elevated steady-state levels of this nucleotide observed in the involved epidermis of psoriasis.

Epidermal cyclic GMP is increased in psoriasis lesions

Cyclic GMP levels in epidermis of normal subjects and of psoriatic patients were measured with a highly sensitive radioimmunoassay method. Technical improvements for the assay are 2-fold: (1) skin samples were frozen in vivo before biopsy and local injection of any anesthetic was avoided to overcome ischemia effect which could lower cyclic GMP artificially; (2) epidermis was microdissected to avoid contamination of dermis and keratin layers. The results show that on a per mg tissue dry weight basis the cyclic GMP levels are about 200 fmol in the involved lesional epidermis and 70 fmol in the uninvolved or normal epidermis. Similarly increases in the cyclic GMP levels in the lesional epidermis are observed when the data are expressed either on a DNA or protein basis. The cyclic GMP level in normal epidermis from nonpsoriatic subjects is the same as that in the uninvolved epidermis of psoriasis patients.

Normal and psoriatic keratinocytes and fibroblasts compared in culture

The ability of psoriatic fibroblasts to stimulate growth of epidermal cells was studied by comparing the capacity of murine 3T3 cells, normal fibroblasts and psoriatic fibroblasts to act as feeder layers for cultured normal human keratinocytes. 3T3 cells consistently gave shorter times to confluency than normal or psoriatic cells which were about the same. The SDS polyacrylamide gel electrophoretic pattern of the fibrous protein was identical irrespective of the feeder layer use. Psoriatic epidermal cells could be grown from single cell suspensions by using 10(-9) M cholera toxin in the medium. The cultured psoriatic keratinocytes grew identically to normal cells and made the same fibrous protein. The psoriatic keratinocytes also grew better on 3T3 cells than normal or psoriatic fibroblasts.

Effect of phorbol ester application and other mitogenic treatments on 3',5'-cyclic-nucleotide phosphodiesterase activity in mouse epidermis in vivo

The effects of phorbol ester application and of other mitogenic treatments on the activity of 3',5'-cyclic-nucleotide phosphodiesterase were investigated in dorsal mouse epidermis in vivo. Local treatment with either the weak tumor promoter phorbol 12,13-dibenzoate or the strong promoter 12-O-tetradecanoylphorbol 13-acetate (TPA) increased the activity of the high affinity enzyme (Km = 4 microM). The enzymic changes began within the first hour after application, and lasted for about 5 days. maximal stimulations of approximately 300--400% were reached after 3--6 h with TPA application, whereas with phorbol dibenzoate the maximum could only be reached after 1--2 days. TPA stimulation of the enzyme depended on doses within the range of 0.2 to 20 nmol and could be completely prevented by cycloheximide, but not by 5-azacytidine, actinomycin D, 5,8,11,14-eicosatetraynoic acid or indomethacin. No evidence could be found for cAMP participation in enzyme induction. An increase in enzyme activity could also be observed after other mitogenic treatments such as local application of the weakly promoting phorbol esters C14:4-phorbol acetate ("Ti8") and 4.O-methyl-TPA, or of the non-promoting divalent cation ionophore A 23187, as well as after treatment with a depilatory cream. Skin massage or removal of the horny layer, which also stimulate mitosis, did not evoke a significant increase in enzyme activity. No apparent correlation exists between the hyperplasiogenic and tumor-promoting effectiveness of a manipulation and its effect on epidermal 3',5'-cyclic-nucleotide phosphodiesterase.

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.

The effect of steroid and dithranol therapy on cyclic nucleotides in psoriatic epidermis

Absolute values of both cAMP and cGMP leves were measured in the involved and uninvolved skin of psoriatic patients, and also the effect of topical therapy on these levels in the involved skin was studied. The mean cGMP level in the untreated psoriatic plaque was increased by 300% compared to the non-involved skin (which did not differ from normal skin), but no significant difference in cAMP levels was found. Epidermal stripping of uninvolved skin, which stimulates cell proliferation, did not change the cGMP level. Treatment of the psoriasis with dithranol caused the cGMP levels to return to normal, but a potent topical glucocorticoid, in contrast, produced no such decrease. This may imply that the two drugs act at different levels in suppressing cell replication, and dithranol may be a useful tool for the further investigation of cyclic nucleotide metabolism.

Cyclic GMP metabolism in psoriasis: activation of soluble epidermal guanylate cyclase by arachidonic acid and 12-hydroxy-5,8,10,14-eicosatetraenoic acid

Soluble guanylate cyclase activity was measured in normal and psoriatic human epidermis. The specific activity of guanylate cyclase was determined to be increased 10-fold and 3-fold in involved and uninvolved epidermis of psoriatics, respectively, compared to normal epidermis. Arachidonic acid (5 to 100 micrometers) or 12-hydroxy-5,8,10,14-eicosatetraenoic acid (HETE) (5 to 50 micrometers) stimulated guanylate cyclase activity from involved epidermis 2- to 3-fold and from uninvolved epidermis up to 2-fold, but these fatty acids had no effect on the activity of this cyclase from normal epidermis. These results indicate that there is an increase in the cGMP biosynthetic capacity of involved epidermis from psoriatics that derives from a markedly increased specific activity of guanylate cyclase and an alteration in a property of this enzyme activity which renders it responsive to fatty acids reported to accumulate in this lesion. These observations are consistent with the report that an elevated steady-state level of cGMP is one of the consequences of the strikingly altered metabolism of cGMP in psoriatic epidermis.