The enhanced monocyte and neutrophil chemotaxis in psoriasis is normalized after treatment with psoralens plus ultraviolet A and anthralin

Advances in the Application of Natural Products and the Novel Drug Delivery Systems for Psoriasis

Psoriasis, an incurable autoimmune skin disease, is one of the most common immune-mediated disorders. Presently, numerous clinical research studies are underway, and treatment options are available. However, these treatments focus on improving symptoms of the disease and fail to achieve a radical cure; they also have certain toxic side effects. In recent years, natural products have increasingly gained attention because of their high efficiency and low toxicity. Despite their obvious therapeutic effects, natural products’ biological activity was limited by their instability, poor solubility, and low bioavailability. Novel drug delivery systems, including liposomes, lipospheres, nanostructured lipid carriers, niosomes, nanoemulsions, nanospheres, microneedles, ethosomes, nanocrystals, and foams could potentially overcome the limitations of poor water solubility and permeability in traditional drug delivery systems. Thus, to achieve a therapeutic effect, the drug can reach the epidermis and dermis in psoriatic lesions to interact with the immune cells and cytokines.

Impairments in complement receptor- and Fc receptor-mediated functions in vivo in patients with psoriasis

The function of the fixed macrophage system in 18 psoriasis patients was evaluated by measuring the elimination rate of injected autologous erythrocytes coated with iC3b or IgG. The mean half-life of iC3b-coated erythrocytes was significantly prolonged in patients with psoriasis compared with healthy controls (4.7 +/- 0.8 vs 2.7 +/- 0.2 min, P = 0.01). There was also a decrease in the total number of cells eliminated from the circulation (2.5 +/- 0.2 x 10(8) vs 3.3 +/- 0.2 x 10(8), P = 0.01). There was an even more pronounced increase in the half-life of IgG-coated erythrocytes (85 +/- 18 vs 20 +/- 5 min, P < 0.001), with normal values in only 5 of 15 patients, and 4 of these 5 patients were receiving systemic treatment. The slow elimination was interpreted as being caused by primary or secondary defects in receptor function rather than by blocking of the receptors by immune complexes, since patients with psoriasis show normal levels of circulating immune complexes. Further studies are needed to elucidate the nature of these defects.

Extemporaneous prescribing (1)

An outline of the pharmacology of important components of extemporaneous prescriptions will be undertaken over four issues of the journal. Substances such as dithranol, salicylic acid and coal tar will be examined in some depth with regard to their mode of action, uses and side effects. In addition, examples of extemporaneous formulations containing these substances will be provided along with advice regarding their use. Substances such as sulphur, calamine, podophyllin and menthol will also be reviewed using the same format but in less detail. The articles are designed to provide practical knowledge in the area of extemporaneous prescribing. Complicated areas of pharmaceutical chemistry, unless relevant to the clinical setting, will not be discussed.

Inhibition of human monocyte functions by anthralin

Anthralin is a well-established and widely used compound for topical treatment of psoriasis. In recent years attention has been focused on the anti-inflammatory properties of anthralin, with particular reference to psoriasis. In this study the effect of anthralin on human monocyte chemotaxis, superoxide-anion generation, and enzyme degranulation, were investigated. For comparison, the effect of the clinically inactive anthralin derivative danthrone and the solvent (acetone) were also studied. The results show that anthralin potently inhibits stimulated human monocyte superoxide-anion generation and enzyme degranulation, with a half-maximal inhibitory concentration (IC50) of as low as 0.02 micrograms/ml. Chemotactic migration of monocytes, however, was only affected when very high doses of anthralin (10 micrograms/ml) were used for pretreatment of the cells. Danthrone, up to a concentration of 10 micrograms/ml, or acetone alone (0.1%, v/v), did not inhibit the monocyte functions tested. Our results indicate that anthralin at pharmacological concentrations is a potent and selective inhibitor of human monocyte pro-inflammatory activities, by inhibiting respiratory burst activity (e.g. superoxide-anion generation) and enzyme degranulation, without affecting chemotactic migration.

The antipsoriatic compound anthralin influences bioenergetic parameters and redox properties of energy transducing membranes

Bioenergetic parameters and redox properties of energy transducing membranes in rat liver mitochondria and cyanobacteria were investigated in the presence of the antipsoriatic compound anthralin (1,8-dihydroxy-9-anthrone). Transmembrane pH and electrical gradients were determined using electron paramagnetic resonance spectroscopy. In mitochondria, ubiquinones 9,10 and other redox components of the electron transport chain are reduced by anthralin; the proton motive force is increased. In the absence of ADP, anthralin slightly stimulates mitochondrial cyanide-insensitive oxygen consumption. It is suggested that increased cyanide-insensitive respiration is due to enhanced autoxidation of mitochondrial components and/or catalyzed oxidation of anthralin. In the presence of ADP mitochondrial respiration is decreased, and ATP synthesis is inhibited. Uncoupler-induced mitochondrial respiration is also decreased by anthralin, indicating inhibition of the electron transport chain. In the cyanobacterium Synechococcus PCC 6311 anthralin increases the pH gradient and decreases ATP levels. Thus, anthralin acts as an electron donor to membrane associated redox components and inhibits ATP synthesis in two different biologic systems. In human keratinocytes oxygen metabolism is influenced by anthralin in a similar pattern as in isolated mitochondria, and ATP content is decreased. Because anthralin reacts with redox components in different biologic membranes, alterations of subcellular/cellular redox status and energy metabolism might contribute significantly to its antiproliferative activity.

Polymorphonuclear leukocyte functions in psoriasis

Circulating polymorphonuclear leukocyte (CPMN) functions were studied in patients with widespread psoriasis as well as in persons with chronic alcoholic liver disease (CALD), paracoccidioidomycosis, diverse granulomatous diseases, and normal individuals. We were unable to find stimulation or increase in CPMN functions in patients with psoriasis compared to normal individuals. Leukocytes from individuals with CALD had a lowering of their metabolic activation, chemotaxis, random movement, and adherence. CPMNs from patients with paracoccidioidomycosis showed a significant deficiency in their ability to digest Paracoccidioides brasiliensis. Our results are against the concept that functions of circulating PMNs are stimulated in psoriatics.