The phosphodiesterase (PDE) 4 is the predominant cyclic AMP degrading enzyme in a variety of inflammatory cells including eosinophils, neutrophils, macrophages, T cells and monocytes. In addition, this enzyme is expressed in non-immune cells such as keratinocytes and fibroblasts. Highly selective PDE4 inhibitors are currently under evaluation for the treatment of asthma and/or chronic obstructive pulmonary disease. Due to the broad anti-inflammatory/immunomodulatory action of PDE4 inhibitors, it has been proposed that PDE4 inhibitors might also be efficacious for skin disorders such as atopic dermatitis. Consequently, PDE4 inhibitors including cilomilast and AWD 12-281 have been tested in several models of allergic and irritant skin inflammation. These PDE4 inhibitors displayed strong anti-inflammatory action in models of allergic contact dermatitis in mice, in the arachidonic acid induced skin inflammation in mice and in ovalbumin sensitised guinea pigs. The determination of cytokines in skin homogenates revealed that both Th1 as well as Th2 cytokines are suppressed by PDE4 inhibitors, indicating an anti-inflammatory activity in both the Th2 dominated acute phase as well as the Th1 dominated chronic phase of atopic dermatitis. Due to the suppression of Th1 cytokines, activity can also be expected in psoriasis. Results of early clinical trials with both topically (cipamfylline, CP80,633) and systemically (CC-10004) active PDE4 inhibitors demonstrated efficacy in atopic dermatitis and in the case of CC-10004, also in psoriasis. AWD 12-281 (GW 842470) is currently under clinical evaluation for the topical treatment of atopic dermatitis. Results concerning clinical efficacy of this potent and selective PDE4 inhibitor are anxiously awaited.

Abstract:  Effects of the histamine H₄ receptor antagonist JNJ 7777120 (1‐[(5‐chloro‐1H‐indol‐2‐yl)carbonyl]‐4‐methylpiperazine) were tested in two models of allergic contact dermatitis. Dermatitis was induced by 2,4‐dinitrochlorobenzene and toluene‐2,4‐diisocyanate, which differ in their Th1–Th2 profile in that way that 2,4‐dinitrochlorobenzene is a classical contact allergen with a pronounced Th1‐mediated inflammation, while the respiratory chemical allergen toluene‐2,4‐diisocyanate induces a Th2‐dominated inflammation. JNJ 7777120 (15 mg/kg) administered 2 h and 30 min before and 1 h after challenge did not reduce the hapten‐induced ear swelling determined 24 h after challenge. This was confirmed by histological evaluation of the ear skin. A repeated administration of the haptens to the rostral part of the back of sensitized animals resulted in a frequent scratching behaviour. An administration of JNJ 7777120 (15 mg/kg) 30 min before challenge reduced this hapten‐induced scratching significantly. The H₁ receptor antagonist cetirizine also reduced the scratching bouts in sensitized mice. A combination of H₁ and H₄ receptor antagonists resulted in the strongest inhibition of scratching behaviour associated with allergic dermatitis. These results indicate that H₄ receptor antagonism fails to reduce the allergic inflammatory response but strongly inhibits allergen‐induced itch. Thus, a combination of H₄ and H₁ receptor antagonism might be a new strategy to treat pruritus related to allergic diseases like atopic dermatitis.

Summary: The highly glycosylated peptide hormone erythropoietin (EPO) plays a key role in the regulation of erythrocyte maturation. Currently, marketed EPO is produced by recombinant technology in mammalian cell cultures. The complementary DNA (cDNA) for human EPO (hEPO) was transiently and stably expressed in the moss Physcomitrella patens wild‐type and Δ‐fuc‐t Δ‐xyl‐t mutant, the latter containing N‐glycans lacking the plant‐specific, core‐bound α1,3‐fucose and β1,2‐xylose. New expression vectors were designed based on a Physcomitrella ubiquitin gene‐derived promoter for the expression of hEPO cDNA. Transient expression in protoplasts was much stronger at 10 than at 20 °C. In Western blot analysis, the molecular size of moss‐produced recombinant human EPO (rhEPO) was identified to be 30 kDa, and it accumulated in the medium of transiently transformed protoplasts to high levels around 0.5 µg/mL. Transgenic Physcomitrella Δ‐fuc‐t Δ‐xyl‐t mutant lines expressing EPO cDNA showed secretion of rhEPO through the cell wall to the culture medium. In 5‐ and 10‐L photobioreactor cultures, secreted rhEPO accumulated to high levels above 250 µg/g dry weight of moss material after 6 days. Silver staining of rhEPO on sodium dodecylsulphate‐polyacrylamide gel electrophoresis (SDS‐PAGE) taken from the bioreactor culture demonstrated a high purity of the over‐expressed secreted rhEPO, with a very low background of endogenous moss proteins. Peptide mapping of rhEPO produced by the Physcomitrella Δ‐fuc‐t Δ‐xyl‐t mutant indicated correct processing of the plant‐derived signal peptide. All three N‐glycosylation sites of rhEPO were occupied by complex‐type N‐glycans completely devoid of the plant‐specific core sugar residues fucose and xylose.

Quantum dots (QDs) are nanoparticles with strong fluorescent emission and are novel tools used in biomedical applications, but the toxicity and mechanism of cellular uptake are poorly understood. QD655-COOH (negative charge, 18 nm) consist of a cadmium/selenide core and a zinc sulfide shell with a carboxylic acid coating with an emission wavelength of 655 nm. Materials & Methods: Peripheral blood mononuclear cells were isolated from porcine blood by gradient centrifugation, and monocytes, which are CD14 positive, were purified. Monocytes were differentiated into dendritic cells (DCs) with GM-CSF and IL-4. Results: Monocytes showed cellular uptake of QD655-COOH, while lymphocytes did not. Monocyte differentiation into DCs increased the cellular uptake by sixfold when dosed with 2 nM of QD655-COOH. Transmission electron microscopy depicted QD655-COOH in the cytoplasmic vacuoles of DCs. Twelve endocytic inhibitors demonstrated QD655-COOH endocytosis in DCs, which was recognized by clathrin and scavenger rece...

The prevalence of allergic skin disorders has increased rapidly, and development of therapeutic agents to alleviate the symptoms are still needed. In this study, we orally or topically administered the Janus kinase (JAK) inhibitors, tofacitinib and oclacitinib, in a mouse model of dermatitis, and compared the efficacy to reduce the itch and inflammatory response. In vitro effects of JAK inhibitors on bone marrow–derived dendritic cells (BMDCs) were analyzed. For the allergic dermatitis model, female BALB/c mice were sensitized and challenged with toluene-2,4-diisocyanate (TDI). Each JAK inhibitor was orally or topically applied 30 minutes before and 4 hours after TDI challenge. After scratching bouts and ear thickness were measured, cytokines were determined in challenged skin and the cells of the draining lymph node were analyzed by means of flow cytometry. In vitro, both JAK inhibitors significantly inhibited cytokine production, migration, and maturation of BMDCs. Mice treated orally with JAK inhibitors showed a significant decrease in scratching behavior; however, ear thickness was not significantly reduced. In contrast, both scratching behavior and ear thickness in the topical treatment group were significantly reduced compared with the vehicle treatment group. However, cytokine production was differentially regulated by the JAK inhibitors, with some cytokines being significantly decreased and some being significantly increased. In conclusion, oral treatment with JAK inhibitors reduced itch behavior dramatically but had only little effect on the inflammatory response, whereas topical treatment improved both itch and inflammatory response. Although the JAK-inhibitory profile differs between both JAK inhibitors in vitro as well as in vivo, the effects have been comparable.